Dissertations / Theses on the topic 'Laboratory Investigations for Fever'

The instabilities that occur at a sheared density interface are investigated in the laboratory, the Fraser River estuary and with Direct Numerical Simulations (DNS). In the laboratory, symmetric Holmboe instabilities are observed during steady, maximal two-layer exchange flow in a long channel of rectangular cross section. Internal hydraulic controls at each end of the channel isolate the subcritical region within the channel from disturbances in the reservoirs. Inside the channel, the instabilities form cusp-like waves that propagate in both directions. The phase speed of the instabilities is consistent with linear theory, and increases along the length of the channel as a result of the gradual acceleration of each layer. This acceleration causes the wavelength of any given instability to increase in the direction of flow. As the instabilities are elongated new instabilities form, and as a consequence, the average wavelength is almost constant along the length of the channel. In the Fraser River estuary, a detailed stability analysis is conducted based on the Taylor-Goldstein (TG) equation, and compared to direct observations in the estuary. We find that each set of instabilities observed coincides with an unstable mode predicted by the TG equation. Each of these instabilities occurs in a region where the gradient Richardson number is less than the critical value of 1/4. Both the TG predictions and echosoundings indicate the instabilities are concentrated either above or below the density interface. These ‘one-sided’ instabilities are closer in structure to the Holmboe instability than to the Kelvin-Helmholtz instability. Although the dominant source of mixing in the estuary appears to be caused by shear instability, there is also evidence of small-scale overturning due to boundary layer turbulence when the tide produces strong near-bed velocities. Many features of the numerical simulations are consistent with linear theory and the laboratory experiments. However, inherent differences be tween the DNS and the experiments are responsible for variations in the dominant wavenumber and amplitude of the wave field. The simulations exhibit a nonlinear ‘wave coarsening’ effect, whereby the energy is shifted to lower wavenumber in discrete jumps. This process is, in part, related to the occurrence of ejections of mixed fluid away from the density interface. In the case of the laboratory experiment, energy is transferred to lower wavenumber by the ‘stretching’ of the wave field by a gradually varying mean velocity. This stretching of the waves results in a reduction in amplitude compared to the DNS. The results of the comparison show the dependence of the nonlinear evolution of a Holmboe wave field on temporal and spatial variations of the mean flow.

Phase change of the water in the soil skeleton under cold climate conditions (also known as frost action in soils) affects soil properties and can be responsible for serious alterations in a soil body; causing damages (due to the volumetric expansion known as frost heave) to structures on or below the ground surface such as foundations, roads, railways, retaining walls and pipelines, etc. In order to improve the current design methods for roads against frost action, the Swedish Transport Administration (Trafikverket) has initiated a research program. The main goals of the program are to revise the existing frost heave estimation methods and improve the frost susceptibility classification system for subgrade soils. Literature was reviewed to gather the details of different freezing test equipment around the world and to identify common trends and practices for laboratory freezing tests. Based on the literature review and the collaboration with the University of Oulu, Finland an experimental apparatus was assembled for studying frost action in the laboratory. A detailed description of the experimental apparatus is given. Top to down freezing of specimens (of 10cm height and diameter) can be monitored while keeping track of water intake, vertical displacements (heave) and the temperature profile within the sample. Loads can be applied at the top of the sample to study the effects of overburden. Moreover, the test setup was modified with a camera system to have the option of recording the experiments. Disturbed samples of two different soil types were tested. Experiments with fixed and varying temperature boundary conditions were conducted to assess the validity of the assumptions for the frost heave estimation methods currently in use in Sweden. To this end, a qualitative relationship between frost heave and heat extraction rates based on theoretical equations was established. It was shown that there is a significant difference between the preliminary findings of the experimental work and the current system being used in Sweden to quantify heave. Image analysis techniques were used on two experiments that were recorded by the camera system. Image recording and correlation analyses provided detailed information about frost front penetration and ice lens formation(s) under varying temperature boundary conditions. Thawing has also been regarded in further studies. Results of the image analyses were compared to readings from conventional displacement measurements during the same test. Significant agreement between the results of image analyses and displacement measurements has been found. Image analysis was shown to be a viable method in further understanding of frost heave mechanisms. Shortcomings and disadvantages of utilizing the theoretical equations as well as the image analysis techniques were discussed. Potential remedies for overcoming the drawbacks associated with each approach are suggested. The work is concluded by discussing the potential improvements, planned upgrades (addition of pore pressure transducers) and the future experiments to be conducted.

