bluuebunny/crossref_metadata_2025 huggingface dataset:
Mean Length of Utterance in Children With Specific Language Impairment and in Younger Control Children Shows Concurrent Validity and Stable and Parallel Growth Trajectories
Authors: Rice Mabel L. , Redmond Sean M. , Hoffman Lesa
Published: May 2007

Purpose

Although mean length of utterance (MLU) is a useful benchmark in studies of children with specific language impairment (SLI), some empirical and interpretive issues are unresolved. The authors report on 2 studies examining, respectively, the concurrent validity and temporal stability of MLU equivalency between children with SLI and typically developing children.

Method

Study 1 used 124 archival conversational samples consisting of 39 children with SLI (age 5;0 [years;months]), 40 MLU-equivalent typically developing children (age 3;0), and 45 age-equivalent controls. Concurrent validity of MLU matches was examined by considering the correspondence between MLU and developmental sentence scoring (DSS), index of productive syntax (IPSyn), and MLU in words. Study 2 used 205 archival conversational samples, representing 5 years of longitudinal data collected on 20 children with SLI (from age 5;0) and 18 MLU matches (from age 3;0). Evaluation of growth dimensions within and across groups was carried out via growth-curve modeling.

Results

In Study 1, high levels of correlation among the MLU, DSS, and IPSyn measures were observed. Differences between groups were not significant. In Study 2, temporal stability of MLU matches was robust over a 5 year period.

Conclusions

MLU appears to be a reliable and valid index of general language development and an appropriate grouping variable from age 3 to 10. The developmental stability of MLU matches is indicative of shared underlying growth mechanisms.
Auditory Sensitivity and the Prelinguistic Vocalizations of Early-Amplified Infants
Authors: Hapsburg Deborah von , Davis Barbara L.
Published: May 2007

Purpose

Vocalization development has not been studied thoroughly in infants with early-identified hearing loss who receive hearing aids in the 1st year of life. This study sought to evaluate the relationship between auditory sensitivity and prelinguistic vocalization patterns in infants during the babbling stage.

Method

Spontaneous vocalizations of 15 early-identified infants with varying degrees of hearing sensitivity, from normal to profound hearing loss, were audiotaped and perceptually transcribed. Associations between the infant’s unaided pure-tone average and the following vocalizations were explored: canonical babbling ratio, percentage of utterances containing canonical syllables, canonical syllable shapes, number of syllable sequences, and consonant-onset patterns in canonical syllables.

Results

Hearing sensitivity was significantly associated with the percentage of utterances containing canonical syllables, the vocalization types used in utterances, and canonical syllable shapes used by the infants.

Conclusions

Auditory sensitivity contributes significantly to the emergence of babbling patterns. In addition, there is a need for continued study of the vocalizations of infants with milder forms of hearing loss, because in this study, their vocalizations were highly variable despite having received early amplification.
Correction of the Peripheral Spatiotemporal Response Pattern: A Potential New Signal-Processing Strategy
Authors: Shi Lu-Feng , Carney Laurel H. , Doherty Karen A.
Published: May 2007

The purpose of this paper is to introduce a new signal-processing strategy, spatiotemporal pattern correction (SPC), that is based on our knowledge of the level-dependent temporal response properties of auditory nerve fibers in normal and impaired ears. In normal-hearing listeners, tuning is sharp for low-level inputs and broadens as input level increases. When peripheral filters change their shape with input level, the phase properties of the filters and the latency of the filter’s response also change. However, in listeners with hearing loss, tuning is broad for both low- and high-level inputs. Thus, there is little change in the phase properties of the filters for different input levels. The SPC strategy manipulates the temporal aspects of different frequency channels of sounds in an attempt to “correct” for this abnormal spatiotemporal response pattern of the impaired ear. Quality judgments and intelligibility measures of speech processed at various SPC strengths were obtained from a small group of normal-hearing listeners and listeners with hearing loss. In general, listeners with hearing loss preferred sentences with some degree of SPC processing, whereas normal-hearing listeners preferred unprocessed sentences. Benefit from SPC on the nonsense syllable test varied greatly across phonemes and listeners. A more comprehensive study of listeners with different degrees and configurations of hearing loss is needed to determine the amount of SPC benefit.
Guidelines for Statistical Analysis of Percentage of Syllables Stuttered Data
Authors: Jones Mark , Onslow Mark , Packman Ann , Gebski Val
Published: May 2007

Purpose

The purpose of this study was to develop guidelines for the statistical analysis of percentage of syllables stuttered (%SS) data in stuttering research.

Method

Data on %SS from various independent sources were used to develop a statistical model to describe this type of data. On the basis of this model, %SS data were simulated with varying means, standard deviations, and sample sizes. Four methods for analyzing %SS were compared.

Results

Results suggested that %SS data can be adequately modeled with a gamma distribution. Simulations based on a gamma distribution showed that all 4 analysis techniques performed favorably with respect to Type I error except for F. E. Satterthwaite’s (1946)
t
test, which had increased Type I error on two occasions. Power was generally lower for the Wilcoxon–Mann–Whitney test compared with the other methods. Analysis of variance (ANOVA) performed on square-root-transformed data performed adequately under all scenarios, but ANOVA performed on nontransformed data and Satterthwaite’s
t
test performed poorly when sample sizes were small or when sample sizes and variances of the groups were markedly different.

