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We monitored the recruitment of young-of-year zebra mussels (Dreissena polymorpha (Pallas, 1771)) each autumn at 13 locations within four river reaches along the length (100 km) of the Rideau River, starting in 1990, the year of its discovery in that river, until 2015. Sampling was conducted on bottom structures of locks or on seasonally exposed substrate during autumn drawdowns conducted by Rideau Canal staff. Twenty-six years of monitoring zebra mussels in that river revealed a distinct and persistent upstream--downstream pattern, with highest densities occurring in the two downstream reaches. A 'lake effect' was observed at Long Reach, where veligers have ideal conditions for larval development. Highest densities occurred in the mid-1990s, comparable with those reported in the Laurentian Great Lakes during peak invasion (200 000 to 500 000+ mussels/[m.sup.2]). Although the most upstream reaches of the river had low recruitment rates and low densities initially (0.01 to 10 mussels/[m.sup.2]), annual recruitment progressively increased to higher values (10 to 1000+ mussels/[m.sup.2]) because more veligers from the Rideau Lakes and the river headwaters were produced and drifted into the system. This study is unique because it provides a thorough understanding of the 26 years of invasion history of the zebra mussel in a small river system. Key words: zebra mussel, Dreissena polymorpha, invasion, long-term monitoring, larval settlement, recruitment, impoundment, Rideau River. Nous avons effectué des suivis automnaux annuels du recrutement de jeunes moules zébrées (Dreissena polymorpha (Pallas, 1771)) dans 13 sites répartis dans quatre tronçons le long des 100 km de la rivière Rideau, de 1990 (année de la découverte de l'espèce dans la rivière) à 2015. L'échantillonnage a été réalisé sur des structures au fond d'écluses ou sur des substrats exposés durant des abaissements du niveau d'eau effectués à l'automne par le personnel du canal Rideau. Ces suivis sur 26 ans révèlent un net contraste entre l'amont et l'aval, les plus hautes densités étant observées dans les deux tronçons plus en aval de la rivière. Un << effet de lac >> est observé dans le tronçon Long Reach, où les conditions sont idéales pour le développement des véligères. Les plus fortes densités, observées au milieu des années 1990, sont semblables à celles qui étaient signalées pour les Grands Lacs au plus fort de l'envahissement (de 200 000 à plus de 500 000 moules/[m.sup.2]). Si les tronçons les plus en amont de la rivière présentaient initialement de faibles taux de recrutement et de faibles densités (de 0,01 à 10 moules/[m.sup.2]), le recrutement annuel a augmenté graduellement (pour atteindre de 10 à plus de 1000 moules/[m.sup.2]) avec l'arrivée par dérive de véligères provenant des lacs Rideau et des eaux d'amont de la rivière. Cette étude est unique puisqu'elle fait la lumière sur l'histoire de l'envahissement de la moule zébrée dans une petite rivière sur une période de 26 ans. Mots-clés: moule zébrée, Dreissena polymorpha, invasion, surveillance à long terme, fixation larvaire, recrutement, barrages, rivière Rideau., Introduction In North America, the first specimens of the invasive zebra mussel, Dreissena polymorpha (Pallas, 1771) (Bivalvia, Dreissenidae), were reported in the Laurentian Great Lakes, in 1986 in Lake Erie [...]

Contrast enhanced ultrasound imaging provides a real-time tool for evaluating vasculature in the liver. Primary liver cancer is known to be perfused exclusively by blood from the hepatic artery, whereas normal liver is also supplied by the portal vein. Visual separation of two different phases of enhancement from the independent feeding vessels is important for diagnosis but remains a challenge. This paper presents a method of using factor analysis for extracting distinct time-intensity curves. A key component to this extraction is the clustering of measured bolus curves and their projection onto a positivity domain to obtain nonnegative curves. This technique provides complementary images representing spatial loadings on each curve. As little as 1% of the data is required to contain unmixed signals to extract time-intensity curves that correlate well with true curves. A method of combining this information to display a regional hepatic perfusion image is proposed, and results are tested on a set of 10 patients. Region of interest analysis suggests it is possible to detect changes in the hepatic perfusion index of liver lesions relative to normal liver parenchyma using contrast ultrasound. Index Terms--Factor analysis, hepatic perfusion index, microbubbles, ultrasound.

Research demonstrates that prodissoconch of the sea and bay mussels exhibit morphological differences retained through settlement of the post metamorphic juveniles on the benthos. Data suggest that such morphological traits coupled with genome analysis accurately distinguish the two types of mussels, which coexist in the west coast of North America.

Background: Despite its importance for acute stroke management, little is known about the underlying pathophysiology when patients with acute stroke are classified using clinical methods. Objective: To examine the relation [...]