Angle-dependent carrier transmission in graphene p-n junctions.

Angle-dependent carrier transmission probability in graphene p-n junctions is investigated. Using electrostatic doping from buried gates, p-n junctions are formed along graphene channels that are patterned to form different angles with the junction. A peak in the junction resistance is observed, which becomes pronounced with angle. This angular dependence is observed for junctions made on both exfoliated and CVD-grown graphene and is consistent with the theoretically predicted dependence of transmission probability on incidence angle.

DEVELOPMENT OF OPTICALLY STIMULATED LUMINESCENCE BADGE READER SYSTEM FOR INDIVIDUAL MONITORING OF RADIATION WORKERS.

A new Optically Stimulated Luminescence Badge Reader (OSBARE-1) system has been designed and developed for application in the individual monitoring dosimetry. This badge reader system utilizes the 470-nm light of a blue LED for CW-OSL readout with the help of PMT photon counting module. The developed reader system can process four element 24 OSLD cards within 25 min. These four-element OSLD card consists of the Teflon embedded indigenously developed dosimetric grade α-Al2O3:C phosphor. The minimum measurable dose (MMD) was found to be ~26 µGy for these OSLD cards with reproducibility of ~1.12%. The various operational parameters such as variation in the dark counts, OSL scattering background counts and reproducibility have been studied in detailed for this reader system. The dosimetric studies performed on this developed reader system found to have a great potential for the OSLD-based large-scale personnel monitoring program for the radiation workers.

Outcome of universal newborn eye screening with wide-field digital retinal image acquisition system: a pilot study.

PurposeTo evaluate the outcome of universal newborn eye screening with wide-field digital retinal imaging (WFDRI) system.MethodsIn this pilot study, we examined 1152 apparently healthy newborn infants in the obstetrics and gynecology ward of a civil hospital in Eastern India over 1.5 years. The examination included external eye examination, red reflex test and fundus imaging by WFDRI (RetCam II, Clarity medical system, Pleasanton, CA, USA) by a trained optometrist. The pathologies detected, net monetary gain and skilled manpower saved were documented. The results were compared with three similar studies thus far published in the literature.ResultsOcular abnormality of any kind was seen in 172 (14.93%) babies. Retinal hemorrhage in 153 babies (88.9% of all abnormal findings) was the most common abnormality; it was bilateral in 118 (77.12%) babies and 4 babies had foveal hemorrhage. Other abnormalities included vitreous hemorrhage (n=1), congenital glaucoma (n=2), uveal coloboma (n=2), retinopathy mimicking retinopathy of prematurity (n=2), and cystic fovea (n=3). The retinal hemorrhages resolved spontaneously in all eyes. One baby with congenital glaucoma received surgery and the other was treated medically. The benefits included savings in skilled manpower, a net monetary gain of INR 4.195 million (US$ 62,612) and skilled manpower saving by 319.4 h.ConclusionsThe universal neonatal eye screening using WFDRI detected pathologies that needed immediate care or regular follow up; saved skilled manpower with a net monetary gain. But compared to a red reflex test the benefits were marginal in terms of detecting treatment warranting ocular pathologies.

Serial evaluation of retinal vascular changes in infants treated with intravitreal bevacizumab for aggressive posterior retinopathy of prematurity in zone I.

PURPOSE: To evaluate the serial changes in retinal vasculature in infants treated with intravitreal bevacizumab (IVB) for aggressive posterior retinopathy of prematurity (APROP) in zone I. METHODS: Retrospective analysis of serial changes in retinal vasculature after IVB in the seven eyes of four babies with APROP in zone I. RESULTS: The initial regression, following IVB, was dramatic with reduction in vessel caliber and marked thinning and invisibility of the bridging shunts. Resurgent vascular development was very slow radially though there was continued abnormal vascular growth circumferentially. Common findings in all eyes were tangled vasculature and fine saw-toothed shunts. The variable findings were (1) new closely packed multilayered bridging shunts, long arching mature looking vessels, and finally a ridge at the periphery (n=3 eyes) at 52 weeks of postmenstrual age (PMA); (2) status quo at the stage of saw-toothed shunt and ridge in both eyes for a long time (n=2 eyes); and (3) multiple retinal hemorrhages within the vascularized retina and thick preretinal hemorrhage overlying the saw-toothed shunts and ridge that persisted for another 3 weeks and regressed 2 weeks after laser (n=1). The eyes that received bevacizumab alone (3) did not show any abnormal vascularization at 56 weeks of PMA or beyond. CONCLUSIONS: The retinal vascularization following IVB was different than normal in terms of its time, speed, and morphology; few of these changes are first to be reported in the literature (Medline search) and warrants further studies.

Feasibility of voluntary counselling and testing services for HIV among pregnant women presenting in labour in Pune, India.

Factors affecting the eligibility and acceptability of voluntary counselling and rapid HIV testing (VCT) were examined among pregnant women presenting in labour in Pune, India. Of the 6702 total women appearing at the delivery room from April 2001 to March 2002, 4638 (69%) were admitted for normal delivery. The remaining women presented with obstetrical complications, delivered immediately or were detected to be in false labour. Overall, 2818 (61%) of the admitted women had been previously tested for HIV during their pregnancy. If previously seen in the hospital's affiliated antenatal clinic, the likelihood of being previously tested was 89%, in contrast to 27% of women having prenatal care elsewhere. Of the admitted women, 3436 (74.3%) were assessed for their eligibility for rapid HIV VCT in the delivery room. Only 1322 (38%) of these women were found to be in early labour and without severe pain or complications, and therefore eligible for rapid HIV screening in the delivery room (DR). Of those 1322 eligible women, only 582 (44%) consented and were tested for HIV, of whom nine (1.6%) were found to be HIV-infected. Of the 1674 women arriving in the DR with no evidence of previous HIV testing, through this DR screening programme, we identified four women with HIV who could now benefit from treatment with ART. Given the high rates of HIV testing in the antenatal clinic at this site and the challenges inherent to conducting DR screening, alternatives such as post-partum testing should be considered to help reduce maternal to infant transmission in this population.

