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[pt] O Asset Liability Management (ALM) é uma ferramenta essencial para uma administração eficaz de bancos, seguradoras e fundos de pensão, principalmente no que diz respeito ao monitoramento e controle de riscos enfrentados por estas instituições. Dentre estes riscos, o de taxa de juros é uma das principais fontes de perda potencial para uma instituição financeira. Este trabalho tem como objetivo estudar formas de se controlar este tipo de risco. Para tal, será estudada a fundo a estratégia de imunização de carteiras. Esta estratégia consiste em montar uma carteira ótima de forma que a mesma seja imune a variações na taxa de juros, ou seja, independente das variações que ocorram nas taxas de juros, o valor da carteira não se altere. Dois modelos de imunização de carteiras de renda fixa propostos na literatura são estudados detalhadamente. Um utiliza a técnica de análise de componentes principais (ACP), imunizando a carteira na direção destes componentes. O outro modelo usa um método de minimização do risco estocástico. Em ambos, um exemplo ilustrativo é apresentado e uma aplicação prática é feita utilizando-se dados de um fundo de pensão no Brasil (este tipo de estratégia é de extremo interesse para fundos de pensão, que possuem longos fluxos de passivos e que desejam garantir que suas obrigações sejam sempre satisfeitas). Por fim, é feita uma análise dos resultados obtidos após a imunização. / [en] Asset Liability Management (ALM) is an important tool used in the administration of banks, insurance companies and pension funds, especially for monitoring and controlling the risk those institutions usually face. Among the various types of risk, the interest rate risk is one of the main sources of potential loss for a financial institution. This dissertation aims to study ways of controlling this type of risk. Thus, we will thoroughly study the strategy used for Asset Liability Management. This strategy consists in assembling an optimum portfolio in a way that it becomes unaffected by changes in the interest rates. A couple of immunization models for fixed rate portfolios are studied in detail. One of them employs the method of principal component analysis (PCA), immunizing the portfolio in the direction of those components. The other model minimizes the stochastic risk. In both of them, we present an example and use of the method in a Brazilian pension fund (this strategy is highly interesting to pension funds since they work with a long liability cash flow and want to certify their obligations will always be satisfied). Finally, we analyse the results obtained with the two methods.

Objectives: To determine the physiological strain on industrial workers under thermal stress on extended shifts. To continuously measure deep body core temperatures, heart rates, fluid intake, changes in hydration state and physical fatigue in order to establish acceptable levels of physiological strain. To develop a rational heat stress index compatible with these limits. To design working-in-heat protocols for a self-paced workforce. Methods: A series of studies was conducted over 77 shifts on a group of approximately 50 male volunteers working in thermally stressful environments. Continuously- recorded deep body core temperatures, heart rates, fluid consumption, urinary specific gravity and physical fatigue were measured and recorded. A new field protocol was developed to assess physical fatigue over the working shift. An original methodology was developed to allow any heat stress index to be assessed on a comparative basis with any other index. A review of the commonly used occupational heat stress indices was conducted. A new rational heat stress index was developed, based on existing biophysical relationships and recommended physiological strain limits of deep body core temperature and sweat rate. New protocols designed for self-paced work incorporating the significant risk factors for heat illness were developed and implemented in a workforce of approximately 2000 workers exposed to heat stress. The previous protocols used a shortened shift as the primary intervention to protect worker health. The subsequent protocols removed the shortened shift and replaced this with a range of other interventions. Deep body core temperature, heart rate, fluid consumption, hydration state and fatigue were measured before and after the changes in protocols. / Results: Comparisons of heat stress indices confirmed the wide divergence in guidance provided by many of the commonly-used indices in terms of acceptable working environments. It also highlighted a number of serious shortcomings in the most widely-used indices, especially WBGT and ISO7933. A new, rational heat stress index called Thermal Work Limit (TWL) was developed. This included development of a computer model incorporating key thermal physiological parameters (deep body core temperature, mean skin temperature, sweat rate, skin wettedness). There was no increase in heat stress (as indicated by average workplace environmental conditions), deep body core temperature, mean heart rate, or changes in hydration status after the changes in protocols. Average environmental conditions were severe (WBGT 30.9° C, sd 2.0° C, range 25.7-35.2° C). Environmental conditions in the study were much hotter than those considered acceptable under standards such as the ACGIH. The results showed that miners regularly exceeded those limits allowable under most current indices in terms of maximum deep body core temperature (avg 38.3° C, std dev 0.4° C), maximum temperature rise (1.4° C, 0.4° C) and maximum heat storage (431 kJ, 163 kJ), without reporting any symptoms of heat illness. A significant