Ce travail experimental est consacre a l'etude de la multiplicite des electrons secondaires emis par des cibles minces de carbone bombardees par des protons, des atomes H0 et des ions moleculaires H2+ et H3+ d'energie variant de 0.25 a 2.2 MeV.<br /><br /> Le phenomene d'emission electronique secondaire par les surfaces des solides a l'impact de projectiles rapides resulte des interactions inelastiques des projectiles avec les electrons du solide. Une description phenomenologique te un rappel des differents modeles theoriques sont rassembles dans un premier chapitre.<br /><br /> Le second chapitre est consacre a la description du dispositif experimental utilise pour la mesure evenement par evenement du nombre d'electrons emis par les deux faces d'une cible mince de carbone lors du passage des projectiles incidents. Le traitement informatique des donnees experimentales, necessaire a la determination des distributions statistiques des electrons emis est egalement presente.<br /><br /> L'emission electronique induite par des atomes H0 a ete mesuree en correlation avec l'etat de charge des projectiles emergeant des cibles minces. Ces experiences, dont les resultats sont presentes dans le chapitre trois, nous ont permis de montrer le role particulier de l'electron d'un projectile selon qu'il reste ou non lie au projectile.<br /><br /> Le chapitre quatre est consacre a l'emission electronique induite par des ions polyatomiques H2+ et H3+. Les resultats sont intepretes en termes d'effets collectifs dans les interactions de tels ions avec les solides. le role de la proximite des protons, fragments des ions moleculaires, sur l'amplitude de ces effets collectifs est montre a partir des distributions statistiques des electrons secondaires emis par la face d'emergence des cibles.<br /><br /> Ces experiences ont permis de mettre en evidence des aspects particuliers des interactions d'atomes et d'ions polyatomiques avec les solides.

A subset of 199 Melissotarsus insularis and 130 Diaspididae specimens were analyzed to 1) determine the species status of M. insularis and 2) to explore the relative intimacy of the relationship between M. insularis and Diaspididae. An analysis of molecular variance and the observed lack of association between clades and distinct habitats on the M. insularis phylogeny suggested that while M. insularis exhibits isolation by distance, it does not apparently diversify by habitat. When cryptic COI pseudogenes were accounted for, the majority of the genetic diversity exhibited by M. insularis was limited to a divergence of 3% or less suggesting that M. insularis represents a single, albeit broadly distributed, species. A cophylogenetic reconstruction of the relationship between M. insularis and Diaspididae yielded 14 “cospeciation” events but was not significant unlike reconstructions of host-parasite relationships. Analyses of reduced datasets suggested that incomplete taxon sampling may significantly affect cophylogenetic reconstruction results. / National Science Foundation (grants No. DEB-0072713, DEB-0344731 to BLF and DEB-0842395 to BLF and MAS), a Natural Sciences and Engineering Research Council of Canada Discovery Grant to MAS and a Leaders Opportunity Fund grant from the Canada Foundation for Innovation to MAS

In this work are presented results of the experimental study of state selected reactions of H+ and N+(3PJa) ions with molecular hydrogen H2(J = 0, 1) at temperatures in the range 10 - 100 K using 22-pole rf ion trap apparatus. These reactions are important for the formation of interstellar trihydrogen cations and ammonia. To determine the temperature of ions, calibration measurements of the Doppler broadening of spectral lines using N2+ + Ar  Ar+ + N2 laser induced reaction and rate of the ternary association He+ + 2He  He2+ + He were performed. Both ternary and radiative channels of the H+ + H2(J) association reaction were observed at hydrogen number densities in the range 1012 - 1014 cm-3 and 1011 - 1012 cm-3 respectively. Obtained temperature dependences at 11 - 33 K demonstrate substantial role of the H2 rotational energy, results cannot be explained with the existed theories of the stabilization of collisional complexes. Measurements of the rate coefficient of N+(3PJa) + H2(J) reaction at different ortho fractions of H2 show dependence on internal energy of both reactants. State specific rate coefficients of the reaction of nitrogen and hydrogen ions were derived. The adiabatic model and collisional relaxations of N+(3PJa) fine structure levels were considered. Powered by TCPDF (www.tcpdf.org)

