The Binary Second Sequence in Cluster Colour--Magnitude Diagrams

We show how the second sequence seen lying above the main sequence in cluster colour magnitude diagrams results from binaries with a large range of mass ratios and not just from those with equal masses. We conclude that the presence of a densely populated second sequence, with only sparse filling in between it and the single star main sequence, does not necessarily imply that binary mass ratios are close to unity.Comment: Accepted to MNRAS. 5 Pages including 3 figure

Effects of Low pH on Lactate Dehydrogenase Kinetics of Diving and Nondiving Reptiles

The properties of lactate dehydrogenase were examined in two snake species, Nerodia rhombifera and Elaphe obsoleta, and a turtle species, Pseudemys scripta. Our purpose was to compare the LDH activity of reptiles with limited anaerobic capabilities with that of the well established diver Pseudemys. The Michaelis-Menten kinetics of LDH and its susceptibility to inhibition by elevated pyruvate concentrations were investigated in the brain and heart of the three species. All tissue incubations and enzyme activity determinations were done at a pH of 7.0 in order to stimulate a diving blood pH in the three species. In both tissues the LDH activity of the snakes was higher than that of Pseudemys at pyruvate concentrations ranging between .03 mM and .50 mM. The Km values of the snakes were lower than those of Pseudemys, suggesting a greater enzyme-substrate affinity in the snake tissues. The Vmax values were higher in the snake tissues indicating a faster conversion of substrate to product. Heart LDH activity was reduced to an equal extent by high pyruvate concentrations in each of the three species. Elaphe brain LDH was most susceptible to pyruvate inhibition, but Nerodia and Pseudemys brain LDH were inhibited to an equal extent. The results indicate that the kinetic behavior of brain and heart LDH of the three species is similar at a pH of 7.4 and a pH of 7.0. The results also suggest that the LDH of Pseudemys is no better adapted to withstand anaerobic conditions than that of Nerodia or Elaphe at a pH of 7.0

Application of biological filters in water treatment systems

Silver chloride placed on or close to barrier kills bacteria as they arrive. Dead bacteria accumulate linearly, whereas previously, live bacteria accumulated exponentially. During continuous 30-day tests, no bacteriological contamination was found downstream of filters with silver chloride added

Chandra astrometry sets a tight upper limit to the proper motion of SGR 1900+14

The soft gamma-ray repeater (SGR) SGR 1900+14 lies a few arcminutes outside the edge of the shell supernova remnant (SNR) G42.8+0.6. A physical association between the two systems has been proposed - for this and other SGR-SNR pairs - based on the expectation of high space velocities for SGRs in the framework of the magnetar model. The large angular separation between the SGR and the SNR center, coupled with the young age of the system, suggest a test of the association with a proper motion measurement. We used a set of three Chandra/ACIS observations of the field spanning 5 years to perform accurate relative astrometry in order to measure the possible angular displacement of the SGR as a function of time. Our investigation sets a 3-sigma upper limit of 70 mas/yr to the overall proper motion of the SGR. Such a value argues against an association of SGR 1900+14 with G42.8+0.6 and adds further support to the mounting evidence for an origin of the SGR within a nearby, compact cluster of massive stars.Comment: Accepted for publication in The Astrophysical Journal. 4 pages in emulate-apj styl

The Interplanetary Network Supplement to the BeppoSAX Gamma-Ray Burst Catalogs

Between 1996 July and 2002 April, one or more spacecraft of the interplanetary network detected 787 cosmic gamma-ray bursts that were also detected by the Gamma-Ray Burst Monitor and/or Wide-Field X-Ray Camera experiments aboard the BeppoSAX spacecraft. During this period, the network consisted of up to six spacecraft, and using triangulation, the localizations of 475 bursts were obtained. We present the localization data for these events.Comment: 89 pages, 3 figures. Submitted to the Astrophysical Journal Supplement Serie

Potable water bactericide agent development

The results are summarized of the work performed for the development and evaluation of a bactericide agent/system concept capable of being used in the space shuttle potable water system. The concept selected for evaluation doses fuel cell water with silver ions before the water is stored and used, by passing this water through columns packed with silver chloride and silver bromide particles, respectively. Four simulated space shuttle potable water system tests, each of seven days duration, were performed to demonstrate that this concept is capable of delivering sterile water even though 3 + or - 1 x 10 to the 9th power Type IIIa or Pseudomonas aeruginosa bacteria, two types which have been found in the Apollo potable water system, are purposely injected into the system each day. This result, coupled with the fact that silver ions do not have to be periodically added to the stored water, indicates that this concept is superior to the chlorine and iodine techniques used on Apollo

Feasibility study of an Integrated Program for Aerospace-vehicle Design (IPAD) system. Volume 1: Summary

An overview is provided of the Ipad System, including its goals and objectives, organization, capabilities and future usefulness. The systems implementation is also presented with operational cost summaries

Public Health Workforce Shortages Imperil Nation's Health

Examines from a community-based perspective the scope of the shortages in the public health workforce; contributing factors such as inadequate funding, salaries, and benefits; and strategies for training, recruiting, and retaining public health workers

Evolution of binary stars and the effect of tides on binary populations

We present a rapid binary evolution algorithm that enables modelling of even the most complex binary systems. In addition to all aspects of single star evolution, features such as mass transfer, mass accretion, common-envelope evolution, collisions, supernova kicks and angular momentum loss mechanisms are included. In particular, circularization and synchronization of the orbit by tidal interactions are calculated for convective, radiative and degenerate damping mechanisms. We use this algorithm to study the formation and evolution of various binary systems. We also investigate the effect that tidal friction has on the outcome of binary evolution. Using the rapid binary code, we generate a series of large binary populations and evaluate the formation rate of interesting individual species and events. By comparing the results for populations with and without tidal friction we quantify the hitherto ignored systematic effect of tides and show that modelling of tidal evolution in binary systems is necessary in order to draw accurate conclusions from population synthesis work. Tidal synchronism is important but because orbits generally circularize before Roche-lobe overflow the outcome of the interactions of systems with the same semi-latus rectum is almost independent of eccentricity. It is not necessary to include a distribution of eccentricities in population synthesis of interacting binaries, however, the initial separations should be distributed according to the observed distribution of semi-latera recta rather than periods or semi-major axes.Comment: 36 pages, 12 figures, to be published in the Monthly Notices of the Royal Astronomical Societ

Dynamical Interactions Make Hot Jupiters in Open Star Clusters

Explaining the origin and evolution of exoplanetary "hot Jupiters" remains a significant challenge. One possible mechanism for their production is planet-planet interactions, which produces hot Jupiters from planets born far from their host stars but near their dynamical stability limits. In the much more likely case of planets born far from their dynamical stability limits, can hot Jupiters can be formed in star clusters? Our N-body simulations of planetary systems inside star clusters answer this question in the affirmative, and show that hot Jupiter formation is not a rare event. We detail three case studies of the dynamics-induced births of hot Jupiters on highly eccentric orbits that can only occur inside star clusters. The hot Jupiters' orbits bear remarkable similarities to those of some of the most extreme exoplanets known: HAT-P-32 b, HAT-P-2 b, HD 80606 b and GJ 876 d. If stellar perturbations formed these hot Jupiters then our simulations predict that these very hot, inner planets are often accompanied by much more distant gas giants in highly eccentric orbits.Comment: 18 pages, 4 figure