Developing Knowledge Landscapes through Project-Based Learning

The traditional civil engineering-based approach to construction engineering and management education focuses significant attention on core subjects such as scheduling, estimating, and contracts. This paper introduces an alternative approach to this education based on the concepts of project-based learning. Through the introduction of courses developed by the writers, the paper provides a foundation for changing current education approaches from a lecture-based format to a project-based format. In this format, students are challenged with open-ended problems requiring greater application of multiple engineering concepts as well as requiring interaction with outside experts from within the construction industry and related professions. An outline for a project-based learning course is presented with experiences and lessons learned from four implementations of the course. Student responses are presented to indicate the potential benefits of such an approach. This finding is further supported by the introduction of the Knowledge Landscape concept for construction education that emphasizes greater use of context, scope, and multiple intelligences in construction engineering education.     

Threats to cassava production: known and potential geographic distribution of four key biotic constraints

Insect pests and plant diseases reduce cassava yields substantially, posing a threat to food security throughout the developing world. While agricultural scientists have recognized these threats, few assessments of the geographic distribution of cassava pests and diseases have been made at the global scale. The goal of this study is to make such an evaluation for four key biotic constraints to cassava production in developing countries: whiteflies, cassava green mites, cassava mosaic disease and cassava brown streak disease. Occurrence records were obtained from laboratory and biodiversity databases and from the scientific literature. These records were then used in ecological niche models to predict the potential distribution of cassava pests and diseases. The distribution maps were cross validated by holding back 20% of the occurrence records. Potential distribution maps were developed by combining the results of the best ecological niche models. Hotspots for potential cassava pest and disease outbreaks include the Mato Grosso in Brazil, northern South America, the African rift valley, the southern tip of India and much of Southeast Asia, where all four biotic constraints show high potential suitability. Our work highlights how potential geographical shifts in infestation hotspots for several cassava biotic constraints will require intensified monitoring, evaluation and research to prevent yield losses and ensure food security.     

The influence of API concentration on the roller compaction process: modeling and prediction of the post compacted ribbon,granule and tablet properties using multivariate data analysis

Objective: While previous research has demonstrated roller compaction operating parameters strongly influence the properties of the final product, a greater emphasis might be placed on the raw material attributes of the formulation. There were two main objectives to this study. First, to assess the effects of different process variables on the properties of the obtained ribbons and downstream granules produced from the rolled compacted ribbons. Second, was to establish if models obtained with formulations of one active pharmaceutical ingredient (API) could predict the properties of similar formulations in terms of the excipients used, but with a different API.

Materials and methods: Tolmetin and acetaminophen, chosen for their different compaction properties, were roller compacted on Fitzpatrick roller compactor using the same formulation. Models created using tolmetin and tested using acetaminophen. The physical properties of the blends, ribbon, granule and tablet were characterized. Multivariate analysis using partial least squares was used to analyze all data.

Results: Multivariate models showed that the operating parameters and raw material attributes were essential in the prediction of ribbon porosity and post-milled particle size. The post compacted ribbon and granule attributes also significantly contributed to the prediction of the tablet tensile strength.

Conclusions: Models derived using tolmetin could reasonably predict the ribbon porosity of a second API. After further processing, the post-milled ribbon and granules properties, rather than the physical attributes of the formulation were needed to predict downstream tablet properties. An understanding of the percolation threshold of the formulation significantly improved the predictive ability of the models.     

Contact physics of gold microcontacts for MEMS switches

This work presents a study of gold metallic contacts regarding contact resistance, heat dissipation, and surface damage in the normal-force regime of tens to hundreds of μN, which is typical of the contact forces from microactuation. The purpose of this work is to present the micromechanical switch designer with practical information on gold contact phenomena in this force regime, as most work in micrometallic contacts has focused on contact forces greater than 1 mN. Results indicate actuation forces of several hundred μN are required for reliable fully metallic contacts, with resistance and current carrying ability primarily dependent on morphology, thermal management, and nm-depth material properties of the contact electrodes     

Electrosynthesis and characterization of new conducting copolymer films from 1‐naphthol and methyl naphthyl ether

New conducting polymer films have been prepared on platinum electrodes by anodic polymerization of 1‐naphthol in the presence of methyl naphthyl ether (MNE) in MeCN containing 0.1 M LiClO₄. The presence of MNE was found to suppress oligomer formation and significantly affect the physicochemical properties of the polymeric films formed via copolymerization, as confirmed by IR and elemental analysis. In contrast to the autocatalytic polymerization mechanism observed during poly(1‐naphthol) formation, a competitive catalytic‐inhibiting mechanism was found for the copolymer. The copolymer (1:1 and 1:10 1‐naphthol:MNE) showed electrochemical activity similar to that of poly(1‐naphthol). The copolymer films resisted degradation in MeCN effectively and charging–discharging cycles led to doubling of the redox charge after about 20 cycles, while poly(1‐naphthol) films lost 90% of the redox charge under the same conditions. The conductivity of copolymer (1:1) films were 1–2 orders of magnitude lower than that of poly(1‐naphthol). The diffusion coefficients of the charge transfer for the doping–dedoping processes of the copolymer films were slightly lower than for poly(1‐naphthol), but the diffusion coefficients for the redox [Fe(CN)₆]^3−/4− were comparable for both films. © 2000 Society of Chemical Industry     

