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Mölders, Nicole, and Gerd Tetzlaff. "Betrachtungen zur Heterogenität." Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-213706.
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Es wird aufgezeigt, wie durch die Notwendigkeit, in (Chemie-Transport-)Modellen diskretisieren zu müssen, die natürliche Heterogenität einer Landschaft bei der Modellierung reduziert wird. Es wird ein Maß definiert, mit dessen Hilfe die Heterogenität eines Gebiets, z.B. einer Gitterzelle erfaßt werden kann. Das Maß erlaubt auch, unterschiedliche Gebiete bezüglich ihrer Heterogenität zu vergleichen. Es bezieht sowohl den Wechsel von Flächen unterschiedlicher Landnutzung als auch die Anzahl der Ökosysteme einThe loss of information due to discretization is illustrated. A measure is defined that allows to characterize the degree of heterogeneity of an area, for instance a grid cell, with respect to the boundaries between areas of different landuse as well as the amount of ecosystems. lt also allows to compare different landscapes with respect to their heterogeneity
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Mölders, Nicole, and Gerd Tetzlaff. "Betrachtungen zur Heterogenität." Wissenschaftliche Mitteilungen des Leipziger Instituts für Meteorologie ; 12 = Meteorologische Arbeiten aus Leipzig ; 4 (1999), S. 1-9, 1999. https://ul.qucosa.de/id/qucosa%3A15091.
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Es wird aufgezeigt, wie durch die Notwendigkeit, in (Chemie-Transport-)Modellen diskretisieren zu müssen, die natürliche Heterogenität einer Landschaft bei der Modellierung reduziert wird. Es wird ein Maß definiert, mit dessen Hilfe die Heterogenität eines Gebiets, z.B. einer Gitterzelle erfaßt werden kann. Das Maß erlaubt auch, unterschiedliche Gebiete bezüglich ihrer Heterogenität zu vergleichen. Es bezieht sowohl den Wechsel von Flächen unterschiedlicher Landnutzung als auch die Anzahl der Ökosysteme ein.The loss of information due to discretization is illustrated. A measure is defined that allows to characterize the degree of heterogeneity of an area, for instance a grid cell, with respect to the boundaries between areas of different landuse as well as the amount of ecosystems. lt also allows to compare different landscapes with respect to their heterogeneity.
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Babayan, Anna [Verfasser], and Klaus [Akademischer Betreuer] Pantel. "Breast cancer heterogenity : genetics, estrogen receptor, metastasis, and treatment / Anna Babayan. Betreuer: Klaus Pantel." Hamburg : Staats- und Universitätsbibliothek Hamburg, 2016. http://d-nb.info/1111778140/34.
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Ametti, Merelise Rose. "Parsing Heterogenity In Non-Episodic, Pediatric Irritability: A Transdiagnostic, Research Domain Criteria Informed Approach." ScholarWorks @ UVM, 2019. https://scholarworks.uvm.edu/graddis/1083.
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Background: Approximately 7% of clinically referred youth exhibit profound impairment in the ability to regulate their affect, behavior, and cognition. This phenotype – often referred to as dysregulation – has been associated with a multitude of negative outcomes. Symptom overlap between dysregulation and other psychological disorders has generated debate regarding whether DP constitutes a distinct syndrome characterized by intense, persistent irritability or is merely the combination of symptoms from disruptive or mood disorders. In order to elucidate this question, the current study examined the transdiagnostic continuities and discontinuities in three RDoC constructs (frustrative non-reward, acute threat, and cognitive control) proposed to be mechanisms of irritability
Method: Participants were 294 children ages 7-17 (M=10.94; 67% male). Emotional and behavioral symptoms were measured using the Child Behavior Checklist and the Kiddie Schedule for Affective Disorders and Schizophrenia. Frustrative non-reward was measured using a frustration-induction Go/No-Go paradigm during which heart rate variability was indexed by respiratory sinus arrhythmia (RSA) and pre-ejection period (PEP). Acute threat was measured using an Emotional Faces computer paradigm in conjunction with an eyetracker/pupilometer. Cognitive control was assessed with the Behavioral Rating Inventory of Executive Function (BRIEF), Delis-Kaplan Executive Function System (D-KEFS) and Stop Signal Task (SST).
Results: Symptoms of dysregulation and non-episodic irritability were strongly, positively related. Due to a lack of demonstrated construct validity for the hypothesized RDoC constructs of frustrative non-reward, acute threat, and cognitive control, two alternative mechanisms—SNS response and cognitive dyscontrol of emotion—were derived from the data. Results showed that blunted sympathetic responsivity and poor executive control in response to emotion were predictive of more severe irritability symptoms. Finally, moderation analyses showed that among highly dysregulated children, low levels of sympathetic responsiveness were associated with more severe irritability symptoms.
Conclusions: Despite phenotypic overlap with other forms of developmental psychopathology, dysregulated children can be distinguished based on the severity of their irritability symptoms. This supports the conceptualization of dysregulation as a unique syndrome characterized by intense and persistent irritability and lends credence to the novel diagnosis of DMDD. Furthermore, cognitive, behavioral and physiological patterns identified in this study suggest that difficulties with processing negative emotion—as opposed to frustration or threat specifically—may constitute a vulnerability for irritability.
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Hunter, Emilee Elizabeth. "The Impact of Calendering on the Electronic Conductivity Heterogenity of Lithium-Ion Electrode Films." BYU ScholarsArchive, 2020. https://scholarsarchive.byu.edu/etd/8750.
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Advancements in Li-ion batteries are needed especially for the development of electric vehicles and stationary energy storage. Prior research has shown mesoscale variations in electrode electronic conductive properties, which can cause capacity loss and uneven electrochemical behavior of Li-ion batteries. A micro-four-line probe (μ4LP) was used to measure electronic conductivity and contact resistance over mm-length scales in that prior work. This work describes improvements to overcome the challenge of unreliable surface contact between theμ4LP and the sample. Ultimately a second generation flexible probe called the micro-radial-surface probe (μ4LP) was designed and produced. The test fixture was also optimized to obtain consistent contact with the new measurement probe and to perform measurements at a lower force. The μ4LP was then used to study the effect of heterogeneity on calendering, which is the compression of electrode films to obtain a uniform thickness and desired porosity. The thickness, electronic conductivity and contact resistance of two cathodes and one anode were measured before and after calendering. The the spatial standard deviation divided by the mean was used as a measure of heterogeneity. The results show variability in conductive properties increased for two of the three samples after calendering, despite the increased uniformity in thickness of the electrodes. This suggests that additional quality control metrics are needed besides thickness to be able to identify uneven degradation and produce longer lasting batteries.
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Babayan, Anna Verfasser], and Klaus [Akademischer Betreuer] [Pantel. "Breast cancer heterogenity : genetics, estrogen receptor, metastasis, and treatment / Anna Babayan. Betreuer: Klaus Pantel." Hamburg : Staats- und Universitätsbibliothek Hamburg, 2016. http://nbn-resolving.de/urn:nbn:de:gbv:18-79942.
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Foksová, Eva. "Jsou tenisté racionální?" Master's thesis, Vysoká škola ekonomická v Praze, 2011. http://www.nusl.cz/ntk/nusl-114452.
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The aim of this thesis is to verify the hypothesis on real data based on economic theory and these theories to confirm or reject. The first part deals with testing of hypotheses based on the game theory and tests whether tennis players play according to the minimax theory. The Hypotheses analyse the data for strong and weak players, considering their service, and verify which group of players converge in their strategies toward minimax theory assumptions. Specifically, theory components of the hypotheses are tested within this part: i) the probability of winning the game serving from the right side of a court is the same as the probability of winning the game serving from the left side, ii) this hypothesis will hold true rather in case of stronger players serving against weaker players than in case equally strong players playing against each other and iii) Based on the assumption that women do not excel distinctively in serving, the results in the women's matches will be worse in the minimax theory than results from men's matches. Hypotheses derived from the theory of elimination tournaments are tested in the second part of the diploma thesis. The hypotheses are analysed on the tennis data whether players make less effort in uneven tournaments, regardless of their position as favourite or outsider, than the theory presumes. The analysis of the above mentioned hypotheses was performed on the data from the Grand Slam tournaments in the years 2011 and 2012. Hypotheses are tested using both male and female data. The results obtained from analysis of the data confirm the hypotheses.
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Musilová, Iveta. "PROGRESIVNÍ VÝROBNÍ POSTUPY A MODELOVÁNÍ STRUKTUR A VLASTNOSTÍ LITIN S KULIČKOVÝM GRAFITEM." Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2010. http://www.nusl.cz/ntk/nusl-233882.
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The thesis is concerned with relationships between progressive technological processes of spheroidal graphite cast iron’s production and their structural properties. The aim of the work is to explain causal relationship between parameters of the proposed manufacturing technology of the iron type given (involving selected variants of modification and inoculation of melt and the parameters of melt crystallization, solidification and cooling down in a mould), their structure and even chemical heterogeneity of elements in this structure. For close specification of presented relationships three-dimensional model of spheroidal graphite growth was used, which was developed at the Brno University of Technology, Faculty of Mechanical Engineering. Its usability in praxis has been verified on the basisis of the application of this model on experimentally acquired data. The U GRAFIT 20 model of the authors Stránský and Million counting segregation in the frame of eutectic cell has not still been used for prediction of segregation in real condition in greater extent. On the basis of the above mentioned model microsegregation within “on average” of the cell has been discovered during experimental melts. Microsegregation has been described by segregation and heterogeneity indexes. Calculated values of segregation and heterogeneity indexes have been compared with experimentally verified values. On the basis of comparison of calculated and measured values the possibility of further usage of the mentioned model in praxis has been explored.
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Hodges, Cooper Benton. "Heterogenity in Brain Injury: An Investigation of the Efficacy of Qualitative Comparative Analysis in Diffusion Tensor Imaging." BYU ScholarsArchive, 2020. https://scholarsarchive.byu.edu/etd/8664.
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Traumatic brain injury (TBI) and its associated neural and cognitive sequelae are of increasing interest in military populations. Blast-related TBI is becoming more commonplace in military Service Members and Veterans since Operation Iraqi Freedom/Operation Enduring Freedom/Operation New Dawn and their following conflicts. It is currently unclear whether blast-related injuries cause unique neural and cognitive deficits. The present investigation, in Study 1, aims to investigate the differences in blast-related and non-blast related TBI using traditional statistical techniques. In Study 2, this study will demonstrate the use of Qualitative Comparative Analysis (QCA) in diffusion tensor imaging data. QCA is a relatively new technique that examines configurations of variables that lead to a predefined outcome. QCA has the ability to uncover configurations of variables not yet considered in empirical literature, which may contribute new perspectives on the many different variables often associated with brain injury. Study 1 demonstrated no significant differences between uninjured and injured subjects in white matter integrity, and no differences between blast-related and non-blast related mechanisms. Study 2 demonstrated limited support for the use of QCA in diffusion tensor imaging. Evidence for the use of this method in other neuroimaging modalities is reviewed
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Turon, Helene. "Unemployment dynamics : duration dependence, unemployment flows, equilibrium and disequilibrium." Thesis, University of Bristol, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.390798.
