We use multiepoch quasar spectroscopy to determine how accurately single-epoch spectroscopy can locate quasars in emission-line parameter space in order to inform investigations where time-resolved ...spectroscopy is not available. We explore the improvements in emission-line characterization that result from using nonparametric information from many lines as opposed to a small number of parameters for a single line, utilizing reconstructions based on an independent component analysis applied to the data from the Sloan Digital Sky Survey Reverberation Mapping project. We find that most of the quasars are well described by just two components, while more components signal a quasar likely to yield a successful reverberation mapping analysis. In single-epoch spectroscopy the apparent variability of equivalent width is exaggerated because it is dependent on the continuum. Multiepoch spectroscopy reveals that single-epoch results do not significantly change where quasars are located in C iv parameter space and do not have a significant impact on investigations of the global Baldwin effect. Quasars with emission-line properties indicative of higher L/LEdd are less variable, consistent with models with enhanced accretion disk density. Narrow absorption features at the systemic redshift may be indicative of orientation (including radio-quiet quasars) and may appear in as much as 20% of the quasar sample. Future work applying these techniques to lower-luminosity quasars will be important for understanding the nature of accretion disk winds.
Abstract
We examine the UV/X-ray properties of 1378 quasars in order to link empirical correlations to theoretical models of the physical mechanisms dominating quasars as a function of mass and ...accretion rate. The clarity of these correlations is improved when (1) using C
iv
broad emission line equivalent width (EQW) and blueshift (relative to systemic) values calculated from high signal-to-noise ratio reconstructions of optical/UV spectra and (2) removing quasars expected to be absorbed based on their UV/X-ray spectral slopes. In addition to using the traditional C
iv
parameter space measures of C
iv
EQW and blueshift, we define a “C
iv
∥ distance” along a best-fit polynomial curve that incorporates information from both C
iv
parameters. We find that the C
iv
∥ distance is linearly correlated with both the optical-to-X-ray slope,
α
ox
, and broad-line He
ii
EQW, which are known spectral energy distribution indicators, but does not require X-ray or high spectral resolution UV observations to compute. The C
iv
∥ distance may be a better indicator of the mass-weighted accretion rate, parameterized by
L
/
L
Edd
, than the C
iv
EQW or blueshift alone, as those relationships are known to break down at the extrema. Conversely, there is only a weak correlation with the X-ray energy index (Γ), an alternate
L
/
L
Edd
indicator. We find no X-ray or optical trends in the direction perpendicular to the C
iv
distance that could be used to reveal differences in accretion disk, wind, or corona structure that could be widening the C
iv
EQW–blueshift distribution. A different parameter (such as metallicity) not traced by these data must come into play.
ABSTRACT
The census of obscured quasar populations is incomplete and remains a major unsolved problem, especially at higher redshifts, where we expect a greater density of galaxy formation and quasar ...activity. We present Gemini GNIRS near-infrared spectroscopy of 24 luminous obscured quasar candidates from the Sloan Digital Sky Survey’s Stripe 82 region. The targets were photometrically selected using a WISE/W4 selection technique that is optimized to identify IR-bright and heavily reddened/optically obscured targets at z > 1. We detect emission lines of Hα, Hβ, and/or O iii in 23 sources allowing us to measure spectroscopic redshifts in the range 1 < z < 3 with bolometric luminosities spanning L = 1046.3–1047.3 erg s−1. We observe broad 103–104 km s−1 Balmer emissions with large Hα/Hβ ratios, and we directly observe a heavily reddened rest-frame optical continuum in several sources, suggesting high extinction (AV ∼ 7–20 mag). Our observations demonstrate that such optical/infrared photometric selection successfully recovers high-redshift obscured quasars. The successful identification of previously undetected red, obscured high-redshift quasar candidates suggests that there are more obscured quasars yet to be discovered.
