Resolving Vega and the inclination controversy with CHARA/MIRC

Optical and infrared interferometers definitively established that the photometric standard Vega (alpha Lyrae) is a rapidly rotating star viewed nearly pole-on. Recent independent spectroscopic analyses could not reconcile the inferred inclination angle with the observed line profiles, preferring a larger inclination. In order to resolve this controversy, we observed Vega using the six-beam Michigan Infrared Combiner on the Center for High Angular Resolution Astronomy Array. With our greater angular resolution and dense (u,v)-coverage, we find Vega is rotating less rapidly and with a smaller gravity darkening coefficient than previous interferometric results. Our models are compatible with low photospheric macroturbulence and also consistent with the possible rotational period of ~0.71 days recently reported based on magnetic field observations. Our updated evolutionary analysis explicitly incorporates rapid rotation, finding Vega to have a mass of 2.15+0.10_-0.15 Msun and an age 700-75+150 Myrs, substantially older than previous estimates with errors dominated by lingering metallicity uncertainties (Z=0.006+0.003-0.002).Comment: Accepted for publication in ApJ Letter

Disappearance of the extended main sequence turn-off in intermediate age clusters as a consequence of magnetic braking

Context. Extended main sequence turn-offs are features commonly found in the colour-magnitude diagrams of young and intermediate age (less than about 2 Gyr) massive star clusters, where the main sequence turn-off is broader than can be explained by photometric uncertainties, crowding, or binarity. Rotation is suspected to be the cause of this feature, by accumulating fast rotating stars, strongly affected by gravity darkening and rotation-induced mixing, near the main sequence turn-off. This scenario successfully reproduces the tight relation between the age and the actual extent in luminosity of the extended main sequence turn-off of observed clusters. Aims. Below a given mass (dependent on the metallicity), stars are efficiently braked early on the main sequence due to the interaction of stellar winds and the surface magnetic field, making their tracks converge towards those of non-rotating tracks in the Hertzsprung-Russell diagram. When these stars are located at the turn-off of a cluster, their slow rotation causes the extended main sequence turn-off feature to disappear. We investigate the maximal mass for which this braking occurs at different metallicities, and determine the age above which no extended main sequence turn-off is expected in clusters. Methods. We used two sets of stellar models (computed with two different stellar evolution codes: STAREVOL and the Geneva stellar evolution code) including the effects of rotation and magnetic braking, at three different metallicities. We implemented them in the SYCLIST toolbox to compute isochrones and then determined the extent of the extended main sequence turn-off at different ages. Results. Our models predict that the extended main sequence turn-off phenomenon disappears at ages older than about 2 Gyr. There is a trend with the metallicity, the age at which the disappearance occurs becoming older at higher metallicity. These results are robust between the two codes used in this work, despite some differences in the input physics and in particular in the detailed description of rotation-induced internal processes and of angular momentum extraction by stellar winds. Conclusions. Comparing our results with clusters in the Large Magellanic Cloud and Galaxy shows a very good fit to the observations. This strengthens the rotation scenario to explain the cause of the extended main sequence turn-off phenomenon

Clarifying the relationship between metformin, acute kidney injury and lactic acidosis

No abstract available

A young cluster with an extended main-sequence turnoff: Confirmation of a prediction of the stellar rotation scenario

We present Hubble Space Telescope photometry of NGC 1850, a ~100 Myr, ~105 M⊙ cluster in the Large Magellanic Cloud. The colour-magnitude diagram clearly shows the presence of an extended main-sequence turnoff (eMSTO). The use of non-rotating stellar isochrones leads to an age spread of ~40 Myr. This is in good agreement with the age range expected when the effects of rotation in the main-sequence turnoff (MSTO) stars are wrongly interpreted in terms of age spread. We also do not find evidence for multiple, isolated episodes of star formation bursts within the cluster, in contradiction to scenarios that invoke actual age spreads to explain the eMSTO phenomenon. NGC 1850 therefore continues the trend of eMSTO clusters, where the inferred age spread is proportional to the age of the cluster. While our results confirm a key prediction of the scenario where stellar rotation causes the eMSTO feature, direct measurements of the rotational rate of MSTO stars is required to definitively confirm or refute whether stellar rotation is the origin of the eMSTO phenomenon or if it is due to an as yet undiscovered effect. © 2016 The Authors