In the presence of subgingival proximal margins, close to or below the cemento-enamel junction (CEJ), impression taking and adhesive luting procedures for indirect restorations are hampered; surgical crown lengthening or orthodontic eruption are viable options. However, the placement of a small amount of composite, so-called cervical margin relocation (CMR), was proposed as an alternative technique. To date, literature about CMR is scarce and the aim of this PhD thesis was to perform laboratory and clinical investigations to shed light on some crucial missing points. The thesis consists of 5 studies. The first study is a literature review summarizing the existing scientific literature on CMR technique performed prior to the adhesive cementation of indirect restorations. The second study is an in vivo randomized controlled clinical trial assessing the possible influence of CMR on periodontal health, after 12- month of clinical service. The third study is an in vitro study evaluating the marginal sealing of relocated mesio-occluso-distal overlays. The fourth study is an in vitro study analyzing the influence of cervical margin relocation and adhesive system on microleakage of indirect composite restorations. The fifth study is an in vitro study evaluating the possible correlation between two methodological approaches applied to evaluate cervical margin relocation. Different methodological approaches were used to perform the above-reported investigations, such as scanning electron microscopy (SEM) and microleakage analyses. The principal investigator was calibrated and trained before performing the operative procedures and laboratory investigations. All the recorded data were statistically analyzed with dedicated software. CMR is a relatively new restorative procedure and information on its performance is limited. Within the limitations of the performed laboratory and clinical studies, the present PhD thesis allowed to draw the following conclusions: 1. On the basis of the reviewed literature, currently, there is no strong scientific evidence that could either support or discourage the use of CMR technique prior to restoration of deep subgingival defects with indirect adhesive restorations; further randomized controlled clinical trials are necessary to provide reliable evidence on the influence of CMR technique on the clinical performance, especially on the longevity of restorations and periodontal health. 2. A higher incidence of bleeding on probing can be expected around teeth treated with CMR and in coincidence with deep margins placed at or closer than 2 mm from the bone crest; consequently, CMR should be considered as a clinically sensitive-technique, especially when performed on deep subgingival margins. 3. The marginal sealing ability of flowable and microhybrid resin composites is comparable for CMR; furthermore, luting overlays directly onto dentin without CMR appears to be a better method for limiting marginal leakage underneath CAD/CAM overlays. 4. CMR technique and the adhesive system employed for luting indirect restorations might represent a significant factor affecting microleakage at the interface below CEJ. 5. CMR seems to provide less adequate seal of the margin than the one achieved by cementing the restoration directly to dentin without CMR. The sealing ability of the marginal interface depends on the adhesive materials used for performing CMR. Differences in the quality of the marginal adaptation between two different materials used for CMR could not be detected by SEM observations. SEM examination of the marginal adaptation does not allow for the predictions of the functional sealing of the margins. Future in vitro and in vivo studies should evaluate the effectiveness of CMR technique and the marginal seal of different bonding systems and luting cements in combination with CMR. Particularly, randomized controlled clinical trials should investigate the durability of CMR and the response of periodontal tissues.

Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2016.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (pages 95-98).<br>Describing transport in fluid flows has been a long-standing challenge in dynamical systems theory, with applications to industrial and natural flows. The detection of Lagrangian structures that stay coherent over time helps gain insight into the evolution of a system's dynamics and the fate of transport. Whereas most techniques to detect coherent structures rely on a dense velocity field, techniques based on sparse datasets are increasingly being developed. The braid theory approach to detect Lagrangian coherent structures from sparse sets of trajectories is tested through a periodic, two-dimensional Stokes flow, the rotor-oscillator flow. Combined theoretical and numerical studies have shown that this flow can offer chaotic regimes with islands of coherence. The flow was recreated experimentally in a laboratory based on the findings of these theoretical studies. The braid theory approach was found to successfully detect coherent groups from sparse trajectories, although it is very sensitive to the quality of that data available.<br>by Margaux Filippi.<br>S.M.

The purpose of this research was to develop, implement and evaluate science investigation work based on a cognitive apprenticeship model of instruction and 'linked' to different assessment procedures. Data were gathered to evaluate the effects of the instruction and approaches to assessment on teachers and students, and on the development of students' investigation competency. Year 9 students performed six science investigations in which they examined a relationship between variables. Groups of three students worked together to choose the independent variable, plan their investigation, collect and analyse their data, and to evaluate their findings. The cognitive apprenticeship model of instruction included teacher modelling, coaching, scaffolding and fading, articulating and involving students in self-reflective and metacognitive practices. The three classes which participated in the study (n = 66) experienced different assessment regimes, teacher assessed and norm referenced, teacher assessed and criterion referenced and student assessed and criterion referenced assessment. The study was a naturalistic inquiry and data were collected from numerous sources including a pre and pastiest pencil and paper Test of Science Investigation Skills, pre and post test investigations in which students were assessed from their written responses on an Investigation Planning and Report Sheet, student questionnaires, teacher and student group interviews, and audio and video data. The qualitative data were summarised and interpreted as 76 assertions relating to the themes of the research; investigation competencies, the cognitive apprenticeship model of instruction and the assessment regimes. Sixteen general assertions which were considered to be more genera research findings were then formulated. Students' investigation competencies improved significantly as determined by their pre and post test performances on the Test of Science Investigation Skills, and by their performances on the Investigation Planning and Report Sheet. In addition to improving specific investigation competencies such as planning and conducting investigations, processing data and evaluating investigations, students also perceived that they improved social and workplace skills including working cooperatively, attending to detail, managing time and being organised. Difficulties students experienced in performing investigations were also identified. Based on improved students' performance, the cognitive apprenticeship model of instruction could be deemed as effective in teaching and learning science investigation competencies. As implemented in the study, weaknesses in the implementation of teacher modelling were exposed and it was suggested that modelling would be more beneficial if it were to occur in response to requests from students rather than at the behest of the teacher as an introduction to a learning activity. Classes experiencing teacher assessment, both norm referenced and criterion referenced, achieved similar gains in investigation competencies and the feedback to students following these assessments was similar in quality and quantity. Students in the student assessed criterion referenced class made more modest improvements in Planning investigations and Conducting investigations. These students lacked opportunities for high quality teacher feedback. Clearly these data need to be interpreted with caution because other factors in the learning milieu were not controlled. The implications arising from the research for classroom practice addressed factors contributing to science investigation competency, the cognitive apprenticeship model of instruction and the assessment of science investigations.

