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Percursos de leitura em FLE a distânciaKaspary, Cíntia Voos January 2012 (has links)
Esta pesquisa propõe uma análise do uso de ferramentas digitais, em especial do mapa mental, através de uma abordagem sócio-interacionista da leitura em FLE - Francês como língua estrangeira - como alternativa diferenciada de ensino- aprendizado. A partir deste preceito, foram discutidos aspectos do sócio-interacionismo, o conceito de letramentos e os gêneros do discurso para refletir sobre a aprendizagem da leitura em FLE através de tarefas que favoreçam situações de letramentos em ambientes virtuais de aprendizagem. A instrumentalização do processo interativo se deu através da criação de um curso de leitura em FLE dentro de um ambiente virtual de aprendizagem baseado em tarefas e procedimentos pedagógicos que envolveram os conceitos do sócio-interacionismo vygotskyano, assim como os critérios para desenvolvimento das tarefas que visem a letramentos em FLE. Os dados obtidos para esta investigação originaram-se das interações ocorridas durante o desenvolvimento do curso “Percursos de leitura em FLE” na modalidade EAD no Núcleo de Ensino de Línguas em Extensão da UFRGS que teve a duração de quarenta e oito horas. Além da análise das interações, foram produzidos dois questionários a fim de contextualizar os aprendizes participantes e identificar suas expectativas e objetivos relacionados à realização do curso. Ao final desta pesquisa, foi possível observar que as interações entre os aprendizes e o seu envolvimento na realização das tarefas favoreceram sua autonomia e interação, pois negociaram situações e ideias sem necessariamente a intervenção do professor. Além disso, pode-se observar que uma preparação pedagógica consistente, com base nos princípios teóricos estudados, oportunizou aos aprendizes condições de desenvolvimento de sua compreensão leitora em um ambiente virtual de aprendizagem. / Cette recherche se propose de réaliser une analyse concernant l'usage des outils numériques, spécialement de la carte mentale, à travers l'approche sociointeractioniste de la lecture en FLE comme une alternative distinguée d'enseignement-apprentissage.À partir des contributions du sociointeractionisme, de l'idée de littératies et de genres du discours, ce travail a proposé des alternatives qui favorisent la réflexion à propos de l'enseignement-apprentissage de FLE en utilisant des tâches en ENA ( Environemment Numérique d’ Apprentissage) qui favorisent des littératies.Le projet s’ est produit à travers des tâches et des procédures pédagogiques qui ont utilisé les concepts du sociointeractionisme vygotskyen et des critères pour l’ organisation des tâches qui visent à la construction des littératies en FLE . Les données obtenues dans cette recherche proviennent des interactions dans le cours, « Percursos de Leitura en FLE », à distance, soutenu par le Núcleo de Ensino de Línguas em Extensão/ UFRGS ayant une durée de quarante-huit heures. En plus d'analyses d'interaction, deux questionnaires ont été réalisés afin de connaître les apprenants, leurs souhaits et leurs objectifs par rapport au cours. À la fin de cette recherche, il est possible d'observer que les interactions entre les apprenants et leurs investissements dans la réalisation des tâches ont démontré de l’ autonomie et une intense interaction. Ils étaient toujours près à négocier et à échanger des idées, leurs expériences sans nécessairement l’ intervention du professeur. Finalement, il est possible d’observer que la planification adéquate des tâches inspirées des principes théoriques a favorisé le développement des capacités de compréhension lectrice dans un environnement d'apprentissage qui intègre des outils numériques.
