1,813 research outputs found
Hidden symmetry in the presence of fluxes
We derive the most general first order symmetry operator for the Dirac
equation coupled to arbitrary fluxes. Such an operator is given in terms of an
inhomogenous form omega which is a solution to a coupled system of first order
partial differential equations which we call the generalized conformal
Killing-Yano system. Except trivial fluxes, solutions of this system are
subject to additional constraints. We discuss various special cases of physical
interest. In particular, we demonstrate that in the case of a Dirac operator
coupled to the skew symmetric torsion and U(1) field, the system of generalized
conformal Killing-Yano equations decouples into the homogenous conformal
Killing-Yano equations with torsion introduced in [arXiv:0905.0722] and the
symmetry operator is essentially the one derived in [arXiv:1002.3616]. We also
discuss the Dirac field coupled to a scalar potential and in the presence of
5-form and 7-form fluxes.Comment: 13 pages, no figure
The Electrodynamics of Inhomogeneous Rotating Media and the Abraham and Minkowski Tensors II: Applications
Applications of the covariant theory of drive-forms are considered for a
class of perfectly insulating media. The distinction between the notions of
"classical photons" in homogeneous bounded and unbounded stationary media and
in stationary unbounded magneto-electric media is pointed out in the context of
the Abraham, Minkowski and symmetrized Minkowski electromagnetic
stress-energy-momentum tensors. Such notions have led to intense debate about
the role of these (and other) tensors in describing electromagnetic
interactions in moving media. In order to address some of these issues for
material subject to the Minkowski constitutive relations, the propagation of
harmonic waves through homogeneous and inhomogeneous, isotropic plane-faced
slabs at rest is first considered. To motivate the subsequent analysis on
accelerating media two classes of electromagnetic modes that solve Maxwell's
equations for uniformly rotating homogeneous polarizable media are enumerated.
Finally it is shown that, under the influence of an incident monochromatic,
circularly polarized, plane electromagnetic wave, the Abraham and symmetrized
Minkowski tensors induce different time-averaged torques on a uniformly
rotating materially inhomogeneous dielectric cylinder. We suggest that this
observation may offer new avenues to explore experimentally the covariant
electrodynamics of more general accelerating media.Comment: 29 pages, 4 figures. Accepted for publication in Proc. Roy. Soc.
Training telescope operators and support astronomers at Paranal
The operations model of the Paranal Observatory relies on the work of
efficient staff to carry out all the daytime and nighttime tasks. This is
highly dependent on adequate training. The Paranal Science Operations
department (PSO) has a training group that devises a well-defined and
continuously evolving training plan for new staff, in addition to broadening
and reinforcing courses for the whole department. This paper presents the
training activities for and by PSO, including recent astronomical and quality
control training for operators, as well as adaptive optics and interferometry
training of all staff. We also present some future plans.Comment: Paper 9910-123 presented at SPIE 201
Distance to Multiple Kinematic Components of Quasar Outflows: VLT Observations of QSO 2359-1241 and SDSS J0318-0600
Using high resolution VLT spectra, we study the multi-component outflow
systems of two quasars exhibiting intrinsic Fe II absorption (QSO 2359-1241 and
SDSS J0318-0600). From the extracted ionic column densities and using
photoionization modeling we determine the gas density, total column density,
and ionization parameter for several of the components. For each object the
largest column density component is also the densest, and all other components
have densities of roughly 1/4 of that of the main component. We demonstrate
that all the absorbers lie roughly at the same distance from the source.
Further, we calculate the total kinetic luminosities and mass outflow rates of
all components and show that these quantities are dominated by the main
absorption component.Comment: 27 pages, 5 figure
Understanding Interactive Effects of Emotional Labour on Racialized Support Workers in Post-Secondary Institutions
Cet article traite de deux aidants discriminés qui travaillent ou ont déjà travaillé dans un centre de prévention de violence sexuelle à la demande d’un campus universitaire. Que veut dire cacher ses sentiments afin d’aider les survivants? Quel est l’Impact de ce travail affectif sur le travailleur social
5α-DihydroÂvespertilin acetate
In the title compound, C24H36O4 [systematic name: (20S)-3β-acetÂoxy-16α-hydrÂoxy-22,23-bisÂnor-5α,17β-cholano(22-16)lacÂtone], the three six-membered rings adopt classical chair conformations, while the five-membered rings are in envelope conformations. The ester group attached to ring A is in an equatorial position. Rings A/B, B/C and C/D are trans-fused, whereas rings D/E are cis-fused. The structure is devoid of any classical hydrogen bonds. However, non-classical inter- and intraÂmolecular hydrogen-bonding interÂactions of the type C—H⋯O are present in the structure
A randomized trial of a standard dose of Edmonston-Zagreb measles vaccine given at 4.5 months of age: effect on total hospital admissions.