component of the observed elevated core temperatures was due to the normal circadian rhythm, which was measured at 0.9° C (std dev 0.2° C). Evidence was found that workers "self-pace" when under thermal stress. Fluid intake averaged 0.8 l/h during exposure (sd 0.3 l/h, range 0.3-1.5 1/h). Average urinary specific gravity at start-, mid- and end of shift was 1.0251, 1.0248 and 1.0254 respectively; the differences between start and mid-shift, mid and end-shift, and start and end-shift were not significant. / However, a majority of workers were coming to work in a moderately hypohydrated state (urinary specific gravity avg 1.024, std dev 0.0059). Involuntary dehydration was not found to occur in the study group. This is in contrast to several other studies and some of the leading heat stress standards, which are based on the premise that workers are unable to maintain their hydration status when working in the heat, even when their fluid consumption is equal to their sweat rate. Continuous heart rates measured over a shift (avg 103 bpm, 14% of shifts exceeding avg 110 bpm, 5% exceeding avg 120 bpm) were in excess of those allowable under most current indices On average, workers experienced a peak 10- minute heart rate of 140 bpm and a peak 30-minute heart rate of 130 bpm during their shifts. There was a significant increase in fatigue in the first half of the working shift (P=0.001), with workers on average showing a significant recovery in the second half of their shift (p=0.04). Conclusions: Current heat stress indices provide little common agreement as to acceptable levels of thermal strain or stress for workers, at equivalent levels of environmental stress. IS07933 is seriously flawed and the ACGIH WBGT guidelines are too conservative for acclimatised workers and are unlikely to become widely adopted by industries with well-acclimatised workers. Many of the existing indices show internal inconsistencies. / Most of the physiological heat strain limits used in existing rational heat stress indices (in terms of deep body core temperature and heart rate) are conservative for self-paced, acclimatise d, non-dehydrating male workers. Involuntary dehydration is not unavoidable when acclimatised workers are exposed to thermal stress. Heat stress standards should not limit heat exposure durations for self- paced workers who have access to water on the basis of an unavoidable body water loss. Physical fatigue does occur in workers under heat stress on extended shifts; however, most workers show a significant increase in fatigue in the first half of their shift; whereas data indicates self-paced workers undergo significant recovery in terms of fatigue in the second half of the shift. As the heat exposures in this study cover a wide range of temperatures, humidity levels, wind speeds, body morphology and VO2max, these conclusions are applicable to most thermally stressful settings involving well-informed, well-acclimatised and self-paced male workers. The major category of work type not covered by this study is that of workers in fully-encapsulated (vapour-barrier) protective clothing. In addition, this study examined acute effects of heat stress and strain, not effects that might only be manifest with chronic exposure to heat.

<p>The inverse base-rate effect is the observation that on certain occasions people classify new objects as belonging to rare base-rate categories rather than common ones (e.g., D. L. Medin & S. M. Edelson, 1988). This finding is inconsistent with normative prescriptions of rationality, and provides an anomaly for current theories of human knowledge representation, such as the exemplar-based models of categorization, which predict a consistent use of base-rates (e.g., D. L. Medin & M. M. Schaffer, 1978). This thesis presents a novel explanation of the inverse base-rate effect. The proposal is that participants sometimes eliminate category options that are inconsistent with well-supported inference rules. These assumptions contrast with those by attentional theory (J. K. Kruschke, in press), according to which the inverse base-rate effect is the outcome of rapid attention shifts operating on cue-category associations. Study I, II, and III verified seven qualitative predictions derived from the eliminative inference idea. None of these phenomena can be explained by attentional theory. The most important of these findings were that elimination of well-known, common categories mediate the inverse base-rate effect rather than the strongest cue-category associations (Study I), that only participants with a rule-based mode of generalization exhibit the inverse base-rate effect (Study II), and that rapid attentional shifts per se do not accelerate learning, but rather decelerate it (Study III). In addition, Study I provided a quantitative implementation of the eliminative inference idea, ELMO, that demonstrated that this high-level reasoning process can produce the basic pattern of base-rate effects in the inverse base-rate design. Taken together, as an account of the inverse base-rate effect the empirical evidence of this thesis suggest that rule-based elimination is a powerful component of the inverse base-rate effect. But previous studies have indicated that attentional shifts affect the inverse base-rate effect, too. Therefore, a complete account of the inverse base-rate effect needs to integrate inductive and eliminative inferences operating on rule-based representations with attentional shifts. The Discussion of this thesis propose a number of suggestions for such integrative work. </p>

