257 research outputs found

    Chiral symmetry, Confinement and Nuclear Matter properties

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    We discuss the possible influence of fundamental QCD properties such as spontaneous chiral symmetry breaking and nucleon substructure on nuclear matter properties. We propose a chiral version of the relativistic σ−ω\sigma-\omega model in which the attractive background scalar field is associated with the chiral invariant field governing the radial fluctuations of the quark condensate. Nuclear matter stability is ensured once the scalar response of the nucleon depending on the quark confinement mechanism is properly incorporated. The needed parameters are estimated from lattice results and a satisfactory description of bulk properties follows, the only really free parameter being the ωNN\omega NN coupling constant. Pion loops can be also incorporated to obtain in a consistent way the finite density chiral susceptibilities. A good description of the asymmetry energy is obtained once the full rho meson exchange and Fock terms are included.Comment: Lecture given by G. Chanfray at the Theoretical Nuclear Physics School, 8-17 may 2007, Les Houches, Franc

    Relativistic Chiral Hartree-Fock description of nuclear matter with constraints from nucleon structure and confinement

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    We present a relativistic chiral effective theory for symmetric and asymmetric nuclear matter taken in the Hartree-Fock scheme. The nuclear binding is insured by a background chiral invariant scalar field associated with the radial fluctuations of the chiral quark condensate. Nuclear matter saturation is obtained once the scalar response of the nucleon generating three-body repulsive forces is incorporated. For these parameters related to the scalar sector and quark confinement mechanism inside the nucleon we make use of an analysis of lattice results on the nucleon mass evolution with the quark mass. The other parameters are constrained as most as possible by standard hadron and nuclear phenomenology. Special attention is paid to the treatment of the propagation of the scalar fluctuations. The rearrangement terms associated with in-medium modified mass and coupling constants are explicitly included to satisfy the Hugenholtz -Van Hove theorem. We point out the important role of the tensor piece of the rho exchange Fock term to reproduce the asymmetry energy of nuclear matter. We also discuss the isospin dependence of the Landau nucleon effective mass.Comment: Submitted to Physical Review

    Phase diagram of neutron-rich nuclear matter and its impact on astrophysics

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    Dense matter as it can be found in core-collapse supernovae and neutron stars is expected to exhibit different phase transitions which impact the matter composition and equation of state, with important consequences on the dynamics of core-collapse supernova explosion and on the structure of neutron stars. In this paper we will address the specific phenomenology of two of such transitions, namely the crust-core solid-liquid transition at sub-saturation density, and the possible strange transition at super-saturation density in the presence of hyperonic degrees of freedom. Concerning the neutron star crust-core phase transition at zero and finite temperature, it will be shown that, as a consequence of the presence of long-range Coulomb interactions, the equivalence of statistical ensembles is violated and a clusterized phase is expected which is not accessible in the grand-canonical ensemble. A specific quasi-particle model will be introduced to illustrate this anomalous thermodynamics and some quantitative results relevant for the supernova dynamics will be shown. The opening of hyperonic degrees of freedom at higher densities corresponding to the neutron stars core modifies the equation of state. The general characteristics and order of phase transitions in this regime will be analyzed in the framework of a self-consistent mean-field approach.Comment: Invited Talk given at the 11th International Conference on Nucleus-Nucleus Collisions (NN2012), San Antonio, Texas, USA, May 27-June 1, 2012. To appear in the NN2012 Proceedings in Journal of Physics: Conference Series (JPCS

    Weak and strong fillability of higher dimensional contact manifolds

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    For contact manifolds in dimension three, the notions of weak and strong symplectic fillability and tightness are all known to be inequivalent. We extend these facts to higher dimensions: in particular, we define a natural generalization of weak fillings and prove that it is indeed weaker (at least in dimension five),while also being obstructed by all known manifestations of "overtwistedness". We also find the first examples of contact manifolds in all dimensions that are not symplectically fillable but also cannot be called overtwisted in any reasonable sense. These depend on a higher-dimensional analogue of Giroux torsion, which we define via the existence in all dimensions of exact symplectic manifolds with disconnected contact boundary.Comment: 68 pages, 5 figures. v2: Some attributions clarified, and other minor edits. v3: exposition improved using referee's comments. Published by Invent. Mat

