14,340 research outputs found

    Reconstruction of α\alpha-attractor supergravity models of inflation

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    In this paper, we apply reconstruction techniques to recover the potential parameters for a particular class of single-field models, the α\alpha-attractor (supergravity) models of inflation. This also allows to derive the inflaton vacuum expectation value at horizon crossing. We show how to use this value as one of the input variables to constrain the postaccelerated inflationary phase. We assume that the tensor-to-scalar ratio rr is of the order of 10310^{-3} , a level reachable by the expected sensitivity of the next-generation CMB experiments.Comment: 10 pages, LaTeX, some typos correcte

    Constraining auto-interaction terms in α-attractor supergravity models of inflation

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    The inflationary mechanism has become the paradigm of modern cosmology over the last thirty years. However, there are several aspects of inflationary physics that are still to be addressed, like the shape of the inflationary potential. Regarding this, the so-called α-attractor models show interesting properties. In this work, the reconstruction of the effective potential around the global minimum of these particular potentials is provided, assuming a detection of permille-order for the tensor-to-scalar-ratio by forthcoming cosmic microwave background or gravitational waves experiments

    Rotational sensitivity of the "G-Pisa" gyrolaser

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    G-Pisa is an experiment investigating the possibility to operate a high sensitivity laser gyroscope with area less than 1m21 \rm m^2 for improving the performances of the mirrors suspensions of the gravitational wave antenna Virgo. The experimental set-up consists in a He-Ne ring laser with a 4 mirrors square cavity. The laser is pumped by an RF discharge where the RF oscillator includes the laser plasma in order to reach a better stability. The contrast of the Sagnac fringes is typically above 50% and a stable regime has been reached with the laser operating both single mode or multimode. The effect of hydrogen contamination on the laser was also checked. A low-frequency sensitivity, below 1Hz1 \rm Hz, in the range of 108(rad/s)/Hz10^{-8} \rm {(rad / s)/ \sqrt{Hz}} has been measured.Comment: 6 pages, 6 figures, presented at the EFTF-IFCS joint conference 200

    Slow-roll Inflation for Generalized Two-Field Lagrangians

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    We study the slow-roll regime of two field inflation, in which the two fields are also coupled through their kinetic terms. Such Lagrangians are motivated by particle physics and by scalar-tensor theories studied in the Einstein frame. We compute the power spectra of adiabatic and isocurvature perturbations on large scales to first order in the slow-roll parameters. We discuss the relevance of the extra coupling terms for the amplitude and indexes of the power spectra. Beyond the consistency condition which involves the amplitude of gravitational waves, additional relations may be found in particular models based on such Lagrangians: as an example, we find an additional general consistency condition in implicit form for Brans-Dicke theory in the Einstein frame.Comment: 17 pages, 1 figure, accepted for publication in Phys. Rev.

    Evolution of Large Scale Curvature Fluctuations During the Perturbative Decay of the Inflaton

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    We study the evolution of cosmological fluctuations during and after inflation driven by a scalar field coupled to a perfect fluid through afriction term. During the slow-roll regime for the scalar field, the perfect fluid is also frozen and isocurvature perturbations are generated. After the end of inflation, during the decay of the inflaton, we find that a change in the observationally relevant large scale curvature fluctuations is possible.Comment: 9 pages, 2 figures; v2: version published in PR

    Operation of EMEP ‘supersites’ in the United Kingdom. Annual report for 2008.

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    As part of its commitment to the UN-ECE Convention on Long-range Transboundary Air Pollution the United Kingdom operates two ‘supersites’ reporting data to the Co-operative Programme for Monitoring and Evaluation of the Long-range Transmission of Air Pollutants in Europe (EMEP). This report provides the annual summary for 2008, the second full calendar year of operation of the first EMEP ‘supersite’ to be established in the United Kingdom. Detailed operational reports have been submitted to Defra every 3 months, with unratified data. This annual report contains a summary of the ratified data for 2008. The EMEP ‘supersite’ is located in central southern Scotland at Auchencorth (3.2oW, 55.8oN), a remote rural moorland site ~20 km south-west of Edinburgh. Monitoring operations started formally on 1 June 2006. In addition to measurements made specifically under this contract, the Centre for Ecology & Hydrology also acts as local site operator for measurements made under other UK monitoring networks: the Automated Urban and Rural Network (AURN), the UK Eutrophication and Acidification Network (UKEAP), the UK Hydrocarbons Network, and the UK Heavy Metals Rural Network. Some measurements were also made under the auspices of the ‘Air Pollution Deposition Processes’ contract. All these associated networks are funded by Defra. This report summarises the measurements made between January and December 2008, and presents summary statistics on average concentrations. The site is dominated by winds from the south-west, but wind direction data highlight potential sources of airborne pollutants (power stations, conurbations). The average diurnal patterns of gases and particles are consistent with those expected for a remote rural site. The frequency distributions are presented for data where there was good data capture throughout the whole period. Some components (e.g. black carbon) show log-normal frequency distributions, while other components (e.g. ozone) have more nearly normal frequency distributions. A case study is presented for a period in June 2008, showing the influence of regional air pollutants at this remote rural site. All the data reported under the contract are shown graphically in the Appendix

    HCV-1b intra-subtype variability: Impact on genetic barrier to protease inhibitors

