324 research outputs found

    The electric dipole moment of the neutron in chiral perturbation theory

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    We calculate the electric dipole moments of the neutron and the Lambda within the framework of heavy baryon chiral perturbation theory. They are induced by strong CP-violating terms of the effective Lagrangian in the presence of the vacuum angle theta_0. The construction of such a Lagrangian is outlined and we are able to give an estimate for theta_0.Comment: 17 pages, 2 figure

    The effects of two equal-volume training protocols upon strength, body composition and salivary hormones in male rugby union players

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    This study examined the effects of two equal-volume resistance-training protocols upon strength, body composition and salivary hormones in male rugby union players. Using a crossover design, 24 male rugby players completed a 4-week full-body (FB) and split-body (SB) training protocol of equal volume during the competitive season. One repetition maximum (1RM) strength, body composition via skinfold measurements and salivary testosterone (T) and cortisol (C) concentrations were assessed pre and post training. The FB and SB protocols improved upper (7.3% and 7.4%) and lower body 1RM strength (7.4% and 5.4%), whilst reducing body fat (-0.9% and -0.4%) and fat mass (-5.7% and -2.1%), respectively (all p ≤ 0.021). The SB protocol elevated T (21%) and C (50%) concentrations with a higher T/C ratio (28%) after FB training (all p ≤ 0.039). The strength changes were similar, but the body composition and hormonal results differed by protocol. Slope testing on the individual responses identified positive associations (p ≤ 0.05) between T and C concentrations and absolute 1RM strength in stronger (squat 1RM = 150.5 kg), but not weaker (squat 1RM = 117.4 kg), men. A short window of training involving FB or SB protocols can improve strength and body composition in rugby players. The similar strength gains highlight training volume as a key adaptive stimulus, although the programme structure (i.e. FB or SB) did influence the body composition and hormonal outcomes. It also appears that 1RM strength is associated with individual hormonal changes and baseline strength

    Topological susceptibility in full QCD at zero and finite temperature

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    We present a study of the topological susceptibility χ\chi on the lattice for full QCD with 2 and 4 flavours of staggered fermions at zero and finite temperature T. We find that χ\chi presents a sharp drop across the deconfinement transition. We also study the dependence of χ\chi on the quark mass at T=0: we have no conclusive evidence for the expected chiral behaviour.Comment: latex source, 8 pages, 4 figure

    A Wearable Multisensing Patch for Continuous Sweat Monitoring

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    In sport, exercise and healthcare settings, there is a need for continuous, non-invasive monitoring of biomarkers to assess human performance, health and wellbeing. Here we report the development of a flexible microfluidic platform with fully integrated sensing for on-body testing of human sweat. The system can simultaneously and selectively measure metabolite (e.g. lactate) and electrolytes (e.g. pH, sodium) together with temperature sensing for internal calibration. The construction of the platform is designed such that continuous flow of sweat can pass through an array of flexible microneedle type of sensors (50 µm diameter) incorporated in a microfluidic channel. Potentiometric sodium ion sensors were developed using a polyvinyl chloride (PVC) functional membrane deposited on an electrochemically deposited internal layer of Poly(3,4-ethylenedioxythiophene) (PEDOT) polymer. The pH sensing layer is based on a highly sensitive membrane of iridium oxide (IrOx). The amperometric-based lactate sensor consists of doped enzymes deposited on top of a semipermeable copolymer mebrane and outer polyurethane layers. Real-time data were collected from human subjects during cycle ergometry and treadmill running. A detailed comparison of sodium, lactate and cortisol from saliva is reported, demonstrating the potential of the multi-sensing platform for tracking these outcomes. In summary, a fully integrated sensor for continuous, simultaneous and selective measurement of sweat metabolites, electrolytes and temperature was achieved using a flexible microfluidic platform. This system can also transmit information wirelessly for ease of collection and storage, with the potential for real-time data analytics

    Correlator of Topological Charge Densities in Instanton Model in QCD

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    The QCD sum rule for the correlator of topological charge densities and related to it longitudinal part of the correlator of singlet axial currents is considered in the framework of instanton model. The coupling constant of eta'-meson with the singlet axial current is determined. Its value appears to be in a good coincidence with the value determined recently from the connection of the part of proton spin, carried by u,d,s quarks, with the derivative of QCD topological susceptibility. From the same sum rule eta-eta' mixing angle is found in the framework of two mixing angles model. Its value is close to that found in the chiral effective theory. The correlator of topological charge densities at large momenta is calculated.Comment: 14 pages, 2 figure

