68 research outputs found

    NuSTAR Spectroscopy of Multi-Component X-ray Reflection from NGC 1068

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    We report on observations of NGC1068 with NuSTAR, which provide the best constraints to date on its >10>10~keV spectral shape. We find no strong variability over the past two decades, consistent with its Compton-thick AGN classification. The combined NuSTAR, Chandra, XMM-Newton, and Swift-BAT spectral dataset offers new insights into the complex reflected emission. The critical combination of the high signal-to-noise NuSTAR data and a spatial decomposition with Chandra allow us to break several model degeneracies and greatly aid physical interpretation. When modeled as a monolithic (i.e., a single N_H) reflector, none of the common Compton-reflection models are able to match the neutral fluorescence lines and broad spectral shape of the Compton reflection. A multi-component reflector with three distinct column densities (e.g., N_H~1.5e23, 5e24, and 1e25 cm^{-2}) provides a more reasonable fit to the spectral lines and Compton hump, with near-solar Fe abundances. In this model, the higher N_H components provide the bulk of the Compton hump flux while the lower N_H component produces much of the line emission, effectively decoupling two key features of Compton reflection. We note that ~30% of the neutral Fe Kalpha line flux arises from >2" (~140 pc), implying that a significant fraction of the <10 keV reflected component arises from regions well outside of a parsec-scale torus. These results likely have ramifications for the interpretation of poorer signal-to-noise observations and/or more distant objects [Abridged].Comment: Submitted to ApJ; 23 pages (ApJ format); 11 figures and 3 tables; Comments welcomed

    Conservation successes and challenges for wide-ranging sharks and rays

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    Overfishing is the most significant threat facing sharks and rays. Given the growth in consumption of seafood, combined with the compounding effects of habitat loss, climate change, and pollution, there is a need to identify recovery paths, particularly in poorly managed and poorly monitored fisheries. Here, we document conservation through fisheries management success for 11 coastal sharks in US waters by comparing population trends through a Bayesian state-space model before and after the implementation of the 1993 Fisheries Management Plan for Sharks. We took advantage of the spatial and temporal gradients in fishing exposure and fisheries management in the Western Atlantic to analyze the effect on the Red List status of all 26 wide-ranging coastal sharks and rays. We show that extinction risk was greater where fishing pressure was higher, but this was offset by the strength of management engagement (indicated by strength of National and Regional Plan of Action for sharks and rays). The regional Red List Index (which tracks changes in extinction risk through time) declined in all regions until the 1980s but then improved in the North and Central Atlantic such that the average extinction risk is currently half that in the Southwest. Many sharks and rays are wide ranging, and successful fisheries management in one country can be undone by poorly regulated or unregulated fishing elsewhere. Our study underscores that well-enforced, science-based management of carefully monitored fisheries can achieve conservation success, even for slow-growing species

    Atmospheric abundance and global emissions of perfluorocarbons CF4, C2F6 and C3F8 since 1800 inferred from ice core, firn, air archive and in situ measurements

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    Perfluorocarbons (PFCs) are very potent and long-lived greenhouse gases in the atmosphere, released predominantly during aluminium production and semiconductor manufacture. They have been targeted for emission controls under the United Nations Framework Convention on Climate Change. Here we present the first continuous records of the atmospheric abundance of CF4 (PFC-14), C2F6 (PFC-116) and C3F8 (PFC-218) from 1800 to 2014. The records are derived from high-precision measurements of PFCs in air extracted from polar firn or ice at six sites (DE08, DE08-2, DSSW20K, EDML, NEEM and South Pole) and air archive tanks and atmospheric air sampled from both hemispheres. We take account of the age characteristics of the firn and ice core air samples and demonstrate excellent consistency between the ice core, firn and atmospheric measurements. We present an inversion for global emissions from 1900 to 2014. We also formulate the inversion to directly infer emission factors for PFC emissions due to aluminium production prior to the 1980s. We show that 19th century atmospheric levels, before significant anthropogenic influence, were stable at 34.1 ± 0.3 ppt for CF4 and below detection limits of 0.002 and 0.01 ppt for C2F6 and C3F8, respectively. We find a significant peak in CF4 and C2F6 emissions around 1940, most likely due to the high demand for aluminium during World War II, for example for construction of aircraft, but these emissions were nevertheless much lower than in recent years. The PFC emission factors for aluminium production in the early 20th century were significantly higher than today but have decreased since then due to improvements and better control of the smelting process. Mitigation efforts have led to decreases in emissions from peaks in 1980 (CF4) or early-to-mid-2000s (C2F6 and C3F8) despite the continued increase in global aluminium production; however, these decreases in emissions appear to have recently halted. We see a temporary reduction of around 15 % in CF4 emissions in 2009, presumably associated with the impact of the global financial crisis on aluminium and semiconductor production

