599 research outputs found
The Black Hole to Bulge Mass Relation in Active Galactic Nuclei
The masses of the central black holes in Active Galactic Nuclei (AGNs) can be
estimated using the broad emission-lines as a probe of the virial mass. Using
reverberation mapping to determine the size of the Broad Line Region (BLR) and
the width of the variable component of the line profile H line it is
possible to find quite accurate virial mass estimates for AGNs with adequate
data. Compiling a sample of AGNs with reliable central masses and bulge
magnitudes we find an average black-hole-to-bulge mass ratio of 0.0003, a
factor of 20 less than the value found for normal galaxies and for bright
quasars. This lower ratio is more consistent with the back hole mass density
predicted from quasar light, and is similar to the central black hole/bulge
mass ratio in our Galaxy. We argue that the black hole/bulge mass ratio
actually has a significantly larger range than indicated by mssive black holes
detected in normal galaxies (using stellar dynamics) and in bright quasars,
which may be biased towards large black holes. We derive a scenario of black
hole growth that explains the observed distribution.Comment: 12 pages LaTeX, including 2 revised figures, revised table. Revised
version to be published in the Astrophysical Journal (Letters) Ap.J.Lett. 51
DEVELOPMENT AND VALIDATION OF RP-HPLC METHOD FOR DETERMINATION OF HYDROCHLOROTHIAZIDE, OLMESARTAN MEDOXOMIL AND THEIR RELATED SUBSTANCES IN COMBINED TABLET DOSAGE FORM
Objective: Development of RP-HPLC method for determination of Hydrochlorothiazide (HCTZ), Olmesartan medoxomil (OLM) and their related substances in combined tablet dosage form and validation of the developed method.
Methods: Gradient mobile phase system was used for estimation of drug contents and their related substances. Mobile phase A contained the mixture of Acetonitrile and 15 mM Phosphate buffer (pH adjusted to 3.4 with orthophosphoric acid) in the ratio of 20:80. Mobile phase B contained the same mixture in the ratio of 80:20. Chromatographic separation was carried out at the mobile phase flow rate of 0.8 mL/min using C18 Phenomenax inplace of Enable (250 × 4.6 mm) 5 μm column and detection was made at 254 nm.
Results: The linearity of developed method was tested in the range of 62.5-187.5 μg/mL for Hydrochlorothiazide, 100-300 μg/mL for Olmesartan medoxomil, 1-1.8 μg/mL for Hydrochlorothiazide. The % recovery was found to be 99.88-100.67 % (HCTZ), 99.14-99.91 % (OLM), 99.11-100.71% (HCTZ-IMP) and 98.13-100.83% (OLM-IMP). The assay of marketed formulation was found to be 99.78% (HCTZ) and 99.26% (OLM).
Conclusion: A simple, precise and accurate RP-HPLC method was developed for determination of Hydrochlorothiazide, Olmesartan medoxomil and their related substances
Spins of the supermassive black hole in M87: new constraints from TeV observations
The rapid TeV ray variability detected in the well-known nearby
radio galaxy M87 implies an extremely compact emission region (5-10
Schwarzschild radii) near the horizon of the supermassive black hole in the
galactic center. TeV photons are affected by dilution due to interaction with
the radiation field of the advection-dominated accretion flow (ADAF) around the
black hole, and can thus be used to probe the innermost regions around the
black hole. We calculate the optical depth of the ADAF radiation field to the
TeV photons and find it strongly depends on the spin of the black hole. We find
that transparent radii of 10 TeV photons are of and
for the maximally rotating and non-rotating black holes, respectively. With the
observations, the calculated transparent radii strongly suggest the black hole
is spinning fast in the galaxy. TeV photons could be used as a powerful
diagnostic for estimating black hole spins in galaxies in the future.Comment: 4 pages, 4 figures. to appear in ApJ
Priority setting for collaborative health systems research in India: a method and the way forward
