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1
Perutz, Mark A. (Mark Andrew). "An investigation of price dispersion in Internet auctions." Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/9195.
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Thesis (M.B.A.)--Massachusetts Institute of Technology, Sloan School of Management, 2000.<br>Also available online on DSpace at MIT.<br>Includes bibliographical references (leaf 37).<br>It can be observed that in consumer-to-consumer on-line auctions, there is a strong degree of price dispersion, even in liquid markets with a large number of bids per auction item. This Thesis research strives to quantify such dispersion and present explanations for the key findings on the nature of price dispersion in on-line auctions of like goods: Although contrary to common sense and public opinion, I found no significant correlation of winning bid price with feedback rating. This is true for low, medium-high and high value goods and for both new and used goods. This observation holds for all ranges of feedback ratings. Of all of the other variables of an auction listing: (shipping costs, amount of opening bid, number of bids, accepted payment types, picture in listing, and the use of reserve prices), only picture in listing and use of reserve prices are correlated with winning bid price. This observation holds for all types of goods examined. However, correcting for these variables does not significantly reduce price dispersion. The majority of the dispersion in winning bid prices of same-good auctions can be explained by the unique ability of the on-line auction process to obtain the reservation prices of buyers in the market, through its use of maximum bid amounts and proxy bidding. An auction winning bid curve for a good can be constructed by aggregating the winning bid prices of all auctions of that good over a period of time. The downward sloping and isoelastic nature of this curve can be explained in part by the downward sloping demand curve for that good, made up by the range of premiums buyers are willing to pay in order to increase their chances of winning the auction, and getting the item sooner. The exact shape of the curve can be further explained and in fact reconstructed by an examination of the statistics of grouping bids in auctions. Arbitrage to take advantage of the dispersion of winning bid prices can be shown to be possible, and in theory it appears to be surprisingly profitable. This suggests that on-line auction markets are only weakly market efficient. Several explanations were explored as to why arbitrage has not been pursued, thereby eliminating the observed dispersion. These explanations include the unseen non-monetary transaction and arbitrage costs, the level of sophistication necessary to capitalize on opportunities, and the persisting immaturity of the consumer-to-consumer on-line auction market.<br>by Mark Andrew Perutz.<br>M.B.A.
2
O'Leary, Michael Boyer 1969. "Geographic dispersion in teams : its history, experience, measurement, and change." Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/16883.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Sloan School of Management, 2002.<br>Vita.<br>Includes bibliographical references.<br>This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.<br>This thesis begins with the simple argument that geographic dispersion has gone surprisingly unexamined despite its role as the domain-defining construct for geographically dispersed teams (a.k.a. "virtual teams"). The last few years have seen slow but steady growth in field studies of such teams, but our understanding of geographic dispersion and the role it plays in work is stillquite limited. The thesis attempts to open the "black box" of geographic dispersion, show that it is far from a new phenomenon in organizations, understand the ways in which it is experienced, propose ways in which it can be measured, and understand the effects of doing work at increasing degrees of dispersion. It does so through three studies which combine qualitative and quantitative methods, and draw on archival, survey, observational, and interview data. Study 1 uses rich archival data covering more than two centuries (1670-1950) of the life of one firm - i.e., the Hudson's Bay Company - to understand its far-flung managers' experience of dispersion. It shows that the managers experienced their dispersion through a combination of coordination, communication, isolation, and control challenges. It also serves as a "typifier," showing that modem "virtual" teams have deep historical roots. Study 2 proposes a multi-dimensional definition of dispersion, including spatial-temporal distance and configuration, as well as a series of new measures to capture those dimensions. It explores the measures and their relationship to communications frequency in a sample of 115 dispersed project teams from a Fortune 500 company.<br>(cont.) Study 3 is based on field research with nine geographically dispersed internal consulting teams in a large, national humanitarian aid organization. It follows them from the inception to the completion of their work and compares two teams in detail. One team was moderately dispersed and one was a pilot for a more fully dispersed approach to the internal consulting projects. It finds that perceptions about timing and dispersion differ from more objective measures like those in Study 2. It also shows how dispersion is a challenge for team boundaries and calls for more attention to the weighting of different team effectiveness criteria. Keywords: geographic dispersion, teams, virtual teams, effectiveness, communications, history.<br>by Michael Boyer O'Leary.<br>Ph.D.
3
Gajadharsingh, Asshvin. "Étude de solitons en dispersion management (DM) au moyen des moments d'ordre deux." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ60720.pdf.
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He, Yangbo. "Sodic Soil Swelling and Dispersion and their Implications for Water Movement and Management." Diss., North Dakota State University, 2014. https://hdl.handle.net/10365/27543.
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North Dakota has over 1.9 million ha of sodium-affected soils, influencing water movement and crop production. This dissertation consists of four studies examining different aspects of sodic soils. The first study surveys sodium adsorption ratio (SAR) methods to determine which is the most reliable. The second and third studies investigate the dispersion and swelling functions of sodic soils. The final study examines field spatial distribution of Na in order to propose management strategies. Analytical approaches for converting alternative to standard approaches are needed. The SAR was determined from many non-standard techniques. One hundred soils were used, SARe and 1:5 soil/water SAR1:5 determined using shaking, stirring, and a USDA-NRCS method were compared. Three of the methods influenced the SAR1:5 values. Electrical conductivity (EC), SAR, and Ca/Mg ratios influence dispersion. Three pure clay minerals (montmorillonite, kaolinite and illite) were pretreated by variable Na and cation ratios and absorbance was determined using spectrophotometer for dispersion. Calcium-Mg ratios across the same SAR did not influence clay dispersion. Dispersion increased with higher SAR and reduced EC whereas no dispersion for kaolinite. Swelling is associated with hydration of clays, which forces clay tactoids to separate. Four soil series from North Dakota field sites were used. To assess swelling, field capacity (FC) was used as proxy. The study found that soil Na and soluble salt concentrations were two important chemical factors influencing FCW. The FCW increases with increased SAR and lower levels of EC. These results indicate that maintaining an EC level above 4 dS m-1 may mitigate swelling, which is an issue considered in tile drainage. Over- and under-application of amendments in sodic soils was studied in a 8.1 ha sodic soil field. At each site, samples were taken from two depths; electromagnetic (EM38) and elevation readings were done. Elevation was significantly correlated with soil variables except for Na%. The EM38 was reliable to express soil EC and was correlated with Na% and dispersion. Therefore, conducting the EM38 and RTK may allow site-specific management of Na. Improved knowledge of sodic soils dispersion, swelling, and field distribution will benefit researchers and farmers in managing their fields.<br>NRCS Conservation Innovation Grant<br>China Scholarship Council<br>North Dakota Water Resources Research Institute
5
Docherty, Andrew Engineering UNSW. "Collision induced timing shifts in wavelength-division-multiplexed optical fiber communications systems." Awarded by:University of New South Wales. Engineering, 2004. http://handle.unsw.edu.au/1959.4/19337.
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Long distance repeaterless optical fiber communications systems are currently used to transmit most internet and telephone information worldwide. The growth of photonic telecommunications technology has produced systems with very high bit-rate per fiber, but this still falls short of its potential capacity. Currently systems that are able to transmit even higher bit-rates are being developed utilizing dense wavelength-division-multiplexing (WDM) to maximally utilize the bandwidth potential of optical fibers. One of the most important factors that limits the bit-rate achievable in a such a WDM optical communications system is the cross-talk between channels caused by pulse collisions. In this thesis a consistent mathematical theory is used to analyze the frequency and timing shifts caused collisions between two WDM channels. This theory is applied to the systems currently most promising for next-generation photonic telecommunications; the dispersion managed (DM) soliton and 'quasi-linear' systems. Self-contained formulae are obtained which accurately predict the timing shifts suffered in these systems with a wide range of parameters. These formulae require an order of magnitude less computational time that direct numerical simulations. Several mathematical techniques are introduced to obtain computationally efficient formulae for complete and incomplete collisions in both systems. For complete collisions we use the Poisson sum transform to change the calculation to a sum in the Fourier domain. For incomplete collisions we use asymptotic integration to obtain approximate formulae. For quasi-linear systems we simplify the Laplace method even further to obtain elementary formulae. We show that using a combination of these methods the timing shift for incomplete and complete collisions in a wide range of system configurations can be obtained in comparatively small computational times. We find that for systems with small DM map strength the timing shift from widely separated channels is significant. For quasi-linear systems with large DM map strength this is negligable and the timing shift decreases with the square of the channel frequency separation. We also find the timing shift from closely spaced channels is higher for quasi-linear systems than for DM soliton systems operating at the same average dispersion.
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Raubenheimer, Heidi. "Managing portfolio managers : the impacts of market concentration, cross-sectional return dispersion and restrictions on short sales." Thesis, Stellenbosch : Stellenbosch University, 2012. http://hdl.handle.net/10019.1/20266.
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Thesis (PhD)--Stellenbosch University, 2012.<br>The impacts on the active management of investment portfolios of a) market concentration, b) cross-sectional return dispersion and c) restrictions on short sales are explored in this thesis. The context is the fund sponsor’s management of their investment managers in a South African equity investment environment. Some of the findings here are developed analytically and some make use of multiple simulated investment views and their corresponding optimal portfolio solutions to document the size and nature of the inefficiencies that are created by these three factors.
The cross-sectional volatility of asset returns in an investment universe represents a carrying capacity for active risk taking: the higher the cross-sectional volatility, the greater the opportunity for active risk taking. Cross-sectional volatility is shown to be an important consideration when setting active risk targets. It is shown that, to remain efficient, active risk should be reduced during periods of low cross-sectional dispersion and vice versa. The sensitivity of active risk estimates to changes in the cross-sectional dispersion of their investment universe is demonstrated and sponsors should therefore exercise caution when reacting to changes in the active risk estimates of their funds. Cross-sectional volatility is shown to be time-varying and is related to similarly varying dispersion in realised fund returns. The ex post performance of competing portfolio managers therefore require correction for this heteroscedasticity and an effective weighted adjustment is recommended.
Active managers can only fully express their views in an environment where their mandated conditions accommodate their conviction and level of risk taking. The short sale restriction is shown to be materially binding when applied to a concentrated benchmark such as the ALSI where only a few of the stocks comprise most of the total investment weight. The more concentrated the benchmark and the higher the active risk target, the wider the distribution of individual asset weights in the portfolio will be and the more binding the weighting constraints will be. It is shown that constraints on short positions are more binding on assets with small weightings in the benchmark illustrating the asymmetrical sub-optimal effect of these constraints when they are applied uniformly across the investment opportunity set. It is argued that requiring long-only managers to increase their active positions and/or active risk in a concentrated investment environment further constrains them in their ability to express their best investment view and increases their competitive disadvantage relative to unconstrained funds taking similar risk.
The research presented in this thesis measures the nature and size of the impacts of the market concentration, cross sectional return dispersion and restrictions on short sales that are implied by the investment mandate on the quality of the investment portfolio, providing analysis and techniques which can inform and improve the quality of the relationship between fund sponsor and fund manager. The more appropriate the investment mandate and the monitoring of the fund’s performance subject to this mandate, the more effective the manager’s risk-taking on behalf of their investors will be. This is the principle that this research aims to serve.
7
Blachetta, Marie [Verfasser]. "Dispersion von Marketingaktivitäten in Business-to-Business Unternehmen : Merkmale, Messung, Einflussfaktoren und Auswirkungen / Marie Blachetta." Berlin : Freie Universität Berlin, 2020. http://d-nb.info/1215099401/34.
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Van, Reenen Reenen James. "An empirical investigation into cross-sectional return dispersion on the South African equity market." Thesis, Stellenbosch : Stellenbosch University, 2013. http://hdl.handle.net/10019.1/85655.
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Thesis (MComm)--Stellenbosch University, 2013.<br>ENGLISH ABSTRACT: This study examines the role of cross-sectional return dispersion in portfolio management by examining two topics. To begin with, the study considers why return dispersion changes over time. Given the influence of return dispersion on active portfolio return opportunity, it is important for managers to understand why return dispersion changes over time. For a sample of South African listed shares over the period June 1996 to December 2011, univariate time-series analysis reveals significant serial correlation in return dispersion which may be modelled using ARMA (1, 1) and GARCH (1, 1) processes. Further analysis within a rational economic framework reveals that return dispersion is countercyclical to aggregate economic activity and related to both local and foreign economic uncertainty.
The study then considers the relationship between return dispersion and the return to investment strategies. If substantial association between return dispersion and any investment strategy exists, then it is possible for managers and fund sponsors to augment an understanding of when active return opportunity is high with strategies for exploiting return opportunities. Continuing within the rational economic framework, the study uses Spearman‟s rank correlation coefficients to show a significant positive relationship between return dispersion and the value premium. In aggregate, these findings suggest that it is possible for South African investors to understand why return dispersion changes over time, as well as how to take advantage of changes in return dispersion.<br>AFRIKAANSE OPSOMMING: Hierdie studie ondersoek die rol van opbrengsverspreiding oor die kruissnit van „n mark in portefeuljebestuur deur twee onderwerpe te bestudeer. Eerstens bestudeer die studie hoekom opbrengsverspreiding oor tyd verander. Gegewe die invloed van opbrengsverspreiding op aktiewe beleggingsgeleentheid is dit belangrik vir bestuurders om te verstaan hoekom opbrengsverspreiding oor tyd verander. Vir „n steekproef van Suid Afrikaanse aandele oor die periode Julie 1996 tot Desember 2011 dui enkelvoudige tydreeks analise aan dat opbrengsverspreiding beduidende outokorrelasie het, waar die outokorrelasie beskryf word deur ARMA (1, 1) en GARCH (1, 1) prosesse. Verdere analise binne „n rasionele ekonomiese raamwerk dui daarop dat opbrengsverspreiding kontra-siklies aan makro-ekonomiese aktiwiteit is en verwant is aan beide plaaslike en buitelandse ekonomiese onsekerheid.
Die studies ondersoek daarna die verhouding tussen opbrengsverspreiding en die opbrengs van beleggings strategieë. Indien daar „n noemenswaardige verhouding is tussen opbrengsverspreiding en enige beleggings strategie, dan kan bestuurders beter oordeel watter strategieë hoë opbrengste lewer wanneer beleggingsgeleenthede hoog is. Die studie hou binne „n rasionele ekonomiese raamwerk en gebruik Spearman se rang-orde korrelasie koeffisiënte om „n beduidende positiewe verwantskap tussen opbrengsverspreiding en die opbrengs van die waardepremie aan te dui. As „n geheel dui hierdie bevindinge daarop aan dat dit moontlik is vir Suid-Afrikaanse beleggers om te verstaan hoekom opbrengsverspreiding oor tyd verander asook hoe om voordeel uit die verwantskappe te trek.
