1,969 research outputs found

    Magnetic Reconnection, Cosmic Ray Acceleration, and Gamma-Ray emission around Black Holes and Relativistic Jets

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    Particle acceleration by magnetic reconnection is now recognized as an important process in magnetically dominated regions of galactic and extragalactic black hole sources. This process helps to solve current puzzles specially related to the origin of the very high energy flare emission in these sources. In this review, we discuss this acceleration mechanism and show recent analytical studies and multidimensional numerical SRMHD and GRMHD (special and general relativistic magnetohydrodynamical) simulations with the injection of test particles, which help us to understand this process both in relativistic jets and coronal regions of these sources. The very high energy and neutrino emission resulting from the accelerated particles by reconnection is also discussed.Comment: Invited Review at the International Conference on Black Holes as Cosmic Batteries: UHECRs and Multimessenger Astronomy - BHCB2018, 12-15 September, 2018, Foz du Iguazu, Brasil, in press in Procs. of Science. arXiv admin note: text overlap with arXiv:1608.0317

    Adaptive introgression underlies polymorphic seasonal camouflage in snowshoe hares

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    Snowshoe hares (Lepus americanus) maintain seasonal camouflage by molting to a white winter coat, but some hares remain brown during the winter in regions with low snow cover. We show that cis-regulatory variation controlling seasonal expression of the Agouti gene underlies this adaptive winter camouflage polymorphism. Genetic variation at Agouti clustered by winter coat color across multiple hare and jackrabbit species, revealing a history of recurrent interspecific gene flow. Brown winter coats in snowshoe hares likely originated from an introgressed black-tailed jackrabbit allele that has swept to high frequency in mild winter environments. These discoveries show that introgression of genetic variants that underlie key ecological traits can seed past and ongoing adaptation to rapidly changing environments. (c) The Authors, Some Rights Reserved

    How the 'plates' of a health system can shift, change and adjust during economic recessions: A qualitative interview study of public and private health providers in Brazil's Sao Paulo and Maranhao states

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    Background: Economic recessions carry an impact on population health and access to care; less is known on how health systems adapt to the conditions brought by a downturn. This particularly matters now that the COVID-19 epidemic is putting health systems under stress. Brazil is one of the world’s most affected countries, and its health system was already experiencing the aftermath of the 2015 recession. Methods: Between 2018 and 2019 we conducted 46 semi-structured interviews with health practitioners, managers and policy-makers to explore the impact of the 2015 recession on public and private providers in prosperous (São Paulo) and impoverished (Maranhão) states in Brazil. Thematic analysis was employed to identify drivers and consequences of system adaptation and coping strategies. Nvivo software was used to aid data collection and analysis. We followed the Standards for Reporting Qualitative Research to provide an account of the findings. Results: We found the concept of ‘health sector crisis’ to be politically charged among healthcare providers in São Paulo and Maranhão. Contrary to expectations, the public sector was reported to have found ways to compensate for diminishing federal funding, having outsourced services and adopted flexible–if insecure–working arrangements. Following a drop in employment and health plans, private health insurance companies have streamlined their offer, at times at the expenses of coverage. Low-cost walk-in clinics were hit hard by the recession, but were also credited for having moved to cater for higher-income customers in Maranhão. Conclusions: The ‘plates’ of a health system may shift and adjust in unexpected ways in response to recessions, and some of these changes might outlast the crisis. As low-income countries enter post-COVID economic recessions, it will be important to monitor the adjustments taking place in health systems, to ensure that past gains in access to care and job security are not eroded

    Cholesteryl hemiazelate causes lysosome dysfunction impacting vascular smooth muscle cell homeostasis

