Reading in the dark: effects of age and contrast on reading speed and comprehension

OBJECTIVE: To explore the effects of contrast reduction on younger and older adults' reading behavior and to examine whether readers rely on word predictability to compensate for poor contrast. BACKGROUND: Poor contrast can degrade text and may influence reading behavior. Readers may compensate for visual degradation of text by taking advantage of word predictability. METHOD: In Experiment 1, 5 younger and 5 older adults read sentences presented with 10 levels of contrast. In Experiment 2, 40 younger and 40 older adults read high-, medium-, and low-contrast sentences that varied in target word predictability (high vs. low). RESULTS: Relative to those of younger adults, older adults' reading rates were more slowed by low contrast; comprehension was less influenced by contrast (i.e., not significantly). Older adults read high-predictability words faster and comprehended them better than low-predictability words, significantly so for high- and medium-contrast sentences. Younger adults comprehended high-predictability words significantly better than low-predictability words for high- and low-contrast sentences. CONCLUSION: Low contrast was more detrimental for older adults. High-predictability words benefited older adults by significantly reducing their reading times and benefited all readers by significantly increasing their comprehension. APPLICATION: The current findings demonstrate the benefit of adequate contrast and word predictability for optimal text design to facilitate both reading times and reading comprehension.     

Acceleration and filtering in the generalized Landweber iteration using a variable shaping matrix

The generalized Landweber iteration with a variable shaping matrix is used to solve the large linear system of equations arising in the image reconstruction problem of emission tomography. The method is based on the property that once a spatial frequency image component is almost recovered within in in the generalized Landweber iteration, this component will still stay within in during subsequent iterations with a different shaping matrix, as long as this shaping matrix satisfies the convergence criterion for the component. Two different shaping matrices are used: the first recovers low-frequency image components; and the second may be used either to accelerate the reconstruction of high-frequency image components, or to attenuate these components to filter the image. The variable shaping matrix gives results similar to truncated inverse filtering, but requires much less computation and memory, since it does not rely on the singular value decomposition.     

Is the breast best for children with a family history of atopy? The relation between way of feeding and early childhood morbidity

BACKGROUND: Previous studies reported that breast-feeding protects children against a variety of diseases, but these studies were generally conducted on "high-risk" or hospitalized children. This paper describes the results of our study on the effects of breast-feeding on rate of illness in normal children with a family history of atopy. METHODS: A historic cohort approach of 794 children with a family history of atopy was used to assess the effects of breast-feeding on illness rates. Family history of atopy was based on allergic diseases in family members as registered by the family physician. Illness data from birth onwards were available from the Continuous Morbidity Registration of the Department of Family Medicine. Information on breast-feeding was collected by postal questionnaire. We then compared rates of illness between children with a family history of atopy who were and who were not breast-fed. RESULTS: Breast-feeding was related to lower levels of childhood illness both in the first and the first three years of life. In the first year of life they had fewer episodes of gastroenteritis, lower respiratory tract infections, and digestive tract disorders. Over the next three years of life they had fewer respiratory tract infections and skin infections. CONCLUSIONS: Our results suggest a protective effect of breast-feeding among children with a family history of atopy that is not confined to the period of breast-feeding but continues during the first three years of life. Breast-feeding should be promoted in children with a family history of atopy.     

A new approach to defining a multidisciplinary field of science: The case of cardiovascular biology

This paper describes a new and objective method for tackling the problem of defining a multidisciplinary research area for bibliometric analysis. The test field was cardiovascular biology. A three stage process was adopted in setting a boundary around this research field:

1. Appropriate sections of a hierarchical subject classification scheme, Medical Subject Headings (MeSH), were developed into a “MeSH filter” through which papers indexed in MEDLINE were screened.
2. A panel of cardiovascular experts reviewed the core set of classification terms, identifying irrelevant and missing areas, facilitating the development of a more sophisticated “filter”.
3. The definition was validated using publication lists from research departments with a known interest in cardiovascular research.