Evaluation of retinopathy of prematurity screening in reverse Kangaroo Mother Care: a pilot study.

PURPOSE: To evaluate retinopathy of prematurity (ROP) screening practice in reverse Kangaroo Mother Care (R-KMC) with respect to stress and pain to the infant. METHODS: In a pilot study we evaluated ROP screening practice in R-KMC in 20 babies at risk of ROP. The R-KMC differed from the conventional KMC with respect to the baby position where the baby lay supine on mother's chest. With the mother lying supine and the baby in R-KMC position, screening examinations were done with indirect ophthalmoscope. The outcome measures included stress (quantified by pulse, respiration, and oxygen saturation) and pain to the baby by observing facial expression (eye squeezing, crying, and brow bulge). The heart rate, respiratory rate, and SpO2 (%) were compared before and immediately after the procedure using paired t-test. RESULT: Mean (±SD) gestational age and birth weight were 30.8±2.3 weeks and 1362.5±253.9 g, respectively. During examination in R- KMC position 8 babies (40%) were completely relaxed (no eye squeezing and crying), 10 (50%) were partially relaxed (no brow bulge) and 2 babies (10%) were not relaxed. A change in heart and respiration rate both by 10 per minute was recorded in 12 (60%) and 10 (50%) babies, respectively. Five babies (25%) had reduction in blood oxygen concentration below 92%. The majority of the mothers (19 of 20) were relaxed. CONCLUSION: ROP screening in R-KMC can be a baby friendly screening practice with respect to stress and pain to the infant and needs further evaluation in a larger cohort.

Optimizing the HIV/AIDS informed consent process in India.

BACKGROUND: While the basic ethical issues regarding consent may be universal to all countries, the consent procedures required by international review boards which include detailed scientific and legal information, may not be optimal when administered within certain populations. The time and the technicalities of the process itself intimidate individuals in societies where literacy and awareness about medical and legal rights is low. METHODS: In this study, we examined pregnant women's understanding of group education and counseling (GEC) about HIV/AIDS provided within an antenatal clinic in Maharashtra, India. We then enhanced the GEC process with the use of culturally appropriate visual aids and assessed the subsequent changes in women's understanding of informed consent issues. RESULTS: We found the use of visual aids during group counseling sessions increased women's overall understanding of key issues regarding informed consent from 38% to 72%. Moreover, if these same visuals were reinforced during individual counseling, improvements in women's overall comprehension rose to 96%. CONCLUSIONS: This study demonstrates that complex constructs such as informed consent can be conveyed in populations with little education and within busy government hospital settings, and that the standard model may not be sufficient to ensure true informed consent.

Awareness of HIV/AIDS and household environment of pregnant women in Pune, India.

Our objective was to determine the level of HIV/AIDS knowledge of pregnant women in India. In a sub-sample of these women, we documented the extent to which they experienced adverse social and physical difficulties within their home. The study was performed at an urban antenatal hospital clinic in Maharastra, India. From April to September 2001, structured interviews were conducted on 707 randomly selected antenatal clinic patients related to HIV/AIDS knowledge. Of these, 283 were further interviewed to document any social or physical difficulties they experienced. Over 75% of women displayed knowledge of primary transmission routes. Nearly 70% of women demonstrated knowledge of maternal to child transmission, however, only 8% knew of any methods of prevention. TV and written material were more strongly related to knowledge than access to radio messages or conversations with individuals. Thirty per cent of the women experienced physical or mental abuse or their spouse's alcohol and/or drug problems. Women reporting such abuse were more than twice as likely to have adequate HIV/AIDS knowledge compared with women reporting no such abuse. We found no relationship between reported household abuse and educational level of woman, husband, occupation of either partner, language or religion. We found no relationship between HIV status and knowledge of HIV and no relationship between HIV status and risk of abuse in the household. However, the total number of HIV patients in our sample was very small.

In vitro Evaluation of Novel Sustained Release Microspheres of Glipizide Prepared by the Emulsion Solvent Diffusion-Evaporation Method.

The objective of the current investigation is to reduce dosing frequency and improve patient compliance by designing and systematically evaluating sustained release microspheres of Glipizide. An anti-diabetic drug, Glipizide, is delivered through the microparticulate system using ethyl cellulose as the controlled release polymer. Microspheres were developed by the emulsion solvent diffusion-evaporation technique by using the modified ethanol,-dichloromethane co-solvent system. The polymer mixture of ethyl cellulose and Eudragit(®) S100 was used in different ratios (1:0, 1:1, 2:3, 1:4 and 0:1) to formulate batches F1 to F5. The resulting microspheres were evaluated for particle size, densities, flow properties, morphology, recovery yield, drug content, and in vitro drug release behavior. The formulated microspheres were discrete, spherical with relatively smooth surface, and with good flow properties. Among different formulations, the fabricated microspheres of batch F3 had shown the optimum percent drug encapsulation of microspheres and the sustained release of the Glipizide for about 12 h. Release pattern of Glipizide from microspheres of batch F3 followed Korsmeyers-peppas model and zero-order release kinetic model. The value of 'n' was found to be 0.960, which indicates that the drug release was followed by anomalous (non-fickian) diffusion. The data obtained thus suggest that a microparticulate system can be successfully designed for sustained delivery of Glipizide and to improve dosage form characteristics for easy formulation.