17,026 research outputs found
Nuclear Bar, Star Formation and Gas Fueling in the Active Galaxy NGC 4303
A combination of Hubble Space Telescope (HST) WFPC2 and NICMOS images are
used to investigate the gas/dust and stellar structure inside the central 300
pc of the nearby active galaxy NGC 4303.
The NICMOS H-band (F160W) image reveals a bright core and a nuclear elongated
bar-like structure of 250 pc in diameter. The bar is centered on the bright
core, and its major axis is oriented in proyection along the spin axis of the
nuclear gaseous rotating disk recently detected (Colina & Arribas 1999).
The V-H (F606W - F160W) image reveals a complex gas/dust distribution with a
two-arm spiral structure of about 225 pc in radius. The southwestern arm is
traced by young star-forming knots while the northeastern arm is detected by
the presence of dust lanes. These spirals do not have a smooth structure but
rather they are made of smaller flocculent spirals or filament-like structures.
The magnitudes and colors of the star-forming knots are typical of clusters of
young stars with masses of 0.5 to 1 x yr^{-1} for about 80 Myr.Comment: ApJ, in press (February 1, 2000
Towards durable multistakeholder-generated solutions: The pilot application of a problem-oriented policy learning protocol to legality verification and community rights in Peru
This paper reports and reflects on the pilot application of an 11-step policy learning protocol that was developed by Cashore and Lupberger (2015) based on several years of Cashore’s multi-author collaborations. The protocol was applied for the first time in Peru in 2015 and 2016 by the IUFRO Working Party on Forest Policy Learning Architectures (hereinafter referred to as the project team). The protocol integrates insights from policy learning scholarship (Hall 1993, Sabatier 1999) with Bernstein and Cashore’s (2000, 2012) four pathways of influence framework. The pilot implementation in Peru focused on how global timber legality verification interventions might be harnessed to promote local land rights. Legality verification focuses attention on the checking and auditing of forest management units in order to verify that timber is harvested and traded in compliance with the law. We specifically asked: How can community legal ownership of, and access to, forestland and forest resources be enhanced? The protocol was designed as a dynamic tool, the implementation of which fosters iterative rather than linear processes. It directly integrated two objectives: 1) identifying the causal processes through which global governance initiatives might be harnessed to produce durable results ‘on the ground’; 2) generating insights and strategies in collaboration with relevant stakeholders. This paper reviews and critically evaluates our work in designing and piloting the protocol. We assess what seemed to work well and suggest modifications, including an original diagnostic framework for nurturing durable change. We also assess the implications of the pilot application of the protocol for policy implementation that works to enhance the influence of existing international policy instruments, rather than contributing to fragmentation and incoherence by creating new ones
The foundations of the working alliance in assertive community treatment teams
Abstract Background In this study, we aimed to identify and define the fundamental components of the working alliance in multidisciplinary (Flexible) Assertive Community Treatment teams with shared caseloads, in order to support their daily practice and further research. Methods After reviewing the literature, concept mapping with professionals and clients was used to define the working alliance in (F) ACT teams. The resulting concept maps formed the basis for the working alliance assessment instrument, which was pilot tested with professionals and clients through cognitive interviews with a think-aloud procedure. Results The study led to the development of a twenty five-item assessment instrument to evaluate working alliances in multidisciplinary teams (WAM) that was comprised of three subscales: bond, task/goal and team. Two different versions were developed for clients and professionals. Conclusions The WAM instrument was developed to determine the quality of the working alliance in (F) ACT teams. Future research will focus on testing its psychometric properties and predictive value
Towards a fully self-consistent spectral function of the nucleon in nuclear matter
We present a calculation of nuclear matter which goes beyond the usual
quasi-particle approximation in that it includes part of the off-shell
dependence of the self-energy in the self-consistent solution of the
single-particle spectrum. The spectral function is separated in contributions
for energies above and below the chemical potential. For holes we approximate
the spectral function for energies below the chemical potential by a
-function at the quasi-particle peak and retain the standard form for
energies above the chemical potential. For particles a similar procedure is
followed. The approximated spectral function is consistently used at all levels
of the calculation. Results for a model calculation are presented, the main
conclusion is that although several observables are affected by the inclusion
of the continuum contributions the physical consistency of the model does not
improve with the improved self-consistency of the solution method. This in
contrast to expectations based on the crucial role of self-consistency in the
proofs of conservation laws.Comment: 26 pages Revtex with 4 figures, submitted to Phys. Rev.
A graphene transmon operating at 1 T
A superconducting transmon qubit resilient to strong magnetic fields is an
important component for proposed topological and hybrid quantum computing (QC)
schemes. Transmon qubits consist of a Josephson junction (JJ) shunted by a
large capacitance, coupled to a high quality factor superconducting resonator.
In conventional transmon devices, the JJ is made from an Al/AlO/Al tunnel
junction which ceases operation above the critical magnetic field of Al, 10 mT.
