A comparison of the nonlinear response of the ear to air and to bone-conducted sound.

The nonlinear response of the ear to air-conducted sound has been studied to some depth. However, the nonlinear response of the ear to bone-conducted sound has received less attention. A comparison of the nonlinear response of humans to air and bone-conducted sound is presented. Two different human subject test techniques were combined in this investigation. The first was a psychoacoustic investigation measuring the perceived cancellation of a bone-conducted sound stimulus with another air-conducted sound stimulus. The measurement was accomplished through a loudness-matching technique. The second investigation used distortion product otoacoustic emissions (DPOAEs) to make objective measurements of the response of the ear to both air-conducted sound and bone-conducted sound. The results were compared to determine whether the measured compression effects were similar for the different types of stimuli. Results show that both the measured psychoacoustic response and the measured objective response of the ear to air-conducted sound and to bone-conducted sound were similar at 2 and 4kHz.

The effects of contextualization on fluency in three groups of children.

This study investigated the effects of contextualization on fluency in 12 school-age children who stutter (CWS), 11 children with language impairment (CLI), and 12 children with normally developing fluency skills (CNF). Participants in the study were between the ages of 8 and 12 years and were matched for age and sex. Four discourse samples were elicited by asking participants to (a) generate two scripts related to cooking and (b) retell two stories. Having objects or pictures immediately available contextualized a cooking task and a retelling task; another set of cooking and retelling tasks were decontextualized. Moments of disfluency were identified and coded for three primary categories of disfluency: stuttering-type, normal-type, and mazing. For CWS, a significant reduction in frequency of stuttering was noted in the contextualized script generation, and mazing occurred at a significantly higher frequency than did stuttering-type or normal-type disfluencies across the four tasks. For all three groups, both decontextualized conditions produced greater frequencies of normal-type disfluency and mazing. In addition, narrative retelling tasks yielded higher frequencies of disfluency than did the two cooking scripts.

Attaining, sustaining, and focusing attention: intervention for children with ADHD.

An alternative intervention approach for children with ADHD, a "situational-discourse-semantic model," is described. This approach examines the interactions between environmental factors and a student with ADHD and determines the roles of these factors in the establishment of a student's "deficit." Once this is accomplished, selected factors can be manipulated to increase the student's ability to attain the attention needed for academic tasks, to sustain such attention during academic tasks, and then to focus attention on key task elements so that a more effective environment for learning and communication is achieved. The application of the model's principles is illustrated through case study descriptions of therapy interactions with a young boy with ADHD.

The acceleration of gallstone destruction with synchronous biliary lithotripsy and contact dissolution in vitro using three cholesterol-solubilizing solvent.

In the first-known application of its kind, shockwave lithotripsy and contact-solvent dissolution of large, calcified gallstone burdens were performed simultaneously with three chemical solvents, each tested separately in an in vitro model, with the combined effects on gallstone eradication examined. Two solvents, ethyl propionate and isopropyl acetate, were chosen for their solubilizing ability and potentially high level of patient safety. The third solvent, a 70%:30% mixture of methyl tert-butyl ether (MTBE) and dimethyl sulfoxide (DMSO), was chosen for its known ability to accelerate the dissolution of calcium-containing gallstones. All stones were matched for size, weight, and number. Gallstone lithotripsy performed in ethyl propionate was significantly more effective (P less than .02) in the production of fragments less than 2 mm when compared with bile; lithotripsy with isopropyl acetate and the MTBE/DMSO mixture showed no statistically significant effect. Biliary lithotripsy performed in an ethyl propionate medium may enhance gallstone dissolution and the production of small fragments (diameter less than 2 mm).

On the nature of phonological development: evidence from normal children's spelling errors.

Spelling errors of 45 elementary school children were analyzed for phonological process patterns. A considerable proportion of errors involved both syllabic reduction and feature changes similar to those seen in normal speech development. Results are discussed with respect to application of phonological constructs to the study of development of speech production. An alternative psychological model of development is proposed in outline.

Cohesion in the narratives of good and poor readers.

Reading requires the ability to process language in a manner that is decontextualized from any ongoing event. One hundred and fifty high and low achieving kindergarten and first-grade children were evaluated for differences in the use of decontextualized language. Subjects were required to retell a story to a listener. The cohesion present in the stories was evaluated for (a) propositional completeness and relevance (unity) and (b) clarity (coherence). Results indicated that low achievers in reading, irrespective of grade level, exhibit less cohesion in their use of decontextualized language.

The FDA's new procedures for the use of investigational drugs in treatment.

The Food and Drug Administration has established new procedures to make promising investigational drugs available for treatment of patients with immediately life-threatening or serious diseases as early in the drug development process as possible and well before general marketing begins. The purpose of this article is to inform the medical community about these new procedures and to facilitate their implementation. Examples of immediately life-threatening and serious diseases are given and the procedures that physicians should use to obtain a drug under the new regulations are described. The treatment use of zidovudine (Retrovir), while still in the investigational phase, is described as a case study. The article also summarizes the Food and Drug Administration's new procedures under which drug sponsors can charge for investigational drugs.

Formation of negative-index-change waveguide lenses in LiNbO(3) by using ion milling.

We report, for the first time to our knowledge, fabrication of two types of negative-index-change waveguide lens in LiNbO(3) by using ion milling. The first type is an analog Fresnel lens formed by grooves milled into the waveguide. The second is a hybrid lens that combines analog Fresnel zones in the central region with chirp gratings on the sides formed by the same means. We have obtained simultaneously high-efficiency and near-diffraction-limited focusing characteristics in both types of lens. The ion-milling technique employed should be capable of producing similar lenses in any other waveguide substrate, such as GaAs.

Use of situational cues by preschool children.

Pictures often are used in language intervention programs to elicit selected linguistic constructions or to teach concepts to children below the age of 5 years. However,, preschool children frequently are egocentric in their perceptions and in their language, and are unable to view a situation from a perspective other than their own. This study presented children who were in Piaget's preoperational period of development with pictures accompanied by a one-word descriptive phrase and asked the children to explain what was meant by the utterance. It was found that the younger child generally was more egocentric in his interpretations, and his responses reflected less attention to the situational cues present in the picture. The results are discussed in light of common clinical practices of using pictorial stimuli for children with language problems.