Vertex-pursuit in random directed acyclic graphs

We examine a dynamic model for the disruption of information flow in hierarchical social networks by considering the vertex-pursuit game Seepage played in directed acyclic graphs (DAGs). In Seepage, agents attempt to block the movement of an intruder who moves downward from the source node to a sink. The minimum number of such agents required to block the intruder is called the green number. We propose a generalized stochastic model for DAGs with given expected total degree sequence. Seepage and the green number is analyzed in stochastic DAGs in both the cases of a regular and power law degree sequence. For each such sequence, we give asymptotic bounds (and in certain instances, precise values) for the green number

Optical modes in oxide-apertured micropillar cavities

We present a detailed experimental characterization of the spectral and spatial structure of the confined optical modes for oxide-apertured micropillar cavities, showing good-quality Hermite-Gaussian profiles, easily mode-matched to external fields. We further derive a relation between the frequency splitting of the transverse modes and the expected Purcell factor. Finally, we describe a technique to retrieve the profile of the confining refractive index distribution from the spatial profiles of the modes.Comment: 4 pages, 3 figure

The Cop Number of the One-Cop-Moves Game on Planar Graphs

Cops and robbers is a vertex-pursuit game played on graphs. In the classical cops-and-robbers game, a set of cops and a robber occupy the vertices of the graph and move alternately along the graph's edges with perfect information about each other's positions. If a cop eventually occupies the same vertex as the robber, then the cops win; the robber wins if she can indefinitely evade capture. Aigner and Frommer established that in every connected planar graph, three cops are sufficient to capture a single robber. In this paper, we consider a recently studied variant of the cops-and-robbers game, alternately called the one-active-cop game, one-cop-moves game or the lazy-cops-and-robbers game, where at most one cop can move during any round. We show that Aigner and Frommer's result does not generalise to this game variant by constructing a connected planar graph on which a robber can indefinitely evade three cops in the one-cop-moves game. This answers a question recently raised by Sullivan, Townsend and Werzanski.Comment: 32 page

Avaliação de genótipos de soja. I. Ensaios preliminares de primeiro e de segundo anos.

bitstream/item/133642/1/ID10244-1992-1993sojaresultados-p35-42.pdfTrabalho apresentado na XXI Reunião de Pesquisa de Soja da Região Sul, Santa Rosa, 1993

Melhoramento de soja. II. Avaliação de progenies e formação de novas linhagens.

bitstream/item/133636/1/ID10355-1992-1993sojaresultados-p29-32.pdfTrabalho apresentado na XXI Reunião de Pesquisa de Soja da Região Sul, Santa Rosa, 1993

Melhoramento de soja. I. Hibridações, populações segrantes e seleção de plantas.

bitstream/item/133637/1/ID10354-1992-1993sojaresultados-p23-28.pdfTrabalho apresentado na XXI Reunião de Pesquisa de Soja da Região Sul, Santa Rosa, 1993

Avaliação de genótipos de soja. III. Ensaios finais.

bitstream/item/133640/1/ID10246-1992-1993sojaresultados-p49-54.pdfTrabalho apresentado na XXI Reunião de Pesquisa de Soja da Região Sul, Santa Rosa, 1993