5,452 research outputs found
Expectations for a new calorimetric neutrino mass experiment
A large calorimetric neutrino mass experiment using thermal detectors is
expected to play a crucial role in the challenge for directly assessing the
neutrino mass. We discuss and compare here two approaches to the estimation of
the experimental sensitivity of such an experiment. The first method uses an
analytic formulation and allows to readily obtain a sensible estimate over a
wide range of experimental configurations. The second method is based on a
frequentist Montecarlo technique and is more precise and reliable. The
Montecarlo approach is then exploited to study the main sources of systematic
uncertainties peculiar to calorimetric experiments. Finally, the tools are
applied to investigate the optimal experimental configuration for a
calorimetric experiment with Rhenium based thermal detectors.Comment: 25 pagers, 16 figure
Top-N recommendations on Unpopular Items with Contextual Knowledge
Traditional recommender systems provide recommendations of items to users; recently, some of them also consider the context related to predictions. In this paper we propose a technique that relies on classical recommendation algorithms and post-filters recommendations on the basis of contextual information available for them. Association rules are exploited to identify the most significant correlations among context and item characteristics. The mined rules are used to filter the predictions performed by traditional recommender systems to provide contextualized recommendations.
Our experimental results show that the proposed approach allows improving the output of classical algorithms proposed in the literature, especially in the case of unpopular items
A bolometric measurement of the antineutrino mass
High statistics calorimetric measurements of the beta spectrum of 187Re are
being performed with arrays of silver perrhenate crystals operated at low
temperature. After a modification of the experimental set-up, which allowed to
substantially reduce the background of spurious counts and therefore to
increase the sensitivity on the electron antineutrino mass, a new measurement
with 10 silver perrhenate microbolometers is running since July 2002. The
crystals have masses between 250 and 350 micrograms and their average FWHM
energy resolution, constantly monitored by means of fluorescence X-rays, is of
28.3 eV at the beta end-point. The Kurie plot collected during 4485 hours x mg
effective running time has an end-point energy of 2466.1 +/- 0.8{stat} +/- 1.5
{syst} eV, while the half lifetime of the decay is found to be 43.2 +/-
0.2{stat} +/- 0.1{syst} Gy. These values are the most precise obtained so far
for 187Re. From the fit of the Kurie plot we can deduce a value for the squared
electron antineutrino mass m(nu)^2 of 147 +/- 237{stat} +/- 90{syst} eV^2. The
corresponding 90% C.L. upper limit for m(nu) is 21.7 eV.Comment: 3 pages, 3 figures. Submitted to Phys. Rev. Let
The 4 K outer cryostat for the CUORE experiment: construction and quality control
The external shell of the CUORE cryostat is a large cryogen-free system
designed to host the dilution refrigerator and the bolometers of the CUORE
experiment in a low radioactivity environment. The three vessels that form the
outer shell were produced and delivered to the Gran Sasso underground
Laboratories in July 2012. In this paper, we describe the production techniques
and the validation tests done at the production site in 2012.Comment: 11 pages, 13 figures; to appear in NIM
Amniotic microvesicles impact hatching and pregnancy percentages of in vitro bovine embryos and blastocyst microRNA expression versus in vivo controls
Embryo development and implantation are dynamic processes, responsive to external signals, and can potentially be influenced by many environmental factors. The aims of this study were to evaluate the effects of a culture medium supplemented with amniotic-derived microvesicles (MVs) on in vitro embryo hatching after cryopreservation, and pregnancy rate following embryo transfer. In addition, miRNA profiling of blastocysts produced in vitro, with or without (control; CTR) amniotic MV supplementation, was also evaluated using blastocysts produced in vivo. In vitro embryos were cultured with and without amniotic MV supplementation. In vivo blastocysts were obtained from superovulated cows. Samples for RNA isolation were obtained from three pools of 10 embryos each (in vivo, in vitro-CTR and in vitro + MVs). Our results show that the hatching percentage of cryopreserved in vitro + MVs embryos is higher (P < 0.05) than in vitro-CTR embryos and the pregnancy rate with fresh and cryopreserved in vitro + MVs embryos is higher than in vitro-CTR embryos. In addition, the analysis of differently expressed (DE) microRNAs showed that embryos produced in vivo are clearly different from those produced in vitro. Moreover, in vitro-CTR and in vitro + MVs embryos differ significantly for expression of two miRNAs that were found in higher concentrations in in vitro-CTR embryos. Interestingly, these two miRNAs were also reported in degenerated bovine embryos compared to good quality blastocysts. In conclusion, MV addition during in vitro production of embryos seems to counteract the adverse effect of in vitro culture and partially modulate the expression of specific miRNAs involved in successful embryo implantation
