302 research outputs found

    Chandra & HST Imaging of the Quasars PKS B0106+013 & 3C345: Inverse Compton X-rays and Magnetized Jets

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    We present results from deep (70 ks) Chandra ACIS observations and Hubble Space Telescope ACS F475W observations of two highly optically polarized quasars belonging to the MOJAVE blazar sample, viz., PKS B0106+013 and 1641+399 (3C345). These observations reveal X-ray and optical emission from the jets in both sources. X-ray emission is detected from the entire length of the 0106+013 radio jet, which shows clear bends or wiggles - the X-ray emission is brightest at the first prominent kpc jet bend. A picture of a helical kpc jet with the first kpc-scale bend representing a jet segment moving close(r) to our line of sight, and getting Doppler boosted at both radio and X-ray frequencies, is consistent with these observations. The X-ray emission from the jet end however peaks at about 0.4" (~3.4 kpc) upstream of the radio hot spot. Optical emission is detected both at the X-ray jet termination peak and at the radio hot spot. The X-ray jet termination peak is found upstream of the radio hot spot by around 0.2" (~1.3 kpc) in the short projected jet of 3C345. HST optical emission is seen in an arc-like structure coincident with the bright radio hot spot, which we propose is a sharp (apparent) jet bend instead of a terminal point, that crosses our line of sight and consequently has a higher Doppler beaming factor. A weak radio hot spot is indeed observed less than 1" downstream of the bright radio hot spot, but has no optical or X-ray counterpart. By making use of the pc-scale radio and the kpc-scale radio/X-ray data, we derive constraints on the jet Lorentz factors (Gamma_jet) and inclination angles (theta): for a constant jet speed from pc- to kpc-scales, we obtain a Gamma_jet of ~70 for 0106+013, and ~40 for 3C345. On relaxing this assumption, we derive a Gamma_jet of ~2.5 for both the sources. Upper limits on theta of ~13 degrees are obtained for the two quasars. (ABRIDGED)Comment: 46 pages, 11 figures, Accepted for publication in Ap

    Probing the Active Massive Black Hole Candidate in the Center of NGC 404 with VLBI

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    Recently Nyland et al. (2012) argued that the radio emission observed in the center of the dwarf galaxy NGC 404 originates in a low-luminosity active galactic nucleus (LLAGN) powered by a massive black hole (M<106M\sim<10^6 M_{\odot}). High-resolution radio detections of MBHs are rare. Here we present sensitive, contemporaneous Chandra X-ray, and very long baseline interferometry (VLBI) radio observations with the European VLBI Network (EVN). The source is detected in the X-rays, and shows no long-term variability. If the hard X-ray source is powered by accretion, the apparent low accretion efficiency would be consistent with a black hole in the hard state. Hard state black holes are known to show radio emission compact on the milliarcsecond scales. However, the central region of NGC 404 is resolved out on 10 milliarcsecond (0.15-1.5 pc) scales. Our VLBI non-detection of a compact, partially self-absorbed radio core in NGC 404 implies that either the black hole mass is smaller than 32+5×1053^{+5}_{-2}\times10^5 M_{\odot}, or the source does not follow the fundamental plane of black hole activity relation. An alternative explanation is that the central black hole is not in the hard state. The radio emission observed on arcsecond (tens of pc) scales may originate in nuclear star formation or extended emission due to AGN activity, although the latter would not be typical considering the structural properties of low-ionization nuclear emission-line region galaxies (LINERs) with confirmed nuclear activity.Comment: Accepted for publication in the Astrophysical Journal. 7 pages, 2 figures, 1 tabl

    Chandra Discovery of 10 New X-Ray Jets Associated With FR II Radio Core-Selected AGNs in the MOJAVE Sample

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    The Chandra X-ray observatory has proven to be a vital tool for studying high-energy emission processes in jets associated with Active Galactic Nuclei (AGN).We have compiled a sample of 27 AGN selected from the radio flux-limited MOJAVE (Monitoring of Jets in AGN with VLBA Experiments) sample of highly relativistically beamed jets to look for correlations between X-ray and radio emission on kiloparsec scales. The sample consists of all MOJAVE quasars which have over 100 mJy of extended radio emission at 1.4 GHz and a radio structure of at least 3" in size. Previous Chandra observations have revealed X-ray jets in 11 of 14 members of the sample, and we have carried out new observations of the remaining 13 sources. Of the latter, 10 have Xray jets, bringing the overall detection rate to ~ 78%. Our selection criteria, which is based on highly compact, relativistically beamed jet emission and large extended radio flux, thus provides an effective method of discovering new X-ray jets associated with AGN. The detected X-ray jet morphologies are generally well correlated with the radio emission, except for those displaying sharp bends in the radio band. The X-ray emission mechanism for these powerful FR II (Fanaroff-Riley type II) jets can be interpreted as inverse Compton scattering off of cosmic microwave background (IC/CMB) photons by the electrons in the relativistic jets. We derive viewing angles for the jets, assuming a non-bending, non-decelerating model, by using superluminal parsec scale speeds along with parameters derived from the inverse Compton X-ray model. We use these angles to calculate best fit Doppler and bulk Lorentz factors for the jets, as well as their possible ranges, which leads to extreme values for the bulk Lorentz factor in some cases. When both the non-bending and non-decelerating assumptions are relaxed [abridged]Comment: 38 Pages, 4 Figures, 5 Tables, accepted for publication in Ap

