471 research outputs found

    The VLT-FLAMES Tarantula Survey XXI. Stellar spin rates of O-type spectroscopic binaries

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    The initial distribution of spin rates of massive stars is a fingerprint of their elusive formation process. It also sets a key initial condition for stellar evolution and is thus an important ingredient in stellar population synthesis. So far, most studies have focused on single stars. Most O stars are however found in multiple systems. By establishing the spin-rate distribution of a sizeable sample of O-type spectroscopic binaries and by comparing the distributions of binary sub-populations with one another as well as with that of presumed single stars in the same region, we aim to constrain the initial spin distribution of O stars in binaries, and to identify signatures of the physical mechanisms that affect the evolution of the massive stars spin rates. We use ground-based optical spectroscopy obtained in the framework of the VLT-FLAMES Tarantula Survey (VFTS) to establish the projected equatorial rotational velocities (\vrot) for components of 114 spectroscopic binaries in 30 Doradus. The \vrot\ values are derived from the full-width at half-maximum (FWHM) of a set of spectral lines, using a FWHM vs. \vrot\ calibration that we derive based on previous line analysis methods applied to single O-type stars in the VFTS sample. The overall \vrot\ distribution of the primary stars resembles that of single O-type stars in the VFTS, featuring a low-velocity peak (at \vrot < 200 kms) and a shoulder at intermediate velocities (200 < \vrot < 300 kms). The distributions of binaries and single stars however differ in two ways. First, the main peak at \vrot \sim100 kms is broader and slightly shifted toward higher spin rates in the binary distribution compared to that of the presumed-single stars. Second, the \vrot distribution of primaries lacks a significant population of stars spinning faster than 300 kms while such a population is clearly present in the single star sample.Comment: 16 pages, 16 figures, paper accepted in Astronomy & Astrophysic

    An Introduction and High Yield Summary of Female Contraceptive Methods

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    Globally, contraceptive studies and their use are major challenges in the realm of public health. The ideal goal is to obtain a contraceptive method that is highly effective at minimizing unplanned pregnancies and nullifying the chance of contracting a sexually transmitted disease. Abstinence is currently the only way to attain such a dualistic goal, and while effective, it may not be suitable for sexually active individuals. While there is an abundance of methodspecific information regarding the use of any one female contraceptive device, there is a paucity of resources that compare and contrast the advantages and disadvantages of such methods and enable an individual to optimize family planning. This paper attempts to address many of these topics by reviewing a multitude of U.S. Food and Drug Administration (FDA) approved contraceptive methods. This work is intentionally written towards educating medical students, educators and teachers at all levels of training with foundational knowledge regarding female contraception