<p>Natural selection mediated by pollinators has influenced the evolution of floral diversity of the flowering plants (angiosperms). The scope of this thesis was to study: 1) phenotypic selection, 2) mating systems, and 3) floral shifts involved in plant speciation. Model plant species were <i>Platanthera bifolia</i> and <i>P. chlorantha</i> (Orchidaceae). These orchids are moth-pollinated, strictly co-sexual (bisexual flowers), and produce a spike that displays 10-20 white flowers.</p><p>I explored the influence of characters on plant fitness by using multiple linear regressions. Pollen removal (male fitness) and fruit set (female fitness) increased with more flowers per plant in three <i>P. bifolia</i> populations. There was selection towards longer spurs in a dry year when average spur length was shorter than in normal-wet years. Female function was sensitive to drought, which enabled an application of the male function hypothesis of floral evolution (Bateman's principle). The results show that selection may vary between populations, years, and sex-functions.</p><p>I examined inbreeding by estimating levels of geitonogamy (self-pollination between flowers of an individual) with an emasculation method in two <i>P. bifolia</i> populations. Geitonogamy did not vary with inflorescence size. Levels of geitonogamy was 20-40% in the smaller, but non-significant in the larger population. This may relate to lower number of possible mates and pollinator activity in the smaller population.</p><p><i>Platanthera bifolia</i> exhibits the ancestral character state of tongue-attachment of pollinia on the pollinator. Its close relative <i>P. chlorantha</i> attaches its pollinia onto the pollinator's eyes. To explore the mechanism of a floral shift, pollination efficiency and speed was compared between the two species. The results showed no differences in pollination efficiency, but <i>P. chlorantha</i> had faster pollen export and import. Efficiency of pollination in terms of speed may cause floral shifts, and thus speciation.</p>

The correlation between NMR chemical shifts of interstitial atoms and electronic structures of boron- and carbon-centered hexazirconium halide clusters was investigated by density functional theory (DFT) calculation. The influences of bridging halide and terminal ligand variations on electronic structure were examined respectively. Inverse proportionality was found between the chemical shifts and the calculated energy gaps between two Kohn-Sham orbitals of t1u symmetry, which arose from the bonding and antibonding interaction between the zirconium cage bonding orbitals and the interstitial 2p orbitals. Chemical shielding properties of the interstitial atoms were calculated with Gauge Including Atomic Orbital (GIAO) method. Stepwise ligand substitution of terminal chlorides on [(Zr6CCl12)Cl6]4-cluster by tri(n-butyl)-phosphine oxide (Bu3PO) was conducted with the aid of TlPF6. Composition of the reaction mixtures was analyzed by use of both 13C and 31P NMR. A preliminary scheme for synthesis and separation of [(Zr6CCl12)Cl6-x(Bu3PO)x]x-4 (x = 3 ?? 5) mixture based on solubility difference was reevaluated. Three 1,10-phenanthroline based bidentate ligands, namely, 2,9-Bis(diphenyl-phosphinyl)-1,10-phenanthroline, 2,9-Bis(diethoxyphosphoryl)-1,10-phenanthroline, and 2,9-Bis(di-n-butoxyphosphoryl)-1,10-phenantholine, were synthesized for bridge-chelating the hexazirconium clusters. Coordination chemistry of these ligands with the [Zr6BCl12] and [Zr6CCl12] clusters was subject to preliminary investigation.

The inverse base-rate effect is the observation that on certain occasions people classify new objects as belonging to rare base-rate categories rather than common ones (e.g., D. L. Medin &amp; S. M. Edelson, 1988). This finding is inconsistent with normative prescriptions of rationality, and provides an anomaly for current theories of human knowledge representation, such as the exemplar-based models of categorization, which predict a consistent use of base-rates (e.g., D. L. Medin &amp; M. M. Schaffer, 1978). This thesis presents a novel explanation of the inverse base-rate effect. The proposal is that participants sometimes eliminate category options that are inconsistent with well-supported inference rules. These assumptions contrast with those by attentional theory (J. K. Kruschke, in press), according to which the inverse base-rate effect is the outcome of rapid attention shifts operating on cue-category associations. Study I, II, and III verified seven qualitative predictions derived from the eliminative inference idea. None of these phenomena can be explained by attentional theory. The most important of these findings were that elimination of well-known, common categories mediate the inverse base-rate effect rather than the strongest cue-category associations (Study I), that only participants with a rule-based mode of generalization exhibit the inverse base-rate effect (Study II), and that rapid attentional shifts per se do not accelerate learning, but rather decelerate it (Study III). In addition, Study I provided a quantitative implementation of the eliminative inference idea, ELMO, that demonstrated that this high-level reasoning process can produce the basic pattern of base-rate effects in the inverse base-rate design. Taken together, as an account of the inverse base-rate effect the empirical evidence of this thesis suggest that rule-based elimination is a powerful component of the inverse base-rate effect. But previous studies have indicated that attentional shifts affect the inverse base-rate effect, too. Therefore, a complete account of the inverse base-rate effect needs to integrate inductive and eliminative inferences operating on rule-based representations with attentional shifts. The Discussion of this thesis propose a number of suggestions for such integrative work.

