5,657 research outputs found
Recommended from our members
Macroeconomic Shocks, Job Security and Health: Evidence from the Mining Industry
How do exogenous changes in the macroeconomic environment affect workers’ perceived job security, and consequently, their mental and physical health? To answer this question, we exploit variation in world commodity prices over the period 2001-17 and analyse panel data that includes detailed classifications of mining workers. We find that commodity price increases cause increases in perceived job security, which in turn, significantly and substantively improve the mental health of workers. In contrast, we find no effects on physical health. Our results imply that the estimated welfare costs of recessions are much larger when the effects of job insecurity, and not only unemployment, are considered
Quasar outflow energetics from broad absorption line variability
Quasar outflows have long been recognized as potential contributors to the
co-evolution between supermassive black holes (SMBHs) and their host galaxies.
The role of outflows in AGN feedback processes can be better understood by
placing observational constraints on wind locations and kinetic energies. We
utilize broad absorption line (BAL) variability to investigate the properties
of a sample of 71 BAL quasars with PV broad absorption. The
presence of PV BALs indicates that other BALs like CIV
are saturated, such that variability in those lines favours clouds crossing the
line of sight. We use these constraints with measurements of BAL variability to
estimate outflow locations and energetics. Our data set consists of
multiple-epoch spectra from the Sloan Digital Sky Survey and MDM Observatory.
We detect significant (4) BAL variations from 10 quasars in our sample
over rest frame time-scales between < 0.2-3.8 yr. Our derived distances for the
10 variable outflows are nominally < 1-10 pc from the SMBH using the
transverse-motion scenario, and < 100-1000 pc from the central source using
ionization-change considerations. These distances, in combination with the
estimated high outflow column densities (i.e. > 10
cm), yield outflow kinetic luminosities between ~ 0.001-1 times the
bolometric luminosity of the quasar, indicating that many absorber energies
within our sample are viable for AGN feedback.Comment: 19 pages, 3 figures, 4 tables, 1 supplementary figure, accepted to
MNRA
Identification of individual enzymes in crude extracts by acrylamide gel electrophoresis
Identification of enzymes by acrylamide gel electrophoresi
Constraining FeLoBAL outflows from absorption line variability
FeLoBALs are a rare class of quasar outflows with low-ionization broad
absorption lines (BALs), large column densities, and potentially large kinetic
energies that might be important for `feedback' to galaxy evolution. In order
to probe the physical properties of these outflows, we conducted a
multiple-epoch, absorption line variability study of 12 FeLoBAL quasars
spanning a redshift range between 0.7 and 1.9 over rest frame time-scales of
approximately 10 d to 7.6 yr. We detect absorption line variability with
greater than 8 sigma confidence in 3 out of the 12 sources in our sample over
time-scales of 0.6 to 7.6 yr. Variable wavelength intervals are associated with
ground and excited state Fe II multiplets, the Mg II 2796, 2803 doublet, Mg I
2852, and excited state Ni II multiplets. The observed variability along with
evidence of saturation in the absorption lines favors transverse motions of gas
across the line of sight (LOS) as the preferred scenario, and allows us to
constrain the outflow distance from the supermassive black hole (SMBH) to be
less than 69, 7, and 60 pc for our three variable sources. In combination with
other studies, these results suggest that the outflowing gas in FeLoBAL quasars
resides on a range of scales and includes matter within tens of parsecs of the
central source.Comment: 21 pages, 6 figures, 2 supplementary figures (attached at the end of
the manuscript), accepted to Monthly Notices of the Royal Astronomical
Societ
Trust, Reciprocity and Rules
In the absence of enforceable contracts, many economic and personal interactions rely on trust and reciprocity. Research shows that although this reliance often works well, sometimes it breaks down. Simple rules mandating minimum standards on reciprocation prevent the most egregious trust violations, but may also undermine behavior that would have otherwise produced higher overall economic welfare. We test the efficacy of exogenously imposed minimum return rules using experimental trust games. We find that rules fail to increase trust and trustworthiness. Thus low minimum standards significantly decrease economic welfare. Although sufficiently restrictive rules restore welfare, trust and trustworthy behavior never returns.trust games, experiments, reputation, information, reciprocity
Nesting Success in Ohio's Endangered Common Tern
Author Institution: School of Natural Resources, The Ohio State University ; Ohio Agricultural Research and Development CenterNesting success of Ohio's endangered common tern (Sterna hirundo) population was studied during 1980 at Lucas County Port Authority Facility No. 3 (F3) located near Toledo in Maumee Bay, Lake Erie. Ninety-one clutches in three of eight tern subcolonies at this site were studied in detail. Sixty-nine percent (157/229) of the eggs failed to hatch, and abandonment of nests during incubation was responsible for nearly half of the hatching failures. Most abandonments were believed caused by nocturnal visits to nest sites by a feral cat. Observations at the fourth subcolony indicated that vegetation overgrowing nests and encroachment by juvenile ring-billed gulls (Larus delawarensis) caused additional nest abandonments. Fledging success in the three subcolonies studied in detail was estimated at 0.62 chicks fledged/nest. Production in 1980 was below replacement. Continued reproductive failures will result in extirpation of the common tern from Ohio
Problems involved in establishing a new foundry in the New England area
Thesis (B.S.) Massachusetts Institute of Technology. Dept. of Business and Engineering Administration, 1952.MIT copy bound with: Development of a cost control system for a textile specialty plant / William Edwin Moss. 1952.Bibliography: leaves 106-107.by George M. Shields, Jr., Edward W. Neumann, Jr.B.S
Recoiling Black Holes in Quasars
Recent simulations of merging black holes with spin give recoil velocities
from gravitational radiation up to several thousand km/s. A recoiling
supermassive black hole can retain the inner part of its accretion disk,
providing fuel for a continuing QSO phase lasting millions of years as the hole
moves away from the galactic nucleus. One possible observational manifestation
of a recoiling accretion disk is in QSO emission lines shifted in velocity from
the host galaxy. We have examined QSOs from the Sloan Digital Sky Survey with
broad emission lines substantially shifted relative to the narrow lines. We
find no convincing evidence for recoiling black holes carrying accretion disks.
We place an upper limit on the incidence of recoiling black holes in QSOs of 4%
for kicks greater than 500 km/s and 0.35% for kicks greater than 1000 km/s
line-of-sight velocity.Comment: 4 pages, 4 figures, uses emulateapj, Submitted to ApJ Letter
- …