With the aim of measuring the 235U(n,f) cross section at the n_TOF facility at CERNover a wide neutron energy range, a detection system consisting of two fission detectors and threedetectors for ...neutron flux determination was realized. The neutron flux detectors are RecoilProton Telescopes (RPTs), based on scintillators and solid state detectors, conceived to detectrecoil protons from the neutron-proton elastic scattering reaction. This system, along with afission chamber and an array of parallel plate avalanche counters for fission event detection, wasinstalled for the measurement at the n_TOF facility in 2018, at CERN. An overview of the performances of two RPTs — especially developed for this measurement — and of theparallel plate avalanche counters are described in this article. In particular, the characterizationin terms of detection efficiency by Monte Carlo simulations and response to neutron beam, the studyof the background, dead time correction and characterization of the samples, are reported. Theresults of the present investigation show that the performances of these detectors are suitable foraccurate measurements of fission reaction cross sections in the range from 10 to 450 MeV.
Water has supposedly marked the surface of Mars and produced characteristic landforms. To understand the history of water on Mars, we take a close look at key locations with the High-Resolution ...Imaging Science Experiment on board the Mars Reconnaissance Orbiter, reaching fine spatial scales of 25 to 32 centimeters per pixel. Boulders ranging up to ~2 meters in diameter are ubiquitous in the middle to high latitudes, which include deposits previously interpreted as finegrained ocean sediments or dusty snow. Bright gully deposits identify six locations with very recent activity, but these lie on steep (20° to 35°) slopes where dry mass wasting could occur. Thus, we cannot confirm the reality of ancient oceans or water in active gullies but do see evidence of fluvial modification of geologically recent mid-latitude gullies and equatorial impact craters.
Introduction
Metabolic syndrome (MetS) is a cluster of components including abdominal obesity, hyperglycemia, hypertension, and dyslipidemia. MetS is highly prevalent in individuals with bipolar ...disorders (BD) with an estimated global rate of 32.6%. Longitudinal data on incident MetS in BD are scarce and based on small sample size. The objectives of this study were to estimate the incidence of MetS in a large longitudinal cohort of 1521 individuals with BD and to identify clinical and biological predictors of incident MetS.
Methods
Participants were recruited from the FondaMental Advanced Center of Expertise for Bipolar Disorder (FACE‐BD) cohort and followed‐up for 3 years. MetS was defined according to the International Diabetes Federation criteria. Individuals without MetS at baseline but with MetS during follow‐up were considered as having incident MetS. A logistic regression model was performed to estimate the adjusted odds ratio and its corresponding 95% confidence interval (CI) for an association between each factor and incident MetS during follow‐up. We applied inverse probability‐of‐censoring weighting method to minimize selection bias due to loss during follow‐up.
Results
Among individuals without MetS at baseline (n = 1521), 19.3% developed MetS during follow‐up. Multivariable analyses showed that incident MetS during follow‐up was significantly associated with male sex (OR = 2.2, 95% CI = 1.7–3.0, p < 0.0001), older age (OR = 2.14, 95% CI = 1.40–3.25, p = 0.0004), presence of a mood recurrence during follow‐up (OR = 1.91, 95% CI = 1.22–3.00, p = 0.0049), prolonged exposure to second‐generation antipsychotics (OR = 1.56, 95% CI = 0.99, 2.45, p = 0.0534), smoking status at baseline (OR = 1.30, 95% CI = 1.00–1.68), lifetime alcohol use disorders (OR = 1.33, 95% CI = 0.98–1.79), and baseline sleep disturbances (OR = 1.04, 95% CI = 1.00–1.08), independently of the associations observed for baseline MetS components.
Conclusion
We observed a high incidence of MetS during a 3 years follow‐up (19.3%) in individuals with BD. Identification of predictive factors should help the development of early interventions to prevent or treat early MetS.
