22,127 research outputs found

    Universality of Mixed Action Extrapolation Formulae

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    Mixed action theories with chirally symmetric valence fermions exhibit very desirable features both at the level of the lattice calculations as well as in the construction and implementation of the low energy mixed action effective field theory. In this work we show that when such a mixed action effective field theory is projected onto the valence sector, both the Lagrangian and the extrapolation formulae become universal in form through next to leading order, for all variants of discretization methods used for the sea fermions. Our conclusion relies on the chiral nature of the valence quarks. The result implies that for all sea quark methods which are in the same universality class as QCD, the numerical values of the physical coefficients in the various mixed action chiral Lagrangians will be the same up to lattice spacing dependent corrections. This allows us to construct a prescription to determine the mixed action extrapolation formulae for a large class of hadronic correlation functions computed in partially quenched chiral perturbation theory at the one-loop level. For specific examples, we apply this prescription to the nucleon twist--2 matrix elements and the nucleon--nucleon system. In addition, we determine the mixed action extrapolation formula for the neutron EDM as this provides a nice example of a theta-dependent observable; these observables are exceptions to our prescription.Comment: 36 pages, appendix on twisted mass sea fermions added, expanded discussion of NLO operators, version published in JHEP; typographical errors corrected in Eqs. (68) and (69

    Dynamics of Low-Density Ultracold Rydberg Gases

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    Population dynamics in weakly-excited clouds of ultracold 87^{87}Rb Rydberg atoms were studied by means of trap loss, fluorescence detection, and state dependent stimulated emission. Rydberg atoms were excited to various nl Rydberg states via continuous two-photon excitation from a magneto-optical trap. A stimulated emission probe laser was then used to bring the Rydberg atoms down to the 6P3/2_{3/2} state, allowing state-dependent detection of the Rydberg atoms. Measurements of trap loss and fluorescent emission reveal information about the evolution of the Rydberg populations. In particular, population in the initial Rydberg state quickly transfers to other Rydberg states by a non-collisional mechanism, likely superradiant emission. The trap-loss measurements are consistent with black-body ionization as the dominant loss mechanism.Comment: 9 pages, 7 figure

    The distance to the LMC cluster NGC 1866 and the surrounding field

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    We use the Main Sequence stars in the LMC cluster NGC 1866 and of Red Clump stars in the local field to obtain two independent estimates of the LMC distance. We apply an empirical Main Sequence-fitting technique based on a large sample of subdwarfs with accurate {\sl Hipparcos} parallaxes in order to estimate the cluster distance modulus, and the multicolor Red Clump method to derive distance and reddening of the LMC field. We find that the Main Sequence-fitting and the Red Clump distance moduli are in significant disagreement; NGC 1866 distance is equal to (m−M)0,NGC1866=18.33±\rm (m-M)_{0,NGC 1866}=18.33\pm0.08 (consistent with a previous estimate using the same data and theoretical Main Sequence isochrones), while the field stars provide (m−M)0,field=18.53±\rm (m-M)_{0,field}=18.53\pm0.07. This difference reflects the more general dichotomy in the LMC distance estimates found in the literature. Various possible causes for this disagreement are explored, with particular attention paid to the still uncertain metallicity of the cluster and the star formation history of the field stars.Comment: 5 pages, incl. 1 figure, uses emulateapj.sty, ApJ accepte

    Design of Pre-Dumping Ring Spin Rotator with a Possibility of Helicity Switching for Polarized Positrons at the ILC

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    The use of polarized beams enhance the possibility of the precision measurements at the International Linear Collider (ILC). In order to preserve the degree of polarization during beam transport spin rotators are included in the current TDR ILC Lattice. In this report some advantages of using a combined spin rotator/spin flipper are discussed. A few possible lattice designs of spin flipper developed at DESY in 2012 are presented.Comment: Talk presented at the International Workshop on Future Linear Colliders (LCWS15), Whistler, Canada, 2-6 November 201

    Extending the paramedic role in rural Australia : a story of flexibility and innovation

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    Introduction: This article identifies trends in the evolving practice of rural paramedics and describes key characteristics, roles and expected outcomes for a Rural Expanded Scope of Practice (RESP) model.Methods: A multiple case study methodology was employed to examine the evolution of rural paramedic practice. Paramedics, volunteer ambulance officers and other health professionals were interviewed in four rural regions of south-eastern Australia where innovative models of rural paramedic practice were claimed to exist. The research team collected and thematically analysed the data using the filter of a sociological framework throughout 2005 and 2006.Results: The study found that paramedics are increasingly becoming first line primary healthcare providers in small rural communities and developing additional professional responsibilities throughout the cycle of care.Conclusions: Adoption of the RESP model would mean that paramedics undertake four broad activities as core components of their new role: (1) rural community engagement; (2) emergency response; (3) situated practice; and (4) primary health care. The model&rsquo;s key feature is a capacity to integrate existing paramedic models with other health agencies and health professionals to ensure that paramedic care is part of a seamless system that provides patients with well-organized and high quality care. This expansion of paramedics&rsquo; scope of practice offers the potential to improve patient care and the general health of rural communities.<br /

    A database of ocean primary productivity from the 14C method

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    The database on ocean primary productivity comprises over two decades (1985–2008) of data that the authors have participated in collecting, using the assimilation of inorganic 14C through photosynthesis, in incubations carried out in situ. The dataset is perhaps unique in that it uses, overwhelmingly, consistent methodology while covering a wide geographic range. Ancillary data are included. Using the database, it is hoped that investigators can test for the relationships among the environmental drivers for ocean productivity, the meaning of the 14C method in terms of phytoplankton physiology and the dynamics in the water column, and as a resource for further development of productivity algorithms using satellite ocean color imagery

