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1.
Abstract The present research focuses on childed versus childless intentions and subsequent behavior and intentions for a panel of U. S. women. Utilizing data from the 1970 and 1975 National Fertility Surveys (reinterviewed women), we ascertain the consistency between intentions (1970) and behavior and intentions (1975). We find that while women who expressed a zero parity intention in 1970 were very consistent in their behavior and intentions in 1975, nearly 30 per cent of those women intending children had no children by 1975. Furthermore, of these 30 per cent, one‐third had changed their intention to zero parity by 1975. We find that changing intentions from more than zero to zero is associated with higher levels of education, slightly higher income, and to a lesser degree with the importance given religion and with labor force participation. 相似文献
2.
Abstract The method of fertility projection used by the U.S. Bureau of the Census involves assumptions about the ultimate cohort total fertility rate and the ultimate cohort mean age at childbearing based on recent levels of fertility and women's birth expectations. This paper provides an outline of a general regression approach to fertility projection based on past data which would generate these two ultimate cohort characteristics. The technique is illustrated by using the U.S. single‐year age‐specific fertility rates up to 1986 for total women and projecting them indefinitely into the future until they become stable for both calendar years and cohorts. 相似文献
3.
Using data from the 1965 U.S. National Fertility Study, white childless wives 30-54 years old were categorized as voluntarily, involuntarily, or temporarily childless. These 3 groups were then compared along many demographic, socioeconomic, marital, and religious lines. It was found that voluntarily and involuntarily childless wives were similar across most characteristics and both groups were different from the temporarily childless women. This last group is considerably younger than either of the other 2 groups; this fact may account for the differences between this and the other 2 groups. Other literature on childlessness is cited and compared. The difficulties with categorization of childless wives are discussed. Before it is generally concluded that differences do not exist between voluntarily and involuntarily childless wives, it will be necessary to study data from younger women who benefited from the "new fertility regime" of recent years. 相似文献
4.
BackgroundAcross major races in the United States (U.S.), ovarian cancer incidence is low among Asian American women. However, this observation aggregates Asian Americans as a single group despite their heterogeneity. Disaggregating the ethnic Asian population will produce more useful information to better understand ovarian cancer incidence among Asian women in the U.S. MethodsData from the Surveillance, Epidemiology, and End Results Program from 1990 to 2014 were used to compare age-adjusted incidence rates (AAIRs, per 100,000 women) for ovarian cancer for the six largest U.S. Asian ethnicities (Asian Indian/Pakistani, Chinese, Filipino, Japanese, Korean, Vietnamese) to non-Hispanic whites (NHWs). The race/ethnicity-specific AAIRs were calculated by time period and histotype. We examined the magnitude and direction of AAIR trends using average annual percent change (AAPC) statistics. ResultsAll Asian ethnicities had significantly lower ovarian cancer incidence rates than NHWs. However, among Asian ethnicities, Asian Indians/Pakistanis had the highest rate of ovarian cancer (AAIR = 10.51, 95% CI: 9.65–11.42) while Koreans had the lowest (AAIR = 7.23, 95% CI: 6.62–7.88). Clear cell ovarian cancer had significantly higher incidence rates among Chinese, Filipino, and Japanese women than NHW women (incidence rate ratio (IRR) = 1.49, 95% CI: 1.29–1.72, IRR = 1.30, 95% CI: 1.12–1.51, IRR = 1.64, 95% CI: 1.36–1.97, respectively). Incidence trends also differed by Asian ethnicity with significant decreases only observed for Chinese (AAPC = −1.49, 95% CI: −2.22 to −0.74) and Japanese (AAPC = −1.75, 95% CI: −2.57 to −0.92). ConclusionsExamining Asian Americans as a single group results in missed ethnic-specific disparities in ovarian cancer, hence disaggregating this heterogeneous population in future research is warranted. 相似文献
5.
