446 research outputs found

    Evaluation of a Phosphate Management Protocol to Achieve Optimum Serum Phosphate Levels in Hemodialysis Patients

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    Original article can be found at: http://www.sciencedirect.com/science/journal/10512276 Copyright National Kidney Foundation, Inc. DOI: 10.1053/j.jrn.2008.05.003To evaluate the effectiveness of a protocol designed to optimize serum phosphate levels in patients undergoing regular hemodialysis (HD).Peer reviewe

    Histological evaluation of microfilled and conventional composite resins on monkey dental pulps

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    The pulpal responses to two micro-filled composite resins and a conventional composite resin were investigated in adult rhesus monkey teeth. All materials were randomly placed in unetched and unlined class V buccal cavity preparations. A total of 90 teeth were used in the study. Each material was evaluated at 3 days, 5 weeks and 8 weeks. Following perfusion, the teeth were prepared using routine histological procedures. The results indicated that the pulpal response to the microfilled and conventional composite resins were similar for all time periods, characterized by an initial slight to moderate response at 3 days, followed at 5 and 8 weeks by a zero to slight response with evidence of reparative dentine formation. Brown and Brenn staining for bacteria indicated positive staining reactions along the cavity wails of all teeth for all materials at each time period.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73366/1/j.1365-2591.1985.tb00453.x.pd

    Heart of Darkness: The Significance of the Zeptobarn Scale for Neutralino Direct Detection

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    The direct detection of dark matter through its elastic scattering off nucleons is among the most promising methods for establishing the particle identity of dark matter. The current bound on the spin-independent scattering cross section is sigma^SI < 10 zb for dark matter masses m_chi ~ 100 GeV, with improved sensitivities expected soon. We examine the implications of this progress for neutralino dark matter. We work in a supersymmetric framework well-suited to dark matter studies that is simple and transparent, with models defined in terms of four weak-scale parameters. We first show that robust constraints on electric dipole moments motivate large sfermion masses mtilde > 1 TeV, effectively decoupling squarks and sleptons from neutralino dark matter phenomenology. In this case, we find characteristic cross sections in the narrow range 1 zb 70 GeV. As sfermion masses are lowered to near their experimental limit mtilde ~ 400 GeV, the upper and lower limits of this range are extended, but only by factors of around two, and the lower limit is not significantly altered by relaxing many particle physics assumptions, varying the strange quark content of the nucleon, including the effects of galactic small-scale structure, or assuming other components of dark matter. Experiments are therefore rapidly entering the heart of dark matter-favored supersymmetry parameter space. If no signal is seen, supersymmetric models must contain some level of fine-tuning, and we identify and analyze several possibilities. Barring large cancellations, however, in a large and generic class of models, if thermal relic neutralinos are a significant component of dark matter, experiments will discover them as they probe down to the zeptobarn scale.Comment: 35 pages, 11 figures; v2: references added, figures extended to 2 TeV neutralino masses, XENON100 results included, published versio

    Prediction of Mechanical Properties of Polymers With Various Force Fields

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    The effect of force field type on the predicted elastic properties of a polyimide is examined using a multiscale modeling technique. Molecular Dynamics simulations are used to predict the atomic structure and elastic properties of the polymer by subjecting a representative volume element of the material to bulk and shear finite deformations. The elastic properties of the polyimide are determined using three force fields: AMBER, OPLS-AA, and MM3. The predicted values of Young s modulus and shear modulus of the polyimide are compared with experimental values. The results indicate that the mechanical properties of the polyimide predicted with the OPLS-AA force field most closely matched those from experiment. The results also indicate that while the complexity of the force field does not have a significant effect on the accuracy of predicted properties, small differences in the force constants and the functional form of individual terms in the force fields determine the accuracy of the force field in predicting the elastic properties of the polyimide

    Magnetic fields in supernova remnants and pulsar-wind nebulae

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    We review the observations of supernova remnants (SNRs) and pulsar-wind nebulae (PWNe) that give information on the strength and orientation of magnetic fields. Radio polarimetry gives the degree of order of magnetic fields, and the orientation of the ordered component. Many young shell supernova remnants show evidence for synchrotron X-ray emission. The spatial analysis of this emission suggests that magnetic fields are amplified by one to two orders of magnitude in strong shocks. Detection of several remnants in TeV gamma rays implies a lower limit on the magnetic-field strength (or a measurement, if the emission process is inverse-Compton upscattering of cosmic microwave background photons). Upper limits to GeV emission similarly provide lower limits on magnetic-field strengths. In the historical shell remnants, lower limits on B range from 25 to 1000 microGauss. Two remnants show variability of synchrotron X-ray emission with a timescale of years. If this timescale is the electron-acceleration or radiative loss timescale, magnetic fields of order 1 mG are also implied. In pulsar-wind nebulae, equipartition arguments and dynamical modeling can be used to infer magnetic-field strengths anywhere from about 5 microGauss to 1 mG. Polarized fractions are considerably higher than in SNRs, ranging to 50 or 60% in some cases; magnetic-field geometries often suggest a toroidal structure around the pulsar, but this is not universal. Viewing-angle effects undoubtedly play a role. MHD models of radio emission in shell SNRs show that different orientations of upstream magnetic field, and different assumptions about electron acceleration, predict different radio morphology. In the remnant of SN 1006, such comparisons imply a magnetic-field orientation connecting the bright limbs, with a non-negligible gradient of its strength across the remnant.Comment: 20 pages, 24 figures; to be published in SpSciRev. Minor wording change in Abstrac

