996 research outputs found

    Sensitivity of Species Habitat-Relationship Model Performance to Factors of Scale

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    Researchers have come to different conclusions about the usefulness of habitat-relationship models for predicting species presence or absence. This difference frequently stems from a failure to recognize the effects of spatial scales at which the models are applied. We examined the effects of model complexity, spatial data resolution, and scale of application on the performance of bird habitat relationship (BHR) models on the Craig Mountain Wildlife Management Area and on the Idaho portion of the U.S. Forest Service\u27s Northern Region. We constructed and tested BHR models for 60 bird species detected on the study areas. The models varied by three levels of complexity (amount of habitat information) and three spatial data resolutions (0.09 ha, 4 ha, 10 ha). We tested these models at two levels of analysis: the site level (a homogeneous area \u3c0.5 ha) and cover-type level (an aggregation of many similar sites of a similar land-cover type), using correspondence between model predictions and species detections to calculate kappa coefficients of agreement. Model performance initially increased as models became more complex until a point was reached where omission errors increased at a rate greater than the rate at which commission errors were decreasing. Heterogeneity of the study areas appeared to influence the effect of model complexity. Changes in model complexity resulted in a greater decrease in commission error than increase in omission error. The effect of spatial data resolution on the performance of BHR models was influenced by the variability of the study area. BHR models performed better at cover-type levels of analysis than at the site level for both study areas. Correct-presence estimates (1 − minus percentage omission error) decreased slightly as number of species detections increased on each study area. Correct-absence estimates (1 − percentage commission error) increased as number of species detections increased on each study area. This suggests that a large number of detections may be necessary to achieve reliable estimates of model accuracy

    Neuropeptide Y concentrations in cerebrospinal fluid are unchanged in obesity

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    Neuropeptide Y (NPy) is a potent centrally acting appetite-stimulating peptide implicated in the regulation of energy balance. It induces hyperphagia and obesity when injected into the rat hypothalamus. Hypothalamic NPY and NPY mRNA levels are increased in spontaneously obese rats, suggesting that it may be involved in causing obesity in rodents. It is not known whether NPY has a role in the pathogenesis of obesity in man. NPY is found in human cerebrospinal fluid (CSF) and we have therefore compared CSF NPY levels in normal obese and non-obese individuals to determine whether NPY concentrations might be increased in obesity. We studied 25 clinically normal subjects (age 67 ± 5 years. male 11. female 14) undergoing spinal anaesthesia. None had any significant illness. Samples of 1 ml were freeze-dried and reconstituted to 100 ul and 35ul aliquots were assayed for NPY using an in-house RIA. CSF NPY levels were not correlated with body mass index (BMI) (r=O.088. p=O.673) and there were no differences in NPY concentrations between groups of subjects stratified for BMI: BMI 25 (n=ll), 702 ± 55 fmol/ml (differences between all groups. p>0l). CSF NPY levels are therefore not increased in human obesity. NPY is found in many brain regions outside the hypothalamic appetite-regulating nuclei, which could contribute to CSF levels. This negative observation does not therefore exclude a role of the peptide, acting specifically in the hypothalamus, in contributing to human obesity

    Symmetry breaking in crossed magnetic and electric fields

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    We present the first observations of cylindrical symmetry breaking in highly excited diamagnetic hydrogen with a small crossed electric field, and we give a semiclassical interpretation of this effect. As the small perpendicular electric field is added, the recurrence strengths of closed orbits decrease smoothly to a minimum, and revive again. This phenomenon, caused by interference among the electron waves that return to the nucleus, can be computed from the azimuthal dependence of the classical closed orbits.Comment: 4 page REVTeX file including 5 postscript files (using psfig) Accepted for publication in Physical Review Letters. Difference from earlier preprint: we have discovered the cause of the earlier apparent discrepancy between experiment and theory and now achieve excellent agreemen

    London governance and the politics of neighbourhood planning: a case for investigation

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    The Localism Act 2011 has successfully devolved planning powers to over 2,500 English communities, involving 14 million people, with over 700 ‘made’ neighbourhood plans legitimised by referendum. In London, however, there are less than one-tenth of the made plans than in the rest of England. Institutional resistance and policy choices may be implicated. Two national studies of neighbourhood planning are reviewed. The role of the local authority is found to be a crucial factor in determining progress, and issues of social deprivation and unequal access are highlighted. Theorisation is considered by reference to a range of academic studies of localism and neighbourhood planning. Distinctions made between ‘representative’ and ‘community’ localism, and objections to anti-political effects, are noted. There has been remarkably little research into borough governance and neighbourhood planning in the capital. Based upon evidence of anomalous and differentiated governance practice, a study in London is called for

