13,564 research outputs found
Circular dichroism of magneto-phonon resonance in doped graphene
Polarization resolved, Raman scattering response due to E phonon in
monolayer graphene has been investigated in magnetic fields up to 29 T. The
hybridization of the E phonon with only the fundamental inter Landau
level excitation (involving the n=0 Landau level) is observed and only in one
of the two configurations of the circularly crossed polarized excitation and
scattered light. This polarization anisotropy of the magneto-phonon resonance
is shown to be inherent to relatively strongly doped graphene samples, with
carrier concentration typical for graphene deposited on SiO
HST Observations of the Gravitationally Lensed Cloverleaf Broad Absorption Line QSO H1413+1143: Modeling the Lens
We investigate gravitational lens models for the quadruply-lensed Cloverleaf
BAL QSO H1413+1143 based on the HST WFPC/WFPC2 astrometric and photometric data
of the system by Turnshek et al. and the HST NICMOS-2 data by Falco et al. The
accurate image positions and the dust-extinction-corrected relative
amplifications, along with a possible detection of the lensing galaxy in the
infrared, permit more accurate lens models than were previously possible. While
more recent models are qualitatively consistent with the HST data, none of the
previous models considered the dust-extinction-corrected relative
amplifications of the image components. We use the power-law elliptical mass
model to fit the HST data. We find that a single elliptical galaxy perturbed by
an external shear can fit the image positions within the observational
uncertainties; however, the predicted relative magnifications are only roughly
consistent with the observational relative amplifications. We find that a
primary galaxy combined with a secondary galaxy in the vicinity of the
Cloverleaf or a cluster centered (south-)west of the Cloverleaf can fit both
the image positions and relative amplifications within the observational
uncertainties. We discuss future observations which could be used to test
and/or further constrain lens models of the Cloverleaf.Comment: 23 pages (in aaspp.sty) including 5 tables and 3 figures, Accepted
for publication in the Astrophysical Journa
Gluon mass generation without seagull divergences
Dynamical gluon mass generation has been traditionally plagued with seagull
divergences, and all regularization procedures proposed over the years yield
finite but scheme-dependent gluon masses. In this work we show how such
divergences can be eliminated completely by virtue of a characteristic
identity, valid in dimensional regularization. The ability to trigger the
aforementioned identity hinges crucially on the particular Ansatz employed for
the three-gluon vertex entering into the Schwinger-Dyson equation governing the
gluon propagator. The use of the appropriate three-gluon vertex brings about an
additional advantage: one obtains two separate (but coupled) integral
equations, one for the effective charge and one for the gluon mass. This system
of integral equations has a unique solution, which unambiguously determines
these two quantities. Most notably, the effective charge freezes in the
infrared, and the gluon mass displays power-law running in the ultraviolet, in
agreement with earlier considerations.Comment: 37 pages, 9 figures; minor typos corrected and a few brief
explanatory remarks adde
A rare presentation of shingles (herpes zoster) in an infant
Herpes zoster (HZ) in children is very rare. We report a case of HZ in an infant which responded well to the treatment. HZ shouldalso be considered in an infant with vesiculo-bullous lesion in a dermatomal distribution
Optimizing use of empirical antibiotics in late preterm neonates at risk of early-onset sepsis
Background: In sick neonates, we are posed to treat suspected or proven infection. However, the vast majority of newborn babies who are given antibiotics do not have any infection. Objective: The objective of this study was to optimize the use of empirical antibiotic therapy in late preterms who are asymptomatic with maternal risk and symptomatic neonates without maternal risk for early-onset sepsis (EOS) and to estimate the rate of risk increase in onset of symptoms in neonates exposed to maternal risk factor for EOS. Methods: In this descriptive study, late preterm neonates (34+0–36+6 weeks) who are asymptomatic at birth with and without maternal risk factor for EOS at birth were subjected to clinical assessment of sensorium, temperature, oxygenation