1,626 research outputs found

    Fluorescence Spectroscopy of the Retina for Diagnosis of Transmissible Spongiform Encephalopathies

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    The feasibility of exploiting fluorescence spectra of the eye for diagnosis of transmissible spongiform encephalopathies (TSEs) was examined. Retinas from scrapie-positive sheep were compared with scrapie-negative sheep using fluorescence spectroscopy, and distinct differences in the fluorescence intensity and spectroscopic signatures were observed. The characteristic fluorescent signatures are thought to be the result of an accumulation of lipofuscin in the retina. It appears that the eye, in particular the retina, is a useful tissue for noninvasive examination of some neurological pathologies such as scrapie. The development of procedures based on examinations of the eye that permit the detection of neurological disorders in animals holds great promise

    Dynamic Solvation in Phosphonium Ionic Liquids:  Comparison of Bulk and Micellar Systems and Considerations for the Construction of the Solvation Correlation Function, C(t)

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    Dynamic solvation of the dye coumarin 153 is studied in a phosphonium ionic liquid:  hexadecyltributylphosphonium bromide, [(C4)3C16P+][Br-]. It forms micelles in water, and the bulk also exists as a liquid under our experimental conditions. This system permits a comparison with an imidazolium ionic liquid studied earlier, which also formed micelles in water (J. Phys. Chem. A 2006, 110, 10725−10730). We conclude that our analysis of the comparable situation in a phosphonium liquid is not as definitive as we had proposed earlier, i.e., that the majority of the early-time solvation arises from the organic cation. Part of the difficulty in performing this analysis is most likely due to the amount of water that is associated with the micelle. In the course of this work, we have focused on the calculation of the solvation correlation function, C(t), and investigated how it depends upon the methods with which the “zero-time” spectrum is constructed

    Influence of Chiral Ionic Liquids on the Excited-State Properties of Naproxen Analogs

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    The synthesis and decolorization of chiral room-temperature ionic liquids based upon 1-methyl imidazole and chloromethyl menthyl ether is reported. The excellent optical quality of these solvents permits the investigation of the effects of the two enantiomers on the excited-state photophysics of (S)-N-methyl-2-pyrrolidinemethyl 2(S)-(6-methoxy-2-naphthyl)propionate [(S,S)-NPX-PYR]. Whereas in conventional bulk polar solvents such as acetonitrile, (S,S)-NPX-PYR is known to execute excited-state intramolecular electron transfer and to form exciplexes, in these chiral solvents these nonradiative processes are absent. The chiral solvents do, however, induce a small but reproducible (∌10%) stereodifferentiation in the fluorescence lifetime of (S,S)-NPX-PYR as well as in the parent compound, (S)-naproxen. To our knowledge, this is the first example of chiral ionic liquids inducing such an effect on photophysical properties

    Optimasi Portofolio Resiko Menggunakan Model Markowitz MVO Dikaitkan dengan Keterbatasan Manusia dalam Memprediksi Masa Depan dalam Perspektif Al-Qur`an

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    Risk portfolio on modern finance has become increasingly technical, requiring the use of sophisticated mathematical tools in both research and practice. Since companies cannot insure themselves completely against risk, as human incompetence in predicting the future precisely that written in Al-Quran surah Luqman verse 34, they have to manage it to yield an optimal portfolio. The objective here is to minimize the variance among all portfolios, or alternatively, to maximize expected return among all portfolios that has at least a certain expected return. Furthermore, this study focuses on optimizing risk portfolio so called Markowitz MVO (Mean-Variance Optimization). Some theoretical frameworks for analysis are arithmetic mean, geometric mean, variance, covariance, linear programming, and quadratic programming. Moreover, finding a minimum variance portfolio produces a convex quadratic programming, that is minimizing the objective function ðð„with constraintsð ð ð„ „ ðandðŽð„ = ð. The outcome of this research is the solution of optimal risk portofolio in some investments that could be finished smoothly using MATLAB R2007b software together with its graphic analysis

    Search for heavy resonances decaying to two Higgs bosons in final states containing four b quarks

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    A search is presented for narrow heavy resonances X decaying into pairs of Higgs bosons (H) in proton-proton collisions collected by the CMS experiment at the LHC at root s = 8 TeV. The data correspond to an integrated luminosity of 19.7 fb(-1). The search considers HH resonances with masses between 1 and 3 TeV, having final states of two b quark pairs. Each Higgs boson is produced with large momentum, and the hadronization products of the pair of b quarks can usually be reconstructed as single large jets. The background from multijet and t (t) over bar events is significantly reduced by applying requirements related to the flavor of the jet, its mass, and its substructure. The signal would be identified as a peak on top of the dijet invariant mass spectrum of the remaining background events. No evidence is observed for such a signal. Upper limits obtained at 95 confidence level for the product of the production cross section and branching fraction sigma(gg -> X) B(X -> HH -> b (b) over barb (b) over bar) range from 10 to 1.5 fb for the mass of X from 1.15 to 2.0 TeV, significantly extending previous searches. For a warped extra dimension theory with amass scale Lambda(R) = 1 TeV, the data exclude radion scalar masses between 1.15 and 1.55 TeV

    MUSiC : a model-unspecific search for new physics in proton-proton collisions at root s=13TeV

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    Results of the Model Unspecific Search in CMS (MUSiC), using proton-proton collision data recorded at the LHC at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 35.9 fb(-1), are presented. The MUSiC analysis searches for anomalies that could be signatures of physics beyond the standard model. The analysis is based on the comparison of observed data with the standard model prediction, as determined from simulation, in several hundred final states and multiple kinematic distributions. Events containing at least one electron or muon are classified based on their final state topology, and an automated search algorithm surveys the observed data for deviations from the prediction. The sensitivity of the search is validated using multiple methods. No significant deviations from the predictions have been observed. For a wide range of final state topologies, agreement is found between the data and the standard model simulation. This analysis complements dedicated search analyses by significantly expanding the range of final states covered using a model independent approach with the largest data set to date to probe phase space regions beyond the reach of previous general searches.Peer reviewe

    Search for new particles in events with energetic jets and large missing transverse momentum in proton-proton collisions at root s=13 TeV

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    A search is presented for new particles produced at the LHC in proton-proton collisions at root s = 13 TeV, using events with energetic jets and large missing transverse momentum. The analysis is based on a data sample corresponding to an integrated luminosity of 101 fb(-1), collected in 2017-2018 with the CMS detector. Machine learning techniques are used to define separate categories for events with narrow jets from initial-state radiation and events with large-radius jets consistent with a hadronic decay of a W or Z boson. A statistical combination is made with an earlier search based on a data sample of 36 fb(-1), collected in 2016. No significant excess of events is observed with respect to the standard model background expectation determined from control samples in data. The results are interpreted in terms of limits on the branching fraction of an invisible decay of the Higgs boson, as well as constraints on simplified models of dark matter, on first-generation scalar leptoquarks decaying to quarks and neutrinos, and on models with large extra dimensions. Several of the new limits, specifically for spin-1 dark matter mediators, pseudoscalar mediators, colored mediators, and leptoquarks, are the most restrictive to date.Peer reviewe
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