6,247 research outputs found

    The strange-quark chemical potential as an experimentally accessible "order parameter" of the deconfinement phase transition for finite baryon-density

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    We consider the change of the strange-quark chemical potential in the phase diagram of nuclear matter, employing the Wilson loop and scalar quark condensate order parameters, mass-scaled partition functions and enforcing flavor conservation. Assuming the region beyond the hadronic phase to be described by massive, correlated and interacting quarks, in the spirit of lattice and effective QCD calculations, we find the strange-quark chemical potential to change sign: from positive in the hadronic phase - to zero upon deconfinement - to negative in the partonic domain. We propose this change in the sign of the strange-quark chemical potential to be an experimentally accessible order parameter and a unique, concise and well-defined indication of the quark-deconfinement phase transition in nuclear matter.Comment: 22 pages, 14 figures within text, 2 figures(6,B3) as separate files. To be published in J.Phys.G: Nucl.&Part.Phys. G28 (2002

    Model of Centauro and strangelet production in heavy ion collisions

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    We discuss the phenomenological model of Centauro event production in relativistic nucleus-nucleus collisions. This model makes quantitative predictions for kinematic observables, baryon number and mass of the Centauro fireball and its decay products. Centauros decay mainly to nucleons, strange hyperons and possibly strangelets. Simulations of Centauro events for the CASTOR detector in Pb-Pb collisions at LHC energies are performed. The signatures of these events are discussed in detail.Comment: 19 pages, LaTeX+revtex4, 14 eps-figures and 3 table

    Wastewater valorization by pure bacterial cultures to Extracellular Polymeric Substances (EPS) with high emulsifying potential and flocculation activities

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    Nowadays much effort has been devoted for the development of cost-effective and environmentally friendly processes to obtain extracellular polymeric substances (EPS) with high emulsifying and flocculation activities. The aim of this study was to evaluate the capacity of bacterial strains previously isolated from oil-contaminated areas to produce EPS with high emulsification and bioflocculant properties during cultivation in domestic and bilge wastewater and in industrial crude glycerol. A total of seven bacterial strains were screened for EPS production, from which two strains, Pseudomonas aeruginosa LVD-10 and Enterobacter sp. SW, were selected as potential EPS producers. EPS with high emulsifying capacity in olive oil (a maximum of 96.6 and 89.8% for strain SW and LVD-10, respectively) was produced using bilge wastewater as substrate. EPS with a slightly lower emulsifying capacity was obtained using crude glycerol. In addition, the flocculation activity of the EPS extracted from strains LVD-10 and SW grown on crude glycerol was considerably higher (81.6 and 73.3%, respectively) than that obtained with other substrates. This is the first study that points out that EPS with emulsifying and flocculation potential activity can be produced from bilge wastewater and crude glycerol. The production of biopolymers with broad biotechnological applications using low-cost substrates can be a means to valorise waste streams.info:eu-repo/semantics/publishedVersio

    Revisiting UV/optical continuum time lags in AGN

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    In this paper, we present an updated version of our model (KYNXiltr) which considers thermal reverberation of a standard Novikov-Thorne accretion disc illuminated by an X-ray point-like source. Previously, the model considered only two cases of black hole spins, and assumed a colour correction factor fcol=2.4f_{\rm col} = 2.4. Now, we extend the model to any spin value and colour correction. In addition, we consider two scenarios of powering the X-ray corona, either via accretion, or external to the accretion disc. We use KYNXiltr to fit the observed time lags obtained from intense monitoring of four local Seyfert galaxies (NGC 5548, NGC 4395, Mrk 817, and Fairall 9). We consider various combinations of black hole spin, colour correction, corona height, and fraction of accretion power transferred to the corona. The model fits well the overall time-lags spectrum in these sources (for a large parameter space). For NGC 4593 only, we detect a significant excess of delays in the U-band. The contribution of the diffuse BLR emission in the time-lags spectrum of this source is significant. It is possible to reduce the large best-fitting parameter space by combining the results with additional information, such as the observed Eddington ratio and average X-ray luminosity. We also provide an update to the analytic expression provided by Kammoun et al., for an X-ray source that is not powered by the accretion process, which can be used for any value of colour correction, and for two values of the black hole spin (0 and 0.998).Comment: Accepted for publication in MNRA

    Performance Studies of Prototype II for the CASTOR forward Calorimeter at the CMS Experiment

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    We present results of the performance of the second prototype of the CASTOR quartz-tungsten sampling calorimeter, to be installed in the very forward region of the CMS experiment at the LHC. The energy linearity and resolution, as well as the spatial resolution of the prototype to electromagnetic and hadronic showers are studied with E=20-200 GeV electrons, E=20-350 GeV pions, and E=50,150 GeV muons from beam tests carried out at CERN/SPS in 2004. The responses of the calorimeter using two different types of photodetectors (avalanche photodiodes APDs, and photomultiplier tubes PMTs) are compared.Comment: 16 pages, 22 figs., submitted to EPJ-

    The Rourke Baby Record Infant/Child Maintenance Guide: do doctors use it, do they find it useful, and does using it improve their well-baby visit records?

