329 research outputs found
Multiple impact therapy : evaluation and design for future study
The theoretical underpinnings of Washington County Children\u27s Services Division (CSD) Immediate Conflict-Resolution Family Treatment Program include the systems theory of family therapy with a focus on communication and roles. One of the many approaches to helping families in crisis, it incorporates theories regarding assessment of and intervention in families in crisis. Finally, while it draws upon several different approaches to family therapy, the Washington County program is most closely related to Multiple Impact Therapy (MIT). Thus, a review of relevant literature must address portions of the above enumerated theories that illuminate the thinking behind the Immediate Conflict- Resolution Family Treatment Program. While each of the four components of the literature review (systems theory, family crisis theory, assessment of families in crisis, and Multiple Impact Therapy) represents a topic area of breadth and complexity, the aspects of each topic area which seem most relevant to Washington County\u27s MIT project have been reviewed
Spin Flipping and Polarization Lifetimes of a 270 MeV Deuteron Beam
We recently studied the spin flipping of a 270 MeV vertically polarized deuteron beam stored in the IUCF Cooler Ring. We swept an rf solenoidâs frequency through an rfâinduced spin resonance and observed the effect on the beamâs vector and tensor polarizations. After optimizing the resonance crossing rate and setting the solenoidâs voltage to its maximum value, we obtained a spinâflip efficiency of about 94 ± 1% for the vector polarization; we also observed a partial spinâflip of the tensor polarization. We then used the rfâinduced resonance to measure the vector and tensor polarizationsâ lifetimes at different distances from the resonance; the polarization lifetime ratio Ïvector/Ïtensor was about 1.9 ± 0.4. © 2003 American Institute of PhysicsPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87679/2/766_1.pd
Mass transport by buoyant bubbles in galaxy clusters
We investigate the effect of three important processes by which AGN-blown
bubbles transport material: drift, wake transport and entrainment. The first of
these, drift, occurs because a buoyant bubble pushes aside the adjacent
material, giving rise to a net upward displacement of the fluid behind the
bubble. For a spherical bubble, the mass of upwardly displaced material is
roughly equal to half the mass displaced by the bubble, and should be ~
10^{7-9} solar masses depending on the local ICM and bubble parameters. We show
that in classical cool core clusters, the upward displacement by drift may be a
key process in explaining the presence of filaments behind bubbles. A bubble
also carries a parcel of material in a region at its rear, known as the wake.
The mass of the wake is comparable to the drift mass and increases the average
density of the bubble, trapping it closer to the cluster centre and reducing
the amount of heating it can do during its ascent. Moreover, material dropping
out of the wake will also contribute to the trailing filaments. Mass transport
by the bubble wake can effectively prevent the build-up of cool material in the
central galaxy, even if AGN heating does not balance ICM cooling. Finally, we
consider entrainment, the process by which ambient material is incorporated
into the bubble. AbridgedComment: Accepted for publication in MNRAS. 17 pages, 4 figures, 2 tables.
Formatted for letter paper and adjusted author affiliations
Transition probabilities for general birth-death processes with applications in ecology, genetics, and evolution
A birth-death process is a continuous-time Markov chain that counts the
number of particles in a system over time. In the general process with
current particles, a new particle is born with instantaneous rate
and a particle dies with instantaneous rate . Currently no robust and
efficient method exists to evaluate the finite-time transition probabilities in
a general birth-death process with arbitrary birth and death rates. In this
paper, we first revisit the theory of continued fractions to obtain expressions
for the Laplace transforms of these transition probabilities and make explicit
an important derivation connecting transition probabilities and continued
fractions. We then develop an efficient algorithm for computing these
probabilities that analyzes the error associated with approximations in the
method. We demonstrate that this error-controlled method agrees with known
solutions and outperforms previous approaches to computing these probabilities.
Finally, we apply our novel method to several important problems in ecology,
evolution, and genetics
What is a Cool-Core Cluster? A Detailed Analysis of the Cores of the X-ray Flux-Limited HIFLUGCS Cluster Sample
We use the largest complete sample of 64 galaxy clusters (HIghest X-ray FLUx
Galaxy Cluster Sample) with available high-quality X-ray data from Chandra, and
apply 16 cool-core diagnostics to them, some of them new. We also correlate
optical properties of brightest cluster galaxies (BCGs) with X-ray properties.