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Rezk, Rasha Saber Mahmoud. "Exploring the constraining influence of product attributes on value network configuration and dispersion." Thesis, University of Cambridge, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.708854.
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Klingebiel, Sandro. "Picosecond pump dispersion management and jitter stabilization in a petawatt-scale few-cycle OPCPA system." Diss., Ludwig-Maximilians-Universität München, 2013. http://nbn-resolving.de/urn:nbn:de:bvb:19-159662.
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The petawatt field synthesizer (PFS) is a high-power optical parametric chirped-pulse
amplification (OPCPA) system under development, which aims at generating fewcycle
pulses with high energies of several Joule. The availability of light pulses with
these unique parameters will enable an efficient generation of even shorter attosecond
pulses with significantly higher photon flux than achievable today [1]. Not
only the real-time observation, but also the control of charge transfer in molecular
systems will become feasible for the first time [2].
The technique for realizing the ambitious PFS specifications is short-pulse pumped
OPCPA in mm-thin crystals. The reduced crystal thickness allows for ultra-broadband
amplification. The pump-pulse duration is reduced to a picosecond—compared to
100 ps to nanosecond pump-pulse duration in conventional high power OPCPA systems.
The shortened pulse duration facilitates higher pump intensities whereby an
efficient amplification in the mm-thin crystals is achieved.
The demonstration of this novel scheme in the PFS project will allow its use in
the extreme light infrastructure (ELI)[3]—a pan-European high-power laser project.
Based on the PFS technology for the front end, the ELI will generate exawatt peakpower
pulses and therefore facilitate the study of laser-matter interaction in an unprecedented
intensity range [4].
This work describes the CPA-aspects of a suitable chirped pulse amplification (CPA)
pump laser for the PFS OPCPA system. The diode-pumped Yb:YAG amplifiers up to
an energy of 300 mJ (at 1030 nm) are presented in combination with the dispersion
management. The application of spectral-amplitude shaping in conjunction with
an Yb:glass amplifier with broader bandwidth than Yb:YAG enables an unprecedented
bandwidth of 3.5nm in the Yb:YAG amplifier at this energy level. Simulations
show that a similar bandwidth can be maintained for the full amplifier system.
The pulses with 200 mJ could be compressed to 900 fs, close to the transform limit.
Later changes in the stretcher increase the bandwidth more and compression down
to 740 fs is demonstrated. To date, these are the highest peak power pulses generated
in Yb:YAG. For the application as OPCPA pump, the so generated pulses are
frequency doubled in a DKDP crystal.
Another key aspect of this work is the synchronization of the OPCPA pump and
signal pulses. In spite of optical synchronization of both pulses, a large timing fluctuation
between these pulses is measured at the first OPCPA stage. The high accuracy
jitter measurement setup and a series of measurements, which showed that the
stretcher/compressor setup is the main source of jitter, are presented. Theoretical
investigations yield that the optical delay in a compressor is orders of magnitude
more sensitive to angle changes compared to free space propagation. This makes the
stretcher and compressor extremely sensitive for timing jitter caused by turbulent
air or mechanical instabilities. This novel insight helped us to significantly reduce
the jitter to 100 fs and to demonstrate the feasibility of the PFS concept with first
broad-band OPCPA experiments.<br>Das PFS OPCPA System befindet sich zurzeit im Aufbau und zielt darauf ab, ultrakurze
Lichtpulse mit wenigen optischen Zyklen und einigen Joule Pulsenergie zu
erzeugen. Wenn Lichtpulse mit diesen einzigartigen Parametern verfügbar werden,
können kürzere Attosekundenpulse mit höherer Effizienz und deutlich höherem
Photonenfluss als bisher generiert werden [1]. Die Anwendung der so erzeugten Attosekundenpulse
könnte erstmalig die Beobachtung in Echtzeit und die Kontrolle
von Ladungsübergängen in Molekularen Systemen ermöglichen [2].
Die Technik, um die PFS Spezifikationen zu erreichen ist OPCPA mit mm dünnen
Kristallen, gepumpt mit kurzen Pulsen. Die reduzierte Kristalldicke ermöglicht
ultra-breitbandige Verstärkung. Die Pumppulsdauer ist dabei auf eine Pikosekunde
reduziert, im Vergleich zu 100 ps bis Nanosekunden Pulsdauer in konventionellen
Hochleistungs-OPCPA Systemen. Dies ermöglicht höhere Pumpintensitäten, wodurch
eine effiziente Verstärkung in den kurzen Kristallen gewährleistet wird.
Die Demonstration dieses neuartigen Verstärkungsschemas innerhalb des PFS Projektes
erlaubt dessen Nutzung in ELI[3]—einem gesamt-europäische Laser Projekt.
Basierend auf der PFS-Technologie für das Frontend wird ELI Lichtpulse mit Exawatt
Spitzenleistung generieren, wodurch Laser-Materie-Wechselwirkung in einem bis
dahin unerreichten Intensitätsbereich untersucht werden kann [4].
Diese Arbeit beschreibt die Entwicklung eines geeigneten CPA Pumplasers für das
PFS OPCPA-System. Die diodengepumpten YB:YAG Verstärker bis zu einer Energie
von 300 mJ (bei 1030 nm) werden in Kombination mit dem Dispersionsmanagement
präsentiert. Die Anwendung von spektralem Amplitudenformen in Verbindung mit
einem breitbandigen Verstärker ermöglicht eine bis dahin unerreichte Bandbreite
von 3.5nm in Yb:YAG bei diesem Energieniveau. Simulationen zeigen, dass ähnliche
Bandbreiten für das vollständige Verstärkersystem erreicht werden können. Die
Pulse mit 200 mJ wurden auf 900 fs (nah am Transformlimit) komprimiert. Spätere
Veränderungen im Strecker führen zu einer vergrößerten Bandbreite, wodurch eine
Kompression auf 740 fs ermöglicht wurde. Aktuell ist dies die höchste Pulsspitzenleistung,
die je in Yb:YAG generiert wurde. Für die Anwendung als OPCPA Pumpe
werden die so generierten Pulse in einem DKDP Kristall frequenzverdoppelt.
Ein weiterer Schwerpunkt dieser Arbeit ist die Synchronisation der OPCPA Pumpund
Signalpulse. Trotz optischer Synchronisation beider Pulse wurde eine große
zeitliche Schwankung zwischen diesen Pulsen am Ort der ersten OPCPA Stufe gemessen.
Der Messaufbau wird vorgestellt und eine Reihe von Messungen zeigt, dass der
Strecker/Kompressor des Pumplasers die Hauptursache der zeitlichen Schwankungen
von einigen hundert Femtosekunden ist. Theoretische Untersuchungen ergeben,
dass der Strecker und Kompressor extrem sensitiv sind für zeitliche Schwankungen,
die durch Turbulenzen in Luft oder durch instabile mechanische Komponenten hervorgerufen
werden können. Diese neue Einsicht hat geholfen, diese Schwankungen
auf 100 fs zu reduzieren und die Machbarkeit des PFS Konzeptes mit ersten breitbandigen
OPCPA Experimenten zu demonstrieren.
11
Charlier, Steven Daniel. "A multi-level investigation of emergent leadership and dispersion effects in virtual teams." Diss., University of Iowa, 2012. https://ir.uiowa.edu/etd/3274.
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The overarching goal of the proposed study is to develop and test a mediated multi-level model of leadership emergence in virtual teams, which aims to better understand not only the processes that result in leadership emergence in self-managed virtual teams, but also how patterns of emergent leadership and team member dispersion can impact team performance in collaborative activities. Virtual teams, which can be defined as "a collection of individuals who are geographically and/or organizationally or otherwise dispersed and who collaborate via communication and information technologies in order to accomplish a specific goal" (Zigurs, 2003), continue to grow in importance as to how organizations function in the 21st century (Hertel, Konradt, & Orlikowski, 2004; Lipnack & Stamps, 2000), and the benefits to companies and individuals are numerous. For employees, virtual teamwork offers flexibility in work-life balance, a decrease in time spent in travel and commuting, and a greater range of work-related opportunities and experiences, particularly for individuals with physical disabilities. For organizations, virtual teams offer cost savings on office space and travel, an increased knowledge base and accelerated organizational learning, access to a wider range of expertise and qualified labor, and increased productivity (Jude-York, Davis, & Wise, 2000; Gillam & Oppenheim, 2006).
The model to be tested in the proposed study is predicated on the input--mediator--output--input (IMOI) model proposed by Ilgen, Hollenbeck, Johnson, & Jundt (2005). Also, heeding the recent call for researchers to better incorporate the potential of attribution theory (see Heider, 1958; Kelley, 1973; Weiner, 1986) in explaining organizational behavior (Martinko, Harvey, & Dasborough, 2010), the interpersonal attribution model proposed by Gilbert & Malone (1995) is applied within the IMOI framework for the purposes of this study. At the individual level, the model provides a theoretical linkage between communication behaviors and several outcomes, including team member perceptions/attributions and, ultimately, emergent leadership. At the team level, the model also incorporates the effect of leadership pattern differences across teams, as well as differences in level of virtuality, on overall team performance.
Based on the results of an experiment involving 86 four-person teams, it was found that configuration and collocation have significant effects on team performance and peer perceptions of individual team members. A curvilinear relationship was found between the level of dispersion among team members and team performance, such that performance generally decreased as team dispersion increased, yet performance improved at the high end of the dispersion continuum. Collocation also had strong positive effects on perceptions of trust, ability, and leadership emergence. In terms of the relationships between communication-related behaviors and emergent leadership, task-based communications proved to be the strongest predictor of emergent leadership. The use of texting language was positively associated with perceptions of leadership emergence as well. These results have significant practical implications for the design of virtual teams from both a team configuration and a team member skills/individual differences perspective. Several avenues of future research are also discussed.
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Sundaresan, Sasi Sekaran. "ATOMISTIC MODELING OF PHONON BANDSTRUCTURE AND TRANSPORT FOR OPTIMAL THERMAL MANAGEMENT IN NANOSCALE DEVICES." OpenSIUC, 2014. https://opensiuc.lib.siu.edu/dissertations/854.
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Monte Carlo based statistical approach to solve Boltzmann Transport Equation (BTE) has become a norm to investigate heat transport in semiconductors at sub-micron regime, owing mainly to its ability to characterize realistically sized device geometries qualitatively. One of the primary issues with this technique is that the approach predominantly uses empirically fitted phonon dispersion relations as input to determine the properties of phonons so as to predict the thermal conductivity of specified material geometry. The empirically fitted dispersion relations assume harmonic approximation thereby failing to account for thermal expansion, interaction of lattice waves, effect of strain on spring stiffness, and accurate phonon-phonon interaction. To circumvent this problem, in this work, a coupled molecular mechanics-Monte Carlo (MM-MC) platform has been developed and used to solve the phonon Boltzmann Transport Equation (BTE) for the calculation of thermal conductivity of several novel and emerging nanostructures. The use of the quasi-anharmonic MM approach (as implemented in the open source NEMO 3-D software toolkit) not only allows one to capture the true atomicity of the underlying lattice but also enables the simulation of realistically-sized structures containing millions of atoms. As compared to the approach using an empirically fitted phonon dispersion relation, here, a 17% increase in the thermal conductivity for a silicon nanowire due to the incorporation of atomistic corrections in the LA (longitudinal acoustic) branch alone has been reported. The atomistically derived thermal conductivity as calculated from the MM-MC framework is then used in the modular design and analysis of (i) a silicon nanowire based thermoelectric cooler (TEC) unit, and (ii) a GaN/InN based nanostructured light emitting device (LED). It is demonstrated that the use of empirically fitted phonon bandstructure parameters overestimates the temperature difference between the hot and the cold sides and the overall cooling efficiency of the system, thereby, demanding the use of the BTE derived thermal conductivity in the calculation of thermal conductivity. In case of the light-emitting device, the microscopically derived material parameters, as compared to their bulk and fitted counterparts, yielded ~3% correction (increase) in optical efficiency. A non-deterministic approach adopted in this work, therefore, provides satisfactory results in what concerns phonons transport in both ballistic and diffusive regimes to understand and/predict the heat transport phenomena in nanostructures.
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Valuntaitė, Vaida. "The Investigation and Assessment of the Man-made Ozone Formation and Dispersion." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2009. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2009~D_20090608_190741-86415.
Full textAbstract:
The dissertation comprises the general characteristic of the work,
5 chapters, conclusions and recommendations, references and list of published works on the topic of the dissertation. The dissertation covers 149 pages,
78 illustrations, 17 tables.
In introduction chapter the problem topicality is considered, the aims and tasks of the work are formulated, the novelty of the research is described, the author’s reports and publications as well as the dissertation structure are presented. Chapter 1 is intended for the review of literature. The survey of ozone sources in working premises and the environment air is presented as well as methods of the ozone concentration determination and its dispersion simulation are discussed. At the end of the chapter conclusions are formulated and the dissertation tasks are concretized. In chapter 2 the methodology of the ozone concentration determination with the ozone analyzer and passive samplers as well as the measurement methods of aerosol particles and meteorological, microclimatic parameters are described. In chapter 3 the results obtained during experimental investigations are discussed: the ozone concentration changes near technogenic sources of this pollutant, the influence of meteorological and microclimatic parameters on the ozone concentrations changes, the relation of aerosol particles with the ozone concentration. Ozone concentrations measured by different methods are compared and the results of comparative measurements are... [to full text]<br>Disertaciją sudaro įvadas, 5 pagrindiniai skyriai, darbo išvados ir rekomendacijos, literatūros sąrašas, publikacijų sąrašas. Bendra disertacijos apimtis – 149 puslapiai, 80 iliustracijų, 17 lentelių.
