176 research outputs found

    Exact Gravitational Dual of a Plasma Ball

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    We present an exact solution for a black hole localized near an infrared wall in four-dimensional anti-deSitter space. By computing the holographic stress tensor we show that the CFT dual of the black hole is a 2+1-dimensional ball (i.e., a disk) of plasma at finite temperature, surrounded by vacuum. This confirms some earlier conjectures about plasma balls in AdS/CFT. We also estimate the value of the surface tension for the ball. The solution displays a number of peculiarities, most notably a non-trivial curvature of the boundary geometry, as well as other properties associated to the vanishing deconfinement temperature of the set up. We discuss how these features are related to specific physics at the infrared and ultraviolet boundaries for this solution, and should not be generic properties of plasma balls.Comment: 23 pages, 3 figure

    Type IIA/M-theory Moduli fixing in a Class of Orientifold Models

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    We present the study of type II A flux vacua and their M-theory duals for compactification on a class of Calabi-Yau orientifolds. The Kaehler potential is derived from toroidal compactifications and the superpotential contains a contribution from non-Abelian gauge degrees of freedoms. We obtain complete stabilisation of the moduli. We found one supersymmetric minimum and several non supersymmetric ones. Consistency of the analysis constrains the parameters of the models in a finite region containing a finite, although very large, number of flux vacua. From the M-theory side, we found some differences in the distributions of the physical quantities with respect to the M-theory ensemble studied by Acharya et al. In particular, it is easier to find small supersymmetry breaking scale.Comment: 37 pages, 4 figures, LaTeX. Extended one Section, added reference

    Correction of Italian under-reporting in the first COVID-19 wave via age-specific deconvolution of hospital admissions

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    When the COVID-19 pandemic first emerged in early 2020, healthcare and bureaucratic systems worldwide were caught off guard and largely unprepared to deal with the scale and severity of the outbreak. In Italy, this led to a severe underreporting of infections during the first wave of the spread. The lack of accurate data is critical as it hampers the retrospective assessment of nonpharmacological interventions, the comparison with the following waves, and the estimation and validation of epidemiological models. In particular, during the first wave, reported cases of new infections were strikingly low if compared with their effects in terms of deaths, hospitalizations and intensive care admissions. In this paper, we observe that the hospital admissions during the second wave were very well explained by the convolution of the reported daily infections with an exponential kernel. By formulating the estimation of the actual infections during the first wave as an inverse problem, its solution by a regularization approach is proposed and validated. In this way, it was possible to computed corrected time series of daily infections for each age class. The new estimates are consistent with the serological survey published in June 2020 by the National Institute of Statistics (ISTAT) and can be used to speculate on the total number of infections occurring in Italy during 2020, which appears to be about double the number officially recorded.Comment: 19 pages, 4 main figures, 2 supplementary figures, 2 table

    Bagger-Lambert Theory for General Lie Algebras

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    We construct the totally antisymmetric structure constants f^{ABCD} of a 3-algebra with a Lorentzian bi-invariant metric starting from an arbitrary semi-simple Lie algebra. The structure constants f^{ABCD} can be used to write down a maximally superconformal 3d theory that incorporates the expected degrees of freedom of multiple M2 branes, including the "center-of-mass" mode described by free scalar and fermion fields. The gauge field sector reduces to a three dimensional BF term, which underlies the gauge symmetry of the theory. We comment on the issue of unitarity of the quantum theory, which is problematic, despite the fact that the specific form of the interactions prevent the ghost fields from running in the internal lines of any Feynman diagram. Giving an expectation value to one of the scalar fields leads to the maximally supersymmetric 3d Yang-Mills Lagrangian with the addition of two U(1) multiplets, one of them ghost-like, which is decoupled at large g_YM.Comment: 12 pages, Latex; small corrections and references added; published version (small typos fixed

    Singularities and closed time-like curves in type IIB 1/2 BPS geometries

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    We study in detail the moduli space of solutions discovered in LLM relaxing the constraint that guarantees the absence of singularities. The solutions fall into three classes, non-singular, null-singular and time machines with a time-like naked singularity. We study the general features of these metrics and prove that there are actually just two generic classes of space-times - those with null singularities are in the same class as the non-singular metrics. AdS/CFT seems to provide a dual description only for the first of these two types of space-time in terms of a unitary CFT indicating the possible existence of a chronology protection mechanism for this class of geometries.Comment: 34 pages, 7 figures, LaTeX. References adde

