Teen Drinking and Education Attainment: Evidence From Two-Sample Instrumental Variables (TSIV) Estimates

Recent research has suggested that one of the important consequences of teen drinking is reduced scholastic achievement and that state excise taxes on beer and minimum legal drinking ages (MLDA) as policy instruments can have a positive impact on educational attainment. But there is reason to ask whether the results are empirically sound. Prior research as assumed the decision to drink is made independently of schooling decisions and estimations that have recognized potential simultaneity in these decisions may be poorly identified since they rely only on the cross-state variation in beer taxes and MLDA as exogenous determinants of teen drinking. A more convincing strategy would rely on the within-state variation in alcohol availability over time. We use the increases in the state MLDA during the late 70's and 80's as an exogenous source of variation in teen drinking. Using data from the 1977-92 Monitoring the Future (MTF) surveys, we show that teens with an MLDA of 18 were more likely to drink than teens with a higher drinking age. If teen drinking did reduce educational attainment then it should have risen within a state after the MLDA was increased. Using data from over 1.3 million respondents from the 1960-1969 birth cohorts in the 1990 Public-Use Microdata Sample (PUMS) we find that changes in the MLDA had small effects on educational attainment measured by high school completion, college entrance and completion. A new method developed by Angrist and Krueger (1992, 1995) lets us tie these results together. Using matched cohorts from the MTF and PUMS data sets, we report two-sample instrumental variables (TSIV) estimates of the effect of teen drinking on educational attainment. These estimates are smaller than corresponding single-equation probit estimates, indicating that teen drinking does not have an independent effect on educational attainment.

Structural Stability and Renormalization Group for Propagating Fronts

A solution to a given equation is structurally stable if it suffers only an infinitesimal change when the equation (not the solution) is perturbed infinitesimally. We have found that structural stability can be used as a velocity selection principle for propagating fronts. We give examples, using numerical and renormalization group methods.Comment: 14 pages, uiucmac.tex, no figure

A simple nutrition screening tool for hemodialysis nurses

Objective : To assess the reliability of a nurse-performed nutrition screening tool (NST) for hemodialysis (HD) patients to identify nutritionally at-risk patients.Design : Tool reliability assessment.Setting and Participants : The setting was nine non-hospital private (n = 3) and public (n = 6) HD units in Australia (two rural and seven metropolitan). Participants were 112 HD patients.Results : A total of 112 HD patients (male = 65, female = 47) from 9 non-hospital HD units in Australia (seven metropolitan and two rural) were screened with the NST and the outcome of dietitian referral compared with Standard Dietitians Assessment. The mean age of patients was 57.6 years. Overall, the NST showed a sensitivity of 0.84 (range, 0.71 to 0.94; P &lt; .05) and a specificity of 0.9 (range, 0.82 to 0.98; P &lt; .05). The NST was more sensitive (sensitivity, 0.93 [range, 0.87 to 0.99; P &lt; .05]) and was more specific for men (specificity, 0.92 [range, 0.85 to 0.99; P &lt; .05]). Specificity was very strong in metropolitan patients (specificity, 0.94 [range, 0.87 to 1.01; P &lt; .05]).Conclusions : The tool was more sensitive and specific than the NST previously reported by the same investigators. The tool is particularly specific in that it screens those patients not requiring dietitian intervention. The use of this tool may benefit HD units that do not have on-site or regular dietetic support to prioritize patients needing dietitian intervention.<br /

Multiple Front Propagation Into Unstable States

The dynamics of transient patterns formed by front propagation in extended nonequilibrium systems is considered. Under certain circumstances, the state left behind a front propagating into an unstable homogeneous state can be an unstable periodic pattern. It is found by a numerical solution of a model of the Fr\'eedericksz transition in nematic liquid crystals that the mechanism of decay of such periodic unstable states is the propagation of a second front which replaces the unstable pattern by a another unstable periodic state with larger wavelength. The speed of this second front and the periodicity of the new state are analytically calculated with a generalization of the marginal stability formalism suited to the study of front propagation into periodic unstable states. PACS: 47.20.Ky, 03.40.Kf, 47.54.+rComment: 12 page

Renormalization Group Theory And Variational Calculations For Propagating Fronts

We study the propagation of uniformly translating fronts into a linearly unstable state, both analytically and numerically. We introduce a perturbative renormalization group (RG) approach to compute the change in the propagation speed when the fronts are perturbed by structural modification of their governing equations. This approach is successful when the fronts are structurally stable, and allows us to select uniquely the (numerical) experimentally observable propagation speed. For convenience and completeness, the structural stability argument is also briefly described. We point out that the solvability condition widely used in studying dynamics of nonequilibrium systems is equivalent to the assumption of physical renormalizability. We also implement a variational principle, due to Hadeler and Rothe, which provides a very good upper bound and, in some cases, even exact results on the propagation speeds, and which identifies the transition from ` linear'- to ` nonlinear-marginal-stability' as parameters in the governing equation are varied.Comment: 34 pages, plain tex with uiucmac.tex. Also available by anonymous ftp to gijoe.mrl.uiuc.edu (128.174.119.153), file /pub/front_RG.tex (or .ps.Z

Liesegang patterns: Effect of dissociation of the invading electrolyte

The effect of dissociation of the invading electrolyte on the formation of Liesegang bands is investigated. We find, using organic compounds with known dissociation constants, that the spacing coefficient, 1+p, that characterizes the position of the n-th band as x_n ~ (1+p)^n, decreases with increasing dissociation constant, K_d. Theoretical arguments are developed to explain these experimental findings and to calculate explicitly the K_d dependence of 1+p.Comment: RevTex, 8 pages, 3 eps figure

Perturbative Linearization of Reaction-Diffusion Equations

We develop perturbative expansions to obtain solutions for the initial-value problems of two important reaction-diffusion systems, viz., the Fisher equation and the time-dependent Ginzburg-Landau (TDGL) equation. The starting point of our expansion is the corresponding singular-perturbation solution. This approach transforms the solution of nonlinear reaction-diffusion equations into the solution of a hierarchy of linear equations. Our numerical results demonstrate that this hierarchy rapidly converges to the exact solution.Comment: 13 pages, 4 figures, latex2