Using data from the first Census data set that includes complete measures of male biological fertility for a large-scale probability sample of the U.S. population (the 2014 wave of the Study of Income and Program Participation- N = 55,281), this study shows that high income men are more likely to marry, are less likely to divorce, if divorced are more likely to remarry, and are less likely to be childless than low income men. Men who remarry marry relatively younger women than other men, on average, although this does not vary by personal income. For men who divorce who have children, high income is not associated with an increased probability of having children with new partners. Income is not associated with the probability of marriage for women and is positively associated with the probability of divorce. High income women are less likely to remarry after divorce and more likely to be childless than low income women. For women who divorce who have children, high income is associated with a lower chance of having children with new partners, although the relationship is curvilinear. These results are behavioral evidence that women are more likely than men to prioritize earning capabilities in a long-term mate and suggest that high income men have high value as long-term mates in the U.S. 相似文献
6.
脑科学是生命科学领域的研究前沿和热点,美国是该领域的科技强国。本文基于科技论文和专利数据,利用文献计量学的定量分析方法,比较中国和美国在脑科学领域的理论研究和应用研究的差距。结果表明,基于论文分析的理论研究对比,发现中国较美国起步晚,目前论文数量上的差距正在缩小,但学术影响力的差距较大;基于专利分析的应用研究对比,发现中国在专利申请数量上已略超过美国,但在代表专利技术价值和市场价值的国际专利数量、技术布局、龙头企业及企业参与研发比重等方面,差距还非常之大。 相似文献
7.
BackgroundPrevious studies have not examined young adult cancer incidence trends in Taiwan, or comprehensively compared these trends at two nations with different population genetics, environmental exposures, and health care. Therefore, we compared the incidence rates and trends of the most common young adult cancers diagnosed at 20–39 years of age in Taiwan and the U.S. MethodsIncidence rates from 2002 to 2016 were calculated from the Taiwan National Health Insurance Research Datasets and the U.S. Surveillance, Epidemiology, and End Results Program. For trend assessment, average annual percent change (AAPC) values were calculated from 15 years of data using Joinpoint Regression Program. We also obtained sex or age of diagnosis stratified estimates. ResultsThe age-standardized overall young adult cancer incidence rate significantly increased from 2002 to 2016 in both Taiwan (AAPC=1.1%, 95% CI: 0.8–1.5%) and the U.S. (AAPC=1.8%, 95% CI: 1.1–2.4%). Cancers with significantly decreasing trends in Taiwan included cancers of the nasopharynx, liver, and tongue, which were not among the most common young adult cancers in the U.S. Cancers with significantly increasing trends in both Taiwan and the U.S. included colorectal, thyroid, and female breast cancers. Lymphoma, ovarian cancer, and lung and bronchus cancer had significantly increasing trends in Taiwan but not in the U.S. Although cervical cancer had significantly decreasing trends in both nations among those 30–39 years of age, its trend was significantly increasing in Taiwan but decreasing in the U.S. among those 20–29 years of age. ConclusionThe types of common young adult cancers as well as their incidence rates and trends differed in Taiwan and the U.S. Future studies should further understand the etiological factors driving these trends. 相似文献
8.
Abstract It has been argued that the issuance of the U.S. Exclusive Economic Zone (EEZ) Proclamation could lead to difficulties in the management of our coastal resources. This paper will examine the consequences of a U.S. EEZ for fisheries and marine transportation. For each sector consideration will be given to the inconsistencies which exist between the United Nations Convention on the Law of the Sea, the U.S. Proclamation, and existing U.S. legislation. The problems and opportunities presented by these inconsistencies are discussed. The authors conclude that, while some modifications of U.S. policy may be required, wide‐ranging changes are neither likely nor needed. 相似文献
9.
Objective: To determine the influence of environmental factors on resting energy expenditure (REE) and its relationship to adiposity in two populations of West African origin, Nigerians and U.S. blacks. Research Methods and Procedures: REE and body composition were measured in a cross‐sectional sample of 89 Nigerian adults (39 women and 50 men), and 181 U.S. black adults (117 women and 65 men). Both groups represent randomly selected population samples. REE was measured by indirect calorimetry after an overnight fast in both sites using the same instrument. Body composition was estimated using bioelectrical impedance analysis (BIA) in 72 Nigerians and 156 U.S. participants. Multivariate regression analysis was used to determine the significant predictors of REE. The analyses were repeated in a set of 17 Nigerians and 28 U.S. blacks in whom body composition was measured using deuterium dilution. Results: U.S. black adults were significantly heavier and had both more fat‐free mass (FFM) and body fat than Nigerians. FFM was the only significant determinant of REE in both population groups, whether body composition was measured using BIA or deuterium dilution. The relationship between REE and body composition did not differ by site. There was no relationship between REE and adiposity. Discussion: Differences in current environmental settings did not impact REE. The differences observed in mean levels of body fat between Nigerians and U.S. blacks were not the result of differences in REE adjusted for body composition. 相似文献
10.