Effect of thioanisole and trimethylene sulfide on the oxidation and yellowing of methyl linolenate

The effect of thioanisole and trimethylene sulfide on the autoxidation and yellowing of methyl linolenate has been investigated by nuclear magnetic resonance (NMR) and ultraviolet visible spectroscopy, respectively. The progress of autoxidation was followed by measuring the NMR integration of vinylic protons with respect to methoxy protons, which served as the internal standard, as a function of time. The degree of yellowing was determined by measuring the difference in absorbance at 400 nm and 450 nm as a function of time. Both thioanisole and trimethylene sulfide enhanced the autoxidation of methyl linolenate. Inhibition of yellowing was observed only with trimethylene sulfide.     

The influence of peers on young adult substance use.

Data collected from 294 young adults, ages 19 to 25, and both a same- and an opposite-gender best friend or mate across 3 annual assessments were analyzed to examine the similarity to and influence of the peer on the young adult's substance use. The authors found similarity across time between both peers and the young adult in cigarette use, alcohol use, binge drinking, and, in most cases, marijuana use. In prospective analyses, peer use predicted young adult cigarette use, binge drinking, and problem use by the young adults. Results were generally consistent across gender and for both same- and opposite-gender peers. Findings emphasize peer influence contribution to young adult substance use and suggest the design of interventions that involve both young adults and their peers. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Mixed-effects logistic regression for estimating transitional probabilities in sequentially coded observational data.

This article demonstrates the use of mixed-effects logistic regression (MLR) for conducting sequential analyses of binary observational data. MLR is a special case of the mixed-effects logit modeling framework, which may be applied to multicategorical observational data. The MLR approach is motivated in part by G. A. Dagne, G. W. Howe, C. H. Brown, & B. O. Muthén (2002) advances in general linear mixed models for sequential analyses of observational data in the form of contingency table frequency counts. The advantage of the MLR approach is that it circumvents obstacles in the estimation of random sampling error encountered using Dagne and colleagues' approach. This article demonstrates the MLR model in an analysis of observed sequences of communication in a sample of young adult same-sex peer dyads. The results obtained using MLR are compared with those of a parallel analysis using Dagne and colleagues' linear mixed model for binary observational data in the form of log odds ratios. Similarities and differences between the results of the 2 approaches are discussed. Implications for the use of linear mixed models versus mixed-effects logit models for sequential analyses are considered. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

MPP+ induced substantia nigra degeneration is attenuated in nNOS knockout mice

Differential scanning calorimetry was used to characterize thermal events associated with freezing and melting of suspensions and extracts of Panagrolaimus davidi, an Antarctic nematode which can survive intracellular freezing. Nematode suspensions produced a single freezing exotherm with a shoulder on the peak representing the freezing of the nematodes. A shoulder on the peak of melting endotherms indicates the melting of the nematodes and of the water surrounding them. Exotherms were also detected from individual nematodes mounted in liquid paraffin. The freezing of nematodes was very rapid and in marked contrast to that of freezing-tolerant insects and vertebrates, which take hours or days to freeze. Eighty-two percent of the nematodes' body water froze. High levels of survival were obtained in nematodes exposed to temperatures down to -40 degrees C. No additional thermal events were observed after the freezing event and before the melting of samples cooled to -40 degrees C, indicating no changes in the proportion of body water frozen. Ice nucleating activity is present in nematode suspensions but not in supernatants from nematode extracts. No thermal hysteresis activity was detected in nematode extracts.     

Unraveling the mystery of cognitive changes in old age: correlation of neuropsychological evaluation with neuropathological findings in the extreme old

In order to understand what cognitive changes can be expected with aging versus those caused by disease, the New England Centenarian Study examined correlations between neuropsychological evaluation and neuropathological studies of centenarian subjects. Sixty-nine subjects were administered an extensive neuropsychological test battery designed for centenarians. Six brain donors from this group have subsequently died, and neuropathological studies of their brains have been performed to determine the presence of Alzheimer's disease (AD) and other pathological states. Of these six centenarians, three subjects had Clinical Dementia Rating scores of 0 and no dementia on neuropsychological testing, and subsequent neuropathology showed very limited AD changes. In fact, despite a range of neuropsychological findings, none of the subjects in this series met neuropathological criteria for a diagnosis of definite AD. Findings suggest that dementia is not inevitable with aging and that dementia in this age group is surprisingly often not attributable to AD.