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Islam, Zahurul. "Fractals and fuzzy sets for modelling the heterogenity and spatial complexity of urban landscapes using multiscale remote sensing data." Curtin University of Technology, Department of Spatial Sciences, 2004. http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=15414.
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This research presents models for the analysis of textural and contextual information content of multiscale remote sensing to select an appropriate scale for the correct interpretation and mapping of heterogeneous urban land cover types. Spatial complexity measures such as the fractal model and the Moran’s I index of spatial autocorrelation were applied for addressing the issue of scale, while fuzzy set theory was applied for mapping heterogeneous urban land cover types. Three local government areas (e.g. the City of Perth, the City of Melville and the City of Armadale) of the Perth metropolitan area were selected, as the dominant land covers of these areas are representative to the whole metropolitan area, for the analysis of spatial complexity and the mapping of complex land covers. Characterisation of spatial complexity of the study areas computed from SPOT, Landsat-7 ETM+, and Landsat MSS was used for assessing the appropriateness of a scale for urban analysis. Associated with this outcome, the effect of spectral resolution and land cover heterogeneity on spatial complexity, the performance of fractal measurement algorithms and the relationship between the fractal dimension and Moran’s I were identified. A fuzzy supervised approach of the fuzzy c-means algorithm was used to generate fuzzy memberships of the selected bands of a Landsat-7 ETM+ scene based on the highest spectral separability among different urban land covers (e.g. forest, grassland, urban and dense urban) as determined by a transformed divergence analysis. Fuzzy land cover maps resulting from the application of fuzzy operators (e.g. maximum, minimum, algebraic sum, algebraic product and gamma operators) were evaluated against fuzzy memberships derived from the virtual field reference database (VFRDB).The performance of fuzzy operators in generating fuzzy categorical maps along with the effect of land cover heterogeneity on fuzzy accuracy measures and sources of classification error were assessed. The analysis of spatial complexity computed from remote sensing images using a fractal model indicated that the various urban land cover types of the Perth metropolitan area are best represented at a resolution of 20 m (SPOT) as the fractal dimension (D) was found higher, as compared to the 25 m and 50 m resolutions of the Landsat-7 ETM+ and Landsat MSS, respectively, demonstrated the ability of the fractal model in distinguishing variations in the composition of built-up areas in the green and red bands of the satellite data, while forested areas typical of the urban fringe appear better characterised in the NIR band. Moran’s I of spatial autocorrelation was found useful in describing the spatial pattern of urban land cover types. A comparison between the D and Moran’s I of the study areas revealed a negative correlation, indicating that the higher the Moran’s I, the lesser the fractal dimension indicating a lower spatial complexity. Likewise, the results The accuracy of the fuzzy categorical maps associated with multiple spectral bands of a Landsat-7 ETM+ scene using various fuzzy operators reveals that the fuzzy gamma operator (y = 0.90) outperformed the categorical accuracy measures obtained by applying the fuzzy algebraic sum and other fuzzy operators for the City of Perth, while the accuracy measures of y value of 0.95 were found highest for the City of Melville and the City of Armadale.
A comparison of the accuracy measures of the fuzzy land cover maps of the study areas indicated that the overall accuracy of the City of Perth was up to 13% higher than the overall accuracy of the City of Melville and the City of Armadale which was found 69% and 71%, respectively. The lower accuracy measures of the City of Melville and the City of Armadale was attributed to highly mixed land cover classes resulting in mixed pixels in Landsat-7 ETM+ scene. In addition, the spectral similarity among the class forest and grassland, urban and dense urban were identified as sources of classification errors. The analysis of spatial complexity using multiscale and multisource remote sensing data and the application of fuzzy set theory provided a viable methodology for assessing the appropriateness of scale selection for an urban analysis and generating fuzzy urban land cover maps from a multispectral image. It also illustrated the longstanding issue of carrying out the accuracy of the fuzzy land cover map considering the fuzzy memberships of the classified data and the reference data using a fuzzy error matrix.
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Shaqadan, Ashraf. "Decision Analysis Considering Welfare Impacts in Water Resources Using the Benefit Transfer Approach." DigitalCommons@USU, 2008. https://digitalcommons.usu.edu/etd/54.
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Decision making in environmental management is faced with uncertainties associated with related environmental variables and processes. Decision makers are inclined to use resources to acquire better information in one or more uncertain variable(s). Typically, with limited resources available, characterizing the feasibility of such investment is desirable yet complicated. In the context of reducing inherent uncertainty, decision makers need to tackle two difficult questions, first, the optimal selection of variable(s) and second, the optimal level of information collection which produces maximum gain in benefits. We develop a new framework to assess the socioeconomic value of potential decisions of collecting additional information for given variable(s) to reduce inherent uncertainty. The suggested framework employs advanced social welfare concepts to facilitate eliciting the social acceptability of decisions to collect better information. The framework produces estimates of changes in utility levels and willingness to pay for target population using the benefit transfer method. The practicality of the framework is established using the following common problems in the field of water resources: 1) the uncertainty in exposure to health risk due to drinking a groundwater source contaminated with a carcinogen, 2) the uncertainty in non point source pollution loadings due to unknown hydrologic processes variability, and 3) the equity level in allocating mitigation responsibilities among polluters. For the three applications, the social acceptability of potential decisions is expressed in monetary terms which represent an extension on typical cost benefit analysis by including the socioeconomic value of a decision. The specific contribution of this research is a theoretical framework for a detailed preliminary analysis to transform and represent the given problem in useable terms for the social welfare analysis. The practical framework is attractive because it avoids the need to employ prohibitively expensive survey-based contingent valuation methods. Instead, the framework utilizes benefit transfer method, which imposes a theoretical behavioral structure on population characteristics such as age and income and to produce empirical estimates for a new problem setting.
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Perrier, Anthony. "efpR, un gène stabilisateur des fonctions de virulence et du métabolisme de la bactérie phytopathogène Ralstonia solanacearum." Thesis, Toulouse 3, 2018. http://www.theses.fr/2018TOU30352.
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Ralstonia solanacearum est une bactérie phytopathogène responsable du flétrissement bactérien chez plus de 250 espèces de plantes, dont des plantes à intérêt agronomique telles que la pomme de terre, la tomate ou encore l'arachide. Il a été observé à plusieurs reprises l'apparition de souches virulentes sur des hôtes précédemment décrits comme résistants. Afin de comprendre les bases moléculaires de l'adaptation à ses hôtes, une expérience d'évolution in planta a été réalisée dans mon équipe d'accueil. Pour cela, la souche GMI1000 de R. solanacearum a été maintenue dans la tige de plantes (variétés résistantes, sensibles ou tolérantes) pendant plus de 300 générations bactériennes. A la suite de cette expérience, il a été montré que plus de 80% des clones évolués présentaient un gain de fitness in planta par rapport à la souche ancestrale. Parmi 50 clones re- séquencés, 6 mutations indépendantes dans un même gène de fonction inconnue (renommé efpR) ont été observées, suggérant un fort parallélisme évolutif. L'implication de ces mutations dans le gain de fitness de la bactérie a été validée. Les objectifs de ma thèse ont été (1) de caractériser la fonction du gène efpR et (2) de mieux comprendre son implication dans le gain de fitness in planta de la bactérie. Des approches transcriptomiques et d'analyses métaboliques à haut débit (Biolog), couplées à des validations phénotypiques, ont permis de mettre en évidence que le gène efpR est un régulateur global à l'interface entre le métabolisme et la virulence. Nous avons aussi démontré que toutes les mutations apparues dans le gène efpR étaient des mutations 'perte de fonction' et que ces mutations induisaient un phénomène d'hétérogénéité phénotypique observable sur boite de pétri (2 types de colonies - 1 type sauvage et 1 type mutant). Nous avons mis en évidence un second gène RSc3149, homologue d'efpR, impliqué dans ce switch phénotypique. Le double mutant efpR-RSc3149 étant " verrouillé " dans la forme mutante, nous avons pu étudier l'avantage adaptatif pour la bactérie de générer de l'hétérogénéité phénotypique. [...]Ralstonia solanacearum is a bacterial plant pathogen responsible of the bacterial wilt disease on more than 250 plant species including agronomical crops such as potatoes, tomato and peanuts. It has been reported several times in the literature, the emergence of new pathogenic variants successfully able to infect and induce bacterial wilt disease on previously described resistant plants. To understand the molecular basis of R. solanacearum adaptation to its host, an evolution experiment has been performed in my host team. R. solanacearum has been kept during more than 300 bacterial generations into the stem of several plant species (susceptible, tolerant and resistant plants). At the end of the experiment, the in planta fitness of the derived clones has been tested compared to the ancestral WT strain, and more than 80% of the derived clones had a better fitness. Among them, 50 clones were re-sequenced. Interestingly, 6 independent mutations were found in the same gene of unknown function (renamed efpR), this strongly suggesting an evolutionary parallelism. Reverse genetics approaches confirmed that efpR was involved in the in planta fitness gain. The goals of my thesis were (1) to characterize the function of the efpR gene and (2) to better understand its role in the fitness gain of the bacterium. To do so, transcriptomic and metabolic analysis were performed followed by phenotypic validations. We demonstrated that EfpR is a global regulator of R. solanacearum controlling metabolic and virulence functions. We also demonstrated that all the mutations appeared during the evolution experiment were "loss of function" mutations, these mutations also induced a phenotypic heterogeneity phenomenon. Indeed, 2 types of colonies were observable on plates, one type similar to the colonies formed by the WT strain and another type less mucoid. We also highlighted another gene, the RSc3149 gene which is an efpR homolog involved in the phenotypic heterogeneity. Finaly, most of the efpR related phenotypes were strikingly similar of those associated with a well described regulator of the bacterium, the PhcA major regulator. We performed transcriptomic analysis of both regulons coupled with reporter gene fusions analysis to understand if there was a link between these two regulons and if we could position efpR in the regulatory network of R. solanacearum.[...]
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Klimentová, Jiřina. "Optimalizace procesu tepelného zpracování LKG legovaných niklem." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2010. http://www.nusl.cz/ntk/nusl-229066.
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This work is focused on segregation processes in the matrix of spheroidal graphite cast iron with different silicon and nickel content during heat treatment. The aim of this work is to trace the redistribution of the elements of interest during homogenization annealing with different dwell time by comparison of the effective distribution coefficients. Comparison of some specific properties and description of structure development of spheroidal graphite cast iron matrix from initial state to the state after ferritization and homogenization annealing is included in this work.
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Pavloušková, Zina. "Využití homogenizačního žíhání k potlačení segregace křemíku a niklu v LKG." Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2010. http://www.nusl.cz/ntk/nusl-233926.
