5,243 research outputs found
Display for binary characters Patent
Cathode ray tube system for displaying ones and zeros in binary wave trai
Low-Mass X-Ray Binaries, Millisecond Radio Pulsars, and the Cosmic Star Formation Rate
We report on the implications of the peak in the cosmic star-formation rate
(SFR) at redshift z ~ 1.5 for the resulting population of low-mass X-ray
binaries(LMXB) and for that of their descendants, the millisecond radio pulsars
(MRP). Since the evolutionary timescales of LMXBs, their progenitors, and their
descendants are thought be significant fractions of the time-interval between
the SFR peak and the present epoch, there is a lag in the turn-on of the LMXB
population, with the peak activity occurring at z ~ 0.5 - 1.0. The peak in the
MRP population is delayed further, occurring at z < 0.5. We show that the
discrepancy between the birthrate of LMXBs and MRPs, found under the assumption
of a stead-state SFR, can be resolved for the population as a whole when the
effects of a time-variable SFR are included. A discrepancy may persist for
LMXBs with short orbital periods, although a detailed population synthesis will
be required to confirm this. Further, since the integrated X-ray luminosity
distribution of normal galaxies is dominated by X-ray binaries, it should show
strong luminosity evolution with redshift. In addition to an enhancement near
the peak (z ~ 1.5) of the SFR due to the prompt turn-on of the relatively
short-lived massive X-ray binaries and young supernova remnants, we predict a
second enhancement by a factor ~10 at a redshift between ~ 0.5 and ~ 1 due to
the delayed turn-on of the LMXB population. Deep X-ray observations of galaxies
out to z ~ 1 by AXAF will be able to observe this enhancement, and, by
determining its shape as a function of redshift, will provide an important new
method for constraining evolutionary models of X-ray binaries.Comment: 13 pages, including 1 figure. Accepted for publication in ApJ Letter
Satellite and ground radiotracking of elk
Radiotracking and monitoring of free-living animals in natural environments is providing an effective new technique for acquiring information on biological processes, including animal orientation and navigation. To test the practicability of extending the technique by using satellite systems for tracking animals, a female elk was instrumented with an electronic collar. It contained both the Interrogation Recording Location System (IRLS) transponder and a Craighead-Varney ground-tracking transmitter. The elk was successfully tracked and monitored by satellite during month of April 1970. This was the first time an animal had been tracked by satellite on the surface of the earth
Management of incidentally detected heart murmurs in dogs and cats
A dog or a cat has an incidentally detected heart murmur if the murmur is an unexpected discovery during a veterinary consultation that was not initially focused on the cardiovascular system. This document presents approaches for managing dogs and cats that have incidentally-detected heart murmurs, with an emphasis on murmur characteristics, signalment profiling, and multifactorial decision-making to choose an optimal course for a given patient
Satellite data relay and platform locating in oceanography. Report of the In Situ Ocean Science Working Group
The present and future use of satellites to locate offshore platforms and relay data from in situ sensors to shore was examined. A system of the ARGOS type will satisfy the increasing demand for oceanographic information through data relay and platform location. The improved ship navigation provided by the Global Positioning System (GPS) will allow direct observation of currents from underway ships. Ocean systems are described and demand estimates on satellite systems are determined. The capabilities of the ARGOS system is assessed, including anticipated demand in the next decade
The Next Generation Virgo Cluster Survey (NGVS). XVIII. Measurement and Calibration of Surface Brightness Fluctuation Distances for Bright Galaxies in Virgo (and Beyond)
We describe a program to measure surface brightness fluctuation (SBF)
distances to galaxies observed in the Next Generation Virgo Cluster Survey
(NGVS), a photometric imaging survey covering of the Virgo cluster
in the bandpasses with the Canada-France Hawaii Telescope. We
describe the selection of the sample galaxies, the procedures for measuring the
apparent -band SBF magnitude , and the calibration of the absolute
as a function of observed stellar population properties. The
multi-band NGVS data set provides multiple options for calibrating the SBF
distances, and we explore various calibrations involving individual color
indices as well as combinations of two different colors. Within the color range
of the present sample, the two-color calibrations do not significantly improve
the scatter with respect to wide-baseline, single-color calibrations involving
. We adopt the calibration as reference for the present
galaxy sample, with an observed scatter of 0.11 mag. For a few cases that lack
good photometry, we use an alternative relation based on a combination
of and colors, with only a slightly larger observed scatter of
0.12 mag. The agreement of our measurements with the best existing distance
estimates provides confidence that our measurements are accurate. We present a
preliminary catalog of distances for 89 galaxies brighter than
mag within the survey footprint, including members of the background M and W
Clouds at roughly twice the distance of the main body of the Virgo cluster. The
extension of the present work to fainter and bluer galaxies is in progress.Comment: ApJ accepte
A Photometric Technique to Search for Be Stars in Open Clusters
We describe a technique to identify Be stars in open clusters using Stromgren
b, y, and narrow-band Halpha photometry. We first identify the B-type stars of
the cluster using a theoretical isochrone fit to the (b-y, y) color-magnitude
diagram. The strongest Be stars are easily identified in a (b-y, y-Halpha)
color-color diagram, but those with weaker Halpha emission (classified as
possible Be star detections) may be confused with evolved or foreground stars.
Here we present such photometry plus Halpha spectroscopy of members of the
cluster NGC 3766 to demonstrate the accuracy of our technique. Statistical
results on the relative numbers of Be and B-type stars in additional clusters
will be presented in a future paper.Comment: 15 pages, 6 figures, 1 table. Accepted by Ap
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