Intra-night Optical Variability of Luminous Radio Quiet QSOs

In the present paper we report the detection of intra-night variability in some of the RQQSOs and one LDQ. To study intra-night variability, we carried out photometric monitoring of seven RQQSOs and one LDQ in Johnson V-passband using 1.2 meter optical/IR telescope at Gurushikhar, Mount Abu, India. Observations were made in nine nights during the first half of the year 2000; seven RQQSOs: 0748+291, 0945+438, 1017+280, 1029+329, 1101+319, 1225+317, 1252+020 and one LDQ: 1103-006 were observed. RQQSOs 0748+291, 1225+317 and LDQ 1103-006 have shown existence of intra-night variations. In the case of 1017+280 (RQQSO) there is indication of intra-night variation in one night where as the observations in another night do not show convincingly the existence of intra-night variability. RQQSOs 0945+438, 1029+329, 1101+319 and 1252+020 have not shown any intra-night variations. We compiled intra-night variability data for radio-loud and radio-quiet AGNs from the literature for statistical analysis. It is found that a good fraction of radio-quiet AGNs show intra-night variations with the maximum amplitude of variation being about 10%. On the other hand blazars show at times intra-night flux variability up to 100%. In case of radio-loud AGNs (excluding blazars), maximum amplitude of intra-night variation lies between the variability amplitude of radio-quiet AGNs and blazars i.e. the flux variation is close to 50%. The results indicate that the energy generation mechanism and the environment around the central engine in different classes of AGNs may be similar, if not identical. The standard model for radio-loud AGNs, where shocks are propagating down relativistic jet or models based on disturbances in accretion disks can also explain the micro-variability in RQQSOs.Comment: 12 pages, 12 figures, Accepted for publication in A & A, uses aa.cl

Queue Length and Server Content Distribution in an Infinite-Buffer Batch-Service Queue with Batch-Size-Dependent Service

We analyze an infinite-buffer batch-size-dependent batch-service queue with Poisson arrival and arbitrarily distributed service time. Using supplementary variable technique, we derive a bivariate probability generating function from which the joint distribution of queue and server content at departure epoch of a batch is extracted and presented in terms of roots of the characteristic equation. We also obtain the joint distribution of queue and server content at arbitrary epoch. Finally, the utility of analytical results is demonstrated by the inclusion of some numerical examples which also includes the investigation of multiple zeros

Occurrence of Streptomyces aurantiacus in Mangroves of Bhitarkanika

Thirteen strains of Streptomyces were isolated from phyllosphere of nine mangrove tree species found in Bhitarkanika mangrove ecosystem of Orissa. According to physiological, biochemical data, all 13 of the isolates were taxonomically identified to the genus Streptomyces as aurantiacus species. All strains are grayish, spirals and forming amorphous colony. Almost all utilized araginose, produced H2S, resistant towards rifampicin and penicillin, urea except few strains. However, they exhibited different extracellular activity like phosphate solubilization, lipase and L asparaginase production. This is a unique report from this mangrove ecosystem as far as Streptomyces occurrence is concerned

