85 research outputs found

    Dirac-Born-Infeld actions and Tachyon Monopoles

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    We investigate magnetic monopole solutions of the non-abelian DBI action describing 2 coincident non-BPS D9-branes in flat space. Just as in the case of kink and vortex solitonic tachyon solutions of the full DBI non-BPS actions, as previously analyzed by Sen, these monopole configurations are singular in the first instance and require regularization. We discuss a suitable non-abelian ansatz and show it solves the equations of motion to leading order in the regularization parameter. Fluctuations are studied and shown to describe a codimension 3 BPS D6-brane. A formula is derived for its tension. We comment on the implication to our results from both the trace (Tr) and symmetrized trace (Str) prescriptions of the non-abelian DBI action of coincident non-BPS D9-branes.Comment: 17 pages, jhep3.cl

    Phase Transitions in Separated Dp1D_{p-1} and anti-Dp1D_{p-1} Branes at Finite Temperature

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    We consider a pair of parallel Dp1{\rm D}_{p-1} and anti-Dp1{\rm D}_{p-1} branes in flat space, with a finite separation dd along some perpendicular spatial direction and at finite temperature. If this spatial direction is compactified on a circle then by T-duality, the system is equivalent to a Dp{\rm D}_{p}-anti Dp{\rm D}_{p} pair wrapped around the dual circle with a constant Wilson line AdA \approx d on one of the branes. We focus in particular on the p=9p=9 case and compute the free energy of this system and study the occurrence of second order phase transitions as both the temperature and Wilson line (brane-antibrane separation) are varied. In the limit of vanishing Wilson line we recover the previous results obtained in the literature, whereby the open string vacuum at the origin of the tachyon field T=0 is stabilized at sufficiently high temperature at which a second order phase transition occurs. For sufficiently large Wilson line, we find new second order phase transitions corresponding to the existence of two minima in the tachyon effective potential at finite temperature and tachyon field value. Entropic arguments suggest that as the system cools, the tachyon is likely to find itself in the minimum that approaches infinity as the temperature vanishes (i.e. the one corresponding to the closed string vacuum), rather than the minimum at T=0 (corresponding to the open string vacuum).Comment: 25 pages, 4 figures; Clarifications added to Section 3 concerning winding modes; updated plots of the effective potential in section 4; typos corrected. Version to be published in JHE

    GTEM Cell Experimental Set up for In Vitro Dosimetry

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    A GTEM cell, suitable for assessing possible biological effects induced on cell samples by electromagnetic fields at the typical frequencies of GSM mobile phones, has been designed and set up. Basic environmental requirements for in-vitro biological experiments, involving a GTEM cell, have been assessed by controlling the electromagnetic field distribution and survival conditions. The GTEM cell has been characterized by Standing Wave Ratio (SWR) and Time Domain Reflectometry (TDR) measurements. The impedance matching at the terminal load section has been optimized by considering different hybridload configurations. Moreover, optimal exposure conditions forthe biological sample have been experimentally evaluated by paying special attention to the E-field scenario inside the GTEM cell at 900 MHz and 1800 MHz frequencies. At last, an experimental evaluation of the Specific Absorption Rate (SAR) is reported

    Cardiovascular disease risk in liver transplant recipients transplanted due to chronic viral hepatitis

