1,303 research outputs found

    Blackcurrant Alters Physiological Responses and Femoral Artery Diameter During Sustained Isometric Contraction

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    Blackcurrant is rich in anthocyanins that may affect exercise-induced physiological responses. We examined tissue oxygen saturation, muscle activity, cardiovascular responses and femoral artery diameter during a submaximal sustained isometric contraction. In a randomised, double-blind, crossover design, healthy men (n = 13, age: 25 ± 4 years, BMI: 25 ± 3 kg·m−2, mean ± SD) ingested New Zealand blackcurrant (NZBC) extract (600 mg·day−1 CurraNZ™) or placebo (PL) for 7-days separated by 14-days washout. Participants produced isometric maximal voluntary contractions (iMVC) and a 120-s 30%iMVC of the quadriceps with electromyography (EMG), near-infrared spectroscopy, hemodynamic and ultrasound recordings. There was no effect of NZBC extract on iMVC (NZBC: 654 ± 73, PL: 650 ± 78 N). During the 30%iMVC with NZBC extract, total peripheral resistance, systolic, diastolic, and mean arterial pressure were lower with increased cardiac output and stroke volume. With NZBC extract, EMG root mean square of the vastus medialis and muscle oxygen saturation were lower with higher total haemoglobin. During the 30%iMVC, femoral artery diameter was increased with NZBC extract at 30 (6.9%), 60 (8.2%), 90 (7.7%) and 120 s (6.0%). Intake of NZBC extract for 7-days altered cardiovascular responses, muscle oxygen saturation, muscle activity and femoral artery diameter during a 120-s 30%iMVC of the quadriceps. The present study provides insight into the potential mechanisms for enhanced exercise performance with intake of blackcurrant

    Baryon Acoustic Oscillations in the Ly{\alpha} forest of BOSS DR11 quasars

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    We report a detection of the baryon acoustic oscillation (BAO) feature in the flux-correlation function of the Ly{\alpha} forest of high-redshift quasars with a statistical significance of five standard deviations. The study uses 137,562 quasars in the redshift range 2.1z3.52.1\le z \le 3.5 from the Data Release 11 (DR11) of the Baryon Oscillation Spectroscopic Survey (BOSS) of SDSS-III. This sample contains three times the number of quasars used in previous studies. The measured position of the BAO peak determines the angular distance, DA(z=2.34)D_A(z=2.34) and expansion rate, H(z=2.34)H(z=2.34), both on a scale set by the sound horizon at the drag epoch, rdr_d. We find DA/rd=11.28±0.65(1σ)1.2+2.8(2σ)D_A/r_d=11.28\pm0.65(1\sigma)^{+2.8}_{-1.2}(2\sigma) and DH/rd=9.18±0.28(1σ)±0.6(2σ)D_H/r_d=9.18\pm0.28(1\sigma)\pm0.6(2\sigma) where DH=c/HD_H=c/H. The optimal combination, DH0.7DA0.3/rd\sim D_H^{0.7}D_A^{0.3}/r_d is determined with a precision of 2%\sim2\%. For the value rd=147.4 Mpcr_d=147.4~{\rm Mpc}, consistent with the CMB power spectrum measured by Planck, we find DA(z=2.34)=1662±96(1σ) MpcD_A(z=2.34)=1662\pm96(1\sigma)~{\rm Mpc} and H(z=2.34)=222±7(1σ) kms1Mpc1H(z=2.34)=222\pm7(1\sigma)~{\rm km\,s^{-1}Mpc^{-1}}. Tests with mock catalogs and variations of our analysis procedure have revealed no systematic uncertainties comparable to our statistical errors. Our results agree with the previously reported BAO measurement at the same redshift using the quasar-Ly{\alpha} forest cross-correlation. The auto-correlation and cross-correlation approaches are complementary because of the quite different impact of redshift-space distortion on the two measurements. The combined constraints from the two correlation functions imply values of DA/rdD_A/r_d and DH/rdD_H/r_d that are, respectively, 7% low and 7% high compared to the predictions of a flat Λ\LambdaCDM cosmological model with the best-fit Planck parameters. With our estimated statistical errors, the significance of this discrepancy is 2.5σ\approx 2.5\sigma.Comment: Accepted for publication in A&A. 17 pages, 18 figure

    Fundamentals of neurogastroenterology: Basic science

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    This review examines the fundamentals of neurogastroenterology that may underlie the pathophysiology of functional GI disorders (FGIDs). It was prepared by an invited committee of international experts and represents an abbreviated version of their consensus document that will be published in its entirety in the forthcoming book and online version entitled Rome IV. It emphasizes recent advances in our understanding of the enteric nervous system, sensory physiology underlying pain, and stress signaling pathways. There is also a focus on neuroimmmune signaling and intestinal barrier function, given the recent evidence implicating the microbiome, diet, and mucosal immune activation in FGIDs. Together, these advances provide a host of exciting new targets to identify and treat FGIDs, and new areas for future research into their pathophysiology

    Autonomous GN and C for Spacecraft Exploration of Comets and Asteroids

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    A spacecraft guidance, navigation, and control (GN&C) system is needed to enable a spacecraft to descend to a surface, take a sample using a touch-and-go (TAG) sampling approach, and then safely ascend. At the time of this reporting, a flyable GN&C system that can accomplish these goals is beyond state of the art. This article describes AutoGNC, which is a GN&C system capable of addressing these goals, which has recently been developed and demonstrated to a maturity TRL-5-plus. The AutoGNC solution matures and integrates two previously existing JPL capabilities into a single unified GN&C system. The two capabilities are AutoNAV and GREX. AutoNAV is JPL s current flight navigation system, and is fairly mature with respect to flybys and rendezvous with small bodies, but is lacking capability for close surface proximity operations, sampling, and contact. G-REX is a suite of low-TRL algorithms and capabilities that enables spacecraft operations in close surface proximity and for performing sampling/contact. The development and integration of AutoNAV and G-REX components into AutoGNC provides a single, unified GN&C capability for addressing the autonomy, close-proximity, and sampling/contact aspects of small-body sample return missions. AutoGNC is an integrated capability comprising elements that were developed separately. The main algorithms and component capabilities that have been matured and integrated are autonomy for near-surface operations, terrain-relative navigation (TRN), real-time image-based feedback guidance and control, and six degrees of freedom (6DOF) control of the TAG sampling event. Autonomy is achieved based on an AutoGNC Executive written in Virtual Machine Language (VML) incorporating high-level control, data management, and fault protection. In descending to the surface, the AutoGNC system uses camera images to determine its position and velocity relative to the terrain. This capability for TRN leverages native capabilities of the original AutoNAV system, but required advancements that integrate the separate capabilities for shape modeling, state estimation, image rendering, defining a database of onboard maps, and performing real-time landmark recognition against the stored maps. The ability to use images to guide the spacecraft requires the capability for image-based feedback control. In Auto- GNC, navigation estimates are fed into an onboard guidance and control system that keeps the spacecraft guided along a desired path, as it descends towards its targeted landing or sampling site. Once near the site, AutoGNC achieves a prescribed guidance condition for TAG sampling (position/orientation, velocity), and a prescribed force profile on the sampling end-effector. A dedicated 6DOF TAG control then implements the ascent burn while recovering from sampling disturbances and induced attitude rates. The control also minimizes structural interactions with flexible solar panels and disallows any part of the spacecraft from making contact with the ground (other than the intended end-effector)
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