The increasing use of composite materials for lightweight structural applications and the extended tailoring capabilities offered by variable stiffness laminates requires rapid and robust analysis ...tools that adequately describe the mechanical behaviour of such structures. In this work, a Rayleigh–Ritz solution for generally restrained multilayered stiffened variable angle tow plates in the post-buckling regime is presented. The plate model is based on first-order shear deformation theory and accounts for geometrical nonlinearity through von Kármán’s assumptions. General symmetric and unsymmetric stacking sequences are considered and Legendre orthogonal polynomials are employed to approximate the unknown displacement field. Stiffened variable angle tow plates are modeled as an assembly of plate-like elements and penalty techniques are used to enforce the displacements continuity of the assembled multidomain structure and also to apply the kinematical boundary conditions. The developed postbuckling analysis is sufficiently versatile to model a wide range of configurations and load cases for multi-component, variable angle tow, composite structures, and provide the same accuracy level as finite element analysis. The proposed solution is validated by comparison with literature and finite elements analysis and original results are presented for the thermo-mechanical post-buckling solution of multilayered stiffened variable angle tow plates. The effectiveness of the developed analysis tool for both stiffened plates and a tapered stiffened wing box is shown, with a reduced number of unknowns and simplified data preparation compared to finite element analysis.
With the aim of measuring the $^{235}$U(n,f) cross section at the n_TOF facility at CERN over a wide neutron energy range, a detection system consisting of two fission detectors and three detectors ...for neutron flux determination was realized. The neutron flux detectors are Recoil Proton Telescopes (RPT), based on scintillators and solid state detectors, conceived to detect recoil protons from the neutron-proton elastic scattering reaction. This system, along with a fission chamber and an array of parallel plate avalanche counters for fission event detection, was installed for the measurement at the n_TOF facility in 2018, at CERN. An overview of the performances of two RPTs - especially developed for this measurement - and of the parallel plate avalanche counters are described in this article. In particular, the characterization in terms of detection efficiency by Monte Carlo simulations and response to neutron beam, the study of the background, dead time correction and characterization of the samples, are reported. The results of the present investigation show that the performances of these detectors are suitable for accurate measurements of fission reaction cross sections in the range from 10 to 450~MeV.
Although preventive strategies have been proposed against catheter-associated urinary tract infections (CAUTIs) in intensive care units (ICUs), more efforts are needed to control the incidence rate.
...To distinguish patients according to their characteristics at ICU admission, and to identify clusters of patients at higher risk for CAUTIs.
A two-step cluster analysis was conducted on 9656 patients from the Italian Nosocomial Infections Surveillance in Intensive Care Units project.
Three clusters of patients were identified. Type of admission, patient origin and administration of antibiotics had the greatest weight on the clustering model. Cluster 1 comprised more patients with a medical type of ICU admission who came from the community. Cluster 2 comprised patients who were more likely to come from other wards/hospitals, and to report administration of antibiotics 48 h before or after ICU admission. Cluster 3 was similar to Cluster 2 but was characterized by a lower percentage of patients with administration of antibiotics 48 h before or after ICU admission. Patients in Clusters 1 and 2 had a longer duration of urinary catheterization median 7 days, interquartile range (IQR) 12 days for Cluster 1; median 7 days, IQR 11 days for Cluster 2 than patients in Cluster 3 (median 6 days, IQR 8 days; P<0.001). Interestingly, patients in Cluster 1 had a higher incidence of CAUTIs (3.5 per 100 patients) compared with patients in the other two clusters (2.5 per 100 patients in both clusters; P=0.033).
To the authors' knowledge, this is the first study to use cluster analysis to identify patients at higher risk of CAUTIs who could gain greater benefit from preventive strategies.
The energy-dependent cross section of the Be7(n,alpha)He4 reaction, of interest for the so-called cosmological lithium problem in big bang nucleosynthesis, has been measured for the first time from ...10 meV to 10 keV neutron energy. The challenges posed by the short half-life of Be7 and by the low reaction cross section have been overcome at n_TOF thanks to an unprecedented combination of the extremely high luminosity and good resolution of the neutron beam in the new experimental area (EAR2) of the n_TOF facility at CERN, the availability of a sufficient amount of chemically pure Be7, and a specifically designed experimental setup. Coincidences between the two alpha particles have been recorded in two Si-Be7-Si arrays placed directly in the neutron beam. The present results are consistent, at thermal neutron energy, with the only previous measurement performed in the 1960s at a nuclear reactor. The energy dependence reported here clearly indicates the inadequacy of the cross section estimates currently used in BBN calculations. Although new measurements at higher neutron energy may still be needed, the n_TOF results hint at a minor role of this reaction in BBN, leaving the long-standing cosmological lithium problem unsolved.
