229 research outputs found

    The Solar Proton Burning Process Revisited In Chiral Perturbation Theory

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    The proton burning process p + p -> d + e(+) + \nu(e), important for the stellar evolution of main-sequence stars of mass equal to or less than that of the Sun, is computed in effective field theory using chiral perturbation expansion to the next-to-next-to leading chiral order. This represents a model-independent calculation consistent with low-energy effective theory of QCD comparable in accuracy to the radiative np capture at thermal energy previously calculated by first using very accurate two-nucleon wavefunctions backed up by an effective field theory technique with a finite cut-off. The result obtained thereby is found to support within theoretical uncertainties the previous calculation of the same process by Bahcall and his co-workers.Comment: 30 pages, 2 eps files, aaspp4.sty needed, slightly modified, to be published in Ap.

    Radiative Neutron-Proton Capture in Effective Chiral Lagrangians

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    We calculate the cross-section for the thermal n+pd+γn+p\rightarrow d+\gamma process in chiral perturbation theory to next-to-next-to-leading order using heavy-fermion formalism. The exchange current correction is found to be (4.5±0.3) %(4.5\pm 0.3)~\% in amplitude and the chiral perturbation at one-loop order gives the cross section \sigma_{th}^{np}=(334\pm 2)\ {\mbox mb} which is in agreement with the experimental value (334.2\pm 0.5)\ {\mbox mb}. Together with the axial charge transitions, this provides a strong support for the power of chiral Lagrangians for nuclear physics.Comment: 9 pages, revtex, uses epsfig.sty, 2 uuencoded figure

    Effect of the National Resident Assessment Instrument on Selected Health Conditions and Problems

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/111253/1/j.1532-5415.1997.tb02972.x.pd

    A Case-Mix System for Adults with Developmental Disabilities

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    Effective management of publicly funded services matches the provision of needed services with cost-efficient payment methods. Payment systems that recognize differences in care needs (eg, case-mix systems) allow for greater proportions of available funds to be directed to providers supporting individuals with more needs. We describe a new way to allocate funds spent on adults with intellectual disabilities (ID) as part of a system-wide Medicaid payment reform initiative in Arkansas. Analyses were based on population-level data for persons living at home, collected using the interRAI ID assessment system, which were linked to paid service claims. We used automatic interactions detection to sort individuals into unique groups and provide a standardized relative measure of the cost of the services provided to each group. The final case-mix system has 33 distinct final groups and explains 26% of the variance in costs, which is similar to other systems in health and social services sectors. The results indicate that this system could be the foundation for a future case-mix approach to reimbursement and stand the test of “fairness” when examined by stakeholders, including parents, advocates, providers, and political entities

    Predictors of Aspiration Pneumonia in Nursing Home Residents

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    Aspiration pneumonia is a serious problem for the elderly institutionalized person, often requiring transfer to a hospital and a lengthy stay there. It is associated with a high mortality rate and is very costly to the health care system. The current study sought to determine the key predictors of aspiration pneumonia in a nursing home population with the hope that health care providers could identify those residents at highest risk and focus more efforts on prevention of this serious disease. A cross-sectional, retrospective analysis was done, using the Minimum Data Set (MDS) nursing home assessment data for three states (New York, Mississippi, Maine) from 1993 to 1994 ( N = 102,842). Nursing home residents were aged 65+. Standardized MDS summary scales and their component items were used, including: the Activities of Daily Living (ADL) scale, the cognitive performance scale (CPS), and the Resource Utilization Groups (RUGs). Results of these analyses showed the prevalence of pneumonia among this population was 3% ( n = 3118). Results from the logistic regression models indicated 18 significant predictors of aspiration pneumonia. The strongest to weakest predictors of pneumonia were, respectively, suctioning use, COPD, CHF, presence of feeding tube, bedfast, high case mix index, delirium, weight loss, swallowing problems, urinary tract infections, mechanically altered diet, dependence for eating, bed mobility, locomotion, number of medications, and age, while both CVA and tracheotomy care were inversely predictive of pneumonia. The emergence of these significant predictors suggested a different pathogenesis of pneumonia in the elderly nursing home resident from the acute care patient or the outpatient. Nursing home residents have chronic medical conditions that gradually lead to “decompensation” in functional status, nutritional status, and pulmonary clearance. Dysphagia and aspiration are common complications of their medical conditions and may slowly worsen as their status deteriorates. Alternatively, a sudden adverse event may dramatically increase the amount aspirated or the ability to resist infection and lead to sudden decompensation. Clinical staff must identify residents with dysphagia and aspiration and work to prevent decline in functional status in all residents. They must be aware of the dangers of adverse events that lead to sudden inactivity or illness and increase the risk of aspiration pneumonia. Prevention of this disease whenever possible will reduce costs, improve health outcomes, and improve our quality of care.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42428/1/20170298.pd