Abstract
We present 10 seasons of Sloan Digital Sky Survey
r
-band monitoring observations and five seasons of
H
-band observations of the two-image system FBQ J0951+2635 from the Kaj Strand ...Astrometric Reflector at the United States Naval Observatory, Flagstaff Station. We supplement our light curves with six seasons of monitoring data from the literature to yield a 10 + 6 season combined data set, which we analyzed with our Monte Carlo microlensing analysis routine to generate constraints on the structure of this system’s continuum emission source and the properties of the lens galaxy. Complementing our optical light curves with the five-season near-infrared light curves, we ran a joint Monte Carlo analysis to measure the size of the continuum emission region at both wavelengths, yielding log(
r
1/2
cm
−1
) =
16.24
−
0.36
+
0.33
in the
r
band and
17.04
−
0.30
+
0.26
in the
H
band at rest wavelengths of 2744 and 7254 Å, respectively, correcting for an assumed inclination angle of 60°. Modeling the accretion disk temperature profile as a power law
T
(
r
) ∝
r
−
β
, we successfully constrain the slope for FBQ J0951+2635 to
β
=
0.50
−
0.18
+
0.50
, shallower than, but nominally consistent with, the predictions of standard thin-disk theory,
β
= 0.75.
Abstract
We discuss a probe of the contribution of wind-related shocks to the radio emission in otherwise radio-quiet quasars. Given (1) the nonlinear correlation between UV and X-ray luminosity in ...quasars, (2) that such a correlation leads to higher likelihood of radiation-line-driven winds in more luminous quasars, and (3) that luminous quasars are more abundant at high redshift, deep radio observations of high-redshift quasars are needed to probe potential contributions from accretion disk winds. We target a sample of 50
z
≃ 1.65 color-selected quasars that span the range of expected accretion disk wind properties as traced by broad C
iv
emission. 3 GHz observations with the Very Large Array to an rms of ≈10
μ
Jy beam
−1
probe to star formation rates of ∼400
M
⊙
yr
−1
, leading to 22 detections. Supplementing these pointed observations are survey data of 388 sources from the LOFAR Two-meter Sky Survey Data Release 1 that reach comparable depth (for a typical radio spectral index), where 123 sources are detected. These combined observations reveal a radio detection fraction that is a nonlinear function of C
iv
emission-line properties and suggest that the data may require multiple origins of radio emission in radio-quiet quasars. We find evidence for radio emission from weak jets or coronae in radio-quiet quasars with low Eddington ratios, with either (or both) star formation and accretion disk winds playing an important role in optically luminous quasars and correlated with increasing Eddington ratio. Additional pointed radio observations are needed to fully establish the nature of radio emission in radio-quiet quasars.
To assess the use of tongue base palpation during cancer screening exams by Oral Healthcare Providers (OHPs) and explore attitudes about (1) the usefulness of oral cancer screening (OCS) in detecting ...early, asymptomatic lesions and (2) routine OCS of the general population.
Survey study.
Private and hospital-based clinical practices of OHPs located in Massachusetts and Connecticut, United States.
An anonymous, online 9-item survey assessing beliefs and practice patterns about cancer screening exams was distributed to OHPs with practices in Massachusetts and Connecticut from August 2020 to June 2021. Data were analyzed using chi-square tests and Pearson correlations. Statistically significant levels were established at P < .050.
One hundred seventy-one responses were analyzed (response rate 17 %). Tongue base palpation was performed as part of a routine cancer screening exam by 55 % of otolaryngologists, 34 % of dentists and 29 % of OMFS (P = .030). Providers who palpated the tongue base were also more likely to use palpation as an exam technique in the tonsils (r = 0.52 95 % CI 0.40–0.62; P < .001) among other intra-and extra-oral anatomical subsites. Almost all dentists (92 %) and OMFS (98 %) but only 58 % of otolaryngologists considered OCS useful for detection of early, asymptomatic malignant lesions in the oral cavity (P < .001).
While tongue base palpation can detect oropharyngeal cancers in a pre-symptomatic stage, it is underutilized during routine cancer screening exams. Considering the rising incidence of oropharyngeal cancer, tongue base palpation should be established as a routine part of cancer screening by OHPs.
In this collection, local experts use personal narratives and
empirical data to explore the history of Mexican American and
Puerto Rican education in the Chicago Public Schools (CPS) system.
