Periodic Modulations in an X-ray Flare from Sagittarius A*

We present the highly significant detection of a quasi-periodic flux modulation with a period of 22.2 min seen in the X-ray data of the Sgr A* flare of 2004 August 31. This flaring event, which lasted a total of about three hours, was detected simultaneously by EPIC on XMM-Newton and the NICMOS near-infrared camera on the HST. Given the inherent difficulty in, and the lack of readily available methods for quantifying the probability of a periodic signal detected over only several cycles in a data set where red noise can be important, we developed a general method for quantifying the likelihood that such a modulation is indeed intrinsic to the source and does not arise from background fluctuations. We here describe this Monte Carlo based method, and discuss the results obtained by its application to a other XMM-Newton data sets. Under the simplest hypothesis that we witnessed a transient event that evolved, peaked and decayed near the marginally stable orbit of the supermassive black hole, this result implies that for a mass of 3.5 x 10^{6} Msun, the central object must have an angular momentum corresponding to a spin parameter of a=0.22.Comment: 4 pages, 6 figures, submitted to ApJ

The Inhomogeneous Wind of the LBV Candidate CygOB2-No.12

We present the results of high-resolution spectroscopy of the extremely luminous star CygOB2-No.12. We identified about 200 spectral features in the range 4552-7939 AA, including the interstellar NaI, KI lines and numerous very strong DIBs, along with the HeI, CII, and SiII lines. An MK spectral type we derived for the object is B4.5Ia+. Our analysis of the radial velocity data shows the presence of a gradient in the stellar atmosphere, caused by both atmospheric expansion and matter infall onto the star. The Halpha emission displays broad Thompson wings, a slightly blue-shifted PCyg type absorption component and a time-variable core absorption. We conclude that the wind is variable in time.Comment: 3 pages, 2 figures, IAU Symposium No.272 "Active OB stars: structure, evolution, mass loss and critical limits", 201

Die betroubaarheid en faktorstruktuur van die aangepaste meervoudige keuse-formaat van die miner sentence completion scale (MSCS)

The original publication is available at http://www.sajip.co.zaThe reliability and factor structure of the adapted multiple choice version of the Miner Sentence Completion Scale (MSCS). In this study the multiple choice MSCS was adapted as a result of several criticisms thereof. The internal consistency and factor structure of the adapted MSCS were determined to ascertain the reliability and construct validity of the questionnaire. Results show that the internal consistency is unsatisfactory and that the factor structure is so complex that interpretation becomes virtually impossible. In light of the results of this study and other research findings of the psychometric properties of the MSCS, it is recommended that a new measuring instrument for managerial motivation be developed that will enable a valid testing of the managerial rolemotivation theory.Na aanleiding van verskeie punte van kritiek teen die MSCS is die meervoudige keuse-MSCS in hierdie studie aangepas. Ten einde 'n aanduiding van die betroubaarheid en konstrukgeldigheid van die aangepaste MSCS te verkry, is die interne konsekwentheid en faktorstruktuur daarvan bepaal. Die resultate dui daarop dat die interne konsekwentheid onbevredigend en die faktorstruktuur te kompleks vir interpretasie is. In die lig van die bevindinge van hierdie studie, en ander navorsingsbevindinge oor die psigometriese eienskappe van die MSCS, word aanbeveel dat 'n nuwe meetinstrument van bestuursmotivering ontwikkel word wat 'n geldige toetsing van die bestuursrol-motiveringsteorie moontlik sal maak.Publishers' Versio

X-Ray Evidence for Flare Density Variations and Continual Chromospheric Evaporation in Proxima Centauri

Using the XMM-Newton X-ray observatory to monitor the nearest star to the Sun, Proxima Centauri, we recorded the weakest X-ray flares on a magnetically active star ever observed. Correlated X-ray and optical variability provide strong support for coronal energy and mass supply by a nearly continuous sequence of rapid explosive energy releases. Variable emission line fluxes were observed in the He-like triplets of OVII and NeIX during a giant flare. They give direct X-ray evidence for density variations, implying densities between 2x10^{10} - 4x10^{11} cm^{-3} and providing estimates of the mass and the volume of the line-emitting plasma. We discuss the data in the context of the chromospheric evaporation scenario.Comment: 10 pages, 2 figures, accepted by The Astrophysical Journal, Letters; improved calculations of radiative loss of cool plasma (toward end of paper

A Spectacular VHE Gamma-Ray Outburst from PKS 2155-304 in 2006

Since 2002 the VHE (>100 GeV) gamma-ray flux of the high-frequency peaked BL Lac PKS 2155-304 has been monitored with the High Energy Stereoscopic System (HESS). An extreme gamma-ray outburst was detected in the early hours of July 28, 2006 (MJD 53944). The average flux above 200 GeV observed during this outburst is ~7 times the flux observed from the Crab Nebula above the same threshold. Peak fluxes are measured with one-minute time scale resolution at more than twice this average value. Variability is seen up to ~600 s in the Fourier power spectrum, and well-resolved bursts varying on time scales of ~200 seconds are observed. There are no strong indications for spectral variability within the data. Assuming the emission region has a size comparable to the Schwarzschild radius of a ~10^9 solar mass black hole, Doppler factors greater than 100 are required to accommodate the observed variability time scales.Comment: 4 pages, 3 figures; To appear in the Proceedings of the 30th ICRC (Merida, Mexico

