The thesis entitled “Intermolecular Interactions in Molecular Crystals: Quantitative Estimates from Experimental and Theoretical Charge Densities” consists of four chapters and an Appendix. Chapter 1 highlights the principles of crystal engineering from charge density point of view. Chapter 2 (Section I - III) deals with the evaluation of weak intermolecular interactions and in particular related to the features of concomitant polymorphism. Chapter 3 describes the co-operative role of weak interactions in the presence of strong hydrogen bonds in small bioactive molecules in terms of topological properties. Chapter 4 unravels the inter-ion interactions in terms of charge density features in an ionic salt. The general conclusions of the works presented in this thesis are provided at the end of the chapters. Appendix A explores the varieties of hydrogen bonds in a simple molecule. Identification of intermolecular interactions based purely on distance-angle criteria is inadequate and in the context of ‘quantitative crystal engineering’, recognition of critical points in terms of charge density distribution becomes extremely relevant to justify the occurrence of any interaction in the intermolecular space. The results from single crystal X-ray diffraction data at 90K (compound in chapter 4 at 113K) have been compared with those from periodic theoretical calculations via DFT method at high-level basis set (B3LYP/6-31G**) in order to establish a common platform between theory and experiment. Chapter 1 gives a brief review on crystal engineering to analyze intermolecular interactions along with the description of both experimental and theoretical approaches used in the analysis of charge densities in molecular crystals. The eight of Koch and Popelier’s criteria, defined using the theory of “Atoms in Molecules”, to characterize hydrogen bonds have also been discussed in detail. Chapter 2 (I) presents the charge density analysis in coumarin, 1-thiocoumarin, and 3-acetylcoumarin. Coumarin has been extensively studied as it finds applications in several areas of synthetic chemistry, medicinal chemistry, and photochemistry. The packing of molecules in the crystal lattice is governed by weak C−HLO and C−HLπ interactions only. The variations in charge density properties and derived local energy densities have been investigated in these regions of intermolecular interactions. The lacuna of the identification of a lower limit for the hydrogen bond formation has been addressed in terms of all eight of Koch and Popelier’s criteria, to bring out the distinguishing features between a hydrogen bond (C−HLO) and a van der Waals interaction (C−HLπ) for the first time. Chapter 2 (II) highlights the nature of intermolecular interactions involving sulfur in 1-thiocoumarin, 2-thiocoumarin, and dithiocoumarin. These compounds pack in the crystal lattice mainly via weak C−HLS and SLS interactions. The analysis of experimental and theoretical charge densities clearly categorizes these interactions as pure van der Waals in nature. The distribution of charge densities in the vicinity of the S atom has been analyzed to get better insights into the nature of sulfur in different environments. Chapter 2 (III) provides a detailed investigation of the charge density distribution in concomitant polymorphs of 3-acetylcoumarin. The electron density maps in the two forms demonstrate the differences in the nature of the charge density distribution particularly in the features associated with C−HLO and C−HLπ interactions. The net charges derived based on the population analysis via multipole refinement and also the charges evaluated via integration over the atomic basins and the molecular dipole moments show significant differences. The lattice energies calculated from experimental charge density approach clearly suggest that form A is thermodynamically stable compared to form B. Mapping of electrostatic potential over the molecular surfaces also bring out the differences between the two forms. Chapter 3 describes the analysis of charge density distribution in three small bioactive molecules, 2-thiouracil, cytosine monohydrate, and salicylic acid. These molecules pack in the crystal lattice via strong hydrogen bonds, such as N−HLO, N−HLS, and O−HLO. In spite of the presence of such strong hydrogen bonds, the weak interactions like C−HLO and C−HLS also contribute in tandem to the packing features. The distribution of charge densities in intermolecular space provides a quantitative comparison on the strength of both strong and weak interactions. The variations in electronegativity associated with the S, O, and N atoms are clearly seen in the electrostatic potential maps over the molecular surfaces. Chapter 4 deals with study of intermolecular interactions in N,N,N´N´-tetramethylethlenediammonium dithiocyanate, analyzed based on experimental charge densities from X-ray diffraction data at 113 K and compared with theoretical charge densities. The packing in the crystal lattice is governed mainly by a strong N+−H…N− hydrogen bond along with several weak interactions such as C−HLS, C−HLN, and C−HLπ. The charge density distribution in the region of inter-ionic interaction is also highlighted and the electrostatic potential map clearly provides the insights in to its interacting feature. Appendix A describes the experimental and theoretical charge density studies in 1-formyl-3-thiosemicarbazide and the assessment of five varieties of hydrogen bonds.