Wide band observations of the new X-ray burster SAX J1747.0-2853 during the March 1998 outburst
We report on our discovery and follow-up observations of the X-ray source SAX
J1747.0-2853 detected in outburst on 1998, March 10 with the BeppoSAX Wide
Field Cameras in the energy range 2-28 keV. The source is located about half
degree off the Galactic Nucleus. A total of 14 type-I X-ray bursts were
detected in Spring 1998, thus identifying the object as a likely low-mass X-ray
binary harboring a weakly magnetized neutron star. Evidence for photospheric
radius expansion is present in at least one of the observed bursts, leading to
an estimate of the source distance of about 9 kpc. We performed a follow-up
target of opportunity observation with the BeppoSAX Narrow Field Instruments on
March 23 for a total elapsed time of 72 ks. The source persistent luminosity
was 2.6x10^36 erg/s in the 2-10 keV energy range. The wide band spectral data
(1-200 keV) are consistent with a remarkable hard X-ray spectrum detected up to
150 keV, highly absorbed at low energies (Nh of the order of 10^23 cm^-2) and
with clear evidence for an absorption edge near 7 keV. A soft thermal component
is also observed, which can be described by single temperature blackbody
emission at about 0.6 keV.Comment: 11 pages, 3 figures, accepted for publication in ApJ Letter
Health related quality of life in COVID-19 survivors discharged from acute hospitals: results of a short-form 36-item survey [version 1; peer review: awaiting peer review]
Background: Health-related quality of life (HRQL) is important for
evaluating the impact of a disease in the longer term across the
physical and psychological domains of human functioning. The aim of
this study is to evaluate HRQL in COVID-19 survivors in Italy using the
short form 36-items questionnaire (SF-36).
Methods: This is an observational study involving adults discharged
home following a coronavirus disease 2019 (COVID-19)-related
hospital admission. Baseline demographic and clinical data including
the Cumulative Illness Rating Scale (CIRS) and the Hospital Anxiety
and Depression Scale (HADS) were collected. The validated Italian
version of SF-36 was administered cross-sectionally. The SF-36
contains eight scales measuring limitations in physical and social
functioning, the impact on roles and activities, fatigue, emotional wellbeing, pain and general health perception.
Results: A total of 35 patients, with a mean age of 60 years,
completed the SF-36. The results showed difficulties across the
physical and psychological domains, particularly affecting the return
to previous roles and activities. A higher burden of co-morbidities as
well as a more severe muscle weakness was associated to a lower
physical functioning. Younger age, rather than older, correlated to a
perceived greater limitation in physical functioning and vitality.
Conclusions: COVID-19 survivors particularly the ones of working age
may need support for resuming their premorbid level of functioning
and returning to work
Genomic and transcriptomic comparison between Staphylococcus aureus strains associated with high and low within herd prevalence of intra-mammary infection
Background: Staphylococcus aureus (Staph. aureus) is one of the major pathogens causing mastitis in dairy ruminants worldwide. The chronic nature of Staph. aureus infection enhances the contagiousness risk and diffusion in herds. In order to identify the factors involved in intra-mammary infection (IMI) and diffusion in dairy cows, we investigated the molecular characteristics of two groups of Staph. aureus strains belonging to ST8 and ST398, differing in clinical properties, through comparison of whole genome and whole transcriptome sequencing.
Results: The two groups of strains, one originated from high IMI prevalence herds and the other from low IMI prevalence herds, present a peculiar set of genes and polymorphisms related to phenotypic features, such as bacterial invasion of mammary epithelial cells and host adaptation. Transcriptomic analysis supports the high propensity of ST8 strain to chronicity of infection and to a higher potential cytotoxicity.
Conclusions: Our data are consistent with the invasiveness and host adaptation feature for the strains GTB/ST8 associated to high within-herd prevalence of mastitis. Variation in genes coding for surface exposed proteins and those associated to virulence and defence could constitute good targets for further research
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