21,817 research outputs found

    Energy and system size dependence of charged particle elliptic flow and v_2/\eps scaling

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    We report measurements of charged particle elliptic flow %(v2v_2) at mid-rapidity in Au+Au and Cu+Cu collisions at sNN=62\sqrt{s_{_{NN}}}=62 and 200 GeV. Using correlations between main STAR TPC and Forward TPCs ensures minimal bias due to non-flow effects. We further investigate the effect of flow fluctuations on v_2/\eps scaling studying initial geometry eccentricity fluctuations in Monte-Carlo Glauber model, consistent with STAR direct measurements of elliptic flow fluctuations. It is found that accounting for the effect of flow fluctuations improves v_2/\eps scaling.Comment: 4 pages, Quark Matter 2006 proceeding

    Defect dynamics of bistable latching

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    Energy and system size dependence of elliptic flow: using rapidity gaps to suppress non-flow contribution

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    In this talk I present new STAR results on measurements of integrated elliptic flow at midrapidity in Au+Au and Cu+Cu collisions at sNN=\sqrt{s_{NN}}=200 and 62 GeV energies. These results have been obtained from azimuthal correlations between particles in the main STAR TPC and two forward TPCs, and are to a large extent free from so-called non-flow correlations. These results along with the previously reported values of ``participant'' eccentricity taking into account eccentricity fluctuations are used for testing the v_2/\eps scaling, which is found to hold relatively well.Comment: 4 pages. Talk at CIPANP 2006, 9th Conference on the Intersections of Particle and Nuclear Physics, May 30-June 3, 2006, Rio Grande, Puerto Ric

    Macrostructural and Microstructural White Matter Alterations Are Associated with Apathy across the Clinical Alzheimer’s Disease Spectrum

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    Apathy is the commonest neuropsychiatric symptom in Alzheimer’s disease (AD). Previous findings suggest that apathy is caused by a communication breakdown between functional neural networks involved in motivational–affective processing. This study investigated the relationship between white matter (WM) damage and apathy in AD. Sixty-one patients with apathy (AP-PT) and 61 without apathy (NA-PT) were identified from the Alzheimer’s Disease Neuroimaging Initiative (ADNI) database and matched for cognitive status, age and education. Sixty-one cognitively unimpaired (CU) participants were also included as controls. Data on cognitive performance, cerebrospinal fluid biomarkers, brain/WM hyperintensity volumes and diffusion tensor imaging indices were compared across groups. No neurocognitive differences were found between patient groups, but the AP-PT group had more severe neuropsychiatric symptoms. Compared with CU participants, only apathetic patients had deficits on the Clock Drawing Test. AP-PT had increased WM damage, both macrostructurally, i.e., larger WM hyperintensity volume, and microstructurally, i.e., increased radial/axial diffusivity and reduced fractional anisotropy in the fornix, cingulum, anterior thalamic radiations and superior longitudinal and uncinate fasciculi. AP-PT showed signs of extensive WM damage, especially in associative tracts in the frontal lobes, fornix and cingulum. Disruption in structural connectivity might affect crucial functional inter-network communication, resulting in motivational deficits and worse cognitive decline

    Predicting the Remaining Lifespan and Cultivation-Related Loss of Osteogenic Capacity of Bone Marrow Multipotential Stromal Cells Applicable across a Broad Donor Age Range

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    Background and Objectives. Culture expanded multipotential stromal cells (MSCs) have considerable potential for bone regeneration therapy but their wider use is constrained by the lack of simple and predictive assays of functional potency. Extended passaging leads to loss of multipotency but speed of decline depends on MSC donor age. The aim of this study was to develop an assay predictive of MSC culture longevity applicable to a broad donor age range. Materials and Methods. Bone marrow (BM, =7) was obtained from a diverse range (2–72 years) of healthy donors. MSCs were culture expanded to senescence and their osteoprogenitor content, gene expression profiles, epigenetic signature, and telomere behaviour were measured throughout. Output data was combined for modelling purposes. Results. Regardless of donor age, cultures’ osteoprogenitor content correlated better with remaining lifespan (population doublings before senescence, PD-BS) than proliferative history (accrued PDs). Individual gene’s expression or telomere length did not predict PD-BS but methylation of individual CpG islands did, PRAMEF2 in particular ( = 0.775). Coupling the steep relationship of relative SPARC expression with PD-BS ( = −0.753) the formula SPARC × 1/PREMEF2 gave an improved correlation ( = −0.893).Conclusion. A formula based on SPARC mRNA and PRAMEF2 methylation may be used to predict remaining BM-MSC longevity and related loss of multipotentiality independent of donor age