To segregate cool core and non-cool-core clusters, we find that central cooling
time, t_cool, is the best parameter for low redshift clusters with high quality
data, and that cuspiness is the best parameter for high redshift clusters. 72%
of clusters in our sample have a cool core (t_cool < 7.7 h_{71}^{-1/2} Gyr) and
44% have strong cool cores (t_cool <1.0 h_{71}^{-1/2} Gyr). For the first time
we show quantitatively that the discrepancy in classical and spectroscopic mass
deposition rates can not be explained with a recent formation of the cool
cores, demonstrating the need for a heating mechanism to explain the cooling
flow problem. [Abridged]Comment: 45 pages, 19 figures, 7 tables. Accepted for publication in A&A.
Contact Person: Rupal Mittal ([email protected]
A Chandra X-ray Analysis of Abell 1664: Cooling, Feedback and Star Formation in the Central Cluster Galaxy
The brightest cluster galaxy (BCG) in the Abell 1664 cluster is unusually
blue and is forming stars at a rate of ~ 23 M_{\sun} yr^{-1}. The BCG is
located within 5 kpc of the X-ray peak, where the cooling time of 3.5x10^8 yr
and entropy of 10.4 keV cm^2 are consistent with other star-forming BCGs in
cooling flow clusters. The center of A1664 has an elongated, "bar-like" X-ray
structure whose mass is comparable to the mass of molecular hydrogen, ~ 10^{10}
M_{\sun} in the BCG. We show that this gas is unlikely to have been stripped
from interloping galaxies. The cooling rate in this region is roughly
consistent with the star formation rate, suggesting that the hot gas is
condensing onto the BCG. We use the scaling relations of Birzan et al. 2008 to
show that the AGN is underpowered compared to the central X-ray cooling
luminosity by roughly a factor of three. We suggest that A1664 is experiencing
rapid cooling and star formation during a low-state of an AGN feedback cycle
that regulates the rates of cooling and star formation. Modeling the emission
as a single temperature plasma, we find that the metallicity peaks 100 kpc from
the X-ray center, resulting in a central metallicity dip. However, a
multi-temperature cooling flow model improves the fit to the X-ray emission and
is able to recover the expected, centrally-peaked metallicity profile.Comment: 15 pages, 13 figure
Remote Sensing of Environment: Current status of Landsat program, science, and applications
Formal planning and development of what became the first Landsat satellite commenced over 50 years ago in 1967. Now, having collected earth observation data for well over four decades since the 1972 launch of Landsat- 1, the Landsat program is increasingly complex and vibrant. Critical programmatic elements are ensuring the continuity of high quality measurements for scientific and operational investigations, including ground systems, acquisition planning, data archiving and management, and provision of analysis ready data products. Free and open access to archival and new imagery has resulted in a myriad of innovative applications and novel scientific insights. The planning of future compatible satellites in the Landsat series, which maintain continuity while incorporating technological advancements, has resulted in an increased operational use of Landsat data. Governments and international agencies, among others, can now build an expectation of Landsat data into a given operational data stream. International programs and conventions (e.g., deforestation monitoring, climate change mitigation) are empowered by access to systematically collected and calibrated data with expected future continuity further contributing to the existing multi-decadal record. The increased breadth and depth of Landsat science and applications have accelerated following the launch of Landsat-8, with significant improvements in data quality.
