Thermal effects on electron-phonon interaction in silicon nanostructures

Raman spectra from silicon nanostructures, recorded using excitation laser power density of 1.0 kW/cm^2, is employed here to reveal the dominance of thermal effects at temperatures higher than the room temperature. Room temperature Raman spectrum shows only phonon confinement and Fano effects. Raman spectra recorded at higher temperatures show increase in FWHM and decrease in asymmetry ratio with respect to its room temperature counterpart. Experimental Raman scattering data are analyzed successfully using theoretical Raman line-shape generated by incorporating the temperature dependence of phonon dispersion relation. Experimental and theoretical temperature dependent Raman spectra are in good agreement. Although quantum confinement and Fano effects persists, heating effects start dominating at higher temperatures than room tempaerature.Comment: 9 Pages, 3 Figures and 1 Tabl

MRI Evaluation of Carotid Cavernous Fistula – A Case Report

A carotid cavernous fistula is a rare condition and often difficult to diagnose. We herewith present a case of a female patient who presented with minimal proptosis in the right eye and occipital headache. Magnetic resonance imaging showed classical findings like arterialization of ophthalmic veins and tortuous prominent cavernous sinuses on right side. In such situations, magnetic resonance venography (MRV) plays a major role in the diagnosis and may reveal any cerebral thrombosis. We will be discussing the types of CCF and the MRV findings which help in the diagnosis as well as treatment planning

Malignant meningioma with intra- and extra-cranial extension: A case report

Meningioma is the most common intracranial benign neoplasm. The malignant transformation of this neoplasm is less frequent. Here, we report the case of a 77-year-old male patient who came to our department with a visible mass in the scalp for 1½ years. The mass was gradually increasing in size, soft in nature, not painful, and associated with the left-sided weakness. His multidetector computed tomography showed lesion which is having an intracranial component with the destruction of a vault with extracranial extension. This imaging modality gives a clear-cut picture of the extent of the lesion, nearby structures, and vascularity to give the surgeon proper guidance in two, three, and four dimensions

A rare neglected case of large leptomeningeal cyst: A case report

Leptomeningeal cysts are enlarging skull fractures that occur near post-traumatic encephalomalacia. The term cyst is usually a misnomer as it is not only a cyst but also an extension of encephalomalacia. They commonly occur after severe head trauma during the first 3 years of life (especially infancy) and almost never after 8 years of life. Herewith, we present a case of a 7-year-old female patient who presented to our hospital with left-sided weakness since 2 years and painless swelling over the scalp since 3 years giving past history of head trauma. Plain radiography, computed tomography, and magnetic resonance imaging were performed which showed classical findings of leptomeningeal cyst. We will be discussing about the causes and radiological findings which help in diagnosis as well as treatment planning

Growth, yield and economic potential of rice (Oryza sativa) as influenced by different age of seedlings, cultivars and weed management under system of rice intensification

A field experiment was conducted to study the growth, yield and economic potential of rice as influenced by different age of seedlings, cultivars and weed management under system of rice intensification on sandy-clay-loam soil at Agricultural Research Farm of Institute of Agricultural Sciences, Banaras Hindu University during the two consecutive kharif (rainy) seasons of 2010 and 2011. The experiment was laid out in split-plot design with two ages of seedlings with two cultivars assigned to main plots and seven weed management treatments were allocated as sub- plot treatments has replicated thrice. Transplanting of younger age seedling (10 days) of PHB 71 recorded significantly higher growth attributes, viz. plant height, no. of green leaves/hill and dry matter accumulation with yield attributing characters. Similarly, ten days old seedlings of PHB 71 also produced significantly higher yield (grain and straw) that fetched maximum benefit in respect to gross return, net return and B: C ratio over old aged seedling (15 days) of NDR 359 during 2010 and 2011. Among weed management, cono-weeding 4 times at 10, 20, 30 and 40 days after transplanting (DAT) recorded significantly higher growth attributes, yield attributes and yield, but sequential application of pre and post-emergence herbicides, i e pretilachlor + bispyribac-Na was found economically feasible under SRI due to lesser labour requirement

Spectroscopic investigation of quantum confinement effects in ion implanted silicon-on-sapphire films

