Using the Very Long Baseline Array, we have measured a trigonometric parallax for the microquasar GRS 1915+105, which contains a black hole and a K-giant companion. This yields a direct distance ...estimate of 8.6 super(+2.0) sub(-1.6) kpc and a revised estimate for the mass of the black hole of 12.4 super(+2.0) sub(-1.8) M sub(middot in circle). GRS 1915+105 is at about the same distance as some H II regions and water masers associated with high-mass star formation in the Sagittarius spiral arm of the Galaxy. The absolute proper motion of GRS 1915+105 is -3.19 + or - 0.03 mas yr super(-1) and -6.24 + or - 0.05 mas yr super(-1) toward the east and north, respectively, which corresponds to a modest peculiar speed of 22 + or - 24 km s super(-1) at the parallax distance, suggesting that the binary did not receive a large velocity kick when the black hole formed. On one observational epoch, GRS 1915+105 displayed superluminal motion along the direction of its approaching jet. Considering previous observations of jet motions, the jet in GRS 1915+105 can be modeled with a jet inclination to the line of sight of 60degrees + or - 5degrees and a variable flow speed between 0.65c and 0.81c, which possibly indicates deceleration of the jet at distances from the black hole gap2000 AU. Finally, using our measurements of distance and estimates of black hole mass and inclination, we provisionally confirm our earlier result that the black hole is spinning very rapidly.
We report the appearance of a new radio source at a projected offset of 460 pc from the nucleus of Cygnus A. The flux density of the source (which we designate Cygnus A-2) rose from an upper limit of ...<0.5 mJy in 1989 to 4 mJy in 2016 ( = 8.5 GHz), but is currently not varying by more than a few percent per year. The radio luminosity of the source is comparable to the most luminous known supernovae, it is compact in Very Long Baseline Array observations down to a scale of 4 pc, and it is coincident with a near-infrared point source seen in pre-existing adaptive optics and HST observations. The most likely interpretation of this source is that it represents a secondary supermassive black hole in a close orbit around the Cygnus A primary, though an exotic supernova model cannot be ruled out. The gravitational influence of a secondary SMBH at this location may have played an important role in triggering the rapid accretion that has powered the Cygnus A radio jet over the past 107 years.
We present the first direct imaging of what may be the thick torus in the active galactic nucleus (AGN) of the archetype powerful radio galaxy Cygnus A, using the Jansky Very Large Array at 18-48 ...GHz, with a resolution down to 45 mas. Such a torus has long been a key component of AGN models, but direct imaging on the relevant physical scales in sources of extreme (quasar-like) luminosities, remains scarce. An elongated structure, perpendicular to the radio jets and centered on the core, is well resolved, with a full length of 0 48 (528 pc), and a full width of 0 26 (286 pc). The radio emission spectrum is consistent with optically thin free-free emission. We present a toy model of a flaring torus, with a half-opening angle for the poloidal region of 62°. The radio jets are oriented along the poles. The observations require a clumpy gas distribution, with the free-free emission dominated by clumps with densities ≥4000 cm−3.
Using astrometric VLBI observations, we have determined the parallax of the black hole X-ray binary V404 Cyg to be 0.418 +- 0.024 mas, corresponding to a distance of 2.39 +- 0.14 kpc, significantly ...lower than the previously accepted value. This model-independent estimate is the most accurate distance to a Galactic stellar-mass black hole measured to date. With this new distance, we confirm that the source was not super-Eddington during its 1989 outburst. The fitted distance and proper motion imply that the black hole in this system likely formed in a supernova, with the peculiar velocity being consistent with a recoil (Blaauw) kick. The size of the quiescent jets inferred to exist in this system is <1.4 AU at 22 GHz. Astrometric observations of a larger sample of such systems would provide useful insights into the formation and properties of accreting stellar-mass black holes.
Inter simple sequence repeat (ISSR) marker assay was employed to validate the genetic fidelity of Swertia chirayita plantlets multiplied in vitro by axillary multiplication upto forty-two passages. ...Sixteen ISSR primers generated a total of 102 amplicons among the tissue-cultured plants. Forty-eight amplicons were amplified in the outlier (a Swertia species). The outlier (negative control) was employed to rule out the possibility that the invariant fingerprint was due to chance alone and that the ISSR technique employed was not discriminatory enough to detect the off-types. A homogenous amplification profile was observed for all the micropropagated plants. The results confirmed the clonal fidelity of the tissue culture-raised S. chirayita plantlets and corroborated the fact that axillary multiplication is the safest mode for multiplication of true to type plants.
To use (18)F-fluorodeoxyglucose (FDG) and PET to investigate changes in regional metabolism associated with mild cognitive impairment (MCI) in Parkinson disease (PD). Cognitive abnormalities are ...common in PD. However, little is known about the functional abnormalities that underlie the manifestations of MCI in this disorder.
We used FDG PET to measure regional glucose metabolism in patients with PD with multiple-domain MCI (MD-MCI; n = 18), with single-domain MCI (SD-MCI; n = 15), and without MCI (N-MCI; n = 18). These patients were matched for age, education, disease duration, and motor disability. Maps of regional metabolism in the three groups were compared using statistical parametric mapping (SPM). We also computed the expression of a previously validated cognition-related spatial covariance pattern (PDCP) in the patient groups and in an age-matched healthy control cohort (n = 15). PDCP expression was compared across groups using analysis of variance.
SPM revealed decreased prefrontal and parietal metabolism (p < 0.001) in MD-MCI relative to N-MCI, as well as an increase in brainstem/cerebellar metabolism (p < 0.001) in this group. In these regions, SD-MCI occupied an intermediate position between the two other groups. PDCP expression was abnormally elevated in the N-, SD-, and MD-MCI groups (p < 0.05), increasing stepwise with worsening cognitive impairment (p < 0.01).
