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Expected Pattern (expected + pattern)
Selected AbstractsLong-Term Debt and Optimal Policy in the Fiscal Theory of the Price LevelECONOMETRICA, Issue 1 2001John H. Cochrane The fiscal theory says that the price level is determined by the ratio of nominal debt to the present value of real primary surpluses. I analyze long-term debt and optimal policy in the fiscal theory. I find that the maturity structure of the debt matters. For example, it determines whether news of future deficits implies current inflation or future inflation. When long-term debt is present, the government can trade current inflation for future inflation by debt operations; this tradeoff is not present if the government rolls over short-term debt. The maturity structure of outstanding debt acts as a "budget constraint" determining which periods' price levels the government can affect by debt variation alone. In addition, debt policy,the expected pattern of future state-contingent debt sales, repurchases and redemptions,matters crucially for the effects of a debt operation. I solve for optimal debt policies to minimize the variance of inflation. I find cases in which long-term debt helps to stabilize inflation. I also find that the optimal policy produces time series that are similar to U.S. surplus and debt time series. To understand the data, I must assume that debt policy offsets the inflationary impact of cyclical surplus shocks, rather than causing price level disturbances by policy-induced shocks. Shifting the objective from price level variance to inflation variance, the optimal policy produces much less volatile inflation at the cost of a unit root in the price level; this is consistent with the stabilization of U.S. inflation after the gold standard was abandoned. [source] Partitioning phylogenetic and adaptive components of the geographical body-size pattern of New World birdsGLOBAL ECOLOGY, Issue 1 2008Lizabeth Ramirez ABSTRACT Aim To evaluate seasonal body-size patterns for New World birds in geographical space, to develop environmental models to explain the gradients, and to estimate phylogenetic and adaptive contributions. Location The Western Hemisphere. Methods We used range maps to generate gridded geometric mean body masses. Summer and winter patterns were distinguished based on breeding and non-breeding ranges. We first generated the geographical gradients, followed by phylogenetic eigenvector regression to generate body sizes predicted by the birds' positions in a phylogenetic tree, which were used to generate the expected phylogenetic gradient. Subtracting the expected pattern from the observed pattern isolated the adaptive component. Ordinary least squares multiple-regression models examined factors influencing the phylogenetic, adaptive and combined components of the seasonal body-size patterns, and non-spatial and spatial models were compared. Results Birds are larger in the temperate zones than in the tropics. The gradient is quantitatively stronger in winter than in summer. Regression models explained 66.6% of the variance in summer mass and 45.9% of the variance in winter mass. In summer, phylogenetic and adaptive responses of birds contribute equally to the gradient. In winter, the gradient in North America is much stronger than that expected by taxonomic turnover, and responses of species independent of their family membership drive the overall pattern. Main conclusions We confirm Bergmann's rule in New World birds and conclude that winter temperatures ultimately drive the pattern, exerting selection pressures on birds that overwhelm patterns expected by phylogenetic inertia at the family level. However, in summer, the movement of migratory species into the temperate zone weakens the gradient and generates a pattern more congruent with that expected from the taxonomic composition of the fauna. The analytical method we develop here represents a useful tool for partitioning the phylogenetic and non-phylogenetic components of spatially explicit macroecological data. [source] The Associations Between Basal Salivary Cortisol and Illness Symptomatology in Chronic Fatigue SyndromeJOURNAL OF APPLIED BIOBEHAVIORAL RESEARCH, Issue 3 2008Susan Torres-Harding Hypocortisolism has been reported in chronic fatigue syndrome (CFS), with the significance of this finding to disease etiology unclear. This study examined cortisol levels and their relationships with symptoms in a group of 108 individuals with CFS. CFS symptoms examined included fatigue, pain, sleep difficulties, neurocognitive functioning, and psychiatric status. Alterations in cortisol levels were examined by calculation of mean daily cortisol, and temporal variation in cortisol function was examined by means of a regression slope. Additionally, deviation from expected cortisol diurnal pattern was determined via clinical judgment. Results indicated that fatigue and pain were associated with salivary cortisol levels. In particular, variance from the expected pattern of cortisol was associated with increased levels of fatigue. The implications of these findings are discussed. [source] Hatching asynchrony and maternal androgens in egg yolks of House WrensJOURNAL OF AVIAN BIOLOGY, Issue 1 2001Lisa A. Ellis Synchronously and asynchronously hatching clutches