Role of topological defects in the phase transition of modified XY model : A Monte Carlo study

Monte Carlo simulation has been performed on a classical two dimensional XY- model with a modified form of interaction potential to investigate the role of topological defects on the phase transition exhibited by the model. In simulations in a restricted ensemble without defects, the system appears to remain ordered at all temperatures. Suppression of topological defects on the square plaquettes in the modified XY- model leads to complete elimination of the phase transition observed in this model.Comment: 19 pages, 12 figures, Accepted for publication in Phys. Rev.

Scattering states of a particle, with position-dependent mass, in a PT{\cal{PT}} symmetric heterojunction

The study of a particle with position-dependent effective mass (pdem), within a double heterojunction is extended into the complex domain --- when the region within the heterojunctions is described by a non Hermitian ${\cal{PT}}$ symmetric potential. After obtaining the exact analytical solutions, the reflection and transmission coefficients are calculated, and plotted as a function of the energy. It is observed that at least two of the characteristic features of non Hermitian ${\cal{PT}}$ symmetric systems --- viz., left / right asymmetry and anomalous behaviour at spectral singularity, are preserved even in the presence of pdem. The possibility of charge conservation is also discussed.Comment: 12 pages, including 6 figures; Journal of Physics A : Math. Theor. (2012

Modeling the Field Emission Current Fluctuation in Carbon Nanotube Thin Films

Owing to their distinct properties, carbon nanotubes (CNTs) have emerged as promising candidate for field emission devices. It has been found experimentally that the results related to the field emission performance show variability. The design of an efficient field emitting device requires the analysis of the variabilities with a systematic and multiphysics based modeling approach. In this paper, we develop a model of randomly oriented CNTs in a thin film by coupling the field emission phenomena, the electron-phonon transport and the mechanics of single isolated CNT. A computational scheme is developed by which the states of CNTs are updated in time incremental manner. The device current is calculated by using Fowler-Nordheim equation for field emission to study the performance at the device scale.Comment: 4 pages, 5 figure

Scattering states of a particle, with position-dependent mass, in a double heterojunction

In this work we obtain the exact analytical scattering solutions of a particle (electron or hole) in a semiconductor double heterojunction - potential well / barrier - where the effective mass of the particle varies with position inside the heterojunctions. It is observed that the spatial dependence of mass within the well / barrier introduces a nonlinear component in the plane wave solutions of the continuum states. Additionally, the transmission coefficient is found to increase with increasing energy, finally approaching unity, whereas the reflection coefficient follows the reverse trend and goes to zero.Comment: 7 pages, 6 figure

Biomechanical corneal changes induced by different flap thickness created by femtosecond laser

OBJECTIVE: To evaluate the impact of the creation of corneal flaps at different thicknesses on the biomechanical properties of swine corneas. METHOD: Twelve swine eyes were obtained to form two groups: 100 μm flap thickness and 300 μm flap thickness. Each eye was submitted to the following examinations: raster topography to investigate corneal curvature alterations, ocular response analyzer to investigate corneal hysteresis change, optical coherence tomography to measure central corneal and flap thickness and sonic wave propagation velocity as a measure of stiffness, before and immediately after flap creation. After flap amputation, surface wave velocity measurements were repeated. RESULTS: Measured flap thicknesses were statistically different for thin and thick flap groups, with an average of 108.5 + 6.9 and 307.8 + 11.5 μm respectively. Hysteresis and corneal resistance factor did not change significantly after flap creation in the thin flap group. With thicker flaps, both parameters decreased significantly from 8.0 +1.0 to 5.1 +1.5 mmHg and from 8.2 + 1.6 to 4.1 +2.5 mmHg respectively. Simulated keratometry values increased in the thick flap group (from 39.5 + 1 D to 45.9+1.2 D) after flap creation but not in the thin flap group (from 40.6 + 0.6 D to 41.4+ 1.0 D). Regarding surface wave velocity analysis, the surgical procedures induced statistically lower results in some positions. CONCLUSION: In the experimental conditions established by this model, thicker flaps presented a greater biomechanical impact on the cornea.National Institutes of Health (NIH)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Association of Physical Activity and Screen Time Usage of Adolescents in Rural Areas of Mysore.

