4,890 research outputs found

    Thermal simulation of magnetization reversals for size-distributed assemblies of core-shell exchange biased nanoparticles

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    A temperature dependent coherent magnetization reversal model is proposed for size-distributed assemblies of ferromagnetic nanoparticles and ferromagnetic-antiferromagnetic core-shell nanoparticles. The nanoparticles are assumed to be of uniaxial anisotropy and all aligned along their easy axis. The thermal dependence is included by considering thermal fluctuations, implemented via the N\'eel-Arrhenius theory. Thermal and angular dependence of magnetization reversal loops, coercive field and exchange-bias field are obtained, showing that F-AF size-distributed exchange-coupled nanoparticles exhibit temperature-dependent asymmetric magnetization reversal. Also, non-monotonic evolutions of He and Hc with T are demonstrated. The angular dependence of Hc with T exhibits a complex behavior, with the presence of an apex, whose position and amplitude are strongly T dependent. The angular dependence of He with T exhibits complex behaviors, which depends on the AF anisotropy and exchange coupling. The resulting angular behavior demonstrates the key role of the size distribution and temperature in the magnetic response of nanoparticles.Comment: Revised arguments in Introduction and last sectio

    A systems description of the national well-being system. Version 1.0

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    Policymakers are confronted with hard-to-address questions, such as ā€¢ What is the ultimate impact of very different policies on the well-being of citizens? ā€¢ How to anticipate, which policies will promote well-being the most and which ones will lead to tough trade-offs? ā€¢ How to focus scarce resources and maximize the positive impact on the well-being of citizens? Economic growth is ceasing down, and, moreover, in most of the developed countries additional growth does not promote the well-being of citizens as much as it used to. But what is well-being? According to a dictionary, well-being is a state of feeling happy, healthy or prosperous. In 1980s, a group of sociologists, philosophers and economists led by Amartya Sen and Martha Nussbaum suggested a framework to understand well-being beyond the economic indicators , such as the GDP. In fact, in the modern world, wellbeing itself becomes a prerequisite for economic growth and for social and economic stability. Governments begin to focus their attention directly on the multi-dimensional national well-being including and going beyond economic and material aspects. They look for new under-utilized resources that would raise the national well-being even despite weak economic growth. To discover effective and efficient solutions, one needs to maximize synergies and reduce losses from trade-offs . Systems analysis offers tools to do so. This challenge was presented to the International Institute for Applied Systems Analysis (IIASA) by the National Economic Council of Israel in 2018. In response, IIASA developed a pilot version of a systems description of the national well-being system that covers four major subsystems: economic subsystem, natural subsystem, human capacity subsystem, and social subsystem, each described by a set of indicators. This Working Paper presents the results of this pilot work. We rely on the OECD well-being framework as a basis to measure multi-dimensional well-being and work with 68 factors, of which 39 represent the OECD indicators. Based on evidence we collate from solid scientific literature, we connect these 68 factors by causal relationships and obtain a comprehensive systems map of the National Well-being System (NWS) (a causal loop diagram) comprising 208 directed links between factors. This systems map allows to trace all indirect effects and feedback loops between factors in a systematic fashion thus helping acquire a holistic understanding about the national well-being system. Empirical evidence clearly indicates that systems thinking is difficult to practice when causal interconnections become more complex, especially when it involves indirect effects and feedback loops. As a formal tool from qualitative systems analysis, our NWS map can assist policymakers to reveal trade-offs and synergies, reduce the problemā€™s ā€œwickednessā€ and discipline a dialogue. This version 1.0 can and should be developed further. This includes expert validation and fine-tuning, as well as customizing it to particular national and policy contexts. Eventually, our ambition is to develop a policy simulation tool that enables comparison of different policy options and their ultimate impact on well-being. We invite interested parties to join us in this endeavour

    A strategic framework to support the implementation of citizen science for environmental monitoring. Final report to SEPA

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    In this report we provide a decision framework that can be used to guide whether and when to use a citizen science approach for environmental monitoring. Before using the decision framework we recommend that five precursors to a citizen science approach are considered

    Choosing and using citizen science: a guide to when and how to use citizen science to monitor biodiversity and the environment

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    Here we aim to provide guidance to support people considering using a citizen science approach, especially (but not necessarily restricted to) monitoring biodiversity and the environment in the UK. It will help you decide whether citizen science is likely to be useful, and it will help you decide which broad approach to citizen science is most suitable for your question or activity. This guide does not cover the practical detail of developing a citizen science project. That information is provided in the ā€˜Guide to Citizen Scienceā€™ (Tweddle et al., 2012)

    Dark-Bright Solitons in Inhomogeneous Bose-Einstein Condensates

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    We investigate dark-bright vector solitary wave solutions to the coupled non-linear Schr\"odinger equations which describe an inhomogeneous two-species Bose-Einstein condensate. While these structures are well known in non-linear fiber optics, we show that spatial inhomogeneity strongly affects their motion, stability, and interaction, and that current technology suffices for their creation and control in ultracold trapped gases. The effects of controllably different interparticle scattering lengths, and stability against three-dimensional deformations, are also examined.Comment: 5 pages, 5 figure

    Als3 is a Candida albicans invasin that binds to cadherins and induces endocytosis by host cells.

