1,484 research outputs found

    Computer modeling of large asteroid impacts into continental and oceanic sites: Atmospheric, cratering, and ejecta dynamics

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    Numerous impact cratering events have occurred on the Earth during the last several billion years that have seriously affected our planet and its atmosphere. The largest cratering events, which were caused by asteroids and comets with kinetic energies equivalent to tens of millions of megatons of TNT, have distributed substantial quantities of terrestrial and extraterrestrial material over much or all of the Earth. In order to study a large-scale impact event in detail, computer simulations were completed that model the passage of a 10 km-diameter asteroid through the Earth's atmosphere and the subsequent cratering and ejecta dynamics associated with impact of the asteroid into two different targets, i.e., an oceanic site and a continental site. The calcuations were designed to broadly represent giant impact events that have occurred on the Earth since its formation and specifically represent an impact cratering event proposed to have occurred at the end of Cretaceous time. Calculation of the passage of the asteroid through a U.S. Standard Atmosphere showed development of a strong bow shock that expanded radially outward. Behind the shock front was a region of highly shock compressed and intensely heated air. Behind the asteroid, rapid expansion of this shocked air created a large region of very low density that also expanded away from the impact area. Calculations of the cratering events in both the continental and oceanic targets were carried to 120 s. Despite geologic differences, impacts in both targets developed comparable dynamic flow fields, and by approx. 29 s similar-sized transient craters approx. 39 km deep and approx. 62 km across had formed. For all practical purposes, the atmosphere was nearly completely removed from the impact area for tens of seconds, i.e., air pressures were less than fractions of a bar out to ranges of over 50 km. Consequently, much of the asteroid and target materials were ejected upward into a near vacuum. Effects of secondary volcanism and return of the ocean over hot oceanic crater floor could also be expected to add substantial solid and vaporized material to the atmosphere, but these conditions were not studied

    SinEx DB: a database for single exon coding sequences in mammalian genomes

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    Indexación: Web of Science.Eukaryotic genes are typically interrupted by intragenic, noncoding sequences termed introns. However, some genes lack introns in their coding sequence (CDS) and are generally known as 'single exon genes' (SEGs). In this work, a SEG is defined as a nuclear, protein-coding gene that lacks introns in its CDS. Whereas, many public databases of Eukaryotic multi-exon genes are available, there are only two specialized databases for SEGs. The present work addresses the need for a more extensive and diverse database by creating SinEx DB, a publicly available, searchable database of predicted SEGs from 10 completely sequenced mammalian genomes including human. SinEx DB houses the DNA and protein sequence information of these SEGs and includes their functional predictions (KOG) and the relative distribution of these functions within species. The information is stored in a relational database built with My SQL Server 5.1.33 and the complete dataset of SEG sequences and their functional predictions are available for downloading. SinEx DB can be interrogated by: (i) a browsable phylogenetic schema, (ii) carrying out BLAST searches to the in-house SinEx DB of SEGs and (iii) via an advanced search mode in which the database can be searched by key words and any combination of searches by species and predicted functions. SinEx DB provides a rich source of information for advancing our understanding of the evolution and function of SEGs.https://academic.oup.com/database/article-lookup/doi/10.1093/database/baw09

    Development and delivery of a physiotherapist-led exercise intervention in a randomised controlled trial for subacromial impingement syndrome (the SUPPORT trial)

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    Purpose This paper describes the development, content and delivery of a physiotherapist- led individualised, supervised and progressed exercise programme for use in a factorial randomised controlled trial testing treatments for subacromial impingement syndrome. Methods To develop the intervention, a survey of community physiotherapists and national guidelines provided the basis for a consensus workshop through which a protocol was developed for the SUPPORT trial physiotherapist-led exercise programme (SUPPORT: SUbacromial impingement syndrome and Pain: a randomised controlled trial Of exeRcise and injection). The protocol included three stages of exercise progression: (1) scapular stability and active exercise with no resistance (2) range of motion exercise with scapular control, isometrics and stretches, and (3) through range resistance exercise. A two day training programme was developed for physiotherapists which included the trial background, current evidence and strategies to improve exercise adherence. Results Twenty physiotherapists were trained to deliver the exercise intervention. In the SUPPORT trial, 128 participants were randomised to physiotherapist-led exercise. Ninety nine (81%) participants had their first physiotherapy session within 2 to 3 weeks and 71 (56%) received six to eight treatment sessions. Frequently-used exercises were: stage 1 scapular setting with glenohumeral joint (GHJ) flexion to 90°, stage 2 GHJ medial rotation stretch, stage 3 scapular setting through lateral rotation, with resistance bands. Conclusion We combined clinical and research expertise with national guidance in order to develop a physiotherapist-led, individualised, progressed and supervised exercise intervention for use within a randomised trial. The effectiveness of the intervention is being evaluated within the SUPPORT trial