Įvadiniame skyriuje nagrinėjamas problemos aktualumas, formuluojamas darbo tikslas bei uždaviniai, aprašomas mokslinis darbo naujumas, pristatomi autoriaus pranešimai ir publikacijos, disertacijos struktūra. Pirmasis skyrius skirtas literatūros apžvalgai. Jame pateikta ozono šaltinių darbo patalpose ir aplinkos ore apžvalga, aptariami ozono koncentracijos nustatymo ir jos sklaidos modeliavimo metodai. Skyriaus pabaigoje formuluojamos išvados ir konkretinami disertacijos uždaviniai. Antrajame skyriuje aprašomi ozono koncentracijos nustatymo ozono analizatoriumi ir pasyviaisiais kaupikliais metodika bei aerozolio dalelių ir meteorologinių, mikroklimato parametrų matavimo metodai. Trečiajame skyriuje aptariami eksperimentinių tyrimų metu gauti rezultatai apie: ozono koncentracijos kitimą prie technogeninių šio teršalo šaltinių, meteorologinių ir mikroklimato parametrų įtaką ozono koncentracijos pokyčiams, aerozolio dalelių sąryšį su ozono koncentracija. Lyginamos ozono koncentracijos matuotos skirtingais metodais ir aptariami lyginamųjų matavimų rezultatai. Ketvirtajame skyriuje pateikti RISK programa sumodeliuoti ozono sklaidos nuo šaltinio rezultatai. Penktajame skyriuje pasiūlytas technologinis sprendimo variantas, leidžiantis sumažinti ozono koncentracijas prie technogeninių... [toliau žr. visą tekstą]
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Henson, Eric Luis. "Evaluation of a regulatory system designed to control industrial air emissions and an analysis of an air dispersion model case study." Master's thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-09192009-040218/.
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Klingebiel, Sandro [Verfasser], and Stefan [Akademischer Betreuer] Karsch. "Picosecond pump dispersion management and jitter stabilization in a petawatt-scale few-cycle OPCPA system / Sandro Klingebiel. Betreuer: Stefan Karsch." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2013. http://d-nb.info/1038152348/34.
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Shkarayev, Maxim. "Effects of Nonlinearity and Disorder in Communication Systems." Diss., The University of Arizona, 2008. http://hdl.handle.net/10150/194744.
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In this dissertation we present theoretical and experimental investigation of the performance quality of fiber optical communication systems, and find new and inexpansive ways of increasing the rate of theinformation transmission.The first part of this work discuss the two major factors limiting the quality of information channels in the fiber optical communication systems. Using methods of large deviation theory from statisticalphysics, we carry out analytical and numerical study of error statistics in optical communication systems in the presence of the temporal noise from optical amplifiers and the structural disorder of optical fibers. In the slowly varying envelope approximation light propagation through optical fiber is described by Schr\{o}dinger's equation. Signal transmission is impeded by the additive (amplifiers) and multiplicative (birefringence) noise This results in signal distortion that may lead to erroneous interpretation of the signal. System performance is characterized by the probability of error occurrence. Fluctuation of spacial disorder due to changing external factors (temperature, vibrations, etc) leads to fluctuations of error rates. Commonly the distribution of error rates is assumed to be Gaussian. Using the optimal fluctuation method we show that this distribution is in fact lognormal. Sucha distribution has ""fat"" tails implying that the likelihood of system outages is much higher than itwould be in the Gaussian approximation. We present experimental results that provide excellent confirmation of our theoretical predictions.In the second part of this dissertation we present some published work on bisolitons in the dispersion managed systems. Modern communication systems use light pulses to transmit tremendous amounts of information. These systems can be modeled using variations of the Nonlinear Shrodinger Equation where chromatic dispersion and nonlinear effects in the glass fiber are taken into account. The best system performance to date is achieved using dispersion management. We will see how the dispersion management works and how it can be modeled. As you pack information more tightly the interaction between the pulsesbecomes increasingly important. In Fall 2005, experiments in Germany showed that bound pairs of pulses (bisolitons) could propagate significant distances. Through numerical investigation we found parametric bifurcation of bisolitonic solutions, and developed a new iterative method with polynomial correction for the calculation of these solutions. Using these solutions in the signal transmission could increase the transmission rates.
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Ramantanis, Petros. "Contribution to the analysis of optical transmission systems using QPSK modulation." Phd thesis, Institut National des Télécommunications, 2011. http://tel.archives-ouvertes.fr/tel-00765380.
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The constant demand for capacity increase, together with the foreseen saturation of the single-mode optical fiber, paved the way to technological breakthroughs that have completely changed the landscape of fiber-optic telecommunications. The most important advance was, undeniably, the practical implementation of a coherent detection with the help of high-speed electronics. This has, first, enabled the use of advanced modulation formats that allowed for a more efficient use of the fiber bandwidth, compared to the classical On-Off Keying, while adapted algorithms could not be used in order to mitigate the optical signal degradation. This thesis began a little after the advent of coherent detection and its main objective was to revisit the propagation effects in optical transmission systems using "Quadrature phase shift keying" (QPSK) modulation in the context of terrestrial systems, i.e. for transmission distances of up to about 2000 km. The manuscript is divided into two parts. The first part is dedicated to a study on the data sequences that need to be used in numerical simulations, when advanced modulation is involved. Fiber propagation, and in particular the interplay between chromatic dispersion and nonlinearities, usually introduce a nonlinear inter-symbol interference (ISI) to the transmitted signal. Since this ISI depends on the actual transmitted data pattern, it is obvious that the choice of the sequence used in our numerical simulations will have a direct influence on the estimated channel quality. Since, an infinite length, random sequence is impractical; we very commonly use pseudorandom" (PR) sequences, i.e. finite-length, deterministic sequences with balanced pattern statistics that seem to be random. In the first part we describe the method of generating M-level (with M>2) pseudorandom sequences and we detail their properties. In addition, we propose numerical tools to characterize the non-pseudorandom sequences that we use in numerical simulations, or we are sometimes forced to use in laboratory experiments. Finally, we present results of numerical simulations that quantify the necessity to use PR sequences as a function of our system parameters. After having established the "fairest possible" finite sequences, in the second part of the manuscript, we focus on the study of the nonlinear propagation, in the context of a transmission system using QPSK modulation and assuming a variable dispersion management and fiber type. Specifically, we numerically study the signal statistics due to the interplay of chromatic dispersion and nonlinear effects, neglecting all polarization or multi-wavelength effects and the amplifier noise. In this context, we were first interested in determining whether some empirical laws developed for OOK systems, can be also used in the case of QPSK modulation, such as the criterion of cumulative nonlinear phase (ΦNL) or laws that allow for a quick optimization of the dispersion management. Next we reveal the importance of a global phase rotation added to the initial signal constellation, as a parameter that can provide interesting information for the post-optimization of our system. We also discuss the fact that the constellation shape critically depends on the applied dispersion management, while there are generally 3 types of constellations, concerning the complex signal statistics: (1) the phase variance is higher than the amplitude variance (2) the amplitude variance is higher than the phase variance and (3) the received signal constellation resembles to a constellation of a signal under the influence of just an Additive White Gaussian Noise. Finally, we provide a phenomenological explanation of the constellations shapes revealing the fact that different data sub-sequences suffer from a different kind of signal degradation, while we also use this information to define a parameter that quantifies the potential benefit from a MAP (Maximum A Posteriori probability) correction algorithm
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De, Franca Catalao Igor. "Différence, dispersion et fragmentation sociospatiale : explorations métropolitaines à Brasilia et Curitiba." Phd thesis, Université d'Avignon, 2013. http://tel.archives-ouvertes.fr/tel-01037942.
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Le passage du XXe au XXIe siècle a été accompagné d'intenses transformationssociospatiales, qui mettent en échec l'avenir de la ville. D'un côté, des processusd'individualisation et de segmentation sociale s'accroissent et articulément produisent ou réitèrent les inégalités. D'autre côté et de façon dialectique, la production de tissus urbains de plus en plus dispersés se confirme, caractérisée par des discontinuités territoriales et des densités variables du centre vers la périphérie. Dans ce contexte, l'urbanisation se diffuse mondialement, affecte tous les espaces et articule des différentes échelles, de façon à produire l'urbain au-delà des villes. Au Brésil, spécialement à partir des années 1970, les transformations sociospatiales mentionnées ci-dessus se sont liées à des processus de modernisation nationaux. Les métropoles de Curitiba et de Brasilia se sont développées dans cette période, chacune à sa manière, mais de façon plus accentuée à Brasilia. Toutes deux ont néanmoins été marquées par des inégalités et par la dispersion urbaine. Deux objectifs ont orienté la discussion proposée dans cette thèse : examiner la corrélation entre dispersion urbaine et fragmentation sociospatiale ; et expliquer comment ces deux processus se réalisent à Brasilia et à Curitiba. La recherche comparative a été menée à partir d'études et recherches sur les deux villes ainsi que directement dans leurs agglomérations. Des observations, des visites de terrain dans les zones résidentielles fermées et dans les villes de la périphérie métropolitaine ont été faites, mais aussi des entretiens avec des résidents. De ce fait, le cadre analytique de la thèse permet de comprendre qu'il y a, à Curitiba et surtout à Brasilia, des logiques fragmentaires qui favorisent la dissolution de l'unité morphologique tant par la dispersion des tissus urbains que par la segmentation sociale et la reproduction des inégalités. Ceci contribue à la création de limites à la mise en place du droit à la ville comme droit à la différence et amène à une nécessaire réflexion sur la notion de justice spatiale comme moyen approprier de surmonter les inégalités.
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Kobayashi, Wataru [Verfasser], and Helmut [Akademischer Betreuer] Zacharias. "Development of a high-repetition-rate intense ultrashort optical parametric chirped-pulse amplifier system with a global dispersion management / Wataru Kobayashi. Betreuer: Helmut Zacharias." Münster : Universitäts- und Landesbibliothek der Westfälischen Wilhelms-Universität, 2012. http://d-nb.info/1027027881/34.
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Ludington, Timothy Shane Ludington. "The degree of impairment of foraging in crayfish (Orconectes virilis) due to insecticide exposure is dependent upon turbulence dispersion." Bowling Green State University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1466173210.
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HASAN, KHALID. "STUDY OF SPATIAL/TEMPORAL PATTERNS OF RADON RELEASES FROM THE K-65 SILOS, USING DISPERSION MODELING AND GIS: A CASE STUDY AT THE DEPARTMENT OF ENERGY'S FERNALD ENVIRONMENTAL MANAGEMENT PROJECT, CINCINNATI, OHIO." University of Cincinnati / OhioLINK, 2001. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1008268951.
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Liu, Shuang. "Analyst Behavior, Crowdsourced Research and the Capital Markets." Thesis, University of Sydney, 2020. https://hdl.handle.net/2123/22962.
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This thesis consists of three papers revolving around stock analysts’ behavior, crowdsourced research and the capital markets. Using a news-based index of economic policy uncertainty (EPU), the first paper documents that EPU is positively related to analyst forecast dispersion and the number of analysts following the firm, and negatively related to analyst forecast accuracy. The uncovered relations are robust to various endogeneity corrections and hence are likely causal. Cross-sectional analyses indicate that the impacts of EPU on analyst behavior are more pronounced for firms with higher exposure to EPU, higher information asymmetry among investors, and higher transient institutional ownership. These findings suggest that EPU increases analyst following possibly because it increases investor demand for analyst research. The second paper studies the dispersion effect that aggregate analyst forecast dispersion negatively predicts future market returns. I find that the market return predictive power of aggregate dispersion only exists prior to 2005. The dispersion-return relation is partly driven by its correlation with the conditional equity premium. I find that the impact of investor sentiment on dispersion effect is also significant only prior to 2005. I do not find the short-sale constrained stocks experience higher dispersion effect. The third paper examines whether increased monitoring stemming from an innovation in financial technology affects corporate managers’ earnings management behavior. I find that firm managers significantly manipulate earnings upward after their firms being covered by Estimize, an open platform which crowdsources short-term earnings forecasts. This suggests that coverage by Estimize exerts pressure on firm managers to meet short-term earnings targets. I further show that this effect works through two channels: Estimize sets higher earnings targets than sell-side analysts do, and also reduces analyst short-term downward bias.
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Masuraha, Anand. "Evaluation of the AERMOD Model and Examination of Required Length of Meteorological Data for Computing Concentrations in Urban Areas." Connect to Online Resource-OhioLINK, 2006. http://www.ohiolink.edu/etd/view.cgi?toledo1145653382.
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Thesis (M.S.C.E.)--University of Toledo, 2006.<br>Typescript. "A thesis [submitted] as partial fulfillment of the requirements of the Master of Science degree in Civil Engineering." Bibliography: leaves 104-108.
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Norhidayah, Binti Abdull. "Model Simulation and Health Risk Assessment on Traffic-Induced Air Pollution in Urban Environments：A Case Study of Kyoto City, Japan." Doctoral thesis, Kyoto University, 2020. http://hdl.handle.net/2433/259034.
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京都大学<br>0048<br>新制・課程博士<br>博士(工学)<br>甲第22766号<br>工博第4765号<br>新制||工||1745(附属図書館)<br>京都大学大学院工学研究科都市環境工学専攻<br>(主査)教授 米田 稔, 教授 高野 裕久, 准教授 藤森 真一郎<br>学位規則第4条第1項該当<br>Doctor of Philosophy (Engineering)<br>Kyoto University<br>DFAM
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Dahlquist, Josefin, Martin Larsson, and Tea Rickfält. "Hydrologi i Ulleråker : En studie om dagvattenhantering och dess inverkan på grundvatten." Thesis, KTH, Industriell ekologi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-210675.