Abstract We examine whether age at menarche affects age at first marriage or first birth using two samples of U.S. women. Data are drawn from the Tremin Trust, a longitudinal study of menstrual cycles that recruited white women who were students at the University of Minnesota and from a survey of a nationally representative sample of white women born between 1900 and 1910. Regression models with cubic splines were used to analyze the relationship between age at menarche and age at first marriage. Cox proportional hazard models were used to examine the effect of age at menarche on the interval between marriage and first birth. Unlike earlier work, we found that once secular trends in both age at marriage and age at menarche were taken into account, there was no evidence that age at menarche affects either age at marriage or the timing of first births in these U.S. women. 相似文献
11.
Abstract The rate of childlessness in the United States has increased over the last two decades. Changing or differential rates by different segments of society have important implications for society. Most previous studies have relied on unrepresentative opportunistic samples to identify those segments of society with lower or higher rates of childlessness. These types of samples may misestimate both the number of women planning to remain childless and the magnitude of the correlates of childlessness. The present study uses these previous studies to identify predictor variables, but tests their significance using a recent national representative sample of women in the United States, aged 20–44: Cycle III of the National Survey for Family Growth, collected in 1982. The most important demographic factors are marital status and fecundity status, followed by age, race or ethnicity, education of the respondent, labor force status, and region. Father's education and mother's education are slightly, but not significantly, related to childlessness. Contrary to findings from less representative samples, urban‐rural differences and religion are not related to childlessness. 相似文献
12.
The reliability of ONIOM approach have been examined in calculations of adsorption energies, transition structures, change
of HOMO-LUMO energy gaps and equilibrium geometries of the interaction between NH 3 and N-enriched ( A) or B-enriched ( B) open ended boron nitride nanotubes. To these ends, four models of the A or B, with different inner and outer layers have been studied. In addition, various low-levels including, AM1, PM3, MNDO and UFF
have been examined, applying B3LYP/6-31 G* in all high-levels. It was shown, that in the case of A, (choosing two atom layers of the tube open-end as inner layer) the results of ONIOM approach are in best agreement with
those of the pure density functional theory (DFT) calculations, while their results significantly differ from those of DFT
in the case of B in same conditions. All above and population analysis demonstrate that the ONIOM may be a reliable scheme in the study of
weak interactions while it is a controversial approach and should be applied cautiously in the case of strong interactions.
We also probed the effect of tube length and diameter on the consistency between ONIOM and DFT results, showing that this
consistency is independent of the mentioned parameters. 相似文献
13.
Saccharopine dehydrogenase catalyzes the NAD-dependent conversion of saccharopine to generate l-lysine and α-ketoglutarate. A disulfide bond between cysteine 205 and cysteine 249, in the vicinity of the dinucleotide-binding site, is observed in structures of the apoenzyme, while a dithiol is observed in a structure with AMP bound, suggesting preferential binding of the dinucleotide to reduced enzyme. Mutation of C205 to S gave increased values of V/ Et and V/ KEt at pH 7 compared to wild type. Primary deuterium and solvent deuterium kinetic isotope effects suggest the catalytic pathway, which includes the hydride transfer and hydrolysis steps, contributes more to rate limitation in C205S, but the rates of the two steps relative to one another remain the same. There is a large increase in the rate constants V1/ Et and V1/K NADEt at pH values below 7 compared to WT. Data indicate the low pH increase in activity results from a decreased sensitivity of the C205S mutant enzyme to the protonation state of an enzyme group with a p Ka of about 7, likely responsible for a pH-dependent conformational change. Reduction of WT and C205S mutant enzymes with TCEP gives equal activities at pH 6, consistent with the increased activity observed for the C205S mutant enzyme. 相似文献
14.
