Inflaton Decay in an Alpha Vacuum

We study the alpha vacua of de Sitter space by considering the decay rate of the inflaton field coupled to a scalar field placed in an alpha vacuum. We find an {\em alpha dependent} Bose enhancement relative to the Bunch-Davies vacuum and, surprisingly, no non-renormalizable divergences. We also consider a modified alpha dependent time ordering prescription for the Feynman propagator and show that it leads to an alpha independent result. This result suggests that it may be possible to calculate in any alpha vacuum if we employ the appropriate causality preserving prescription.Comment: 16 pages, 1 figure, Revtex 4 preprin

Fetal malnutrition and adult chronic disease

Since the fetal origins of adult disease hypothesis was put forward, more than 30 studies around the world have indicated low-birth-weight (LBW) infants have a higher incidence of hypertension and impaired glucose tolerance. India ranks second in incidence of LBW among South East Asian countries and is experiencing a transition of disease pattern from communicable disease to non-communicable disease. Whether this could be explained in part by LBW infants who experienced better nutrition at a later age is explored here. An earlier cohort with accurate birth weights was traced and enrolled into the study. A sample of 50 LBW and 78 normal birth weight (NBW) individuals are reported on here. Though the odds ratio (OR) estimates of risk factors for coronary heart disease and diabetes tended to be higher in LBWs who were better nourished at the time of the study, they were not statistically different. Similarly, OR estimates for risk factors tended to be higher in LBWs who put on more weight than the median of NBWs, but they were not significant. Logistic regressions with several variables indicated significant influence of body mass index on systolic (P<0.007) and diastolic (P<0.004) blood pressures. Since the risk associations are weak, more studies are needed to put the hypothesis on a firm footing

Lagrangian subcategories and braided tensor equivalences of twisted quantum doubles of finite groups

We classify Lagrangian subcategories of the representation category of a twisted quantum double of a finite group. In view of results of 0704.0195v2 this gives a complete description of all braided tensor equivalent pairs of twisted quantum doubles of finite groups. We also establish a canonical bijection between Lagrangian subcategories of the representation category of a twisted quantum double of a finite group G and module categories over the category of twisted G-graded vector spaces such that the dual tensor category is pointed. This can be viewed as a quantum version of V. Drinfeld's characterization of homogeneous spaces of a Poisson-Lie group in terms of Lagrangian subalgebras of the double of its Lie bialgebra. As a consequence, we obtain that two group-theoretical fusion categories are weakly Morita equivalent if and only if their centers are equivalent as braided tensor categories.Comment: 26 pages; several comments and references adde

Timing Offset Calibration of CZTI instrument aboard ASTROSAT

The radio as well as the high energy emission mechanism in pulsars is yet not understood properly. A multi-wavelength study is likely to help in better understanding of such processes. The first Indian space-based observatory, ASTROSAT, has five instruments aboard, which cover the electromagnetic spectrum from infra-red (1300 $\AA$) to hard X-ray (380 KeV). Cadmium Zinc Telluride Imager (CZTI), one of the five instruments is a hard X-ray telescope functional over an energy range of 20-380 KeV. We aim to estimate the timing offset introduced in the data acquisition pipeline of the instrument, which will help in time alignment of high energy time series with those from two other ground-based observatories, viz. the Giant Meterwave Radio Telescope (GMRT) and the Ooty Radio Telescope (ORT). PSR B0531+21 is a well-studied pulsar with nearly aligned radio and hard X-ray pulse profiles. We use simultaneous observations of this pulsar with the ASTROSAT, the ORT and the GMRT. The pulsar was especially observed using the ORT with almost daily cadence to obtain good timing solutions. We also supplement the ORT data with archival FERMI data for estimation of timing noise. The timing offset of ASTROSAT instruments was estimated from fits to arrival time data at the ASTROSAT and the radio observatories. We estimate the offset between the GMRT and the ASTROSAT-CZTI to be -4716 $\pm$ 50 $\mu s$. The corresponding offset with the ORT was -29639 $\pm$ 50 $\mu s$. The offsets between the GMRT and Fermi-LAT -5368 $\pm$ 56 $\mu s$. (Abridged)Comment: 6 pages, 5 figures, 2 tables, Revised and Updated, accepted for publication in A&

Canine Parvovirus Isolates of India and the Relevance of Canine Parvovirus Type-2 Vaccines

A study was conducted to characterise the field isolates of canine parvovirus (CPV) and an in vitro cross neutralisation assay was performed against the vaccinated dog sera. Out of 45 faecal samples processed for virus isolation, 27 samples showed cytopathic effect (CPE) at first passage, which were confirmed positive by CPV variant types specific PCR. The CPV type 2 was not detected in any of the clinical samples. Of these 27 positive samples only 23 samples showed CPE and were further confirmed as CPV by haemagglutination inhibition test, ELISA and immuno-chromatographic strip test. Antigenic typing performed using a panel of monoclonal antibodies revealed that four of the 23 isolates were CPV 2b type and the remaining 19 isolates were typed as CPV 2a. The antigenic typing results obtained using the monoclonal antibodies corroborated the sequencing results reported by our group earlier. The cross neutralization study with polyclonal sera revealed that the sera of original antigenic type CPV 2 can neutralize the antigenic variants 2a and 2b effectively. Thus we conclude that the vaccines containing CPV type 2 virus can be used to immunise the dogs against the prevalent CPV 2a and CPV 2b infection. A live virus challenge study in dogs may further confirm this observation

Characterization of cucumber mosaic virus isolated from yam (Dioscorea spp.) in West Africa

Millions of people in the West African sub-region depend on yam for food and income. In 2008, cucumber mosaic virus (CMV), one of the most economically important plant viruses was detected in yam fields in Ghana, Benin and Togo, three of the five topmost yam producing countries in the world. Some strains of CMV are reportedly more virulent than others thus the need to characterise the strain isolated from yam. Sap inoculation of the yam strain induced systemic mosaic on Cucumis sativus and systemic chlorosis, necrotic lesions and leaf distortion on Nicotiana glutinosa. Sequence analysis of the 3' end of the coat protein gene and C-terminal noncoding region revealed 98 to 99, 93 to 98 and 78 to 79% nucleotide homology with members of the subgroups IA, IB and II, respectively. This analysis further revealed the absence of the EcoR1 restriction site characteristic of subgroup II strains and the presence of 15 nucleotide deletions dispersed along the C-terminal noncoding region of subgroup IA strains. At the amino acid level, the virus had 99 to 100% homology with subgroup I strains and 89% homology with subgroup II strains. Phylogenetic analysis of the amino acid confirms that the yam strain of CMV belongs to subgroup I while nucleotide sequence phylogeny confirms its placement in subgroup IA