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Vattenbehovet stiger i världen till följd av ökande befolkning. Med ökad urbaniseringskapas mer hårdgjorda ytor där föreningar ackumuleras. Dagvattnet transporterar dessa föroreningar som således kan nå grundvattnet. Ett miljömål har antagits i Sverigeför att skydda grundvattentäkter och därmed säkra framtida dricksvattenförsörjning. Rullstensåsar innehåller stora grundvattenmagasin och har hög infiltrationsförmåga för vatten från markytan. Uppsala kommun tar 95 % av sitt dricksvatten från rullstensåsenUppsalaåsen. Ulleråker ligger strax söder om Uppsala stadskärna och i området planerasen ny hållbar stadsdel. Stadsdelen ligger delvis rakt på Uppsalaåsens kärna och det ärviktigt att inget förorenat dagvatten kan infiltrera åsen då det kan påverka dricksvattenförsörjningennegativt. Syftet med detta projekt är att bidra till en djupare förståelse för hur grundvattnet kan påverkas av dagvattenhanteringen vid den planerade nybyggnationen av Ulleråker. Målet med projektet är att utvärdera vad hållbar dagvattenhantering innebär och hur tekniken är planerad att implementeras i Ulleråker. Projektet innefattar även utvärderingav alternativa tekniker som applicerats i andra stadsbyggnadsprojekt med hållbarhetsprofil som skulle kunna tillämpas i Ulleråker. Projektet är till största delen en litteraturstudie där planprogram för Ulleråker studeratsför att identifiera och utvärdera risker som kan uppstå till följd av dagvattenhanteringen,men även för att utvärdera de åtgärder som planeras. En modellering utfördesäven för att studera föroreningsspridning från en bilväg i området. Slutligen studeradesandra stadsbyggnadsprojekt för att se om deras lösningar skulle kunna implementeras i Ulleråker. De främsta riskerna för grundvattenkvaliteten relaterade till dagvattenhantering i Ulleråker har identifierats till släckvatten vid brand, dagvatten- och avloppsledningarsamt utsläpp under byggnationen. Planerade åtgärder är att utifrån sårbarhetsområdensätta restriktioner för markanvändningen och hur byggnationen ska gå till, särskilt vidåskärnan. Dagvattenhantering ska utgå från ett robust dagvattensystem baserat på ettsystemtänk genom att inget dagvatten ska infiltrera marken i sårbara områden. Detta ska säkerställas genom ett tätt vattenledningssystem som avleder dagvattnet till dagvattendammardär det fördröjs och renas. Hantering av släckvatten vid bränder ska ske genom att täta markytor kring byggnader hindrar släckvatten från markinfiltration. Endast vatten får användas som släckvätska. Modelleringen över föroreningsspridning frånen bilväg i Ulleråker visar att föroreningar avsätts på en yta upp till 6 meter från vägbanansmitt. Ett annat stadsbyggnadsprojekt som studerades var Augustenborg i Malmödär dagvattensystemet bygger på öppna lösningar med bland annat kanaler, dammar ochgröna tak. Slutsatserna är att hållbar dagvattenhantering generellt går ut på att fördröja ochrena dagvattnet lokalt. De lösningar som tagits fram för Ulleråkers dagvattenhanteringbygger på täta ledningar och dammar som fördröjer vattnet innan det når ytvattenrecipienten Fyrisån eller kopplas på Uppsala kommuns dagvattenledningar. I Ulleråker blir det viktigt att kontrollprogram finns och efterföljs för att minska risken för förorening av grundvattnet. Föroreningar från Ulleråkersvägen sprids upp till 6 meter ut från vägensmitt och det är således viktigt att täta denna yta så att föroreningarna inte kan infiltreramed dagvattnet ner till Uppsalaåsen. Lösningar från Augustenborg som skulle kunna implementeras i Ulleråker är gröna tak med tjocka jordlager då de renar vatten mer effektivtän tak med tunnare jordlager.<br>Water demand rises in the world as a result of increasing population. Increased urbanizationcreates more impervious surfaces where pollutants accumulate. The stormwater transports these pollutants, which can thus reach the groundwater. An environmental goal has been adopted in Sweden to protect the groundwater and thus secure future drinking water supply. Eskers contain large groundwater storages and have high infiltration capacity for water fromthe ground surface. Uppsala municipality takes 95 % of its drinking water from the Uppsalaesker. Ulleråker is located just south of Uppsala city centre and in the area a new sustainabledistrict is planned. The district is partly located on the Uppsala esker’s core and it is importantthat no contaminated water is able to infiltrate the esker as it may affect the drinking watersupply negatively. The purpose of this project is to contribute to a deeper understanding of how the groundwatercan be affected by the stormwater management in the planned new construction of Ulleråker.The aim of the project is to evaluate what sustainable stormwater management means andhow the technology is planned to be implemented in Ulleråker. The project also includesevaluation of alternative techniques applied in other urban construction projects with sustainability profile that could be implemented in Ulleråker. The project is mainly a literature study where Ulleråker's plan program has been studied to identify and evaluate risks that may occur as a result of stormwater management, but also to evaluate the planned measures. A modelling was also conducted to study pollutant dispersio nfrom a roadway in the area. Finally, other urban construction projects were studied to see if their solutions could be implemented in Ulleråker. The main risks of groundwater quality related to stormwater management in Ulleråker have been identified as extinguishing water in the event of fire, stormwater and sewage pipelinesand leakage during construction. The planned measures are to impose restrictions on land usebased on vulnerability areas and how the construction is executed, especially at the core of the esker. Stormwater management should be based on a robust water system based on a system thinking so that no water will infiltrate the soil in vulnerable areas. This is to be ensured by a dense water pipeline system that leads the stormwater into surface water dams where it isdelayed and cleaned. Handling of extinguishing water should be done by sealing land surfaces around buildings preventing extinguishing water from soil infiltration. Only water may beused as extinguishing fluid. The modelling of pollution dispersion from a roadway inUlleråker shows that contaminants are deposited on a surface up to 6 meters away from the centre of the roadway. The studied urban building project Augustenborg in Malmö has its stormwater system based on open solutions, including channels, ponds and green roofs. The conclusion is that sustainable stormwater management in general is based on delayingand cleaning stormwater locally. The solutions developed for Ulleråker’s stormwatermanagement are based on dense conduits and ponds that delay the water before reaching thesurface water receptor Fyrisån or are connected to Uppsala municipality's water pipelines. In Ulleråker it becomes important that control programs are in place and followed to reduce therisk of groundwater contamination. Pollution from Ulleråkersvägen is spread up to 6 meters out of the middle of the road and it is therefore important to seal this area so that thecontaminants cannot infiltrate with the stormwater to Uppsalaåsen. Solutions from Augustenborg that could be implemented in Ulleråker are green roofs with thick soil layers asthey clean water more efficiently than roofs with thinner soil layers.
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Zmijewski, Nicholas. "Effects of Watershed Dynamics on Water Reservoir Operation Planning : Considering the Dynamic Effects of Streamflow in Hydropower Operation." Doctoral thesis, KTH, Vattendragsteknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-201612.
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Water reservoirs are used to regulate river discharge for a variety of reasons, such as flood mitigation, water availability for irrigation, municipal consumption and power production purposes. Recent efforts to increase the amount of renewable power production have seen an increase in intermittent climate-variable power production due to wind and solar power production. The additional variable energy production has increased the need for regulating the capacity of the electrical system, to which hydropower production is a significant contributor. The hydraulic impact on the time lags of flows between production stations have often largely been ignored in optimization planning models in favor of computational efficiency and simplicity. In this thesis, the hydrodynamics in the stream network connecting managed reservoirs were described using the kinematic-diffusive wave (KD) equation, which was implemented in optimization schemes to illustrate the effects of wave diffusion in flow stretches on the resulting production schedule. The effect of wave diffusion within a watershed on the variance of the discharge hydrograph within a river network was also analyzed using a spectral approach, illustrating that wave diffusion increases the variance of the hydrograph while the regulation of reservoirs generally increases the variance of the hydrograph over primarily short periods. Although stream hydrodynamics can increase the potential regulation capacity, the total capacity for power regulation in the Swedish reservoir system also depends significantly on the variability in climatic variables. Alternative formulations of the environmental objectives, which are often imposed as hard constraints on discharge, were further examined. The trade-off between the objectives of hydropower production and improvement of water quality in downstream areas was examined to potentially improve the ecological and aquatic environments and the regulation capacity of the network of reservoirs.<br><p>QC 20170210</p>
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Heuser, Aden Elizabeth. "An Examination of the Use of Synchronous Computer-Mediated Communication Technology in Work Teams." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1258424936.
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Ramantanis, Petros. "Contribution to the analysis of optical transmission systems using QPSK modulation." Electronic Thesis or Diss., Evry, Institut national des télécommunications, 2011. http://www.theses.fr/2011TELE0020.
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La demande constante de capacité et la saturation prévue de la fibre monomode ont conduit récemment à des avances technologiques qui ont complètement changé le paysage des télécommunications à fibre optique. Le progrès le plus important était la mise en œuvre d'une détection cohérente à l'aide d'électronique rapide. Cela a permis pas seulement l'utilisation de formats de modulation qui promettent une utilisation plus efficace de la bande passante, mais aussi l’utilisation des algorithmes adaptés pour combattre la dégradation du signal optique due à la propagation. Cette thèse a commencé un peu après le début de cette « ère du cohérent » et son principal objectif était de revoir les effets physiques de la propagation dans des systèmes de transmission terrestres, utilisant le format de modulation QPSK (Quadrature Phase Shift Keying). Le manuscrit est divisé en deux parties. La première partie est consacrée à une étude sur les séquences des données qui doivent être utilisés dans les simulations numériques, lorsqu’un format de modulation avancée est impliqué. La propagation, et en particulier l'interaction entre la dispersion chromatique et les non-linéarités, introduisent une interférence inter-symbole (ISI). Vu que cet ISI dépend de l’enchainement des données transmises, il est évident que le choix de la séquence a une influence sur la qualité estimée du canal. Etant donné que des séquences aléatoires infinies ne sont pas pratiquement réalisables, nous utilisons souvent des séquences « pseudo-aléatoires » (PR), i.e. des séquences déterministes de longueur finie, avec des statistiques équilibrés, qui semblent être aléatoires. Dans la première partie, nous décrivons la méthode de génération de séquences PR avec M. niveaux (M> 2) et nous détaillons leurs propriétés. En outre, nous proposons des outils numériques pour caractériser les séquences non pseudo-aléatoires qu’on utilise souvent dans des simulations, ou parfois aussi dans des expériences au laboratoire. Enfin, nous présentons les résultats de simulations qui permettent de quantifier la nécessité d'utiliser des séquences PR en fonction des paramètres du système. Après avoir établi les séquences finies "les plus adaptées", dans la seconde partie du manuscrit, nous nous concentrons sur l'étude de la propagation, dans le contexte d'un système de transmission QPSK et en supposant une gestion de dispersion et un type de fibre variables. Plus précisément, nous étudions numériquement les statistiques de signaux dégradés dus à l'interaction de la dispersion chromatique avec les effets non linéaires, en négligeant tout effet de polarisation ou inter-canaux, aussi que le bruit des amplificateurs. Dans ce contexte, nous étions intéressés à déterminer si certaines lois empiriques développées pour les systèmes OOK, sont valable dans le cas d'une modulation QPSK, tels que le critère de la phase non-linéaire cumulée (ΦNL) ou des lois qui permettent une optimisation de la gestion de dispersion. Ensuite, nous révélons l'importance de la rotation de la constellation du signal initial, comme un paramètre qui peut fournir des informations pour la post-optimisation de notre système. Nous discutons également autour du fait que la forme de la constellation dépend de la gestion de dispersion et concernant les constellations nous concluons qu'il y en a généralement 3 types, avec: (1) une variance de phase supérieure à la variance d'amplitude (2) une variance d'amplitude supérieure à la variance de phase et (3) avec le signal ayant une constellation qui ressemble à la constellation d’un signal sous l'influence d'un bruit blanc gaussien additif. Enfin, nous fournissons une explication phénoménologique des formes des constellations révélant le fait que des sous-séquences différentes conduisent à un « type » différent de dégradation et nous utilisons ces informations pour définir un paramètre qui quantifie le bénéfice potentiel d'un algorithme de correction du type MAP(Maximum A Posteriori Probability)<br>The constant demand for capacity increase, together with the foreseen saturation of the single-mode optical fiber, paved the way to technological breakthroughs that have completely changed the landscape of fiber-optic telecommunications. The most important advance was, undeniably, the practical implementation of a coherent detection with the help of high-speed electronics. This has, first, enabled the use of advanced modulation formats that allowed for a more efficient use of the fiber bandwidth, compared to the classical On-Off Keying, while adapted algorithms could not be used in order to mitigate the optical signal degradation. This thesis began a little after the advent of coherent detection and its main objective was to revisit the propagation effects in optical transmission systems using "Quadrature phase shift keying" (QPSK) modulation in the context of terrestrial systems, i.e. for transmission distances of up to about 2000 km. The manuscript is divided into two parts. The first part is dedicated to a study on the data sequences that need to be used in numerical simulations, when advanced modulation is involved. Fiber propagation, and in particular the interplay between chromatic dispersion and nonlinearities, usually introduce a nonlinear inter-symbol interference (ISI) to the transmitted signal. Since this ISI depends on the actual transmitted data pattern, it is obvious that the choice of the sequence used in our numerical simulations will have a direct influence on the estimated channel quality. Since, an infinite length, random sequence is impractical; we very commonly use pseudorandom" (PR) sequences, i.e. finite-length, deterministic sequences with balanced pattern statistics that seem to be random. In the first part we describe the method of generating M-level (with M>2) pseudorandom sequences and we detail their properties. In addition, we propose numerical tools to characterize the non-pseudorandom sequences that we use in numerical simulations, or we are sometimes forced to use in laboratory experiments. Finally, we present results of numerical simulations that quantify the necessity to use PR sequences as a function of our system parameters. After having established the “fairest possible” finite sequences, in the second part of the manuscript, we focus on the study of the nonlinear propagation, in the context of a transmission system using QPSK modulation and assuming a variable dispersion management and fiber type. Specifically, we numerically study the signal statistics due to the interplay of chromatic dispersion and nonlinear effects, neglecting all polarization or multi-wavelength effects and the amplifier noise. In this context, we were first interested in determining whether some empirical laws developed for OOK systems, can be also used in the case of QPSK modulation, such as the criterion of cumulative nonlinear phase (ΦNL) or laws that allow for a quick optimization of the dispersion management. Next we reveal the importance of a global phase rotation added to the initial signal constellation, as a parameter that can provide interesting information for the post-optimization of our system. We also discuss the fact that the constellation shape critically depends on the applied dispersion management, while there are generally 3 types of constellations, concerning the complex signal statistics: (1) the phase variance is higher than the amplitude variance (2) the amplitude variance is higher than the phase variance and (3) the received signal constellation resembles to a constellation of a signal under the influence of just an Additive White Gaussian Noise. Finally, we provide a phenomenological explanation of the constellations shapes revealing the fact that different data sub-sequences suffer from a different kind of signal degradation, while we also use this information to define a parameter that quantifies the potential benefit from a MAP (Maximum A Posteriori probability) correction algorithm
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Hasan, Khalid. "Study of spatial/temporal patterns of radon releases from the K-65 silos, using dispersion modeling and gis a case study at the department of energy's Fernald environmental management project, Cincinnati, Ohio. /." Cincinnati, Ohio : University of Cincinnati, 2001. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=ucin1008268951.
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Percel, Gwendoline. "Réponse des espèces lignicoles à la disponibilité des habitats en forêt tempérée : approche multi-échelles du micro-habitat au paysage." Thesis, Orléans, 2018. http://www.theses.fr/2018ORLE2055/document.