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Approche écosystémique des énergies marines renouvelables : étude des effets sur le réseau trophique de la construction du parc éolien au large de Courseulles-sur-Mer et du cumul d'impacts / Ecosystem approach of marine renewable energy : study of the impact on the food web of the construction of the Courseulles-sur-Mer’s offshore wind farm and cumulative impactsRaoux, Aurore 27 November 2017 (has links)
Dans le cadre de la transition énergétique, le gouvernement Français prévoit la constructionde huit parcs éoliens en mer (offshore) le long des côtes Manche-Atlantique parmi lesquels le futurparc éolien au large de Courseulles-sur-mer. A ce jour, il n’existe pas d’étude globale et intégrée deseffets de la construction et de l’exploitation de ces parcs sur l’écosystème. L’innovation principale decette thèse a donc été de poser les bases d’une approche écosystémique des Energies MarinesRenouvelables (EMR) à travers l’exemple du futur parc éolien de Courseulles-sur-mer. Pour ce faire,une combinaison d’outils de modélisation a été utilisée afin de : 1) caractériser le fonctionnement etla structure de l’écosystème du site d’implantation du parc ; 2) tester des scénarios d’évolutionpossible du fonctionnement trophique du système. Ainsi, un modèle de réseau trophique et troisscénarios ont été construits afin d’analyser les conséquences de l’effet récif et réserve générées par leparc sur l’écosystème. Les indices de l’analyse des réseaux écologiques ainsi que d’autres indices telsque le niveau trophique moyen ont été analysés afin de caractériser le fonctionnement du système.Toutefois, conscient que cet écosystème est menacé par de multiples pressions, il estnécessaire de comprendre comment ces activités humaines vont interagir entre elles et quelles sontleurs conséquences sur l’écosystème dans un contexte de changements globaux. Ainsi, une visionglobale des impacts cumulés a également été développée grâce à un autre type de modélisation appelé'modélisation qualitative’ ou en ‘digraphe orienté’. Les résultats ont mis en évidence des changementsdans la structure et le fonctionnement de l’écosystème après la mise en place du parc éolien. Lesrésultats de ces modèles pourraient être utilisés dans la définition de mesures de suivi aprèsl’installation du parc et dans l’évaluation de la nécessité de mettre en place des mesures decompensation. Enfin, les modèles qualitatifs pourraient également servir d’outils de communicationavec le public et ainsi permettre une meilleure appropriation des projets EMR. / As part of the energy transition, the French government is planning the construction of eightOffshore Wind Farms (OWF) along the English Channel and Atlantic coasts including the Courseulles-sur-mer OWF. Until now, there is no holistic study on the OWF construction and operation effects onan ecosystem taken as a whole. This thesis is the first study to lay the foundations for an ecosystemapproach of Marine Renewable Energy (MRE) through the Courseulles-sur-mer OWF example. For thata combination of innovative modelling tools was applied to 1) characterise the ecosystem structureand functioning before the OWF construction; 2) simulate the impacts of this future OWF on theecosystem structure and functioning. A food-web model and three scenarios were constructed toinvestigate the “reef” and “reserve” effects induced by the OWF on the ecosystem. Ecological NetworkAnalysis indices, other ecosystem attributes and Mean Trophic Level were derived to investigate theecosystem health and state.However, being aware that this ecosystem is threatened by multiple perturbations, there is aneed to understand how human activities interact to influence ecosystem functioning in a long termclimate change context. Thus, a holistic view of cumulated impacts on the Courseulles-sur-mer’ecosystem through the use of an oriented signed digraph was also developed. Results highlighted acombination of significant changes in the food-web structure and ecosystem functioning. These resultscan play a vital role in both decision making by improving long term planning for the marineenvironment but also as tool for communication with the public and so contribute to a betteracceptability of MRE project.
