6,587 research outputs found
On the size and shape of excluded volume polymers confined between parallel plates
A number of recent experiments have provided detailed observations of the
configurations of long DNA strands under nano-to-micrometer sized confinement.
We therefore revisit the problem of an excluded volume polymer chain confined
between two parallel plates with varying plate separation. We show that the
non-monotonic behavior of the overall size of the chain as a function of
plate-separation, seen in computer simulations and reproduced by earlier
theories, can already be predicted on the basis of scaling arguments. However,
the behavior of the size in a plane parallel to the plates, a quantity observed
in recent experiments, is predicted to be monotonic, in contrast to the
experimental findings. We analyze this problem in depth with a mean-field
approach that maps the confined polymer onto an anisotropic Gaussian chain,
which allows the size of the polymer to be determined separately in the
confined and unconfined directions. The theory allows the analytical
construction of a smooth cross-over between the small plate-separation de
Gennes regime and the large plate-separation Flory regime. The results show
good agreement with Langevin dynamics simulations, and confirm the scaling
predictions.Comment: 15 pages, 3 figure
Non-circular Gas Kinematics and Star Formation in the Ringed Galaxy NGC 4736
We analyze the gas kinematics and star formation properties of the nearby
RSab galaxy NGC 4736 using interferometric and single-dish CO(1-0) data and
previously published Halpha and HI data. The CO morphology is dominated by a
central molecular bar and tightly wound spiral arms associated with a bright
ring of star formation. Strong HI emission is also found in the ring, but HI is
absent from the central regions. Comparison of the HI and Halpha distributions
suggests that HI in the ring is primarily dissociated H. Modeling of the CO
kinematics reveals gas motion in elliptical orbits around the central bar, and
we argue that the ring represents both the OLR of the bar and the ILR of a
larger oval distortion. The HI kinematics show evidence for axisymmetric inflow
towards the ring and are inconsistent with streaming in aligned elliptical
orbits, but the highly supersonic (~40 km/s) inflow velocities required,
corresponding to mass inflow rates of ~2 Msol/yr, suggest that more
sophisticated models (e.g., gas orbiting in precessed elliptical orbits) should
be considered. The radial CO and Halpha profiles are poorly correlated in the
vicinity of the nuclear bar, but show a better correlation (in rough agreement
with the Schmidt law) at the ring. Even along the ring, however, the azimuthal
correspondence between CO and Halpha is poor, suggesting that massive stars
form more efficiently at some (perhaps resonant) locations than at others.
These results indicate that the star formation rate per unit gas mass exhibits
strong spatial variations and is not solely a function of the available gas
supply. The localization of star formation to the ring is broadly consistent
with gravitational instability theory, although the instability parameter on average in the ring, only falling below 1 in localized regions.Comment: Revised version accepted by ApJ, with new section on p-v diagrams. 24
pages with 24 figures (emulateapj5). Full resolution and color versions are
available at http://astro.berkeley.edu/~twong/preprint
Determinants of Quality of Life and Treatment Satisfaction During Long-Term Involuntary In-patient Treatment of Dual-Diagnosis Patients
INTRODUCTION: Treatment resistance and disengagement from mental health services are major obstacles in the treatment of dual diagnosis patients with Severe Mental Illness. The patients in this study were admitted to a long-term involuntary treatment facility. AIM OF THE STUDY: To study which patient experiences and perceptions are related to the outcome measures Subjective Quality of Life (SQOL) and Treatment Satisfaction (TS) during the long-term involuntary treatment. METHODS: Patients were invited for an interview by an independent researcher, which included self-report questionnaires. The structured interviews included self-assessing Helping Alliance, Insight, Attitude toward involuntary admission, Perceived coercion and Perceived benefit were studied as determinants of SQOL and TS. The relationship between the determinants and the outcomes were analyzed by linear regression analysis. RESULTS: Patient reported outcomes from dual diagnosis patients in a long-term treatment facility, showed that most of the patients, in spite of the involuntary character of the treatment, were satisfied with the treatment. With respect to the determinants of SQOL and TS the perceptions that “My opinion is taken into account” and “Perceived benefits of the treatment” are strong predictors of both the outcomes. CONCLUSIONS: The current study shows that the most important aspects for treatment satisfaction and quality of life of dual-diagnosis patients admitted involuntary to long-term treatment, are being listened to (being taken seriously) and experiencing improvements during treatment. These qualities reflect the goals of Shared Decision Making and Perceived Procedural Justice in treatment. The study also corroborates earlier findings that even when treated involuntarily, patients might not hold particular negative views regarding their treatment
Dutch Mental Health Patients’ and Significant Others’ Perspectives on Compulsory Treatment at Home:One Size Does Not Fit All
Ultraviolet Signposts of Resonant Dynamics in the Starburst-Ringed Sab Galaxy, M94 (NGC 4736)
M94 (NGC 4736) is investigated using images from the Ultraviolet Imaging
Telescope (FUV-band), Hubble Space Telescope (NUV-band), Kitt Peak 0.9-m
telescope (H-alpha, R, and I bands), and Palomar 5-m telescope (B-band), along
with spectra from the International Ultraviolet Explorer and Lick 1-m
telescopes. The wide-field UIT image shows FUV emission from (a) an elongated
nucleus, (b) a diffuse inner disk, where H-alpha is observed in absorption, (c)
a bright inner ring of H II regions at the perimeter of the inner disk (R = 48
arcsec. = 1.1 kpc), and (d) two 500-pc size knots of hot stars exterior to the
ring on diametrically opposite sides of the nucleus (R= 130 arcsec. = 2.9 kpc).
The HST/FOC image resolves the NUV emission from the nuclear region into a
bright core and a faint 20 arcsec. long ``mini-bar'' at a position angle of 30
deg. Optical and IUE spectroscopy of the nucleus and diffuse inner disk
indicates an approximately 10^7 or 10^8 yr-old stellar population from
low-level starbirth activity blended with some LINER activity. Analysis of the
H-alpha, FUV, NUV, B, R, and I-band emission along with other observed tracers
of stars and gas in M94 indicates that most of the star formation is being
orchestrated via ring-bar dynamics involving the nuclear mini-bar, inner ring,
oval disk, and outer ring. The inner starburst ring and bi-symmetric knots at
intermediate radius, in particular, argue for bar-mediated resonances as the
primary drivers of evolution in M94 at the present epoch. Similar processes may
be governing the evolution of the ``core-dominated'' galaxies that have been
observed at high redshift. The gravitationally-lensed ``Pretzel Galaxy''
(0024+1654) at a redshift of approximately 1.5 provides an important precedent
in this regard.Comment: revised figure 1 (corrected coordinate labels on declination axis);
19 pages of text + 19 figures (jpg files); accepted for publication in A
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