336 research outputs found

    Local Star formation triggered by SN shocks in magnetized diffuse neutral clouds

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    In this work, considering the impact of a SNR with a neutral magnetized cloud we derived analytically a set of conditions which are favorable for driving gravitational instability in the cloud and thus star formation. We have built diagrams of the SNR radius, versus the cloud density, that constrain a domain in the parameter space where star formation is allowed. The diagrams are also tested with fully 3-D MHD simulations involving a SNR and a self-gravitating cloud and we find that the numerical analysis is consistent with the results predicted by the diagrams. While the inclusion of a homogeneous magnetic field approximately perpendicular to the impact velocity of the SNR with an intensity ~1 mu muG results only a small shrinking of the star formation triggering zone in the diagrams, a larger magnetic field (~10 mu muG) causes a significant shrinking, as expected. Applications of the diagrams to a few regions of our own galaxy have revealed that star formation in those sites could have been triggered by shock waves from SNRs. Finally, we have evaluated the effective star formation efficiency for this sort of interaction and found that it is smaller than the observed values in our own Galaxy (sfe ~0.01-0.3). This result is consistent with previous work in the literature and also suggests that the mechanism presently investigated, though very powerful to drive structure formation, supersonic turbulence and eventually, local star formation, does not seem to be sufficient to drive global star formation in normal star forming galaxies, not even when the magnetic field in the neutral clouds is neglected. (abridged)Comment: 19 pages, 13 figures, accepted for pubblication in MNRA

    Simulating shifts in taxonomic and functional β-diversity of ray-finned fishes : probing the Mariana disaster

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    ITS was supported by stipends provided by CAPES (Coordination for the Improvement of Higher Education Personnel, #88881.129579/2016-01) and CNPq (National Council for Scientific and Technological Development). SFG has been supported by CNPq (#303180/2016-1 and #402469/2016-0), CAPES/FAPITEC (#88881.157961/2017-01; #88881.157451/2017-01) and Instituto Serrapilheira (G-1709-18372). AEM and FM acknowledge funding from ERC (ERCAdG BioTIME 250189 and ERCPoC BioCHANGE 727440). ITS, PAM and SFG are members of the National Science and Technology Institute of Ecology, Evolution, and Conservation of Biodiversity – INCT EECBio (CNPq/FAPEG).Environmental catastrophes may precipitate local species extinctions, hence altering community composition (i.e., β-diversity) at the regional scale. Assessments of the impacts of such disturbance may be hindered by the availability of sufficiently high-quality before/after data. However, simulations can provide key insights into the nature of the biodiversity change involved, even when data are limited. Using a simulation approach, we asked how disturbances might have affected regional patterns of β-diversity, following the ‘Mariana disaster’ at the Bento Rodrigues dam in the Doce River Basin. To do this we evaluated the possible consequences of different levels of local species extinctions on the regional taxonomic and functional β-diversity. Our analysis drew on information from all six neighbouring river basins and contrasted the β-diversity prior to the disaster with four hypothetical scenarios of species removal from the Doce Basin of 25, 50, 75, and 100%. We found that local species extinction increases regional taxonomic β-diversity as a result of a higher contribution of nestedness (from 13% to 19%). Functional β-diversity also increases, but with an even greater contribution of nestedness (67–81%). Our results suggest that, if the disaster prompted any extinction, this was likely to lead to altered patterns of regional β-diversity by making assemblages taxonomically more distinct but functionally more similar. These changes result from the loss of unique species and, in particular, their functional traits. Our work highlights the utility of simulation approaches in environmental impact assessment and conservation management in data-poor circumstances.Publisher PDFPeer reviewe

