Laser-Induced Skyrmion Writing and Erasing in an Ultrafast Cryo-Lorentz Transmission Electron Microscope.

We demonstrate that light-induced heat pulses of different duration and energy can write Skyrmions in a broad range of temperatures and magnetic field in FeGe. Using a combination of camera-rate and pump-probe cryo-Lorentz transmission electron microscopy, we directly resolve the spatiotemporal evolution of the magnetization ensuing optical excitation. The Skyrmion lattice was found to maintain its structural properties during the laser-induced demagnetization, and its recovery to the initial state happened in the sub-µs to µs range, depending on the cooling rate of the system.

Standing spin waves in ultrathin magnetic films: a method to test for layer-dependent exchange coupling.

We introduce a method to test theoretical models for the layer dependence of exchange coupling constants in ultrathin magnetic films. The method is based on the observation of high-energy and high-momentum standing spin wave modes using high-resolution electron energy loss spectroscopy. Experimental data are presented for 5-8 layers of fcc cobalt deposited on Cu(100). The power of the method is illustrated by comparison to two theoretical studies predicting rather different results concerning the ratio of the interlayer and intralayer exchange coupling constants near the surface. Only the theory with a large interlayer coupling shows sufficient energy spreading in the layer dependence of the dispersion curves to match the experimental data. We furthermore discuss the reason for the surprising success of the simple nearest-neighbor Heisenberg model with a single exchange constant matched to experiment.

Brain connectivity analysis based classification of obstructive sleep apnea using electroencephalogram signals.

Obstructive sleep apnea (OSA) is a disorder which blocks the upper airway during sleep. The severity of OSA will lead heart attack, stroke and end of life. This proposed study explored the classification of OSA and healthy subjects using brain connectivity analysis from electroencephalogram (EEG) signals. Institute of System and Robotics-University of Coimbra (ISRUC) database were used for acquiring 50 EEG signals using 4 channels and noise removal has been accomplished by 50 Hz notch filter. The Institute of System and Robotics-University of Coimbra (ISRUC) database contained 50 EEG signals, with four channels, and a 50 Hz notch filter was applied to remove noise. Wavelet packet decomposition method was performing the segregation of EEG signals into five bands; Gamma (γ), beta (ß), alpha (α), theta (θ) and delta (δ). A total of 4 electrode positions were used for the brain connectivity analysis for each EEG band. Pearson correlation method was effectively used for measuring the correlation between healthy and OSA subjects. The nodes and edges were highlighted the connection between brain and subjects. The highest correlation was achieved in delta band of OSA subjects which starts from 0.7331 to 0.9172 respectively. For healthy subjects, the positive correlation achieved was 0.6995. The delta band has been correlated well with brain when compared other bands. It has been noted that the positive correlation well associated with brain in OSA subjects, which classifies OSA from healthy subjects.

Aetiology and clinical profile of osteomalacia in adolescent girls in northern India.

BACKGROUND: The adolescent age group is particularly prone to nutritional rickets/osteomalacia due to an increased demand for nutrients, especially calcium and vitamin D. Osteomalacia presents with non-specific signs and symptoms because of which diagnosis may be delayed. Vitamin D deficiency is unexpected in India, which is a tropical country with abundant sunshine. METHODS: We prospectively studied the clinical presentation, aetiology and social factors contributing to adolescent rickets/ osteomalacia in our region. RESULTS: We saw 21 symptomatic adolescents with osteomalacia during the study period (November 2000-July 2002). All were girls. Only 1 practised purda and 4 belonged to a low socioeconomic class. The mean (SD) duration of illness before correct diagnosis was 2.8 (2.1) years. Bone pains and muscular weakness were universally present. Non-specific complaints (especially limb pains being mistaken for joint involvement) led to a delay in diagnosis with consequent morbidity. All but 1 patient had low serum 25-hydroxyvitamin D levels (<10 ng/ml), with the mean (SD) being 4.9 (2.7) ng/ml. Their mean dietary calcium intake was low 1265 (199) mg/day, range 40-810 mg/day]. Restricted outdoor activities (n = 19) and the traditional dress code (n = 21) were contributory factors, as they led to poor exposure to sunshine. CONCLUSIONS: Nutritional osteomalacia among adolescents is a poorly recognized entity. Even in non-purda practising communities in the tropics, poor exposure to sunshine due to social factors, compounded by low dietary calcium intake, can lead to osteomalacia in adolescents.

Study of the knowledge, beliefs, and practice of sleep among medical undergraduates of Tamilnadu, India.

CONTEXT: Sleep-related problems are common in young adults who are enrolled in professional colleges due to academic and social pressures, which may subsequently have serious consequences. OBJECTIVES: This study was conducted to find out whether final-year medical undergraduates possess basic, clinically relevant knowledge (K) regarding sleep and sleep-related problems and to discover their beliefs (B) regarding sleep and sleep hygiene. We also wanted to assess their sleep practices (P) and suggest remedial measures, if necessary. DESIGN AND SETTING: Six hundred fifteen final-year medical undergraduates of both sexes belonging to 6 medical colleges of Tamilnadu state, India, were given a self-administered, anonymous questionnaire to test their basic knowledge (11 items), prevailing beliefs regarding sleep (including sleep hygiene [13 items]), and their sleep practices (6 items). RESULTS: In all 3 domains tested (K, B, and P), there was no significant difference between sex. An appreciable percentage scored < or = 70% marks ("good") only in K and P (63.9% and 79.5% of all participants, respectively), whereas only a very small percentage scored "good" in B (9.1%). There was no difference in K, B, or P in terms of sex or domiciliary status except for a significant difference (P < .012) regarding beliefs between urban and rural groups. There was also no correlation between knowledge and beliefs or between knowledge and practice. CONCLUSION: We conclude that future doctors have insufficient knowledge with more misconceptions (indirectly reflecting inadequate knowledge) regarding sleep. Hence, there is a compelling need to develop an educational strategy to overcome misconceptions and improve knowledge regarding sleep-related problems and proper sleep practices among students.