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    Due to error-prone RNA polymerase and the lack of proofreading mechanisms, to the spread worldwide and probable long-term presence in human population, HCV showed a high degree of inter- and intra-subtype genetic variability. Protease inhibitors (PIs), a new class of drugs, have been designed specifically on the HCV genotype 1 NS3 protease three-dimensional structure. The viral genetic barrier limits the efficacy of PIs, and fourteen loci in the HCV NS3 gene are involved in resistance to PIs. A sensitive method (15UI/ml) for study the HCV genetic profile of 125 strains from patients naïve to PIs, was developed through the use of new degenerate primers for subtype 1b. We observed the presence of naturally resistance-associated variants in 14% of the HCV strains (V36L, F43S, T54S, I153V, R155Q, D168A/G). T54S was the most common mutation (4%) detected. We investigated, through minimal score (m.s.) calculating, how the HCV intra-subtype 1b variability modifies the genetic barrier to PIs. For >60% of strains a single transition (m.s. of 1) was required for selection of low to medium resistance mutations, while more than one transition/transversion (m.s. ⩾2.5) or one transition plus one transversion (m.s. ⩾3.5) was necessary for most of the high level PI-resistant-associated mutations, except for A156V, for which a single transition was sufficient (m.s. of 1). However, the presence at locus 36 of the amino acid polymorphism S36 in one case and the wild type V36 in 6 isolates, encoded by unusual GTA or GTG codons, might determined a higher probability of V36L/M mutations because of the reduction of the genetic barrier. Instead, the presence of the CGA and CGT codons in the 155(th) position increases the genetic barrier for R155M or R155Q/M. The large intra-subtype variability, suggests that a routine baseline resistance test must be used before PIs-treatment

    Phylogenetic Analysis of isolates from new cases of HBV infection in Southern Italy.

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    The level of endemicity of hepatitis B virus (HBV) infections in Italy is low and genotype D infections predominant. New HBV strains may however be introduced as a result of movements of people from regions of high endemicity. The aim of the present study was to determine whether strains from new cases of acute hepatitis B detected in southern Italy were due to endemic or new HBV strains. We studied 34 isolates from patients with acute hepatitis B infection, and 35 from chronic hepatitis B patients. A phylogenetic analysis of preS/S region was done by comparing the sequences from the acute and chronic cases with references sequences. The study showed that 44% of strain from acute hepatitis B patients were of genotype A, 53% of genotype D, and 3% of genotype E. The molecular analysis of isolates from acute hepatitis B patients from Sicily showed a change in the local epidemiology of this infection, with an increase in HBV/A infections and a clustering effect for HBV D2, possibly correlated to immigration. The introduction of new genotypes , could have an effect on HBV-correlated diseases due to the different association between genotype, liver disease and response to antiviral therapy

    Focusing Strength Measurements of the Main Quadrupoles for the LHC

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    More than 1100 quadrupole magnets of different types are needed for the Large Hadron Collider (LHC) which is in the construction stage at CERN. The most challenging parameter to measure on these quadrupoles is the integrated gradient (Gdl). An absolute accuracy of 0.1% is needed to control the beta beating. In this paper we briefly describe the whole set of equipment used for Gdl measurements: Automated Scanner system, Single Stretched Wire system and Twin Coils system, concentrating mostly on their absolute accuracies. Most of the possible inherent effects that can introduce systematic errors are discussed along with their preventive methods. In the frame of this qualification some of the magnets were tested with two systems. The results of the intersystem cross-calibrations are presented. In addition, the qualification of the measurement system used at the magnet manufacturer's is based on results of more than 40 quadrupole assemblies tested in cold conditions at CERN and in warm conditions at the vendor site

    Liver eosinophilic infiltrate is a significant finding in patients with chronic hepatitis C.

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    Eosinophilic infiltrate of liver tissue is described in primary cholestatic diseases, hepatic allograft rejection and drug-induced liver injury, but its significance and its implications in chronic hepatitis C are unknown. The aim of this study was to investigate the clinical significance of eosinophilic liver infiltrate in patients with chronic hepatitis C. We retrospectively evaluated 147 patients with chronic hepatitis C. The presence of eosinophilic infiltrate was investigated in liver biopsies, and a numeric count of eosinophilic leucocytes in every portal tract was assessed. An eosinophilic infiltrate of liver tissue (≥3 cells evaluated in the portal/periportal spaces) was observed in 46 patients (31%), and patients who consumed drugs had an odds ratio (OR) of 4.02 (95% CI: 1.62-9.96) to have an eosinophilic infiltrate in liver biopsy. By logistic regression analysis, the presence of steatosis was independently associated with eosinophilic infiltrate (OR 5.86; 95% CI: 2.46-13.96) and homeostasis model assessment-score (OR 1.18; 95% CI: 1.00-1.39). Logistic regression analysis also showed that fibrosis staging ≥ 2 by Scheuer score was associated with grading >1 by Scheuer score (OR 6.82; 95% CI 2.46-18.80) and eosinophilic infiltrate (OR 4.00; 95% CI 1.23-12.91). In conclusion, we observed that the eosinophilic infiltrate of liver tissue was significantly more frequent in patients who assumed drugs, and found a significant association between eosinophilic infiltrate, liver steatosis and liver fibrosis. These preliminary data could lead to a constant assumption of drugs as a co-factor of eosinophils-mediated liver injury in chronic hepatitis
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