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Efeito do Yo Jyo Hen Shi Ko (YHK) no metabolismo lipídico na esteatohepatite experimental / Evaluation of Yo Jyo Hen Shi Ko (YHK) in hepatic lipid metabolism in experimental steatohepatitisPereira, Isabel Veloso Alves 19 May 2010 (has links)
A Doença Hepática Gordurosa Não Alcoólica (DHGNA) é atualmente uma das formas mais comuns de doença hepática, e está diretamente relacionada com a obesidade. Estudos indicam uma prevalência por volta de 30% na população ocidental e 11% na população oriental. A DGHNA possui um largo espectro abrangendo desde casos de esteatose simples sem inflamação, até casos com esteatohepatite e fibrose, podendo evoluir para cirrose e carcinoma hepatocelular. A fisiopatogênese da DHGNA é baseada em múltiplos eventos: resistência insulínica, aumento da lipólise periférica, aumento da síntese de novo de lipídeos, estresse oxidativo, endotoxemia crônica no desencadeamento da inflamação e fibrose entre outros. A etapa inicial caracteriza-se pelo acúmulo de ácidos graxos no hepatócito, suplantando sua capacidade de metabolização e exportação conseqüente à ação lipogênica da insulina, desta forma o metabolismo de ácidos graxos está intimamente ligado ao desenvolvimento da DHGNA. O Yo Jyo Hen Shi Ko (YHK) é um composto natural usado na medicina japonesa para tratamento de doenças hepáticas e apresenta propriedades antioxidantes, antiinflamatórias e hipolipemiantes. O presente estudo teve como objetivo avaliar o efeito do YHK no metabolismo hepático de lipídeos. Para tanto, foram utilizados camundongos obesos (ob/ob) com esteatohepatite não alcoólica (ENA) induzida por dieta deficiente em colina e metionina (DCM) e foram analisados no tecido hepático, genes relacionados com a síntese de novo de lipídeos (SREBP1c, FASn), genes relacionados com a oxidação e exportação de lipídeos (CPT1a e SCD-1, MTP), assim como genes relacionados com o armazenamento de lipídeos (Perilipina e ADFP). O YHK apresentou um efeito citoprotetor hepático com melhora dos parâmetros histológicos neste modelo experimental de ENA. Associadamente, houve redução na expressão de genes relacionados à síntese de novo como SREBP e da FASn, quando se comparou o grupo tratado com DCM+YHK com o grupo não tratado DCM. Em contrapartida, houve aumento na expressão da MTP e da SCD-1 ocasionando uma maior exportação de triglicerídeos hepáticos nos animais que utilizaram o YHK. Ainda, o YHK modulou as proteínas Perilipina e ADFP. Por outro lado, não houve modificação na oxidação de lipídeos.. Conclui-se que o YHK pode ser uma droga promissora no tratamento da DHGNA, já que age modulando genes envolvidos na síntese e exportação de lipídeos hepáticos, reduzindo o acúmulo de gordura no hepatócito / Nonalcoholic fatty liver disease (NAFLD) is currently one of the most common forms of liver disease, related directly to the increase of obesity in the world. Previous studies indicate a prevalence of around 30% in the western population and 11% in the eastern. This disease covers cases from simple steatosis without inflammation to cases of steato hepatitis (NASH) and fibrosis and it may lead to liver cirrhosis and hepatocellular carcinoma. The pathophysiology of NAFLD is based on multiple events: insulin resistance, increased peripheral lipolysis, increased de novo lipogenesis, oxidative stress, endotoxemia in triggering chronic inflammation and fibrosis and others. The initial stage of the disease is characterized by the accumulation of fatty acids in hepatocytes caused by the lipogenic action of insulin. This condition results in the surpassing of the cells ability to metabolize and export. This way, the metabolism of fatty acids is closely linked to the development of NAFLD. The Yo Jyo Hen Shi Ko (YHK) is a natural compound used in Japanese medicine for the treatment of liver disease and it has antioxidant, anti-inflammatory and lipid lowering properties. This study aimed to evaluate the effect of YHK in the hepatic metabolism of lipids. An experimental model was designed using obese mice (ob/ob) affected by NASH induced by a deficient diet in choline and methionine (MCD). Then, genes from its hepatic tissue related to de novo lipogenesis (SREBP1c, FASN), to lipid oxidation and exportation (CPT1A and SCD-1, MTP) as well as genes related to lipid storage (Perilipin and ADFP) were analyzed. The YHK presented a cytoprotective effect, improving the hepatic histological parameters in this experimental model. Additionally, when comparing the group treated with MCD + YHK (diet + YHK) to the untreated MCD group (diet) there was a reduction in the expression of genes related to de novo synthesis like SREBP1c and FASn. However, an increased expression of MTP and SCD-1 were observed leading to a greater liver exportation of fatty acids in animals that were treated with YHK. Moreover, the YHK modulated the proteins Perilipin and ADFP. On the other hand, there was no changing in lipid oxidation. In summary, the YHK can be a promising drug for the treatment of NAFLD, as it acts by modulating genes involved in the synthesis and exportation of hepatic lipids, reducing the accumulation of fat in hepatocytes
