The characterization of natural climate variability is important in order to understand the climate response to natural forcings and to identify anthropogenic influences. The aim of this thesis is to reconstruct climate changes in the southwest of France, a region which is characterised by recurrent drought periods, where high resolution proxy records of the last millennia were lacking.The reconstruction is based on multiple proxies from two continental archives: speleothems and tree rings. Their combination can make use of the strengths of each archive while compensating their weaknesses. There are two principal objectives: first, to gain a better understanding of the climatic and non-climatic influences on each proxy; and second, to reconstruct drought periods in the past.The oxygen isotopic composition (δ18O) of speleothem fluid inclusions and tree ring cellulose is controlled to a large extent by the δ18O of precipitation, which can serve as a tracer of the atmospheric circulation. In order to interpret these proxies in terms of climate, it is necessary to understand how the climate signal becomes recorded in the proxy, and which processes modify the original signal during the formation of the archive.Measurements of δ18O in precipitation, cave drip water, and fluid inclusions in modern speleothem samples from Villars Cave demonstrated that the isotopic composition of cave drip water corresponds to the pluri-annual average precipitation. The speleothem fluid inclusions, in turn, preserve the isotopic composition of the drip water. Based on this calibration, it is possible to reconstruct drip water isotope variability using fluid inclusions in a more than 2000 year old stalagmite, which has been dated by laminae counting, as well as U-Th and 14C measurements. Changes in the cave environment, e.g. the vegetation cover, are indicated by other proxies from the same stalagmite (stable isotopes in calcite and trace element concentrations), but these changes do not seem to impact the fluid inclusion δ18O significantly.The isotopic composition of tree ring cellulose from Quercus spp. in the study area is strongly influenced by climate conditions during the summer. However, non-climatic influences on the isotopic composition of cellulose are identified. They are linked to the age of the trees and to site hydrology, and must be accounted for in the sampling and analytical procedures. Crossdated cores from living trees and timber wood in historic buildings near Angoulême are used to build an annually resolved chronology of cellulose δ18O. Significant correlations with meteorological data enable a calibration and a reconstruction of drought periods since 1360 AD.Lastly, this thesis explores a novel approach of integrating oxygen isotope records from speleothem fluid inclusions and tree ring cellulose from closely located sites to reconstruct both high- and low-frequency variability of droughts in the past.

This thesis consists of four self-contained essays in the sociology of educational stratification. Study I draws on newly collected survey data to assess the biases that arise in estimating socioeconomic differences in achievement when relying on parent and student reported data on social background. The main finding is that student reports on parental occupation overcome both the problem of misreporting that plagues other data collected from children, and the equally damaging problem of selective nonresponse among parents. Conditional estimates of ethnic disparities are relatively unaffected by these issues. Study II deals with student survey reports on the number of books in the home. A prominent string of authors has favoured this variable as a social background proxy over parental occupation or education based on its strong associations with educational outcomes. The paper applies various methods to large-scale student assessment data to show that these associations rest not on higher reliability as commonly assumed, but rather on two types of endogeneity. Low achievers accumulate less books and are also prone to underestimate their number. Study III uses survey and register data to study immigrant parents' education and its associations with children's achievement in recent Swedish cohorts. Two aspects of parental education are distinguished: the absolute years of schooling and a relative place in the source country's educational distribution. Parents' absolute education turns out to predict children's test scores and grades, whereas relative education is a better predictor of their educational aspirations. The result is of some consequence for studies seeking to assess ethnic disparities net of observed