21 research outputs found

    Normalization: A Preprocessing Stage

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    As we know that the normalization is a pre-processing stage of any type problem statement. Especially normalization takes important role in the field of soft computing, cloud computing etc. for manipulation of data like scale down or scale up the range of data before it becomes used for further stage. There are so many normalization techniques are there namely Min-Max normalization, Z-score normalization and Decimal scaling normalization. So by referring these normalization techniques we are going to propose one new normalization technique namely, Integer Scaling Normalization. And we are going to show our proposed normalization technique using various data sets.Comment: 4 pages, 3 figures, 3 table

    Further evidence for intra-night optical variability of radio-quiet quasars

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    Although well established for BL Lac objects and radio-loud quasars, the occurrence of intra-night optical variability (INOV) in radio-quiet quasars is still debated, primarily since only a handful of INOV events with good statistical significance, albeit small amplitude, have been reported so far. This has motivated us to continue intra-night optical monitoring of bona-fide radio-quiet quasars (RQQs). Here we present the results for a sample of 11 RQQs monitored by us on 19 nights. On 5 of these nights a given RQQ was monitored simultaneously from two well separated observatories. In all, two clear cases and two probable case of INOV were detected. From these data, we estimate an INOV duty cycle of \sim8% for RQQs which would increase to 19% if the `probable variable' cases are also included. Such comparatively small INOV duty cycles for RQQs, together with the small INOV amplitudes (\sim1%), are in accord with the previously deduced characteristics of this phenomenon.Comment: 15 Pages, 4 Tables, 24 Figures; Accepted in BAS

    Rapid optical variability of TeV blazars

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    In this first systematic attempt to characterise the intranight optical variability (INOV) of TeV detected blazars, we have monitored a well defined set of 9 TeV blazars on total 26 nights during 2004-2010. In this R (or V)-band monitoring programme only one blazar was monitored per night for a minimum duration of 4 hours. Using the CCD, an INOV detection threshold of ~ 1-2 % was achieved in the densely sampled DLCs. We have further expanded the sample by including another 13 TeV blazars from literature. This enlarged sample of 22 TeV blazars, monitored on a total of 116 nights (including 55 nights newly reported here), has enabled us to arrive at the first estimate of the INOV duty cycle of TeV detected blazars. Applying the C-test, the INOV DC is found to be 59 %, which decreases to 47 % if only INOV fractional amplitudes above 3 % are considered. These observations also permit, for the first time, a comparison of the INOV characteristics of the two major subclasses of TeV detected BL Lacs, namely LBLs and HBLs, for which we find the INOV DCs to be ~ 63 % and ~ 38 %, respectively. This demonstrates that the INOV differential between LBLs and HBLs persists even when only their TeV detected subsets are considered. Despite dense sampling, the intranight light curves of the 22 TeV blazars have not revealed even a single feature on time scale substantially shorter than 1 hour, even though the inner jets of TeV blazars are believed to have exceptionally large bulk Lorentz factors (and correspondingly stronger time compression). An intriguing feature, clearly detected in the light curve of the HBL J1555+1111, is a 4 per cent `dip' on a 1 hour timescale. This unique feature could have arisen from absorption in a dusty gas cloud, occulting a superluminally moving optical knot in the parsec scale jet of this relatively luminous BL Lacs object.Comment: 39 pages, 3 figures, accepted for publication in MNRA

    Intra-night optical variability of core dominated radio quasars: the role of optical polarization

