2,628 research outputs found

    A multi-scale distribution model for non-equilibrium populations suggests resource limitation in an endangered rodent.

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    Species distributions are known to be limited by biotic and abiotic factors at multiple temporal and spatial scales. Species distribution models, however, frequently assume a population at equilibrium in both time and space. Studies of habitat selection have repeatedly shown the difficulty of estimating resource selection if the scale or extent of analysis is incorrect. Here, we present a multi-step approach to estimate the realized and potential distribution of the endangered giant kangaroo rat. First, we estimate the potential distribution by modeling suitability at a range-wide scale using static bioclimatic variables. We then examine annual changes in extent at a population-level. We define available habitat based on the total suitable potential distribution at the range-wide scale. Then, within the available habitat, model changes in population extent driven by multiple measures of resource availability. By modeling distributions for a population with robust estimates of population extent through time, and ecologically relevant predictor variables, we improved the predictive ability of SDMs, as well as revealed an unanticipated relationship between population extent and precipitation at multiple scales. At a range-wide scale, the best model indicated the giant kangaroo rat was limited to areas that received little to no precipitation in the summer months. In contrast, the best model for shorter time scales showed a positive relation with resource abundance, driven by precipitation, in the current and previous year. These results suggest that the distribution of the giant kangaroo rat was limited to the wettest parts of the drier areas within the study region. This multi-step approach reinforces the differing relationship species may have with environmental variables at different scales, provides a novel method for defining available habitat in habitat selection studies, and suggests a way to create distribution models at spatial and temporal scales relevant to theoretical and applied ecologists

    Revision of a health and physical education program through a teacher-parent-community committee study

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    Thesis (M.A.)--Boston University, 1946. This item was digitized by the Internet Archive

    The Effect of Motivational General-Mastery Imagery on Reaction Time Performance and Heart Rate

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    Research suggests that imagery can reduce reaction time (Alikhani et al., 2001; Grouios, 1992; Hanshaw & Sukal, 2016; Iftikhar et al., 2018; Shanks & Cameron, 2000). Previous studies examining the imagery and reaction time relationship have almost exclusively focused on motor imagery. Additionally, a recent study by McNeil and colleagues (2019) concluded that imagery training improved decision time variables, but not overall reactive agility. Individuals may not be able to generate unpredictable stimuli during imagery. The purpose of this study was to examine the effects of motivational general-mastery (MG-M) imagery on reaction time and heart rate. Reaction time was measured using the Dynavision D2 visuomotor training device. It was hypothesized that the use of an MG-M imagery intervention will significantly increase reaction time and the number of hits during testing, and participants in the MG-M imagery group would have a lower heart rate range from beginning to end of test. A within-subjects and between-subjects pre-posttreatment design was implemented. Participants were 9 NCAA Division I student-athletes. The effectiveness of the imagery intervention on reaction time, number of hits, and heart rate range was assessed using nonparametric Wilcoxon-Signed rank tests and Mann-Whitney U tests. Results demonstrated that there was no statistically significant effect observed for reaction time, number of hits, or heart rate. Results suggest that MG-M imagery does not allow participants to react quicker to unpredictable stimuli, as participants could not generate unpredictable stimuli during imagery

    Cosmological Acceleration Through Transition to Constant Scalar Curvature

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    As shown by Parker and Raval, quantum field theory in curved spacetime gives a possible mechanism for explaining the observed recent acceleration of the universe. This mechanism, which differs in its dynamics from quintessence models, causes the universe to make a transition to an accelerating expansion in which the scalar curvature, R, of spacetime remains constant. This transition occurs despite the fact that we set the renormalized cosmological constant to zero. We show that this model agrees very well with the current observed type-Ia supernova (SNe-Ia) data. There are no free parameters in this fit, as the relevant observables are determined independently by means of the current cosmic microwave background radiation (CMBR) data. We also give the predicted curves for number count tests and for the ratio, w(z), of the dark energy pressure to its density, as well as for dw(z)/dz versus w(z). These curves differ significantly from those obtained from a cosmological constant, and will be tested by planned future observations.Comment: 31 pages, 7 figures; to appear in ApJ. Corrected numerical results; described quantum basis of theory; 18 references added; 2 figures adde

    Brief \u3cem\u3eAmicus Curiae\u3c/em\u3e of Environmental Defense Fund, National Audubon Society, National Wildlife Federation, Natural Resources Defense Council, Sierra Club, and Defenders of Wildlife, \u3cem\u3eTVA v. Hill\u3c/em\u3e, No. 76-1701

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    Brief for the respondents in the case of Tennessee Valley Authority v. Hiram G. Hill Jr., et al., heard by the United States Supreme Court in the October Term of 1977

    Aprendizagem pessoal e aprendizagem afastada : o caso do aluno de calculo

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    Orientadores: Vera Lucia Xavier Figueiredo, Anna Regina Lanner de MouraTese (doutorado) - Universidade Estadual de Campinas, Faculdade de EducaçãoDoutorad

    Distribution of the North American Porcupine (Erethizon dorsatum) in Northern California

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    Western Wildlife 4:17–28, 2017: The North American Porcupine (Erethizon dorsatum) is one of the most widely distributed mammals in North America, but recent reports have suggested declines in parts of its range in the West. In California, little is known about the historical or current status of the porcupine, and maps of its distribution conflict considerably. Nevertheless, the species is of interest to natural resource managers. For much of the 1900s, foresters and others primarily treated porcupines as pests because of the undesirable damage they inflict feeding on trees and gnawing on manmade items in search of salt. More recently, porcupines have been recognized for their role in promoting forest structure and diversity, and as potential prey for the Fisher (Pekania pennanti). We collected records of porcupine occurrence in the northern part of California since the beginning of the 20th Century, relying on government and private databases, reports from the public, and other sources. These records confirm that porcupines may occur in most major regions and habitat types across northern California, in contrast to many published range maps. The contemporary distribution of porcupines in the state most closely resembles the California Wildlife Habitat Relationships System (CWHR) range map, which is based on projections of suitable habitat. We are unable to offer deeper insight into trends of abundance and possible changes in distribution because these records are likely spatiotemporally correlated with observer effort. This work is a first step and we recommend that a broader statewide effort be conducted to better understand the distribution, abundance, and ecology of North American Porcupines in California. See below or click here to view data

    Draft genome sequences of four citrobacter isolates recovered from wild australian shorebirds

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    Citrobacter is a ubiquitous bacterial genus whose members inhabit a variety of niches. Some species are clinically important for both antimicrobial resistance (AMR) carriage and as the cause of nosocomial infections. Surveillance of Citrobacter species in the environment can provide indicators of the spread of AMR genes outside clinical spaces. In this study, we present draft genome sequences of four Citrobacter isolates obtained from three species of wild Australian shorebirds. Copyright © 2021 Smith et al. This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International license
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