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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
Free induction decay of a superposition stored in a quantum dot
We study the free evolution of a superposition initialized with high fidelity
in the neutral-exciton state of a quantum dot. Readout of the state at later
times is achieved by polarized photon detection, averaged over a large number
of cycles. By controlling the fine-structure splitting (FSS) of the dot with a
dc electric field, we show a reduction in the degree of polarization of the
signal when the splitting is minimized. In analogy with the "free induction
decay" observed in nuclear magnetic resonance, we attribute this to hyperfine
interactions with nuclei in the semiconductor. We numerically model this effect
and find good agreement with experimental studies. Our findings have
implications for storage of superpositions in solid-state systems and for
entangled photon pair emission protocols that require a small value of the FSS
The Black Hole Mass - Galaxy Bulge Relationship for QSOs in the SDSS DR3
We investigate the relationship between black hole mass and host galaxy
velocity dispersion for QSOs in Data Release 3 of the Sloan Digital Sky Survey.
We derive black hole mass from the broad Hbeta line width and continuum
luminosity, and the bulge stellar velocity dispersion from the [OIII] narrow
line width. At higher redshifts, we use MgII and [OII] in place of Hbeta and
[OIII]. For redshifts z < 0.5, our results agree with the black hole mass -
bulge velocity dispersion relationship for nearby galaxies. For 0.5 < z < 1.2,
this relationship appears to show evolution with redshift in the sense that the
bulges are too small for their black holes. However, we find that part of this
apparent trend can be attributed to observational biases, including a Malmquist
bias involving the QSO luminosity. Accounting for these biases, we find ~0.2
dex evolution in the black hole mass-bulge velocity dispersion relationship
between now and redshift z ~ 1.Comment: Accepted by ApJ, 15 pages, 9 figure
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
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
Magnetic field dependence of the energy of negatively charged excitons in semiconductor quantum wells
A variational calculation of the spin-singlet and spin-triplet state of a
negatively charged exciton (trion) confined to a single quantum well and in the
presence of a perpendicular magnetic field is presented. We calculated the
probability density and the pair correlation function of the singlet and
triplet trion states. The dependence of the energy levels and of the binding
energy on the well width and on the magnetic field strength was investigated.
We compared our results with the available experimental data on GaAs/AlGaAs
quantum wells and find that in the low magnetic field region (B<18 T) the
observed transition are those of the singlet and the dark triplet trion (with
angular momentum ), while for high magnetic fields (B>25 T) the dark
trion becomes optically inactive and possibly a transition to a bright triplet
trion (angular momentum ) state is observed.Comment: 9 pages, 10 figures submitted to Phys. Rev.
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