236 research outputs found

    Habitat Selection of Shrubland Birds in the Great Lakes Plains Region of New York State

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    Over the course of the last century, shrubland habitat in the northeastern United States has declined due to farmland abandonment, deforestation, reforestation, human population growth and increased anthropogenic efforts to limit natural disturbances. In turn, these landscape alterations have caused a decline in the shrubland guild of birds in the northeastern United States, specifically the Great Lakes Plain Region. Declines have been so significant that wildlife managers must actively conserve existing shrublands and create new habitat to support shrubland birds. Thus, to offer suggestions for conservation and management of shrubland habitats and the birds that rely on them, I studied shrubland birds and their associated habitats in the Great Lakes Plains Region over two breeding periods in 2006 and 2007. My results revealed few consistent patterns in the bird habitat models developed from my data. This was not surprising, as most areas studied drastically varied in both vegetation community structure and composition. In addition, shrubland birds are often characterized by broad habitat preferences. Thus, the majority of the results can best be examined on a site-specific and species-specific basis. Some habitat variables did stand out in the models. Shrub hit diversity seemed to be an important predictor of shrubland bird abundance. Shrubland area also came up as a significant variable in a number of bird-habitat models. Even with the lack of consistency among my models, my data, along with other research, yielded management recommendations that should increase shrubland habitat, which should benefit shrubland birds. There are four main characteristics of shrubland habitat that need to be considered in order to increase and sustain declining species of shrubland birds: (1) shrublands should be relatively large (\u3e0.6 ha) in area, regardless of area-sensitivity (or lack-there-of) of shrubland birds; (2) shrublands should be adjacent or near other shrubland sites in order to avoid displacement of shrubland and forest birds; (3) shrublands need to be reasonably accessible to brush hogs and tractors so that they can be maintained without issue; and (4) shrublands should be created and/or maintained from existing shrublands, grasslands, or old fields, as shrublands converted from forest habitats are often of poor quality. When looking at the big picture of shrub land management, there is no one management practice that is best. Thus, management should be adaptive so that practices can be changed when new data becomes available, without compromising explicit management and conservation goals

    Interplay Between Yu-Shiba-Rusinov States and Multiple Andreev Reflections

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    Motivated by recent scanning tunneling microscopy experiments on single magnetic impurities on superconducting surfaces, we present here a comprehensive theoretical study of the interplay between Yu-Shiba-Rusinov bound states and (multiple) Andreev reflections. Our theory is based on a combination of an Anderson model with broken spin degeneracy and nonequilibrium Green's function techniques that allows us to describe the electronic transport through a magnetic impurity coupled to superconducting leads for arbitrary junction transparency. Using this combination we are able to elucidate the different tunneling processes that give a significant contribution to the subgap transport. In particular, we predict the occurrence of a large variety of Andreev reflections mediated by Yu-Shiba-Rusinov bound states that clearly differ from the standard Andreev processes in non-magnetic systems. Moreover, we provide concrete guidelines on how to experimentally identify the subgap features originating from these tunneling events. Overall, our work provides new insight into the role of the spin degree of freedom in Andreev transport physics.Comment: 15 pages, 10 figure

    Tunneling processes between Yu-Shiba-Rusinov bound states

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    Very recent experiments have reported the tunneling between Yu-Shiba-Rusinov (YSR) bound states at the atomic scale. These experiments have been realized with the help of a scanning tunneling microscope where a superconducting tip is functionalized with a magnetic impurity and is used to probe another magnetic impurity deposited on a superconducting substrate. In this way it has become possible to study for the first time the spin-dependent transport between individual superconducting bound states. Motivated by these experiments, we present here a comprehensive theoretical study of the tunneling processes between YSR bound states in a system in which two magnetic impurities are coupled to superconducting leads. Our theory is based on a combination of an Anderson model with broken spin degeneracy to describe the impurities and nonequilibrium Green's function techniques to compute the current-voltage characteristics. This combination allows us to describe the spin-dependent transport for an arbitrary strength of the tunnel coupling between the impurities. We first focus on the tunnel regime and show that our theory naturally explains the experimental observations of the appearance of current peaks in the subgap region due to both the direct and thermal tunneling between the YSR states in both impurities. Then, we study in detail the case of junctions with increasing transparency, which has not been experimentally explored yet, and predict the occurrence of a large variety of (multiple) Andreev reflections mediated by YSR states that give rise to a very rich structure in the subgap current. In particular, we predict the occurrence of multiple Andreev reflections that involve YSR states in different impurities. These processes have no analogue in single-impurity junctions and they are manifested as current peaks with negative differential conductance for subgap voltages.Comment: 16 pages, 9 figures. arXiv admin note: text overlap with arXiv:2005.0649

    The capabilities approach and critical social policy: lessons from the majority world?

