Vibrational properties of disordered mono- and bilayers of physisorbed sulfur hexafluoride on Au(111).

We have examined the low-energy single-phonon vibrations of disordered mono- and bilayers of sulfur hexafluoride physisorbed on Au(111) with inelastic helium atom scattering. At monolayer coverages, SF6 exhibits a dispersionless Einstein mode at 3.6 +/- 0.4 meV. We observed two distinct overtones of this vibration as both creation and annihilation events at 7.1 +/- 0.7 meV and 10.9 +/- 1.4 meV, respectively. The overtones are harmonic multiples of the fundamental Einstein oscillation. Bilayers of SF6 exhibit a softer fundamental vibration with an excitation energy of 3.3 +/- 0.3 meV. This softening, due to the weaker SF6 binding, also results in reduced overtone energies of 6.6 +/- 0.7 meV and 9.8 +/- 0.6 meV. The disordered bilayer does not exhibit dispersion, indicating that the molecules are still behaving like Einstein oscillators and not beginning to act as bulk crystalline SF6. The results have improved our understanding of the adsorbate-substrate and interadsorbate interactions which govern the properties of this model molecular physisorption system.

Surface vibrations in alkanethiol self-assembled monolayers of varying chain length.

The effect of chain length on the low-energy vibrations of alkanethiol striped phase self-assembled monolayers on Au(111) was studied. We have examined the low-energy vibrational structure of well-ordered, low-density 1-decanethiol (C10), 1-octanethiol (C8), and 1-hexanethiol (C6) to further understand the interaction between adsorbate and substrate. Dispersionless Einstein mode phonons, polarized perpendicularly to the surface, were observed for the striped phases of C10, C8, and C6 at 8.0, 7.3, and 7.3 meV, respectively. An overtone at 12.3 meV was also observed for C6/Au(111). These results, in concert with molecular dynamics simulations, indicate that the forces between the adsorbate and substrate can be described using simple van der Waals forces between the hydrocarbon chains and the Au substrate with the sulfur chemisorbed in the threefold hollow site.

Annual summary of vital statistics: 2000.

The birth rate in 2000 (preliminary data) was 14.8 births per 1000 population, an increase of 2% from 1999 (14.5). The fertility rate, births per 1000 women aged 15 to 44 years, increased 3% to 67.6 in 2000, compared with 65.9 in 1999. The 2000 increases in births and the fertility rate were the third consecutive yearly increases, the largest in many years, halting the steady decline in the number of births and fertility rates in the 1990s. Fertility rates for total white, non-Hispanic white, black, and Native American women each increased about 2% in 2000. The fertility rate for black women, which declined 19% from 1990 to 1996, has changed little since 1996. The rate for Hispanic women rose 4% in 2000 to reach the highest level since 1993. Birth rates for women 30 years or older continued to increase. The proportion of births to unmarried women remained about the same at one third, but the number of births rose 3%. The birth rate for teen mothers declined again for the ninth consecutive year. The use of timely prenatal care (83.2%) remained unchanged in 2000, and was essentially unchanged for non-Hispanic white (88.5%), black (74.2%), and Hispanic (74.4%) mothers. The number and rate of multiple births continued their dramatic rise, but all of the increase was confined to twins; for the first time in more than a decade, the number of triplet and higher-order multiple births declined (4%) between 1998 and 1999 (multiple birth information is not available in preliminary 2000 data). The overall increases in multiple births account, in part, for the lack of improvement in the percentage of low birth weight (LBW) births. LBW remained at 7.6% in 2000. The infant mortality rate (IMR) dropped to 6.9 per 1000 live births (preliminary data) in 2000 (the rate was 7.1 in 1999). The ratio of the IMR among black infants to that for white infants was 2.5 in 2000, the same as in 1999. Racial differences in infant mortality remain a major public health concern. The role of low birth weight in infant mortality remains a major issue. Among all of the states, Utah and Maine had the lowest IMRs. State-by-state differences in IMR reflect racial composition, the percentage LBW, and birth weight-specific neonatal mortality rates for each state. The United States continues to rank poorly in international comparisons of infant mortality. Expectation of life at birth reached a record high of 76.9 years for all gender and race groups combined. Death rates in the United States continue to decline. The age-adjusted death rate for suicide declined 4% between 1999 and 2000; homicide declined 7%. Death rates for children 19 years of age or less declined for 3 of the 5 leading causes in 2000; cancer and suicide levels did not change for children as a group. A large proportion of childhood deaths, however, continue to occur as a result of preventable injuries.

