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.

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.

Comment on "Nucleon elastic form factors and local duality"

We comment on the papers "Nucleon elastic form factors and local duality" [Phys. Rev. {\bf D62}, 073008 (2000)] and "Experimental verification of quark-hadron duality" [Phys. Rev. Lett. {\bf 85}, 1186 (2000)]. Our main comment is that the reconstruction of the proton magnetic form factor, claimed to be obtained from the inelastic scaling curve thanks to parton-hadron local duality, is affected by an artifact.Comment: to appear in Phys. Rev.

Discovery of a supernova associated with GRB 031203: SMARTS Optical-Infrared Lightcurves from 0.2 to 92 days

Optical and infrared monitoring of the afterglow site of gamma-ray burst (GRB) 031203 has revealed a brightening source embedded in the host galaxy, which we attribute to the presence of a supernova (SN) related to the GRB ("SN 031203"). We present details of the discovery and evolution of SN 031203 from 0.2 to 92 days after the GRB, derived from SMARTS consortium photometry in I and J bands. A template type Ic lightcurve, constructed from SN 1998bw photometry, is consistent with the peak brightness of SN 031203 although the lightcurves are not identical. Differential astrometry reveals that the SN, and hence the GRB, occurred less than 300 h_71^-1 pc (3-sigma) from the apparent galaxy center. The peak of the supernova is brighter than the optical afterglow suggesting that this source is intermediate between a strong GRB and a supernova.Comment: 11 pages, 3 figures, submitted to ApJ Letter

Electromagnetic containerless processing requirements and recommended facility concept and capabilities for space lab

Containerless melting, reaction, and solidification experiments and processes which potentially can lead to new understanding of material science and production of new or improved materials in the weightless space environment are reviewed in terms of planning for spacelab. Most of the experiments and processes discussed are amenable to the employment of electromagnetic position control and electromagnetic induction or electron beam heating and melting. The spectrum of relevant properties of materials, which determine requirements for a space laboratory electromagnetic containerless processing facility are reviewed. Appropriate distributions and associated coil structures are analyzed and compared on the basis of efficiency, for providing the functions of position sensing, control, and induction heating. Several coil systems are found capable of providing these functions. Exchangeable modular coils in appropriate sizes are recommended to achieve the maximum power efficiencies, for a wide range of specimen sizes and resistivities, in order to conserve total facility power

Bloom-Gilman duality of the nucleon structure function and the elastic peak contribution

The occurrence of the Bloom-Gilman duality in the nucleon structure function is investigated by analyzing the Q**2-behavior of low-order moments, both including and excluding the contribution arising from the nucleon elastic peak. The Natchmann definition of the moments has been adopted in order to cancel out target-mass effects. It is shown that the onset of the Bloom-Gilman duality occurs around Q**2 ~ 2 (GeV/c)**2 if only the inelastic part of the nucleon structure function is considered, whereas the inclusion of the nucleon elastic peak contribution leads to remarkable violations of the Bloom-Gilman duality.Comment: in Proc. of the XVI European Conference on Few-body Problems in Physics, Autrans (France), July 199

Dust and dark Gamma-Ray Bursts: mutual implications

In a cosmological context dust has been always poorly understood. That is true also for the statistic of GRBs so that we started a program to understand its role both in relation to GRBs and in function of z. This paper presents a composite model in this direction. The model considers a rather generic distribution of dust in a spiral galaxy and considers the effect of changing some of the parameters characterizing the dust grains, size in particular. We first simulated 500 GRBs distributed as the host galaxy mass distribution, using as model the Milky Way. If we consider dust with the same properties as that we observe in the Milky Way, we find that due to absorption we miss about 10% of the afterglows assuming we observe the event within about 1 hour or even within 100s. In our second set of simulations we placed GRBs randomly inside giants molecular clouds, considering different kinds of dust inside and outside the host cloud and the effect of dust sublimation caused by the GRB inside the clouds. In this case absorption is mainly due to the host cloud and the physical properties of dust play a strong role. Computations from this model agree with the hypothesis of host galaxies with extinction curve similar to that of the Small Magellanic Cloud, whereas the host cloud could be also characterized by dust with larger grains. To confirm our findings we need a set of homogeneous infrared observations. The use of coming dedicated infrared telescopes, like REM, will provide a wealth of cases of new afterglow observations.Comment: 16 pages, 8 figures, accepted by A&

The Influence of Nonmarital Childbearing on the Formation of First Marriages

We examine the association between nonmarital childbearing and the subsequent likelihood of first marriage and document a negative association between these variables controlling for a variety of potentially confounding influences in several large survey data sets for the United States. We then subject possible explanations of this finding to empirical test. The analyses performed support the following conclusions: Nonmarital childbearing does not appear to be driven by low expectations of future marriage. Rather, the direction of causation is just the reverse: Nonmarital childbearing tends to be an unexpected and unwanted event that has multiple effects, which on balance are negative, on a woman's subsequent likelihood of first marriage. Further, the upward trend in the proportion of childbearing that occurs outside of marriage may account for one-fourth of the increase in the proportion of women never marrying in the United States over cohorts separated by almost two decades. We do, however, find that nonmarital childbearers are more likely to enter informal cohabitational unions than are their single counterparts who do not bear a child. We find evidence that the negative association between out-of-wedlock childbearing and subsequent marriage is particularly strong among welfare recipients as well as evidence that out-of-wedlock childbearing increases the likelihood that a woman marries her child's biological father. On the other hand, we find no evidence that (a) stigma associated with nonmarital childbearing plays an important role in this process or (b) the demands of children reduce the time that unmarried mothers have to devote to marriage market activities

Leading-Log Effects in the Resonance Electroweak Form Factors

We study log corrections to inelastic scattering at high Bjorken x for Q^2 from 1 to 21 GeV^2. At issue is the presence of log corrections, which can be absent if high x scattering has damped gluon radiation. We find logarithmic correction of the scaling curve extrapolated to low Q^2 improves the duality between it and the resonance plus background data in the Delta region, indicating log corrections exist in the data. However, at W > 2 GeV and high x, the data shows a (1-x)^3 form. Log corrections in one situation but not in another can be reconciled by a W- or Q^2- dependent higher twist correction.Comment: 13 pages, report nos. RPI-94-N90 and WM-94-106, revtex, two figures (available by fax or post