of House Wrens Troglodytesaedon usually do not differ in reproductive success. Thus late-hatching nestlings in asynchronously hatching clutches somehow overcome any age- and size-related disadvantages of hatching after their nest-mates. One possible way for them to do this is for female House Wrens to add maternal androgens to the yolk of late-hatching eggs. We tested this hypothesis in a wild population of House Wrens that produces both asynchronously and synchronously hatching clutches. Yolks of eggs from both types of clutches were biopsied and the eggs returned to their nests to hatch. Radioimmunoassays revealed that total androgen levels in the yolk varied within and among clutches. However, total androgen levels in yolks did not vary predictably with egg position in either synchronously or asynchronously hatching clutches. Thus, deposition of androgens in yolk did not follow the expected pattern based on the potential for sibling competition in House Wrens. [source] Distributions of tree species along point bars of 10 rivers in the south-eastern US Coastal PlainJOURNAL OF BIOGEOGRAPHY, Issue 1 2006Kevin M. Robertson Abstract Aim, To determine the degree to which rivers within the south-eastern US Coastal Plain show a predictable spatial distribution of floodplain tree species along each point bar of river bends in relation to elevation and/or soil texture, as seen on the Bogue Chitto River, Louisiana, USA. Also, to understand spatial patterns of tree species on land created during river-bend migration, and to interpret which physical characteristics of rivers predict this pattern of vegetation. Location, The south-eastern US Coastal Plain. Methods, Ten randomly selected rivers within a portion of the region were studied. At each of 10 river bends per river, a census of trees and shrubs was taken and elevation and soil texture were measured at upstream, mid- and downstream locations along the forest,point bar margin. To identify physical characteristics of rivers that are predictive of patterns of tree species along point bars, aerial photographs, hydrographs and field data were analysed. Results, Tree species composition varied predictably among the three point bar locations, corresponding to an elevation gradient on each bar, on seven of 10 rivers. Species occupying a given point bar location on one river usually occupied the same location on other rivers, in accordance with species-elevation associations identified in past studies of floodplain forests. Multivariate analysis of river characteristics suggested that rivers failing to show the expected pattern were those with relatively low stream energy and geomorphic dynamics and/or those with hydrological regimes altered by upstream dams. Main conclusions, A distinct pattern of streamside forest community structure is related to fluvial geomorphic processes characterizing many rivers within the south-eastern US Coastal Plain. Characteristics of rivers required to promote the predicted pattern of tree species include a single, meandering channel with point bars; an intermediate level of stream energy; a natural hydrological regime; and location in a biome where a large number of tree species are capable of colonizing point bars. [source] Polymorphism and signature of selection in the MHC class I genes of the three-spined stickleback Gasterosteus aculeatusJOURNAL OF FISH BIOLOGY, Issue 2006H. Schaschl The role and intensity of positive selection maintaining the polymorphism of major histocompatibility complex (MHC) class I genes in the three-spined stickleback Gasterosteus aculeatus was investigated. The highly polymorphic set of MHC class I genes found was organized in a single linkage group. Between 5 and 14 sequence variants per individual were identified by single-stranded conformation polymorphism (SSCP) analysis. Segregation analysis studied in 10 three-spined stickleback families followed the expected pattern of Mendelian inheritance. The gamete fusion in three-spined stickleback thus seems to be random with respect to the MHC class I genes. The DNA sequence analyses showed that the expressed MHC class I loci are under strong selection pressure, possibly mediated by parasites. Codons that were revealed to be under positive selection are potentially important in antigen binding. MHC class I sequences did not form significant supported clusters within a phylogenetic tree. Analogous to MHC class II genes, it was not possible to assign the class I sequences to a specific locus, suggesting that the class I genes may have been generated by recent gene duplication. [source] Habitat-dependent foraging in a classic predator,prey system: a fable from snowshoe haresOIKOS, Issue 2 2005Douglas W. Morris Current research contrasting prey habitat use has documented, with virtual unanimity, habitat differences in predation risk. Relatively few studies have considered, either in theory or in practice, simultaneous patterns in prey density. Linear predator,prey models predict that prey habitat preferences should switch toward the safer habitat with increasing prey and predator densities. The density-dependent preference can be revealed by regression of prey density in safe habitat versus that in the riskier one (the isodar). But at this scale, the predation risk can be revealed only with simultaneous