parental characteristics. Study IV extends the positional approach of Study III to understand immigrants' self-perceived social status and income satisfaction in European countries. Those higher educated by origin country than host country standards make more dismal assessments of their current situation than do other immigrants in otherwise similar circumstances. This is attributed to a social contrast mechanism and argued to be of relevance in understanding longer-term patterns of social and economic integration, including educational decisions made by the second generation. / Avhandlingen består av fyra fristående studier som alla berör utbildning och social stratifiering. Studie I undersöker med nyinsamlade enkätdata hur sociala skillnader i skolprestation riskerar att felskattas med bakgrundsuppgifter inhämtade från föräldrar respektive elever. Den viktigaste slutsatsen är att elevuppgifter om föräldrars yrke undviker mycket av den felrapportering som behäftar andra elevsvar, liksom det utbredda problemet med selektivt bortfall bland föräldrar. Villkorliga skattningar av etniska skillnader är relativt opåverkade av dessa metodproblem. Studie II granskar elevers uppgifter om antalet böcker i hemmet. En betydande litteratur har förespråkat denna variabel som ett mått på klasstillhörighet framför föräldrars yrke eller utbildning på grundval av starka samband med elevers studieresultat. Uppsatsen tillämpar en rad metoder på data från en internationell kunskapsutvärdering och finner att sambandens styrka inte vilar på högre tillförlitlighet som tidigare förmodats, utan på endogenitetsproblem av två slag. Lågpresterande elever ackumulerar färre böcker och är dessutom benägna att underskatta deras antal. Studie III använder enkät- och registerdata för att belysa utlandsfödda föräldrars utbildning och dess samband med prestationer bland svenska skolbarn. Två aspekter av utbildningsbakgrund särskiljs: föräldrars utbildningsår samt deras relativa placering i ursprungslandets fördelning. Absolut utbildning visar sig predicera elevers testresultat och betyg, medan relativ utbildning är en bättre prediktor för barns aspirationer. Resultatet är av betydelse för studier av etniska skillnader där statistisk kontroll görs för observerbara föräldraegenskaper. Studie IV tillämpar den positionella ansatsen från Studie III för att förstå utlandsföddas självupplevda status och inkomsttillfredsställelse i europeiska länder. Migranter som är mer högutbildade med ursprungslandets mått mätt än värdlandets tenderar att ha en mer negativ bild av sin nuvarande situation än andra i objektivt liknande omständigheter. Detta kan förstås i termer av sociala referensramar och framhålls som relevant i tolkningen av långsiktiga sociala och ekonomiska integrationsmönster, inklusive de utbildningsval som efterföljande generationer gör. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Manuscript. Paper 3: Manuscript. Paper 4: Manuscript.</p>

Climate north of the Atlas Mountain belt in NW Africa is dominated by extratropical disturbances. However, climatic controls to the south, where climate transitions from extratropical to tropical regimes, are poorly understood due to a paucity of both instrumental and palaeoclimate data. In this thesis past climate change between the High Atlas Mountains and Sahara Desert is reconstructed using the stable isotopic composition and radiometric dating of speleothems. A high-resolution record from the mid-Holocene and a discontinuous record covering the past 400,000 years are developed. Supplemented by U-Th dating of a further four samples, these records indicate increased humidity in this area concomitant with the wider African Humid Period, and indicate a link between the West African Monsoon and humidity north of 30&deg;N. Reconstructed glacial-interglacial scale increases in humidity overlap with "green Sahara" conditions and evidence a recurrent humid corridor connecting NW Africa and the central Sahara that is highly relevant to discussions of prehistoric human migrations. Evidence for a strong influence of high-latitude and solar forcing on decadal to millennial time- scales in this area is also presented. Further to this work, the potential of cadmium-to-calcite ratios as a novel proxy for palaeo-hydrology is confirmed using an annually-resolved trace element, stable isotope and calcite fabric dataset from a North Moroccan stalagmite. The first measurements of cadmium-to-calcite ratios in natural speleothem are here presented, and the palaeoclimatic significance and potential of this proxy for aiding the quantitative reconstruction of changes in calcite precipitation behaviour are demonstrated.