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La sylviculture intensive modifie la composition, la structure et la dynamique des peuplements, réduisant notamment la densité et la diversité des attributs forestiers caractéristiques des stades de sénescence (bois mort et micro-habitats portés par les arbres). Ces éléments représentent des habitats essentiels pour les espèces lignicoles. A l’échelle du massif, la planification des opérations sylvicoles va créer une discontinuité spatiale de ces micro-habitats, pouvant être perçue comme une source de fragmentation pour de nombreuses espèces. Cependant, les effets ont été peu explorés au sein des forêts tempérées exploitées. L’objectif de cette thèse est d’évaluer l’effet de la disponibilité des micro-habitats (quantité et configuration) à de multiples échelles spatiales sur les communautés et les populations d’espèces lignicoles, afin de fournir in fine des connaissances pour la spatialisation des stratégies de conservation. Nous avons proposé une méthodologie statistique permettant de prédire la distribution des micro-habitats au sein du massif de Compiègne (France). En s’appuyant sur cette cartographie prédictive, nous avons montré que différentes guildes de coléoptères saproxyliques, définies en fonction de traits d’histoire de vie liés aux capacités de dispersion, répondaient à la structure du paysage à différentes échelles spatiales. La modélisation de la dynamique des métapopulations d’une bryophyte épixylique (Dicranum viride) nous a permis de mettre en évidence l’importance de la dispersion sur les processus de colonisation/extinction qui sous-tendent les patrons d’occurrence des espèces observés à l’échelle du massif. Nos résultats soulignent le rôle central du bois mort et des micro-habitats, qui peuvent être considérés comme un levier de gestion pertinent. Augmenter leur quantité et optimiser leur arrangement spatial intra et inter-peuplement apparaît essentiel pour assurer la persistance des espèces lignicoles au sein des massifs forestiers gérés<br>Intensive forestry induces a simplification of forest stand structure, composition, and dynamics, resulting in a decrease of density and diversity of old-growth forest attributes (deadwood and tree-related microhabitats). These elements represent critical habitats for lignicolous species. At the landscape scale, forest management planning create a spatial discontinuity of these microhabitats, which can be perceived as a fragmentation process for many species. Although habitat fragmentation is currently recognized as one of the major threats to biodiversity, its impact on species in managed temperate forest are still poorly understood. The objective of this work was to evaluate the effect of microhabitat availability (quantity and configuration) on species communities and populations, at multiple spatial scales, in order to provide evidence-based recommendations regarding the spatial arrangement of conservation strategies. We proposed a statistical methodology to predict the microhabitats distribution within the complex of the Compiègne forest (France). Based on this predictive mapping, we showed that different guilds of saproxylic beetles, defined according to their life history traits related to dispersal abilities, respond to the landscape structure at different spatial scales. Modelling metapopulation dynamics of an epixylic bryophyte (Dicranum viride) has highlighted the importance of dispersal on colonization/extinction processes that underlie the species’ occurrence patterns observed at the forest scale. Our results emphasize the key role of deadwood and tree-related microhabitats, which can be considered as relevant management leverage. Increase their quantity and optimize their spatial arrangement within and between forest stands, appears to be essential for persistence of the lignicolous species within managed forests
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Kazlauskas, Dainius. "Researches of H2S generation from municipal landfills and systematical evaluation of landfills pollution." Master's thesis, Lithuanian Academic Libraries Network (LABT), 2005. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2005~D_20050614_082554-89323.
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In Lithuania the amount of waste generation is increasing every year. According to national strategy, all wastes should be disposed in new regional landfills. Landfills pollutes environment with leachate and landfill gas and odours. Landfill gas consists of odorous compounds and one of them is hydrogen sulphide (H2S). Hydrogen sulphide is highly toxic and affects the nervous system with low threshold. As the landfill gas and leachate generation was word widely investigated before this work, it is not necessary to provide new researches on them. The measurements of H2S generation were provided in Jerubaiciai landfill. For the measurements was used “site-on” measurement method, measurements were provided with equipment GD/MG 7, in 51 measurement points and 2 monitoring wells, during different seasons of the year. Results of the measurement shows, that amount of H2S varies in different areas of landfill and during different seasons. The results of dispersion modeling achieved with dispersion model AERMOD, provided under calm weather conditions and under wind dominated in that session winter speed and direction, during different seasons of the year shows, that H2S spreads from landfill in longest distances from landfill’s section during summer (almost in distance equal to 2.5 km the H2S concentration is higher then Highest Allowable Concentration ). In autumn and spring this distance is equal to 1.5 km, and in winter – 800 m.<br>Susidarančių komunalinių atliekų kiekis Lietuvoje kiekvienais metais didėja. Pagal nacionalinę strategiją, visos komunalinės atliekos Turi būti deponuojamos regioniniuose sąvartynuose, kurie teršia aplinka filtratu iš sąvartyno išsiskiriančiomis dujomis bei kvapais, kurių veina iš sudedamųjų dalių yra sieros vandenilis (H2S). H2S matavimai buvo atlikti Jerubaičių sąvartyne. Iš sąvartyno išsiskiriantis H2S kiekis buvo tiriamas jo išsiskyrimo vietoje, t.y. sąvartyno teritorijoje. Šis matavimo metodas buvo pasirinktas remiantis tuo, kad iš sąvartyno išsiskiriančios taršos dydis ir poveikis priklauso nuo daugelio aplinkos faktorių. Matavimai, naudojant prietaisą GD/MG 7, buvo atlikti 59 matavimo taškuose ir 2 monitoringo šuliniuose, skirtingais metų laikai. Gauti tyrimų rezultatai parodė, kad šios medžiagos kiekis yra skirtingas įvairiose sąvartyno zonose bei įvairiais metų laikais. Norint ištirti H2S sklaidą buvo atliktas skaitmeninis dispersijos modeliavimas naudojant programą AERMOD. Jo metu vienu atveju buvo pasirinktos stabilios meteorologinės sąlygos, o kitu pasirinkti dominuojančios konkrečiu metų laiku vėjo kryptys ir greičiai. Modeliavimo rezultatai parodė, kad vasarą H2S didžiausia leistina koncentracija pasiekiama tik maždaug 2,5 kilometrų, rudenį ir pavasarį 1,5 kilometrų, o žiemą - už 800 metrų atstumu nuo sąvartyno teritorijos.
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Récapet, Charlotte. "Keeping the balance ? : Management of oxidative stress, body mass and reproduction under energetic constraints by dispersing and philopatric collared flycatchers." Thesis, Lyon 1, 2015. http://www.theses.fr/2015LYO10272/document.
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La dispersion, c’est-à-dire le déplacement d’un individu entre deux sites de reproduction, est un processus clé pour la dynamique des métapopulations et les flux de gènes. Son succès peut être modulé par des différences de phénotype ou syndromes de dispersion. Cependant, les contraintes environnementales (externes) et physiologiques (internes) qui sous-tendent ces syndromes restent mal connus. Ce projet vise à clarifier l’impact des variations environnementales et des contraintes oxydatives (liées aux espèces réactives de l’oxygène produites durant la respiration) sur les phénotypes associés à la dispersion chez un passereau, le gobemouche à collier Ficedula albicollis. La demande énergétique a été expérimentalement (i) augmentée en manipulant la surface alaire ou (ii) diminuée par une supplémentation en nourriture. L’équilibre oxydo-réducteur des gobemouches en reproduction est influencé par des interactions complexes entre facteurs intrinsèques (statut de dispersion) et extrinsèques (densité de couples reproducteurs, année, traitement expérimental). La capacité antioxydante dépend principalement des différences permanentes entre individus, alors que les pro-oxydants présentent de grandes variations intra-individu. Les variations environnementales et les contraintes énergétiques modulent aussi les différences de succès reproducteur et de comportement parental liées au statut de dispersion. Nos résultats confirment que les oiseaux dispersants et philopatriques diffèrent dans leur gestion de l’équilibre oxydo-réducteur lorsqu’il est en compétition avec l’investissement reproducteur. Ces différences pourraient avoir des conséquences à long terme sur la valeur sélective et compenser les différences de succès reproducteur entre individus dispersants et philopatriques dans les habitats de faible qualité. Ce travail souligne que les traits associés à la dispersion sont souvent déterminés par des normes de réaction à l’environnement et non des différences fixées entre individus, et améliore notre compréhension des syndromes de dispersion<br>Dispersal, i.e. individual movement between breeding sites, is a key process for metapopulation dynamics and gene flow. Its success can be modulated by phenotypic differences between dispersing and philopatric individuals, or dispersal syndromes. However, the environmental (external) and physiological (internal) constraints underlying such syndromes remain poorly known. This project aimed at clarifying the impact of environmental variation and oxidative constraints, linked to the reactive oxygen species produced during respiration, on phenotypes associated to dispersal in a passerine bird, the collared flycatcher Ficedulla albicollis. Energetic demand was experimentally (i) increased through a wing load manipulation or (ii) relieved through food supplementation. The oxidative balance of breeding flycatchers was influenced by complex interactions of dispersal status and extrinsic factors (breeding density, year, experimental treatments). Interestingly, antioxidant capacity was influenced both by permanent individual differences and by food availability, whereas measures of pro-oxidants were highly variables within individuals. Environmental variation and energetic constraints also modulated the differences in reproduction associated with dispersal: dispersing and philopatric birds differ in their management of the oxidative balance when it is competing with reproductive investment. This thesis highlights that reaction norms, rather than fixed differences, often shape traits associated to dispersal
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Cavalcante, Rosane Barbosa Lopes. "Efeito do vento e da vazão na hidrodinâmica e na dispersão de poluentes na região nordeste da Laguna dos Patos." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2018. http://hdl.handle.net/10183/172140.
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O impacto de um lançamento de efluente na qualidade da água do corpo hídrico depende de características do lançamento e do corpo hídrico, a exemplo de suas condições hidrodinâmicas. O conhecimento das relações entre os fatores envolvidos permite avaliar os riscos envolvidos, alterar a forma de lançamento de efluentes de modo a reduzir seu impacto e reduzir os custos com as formas de controle da poluição, entre outras ações. Nesse contexto, o objetivo deste trabalho é compreender as relações entre os fatores dominantes das condições hidrodinâmicas e a dispersão de poluentes na região nordeste da Laguna dos Patos, buscando identificar formas de utilizar a modelagem hidrodinâmica para melhorar a gestão do corpo hídrico e de lançamento de efluentes. A área de estudo consiste na região nordeste da Laguna dos Patos, no Rio Grande do Sul, onde o vento e a vazão afluente são os fatores determinantes de circulação de água. O modelo utilizado (IPH-A) apresentou boa representação da variação de nível, exceto pelo posto mais próximo da região estuarina, e da circulação de água. O coeficiente de dispersão foi definido a partir da comparação visual da simulação da dispersão dos sedimentos em suspensão afluentes ao Lago Guaíba e a pluma do Guaíba observada em imagens de satélite. Cenários de vento e vazão foram determinados a partir da análise da série histórica de dados de vento na estação de Rio Grande e da vazão afluente ao Lago Guaíba.Os resultados dos ventos sudoeste e nordeste foram semelhantes ao verificado na literatura com uso de modelo bidimensional para o corpo lagunar. Na região nordeste, uma célula de circulação entre o Banco das Desertas e o Banco dos Abreus é observada no sentido horário (anti-horário) para os cenários com vento sudoeste (nordeste). O vento sudeste provoca o aumento do nível na margem oeste e redução na margem leste É observada uma maior renovação de água na região ao norte do Banco das Desertas e menor troca de água com a Lagoa do Casamento do que nos cenários anteriores. Nos cenários de vento nulo, as velocidades da água na região nordeste da laguna são bastante baixas. A vazão necessária para manutenção do nível na laguna dependeu do vento predominante. Os diferentes cenários de vento produziram diferentes plumas de dispersão do lançamento de efluente simulado, seguindo os padrões da circulação de água no local. As maiores concentrações foram observadas no local de lançamento do efluente para o cenário de vento nulo e a maior área de influência foi observada para os cenários de vento nordeste (maior velocidade de vento simulada). Para os cinco dias de simulação, foi observada pouca influência da vazão afluente no nível e na circulação de água do corpo lagunar e, consequentemente, na dispersão de poluentes. Os resultados evidenciam a necessidade de as concentrações de lançamento permitidas serem estabelecidas com base em estudo da dispersão física do efluente no corpo hídrico receptor, conforme determinado pela legislação nacional para corpos d’água onde não se aplica a vazão de referência. A consideração de uma zona de mistura onde as concentrações dos parâmetros podem estar em desacorpo com o enquadramento do corpo hídrico é debatida nas discussões. As simulações permitiram ainda identificar locais prioritários para monitoramento dos efeitos do efluente lançado na qualidade da água, cenários críticos para conflitos de uso da água considerando outros usos na região e verificar possíveis consequências do encurtamento ou alongamento do emissário.<br>The aim of this study is to understand the relationship between hydrodynamic and the pollutants dispersion in the northeast region of the Patos Lagoon, looking for identify ways of using hydrodynamic modeling to improve water resources and effluent discharge management. The study area is the northeastern region of Patos Lagoon, a chocked lagoon in the brazilian state of Rio Grande do Sul, where winds and freshwater runoff drive water circulation. The model IPH-A performed well, except for the estuarine region. The dispersion coefficient was defined from the visual comparison between the dispersion of suspended sediments on Guaíba Lake simulated and observed in satellite images. The wind and freshwater runoff scenarios were determined by analyzing the historical wind data series at the Rio Grande station and the freshwater discharge of the main tributaries of Guaíba Lake. The results for the scenarios of the southwest and northeast winds were similar to those observed in the literature using a two-dimensional hydrodynamic model. In the northeast region, a circulation cell between the Banco das Desertas and Banco dos Abreus is observed clockwise (counter-clockwise) for the southwest (northeast) wind scenarios. The southeast wind increases water level in the west margin and reduces in the east margin. It is observed a more intense water exchange in the region to the north of the Banco das Desertas and less water exchange with the Casamento Lagoon than in the previous scenarios In null wind speed scenarios, the water velocities in the northeast region of the lagoon are quite low. The water inflow necessary to maintain the water level in the lagoon depends on the wind condition. Different wind scenarios produced different effluent plumes, following the local water circulation patterns. The highest concentrations were observed at the effluent discharge site for the scenario with null wind speed and the largest area of influence was observed for the northeast wind scenario (highest simulated wind speed). Due to the only 5-days period of simulation, little influence was observed of the freshwater runoff on the water level and on the lagoon circulation, and, consequently, on the dispersion of pollutants. This evidences the need for the maximum permitted concentrations of pollutants to be established based on a study of the physical dispersion of the effluent in the receiving water body, as determined by national legislation for water bodies where the reference flow does not apply. The simulations also allowed to identify priority sites for monitoring the effects of effluent discharge on water quality, critical scenarios for water use conflicts considering other uses, and to verify possible consequences of changes in emissary length.