Herein, we describe the programmatic developments and institutional context for the Landsat program and the unique ability of Landsat to meet the needs of national and international programs. We then present the key trends in Landsat science that underpin many of the recent scientific and application developments and followup with more detailed thematically organized summaries. The historical context offered by archival imagery combined with new imagery allows for the development of time series algorithms that can produce information on trends and dynamics. Landsat-8 has figured prominently in these recent developments, as has the improved understanding and calibration of historical data. Following the communication of the state of Landsat science, an outlook for future launches and envisioned programmatic developments are presented. Increased linkages between satellite programs are also made possible through an expectation of future mission continuity, such as developing a virtual constellation with Sentinel-2. Successful science and applications developments create a positive feedback loopâjustifying and encouraging current and future programmatic support for Landsat
An Expert Consensus Statement on the Management of Large Chondral and Osteochondral Defects in the Patellofemoral Joint
© The Author(s) 2020. Background: Cartilage lesions of the patellofemoral joint constitute a frequent abnormality. Patellofemoral conditions are challenging to treat because of complex biomechanics and morphology. Purpose: To develop a consensus statement on the functional anatomy, indications, donor graft considerations, surgical treatment, and rehabilitation for the management of large chondral and osteochondral defects in the patellofemoral joint using a modified Delphi technique. Study Design: Consensus statement. Methods: A working group of 4 persons generated a list of statements related to the functional anatomy, indications, donor graft considerations, surgical treatment, and rehabilitation for the management of large chondral and osteochondral defects in the patellofemoral joint to form the basis of an initial survey for rating by a group of experts. The Metrics of Osteochondral Allografts (MOCA) expert group (composed of 28 high-volume cartilage experts) was surveyed on 3 occasions to establish a consensus on the statements. In addition to assessing agreement for each included statement, experts were invited to propose additional statements for inclusion or to suggest modifications of existing statements with each round. Predefined criteria were used to refine statement lists after each survey round. Statements reaching a consensus in round 3 were included within the final consensus document. Results: A total of 28 experts (100% response rate) completed 3 rounds of surveys. After 3 rounds, 36 statements achieved a consensus, with over 75% agreement and less than 20% disagreement. A consensus was reached in 100.00% of the statements relating to functional anatomy of the patellofemoral joint, 88.24% relating to surgical indications, 100.00% relating to surgical technical aspects, and 100.00% relating to rehabilitation, with an overall consensus of 95.5%. Conclusion: This study established a strong expert consensus document relating to the functional anatomy, surgical indications, donor graft considerations for osteochondral allografts, surgical technical aspects, and rehabilitation concepts for the management of large chondral and osteochondral defects in the patellofemoral joint. Further research is required to clinically validate the established consensus statements and better understand the precise indications for surgery as well as which techniques and graft processing/preparation methods should be used based on patient- and lesion-specific factors
Effects of antiplatelet therapy on stroke risk by brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases: subgroup analyses of the RESTART randomised, open-label trial
Background
Findings from the RESTART trial suggest that starting antiplatelet therapy might reduce the risk of recurrent symptomatic intracerebral haemorrhage compared with avoiding antiplatelet therapy. Brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases (such as cerebral microbleeds) are associated with greater risks of recurrent intracerebral haemorrhage. We did subgroup analyses of the RESTART trial to explore whether these brain imaging features modify the effects of antiplatelet therapy
Magnetic turbulence in cool cores of galaxy clusters
We argue that the recently reported Kolmogorov-like magnetic turbulence
spectrum in the cool core of the Hydra A galaxy cluster can be understood by
kinetic energy injection by active galaxies that drives a turbulent non-helical
magnetic dynamo into its saturated state. Although dramatic differences exist
between small-scale dynamo scenarios, their saturated state is expected to be
similar, as we show for three scenarios: the flux rope dynamo, the fluctuation
dynamo, and the explosive dynamo. Based on those scenarios, we develop an
analytical model of the hydrodynamic and magnetic turbulence in cool cores. The
model implies magnetic field strengths that fit well with Faraday rotation
measurements and minimum energy estimates for the sample of cool core clusters
having such data available. Predictions for magnetic fields in clusters for
which the appropriate observational information is still missing, and for yet
unobserved quantities like the hydrodynamical turbulence velocity and
characteristic length-scale are provided. The underlying dynamo models suggest
magnetic intermittency and possibly a large-scale hydrodynamic viscosity. We
conclude that the success of the model to explain the field strength in cool
core clusters indicates that in general cluster magnetic fields directly
reflect hydrodynamical turbulence, also in clusters without cool cores.Comment: 15 pages, 4 figures, A&A in pres
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