Monitoring of cerebral oxygenation, cerebrovascular reactivity and circulatory function in preterm infants Brain injury in the preterm infant is associated with death and lifelong disability. Cerebral hypoxia and fluctuations in cerebral blood flow in the first two days of life have been implicated in the pathophysiology of haemorrhagic and ischaemic brain injury. Monitoring of haemodynamic changes during the early transitional circulation from in-utero to ex-utero life are currently based on standard measurements of systemic oxygenation and mean arterial blood pressure, with no reliable assessment of end-organ perfusion. In this thesis, measurements using near-infrared spectroscopy (NIRS) and functional echocardiography were made to assess cerebral perfusion and systemic blood flow in a cohort of preterm infants undergoing intensive care. This thesis is divided into four sections: i) The feasibility of continuous monitoring of cerebral oxygenation and cerebrovascular reactivity is demonstrated in a series of case reviews, and the association between cerebral oxygenation and cerebrovascular reactivity with outcome of brain injury and mortality is described. ii) Combining measurements of systemic blood flow with end organ perfusion was applied to define MABPOPT in preterm infants based on an index of cerebrovascular reactivity. Deviations below MABPOPT were associated with intraventricular haemorrhage and mortality. iii) The complexity of brain and systemic signals was studied by using multi-scale entropy analysis. Most studies using cerebral NIRS or systemic measurements of blood flow use linear analysis; however, a complex biological system, such as the human brain, includes many regulatory mechanisms that interact in a complex manner, resulting in effects that cannot be understood wholly through the analysis of its individual constituents. Lower complexity of brain signals was observed in infants who developed intraventricular hemorrhage or died. iv) Changes in systemic and cerebral oxygenation in a cohort of preterm infants in the first 48 hours of life was assessed using functional echocardiography. The patterns of changes in cardiac output and cerebral oxygenation in infants who did and did not have intraventricular haemorrhage are discussed. Furthermore, the relationship between the presence of a haemodynamically significant ductus arteriosus and brain injury is assessed.

abstract: Research on self-regulatory variables like mindfulness and effortful control proposes strong links with physical and mental health outcomes across the lifespan, from childhood and adolescence to adulthood and old age. One pathway by which self-regulation may confer health benefits is through individual differences in reports of and emotional responses to daily negative and positive events. Mindfulness is broadly defined as non-reactivity to inner experiences, while effortful control is broadly defined as attentional and behavioral regulation. Mindfulness and effortful control have both been conceptualized to exert their beneficial effects on development through their influence on exposure/engagement and emotional reactivity/responsiveness to both negative and positive events, yet few empirical studies have tested this claim using daily-diary designs, a research methodology that permits for examining this process. With a sample of community-dwelling adults (n=191), this thesis examined whether dispositional mindfulness (i.e., non-reactivity of inner experience) and effortful control (i.e., attention and behavioral regulation) modulate reports of and affective reactivity/responsiveness to daily negative and positive events across 30 days. Results showed that mindfulness and effortful control were each associated with reduced exposure to daily stressors but not positive events. They also showed that mindfulness and effortful control, respectively, predicted smaller decreases in negative affect and smaller increases in positive affect on days that positive events occurred. Overall, these findings offer insight into how these self-regulatory factors operate in the context of middle-aged adults’ everyday life. / Dissertation/Thesis / Masters Thesis Psychology 2018

A reatividade, considerada como uma característica comportamental apresentada pelos bovinos diante das práticas de manejo, mais evidente nos animais de raças zebuínas, em associação com medidas fisiológicas pode se mostrar como um indicativo de estresse, dor ou desconforto, além de estar intimamente relacionada a diversas respostas produtivas apresentadas pelos animais dessa espécie. Desse modo, há necessidade de agregar essa característica, facilmente observável, ao conjunto de fatores que determinam o desempenho do animal. Para tanto, o presente estudo teve como objetivo avaliar a reatividade de novilhos Nelore confinados em dois diferentes sistemas (Curral ou Baia como tratamentos), e sua relação com o cortisol plasmático, temperatura corporal e desempenho. Foram avaliados 36 novilhos quanto às reatividades apresentadas durante o manejo de pesagem, a cada 28 dias, utilizando uma escala de Escores de Reatividade (ER) variando de 1 a 5, sendo 1 o valor atribuído ao animal mais calmo e o 5, ao animal mais reativo. Também foram coletadas amostras de sangue para posterior dosagem do cortisol