Beat Cepheids as Probes of Stellar and Galactic Metallicity

The mere location of a Beat Cepheid model in a Period Ratio vs. Period diagram (Petersen diagram) puts very tight constraints on its metallicity Z. The Beat Cepheid Peterson diagrams are revisited with linear nonadiabatic turbulent convective models, and their accuracy as a probe for stellar metallicity is evaluated. They are shown to be largely independent of the helium content Y, and they are also only weakly dependent on the mass-luminosity relation that is used in their construction. However, they are found to show sensitivity to the relative abundances of the elements that are lumped into the metallicity parameter Z. Rotation is estimated to have but a small effect on the 'pulsation metallicities'. A composite Petersen diagram is presented that allows one to read off upper and lower limits on the metallicity Z from the measured period P0 and period ratio P1/P0.Comment: 9 pages, 12 color figures (black and white version available from 1st author's website). With minor revisions. to appear in Ap

Taking a Dip in the Supreme Court Clerk Pool: Gender-Based Discrepancies in Clerk Selection

Former U.S. Supreme Court clerks are heavily recruited by select law firms, and many eventually find their way to policy “elite” positions in the government or in the legal academy. A number of former clerks have returned to the Court as litigators, and a subset has returned to the Court as Justices. We are interested in clerk selection for two reasons. First, clerks influence key aspects of the judicial process while serving in their clerkship capacity, and second, many seem to be in a good position to influence legal policy well after their clerkships have ended. With this in mind, it is natural to ask about the selection of such individuals to these posts. There are larger questions of diversity, however, that have permeated discussions of the Court’s clerkship selection practices. In this Article, we explore one critical dimension—the relative imbalance between men and women serving as High Court clerks. We analyze the U.S. Supreme Court directly, but also supply comparison points in assessing clerkship diversity in Canada and Brazil

A Bayesian approach to the modelling of alpha Cen A

Determining the physical characteristics of a star is an inverse problem consisting in estimating the parameters of models for the stellar structure and evolution, knowing certain observable quantities. We use a Bayesian approach to solve this problem for alpha Cen A, which allows us to incorporate prior information on the parameters to be estimated, in order to better constrain the problem. Our strategy is based on the use of a Markov Chain Monte Carlo (MCMC) algorithm to estimate the posterior probability densities of the stellar parameters: mass, age, initial chemical composition,... We use the stellar evolutionary code ASTEC to model the star. To constrain this model both seismic and non-seismic observations were considered. Several different strategies were tested to fit these values, either using two or five free parameters in ASTEC. We are thus able to show evidence that MCMC methods become efficient with respect to more classical grid-based strategies when the number of parameters increases. The results of our MCMC algorithm allow us to derive estimates for the stellar parameters and robust uncertainties thanks to the statistical analysis of the posterior probability densities. We are also able to compute odds for the presence of a convective core in alpha Cen A. When using core-sensitive seismic observational constraints, these can raise above ~40%. The comparison of results to previous studies also indicates that these seismic constraints are of critical importance for our knowledge of the structure of this star.Comment: 21 pages, 6 figures, to be published in MNRA

Analysis of Total and Segmental Body Composition Relative to Fitness Performance Measures in Law Enforcement Recruits

International Journal of Exercise Science 15(4): 245-260, 2022. Law enforcement agencies often test the fitness performance and body composition of incoming recruits. This study investigated the relationships between whole and segmental body composition, and fitness tests in law enforcement recruits. A retrospective analysis of 72 male and 11 female recruits was performed. Bioelectrical impedance analysis (BIA) variables were: lean mass (LM), upper-extremity lean mass (UELM), trunk LM, lower-extremity lean mass (LELM), fat mass (FM), upper-extremity fat mass (UEFM), trunk FM, and lower-extremity fat mass (LEFM). Fitness tests included: vertical jump (VJ), peak anaerobic power (PAPw), 75-yard pursuit run (75PR), push-ups, sit-ups, 2-kg medicine ball throw (MBT), and the multi-stage fitness test (MSFT). Partial correlations and ANCOVAs between quartiles assessed relationships between body composition and performance. Significant moderate-to-large relationships were found; LM, UELM, trunk LM, LELM all related to PAPw (r = 0.500-0.558) and MBT (r = 0.494-0.526). FM, UEFM, trunk FM, LEFM all related to VJ (r = -0.481 to -0.493), 75PR (r = 0.533-0.557), push-ups (r = -0.484 to -0.503), sit-ups (r = -0.435 to -0.449), and MSFT (r = -0.371 to -0.423). The highest LM quartile (4) had superior PAPw and MBT than LM quartiles 1-3. Higher FM quartiles performed poorer in VJ, push-ups, and sit-ups. The 75PR quartiles 2, 3, and 4 were slower than quartile 1, and MSFT quartile 4 completed less shuttles. Total and segmental measures of LM and FM shared the same relationships; lower FM and higher LM related to better performance. Monitoring body composition could help guide training to optimize performance