    Mortalidad de aves marinas producida por luces artificiales terrestres

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    Artificial lights at night cause high mortality of seabirds, one of the most endangered groups of birds globally. Fledglings of burrow-nesting seabirds, and to a lesser extent adults, are attracted to and then grounded (i.e., forced to land) by lights when they fly at night. We reviewed the current state of knowledge of seabird attraction to light to identify information gaps and propose measures to address the problem. Although species in families such as Alcidae and Anatidae can be grounded by artificial light, the most affected seabirds are petrels and shearwaters (Procellariiformes). At least 56 species of Procellariiformes, more than one-third of them (24) threatened, are subject to grounding by lights. Seabirds grounded by lights have been found worldwide, mainly on oceanic islands but also at some continental locations. Petrel breeding grounds confined to formerly uninhabited islands are particularly at risk from light pollution due to tourism and urban sprawl. Where it is impractical to ban external lights, rescue programs of grounded birds offer the most immediate and employed mitigation to reduce the rate of light-induced mortality and save thousands of birds every year. These programs also provide useful information for seabird management. However, these data are typically fragmentary, biased, and uncertain and can lead to inaccurate impact estimates and poor understanding of the phenomenon of seabird attraction to lights. We believe the most urgently needed actions to mitigate and understand light-induced mortality of seabirds are estimation of mortality and effects on populations; determination of threshold light levels and safe distances from light sources; documentation of the fate of rescued birds; improvement of rescue campaigns, particularly in terms of increasing recovery rates and level of care; and research on seabird-friendly lights to reduce attraction.RESUMEN: Las luces artificiales nocturnas causan una mortalidad alta de aves marinas, uno de los grupos de aves en mayor peligro de extinción a nivel mundial. Los polluelos de aves marinas que anidan en madrigueras, y en menor medida los adultos, son atraídos y forzados a aterrizar por las luces cuando vuelan de noche. Revisamos el estado actual del conocimiento sobre la atracción de las aves marinas por la luz para identificar vacíos de información y proponer medidas para resolver el problema. Aunque las especies de familias como Alcidae y Anatidae pueden ser forzadas a aterrizar por la luz artificial, las aves marinas más afectadas son los petreles y las pardelas (Procellariiformes). Por lo menos 56 especies de Procellariiformes, más de un tercio (24) de ellas amenazadas, son propensas al aterrizaje atraídas por las luces. Las aves marinas forzadas a aterrizar han sido halladas en todo el mundo, principalmente en islas oceánicas, pero también en algunas localidades continentales. Los sitios de anidación de los petreles confinados anteriormente a islas deshabitadas están particularmente en riesgo de sufrir contaminación lumínica debido al turismo y al crecimiento urbano. En donde no es práctico prohibir las luces externas, los programas de rescate de las aves accidentadas ofrecen la mitigación más inmediata y empleada para reducir la tasa de mortalidad inducida por la luz y salvar a miles de aves cada año. Estos programas también proporcionan información útil para el manejo de aves marinas. Sin embargo, estos datos están típicamente fragmentados, sesgados y son inciertos, y pueden llevar a estimaciones inexactas del impacto y a un entendimiento pobre del fenómeno de la atracción de las aves marinas por la luz. Creemos que las acciones necesarias de mayor urgencia para mitigar y entender la mortalidad de aves marinas producida por la luz son: la estimación de la mortalidad y los efectos sobre la población; la determinación de umbrales de niveles de luz y de distancias seguras a las fuentes de luz; el estudio del destino de las aves rescatadas; la mejora de las campañas de rescate, particularmente en términos de incrementar las tasas de recogida y el nivel de cuidado; y la investigación sobre las características de la luz para reducir la atracción de las aves marinas.This research was supported by a Marie Curie Intra European Fellowship within the 7th European Community Framework Programme (Project ID: 330655 FP7-PEOPLE-2012-IOF)info:eu-repo/semantics/publishedVersio

    Diseases of the nervous system of cattle in Mato Grosso do Sul, Brazil : 1082 cases