The work reported in this thesis applies a new isotope tracer, stable strontium isotopes (&delta;^88/86Sr), to address questions concerning changes in global climate that occur in response to continental weathering processes, and to constrain the modern marine geochemical Sr cycle. Stable Sr isotopes are a relatively new geochemical proxy, and as such their behavior needs to be understood in differing forms of marine calcium carbonate, the archives from which records of past stable Sr variability in the oceans can be constructed. Foraminifera, coccoliths and corals (both aragonite and high Mg calcite) acquire &delta;^88/86Sr values lighter than that of modern day seawater, (approximately 0.11, 0.05, 0.2 and 0.19 ‰ lighter than seawater at ~25°C respectively) providing a measureable offset which can be used to constrain the modern Sr outputs from the ocean and provide a better understanding of the modern Sr cycle. Using foraminifera as a sedimentary archive the first marine &delta;^88/86Sr record of seawater over the last two glacial cycles has been constructed, and used to investigate changing carbonate input and output over this 145 kyr period. Modelling of the large excursion of &delta;^88/86Sr to heavier values during Marine Isotope Stage (MIS) 3, reveals that this is more likely to be due to local changes in seawater or post-depositional alteration, rather then whole ocean changes. In the terrestrial environment &delta;&delta;88/86^Sr has been measured in the dissolved load of rivers from the Himalaya. It is found that, in general, rivers draining carbonate catchments possess lighter isotopic &delta;^88/86Sr values than those from rivers draining silicates. Covariations of either &delta;88/86Sr vs. &delta;30Si or &delta;^88/86Sr vs. 1/[Sr] can be used to distinguish between rivers draining different catchment areas.

No description available.

Este trabalho objetiva identificar quais os sentidos e significados atribuídos pelos médicos pediatras à Síndrome de Munchhausen por Procuração (SMP), bem como o manejo que a equipe médica tem diante de sua suspeita, e as possibilidades de encaminhamento frente a esse tipo de violência infantil. Para tanto, foi feito um levantamento bibliográfico nas principais bases de dados, referente ao período de 1977 até 2013, e uma pesquisa de campo. Essa consistiu na realização de entrevistas semi-dirigidas com pediatras de um hospital público de São Paulo. As entrevistas foram transcritas, lidas e categorias foram levantadas. Essas categorias foram refletidas à luz da literatura especializada e analisadas sob o vértice de alguns conceitos psicanalíticos que pudessem enriquecer a discussão. A literatura define a SMP, denuncia as características do perpetrador como indícios a serem observados pelo clínico para sua identificação e revela que esse é um quadro pouco conhecido e subnotificado. A pesquisa de campo mostrou que, mesmo para pediatras dedicados e experientes, a SMP revela-se como um enigma: a noção de que uma mãe possa, deliberadamente, fabricar ou provocar sintomas de doença ou deficiência no filho, é algo difícil de aceitar. Nesse sentido, o exercício de dar um sentido e um significado para a SMP foi atravessado pela manifestação dos impactos desse quadro no pediatra: ele se indaga, se surpreende e se angustia com o fenômeno em si. Eles, também, acreditam que o quadro seja subnotificado. Possibilidades interventivas foram evidenciadas por eles: o reconhecimento precoce, o acompanhamento familiar, o encaminhamento da mãe (na maioria das vezes, quem perpetua a violência) para atendimento psicológico e psiquiátrico, e o acionamento do Conselho Tutelar. Contudo, tais profissionais estão certos de que a precocidade na identificação é algo difícil de alcançar, a adesão do perpetrador ao tratamento psicológico não depende exclusivamente de seu encaminhamento e o acionamento dos agentes de proteção à criança nem sempre resolve a questão. Assim, acabam, na maioria das vezes, experimentando um sentimento de impotência diante da ideia construída (idealizada) sobre o que vem a ser o médico e seu exercício clínico. Nesse sentido, considerando as contribuições da psicanálise, o pediatra precisaria relativizar suas certezas, considerar a transferência, sustentar os ecos que esta complexa condição humana pode causar e prestar atenção na relação mãe-criança, para conseguir que o manejo e o encaminhamento fossem mais rápidos e eficientes. Para que nosso entendimento da SMP pudesse ser ampliado, seria de fundamental relevância que a mãe (perpetradora) pudesse ser escutada por um psicanalista, que teria acesso às suas motivações inconscientes. Essas novas pesquisas poderiam trazer um novo saber acerca dessa complexa condição, favorecendo, então, o desenvolvimento de novas possibilidades de intervenção / This study aims to identify the directions and the meanings assigned by pediatricians to Munchausen Syndrome by Proxy (MSBP or MBP), as well the handling of medical staff before its suspect and referral possibilities before this type of violence against children. Thus, a bibliographic research was done in major databases covering the