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Biomedical subjects

R L Carpenter

Publications and source records attributed to R L Carpenter.

At least 91 records · Page 5Linked to original sources
PubMed1982

The ontogenesis of agent: cognitive notion.

Children's early 1- and 2-word utterances appear to encode the concept of agent, thus suggesting that this semantic notion has its origin in prior sensorimotor development. Specifically, the nonverbal concept of agent has been alluded to in research regarding young children's development of the cognitive notion of causality and the pragmatic category of requests for action. In this study children's awareness of the nonverbal agent concept was defined by gestural behaviors--that is, actions on objects and other people--occurring during request interactions with their mothers and the investigator. Three children were observed in their homes approximately once a month for 1 year, from their 11th through 22nd months of life. During each hour-long visit, the children were engaged in free play and in tasks designed to result in the children's requesting help from an adult. Based on the observation of the children's changing nonverbal behaviors over the 12 months, a 5-level developmental sequence documenting the evolution of the cognitive notion of agent is presented.

Age Factors↗
PubMed1982

The ontogenesis of agent: linguistic expression.

Three children were followed longitudinally for 12 months, between their 11th and 22nd months of life, to document their development of the linguistic expression of the agent concept. The children were observed approximately once a month in play and structured activities designed to elicit nonverbal and linguistic behaviors indicative of the children's awareness of the agent concept. This study describes how the linguistic behaviors (i.e., vocalizations, single-word utterances, and multiword utterances) were paired with emerging nonverbal agentive behaviors over the 12-month period. The children's first vocalizations were consistently paired with directive nonverbal agentive behaviors. With the emergence of the mature cognitive notion of agent, the children produced single-word utterances coding the agent in agent-action-recipient events. And finally, for two of the children, multiword utterances coding two aspects of agent-action-recipient events were produced. The evolution of paired nonverbal agentive behaviors and different utterance types has provided evidence supporting the linguistic expression of an underlying cognitive notion.

Age Factors↗
PubMed1980

The effects of children's language comprehension level on adults child-directed talk.

The present study attempted to test quasi-experimentally the hypothesis that children's language comprehension level is the major determinant of the modifications characteristic of child-directed talk (CDT). Language comprehension level was varied by selecting four-year-old, language-impaired children with two levels of comprehension. Data on 21 measures of structural and pragmatic aspects of CDT were obtained from videotapes of 20 half-hour, freeplay sessions in which each of ten adults talked individually with one child from each level. A t test for paired samples generated four significant differences (p less than 0.05). Language addressed to the high comprehending children contained (1) more frequent use of the semantic category state, (2) greater lexical diversity, (3) more frequent reference to nonpresent objects, persons, and events, and (4) less frequent nonverbal cueing. Variation in the children's comprehension strategies appears to provide a better explanation for these differences than variation in their comprehension of language structure. An alternate explanation of the results, the conversational model, proved of limited value in explaining structural CDT modifications.

Adult↗
PubMed1980

Relationship between fluid bed aerosol generator operation and the aerosol produced.

The relationships between bed operation in a fluid bed aerosol generator and aerosol output were studied. A two-inch diameter fluid bed aerosol generator (FBG) was constructed using stainless steel powder as a fluidizing medium. Fly ash from coal combustion was aerosolized and the influence of FBG operating parameters on aerosol mass median aerodynamic diameter (MMAD), geometric standard deviation (sigma g) and concentration was examined. In an effort to extend observations on large fluid beds to small beds using fine bed particles, minimum fluidizing velocities and elutriation constant were computed. Although FBG minimum fluidizing velocity agreed well with calculations, FBG elutriation constant did not. The results of this study show that the properties of aerosols produced by a FBG depend on fluid bed height and air flow through the bed after the minimum fluidizing velocity is exceeded.

Aerosols↗
PubMed1979

Toxicity of 0.4- and 0.8-microm sulfuric acid aerosols in the guinea pig.

