Recent Plateau Research Articles

Phylogeography of the genusDasiphora(Rosaceae) in the Qinghai-Tibetan Plateau: divergence blurred by expansion

Plateau uprisings and climatic oscillations are considered to have caused extensive allopatric divergences that account for the rich species diversity of the Qinghai-Tibetan Plateau (QTP). However, secondary contact during range shifts in the Quaternary glacial cycles or inter-uplift stages may have restored the gene flow between species and so counteracted these divergences, particularly in rapidly-adapting dominant elements. We tested this hypothesis by determining the phylogeographical history of Dasiphora (Rosaceae), a genus of two species that are widely distributed on the QTP and co-exist in numerous localities. We sequenced two chloroplast DNA fragments (rbcL, trnT-L) for 559 individuals from 87 populations. Bayesian methods were used to identify phylogenetic relationships and to estimate divergence times. Demographic histories were inferred using neutrality tests, mismatch distribution analysis, and coalescent simulation. A total of 112 haplotypes that clustered into three major groups were identified. The formation of these groups and their subgroups was dated to between the Pliocene and the late Pleistocene. In addition, we found that some groups underwent multiple extensive expansions. Species-specific haplotypes were identified for each species, although these haplotypes phylogenetically intermixed. These results suggest that recent plateau uplifts and climatic oscillations might have caused the deep divergences observed within this genus. However, later range expansions probably blurred these divergences and possible species boundaries. Our results shed new light on the complex evolutionary history of the QTP alpine plants. (c) 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 111, 777-788.

Population Assessment of Future Trajectories in Coronary Heart Disease Mortality

BackgroundCoronary heart disease (CHD) mortality rates have been decreasing in Iceland since the 1980s, largely reflecting improvements in cardiovascular risk factors. The purpose of this study was to predict future CHD mortality in Iceland based on potential risk factor trends.Methods and findingsThe previously validated IMPACT model was used to predict changes in CHD mortality between 2010 and 2040 among the projected population of Iceland aged 25–74. Calculations were based on combining: i) data on population numbers and projections (Statistics Iceland), ii) population risk factor levels and projections (Refine Reykjavik study), and iii) effectiveness of specific risk factor reductions (published meta-analyses). Projections for three contrasting scenarios were compared: 1) If the historical risk factor trends of past 30 years were to continue, the declining death rates of past decades would level off, reflecting population ageing. 2) If recent trends in risk factors (past 5 years) continue, this would result in a death rate increasing from 49 to 70 per 100,000. This would reflect a recent plateau in previously falling cholesterol levels and recent rapid increases in obesity and diabetes prevalence. 3) Assuming that in 2040 the entire population enjoys optimal risk factor levels observed in low risk cohorts, this would prevent almost all premature CHD deaths before 2040.ConclusionsThe potential increase in CHD deaths with recent trends in risk factor levels is alarming both for Iceland and probably for comparable Western populations. However, our results show considerable room for reducing CHD mortality. Achieving the best case scenario could eradicate premature CHD deaths by 2040. Public health policy interventions based on these predictions may provide a cost effective means of reducing CHD mortality in the future.