period from 1977 to 2013, and a field research was conducted. This research consists of conducting semi-structured interviews with pediatricians of a public hospital in São Paulo City. The interviews were transcribed, read and categories were raised. These categories were reflected in the light of the literature and analyzed from the vertex of some psychoanalytic concepts that could enrich the discussion. The literature defines MSBP, reports the characteristics of the perpetrator as the evidences to be observed by the clinician to identify them and revels that this is an hardly known and an underreported medical framework. A field research showed that even to dedicated and experienced pediatricians, the MSBP is revealed as a puzzle: the idea that a mother can deliberately make or cause symptoms of illness or desability in her child is something hard to accept. Accordingly, the exercise of giving directions and meanings to MSBP was crossed by the manifestation of the impacts of this framework in pediatrician: he wonders, get surprised and grieves with the phenomenon itself. They also believe that this framework is underreported. Interventional possibilities were shown by them: early recognition, family monitoring, the referral of the mother (in most cases, who perpetuates violence) to psychological and psychiatric care, and contacting the Child Protective Council. However, such professionals are certain that early identification is a difficult thing to achieve, the acceptance of the perpetrator to the psychological and psychiatric treatment does not depend exclusively on their referral and the activation of the staff of the child protective council, does not always solve the issue. Thus end most of time, experiencing a feeling of powerlessness in the face of the constructed idea (idealized) about what is to be the doctor and his clinical practice. Accordingly in this sense, considering the contributions of the psychoanalysis, pediatricians need to relativize their convictions, consider transfer, sustain the echoes that this complex human condition may cause and watch the mother-child relationship, to achieve a faster and effective handling and referral. To expand our understanding of MSBP, it would be of fundamental relevance that the mother (perpetrator) could be listened by a psychoanalyst, who would have access to her unconscious motivations. These new researchs could bring new knowledge about this complex condition, then favoring the development of new opportunities for intervention

The transport control protocol (TCP) is one of the most heavily used protocols on the Internet, offering a reliable, connection oriented transport service. However, the quality of service (QoS) provided by the TCP protocol deteriorates when it is used over satellite IP networks. With the increased usage of Internet applications by the military in remote geographical regions, there is an increased need to address some of the shortcomings of TCP performance in satellite IP networks. In this research we describe our efforts at designing and testing a performance enhancing proxy (PEP) that can be used improve the QoS provided by the TCP service in large latency networks. We also show how one can use such a proxy to create a new transport service similar to the Available Bit Rate (ABR) service provided by ATM networks without needing ATM infrastructure, this new service offers a connection oriented, reliable, best effort transport service with minimal queuing delay, jitter and throughput variation.

Made available in DSpace on 2015-04-14T14:49:24Z (GMT). No. of bitstreams: 1 424471.pdf: 3818721 bytes, checksum: d6fbd6820f37d0e5f23b429ebe486f73 (MD5) Previous issue date: 2010-03-12 / Atualmente, diversos servi?os s?o disponibilizados pela Internet e h? uma crescente demanda por estas aplica??es. Considerando que a Internet n?o ? uma rede segura, a confidencialidade de informa??es que circulam na rede ? um fator de import?ncia cada vez maior. Visando solucionar este problema, v?rias t?cnicas de seguran?a surgiram e cada empresa as adotou em suas pol?ticas de uma forma diferente. Por?m com a tend?ncia de ado??o do modelo de Arquiteturas Orientadas a Servi?os, diferentes servi?os com diferentes pol?ticas de seguran?a necessitaram ser agrupados para que pudessem trabalhar em conjunto, o que acabou dificultando a cria??o de uma aplica??o que segue um determinado padr?o. Uma nova abordagem se faz necess?ria para facilitar a coexist?ncia destas t?cnicas de seguran?a de uma forma produtiva. Assim, este trabalho apresenta um modelo voltado ao tratamento autom?tico de caracter?sticas de seguran?a para servi?os ordenados em Arquiteturas Orientadas a Servi?o. Este modelo atua como um sistema intermedi?rio capaz de traduzir as t?cnicas de seguran?a para um formato determinado. Com base neste modelo ? apresentado um prot?tipo capaz de tratar automaticamente diferentes algoritmos de criptografia assim?trica, entre eles RSA, DSA e ECDSA. O objetivo do trabalho ? testar a efetividade do modelo por meio de um estudo de caso, apresentando uma situa??o que este pode ser adotado por aplica??es reais.

