98 research outputs found

    Is the diagonal case a general picture for Loop Quantum Cosmology?

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    The correct implementation of the Loop Quantum Gravity to the early homogeneous Universe has been the subject of a long debate in the literature because the SU(2) symmetry cannot be properly retained. The role of this symmetry is expressed by the Gauss constraint. Here, a non-vanishing Gauss constraint is found. However, we show that using suitable variables, it can be recast into three Abelian constraints, justifying the absence of such a symmetry in Loop Quantum Cosmology.Comment: 6 page

    Influence of rotation on axisymmetric plasma equilibria: double-null DTT scenario

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    We study the dependence of some relevant tokamak equilibrium quantities on the toroidal plasma rotation. The Grad-Shafranov equation generalised to the rotating case is analytically solved employing two different representations for the homogenous solution. Using an expression in terms of polynomials, we describe the separatrix shape by a few geometrical parameters, reproducing different plasma scenarios such as double-null and inverse triangularity. In this setting, the introduction of toroidal rotation corresponds to variations on relevant plasma quantities, most notably an enhancement of the poloidal beta. Using a more general expression in terms of Bessel functions, we reconstruct the full plasma boundary of the double-null configuration proposed for the upcoming DTT experiment, demonstrating how said configuration is compatible with different values of the plasma velocity.Comment: 7 pages, 6 figures. Submitted to PPC

    Mixed diffusive-convective relaxation of a broad beam of energetic particles in cold plasma

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    We revisit the applications of quasi-linear theory as a paradigmatic model for weak plasma turbulence and the associated bump-on-tail problem. The work, presented here, is built around the idea that large-amplitude or strongly shaped beams do not relax through diffusion only and that there exists an intermediate time scale where the relaxations are convective (ballistic-like). We cast this novel idea in the rigorous form of a self-consistent nonlinear dynamical model, which generalizes the classic equations of the quasi-linear theory to "broad" beams with internal structure. We also present numerical simulation results of the relaxation of a broad beam of energetic particles in cold plasma. These generally demonstrate the mixed diffusive-convective features of supra-thermal particle transport; and essentially depend on nonlinear wave-particle interactions and phase-space structures. Taking into account modes of the stable linear spectrum is crucial for the self-consistent evolution of the distribution function and the fluctuation intensity spectrum.Comment: 25 pages, 15 figure

    Evolutionary Grad-Shafranov Equation for a Toroidal Plasma

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    We describe the evolution of a plasma equilibrium having a toroidal topology in the presence of constant electric resistivity. After outlining the main analytical properties of the solution, we reproduce the essential features of a scenario for the upcoming Italian experiment Divertor Tokamak Test Facility, with a good degree of accuracy. Although the theoretical lifetime is of the order of 104 10^4\,s, we observe a macroscopic change in plasma volume on a timescale comparable to the predicted duration of the plasma discharge. In the final part of the work, we compare our self-consistent solution to the more common Solov'ev one, and to a family of nonlinear configurations.Comment: 8 pages, 2 figure

    Autoimmune hepatitis triggered by SARS-CoV-2 vaccination.

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    The development of autoimmune diseases has been reported after SARS-CoV-2 infection. Vaccination against SARS-CoV-2 could also trigger auto-immunity, as it has been described with other vaccines. An aberrant immune response induced by molecular mimicry and bystander activation, especially in predisposed individuals, is a potential mechanism. We report the case of a 76-year-old woman with Hashimoto thyroiditis and prior COVID-19 infection who developed severe autoimmune hepatitis (with typical features including strongly positive anti-smooth muscle antibody and markedly elevated immunoglobulins G, as well as typical histological findings) following SARS-CoV-2 vaccination (mRNA-1273 SARS-CoV-2 vaccine, Moderna®). The link between SARS-CoV-2 vaccination and the development of autoimmune diseases needs to be further investigated. Although a causality relationship cannot be proven, caution may be warranted when vaccinating individuals with known autoimmune diseases

    Extensive chronic xanthogranulomatous intra-abdominal inflammation due to Mycoplasma hominis mimicking a malignancy: a case report

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    Introduction: While infectious peritonitis is a common occurrence in patients with liver cirrhosis, Mycoplasma is rarely identified as a causative agent. Case presentation: We report the case of a 43-year-old Caucasian woman presenting with an extensive abdominal conglomerate tumor mimicking malignancy. A histologic specimen showed a xanthogranulomatous inflammation. Subsequently, Mycoplasma hominis was identified as the specific causative infectious agent using a broad-range (eubacterial) polymerase chain reaction. To the best of our knowledge, this is the first reported case of an intra-abdominal Mycoplasma infection presenting as a conglomerate tumor. Conclusion: An unusual presentation of an inflammatory process in the abdomen or an insufficient response to conventional therapy should prompt clinicians to consider atypical infectious agents in the differential diagnosis. This case illustrates the potential of newer diagnostic methods, since certain fastidious microorganisms may not be diagnosed and treated appropriately using conventional means

    Linear analysis of the gravitational beam-plasma instability

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    We investigate the well-known phenomenon of the beam-plasma instability in the gravitational sector, when a fast population of particles interacts with the massive scalar mode of an Horndeski theory of gravity, resulting into the linear growth of the latter amplitude. Following the approach used in the standard electromagnetic case, we start from the dielectric representation of the gravita- tional plasma, as introduced in a previous analysis of the Landau damping for the scalar Horndeski mode. Then, we set up the modified Vlasov-Einstein equation, using at first a Dirac delta func- tion to describe the fast beam distribution. This way, we provide an analytical expression for the dispersion relation and we demonstrate the existence of non-zero growth rate for the linear evolu- tion of the Horndeski scalar mode. A numerical investigation is then performed with a trapezoidal beam distribution function, which confirms the analytical results and allows to demonstrate how the growth rate decreases as the beam spread increases

    Molecular and Histological Profiling Reveals an Innate-Shaped Immune Microenvironment in Solitary Juvenile Polyps.

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    INTRODUCTION Solitary juvenile polyps (JP) are characterized by a benign disease course with low recurrence rate but present with signs of intestinal inflammation. To better understand the underlying pathogenesis, we performed histological and molecular evaluation targeting distinct immune mechanisms. METHODS Pediatric patients with JP (n = 12), with treatment-naïve inflammatory bowel disease (IBD; [n = 41]) as inflammatory control, and non-IBD controls (n = 14) were investigated. For a comparative analysis of infiltrating immune cells, a next-generation tissue microarray of biopsies was assembled, immunostained, and scored. Targeted transcriptional profiling was performed using a customized immunology panel. RESULTS In JP, a predominant accumulation of neutrophils and eosinophils was observed. RNA expression profiles revealed increased levels of CXCL8, CXCL5, and CCL11 transcripts in JP, indicating an enhanced recruitment of neutrophils and eosinophils. Moreover, messenger RNA levels of the proinflammatory cytokine IL1b and the inflammation-amplifying receptor TREM1 were higher in JP, whereas we could not find signs of a functionally polarized Tcell response in JP when compared with IBD. DISCUSSION Patients with JP and patients with treatment-naïve IBD have distinct cell infiltrates during active disease. The ample presence of eosinophils in JP supports neutrophil accumulation, which is responsible for the elevated release of calprotectin. Intriguingly, however, we were not able to identify a functionally polarized T-cell response in JP, which indicates that during the acute onset of inflammation in JP, a potent adaptive immune memory is not established. This may explain the low reoccurrence rate of JP
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