Trends in Food and Beverage Sources among US Children and Adolescents: 1989-2010

Despite the historical rise and recent plateau of child overweight and obesity, levels remain exceedingly high. To understand these trends and identify targets for intervention it is important to examine concomitant trends in children's diets. The objective of our analysis was to describe 21-year trends in total energy intake and the major food and beverage sources of energy among 2- to 18-year-olds in the United States. Six nationally representative surveys were examined in 2012, the Continuing Survey of Food Intakes by Individuals (1989-1991 and 1994-1996, 1998) and the National Health and Nutrition Examination Survey (2003-2004, 2005-2006, 2007-2008, and 2009-2010). Total energy intake among US children and adolescents rose considerably from 1989 to 2004, and subsequently declined through 2010. Seven sources were consistently major contributors across all time points: sugar-sweetened beverages, pizza, full-fat milk, grain-based desserts, breads, pasta dishes, and savory snacks. Intakes of full-fat milk, meats and processed meat products, ready-to-eat cereals, burgers, fried potatoes, fruit juice, and vegetables decreased from 1989-2010 whereas intakes of nonfat milk, poultry, sweet snacks and candies, and tortilla- and corn-based dishes increased linearly over the 21-year period. Significant nonlinear time trends were observed with recent decreases in intakes of sugar-sweetened beverages, pizza, pasta dishes, breads and rolls, and savory snacks and recent increases in intake of fruit. Energy intakes of US children began to decline in 2003-2004 and continued to decline through 2009-2010. However, among preschool children (aged 2 to 5 years) and children from low-income families, total energy intakes in 2009-2010 still remained significantly higher than in 1989-1991.

Espaciamiento de los nacimientos y el descenso de la fecundidad en Costa Rica

Este trabajo utiliza datos de las Encuestas Comparativas de Fecundidad de América Latina, así como de la Encuesta Mundial de Fecundidad para estudiar las tendencias y diferenciales en el espaciamiento de los nacimientos entre las mujeres alguna vez casadas en Costa Rica durante el período 1945-1974. Una buena parte de la atención se pone en el ritmo de la fecundidad en las etapas umbral, temprana y tardía de la disminución de la fecundidad que este país experimentó durante los años sesenta y principios de los setenta. Los resultados muestran bastante similitud en el tempo de la reproducción en los diferentes niveles paridez y áreas geográficas. Sin embargo, un análisis de las variables del entorno que afectan espaciamiento de los nacimientos muestra diferencias entre las zonas urbanas y rurales. Por último, se postula que el reciente estancamiento en las tasas de período puede ser una consecuencia de los cambios en el tempo de construcción de la familia, con mujeres de baja paridez que postergan los nacimientos, lo que contrarresta las tendencias de descenso que generan las mujeres de mayor paridez quienes aún pueden estar restringiendo su reproducción.

System Science Models and National Data Projected Future Trends and Racial/Ethnic Disparities in Childhood Obesity in the US

BackgroundAlthough the obesity prevalence seems to level off in young children in the US recently, the racial/ethnic disparities remain substantial. The non‐linear dynamic complexity in the increase of childhood obesity rates over time is not well studied.ObjectivesTo forecast future trends and disparities in childhood obesity in US till 2030.MethodsWe fit system dynamics models to simulate changes in obesity rates in children (aged 2–19 y) using the 1999–2010 National Health and Nutrition Examination Survey (NHANES) data and forecasted the trends till 2030.ResultsOur models reproduced the leveling off in the past decade. Incorporating the projection of demographic composition changes in US population, our simulations suggest that by 2030 27% of boys and 23% of girls will be obese. The disparities gap will increase, and by 2030, 38%, 32%, and 18% of Mexican‐American, Non‐Hispanic black, and non‐Hispanic white boys will be obese, respectively. In girls, the figures are 26%, 40% and 17%, respectively.ConclusionsOur simulations demonstrate the recent plateau is temporary, and current efforts are not sufficient to stop the increase. Specially more effort need to target minorities.Grant Funding Source: NIH/NICHD (U54 HD070725‐01,1R01HD064685–01A1) and NIDDK (R01DK81335–01A1)

Computational advances in gravitational microlensing: A comparison of CPU, GPU, and parallel, large data codes

