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Analyse moléculaire in situ d'un noyau cométaire : Développement et évaluation des performances d'un système de chromatographie en phase gazeuse pour la mission RosettaSzopa, Cyril 19 December 2001 (has links) (PDF)
La composition chimique des comètes revêt un intérêt du point de vue de la chimie prébiotique, mais également de la formation et de l'évolution du système solaire. Cette thèse présente la première étape d'un programme de longue durée dont l'objectif final est la détermination de la composition chimique du noyau cométaire.<br />Parmi les différentes méthodes employées jusqu'à aujourd'hui, l'analyse in situ est la seule capable de nous procurer des informations directes sur le noyau cométaire. C'est cette approche que nous avons choisi d'employer en contribuant à l'expérience COmetary Sampling And Composition (COSAC). Cette dernière fait partie des expériences embarquées dans la sonde Rosetta dédiée à l'analyse d'une comète et de son environnement. Compte tenu du nombre important de composés probablement présents dans le noyau cométaire et de la robustesse de cette technique analytique, la chromatographie en phase gazeuse (CPG) apparaît comme la plus appropriée pour l'identification et la quantification des composés présents dans le noyau cométaire. Nous avons donc développé un sous-système chromatographique qui fera partie intégrante de l'expérience COSAC.<br />La principale tâche de ce travail a été de concevoir la partie séparative de ce système, constituée de colonnes chromatographiques connectées en parallèle. Cette partie a été développée en vue de la séparation et de l'identification d'une large gamme de composés d'intérêt cométaire initialement identifiés, allant des composés les plus légers (gaz nobles) jusqu'à des espèces organiques de poids moléculaire élevé (HAP). A cette fin, un travail expérimental a été mené pour comparer les propriétés analytiques (sélectivité, efficacité) des nombreuses colonnes chromatographiques candidates, dans les conditions de température in situ (isotherme comprise entre 30°C et 60°C). Cette étude, associée à la prise en compte de contraintes opératoires (présence d'eau, faible consommation de gaz vecteur, robustesse des colonnes...), a permis d'aboutir à la sélection et à l'optimisation des caractéristiques de 5 colonnes chromatographiques différentes. Cette combinaison correspond au nombre minimal de colonnes permettant de répondre aux objectifs du système chromatographique.<br />Une fois les colonnes de l'expérience sélectionnées, elles ont été soumises aux différentes contraintes liées à l'instrumentation spatiale (vibrations, cycles de température) et à l'environnement spatial (pression réduite, radiations) pour tester leur robustesse. Les résultats montrent que les performances de ces colonnes ne sont affectées ni par ces tests, ni par la présence d'eau dans l'échantillon, prouvant ainsi leur capacité à être utilisées dans le système chromatographique.<br />Ensuite, les performances réelles de ce système ont été évaluées à l'aide d'un outil de laboratoire reproduisant l'expérience COSAC (colonnes, détecteurs) et les conditions opératoires in situ (température, pression externe). Cette étude a permis de montrer que les propriétés analytiques du système ne sont pas significativement altérées comparativement à celles observées à pression atmosphérique en sortie de colonne, et que le gain de vitesse entraîné par la présence d'une pression réduite était bénéfique par la réduction du temps d'analyse. De plus, la pression en tête de colonne optimale de l'expérience a pu être fixée (150 kPa). Nous avons également montré que l'expérience devrait permettre d'identifier environ 75% des composés initialement ciblés.<br />Enfin, la sensibilité du système (colonne+détecteur) a été évaluée en mesurant la quantité minimale détectable d'un composé présent dans un mélange analysé. Elle est comprise entre 10-11 mol et 10-12 mol, ce qui correspond à un rapport de volume de 1 ppm dans le cas le plus favorable où il y a suffisamment d'échantillon gazeux pour remplir complètement la boucle d'échantillonnage. Ce dernier résultat permet de conclure que le système développé permet l'analyse de composés traces présents dans le noyau cométaire et que sa sensibilité est plus importante que celle des observations spectroscopiques de la coma (environ 0,1%).<br />Au delà du travail expérimental de mise en œuvre de ce système chromatographique, nous avons pu également montrer que le couplage d'une des colonnes avec les techniques préparatives des échantillons de COSAC devrait permettre d'analyser des espèces chimiques qui ne pouvaient pas l'être par CPG directe (acides aminés), ou de mettre en évidence des composés réfractaires à partir de leurs produits de dégradation thermique (poly-HCN). Enfin, nous présentons les premiers travaux expérimentaux et théoriques développés en vue de l'interprétation des futures données collectées par l'instrument de vol.
