19,586 research outputs found
Decuplet baryon magnetic moments in a QCD-based quark model beyond quenched approximation
We study the decuplet baryon magnetic moments in a QCD-based quark model
beyond quenched approximation. Our approach for unquenching the theory is based
on the heavy baryon perturbation theory in which the axial couplings for baryon
- meson and the meson-meson-photon couplings from the chiral perturbation
theory are used together with the QM moment couplings. It also involves the
introduction of a form factor characterizing the structure of baryons
considered as composite particles. Using the parameters obtained from fitting
the octet baryon magnetic moments, we predict the decuplet baryon magnetic
moments. The magnetic moment is found to be in good agreement with
experiment: is predicted to be compared to the
experimental result of (2.02 0.05) .Comment: 19 pages, 2 figure
Quality-based Multimodal Classification Using Tree-Structured Sparsity
Recent studies have demonstrated advantages of information fusion based on
sparsity models for multimodal classification. Among several sparsity models,
tree-structured sparsity provides a flexible framework for extraction of
cross-correlated information from different sources and for enforcing group
sparsity at multiple granularities. However, the existing algorithm only solves
an approximated version of the cost functional and the resulting solution is
not necessarily sparse at group levels. This paper reformulates the
tree-structured sparse model for multimodal classification task. An accelerated
proximal algorithm is proposed to solve the optimization problem, which is an
efficient tool for feature-level fusion among either homogeneous or
heterogeneous sources of information. In addition, a (fuzzy-set-theoretic)
possibilistic scheme is proposed to weight the available modalities, based on
their respective reliability, in a joint optimization problem for finding the
sparsity codes. This approach provides a general framework for quality-based
fusion that offers added robustness to several sparsity-based multimodal
classification algorithms. To demonstrate their efficacy, the proposed methods
are evaluated on three different applications - multiview face recognition,
multimodal face recognition, and target classification.Comment: To Appear in 2014 IEEE Conference on Computer Vision and Pattern
Recognition (CVPR 2014
Enskog Theory for Polydisperse Granular Mixtures II. Sonine Polynomial Approximation
The linear integral equations defining the Navier-Stokes (NS) transport
coefficients for polydisperse granular mixtures of smooth inelastic hard disks
or spheres are solved by using the leading terms in a Sonine polynomial
expansion. Explicit expressions for all the NS transport coefficients are given
in terms of the sizes, masses, compositions, density and restitution
coefficients. In addition, the cooling rate is also evaluated to first order in
the gradients. The results hold for arbitrary degree of inelasticity and are
not limited to specific values of the parameters of the mixture. Finally, a
detailed comparison between the derivation of the current theory and previous
theories for mixtures is made, with attention paid to the implication of the
various treatments employed to date.Comment: 26 pages, to be published in Phys. Rev.
TDIR: Time-Delay Interferometric Ranging for Space-Borne Gravitational-Wave Detectors
Space-borne interferometric gravitational-wave detectors, sensitive in the
low-frequency (mHz) band, will fly in the next decade. In these detectors, the
spacecraft-to-spacecraft light-travel times will necessarily be unequal and
time-varying, and (because of aberration) will have different values on up- and
down-links. In such unequal-armlength interferometers, laser phase noise will
be canceled by taking linear combinations of the laser-phase observables
measured between pairs of spacecraft, appropriately time-shifted by the light
propagation times along the corresponding arms. This procedure, known as
time-delay interferometry (TDI), requires an accurate knowledge of the
light-time delays as functions of time. Here we propose a high-accuracy
technique to estimate these time delays and study its use in the context of the
Laser Interferometer Space Antenna (LISA) mission. We refer to this ranging
technique, which relies on the TDI combinations themselves, as Time-Delay
Interferometric Ranging (TDIR). For every TDI combination, we show that, by
minimizing the rms power in that combination (averaged over integration times
s) with respect to the time-delay parameters, we obtain estimates
of the time delays accurate enough to cancel laser noise to a level well below
the secondary noises. Thus TDIR allows the implementation of TDI without the
use of dedicated inter-spacecraft ranging systems, with a potential
simplification of the LISA design. In this paper we define the TDIR procedure
formally, and we characterize its expected performance via simulations with the
\textit{Synthetic LISA} software package.Comment: 5 pages, 2 figure
A homoleptic phosphine adduct of Tl(I)
A homoleptic phosphine adduct of thallium(I) supported by a tris(phosphino)borate ligand has been isolated and structurally characterized
Kepler Mission Stellar and Instrument Noise Properties Revisited
An earlier study of the Kepler Mission noise properties on time scales of
