Directing store flyers to the appropriate audience

Grocery shoppers were questioned about the frequency of purchasing items that were featured in the store's flyers. This measure was used as the dependent variable in a multinomial logit model with the independent variables being various aspects of shopping behaviour, usage of store flyers, age and employment status. Since only one threshold parameter was significant, the four-level dependent variable was then collapsed and a binary model was estimated. This study evidenced that less than half of the respondents looked forward to receiving unsolicited flyers. Most shoppers read the flyers only to be informed of price specials that the store has to offer. The odds ratio of responding to store flyer deals among those who look forward to sales flyers is more than double the odds ratio of those who do not await the flyers, across every category of shopping frequency. Retailers could employ direct marketing to target specific audiences who look forward to receiving store flyers.\u

Phase diagrams and universality classes of random antiferromagnetic spin ladders

The random antiferromagnetic two-leg and zigzag spin-1/2 ladders are investigated using the real space renormalization group scheme and their complete phase diagrams are determined. We demonstrate that the first system belongs to the same universality class of the dimerized random spin-1/2 chain. The zigzag ladder, on the other hand, is in a random singlet phase at weak frustration and disorder. Otherwise, we give additional evidence that it belongs to the universality class of the random antiferromagnetic and ferromagnetic quantum spin chains, although the universal fixed point found in the latter system is never realized. We find, however, a new universal fixed point at intermediate disorder.Comment: 10 pages, 10 figure

Non-stochastic behavior of atomic surface diffusion on Cu(111) at all temperatures

Atomic diffusion is usually understood as a succession of random, independent displacements of an adatom over the surface's potential energy landscape. Nevertheless, an analysis of Molecular Dynamics simulations of self-diffusion on Cu(111) demonstrates the existence of different types of correlations in the atomic jumps at all temperatures. Thus, the atomic displacements cannot be correctly described in terms of a random walk model. This fact has a profound impact on the determination and interpretation of diffusion coefficients.Comment: 5 figure