Stochastic Model in the Kardar-Parisi-Zhang Universality With Minimal Finite Size Effects

We introduce a solid on solid lattice model for growth with conditional evaporation. A measure of finite size effects is obtained by observing the time invariance of distribution of local height fluctuations. The model parameters are chosen so that the change in the distribution in time is minimum. On a one dimensional substrate the results obtained from the model for the roughness exponent $\alpha$ from three different methods are same as predicted for the Kardar-Parisi-Zhang (KPZ) equation. One of the unique feature of the model is that the $\alpha$ as obtained from the structure factor $S(k,t)$ for the one dimensional substrate growth exactly matches with the predicted value of 0.5 within statistical errors. The model can be defined in any dimensions. We have obtained results for this model on a 2 and 3 dimensional substrates.Comment: 8 pages, 7 figures, accepted in Phys. Rev.

Absorption and luminescence of hydrogen and oxygen passivated silicon quantum dots

Silicon (Si) quantum dots (QDs) passivated with oxygen and hydrogen of size 1 nm in diameter are prepared by wet chemical route and electrochemical route respectively. The optical measurements reveal the strong absorption feature around 4.7 eV and weak absorption at 3.4 eV for oxygen passivated Si QDs. Hydrogen passivated Si QDs of the same size show absorption at 4.9 eV. Both the oxygen and hydrogen passivated Si QDs show broad luminescence around 3.9 and 3.8 eV. Films of these QDs, when coated on crystalline silicon solar cells, show an increase in the efficiency of the solar cell by 12 %. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/2788

Analysis of caesarean sections according to Robson’s criteria at a tertiary care teaching hospital in central India

Background: The rate of caesarean section (CS) has been skyrocketed globally over the past three decades which makes it utmost essential to be reanalyzed. Hence, the Robson’s classification of international standards has become a need of an hour. This study aimed to analyze the trend of caesarean sections at a tertiary care teaching hospital, by using Robson’s criteria.Methods: This cross-sectional observational study was conducted at Government Medical College in Akola. The data was collected for the women delivered by CS during November 2017 to April 2019 and proportions in various groups as per Robson’s criteria were calculated.Results: The overall CS rate for the study period at our hospital was 63.89%. Robson Group 1 (24.5%) had the greatest representation in the study population followed by Group 5 (21.27%) and 3 (14.18%). While Groups 6 (10.13%) and 9 (0.63%) had the least representation. Group 5 was found to be the highest absolute contributor (20.5%) to overall CS rates followed by Group 1 (16.08%). Group 9 had a least possible share in the study population, but it had 100% CS rate.Conclusions: Robson’s classification must be implemented in all delivery units to avoid unnecessary caesarean sections. Every effort should be made to provide caesarean sections to women in need, rather than striving to achieve a specific rate and Robson’s criteria is a step forward in the same direction

Large Eddy Simulation Study of Atmospheric Boundary Layer Flow over an Abrupt Rough-to-Smooth Surface Roughness Transition

The atmospheric boundary layer flow downstream of an abrupt rough-to-smooth surface roughness transition is studied using large eddy simulations (LES) for a range of surface roughness ratios. Standard wall models assume horizontal homogeneity and are inapplicable for heterogeneous surfaces. Two heterogeneous-surface wall models are evaluated, one based on a local application of similarity theory using a twice-filtered velocity field (BZ model) and another based on a local friction-velocity obtained by blending the upstream and downstream profiles (APA model). The wall shear stress and the turbulence intensity (TI) are sensitive to the wall model while the mean streamwise velocity and the total shear stress (TSS) are less sensitive. The APA model is more accurate than the BZ model on comparison to previous experiments. The wall shear stress obtained using the APA wall model is sensitive to the ratio of the equilibrium and the internal boundary layer (IBL) heights, while other statistics are not. The IBL height is insensitive to the turbulent quantity (TSS or TI) on which it is based. Several analytical relations for the IBL height are evaluated using the LES data. Two models are found to be accurate for different roughness ratios while one model is reasonable over the full range investigated. A phenomenological model is developed for the TI downstream of the roughness jump using a weighted average of the upstream and far-downstream profiles. The model yields reasonable predictions for all roughness ratios investigated

Nanometer-scale studies of Al–Ga interdiffusion and As precipitate coarsening in nonstoichiometric AlAs/GaAs superlattices

We have investigated the effects of post-growth annealing on Al–Ga interdiffusion and As precipitate coarsening in AlAs/GaAs superlattices grown by molecular-beam epitaxy at low temperatures. High-resolution x-ray diffraction spectra show a significant decrease in the number and intensity of satellite peaks for the ex situ annealed compared with the as-grown superlattices, a feature which is often attributed to a reduction in interface abruptness. However, our cross-sectional scanning tunneling microscopy images show significant variation in the apparent superlattice period of the ex situ annealed compared with the as-grown superlattices. For the as-grown superlattices, preferential As precipitation on the GaAs side of AlAs/GaAs interfaces is evident. In the ex situ annealed superlattices, a preference for As precipitates at the GaAs on AlAs interface is apparent, although the As precipitates are no longer restricted to the interface region. Thus, the apparent change in superlattice period is likely due to variations in As precipitate density, which may be influenced by AlAs–GaAs alloying at the AlAs/GaAs interfaces. © 1999 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70551/2/APPLAB-75-26-4082-1.pd

Is prenatal screening for Down syndrome needed in young pregnant women?

Background: Down syndrome originally known as Mongoloid’s idiocy is the most common autosomal disorder. Down syndrome (DS) can be detected by prenatal diagnosis which includes the triple marker screening test and chromosomal analysis.Methods: The study population comprised of 100 pregnant females amongst the age group of 20-45 (32.10±4.86) years. Triple Marker Test was done followed by amniocentesis or CVS with karyotyping or FISH.Results: Risk of <1:250 was considered high risk whereas ≥1:250 was considered as low risk. 32/45 (71%) were false-positive for Trisomy 21 detected as high risk by TMT. But there was good sensitivity and specificity for Trisomy 18.Conclusions: It can be concluded that the triple marker test is indeed only a screening test for the DS and that it has to be confirmed with the help of chromosomal analysis. The higher maternal age is an important parameter in DS but nowadays, even ones with a lower maternal age can also have a child with DS. So, in general, now all women are recommended to go for biochemical screening during their pregnancy

Pulsed laser treatment at Fe/C<SUB>6</SUB>H<SUB>6</SUB> interface: a Mossbauer effect study

The pulsed ruby laser induced reactive-quenching process at Fe/C6H6 Ibenzenel has been investigated using conversion electron Mossbauer spectroscopy [CEMS]. It is shown that iron carbide phases can be synthesized when an iron foil immersed in benzene is treated with ruby Laser pulses [&#955;=694 nm, pulse width ~30 ns, energy density =15 J/cm2]. The results indicate the formation of &#949;-carbide and Fe5C2 phases in the as-treated sample and its transformation to Fe3C upon thermal treatment. The result of the CEMS measurements are supported by small angle X-ray diffractometry