    Investigating Ca II emission in the RS CVn binary ER Vulpeculae using the Broadening Function Formalism

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    The synchronously rotating G stars in the detached, short-period (0.7 d), partially eclipsing binary, ER Vul, are the most chromospherically active solar-type stars known. We have monitored activity in the Ca II H & K reversals for almost an entire orbit. Rucinski's Broadening Function Formalism allows the photospheric contribution to be objectively subtracted from the highly blended spectra. The power of the BF technique is also demonstrated by the good agreement of radial velocities with those measured by others from less crowded spectral regions. In addition to strong Ca II emission from the primary and secondary, there appears to be a high-velocity stream flowing onto the secondary where it stimulates a large active region on the surface 30 - 40 degrees in advance of the sub-binary longitude. A model light curve with a spot centered on the same longitude also gives the best fit to the observed light curve. A flare with approximately 13% more power than at other phases was detected in one spectrum. We suggest ER Vul may offer a magnified view of the more subtle chromospheric effects synchronized to planetary revolution seen in certain `51 Peg'-type systems.Comment: Accepted to AJ; 17 pages and 16 figure

    Coherent versus Incoherent Light Scattering from a Quantum Dot

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    We analyze the light scattered by a single InAs quantum dot interacting with a resonant continuous-wave laser. High resolution spectra reveal clear distinctions between coherent and incoherent scattering, with the laser intensity spanning over four orders of magnitude. We find that the fraction of coherently scattered photons can approach unity under sufficiently weak or detuned excitation, ruling out pure dephasing as a relevant decoherence mechanism. We show how spectral diffusion shapes spectra, correlation functions, and phase-coherence, concealing the ideal radiatively-broadened two-level system described by Mollow.Comment: to appear in PRB 85, 23531

    Exercise training for chronic heart failure (ExTraMATCH II): individual participant data meta-analysis of randomised controlled trials

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    This is the author accepted manuscript. The final version is available from NIHR Journals Library via the DOI in this record.Background: Current national and international guidelines on the management of heart failure (HF) recommend exercise-based cardiac rehabilitation (ExCR), but do not differentiate this recommendation according to patient subgroups. Objective(s): (1) to obtain definitive estimates of the impact of ExCR interventions versus control (no exercise intervention) on mortality, hospitalisation, exercise capacity, and health-related quality of life (HRQoL) in HF patients; (2) to determine the differential (subgroup) effects of ExCR in HF patients according to their age, gender, ejection fraction, aetiology, New York Heart Association (NYHA) class, and baseline exercise capacity; (3) to assess whether the change in exercise capacity mediates for the impact of the ExCR on final outcomes (mortality, hospitalisation, and HRQoL) and is an acceptable surrogate endpoint. Design: Individual participant data (IPD) meta-analysis Setting: An international literature review Participants: HF patients in randomised controlled trials (RCTs) of ExCR Interventions: ExCR for at least 3 weeks compared with no exercise control with 6 months follow-up Main outcome measures: mortality (all cause and HF-specific), hospitalisation (all-cause & HF-specific), exercise capacity, and HRQoL Data sources: Individual participant data from eligible RCTs 3 Review methods: RCTs from ExTraMATCH IPD meta-analysis and 2014 Cochrane systematic review of ExCR Results: Out of the 23 eligible RCTs (4,398 patients), 19 RCTs (3,990 patients) contributed data to this IPD meta-analysis. There was a wide variation in exercise programme prescriptions across included studies. Compared with control, there was no statistically significant difference in pooled time to event estimates in favour of ExCR although confidence intervals were wide: all-cause mortality: hazard ratio (HR) 0.83 (95% confidence interval (CI): 0.67 to 1.04), HF-related mortality: HR 0.84 (95% CI: 0.49 to 1.46), all-cause hospitalisation: HR 0.90 (95% CI: 0.76 to 1.06), and HF-related hospitalisation: HR 0.98 (95% CI: 0.72 to 1.35). There was a statistically significant difference in favour of ExCR for exercise capacity and HRQoL. Compared to control, at 12-months follow-up, improvements were seen in the six-minute walk test (6MWT) (mean: 21.0 metres, 95% CI: 1.57 to 40.4, and Minnesota Living with HF Questionnaire score (mean: -5.94, 95% CI: -1.0 to -10.9, lower scores indicate improved HRQoL). No strong evidence for differential intervention effects across patient characteristics was found for any outcomes. Moderate to good levels of correlation (R2 trial>50% & ρ>0.50) between peak oxygen uptake (VO2peak) or 6MWT with mortality and HRQoL were seen. Estimated surrogate threshold effect (STE) was an increase of 1.6 to 4.6 ml/kg/min for VO2peak. Limitations: Lack consistency in how included RCTs defined and collected the outcomes; we were unable to obtain IPD from all includable trials for all outcomes; and we did not seek patient level on exercise adherence. . Conclusions: In comparison to no exercise control, participation in ExCR improves the exercise and HRQoL in HF patients but appears to have no effect on their mortality or hospitalisation. No strong evidence was found of differential intervention effects of ExCR across patient characteristics. VO2peak and 6MWT may be suitable surrogate endpoints for the treatment effect of ExCR on mortality and HRQoL in HF.NIHR Health Technology Assessment programm
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