La perméabilité est une propriété essentielle notamment pour déterminer la nature explosive des volcans, ainsi que pour de nombreuses autres applications scientifiques et industrielles dans les environnements où l'écoulement du fluide est une préoccupation majeure. Combinant des méthodes expérimentales de déformation des roches en laboratoire, des approches de terrain, de la modélisation numérique, et des analyses systématiques de microstructure, ce travail a mis en évidence le caractère complexe de la formation et la destruction des réseaux poreux dans le magma et des roches volcaniques. La compétition entre les processus dilatants (qui augmentent la porosité) et compactants (qui la diminuent) exerce une influence sur les propriétés de transport des fluides à la fois dans le magma et dans la roche volcanique solidifiée. Ces processus incluent la vésiculation et la croissance des bulles dans le conduit, la rupture et la compression du magma, la fracturation issue du refroidissement et fracturation induite par le transport, ainsi que la déformation pendant ou après la mise en place des matériaux, et la densification par frittage<br>The permeability of various volcanic materials is an essential parameter governing the explosive behaviour of volcanic systems, as well as being important in many other scientific and industrial applications in environments where fluid flow is a major concern. Combining experimental rock deformation methods with field measurements, numerical modelling, and systematic analyses of rock microstructure, this work explores the complexities involved in the formation and destruction of porous networks in magma and volcanic rocks, addressing how permeability can evolve in volcanic systems. Competition between dilatant processes (which increase porosity) and compactant processes (which decrease porosity) influences the fluid transport properties both in the conduit-dwelling magma and in solidified edifice rock. These processes include (but are not limited to) vesiculation and bubble growth in the conduit, fracture and compaction of magma, post-emplacement thermal or mechanical fracturing, strain-induced deformation, and viscous sintering

A multi-disciplinary research project including experimental and modelling studies was carried out on shale samples to characterise their porosity and permeability. Pressure expansion techniques were used, including current industry-standard methods as well as new methods developed and modified throughout this research. The derived porosity and permeability values were cross-checked with the results from commercial laboratories. Finally, the results obtained were applied to a shale resource play currently being appraised to understand its commercial viability. Precise grain density results were achieved using the crushed shale method as helium is able to rapidly intrude small sample pores and is not significantly adsorbed onto the constituents of the shale. Precise bulk volume measurements were obtained using mercury immersion but these are ambient stress measurements and need correcting for in-situ conditions. Mercury probably does not enter the pore-space of shale at low pressures during MICP tests and instead closes artificial microfractures. So the results may provide a method to estimate bulk density at the reservoir stresses. The porosity measured using the crushed shale method is more accurate compared to core plug methods. It is important to dry crushed samples to standardise porosity measurements. Other laboratories produced comparable results except for one laboratory which most likely did not conduct sample cleaning procedures properly. Permeability values obtained using the crushed shale method were orders of magnitudes different between the measurements conducted during this study and commercial laboratories. Overall, this test appears to provide no useful information regarding the flow properties of shales. Measurements made on core plugs are often dominated by the presence of microfractures but it is possible to obtain reasonably reliable permeability estimates by inverting the experimental data using a dual porosity-permeability model. To assess the applicability of porosity and permeability methods on commercial shale play, a significant amount of in-situ field data (i.e. well tests, core data etc.) were gathered and tested during the collaborative project in Europe with a local gas exploration company. Gas-In-Place (GIP) and Estimated Ultimate Recovery (EUR) values were produced and based on these the project was approved by the company for the next stage of development. However the model constructed lacked the ability to reproduce the well flow production rates.

Thesis (M.S.)--Michigan State University. Interdepartmental Biological Sciences, 2008.<br>Title from PDF t.p. (viewed on Aug. 3, 2009) Includes bibliographical references (p.166-168). Also issued in print.

Tidal meandering channels are ubiquitous features of tidal landscapes and play a fundamental role on the eco-morphodynamic evolution of these environments. However, only a handful of papers provide details on tidal meander planimetric shape, morphometric characteristics and morphodynamic evolution, and the internal achitecture of tidal meanders has not been explored in detail. Moreover, the morphodynamic evolution of tidal meanders and the related sedimentary products have often been interpreted on the basis of the well developed models and theories existing for their fluvial counterparts, despite a number of differences were a priori identifiable. Toward the goal of improving current understanding of the morphodynamic evolution of tidal meanders, five main issues have been investigated in the present work: i) rates of migration and evolutionary dynamics of tidal meanders; ii) assessment and quantification of differences and analogies existing between the planform features of tidal and fluvial meanders; iii) variations of tidal meander hydrodynamics in response to different tidal phases, and the role that these variations exert on tidal meander sedimentary products; iv) role played by bidirectional flows, tidal asymmetries and lateral tributaries; v) assessment of influence of tide amplitude, basin slope and initial shoreline configuration on tidal channel network ontogeny and evolution via laboratory experiment. A multidisciplinary approach has been adopted, with different methodologies encompassing remote sensing techniques, field observations, numerical modelling and physical-laboratory experiments. Activities have been carried out in parallel with sedimentological studies, in order to provide a comprehensive framework. The main results from this work highlighted that: I) once conveniently scaled with channel width, tidal meander migration rates are very similar to those displayed by fluvial meanders, thus challenging the paradigm of tidal meanders as a stable landscape features; II) differences and analogies between tidal and fluvial meander planforms can be addressed in a quantitative way, and different metrics exist thta allow one to successfully quantify these differences; III) strong asymmetries exist between different tidal phases, exerting a crucial role on the depositional patterns of tidal meanders; IV) under certain conditions, lateral tributaries can strongly influence the evolution of bends modifying local mechanisms of flow and sediment distribution; V) tidal channel network features evolve differently in response to different tidal ranges, basin slopes and relative sea level changes, whereas the number of breaches along the initial shoreline seems to have little effect on the evolution of the network itself.<br>Le reti di canali meandriformi costituiscono una delle principali componenti dei sistemi mareali, e giocano un ruolo di fondamentale importanza nell’evoluzione eco-morfodinamica di questi ambienti. Tuttavia, solo un numero limitato di studi scientifici ne ha analizzato le configurazioni planimetriche, le caratteristiche morfometriche e l’evoluzione morfodinamica. Inoltre, l’evoluzione morfodinamica e i prodotti sedimentari dei meandri a marea sono spesso stati interpretati sulla base di teorie e modelli sviluppati per i loro omologhi fluviali, nonostante numerose differenze tra le due tipologie siano identificabili a priori. Nell’intento di comprendere più approfonditamente l’evoluzione morfodinamica dei meandri a marea, nel presente lavoro sono stati studiati 5 differenti argomenti: i) tassi di migrazione e dinamiche evolutiove dei meandri a marea; ii) stima e quantificazione delle differenze planimetriche esistenti tra meandri fluviali e tidali; iii) variazioni dell’idrodinamica dei meandri a marea in risposta all’alternanza delle fasi mareali, e influenza di queste variazioni sui prodotti sedimentari propri dei meandri a marea; iv) ruolo della bidirezionalità del flusso, delle asimmetrie mareali e dei tributari laterali; v) stima dell’influenza dell’ampiezza di marea, delle pendenze topografiche del bacino tidale e della configurazione iniziale della linea di costa sulla nascita ed evoluzione morfologica delle reti di canali a marea. Nelle suddette analisi é stato utilizzato un approccio di tipo multidisciplinare, combinando metodologie quali remote-sensing, osservazioni in situ, modellazione numerica ed esperimenti su modelli fisici. Le attività sono state condotte in parallelo con studi sedimentologici, così da fornire un quadro che fosse il più esaustivo possibile. I principali risultati ottenuti evidenziano che: I) se convenientemente normnalizzati con la larghezza del canale, i tassi di migrazione dei meandri a marea sono molto simili a quelli dei loro corrispettivi fluviali, inficiando così il paradigma che vede i meandri tidali come un’entità morfologica essenzialmente stabile; II) le differenze tra meandri tidali e fluvali non sono solo qualitative, e diverse sono le metriche che possono essere utilizzate per quantificare queste differenze; III) le asimmetrie tra le diverse fasi di marea sono significative, e influenzano i patterns deposizionali in modo determinante; IV) gli affluenti laterali possono influenzare fortemente l’evoluzione dei meandri, modificando i meccanismi locali di distrubuzione dei flussi e dei sedimenti; V) le reti di canali a marea evolvono in modo diverso in risposta a differenti ampiezze di marea, pendenze del bacino tidale e cambiamenti del livello relativo del medio mare, mentre la configurazione iniziale della linea di costa non sembra avere effetti significativi sull’evoluzione della rete stessa.

