947 research outputs found
Enhanced Photocatalytic Water Splitting with Two-Dimensional van der Waals Heterostructures of BAs/WSeTe
Transfer of skills from simulation lab to surgical services:Impact of a decade long laparoscopic urology surgical course
Fine-Grid Calculations for Stellar Electron and Positron Capture Rates on Fe-Isotopes
The acquisition of precise and reliable nuclear data is a prerequisite to
success for stellar evolution and nucleosynthesis studies. Core-collapse
simulators find it challenging to generate an explosion from the collapse of
the core of massive stars. It is believed that a better understanding of the
microphysics of core-collapse can lead to successful results. The weak
interaction processes are able to trigger the collapse and control the
lepton-to-baryon ratio () of the core material. It is suggested that the
temporal variation of within the core of a massive star has a pivotal
role to play in the stellar evolution and a fine-tuning of this parameter at
various stages of presupernova evolution is the key to generate an explosion.
During the presupernova evolution of massive stars, isotopes of iron, mainly
Fe, are considered to be key players in controlling ratio
via electron capture on these nuclide. Recently an improved microscopic
calculation of weak interaction mediated rates for iron isotopes was introduced
using the proton-neutron quasiparticle random phase approximation (pn-QRPA)
theory. The pn-QRPA theory allows a microscopic \textit{state-by-state}
calculation of stellar capture rates which greatly increases the reliability of
calculated rates. The results were suggestive of some fine-tuning of the
ratio during various phases of stellar evolution. Here we present for
the first time the fine-grid calculation of the electron and positron capture
rates on Fe. Core-collapse simulators may find this calculation
suitable for interpolation purposes and for necessary incorporation in the
stellar evolution codes.Comment: 21 pages, 6 ps figures and 2 table
Gamow-Teller transitions from 24Mg and its impact on the electron capture rates in the O + Ne + Mg cores of stars
Electron captures on nuclei play an important role in the collapse of stellar
core in the stages leading to a type-II supernova. Recent observations of
subluminous Type II-P supernovae (e.g. 2005cs, 2003gd, 1999br) were able to
rekindle the interest in 8 - 10 which develop O+Ne+Mg cores. We used the
proton-neutron quasiparticle random phase approximation (pn-QRPA) theory to
calculate the B(GT) strength for 24Mg \rightarrow 24Na and its associated
electron capture rates for incorporation in simulation calculations. The
calculated rates, in this letter, have differences with the earlier reported
shell model and Fuller, Fowler, Newman (hereafter F2N) rates. We compared
Gamow-Teller strength distribution functions and found fairly good agreement
with experiment and shell model. However, the GT centroid and the total GT
strength, which are useful in the calculation of electron capture rates in the
core of massive pre-supernova stars, lead to the enhancement of our rate up to
a factor of four compared to the shell model rates at high temperatures and
densities.Comment: 13 pages, 3 figure
Gamow-Teller transitions and deformation in the proton-neutron random phase approximation
We investigate reliability of Gamow-Teller transition strengths computed in
the proton-neutron random phase approximation, comparing with exact results
from diagonalization in full shell-model spaces. By allowing the
Hartree-Fock state to be deformed, we obtain good results for a wide variety of
nuclides, even though we do not project onto good angular momentum. We suggest
that deformation is as important or more so than pairing for Gamow-Teller
transitions.Comment: 8 pages, 5 figures; added references, clarified discussion with
regards to stabilit
Provider perspectives on sexual health services used by Bangladeshi women with mHealth digital approach : a qualitative study
Cases of sexually transmitted infections (STIs) are underreported in Bangladesh. Women in general suffer from poor sexual health outcomes due to a lack of access to sexual health services. mHealth, a digital approach to STI services, is an easier and cheaper way to disseminate health information in Bangladesh. However, women have less autonomy in accessing STI services and it is important to learn if, how and/or why women use mHealth. A qualitative study was conducted with 26 medical doctors to explore their perceptions of the mHealth STI services used by Bangladeshi women. Themes were grouped under four categories: (1) provider perceptions of mHealth for sexual healthcare; (2) the health literacy of women clients; (3) cost and maintaining timeliness in providing mHealth services; (4) mHealth service accessibility. Data suggest that mHealth can play a significant role in improving the awareness and utilization of STI services in Bangladeshi women. Successful opportunities for STI service expansion using mHealth were identified, depending on the quality and type of service delivery options, awareness of challenges related to health literacy framework, cost, accessibility to information and availability of culturally competent health experts to disseminate health information. We identify the need to increase access and use of mHealth services for sexual health, as it provides an innovative platform to bridge the health communication gaps in sexual health for Bangladeshi women
Gamma ray heating rates due to chromium isotopes in stellar core during late stages of high mass stars (>10M ⊙
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