571 research outputs found
Evolution of Crustal Magnetic Fields in Isolated Neutron Stars : Combined Effects of Cooling and Curvature of Space-time
The ohmic decay of magnetic fields confined within the crust of neutron stars
is considered by incorporating both the effect of neutron star cooling and the
effect of space-time curvature produced by the intense gravitational field of
the star. For this purpose a stationary and static gravitational field has been
considered with the standard as well as the accelerated cooling models of
neutron stars. It is shown that general relativistic effect reduces the
magnetic field decay rate substantially. At the late stage of evolution when
the field decay is mainly determined by the impurity-electron scattering, the
effect of space-time curvature suppresses the role of the impurity content
significantly and reduces the decay rate by more than an order of magnitude.
Even with a high impurity content the decay rate is too low to be of
observational interest if the accelerated cooling model along with the effect
of space-time curvature is taken into account. It is, therefore, pointed out
that if a decrease in the magnetic field strength by more than two orders of
magnitude from its initial value is detected by observation then the existence
of quark in the core of the neutron star would possibly be ruled out.Comment: 15 pages, AAS LATEX macros v4.0, 5 postscript figures, Accepted for
publication in the Astrophysical Journal (Part I
On the problem of novel composite materials development for car brake rotor
This paper presents a study of the potential materials that are suitable for the development of the automotive brake disc. Two new materials are proposed as an alternative material to the conventionally used gray cast iron for the disc brake, which are namely Metal Matrix Composite (MMC) and Functionally Graded Material (FGM). MMCs with ceramic particulate reinforcement are found to have a low density and high thermal conductivity compared to the cast irons. Two particulate reinforcements, Al2O3 and SiC were being considered for MMC. On the other hand, FGM has demonstrated high thermal shock resistance, better wear resistance and low density. Preliminary investigation indicated that MMC acquired improved hardness property. Meanwhile, the hardness property of FGM with Al2O3 and Al2TiO5 as layered composites materials can be further improved
How can health care organisations make and justify decisions about risk reduction? Lessons from a cross-industry review and a health care stakeholder consensus development process
Interventions to reduce risk often have an associated cost. In UK industries decisions about risk reduction are made and justified within a shared regulatory framework that requires that risk be reduced as low as reasonably practicable. In health care no such regulatory framework exists, and the practice of making decisions about risk reduction is varied and lacks transparency. Can health care organisations learn from relevant industry experiences about making and justifying risk reduction decisions? This paper presents lessons from a qualitative study undertaken with 21 participants from five industries about how such decisions are made and justified in UK industry. Recommendations were developed based on a consensus development exercise undertaken with 20 health care stakeholders. The paper argues that there is a need in health care to develop a regulatory framework and an agreed process for managing explicitly the trade-off between risk reduction and cost. The framework should include guidance about a health care specific notion of acceptable levels of risk, guidance about standardised risk reduction interventions, it should include regulatory incentives for health care organisations to reduce risk, and it should encourage the adoption of an approach for documenting explicitly an organisation’s risk position
Experimental Error Performance of Modulation Schemes Under a Controlled Laboratory Turbulence FSO Channel
This paper experimentally investigates the performance of different modulation schemes under the atmospheric turbulence conditions for free space optical communication links. The experiments were carried out in a dedicated and controlled indoor atmospheric chamber. The turbulence environment was created by introducing hot air, while the temperature profile was monitored throughout the chamber to maintain a constant environment. By evaluating the error performance of different modulation schemes under identical conditions, it was observed that pulse position modulation offers the best performance, followed by subcarrier intensity modulation under weak turbulence environments
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Deconvolution of pro- and antiviral genomic responses in Zika virus-infected and bystander macrophages.
Genome-wide investigations of host-pathogen interactions are often limited by analyses of mixed populations of infected and uninfected cells, which lower sensitivity and accuracy. To overcome these obstacles and identify key mechanisms by which Zika virus (ZIKV) manipulates host responses, we developed a system that enables simultaneous characterization of genome-wide transcriptional and epigenetic changes in ZIKV-infected and neighboring uninfected primary human macrophages. We demonstrate that transcriptional responses in ZIKV-infected macrophages differed radically from those in uninfected neighbors and that studying the cell population as a whole produces misleading results. Notably, the uninfected population of macrophages exhibits the most rapid and extensive changes in gene expression, related to type I IFN signaling. In contrast, infected macrophages exhibit a delayed and attenuated transcriptional response distinguished by preferential expression of IFNB1 at late time points. Biochemical and genomic studies of infected macrophages indicate that ZIKV infection causes both a targeted defect in the type I IFN response due to degradation of STAT2 and reduces RNA polymerase II protein levels and DNA occupancy, particularly at genes required for macrophage identity. Simultaneous evaluation of transcriptomic and epigenetic features of infected and uninfected macrophages thereby reveals the coincident evolution of dominant proviral or antiviral mechanisms, respectively, that determine the outcome of ZIKV exposure
Performance of Garden Pea Genotypes in Eastern Hills of Nepal
Garden pea (Pisum sativum L) is an important winter legume used as fresh vegetables and other drier food products. Despite of its importance as cash crop in many parts of Nepal, much study on various aspects for enhancing production and productivity has yet to be done. Therefore, to evaluate the production performance different genotypes of garden pea in eastern hills agro-ecological conditions present experiments were carried out consecutively for two years (2015 and 2016) at Agricultural Research Station, Pakhribas. The experiment comprised of 11 different genotypes of garden pea including a check variety Arkel. The production performance was evaluated in a completely randomized block design with three replications. The seeds were sown at 50 × 10 cm spacing during first week of October for two years. The result showed that DGP-05 genotype had earliest 104 days after sowing. The DGP-08 genotype showed 13 which were the maximum numbers of pods per plant (13), while DGP-01 showed 8 numbers of seeds as the maximum per pod. The DGP-03 genotype had the longest pod of 9.78 cm among others. The highest fresh pod yield of 18.14 t/ha was achieved from genotype DGP-09 followed by Arkel with (16.32 t/ha).Journal of Nepal Agricultural Research Council Vol.3 2017: 15-1
Sunyaev-Zel'dovich Effect by Multiple Sctattering : Numerical Solution of the Transfer Equations
The radiative transfer equations for multiple inverse Compton scattering of
the Cosmic Microwave Background Radiation (CMBR) by the hot intra-cluster
electrons are solved numerically. The spherical isothermal and inhomogeneous
model has been considered for the electron distribution. The anisotropy
of the CMBR caused by scattering, known as thermal Sunyaev-Zel'dovich effect,
along the radial axis of the medium is compared with the analytical solution of
Kompaneets equation. The X-ray data of several clusters of galaxies at low
redshifts provide an estimation of the central electron density to be of
the order . It is found that for this value of the effect of
multiple scattering is negligible. The numerically calculated anisotropy along
the radial axis matches well with the analytical solution that describes single
scattering. The result incorporating multiple scattering is fitted with the
recent observation of Sunyaev-Zel'dovich effect in the cluster Abell 2163. It
is shown that if is greater by an order of magnitude, which could be
possible for cluster of galaxies at comparatively higher redshift, multiple
scattering would play a significant role at the Wien region of the anisotropy
spectrum. A fitting formula for the correction to the Sunyaev-Zel'dovich effect
due to multiple scattering is provided.Comment: 9 pages, Latex, ws-ijmpa style (cls file included), 3 postscript
figures, Accepted for publication by International Journal of Modern Physics
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