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Milwaukee, WI, United States

Boscarino B.T.,Cornell University | Rudstam L.G.,Cornell University | Tirabassi J.,Cornell University | Janssen J.,Great Lakes WATER Institute | Loew E.R.,Cornell University
Limnology and Oceanography | Year: 2010

An understanding of the effect of light on predator-prey interactions in aquatic systems requires the integration of sensory physiology, behavioral ecology, and spatial distributions of predator and prey in the field. Here, we present such an integrative approach to a study on the interactions between the alewife, Alosa pseudoharengus, and the mysid shrimp, Mysis diluviana, (formerly M. relicta) in Lake Ontario at night, when it is unknown whether visual feeding is possible. Visual pigment analyses of alewife rod photoreceptors were used to derive an alewife-specific unit of brightness-the 'alelux' (wavelength of maximum absorbance, λ max 5 505 nm)-which formed the basic unit of light intensity in alewife feeding-rate experiments and field applications. At light levels of 1027 alelux (∼ 10 24.1 lux) and greater in the laboratory, alewives engaged in visual search and strike behaviors and fed at rates that were significantly higher than those under completely dark conditions. Field observations from Lake Ontario showed that light levels at the upper edge of the mysid distribution were within the range of those required for visual feeding in the laboratory on a full moon night, but not on a new moon night. These increased light levels translated into feeding rates that were > 30 times higher on the full moon night, despite a larger degree of spatial separation of the two trophic levels. We hypothesize that observed increased water clarity in Lake Ontario in recent years has led to increased consumption of mysids by alewife at night and associated food-web changes. © 2010, by the American Society of Limnology and Oceanography, Inc.

Wu X.,University of Wisconsin - Milwaukee | Li Y.,University of Wisconsin - Milwaukee | Consi T.R.,Great Lakes WATER Institute
ASME 2010 Dynamic Systems and Control Conference, DSCC2010 | Year: 2010

This paper presents a life extending minimum-time path planning algorithm for legged robots, with application for a six-legged walking robot (hexapod). The leg joint fatigue life can be extended by reducing the constraint on the dynamic radial force. The dynamic model of the hexapod is built with the Newton Euler Formula. In the normal condition, the minimum-time path planning algorithm is developed through the bisecting-plane (BP) algorithm with the constraints of maximum joint angular velocity and acceleration. According to the fatigue life model for ball bearing, its fatigue life increases while the dynamic radial force on the bearing decreases. The minimum-time path planning algorithm is thus revised by reinforcing the constraint of maximum radial force based on the expectation of life extension. A symmetric hexapod with 18 degree-of-freedom is used for simulation study. As a simplified treatment, the magnitudes of dynamic radial force on proximal joints at the pair of supporting legs are set identical to achieve similar degradation rates on each joint bearing and obtain the dynamic radial force on each joint. The simulation results validate the effectiveness of the proposed idea. This scheme can extend the operating life of robot (joint bearing fatigue life) by modifying the joint path only without affecting the primary task specifications. Copyright © 2010 by ASME.

Tomlinson L.M.,Michigan Technological University | Auer M.T.,Michigan Technological University | Bootsma H.A.,Great Lakes WATER Institute | Owens E.M.,Upstate Freshwater Institute
Journal of Great Lakes Research | Year: 2010

A recent review of the Great Lakes Water Quality Agreement has concluded that while controls on phosphorus inputs to Lake Michigan achieved the desired effect in offshore waters, the nearshore region continues to suffer from elevated phosphorus levels. Failure to achieve trophic state goals in the nearshore is manifested in nuisance growth of Cladophora and attendant impacts on property owners, utilities, and the public health and welfare. This study focuses on a site in Lake Michigan near Milwaukee, Wisconsin, where nuisance growth of Cladophora and associated beach fouling occur regularly. A mechanistic model simulating Cladophora growth, suitable for guiding nutrient management in the Great Lakes nearshore, is presented. The model represents an update of the Canale and Auer framework, reflecting current understandings of Cladophora ecology and offering a user-friendly interface making the software more widely available to decision makers. This Great Lakes Cladophora Model (GLCM) is first validated for the Auer/Canale data set collected in 1979 at a site on Lake Huron and then for a data set developed in 2006 for a site on Lake Michigan. Model performance under the strikingly different forcing conditions (depth, light, phosphorus levels) characteristic of these two sites affirms the widespread applicability of the tool. The GLCM is then extended to examine the impacts of ecosystem perturbation (dreissenid colonization) on Cladophora growth and to future approaches to monitoring and management. © 2010 Elsevier B.V. All rights reserved.

