179 research outputs found
Alien Registration- Sloat, Edith A. (Millinocket, Penobscot County)
https://digitalmaine.com/alien_docs/7281/thumbnail.jp
Pesquisa dos Modelos de Valor Adicionado (MVA) para as políticas de educação: Delimitação da discussão
In this manuscript, the guest editors of the EPAA Special Issue on “Value-Added Model (VAM) Research for Educational Policy” (1) introduce the background and policy context surrounding the increased use of VAMs for teacher evaluation and accountability purposes across the United States; (2) summarize the five research papers and one research-based commentary that were peer-reviewed and selected for inclusion in this special issue; and (3) discuss the relevance of the papers both individually and collectively. Their importance is discussed in terms of each paper’s contribution to the general research on this topic and each paper’s potential to inform educational policy. In addition, the papers reflect our shared thinking about VAMs, VAM output, and the inference-based decisions for which VAMs are increasingly being used.En este artículo, los editores invitados de este número especial de EPAA/AAPE sobre la investigación de los Modelos de Valor Agregado (MVA) para las políticas educativas: (1) presentan los antecedentes y el contexto político que rodean la utilización de MVA en la evaluación de los docentes y rendición de cuentas en los Estados Unidos, (2) un resumen de los cinco trabajos de investigación y el comentarios que fueron seleccionados para su inclusión en este número especial, y (3) analizamos la pertinencia de los documentos, tanto individual como colectivamente. Su importancia se discuten en términos de la contribución de cada documento para la investigación general sobre este tema y el potencial de cada artículo para informar la política educativa. Además, los documentos reflejan nuestro pensamiento sobre la producción de MVA y las decisiones basadas en MVA son cada vez más utilizados.Neste artigo, os editores convidados desta edição especial da EPAA/AAPE sobre a Pesquisa dos Modelos de Valor Adicionado (MVA) para as políticas de educação: (1) Apresentam o contexto político em torno do uso dos MVA na avaliação de professores e de responsabilização nos Estados Unidos, (2) um resumo dos cinco trabalhos de pesquisa e o comentário que foram selecionados para inclusão nesta edição especial, e (3) analisar a relevância dos trabalhos selecionados tanto individualmente como coletivamente. Sua importância é discutida em termos da contribuição de cada artigo para a pesquisa geral sobre este tema e as potencialidades de cada artigo para informar a política educacional. Além disso, os artigos refletem o nosso pensamento sobre a produção de decisões e MVA, e como são cada vez mais utilizados
Risk of Climate-Related Impacts on Global Rangelands – A Review and Modelling Study
Climate change threatens the ability of global rangelands to provide food, support livelihoods and deliver important ecosystems services. The extent and magnitude of potential impacts are however poorly understood. In this study, we review the risk of climate impacts along the rangeland systems food supply chain. We also present results from biophysical modelling simulations and spatial data analyses to identify where and to what extent rangelands may be at climatic risk. Although a quantification of the net impacts of climate change on rangeland production systems is beyond the reach of our current understanding, there is strong evidence that there will be impacts throughout the supply chain, from feed and animal production to processing, storage, transport, retailing and human consumption. Regarding grazing biomass production, this study finds that mean herbaceous biomass is projected to decrease across global rangelands between 2000 and 2050 under RCP 8.5 (-4.7%), while inter- (year-to-year) and intra- (month-to-month) annual variabilities are projected to increase (+21.3% and +8.2%, respectively). These averaged global estimates mask large spatial heterogeneities, with 74% of global rangeland area projected to experience a decline in mean biomass, 64% an increase in inter-annual variability and 54% an increase in intra-annual variability. The potentially most damaging vegetation trends for livestock production (i.e., simultaneous decreases in mean biomass and increases in inter-annual variability) are projected to occur in rangeland communities that are currently the most vulnerable (here, with the lowest livestock productivities and economic development levels and with the highest projected increases in human population densities). Large uncertainties remain as to climate futures and the exposure and responses of the interlinked human and natural systems to climatic changes over time. Consequently, adaptation choices will need to build on robust methods of designing, implementing and evaluating detailed development pathways, and account for a wide range of possible futures
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Influence of sex, migration distance, and latitude on life history expression in steelhead and rainbow trout (Oncorhynchus mykiss)
In partially migratory species, such as Oncorhynchus mykiss, the emergence of life history phenotypes is often attributed
to fitness trade-offs associated with growth and survival. Fitness trade-offs can be linked to reproductive tactics that vary between
the sexes, as well as the influence of environmental conditions. We found that O. mykiss outmigrants are more likely to be female
in nine populations throughout western North America (grand mean 65% female), in support of the hypothesis that anadromy