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Janeiro, Fernando M. "Quiralidade e Não-Linearidade em Fibras Ópticas." Doctoral thesis, IST, 2004. http://hdl.handle.net/10174/2008.
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This thesis addresses the effects of chirality and nonlinearity in fiber optics. Most photonic
applications are based on conventional optical fibers in the linear regime. Although nonlinear
effects in fiber optics have been extensively studied, that is not the case with chirality. In fact,
the study of chirality in fiber optics is in its very early stages.
Maxwell’s equations are unified with Einstein’s special theory of relativity through a
tensor formulation of classical electrodynamics. Through the study of a moving dielectric
medium the general concept of bianisotropic media is introduced.
A modified Lorentz model, based on the dipole response of a single helix, is developed.
This model is used to obtain the dispersion behavior of the constitutive parameters of chiral
isotropic media (also known as optically active media).
The study of propagation in a symmetric planar chirowaveguide naturally evolves into
the analysis of the propagation characteristics of chiral optical fibers. Dispersion diagrams for
guided modes, surface and semileaky, are presented. Radiation loss in semileaky modes is also
analyzed. Semileaky modes in chirowaveguides are physically explained through the study of the
reflection problem at a planar interface between chiral media.
Propagation of solitary waves is studied in the framework of multichannel nonlinear
optical communication systems with dispersion management. A Lagrangian formulation is
developed in order to obtain optimal dispersion maps for both filtered and unfiltered optical
communication systems. A good agreement between the results obtained using this variational
approach and the Split-Step Fourier Method was found.
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Kühl, Ralf. "Dispersión retributiva y resultados: evidencia empírica en las empresas cotizadas españolas." Doctoral thesis, Universidad de Murcia, 2011. http://hdl.handle.net/10803/52189.
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La globalidad de la problemática a través de diferentes niveles jerárquicos, funciones y roles del conjunto de empleados lleva al análisis de un conjunto limitado de factores relacionados con la retribución enmarcado en el ámbito de empresas españolas cotizadas y directamente en el papel de la retribución y de las diferencias retributivas a nivel del equipo de alta dirección. Este trabajo estudia factores contextuales que mayor influencia tienen sobre la fijación del nivel retribución del equipo de alta dirección, considerando las características del trabajo de esos mismos –posición jerárquica, discrecionalidad, interdependencia de tareas, e incertidumbre– y cómo dichas características pueden influir en las diferencias salariales entre los propios miembros del equipo de alta dirección. Completado por la verificación del efecto del gobierno corporativo y el papel de los mecanismos de supervisión para controlar a los directivos (el marco de la teoría de
la agencia) se enriquece este trabajo sobre el contexto de dispersión retributiva y resultados de la empresa.<br>The globality of the problem through different hierarchical levels, functions and roles of all employees takes to the analysis of a limited set of factors related to compensation in the context of listed Spanish companies and directly on the role of pay and the pay differences at the top management team. This paper examines the contextual factors of main influence on establishing remuneration levels of top management team, considering the nature of their working activities- hierarchical position, discretion, task interdependence, and uncertainty-and how these characteristics may influence pay differences between the members of the top management team. Completed by the exploration of effects of corporate governance and the role of supervision mechanisms to control managers in the agency theory context this paper is enriched in the topic concerning pay differences and operating results.
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Teichert, Nils. "Variabilité des traits d’histoire de vie chez les Gobiidae (Sicydiinae) amphidromes de l’île de la Réunion : Sicyopterus lagocephalus (Pallas, 1770) et Cotylopus acutipinnis (Guichenot, 1863)." Thesis, Pau, 2012. http://www.theses.fr/2012PAUU3024/document.
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Les Sicydiinae amphidromes constituent une part importante des peuplements piscicoles insulaires de la région Indo-Pacifique et sont vulnérables à de nombreuses pressions anthropiques (i.e. pêcherie, dégradation et fragmentation des habitats). La reproduction a lieu en eau douce, puis les jeunes dévalent en mer où ils débutent leur croissance pendant quelques mois avant de coloniser les rivières. L’objectif est d’acquérir des connaissances sur les traits de vie de S. lagocephalus (cosmopolite) et de C. acutipinnis (endémique). Les travaux de terrain démontrent que le choix de l’habitat quotidien est fortement lié aux interactions sociales, alors que l’habitat de fraie montre une forte sélection pour des conditions morphodynamiques favorisant l’oxygénation des oeufs. Les mâles sélectionnent des sites de ponte et gardent les oeufs. L’étude expérimentale de la survie en eau douce confirme que tous les embryons libres possèdent la capacité à rejoindre la mer. L’analyse des traits de vie marins à partir des otolithes des post-larves révèle des variations saisonnières d’âge et de taille au recrutement, en lien avec la croissance et la température marine. L’examen histologique des ovaires permet de décrire les variations spatiales et temporelles de l’activité de reproduction chez les femelles en rivière et de déterminer la fécondité et la taille de première reproduction. Les variations inter et intra-spécifiques des traits de vie sontcomparées en lien avec la répartition géographique des deux espèces. Ces travaux permettent d’identifier des perspectives concrètes dans le domaine de la gestion et de la conservation sur la base des caractéristiques de la stratégie amphidrome<br>Amphidromous Sicydiinae are particularly widespread among fish freshwater assemblages of the Indo-Pacific region and are vulnerable to anthropogenic pressures (i.e. fishery, degradation and fragmentation of habitats). Spawning and hatching happen in freshwater, then offspring drift downstream to the sea where they begin their growth for a few months before recruiting in the rivers. This study aims at acquire knowledge about life traits of S. lagocephalus (cosmopolite) and C. acutipinnis (endemic). Field sampling shows that the usual habitat choice is related to social interactions, whereasspawning habitat shows a strong selection for morphodynamic conditions which favor eggs oxygenation. Males select spawning sites and care for the eggs. The experimental study of freshwater survival confirms that free embryos survival and swimming capacities are enough to drift to the ocean. Marine life history analysis, based on postlarvae otoliths examination, reveals a seasonal variation of both age and size-atrecruitment related to the larval growth rate and the sea temperature. Histological examination of ovaries is used to describe the spatial and temporal variation of reproductive activity of mature females in the rivers, and to determine fecundity and size at first reproduction. Inter and intra-specific variations of life history traits are compared in relation to the respective geographical distribution of both species. This study identifies concrete prospects for management and conservation based on the features of amphidromous life history strategy
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Foucart, Renaud. "Essays in product diversity and urban transportation." Doctoral thesis, Universite Libre de Bruxelles, 2012. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209677.
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This dissertation is about games with a continuum of players and horizontal differentiation. The first chapter explains how price dispersion can be a feature of a competitive market with homogenous information and production costs. The second chapter extends the study to group consumption. The third chapter is about multiple equilibria in urban transportation.<br>Doctorat en Sciences économiques et de gestion<br>info:eu-repo/semantics/nonPublished
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Kühl, Ralf [Verfasser], and Gregorio Sánchez [Verfasser] Marín. "La dispersión retributiva y su efecto en la eficiencia organizacional: un modelo de investigación / Ralf Kühl, Gregorio Sánchez Marín." München : GRIN Verlag, 2007. http://d-nb.info/1181203848/34.
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Schuch, Cleusa Conceição Terres. "Implementação da política da autonomia financeira em duas escolas públicas estaduais do Rio Grande do Sul : um estudo de caso." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2007. http://hdl.handle.net/10183/10836.
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O estudo enfoca o financiamento da educação pública brasileira, especificamente a implantação da política de descentralização/desconcentração de recursos às escolas estaduais do Rio Grande do Sul (RS). O tema da descentralização/desconcentração de atribuições dentro do processo de reformas vivido pela área da educação nos últimos anos, especificamente no estado do RS, somado às questões da autonomia financeira da escola, suscitou a realização do presente trabalho. A questão central de pesquisa diz respeito às possibilidades e limites da política de autonomia financeira das escolas públicas estaduais para o avanço da gestão democrática na educação pública do RS. A pesquisa abrange a análise da implementação dessa política em duas escolas públicas estaduais, localizadas no município de Guaíba (RS), no período de 1995 a 2005. Foram estudadas as fontes de recursos com as quais as escolas contam para sua manutenção, a captação de verbas na própria escola e junto à comunidade, a gestão desses recursos e suas implicações no cotidiano escolar.O método escolhido para orientar a pesquisa foi o estudo de caso, que propiciou a investigação de uma política pública educacional dentro de seu contexto, a escola. O estudo baseia-se em várias fontes de evidência, como análise de documentos, coleta de dados financeiros, entrevistas, visitas às escolas e à 12ª Coordenadoria Regional de Educação e observação de reuniões nas escolas. As categorias analíticas que dão suporte à analise são a descentralização de recursos, a autonomia financeira da escola, a gestão financeira e a gestão democrática da escola. Em síntese, esperamos discutir a importância da gestão de recursos financeiros públicos transferidos para as unidades escolares, bem como aqueles captados e geridos no próprio estabelecimento de ensino, e suas implicações com a gestão democrática.<br>This study focuses on Brazilian public education financing, especially the implantation of the policy of decentralization/dispersion of resources in the public schools in the state of Rio Grande do Sul (RS). The subject of decentralization/dispersion of attributions within the reform process experienced by the educational area in the last years, especially in Rio Grande do Sul, in addition to the questions of financial autonomy of schools, lead to the realization of the present work. The main research question is concerned to the possibilities and limits of financial autonomy policies of public schools for the democratic management progress in the public education in RS. The research includes the analyses of implementation of these policies in two public schools, located in the municipality of Guaiba (RS), from 1995 to 2005. We studied from where the resources schools have for their maintenance came from, as well as the collection of money in the school itself and in the community, the management of these resources and its implications in the routine of the schools. The method chosen to guide the research was the case study, which was biased toward the investigation of an educational public policy inside its context, the school. This study is based on many sources of evidence, as analyzing documents, collecting financial information, interviewing, visiting schools and the 12º Regional Education Coordination and observing schools meetings. The analytic categories that give support to the analysis are: the decentralization of resources, financial autonomy of the school, financial management and democratic management of the school. In short, we hope to discuss the importance of management of public financial resources transferred to the schools units, as well as that ones collected and administrated in the teaching establishment itself and its implications towards the democratic management.<br>El estudio enfoca el financiamiento de la educación pública brasileña, específicamente la implantación de la política de descentralización/desconcentración de recursos a las escuelas estaduales de Río Grande do Sul (RS). El tema de la descentralización/desconcentración de atribuciones dentro del proceso de reformas vivido por el área de la educación en los últimos años, específicamente en el Estado de RS, agregado a las cuestiones de la autonomía financiera de la escuela, suscitó la realización del actual trabajo. La cuestión central de la investigación dice respecto a las posibilidades y a los límites de la política de la autonomía financiera de las escuelas públicas estaduales para el avance de la gestión democrática en la educación pública del RS. La investigación incluye el análisis de la puesta en práctica de esta política en dos escuelas públicas estaduales, situadas en la ciudad de Guaíba (RS), en el período de 1995 el 2005. Fueron estudiadas las fuentes de los recursos con los cuales las escuelas cuentan para su mantenimiento, la captación de montajes de dinero dentro de la propia escuela y junto a la comunidad, la gestión de estos recursos y sus implicaciones en el día a día de la escuela. El método elegido para orientar la investigación fue el estudio de caso, que propició la investigación de una política pública educativa dentro de su contexto, la escuela. El estudio se basa en algunas fuentes de evidencia, como análisis de documentos, colecta de datos financieros, de entrevistas, de visitas a las escuelas y a la 12ª Coordenadoria Regional de Educación y de la observación de reuniones en las escuelas. Las categorías analíticas que apoyan el análisis son la descentralización de recursos, la autonomía financiera de la escuela, la gestión financiera y la gestión democrática de la escuela. En síntesis, esperamos discutir la importancia de la gestión de los recursos financieros públicos transferidos a las unidades escolares, bien como aquellos captados y manejados en el establecimiento educativo, y sus implicaciones con la gestión democrática.
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Guedes, Luis Fernando Ascenção. "Coordenação intraorganizacional de centros de P&D globalmente dispersos." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/12/12139/tde-02052012-202903/.
Full textAbstract:
Os investimentos em Pesquisa e Desenvolvimento têm se constituído como fonte importante de vantagem competitiva, especialmente com o aprofundamento das decorrências da globalização dos mercados. A soma dos investimentos em P&D que os 27 países-membros da Comunidade Européia fizeram em 2007 superou EUR227 bilhões, ao passo que no mesmo ano os EUA investiram US$368 bilhões em P&D. Dados da OCDE e UNESCO apontam para um aumento do investimento global em P&D de US$525 bilhões em 1996 para mais de US$1 trilhão em 2006. Tendo em vista o cenário de franca expansão das funções de Pesquisa e Desenvolvimento e do já consolidado movimento de descentralização do P&D em direção às subsidiárias da empresa multinacional, emerge a necessidade de coordenação global de esforços e uso racional dos recursos, de modo a tornar os investimentos e a gestão de P&D mais eficazes. A eficácia à qual se refere está na base da competitividade, na medida em que pode facilitar a flexibilidade da organização para fazer frente à dinâmica do mercado, auxiliar na economia de recursos e maximizar o retorno sobre os investimentos em infraestrutura e capacitação da mão-de-obra. Essa pesquisa se debruça sobre a questão da coordenação dos esforços de P&D em uma empresa multinacional de base tecnológica que tem centros de P&D em diversos países. São tratados temas relativos aos mecanismos de coordenação, sua implementação dada a estratégia de internacionalização de P&D adotada pela empresa, assim como é discutido em que medida as tecnologias de informação e comunicações podem auxiliar a empresa na missão de coordenar e integrar os esforços de todo seu P&D. Por fim, são identificados os aspectos críticos para a coordenação global dos centros de P&D, por meio da discussão sobre seus fatores facilitadores.<br>Investments in Research and Development have constituted an important source of competitive advantage, especially with the deepening of globalization of markets and its consequences. The sum of investments that the 27 member countries of the European Community did in 2007 exceeded EUR227 billion, while in the same year U.S. had invested $368 billion in R&D. UNESCO and OECD data show an increase in overall investment in R&D from $525 billion in 1996 to more than $1 trillion in 2006. Given the scenario of increasing business impact of Research and Development and the movement towards its decentralization towards the subsidiaries of multinational company, arises the need for global coordination and synergic use of resources in order to make investment and management of R&D more effective. This effectiveness lies on the basis of competitiveness, as it can facilitate the organization\'s flexibility to cope with market dynamics, can help save resources and maximize return on investments in infrastructure and training of the workforce. This research focuses on the issue of global R&D coordination in a multinational company that has geographically dispersed R&D centers. The scope encompasses issues related to coordination mechanisms implementation, the relationship between R&D internationalization and coordination mechanisms, to what extent information technologies and communications can help the company in the mission to coordinate and integrate efforts of all its R&D facilities. Finally, it is identified critical issues for the global R&D coordination, through the discussion of coordination facilitators.
