485 research outputs found

    Lattice calculation of SU(3) flavor breaking ratios in B - anti-B mixing

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    We present an unquenched lattice calculation for the SU(3) flavor breaking ratios of the heavy-light decay constants and the ΔB=2\Delta B = 2 matrix elements. The calculation was performed on 163×3216^3 \times 32 lattices with two dynamical flavors of domain-wall quarks and inverse lattice spacing 1/a=1.69(5)1/a = 1.69(5) GeV. Heavy quarks were implemented using an improved lattice formulation of the static approximation. In the infinite heavy-quark mass limit we obtain fBs/fBd=1.29(4)(6)f_{B_s}/f_{B_d} = 1.29(4)(6), BBs/BBd=1.06(6)(4)B_{B_s}/B_{B_d} = 1.06(6)(4), ξ=1.33(8)(8)\xi = 1.33(8)(8) where the first error is statistical and the second systematic.Comment: 23 pages, 8 figures, RevTeX4; mentioned existence of 1/m_b corrections, minor changes improving readabilit

    Improved interpolating fields for hadrons at non-vanishing momentum

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    We demonstrate that a reduction in the noise-to-signal ratio may be obtained for hadrons at non-zero momenta whilst maintaining a good overlap with the ground state through a generalisation of Gaussian/Wuppertal smearing. The use of an anisotropic smearing wavefunction is motivated by the physical picture of a boosted hadron.Comment: 7 pages, 6 figures, poster presented at the 30th International Symposium on Lattice Field Theory (Lattice 2012), Cairns, Australia, June 24-29, 201

    The importance of vitamin D and omega-3 PUFA supplementation: a nonpharmacologic immunomodulation strategy to halt autoimmunity

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    The large, randomized, double-blind, placebo-controlled trial VITAL (Vitamin D and omega 3 trial) recently confirmed that vitamin D and omega-3 polyunsaturated fatty acid (PUFA) co-supplementation (VIDOM) can reduce the incidence of autoimmune diseases. Based on these relevant results, this commentary summarizes the molecular mechanisms behind the anti-inflammatory and immunomodulatory properties of vitamin D and omega-3 PUFAs. We also describe the potential bidirectional interplay between vitamin D metabolism and omega-3 PUFA metabolism that underlies the rationale for VIDOM co-supplementation and that may contribute to enhance the anti-inflammatory and immunomodulatory actions of vitamin D and omega-3 PUFAs when these compounds are administered in combination

    Non-perturbative renormalization of the static axial current in two-flavour QCD

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    We perform the non-perturbative renormalization of matrix elements of the static-light axial current by a computation of its scale dependence in lattice QCD with two flavours of massless O(a) improved Wilson quarks. The regularization independent factor that relates any running renormalized matrix element of the axial current in the static effective theory to the renormalization group invariant one is evaluated in the Schroedinger functional scheme, where in this case we find a significant deviation of the non-perturbative running from the perturbative prediction. An important technical ingredient to improve the precision of the results consists in the use of modified discretizations of the static quark action introduced earlier by our collaboration. As an illustration how to apply the renormalization of the static axial current presented here, we connect the bare matrix element of the current to the B_s-meson decay constant in the static approximation for one value of the lattice spacing, a ~ 0.08 fm, employing large-volume N_f=2 data at beta=5.3.Comment: 33 pages including figures and tables, latex2e, uses JHEP3.cls; version published in JHEP, small additions, results unchange

    The impact of vegan diet in the prevention and treatment of type 2 diabetes: A systematic review

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    A protective effect of vegan diets on health outcomes has been observed in previous studies, but its impact on diabetes is still debated. The aim of this review is to assess the relationship between vegan diets and the risk for type 2 diabetes (T2D) along with its effect on glycemic control and diabetes-related complications. In accordance with PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, Pubmed and Cochrane library databases were systematically searched for all relevant studies. Seven observational and eight randomized controlled (RCTs) studies were included. The methodological quality of studies was assessed using the National Institutes of Health quality assessment tool for observational cohort and cross-sectional studies and the Cochrane Risk of Bias Tool for RCTs. We found that a vegan diet is associated with lower T2D prevalence or incidence and in T2D patients decreases high glucose values and improves glucose homeostasis, as reported from the majority of included studies. This approach seems to be comparable to other recommended healthful eating models, but as it may have potential adverse effects associated with the long-term exclusion of some nutrients, appropriate nutritional planning and surveillance are recommended, particularly in specific groups of diabetic patients such as frail elderly, adolescents, and pregnant or breastfeeding women

    Improved interpolating fields for hadrons at non-zero momentum

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    We generalize Gaussian/Wuppertal smearing in order to produce non-spherical wave functions. We show that we can achieve a reduction in the noise-to-signal ratio for correlation functions of certain hadrons at non-zero momentum, while at the same time preserving a good projection on the ground state.Comment: 10 pages, 7 figures. Version accepted for publication in EPJ

    Nucleon electromagnetic form factors in two-flavour QCD

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    We present results for the nucleon electromagnetic form factors, including the momentum transfer dependence and derived quantities (charge radii and magnetic moment). The analysis is performed using O(a) improved Wilson fermions in Nf=2 QCD measured on the CLS ensembles. Particular focus is placed on a systematic evaluation of the influence of excited states in three-point correlation functions, which lead to a biased evaluation, if not accounted for correctly. We argue that the use of summed operator insertions and fit ans\"atze including excited states allow us to suppress and control this effect. We employ a novel method to perform joint chiral and continuum extrapolations, by fitting the form factors directly to the expressions of covariant baryonic chiral effective field theory. The final results for the charge radii and magnetic moment from our lattice calculations include, for the first time, a full error budget. We find that our estimates are compatible with experimental results within their overall uncertainties.Comment: 22 pages, 10 figures, citations modifie

    Dietary and protective factors to halt or mitigate progression of autoimmunity, covid-19 and its associated metabolic diseases

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    COVID-19 is without any doubt the worst pandemic we have faced since the H1N1 virus outbreak. Even if vaccination against SARS-CoV-2 infection is becoming increasingly available, a more feasible approach for COVID-19 prevention and therapy is still needed. Evidence of a pathological link between metabolic diseases and severe forms of COVID-19 has stimulated critical reflection and new considerations. In particular, an abnormal immune response observed in certain patients with SARS-CoV-2 infection suggested possible common predisposing risk factors with autoimmune diseases such as Type 1 Diabetes (T1D). Correct supplementation with dietary factors may be key to preventing and counteracting both the underlying metabolic impairment and the complications of COVID-19. A set of agents may inhibit the cytokine storm and hypercoagulability that characterize severe COVID-19 infection: vitamin D3, omega-3 polyunsaturated fatty acids, polyphenols like pterostilbene, polydatin and honokiol, which can activate anti-inflammatory and antioxidant sirtuins pathways, quercetin, vitamin C, zinc, melatonin, lactoferrin and glutathione. These agents could be highly beneficial for subjects who have altered immune responses. In this review, we discuss the antiviral and metabolic effects of these dietary factors and propose their combination for potential applications in the prevention and treatment of COVID-19. Rigorous studies will be fundamental for validating preventive and therapeutic protocols that could be of assistance to mitigate disease progression following SARS-CoV-2 infection
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