Delay in Reporting Acquired Immune Deficiency Syndrome (AIDS)

As of March 31, 1987, the U.S. Centers for Disease Control had reported 33,350 cases of acquired immune deficiency syndrome. Yet by that date, physicians had actually diagnosed 42,670 cases. The difference arises from significant delays in the reporting of AIDS cases to public health authorities. An estimated 70% of cases are reported two or more months after diagnosis; about 23% are reported seven or more months later; and about 5% take more than three years to come in. Moreover, the probability distribution of delays has been shifting to the right, with the median delay increasing by 0.6 months since mid-1986. From the data on reported cases and the estimated probability distribution of reporting delays, I reconstruct the actual incidence of AIDS from January 1982 through March 1987. The doubling time of the epidemic fell from about 6 months in 1982 to 15-16 months in 1986.

Asymmetric Social Interaction in Economics: Cigarette Smoking Among Young People in the United States, 1992-1999

We analyzed cigarette smoking among people aged 15 - 24 in approximately 90,000 households in the 1992 - 1999 U.S. Current Population Surveys. We modeled social influence as an informational externality, in which each young person's smoking informs her peers about its coolness.' The resulting family smoking game,' with each sibling's smoking endogenous, may have multiple equilibria. We found that the pro-smoking influence of a fellow smoker markedly exceeded the deterrent effect of a non-smoking peer. The phenomenon of asymmetric social influence has implications for financial markets, educational performance, criminal behavior, and other areas of inquiry where peer influence is important.

Heterogeneous Impact of the "Seguro Popular" Program on the Utilization of Obstetrical Services in Mexico, 2001-2006: A Multinomial Probit Model with a Discrete Endogenous Variable

Objective: We evaluated the impact of Seguro Popular (SP), a program introduced in 2001 in Mexico primarily to finance health care for the poor. We studied the effect of SP on pregnant women's access to obstetrical services. Data: We analyzed the cross-sectional 2006 National Health and Nutrition Survey (ENSANUT), focusing on the responses of 3,890 women who delivered babies during 2001-2006 and whose households lacked employer-based health care coverage. Methods: We formulated a multinomial probit model that distinguished between three mutually exclusive sites for delivering a baby: a health unit accredited by SP; a clinic run by the Department of Health (Secretaria de Salud, or SSA); and private obstetrical care. Our model accounted for the endogeneity of the household's binary decision to enroll in the SP program. Results: Women in households that participated in the SP program had a much stronger preference for having a baby in a SP-sponsored unit rather than paying out of pocket for a private delivery. At the same time, participation in SP was associated with a stronger preference for delivering in the private sector rather than at a state-run SSA clinic. On balance, the Seguro Popular program reduced pregnant women's attendance at an SSA clinic much more than it reduced the probability of delivering a baby in the private sector. The impacts of the SP program at the individual and population levels varied with the woman's education and health, as well as the assets and location (rural versus urban) of the household. Conclusions: The SP program had a robust, significantly positive impact on access to obstetrical services. Our finding that women enrolled in SP switched from non-SP state-run facilities, rather than from out-of-pocket private services, is important for public policy and requires further exploration.

Application of Computable General Equilibrium Model to Derive Impacts of Surface Water Reallocation Policy

Resource /Energy Economics and Policy,

Registration of N614, A3N615, N616, and N617 Shattercane Genetic Stocks with Cytoplasmic or Nuclear Male Sterility and Juicy or Dry Midribs

Four shattercane [Sorghum bicolor subsp. drummondii (Nees ex Steud.) de Wet ex Davidse] genetic stocks—N614 (Reg. No. GS-652, PI 665684), A3N615 (Reg. No. GS-651, PI 665683), N616 (Reg. No. GS-653, PI 665685), and N617 (Reg. No. GS-654, PI 665686)—with A3 cytoplasmic male sterility or the nuclear male sterility gene ms3 containing either juicy (dd) or dry (DD) culms were developed jointly by the USDA-ARS; the Iowa Agricultural and Home Economics Experiment Station, College of Agriculture and Life Sciences, Iowa State University; and the Agricultural Research Division, Institute of Agriculture and Natural Resources, University of Nebraska. The stocks were released in July 2011. The source material for these genetic stocks was isolated from an archetypical shattercane population found near Lincoln, NE. Release of these genetic stocks makes available shattercane lines with both A3 cytoplasmic male sterility, and ms3 genetic (nuclear) male sterility to facilitate crossing. These genetic stocks also contain juicy (dd) or dry (DD) culms, a visible genetic marker to facilitate screening progeny resulting from crosses. The genetic stocks have immediate application for basic research involving gene flow from cultivated sorghum [Sorghum bicolor (L.) Moench] to shattercane and on the fitness of offspring resulting from such crosses

Oscillatory Flows Induced by Microorganisms Swimming in Two-dimensions

We present the first time-resolved measurements of the oscillatory velocity field induced by swimming unicellular microorganisms. Confinement of the green alga C. reinhardtii in stabilized thin liquid films allows simultaneous tracking of cells and tracer particles. The measured velocity field reveals complex time-dependent flow structures, and scales inversely with distance. The instantaneous mechanical power generated by the cells is measured from the velocity fields and peaks at 15 fW. The dissipation per cycle is more than four times what steady swimming would require.Comment: 4 pages, 4 figure

Tobacco control campaign in Uruguay: Impact on smoking cessation during pregnancy and birth weight

We analyzed a nationwide registry of all pregnancies in Uruguay during 2007-2013 to assess the impact of three types of tobacco control policies: (1) provider-level interventions aimed at the treatment of nicotine dependence, (2) national-level increases in cigarette taxes, and (3) national-level non-price regulation of cigarette packaging and marketing. We estimated models of smoking cessation during pregnancy at the individual, provider and national levels. The rate of smoking cessation during pregnancy increased from 15.4% in 2007 to 42.7% in 2013. National-level non-price policies had the largest estimated impact on cessation. The price response of the tobacco industry attenuated the effects of tax increases. While provider-level interventions had a significant effect, they were adopted by relatively few health centers. Quitting during pregnancy increased birth weight by an estimated 188. g. Tobacco control measures had no effect on the birth weight of newborns of non-smoking women. Keywords: Economic evaluation; Cigarette taxes; Package warnings; Advertising bans; Tobacco contro