nÃo hà / A modelagem microscÃpica do fluxo de veÃculos na infraestrutura viÃria urbana tem se constituÃdo uma potencial ferramenta para a anÃlise do desempenho da seguranÃa viÃria (DSV) frente aos tradicionais mÃtodos de anÃlise com base nos estudos observacionais. Para consolidar essa abordagem existem desafios prÃticos e metodolÃgicos que foram tratados como objetivos nesta pesquisa, dentre os quais se destacam: (i) a identificaÃÃo de indicadores proxy eficientes para as anÃlises de seguranÃa nesse ambiente; (ii) a anÃlise dos algoritmos de microssimulaÃÃo quanto a sua eficÃcia de representaÃÃo dos processos de conduÃÃo no meio urbano, (iii) a definiÃÃo de um procedimento sistemÃtico de estimaÃÃo do DSV com o uso de microssimuladores de trÃfego e (iv) a validaÃÃo dos indicadores sintÃticos usados para medir o DSV. Diante deste contexto, esta pesquisa tem como objetivo geral apresentar uma contribuiÃÃo metodolÃgica para a utilizaÃÃo da microssimulaÃÃo de trÃfego nas anÃlises do DSV no processo de planejamento tÃtico operacional dos sistemas de transporte com foco nas interseÃÃes urbanas. O procedimento metodolÃgico proposto considerou a realizaÃÃo de cinco etapas: 1) seleÃÃo e caracterizaÃÃo do local de estudo, 2) codificaÃÃo do local no microssimulador, 3) planejamento da simulaÃÃo, 4) calibraÃÃo e validaÃÃo do modelo e 5) estimaÃÃo dos indicadores. A aplicaÃÃo do procedimento considerou trÃs interseÃÃes semaforizadas da cidade de Fortaleza, utilizando a plataforma de microssimulaÃÃo de trÃfego VISSIM. Os resultados alcanÃados indicaram que foi possÃvel estimar o DSV com relativo nÃvel de confianÃa e um procedimento complementar de validaÃÃo dos indicadores revelou um nÃvel de consistÃncia entre o nÃmero estimado de conflitos de interaÃÃes longitudinais e o nÃmero observado de colisÃes traseiras observadas em campo. / The microscopic modeling of traffic flow in urban road infrastructure has proven to be a potential tool for analyzing the performance of road safety (DSV) compared to traditional methods of analysis based on observational studies. To consolidate this approach there are practical and methodological challenges that have been treated as objectives in this research, among which are: (i) the identification of efficient synthetic indicators for the analysis of safety in this environment, (ii) the analysis of the microscopic algorithms and their effectiveness in the representation of the driving processes in urban areas, (iii) the definition of a systematic procedure for estimating the DSV using a microscopic platform and (iv) concerning the validation of synthetic indicators used to measure the DSV. Given this context, this research intended to provide a general methodological contribution to the use of microscopic traffic simulators for the analysis of the DSV in tactical and operational transportation systems planning process with focus on urban intersections. The proposed methodological procedure considered the completion of five steps: 1) selection and site characterization study, 2) coding the site in microsimulator 3) planning of the simulation, 4) calibration and validation of the model and 5) estimation of the indicators. The procedure considered three signalized intersections in the city of Fortaleza, using VISSIM  as simulation platform. The results indicated that it was possible to estimate the DSV with relative confidence level and a complementary procedure for validation of the indicators showed a consistent level of consistency between the estimated number of conflicts of longitudinal interactions and observed number of rear end collisions observed in the field.

