1,727 research outputs found
A Parallax Distance to the Microquasar GRS 1915+105 and a Revised Estimate of its Black Hole Mass
Using the Very Long Baseline Array, we have measured a trigonometric parallax
for the micro quasar GRS 1915+105, which contains a black hole and a K-giant
companion. This yields a direct distance estimate of 8.6 (+2.0,-1.6) kpc and a
revised estimate for the mass of the black hole of 12.4 (+2.0,-1.8) Msun. GRS
1915+105 is at about the same distance as some HII 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 +/- 0.03 mas/y and
-6.24 +/- 0.05 mas/y toward the east and north, respectively, which corresponds
to a modest peculiar speed of 22 +/-24 km/s 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 60 +/- 5 deg and a variable flow speed
between 0.65c and 0.81c, which possibly indicates deceleration of the jet at
distances from the black hole >2000 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.Comment: 20 pages; 2 tables; 6 figure
Kinematics of Black Hole X-ray Binary GRS 1915+105
The space velocity of a stellar black hole encodes the history of its
formation and evolution. Here we measure the 3-dimensional motion of the
microquasar GRS 1915+105, using a decade of astrometry with the NRAO Very Long
Baseline Array, together with the published radial velocity. The velocity in
the Galactic Plane deviates from circular rotation by 53-80 +_ 8 km/s, where
the range covers any specific distance from 6-12 kpc. Perpendicular to the
plane, the velocity is only 10 +_ 4 km/s. The peculiar velocity is minimized at
a distance 9-10 kpc, and is then nearly in the radial direction towards the
Galactic Center. We discuss mechanisms for the origin of the peculiar velocity,
and conclude that it is most likely a consequence of Galactic velocity
diffusion on this old binary, rather than the result of a supernova kick during
the formation of the 14 Mo black hole. Finally, a brief comparison is made with
4 other BH binaries whose kinematics are well determined.Comment: 16 pages, 4 figures. ApJ accepte
Economic impact of dissemination of management strategies for sucking insect pests on transgenic cotton in Punjab, India
Integrated pest management (IPM) strategies for the management of sucking insect pests were disseminated in 36 villages of three districts of Punjab during 2008 to 2010. Adoption of IPM strategies led to reduction in the population of jassid, whitefly and mealybug in IPM villages. Mean population of jassid was 0.62 and 1.60 nymphs per three leaves, whitefly 1.11 and 2.53 adults per three leaves and mealybug 0.53 and 1.03 per 2.5 cm of central shoot in IPM and non-IPM villages, respectively. Mean population of spiders, chrysoperla, coccinellids and predatory bugs was 0.65, 0.13, 0.15 and 0.04 in IPM villages and 0.29, 0.09, 0.06 and 0.00 per plant in non-IPM villages, respectively. IPM strategies resulted in the 47.69 and 50.56 per cent reduction in number of spray and cost of spray in IPM villages over non-IPM villages. The average cost of cultivation was Rs. 21324 ha−1 in IPM villages, as compared to non-IPM villages (Rs. 23774.67 ha−1). Average seed cotton yield in IPM villages was 2333 kg ha−1 in comparison to non-IPM villages (1959.67 kg ha−1) and average net return in IPM villages was Rs. 57194 ha−1, which was Rs. 15709 more than non-IPM villages
Pomegranate Peel Extract Decreases Plaque Necrosis and Advanced Atherosclerosis Progression in Apoe(-/-) Mice
Atherosclerosis is a chronic lipid-driven inflammatory condition of the arteries and is a leading cause of stroke, myocardial infarction, and other peripheral arterial diseases. Plant products rich in polyphenols such as pomegranate juice and peel extract are known to have beneficial effects in suppressing atherogenesis. However, the mechanism of action and its effect on advanced atherosclerosis progression which results in adverse clinical outcomes are not well understood. Herein, we use a standardized hydroethanolic extract of Punica granatum (pomegranate) peel in the Apoe ( -/- ) a murine model of advanced atherosclerosis. It was observed that the pomegranate peel extract fed mice have decreased plaque necrosis and elevated lesional collagen content which was associated with a favorable metabolic profile including lowering of blood glucose, cholesterol, and triglyceride. The decrease in plaque necrosis was linked with increased lesional macrophage efferocytosis efficiency which was associated with enhanced expression of the efferocytosis receptor Mertk. Using in vitro studies, we show that pomegranate peel extract blocks the shedding of Mertk and preserves macrophage efferocytosis efficiency. These data identify a novel mechanism by which pomegranate peel extract promotes the resolution of inflammation in atherosclerosis
Guest Editorial to the Special Letters Issue on Emerging Technologies in Multiparameter Biomedical Optical Imaging and Image Analysis
The past two decades have witnessed revolutionary advances
in biomedical imaging modalities capable of providing
biological and physiological information from the cellular
scale to the organ level. Recent advances have also been
focused on cost-effective, noninvasive, portable, and molecularimaging
technologies for imaging at microscopic, mesoscopic,
and macroscopic levels. These technologies have significant
potential to advance biomedical research and clinical practice.
