Variable-order variable-step algorithms for second-order systems. Part 2: The codes

In a companion paper, Thomas and Gladwell,⁴ the authors designed a class of multistage methods for second-order systems of ordinary differential equations (ODE's), together with local error estimators based on embedding techniques. Here we provide a set of subroutines implementing the algorithms and discuss our numerical experience with the resulting codes.     

Study on the acid hydrolysis of Peat: 1. extraction of carbohydrates

Peat and its derived products such as peat extracts or hydrolysates offer a variety of possibilities as raw materials for the development of chemical and biochemical processes. Acid hydrolysis of peat yields soluble carbohydrates which can be utilised as fermentation media. In this work, Sphagnum peat moss was hydrolysed under various conditions of H₂SO₄ concentration, retention time, temperature, peat concentration, peat particle size distribution and original moisture content in the peat. The results suggest that mild conditions of hydrolysis, which will minimise possible negative effects on other nutrients available in peat, are adequate for the release of the carbohydrates present in peat. It was found that peat particle size distribution and original moisture content as well as peat concentration will also affect the yield of carbohydrates obtained.     

Does Head Start work? A 1-year follow-up comparison of disadvantaged children attending Head Start, no preschool, and other preschool programs.

This article examines how successful Project Head Start has been as a preschool program for economically disadvantaged children. Most Head Start evaluations have not controlled for initial differences between Head Start and comparison groups. They have also limited comparisons to those with no preschool experience, rather than considering other preschools as an alternative comparison group. Subjects were 969 disadvantaged children attending Head Start, other preschool, or no preschool in 1969–1970, longitudinally evaluated on a variety of cognitive measures. Large initial group differences were observed between Head Start children and both comparison groups, with those in Head Start at a disadvantage on nearly every demographic and cognitive measure. Adjusting for initial background and cognitive differences, Head Start children showed significantly larger gains on the Preschool Inventory and Motor Inhibition tests than either comparison group, with Black children in Head Start (especially those of below-average initial ability) gaining the most. However, despite substantial gains, Head Start children were still behind their peers in terms of absolute cognitive levels after a year in the program. Head Start proved an impressive instrument of short-term change, even compared with other preschool experience. Gains in behaviors other than intelligence suggest that the effects may not be limited to the cognitive domain. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Videotape replay in marital therapy.

24 couples seeking outpatient treatment for marital problems were randomly assigned to 1 of 4 treatment conditions and to 1 of 4 therapists. Two of the treatment formats involved the use of videotape feedback as part of the marital therapy procedure. To measure the expected additive effects of videotherapy techniques, comparisons between couples were made of marital adjustment, self-concept, and satisfaction with therapy (e.g., Marital Adjustment Scale, Pre-Counseling Inventory). At the conclusion of therapy, both marital adjustment reports and self-perception scores had significantly increased from the pretreatment data obtained for all groups. There was a significant therapist effect and a significant overall therapist-by-treatment format interaction, but the expected main effect for treatment format was not obtained. The interpretable patterns found in the significant therapist-by-treatment interactions suggest that there is an enhancement effect for at least some forms of psychotherapy in which some clinicians employ video techniques. (32 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The roles of humans and computers in distributed planning for dynamic domains

The requirements and issues associated with computational representations for planning extend beyond those apparent in real-time control, where a substantial, existing research literature informs designers. To assist in the identification of requirements for planning representations, this paper provides two resources: (1) a theoretical foundation drawn from computer science and (2) illustrations of representations and corresponding work practice for real-time control and planning for the US Shuttle program. Together, these resources illustrate the human role in the planning process, and the need for work practices and information that combine to assist human operators in interpreting a representation that is loosely coupled to the physical world while shared among and modified by multiple participants in the planning process.

Suicide attempters within a delinquent population.

Contrasted 30 13–15 yr old delinquents who had attempted suicide with 120 delinquent controls. Multiple regression analyses showed that suicidal ideation, depression, gender, a tendency to act out, conflict with parents, childhood hyperactivity, and the interactions of gender with depression and with acting out accounted for 49% of the variance in suicide attempts. Females were found to attempt suicide 2? times as often as males. Females were also more likely to attempt suicide when depressed than were similarly depressed males. Male and female delinquents who engaged in a high level of acting out were equally likely to attempt suicide, but females who did not act out were more likely to attempt suicide than males who did not act out. Similarities between these adolescent attempters and adult suicide attempters described in the literature are discussed. (34 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)