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.

Knowledge Reuse for Customization: Metamodels in an Open Design Community for 3d Printing

Theories of knowledge reuse posit two distinct processes: reuse for replication and reuse for innovation. We identify another distinct process, reuse for customization. Reuse for customization is a process in which designers manipulate the parameters of metamodels to produce models that fulfill their personal needs. We test hypotheses about reuse for customization in Thingiverse, a community of designers that shares files for three-dimensional printing. 3D metamodels are reused more often than the 3D models they generate. The reuse of metamodels is amplified when the metamodels are created by designers with greater community experience. Metamodels make the community's design knowledge available for reuse for customization-or further extension of the metamodels, a kind of reuse for innovation

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.

The Fight Against Colorism in the Black Community

Since centuries ago African Americans have experienced discrimination more times than any other minority group. In 1983, Alice Walker introduced the term colorism which is, prejudice or discrimination against individuals with a dark skin tone, typically among people of the same ethnic or racial group. Literature suggest this stems back to slavery when slave masters awarded special privileges to African Americans of a lighter skin tone. This study examines the relationship between skin tones and the effects it has on the African American Culture