    DEVELOPMENT AND STATISTICAL OPTIMIZATION OF GASTRORETANTIVE FLOATING MICROSPHERES OF PREGABALIN PREPARED BY W/O/O MULTIPLE EMULSION METHOD

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    Objective: The aim of this study is to develop a gastroretentive microsphere of pregabalin using design of experiment (DoE) to decrease dosing frequency and increasing bioavailability. Methods: Pregabalin microsphere was prepared by W/O/O multiple emulsion method using a mixture of ethyl cellulose (EC) and polyvinyl pyrrolidone (PVP) as rate-controlling polymer. Mixed solvent system comprising of dichloromethane (DCM) and acetonitrile (ACN) and light liquid paraffin was chosen as primary and secondary oil phase respectively. Taguchi design was employed for factor screening and Box Behnken design was used for the optimisation of critical process parameters. Results: Taguchi design revealed that polymer: drug, DCM: ACN and PVP: EC is the critical factor for the preparation of microspheres. The optimized formulation was prepared using polymer: drug (4.95:1), DCM: ACN (53.76: 46.24) and PVP: EC (2:5) which showed mean particle size of 203.34±4.82 µm, practical yield of 87.52±2.91 %, encapsulation efficiency of 96.43±3.14 %, floating ability up to 90.42±1.64 % and T60% of 332.81±5.84. Drug release from microsphere followed Higuchi Kinetic model. Conclusion: In a nutshell, microspheres with excellent flowability and great encapsulation efficiency were successfully developed. These can be useful in improving patient compliance by reducing frequent dosing

    The Properties and Gaseous Environments of Powerful Classical Double Radio Galaxies

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    The properties of a sample of 31 very powerful classical double radio galaxies with redshifts between zero and 1.8 are studied. The source velocities, beam powers, ambient gas densities, total lifetimes, and total outflow energies are presented and discussed. The rate of growth of each side of each source were obtained using a spectral aging analysis. The beam power and ambient gas density were obtained by applying the strong shock jump conditions to the ends of each side of the source. The total outflow lifetime was obtained by applying the power-law relationship between the beam power and the total source lifetime derived elsewhere for sources of this type, and the total outflow energy was obtained by combining the beam power and the total source lifetime. Composite profiles were constructed by combining results obtained from each side of each source. The composite profiles indicate that the ambient gas density falls with distance from the central engine. The source velocities, beam powers, total lifetimes, and total energies seem to be independent of radio source size. This is consistent with the standard model in which each source grows at a roughly constant rate during which time the central engine puts out a roughly constant beam power. The fact that the total source lifetimes and energies are independent of radio source size indicates that the sources are being sampled at random times during their lifetimes.Comment: 7 pages, 5 figures, to appear in "Extragalactic Jets: Theory and Observation from Radio to Gamma Ray", eds. T. A. Rector and D. S. De Young, ASP conference series, Replaced version has minor textual correction

    Cord blood angiogenic profile in normotensive pregnancies

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    Human placenta undergoes both angiogenesis and vasculogenesis during fetal development. An imbalance in proangiogenic [placental growth factor (PlGF) and vascular endothelial growth factor] and antiangiogenic factors [soluble fms like tyrosine kinase-1 (sFlt-1), soluble endoglin (sEng)] has been reported to have a role in pathophysiology of preeclampsia. Hence the present study was designed to analyze heme oxygenase-1 and endoglin levels in maternal and cord blood of normotensive women. The study comprised of twenty five normotensive pregnant women immediately after delivery Study samples were drawn (maternal venous blood and umbilical cord blood) and heme oxygenase-1 (HO-1) and endoglin levels were analyzed by competitive enzyme linked immunosorbent assay. Heme oxygenase-1 levels were elevated in maternal blood as compared to cord blood of normotensive pregnant women. Also, serum blood endoglin levels were higher in maternal blood compared to cord blood of normotensive pregnant women. These findings indicate that there is angiogenic balance during normotensive pregnancy and dysbalance might occur during pathological pregnancy. These markers of angiogenic balance may serve as diagnostic marker and may help in explaining future risk of cardiovascular disease in these women.Keywords: Vasculogenesis; Proangiogenic and antiangiogenic factors; Pregnanc

    Relationship between gestational age and endoglin levels in maternal and cord blood

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    Background: Poor placentation at early gestational age is an important predisposing condition for the development of preeclampsia. The present study was designed to study the relationship of gestational age with endoglin levels in maternal and cord blood of normal and pre-eclamptic women.Methods: The present study was conducted in fifty pregnant women that were grouped as: group 1 (control, n=25) comprising of normotensive women immediately after delivery, group 2 (study group, n=25) comprising of age -and sex- matched pre-eclamptic women. Study samples were drawn (maternal venous blood and umbilical cord blood). Endoglin was analyzed by competitive enzyme linked immunosorbent assay.Results: Maternal serum endoglin levels were decreased in group II as compared to group I. Maternal endoglin showed a positive correlation with gestational age in both normotensive and preeclamptic women. Cord blood endoglin showed negative correlation with gestational age in both normotensive women and preeclamptics. A significant positive correlation was found between maternal and cord blood endoglin levels with birth weight in preeclamptic mothers. Pre-eclamptics with birth weight less than 2.5 kg had lower maternal blood endoglin levels as compared to controls.Conclusions: These finding suggest that endoglin levels may responsible for the pathogenesis of PE and/or IUGR
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