Les écosystèmes côtiers sont soumis à de nombreuses perturbations entraînant la modification de leur structure et de leur fonctionnement. Afin d'estimer les parts respectives de la variabilité naturelle et de l'influence anthropique dans ce processus, et ainsi mieux prédire l'évolution de ces écosystèmes, il est nécessaire d'appréhender la variabilité de certains paramètres (température de l'océan, productivité biologique, apports de contaminants, etc.) avant toute influence anthropique majeure. Les mesures instrumentales de ces paramètres étant assez récentes, la reconstruction de la variabilité des écosystèmes côtiers avant la révolution industrielle ne peut se faire que par l'utilisation de proxies incorporés dans différents types d'archives.<br />Ce travail de thèse porte sur l'utilisation de la coquille de Comptopallium radula, un mollusque bivalve tropical de la famille des Pectinidae, pour reconstruire la variabilité de l'environnement dans le lagon sud-ouest de Nouvelle-Calédonie, un écosystème sous l'influence de diverses perturbations (réchauffement climatique, urbanisation, exploitation minière). Cette étude repose sur la comparaison de données géochimiques archivées dans la coquille de ce pectinidé au cours de sa vie, avec plusieurs variables physiques, chimiques et biologiques mesurées dans le lagon (suivi environnemental hebdomadaire). L'objectif de cette approche est de calibrer et de mettre en œuvre différents proxies climatiques et environnementaux.<br />Des marquages à la calcéine, effectués in situ sur des individus juvéniles, ont tout d'abord permis de démontrer que les stries de croissance présentes à la surface externe de la coquille de C. radula se forment avec une périodicité de 2 jours.<br />Des analyses isotopiques (δ18O et δ13C) ont ensuite été effectuées à partir de micro-échantillons de calcite prélevés le long de l'axe de croissance maximale de 6 coquilles juvéniles. Connaissant la périodicité de formation des stries, une date calendaire a pu être attribuée avec précision à chacun de ces prélèvements (résolution hebdomadaire). Nos résultats démontrent que les variations ontogéniques du δ18Ocalcite permettent de reconstruire les variations de la température de l'eau avec une précision de 1 °C. Quant à la composition isotopique du carbone (δ13Ccalcite), elle ne peut pas être utilisée comme proxy de la production primaire pélagique. Ses variations sont vraisemblablement contrôlées par le métabolisme benthique (sédiment et coraux).<br />Suite à ces analyses isotopiques, des analyses élémentaires ont été effectuées sur les mêmes coquilles à l'aide d'un système d'ablation laser couplé à un spectromètre de masse à plasma induit (LA-ICP-MS). Nos résultats démontrent que C. radula, au travers des concentrations en métaux dans sa coquille, ne peut être utilisé comme outil de bio-surveillance des apports en métaux dans le lagon : les variations ontogéniques de ces concentrations reflètent probablement les variations temporelles haute-fréquence des flux de métaux à l'interface eau-sédiment. Quant au baryum et au molybdène, leurs concentrations coquillières pourraient être utilisées comme proxies des biomasses de diatomées et de diazotrophes, respectivement.<br />Cette étude démontre donc le potentiel considérable de la coquille de C. radula comme archive eulérienne haute-fréquence de la variabilité climatique et environnementale dans le lagon sud-ouest de Nouvelle-Calédonie. Elle met également en lumière l'importance des processus benthiques sur l'incorporation des signaux géochimiques dans la matrice calcitique de la coquille. Son utilisation en tant qu'outil paléocéanographique est désormais conditionnée par la découverte de gisements fossiles de l'espèce.