Auer M.T.,Michigan Technological University | Tomlinson L.M.,Michigan Technological University | Higgins S.N.,University of Waterloo | Higgins S.N.,University of Wisconsin - Madison | And 3 more authors.
Journal of Great Lakes Research | Year: 2010

Nuisance growth of the attached, green alga Cladophora was considered to have been abated by phosphorus management programs mandated under the Great Lakes Water Quality Agreement. The apparent resurgence of nuisance growth in Lakes Erie, Michigan and Ontario has been linked conceptually to ecosystem alterations engineered by invasive dreissenid mussels (Dreissena polymorpha and Dreissena bugensis). Here, we apply contemporary modeling tools and historical water quality data sets in quantifying the impact of long-term changes in phosphorus loading and dreissenid-mediated changes in water clarity on the distribution and production of Cladophora. It is concluded that reductions in phosphorus loading in the predreissenid period achieved the desired effect, as model simulations were consistent with the biomass declines reported from the early 1970s to the early 1980s. These declines were, however, largely offset by dreisseniddriven changes in water clarity that extended the depth of colonization by Cladophora, increasing total production. We were not able to isolate and quantify the significance of dreissenid mediation of phosphorus cycling using the historical database. Phosphorus management remains the appropriate mechanism for reducing nuisance levels of Cladophora growth. The development of action plans will require an improved understanding of nearshore phosphorus dynamics such as might be obtained through regular monitoring of soluble reactive phosphorus levels, internal phosphorus content and Cladophora biomass in impacted nearshore regions of the Great Lakes. © 2010 Elsevier B.V. All rights reserved.

Boltana S.,Autonomous University of Barcelona | Reyes-Lopez F.,University of Santiago de Chile | Morera D.,Autonomous University of Barcelona | Goetz F.,Great Lakes WATER Institute | MacKenzie S.A.,Autonomous University of Barcelona
BMC Genomics | Year: 2011

Background: Pathogen-associated molecular patterns (PAMPs) are structural components of pathogens such as lipopolysaccharide (LPS) and peptidoglycan (PGN) from bacterial cell walls. PAMP-recognition by the host results in an induction of defence-related genes and often the generation of an inflammatory response. We evaluated both the transcriptomic and inflammatory response in trout (O. mykiss) macrophages in primary cell culture stimulated with DAP-PGN (DAP; meso-diaminopimelic acid, PGN; peptidoglycan) from two strains of Escherichia coli (PGN-K12 and PGN-O111:B4) over time.Results: Transcript profiling was assessed using function-targeted cDNA microarray hybridisation (n = 36) and results show differential responses to both PGNs that are both time and treatment dependent. Wild type E. coli (K12) generated an increase in transcript number/diversity over time whereas PGN-O111:B4 stimulation resulted in a more specific and intense response. In line with this, Gene Ontology analysis (GO) highlights a specific transcriptomic remodelling for PGN-O111:B4 whereas results obtained for PGN-K12 show a high similarity to a generalised inflammatory priming response where multiple functional classes are related to ribosome biogenesis or cellular metabolism. Prostaglandin release was induced by both PGNs and macrophages were significantly more sensitive to PGN-O111:B4 as suggested from microarray data.Conclusion: Responses at the level of the transcriptome and the inflammatory outcome (prostaglandin synthesis) highlight the different sensitivity of the macrophage to slight differences (serotype) in peptidoglycan structure. Such divergent responses are likely to involve differential receptor sensitivity to ligands or indeed different receptor types. Such changes in biological response will likely reflect upon pathogenicity of certain serotypes and the development of disease. © 2011 Boltaña et al; licensee BioMed Central Ltd.

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