College drinking is a problem with severe academic, health, and safety consequences. The underlying social processes that lead to increased drinking activity are not well understood. Social Norms Theory is an approach to analysis and intervention based on the notion that students' misperceptions about the drinking culture on campus lead to increases in alcohol use. In this paper we develop an agent-based simulation model, implemented in MATLAB, to examine college drinking. Students' drinking behaviors are governed by their identity (and how others perceive it) as well as peer influences, as they interact in small groups over the course of a drinking event. Our simulation results provide some insight into the potential effectiveness of interventions such as social norms marketing campaigns.

Background: The application of social norms theory in the study of college drinking centers on the ideas that incorrect perceptions of drinking norms encourage problematic drinking behavior and that correcting misperceptions can mitigate problems. The design and execution of social norms interventions can be improved with a deeper understanding of causal mechanisms connecting misperception to drinking behavior.Methods: We develop an agent-based computational simulation that uses identity control theory and peer influence (PI) to model interactions that affect drinking. Using data from the College Alcohol Survey and Social Norms Marketing Research Project, we inform model parameters for agent drinking identities and perceptions. We simulate social norms campaigns that reach progressively larger fractions of the student population, and we consider the strength of the campaign in terms of changing student perception and resulting behavior.Results: We observe a general reduction in heavy episodic drinking (HED) as students are affected by the intervention. As campaigns reached larger fractions of students, the reduction rate diminishes, in some cases actually making a slight reverse. The way in which students "take the message to heart" can have a significant impact as well: The psychological factors involved in identity control and PI have both positive and negative effects on HED rates. With whom agents associate at drinking events also impacts drinking behavior and intervention effectiveness.Conclusions: Simulations suggest that reducing misperception can reduce HED. When agents adhere strongly to identity verification and when misperceptions affect identity appraisals, social norms campaigns can bring about large reductions. PI, self-monitoring, and socializing with like-drinking peers appear to moderate the effect.

The present paper presents a preliminary approach to the modeling of dynamic properties of the spatial assortment of alcohol outlets using agent-based techniques. Individual drinkers and business establishments are the core agent types. Drinkers assort themselves by frequenting establishments due to spatial and social (niche) motivations. We examine a number of questions concerning the feedback relationships between establishments targeting a particular niche clientele and the individuals seeking more desirable places to obtain alcohol.

We present triple differential cross-sections for the electron impact ionization of hydrogen and helium in energy sharing coplanar constant circle minus(12) = 180 degrees and coplanar energy sharing perpendicular plane geometries at impact energies of a few eV's above ionization threshold. We investigate the role of incident channel effects in determining the shape of the cross-section. We present cross-sections in the same geometries for the isoelectronic sequence of hydrogenic and helium-like ions with nuclear charges up to Z = 10.

We present a new variational approach for calculating (e,2e) and (γ,2e)processes. We consider the general theory for the electron-impact ionization of atomic hydrogen and we deduce a formula for the scattering amplitude in terms of a surface integral over a five-dimensional hypersurface. We consider configuration space to be divided into three regions separated by five-dimensional hypersurfaces. We calculate the R-matrix on the surface of the innermost hypersurface using a variationally determined two-electron R-operator, a linear operator that relates function values to normal derivatives on the innermost bounding hypersurface inside which the function satisfies the Schrödinger equation. We then use the Light Walker propagation technique, modified by the symmetry condition at rs=rf, to propagate our variationally determined R-matrix through a large volume until we reach the boundary of our second hypersurface. We calculate the S-matrix on this hypersurface and use it to remove the incoming flux and deduce the outgoing wave which is matched to one that has been brought in from some asymptotically large distance. It is shown that it is possible to reduce the five-dimensional integral over the hypersurface to a single numerical integration, times a finite sum over angular terms, thus facilitating the evaluation of the scattering amplitude. The method we propose is computationally efficient. Results will be presented for a number of simple test cases.

We investigate and compare two asymptotic wave functions for atomic double ionization in the region where the distance between the escaping electrons is small when compared to the distance from the nucleus. The first of the forms was derived by Alt and Mukhamedzhanov and solves the three body Schrodinger equation to an order of 1/r2. The second wave function was derived by Engelns, Klar and Malcherek for use in all asymptotic regimes. These forms will be compared numerically and analytically.