1,203 research outputs found
Complex diffuse radio emission in the merging PLANCK ESZ cluster Abell 3411
We present VLA radio and Chandra X-ray observations of the merging galaxy
cluster Abell 3411. For the cluster, we find an overall temperature of 6.4 keV
and an X-ray luminosity of 2.8 x 10^{44} erg s^{-1} between 0.5 and 2.0 keV.
The Chandra observation reveals the cluster to be undergoing a merger event.
The VLA observations show the presence of large-scale diffuse emission in the
central region of the cluster, which we classify as a 0.9 Mpc size radio halo.
In addition, a complex region of diffuse, polarized emission is found in the
southeastern outskirts of the cluster, along the projected merger axis of the
system. We classify this region of diffuse emission as a radio relic. The total
extent of this radio relic is 1.9 Mpc. For the combined emission in the cluster
region, we find a radio spectral index of -1.0 \pm 0.1 between 74 MHz and 1.4
GHz. The morphology of the radio relic is peculiar, as the relic is broken up
into five fragments. This suggests that the shock responsible for the relic has
been broken up due to interaction with a large-scale galaxy filament connected
to the cluster or other substructures in the ICM. Alternatively, the complex
morphology reflects the presence of electrons in fossil radio bubbles that are
re-accelerated by a shock.Comment: Accepted for publication in ApJ, 8 pages, 5 figure
Integrated silicon qubit platform with single-spin addressability, exchange control and robust single-shot singlet-triplet readout
Silicon quantum dot spin qubits provide a promising platform for large-scale
quantum computation because of their compatibility with conventional CMOS
manufacturing and the long coherence times accessible using Si enriched
material. A scalable error-corrected quantum processor, however, will require
control of many qubits in parallel, while performing error detection across the
constituent qubits. Spin resonance techniques are a convenient path to parallel
two-axis control, while Pauli spin blockade can be used to realize local parity
measurements for error detection. Despite this, silicon qubit implementations
have so far focused on either single-spin resonance control, or control and
measurement via voltage-pulse detuning in the two-spin singlet-triplet basis,
but not both simultaneously. Here, we demonstrate an integrated device platform
incorporating a silicon metal-oxide-semiconductor double quantum dot that is
capable of single-spin addressing and control via electron spin resonance,
combined with high-fidelity spin readout in the singlet-triplet basis.Comment: 10 pages, 4 figure
Advancing a global pharmacy support workforce through a global strategic platform
The pharmacy support workforce (PSW) is the mid-level cadre of the global pharmacy profession, referring to pharmacy technicians, assistants and other cadres that assist in the delivery of pharmaceutical services in a variety of practice contexts. The PSW undertake technical tasks delegated under the supervision of a pharmacist or performed collaboratively. The PSW are not intended to replace pharmacists, but rather work side-by-side with the pharmacist to achieve a shared goal. However, extensive variation in the PSW exists globally, ranging from an educated, regulated, and highly effective workforce in some countries to unrecognized or non-existent in others. Vast differences in education requirements, specific roles, regulatory oversight, and need for pharmacist supervision, inhibit the development and advancement of a global PSW. As clinical care providers, pharmacists worldwide need for a competent support workforce. Without the confidence to delegate technical responsibilities to a well-trained and capable PSW, pharmacists will be unable to fully deliver advanced clinical roles. A clear vision for the role of the PSW in the expanding scope of pharmacy practice is needed. One organization working to unite global efforts in this area is the International Pharmaceutical Federation (FIP). The FIP Workforce Development Hub Pharmacy Technicians & Support Workforce Strategic Platform was established to address the pharmacy workforce shortage in low and middle-income countries. Further developments were made in 2019, with the creation of a representative global PSW advisory panel, to provide guidance towards the development of the global PSW. Provision of frameworks and strategic input to support quality in education, development of legislative frameworks, guidelines for registration and licensure, and advice on appropriate role advancement are critical to move the PSW forward. In order to produce substantial advancement of roles and recognition of the PSW and advancement of pharmacists as patient care providers, global collaborative work is needed
Optimal fishery with coastal catch
In many spatial resource models, it is assumed that an agent is able to harvest the resource over the complete spatial domain. However, agents frequently only have access to a resource at particular locations at which a moving biomass, such as fish or game, may be caught or hunted. Here, we analyze an infinite timeâhorizon optimal control problem with boundary harvesting and (systems of) parabolic partial differential equations as state dynamics. We formally derive the associated canonical system, consisting of a forwardâbackward diffusion system with boundary controls, and numerically compute the canonical steady states and the optimal timeâdependent paths, and their dependence on parameters. We start with some oneâspecies fishing models, and then extend the analysis to a predatorâprey model of the LotkaâVolterra type. The models are rather generic, and our methods are quite general, and thus should be applicable to large classes of structurally similar bioeconomic problems with boundary controls.
Recommedations for Resource Managers
Just like ordinary differential equationâconstrained (optimal) control problems and distributed partial differential equation (PDE) constrained control problems, boundary control problems with PDE state dynamics may be formally treated by the Pontryagin's maximum principle or canonical system formalism (state and adjoint PDEs).
These problems may have multiple (locally) optimal solutions; a first overview of suitable choices can be obtained by identifying canonical steady states.
The computation of canonical paths toward some optimal steady state yields temporal information about the optimal harvesting, possibly including waiting time behavior for the stock to recover from a lowâstock initial state, and nonmonotonic (in time) harvesting efforts.
