Ubiquitous seeding of supermassive black holes by direct collapse

We study for the first time the environment of massive black hole (BH) seeds (~10^4-5 Msun) formed via the direct collapse of pristine gas clouds in massive haloes (>10^7 Msun) at z>6. Our model is based on the evolution of dark matter haloes within a cosmological N-body simulation, combined with prescriptions for the formation of BH along with both Pop III and Pop II stars. We calculate the spatially-varying intensity of Lyman Werner (LW) radiation from stars and identify the massive pristine haloes in which it is high enough to shut down molecular hydrogen cooling. In contrast to previous BH seeding models with a spatially constant LW background, we find that the intensity of LW radiation due to local sources, J_local, can be up to 10^6 times the spatially averaged background in the simulated volume and exceeds the critical value, J_crit, for the complete suppression of molecular cooling, in some cases by 4 orders of magnitude. Even after accounting for possible metal pollution in a halo from previous episodes of star formation, we find a steady rise in the formation rate of direct collapse (DC) BHs with decreasing redshift from 10^{-3}/Mpc^3/z at z=12 to 10^{-2}/Mpc^3/z at z=6. The onset of Pop II star formation at z~16 simultaneously marks the onset of the epoch of DCBH formation, as the increased level of LW radiation from Pop II stars is able to elevate the local levels of the LW intensity to J_local > J_crit while Pop III stars fail to do so at any time. The number density of DCBHs is sensitive to the number of LW photons and can vary by an order of magnitude at z=6 after accounting for reionisation feedback. Haloes hosting DCBHs are more clustered than similar massive counterparts that do not host DCBHs, especially at redshifts z>10. We also show that planned surveys with JWST should be able to detect the supermassive stellar precursors of DCBHs.Comment: 19 pages, 17 figures, v2 accepted for publication in MNRAS, minor additions in text and updates in reference

Determining minimal clinically important differences in the North Star Ambulatory Assessment (NSAA) for patients with Duchenne muscular dystrophy

The North Star ambulatory assessment (NSAA) is a functional motor outcome measure in Duchenne muscular dystrophy (DMD), widely used in clinical trials and natural history studies, as well as in clinical practice. However, little has been reported on the minimal clinically important difference (MCID) of the NSAA. The lack of established MCID estimates for NSAA presents challenges in interpreting the significance of the results of this outcome measure in clinical trials, natural history studies and clinical practice. Combining statistical approaches and patient perspectives, this study estimated MCID for NSAA using distribution-based estimates of 1/3 standard deviation (SD) and standard error of measurement (SEM), an anchor-based approach, with six-minute walk distance (6MWD) as the anchor, and evaluation of patient and parent perception using participant-tailored questionnaires. The MCID for NSAA in boys with DMD aged 7 to 10 years based on 1/3 SD ranged from 2.3-2.9 points, and that on SEM ranged from 2.9-3.5 points. Anchored on the 6MWD, the MCID for NSAA was estimated as 3.5 points. When the impact on functional abilities was considered using participant response questionnaires, patients and parent perceived a complete loss of function in a single item or deterioration of function in one to two items of the assessment as an important change. Our study examines MCID estimates for total NSAA scores using multiple approaches, including the impact of patient and parent perspective on within scale changes in items based on complete loss of function and deterioration of function, and provides new insight on evaluation of differences in these widely used outcome measure in DMD

Diagnosis, treatment and prevention of pediatric obesity: consensus position statement of the Italian Society for Pediatric Endocrinology and Diabetology and the Italian Society of Pediatrics

The Italian Consensus Position Statement on Diagnosis, Treatment and Prevention of Obesity in Children and Adolescents integrates and updates the previous guidelines to deliver an evidence based approach to the disease. The following areas were reviewed: (1) obesity definition and causes of secondary obesity; (2) physical and psychosocial comorbidities; (3) treatment and care settings; (4) prevention.The main novelties deriving from the Italian experience lie in the definition, screening of the cardiometabolic and hepatic risk factors and the endorsement of a staged approach to treatment. The evidence based efficacy of behavioral intervention versus pharmacological or surgical treatments is reported. Lastly, the prevention by promoting healthful diet, physical activity, sleep pattern, and environment is strongly recommended since the intrauterine phase