To determine mortality caused by inhaled sulfuric acid mist, groups of Hartley guinea pigs 2-3 mo old were exposed for 8 h to graded concentrations of aerosols of 0.4 or 0.8 microm mass median aerodynamic diameter. Relative humidity during exposures was maintained at 70-80%. Based on probit analysis, the concentration required to produce 50% mortality (LC50) for deaths to 21 d after exposure was 30 mg/m3 for the 0.8-microm aerosol. For the 0.4-microm aerosol, the LC50 was above 109 mg/m3, the highest concentration obtainable at that particle size. At both particle sizes, the animals either tended to develop severe dyspnea and die minutes (0.4 microm) or hours (0.8 microm) thereafter or appeared nearly unaffected. Lesions in animals that died as a results of 0.4-microm exposures were restricted to hyperinflation; animals that died as a result of 0.8-microm exposures also showed hemorrhage and transudation. No gross or histopathologic changes were observed in animals that appeared unaffected during exposure. Differences in total and/or regional respiratory tract deposition may account for the different responses to the two aerosols.

Aerosols↗
PubMed1978

Elicitor effects on the language obtained from young language-impaired children.

Language samples are typically obtained during speech and language evaluations by the speech-language pathologist to assess the level of expressive language development of young children. These samples are assumed to be accurate representations of the children's language skills. This study examines the effects of the elicitor on the language obtained from three- to six-year-old language-impaired children in a clinical setting. A corpus of nonimitated utterances was collected in 25 min from each of the nine subjects under two conditions: mother as elicitor and clinician as elicitor. The corpus of language collected under each condition was examined using the following measures: (1) numeric-number of utterances; (2) lexical-vocabulary type-token ratio: (3) grammatic-mean length of utterance, (4) percentage of one-morpheme utterances, (5) percentage of two-morpheme utterances, (6) percentage of three- or more morpheme utterances, (7) proportion of grammatical morphemes per utterance (8) semantic-percentage occurrence of semantic categories, and (9) type-token ratio for each of the 13 semantic categories. The data analysis revealed that the elicitor affected the number of utterances collected in a specific time period, but neither the lexical, grammatic, nor semantic aspects of the utterances were affected. The results state practical implications for evaluation procedures used in a clinical setting.

Child Language↗
PubMed1976

Development of acoustic cue discrimination in children.

Three groups of twelve subjects each, ages four, five and six years, respectively, made same-different judgments on six speech discrimination tests. On each test, a single acoustic cue signaled a phonemic difference in minimal pairs which were otherwise acoustically identical. On three of the tests, the independent variable was a spectral cue and on three others a temporal cue was manipulated. With one exception, all subjects passed tests involving a spectral cue, however, significant developmental differences were apparent on tests in which a temporal cue signaled a phonemic difference. The probable contribution of these cues to the perception of speech in young children is discussed.

Auditory Perception↗
PubMed1976

Semantic relations used by normal and language-impaired children at stage I.

Two-word utterances of four language-impaired children at Brown's Stage I level of linguistic development were compared with two-word utterances of four young normal children at the same linguistic level to determine any differences between the two groups in the use of a set of 10 basic semantic relations. Type-token ratios for each semantic relation were used to compare use of semantic relations between groups. A significant difference was obtained for only one relation, with the language-impaired group demonstrating greater diversity in the use of the introducer + entity relation than the normal group. The findings indicated that at Stage I level of linguistic development, the language-impaired children demonstrated a linguistic system no different than the system of normal Stage I children. The findings are discussed relative to possible cognitive and linguistic strategies involved in language acquisition. It is suggested that some language-impaired children rather than being deficient in their ability to understand and code the basic semantic relations demonstrate a deficit in the higher, more complex aspects of the linguistic coding system.

Child, Preschool↗
PubMed1975

Sequelae of central-nervous-system enterovirus infections.

The long-term effects of central-nervous-system enterovirus infections were examined in a controlled follow-up study of 19 children 2 1/2 to eight years of age who had been hospitalized with documented enterovirus infection 17 to 67 months before evaluation. Assessment included medical history, physical and neurologic examination, psychologic testing, and speech and hearing evaluation. Three children (16 per cent) had definite neurologic impairment, five (26 per cent) had possible impairment, and 11 (58 per cent) were free of detectable abnormalities. Children whose illness occurred during the first year of life, when compared to controls, were found to have significantly smaller mean head circumference (50.6 vs. 51.6 cm, P less than 0.033), significantly lower mean I.Q. (97 vs 115, P less than 0.007), and depressed languange and speech skills. Children whose illness occurred after the first year of life were not different from their controls. Children whith central-nervous-system enterovirus infection may have neurologic impairment when infection occurs in the first year of life.

Age Factors↗