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    Context. Rapid variations in optical flux are seen in many quasars and all blazars. The amount of variability in different classes of active galactic nuclei has been studied extensively but many questions remain unanswered. Aims. We present the results of a long-term programme to investigate the intra-night optical variability (INOV) of powerful flat spectrum radio core-dominated quasars (CDQs), with a focus on probing the relationship of INOV to the degree of optical polarization. Methods. We observed a sample of 16 bright CDQs showing strong broad optical emission lines and consisting of both high and low optical polarization quasars (HPCDQs and LPCDQs). In this first systematic study of its kind, we employed the 104-cm Sampurnanand telescope, the 201-cm Himalayan Chandra telescope and the 200-cm IUCAA-Girawali Observatory telescope, to carry out R-band monitoring on a total of 47 nights. Using the CCD as an N-star photometer to densely monitor each quasar for a minimum duration of about 4 h per night, INOV exceeding ~1–2 per cent could be reliably detected. Combining these INOV data with those taken from the literature, after ensuring conformity with the basic selection criteria we adopted for the 16 CDQs monitored by us, we were able to increase the sample size to 21 CDQs (12 LPCDQs and 9 HPCDQs) monitored on a total of 73 nights. Results. As the existence of a prominent flat-spectrum radio core signifies that strong relativistic beaming is present in all these CDQs, the definitions of the two sets differ primarily in fractional optical polarization, with the LPCDQs showing a very low median Pop ≃ 0.4 per cent. Our study yields an INOV duty cycle (DC) of ~28 per cent for the LPCDQs and ~68 percent for HPCDQs. If only strong INOV with fractional amplitude above 3 per cent is considered, the corresponding DCs are ~7 per cent and ~40 per cent, respectively. Conclusions. From this strong contrast between the two classes of luminous, relativistically beamed quasars, it is apparent that relativistic beaming is normally not a sufficient condition for strong INOV and a high optical polarization is the other necessary condition. Moreover, the correlation is found to persist for many years after the polarization measurements were made. Some possible implications of this result are pointed out, particularly in the context of the recently detected rapid γ-ray variability of blazars

    Optical variability of radio-intermediate quasars

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    We report the results of our intensive intranight optical monitoring of 8 `radio-intermediate quasars' (RIQs) having flat or inverted radio spectra. The monitoring was carried out in {\it R-} band on 25 nights during 2005-09. An intranight optical variability (INOV) detection threshold of \sim 1--2% was achieved for the densely sampled differential light curves (DLCs). These observations amount to a large increase over those reported hitherto for this rare and sparsely studied class of quasars which can, however, play an important role in understanding the link between the dominant varieties of powerful AGN, namely the radio-quiet quasars (RQQs), radio-loud quasars (RLQs) and blazars. Despite the probable presence of relativistically boosted nuclear jets, clear evidence for INOV in our extensive observations was detected only on one night. These results demonstrate that as a class, RIQs are much less extreme in nuclear activity compared to blazars. The availability in the literature of INOV data for another 2 RIQs conforming to our selection criteria allowed us to enlarge the sample to 10 RIQs (monitored on a total of 42 nights for a minimum duration of 4\sim 4 hours per night). The absence of large amplitude INOV (ψ>3(\psi > 3%) persists in this enlarged sample. This extensive database has enabled us to arrive at the first estimate for the INOV Duty Cycle (DC) of RIQs. The DC is found to be small (\sim 9%). The corresponding value is known to be 60\sim 60% for BL Lacs and 15\approx 15% for RLQs and RQQs. On longer-term, the RIQs are found to be fairly variable with typical amplitudes of \approx 0.1-mag. The light curves of these RIQs are briefly discussed in the context of a theoretical framework proposed earlier for linking this rare kind of quasars to the much better studied dominant classes of quasars.Comment: 35 pages, 2 figures, 3 tables, accepted for publication in MNRA

    Unusual optical quiescence of the classical BL Lac object PKS 0735+178 on intranight time-scale

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    We present the result of our extensive intranight optical monitoring of the well-known low-energy peaked BL Lac (LBL) object PKS 0735+178. This long-term follow-up consists of R -band monitoring for a minimum duration of ∼4 hours, on 17 nights spanning 11 years (1998–2008). Using the CCD as an N-star photometer, a detection limit of around 1 per cent was attained for the intranight optical variability (INOV). Remarkably, an INOV amplitude of ≥3 per cent on hour-like time-scale was not observed on any of the 17 nights, even though the likelihood of a typical LBL showing such INOV levels in a single session of >4 hours duration is known to be high (∼50 per cent) . Our observations have thus established a peculiar long-term INOV quiescence of this radio-selected BL Lac object. Moreover, the access to unpublished optical monitoring data of similarly high sensitivity, acquired in another programme, has allowed us to confirm the same anomalous INOV quiescence of this LBL all the way back to 1989, the epoch of its historically largest radio outburst. Here, we present observational evidence revealing the very unusual INOV behaviour of this classical BL Lac object and discuss this briefly in the context of its other known exceptional properties.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/74920/1/j.1365-2966.2009.15385.x.pd

    <i style="">In silico</i> 3-D structure prediction of H1N1 2009 neuraminidase and comparative analysis of coding statistics of mutated genes

