583 research outputs found
The potential impact of CT-MRI matching on tumor volume delineation in advanced head and neck cancer
To study the potential impact of the combined use of CT and MRI scans on the Gross Tumor Volume (GTV) estimation and interobserver variation. Four observers outlined the GTV in six patients with advanced head and neck cancer on CT, axial MRI, and coronal or sagittal MRI. The MRI scans were subsequently matched to the CT scan. The interobserver and interscan set variation were assessed in three dimensions. The mean CT derived volume was a factor of 1.3 larger than the mean axial MRI volume. The range in volumes was larger for the CT than for the axial MRI volumes in five of the six cases. The ratio of the scan set common (i.e., the volume common to all GTVs) and the scan set encompassing volume (i.e., the smallest volume encompassing all GTVs) was closer to one in MRI (0.3-0.6) than in CT (0.1-0.5). The rest volumes (i.e., the volume defined by one observer as GTV in one data set but not in the other data set) were never zero for CT vs. MRI nor for MRI vs. CT. In two cases the craniocaudal border was poorly recognized on the axial MRI but could be delineated with a good agreement between the observers in the coronal/sagittal MRI. MRI-derived GTVs are smaller and have less interobserver variation than CT-derived GTVs. CT and MRI are complementary in delineating the GTV. A coronal or sagittal MRI adds to a better GTV definition in the craniocaudal directio
Mortality of Metarhizium anisopliae-infected wireworms (Coleoptera: Elateridae) and feeding on wheat seedlings are affected by wireworm weight
Movement of Ericaphis fimbriata (Hemiptera: Aphididae) apterae on blueberry
Blueberry scorch Virus is a new and important pathogen of blueberry in British Columbia, Canada of which the blueberry-infesting aphid Ericaphis fimbriata is a known Vector. In a study of the movement of apterous E. fimbriata, significantly more aphids fell when one ladybird beetle was added to E. fimbriata infested blueberry branches than when zero, two, or four were added. Similar numbers of aphids fell in the presence or absence of beetles at low aphid density (10-30 aphids per terminal), but more fell in the presence of beetles at high aphid density (50-70 aphids per terminal). The time taken for aphids to move a minimum distance of 60 cm off infested plants onto uninfested plants decreased with increasing aphid density which has important implications for the spread of the Virus
Mortality of Metarhizium anisopliae-infected wireworms (Coleoptera: Elateridae) and feeding on wheat seedlings are affected by wireworm weight
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Mortality of five wireworm species (Coleoptera: Elateridae), following topical application of clothianidin and chlorpyrifos
Five Wireworrn species (Agriotes obscurus, A. sputator, Limonius canus, Ctenicera destructor, and C. pruinina) were exposed to clothianidin and chlorpyrifos at various concentrations using a Potter Spray Tower to compare larval susceptibilities to these compounds. Wireworms were stored in containers with soil at 15 °C after insecticide exposure, and their post-application health was evaluated weekly for up to 140 days. Where possible, LC50, LC90, LT50, and LT90 values were calculated and the LC90 and LT90 values of chemical concentrations compared between species. Considerable differences in susceptibility to both chlorpyrifos and clothianidin were observed among species, with the LC90 of L. canus exposed to clothianidin being significantly higher than A. obscurus or A. sputator. Similarly, while the LC50 of A. sputator exposed to chlorpyrifos was similar to that of C. pruinina and A. obscurus assayed in previous studies (0.05, 0.10, 0.10%, respectively), there was low (12.5%) mortality of L. canus at the highest concentration tested (0.15%). There were considerable differences in the survival of various wireworm species after exposure to clothianidin at 0.15%, with the LT90 of L. canus (66.5 days) similar to those of C. pruinina and C. destructor (52.5, 59.5 days, respectively), but much shorter than those for A. obscurus or A. sputator (122.5, 115.5 days, respectively). Considerable differences in the induction of and recovery from morbidity induced by the chemicals were observed among species. Most larvae of A. sputator and A. obscurus exposed to chlorpyrifos were moribund before C. prumina larvae (4, 7, 42 days after exposure, respectively). Most (proportion = 0.86) larvae of L. canus recovered from morbidity induced by chlorpyrifos, but a high proportion (>08) of moribund A. sputator, A. obscurus, and C. pruinina died. Larvae of C. destructor and C. pruinina which were moribund after exposure to clothianidin at 0.15% died or recovered sooner than larvae of L. canus and A. obscurus. Together these results suggest that the efficacy of both clothianidin and chlorpyrifos for wireworm control in the field are affected by the wireworm species present
Convex Structuring Element Decomposition for Single Scan Binary Mathematical Morphology
International audienceThis paper presents a structuring element decomposition method and a corresponding morphological erosion algorithm able to compute the binary erosion of an image using a single regular pass whatever the size of the convex structuring element. Similarly to classical dilation-based methods, the proposed decomposition is iterative and builds a growing set of structuring elements. The novelty consists in using the set union instead of the Minkowski sum as the elementary structuring element construction operator. At each step of the construction, already-built elements can be joined together in any combination of translations and set unions. There is no restrictions on the shape of the structuring element that can be built. Arbitrary shape decompositions can be obtained with existing genetic algorithms with an homogeneous construction method. This paper, however, addresses the problem of convex shape decomposition with a deterministic method
Efficacy of diamide, neonicotinoid, pyrethroid, and phenyl pyrazole insecticide seed treatments for controlling the sugar beet wireworm, Limonius californicus (Coleoptera: Elateridae), in spring wheat
Four classes of insecticide applied on seed were evaluated for managing high populations of the sugar beet wireworm, Limonius californicus (Coleoptera: Elateridae), in spring wheat in southern Alberta, Canada. Three separate field trials were conducted, and assessments made for stand protection, yield, and wireworm survival. Imidacloprid and thiamethoxam applied at 10–30 g AI and cyantraniliprole applied at 10–40 g AI provided initial stand protection, but did not protect seedlings until harvest and did not decrease wireworm populations. λ-cyhalothrin applied at 30 g AI provided stand protection that persisted until harvest, but yields were considerably lower than observed in fipronil treatments and there was little (23%) decrease in populations relative to controls. Fipronil applied at 0.6, 1.0, and 5.0 g AI, either singly or in blend with thiamethoxam at 10 g AI, provided stand protection until harvest and significantly reduced numbers of wireworms larger than 10 mm (range: 74–96%). Very low numbers of small (<11 mm) wireworms were observed in all trials. These results are compared to data from laboratory and field studies for this and other wireworm species. The relation between crop stand protection and wireworm mortality, the potential of insecticide blends, and the importance of seed type, wireworm species, and activity periods for managing wireworms with seed treatments are discussed
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