To assess how future progress in gravitational microlensing computation at high optical depth will rely on both hardware and software solutions, we compare a direct inverse ray-shooting code implemented on a graphics processing unit (GPU) with both a widely-used hierarchical tree code on a single-core CPU, and a recent implementation of a parallel tree code suitable for a CPU-based cluster supercomputer. We examine the accuracy of the tree codes through comparison with a direct code over a much wider range of parameter space than has been feasible before. We demonstrate that all three codes present comparable accuracy, and choice of approach depends on considerations relating to the scale and nature of the microlensing problem under investigation. On current hardware, there is little difference in the processing speed of the single-core CPU tree code and the GPU direct code, however the recent plateau in single-core CPU speeds means the existing tree code is no longer able to take advantage of Moore’s law-like increases in processing speed. Instead, we anticipate a rapid increase in GPU capabilities in the next few years, which is advantageous to the direct code. We suggest that progress in other areas of astrophysical computation may benefit from a transition to GPUs through the use of “brute force” algorithms, rather than attempting to port the current best solution directly to a GPU language – for certain classes of problems, the simple implementation on GPUs may already be no worse than an optimised single-core CPU version.

Abstract A129: Declining incidence of breast cancer since 2002 in the United States: How much is explained by the decrease in postmenopausal hormone use?

Abstract The striking decline in breast cancer incidence since 2002 in the United States has been widely attributed to discontinuation of postmenopausal hormone use following the results of the Women's Health Initiative (WHI) randomized trial. However, very little analysis has been conducted to quantify the contribution of cessation of hormone use to the observed decline in breast cancer incidence. We used literature-based estimates of the change in the prevalence of hormone use and the relative risk associated with hormone use to estimate the impact of cessation of hormone use on the observed decline in breast cancer incidence between 2002 and 2003 among women aged 40–79 years old. For the base case of a 46% decline in hormone use and a relative risk for current use of 1.5, we estimate that 42% of the decline in incidence was attributable to cessation of hormone use. By exploring a range of parameter values we found that high, unlikely values of the relative risk (i.e., ≥2.25) and/or the percent decline in hormone use (i.e., ≥75%) would be required to account for 100% of the observed decline in breast cancer incidence. We conclude that cessation of postmenopausal hormone use following the announcement of the results of the WHI is unlikely to account for more than half of the observed decline in breast cancer incidence among women aged 40–79 years old. The potential contributions of other factors should be examined in future studies, especially the role of the recent plateau in screening utilization. Citation Information: Cancer Prev Res 2010;3(1 Suppl):A129.

Trends in incidence of childhood cancer in Australia, 1983–2006

Background:There are few population-based childhood cancer registries in the world containing stage and treatment data.Methods:Data from the population-based Australian Paediatric Cancer Registry were used to calculate incidence rates during the most recent 10-year period (1997–2006) and trends in incidence between 1983 and 2006 for the 12 major diagnostic groups of the International Classification of Childhood Cancer.Results:In the period 1997–2006, there were 6184 childhood cancer (at 0–14 years) cases in Australia (157 cases per million children). The commonest cancers were leukaemia (34%), that of the central nervous system (23%) and lymphomas (10%), with incidence the highest at 0–4 years (223 cases per million). Trend analyses showed that incidence among boys for all cancers combined increased by 1.6% per year from 1983 to 1994 but have remained stable since. Incidence rates for girls consistently increased by 0.9% per year. Since 1983, there have been significant increases among boys and girls for leukaemia, and hepatic and germ-cell tumours, whereas for boys, incidence of neuroblastomas and malignant epithelial tumours has recently decreased. For all cancers and for both sexes combined, there was a consistent increase (+0.7% per year, 1983–2006) at age 0–4 years, a slight non-significant increase at 5–9 years, and at 10–14 years, an initial increase (2.7% per year, 1983–1996) followed by a slight non-significant decrease.Conclusion:Although there is some evidence of a recent plateau in cancer incidence rates in Australia for boys and older children, interpretation is difficult without a better understanding of what underlies the changes reported.

