729 research outputs found

    Can the British Heart Foundation PocketCPR Application Improve the Performance of Chest Compressions During Bystander Resuscitation: a Randomised Crossover Manikin Study

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    This study aims to determine whether the British Heart Foundation (BHF) PocketCPR application can improve the depth and rate of chest compression, and therefore be confidently recommended for bystander use. 118 candidates were recruited into a randomised crossover manikin trial. Each candidate performed CPR for two-minutes without instruction, or performed chest compressions using the PocketCPR application. Candidates then performed a further two minutes of CPR within the opposite arm. The number of chest compressions performed improved when PocketCPR was used compared to chest compressions when it was not (44.28% v40.57, P<0.001). The number of chest compressions performed to the required depth was higher in the PocketCPR group (90.86 v 66.26). The BHF PocketCPR application improved the percentage of chest compressions that were performed to the required depth. Despite this, more work is required in order to develop a feedback device that can improve bystander CPR without creating delay

    Orbits and Pulsations of the Classical ζ Aurigae Binaries

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    We have derived new orbits for ζ Aur, 32 Cyg, and 31 Cyg with observations from the Tennessee State University (TSU) Automatic Spectroscopic Telescope, and used them to identify nonorbital velocities of the cool supergiant components of these systems. We measure periods in those deviations, identify unexpected long-period changes in the radial velocities, and place upper limits on the rotation of these stars. These radial-velocity variations are not obviously consistent with radial pulsation theory, given what we know about the masses and sizes of the components. Our concurrent photometry detected the nonradial pulsations driven by tides (ellipsoidal variation) in both ζ Aur and 32 Cyg, at a level and phasing roughly consistent with simple theory to first order, although they seem to require moderately large gravity darkening. However, the K component of 32 Cyg must be considerably bigger than expected, or have larger gravity darkening than ζ Aur, to fit its amplitude. However, again there is precious little evidence for the normal radial pulsation of cool stars in our photometry. Hα shows some evidence for chromospheric heating by the B component in both ζ Aur and 32 Cyg, and the three stars show among them a meager ~2-3 outbursts in their winds of the sort seen occasionally in cool supergiants. We point out two fundamental questions in the interpretation of these stars: (1) whether it is appropriate to model the surface brightness as gravity darkening and (2) whether much of the nonorbital velocity structure may actually represent changes in the convective flows in the stars\u27 atmospheres

    Assessing Continuous Contamination Discharge from a Combined Sewer Outfall (CSO) into a Tidal Wetland Creek: Bacteriological and Heavy Metals Indicators

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    Continuous discharge from a combined sewer overflow (CSO) into a tidal wetland creek in the New York City urban area was analyzed to assess the extent of water quality degradation from fecal bacteria contamination during both dry and wet weather. A combination of fecal indicator bacteria (FIB), total suspended solids, and dissolved metals were used to infer the presence of sewage pollution from the CSO discharge and to constrain the spatial and temporal impact on water quality and dry season creek flows. Upstream of the CSO, creek flow was dominated by groundwater input, and FIB levels were very low or undetected, indicating the absence of contamination. Low-volume loading was detected in dry weather, in contrast to the expected impact when a CSO is operating as designed (flowing only following wet weather). In wet weather, a “first flush” peak was detected for some contaminants, followed by diluted contaminant concentrations due to to increased flow volume but resulting in greater total loading that affected a larger area. The correlation of bacteriological and metal indicators in paired spatial and temporal samples revealed a positive relationship between the concentration of some metals (e.g Na, Fe) and FIB. Variable patterns of peak metal concentration in the creek, with respect to precipitation and FIB level, also suggest changes in contaminant source and the influence of tidal backwater

    Random Spots on Chromospherically Active Stars

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    We have investigated the effect of large numbers of moderately sized spots placed randomly on a differentially rotating star as the explanation of the rotational light curves of magnetically active cool stars. This hypothesis produces light variation very similar to observed light curves of RS CVn binaries, provided there are of order 10-40 spots at any time and provided individual spots have a finite lifetime