As modificações ambientais provocadas pela humanidade, em especial pela agricultura, têm sido motivo de preocupação e estudos por todo o mundo. Nesse sentido, os solos figuram como um dos compartimentos ambientais mais impactados pelo uso de agrotóxicos, produtos amplamente utilizados na agricultura moderna. O objetivo deste trabalho foi avaliar se e como os agrotóxicos Score® 250 EC (i.a. difenoconazol) e Kraft® 36 EC (i.a. abamectina), isolados e em mistura, afetam a flora (germinação e crescimento do tomate - Lycopersicon lycopersicum), as comunidades microbianas do solo (biomassa microbiana em carbono, respiração, quociente metabólico e enzima β-glucosidase) e os enquitreídeos (reprodução de Enchytraeus crypticus em diferentes densidades e a relação trófica entre estes e os microrganismos), ao longo do tempo após a contaminação do solo. Em relação aos parâmetros microbianos, a despeito de algumas variações em decorrência da presença dos agrotóxicos, os indicadores das funções gerais do sistema edáfico não foram grandemente prejudicados, expressando uma redundância funcional. Não obstante, o solo-controle apresentou maior estabilidade em relação às variações dos parâmetros, sugerindo que os microrganismos presentes neste solo apresentaram uma maior robustez e estabilidade ao longo do tempo. Em relação aos testes com E. crypticus, os índices de reprodução não foram significativamente alterados em função da ação dos agrotóxicos, mas ratificou-se a importância dos microrganismos na dieta dos mesmos, haja vista as correlações entre o tamanho das comunidades microbianas e as taxas de crescimento dos enquitreídeos. Com relação ao crescimento e germinação do tomate, puderam ser observados valores maiores de altura e massa seca das plântulas em relação ao controle. Em contrapartida, observou-se uma possível melhor tendência de crescimento das plântulas no solo controle ao longo do tempo. Por fim, considerando a complexa problemática brasileira em relação ao uso de agrotóxicos, reiterou-se a importância do cumprimento das recomendações de aplicação de ambos os agrotóxicos avaliados por parte dos agricultores e recomendou-se a iniciativa de diminuição progressiva da sua utilização. / Environmental changes caused by humanity, especially by agriculture, have been a cause for concern throughout the world. The soils are one of the environmental compartments most impacted by the use of pesticides, which are widely used in modern agriculture. This research aimed at evaluating whether and how the insecticide Kraft® 36 EC (a.i. abamectin) and the fungicide Score® 250 EC (a.i. difenoconazole), isolated and in mixture, affect: a) the soil microbial communities (microbial biomass carbon, respiration, metabolic quotient and β-glucosidase enzyme); b) enchytraeid worms (reproduction of Enchytraeus crypticus in different densities and their trophic relation with microorganisms); and c) the flora (emergence and growth of tomato - Lycopersicon lycopersicum), over 84 days after contamination. The microbial indicators were not greatly impaired and expressed a functional redundancy, despite some variations due to the presence of pesticides. Nevertheless, the control group presented a greater stability than the contaminated ones, suggesting a greater robustness and stability of microorganisms over time, which are important factors for a better quality of the soil. In relation to E. crypticus tests, the importance of microorganisms on their diet was ratified, since positive correlations between the size of microbial communities and the enchytraeids rate of increase were observed. The different densities of E. crypticus were not significantly influenced by the effects of pesticides on the microorganisms. With respect to the growth and germination of tomato, higher values of height and dry mass of the seedlings were observed in contaminated groups. On the other hand, a higher growth tendency of the seedlings in the control soil was observed over time. Finally, considering the complexity of the Brazilian pesticide issue, we emphasize the importance of compliance of the recommendations on pesticides application and reinforce the initiative of decreasing their use.

<p> Populations of three tubicolous polychaetes, Clymenella torquata, Spiophanes wisleyi and Sabellaria vulgaris located in the intertidal zone of the south shore of Cobequid Bay, Nova Scotia were studied for their effects on the surrounding sediment. Grain size measurements were made of the tubes and the surrounding sediment. T-tests were made on the resultant differences between the Inman sorting and mean statistics of the two sand populat ions . The percentages of heavy and light minerals were also measured with the use of a binocular microscope. The differences in sorting and mean grain size between the tubes and substrate may affect stability and porosity of the sediment and effect sediment structures easily identifiable in the geologic record. </p> <p> Clyrnenella torquata inhabits a low energy intertidal sandy envir onment and increases the porosity of the sediment by its feeding habits. Stabilization of the sediment may be effected by high population densities of Clymenella (densities around 420/m^2). Tubes were built with preferential grain sizes. Spiophanes wisleyi exists in phenomenally high population densities in low-energy areas. The large numbers of tubes (up to 98,000/m^2) bind the sediment; tubes are made of virtually the same grain sizes as the substrate; no bioturbation occurs during the construction of the tubes. The latter two factors make preservation potential very low in the geologic record. Sabellaria vulgaris in the study area is of little sedimentological importance. Population densities are too low to affect the surrounding substrate. This species exists in a high energy zone a characteristic of fauna which build reefs. Reef formation by sabellariids may have been important in the geologic past and is locally important today in the North Sea (Schafer, 1972) and Florida (Gram, 1968). </p> / Thesis / Bachelor of Science (BSc)

