748 research outputs found

    Interplay between Phonon Confinement and Fano Effect on Raman line shape for semiconductor nanostructures: Analytical study

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    Theoretical Raman line shape functions have been studied to take care of quantum confinement effect and Fano effect individually and jointly. The characteristics of various Raman line shapes have been studied in terms of the broadening and asymmetry of Raman line shapes. It is shown that the asymmetry in the Raman line-shape function caused by these two effects individually does not add linearly to give asymmetry of line-shape generated by considering the combined effect. This indicates existence of interplay between the two effects. The origin of interplay lies in the fact that Fano effect itself depends on quantum confinement effect and in turn provides an asymmetry. This can not be explained by considering the two effects contribution independent of each other.Comment: 10 Page

    Intrinsic Half-metallicity in Edge Fluorinated Armchair Boron Nitride Nanoribbons

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    We predict intrinsic half-metallicity in armchair boron nitride nanoribbons (ABNNRs) via edge fluorination. The stability, electronic and magnetic properties of bare and edge fluorinated ABNNRs have been systematically analyzed by means of first-principles calculations within the local spin-density approximation (LSDA). The ribbons whose only edge-B atoms passivated with F atoms (i.e., edge-N atoms are un-passivated), regardless of width, are found half-metallic with a half-metal gap of 0.3 eV. A 100 \% spin polarized charge transport across the Fermi level is expected for such ribbons as the spin polarized states are \sim0.4 eV more stable than the spin un-polarized states and only single-spin conducting channels are present across the Fermi level owing to the gigantic spin splitting. The existence of half-metallicity is attributed to the localization of electronic charge at bare edge-N atoms as revealed from the analysis of Bloch states and projected density of states (PDOS).The sufficiently large half-metal gap (0.3 eV) with huge difference in the energies (\sim 0.4 eV) of spin polarized and spin compensated states projects these half-metallic ABNNRs as potential candidate for spintronics applications.Comment: Error in Typing in older versio

    Shadow Detection using DWT with Multi-Wavelet Selection & user Configurable Variance Parameters

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    Moving cast shadows are a noteworthy worry in today's execution from expansive scope of numerous vision-based observation applications in light of the fact that they exceedingly troublesome the item characterization assignment. A few shadow identification strategies have been accounted for in the writing amid the most recent years. They are for the most part partitioned into two spaces. One more often than not works with static pictures, though the second one uses picture arrangements, to be specific video content. Regardless of the way that both cases can be similarly dissected, there is a distinction in the application field. The main case, shadow identification strategies can be misused to get extra geometric and semantic signs about shape and position of its throwing article ('shape from shadows') and the restriction of the light source. While in the second one, the primary reason for existing is normally change discovery, scene coordinating or reconnaissance (for the most part in a foundation subtraction connection). In our examination we have fundamentally focusssed on the identification of shadow from the facilitating so as to move article through a video observation test multi-wavelet choice and client configurable difference parameters. In our test client can pick the diverse wavelets and change parameters. Edge model based super determination technique is utilized to improve results. Additionally the impact of advanced watermarking is concentrated on for the super-determined VOP(Video articles planes). Various experiments have been proposed and figured out a best system for video reconnaissance application. Our proposed super determination (SR) system gives preferred results over bilinear and bi-cubic routines

    Yoga is an effective technique of stress reduction within the medical population: a biochemical study in MBBS students of BRD Medical College, Gorakhpur, Uttar Pradesh, India

