392 research outputs found
Non-linear damping of visco-resistive Alfven waves in solar spicules
Interaction of Alfven waves with plasma inhomogeneities generates phase
mixing which can lead to dissipate Alfven waves and to heat the solar plasma.
Here we study the dissipation of Alfven waves by phase mixing due to viscosity
and resistivity variations with height. We also consider nonlinear
magnetohydrodynamic (MHD) equations in our theoretical model. Non-linear terms
of MHD equations include perturbed velocity, magnetic field, and density. To
investigate the damping of Alfven waves in a stratified atmosphere of solar
spicules, we solve the non-linear MHD equations in the x-z plane. Our
simulations show that the damping is enhanced due to viscosity and resistivity
gradients. Moreover, energy variations is influenced due to nonlinear terms in
MHD equations.Comment: Accepted for publication in Astrophysics and Space Science Journal.
arXiv admin note: substantial text overlap with arXiv:1304.776
Design of Adiabatic MTJ-CMOS Hybrid Circuits
Low-power designs are a necessity with the increasing demand of portable
devices which are battery operated. In many of such devices the operational
speed is not as important as battery life. Logic-in-memory structures using
nano-devices and adiabatic designs are two methods to reduce the static and
dynamic power consumption respectively. Magnetic tunnel junction (MTJ) is an
emerging technology which has many advantages when used in logic-in-memory
structures in conjunction with CMOS. In this paper, we introduce a novel
adiabatic hybrid MTJ/CMOS structure which is used to design AND/NAND, XOR/XNOR
and 1-bit full adder circuits. We simulate the designs using HSPICE with 32nm
CMOS technology and compared it with a non-adiabatic hybrid MTJ/CMOS circuits.
The proposed adiabatic MTJ/CMOS full adder design has more than 7 times lower
power consumtion compared to the previous MTJ/CMOS full adder
Solar gravitational energy and luminosity variations
Due to non-homogeneous mass distribution and non-uniform velocity rate inside
the Sun, the solar outer shape is distorted in latitude. In this paper, we
analyze the consequences of a temporal change in this figure on the luminosity.
To do so, we use the Total Solar Irradiance (TSI) as an indicator of
luminosity. Considering that most of the authors have explained the largest
part of the TSI modulation with magnetic network (spots and faculae) but not
the whole, we could set constraints on radius and effective temperature
variations (dR, dT). However computations show that the amplitude of solar
irradiance modulation is very sensitive to photospheric temperature variations.
In order to understand discrepancies between our best fit and recent
observations of Livingston et al. (2005), showing no effective surface
temperature variation during the solar cycle, we investigated small effective
temperature variation in irradiance modeling. We emphasized a phase-shift
(correlated or anticorrelated radius and irradiance variations) in the (dR,
dT)-parameter plane. We further obtained an upper limit on the amplitude of
cyclic solar radius variations, deduced from the gravitational energy
variations. Our estimate is consistent with both observations of the
helioseismic radius through the analysis of f-mode frequencies and observations
of the basal photospheric temperature at Kitt Peak. Finally, we suggest a
mechanism to explain faint changes in the solar shape due to variation of
magnetic pressure which modifies the granules size. This mechanism is supported
by our estimate of the asphericity-luminosity parameter, which implies an
effectiveness of convective heat transfer only in very outer layers of the Sun.Comment: 17 pages, 2 figure, 1 table, published in New Astronom
Developing a Structural Equation Modeling of the Role of Academic Stressors on Resilience, Motivation and Academic Burnout Among Pre-University Female in Isfahan
The purpose of this study was to develop a structural equation model of the role of academic stressors on resiliency, motivation and academic burnout among female participants of entrance exam of University in Isfahan. The population was female participants of entrance exam. Two hundred pre-university females were selected by random multistage method as samples of this study. The questionnaires: The Classroom and School Community (Rovai, 2002), Sarason Test Anxiety (1980), Frost Multidimensional Perfectionism (1990), Ego-Resiliency (Klohnen, 1996), Academic Motivation (Vallerand, 1992), Academic Burnout (Breso, 2007) were used. Confirmatory Factor Analysis (CFA) was used for studying structural equation and AMOS-1 was used for evaluating suggested model. According to proper fitting of final model, this model was verified and accepted. The results of research showed that the academic stressors were effective on academic burnout variables, academic motivation and resiliency variable. Also resiliency, as a mediator variable of academic stressors, led to educational inefficiency. The increase of academic stressors decreased academic motivation, especially internal motivation and resiliency, as a result the educational inefficiency increased. These pressures predicted academic burnout
Systematic review of available guidelines on fertility preservation of young patients with breast cancer
Background: Since the survival rate of breast cancer patients has improved, harmful effects of new treatment modalities on fertility of the young breast cancer patients has become a focus of attention. This study aimed to systematically review and critically appraise all available guidelines for fertility preservation in young breast cancer patients. Materials and Methods: Major citation databases were searched for treatment guidelines. Experts from relevant disciplines appraised the available guidelines. The AGREE II Instrument that includes 23 criteria in seven domains (scope and purpose of the guidelines, stakeholder involvement, rigor of development, clarity, applicability, editorial independence, and overall quality) was used to apprise and score the guidelines. Results: The search strategy retrieved 2,606 citations; 72 were considered for full-text screening and seven guidelines were included in the study. There was variability in the scores assigned to different domains among the guidelines. ASCO (2013), with an overall score of 68.0, had the highest score, and St Gallen, with an overall score of 24.7, had the lowest scores among the guidelines. Conclusions: With the promising survival rate among breast cancer patients, more attention should be given to include specific fertility preservation recommendations for young breast cancer patients
Decolorization of Reactive Black-5 High Concentration by Vermicompost Microflora and Detoxification of By-Products by UV-C/H2O2 Post-Treatment
The presence of synthetic dyes in textile wastewater is a problematic issue for environmentalist. Nowadays, dye removal is practiced via different methods. Among all these methods, biodecolorization is an ideal technique. The present research apples vermicompost microflora to remove reactive black-C, pH = 7, and under anaerobic condition. At 36h, removal efficiencies of 94.79%, 94.06%, and 93.6% are obtained for concentrations of 800, 850, and 950 mg/L, respectively. It has also been observed that when the initial concentration rises to 1400 mg/L, the efficiency drops to 51.57% at 36h. Also, methyl red, methyl orange, eriochrome black-t, and acid blue-113 could be decolorized by the isolated bacterial strain with an efficiency of 94.29%, 92.10%, 90.83%, and 88.95%, respectively. Phytotoxicity Test shows that the parent form of reactive black-5 has not been toxic for the seeds (100% germination for Triticum aestivum and 90% for Maize). When reactive black-5 is treated with isolated bacterial strain under anaerobic condition, none of the seeds remain germinated which might be due to the possible formation of toxic aromatic amines intermediates. Therefore, ultraviolet C + 100 mM H2O2 has been used as the post-treatment process for detoxifying of by-products. After the integrated treatment of synthetic wastewater, containing RB-5, complete germination (100%) of Triticum aestivum and Maize is observed. In the post-treatment process, due to the generation and activation of hydroxyl radicals, the toxic aromatic amines compounds convert to the less toxic compounds.
Keywords:azo dyes; anaerobic removal; integrated treatment; phytotoxicity; hydroxyl radical
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