920 resultados para Expectations hypothesis of term struscture of interest rates
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Extremely preterm infants commonly show brain injury with long-term structural and functional consequences. Three-day-old (P3) rat pups share some similarities in terms of cerebral development with the very preterm infant (born at 24-28 weeks of gestation). The aim of this study was to assess longitudinally the cerebral structural and metabolic changes resulting from a moderate neonatal hypoxic ischemic injury in the P3 rat pup using high-field (9.4 T) MRI and localized (1) H magnetic resonance spectroscopy techniques. The rats were scanned longitudinally at P3, P4, P11, and P25. Volumetric measurements showed that the percentage of cortical loss in the long term correlated with size of damage 6 h after hypoxia-ischemia, male pups being more affected than female. The neurochemical profiles revealed an acute decrease of most of metabolite concentrations and an increase in lactate 24 h after hypoxia-ischemia, followed by a recovery phase leading to minor metabolic changes at P25 in spite of an abnormal brain development. Further, the increase of lactate concentration at P4 correlated with the cortical loss at P25, giving insight into the early prediction of long-term cerebral alterations following a moderate hypoxia-ischemia insult that could be of interest in clinical practice.
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We investigate the effects of the financial crisis on the stationarity of real interest rates in the Euro Area. We use a new unit root test developed by Peseran et al. (2013) that allows for multiple unobserved factors in a panel set up. Our results suggest that while short-term and long-term real interest rates were stationary before the financial crisis, they became nonstationary during the crisis period likely due to persistent risk that characterized financial markets during that time. JEL codes: E43, C23. Keywords: Real interest rates, Euro Area, financial crisis, panel unit root tests, cross-sectional dependence.
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Rsum Scientific:Ptrologie et Gochimie du Complexe Plutonique de Chaltn et les consquences pour l'volution magmatique et tectonique du Andes du Sud (Patagonia) pendant le MiocneLe sujet de cette thse est le Complexe Plutonique de Chaltn (CHPC), situ la frontire entre le Chili et l'Argentine, en Patagonie (4915'S). Ce complexe s'est mis en place au dbut du Miocne, dans un contexte de changements tectoniques importants. La gomtrie et la vitesse de migration des plaques en Patagonie a t modifie suite l'ouverture de la plaque Farallon il y a 25Ma (Pardo-Casas and Molnar 1987) et la subduction de la ride active du Chili sous la plaque sud-amricaine il y a 14Ma (Cande and Leslie 1986). Les effets de cette reconfiguration tectonique sur la morphologie et le magmatisme de la plaque suprieure sont encore sujets discussion. Dans ce contexte, un groupe d'intrusions miocnes - telle que le CHPC - est particulirement intriguant, car en position transitionnelle entre le batholithe patagonien et l'arc volcanique cnozoque et rcent l'ouest, et les laves de plateau de Patagonie l'est (Fig. 1). A cause de leur position tectonique transitoire, ces plutons isols hors du batholithe reprsentent un endroit cl pour comprendre les interactions entre la tectonique large chelle et le magmatisme en Patagonie. Ici, je prsente de nouvelles donnes de terrain, petrologiques, gochimiques et gochronologiques dans le but de caractriser la nature du CHPC, qui tait largement inconnu avant cette tude, dans le but de tester l'hypothse de migration de l'arc et erosion par subduction.Les rsultats de l'investigation gochimique (chapitre 2) montrent que le CHPC n'est qu'un exemple parmi les plutons isols d'arrire arc ave une composition calco-alcaline caractristique, c--d une signature d'arc. La plupart de ces plutons isols ont une composition alcaline. Le CHPC, contrairement, a une signature calco-alcaline avec Κ intermdiaire, tel que le batholithe patagonien et la plupart des roches volcaniques quaternaires lies l'arc le long des Andes.De nouvelles donnes gochronologiques U-Pb de haute prcision sur des zircons, acquis par TIMS, sur le CHPC donnent des ges entre 17.0 et 16.4Ma. Les ges absolus sont en accord avec la squence intrusive dduite des relations de terrain (chapitre 1). Ces donnes sont les premires