plasmático, além do acompanhamento dos ganhos de peso durante todo o período. Não foram encontradas diferenças significativas da reatividade quanto ao sistema de alojamento, porém houve uma relação desse mesmo parâmetro com o tempo de permanência no confinamento para os animais nos dois tratamentos. A reatividade, quando relacionada aos valores de cortisol, não foi diferente entre os tratamentos, entretanto, esse resultado foi significante dentro do grupo dos animais alojados em Baias. O tempo de confinamento influenciou os níveis de cortisol apenas nos animais alojados em Curral. Os níveis de cortisol foram diferentes entre os tratamentos, e quando relacionados ao tempo de confinamento, evoluíram de forma inversa, tendo diminuído nas baias e aumentado nos currais. Não houve interação entre reatividade e desempenho ou entre reatividade e temperatura corporal, que foi influenciada pelos níveis de cortisol. / Reactivity as a behavioural trait of bovines presented during the handling and more obviously in Zebu cattle, in association with physiological measures can reveal as an indicative of stress, pain or discomfort, beyond being strongly related with several productive answers presented by the animals of this specie. Therefore, it is necessary to add this trait to the group of responsible factors for animals\' performances. The present study was conducted to evaluate the reactivity of Nellore steers in different feedlot systems (Stockyard and Individual pen as treatments) and its relationship with plasmatic cortisol, body temperature and performance. Thirty six Nellore steers had their reactivity evaluated during routine weighing. Blood samples were collected for cortisol analyses and the weight gains were measured during all the period. The results showed that the reactivity score did not differ between feedlots systems but there was a relation of this trait with feedlot time. There was no difference between reactivity and cortisol levels for the treatments, but this result was significant inside of the stall animals group. Feedlot time influenced the cortisol levels only for the stockyard steers. Cortisol levels differed between treatments, having increased in stalls animals and decreasing in stockyard animals. No interactions were presented between reactivity and performance, or reactivity and corporal temperature, but this last trait presented relation with cortisol levels.

O presente trabalho visa contribuir com o desenvolvimento sistemático de novas metodologias experimentais da medida da reatividade de arranjos físseis subcríticos, utilizando: estatísticas de alta ordem das contagens de nêutrons com detectores no modo pulso, o recente conceito de reatividade generalizada, e as instalações do reator IPEN/MB-01. Este trabalho reuniu em um só texto diversos aspectos da implementação destes tipos de medidas. Diferentemente das demais técnicas utilizadas nas medidas da reatividade subcrítica, as metodologias apresentadas neste trabalho tem o potencial para permitir a medida experimental da reatividade subcrítica sem a necessidade da estimativa prévia de quaisquer outros parâmetros cinéticos, obtidos de forma teórica ou experimental, calibração de fontes externas ou detectores.A princípio, os métodos estatísticos de alta ordem das contagens de nêutrons permitem obter diretamente o valor da subcriticalidade (ou o fator de multiplicação) de um arranjo físsil, independentemente do modelo de física subcrítica utilizado, sem a utilização de infra-estrutura diferenciada (como uma fonte pulsada de nêutrons), sendo uma extensão natural das metodologias que utilizam estatísticas de ordens inferiores - por exemplo, Feymann-. E este conteúdo estatístico diferenciado dos momentos de altas ordens das contagens de nêutrons, o principal motivador da implementação deste trabalho. Apesar de suas potencialidades, a implementação experimental do método esbarra no tempo e taxa de aquisição de dados; ou seja, na quantidade de conteúdo estatístico necessária para a obtenção de medida útil. Exatamente esta dificuldade impediu a obtenção de uma medida útil/prática nas instalações do reator IPEN/MB-01. Existem, entretanto, outras formas de explorar estatísticas ordem superior. Por exemplo, uma extensão do método de Rossi- sugerida neste trabalho pode utilizar auto bi-correlações (coincidências triplas não acidentais de contagens). A despeito do alto valor das incertezas, os aspectos estatísticos fundamentais de uma medida foram preservados nos métodos empregados neste trabalho. O método das auto bicorrelações é conceitualmente mais robusto contra as influências do tempo morto do sistema de aquisição de dados. Ao longo de sua execução, o presente trabalho visou preencher algumas lacunas de procedimentos experimentais aparentemente pouco abordadas por outros autores, permitindo estabelecer métodos estatisticamente mais rigorosos. Entre as contribuições neste sentido destacam-se, entre outras, as correções por tempo morto ou as geradas pela correlação entre os parâmetros estatísticos em tela. Do ponto de vista teórico, este trabalho sugere duas maneiras originais de abordar o mesmo problema da utilização de estatísticas de altas ordens: (a) auto bicorrelações; e (2) os biespectros de densidade de espectral de potência própria, sendo o primeiro explorado