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Conformationally Constrained Nucleosides : Design, Synthesis, and Biochemical Evaluation of Modified Antisense OligonucleotidesVarghese, Oommen P. January 2007 (has links)
This thesis is concerned with synthesis, structure and biochemical analysis of chemically modified oligonucleotides with potential therapeutic applications. The three types of chemical modifications described here are: (a) A North-East locked 1',2'-azetidine nucleoside (b) A North locked 2',4'-cyanomethylene bridged nucleoside and (c) A 2',4'-aza-ENA-T nucleoside. The synthesis of the 1',2'-azetidine fused nucleosides was described using two different approaches. A highly strained 2',4'-cyanomethylene locked nucleoside was synthesized but could not be converted to the phosphoramidite derivative due to instability during derivatization. The key cyclization step in the aza-ENA-T nucleoside synthesis gave rise to two separable diastereomers due to chirality at the exocyclic nitrogen. Conversion of diastereomer 55 to 56 occurred with a large free energy of activation (ΔG‡ = 23.4 kcal mol-1 at 298 K in pyridine-d5). Of the two isomers the equatorial NH product was more stable than the axial one due to reduced 1,3 diaxial interactions. As a result, all NH axial product was converted to the equatorial isomer during subsequent steps in the synthesis. NMR and ab initio experiments confirmed the North-East structure of the 1',2'-azetidine locked nucleoside and North conformation of aza-ENA-T locked nucleosides with a chair conformation of the piperidine ring. The amino modified nucleosides were incorporated into different positions of a 15mer oligonucleotide. The azetidine modified AONs did not form stable duplexes with complementary RNA (ΔTm ~-1 to -4 °C), but they performed better than previously synthesized isosequential 1',2'-oxetane modified oligonucleotides. The 2',4'-aza-ENA-T modified oligonucleotide, on the other hand, showed excellent target affinity with complementary RNA (ΔTm ~+4 °C). The azetidine and aza-ENA-T modified oligonucleotides showed significant stability in the presence of human serum and snake venom phosphodiesterase (3'-exonuclease) as compared to the unmodified native sequence. The singly modified 15mer oligonucleotides were also subjected to RNase H promoted digestion in order to evaluate their potential as effective antisense agents. The effective enzyme activity (kcat/Km) was found to be lower in the modified AONs due to reduced enzyme-substrate binding. However, the catalytic activity of RNase H with these modified-AON:RNA duplexes were higher than observed with the native duplex.
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Conformationally Constrained Nucleosides, Nucleotides and Oligonucleotides : Design, Synthesis and PropertiesHoncharenko, Dmytro January 2008 (has links)
This thesis is based on six original research publications describing synthesis, structure and physicochemical and biochemical analysis of chemically modified oligonucleotides (ONs) in terms of their potential diagnostic and therapeutic applications. Synthesis of two types of bicyclic conformationally constrained nucleosides, North-East locked 1',2'-azetidine and North locked 2',4'-aza-ENA, is described. Study of the molecular structures and dynamics of bicyclic nucleosides showed that depending upon the type of fused system they fall into two distinct categories with their respective internal dynamics and type of sugar conformation. The physicochemical properties of the nucleobases in the conformationally constrained nucleosides found to be depended on the site and ring-size of the fused system. The incorporation of azetidine modified nucleotide units into 15mer ONs lowered the affinity toward the complementary RNA. However, they performed better than previously reported isosequential 1',2'-oxetane modified analogues. Whereas aza-ENA-T modification incorporated into ONs significantly enhanced affinity to the complementary RNA. To evaluate the antisense potential of azetidine-T and aza-ENA-T modified ONs, they were subjected to RNase H promoted cleavage as well as tested towards nucleolytic degradation. Kinetic experiments showed that modified ONs recruit RNase H, however with lower enzyme efficiency due to decreased enzyme-substrate binding affinity, but with enhanced turnover number. Both, azetidine-T and aza-ENA-T modified ONs demonstrated improved 3'-exonuclease stability in the presence of snake venom phosphodiesterase and human serum compared to the unmodified sequence. Oligodeoxynucleotides (ODNs) containing pyrene-functionalized azetidine-T (Aze-pyr X) and aza-ENA-T (Aza-ENA-pyr Y) modifications showed different fluorescence properties. The X modified ODNs hybridized to the complementary DNA and RNA showed variable increase in the fluorescence intensity depending upon the nearest-neighbor at the 3'-end to X modification (dA > dG > dT > dC) with high fluorescence quantum yield. However, the Y modified ODNs showed a sensible enhancement of the fluorescence intensity only with complementary DNA. Also, the X modified ODN showed decrease (~37-fold) in the fluorescence intensity upon duplex formation with RNA containing a G nucleobase mismatch opposite to the modification site, whereas a ~3-fold increase was observed for the Y modified probe.
