20,703 research outputs found
Temperature-dependent ion mixing and diffusion during sputtering of thin films of CrSi_2 on silicon
Measurements of sputtering yields and composition profiles have been carried out using backscattering spectrometry for samples of CrSi_2 on Si irradiated with 200‐keV Xe ions. When the CrSi_2 layer is thinner than the ion range, the sputtering yield ratio of Si to Cr increases from 3.5 for room‐temperature irradiation to 65 at 290 °C. For a thick sample, the corresponding increase is from 2.4 to 4.0. only. These changes are explained in terms of a rise in the Si surface concentration at 290 °C. The driving force for this process seems to be the establishment of stoichiometric CrSi_2 compound. Transport of Si to the surface is by ion mixing in the thin sample and thermal diffusion through the thick layer
Inequalities in maternity care and newborn outcomes: one-year surveillance of births in vulnerable slum communities in Mumbai
Background: Aggregate urban health statistics mask inequalities. We described maternity care in
vulnerable slum communities in Mumbai, and examined differences in care and outcomes between
more and less deprived groups.
Methods: We collected information through a birth surveillance system covering a population of
over 280 000 in 48 vulnerable slum localities. Resident women identified births in their own
localities and mothers and families were interviewed at 6 weeks after delivery. We analysed data
on 5687 births over one year to September 2006. Socioeconomic status was classified using
quartiles of standardized asset scores.
Results: Women in higher socioeconomic quartile groups were less likely to have married and
conceived in their teens (Odds ratio 0.74, 95% confidence interval 0.69–0.79, and 0.82, 0.78–0.87,
respectively). There was a socioeconomic gradient away from public sector maternity care with
increasing socioeconomic status (0.75, 0.70–0.79 for antenatal care and 0.66, 0.61–0.71 for
institutional delivery). Women in the least poor group were five times less likely to deliver at home
(0.17, 0.10–0.27) as women in the poorest group and about four times less likely to deliver in the
public sector (0.27, 0.21–0.35). Rising socioeconomic status was associated with a lower
prevalence of low birth weight (0.91, 0.85–0.97). Stillbirth rates did not vary, but neonatal mortality
rates fell non-significantly as socioeconomic status increased (0.88, 0.71–1.08).
Conclusion: Analyses of this type have usually been applied across the population spectrum from
richest to poorest, and we were struck by the regularly stepped picture of inequalities within the
urban poor, a group that might inadvertently be considered relatively homogeneous. The poorest
slum residents are more dependent upon public sector health care, but the regular progression
towards the private sector raises questions about its quality and regulation. It also underlines the
need for healthcare provision strategies to take account of both sectors
Supersymmetric geometries of IIA supergravity I
IIA supergravity backgrounds preserving one supersymmetry locally admit four
types of Killing spinors distinguished by the orbits of on the
space of spinors. We solve the Killing spinor equations of IIA supergravity
with and without cosmological constant for Killing spinors representing two of
these orbits, with isotropy groups and .
In both cases, we identify the geometry of spacetime and express the fluxes in
terms of the geometry. We find that the geometric constraints of backgrounds
with a invariant Killing spinor are identical to
those found for heterotic backgrounds preserving one supersymmetry.Comment: 21 page
Thermal analysis applied to estimation of solidification kinetics of Al–Si aluminium alloys
Evaluation of solidification kinetics by thermal analysis is a useful tool for quality control of Al–Si melts before pouring provided it is rapid and highly reproducible. Series of thermal analysis records made with standard cups are presented that show good reproducibility. They are evaluated using a Newton’s like approach to get the instantaneous heat evolution and from it solidification kinetics. An alternative way of calculating the zero line is proposed which is validated by the fact that the latent heat of solidification thus evaluated is within 5% of the value calculated from thermodynamic data. Solidification kinetics was found highly reproducible provided appropriate experimental conditions were achieved: high enough casting temperature for the cup to heat up to the metal temperature well before solidification starts; and equal and homogeneous temperatures of the metal and of the cup at any time in the temperature range used for integration
Measurements of thermodynamic and transport properties of EuC: a low-temperature analogue of EuO
EuC is a ferromagnet with a Curie-temperature of K. It
is semiconducting with the particularity that the resistivity drops by about 5
orders of magnitude on cooling through , which is therefore called a
metal-insulator transition. In this paper we study the magnetization, specific
heat, thermal expansion, and the resistivity around this ferromagnetic
transition on high-quality EuC samples. At we observe well defined
anomalies in the specific heat and thermal expansion data.
