The experience of Catholic gay and lesbian Catholic secondary school teachers within Northern California : a participatory action research study

N

Remote Sensing of Giant Reed with QuickBird Satellite Imagery

QuickBird high resolution (2.8 m) satellite imagery was evaluated for distinguishing giant reed ( Arundo donax L.) infestations along the Rio Grande in southwest Texas. (PDF has 5 pages.

Distribution in homology classes and discrete fractal dimension

In this note we examine the proportion of periodic orbits of Anosov flows that lie in an infinite zero density subset of the first homology group. We show that on a logarithmic scale we get convergence to a discrete fractal dimension.Comment: 8 page

Fuchsian groups, coverings of Riemann surfaces, subgroup growth, random quotients and random walks

AbstractFuchsian groups (acting as isometries of the hyperbolic plane) occur naturally in geometry, combinatorial group theory, and other contexts. We use character-theoretic and probabilistic methods to study the spaces of homomorphisms from Fuchsian groups to symmetric groups. We obtain a wide variety of applications, ranging from counting branched coverings of Riemann surfaces, to subgroup growth and random finite quotients of Fuchsian groups, as well as random walks on symmetric groups. In particular, we show that, in some sense, almost all homomorphisms from a Fuchsian group to alternating groups An are surjective, and this implies Higman's conjecture that every Fuchsian group surjects onto all large enough alternating groups. As a very special case, we obtain a random Hurwitz generation of An, namely random generation by two elements of orders 2 and 3 whose product has order 7. We also establish the analogue of Higman's conjecture for symmetric groups. We apply these results to branched coverings of Riemann surfaces, showing that under some assumptions on the ramification types, their monodromy group is almost always Sn or An. Another application concerns subgroup growth. We show that a Fuchsian group Γ has (n!)μ+o(1) index n subgroups, where μ is the measure of Γ, and derive similar estimates for so-called Eisenstein numbers of coverings of Riemann surfaces. A final application concerns random walks on alternating and symmetric groups. We give necessary and sufficient conditions for a collection of ‘almost homogeneous’ conjugacy classes in An to have product equal to An almost uniformly pointwise. Our methods involve some new asymptotic results for degrees and values of irreducible characters of symmetric groups

Spectral Reflectance and Digital Image Relations Among Five Aquatic Weeds

This study reports on the use of an artificial quartz halogen lighting source to facilitate the acquisition of spectral light reflectance measurements and digital imaging of invasive aquatic weeds. Spectral leaf or leaf/stem reflectance measurements were made on five aquatic weeds: Eurasian watermilfoil (Myriophyllum spicatum L.), hydrilla [Hydrilla verticillata (L. F.) Royle], parrotfeather [Myriophyllum aquaticum (Vall.), waterhyacinth [Eichhornia crassipes (Mart.) Solms], and waterlettuce (Pistia stratiotes L.). Reflectance measurements were studied at five wavelengths of the electromagnetic spectrum: 450 nm (visible blue), 550 nm (visible green), 650 nm (visible red), 680 nm (visible red edge), and 850 nm (near-infrared). Reflectance values differed significantly (P= 0.05) among the species at all five wavelengths. However, more distinct separations among species occurred at the 550 nm, 650 nm, 680 nm, and 850 nm wavelengths. Reflectance differences among species were attributed to variable foliage coloration and vegetative density. Close range conventional color and color-infrared digital images of leaves or leaves/stems of the five species showed they differed in image tonal response. Reflectance measurements were related to the image tonal response of the plant species on both types of imagery. Supervised image classifications performed on both conventional color and color-infrared images showed the computer generally did an adequate job in identifying the image tonal responses of the weed species

Cissus sicyoides C. Linnaeus (Vitaceae), a Potential Exotic Pest in the Lower Rio Grande Valley, Texas

English:Cissus sicyoides C. Linnaeus, a perennial vine native to tropical Mexico, Central America, and the Caribbean, has recently been rediscovered in the Lower Rio Grande Valley,Texas. A dense population of this exotic species has been located in a brushy area along a canal network and in two adjacent citrus groves near Weslaco. This species produces a dense mantle that covers other vegetation, appears to be invasive, and may pose a potential weed problem in citrus in the Lower Rio Grande Valley. Spanish: Cissus sicyoides C. Linnaeus, una enredadera perene nativa de los trópicos de México, América Central y el Caribe, se ha redescubierto recientemente en el Bajo Valle del Río Grande,Texas. Una población densa de esta especie exótica ha sido localizada en una área de matorral a lo largo de una red de canales y en dos huertas adyacentes de cítricos cercanas a Weslaco. Esta especie produce un manto denso que cubre otra vegetación, es invasiva y puede tener el potencial de convertirse en una maleza problemática para el cultivo de cítricos en el Bajo Valle del Río Grande en Texas