A comprehensive and collaborative knowledge translation and decision-making approach can help reduce the longstanding barriers to using research in policy and practice. Regular interaction between researchers and decision-makers increases the likelihood of using research knowledge. This interaction continuing over the entire research cycle is critical for developing research directions and potential use of the research outputs that benefit the health system. The India Health Systems Collaborative and ACCESS Health International have conducted a rigorous exercise to arrive at the priority research topics. A consensus-based method customised to the existing need was created, adapting from the Child Health and Nutrition Research Initiative (CHNRI) method for research priority setting. In this method, conducting literature reviews, key informant interviews and survey-based stakeholder consultations are critical steps for identifying policy-relevant research topics that demand utmost attention in the Indian setting. This article documents the processes followed to develop a preliminary list of core research priorities requiring urgent attention to facilitate policy development. Additionally, the article is about the essential and immediate next steps and the critical actions taken to undertake collaborative research on the identified research topics. The special issue of the Journal for Health Management dedicated to strengthening the Indian health system sets the foundation for promoting collaborative research, its dissemination for broader use by researchers and ensuing policy dialogues
Young stars and non-stellar emission in the aligned radio galaxy 3C 256
We present ground-based images of the z=1.824 radio galaxy 3C 256 in the
standard BVRIJHK filters and an interference filter centered at 8800A, a Hubble
Space Telescope image in a filter dominated by Ly-alpha emission (F336W), and
spectra covering rest-frame wavelengths from Ly-alpha to [O III] 5007. Together
with published polarimetry observations, we use these to decompose the overall
spectral energy distribution into nebular continuum emission, scattered quasar
light, and stellar emission. The nebular continuum and scattered light together
comprise half (one third) of the V-band (K-band) light within a 4-arcsec
aperture, and are responsible for the strong alignment between the
optical/near-infrared light and the radio emission. The stellar emission is
dominated by a population estimated to be 100-200 Myr old (assuming a Salpeter
IMF), and formed in a short burst with a peak star formation rate of 1-4x10^3
Msun/yr. The total stellar mass is estimated to be no more than 2x10^{11} Msun,
which is far less than other luminous radio galaxies at similar redshifts, and
suggests that 3C 256 will undergo further star formation or mergers.Comment: 35 pages including 10 figures; to appear in Nov 10 Ap
Increased aerobic glycolysis is associated with poor outcome and suppression of apoptosis in human liver cirrhosis and hcc
The black hole mass distribution in early-type galaxies: cusps in HST photometry interpreted through adiabatic black hole growth
The surface brightness profiles of early-type galaxies have central cusps.
Two characteristic profile types are observed with HST: `core' profiles have a
break at a resolved radius and logarithmic cusp slope gamma < 0.3 inside that
radius; `power-law' profiles have no clear break and gamma > 0.3. With few
exceptions, galaxies with M_V
-20.5 have power-law profiles. Both profile types occur in galaxies with -22 <
M_V < -20.5. We show that these results are consistent with the hypothesis
that: (i) all early-type galaxies have black holes (BHs) that grew
adiabatically in homogeneous isothermal cores; and (ii) these `progenitor'
cores followed scaling relations similar to those of the fundamental plane.
The models studied here are the ones first proposed by Young. Models with BH
masses and progenitor cores that obey established scaling relations predict (at
Virgo) that galaxies with M_V < -21.2 have core profiles and galaxies with M_V
> -21.2 have power-law profiles. This reproduces both the sense and the
absolute magnitude of the observed transition. Intrinsic scatter in BH and
galaxy properties can explain why both types of galaxies are observed around
the transition magnitude. The observed bimodality in cusp slopes may be due to
a bimodality in M_bh/L, with rapidly rotating disky galaxies having larger
M_bh/L than slowly rotating boxy galaxies.
