665 research outputs found
Magnetic structures in the heliosheath
We propose a solitary wave model for small scale magnetic structures observed in the solar wind and more recently in the Voyager 1 observations of the heliosheath. The model is based on the recent, fully nonlinear theory of solitary waves by McKenzie et al. (2001, 2004). Our solutions i.e., magnetic holes, humps, trains of holes and humps, are strongly nonlinear (70 to 80% change in the magnetic field at the centre), propagate at large angles (>60°) to the mean magnetic field and are well approximated by Gaussians. The structures are almost pressure balanced with an anti-correlation between the magnetic field and the plasma density, and no change in the magnetic vector across the structure. These features are consistent with observations of magnetic structures in the heliosheath
Experimental Hamiltonian Identification for Qubits subject to Multiple Independent Control Mechanisms
We consider a qubit subject to various independent control mechanisms and
present a general strategy to identify both the internal Hamiltonian and the
interaction Hamiltonian for each control mechanism, relying only on a single,
fixed readout process such as measurements.Comment: submitted to Proceedings of the QCMC04 (4 pages RevTeX, 5 figures
ASASSN-14dq: A fast-declining type II-P Supernova in a low-luminosity host galaxy
Optical broadband (UBVRI) photometric and low-resolution spectroscopic
observations of the type II-P supernova (SN) ASASSN-14dq are presented.
ASASSN-14dq exploded in a low-luminosity/metallicity host galaxy UGC 11860, the
signatures of which are present as weak iron lines in the photospheric phase
spectra. The SN has a plateau duration of 90 d, with a plateau decline
rate of 1.38 in V-band which is higher than most type
II-P SNe. ASASSN-14dq is a luminous type II-P SN with a peak -band absolute
magnitude of -17.70.2 mag. The light curve of ASASSN-14dq indicates it
to be a fast-declining type II-P SN, making it a transitional event between the
type II-P and II-L SNe. The empirical relation between the steepness parameter
and mass for type II SNe was rebuilt with the help of
well-sampled light curves from the literature. A mass of
0.029 M was estimated for ASASSN-14dq, which is slightly
lower than the expected mass for a luminous type II-P SN. Using
analytical light curve modelling, a progenitor radius of cm, an ejecta mass of and a total
energy of ergs was estimated for this event. The
photospheric velocity evolution of ASASSN-14dq resembles a type II-P SN, but
the Balmer features (H and H) show relatively slow velocity
evolution. The high-velocity H feature in the plateau phase, the
asymmetric H emission line profile in the nebular phase and the
inferred outburst parameters indicate an interaction of the SN ejecta with the
circumstellar material (CSM).Comment: 28 pages, 29 figures, Accepted in MNRA
Testicular toxicity induced by T-2 toxin and protective effect of vitamin E in Wistar rats
Background and purpose: Mycotoxicosis is a very common problem in stored feed and fodder. Ingestion of T-2 toxin through feedstuff leads to serious consequences and production losses in exposed populations. That may lead to reproductive organ system damage resulting in the reproductive problem. The study was planned to investigate the effect of T-2 toxin and vitamin E on testicular function in Wistar rats.
Material and methods: Male Wistar rats were fed with standard rat feed. T-2 toxin treatment groups received T-2 toxin (2.5 ppm and 5.0 ppm) mixed feed, while vitamin E (100 mg/kg) was given by oral gavage alone and in T-2 toxin fed groups. After completion of 28 days of oral feeding of text compounds reproductive toxicity parameters were evaluated.
Results: Total live sperm counts, sperm motility, and serum testosterone levels were reduced in T-2 toxin-treated groups. Antioxidant enzymes/nonenzymes and oxidative stress indicators were altered significantly and cellular damage to testis and epididymis in T-2 toxin groups was in a dosedependent manner. However, vitamin E intervention caused a marked reversal effect in T-2 toxin-fed rats on testicular damage and male reproductive parameters. Oxidative stress and related events appear to be a potential mechanism involved in T-2 toxin-mediated testicular damage.