The aim of this thesis is to understand if cyanobacteria, grown on an Earth-like planet orbiting around the habitable zone of an M star can survive and use the light coming from the star in a fruitful way, in particular analyzing their gaseous by-products. The organisms chosen usually don't have photopigments capable to photosynthesize the NIR part of the radiation, but can modify their photosynthetic apparatus in order to adapt to different light conditions if exposed in NIR light conditions, producing chlorophyll d and f. The two bacteria highlighted for our purpose are Chlorogloeopsis fritschii and Cyanobacterium Aponinum. The first is known to be able to change its photosynthetic apparatus to cope with new radiation conditions. In particular is capable to generate chlorophyll d and f if exposed to NIR light (720 nm). This feature is call FarLip acclimation. The second bacterium is a well known bacterium but no one has ever tried to understand if it has the same capability. Efforts have been done in order to find the best culture medium and the best growth conditions of temperature and pH. In order to understand how photosynthetic life can handle different radiation doses we ideated and realized a novel and pioneering LED radiation source with dynamical features. Its wavelength intervals (365nm-940nm) overlap the limits of photosynthetic pigment absorption range (280-850 nm) of most common photosynthetic bacteria. Our simulator is composed by an array of 25 different channels corresponding to 25 different wavelengths. Each channel can host a maximum of about 15 LEDs. This simulator has been built thinking to modularity. In fact it is endowed by a mosaic of circuit boards arranged in a pie-chart shape, on the surface of which will be welded the LEDs. This solution allows a rapid change of the damaged LEDs and an easy implementations with other wavelengths. This simulator is capable to reproduce the spectra of main sequence F, G, K and M stars as well as the most common commercial lamps within its wavelength intervals. The control system is composed by a Laptop which controls a LED box and an STS-VIS spectrograph from Ocean Optics with cosine corrector. The first system generate the best fit of the input spectrum and give information to the simulator on how to reproduce it. The spectrometer has the task to control the goodness of the fit and, by means of a closed loop system, to adjust it tuning the LED's power in real time. The stellar simulator bas been subjected to several tests. The power emanated from the radiation source has been estimated to be 106.22 W while the thermal power has been calculated to be 434.05 W. The stellar simulator have been characterized in flux, analyzing the radiation at different distances from the device, from the exit of the source up to 25 cm. Then uniformity measurements have been done, analyzing the flux on a distance of 6.5 cm from the centre. Finally, I calculated the absorption of the optics of the radiation source analyzing the spectra coming out from the stellar simulator and compared it with respect to the spectrum of the single LEDs. In order to lodge the bacteria we built new concept incubator made of a stainless steel cell with the potential to flux a desired gaseous mixture inside it and fill the cell with the desired gas mixture. Four wedged optical windows opens on the lateral surface and needs to allow the oxygen and carbon dioxide concentration inside by means of a Tunable Diode Laser Absorption Spectroscopy (TDLAS) system. The cell is topped by a BOROFLOAT uncoated window to collect the light from the stellar simulator. The cell has been characterized in void and oxygen and carbon dioxide detecting limits have been found. During the experiment, bacteria have been grown in white light conditions at for 24 days at 20 micromol photons/m^2/s and at 30°C in order to understand the growth times and the behaviour in optimal conditions. After that, a new growth experiment have been performed by growing both cyanobacteria species at 30°C and 20 micromol photons/m^2/s and oxymetric measurements have been done after 6 days from the culture start, thus during their exponential growth phases. Then, for the main part of the experiment, eight samples have been used. Two samples of Cyanobacterium aponinum have been grown at 20 micromol photons/m^2/s in white light for 6 days and then at 100 micromol photons/m^2/s for the residual 3 days in white light. Two samples of Chlorogloeopsis fritschii have been grown at 20 micromol photons/m^2/s for 6 days in white light and then at 100 micromol photons/m^2/s for the residual 3 days in white light. Two samples of Cyanobacterium aponinum have been grown at 20 micromol photons/m^2/s for 6 days in white light and then at 100 micromol photons/m^2/s for the residual 3 days using the radiation spectrum of an M7 type star. Two samples of Chlorogloeopsis fritschii have been grown at 20 micromol photons/m^2/s for 6 days in white light and then at 100 micromol photons/m^2/s for the residual 3 days using the radiation spectrum of an M7 type star. The temperature has been kept at 30°C for the samples not exposed to M7 light and at a temperature oscillating from 35°C to 38°C for the samples exposed to M7 light. The higher environmental temperature under the stellar simulator has been due to the over-heating of the LEDs. During the 3 days of different exposure measurements of optical density have been done in order to collect data about the different growth curves. Moreover, O2 production have been calculated for each sample. Finally, a chromatic response have been done, in order to understand if the colour would reflect the vitality of the bacteria<br>Lo scopo di questa tesi è quello di capire come dei cianobatteri, cresciuti su un pianeta di tipo terrestre orbitante attorno alla zona di abitabilità di una stella M possano sopravvivere ed usare la luce proveniente dalla stella stessa in modo fruttuoso per la loro esistenza. In particolare ci focalizzeremo sullo studio dei gas da essi prodotti. Gli organismi scelti non hanno pigmenti in grado di fotosintetizzare la parte NIR dello spettro di radiazione, ma riescono a modificare il loro apparato fotosintetico per far fronte alle nuove condizioni di luce, se esposti a luce NIR, producendo clorofilla d ed f. I due batteri scelti per i nostri esperimenti sono Chlorogloeopsis fritschii e Cyanobacterium Aponinum. Il primo batterio è certamente in grado di variare il suo apparato fotosintetico in differenti situazioni luminose. In particolare è in grado di produrre clorofilla e ed f se esposto a luce NIR (720 nm). Questa proprietà si chiama acclimatamento FarLip. Il secondo batterio è è abbastanza noto ma non è stata ancora studiata la sua predisposizione a questo tipo di pratica. Per questi batteri sono stati ricercati i terreni di coltura, di temperatura e pH che meglio permettessero il loro sviluppo. Per capire come il foto-acclimatamento possa aver luogo abbiamo ideato e realizzato un nuovo tipo di sorgente a LED con peculiarità dinamiche. L'intervallo di lunghezze d'onda che copre (365nm-940nm) si sovrappone ai limiti di assorbimento dei pigmenti fotosintetici (280-850 nm) dei più comuni batteri. Il simulatore è composto da 25 differenti canali corrispondenti a 25 differenti lunghezze d'onda. Ogni canale può ospitare un massimo di 15 LED. Il simulatore come detto è stato concepito secondo il concetto di modularità. Infatti è composto da un mosaico di piastre in corma circolare divisa a spicchi e su ognuna di tali piastre sono saldati i LED. Questa soluzione permette di cambiare rapidamente i LED danneggiati e permette una facile implementazione con altre lunghezze d'onda. Il simulatore stellare è in grado di riprodurre lo spettro di varie stelle di sequenza principale, F, G, K e M e molte delle più comuni lampade. Il sistema di controllo è composto da un PC che ha il compito di gestire i LED e da uno spettrometro con relativo correttore di coseno che STS-VIS della ditta Ocean Optics. Il PC genera il miglior fit dello spettro da ricreare con l'illuminatore e lgi da informazioni su come riprodurlo. Lo spettrometro invece controlla la bontà del fit ed attraverso un sistema a circuito chiuso, regola la luminosità dei LED in tempo reale. Abbiamo fatto dei test per verificare il corretto funzionamento del simulatore e stimato la potenza totale emanata, 106.22 W e quella termica, 434.05 W. Inoltre la nostra sorgente di radiazione è stata caratterizzata in flusso, analizzando la radiazione a diverse distanze, dalla bocca di apertura fino a 25 cm da essa. Poi sono state fatte misure di uniformità del flusso entro 6.5 cm dal centro. Infine è stato calcolato l'assorbimento dovuto alle ottiche frapposte fra i LED e i campioni. Per alloggiare i batteri abbiamo ideato e costruito in incubatore in acciaio inox con la possibilità di avere un continuo flussaggio di gas o di essere riempita con una miscela desiderata. Sui lati si aprono quattro finestre ottiche che servono per permettere la misura di concentrazione di ossigeno e di anidride carbonica all'interno attraverso un sistema laser chiamato Tunable Diode Laser Absorption Spectroscopy (TDLAS). L'incubatore è dotato anche di una finestra superiore in borosilicato per permettere alla luce di entrarvi. La cella è stata caratterizzata termicamente e sono stati calcolati le quantità minime osservabili sia di ossigeno che di anidride carbonica. Durante la prima fase dell'esperimento, i batteri selezionati sono stati fatti crescere per 24 giorni Durante l'esperimento, i batteri sono stati fatti crescere a 24 days at 20 micromol fotoni/m^2/s e a 30 °C per costruire le curve di crescita ed il loro comportamento in condizioni ottimali. Dopo ciò, è stato condotto un secondo esperimento facendo crescere entrambe se specie di cianobatteri a 30°C e 20 micromol fotoni/m^2/s in luce bianca ed acquisendo dopo 6 giorni le misure di produttività di ossigeno durante la fase esponenziale. Passati sei giorni sono stati ripartite otto colture, quattro di Cyanobacterium aponinum e quattro di Chlorogloeopsis fritschii. Due colture di Cyanobacterium aponinum sono state fattie crescere prima a micromol fotoni/m^2/s per sei giorni e poi a 100 micromol fotoni/m^2/s per altri tre giorni, sempre in luce bianca. La stessa cosa è stata fatta per due campioni di Chlorogloeopsis fritschii. Due colture di Cyanobacterium aponinum sono state fattie crescere prima a micromol fotoni/m^2/s per sei giorni e poi a 100 micromol fotoni/m^2/s per altri tre giorni,con una radiazione che simulava quella di una stella di tipo M7 incidente su un pianeta terrestre. La stessa cosa è stata fatta per Chlorogloeopsis fritschii. La temperatura è stata mantenuta a 30°C per i campioni in luce bianca e fra 35°C e 38°C per gli esemplari illuminati con luce M7. La maggior temperatura nel secondo caso è stata dovuta al calore prodotto dai LED. Durante i tre giorni in cui i campioni sono stati sottoposti a 100 micromol fotoni/m^2/s sono state prese misure di densità ottica e calcolate le curve di crescita. Inoltre per ogni campione è stata calcolata la produzione di ossigeno. Infine i campioni sono stati analizzati anche dal punto di vista del cromatismo per capire come il loro colore fosse collegato alla vitalità