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Les progrès dans le domaine de la neuroimagerie cérébrale ont permis une certaine compréhension des maladies mentales comme la schizophrénie. Cependant, peu de résultats sont cohérents et ils sont souvent contradictoires, ce qui rend difficile de tirer des conclusions concrètes par rapport à la maladie. Plusieurs facteurs jouent un rôle dans les résultats divergents et convergents : Les différentes techniques d'imagerie et les analyses, le nombre de patients inclus dans les études, l'âge des patients, l'âge de l’'apparition de la maladie, les critères de diagnostic, les effets du traitement antipsychotique, le statut social, ainsi que les comorbidités, font partie de ces facteurs. Bien que les différences cérébrales entre femmes et hommes « normaux » sont bien établies, ce n’est que ces dernières années que des études en neuroimagerie de la schizophrénie ont abordé les différences homme-femme comme une explication potentielle des résultats discordants de l’imagerie cérébrale. L'objectif de cette thèse est de comprendre le rôle du sexe (genre féminin et masculin) dans les anomalies anatomiques observées dans la schizophrénie; ceci, en réalisant des études qui contrôlent, autant que possible, l'effet de différentes variables confondantes et en utilisant des analyses d’IRM automatisées chez des patients et des sujets sains de même âge et du même sexe. Une brève revue globale des résultats actuels dans le domaine de la schizophrénie ainsi que des résultats liés aux différences entre les sexes dans la schizophrénie vont être présentés. La première étude visait à étudier l'influence des différences de sexe sur des mesures de la gyrification corticale de la schizophrénie. Étant donné que la schizophrénie est une maladie dont les «symptômes cliniques » ont un impact négatif sur la qualité de vie des patients qui en souffrent, nous avons exploré la relation entre la gyrification corticale et les différents symptômes de la schizophrénie chez les hommes et les femmes atteints de ce trouble psychiatrique. Le rôle du sexe sur la gyrification corticale et son association aux symptômes a été à peine étudié chez les patients atteints de schizophrénie ; c’est pour cette raison que, nous croyons que cette étude est d’une importante valeur. Dans cette première étude, des images 3T T1 ont été acquises auprès de 48 patients atteints de schizophrénie (24 hommes [SZ-M] et 24 femmes [SZ-F]) et 48 volontaires sains (24 hommes [NC-M] et 24 femmes [NC-F]), appariés en fonction de l'âge et du sexe. Des mesures d’indice de gyrification (IG) pour chaque hémisphère et les quatre lobes cérébraux (frontaux, temporal, pariétal, et occipital) ont été effectuées en utilisant le pipeline de CIVET, lequel est entièrement automatisé. Plusieurs résultats intéressants ont émergé: les patients avaient des valeurs inférieures importantes de l’IG global par rapport aux témoins; SZ-M avaient des valeurs d'IG hémisphériques significativement inférieurs par rapport à NC-M, cela n'a pas été observé dans les groupes de femmes. Aucune différence entre les sexes dans les valeurs de diminution de l’IG avec l'âge n’a été observés chez les témoins sains par contre, une diminution de la valeur de l’IG avec l’âge chez les patients était plus importante chez les patients homme que les patients femmes. Une détérioration plus progressive dans l'hémisphère droit dans les deux groupes de patients a été observée, tout comme des réductions significatives des valeurs d’IG en relation avec la durée de la maladie chez SZ-M, mais pas chez SZ-F. Dans les groupes de patients, on observe des diminutions des valeurs d’IG dans les lobes frontaux bilatéraux et, le lobe occipital droit; le groupe SZ-M a montré une valeur d’IG significativement plus élevée par rapport à NC-M dans le lobe temporal droit; SZ-F a montré des valeurs d’IG significativement plus faibles dans les lobes bilatéraux frontaux, temporaux, pariétaux et le lobe occipital droit, par rapport à NC-F. Aucune corrélation significative n'a été trouvée entre les valeurs de l'IG et le profil de la symptomatologique dans les deux groupes de patients. Etant donné que l’IG reflète, en partie, des altérations dans le développement et la connectivité cérébrale, la diminution de l’IG observée chez les patients est en accord avec le modèle de développement neurobiologique de disconnectivité dans la schizophrénie. De plus, nous soulignons l'importance de l'âge ainsi que la durée de la maladie lorsque nous comparons les hommes et les femmes atteints de schizophrénie. Cependant, nous n'avons pas observé de corrélation significative n'a été trouvée entre les valeurs de l'IG et les symptômes, ce qui est d'un intérêt particulier et inattendu compte tenu des résultats de la neuroimagerie montrant par exemple certaines corrélations entre les symptômes positifs et certaines anomalies du lobe temporal dans la schizophrénie. Considérant ces résultats, nous avons décidé d'investiguer, dans notre deuxième étude, l'association entre les symptômes et les densités de matière grise (DMG) et de matière blanche (DMB) à la place des mesures de gyrification corticale. Nous avons utilisé la morphométrie basée sur le voxel "Voxel Based Morphometry (VBM8.0 with Diffeomorphic Anatomical Registration (Through Exponentiated Lie Algebra [DARTEL])" et la modélisation linéaire automatique (SPSS21.0 ALM) sur les images 3T T1 MPRAGE acquises auprès de 40 patients atteints de schizophrénie (SZ) et 41 témoins sains (NC). Nous avons trouvé que les patients atteints de schizophrénie avaient une DMG réduite dans le cortex cingulaire antérieur, le cortex temporal médian gauche et une DMG plus élevée dans le cortex cingulaire postérieur gauche par rapport aux sujets sains. Une diminution significative de DMB dans la région