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Efeito do Yo Jyo Hen Shi Ko (YHK) no metabolismo lipídico na esteatohepatite experimental / Evaluation of Yo Jyo Hen Shi Ko (YHK) in hepatic lipid metabolism in experimental steatohepatitisIsabel Veloso Alves Pereira 19 May 2010 (has links)
A Doença Hepática Gordurosa Não Alcoólica (DHGNA) é atualmente uma das formas mais comuns de doença hepática, e está diretamente relacionada com a obesidade. Estudos indicam uma prevalência por volta de 30% na população ocidental e 11% na população oriental. A DGHNA possui um largo espectro abrangendo desde casos de esteatose simples sem inflamação, até casos com esteatohepatite e fibrose, podendo evoluir para cirrose e carcinoma hepatocelular. A fisiopatogênese da DHGNA é baseada em múltiplos eventos: resistência insulínica, aumento da lipólise periférica, aumento da síntese de novo de lipídeos, estresse oxidativo, endotoxemia crônica no desencadeamento da inflamação e fibrose entre outros. A etapa inicial caracteriza-se pelo acúmulo de ácidos graxos no hepatócito, suplantando sua capacidade de metabolização e exportação conseqüente à ação lipogênica da insulina, desta forma o metabolismo de ácidos graxos está intimamente ligado ao desenvolvimento da DHGNA. O Yo Jyo Hen Shi Ko (YHK) é um composto natural usado na medicina japonesa para tratamento de doenças hepáticas e apresenta propriedades antioxidantes, antiinflamatórias e hipolipemiantes. O presente estudo teve como objetivo avaliar o efeito do YHK no metabolismo hepático de lipídeos. Para tanto, foram utilizados camundongos obesos (ob/ob) com esteatohepatite não alcoólica (ENA) induzida por dieta deficiente em colina e metionina (DCM) e foram analisados no tecido hepático, genes relacionados com a síntese de novo de lipídeos (SREBP1c, FASn), genes relacionados com a oxidação e exportação de lipídeos (CPT1a e SCD-1, MTP), assim como genes relacionados com o armazenamento de lipídeos (Perilipina e ADFP). O YHK apresentou um efeito citoprotetor hepático com melhora dos parâmetros histológicos neste modelo experimental de ENA. Associadamente, houve redução na expressão de genes relacionados à síntese de novo como SREBP e da FASn, quando se comparou o grupo tratado com DCM+YHK com o grupo não tratado DCM. Em contrapartida, houve aumento na expressão da MTP e da SCD-1 ocasionando uma maior exportação de triglicerídeos hepáticos nos animais que utilizaram o YHK. Ainda, o YHK modulou as proteínas Perilipina e ADFP. Por outro lado, não houve modificação na oxidação de lipídeos.. Conclui-se que o YHK pode ser uma droga promissora no tratamento da DHGNA, já que age modulando genes envolvidos na síntese e exportação de lipídeos hepáticos, reduzindo o acúmulo de gordura no hepatócito / Nonalcoholic fatty liver disease (NAFLD) is currently one of the most common forms of liver disease, related directly to the increase of obesity in the world. Previous studies indicate a prevalence of around 30% in the western population and 11% in the eastern. This disease covers cases from simple steatosis without inflammation to cases of steato hepatitis (NASH) and fibrosis and it may lead to liver cirrhosis and hepatocellular carcinoma. The pathophysiology of NAFLD is based on multiple events: insulin resistance, increased peripheral lipolysis, increased de novo lipogenesis, oxidative stress, endotoxemia in triggering chronic inflammation and fibrosis and others. The initial stage of the disease is characterized by the accumulation of fatty acids in hepatocytes caused by the lipogenic action of insulin. This condition results in the surpassing of the cells ability to metabolize and export. This way, the metabolism of fatty acids is closely linked to the development of NAFLD. The Yo Jyo Hen Shi Ko (YHK) is a natural compound used in Japanese medicine for the treatment of liver disease and it has antioxidant, anti-inflammatory and lipid lowering properties. This study aimed to evaluate the effect of YHK in the hepatic metabolism of lipids. An experimental model was