805 research outputs found

    Making the longest sugars: a chemical synthesis of heparin-related [4](n) oligosaccharides from 16-mer to 40-mer

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    The chemical synthesis of long oligosaccharides remains a major challenge. In particular, the synthesis of glycosaminoglycan (GAG) oligosaccharides belonging to the heparin and heparan sulfate (H/HS) family has been a high profile target, particularly with respect to the longer heparanome. Herein we describe a synthesis of the longest heparin-related oligosaccharide to date and concurrently provide an entry to the longest synthetic oligosaccharides of any type yet reported. Specifically, the iterative construction of a series of [4]n-mer heparin-backbone oligosaccharides ranging from 16-mer through to the 40-mer in length is described. This demonstrates for the first time the viability of generating long sequence heparanoids by chemical synthesis, via practical solution-phase synthesis. Pure-Shift HSQC NMR provides a dramatic improvement in anomeric signal resolution, allowing full resolution of all 12 anomeric protons and extrapolation to support anomeric integrity of the longer species. A chemically pure 6-O-desfulfated GlcNS-IdoAS icosasaccharide (20-mer) represents the longest pure synthetic heparin-like oligosaccharide

    Innovative development of the inspired sinewave device to measure lung functions and inhomogeneity for diagnosis and evaluations of early lung diseases

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    Surprisingly, lung disease is still one of the leading causes of deaths in the developed countries, including UK. According to the UK National Health Service (NHS), Chronic Obstructive Pulmonary Disease (COPD) is the fifth biggest killer disease in the UK, killing approximately 25,000 people a year. This prob-lem is even worse in developing countries such as Vietnam, India and China, where air pollution is a big problem and the disease awareness is under-recognised. The NHS has set out one of its challenges is to identify people with lung disease earlier in the disease’s development pathway, in order to pro-vide more effective and timely intervention and treatment. This paper presents a novel Inspired Sinewave Device (ISD) to measure lung function and inhomogeneity. Both set of infor-mation are important for diagnosis and detection of early lung diseases. ISD has the potential to replace or supplement the traditional spirometry in the routine lung function testing. The paper describes both the principle of ISD and a set of experi-mental results demonstrating the capability of ISD to asymp-totically detect asthmatic symptoms. Finally the paper discuss-es the future plan, including the testing of 300+ COPD patients at the Oxford Respiratory Trials Unit in UK, and the potential collaborations among research institutions in Vietnam and UK about cost-effective and innovative developments of smart devices, biosensors, lab-on-chips and telehealth solutions for the routine lung function testing, diagnosis and evaluations of early lung diseases

    On the geometry of C^3/D_27 and del Pezzo surfaces

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    We clarify some aspects of the geometry of a resolution of the orbifold X = C3/D_27, the noncompact complex manifold underlying the brane quiver standard model recently proposed by Verlinde and Wijnholt. We explicitly realize a map between X and the total space of the canonical bundle over a degree 1 quasi del Pezzo surface, thus defining a desingularization of X. Our analysis relys essentially on the relationship existing between the normalizer group of D_27 and the Hessian group and on the study of the behaviour of the Hesse pencil of plane cubic curves under the quotient.Comment: 23 pages, 5 figures, 2 tables. JHEP style. Added references. Corrected typos. Revised introduction, results unchanged

    Components as processes: an exercise in coalgebraic modeling

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    IFIP TC6/WG6.1. Fourth International Conference on Formal Methods for Open Object-Based Distributed Systems (FMOODS 2000) September 6–8, 2000, Stanford, California, USASoftware components, arising, typically, in systems ’ analysis and design, are characterized by a public interface and a private encapsulated state. They persist (and evolve) in time, according to some behavioural patterns. This paper is an exercise in modeling such components as coalgebras for some kinds of endofunctors on , capturing both (interface) types and behavioural aspects. The construction of component categories, cofibred over the interface space, emerges by generalizing the usual notion of a coalgebra morphism. A collection of composition operators as well as a generic notion of bisimilarity, are discussed

    Study of Bc+B_c^+ decays to the K+Kπ+K^+K^-\pi^+ final state and evidence for the decay Bc+χc0π+B_c^+\to\chi_{c0}\pi^+

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    A study of Bc+K+Kπ+B_c^+\to K^+K^-\pi^+ decays is performed for the first time using data corresponding to an integrated luminosity of 3.0 fb1\mathrm{fb}^{-1} collected by the LHCb experiment in pppp collisions at centre-of-mass energies of 77 and 88 TeV. Evidence for the decay Bc+χc0(K+K)π+B_c^+\to\chi_{c0}(\to K^+K^-)\pi^+ is reported with a significance of 4.0 standard deviations, resulting in the measurement of σ(Bc+)σ(B+)×B(Bc+χc0π+)\frac{\sigma(B_c^+)}{\sigma(B^+)}\times\mathcal{B}(B_c^+\to\chi_{c0}\pi^+) to be (9.83.0+3.4(stat)±0.8(syst))×106(9.8^{+3.4}_{-3.0}(\mathrm{stat})\pm 0.8(\mathrm{syst}))\times 10^{-6}. Here B\mathcal{B} denotes a branching fraction while σ(Bc+)\sigma(B_c^+) and σ(B+)\sigma(B^+) are the production cross-sections for Bc+B_c^+ and B+B^+ mesons. An indication of bˉc\bar b c weak annihilation is found for the region m(Kπ+)<1.834GeV ⁣/c2m(K^-\pi^+)<1.834\mathrm{\,Ge\kern -0.1em V\!/}c^2, with a significance of 2.4 standard deviations.Comment: All figures and tables, along with any supplementary material and additional information, are available at https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2016-022.html, link to supplemental material inserted in the reference