Observational studies and trials from low-income countries indicate that measles vaccine has beneficial nonspecific effects, protecting against non-measles-related mortality. It is not known whether measles vaccine protects against hospital admissions. Between 2003 and 2007, 6417 children who had received the third dose of diphtheria, tetanus, and pertussis vaccine were randomly assigned to receive measles vaccine at 4.5 months or no measles vaccine; all children were offered measles vaccine at 9 months of age. Using hospital admission data from the national pediatric ward in Bissau, Guinea-Bissau, we compared admission rates between enrollment and the 9-month vaccination in Cox models, providing admission hazard rate ratios (HRRs) for measles vaccine versus no measles vaccine. All analyses were conducted stratified by sex and reception of neonatal vitamin A supplementation (NVAS). Before enrollment the 2 groups had similar admission rates. Following enrollment, the measles vaccine group had an admission HRR of 0.70 (95% confidence interval [CI], .52-.95), with a ratio of 0.53 (95% CI, .32-.86) for girls and 0.86 (95% CI, .58-1.26) for boys. For children who had not received NVAS, the admission HRR was 0.53 (95% CI, .34-.84), with an effect of 0.30 (95% CI, .13-.70) for girls and 0.73 (95% CI, .42-1.28) for boys (P = .08, interaction test). The reduction in admissions was separately significant for measles infection (admission HRR, 0 [95% CI, 0-.24]) and respiratory infections (admission HRR, 0.37 [95% CI, .16-.89]). Early measles vaccine may have major benefits for infant morbidity patterns and healthcare costs. Clinical trials registration NCT00168558
Holographic Renormalization Group with Fermions and Form Fields
We find the Holographic Renormalization Group equations for the holographic
duals of generic gravity theories coupled to form fields and spin-1/2 fermions.
Using Hamilton-Jacobi theory we discuss the structure of Ward identities,
anomalies, and the recursive equations for determining the divergent terms of
the generating functional. In particular, the Ward identity associated to
diffeomorphism invariance contains an anomalous contribution that, however, can
be solved either by a suitable counter term or by imposing a condition on the
boundary fields. Consistency conditions for the existence of the dual arise, if
one requires that a Callan-Symanzik type equation follows from the Hamiltonian
constraint. Under mild assumptions we are able to find a class of solutions to
the constraint equations. The structure of the fermionic phase space and
constraints is treated extensively for any dimension and signature.Comment: 37 pages, LaTeX; v2: Minor changes, references added; v3: End of Sec.
5 and the Appendix C removed. Final version published in Nuclear Physics
Optical Morphologies of Millijansky Radio Galaxies Observed by HST and in the VLA FIRST Survey
We report on a statistical study of the 51 radio galaxies at the millijansky
flux level from the Faint Images of the Radio Sky at Twenty centimeters,
including their optical morphologies and structure obtained with the Hubble
Space Telescope. Our optical imaging is significantly deeper (~2 mag) than
previous studies with the superior angular resolution of space-based imaging.
We that find 8/51 (16%) of the radio sources have no optically identifiable
counterpart to AB~24 mag. For the remaining 43 sources, only 25 are
sufficiently resolved in the HST images to reliably assign a visual
classification: 15 (60%) are elliptical galaxies, 2 (8%) are late-type spiral
galaxies, 1 (4%) is an S0, 3 (12%) are point-like objects (quasars), and 4
(16%) are merger systems. We find a similar distribution of optical types with
measurements of the Sersic index. The optical magnitude distribution of these
galaxies peaks at I~20.7+-0.5 AB mag, which is ~3 mag brighter than the depth
of our typical HST field and is thus not due to the WFPC2 detection limit. This
supports the luminosity-dependent density evolutionary model, where the
majority of faint radio galaxies typically have L*-optical luminosities and a
median redshift of z~0.8 with a relatively abrupt redshift cut-off at z>~2. We
discuss our results in the context of the evolution of elliptical galaxies and
active galactic nuclei.Comment: 20 pages, 8 figures, 51 galaxy images, and 5 tables. Uses
emulateapj.cls and natbib.sty. Accepted to ApJS. High resolution images are
available upon reques
Recommended from our members
Long-Term Corticosteroid-Sparing Immunosuppression for Cardiac Sarcoidosis.
Background Long-term corticosteroid therapy is the standard of care for treatment of cardiac sarcoidosis (CS). The efficacy of long-term corticosteroid-sparing immunosuppression in CS is unknown. The goal of this study was to assess the efficacy of methotrexate with or without adalimumab for long-term disease suppression in CS, and to assess recurrence and adverse event rates after immunosuppression discontinuation. Methods and Results Retrospective chart review identified treatment-naive CS patients at a single academic medical center who received corticosteroid-sparing maintenance therapy. Demographics, cardiac uptake of 18-fluorodeoxyglucose, and adverse cardiac events were compared before and during treatment and between those with persistent or interrupted immunosuppression. Twenty-eight CS patients were followed for a mean 4.1 (SD 1.5) years. Twenty-five patients received 4 to 8 weeks of high-dose prednisone (>30 mg/day), followed by taper and maintenance therapy with methotrexate±low-dose prednisone (low-dose prednisone, <10 mg/day). Adalimumab was added in 19 patients with persistently active CS or in those with intolerance to methotrexate. Methotrexate±low-dose prednisone resulted in initial reduction (88%) or elimination (60%) of 18-fluorodeoxyglucose uptake, and patients receiving adalimumab-containing regimens experienced improved (84%) or resolved (63%) 18-fluorodeoxyglucose uptake. Radiologic relapse occurred in 8 of 9 patients after immunosuppression cessation, 4 patients on methotrexate-containing regimens, and in no patients on adalimumab-containing regimens. Conclusions Corticosteroid-sparing regimens containing methotrexate with or without adalimumab is an effective maintenance therapy in patients after an initial response is confirmed. Disease recurrence in patients on and off immunosuppression support need for ongoing radiologic surveillance regardless of immunosuppression regimen
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