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    Background: Cardiovascular disease (CVD) is a major cause of morbidity and mortality after liver transplantation, mostly in patients transplanted for nonalcoholic steatohepatitis, obesity and diabetes. Few data exist on cardiovascular diseases among patients transplanted for viral hepatitis. Objective: Our aim is to clarify the cardiovascular risk and subclinical vascular damage among liver transplant recipients for chronic viral hepatitis (i.e. hepatits C virus, hepatis B virus and hepatitis D virus infection). Methods: Adult patients (age ≥ 18 years) with orthotopic liver transplants (OLT) due to viral hepatitis who signed informed consent, and were admitted for a routine follow-up between June 2019 and September 2020 at the Infectious Disease outpatient clinic of the University of Campania Luigi Vanvitelli, Naples, Italy, were prospectively enrolled. An estimation of cardiovascular risk was assessed using three main risk charts, echocolor-Doppler of epiaortic vessels was performed to assess subclinical Intima-Media changes. Results: A total of 161 patients were evaluated; of these 15 were excluded because not affected by viral hepatitis. 146 patients were considered. 83 patients (56.8%) were considered at high cardiovascular risk according to Framingham, 54 patients (36.9%) to American Heart Association Arteriosclerotic Cardiovascular Disease (ASCVD) score and 19 (13.0%) to Heart Score. Only 8 patients (5.4%) showed a normal carotid ultrasound, while 52 patients (35.6%) had a carotid artery Intima-Media Thickness (IMT) and 86 (58.9%) an atherosclerotic plaque. Conclusions: Liver transplant recipients for virus-related associated liver disease are, in light of the high percentage of carotid lesions, at high risk of CVD. Risk charts compared to subclinical carotid lesions which represent damage already established and a real localization of the disease, seem to underestimate the cardiovascular risk. A chronic inflammatory status, could play a key role. It's important to raise the awareness of cardiovascular risk in liver transplant patients to prevent cardiovascular diseases and improve the timing of early diagnosis of premature vascular lesions

    A genome wide association study for backfat thickness in Italian Large White pigs highlights new regions affecting fat deposition including neuronal genes.

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    open9noBACKGROUND: Carcass fatness is an important trait in most pig breeding programs. Following market requests, breeding plans for fresh pork consumption are usually designed to reduce carcass fat content and increase lean meat deposition. However, the Italian pig industry is mainly devoted to the production of Protected Designation of Origin dry cured hams: pigs are slaughtered at around 160 kg of live weight and the breeding goal aims at maintaining fat coverage, measured as backfat thickness to avoid excessive desiccation of the hams. This objective has shaped the genetic pool of Italian heavy pig breeds for a few decades. In this study we applied a selective genotyping approach within a population of ~ 12,000 performance tested Italian Large White pigs. Within this population, we selectively genotyped 304 pigs with extreme and divergent backfat thickness estimated breeding value by the Illumina PorcineSNP60 BeadChip and performed a genome wide association study to identify loci associated to this trait. RESULTS: We identified 4 single nucleotide polymorphisms with P≤5.0E-07 and additional 119 ones with 5.0E-07<P≤5.0E-05. These markers were located throughout all chromosomes. The largest numbers were found on porcine chromosomes 6 and 9 (n=15), 4 (n=13), and 7 (n=12) while the most significant marker was located on chromosome 18. Twenty-two single nucleotide polymorphisms were in intronic regions of genes already recognized by the Pre-Ensembl Sscrofa10.2 assembly. Gene Ontology analysis indicated an enrichment of Gene Ontology terms associated with nervous system development and regulation in concordance with results of large genome wide association studies for human obesity. CONCLUSIONS: Further investigations are needed to evaluate the effects of the identified single nucleotide polymorphisms associated with backfat thickness on other traits as a pre-requisite for practical applications in breeding programs. Reported results could improve our understanding of the biology of fat metabolism and deposition that could also be relevant for other mammalian species including humans, confirming the role of neuronal genes on obesity.To June 10, 2013 the paper is labelled as "Highly accessed" on the BMC genomics website http://www.biomedcentral.com/1471-2164/13/583openFontanesi L;Schiavo G;Galimberti G;Calò DG;Scotti E;Martelli PL;Buttazzoni L;Casadio R;Russo VFontanesi L;Schiavo G;Galimberti G;Calò DG;Scotti E;Martelli PL;Buttazzoni L;Casadio R;Russo

