Multimodal plan representation for adaptable BML scheduling

Natural human interaction is characterized by interpersonal coordination: interlocutors converge in their speech rates, smoothly switch speaking turns with virtually no delay, provide their interlocutors with verbal and nonverbal backchannel feedback, wait for and react to such feedback, execute physical tasks in tight synchrony, etc. If virtual humans are to achieve such interpersonal coordination they require very flexible behavior plans that are adjustable on-the-fly. In this paper we discuss how such plans are represented, maintained and constructed in our BML realizer Elckerlyc. We argue that behavior scheduling for Virtual Humans can be viewed as a constraint satisfaction problem, and show how Elckerlyc uses this view in its flexible behavior plan representation that allows one to make on-the-fly adjustments to behaviors while keeping the specified constraints between them intact.     

Distinguishing between the partial-mapping preparation hypothesis and the failure-to-engage hypothesis of residual switch costs.

Lien, Ruthruff, Remington, & Johnston (2005) reported residual switch cost differences between stimulus–response (S–R) pairs and proposed the partial-mapping preparation (PMP) hypothesis, which states that advance preparation will typically be limited to a subset of S–R pairs because of structural capacity limitations, to account for these differences. Alternatively, the failure-to-engage (FTE) hypothesis does not allow for differences in probability of advance preparation between S–R pairs within a set; it accounts for residual switch cost differences by assuming that benefits of advance preparation may differ between S–R pairs. Three Experiments were designed to test between these hypotheses. No capacity limitations of the type assumed by the PMP hypothesis were found for many participants in Experiment 1. In Experiments 2 and 3, no evidence was found for the dependency of residual switch cost differences between S–R pairs on response-stimulus interval that is predicted by the PMP hypothesis. Mixture-model analysis of reaction times distributions in Experiment 3 provided strong support for the FTE hypothesis over the PMP hypothesis. Simulation studies with a computational implementation of the FTE hypothesis showed that it is able to account in great detail for the results of the present study. Together, these results provide strong evidence against the PMP hypothesis and support the FTE hypothesis that advance preparation probabilistically fails or succeeds at the level of the task set. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Assessment of maize yield gap and major determinant factors between smallholder farmers in the Dedza district of Malawi

This study explored the effect of soil nutrient status, agronomic practices and socio-economic factors on maize yield attained by smallholder farmers in the Dedza District of Malawi. Results show that maize yield ranged between 0.4 and 12 t ha^?1 with a mean value of 4.1 t ha^?1. Observed high yields (>8.0 t ha^?1) were associated with households using improved varieties combined with improved management practices such as NPK, urea and animal manure. With regards to soil factors, boron (B) and nitrogen (N) which are critically deficient in the area were significantly (β = 21.1, p < 0.01) associated with maize yield increase. From agronomic factors, weeds, seed spacing, plant density and fertilizer application played significant role in maize yield. Weed rating inversely impacted yield (β = ?0.5; p < 0.001) where fields with the lowest weed rating had the highest yield (4.6 t ha^?1) than those with the highest rating (2.3 t ha^?1). Socio-economic factors such as household wealth, household members with off-farm employment, number of years the household head has been involved in farming decision making, access to agricultural advice and group membership also influenced agronomic practices and resulted in yield gap. Household wealth and off-farm employment contributed to increased yield while household head experience in farming had negative impact. Extension service impacted yield negatively which can be attributed to the low extension worker to farmer ratio. The study demonstrated that closing yield gap in maize mixed farming systems requires integrated approach to addressing agronomic, biophysical and socio-economic constraints.     

Dependence of the electrical conductivity and elastomeric properties on sample preparation of blends of polyaniline and natural rubber

Blend films (free‐standing) containing 20% in volume of polyaniline (PANI) in 80% of natural rubber (NR) were fabricated by casting in three different ways: (1) adding PANI‐EB (emeraldine base) dissolved in N‐methyl‐2‐pyrrolidone (NMP) to the latex (NRL), (2) adding PANI‐EB dissolved in m‐cresol to NR dissolved in xylol (NRD), (3) overlaying the surface of a pure NR cast film with a PANI layer grown by in situ polymerization (NRO). All the films were immersed into HCl solution to achieve the primary doping (protonation) of PANI before the characterization. The main goal here was to investigate the elastomeric and electrical conductivity properties for each blend, which may be applied as pressure and deformation sensors in the future. The characterization was carried out by optical microscopy, dc conductivity, vibrational spectroscopy (infrared absorption and Raman scattering), thermogravimetry analysis (TGA), differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA), and tensile stress–strain curves. The results suggest that the NRL blend is the most suitable in terms of mechanical and electrical properties required for applications in pressure and deformation sensors: a gain of conductivity without losing the elastomeric property of the rubber. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1498–1503, 2005     