The ...essays focus on three themes: the historical context of
segregated and inferior schooling for Latina/o/x students; the
changing purposes and meanings of education for Latina/o/x students
from the 1950s through today; and Latina/o/x resistance to
educational reforms grounded in neoliberalism. Contributors look at
stories of student strength and resistance, the oppressive systems
forced on Mexican American women, the criminalization of Puerto
Ricans fighting for liberatory education, and other topics of
educational significance. As they show, many harmful past practices
remain the norm--or have become worse. Yet Latina/o/x communities
and students persistently engage in transformative practices
shaping new approaches to education that promise to reverberate not
only in the city but nationwide.
Insightful and enlightening, Latina/o/x Education in
Chicago brings to light the ongoing struggle for educational
equity in the Chicago Public Schools.
Mexico is the top producer of silver and is on the eighth place from producing gold in the world. For instance, the hydrometallurgical extraction process produces wastewater (mining tailing) ...characterized by being composed with varying concentrations of cyanide and heavy metals. The purpose of this research was to study the biodegradation of cyanide contained in mining tailings by means of a bacterial consortium isolated from a tailings dam. For this purpose, three types of Eckendfelder reactors were used, one with suspended biomass (BS) and two moving bed biofilter reactors, one with biomass immobilized on Kaldnes (BK) supports, and the other on polyurethane cubes (BCP). Three experimental stages were worked; in each of them, the concentrations of total cyanide were varied. In the first one, it was 26 ± 2 mg·L
−1
; in the second one 40 ± 4 mg·L
−1
; and the third one 55 ± 4 mg·L
−1
. During the whole operation, the pH and temperature were maintained at 9.5 units and 25 °C. After 141 days of operation, biodegradation of the total cyanide contained in the mining tailings was 69% (17 mg·L
−1
) in the BS reactor, while in the BK reactor, it was 93% (3.9 mg·L
−1
) and in the BCP reactor 95% (2.5 mg·L
−1
). The predominant families in each of the reactors, as well as their respective relative abundances, were for the BS and for the BK of
Cyclobacteriaceae
(20.65% and 24.64%) and
Rhizobiaceae
(18.48% and 14.01%) and
Halomonadaceae
(46.97%) and
Hyphomonadaceae
(24.94%) in the BCP.
A Novel Test of Quasar Orientation Richards, Gordon T.; Plotkin, Richard M.; Hewett, Paul C. ...
Astrophysical journal. Letters,
06/2021, Letnik:
914, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Abstract
The orientation of the disk of material accreting onto supermassive black holes that power quasars is one of most important quantities that are needed to understand quasars—both individually ...and in the ensemble average. We present a hypothesis for determining comparatively edge-on orientation in a subset of quasars (both radio loud and radio quiet). If confirmed, this orientation indicator could be applicable to individual quasars without reference to radio or X-ray data and could identify some 10%–20% of quasars as being more edge-on than average, based only on moderate resolution and signal-to-noise spectroscopy covering the C
iv
λ
1549 Å emission feature. We present a test of said hypothesis using X-ray observations and identify additional data that are needed to confirm this hypothesis and calibrate the metric.
Gpn1 associates with Gpn3, and both are required for RNA polymerase II nuclear targeting. Global studies have identified by mass spectrometry that human Gpn3 is ubiquitinated on lysines 189 and 216. ...Our goals here were to determine the type, physiological importance, and regulation of Gpn3 ubiquitination. After inhibiting the proteasome with MG132, Gpn3‐Flag was polyubiquitinated on K216, but not K189, in HEK293T cells. Gpn3‐Flag exhibited nucleo‐cytoplasmic shuttling, but polyubiquitination and proteasomal degradation of Gpn3‐Flag occurred only in the cell nucleus. Polyubiquitination‐deficient Gpn3‐Flag K216R displayed a longer half‐life than Gpn3‐Flag in two cell lines. Interestingly, Gpn1‐EYFP inhibited Gpn3‐Flag polyubiquitination in a dose‐dependent manner. In conclusion, Gpn1‐inhibitable, nuclear polyubiquitination on lysine 216 regulates the half‐life of Gpn3 by tagging it for proteasomal degradation.
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