    Continuous propofol perfusion in critically ill children

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    Objetivo: Describir la sedación con perfusión continua de propofol en ni˜nos en estado crítico. Dise˜no: Estudio observacional descriptivo retrospectivo. Ámbito: Unidad de cuidados intensivos pediátricos. Pacientes: Pacientes que requirieron sedoanalgesia entre el 1 de octubre de 2009 y el 30 de septiembre de 2010. Intervenciones: Ninguna. Variables recogidas: Demográficas, clínicas, de laboratorio, diagnóstico, tratamiento, complicaciones y evolución de cada paciente. Se analizaron los posibles efectos adversos asociados a la administración de propofol, comparando el grupo de pacientes a los que se les administró con el resto de los ni˜nos críticos. Resultados: Recibieron propofol en perfusión continua 71 de los 222 pacientes recogidos (32%). Los fármacos sedoanalgésicos más utilizados fueron el midazolam, seguido del fentanilo y del propofol. La dosis media de propofol fue de 2,1 mg/kg/h [desviación estándar (DE) 1,3, rango: 0,5-6)] y la duración media de 6,7 días (DE 8,5; rango: 0,5-40). La edad media fue de 45,8 meses (mediana 24; rango intercuartil: 7-65), siendo el 52% varones. Ningún paciente presentó síndrome de infusión por propofol ni otros efectos adversos graves. Los pacientes tratados con propofol presentaron con mayor frecuencia algunas alteraciones analíticas que el resto, pero no se demostró relación causa efecto con la administración del fármaco. No existieron diferencias significativas en los niveles de lactato ni en la incidencia de infecciones entre ambos grupos. Conclusión: el propofol a una dosis de 1 a 4 mg/kg/h puede utilizarse como un fármaco alternativo para la sedación de mantenimiento en los ni˜nos críticamente enfermos. Sin embargo son necesarios más estudios que valoren su eficacia y seguridad.Q3Q3Artículo original410-415Objective: To describe sedation with continuous perfusion of propofol in critically ill children. Design: A retrospective, descriptive observational study was carried out. Setting: A pediatric intensive care unit. Patients: Pediatric patients requiring sedoanalgesia between October 1, 2009 and September 30, 2010. Interventions: None. Data collected: Demographic, clinical and laboratory test variables, diagnosis, treatment, complications and evolution in each patient. In addition, the potential adverse effects associated with propofol administration were analyzed. Results: Midazolam, fentanyl and propofol were the most commonly used sedative and analgesic drugs. Seventy-one out of 222 patients (32%) received propofol in continuous infusion. The average dose was 2.1 mg/kg/h (SD 1.3, range: 0.5 to 6), and the average duration of treatment was of 6.7 days (SD 8.5 range 0.5---40). Fifty-two percent were males, and the mean patient age was 45.8 months (median: 24; interquartile range: 7-65). No patient developed propofol infusion syndrome or other serious drug-related adverse effects. Patients treated with propofol showed more abnormal laboratory test findings, although no relationship to drug administration could be demonstrated. There were no significant differences in lactate level or in the incidence of infection in either group. Conclusions: Propofol at a dose of 1 to 4 mg/kg/h is a safe alternative for sustained sedation in critically ill children. However, further studies are needed to assess its effects and safety profile

    Larval fish dispersal in a coral-reef seascape

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    Free to read at publisher's site. Larval dispersal is a critical yet enigmatic process in the persistence and productivity of marine metapopulations. Empirical data on larval dispersal remain scarce, hindering the use of spatial management tools in efforts to sustain ocean biodiversity and fisheries. Here we document dispersal among subpopulations of clownfish (Amphiprion percula) and butterflyfish (Chaetodon vagabundus) from eight sites across a large seascape (10,000 km(2)) in Papua New Guinea across 2 years. Dispersal of clownfish was consistent between years, with mean observed dispersal distances of 15 km and 10 km in 2009 and 2011, respectively. A Laplacian statistical distribution (the dispersal kernel) predicted a mean dispersal distance of 13-19 km, with 90% of settlement occurring within 31-43 km. Mean dispersal distances were considerably greater (43-64 km) for butterfly-fish, with kernels declining only gradually from spawning locations. We demonstrate that dispersal can be measured on spatial scales sufficient to inform the design of and test the performance of marine reserve networks

    The invisible enemy : Understanding bird-window strikes through citizen science in a focal city

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    Bird-window collisions have been estimated to be among the most important sources of bird death. Despite increasing knowledge in Latin America, our understanding of this phenomenon is still incipient, with research performed in Mexico limited to a handful of studies. Here, we present the results of a citizen science effort focused on bird-window collisions at seven buildings in the university campus of the National School of Higher Studies (ENES) of the National Autonomous University of Mexico, located in the city of Leon (central Mexico). Our main goal was to describe seasonal patterns of bird-window collisions and their relationship with building traits (i.e., building height, window area) through citizen science monitoring strategies. Our results showed that collisions were higher in two of the seven studied buildings, with two bird species recording almost half of the total collisions: Clay-colored Sparrow (Spizella pallida) and Indigo Bunting (Passerina cyanea). Seasonally, April was the only month to differ from the rest of the studied months, showing significantly higher rate of bird-window collision. Regarding building traits, only building height was related to the number of recorded bird-window collisions. In sum, our study provides findings from an understudied area, showing the value of citizen science approaches to generate knowledge on a deadly phenomenon. Notably, besides the potential drawbacks and importance of generating this kind of information, our project raised awareness on the topic across the entire campus community, from the students and academics to the administration, highlighting the potential for social impact with these kinds of projects.Peer reviewe

