2,272 research outputs found

    C.I.A.: College (In)Action: An Observation of the Female College Experience.

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    A film that I have written and directed about females in college and what they experience in one academic year based on the experiences of my friends and myself

    Berry's phase in noncommutative spaces

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    We introduce the perturbative aspects of noncommutative quantum mechanics. Then we study the Berry's phase in the framework of noncommutative quantum mechanics. The results show deviations from the usual quantum mechanics which depend on the parameter of space/space noncommtativity.Comment: 7 pages, no figur

    Influence of Charge Order on the Ground States of TMTTF Molecular Salts

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    (TMTTF)2AsF6 and (TMTTF)2SbF6 are both known to undergo a charge ordering phase transition, though their ground states are different. The ground state of the first is Spin-Peierls, and the second is an antiferromagnet. We study the effect of pressure on the ground states and the charge-ordering using 13C NMR spectroscopy. The experiments demonstrate that the the CO and SP order parameters are repulsive, and consequently the AF state is stabilized when the CO order parameter is large, as it is for (TMTTF)2SbF6. An extension of the well-known temperature/pressure phase diagram is proposed.Comment: 5pages, 5 figures, Proceeding of ISCOM2003, to appear in Journal de Physique I

    Semileptonic decays of baryons in a relativistic quark model

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    We calculate semileptonic decays of light and heavy baryons in a relativistically covariant constituent quark model. The model is based on the Bethe-Salpeter-equation in instantaneous approximation. It generates satisfactory mass spectra for mesons and baryons up to the highest observable energies. Without introducing additional free parameters we compute on this basis helicity amplitudes of electronic and muonic semileptonic decays of baryons. We thus obtain form factor ratios and decay rates in good agreement with experiment.Comment: 8 pages, 10 figures, 2 tables, typos remove

    NMR evidence for very slow carrier density fluctuations in the organic metal (TMTSF)2_2ClO4_4

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    We have investigated the origin of the large increase in spin-echo decay rates for the 77^{77}Se nuclear spins at temperatures near to T=30KT=30K in the organic superconductor (TMTSF)2_2ClO4_4. The measured angular dependence of T21T_2^{-1} demonstrates that the source of the spin-echo decays lies with carrier density fluctuations rather than fluctuations in TMTSF molecular orientation. The very long time scales are directly associated with the dynamics of the anion ordering occurring at T=25KT=25K, and the inhomogeneously broadened spectra at lower temperatures result from finite domain sizes. Our results are similar to observations of line-broadening effects associated with charge-ordering transitions in quasi-two dimensional organic conductors.Comment: 5 pages, 4 figure

    Heisenberg quantization for the systems of identical particles and the Pauli exclusion principle in noncommutative spaces

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    We study the Heisenberg quantization for the systems of identical particles in noncommtative spaces. We get fermions and bosons as a special cases of our argument, in the same way as commutative case and therefore we conclude that the Pauli exclusion principle is also valid in noncommutative spaces.Comment: 8 pages, 1 figur

    Suicide Prevention and Follow-Up Services: A Narrative Review

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    Previous suicide attempt is the most important predictor of death by suicide. Thus preventive interventions after attempting to suicide is essential to prevent reattempts. This paper attempts to determine whether phone preventive interventions or other vehicles (postal cards, email and case management) are effective in reattempt prevention and health promotion after discharge by providing an overview of studies on suicide reattempts. The research investigated in this review conducted from 1995 to 2014. A total of 26 cases related to the aim of this research were derived from 36 English articles with the aforementioned keywords Research shows that providing comprehensive aids, social support, and follow-up after discharge can significantly prevent suicide reattempts. Several studies showed that follow-up support (phone calls, crisis cards, mails, postal cards.) after discharge can significantly decrease the risk of suicide. More randomized controlled trials (RCT) are required to determine what factors of follow-up are more effective than other methods

    Groundwater augmentation through the site selection of floodwater spreading using a data mining approach (case study: Mashhad Plain, Iran)

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    © 2018 by the authors. It is a well-known fact that sustainable development goals are difficult to achieve without a proper water resources management strategy. This study tries to implement some state-of-the-art statistical and data mining models i.e., weights-of-evidence (WoE), boosted regression trees (BRT), and classification and regression tree (CART) to identify suitable areas for artificial recharge through floodwater spreading (FWS). At first, suitable areas for the FWS project were identified in a basin in north-eastern Iran based on the national guidelines and a literature survey. Using the same methodology, an identical number of FWS unsuitable areas were also determined. Afterward, a set of different FWS conditioning factors were selected for modeling FWS suitability. The models were applied using 70% of the suitable and unsuitable locations and validated with the rest of the input data (i.e., 30%). Finally, a receiver operating characteristics (ROC) curve was plotted to compare the produced FWS suitability maps. The findings depicted acceptable performance of the BRT, CART, and WoE for FWS suitability mapping with an area under the ROC curves of 92, 87.5, and 81.6%, respectively. Among the considered variables, transmissivity, distance from rivers, aquifer thickness, and electrical conductivity were determined as the most important contributors in the modeling. FWS suitability maps produced by the proposed method in this study could be used as a guideline for water resource managers to control flood damage and obtain new sources of groundwater. This methodology could be easily replicated to produce FWS suitability maps in other regions with similar hydrogeological conditions

    Noncommutative fluid dynamics in the Snyder space-time

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    In this paper, we construct for the first time the non-commutative fluid with the deformed Poincare invariance. To this end, the realization formalism of the noncommutative spaces is employed and the results are particularized to the Snyder space. The non-commutative fluid generalizes the fluid model in the action functional formulation to the noncommutative space. The fluid equations of motion and the conserved energy-momentum tensor are obtained.Comment: 12 pages. Version published by Phys. Rev.
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