1,010 research outputs found

    Арап элифбесинде нешир этильген къырымтатар грамматикаларнынъ тенъештирме талили

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    Статья посвящена сопоставительному анализу имени существительного и глагола в арабографических грамматиках крымскотатарского языка.Стаття присвячена порівняльному аналізу іменника і дієслова в арабографічних граматиках кримськотатарської мови.The article annotation is devoted to the comparative analysis of the noun and the verb in arabographis grammars of the Crimean Tatar language

    Emergent SU(2) dynamics and perfect quantum many-body scars

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    Motivated by recent experimental observations of coherent many-body revivals in a constrained Rydberg atom chain, we construct a weak quasi-local deformation of the Rydberg blockade Hamiltonian, which makes the revivals virtually perfect. Our analysis suggests the existence of an underlying non-integrable Hamiltonian which supports an emergent SU(2)-spin dynamics within a small subspace of the many-body Hilbert space. We show that such perfect dynamics necessitates the existence of atypical, nonergodic energy eigenstates - quantum many-body scars. Furthermore, using these insights, we construct a toy model that hosts exact quantum many-body scars, providing an intuitive explanation of their origin. Our results offer specific routes to enhancing coherent many-body revivals, and provide a step towards establishing the stability of quantum many-body scars in the thermodynamic limit

    Anti-cytokine therapy in fibrosing alveolitis: where are we now?

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    Idiopathic pulmonary fibrosis (IPF) is a condition that has a poor prognosis, with a median survival of 4-5 years irrespective of treatment. Ziesche et al (N Engl J Med 1999, 341: 1264-1269) describe an open randomised trial of 18 patients with IPF, unresponsive to corticosteroid treatment at high dose. Nine patients were treated with continued corticosteroid and nine with prednisolone plus interferon-γ 1b (IFN-γ). Significant benefits in physiological parameters are reported in the IFN-γ-treated group. An analysis of lung tissue by reverse-transcriptase-mediated polymerase chain reaction showed corresponding decreases in the transcription of transforming growth factor-β1 and connective tissue growth factor. This is the first report of treatment showing efficacy in this disease, albeit in a very preliminary study, but the data should be viewed with caution. This study is discussed in the context of other published studies of treatment for IPF and the scientific rationale on which it was based

    Chronic Obstructive Pulmonary Disease: Effects beyond the Lungs

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    Peter Barnes discusses the growing epidemic of chronic obstructive pulmonary disease (COPD), especially in developing countries and among nonsmokers

    Galaxy evolution: black hole feedback in the luminous quasar PDS 456

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    The evolution of galaxies is connected to the growth of supermassive black holes in their centers. During the quasar phase, a huge luminosity is released as matter falls onto the black hole, and radiation-driven winds can transfer most of this energy back to the host galaxy. Over five different epochs, we detected the signatures of a nearly spherical stream of highly ionized gas in the broadband x-ray spectra of the luminous quasar PDS 456. This persistent wind is expelled at relativistic speeds from the inner accretion disk, and its wide aperture suggests an effective coupling with the ambient gas. The outflow's kinetic power larger than 10(46) ergs per second is enough to provide the feedback required by models of black hole and host galaxy coevolution

    Phylogenetic Codivergence Supports Coevolution of Mimetic Heliconius Butterflies

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    The unpalatable and warning-patterned butterflies _Heliconius erato_ and _Heliconius melpomene_ provide the best studied example of mutualistic Müllerian mimicry, thought – but rarely demonstrated – to promote coevolution. Some of the strongest available evidence for coevolution comes from phylogenetic codivergence, the parallel divergence of ecologically associated lineages. Early evolutionary reconstructions suggested codivergence between mimetic populations of _H. erato_ and _H. melpomene_, and this was initially hailed as the most striking known case of coevolution. However, subsequent molecular phylogenetic analyses found discrepancies in phylogenetic branching patterns and timing (topological and temporal incongruence) that argued against codivergence. We present the first explicit cophylogenetic test of codivergence between mimetic populations of _H. erato_ and _H. melpomene_, and re-examine the timing of these radiations. We find statistically significant topological congruence between multilocus coalescent population phylogenies of _H. erato_ and _H. melpomene_, supporting repeated codivergence of mimetic populations. Divergence time estimates, based on a Bayesian coalescent model, suggest that the evolutionary radiations of _H. erato_ and _H. melpomene_ occurred over the same time period, and are compatible with a series of temporally congruent codivergence events. This evidence supports a history of reciprocal coevolution between Müllerian co-mimics characterised by phylogenetic codivergence and parallel phenotypic change

    All clinically-relevant blood components transmit prion disease following a single blood transfusion: a sheep model of vCJD

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    Variant CJD (vCJD) is an incurable, infectious human disease, likely arising from the consumption of BSE-contaminated meat products. Whilst the epidemic appears to be waning, there is much concern that vCJD infection may be perpetuated in humans by the transfusion of contaminated blood products. Since 2004, several cases of transfusion-associated vCJD transmission have been reported and linked to blood collected from pre-clinically affected donors. Using an animal model in which the disease manifested resembles that of humans affected with vCJD, we examined which blood components used in human medicine are likely to pose the greatest risk of transmitting vCJD via transfusion. We collected two full units of blood from BSE-infected donor animals during the pre-clinical phase of infection. Using methods employed by transfusion services we prepared red cell concentrates, plasma and platelets units (including leucoreduced equivalents). Following transfusion, we showed that all components contain sufficient levels of infectivity to cause disease following only a single transfusion and also that leucoreduction did not prevent disease transmission. These data suggest that all blood components are vectors for prion disease transmission, and highlight the importance of multiple control measures to minimise the risk of human to human transmission of vCJD by blood transfusion

    Dimethyl sulfide production: what is the contribution of the coccolithophores?

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