Crystalline Silicon-on-Sapphire (SOS) films were implanted with boron (B$^+$) and phosphorous (P$^+$) ions. Different samples, prepared by varying the ion dose in the range $10^{14}$ to 5 x $10^{15}$ and ion energy in the range 150-350 keV, were investigated by the Raman spectroscopy, photoluminescence (PL) spectroscopy and glancing angle x-ray diffraction (GAXRD). The Raman results from dose dependent B$^+$ implanted samples show red-shifted and asymmetrically broadened Raman line-shape for B$^+$ dose greater than $10^{14}$ ions cm$^{-2}$. The asymmetry and red shift in the Raman line-shape is explained in terms of quantum confinement of phonons in silicon nanostructures formed as a result of ion implantation. PL spectra shows size dependent visible luminescence at $\sim$ 1.9 eV at room temperature, which confirms the presence of silicon nanostructures. Raman studies on P$^+$ implanted samples were also done as a function of ion energy. The Raman results show an amorphous top SOS surface for sample implanted with 150 keV P$^+$ ions of dose 5 x $10^{15}$ ions cm$^{-2}$. The nanostructures are formed when the P$^+$ energy is increased to 350 keV by keeping the ion dose fixed. The GAXRD results show consistency with the Raman results.Comment: 9 Pages, 6 Figures and 1 Table, \LaTex format To appear in SILICON(SPRINGER

Effect of temperature anisotropy on various modes and instabilities for a magnetized non-relativistic bi-Maxwellian plasma

Using kinetic theory for homogeneous collisionless magnetized plasmas, we present an extended review of the plasma waves and instabilities and discuss the anisotropic response of generalized relativistic dielectric tensor and Onsager symmetry properties for arbitrary distribution functions. In general, we observe that for such plasmas only those electromagnetic modes whose magnetic field perturbations are perpendicular to the ambient magneticeld, i.e.,B1 \perp B0, are effected by the anisotropy. However, in oblique propagation all modes do show such anisotropic effects. Considering the non-relativistic bi-Maxwellian distribution and studying the relevant components of the general dielectric tensor under appropriate conditions, we derive the dispersion relations for various modes and instabilities. We show that only the electromagnetic R- and L- waves, those derived from them and the O-mode are affected by thermal anisotropies, since they satisfy the required condition B1\perpB0. By contrast, the perpendicularly propagating X-mode and the modes derived from it (the pure transverse X-mode and Bernstein mode) show no such effect. In general, we note that the thermal anisotropy modifies the parallel propagating modes via the parallel acoustic effect, while it modifies the perpendicular propagating modes via the Larmor-radius effect. In oblique propagation for kinetic Alfven waves, the thermal anisotropy affects the kinetic regime more than it affects the inertial regime. The generalized fast mode exhibits two distinct acoustic effects, one in the direction parallel to the ambient magnetic field and the other in the direction perpendicular to it. In the fast-mode instability, the magneto-sonic wave causes suppression of the firehose instability. We discuss all these propagation characteristics and present graphic illustrations

Sleep duration and quality are not associated with brown adipose tissue volume or activity—as determined by 18F-FDG uptake, in young, sedentary adults

Study Objectives: Short sleep duration and sleep disturbances have been related to obesity and metabolic disruption. However, the behavioral and physiological mechanisms linking sleep and alterations in energy balance and metabolism are incompletely understood. In rodents, sleep regulation is closely related to appropriate brown adipose tissue (BAT) thermogenic activity, but whether the same is true in humans has remained unknown. The present work examines whether sleep duration and quality are related to BAT volume and activity (measured by 18F-FDG) and BAT radiodensity in humans. Methods: A total of 118 healthy adults (69% women, 21.9 ± 2.2 years, body mass index: 24.9 ± 4.7 kg/m2) participated in this cross-sectional study. Sleep duration and other sleep variables were measured using a wrist-worn accelerometer for seven consecutive days for 24 hours per day. The Pittsburgh Sleep Quality Index was used to assess sleep quality. All participants then underwent a personalized cold exposure to determine their BAT volume, activity, and radiodensity (a proxy of the intracellular triglyceride content), using static positron emission tomography combined with computed tomography (PET/CI) scan. Results: Neither sleep duration nor quality was associated with BAT volume or activity (the latter represented by the mean and peak standardized 18F-FDG uptake values) or radiodensity (all p > .1). The lack of association remained after adjusting the analyses for sex, date of PET/CT, and body composition. Conclusions: Although experiments in rodent models indicate a strong relationship to exist between sleep regulation and BAT function, it seems that sleep duration and quality may not be directly related to the BAT variables examined in the present work