House Committee Examines Key MH Concerns

Back to table of contents Previous article Next article Government NewsFull AccessHouse Committee Examines Key MH ConcernsRich DalyRich DalySearch for more papers by this authorPublished Online:4 Aug 2006https://doi.org/10.1176/pn.41.15.0004In its first hearing to look at mental illnesses as biologically based diseases, a congressional panel with oversight of federal mental health programs highlighted multiple areas in which federal support has fallen short of the rhetoric.The House Energy and Commerce Subcommittee on Health held a hearing on June 28 to discuss mental illness, its costs, and the state of research on the issue. Committee leaders said the hearing aimed to increase awareness of psychiatric disorders, rather than to encourage the passage of mental health parity legislation, but some committee members pressed the issue anyway.“The president in 2002 said he favored ending discriminatory insurance. We should join him in his forward thinking,” said Rep. Anna Eschoo (D-Calif.). “There seems to be an attitude in Congress that we can take some baby steps, but we can't take the last full step that we need: parity.”Subcommittee Chair Rep. Nathan Deal (R-Ga.) said passage of parity legislation (HR 1402)—which has 227 cosponsors—is less likely to pass in the House of Representatives than is increased mental health funding.Supporters of the parity legislation highlighted its potential economic benefits for the nation, including a reduction in the estimated $180 billion in lost productivity every year related to mental illness.Opponents of the measure focused on concerns that mental health parity would “run up the cost of health insurance for everyone,” said Rep. John Shadegg (R-Ariz.). This ran counter to arguments made by parity supporters, who highlighted a 2001 report by the federal Office of Personnel Management that found that added mental health benefits for federal employees increased costs by just 1.3 percent; other research has arrived at similar conclusions.Shadegg said health care costs for employers are already accelerating so fast that U.S. companies are on the verge of becoming uncompetitive in a global marketplace where many overseas businesses do not bother with such coverage.Rep. Sherrod Brown (D-Ohio) said the flaw in thinking that parity would lead to expensive coverage of a “popular” service is based on the mistaken idea that many people use mental health care recreationally.Besides parity legislation, committee members and witnesses concentrated on the recent plateau that federal mental health research funding has reached in the Fiscal 2007 budget.“It is unacceptable that this Congress, which has doubled the research funding of the NIH [National Institutes of Health] in the past, has allowed it to now flatline,” said Rep. Tammy Baldwin (D-Wis.), about such plans as President Bush's proposed budget that holds funding for the NIH to the 2006 level of $28.6 billion.Thomas Insel, M.D., director of the National Institute of Mental Health, did not directly press for more funding but described ongoing research into new targets for treatment and ways to use current treatments more effectively.“We are now on the verge of significant advances that will move us closer to predictive, preventive, and personalized mental health care grounded in research,” Insel said.Rep. Tim Murphy (R-Pa.), a psychologist, also highlighted financial concerns when he noted that untreated mental illness can increase the risk for other ailments such as heart disease and doubles the cost of health care.“Without integrating the cost of the body with the care of the brain, our current system is wasting billions of dollars,” he stressed.Murphy cited research that found that when depression management was included in employee health plans, productivity increased more than 6 percent, and absenteeism declined 28 percent, while saving $2,601 for each affected employee. He also cited research that found that workers with depression who receive treatment incur $882 less in medical costs each year on average.Rep. Sue Myrick (R-N.C.), who said her now-adult granddaughter was diagnosed with bipolar disorder at 13, helped organize the hearing. She and others said society was ready to accept mental illness without stigma—the way it did cancer 20 or 30 years ago.“People who had cancer 20 years ago wouldn't tell anyone because they were scared they would look weak or might even lose their job,” said Myrick, who survived breast cancer. “Today, people with brain disease face the same problems in society.”Among the most passionate testimony was that dealing with mental illness's contribution to many of the nearly 30,000 suicides each year in this country. Kay Redfield Jamison, Ph.D., a professor of psychiatry at Johns Hopkins School of Medicine who suffers from bipolar disorder, asked for research funding commensurate with the pain and death mental illness causes.“Mostly, I have been impressed by how little value our society puts on saving the lives of those who are in such despair as to want to end them,” Jamison said.The text of HR 1402 is posted at<http://frwebgate.access.gpo.gov/cgi-bin/getdoc.cgi?dbname=109_cong_bills&docid=f:h1402ih.txt.pdf>.▪ ISSUES NewArchived

