This Monograph reports results from a study of the effects of supplementary feeding of newborn to 7-year-old children on their subsequent performance as adolescents and young adults (11-24 years) on a battery of psychoeducational and information-processing tests. The study, which began in 1969, was conducted in a nutritionally at-risk population in the Department of El Progreso, Eastern Guatemala. The intent was to test the hypothesis that protein deficiency in infants and children delays mental development.We report the effects of the nutritional intervention on cognition during infancy, the preschool period, and, more extensively, adolescence and early adulthood. Issues of differential effects from pre-versus postnatal supplement are excluded; similarly, the current analyses do not attend to the possible differential effect of specific nutrients. BACKGROUNDThis section describes the key theoretical and research issues in international nutrition and in developmental biology and psychology that were dominant at the time the study was launched (1969). The discussion aims to justify the study design that was chosen and the research questions of concern here. International Nutrition and the Protein GapCicely Williams's (1933) description of kwashiorkor and her suggestion that its etiology could be found in a deficiency of "amino acids or protein" became a landmark; thereafter, protein deficiency became the object of I. INTRODUCTIONThis Monograph reports results from a study of the effects of supplementary feeding of newborn to 7-year-old children on their subsequent performance as adolescents and young adults (11-24 years) on a battery of psychoeducational and information-processing tests. The study, which began in 1969, was conducted in a nutritionally at-risk population in the Department of El Progreso, Eastern Guatemala. The intent was to test the hypothesis that protein deficiency in infants and children delays mental development.We report the effects of the nutritional intervention on cognition during infancy, the preschool period, and, more extensively, adolescence and early adulthood. Issues of differential effects from pre-versus postnatal supplement are excluded; similarly, the current analyses do not attend to the possible differential effect of specific nutrients. BACKGROUNDThis section describes the key theoretical and research issues in international nutrition and in developmental biology and psychology that were dominant at the time the study was launched (1969). The discussion aims to justify the study design that was chosen and the research questions of concern here. International Nutrition and the Protein GapCicely Williams's (1933) description of kwashiorkor and her suggestion that its etiology could be found in a deficiency of "amino acids or protein" became a landmark; thereafter, protein deficiency became the object of intensive study and international concern.1 For at least the following four decades, protein was considered to be the major limiting factor in the diets of most undernourished ch...

Computer simulations of double-walled carbon nanotubes show that if the inner nanotube is pulled out part of the way and then released, then the inner tube exhibits damped oscillatory behavior at gigahertz frequencies. A simple mathematical model, formulated in terms of macroscopic ideas of friction, is shown to predict the observed behavior to a high degree of accuracy.