4,745 research outputs found

    Universality Class of the Reversible-Irreversible Transition in Sheared Suspensions

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    Collections of non-Brownian particles suspended in a viscous fluid and subjected to oscillatory shear at very low Reynolds number have recently been shown to exhibit a remarkable dynamical phase transition separating reversible from irreversible behaviour as the strain amplitude or volume fraction are increased. We present a simple model for this phenomenon, based on which we argue that this transition lies in the universality class of the conserved DP models or, equivalently, the Manna model. This leads to predictions for the scaling behaviour of a large number of experimental observables. Non-Brownian suspensions under oscillatory shear may thus constitute the first experimental realization of an inactive-active phase transition which is not in the universality class of conventional directed percolation.Comment: 4 pages, 2 figures, final versio

    Galactose-containing glycosylphosphatidylinositols in Trypanosoma brucei

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    Many eukaryotic surface glycoproteins, including the variant surface glycoproteins (VSGs) of Trypanosoma brucei, are synthesized with a carboxyl-terminal hydrophobic peptide extension that is cleaved and replaced by a complex glycosylphosphatidylinositol (GPI) membrane anchor within 1-5 min of the completion of polypeptide synthesis. We have reported the purification and partial characterization of candidate precursor glycolipids (P2 and P3) from T. brucei. P2 and P3 contain ethanolamine-phosphate-Man alpha 1-2Man alpha 1-6Man alpha 1-GlcN linked glycosidically to an inositol residue, as do all the GPI anchors that have been structurally characterized. The anchors on mature VSGs contain a heterogenously branched galactose structure attached alpha 1-3 to the mannose residue adjacent to the glucosamine. We report the identification of free GPIs that appear to be similarly galactosylated. These glycolipids contain diacylglycerol and alpha-galactosidase-sensitive glycan structures which are indistinguishable from the glycans derived from galactosylated VSG GPI anchors. We discuss the relevance of these galactosylated GPIs to the biosynthesis of VSG GPI anchors

    Transfer of glycosyl-phosphatidylinositol membrane anchors to polypeptide acceptors in a cell-free system

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    Glycosylinositol phospholipid (GPI) membrane anchors are the sole means of membrane attachment of a large number of cell surface proteins, including the variant surface glycoproteins (VSGs) of the parasitic protozoan, Trypanosoma brucei. Biosynthetic data suggest that GPI-anchored proteins are synthesized with carboxy-terminal extensions that are immediately replaced by GPI, suggesting the existence of preformed GPI species available for transfer to the nascent protein in the ER. Candidate precursor glycolipids having a linear sequence indistinguishable from the conserved core structure found on all GPI anchors, have been characterized in T. brucei. In this paper we describe the transfer of three GPI variants to endogenous VSG in vitro. GPI addition is not reduced by inhibitors of protein synthesis and does not require ATP or GTP, consistent with a transpeptidation mechanism

    Finfish resources around Andaman and Nicobar islands

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    The average catch rate of finfishes obtained by FORV Sagar Sampada from the survey area in the Andaman Sea was 259 kg/hr and the yield ranged from 8.6 to 1260 kg/hr. Silver bellies was the most abundant component (37.5%) with a catch rate of 96.9 kg/hr. Carangids, elasmobranchs and perches accounted for 20.3%, 11.9% and 8.0% of the total catch and the corresponding catch rates were 52.5, 31.1 and 20.8 kg/hr respectively. The highest catch rate of 1260 kg/hr was recorded from 13°10'N - 92°37'E at a depth of 65m. The catch rate indicated that the depth zone 51-100 m is productive and yielded 84.7% of the total catch at a catch rate of 501.4 kg/hr. Although the pelagic trawl was operated at 38 stations, the catch realised was neghgible (0.83 kg/hr)

    Consultancy services in marine fisheries- A profile of technologies and experts

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    The ICAR system currently needs very effective partnership between the researchers and the user groups. The Central Marine Fisheries Research Institute, a premier Institute under the ICAR, has taken effective steps to introduce the services and technologies in the marine fisheries sector, achieved over the last 50 years R & D activities. With a viev/ to institutionalising transfer of technologies, the institute has constituted a Consultancy Processing Cell (CPC) in 1997 for effectively serving the needs of our clients, through the short term and long term trainings, consultancies, contract services and contract research

    Using museum objects to improve wellbeing in mental health service users and neurological rehabilitation clients

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    Background: This study sought to determine the effects of a heritage-in-health intervention on well-being. Benefits of arts-in-health interventions are relatively well-documented yet little robust research has been conducted using heritage-in-health interventions, such as those involving museum objects. Method: Hospital patients (n = 57) participated in semi-structured, 30–40 minute facilitated interview sessions, discussing and handling museum objects comprising selections of six artefacts and specimens loaned from archaeology, art, geology and natural history collections. Well-being measures (Positive Affect Negative Affect Scale, Visual Analogue Scales) evaluated the sessions while inductive and deductive thematic analysis investigated psycho-educational features accounting for changes. Results: Comparison of pre- and post-session quantitative measures showed significant increases in well-being and happiness. Qualitative investigation revealed thinking and meaning-making opportunities for participants engaged with objects. Conclusion: Heritage-in-health sessions enhanced positive mood and social interaction, endorsing the need for provision of well-being-related museum and gallery activities for socially excluded or vulnerable healthcare audiences

    Mini-clusters

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    Experimental results of mini-clusters observed in Chacaltaya emulsion chamber no.19 are summarized. The study was made on 54 single core shower upper and 91 shower clusters of E(gamma) 10 TeV from 30 families which are visible energy greater than 80 TeV and penetrate through both upper and lower detectors of the two-story chamber. The association of hadrons in mini-cluster is made clear from their penetrative nature and microscopic observation of shower continuation in lower chamber. Small P sub t (gamma) of hadrons in mini-clusters remained in puzzle
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