The Trajectory of the United States in the World-System: A Quantitative Reflection

Using improved estimates of world and country GDPs, population, and GDP per capita published by Angus Maddison (2001), we report findings of a quantitative study of the trajectory of the United States in world historical perspective. We compare the U.S. economic hegemony of the twentieth century with the seventeenth-century Dutch hegemony and the British hegemony of the nineteenth century. We also track the trajectories of challengers and discuss the future of hegemonic rivalry and global governance. Our findings support the existence of a sequence of hegemonic rises and declines. Despite a recent plateau in the decline of U.S. economic hegemony, we contend that the United States will continue to decline.

RECENT TRENDS IN INCIDENCE RATES FOR SELECTED ALCOHOL-RELATED CANCERS IN THE UNITED STATES

To examine recent trends in incidence rates for cancer types most strongly associated with alcohol use, using data from US cancer registries. Age-standardized annual incidence rates (ASIRs) for squamous cell carcinomas of the oral cavity and pharynx, esophagus and larynx diagnosed in the most recent 10-year period (1992-2001) were examined for geographic areas included in the US National Cancer Institute's Surveillance, Epidemiology and End Results (SEER) program of high-quality cancer registries. For all geographic areas combined, ASIRs for these cancers declined over time, with no evidence for a recent plateau or upturn. This also held true for ASIRs in younger adults (age 20-54 years at diagnosis). For white males, declines in ASIRs occurred in each of the 11 geographic areas, and were statistically significant in nine areas. The declines in ASIRs were consistent with temporal declines in apparent alcohol consumption by state, although the prevalence of binge and heavy drinking in adults increased in some states. Although there was no evidence for a recent plateau in ASIRs, continued surveillance is needed, in view of recent increases in the prevalence of binge and heavy drinking among US adults.

Molecular Excitation at the Nucleus of the QSO I Zw 1

We present results from the most recent Plateau de Bure observation of the 12CO(2-1) line towards the nearby QSO I Zw 1.

Preventive Approach to Poststroke Rehabilitation in Older People

Stroke is the leading cause of adult neurologic-related disability. With the recent plateau in stroke death rates, the steady growth in the elderly population, and the secular trend toward more moderate levels of neurologic impairments, stroke continues to be a major health problem requiring rehabilitation interventions. For those who receive rehabilitation, the prognosis is good: most will walk, the greater percentage will be independent in activities of daily living, and only a small percentage will need institutionalization. Providing rehabilitation interventions that are timely, age-specific, and inclusive of treatment for all domains affected enhances potential recovery for elderly people.

The leveling of divorce in the united states

Is the recent plateau in crude divorce rates due to compositional changes in the married population or to a fundamental change in the long-term trend of rising marital instability? I use refined measures of period divorce rates to show that the leveling of divorce rates appears to be real. Compositional factors do little to explain the end to the more than century-long pattern of rising divorce. Increases in cohabitation also fail to explain the plateau. New theories are needed to explain the determinants of divorce rates at the population level.

Komatiite-Tholeiite and Boninite Series Volcanic Associations of the Abitibi Greenstone Belt: Plume-Protoarc Interaction, and Crustal Growth