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    Foi realizado um estudo retrospectivo de janeiro de 2008 a dezembro de 2012 com base nos laudos de necropsia do Laboratório de Anatomia Patológica (LAP) da Faculdade de Medicina Veterinária e Zootecnia (FAMEZ), Universidade Federal de Mato Grosso do Sul (UFMS), com o intuito de descrever quais as doenças que afetam o sistema nervoso de bovinos que ocorrem no Mato Grosso do Sul. Os casos consistiam de acompanhados por técnicos do LAP e encaminhados por médicos veterinários que atuam no campo (autônomos ou do serviço veterinário oficial). De 1082 materiais analisados, 588 apresentavam histórico de sinais clínicos neurológicos. Destes, 341 (53,75%) tiveram diagnóstico correspondente a doenças neurológicas e 247 (46,25%) tiveram diagnóstico inconclusivos. As fichas clínico epidemiológicas foram revisadas para determinar dados referentes a epidemiologia, aos sinais clínicos e às alterações macroscópicas e microscópicas. O botulismo (16,67%), a raiva (15,92%), a polioencefalomalacia (8,05%) e a encefalite por herpesvirus bovino (4,31%) foram as enfermidade de maior frequência. Outras doenças como meningoencefalite não supurativa (2,62%), meningoencefalite supurativa (1,50%), abscessos cerebrais e osteomielite por compressão medular (1,31%), tétano (1,12%), hipotermia (0,94%), babesiose cerebral (0,75%), febre catarral maligna (0,37%) e lesões sugestivas de intoxicação por oxalato (0,19%) foram ocasionalmente diagnosticadas. Em nenhum dos casos foram observadas lesões que pudessem sugerir encefalopatia espongiforme bovina.The aim of this study was to describe the types of diseases that affect the nervous system of cattle from the State of Mato Grosso do Sul, Brazil. A retrospective study from January 2008 to December 2012 was perfomed, based on reports of cattle autopsies autopsy carried out by the Laboratório de Anatomia Patológica (LAP), Faculdade de Medicina Veterinária e Zootecnia (FAMEZ), Universidade Federal de Mato Grosso do Sul (UFMS). The material came from cases attended and forwarded to LAP by practicing veterinarians autonomous and from the official veterinary service. From 1028 cases studied, 588 presented a history of neurological clinical signs, 341 (53.75%) of which were diagnosed as affected bytrue neurological disease, and 247 (46.25%) had inconclusive diagnosis. The clinical records were reviewed to determine epidemiology, clinical signs, and gross and histopathological features. The most frequent diseases were botulism (16.67%), rabies (15.92%), polioencephalomalacia (8.05%), and herpesviral meningoencephalitis (4.31%). Other conditions were diagnosed occasionally, and included non suppurative meningoencephalitis (2.62%), suppurative meningoencephalitis (1.50%), brain abscesses and osteomyelitis caused by spinal cord compression (1.31%), tetanus (1.12%), hypothermia (0.94%), cerebral babesiosis (0.75%), malignant catarrhal fever (0.37%), and cases suggestive of oxalate poisoning (0.19%). No cases with lesions that may suggest of bovine spongiform encephalopathy were observed

    Autoimmune and autoinflammatory mechanisms in uveitis

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    The eye, as currently viewed, is neither immunologically ignorant nor sequestered from the systemic environment. The eye utilises distinct immunoregulatory mechanisms to preserve tissue and cellular function in the face of immune-mediated insult; clinically, inflammation following such an insult is termed uveitis. The intra-ocular inflammation in uveitis may be clinically obvious as a result of infection (e.g. toxoplasma, herpes), but in the main infection, if any, remains covert. We now recognise that healthy tissues including the retina have regulatory mechanisms imparted by control of myeloid cells through receptors (e.g. CD200R) and soluble inhibitory factors (e.g. alpha-MSH), regulation of the blood retinal barrier, and active immune surveillance. Once homoeostasis has been disrupted and inflammation ensues, the mechanisms to regulate inflammation, including T cell apoptosis, generation of Treg cells, and myeloid cell suppression in situ, are less successful. Why inflammation becomes persistent remains unknown, but extrapolating from animal models, possibilities include differential trafficking of T cells from the retina, residency of CD8(+) T cells, and alterations of myeloid cell phenotype and function. Translating lessons learned from animal models to humans has been helped by system biology approaches and informatics, which suggest that diseased animals and people share similar changes in T cell phenotypes and monocyte function to date. Together the data infer a possible cryptic infectious drive in uveitis that unlocks and drives persistent autoimmune responses, or promotes further innate immune responses. Thus there may be many mechanisms in common with those observed in autoinflammatory disorders

