81 research outputs found

    The B(s)→D(s)lνB_{(s)} \to D_{(s)}l\nu Decay with Highly Improved Staggered Quarks and NRQCD

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    We report on progress of a lattice QCD calculation of the B→DlνB\to Dl\nu and Bs→DslνB_s\to D_s l\nu semileptonic form factors. We use a relativistic staggered action (HISQ) for light and charm quarks, and an improved non-relativistic (NRQCD) action for bottom, on the second generation MILC ensembles.Comment: Presented at Lattice 2017, the 35th International Symposium on Lattice Field Theory at Granada, Spain (18-24 June 2017

    Abdominal functional electrical stimulation to enhance mechanical insufflation-exsufflation

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    Context: Respiratory complications, attributed to the build-up of secretions in the airway, are a leading cause of rehospitalisation for the tetraplegic population. Previously, we observed that the application of Abdominal Functional Electrical Stimulation (AFES) improved cough function and increased demand for secretion removal, suggesting AFES may aid secretion clearance. Clinically, secretion clearance is commonly achieved by using Mechanical insufflation-exsufflation (MI-E) to simulate a cough. In this study the feasibility of combining AFES with MI-E is evaluated. Findings: AFES was successfully combined with MI-E at eight fortnightly assessment sessions conducted with one sub-acute participant with tetraplegia. By using the signal from a pressure sensor, integrated with the MI-E device, AFES was correctly applied in synchrony with MI-E with an accuracy of 96.7%. Acute increases in exhaled volume and peak flow were observed during AFES assisted MI-E, compared to MI-E alone, at six of eight assessment sessions. Conclusion: The successful integration of AFES with MI-E at eight assessment sessions demonstrates the feasibility of this technique. The acute increases in respiratory function observed at the majority of assessment sessions generate the hypothesis that AFES assisted MI-E may be more effective for secretion clearance than MI-E alone

    Semileptonic b → c form factors from lattice quantum chromodynamics

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    This thesis gives details and results of calculations of form factors for a number of b→cb\to c transitions using lattice quantum chromodynamics. We apply two complementary approaches to dealing with the heavy bb quark in the lattice context (the NRQCD approach and heavy-HISQ approach). We find the latter to be more promising for future calculations

    Abdominal functional electrical stimulation to assist ventilator weaning in acute tetraplegia: a cohort study

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    Background Severe impairment of the major respiratory muscles resulting from tetraplegia reduces respiratory function, causing many people with tetraplegia to require mechanical ventilation during the acute stage of injury. Abdominal Functional Electrical Stimulation (AFES) can improve respiratory function in non-ventilated patients with sub-acute and chronic tetraplegia. The aim of this study was to investigate the clinical feasibility of using an AFES training program to improve respiratory function and assist ventilator weaning in acute tetraplegia.<p></p> Methods AFES was applied for between 20 and 40 minutes per day, five times per week on four alternate weeks, with 10 acute ventilator dependent tetraplegic participants. Each participant was matched retrospectively with a ventilator dependent tetraplegic control, based on injury level, age and sex. Tidal Volume (VT) and Vital Capacity (VC) were measured weekly, with weaning progress compared to the controls.<p></p> Results Compliance to training sessions was 96.7%. Stimulated VT was significantly greater than unstimulated VT. VT and VC increased throughout the study, with mean VC increasing significantly (VT: 6.2 mL/kg to 7.8 mL/kg VC: 12.6 mL/kg to 18.7 mL/kg). Intervention participants weaned from mechanical ventilation on average 11 (sd: ± 23) days faster than their matched controls.<p></p> Conclusion The results of this study indicate that AFES is a clinically feasible technique for acute ventilator dependent tetraplegic patients and that this intervention may improve respiratory function and enable faster weaning from mechanical ventilation.<p></p&gt

    Lattice QCD form factor for Bs→D∗slν at zero recoil with nonperturbative current renormalization