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This doctoral thesis deals with the comparison of different methods of alloying elements’ concentration measurement based on energy dispersive spectroscopy and also with the suitability of particular methods of quantitative assessment of heterogeneity of the spheroidal graphite cast iron matrix. The segregation curves construction, distribution coefficient and heterogeneity index formulation is also discussed. The notion “normalized distribution coefficient” is introduced newly. The goal of the thesis, which is to be achieved by means of evaluation of large experimental data sets, is the evaluation of applicability of homogenization annealing of spheroidal graphite cast iron with the aim to eliminate segregation of silicon, and mainly nickel, as pearlite- and carbide-forming agent at the border of an eutectic cell. The result is an optimized homogenization annealing schedule maximizing the suppression of silicon and nickel segregation while taking into account the minimization of financial expenses and risk of grain coarsening.
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Friedrich, Katja, and Nicole Mölders. "A numerical case study on the sensitivity of the water and energy fluxes to the heterogeneity of the distribution of land use." Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-213368.
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Numerical experiments assuming land-use distributions of different heterogeneity of wet and dry surfaces were performed on a cloudy day in spring with a calm wind to examine their influences on the domain-averaged fluxes as well as on the distribution of the fluxes within the domain. The results substantiate that, for ]arge heterogeneity, i.e., small patches, the distribution of the patches plays no role in the magnitude of the atmospheric fluxes. For !arger patches, however, the domain-averaged latent heat-fluxes depend appreciably on both the heterogeneity as well as on the fractional coverage by the land-use types. On the average, for heterogeneous conditions, the prevailing land-use type governs the fluxes. Nevertheless, no exact linearity between the fractionally coverage of the two land-use types and the resulting fluxes exists. Discontinuities in the fluxes which lead to the non-linear behaviour of the domain-averaged fluxes occur at the border between two !arger areas of extremely different characteristics, namely, grass (wet, cool) and sand (dry, warm). Three different patterns of behaviour are found for the temporal development of the differences in the domain-averaged fluxes which depend on both the heterogeneity and the pattern of the land useNumerische Experimente, bei denen unterschiedlich heterogene Landnutzungsverteilungen trockener und feuchte Flächen angenommen werden, wurden für einen wolkigen Schwachwindtag im Frühjahr durchgeführt. Die Ergebnisse belegen, daß bei großer Heterogenität, d.h. kleinen Flächen, deren Anordnung keine Rolle spielt. Bei großen Flächen jedoch hängen die Gebietsmittelwerte der latenten Wärmeflüsse merklich sowohl von der Heterogenität als auch von dem Flächenanteil der Landnutzung ab. Im Mittel beherrscht der vorherrschende Landnutzungstyp die Flüsse. Dennoch ist kein exaktes lineares Verhalten zwischen dem Flächenanteil der Landnutzung und den resultierenden Flüssen vorhanden. Diskontinuitäten in der Verteilung der Flüsse, die letztendlich zu der Nichtlinearität der Gebietsmittelwerte der Flüsse führen, treten an den Grenzen der größeren Flächen unterschiedlicher Oberflächencharakteristika auf, in dieser Studie Gras (feucht, kühl) und Sand (trocken, warm). Drei unterschiedliche Verhaltensweisen im zeitlichen Verlauf der Differenzen der Gebietsmittelwerte der Flüsse wurden gefunden, die vom Muster und der Heterogenität der Landnutzung abhängen
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Bera, Agata Natalia. "Développement d'outils pour suivre la différenciation précoce de cellules souches embryonnaires." Thesis, Strasbourg, 2012. http://www.theses.fr/2012STRAJ042.
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Les cellules souches embryonnaires (ES) sont des cellules pluripotentes, capables de s'auto-renouveller indéfiniment dans des conditions de culture appropriées. Cela signifie que ces cellules restent dans un état prolifératif et indifferencié en culture et ont le potentiel de se différencier dans les trois feuillets embryonnaires, à savoir l'ectoderme, le mésoderme et l’endoderme, et leurs dérivés. Cette capacité à se différencier dans tous les types cellulaires, souligne la diffculté à contrôler la différenciation des cellules ES in vitro et à les guider vers un lignage spécifique. Mon projet de thèse porte sur la différenciation des cellules ES murines. Une étape importante du développement embryonnaire est le choix entre l’ectoderme et le mésendoderme. Dans ce but, j'ai développé une lignée ES qui permet de suivre exclusivement l'expression de Brachyury (T) dans le mésendoderme à l'exclusion de la notochorde: la lignée TRepV. Pour cela, jai cloné un fragment de 1 kb du promoteur murin de Brachyuryen amont du rapporteur Venus (YFP). Avant d'utiliser cette lignée, j’ai cherché à la valider. Malheureusement l'expression du rapporteur TRepV ne reproduit pas fidèlement l'expression endogène de T. Une hypothèse est que le fragment de 1kb ne contient pas tous les éléments de régulation de T nécessaires pour expression fidèle in vitro. De manière surprenante, j’ai observé que le rapporteur TRepV est exprimé de façon hétérogène dans les cellules ES non différenciées. Au cours de mon travail de thèse, je me suis intéressée à cette expression hétérogène. J'ai montré que les cellules ES TRepV+ représentent une sous-population distincte des cellules souches, qui peut être maintenue séparément exprimant le rapporteur de manère stable, à la difference d'autres gènes exprimés de manière hétérogène dans les cellules ES. Nous avons trouvé un marqueur d'une population distincte parmi les cellules ES et de nouveaux gènes impliqués dans pluripotence, qui seront abordés dans des études futuresEmbryonic stem cells (ESCs) are a powerful system to investigate developmental processes in vitro, and a promising tool to generate specific cell types for cellular therapies and regenerative medicine. ESCs are self-renewing, pluripotent cells, maintaining a proliferative and undifferentiated state in culture, while retaining the capacity to differentiate into the three embryonic lineages: ectoderm, mesoderm and endoderm, and all their derivatives. Here, I established a primitive streak specific Brachyury/T Reporter ESC line (TRepV) to investigate early ESC differentiation. In contrast to previously published Tknock-in line, we established a transgene T ESCs reporter line, in order to avoid the disruption of the T locus, which may result in a hapoinsuficient phenotype. During the validation process, I observed discrepancies in expression between the TRepV and the endogenous T locus. I followed upon these observations with a more detailed analysis and obtained evidence that T is regulated differently in the ESC system compared to in vivo development. Against expectations, I also observed heterogeneous expression of the TRepV reporter in undifferentiated ESCs. Undifferentiated ESCs were found to be a mix of TRepV+ and TRepV- cells. This finding became the focus of my studies: I found TRepV+ cells represent a distinct population of ESCs with a unique identity. Unlike other heterogeneous ESC populations (such as Stella or Nanog), TRepV+ cells do not interconvert in their fate and represent an explicit, stable subpopulation of ESCs. Finally, I performed a microarray analysis of TRepV+ and TRepV- ESCs and identifed new genes which may be involved in the regulation of self-renewal and pluripotency
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Bartoň, Vojtěch. "Analýza genetické variability v sekvenačních datech treponemálních kmenů." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2018. http://www.nusl.cz/ntk/nusl-378144.
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This diploma thesis is dealing with methods of identification genetic variability in sequencing data. The resarch is targeted to bacterial strains of Treponema pallidum. The sequencing was performed by Illumina platform. There is a proposition of method to identificate variable spots in resequenced genomes and their analysis and comparation across all processed genomes.
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Rodrigues, Rodicrisller. "Infraestruturas virtuais de computação científica aplicadas na mitigação de heterogeneidade semântica de dados ambientais." Universidade Federal de Mato Grosso, 2015. http://ri.ufmt.br/handle/1/280.
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Com a difusão dos dispositivos eletrônicos e a facilidade na troca de informações qualquer projeto científico usa dados oriundos de diversas fontes. Nesse contexto, dados científicos possuem aspectos semânticos inerentes ao seu processo de aquisição e área de domínio, de forma que para trabalhar com conjuntos de dados de origens diferentes é preciso resolver o problema da heterogeneidade semântica entre eles. Este trabalho enfoca a mitigação da heterogeneidade em dados científicos através do uso de infraestruturas virtuais de Computação Científica. O objetivo principal é demonstrar que soluções em nuvem computacional possuem os requisitos necessários para atender às demandas atuais de um contexto de Computação Científica e e-Science, de forma a facilitar a troca e interação de dados entre contextos heterogêneos
With the diffusion of electronic devices and the facility in exchange of information any scientific project uses data from different sources. In this context, scientific data have semantic aspects inherent to the process of acquisition and domain area, in such a way to work with different sources of data sets is necessary to solve the problem of semantic heterogeneity between them. This work focuses on the mitigation of the heterogeneity on scientific data using virtual infrastructures for Scientific Computing. The main objective is to demonstrate that computational cloud solutions have the necessary requirements to meet the current demands of the context of Scientific Computing and e-Science, in order to facilitate the exchange and interaction of data between heterogeneous environments.
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Hamann, Thomas. "Dynamische Verwaltung heterogener Kontextquellen in global verteilten Systemen." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2009. http://nbn-resolving.de/urn:nbn:de:bsz:14-ds-1233311862785-09186.
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Im Rahmen der Dissertation wurde ein Middlewaredienst entwickelt und realisiert. Es gestattet die dynamische Verwaltung heterogener Kontextquellen. Das zugrunde liegende Komponentenmodell selbstbeschreibender Context Provieder ermöglicht die lose Kopplung von Kontextquellen und -senken. Es wird durch Filter- und Konverterkomponenten zur generischen Providersselektion anhand domänenspezifischer Merkmale ergänzt. Die Kopplung der verteilten Dienstinstanzen erfolgt durch ein hybrides Peer-to-Peer-System. Dies trägt der Heterogenität der Endgeräte Rechnung, und erlaubt die skalierbare , verteilte Verwaltung von Kontextquellen in globalen Szenarien.
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Naumann, Siglinde. "Heterogenität und Bildungsprozesse in bürgerschaftlichen Initiativen : eine empirische Studie zur Transformation konjunktiver Orientierungen." Phd thesis, Universität Potsdam, 2008. http://opus.kobv.de/ubp/volltexte/2008/1978/.
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In dieser qualitativ rekonstruktiven Studie wird an Hand der empirischen Rekonstruktion von Gruppendiskussionen der Fragestellung nachgegangen, welchen handlungsleitenden Orientierungen die Mitglieder der untersuchten Initiativen im Umgang mit ihrer Heterogenität folgen und wie diese Orientierungen mit Lern- beziehungsweise Bildungsprozessen korrespondieren.
