893 research outputs found

    Associations Between Climate, Latitude, Fertility and the Decline of the US Sex Ratio at Birth

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    The US sex ratio at birth (SRB) has declined since 1970, while ambient temperatures have been increasing. This study examines the temporal and spatial variation of the US SRB from 1979–2002 in association with fertility rates and climate variables. Approximately 62.8 million birth records from the National Center for Health Statistics were linked to monthly climate division data and county level socioeconomic variables to evaluate the association of SRB and environmental conditions at or near the time of conception. Seasonal variation in US SRB is detectable in time series analysis, and is somewhat in phase with variation in fertility. Logistic regression analysis shows that temperature in the month before conception is significantly positively correlated with the likelihood of a male birth when birth order, maternal age, maternal education, plurality, gestation length, race, and Hispanic origin are controlled. This association was significant in models that include all births from 1979–1988, non-Hispanic white births from 1979–1988, and all births in US large counties from 1979–2002. Geographic nonstationarity of US SRB was found in smoothed rate climate division maps for 1979–1988, with higher SRB in latitudes below 40 degrees N, especially in the southeastern US. However, both the overall rates of summer conception and the likelihood of summer male conception are reduced in lower latitudes relative to higher ones. A logistic regression model was also fit using only non-Hispanic births from US large counties from 1989–2002. In addition to a significant positive association of sex ratio and temperature in the month before conception, deviation from normal monthly temperature during the month of conception, compared to the 1971–2000 baseline temperature, is significantly associated with sex ratio variation. In this population, fewer males were conceived when temperature extremes were significantly above normal; more males were conceived when temperatures were significantly below normal. In both high and low latitude zones over this period, the peak of male conceptions shifted to earlier in the year. Variation in SRB is potentially a sentinel health event and this research suggests that the association between temperature and SRB should be integral to any study of SRB variation across large geographic areas or long time periods

    Toward a Geography of Hormones: The Human Sex Ratio at Birth in the United States 1970-1995

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    It has been hypothesized that humans may exert facultative, adaptive control over their sex of their offspring through the action of the endocrine system. No conclusive evidence of this has been found, although varying hormonal levels in parents at the time of conception may partly influence the sex of the child (James 1986, 1987b, 1999). A decline in the human sex ratio at birth (SRB) observed in the U.S. and some other countries has been attributed by some investigators to widespread environmental exposure to endocrine disrupting chemicals. The many factors hypothesized to influence the SRB make testing this attribution difficult, but one suggestion has been to explore the geographic and temporal pattern of SRB to determine if a sentinel health event signaled by abnormal SRB is present (Davis et al. 1998). This thesis explores the possibilities of geographic analysis of SRB at various scales, focusing on the local geographic scale of the U.S. county to determine whether patterns of explainable variation exist. It tests the basic geographic-patterning assumption, the hypothesis that hormonal mediated influences such as local socioeconomic conditions, adult reproductive sex ratio, urban versus farm environment, and racial composition may influence the SRB, and looks for posited geographic patterning that might be indicative of hormonally active agents working in the human environment. This set of hypotheses is tested in univariate and multivariate logistic regression models combining complete U.S. individual birth record datasets for 1970, 1980 and 1990 with selected U.S. Census county-level statistics that were chosen to represent hypothesized socio-environmental, hormonally mediated influences. Separate models were constructed for white and black births, and variables of birth order, plurality, and seasons of birth were included in multivariate models to control for these confounding individual influences on the SRB. Results show that geographic patterning is strongly evident at the county level and this approach in general works well to elucidate the influence on SRB of these external hormonally medicated factors. SRB in white populations significantly decreased with increases in county urban population proportion in 1980 and 1990 and with increases of the percentage of families living below the poverty line in 1970 and 1990. The change in odds ratio for white male births was barely detectable, however, and was less than that found for individual characteristics such as birth order and plurality. Black population SRB was not as influenced by externally hormonally mediated factors as white SRB, except in 1980. Little clear evidence for the presumed effects of endocrine disruptors was found. The results support further study of externally hormonal mediated influences on the SRB at local geographic scales. In particular, geographic patterning is strongly evident but varies locally in magnitude and sign, and spatially in pattern, between sampling dates. This suggests that not all significant factors are accounted for in this analysis, and that more work needs to be done to weigh the independent influences of individual biological factors and those external factors that might vary with changes in social, economic, and age-distribution conditions. A significant influence of SRB seasonality in the 1970 sample year also suggests that changes in temperature, light, rainfall patterns and other environmental signals that might stimulate hormonal influence of the SRB should be explored

    Evaluation of Policy Scenarios for the 1990 Farm Bill

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    Three alternatives for 1990 farm legislation are examined: (1) a continuation of current legislation; (2) small reductions in producer support levels that are phased in after a two-year delay; and (3) more significant policy reforms that include immediate support reductions for grains and cotton, marketing quotas for dairy products and sugar, and an expanded conservation reserve. Analysis indicates that the alternatives to current policies reduce both government outlays on farm programs and net farm income. The effects on the supply, demand, and prices of most crop and livestock commodities are small. Marketing quotas protect sugar and dairy producer income and allow increased imports without significant budgetary effects, but at considerable cost to consumers

    Treatment utilization and outcomes in elderly patients with locally advanced esophageal carcinoma: A review of the National Cancer Database

