Signal analysis and error analysis studies for a Geopotential Research Mission (GRM)

The signal characteristics and the geopotential parameter recovery capability of the SST Doppler sensor flown on the geopotential research mission (GRM) are discussed. Simulation studies of the velocity profiles resulting from the perturbation produced by a 1 deg/w/1 deg, 1 mgal anomaly as sensed by two GRM spacecraft orbiting altitudes of 160 km and 200 km respectively are described. It was found that the amplitude of the gravity signal drops off by a factor of 1.5 when going from an altitude of 160 km to 200 km. By extrapolation the signal amplitude is further decreased by a factor of 3 when the orbital altitude is increased to 250 km. Thus the amplitude of the measurement drops off as the altitude is increased to the point where it is insignificant at the 1 mgal level for altitudes above 200 km. Spectral analysis results show that for a GRM mission altitude of 160 km and a system precision of 1 micrometer/sec, gravity field information can be sensed up to 230 cycles per orbital revolution - beyond that frequency the gravity signal is characterized by white noise. It follows that at the GRM mission altitude of 160 km and a satellite to satellite Doppler system precision of 1 micrometer per second, 1/1 deg gravity and geoid anomalies can be determined to an accuracy of 3.4 mgals and 8.6 cm respectively

Gender, Source Country Characteristics and Labor Market Assimilation among Immigrants: 1980-2000

We use 1980, 1990 and 2000 Census data to study the impact of source country characteristics on the labor supply assimilation profiles of married adult immigrant women and men. Women migrating from countries where women have high relative labor force participation rates work substantially more than women coming from countries with lower relative female labor supply rates, and this gap is roughly constant with time in the United States. These differences are substantial and hold up even when we control for wage offers and family formation decisions, as well as when we control for the emigration rate from the United States to the source country. Men's labor supply assimilation profiles are unaffected by source country female labor supply, a result that suggests that the female findings reflect notions of gender roles rather than overall work orientation. Findings for another indicator of traditional gender roles, source country fertility rates, are broadly similar, with substantial and persistent negative effects of source country fertility on the labor supply of female immigrants except when we control for presence of children, in which case the negative effects only become evident after ten years in the United States.fertility, labor supply, immigration, assimilation, gender

Nuptial gift chemistry reveals convergent evolution correlated with antagonism in mating systems of harvestmen (Arachnida, Opiliones)

Nuptial gifts are material donations given from male to female before or during copulation and are subject to sexual selection in a wide variety of taxa. The harvestman genus Leiobunum has emerged as a model system for understanding the evolution of reproductive morphology and behavior, as transitions between solicitous and antagonistic modes of courtship have occurred multiple times within the lineage and are correlated with convergence in genital morphology. We analyzed the free amino acid content of nuptial gift secretions from five species of Leiobunum using gas chromatography–mass spectrometry. Multivariate analysis of the free amino acid profiles revealed that, rather than clustering based on phylogenetic relationships, nuptial gift chemical composition was better predicted by genital morphology and behavior, suggesting that convergent evolution has acted on the chemical composition of the nuptial gift. In addition, we found that, species with solicitous courtship produce gifts consisting of a 19% larger proportion of essential amino acids as compared to those with more antagonistic courtship interactions. This work represents the first comparative study of nuptial gift chemistry within a phylogenetic framework in any animal group and as such contributes to our understanding of the evolution of reproductive diversity and the participant role of nuptial gift chemistry in mating system transitions

Surgical technique of orthotopic liver transplantation

Athough significant strides have been made in the surgical technique of orthotopic liver transplantation, numerous problems and nuisances are still encountered. Further surgical refinements will certainly evolve. The development of better preservation techniques, the use of intraoperative flowmeters, and the availability of new technologies, such as an artificial liver, should impact and advance the techniques of liver transplantation significantly and improve the overall results even further

The Plight of Mixed Race Adolescents

Over the past 40 years, the fraction of mixed race black-white births has increased nearly nine-fold. There is very little empirical evidence on how these children fare relative to their single-race counterparts. This paper describes basic facts about the behaviors and outcomes of black-white mixed race individuals. As one might expect, on a host of background and achievement characteristics as well as adult outcomes, mixed race individuals fall in between whites and blacks. When it comes to engaging in risky and anti-social adolescent behavior, however, mixed race adolescents are stark outliers compared to both blacks and whites. We argue that these behavioral patterns are most consistent with a two-sector Roy model, in which mixed race adolescents – not having a predetermined peer group – engage in more risky behaviors to be accepted.mixed race; biracial; black white race; adolescent behavior

