1,019 research outputs found

    Positive operator valued measures covariant with respect to an irreducible representation

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    Given an irreducible representation of a group G, we show that all the covariant positive operator valued measures based on G/Z, where Z is a central subgroup, are described by trace class, trace one positive operators.Comment: 9 pages, Latex2

    Mirror displacement energies and neutron skins

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    A gross estimate of the neutron skin [0.80(5)(N−Z)/A(N-Z)/A fm] is extracted from experimental proton radii, represented by a four parameter fit, and observed mirror displacement energies (CDE). The calculation of the latter relies on an accurately derived Coulomb energy and smooth averages of the charge symmetry breaking potentials constrained to state of the art values. The only free parameter is the neutron skin itself. The Nolen Schiffer anomaly is reduced to small deviations (rms=127 keV) that exhibit a secular trend. It is argued that with state of the art shell model calculations the anomaly should disappear. Highly accurate fits to proton radii emerge as a fringe benefit.Comment: 4 pages 3 figures, superseeds first part of nucl-th/0104048 Present is new extended version: 5 pages 4 figures. Explains more clearly the achievements of the previous on

    Indoor air pollution, health and economic well-being

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    Abstract. Indoor air pollution (IAP) caused by solid fuel use and/or traditional cooking stoves is a global health threat, particularly for women and young children. The WHO World Health Report 2002 estimates that IAP is responsible for 2.7% of the loss of disability adjusted life years (DALYs) worldwide and 3.7% in highmortality developing countries. Despite the magnitude of this problem, social scientists have only recently begun to pay closer attention to this issue and to test strategies for reducing IAP. In this paper, we provide a survey of the current literature on the relationship between indoor air pollution, respiratory health and economic well-being. We then discuss the available evidence on the effectiveness of popular policy prescriptions to reduce IAP within the household

    Three-body monopole corrections to the realistic interactions

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    It is shown that a very simple three-body monopole term can solve practically all the spectroscopic problems--in the pp, sdsd and pfpf shells--that were hitherto assumed to need drastic revisions of the realistic potentials.Comment: 4 pages, 5figure

    Shell Model Description of Isotope Shifts in Calcium

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    Isotope shifts in the nuclear charge radius of even and odd calcium isotopes are calculated within the nuclear shell model. The model space includes all configurations of nucleons in the 2s,1d3/2,1f7/2,and 2p3/22s, 1d_{3/2}, 1f_{7/2}, {\rm and} ~2p_{3/2} orbits. The shell model describes well the energies of the intruder states in Sc and Ca, as well as the energies of the low-lying 2+2^+ and 3−3^- states in the even Ca isotopes. The characteristic features of the isotope shifts, the parabolic dependence on AA and the prominent odd-even staggering, are well reproduced by the model. These features are related to the partial breakdown of the Z=20Z = 20 shell closure caused by promotion, due to the neutron-proton interaction, of the dsds shell protons into the fpfp shell.Comment: 4 pages, 4 figures include

    Preferences and skills of Indian public sector teachers

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    With a sample of 700 future public sector primary teachers in India, a Discrete Choice Experiment is used to measure job preferences, particularly regarding location. General skills are also tested. Urban origin teachers and women are more averse to remote locations than rural origin teachers and men respectively. Women would require a 26-73 percent increase in salary for moving to a remote location. The results suggest that existing caste and gender quotas can be detrimental for hiring skilled teachers willing to work in remote locations. The most preferred location is home, which supports decentralised hiring, although this could compromise skills

    Full 0ℏω0\hbar\omega shell model calculation of the binding energies of the 1f7/21f_{7/2} nuclei

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    Binding energies and other global properties of nuclei in the middle of the pfpf shell, such as M1, E2 and Gamow-Teller sum rules, have been obtained using a new Shell Model code (NATHAN) written in quasi-spin formalism and using a j−jj-j-coupled basis. An extensive comparison is made with the recently available Shell Model Monte Carlo results using the effective interaction KB3. The binding energies for -nearly- all the 1f7/21f_{7/2} nuclei are compared with the measured (and extrapolated) results.Comment: 7 page

    What’s on trial? The making of field experiments in international development

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    In the last 20 years, the drive for evidence‐based policymaking has been coupled with a concurrent push for the use of randomized controlled trials (RCTs) as the “gold‐standard” for generating rigorous evidence on whether or not development interventions work. Drawing on content analysis of 63 development RCTs and 4 years of participant observation, I provide a rich description of the diverse set of actors and the transnational organizational effort required to implement development RCTs and maintain their “scientific status.” Particularly, I investigate the boundary work that proponents of RCTs—also known as randomistas—do to differentiate the purposes and merits of testing development projects from doing them, as a way to bypass the political and ethical problems presented by adopting the experimental method with foreign aid beneficiaries in poor countries. Although randomistas have been mostly successful in differentiating RCTs from the projects evaluated, I also examine cases where they were not able to do so, as a means to highlight the controversies associated with implementing RCTs in international development.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/154964/1/bjos12723_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154964/2/bjos12723.pd

    Syzygies in equivariant cohomology for non-abelian Lie groups

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    We extend the work of Allday-Franz-Puppe on syzygies in equivariant cohomology from tori to arbitrary compact connected Lie groups G. In particular, we show that for a compact orientable G-manifold X the analogue of the Chang-Skjelbred sequence is exact if and only if the equivariant cohomology of X is reflexive, if and only if the equivariant Poincare pairing for X is perfect. Along the way we establish that the equivariant cohomology modules arising from the orbit filtration of X are Cohen-Macaulay. We allow singular spaces and introduce a Cartan model for their equivariant cohomology. We also develop a criterion for the finiteness of the number of infinitesimal orbit types of a G-manifold.Comment: 28 pages; minor change
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