Flux Modulations seen by the Muon Veto of the GERDA Experiment

The GERDA experiment at LNGS of INFN is equipped with an active muon veto. The main part of the system is a water Cherenkov veto with 66~PMTs in the water tank surrounding the GERDA cryostat. The muon flux recorded by this veto shows a seasonal modulation. Two effects have been identified which are caused by secondary muons from the CNGS neutrino beam (2.2 %) and a temperature modulation of the atmosphere (1.4 %). A mean cosmic muon rate of $I^0_{\mu} = (3.477 \pm 0.002_{\textrm{stat}} \pm 0.067_{\textrm{sys}}) \times 10^{-4}$/(s$\cdot$m$^2$) was found in good agreement with other experiments at LNGS at a depth of 3500~meter water equivalent.Comment: 7 pages, 6 figure

Limit on the Radiative Neutrinoless Double Electron Capture of 36^{36}Ar from GERDA Phase I

Neutrinoless double electron capture is a process that, if detected, would give evidence of lepton number violation and the Majorana nature of neutrinos. A search for neutrinoless double electron capture of $^{36}$Ar has been performed with germanium detectors installed in liquid argon using data from Phase I of the GERmanium Detector Array (GERDA) experiment at the Gran Sasso Laboratory of INFN, Italy. No signal was observed and an experimental lower limit on the half-life of the radiative neutrinoless double electron capture of $^{36}$Ar was established: $T_{1/2} >$ 3.6 $\times$ 10$^{21}$ yr at 90 % C.I.Comment: 7 pages, 3 figure

Prevalence of Drug-Resistant HIV-1 Variants in Untreated Individuals in Europe: Implications for Clinical Management

BackgroundInfection with drug-resistant human immunodeficiency virus type 1 (HIV-1) can impair the response to combination therapy. Widespread transmission of drug-resistant variants has the disturbing potential of limiting future therapy options and affecting the efficacy of postexposure prophylaxis penta increase-spacing 1>MethodsWe determined the baseline rate of drug resistance in 2208 therapy-naive patients recently and chronically infected with HIV-1 from 19 European countries during 1996-2002 ResultsIn Europe, 1 of 10 antiretroviral-naive patients carried viruses with ⩾1 drug-resistance mutation. Recently infected patients harbored resistant variants more often than did chronically infected patients (13.5% vs. 8.7%; P=.006). Non-B viruses (30%) less frequently carried resistance mutations than did subtype B viruses (4.8% vs. 12.9%; P<.01). Baseline resistance increased over time in newly diagnosed cases of non-B infection: from 2.0% (1/49) in 1996-1998 to 8.2% (16/194) in 2000-2001 ConclusionsDrug-resistant variants are frequently present in both recently and chronically infected therapy-naive patients. Drug-resistant variants are most commonly seen in patients infected with subtype B virus, probably because of longer exposure of these viruses to drugs. However, an increase in baseline resistance in non-B viruses is observed. These data argue for testing all drug-naive patients and are of relevance when guidelines for management of postexposure prophylaxis and first-line therapy are update

Genetic risk and a primary role for cell-mediated immune mechanisms in multiple sclerosis.

Multiple sclerosis is a common disease of the central nervous system in which the interplay between inflammatory and neurodegenerative processes typically results in intermittent neurological disturbance followed by progressive accumulation of disability. Epidemiological studies have shown that genetic factors are primarily responsible for the substantially increased frequency of the disease seen in the relatives of affected individuals, and systematic attempts to identify linkage in multiplex families have confirmed that variation within the major histocompatibility complex (MHC) exerts the greatest individual effect on risk. Modestly powered genome-wide association studies (GWAS) have enabled more than 20 additional risk loci to be identified and have shown that multiple variants exerting modest individual effects have a key role in disease susceptibility. Most of the genetic architecture underlying susceptibility to the disease remains to be defined and is anticipated to require the analysis of sample sizes that are beyond the numbers currently available to individual research groups. In a collaborative GWAS involving 9,772 cases of European descent collected by 23 research groups working in 15 different countries, we have replicated almost all of the previously suggested associations and identified at least a further 29 novel susceptibility loci. Within the MHC we have refined the identity of the HLA-DRB1 risk alleles and confirmed that variation in the HLA-A gene underlies the independent protective effect attributable to the class I region. Immunologically relevant genes are significantly overrepresented among those mapping close to the identified loci and particularly implicate T-helper-cell differentiation in the pathogenesis of multiple sclerosis