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Systematic Variability of Soil Hydraulic Conductivity Across Three Vertisol CatenasRivera, Leonardo Daniel 2010 August 1900 (has links)
Soil hydraulic properties, such as saturated hydraulic conductivity (Ks), have high
spatial variation, but little is known about how to vary a few measurements of Ks over an
area to model hydrology in a watershed with complex topography and multiple land
uses. Variations in soil structure, macropores (especially in soil that shrink and swell),
land use, and soil development can cause large variations in Ks within one soil type.
Characterizing the impacts of soil properties that might vary systematically with land use
and terrain attributes on Ks rates would provide insight on how management and human
activity affect local and regional hydrology. The overall objective of this research was
to develop a strategy for using published infiltration and Ks measurements by the Natural
Resources Conservation Service for watershed hydrology applications in a Vertisol, and
to extend this knowledge toward developing recommendations for future infiltration
measurements. To achieve this goal, soil infiltration measurements were collected
across three catenas of Houston Black and Heiden clays (fine, smectitic, thermic Udic
Haplusterts) under three land uses (improved pasture, native prairie, and conventional tillage row crop). Measurement locations were selected to account for variation in
terrain attributes.
Overall, Ks values were not significantly different across different landscape
positions; however, in fields under similar land uses, Ks values were found to be lower in
the footslope positions and higher in the backslope positions. The pedotransfer function,
ROSETTA, provided estimates of 64 percent of the overall variability in Ks while also
providing accurate estimates of the mean of Ks when particle size distribution and bulk
density are used as inputs in the model. Through the use of multiple regression analysis,
soil antecedent water content, bulk density, clay content, and soil organic carbon along
with two indicator variables for the catenas were highly correlated (r2 = 0.59) with Ks.
The indicator variables explained 17 percent of the variation in Ks that could not be explained
by measured soil properties. It is recommended that when NRCS measures Ks on
benchmark soils, especially high clay soils, that they collect particle size distribution,
bulk density, organic carbon, and antecedent water content data.
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Použití programu Rosetta k odhadu retenčních čar půdní vlhkosti z experimentální plochy Bohaté Málkovice / Using program Rosetta to estimate of soil moisture retention curves from experimental size Bohaté MálkoviceČermák, Petr January 2015 (has links)
Hydraulic characteristics are the most important properties of soil, i.e. retention curve of soil moisture and hydraulic conductivity. Hydraulic conductivity of soil characterizes the ability of the soil to conduct water. Retention curve expresses the relationship between moisture and moisture potential of soil. The running of retention curve is influenced by many factors, eg. grain size and mineralogical composition, content of humus, reduce bulk density and structure of soil. Measurement of retention curves takes a lot of time and money in laboratory conditions therefore pedotransfer functions seem to be an alternative solution. The thesis aims to estimate moisture retention curves of soil in a selected area of interest in South Moravia using program Rosetta (Schaap, 2003). Data of granularity (% content of clay, sand and dust), bulk density of soil and hydrolimits field water capacity and wilting point were used as predictors in individual models of program Rosetta. Data of grain were matched by FAO / USDA system. Retention curves of soil moisture were measured on a sand tank and overpressure devices. The measured retention curves were parameterized by RETC program. Estimated retention curves were graphically compared with measured to determine the quality of the estimate. The accuracy of the estimate was assessed by correlation coefficient R of determination coefficient R2 and standard error SMRE. Usability own derivatives pedotransfer functions is hard to say due to the size of the input data file. I would recommend further verification of data at the other localities in south Moravia.
