551 research outputs found
The Individual and Collective Effects of Exact Exchange and Dispersion Interactions on the Ab Initio Structure of Liquid Water
In this work, we report the results of a series of density functional theory
(DFT) based ab initio molecular dynamics (AIMD) simulations of ambient liquid
water using a hierarchy of exchange-correlation (XC) functionals to investigate
the individual and collective effects of exact exchange (Exx), via the PBE0
hybrid functional, non-local vdW/dispersion interactions, via a fully
self-consistent density-dependent dispersion correction, and approximate
nuclear quantum effects (aNQE), via a 30 K increase in the simulation
temperature, on the microscopic structure of liquid water. Based on these AIMD
simulations, we found that the collective inclusion of Exx, vdW, and aNQE as
resulting from a large-scale AIMD simulation of (HO) at the
PBE0+vdW level of theory, significantly softens the structure of ambient liquid
water and yields an oxygen-oxygen structure factor, , and
corresponding oxygen-oxygen radial distribution function, , that
are now in quantitative agreement with the best available experimental data.
This level of agreement between simulation and experiment as demonstrated
herein originates from an increase in the relative population of water
molecules in the interstitial region between the first and second coordination
shells, a collective reorganization in the liquid phase which is facilitated by
a weakening of the hydrogen bond strength by the use of the PBE0 hybrid XC
functional, coupled with a relative stabilization of the resultant disordered
liquid water configurations by the inclusion of non-local vdW/dispersion
interactions
Wigner's little group, gauge transformations and dimensional descent
We propose a technique called dimensional descent to show that Wigner's
little group for massless particles, which acts as a generator of gauge
transformation for usual Maxwell theory, has an identical role even for
topologically massive gauge theories. The examples of theory and
Maxwell-Chern-Simons theory are analyzed in details.Comment: LaTex, revised version shortened to 9 pages; To appear in Jour.Phys.
Neutrino masses, cosmological bound and four zero Yukawa textures
Four zero neutrino Yukawa textures in a specified weak basis, combined with
symmetry and type-I seesaw, yield a highly constrained and predictive
scheme. Two alternately viable light neutrino Majorana mass matrices
result with inverted/normal mass ordering. Neutrino
masses, Majorana in character and predicted within definite ranges with
laboratory and cosmological inputs, will have their sum probed cosmologically.
The rate for decay, though generally below the reach of
planned experiments, could approach it in some parameter region. Departure from
symmetry due to RG evolution from a high scale and consequent CP
violation, with a Jarlskog invariant whose magnitude could almost reach
, are explored.Comment: Published versio
Gauge invariances of higher derivative Maxwell-Chern-Simons field theory -- a new Hamiltonian approach
A new method of abstracting the independent gauge invariances of higher
derivative systems, recently introduced in [1], has been applied to higher
derivative field theories. This has been discussed taking the extended
Maxwell-Chern-Simons model as an example. A new Hamiltonian analysis of the
model is provided. This Hamiltonian analysis has been used to construct the
independent gauge generator. An exact mapping between the Hamiltonian gauge
transformations and the U(1) symmetries of the action has been established.Comment: 16 pages, no figure. Title and abstract modified, new references
added. This version to appear in Phys. Rev.
ASCA Observation of the New Transient X-ray Pulsar XTE J0111.2-7317 in the Small Magellanic Cloud
The new transient X-ray pulsar XTE J0111.2-7317 was observed with Advanced
Satellite for Cosmology and Astrophysics (ASCA) on 1998 November 18, a few days
after its discovery with the Proportional Counter Array onboard the Rossi X-ray
Timing Explorer. The source was detected at a flux level of 3.6x10^-10 erg
cm^-2 s^-1 in the 0.7--10.0 keV band, which corresponds to the X-ray luminosity
of 1.8x10^38 erg s^-1, if a distance of 65 kpc for this pulsar in the Small
Magellanic Cloud is assumed. Nearly sinusoidal pulsations with a period of
30.9497 +/- 0.0004 s were unambiguously detected during the ASCA observation.