contraintes d'ge U-Pb sur le CHPC. Elles montrent clairement que l'histoire magmatique du CHPC n'a pas de lien direct avec la subduction de la ride cette latitude (Cande and Leslie 1986), car le complexe est au moins 6Ma plus ancien.Une comparaison en profondeur avec les autres intrusions d'ge Miocne en Patagonie rvlent - pour la premire fois - une volution temporelle intressante. Il y a une tendance E-W distincte au magmatisme calco-alcalin entre 20-16Ma avec une diminution de l'ge vers l'est - le CHPC est l'expression la plus orientale de cette tendance. Je suggre que la relation espace-temps reflte une migration vers l'est (vers le continent) de l'arc magmatique. Je propose que le facteur principal contrlant cette migration est la subduction rapide suite la reconfiguration de la vitesse des plaques tectoniques aprs l'ouverture la plaque Farallon ( ~26Ma) qui rsulterait en une dformation importante ainsi qu' des taux levs d'rosion dans la fosse de subduction.Les rapports d'isotopes radiogniques (Pb, Sr, Nd) levs, une signature 6018 basse et un rapport Th/La lev sont des paramtres distinctifs pour les roches mafiques du CHPC. Le modle isotopique prsent (chapitre 2) suggre que cette signature reflte une contamination de la source, dans le coin de manteau, plutt qu'une contamination crustale. La signature des lments en trace du CHPC indiquent que le coin de manteau a t contamin par des composs terrignes, le plus vraisemblablement par des sdiments palozoques.Les travaux de terrain, la ptrographie et la gothermobaromtrie ont t utiliss dans le but de comprendre l'histoire interne du CHPC (chapitre 3). Ces donnes suggrent deux niveaux distincts de cristallisation : l'un dans la crote moyenne (6 4.5kbar) et l'autre un niveau peu profond (3.5 2kbar). La modlisation isotopique AFC de la contamination crustale indique des taux variables d'assimilation, qui ne sont pas corrls avec le degr de diffrenciation. Cela suggre que diffrents volumes de magma se sont diffrencis en profondeur, de faon indpendante. Cela implique que le CHPC se serait forms en plusieurs puises de magmas provenant d'au moins trois sources diffrentes. Les textures des granodiorites et des granites indiquent des teneurs leves en cristaux avant la mise en place et, par consquent, des tempratures d'emplacement faibles. Les observations de terrain montrent que les roches mafiques sont dformes, alors que ce n'est pas le cas pour les granodiorites et granites (plus jeunes). La dformation des roches mafiques est encore sujet de recherche, afin de savoir si elle est lie la dformation rgionale en rgime compressif ou l'emplacement lui-mme. Cependant, la mise en place de grand volume de magma felsique riche en cristaux suggre un rgime d'extension.Scientific Abstract:Petrology and chemistry of the Chaltn Plutonic Complex and implications on the magmatic and tectonic evolution of the Southernmost Andes (Patagonia) during the MioceneThe subject of this thesis is the Chaltn Plutonic Complex (CHPC) located at the frontier between Chile and Argentina in Patagonia (at 49 15 'Southern latitude). This complex intruded during early Miocene in a context of major tectonics changes. The plate geometry of Patagonia has been modified by changes in the plate motions after the break up of the Faralln plate at 25Ma (Pardo-Casas and Molnar 1987) and by the subduction of the Chile spreading Ridge beneath South-America at 14 Ma (Cande and Leslie 1986). The effects of this tectonic setting on the morphology and the magmatism of the overriding plate are a matter of on-going discussion. Particularly intriguing in this context is a group of isolated Miocene intrusions - like the CHPC - which are located in a transitional position between the Patagonian Batholith and the Cenozoic and Recent volcanic arc in the West, and the Patagonian plateau lavas in the East (Fig. 1). Due to their transient tectonic position these isolated plutons outside the batholith represent a key to understanding the interaction between global-scale tectonics and magmatism in Patagonia. Here, I present new field, penological, geochemical and geochronological data to characterize the nature of the CHPC, which was largely unknown before this study, in order to test the hypothesis of time- transgressive magmatism.The results of the geochemical investigation (Chapter 2) show that the CHPC is only one among these isolated back-arc plutons with a characteristic calc-alkaline composition, i.e. arc