Natural selection mediated by pollinators has influenced the evolution of floral diversity of the flowering plants (angiosperms). The scope of this thesis was to study: 1) phenotypic selection, 2) mating systems, and 3) floral shifts involved in plant speciation. Model plant species were Platanthera bifolia and P. chlorantha (Orchidaceae). These orchids are moth-pollinated, strictly co-sexual (bisexual flowers), and produce a spike that displays 10-20 white flowers. I explored the influence of characters on plant fitness by using multiple linear regressions. Pollen removal (male fitness) and fruit set (female fitness) increased with more flowers per plant in three P. bifolia populations. There was selection towards longer spurs in a dry year when average spur length was shorter than in normal-wet years. Female function was sensitive to drought, which enabled an application of the male function hypothesis of floral evolution (Bateman's principle). The results show that selection may vary between populations, years, and sex-functions. I examined inbreeding by estimating levels of geitonogamy (self-pollination between flowers of an individual) with an emasculation method in two P. bifolia populations. Geitonogamy did not vary with inflorescence size. Levels of geitonogamy was 20-40% in the smaller, but non-significant in the larger population. This may relate to lower number of possible mates and pollinator activity in the smaller population. Platanthera bifolia exhibits the ancestral character state of tongue-attachment of pollinia on the pollinator. Its close relative P. chlorantha attaches its pollinia onto the pollinator's eyes. To explore the mechanism of a floral shift, pollination efficiency and speed was compared between the two species. The results showed no differences in pollination efficiency, but P. chlorantha had faster pollen export and import. Efficiency of pollination in terms of speed may cause floral shifts, and thus speciation.

It is increasingly recognized that individuals of the same species differ from each other and influence and respond to their environment in unique ways. This thesis deals with size variation among individuals that not only are of the same species but also of similar age. Such variation may develop even when individuals are born in the same environment, i.e. within a cohort. I have studied the sources and consequences of variation within and among cohorts from egg through early ontogeny using young-of-the-year (YOY) perch (Perca fluviatilis) as study organism. In agreement with predictions based on model results only taking exploitative interactions among individuals into account, I found that the broader the initial size distributions were, the more did the degree of size variation among individuals decrease over time. Still, with initially small size variation among individuals, in several experiments also size divergence was observed. Furthermore, size variation among individuals increased more under high compared to at low densities. Increased size variation over time may be explained by size-dependent diet shifts allowing for initially larger individuals to make an early diet shift when the first resource becomes limiting. However, as size divergence also was observed in situations with only shared resources available, it can be concluded that diet shifts are not a prerequisite for size divergence in young animal cohorts. Hence, I also suggest that mechanisms not related to competition for limiting resources, such as genetic variation, stochasticity and behavioural traits must be taken into account, especially when initial size differences are small. The importance of considering size variation among individuals within cohorts was demonstrated in a study of winter mortality in YOY perch cohorts. A large individual size in autumn was shown to increase overwinter survival within cohorts. However, late summer growth rather than average body size reached in autumn explained variation in overwinter survival between cohorts. Higher accumulation to lipid reserves and accordingly lower mortality over winter was observed in years with high growth rates late in the season. In another study I showed that apparent patterns of density-dependent growth can emerge among larval fish, but rather than a result of density-dependent resource limitation this was due to variation in size-selective predation pressure. Individuals in the right end of the size distributions grew in to a high predation pressure from cannibalistic perch when cannibal density was high, coinciding with high larval perch densities. Finally, as substantial size variation among individuals can develop within cohorts, also intra-cohort cannibalism can occur. Using a physiologically structured population model it was shown that the development of size bimodality within cohorts as a result of intra-cohort cannibalism is critically dependent on long hatching periods, high victim densities and density-dependent feedbacks on shared resources. / Det faktum att individer som tillhör samma art skiljer sig från varandra och påverkar och påverkas av sin omgivande miljö på ett unikt sätt tillskrivs allt större betydelse inom ekologin. Den här avhandlingen handlar framför allt om storleksvariation mellan individer som förutom