    Deposition of tin oxide, iridium and iridium oxide films by metal-organic chemical vapor deposition for electrochemical wastewater treatment

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    In this research, the specific electrodes were prepared by metal-organic chemical vapor deposition (MOCVD) in a hot-wall CVD reactor with the presence of O2 under reduced pressure. The Ir protective layer was deposited by using (Methylcyclopentadienyl) (1,5-cyclooctadiene) iridium (I), (MeCp)Ir(COD), as precursor. Tetraethyltin (TET) was used as precursor for the deposition of SnO2 active layer. The optimum condition for Ir film deposition was at 300 °C, 125 of O2/(MeCp)Ir(COD) molar ratio and 12 Torr of total pressure. While that of SnO2 active layer was at 380 °C, 1200 of O2/TET molar ratio and 15 Torr of total pressure. The prepared SnO2/Ir/Ti electrodes were tested for anodic oxidation of organic pollutant in a simple three-electrode electrochemical reactor using oxalic acid as model solution. The electrochemical experiments indicate that more than 80% of organic pollutant was removed after 2.1 Ah/L of charge has been applied. The kinetic investigation gives a two-step process for organic pollutant degradation, the kinetic was zero-order and first-order with respect to TOC of model solution for high and low TOC concentrations, respectively

    The Need to Develop Standard Measures of Patient Adherence for Big Data: Viewpoint

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    Despite half a century of dedicated studies, medication adherence remains far from perfect, with many patients not taking their medications as prescribed. The magnitude of this problem is rising, jeopardizing the effectiveness of evidence-based therapies. An important reason for this is the unprecedented demographic change at the beginning of the 21st century. Aging leads to multimorbidity and complex therapeutic regimens that create a fertile ground for nonadherence. As this scenario is a global problem, it needs a worldwide answer. Could this answer be provided, given the new opportunities created by the digitization of health care? Daily, health-related information is being collected in electronic health records, pharmacy dispensing databases, health insurance systems, and national health system records. These big data repositories offer a unique chance to study adherence both retrospectively and prospectively at the population level, as well as its related factors. In order to make full use of this opportunity, there is a need to develop standardized measures of adherence, which can be applied globally to big data and will inform scientific research, clinical practice, and public health. These standardized measures may also enable a better understanding of the relationship between adherence and clinical outcomes, and allow for fair benchmarking of the effectiveness and cost-effectiveness of adherence-targeting interventions. Unfortunately, despite this obvious need, such standards are still lacking. Therefore, the aim of this paper is to call for a consensus on global standards for measuring adherence with big data. More specifically, sound standards of formatting and analyzing big data are needed in order to assess, uniformly present, and compare patterns of medication adherence across studies. Wide use of these standards may improve adherence and make health care systems more effective and sustainable

    Persistence as a Robust Indicator of Medication Adherence-Related Quality and Performance.

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    Medication adherence is a priority for health systems worldwide and is widely recognised as a key component of quality of care for disease management. Adherence-related indicators were rarely explicitly included in national health policy agendas. One barrier is the lack of standardised adherence terminology and of routine measures of adherence in clinical practice. This paper discusses the possibility of developing adherence-related performance indicators highlighting the value of measuring persistence as a robust indicator of quality of care. To standardise adherence and persistence-related terminology allowing for benchmarking of adherence strategies, the European Ascertaining Barriers for Compliance (ABC) project proposed a Taxonomy of Adherence in 2012 consisting of three components: initiation, implementation, discontinuation. Persistence, which immediately precedes discontinuation, is a key element of taxonomy, which could capture adherence chronology allowing the examination of patterns of medication-taking behaviour. Advances in eHealth and Information Communication Technology (ICT) could play a major role in providing necessary structures to develop persistence indicators. We propose measuring persistence as an informative and pragmatic measure of medication-taking behaviour. Our view is to develop quality and performance indicators of persistence, which requires investing in ICT solutions enabling healthcare providers to review complete information on patients' medication-taking patterns, as well as clinical and health outcomes