Introduction: In these changing times there have been increased usage of screen device due to more accessibility to both device and the internet and a greater number of children are having reduced physical activity. The purpose of the current study was to determine if screen usage among adolescents (11-17yrs) who live in supportive environments is associated with decreased levels of moderate to vigorous physical activity. Methods & materials: A school-based cross-sectional study was conducted in two rural schools of Mysore, Karnataka in February 2023, in 176 students between the age group of 11 – 17yrs. Physical activity and screen time was evaluated using a questionnaire. School sports, Leisure Time Physical Activity (LTPA), and mode of transportation to school was evaluated for their physical activity pattern and the amount of time spent on each type of screen device – TV, Computers, video games, mobile phones, and tablets was measured in hours per day. Results: Prevalence of excessive screen time usage was 36%and physical activity \u3e1hr./day was found to be 57% in study subjects. However, there is no correlation between physical exercise and screen time found in rural adolescents. Conclusion: Prevalence of excessive screen time with 57% of adolescents having physical activity more than 1hr/day. A tighter control of screen usage was also shown by 77% of adolescents, being role models for appropriate screen time, all are factors for an improved lifestyle

Stopping power of hot QCD plasma

The partonic energy loss has been calculated taking both the hard and soft contributions for all the $2 \to 2$ processes, revealing the importance of the individual channels. Cancellation of the intermediate separation scale has been exhibited. Subtleties related to the identical final state partons have properly been taken into account. The estimated collisional loss is compared with its radiative counter part. We show that there exists a critical energy ($E_c$) below which the collisional loss is more than its radiative counterpart. In addition, we present closed form formulas for both the collision probabilities and the stopping power ($dE/dx$)Comment: revised version, section added, 9pages with 5 figure

IGVBrowser–a genomic variation resource from diverse Indian populations

The Indian Genome Variation Consortium (IGVC) project, an initiative of the Council for Scientific and Industrial Research, has been the first large-scale comprehensive study of the Indian population. One of the major aims of the project is to study and catalog the variations in nearly thousand candidate genes related to diseases and drug response for predictive marker discovery, founder identification and also to address questions related to ethnic diversity, migrations, extent and relatedness with other world population. The Phase I of the project aimed at providing a set of reference populations that would represent the entire genetic spectrum of India in terms of language, ethnicity and geography and Phase II in providing variation data on candidate genes and genome wide neutral markers on these reference set of populations. We report here development of the IGVBrowser that provides allele and genotype frequency data generated in the IGVC project. The database harbors 4229 SNPs from more than 900 candidate genes in contrasting Indian populations. Analysis shows that most of the markers are from genic regions. Further, a large fraction of genes are implicated in cardiovascular, metabolic, cancer and immune system-related diseases. Thus, the IGVC data provide a basal level variation data in Indian population to study genetic diseases and pharmacology. Additionally, it also houses data on ∼50 000 (Affy 50 K array) genome wide neutral markers in these reference populations. In IGVBrowser one can analyze and compare genomic variations in Indian population with those reported in HapMap along with annotation information from various primary data sources

IGVBrowser–a genomic variation resource from diverse Indian populations

The Indian Genome Variation Consortium (IGVC) project, an initiative of the Council for Scientific and Industrial Research, has been the first large-scale comprehensive study of the Indian population. One of the major aims of the project is to study and catalog the variations in nearly thousand candidate genes related to diseases and drug response for predictive marker discovery, founder identification and also to address questions related to ethnic diversity, migrations, extent and relatedness with other world population. The Phase I of the project aimed at providing a set of reference populations that would represent the entire genetic spectrum of India in terms of language, ethnicity and geography and Phase II in providing variation data on candidate genes and genome wide neutral markers on these reference set of populations. We report here development of the IGVBrowser that provides allele and genotype frequency data generated in the IGVC project. The database harbors 4229 SNPs from more than 900 candidate genes in contrasting Indian populations. Analysis shows that most of the markers are from genic regions. Further, a large fraction of genes are implicated in cardiovascular, metabolic, cancer and immune system-related diseases. Thus, the IGVC data provide a basal level variation data in Indian population to study genetic diseases and pharmacology. Additionally, it also houses data on ∼50 000 (Affy 50 K array) genome wide neutral markers in these reference populations. In IGVBrowser one can analyze and compare genomic variations in Indian population with those reported in HapMap along with annotation information from various primary data sources