Multispecies fishery models may lead to asymmetric effects; for instance, it may be optimal to capture a predator species to protect the prey, even for high costs and low market values of the predators
Review of high-contrast imaging systems for current and future ground- and space-based telescopes I. Coronagraph design methods and optical performance metrics
The Optimal Optical Coronagraph (OOC) Workshop at the Lorentz Center in
September 2017 in Leiden, the Netherlands gathered a diverse group of 25
researchers working on exoplanet instrumentation to stimulate the emergence and
sharing of new ideas. In this first installment of a series of three papers
summarizing the outcomes of the OOC workshop, we present an overview of design
methods and optical performance metrics developed for coronagraph instruments.
The design and optimization of coronagraphs for future telescopes has
progressed rapidly over the past several years in the context of space mission
studies for Exo-C, WFIRST, HabEx, and LUVOIR as well as ground-based
telescopes. Design tools have been developed at several institutions to
optimize a variety of coronagraph mask types. We aim to give a broad overview
of the approaches used, examples of their utility, and provide the optimization
tools to the community. Though it is clear that the basic function of
coronagraphs is to suppress starlight while maintaining light from off-axis
sources, our community lacks a general set of standard performance metrics that
apply to both detecting and characterizing exoplanets. The attendees of the OOC
workshop agreed that it would benefit our community to clearly define
quantities for comparing the performance of coronagraph designs and systems.
Therefore, we also present a set of metrics that may be applied to theoretical
designs, testbeds, and deployed instruments. We show how these quantities may
be used to easily relate the basic properties of the optical instrument to the
detection significance of the given point source in the presence of realistic
noise.Comment: To appear in Proceedings of the SPIE, vol. 1069
The ethos of physical activity delivery in mental health: a narrative study of service user experiences.
Our research into the physical activity experiences of people with severe mental illness has led us to take seriously the social and cultural environment in which physical activity is delivered. In this study, through narrative methodology, we examine service user accounts of physical activity to illuminate the characteristics of physical activity groups that are experienced as positive, helpful, or beneficial. We present several qualities and show how effective leadership and coaching is central to these qualities being present. We conclude that it is not so much what activity is delivered, but how it is delivered that is critical for sustained participation and positive outcomes
Testing the Limits of AGN Feedback and the Onset of Thermal Instability in the Most Rapidly Star-forming Brightest Cluster Galaxies
We present new, deep, narrow- and broadband Hubble Space Telescope observations of seven of the most star-forming brightest cluster galaxies (BCGs). Continuum-subtracted [OII] maps reveal the detailed, complex structure of warm (T ~ 104 K) ionized gas filaments in these BCGs, allowing us to measure spatially resolved star formation rates (SFRs) of ~60-600 M âyr-1. We compare the SFRs in these systems and others from the literature to their intracluster medium cooling rates ( ), measured from archival Chandra X-ray data, finding a best-fit relation of + (-3.22 ± 0.38) with an intrinsic scatter of 0.39 ± 0.09 dex. This steeper-than-unity slope implies an increasingly efficient conversion of hot (T ~ 107 K) gas into young stars with increasing , or conversely a gradual decrease in the effectiveness of AGN feedback in the strongest cool cores. We also seek to understand the physical extent of these multiphase filaments that we observe in cluster cores. We show, for the first time, that the average extent of the multiphase gas is always smaller than the radii at which the cooling time reaches 1 Gyr, the t cool/t ff profile flattens, and that X-ray cavities are observed. This implies a close connection between the multiphase filaments, the thermodynamics of the cooling core, and the dynamics of X-ray bubbles. Interestingly, we find a one-to-one correlation between the average extent of cool multiphase filaments and the radius at which the cooling time reaches 0.5 Gyr, which may be indicative of a universal condensation timescale in cluster core
Theoretical studies of the historical development of the accounting discipline: a review and evidence
Many existing studies of the development of accounting thought have either been atheoretical or have adopted Kuhn's model of scientific growth. The limitations of this 35-year-old model are discussed. Four different general neo-Kuhnian models of scholarly knowledge development are reviewed and compared with reference to an analytical matrix. The models are found to be mutually consistent, with each focusing on a different aspect of development. A composite model is proposed. Based on a hand-crafted database, author co-citation analysis is used to map empirically the entire literature structure of the accounting discipline during two consecutive time periods, 1972â81 and 1982â90. The changing structure of the accounting literature is interpreted using the proposed composite model of scholarly knowledge development
Wool and meat genetics - the joint possibilities
Wool and meat contribute to profit in sheep enterprises and both need to be considered in breeding programs. The relative responses expected from selection for a range of traits are presented and the realised responses that have been achieved in Merinos and variation in maternal breeds are illustrated. Knowledge of genetic parameters is required for the development of complex breeding objectives and selection indexes, comprehensive genetic evaluation of animals and the design of effective breeding programs. A review of world literature has highlighted the lack of accurate estimates of genetic parameters, especially for genetic correlations between trait groups. Analyses of a combined dataset from seven Australian Merino resource flocks comprising over 2000 sires and up to 100,000 records for each of various traits have provided accurate estimates of parameters to fill these gaps in current knowledge. The results show that there are no major genetic antagonisms between wool and meat traits and that improvement of both can be achieved by using appropriate selection indexes. Sheep Genetics Australia now provides a common system for genetic evaluation of Australian sheep, including across-flock estimated breeding values for a comprehensive range of traits and several standard indexes for various wool and meat breeding objectives
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