    Lorentz breaking Effective Field Theory and observational tests

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    Analogue models of gravity have provided an experimentally realizable test field for our ideas on quantum field theory in curved spacetimes but they have also inspired the investigation of possible departures from exact Lorentz invariance at microscopic scales. In this role they have joined, and sometime anticipated, several quantum gravity models characterized by Lorentz breaking phenomenology. A crucial difference between these speculations and other ones associated to quantum gravity scenarios, is the possibility to carry out observational and experimental tests which have nowadays led to a broad range of constraints on departures from Lorentz invariance. We shall review here the effective field theory approach to Lorentz breaking in the matter sector, present the constraints provided by the available observations and finally discuss the implications of the persisting uncertainty on the composition of the ultra high energy cosmic rays for the constraints on the higher order, analogue gravity inspired, Lorentz violations.Comment: 47 pages, 4 figures. Lecture Notes for the IX SIGRAV School on "Analogue Gravity", Como (Italy), May 2011. V.3. Typo corrected, references adde

    Toward Automatic Label-Free Whispering Gallery Modes Biodetection with a Quantum Dot-Coated Microsphere Population

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    We explore a new calibration-free approach to biodetection based on whispering gallery modes (WGMs) without a reference measure and relative shifts. Thus, the requirement to keep track of the sensor position is removed, and a freely moving population of fluorophore-doped polystyrene microspheres can now fulfill this role of sensing resonator. Breaking free from fixed surface-based biosensing promotes adhesion between the microsphere sensors and the analytes since both can now be thoroughly mixed. The 70-nm-wide spectrum of green fluorescent microbeads allows us to monitor over 20 WGMs simultaneously without needing evanescent light coupling into the microspheres, hence enabling remote sensing. Since the exact radius of each microsphere is unknown a priori, it requires algorithmic analyses to obtain a reliable result for the refractive index of a solution. We first test our approach with different solutions of alcohol in water obtaining 3 × 10−4 precision on the refractive index at lower concentrations. Then, the solutions of bacterial spores in water yield clear evidence of biodetection in the statistical analysis of WGMs from 50 microspheres. To extend the fluorescence spectral range of our WGM sensors, we present preliminary results on coating microspheres with CdSe/ZnS quantum dots

    Heavy quarkonium: progress, puzzles, and opportunities

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    A golden age for heavy quarkonium physics dawned a decade ago, initiated by the confluence of exciting advances in quantum chromodynamics (QCD) and an explosion of related experimental activity. The early years of this period were chronicled in the Quarkonium Working Group (QWG) CERN Yellow Report (YR) in 2004, which presented a comprehensive review of the status of the field at that time and provided specific recommendations for further progress. However, the broad spectrum of subsequent breakthroughs, surprises, and continuing puzzles could only be partially anticipated. Since the release of the YR, the BESII program concluded only to give birth to BESIII; the BB-factories and CLEO-c flourished; quarkonium production and polarization measurements at HERA and the Tevatron matured; and heavy-ion collisions at RHIC have opened a window on the deconfinement regime. All these experiments leave legacies of quality, precision, and unsolved mysteries for quarkonium physics, and therefore beg for continuing investigations. The plethora of newly-found quarkonium-like states unleashed a flood of theoretical investigations into new forms of matter such as quark-gluon hybrids, mesonic molecules, and tetraquarks. Measurements of the spectroscopy, decays, production, and in-medium behavior of c\bar{c}, b\bar{b}, and b\bar{c} bound states have been shown to validate some theoretical approaches to QCD and highlight lack of quantitative success for others. The intriguing details of quarkonium suppression in heavy-ion collisions that have emerged from RHIC have elevated the importance of separating hot- and cold-nuclear-matter effects in quark-gluon plasma studies. This review systematically addresses all these matters and concludes by prioritizing directions for ongoing and future efforts.Comment: 182 pages, 112 figures. Editors: N. Brambilla, S. Eidelman, B. K. Heltsley, R. Vogt. Section Coordinators: G. T. Bodwin, E. Eichten, A. D. Frawley, A. B. Meyer, R. E. Mitchell, V. Papadimitriou, P. Petreczky, A. A. Petrov, P. Robbe, A. Vair

    A systematic review of how emotional self-awareness is defined and measured when comparing autistic and non-autistic groups

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    We would like to sincerely thank all the authors who shared their data with us. We would also like to thank Ira Lesser, Taylor Graeme, and Arvid Heiberg for kindly sharing their articles for the historical review. Review was conduced as part of CFH's PhD studies. We would like to thank the Northwood Trust, UK for their financial support for this research. Research data available upon request from first author.Peer reviewedPublisher PD
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