Sewanee: The University of the South

About: Sewanee: The University of the South is a education organization based out in Sewanee, Tennessee, United States. It is known for research contribution in the topics: Population & Species richness. The organization has 8995 authors who have published 14790 publications receiving 320138 citations. The organization is also known as: Sewanee & The University of the South.

Trypanosoma avium of raptors (Falconiformes): phylogeny and identification of vectors

Abstract: Avian trypanosomes are widespread parasites of birds, the transmission of which remains mostly unclear, with various blood-sucking insects mentioned as possible vectors. A search for vectors of trypanosomes of sparrowhawk (Accipiter nisus), buzzard (Buteo buteo), lesser-spotted eagle (Aquila pomarina) and kestrel (Falco tinnunculus) was performed in Czech and Slovak Republics. Black flies (Eusimulium spp.), hippoboscid flies (Ornithomyia avicularia), mosquitoes (Culex pipiens pipiens) and biting midges (Culicoides spp.), trapped while attempting to feed on raptor nestlings, were found to contain trypanosomatids in their intestine. Trypanosomes from the raptors and blood-sucking insects were isolated, and their 18S rRNA sequences were used for species identification and for the inference of intra- and interspecific relationships. Together with the trypanosome isolated from a black fly, the bird trypanosomes formed a well-supported Trypanosoma avium clade. The isolates derived from hippoboscid flies and mosquitoes are most likely also avian trypanosomes infecting birds other than the studied raptors. Analysis of the kinetoplast, that has features characteristic for the avian trypanosomes (minicircle size; dimensions of the kinetoplast disc), provided further evidence for the identification of vectors. It is suggested that all trypanosomes isolated from raptors included in this study belong to the T. avium complex and are transmitted by the ornithophilic simuliids such as Eusimulium securiforme.

Untangling the effects of fire, grazing, and land-use legacies on grassland butterfly communities

Abstract: Many grassland ecosystems are disturbance-dependent, having evolved under the pressures of fire and grazing. Restoring these disturbances can be controversial, particularly when valued resources are thought to be disturbance-sensitive. We tested the effects of fire and grazing on butterfly species richness and population density in an economically productive grassland landscape of the central U.S. Three management treatments were applied: (1) patch-burn graze—rotational burning of three spatially distinct patches within a pasture, and moderately-stocked cattle grazing (N = 5); (2) graze-and-burn—burning entire pasture every 3 years, and moderately-stocked cattle grazing (N = 4); and (3) burn-only—burning entire pasture every 3 years, but no cattle grazing (N = 4). Butterfly abundance was sampled using line transect distance sampling in 2008 and 2009, with six 100-m transects per pasture. Butterfly species richness did not respond to management treatment, but was positively associated with pre-treatment proportion of native plant cover. Population density of two prairie specialists (Cercyonis pegala and Speyeria idalia) and one habitat generalist (Danaus plexippus) was highest in the burn-only treatment, whereas density of one habitat generalist (Cupido comyntas) was highest in the patch-burn graze treatment. Treatment application affected habitat structural characteristics including vegetation height and cover of bare ground. Historic land uses have reduced native plant cover and permitted exotic plant invasion; for some butterfly species, these legacies had a greater influence than management treatments on butterfly density. Conservation of native insect communities in altered grasslands might require native plant restoration in addition to restoration of disturbance processes.

Comparative Study With New Accuracy Metrics for Target Volume Contouring in PET Image Guided Radiation Therapy

Abstract: The impact of positron emission tomography (PET) on radiation therapy is held back by poor methods of defining functional volumes of interest. Many new software tools are being proposed for contouring target volumes but the different approaches are not adequately compared and their accuracy is poorly evaluated due to the ill-definition of ground truth. This paper compares the largest cohort to date of established, emerging and proposed PET contouring methods, in terms of accuracy and variability. We emphasize spatial accuracy and present a new metric that addresses the lack of unique ground truth. Thirty methods are used at 13 different institutions to contour functional volumes of interest in clinical PET/CT and a custom-built PET phantom representing typical problems in image guided radiotherapy. Contouring methods are grouped according to algorithmic type, level of interactivity and how they exploit structural information in hybrid images. Experiments reveal benefits of high levels of user interaction, as well as simultaneous visualization of CT images and PET gradients to guide interactive procedures. Method-wise evaluation identifies the danger of over-automation and the value of prior knowledge built into an algorithm.