The structural behaviour of pavements in cold regions can considerably be affected by seasonal variation in environmental factors such as temperature and moisture content. Along with the destructive effect of heavy traffic loads, climatic and environmental factors can considerably contribute to pavement deterioration. These factors can influence the structural and functional capacity of the pavement structures which, as a result, can trigger and accelerate pavement deterioration mechanisms. Studies on the influence of variation of the environmental factors on the response and behaviour of pavement materials have shown that proper consideration to these factors must be given in realistic pavement design and analysis. In flexible pavement structures, particularly with a thin hot mix asphalt (HMA) layer, unbound materials and subgrade soil largely contribute to the overall structural behaviour of the pavement system. In unbound materials, moisture content and its variation can significantly affect pavement layer stiffness and permanent deformation characteristics. Therefore, the moisture condition of pavements and its influence on the mechanical behaviour of pavement materials has been of interest among the pavement research community. A proper understanding of moisture transformation in pavement systems and its effects on pavement performance are important for mechanistic pavement design. The present summary of this doctoral thesis is based on four main parts. The first part of the thesis covers field measurements and findings from a test section along county road 126 in southern Sweden and consists of two journal papers (paper I and II) tackling different aspects of the research topic. This test section is located in a relatively wet ground condition and consists of a thin flexible pavement structure with a deep drainage system. It is instrumented with subsurface temperature, volumetric moisture content and groundwater probes. The mechanical response of the pavement structure was investigated using Falling Weight Deflectometer (FWD) measurements. The second part of the thesis (paper III and IV) are based on laboratory experiments and investigates different recent approaches that have been proposed to apply principles of unsaturated soil mechanics for incorporating seasonal variation of moisture content into the resilient modulus models using matric suction. The third part of the thesis (paper V) builds a bridge that spans between the laboratory and field investigations with an attempt to evaluate one of the predictive models presented in Paper III. The fourth part of the thesis (paper VI) mainly focuses on the laboratory-based investigation of the permanent deformation characteristic of subgrade soils. In this part, the permanent deformation characteristics of two different silty sand subgrade soils were investigated and modelled using the data obtained from repeated load traxial tests. Paper I mainly focuses on the spring-thaw weakening of the pavement structure. The environmental data collected using different sensors and the FWD tests were used to investigate variations in moisture content with thaw penetration and its influence on the stiffness of unbound layers and the pavement’s overall bearing capacity. Using the backcalculated layer stiffness and corresponding in situ moisture measurements in the unbound layers, a degree of saturation-based moisture-stiffness model was developed for the granular material and the subgrade. In Paper II, the drainage system of the structure was manually clogged during a three month period in summer to raise the groundwater level and increase the moisture content of the layers. Along with the subsurface groundwater level and moisture content monitoring, the structural response of the pavement was studied. In this research work, the FWD tests were conducted at three different load levels. The stress dependent behaviour of the unbound granular layer and the subgrade soil were further studied using the multilevel loads FWD test data. Additionally, parameters of a nonlinear stress-dependent stiffness model were backcalculated and their sensitivity to in situ moisture content was studied. In Paper III and IV, series of suction-controlled repeated load triaxial (RLT) tests were conducted on two silty sand (SM) subgrade materials. Several resilient modulus prediction models that account for seasonal moisture content variation through matric suction were summarized and after optimizing the model parameters, the capability of the prediction models in capturing the material response were evaluated. In Paper V, an attempt was made to evaluate the proficiency of one of the suction-resilient modulus models using the field moisture content and FWD measurements from the Torpsbruk test site. The backcalculated subgrade stiffness dataset at different moisture contents were compared with resilient modulus models obtained from the suction-resilient modulus predictive model. Paper VI presents an evaluation of several permanent deformation models for unbound pavement materials that incorporate the time-hardening concept using a series of multistage repeated load triaxial (RLT) tests conducted on silty sand subgrade materials. The permanent deformation tests were conducted at four different moisture contents with pore suctions measurement throughout the test. The effect of moisture content (matric suction) on the permanent deformation characteristics of the materials and the predictive model parameters were further investigated.<br><p>QC 20150324</p>