    Decline in an Atlantic Puffin population : evaluation of magnitude and mechanisms

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    Funding: This study was funded annually by Fair Isle Bird Observatory Trust (www.fairislebirdobs.co.uk) with contributions from the Joint Nature Conservation Committee (jncc.defra.gov.uk). Funding was received from these two sources by Fair Isle Bird Observatory from 1986 to 2013. The Joint Nature Conservation Committee and Fair Isle Bird Observatory Trust supplied guidance on study design, data collection, analyses, preparation of the manuscript and the decision to publish.Peer reviewedPublisher PD

    Feasibility, drug safety, and effectiveness of etiological treatment programs for Chagas disease in Honduras, Guatemala, and Bolivia: 10-year experience of Médecins Sans Frontières

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    BACKGROUND: Chagas disease (American trypanosomiasis) is a zoonotic or anthropozoonotic disease caused by the parasite Trypanosoma cruzi. Predominantly affecting populations in poor areas of Latin America, medical care for this neglected disease is often lacking. Médecins Sans Frontières/Doctors Without Borders (MSF) has provided diagnostic and treatment services for Chagas disease since 1999. This report describes 10 years of field experience in four MSF programs in Honduras, Guatemala, and Bolivia, focusing on feasibility protocols, safety of drug therapy, and treatment effectiveness. METHODOLOGY: From 1999 to 2008, MSF provided free diagnosis, etiological treatment, and follow-up care for patients <18 years of age seropositive for T. cruzi in Yoro, Honduras (1999-2002); Olopa, Guatemala (2003-2006); Entre Ríos, Bolivia (2002-2006); and Sucre, Bolivia (2005-2008). Essential program components guaranteeing feasibility of implementation were information, education, and communication (IEC) at the community and family level; vector control; health staff training; screening and diagnosis; treatment and compliance, including family-based strategies for early detection of adverse events; and logistics. Chagas disease diagnosis was confirmed by testing blood samples using two different diagnostic tests. T. cruzi-positive patients were treated with benznidazole as first-line treatment, with appropriate counseling, consent, and active participation from parents or guardians for daily administration of the drug, early detection of adverse events, and treatment withdrawal, when necessary. Weekly follow-up was conducted, with adverse events recorded to assess drug safety. Evaluations of serological conversion were carried out to measure treatment effectiveness. Vector control, entomological surveillance, and health education activities were carried out in all projects with close interaction with national and regional programs. RESULTS: Total numbers of children and adolescents tested for T. cruzi in Yoro, Olopa, Entre Ríos, and Sucre were 24,471, 8,927, 7,613, and 19,400, respectively. Of these, 232 (0.9%), 124 (1.4%), 1,475 (19.4%), and 1,145 (5.9%) patients, respectively, were diagnosed as seropositive. Patients were treated with benznidazole, and early findings of seroconversion varied widely between the Central and South American programs: 87.1% and 58.1% at 18 months post-treatment in Yoro and Olopa, respectively; 5.4% by up to 60 months in Entre Ríos; and 0% at an average of 18 months in Sucre. Benznidazole-related adverse events were observed in 50.2% and 50.8% of all patients treated in Yoro and Olopa, respectively, and 25.6% and 37.9% of patients in Entre Ríos and Sucre, respectively. Most adverse events were mild and manageable. No deaths occurred in the treatment population. CONCLUSIONS: These results demonstrate the feasibility of implementing Chagas disease diagnosis and treatment programs in resource-limited settings, including remote rural areas, while addressing the limitations associated with drug-related adverse events. The variability in apparent treatment effectiveness may reflect differences in patient and parasite populations, and illustrates the limitations of current treatments and measures of efficacy. New treatments with improved safety profiles, pediatric formulations of existing and new drugs, and a faster, reliable test of cure are all urgently needed