Made available in DSpace on 2016-06-02T20:19:21Z (GMT). No. of bitstreams: 1 5467.pdf: 2078884 bytes, checksum: ea4b65ac9862fb8231836d4cc2d57339 (MD5) Previous issue date: 2013-08-12 / Financiadora de Estudos e Projetos / Experimental studies indicate that the cerebellum works not only in motor control but performs more complex tasks, such as the consolidation of emotional memory. The purpose of this study was to evaluate the effects of actions of thioperamide (THIO), histaminergic H3 receptor antagonist, in the consolidation of emotional memory in mice through the cerebellar vermis. To this was done two experiments. Experiment 1 used the elevated plus maze (EPM) as the test apparatus, and the experiment 2 used the Inhibitory Avoidance Test (IAT). In both experiments were utilized four experimental groups of male mice of Swiss Albino strain, weighing between 25-35g. All animals were submitted to surgical procedure that consisted in the implementation of the guide cannula in the cerebellar vermis. In each experiment there was one control group that was treated with saline (SAL), and three groups that received pharmacological treatment of THIO different concentrations: 0.06, 0.3 and 1.5 ng/0.1&#956;l. The tests were done on two consecutive days (exposure and reexposure), and drug treatment occurred immediately after exposure. The data were analyzed using analysis of variance (ANOVA) of a track followed by the Duncan test (P <0.01). It was concluded that, in both experiments, the data of previous exposure groups pharmacological treatment did not differ significantly and were grouped in pool. In experiment 1 the reduction of exploration of the open arms on reexposure was considered indicative of learning and memory. The data of experiment 1 pointed out a deficit of emotional memory consolidation for the group with lower dose of THIO (0.06ng /0.1&#956;l), because the data of this group showed no statistical difference in relation to the pool for the variables %OAE and %TAE. The other groups (0.3 and 1.5 ng/0.1 &#956;l), had a reduction in exploratory activity. There was also a statistical difference between the groups of reexposure, being the smallest group of THIO, statistically different from SAL and the two groups of larger doses used in this study did not show this difference. None of the doses used THIO intervened in locomotor activity of the animals, because there was no difference in the variable EAE. In experiment 2 was indicative of learning and memory latency increase on reexposure. The latency increase was observed in groups SAL, 0.06 and 0.3ng/0,1 &#956;l compared with the pool. There was no difference for the group 1.5 ng/0.1 &#956;l. Among the group data of reexposure, there was a difference of 0.3 THIO groups and 1.5 ng/0.1 &#956;l compared to the control, and this difference was not observed in group THIO 0.06. / Trabalhos experimentais apontam que o cerebelo não atua somente no controle motor, mas realiza tarefas mais complexas, como a consolidação da memória emocional. O objetivo do presente estudo foi avaliar os efeitos da atuação da Tioperamida (TIO), antagonista do receptor histaminérgico H3, na consolidação da memória emocional de camundongos via vermis cerebelar. Para isso foi realizado dois experimentos. O experimento 1 utilizou o labirinto em cruz elevado (LCE) como aparato de teste, e o experimento 2 a esquiva inibitória (EI). Em ambos os experimentos foram utilizados 4 grupos experimentais de camundongos machos, da cepa Suiço Albino, pesando entre 25-35 g. Todos os animais foram submetidos ao procedimento cirúrgico que consistiu na implantação da cânula guia no vermis cerebelar. Em cada experimento havia um grupo controle, que foi tratado com salina (SAL), e três grupos que receberam tratamento farmacológico de diferentes concentrações de TIO: 0,06, 0,3 e 1,5 ng/0,1&#956;l. Os testes foram realizados em dois dias consecutivos (exposição e reexposição), sendo que o tratamento farmacológico ocorreu imediatamente após a exposição. Os dados foram analisados utilizando-se a análise de variância (ANOVA) de uma via, seguida do teste de Duncan (p<0,01). Foi constatado que, em ambos os experimentos, os dados dos grupos da exposição anteriores ao tratamento farmacológico não apresentaram diferença estatística e foram agrupados em pool. No experimento 1 a diminuição da exploração dos braços abertos na reexposição foi considerada indicativo de aprendizado e memória. Os dados do experimento 1 apontaram déficit da consolidação da memória emocional para o grupo de menor dose de TIO (0,06 ng/0,1&#956;l), pois os dados deste grupo não apresentaram diferença estatística em relação ao pool, para as variáveis porcentagem de entrada em braços abertos (%EBA) e porcentagem de tempo gasto nos braços abertos ( %TBA). Os demais grupos (0,3 e 1,5 ng/0,1&#956;l) apresentaram redução da atividade exploratória. Houve também diferença estatística entre os grupos da reexposição, sendo o menor grupo de TIO estatisticamente diferente do SAL e os dois grupos de maiores doses utilizados neste estudo, não apresentaram esta diferença. Nenhuma das doses de TIO utilizadas interferiram na atividade locomotora dos animais, pois não houve diferença na variável EBF. No experimento 2 foi indicativo de aprendizagem e memória o aumento da latência na reexposição. O aumento da latência foi observado nos grupos SAL, 0,06 e 0,3 ng/0,1&#956;l em comparação com o pool, e não houve diferença para o grupo 1,5 ng/0,1&#956;l. Entre os dados dos grupos da reexposição, houve diferença dos grupos TIO 0,3 e 1,5 ng/0,1&#956;l em comparação ao controle, e não foi observada esta diferença em relação ao grupo TIO 0,06. Os resultados do experimento 2 indicam facilitação da consolidação da memória emocional para o grupo de dose intermediária de TIO (0,3 ng/0,1&#956;l) e prejuízo para a maior dose de TIO (1,5 ng/0,1&#956;l).

