2,023 research outputs found

    Shoikhet's Conjecture and Duflo Isomorphism on (Co)Invariants

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    In this paper we prove a conjecture of B. Shoikhet. This conjecture states that the tangent isomorphism on homology, between the Poisson homology associated to a Poisson structure on Rd and the Hochschild homology of its quantized star-product algebra, is an isomorphism of modules over the (isomorphic) respective cohomology algebras. As a consequence, we obtain a version of the Duflo isomorphism on coinvariants

    Quality of Imported Argentine Beef

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    A total of 8 lots of vacuum-packed bovine rump hearts (Gluteus medius muscle) imported in Italy from Argentina were submitted to microbiological (total bacterial count, Enterobacteriaceae, Pseudomonas spp., Lactobacilli, sulfite-reducing Clostridia, Listeria monocytogenes) and physicochemical analyses (pH, total volatile basic nitrogen, color measurement and shear force) after different storage times (35, 75 and 100 days). Lactobacilli were the predominant microbial population (about 6 log cfu/cm2), causing a microbial stabilization and acidification of meat. Seventy-three Lactobacilli isolates were submitted to random amplified polymorphic DNA-polymerase chain reaction and identified, showing a high prevalence of Lactobacillus sakei (in all the samples) and Lactobacillus curvatus (in samples stored for 75 or 100 days). We observed high total volatile basic nitrogen levels (>27 mgN/100 g) in all the samples and a discoloration of beef after the opening of the packs. Our results suggest the need for a higher standardization of production conditions. Practical Applications Vacuum-packed raw beef from Argentina is globally commercialized, and it is frequently shipped to European markets. Considering the perishability of this product and the very long shelf life assigned, the availability of microbiological and physicochemical data could be useful for quality evaluations purposes. Our data indicate that a long shelf life (3–4 months) is potentially achievable, but the application of the best hygienic practices during meat production and an optimal stabilization of microflora by the selection (or addition) of lactic acid bacteria must be assured. As protein degradation and microbial population showed to be stable during the shelf life, quality characteristics that are perceived by the consumer (such as color indexes) become important parameters for a proper evaluation of meat quality

    Characterization of the virulence, growth temperature and antibiotic resistance of the Campylobacter jejuni IAL 2383 strain isolated from humans

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    The objective of this study was to characterize the C. jejuni IAL2383 strain isolated from humans in Brazil. Transcripts for the racR, dnaJ and ciaB genes were found and flaA, plda and cadF genes were present in the genome and bacteria was sensitive to most of the important antimicrobials used to treat humans. C. jejuni IAL2383 is a good experimental model to analyze the interactions with cells

    Replacing sodium bicarbonate with half amount of calcareous marine algae in the diet of beef cattle

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    This study evaluated the effects of feeding calcareous marine algae or sodium bicarbonate as rumen buffer on the performance, behaviour, in vitro diet digestibility, and meat quality of beef cattle. A total of 180 Charolaise bullocks (536-38 kg; 14-1 months of age) were divided into two homogeneous groups and fed a diet with a mineral mix containing 40% sodium bicarbonate or 20% calcareous marine algae (CMA) for the entire fattening period (130 days). Of the in vivo and in vitro parameters evaluated, CMA supplementation improved average daily gain and feed conversion ratio and reduced the prevalence of bloat and lameness. Bullocks fed CMA tended to exhibit a calmer behaviour while in the pen. Supplementation with CMA improved rumen pH and in vitro digestion. Meat from bullocks fed CMA showed a lower pH and higher lightness and tenderness. The results suggest that CMA is more effective than sodium bicarbonate in buffering beef cattle, with a positive impact on growth performance, feed efficiency, health, and meat quality

