5,926 research outputs found
Detoxification in rehabilitation in England: effective continuity of care or unhappy bedfellows?
There is evidence that residential detoxification alone does not provide satisfactory treatment outcomes and that outcomes are significantly enhanced when clients completing residential detoxification attend rehabilitation services (Gossop, Marsden, Stewart, & Rolfe, 1999; Ghodse, Reynolds, Baldacchino, et al., 2002). One way of increasing the likelihood of this continuity of treatment is by providing detoxification and rehabilitation within the same treatment facility to prevent drop-out, while the client awaits a rehabilitation bed or in the transition process. However, there is little research evidence available on the facilities that offer both medical detoxification and residential rehabilitation. The current study compares self-reported treatment provision in 87 residential rehabilitation services in England, 34 of whom (39.1%) reported that they offered detoxification services within their treatment programmes. Although there were no differences in self-reported treatment philosophies, residential rehabilitation services that offered detoxification were typically of shorter duration overall, had significantly more beds and reported offering more group work than residential rehabilitation services that did not offer detoxification. Outcomes were also different, with twice as many clients discharged on disciplinary grounds from residential rehabilitation services without detoxification facilities. The paper questions the UK classification of residential drug treatment services as either detoxification or rehabilitation and suggests the need for greater research focus on the aims, processes and outcomes of this group of treatment providers
Pyrrole-Imidazole Polyamides Distinguish Between Double-Helical DNA and RNA
Groove specificity: Pyrrole-imidazole polyamides are well-known for their specific interactions with the minor groove of DNA (see scheme). However, polyamides do not show similar binding to duplex RNA, and a structural rationale for the molecular-level discrimination of nucleic acid duplexes by minor-groove-binding ligands is presented
General Relativistic Simulations of Jet Formation in a Rapidly Rotating Black Hole Magnetosphere
To investigate the formation mechanism of relativistic jets in active
galactic nuclei and micro-quasars, we have developed a new general relativistic
magnetohydrodynamic code in Kerr geometry. Here we report on the first
numerical simulation of jet formation in a rapidly-rotating (a=0.95) Kerr black
hole magnetosphere. We study cases in which the Keplerian accretion disk is
both co-rotating and counter-rotating with respect to the black hole rotation.
In the co-rotating disk case, our results are almost the same as those in
Schwarzschild black hole cases: a gas pressure-driven jet is formed by a shock
in the disk, and a weaker magnetically-driven jet is also generated outside the
gas pressure-driven jet. On the other hand, in the counter-rotating disk case,
a new powerful magnetically-driven jet is formed inside the gas pressure-driven
jet. The newly found magnetically-driven jet in the latter case is accelerated
by a strong magnetic field created by frame dragging in the ergosphere. Through
this process, the magnetic field extracts the energy of the black hole
rotation.Comment: Co-rotating and counter-rotating disks; 8 pages; submitted to ApJ
letter
Observation and uses of position-space Bloch oscillations in an ultracold gas
We report the direct observation and characterization of position-space Bloch
oscillations using an ultracold gas in a tilted optical lattice. While Bloch
oscillations in momentum space are a common feature of optical lattice
experiments, the real-space center-of-mass dynamics are typically too small to
resolve. Tuning into the regime of rapid tunneling and weak force, we observe
real-space Bloch oscillation amplitudes of hundreds of lattice sites, in both
ground and excited bands. We demonstrate two unique capabilities enabled by
tracking of Bloch dynamics in position space: measurement of the full
position-momentum phase-space evolution during a Bloch cycle, and direct
imaging of the lattice band structure. These techniques, along with the ability
to exert long-distance coherent control of quantum gases without modulation,
may open up new possibilities for quantum control and metrology.Comment: 5 pages, 6 figure
Elementary solution to the time-independent quantum navigation problem
A quantum navigation problem concerns the identification of a time-optimal Hamiltonian that realizes a required quantum process or task, under the influence of a prevailing ‘background’ Hamiltonian that cannot be manipulated. When the task is to transform one quantum state into another, finding the solution in closed form to the problem is nontrivial even in the case of timeindependent Hamiltonians. An elementary solution, based on trigonometric analysis, is found here when the Hilbert space dimension is two. Difficulties arising from generalizations to higher-dimensional systems are discussed
In the Shadow of the Accretion Disk: Higher Resolution Imaging of the Central Parsec in NGC 4261
The physical conditions in the inner parsec of accretion disks believed to
orbit the central black holes in active galactic nuclei can be probed by
imaging the absorption (by ionized gas in the disk) of background emission from
a radio counterjet. We report high angular resolution VLBI observations of the
nearby (about 40 Mpc) radio galaxy NGC 4261 that confirm free-free absorption
of radio emission from a counterjet by a geometrically thin, nearly edge-on
disk at 1.6, 4.8, and 8.4 GHz. The angular width and depth of the absorption
appears to increase with decreasing frequency, as expected. We derive an
average electron density of ~10E4 per cc at a disk radius of about 0.2 pc,
assuming that the inner disk inclination and opening angles are the same as at
larger radii. Pressure balance between the thermal gas and the magnetic field
in the disk implies an average field strength of 0.1 milligauss at a radius of
0.2 pc. These are the closest-in free-free absorption measurements to date of
the conditions in an extragalactic accretion disk orbiting a black hole with a
well-determined mass. If a standard advection-dominated accretion flow exists
in the disk center, then the transition between thin and thick disk regions
must occur at a radius less than 0.2 pc (4000 Schwarzschild radii).Comment: 20 pages including 12 figures. Accepted for publication in Ap
Down but not out: properties of the molecular gas in the stripped Virgo Cluster early-type galaxy NGC4526
We present ALMA data on the 3mm continuum emission, CO isotopologues (12CO,
13CO, C18O), and high-density molecular tracers (HCN, HCO+, HNC, HNCO, CS, CN,
and CH3OH) in NGC4526. These data enable a detailed study of the physical
properties of the molecular gas in a longtime resident of the Virgo Cluster;
comparisons to more commonly-studied spiral galaxies offer intriguing hints
into the processing of molecular gas in the cluster environment. Many molecular
line ratios in NGC4526, along with our inferred abundances and CO/H2 conversion
factors, are similar to those found in nearby spirals. One striking exception
is the very low observed 12CO/13CO(1-0) line ratio, , which is
unusually low for spirals though not for Virgo Cluster early-type galaxies. We
carry out radiative transfer modeling of the CO isotopologues with some
archival (2-1) data, and we use Bayesian analysis with Markov chain Monte Carlo
techniques to infer the physical properties of the CO-emitting gas. We find
surprisingly low [12CO/13CO] abundance ratios of and
at radii of 0.4 kpc and 1 kpc. The emission from the
high-density tracers HCN, HCO+, HNC, CS and CN is also relatively bright, and
CN is unusually optically thick in the inner parts of NGC4526. These features
hint that processing in the cluster environment may have removed much of the
galaxy's relatively diffuse, optically thinner molecular gas along with its
atomic gas. Angular momentum transfer to the surrounding intracluster medium
may also have caused contraction of the disk, magnifying radial gradients such
as we find in [13CO/C18O]. More detailed chemical evolution modeling would be
interesting in order to explore whether the unusual [12CO/13CO] abundance ratio
is entirely an environmental effect or whether it also reflects the relatively
old stellar population in this early-type galaxy.Comment: Submitted to ApJ. Comments are welcome
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