fronto-rectal inférieure gauche et la région pariétale postérieure gauche a été observée chez les patients comparés aux sujets sains. Nous avons trouvé des corrélations positives entre les symptômes positifs et la DMG dans l'insula gauche et le noyau caudé droit; et entre les symptômes négatifs et la DMG dans le cortex frontal médian droite et le lobe postérieur de cervelet droit. Nous avons aussi trouvé des corrélations négatives de DMG dans la région pariétale droite (précuneus), le lobe postérieur du cervelet gauche et les symptômes positifs; ainsi qu'entre la DMG du lobe antérieur du cervelet gauche et les symptômes négatifs. En outre, des corrélations positives ont été trouvées entre la DMB dans le cortex frontal médian droit et les symptômes positifs et entre le DMB dans la région frontale supérieure droite et les symptômes négatifs. Des corrélations négatives ont été trouvées entre les symptômes positifs et la DMB dans la région occipitale inférieure droite et le cunéus occipital droit, tandis que des corrélations négatives ont été trouvées entre la DMB et la région frontale supérieure gauche. Il est intéressant de noter que lorsque les symptômes ont été analysés par regroupement, nous avons trouvé que le symptôme de la désorganisation conceptuelle corrélait positivement avec la DMG totale et la DMB totale. L’augmentation de DMG a été associée à une diminution de la gravité des hallucinations et du manque de spontanéité; tandis que l'augmentation de DMB totale a été associée à la diminution de la sévérité de l'hostilité et des idées de grandeur. Une comparaison entre les groupes d'hommes a montré une diminution de la DMG chez les patients schizophrènes, tandis qu’aucune différences n’a été observée dans les groupes de femmes. Nous n’avons trouvé aucune corrélation entre la DMG, la DMB, le liquide cérébro-spinal, le volume total du cerveau, les symptômes individuels et la schizophrénie chez les sujets féminins. Chez les hommes atteints de schizophrénie, on observe des corrélations négatives importantes entre les idées de grandeur et la DMB; des corrélations positives entre la désorientation et la DMB. De plus on observe des corrélations entre et les déficits d'attention et de DMG et DMB. Nos résultats montrent que ces associations sont différentes chez les hommes et les femmes atteints de la schizophrénie. La symptomatologie de schizophrénie est un mélange de déficits cognitifs et socio-affectifs. Dans ce contexte, le but de notre troisième étude est d'étudier chez les patients atteints de la schizophrénie des DMG et DMB et leur relation avec l’acuité mnésique avec des contenus émotionnelles (négatives, positives et neutres) ainsi que étudier l'effet des différences de sexe sur nos résultats. Quarante et un patients droitiers, traités par antipsychotique, souffrant de schizophrénie (SZ) et 40 témoins sains (NC), tous droitiers, ont participé à l’étude. Nous avons utilisé des images de l'International Affective Picture System (IAPS), une banque d'images émotionnelles, et de l’IRM. On observe chez les témoins sains des corrélations entre les valeurs élevées de DMG du cortex pariétal postérieur, du lentiform, du putamen, noyau caudé, le cortex orbitofrontal inférieur gauche et la reconnaissance des images négatives. On observe des corrélations entre la DMG dans la région temporale gauche, fusiforme et la reconnaissance des images positives ; et également dans le cervelet antérieur gauche et l’acuité des images neutres. Chez les patients on observe des valeurs élevées des DMG dans le cortex occipital inférieur gauche et la reconnaissance des images négatives, mais aucune corrélation entre la capacité de reconnaissance des images positives ou neutres. Nous avons observé chez les témoins sains: des relations significatives entre la DMB dans le cortex pariétal postcentral gauche et la capacité de reconnaître des images négatives; dans le cortex temporal inferieur gauche, le cortex pariétal gauche (précuneus), le cortex frontal gauche et la capacité de reconnaissance des images positives; des valeurs de DMB du cortex temporel médian et l’acuité des images neutres. Les patients atteints de schizophrénie ont montré des relations significatives entre de DMB dans le cortex occipito-lingual gauche et la reconnaissance des images négatives ; dans le cortex pariétal angulaire gauche et la reconnaissance des images positives ; et dans le cortex temporal supérieur droit et les images neutres. Les différences de sexe dans la schizophrénie ont été observées : chez les patients de sexe masculin, des corrélations négatives ont été trouvées entre les DMB et la capacité de reconnaître des images négatives et positives. Chez les hommes sains, nous avons trouvé des corrélations positives entre des valeurs totales de DMG et la capacité de reconnaître des images négatives. Nous n’avons pas observé de corrélations dans les groupes de femmes. Ces résultats soutiennent l'hypothèse de l'atrophie fronto-temporale régionale chez les patients schizophrènes. Toutefois, nous notons qu’ils ont des augmentations relatives des valeurs de DMB dans le cortex occipito-pariétal. Nous avançons l'hypothèse que les déficits mnésiques chez les patients sont liés à des perturbations dans la coordination des réseaux cérébraux, ce qui peut être affecté par des déficits structuraux plus évidents chez les patients masculins. Par conséquent, nous préconisons que les futures études devraient utiliser le connectome ou l’approche « réseaux cérébraux » pour étudier l’impact du sexe (genre masculin-féminin) sur les déficits cognitifs et symptomatologiques dans la schizophrénie. Nos résultats globaux soulignent l'importance de la différence entre homme et femme dans la modulation de manifestations cliniques et fonctionnelles de la schizophrénie. Ainsi, nous croyons que le contrôle des covariables comme l'âge, la durée de la maladie et le statut social est insuffisant et que les études futures sur la schizophrénie