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González, Domínguez Elisa. "Biology, epidemiology and control of Fusicladium eriobotryae, causal agent of loquat scab." Doctoral thesis, Universitat Politècnica de València, 2014. http://hdl.handle.net/10251/38715.
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El moteado del níspero, causado por el hongo Fusicladium eriobotryae es la principal enfermedad que afecta al cultivo del níspero, produciendo pérdidas importantes en la cosecha en los años con condiciones climáticas adecuadas. Sin embargo, no existen estudios sobre la epidemiología y el control de esta enfermedad, por lo que éstos constituyen el principal objetivo de la presente Tesis. Para ello, se va ha caracterizar in vitro y en campo la influencia de las principales variables climáticas en el desarrollo de F. eriobotryae, desarrollándose ecuaciones matemáticas que modelicen esta relación. Por otro lado, se va a llevar a cabo un modelo epidemiológico para el moteado del níspero capaz de predecir, en función de las principales variables climáticas el riesgo de infección. Además, se realizará un estudio del control de la enfermedad que comprenderá, por un lado, la evaluación in vitro y en planta de la efectividad de las principales materias activas utilizadas para el control del moteado del níspero, y por otro la evaluación del grado de resistencia de una colección de aislados de F. eriobotryae a DMI y Metil-Tiofanato y la caracterización molecular de la misma.<br>González Domínguez, E. (2014). Biology, epidemiology and control of Fusicladium eriobotryae, causal agent of loquat scab [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/38715<br>TESIS
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Cilwa, Katherine E. "Surface Plasmons Polaritons and Single Dust Particles." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1304532704.
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Andzeiewski, Simone. "Iscas tóxicas no controle de Linepithema micans (Forel, 1908) (Hymenoptera: Formicidae) e Eurhizococcus brasiliensis (Wille, 1922) (Hemiptera: Margarodidae) na cultura da videira." Universidade Federal de Pelotas, 2017. http://repositorio.ufpel.edu.br:8080/handle/prefix/3672.
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Previous issue date: 2017-02-24<br>Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES<br>A pérola-da-terra Eurhizococcus brasiliensis (Wille, 1922) (Hemiptera: Margarodidae)
é uma cochonilha subterrânea que ataca raízes de plantas cultivadas e silvestres. A
espécie é considerada a principal praga da videira no Brasil. No primeiro ínstar, a
dispersão da cochonilha é realizada com o auxílio de formigas doceiras principalmente
a Linepithema micans (Forel, 1908) (Hymenoptera: Formicidae) que se associa à
cochonilha na busca de excrementos açucarados. Nesse trabalho, foi avaliado o efeito
de iscas tóxicas a base de hidrametilnona no controle de L. micans, e
consequentemente, na infestação de E. brasiliensis em novos plantios de videira.
Inicialmente foi realizado um experimento em vasos em casa de vegetação em
outubro de 2014 com a finalidade de selecionar formulações de iscas tóxicas à base
de hidrametilnona (“grânulo pequeno”, “grânulo grande”, tipo “cereal” e gel) para o
controle de L. micans. As iscas tóxicas foram oferecidas ad libitum em porta-iscas com
substituição semanal. As avaliações foram realizadas semanalmente registrando o
número de formigas forrageando a cada 10 minutos durante uma hora sobre uma
solução aquosa de açúcar invertido 70%. A melhor formulação de isca tóxica
selecionada em casa de vegetação foi avaliada a campo em dois experimentos,
realizados em áreas naturalmente infestadas pela pérola-da-terra e por L. micans. No
primeiro, foram efetuadas aplicações semanais de 450 g/ha da isca tóxica em Flores
da Cunha, RS, e no segundo, foi avaliado uma e três aplicações semanais da mesma
dose em Caxias do Sul, RS. Mudas do porta enxerto Paulsen 1103 foram plantadas
em agosto de 2014 para o experimento em Flores da Cunha e em novembro de 2015
no experimento de Caxias do Sul, respectivamente. O monitoramento populacional
das formigas foi feito semanalmente através de armadilhas subterrâneas do tipo
“pitfall” utilizando mel e sardinha embebidos em algodão. A avaliação dos
experimentos foi realizada em maio de 2015 (Flores da Cunha) e 2016 (Caxias do
Sul), contando o número de cochonilhas presentes nas raízes. No experimento em
casa de vegetação, a isca tóxica a base de hidrametilnona formulada em “grânulo
pequeno” e “grânulo grande” controlaram a população de formigas nas primeiras
quatro semanas após o fornecimento da isca. A isca tóxica formulada em gel também
proporcionou mortalidade de 100% da população de formigas, no entanto seu controle
foi mais lento, quando comparado as outras formulações. A isca “cereal” não
proporcionou controle das formigas. A isca tóxica formulada em “grânulo pequeno”
selecionada como a mais eficaz em casa de vegetação, fornecida semanalmente no
campo, controlou a população de L. micans em 100% reduzindo a infestação da
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pérola-da-terra em 99,9%. Quando o número de aplicações da isca foi reduzido para
1 a 3, houve um controle de 100% na população de formigas no tratamento que
recebeu três aplicações até a quarta semana após o fornecimento da isca, porém as
colônias se restabeleceram ao longo do experimento e os tratamentos (uma e três
vezes) não foram eficazes no controle das espécies. Conclui-se que a formulação
granulada à base de hidrametilnona “grânulo pequeno” é eficiente no controle de L
micans em casa de vegetação e em aplicações semanais no campo. Aplicações de
uma e três vezes da isca tóxica não proporcionaram controle satisfatório das espécies
sendo necessário ajustar o número de tratamentos para um controle eficaz e
econômico de E. brasiliensis e L. micans.<br>In Brazil, Eurhizococcus brasiliensis (Wille) (Hemiptera: Margarodidae) is considered
to be the main pest of vine plants, attacking the roots of cultivated and wild plants.
Linepithema micans (Forel, 1908) (Hymenoptera: Formicidae) is the primary agent
responsible for spreading the Eurhizococcus brasiliensis, which are attracted by the
honeydew excreted by the scale insect. In this work, the effect of a hydramethylnonbased
granular toxic bait on the control of L. micans and E. brasiliensis in grapevines
was evaluated on young grapevines. An experiment was conducted in a greenhouse
in October 2014 and planted in individual pots were used to select different
formulations of toxic baits based on hydramethylnon (small granule, large granule,
cereal and gel) for the control of L. micans. The toxic baits were provided ad libitum in
bait holders, with baits being replaced weekly. Weekly evaluations were carried out
during a period of 10 weeks, with the number of foraging ants being counted every 10
minutes during 1 hour, in an aqueous solution of 70% inverted sugar. The best
formulation of toxic bait selected in greenhouse was evaluated in the field in two
experiments, carried out in areas naturally infested withe the scale and L. micans. In
the first experiment 450 g/ha/week of the toxic bait were applied in Flores da Cunha,
RS, and in the second, one and three weekly applications of the same dose were
evaluated in Caxias do Sul, RS. In August 2014, seedlings from the Paulsen 1103
rootstock were planted in Flores da Cunha and in November 2015 in Caxias do Sul.
The ants was monitored weekly in-ground pitfall traps using a honey and water solution
(70%) and sardine conserved in oil absorbed in cotton wool as food attractants.The
evaluation of the experiments was carried out in May of 2015 (Flores da Cunha) and
2016 (Caxias do Sul), counting the number of scale insects present in the roots.The
experiment conducted in a greenhouse, the hydramethylnon based toxic bait in the
formulation small granule and large granule controlled the ant population in the first 4
weeks of application.The gel formulation of the hydramethylnon toxic bait also provided
100% mortality of the population of ants; however, its control was slower when
compared with the other two formulations and the cereal formulation did not differ from
the control. The small granule toxic bait, applied weekly, effectively reduced the
infestation of L. micans, controlling 100% of the population of ants and reducing the
infestation of E. brasiliensis by 99.9%. When the number of bait applications was
reduced to 1 to 3, there was a 100% reduction in the ants in the treatment that received
three applications until the fourth week after application of the bait, but the colonies
were re-establishment.The small granule toxic bait, applied weekly, effectively reduced
the infestation of L. micans in greenhouse and field.The reduction of the number of
applications (one and three times) did not provide satisfactory control and it will be
10 necessary to adjust the number of treatments for an efficient and economical control
of the two species.
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Benamrane, Yasmine. "La gestion des situations d’urgence à l’interface entre expertise et décision : quelle place pour les outils de modélisation des dispersions NRBC-E et de leurs conséquences ?" Thesis, Paris, ENMP, 2015. http://www.theses.fr/2015ENMP0013/document.
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Aujourd'hui, l'évaluation des conséquences environnementales et sanitaires d'événements majeurs liés aux rejets dans l'atmosphère de substances radiologiques ou chimiques est, de plus en plus, basée sur la mise en œuvre d'outils de modélisation. La capacité de ces outils à appréhender de manière toujours plus fine l'ampleur spatiale et temporelle de ce type d'événements contribue à leur positionnement croissant en appui aux situations d'urgence. Cependant, l'accident de Fukushima a souligné qu'en dépit de cette tendance, l'apport des outils n'est pas encore optimal au regard de l'environnement décisionnel de l'organisation de sécurité civile en charge, notamment, des décisions de protection des populations. Cette recherche s'attèle donc, sur la base d'interviews et d'observations d'exercices de crise, à clarifier la place des outils de modélisation en situation d'urgence. L'étude suggère qu'à ce jour, la gestion de ces situations prend place dans un processus de co-construction de sens entre acteurs d'expertise NRBC-E et décideurs, favorisant l'atteinte de consensus en matière de prise de décision. L'étude met également en lumière l'importance que joue le COD, de par sa structure même, comme lieu d'échange entre acteurs aux expertises et expériences complémentaires, dans la perception et la gestion des changements de contexte. Ainsi, nous suggérons qu'en se positionnant au niveau de l'évaluation de la situation, les outils de modélisation fournissent une information qui respecte les pratiques actuelles dans l'aide à la décision en situation d'urgence et le respect des rôles et expertises de chaque acteur. Dans cette optique, les modèles de dispersion et d'impact sont donc susceptibles de s'intégrer au développement plus global d'outils d'aide à la gestion des crises auprès de l'organisation de sécurité civile, principalement comme soutien à la construction d'une représentation collective et dynamique de la situation entre expert et décideur<br>Environmental and health impact assessment of accidental or intentional releases of potentially hazardous materials in the atmosphere is increasingly supported by the development of modeling tools. Their potential to assess the spatial and temporal extent and severity of toxic plumes contributes to their growing development as CBRN-E emergency support tools. However, the Fukushima nuclear accident underlined that their support is not yet optimal regarding civil security organizations in charge of population protection. This research therefore tends to clarify the role of these modelling tools in emergency management. For this purpose, interviews and observations of crisis exercises have been conducted. This study suggests that nowadays, CBRN-E emergency management takes place in a sensemaking co-constructing process between CBRN-E experts and emergency managers contributing to the achievement of consensus in the decision making process. This study also highlights the key role played by the crisis center, regarding its proper organizational structure as a sharing place between actors with complementary expertise and experience, in the perception and response to changing circumstances. Thus, this study suggests that by providing situation assessment results, modeling tools meet the current practices both in terms of emergency support tools used for civilian protection organization and in respect of each actors' contributions. In this perspective, these modelling tools are likely to end up being part of the development of crisis management support tools for building a collective representation of the CBRN-E situation between expertise and decision
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Rost, Bagudanch Josep. "L'efecte de la gestió forestal post-incendi sobre l'avifauna i la dispersió de llavors per ocells frugívors." Doctoral thesis, Universitat de Girona, 2011. http://hdl.handle.net/10803/32137.
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The objective of this thesis is to analyze the effect of the transformation in the habitat that postfire salvage logging supposes on birds in Mediterranean pine forests, at different levels: species, community and ecosystem, focusing on the bird-mediated seed dispersal process. Salvage logging with commercial purposes is the main factor that determines the species composition after a fire, with the substitution of forest birds by open-habitat species, some of which hold an unfavourable conservation status in Europe. On the other hand, wood debris piles built by non-profitable burnt wood favour the presence of seed disperser frugivorous birds, and these structures show more seed dispersal than other microhabitats, and a higher abundance of bird-dispersed plants, so that it is recommendable to build them in managed burned forests.<br>L'objectiu de la tesi és analitzar l'efecte de la transformació de l'hàbitat que suposa la gestió forestal post-incendi sobre els ocells en pinedes mediterrànies, a diferents nivells: d'espècies, de comunitat, i d'ecosistema, sobre el procés de dispersió de llavors de plantes que duen a terme alguns ocells frugívors. La tala dels arbres cremats amb finalitats principalment comercials és el principal factor que determina la composició d'espècies d'ocells després d'un incendi forestal, amb la substitució d'ocells forestals per espècies lligades a espais oberts, algunes de les quals presenten una situació de conservació desfavorable a Europa. Per altra banda, els pilons de branques construïts amb restes de tala afavoreix la presència d'ocells dispersors de llavors, i aquestes estructures també presenten una pluja de llavors més elevada que altres microhàbitats, i una abundància més gran de plantes dispersades per ocells, per la qual cosa es recomana la seva construcció.
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Rodrigues, Juliana Pilato. "Modelagem matemática da dispersão de poluentes atmosféricos como etapa de pré-seleção de locais para instalação de estações de monitoramento da qualidade do ar em Paranaguá - PR." Universidade Tecnológica Federal do Paraná, 2016. http://repositorio.utfpr.edu.br/jspui/handle/1/1850.