experimentalmente/estatisticamente em detalhes. / The present work aims to contribute to the systematic development of new experimental methods of measuring the reactivity of any subcritical fissile arrangements using: high-order statistics of neutron counts from neutron detectors working in pulse mode, the recent concept general reactivity, and the IPEN/MB-01 facility. This thesis brought together in a single text various aspects concerning the proper implementation of these types of measures. Unlike other techniques used in measurements of subcritical reactivity, the methodologies presented in this thesis has the potential to allow the experimental measurement of subcritical reactivity without the prior estimate of any other kinetic parameters, obtained from experiments or from theoretical considerations, external sources calibrations or detectors e ciency measurements. At first, the high-order statistical methods of neutron counts allow to obtain directly the value of the subcriticality (or multiplication factor) from an fissile arrangement regardless the type of subcritical physical theory, and also without the use of unusual infrastructure (such as a pulsed neutron source). These methods are a natural extension of those that use lower order statistics - for example, Feymann-. The greater information content in high order statistics of neutron counting is the main reason for the implementation of this work. Despite its potential, the experimental implementation of the method found huge problems concerning acquisition time and rate of data acquisition. This difficulty overcome any effort in order to obtain a useful measurement inside the IPEN/MB-01 nuclear reactor (a critical facility). However, there are other ways to exploit higher order statistics. For example, an extension of the Rossi- method suggested in this thesis used self bicorrelations. Though the high variance values of obtained results, the fundamental statistical requirements of a measurement were preserved, once the proposed methodologies are observed. It was proposed a methodology to handle dead time issues, in order to allow one to carry out measurement at higher detection rates. Throughout its execution, this thesis aimed to fulfill some gaps in the experimental procedures apparently not addressed by other authors, allowing the establishment of more rigorous statistical procedures. Regarding those contributions, dead time corrections stands out together with the concerning for correlation treatment between the statistical parameters. From the theoretical point of view, this thesis suggests two new ways to address the same problem of using high order statistics of neutron detections in pulse mode: (1) self-bicorrelations, and (2) self-bispectra (power spectral density in two axis). The first was experimentally tested and exhaustively detailed, the second one was only suggested as a theoretical speculation to be confronted against experimental evidence

Because of the impact of stress on health, it is important to understand the variables that underlie cardiovascular reactivity to stress because it may lead to more focused targets of intervention for helping people to reduce or otherwise better manage their stress. The purpose of the present study was to answer the following questions: does lack of eudaimonic well-being (a combination of psychological and social well-being) predict increased cardiovascular reactivity to stress in a clinically distressed population? And does increased eudaimonic well-being protect against increased cardiovascular reactivity to stress when hedonic well-being (a combination of positive affect and life satisfaction) is low and depression and stress are high? If so, then it may be possible to reduce the effects of stress on health even if depression and stress are present. One hundred twenty-nine college students (ages 18-29) who were clinically distressed were administered a questionnaire that included questions about demographic variables and measures of hedonic and eudaimonic well-being, depression, and general perceived stress. After answering the questionnaire, a baseline reading of cardiovascular activity was taken. After the baseline reading, participants were subjected to the Trier Social Stress Test (TSST), an interpersonal stressor that consists of an anticipation period, a speech, and a math task. Measurements of cardiovascular activity were taken throughout the TSST. I predicted that lower levels of eudaimonic and hedonic well-being, mental health, and higher amounts of general perceived stress would predict increased cardiovascular reactivity to the TSST as measured by systolic blood pressure, diastolic blood pressure, and heart rate. Then, should the prior hypothesis be true, I predicted that higher eudaimonic well-being will suppress the effect of lower hedonic will-being, lower mental health, and higher general perceived stress on cardiovascular activity to acute stress. Results of the study found no effect of eudaimonic well-being, hedonic well-being, depression, and general perceived stress on cardiovascular reactivity during the TSST. The results suggest that there is no relationship between well-being, depression, and general perceived stress and cardiovascular reactivity to stress in a young college student population.