devraient systématiquement séparer les hommes des femmes, afin de mieux comprendre cette maladie mentale complexe et dévastatrice. / Advances in cerebral neuroimaging techniques have helped our understanding of mental illnesses, such as schizophrenia. Few findings remain consistent and are often contradictory, making it difficult to draw informative conclusions about the disease. Several factors play a role in both diverging and converging results. Imaging technique and analyses, number of patients involved, age of patients, age at onset of the disease, diagnostic criteria, antipsychotic treatment effects, social status, comorbidities, are among some of the reasons. Despite well established cerebral sex differences in healthy population, it is only in recent years that neuroimaging studies in schizophrenia have addressed sex differences as a major possible explanation for discrepant neuroimaging finding. The aim of this thesis is to help understand the role of sex on brain structures in schizophrenia, by conducting studies that control as much as possible for other variables and by using MRI automated analyses for patients and controls matched for age and sex. This work will briefly present findings in schizophrenia in general, and then an extensive review of the literature on sex differences in schizophrenia will be presented. From it, we are able to conclude that sex differences have been reported with rare exception in almost all aspects involved in the life of patients with schizophrenia. Chapters 1. The first study investigated sex differences in cortical gyrification in schizophrenia patients (SZ). In addition, considering that schizophrenia is a disease of “clinical symptoms” that determine the quality of life of patients afflicted by it, we explored the relation between cortical gyrification and symptoms in males and females with schizophrenia. The role of sex on cortical gyrification and its association with symptoms has been scarcely investigated in patients with schizophrenia. In this study, 3T T1 images were acquired from 48 schizophrenia patients (24 males [SZ-M] and 24 females [SZ-F]) and 48 normal controls [NC] (24 males [NC-M] and 24 females [NC-F]) matched for age, sex, and handedness. Gyrification Index (GI) analyses for each hemisphere and four cerebral regions (frontal, temporal, parietal, and occipital) were performed using the fully automated CIVET pipeline. Patients had significant lower values of the overall GI relative to normal controls and SZ-M had significant lower right hemispheric GI values compared to NC-M. This was not observed in either NC-F or in SZ. No gender difference in GI values decreases with age were observed in NC. In patients, GI decreases with age were greater in SZ-M than SZ-F, with a more progressive deterioration in the right hemisphere in both patient groups. Significant GI value reductions in association with duration of illness were observed in SZ-M but not in SZ-F. Patient groups had lower GI in bilateral frontal, temporal, and parietal lobes than controls. SZ-F had significant lower GI values in left frontal, bilateral temporal and left parietal lobe compared to NC-F. No significant correlations were found between GI values and symptom scores in either group of patients. Since GI reflects, in part, alterations in cerebral development and connectivity, the decrease in GI observed in patients is in agreement with the neurodevelopmental model of disconnectivity in schizophrenia, and may explain the worse prognosis and social outcome observed in male patients. Furthermore, we emphasize the importance of age and duration of illness when comparing males and females with schizophrenia. Observed differences between male and female patients may reflect a more diffuse and generalized cortical loss in males. Female patients had cortical loss in specific regions, while preserving cortical gyrification in compensatory regions. Our latter finding -no significant correlation between GI values and symptom scores- was of particular interest and was unexpected in view of neuroimaging findings of correlations between positive symptoms and temporal lobe abnormalities. 2. In the second study, we examined the association between symptoms and brain structure using gray (GMD) and white matter (WMD) densities. Voxel-based morphometry (VBM8.0 with Diffeomorphic Anatomical Registration Through Exponentiated Lie Algebra [DARTEL]) and Automatic Linear Modeling (SPSS21.0 ALM) were used on 3T T1 MPRAGE images acquired from 40 schizophrenia patients (SZ) and 41 normal controls (NC). We found that SZ had lower GMD in the anterior cingulate cortex and left middle temporal gyrus, and higher GMD in the left posterior cingulate in comparison to NC. SZ had significantly lower WMD in the left inferior fronto-rectal and the left posterior parietal regions in comparison to NC. Significant positive correlations were found between positive symptoms and GMD in the left insula and right caudate, and between negative symptoms and GMD in the right middle frontal and the posterior lobe of the right cerebellum (uvula). Inverse relationships between GMD in the right parietal (precuneus), the left posterior lobe of the cerebellum (uvula) and positive symptoms, and between GMD in the left anterior lobe of the cerebellum and negative symptoms were observed in SZ. In addition, positive correlations were found between WMD in the right middle frontal lobe, and between positive symptoms and WMD in the right superior frontal region with negative symptoms. Negative correlations were found between positive symptoms and WMD in the right inferior occipital and the right occipital cuneus, while negative symptoms correlated negatively with the WMD of the left superior frontal. When symptom clusters were analyzed, conceptual disorganization symptom positively correlated with both total GMD and WMD. While increases in GMD were associated with decreased severity of lack of spontaneity and hallucinations symptom, increases in total WMD were associated with decreased severity of hostility and grandiosity symptoms. Comparison between male subjects revealed decreased GMD in male schizophrenia patients, while no differences were observed between females across groups. No correlations were found in female groups between GMD, WMD, CSF, or total brain volume and individual symptoms. In males with schizophrenia, significant negative correlation between ideas of grandiosity and WMD, a positive correlation between disorientation and WMD, and attention deficits and GMD and WMD were found. The current data suggest region-specific GMD and WMD association with negative and positive symptoms. In addition, it reveals that such associations are different in male and female schizophrenia patients. 