Two sets of related experiments are presented here. In the first, measurements of shear Alfvén waves are used to test the predictions of a variety of different electron collision operators, including several Krook collision operators as well as a Lorentz collision operator. New expressions for the collisional warm-plasma dielectric tensor resulting from the use of the fully-magnetized collisional Boltzmann equation are presented here. Theoretical predictions for the parallel phase velocity and damping as a function of perpendicular wave number k⊥ are derived from the dielectric tensor. Laboratory measurements of the parallel phase velocity and damping of shear Alfvén waves were made to test these theoretical predictions in both the kinetic (vte ≫ vA) and inertial (vte ≪ vA) parameter regimes and at several wave frequencies (ω < ωci). Results show that in the inertial regime, the best match between measurements and theory occur when any of the Krook operators are used to describe electron collisions. In contrast, the best agreement in the kinetic regime is found when collisions are completely ignored. In the second set of experiments, whistler waves were launched and received by a pair of dipole antennas immersed in the plasma at two positions along the background magnetic field. According to cold-plasma theory, there is absorbtion of the whistler wave when ω = |ωce| = eB/me due to resonance with the electrons. The whistler frequency was swept from somewhat below up to the electron cyclotron frequency |ωce|. As the frequency was swept, the wave was resonantly absorbed by those parts of electron phase space density which were Doppler shifted into resonance. The transmission of the wave through the plasma was measured. This measurement of transmission can be converted into a measure of the parallel electron distribution function. This diagnostic is designed to attempt to measure modifications to the parallel electron distribution function due to interactions with inertial Alfvén waves.

