Effect of Particle Size on Risk Assessment of Direct Soil Ingestion and Metals Adhered to Children's Hands at Playgrounds

The quantity of heavy metals in soil is measured after 2‐mm sieving in Japan for risk assessment of direct soil ingestion. A study was conducted on the relationship between the size of soil particles and quantity of heavy metals in soil, and the particle‐size distribution of soil adhered to children's hands, and the risks of direct intake of soil considering the particle sizes ingested were evaluated. The results showed that smaller particles had a tendency to contain more heavy metals than bigger ones, that the particle size of approximately 90% of the soil particles from playgrounds adhered to children's hands was less than 100 μm, and that 2‐mm sieving in preparation for measuring heavy metal content caused underestimation of the risk of direct soil intake. The amount of heavy metals on children's hands after playing outside was investigated. Various metals and soil were adhered to their hands, and the amount of soil adhered could be estimated from the concentration of metals. To develop accurate risk assessment, the particle‐size distribution of ingested soil and more detailed scenarios of soil intake are necessary.     

Characterization of certain incomplete block designs

It is shown that certain inequalities known for partially balanced incomplete block (PBIB) designs remain valid for general incomplete block designs. Some conditions for attaining their bounds are also given. Furthermore, the various types of PBIB designs are characterized by relating blocks of designs with association schemes. The approach here is based on the spectral expansion of NN' for the incidence matrix N of an incomplete block design.     

Some bounds on balanced block designs

Bounds on the latest root of the C-matrix and the number of blocks for a variance-balanced block design are given. These results contain the well-known results as special cases.     

A meta-analysis of infants’ word-form recognition

Recognizing word forms is an important step on infants’ way toward mastering their native language. The present study takes a meta-analytic approach to assess overarching questions on the literature of early word-form recognition. Specifically, we investigated the extent to which there is cross-linguistic evidence for an early recognition lexicon, and how it may be influenced by infant age, language background, and familiarity of the selected stimuli (approximated by parent-reported word knowledge). Our meta-analysis—with open data access on metalab.stanford.edu—was based on 32 experiments in 16 different published or unpublished studies on infants 5–15 months of age. We found an overall significant effect of word-form familiarity on infants’ responses. This effect increased with age and was higher for infants learning Romance languages than other languages. We further found that younger, but not older, infants showed higher effect sizes for more familiar word lists. These insights should help researchers plan future studies on word-form recognition.     

Ordinary Usage of New Media: Internet Usage via Mobile Phone in Japan

Abstract:  This paper, by analyzing Internet usage via mobile phones in Japan, aims to clarify an aspect of information behavior in present-day Japanese society.
Many discourses on the mobile Internet in Japan, either positive or negative, emphasize its novelty and describe this new media as an exotic phenomenon. These discourses can be divided into two categories. The nationalistic discourses and the moral panic discourses. Both types of discourse have built certain images of social influences of the mobile Internet in the future. However, it would be unwise to conclude that those images of the mobile Internet express the reality of this new medium, simply because they lack empirical ground.
With these points in mind, based on the result of our national survey conducted in 2001, we would like to show the actual status of use of the mobile Internet and discuss that the ordinary usage is a critically important realm to understand the process of social reception of the mobile Internet. As our data shows, although the actual usage of the mobile Internet is not very conspicuous, it gives us a chance to understand how the mobile Internet has been integrated into our everyday lives.     

Infants' preference for speech is stable across the first year of life: Meta-analytic evidence

Previous work suggested that humans' sophisticated speech perception abilities stem from an early capacity to pay attention to speech in the auditory environment. What are the roots of this early preference? We assess the extent to which it is due to it being a vocal sound, a natural sound, and a familiar sound through a meta-analytic approach, classifying experiments as a function of whether they used native or foreign speech and whether the competitor, against which preference is tested, was vocal or non-vocal, natural or artificial. We also tested for the effect of age. Synthesizing data from 791 infants across 39 experiments, we found a medium effect size, confirming at the scale of the literature that infants reliably prefer speech over other sounds. This preference was not significantly moderated by the language used, vocal quality, or naturalness of the competitor, nor by infant age. The current body of evidence appears most compatible with the hypothesis that speech is preferred consistently as such and not just due to its vocal, natural, or familiar nature. We discuss limitations of the extant body of work on speech preference, including evidence consistent with a publication bias and low representation of certain stimuli types and ages.     

General upper bound for the number of blocks having a given number of treatments common with a given block

The purpose of this paper is systematically to derive the general upper bound for the number of blocks having a given number of treatments common with a given block of certain incomplete block designs. The approach adopted here is based on the spectral decomposition of N′N for the incidence matrix N of a design, where N' is the transpose of the matrix N. This approach will lead us to upper bounds for incomplete block designs, in particular for a large number of partially balanced incomplete block (PBIB) designs, which are not covered with the standard approach (Shah 1964, 1966), Kapadia (1966)) of using well known relations between blocks of the designs and their association schemes. Several results concerning block structure of block designs are also derived from the main theorem. Finally, further generalizations of the main theorem are discussed with some illustrations.     

A system for decision support without explicit objective functions

This paper presents a conversational decision support system: Resource Allocation in Business Operation under Uncertain Worth (RAINBOW). The focus is placed on the loosely structured decision situation where the multiple objective functions are given only implicitly and should be locally approximated by the decision maker as the decision making process proceeds. Basically, RAINBOW supports the process of convergence to a preferred alternative by giving the decision maker information which will help him form consistent evaluations of the utility function, the objective functions and the solution for the decision problem.     

Recommended Reference Values for Risk Assessment of Oral Exposure to Copper

The U.S. Environmental Protection Agency's (EPA) Integrated Risk Information System (IRIS) database, the authoritative source of U.S. risk assessment toxicity factors, currently lacks an oral reference dose (RfD) for copper. In the absence of such a value, various health-based reference values for copper are available for use in risk assessment. We summarize the scientific bases and differences in assumptions among key reference values for ingested copper to guide selection of appropriate values for risk assessment. A comprehensive review of the scientific literature best supports the oral RfD of 0.04 mg/kg body weight/day derived by EPA from their Drinking Water Action Level. This value is based on acute gastrointestinal effects but is further supported by broader analysis of copper deficiency and toxicity.