On the least restrictive control for collision avoidance of two unicycles

We give an explicit analytical characterization of the least restrictive control for collision avoidance of two unicycles. The controller is proved to be least restrictive using viability theory. Copyright © 2006 John Wiley & Sons, Ltd.     

Thin optic constraint

The success of using thin substrates in various fields has urged researchers to further study the possibilities of improving the technology for future applications. For example, the high surface-area-to-weight ratio and strength of sheet glass allow flat-panel display technology to result in high-definition televisions that can be hung on walls like paintings. Sheet glass is also the prime candidate for grazing-incidence foil-optic X-ray telescopes, such as the segmented mirror approach considered for the NASA C onstellation X mission, where cost limitations necessitate lightweight substrates.The effects of different parameters present during the metrology of thin optics, such as gravity, frictional and thermal forces, are identified and analyzed. These forces alter the optic’s surface topography by tens of microns depending on how the optics are manipulated and constrained. This renders metrology and thus surface shaping process results inconclusive.A metrology truss utilizing monolithic flexures to kinematically constrain thin optics during metrology is designed. This device mitigates the effects of the forces mentioned above that are induced on the thin sheet while being mechanically constrained, thus significantly improving the repeatability of the optic surface map measurements.     

QUALICON: Computer-Based System for Construction Quality Management

This paper describes a computer-based system for construction quality management. The system tasks are derived from the elements of ISO 9001 standard and designed to integrate with other computer-aided project management functions. They can assist management in (1) the definition of requirements/criteria for design, construction, and quality management; (2) the development of inspection and test plans; (3) the tracking of actual inspection/test results; (4) the verification of their conformance to defined criteria; (5) the documentation of past experience in the form of standard templates for assisting the tasks involved; and (6) the generation of reports. A model was defined for representing the information used in the system tasks. The central role of the inspection and test plan representation was exploited to associate to construction components and processes, relevant inspections/tests, requirements/criteria, actual results, and nonconformance analyses. Templates were devised to enable the reuse of predefined packages of information, which recur from project to project. The developed system will render the assisted quality management tasks more effective. Its use was tested on data from different construction domains.     

Predicting workplace aggression: A meta-analysis.

The authors conducted a meta-analysis of 57 empirical studies (59 samples) concerning enacted workplace aggression to answer 3 research questions. First, what are the individual and situational predictors of interpersonal and organizational aggression? Second, within interpersonal aggression, are there different predictors of supervisor- and coworker-targeted aggression? Third, what are the relative contributions of individual (i.e., trait anger, negative affectivity, and biological sex) and situational (i.e., injustice, job dissatisfaction, interpersonal conflict, situational constraints, and poor leadership) factors in explaining interpersonal and organizational aggression? Results show that both individual and situational factors predict aggression and that the pattern of predictors is target specific. Implications for future research are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Adults' Age-Related Differences in Adaptivity of Strategy Choices: Evidence From Computational Estimation.

Four experiments document adults' age-related changes in computational estimation performance and in adaptivity of strategy choices (i.e., the ability to choose the most precise strategy on each trial). Young and older adults were asked to provide estimates of 2-by-2-digit multiplication problems (e.g., 43 X 78) under varying conditions of speed and accuracy emphasis. The main findings showed that (a) older adults provided less accurate estimates and took more time to estimate, especially on the most difficult problems or when using harder strategies; (b) young and older adults had similar strategy preferences; and (c) older adults chose estimation strategies less adaptively than young adults. Implications of these findings for understanding strategic changes during adulthood in a wide variety of cognitive domains are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dipolar versus octupolar triphenylamine-based fluorescent organic nanoparticles as brilliant one- and two-photon emitters for (bio)imaging

Two related triphenylamine-based dipolar and octupolar fluorophores are used to prepare aqueous suspensions of fluorescent organic nanoparticles (FONs) via the reprecipitation method. The obtained spherical nanoparticles (30-40 nm in diameter) are fluorescent in aqueous solution (up to 15% fluorescence quantum yield) and exhibit extremely high one- and two-photon brightness, superior to those obtained for quantum dots. Despite the two chromophores showing similar fluorescence in solution, the fluorescence of FONs made from the octupolar derivative is significantly red-shifted compared to that generated by the dipolar FONs. In addition, the maximum two-photon absorption cross section of the FONs made from the octupolar derivative is 55% larger than that of the dipolar derivative FONs. The experimental observations provide evidence that the different molecular shape (rodlike versus three-branched) and charge distribution (dipolar versus octupolar) of the two chromophores strongly affect the packing inside the nanoparticles as well as their spectroscopic properties and colloidal stability in pure water. The use of these FONs as probes for biphotonic in-vivo imaging is investigated on Xenopus laevis tadpoles to test their utilization for angiography. When using FONs made from the octupolar dye, the formation of microagglomerates (2-5 μm scale) is observed in vivo, with subsequent lethal occlusion of the blood vessels. Conversely, the nanoparticles of the dipolar dye allow acute imaging of blood vessels thanks to their suitable size and brightness, while no toxic effect is observed. Such a goal cannot be achieved with the dissolved dye, which permeates the vessel walls.     

Characterization of zirconia- and niobia-silica mixture coatings produced by ion-beam sputtering

ZrO2-SiO2 and Nb2O5-SiO2 mixture coatings as well as those of pure zirconia (ZrO2), niobia (Nb2O5), and silica (SiO2) deposited by ion-beam sputtering were investigated. Refractive-index dispersions, bandgaps, and volumetric fractions of materials in mixed coatings were analyzed from spectrophotometric data. Optical scattering, surface roughness, nanostructure, and optical resistance were also studied. Zirconia-silica mixtures experience the transition from crystalline to amorphous phase by increasing the content of SiO2. This also results in reduced surface roughness. All niobia and silica coatings and their mixtures were amorphous. The obtained laser-induced damage thresholds in the subpicosecond range also correlates with respect to the silica content in both zirconia- and niobia-silica mixtures.     

Rapid and accurate bacterial identification in probiotics and yoghurts by MALDI-TOF mass spectrometry

Probiotic food is manufactured by adding probiotic strains simultaneously with starter cultures in fermentation tanks. Here, we investigate the accuracy and feasibility of matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS) for bacterial identification at the species level in probiotic food and yoghurts. Probiotic food and yoghurts were cultured in Columbia and Lactobacillus specific agar and tested by quantitative real-time PCR (qPCR) for the detection and quantification of Lactobacillus sp. Bacterial identification was performed by MALDI-TOF analysis and by amplification and sequencing of tuf and 16S rDNA genes. We tested 13 probiotic food and yoghurts and we identified by qPCR that they presented 10(6) to 10(7) copies of Lactobacillus spp. DNA/g. All products contained very large numbers of living bacteria varying from 10(6) to 10(9) colony forming units/g. These bacteria were identified as Lactobacillus casei, Lactococcus lactis, Bifidobacterium animalis, Lactobacillus delbrueckii, and Streptococcus thermophilus. MALDI-TOF MS presented 92% specificity compared to the molecular assays. In one product we found L. lactis, instead of Bifidus spp. which was mentioned on the label and for another L. delbrueckii and S. thermophilus instead of Bifidus spp. MALDI-TOF MS allows a rapid and accurate bacterial identification at the species level in probiotic food and yoghurts. Although the safety and functionality of probiotics are species and strain dependent, we found a discrepancy between the bacterial strain announced on the label and the strain identified. Practical Application: MALDI-TOF MS is rapid and specific for the identification of bacteria in probiotic food and yoghurts. Although the safety and functionality of probiotics are species and strain dependent, we found a discrepancy between the bacterial strain announced on the label and the strain identified.