Enteric fever caused by Salmonella enterica serovars Typhi and Paratyphi A are a major public health concern in Kathmandu. The aim of this thesis was to identify and assess the population most at risk by investigating epidemiologic trends of enteric fever within a subset population of Kathmandu. Therefore,the burden and incidence of enteric fever within the study population and the seasonal and gender distribution of enteric fever was assessed. Considerable burden of enteric fever, unrelated to population density, correlating with the seasonal fluctuations in rainfall was observed. This thesis also aimed to improve the understanding of enteric fever transmission by identifying probable transmission routes,hence various water and food samples were analysed and the extent of faecal contamination in them was determined. S. Typhi isolates were sequenced and genotyped and combined with GPS data to longitudinally study the local distribution and infer transmission of this human restricted bacterial pathogen. Extensive clustering of typhoid independent of population size and density and existence of an extensive range of genotypes within typhoid clusters including individual households with multiple cases was observed. These observations predict that indirect transmission had an overwhelming contribution for disease persistence, potentially through contaminated water. Consistent with this hypothesis, S. Typhi and S. Paratyphi A were detected in water supplies and it was observed that typhoid was spatially associated with public water sources and low elevation. A concurrent case-control study was also conducted which allowed for the determination of risk factors in the population at risk. These studies imply that resources should be allocated toward controlling the most important vectors of enteric fever, including food sold by vendors, chlorination of drinking water, construction of proper water distribution and sewage networks,vaccination campaigns and hygiene education.

<p>Achievement data from the 3<i>rd</i> International Mathematics and Sciences Study and Program for International Student Assessment in science have indicated that Black students from economically disadvantaged families underachieve at alarming rates in comparison to White and economically advantaged peer groups. The study site was a predominately Black, urban school district experiencing underachievement. The purpose of this correlational study was to examine the relationship between students&rsquo; use of inquiry-based laboratory investigations and their performance on the Biology End of Course Test, as well as to examine the relationship while partialling out the effects of student gender. Constructivist theory formed the theoretical foundation of the study. Students&rsquo; perceived levels of experience with inquiry-based laboratory investigations were measured using the Laboratory Program Variable Inventory (LPVI) survey. LPVI scores of 256 students were correlated with test scores and were examined by student gender. The Pearson correlation coefficient revealed a small direct correlation between students&rsquo; experience in inquiry-based laboratory investigation classes and standardized test scores on the Biology EOCT. A partial correlational analysis indicated that the correlation remained after controlling for gender. This study may prompt a change from teacher-centered to student-centered pedagogy at the local site in order to increase academic achievement for all students. The results of this study may also influence administrators and policy makers to initiate local, state, or nationwide curricular development. A change in curriculum may promote social change as students become more competent, and more able, to succeed in life beyond secondary school. </p>

Thesis (Ph. D.)--Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2010.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references.<br>This thesis presents the results of four discrete investigations into processes governing the organic and inorganic chemical composition of seafloor hydrothermal fluids in a variety of geologic settings. Though Chapters 2 through 5 of this thesis are disparate in focus, each represents a novel investigation aimed at furthering our understanding of subsurface geochemical processes affecting hydrothermal fluid compositions. Chapters 2 and 3 concern the abiotic (nonbiological) formation of organic compounds in high temperature vent fluids, a process which has direct implications for the emergence of life in early Earth settings and sustainment of present day microbial populations in hydrothermal environments. Chapter 2 represents an experimental investigation of methane (CH4) formation under hydrothermal conditions. The overall reduction of carbon dioxide (C02) to CH4, previously assumed to be kinetically inhibited in the absence of mineral catalysts, is shown to proceed on timescales pertinent to crustal residence times of hydrothermal fluids. In Chapter 3, the abundance of methanethiol (CH3SH), considered to be a crucial precursor for the emergence of primitive chemoautotrophic life, is characterized in vent fluids from ultramafic-, basalt- and sediment-hosted hydrothermal systems. Previous assumptions that CH3SH forms by reduction of CO2 are not supported by the observed distribution in natural systems. Chapter 4 investigates factors regulating the hydrogen isotope composition of hydrocarbons under hydrothermal conditions. Isotopic exchange between low molecular weight n-alkanes and water is shown to be facilitated by metastable equilibrium reactions between alkanes and their corresponding alkenes, which are feasible in natural systems. In Chapter 5, the controls on vent fluid composition in a backare hydrothermal system are investigated. A comprehensive survey of the inorganic geochemistry of fluids from sites of hydrothermal activity in the eastern Manus Basin indicates that fluids there are influenced by input of acidic magmatic solutions at depth, and subsequently modified by variable extents of seawater entrainment and mixing-related secondary acidity production.<br>by Eoghan Reeves.<br>Ph.D.

