FUSE Observations of a Full Orbit of Hercules X-1: Signatures of Disk, Star, and Wind

We observed an entire 1.7 day orbit of the X-ray binary Hercules X-1 with the Far Ultraviolet Spectroscopic Explorer (FUSE). Changes in the O VI 1032,1037 line profiles through eclipse ingress and egress indicate a Keplerian accretion disk spinning prograde with the orbit. These observations may show the first double-peaked accretion disk line profile to be seen in the Hercules X-1 system. Doppler tomograms of the emission lines show a bright spot offset from the Roche lobe of the companion star HZ Her, but no obvious signs of the accretion disk. Simulations show that the bright spot is too far offset from the Roche lobe to result from uneven X-ray heating of its surface. The absence of disk signatures in the tomogram can be reproduced in simulations which include absorption from a stellar wind. We attempt to diagnose the state of the emitting gas from the C III 977, C III 1175, and N III 991 emission lines. The latter may be enhanced through Bowen fluorescence.Comment: Accepted for publication in The Astrophysical Journa

The thermodynamics of prediction

A system responding to a stochastic driving signal can be interpreted as computing, by means of its dynamics, an implicit model of the environmental variables. The system's state retains information about past environmental fluctuations, and a fraction of this information is predictive of future ones. The remaining nonpredictive information reflects model complexity that does not improve predictive power, and thus represents the ineffectiveness of the model. We expose the fundamental equivalence between this model inefficiency and thermodynamic inefficiency, measured by dissipation. Our results hold arbitrarily far from thermodynamic equilibrium and are applicable to a wide range of systems, including biomolecular machines. They highlight a profound connection between the effective use of information and efficient thermodynamic operation: any system constructed to keep memory about its environment and to operate with maximal energetic efficiency has to be predictive.Comment: 5 pages, 1 figur

An Organizational Quality Improvement Project Exploring Diversity, Equity, and Inclusion Opportunities

Aims: The purpose of this participatory action quality improvement project was to identify challenges and member-driven solutions to enhance diversity, equity, and inclusion (DEI) in a regional nursing research society (RNRS). Methods: This project adhered to a quality improvement (QI) framework and drew on strategies used in participatory action research to collect data on member-identified organizational practices that support and/or limit DEI within the RNRS, and member-generated solutions to enhance DEI within the society. The QI team consisted of RNRS members serving on a DEI Task Force and members with qualitative methods expertise. The team conducted focus groups during the society’s annual meeting and collected quantitative and qualitative data using a cross-sectional survey sent to all society members following the annual meeting. Results: Preliminary findings of this project in progress (PIP) indicate membership willingness to identify DEI issues and potential organizational solutions. Preliminary focus group data demonstrated members’ desires to encourage and support underrepresented members of the society. Potential solutions suggested by membership included creating mechanisms for financial support of underrepresented current/prospective members, increasing transparency in executive board decision-making, and creating more robust mechanisms for new member orientation and existing member professional development through a formal mentorship program. Conclusions: This PIP provides an exemplar of nursing research societies’ potential capacity to engage members in efforts to enhance organizational DEI. Efforts to create regional nursing research societies that are more inclusive and more accurately reflect the broader population is an important first step in supporting research on social and structural determinants of health

A burst from the direction of UZ Fornacis with XMM-Newton

The XMM-Newton pointing towards the magnetic cataclysmic variable UZ For finds the source to be a factor > 10^3 fainter than previous EXOSAT and ROSAT observations. The source was not detected for the majority of a 22 ksec exposure with the EPIC cameras, suggesting that the accretion rate either decreased, or stopped altogether. However a 1.1 ksec burst was detected from UZ For during the observation. Spectral fits favour optically thin, kT = 4.4 keV thermal emission. Detection of the burst by the on-board Optical Monitor indicates that this was most probably an accretion event. The 0.1-10 keV luminosity of 2.1 x 10^30 erg/s is typical for accretion shock emission from high state polars and would result from the potential energy release of ~ 10^16 g of gas. There is no significant soft excess due to reprocessing in the white dwarf atmosphere.Comment: 7 pages, 2 postscript figures, ApJL, in pres

Spot patterns and differential rotation in the eclipsing pre-CV binary,V471 Tau

We present surface spot maps of the K2V primary star in the pre-cataclysmic variable binary system, V471 Tau. The spot maps show the presence of large high latitude spots located at the sub-white dwarf longitude region. By tracking the relative movement of spot groups over the course of four nights (eight rotation cycles), we measure the surface differential rotation rate of the system.Our results reveal that the star is rotating rigidly with a surface shear rate, dOmega = 1.6 +/- 6 mrad/d. The single active star AB Dor has a similar spectral type, rotation period, and activity level as the K star in V471 Tau but displays much stronger surface shear (46 < dOmega < 58 mrad/d). Our results suggest that tidal locking may inhibit differential rotation; this reduced shear, however, does not affect the overall magnetic activity levels in active K dwarfs.Comment: 12 pages, 9 figures, accepted by MNRA

Quasi-Homogeneous Thermodynamics and Black Holes

We propose a generalized thermodynamics in which quasi-homogeneity of the thermodynamic potentials plays a fundamental role. This thermodynamic formalism arises from a generalization of the approach presented in paper [1], and it is based on the requirement that quasi-homogeneity is a non-trivial symmetry for the Pfaffian form $\delta Q_{rev}$. It is shown that quasi-homogeneous thermodynamics fits the thermodynamic features of at least some self-gravitating systems. We analyze how quasi-homogeneous thermodynamics is suggested by black hole thermodynamics. Then, some existing results involving self-gravitating systems are also shortly discussed in the light of this thermodynamic framework. The consequences of the lack of extensivity are also recalled. We show that generalized Gibbs-Duhem equations arise as a consequence of quasi-homogeneity of the thermodynamic potentials. An heuristic link between this generalized thermodynamic formalism and the thermodynamic limit is also discussed.Comment: 39 pages, uses RevteX. Published version (minor changes w.r.t. the original one

Ornamental plants, 1982: a summary of research

Growth of Taxus cuspidata 'Thayeri' produced in containers / Elton M. Smith and Sharon A. Treaster -- A comparison of plant growth in poly bags produced on capillary irrigation / Elton M. Smith and Sharon A. Treaster -- Sodium chloride phytotoxicity to sugar maple / Elton M. Smith and Sharon A. Treaster -- Effects of fertilizer in the propagation medium and extended photo period on rooting of Acer rubrum 'Red Sunset' / Steven M. Still and Bryce H. Lane -- Comparisons of growth for chrysanthemums and poinsettias produced in prototypes of a new container and four potting media / Richard P. Ventanovetz and John C. Peterson -- Effects of pH upon nutrient availability in a commercial soilless root medium utilized for floral crop production / John C. Peterson -- An evaluation of pre-emergence herbicides on tulip and narcissus / Elton M. Smith and Sharon A. Treaster -- An evaluation of hot sauce for prevention of mice and deer damage in a commercial nursery / Elton M. Smith and Thomas M. Stockdale -- Test results of fungicides for control of diseases of ornamentals / C. C. Powell -- Virus-indexed rose plants: first-year performance results / C. C. Powel