Les récepteurs pentamériques canaux (pLGICs) sont des récepteurs neuronaux impliqués dans la neurotransmission rapide et qui comprennent les récepteurs suivants : nAchR, GABAR, GlyR or 5HT3R. Lorsqu’ils ne fonctionnent pas correctement ils sont impliqués dans des pathologies comme Alzheimer ou Parkinson. Dans cette étude, nous avons réalisé des simulations de dynamique moléculaire d’un homologue procaryote des pLGICs. Grâce à l’analyse de 2.5 us de simulation nous avons pu capturer la fermeture complète dudit récepteur et décrire un mécanisme de gating. Ce mécanisme en deux étapes, 1) twisting puis 2) blooming semble compatible avec tous les pLGICs. Dans un second temps, nous avons utilisé notre connaissance du mécanisme de gating afin de faire des calculs d’énergie libre le long du twisting, pour différents complexes protéine/ligands. De cette façon, nous avons pu discriminer entre des ligands actifs et inactifs et ainsi fournir des pistes pour le design de nouveaux traitements. / Pentameric ligand gated ion channels (pLGICs) are brain receptors involved in fast neurotransmission and include nAchR, GABAR, GlyR or 5HT3R. When dysfunctioning, they are involved in diseases such as Alzheimer’s and Parkinson’s. In this study we have performed molecular dynamic simulations of an eukaryotic homologue of the pLGICs (GluCl) to understand the gating mechanism of pLGICs. Thanks to the analysis of two 2.5 us long simulations in which we could capture the full closing of the receptor we described in great details a gating mechanism in two steps, first twisting then blooming, that we believe applicable to the whole pLGICs family. In a second time we used our description of the gating mechanism to perform free energy calculations along the twisting reaction coordinate, for various ligands in complex with GluCl. Doing so we could show a significant difference between IVM-bound and non-bound states and provide hints for the design of new treatments.

Economists take an interest in property rights structures because of their importance in the definition of incentive structures. Fisheries have been analyzed as open access resources because they are not often organized around private property rights. The lack of private property rights though should not be taken to imply unlimited access. There is a need to differentiate between situations in which an institutional structure supports a system of common property rights from those in which access to a resources is truly limited. In this study, a conceptual framework of the structure and workings of property rights to natural resources is developed. This includes a taxonomy of possible property rights structures that differentiates among types and degrees of common and private property. The study then compares and contrasts the differing views in the economics literature on the process by which property rights evolve. This conceptual framework is used to develop a set of research questions that will structure the inquiry about the evolution of property rights to a specific natural resource, the Chesapeake Bay oyster grounds. The conventional and Institutionalist perspectives are related to fishery management policy and their differences assessed. The Institutionalist perspective is shown to raise questions about the historical development of property rights that would not be considered by conventional economists. The resulting research questions are used to explain the economic history of the property rights to the Chesapeake Bay oyster grounds from 1607 to 1986. In Maryland and Virginia certain grounds of the Chesapeake Bay are reserved as a public oyster fishery, but, they have been regulated and managed by the states. In the history of the fishery, those who harvest from the public grounds have continually resisted the extension, or even encouragement of oyster cultivation on private leaseholds. The primary advocates of greater privatization of the bottoms have been economists and biologists. The governments of each state have chosen to maintain the commons in order to provide employment for watermen and to more widely distribute income among them. The results of a survey of Virginia's oyster harvesters are presented. These provide further insights for discussing the role of the watermen in the evolution of property rights, and help to form conclusions on the future of the fishery. This case study leads to the discussion of conclusions on the theory of the economics of property rights. / Ph. D.

Texture can be broadly stated as spatial variation of image intensities. Texture analysis and classification is a well researched area for its importance to many computer vision applications. Consequently, much research has focussed on deriving powerful and efficient texture descriptors. Local binary patterns (LBP) and its variants are simple yet powerful texture descriptors. LBP features describe the texture neighbourhood of a pixel using simple comparison operators, and are often calculated based on varying neighbourhood radii to provide multi-resolution texture descriptions. A comprehensive evaluation of different LBP variants on a common benchmark dataset is missing in the literature. This thesis presents the performance for different LBP variants on texture classification and retrieval tasks. The results show that multi-scale local binary pattern variance (LBPV) gives the best performance over eight benchmarked datasets. Furthermore, improvements to the Dominant LBP (D-LBP) by ranking dominant patterns over complete training set and Compound LBP (CM-LBP) by considering 16 bits binary codes are suggested which are shown to outperform their original counterparts. The main contribution of the thesis is the introduction of multi-dimensional LBP features, which preserve the relationships between different scales by building a multi-dimensional histogram. The results on benchmarked classification and retrieval datasets clearly show that the multi-dimensional LBP (MD-LBP) improves the results compared to conventional multi-scale LBP. The same principle is applied to LBPV (MD-LBPV), again leading to improved performance. The proposed variants result in relatively large feature lengths which is addressed using three different feature length reduction techniques. Principle component analysis (PCA) is shown to give the best performance when the feature length is reduced to match that of conventional multi-scale LBP. The proposed multi-dimensional LBP variants are applied for medical image analysis application. The first application is nailfold capillary (NC) image classification. Performance of MD-LBPV on NC images is highest, whereas for second application, HEp-2 cell classification, performance of MD-LBP is highest. It is observed that the proposed texture descriptors gives improved texture classification accuracy.

