6,047 research outputs found
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
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.
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 welltodo 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, nonoverlapping ways to identify elites. Second, the anthropometric status of elites appears to depend to a considerable degree on the nutrition and health status of nonelites. 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
Directional Time-Distance Probing of Model Sunspot Atmospheres
A crucial feature not widely accounted for in local helioseismology is that
surface magnetic regions actually open a window from the interior into the
solar atmosphere, and that the seismic waves leak through this window, reflect
high in the atmosphere, and then re-enter the interior to rejoin the seismic
wave field normally confined there. In a series of recent numerical studies
using translation invariant atmospheres, we utilised a "directional
time-distance helioseismology" measurement scheme to study the implications of
the returning fast and Alfv\'en waves higher up in the solar atmosphere on the
seismology at the photosphere (Cally & Moradi 2013; Moradi & Cally 2014). In
this study, we extend our directional time-distance analysis to more realistic
sunspot-like atmospheres to better understand the direct effects of the
magnetic field on helioseismic travel-time measurements in sunspots. In line
with our previous findings, we uncover a distinct frequency-dependant
directional behaviour in the travel-time measurements, consistent with the
signatures of MHD mode conversion. We found this to be the case regardless of
the sunspot field strength or depth of its Wilson depression. We also isolated
and analysed the direct contribution from purely thermal perturbations to the
measured travel times, finding that waves propagating in the umbra are much
more sensitive to the underlying thermal effects of the sunspot.Comment: 9 pages, 8 figures, accepted for publication in Monthly Notices of
the Royal Astronomical Society Main Journa
Anti-influenza antibody level after vaccination in north of Iran
Objective:Influenza is a highly transmitted disease and about 10% of the world's population is affected by this disease annually. The aim of this research was to study the variation of serum antibody levels among subjects who had already been vaccinated against influenza. Methods And Materials:This descriptive-analytical study was carried out on 196 subjects who had influenza vaccination (influvac 2005/2006) and on 200 subjects who were matched with the vaccinated subjects by their ages in Gorgan which is located in the northeast of Iran. The subject's sera were prepared seven weeks after the influenza vaccination. Their serum antibody levels were determinated by the heamaglutination inhibition test. Results:The antibody titre in 81 subjects of the vaccinated group and in 175 subjects of the control group was less then 1/40. The mean antibody titre of the vaccinated subjects and the control group was 143.4±10.89 and 18.34±3.2, respectively. The difference was statistically significant (P value=0.000). Conclusion:The findings showed that the mean titre of the antibodies in the vaccinated and control groups was statistically different. This means that the influenza vaccine has good efficacy in our population
Convergence analysis of the Chebyshev-Legendre spectral method for a class of Fredholm fractional integro-differential equations
In this paper, we propose and analyze a spectral Chebyshev-Legendre
approximation for fractional order integro-differential equations of Fredholm
type. The fractional derivative is described in the Caputo sense. Our proposed
method is illustrated by considering some examples whose exact solutions are
available. We prove that the error of the approximate solution decay
exponentially in L^2-norm.Comment: 20 pages, 5 figures, 1 tabl
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