New near-infrared period-luminosity-metallicity relations for RR Lyrae stars and the outlook for GAIA

We present results of the analysis of 70 RR Lyrae stars located in the bar of the Large Magellanic Cloud (LMC). Combining the spectroscopically determined metallicity of these stars from the literature with precise periods from the OGLE III catalog and multi-epoch Ks photometry from the VISTA survey of the Magellanic Clouds system, we derive a new near-infrared period-luminosity-metallicity (PLKsZ) relation for RR Lyrae variables. In order to fit the relation we use a fitting method developed specifically for this study. The zero-point of the relation is estimated two different ways: by assuming the value of the distance to the LMC and by using Hubble Space Telescope parallaxes of five RR Lyrae stars in the Milky Way (MW). The difference in distance moduli derived by applying these two approaches is ~0.2 mag. To investigate this point further we derive the PLKsZ relation based on 23 MW RR Lyrae stars that had been analyzed in Baade-Wesselink studies. We compared the derived PLKsZ relations for RR Lyrae stars in the MW and LMC. Slopes and zero-points are different, but still consistent within the errors. The shallow slope of the metallicity term is confirmed by both LMC and MW variables. The astrometric space mission Gaia is expected to provide a huge contribution to the determination of the RR Lyrae PLKsZ relation; however, calculating an absolute magnitude from the trigonometric parallax of each star and fitting a PLKsZ relation directly to period and absolute magnitude leads to biased results. We present a tool to achieve an unbiased solution by modeling the data and inferring the slope and zero-point of the relation via statistical methods.Peer reviewedFinal Accepted Versio

Cutaneous vasoconstriction as a measure of incipient autonomic dysreflexia during penile vibratory stimulation in spinal cord injury

Measurement of haemodynamic responses, cutaneous blood flow and sweat release during penile vibratory stimulation (PVS) in spinal cord-injured men. To assess the validity of using markers of sympathetic activity (cutaneous blood flow and sweat release) as a measure of incipient autonomic dysreflexia during PVS in spinal cord-injured men. Prince of Wales Medical Research Institute, Australia. Ten spinal cord-injured men with injuries ranging from C3 to T6. Continuous arterial pressure, intermittent auscultation, heart rate (HR), respiration, cutaneous blood flow and sweat release from both finger and toe were recorded during PVS. Vibration of the penis caused immediate cutaneous vasoconstriction, but negligible sweat release, in the hands and feet of the quadriplegics and the feet of the paraplegics. Systolic blood pressure (BP) increased by up to 90 mm Hg, and a compensatory vagal bradycardia was observed in five of the six quadriplegics and two of the four paraplegic subjects. Given that there was-in general-an inverse relationship between BP and skin blood flow, we conclude that continuous measurements of skin blood flow above and below the lesion can provide important information on the state of the sympathetic nervous system and early identification of reflexly evoked increases in sympathetic vasoconstrictor drive, below a spinal lesion. Coupled with a decrease in HR, this cutaneous vasoconstriction infers an increased BP