15,992 research outputs found
Production of in electron positron collisions
is an atom of simple hydrogenlike structure similar to
positronium and . In this paper energy levels and
decay widths of different decay channels of are given. Cross
section of production of this atomic system in annihilation taking
into account radiative corrections is calculated. According to our estimates
886 atoms may be produced at BEPCII and 29
atoms are produced at VEPP-4M under the present experimental
conditions.Comment: 5 pages, submitted to Int. Jour. Mod. Phys.
Maternal and fetal risk factors for stillbirth : population based study
Objective: To assess the main risk factors associated with stillbirth in a multiethnic English maternity population.
Design: Cohort study.
Setting: National Health Service region in England.
Population: 92 218 normally formed singletons including 389 stillbirths from 24 weeks of gestation, delivered during 2009-11.
Main outcome measure: Risk of stillbirth.
Results: Multivariable analysis identified a significant risk of stillbirth for parity (para 0 and para ≥3), ethnicity (African, African-Caribbean, Indian, and Pakistani), maternal obesity (body mass index ≥30), smoking, pre-existing diabetes, and history of mental health problems, antepartum haemorrhage, and fetal growth restriction (birth weight below 10th customised birthweight centile). As potentially modifiable risk factors, maternal obesity, smoking in pregnancy, and fetal growth restriction together accounted for 56.1% of the stillbirths. Presence of fetal growth restriction constituted the highest risk, and this applied to pregnancies where mothers did not smoke (adjusted relative risk 7.8, 95% confidence interval 6.6 to 10.9), did smoke (5.7, 3.6 to 10.9), and were exposed to passive smoke only (10.0, 6.6 to 15.8). Fetal growth restriction also had the largest population attributable risk for stillbirth and was fivefold greater if it was not detected antenatally than when it was (32.0% v 6.2%). In total, 195 of the 389 stillbirths in this cohort had fetal growth restriction, but in 160 (82%) it had not been detected antenatally. Antenatal recognition of fetal growth restriction resulted in delivery 10 days earlier than when it was not detected: median 270 (interquartile range 261-279) days v 280 (interquartile range 273-287) days. The overall stillbirth rate (per 1000 births) was 4.2, but only 2.4 in pregnancies without fetal growth restriction, increasing to 9.7 with antenatally detected fetal growth restriction and 19.8 when it was not detected.
Conclusion: Most normally formed singleton stillbirths are potentially avoidable. The single largest risk factor is unrecognised fetal growth restriction, and preventive strategies need to focus on improving antenatal detection
Gauge Transformations, BRST Cohomology and Wigner's Little Group
We discuss the (dual-)gauge transformations and BRST cohomology for the two
(1 + 1)-dimensional (2D) free Abelian one-form and four (3 + 1)-dimensional
(4D) free Abelian 2-form gauge theories by exploiting the (co-)BRST symmetries
(and their corresponding generators) for the Lagrangian densities of these
theories. For the 4D free 2-form gauge theory, we show that the changes on the
antisymmetric polarization tensor e^{\mu\nu} (k) due to (i) the (dual-)gauge
transformations corresponding to the internal symmetry group, and (ii) the
translation subgroup T(2) of the Wigner's little group, are connected with
each-other for the specific relationships among the parameters of these
transformation groups. In the language of BRST cohomology defined w.r.t. the
conserved and nilpotent (co-)BRST charges, the (dual-)gauge transformed states
turn out to be the sum of the original state and the (co-)BRST exact states. We
comment on (i) the quasi-topological nature of the 4D free 2-form gauge theory
from the degrees of freedom count on e^{\mu\nu} (k), and (ii) the Wigner's
little group and the BRST cohomology for the 2D one-form gauge theory {\it
vis-{\`a}-vis} our analysis for the 4D 2-form gauge theory.Comment: LaTeX file, 29 pages, misprints in (3.7), (3.8), (3.9), (3.13) and
(4.14)corrected and communicated to IJMPA as ``Erratum'
Geometrical Aspects Of BRST Cohomology In Augmented Superfield Formalism
In the framework of augmented superfield approach, we provide the geometrical
origin and interpretation for the nilpotent (anti-)BRST charges, (anti-)co-BRST
charges and a non-nilpotent bosonic charge. Together, these local and conserved
charges turn out to be responsible for a clear and cogent definition of the
Hodge decomposition theorem in the quantum Hilbert space of states. The above
charges owe their origin to the de Rham cohomological operators of differential
geometry which are found to be at the heart of some of the key concepts
associated with the interacting gauge theories. For our present review, we
choose the two -dimensional (2D) quantum electrodynamics (QED) as a
prototype field theoretical model to derive all the nilpotent symmetries for
all the fields present in this interacting gauge theory in the framework of
augmented superfield formulation and show that this theory is a {\it unique}
example of an interacting gauge theory which provides a tractable field
theoretical model for the Hodge theory.Comment: LaTeX file, 25 pages, Ref. [49] updated, correct page numbers of the
Journal are give
Nilpotent Symmetries For Matter Fields In Non-Abelian Gauge Theory: Augmented Superfield Formalism
In the framework of superfield approach to Becchi-Rouet-Stora-Tyutin (BRST)
formalism, the derivation of the (anti-)BRST nilpotent symmetries for the
matter fields, present in any arbitrary interacting gauge theory, has been a
long-standing problem. In our present investigation, the local, covariant,
continuous and off-shell nilpotent (anti-)BRST symmetry transformations for the
Dirac fields are derived in the framework of the augmented
superfield formulation where the four -dimensional (4D) interacting
non-Abelian gauge theory is considered on the six -dimensional
supermanifold parametrized by the four even spacetime coordinates and a
couple of odd elements ( and ) of the Grassmann algebra.
