Periodic behavior in a random environment.

Studied the tendency of animals to search periodically in temporally random environments by presenting 10 male rats with random-interval (RI) 60- and 120-sec schedules. Power spectra revealed a periodicity of responding of 20–50 sec for all Ss regardless of condition. A 2nd periodicity of 5–20 sec was strongest under the RI 60-sec schedule. Optimality theory suggested that periodic responding is better than random responding in obtaining food sooner on average, but the theory did not account for multiple periodicities. These multiple periodicities also could not be explained by a single-oscillator, information-processing version of the scalar expectancy theory proposed by J. Gibbon and R. M. Church (see record 1992-41865-001) or by the behavioral theory of timing proposed by P. R. Killeen and J. G. Fetterman (see record 1988-28629-001). The periodicities were consistent with a connectionist version of scalar expectancy theory that has nonscalar emergent properties. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Beginning mathematics teachers' ways of knowing: the link with working for emancipatory change

In this article, drawing on extended interview data collected as part of a larger study, a model of the ways of knowing of beginning mathematics teachers is elaborated. Central to the model is the construct 'authority' which links authoritative knowing and the authorship of knowledge. Four epistemological perspectives are described: silence, external authority, internal authority and the authority of self and reason. These are linked to two different traditions in mathematics classrooms - 'school maths' and 'inquiry maths' - and to the commitment of beginning mathematics teachers to working for emancipatory change in education.     

Sex differences, androgyny, and approach responses to erotica: A new variation on the old volunteer problem.

In Study 1, 52 male and 41 female college students were ostensibly given a choice between a hard-core, "lustful" film and a soft-core, "loving" film. Consistent with predictions, results indicate relatively less approach of the lustful theme film by females. Study 2 was a field experiment in which 43 female and 41 male college students were contacted by telephone and asked to volunteer for an experiment involving erotica or one involving perception of geometric figures. Females were less likely than males to volunteer for a study involving erotica, regardless of whether it was described as hard- or soft-core in nature. Results for Ss who had completed the Bem Sex-Role Inventory indicated that the effect was obtained only for sex-typed (vs androgynous) Ss. The possible influence of S self-selection on laboratory studies in this area is considered. (35 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Trace element exposure in the environment from MSW landfill leachate sediments measured by a sequential extraction technique

Dredged leachate sediments from eight MSW landfills were dried and homogenized, and metals sequentially extracted. The concentrations of cadmium (Cd), copper (Cu), chromium (Cr), iron (Fe), lead (Pb), manganese (Mn), nickel (Ni) and zinc (Zn) were found to be similar to those reported for sewage sludge, and generally below the EU limits for use of sludge on agricultural land. Sequential extraction of the samples showed that the largest fractions of the heavy metals were associated with Fe- or Mn-oxides. Cr and Cu were the only metals investigated that were associated with the organic matter in the sediments to any significant extent (2-10% of Cr and 10-28% of Cu). Since the largest fractions of the metals studied were bound to Fe-oxides, and thus had a low mobility, these metals will generally have a low bioavailability under aerobic conditions when present in leachate sediments. This is most likely also valid for particulate matter suspended in MSW landfill leachate and released to the environment, since this is the source of the sediments.     

The interaction between design and occupier behaviour in the safety of new homes

The design of new homes includes many safety features intended to protect occupiers from injury or ill health within the home, however the effectiveness of these primary intervention measures is likely to be affected by user behaviour. This study examined the interaction between user activity and dwelling design and how this might affect health and safety. It aimed to identify how people use features within new homes and how this may limit the protection afforded by building design, codes and regulations. Forty, home-based, semi-structured, in-depth interviews and home inspections were conducted with individuals recently inhabiting a new home. A range of behaviours were reported in relation to building features including fire doors, pipes and cables, and loft access, which may lead to increased risk of injury or ill-health. For example, occupiers described interfering with the self-closing mechanisms on fire doors and drilling into walls without considering the location of services. They also reported knowingly engaging in unsafe behaviour when accessing the loft, increasing their risk of falls. The accounts suggest that designers and builders need to give greater consideration to how occupier behaviour interacts with building features so that improvements in both design and occupier education can lead to improved health and safety.     

Production of biodiesel from waste vegetable oil using impregnated diatomite as heterogeneous catalyst

In this study, biodiesel was produced from waste vegetable oil using a heterogeneous base catalyst synthesized by impregnating potassium hydroxide (KOH) onto diatomite. Response surface methodology based on a central composite design was used to optimize four transesterification variables:temperature (30–120 °C), reaction time (2–6 h), methanol to oil mass ratio (10%–50%) and catalyst to oil mass ratio (2.1%–7.9%). A quadratic poly-nomial equation was obtained to correlate biodiesel yield to the transesterification variables. The diatomite–KOH catalyst was characterized using X-ray diffraction (XRD), Fourier transform infra-red spectroscopy (FTIR) and a scanning electron microscope (SEM) equipped with an energy dispersive X-ray detector (EDS). A maximum biodiesel yield of 90%(by mass) was obtained. The reaction conditions were as follows:methanol to oil mass ratio 30%, catalyst to oil mass ratio 5%, reaction time 4 h, and reaction temperature 75 °C. The XRD, FTIR and SEM (EDS) results confirm that the addition of KOH modifies the structure of diatomite. During impregnation and calcination of the diatomite catalyst the K2O phase forms in the diatomite structural matrix and the active basicity of this compound facilitates the transesterification process. It is possible to recycle the diatomite–KOH catalyst up to three times. The crucial biodiesel properties from waste vegetable oil are within the American Stan-dard Test Method specifications.     

Droplet pinning by PEM fuel cell GDL surfaces

In this work, side view images of liquid–gas–solid interfaces are observed during the evaporation of liquid water droplets on various commercially available untreated gas diffusion layers (GDLs). The change in contact diameter as a function of evaporative volume loss is measured to quantify the unpinning rates of micro-sized droplets. This contact diameter pinning behaviour during evaporation is correlated to the material topography, which is quantified through profilometry measurements. The carbon fibre paper with the smallest average roughness (15 μm) exhibits the strongest degree of pinning (unpinning at a rate of 0.13 mm/μL). Higher average surface roughnesses for felt (30 μm) and cloth yarn (32 μm) result in higher unpinning rates, 0.21 mm/μL and 0.19 mm/μL, respectively. These results indicate that common GDL materials exhibit Cassie–Baxter wetting behaviour, and reduced GDL roughness promotes droplet pinning. The material-specific droplet contact diameter progression should be considered during GDL selection for polymer electrolyte membrane (PEM) fuel cells. This work provides insight into the effect of GDL material properties on gas channel water management, as water droplets are expected to experience similar pinning to that observed in this work within the cathode gas channels of a PEM fuel cell.     

Works In/On//Around///Behind Progress

Artist Hilary Powell describes how her work in film, food and the pop-up book offers playful critiques of regeneration and place making. Copyright © 2012 John Wiley & Sons, Ltd.