Diese Fragestellung ist mit unterschiedlichen theoretischen Kontexten verwoben. Zum Einen geht es hier um Heterogenität und Pluralität. Der Umgang mit Heterogenität und Pluralität gilt als eine zentrale Herausforderung in modernen stark ausdifferenzierten und hochkomplexen Gesellschaften, die mit fluiden mikro- und makrogesellschaftlichen Strukturen (vgl. Schäffter 1998) und vielfältigsten Formen kultureller Pluralität (vgl. Nohl 2006) einhergehen. Ein Reflexionsangebot für die erziehungswissenschaftliche Diskussion bietet die Denkfigur der egalitären Differenz. (Vgl. Prengel Ein Reflexionsangebot für die erziehungswissenschaftliche Diskussion bietet die Denkfigur der egalitären Differenz. Zum Anderen ist eine rekonstruktive Untersuchung bürgerschaftlicher Initiativen nicht ohne Bezug zu ihrem zivilgesellschaftlichen Kontext zu denken. So sei hier stellvertretend für andere zeitdiagnostische Überlegungen auf Giddens Position (vgl. Giddens 1996) verwiesen, der die gesellschaftlichen Veränderungen in der reflexiven Moderne mit weitreichenden Prozessen des sozialen Wandels verbunden sieht. In dieser Studie wird im Anschluss an die strukturale Bildungstheorie von Marotzki (vgl. Marotzki 1990) zwischen Lern- und Bildungsprozessen unterschieden. Vor dem Hintergrund der Theorie Mannheims zu konjunktiven existentiellen Erfahrungen und der damit einhergehenden Seinsverbundenheit des Wissens (vgl. Mannheim 1980) werden diese Prozesse im Anschluss an Schäffers qualitative Studie zu generationenfundierten Bildungsprozessen (vgl. Schäffer 2003) als kollektiv fundierte Prozesse verstanden. Das von Karl Mannheim entwickelte Konzept des „konjunktiven Erfahrungsraums“ (vgl. Mannheim 1980) wird im Anschluss an andere Studien der qualitativen Bildungsforschung (vgl. Schäffer 2003, Nohl 2006) für die Rekonstruktion von Bildungsprozessen genutzt, die auf der Transformation konjunktiver Erfahrungen beruhen.
In der vorliegenden Studie werden die in den untersuchten Initiativen relevanten habituellen Muster des Umgangs mit Heterogenität rekonstruiert und ihre Bedeutung für Lern- und Bildungsprozesse zu erhellt. Bürgerschaftliche Initiativen werden als lebensweltliche Lernorte in den Blick genommen, mit der Auswertung nach der dokumentarischen Methode wird ein Verständnis zu Grunde gelegt, dass auf die Verwobenheit gesellschaftlicher Strukturen mit dem Erleben der Akteure und damit den Prozessen der sozialen Genese von Interaktion und Identität verweist. (Vgl. Bohnsack 2003, Kubisch 2008)This qualitatively rekonstruktive study develops in hand of the empiric reconstruction of group discussions the question which action-leading orientations the members of the examined initiatives follow in dealing with her heterogeneity and how these orientations are connected with learning processes or educational processes.
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Hamann, Thomas. "Dynamische Verwaltung heterogener Kontextquellen in global verteilten Systemen." Doctoral thesis, Technische Universität Dresden, 2008. https://tud.qucosa.de/id/qucosa%3A23737.
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Im Rahmen der Dissertation wurde ein Middlewaredienst entwickelt und realisiert. Es gestattet die dynamische Verwaltung heterogener Kontextquellen. Das zugrunde liegende Komponentenmodell selbstbeschreibender Context Provieder ermöglicht die lose Kopplung von Kontextquellen und -senken. Es wird durch Filter- und Konverterkomponenten zur generischen Providersselektion anhand domänenspezifischer Merkmale ergänzt. Die Kopplung der verteilten Dienstinstanzen erfolgt durch ein hybrides Peer-to-Peer-System. Dies trägt der Heterogenität der Endgeräte Rechnung, und erlaubt die skalierbare , verteilte Verwaltung von Kontextquellen in globalen Szenarien.
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Heitzmann, Daniela, and Uta Klein. "Diversity." Universitätsbibliothek Leipzig, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-220226.
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Unter Diversity (dt.: Vielfalt) wird die Heterogenität und Diversifizierung sozialer Lebenslagen und sozialer Zugehörigkeiten verstanden, die in Folge von unter anderem Migrationsbewegungen, veränderten Geschlechterbeziehungen und der Pluralisierung von Familienformen in westlichen Gesellschaften zunehmen bzw. stärker thematisiert werden als zuvor. Dabei ist eine Lesart vorherrschend, die Diversity als gesellschaftliche und besonders als ökonomische Ressource, als Potenzial, betrachtet.
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Allard, Marc-Antoine. "Hétérogénéité tumorale spatiale et temporelle : description et conséquences thérapeutiques dans les cancers colo-rectaux." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS107.
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L’hétérogénéité tumorale (HT) est un trait caractéristique du cancer. Elle peut être rencontrée chez la majorité des tumeurs malignes solides, au travers de la clinique, la biologie, l’histologie, et la génétique. Au-delà de l’hétérogénéité inter-patient, on distingue l’hétérogénéité spatiale, qui regroupe l’hétérogénéité au sein de la tumeur primitive, entre tumeur primitive et métastases, entre métastases, au sein d’une métastase et l’hétérogénéité temporelle, qui fait référence à l’évolution de la tumeur au cours du temps de manière spontanée ou sous l’effet des traitements. L’HT explique la survenue inéluctable de la résistance aux thérapies anticancéreuses actuelles. L’objectif général de cette thèse était d’explorer l’hétérogénéité tumorale au plan clinique, histologique et génétique en utilisant le modèle d’hépatectomies pour métastases d’origine colo-rectales. Dans l’article 1, nous avons étudié la réponse histologique à la chimiothérapie chez des patients opérés de métastases hépatiques colo-rectales après chimiothérapie systémique ou intra-artérielle. Ainsi, nous avons montré que la réponse histologique complète était plus souvent observée après administration d’oxaliplatine par voie intra-artérielle et était associée à un meilleur pronostic. Cependant la réponse histologique complète n’est observée que chez une minorité de patients. Nous avons émis l’hypothèse qu’une réponse histologique incomplète représentent un groupe hétérogène de patients, ayant des pronostics différents. Ceci nous a conduit à proposer dans l’article 2 une méthode reproductible pour évaluer la réponse histologique, incorporant taille et nombre de nodules. La relecture des lames de pièces d’hépatectomie nous a conduit à observer une hétérogénéité de la réponse histologique au sein d’un même patient (hétérogénéité intermétastatique) et de l’aspect histologique (nécrose, fibrose). Nous avons ensuite exploré la valeur pronostique de cette hétérogénéité et chercher à identifier les facteurs prédictifs de cette hétérogénéité. Une réponse dissociée (une différence de réponse histologique > 50% entre deux nodules chez un même patient) a été observée chez 20% des patients et ne modifiait pas le pronostic. Chez les patients ayant une hétérogénéité pathologique, une discordance (mutation et absence de mutation pour les gènes KRAS, BRAF, NRAS et PI3K) entre les métastases a été mis en évidence dans 28% des patients analysés (article 3). Afin d’étudier l’hétérogénéité génétique selon le site tumoral et le type de prélèvements, nous avons utilisé les données disponibles de la plateforme de biologie moléculaire (article 4). Nous avons ainsi mis en évidence que les métastases hépatiques étaient moins souvent mutées pour KRAS, NRAS, BRAF que les tumeurs primitives ou les lésions pulmonaires. Nous avons ensuite recherché une hétérogénéité génétique intra-métastatique pour KRAS, NRAS, BRAF et PI3K au sein d’une métastase hépatique colo-rectale (article 5). Parmi les 54 patients ayant une tumeur unique analysable (2 prélèvements par tumeur), une discordance pour KRAS (N=2) et BRAF (N=1) a été mise en évidence chez 3 patients (5%). L’ensemble de ces travaux confirment que l’HT est observée à travers de nombreux points de vue. L’élaboration de nouvelles stratégies de prise en charge du cancer devra prendre compte cet aspectTumor heterogeneity is a typical feature of cancer. It is observed in the majority of solid malignancies regardless of the point of view: clinical, biological, pathological, and genetic. Different levels of heterogeneity have been described: interpatient, spatial heterogeneity (within the primary tumor, between primary and distant lesion) and temporal heterogeneity (tumor evolution under the influence of treatment). Tumor heterogeneity widely explains the emergence of resistant clones to anticancer drugs. The objective of the current thesis was to explore tumor heterogeneity at a clinical, pathological and genetic level, by using the model of hepatectomy for colorectal liver metastases (CLM).In the article 1, we studied pathological response to chemotherapy in patients operated on for CLM after either systemic or intra-arterial hepatic oxaliplatin-based chemotherapy. We showed that complete pathological response was more often observed after intra-arterial chemotherapy and yield far better outcomes. However, complete response was observed in a minority of patients. We hypothesized that uncomplete pathological response encompass a large group of patients with different oncological outcomes. This lead us to propose a reproducible method (article 2) to assess pathological response, including size and number of nodules. Pathological review found heterogeneity in the response among nodules within the same patients and in the type of pathological features (necrosis, fibrosis). We then explore the prognostic value of pathological heterogeneity and sought to identify predictors of heterogeneity. A dissociated response (difference in pathological response > 50% between two nodules) was observed in XX and did not impact long-term outcomes. IN patients with dissociated response, genetic heterogeneity (mutation and no mutation for KRAS, NRAS, BRAF and PI3K) between metastases was shown in 28% of patients (article 3). To study genetic heterogeneity according to tumor location and the tumor tissue analyzed (specimen, biopsy), we used data from the department of molecular biology (article 4). We found that liver metastases were more often wild type for KRAS, NRAS, BRAF compared to lung metastases or primary tumors. In the article 5, we then sought to evaluate intrametastatic heterogeneity (KRAS, BRAF, NRAS, PI3K) within a single liver metastasis (2 samples per tumor). Among the 54 patients with single lesion analyzed, a discrepancy for KRAS (n=2) and BRAF (n=1) were observed un 3 patients (5%). This work confirms that tumor heterogeneity can be observed at various levels. Elaboration of new therapeutical strategies will have to take this aspect into consideration
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Lamberti, Giuseppe. "Modelling with heterogeneity." Doctoral thesis, Universitat Politècnica de Catalunya, 2015. http://hdl.handle.net/10803/309295.
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When collecting survey data for a specific study it is usual to have some background information, in the form for example, of socio-demographic variables. In our context, these variables may be useful in identifying potential sources of heterogeneity. Resolving the heterogeneity may mean to perform distinct analyses based on the main variables for distinct and homogeneous segments of the data, defined in terms of the segmentation variables. In 2009 Gastón Sánchez proposed an algorithm PATHMOX with the aim to automatic detecting heterogeneous segments within the PLS-PM methodology. This technique, based on recursive partitioning, produces a segmentation tree with a distinct path models in each node. At each node PATHMOX searches among all splits based on the segmentation variables and chooses the one resulting in the maximal difference between the PLS-PM models in the children nodes. Starting from the work of Sanchez the purpose of the thesis is to extend PATHMOX in the following points:
1. Extension to the PATHMOX approach to detect which constructs differentiate segments. The PATHMOX approach uses a F-global test to identify the best split in heterogeneous segments. Following the same approach it is possible to extend the testing to find which the endogenous constructs are and which are the relationships between constructs responsible of the difference between the segments.