Class of 2010 Abstract / OBJECTIVES: The purpose of this project was to analyze the accuracy of season two, episodes 13-­‐24 of the popular medical drama, House, MD. METHODS: This study was a descriptive retrospective analysis of the second half of season two of House, MD. The accuracy of the presenting signs and symptoms, diagnosis, and treatment in each episode was rated on a scale of one to four. A rating of one described a correct and usual representation. A rating of two described a correct but somewhat unusual representation. A rating of three described a correct but extremely unusual representation. A rating of four described an incorrect representation. Each researcher independently rated the episodes, and then a collaborative rating was agreed upon by all researchers. RESULTS: Results of the ANOVA test demonstrated a statistically significant difference between the three dependent variables (p=0.003). The Tukey post-­‐hoc test confirmed a significant difference between the accuracy of treatment when compared with signs and symptoms (p=0.003), and with diagnosis (p=0.022). The average rating for the treatment variable was 1.50 (±0.707), whereas the average ratings for the signs and symptoms and diagnosis variables were 2.80 (±0.919) and 2.50 (±0.707), respectively. CONCLUSIONS: The treatments presented in the last twelve episodes of season two of House, MD were more accurate than both the presenting signs and symptoms and the diagnosis.

Class of 2009 Abstract / OBJECTIVES: The purpose of this work was to quantify the magnitude of factual inaccuracies in the first twelve episodes of the second season of the medical drama, House, MD. METHODS: This study was a descriptive retrospective evaluation of the first twelve episodes in the second season of the popular television show, House, MD. The degree of accuracy of the signs and symptoms (presentation), diagnosis, and treatment for the one major disease portrayed in each show was rated on a scale of one to four. Each researcher evaluated these ratings independently, and after subsequent collaborative discussion, a combined rating was determined for all the data. RESULTS: Both a three-way ANOVA and Kruskal-Wallis data analyses found significance among the data. The Tukey HSD post hoc test revealed a significant difference between the accuracy of signs and symptoms to treatment variables (p = 0.045). Analysis by the Mann-Whitney U test also determined that a significant difference was evident between the accuracy of signs and symptoms when compared with treatment (p = 0.022). CONCLUSIONS: The treatments presented in the twelve episodes evaluated were determined to be more accurate than the show's description of the patient's presenting signs and symptoms.

Rare earth ion doped glasses find applications in optical and photonic devices such as optical windows, laser, and optical amplifiers, and as model systems for immobilization of nuclear waste. Macroscopic properties of these materials, such as luminescence efficiency and phase stability, depend strongly on the atomic structure of these glasses. In this thesis, I have studied the atomic level structure of rare earth doped silicate and aluminophosphate glasses by using molecular dynamics simulations. Extensive comparisons with experimental diffraction and NMR data were made to validate the structure models. Insights on the local environments of rare earth ions and their clustering behaviors and their dependence on glass compositions have been obtained. In this thesis, MD simulations have been used to investigate the structure of Eu2O3-doped silica and sodium silicate glasses to understand the glass composition effect on the rare earth ions local environment and their clustering behaviors in the glass matrix, for compositions with low rare earth oxide concentration (~1mol%). It was found that Eu–O distances and coordination numbers were different in silica (2.19-2.22 Å and 4.6-4.8) from those in sodium silicate (2.32 Å and 5.8). High tendencies of Eu clustering and short Eu-Eu distances in the range 3.40-3.90 Å were observed in pure silica glasses as compared to those of silicate glasses with much better dispersed Eu3+ ions and lower probability to form clusters. The results show Eu3+ clustering behavior dependence on the system size and suggest for low doping levels, over 12,000 atoms to obtain statistical meaningful results on the local environment and clustering for rigid silica-based glasses. The structures of four cerium aluminophosphate glasses have also been studied using MD simulations for systems of about 13,000 atoms to investigate aluminum and cerium ion environment and their distribution. P5+ and Al3+ local structures were found stable while those of Ce3+ and Ce4+ ions, through their coordination numbers and bond lengths, are glass composition-dependence. Cerium clusters were found in the high cerium glasses.P5+ coordination numbers around cerium revealed the preference of phosphorus ions in the second coordination shell. Total structure factors from MD simulations and experimental diffraction results show a general agreement from comparison for all the cerium aluminophosphate glasses and with compositional changes up to 25 Å-1. Aluminum enters the phosphate glass network mainly as AlO4 and AlO5 polyhedra only connected through corner sharing to PO4 tetrahedra identified by Q11(1 AlOx), Q12(2 AlOx), Q21(1 AlOx), and Q22(2 AlOx) species.