signature. Most of these isolated intrusives have an alkaline character. The CHPC, in contrast, has a medium Κ calc-alkaline signature, like the Patagonian batholith and most of the Quaternary arc-related volcanic rocks along the Andes.New high precision TIMS U-Pb zircon dating of the CHPC yield ages between 17.0 to 16.4 Ma. The absolute ages support the sequence of intrusion relations established in the field (Chapter 1). These data are the first U-Pb age constraints on the CHPC, and clearly show that the magmatic history of CHPC has no direct link to the subduction of the ridge, since this complex is at least 6 Ma older than the time of collision of the Chile ridge at this latitude (Cande and Leslie 1986).An in-depth comparison with other intrusion of Miocene age in Patagonia reveals - for the first time - an interesting temporal pattern. There is a distinct E-W trend of calc-alkaline magmatism between 20-16 Ma with the younging of ages in the East - the CHPC is the easternmost expression of this trend. I suggest that this time-space relation reflects an eastward (landward) migration of the magmatic arc. I propose that main factor controlling this migration is the fast rates of subduction after the major reconfigurations of the plate tectonic motions after the break up of the Faralln Plate (at -26 ) resulting in strong deformation and high rates of subduction erosion.High radiogenic isotope ratios (Pb, Sr, Nd) ratios, low 5018 signature and high Th/La ratios in mafic rocks are distinctive features of the CHPC. The presented isotopic models (Chapter 2) suggest that this signature reflects source contamination of the mantle wedge rather than crustal contamination. The trace element signature of the CHPC indicates that the mantle wedge was contaminated with a terrigenous component, most likely from Paleozoic sediments.Fieldwork, petrography and geothermobarometry were used to further unravel the internal history of the CHPC (Chapter 3). These data suggest two main levels of crystallization: one a mid crustal levels (6 to 4.5 kbar) and other a shallow level (3.5 to 2 kbar). Isotopic AFC modeling of crustal contamination indicate variable rates of assimilation, which are not correlated with the degree of differentiation. This suggests that different batches of magma differentiate independently at depths. This implies that the CHPC would have formed by several pulses of magmas from at least 3 different sources. Textures of granodiorites and granites indicate a high content of crystals previous to the emplacement and consequently low emplacement temperatures. Field observations show that the mafic rocks are deformed, whereas the (younger) granodiorites and granites are not. It is still subject of investigation whether the deformation of the mafic rocks is related to regional deformation during a compressional regime or to the emplacement it self. However, the emplacement of huge amount of crystal rich felsic magmas suggests an extensional regime.Rsum Grand PublicPtrologie et Gochimie du Complexe Plutonique de Chaltn et les consquences pour l'volution magmatique et tectonique du Andes du Sud (Patagonia) pendant le MiocneLe Complexe Plutonique de Chaltn (CHPC) est un massif montagneux situ 49S la frontire entre le Chili et l'Argentine, en Patagonie (rgion la plus au sud de l'Amrique du Sud). Il est compos de montagnes qui peuvent atteindre plus de 3000 mtres d'altitude, telles que le Cerro Fitz Roy (3400m) et le Cerro Torre (3100m). Ces montagnes sont composes de roches plutoniques, c.--d. des magmas qui se sont refroidis et ont cristalliss sous la surface terrestre.La composition chimique de ces roches montre que les magmas, qui ont form ce complexe plutonique, font partie d'un volcanisme d'arc. Celui-ci se forme lorsqu'une plaque ocanique plonge sous une plaque continentale. Les gologues appellent ce processus subduction . Dans un tel scnario, le manteau terrestre, qui se fait prendre entre ces deux plaques, fond pour former ainsi du magma. Ce magma remonte travers la plaque continentale vers la surface. Si celui-ci atteint la surface, il forme les roches volcaniques, comme par exemple des laves. S'il n'atteint pas la surface, le magma se refroidit pour former finalement les roches plutoniques.Le long de la marge ouest d'Amrique du Sud, la plaque Nazca - qui se situe au sud-est de la plaque ocanique pacifique - passe en dessous de la plaque d'Amrique du Sud. La bordure ouest du sud de la plaque