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Veratridine Can Bind to a Site at the Mouth of the Channel Pore at Human Cardiac Sodium Channel NaV1.5Gulsevin, Alican, Glazer, Andrew M., Shields, Tiffany, Kroncke, Brett M., Roden, Dan M., Meiler, Jens 20 January 2024 (has links)
The cardiac sodium ion channel (NaV1.5) is a protein with four domains (DI-DIV), each
with six transmembrane segments. Its opening and subsequent inactivation results in the brief rapid
influx of Na+ ions resulting in the depolarization of cardiomyocytes. The neurotoxin veratridine
(VTD) inhibits NaV1.5 inactivation resulting in longer channel opening times, and potentially fatal
action potential prolongation. VTD is predicted to bind at the channel pore, but alternative binding
sites have not been ruled out. To determine the binding site of VTD on NaV1.5, we perform docking
calculations and high-throughput electrophysiology experiments in the present study. The docking
calculations identified two distinct binding regions. The first site was in the pore, close to the
binding site of NaV1.4 and NaV1.5 blocking drugs in experimental structures. The second site was at
the “mouth” of the pore at the cytosolic side, partly solvent-exposed. Mutations at this site (L409,
E417, and I1466) had large effects on VTD binding, while residues deeper in the pore had no effect,
consistent with VTD binding at the mouth site. Overall, our results suggest a VTD binding site
close to the cytoplasmic mouth of the channel pore. Binding at this alternative site might indicate an
allosteric inactivation mechanism for VTD at NaV1.5
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L'architecture domestique de Rashîd du XVIème siècle au XIXème siécle (Étude comparatives) / Residential Buildinq Pudonq RashidiAbou Bakr, Salwa 11 December 2009 (has links)
Après le Caire, Rashîd est l’une des villes d’Égypte ayant gardé un important héritage architectural et urbain. Tout au long de son histoire elle a joué un rôle considérable dans le Delta, notamment pendant la période ottomane. Elle a connu tout le long de cette partie de son histoire un essor économique et commercial intéressant à expliquer les raisons. Elles sont multiples, mais particulièrement sa situation géographique dans la région qui a joué le rôle le plus prépondérant. Le fait qu’elle soit la ville égyptienne la plus proche à la fois d’Istanbul et de l’Europe lui a permis de développer avec celles-ci des relations économiques et commerciales prospères qui ont induit un véritable développement urbain de la ville. Rashîd s'est ainsi dotée d’un style architectural particulier et d’un nombre important de constructions domestiques. / Rashid City is considered once of the richest Egyptian cities in term of Arabian Monuments; it comes second in its monumental wealth after the city of Cairo. Rashid city keeps until this moment a number of monuments which were built during the Ottoman era, on top of which comes a number of monumental houses (20 houses) which are unique in style.Rashaid city had also played a remarkable role in aspects of history, culture, architecture, and art, which had placed such city in high regard among the Arab cities. Arab cities joined Al- rasheed in founding such unique buildings.Building were affected in both shape and essence by geographical, economic, political, cultural, and religious factors found in such era; thus buildings appeared to have mostly similar shapes in some cities, while they appeared to be different in others. Such buildings were also buit using similar materials in some cities, while using different ones in others; however all the buildings were built to provide a shelter for humans in order to achieve their privacy, and protection against any natural or man-made dangers.Thus such unique architecture which took notice of essence rather than appearance – the Arabian housing architecture – had emerged to fulfill all these constant human needs regardless of time or place.Such remaining architectural relics must be placed under athorough historical and technical study, so that we would have the sufficient expertise needed to contribute in preserving such historical buildings.
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Spectrophotometric properties of the nucleus of the comet 67P/Churyumov-Gerasimenko observed by the ROSETTA spacecraft / Propriétés spectrophotométriques du noyau de la comète 67P/Churyumov-Gerasimenko observée par la sonde ROSETTAJasinghege Don, Prasanna Deshapriya 12 September 2018 (has links)
Cette thèse s'inscrit dans le cadre de la mission spatiale Rosetta et porte sur les propriétés spectrophotométriques de la comète 67P/Churyumov-Gerasimenko à l’aide de l’instrument OSIRIS. Cet instrument est composé de deux caméras pour les observations du noyau et de la coma de la comète. Elles permettent d’acquérir des images avec des filtres qui opèrent dans la gamme du proche UV au proche IR. Dans un premier temps, j'ai analysé les courbes spectrophotométriques des taches claires qui sont apparues sur le noyau de la comète. Une étude comparative de celles-ci grâce aux données du spectro-imageur VIRTIS a ainsi permis de constater que les taches claires sont liées à la glace de H2O. Dans un second temps, j’ai entrepris une étude spectrophotométrique de la région Khonsu, qui a mis en évidence les variations saisonnières de la pente spectrale de différents terrains. Par la suite, j’ai élargi mon analyse des taches à tout le noyau de la comète. J’ai détecté plus de 50 taches claires dues à la présence de glace de H2O et j’ai produit une carte pour repérer leurs emplacements sur le noyau, afin d’étudier plus en détail leur répartition et leur évolution au cours de temps. Ceci m’a permis d’identifier quatre types de taches regroupés en fonction de leur morphologie et de constater qu'elles sont dues à différentes sources d'activité cométaire. / This thesis is based on the spectrophotometric properties of the comet 67P/Churyumov-Gerasimenko, using the OSIRIS instrument of Rosetta space mission. Composed of two scientific cameras to observe the nucleus and the coma of the comet, OSIRIS images are acquired with multiple filters, that span the near-UV to near-IR wavelength range. They were used to study the spectrophotometric curves of the exposed bright features that appeared on the surface of the cometary nucleus, leading to a comparative study, that was carried out in collaboration with the VIRTIS spectro-imager aboard Rosetta, that demonstrated, that these exposures are related to H2O ice, using its absorption band located at 2 microns. The thesis further details a spectrophotometric study of the Khonsu region in the southern latitudes of the comet, where the seasonal variation of the spectral slope of different types of terrains is explored. Finally, the results of an extended survey of exposed bright features are presented. More than 50 individual features are presented under four morphologies along with an albedo calculation, suggesting that different activity sources are responsible for their appearance on the nucleus.