    Characterisation of the Fusarium graminearum-Wheat Floral Interaction

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    Fusarium Ear Blight is a destructive fungal disease of cereals including wheat and can contaminate the crop with various trichothecene mycotoxins. This investigation has produced a new ÎČ-glucuronidase (GUS) reporter strain that facilitates the quick and easy assessment of plant infection. The constitutively expressed gpdA:GUS strain of Fusarium graminearum was used to quantify the overall colonisation pattern. Histochemical and biochemical approaches confirmed, in susceptible wheat ear infections, the presence of a substantial phase of symptomless fungal growth. Separate analyses demonstrated that there was a reduction in the quantity of physiologically active hyphae as the wheat ear infection proceeded. A simplified linear system of rachis infection was then utilised to evaluate the expression of several TRI genes by RT-qPCR. Fungal gene expression at the advancing front of symptomless infection was compared with the origin of infection in the rachis. This revealed that TRI gene expression was maximal at the advancing front and supports the hypothesis that the mycotoxin deoxynivalenol plays a role in inhibiting plant defences in advance of the invading intercellular hyphae. This study has also demonstrated that there are transcriptional differences between the various phases of fungal infection and that these differences are maintained as the infection proceeds

    Glycine-Stabilized Zinc Gluconate has similar bioavailability than Zinc Sulfate in a zinc fortified probiotic food

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    Objective: In this study, we evaluated zinc gluconate stabilized with glycine (GZ) and sulfate (SZ) in fermented milk as vehicle. Zinc bioavailability was evaluated in an animal model (Sprague Dawley rats) for both zinc sources in the vehicle with a probiotic (Lactobacillus casei DN114001). Results: For growth parameters, higher weight gain and femur weight values were observed when probiotic and zinc were provided together, independent of the source (weight gain: SZ 81.4g±4.0g; GZ 81.8g±4.0g and 70.2g±12.5g without the probiotic; femur weight: SZ 0.51g ±0.05g; GZ 0.52g±0.05g and 0.42g±0.03g without the probiotic). Femur zinc content was higher for zinc gluconate stabilized with glycine in the presence of the probiotic (97.04ppm±8.40ppm), and the results were similar for zinc sulfate with or without probiotic (84.51ppm±2.44ppm and 84.94ppm±2.28ppm, respectively). Serum antioxidant capacity and immune cellular response were also evaluated by using free radical scavenging assays and a T cell proliferation assay respectively. The free radical scavenging assay showed a tendency to increase with zinc provision, and the highest proliferation index was observed for glycine-stabilized zinc gluconate and the probiotic. Conclusion: The results indicate that the combination of zinc (as glycine-stabilized zinc gluconate) and a probiotic may be beneficial for the evaluated parameters.Fil: Tesan, Fiorella Carla. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Fisicomatemåtica. Cåtedra de Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Hernåndez, F.. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Fisicomatemåtica. Cåtedra de Física; ArgentinaFil: Torti, Horacio Emilio. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Fisicomatemåtica. Cåtedra de Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Massot, Francisco. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Fisicomatemåtica. Cåtedra de Física; ArgentinaFil: Huarte, M.. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Fisicomatemåtica. Cåtedra de Física; ArgentinaFil: Rubín de Celis, E.. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Fisicomatemåtica. Cåtedra de Física; ArgentinaFil: Barreiro Arcos, María Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Centro de Estudios Farmacológicos y Botånicos. Universidad de Buenos Aires. Facultad de Medicina. Centro de Estudios Farmacológicos y Botånicos; ArgentinaFil: Weill, R.. Danone Argentina S,a,; ArgentinaFil: Cremaschi, Graciela Alicia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Centro de Estudios Farmacológicos y Botånicos. Universidad de Buenos Aires. Facultad de Medicina. Centro de Estudios Farmacológicos y Botånicos; ArgentinaFil: Boccio, J.. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Fisicomatemåtica. Cåtedra de Física; ArgentinaFil: Salgueiro, María Jimena. Universidad de Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin
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