479 research outputs found
Study of sequential semileptonic decays of b hadrons produced at the Tevatron
We present a study of rates and kinematical properties of lepton pairs
contained in central jets with transverse energy E_T > 15 GeV that are produced
at the Fermilab Tevatron collider. We compare the data to a QCD prediction
based on the HERWIG and QQ Monte Carlo generator programs.We find that the data
are poorly described by the simulation, in which sequential semileptonic decays
of single b quarks (b --> l c X with c --> l s X) are the major source of such
lepton pairs.Comment: 25 pages, 8 figures. Some typos were fixed in the text and
bibliography. Submitted to Phys. Rev.
Phenomenological study of the atypical heavy flavor production observed at the Fermilab Tevatron
We address known discrepancies between the heavy flavor properties of jets
produced at the Tevatron collider and the prediction of conventional-QCD
simulations. In this study, we entertain the possibility that these effects are
real and due to new physics. We show that all anomalies can be simultaneously
fitted by postulating the additional pair production of light bottom squarks
with a 100% semileptonic branching fraction.Comment: 30 pages, 13 figures, 3 tables. Submitted to Phys. Rev.
Towards Master Data Management for Cultural Heritage: the Sacri Monti web platform
This paper focuses on managing the Cultural Heritage maintenance process through web platforms, exploring a data-driven new approach that relies on the framework of Master Data Management (MDM). The MDM framework is based on data quality, revisioning and auditing of information, and the Microsoft SQL Server Master Data Services (MDS) was used. It is a highly customizable commercial tool that proved to be effective and able to manage extended and articulated databases and provide stability and long-term software support. MDS provides powerful tools to avoid duplicates, ensure data quality, and record all the modifications that occurred on the dataset over time. These are key features to build a reliable platform for information management of complex CH assets. The paper presents some first tests applied for the Sacri Monti of Piedmont and Lombardy case of study. It is a UNESCO wide religious architectural complex site in northern Italy’s mountainous part. The paper compares approaches and previous experiences of Sacri Monti management using web platform information systems, such as the BIM3DSG, Chimera, and Main10ance, to support Sacri Monti management activity
Calibration of thickness-dependent k-factors for germanium X-ray lines to improve energy-dispersive X-ray spectroscopy of SiGe layers in analytical transmission electron microscopy
We show that the accuracy of energy-dispersive X-ray spectroscopy can be improved by analysing and comparing multiple lines from the same element. For each line, an effective k-factor can be defined that varies as a function of the intensity ratio of multiple lines (e.g. K/L) from the same element. This basically performs an internal self-consistency check in the quantification using differently absorbed X-ray lines, which is in principle equivalent to an absorption correction as a function of specimen thickness but has the practical advantage that the specimen thickness itself does not actually need to be measured
Exoskeletons for workers: A case series study in an enclosures production line
This case-series study aims to investigate the effects of a passive shoulder support exoskeleton on experienced workers during their regular work shifts in an enclosures production site. Experimental activities included three sessions, two of which were conducted in-field (namely, at two workstations of the painting line, where panels were mounted and dismounted from the line; each session involved three participants), and one session was carried out in a realistic simulated environment (namely, the workstations were recreated in a laboratory; this session involved four participants). The effect of the exoskeleton was evaluated through electromyographic activity and perceived effort. After in-field sessions, device usability and user acceptance were also assessed. Data were reported individually for each participant. Results showed that the use of the exoskeleton reduced the total shoulder muscular activity compared to normal working conditions, in all subjects and experimental sessions. Similarly, the use of the exoskeleton resulted in reductions of the perceived effort in the shoulder, arm, and lower back. Overall, participants indicated high usability and acceptance of the device. This case series invites larger validation studies, also in diverse operational contexts
Lower limb deep vein thrombosis in COVID-19 patients admitted to intermediate care respiratory units
COVID-19 has been associated with an increased risk of thrombotic events; however, the reported incidence of deep vein thrombosis varies depending, at least in part, on the severity of the disease. Aim of this prospective, multicenter, observational study was to investigate the incidence of lower limb deep vein thrombosis as assessed by compression ultrasound in consecutive patients admitted to three pulmonary medicine wards designated to care for patients with COVID-19 related pneumonia, with or without respiratory failure but not requiring admission to an intensive care unit. Consecutive patients admitted between March 27 and May 6, 2020 were enrolled. Patients were excluded if they were less than 18-year-old or if compression ultrasound could not be performed for any reason. Patients were assessed at admission (t0) and after 7 days (t1). Major and non-major clinically relevant bleedings were recorded. Sixty-eight patients were enrolled. Two were excluded due to anatomical abnormalities that prevented compression ultrasound; sixty patients were retested at (t1). All patients were started on antithrombotic prophylaxis, unless therapeutic anticoagulation was required. Deep vein thrombosis as assessed by compression ultrasound was observed in 2 patients (3%); one of them was later deemed to represent a previous episode. No new episodes were detected at t1. One major and 2 non-major clinically relevant bleedings were observed. In the setting of patients with COVID-related pneumonia not requiring admission to an intensive care unit, the incidence of deep vein thrombosis is low and our data support not screening asymptomatic patients
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