1,850 research outputs found
Culturally Competent California Mental Health Services: Model and Example
Mental health services in the United States were designed for European American consumers, but with burgeoning multicultural populations these services have proven inadequate and underutilized. This paper examines research on cultural competencies of agencies and clinicians relevant to a mental health practice model, the Multicultural Assessment-Intervention Process model (MAIP). This model was modified for systematic application in a California agency, the Tri-City Mental Health Center, to provide a flexible blueprint for major alterations in agency practice and programs that affect the entire system of care. MAIP begins with intake process including client-clinician/ethnicity-Ianguage|match, client acculturation/racial identity status, and clinician cultural competence, and proceeds to clinician in-service-training, cultural components embedded in services, and outcome measures
Detecting massive gravitons using pulsar timing arrays
At the limit of weak static fields, general relativity becomes Newtonian gravity with a potential field that falls off as inverse distance rather than a theory of Yukawa-type fields with a finite range. General relativity also predicts that the speed of disturbances of its waves is c, the vacuum light speed, and is non-dispersive. For these reasons, the graviton, the boson for general relativity, can be considered to be massless. Massive gravitons, however, are features of some alternatives to general relativity. This has motivated experiments and observations that, so far, have been consistent with the zero-mass graviton of general relativity, but further tests will be valuable. A basis for new tests may be the high sensitivity gravitational wave (GW) experiments that are now being performed and the higher sensitivity experiments that are being planned. In these experiments, it should be feasible to detect low levels of dispersion due to non-zero graviton mass. One of the most promising techniques for such a detection may be the pulsar timing program that is sensitive to nano-Hertz GWs. Here, we present some details of such a detection scheme. The pulsar timing response to a GW background with the massive graviton is calculated, and the algorithm to detect the massive graviton is presented. We conclude that, with 90% probability, massless gravitons can be distinguished from gravitons heavier than 3 × 10-22 eV (Compton wavelength λg = 4.1 × 1012 km), if bi-weekly observation of 60 pulsars is performed for 5 years with a pulsar rms timing accuracy of 100 ns. If 60 pulsars are observed for 10 years with the same accuracy, the detectible graviton mass is reduced to 5 × 10-23 eV (λg = 2.5 × 1013 km); for 5 year observations of 100 or 300 pulsars, the sensitivity is respectively 2.5 × 10-22 (λg = 5.0 × 1012 km) and 10-22 eV (λg = 1.2 × 1013 km). Finally, a 10 year observation of 300 pulsars with 100 ns timing accuracy would probe graviton masses down to 3 × 10-23 eV (λ g = 4.1 × 1013 km). © 2010. The American Astronomical Society. All rights reserved. Printed in the U.S.A
Nonexistence of conformally flat slices of the Kerr spacetime
Initial data for black hole collisions are commonly generated using the
Bowen-York approach based on conformally flat 3-geometries. The standard
(constant Boyer-Lindquist time) spatial slices of the Kerr spacetime are not
conformally flat, so that use of the Bowen-York approach is limited in dealing
with rotating holes. We investigate here whether there exist foliations of the
Kerr spacetime that are conformally flat. We limit our considerations to
foliations that are axisymmetric and that smoothly reduce in the Schwarzschild
limit to slices of constant Schwarzschild time. With these restrictions, we
show that no conformally flat slices can exist.Comment: 5 LaTeX pages; no figures; to be submitted to Phys. Rev.
Detecting massive gravitons using pulsar timing arrays
Massive gravitons are features of some alternatives to general relativity.
This has motivated experiments and observations that, so far, have been
consistent with the zero mass graviton of general relativity, but further tests
will be valuable. A basis for new tests may be the high sensitivity
gravitational wave experiments that are now being performed, and the higher
sensitivity experiments that are being planned. In these experiments it should
be feasible to detect low levels of dispersion due to nonzero graviton mass.
One of the most promising techniques for such a detection may be the pulsar
timing program that is sensitive to nano-Hertz gravitational waves.
Here we present some details of such a detection scheme. The pulsar timing
response to a gravitational wave background with the massive graviton is
calculated, and the algorithm to detect the massive graviton is presented. We
conclude that, with 90% probability, massles gravitons can be distinguished
from gravitons heavier than eV (Compton wave length
km), if biweekly observation of 60 pulsars
are performed for 5 years with pulsar RMS timing accuracy of 100 ns. If 60
pulsars are observed for 10 years with the same accuracy, the detectable
graviton mass is reduced to eV ( km); for 5-year observations of 100 or 300 pulsars, the sensitivity is
respectively ( km) and
eV ( km). Finally, a 10-year
observation of 300 pulsars with 100 ns timing accuracy would probe graviton
masses down to eV ( km).Comment: 13 pages, 5 figures, Accepted by Ap
Observability of pulsar beam bending by the Sgr~A* black hole
According to some models, there may be a significant population of radio
pulsars in the Galactic center. In principle, a beam from one of these pulsars
could pass close to the supermassive black hole (SMBH) at the center, be
deflected, and be detected by Earth telescopes. Such a configuration would be
an unprecedented probe of the properties of spacetime in the moderate- to
strong-field regime of the SMBH. We present here background on the problem, and
approximations for the probability of detection of such beams. We conclude that
detection is marginally probable with current telescopes, but that telescopes
that will be operating in the near future, with an appropriate multiyear
observational program, will have a good chance of detecting a beam deflected by
the SMBH.Comment: 18 pages, 16 figure
Black Hole Data via a Kerr-Schild Approach
We present a new approach for setting initial Cauchy data for multiple black
hole spacetimes. The method is based upon adopting an initially Kerr-Schild
form of the metric. In the case of non-spinning holes, the constraint equations
take a simple hierarchical form which is amenable to direct numerical
integration. The feasibility of this approach is demonstrated by solving
analytically the problem of initial data in a perturbed Schwarzschild geometry.Comment: 13 pages, RevTeX forma
- …