2. Extension to the PATHMOX approach to deal with the factor invariance problem. Originally PATHMOX adapted the estimation of constructs to each detected segment, that is, once a split is performed the PLS-PM model is recalculated in every child. This leads to the problem of invariance: if the the estimation of the latent variables are recalculated in each terminal node of the tree, we cannot be sure to compare the distinct behavior of two individuals who belong to two different terminal nodes. To solve this problem we will propose a invariance test based on the X^2 distribution, where the goal of to test whether the measurement models of each terminal node can be considered equal or not among them.
3. Extension to the PATHMOX approach to overcome the parametric hypothesis of F-test. One critic to the PATHMOX approach, applied in the context of partial least square path modeling, is that it utilizes a parametric test based on the hypothesis that the residuals have a normal distribution to compare two structural models. PLS-PM in general, is utilized to model data that come from survey analysis. These data are characterized by an asymmetric distribution. This situation produces skewness in the distribution of data. As we know, PLS-PM methodology, is based in the absence of assumptions about the distribution of data. Hence, the parametric F test used in PATHMOX may represent a limit of the methodology. To overcome this limit, we will extend the test in the context of LAD robust regression.
4. Generalization of PATHMOX algorithm to any type of modeling methodology. The PATHMOX algorithm has been proposed to analyze heterogeneity in the context of the partial least square path modeling. However, this algorithm can be applied to many other kind of methodologies according to the appropriate split criterion. To generalize PATHMOX we will consider three distinct scenarios: Regression analysis (OLS, LAD, GLM regression) and Principal Component Analysis.
5. Implement the methodology, using the R software as specific library.Cuando se realiza un estudio científico, el análisis hace énfasis sobre las variables recogidas para responder a las preguntas que se quieren hallar durante el mismo estudio. Sin embargo en muchos análisis se suele recoger más variables, como por ejemplo variables socio demográfico: sexo, status social, edad. Estas variables son conocidas como variables de segmentación, ya que pueden ser útiles en la identificación de posibles fuentes de heterogeneidad. Analizar la heterogeneidad quiere decir realizar distintas análisis para distintos colectivos homogéneos definidos a partir de las variables de segmentación. Muchas veces, si hay algún conocimiento previo, esta heterogeneidad puede ser controlada mediante la definición de segmentos a priori. Sin embargo no siempre se dispone de conocimiento suficiente para definir a priori los grupos. Por otro lado muchas variables de segmentación podrían ser disponibles para analizar la heterogeneidad de acuerdo con un apropiado algoritmo. Un algoritmo desarrollado con este objetivo fue PATHMOX, propuesto por Gastón Sanchez en 2009. Esta técnica, utilizando particiones recursivas, produce un árbol de segmentación con distintos modelos asociados a cada nodo. Para cada nodo, PATHMOX busca entre todas las variables de segmentación aquella que produce una diferencia máxima entre los modelos de los nodos hijos. Tomando como punto de partida el trabajo de Gastón Sanchez esta tesis se propone: 1. Extender PATHMOX para identificar los constructos responsables de la diferencias. PATHMOX nos permite detectar distintos modelos en un data-set sin identificar grupos a priori. Sin embargo, PATHMOX es un criterio global. Pera identificar las distintas ecuaciones y coeficientes responsables de las particiones, introduciremos los test F-block y F-coefficient. 2. Extender PATHMOX para solucionar el problema de la invariancia. En el contexto del PLS-PM (Partial Least Squares Path Modeling), PATHMOX funciona fijando las relaciones causales entre las variables latentes y el objetivo es identificar modelos con coeficientes path lo más posible distintos sin poner ninguna restricción sobre el modelo de medida. Por lo tanto, cada vez que una diferencia significativa es identificada, y dos nodos hijos vienen definidos, las relaciones causales entre las variables latentes son las mismas en ambos modelos "hijos", pero la estimación de cada variable latente se recalcula y no podemos estar seguros de comparar el comportamiento de dos individuos distintos que pertenecen a dos nodos diferentes. Para resolver este problema propondremos un test de invariancia basado en la distribución X^2, donde el objetivo del test es verificar si los modelos de cada nodo terminales se puede considerar igual o no entre ellos. 3. Extender PATHMOX para superar la hipótesis paramétrica del F-test. Una crítica a PATHMOX, aplicadas en el contexto del PLS-PM, es que el algoritmo utiliza una prueba paramétrica, basada en la hipótesis de que los residuos tienen una distribución normal, para comparar dos modelos estructurales. Para superar este límite, extenderemos el test para comparar dos regresiones robustas LAD en el contexto del PLS. 4. La generalización del algoritmo PATHMOX a cualquier tipo de metodología. El algoritmo PATHMOX ha sido propuesto para analizar la heterogeneidad en el contexto PLS-PM. Sin embargo, este algoritmo se puede aplicar a muchos otros tipos de metodologías de acuerdo con un apropiado criterio de partición. Para generalizar PATHMOX consideraremos tres escenarios distintos: modelos de regresión (modelos OLS, LAD, GLM) y el análisis en componentes principales. 5. Implementar la metodología, utilizando el software R como librería específica.
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Cleutjens, Jacobus Peter Marie. "Basement membrane heterogeneity." Maastricht : Maastricht : Rijksuniversiteit Limburg ; University Library, Maastricht University [Host], 1989. http://arno.unimaas.nl/show.cgi?fid=5472.
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Shachat, Jason Matthew 1967. "Heterogeneity and equilibrium." Diss., The University of Arizona, 1997. http://hdl.handle.net/10150/289566.
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The research reported in this dissertation explores the observable effects that individual heterogeneity implies in strategic environments. The first chapter provides a focused experimental test of mixed strategy play in strictly competitive games. The experiment directly tests whether serial correlation results from subjects' inability to generate sequences of actions that appear to be time independent, or instead from the play of non-equilibrium strategies. This is achieved by allowing the subjects to generate actions via a simple randomizing device. It is found that serial correlation is not reduced and that subjects adopt a wide variety of non-equilibrium mixed strategies. This wide variety of mixtures potentially explains the seeming paradox of minimax winning proportions with a high variance of win rates across pairs of players. In the second chapter a theoretical model is developed for simultaneous move games in which the observable outcomes are allocations of monetary payoffs or commodity bundles, not expected utility levels. It is assumed that the players' mappings from the uncertain money amounts or commodity bundle allocations to expected utility levels are heterogeneous and are private information. The third chapter applies this framework to investigate the incentives to form agricultural marketing pools.
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Heslop, Louise. "Satellite cell heterogeneity." Thesis, Imperial College London, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.395478.
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Terzi, Ayse, Kees Koedijk, Charles N. Noussair, and Rachel Pownall. "Reference Point Heterogeneity." FRONTIERS MEDIA SA, 2016. http://hdl.handle.net/10150/621274.
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It is well-established that, when confronted with a decision to be taken under risk, individuals use reference payoff levels as important inputs. The purpose of this paper is to study which reference points characterize decisions in a setting in which there are several plausible reference levels of payoff. We report an experiment, in which we investigate which of four potential reference points: (1) a population average payoff level, (2) the announced expected payoff of peers in a similar decision situation, (3) a historical average level of earnings that others have received in the same task, and (4) an announced anticipated individual payoff level, best describes decisions in a decontextualized risky decision making task. We find heterogeneity among individuals in the reference points they employ. The population average payoff level is the modal reference point, followed by experimenter's stated expectation of a participant's individual earnings, followed in turn by the average earnings of other participants in previous sessions of the same experiment. A sizeable share of individuals show multiple reference points simultaneously. The reference point that best fits the choices of the individual is not affected by a shock to her income.
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Heitzmann, Daniela, and Uta Klein. "Diversity." Christian-Albrechts-Universität zu Kiel, 2015. https://ul.qucosa.de/id/qucosa%3A15385.
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Unter Diversity (dt.: Vielfalt) wird die Heterogenität und Diversifizierung sozialer Lebenslagen und sozialer Zugehörigkeiten verstanden, die in Folge von unter anderem Migrationsbewegungen, veränderten Geschlechterbeziehungen und der Pluralisierung von Familienformen in westlichen Gesellschaften zunehmen bzw. stärker thematisiert werden als zuvor. Dabei ist eine Lesart vorherrschend, die Diversity als gesellschaftliche und besonders als ökonomische Ressource, als Potenzial, betrachtet.
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Gräff, Thomas. "Soil moisture dynamics and soil moisture controlled runoff processes at different spatial scales : from observation to modelling." Phd thesis, Universität Potsdam, 2011. http://opus.kobv.de/ubp/volltexte/2011/5447/.
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Soil moisture is a key state variable that controls runoff formation, infiltration and partitioning of radiation into latent and sensible heat. However, the experimental characterisation of near surface soil moisture patterns and their controls on runoff formation remains a challenge. This subject was one aspect of the BMBF-funded OPAQUE project (operational discharge and flooding predictions in head catchments). As part of that project the focus of this dissertation is on: (1) testing the methodology and feasibility of the Spatial TDR technology in producing soil moisture profiles along TDR probes, including an inversion technique of the recorded signal in heterogeneous field soils, (2) the analysis of spatial variability and temporal dynamics of soil moisture at the field scale including field experiments and hydrological modelling, (3) the application of models of different complexity for understanding soil moisture dynamics and its importance for runoff generation as well as for improving the prediction of runoff volumes.
To fulfil objective 1, several laboratory experiments were conducted to understand the influence of probe rod geometry and heterogeneities in the sampling volume under different wetness conditions. This includes a detailed analysis on how these error sources affect retrieval of soil moisture profiles in soils.
Concerning objective 2 a sampling strategy of two TDR clusters installed in the head water of the Wilde Weißeritz catchment (Eastern Ore Mountains, Germany) was used to investigate how well “the catchment state” can be characterised by means of distributed soil moisture data observed at the field scale. A grassland site and a forested site both located on gentle slopes were instrumented with two Spatial TDR clusters that consist of up to 39 TDR probes.
Process understanding was gained by modelling the interaction of evapotranspiration and soil moisture with the hydrological process model CATFLOW. A field scale irrigation experiment was carried out to investigate near subsurface processes at the hillslope scale. The interactions of soil moisture and runoff formation were analysed using discharge data from three nested catchments: the Becherbach with a size of 2 km², the Rehefeld catchment (17 km²) and the superordinate Ammelsdorf catchment (49 km²).
Statistical analyses including observations of pre-event runoff, soil moisture and different rainfall characteristics were employed to predict stream flow volume. On the different scales a strong correlation between the average soil moisture and the runoff coefficients of rainfall-runoff events could be found, which almost explains equivalent variability as the pre-event runoff. Furthermore, there was a strong correlation between surface soil moisture and subsurface wetness with a hysteretic behaviour between runoff soil moisture.