Alternative junction technologies are therefore required to push the operation
of these qubits into strong magnetic fields. Graphene JJs are one such
candidate due to their high quality, ballistic transport and electrically
tunable critical current densities. Importantly the monolayer structure of
graphene protects the JJ from orbital interference effects that would otherwise
inhibit operation at high magnetic field. Here we report the integration of
ballistic graphene JJs into microwave frequency superconducting circuits to
create the first graphene transmons. The electric tunability allows the
characteristic band dispersion of graphene to be resolved via dispersive
microwave spectroscopy. We demonstrate that the device is insensitive to the
applied field and perform energy level spectroscopy of the transmon at 1 T,
more than an order of magnitude higher than previous studies.Comment: attached supplementary materia
Ground-based variability surveys towards Centaurus A: worthwhile or not?
Context: Difference imaging has proven to be a powerful technique for
detecting and monitoring the variability of unresolved stellar sources in M 31.
Using this technique in surveys of galaxies outside the Local Group could have
many interesting applications. Aims: The goal of this paper is to test
difference imaging photometry on Centaurus A, the nearest giant elliptical
galaxy, at a distance of 4 Mpc. Methods: We obtained deep photometric data with
the Wide Field Imager at the ESO/MPG 2.2m at La Silla spread over almost two
months. Applying the difference imaging photometry package DIFIMPHOT, we
produced high-quality difference images and detected variable sources. The
sensitivity of the current observational setup was determined through
artificial residual tests. Results: In the resulting high-quality difference
images, we detect 271 variable stars. We find a difference flux detection limit
corresponding to m_R~24.5. Based on a simple model of the halo of Centaurus A,
we estimate that a ground-based microlensing survey would detect in the order
of 4 microlensing events per year due to lenses in the halo. Conclusions:
Difference imaging photometry works very well at the distance of Centaurus A
and promises to be a useful tool for detecting and studying variable stars in
galaxies outside the local group. For microlensing surveys, a higher
sensitivity is needed than achieved here, which would be possible with a large
ground-based telescope or space observatory with wide-field imaging
capabilities.Comment: 8 pages, 7 figures, accepted for publication in Astronomy and
Astrophysic
The effect of a goal-setting strategy with integrated feedback on goal attainment in inflammatory arthritis patients:a mixed method study
Patients with Inflammatory Arthritis (IA) often experience difficulties in daily life as a result of their disease. Unfortunately, outpatient consultations in daily practice tend to focus on medical topics, thereby ignoring the impact of the disease on patients’ daily lives. Patient-Reported Outcomes (PROs) can be used to understand this impact, but they are not enough for offering person-centered care. Because the patient’s true values and goals can only be ascertained during a proper conversation, which should include both medical as well as patient goals. Therefore, the aim of the study is to evaluate the effect of a goal management strategy with integrated feedback on goal attainment and Health-Related Quality of Life(HRQoL) in IA patients. IA patients with an active disease were given the opportunity to set and follow-up goals. In addition to goal setting, patients were asked to complete online questionnaires on various PROs, including HRQoL. Ninety-two IA patients participated in the study. The mean age was 51 years and most of them had rheumatoid arthritis. A total of 302 patient goals were set, of which 32% were achieved. In the entire population, HRQoL did not change over time, but patients who did not meet their goals tended to report a lower HRQoL. Incorporating a feedback mechanism in a goal-setting strategy has a positive effect on goal attainment. Yet no effect was seen on HRQoL, but this may due to the fact that general HRQoL measurement are not sensitive or specific enough to detect changes that are accompanied with goal setting and attainment.</p
Relativistic Brueckner-Hartree-Fock calculations with explicit intermediate negative energy states
In a relativistic Brueckner-Hartree-Fock calculation we include explicit
negative-energy states in the two-body propagator. This is achieved by using
the Gross spectator-equation, modified by medium effects. Qualitatively our
results compare well with other RBHF calculations. In some details significant
differences occur, e.g, our equation of state is stiffer and the momentum
dependence of the self-energy components is stronger than found in a reference
calculation without intermediate negative energy states.Comment: 13 pages Revtex, 5 figures included seperatel
Shot Noise of Single-Electron Tunneling in 1D Arrays
We have used numerical modeling and a semi-analytical calculation method to
find the low frequency value S_{I}(0) of the spectral density of fluctuations
of current through 1D arrays of small tunnel junctions, using the ``orthodox
theory'' of single-electron tunneling. In all three array types studied, at low
temperature (kT << eV), increasing current induces a crossover from the
Schottky value S_{I}(0)=2e to the ``reduced Schottky value''
S_{I}(0)=2e/N (where N is the array length) at some crossover current I_{c}.
In uniform arrays over a ground plane, I_{c} is proportional to exp(-\lambda
N), where 1/\lambda is the single-electron soliton length. In arrays without a
ground plane, I_{c} decreases slowly with both N and \lambda. Finally, we have
calculated the statistics of I_{c} for ensembles of arrays with random
background charges. The standard deviation of I_{c} from the ensemble average
is quite large, typically between 0.5 and 0.7 of , while the
dependence of on N or \lambda is so weak that it is hidden within the
random fluctuations of the crossover current.Comment: RevTex. 21 pages of text, 10 postscript figure
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