An observational test of common-envelope evolution

By analysing and modelling the change in the abundance ratio of $^{12}$C/$^{13}$C and $^{16}$O/$^{17}$O on the surface of the lower mass star of a binary during the common-envelope (CE) phase of evolution, we propose a simple observational test of the CE scenario. The test is based on the infrared measurement of either the $^{12}$C/$^{13}$C or $^{16}$O/$^{17}$O ratio of red dwarfs in post-common envelope binaries (PCEB's). In certain cases (main-sequence red dwarf secondaries in PCEB's without planetary nebulae), as well as determining whether or not accretion has occurred during the CE phase, we can determine the amount of mass accreted during the CE phase and hence the initial mass of the red dwarf component prior to the CE phase. In the other cases considered (low-mass red dwarfs in PCEB's and red dwarf's in PCEB's with planetary nebulae) we can only say whether or not accretion has occurred during the CE phase.Comment: uuencoded compressed postscript. The preprint are also available at URL http://www.ast.cam.ac.uk/preprint/PrePrint.htm

From the Heart of The Ghoul: C and N Abundances in the Corona of Algol B

Chandra Low Energy Transmission Grating Spectrograph observations of Algol have been used to determine the abundances of C and N in the secondary star for the first time. The analysis was performed relative to similar observations of an adopted "standard" star HR 1099. It is demonstrated that HR 1099 and Algol are coronal twins in many respects and that their X-ray spectra are very similar in nearly all details, except for the observed strengths of C and N lines. The H-like transitions of C and N in the coronae of Algol and HR 1099 demonstrate that the surface abundances of Algol B have been strongly modified by CN-processing, as shown earlier by Schmitt & Ness (2002). It is found that N is enhanced in Algol B by a factor of 3 compared to HR 1099. No C lines are detected in the Algol spectrum, indicating a C depletion relative to HR 1099 by a factor of 10 or more. These C and N abundances indicate that Algol B must have lost at least half of its initial mass, and are consistent with predictions of evolutionary models that include non-conservative mass transfer and angular momentum loss through magnetic activity. Little or no dredge-up of material subjected to CN-processing has occurred on the subgiant component of HR 1099. It is concluded that Fe is very likely depleted in the coronae of both Algol and HR 1099 relative to their photospheres by 0.5 dex, and C, N and O by 0.3 dex. Instead, Ne is enhanced by up to 0.5 dex.Comment: 17 pages, 4 figures, ApJ accepte

Grad’s Moment Equations for Binary Hard Sphere Gas-Mixtures

This paper was presented at the 4th Micro and Nano Flows Conference (MNF2014), which was held at University College, London, UK. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute, ASME Press, LCN London Centre for Nanotechnology, UCL University College London, UCL Engineering, the International NanoScience Community, www.nanopaprika.eu.The derivation of non-linear Grad’s 2×26-moment (2×G26) equations for a binary gasmixture of monatomic-inert-ideal hard sphere gases is sketched, although—for conciseness—only the linear 2×G26 equations are illustrated and analysed. The linear stability analysis is performed on 2×G26 equations by studying the dispersion relation and by considering the plane wave solution, it is shown that the 2×G26 equations for binary hard sphere gas-mixture are linearly stable

X-ray Evidence of the Common Envelope Phase of V471 Tauri

Chandra Low Energy Transmission Grating Spectrograph observations of the pre-cataclysmic binary V471 Tau have been used to estimate the C/N abundance ratio of the K dwarf component for the first time. While the white dwarf component dominates the spectrum longward of 50 AA, at shorter wavelengths the observed X-ray emission is entirely due to coronal emission from the K dwarf. The H-like resonance lines of C and N yield an estimate of their logarithmic abundance ratio relative to the Sun of [C/N]=-0.38+/-0.15 - half of the currently accepted solar value. We interpret this result as the first clear observational evidence for the presumed common envelope phase of this system, during which the surface of the K dwarf was contaminated by CN-cycle processed material dredged up into the red giant envelope. We use the measured C/N ratio to deduce that 0.015-0.04 Msun was accreted by the K dwarf while engulfed, and show that this is consistent with a recent tentative detection of 13C in the K dwarf photosphere, and with the measured Li abundance in the scenario where the red giant companion was Li-rich during the common envelope phase.Comment: 6 pages, 2 figures, ApJL accepte

Efficacy of Multi-Modal Migraine Prophylaxis Therapy on Hyperacusis Patients.

ObjectivesTo evaluate the efficacy of a multi-modal migraine prophylaxis therapy for patients with hyperacusis.MethodsIn a prospective cohort, patients with hyperacusis were treated with a multi-modal step-wise migraine prophylactic regimen (nortriptyline, verapamil, topiramate, or a combination thereof) as well as lifestyle and dietary modifications. Pre- and post-treatment average loudness discomfort level (LDL), hyperacusis discomfort level measured by a visual analogue scale (VAS), and scores on the modified Khalfa questionnaire for severity of hyperacusis were compared.ResultsTwenty-two of the 25 patients (88%) reported subjective resolution of their symptoms following treatment. Post-treatment audiograms showed significant improvement in average LDL from 81.3 ± 3.2 dB to 86.4 ± 2.6 dB (P < .001), indicating increased sound tolerability. The VAS discomfort level also showed significant improvement from a pre-treatment average of 7.7 ± 1.1 to 3.7 ± 1.6 post-treatment (P < .001). There was also significant improvement in the average total score on modified Khalfa questionnaire (32.2 ± 3.6 vs 22.0 ± 5.7, P < .001).ConclusionsThe majority of patients with hyperacusis demonstrated symptomatic improvement from migraine prophylaxis therapy, as indicated by self-reported and audiometric measures. Our findings indicate that, for some patients, hyperacusis may share a pathophysiologic basis with migraine disorder and may be successfully managed with multimodal migraine prophylaxis therapy