3. The third study investigated the relationships of GMD and WMD with memory accuracy for emotionally negative, positive, and neutral pictures in schizophrenia patients relative to normal controls. Schizophrenia is characterized by an amalgam of cognitivo-socio-emotional deficits. The relationship between emotion processing on cognition and neurobiological underpinnings merit more attention than it has received so far. Memory deficits are among the most common deficits in schizophrenia and have a widespread impact on cognition in general. Additionally, consistently with the major theme of the present thesis, we investigated the effect of gender on the observed effect. Forty one, right-handed medicated patients with schizophrenia (SZ) and 40 right-handed normal controls (NC) matched by age and sex were assessed for memory accuracy using negative, positive and neutral pictures taken from the International Affective Picture System (IAPS). Imaging methods and analyses were similar to our second study. Fifteen minutes after presentation of selected IAPS images (incidental encoding), subjects were asked to recognize the previously seen images among other images. We found higher GMD in NC in the right posterior parietal cortex, lentiform, putamen, and caudate, as well as the left inferior orbitofrontal cortex, in relation with the negative images accuracy. NC had higher GMD in the left temporal and fusiform regions in relation with the positive images accuracy, and higher GMD in the left anterior cerebellum in relation with neutral images. Schizophrenia subjects had higher GMD in the left inferior occipital cortex in relation with the negative images accuracy, but GMD was not correlated with positive or neutral images accuracy in this group. WMDs correlations were higher in NC in the left postcentral parietal region for negative images; in the left inferior temporal, left precuneus parietal, and left frontal regions for positive images; and in the left middle temporal region for neutral images. Schizophrenia patients had higher WMD in the left lingual occipital for negative images; in the left angular parietal for positive images; and in the right superior temporal region for neutral images. While examining the two sexes separately, we observed inverse correlations between WMD and both negative and positive pictures in male patients. In addition, only in male controls, GMD positively correlated with negative pictures and this correlation was absent in female SZ subjects and NC females. These findings support the hypothesis of fronto-temporal regional atrophy in schizophrenia. Schizophrenia patients have relatively increased occipito-parietal WMD, advancing the hypothesis that the core pathophysiological problem underlying recall memory in SZ may be related to disruptive alterations in the coordination of large-scale brain networks, and this may be affected by structural deficits that are more evident in male patients. It is recommended that future studies should use the connectomes or the brain networks approach to investigate the effect of sex on memory deficits in schizophrenia. Our overall findings point out to the importance of sex in modulating the clinical and functional manifestations of schizophrenia. We believe that controlling for covariates as age, duration of illness, social status, etc. is insufficient and that future studies in schizophrenia should systematically separate male and female findings, if we wish to understand this complex and devastating mental illness.

A formação de camadas de cargas elétricas na superfície de Hélio liquido e em filmes de H´leio sobre um substrato está bem estabelecida tanto teórica quanto experimentalmente. Não existia, porém, até o presente, um cálculo auto-consistente para essas camadas de cargas, pois no regime de baixas densidades eletrônicas, estes sistemas podem ser tratados como o problema de 1-elétron. Em nosso trabalho incluímos os efeitos de muitos corpos usando a aproximação de Hartree-Fock e, via cálculos auto-consistentes, mostramos que estes efeitos tornam-se relevantes para densidades a partir de 108 e/cm2 para elétrons sobre Hélio e 103 e/ cm2 para elétrons sobre filme de Hélio. Calculamos também a mobilidade desses elétrons, em superfície de Hélio, incluindo dois mecanismos diferentes de espalhamento; as interações elétron-ripplons e elétrons-átomos de vapor. Usando nossos cálculos auto-consistentes obtivemos resultados que melhores concordam com dados experimentais para a mobilidade, em regimes de altas densidades eletrônicas / The formation of electric charged layers outside liquid Helium and outside films are well understood experimentally as well as theoretically. But, until today, there was not a self-consistent calculation for these electronic layers because, at low densities, these system can be treated as a one-electron problem. In this work we have included the many-body effects using the Hartree-Fock approximations and, via self-consistent calculations, we pointed out that these effects are relevants for densities above 108 e/cm2 for liquid Helium and 103 e/ cm2 for Helium films. We also have calculated the electronic mobility due to different scattering mechanisms: electron-ripplon and electron-vapour interactions. Using our self-consistents calculations we have obtained results that fit very well the experimental data, at high densities