An electron energy loss spectrometer designed for studies of electronic energy losses and spin waves in the large momentum regime.

Based on 143° electrostatic deflectors we have realized a new spectrometer for electron energy loss spectroscopy which is particularly suitable for studies on surface spin waves and other low energy electronic energy losses. Contrary to previous designs high resolution is maintained even for diffuse inelastic scattering due to a specific management of the angular aberrations in combination with an angle aperture. The performance of the instrument is demonstrated with high resolution energy loss spectra of surface spin waves on a cobalt film deposited on the Cu(100) surface.

Necrotizing fasciitis: a case of hip disarticulation in a postnatal intravenous drug abuser.

An interesting case of necrotizing fasciitis of the leg following emergency caesarian section in a known intravenous drug user. Postnatal day two she developed pain and swelling in the left leg. In view of her previous history, deep vein thrombosis (DVT) was the initial diagnosis. But, due to clinically worsening symptoms and no response to anticoagulation, further investigations were done which showed necrotizing fasciitis. Due to disease progression, a hip disarticulation was performed and the patient went on to full recovery.

Direct association between caspase 3 and alpha5beta1 integrin and its role during anoikis of rat fibroblasts.

We have demonstrated a direct association between alpha5beta1 integrin and caspase 3, both pro- and mature enzyme, in various sub-cellular compartments of rat fibroblasts undergoing anoikis. Integrin associated caspase 3 showed high activity in the plasma membranes, whereas in the cytosol and microsomal fraction it showed little or no activity. Our results suggest a possible role for recycled un-ligated alpha5beta1 integrin molecules between cytosol and plasma membrane, in regulation of caspase-3 activity and induction of cell death in adhesion-deprived cells.

The significance of alpha 5 beta 1 integrin dependent and independent actin cytoskelton organization in cell transformation and survival.

Cell-matrix and cell-cell interactions are important physiological determinants of cell growth, survival and transformation. Cell adhesion to the extra cellular matrix (ECM) via integrins also crucially influences the organization of the cytoskeleton. It triggers a cascade of intracellular biochemical events, which regulate cell viability and growth. We have studied the relationship between cell attachment to the substratum and cytoskeletal organization and cell survival and transformation. Our results demonstrate that in the absence of attachment to the substratum, adhesion-dependent fibroblasts exhibit rapid loss of viability. However, a small percentage of cells survive even after remaining non-adherent for 16h. The adherent and non-adherent cells differ from one another both morphologically and physiologically. The latter show a loss of alpha5beta1 integrin expression on their surface and bind non-specifically to the substratum and ECM, thereby activating certain pathways more efficiently than adherent cells. We have also shown that non-adherent cells grow faster and have worse cytoskeletal organization after attachment to the substratum, and do not form focal adhesions or actin stress fibres. Hence, our data suggests that rat fibroblasts in prolonged suspension exhibit some properties that are comparable to cells undergoing transformation, by adapting integrin-dependent or independent signalling pathways for their survival.

Varying role of vitamin D deficiency in the etiology of rickets in young children vs. adolescents in northern India.

The relative importance of calcium vs. vitamin D deficiency in the etiology of nutritional rickets in the tropics may be different in children compared with adolescents. We studied calcium intake, sun exposure, serum alkaline phosphatase, and 25 hydroxyvitamin D in 24 children and 16 adolescents with rickets/osteomalacia. The values were compared with those obtained in control subjects (34 children and 19 adolescents). We found that young children with rickets had lower calcium intake compared with controls (285 +/- 113 vs. 404 +/- 149 mg/day, p < 0.01), but similar sun exposure (55 +/- 28 vs. 56 +/- 23 min x m2/day) and 25 hydroxyvitamin D (49 +/- 38 vs. 61 +/- 36 nmol/l). Sixteen of 24 children with rickets had 25 hydroxyvitamin D above the rachitic range (> 25 nmol/l), in contrast to one of 16 adolescents. Adolescent patients had low calcium intake vs. controls (305 +/- 196 vs. 762 +/- 183 mg, p < 0.001), and lower sunshine exposure (16 +/- 15 vs. 27 +/- 17 min x m2/day, p < 0.01) and serum 25 hydroxyvitamin D (12.6 +/- 7.1 vs. 46 +/- 45.4 nmol/l, p < 0.001). The odds ratio for developing rickets with a daily calcium intake below 300 mg was 4.8 (95 per cent CI, 1.9 - 12.4, p = 0.001). Subjects with rickets were randomized to receive 1 g calcium daily, with or without vitamin D. Children showed complete healing in 3 months, whether they received calcium alone or with vitamin D. Adolescents showed no response to calcium alone, but had complete healing with calcium and vitamin D in 3-9 months (mean 5.3 months). Thus deficient calcium intake is universal among children and adolescents with rickets/osteomalacia. Inadequate sun exposure and vitamin D deficiency are important in the etiology of adolescent osteomalacia.