136 research outputs found

    An exploration of the function of the lateral nerve and the femoral chordotonal organ in the African desert locust (Schistocerca gregaria)

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    An investigation of proprioception in the African Desert Locust (Schistocerca gregaria) is the basis of the following work. Experiments were performed on the adults and 5th instars to investigate the relation between the size of the animal and their jumping and kicking ability. This lead to a study of the effects of proprioception, specifically proprioception of the lateral nerve and the chordotonal organ on the jump and kick of adults. In order to study these effects, the simplest method was used. The lateral nerves and chordotonal organs (of the metathoracic leg) were severed, both separately, and in combination. The consequences of this loss of information about the position of the tibia in relation to the femur resulting, was judged by the behavioural and electrophysiological effects on the jump and kick of the locust. Results indicate that the loss of the information supplied via the lateral nerve is not sufficient to significantly alter the jumping or kicking performance of the animal, and neither is that loss resulting from the severance of the chordotonal organ. Loss of information from both proprioceptors appeared to prohibit kicking in the locust, but it did not prevent the locust from jumping. This surprising finding was taken as meaning that when the locust jumps, it can get positional information from other sources, such as tibial-tarsal chordotonal organs, which are in contact with the ground prior to the jump, and that this information is sufficient to enable the expression of the motor programme. However, these additional sources of information are not available when the locust kicks, and thus the motor programme is not expressed

    A Naturally Selected Dimorphism within the HLA-B44 Supertype Alters Class I Structure, Peptide Repertoire, and T Cell Recognition

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    HLA-B*4402 and B*4403 are naturally occurring MHC class I alleles that are both found at a high frequency in all human populations, and yet they only differ by one residue on the α2 helix (B*4402 Asp156→B*4403 Leu156). CTLs discriminate between HLA-B*4402 and B*4403, and these allotypes stimulate strong mutual allogeneic responses reflecting their known barrier to hemopoeitic stem cell transplantation. Although HLA-B*4402 and B*4403 share >95% of their peptide repertoire, B*4403 presents more unique peptides than B*4402, consistent with the stronger T cell alloreactivity observed toward B*4403 compared with B*4402. Crystal structures of B*4402 and B*4403 show how the polymorphism at position 156 is completely buried and yet alters both the peptide and the heavy chain conformation, relaxing ligand selection by B*4403 compared with B*4402. Thus, the polymorphism between HLA-B*4402 and B*4403 modifies both peptide repertoire and T cell recognition, and is reflected in the paradoxically powerful alloreactivity that occurs across this “minimal” mismatch. The findings suggest that these closely related class I genes are maintained in diverse human populations through their differential impact on the selection of peptide ligands and the T cell repertoire

    A Raman spectroscopic study of arsenite and thioarsenite species in aqueous solution at 25°C

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    The Raman spectra of thioarsenite and arsenite species in aqueous solution were obtained at room temperature. Solutions at constant ΣAs + ΣS of 0.1 and 0.5 mol kg(-1 )were prepared with various ΣS/ΣAs ratios (0.1–9.0) and pH values (~7–13.2). Our data suggest that the speciation of As under the conditions investigated is more complicated than previously thought. The Raman measurements offer evidence for at least six separate S-bearing As species whose principal bands are centered near 365, 385, 390, 400, 415 and 420 cm(-1). The data suggest that at least two different species may give rise to bands at 385 cm(-1), bringing the probable minimum number of species to seven. Several additional species are possible but could not be resolved definitively. In general, the relative proportions of these species are dependent on total As concentration, ΣS/ΣAs ratio and pH. At very low ΣS/ΣAs ratios we also observe Raman bands attributable to the dissociation products of H(3)AsO(3)(aq). Although we were unable to assign precise stoichiometries for the various thioarsenite species, we were able to map out general pH and ΣS/ΣAs conditions under which the various thioarsenite and arsenite species are predominant. This study provides a basis for more detailed Raman spectroscopic and other types of investigations of the nature of thioarsenite species

    Dark sectors 2016 Workshop: community report

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    This report, based on the Dark Sectors workshop at SLAC in April 2016, summarizes the scientific importance of searches for dark sector dark matter and forces at masses beneath the weak-scale, the status of this broad international field, the important milestones motivating future exploration, and promising experimental opportunities to reach these milestones over the next 5-10 years

    Simplified Models for LHC New Physics Searches

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    This document proposes a collection of simplified models relevant to the design of new-physics searches at the LHC and the characterization of their results. Both ATLAS and CMS have already presented some results in terms of simplified models, and we encourage them to continue and expand this effort, which supplements both signature-based results and benchmark model interpretations. A simplified model is defined by an effective Lagrangian describing the interactions of a small number of new particles. Simplified models can equally well be described by a small number of masses and cross-sections. These parameters are directly related to collider physics observables, making simplified models a particularly effective framework for evaluating searches and a useful starting point for characterizing positive signals of new physics. This document serves as an official summary of the results from the "Topologies for Early LHC Searches" workshop, held at SLAC in September of 2010, the purpose of which was to develop a set of representative models that can be used to cover all relevant phase space in experimental searches. Particular emphasis is placed on searches relevant for the first ~50-500 pb-1 of data and those motivated by supersymmetric models. This note largely summarizes material posted at http://lhcnewphysics.org/, which includes simplified model definitions, Monte Carlo material, and supporting contacts within the theory community. We also comment on future developments that may be useful as more data is gathered and analyzed by the experiments.Comment: 40 pages, 2 figures. This document is the official summary of results from "Topologies for Early LHC Searches" workshop (SLAC, September 2010). Supplementary material can be found at http://lhcnewphysics.or