Teenage childbearing in the United States, 1960-1997.

Teenage childbearing in the United States has declined significantly in the 1990s. Still the U.S. teen birth rate is higher than in other developed countries; in 1997 it was 52.3 births per 1000 women aged 15 to 19. A steep rise in teen birth rates in the late 1980s generated a great deal of public concern and a variety of initiatives targeted to reducing teen births. Data from the National Center for Health Statistics' National Vital Statistics System are used to review and describe trends and variations in births and birth rates for teenagers for the period 1960-1997. Teen birth rates were much higher in the early 1960s than at present; in fact, rates for 18- to 19-year-olds were double what they are currently. In the 1990s, birth rates for teenagers dropped for younger and older teenagers, with greater declines recorded for younger teens. While rates have fallen in all population groups, the greatest declines have been experienced by black teenagers, whose rates have dropped 24% on average. %Trends in teen births and birth rates since 1960 have been affected by a variety of factors. These include wide swings in the number of female teenagers, substantial declines in marriage among older teens, falling birth rates for married teens concurrent with rapidly rising birth rates for unmarried teens, and sharp increases in sexual activity among teens that have abated only recently, according to the National Center for Health Statistics' National Survey of Family Growth. This review article also tracks changes in contraceptive practice and abortion rates.

Annual summary of vital statistics: trends in the health of Americans during the 20th century.

The overall improvement in the health of Americans over the 20th century is best exemplified by dramatic changes in 2 trends: 1) the age-adjusted death rate declined by about 74%, while 2) life expectancy increased 56%. Leading causes of death shifted from infectious to chronic diseases. In 1900, infectious respiratory diseases accounted for nearly a quarter of all deaths. In 1998, the 10 leading causes of death in the United States were, respectively, heart disease and cancer followed by stroke, chronic obstructive pulmonary disease, accidents (unintentional injuries), pneumonia and influenza, diabetes, suicide, kidney diseases, and chronic liver disease and cirrhosis. Together these leading causes accounted for 84% of all deaths. The size and composition of the American population is fundamentally affected by the fertility rate and the number of births. From the beginning of the century there was a steady decline in the fertility rate to a low point in 1936. The postwar baby boom peaked in 1957, when 123 of every 1000 women aged 15 to 44 years gave birth. Thereafter, fertility rates began a steady decline. Trends in the number of births parallel the trends in the fertility rate. Beginning in 1936 and continuing to 1956, there was precipitous decline in maternal mortality from 582 deaths per 100 000 live births in 1935 to 40 in 1956. Since 1950 the maternal mortality ratio dropped by 90% to 7.1 in 1998. The infant mortality rate has shown an exponential decline during the 20th century. In 1915, approximately 100 white infants per 1000 live births died in the first year of life; the rate for black infants was almost twice as high. In 1998, the infant mortality rate was 7.2 overall, 6.0 for white infants, and 14.3 for black infants. For children older than 1 year of age, the overall decline in mortality during the 20th century has been spectacular. In 1900, >3 in 100 children died between their first and 20th birthday; today, <2 in 1000 die. At the beginning of the 20th century, the leading causes of child mortality were infectious diseases, including diarrheal diseases, diphtheria, measles, pneumonia and influenza, scarlet fever, tuberculosis, typhoid and paratyphoid fevers, and whooping cough. Between 1900 and 1998, the percentage of child deaths attributable to infectious diseases declined from 61.6% to 2%. Accidents accounted for 6.3% of child deaths in 1900, but 43.9% in 1998. Between 1900 and 1998, the death rate from accidents, now usually called unintentional injuries, declined two-thirds, from 47. 5 to 15.9 deaths per 100 000. The child dependency ratio far exceeded the elderly dependency ratio during most of the 20th century, particularly during the first 70 years. The elderly ratio has gained incrementally since then and the large increase expected beginning in 2010 indicates that the difference in the 2 ratios will become considerably less by 2030. The challenge for the 21st century is how to balance the needs of children with the growing demands for a large aging population of elderly persons.

Sudden sensorineural hearing loss.