ObjectivesTime trends on the incidence and characteristics of invasive vulvar cancer in Germany have so far been studied in few local population- and hospital based tumor registries. We aimed to provide an overview on recent developments of vulvar cancer in Germany, using population-based cancer registry data. MethodsWe analyzed the data on vulvar cancer of eight population-based German cancer registries for the period 1999-2011. ICD-10 codes and ICD-O-3 morphology codes were used to select site and histologic types. The annual percentage change was calculated on age-adjusted incidence rates with a joinpoint regression model. ResultsA total of 12,711 registered cases of invasive carcinoma of the vulva were included in the analyses, hereof were 12,205 of squamous cell origin. Age-standardized incidence rates of vulvar cancer annually increased by 6.7% (95% confidence limits: 5.6-7.9) from 1.7 per 100,000 women in 1999 to 3.6 per 100,000 women in 2011. An increase was observed among women of all ages, and especially between 30 and 69 years of age. ConclusionThe annual incidence of invasive carcinoma of the vulva nearly doubled in the past decade in Germany, considerably exceeding the rates observed in other Western European countries. A combination of changes in risk factors, and documentation practice might have contributed to the observed substantial increase in vulvar cancer incidence. 相似文献
15.
AimThe main goal of this investigation was to evaluate the influence of positive Staphylococcus aureus culture from the genital tract on patients receiving radiation therapy, suffering from carcinoma of the uterus. The other aim was to observe radiation therapy complications. BackgroundRadiation therapy of patients suffering from cervical cancer can be connected with inflammation of the genitourinary tract. Materials and methodsIn years 2006–2010 vaginal swabs from 452 patients were examined. 39 women with positive S. aureus cultures were analysed. ResultsComplications and interruptions during radiation therapy were observed in 7 (18.9%) of 37 patients with positive vaginal S. aureus culture. One of them, a 46-year-old woman developed pelvic inflammatory disease. None of the six patients who received palliative radiotherapy showed interruption in this treatment. Isolated S. aureus strains were classified into 13 sensitivity patterns, of which 8 were represented by 1 strain, two by 2 strains and three by 13, 8 and 6 strains. One strain was diagnosed as methicillin resistant S. aureus (MRSA). ConclusionsThe results of the present study show that S. aureus may generally be isolated from the genital tract of female patients with neoplastic disease of uterus but is not often observed as inflammation factor of this tract. Comparison of species’ resistance patterns may be used in epidemiological studies in order to discover the source of infections and therefore be of profound significance in the prevention of nosocomial infections. 相似文献
16.
Abstract In the last decade, the world has witnessed a fundamental reorientation of posture toward marine resources as evidenced by consensus in the Third United Nations Conference on the Law of the Sea (UNCLOS III) and the near universal move toward fishery jurisdictions of 200 nautical miles (370 km). These and other non‐marine‐specific economic and political pressures impose a new constellation of constraints on North American fishery relations. This has resulted in disharmonies on two borders. This paper, then, addresses the form of binational fishery negotiations between the United States and her two neighbors. One section presents a general model of the binational negotiation process. The next section introduces the institutional and political context of U.S.‐Canada relations, and then applies the negotiation model to the evolution of West Coast salmon deliberations. In a parallel fashion, the following section focuses on U.S.‐Mexico relations and the tuna, shrimp, and anchovy fisheries. The last section concludes with remarks on future directions for North American binational fishery relations. 相似文献
17.
The genus Urochloa P. Beauv. presents a prominent role in the tropical agricultural scenario being composed of species with different ploidy levels. Studies on the genomic relationship within this genus as well as specific analysis involving epigenetic marks are limited. The aim of the present study was to identify the cytosine methylation (5-mCyt) and histone H3 lysine 9 dimethylation (H3k9me2) in the different modulations of 45S ribosomal DNA (rDNA) sites in interphase nuclei and to associate these results with gene expression analysis in Urochloa ruziziensis (2n = 4x = 36), Urochloa brizantha cv. Marandu (2n = 4x = 36), and their respective interspecific hybrid H1863 (2n = 4x = 36). Immunolocalization techniques were performed in combination with Fluorescence in situ hybridization (FISH) for the location of the 45S rDNA sites. Predominantly, we observed intra- and perinucleolar sites, mostly hypomethylated and/or hyper/hypomethylated, decondensed or partially condensed. The gene expression analysis was performed qualitatively through the conventional PCR using complementary DNA and confirmed by the RT-qPCR technique and primers designed for the ITS-1 region of U. brizantha and U. ruziziensis. The molecular analyses performed on leaves showed that there is dominance of U. brizantha 45S rDNA gene expression on U. ruziziensis in the H1863 hybrid. In roots, the analyses showed that the 45S rDNA genes of the two parents are expressed in the hybrid genome. Thus, it is plausible to infer a tissue-specific nuclear dominance model in which the pattern of hypermethylated cytosine sites with heterochromatic marks and, therefore, silenced were mostly inherited from U. ruziziensis, whereas the rDNA originated from U. brizantha was characterized by cytosine and H3k9 hypomethylation. 相似文献
18.