estimates of the number of predators, or with their experimental removal. Theories of optimal foraging demonstrate that we can measure predation risk by giving-up densities of resource in foraging patches. The foraging theory cannot yet predict the expected pattern as predator and prey populations covary. Both problems are solved by measuring isodars and giving-up densities in the same predator,prey system. I applied the two approaches to the classic predator,prey dynamics of snowshoe hares in northwestern Ontario, Canada. Hares occupied regenerating cutovers and adjacent mature-forest habitat equally, and in a manner consistent with density-dependent habitat selection. Independent measures of predation risk based on experimental, as well as natural, giving-up densities agreed generally with the equal preference between habitats revealed by the isodar. There was no apparent difference in predation risk between habitats despite obvious differences in physical structure. Complementary studies contrasting a pair of habitats with more extreme differences confirmed that hares do alter their giving-up densities when one habitat is clearly superior to another. The results are thereby consistent with theories of adaptive behaviour. But the results also demonstrate, when evaluating differences in habitat, that it is crucial to let the organisms we study define their own habitat preference. [source] The demographic transition revisited as a global processPOPULATION, SPACE AND PLACE (PREVIOUSLY:-INT JOURNAL OF POPULATION GEOGRAPHY), Issue 1 2004David S. Reher Abstract With dramatic declines in fertility taking place throughout the world, it is increasingly important to understand the demographic transition as a global process. While this universality was a cornerstone of classic transition theories, for many decades it was largely neglected by experts because fertility in the developing world did not seem to follow the expected pattern. When comparing earlier and more recent transition experiences, important similarities and disparities can be seen. Everywhere mortality decline appears to have played a central role for fertility decline. The differences in the timing of the response of fertility to mortality decline, with very small gaps historically and prolonged ones in more recent transitions, plus the much more rapid decline in vital rates in many developing countries, constitute an important challenge to any general explanation of the process. The specific characteristics of recent transitions have led to decades of higher population growth rates, and promise to give way to much more rapid dynamics of population ageing in many countries. This may limit the ability of newcomers to take full advantage of the demographic transition for the social and economic modernisation of their societies. Copyright © 2004 John Wiley & Sons, Ltd. [source] Phenotypic Expression of Recurrent Disease After Liver TransplantationAMERICAN JOURNAL OF TRANSPLANTATION, Issue 5 2010J. G. O'Grady Recurrence of the primary disease has become a major focus for transplant hepatologists both when investigating graft dysfunction and when tailoring immunosuppression to maximize graft survival. However, disease recurrence varies in penetrance, can be predictable or random, and does not always conform to the expected pattern of disease. The cholestatic hepatitis syndromes associated with hepatitis B and C are the most dramatic examples of phenotypic change. Being on immunosuppressive drugs may intensify the progression of infectious and malignant diseases, but this effect is not predictable. A significant minority of patients with each of the autoimmune diseases, counter-intuitively, get recurrent disease despite immunosuppression of a potency that is adequate to prevent rejection of the liver graft. Disease patterns emerge after liver transplantation for cryptogenic cirrhosis that shed light on the cause of the native liver disease, for example, nonalcohol-related fatty liver disease and autoimmune hepatitis. The phenotypic expression of disease recurrence can be modified by specific drugs used for immunosuppression and by HLA-antigen matching profiles. Understanding and modifying the phenotypic expression of recurrent disease after liver transplantation is a fertile area for research and continued refinement of clinical care. [source] Declining and low fecal corticoids are associated with distress, not acclimation to stress, during the translocation of African rhinocerosANIMAL CONSERVATION, Issue 1 2010W. L. Linklater Abstract Concentrations of adrenal steroid metabolites in feces are routinely used to assess the welfare of animals that are the subject of conservation efforts. The assumption that low and declining corticoid concentrations indicate the absence of stress and acclimation, respectively, is often made without experimental support or wild-animal comparisons, although intrinsic control of adrenal steroids might occur even under ongoing stress and distress. We adopted the capture and 11-week captivity of 18 black (Diceros bicornis: 11 males, seven females) and 52 white (Ceratotherium simum: 22 males, 30 females) rhinoceros as an experimental test of the relationship between corticoid concentrations and stress (translocation) and measured for suppressed gonad function as an