designed using obese mice (ob/ob) affected by NASH induced by a deficient diet in choline and methionine (MCD). Then, genes from its hepatic tissue related to de novo lipogenesis (SREBP1c, FASN), to lipid oxidation and exportation (CPT1A and SCD-1, MTP) as well as genes related to lipid storage (Perilipin and ADFP) were analyzed. The YHK presented a cytoprotective effect, improving the hepatic histological parameters in this experimental model. Additionally, when comparing the group treated with MCD + YHK (diet + YHK) to the untreated MCD group (diet) there was a reduction in the expression of genes related to de novo synthesis like SREBP1c and FASn. However, an increased expression of MTP and SCD-1 were observed leading to a greater liver exportation of fatty acids in animals that were treated with YHK. Moreover, the YHK modulated the proteins Perilipin and ADFP. On the other hand, there was no changing in lipid oxidation. In summary, the YHK can be a promising drug for the treatment of NAFLD, as it acts by modulating genes involved in the synthesis and exportation of hepatic lipids, reducing the accumulation of fat in hepatocytes
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Prototypování fotografické kompozice pomocí rozšířené reality / Prototyping of Photographic Composition Using Augmented RealityPalata, Petr January 2015 (has links)
The goal of this work was to create an application providing the user with an option of creating interesting and realistic looking montages in few easy steps using a mobile phone. The focus is on simplicity, user friendliness and the speed with which the final montage can be obtained. The work discusses available approaches to building such application, the algorithms needed and also the problems with the implementation of computer vision algo- rithms on a mobile device. It also discusses possible options for speeding up the algorithms through parallelization on newer devices running the iOS operating system.
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Ion and ENA precipitation onto the upper atmosphere of Venus : Estimate of precipitation maps using data from a hybrid model / Jon- och ENA-utfällning i den övre atmosfären av Venus : Uppskattning av nederbördskartor med hjälp av data från en hybridmodellObersnel, Lorenzo January 2023 (has links)
Venus does not have a strong intrinsic magnetic field as the Earth, and its magnetosphere is induced by the interaction of the solar wind with the ionosphere. The near-Venus space environment is characterized by the presence of a bow shock and of an induced magnetic boundary linked to the interplanetary magnetic field orientation. The interaction of the solar wind with the planetary atmosphere and exosphere is more direct than on Earth. This interaction energises ionospheric ions, leading to a loss of atmospheric compounds in space. Ions and energetic neutral atoms of solar wind or of planetary origin can precipitate onto the upper atmosphere of Venus, which is an important process of mass, momentum and energy transfer, and can lead to an increase of the loss of planetary constituents due to the atmospheric sputtering. The energetic neutral atoms are used as a diagnostic method, that gives a continuous and global imaging of the planetary magnetosphere. They are generated by multiple processes, as charge exchange, scattering and sputtering from the upper atmosphere of Venus. In this work, we study the precipitation of oxygen and hydrogen ions and energetic neutrals in the upper atmosphere of Venus. We use data produced with a global hybrid plasma model that simulated the interaction between Venus and the solar wind, and simulate the charge exchange process between the energetic ions and exospheric neutral particles to produce the energetic neutral atoms. Due to the low North-South asymmetry in the precipitation of oxygen planetary ions and energetic neutral atoms, we conclude that the effect of the finite gyroradius of oxygen ions is limited. Compared to the case of Mars, the fraction of the solar