Periodic orbit effects on conductance peak heights in a chaotic quantum dot

We study the effects of short-time classical dynamics on the distribution of Coulomb blockade peak heights in a chaotic quantum dot. The location of one or both leads relative to the short unstable orbits, as well as relative to the symmetry lines, can have large effects on the moments and on the head and tail of the conductance distribution. We study these effects analytically as a function of the stability exponent of the orbits involved, and also numerically using the stadium billiard as a model. The predicted behavior is robust, depending only on the short-time behavior of the many-body quantum system, and consequently insensitive to moderate-sized perturbations.Comment: 14 pages, including 6 figure

Thrips on fabaceous plants and weeds in an ecotone in northeastern Brazil

ABSTRACT: Thrips (Thysanoptera) on 33 species of Fabaceae (ornamental and forage) and some weed species were surveyed in areas of caatinga-cerrado ecotone in northeastern Brazil. Twenty species of thrips were identified, all of which are associated for the first time with the plants sampled in this study, totaling 26 new host associations, based on collections of immatures. Five species are probably new to science, illustrating the diversity of thrips in the region. A few thrips species that also occur as pests in other regions of Brazil are discussed. Our data extend the distribution area of thrips species and provide basic information on their associated plants

A simple proof of a primal affine scaling method

In this paper, we present a simpler proof of the result of Tsuchiya and Muramatsu on the convergence of the primal affine scaling method. We show that the primal sequence generated by the method converges to the interior of the optimum face and the dual sequence to the analytic center of the optimal dual face, when the step size implemented in the procedure is bounded by 2/3. We also prove the optimality of the limit of the primal sequence for a slightly larger step size of 2 q /(3 q −1), where q is the number of zero variables in the limit. We show this by proving the dual feasibility of a cluster point of the dual sequence.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44263/1/10479_2005_Article_BF02206821.pd