The magnetic contributions of and can satisfactorily be
described within a mean-field theory, taking into account the magnetization
data. In zero magnetic field the magnetic contributions of the specific heat
and thermal expansion fulfill a Gr\"uneisen-scaling, which is not preserved in
finite fields. From an estimation of the pressure dependence of via
Ehrenfest's relation, we expect a considerable increase of under applied
pressure due to a strong spin-lattice coupling. Furthermore the influence of
weak off stoichiometries in EuC was studied. It is
found that strongly affects the resistivity, but hardly changes the
transition temperature. In all these aspects, the behavior of EuC strongly
resembles that of EuO.Comment: 7 pages, 6 figure
Chiral properties of hematite ({\alpha}-Fe2O3) inferred from resonant Bragg diffraction using circularly polarized x-rays
Chiral properties of the two phases - collinear motif (below Morin transition
temperature, TM=250 K) and canted motif (above TM) - of magnetically ordered
hematite ({\alpha}-Fe2O3) have been identified in single crystal resonant x-ray
Bragg diffraction, using circular polarized incident x-rays tuned near the iron
K-edge. Magneto-electric multipoles, including an anapole, fully characterize
the high-temperature canted phase, whereas the low-temperature collinear phase
supports both parity-odd and parity-even multipoles that are time-odd. Orbital
angular momentum accompanies the collinear motif, while it is conspicuously
absent with the canted motif. Intensities have been successfully confronted
with analytic expressions derived from an atomic model fully compliant with
chemical and magnetic structures. Values of Fe atomic multipoles previously
derived from independent experimental data, are shown to be completely
trustworthy
Introducing medical parasitology at the University of Makeni, Sierra Leone
The file attached to this record is the author's final peer reviewed version.Capacity building in Sierra Leone (West Africa) is critical to prevent potential future outbreaks similar to
the 2013-16 Ebola outbreak that had devastating effects for the country and its poorly developed
healthcare system. De Montfort University (DMU) in the United Kingdom (UK), in collaboration with
parasitologists from the Spanish Universities of San Pablo CEU and Miguel Hernández de Elche, is
leading a project to build the teaching and research capabilities of medical parasitology at the University
of Makeni (UniMak, Sierra Leone). This project has two objectives: a) to introduce and enhance the
teaching of medical parasitology, both theoretical and practical; and b) to implement and develop
parasitology research related to important emerging human parasites such as Cryptosporidium spp. due
to their public health significance. Two UniMak academics, hired to help initiate and implement the
research part of the project, shared their culturally sensitive public health expertise to broker parasitology
research in communities and perform a comprehensive environmental monitoring study for the detection
of different emerging human parasites. The presence of targeted parasites are being studied
microscopically using different staining techniques, which in turn have allowed UniMak’s academics to
learn these techniques to develop new practicals in parasitology. To train UniMak’s academics and
develop both parts of our project, a DMU researcher visited UniMak for two weeks in April 2019 and
provided a voluntary short training course in basic parasitology, which is currently not taught in any of
their programmes, and was attended by 31 students. These sessions covered basic introduction to
medical parasitology and life-cycle, pathogenesis, detection, treatment and prevention of: a) coccidian
parasites (Cryptosporidium, Cyclospora and Cystoisospora); b) Giardia intestinalis, Entamoeba and
free-living amoebas; c) malaria and d) microsporidia. A theoretical session on common staining
techniques was also provided. To facilitate the teaching and learning of these parasites, the novel
resource DMU e-Parasitology was used, a package developed by the above participating universities
and biomedical scientists from the UK National Health Service (NHS): http://parasitology.dmu.ac.uk/
index.htm. Following the two weeks of training, UniMak’s academics performed different curriculum
modifications to the undergraduate programme ‘Public Health: Medical Laboratory Sciences’, which
includes the introduction of new practicals in parasitology and changes to enhance the content of
medical parasitology that will be subjected to examination. Thus, a new voluntary practical on Kinyoun
stain for the detection of coccidian parasites was introduced in the final year module of ‘Medical
Bacteriology and Parasitology’; eighteen students in pairs processed faecal samples from pigs provided
by the Department of Agriculture and Food Security from a nearby farm. Academics at UniMak used the
Kinyoun staining unit (available at http://parasitology.dmu.ac.uk/learn/lab/Kinyoun/story_html5.html; [1])
to deliver this practical. Although our project is at a preliminary stage, it has been shown to be effective
in promoting the introduction and establishment of medical parasitology at UniMak and could be viewed
as a case-study for other universities in low-income countries to promote the United Nations (UN)
Sustainable Development Goals (SDGs) and improve public health understanding of infectious
diseases
A Resonant soft x-ray powder diffraction study to determine the orbital ordering in A-site ordered SmBaMn2O6
Soft X-ray resonant powder diffraction has been performed at the Mn L2,3
edges of A-site ordered SmBaMn2O6. The energy and polarization dependence of
the (1/2 1/2 0) reflection provide direct evidence for a (x2-z2)/(y2-z2) type
orbital ordering in contrast to the single layer manganite. The temperature
dependence of the reflection indicates an orbital reorientation transition at
210 K, below which the charge and orbital ordered MnO2 sheets show AAAA type of
stacking. The concurring reduction of the ferromagnetic super exchange
correlations leads to further charge localization
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