9,770 research outputs found

    Re-evaluation of cosmic ray cutoff terminology

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    The study of cosmic ray access to locations inside the geomagnetic field has evolved in a manner that has led to some misunderstanding and misapplication of the terminology originally developed to describe particle access. This paper presents what is believed to be a useful set of definitions for cosmic ray cutoff terminology for use in theoretical and experimental cosmic ray studies

    Classical generalized constant coupling model for geometrically frustrated antiferromagnets

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    A generalized constant coupling approximation for classical geometrically frustrated antiferromagnets is presented. Starting from a frustrated unit we introduce the interactions with the surrounding units in terms of an internal effective field which is fixed by a self consistency condition. Results for the magnetic susceptibility and specific heat are compared with Monte Carlo data for the classical Heisenberg model for the pyrochlore and kagome lattices. The predictions for the susceptibility are found to be essentially exact, and the corresponding predictions for the specific heat are found to be in very good agreement with the Monte Carlo results.Comment: 4 pages, 3 figures, 2 columns. Discussion about the zero T value of the pyrochlore specific heat correcte

    Parallaxes of Five L Dwarfs with a Robotic Telescope

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    We report the parallax and proper motion of five L dwarfs obtained with observations from the robotic Liverpool Telescope. Our derived proper motions are consistent with published values and have considerably smaller errors. Based on our spectral type versus absolute magnitude diagram, we do not find any evidence for binaries among our sampleor, at least no comparable mass binaries. Their space velocities locate them within the thin disk, and based on the model comparisons, they have solar-like abundances. For all five objects, we derived effective temperature, luminosity, radius, gravity, and mass from an evolutionary model (CBA00) and our measured parallax; moreover, we derived their effective temperature by integrating observed optical and near-infrared spectra and model spectra (BSH06 or BT-Dusty) at longer wavelengths to obtain bolometric flux using the classical Stefan-Boltzmann law. Generally, the three temperatures for one object derived using two different methods with three models are consistent, although at lower temperature (e.g., for L4) the differences among the three temperatures are slightly larger than those at higher temperature (e.g., for L1).Peer reviewe

    What makes you not a Buddhist? : a preliminary mapping of values

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    This study sets out to establish which Buddhist values contrasted with or were shared by adolescents from a non-Buddhist population. A survey of attitude toward a variety of Buddhist values was fielded in a sample of 352 non-Buddhist schoolchildren aged between 13 and 15 in London. Buddhist values where attitudes were least positive concerned the worth of being a monk/nun or meditating, offering candles & incense on the Buddhist shrine, friendship on Sangha Day, avoiding drinking alcohol, seeing the world as empty or impermanent and Nirvana as the ultimate peace. Buddhist values most closely shared by non-Buddhists concerned the Law of Karma, calming the mind, respecting those deserving of respect, subjectivity of happiness, welfare work, looking after parents in old age and compassion to cuddly animals. Further significant differences of attitude toward Buddhism were found in partial correlations with the independent variables of sex, age and religious affiliation. Correlation patterns paralleled those previously described in theistic religions. Findings are applied to spiritual, moral, social and cultural development and for the teaching of religious to pupils of no faith adherence. The study recommends that quantitative psychometrics employed to conceptualize Buddhist values by discriminant validity in this study could be extended usefully to other aspects of the study of Buddhism, particularly in quest of validity in the conceptualization of Buddhist identity within specifically Buddhist populations

    Healthcare choice: Discourses, perceptions, experiences and practices

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    Policy discourse shaped by neoliberal ideology, with its emphasis on marketisation and competition, has highlighted the importance of choice in the context of healthcare and health systems globally. Yet, evidence about how so-called consumers perceive and experience healthcare choice is in short supply and limited to specific healthcare systems, primarily in the Global North. This special issue aims to explore how choice is perceived and utilised in the context of different systems of healthcare throughout the world, where choice, at least in policy and organisational terms, has been embedded for some time. The articles are divided into those emphasising: embodiment and the meaning of choice; social processes associated with choice; the uncertainties, risks and trust involved in making choices; and issues of access and inequality associated with enacting choice. These sociological studies reveal complexities not always captured in policy discourse and suggest that the commodification of healthcare is particularly problematic