Les verres nucléaires sont synthétisés par réactions chimiques à haute température entre un précurseur vitreux (fritte de verre) et un déchet calciné (calcinat) dans un procédé de calcination-vitrification. Le déchet est d'abord séché et dénitré (calcination) avant d'être mélangé à la fritte de verre (vitrification). Une succession de processus physico-chimiques d'imprégnation, diffusion, cristallisation et dissolution, est mise en jeu afin d'intégrer les éléments présents dans le calcinat au sein du réseau vitreux. Ces réactions, dépendantes de la composition des précurseurs et des conditions d'élaboration, doivent être complètes afin d'assurer l'homogénéité du verre et garantir son comportement à long terme. Ce travail a pour objectif de déterminer les réactions chimiques entre les précurseurs et de quantifier les cinétiques réactionnelles afin d'identifier in fine les processus responsables de leur limitation. Un système simplifié constitué d'une fritte de verre de type alumino-borosilicate de sodium et d'un calcinat contenant du nitrate de sodium et de l'oxyde d'aluminium (composés majeurs présents dans les calcinats complexes) est complexifié progressivement afin de déterminer l'influence des éléments de faible solubilité, présents initialement dans les solutions de produits de fission à vitrifier. Les cas des oxydes de molybdène et de néodyme sont en particulier étudiés. Les conditions de formation (temps, température) des phases cristallines de type molybdates (sodium, calcium) et aluminates (sodium, néodyme) ainsi que leur domaine de stabilité dans les calcinats sont déterminés. Les cinétiques de dissolution de ces phases dans la fritte de verre sont modélisées. Il est montré que la dissolution du molybdène, mis en évidence sous forme Na2MoO4, est contrôlée d'une part par la solubilité thermodynamique du MoO3 dans le verre, indépendamment de la dissolution des aluminates de sodium. D'autre part, les cinétiques de dissolution de Na2MoO4 et des aluminates présentent un comportement arrhénien avec la température dont les valeurs des énergies d'activation sont proches de celles de la viscosité du verre. Ces travaux décrivent également les mécanismes de formation d'intermédiaires réactionnels à l'origine de la cristallisation de la " yellow phase " (riche en oxydes de molybdène, d'alcalins et d'alcalinoterreux) pouvant se former dans des verres plus complexes. / Nuclear waste glasses are produced by chemical reactions between a solid waste (calcine) and a glassy precursor (glass frit) through a high-temperature vitrification process. The waste is first dried and calcined (to lose water and nitrogen respectively), then mixed with the glass frit. A succession of physicochemical processes of impregnation, diffusion, crystallization and dissolution is involved in order to incorporate the radioactive elements within the glassy network. These reactions, which are dependent on the precursor composition and the synthesis conditions, must be complete to ensure the homogeneity of the glass and to guarantee its long-term behavior. The aim of this work is to determine the chemical reactions between the precursors and to quantify the reaction kinetics in order to identify the processes responsible for their limitation. A simplified system consisting of a sodium-aluminum borosilicate glass frit and a calcine containing sodium nitrate and aluminum oxide (the principal oxides present in complex calcines) is progressively complexified to determine the influence of low solubility elements initially present in the fission product solutions to be vitrified. The cases of molybdenum and neodymium oxides are the focus of attention. The formation conditions (time, temperature) of crystalline molybdates (sodium, calcium) and aluminates (sodium, neodymium) and their range of stability in the calcines are determined. The dissolution kinetics of these phases in the glass frit is modeled. It is shown that the dissolution of molybdenum, as Na2MoO4, is controlled by the thermodynamic solubility of MoO3 in the glass. It is independent of the sodium aluminate dissolution. For both, Na2MoO4 and sodium aluminates, dissolution reactions present an Arrhenian behaviour and the activation energies are close to that of the viscous flow. This work also describes the formation mechanisms of intermediate phases which can lead to the crystallization of the "yellow phase" (enriched in molybdenum, alkali and alkaline-earth oxides) that can form in more complex glasses.