    Sickness presenteeism in Spanish-born and immigrant workers in Spain

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    <p>Abstract</p> <p><b>Background</b></p> <p>Previous studies have shown that immigrant workers face relatively worse working and employment conditions, as well as lower rates of sickness absence than native-born workers. This study aims to assess rates of sickness presenteeism in a sample of Spanish-born and foreign-born workers according to different characteristics.</p> <p>Methods</p> <p>A cross-sectional survey was conducted amongst a convenience sample of workers (Spanish-born and foreign-born), living in four Spanish cities: Barcelona, Huelva, Madrid and Valencia (2008-2009). Sickness presenteeism information was collected through two items in the questionnaire ("Have you had health problems in the last year?" and "Have you ever had to miss work for any health problem?") and was defined as worker who had a health problem (answered yes, first item) and had not missed work (answered no, second item). For the analysis, the sample of 2,059 workers (1,617 foreign-born) who answered yes to health problems was included. After descriptives, logistic regressions were used to establish the association between origin country and sickness presenteeism (adjusted odds ratios aOR; 95% confidence interval 95%CI). Analyses were stratified per time spent in Spain among foreign-born workers.</p> <p>Results</p> <p>All of the results refer to the comparison between foreign-born and Spanish-born workers as a whole, and in some categories relating to personal and occupational conditions. Foreign-born workers were more likely to report sickness presenteeism compared with their Spanish-born counterparts, especially those living in Spain for under 2 years [Prevalence: 42% in Spanish-born and 56.3% in Foreign-born; aOR 1.77 95%CI 1.24-2.53]. In case of foreign-born workers (with time in Spain < 2 years), men [aOR 2.31 95%CI 1.40-3.80], those with university studies [aOR 3.01 95%CI 1.04-8.69], temporary contracts [aOR 2.26 95%CI 1.29-3.98] and salaries between 751-1,200€ per month [aOR 1.74 95% CI 1.04-2.92] were more likely to report sickness presenteeism. Also, recent immigrants with good self-perceived health and good mental health were more likely to report presenteeism than Spanish-born workers with the same good health indicators.</p> <p>Conclusions</p> <p>Immigrant workers report more sickness presenteeism than their Spanish-born counterparts. These results could be related to precarious work and employment conditions of immigrants. Immigrant workers should benefit from the same standards of social security, and of health and safety in the workplace that are enjoyed by Spanish workers.</p

    The VLT-FLAMES Tarantula Survey XVIII. Classifications and radial velocities of the B-type stars

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    We present spectral classifications for 438 B-type stars observed as part of the VLT-FLAMES Tarantula Survey (VFTS) in the 30 Doradus region of the Large Magellanic Cloud. Radial velocities are provided for 307 apparently single stars, and for 99 targets with radial-velocity variations which are consistent with them being spectroscopic binaries. We investigate the spatial distribution of the radial velocities across the 30 Dor region, and use the results to identify candidate runaway stars. Excluding potential runaways and members of two older clusters in the survey region (SL 639 and Hodge 301), we determine a systemic velocity for 30 Dor of 271.6 ± 12.2 kms-1 from 273 presumed single stars. Employing a 3σ criterion we identify nine candidate runaway stars (2.9% of the single stars with radial-velocity estimates). The projected rotational velocities of the candidate runaways appear to be significantly different to those of the full B-type sample, with a strong preference for either large (≥345 kms-1) or small (≤65 kms-1) rotational velocities. Of the candidate runaways, VFTS 358 (classified B0.5: V) has the largest differential radial velocity (−106.9 ± 16.2 kms-1), and a preliminary atmospheric analysis finds a significantly enriched nitrogen abundance of 12 + log (N/H) ≳ 8.5. Combined with a large rotational velocity (ve sin i = 345 ± 22 kms-1), this is suggestive of past binary interaction for this star

    Adopting transfer learning for neuroimaging: a comparative analysis with a custom 3D convolution neural network model

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    Background: In recent years, neuroimaging with deep learning (DL) algorithms have made remarkable advances in the diagnosis of neurodegenerative disorders. However, applying DL in different medical domains is usually challenged by lack of labeled data. To address this challenge, transfer learning (TL) has been applied to use state-of-the-art convolution neural networks pre-trained on natural images. Yet, there are differences in characteristics between medical and natural images, also image classification and targeted medical diagnosis tasks. The purpose of this study is to investigate the performance of specialized and TL in the classification of neurodegenerative disorders using 3D volumes of 18F-FDG-PET brain scans. Results: Results show that TL models are suboptimal for classification of neurodegenerative disorders, especially when the objective is to separate more than two disorders. Additionally, specialized CNN model provides better interpretations of predicted diagnosis. Conclusions: TL can indeed lead to superior performance on binary classification in timely and data efficient manner, yet for detecting more than a single disorder, TL models do not perform well. Additionally, custom 3D model performs comparably to TL models for binary classification, and interestingly perform better for diagnosis of multiple disorders. The results confirm the superiority of the custom 3D-CNN in providing better explainable model compared to TL adopted ones

