396 research outputs found

    BASS. XLII. The Relation between the Covering Factor of Dusty Gas and the Eddington Ratio in Nearby Active Galactic Nuclei

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    Accreting supermassive black holes (SMBHs) located at the centers of galaxies are typically surrounded by large quantities of gas and dust. The structure and evolution of this circumnuclear material can be studied at different wavelengths, from the submillimeter to the X-ray. Recent X-ray studies have shown that the covering factor of the obscuring material tends to decrease with increasing Eddington ratio, likely due to radiative feedback on dusty gas. Here we study a sample of 549 nearby (z less than or similar to 0.1) hard X-ray (14-195 keV) selected nonblazar active galactic nuclei (AGN) and use the ratio between the AGN infrared and bolometric luminosity as a proxy of the covering factor. We find that, in agreement with what has been found by X-ray studies of the same sample, the covering factor decreases with increasing Eddington ratio. We also confirm previous findings that showed that obscured AGN typically have larger covering factors than unobscured sources. Finally, we find that the median covering factors of AGN located in different regions of the column density-Eddington ratio diagram are in good agreement with what would be expected from a radiation-regulated growth of SMBHs

    Cons√≥rcio couve-coentro em cultivo org√Ęnico e sua influ√™ncia nas popula√ß√Ķes de joaninhas.

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    O cons√≥rcio de culturas √© comumente praticado na produ√ß√£o de hortali√ßas devido a diversos benef√≠cios econ√īmicos. Em alguns casos, podem reduzir infesta√ß√Ķes de pragas por favorecer a conserva√ß√£o dos inimigos naturais nos agroecossistemas. Avaliou-se a viabilidade agron√īmica do cons√≥rcio de couve e coentro, sob manejo org√Ęnico, com base em par√Ęmetros fitot√©cnicos, al√©m de sua influ√™ncia sobre popula√ß√Ķes de joaninhas (Coleoptera: Coccinellidae), na compara√ß√£o com os respectivos cultivos solteiros. O coentro, representando a cultura secund√°ria, foi utilizado com a finalidade de fornecer recursos para as joaninhas. O estudo foi realizado em √°rea do Sistema Integrado de Produ√ß√£o Agroecol√≥gica em Serop√©dica-RJ. O experimento consistiu dos cons√≥rcios: 1) couve consorciada com coentro, cujas quatro linhas de plantas foram colhidas na fase vegetativa (cons√≥rcio I), e 2) couve consorciada com coentro, cujas plantas das duas linhas internas (pr√≥ximas √† linha da couve) foram colhidas na fase vegetativa e as duas linhas externas foram cortadas ap√≥s flora√ß√£o (cons√≥rcio II). Em ambos cons√≥rcios foram avaliados os par√Ęmetros fitot√©cnicos da couve e do coentro na fase vegetativa (padr√£o comercial), enquanto que no cons√≥rcio II, tamb√©m se avaliou as popula√ß√Ķes de joaninhas, por meio de coletas semanais de adultos, em compara√ß√£o com a couve em cultivo solteiro. O delineamento experimental foi em blocos ao acaso com quatro repeti√ß√Ķes. O coentro n√£o interferiu na produtividade da couve consorciada e sua introdu√ß√£o contribuiu positivamente para a abund√Ęncia e diversidade de esp√©cies de joaninhas. O √≠ndice de equival√™ncia de √°rea para o cons√≥rcio I, com refer√™ncia aos rendimentos de biomassa a√©rea fresca, foi superior em 92% em rela√ß√£o ao cultivo solteiro. Este resultado demonstra a viabilidade do cons√≥rcio I, no manejo org√Ęnico adotado, para plantios de outono nas condi√ß√Ķes edafoclim√°ticas da Baixada Fluminense

    Localization of the Cochlear Amplifier in Living Sensitive Ears

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    BACKGROUND: To detect soft sounds, the mammalian cochlea increases its sensitivity by amplifying incoming sounds up to one thousand times. Although the cochlear amplifier is thought to be a local cellular process at an area basal to the response peak on the spiral basilar membrane, its location has not been demonstrated experimentally. METHODOLOGY AND PRINCIPAL FINDINGS: Using a sensitive laser interferometer to measure sub-nanometer vibrations at two locations along the basilar membrane in sensitive gerbil cochleae, here we show that the cochlea can boost soft sound-induced vibrations as much as 50 dB/mm at an area proximal to the response peak on the basilar membrane. The observed amplification works maximally at low sound levels and at frequencies immediately below the peak-response frequency of the measured apical location. The amplification decreases more than 65 dB/mm as sound levels increases. CONCLUSIONS AND SIGNIFICANCE: We conclude that the cochlea amplifier resides at a small longitudinal region basal to the response peak in the sensitive cochlea. These data provides critical information for advancing our knowledge on cochlear mechanisms responsible for the remarkable hearing sensitivity, frequency selectivity and dynamic range

    The MCL-1 BH3 helix is an exclusive MCL-1 inhibitor and apoptosis sensitizer

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    available in PMC 2011 February 3.MCL-1 has emerged as a major oncogenic and chemoresistance factor. A screen of stapled peptide helices identified the MCL-1 BH3 domain as selectively inhibiting MCL-1 among the related anti-apoptotic Bcl-2 family members, providing insights into the molecular determinants of binding specificity and a new approach for sensitizing cancer cells to apoptosis.National Institutes of Health (U.S.) (NIH award 5RO1GM084181)National Institutes of Health (U.S.) (NIH grant 5P01CA92625)National Institutes of Health (U.S.) (Ruth L. Kirschstein National Research Service Award 1F31CA144566)Burroughs Wellcome Fund (Career Award

    Recent Advances in Childhood Arterial Ischemic Stroke

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    Although many underlying diseases have been reported in the setting of childhood arterial ischemic stroke, emerging research demonstrates that non-atherosclerotic intracerebral arteriopathies in otherwise healthy children are prevalent. Minor infections may play a role in arteriopathies that have no other apparent underlying cause. Although stroke in childhood differs in many aspects from adult stroke, few systematic studies specific to pediatrics are available to inform stroke management. Treatment trials of pediatric stroke are required to determine the best strategies for acute treatment and secondary stroke prevention. The high cost of pediatric stroke to children, families, and society demands further study of its risk factors, management, and outcomes. This review focuses on the recent findings in childhood arterial ischemic stroke
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