sud-amricaine a galement t affecte par d'autres processus tectoniques, tels que des changements dramatiques dans les dplacements de plaques (il y a 25Ma) et la collision de la ride du Chili (depuis 15 Ma jusqu' aujourd'hui). Ces caractristiques tectoniques et magmatiques font de cette rgion un haut lieu pour les gologues. La plaque Nazca, s'est forme suite l'ouverture d'une plaque ocanique plus ancienne, il y a 25Ma. Cette ouverture est lie aux vitesses de subduction les plus rapides jamais connues. La ride du Chili est l'endroit o le sol de l'Ocan Pacifique s'ouvre, formant deux plaques ocaniques : les plaques Nazca et Antarctique. La ride du Chili subducte sous la plaque sud-amricaine depuis 15Ma, en association avec la formation de grands volumes de magma ainsi que des changements morphologiques importants. La question de savoir lequel de ces changements tectoniques globaux affecte la gologie et la gographie de Patagonie a t, et est encore, discute pendant de nombreuses annes. De nombreux chercheurs suggrent que la plupart des caractristiques morphologiques et magmatiques en Patagonie sont lis la subduction de la ride du Chili, mais cette suggestion est encore dbattue comme le montre notre tude.Le batholithe de Patagonie du sud (SPB) est un norme massif compos de roches plutoniques et il s'tend tout au long de la cte ouest de Patagonie (au sud de 47S). Ces roches correspondent certainement aux racines d'un ancien arc volcanique, qui a t soulev et rod. Le CHPC, ainsi que d'autres petites intrusions dans la rgion, se situe dans une position exotique, 100km l'est du SPB. Certains chercheurs suggrent que ces intrusions pourraient tre lies la subduction de la ride du Chili.Afin de dbattre de cette problmatique, nous avons utilis diffrentes mthodes gochronologiques pour dterminer l'ge du CHPC et le comparer (a) l'ge des roches intrusives similaires du SPB et (b) l'ge de la collision de la ride du Chili. Dans ce travail, nous prouvons que le CHPC s'est form au moins 7Ma avant la collision avec la ride du Chili. Sur la base des ges du CHPC et de la composition chimique de ses roches et minraux, nous proposons que le CHPC fait partie d'un arc volcanique ancien. La migration de l'arc volcanique plus profondment dans le continent rsulte de la grande vitesse de subduction entre 25 et lOMa. Des caractristiques videntes pour un tel processus - telles qu'une dformation importante et une vitesse d'rosion leve - peuvent tre rencontres tout au long de la bordure ouest de l'Amrique du sud.
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Extensive theoretical and experimental work on the neuronal correlates of visual attention raises two hypotheses about the underlying mechanisms. The first hypothesis, named biased competition, originates from experimental single-cell recordings that have shown that attention upmodulates the firing rates of the neurons encoding the attended features and downregulates the firing rates of the neurons encoding the unattended features. Furthermore, attentional modulation of firing rates increases along the visual pathway. The other, newer hypothesis assigns synchronization a crucial role in the attentional process. It stems from experiments that have shown that attention modulates gamma-frequency synchronization. In this paper, we study the coexistence of the two phenomena using a theoretical framework. We find that the two effects can vary independently of each other and across layers. Therefore, the two phenomena are not concomitant. However, we show that there is an advantage in the processing of information if rate modulation is accompanied by gamma modulation, namely that reaction times are shorter, implying behavioral relevance for gamma synchronization.
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We test whether outside experts have information not available to insiders by usingthe voting record of the Bank of England's Monetary Policy Committee. Memberswith more private information should vote more often against conventional wisdom,which we measure as the average belief of market economists about future interest rates. We find evidence that external members indeed have information notavailable to internals, but also use a quasi-natural experiment to show they mayexaggerate their expertise to obtain reappointment. This implies that an optimalcommittee, even outside monetary policy, should potentially include outsiders, butneeds to manage career concerns.