    ‘If independence goes, the planning system goes’: New Political Governance and the English Planning Inspectorate

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    Radical restructuring of 'arms-length' government bodies following the 2010 UK national election signalled a change in relations between government and the civil service. This was seen as a major shift in modes of governance from 'new public management' to a more politicised mode of 'new political governance'. This paper presents an analysis of the impacts of these shifts on the English Planning Inspectorate, an executive agency central to the land-use planning system. It identifies measures by ministers to increase control over the Inspectorate that represent a shift in governance culture and a shift in the planning system itself

    The Emerging Aversion to Inequality: Evidence from Poland 1992-2005

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    This paper provides an illustration of the changing tolerance for inequality in a context of radical political and economic transformation and rapid economic growth. We focus on the Polish experience of transition and explore self-declared attitudes of the citizens. Using monthly representative surveys of the population, realized by the Polish poll institute (CBOS) from 1992 to 2005, we identify a structural break in the relation between income inequality and subjective evaluation of well-being. The downturn in the tolerance for inequality (1997) coincides with the increasing distrust of political elites.http://deepblue.lib.umich.edu/bitstream/2027.42/64387/1/wp919.pd

    Cerebrospinal fluid velocity amplitudes within the cerebral aqueduct in healthy children and patients with Chiari I malformation

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/133626/1/jmri25160_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/133626/2/jmri25160.pd

    The relative contribution of climate to changes in lesser prairie-chicken abundance

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    Citation: Ross, B. E., Haukos, D., Hagen, C., & Pitman, J. (2016). The relative contribution of climate to changes in lesser prairie-chicken abundance. Ecosphere, 7(6), 11. doi:10.1002/ecs2.1323Managing for species using current weather patterns fails to incorporate the uncertainty associated with future climatic conditions; without incorporating potential changes in climate into conservation strategies, management and conservation efforts may fall short or waste valuable resources. Understanding the effects of climate change on species in the Great Plains of North America is especially important, as this region is projected to experience an increased magnitude of climate change. Of particular ecological and conservation interest is the lesser prairie-chicken (Tympanuchus pallidicinctus), which was listed as "threatened" under the U.S. Endangered Species Act in May 2014. We used Bayesian hierarchical models to quantify the effects of extreme climatic events (extreme values of the Palmer Drought Severity Index [PDSI]) relative to intermediate (changes in El Nino Southern Oscillation) and long-term climate variability (changes in the Pacific Decadal Oscillation) on trends in lesser prairie-chicken abundance from 1981 to 2014. Our results indicate that lesser prairie-chicken abundance on leks responded to environmental conditions of the year previous by positively responding to wet springs (high PDSI) and negatively to years with hot, dry summers (low PDSI), but had little response to variation in the El Nino Southern Oscillation and the Pacific Decadal Oscillation. Additionally, greater variation in abundance on leks was explained by variation in site relative to broad-scale climatic indices. Consequently, lesser prairie-chicken abundance on leks in Kansas is more strongly influenced by extreme drought events during summer than other climatic conditions, which may have negative consequences for the population as drought conditions intensify throughout the Great Plains

    Transitions/relaxations in polyester adhesive/PET system

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    The correlations between the transitions and the dielectric relaxation processes of the oriented poly(ethylene terephthalate) (PET) pre-impregnated of the polyester thermoplastic adhesive have been investigated by differential scanning calorimetry (DSC) and dynamic dielectric spectroscopy (DDS). The thermoplastic polyester adhesive and the oriented PET films have been studied as reference samples. This study evidences that the adhesive chain segments is responsible for the physical structure evolution in the PET-oriented film. The transitions and dielectric relaxation modes’ evolutions in the glass transition region appear characteristic of the interphase between adhesive and PET film, which is discussed in terms of molecular mobility. The storage at room temperature of the adhesive tape involves the heterogeneity of the physical structure, characterized by glass transition dissociation. Thus, the correlation between the transitions and the dielectric relaxation processes evidences a segregation of the amorphous phases. Therefore, the physical structure and the properties of the material have been linked to the chemical characteristics

    Surgical reversal of prolonged blindness from a metastatic neuroblastoma

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    Reports of tumor-related anterior visual pathway blindness that have resolved after surgical decompression are rare. The longest reported duration of tumor-related blindness completely reversed by optic nerve decompression is 3 days. We describe a pediatric patient with 7 days of no light perception who experienced reversal of blindness following tumor resection and optic nerve decompression.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47141/1/381_2004_Article_1062.pd
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