They can also provide a better understanding and monitoring
of physiological and functional disorders, which could lead to
mainstream diagnostic technologies of the future
On the role of magnetic reconnection in jet/accretion disk systems
The most accepted model for jet production is based on the
magneto-centrifugal acceleration out off an accretion disk that surrounds the
central source (Blandford & Payne, 1982). This scenario, however, does not
explain, e.g., the quasi-periodic ejection phenomena often observed in
different astrophysical jet classes. de Gouveia Dal Pino & Lazarian (2005)
(hereafter GDPL) have proposed that the large scale superluminal ejections
observed in microquasars during radio flare events could be produced by violent
magnetic reconnection (MR) episodes. Here, we extend this model to other
accretion disk systems, namely: active galactic nuclei (AGNs) and young stellar
objects (YSOs), and also discuss its role on jet heating and particle
acceleration.Comment: To be published in the IAU Highlights of Astronomy, Volume 15, XXVII
IAU General Assembly, August 2009, Ian F. Corbett et al., eds., 201
Switching Language Modes: Complementary Brain Patterns for Formulaic and Propositional Language
© John J. Sidtis et al. 2018. Language has been modeled as a rule governed behavior for generating an unlimited number of novel utterances using phonological, syntactic, and lexical processes. This view of language as essentially propositional is expanding as a contributory role of formulaic expressions (e.g., you know, have a nice day, how are you?) is increasingly recognized. The basic features of the functional anatomy of this language system have been described by studies of brain damage: left lateralization for propositional language and greater right lateralization and basal ganglia involvement for formulaic expressions. Positron emission tomography (PET) studies of cerebral blood flow (CBF) have established a cortical-subcortical pattern of brain activity predictive of syllable rate during phonological/lexical repetition. The same analytic approach was applied to analyzing brain images obtained during spontaneous monologues. Sixteen normal, right-handed, native English speakers underwent PET scanning during several language tasks. Speech rate for the repetition of phonological/lexical items was predicted by increased CBF in the left inferior frontal region and decreased CBF in the head of the right caudate nucleus, replicating previous results. A complementary cortical-subcortical pattern (CBF increased in the right inferior frontal region and decreased in the left caudate) was predictive of the use of speech formulas during monologue speech. The use of propositional language during the monologues was associated with strong left lateralization (increased CBF at the left inferior frontal region and decreased CBF at the right inferior frontal region). Normal communication involves the integration of two language modes, formulaic and novel, that have different neural substrates
The first accurate parallax distance to a black hole
Using astrometric VLBI observations, we have determined the parallax of the
black hole X-ray binary V404 Cyg to be 0.418 +/- 0.024 milliarcseconds,
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 less than 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.Comment: Accepted for publication in ApJ Letters. 6 pages, 2 figure
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