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    We present details of a lattice QCD calculation of the B s → D ∗ s axial form factor at zero recoil using the highly improved staggered quark (HISQ) formalism on the second-generation MILC gluon ensembles that include up, down, strange and charm quarks in the sea. Using the HISQ action for all valence quarks means that the lattice axial vector current that couples to the W can be renormalized fully nonperturbatively, giving a result free of the perturbative matching errors that previous lattice QCD calculations have had. We calculate correlation functions at three values of the lattice spacing, and multiple b -quark masses, for physical c and s . The functional dependence on the b -quark mass can be determined and compared to heavy quark effective theory expectations, and a result for the form factor obtained at the physical value of the b -quark mass. We find F B s → D ∗ s ( 1 ) = h s A 1 ( 1 ) = 0.9020 ( 96 ) stat ( 90 ) sys . This is in agreement with earlier lattice QCD results, which use NRQCD b quarks, with a total uncertainty reduced by more than a factor of 2. We discuss implications of this result for the B → D ∗ axial form factor at zero recoil and for determinations of V c b

    Arylboronic Acid Catalyzed C-Alkylation and Allylation Reactions Using Benzylic Alcohols

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    : The arylboronic acid catalyzed dehydrative Calkylation of 1,3-diketones and 1,3-ketoesters using secondary benzylic alcohols as the electrophile is reported, forming new C−C bonds (19 examples, up to 98% yield) with the release of water as the only byproduct. The process is also applicable to the allylation of benzylic alcohols using allyltrimethylsilane as the nucleophile (12 examples, up to 96% yield)

    Aryl Boronic Acid Catalysed Dehydrative Substitution of Benzylic Alcohols for C−O Bond Formation

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    We thank the University of St Andrews and the EPSRC for the award of a DTA studentship (S.E.-D.). We would also like to thank the EPSRC, University of St Andrews, and CRITICAT Centre for Doctoral Training for financial support [Ph.D. studentships to B.M.H, E.B.M and L.J.D; Grant code: EP/L016419/1]. J.E.T thanks the Leverhulme Trust for the award of an Early Career Fellowship (Grant code: ECF-2014-005).A combination of pentafluorophenylboronic acid and oxalic acid catalyses the dehydrative substitution of benzylic alcohols with a second alcohol to form new C-O bonds. This method has been applied to the intermolecular substitution of benzylic alcohols to form symmetrical ethers, intramolecular cyclisations of diols to form aryl-substituted tetrahydrofuran and tetrahydropyran derivatives, and intermolecular crossed-etherification reactions between two different alcohols. Mechanistic control experiments have identified a potential catalytic intermediate formed between the arylboronic acid and oxalic acid.PostprintPeer reviewe

    Relative efficiency of fishing gears and investigation of resource availability in tropical demersal scalefish fisheries FRDC REPORT – PROJECT 2006/031

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    This project identified that there is substantial spatial variation in the demersal fish assemblages in the NDSF with some species more abundant in the north of the fishery and others in the south. At finer scales within sites and depths there is spatial variation associated with different habitats (e.g. sand vs sponge gardens or reef)

    Management strategies to minimize the dredging impacts of coastal development on fish and fisheries

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    Accelerating coastal development and shipping activities dictate that dredging operations will intensify, increasing potential impacts to fishes. Coastal fishes have high economic, ecological, and conservation significance and there is a need for evidencebased, quantitative guidelines on how to mitigate the impacts of dredging activities. We assess the potential risk from dredging to coastal fish and fisheries on a global scale.We then develop quantitative guidelines for two management strategies: threshold reference values and seasonal restrictions. Globally, threatened species and nearshore fisheries occur within close proximity to ports. We find that maintaining suspended sediment concentrations below 44 mg/L (15–121 bootstrapped CI) and for less than 24 hours would protect 95% of fishes from dredging-induced mortality. Implementation of seasonal restrictions during peak periods of reproduction and recruitment could further protect species from dredging impacts. This study details the first evidence-based defensible approach to minimize impacts to coastal fishes from dredging activities
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