260,196 research outputs found
Estimating distributions of potential outcomes using local instrumental variables with an application to changes in college enrollment and wage inequality
This paper extends the method of local instrumental variables developed by Heckman and Vyt-
lacil (1999, 2001, 2005) to the estimation of not only means, but also distributions of potential
outcomes. The newly developed method is illustrated by applying it to changes in college enroll-
ment and wage inequality using data from the National Longitudinal Survey of Youth of 1979.
Increases in college enrollment cause changes in the distribution of ability among college and high
school graduates. This paper estimates a semiparametric selection model of schooling and wages to
show that, for fixed skill prices, a 14% increase in college participation (analogous to the increase
observed in the 1980s), reduces the college premium by 12% and increases the 90-10 percentile ratio
among college graduates by 2
Recommended from our members
Gullies on Mars: Origin by snow and ice melting and potential for life based on possible analogs from Devon Island, High Arctic
Gullies on Devon Island, High Arctic, which form by melting of transient surface ice and snow covers and offer morphologic and contextual analogs for gullies reported on Mars are reported to display enhancements in biological activity in contrast to surrounding polar desert terrain
N-Triflylphosphorimidoyl Trichloride: A Versatile Reagent for the Synthesis of Strong Chiral BrĂžnsted Acids
A series of strong BrĂžnsted acids has been synthesized in high yields using N-triflylphosphorimidoyl trichloride as reagent. The syntheses proceed efficiently with electron-rich, electron-deficient, and sterically hindered substrates
U(1) Gauge Theory of the Hubbard Model : Spin Liquid States and Possible Application to k-(BEDT-TTF)_2 Cu_2 (CN)_3
We formulate a U(1) gauge theory of the Hubbard model in the slave-rotor
representation. From this formalism it is argued that spin liquid phases may
exist near the Mott transition in the Hubbard model on triangular and honeycomb
lattices at half filling. The organic compound k-(BEDT-TTF)_2 Cu_2 (CN)_3 is a
good candidate for the spin liquid state on a triangular lattice. We predict a
highly unusual temperature dependence for the thermal conductivity of this
material.Comment: 5 pages, 2 figures; paper shortened and the phase diagram of
anisotropic triangular lattice correcte
Double-heterostructure GaAs-GaAIAs injection lasers on semi-insulating substrates using carrier crowding
GaAsâGaAlAs doubleâheterostructure lasers were fabricated on semiâinsulating substrates. Laser action based on carrier confinement via the crowding effect has been demonstrated. Laser action takes place in a narrow (10â20 ÎŒm) region near the edge of the mesa where the current is injected. The threshold current is low and is comparable to that of stripeâgeometry lasers
Reply to "Comment on 'Scalar-tensor gravity coupled to a global monopole and flat rotation curves' "
In Brans-Dicke theory of gravity we explain how the extra constant value in
the formula for rotation velocities of stars in a galactic halo can be obtained
due to the global monopole field. We argue on a few points of the preceding
Comment and discuss improvement of our model.Comment: 4 pages, RevTeX4 fil
Superconducting energy gap in MgCNi3 single crystals: Point-contact spectroscopy and specific-heat measurements
Specific heat has been measured down to 600 mK and up to 8 Tesla by the
highly sensitive AC microcalorimetry on the MgCNi3 single crystals with Tc ~ 7
K. Exponential decay of the electronic specific heat at low temperatures proved
that a superconducting energy gap is fully open on the whole Fermi surface, in
agreement with our previous magnetic penetration depth measurements on the same
crystals. The specific-heat data analysis shows consistently the strong
coupling strength 2D/kTc ~ 4. This scenario is supported by the direct gap
measurements via the point-contact spectroscopy. Moreover, the spectroscopy
measurements show a decrease in the critical temperature at the sample surface
accounting for the observed differences of the superfluid density deduced from
the measurements by different techniques
- âŠ