Analogical reconstruction of the probability knowledge of Zimbabwean female secondary school students

Abstract

Analogies were used to facilitate reconstructing the probability knowledge of 54 culturally diverse, female, Zimbabwean secondary school students in cases where there were misconceptions in their comprehension of probability. Ten contextually appropriate misconception‐prone target situations were generated, together with their conceptually analogous counterparts, known as source or anchoring situations. The source analogues were designed to draw out those areas where student beliefs agreed with accepted mathematical theory. Students’ responses to the target situations indicated that probability misconceptions were common and that the source analogues were effective in providing anchors for mathematically correct ideas. The participants were interviewed and knowledge reconstruction was attempted using the source analogues. A success rate of 0.88 was achieved. Testing after one month indicated a stability rate of 0.82 for the reconstructed probability knowledge.     

Generation companies decision-making modeling by linear control theory

This paper proposes four decision-making procedures to be employed by electric generating companies as part of their bidding strategies when competing in an ologopolistic market: naïve, forward, adaptive, and moving average expectations. Decision-making is formulated in a dynamic framework by using linear control theory. The results reveal that interactions among all GENCOs affect market dynamics. Several numerical examples are reported, and conclusions are presented.     

Tunable 3D Nanoresonators for Gas‐Sensing Applications

The detection of gas species with high sensitivity is a significant task for fundamental sciences as well as for industrial applications. Similarly, the ongoing trend for device miniaturization brings new challenges for advanced fabrication including on‐demand functionality tuning. Following this motivation, here the additive, direct‐write fabrication of freestanding 3D nanoarchitectures is introduced, which can be brought into mechanical resonance via electric AC fields. Specifically, this study focuses on the 3D nanostructure synthesis, the subsequent determination of Young's modulus, and demonstrates a postgrowth procedure, which can precisely tune the material modulus. As‐fabricated resonators reveal a Young's modulus of 9–13 GPa, which can be increased by a factor greater than 5. Next, the electric readout of the resonance behavior is demonstrated via electric current measurement as an essential element for the resonance sensor applications. Finally, the implications of gas‐physisorption and gas‐chemisorption on the resonance frequencies are studied, representing a proof‐of‐principle for sensing applications by the here presented approach.     

Effects of sea surface temperature accuracy on offshore wind resource assessment using a mesoscale model

Offshore wind simulations were performed with the Weather Research and Forecasting (WRF) model driven by three different sea surface temperature (SST) datasets for Japanese coastal waters to investigate the effect of the SST accuracies on offshore wind simulations. First, the National Centers for Environmental Prediction Final analysis (FNL) (1° × 1° grid resolution) and the Operational Sea Surface Temperature and Sea Ice Analysis (OSTIA) (0.05° × 0.05° grid resolution) datasets were compared with in situ measurements. The results show a decrease in accuracy of these datasets toward the coast from the open ocean. Aiming at an improved accuracy of SST data, we developed a new high‐resolution SST dataset (0.02° × 0.02° grid resolution). The new dataset referred to as MOSST is based on the Moderate Resolution Imaging Spectroradiometer (MODIS) product, provided by the Japan Aerospace Exploration Agency (JAXA). MOSST was confirmed to be more accurate than FNL and OSTIA for the coastal waters. Then, WRF simulations were carried out for 1 year with a 2 km grid resolution and by using the FNL, OSTIA and MOSST datasets. The use of the OSTIA dataset for a WRF simulation was found to improve the accuracy when compared with the FNL dataset, and further improvement was obtained when the MOSST dataset was applied. The sensitivity of wind speed and wind energy density to SST is also discussed. We conclude that the use of an accurate SST is a key factor not only for realistic offshore wind simulations near the surface but also for accurate wind resource assessments at the hub height of wind turbines. Copyright © 2014 John Wiley & Sons, Ltd.     

A Nonlinear Model Combining Pulmonary Mechanics and Gas Concentration Dynamics

To elucidate the various mechanisms by which pulmonary mechanics affect the distribution of gas species throughout the lungs, a multicompartment model relating pressure differences, flows, volumes, and gas species concentrations has been developed. The alveolar regions of the model are nonlinearly elastic and the pressure-flow relation of their associated small airways is volume dependent. Various combinations of parameter values were chosen, including cases in which the model was mechanically uniform (normal) and nonuniform (obstructive). Computer solutions of model equations were obtained for both piecewise-exponential and sinusoidal transpulmonary pressure inputs. Clinical measures of mechanical uniformity and gas concentration homogeneity were evaluated along with unobservable indexes. Results indicate how the distribution of mechanical variables affects the distribution of gas species concentration within the lungs. For the nonuniform (obstructive) model, the gas is distributed more inhomogeneously at higher frequencies and lower lung volumes. The distribution of initial dead space gas to the compartments as well as pendelluft tend to decrease this inhomogeneity. Dynamic compliance for the non-uniform model was frequency dependent at each of the three volume operating points investigated, whereas the semilog nitrogen washout curve was essentially linear for some frequencies and volumes while nonlinear for others. Consequently, inferences about distributions of mechanical parameters and intrapulmonary gas may require that clinical measurements be obtained together at several frequencies and volume operating points.     

Laboratory-scale mirrors for submillimeter wavelengths

A machining procedure based on an elementary concept has been applied successfully to produce metal mirrors suitable for submillimeter wavelengths. Ninety-degree off-axis paraboloidal or ellipsoidal mirror sections may be cut from brass or aluminum by means of a series of predetermined increments on a conventional laboratory lathe. Paraboloidal mirrors with low f-numbers (f/2) made by this technique have been used with good results as part of the collecting optics of a submillimeter-wave heterodyne radiometer.     

Plant growth regulatory activities of artemisinin and its related compounds

Artemisinin, a sesquiterpene lactone produced in the leaves ofArtemisia annua, was evaluated for its phytotoxicity in mono- and dicotyledonous plants. Artemisinin inhibited seed germination, seedling growth, and root induction in all species tested. The concentration of artemisinin required for 50% inhibition ofLemna minor growth was 5 M. Inhibitory plant responses appeared to require the endoperoxide moiety of this compound since similar chemicals without endoperoxide, deoxyartemisinin, arteannuic acid, and arteannuin B, were less phytotoxic. InL. minor, artemisinin and arteannuic acid caused the leakage of proteins into the growth medium, suggesting the site of activity was at the plant cell membrane.