The Growing Importance of Cognitive Skills in Wage Determination

Using data from two longitudinal surveys of American high school seniors, we show that basic cognitive skills had a larger impact on wages for 24-year-old men and women in 1986 than in 1978. For women, the increase in the return to cognitive skills between 1978 and 1986 accounts for all of the increase in the wage premium associated with post-secondary education. We also show that high school seniors' mastery of basic cognitive skills had a much smaller impact on wages two years after graduation than on wages six years after graduation.

Equilibrium orbit analysis in a free-electron laser with a coaxial wiggler

An analysis of single-electron orbits in combined coaxial wiggler and axial guide magnetic fields is presented. Solutions of the equations of motion are developed in a form convenient for computing orbital velocity components and trajectories in the radially dependent wiggler. Simple analytical solutions are obtained in the radially-uniform-wiggler approximation and a formula for the derivative of the axial velocity $v_{\|}$ with respect to Lorentz factor $\gamma$ is derived. Results of numerical computations are presented and the characteristics of the equilibrium orbits are discussed. The third spatial harmonic of the coaxial wiggler field gives rise to group $III$ orbits which are characterized by a strong negative mass regime.Comment: 13 pages, 9 figures, to appear in phys. rev.

Indigenous knowledge and its implication for agricultural development and agricultural education: a case study of the Vedic tradition in Nepal

This dissertation is about the meaning and relevance, in today\u27s world, of indigenous knowledge, and particularly the traditional cosmologies and sacred beliefs that underly this knowledge. The case of Vedic knowledge in Nepal is studied to illustrate traditional agriculture within a cosmological framework and to provide an holistic, indigenous perspective on development with emphasis on sustainable, indigenous approaches to agriculture and related sectors in Nepal. Indigenous knowledge is defined from an indigenous perspective and an alternative, emic approach to understanding the role of indigenous knowledge in development and the synthesis of modern and indigenous knowledge systems is proposed. Implications are drawn for agricultural education philosophy in Nepal, and conclusions are reached and recommendations made for the global approach to indigenous knowledge in light of the indigenous perspective

Do Teacher Absences Impact Student Achievement? Longitudinal Evidence from One Urban School District

Rates of employee absences and the effects of absences on productivity are topics of conversation in many organizations in many countries. One reason is that high rates of employee absence may signal weak management and poor labor-management relations. A second reason is that reducing rates of employee absence may be an effective way to improve productivity. This paper reports the results of a study of employee absences in education, a large, labor-intensive industry. Policymakers' concern with teacher absence rests on three premises: (1) that a significant portion of teachers' absences is discretionary, (2) that teachers' absences have a nontrivial impact on productivity, and (3) that feasible policy changes could reduce rates of absence among teachers. This paper presents the results of an empirical investigation of the first two of these premises; it discusses the third premise. We employ a methodology that accounts for time-invariant differences among teachers in skill and motivation. We find large variation in adjusted teacher absence rates among schools. We estimate that each 10 days of teacher absences reduce students' mathematics achievement by 3.3 percent of a standard deviation.

Do the Cognitive Skills of School Dropouts Matter in the Labor Market?

Does the U.S. labor market reward cognitive skill differences among high school dropouts, the members of the labor force with the least educational attainments? This paper reports the results of an exploration of this question, using a new data set that provides information on the universe of dropouts who last attempted the GED exams in Florida and New York between 1984 and 1990. The design of the sample reduces variation in unmeasured variables such as motivation that are correlated with cognitive skills. We examine the labor market returns to basic cognitive skills as measured by GED test scores. We explore whether the returns differ by gender and race. The results indicate quite large earnings returns to cognitive skills for both male and female dropouts, and for white and non-white dropouts. The earnings payoff to skills increases with age.

Who Benefits from Obtaining a GED? Evidence from High School and Beyond

This paper examines the value of the GED credential and the conventional high school diploma in explaining the earnings of 27-year-old males in the early 1990s. The data base is the High School & Beyond sophomore cohort. We replicate the basic findings of prior studies that implicitly assume the labor market value of the GED credential does not depend on the skills with which dropouts left school. We show that these average effects mask a more complicated pattern. Obtaining a GED is associated with higher earnings at age 27 for those male dropouts who had very weak cognitive skills as tenth graders, but not for those who had stronger cognitive skills as tenth graders.