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    Background. The Rourke Baby Record (RBR) - http://www.rourkebabyrecord.ca - is a freely available evidence-based structured form for child health surveillance from zero to five years. Family physicians/general practitioners (FP/GPs) doing office based well-baby care in three Ontario Canada cities (London, Ottawa, and Toronto) were randomly sampled to study the prevalence and utility of the RBR and documentation of well-baby visits. Methods. Database with telephone confirmation was conducted to assess the prevalence of use of the RBR. Study Part 1: Questionnaire mailed to a random sample of 100 RBR users. Outcome measures were utility of, helpfulness of, and suggestions for the RBR. Descriptive analysis was employed. Study Part 2: Retrospective chart review of well-baby visits by 38 FP/GPs using student t-tests and factor analysis. Outcome measures were well-baby visit documentation of growth, nutrition, safety issues, developmental milestones, physical examination, and overall comprehensiveness. Results. The RBR was used by 78.5% (402/512) of successfully contacted FP/GPs who did well-baby care in these 3 cities. Study Part 1: Questionnaire respondents (N = 41/100) used the RBR in several ways, and found it most helpful for assessing healthy child development, charting/recording the visits, managing time effectively, addressing parent concerns, identifying health problems, and identifying high risk situations. The RBR was seen to be least helpful as a tool for managing or for referring identified health problems. Study Part 2: Charts from a total of 1,378 well-baby visits on 176 children were audited. Well-baby care provided by the 20 FP/GPs who used the RBR compared to that by the 18 non-users was statistically more likely to include documentation of type of feeding (p = 0.023), discussion of safety issues (p < 0.001), assessment of development (p = 0.001), and overall comprehensiveness (p < 0.001). Well-baby care provided by the RBR users compared to that by the non-users was not more likely to include documentation of measurement of growth (p = 0.097), or physical examination (p = 0.828). Conclusion. The RBR was widely used by FP/GPs in these settings. RBR users found it helpful for many purposes, and had a consistently high rate of documentation of many aspects of well-baby care. The Rourke Baby Record has become a de facto gold standard clinical practice tool in knowledge translation for pediatric preventive medicine and health surveillance for primary care pediatric providers

    CASTOR: Centauro and Strange Object Research in nucleus-nucleus collisions at LHC

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    We describe the CASTOR detector designed to probe the very forward, baryon-rich rapidity region in nucleus-nucleus collisions at the LHC. We present a phenomenological model describing the formation of a QGP fireball in a high baryochemical potential environment, and its subsequent decay into baryons and strangelets. The model explains Centauros and the long-penetrating component and makes predictions for the LHC. Simulations of Centauro-type events were done. To study the response of the apparatus to new effects different exotic species (DCC, Centauros, strangelets etc.) were passed through the deep calorimeter. The energy deposition pattern in the calorimeter appears to be a new clear signature of the QGP.Comment: Talk given by E. Gladysz-Dziadus for the CASTOR group, Intern. Workshop on Nuclear Theory, 10-15 June, 2002, Bulgaria, Rila Mountains, 15 pages, 14 figure

    Formation of Centauro and Strangelets in Nucleus-Nucleus Collisions at the LHC and their Identification by the ALICE Experiment

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    We present a phenomenological model which describes the formation of a Centauro fireball in nucleus-nucleus interactions in the upper atmosphere and at the LHC, and its decay to non-strange baryons and Strangelets. We describe the CASTOR detector for the ALICE experiment at the LHC. CASTOR will probe, in an event-by-event mode, the very forward, baryon-rich phase space 5.6 < \eta < 7.2 in 5.5 A TeV central Pb + Pb collisions. We present results of simulations for the response of the CASTOR calorimeter, and in particular to the traversal of Strangelets.Comment: 4 pages, 4 figures, to appear in the proceedings of the 26th ICR

    Light particle spectra from 35 MeV/nucleon 12C-induced reactions on 197Au

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    Energy spectra for p, d, t, 3He, 4He, and 6He from the reaction 12C+197Au at 35 MeV/nucleon are presented. A common intermediate rapidity source is identified using a moving source fit to the spectra that yields cross sections which are compared to analogous data at other bombarding energies and to several different models. The excitation function of the composite to proton ratios is compared with quantum statistical, hydrodynamic, and thermal models
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