    Solid-state photoreactivity of 9-substituted acridizinium bromide salts

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    A series of substituted acridizinium bromides was studied to determine how substituents affect the regioselectivity of the solid-state [4 + 4] photodimerisation.This is the final version. It was first published by RSC at http://pubs.rsc.org/en/Content/ArticleLanding/2014/CE/C4CE01622J#!divAbstrac

    Global transcript and phenotypic analysis of yeast cells expressing Ssa1, Ssa2, Ssa3 or Ssa4 as sole source of cytosolic Hsp70-Ssa chaperone activity.

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    BACKGROUND: Cytosolic Hsp70 is a ubiquitous molecular chaperone that is involved in responding to a variety of cellular stresses. A major function of Hsp70 is to prevent the aggregation of denatured proteins by binding to exposed hydrophobic regions and preventing the accumulation of amorphous aggregates. To gain further insight into the functional redundancy and specialisation of the highly homologous yeast Hsp70-Ssa family we expressed each of the individual Ssa proteins as the sole source of Hsp70 in the cell and assessed phenotypic differences in prion propagation and stress resistance. Additionally we also analysed the global gene expression patterns in yeast strains expressing individual Ssa proteins, using microarray and RT-qPCR analysis. RESULTS: We confirm and extend previous studies demonstrating that cells expressing different Hsp70-Ssa isoforms vary in their ability to propagate the yeast [PSI+] prion, with Ssa3 being the most proficient. Of the four Ssa family members the heat inducible isoforms are more proficient in acquiring thermotolerance and we show a greater requirement than was previously thought, for cellular processes in addition to the traditional Hsp104 protein disaggregase machinery, in acquiring such thermotolerance. Cells expressing different Hsp70-Ssa isoforms also display differences in phenotypic response to exposure to cell wall damaging and oxidative stress agents, again with the heat inducible isoforms providing better protection than constitutive isoforms. We assessed global transcriptome profiles for cells expressing individual Hsp70-Ssa isoforms as the sole source of cytosolic Hsp70, and identified a significant difference in cellular gene expression between these strains. Differences in gene expression profiles provide a rationale for some phenotypic differences we observed in this study. We also demonstrate a high degree of correlation between microarray data and RT-qPCR analysis for a selection of genes. CONCLUSIONS: The Hsp70-Ssa family provide both redundant and variant-specific functions within the yeast cell. Yeast cells expressing individual members of the Hsp70-Ssa family as the sole source of Ssa protein display differences in global gene expression profiles. These changes in global gene expression may contribute significantly to the phenotypic differences observed between the Hsp70-Ssa family members

    Tirisporella gen. nov., an ascomycete from the mangrove palm Nypa fruticans

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    Tirisporella beccariana comb.nov. is redescribed from decomposing leaf petiole (or rachis) bases of Nypa fruticans recently collected in Malaysia and the Philippiines. The superficial ascomata bear bitunicate asci with (3-)5(-7)-septate ascospores that are brown and verrucose, except for the prominent hyaline basal cell, and furnished with a distinctive apical appendage that arises from the spore wall. Te ultrastructure of the fungus is contrasted with that of species of Corollospora and Corallicola, with particular reference to the mode of ascospore appendage formation. The species was originally described from a Sarawak collection as Sphaeria becariana and later transferred to Melanomma and given the new name Melanomma cesatianum. Gibberidea nipae is a synonym. The recent collections were compared with type specimens. The fungus is not properly placed in Melanomma or Gibberidea or other known genera and a new genus Tiriporella is described.published_or_final_versio
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