25,108 research outputs found

    A double peaked pulse profile observed in GX 1+4

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    The hard X-ray pulsar GX 1+4 was observed several times in the last few years with a pair of balloon-borne Xenon filled Multi-cell Proportional Counters (XMPC). In a balloon flight made on 22 March 1995, the source was detected in a bright state, the average observed source count rate being 8.0±0.2/s8.0\pm0.2/s per detector. X-ray pulsations with a period of 121.9±0.1121.9\pm0.1 s were detected in the source with a broad double peak pulse feature. When observed in December 1993 with the same instrument, the pulse profile of GX 1+4 showed a single peak. This change in the pulse profile to a double pulse structure in about 15 months indicates either activation of the opposite pole of the neutron star if the magnetic field is asymmetric or possibly a change in the beam pattern, from a pencil beam to a fan beam. Assuming a fan beam configuration, the pulse profile is used to find the inclinations of the magnetic axis and the viewing axis with the spin axis. The derived angles support the GINGA observations of a dip in the pulse profile which was resolved to have a local maximum in one of the observations and was explained with resonance scattering of cyclotron line energy photons by the accretion column (Makishima et al., \markcite{maki1988}, Dotani et al., \markcite{dotani1989}.). Compared to our previous observation of the same source with the same telescope (Rao et al., \markcite{rao1994}) a period change rate of 0.72±0.40s/yr0.72 \pm 0.40 s/yr is obtained which is the lowest rate of change of period for this source since its discovery. Average pulse fraction in the hard X-ray range is low (30%), consistent with its anti correlation with luminosity as reported by us earlier (Rao et al., \markcite{rao1994}) and the observed spectrum is very hard (power law photon index 1.67±0.121.67\pm0.12).Comment: 10 pages, to appear in A&

    Estimation and Determinants of Chronic Poverty in India : An Alternative Approach

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    The paper conceptualizes chronic poverty by using the spaces of income and nutrition and estimates its incidence among states and social groups. It also aims to improve our understanding of the determinant of chronic poverty by considering economic, demographic and social factors. It attempts to answer the following questions : How important a determinant of chronic poverty is household income? What factors inhibit escape from chronic poverty? How different are the other poor from chronic poor? The analysis uses the unit level NSS and NFHS data.Chrinic Poverty, India

    Different types of X-ray bursts from GRS 1915+105 and their origin

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    We report the X-ray observations of the Galactic X-ray transient source GRS 1915+105 with the PPCs of the Indian X-ray Astronomy Experiment(IXAE) onboard the Indian satellite IRS-P3 during 1997 June - August, which have revealed the presence of four types of intense X-ray bursts. All the observed bursts have a slow exponential rise, a sharp linear decay, and they can broadly be put in two classes: irregular and quasi-regular bursts in one class, and regular bursts in another class. The regular bursts are found to have two distinct time scales and they persist over extended durations. There is a strong correlation between the preceding quiescent time and the burst duration for the quasi-regular and irregular bursts. No such correlation is found for the regular bursts. The ratio of average flux during the burst time to the average flux during the quiescent phase is high and variable for the quasi- regular and irregular bursts while it is low and constant for the regular bursts. We suggest that the peculiar bursts that we have seen are charact- eristic of the change of state of the source. The source can switch back and forth between the low-hard state and the high-soft state near critical accretion rates in a very short time scale. A test of the model is presented using the publicly available 13-60 keV RXTE/PCA data for irregular and regular bursts concurrent with our observations.Comment: 13 pages, 12 figures, Accepted in APJ, emulateapj style use

    Estimation and determinants of chronic poverty in India: An Alternative approach

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    The paper conceptualizes chronic poverty by using the spaces of income and nutrition and estimates its incidence among states and social groups. It also aims to improve our understanding of the determinant of chronic poverty by considering economic, demographic and social factors. It attempts to answer the following questions: How important a determinant of chronic poverty is household income? What factors inhibit escape from chronic poverty? How different are the other poor from chronic poor? The analysis uses the unit level NSS and NFHS data.

    Estimation in a growth study with irregular measurement times

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    Between 1982 and 1988 a growth study was carried out at the Division of Pediatric Oncology of the University Hospital of Groningen. A special feature of the project was that sample sizes are small and that ages at entry may be very different. In addition the intended design was not fully complied with. This paper highlights some aspects of the statistical analysis which is based on (1) reference scores, (2) statistical procedures allowing for an irregular pattern of measurement times caused by missing data and shifted measurement times

    Snow cover, snowmelt and runoff in the Himalayan River basins

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    Not withstanding the seasonal vagaries of both rainfall amount and snowcover extent, the Himalayan rivers retain their basic perennial character. However, it is the component of snowmelt yield that accounts for some 60 to 70 percent of the total annual flow volumes from Hamilayan watersheds. On this large hydropotential predominantly depends the temporal performance of hydropower generation and major irrigation projects. The large scale effects of Himalayan snowcover on the hydrologic responses of a few selected catchments in western Himalayas was studied. The antecedent effects of snowcover area on long and short term meltwater yields can best be analyzed by developing appropriate hydrologic models forecasting the pattern of snowmelt as a function of variations in snowcover area. It is hoped that these models would be of practical value in the management of water resources. The predictability of meltwater for the entire snowmelt season was studied, as was the concurrent flow variation in adjacent watersheds, and their hydrologic significance. And the applicability of the Snowmelt-Runoff Model for real time forecast of daily discharges during the major part of the snowmelt season is examined

    The Analysis of Essential Factors Responsible for Loss of Labour Productivity in Building Construction Projects in India

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    The purpose of this paper is to find the essential factors influencing the loss of labour productivity (LP) in construction in India and substantiate these factors with naturalistic observation method in a building construction project. From the past studies, factors influencing the LP are specifically selected for the survey and statistically analyzed to form into defined group of factors. The influence of these factors is then correlated to the field level LP. For this, a case study is conducted using TMS technique to inspect factors influencing LP in an ongoing multi storied residential building construction site in Telangana State, India. The LP factors identified by survey analysis are quantitatively validated with the field study. It is noted that work characteristics, organizational characteristics, assured and safety work and workers management were responsible for 15% loss of LP in the field. Of these, major loss of about 11% is shown by work characteristics factors such as material delay and tools delay. This method can be utilized by construction personnel to measure the loss of LP with the data available from survey methods and also assists the construction personnel in making timely decisions towards the improvement of LP for various activities on the construction project sites

    Developments in the production of soderberg paste for electrodes in ferro alloy furnaces

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    Using raw petroleum coke as raw-material, NML has devel-oped a dense carbon aggregate as a substitute for gas calcined anthracite. This dense carbon aggregate has been used for making soderberg paste, the properties of which have been studied and compared with a Norwegian and two indigenous pastes. The suitability of this material has been tested on a commercial scale in ferro alloy and pig iron furnaces. Attempts also have been made to produce dense carbon aggregate by partial replacement of petroleum coke with low ash coal and the study of its properties have been described in this paper
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