30,683 research outputs found
Marriage Patterns in the United States
This paper analyzes cohort marriage patterns in the United States in order to determine whether declining rates of first marriage are due to changes in the timing of marriage, the incidence of marriage, or both. Parametric models, which are well-suited to the analysis of censored or truncated data, are fit separately to information on age at first marriage derived from three data sets which were collected independently and at different points in time. Extended versions of the models are also estimated in which the parameters of the model distributions are allowed to depend on social and, economic variables.The results provide evidence that the incidence of first marriage is declining and that there is only a slight tendency for women to delay marriage. In addition, education is the most important correlate of decisions about the timing of first marriage whereas race is the most important correlate of decisions about its incidence.
The Impact of Line Misidentification on Cosmological Constraints from Euclid and other Spectroscopic Galaxy Surveys
We perform forecasts for how baryon acoustic oscillation (BAO) scale and
redshift-space distortion (RSD) measurements from future spectroscopic emission
line galaxy (ELG) surveys such as Euclid are degraded in the presence of
spectral line misidentification. Using analytic calculations verified with mock
galaxy catalogs from log-normal simulations we find that constraints are
degraded in two ways, even when the interloper power spectrum is modeled
correctly in the likelihood. Firstly, there is a loss of signal-to-noise ratio
for the power spectrum of the target galaxies, which propagates to all
cosmological constraints and increases with contamination fraction, .
Secondly, degeneracies can open up between and cosmological parameters.
In our calculations this typically increases BAO scale uncertainties at the
10-20% level when marginalizing over parameters determining the broadband power
spectrum shape. External constraints on , or parameters determining the
shape of the power spectrum, for example from cosmic microwave background (CMB)
measurements, can remove this effect. There is a near-perfect degeneracy
between and the power spectrum amplitude for low values, where
is not well determined from the contaminated sample alone. This has the
potential to strongly degrade RSD constraints. The degeneracy can be broken
with an external constraint on , for example from cross-correlation with a
separate galaxy sample containing the misidentified line, or deeper
sub-surveys.Comment: 18 pages, 7 figures, updated to match version accepted by ApJ (extra
paragraph added at the end of Section 4.3, minor text edits
Supercatalysis
We show that entanglement-assisted transformations of bipartite entangled
states can be more efficient than catalysis [D. Jonathan and M. B. Plenio,
Phys. Rev. Lett. 83, 3566 (1999)}, i.e., given two incomparable bipartite
states not only can the transformation be enabled by performing collective
operations with an auxiliary entangled state, but the entanglement of the
auxiliary state itself can be enhanced. We refer to this phenomenon as
supercatalysis. We provide results on the properties of supercatalysis and its
relationship with catalysis. In particular, we obtain a useful necessary and
sufficient condition for catalysis, provide several sufficient conditions for
supercatalysis and study the extent to which entanglement of the auxiliary
state can be enhanced via supercatalysis.Comment: Latex, 5 page
Calculation of transonic steady and oscillatory pressures on a low aspect ratio model and comparison with experiment
Pressure data measured by the British Royal Aircraft Establishment for the AGARD SMP tailplane are compared with results calculated using the transonic small perturbation code XTRAN3S. A brief description of the analysis is given and a recently developed finite difference grid is described. Results are presented for five steady and nine harmonically oscillating cases near zero angle of attack and for a range of subsonic and transonic Mach numbers
Commitment and the Modern Union: Assessing the Link Between Premarital Cohabitation and Subsequent Marital Stability
In recent years, the incidence of premarital cohabitation has increased dramatically in many countries of Western Europe and in the United States. As cohabitation becomes a more common experience, it is increasingly important to understand the links between cohabitation and other steps in the process of family formation and dissolution. We focus on the relationship between pre- marital cohabitation and subsequent marital stability, and analyze data from the 1981 Women in Sweden survey using a hazards model approach. Our results indicate that women who premaritally cohabit have almost 80 percent higher marital dissolution rates than those who do not cohabit. Women who cohabit for over three years prior to marriage have over 50 percent higher dissolution rates than women who cohabit for shorter durations. Last, cohabitors and non-cohabitors whose marriages have remained intact for eight years appear to have identical dissolution rates after that time. In addition, we provide evidence that strongly suggests a weaker commitment, on the part of those who cohabit premaritally, to the institution of marriage.
A classical analogue of entanglement
We show that quantum entanglement has a very close classical analogue, namely
secret classical correlations. The fundamental analogy stems from the behavior
of quantum entanglement under local operations and classical communication and
the behavior of secret correlations under local operations and public
communication. A large number of derived analogies follow. In particular
teleportation is analogous to the one-time-pad, the concept of ``pure state''
exists in the classical domain, entanglement concentration and dilution are
essentially classical secrecy protocols, and single copy entanglement
manipulations have such a close classical analog that the majorization results
are reproduced in the classical setting. This analogy allows one to import
questions from the quantum domain into the classical one, and vice-versa,
helping to get a better understanding of both. Also, by identifying classical
aspects of quantum entanglement it allows one to identify those aspects of
entanglement which are uniquely quantum mechanical.Comment: 13 pages, references update
Irreversibility in asymptotic manipulations of entanglement
We show that the process of entanglement distillation is irreversible by
showing that the entanglement cost of a bound entangled state is finite. Such
irreversibility remains even if extra pure entanglement is loaned to assist the
distillation process.Comment: RevTex, 3 pages, no figures Result on indistillability of PPT states
under pure entanglement catalytic LOCC adde
Angular Power Spectrum of the Microwave Background Anisotropy seen by the COBE Differential Microwave Radiometer
The angular power spectrum estimator developed by Peebles (1973) and Hauser &
Peebles (1973) has been modified and applied to the 2 year maps produced by the
COBE DMR. The power spectrum of the real sky has been compared to the power
spectra of a large number of simulated random skies produced with noise equal
to the observed noise and primordial density fluctuation power spectra of power
law form, with . Within the limited range of spatial scales
covered by the COBE DMR, corresponding to spherical harmonic indices 3 \leq
\ell \lsim 30, the best fitting value of the spectral index is with the Harrison-Zeldovich value approximately
0.5 below the best fit. For 3 \leq \ell \lsim 19, the best fit is . Comparing the COBE DMR at small to
the at from degree scale anisotropy experiments
gives a smaller range of acceptable spectral indices which includes .Comment: 22 pages of LaTex using aaspp.sty and epsf.sty with appended
Postscript figures, COBE Preprint 94-0
Roll diffusion bonding of titanium alloy panels
Roll diffusion bonding technique is used for fabricating T-stiffened panel assemblies from titanium alloy. The single unit fabrication exhibits excellent strength characteristics under tensile and compressive loads. This program is applied to structures in which weight/strength ratio and integral construction are important considerations
Unconditionally secure quantum bit commitment is impossible
The claim of quantum cryptography has always been that it can provide
protocols that are unconditionally secure, that is, for which the security does
not depend on any restriction on the time, space or technology available to the
cheaters. We show that this claim does not hold for any quantum bit commitment
protocol. Since many cryptographic tasks use bit commitment as a basic
primitive, this result implies a severe setback for quantum cryptography. The
model used encompasses all reasonable implementations of quantum bit commitment
protocols in which the participants have not met before, including those that
make use of the theory of special relativity.Comment: 4 pages, revtex. Journal version replacing the version published in
the proceedings of PhysComp96. This is a significantly improved version which
emphasis the generality of the resul
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