NuSTAR Observations of the Magnetar 1E 2259+586

We report on new broad band spectral and temporal observations of the magnetar 1E 2259+586, which is located in the supernova remnant CTB 109. Our data were obtained simultaneously with the Nuclear Spectroscopic Telescope Array (NuSTAR) and Swift, and cover the energy range from 0.5-79 keV. We present pulse profiles in various energy bands and compare them to previous RXTE results. The NuSTAR data show pulsations above 20 keV for the first time and we report evidence that one of the pulses in the double-peaked pulse profile shifts position with energy. The pulsed fraction of the magnetar is shown to increase strongly with energy. Our spectral analysis reveals that the soft X-ray spectrum is well characterized by an absorbed double-blackbody or blackbody plus power-law model in agreement with previous reports. Our new hard X-ray data, however, suggests that an additional component, such as a power-law, is needed to describe the NuSTAR and Swift spectrum. We also fit the data with the recently developed coronal outflow model by Beloborodov for hard X-ray emission from magnetars. The outflow from a ring on the magnetar surface is statistically preferred over outflow from a polar cap.Comment: 37 pages, 9 figures, corresponding author, [email protected]

NuSTAR observations of X-ray bursts from the magnetar 1E 1048.1-5937

We report the detection of eight bright X-ray bursts from the 6.5-s magnetar 1E 1048.1-5937, during a 2013 July observation campaign with the Nuclear Spectroscopic Telescope Array (NuSTAR). We study the morphological and spectral properties of these bursts and their evolution with time. The bursts resulted in count rate increases by orders of magnitude, sometimes limited by the detector dead time, and showed blackbody spectra with kT=6-8 keV in the T90 duration of 1-4 s, similar to earlier bursts detected from the source. We find that the spectra during the tail of the bursts can be modeled with an absorbed blackbody with temperature decreasing with flux. The bursts flux decays followed a power-law of index 0.8-0.9. In the burst tail spectra, we detect a ~13 keV emission feature, similar to those reported in previous bursts from this source as well as from other magnetars observed with the Rossi X-ray Timing Explorer (RXTE). We explore possible origins of the spectral feature such as proton cyclotron emission, which implies a magnetic field strength of B~2X10^15 G in the emission region. However, the consistency of the energy of the feature in different objects requires further explanation.Comment: 10 pages, 6 figures, accepted for publication in Ap

The eSMA: description and first results

The eSMA ("extended SMA") combines the SMA, JCMT and CSO into a single facility, providing enhanced sensitivity and spatial resolution owing to the increased collecting area at the longest baselines. Until ALMA early science observing (2011), the eSMA will be the facility capable of the highest angular resolution observations at 345 GHz. The gain in sensitivity and resolution will bring new insights in a variety of fields, such as protoplanetary/transition disks, high-mass star formation, solar system bodies, nearby and high-z galaxies. Therefore the eSMA is an important facility to prepare the grounds for ALMA and train scientists in the techniques. Over the last two years, and especially since November 2006, there has been substantial progress toward making the eSMA into a working interferometer. In particular, (i) new 345-GHz receivers, that match the capabilities of the SMA system, were installed at the JCMT and CSO; (ii) numerous tests have been performed for receiver, correlator and baseline calibrations in order to determine and take into account the effects arising from the differences between the three types of antennas; (iii) first fringes at 345 GHz were obtained on August 30 2007, and the array has entered the science-verification stage. We report on the characteristics of the eSMA and its measured performance at 230 GHz and that expected at 345 GHz. We also present the results of the commissioning and some initial science-verification observations, including the first absorption measurement of the C/CO ratio in a galaxy at z=0.89, located along the line of sight to the lensed quasar PKS1830-211, and on the imaging of the vibrationally excited HCN line towards IRC+10216.Comment: 12 pages, 7 figures, paper number 7012-12, to appear in Proceedings of SPIE vol. 7012: "Ground-based and Airborne Telescopes II", SPIE conference on Astronomical Instrumentation, Marseille, 23-28 June 200