indicator of distress , the biological cost of cumulative stressors. Fecal samples collected from the rectum at capture and during captivity were stored frozen and their corticoid, and androgen (in males) or progestin (in females), concentrations determined by radioimmunoassay. Corticoid profiles followed the expected pattern of being two to five times pre-capture levels (ng g,1: black rhino: female 24.5±3.7, male 23.9±2.2; white rhino: female 16.3±1.6, male 12.3±2.4) for up to 17 days after capture and declined with time in captivity. Black rhinoceros and male white rhinoceros corticoids declined below pre-capture values and were associated with suppressed levels of androgens and progestins with increased time in captivity. Declining corticoids could not be interpreted as acclimation or the absence of stressors, without also measuring for distress in African rhinoceros. White rhinoceros female corticoid values remained elevated, although their gonad steroid levels were also suppressed. We discuss our findings for the management of rhinoceros in the wild and captivity. [source] Quantitative comparison of the diversity of landscapes with actual vs. potential natural vegetationAPPLIED VEGETATION SCIENCE, Issue 2 2000Carlo Ricotta Abstract. In the past 20 years, several metrics have been developed to quantify various aspects of landscape structure and diversity in space and time, and most have been tested on grid-based thematic maps. Once landscape patterns have been quantified, their effects on ecological functions can be explained if the expected pattern in the absence of specific processes is known. This type of expected pattern has been termed a neutral landscape model. In the landscape-ecological literature, researchers traditionally adopt random and fractal computer-generated neutral landscape models to verify the expected relationship between a given ecological process and landscape spatial heterogeneity. Conversely, little attention has been devoted to distribution patterns of potential natural vegetation (PNV) as an ecological baseline for the evaluation of pattern-process interactions at the landscape scale. As an application for demonstration, we propose a neutral model based on PNV as a possible reference for a quantitative comparison with actual vegetation (AC V) distribution. Within this context, we introduce an evenness-like index termed ,actual-to-potential entropy ratio' (HA/P = HACV/HPNV, where H is Shannon's entropy). Results show that, despite the hypothetical character of most PNV maps, the use of PNV distribution as a baseline for a quantitative comparison with ACV distribution may represent a first step towards a general model for the evaluation of the effects of disturbance on vegetation patterns and diversity. [source] Pattern of carcinoembryonic antigen drop after laparoscopic radiofrequency ablation of liver metastasis from colorectal carcinomaCANCER, Issue 1 2006Mohammed Ghanamah M.D. Abstract BACKGROUND Laparoscopic radiofrequency ablation (RFA) is being increasingly used for local control of hepatic metastasis from colorectal carcinoma (CRC). After surgical resection of colorectal liver metastasis, carcinoembryonic antigen (CEA) values fall within 2 weeks, making this a useful parameter to follow shortly after surgery. Little is known, however, about the expected pattern of the CEA drop after RFA. METHODS From September 1998 to October 2002, RFA to CRC liver metastasis was performed on 144 patients. A subset of 17 patients were studied who had no evidence of extrahepatic disease preoperatively, had all detectable tumor ablated intraoperatively, and who on long-term follow-up (up to 15 months) had no evidence of recurrent disease. Serum CEA was determined preoperatively, on the first postoperative day, at 1 week, and every 3 months afterwards. A computed tomography (CT) scan of the abdomen and pelvis was obtained every 3 months postoperatively. RESULTS Ten (58.8%) patients showed an increase in CEA on postoperative Day 1, averaging 38.3% compared with the preoperative value. CEA then fell to 50% of the preoperative value, on average, on Day 7 postoperatively and only reached its nadir at 3 months. CONCLUSIONS Unlike resection patients, those undergoing ablation show an initial rise in CEA, probably due to release from the ablated tissue. Although heating of RFA would be expected to destroy CEA, the initial rise and slow drop postoperatively argue for a release of immunoreactive CEA from the ablated zone. This slow decline in CEA indicates that several months should pass before assessing the extent of potential residual disease. Cancer 2006. © 2006 American Cancer Society. [source] Using the Barnes Language Assessment with older ethnic minority groupsINTERNATIONAL JOURNAL OF GERIATRIC PSYCHIATRY, Issue 4 2009Victoria Ramsey Abstract Objective There are many issues concerning the assessment of older people from ethnic minority groups, the most significant being the language barrier experienced by those whose English is an additional language (EAL). This study aimed to test the hypothesis that EAL participants would score less well than those with English as a first language (EFL) on the sub-tests of the Barnes Language Assessment (BLA), elucidate the reasons for any such differences and discuss the implications. Methods The