Collisionless Damping of Fast MHD Waves in Magneto-rotational Winds

We propose collisionless damping of fast MHD waves as an important mechanism for the heating and acceleration of winds from rotating stars. Stellar rotation causes magnetic field lines anchored at the surface to form a spiral pattern and magneto-rotational winds can be driven. If the structure is a magnetically dominated, fast MHD waves generated at the surface can propagate almost radially outward and cross the field lines. The propagating waves undergo collisionless damping owing to interactions with particles surfing on magnetic mirrors that are formed by the waves themselves. The damping is especially effective where the angle between the wave propagation and the field lines becomes moderately large ($\sim 20$ to $80^{\circ}$). The angle tends naturally to increase into this range because the field in magneto-rotational winds develops an increasingly large azimuthal component. The dissipation of the wave energy produces heating and acceleration of the outflow. We show using specified wind structures that this damping process can be important in both solar-type stars and massive stars that have moderately large rotation rates. This mechanism can play a role in coronae of young solar-type stars which are rapidly rotating and show X-ray luminosities much larger than the sun. The mechanism could also be important for producing the extended X-ray emitting regions inferred to exist in massive stars of spectral type middle B and later.Comment: 12 pages, including 7 figures, accepted for publication in Ap

The role of functional health literacy in long-term treatment outcomes in psychosocial care for adolescents

Although among adolescents with psychosocial problems low health literacy may increase the risk of poor treatment outcomes, the contributing mechanisms within treatment remain unclear. A better understanding of these mechanisms could contribute to improved treatment processes and outcomes. This study aims to examine the relationship between functional health literacy, treatment processes (treatment adherence, learning processes), and treatment outcome (level of psychosocial problems) in adolescents in psychosocial care. We used data from a prospective cohort study among adolescents aged 12-18 (N = 390), collected in four successive measurements: at entry into care, and 3, 12, and 24 months thereafter. We used a mixed effect model to investigate the association between level of functional health literacy (adequate vs. inadequate) and treatment processes (treatment adherence, learning processes) and treatment outcome (level of psychosocial problems). Between adolescents with adequate and inadequate functional health literacy, we found no differences or change over time in adherence or learning processes. The level of psychosocial problems significantly declined over time (β = - 1.70, 95% CI [- 2.72, - 0.69], p = .001) to a similar degree in both groups, though, in all measurements, the level was consistently higher for adolescents with inadequate health literacy. We conclude that health literacy levels did not affect change in treatment processes nor in outcomes of psychosocial treatment. However, the consistently higher level of psychosocial problems among adolescents with inadequate health literacy suggests an unaddressed need in psychosocial care

Ergogenic effect of pre-exercise chicken broth ingestion on a high-intensity cycling time-trial

Background: chicken meat extract is a popular functional food in Asia. It is rich in the bioactive compounds carnosine and anserine, two histidine-containing dipeptides (HCD). Studies suggest that acute pre-exercise ingestion of chicken extracts has important applications towards exercise performance and fatigue control, but the evidence is equivocal. This study aimed to evaluate the ergogenic potential of the pre-exercise ingestion of a homemade chicken broth (CB) vs a placebo soup on a short-lasting, high-intensity cycling exercise. Methods: fourteen men participated in this double-blind, placebo-controlled, crossover intervention study. Subjects ingested either CB, thereby receiving 46.4 mg/kg body weight of HCD, or a placebo soup (similar in taste without HCD) 40 min before an 8 min cycling time trial (TT) was performed. Venous blood samples were collected at arrival (fasted), before exercise and at 5 min recovery. Plasma HCD were measured with UPLC-MS/MS and glutathione (in red blood cells) was measured through HPLC. Capillary blood samples were collected at different timepoints before and after exercise. Results: a significant improvement (p = 0.033; 5.2%) of the 8 min TT mean power was observed after CB supplementation compared to placebo. Post-exercise plasma carnosine (p <  0.05) and anserine (p <  0.001) was significantly increased after CB supplementation and not following placebo. No significant effect of CB supplementation was observed either on blood glutathione levels, nor on capillary blood analysis. Conclusions: oral CB supplementation improved the 8 min TT performance albeit it did not affect the acid-base balance or oxidative status parameters. Further research should unravel the potential role and mechanisms of HCD, present in CB, in this ergogenic approach

Geometric Parameterization of J/ΨJ/\Psi Absorption in Heavy Ion Collisions

We calculate the survival probability of $J/\Psi$ particles in various colliding systems using a Glauber model. An analysis of recent data has reported a $J/\Psi$-nucleon breakup cross section of 6.2$\pm$0.7 mb derived from an exponential fit to the ratio of $J/\Psi$ to Drell-Yan yields as a function of a simple, linearly-averaged mean path length through the nuclear medium. Our calculations indicate that, due to the nature of the calculation, this approach yields an apparent breakup cross section which is systematically lower than the actual value.Comment: LaTex, 7 pages, 2 figure

Correlations and charge distributions of medium heavy nuclei

The effects of long- and short-range correlations on the charge distributions of some medium and heavy nuclei are investigated. The long-range correlations are treated within the Random Phase Approximation framework and the short-range correlations with a model inspired to the Correlation Basis Function theory. The two type of correlations produce effects of the same order of magnitude. A comparison with the empirical charge distribution difference between 206Pb and 205Tl shows the need of including both correlations to obtain a good description of the data.Comment: 20 pages, Latex, accepted for publication in Jour. Phys.