Expanding School Enrollment by Subsidizing Private Schools: Lessons from Bogotá

Many countries use tax revenues to subsidize private schools. Whether these policies meet social objectives depends, in part, on the relative quality of education provided by the two types of schools. We use data on elementary school students and their teachers in Bogotá, Colombia to examine difference in resource mixes and differences in the relative effectiveness of public and private schools. We find that, on average, the schools in the two sectors are equally effective. However, they produce education using very different resource combinations. Moreover, there are large differences in the effectiveness of schools in both sectors, especially in the private sector. The results of our analysis shed light on the quantity-quality tradeoff that governments in many developing countries face in deciding how to use scarce educational resources.

Experimental Demonstration of Fermi Surface Effects at Filling Factor 5/2

Using small wavelength surface acoustic waves (SAW) on ultra-high mobility heterostructures, Fermi surface properties are detected at 5/2 filling factor at temperatures higher than those at which the quantum Hall state forms. An enhanced conductivity is observed at 5/2 by employing sub 0.5 micron wavelength SAW, indicating a quasiparticle mean-free-path substantially smaller than that in the lowest Landau level. These findings are consistent with the presence of a filled Fermi sea of composite fermions, which may pair at lower temperatures to form the 5/2 ground state.Comment: 11 pages, 4 figure

Dietary flavonoid intake and weight maintenance: three prospective cohorts of 124,086 US men and women followed for up to 24 years

Objective: To examine whether dietary intake of specific flavonoid sub-classes is associated with weight change over time, including flavonols, flavones, flavanones, flavan-3-ols, anthocyanins, and flavonoid polymers. Design: Three prospective cohort studies. Setting: Health professionals in the United States. Participants: 124,086 men and women participating in the Health Professionals Follow-up Study (HPFS), Nurses’ Health Study (NHS), and Nurses’ Health Study II (NHS II). Main outcome measure: Self-reported change in weight over multiple 4-year time intervals between 1986 and 2011. Results: Increased consumption of most flavonoid sub-classes, including flavonols, flavan-3-ols, anthocyanins, and flavonoid polymers was inversely associated with weight change over 4-year time intervals, after adjustment for simultaneous changes in other lifestyle factors including other aspects of diet, smoking status, and physical activity. In the pooled results, the greatest magnitude of association was observed for anthocyanins (-0.22 lbs, 95% CI -0.30 to -0.15 lbs per additional SD/day, 10 mg), flavonoid polymers (-0.18 lbs, 95% CI -0.28 to -0.08 lbs per additional SD/day, 138 mg), and flavonols (-0.16 lbs, 95% CI -0.26 to -0.06 lbs per additional SD/day, 7 mg). After additional adjustment for fiber intake associations remained significant for anthocyanins, proanthocyanidins, and total flavonoid polymers but were attenuated and no longer statistically significant for other sub-classes. Conclusions: Higher intake of foods rich in flavonols, flavan-3-ols, anthocyanins, and flavonoid polymers, may contribute to weight maintenance in adulthood, and may help to refine dietary recommendations for the prevention of obesity and its potential sequelae

Stability and effective masses of composite-fermions in the first and second Landau Level

We propose a measure of the stability of composite fermions (CF's) at even-denominator Landau-level filling fractions. Assuming Landau-level mixing effects are not strong, we show that the CF liquid at $\nu=2+1/2$ in the $n=1$ Landau level cannot exist and relate this to the absence of a hierarchy of incompressible states for filling fractions $2+1/3 < \nu < 2+2/3$. We find that a polarized CF liquid should exist at $\nu=2+1/4$. We also show that, for CF states, the variation with system size of the ground state energy of interacting electrons follows that for non-interacting particles in zero magnetic field. We use this to estimate the CF effective masses.Comment: 9 pages, Revtex, PSIZ-TP-940