Density functional theory (DFT) has become the most widely used first-principles computational method to simulate different atomic, molecular, and solid phase systems based on electron density assumptions. The complexity of describing a many-body system has been significantly reduced in DFT. However, it also brings in potential error when dealing with a system that involves the interactions between metallic and non-metallic species. DFT tends to overly-delocalize the electrons in metallic species and sometimes results in the overestimation of reaction energy, metallic properties in insulators, and predicts relative surface stabilities incorrectly in some instances. There are two approaches to overcoming the failure of DFT using standard exchange-correlation functionals: One can either use a higher level of theory (and thus incur a greater computational cost) or one can apply an efficient correction scheme. However, inaccurate corrections and improper calculation models can also lead to more errors. In the beginning of this dissertation, we introduce the correction methods we developed to accurately model the structure and electron density in material surfaces; then we apply the new methods in surface reactivity studies under experimental conditions to rationalize and solve real life problems. We first investigate the post-DFT correction method in predicting the chemisorption energy (Echem) of a NO molecule on transition metal surfaces. We show that DFT systematically enhances back-donation in NO/metal chemistorption from the metal d-band to NO 2π* orbital, and relate the back-donation charge transfer to the promotion of an electron from the 5σ orbital to the 2π* orbital in the gas-phase NO G2Σ-←X2Π excitation. We establish linear relationships between Echem and ΔEG←X and formulate an Echem correction scheme to the (111) surfaces of Pt, Pd, Rh and Ir. As a precursor to further optimization of DFT corrections on transition metal oxide surfaces, we systematically compare the alumina (α-Al2O3) and hematite (α-Fe2O3) (0001) surfaces to study how the atomic positions treatment during geometry optimizations would affect the electronic structure and modeled reactivity, since they are often reported to have a minimal effect. Our results suggest that both can vary significantly in quantitative and qualitative ways between partially constrained or fully relaxed slab models. We continue to use the α-Fe2O3 (0001) surfaces to optimize the Hubbard U method implemented in DFT that determines the Coulomb repulsion correction (Ud) to localize Fe d-electrons. It successfully restores the insulating properties of bulk hematite, but underestimates the stability of the oxygen-terminated surface. It is mainly due to the fact that all the chemically distinct surface Fe atoms were treated the same way. Here we develop a linear response technique to derive specific Ud values for all Fe atoms in several slab geometries. We also find that in a strongly correlated system, the O p-orbitals also need the Hubbard correction (Up) to accurately predict the structural and electronic properties of bulk hematite. Our results show that the site-specific Ud, combined with Up as Ud+p, is crucial in obtaining theoretical results for surface stability that are congruent with the experimental literature results of α-Fe2O3 (0001) surface structure. Besides methodology development, we continue to apply our specific Ud+p method in the engineered application of the Chemical Looping Combustion (CLC) process in which transition metal oxides play the role of oxidizing fuel molecules for full CO2 capture. Current molecular dynamic studies use partially constrained surface models to simulate the CH4 reaction on hematite surfaces without the detailed comparison of the early stage adsorption products. Here we use hematite (α-Fe2O3) and magnetite (Fe3O4) surfaces as analogous to systematically study the early adsorption products of CH4. Our results show that the reaction favors the homolytic pathway on O-terminated surface, and that as a reduced form of hematite, the magnetite surface also shows excellent reactivity on CH4 dissociation. Knowing how to simulate DFT surface model properly we continue to enrich our theoretical methods for more complicated systems under aqueous conditions. We focus on various structures of the lithium-ion battery material, LiCoO2 (LCO) (001) surface, involving hydroxyl groups. We assess the relative stabilities of different surface configurations using a thermodynamic framework, and a second approach using a surface-solvent ion exchange model. We find that for both models the –CoO–H1/2 surface is the most stable structure near the O-rich limit, which corresponds to ambient conditions. We also found that this surface has nonequivalent surface geometry with the stoichiometric –CoO–Li1/2 surface, leading to distinct band structures and surface charge distributions. We go on to probe how those differences affect the surface reactivity in phosphate anion adsorption. All of the work presented in this dissertation reveals the importance of accurately modeled material structures in theoretical studies to achieve correct physical properties and surface reactivity predictions. We hope our DFT correction schemes can continue to contribute to future surface studies and experimental measurements, and to enlighten new ideas in future DFT methodology improvements.