This iterative process resulted in a definition of the field which captured basic and clinical research papers from the international biomedical research community and which was recognisable to experts in the field of cardiovascular research. Importantly, the field boundary also excluded publications which were not relevant to cardiovascular research. The process of involving experts in shaping the field definition also yielded two intangible, but key benefits: (a) it lent credibility to subsequent analyses, the results of which were to be presented to policy-makers in cardiovascular biology, and (b) it served to shape consensus among the cardiovascular experts on the full range of scientific disciplines that are relevant to their field. Analysis of international publishing in cardiovascular research revealed that whilst the UK and US dominate in total numbers of papers, the relative emphasis on cardiovascular research in these countries (as a proportion ofall biomedical publishing) is actually quite low, and declining. Japan and Germany in contrast appear to give greater emphasis to cardiovascular research in their national portfolios of biomedical science, and between 1988–1991 Japan established a marked increase in activity.     

A real-time video tracking system

Object identification and tracking applications of pattern recognition at video rates is a problem of wide interest, with previous attempts limited to very simple threshold or correlation (restricted window) methods. New high-speed algorithms together with fast digital hardware have produced a system for missile and aircraft identification and tracking that possesses a degree of ``intelligence' not previously implemented in a real-time tracking system. Adaptive statistical clustering and projection-based classification algorithms are applied in real time to identify and track objects that change in appearance through complex and nonstationary background/foreground situations. Fast estimation and prediction algorithms combine linear and quadratic estimators to provide speed and sensitivity. Weights are determined to provide a measure of confidence in the data and resulting decisions. Strategies based on maximizing the probability of maintaining track are developed. This paper emphasizes the theoretical aspects of the system and discusses the techniques used to achieve real-time implementation.     

The smooth (tractor) operator: insights of knowledge engineering

The design of and training for complex systems requires in-depth understanding of task demands imposed on users. In this project, we used the knowledge engineering approach (Bowles et al., 2004) to assess the task of mowing in a citrus grove. Knowledge engineering is divided into four phases: (1) Establish goals. We defined specific goals based on the stakeholders involved. The main goal was to identify operator demands to support improvement of the system. (2) Create a working model of the system. We reviewed product literature, analyzed the system, and conducted expert interviews. (3) Extract knowledge. We interviewed tractor operators to understand their knowledge base. (4) Structure knowledge. We analyzed and organized operator knowledge to inform project goals. We categorized the information and developed diagrams to display the knowledge effectively. This project illustrates the benefits of knowledge engineering as a qualitative research method to inform technology design and training.     

Recursive identification of Hammerstein systems with application to electrically stimulated muscle

Modeling of electrically stimulated muscle is considered in this paper where a Hammerstein structure is selected to represent the isometric response. Motivated by the slowly time-varying properties of the muscle system, recursive identification of Hammerstein structures is investigated. A recursive algorithm is then developed to address limitations in the approaches currently available. The linear and nonlinear parameters are separated and estimated recursively in a parallel manner, with each updating algorithm using the most up-to-date estimation produced by the other algorithm at each time instant. Hence the procedure is termed the alternately recursive least square (ARLS) algorithm. When compared with the leading approach in this application area, ARLS exhibits superior performance in both numerical simulations and experimental tests with electrically stimulated muscle.     

Reviewing the contract

The process of preparing and reviewing a contract for a pharmacy computer system is described. The purpose of the contract is to establish rules governing the relationship between the vendor and the buyer. It should identify clearly the performance expectations of both parties. The contract negotiating process also allows each party to gain insight to the other's motives by way of responses to proposals for specific contract inclusions. Generally, the buyer should be wary of: (1) a vendor who insists that his form contract be signed without modification; (2) signing more than one contract with the same vendor; (3) vague, nonquantifiable performance criteria; (4) "best-efforts" warrantees; (5) an expectation that difficulties with the vendor can be solved if the remedy is not in the contract; and (6) acceptance upon delivery. The buyer should strive for: (1) a complete contract reflecting the nature of the business deal negotiated, (2) specific performance criteria, (3) warrantees of performance with meaningful remedies, and (4) payments tied to performance. The most important provision of the contract is the one that makes payment to the vendor contingent upon the actual demonstration of results.