    Overfishing Drives Over One-Third of All Sharks and Rays Toward a Global Extinction Crisis

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    The scale and drivers of marine biodiversity loss are being revealed by the International Union for Conservation of Nature (IUCN) Red List assessment process. We present the first global reassessment of 1,199 species in Class Chondrichthyes-sharks, rays, and chimeras. The first global assessment (in 2014) concluded that one-quarter (24%) of species were threatened. Now, 391 (32.6%) species are threatened with extinction. When this percentage of threat is applied to Data Deficient species, more than one-third (37.5%) of chondrichthyans are estimated to be threatened, with much of this change resulting from new information. Three species are Critically Endangered (Possibly Extinct), representing possibly the first global marine fish extinctions due to overfishing. Consequently, the chondrichthyan extinction rate is potentially 25 extinctions per million species years, comparable to that of terrestrial vertebrates. Overfishing is the universal threat affecting all 391 threatened species and is the sole threat for 67.3% of species and interacts with three other threats for the remaining third: loss and degradation of habitat (31.2% of threatened species), climate change (10.2%), and pollution (6.9%). Species are disproportionately threatened in tropical and subtropical coastal waters. Science-based limits on fishing, effective marine protected areas, and approaches that reduce or eliminate fishing mortality are urgently needed to minimize mortality of threatened species and ensure sustainable catch and trade of others. Immediate action is essential to prevent further extinctions and protect the potential for food security and ecosystem functions provided by this iconic lineage of predators

    Acute Cardiovascular and Metabolic Responses to Three Modes of Treadmill Exercise in Older Adults with Parkinson’s Disease

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    Parkinson’s disease (PD) is a neurodegenerative condition characterized by muscle tremors, rigidity and dyskinesis leading to balance and gait abnormalities that could alter physiologic responses during exercise. Locomotion on an aquatic treadmill (ATM) or anti-gravity treadmill (AGTM) may be a safe alternative to exercise on a traditional land treadmill (LTM) in those with PD. PUPROSE: To determine the acute cardiovascular and metabolic responses to three different modes of treadmill exercise in older adults diagnosed with Parkinson’s disease. METHODS: Eight adults diagnosed with PD (68 ± 3 years of age) completed one exercise session on an LTM, one session on an ATM, and one session on an AGTM at 50% body weight. Participants walked from 1 to 3 mph in 0.5 mph increments at 0% grade during each exercise session. Heart rate (HR), energy expenditure (EE), systolic blood pressure (SBP), and diastolic blood pressure (DBP) were measured at rest and during steady-state exercise at each speed on each treadmill. Rate of perceived exertion was also measured during steady-state exercise. Rate pressure product (RPP) was calculated. RESULTS: All variables, with the exception of DBP, increased as speed increased across all treadmill modes (p \u3c 0.001). Between treadmill modes across all speeds, EE was statistically different (p = 0.025). There was a significant interaction effect for mode and speed for HR (p \u3c 0.001) and RPP (p = 0.003). At all speeds except 1.5 mph, HR was higher on the LTM versus the AGTM (p \u3c 0.05). CONCLUSION: Exercising on an ATM or an AGTM elicits similar physiologic responses to exercise on an LTM in adults with P

    Changes in Balance, Gait and Motor Skills Following Treadmill Exercise in Adults with Parkinson’s Disease