Conclusion: This study validated that the use of an optimum dose of vitamin E has the potential to protect against the testicular damage caused by the T-2 toxin
Instability of the heliopause driven by charge exchange interactions
The stability of the heliopause that separates the tenuous hot magnetized heliosheath plasma from the dense cool local interstellar magnetized plasma is examined using a fully general model that includes all the essential physical processes. Charge exchange coupling between plasma protons and primary interstellar neutral atoms provides an effective gravity that drives Rayleigh-Taylor (RT)-like instabilities. The velocity difference or shear between the heliosheath and interstellar flows, when coupled to energetic neutral atoms (ENAs), drives a Kelvin-Helmholtz (KH)-like instability on the heliopause. The shoulder region of the heliopause is unstable to a new instability that has characteristics of a mixed RT-KH-like mode. The instabilities are not stabilized by typical values of the magnetic fields in the inner and outer heliosheath (OHS). ENAs play an essential role in driving the KH-like instability, which is fully stabilized in their absence by magnetic fields. The nonlinear phase of these instabilities is briefly discussed. We also discuss the possibility that RT-like or mixed KH-RT-like instabilities drag outer heliosheath/very local interstellar medium (OHS/VLISM) magnetic field lines into the inner heliosheath (IHS) with the VLISM flow, and the possibility that IHS and VLISM magnetic field lines experience reconnection. Such reconnection may (1) greatly enhance the mixing of plasmas across the heliopause and (2) provide open magnetic field lines that allow easy ingress of galactic cosmic rays into the heliosphere and corresponding easy loss of anomalous cosmic rays from the heliosphere
Volar plating of isolated ulna shaft fractures
Background: Dorsal plating for ulna shaft fracture is a common practice. But this is associated with hardware prominence on the dorsal subcutaneous border of ulna necessitating implant removal on later days. Volar surface of ulna is flat similar to radius volar surface with good muscle cover reducing the problem of hardware prominence. So, we wanted to study the outcome of volar plating of ulnar shaft fractures.
Methods: Ten patients satisfying our inclusion criteria underwent volar plating using volar approach between FCU and ECU and 3.5 DCP was placed on flat volar surface of ulnar shaft under thick muscle cover of FCU and FDP.
Results: Out of 10 patients, 7 were acute fractures, 2 were neglected non unions and 1was non-union with implant insitu. Bone graft was used in non-union cases. All fractures united at 6-9 month post op without any complications.
Conclusions: Isolated ulnar shaft fractures are common orthopaedic injuries. Displaced fractures require stabilization with dynamic compression plate (DCP). Application of implant on its volar aspect in distal 2/3rd fractures is easy due to flat surface and avoids complications related to hard ware prominence and subsequent need for implant removal
Waltzing binaries: Probing line-of-sight acceleration of merging compact objects with gravitational waves
Line-of-sight acceleration of a compact binary coalescence (CBC) event would
modulate the shape of the gravitational waves (GWs) it produces with respect to
the corresponding non-accelerated CBC. Such modulations could be indicative of
its astrophysical environment. We investigate the prospects of detecting this
acceleration in future observing runs of the LIGO-Virgo-KAGRA network, as well
as in next-generation (XG) detectors and the proposed DECIGO. We place the
first observational constraints on this acceleration, for putative binary
neutron star mergers GW170817 and GW190425. We find no evidence of
line-of-sight acceleration in these events at confidence. Prospective
constraints for the fifth observing run of the LIGO at A+ sensitivity suggest
that accelerations for typical BNSs could be constrained with a precision of
, assuming a signal-to-noise ratio of .
These improve to in XG detectors, and in DECIGO. We also interpret these constraints
in the context of mergers around supermassive black holes.Comment: Accepted to Ap
Exclusion of Tiny Interstellar Dust Grains from the Heliosphere
The distribution of interstellar dust grains (ISDG) observed in the Solar
System depends on the nature of the interstellar medium-solar wind interaction.