    LARGE Volume String Compactifications at Finite Temperature

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    We present a detailed study of the finite-temperature behaviour of the LARGE Volume type IIB flux compactifications. We show that certain moduli can thermalise at high temperatures. Despite that, their contribution to the finite-temperature effective potential is always negligible and the latter has a runaway behaviour. We compute the maximal temperature TmaxT_{max}, above which the internal space decompactifies, as well as the temperature TT_*, that is reached after the decay of the heaviest moduli. The natural constraint T<TmaxT_*<T_{max} implies a lower bound on the allowed values of the internal volume V\mathcal{V}. We find that this restriction rules out a significant range of values corresponding to smaller volumes of the order V104ls6\mathcal{V}\sim 10^{4}l_s^6, which lead to standard GUT theories. Instead, the bound favours values of the order V1015ls6\mathcal{V}\sim 10^{15}l_s^6, which lead to TeV scale SUSY desirable for solving the hierarchy problem. Moreover, our result favours low-energy inflationary scenarios with density perturbations generated by a field, which is not the inflaton. In such a scenario, one could achieve both inflation and TeV-scale SUSY, although gravity waves would not be observable. Finally, we pose a two-fold challenge for the solution of the cosmological moduli problem. First, we show that the heavy moduli decay before they can begin to dominate the energy density of the Universe. Hence they are not able to dilute any unwanted relics. And second, we argue that, in order to obtain thermal inflation in the closed string moduli sector, one needs to go beyond the present EFT description.Comment: 54 pages + appendix, 5 figures; v2: minor corrections, references and footnotes added, version published on JCA

    Non Abelian Geometrical Tachyon

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    We investigate the dynamics of a pair of coincident D5 branes in the background of kk NS5 branes. It has been proposed by Kutasov that the system with a single probing D-brane moving radially in this background is dual to the tachyonic DBI action for a non-BPS Dp brane. We extend this proposal to the non-abelian case and find that the duality still holds provided one promotes the radial direction to a matrix valued field associated with a non-abelian geometric tachyon and a particular parametrization for the transverse scalar fields is chosen. The equations of motion of a pair of coincident D5 branes moving in the NS5 background are determined. Analytic and numerical solutions for the pair are found in certain simplified cases in which the U(2) symmetry is broken to U(1)×U(1)U(1) \times U(1) corresponding to a small transverse separation of the pair. For certain range of parameters these solutions describe periodic motion of the centre of mass of the pair 'bouncing off' a finite sized throat whose minimum size is limited by the D5 branes separation.Comment: 18 pages, 2 figures, PdfLatex: references added.accepted for publication in JHE

    O'KKLT at Finite Temperature

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    We study whether finite temperature corrections decompactify the internal space in KKLT compactifications with an uplifting sector given by a system that exhibits metastable dynamical supersymmetry breaking. More precisely, we calculate the one-loop temperature corrections to the effective potential of the volume modulus in the KKLT model coupled to the quantum corrected O'Raifeartaigh model. We prove that for the original KKLT model, namely with one exponent in the non-perturbative superpotential, the finite temperature potential is runaway when at zero temperature there is a dS minimum. On the other hand, for a non-perturbative superpotential of the race-track type with two exponents, we demonstrate that the temperature-dependent part of the effective potential can have local minima at finite field vevs. However, rather unexpectedly, it turns out that these minima do not affect the structure of the full effective potential and so the volume modulus is stabilized at the local minimum of the zero temperature potential for the whole range of validity of the supergravity approximation.Comment: 33 pages; minor corrections, journal versio

    Lack of the Nlrp3 Inflammasome Improves Mice Recovery Following Traumatic Brain Injury

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    Treatment for traumatic brain injury (TBI) remains elusive despite compelling evidence from animal models for a variety of therapeutic targets. The activation of the NLRP3 (Nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing 3) inflammasome has been proposed as key point in the brain damage associated with TBI. NLRP3 was tested as potential target for reducing neuronal loss and promoting functional recovery in a mouse model of TBI. Male NLRP3-/- (n = 20) and wild type (n = 27) mice were used. A closed TBI model was performed and inflammatory and apoptotic markers were evaluated. A group of WT mice also received BAY 11-7082, a NLRP3 inhibitor, to further evaluate the role of this pathway. At 24 h following TBI NLRP3-/- animals demonstrated a preserved cognitive function as compared to WT mice, additionally brain damage was less severe and the inflammatory mediators were reduced in brain lysates. The administration of BAY 11-7082 in WT animals subjected to TBI produced overlapping results. At day 7 histology revealed a more conserved brain structure with reduced damage in TBI NLRP3-/- animals compared to WT. Our data indicate that the NLRP3 pathway might be exploited as molecular target for the short-term sequelae of TBI
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