    Host-directed therapy in diabetes and tuberculosis comorbidity, towards global TB elimination

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    ...Host-directed therapy could potentially revolutionise tuberculosis control, as adjunct to traditional antibiotics for the treatment of tuberculosis disease, and as a strategy to prevent disease progression following Mycobacterium tuberculosis infection. The growing type 2 diabetes pandemic is hampering tuberculosis control worldwide, as people with diabetes have an increased risk of developing tuberculosis disease as well as worse treatment outcomes. Pulmonary tuberculosis is characterised by an inflammatory response which can cause alveolar tissue destruction and cavitation, and this inflammation is exacerbated in people with tuberculosis-diabetes comorbidity. Thus, the reduction of the inflammatory response is a key goal of host-directed therapy to dampen immunopathology, but it is vital that the inflammatory response is not suppressed too much or the immune system will not be able to react to Mycobacterium tuberculosis and mycobacterial replication will intensify. Furthermore, the type I interferon response and host cell metabolism are further dysregulated in tuberculosis-diabetes comorbidity, likely contributing to poor treatment outcomes. Achieving the right balance in terms of modulating the inflammatory and immune responses, both quantitatively and temporally, is more complex in tuberculosis diabetes comorbidity and this population should be included specifically in clinical trials of new regimen. In this regard, mathematical modelling has a key role in elucidating which biological pathways should be targeted in different people. Host-directed therapy for people with tuberculosis-diabetes comorbidity will reduce immunopathology and post-tuberculosis lung disease, as well as boost microbiological cure and treatment outcomes, and thus help in the fight towards global tuberculosis elimination.No Funding

    Observation of Bc+ →j /ψD (∗)K (∗) decays

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    A search for the decays B+c→J/ψD(*)0K+ and B+c→J/ψD(*)+K*0 is performed with data collected at the LHCb experiment corresponding to an integrated luminosity of 3 fb−1. The decays B+c→J/ψ0K+ and B+c→J/ψD*0K+ are observed for the first time, while first evidence is reported for the B+c→JψD*+K*0 and B+c→J/ψD+K*0 decays. The branching fractions of these decays are determined relative to the B+c→J/ψπ+ decay. The B+c mass is measured, using the J/ψD0K+ final state, to be 6274.28±1.40(stat)±0.32(syst) MeV/c2. This is the most precise single measurement of the B+c mass to date

    Risky business: factor analysis of survey data – assessing the probability of incorrect dimensionalisation

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    This paper undertakes a systematic assessment of the extent to which factor analysis the correct number of latent dimensions (factors) when applied to ordered categorical survey items (so-called Likert items). We simulate 2400 data sets of uni-dimensional Likert items that vary systematically over a range of conditions such as the underlying population distribution, the number of items, the level of random error, and characteristics of items and item-sets. Each of these datasets is factor analysed in a variety of ways that are frequently used in the extant literature, or that are recommended in current methodological texts. These include exploratory factor retention heuristics such as Kaiser’s criterion, Parallel Analysis and a non-graphical scree test, and (for exploratory and confirmatory analyses) evaluations of model fit. These analyses are conducted on the basis of Pearson and polychoric correlations.We find that, irrespective of the particular mode of analysis, factor analysis applied to ordered-categorical survey data very often leads to over-dimensionalisation. The magnitude of this risk depends on the specific way in which factor analysis is conducted, the number of items, the properties of the set of items, and the underlying population distribution. The paper concludes with a discussion of the consequences of overdimensionalisation, and a brief mention of alternative modes of analysis that are much less prone to such problems

    Study of production and cold nuclear matter effects in pPb collisions at=5 TeV

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    Production of mesons in proton-lead collisions at a nucleon-nucleon centre-of-mass energy = 5 TeV is studied with the LHCb detector. The analysis is based on a data sample corresponding to an integrated luminosity of 1.6 nb(-1). The mesons of transverse momenta up to 15 GeV/c are reconstructed in the dimuon decay mode. The rapidity coverage in the centre-of-mass system is 1.5 < y < 4.0 (forward region) and -5.0 < y < -2.5 (backward region). The forward-backward production ratio and the nuclear modification factor for (1S) mesons are determined. The data are compatible with the predictions for a suppression of (1S) production with respect to proton-proton collisions in the forward region, and an enhancement in the backward region. The suppression is found to be smaller than in the case of prompt J/psi mesons

    A study of the Z production cross-section in pp collisions at √s = 7 using tau final states

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    A measurement of the inclusive Z → ττ cross-section in pp collisions at √s =7 is presented based on a dataset of 1.0 fb[superscript −1] collected by the LHCb detector. Candidates for Z → τ τ decays are identified through reconstructed final states with two muons, a muon and an electron, a muon and a hadron, or an electron and a hadron. The production cross-section for Z bosons, with invariant mass between 60 and 120 GeV/c[superscript 2], which decay to τ leptons with transverse momenta greater than 20 GeV/c and pseudorapidities between 2.0 and 4.5, is measured to be σ[subscript pp]→Z→ττ = 71.4 ± 3.5 ± 2.8 ± 2.5 pb; the first uncertainty is statistical, the second is systematic, and the third is due to the uncertainty on the integrated luminosity. The ratio of the cross-sections for Z → τ τ to Z → μμ is determined to be 0.93 ± 0.09, where the uncertainty is the combination of statistical, systematic, and luminosity uncertainties of the two measurements.National Science Foundation (U.S.
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