26,201 research outputs found

    Weighted multivariate curve resolution – alternating least squares based on sample relevance

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    Alternating least squares, within the multivariate curve resolution framework has seen a lot of practical applications and shows its distinction with its relatively simple and flexible implementation. However, the limitations of least squares should be considered carefully when deviating from the standard assumed data structure. Within this work we highlight the effects of noise in the presence of minor components, and we propose a novel weighting scheme within the weighted multivariate curve-resolution-alternating least squares framework, to resolve it. Two simulated and one Raman imaging case is investigated, by comparing the novel methodology against standard multivariate curve resolution-alternating least squares and essential spectral pixel selection. A trade-off is observed between current methods, while the novel weighting scheme demonstrates a balance, where the benefits of the previous two methods are retained

    Pool boiling on modified surfaces using R-123

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    This article has been made available through the Brunel Open Access Publishing Fund.Saturated pool boiling of R-123 was investigated for five horizontal copper surfaces modified by different treatments, namely, an emery-polished surface, a fine sandblasted surface, a rough sandblasted surface, an electron beam-enhanced surface, and a sintered surface. Each 40-mm-diameter heating surface formed the upper face of an oxygen-free copper block, electrically heated by embedded cartridge heaters. The experiments were performed from the natural convection regime through nucleate boiling up to the critical heat flux, with both increasing and decreasing heat flux, at 1.01 bar, and additionally at 2 bar and 4 bar for the emery-polished surface. Significant enhancement of heat transfer with increasing surface modification was demonstrated, particularly for the electron beam-enhanced and sintered surfaces. The emery-polished and sandblasted surface results are compared with nucleate boiling correlations and other published data. © 2014 Syed W. Ahmad, John S. Lewis, Ryan J. McGlen, and Tassos G. Karayiannis Published with license by Taylor & Francis

    Thermalization through Hagedorn states - the importance of multiparticle collisions

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    Quick chemical equilibration times of hadrons within a hadron gas are explained dynamically using Hagedorn states, which drive particles into equilibrium close to the critical temperature. Within this scheme master equations are employed for the chemical equilibration of various hadronic particles like (strange) baryon and antibaryons. A comparison of the Hagedorn model to recent lattice results is made and it is found that for both Tc =176 MeV and Tc=196 MeV, the hadrons can reach chemical equilibrium almost immediately, well before the chemical freeze-out temperatures found in thermal fits for a hadron gas without Hagedorn states.Comment: 8 pages, 3 figures, talk presented at the International Conference on Strangeness in Quark Matter, Buzios, Rio de Janeiro, Brazil, Sept. 27 - Oct. 2, 200

    Pengaruh Waktu Inkubasi terhadap Biokonversi Reject Nanas Menjadi Bioetanol

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    Bioethanol can be produced through a fermentation process materials containing starch, sugar and cellulose fibers by fermentation by microorganisms. Bioethanol can be used as solvents, materials manufacture of perfumes, flavorings, food coloring, and drugs, and even can be used as an alternative fuel. Bioethanol production is done by a process bacth or also called bulk process. The purpose of this study was to determine the effect of incubation time and also get the optimum concentration of ethanol in the manufacture of bioethanol from pineapple reject. Stages of the manufacturing process starts from the substrate pineapple reject juice. Effect of incubation time will be done in this study with variations of 24, 48, 72, 96 and 120 hours. The number of cells during the incubation period will be analyzed by measuring the dry weight of the cell. Fermentation will take place over 4 days (96 hours) with a variation of 12, 24, 36, 48, 60, 72, 84 and 96 hours with the help of Saccharomyces cerevisiae. The results showed that the best time of incubation occurred at 24 and 48 hours with each cell weight of 9.8 g/L and 10.1 g/L at 96 hours of fermentation time and 48 hours which produces bioethanol concentration of 7%

    Neutrino oscillations from relativistic flavor currents

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    By resorting to recent results on the relativistic currents for mixed (flavor) fields, we calculate a space-time dependent neutrino oscillation formula in Quantum Field Theory. Our formulation provides an alternative to existing approaches for the derivation of space dependent oscillation formulas and it also accounts for the corrections due to the non-trivial nature of the flavor vacuum. By exploring different limits of our formula, we recover already known results. We study in detail the case of one-dimensional propagation with gaussian wavepackets both in the relativistic and in the non-relativistic regions: in the last case, numerical evaluations of our result show significant deviations from the standard formula.Comment: 16 pages, 4 figures, RevTe

    Lack of analgesic efficacy in female rats of\ud the commonly recommended oral dose of\ud buprenorphine

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    Previous work in our laboratory showed that the recommended oral dose of buprenorphine (0.5 mg/kg) was not as effective\ud as the standard therapeutic subcutaneous dose for postoperative analgesia in male Long-Evans (hooded) and Sprague-Dawley (albino) rats. The aim of the current study was to extend this analysis to female rats. We measured the pain threshold in adult female rats in diestrus or proestrus before and 30 and 60 min after oral buprenorphine (0.5 mg/kg,), the standard subcutaneous dose of buprenorphine (0.05 mg/kg), or vehicle only (1 ml/kg each orally and subcutaneously). Female rats showed an increased pain threshold (analgesia) after subcutaneous buprenorphine but no change in pain threshold after either oral buprenorphine or vehicle only. Estrous cycle stage (proestrus versus diestrus) did not affect the analgesic effects of buprenorphine, but rats in proestrus showed significantly lower pain thresholds (less tolerance to pain) than did those in diestrus. These results show that the oral dose of buprenorphine recommended for postoperative analgesic care does not induce significant analgesia in female rats and therefore is not as effective as the standard subcutaneous dose
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