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    Locomotion on an aquatic treadmill or anti-gravity treadmill may be a safe and effective alternative to exercise on a traditional land treadmill in those with Parkinson’s disease as the removal of body weight in these environments may allow the participant to exercise with less concern of falling at higher speeds before reaching volitional fatigue. PURPOSE: To determine the training effects of three different treadmill modalities on dynamic balance, gait, and fine motor control in older adults diagnosed with Parkinson’s disease. METHODS: Ten adults diagnosed with Parkinson’s disease (70 ± 5 years of age) completed 8 exercise sessions (4 weeks, 2x/week) each separately on a land treadmill, aquatic treadmill, and anti-gravity treadmill at 50% body weight. Two weeks separated each intervention and the order was randomized. A 4-week control period occurred at the start of the study in which no treadmill exercise was performed. Each exercise session included a 2-minute warm-up and 30 minutes at a moderate intensity. Before and after each intervention, balance, gait and fine motor control were measured. Dynamic balance and gait were assessed using a Timed-Up-and-Go test and Performance Oriented Mobility Assessment (POMA). Fine motor control was assessed with the Purdue Pegboard Test. RESULTS: The gait assessment of the POMA was significant across all time points (p = 0.028). All other variables were statistically similar (p \u3e 0.05) across all time points. CONCLUSION: Exercising on a traditional land treadmill, aquatic treadmill, or anti-gravity treadmill for 60 min/week for 4 weeks at a moderate intensity did not alter balance, gait or fine motor control in adults with Parkinson’s disease

    JWST reveals a possible z∼11z \sim 11 galaxy merger in triply-lensed MACS0647−-JD

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    MACS0647−-JD is a triply-lensed z∼11z\sim11 galaxy originally discovered with the Hubble Space Telescope. Here we report new JWST imaging, which clearly resolves MACS0647−-JD as having two components that are either merging galaxies or stellar complexes within a single galaxy. Both are very small, with stellar masses ∼108 M⊙\sim10^8\,M_\odot and radii r<100 pcr<100\,\rm pc. The brighter larger component "A" is intrinsically very blue (β∼−2.6\beta\sim-2.6), likely due to very recent star formation and no dust, and is spatially extended with an effective radius ∼70 pc\sim70\,\rm pc. The smaller component "B" appears redder (β∼−2\beta\sim-2), likely because it is older (100−200 Myr100-200\,\rm Myr) with mild dust extinction (AV∼0.1 magA_V\sim0.1\,\rm mag), and a smaller radius ∼20 pc\sim20\,\rm pc. We identify galaxies with similar colors in a high-redshift simulation, finding their star formation histories to be out of phase. With an estimated stellar mass ratio of roughly 2:1 and physical projected separation ∼400 pc\sim400\,\rm pc, we may be witnessing a galaxy merger 400 million years after the Big Bang. We also identify a candidate companion galaxy C ∼3 kpc\sim3\,{\rm kpc} away, likely destined to merge with galaxies A and B. The combined light from galaxies A+B is magnified by factors of ∼\sim8, 5, and 2 in three lensed images JD1, 2, and 3 with F356W fluxes ∼322\sim322, 203203, 86 nJy86\,\rm nJy (AB mag 25.1, 25.6, 26.6). MACS0647−-JD is significantly brighter than other galaxies recently discovered at similar redshifts with JWST. Without magnification, it would have AB mag 27.3 (MUV=−20.4M_{UV}=-20.4). With a high confidence level, we obtain a photometric redshift of z=10.6±0.3z=10.6\pm0.3 based on photometry measured in 6 NIRCam filters spanning 1−5μm1-5\rm\mu m, out to 4300 A˚4300\,\r{A} rest-frame. JWST NIRSpec observations planned for January 2023 will deliver a spectroscopic redshift and a more detailed study of the physical properties of MACS0647−-JD.Comment: 27 pages, 14 figures, submitted to Natur

