Northampton Community College

About: Northampton Community College is a education organization based out in Bethlehem, Pennsylvania, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 3410 authors who have published 4582 publications receiving 130398 citations. The organization is also known as: Northampton County Area Community College.

Fifteen years of problem gambling prevalence research: What do we know? Where do we go?

Abstract: This paper charts the rapid growth of problem gambling prevalence research in North America and internationally. Looking beyond the overall prevalence of problem gambling in the general population, the results of these studies support the notion of a link between the expansion of legal gambling opportunities and the prevalence of problem gambling as well as the notion that the characteristics of problem gamblers change in response to changes in the availability of specific types of gambling. The results of these studies also challenge existing concepts and definitions of problem gambling. In the future, it will be important to improve how problem gambling prevalence research is done. Such work is likely to include changes in how we measure gambling problems as well as requiring us to take steps to overcome obstacles in achieving representative samples of the population and obtaining valid and accurate information.

Parametrically excited surface waves: two-frequency forcing, normal form symmetries, and pattern selection.

Abstract: Motivated by experimental observations of exotic standing wave patterns in the two-frequency Faraday experiment, we investigate the role of normal form symmetries in the pattern selection problem. With forcing frequency components in ratio m/n, where m and n are co-prime integers, there is the possibility that both harmonic and subharmonic waves may lose stability simultaneously, each with a different wavenumber. We focus on this situation and compare the case where the harmonic waves have a longer wavelength than the subharmonic waves with the case where the harmonic waves have a shorter wavelength. We show that in the former case a normal form transformation can be used to remove all quadratic terms from the amplitude equations governing the relevant resonant triad interactions. Thus the role of resonant triads in the pattern selection problem is greatly diminished in this situation. We verify our general results within the example of one-dimensional surface wave solutions of the Zhang-Vinals model of the two-frequency Faraday problem. In one-dimension, a 1:2 spatial resonance takes the place of a resonant triad in our investigation. We find that when the bifurcating modes are in this spatial resonance, it dramatically effects the bifurcation to subharmonic waves in the case of forcing frequencies are in ratio 1/2; this is consistent with the results of Zhang and Vinals. In sharp contrast, we find that when the forcing frequencies are in ratio 2/3, the bifurcation to (sub)harmonic waves is insensitive to the presence of another spatially-resonant bifurcating mode.