    SPOT on RS CVn From Spectroscopy and Photometry

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    We have used contemporaneous spectra and V light curves to form spot models for RS CVn in 1991 and 1992. More than two spots are needed to fit all the properties of the observations. In fact, moderately small spots (22 x 28 deg in latitude and longitude) having only a slight effect on the rotational light curve were eclipsed in both years, and we find that a collection of 6-8 such moderate spots is required to fit the line profiles in each year. These groups of spots also account naturally for a difference in level of light between the two years. There is no evidence for polar spots larger than 18 degrees in radius. We have also derived new orbits from radial velocities of the stars, which give the mass ratio Mc/Mh = 1.04 +/-0.02

    The Rotation Period of the Planet-Hosting Star HD 189733

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    We present synoptic optical photometry of HD 189733, the chromospherically active parent star of one of the most intensively studied exoplanets. We have significantly extended the timespan of our previously reported observations and refined the estimate of the stellar rotation period by more than an order of magnitude: P=11.953±0.009P = 11.953\pm 0.009 days. We derive a lower limit on the inclination of the stellar rotation axis of 56\arcdeg (with 95% confidence), corroborating earlier evidence that the stellar spin axis and planetary orbital axis are well aligned.Comment: To appear in A

    A Super-Earth Orbiting the Nearby Sun-like Star HD 1461

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    We present precision radial velocity data that reveal a Super-Earth mass planet and two probable additional planets orbiting the bright nearby G0V star HD 1461. Our 12.8 years of Keck HIRES precision radial velocities indicate the presence of a 7.4M_Earth planet on a 5.77-day orbit. The data also suggest, but cannot yet confirm, the presence of outer planets on low-eccentricity orbits with periods of 446.1 and 5017 days, and projected masses (M sin i) of 27.9 and 87.1M_Earth, respectively. Test integrations of systems consistent with the radial velocity data suggest that the configuration is dynamically stable. We present a 12.2-year time series of photometric observations of HD 1461, which comprise 799 individual measurements, and indicate that it has excellent long-term photometric stability. However, there are small amplitude variations with periods comparable to those of the suspected 2nd and 3rd signals in the radial velocities near 5000 and 446 days, thus casting some suspicion on those periodicities as Keplerian signals. If the 5.77-day companion has a Neptune-like composition, then its expected transit depth is of order ~0.5 millimags. The geometric a priori probability of transits is ~8%. Phase-folding of the ground-based photometry shows no indication that transits of the 5.77-day companion are occurring, but high-precision follow-up of HD 1461 during upcoming transit phase windows will be required to definitively rule out or confirm transits. This new system joins a growing list of solar-type stars in the immediate galactic neighborhood that are accompanied by at least one Neptune- (or lower) mass planets having orbital periods of 50 days or less.Comment: 33 pages, 7 figure

    Chromospherically Active Stars. XXI. The Giant, Single-lined Binaries HD 89546 And HD 113816

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    We have obtained spectroscopy and photometry of the chromospherically active, single-lined spectroscopic binaries HD 89546 and HD 113816. HD 89546 has a circular orbit with a period of 21.3596 days. Its primary has a spectral type of G9 III and is somewhat metal-poor with [Fe/H]~-0.5. HD 113816 has an orbit with a period of 23.6546 and a low eccentricity of 0.022. Its mass function is extremely small, 0.0007 Msolar, consistent with a very low inclination. The primary is a slightly metal-poor K2 III. A decade or more of photometric monitoring with an automatic telescope demonstrates that both systems display brightness variations due to rotational modulation of the visibility of photospheric star spots, as well as light-curve changes resulting from the redistribution of star spots by differential rotation and long-term changes in the filling factor of the spots. We determined rotation periods for each season when the observations were numerous enough. Our mean rotation periods of 21.3 and 24.1 days for HD 89546 and HD 113816, respectively, confirm that the giants in each system are synchronously rotating. The orbital elements and properties of the giant components of these two systems, including levels of surface magnetic activity, are quite similar. However, the two rotational inclinations are rather different, 57° for HD 89546 and 13° for HD 113816. Thus the latter giant is seen nearly pole on. We analyzed the light curves for similarities and differences that result from viewing these two systems from quite different inclinations
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