    The GENIUS Grid Portal and robot certificates: a new tool for e-Science

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    <p>Abstract</p> <p>Background</p> <p>Grid technology is the computing model which allows users to share a wide <it>pletora </it>of distributed computational resources regardless of their geographical location. Up to now, the high security policy requested in order to access distributed computing resources has been a rather big limiting factor when trying to broaden the usage of Grids into a wide community of users. Grid security is indeed based on the Public Key Infrastructure (PKI) of X.509 certificates and the procedure to get and manage those certificates is unfortunately not straightforward. A first step to make Grids more appealing for new users has recently been achieved with the adoption of robot certificates.</p> <p>Methods</p> <p>Robot certificates have recently been introduced to perform automated tasks on Grids on behalf of users. They are extremely useful for instance to automate grid service monitoring, data processing production, distributed data collection systems. Basically these certificates can be used to identify a person responsible for an unattended service or process acting as client and/or server. Robot certificates can be installed on a smart card and used behind a portal by everyone interested in running the related applications in a Grid environment using a user-friendly graphic interface. In this work, the GENIUS Grid Portal, powered by EnginFrame, has been extended in order to support the new authentication based on the adoption of these robot certificates.</p> <p>Results</p> <p>The work carried out and reported in this manuscript is particularly relevant for all users who are not familiar with personal digital certificates and the technical aspects of the Grid Security Infrastructure (GSI). The valuable benefits introduced by robot certificates in e-Science can so be extended to users belonging to several scientific domains, providing an asset in raising Grid awareness to a wide number of potential users.</p> <p>Conclusion</p> <p>The adoption of Grid portals extended with robot certificates, can really contribute to creating transparent access to computational resources of Grid Infrastructures, enhancing the spread of this new paradigm in researchers' working life to address new global scientific challenges. The evaluated solution can of course be extended to other portals, applications and scientific communities.</p

    Impact of Preoperative Patient Characteristics and Flow Rate on Failure, Early Complications, and Voiding Dysfunction After a Transobturator Tape Procedure: A Multicentre Study

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    Purpose: To evaluate the impact of preoperative patient characteristics and flow rate on failure, early postoperative complications, and voiding in patients who underwent transvaginal tension-free vaginal tape-obturator (TVT-O) treatment for uncomplicated stress urinary incontinence (SUI).Methods: We retrospectively reviewed patients who underwent TVT-O for SUI at 3 Italian centres. The exclusion criteria were predominant voiding and storage symptoms suggestive of detrusor overactivity, the presence of grade > 1 urogenital prolapse, previous pelvic radiotherapy or other clinical contraindications for surgical procedures, neurogenic bladder dysfunction, and collagen diseases. Multivariate logistic regression models were constructed to identify predictors of early voiding dysfunction after TVT-O.Results: A total of 219 patients underwent TVT-O between January 2010 and December 2015. All patients received follow-up at 3, 6, and 12 months, and underwent a stress test, uroflowmetry, and bladder ultrasound to evaluate the postvoid residual volume. They also responded to the Urogenital Distress Inventory (UDI-6) questionnaire. The rates of persistent incontinence after TVT-O, postoperative complications, and satisfaction were 16.4% (36 of 219), 24.2% (53 of 219), and 86.3% (189 of 219), respectively. Nineteen patients (9.5%) experienced early voiding dysfunction. Based on an analysis of baseline characteristics, we determined that a cutoff value of 9.0 on the UDI-6 predicted postoperative SUI with 62% specificity, 72% sensitivity, and 66% accuracy. In the multivariate logistic regression analysis, a preoperative UDI-6 >= 9.0 was an independent predictor of postoperative SUI. The predictors of complications were menopause (P = 0.04) and the preoperative UDI-6 score (P = 0.01).Conclusions: Menopause and UDI-6 scores could be prognostic factors for persistent SUI after TVT-O. Well-designed prospective studies with a suitable number of patients are needed to corroborate our findings

    Management of pregnancy in autoimmune rheumatic diseases: maternal disease course, gestational and neonatal outcomes and use of medications in the prospectiveItalian P-RHEUM.it study

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    Objectives To investigate pregnancy outcomes in women with autoimmune rheumatic diseases (ARD) in the Italian prospective cohort study P-RHEUM.it. Methods Pregnant women with different ARD were enrolled for up to 20 gestational weeks in 29 Rheumatology Centres for 5 years (2018-2023). Maternal and infant information were collected in a web-based database. Results We analysed 866 pregnancies in 851 patients (systemic lupus erythematosus was the most represented disease, 19.6%). Maternal disease flares were observed in 135 (15.6%) pregnancies. 53 (6.1%) pregnancies were induced by assisted reproduction techniques, 61 (7%) ended in miscarriage and 11 (1.3%) underwent elective termination. Obstetrical complications occurred in 261 (30.1%) pregnancies, including 2.3% pre-eclampsia. Two cases of congenital heart block were observed out of 157 pregnancies (1.3%) with anti-Ro/SSA. Regarding treatments, 244 (28.2%) pregnancies were treated with glucocorticoids, 388 (44.8%) with hydroxychloroquine, 85 (9.8%) with conventional synthetic disease-modifying anti-rheumatic drugs and 122 (14.1%) with biological disease-modifying anti-rheumatic drugs. Live births were 794 (91.7%), mostly at term (84.9%); four perinatal deaths (0.5%) occurred. Among 790 newborns, 31 (3.9%) were small-for-gestational-age and 169 (21.4%) had perinatal complications. Exclusive maternal breast feeding was received by 404 (46.7%) neonates. The Edinburgh Postnatal Depression Scale was compiled by 414 women (52.4%); 89 (21.5%) scored positive for emotional distress. Conclusions Multiple factors including preconception counselling and treat-to-target with pregnancy-compatible medications may have contributed to mitigate disease-related risk factors, yielding limited disease flares, good pregnancy outcomes and frequency of complications which were similar to the Italian general obstetric population. Disease-specific issues need to be further addressed to plan preventative measures
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