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    Candida albicans is the most common cause of hematogenously disseminated and oropharyngeal candidiasis. Both of these diseases are characterized by fungal invasion of host cells. Previously, we have found that C. albicans hyphae invade endothelial cells and oral epithelial cells in vitro by inducing their own endocytosis. Therefore, we set out to identify the fungal surface protein and host cell receptors that mediate this process. We found that the C. albicans Als3 is required for the organism to be endocytosed by human umbilical vein endothelial cells and two different human oral epithelial lines. Affinity purification experiments with wild-type and an als3delta/als3delta mutant strain of C. albicans demonstrated that Als3 was required for C. albicans to bind to multiple host cell surface proteins, including N-cadherin on endothelial cells and E-cadherin on oral epithelial cells. Furthermore, latex beads coated with the recombinant N-terminal portion of Als3 were endocytosed by Chinese hamster ovary cells expressing human N-cadherin or E-cadherin, whereas control beads coated with bovine serum albumin were not. Molecular modeling of the interactions of the N-terminal region of Als3 with the ectodomains of N-cadherin and E-cadherin indicated that the binding parameters of Als3 to either cadherin are similar to those of cadherin-cadherin binding. Therefore, Als3 is a fungal invasin that mimics host cell cadherins and induces endocytosis by binding to N-cadherin on endothelial cells and E-cadherin on oral epithelial cells. These results uncover the first known fungal invasin and provide evidence that C. albicans Als3 is a molecular mimic of human cadherins

    Phase sensitive detection of dipole radiation in a fiber-based high numerical aperture optical system

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    We theoretically study the problem of detecting dipole radiation in an optical system of high numerical aperture in which the detector is sensitive to \textit{field amplitude}. In particular, we model the phase sensitive detector as a single-mode cylindrical optical fiber. We find that the maximum in collection efficiency of the dipole radiation does not coincide with the optimum resolution for the light gathering instrument. The calculated results are important for analyzing fiber-based confocal microscope performance in fluorescence and spectroscopic studies of single molecules and/or quantum dots.Comment: 12 pages, 2 figure

    Spermidine/spermine N1-acetyltransferase specifically binds to the integrin Ī±9 subunit cytoplasmic domain and enhances cell migration

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    The integrin Ī±9Ī²1 is expressed on migrating cells, such as leukocytes, and binds to multiple ligands that are present at sites of tissue injury and inflammation. Ī±9Ī²1, like the structurally related integrin Ī±4Ī²1, mediates accelerated cell migration, an effect that depends on the Ī±9 cytoplasmic domain. Ī±4Ī²1 enhances migration through reversible binding to the adapter protein, paxillin, but Ī±9Ī²1-dependent migration is paxillin independent. Using yeast two-hybrid screening, we identified the polyamine catabolizing enzyme spermidine/spermine N1-acetyltransferase (SSAT) as a specific binding partner of the Ī±9 cytoplasmic domain. Overexpression of SSAT increased Ī±9Ī²1-mediated migration, and small interfering RNA knockdown of SSAT inhibited this migration without affecting cell adhesion or migration that was mediated by other integrin cytoplasmic domains. The enzyme activity of SSAT is critical for this effect, because a catalytically inactive version did not enhance migration. We conclude that SSAT directly binds to the Ī±9 cytoplasmic domain and mediates Ī±9-dependent enhancement of cell migration, presumably by localized effects on acetylation of polyamines or of unidentified substrates

    The Glenburgh Orogeny as a record of Paleoproterozoic continent-continent collision

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    The Gascoyne Province lies at the western end of the Capricorn Orogen, and includes a range of Paleoproterozoic gneisses and metasedimentary basins, known as the Glenburgh Terrane, that are exotic to both the Yilgarn and Pilbara Cratons. Here we present sensitive high-resolution ion microprobe (SHRIMP) Uā€“Pb ages for a variety of detrital zircons and metamorphic zircon and monazite from several of these pre-collisional siliciclastic basins that were deformed and metamorphosed at high metamorphic grade during the Glenburgh Orogeny, when the Yilgarn Craton collided with a previously assembled Pilbara Craton ā€“ Glenburgh Terrane. The precursors to the Moogie Metamorphics were deposited sometime between 2240 and 2125 Ma in either a foreland basin to the Ophthalmian Orogeny, or a retro-arc that formed during the collision of the Glenburgh Terrane with the Pilbara Craton. The Quartpot Pelite of the Camel Hills Metamorphics was deposited between 2000 Ma and 1985 Ma as a fore-arc deposit to the Dalgaringa continental margin arc. The Petter Calc-silicate of the Camel Hills Metamorphics was deposited sometime between 2610 and 1965 Ma as part of the Yilgarn Craton passive margin. Metamorphic zircon and monazite ages indicate that continental collision and high-grade metamorphism during the Glenburgh Orogeny (D2g) took place between 1965 Ma and 1950 Ma
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