24,785 research outputs found

    Elastic and inelastic breakup of deuterons with energy below 100 MeV

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    We present calculations of deuteron elastic and inelastic breakup cross sections and angular distributions at deuteron energies below 100 MeV obtained using the post-form DWBA approximation. The elastic breakup cross section was extensively studied in the past. Very few calculations of inelastic breakup have been performed, however. We also analyze the angular momentum - energy distributions of the cross section for formation of the compound nucleus after inelastic breakup.Comment: 7 page

    Relationship between antihypertensive medications and cognitive impairment: Part II. Review of Physiology and animal studies

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    Purpose of Review There is an established association between hypertension and increased risk of poor cognitive performance and dementia including Alzheimer’s disease; however, associations between antihypertensive medications (AHM) and dementia risk are less clear. An increased interest in AHM has resulted in expanding publications; however, none of the recent reviews provide comprehensive review. Our extensive review includes 24 mechanistic animal and human studies published over the last 5 years assessing relationship between AHM and cognitive function. Recent Findings All classes of AHM showed similar result patterns in animal studies. The mechanism by which AHM exert their effect was extensively studied by evaluating well-established pathways of AD disease process, including amyloid beta (Aβ), vascular, oxidative stress and inflammation pathways, but only few studies evaluated the blood pressure lowering effect on the AD disease process. Summary Methodological limitations of the studies prevent comprehensive conclusions prior to further work evaluating AHM in animals and larger human observational studies, and selecting those with promising results for future RCTs

    Statistical multifragmentation model with discretized energy and the generalized Fermi breakup. I. Formulation of the model

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    The Generalized Fermi Breakup recently demonstrated to be formally equivalent to the Statistical Multifragmentation Model, if the contribution of excited states are included in the state densities of the former, is implemented. Since this treatment requires the application of the Statistical Multifragmentation Model repeatedly on the hot fragments until they have decayed to their ground states, it becomes extremely computational demanding, making its application to the systems of interest extremely difficult. Based on exact recursion formulae previously developed by Chase and Mekjian to calculate the statistical weights very efficiently, we present an implementation which is efficient enough to allow it to be applied to large systems at high excitation energies. Comparison with the GEMINI++ sequential decay code shows that the predictions obtained with our treatment are fairly similar to those obtained with this more traditional model.Comment: 8 pages, 6 figure

    Prospects for a mHz-linewidth laser

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    We propose a new light source based on having alkaline-earth atoms in an optical lattice collectively emit photons on an ultra-narrow clock transition into the mode of a high Q-resonator. The resultant optical radiation has an extremely narrow linewidth in the mHz range, even smaller than that of the clock transition itself due to collective effects. A power level of order 1012W10^{-12}W is possible, sufficient for phase-locking a slave optical local oscillator. Realizing this light source has the potential to improve the stability of the best clocks by two orders of magnitude.Comment: minor revisions + shortening; factor 2 algebra mistake correcte

    Quantum Monte Carlo calculations of neutron-alpha scattering

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    We describe a new method to treat low-energy scattering problems in few-nucleon systems, and we apply it to the five-body case of neutron-alpha scattering. The method allows precise calculations of low-lying resonances and their widths. We find that a good three-nucleon interaction is crucial to obtain an accurate description of neutron-alpha scattering.Comment: 4 pages, 2 figures, submitted to Physical Review Letter

    Relationship between antihypertensive medications and cognitive impairment: Part I. review of human studies and clinical trials

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    Purpose of review: There is an established association between hypertension and increased risk of poor cognitive performance and dementia including Alzheimer’s disease; however, associations between antihypertensive medications (AHMs) and dementia risk are less consistent. An increased interest in AHM has resulted in expanding publications; however, none of the recent reviews are comprehensive. Our extensive review includes 15 observational and randomized controlled trials (RCTs) published over the last 5 years, assessing the relationship between AHM and cognitive impairment. Recent findings: All classes of AHM showed similar result patterns in human studies with the majority of study results reporting point estimates below one and only a small number of studies (N = 15) reporting statistically significant results in favor of a specific class. Summary: Only a small number of studies reported statistically significant results in favor of a specific class of AHM. Methodological limitations of the studies prevent definitive conclusions. Further work is now needed to evaluate the class of AHM and cognitive outcomes in future RCTs, with a particular focus on the drugs with the promising results in both animals and human observational studies

    Approach to Perturbative Results in the N-Delta Transition

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    We show that constraints from perturbative QCD calculations play a role in the nucleon to Delta(1232) electromagnetic transition even at moderate momentum transfer scales. The pQCD constraints, tied to real photoproduction data and unseparated resonance response functions, lead to explicit forms for the helicity amplitudes wherein the E2/M1 ratio remains small at moderately large momentum transfer.Comment: 4 pages, 2 figures, ReVTe
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