O presente trabalho foi desenvolvido na área experimental da ESALQ-USP, localizada no município de Piracicaba/SP, em um Latossolo Vermelho Amarelo, textura areno-argiloso. O experimento teve como objetivo estudar a dinâmica do N no sistema solo-planta da cultura do milho, sob implantação do sistema plantio direto, e, pela técnica do 15N, avaliar a lixiviação de nitrato à profundidade de 0,80 m, a eficiência de utilização do N e o efeito residual do fertilizante nas culturas subseqüentes. O projeto envolveu dois cultivos de milho e um de aveia preta, cultivada na entressafra. O delineamento experimental foi o de blocos casualizados (3x2), com 4 repetições. Os tratamentos consistiram de doses de nitrogênio, na forma de sulfato de amônio (60, 120 e 180 kg ha-1 de N) e uma testemunha, além dos parcelamentos (30 kg ha-1 de N na semeadura e o restante em cobertura; 60 kg ha-1 de N na semeadura e o restante em cobertura). A aplicação de sulfato de amônio enriquecido com 15N foi feita, na dose de 120 kg ha-1 de N, em subparcelas, previamente definidas, apenas no primeiro cultivo do milho. Foram feitas as seguintes avaliações: densidade de fluxo de água e de nitrato na profundidade de 0,80 m do solo (dose de 120 kg ha-1 de N); massa de 100 grãos; massa de matéria seca; teor de N; rendimento de grãos de milho; átomos % 15N nas plantas e solo; fração do N fertilizante na solução do solo na profundidade de 0,80 m, e no perfil do solo; balanço do N na sucessão de culturas; efeito residual do N fertilizante (aplicado no primeiro cultivo de milho) na aveia e no segundo cultivo de milho. Pelos resultados obtidos, concluiu-se que: a) a perda de nitrato total por lixiviação, a 0,80 m de profundidade, no 1º cultivo de milho, na dose de 120 kg ha-1 de N, foi de aproximadamente 96 e 68 kg ha-1, para os parcelamentos com 60 kg ha-1 e 30 kg ha-1 de N na semeadura, respectivamente, dos quais apenas 3 e 1 kg ha-1 foram provenientes do fertilizante nitrogenado; b) na dose 120 kg ha-1 de N, o tratamento com maior quantidade de N aplicado na semeadura (60 kg ha-1), no cultivo de milho do ano agrícola 2003/2004, proporcionou um maior aproveitamento do N do fertilizante (65%), em relação ao tratamento com a dose de 30 kg ha-1 na semeadura (45%) e que, para esse ano, a recuperação do N fertilizante pelo solo, na camada 0-0,80 m, para ambos os tratamentos, 60-60 e 30-90 kg ha-1, foi de 40 e 49%, respectivamente; c) Ainda referindo-se aos tratamentos 60-60 e 30-90 kg ha-1, do N remanescente do sulfato de amônio (120 kg ha-1), aplicado no primeiro ano agrícola (efeito residual), 3,72 e 1,79% foram utilizados pela aveia preta e 2,84 e 2,06% pelo milho cultivado no ano subseqüente (2004/2005), permanecendo no solo (camada 0-0,80 m), 30,19 e 33,47% após o cultivo de aveia preta e 16,79 e 17,91% após o segundo cultivo de milho, respectivamente, para os referidos tratamentos. / The general objective of this work was to study the dynamics of nitrogen in the soil-plant system of two maize crops with a black oats one in between, introducing the no-tillage system. Besides, fertilizing the first maize crop with 15N enriched nitrogen fertilizer, it was also objective of this work to assess the total and the derived from fertilizer nitrate leached at the depth of 0.8 m, the nitrogen use efficiency by the crops and the residual effect of the labeled nitrogen fertilizer. The experiment was carried in the experimental areas of ESALQ-USP in the country of Piracicaba (SP), in a yellow red latossol, sandy-loamy texture. The first maize crop was in 2003/2004 and the second one in 2004/2005. The experimental design was randomized blocks (3 x 2), with four replications. Treatments consisted of nitrogen (as ammonium sulphate) levels (60, 120 and 180 kg ha-1 of nitrogen) and the control, besides the splittings (30 and 60 kg ha-1 of nitrogen in the sowing and the rest in covering). The fertilization with 15N enriched ammonium sulphate in the first maize crop was made only for the level of 120 kg ha-1 of nitrogen, in subplots previously defined. The following measurements were carried out: soil-water and nitrate flux densities at the depth of 0.8 m (120 kg ha-1 of N); weight of 100 grains; weight of plant dry matter; nitrogen content; grain yield; total nitrogen; plant nitrogen use efficiency; fraction of the applied nitrogen in the soil solution at the depth of 0.8 m and in the soil profile; nitrogen balance in the crops succession; nitrogen residual effect in the black oat and the second maize crop. From the results, it could be concluded that: a) the leaching losses of total N, at the depth of 0,80 m, in the first maize crop, at the fertilization level of 120 kg ha-1 of N, were of 96 and 68 kg ha-1 for the splittings 60 and 30 kg ha-1 of N at sowing, respectively, from which only 3 and 1 kg ha-1 were derived from the nitrogen fertilizer; b) at the N fertilization level of 120 kg ha-1, the treatment with higher amount of applied N at sowing (60 kg ha-1) of the first maize crop (2003/2004) led to a higher plant N fertilizer recovery (65%) than the 30 kg ha-1of applied N at the sowing treatment (45%) and that, at the end of this crop cycle, the N fertilizer recovery by the 0-0,80 m soil layer, for 60-60 and 30-90 kg ha-1 treatments, were 40 and 49%, respectively; c) still for treatments 60-60 and 30-90 kg ha-1, from the total N applied in the first maize crop (120 kg ha-1), 3.72 and 1.79% were used by the black oats and 2.84 and 2.06% by the second maize crop, remaining in the soil (0-0.8 m layer), 30.19 and 33.47% after the black oats crop and 16.79 and 17.91% after the second maize crop, respectively for 60-60 and 30-90 kg ha-1 of N treatments.