To fulfil objective 3 these findings were used in a generalised linear model (GLM) analysis which combines state variables describing the catchments antecedent wetness and variables describing the meteorological forcing in order to predict event runoff coefficients. GLM results were compared to simulations with the catchment model WaSiM ETH. Hereby were the model results of the GLMs always better than the simulations with WaSiM ETH. The GLM analysis indicated that the proposed sampling strategy of clustering TDR probes in typical functional units is a promising technique to explore soil moisture controls on runoff generation and can be an important link between the scales. Long term monitoring of such sites could yield valuable information for flood warning and forecasting by identifying critical soil moisture conditions for the former and providing a better representation of the initial moisture conditions for the latter.Abflussentwicklung, Infiltration und die Umverteilung von Strahlung in latenten und sensiblen Wärmestrom werden maßgeblich durch die Bodenfeuchte der vadosen Zone gesteuert. Trotz allem, gibt s wenig Arbeiten die sich mit der experimentellen Charakterisierung der Bodenfeuchteverteilung und ihre Auswirkung auf die Abflussbildung beschäftigen. Der Fokus dieser Dissertation wurde darauf ausgerichtet: (1) die Methode des Spatial TDR und deren Anwendbarkeit einschließlich der Inversion des TDR Signals in heterogenen Böden zu prüfen, (2) die Analyse der räumlichen und zeitlichen Dynamik der Bodenfeuchte auf der Feldskala einschließlich Feldexperimenten und hydrologischer Modellierung, (3) der Aufbau verschiedener Modellanwendungen unterschiedlicher Komplexität um die Bodenfeuchtedynamiken und die Abflussentwicklung zu verstehen und die Vorhersage des Abflussvolumens zu verbessern. Um die Zielsetzung 1 zu erreichen, wurden verschiedene Laborversuche durchgeführt. Hierbei wurde der Einfluss der Sondenstabgeometrie und verschiedener Heterogenitäten im Messvolumen bei verschiedenen Feuchtegehalten untersucht. Dies beinhaltete eine detaillierte Analyse wie diese Fehlerquellen die Inversion des Bodenfeuchteprofils beeinflussen. Betreffend der Zielsetzung 2, wurden 2 TDR-Cluster in den Quellgebieten der Wilden Weißeritz installiert (Osterzgebirge) und untersucht, wie gut der Gebietszustand mit räumlich hochaufgelösten Bodenfeuchtedaten der Feldskala charakterisiert werden kann. Um die Interaktion zwischen Evapotranspiration und Bodenfeuchte zu untersuchen wurde das hydrologische Prozessmodell CATFLOW angewendet. Ein Beregnungsversuch wurde durchgeführt um die Zwischenabflussprozesse auf der Hangskala zu verstehen. Die Interaktion zwischen Bodenfeuchte und Abflussentwicklung wurde anhand von drei einander zugeordneten Einzugsgebieten analysiert. Statistische Analysen unter Berücksichtigung von Basisabfluss, Bodenvorfeuchte und verschiedenen Niederschlagscharakteristika wurden verwendet, um auf das Abflussvolumen zu schließen. Auf den verschiedenen Skalen konnte eine hohe Korrelation zwischen der mittleren Bodenfeuchte und dem Abflussbeiwert der Einzelereignisse festgestellt werden. Hierbei konnte die Bodenfeuchte genauso viel Variabilität erklären wie der Basisabfluss. Im Hinblick auf Zielsetzung 3 wurden “Generalised liner models” (GLM) genutzt. Dabei wurden Prädiktorvariablen die den Gebietszustand beschreiben und solche die die Meteorologische Randbedingungen beschreiben genutzt um den Abflussbeiwert zu schätzen. Die Ergebnisse der GLMs wurden mit Simulationsergebnissen des hydrologischen Gebietsmodells WaSiM ETH verglichen. Hierbei haben die GLMs eindeutig bessere Ergebnisse geliefert gegenüber den WaSiM Simulationen. Die GLM Analysen haben aufgezeigt, dass die verwendete Messstrategie mehrerer TDR-Cluster in typischen funktionalen Einheiten eine viel versprechende Methode ist, um den Einfluss der Bodenfeuchte auf die Abflussentwicklung zu verstehen und ein Bindeglied zwischen den Skalen darstellen zu können. Langzeitbeobachtungen solcher Standorte sind in der Lage wichtige Zusatzinformationen bei der Hochwasserwarnung und -vorhersage zu liefern durch die Identifizierung kritischer Gebietszustände für erstere und eine bessere Repräsentation der Vorfeuchte für letztere.
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Patra, Pintu. "Population dynamics of bacterial persistence." Phd thesis, Universität Potsdam, 2013. http://opus.kobv.de/ubp/volltexte/2014/6925/.
Full textAbstract:
The life of microorganisms is characterized by two main tasks, rapid growth under conditions permitting growth and survival under stressful conditions. The environments, in which microorganisms dwell, vary in space and time. The microorganisms innovate diverse strategies to readily adapt to the regularly fluctuating environments. Phenotypic heterogeneity is one such strategy, where an isogenic population splits into subpopulations that respond differently under identical environments. Bacterial persistence is a prime example of such phenotypic heterogeneity, whereby a population survives under an antibiotic attack, by keeping a fraction of population in a drug tolerant state, the persister state. Specifically, persister cells grow more slowly than normal cells under growth conditions, but survive longer under stress conditions such as the antibiotic administrations.
Bacterial persistence is identified experimentally by examining the population survival upon an antibiotic treatment and the population resuscitation in a growth medium. The underlying population dynamics is explained with a two state model for reversible phenotype switching in a cell within the population. We study this existing model with a new theoretical approach and present analytical expressions for the time scale observed in population growth and resuscitation, that can be easily used to extract underlying model parameters of bacterial persistence. In addition, we recapitulate previously known results on the evolution of such structured population under periodically fluctuating environment using our simple approximation method. Using our analysis, we determine model parameters for Staphylococcus aureus population under several antibiotics and interpret the outcome of cross-drug treatment.
Next, we consider the expansion of a population exhibiting phenotype switching in a spatially structured environment consisting of two growth permitting patches separated by an antibiotic patch. The dynamic interplay of growth, death and migration of cells in different patches leads to distinct regimes in population propagation speed as a function of migration rate. We map out the region in parameter space of phenotype switching and migration rate to observe the condition under which persistence is beneficial.
Furthermore, we present an extended model that allows mutation from the two phenotypic states to a resistant state. We find that the presence of persister cells may enhance the probability of resistant mutation in a population. Using this model, we explain the experimental results showing the emergence of antibiotic resistance in a Staphylococcus aureus population upon tobramycin treatment.
In summary, we identify several roles of bacterial persistence, such as help in spatial expansion, development of multidrug tolerance and emergence of antibiotic resistance. Our study provides a theoretical perspective on the dynamics of bacterial persistence in different environmental conditions. These results can be utilized to design further experiments, and to develop novel strategies to eradicate persistent infections.Das Leben von Mikroorganismen kann in zwei charakteristische Phasen unterteilt werde, schnelles Wachstum unter Wachstumsbedingungen und Überleben unter schwierigen Bedingungen. Die Bedingungen, in denen sich die Mikroorganismen aufhalten, verändern sich in Raum und Zeit. Um sich schnell an die ständig wechselnden Bedingungen anzupassen entwickeln die Mikroorganismen diverse Strategien. Phänotypische Heterogenität ist eine solche Strategie, bei der sich eine isogene Popolation in Untergruppen aufteilt, die unter identischen Bedingungen verschieden reagieren. Bakterielle Persistenz ist ein Paradebeispiel einer solchen phänotypischen Heterogenität. Hierbei überlebt eine Popolation die Behandlung mit einem Antibiotikum, indem sie einen Teil der Bevölkerung in einem, dem Antibiotikum gegenüber tolerant Zustand lässt, der sogenannte "persister Zustand". Persister-Zellen wachsen unter Wachstumsbedingungen langsamer als normale Zellen, jedoch überleben sie länger in Stress-Bedingungen, wie bei Antibiotikaapplikation. Bakterielle Persistenz wird experimentell erkannt indem man überprüft ob die Population eine Behandlung mit Antibiotika überlebt und sich in einem Wachstumsmedium reaktiviert. Die zugrunde liegende Popolationsdynamik kann mit einem Zwei-Zustands-Modell für reversibles Wechseln des Phänotyps einer Zelle in der Bevölkerung erklärt werden. Wir untersuchen das bestehende Modell mit einem neuen theoretischen Ansatz und präsentieren analytische Ausdrücke für die Zeitskalen die für das Bevölkerungswachstums und die Reaktivierung beobachtet werden. Diese können dann einfach benutzt werden um die Parameter des zugrunde liegenden bakteriellen Persistenz-Modells zu bestimmen. Darüber hinaus rekapitulieren wir bisher bekannten Ergebnisse über die Entwicklung solch strukturierter Bevölkerungen unter periodisch schwankenden Bedingungen mithilfe unseres einfachen Näherungsverfahrens. Mit unserer Analysemethode bestimmen wir Modellparameter für eine Staphylococcus aureus-Popolation unter dem Einfluss mehrerer Antibiotika und interpretieren die Ergebnisse der Behandlung mit zwei Antibiotika in Folge. Als nächstes betrachten wir die Ausbreitung einer Popolation mit Phänotypen-Wechsel in einer räumlich strukturierten Umgebung. Diese besteht aus zwei Bereichen, in denen Wachstum möglich ist und einem Bereich mit Antibiotikum der die beiden trennt. Das dynamische Zusammenspiel von Wachstum, Tod und Migration von Zellen in den verschiedenen Bereichen führt zu unterschiedlichen Regimen der Populationsausbreitungsgeschwindigkeit als Funktion der Migrationsrate. Wir bestimmen die Region im Parameterraum der Phänotyp Schalt-und Migrationsraten, in der die Bedingungen Persistenz begünstigen. Darüber hinaus präsentieren wir ein erweitertes Modell, das Mutation aus den beiden phänotypischen Zuständen zu einem resistenten Zustand erlaubt. Wir stellen fest, dass die Anwesenheit persistenter Zellen die Wahrscheinlichkeit von resistenten Mutationen in einer Population erhöht. Mit diesem Modell, erklären wir die experimentell beobachtete Entstehung von Antibiotika- Resistenz in einer Staphylococcus aureus Popolation infolge einer Tobramycin Behandlung. Wir finden also verschiedene Funktionen bakterieller Persistenz. Sie unterstützt die räumliche Ausbreitung der Bakterien, die Entwicklung von Toleranz gegenüber mehreren Medikamenten und Entwicklung von Resistenz gegenüber Antibiotika. Unsere Beschreibung liefert eine theoretische Betrachtungsweise der Dynamik bakterieller Persistenz bei verschiedenen Bedingungen. Die Resultate könnten als Grundlage neuer Experimente und der Entwicklung neuer Strategien zur Ausmerzung persistenter Infekte dienen.
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Friedrich, Katja, and Nicole Mölders. "A numerical case study on the sensitivity of the water and energy fluxes to the heterogeneity of the distribution of land use." Universität Leipzig, 1998. https://ul.qucosa.de/id/qucosa%3A15078.