status, perfusion, and skin color, starting after 1 h of initial stabilization till discharge from hospital. Sepsis screen (C-reactive protein and absolute neutrophil count) was obtained at 24 h and 48 h of age from these asymptomatic late preterms. Results: A total of 135 late preterm neonates (34+0–36+6 weeks) recruited during the study period were included for analysis. The presence of maternal risk factor for EOS has shown no statistical significance in relation to the presence of symptoms at birth odds ratio 0.66, 95% confident interval (0.24–1.8) p=0.42. Conclusion: In our study, as maternal risk factor for sepsis has shown no statistical significance in relation to the presence of symptoms at birth, antibiotic use can be restricted to only those babies who have clinical worsening over 24–48 h of observation and/or along with supportive evidence of positive sepsis screen and/or blood culture, irrespective of the presence or absence of maternal risk for EOS
Constant magnetic field and 2d non-commutative inverted oscillator
We consider a two-dimensional non-commutative inverted oscillator in the
presence of a constant magnetic field, coupled to the system in a
``symplectic'' and ``Poisson'' way. We show that it has a discrete energy
spectrum for some value of the magnetic field.Comment: 7 pages, LaTeX file, no figures, PACS number: 03.65.-
Congenital dislocation of knee: A correctable deformity
We report the case of a late preterm small for gestational age baby girl presenting with deformities of both knees at birth. Diagnosisby radiologic investigation revealed bilateral knee joint dislocation and ultrasonography revealed developmental dysplasia of thehip. Concomitant treatment of the congenital dislocation of the knee with serial casting and the hip with Pavlik harness providedsatisfactory results. Cases with delayed presentation or which do not respond to conservative treatment need surgery. Delay intreatment may lead to long-term instability and stiffness. Emphasis should be laid on the immediate recognition and treatment ofthe condition
Internal water bridge and antiparallel sheet in the structure of benzyloxycarbonyl-L-alanyl-D-phenylalanyl-L-proline monohydrate
Benzyloxycarbonyl-L-alanyl-o-phenylalanyl-L-proline monohydrate, C25H29N3O6.H2O, crystallizes in the orthorhombic space group P212121 with four molecules in a unit cell of dimensions a = 9.594 (9), b = 9.705 (4) and c = 27.9 17 (12) Å. The structure has been refined to an R value of 0.067 for 2046 observed reflections. All the peptide units in the molecule are trans and the prolyl residue is in the conformation. The lone water molecule in the structure is hydrogen bonded to the carbonyl O atom in the C2 - Cγ - exo - Cβ endo conformation. The lone water molecule in the structure is hydrogen bonded to the carbonyl O atom in the benzyloxycarbonyl group and to one of the O atoms in the terminal carboxyl group. This internal water bridge, observed for the first time in a linear peptide, provides a model for water-mediated chain-reversal. An interesting feature of the crystal structure is the presence of an antiparallel sheet involving the alanyl and the phenyl-alanyl residues
A multipole-Taylor expansion for the potential of gravitational lens MG J0414+0534
We employ a multipole-Taylor expansion to investigate how tightly the
gravitational potential of the quadruple-image lens MG J0414+0534 is
constrained by recent VLBI observations. These observations revealed that each
of the four images of the background radio source contains four distinct
components, thereby providing more numerous and more precise constraints on the
lens potential than were previously available. We expand the two-dimensional
lens potential using multipoles for the angular coordinate and a modified
Taylor series for the radial coordinate. After discussing the physical
significance of each term, we compute models of MG J0414+0534 using only VLBI
positions as constraints. The best-fit model has both interior and exterior
quadrupole moments as well as exterior m=3 and m=4 multipole moments. The
deflector centroid in the models matches the optical galaxy position, and the
quadrupoles are aligned with the optical isophotes. The radial distribution of
mass could not be well constrained. We discuss the implications of these models
for the deflector mass distribution and for the predicted time delays between
lensed components.Comment: 44 pages, 5 figures, 11 tables, accepted for publication in Ap
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