Early cognitive decline in Parkinson disease as defined by mild cognitive impairment is associated with discrete regional changes and abnormal metabolic network activity. The quantification of these alterations with (18)F-fluorodeoxyglucose PET may allow for the objective assessment of the progression and treatment of this disease manifestation.
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Hepatospecific delivery by ligand based receptor targeting is an established strategy to augment therapy associated with liver diseases and disorders. Previously, we have investigated ...the effect of ligand headgroup on cellular uptake mediated by the asialoglycoprotein receptor by in silico and in vitro approach. In this paper, we report the design of agarose based liposomes for delivery to liver cancer cells and provide a proof of concept of the targeting efficiency against galactose liposomes using an in vivo approach. Sorafenib Tosylate loaded targeting liposomes were developed and optimized using factorial design. Comparative evaluation including cell cytotoxicity, pharmacokinetics and biodistribution and hepatospecific uptake was performed for both the liposomal systems. The formulations possessed a particle size of 150 – 180 nm and a zeta potential of 30 - 60 mV depending on the amount of ligand and drug loading, with more than 90% entrapment efficiency. A two-fold increase in cytotoxicity was observed with agarose-based liposomes as compared to galactose based liposomes. In vivo PK evaluation indicated a reduction in half life of drug when loaded in agarose ligand loaded system, probably due to greater uptake in the liver as evidenced in biodistribution study. Intrahepatic disposition revealed a higher PC/NPC uptake ratio with the targeted systems as compared to conventional liposomes, although the agarose-based system resulted in highest uptake ratio. A biocompatible platform for specific delivery of drugs to hepatocytes was established validating a rational approach to design liver targeting systems.
The neural basis for the transition from preclinical to symptomatic Huntington's disease (HD) is unknown. We used serial positron emission tomography (PET) imaging in preclinical HD gene carriers ...(p-HD) to assess the metabolic changes that occur during this period. Twelve p-HD subjects were followed longitudinally with 11C-raclopride and 18F-fluorodeoxyglucose PET imaging, with scans at baseline, 18 and 44 months. Progressive declines in striatal D2-receptor binding were correlated with concurrent changes in regional metabolism and in the activity of an HD-related metabolic network. We found that striatal D2 binding declined over time (P < 0.005). The activity of a reproducible HD-related metabolic covariance pattern increased between baseline and 18 months (P < 0.003) but declined at 44 months (P < 0.04). These network changes coincided with progressive declines in striatal and thalamic metabolic activity (P < 0.01). Striatal metabolism was abnormally low at all time points (P < 0.005). By contrast, thalamic metabolism was elevated at baseline (P < 0.01), but fell to subnormal levels in the p-HD subjects who developed symptoms. These findings were confirmed with an MRI-based atrophy correction for each individual PET scan. Increases in network expression and thalamic glucose metabolism may be compensatory for early neuronal losses in p-HD. Declines in these measures may herald the onset of symptoms in gene carriers.
We present an intensive radio and X-ray monitoring campaign on the 2009 outburst of the Galactic black hole candidate X-ray binary H1743−322. With the high angular resolution of the Very Long ...Baseline Array, we resolve the jet ejection event and measure the proper motions of the jet ejecta relative to the position of the compact core jets detected at the beginning of the outburst. This allows us to accurately couple the moment when the jet ejection event occurred with X-ray spectral and timing signatures. We find that X-ray timing signatures are the best diagnostic of the jet ejection event in this outburst, which occurred as the X-ray variability began to decrease and the Type C quasi-periodic oscillations disappeared from the X-ray power density spectrum. However, this sequence of events does not appear to be replicated in all black hole X-ray binary outbursts, even within an individual source. In our observations of H1743−322, the ejection was contemporaneous with a quenching of the radio emission, prior to the start of the major radio flare. This contradicts previous assumptions that the onset of the radio flare marks the moment of ejection. The jet speed appears to vary between outbursts, with a possible positive correlation with outburst luminosity. The compact core radio jet reactivated on transition to the hard intermediate state at the end of the outburst, and not when the source reached the low hard spectral state. Comparison with the known near-infrared behaviour of the compact jets suggests a gradual evolution of the compact jet power over a few days near the beginning and end of an outburst.
Cognitive dysfunction is common in Parkinson disease (PD), even early in its clinical course. This disease manifestation has been associated with impaired verbal learning performance as well as ...abnormal expression of a specific PD-related cognitive spatial covariance pattern (PDCP). It is not known, however, how this metabolic network relates to the cognitive response to dopaminergic therapy on the individual patient level.
We assessed treatment-mediated changes in verbal learning and PDCP expression in 17 patients with PD without dementia who underwent cognitive testing and metabolic imaging in the unmedicated and levodopa-treated conditions. We also determined whether analogous changes were present in 12 other patients with PD without dementia who were evaluated before and during the treatment of cognitive symptoms with placebo.
Levodopa-mediated changes in verbal learning correlated with concurrent changes in PDCP expression (r = -0.60, p < 0.01). The subset of patients with meaningful cognitive improvement on levodopa (n = 8) exhibited concurrent reductions in PDCP expression (p < 0.01) with treatment; network modulation was not evident in the remaining subjects. Notably, the levodopa cognitive response correlated with baseline PDCP levels (r = 0.70, p = 0.002). By contrast, placebo did not affect PDCP expression, even in the subjects (n = 7) with improved verbal learning during treatment.
These findings suggest that cognitive dysfunction in PD may respond to treatment depending upon the degree of baseline PDCP expression. Quantification of treatment-mediated network changes can provide objective information concerning the efficacy of new agents directed at the cognitive manifestations of this disease.
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