Barnes Language Assessment (BLA) is an accurate tool providing information about expected patterns of language in different dementia syndromes. This study compares the performance of EAL participants with EFL participants. The BLA was administered to 144 participants, divided into sub-groups with respect to age, gender and educational background, none of whom had a working diagnosis of dementia. Results Results suggest that EAL speakers performed less well compared to EFL speakers when other variables were matched. Significantly better BLA scores, at the one percent level, were found in both EAL and EFL groups with higher educational achievement for eight of the 15 sub-tests. Conclusion Differences were found in performance on the BLA between EAL and EFL participants. The degree of difference between EAL and EFL speakers decreased as educational achievement rose. The consequences of these findings for service delivery and the problems of recruitment of older EAL participants are discussed. Copyright © 2009 John Wiley & Sons, Ltd. [source] The molecular diversity of the methanogenic community in a hypereutrophic freshwater lake determined by PCR-RFLPJOURNAL OF APPLIED MICROBIOLOGY, Issue 5 2004C. Whitby Abstract Aims:, To combine database-held sequence information with a programme of experimental molecular ecology to define the methanogenic community of a hypereutrophic lake by a PCR-restriction fragment length polymorphism (RFLP) analysis. Methods and Results:, Methanogen diversity in a hypereutrophic freshwater lake was analysed using 16S rDNA PCR-RFLP. Database-held 16S rRNA gene sequences for 76 diverse methanogens were analysed for specific restriction sites that permitted unequivocal differentiation of methanogens. Restriction digestion and agarose gel electrophoresis of the 16S rDNA from selected methanogen pure cultures generated observed restriction profiles that corroborated the expected patterns. This method was then tested by analysing methanogen diversity in samples obtained over 1 year from sediment and water samples taken from the same sampling site. Conclusions:, Restriction analysis of the 16S rRNA gene sequences from 157 methanogen clones generated from lakewater and sediment samples showed that over 50% were similar to Methanoculleus spp. Furthermore, a total of 16 RFLP types (1,16) were identified, eight of which contained no cultured representative archaeal 16S rRNA gene sequences. Significance and Impact of the Study:, This RFLP strategy provides a robust and reliable means to rapidly identify methanogens in the environment. [source] Analysis of plant species diversity with respect to island characteristics on the Channel Islands, CaliforniaJOURNAL OF BIOGEOGRAPHY, Issue 3 2000Aaron Moody Abstract Aim Species richness of native, endemic, and exotic plant groups is examined relative to island area, disturbance history, geological history, and other physical characteristics. Of particular interest are the biogeographic factors that underlie (a) differences in species-area and species-isolation relationships between plant groups; and (b) adherence or departure of individual islands and/or plant groups from expected patterns. Location The eight Channel Islands lie along the continental margin between the U.S./Mexico border and Point Conception, CA. They range in size from 2.6 to 249 km2, and are located from 20 to 100 km off the coast. The islands are known for their high degree of plant endemism, and they have undergone a long history of human occupation by indigenous peoples, followed by over a century of intensive grazing and other biotic disturbances. Methods The study is based on linear regression and residual analysis. Cases where individual islands and/or specific plant groups do not adhere to patterns expected under species-area and species-isolation paradigms, are evaluated with respect to other island characteristics that are not captured by considering only island size and isolation. Results All three plant groups exhibit strong, positive relationships between species richness and island size. For native species, the variance that remains after consideration of island size is largely explained by island isolation. For exotic species, residuals from the species-area relationship are unrelated to isolation. For endemic species, residuals from the species-area relationship are negatively related to isolation. Several islands are outliers for endemic and exotic species, for which richness values are not explained by either island area or isolation. Main,conclusions Species-area and species-isolation relationships for native, endemic, and exotic plant groups differ in accordance with hypothesized differences in the biogeographic factors that govern species diversity for these three groups. Most notably, endemic richness increases with isolation, suggesting the influence of this variable on processes of speciation and relictualism. These general relationships persist despite a long and varied history of human activity on the islands. Analysis of residuals suggests that deviations from expected patterns correspond to island-specific biogeographic factors. It is hypothesized that primary among these factors are land-use history, island environmental characteristics, and community-type richness. [source] | |||||||||||||||||||