Eukaryotic genomes can produce two types of transcripts: protein-coding and non-coding RNAs (ncRNAs). Cryptic ncRNA transcripts are bona fide RNA Pol II products that originate from bidirectional promoters, yet they are degraded by the RNA exosome. Such pervasive transcription is prevalent across eukaryotes, yet its regulation and function is poorly understood. We hypothesized that chromatin architecture at cryptic promoters may regulate ncRNA transcription. Nucleosomes that flank promoters are highly enriched in two histone marks: H3-K56Ac and the variant H2A.Z, which make nucleosomes highly dynamic. These histone modifications are present at a majority of promoters and their stereotypic pattern is conserved from yeast to mammals, suggesting their evolutionary importance. Although required for inducing a handful of genes, their contribution to steady-state transcription has remained elusive. In this work, we set out to understand if dynamic nucleosomes regulate cryptic transcription and how this is coordinated with the RNA exosome. Remarkably, we find that H3-K56Ac promotes RNA polymerase II occupancy at a large number of protein coding and noncoding loci, yet neither histone mark has a significant impact on steady state mRNA levels in budding yeast. Instead, broad effects of H3-K56Ac or H2A.Z on levels of both coding and ncRNAs are only revealed in the absence of the nuclear RNA exosome. We show that H2A.Z functions with H3-K56Ac in chromosome folding, facilitating formation of Chromosomal Interaction Domains (CIDs). Our study suggests that H2A.Z and H3-K56Ac work in concert with the RNA exosome to control mRNA and ncRNA levels, perhaps in part by regulating higher order chromatin structures. Together, these chromatin factors achieve a balance of RNA exosome activity (yin; negative) and Pol II (yang; positive) to maintain transcriptional homeostasis.

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