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    The capabilities approach (CA) most closely associated with the thinner and thicker versions of Sen and Nussbaum has the potential to provide a paradigm shift for critical social policy, encompassing but also transcending some of the limitations associated with the Marshallian social citizenship approach. The article argues, however, that it cannot simply be imported from the majority world, rather there is a need to bear in mind the critical literature that developed around it. This is generally discussed and then critically applied to case studies of CA in the developed capitalist world, particularly the Equalities Review conducted for the Equality and Human Rights Commission

    State education as high-yield investment: human capital theory in European policy discourse

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    Human Capital Theory has been an increasingly important phenomenon in economic thought over the last 50 years. The central role it affords to education has become even more marked in recent years as the concept of the ‘knowledge economy’ has become a global concern. In this paper, the prevalence of Human Capital Theory within European educational policy discourse is explored. The paper examines a selection of policy documents from a number of disparate European national contexts and considers the extent to which the ideas of Human Capital Theory can be seen to be influential. In the second part of the paper, the implications of Human Capital Theory for education are considered, with a particular focus on the possible ramifications at a time of economic austerity. The paper argues that Human Capital Theory risks offering a diminished view of the person, a diminished view of education, but that with its sole focus on economic goals leaves room for educationists and others to argue for the educational, social, and moral values it ignores, and for the conception of the good life and good society it fails to mention

    Ocean model resolution dependence of Caribbean sea-level projections

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    Abstract Sea-level rise poses severe threats to coastal and low-lying regions around the world, by exacerbating coastal erosion and flooding. Adequate sea-level projections over the next decades are important for both decision making and for the development of successful adaptation strategies in these coastal and low-lying regions to climate change. Ocean components of climate models used in the most recent sea-level projections do not explicitly resolve ocean mesoscale processes. Only a few effects of these mesoscale processes are represented in these models, which leads to errors in the simulated properties of the ocean circulation that affect sea-level projections. Using the Caribbean Sea as an example region, we demonstrate a strong dependence of future sea-level change on ocean model resolution in simulations with a global climate model. The results indicate that, at least for the Caribbean Sea, adequate regional projections of sea-level change can only be obtained with ocean models which capture mesoscale processes.info:eu-repo/semantics/publishe

    Tropical biogeomorphic seagrass landscapes for coastal protection:Persistence and wave attenuation during major storms events

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    The intensity of major storm events generated within the Atlantic Basin is projected to rise with the warming of the oceans, which is likely to exacerbate coastal erosion. Nature-based flood defence has been proposed as a sustainable and effective solution to protect coastlines. However, the ability of natural ecosystems to withstand major storms like tropical hurricanes has yet to be thoroughly tested. Seagrass meadows both stabilise sediment and attenuate waves, providing effective coastal protection services for sandy beaches. To examine the tolerance of Caribbean seagrass meadows to extreme storm events, and to investigate the extent of protection they deliver to beaches, we employed a combination of field surveys, biomechanical measurements and wave modelling simulations. Field surveys of sea- grass meadows before and after a direct hit by the category 5 Hurricane Irma documented that estab- lished seagrass meadows of Thalassia testudinum re- mained unaltered after the extreme storm event. The flexible leaves and thalli of seagrass and calci- fying macroalgae inhabiting the meadows were shown to sustain the wave forces that they are likely to experience during hurricanes. In addition, the seagrass canopy and the complex biogeomorphic landscape built by the seagrass meadows combine to significantly dissipate extreme wave forces, ensuring that erosion is minimised within sandy beach fore- shores. The persistence of the Caribbean seagrass meadows and their coastal protection services dur- ing extreme storm events ensures that a stable coastal ecosystem and beach foreshore is maintained in tropical regions

    A Large Hadron Electron Collider at CERN

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    This document provides a brief overview of the recently published report on the design of the Large Hadron Electron Collider (LHeC), which comprises its physics programme, accelerator physics, technology and main detector concepts. The LHeC exploits and develops challenging, though principally existing, accelerator and detector technologies. This summary is complemented by brief illustrations of some of the highlights of the physics programme, which relies on a vastly extended kinematic range, luminosity and unprecedented precision in deep inelastic scattering. Illustrations are provided regarding high precision QCD, new physics (Higgs, SUSY) and electron-ion physics. The LHeC is designed to run synchronously with the LHC in the twenties and to achieve an integrated luminosity of O(100) fb−1^{-1}. It will become the cleanest high resolution microscope of mankind and will substantially extend as well as complement the investigation of the physics of the TeV energy scale, which has been enabled by the LHC
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