302 research outputs found
Chandra & HST Imaging of the Quasars PKS B0106+013 & 3C345: Inverse Compton X-rays and Magnetized Jets
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
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). 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 M, 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
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
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
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
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
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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