wind that precipitates as hydrogen energetic neutral atoms onto Venus is lower, consistently with the less extended exosphere of Venus. / Venus har inte ett starkt internt magnetfält som jorden, och dess magnetosfär induceras av solvindens växelverkan med jonosfären. Rymdmiljön nära Venus kännetecknas av närvaron av en bogchock och av en inducerad magnetisk gräns kopplad till den interplanetära magnetfältsorienteringen, genom en mer direkt växelverkan mellan solvinden och planetens exosfären och atmosfär än på jorden. Denna växelverkan aktiverar jonosfäriska joner, vilket leder till en förlust av atmosfär till rymden. Joner och energiska neutrala atomer i solvind eller av planetärt ursprung kankollidera med den övre atmosfären på Venus. Detta är en viktig typ av överföring av massa, rörelsemängd och energi och kan leda till en ökning av förlusten av planetära beståndsdelar på grund av sputtering. De energiska neutrala atomerna används som en diagnostisk metod, vilket ger en kontinuerlig och global avbildning av Venus magnetosfär. De är genererade av flera processer, som laddningsutbyte, spridning och sputtering från Venus övre atmosfär. I det här arbetet studerar vi precipitering av syre- och vätejoner och energiska neutraler i den övre atmosfären på Venus. Vi använder data som produceras med en global hybridplasmamodell som simulerar växelverkan mellan Venus och solvinden, och laddningsutbytesprocessen mellan de energiska jonerna och exosfäriska neutralpartiklar för att producera energiska neutrala atomer. På grund av den låga nord-sydliga asymmetrin i precipiteringen av planetära syrejoner och energiska neutrala atomer, drar vi slutsatsen att effekten av syrejonernas ändliga gyroradius är begränsad. Vi jämför precipitering väte och energiska neutralpartiklar på Venus med fallet på Mars. / A differenza della Terra, Venere non possiede un campo magnetico intrinseco. L’interazione del vento solare con la ionosfera del pianeta forma quella che è chiamata magnetosfera indotta. Questa struttura presenta un bow shock e un induced magnetic boundary (confine magnetico indotto) ed è fortemente legata all’orientamento del campo magnetico interplanetario. L’interazione tra il vento solare e l’atmosfera di Venere è più diretta in confronto a quanto accade per la Terra. Questa interazione è capace di energizzare ioni della ionosfera oltre alla loro velocità di fuga, portando a una perdita nello spazio di materiale di origine planetaria. Ioni o atomi neutri del vento solare o di origine planetaria possono precipitare nell’atmosfera del pianeta, trasferendo in questo modo energia, quantità di moto e massa dallo spazio a Venere. La precipitazione di ioni e atomi neutri può causare lo sputtering di materiale planetario e causare in questo modo un aumento della perdita di materia dall’atmosfera del pianeta. Gli atomi neutri energetici sono utilizzati come metodo di indagine per la magnetosfera, di cui possono fornire una rappresentazione globale e continua. Gli atomi neutri energetici sono generati da sputtering, backscattering e da processi di trasferimento di carica. In questa tesi è studiata la precipitazione nell’atmosfera di Venere di ioni e di atomi neutri, sia di idrogeno che di ossigeno. Sono utilizzati dati prodotti con un modello ibrido che simula l’interazione tra Venere e il vento solare. Gli atomi neutri energetici sono prodotti modellando il meccanismo di scambio di carica tra gli ioni e l’esosfera neutra di Venere. Si conclude che l’assimmetria calcolata nella precipitazione degli ioni di ossigeno è più bassa di quanto ci si sarebbe aspettato. La precipitazione di atomi neutri di idrogeno nell’atmosfera di Venere è confrontata con il caso di Marte.
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A molecular genetic analysis of the role of the Guanine Nucleotide Exchange Factor Trio during Axon Pathfinding in the Embryonic CNS of Drosophila melanogasterForsthoefel, David J. 10 October 2005 (has links)
No description available.
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