Smoking is now the leading cause of preventable death and disease in women. Understanding women's motivations to smoke is important in developing effective cessation and relapse prevention programs. Previous descriptive, correlational, and quasi-experimental research has established that weight concerns and negative body image are associated with tobacco smoking, cessation, and relapse, particularly among young women. This study, building upon a previous experimental study (Lopez, Drobes, Thompson, & Brandon, 2008), examined whether activation of negative body image cognitions would produce greater urges to smoke and would affect actual smoking behavior. A randomized 2 X 2 crossed factorial, between-subjects design (body image manipulation X smoking cue manipulation) was conducted with 133 female college smokers. The body image manipulation involved trying on a one-piece bathing suit or evaluating a purse, and the smoking cue manipulation included the presentation of their pack of cigarettes or a stapler. Participants completed pre-intervention measures assessing smoking history, trait body dissatisfaction, trait self-objectification, and trait affect. State levels of urge to smoke, mood, and body dissatisfaction were assessed after the manipulations. It was hypothesized that main effects on the measures of smoking motivation (i.e., self-reported urges to smoke and topographical measures of smoking behavior) would be found for the body image manipulation, with trait body dissatisfaction and/or trait self-objectification moderating the body image manipulation and state negative affect serving as a mediator. Results indicated that trying on a bathing suit, which increased body dissatisfaction, did increase reported urges to smoke, particularly those urges related to reducing negative affect. Women assigned to the bathing suit condition also subsequently took a greater number of puffs from their cigarette than those who evaluated the purse. (No main effects were found for the smoking cue manipulation). No moderation effects were found, but the effect on smoking urges by the body image manipulation was mediated by state negative affect. This study provides additional support, through an experimental design, that situational challenges to body image influence smoking motivation, and that this effect occurs, at least in part, via increases in negative affect. Theoretical and applied implications are discussed.

Staff management research in group home settings has involved direct observation of staff performance during pre-treatment and treatment conditions. Collecting accurate research data is crucial to analyze treatment effects; however, reactivity to being observed has been cited as a limitation in several studies. The current study evaluated the use of a tactile prompt, self-monitoring, and feedback to increase positive interaction in a group home setting. Direct support professional staff were trained on the purpose and use of the MotivAider which provided tactile prompts to remind them to engage in positive client interaction. Reactivity was assessed by having a confederate observe staff positive interaction when the supervisor was present and when the supervisor was absent. The effects of supervisor presence were evaluated using an alternating treatment within a multiple baseline across participants' research design. Results showed that 2 of 4 participants increased positive interactions only when a supervisor was present and 2 other participants increased positive interaction only after receiving feedback.

Eating disorders and non-suicidal self-injury (NSSI) are pervasive behaviors that typically begin in early to mid-adolescence. They commonly co-occur, resulting in increasingly negative psychological and physical outcomes than either behavior alone. Emotion reactivity and family functioning have been studied in relation to both eating disorders and NSSI. Both constructs have demonstrated strong relationships to these behaviors, but emotion reactivity appears to be more strongly associated with NSSI, while family functioning appears to be more strongly related to eating disorders. The current study sought to determine whether emotion reactivity and family functioning could differentiate between adolescents with only an eating disorder, only NSSI, or both behaviors. Data were collected from 229 adolescents in both inpatient and outpatient treatment programs who reported either a diagnosed eating disorder, past week NSSI, or both. Results indicated that increased emotion reactivity increased the likelihood that an individual was categorized in the NSSI only group compared to the eating disorder group and the comorbid group. There was no main effect for family functioning across all analyses. Based on these results, emotion reactivity may be an important variable to consider in distinguishing between adolescents with eating disorders who may or may not engage in NSSI, and may provide further insight when examined longitudinally