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Distributional Shifts (distributional + shift)
Selected AbstractsTHE DEMAND FOR A RISKY ASSET: SIGNING, JOINTLY AND SEPARATELY, THE EFFECTS OF THREE DISTRIBUTIONAL SHIFTSMETROECONOMICA, Issue 2 2005Thomas Paulsson ABSTRACT We show that, if an individual's utility function exhibits a degree of relative temperance smaller than one, the individual will react, in a plausible way, to each of three common shifts in the stochastic distribution of his wealth, namely to FSD shifts, mean-preserving spreads and increases in downside risk. First, we derive, in a unified setting, necessary and sufficient conditions for signing the comparative-static effects of each of these shifts separately, and, second, we invoke implications of the property of mixed risk aversion to merge these separate conditions into a single sufficient condition for jointly signing all comparative-static effects. [source] The Production Responses of the Competitive Firm to Three Conventional Distributional Shifts: a Unified PerspectiveMETROECONOMICA, Issue 2 2000Wayne Simpson This paper presents a unified perspective on the production responses of the competitive firm to three conventional distributional shifts: (i) a rightward shift of the distribution, (ii) a Rothschild,Stiglitz increase in risk, and (iii) a Menezes et al. increase in downside risk. In particular, assuming that the von Neumann,Morgenstern utility is increasing and concave, and assuming its higher-order derivatives are uniformly signed, we demonstrate that the production responses are unambiguous in the case of price less than or equal to marginal cost. In the alternative case of price greater than marginal cost, we then demonstrate that the production responses can be signed unambiguously by reference to sufficient conditions motivated by absolute risk aversion and by absolute prudence. [source] Historical changes in the phenology of British Odonata are related to climateGLOBAL CHANGE BIOLOGY, Issue 5 2007CHRISTOPHER HASSALL Abstract Responses of biota to climate change take a number of forms including distributional shifts, behavioural changes and life history changes. This study examined an extensive set of biological records to investigate changes in the timing of life history transitions (specifically emergence) in British Odonata between 1960 and 2004. The results show that there has been a significant, consistent advance in phenology in the taxon as a whole over the period of warming that is mediated by life history traits. British odonates significantly advanced the leading edge (first quartile date) of the flight period by a mean of 1.51 ±0.060 (SEM, n=17) days per decade or 3.08±1.16 (SEM, n=17) days per degree rise in temperature when phylogeny is controlled for. This study represents the first review of changes in odonate phenology in relation to climate change. The results suggest that the damped temperature oscillations experienced by aquatic organisms compared with terrestrial organisms are sufficient to evoke phenological responses similar to those of purely terrestrial taxa. [source] Climate change and the outbreak ranges of two North American bark beetlesAGRICULTURAL AND FOREST ENTOMOLOGY, Issue 2 2002David W. Williams Abstract 1,One expected effect of global climate change on insect populations is a shift in geographical distributions toward higher latitudes and higher elevations. Southern pine beetle Dendroctonus frontalis and mountain pine beetle Dendroctonus ponderosae undergo regional outbreaks that result in large-scale disturbances to pine forests in the south-eastern and western United States, respectively. 2,Our objective was to investigate potential range shifts under climate change of outbreak areas for both bark beetle species and the areas of occurrence of the forest types susceptible to them. 3,To project range changes, we used discriminant function models that incorporated climatic variables. Models to project bark beetle ranges employed changed forest distributions as well as changes in climatic variables. 4,Projected outbreak areas for southern pine beetle increased with higher temperatures and generally shifted northward, as did the distributions of the southern pine forests. 5,Projected outbreak areas for mountain pine beetle decreased with increasing temperature and shifted toward higher elevation. That trend was mirrored in the projected distributions of pine forests in the region of the western U.S. encompassed by the study. 6,Projected outbreak areas for the two bark beetle species and the area of occurrence of western pine forests increased with more precipitation and decreased with less precipitation, whereas the area of occurrence of southern pine forests decreased slightly with increasing precipitation. 7,Predicted shifts of outbreak ranges for both bark beetle species followed general expectations for the effects of global climate change and reflected the underlying long-term distributional shifts of their host forests. [source] The Production Responses of the Competitive Firm to Three Conventional Distributional Shifts: a Unified PerspectiveMETROECONOMICA, Issue 2 2000Wayne Simpson This paper presents a unified perspective on the production responses of the competitive firm to three conventional distributional shifts: (i) a rightward shift of the distribution, (ii) a Rothschild,Stiglitz increase in risk, and (iii) a Menezes et al. increase in downside risk. In particular, assuming that the von Neumann,Morgenstern utility is increasing and concave, and assuming its higher-order derivatives are uniformly signed, we demonstrate that the production responses are unambiguous in the case of price less than or equal to marginal cost. In the alternative case of price greater than marginal cost, we then demonstrate that the production responses can be signed unambiguously by reference to sufficient conditions motivated by absolute risk aversion and by absolute prudence. [source] Evidence for bias in estimates of local genetic structure due to sampling schemeANIMAL CONSERVATION, Issue 3 2006E. K. Latch Abstract Traditional population genetic analyses typically seek to characterize the genetic substructure caused by the nonrandom distribution of individuals. However, the genetic structuring of adult populations often does not remain constant over time, and may vary relative to season or life-history stages. Estimates of genetic structure may be biased if samples are collected at a single point in time, and will reflect the social organization of the species at the time the samples were collected. The complex population structures exhibited by many migratory species, where temporal shifts in social organization correspond to a large-scale shift in geographic distribution, serve as examples of the importance that time of sampling can have on estimates of genetic structure. However, it is often fine-scale genetic structure that is crucial for defining practical units for conservation and management and it is at this scale that distributional shifts of organisms relative to the timing of sampling may have a profound yet unrecognized impact on our ability to interpret genetic data. In this study, we used the wild turkey to investigate the effects of sampling regime on estimates of genetic structure at local scales. Using mitochondrial sequence data, nuclear microsatellite data and allozyme data, we found significant genetic structuring among localized winter flocks of wild turkeys. Conversely, we found no evidence for genetic structure among sampling locations during the spring, when wild turkeys exist in mixed assemblages of genetically differentiated winter flocks. If the lack of detectable genetic structure among individuals is due to an admixture of social units as in the case of wild turkeys during the spring, then the FIS value rather than the FST value may be the more informative statistic in regard to the levels of genetic structure among population subunits. [source] | ||||||||||