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Rsum Les changements climatiques du Quaternaire ont eu une influence majeure sur la distribution et l'volution des biota septentrionaux. Les Alpes offrent un cadre spatio-temporel bien tudi pour comprendre la ractivit de la flore et le potentiel d'adaptation d'une espce vgtale face aux changements climatiques. Certaines hypothses postulent une diversification des espces en raison de la disparition complte de la flore des Alpes et d'un isolement important des espces dans des refuges mridionaux durant les dernires glaciations (Tabula Rasa). Une autre hypothse stipule le maintien de poches de rsistance pour la vgtation au coeur des Alpes (Nunataks). Comme de nombreuses espces vgtales prsentant un grand succs cologique semblent avoir ragi aux glaciations par la multiplication de leur gnome (autopolyplodie), leur tude en milieu naturel devrait permettre de comprendre les avantages inhrents la polyplodie. Biscutella laevigata est un modle emblmatique de biogographie historique, diverses tudes ayant montr que des populations diplodes sont actuellement isoles dans les zones restes dglaces durant le dernier maximum glaciaire, alors que des ttraplodes ont recolonis l'ensemble des zones alpines mises nu par le retrait des glaciers. Si le contexte priglaciaire semble avoir favoris ce jeune complexe autopolyplode, les circonstances et les avantages de cette mutation gnomique ne sont pas encore clairs. Y a-t-il eu de multiples vnements de polyplodisation ? Dans quelle mesure affecte(nt)il(s) la diversit gntique et le potentiel volutif des polyplodes ? Les polyplodes ont-ils une grande flexibilit gnomique, favorisant une radiation adaptative, ou doivent-ils leur succs une grande plasticit cologique ? Cette tude aborde ces questions diffrentes chelles spatiales et temporelles. L'chelle rgionale des Alpes occidentales permet d'aborder les facteurs distaux (aspects historiques), alors que l'chelle locale cherche apprhender les facteurs proximaux (mcanismes volutifs). Dans les Alpes occidentales, des populations ont t densment chantillonnes et tudies grce (1) leur cytotype, (2) leur appartenance taxonomique, (3) leur habitat et (4) des marqueurs molculaires de l'ADN chloroplastique, en vue d'tablir leurs affinits volutives. l'chelle locale, deux systmes de population ont t tudis : l'un o les populations persistent en priphrie de l'aire de distribution et l'autre au niveau du front actif de colonisation, en marge altitudinale. Les rsultats l'chelle des Alpes occidentales rvlent les sites d'intrt (refuges glaciaires, principales barrires et voies de recolonisation) pour une espce reprsentative des pelouses alpines, ainsi que pour la biodiversit rgionale. Les Pralpes ont jou un rle important dans le maintien de populations proximit immdiate des Alpes centrales et dans l'volution du taxon, voire de la vgtation. Il est aussi dmontr que l'poque glaciaire a favoris l'autopolyplodie polytopique et la recolonisation des Alpes occidentales par des lignes distinctes qui s'hybrident au centre des Alpes, influenant fortement leur diversit gntique et leur potentiel volutif. L'analyse de populations locales en situations contrastes l'aide de marqueurs AFLP montre qu'au sein d'une ligne prsentant une grande expansion, la diversit gntique est faonne par des forces volutives diffrentes selon le contexte cologique et historique. Les populations persistant prsentent une dispersion des gnes restreinte, engendrant une diversit gntique assez faible, mais semblent adaptes aux conditions locales de l'environnement. l'inverse, les populations colonisant la marge altitudinale sont influences par les effets de fondation conjugus une importante dispersion des gnes et, si ces processus impliquent une grande diversit gntique, ils engendrent une rpartition alatoire des gnotypes dans l'environnement. Les autopolyplodes apparaissent ainsi comme capables de persister face aux changements climatiques grce certaines facults d'adaptation locale et de grandes capacits maintenir une importante diversit gntique lors de la recolonisation post-glaciaire. Summary The extreme climate changes of the Quaternary have had a major influence on species distribution and evolution. The European Alps offer a great framework to investigate flora reactivity and the adaptive potential of species under changing climate. Some hypotheses postulate diversification due to vegetation removal and important isolation in southern refugia (Tabula Rasa), while others explain phylogeographic patterns by the survival of species in favourable Nunataks within the Alps. Since numerous species have successfully reacted to past climate changes by genome multiplication (autopolyploidy), studies of such taxa in natural conditions is likely to explain the ecological success and the advantages of autopolyploidy. Early cytogeographical surveys of Biscutella laevigata have shed light on the links between autopolyploidy and glaciations by indicating that diploids are now spatially isolated in never-glaciated areas, while autotetraploids have recolonised the zones covered by glaciers- during the last glacial maximum. A periglacial context apparently favoured this young autopolyploid complex but the circumstances and the advantages of this genomic mutation remain unclear. What is the glacial history of the B. laevigata autopolyploid complex? Are there multiple events of polyploidisation? To what extent do they affect the genetic diversity and the evolutionary potential of polyploids? Is recolonisation associated with adaptive processes? How does long-term persistence affect genetic diversity? The present study addresses these questions at different spatiotemporal scales. A regional survey at the Western Alps-scale tackles distal factors (evolutionary history), while local-scale studies explore proximal factors (evolutionary mechanisms). In the Western Alps, populations have been densely sampled and studied from the (1) cytotypic, (2) morphotaxonomic, (3) habitat point of views, as well