Full textAbstract:
Numerical experiments assuming land-use distributions of different heterogeneity of wet and dry surfaces were performed on a cloudy day in spring with a calm wind to examine their influences on the domain-averaged fluxes as well as on the distribution of the fluxes within
the domain. The results substantiate that, for ]arge heterogeneity, i.e., small patches, the distribution of the patches plays no role in the magnitude of the atmospheric fluxes. For !arger patches, however, the domain-averaged latent heat-fluxes depend appreciably on both the heterogeneity as well as on the fractional coverage by the land-use types. On the average, for heterogeneous conditions, the prevailing land-use type governs the fluxes. Nevertheless, no exact linearity between the fractionally coverage of the two land-use types and the resulting fluxes exists. Discontinuities in the fluxes which lead to the non-linear behaviour of the domain-averaged fluxes occur at the border between two !arger areas of extremely different characteristics, namely, grass (wet, cool) and sand (dry, warm). Three different patterns of behaviour are found for the temporal development of the differences in the domain-averaged fluxes which depend on both the heterogeneity and the pattern of the land use.Numerische Experimente, bei denen unterschiedlich heterogene Landnutzungsverteilungen trockener und feuchte Flächen angenommen werden, wurden für einen wolkigen Schwachwindtag im Frühjahr durchgeführt. Die Ergebnisse belegen, daß bei großer Heterogenität, d.h. kleinen Flächen, deren Anordnung keine Rolle spielt. Bei großen Flächen jedoch hängen die Gebietsmittelwerte der latenten Wärmeflüsse merklich sowohl von der Heterogenität als auch von dem Flächenanteil der Landnutzung ab. Im Mittel beherrscht der vorherrschende Landnutzungstyp die Flüsse. Dennoch ist kein exaktes lineares Verhalten zwischen dem Flächenanteil der Landnutzung und den resultierenden Flüssen vorhanden. Diskontinuitäten in der Verteilung der Flüsse, die letztendlich zu der Nichtlinearität der Gebietsmittelwerte der Flüsse führen, treten an den Grenzen der größeren Flächen unterschiedlicher Oberflächencharakteristika auf, in dieser Studie Gras (feucht, kühl) und Sand (trocken, warm). Drei unterschiedliche Verhaltensweisen im zeitlichen Verlauf der Differenzen der Gebietsmittelwerte der Flüsse wurden gefunden, die vom Muster und der Heterogenität der Landnutzung abhängen.
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Economides, George, and Thomas Moutos. "Minimum Wages in the Presence of In-Kind Redistribution." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-226503.
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To many economists the public's support for the minimum wage (MW) institution is puzzling, since the MW is considered a "blunt instrument'' for redistribution. To delve deeper in this issue we build models in which workers are heterogeneous in ability. In the first model, the government does not engage in any type of redistributive policies - except for the payment of unemployment benefits; we find that the MW is preferred by the majority of workers (even when the unemployed receive very generous unemployment benefits). In the second model, the government engages in redistribution through the public provision of private goods. We show that (i) the introduction of a MW can be preferred by a majority of workers only if the unemployed receive benefits which are substantially below the after-tax earnings they would have had in the perfectly competitive case, (ii) for a given generosity of the unemployment benefit scheme, the maximum, politically viable, MW is lower than in the absence of in-kind redistribution, and (iii) the MW institution is politically viable only when there is a limited degree of in-kind redistribution. These findings can possibly explain why a well-developed social safety net in Scandinavia tends to co-exist with the absence of a national MW, whereas in Southern Europe the MW institution "complements'' the absence of a well-developed social safety net.
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Boedeker, Peter. "Comparison of Heterogeneity and Heterogeneity Interval Estimators in Random-Effects Meta-Analysis." Thesis, University of North Texas, 2018. https://digital.library.unt.edu/ark:/67531/metadc1157553/.
Full textAbstract:
Meta-analyses are conducted to synthesize the quantitative results of related studies. The random-effects meta-analysis model is based on the assumption that a distribution of true effects exists in the population. This distribution is often assumed to be normal with a mean and variance. The population variance, also called heterogeneity, can be estimated numerous ways. Accurate estimation of heterogeneity is necessary as a description of the distribution and for determining weights applied in the estimation of the summary effect when using inverse-variance weighting. To evaluate a wide range of estimators, we compared 16 estimators (Bayesian and non-Bayesian) of heterogeneity with regard to bias and mean square error over conditions based on reviews of educational and psychological meta-analyses. Three simulation conditions were varied: (a) sample size per meta-analysis, (b) true heterogeneity, and (c) sample size per effect size within each meta-analysis. Confidence or highest density intervals can be calculated for heterogeneity. The heterogeneity estimators that performed best over the widest range of conditions were paired with heterogeneity interval estimators. Interval estimators were evaluated based on coverage probability, interval width, and coverage of the estimated value. The combination of the Paule Manel estimator and Q-Profile interval method is recommended when synthesizing standardized mean difference effect sizes.
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Yegorov, Yuri. "Spatial Heterogeneity and Equilibrium." Doctoral thesis, Universitat Pompeu Fabra, 1999. http://hdl.handle.net/10803/7592.
Full textAbstract:
This thesis consists of five chapters, based on four different articles. All of them are devoted to different aspects of spatial heterogeneity and its impact on economic equilibrium in space. The concept of heterogeneous continuous space is discussed in the introductory chapter.The first model "Equilibrium in Continuous Space under Decentralized Production" addresses the issue of the impact of differences across locations in exogeneous productivity on the structure of equilibrium prices, production and trade. The goal is to describe the general equilibrium in a spatially decentralized economy, when production, consumption and markets are distributed in continuous space and transportation costs are essentially linear. It is shown that an autarky equilibrium can exist only if transport costs are high enough. In the general case, the general equilibrium in this model includes some endogeneously determined trade areas, with flows of goods across space, and autarky areas where production and consumption activities take place only at the same point. An analytical solution in explicit functions is obtained; it contains equilibrium prices, labor supply and flows of goods as functions of the spatial variable. The model can be applied to a set of practical questions in regional economics. In particular, it is able to describe persistent price differentials across regions and non-local consequences of road construction and transportation cost shocks for the economy. The differences across locations in population density may have either historical or economic reasons.
The second model "Hotelling's Revival" extends a well-known research of H.Hotelling (1929) to the two-dimensional case with spatially heterogeneous demand density, preserving the rest of his classical assumptions. It is shown that the problem of demand discontinuity in the one-dimensional model, which was discovered by d'Aspremont, Gabszewich and Thisse (1979), disappears in this case. This also holds for any bounded distribution of consumers on any compact set on a plane, which can describe real geographical situations. Demand continuity still holds for any transport costs, strictly increasing in distance and not necessarily linear. Although this is sufficient for the existence of Nash equilibrium in mixed strategies, in pure strategies it exists only for some subset of cases. Examples of both existence and non-existence are constructed, and for some family of densities the separation point between the two cases is found.
The third model addresses locational choice of heterogeneous consumers, when land is also heterogeneous in quality. It is based on two articles. The first, "Dacha Pricing", is presented in chapter 4 and studies the problem of locational rent in a city-neighbourhood when utility includes both the impact of transport costs and time for transportation. For the case of identical agents the problem is solved explicitly and comparative statics with respect to exogeneous changes in transport cost and speed is studied. For the case of agents who are heterogeneous with respect to their income, a solution is also obtained. The model explains some evidence about dacha pricing in Russia and its dynamics during the transition period. The second article related to this model is "Location and Land Size Choice by Heterogeneous Agents". It generalizes the first one and form a separate chapter 5. A new approach about the general equilibrium allocation of heterogeneous divisible good (like land) among a continuum of heterogeneous consumers is proposed. The model is based on continuity of primitives which allow not only to finding a general equilibrium solution in a class of continuous functions, but also to treat the solution to a continuous problem as the limit of the corresponding sequence of discrete problems. This solves one of Berliant's paradoxes, related to spatial economics. The multiplicity of equilibria is shown to take place.
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Pinto, Eugenio. "Heterogeneity and input reallocation." College Park, Md. : University of Maryland, 2006. http://hdl.handle.net/1903/3903.
Full textAbstract:
Thesis (Ph. D.) -- University of Maryland, College Park, 2006.Thesis research directed by: Economics. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Jonnalagadda, Deepa. "HETEROGENEITY IN PLATELET EXOCYTOSIS." UKnowledge, 2013. http://uknowledge.uky.edu/biochem_etds/8.
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Platelet exocytosis is essential for hemostasis and for many of its sequelae. Platelets release numerous bioactive molecules stored in their granules enabling them to exert a wide range of effects on the vascular microenvironment. Are these granule cargo released thematically in a context-specific pattern or via a stochastic, kinetically-controlled process? My work describes platelet exocytosis using a systematic examination of platelet secretion kinetics. Platelets were stimulated for increasing times with different agonists (i.e. thrombin, PAR1-agonist, PAR4-agonist, and convulxin) and micro-ELISA arrays were used to quantify the release of 28 distinct α-granule cargo molecules. Agonist potency directly correlated with the speed and extent of release. PAR4-agonist induced slower release of fewer molecules while thrombin rapidly induced the greatest release. Cargo with opposing actions (e.g. pro- and anti-angiogenic) had similar release profiles, suggesting limited thematic response to specific agonists. From the release time-course data, rate constants were calculated and used to probe for underlying patterns. Probability density function and operator variance analyses were consistent with three classes of release events, differing in their rates. The distribution of cargo into these three classes was heterogeneous suggesting that platelet secretion is a stochastic process potentially controlled by several factors such as cargo solubility, granule shape, and/or granule-plasma membrane fusion routes.
Sphingosine 1 phosphate (S1P) is a bioactive lipid that is stored in platelets. S1P is essential for embryonic development, vascular integrity, and inflammation. Platelets are an abundant source of S1P due to the absence of the enzymes that degrade it. Platelets release S1P upon stimulation. My work attempts to determine how this bioactive lipid is released from platelets. Washed platelets were stimulated with agonists for defined periods of time and the supernatant and pellet fractions were separated by centrifugation. Lipids were separated by liquid phase extraction and S1P was quantified with a triple quadrapole mass spectrometer. A carrier molecule (BSA) is required to detect release of S1P. Further, there is a dose-dependent increase in total S1P with increasing BSA. S1P release shows characteristics similar to other platelet granule cargo e.g. platelet factor IV (PF4). Platelets from Unc13-d Jinx mice and VAMP8-/- mice, which are secretion-deficient (dense granule, alpha granule and lysosome), were utilized to understand the process of S1P release. S1P release was more affected in Unc13-d Jinx mice mirroring their dense granule secretion defect. Fluorescence microscopy and sub-cellular fractionation were used to examine localization of S1P in platelets. S1P was observed to be enriched in a granule population. These studies indicate the existence of two pools of S1P, a readily extractable agranular pool, sensitive to BSA, and a granular pool that requires the secretion machinery for release. The secretion machinery of platelets in addition to being involved in the release of normal granule cargo is thus proved to be involved in the release of bioactive lipid molecules like S1P.
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Marks, John. "Michel Foucault : towards heterogeneity." Thesis, Nottingham Trent University, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.357156.
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Mealor, Michael A. "Spatial heterogeneity in ecology." Thesis, University of Stirling, 2005. http://hdl.handle.net/1893/53.
