Large Groups of Unit of Integral Group Rings of Finite Nilpotent Groups

This paper surveys recent results regarding large subgroups of units in integral group rings of nilpotent groups, exibiting families of generators in several cases.nul

CP Violation and Arrows of Time Evolution of a Neutral KK or BB Meson from an Incoherent to a Coherent State

We study the evolution of a neutral $K$ meson prepared as an incoherent equal mixture of $K^0$ and $\bar{K^0}$. Denoting the density matrix by \rho(t) = {1/2} N(t) [\1 + \vec{\zeta}(t) \cdot \vec{\sigma} ] , the norm of the state $N(t)$ is found to decrease monotonically from one to zero, while the magnitude of the Stokes vector $|\vec{\zeta}(t)|$ increases monotonically from zero to one. This property qualifies these observables as arrows of time. Requiring monotonic behaviour of $N(t)$ for arbitrary values of $\gamma_L, \gamma_S$ and $\Delta m$ yields a bound on the CP-violating overlap $\delta = \braket{K_L}{K_S}$, which is similar to, but weaker than, the known unitarity bound. A similar requirement on $|\vec{\zeta}(t)|$ yields a new bound, $\delta^2 < {1/2} (\frac{\Delta \gamma}{\Delta m}) \sinh (\frac{3\pi}{4} \frac{\Delta \gamma}{\Delta m})$ which is particularly effective in limiting the CP-violating overlap in the $B^0$-$\bar{B^0}$ system. We obtain the Stokes parameter $\zeta_3(t)$ which shows how the average strangeness of the beam evolves from zero to $\delta$. The evolution of the Stokes vector from $|\vec{\zeta}| = 0$ to $|\vec{\zeta}| = 1$ has a resemblance to an order parameter of a system undergoing spontaneous symmetry breaking.Comment: 13 pages, 6 figures. Inserted conon "." in title; minor change in text. To appear in Physical review

Investigation of nose bluntness and angle of attack effects on slender bodies in viscous hypersonic flows

Hypersonic flows over cones and straight biconic configurations are calculated for a wide range of free stream conditions in which the gas behind the shock is treated as perfect. Effect of angle of attack and nose bluntness on these slender cones in air is studied extensively. The numerical procedures are based on the solution of complete Navier-Stokes equations at the nose section and parabolized Navier-Stokes equations further downstream. The flow field variables and surface quantities show significant differences when the angle of attack and nose bluntness are varied. The complete flow field is thoroughly analyzed with respect to velocity, temperature, pressure, and entropy profiles. The post shock flow field is studied in detail from the contour plots of Mach number, density, pressure, and temperature. The effect of nose bluntness for slender cones persists as far as 200 nose radii downstream

Seroprevalence of anti HCV antibodies among blood donors: a retrospective study from Haryana, India

Background: HCV is known for its chronicity and leads to cirrhosis in about 10 to 20 per cent of patients and may further progress to hepatocellular carcinoma (HCC). The global seroprevalence of HCV among blood donors varies from 0.4 to 19.2 per cent and the estimated risk for HCV transmission is between 0.10 to 2.33 per million units transfused. ELISA is the most commonly used initial assay for detecting HCV antibodies. The purpose of the present analysis was to monitor the seroprevalence of anti-HCV antibodies in the blood donor population in a hospital based blood bank in north India for a period of 10 years (2007-2016), and to evaluate the trends over the years.Methods: The purpose of the present analysis was to monitor the seroprevalence of anti-HCV antibodies in the blood donor population in a hospital based blood bank in north India for a period of 10 years (2007-2016), and to evaluate the trends over the years.Results: Of the total 340078, 298421 (87.75%) collections were voluntary and 41657 (12.25%) were replacement collections. A prevalence of 0.72% of hepatitis C virus infection was seen among the donors from the period 2007-2016. The trend of hepatitis C prevalence among donors has been fluctuating while ranging from 0.51% to 0.89%.Conclusions: For a safe blood service in our country, where comprehensive laboratory tests are neither possible nor pragmatic, it is best to switch over to 100% voluntary donations, as it is now established that only voluntary non-remunerated regular donation is the safest. Thus, one of our key strategies to enhance blood safety is to focus on motivating non-remunerated blood donors and phasing out even replacement donors. Since, no vaccine is presently available for immunization against HCV infection, transfusion transmitted HCV infection remains a potential threat to the safety of the blood supply

A retrospective analysis of trends of HIV and syphilis among blood donors in north India

Background: In India, it is mandatory to screen blood donors for HIV, hepatitis B, hepatitis C, syphilis and malaria. The donor screening strategies include taking the elaborate medical history, performing preliminary clinical examination and screening for infectious markers. The infectious markers include anti-HIV (1 and 2) antibodies, hepatitis B surface antigen (HBsAg), anti-hepatitis C virus antibodies, and malaria antigens, such as histidine rich protein (HRP) and pan-aldolase. National adult (15-49 years) HIV prevalence is estimated at 0.26% (0.22%-0.32%) in 20155 (0.30% among males and 0.22% among females). The objective of this study was to be carried out with the aim to find out the seroprevalence of HIV infection and its trend among the blood donors a hospital based blood transfusion service set up in north India over a period of six years.Methods: It was record based retrospective study from 2010 to 2015. Before donation "blood donation form" had been filled by every donor and this form had particulars about age, gender, address, and occupation, date of previous donation, any illness and medical treatment taken. The donor blood samples were collected at the time of blood donation from the primary bag and tested for the presence of HIV using enzyme linked immunosorbent assay (ELISA). All donors were subjected to a pre-test counselling which was done by qualified staff trained to screen donors for blood donation.Results: A prevalence of 0.21% of HIV was seen among the donors from the period 2010-2015. The trend of HIV prevalence among donors has been fluctuating while ranging from 0.13% to 0.34%.Conclusions: HIV remains the major threat for transfusion transmitted infections in India. For a safe blood service in our country, where comprehensive laboratory tests are neither possible nor pragmatic, it is best to switch over to 100% voluntary donations, as it is now established that only voluntary non-remunerated regular donation is the safest. Thus, one of our key strategies to enhance blood safety is to focus on motivating non-remunerated blood donors and phasing out even replacement donors