The charge of the grains couples them to the interstellar magnetic field (ISMF)
resulting in some fraction of grains being excluded from the heliosphere while
grains on the larger end of the size distribution, with gyroradii comparable to
the size of the heliosphere, penetrate the termination shock. This results in a
skewing the size distribution detected in the Solar System.
We present new calculations of grain trajectories and the resultant grain
density distribution for small ISDGs propagating through the heliosphere. We
make use of detailed heliosphere model results, using three-dimensional (3-D)
magnetohydrodynamic/kinetic models designed to match data on the shape of the
termination shock and the relative deflection of interstellar neutral H and He
flowing into the heliosphere. We find that the necessary inclination of the
ISMF relative to the inflow direction results in an asymmetry in the
distribution of the larger grains (0.1 micron) that penetrate the heliopause.
Smaller grains (0.01 micron) are completely excluded from the Solar System at
the heliopause.Comment: 5 pages, 5 figures, accepted for publication in the Solar Wind 12
conference proceeding
Axisymmetric equilibria of a gravitating plasma with incompressible flows
It is found that the ideal magnetohydrodynamic equilibrium of an axisymmetric
gravitating magnetically confined plasma with incompressible flows is governed
by a second-order elliptic differential equation for the poloidal magnetic flux
function containing five flux functions coupled with a Poisson equation for the
gravitation potential, and an algebraic relation for the pressure. This set of
equations is amenable to analytic solutions. As an application, the
magnetic-dipole static axisymmetric equilibria with vanishing poloidal plasma
currents derived recently by Krasheninnikov, Catto, and Hazeltine [Phys. Rev.
Lett. {\bf 82}, 2689 (1999)] are extended to plasmas with finite poloidal
currents, subject to gravitating forces from a massive body (a star or black
hole) and inertial forces due to incompressible sheared flows. Explicit
solutions are obtained in two regimes: (a) in the low-energy regime
, where
, , , and are related to the thermal,
poloidal-current, flow and gravitating energies normalized to the
poloidal-magnetic-field energy, respectively, and (b) in the high-energy regime
. It turns out
that in the high-energy regime all four forces, pressure-gradient,
toroidal-magnetic-field, inertial, and gravitating contribute equally to the
formation of magnetic surfaces very extended and localized about the symmetry
plane such that the resulting equilibria resemble the accretion disks in
astrophysics.Comment: 12 pages, latex, to be published in Geophys. Astrophys. Fluid
Dynamic
Evaluation of accuracy of various impression techniques and impression materials in recording multiple implants placed unilaterally in a partially edentulous mandible- An in vitro study
Various factors like implant angulation, type of impression material and tray type affects the implant impression accuracy. To date limited in-vitro studies were carried out on the implant impression accuracy of unilateral partially edentulous arches. The aim of this research was to evaluate the effects of 0o, 15o and 25o implant angulations on impression accuracy in simulated master casts of unilateral partially edentulous situation using different impression materials and tray selections. 30 replicas (N = 30) of a resin matrix (control) containing four implant analogues placed unilaterally from the midline till the region of second molar at an angulation of 00, 00, 150 and 250 to the vertical axis of the ridge respectively were obtained by using three impression techniques (stock metal tray, closed custom tray, and open nonsplinted custom tray) and two different impression materials (Polyvinyl-siloxane and polyether). Specific dimensions of the resultant casts were measured using coordinated measuring microscope. Mean linear changes were calculated and statistically analyzed using analysis of variance (ANOVA) and Tukey?s post-hoc procedures (p< 0.05). The casts obtained from all three impression techniques had significant differences in dimensions (p<0.05) as compared to that of master model irrespective of impression materials. Comparing the techniques with regard to the parallel implants, no statistical significant difference (p<0.05) was observed with custom tray techniques (closed/open). Whereas while comparing parallel versus non parallel, open tray technique showed superior accuracy compared to closed tray technique as the angulation increased more than 15 degrees. The influence of material and technique appeared to be significant for highly non axial implant angulations (p< 0.05), and increased angulation tended to decrease impression accuracy. The open tray technique was more accurate with highly nonaxially oriented implants for the small sample size investigated
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