    On the Flow of â–¡R\Box R Weyl-Anomaly

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    An important aspect of Weyl anomalies is that they encode information on the irreversibility of the renormalisation group flow. We consider, Δbˉ=bˉUV−bˉIR\Delta \bar b = \bar{b}^{\textrm{UV}} - \bar{b}^{\textrm{IR}}, the difference of the ultraviolet and infrared value of the □R\Box R-term of the Weyl anomaly. The quantity is related to the fourth moment of the trace of the energy momentum tensor correlator for theories which are conformal at both ends. Subtleties arise for non-conformal fixed points as might be the case for infrared fixed points with broken chiral symmetry. Provided that the moment converges, Δbˉ\Delta \bar{b} is then automatically positive by unitarity. Written as an integral over the renormalisation scale, flow-independence follows since its integrand is a total derivative. Furthermore, using a momentum subtraction scheme (MOM) the 4D Zamolodchikov- metric is shown to be strictly positive beyond perturbation theory and equivalent to the metric of a conformal manifold at both ends of the flow. In this scheme bˉ(μ)\bar{b}(\mu) can be extended outside the fixed point to a monotonically decreasing function. The ultraviolet finiteness of the fourth moment enables us to define a scheme for the δL∼b0R2\delta {\cal L} \sim b_0 R^2-term, for which the R2R^2-anomaly vanishes along the flow. In the MOM- and the R2R^2-scheme, bˉ(μ)\bar{b}(\mu) is shown to satisfy a gradient flow type equation. We verify our findings in free field theories, higher derivative theories and extend Δbˉ\Delta \bar{b} and the Euler flow Δβa\Delta \beta_a for a Caswell-Banks-Zaks fixed point for QCD-like theories to next-to-next-to leading order using a recent ⟨G2G2⟩\langle G^2G^2 \rangle-correlator computation.Comment: 28 pp + refs + 1 fig, v2 quasi identical to PRD-versio

    Chiral Estimates of Strong CP Violation Revisited

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    The effects of the CP violating θ\theta term in the QCD Lagrangian upon low energy hadronic phenomenology are reconsidered. Strong CP violating interactions among Goldstone bosons and octet baryons are incorporated into an effective chiral Lagrangian framework. The θ\theta term's impact upon the decays η→ππ\eta\to\pi\pi and π0→γγ\pi^0\to\gamma\gamma is then investigated but found to be extremely small. A refined model independent estimate of nonanalytic contributions to the neutron electric dipole moment is also determined using velocity dependent Baryon Chiral Perturbation Theory. We obtain the approximate upper bound ∣θ∣<4.5×10−10|\theta| < 4.5 \times 10^{-10}.Comment: 11 pages with 3 figures not included but available upon request, CALT-68-184

    On the CP-odd Nucleon Potential

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    The CP-odd nucleon potential for different models of CP violation in the one meson exchange approximation is studied. It is shown that the main contribution is due to the π\pi-meson exchange which leads to a simple one parameter CP-odd nucleon potential.Comment: 12 pages, RevTex, UM-P-92/114, OZ-92/3

    Potassium Channel and NKCC Cotransporter Involvement in Ocular Refractive Control Mechanisms

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    Myopia affects well over 30% of adult humans globally. However, the underlying physiological mechanism is little understood. This study tested the hypothesis that ocular growth and refractive compensation to optical defocus can be controlled by manipulation of potassium and chloride ion-driven transretinal fluid movements to the choroid. Chicks were raised with +/−10D or zero power optical defocus rendering the focal plane of the eye in front of, behind, or at the level of the retinal photoreceptors respectively. Intravitreal injections of barium chloride, a non-specific inhibitor of potassium channels in the retina and RPE or bumetanide, a selective inhibitor of the sodium-potassium-chloride cotransporter were made, targeting fluid control mechanisms. Comparison of refractive compensation to 5mM Ba2+ and 10−5 M bumetanide compared with control saline injected eyes shows significant change for both positive and negative lens defocus for Ba2+ but significant change only for negative lens defocus with bumetanide ; ; ; ; ; ). Vitreous chamber depths showed a main effect for drug conditions with less depth change in response to defocus shown for Ba2+ relative to Saline, while bumetanide injected eyes showed a trend to increased depth without a significant interaction with applied defocus. The results indicate that both K channels and the NKCC cotransporter play a role in refractive compensation with NKCC blockade showing far more specificity for negative, compared with positive, lens defocus. Probable sites of action relevant to refractive control include the apical retinal pigment epithelium membrane and the photoreceptor/ON bipolar synapse. The similarities between the biometric effects of NKCC inhibition and biometric reports of the blockade of the retinal ON response, suggest a possible common mechanism. The selective inhibition of refractive compensation to negative lens in chick by loop diuretics such as bumetanide suggests that these drugs may be effective in the therapeutic management of human myopia
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