Application to individual galaxies with HST photometry yields a roughly
linear correlation between BH mass and V-band galaxy luminosity, log M_bh =
-1.83 + log L (solar units). This agrees with the average relation for nearby
galaxies with kinematically determined BH masses, and also with predictions
from quasar statistics (shortened abstract).Comment: 41 pages, LaTeX, with 11 PostScript figures. Submitted to the
Astronomical Journal. Postscript version also available from
http://sol.stsci.edu/~marel/abstracts/abs_R23.htm
Artificial Intelligence as an Enabler of Quick and Effective Production Repurposing Manufactur-ing: An Exploratory Review and Future Research Propositions
The outbreak of Covid-19 created disruptions in manufacturing operations. One of the most serious negative impacts is the shortage of critical medical supplies. Manufacturing firms faced pressure from governments to use their manufacturing capacity to repurpose their production for meeting the critical demand for necessary products. For this purpose, recent advancements in technology and artificial intelligence (AI) could act as response solutions to conquer the threats linked with repurposing manufacturing (RM). The study’s purpose is to investigate the significance of AI in RM through a systematic literature review (SLR). This study gathered around 453 articles from the SCOPUS database in the selected research field. Structural Topic Modeling (STM) was utilized to generate emerging research themes from the selected documents on AI in RM. In addition, to study the research trends in the field of AI in RM, a bibliometric analysis was undertaken using the R-package. The findings of the study showed that there is a vast scope for research in this area as the yearly global production of articles in this field is limited. However, it is an evolving field and many research collaborations were identified. The study proposes a comprehensive research framework and propositions for future research development
Addressing the interplay between apoptosis and glucose metabolism in liver cirrhosis and hcc
Introduction: Pro-inflammatory signalling in the liver promotes the appearance of a metabolic phenotype that involves the transition from mitochondrial respiration to aerobic glycolysis. It was demonstrated that this metabolic shift occurs during the transition from healthy and early stage of liver injury (NAFLD/NASH, ALD to late stage of disease (i.e. cirrhosis), and further escalates during HCC development.1,2This metabolic signature enables dividing cells to satisfy anabolic and energetic needs for biomass production and to suppress apoptotic signalling, which is consistent with increased compensatory hepatic cell proliferation typical of cirrhotic and HCC livers. However other studies in contrast have suggested that hepatocytes are unable to sustain glycolysis during late stage of chronic liver disease.3 Method: We used unbiased gene expression analyses of microarray datasets to investigate the expression of glycolytic genes in cirrhotic and HCC livers and correlated their expression with patient outcome. Furthermore, by using a combination of in vitro and in vivo analyses we have characterised the abilities of a novel anti-apoptotic gene to regulate aerobic glycolysis in liver cirrhosis and HCC. Results: mRNA profiling showed significantly higher expression of glycolytic transcripts in cirrhotic and HCC livers compared to normal quiescent livers (P < 0.05). Up regulation of Glut1, Hk1, Hk2, G6PI, and PFKLwas seen in HCC livers compared to their adjacent non-tumour tissues (P < 0.001). Notably, expression of enzymes regulating mitochondrial activity (Pdha, Pdk) was unchanged between non-tumour tissues and late stage of HCC. Moreover, up regulation of a novel anti-apoptotic gene positively correlated with increased expression of glycolytic transcripts in a group of cirrhotic patients prospectively classified as poor prognosis based on HCC development, and promotes the aerobic glycolysis of hepatoma cells. Conclusion: In summary, our findings delineate a putative link between aerobic glycolysis and suppression of apoptosis that is an important part of the progression of cirrhosis to HCC. The identification of the mechanism regulating this link may lead to design new therapeutic strategies for human liver disease
QSO's from Galaxy Collisions with Naked Black Holes
In the now well established conventional view (see Rees [1] and references
therein), quasi-stellar objects (QSOs) and related active galactic nuclei (AGN)
phenomena are explained as the result of accretion of plasma onto giant black
holes which are postulated to form via gravitational collapse of the high
density regions in the centers of massive host galaxies. This model is
supported by a wide variety of indirect evidence and seems quite likely to
apply at least to some observed AGN phenomena. However, one surprising set of
new Hubble Space Telescope (HST) observations [2-4] directly challenges the
conventional model, and the well known evolution of the QSO population raises
some additional, though not widely recognized, difficulties. We propose here an
alternative possibility: the Universe contains a substantial independent
population of super-massive black holes, and QSO's are a phenomenon that occurs
due to their collisions with galaxies or gas clouds in the intergalactic medium
(IGM). This hypothesis would naturally explain why the QSO population declines
very rapidly towards low redshift, as well as the new HST data.Comment: plain TeX file, no figures, submitted to Natur
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