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CAPES<br>Este estudo teve por objetivo sugerir locais para o monitoramento da qualidade do ar no município de Paranaguá-PR. Para tal, foi utilizada modelagem matemática de dispersão de poluentes atmosféricos, associada ao levantamento de informações sobre adensamento populacional e distribuição de equipamentos urbanos nos bairros do município. Com o uso do software de modelagem AERMOD foram simuladas as concentrações de CO, NOX, SO2, PTS e HCT, considerando emissão veicular, industrial e do Porto de Paranaguá. Os dados meteorológicos utilizados nas simulações consistiram em uma série horária de três anos. As concentrações máximas horárias para CO, NOX, SO2, PTS e HCT foram 5572 μg m-3, 5741 μgm-3, 1539 μg m-3, 3368 μg m-3 e 247 μg m-3, respectivamente. Para a média do período modelado as concentrações para CO, NOX, SO2, PTS e HCT foram 340 μg m-3, 343 μg m-3, 94μg m-3, 116 μg m-3 e 38,6 μg m-3, respectivamente. Foram sugeridos para a instalação de estações de monitoramento da qualidade do ar os seguintes bairros: Alboit para estação industrial, por pertencer à Zona de Interesse Portuário, que abriga atividades potencialmente poluidoras; Costeira para estação residencial devido a sua relativa proximidade à zona portuária; Vila Horizonte para estação veicular, por estar localizado entre vias de tráfego intenso; Parque São Jorge para estação de fundo, por estar distantes de fontes de emissão significativas e os bairros Porto dos Prades e Bockmann para estação comercial, por serem bairros com características comercias e de centralidade, nos quais se supõe haver intensa circulação de pedestres.<br>This study aimed to suggest locations for the monitoring of air quality in the city of Paranagua. For this, mathematical modeling of air pollutants dispersion was used, associated with the collection of information on population density and distribution of urban facilities in the city's neighborhoods. The concentration of different air pollutants (CO, NOX, SO2, PTS e HCT) on space and time were simulated using the modeling software AERMOD, considering vehicular, industrial and the Port of Paranagua emission. The meteorological data used in the simulations consisted of an hourly series of three years. The hourly maximum concentration to CO, NOX, SO2, PTS e HCT were 5572 μg m-3, 5741 μg m-3, 1539 μg m-3, 3368 μg m-3 e 247 μg m-3, respectively. The average concentration during the period considered to CO, NOX, SO2, PTS e HCT were 340 μg m-3, 343 μg m-3, 94 μg m-3, 116 μg m-3 e 38,6 μg m-3, respectively. For the installation of the air quality monitoring stations, the following neighborhoods were suggested: Alboit for industrial station, because it belongs to the Zone of Interest Port, which has potentially polluting activities; Coast for residential station due to its relative proximity to the port area; Vila Horizonte to serve station, to be located between high-traffic roads; Parque Sao Jorge to background station, to be far from significant emission sources and Port neighborhoods of Prades and Bockmann to commercial station because they are neighborhoods with commercial features and centrality, in which it is supposed be intense circulation of pedestrians.
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Blanco, Sánchez Marta. "Historia de vida temprana e inversión reproductiva de invertebrados bentónicos: integración al manejo y conservación a través de modelos de dispersión = Early life and reproductive investment of benthic invertebrates: integration to management and conservation throught dispersal models." Doctoral thesis, Universitat de Barcelona, 2019. http://hdl.handle.net/10803/666608.
Full textAbstract:
Las zonas costeras son uno de los ecosistemas que sufre mayor impacto antrópico a nivel mundial. La sobreexplotación de los recursos marinos es una de las actividades humanas que genera mayor impacto, reduciendo la abundancia y tamaño de las especies objetivo. Una de las medidas para proteger estos ecosistemas consiste en el establecimiento de áreas marinas protegidas. En Chile, el sistema actual de manejo de las pesquerías artesanales de especies bentónicas está basado en áreas parcialmente protegidas, las Áreas de Manejo y Explotación de Recursos Bentónicos (AMERBs), lo que ha supuesto una mejora en la sostenibilidad de una actividad de larga tradición en el país. Estas áreas entregan derechos de usos territoriales, conocidos mundialmente como TURF (sigla en inglés de Territorial Use Right for Fisheries). Sin embargo, actualmente estas áreas se gestionan de forma individualizada, de tal manera que la escala espacial de manejo no está acoplada a la escala de la dinámica de las poblaciones de invertebrados bentónicos. El objetivo de esta tesis es identificar áreas de alto valor para la producción, exportación y llegada de larvas en base a los patrones de historia de vida temprana, considerando variables y/o condicionantes relevantes de la fase adulta bentónica, como (a) la inversión reproductiva, (b) la densidad y talla de los adultos reproductores, variables determinantes de la distribución espacial de la producción de huevos y larvas, así como también variables que intervienen en la fase larval planctónica, como (c) los rasgos biológicos larvales, para acoplarlo con los patrones de circulación costera con el fin de contribuir a un mejor entendimiento de la dispersión y conectividad larval. Para este fin se seleccionaron dos especies relevantes social, comercial y ecológicamente: el erizo rojo (Loxechinus albus) y la lapa (Fissurella latimarginata). En primer lugar, se evaluó mediante muestreos de campo el efecto de la protección (relacionada con el régimen de explotación) y afloramiento costero sobre la inversión reproductiva y la condición individual de los adultos reproductores. Esta información sumada a los datos empíricos de distribución de tallas, densidad de individuos y fecundidad de las hembras reproductoras se utilizó para desarrollar un modelo de producción potencial de huevos en la costa central de Chile. Para el estudio del reclutamiento y dispersión se desarrolló un modelo biofísico de dispersión larvaria que permite evaluar el efecto de la variabilidad oceanográfica y los rasgos biológicos (migración vertical de las larvas y desarrollo dependiente de la temperatura) en la distancia de dispersión, el éxito del reclutamiento, y los patrones de conectividad larval. Los resultados sugieren que, para ambas especies, la protección y el afloramiento costero no tienen un efecto sobre la inversión reproductiva y la condición de los individuos. Sin embargo, la protección sí tuvo un efecto sobre la talla y densidad de individuos generando claros patrones espaciales de producción de gametos. Se observó que la variación geográfica y temporal de los procesos de circulación dominaneltransportey la dispersióndelas larvas enlaregión, independientemente de los rasgos biológicos evaluados. La mayoría del reclutamiento fue alóctono, con niveles bajos de auto-reclutamiento y retención local, incluso para la especie con un tiempo de vida planctónica corto (F. latimarginata). Los patrones geográficos de salida y llegada fueron similares para ambas especies, observándose una mayor importancia relativa de la región norte del dominio de estudio. Estos resultados permiten identificar los principales determinantes de la producción de huevos, el éxito del reclutamiento y la distancia de dispersión para dos especies de gran interés comercial en Chile, información que podría guiar recomendaciones para el manejo y la conservación en una de las regiones costeras más productivas pero también más explotadas del mundo.<br>Coastal zones are one of the ecosystems receiving higher anthropic impact. Fishing is a major source of human impact, reducing density and size of exploited species. Marine protected areas are one of the strategies established to control fishing impacts. The current artisanal fisheries management system in Chile is based on partially protected areas, TURFs (Territorial Use Right for Fisheries). This system enhances sustainability of one of the traditional activity in the country. However, these areas are individually managed so the scale of resource management is not coupled with the scale of exploited population dynamics. The objective of this thesis dissertation is to identify areas of high value for propagule production as well as source and sink areas based on early life history patterns, considering variables relevant for the adult phase such as (a) reproductive output,
(b) density and size of reproductive adults as both variables define the spatial distribution of eggs and larvae, as well as variables that affect the larval phase such as (c) larval biological traits, coupling these pieces of information with coastal circulation models to reach a better understanding of dispersal and larval connectivity. Two benthic invertebrates species exploited by artisanal fisheries
in Chile, the red sea urchin (Loxechinus albus) and keyhole limpet (Fissurella
latimarginata) were used as models. First, I evaluated the effect of protection and coastal upwelling on reproductive output and individual condition of reproductive adults. Based on size distribution, density of individuals and fecundity data I developed an egg production model along the central coast of Chile. Finally, I developed a biophysical larval dispersal model to assess the effect of oceanographic variability and larval biological traits (larval diel vertical migration and temperature-dependent larval development) on dispersal distance, recruitment success and connectivity patterns. These results showed that fishing regime and coastal upwelling did not affect individual reproductive output either individual condition for both species. However, fishing regime had an effect on size and density of individuals. I found that the geographic and temporal variation in circulation processes dominate transport and effective dispersal of larvae in the study region, regardless of larval biological traits. Most recruitment to local population was allochthonous, with low levels of self-recruitment and local retention even for the species with short planktonic larval duration. Similar geographic patterns of source and destination strengths were observed in both species, with the northern region of the studied domain showing relatively higher importance. These findings allow identifying primary determinants of recruitment success and dispersal distance for two important exploited species in Chile, and to provide the bases to advance recommendations for management and conservation in one the most productive, but also exploited, coastal regions in the world.
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Prudík, Jiří. "Model metropolitní optické sítě." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2008. http://www.nusl.cz/ntk/nusl-217666.
Full textAbstract:
The purpose of this master’s thesis is foremost to provide a simple guide how to build elements of optical metropolitan area network. The basic model consists to sequence of construction, network topology, passive and active parts. The collection contains examples of alternative technology such as Wireless LAN with different frequency. The optical network construction based on optical cable, fibres, splices, trays, adapters, connectors and active parts for example a lot of media convertor models. After that there are demonstrating type of wavelength division multiplexer used in metropolitan area network – passive planar PCL splitter. One of the passive planar splitter are used to increase optical fibre channel. At the end of the collection a simplified examples of used measurements – optical time domain reflectometry and optical fibre transmission. Contains standard protocols or reflectogram. The conclusion of this thesis summarizes costs of FTTb (Fibre To The Building) model of optical metropolitan area network in Czech republic and future contribution for society.
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Kano, Célia Hanako. "Modelagem e análise das cadeias de suprimentos globais e resilientes baseadas em rede de Petri." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/3/3152/tde-16062016-144200/.
Full textAbstract:
Em um cenário de aumento de competitividade, crescente expectativa por inovações do produto e necessidade de atender diferentes perfis de consumidores, o conceito de gerenciamento de cadeias de suprimentos globais (GSCM) surge como uma estratégia para coordenar mais eficazmente as atividades dispersas geograficamente dos sistemas produtivos. Na adoção do GSCM, as organizações devem lidar com rupturas que impactam no gerenciamento das suas atividades, tais como a interrupção de vias de transporte, pane no fornecimento de energia, desastres naturais e até ataques terroristas. Nesse contexto, o trabalho introduz um procedimento sistematizado para modelagem das cadeias de suprimentos visto como um sistema a eventos discretos e sua análise por simulação das atividades do GSCM baseada em técnicas formais como a rede de Petri (PN) e o Production Flow Schema (PFS). Um exemplo é também apresentado para ilustrar e comprovar as vantagens do método proposto na análise do GSCM.<br>In a context of increasing competition, rising of expectations for product innovations and need to satisfy different consumer needs, the concept of global supply chain management (GSCM) emerges as a strategy to more efficiently coordinate the geographically dispersed activities of production systems. Adopting GSCM, organizations have to deal with external disruptions that impact management activities, such as transport interruption, power supply failure, natural disasters and terrorist attacks. In this way, a systematized procedure for modeling supply chains as a discrete event system and simulation analysis of GSCM activities based on formal techniques, such as Petri net (PN) and Production Flow Schema (PFS) is introduced. An example is also presented to illustrate and confirm the advantages of the proposed method for GSCM analysis.
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Viljoen, Peter Martin. "Improving DWDM transmission systems by using dispersion management." Thesis, 2012. http://hdl.handle.net/10210/8238.
Full textAbstract:
M.Ing.<br>In this dissertation the emphasis falls on the use of the 1550 run WDM systems that make use of standard single-mode fibre. The reason for this is that more than 50 million kilometres of standard telecommunication fibre is already installed in the worldwide telephone network. Therefore, from an economical point of view, the fourth generation of lightwave systems has to make use of this existing base. Using single-mode fibre at high bit-rate (- 10 Gb/s) dispersion becomes a problem. Furthermore, if amplifiers are used, as in the case of long-haul WDM systems, non-linear effects also become important although the input power levels are low (-1 mW). Thus, the system performance is influenced by both the dispersion problem and fibre non-linearities. In this dissertation the influence of these effects was investigated and the use of different dispersion management schemes was considered in order to minimise the dispersion and the effects of these non-linearities on the optical signals. It was seen that by using pre-compensation, the optical pulses would become narrower whereas by using post-compensation, the pulses would be broader than the original input pulses. Thus, the combined effect of fibre non-linearity and fibre dispersion led to the fact that the order in which dispersion compensation is realised is important. By using symmetrical dispersion compensation that is defined as a dispersion compensation scheme that makes use of an equal amount of pre- and post-compensation sections, the tendency of pulse narrowing and pulse broadening can be balanced. It was found from simulations, that pre-compensation led to a smaller SPM penalty than postcompensation, whereas in the case of cross-phase ,modulation, the opposite is true. Using lumped dispersion compensation at the,en(f:o£ the system, it was found that both SPM and XPM penalties could be minimised. It was found that negative and positive lumped dispersion compensation could be used to improve the system perfortriance of pre- and post compensation schemes respectively. The performance of symmetrical compensation also improved by using a positive lumped dispersion compensation regarding SPM penalty, but in the case of XPM penalty, it was found that lumped dispersion compensation could not be used to improve this penalty. Furthermore, the effect of not using 100% dispersion compensation per span on the system performance was determined. From simulations, it followed that under-compensation will lead to an improvement in the system performances of the post- and symmetrical dispersion compensation, whereas an over-compensation will lead to an improvement in the precompensation case. It was also shown that XPM index penalty decreases in all of these dispersion compensation schemes if 100% compensation per span is not used. The reason for this is the inter -span walk-off that reduces the XPM distortion by reducing the localised buildup of phase distortions. Finally, it was shown that by independently controlling the input power levels in the SMF and DCF the best system performance is possible. Furthermore, by making use of lumped dispersion compensation or by not using 100% dispersion compensation per span, the system performance of the pre-, post- and symmetrical dispersion conipensation schemes can be improved quite a lot. Comparing the results of the pre-, post- and symmetrical dispersion compensation schemes that made use of independent control of power levels with the pre-, post- and symmetrical dispersion compensation schemes that did not use independent control ofpower levels, the Q factors were improved from 6.2 to 8, from 5.4 to 9 and from 7.5 to 11 in each case respectively.