Komatiite-tholeiite sequences and boninite series volcanic rocks are spatially associated at several localities along a 300 km strike sector of the late Archaean (2.7 Ga) Abitibi greenstone belt, Canada. Examples include the Kidd volcanic complex (KVC) and volcanic sequences in Tisdale and Whitney Townships near Timmins, Ontario, as well as volcanic sequences near Val d'Or, Quebec. In the field, the different types of flows interdigitate on a scale of 10's to 100's metres. Komatiites include Munro, or Al-undepleted type, and Barberton, or Al-depleted type. Spinifex textured Al-undepleted komatiites at the KVC and Whitney localities, like Munro counterparts, are characterized by near-chondritic A1203/TiO2, Ti/Zr, and Zr/Y ratios. They have (1) near-fiat HREE, (2) variable L R E E depletion (La/Smn 0.4 to 0.8), and (3) small positive Hf anomalies relative to Sm, with Zr/Hf 400 km, whereas Al-undepleted komatiites reflect melt segregation at shallow levels. Mg-, Fe-tholeiites are spatially associated with the komatiites. They have near-flat R E E patterns over a continuous range from 4 to 20x chondritic abundance. Mg#, Cr, and Ni decrease continuously with increasing REE, Th, Nb, Zr, Hf and Y. The most primitive have near-chondritic interelement ratios. This magma series is interpreted to represent dynamic partial melting in the outer envelope of the mantle plume from which the komatiitic liquids were derived. Collectively, the tholeiites have a continuous range from negative to positive anomalies of Nb relative to Th and La, similar to Phanerozoic and Recent ocean plateau basalts and some ocean island basalts (Saunders et al., 1988). Alteration and crustal contamination can be ruled out as the source of the anomalies. The negative anomalies are consistent with recycling of subduction-influenced subarc mantle, or continental crust, into the mantle, and the positive anomalies recycling of ocean crust processed through a subduction zone (Saunders et al., 1988; McDonough, 1991). Consequently, the plume from which the komatiites and tholeiitic basalts were derived was multi-component, as demonstrated from trace element and isotope systematics on Phanerozoic and Recent plume-related basalts (Mahoney et al., 1993). Compositionally, the boninite series flows range from Mg# = 81-45, TiO2 = 0.17-0.41, and Ni = 1020-310 ppm. They are characterized by high A1203 (12-16 wt.%) contents, and A1203/TiO2 (60-84) ratios. In common with Phanerozoic boninites, these flows have negatively fractionated H R E E (Gd/Ybn = 0.4-0.6), Zr/Y (1.4-2.2) less than the primitive mantle value of 2.4, and variably positive Zr and Hf anomalies, where Zr/Hf 53% and Mg# > 60 given by Crawford et al. (1989). Collectively, the boninite series overlap spinifex texatred Al-undepleted komatiites in terms of TiO2 and Zr contents, but are much more aluminous, possess higher A1203/ TiO2 ratios and Sc and Yb contents, but lower Gd/ Ybn and Zr/Y ratios. The boninites are interpreted to have formed in a protoarc from second stage metasomatic enrichment of a mantle source highly

New zircon fission-track ages from New Zealand Quaternary tephra: an interlaboratory experiment and recommendations for the determination of young ages

Fission-track dating, of zircons from five Pleistocene tephra in the Wanganui Basin, North Island, New Zealand, has been carried out independently in two different laboratories. The results from each are statistically identical even though there were some differences in laboratory techniques. The resulting ages confirm recent isothermal plateau fission-track (ITPFT) ages on two of these tephra, but with increased precision. The weighted mean ages (± 1σ) are: Potaka Tephra, 0.97 ± 0.04 Ma (4 determinations); Rewa Pumice, 1.00 ± 0.06 Ma (3 determinations); Mangapipi Ash, 1.26 ± 0.08 Ma (2 determinations); Pakihikura Pumice, 1.66 ± 0.07 Ma (4 determinations); and the Vinegar Hill Tephra, 1.73 ± 0.08 Ma (3 determinations). These new results further constrain the time control in this important Pleistocene section which contains many cyclothems reflecting climatic and tectonic influences. This study illustrates well the pitfalls that can occur when dating such young material using single-crystal techniques. The difficulties of determining when etching is optimal, the presence of detrital grains and their subsequent removal from the data set are described, as well as a recommendation that a minimum of 15 crystals, but optimally at least 20, be counted before calculating the final age. It may also be necessary to plot running means of the single-crystal ages to determine when the final age has been approached.