as (4) plastid DNA molecular markers, in order to infer their relationships and establish the maternal lineages phylogeography. At the local scale, populations persisting at the rear edge and populations recolonising the attitudinal margin at the leading edge have been studied by AFLPs to show how genetic diversity is shaped by different evolutionary forces across the species range. The results at the regional scale document the glacial history of a widespread species, representative of alpine meadows, in a regional area of main interest (glacial refugia, main barriers and recolonisation routes) and points out to sites of interest for regional biodiversity. The external Alps have played a major role in the maintenance of populations near the central Alps during the Last Glacial Maximum and influenced the evolution of the species, and of vegetation. Polytopic autopolyploidy in different biogeographic districts is also demonstrated. The species has had an important and rapid radiation because recolonisation took place from different refugia. The subsequent recolonisation of the Western Alps was achieved by independent lineages that are presently admixing in the central Alps. The role of the Pennic summit line is underlined as a great barrier that was permeable only through certain favourable high-altitude passes. The central Alps are thus viewed as an important crossroad where genomes with different evolutionary histories are meeting and admixing. The AFLP analysis and comparison of local populations growing in contrasted ecological and historical situations indicate that populations persisting in the external Alps present restricted gene dispersal and low genetic diversity but seem in equilibrium with their environment. On the contrary, populations colonising the attitudinal margin are mainly influenced by founder effects together with great gene dispersal and genotypes have a nearly random distribution, suggesting that recolonisation is not associated with adaptive processes. Autopolyploids that locally persist against climate changes thus seem to present adaptive ability, while those that actively recolonise the Alps are successful because of their great capacity to maintain a high genetic diversity against founder effects during recolonisation.
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In this paper we argue that inventory models are probably not usefulmodels of household money demand because the majority of households does nothold any interest bearing assets. The relevant decision for most people is notthe fraction of assets to be held in interest bearing form, but whether to holdany of such assets at all. The implications of this realization are interesting and important. We find that(a) the elasticity of money demand is very small when the interest rate is small,(b) the probability that a household holds any amount of interest bearing assetsis positively related to the level of financial assets, and (c) the cost ofadopting financial technologies is positively related to age and negatively relatedto the level of education. Unlike the traditional methods of money demand estimation, our methodology allowsfor the estimation of the interest--elasticity at low values of the nominalinterest rate. The finding that the elasticity is very small for interest ratesbelow 5 percent suggests that the welfare costs of inflation are small. At interest rates of 6 percent, the elasticity is close to 0.5. We find thatroughly one half of this elasticity can be attributed to the Baumol--Tobin orintensive margin and half of it can be attributed to the new adopters or extensivemargin. The intensive margin is less important at lower interest rates and moreimportant at higher interest rates.
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This paper analyses the empirical interdependences among assetreturns, real activity and inflation from a multicountry and internationalpoint of view. We find that nominal stock returns are significantly relatedto inflation only in the US, that the US term structure of interest ratespredicts both domestic and foreign inflation rates while foreign termstructures do not have this predictive power and that innovations in inflationand exchange rates induce insignificant responses of real and financialvariables. An interpretation of the dynamics and some policy implicationsof the results are provided.
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Self-reported home values are widely used as a measure of housing wealth by researchers employing a variety of data sets and studying a number of different individual and household level decisions. The accuracy of this measure is an open empirical question, and requires some type of market assessment of the values reported. In this research, we study the predictive power of self-reported housing wealth when estimating sales prices utilizing the Health and Retirement Study. We find that homeowners, on average, overestimate the value of their properties by between 5% and 10%. More importantly, we are the first to document a strong correlation between accuracy and the economic conditions at the time of the purchase of the property (measured by the prevalent interest rate, the growth of household income, and the growth of median housing prices). While most individuals overestimate the value of their properties, those who bought during more difficult economic times tend to be more accurate, and in some cases even underestimate the value of their house. These results establish a surprisingly strong, likely permanent, and in many cases long-lived, effect of the initial conditions surrounding the purchases of properties, on how individuals value them. This cyclicality of the overestimation of house prices can provide some explanations for the difficulties currently faced by many homeowners, who were expecting large appreciations in home value to rescue them in case of increases in interest rates which could jeopardize their ability to live up to their financial commitments.
