Spectroscopic and biochemical analysis of regions of the cell wall of the unicellular 'mannan weed', Acetabularia acetabulum.

Although the Dasycladalean alga Acetabularia acetabulum has long been known to contain mannan-rich walls, it is not known to what extent wall composition varies as a function of the elaborate cellular differentiation of this cell, nor has it been determined what other polysaccharides accompany the mannans. Cell walls were prepared from rhizoids, stalks, hairs, hair scars, apical septa, gametophores and gametangia, subjected to nuclear magnetic resonance and Fourier transform infrared spectroscopy, and analyzed for monosaccharide composition and linkage, although material limitations prevented some cell regions from being analyzed by some of the methods. In diplophase, walls contain a para-crystalline mannan, with other polysaccharides accounting for 10-20% of the wall mass; in haplophase, gametangia have a cellulosic wall, with mannans and other polymers representing about a quarter of the mass. In the walls of the diplophase, the mannan appears less crystalline than typical of cellulose. The walls of both diploid and haploid phases contain little if any xyloglucan or pectic polysaccharides, but appear to contain small amounts of a homorhamnan, galactomannans and glucogalactomannans, and branched xylans. These ancillary polysaccharides are approximately as abundant in the cellulose-rich gametangia as in the mannan-rich diplophase. In the diplophase, different regions of the cell differ modestly but reproducibly in the composition of the cell wall. These results suggest unique cell wall architecture for the mannan-rich cell walls of the Dasycladales.

Effects of behavior-contingent and fixed-time release contingencies on frequency and duration of therapeutic restraint.

Reducing therapeutic restraint is a desirable outcome for programs that serve individuals who exhibit challenging behaviors. This study investigated the effects of modifying the criterion for release from therapeutic restraint on frequency and duration. Release from restraint was changed from a behavior-contingent criterion (restraint terminated when a specified duration of calm behavior was demonstrated) to a fixed-time criterion (restraint terminated when a predetermined duration elapsed independent of behavior) with one child and two adolescents with acquired brain injury and difficult-to-manage behaviors. For all three students, the duration of time they were exposed to therapeutic restraint decreased with the fixed-time release criterion, whereas the frequency of restraint did not change. Practical implications of these results and future research opportunities are discussed.

Effects of immediate performance feedback on implementation of behavior support plans.

Research has focused on increasing the treatment integrity of school-based interventions by utilizing performance feedback. The purpose of this study was to extend this literature by increasing special education teachers' treatment integrity for implementing antecedent and consequence procedures in an ongoing behavior support plan. A multiple baseline across teacher-student dyads (for two classrooms) design was used to evaluate the effects of performance feedback on the percentage of antecedent and consequence components implemented correctly during 1-hr observation sessions. Performance feedback was provided every other week for 8 to 22 weeks after a stable or decreasing trend in the percentage of antecedent or consequence components implemented correctly. Results suggested that performance feedback increased the treatment integrity of antecedent components for 4 of 5 teachers and consequence components for all 5 teachers. These results were maintained following feedback for all teachers across antecedent and consequence components. Teachers rated performance feedback favorably with respect to the purpose, procedures, and outcome, as indicated by a social validity rating measure.

Antecedent analysis of therapeutic restraint in children and adolescents with acquired brain injury: a descriptive study of four cases.

Therapeutic restraint is sometimes required as a component of clinical intervention for persons who have serious behaviour disorders. However, there are few studies that describe empirically the conditions under which restraint is utilized. This project was a retrospective analysis of incident reports on the application of therapeutic restraint with four students (ages 10-16 years) who had acquired brain injury and attended a community-based programme of education and neurorehabilitation. Specifically, situations and interactions were examined that were in effect immediately prior to the implementation of restraint. This antecedent analysis identified several common influences, as well as effects that were unique to individual students. The role of antecedent events as "precipitants" to restraint and respective treatment implications are discussed.