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Eficiência e direito: o papel da maximização da riqueza na análise econômica do direito a partir da obra de Richard PosnerOLIVEIRA, Erickson Araújo Santana de 15 February 2016 (has links)
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Previous issue date: 2016-02-15 / O propósito desta pesquisa é descrever e caracterizar a evolução do conceito de maximização da riqueza na obra de Richard A. Posner. Diversos trabalhos anteriores ressaltam a existência de "fases" no pensamento do autor paradigma, enquanto este trabalho busca encontrar um motivo condutor que permeie toda sua obra e que represente sua unidade. Para tanto, o trabalho acompanha a evolução do pensamento do autor-paradigma, usando o conceito de eficiência como chave para melhor compreensão de sua obra, desde a identificação deste como "pedra de Rosetta" para compreensão do common law, passando por sua utilização como critério normativo, até a sua acomodação no pragmatismo cotidiano proposto pelo autor. Por extrapolação, o trabalho dialoga diretamente com o movimento da Análise Econômica do Direito, da qual o autor-paradigma foi e continua a ser figura chave, procurando encontrar uma forma de racionalidade comum a todo movimento que pudesse ser utilizada para avaliação de políticas públicas. Por fim, trata da utilização da teoria macroeconômica como um novo vetor da Análise Econômica do Direito. / The purpose of this research is to describe the evolution of the wealth maximization concept by looking at the work of Richard A. Posner. Several prior researches emphasize the existence of "phases" in his work, while this research was designed to identify a "leitmotiv" that would pervade all his work and represent its unity. To that effect, this dissertation follows the evolution of Posner’s work, using the concept of economic efficiency as key to better understand his work, from the identification of such concept as a "Rosetta stone" of the common law, passing it as a normative criterion, to its accomodation in the everyday pragmatism put forth by the author. This dissertation, by extrapolation, opens a direct dialogue with the Law and Economics movement, of which the author was and continues to be a key figure, seeking a form of rationality that is common to all the movement e that could be used as a mean to evaluate public policy. At last, it focus on the usage of macroeconomic theory as a new vector for Economic Analysis of Law.
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Stanovení hydraulických charakteristik půdy ve vybraném zájmovém území / Determination of hydraulic characteristics of soil in a selected areaSalač, Jan January 2018 (has links)
The diploma thesis is focused on issues of measurement and evaluation of hydraulic characteristics of soil. In the literary research, the definitions of hydraulic conductivity and retention curve of soil moisture, their measurements in laboratory and field conditions and the prediction of these characteristics by using of pedotransfer functions. In the practical part of the diploma thesis, an evaluation of the hydraulic conductivity of soil from the experimental areas near the village Bohaté Málkovice. Two-cylindrical and mini-disc infiltration meters were used for field measurements, and a constant-gradient permeameter was used in the laboratory. Physical and empirical equations were used to evaluate the hydraulic conductivity. The results were processed numerically, tabulated and then compared.
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Bioinformatický nástroj pro predikci struktury proteinů / Bioinformatics Tool for Protein Structure PredictionPlaga, Michal January 2016 (has links)
The goal of this thesis is test and comparation of the offline tools for prediction of protein structure and creation of metaprediktor, which allows the user to select the appropriate tool, according to given parameters. Testing tool is based on a dataset of proteins, which is based on the SCOP database and it is trying to be as balanced as possible to include proteins from different families and thus could best evaluate individual tools. The results of this thesis are requirements of metaprediktor and also which data and settings can be allowed and processed and how it will be implemented.
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Stanovení hydraulických charakteristik půdy ve vybrané lokalitě / Determination of soil hydraulic characteristics in the selected locationStoklásková, Adéla January 2012 (has links)
This thesis deals with direct and indirect determination of soil hydraulic characteristics (retention curve and hydraulic conductivity) in the locality of Bohaté Málkovice. For laboratory determination of soil moisture retention curve is used sand tank and pressure relief device. For the indirect determination of soil hydraulic characteristics is used computer software Rosetta, which includes 5 models of pedotransfer functions. For estimatiton of retention curves are applied previously derived pedotransfer function (continuous parametric PTF and point PTF).
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