    Bullying escolar: um fenômeno multifacetado

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    School bullying can involve children in different ways, making them play different roles, among them, victims, bullies and bully-victims. The aim of this study was to describe how bullying occurs in high social vulnerability schools of Florianópolis metropolitan area and the roles played by students in this phenomenon. Overall, 409 children and adolescents from the 3rd to 5th grades and of two public elementary schools aged 8-16 years (X = 11.14) participated in this study. As a tool, the Olweus Questionnaire adapted to the Brazilian population was used. For data analysis, descriptive statistics and inferential statistics were applied by the Mann Whitney and Kruskal Wallis tests. As for results, 29.8% of boys and 40.5% of girls reported being victims; 32.3% of boys and 24.6% of girls reported being bullies. Victims were the most willing to help a colleague who is suffering from bullying (X = 1.54; p> 0.001), even if they do not know the victims (X = 1.57; p> 0.004). Bullies are differentiated from the group that does not participate (X = 1.73) and the group of victims (X = 2.34), being those who felt less alone (x = 1.47; p> 0.001). It was concluded that the information obtained in this study is indispensable in the search for alternatives to reduce school bullying. The strengthening of relations between school and students and a better preparation of teachers and school staff are extremely necessary to try to minimize the effects of risk factors to which these children are exposed and consequently violence at school.O bullying escolar pode envolver crianças de diferentes maneiras, fazendo com que essas assumam papéis diferenciados. Dentre estes, têm-se vítimas, agressores e vítimas-agressoras. O objetivo deste estudo foi descrever como ocorre o bullying em escolas de alta vulnerabilidade social da Grande Florianópolis e os papéis assumidos pelos alunos nesse fenômeno. Quanto ao método, participaram 409 crianças e adolescentes do terceiro ao quinto ano e da quarta à sexta série do ensino fundamental, de duas escolas públicas municipais, com idades entre 8 e 16 anos (X=11,14). Como instrumento, utilizou-se o Questionário de Olweus adaptado à população brasileira. Para a análise dos dados, empregaram-se a estatística descritiva e estatística inferencial por meio dos testes Mann Whitney e Kruskal Wallis. Quanto aos resultados, 29,8% dos meninos e 40,5% das meninas relataram terem sido vítimas; já 32,3% dos meninos e 24,6% das meninas relataram terem sido agressores. As vítimas foram as que se mostraram mais dispostas a ajudar como podem um colega que esteja sofrendo agressão (X=1,54; p>0,001), mesmo que não o conheçam (X=1,57; p>0,004). Em contrapartida, os agressores se diferenciaram do grupo que não participa (X=1,73) e do grupo das vítimas (X=2,34), sendo aqueles que menos se sentiram sozinhos (X=1,47; p>0,001). Concluiu-se que as informações obtidas neste estudo são indispensáveis na busca de alternativas para redução do bullying escolar. O fortalecimento das relações entre escola e alunos, e um maior preparo dos professores e funcionários são extremamente necessários para tentar minimizar os efeitos dos fatores de risco a que essas crianças estão expostas e consequentemente a violência na escola.CAPES - Proc. nº 0815/14-4CIEC - Centro de Investigação em Estudos da Criança, IE, UMinho (UI 317 da FCT)Projeto Estratégico da FCT: UID/CED/00317/201

    Patterns of Spatial Variation of Assemblages Associated with Intertidal Rocky Shores: A Global Perspective

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    Assemblages associated with intertidal rocky shores were examined for large scale distribution patterns with specific emphasis on identifying latitudinal trends of species richness and taxonomic distinctiveness. Seventy-two sites distributed around the globe were evaluated following the standardized sampling protocol of the Census of Marine Life NaGISA project (www.nagisa.coml.org). There were no clear patterns of standardized estimators of species richness along latitudinal gradients or among Large Marine Ecosystems (LMEs); however, a strong latitudinal gradient in taxonomic composition (i.e., proportion of different taxonomic groups in a given sample) was observed. Environmental variables related to natural influences were strongly related to the distribution patterns of the assemblages on the LME scale, particularly photoperiod, sea surface temperature (SST) and rainfall. In contrast, no environmental variables directly associated with human influences (with the exception of the inorganic pollution index) were related to assemblage patterns among LMEs. Correlations of the natural assemblages with either latitudinal gradients or environmental variables were equally strong suggesting that neither neutral models nor models based solely on environmental variables sufficiently explain spatial variation of these assemblages at a global scale. Despite the data shortcomings in this study (e.g., unbalanced sample distribution), we show the importance of generating biological global databases for the use in large-scale diversity comparisons of rocky intertidal assemblages to stimulate continued sampling and analyses
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