    Strain induced half-metal to semiconductor transition in GdN

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    We have investigated the electronic structure and magnetic properties of GdN as a function of unit cell volume. Based on the first-principles calculations of GdN, we observe that there is a transformation in conduction properties associated with the volume increase: first from halfmetallic to semi-metallic, then ultimately to semiconducting. We show that applying stress can alter the carrier concentration as well as mobility of the holes and electrons in the majority spin channel. In addition, we found that the exchange parameters depend strongly on lattice constant, thus the Curie temperature of this system can be enhanced by applying stress or doping impurities.Comment: 9 pages, 3 figure

    Quantum generalized constant coupling model for geometrically frustrated antiferromagnets

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    A generalized constant coupling approximation for quantum geometrically frustrated antiferromagnets is presented. Starting from a frustrated unit, we introduce the interactions with the surrounding units in terms of an internal effective field which is fixed by a self consistency condition. Results for the static magnetic susceptibility and specific heat are compared with previous results in the framework of this same model for the classical limit. The range of applicability of the model is discussed.Comment: 11 pages, 6 figures, 1 Tables, typeset using RevTeX 4, small correction in Table

    Noves dades sobre el jaciment paleontològic de la cova de na Barxa

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    [spa] El yacimiento paleontológico de la Cova de na Barxa constituye la localidad-tipo de la especie Myotragus balearicus, pero sin embargo había permanecido prácticamente ignorado durante muchos años. La reciente catalogación y topografía de la cueva permitió reemprender su estudio paleontológico e iniciar un programa de dataciones radiométricas, mediante la técnica de las series de Uranio. Con su ayuda se ha podido demostrar la existencia de dos depósitos osíferos diferentes cuyos materiales fósiles, aunque lamentablemente escasos, presentan algunas características interesantes; incluyendo restos de Myotragus balearicus, Hypnornys morpheus, Nesiotites hidalgo, Alytes (Baleaphryne) muletensis y otros pequeños vertebrados. Como ambos depósitos osíferos se encuentran relacionados estratigráficamente con varias intercalaciones de coladas estalagmíticas, ha sido posible obtener informaciones cronológicas bastante precisas. La dataciones realizadas indican que el primer depósito osífero tiene una edad superior a 195.000 años, mientras que el segundo depósito osífero debe quedar comprendido entre los 11 9.000 años y los 7.500 años, según estimaciones fiables. En el presente trabajo se exponen los resultados de esta serie de investigaciones, todavía inéditas, incluyéndose la topografía y la descripción de la caverna.[eng] The palaeontological deposits of Cova de na Barxa (Capdepera, Mallorca) provide the type-locality of Myotragus balearicus, an endemic fossil mammal frequently found in Mallorcan cave deposits. This site has been ignored for a considerable time, but a new study has now been undertaken including the survey and description of the cave and its deposits. Stratigraphic correlation and uranium series analysis of flowstone layers has demonstrated that two separate ossiferous deposits are present. These both contain scarce remains of Myotragus balearicus, Hypnornys morpheus, Nesiotites hidalgo, Alytes (Baleaphryne) mule- tensis and other small vertebrates. Uranium series dating shows that the first ossiferous depo- sit is older than 195 ka, while the age of the second is between 119 ka and 7.5 ka

    Imaging stress and magnetism at high pressures using a nanoscale quantum sensor

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    Pressure alters the physical, chemical and electronic properties of matter. The development of the diamond anvil cell (DAC) enables tabletop experiments to investigate a diverse landscape of high-pressure phenomena ranging from the properties of planetary interiors to transitions between quantum mechanical phases. In this work, we introduce and utilize a novel nanoscale sensing platform, which integrates nitrogen-vacancy (NV) color centers directly into the culet (tip) of diamond anvils. We demonstrate the versatility of this platform by performing diffraction-limited imaging (~600 nm) of both stress fields and magnetism, up to pressures ~30 GPa and for temperatures ranging from 25-340 K. For the former, we quantify all six (normal and shear) stress components with accuracy <0.01<0.01 GPa, offering unique new capabilities for characterizing the strength and effective viscosity of solids and fluids under pressure. For the latter, we demonstrate vector magnetic field imaging with dipole accuracy <1011<10^{-11} emu, enabling us to measure the pressure-driven αϵ\alpha\leftrightarrow\epsilon phase transition in iron as well as the complex pressure-temperature phase diagram of gadolinium. In addition to DC vector magnetometry, we highlight a complementary NV-sensing modality using T1 noise spectroscopy; crucially, this demonstrates our ability to characterize phase transitions even in the absence of static magnetic signatures. By integrating an atomic-scale sensor directly into DACs, our platform enables the in situ imaging of elastic, electric and magnetic phenomena at high pressures.Comment: 18 + 50 pages, 4 + 19 figure
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