Cyanobacterial blooms in the central basin of Lake Erie: Potentials for cyanotoxins and environmental drivers

Lake Erie western basin (WB) cyanobacterial blooms are a yearly summer occurrence; however, blooms have also been reported in the offshore waters of the central basin (CB), and very little is known about what drives these blooms or their potential for cyanobacterial toxins. Cyanobacteria Index was quantified using MODIS and MERIS data for the CB between 2003 and 2017, and water samples were collected between 2013 and 2017. The goals were to 1) quantify cyanobacteria, 2) determine environmental drivers of CB blooms, and 3) determine the potential for cyanobacterial toxins in the CB. Dolichospermum (Anabaena) occurred in the CB during July before the onset of the WB bloom, and then in August and September, the cyanobacteria community shifted towards Microcystis. The largest Dolichospermum blooms (2003, 2012, 2013, and 2015) were associated with reduced water clarity (Secchi disk depth?<?4?m), whereas large CB Microcystis blooms (2011 and 2015) were associated with large WB blooms. Dolichospermum blooms occurred in high nitrate concentrations (>20?μmol/L) and high nitrogen-to?phosphorus ratios (>100), which indicate nutrient concentrations or ratios did not select for Dolichospermum. Additionally, the sxtA gene, but not mcyE or microcystins, were detected in the CB during July 2016 and 2017. The mcyE gene and microcystins were detected in the CB during August 2016 and 2017. The results indicate the CB's potential for cyanotoxins shifts from saxitoxins to microcystins throughout the summer. Continued monitoring of cyanobacteria and multiple cyanobacterial toxins is recommended to ensure safe drinking water for CB coastal communities.     

The Design of a New Policy Model to Support Ontology-Driven Reasoning for Autonomic Networking

The purpose of autonomic networking is to manage the business and technical complexity of networked components and systems. However, the lack of a common lingua franca makes it impossible to use vendor-specific network management data to ascertain the state of the network at any given time. Furthermore, the tools used to analyze management data, which include information and data models, ontologies, machine learning algorithms, and policy languages, are all different, and hence require different data in different formats. This paper describes a new version of the Directory Enabled Networks next generation (DEN-ng) policy model, which is part of the FOCALE autonomic network architecture. This new policy model has been built using three guiding principles: (1) the policy model is rooted in information models, so that it can govern managed entities, (2) the model is expressly constructed to facilitate the generation of ontologies, so that reasoning about policies constructed from the model may be done, and (3) the model is expressly constructed so that a policy language can be developed from it.     

A Nanoindentation Study of the Plastic Deformation and Fracture Mechanisms in Single-Crystalline CaFe<Subscript>2</Subscript>As<Subscript>2</Subscript>

The plastic deformation and fracture mechanisms in single-crystalline CaFe₂As₂ has been studied using nanoindentation and density functional theory simulations. CaFe₂As₂ single crystals were grown in a Sn-flux, resulting in homogeneous and nearly defect-free crystals. Nanoindentation along the [001] direction produces strain bursts, radial cracking, and lateral cracking. Ideal cleavage simulations along the [001] and [100] directions using density functional theory calculations revealed that cleavage along the [001] direction requires a much lower stress than cleavage along the [100] direction. This strong anisotropy of cleavage strength implies that CaFe₂As₂ has an atomic-scale layered structure, which typically exhibits lateral cracking during nanoindentation. This special layered structure results from weak atomic bonding between the (001) Ca and Fe₂As₂ layers.     

New high performance two-component wood coatings comprised of a hydroxy functional acrylic emulsion and a water-dispersible polysiocyanate

Statistical methods were used to develop hydroxy functional acrylic emulsions for use with a water-dispersible polyisocyanate crosslinker. The resulting two-component waterborne coating systems were optimized for kitchen cabinet and office furniture applications. Key performance criteria included appearance and aesthetics, pot life, print and mar resistance, and chemical resistance involving both Kitchen Cabinet Manufacturers’ Association (KCMA) and office furniture requirements. Statistical analysis revealed several strong correlations between acrylic emulsion hydroxy level, particle size, composition T_g, polymerization process and wood coating performance. For example, smaller acrylic emulsion particle size was found to yield many performance benefits with few detriments. Coating formulation variables were also found to be significant. Ultimate coating hardness increased with water-dispersible polyisocyanate level, yet early hardness readings correlated negatively with water-dispersible polyisocyanate level. Plasticization and crosslinking effects were thought to be responsible. A higher ethylene glycol monbutyl ether (EB) coalescent level was found to correlate negatively with coating hardness, suggesting a reaction between the EB hydroxyl group and the water-dispersible polyisocyanate, resulting in plasticization of the coating. Coatings and Colorants Div., 100 Bayer Rd., Pittsburgh, PA 15205-9741 Performance Materials Div., 9921 Brecksville Rd., Brecksville, OH 44141-3259.     

The effects of mathematics instruction using spatial temporal cognition on teacher efficacy and instructional practices

This paper examined the effects of an instructional approach known as Spatial Temporal Mathematics (ST Math) on teacher beliefs about mathematics teaching. Participants were 339 elementary teachers teaching grades 2–5 who were randomly assigned to a control or treatment group. Hierarchical linear modeling was used to determine the effects of the intervention on self-efficacy, outcome expectancy, and instructional practices using scientific reasoning. While the treatment did not yield significant effects in teacher outcomes, our secondary analysis indicated that time on ST Math and the integration of ST Math into daily instructions were positively associated with teacher efficacy and instructional practices using scientific reasoning. Implications of the results on teacher beliefs about mathematics teaching are discussed.