The pulsed fraction is low and slightly energy dependent with average value of
\~27%. The energy spectrum shows a large soft excess below ~2 keV when fitted
to a simple power-law type model. The soft excess is eliminated if the spectrum
is fitted to an ``inversely broken power-law'' model, in which photon indices
below and above a break energy of 1.5 keV are 2.3 and 0.8, respectively. The
soft excess can also be described by a blackbody or a thermal bremsstrahlung
when the spectrum above ~2 keV is modeled by a power-law. In these models,
however, the thermal soft component requires a very large emission zone, and
hence it is difficult to explain the observed pulsations at energies below 2
keV. A bright state of the source enables us to identify a weak iron line
feature at 6.4 keV with an equivalent width of 50 +/- 14 eV. Pulse phase
resolved spectroscopy revealed a slight hardening of the spectrum and marginal
indication of an increase in the iron line strength during the pulse maximum.Comment: 8 pages, 5 Figures, to be published in ApJ. Also available at
http://www-cr.scphys.kyoto-u.ac.jp/member/jun/job
Non-commutative Quantum Mechanics in Three Dimensions and Rotational Symmetry
We generalize the formulation of non-commutative quantum mechanics to three
dimensional non-commutative space. Particular attention is paid to the
identification of the quantum Hilbert space in which the physical states of the
system are to be represented, the construction of the representation of the
rotation group on this space, the deformation of the Leibnitz rule accompanying
this representation and the implied necessity of deforming the co-product to
restore the rotation symmetry automorphism. This also implies the breaking of
rotational invariance on the level of the Schroedinger action and equation as
well as the Hamiltonian, even for rotational invariant potentials. For
rotational invariant potentials the symmetry breaking results purely from the
deformation in the sense that the commutator of the Hamiltonian and angular
momentum is proportional to the deformation.Comment: 21 page
'Mu-Tau' symmetry, tribimaximal mixing and four zero neutrino Yukawa textures
Within the type-I seesaw framework with three heavy right chiral neutrinos
and in the basis where the latter and the charged leptons are mass diagonal, a
near `mu-tau' symmetry in the neutrino sector is strongly suggested by the
neutrino oscillation data. There is further evidence for a close to the
tribimaximal mixing pattern which subsumes `mu-tau' symmetry. On the other
hand, the assumption of a (maximally allowed) four zero texture in the Yukawa
coupling matrix Y_nu in the same basis leads to a highly constrained and
predictive theoretical scheme. We show that the requirement of an exact
`mu-tau' symmetry, coupled with observational constraints, reduces the `seventy
two' allowed textures in such a `Y_nu' to 'only four' corresponding to just two
different forms of the light neutrino mass matrix `m_nu'. The effect of each of
these on measurable quantities can be described, apart from an overall factor
of the neutrino mass scale, in terms of two real parameters and a phase angle
all of which are within very constrained ranges. The additional input of a
tribimaximal mixing reduces these three parameters to `only one' with a very
nearly fixed value. Implications for both flavored and unflavored leptogenesis
as well as radiative lepton flavor violating decays are discussed. We also
investigate the stability of these conclusions under small deviations due to
renormalization group running from a high scale where the four zero texture as
well as `mu-tau' symmetry or the tribimaximal mixing pattern are imposed.Comment: Typographical changes,accepted for publication in JHE
Quality of Life among Younger Women with Breast Cancer.
INTRODUCTION:
The diagnosis of breast cancer despite improved overall survival continues to
Generate fear and turmoil in the lives of women and their families. Prevalence studies of
Psychological distress indicate that one of every three newly diagnosed patients
Experiences significant difficulty in adjustment. [1] Further evidence suggests that the
Diagnosis of breast cancer generates more anxiety than any other cancer diagnosis. [2]
At the time of diagnosis patients experience uncertainty, confusion and distress.
Psychological distress can be exacerbated by inadequate information, complex treatment
Decisions, and scheduling difficulties with various specialities. As treatment begins,
Concerns related to physical functioning, body image, mood, sexuality, family and
Vocational pursuits quickly emerge. Surgical options which include lumpectomy,
Mastectomy and reconstruction present unique issues as the patient contemplates the
Advantages and disadvantages of each procedure. Following surgery adjuvant therapy
Generates additional physiological assaults that further affect body image, sexuality and
Family life.
They require rehabilitative assistance beyond the physical domain. Major
Rehabilitation problem areas include physical, psychological, social, sexual, nutritional,
Financial and vocational ones.
For younger women the physical and psychosocial morbidity associated with
Treatments may affect their ability to successfully function in social roles that typify this
Age group. Hence we would like to study the quality of life issues in this subset.
AIMS :
1. To describe the quality of life among breast cancer women with age less than or
Equal to 35 years at the time of diagnosis.
2. To determine the contribution of socio demographic, medical and psychosocial
Factors on quality of life.
3. To study the impact of breast conservation treatment and mastectomy on the
Quality of life
Houston SHOCK: A Practical Scoring System Incorporating Cardiogenic Shock Dynamic Changes
Cardiogenic shock has an unacceptably high mortality rate and additional tools are needed to improve outcomes. The Society of Cardiovascular Angiography and Interventions (SCAI) shock severity classification has provided a unified definition of shock severity that has proven to be reproducible and predictive of survival. However, cardiogenic shock assessment goes beyond standardizing its severity, and a uniform and practical approach to comprehensive assessment that may guide therapy in a dynamic state is currently lacking.
Since cardiogenic shock is a rapidly evolving pathophysiological catastrophe, we propose a new assessment tool – the Houston SHOCK Score – which incorporates dynamic changes. The acronym SHOCK can be used to emphasize five key aspects of patients in cardiogenic shock: Severity, Hemodynamics, Onset, Causes, and Kinetics. We believe this tool provides physicians with vital information that will facilitate appropriate care by incorporating dynamic changes in the patient’s profile
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