    Caribbean Corals in Crisis: Record Thermal Stress, Bleaching, and Mortality in 2005

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    BACKGROUND The rising temperature of the world's oceans has become a major threat to coral reefs globally as the severity and frequency of mass coral bleaching and mortality events increase. In 2005, high ocean temperatures in the tropical Atlantic and Caribbean resulted in the most severe bleaching event ever recorded in the basin. METHODOLOGY/PRINCIPAL FINDINGS Satellite-based tools provided warnings for coral reef managers and scientists, guiding both the timing and location of researchers' field observations as anomalously warm conditions developed and spread across the greater Caribbean region from June to October 2005. Field surveys of bleaching and mortality exceeded prior efforts in detail and extent, and provided a new standard for documenting the effects of bleaching and for testing nowcast and forecast products. Collaborators from 22 countries undertook the most comprehensive documentation of basin-scale bleaching to date and found that over 80% of corals bleached and over 40% died at many sites. The most severe bleaching coincided with waters nearest a western Atlantic warm pool that was centered off the northern end of the Lesser Antilles. CONCLUSIONS/SIGNIFICANCE Thermal stress during the 2005 event exceeded any observed from the Caribbean in the prior 20 years, and regionally-averaged temperatures were the warmest in over 150 years. Comparison of satellite data against field surveys demonstrated a significant predictive relationship between accumulated heat stress (measured using NOAA Coral Reef Watch's Degree Heating Weeks) and bleaching intensity. This severe, widespread bleaching and mortality will undoubtedly have long-term consequences for reef ecosystems and suggests a troubled future for tropical marine ecosystems under a warming climate.This work was partially supported by salaries from the NOAA Coral Reef Conservation Program to the NOAA Coral Reef Conservation Program authors. NOAA provided funding to Caribbean ReefCheck investigators to undertake surveys of bleaching and mortality. Otherwise, no funding from outside authors' institutions was necessary for the undertaking of this study. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

    The effect of perceived discrimination on the health of immigrant workers in Spain

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    Background: Discrimination is an important determinant of health inequalities, and immigrants may be more vulnerable to certain types of discrimination than the native-born. This study analyses the relationship between immigrants' perceived discrimination and various self-reported health indicators. Methods: A cross-sectional survey was conducted (2008) amongst a non-random sample of 2434 immigrants from Ecuador, Morocco, Romania and Colombia in four Spanish cities: Barcelona, Huelva, Madrid and Valencia. A factorial analysis of variables revealed three dimensions of perceived discrimination (due to immigrant status, due to physical appearance, and workplace-related). The association of these dimensions with self-rated health, mental health (GHQ-12), change in self-rated health between origin and host country, and other self-reported health outcomes was analysed. Logistic regression was used adjusting for potential confounders (aOR-95%CI). Subjects with worsening self-reported health status potentially attributable to perceived discrimination was estimated (population attributable proportion, PAP %). Results: 73.3% of men and 69.3% of women immigrants reported discrimination due to immigrant status. Moroccans showed the highest prevalence of perceived discrimination. Immigrants reporting discrimination were at significantly higher risk of reporting health problems than those not reporting discrimination. Workplace-related discrimination was associated with poor mental health (aOR 2.97 95%CI 2.45-3.60), and the worsening of self-rated health (aOR 2.20 95%CI 1.73- 2.80). 40% (95% CI 24-53) PAP of those reporting worse self-rated health could be attributable to discrimination due to immigrant status. Conclusions: Discrimination may constitute a risk factor for health in immigrant workers in Spain and could explain some health inequalities among immigrant populations in Spanish society.This work was supported by the following sources: Carolina Foundation (Spain), Healthcare Research Fund of the Spanish Ministry of Health and Consumption (references PI050497, PI052202, PI052334, PI061701, and PI0790470
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