att tillhöra samma art dessutom tillhör samma årsklass. Sådan storleksvariation kan till och med utvecklas mellan individer som föds och växer upp i samma miljö (inom en kohort). Jag har studerat orsaker bakom och konsekvenser av variation inom och mellan kohorter. Som studieorganism har jag använt mig av årsyngel av abborre (Perca fluviatilis). I överensstämmelse med förutsägelser baserade på en modell som enbart tar hänsyn till konkurrens om en gemensam resurs visade det sig såväl i ett dammexperiment som i en naturlig sjö att ju bredare den initiala storleksfördelningen var desto mer minskade graden av variation i kroppsstorlek mellan individer över tid. Å andra sidan, när den initiala variationen var relativt liten observerades i flera oberoende experiment även storleksdivergens över tid mellan individer. Variationen i storlek ökade särskilt i miljöer med höga tätheter av konsumenter (abborrar). För att förstå de bakomliggande mekanismerna av sådana täthetseffekter måste man ta hänsyn till den återkoppling som sker mellan antalet konsumenter och mängden resurser. Ökad storleksvariation över tid skulle kunna förklaras med storleksberoende dietskiften som tillåter individer med en initial storleksfördel att genomgå ett tidigt dietskifte samtidigt som tillgången av den första resursen begränsar övriga individers tillväxt. Eftersom storleksdivergens även observerades i situationer där enbart en delad resurs var tillgänglig kan man dock dra slutsatsen att dietskiften inte är en förutsättning för storleksdivergens inom kohorter. Jag föreslår därför också att mekanismer som inte är relaterade till konkurrens om en begränsad resurs, såsom inneboende variation mellan individer och variation i beteendemönster bör beaktas för att förklara uppkomsten av storleksvariation, speciellt i de fall då den initiala variationen är liten. De resultat som presenteras visar på betydelsen av att ta hänsyn till storleksvariation mellan individer. Storlek efter den första tillväxtsäsongen var viktig för att förklara vilka individer inom en kohort av årsyngel som överlever sin första vinter. För att förklara variation i vinteröverlevnad mellan kohorter (mellan år och sjöar) var däremot hög tillväxt sent på säsongen (oberoende av medelstorlek på hösten) avgörande. Högre ackumulering av fettreserver och lägre mortalitet inom kohorter av årsyngel under vintern observerades under år med hög tillväxt under den senare delen av tillväxtsäsongen. I en annan studie visade jag att mönster som tyder på täthetsberoende tillväxt kan uppkomma hos fiskyngel men att detta fenomen snarare än täthetsberoende resursbegränsning förklaras av variation i storleksberoende predationstryck. De större individerna inom kohorterna växte in i ett högt predationstryck från kannibalistiska abborrar när tätheten av kannibaler var hög, något som samkorrelerade med höga tätheter av yngel. Slutligen, då en hög grad av storleksvariation mellan individer kan utvecklas inom kohorter är även kannibalism mellan individer inom en kohort möjligt. Genom att använda mig av en så kallad fysiologiskt strukturerad populationsmodell kunde jag visa att divergerande tillväxtkurvor mellan kannibaler och deras byten (vilket resulterar i storleksbimodalitet) som ett resultat av kannibalism inom kohorter är beroende av den tid det tar för ynglen att kläcka ut, antalet bytesfiskar per kannibal samt den återkoppling som finns mellan konsumenterna och deras gemensamma resurs (djurplankton).

Temperature and precipitation are the most important indicators of climate change. Especially for the basins fed by snow, the shifts of melting to earlier times, affects the streamflow. Increase in temperature causes to shifts of melting of snow to shift to earlier times so that hydrologic regime of the river system changes, and leads to changes in climatic conditions of the region. In this study the shifts of snow melting times are analyzed for the selected 15 streamflow stations located in Euphrates, Tigris, Aras, and &Ccedil / oruh basins in Eastern Anatolia of Turkey along with period from 1970 to 2010. The shifts in snowmelt runoff are determined by Center Time (CT) method. Meteorological stations representing the stream gauge stations regarding the basin characteristics are also selected to be used in the analyses. In order to relate CT shifts to temperature and precipitation changes, trend analysis are applied to temperature, precipitation and streamflow data. In addition to these, days with daily average temperature less than freezing and wet days below freezing until CT for each station pair between stream gauge and meteorological stations and each year are also analyzed. These days till CT within a year for each station pair can be indirectly linked to snowy days and accumulated snow amount. Complete analyses show significant warming at each station in the region and no important trends in annual precipitation. However at a few stations meaningful seasonal changes in precipitation are observed. Regional warming and associated changes in precipitation and snowmelt runoff cause significant shifts to earlier times of snowmelt runoff. In the region eight out of fifteen stream gauge stations in Euphrates, Tigris and Aras basins showed significant time shifts according to statistical trend tests.