Micronutrients in Grassland Production

Micronutrients, also known as trace minerals, which chiefly include boron (B), molybdenum (Mo), copper (Cu), zinc (Zn), manganese (Mn) and iron (Fe), are required in extremely small quantities by crops and livestock. Their name, however, is not meant to imply their role is minor. Their lack, e.g., can cause serious crop production problems in forages and health disorders in livestock. This presentation includes the response of forage legumes and grasses to micronutrients, their deficiency and sufficiency levels in forages and their sufficiency levels in livestock. Forage legumes are more responsive to micronutrients, particularly B and Mo, than grasses. There are fewer documented cases of Cu, Fe, Mn and Zn deficiencies than of B and Mo deficiencies in forages. Soil acidity is one of the primary factors affecting the availability of micronutrients to forages. Low soil pH, e.g., is the principal cause of Mo deficiency in soybeans in Brazil and in a variety of crops in eastern Canada. More often soil properties and environmental factors are more important than actual soil levels, in affecting micronutrient availability. Micronutrient deficiencies have been emerging as a major problem in intensively cultivated soils in many countries and have become one of the serious constraints to crop productivity. Deficiency symptoms for most micronutrients appear on the young leaves at the top of the plant, because most of these nutrients are not readily translocated. However, Mo is an exception in that it is readily translocated, and its deficiency symptoms generally appear on the whole plant. Toxicity symptoms, on the other hand, for most micronutrients appear on the older leaves of the plant which is very striking, e.g., for B. Soil, foliar and seed applied methods of micronutrient application to control their deficiency are discussed in detail. Frequently the Cu, Fe, Mn, Zn and Se levels in forages which are sufficient for optimum crop yields are not adequate to meet the needs of livestock. Selenium is a trace mineral which is not required by plants and maximum forage yields can be obtained on soils with very low amounts of soil Se. However, if animals are fed forage with low Se, they could suffer from serious muscular disorders and other diseases. White muscle disease caused due to Se deficiency is the most common disorder and is found in calves and lambs. Sufficiency levels of micronutrients for crops have been discussed in relation to the animal requirement

A queueing system with batch renewal input and negative arrivals

This paper studies an infinite buffer single server queueing model with exponentially distributed service times and negative arrivals. The ordinary (positive) customers arrive in batches of random size according to renewal arrival process, and joins the queue/server for service. The negative arrivals are characterized by two independent Poisson arrival processes, a negative customer which removes the positive customer undergoing service, if any, and a disaster which makes the system empty by simultaneously removing all the positive customers present in the system. Using the supplementary variable technique and difference equation method we obtain explicit formulae for the steady-state distribution of the number of positive customers in the system at pre-arrival and arbitrary epochs. Moreover, we discuss the results of some special models with or without negative arrivals along with their stability conditions. The results obtained throughout the analysis are computationally tractable as illustrated by few numerical examples. Furthermore, we discuss the impact of the negative arrivals on the performance of the system by means of some graphical representations.Comment: 12 pages, 5 Figures, conferenc

Exploitation of juveniles of the spinycheek grouper, Epinephelus diacanthus by multiday trawlers along Dakshina Kannada coast

The juveniles in the size range 9-24 cm are in sizeable quantities during October - May at Mangalore and Malpe landing centres of Dakshina Kannada coast. The present study is undertaken to highlight the magnitude of the exploitation of the juveniles of the Spinycheek grouper. Epinephelus diacanthus by trawlers along the Dakshina Kannada coast and its impact on the stock with a brief description on its biology. This species is known to grow to a large size and supports a fishery of some magnitude in other parts of the Indian coast. The results presented here are based on the data collected on the landing of the species at Mangalore and Malpe during 1988/'89 - 1993-'9

Effect of triple drug antiretroviral therapy on CD4+ count in pregnant women with HIV and prevention of parent to child transmission

Background: India has moved from single drug Antiretroviral Therapy (ART) in 2002 to triple drug ART in 2013 to prevent parent to child transmission of HIV. The aim of the study was to know the effects of triple drug ART on maternal CD4+ count and prevention of HIV transmission to baby along with its adherence, side effects and pregnancy outcome.Methods: A prospective study wsas done in Safdarjung Hospital, New Delhi on 40 HIV positive pregnant women who received single dose combination of triple drug ART. CD4+ count, LFT and KFT were done before beginning of ART and repeated after 6 months of ART. The infants received nevirapine prophylaxis and HIV status was determined by DBS PCR at 6 weeks.Results: The median CD4+ count was 317 and 397 pre and post ART for 6 months respectively (p value<0.001. Low birth weight (LBW) was seen in 43.59% which was statistically significant but confounded as 76.4% of these babies were preterm. 23.08% of babies had an APGAR of < 7 at 1 minute, out of which 77.7% were preterm. Nine out of 39 infants (one had abortion) needed NICU admission. Only one baby (2.56%) was HIV positive who died at 4 months of age due to pneumonia. There was no defaulter and no statistically significant changes in LFT and KFT after 6 months of ART.Conclusions: Triple drug ART offers greater convenience improves fetomaternal outcome and minimize the risk of HIV transmission from mother to child