132,567 research outputs found
Vibrational transfer functions for base excited systems
Computer program GD203 develops transfer functions to compute governing vibration environment for complex structures subjected to a base motion
Nature of fault planes in solid neutron star matter
The properties of tectonic earthquake sources are compared with those deduced
here for fault planes in solid neutron-star matter. The conclusion that
neutron-star matter cannot exhibit brittle fracture at any temperature or
magnetic field is significant for current theories of pulsar glitches, and of
the anomalous X-ray pulsars and soft-gamma repeaters.Comment: 5 AAS LaTeX pages 1 eps figur
Public contracts as accountability mechanisms: assuring quality in public healthcare in England and Wales
Contracting in the public sector is designed to enhance the accountability of service providers to their funders. The idea is that quality is improved by the use of service specifications, monitoring of performance and imposition of contractual sanctions. Socio-legal and economic theories of contract indicate that it will be difficult to make and enforce contracts to achieve this. The results of a study of National Health Services contracting in England and Wales are reported. We conclude that contracts alone are not sufficient to improve accountability – collibration of various regulatory measures (including more hierarchical mechanisms such as performance targets) is required
Overview of the Status and Strangeness Capabilities of STAR
STAR is a large acceptance spectrometer capable of precision measurements of
a wide variety of strange particles. We discuss the STAR detector, its
configuration during the first two years of RHIC operation, and its initial
performance for Au+Au collisions. The expected performance for strangeness
physics and initial data on strange particle reconstruction in Au+Au collisions
are presented.Comment: Proceedings of the Fifth International Conference on Strangeness in
Quark Matter, Berkeley, California, July 20-25, 200
Opening angles, Lorentz factors and confinement of X-ray binary jets
We present a collation of the available data on the opening angles of jets in
X-ray binaries, which in most cases are small (less than 10 degrees). Under the
assumption of no confinement, we calculate the Lorentz factors required to
produce such small opening angles via the transverse relativistic Doppler
effect. The derived Lorentz factors, which are in most cases lower limits, are
found to be large, with a mean greater than 10, comparable to those estimated
for AGN and much higher than the commonly-assumed values for X-ray binaries of
2 to 5. Jet power constraints do not in most cases rule out such high Lorentz
factors. The upper limits on the opening angles show no evidence for smaller
Lorentz factors in the steady jets of Cygnus X-1 and GRS 1915+105. In those
sources in which deceleration has been observed (notably XTE J1550-564 and
Cygnus X-3), some confinement of the jets must be occurring, and we briefly
discuss possible confinement mechanisms. It is however possible that all the
jets could be confined, in which case the requirement for high bulk Lorentz
factors can be relaxed.Comment: 11 pages, 4 figures (2 colour), accepted for publication in MNRA
The Disturbed 17 keV Cluster Associated with the Radio Galaxy 3C 438
We present results from a {\em Chandra} observation of the cluster gas
associated with the FR II radio galaxy 3C 438. This radio galaxy is embedded
within a massive cluster with gas temperature 17 keV and bolometric
luminosity of 6 ergs s. It is unclear if this high
temperature represents the gravitational mass of the cluster, or if this is an
already high ( 11 keV) temperature cluster that has been heated
transiently. We detect a surface brightness discontinuity in the gas that
extends 600 kpc through the cluster. The radio galaxy 3C 438 is too small
(110 kpc across) and too weak to have created this large disturbance in
the gas. The discontinuity must be the result of either an extremely powerful
nuclear outburst or the major merger of two massive clusters. If the observed
features are the result of a nuclear outburst, it must be from an earlier epoch
of unusually energetic nuclear activity. However, the energy required
( ergs) to move the gas on the observed spatial scales strongly
supports the merger hypothesis. In either scenario, this is one of the most
extreme events in the local Universe.Comment: 13 pages, 4 figures, 1 table - accepted for publication in the
Astrophysical Journal Letter
Cryogenic propellant venting under low pressure conditions Final report
Wall temperatures and heat transfer coefficients for solid-vapor mixtures of para hydrogen and nitrogen venting under low pressur
The Nature of the Low-Metallicity ISM in the Dwarf Galaxy NGC 1569
We are modeling the spectra of dwarf galaxies from infrared to submillimeter
wavelengths to understand the nature of the various dust components in
low-metallicity environments, which may be comparable to the ISM of galaxies in
their early evolutionary state. The overall nature of the dust in these
environments appears to differ from those of higher metallicity starbursting
systems. Here, we present a study of one of our sample of dwarf galaxies, NGC
1569, which is a nearby, well-studied starbursting dwarf. Using ISOCAM, IRAS,
ISOPHOT and SCUBA data with the Desert et al. (1990) model, we find consistency
with little contribution from PAHs and Very Small Grains and a relative
abundance of bigger colder grains, which dominate the FIR and submillimeter
wavelengths. We are compelled to use 4 dust components, adding a very cold dust
component, to reproduce the submillimetre excess of our observations.Comment: 4 pages, 4 postscript figures. Proceedings of "Infrared and
Submillimeter Astronomy. An International Colloquium to Honor the Memory of
Guy Serra" (2002
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