is more likely to benefit females. This bias was not related to migration distance or freshwater productivity, as indicated by
latitude. Within one O. mykiss population we also measured the resident sex ratio and did not observe a male bias, despite a high
female bias among outmigrants in that system. We provide a simulation to demonstrate the relationship between sex ratios and
the proportion of anadromy and show how sex ratios could be a valuable tool for predicting the prevalence of life history types
in a population
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Ecological and evolutionary patterns of freshwater maturation in Pacific and Atlantic salmonines
Reproductive tactics and migratory strategies in Pacific and Atlantic salmonines are inextricably linked through the effects of migration (or lack thereof) on age and size at maturity. In this review, we focus on the ecological and evolutionary patterns of freshwater maturation in salmonines, a key process resulting in the diversification of their life histories. We demonstrate that the energetics of maturation and reproduction provides a unifying theme for understanding both the proximate and ultimate causes of variation in reproductive schedules among species, populations, and the sexes. We use probabilistic maturation reaction norms to illustrate how variation in individual condition, in terms of body size, growth rate, and lipid storage, influences the timing of maturation. This useful framework integrates both genetic and environmental contributions to conditional strategies for maturation and, in doing so, demonstrates how flexible life histories can be both heritable and subject to strong environmental influences. We review evidence that the propensity for freshwater maturation in partially anadromous species is predictable across environmental gradients at geographic and local spatial scales. We note that growth is commonly associated with the propensity for freshwater maturation, but that life-history responses to changes in growth caused by temperature may be strikingly different than changes caused by differences in food availability. We conclude by exploring how contemporary management actions can constrain or promote the diversity of maturation phenotypes in Pacific and Atlantic salmonines and caution against underestimating the role of freshwater maturing forms in maintaining the resiliency of these iconic species.Keywords: Maturation, Salmon, Diversity, Salmo, Oncorhynchus, Oncorhynchus Resilience, Life history, Conservatio
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Downstream Warming and Headwater Acidity May Diminish Coldwater Habitat in Southern Appalachian Mountain Streams
Stream-dwelling species in the U.S. southern Appalachian Mountains region are particularly vulnerable to climate change and acidification. The objectives of this study were to quantify the spatial extent of contemporary suitable habitat for acid- and thermally sensitive aquatic species and to forecast future habitat loss resulting from expected temperature increases on national forest lands in the southern Appalachian Mountain region. The goal of this study was to help watershed managers identify and assess stream reaches that are potentially vulnerable to warming, acidification, or both. To our knowledge, these results represent the first regional assessment of aquatic habitat suitability with respect to the combined effects of stream water temperature and acid-base status in the United States. Statistical models were developed to predict July mean daily maximum water temperatures and air-water temperature relations to determine potential changes in future stream water temperatures. The length of stream considered suitable habitat for acid- and thermally sensitive species, based on temperature and acid neutralizing capacity thresholds of 20°C and 50 μeq/L, was variable throughout the national forests considered. Stream length displaying temperature above 20°C was generally more than five times greater than the length predicted to have acid neutralizing capacity below 50 μeq/L. It was uncommon for these two stressors to occur within the same stream segment. Results suggested that species’ distributional shifts to colder, higher elevation habitats under a warming climate can be constrained by acidification of headwater streams. The approach used in this study can be applied to evaluate climate change impacts to stream water resources in other regions
Biochemical adaptations of the retina and retinal pigment epithelium support a metabolic ecosystem in the vertebrate eye
Here we report multiple lines of evidence for a comprehensive model of energy metabolism in the vertebrate eye. Metabolic flux, locations of key enzymes, and our finding that glucose enters mouse and zebrafish retinas mostly through photoreceptors support a conceptually new model for retinal metabolism. In this model, glucose from the choroidal blood passes through the retinal pigment epithelium to the retina where photoreceptors convert it to lactate. Photoreceptors then export the lactate as fuel for the retinal pigment epithelium and for neighboring Mu ̈ ller glial cells. We used human retinal epithelial cells to show that lactate can suppress consumption of glucose by the retinal pigment epithelium. Suppression of glucose consumption in the retinal pigment epithelium can increase the amount of glucose that reaches the retina. This framework for understanding metabolic relationships in the vertebrate retina provides new insights into the underlying causes of retinal disease and age-related vision loss
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