    Des caractéristiques de la goutte associées à la dépression mais pas à l’anxiété en soins primaires : conclusions initiales d’une étude de cohorte prospective

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    Objectifs Déterminer la prévalence de l’anxiété et de la dépression dans le contexte de la goutte, examiner les liens entre certaines caractéristiques de la goutte et ces comorbidités et identifier le rôle de l’allopurinol dans ces relations. Méthodes Dans le cadre d’une étude de cohorte prospective, un questionnaire initial a été envoyé à 1805 participants goutteux âgés de 18 ans et plus et patients de cabinets de soins primaires britanniques. Ont été retenus les patients dont le dossier médical faisant mention d’un diagnostic de goutte ou de prescriptions d’allopurinol ou de colchicine deux ans avant le début de l’étude. La prévalence de l’anxiété a été définie au moyen du questionnaire sur le trouble d’anxiété généralisée (TAG) et celle de la dépression, par l’auto-questionnaire Patient Health Questionnaire (PHQ). Une analyse par régression logistique a été réalisée pour explorer les éventuelles associations entre les caractéristiques de la goutte (fréquence des crises sur 12 mois, goutte oligo/polyarticulaire et durée de la maladie) et l’anxiété ou la dépression. Les associations brutes et après ajustement ont été exprimées en odds ratio (OR) et intervalle de confiance (IC) 95 %. Les caractéristiques de la goutte ajustées ont été stratifiées en fonction de la prise d’allopurinol. Résultats Au total, 1184 participants (65,6 %) ont répondu au questionnaire initial. La prévalence de l’anxiété et de la dépression était respectivement de 10,0 % et de 12,6 %. Aucune association n’a été observée entre les caractéristiques de la goutte et l’anxiété. Toutefois, la fréquence des crises et la dépression ont été associées chez les patients goutteux sous allopurinol (OR 2,87 [IC 95 % 1,2 à 6,6]) et un lien a également été relevé entre la goutte oligo/polyarticulaire et la dépression (2,01 [1,3][1,2 à 3,3]), aussi bien chez les patients sous allopurinol (2,09 [1,1 à 4,0]) que chez ceux n’en prenant pas (2,64 [1,8][1,0 à 6,8]). Conclusion Les patients souffrant de crises de goutte fréquentes ou touchant plusieurs articulations sont susceptibles de présenter des symptômes dépressifs même lorsqu’ils prennent de l’allopurinol. La dépression peut influencer l’observance du traitement et la participation aux examens de routine, ce qui se répercute négativement sur les résultats de la prise en charge de la goutte

    Deep Impact Mission to Tempel 1 Favours New Explosive Cosmogony of Comets

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    The assumption that short-period (SP) comets are fragments of massive icy envelopes of Ganymede-like bodies saturated by products of ice electrolysis that underwent global explosions provides a plausible explanation of all known manifestations of comets, including the jet character of outflows, the presence of ions in the vicinity of the nucleus, the bursts and splitting of cometary nuclei, etc., with solar radiation initiating burning of the products of electrolysis in the nucleus. As shown persuasively by numerical simulation carried out in hydrodynamic approximation, the shock wave initiated by the Deep Impact (DI) impactor in the cometary ice saturated originally by the electrolysis products 2H2 + O2 is capable of activating under certain conditions exothermal reactions (of the type O2 + H2 + organics = H2O + CO + HCN + other products of incomplete burning of organics including its light and heavy pyrolyzed compounds, soot, etc.), which will slow down shock wave damping (forced detonation) and increase many times the energy release. As a result, the measured energetics of ejections and outflows from the crater have to exceed the DI energetics. Analysis of different clusters of the DI experiment data confirms these conclusions and expectations and thus it favours the planetary origin of comets.Comment: 21 pages incluging 3 figure
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