Pulse shape analysis of liquid scintillators for neutron studies Marrone, S; Cano-Ott, D; Colonna, N ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
09/2002, Letnik:
490, Številka:
1
Journal Article
Recenzirano
The acquisition of signals from liquid scintillators with Flash ADC of high sampling rate
(1
GS/
s)
has been investigated. The possibility to record the signal waveform is of great advantage in ...studies with γ's and neutrons in a high count-rate environment, as it allows to easily identify and separate pile-up events. The shapes of pulses produced by γ-rays and neutrons have been studied for two different liquid scintillators, NE213 and C
6D
6. A 1-parameter fitting procedure is proposed, which allows to extract information on the particle type and energy. The performance of this method in terms of energy resolution and n/γ discrimination is analyzed, together with the capability to identify and resolve pile-up events.
The OSIRIS‐REx Asteroid Sample Return Mission is the third mission in National Aeronautics and Space Administration (NASA)'s New Frontiers Program and is the first U.S. mission to return samples from ...an asteroid to Earth. The most important decision ahead of the OSIRIS‐REx team is the selection of a prime sample‐site on the surface of asteroid (101955) Bennu. Mission success hinges on identifying a site that is safe and has regolith that can readily be ingested by the spacecraft's sampling mechanism. To inform this mission‐critical decision, the surface of Bennu is mapped using the OSIRIS‐REx Camera Suite and the images are used to develop several foundational data products. Acquiring the necessary inputs to these data products requires observational strategies that are defined specifically to overcome the challenges associated with mapping a small irregular body. We present these strategies in the context of assessing candidate sample sites at Bennu according to a framework of decisions regarding the relative safety, sampleability, and scientific value across the asteroid's surface. To create data products that aid these assessments, we describe the best practices developed by the OSIRIS‐REx team for image‐based mapping of irregular small bodies. We emphasize the importance of using 3‐D shape models and the ability to work in body‐fixed rectangular coordinates when dealing with planetary surfaces that cannot be uniquely addressed by body‐fixed latitude and longitude.
Plain Language Summary
The OSIRIS‐REx Asteroid Sample Return Mission must map asteroid (101955) Bennu using the OSIRIS‐REx Camera Suite. Here we present the techniques that are established to accomplish this goal. Mapping helps us find the best place on the surface of Bennu from which to gather a sample. Because asteroids are small bodies with weak gravitational fields, maneuvering a spacecraft around them can be challenging. Considering these complexities, we have found ways to gather images of Bennu needed for creating maps. Additionally, due to the irregular shape of many asteroids, producing 2‐D maps in terms of latitude and longitude may be insufficient for describing their surface geography. To that end, we have developed software that is capable of creating and displaying image maps in 3‐D.
Key Points
The OSIRIS‐REx Asteroid Sample Return Mission performs image‐based mapping of (101955) Bennu to aid in the selection of a sample‐site
We develop observational strategies to perform mapping to address the challenges associated with surveying a small body
We identify pitfalls and best practices for mapping images of small bodies with large concavities, elongated axes, or overhanging terrain
Abstract To obtain a direct sensorimotor integration assessment in primary hand cortical areas (M1) of patients suffering from focal task-specific hand dystonia, magnetoencephalographic (MEG) and ...opponens pollicis electromyographic (EMG) activities were acquired during a motor task expressly chosen not to induce dystonic movements in our patients, to disentangle abnormalities indicating a possible substrate on which dystonia develops. A simple isometric contraction was performed either alone or in combination with median nerve stimulation, i.e. when a non-physiological sensory inflow was overlapping with the physiological feedback. As control condition, median nerve stimulation was also performed at rest. The task was performed bilaterally both in eight patients and in 16 healthy volunteers. In comparison with results in controls we found that in dystonic patients: i) MEG-EMG coherence was higher; ii) it reduced much less during galvanic stimulation in the hemisphere contralateral to the dystonic arm, simultaneously with iii) stronger inhibition of the sensory areas responsiveness due to movement; iv) the cortical component including contributions from sensory inhibitory and motor structures was reduced and v) much more inhibited during movement. It is documented that a simultaneous cortico-muscular coherence increase occurs in presence of a reduced M1 responsiveness to the inflow from the sensory regions. This could indicate an unbalance of the fronto-parietal functional impact on M1, with a weakening of the parietal components. Concurrently, signs of a less differentiated sensory hand representation—possibly due to impaired inhibitory mechanisms efficiency—and signs of a reduced repertoire of voluntary motor control strategies were found.
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