63,772 research outputs found
Living Standards in Black and White: Evidence from the Heights of Ohio Prison Inmates, 1829 â 1913
The use of height data to measure living standards is now a well-established method in the economic history literature. Moreover, a number of core findings in this literature are widely agreed upon. There are still some populations, places, and times, however, for which anthropometric evidence remains thin. One example is African-Americans in the Northern US in the 1800s. Here, we use new data from the state prison in Ohio to track heights of black and white men from 1829 to 1913. We corroborate the well-known mid-century height decline among white men in Ohio, found by Steckel and Haurin (1994) using National Guard data. We find that black men in Ohio were shorter than white men, throughout the century and controlling for a number of characteristics. We also find a pattern of height decline in mid-century similar to that found for white men.
Localizing coalescing massive black hole binaries with gravitational waves
Massive black hole binary coalescences are prime targets for space-based
gravitational wave (GW) observatories such as {\it LISA}. GW measurements can
localize the position of a coalescing binary on the sky to an ellipse with a
major axis of a few tens of arcminutes to a few degrees, depending on source
redshift, and a minor axis which is times smaller. Neglecting weak
gravitational lensing, the GWs would also determine the source's luminosity
distance to better than percent accuracy for close sources, degrading to
several percent for more distant sources. Weak lensing cannot, in fact, be
neglected and is expected to limit the accuracy with which distances can be
fixed to errors no less than a few percent. Assuming a well-measured cosmology,
the source's redshift could be inferred with similar accuracy. GWs alone can
thus pinpoint a binary to a three-dimensional ``pixel'' which can help guide
searches for the hosts of these events. We examine the time evolution of this
pixel, studying it at merger and at several intervals before merger. One day
before merger, the major axis of the error ellipse is typically larger than its
final value by a factor of . The minor axis is larger by a factor
of , and, neglecting lensing, the error in the luminosity distance is
larger by a factor of . This large change over a short period of
time is due to spin-induced precession, which is strongest in the final days
before merger. The evolution is slower as we go back further in time. For , we find that GWs will localize a coalescing binary to within $\sim 10\
\mathrm{deg}^2$ as early as a month prior to merger and determine distance (and
hence redshift) to several percent.Comment: 30 pages, 10 figures, 5 tables. Version published in Ap
Classification of n-qubit states with minimum orbit dimension
The group of local unitary transformations acts on the space of n-qubit pure
states, decomposing it into orbits. In a previous paper we proved that a
product of singlet states (together with an unentangled qubit for a system with
an odd number of qubits) achieves the smallest possible orbit dimension, equal
to 3n/2 for n even and (3n + 1)/2 for n odd, where n is the number of qubits.
In this paper we show that any state with minimum orbit dimension must be of
this form, and furthermore, such states are classified up to local unitary
equivalence by the sets of pairs of qubits entangled in singlets.Comment: 15 pages, latex, revision 2, conclusion added, some proofs shortene
Nonlinear surface impurity in a semi-infinite 2D square lattice
We examine the formation of localized states on a generalized nonlinear
impurity located at, or near the surface of a semi-infinite 2D square lattice.
Using the formalism of lattice Green functions, we obtain in closed form the
number of bound states as well as their energies and probability profiles, for
different nonlinearity parameter values and nonlinearity exponents, at
different distances from the surface. We specialize to two cases: impurity
close to an "edge" and impurity close to a "corner". We find that, unlike the
case of a 1D semi-infinite lattice, in 2D, the presence of the surface helps
the formation of a localized state.Comment: 6 pages, 7 figures, submitted to PR
Classification of nonproduct states with maximum stabilizer dimension
Nonproduct n-qubit pure states with maximum dimensional stabilizer subgroups
of the group of local unitary transformations are precisely the generalized
n-qubit Greenberger-Horne-Zeilinger states and their local unitary equivalents,
for n greater than or equal to 3 but not equal to 4. We characterize the Lie
algebra of the stabilizer subgroup for these states. For n=4, there is an
additional maximal stabilizer subalgebra, not local unitary equivalent to the
former. We give a canonical form for states with this stabilizer as well.Comment: 6 pages, version 3 has a typographical correction in the displayed
equation just after numbered equation (2), and other minor correction
Cutting costs in calf rearing
RAISING calves as herd replacements and as a sideline to provide added income is becoming increasingly popular.
This is particularly noticeable since the inception of the Artificial Breeding Scheme whereby farmers are at liberty to breed herd replacements from their most productive cows and use semen from beef breeds for the poorer types
Debris/ice/TPS assessment and integrated photographic analysis for Shuttle Mission STS-54
A Debris/Ice/TPS assessment and integrated photographic analysis was conducted for Shuttle Mission STS-54. Debris inspections of the flight elements and launch pad were performed before and after launch. Ice/frost conditions on the External Tank were assessed by the use of computer programs, nomographs, and infrared scanner data during cryogenic loading of the vehicle followed by on-pad visual inspection. High speed photography was analyzed after launch to identify ice/debris sources and evaluate potential vehicle damage and/or in-flight anomalies. This report documents the debris/ice/TPS conditions and integrated photographic analysis of Shuttle Mission STS-54, and the resulting effect on the Space Shuttle Program
Dissipative solitons which cannot be trapped
In this paper we study the behavior of dissipative solitons in systems with
high order nonlinear dissipation and show how they cannot survive under the
effect of trapping potentials both of rigid wall type or asymptotically
increasing ones. This provides an striking example of a soliton which cannot be
trapped and only survives to the action of a weak potential
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