The number of three-dimensional structures of potential protein targets available in several platforms such as the Protein Data Bank is subjected to a constant increase over the last decades. This observation should be an additional motivation to use structure-based methodologies in drug discovery. In the recent years, different success stories of Structure Based Drug Design approach have been reported. However, it has also been shown that a lack of druggability is one of the major causes of failure in the development of a new compound. The concept of druggability can be used to describe proteins with the capability to bind drug-like compounds. A general consensus suggests that around 10% of the human genome codes for molecular targets that can be considered as druggable. Over the years, the protein druggability was studied with a particular interest to capture structural descriptors in order to develop computational methodologies for druggability assessment. Different computational methods have been published to detect and evaluate potential binding sites at protein surfaces. The majority of methods currently available are designed to assess druggability of a static structure. However it is well known that sometimes a few local rearrangements around the binding site can profoundly influence the affinity of a small molecule to its target. The use of techniques such as molecular dynamics (MD) or Metadynamics could be an interesting way to simulate those variations. The goal of this thesis was to design a new computational approach, called JEDI, for druggability assessment using a combination of empirical descriptors that can be collected ‘on-the-fly’ during MD simulations. JEDI is a grid-based approach able to perform the druggability assessment of a binding site in only a few seconds making it one of the fastest methodologies in the field. Agreement between computed and experimental druggability estimates is comparable to literature alternatives. In addition, the estimator is less sensitive than existing methodologies to small structural rearrangements and gives consistent druggability predictions for similar structures of the same protein. Since the JEDI function is continuous and differentiable, the druggability potential can be used as collective variable to rapidly detect cryptic druggable binding sites in proteins with a variety of MD free energy methods.

No description available.

Traditional lawn care for suburban American households merits examination from both ecological and social perspectives. Such practices have potentially detrimental consequences on human and natural systems that will continue to grow with urbanization. Consequently, further characterization of the complex, multiscale processes in which lawn management decisions are rooted could enhance methods for encouraging the adoption of alternatives to industrialized lawn care. This study conceptualizes mesoscale, or neighborhood-level, influences on watering, fertilizing, and mowing practices in Baltimore city, through a modified grounded theory analysis of key informant interviews in Mount Washington, Westfield, and Park Circle. This study finds that mesoscale processes play a significant role in the residential lawn care of these neighborhoods. The applicable processes vary by the community’s social cohesion and tenets. As socioeconomic status and social cohesion increases within the study area, the influence of informal authority in residential lawn care increases. Results demonstrate potential policy implications. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2019. / FAU Electronic Theses and Dissertations Collection

In this work flow properties of dendrimers are studied with the aid of molecular simulations. For the first time the results of the nonequilibrium molecular dynamics simulations of the dendrimers in the melt are reported. Molecules are modelled at the coarse-grained level using the bead-spring model. The objective of this research is to analyse the influence of the molecular topology in the macroscopic flow behaviour of the melts. Systems of dendrimers of generations 1 to 4 undergoing planar shear are compared to the melts composed of linear chain polymers. The internal structure and shape of dendrimers is extensively analysed. The response of the molecules to the shearing in the form of stretching and alignment is studied. The correlation between the onset of shear thinning and the onset of deformation of molecules is observed. The changes in the fractal dimensionality of dendrimers due to shearing are also analysed. Dendrimers, due to their highly branched structure and compact globular conformations in the melt, are found to behave differently when sheared, compared to traditional linear polymers. Unlike linear polymers, they do not undergo transition form the Rouse to the reptation regimes. This effect is explained in terms of the suppressed entanglement between molecules. Moreover, dendrimers when compared to linear chain systems exhibit lower Newtonian viscosity, onset of the shear thinning at higher strain rates, and less pronounced shear thinning in the non-Newtonian regime. They can be used as rheology modifiers, as it is shown in the preliminary results obtained from the simulations of the dendrimers-linear polymer blends. In agreement with other theoretical and experimental studies, dendrimers in the melt are found to have compact space-filling structure with terminal groups distributed throughout the interior of the molecule. Suggestions for the further study of dendrimers via molecular simulations are made.