    Intracranial pressure dynamics in patients with acute brain damage

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    The time pattern of intracranial pressure (ICP) during pressure-volume index (PVI) tests was analyzed in 20 patients with severe acute brain damage by means of a simple mathematical model. In most cases, a satisfactory fitting between model response and patient data was achieved by adjusting only four parameters: the cerebrospinal fluid (CSF) outflow resistance, the intracranial elastance coefficient, and the gain and time constant of cerebral autoregulation. The correlation between the parameter estimates was also analyzed to elucidate the main mechanisms responsible for ICP changes in each patient. Starting from information on the estimated parameter values and their correlation, the patients were classified into two main classes: those with weak autoregulation (8 of 20 patients) and those with strong autoregulation (12 of 20 patients). In the first group of patients, ICP mainly reflects CSF circulation and passive cerebral blood volume changes. In the second group, ICP exhibits paradoxical responses attributable to active changes in cerebral blood volume. Moreover, in two patients of the second group, the time constant of autoregulation is significantly increased (>40 s). The correlation between the parameter estimates was significantly different in the two groups of patients, suggesting the existence of different mechanisms responsible for ICP changes. Moreover, analysis of the correlation between the parameter estimates might give information on the directions of parameter changes that have a greater impact on ICP

    Baryon and Antibaryon Production in Hadronic and Nuclear Interactions

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    We introduce a new formulation of the diquark breaking mechanism which describes with no free parameters the huge nuclear stopping observed in central nucleus-nucleus collisions. Supplemented, in the dual parton model, with strings originating from diquark--antidiquark pairs from the nucleon sea, it gives a substantial increase of hyperon and antihyperon yields from pPbpPb to central PbPbPbPb collisions. Compared to data, this increase is slightly underestimated for Λ\Lambda's and Ξ\Xi's but is five times too small for Ω\Omega's. Introducing final state interactions, a reasonable description of all baryon and antibaryon yields is achieved.Comment: 17 pages, 4 postscript figure

    Deuteron Photodissociation in Ultraperipheral Relativistic Heavy-Ion on Deuteron Collisions

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    In ultraperipheral relativistic deuteron on heavy-ion collisions, a photon emitted from the heavy nucleus may dissociate the deuterium ion. We find deuterium breakup cross sections of 1.38 barns for deuterium-gold collisions at a center of mass energy of 200 GeV per nucleon, as studied at the Relativistic Heavy Ion Collider, and 2.49 barns for deuterium-lead collisions at a center of mass energy of 6.2 TeV, as proposed for the Large Hadron Collider. This cross section includes an energy-independent 140 mb contribution from hadronic diffractive dissociation. At the LHC, the cross section is as large as that of hadronic interactions. The estimated error is 5%. Deuteron dissociation could be used as a luminosity monitor and a `tag' for moderate impact parameter collisions.Comment: Final version, to appear in Phys. Rev. C. Diffractive dissociation included 10 pages with 3 figure

    HISTORICAL AND ARCHAEOSEISMIC STUDIES IN THE POLLINO AREA

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    Section 1. Reappraisal of the January 8, 1693 Pollino earthquake Section 2. Archaeoseismic field survey Section 3. Investigation of damaged speleothem

    Multi-GeV Electron Spectrometer

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    The advance in laser plasma acceleration techniques pushes the regime of the resulting accelerated particles to higher energies and intensities. In particular the upcoming experiments with the FLAME laser at LNF will enter the GeV regime with almost 1pC of electrons. From the current status of understanding of the acceleration mechanism, relatively large angular and energy spreads are expected. There is therefore the need to develop a device capable to measure the energy of electrons over three orders of magnitude (few MeV to few GeV) under still unknown angular divergences. Within the PlasmonX experiment at LNF a spectrometer is being constructed to perform these measurements. It is made of an electro-magnet and a screen made of scintillating fibers for the measurement of the trajectories of the particles. The large range of operation, the huge number of particles and the need to focus the divergence present unprecedented challenges in the design and construction of such a device. We will present the design considerations for this spectrometer and the first results from a prototype.Comment: 7 pages, 6 figures, submitted to NIM
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