Study of an intrinsically safe infrastructure for training and research on nuclear technologies

Within European Partitioning & Transmutation research programs, infrastructures specifically dedicated to the study of fundamental reactor physics and engineering parameters of future fast-neutron-based reactors are very important, being some of these features not available in present zero-power prototypes. This presentation will illustrate the conceptual design of an Accelerator-Driven System with high safety standards, but ample flexibility for measurements. The design assumes as base option a 70MeV, 0.75mA proton cyclotron, as the one which will be installed at the INFN National Laboratory in Legnaro, Italy and a Beryllium target, with Helium gas as core coolant. Safety is guaranteed by limiting the thermal power to 200 kW, with a neutron multiplication coefficient around 0.94, loading the core with fuel containing Uranium enriched at 20% inserted in a solid-lead diffuser. The small decay heat can be passively removed by thermal radiation from the vessel. Such a system could be used to study, among others, some specific aspects of neutron diffusion in lead, beam-core coupling, target cooling and could serve as a training facility

Economic features of integral, modular, small-to-medium size reactors

The renewed interest towards nuclear energy is largely based on the escalation of fossil fuels prices and the global warming concerns. The nuclear option has to face not only the public opinion sensibility, mainly related to plant safety and waste disposal issues, but also the economic evaluation from investors and utilities, particularly careful on that energy source and in deregulated markets. Smallersize nuclear reactors (IAEA defines as “small” those reactors with power<300 MWe and “medium” with power<700 MWe) can represent a viable solution for both the stakeholders, especially for developing countries, or countries with not-highly-infrastructured and interconnected grids, or even for developed countries when limitation on capital at risk applies. A description of Small-MediumsizeReactor (SMR) economicfeatures is presented, in a comparison with the state-of-the-art Large sizeReactors. A preliminary evaluation of the capital and O&M costs shows that the negative effects of the economies of scale can be balanced by the integral and modular design strategy of SMRs

PROFESSIONAL EDUCATION IN THE FRAMEWORK OF THE EURATOM FP7 GENTLE PROJECT

The Euratom GENTLE project is a pan-European effort pulling together the leading institutions in the field of nuclear engineering and education to create a sustainable life-long learning programme in the field of nuclear fission technology. Directly targeting the needs of industry, research, regulatory and TSO organizations, three different learning programmes have been developed: 1) support for student research experiences (where graduate and undergraduate students can apply for internships at GENTLE partners), 2) inter-semester courses for undergraduate and graduate students on topics outside regular curricula (organized at partner institutes) and 3) a professional education programme (targeting professionals with at least 5 years of working experience, not necessarily in the nuclear field) that are envisioned to work in the nuclear industry. These programmes will be available for the public in 2015-2016. More information can be found at www.gentleproject.eu/.JRC.E.3-Materials researc

Pulmonary endoarterectomy in chronic thromboembolic pulmonary hypertension: short-term functional assessment in a longitudinal study.

Abstract AIM: Presently, the surgical treatment choice in chronic thromboembolic pulmonary hypertension (CTEPH) consists in a pulmonary endarterectomy (PEA). The aim of the present study is the functional assessment of patients submitted to PEA both preoperatively and shortly after the intervention. A longitudinal study was developed to study the quality and quantity of functional performance possible in these subjects. METHODS: Twenty-two subjects were assessed immediately prior to PEA and 3 months later in order to obtain quantitative measurements of short-term functional recovery. The functional assessment included the 6-min walk test (6mWT), the measurement of the oxygen percent saturation (HbS%O(2)) and the degree of dyspnea subjectively perceived by each patient. RESULTS: Three months after the surgical intervention, there was a definite increase in the number of meters walked during the 6mWT with respect to preintervention; the difference between the distances walked in the 6mWT (6mWD) in the pre and post-PEA was statistically significant (Paired t-test P<0.001). CONCLUSION: In this study the 6mWT resulted to be a useful tool in the functional evaluation of patients affected by CTEPH and submitted to PEA. The average 6mWD significantly improved already at 3 months after the intervention, thus reaching the minimum limit of the range predicted for the healthy control, but remains lower than the average theoretical value predicted (about 75% of the same)