20,808 research outputs found

    <i>Aporosa</i> Blume from the paleoequatorial rainforest of Bikaner, India: Its evolution and diversification in deep time

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    The Gondwanan origin, northward migration and subsequent collision with Asia means that the Indian subcontinent is of particular interest regarding the origin and dispersal of numerous plants and animal species. With this in mind, we describe a fossil leaf of Aporosa Blume (Phyllanthaceae) from the Paleogene of the Indian subcontinent and discuss its evolution and diversification with respect to the moving Indian plate and its connection with Southeast Asia since the early Cenozoic. At present, Aporosa Blume is confined to Southeast Asia with a few species in India and New Guinea. It is represented by six endemic species growing in the evergreen forests of India and Sri Lanka, including Aporosa acuminata Thwaites, which is morphologically close to the here described fossil from Bikaner, Rajasthan, India. From the age of the fossil and the distribution of its modern comparable form, it is assumed that Aporosa originated on the Indian subcontinent and then was distributed to Southeast Asia, supporting the ‘Out of India’ hypothesis. Diversification of the genus might have taken place either in the Paleogene or Neogene. Our fossil leaf material also indicates the existence of palaeoequatorial (< 10° N) tropical rain forests in western India during the Paleogene in contrast to dry and desertic climate occurring today

    Public Policy and Social Good: Theory, Practice and Beyond

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    In this paper I argue that the most fundamental goal of any public policy is to assist the realization of social good. I take it that the idea of social good has developed differently in different political and moral traditions, and focus my analysis on the interplay of liberalism, virtue ethics and the Capability Approach. I argue that the liberal conception of social good, as espoused by its leading exponents, is somewhat problematic, and that it fails to account for meaningful civic associations. Even though liberal thinkers often prioritize an individual’s freedom and autonomy, they do not provide us with concreto principles that can facilitate the realization of these goals. I draw upon the practical functioning of leading liberal democracies, including the United States, Canada and India, emphasizing the role of normative political constraints in policy making. I conclude that the liberal conception of social good stands in an acute need of a fresh principle that can rectify the above anomalies and reinvigorate its moral force, and that such a principle can probably be constructed with the help of Amartya Sen’s Capability Approach and Aristotle’s Virtue Theory.The “Annales. Ethics in Economic Life” is affiliated and co-financed by the Faculty of Economics and Sociology of the University of Lodz

    Exact Solution of Return Hysteresis Loops in One Dimensional Random Field Ising Model at Zero Temperature

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    Minor hysteresis loops within the main loop are obtained analytically and exactly in the one-dimensional ferromagnetic random field Ising-model at zero temperature. Numerical simulations of the model show excellent agreement with the analytical results

    Attractive Potential around a Thermionically Emitting Microparticle

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    We present a simulation study of the charging of a dust grain immersed in a plasma, considering the effect of electron emission from the grain (thermionic effect). It is shown that the OML theory is no longer reliable when electron emission becomes large: screening can no longer be treated within the Debye-Huckel approach and an attractive potential well forms, leading to the possibility of attractive forces on other grains with the same polarity. We suggest to perform laboratory experiments where emitting dust grains could be used to create non-conventional dust crystals or macro-molecules.Comment: 3 figures. To appear on Physical Review Letter

    Return to return point memory

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    We describe a new class of systems exhibiting return point memory (RPM) that are different from those discussed before in the context of ferromagnets. We show numerically that one dimensional random Ising antiferromagnets have RPM, when configurations evolve from a large field. However, RPM is violated when started from some stable configurations at finite field unlike in the ferromagnetic case. This implies that the standard approach to understanding ferromagnetic RPM systems will fail for this case. We also demonstrate RPM with a set of variables that keep track of spin flips at each site. Conventional RPM for the spin configuration is a projection of this result, suggesting that spin flip variables might be a more fundamental representation of the dynamics. We also present a mapping that embeds the antiferromagnetic chain in a two dimensional ferromagnetic model, and prove RPM for spin exchange dynamics in the interior of the chain with this mapping

    Discriminating between L\"uders and von Neumann measuring devices: An NMR investigation

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    Measurement of an observable on a quantum system involves a probabilistic collapse of the quantum state and a corresponding measurement outcome. L\"uders and von Neumann state update rules attempt to describe the above phenomenological observations. These rules are identical for a nondegenerate observable, but differ for a degenerate observable. While L\"uders rule preserves superpositions within a degenerate subspace under a measurement of the corresponding degenerate observable, the von Neumann rule does not. Recently Hegerfeldt and Mayato [Phys. Rev. A, 85, 032116 (2012)] had formulated a protocol to discriminate between the two types of measuring devices. Here we have reformulated this protocol for quantum registers comprising of system and ancilla qubits. We then experimentally investigated this protocol using nulear spin systems with the help of NMR techniques, and found that L\"uders rule is favoured.Comment: 6 pages,6 figures, updated with a few more calculation

    Influence of Ni doping on the electronic structure of Ni_2MnGa

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    The modifications in the electronic structure of Ni_{2+x}Mn_{1-x}Ga by Ni doping have been studied using full potential linearized augmented plane wave method and ultra-violet photoemission spectroscopy. Ni 3d related electron states appear due to formation of Ni clusters. We show the possibility of changing the minority-spin DOS with Ni doping, while the majority-spin DOS remains almost unchanged. The total magnetic moment decreases with excess Ni. The total energy calculations corroborate the experimentally reported changes in the Curie temperature and the martensitic transition temperature with x.Comment: 4 pages, 4 figures, accepted in Phys. Rev.
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