Metal-Semiconductor-Metal GeSn Photodetectors on Silicon for Short-Wave Infrared Applications.

Metal-semiconductor-metal photodetectors (MSM PDs) are effective for monolithic integration with other optical components of the photonic circuits because of the planar fabrication technique. In this article, we present the design, growth, and characterization of GeSn MSM PDs that are suitable for photonic integrated circuits. The introduction of 4% Sn in the GeSn active region also reduces the direct bandgap and shows a redshift in the optical responsivity spectra, which can extend up to 1800 nm wavelength, which means it can cover the entire telecommunication bands. The spectral responsivity increases with an increase in bias voltage caused by the high electric field, which enhances the carrier generation rate and the carrier collection efficiency. Therefore, the GeSn MSM PDs can be a suitable device for a wide range of short-wave infrared (SWIR) applications.

Resonant-cavity-enhanced responsivity in germanium-on-insulator photodetectors.

The germanium-on-insulator (GOI) has recently emerged as a new platform for complementary metal-oxide-semiconductor (CMOS)-compatible photonic integrated circuits. Here we report on resonant-cavity-enhanced optical responses in Ge photodetectors on a GOI platform where conventional photodetection is difficult. A 0.16% tensile strain is introduced to the high-quality Ge active layer to extend the photodetection range to cover the entire range of telecommunication C- and L-bands (1530-1620 nm). A carefully designed vertical cavity is created utilizing the insulator layer and the deposited SiO2 layer to enhance the optical confinement and thus optical response near the direct-gap absorption edge. Experimental results show a responsivity peak at 1590 nm, confirming the resonant cavity effect. Theoretical analysis shows that the optical responsivity in the C- and L-bands is significantly enhanced. Thus, we have demonstrated a new type of Ge photodetector on a GOI platform for CMOS-compatible photonic integrated circuits for telecommunication applications.

Typhoid fever: Control & challenges in India.

Enteric fever is a common but serious disease that affects mostly children and adolescents in the developing countries. Salmonella enterica serovar Typhi remains responsible for most of the disease episodes; however, S. Paratyphi A has also been reported as an emerging infectious agent of concern. The control measures for the disease must encompass early diagnosis, surveillance and vaccine to protect against the disease. Sanitation and hygiene play a major role in reducing the burden of enteric diseases as well. The current status of diagnostics, the surveillance practices in the recent past and the vaccine development efforts have been taken into account for suggesting effective prevention and control measures. However, the challenges in all these aspects persist and cause hindrance in the implementation of the available tools. Hence, an integrative approach and a comprehensive policy framework are required to be in place for the prevention, control and elimination of typhoid fevers.

A Retrospective Review of Hospital-Based Data on Enteric Fever in India, 2014-2015.

Background: Enteric fever remains a threat to many countries with minimal access to clean water and poor sanitation infrastructure. As part of a multisite surveillance study, we conducted a retrospective review of records in 5 hospitals across India to gather evidence on the burden of enteric fever. Methods: We examined hospital records (laboratory and surgical registers) from 5 hospitals across India for laboratory-confirmed Salmonella Typhi or Salmonella Paratyphi cases and intestinal perforations from 2014-2015. Clinical data were obtained where available. For laboratory-confirmed infections, we compared differences in disease burden, age, sex, clinical presentation, and antimicrobial resistance. Results: Of 267536 blood cultures, 1418 (0.53%) were positive for S. Typhi or S. Paratyphi. Clinical data were available for 429 cases (72%); a higher proportion of participants with S. Typhi infection were hospitalized, compared with those with S. Paratyphi infection (44% vs 35%). We observed resistance to quinolones among 82% of isolates, with cases of cephalosporin resistance (1%) and macrolide resistance (9%) detected. Of 94 participants with intestinal perforations, 16 (17%) had a provisional, final, or laboratory-confirmed diagnosis of enteric fever. Discussion: Data show a moderate burden of enteric fever in India. Enteric fever data should be systematically collected to facilitate evidence-based decision-making by countries for typhoid conjugate vaccines.

The cell based therapy and the policy implications in India.

The recent scientific development using stem or other differentiated cells has generated great hopes for treatment of various diseases. Major thrust has been given to formulate country specific laws and regulations considering international guidelines to conduct research and clinical applications of "Cell Based Therapy" (CBT) all over the world. Attempts have made in this review to discuss the current policies that are practiced by various countries in the areas related to CBT with special emphasis on CBT related research and development in India. The two major funding agencies of Government of India e.g. Department of Biotechnology (DBT) and Indian Council of Medical Research (ICMR), have jointly formulated the "Guidelines for Stem Cell Research and Therapy" in 2007 which requires update and revision. Based on the review of the current world scenario of CBT research and development, suggestions have been made for the development of a new CBT policy that will help in progress of research and patient treatment in India.