Mortality trends in a cohort of homosexual men in New York City, 1978-1988.

Trends in mortality related to infection by human immunodeficiency virus type 1 (HIV-1) and to other causes were examined from 1978 to 1988 in a cohort of 8,906 homosexual men who participated in studies of hepatitis B virus infection in the late 1970s in New York City. HIV-related mortality rates increased from 1 per 10,000 person-years in 1980 to 181 per 10,000 person-years in 1986, followed by a plateau from 1986 to 1988. The standardized mortality ratio among white men in the cohort was 3.7 (95% confidence interval (Cl) 3.4-3.9) as compared with white men from across the United States. Higher HIV-related mortality rates were associated with a higher number of sexual partners, a history of gonorrhea and/or syphilis, and serologic markers of infection with hepatitis B virus. After adjustment for demographics and sexual behaviors, the relative risk of mortality for Hispanic men as compared with white men was 1.5 (95% Cl 1.1-1.9). This study illustrates the large excess in mortality among homosexual men over the last decade, with the excess accounted for by deaths from HIV-related diseases. The recent plateau in mortality may be due to the effect of new treatments and/or the decline in new HIV-1 infections among homosexual men. The excess in HIV-related mortality among Hispanic homosexual men was not explained by differences in demographics and factors associated with the sexual transmission of HIV-1.

Southern Patagonian plateau basalts and deformation: Backarc testimony of ridge collisions

The distribution and volume of Tertiary Patagonian plateau basalts and the evolution of the Patagonian fold and thrust belt between 46° and 49°S appear to be closely tied with ridge-trench interactions along the continental margin to the west. Eocene plateau basalts south of 43°S are associated with a gap in the Eocene arc and can be related to a proposed collision of the Aluk-Farallon ridge against the trench at this time. Eruptions of Late Miocene to Recent plateau basalts between 46° and 49°S can be related to time-transgressive slab windows in the underlying mantle generated by the collision of segments of the Chile ridge at 10–14 Ma and 6 Ma. The principal deformation in the Patagonian fold and thrust belt predates the eruption of the basalts and also appears to be related with Late Miocene ridge collision. Comparison of plateau basalts related to the collision of the three distinct ridge segments suggests that the volume of basalt erupted increases with the length of the collided ridge segment. Almost all Eocene to Recent plateau basalts between 46° and 49°S have OIB-like (ocean island basalt) trace element signatures showing that the mantle source region changed little with time. Plateau basalts with more arc-like signatures appear to be contaminated by continental crust. Relative melting percentages inferred from the trace element chemistry of the plateau basalts correlate with volumes of erupted basalt implying spatial and temporal changes in temperatures in the mantle source that can be correlated with slab windows.

Epidemiologic aspects of control of penicillinase-producing Neisseria gonorrhoeae.

Although first identified in 1976, penicillinase-producing Neisseria gonorrhoeae (PPNG) began to have significant epidemiologic impact in the United States only after 1980. The epidemic curve has been marked by a series of successive sigmoidal increases, the result of staggered epidemic activity in Los Angeles, California, New York, New York, and Miami. The most recent increase and current plateau has led to a provisional total of 16,608 cases for 1986, with the proportion of PPNG isolates as high as 30% in some communities. The intensity of PPNG transmission appears to parallel that of gonorrhea in general, with high attack rates in central city areas (i.e., among core groups) and with a dimmishing gradient outward from the center. The endemicity of PPNG is related in a general way to the size of the inoculum. A county experiencing seven cases in a month at the time of introduction, for example, has less than a 50% probability of reverting to zero cases during the next 12 months. It would appear that the inoculation of PPNG organisms into a community leads to a "take" when high-level transmitters of gonorrhea are affected. Though current projections suggest as many as 35,000-40,000 cases of PPNG infections by 1991, control programs that focus resources on core-group transmitters of gonorrhea may alter that course.