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    148-155The enzyme neuraminidase (NA), coded by H1N1 virus, catalyses the removal of terminal sialic acid from viral and cellular glycoconjugates. It cleaves the terminal sialic acid on the glycosylated NA during virus budding to facilitate virus release. The outbreak of Swine flu is suspected to be caused due to H274Y mutation in the neuraminidase enzyme of H1N1 2009 strain. The present study involves 3-D structure modeling of mutated neuraminidase of the strain A/Poland/274/2009 (H1N1) by MODELLER9v7 and comparative analysis of coding statistics among NA gene of 3 mutated H1N1 strains with GenBank accession numbers GU112751, GU371269 and CY053923. The analysis of 3-D model revealed that NAs have a common fold characterised by β-pleated sheet flanked either side by helices. The amino terminal end of the molecule is occupied by β-α-β motif and carboxy terminal end by β-hairpin motif. The molecule is characterised by 24 strands and 3 helices. The α1 helix is the longest among the three helices. The comparative analysis of coding statistics indicates that the statistical features f1, f5, f6 and f7 have the most discriminating power for the individual recognition of the mutated neuraminidase genes of H1N1 2009

    Comparative intra-night optical variability of high and low polarization quasars with dominant radio cores

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    We present the initial results of a programme to investigate the dependence of intra-night optical variability (INOV) of powerful AGN, on the degree of optical polarization. For the first systematic study of this kind, we employed 104-cm Sampurnanand telescope (ST) and 201-cm Himalayan Chandra telescope (HCT) to carry out R-band monitoring of a sample of 8 optically bright radio core dominated quasars showing low optical polarization (P &lt; 3 %) (LPCDQ). Selected from literature in an biased manner, having flat or inverted spectrum at giga hertz frequencies, these LPCDQs were monitored on a total of 23 nights, by monitoring only one of them per night (average duration of monitoring being 5.6 hr per night). Using the CCD as an N-star photometer, a INOV detection threshold of approx 1-2% could be achieved for these densely sampled differential light curves (DLCs). The microvariations were clearly detected on many nights, with peak to peak INOV amplitude ranging from 1.2% to 5.3% (median 2%). While the presence of dominant radio core at centimetre wavelenghts in all these quasars signifies relativistic beaming, they differ strongly from BL Lac objects in showing a very low optical polarization (median P_op0.4 %). From our observations we determine the duty cycle (DC) of 43pm10%, for INOV for these LPCDQs. The corresponding value for BL Lac objects is known to be around 60%. Thus, using these measurements we evaluate the comaparative roles of optical polarization and relativistic beaming on the phenomenon of intra-night optical variability

    Evaluation of p53 protein expression in Barrett esophagus

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    Background: Loss of heterozygosity of p53 along with aneuploidy is deemed to be the early molecular steps in Barrett metaplasia-dysplasia-adenocarcinoma sequence. Objective biomarkers need to be used along with microscopy for risk stratification to predict the progression of Barrett esophagus (BE) to carcinoma. Aim: This study aims to study p53 protein expression in dysplasia and correlate the same with morphology in BE. Materials and Methods: A time-bound study was conducted from January 2011 to June 2015. All esophageal biopsies showing histological evidence of columnar epithelium with the presence of goblet cells were included. The cases which showed dysplasia were graded on hematoxylin and eosin stain. Evaluation of p53 immunohistochemistry staining was done on all the cases of BE. Dysplasia was correlated with the expression of p53 using Chi-square value (χ2) and Fischer's exact test wherever appropriate. P < 0.05 was considered to be statistically significant. Results: Of 829 esophageal biopsies received, 119 were endoscopically suspected to be BE, of which 85 cases were confirmed on microscopy. In our study, there were 75 cases negative for dysplasia (88.2%), 8 with low-grade dysplasia (LGD) (9.4%), and two with high-grade dysplasia (HGD) (2.4%). Three cases of BE had associated adenocarcinoma. Immunostaining with p53 done on all the 85 cases showed positive staining in all cases with LGD, one with HGD and two with adenocarcinoma. In the present study, immunostaining with p53 showed 90% sensitivity, 89.3% specificity, positive predictive value of 52.9%, and negative predictive value of 98.5%. Conclusion: The technical simplicity, easy availability, and comparatively lower cost enhance the role of p53 as a biomarker in risk stratification for patients with BE
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