1,417 research outputs found
Hormonal contraceptive methods and risk of HIV acquisition in women : a systematic review of epidemiological evidence
Peer reviewedPublisher PD
Isotopic Production Cross Sections in Proton-Nucleus Collisions at 200 MeV
Intermediate mass fragments (IMF) from the interaction of Al,
Co and Au with 200 MeV protons were measured in an angular range
from 20 degree to 120 degree in the laboratory system. The fragments, ranging
from isotopes of helium up to isotopes of carbon, were isotopically resolved.
Double differential cross sections, energy differential cross sections and
total cross sections were extracted.Comment: accepted by Phys. Rev.
The Lingering Environmental Impact of Repressive Governance: The Environmental Legacy of the Apartheid Era for the New South Africa
This article aims to explore the historical link between contemporary environmental problems and the environmental, economic and political policies of the apartheid government. The analysis draws on an examination of the detrimental environmental impacts of the apartheid era and how international isolation impacted on governmental environmental management in the country, before turning attention to the way in which the ANC government has managed the South African natural and human environments in the period after 1994. The article shows that despite many important new developments since 1994, that there are high levels of continuity between the environmental management practices of the old and the new regimes. This state of affairs negatively impacts on the ability of the ANC government to provide every South African citizen with the clean and safe environment guaranteed to all within the 1996 Bill of Rights.This article also appeared unchanged as a chapter in the following edited collection: Jan Oosthoek and Barry K. Gills (eds), _The Globalization of Environmental Crisis_ (Abingdon: Routledge, 2008), pp. 109-120
Second T = 3/2 state in B and the isobaric multiplet mass equation
Recent high-precision mass measurements and shell model calculations~[Phys.
Rev. Lett. {\bf 108}, 212501 (2012)] have challenged a longstanding explanation
for the requirement of a cubic isobaric multiplet mass equation for the lowest
isospin quartet. The conclusions relied upon the choice of the
excitation energy for the second state in B, which had two
conflicting measurements prior to this work. We remeasured the energy of the
state using the reaction and significantly disagree
with the most recent measurement. Our result supports the contention that
continuum coupling in the most proton-rich member of the quartet is not the
predominant reason for the large cubic term required for nuclei
An updated systematic review of epidemiological evidence on hormonal contraceptive methods and HIV acquisition in women
We are grateful to Sharon Achilles for her thoughtful input related to describing potential biological mechanisms, and to all study investigators who provided additional information about their analyses. WHO provided support for the writing of this systmatic review and for the writing group to attend a working meeting in Geneva, Switzerland in October 2015. D.J.W. was partially funded by NIH DP2-HD-08-4070. The review was conducted independently of the WHO guidance development process; and conclusions represent the independent opinions of the authors. The findings and conclusions in this article do not necessarily reflect the positions and policies of the donor. Role of authors: The World Health Organization (J.N.K. and P.S.S.) initiated the idea to conduct this systematic review update. C.B.P. led the conduct of the systematic review, including conducting the systematic literature search and drafting the manuscript. C.B.P., K.M.C., and P.C.H. screened titles, abstracts, and full-text manuscripts to determine study inclusion. S.J.P. conducted the statistical meta-analysis. All coauthors (C.B.P., K.M.C., P.C.H., S.J.P., T.C., J.N.K., D.J.W., and P.S.S.) participated in framing the study question, developing the quality criteria, abstracting study information and assessing study quality, interpreting the data, and contributing to the writing and editing of the manuscript. Disclaimer: The findings and conclusions in this report are those of the authors and do not necessarily represent the official positions of the Guttmacher Institute, the Centers for Disease Control and Prevention, the World Health Organization, the National Institutes of Health, or other institutions with which the authors are affiliated.Peer reviewedPublisher PD
Doping in sport: Attitudes, beliefs and knowledge of competitive high school athletes in Gauteng Province
Objective. To determine the attitudes, beliefs and knowledge of talented young athletes residing in Gauteng regarding prohibited performance-enhancing drugs (PEDs) and anti-doping rules and regulations.Methods. This was a survey study using a quantitative research approach. South African TuksSport academy athletes at the High Performance Centre, University of Pretoria, and competitive high-school athletes at four private high schools in Gauteng completed the survey. A selfdetermined, structured questionnaire was used to establish the attitudes, beliefs and knowledge of the athletes.Results. A total of 346 (208 males, 138 females) athletes, mean (standard deviation) age 16.9 (1.4) years participated in the survey. According to this survey, 3.9% of the athletes in this survey admitted to using a prohibited PED and more than 14.0% of the athletes said they would consider using a prohibited PED if they knew they would not get caught. Ambition (46.0%) and emotional pressure (22.5%) were the primary reasons why the athletes would consider using prohibited PEDs. Even though coaches appeared to be one of the main sources of information (on PEDs and anti-doping rules), only 42.1% of the athletes felt that they were well informed.Conclusion. Controlling doping by means of testing is important. However, it may be necessary to put more emphasis on changing attitudes towards doping and implementing additional educational programmes
Study of proton-unbound states in relevant for the reaction in novae
Background: The nucleosynthesis of several proton-rich nuclei is determined
by radiative proton-capture reactions on unstable nuclei in nova explosions.
One such reaction is , which links the
NeNa and MgAl cycles in oxygen-neon (ONe) novae.
Purpose: To extract resonance
strengths from a study of proton-unbound states in , produced
via the Mg(He,) reaction.
Methods: A beam of ions at 50.7 MeV was used to produce
the states of interest in Al. Proton-triton angular correlations were
measured with a QDD magnetic spectrometer and a silicon detector array,
located at iThemba LABS, South Africa.
Results: We measured the excitation energies of the four lowest
proton-unbound states in Al and place lower-limits on
values for these four states. Together with USD-C shell-model calculations of
partial gamma widths, the experimental data are also used to determine
resonance strengths for the three lowest
resonances.
Conclusions: The energy of the dominant first
resonance is determined to be keV, with a resonance
strength meV
Linear amplifiers with phase-sensitive noise
We present a model for a linear amplifier which adds phase-dependent noise to the input signal. This is achieved by preparing the internal modes of the amplifier in a squeezed vacuum. Such a scheme could be used to amplify a squeezed-signal quadrature with reduced added noise compared with conventional schemes. The model discussed could be realized as nondegenerate parametric amplification
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