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    For elderly patients with locally advanced esophageal cancer, therapeutic approaches and outcomes in a modern cohort are not well characterized. Patients ≥70 years old with clinical stage II and III esophageal cancer diagnosed between 1998 and 2012 were identified from the National Cancer Database and stratified based on treatment type. Variables associated with treatment utilization were evaluated using logistic regression and survival evaluated using Cox proportional hazards analysis. Propensity matching (1:1) was performed to help account for selection bias. A total of 21,593 patients were identified. Median and maximum ages were 77 and 90, respectively. Treatment included palliative therapy (24.3%), chemoradiation (37.1%), trimodality therapy (10.0%), esophagectomy alone (5.6%), or no therapy (12.9%). Age ≥80 (OR 0.73), female gender (OR 0.81), Charlson-Deyo comorbidity score ≥2 (OR 0.82), and high-volume centers (OR 0.83) were associated with a decreased likelihood of palliative therapy versus no treatment. Age ≥80 (OR 0.79) and Clinical Stage III (OR 0.33) were associated with a decreased likelihood, while adenocarcinoma histology (OR 1.33) and nonacademic cancer centers (OR 3.9), an increased likelihood of esophagectomy alone compared to definitive chemoradiation. Age ≥80 (OR 0.15), female gender (OR 0.80), and non-Caucasian race (OR 0.63) were associated with a decreased likelihood, while adenocarcinoma histology (OR 2.10) and high-volume centers (OR 2.34), an increased likelihood of trimodality therapy compared to definitive chemoradiation. Each treatment type demonstrated improved survival compared to no therapy: palliative treatment (HR 0.49) to trimodality therapy (HR 0.25) with significance between all groups. Any therapy, including palliative care, was associated with improved survival; however, subsets of elderly patients with locally advanced esophageal cancer are less likely to receive aggressive therapy. Care should be taken to not unnecessarily deprive these individuals of treatment that may improve survival

    FAPRI U.S. Agricultural Sector Elasticities, Volume I: Crops

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    This report presents estimates of supply, demand, and price transmission elasticities for the U.S. crops sector. The estimates are derived from the U.S. crops model maintained by the Food and Agricultural Policy Research Institute (FAPRI) and are prepared in accordance with procedures stipulated by the Organization for Economic Cooperation and Development (OECD). The first section of this report provides a general overview and describes the procedures used to perform the elasticity calculations. Each succeeding section provides general information about the elasticity estimates for a particular activity. Specific attention is given to those results that may not be intuitively clear and, in particular, to the elasticities that depend on the interaction of two or more equations in the FAPRI modeling system

    FAPRI U.S. Agricultural Sector Elasticities, Volume II: Livestock, Poultry, and Dairy

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    This report presents estimates of supply, demand, and price transmission elasticities for the U.S. livestock, poultry, and dairy sectors. The estimates are derived from models maintained by the Food and Agricultural Policy Research Institute (FAPRI) and are prepared in accordance with procedures stipulated by the Organization for Economic Cooperation and Development (OECD)

    Acoustic Energy and Momentum in a Moving Medium

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    By exploiting the mathematical analogy between the propagation of sound in a non-homogeneous potential flow and the propagation of a scalar field in a background gravitational field, various wave ``energy'' and wave ``momentum'' conservation laws are established in a systematic manner. In particular the acoustic energy conservation law due to Blokhintsev appears as the result of the conservation of a mixed co- and contravariant energy-momentum tensor, while the exchange of relative energy between the wave and the mean flow mediated by the radiation stress tensor, first noted by Longuet-Higgins and Stewart in the context of ocean waves, appears as the covariant conservation of the doubly contravariant form of the same energy-momentum tensor.Comment: 25 Pages, Late

    Deep and Comparative Transcriptome Analysis of Rice Plants Infested by the Beet Armyworm (\u3ci\u3eSpodoptera exigua\u3c/i\u3e) and Water Weevil (\u3ci\u3eLissorhoptrus oryzophilus\u3c/i\u3e)

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    The beet armyworm (Spodoptera exigua) and the rice water weevil (Lissorhoptrus oryzophilus) are two important insect pests in rice production. To identify insect-responsive genes in rice, we performed a deep transcriptome analysis of Nipponbare rice leaves infested with both beet armyworm and water weevil using massively parallel signature sequencing (MPSS). Many antisense, alternative, and novel transcripts were commonly and specifically induced and suppressed in the infested tissue. Key genes involved in the defense metabolic pathways such as salicylic acid and jasmonic acid biosynthesis pathways were up-regulated in the infested leaves. To validate theMPSS results, we analyzed the transcriptome of the rice leaves infested with water weevils using Solexa’s sequencing-bysynthesis (SBS) method. The MPSS and SBS data were highly correlated (Pearson’s correlation coefficient=0.85), and 83% of genes had similar gene expression in both libraries. Our comprehensive and in-depth survey of the insect-infested libraries provides a rich genomic resource for further analyzing the function of key regulatory genes involved in insect resistance in rice. Supplementary files are attached below

    Subcutaneous Metastatic Adenocarcinoma: An Unusual Presentation of Colon Cancer – Case Report and Literature Review

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    Subcutaneous metastasis from a visceral malignancy is rare with an incidence of 5.3%. Skin involvement as the presenting sign of a silent internal malignancy is an even rarer event occurring in approximately 0.8%. We report a case of a patient who presented to her dermatologist complaining of rapidly developing subcutaneous nodules which subsequently proved to be metastatic colon cancer, and we provide a review of the literature
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