Principles in the Evolutionary Design of Digital Circuits—Part II

In a previous work it was argued that by studying evolved designs of gradually increasing scale, one might be able to discern new, efficient, and generalisable principles of design. These ideas are tested in the context of designing digital circuits, particularly arithmetic circuits. This process of discovery is seen as a principle extraction loop in which the evolved data is analysed both phenotypically and genotypically by processes of data mining and landscape analysis. The information extracted is then fed back into the evolutionary algorithm to enhance its search capabilities and hence increase the likelihood of identifying new principles which explain how to build systems which are too large to evolve.     

Use of X-ray microtomography to study the homogeneity of carbon nanotube aqueous suspensions and carbon nanotube/polymer composites

X-ray microtomography was used to study the stability and homogeneity of concentrated carbon nanotube (CNT) aqueous suspensions and CNT/resorcinol–formaldehyde gel composites. Various CNT distribution states were achieved by modifying the CNT concentration, sonication time and resting time. X-ray microtomography is able to discriminate between zones with different CNT concentration levels and can be used as a non-destructive and fast tool to characterize the homogeneity of suspensions and composite systems at the micron scale.     

Solitary wave trains in granular chains: experiments,theory and simulations

The features of solitary waves observed in horizontal monodisperse chain of barely touching beads not only depend on geometrical and material properties of the beads but also on the initial perturbation provided at the edge of the chain. An impact of a large striker on a monodisperse chain, and similarly a sharp decrease of bead radius in a stepped chain, generates a solitary wave train containing many single solitary waves ordered by decreasing amplitudes. We find, by simple analytical arguments, that the unloading of compression force at the chain edge has a nearly exponential decrease. The characteristic time is mainly a function involving the grains’ masses and the striker mass. Numerical calculations and experiments corroborate these findings.     

Trace metal concentration in water and sediments of satellite lakes within Lake Victoria (Kenya) basin

Lakes Kanyaboli, Sare and Namboyo are three important freshwater satellite lakes in the northern region of the Lake Victoria (Kenya) basin. Lake Simbi, a small alkaline -saline crater-lake is located near the southern shoreline of the Nyanza Gulf of Lake Victoria. The three freshwater lakes provide unique aquatic habitats for the important indigenous fish species and other aquatic biodiversity, as well as serving as water resources for the surrounding communities. Surface and sediment samples were collected and examined to characterize these lake systems. Metal partitioning among the various defined geochemical phases also was determined. Based on the measured concentrations, the satellite lake waters are relatively uncontaminated with regard to Al (aluminium), manganese (Mn), zinc (Zn), copper (Cu) and chromium (Cr). Levels of most elements were below detection limits, as well as being well below the desirable drinking water guideline values proposed by the World Health Organization. The exception was the elevated iron (Fe) contents (>300 μg L⁻¹). The sediments exhibited a relatively low level of contamination with regard to heavy metals. The mean values of the measured metals in the sediments were compared to levels in adjacent Lake Victoria. The study results from these poorly-studied, and relatively unperturbed ecosystems, compared to the main body of lake Victoria, highlight their importance as conservation areas, despite the small-scale fishery activity, potential threats from human activities and their sensitivity to fluctuating environmental conditions.     

Thermal inkjet printing of polyaniline on paper

The development of organic devices requires the fabrication of thin films, and inkjet printing has been shown to be a suitable method to reach this goal. This work describes the printing process and characterisation of polyaniline (PANI) printed on bond and photographic papers using a desktop inkjet thermal printer. To enable printing, a solution composed by PANI, n-methyl-2-pyrrolidone, ethylene glycol, alcohol and water must be prepared. PANI is printed on bond and photographic paper and then doping of PANI is performed by hydrochloric acid vapour exposure. Micro-Raman spectroscopy showed that PANI printed on paper keeps its basic characteristics. The results from electrical measurements showed that the surface resistivity of the printed PANI samples decreases by increasing the printing number, i.e. the number of layers that were deposited, and depends slightly on the paper type. A stretched semicircle followed by a linear upward tail, attributed to Warburg impedance combined with other intrinsic mechanisms of PANI on porous media, are always present on the Cole-Cole plots obtained for doped-PANI on bond paper. It was shown that these parameters significantly change with the relative humidity, opening the possibility to apply PANI/paper-based devices as humidity sensors.