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The paper defines concepts of real wealth and saving which take into account the intertemporal index number problem that results from changing interest rates. Unlike conventional measures of real wealth, which are based on the market value of assets and ignore the index number problem, the new measure correctly reflects the changes in the welfare of households over time. An empirically operational approximation to the theoretical measure is provided and applied to US data. A major empirical finding is that US real financial wealth increased strongly in the 1980s, much more than is revealed by the market value of assets.
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We show that the Heston volatility or equivalently the Cox-Ingersoll-Ross process is Malliavin differentiable and give an explicit expression for the derivative. This result assures the applicability of Malliavin calculus in the framework of the Heston stochastic volatility model and the Cox-Ingersoll-Ross model for interest rates.
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We combine existing balance sheet and stock market data with two new datasets to studywhether, how much, and why bank lending to firms matters for the transmission of monetarypolicy. The first new dataset enables us to quantify the bank dependence of firms precisely,as the ratio of bank debt to total assets. We show that a two standard deviation increase inthe bank dependence of a firm makes its stock price about 25% more responsive to monetarypolicy shocks. We explore the channels through which this effect occurs, and find that thestock prices of bank-dependent firms that borrow from financially weaker banks display astronger sensitivity to monetary policy shocks. This finding is consistent with the banklending channel, a theory according to which the strength of bank balance sheets mattersfor monetary policy transmission. We construct a new database of hedging activities andshow that the stock prices of bank-dependent firms that hedge against interest rate riskdisplay a lower sensitivity to monetary policy shocks. This finding is consistent with aninterest rate pass-through channel that operates via the direct transmission of policy ratesto lending rates associated with the widespread use of floating-rates in bank loans and creditline agreements.
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The long-term mean properties of the global climate system and those of turbulent fluid systems are reviewed from a thermodynamic viewpoint. Two general expressions are derived for a rate of entropy production due to thermal and viscous dissipation (turbulent dissipation) in a fluid system. It is shown with these expressions that maximum entropy production in the Earth s climate system suggested by Paltridge, as well as maximum transport properties of heat or momentum in a turbulent system suggested by Malkus and Busse, correspond to a state in which the rate of entropy production due to the turbulent dissipation is at a maximum. Entropy production due to absorption of solar radiation in the climate system is found to be irrelevant to the maximized properties associated with turbulence. The hypothesis of maximum entropy production also seems to be applicable to the planetary atmospheres of Mars and Titan and perhaps to mantle convection. Lorenz s conjecture on maximum generation of available potential energy is shown to be akin to this hypothesis with a few minor approximations. A possible mechanism by which turbulent fluid systems adjust themselves to the states of maximum entropy production is presented as a selffeedback mechanism for the generation of available potential energy. These results tend to support the hypothesis of maximum entropy production that underlies a wide variety of nonlinear fluid systems, including our planet as well as other planets and stars
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The criterion, based on the thermodynamics theory, that the climatic system tends to extremizesome function has suggested several studies. In particular, special attention has been devoted to the possibility that the climate reaches an extremal rate of planetary entropy production.Due to both radiative and material effects contribute to total planetary entropy production,climatic simulations obtained at the extremal rates of total, radiative or material entropy production appear to be of interest in order to elucidate which of the three extremal assumptions behaves more similar to current data. In the present paper, these results have been obtainedby applying a 2-dimensional (2-Dim) horizontal energy balance box-model, with a few independent variables (surface temperature, cloud-cover and material heat fluxes). In addition, climatic simulations for current conditions by assuming a fixed cloud-cover have been obtained. Finally,sensitivity analyses for both variable and fixed cloud models have been carried out
Resumo:
Summary : With regard to exercise metabolism, lactate was long considered as a dead-end waste product responsible for muscle fatigue and a limiting factor for motor performance. However, a large body of evidence clearly indicates that lactate is an energy efficient metabolite able to link the glycolytic pathway with aerobic metabolism and has endocrine-like actions, rather than to be a dead-end waste product. Lactate metabolism is also known to be quickly upregulated by regular endurance training and is thought to be related to exercise performance. However, to what extent its modulation can increase exercise performance in already endurance-trained subjects is unknown. The general hypothesis of this work was therefore that increasing either lactate metabolic clearance rate or lactate availability could, in turn, increase endurance performance. The first study (Study I) aimed at increasing the lactate clearance rate by means of assumed interaction effects of endurance training and hypoxia on lactate metabolism and endurance performance. Although this study did not demonstrate any interaction of training and hypoxia on both lactate metabolism and endurance performance, a significant deleterious effect of endurance training in hypoxia was shown on glucose homeostasis. The methods used to determine lactate kinetics during exercise exhibited some limitations, and the second study did delineate some of the issues raised (Study 2). The third study (Study 3) investigated the metabolic and performance effects of increasing plasma lactate production and availability during prolonged exercise in the fed state. A nutritional intervention was used for this purpose: part of glucose feedings ingested during the control condition was substituted by fructose. The results of this study showed a significant increase of lactate turnover rate, quantified the metabolic fate of fructose; and demonstrated a significant decrease of lipid oxidation and glycogen breakdown. In contrast, endurance performance appeared to be unmodified by this dietary intervention, being at odds with recent reports. Altogether the results of this thesis suggest that in endurance athletes the relationship between endurance performance and lactate turnover rate remains unclear. Nonetheless, the result of the present study raises questions and opens perspectives on the rationale of using hypoxia as a therapeutic aid for the treatment of insulin resistance. Moreover, the results of the second study open perspectives on the role of lactate as an intermediate metabolite and its modulatory effects on substrate metabolism during exercise. Additionally it is suggested that the simple nutritional intervention used in the third study can be of interest in the investigation on the aforementioned roles of lactate. Rsum : Lorsque le lactate est voqu en rapport avec l'exercice, il est souvent considr comme un dchet mtabolique responsable de l'acidose mtabolique, de la fatigue musculaire ou encore comme un facteur limitant de la performance. Or la littrature montre clairement que le lactate se rvle tre plutt un mtabolite utilis efficacement par de nombreux tissus par les voies oxydatives et, ainsi, il peut tre considr comme un lien entre le mtabolisme glycolytique et le mtabolisme oxydatif. De plus on lui prte des proprits endocrines. Il est connu que l'entranement d'endurance accrot rapidement le mtabolisme du lactate, et il est suggr que la performance d'endurance est lie son mtabolisme. Toutefois la relation entre le taux de renouvellement du lactate et la performance d'endurance est peu claire, et, de mme, de quelle manire la modulation de son mtabolisme peut influencer cette dernire. Le but de cette thse tait en consquence d'investiguer de quelle manire et quel degr l'augmentation du mtabolisme du lactate, par l'augmentation de sa clearance et de son turnover, pouvait son tour amliorer la performance d'endurance de sujets entrans. L'objectif de la premire tude a t d'augmenter la clearance du lactate par le biais d'un entranement en conditions hypoxiques chez des cyclistes d'endurance. Bas sur la littrature scientifique existante, on a fait l'hypothse que l'entranement d'endurance et l'hypoxie exerceraient un effet synergtique sur le mtabolisme du lactate et sur la performance, ce qui permettrait de montrer des relations entre performance et mtabolisme du lactate. Les rsultats de cette tude n'ont montr aucun effet synergique sur la performance ou le mtabolisme du lactate. Toutefois, un effet dltre sur le mtabolisme du glucose a t dmontr. Quelques limitations de la mthode employe pour la mesure du mtabolisme du lactate ont t souleves, et partiellement rsolues dans la seconde tude de ce travail, qui avait pour but d'valuer la sensibilit du modle pharmacodynamique utilis pour le calcul du turnover du lactate. La troisime tude a investigu l'effet d'une augmentation de la lactatmie sur le mtabolisme des substrats et sur la performance par une intervention nutritionnelle substituant une partie de glucose ingr pendant l'exercice par du fructose. Les rsultats montrent que les composants dynamiques du mtabolisme du lactate sont significativement augments en prsence de fructose, et que les oxydations de graisse et de glycogne sont significativement diminues. Toutefois aucun effet sur la performance n'a t dmontr. Les rsultats de ces tudes montrent que la relation entre le mtabolisme du lactate et la performance reste peu claire. Les rsultats dltres de la premire tude laissent envisager des pistes de travail, tant donn que l'entranement en hypoxie est considr comme outil thrapeutique dans le traitement de pathologies lies la rsistance l'insuline. De plus les rsultats de la troisime tude ouvrent des perspectives de travail quant au rle du lactate comme intermdiaire mtabolique durant l'exercice ainsi que sur ses effets directs sur le mtabolisme. Ils suggrent de plus que la manipulation nutritionnelle simple qui a t utilise se rvle tre un outil prometteur dans l'tude des rles et effets mtaboliques que peut revtir le lactate durant l'exercice.