    Expansion of HCV treatment access to people who have injected drugs through effective translation of research into public health policy:Scotland's experience

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    Seven years have elapsed since the Scottish Government launched its Hepatitis C Action Plan – a Plan to improve services to prevent transmission of infection, particularly among people who inject drugs (PWID), identify those infected and ensure those infected receive optimal treatment. The Plan was underpinned by industrial scale funding (around £100 million, in addition to the general NHS funding, will have been invested by 2015), and a web of accountable national and local multi-disciplinary multi-agency networks responsible for the planning, development and delivery of services. Initiatives ranged from the introduction of testing in specialist drug services through finger-prick blood sampling by non-clinical staff, to the setting of government targets to ensure rapid scale-up of antiviral therapy. The Plan was informed by comprehensive national monitoring systems, indicating the extent of the problem not just in terms of numbers infected, diagnosed and treated but also the more penetrative data on the number advancing to end-stage liver disease and death, and also through compelling modelling work demonstrating the potential beneficial impact of scaling-up therapy and the mounting cost of not acting. Achievements include around 50% increase in the proportion of the infected population diagnosed (38% to 55%); a sustained near two-and-a-half fold increase in the annual number of people initiated onto therapy (470 to 1050) with more pronounced increases among PWID (300 to 840) and prisoners (20 to 140); and reversing of an upward trend in the overall number of people living with chronic infection. The Action Plan has demonstrated that a Government-backed, coordinated and invested approach can transform services and rapidly improve the lives of thousands. Cited as “an impressive example of a national strategy” by the Global Commission on Drug Policy, the Scottish Plan has also provided fundamental insights of international relevance into the management of HCV among PWID

    Chicken TREM-B1, an Inhibitory Ig-Like Receptor Expressed on Chicken Thrombocytes

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    Triggering receptors expressed on myeloid cells (TREM) form a multigene family of immunoregulatory Ig-like receptors and play important roles in the regulation of innate and adaptive immunity. In chickens, three members of the TREM family have been identified on chromosome 26. One of them is TREM-B1 which possesses two V-set Ig-domains, an uncharged transmembrane region and a long cytoplasmic tail with one ITSM and two ITIMs indicating an inhibitory function. We generated specific monoclonal antibodies by immunizing a Balb/c mouse with a TREM-B1-FLAG transfected BWZ.36 cell line and tested the hybridoma supernatants on TREM-B1-FLAG transfected 2D8 cells. We obtained two different antibodies specific for TREM-B1, mab 7E8 (mouse IgG1) and mab 1E9 (mouse IgG2a) which were used for cell surface staining. Single and double staining of different tissues, including whole blood preparations, revealed expression on thrombocytes. Next we investigated the biochemical properties of TREM-B1 by using the specific mab 1E9 for immunoprecipitation of either lysates of surface biotinylated peripheral blood cells or stably transfected 2D8 cells. Staining with streptavidin coupled horse radish peroxidase revealed a glycosylated monomeric protein of about 50 kDa. Furthermore we used the stably transfected 2D8 cell line for analyzing the cytoplasmic tyrosine based signaling motifs. After pervanadate treatment, we detected phosphorylation of the tyrosine residues and subsequent recruitment of the tyrosine specific protein phosphatase SHP-2, indicating an inhibitory potential for TREM-B1. We also showed the inhibitory effect of TREM-B1 in chicken thrombocytes using a CD107 degranulation assay. Crosslinking of TREM-B1 on activated primary thrombocytes resulted in decreased CD107 surface expression of about 50-70%

    The acute management of haemorrhage, surgery and overdose in patients receiving dabigatran

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    Dabigatran is an oral direct thrombin inhibitor (DTI) licensed for stroke prevention in atrial fibrillation and likely to be soon approved in Europe for treatment of venous thrombosis. Predictable pharmacokinetics and a reduced risk of intracranial haemorrhage do not negate the potential risk of haemorrhage. Unlike warfarin, there is no reversal agent and measurement of the anticoagulant effect is not ‘routine’. The prothrombin time/international normalised ratio response to dabigatran is inconsistent and should not be measured when assessing a patient who is bleeding or needs emergency surgery. The activated partial thromboplastin time (APTT) provides a qualitative measurement of the anticoagulant effect of dabigatran. Knowledge of the time of last dose is important for interpretation of the APTT. Commercially available DTI assays provide a quantitative measurement of active dabigatran concentration in the plasma. If a patient receiving dabigatran presents with bleeding: omit/delay next dose of dabigatran; measure APTT and thrombin time (consider DTI assay if available); administer activated charcoal, with sorbitol, if within 2 h of dabigatran ingestion; give tranexamic acid (1 g intravenously if significant bleeding); maintain renal perfusion and urine output to aid dabigatran excretion. Dabigatran exhibits low protein binding and may be removed by dialysis. Supportive care should form the mainstay of treatment. If bleeding is life/limb threatening, consider an additional haemostatic agent. There is currently no evidence to support the choice of one haemostatic agent (FEIBA, recombinant factor VIIa, prothrombin complex concentrates) over another. Choice will depend on access to and experience with available haemostatic agent(s)
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