1,324 research outputs found
Mapping the Kinematics of the Narrow-Line Region in the Seyfert Galaxy NGC 4151
Using The Hubble Space Telescope's Space Telescope Imaging Spectrograph HST's
STIS, observations of the OIII emission from the narrow-line region (NLR) of
NGC 4151 were obtained and radial velocities determined. Five orbits of HST
time were used to obtain spectra at five parallel slit configurations, at a
position angle of 58 degrees, with spatial resolution 0.2 arcseconds across and
0.1 arcseconds along each slit. A spectral resolving power of ~ 9,000 with the
G430M grating gave velocity measurements accurate to ~ 34 km/s. A kinematic
model was generated to match the radial velocities, for comparison to previous
kinematic models of biconical radial outflow developed for low-dispersion
spectra at two slit positions. The new high-resolution spectra permit the
measurement of accurate velocity dispersions for each radial-velocity
component. The full-width at half-maximum (FWHM) reaches a maximum of 1000 km/s
near the nucleus, and generally decreases with increasing distance to about 100
km/s in the extended narrow-line region (ENLR), starting at about 6 arcseconds
from the nucleus. In addition to the bright emission knots, which generally fit
our model, there are faint high velocity clouds which do not fit the biconical
outflow pattern of our kinematic model. These faint clouds occur at the
turnover points of the outflowing bright clouds. We suggest possible scenarios
that could explain these rogue clouds: (1) backflow resulting from shocks and
(2) outflow outside of the bicones, although the latter does not explain how
the knots are ionized and accelerated. A comparison of our observations with a
high-resolution radio map shows that there is no evidence that the kinematics
of the NLR clouds are affected by the radio lobes that comprise the inner jet.Comment: 30 pages, 15 figures (some color), accepted for publication in the
Astronomical Journal. Downloadable versions of the paper with high resolution
figures/images are available here:
http://www.chara.gsu.edu/~crenshaw/NGC4151_kinematics.pdf <--PDF Version
http://www.chara.gsu.edu/~crenshaw/NGC4151_kinematics.ps <--PS Versio
Magellanic Cloud X-ray Sources: III. Completion of a ROSAT Survey
This paper concludes a series of three papers presenting ROSAT
High-Resolution Imager (HRI) observations of unidentified Einstein and
serendipitous ROSAT X-ray sources in the direction of the Magellanic Clouds.
Accurate positions and fluxes have been measured for these sources. Optical
photometry and spectroscopy were obtained to search for identifications in
order to determine the physical nature of these sources. The present paper
includes new data for 24 objects; identifications are given or confirmed for 30
sources. For six sources optical finding charts showing the X-ray positions are
provided. The results from this program are summarized, showing the populations
of luminous X-ray sources in the Magellanic Clouds are quite different from
those in the Galaxy.Comment: 28 pages, 2 figures; to appear in Astronomical Journa
Microscopic theory of quadrupolar ordering in TmTe
We have calculated the crystal electric field of TmTe (T>T_Q) and have
obtained that the ground state of a Tm 4f hole is the doublet in
agreement with Mossbauer experiments. We study the quadrupole interactions
arising from quantum transitions of 4f holes of Tm. An effective attraction is
found at the L point of the Brillouin zone, . Assuming that the
quadrupolar condensation involves a single arm of we show that
there are two variants for quadrupole ordering which are described by the space
groups C2/c and C2/m. The Landau free energy is derived in mean-field theory.
The phase transition is of second order. The corresponding quadrupole order
parameters are combinations of and components. The obtained
domain structure is in agreement with observations from neutron diffraction
studies for TmTe. Calculated lattice distortions are found to be different for
the two variants of quadrupole ordering. We suggest to measure lattice
displacements in order to discriminate between those two structures.Comment: 10 pages, 2 figures, 5 tables; accepted by PR
On the nature of the FBS blue stellar objects and the completeness of the Bright Quasar Survey. II
In Paper I (Mickaelian et al. 1999), we compared the surface density of QSOs
in the Bright Quasar Survey (BQS) and in the First Byurakan Survey (FBS) and
concluded that the completeness of the BQS is of the order of 70% rather than
30-50% as suggested by several authors. A number of new observations recently
became available, allowing a re-evaluation of this completeness. We now obtain
a surface density of QSOs brighter than B = 16.16 in a subarea of the FBS
covering ~2250 deg^2, equal to 0.012 deg^-2 (26 QSOs), implying a completeness
of 53+/-10%.Comment: LaTeX 2e, 11 pages, 3 tables and 3 figures (included in text). To
appear in Astrophysics. Uses a modified aaspp4.sty (my_aaspp4.sty), included
in packag
Characterizing eve: Analysing cybercrime actors in a large underground forum
Underground forums contain many thousands of active users, but the vast majority will be involved, at most, in minor levels of deviance. The number who engage in serious criminal activity is small. That being said, underground forums have played a significant role in several recent high-profile cybercrime activities. In this work we apply data science approaches to understand criminal pathways and characterize key actors related to illegal activity in one of the largest and longest- running underground forums. We combine the results of a logistic regression model with k-means clustering and social network analysis, verifying the findings using topic analysis. We identify variables relating to forum activity that predict the likelihood a user will become an actor of interest to law enforcement, and would therefore benefit the most from intervention. This work provides the first step towards identifying ways to deter the involvement of young people away from a career in cybercrime.Alan Turing Institut
Disgust sensitivity is not associated with health in a rural Bangladeshi sample.
