612 research outputs found

    Secondary periodicities of microbursts of TeV gamma rays from the Crab pulsar

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    Observations were made during the past several years on the Crab pulsar using the Ooty atmospheric Cerenkov array with the aim of detecting possible emission of ultra high energy gamma rays by the pulsar. During the course of these observations, it was found that the Crab pulsar emits TeV gamma rays in bursts of short duration. The microbursts of TeV gamma rays from the Crab pulsar, which were seen in the data of at least three years, also reveal interesting secondary periodicities. It was noticed at first that some bursts could be connected with the others that occurred during the same night or during the next two nights with integral number of cycles of periods 43 + or - 1 minute. Ten possible periods in the vicinity of 43 minutes were determined for all the combinations of bursts for each year. The best values of periods thus obtained were different from year to year. But when, instead of the real time, the number of Crab cycles elapsed between the bursts was used as the unit of time, two values of burst periods - 77460 and 77770 Crab cycles - were found to be significant in the data of at least two years. A Monte Carlo simulation using 1500 trial periods chosen randomly within + or - 5 minutes of the original burst period did not reveal any value of the period as significant

    Forecasting Stock Time-Series using Data Approximation and Pattern Sequence Similarity

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    Time series analysis is the process of building a model using statistical techniques to represent characteristics of time series data. Processing and forecasting huge time series data is a challenging task. This paper presents Approximation and Prediction of Stock Time-series data (APST), which is a two step approach to predict the direction of change of stock price indices. First, performs data approximation by using the technique called Multilevel Segment Mean (MSM). In second phase, prediction is performed for the approximated data using Euclidian distance and Nearest-Neighbour technique. The computational cost of data approximation is O(n ni) and computational cost of prediction task is O(m |NN|). Thus, the accuracy and the time required for prediction in the proposed method is comparatively efficient than the existing Label Based Forecasting (LBF) method [1].Comment: 11 page

    Observations on TeV gamma rays from Geminga and PSR 0950+08

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    The Geminga (2 CG 195+04) which exhibits a periodicity with a period of 59 to 60 s in its emission of X-rays, GeV gamma rays and TeV gamma rays was studied. During the winter of 1984 to 1985, this object was observed to see if it emits TeV gamma rays with a periodicity approx 60 s. The observations were carried out at two different sites separated by 11 Km with the Ooty Atmospheric Cerenkov Array split into two parts. Data were collected during clear moonless nights for a total duration of 15.3 hours spread over 2 months. Since the first time derivative of period is believed to be large and uncertain. The total data are subdivided into segments of duration not more than 3 days each to steer clear of the effects of P in the phase analysis. If TeV gamma ray signals are seen in each of these segments, it is possible to derive P from observed data

    Geo-Metallurgical Studies of Rampura Agucha Deposit

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    Rampura Agucha deposit which is the 5 th largest deposit in the world in terms of the reserves and 3'd largest in terms of metal production, is also one of the most complex deposit in the world in terms of its textural characteri-stics, due to its highly deformed nature. The paper details the results of Geo-metallurgical studies for identification of domains within the deposit with similar textural characteristics and their correlation with actual plant performance. As recovery performance of the valuable minerals directly impacts the profitability, the plant metallurgist would be very much interested in improvement of recovery performance of lead / zinc and the inputs of process mineralogy for understanding metallurgical process are very important and the insights provided by process mineralogy in understanding and improving the recovery processes are described

    Pulsed emission of TeV gamma rays from Vela pulsar

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    The Ooty atmospheric Cerenkov array, consisting of 10 parabolic mirrors of 0.9 m diameter and 8 of 1.5 m diameter, was used for observations on the Vela pulsar to see if it emits gamma rays in the TeV energy range. During the winter of 1984-85, the array was split into two parts: (1) consisting wholly of the smaller mirrors, and (2) wholly of the bigger mirrors. The two arrays were operated at two different sites to distinguish a marginally significant genuine pulsar signal from spurious signals produced trivially by chance fluctuations in the background rates. All the mirrors were pointed at the celestial object to track it for durations of the order of 1 to 6 hours during clear moonless nights. The event time data is analyzed to detect a possible pulsed emission of TeV gamma rays using the contemporaneous pulsar elements on the basis of their radio observations on the Vela pulsar. Results from the analyses of observations made during the winters of 1982-83 and 1984-85 on steady pulsed emission and on possible transient emission is presented

