Reversal of Klein reflection in bilayer graphene

Whereas massless Dirac fermions in monolayer graphene exhibit Klein tunneling when passing through a potential barrier upon normal incidence, such a barrier totally reflects massive Dirac fermions in bilayer graphene due to difference in chirality. We show that, in the presence of magnetic barriers, such massive Dirac fermions can have transmission through even at normal incidence. The general consequence of this behaviour for multilayer graphene consisting of massless and massive modes are mentioned. We also briefly discuss the effect of a bias voltage on such magnetotransport.Comment: 10 double space single column latexed pages, 15 eps files in four figure

A Green's function approach to transmission of massless Dirac fermions in graphene through an array of random scatterers

We consider the transmission of massless Dirac fermions through an array of short range scatterers which are modeled as randomly positioned $\delta$- function like potentials along the x-axis. We particularly discuss the interplay between disorder-induced localization that is the hallmark of a non-relativistic system and two important properties of such massless Dirac fermions, namely, complete transmission at normal incidence and periodic dependence of transmission coefficient on the strength of the barrier that leads to a periodic resonant transmission. This leads to two different types of conductance behavior as a function of the system size at the resonant and the off-resonance strengths of the delta function potential. We explain this behavior of the conductance in terms of the transmission through a pair of such barriers using a Green's function based approach. The method helps to understand such disordered transport in terms of well known optical phenomena such as Fabry Perot resonances.Comment: 22 double spaced single column pages. 15 .eps figure

Pseudo (Platelet-type) von Willebrand disease in pregnancy: a case report

Abstract Background Pseudo (platelet-type)-von Willebrand disease is a rare autosomal dominant bleeding disorder caused by an abnormal function of the glycoprotein lb protein; the receptor for von Willebrand factor. This leads to an increased removal of VWF multimers from the circulation as well as platelets and this results in a bleeding diathesis. Worldwide, less than 50 patients are reported with platelet type von Willebrand disease (PT-VWD). Case presentation We describe the management of platelet type von Willebrand disease in pregnancy of a 26 year old Caucasian primigravida. The initial diagnosis was made earlier following a significant haemorrhage post tonsillectomy several years prior to pregnancy. The patient was managed under a multidisciplinary team which included obstetricians, haematologists, anaesthetists and neonatologists. Care plans were made for the ante- natal, intra-partum and post-partum periods in partnership with the patient. The patient’s platelet count levels dropped significantly during the antenatal period. This necessitated the active exclusion of other causes of thrombocytopenia in pregnancy. A vaginal delivery was desired and plans were made for induction of labour at 38 weeks of gestation with platelet cover in view of the progressive fall of the platelet count. The patient however went into spontaneous labour on the day of induction. She was transfused two units of platelets before delivery. She had an unassisted vaginal delivery of a healthy baby. The successful antenatal counselling has encouraged the diagnosis of the same condition in her mother and sister. We found this to be a particularly interesting case as well as challenging to manage due to its rarity. Psuedo von Willebrand disease in pregnancy can be confused with a number of other differential diagnoses, such as gestational thrombocutopenia, idiopathatic thrombocytopenia, thrombotic thrombocytopenic purpura and pre-eclampsia; all need consideration during investigations even in a case such as this where the diagnosis of platelet type von Willebrand disease was known before pregnancy. Conclusion Management of pseudo von Willebrand disease in pregnancy involves the co-operation of multidisciplinary teams, regular monitoring of platelet levels and factor VIII and replacement as appropriate. This case report highlights this rare condition and the need to exclude all the other differential diagnoses of thrombocytopenia in pregnant women with thrombocytopenia.</p

Retaining health workforce in rural and underserved areas of India: What works and what doesn't? A critical interpretative synthesis

Background. Human resource for health is critical in quality healthcare delivery. India, with a large rural population (68.8%), needs to urgently bridge the gaps in health workforce deployment between urban and rural areas.Methods. We did a critical interpretative synthesis of the existing literature by using a predefined selection criteria to assess relevant manuscripts to identify the reasons for retaining the health workforce in rural and underserved areas. We discuss different strategies for retention of health workforce in rural areas on the basis of four major retention interventions, viz. education, regulation, financial incentives, and personal and professional support recommended by WHO in 2010. This review focuses on the English-language material published during 2005-14 on human resources in health across low and middle-income countries.Results. Healthcare in India is delivered through a diverse set of providers. Inequity exists in health manpower distribution across states, area (urban rural), gender and category of health personnel. India is deficient in health system development and financing where health workforce education and training occupy a low priority. Poor governance, insufficient salary and allowances, along with inability of employers to provide safe, satisfying and rewarding work conditions are causing health worker attrition in rural India. The review suggests that the retention of health workers in rural areas can be ensured by multiplicity of interventions such as medical schools in rural areas, rural orientation of medical education, introducing compulsory rural service in lieu of incentives providing better pay packages and special allowances, and providing better living and working conditions in rural areas.Conclusions. A complex interplay of factors that impact on attraction and retention of health workforce necessitates bundling of interventions. In low-income countries, evidence based strategies are needed to ensure context-specific, field-tested and cost-effective solutions to various existing problems. To ensure retention these strategies must be integrated with effective human resource management policies and rural orientation of the medical education system

Endoscopic management of foreign bodies from the upper gastrointestinal tract in the hills of Himachal Pradesh, India: A 5-year tertiary care experience

Background and Aim: Foreign body (FB) ingestion is a common clinical problem in medical practice. Endoscopy is the therapeutic method of choice for the management of FBs with minimal complications. The aim of this study is to report our experience and outcome in a 5-year period in dealing with FBs in the upper gastrointestinal tract (GIT) using upper endoscopy. Materials and Methods: The records of all the patients who presented to the Department of Gastroenterology and who underwent endoscopic management between January, 2010, and December, 2014, were reviewed with details on age, sex, type of FBs and its anatomical location, treatments, and outcomes. Results: A total of 59 patients were analyzed. Their age ranged from 2 years to 87 years. A male predominance was noticed (59.4%). Coins and chicken bone shared the most commonly encountered FBs. Esophagus was the most common site of trapping (49/59). Upper endoscopy successfully resolved the problem by FB removal in all patients, thus the overall success rate was 100%. No complications or mortalities due to FB ingestion or removal were observed throughout the study. Conclusion: In our experience, endoscopic management of FBs in upper GIT is a safe and highly effective procedure