Full textAbstract:
This project predominantly investigated the implications of spatial heterogeneity in the ecological processes of competition and infection. Empirical analysis of spatial heterogeneity was carried out using the lepidopteran species Plodia interpunctella. Using differently viscous food media, it was possible to alter the movement rate of larvae. Soft Foods allow the movement rate of larvae to be high, so that individuals can disperse through the environment and avoid physical encounters with conspecifics. Harder foods lower the movement rate of larvae, restricting the ability of individuals to disperse away from birth sites and avoid conspecifics encounters. Increasing food viscosity and lowering movement rate therefore has the effect of making uniform distributed larval populations more aggregated and patchy. Different spatial structures changed the nature of intraspecific competition, with patchy populations characterised by individuals experiencing lower growth rates and greater mortality because of the reduced food and space available within densely packed aggregations. At the population scale, the increased competition for food individuals experience in aggregations emerges as longer generational cycles and reduced population densities. Aggregating individuals also altered the outcome of interspecific competition between Plodia and Ephestia cautella. In food media that allowed high movement rates, Plodia had a greater survival rate than Ephestia because the larger movement rate of Plodia allowed it to more effectively avoid intraspecific competition. Also the faster growth rate, and so larger size, of Plodia allowed it to dominate interspecific encounters by either predating or interfering with the feeding of Ephestia. In food that restricts movement, the resulting aggregations cause Plodia to experience more intraspecific encounters relative to interspecific, reducing its competitive advantage and levelling the survival of the two species. Spatial structure also affected the dynamics of a Plodia-granulosis virus interaction and the evolution of virus infectivity. Larval aggregation forced transmission to become limited to within host patches, making the overall prevalence of the virus low. However potentially high rates of cannibalism and multiple infections within overcrowded host aggregations caused virus-induced mortality to be high, as indicated by the low host population density when virus is presented. Also aggregated host populations cause the evolution of lower virus infectivity, where less infective virus strains maintain more susceptible hosts within the aggregation and so possess a greater transmission rate. The pattern of variation in resistance of Plodia interpunctella towards its granulosis virus was found using two forms of graphical analysis. There was a bimodal pattern of variation, with most individuals exhibiting either low or high levels of resistance. This pattern was related to a resistance mechanism that is decreasingly costly to host fitness.
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Osypiw, Jacqueline Connett. "Heterogeneity of rat hepatocytes." Thesis, Liverpool John Moores University, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.261422.
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Restivo, Andrea. "Core-mantle boundary heterogeneity." Thesis, University of Bristol, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.271844.
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Coghill, David Rockwell. "Heterogeneity in hyperkinetic disorder." Thesis, University of Dundee, 2010. https://discovery.dundee.ac.uk/en/studentTheses/afa9d9e9-eadb-49bf-8c83-db47eb0cadd9.
Full textAbstract:
It is increasingly recognised that the broadly defined behavioural phenotype of attention deficit – hyperactivity disorder (ADHD) is a heterogeneous condition and that this heterogeneity is seen across all levels of analysis from the genetic and environmental causes to the associated neuropsychological deficits, the clinical presentation and response to treatment. This work investigated whether the more restrictive and clinically homogeneous hyperkinetic disorder (HKD) phenotype is associated with reduced neuropsychological heterogeneity compared with the broader ADHD phenotype. Using a well known, broad based battery of neuropsychological tasks from the Cambridge Neuropsychological Test Automated Battery (CANTAB) and a computerised Go/NoGo task in a large well described group of boys with rigorously diagnosed HKD who were stimulant medication naïve at baseline, it was demonstrated that the neuropsychological heterogeneity in the HKD boys was very similar to that seen previously in children with ADHD. Interestingly, and contrary to popular opinion, the strongest associations were with more simple recognition memory tasks with a low executive demand. Although there were significant associations between HKD and deficits on a range of tasks with high executive demands these were less strong. Could this neuropsychological heterogeneity be a function of different developmental issues or comorbidity? With respect to development there was evidence that boys with HKD lagged behind the healthy boys with respect to the development of their neuropsychological performance. However the pattern of development was similar with the performance of the HKD boys paralleling that of the healthy boys, suggesting that the neuropsychological heterogeneity seen in HKD is not accounted for by developmental issues. With respect to the relationship between neuropsychological functioning and comorbidity, the impact of comorbid oppositional defiant disorder (ODD) and conductdisorder (CD), it was found that all three clinical groups (pure HKD, HKD + ODD and HKD + CD) demonstrated deficits on several tasks compared with the healthy boys. Compared with healthy boys each of the three clinical groups was associated with at least one unique neuropsychological deficit. This suggests that comorbidity between HKD and both ODD and CD may contribute to the neuropsychological heterogeneity in the HKD boys. Is there an association between clinical and neuropsychological responses to the treatment of HKD with the stimulant drug methylphenidate (MPH)? Detailed analyses were conducted to investigate heterogeneity of clinical and neuropsychological response in these boys to MPH. As predicted in previous studies there is evidence for clinical heterogeneity in response with between 68 and 78% of boys with HKD responding to MPH treatment at either one or both of the doses. The precise proportion responding was dependent on the scale and definition of response used. Clinical response was not predicted by age but was predicted to a degree by severity of symptoms at baseline and it was generally true that better response was predicted by lower (better) scores at baseline. Baseline performance on a component reflecting recognition memory performance at baseline predicted clinical response to the lower (0.3 mg/kg/dose), but not the higher (0.6, mg/kg/dose) dose of MPH with poorer baseline neuropsychological performance predicting a better clinical response. Whilst there was improvement on some neuropsychological measures following administration of MPH there was little association between clinical and neuropsychological responses to medication. Clinical response was only associated with neuropsychological response on a single measure from a single task (Go/NoGo Block 2 Errors to Distractors), a task that did not itself discriminate between the HKD boys and healthy Controls at baseline.
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Bretan, Pedro Luis Accioli Nobre. "Firm heterogeneity and lobbying." reponame:Repositório Institucional do FGV, 2006. http://hdl.handle.net/10438/109.
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Previous issue date: 2006-12-18The structure of protection across sectors is usually interpreted as the result of competition among lobbies to influence politicians, but little attention has been devoted to the importance of individual firms in this process. This paper builds a model incorporating firm heterogeneity into a lobbying setup `a la Grossman and Helpman (1994), in a monopolistic competitive environment. We obtain that increased sectorial dispersion cause a fall in equilibrium tariff provided that the exporter’s cutoff is above the mean of the distribution. Also, higher average productivity brings about a fall in the equilibrium tariff, whereas an increase in export costs cause an increase in the tariff. JEL Classification codes: D43, D7, F12, F13, L11
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Gonçalves, Carlos Augusto. "Characterisation of formation heterogeneity." Thesis, University of Leicester, 1995. http://hdl.handle.net/2381/35033.
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The characterisation of formation heterogeneities requires a multidisciplinary study of data acquired using a large number of numerical geophysical and geological measurements and a rigorous evaluation of the precision and accuracy of the data. Another essential aspect of the appraisal of any measurement is the quality assessment and quality control of the data. In this work multivariate statistical techniques and an Artificial Neural Network (ANN) are used provide lithofacies characterisation and to identify heterogeneities in complex formations as well as to evaluate the boundaries they generate. The precision and accuracy of the data from different sources are very important and are considered here by using sample support in the integration of measurements at different scales. We use examples from two holes of the Ocean Drilling Program and two oilfield holes to show the differences in characterisation obtained with each technique. Multivariate Statistical Analysis are initially used to group the petrophysical, geophysical and geological parameters extracted from the downhole measurements into distinct geologically definable zones. This technique has the advantage of being quasi-independent of any pre-determined ideas we have about the whole dataset, and has proved very reliable in formation characterisation. Thus the result obtained here is used as a basis for comparison with that obtained from the Neural Network. Artificial Neural Network is used to characterise the different lithology sequences present in each well. Neural Networks are relatively new tools and have proved very useful in applications where conventional computing methods are inadequate. Another application is the possibility of determining quantitative petrophysical parameters from well logs and core data in uncored intervals. The results are presented as a comparison between the two techniques. We show that both methods are very encouraging. When comparing the ANN derived petrophysical parameter logs with actual core measurements and other petrophysical parameters prediction techniques we see a good match. Low quality petrophysical measurements can be determined by a mismatch between the responses.
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Branford, White Harriet A. "Heterogeneity in Ewing sarcoma." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:7af59b69-e68f-41af-b5f0-8a7d278f6fd7.
Full textAbstract:
Ewing sarcoma, an aggressive primary bone and soft tissue tumour is characterised by the expression of the chimeric transcription factor EWS-FLI1 in 90% of patients. This alters expression of many genes including activation of the Insulin Growth Factor (IGF) pathway via IGFBP3 supression. Phase I/II trials with an IGF-1 inhibitor have demonstrated tumour regression in a modest number of Ewing sarcoma patients. The aim of this thesis was to identify mechanisms contributing to the heterogeneity of resistance in Ewing sarcoma following inhibition with OSI-906, a dual kinase inhibitor of IGF-1 (IGF-1R) and Insulin (IR) receptors. The hypothesis was that mechanisms of resistance relate to heterogeneity of responses to signalling pathway activation and inhibition. Through selection, disruption of the pathway would identify subpopulations of cells both sensitive and resistant in their response allowing for interrogation of resistance mechanisms. A genome wide approach was taken to model the resistance profile of cell lines. Through developing a method of unbiased quantification, a panel of validated Ewing sarcoma cell lines (EuroBoNet) were imaged and segmented to assess the responses of biomarkers on signalling pathway activation. Heterogeneity was confirmed between cell lines. The application to diagnostic biopsies led to the identification of prognostic classifiers and cellular subpopulations with clinical prognostic significance. The distribution of Ki67 was found to be predictive of survival and cells with lower levels of CD99 in the cytoplasm were most discriminative. Parallel sequencing strategies (RNA-seq, whole exome sequencing, and aCGH/ SNP array) for genome-wide screening was carried out for point mutations, copy number changes and rearrangements. Systematic detection was used to characterise genomic rearrangements and functional validation performed. Resistant clones, formed via ENU mutagenesis of cell lines, were sequenced in order to demonstrate the resistance profile of OSI-906. In summary heterogeneity of Ewing sarcoma at the genomic and proteomic level can influence the signalling dependency of tumours and response to inhibitors. Genomic and proteomic profiling of tumour cells may be relevant to future developments of novel therapies.
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Hoermann, Gudrun. "Mortality heterogeneity and life insurance /." [S.l.] : [s.n.], 2009. http://opac.nebis.ch/cgi-bin/showAbstract.pl?sys=000293554.
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Boneng, Yus T. "Weibull frailty for modelling heterogeneity." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/NQ61968.pdf.
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Vamvakidou, Alexandra P. T̈ozeren Aydin. "Phenotypic heterogeneity of breast tumors /." Philadelphia, Pa. : Drexel University, 2007. http://hdl.handle.net/1860/1777.
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Botman, Dennis Petrus Johannes. "Globalization, heterogeneity, and imperfect information." [Amsterdam : Amsterdam : Thela Thesis] ; Universiteit van Amsterdam [Host], 2001. http://dare.uva.nl/document/59482.
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