Electrophysiological correlates of high-level perception during spatial navigation

We studied the electrophysiological basis of object recognition by recording scalp\ud electroencephalograms while participants played a virtual-reality taxi driver game.\ud Participants searched for passengers and stores during virtual navigation in simulated\ud towns. We compared oscillatory brain activity in response to store views that were targets or\ud nontargets (during store search) or neutral (during passenger search). Even though store\ud category was solely defined by task context (rather than by sensory cues), frontal ...\ud \u

Does a SLAP lesion affect shoulder muscle recruitment as measured by EMG activity during a rugby tackle?

Background: The study objective was to assess the influence of a SLAP lesion on onset of EMG activity in shoulder muscles during a front on rugby football tackle within professional rugby players. Methods: Mixed cross-sectional study evaluating between and within group differences in EMG onset times. Testing was carried out within the physiotherapy department of a university sports medicine clinic. The test group consisted of 7 players with clinically diagnosed SLAP lesions, later verified on arthroscopy. The reference group consisted of 15 uninjured and full time professional rugby players from within the same playing squad. Controlled tackles were performed against a tackle dummy. Onset of EMG activity was assessed from surface EMG of Pectorialis Major, Biceps Brachii, Latissimus Dorsi, Serratus Anterior and Infraspinatus muscles relative to time of impact. Analysis of differences in activation timing between muscles and limbs (injured versus non-injured side and non injured side versus matched reference group). Results: Serratus Anterior was activated prior to all other muscles in all (P = 0.001-0.03) subjects. In the SLAP injured shoulder Biceps was activated later than in the non-injured side. Onset times of all muscles of the noninjured shoulder in the injured player were consistently earlier compared with the reference group. Whereas, within the injured shoulder, all muscle activation timings were later than in the reference group. Conclusions: This study shows that in shoulders with a SLAP lesion there is a trend towards delay in activation time of Biceps and other muscles with the exception of an associated earlier onset of activation of Serratus anterior, possibly due to a coping strategy to protect glenohumeral stability and thoraco-scapular stability. This trend was not statistically significant in all cases

Feeling low, thinking slow? Associations between situational cues, mood and cognitive function

Within-person changes in mood, which are triggered by situational cues, for example someone’s location or company, are thought to affect contemporaneous cognitive function. To test this hypothesis, data were collected over 6 months with the smartphone application (app) moo-Q that prompted users at random times to rate their mood and complete 3 short cognitive tests. Out of 24,313 people across 154 countries, who downloaded the app, 770 participants submitted 10 or more valid moo-Q responses (mean = 23; SD = 18; range 10–207). Confirming previous research, consistent patterns of association emerged for 6 different situation cues with mood and cognitive function: For example, being alone rather than with others when completing the app resulted in worse mood but better cognitive task performance. Notwithstanding, changes in mood and cognitive function were not coupled. The advantages and challenges of using smartphone technology for studying mood and cognitive function are discussed

Slowing and cooling molecules and neutral atoms by time-varying electric field gradients

A method of slowing, accelerating, cooling, and bunching molecules and neutral atoms using time-varying electric field gradients is demonstrated with cesium atoms in a fountain. The effects are measured and found to be in agreement with calculation. Time-varying electric field gradient slowing and cooling is applicable to atoms that have large dipole polarizabilities, including atoms that are not amenable to laser slowing and cooling, to Rydberg atoms, and to molecules, especially polar molecules with large electric dipole moments. The possible applications of this method include slowing and cooling thermal beams of atoms and molecules, launching cold atoms from a trap into a fountain, and measuring atomic dipole polarizabilities.Comment: 13 pages, 10 figures. Scheduled for publication in Nov. 1 Phys. Rev.