Thesis (Ph.D.)--Indiana University, School of Public and Environmental Affairs, 2008.<br>Title from PDF t.p. (viewed on May 13, 2009). Source: Dissertation Abstracts International, Volume: 69-08, Section: B, page: 4637. Adviser: Philip S. Stevens.

Thesis (M. S.)--Mechanical Engineering, Georgia Institute of Technology, 2005.<br>Berthelot, Yves, Committee Member ; Cunefare, Kenneth A, Committee Chair ; Lynch, Christopher, Committee Member. Includes bibliographical references.

Achievement data from the 3rd International Mathematics and Sciences Study and Program for International Student Assessment in science have indicated that Black students from economically disadvantaged families underachieve at alarming rates in comparison to White and economically advantaged peer groups. The study site was a predominately Black, urban school district experiencing underachievement. The purpose of this correlational study was to examine the relationship between students' use of inquiry-based laboratory investigations and their performance on the Biology End of Course Test, as well as to examine the relationship while partialling out the effects of student gender. Constructivist theory formed the theoretical foundation of the study. Students' perceived levels of experience with inquiry-based laboratory investigations were measured using the Laboratory Program Variable Inventory (LPVI) survey. LPVI scores of 256 students were correlated with test scores and were examined by student gender. The Pearson correlation coefficient revealed a small direct correlation between students' experience in inquiry-based laboratory investigation classes and standardized test scores on the Biology EOCT. A partial correlational analysis indicated that the correlation remained after controlling for gender. This study may prompt a change from teacher-centered to student-centered pedagogy at the local site in order to increase academic achievement for all students. The results of this study may also influence administrators and policy makers to initiate local, state, or nationwide curricular development. A change in curriculum may promote social change as students become more competent, and more able, to succeed in life beyond secondary school.

When a product performs better or worse than expectations, there are many biological, ecological, and operational factors that must be examined. Genetic resistance to the pesticide itself is often a concern. The control interval depends on the ecological impact of biotic (e.g., presence and function of natural enemies) and abiotic (e.g., frequency and severity of storms) factors. Timing, rates, and application methods used are also key factors affecting product performance. A four-year study to evaluate pyriproxyfen (Knack®) field performance in Arizona was initiated in 2004, after levels of whitefly susceptibility in statewide surveys were observed to be decreasing. Grower sites in Maricopa, Buckeye, Wellton, and Marana were used. We controlled for major operational factors by using a common timing, rate, and aerial application for each Knack spray. Resistance bio-assays were conducted on progeny of field-collected adults, pre- and post-spray. New eggs were marked in-field prior to spraying and examined in the field and lab in order to isolate Knack-associated mortality caused by direct toxicity as well as by ecological factors (e.g., bioresidual). Nymphal bioassays were used to evaluate metamorphosis inhibition. Population trends were estimated using standard sampling methods. Appropriate check plots were compared to the Knack treatment. Study results suggest Knack field performance and pyriproxyfen resistance has not changed significantly among the years or locations examined to date. In 2005, many struggled to gain control over whitefly populations. This work indicated that Knack performance and resistance parameters were within the range expected for the last several years. However, operational and ecological barriers to the performance of Knack and other chemistry were in play. Late planted conditions, lush winter vegetation capable of hosting whiteflies, poor growing conditions, and an extended period of extreme immigration pressure were all factors that diminished the impact of Knack and other products in 2005. In contrast, the winter preceding 2006 was among the driest on record followed by a very active monsoon season in central Arizona. High winds and dust movement, and a very active natural enemy community helped to continually lower whitefly populations. The result was a whitefly season characterized as light, with overall foliar insecticide usage setting a 28-yr record low for Arizona cotton. Barring all other operational and ecological factors at work, control intervals should have been similar each year. Yet, observed intervals have been different (e.g., 2005 vs. 2006) and point to the importance of these external factors in assessing product performance. Work will continue in 2007 to identify factors that contribute to whitefly outbreak conditions. These data will be key to understanding any performance changes, either due to operational or ecological factors mentioned above or due to innate changes in whitefly susceptibility. This will be important in advising growers about the risk factors associated with whitefly outbreaks and should lead to recommendations for minimizing these risks.

<p>Optical coherence tomography is an imaging modality with an outstanding resolution. During the project, a time domain OCT system based on a Michelson fibre interferometer was implemented and put into operation. A super-luminescent diode with a centre wavelength of 1295nm and a bandwidth of 45nm was selected as light source and a linear variable delay line as reference. Basic tests were made on phantoms constructed of filter foils and on gel-like agar slices with optical properties similar to human tissue. It was shown that the achievable resolution was at least 36um and can be increased. The system can easily be enhanced to create two-dimensional images.</p><br><p>Optische Kohärenztomographie ist ein bildgebendes Verfahren mit einer hervorragenden räumlichen Auflösung. Im Laufe des Projekts wurde ein OCT-System basierend auf einem faseroptischen Michelson-Interferometer implementiert und in Betrieb genommen. Als Lichtquelle wurde eine Superlumineszenzdiode mit einer Mittenwellenlänge von 1295nm und einer Bandbreite von 45nm gewählt. Eine variable optische Verzögerungsleitung diente als Referenz. Erste Messungen an Filterfolien und gelähnlichen Agarphantomen, die die optischen Eigenschaften von menschlichem Gewebe nachbildeten, lieferten eine räumliche Auflösung von mindestens 36um. Durch die modulare Bauweise ist das System leicht für zweidimensionale Aufnahmen erweiterbar.</p>