Hydrodynamic simulations of irradiated secondaries in dwarf novae

We investigate numerically the surface flow on the secondary star during outbursts. We use a simple model for the irradiation and the geometry of the secondary star: the irradiation temperature is treated as a free parameter and the secondary is replaced by a spherical star with a space-dependent Coriolis force that mimics the effect of the Roche geometry. The Euler equations are solved in spherical coordinates with the TVD-MacCormack scheme. We show that the Coriolis force leads to the formation of a circulation flow from high latitude region to the close vicinity of the $L_1$ point. However no heat can be efficiently transported to the $L_1$ region due to the rapid radiative cooling of the hot material as it enters the equatorial belt shadowed from irradiation. Under the assumption of hydrostatic equilibrium, the Coriolis force could lead to a moderate increase of the mass transfer rate by pushing the gas in the vertical direction at the $L_1$ point, but only during the initial phases of the outburst (about 15 -- 20 orbital periods). We conclude that the Coriolis force does not prevent a flow from the heated regions of the secondary towards the $L_1$ region, at least during the initial phase of an outburst, but the resulting increase of the mass transfer rate is moderate, and it is unlikely to be able to account for the duration of long outbursts.Comment: 11 pages, 11 figures, accepted for publication in A&

The Discovery of a Companion to the Lowest Mass White Dwarf

We report the detection of a radial velocity companion to SDSS J091709.55+463821.8, the lowest mass white dwarf currently known with M~0.17Msun. The radial velocity of the white dwarf shows variations with a semi-amplitude of 148.8 km/s and a period of 7.5936 hours, which implies a companion mass of M > 0.28Msun. The lack of evidence of a companion in the optical photometry forces any main-sequence companion to be smaller than 0.1Msun, hence a low mass main sequence star companion is ruled out for this system. The companion is most likely another white dwarf, and we present tentative evidence for an evolutionary scenario which could have produced it. However, a neutron star companion cannot be ruled out and follow-up radio observations are required to search for a pulsar companion.Comment: ApJ, in press. See the Press Release at http://www.cfa.harvard.edu/press/2007/pr200708.htm

Mortality and health-related habits in 900 Finnish former elite athletes and their brothers

Background There is conflicting evidence on the associations between participation in vigorous sports, health habits, familial factors and subsequent mortality. We investigated all-cause mortality and health-related behaviour among former elite athletes and their brothers. Methods The mortality of Finnish male former elite athletes, who had represented Finland between 1920 and 1965 (n=900) and their age-matched brothers (n=900), was followed from the time when athlete started an elite athlete career until 31 December 2015. The age-adjusted HRs were calculated by a paired Cox proportional hazards model. In 2001, surviving participants (n=199 athletes and n=199 age-matched brothers) reported their self-rated health (SRH), physical activity, alcohol consumption and smoking habits in the questionnaire. Results During the total follow-up period, 1296 deaths (72% of the cohort) occurred. The age-adjusted HRs for all-cause mortality in former athletes was 0.75 (95% CI 0.65 to 0.87, P Conclusions Former elite athletes are more physically active, smoke less, have better self-rated health and live longer than their brothers. Genetic differences between athletes and brothers, aerobic training for endurance elite sports and a healthier lifestyle may all contribute to reduced mortality.Peer reviewe

Near-Infrared Light Curves of the Black Hole Binary A0620-00

We measured the near-infrared orbital light curve of the black hole binary A0620-00 in 1995 and 1996. The light curves show an asymmetric, double-humped modulation with extra emission in the peak at orbital phase 0.75. There were no significant changes in the shape of the light curve over the one-year observation period. There were no sharp dips in the light curves nor reversals of the asymmetry between the two peaks as seen in earlier observations. The light curves are well fit by models incorporating ellipsoidal variations from the mass-losing K-type star plus a beamed bright spot on the accretion disk around the compact star. The long-term stability of the light curve shape rules out superhumps and star spots as sources of asymmetry when we observed A0620-00. The ellipsoidal variations yield a lower limit i >= 38 deg on the orbital inclination. The light curves show no eclipse features, which places an upper limit i <= 75 deg. This range of inclinations constrains the mass of the compact object to 3.3 < M_1 < 13.6 Msun. The light curves do not further constrain the orbital inclination because the contribution of the accretion disk to the observed flux is unknown. We argue that a previous attempt to measure the near-infrared flux from the accretion disk using the dilution of the 12CO(2,0) bandhead in the spectrum of the K star is not reliable because the band strength depends strongly on surface gravity.Comment: Accepted for publication in the Astronomical Journal. 17 pages, 4 figures. Prepared using AASTEX V. 5.

Severe diarrhoea caused by highly ciprofloxacin-susceptible Campylobacter isolates

AbstractThe impact of fluoroquinolone resistance of Campylobacter jejuni and Campylobacter coli isolates on the outcome of the disease in sporadic Campylobacter infections of Finnish individuals was studied. Questionnaires were sent, during a 6-month study period, to patients who were stool culture-positive for Campylobacter spp. In total, 192 returned questionnaires were analysed and assessed, together with the susceptibility data of the respective bacterial isolates. Only one (2%) of the domestic, but half of the imported, Campylobacter isolates were resistant to ciprofloxacin. Ciprofloxacin resistance was not associated with particularly severe infection. Instead, ciprofloxacin-susceptible Campylobacter isolates, as compared to ciprofloxacin-resistant isolates, showed a tendency to cause more severe infections, characterized by bloody stools and hospitalization