401 research outputs found

    On the Asset Market View of Exchange Rates

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    We offer a critique of the popular notion that the log-change of the real exchange rate equals the log-difference between the IMRSs of economically distinct agents in two economies. Contrary to existing claims, we show that this interpretation does not hold true in reduced-form SDF models that only rely on the absence of arbitrage in asset markets. In structural models, we show that this economic interpretation requires much stronger assumptions that emphasize the importance of goods markets rather than asset markets. We demonstrate the significance of our results for a broad range of topics in the international asset pricing literature

    Surface-atmosphere energy exchanges and their effects on surface climate and boundary layer dynamics in the forest-tundra ecotone in northwestern Canada

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    La région boréale arctique (RBA) couvre une vaste étendue qui lui confère un rôle important dans le système climatique mondial, par ses échanges d'énergie et de matière avec l'atmosphère. La température de l'air dans la région boréale arctique a augmenté à des taux disproportionnés par rapport à la moyenne mondiale, entraînant des changements dans la composition et la structure de la végétation. La RBA comprend l'écotone de la forêt boréale et de la toundra (EFT), qui s'étend sur plus de 10,000 km à travers l'hémisphère nord. La structure et la composition de la végétation varient considérablement à travers l’EFT. Du sud au nord, les arbres deviennent plus courts, plus dispersés et finalement absents. Ce gradient entraîne des variations dans la balance énergétique de surface. Ainsi, des changements dans la composition et la structure de la végétation dans l’EFT pourraient influencer le climat régional futur de ces régions. Ces changements régionaux pourraient se répercuter sur le climat mondial en interagissant avec le cycle du carbone par des changements dans les régimes de perturbations et la profondeur de la couche limite atmosphérique. L'objectif de cette étude était de développer un état des lieux de la variation latitudinale des interactions entre la surface et l’atmosphère et du climat régional à travers l’EFT dans le nord-ouest du Canada. Nous avons utilisé des mesures de covariance des turbulences provenant d’une forêt subarctique en marge de l’EFT et d’une toundra minérale caractérisant l’EFT du nord-ouest du Canada afin de quantifier les différences journalière et saisonnières des échanges d'énergie. Quatre paramètres de surface (albédo, conductance aérodynamique, conductance de surface et facteur de découplage) ont été examinés dans le but d’expliquer les différences dans la balance énergétique de surface. Des observations par radiosonde basées sur des campagnes de terrain et une expérience de modélisation de la couche limite atmosphérique ont été réalisées afin de discuter des conséquences potentielles des changements de végétation sur la dynamique de la couche limite atmosphérique (hauteur, température, humidité) et ses implications pour le climat régional. La forêt subarctique a démontré une meilleure capacité à transférer la chaleur vers l’atmosphère et une plus grande résistance à l'évapotranspiration, se traduisant par des conditions atmosphériques plus chaudes et sèches, spécialement au printemps. En été et automne, une conductance de surface plus élevée sur le site de la toundra s’est traduite par à une plus grande proportion de l'énergie utilisée pour humidifier l'atmosphère, résultant en une couche atmosphérique moins épaisse et un refroidissement régional du climat. La caractérisation des interactions entre la surface et l’atmosphère à travers l’EFT contribuera à améliorer les prédictions des effets des changements de végétation en cours sur le climat régional dans la région boréale arctique.Considering its vast extent, the Arctic-boreal region (ABR) plays an important role in the global climate system through its exchange of energy and matter with the atmosphere. Air temperature across the ABR has been increasing at a higher rate compared to the global average and has led to changes in vegetation composition and structure across the ABR. The ABR includes the forest-tundra ecotone (FTE), spanning more than 10,000 km across the northern hemisphere. As the world’s longest transition zone, the FTE separates the boreal and Arctic biomes over a width of only a few tens to hundreds of kilometers. Vegetation composition and structure varies considerably across the FTE as trees become, from south to north, shorter and more stunted, sparser, and eventually, absent. The associated latitudinal gradient in surface properties results in corresponding latitudinal variations in the energy balance. Thus, changes in the latitudinal variation in surface properties and energy exchanges within the atmospheric boundary layer (ABL) may affect future regional climate across the FTE. The goal of this study was to develop a baseline understanding of the latitudinal variation in surface-atmosphere interactions and atmospheric boundary layer dynamics across the FTE in northwestern Canada. We used paired eddy covariance measurements of surface energy fluxes and supporting environmental measurements at a subarctic woodland (‘woodland’) and a mineral upland tundra site (‘tundra’) to quantify differences in daily and seasonal differences in woodland and tundra properties and energy exchanges. Four bulk surface parameters (albedo, aerodynamic conductance, surface conductance, and decoupling factor) were examined to explain drivers of those differences. Campaign-based radiosonde observations and numerical experiments using an ABL model were used to examine the impacts of a sparse tree cover on ABL dynamics (height, temperature, humidity) and their implications for surface climate compared to treeless tundra. The sparse tree cover at the woodland site showed an enhanced ability to transfer heat into the atmosphere and a higher resistance to evapotranspiration compared to tundra, leading to warmer and drier conditions especially in late winter and spring. In summer and fall, higher bulk surface conductance at the tundra site led to more energy being used to moisten the atmosphere, resulting in a shallower ABL and regional cooling of the atmosphere. Refined characterization of land surface-atmosphere interactions across the FTE will help to project the effect of ongoing vegetation changes on regional climate in the circumpolar Arctic-boreal region