The requirement of the invariance of the matter (super)currents and the
horizontality condition on the (super)manifolds leads to the derivation of the
nilpotent symmetries for the matter fields as well as the gauge- and the
(anti-)ghost fields of the theory in the general scheme of the augmented
superfield formalism.Comment: LaTeX file, 16 pages, printing mistakes in the second paragraph of
`Introduction' corrected, a footnote added, these modifications submitted as
``erratum'' to IJMPA in the final for
The Myth about Universal Higher Education: Russia in the International Context
This is the final version. Available from the National Research University Higher School of Economics (HSE) via the DOI in this recordIt is widely believed that higher education in Russia has become almost universal and more people go to universities compared to most European countries. In this paper we explore this issue empirically with the Russian and European census data and data from the Trajectories in Education and Careers (TREC), a longitudinal cohort study. According to the 2010 census, only 34% of people aged between 25 and 34 in Russia have university degrees, which is nearly the same as in most Eastern European countries and slightly fewer than in Western Europe. The TREC data show that only about 50% of 2012 ninthgrade graduates were university students in 2015. The expansion of higher education in Russia has been in line with the overall European trends. Similar to other countries, there have been changes to the gender composition of university students in Russia over the last two decades, with girls being more likely to attend university than boys. The analysis of social backgrounds of students with different educational trajectories reveals a considerable social inequality within the Russian education system. Eighty-four percent of school graduates with university-educated parents are admitted to university, as compared to only 32% of children from less-educated families. Graduation from ninth grade represents an educational fork that is crucial for inequality, as children from less socially advantaged families tend to opt for vocational education at this stage. Graduation from eleventh grade is a less important educational transition: at least 80% of high school students get admitted to university after graduating from 11th grade
Magnetic and Transport Properties of Ternary Indides of type R2CoIn8 (R = Ce, Pr and Dy)
We have synthesized and investigated the magnetic and transport properties of
a series of compounds, R2CoIn8 (R = rare earth). Compounds form in single phase
with a tetragonal structure (space group P4/mmm, no. 162). The Ce compound
shows heavy fermion behavior. The magnetic susceptibility of Pr2CoIn8 shows a
marked deviation from the Curie-Weiss behavior at low temperatures, which is
attributed to the crystalline electric field effects. Heat capacity and
magnetization measurements show that Dy2CoIn8 undergoes a magnetic transition
at 17 K and a second transition near 5 K, the latter of which may be due to
spin reorientation. Magnetization of this compound shows two metamagnetic
transitions approximately at 3.6 T and 8.3 T.Comment: Total 7 pages of text and figure
Eigenvalue spectrum for single particle in a spheroidal cavity: A Semiclassical approach
Following the semiclassical formalism of Strutinsky et al., we have obtained
the complete eigenvalue spectrum for a particle enclosed in an infinitely high
spheroidal cavity. Our spheroidal trace formula also reproduces the results of
a spherical billiard in the limit . Inclusion of repetition of each
family of the orbits with reference to the largest one significantly improves
the eigenvalues of sphere and an exact comparison with the quantum mechanical
results is observed upto the second decimal place for . The
contributions of the equatorial, the planar (in the axis of symmetry plane) and
the non-planar(3-Dimensional) orbits are obtained from the same trace formula
by using the appropriate conditions. The resulting eigenvalues compare very
well with the quantum mechanical eigenvalues at normal deformation. It is
interesting that the partial sum of equatorial orbits leads to eigenvalues with
maximum angular momentum projection, while the summing of planar orbits leads
to eigenvalues with except for L=1. The remaining quantum mechanical
eigenvalues are observed to arise from the 3-dimensional(3D) orbits. Very few
spurious eigenvalues arise in these partial sums. This result establishes the
important role of 3D orbits even at normal deformations.Comment: 17 pages, 7 ps figure
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