Disgust can be considered a psychological arm of the immune system that acts to prevent exposure to infectious agents. High disgust sensitivity is associated with greater behavioral avoidance of disease vectors and thus may reduce infection risk. A cross-sectional survey in rural Bangladesh provided no strong support for this hypothesis. In many species, the expression of pathogen- and predator-avoidance mechanisms is contingent on early life exposure to predators and pathogens. Using childhood health data collected in the 1990s, we examined if adults with more infectious diseases in childhood showed greater adult disgust sensitivity: no support for this association was found. Explanations for these null finding and possible directions for future research are discussed
The Resolved Narrow Line Region in NGC4151
We present slitless spectra of the Narrow Line Region (NLR) in NGC4151 from
the Space Telescope Imaging Spectrograph (STIS) on HST, and investigate the
kinematics and physical conditions of the emission line clouds in this region.
Using medium resolution (~0.5 Angstrom) slitless spectra at two roll angles and
narrow band undispersed images, we have mapped the NLR velocity field from 1.2
kpc to within 13 pc (H_o=75 km/s/Mpc) of the nucleus. The inner biconical cloud
distribution exhibits recessional velocities relative to the nucleus to the NE
and approaching velocities to the SW of the nucleus. We find evidence for at
least two kinematic components in the NLR. One kinematic component is
characterized by Low Velocities and Low Velocity Dispersions (LVLVD clouds: |v|
< 400 km/s, and Delta_v < 130 km/s). This population extends through the NLR
and their observed kinematics may be gravitationally associated with the host
galaxy. Another component is characterized by High Velocities and High Velocity
Dispersions (HVHVD clouds: 400 130 km/s). This
set of clouds is located within 1.1 arcsec (~70pc) of the nucleus and has
radial velocities which are too high to be gravitational in origin, but show no
strong correlation between velocity or velocity dispersion and the position of
the radio knots. Outflow scenarios will be discussed as the driving mechanism
for these HVHVD clouds.Comment: 38 pages, 14 figures, accepted by ApJ. For higher resolution images
see http://www.pha.jhu.edu/~kaiser
Orbital-Controlled Superconductivity in f-Electron Systems
We propose a concept of superconductivity controlled by orbital degree of
freedom taking CeMIn5 (M= Co, Rh, and Ir) as typical examples. A microscopic
multiorbital model for CeMIn5 is analyzed by fluctuation exchange
approximation. Even though the Fermi-surface structure is unchanged, the ground
state is found to change significantly among paramagnetic, antiferromagnetic,
and d-wave superconducting phases, depending on the dominant orbital component
in the band near the Fermi energy. We show that our picture naturally explains
the different low-temperature properties of CeMIn5 by carefully analyzing the
crystalline electric field states.Comment: 5 pages, 4 figure
Safety and efficacy of parsaclisib in combination with obinutuzumab and bendamustine in patients with relapsed or refractory follicular lymphoma (CITADEL-102): A phase 1 study
Parsaclisib is a potent and highly selective PI3KÎŽ inhibitor that has shown clinical benefit with monotherapy in a phase 2 study in relapsed or refractory (R/R) follicular lymphoma (FL). CITADEL-102 (NCT03039114), a phase 1, multicenter study, assessed the efficacy of parsaclisib in combination with obinutuzumab and bendamustine in patients with R/R FL. Patients were â„18 years of age with histologically confirmed and documented CD20-positive FL, and R/R to previous rituximab-containing treatment regimens. Part one (safety run-in) determined the maximum tolerated dose of parsaclisib in combination with standard dosage regimens of obinutuzumab and bendamustine. Part two (dose expansion) was an open-label, single-group design evaluating safety, tolerability (primary endpoint), and efficacy (secondary endpoint) of parsaclisib combination therapy. Twenty-six patients were enrolled in CITADEL-102 and all patients received parsaclisib 20 mg once daily for 8 weeks, followed by 20 mg once weekly thereafter, in combination with obinutuzumab and bendamustine. One patient in safety run-in experienced a dose-limiting toxicity of grade 4 QT interval prolongation that was considered related to parsaclisib. Eight patients (30.8%) discontinued treatment due to treatment-emergent adverse events (TEAEs) of colitis (2 [7.7%]), alanine aminotransferase and aspartate aminotransferase increase (both in one patient [3.8%]), neutropenia, thrombocytopenia, QT prolongation, tonsil cancer, and maculopapular rash (each 1 [3.8%]). The most common reported TEAEs were pyrexia (53.8%), neutropenia (50.0%), and diarrhea (46.2%). Twenty-three patients (88.5%) experienced grade 3 or 4 TEAEs; the most common were neutropenia (34.6%), febrile neutropenia (23.1%), and thrombocytopenia (19.2%). Seventeen patients (65.4%) had a complete response and 3 patients (11.5%) had a partial response, for an objective response rate of 76.9%. Overall, results from CITADEL-102 suggest that the combination of parsaclisib with obinutuzumab and bendamustine did not result in unexpected safety events, with little evidence of synergistic toxicity, and demonstrated preliminary efficacy in patients with R/R FL who progressed following prior rituximab-containing regimens
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