k-Nearest neighbor models for microarray gene expression analysis and clinical outcome prediction.

In the clinical application of genomic data analysis and modeling, a number of factors contribute to the performance of disease classification and clinical outcome prediction. This study focuses on the k-nearest neighbor (KNN) modeling strategy and its clinical use. Although KNN is simple and clinically appealing, large performance variations were found among experienced data analysis teams in the MicroArray Quality Control Phase II (MAQC-II) project. For clinical end points and controls from breast cancer, neuroblastoma and multiple myeloma, we systematically generated 463,320 KNN models by varying feature ranking method, number of features, distance metric, number of neighbors, vote weighting and decision threshold. We identified factors that contribute to the MAQC-II project performance variation, and validated a KNN data analysis protocol using a newly generated clinical data set with 478 neuroblastoma patients. We interpreted the biological and practical significance of the derived KNN models, and compared their performance with existing clinical factors.

Beyond single mothers: cohabitation and marriage in the AFDC program.

We investigate the extent and implications of cohabitation and marriage among U.S. welfare recipients. An analysis of four data sets (the Current Population Survey, the National Survey of Families and Households, the Panel Study of Income Dynamics, and the National Longitudinal Survey of Youth) shows significant numbers of cohabitors among recipients of AFDC. An even more surprising finding is the large number of married women on welfare. We also report the results of a telephone survey of state AFDC agencies conducted to determine state rules governing cohabitation and marriage. The survey results indicate that, in a number of respects, AFDC rules encourage cohabitation. Finally, we conduct an analysis of the impact of AFDC rules on cohabitation, marriage, and single motherhood and find weak evidence in support of incentives to cohabit.

Health care coverage for children who are on and off welfare.

Access to adequate health insurance is a key concern of families with children at all income levels. Since 1965, mothers and children on welfare have had health care coverage through the Medicaid program, which has provided a health care safety net for welfare recipients. Although most Americans are insured through their employers, families who leave welfare for employment often find themselves in jobs that do not offer health care coverage, adding to the ranks of the uninsured. This article examines the extent to which poor children and their mothers have private insurance, Medicaid, or no health insurance at all. It documents how recent expansions of Medicaid eligibility to low-income children who do not receive welfare have improved the insurance status of children, though these changes have not helped the mothers who leave welfare for work. Citing evidence that health insurance options influence the welfare and employment decisions of women whose families face health problems, the article suggests that implementing welfare reform at a time when rates of private insurance coverage are declining will be challenging and may expose some families to health risks.

Elevated endothelin-1 levels and persistent stage IV hypertension in a nonvolume overloaded anephric patient.

Persistent hypertension after nephrectomy is in most cases due to increased fluid volume. Endothelin-1 is a potent endogenous vasoconstrictor peptide. Its role in the development and maintenance of hypertension is not completely understood, but it might be significant in some cases. We report a case of stage IV hypertension after nephrectomy with elevated endothelin-1 levels and no volume overload.

Cohort trends in the lifetime distribution of female family headship in the United States, 1968-1985.

We use the PSID Relationship File to estimate cohort trends in the lifetime incidence and duration of female family headship. Hazard (event-history) techniques are used to estimate movements into and out of headship, accounting for duration dependence and left-censored spells. The mean number of years spent in headship between ages 14 and 59 rose dramatically over the period. The increase arose from an increased number of headship spells, including an increase in the number of women ever experiencing headship, but not all from an increase in durations of headship spells; those decreased slightly.

State AFDC rules regarding the treatment of cohabitors: 1993.

This article reports the results of a survey of State Aid to Families with Dependent Children (AFDC) rules regarding the treatment of unrelated cohabitors in households containing AFDC units. We examine State treatment of cash and in-kind contributions by cohabitors and find that the AFDC grant is usually not affected in the cohabitor makes in-kind contributions toward food and shelter expenses of the household. However, the grant generally is reduced if the cohabitor contributes cash to the AFDC unit unless the cash is for shared household expenses. In addition, a few States have specific policies toward cohabitors that are not based on initial evidence of cohabitor contributions.