Keeping the background low: production and testing of the GERDA Phase II detectors

The GERmanium Detector Array (GERDA) experiment at the INFN Laboratori Nazionali del Gran Sasso searches for neutrinoless double beta decay of 76Ge. The first phase using ∼15 kg of coaxial germanium detectors is ongoing. In a second phase, additional ∼20 kg of newly produced Broad Energy Germanium (BEGe) detectors will be deployed. To limit the generation of cosmogenically induced radioisotopes, the exposure of the germanium to cosmic radiation during the detector production and testing was minimized. An acceptance and characterization campaign of the newly produced detectors was carried out at the HEROICA facility in the HADES underground laboratory in Mol, Belgium. An overview over the complete production process, from isotopic enrichment of the material to the detector testing protocol, is given

Integrating simulations and hands-on activities in physics pre-service teacher education

Simulations are a valuable tool in teaching modern science. We report on an experiment in a physics laboratory on electricity using both simulations as well as hands-on activities. The laboratory was implemented as part of a course for pre- service secondary school physics teachers. The 45 participants were divided into two groups, one performing first simulations and then hands-on activities, the other in the reversed order. The laboratory activities focused on DC circuits related to real-life situations, like a multiple socket or a chandelier modeled with simple wires, batteries and bulbs. The participants were asked to make predictions of the outcome before conducting each task and to compare their predictions with the observations and measurements they made during the activities. No significant differences in performance were observed between the two groups, suggesting that in this experiment simulations did not help the pre-service teachers in transferring their conceptual knowledge to practical application

Physics for gifted children: A laboratory experience for primary- and middle-school students.

In the framework of Education to Talent 2, an initiative addressing the subject of gifted children and their problems in adapting to the educational system, a one-day physics laboratory for gifted primary- and middle-school students was organized. Aspects like fast pace, understanding of concepts, and inquiry, crucial ingredients when creating stimulating learning environments for gifted children, were considered in the design of the laboratory activities. This communication gives a detailed description and evaluation of the experiences encountered in the laboratory unit on electricity and discusses the critical points in view of an extension of the approach in regular classrooms

PLS - Progetto ESTAGE: uno sguardo al passato per comprendere il futuro della ricerca in fisica e astronomia

Il contributo descrive il progetto ESTAGE organizzato all'interno del Piano Lauree Scientifiche e che riguarda stage estivi residenziali per studenti del quarto anno delle superiori proposti dal Dipartimento di Fisica e Astronomia dell'Universit\ue0 di Padova in collaborazione con gli enti di ricerca INFN e INAF. L'organizzazione delle attivit\ue0 permette agli studenti di conoscere da vicino il mondo della ricerca scientifica, ma anche di riflettere sull'evoluzione delle conoscenze scientifiche e sui rapporti complessi e articolati che esistono tra scienza e tecnica

Determination of dead-layer variation in HPGe detectors

The dead-layer uniformity of the top surface of two high purity germanium detectors has been studied using a novel automated scanning set-up that allows a fine-grained topography of a detector's top and lateral surfaces. Comparisons between measurements and Monte Carlo simulations allowed implementation of a dead-layer variation into the detector model, which reproduces the measurements results. The effect of the non-uniform dead-layer on activity determinations based on low-energy gamma-rays (i.e. below 100 key) has been determined to be of the order of 10% or more. (C) 2013 Elsevier Ltd. All rights reserved