J. Enders,* T. Baumann, B. A. Brown, N. H. Frank, P. G. Hansen, P. R. Heckman, B. M. Sherrill, A. Stolz, M. Thoennessen, J. A. Tostevin, E. J. Tryggestad, S. Typel, and M. S. Wallace National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824, USA Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA Departme...

The main purpose of this paper is to investigate the identifiability of duration models with multiple spells. We prove that the results of Elbers and Ridder (1982) and Heckman and Singer (1984) can be generalized to multi–spell models with lagged duration dependence. We also prove that without lagged duration dependence, the identification result does not depend on moment conditions or tail con...

In this paper, we derive explicit product formulas and positive convolution structures for three continuous classes of Heckman-Opdam hypergeometric functions of type BC. For specific discrete series of multiplicities these hypergeometric functions occur as the spherical functions of non-compact Grassmann manifolds G/K over one of the (skew) fields F = R,C,H. We write the product formula of thes...

Two dimensional quantum Yang-Mills theory is reexamined using a non-abelian version of the Duistermaat-Heckman integration formula to carry out the functional integral. This makes it possible to explain properties of the theory that are inaccessible to standard methods and to obtain general expressions for intersection pairings on moduli spaces of flat connections on a two dimensional surface. ...

• We prove several best-possible lower bounds in terms of the order and the average degree for the independence number of graphs which are connected and/or satisfy some odd girth condition. Our main result is the extension of a lower bound for the independence number of triangle-free graphs of maximum degree at most 3 due to Heckman and Thomas [A New Proof of the Independence Ratio of Triangle-...

This paper is concerned with the problem of classifying tuples natural numbers a1,…,aK and b1,…,bL such that ratio factorials ∏i=1K(ain)!∕∏j=1L(bjn)! an integer for all n. A complete solution to this only known in case L−K=1, due work Bober building on observation Rodriguez Villegas, which relies Beukers–Heckman classification algebraic hypergeometric functions. We provide alternative proof res...

Kamenev and Mezard, and Yurkevich and Lerner, have recently shown how to reproduce the large-frequency asymptotics of the energy level correlations for disordered electron systems, by doing perturbation theory around the saddles of the compact nonlinear σ model derived from fermionic replicas. We present a critical review of their procedure and argue that its validity is limited to the perturba...

Materials and methods A Binary Probit model ws used to measure the participation in work force and a two-stage Heckman model to measure worked h and productivity. Each model is estimated separately for both gender individuals, with and without disease, according three distinct definitions for DM: Restrict, Broad and Comorbidities. To capture the counterfactual effect, the model was calculated f...

We are grateful to Ellen MacKenzie, Gregory Jurkovich, and Frederick Rivara for providing access to the NSCOT data and to Jin Wang for her assistance in data preparation and analysis. We also thank Jim Heckman and Philipp Eisenhauer for suggestions about computations. All errors are ours. Dr. Basu acknowledges financial support from National Cancer Institute research grants RC4 CA155809 (PI Bas...

This article examines the impact of sociodemographic factors on individual consumption of alcohol in the United States using the Heckman procedure and logit analysis. Factors considered are urbanization, race, ethnicity, region, weight, height, sex, food stamp participation, employment status, diet status, day of consumption, household size, age, and income, All the variables, with the exceptio...