Effect of an antiandrogenic H<inf>2</inf> receptor antagonist on hepatic regeneration in rats

Because biochemical 'feminization' of the liver in males is observed with hepatic regeneration and because the hepatic regenerative response in females is greater than that in males, the posibility that antiandrogens might potentiate liver regeneration was investigated. Before 70% hepatectomy, adult male Wistar rats were treated with cimetidine, and antiandrogenic H2 antagonist, at doses up to 10 times greater than those used clinically. Control animals received either the saline vehicle or ranitidine, an H2 antagonist without antiandrogenic properties. Treatment with cimetidine reduced the hepatic cytosolic androgen receptor content compared with ranitidine treatment. Hepatectomy caused a further reduction in androgen receptor activity in all groups. Hepatic cytosolic estrogen receptor activity was comparable in all groups throughout the study. Moreover, the rate of liver growth and the levels of ornithine decarboxylase and thymidine kinase activity induced as part of the regenerative response were similar in all groups. Thus, cimetidine, despite its ability to bind to androgen receptors, and ranitidine, an H2 receptor antagonist without antiandrogen action, do not modulate the hepatic regenerative response to a 70% partial hepatectomy

Cyclosporine augments hepatic regenerative response in rats

A number of mechanisms participate in the hepatic injury that occurs during and following liver transplantation. A normal allograft regenerative response is probably essential for a successful transplant outcome. In this study, the effect of cyclosporine, a potent immunosuppressant used routinely after liver transplantation, on the regenerative response of the liver after partial hepatectomy was investigated. Male Wistar rats were pretreated for one week with either cyclosporine or the olive oil vehicle and were subjected to either a two-thirds partial hepatectomy or a sham operation. Animals were sacrificed at various times postoperatively and the remnant livers were weighed to determine the liver weight to body weight ratio, two biochemical measures of a regenerative response (cytosolic ornithine decarboxylase activity and thymidine kinase activity), and the hepatic content of estrogen and androgen receptors, as the content of these receptors has been shown to modulate, at least in part, the subsequent hepatic regenerative response. The preoperative hepatic cytosol content of ornithine decarboxylase, thymidine kinase, and estrogen receptor was significantly greater (P<0.05) in rats pretreated with cyclosporine than in those treated with the vehicle alone. A significant increase in ornithine decarboxylase and thymidine kinase activities occurred after partial hepatectomy in both the cyclosporine-pretreated and vehicle-pretreated animals. The absolute levels for each parameter were also greater in the cyclosporine-treated animals than in the vehicle-treated controls at 24 hr after partial hepatectomy (P<0.05). The pattern of change in the hepatic cytosolic content of estrogen and androgen receptors in both groups of animals was comparable with those described previously for regenerating liver. These data suggest that cyclosporine may predispose the liver to respond to either a regenerative signal or perceived need and thereby fortuitously enhance liver graft performance after successful surgical implantation. © 1989 Plenum Publishing Corporation

The Transmission of Women's Fertility, Human Capital and Work Orientation across Immigrant Generations

Using 1995–2006 Current Population Survey and 1970–2000 Census data, we study the intergenerational transmission of fertility, human capital and work orientation of immigrants to their US-born children. We find that second-generation women's fertility and labor supply are significantly positively affected by the immigrant generation's fertility and labor supply respectively, with the effect of mother's fertility and labor supply larger than that of women from the father's source country. The second generation's education levels are also significantly positively affected by that of their parents, with a stronger effect of father's than mother's education. Second-generation women's schooling levels are negatively affected by immigrant fertility, suggesting a quality-quantity tradeoff for immigrant families. We find higher transmission rates for immigrant fertility to the second generation than we do for labor supply or education: after one generation, 40-65% of any immigrant excess fertility will remain, but only 12-18% of any immigrant annual hours shortfall and 18-36% of any immigrant educational shortfall. These results suggest a considerable amount of assimilation across generations toward native levels of schooling and labor supply, although fertility effects show more persistence.immigration, second generation, gender, labor supply, fertility, human capital