    HUMAN SECRETORY PHOSPHOLIPASE A2 (sPLA2) INHIBITION BY AQUEOUS EXTRACT OF MACROTYLOMA UNIFLORUM (SEED) AS AN ANTI-INFLAMMATORY ACTIVITY

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    Objective: Macrotyloma uniflorum (Horse gram) is an important legume widely consumed in the tropical south Asian countries including India. The present investigation is the elucidation of anti-inflammatory activity of M. uniflorum as it has several medicinal properties. The M. uniflorum was evaluated for inhibition of human secretory phospholipase A2 (sPLA2) as a function of anti-inflammatory activity.Methods: The total phenols, antioxidant (DPPH scavenging), Anti-lipid peroxidation, PLA2 inhibition and lipoxygenase (5 & 15-LOX) inhibition activity of aqueous extracts of M. uniflorum coat and pulp were assayed by in vitro method. The aqueous extract of M. uniflorum seed coat was subjected to inhibit PLA2 enzymes from human inflammatory fluids (Human Synovial Fluid and Human Pleural Fluid) and snake venoms (Naja naja and Vipera russllii) using [14]C labeled E. coli by in vivo method. A further effect of substrate and calcium concentration on inhibition of VRV-PLA2 in presence and absence of M. uniflorum coat extract were assayed.Results: Aqueous coat extract of M. uniflorum shows higher phenolics and biological activity and inhibited all sPLA2 enzymes in concentration dependent manner. The IC50 values are found to be in the range of 11.42-20.88μg and IC50 values for 5-LOX and 15-LOX is 25.92μg and 32.47μg respectively. The extract effectively neutralized indirect hemolytic activity and showed similar potency in neutralizing the in vivo sPLA2 induced mouse paw edema.Conclusion: These findings suggest that, the active compound/s in extracts of M. uniflorum individually or synergistically responsible for observed sPLA2 inhibition.Â

    Microburst of TeV gamma rays from the Crab pulsar

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    Data on Crab pulsar from atmospheric Cerenkov array at Ooty have shown emission of TeV gamma rays in the form of microbursts. These are a series of events which are unusually closely spaced in time with time separations of less than 1.5 milliseconds. The phasogram of events in the bursts when analyzed with the Crab pulsar period shows significant peaks. Data further show that the signal is at the same absolute phase as the radio peak. Monte Carlo calculations show that the probability of peaks being due to chance is very small

    Ligand Docking Methods to Recognize Allosteric Inhibitors for G-Protein-Coupled Receptors.

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    G-protein-coupled receptors (GPCRs) are membrane proteins which play an important role in many cellular processes and are excellent drug targets. Despite the existence of several US Food and Drug Administration (FDA)-approved GPCR-targeting drugs, there is a continuing challenge of side effects owing to the nonspecific nature of drug binding. We have investigated the diversity of the ligand binding site for this class of proteins against their cognate ligands using computational docking, even if their structures are known already in the ligand-complexed form. The cognate ligand of some of these receptors dock at allosteric binding site with better score than the binding at the conservative site. Interestingly, amino acid residues at such allosteric binding site are not conserved across GPCR subfamilies. Such a computational approach can assist in the prediction of specific allosteric binders for GPCRs

    IN VITRO HEPATOPROTECTIVE ACTIVITY OF EXTRACTS OF VIBURNUM PUNCTATUM BUCH-HAM EX D.DON AGAINST CARBON TETRACHLORIDE INDUCED TOXICITY

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    Objective: The study was aimed to evaluate of in vitro hepatoprotective activity of Chloroform and Methanol extracts of Viburnum punctatum (200 and 400 μg/ml) against carbon tetrachloride induced toxicity. Methods: The screening of hepatoprotective activity was based on the protection of human liver derived Chang liver cells against CCl4 induced damage determined by MTT assay [(3-(4,5 dimethylthiazole-2yl)-2,5-diphenyl tetrazolium bromide assay] using Silymarin as standard. Results: The chang liver cells were treated with different concentrations of chloroform and methanol extracts of Viburnum punctatum, showed a dose dependent increase in percentage viability and the results were highly significant (P<0.001, when compared with CCl4 induced group). The percentage viability ranged between 62 to 84% at 200-400µg/ml concentrations. The methanolic extract exhibited more hepatoprotective activity when compared to chloroform extract. Conclusion: The results clearly demonstrate that Viburnum punctatum possess promising hepatoprotective effects and hence suggests to isolate and identify the active principle involved in the hepatoprotective activity
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