Numerical study of heat transfer in a distorted rod bundle

The effect of rod distortion on the flow and heat transfer in a rod (fuel) bundle similar to those in an Advanced Gas-cooled Reactor (AGR) is investigated using carefully constructed CFD models. The results are of relevance to various other engineering applications, for example heat exchangers. The distorted element contracts gradually over the first half of the element, reaching a minimum at half high then subsequently increasing back to its normal value over the second half of the element. In this paper, the results for forced convection are presented. Changes in the rod profiles divert flow to regions of less resistance, resulting in strong cross flow recirculation regions. The resultant three dimensional flow is also accompanied by large scale swirling flow around the fuel pins. The hotspot at any height coincides with the leeward side of the cross flow. It is rather surprising that the peak can temperature at the location of worst bundle distortion (i.e middle height) is actually slightly lower than that of intact fuel. The overall peak can temperature in the damaged bundle is however much higher than that in the intact fuel, and this occurs towards the top of the bundle

Beam commissioning of the 35 MeV section in an intensity modulated proton linear accelerator for proton therapy

This paper presents the experimental results on the Terapia Oncologica con Protoni-Intensity Modulated Proton Linear Accelerator (TOP-IMPLART) beam that is currently accelerated up to 35 MeV, with a final target of 150 MeV. The TOP-IMPLART project, funded by the Innovation Department of Regione Lazio (Italy), is led by Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA) in collaboration with the Italian Institute of Health and the Oncological Hospital Regina Elena-IFO. The accelerator, under construction and test at ENEA-Frascati laboratories, employs a commercial 425 MHz, 7 MeV injector followed by a sequence of 3 GHz accelerating modules consisting of side coupled drift tube linac (SCDTL) structures up to 71 MeV and coupled cavity linac structures for higher energies. The section from 7 to 35 MeV, consisting on four SCDTL modules, is powered by a single 10 MW klystron and has been successfully commissioned. This result demonstrates the feasibility of a “fully linear” proton therapy accelerator operating at a high frequency and paves the way to a new class of machines in the field of cancer treatment

The Top-Implart Proton Linear Accelerator: Interim Characteristics of the 35 Mev Beam

In the framework of the Italian TOP-IMPLART project (Regione Lazio), ENEA-Frascati, ISS and IFO are developing and constructing the first proton linear accelerator based on an actively scanned beam for tumor radiotherapy with final energy of 150 MeV. An important feature of this accelerator is modularity: an exploitable beam can be delivered at any stage of its construction, which allows for immediate characterization and virtually continuous improvement of its performance. Currently, a sequence of 3 GHz accelerating modules combined with a commercial injector operating at 425 MHz delivers protons up to 35 MeV. Several dosimetry systems were used to obtain preliminary characteristics of the 35-MeV beam in terms of stability and homogeneity. Short-term stability and homogeneity better than 3% and 2.6%, respectively, were demonstrated; for stability an improvement with respect to the respective value obtained for the previous 27 MeV beam

Genome-wide signatures of complex introgression and adaptive evolution in the big cats.

The great cats of the genus Panthera comprise a recent radiation whose evolutionary history is poorly understood. Their rapid diversification poses challenges to resolving their phylogeny while offering opportunities to investigate the historical dynamics of adaptive divergence. We report the sequence, de novo assembly, and annotation of the jaguar (Panthera onca) genome, a novel genome sequence for the leopard (Panthera pardus), and comparative analyses encompassing all living Panthera species. Demographic reconstructions indicated that all of these species have experienced variable episodes of population decline during the Pleistocene, ultimately leading to small effective sizes in present-day genomes. We observed pervasive genealogical discordance across Panthera genomes, caused by both incomplete lineage sorting and complex patterns of historical interspecific hybridization. We identified multiple signatures of species-specific positive selection, affecting genes involved in craniofacial and limb development, protein metabolism, hypoxia, reproduction, pigmentation, and sensory perception. There was remarkable concordance in pathways enriched in genomic segments implicated in interspecies introgression and in positive selection, suggesting that these processes were connected. We tested this hypothesis by developing exome capture probes targeting ~19,000 Panthera genes and applying them to 30 wild-caught jaguars. We found at least two genes (DOCK3 and COL4A5, both related to optic nerve development) bearing significant signatures of interspecies introgression and within-species positive selection. These findings indicate that post-speciation admixture has contributed genetic material that facilitated the adaptive evolution of big cat lineages

Musculoskeletal injuries among operating room nurses: results from a multicenter survey in Rome, Italy

Aim: Chronic disorders of the musculoskeletal system, particularly low back pain (LBP), are increasing and represent a social and economic problem of growing importance, especially if correlated with working conditions. Health care workers are at higher risk of developing LBP during work shifts in the hospital. The aim of this study was to assess the prevalence of LBP among operating room nurses and to investigate the risk factors for musculoskeletal injuries in the operating room. Methods: We carried out a cross-sectional study that included operating room nurses from nine hospitals. Information on sociodemographic characteristics, lifestyle habits, working activity and psychological attitude of nurses was collected using an anonymous self-administered structured questionnaire. We evaluated the association of frequency, localization and intensity of LBP (FLI) with qualitative variables, making use of univariate analysis, chi-square test and Fisher's exact test. Multiple logistic regression analysis was performed to identify the variables that affected the FLI. The covariates included in the model were the variables that had a p 35 years vs. age <35 (OR = 2.68; 95% CI = 1.17–6.18) and diurnal work shift vs. diurnal/ nocturnal (OR = 4.00; 95% CI = 1.72–9.0) represent risk factors associated with FLI, while physical activity is a protective factor (OR = 0.47; 95% CI = 0.20–1.08). Conclusion: The data suggest that it is important to promote new programs of prevention based on professional training and physical activity among nurses and to improve the organization of work shifts in the hospital

Public, private and personal: Qualitative research on policymakers' opinions on smokefree interventions to protect children in 'private' spaces

<p>Abstract</p> <p>Background</p> <p>Governments use law to constrain aspects of private activities for purposes of protecting health and social wellbeing. Policymakers have a range of perceptions and beliefs about what is public or private. An understanding of the possible drivers of policymaker decisions about where government can or should intervene for health is important, as one way to better guide appropriate policy formation. Our aim was to identify obstacles to, and opportunities for, government smokefree regulation of private and public spaces to protect children. In particular, to seek policymaker opinions on the regulation of smoking in homes, cars and public parks and playgrounds in a country with incomplete smokefree laws (New Zealand).</p> <p>Methods</p> <p>Case study, using structured interviews to ask policymakers (62 politicians and senior officials) about their opinions on new smokefree legislation for public and private places. Supplementary data was obtained from the Factiva media database, on the views of New Zealand local authority councillors about policies for smokefree outdoor public places.</p> <p>Results</p> <p>Overall, interviewees thought that government regulation of smoking in private places was impractical and unwise. However, there were some differences on what <it>was </it>defined as 'private', particularly for cars. Even in public parks, smoking was seen by some as a 'personal' decision, and unlikely to be amenable to regulation. Most participants believed that educative, supportive and community-based measures were better and more practical means of reducing smoking in private places, compared to regulation.</p> <p>Conclusions</p> <p>The constrained view of the role of regulation of smoking in public and private domains may be in keeping with current political discourse in New Zealand and similar Anglo-American countries. Policy and advocacy options to promote additional smokefree measures include providing a better voice for childrens' views, increasing information to policymakers about the harms to children from secondhand smoke and the example of adult smoking, and changing the culture for smoking around children.</p