L’acier 316L(N) est le matériau de référence pour les structures du circuit primaire des réacteurs nucléaires de quatrième génération, en raison de leur résistance mécanique à la température de fonctionnement, de l’ordre de 550°C. La thèse a permis de développer un modèle polycristallin, capable de prédire le comportement de ces aciers, basé sur la description du glissement viscoplastique des dislocation à haute température, de mise en œuvre simple et avec l’identification d’un nombre de paramètres matériau limité. La démarche de modélisation a été progressive. Lors de la première étape, nous avons proposé et validé une loi d'homogénéisation élasto-viscoplastique à champs moyens, grâce à de nombreux calculs par éléments finis, en considérant des durcissements plastique et des viscosités cristallines. Ensuite, un modèle de viscoplasticité cristalline, reposant sur les lois d’évolution des densités de différents types de dislocations, a été implémenté et les prédictions ont été validés en considérant un très grand nombre de résultats expérimentaux à faible. Le modèle a ensuite été enrichi afin de prendre en compte les mécanismes physiques supplémentaires observés à température élevée, comme la montée des dislocations, le vieillissement dynamique et l’apparition d’une structure de dislocation très hétérogène. Le modèle proposé nécessite uniquement l’ajustement de trois paramètres par identification inverse, utilisant seulement des essais de traction monotone avec saut de vitesse. Les prédictions du comportement mécanique en chargement uniaxial et cyclique sont également en bon accord avec les mesures expérimentales aux températures élevées. / The 316L(N) stainless steels is the reference material for the primary circuit structures of fourth-generation nuclear reactors. This alloy present high mechanical resistance at the operation temperature range of these reactors, of the order of 550 °C. This PhD allowed to develop a polycrystalline model based on the description of the viscoplastic dislocation slip at high temperatures, with straightforward implementation and with identification of a limited number of material parameters. The modeling process was progressive. In a first step, we proposed and validated a mean-field elastic-viscoplastic homogenization law, in comparison to numerous finite element calculations, considering crystalline plastic hardening and crystalline viscosity. Then, a model of crystalline viscoplasticity, based on the evolution laws of the different dislocations densities was implemented and the predictions were validated considering a very large number of experimental results at low temperature. The model was then enhanced to take into account the additional physical mechanisms observed at high temperature, such as dislocation climb, dynamic strain aging and the appearance of a very heterogeneous dislocation structure. The proposed model requires the adjustment of only three parameters by inverse identification, using only monotonic tensile tests at different strain rates. The mechanical behavior predictions in uniaxial and cyclic loading are also in good agreement with experimental measurements at high temperature.

Le travail a consisté, dans une première partie, à modéliser la dynamique des défauts ponctuels dans les mono-cristaux de silicium. Il s'est agi en premier lieu d'analyser en profondeur le modèle physique, pour introduire et comprendre le rôle de la thermodiffusion dans le modèle de transport-diffusion et recombinaison des interstitiels et des lacunes. Par une analyse asymptotique, nous sommes parvenus à prédire la composition du cristal en termes des densités de lacunes ou d'interstitiels. Nous avons également proposé un nouvel ensemble de paramètres matériels tenant compte de résultats d'expériences récentes sur la diffusivité des lacunes. Enfin, nous avons simulé numériquement le calcul des défauts ponctuels dans le procédé Czochralski de croissance de cristaux de silicium et l'avons validé par comparaison avec des résultats expérimentaux. Le travail principal dans cette thèse a consisté en l'élaboration d'une théorie mathématique permettant de décrire de manière rigoureuse la géométrie des dislocations dans les mono-cristaux. Par nature, ces défauts sont concentrés sur des lignes qui sont libres de former des réseaux complexes interagissant à leur tour avec les défauts ponctuels. Il s'est agi de proposer une théorie à l'échelle mésoscopique qui tienne compte à la fois de la multiformité des champs de déplacement et rotation tout en admettant que les effets non-élastiques soient concentrés dans la ligne. Les principaux champs intervenant dans cette théorie sont des densités de dislocations et de disclinations représentés par des tenseurs d'ordre 2 tenant compte à la fois de l'orientation de la ligne et des vecteurs de Frank et Burgers, qui sont des invariants caractérisant respectivement les défauts de rotation et de déplacement dans le cristal. Ces champs sont reliés à l'incompatibilité de la déformation élastique par l'intermédiaire de termes concentrés sur les lignes, qu'il a fallu décrire et formaliser dans un cadre mathématique rigoureux et cohérent. La description de la physique des dislocations a été rendue possible par l'application à la théorie des dislocations de certains nouveaux outils mathématiques tels, par exemple, la théorie des distributions, la théorie géométrique de la mesure, et la géométrie non-riemannienne. Enfin, l'homogénéisation de l'échelle mésoscopique vers l'échelle macroscopique des densités de dislocations, représentées par des tenseurs d'ordre 2, a permis de poser le problème à l'échelle du cristal, où les champs sont réguliers, obéissent à des lois de conservation, de constitution et d'évolution. Le travail de thèse s'est arrêté précisément au moment de modéliser l'échelle macroscopique, notamment les lois de constitution des densités de dislocations. / This thesis comprises two main parts and provides contributions to the fields of point- and line defects in single crystals. The point-defect transport, diffusion and recombination mechanisms are modeled in silicon crystals, whereas a theoretical approach is developped for the description of the geometry of dislocations. Therefore, plasticity, which is caused by the motion of dislocations, is not the topic of the present work. Dislocations are typical line-defects. Once generated during the growth of a silicon or other crystal, they can instantaneously multiply and generate dislocation networks, that render the material unusable for device manufacturing. We develop a theory to represent dislocated single crystals at the mesoscopic scale by considering concentrated effects along the dislocation line, as governed by the distribution theory combined with multiple-valued kinematic fields. Fundamental 2D identities relating the incompatibility tensor to the Frank and Burgers vectors are proved under global assumptions on the elastic strain, relying on the geometric measure theory, thereby giving rise to rigorous homogenisation from mesoscopic to macroscopic scale. The class of point-defects comprises the monoatomic defects which form the fundamental building blocks for grown-in defects in silicon crystals. A general model is build to conduct fully time-dependent and global simulations in order to predict the distribution of point-defects in a growing silicon crystal. Furthermore, the defect governing model is adapted in order to better agree with available measurements of self-interstitial and vacancy diffusion coefficients while respecting the V/G criterion, which characterises the interstitial-vacancy transition in the crystal. It is shown that introducing a thermal drift effect can facilitate the construction of a relevant model satisfying both conditions.