Phonological complexity in intervention for Spanish-speaking children with speech sound disorder.

The efficiency of intervention for children with speech sound disorder may be influenced by linguistic complexity of the phonological intervention target. Complex targets, particularly, later-acquired, less-known consonants and consonant clusters, have been linked to greater post-intervention generalization to untargeted phonological structures. Yet there is little direct evidence to support target selection based on linguistic complexity for Spanish-speaking children with speech sound disorder. This intervention study utilizes an experimental single-case design to examine the efficacy of intervention in Spanish using different complex targets (i.e. /ɡɾ/, /bɾ/, and /l/). For each of the four Spanish-speaking children with speech sound disorder, sounds at 0% accuracy during baseline were monitored across the baseline period, during and post-intervention, and at one- and two-month follow-up visits. Over the course of intervention, only one participant achieved mastery of the targeted structure in practiced words. However, all participants demonstrated some amount of broad phonological generalization to untargeted consonants or clusters. Variable learning trajectories and broad phonological generalization are discussed as they relate to participant characteristics and linguistic complexity.

The structure of /s/-sequences: evidence from a disordered system.

This study considers the much-debated markedness and structural status of word-initial /s/-sequences in English by examining the development of KR (male, age 3;6) who has a phonological disorder. Three points in time are discussed: (1) when all initial consonant sequences are reduced to singletons; (2) when only initial /s/-sequences surface correctly; and (3) when all initial consonant sequences surface correctly. While these production patterns are common across developing systems, few accounts have addressed them in terms of structure or markedness. Toward that end, it is argued that KR's /s/-sequences surface as adjuncts, rather than complex onsets. This is explained within optimality theory, whereby high-ranking markedness constraints prevent complex onsets but not adjuncts. The account offers an explanation for consonant sequence asymmetries within and across grammars, allowing for differing representations for /s/-sequences across speakers and for variation exhibited in children's productions. A typology of possible grammars is therefore offered, and clinical implications are considered.

Optimality theory in phonological acquisition.

This tutorial presents an introduction to the contemporary linguistic framework known as optimality theory (OT). The basic assumptions of this constraint-based theory as a general model of grammar are first outlined, with formal notation being defined and illustrated. Concepts unique to the theory, including "emergence of the unmarked," are also described. OT is then examined more specifically within the context of phonological acquisition. The theory is applied in descriptions of children's common error patterns, observed inter- and intrachild variation, and productive change over time. The particular error patterns of fronting, stopping, final-consonant deletion, and cluster simplification are considered from an OT perspective. The discussion concludes with potential clinical applications and extensions of the theory to the diagnosis and treatment of children with functional phonological disorders.

On the characterization of a chain shift in normal and delayed phonological acquisition.

Several theoretical and descriptive challenges are presented by children's phonological substitution errors which interact to yield the effect of a chain shift. Drawing on an archival study of the sound systems of five children (ages 3;5 to 4;0) with normal development and 47 children (ages 3;4 to 6;8) with phonological delay, one such chain shift, namely the replacement of target /theta/ by [f] and the replacement of /s/ by [theta], was identified in the speech of six children from the two subgroups. Different derivational and constraint-based accounts of the chain shift were formulated and evaluated against the facts of change and the children's presumed perceptual abilities. An adequate account in either framework was found to require the postulation of underspecified and, in some instances, nonadult-like underlying representations. Such representations were able to reconcile within a single-lexicon model the presumed production/perception dilemma commonly associated with acquisition. Continuity was also preserved by limiting underlying change to just those lexical items which exhibited a change phonetically.

Client and worker satisfaction in a child protection agency.

Client and staff satisfaction with the workings of a multidisciplinary child protection agency were investigated using interviews and standard questionnaires. The goal was to discover the nature and strength of the helping relationship between service-recipients and providers. Current clients (N = 24) expressed a great deal of satisfaction with the staff and services. The agency staff (N = 21, with 11 employed at least half-time to work directly with families) were relatively satisfied with their jobs, and showed little evidence of the burnout which has been recognized as a risk for child protection workers. They were able to relate empathically to clients and felt enthusiasm for the work. Taking account of possible bias in both sets of answers, there is still evidence that the agency is succeeding in creating a necessary precondition for therapeutic change: the development of accepting and positive worker-client relationships.

Oral delivery and clearance of antiplaque agents from Triclosan-containing dentifrices.

Oral delivery and clearance of Triclosan and zinc were studied following use of three commercially available Triclosan-containing toothpastes. One paste contained 0.3 per cent Triclosan and 2 per cent PVM-MA copolymer, one contained 0.3 per cent Triclosan and 5 per cent sodium pyrophosphate and the third contained 0.3 per cent Triclosan and 0.75 per cent zinc citrate trihydrate. Each gave similar total oral retention of Triclosan (37 per cent-46 per cent of the dose). However, clinically important product differences were observed in the salivary clearance of Triclosan and in Triclosan delivery to plaque. The Triclosan/zinc paste delivered more Triclosan to oral reservoirs (as measured by the area under the salivary clearance curve) than either the Triclosan/PVM-MA or the Triclosan/pyrophosphate paste (p < 0.001). The Triclosan/zinc paste produced higher Triclosan levels in plaque than the Triclosan/PVM-MA paste (109 micrograms/g versus 78 micrograms/g, p < 0.05). Zinc was effectively delivered to oral surfaces by the Triclosan/zinc paste, and was cleared more slowly than Triclosan (single-reservoir t1/2 = 50 min). After use of the Triclosan/zinc paste the zinc level in plaque was 153 micrograms/g, a seven-fold increase over the control. These results demonstrate that good delivery of Triclosan requires a highly optimised formulation. Furthermore, they suggest that the superior clinical effects of the Triclosan/zinc paste are due to a combination of superior delivery of Triclosan to oral sites of action together with effective delivery of a second, complementary antiplaque agent, zinc.

Modification of survival of gamma irradiated mice by adenosine nucleotides.

The administratio prior to irradiation of adenosine triphosphate (ATP) or other adenosine nucleotides, singly or in combination, increased the radioresistance of mice. Post-irradiation treatment with the adenosine nucleotides had no effect on the survival of the irradiated mice. Dose reduction factors of 2.32 could be obtained by pretreatment of mice with the following combination of protective agents: S-2(4-aminobutylamino)ethyl phosphorothioic acid(WR 2822), cysteamine (MEA) and ATP. Since cyclic AMP levels were unchangd in the spleen or gut by administration of cysteamine and other protectors it is unlikely that the increase in preotection was due to changes in cyclic AMP levles. The calcium salt of ATP provided a higher level of protection than the ATP alone, indicating that the protective mechanism of ATP is probably not related to anoxia.