    Potent Innate Immune Response to Pathogenic Leptospira in Human Whole Blood

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    Background: Leptospirosis is caused by pathogenic spirochetes of the genus Leptospira. The bacteria enter the human body via abraded skin or mucous membranes and may disseminate throughout. In general the clinical picture is mild but some patients develop rapidly progressive, severe disease with a high case fatality rate. Not much is known about the innate immune response to leptospires during haematogenous dissemination. Previous work showed that a human THP-1 cell line recognized heat-killed leptospires and leptospiral LPS through TLR2 instead of TLR4. The LPS of virulent leptospires displayed a lower potency to trigger TNF production by THP-1 cells compared to LPS of non-virulent leptospires. Methodology/Principal Findings: We investigated the host response and killing of virulent and non-virulent Leptospira of different serovars by human THP-1 cells, human PBMC's and human whole blood. Virulence of each leptospiral strain was tested in a well accepted standard guinea pig model. Virulent leptospires displayed complement resistance in human serum and whole blood while in-vitro attenuated non-virulent leptospires were rapidly killed in a complement dependent manner. In vitro stimulation of THP-1 and PBMC's with heat-killed and living leptospires showed differential serovar and cell type dependence of cytokine induction. However, at low, physiological, leptospiral dose, living virulent complement resistant strains were consistently more potent in whole blood stimulations than the corresponding non-virulent complement sensitive strains. At higher dose living virulent and non-virulent leptospires were equipotent in whole blood. Inhibition of different TLRs indicated that both TLR2 and TLR4 as well as TLR5 play a role in the whole blood cytokine response to living leptospires. Conclusions/Significance: Thus, in a minimally altered system as human whole blood, highly virulent Leptospira are potent inducers of the cytokine response

    Cardiovascular diseases and air pollution in Novi Sad, Serbia

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    Objectives: A large body of evidence has documented that air pollutants have adverse effect on human health as well as on the environment. The aim of this study was to determine whether there was an association between outdoor concentrations of sulfur dioxide (SO2) and nitrogen dioxide (NO2) and a daily number of hospital admissions due to cardiovascular diseases (CVD) in Novi Sad, Serbia among patients aged above 18. Material and Methods: The investigation was carried out during over a 3-year period (from January 1, 2007 to December 31, 2009) in the area of Novi Sad. The number (N = 10 469) of daily CVD (ICD-10: I00-I99) hospital admissions was collected according to patients' addresses. Daily mean levels of NO2 and SO2, measured in the ambient air of Novi Sad via a network of fixed samplers, have been used to put forward outdoor air pollution. Associations between air pollutants and hospital admissions were firstly analyzed by the use of the linear regression in a single polluted model, and then trough a single and multi-polluted adjusted generalized linear Poisson model. Results: The single polluted model (without confounding factors) indicated that there was a linear increase in the number of hospital admissions due to CVD in relation to the linear increase in concentrations of SO2 (p = 0.015; 95% confidence interval (95% CI): 0.144-1.329, R2 = 0.005) and NO2 (p = 0.007; 95% CI: 0.214-1.361, R2 = 0.007). However, the single and multi-polluted adjusted models revealed that only NO2 was associated with the CVD (p = 0.016, relative risk (RR) = 1.049, 95% CI: 1.009-1.091 and p = 0.022, RR = 1.047, 95% CI: 1.007-1.089, respectively). Conclusions: This study shows a significant positive association between hospital admissions due to CVD and outdoor NO2 concentrations in the area of Novi Sad, Serbia

    A process model of the formation of spatial presence experiences

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    In order to bridge interdisciplinary differences in Presence research and to establish connections between Presence and “older” concepts of psychology and communication, a theoretical model of the formation of Spatial Presence is proposed. It is applicable to the exposure to different media and intended to unify the existing efforts to develop a theory of Presence. The model includes assumptions about attention allocation, mental models, and involvement, and considers the role of media factors and user characteristics as well, thus incorporating much previous work. It is argued that a commonly accepted model of Spatial Presence is the only solution to secure further progress within the international, interdisciplinary and multiple-paradigm community of Presence research

    Design, Construction and Installation of the ATLAS Hadronic Barrel Scintillator-Tile Calorimeter

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    The scintillator tile hadronic calorimeter is a sampling calorimeter using steel as the absorber structure and scintillator as the active medium. The scintillator is located in "pockets" in the steel structure and the wavelength-shifting fibers are contained in channels running radially within the absorber to photomultiplier tubes which are located in the outer support girders of the calorimeter structure. In addition, to its role as a detector for high energy particles, the tile calorimeter provides the direct support of the liquid argon electromagnetic calorimeter in the barrel region, and the liquid argon electromagnetic and hadronic calorimeters in the endcap region. Through these, it indirectly supports the inner tracking system and beam pipe. The steel absorber, and in particular the support girders, provide the flux return for the solenoidal field from the central solenoid. Finally, the end surfaces of the barrel calorimeter are used to mount services, power supplies and readout crates for the inner tracking systems and the liquid argon barrel electromagnetic calorimeter
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