Rapid direct determination of lead in evaporated milk by anodic stripping voltammetry without sample pretreatment.

The method presented describes the direct determination of lead in evaporated milk in which the milk ashing step prior to analysis is eliminated. Digital instrument readout units are microgram Pb/mL milk. Total analysis time after instrument calibration is less than 3 min per sample. Range of the method is 0.05-1.0 ppm lead in milk, and precision of the method expressed by relative standard deviation of duplicate pairs ranged from 30% at 0.1 micrograms/mL to 3% at 1.0 micrograms/mL of lead in milk. The method compares favorably with the AOAC official first action anodic stripping voltammetric method (25.074). In addition, the method appears to work equally well for skim evaporated milk, sweetened condensed milk, and nonfat powdered dry milk when the latter two are reconstituted with water according to product label instructions. Recovery and interference studies are presented.

Direct determination of lead in evaporated milk and apple juice by anodic stripping voltammetry: collaborative study.

A method for the direct determination of lead in evaporated milk and in fruit juice with no prior sample digestion was successfully collaborated by 13 laboratories. The anodic stripping voltammetric (ASV) method studied consisted of adding 0.2 mL aliquots of evaporated milk or 0.3 mL aliquots of fruit juice to 2.9 mL of a dechelating reagent, Metexchange. The reagent-sample mixture is then analyzed for lead by ASV with no further sample preparation. Each collaborator received 24 samples, 2 each at 5 different levels (0.07-0.70 ppm for spiked evaporated milk and 0.09-0.87 ppm for spiked apple juice) along with duplicate practice samples of labeled lead content at each of 2 levels for each sample type. All unknowns were coded with random numbers. Approximately 69% of the reporting laboratories had never analyzed either evaporated milk or fruit juice for lead. Average time between receipt of samples and reporting of results was 1.6 days for all laboratories. The pooled variations between duplicate determinations for apple juice and evaporated milk were 0.00059 and 0.00043, respectively. The method was adopted official first action for both fruit juice and evaporated milk.

Postwar fertility cycles and the Easterlin hypothesis: a life-cycle approach.

PIP: The Easterlin hypothesis is discussed in the context of the life-cycle model. Fertility rates rose by 15% after World War II, and have fallen steadily since. The Easterlin hypothesis states that such a pattern could be generated if each generation makes its fertility decisions based on its own income relative to the income of its parental generation. The income of one generation determines the level of material well-being to which its children become accustomed; when the children grow up they will desire material goods rather than children in order to retain the lifestyle they are accustomed to. In the traditional statement of the hypothesis, relative income is defined as some ratio of the current incomes of 2 generations at particular points in time; from the viewpoint of the life-cycle theory, the concept of the income of a cohort is replaced by the concept of lifetime wealth, the value of the income received over the entire life cycle. In this article, a value of lifetime wealth is constructed for each of the cohorts of childbearing age in the postwar period and for each of their parental cohorts. Regression analysis is employed to determine whether the lifetime wealth of a cohorts' parents significantly affects its fertility. Parental wealth has a strong negative effect on a cohort's age-specific fertility rate and own-cohort wealth is found to have a positive effect on fertility rates. This article contains a discussion of the life-cycle model, explains the regression equation, presents the method used to estimate lifetime wealth and fertility regressions, and provides an examination of the effect of own and parental wealth on a cohort's pattern of female labor force participation. There appear to be underlying trends in fertility rates that are independent of relative wealth, but this article demonstrates that the Easterlin hypothesis provides at least a strong partial explanation for postwar fertility cycles.^ieng

Electrolytic determination of surface lead in empty metal containers.

The lead content of an empty metal container (tin can) can be determined by an electrolytic process using a constant voltage power supply and dilute acid electrolyte. The ionic lead in the solution after electrolysis is determined by anodic stripping voltammetry.