4,443 research outputs found
The Nutritional Status of Elites in India, Kenya, and Zambia: An appropriate guide for developing reference standards for undernutrition?
Assessments of undernutrition are typically based on comparisons between anthropometric indicators of children and a reference standard from the US. Due to a number of problems associated with this reference standard, WHO is currently engaged in generating a new international reference standard for child growth based on wellÂtoÂdo populations in a sample of poor and rich countries. The focus on socioeconomic elites is to ensure that the measured growth reflects their genetic potential (and not according their constrained environment). Based on an analysis of the Demographic and Health Surveys from Kenya, India, and Zambia, we identify a number of problems associated with using socioeconomic elites as representative of the genetic potential of a population. First, there are several, nonÂoverlapping ways to identify elites. Second, the anthropometric status of elites appears to depend to a considerable degree on the nutrition and health status of nonÂelites. Third, there is a danger that the elites are not a random sample of the growth potential of the population. And lastly, it appears that the nutritional status of elites differs substantially between the three countries so that it is unclear how one can combine them to generate one international reference standard
Modelling Fast-Alfv\'en Mode Conversion Using SPARC
We successfully utilise the SPARC code to model fast-Alfv\'en mode conversion
in the region via 3-D MHD numerical simulations of helioseismic
waves within constant inclined magnetic field configurations. This was achieved
only after empirically modifying the background density and gravitational
stratifications in the upper layers of our computational box, as opposed to
imposing a traditional Lorentz Force limiter, to ensure a manageable timestep.
We found that the latter approach inhibits the fast-Alfv\'en mode conversion
process by severely damping the magnetic flux above the surface.Comment: Proceedings of GONG 2012 / LWS/SDO-5 / SOHO 27 (Eclipse on the Coral
Sea: Cycle 24 Ascending) Conference, November 12 -16, 2012, Palm Cove,
Australi
Sensitivity of helioseismic travel-times to the imposition of a Lorentz force limiter in computational helioseismology
The rapid exponential increase in the Alfv\'en wave speed with height above
the solar surface presents a serious challenge to physical modelling of the
effects of magnetic fields on solar oscillations, as it introduces a
significant CFL time-step constraint for explicit numerical codes. A common
approach adopted in computational helioseismology, where long simulations in
excess of 10 hours (hundreds of wave periods) are often required, is to cap the
Alfv\'en wave speed by artificially modifying the momentum equation when the
ratio between Lorentz and hydrodynamic forces becomes too large. However,
recent studies have demonstrated that the Alfv\'en wave speed plays a critical
role in the MHD mode conversion process, particularly in determining the
reflection height of the upward propagating helioseismic fast wave. Using
numerical simulations of helioseismic wave propagation in constant inclined
(relative to the vertical) magnetic fields we demonstrate that the imposition
of such artificial limiters significantly affects time-distance travel times
unless the Alfv\'en wave-speed cap is chosen comfortably in excess of the
horizontal phase speeds under investigation.Comment: 8 pages, 5 figures, accepted by ApJ
Molecular epidemiology of high-risk types of Human Papillomaviruses (16, 18) in pap-smear, the North East of Iran
Background: Cervical Cancer is one of the most important and commonly diagnosed types of cancer in females. There are different causes of cervical cancer, amongst which recurrent and persistent infection with HPV types 16 and 18 are the most renowned ones. These genotypes are the main factors in 99% of cases in developed countries and 70% in developing ones. Due to the importance of these viruses in cervical cancer, molecular detection of HPV and its high risk genotypes in Gorgan was designed. Methods: Pap smears and swabs specimens were taken from 308 women. Papanicola staining method and cytology were used. Nucleic acid was extracted by proteinase K phenol-chloroform standard method and then assessed by using beta-globin primer. Polymerase Chain Reaction (PCR) was then performed for papilomaviruses on all patients and positive cases from both types, including HPV 16 and 18 genotypes, were detected. Results: Three hundred and eight women (15-75 years old) with mean age of 37.54±10.6 were recruited. Seventy six cases (20.1%) of whom were infected with HPV and 48.6% with HPV16 or 18 positive. Normal cytology was seen in 226 cases and 41 patients (18.1%) were HPV positive. Amongst those 152 cases with inflammation or abnormal cytology, 35 cases (23%) were HPV positive. No significant relation was reported between different variables and HPV infections. Conclusions: Due to high rate of HPV infection, as well as its high risk genotypes in different studies, more careful screening of women by Pap smear is recommended
Optimization of a solar air heater with phase change materials: Experimental and ‎numerical study
In this paper, a solar air heater (SAH) with phase change material (PCM)-based energy storage is ‎investigated. Paraffin was placed underneath the absorber plate as the PCM. A transient two-‎dimensional laminar model was used in the Ansys Fluent 17 software to study the effects of different ‎parameters on the performance of the SAH, such as the air mass flow rate, the amount of paraffin, and ‎the thermal conductivity of the paraffin. The performance of the SAH was optimized by considering ‎two objectives simultaneously: thermal energy efficiency and maximum nocturnal temperature ‎difference between the inlet and the outlet of the SAH. To validate the numerical model, a SAH with ‎a 2-cm paraffin layer and the same dimensions as the numerical model was built and tested. The ‎results of the simulation showed good agreement with the experimental results.
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