Lighting the world with molecules

Efficient lighting and display have become important concerns in the energy-starved modern world. This has led to new paradigms in lighting and display technologies. Organic molecules provide a new class of active materials for such technologies. This article gives the basic science behind the design of such molecular materials used in displays and lighting.     

Extended Test Time and postsecondary Students with Learning Disabilities: A Model for Decision Making

The most frequently requested accommodation among students with learning disabilities (LD) in postsecondary settings is extended test time. The frequency with which this accommodation is requested and granted compels disability service providers to become knowledgeable about the factors that influence the need for, and appropriateness of, the accommodation. Moreover, the synthesis of these factors becomes the basis for determining if the accommodation is reasonable under federal law. The purpose of this article is to present a step‐by‐step model to be used as a decision‐making process when considering the accommodation of extended test time for postsecondary students with LD. The model is designed to assist disability service providers in the analysis and synthesis of information collected from (1) the student's diagnostic evaluation, (2) the course or classroom test to be accommodated, and (3) student interviews. A list of diagnostic tests from the four most frequently administered test batteries used with adults is provided, along with a concise explanation of how characteristics of LD impact reading, writing, and math, and relate to the need for extended time. This information can be used to determine if extended test time is a reasonable accommodation and to estimate how much additional time to provide.     

From the Editor

Educational Assessment, Evaluation and Accountability -     

International Early Childhood Resources from Educational Research Abstracts (ERA)

The aim was to examine cross-cultural variation in linguistic responsiveness to young children in 10 English-speaking mother–child dyads and 10 Italian-speaking mother– child dyads. All 20 children were late talkers who possessed delays in expressive vocabulary development but age-appropriate cognitive and receptive language skills. Dyads were filmed in 15 minute free play contexts, which were transcribed and coded for measures of maternal linguistic input (e.g. rate, MLU, labels, expansions) and child language productivity (e.g. utterances, different words used). The results revealed that the Italian mothers used more utterances, spoke more quickly and used a more diverse vocabulary than the Canadian mothers. The Italian children mirrored their mothers and also used more utterances and a more diverse vocabulary than the Canadian children. Mothers in both groups used similar percentages of responsive labels and expansions. However, Italian mothers responded to fewer of their children's vocalisations, using a smaller percentage of imitations and interpretations than the Canadian mothers. Correlations between maternal input and children's language productivity revealed that contingent language measures (e.g. imitations, interpretations, expansions) were related to high levels of productivity in children in both cultural groups. The results support the use of language interventions based on increasing maternal responsiveness for these children at the one-word stage of language development. They also point to differences that may be culturally based. For example, Italian mothers use faster rates of interaction and appear to have higher expectations for their children's verbal participation in interaction. This is reflected in higher rates of language production from their children, even though children in both cultural groups have similar vocabulary sizes.     

Environmentally-induced stone decay: the cumulative effects of crystallization–hydration cycles on a Lincolnshire oopelsparite limestone

An investigation has been undertaken at St Andrew’s church, Walpole St Andrew, Norfolk, to establish the underlying causes of the observed stone decay to the upper parts of the six stone piers. The stone decay was first recorded in the early 1930s. The salt-contaminated masonry within the church has been shown to undergo severe salt decay during the summer, with little damage occurring over the winter months. The south aisle piers have been shown to decay 2.5 times faster than the north aisle piers. Although crystallization–hydration cycles have been identified, the rate of decay is at its greatest when the cycling is relatively infrequent. This was not the expected trend. Furthermore, it has been shown that during extended periods where the ambient relative humidity is less than 75%, the rate of decay reaches a maximum. It is the length of this ‘drying’ period that apparently has the greatest influence on the rate of decay and could explain the significant difference in the rate of decay between the south and north aisle piers. The results have serious implications for passive conservation, where it is often recommended to lower the ambient relative humidity to well below the equilibrium relative humidity of the salt contaminant, to avoid crystallization–hydration cycles. Since, at the time of building, the church was situated on the coast, it is possible that the sodium chloride contamination occurred during the building process (1440–1520), particularly since the area was prone to sea-flooding at this time. Alternatively, the salt could have been applied as a treatment during the general restoration of 1897. Whatever the source of the salt, it seems likely that the ambient environment was changed by the insertion of a sealed floor in 1897, which could account for the onset of the salt decay.