    Obesity and longevity

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    Do Options Contain Information About Excess Bond Returns?

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    There is strong empirical evidence that risk premia in long-term interest rates are time-varying. These risk premia critically depend on interest rate volatility, yet existing research has not examined the impact of time-varying volatility on excess returns for long-term bonds. To address this issue, we incorporate interest rate option prices, which are very sensitive to interest rate volatility, into a dynamic model for the term structure of interest rates. We estimate three-factor affine term structure models using both swap rates and interest rate cap prices. When we incorporate option prices, the model better captures interest rate volatility and is better able to predict excess returns for long-term swaps over short-term swaps, both in- and out-of-sample. Our results indicate that interest rate options contain valuable information about risk premia and interest rate dynamics that cannot be extracted from interest rates alone.

    Circle as methodology: Enacting an Aboriginal paradigm

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    Circle as Methodology is a poetic narrative, a Trickster tale, which is descriptive of an Aboriginal method in use, while being critical of hegemonic beliefs which con ne us. Fyre Jean seeks to engage qualitative researchers from all disciplines in an ongoing dialogue to recognize and resist the oppressive eurocentric attitudes and practices currently shaping research norms. Creatively combining Aboriginal teachings with qualitative design, the author shares insights she gleaned when researching the material for Circle works: Transforming eurocentric consciousness

    A Study of a Physical Education Program on the Manual Dexterity of Educable Mentally Retarded Boys at the Opportunity Training Center at Grand Forks, North Dakota

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    The purpose urns to determine the offsets of physical education on ths manual and finger dexterity of sentally retarded boys. The physical education program consisted aainly of t ti- vities that inproved finger, hand, and an movements. The fourteen boys selected for this study were divid a into two groups of seven each. The control group participated in the pro gran at the Opportunity Training Center but did not take part in the physical education program. The experimental group took pert in the training program at the Center and ware enrolled in a physical education program three hours per week. Both groups participated in their respective programs for a period of eight weeks. At the beginning of the experimental period each group was testsd for fingsr dexterity and manual dexterity by the General Aptitude Test Bettery QATB. The test was again administered to both groups at the end of the experimental period. The null hypothesis was assumed with respect to differences of scores for individual students from pre-test to post-test. The conclusion bassd on this study *** that participation in programs of physical education may improve manual dexterity and finger dexterity among educable mentally retarded boy a. The experimental group shoved a significant iaprovement at the .05 level of confidence on test nine of the GATB test and on test twelve of the GATB test

    Trickster Teaches: Doing Means Being Done To

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    Fourth Amendment--An Acceptable Erosion of the Exclusionary Rule

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