Approximately 4000 new cases of sudden hearing loss (SHL) occur annually in the United States, and 15,000 annually worldwide, accounting for approximately 1% of all cases of SHL. Although prevalence studies do not necessarily distinguish between idiopathic and acquired SHL, most cases of spontaneous SHL have no identifiable cause. In this article, the authors assess the cause, history, diagnosis, and treatment of SHL.

What is assessment?

The Institute of Medicine's report on The Future of Public Health identified assessment, policy development, and assurance as core functions of public health. Assessment is a process whereby public health agencies identify health problems, identify health resources and evaluate their effectiveness, and present the results of these analyses to decision makers. These efforts are carried out through a division of labor among local, state, and federal agencies. The responsibility for assessment extends to all areas of the country and to every area of public health: from infectious diseases to chronic conditions, from behavioral risks to environmental hazards, and from motor vehicles to hand guns.

DATA2000: CDC WONDER information system linking Healthy People 2000 objectives to data sets.

To monitor progress on the Healthy People (HP) 2000 objectives, planners and researchers will need information on relevant data sources. DATA2000 is a project designed to identify these data and link them with objectives and to develop a computerized information system providing access to this information. Sources of information on objectives and data included Healthy People 2000, catalogs and data bases of data sets, and the HP 2000 Steering Committee. We created an "assessment" of the utility of the data set for the particular objective. A Centers for Disease Control (CDC) WONDER-based information system was developed (using methods previously described). We identified 204 data sets and created 408 assessments. All but one of the objectives were paired with corresponding data. Over half the data come from CDC. The CDC WONDER-based information system crosslinks the objectives, data sets, and assessments and provides 5-10 pages of information about each. Understanding the contribution of prevention will be critical in planning reforms of the health care system. DATA2000 can be an important resource in this process.

The 1989 revisions of the US Standard Certificates of Live Birth and Death and the US Standard Report of Fetal Death.

The US Standard Certificates and Reports are models used by state vital statistics offices to develop documents for the collection of data about vital events. The 1989 revisions incorporate some major modifications to previous versions. Both the Standard Certificate of Live Birth and the Standard Report of Fetal Death utilize a checkbox format to elicit information on medical and other risk factors affecting the pregnancy, complications of labor and/or delivery, obstetric procedures, method of delivery, congenital anomalies, and abnormal conditions of the newborn. Revisions to the Standard Certificate of Death include modifications to the medical certification section and the addition of decedent's educational attainment. Items requesting information about Hispanic origin are added to all of these documents. The rationale behind these changes and their intended use are discussed.

Experiences with linked birth and infant death certificates from the NIMS project.

The National Infant Mortality Surveillance (NIMS) project aggregated data provided by 53 vital statistics reporting areas--50 States, New York City, the District of Columbia, and Puerto Rico (subsequently called States)--from their files of linked birth and death certificates and compared individual States' total infant mortality experiences for the 1980 birth cohort by age at death, race, birth weight, and plurality. Therefore, it was essential to achieve maximum uniformity among the separate data sets and to specify when this uniformity could not be obtained. In working with these multiple sources, we identified five key issues that relate to data from linked birth and death certificates: Variations in definitions of variables are often embedded in data that have been gathered from several independent sources. (For NIMS, the sources were 53 reporting areas and the National Center for Health Statistics.) Variations in States' linking procedures--these are based on an individual State's primary purpose for linking the data--affect the completeness and comparability of the 1980 resident birth cohorts used for NIMS. Variations in the recording of some pregnancy outcomes as fetal deaths or live births are known to be a problem in vital statistics data that particularly affects data for events among infants weighing less than 500 g at birth. Ambiguities occur frequently in unknowns or zero values. For NIMS this effect was most pronounced for the pregnancy history variables. Examination of the values reported for unknown or zero categories helps in uncovering problems with and improving quality of data. (e) Analysis from a new perspective may reveal unexpected data problems. These problems tend to surface only during a reexamination of underlying data that is prompted by unusual findings.Continued alertness to these issues may improve further the quality of data in files of linked birth and death certificates and assure the integrity of analysis based on these data.

PIP: The authors analyze the quality of data in the files of linked birth and death certificates from the U.S. National Infant Mortality Surveillance (NIMS) project. The project compared individual states' total infant mortality experiences for the 1980 cohort. Uniformity among the separate data sets is considered essential. Variations in definitions, variations in states' linking procedures, variations in the recording of some pregnancy outcomes, ambiguous treatment of unknowns or zero values, and unexpected data problems are discussed