primary relevance to detection of exoplanet transits found that higher than
expected noise followed to a large extent from the stars, rather than
instrument or data analysis performance. The earlier study over the first six
quarters of Kepler data is extended to the full four years ultimately
comprising the mission. Efforts to improve the pipeline data analysis have been
successful in reducing noise levels modestly as evidenced by smaller values
derived from the current data products. The new analyses of noise properties on
transit time scales show significant changes in the component attributed to
instrument and data analysis, with essentially no change in the inferred
stellar noise. We also extend the analyses to time scales of several days,
instead of several hours to better sample stellar noise that follows from
magnetic activity. On the longer time scale there is a shift in stellar noise
for solar-type stars to smaller values in comparison to solar values.Comment: 10 pages, 8 figures, accepted by A
Electromagnetic Moments of the Baryon Decuplet
We compute the leading contributions to the magnetic dipole and electric
quadrupole moments of the baryon decuplet in chiral perturbation theory. The
measured value for the magnetic moment of the is used to determine
the local counterterm for the magnetic moments. We compare the chiral
perturbation theory predictions for the magnetic moments of the decuplet with
those of the baryon octet and find reasonable agreement with the predictions of
the large-- limit of QCD. The leading contribution to the quadrupole
moment of the and other members of the decuplet comes from one--loop
graphs. The pionic contribution is shown to be proportional to (and so
will not contribute to the quadrupole moment of nuclei), while the
contribution from kaons has both isovector and isoscalar components. The chiral
logarithmic enhancement of both pion and kaon loops has a coefficient that
vanishes in the limit. The third allowed moment, the magnetic octupole,
is shown to be dominated by a local counterterm with corrections arising at two
loops. We briefly mention the strange counterparts of these moments.Comment: Uses harvmac.tex, 15 pages with 3 PostScript figures packed using
uufiles. UCSD/PTH 93-22, QUSTH-93-05, Duke-TH-93-5
PHOENIX: Public Health and Obesity in England – the New Infrastructure eXamined First interim report: the scoping review
The PHOENIX project aims to examine the impact of structural changes to the health and care system in England on the functioning of the public health system, and on the approaches taken to improving the public’s health.
The scoping review has now been completed. During this phase we analysed: Department of Health policy documents (2010-2013), as well as responses to those documents from a range of stakeholders; data from 22 semi-structured interviews with key informants; and the oral and written evidence presented at the House of Commons Communities and Local Government Committee on the role of local authorities in health issues. We also gathered data from local authority (LA) and Health and Wellbeing Board (HWB) websites and other sources to start to develop a picture of how the new structures are developing, and to collate demographic and other data on local authorities. A number of important themes were identified and explored during this phase. In summary, some key points related to three themes - governance, relationships and new ways of working - were:
The reforms have had a profound effect on leadership within the public health system. Whilst LAs are now the local leaders for public health, in a more fragmented system, leadership for public health appears to be more dispersed amongst a range of organisations and a range of people within the LA. At national level, the leadership role is complex and not yet developed (from a local perspective).
Accountability mechanisms have changed dramatically within public health, and many people still seem to be unclear about them. Some performance management mechanisms have disappeared, and much accountability now appears to rely on transparency and the democratic accountability that this would (theoretically) enable.
The extent to which ‘system leaders’ within PHE are able to influence local decisions and performance will depend on the strength of relationships principally between the LA and the local Public Health England centre. These relationships will take time to develop.
Many people have faced new ways of working, in new settings, and with new relationships to build. Public health teams in LAs have faced the most profound of these changes, having gone from a position of ‘expert voice’ to a position where they must defend their opinions and activities in the context of competing demands and severely restricted resources. Public health staff may require new skills, and may need to seek new ‘allies’ to thrive in the new environment.
HWBs could be crucial in bringing together a fragmented system and dispersed leadership.
The next phase of data collection will begin in March with the initiation of case study work. National surveys will be conducted in June/July this year (2014), and at the same time the following year. In this work, we will further explore the following themes: relationships, governance, decision making, new ways of working, and opportunities and difficulties
- …