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    Background: Medicine is a profession with high-stress prevalence. There are many stress markers but cortisol is one of the commonly used stress marker. Stress begins in the first year of medical carrier and increases with subsequent years of medical education. There is a decrease in overall academic performance and many health-related adverse effects due to stress. In this study, yoga was performed in the first year MBBS students of BRD Medical College, Gorakhpur and the impact of yoga in stress reduction was studied using serum cortisol as stress a marker.Methods: Study groups, yoga and control contained 26 and 27 subjects including male and female MBBS students. Yoga group practiced selected yogic asana, pranayama, and yoga nidra for 3 months. The control group as a stress marker had been kept in touch and allowed to go on their usual activity as before. Morning (8.00 AM to 9.00 AM) serum cortisol level was used as a stress marker in both group, pre and post-study.Results: There was a significant reduction in morning serum cortisol level (stress level) in yoga group (p-value = 0.0271) but there was no significant change in morning serum cortisol level of the control group (p-value = 0.8573).Conclusions: Yoga is an effective stress reduction technique for medical students. Yoga classes should be introduced in the first year of the medical carrier under the supervision of expert physiologists. This may lead to the implantation of a healthy lifestyle in our future healthcare providers. Yogic practice by health care providers may have long term positive impacts on our healthcare system

    FACTS placement for reactive power planning with weak node constraints using an improved symbiotic search algorithm

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    In this paper, an economically feasible and reliable operation of the IEEE 57 bus system for Optimal Power Flow (OPF) is proposed. The Improved Symbiotic Organisms Search (ISOS) algorithm is proposed for effective reactive power planning as an OPF issue. Further, the optimal position of Flexible AC Transmission Systems (FACTS) is taken into consideration, by including the existing system controlling variables like reactive power generators output, transformer tapping and capacitors connected at shunt. The objective of the work is two-fold; i.e., to reduce the energy loss and to enhance the voltage profile within the prescribed limit by ensuring the economic operation and investment cost of FACTS in the system. In this work, two FACTS devices like Static Var Compensator (SVC) and Thyristor-Controlled Series Controller (TCSC) have been taken into consideration. Voltage sensitivity indicator and reactive power flow are two tools that are utilised in order to locate weak nodes for the implementation of FACTS. Finally, the performance of the ISOS algorithm is compared with that of three other state- of-the -art optimization techniques, such as, Symbiotic Organisms Search (SOS), Differential Evolution (DE) and Teaching Learning Based Optimization (TLBO). A Non-parametric statistical analysis is also performed to investigate the dominance of the ISOS algorithm over others

    Design and analysis of seven-level hybrid modified H-bridge multilevel inverter

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    This paper introduces a novel boosting multilevel inverter that utilizes switched capacitors. Current multilevel inverters (MLIs) face several issues, such as complex structures, intricate switching controls, and challenges in generating gate pulses, numerous components, and high voltage stress on semiconductors. The increase in the number of levels adds to the complexity and cost of the circuit and can reduce reliability in some cases. The proposed topology creates a 7-level voltage waveform using 9 switches, 1 diode, and 2 capacitors, and it triples the voltage gain. The capacitors maintain self balanced operation without the need for additional circuits. A simple logic gate-based pulse-width modulation (PWM) technique is presented to ensure power balancing of the capacitors. The proposed 7-level switched capacitor boosting multilevel inverter features a reduced switch count, lower voltage stress, and built-in fault tolerance. The paper includes a comprehensive comparison of various related topologies. The proposed topology is simulated in PSIM, with simulation results presented for different parameters

    Study of difference in cognitive functions after a single manic episode versus recurrent episodes in euthymic bipolar 1 patients

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    Background: Neurocognitive deficits have been substantially documented in patients with bipolar disorder in the euthymic state. The assessment of cognitive change from first episode mania is crucial in understanding whether cognitive deficits are progressive or already present from the first diagnostic episode of bipolar I disorder. The objective of the study is to assess and compare the cognitive function in bipolar I patients with one manic episode and recurrent episodes currently in remission.Methods: A cross sectional observational study consisting of 3 groups was carried on eighty cases each of bipolar 1 disorder patients in euthymic phase with one manic, more than 3 manic episodes and controls. These were subjected to the neuropsychological assessment and then compared.Results: The patients with recurrent episodes group shows poor performance upon digit span test, visuospatial memory test, verbal learning and memory test, color stroop test and trail making test than patients with single manic episode and healthy controls upon these cognitive tests.Conclusions: The present finding suggest that there is impairment in various cognitive domains like executive function, attention, memory even in bipolar patients after single manic episode
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