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    In atherosclerotic lesions, vascular smooth muscle cells (VSMCs) represent half of the foam cell population, which is characterized by an aberrant accumulation of undigested lipids within lysosomes. Loss of lysosome function impacts VSMC homeostasis and disease progression. Understanding the molecular mechanisms underlying lysosome dysfunction in these cells is, therefore, crucial. We identify cholesteryl hemiazelate (ChA), a stable oxidation end-product of cholesteryl-polyunsaturated fatty acid esters, as an inducer of lysosome malfunction in VSMCs. ChA-treated VSMCs acquire a foam-cell-like phenotype, characterized by enlarged lysosomes full of ChA and neutral lipids. The lysosomes are perinuclear and exhibit degradative capacity and cargo exit defects. Lysosome luminal pH is also altered. Even though the transcriptional response machinery and autophagy are not activated by ChA, the addition of recombinant lysosomal acid lipase (LAL) is able to rescue lysosome dysfunction. ChA significantly affects VSMC proliferation and migration, impacting atherosclerosis. In summary, this work shows that ChA is sufficient to induce lysosomal dysfunction in VSMCs, that, in ChA-treated VSMCs, neither lysosome biogenesis nor autophagy are triggered, and, finally, that recombinant LAL can be a therapeutic approach for lysosomal dysfunction

    Medicinal animals used in ethnoveterinary practices of the 'Cariri Paraibano', NE Brazil

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    <p>Abstract</p> <p>Background</p> <p>Zootherapy is important in various socio-cultural environments, and innumerous examples of the use of animal derived remedies can currently be found in many urban, semi-urban and more remote localities in all parts of the world, particularly in developing countries. However, although a number of ethnobiological inventories concerning the use of medicinal animals in human health care have been compiled in Brazil in recent years, zootherapeutic practices in ethnoveterinary medicine (EVM) are poorly described and neglected in favor of human ethnomedicine. In this sense, the purpose of this study was to describe the local zootherapeutic practices in ethnoveterinary medicine of semi-arid of NE Brazil (Caatinga biome) and to contribute to future research about the validation of the effects and side effects of these animal products</p> <p>Methods</p> <p>The information obtained through semi-structured interviews was complemented by free interviews and informal conversations. A total of 67 people were interviewed (53 men and 14 women) about the use and commercialization of medicinal animals. To determine the relative importance of each local known species, their use-values (UV) were calculated. Diversity of species utilized was compared, between localities, using rarefaction curves and diversity estimate (Chao2)</p> <p>Results and Conclusions</p> <p>A total of 44 animal species (37 vertebrates and 7 invertebrates), distributed among 6 taxonomic categories were found to be used to treat 30 different ailments in livestock and pets. The results of our surveys revealed a rich traditional knowledge of local residents about the use of animals in traditional veterinary medicine. Although it is gradually being discontinued, the perceived efficacy, economic and geographic accessibility were main reasons for popularity of zootherapy in studied areas.</p

    Detection and Antimicrobial Resistance Profile of Enteropathogenic (EPEC) and Shigatoxigenic Escherichia coli (STEC) in Conventional and Organic Broiler Chickens

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    ABSTRACT Enteropatogenic Escherichia coli (EPEC) and shigatoxigenic E. coli (STEC), are generally poultry and poultry product isolate and can cause serious human infections. Many strains may become resistant to various antimicrobials, which can hinder the treatment of bacterial diseases. Organic farming seeks to avoid the selection and frequency of antimicrobial-resistant bacteria. This study aims to verify the resistance of EPEC and STEC from organic and conventional (industrial) broiler isolates to antimicrobials. All isolates were submitted to disk diffusion test with tetracycline, gentamicin, enrofloxacin, ceftriaxone and amoxicillin + clavulanate (TET, GEN, ENO, CTX, AMC) and PCR to detect specific virulence genes for EPEC and STEC. A total of 297 E. coli strains were isolated, 213 from conventional. In organic broiler, 84 strains were isolated. The strains from the conventional broiler isolates were resistant to five antimicrobials tested: TET 48.82% (104/213), ENO 28.17% (60/213), CTX 15.49% (33/213), GEN 14.55% (31/213), and AMC 7.04% (15/213), and 9.86% (21/213) were considered multidrug-resistant. Organic chicken strains were resistant to four of the antimicrobials tested: TET 35.7% (30/84), ENO 9.5% (8/84), CTX 2.4% (2/84), GEN 4.8% (4/84). Of the strains from the organic broiler chicken isolates, only 1.2% (1/84) was considered multidrug-resistant. No EPEC and STEC were found in the organic chicken samples. The multidrug resistance was characterized in 9.52% (2/21) of the EPEC and 4.76% (1/21) of the STEC. The study demonstrated the absence of EPEC and STEC strains in organic broilers and carcasses and a lower frequency of multiresistant strains compared to conventional breeding
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