    Controlling Ferromagnetic Easy Axis in a Layered MoS2 Single Crystal

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    We report the effective methods to induce weak ferromagnetism in pristine MoS2 persisting up to room temperature with the improved transport property, which would lead to new spintronics devices. The hydrogenation of MoS2 by heating at 300 degrees C for 1 h leads to the easy axis out of plane, while the irradiation of proton with a dose of 1 x 10(13) P/cm(2) leads to the easy axis in plane. The theoretical modeling supports such magnetic easy axes.open16

    Effective Field Theory for Low-Energy Two-Nucleon Systems

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    We illustrate how effective field theories work in nuclear physics by using an effective Lagrangian in which all other degrees of freedom than the nucleonic one have been integrated out to calculate the low-energy properties of two-nucleon systems, viz, the deuteron properties, the np 1S0 scattering amplitude and the M1 transition amplitude entering into the radiative np capture process. Exploiting a finite cut-off regularization procedure, we find all the two-nucleon low-energy properties to be accurately described with little cut-off dependence, in consistency with the general philosophy of effective field theories.Comment: 4 pages, RevTeX, two eps files. Slightly modified. To appear in Rapid Communication Section of Phys. Rev.

    Controlling ferromagnetic easy axis in a layered MoS2 single crystal

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    We report the effective methods to induce weak ferromagnetism in pristine MoS2 persisting up to room temperature with the improved transport property, which would lead to new spintronics devices. The hydrogenation of MoS2 by heating at 300 degrees C for 1 h leads to the easy axis out of plane, while the irradiation of proton with a dose of 1 x 10(13) P/cm(2) leads to the easy axis in plane. The theoretical modeling supports such magnetic easy axes.open116160Nsciescopu

    Singular Cucker-Smale Dynamics

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    The existing state of the art for singular models of flocking is overviewed, starting from microscopic model of Cucker and Smale with singular communication weight, through its mesoscopic mean-filed limit, up to the corresponding macroscopic regime. For the microscopic Cucker-Smale (CS) model, the collision-avoidance phenomenon is discussed, also in the presence of bonding forces and the decentralized control. For the kinetic mean-field model, the existence of global-in-time measure-valued solutions, with a special emphasis on a weak atomic uniqueness of solutions is sketched. Ultimately, for the macroscopic singular model, the summary of the existence results for the Euler-type alignment system is provided, including existence of strong solutions on one-dimensional torus, and the extension of this result to higher dimensions upon restriction on the smallness of initial data. Additionally, the pressureless Navier-Stokes-type system corresponding to particular choice of alignment kernel is presented, and compared - analytically and numerically - to the porous medium equation

    The Rsr1/Bud1 GTPase Interacts with Itself and the Cdc42 GTPase during Bud-Site Selection and Polarity Establishment in Budding Yeast

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    Bimolecular fluorescence complementation assays allow the visualization of the homotypic and heterotypic GTPase interactions in vivo. The Rsr1 homotypic interaction involves its polybasic region and depends on its GDP-GTP exchange factor. Dimerization of GTPases may be an efficient mechanism to set up cellular asymmetry
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