Abstract In this study, data from the New Immigrant Survey and the National Health and Nutrition Examination Survey are combined to examine patterns of overweight and obesity among U.S.‐born and foreign‐born Hispanics. Results indicate that, after using height and weight measures adjusted for self‐reporting bias, foreign‐born Hispanic men and women have substantially lower likelihoods of being overweight and obese than the U.S.‐born. However, both likelihoods increase as years in the U.S. accumulate for the foreign‐born. Controls for smoking behavior, physical activity, and the degree of dietary change do not reduce the strength of the positive relationship between years in the U.S. and overweight/obesity. 相似文献
19.
BackgroundWhile breast cancer incidence and mortality rates differ across racial/ethnic populations in the U.S., little is known about Asian and Pacific Island subpopulations. Hawaii is one of the most racially/ethnically diverse states in the U.S. Overall, Hawaii ranks 5 th highest for breast cancer incidence in the nation (2010–2014) and rates have increased in recent years despite a stable national trend. In contrast, for breast cancer mortality, Hawaii has the 3 rd lowest rate in the nation, with rates demonstrating a steady decline for nearly 3 decades. MethodsWe examined incidence and mortality trends from 1984–2013 across the five major racial/ethnic populations of Hawaii (Native Hawaiian, White, Japanese, Chinese, and Filipino) using Hawaii’s Surveillance, Epidemiology, and End Results (SEER) registry data. ResultsWith the exception of Chinese, all groups experienced increasing incidence over the thirty year period. While Japanese experienced the most pronounced recent increase, with incidence now exceeding that of Whites, their mortality rates have remained low for decades. Native Hawaiians have consistently had the highest incidence and mortality rates in the state. The incidence rates of hormone receptor (HR)-positive breast cancer were higher among Japanese and Native Hawaiians as compared to Whites. Relative to Whites, Native Hawaiians also had a higher incidence rate of the HER2-positive subtype and, Japanese, of the triple-negative (HR-/HER2-) subtype of breast cancer. ConclusionsStudies such as this underscore the importance of considering the heterogeneity in breast cancer rates and subtypes across the different racial/ethnic populations. 相似文献
20.
BackgroundCancers of unknown primary (CUP), a group of heterogenous metastatic cancers lacking a known primary site, have poor prognosis. This study compared survival of CUP by histologic type, patient characteristics, and treatment in the U.S. Military Health System (MHS), which provides universal care to its members. MethodsPatients histologically diagnosed with CUP were identified from the U.S. Department of Defense (DoD)’s Automated Central Tumor Registry. Median survival with 95 % confidence intervals was calculated for demographic and treatment variables by histologic type. A multivariable accelerated failure time model estimated time ratios and 95 % confidence intervals. ResultsThe study included 3358 CUP patients. The most prevalent CUP in this study was well- and moderately-differentiated adenocarcinomas. Median survival varied by histologic type with squamous cell carcinoma having the longest at 25.1 months and poorly-differentiated carcinomas having the shortest at 3.0 months. For each histologic type, survival was generally similar by sex and active-duty status although women with well- and moderately-differentiated adenocarcinoma had longer survival than their male counterparts. Younger patients tended to have longer survival than those aged 65 years or older. Generally, there were no racial differences in survival except poorer survival for Black patients than White patients in the group of other histologic types. Patients with chemotherapy and radiation treatment generally had improved survival whereas patients with squamous cell carcinoma who received chemotherapy had shorter survival than those without. ConclusionSurvival generally did not differ between racial groups, which may be related to equal healthcare access despite racial background. Further studies are warranted to better understand how survival in the MHS compares with that in the general U.S. population. 相似文献
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