Conclusions

Standard techniques such as
t
test and ANOVA are appropriate for most analysis scenarios with %SS data. Two occasions when this is not the case are when sample size is small, with fewer than 20 in each group, or when sample sizes and variances of the groups are markedly different. Under these circumstances, analyses should be based on standard methods, with a suitable transformation performed prior to analysis.
A Comparison of Oral Structure and Oral-Motor Function in Young Males With Fragile X Syndrome and Down Syndrome
Authors: Barnes Elizabeth F. , Roberts Joanne , Mirrett Penny , Sideris John , Misenheimer Jan
Published: May 2007

This study compared the oral structure and oral-motor skills of 59 boys with fragile X syndrome (FXS), 34 boys with Down syndrome (DS), and 36 developmentally similar typically developing (TD) boys. An adaptation of the J. Robbins and T. Klee (1987) Oral Speech Motor Protocol was administered to participants and their scores on measures of oral structure and accuracy on speech motor and oral-motor tasks were analyzed. Boys with FXS scored lower than TD boys on oral structure, most oral function tasks, and all speech function tasks. Boys with DS scored lower than boys with FXS and TD boys on oral structure, and lower than TD boys on 1 oral function task and all speech function tasks. Boys with FXS and TD boys scored higher on speech function than oral function tasks, while boys with DS scored higher on oral function than speech function tasks. Boys with FXS and boys with DS repeated single syllable words with greater accuracy than multiple syllable words, while the TD boys produced both types of words with equal accuracy. These results suggest that boys with FXS and boys with DS exhibit atypical oral structure and motor function, yet differ in specific oral-motor patterns.
The Relationship Between Phonological Memory, Receptive Vocabulary, and Fast Mapping in Young Children With Specific Language Impairment
Authors: Gray Shelley
Published: May 2007

Purpose

This study assessed the fast mapping performance of children with specific language impairment (SLI) across the preschool to kindergarten age span in relation to their phonological memory and vocabulary development.

Method

Fifty-three children diagnosed with SLI and 53 children with normal language (NL) matched for age and gender (30 three-year-olds, 18 four-year-olds, 28 five-year-olds, and 30 six-year-olds) participated. Children’s phonological memory was assessed using nonword repetition and digit span tasks. Receptive vocabulary was assessed using the Peabody Picture Vocabulary Test—III. Children learned the names for 8 objects during 2 fast mapping tasks.

Results

Overall, the NL group demonstrated significantly better performance on phonological memory and vocabulary measures across the age span; however, performance on the fast mapping task differed significantly only at age 5. Phonological memory and existing receptive vocabulary did not predict fast mapping ability.

Conclusions

The phonological memory skills of preschoolers with NL and SLI followed a similar developmental pattern, but the SLI group consistently scored significantly lower than the NL group. Overall, the NL group showed significantly better receptive vocabulary, with evidence that between-group differences increased at age 6. Neither short-term phonological memory nor receptive vocabulary predicted fast mapping comprehension or production performance, even though both have been shown to correlate with later stages of word learning.
Nonword Repetition: A Comparison of Tests
Authors: Archibald Lisa M. D. , Gathercole Susan E.
Published: May 2007

Purpose

This study compared performance of children on 2 tests of nonword repetition to investigate the factors that may contribute to the well-documented nonword repetition deficit in specific language impairment (SLI).

Method

Twelve children with SLI age 7 to 11 years, 12 age-matched control children, and 12 control children matched for language ability completed 2 tests of nonword repetition: the Children’s Test of Nonword Repetition (CNRep) and the Nonword Repetition Test (NRT).

Results

The children with SLI performed significantly more poorly on both tests than typically developing children of the same age. The SLI group was impaired on the CNRep but not the NRT relative to younger children with similar language abilities when adjustments were made for differences in general cognitive ability. The children with SLI repeated the lengthiest nonwords and the nonwords containing consonant clusters significantly less accurately than the control groups.

Conclusion

The evidence suggests that the nonword repetition deficit in SLI may arise from a number of factors, including verbal short-term memory, lexical knowledge, and output processes.
The Effect of Word Frequency on Noun and Verb Definitions: A Developmental Study
Authors: Marinellie Sally A. , Chan Yen-Ling
Published: May 2007

Purpose

Word frequency has profound effects in word recognition and production tasks. Here the influence of word frequency on definitions was investigated, and it was hypothesized that word frequency would have significant influence on responses provided for definitions of nouns and verbs.

Method

Students from Grades 4, 7, 10, and college wrote definitions for high- and low-frequency nouns and verbs and rated their familiarity with the stimulus words. In the noun study, definitions were coded with the semantic response categories “use/purpose,” “description,” “association/relation,” “partial explanation,” “explanation,” and “error.” “Partial explanation” and “explanation” responses were subcategorized to code for use of critical attributes of meaning and class terms. In the verb study, definitions were coded for “synonym,” “association/relation,” “class,” “partial explanation,” “explanation,” and “error.”

Results

Results indicated that certain response categories (such as a class term or a critical attribute) were more characteristic in definitions of high- compared with low-frequency words, whereas responses (such as nonspecific class) were more characteristic in low- compared with high-frequency words. In addition, certain response categories increased with age (such as use of class terms and critical attributes), while errors decreased with age. Familiarity ratings served to validate the high- and low- frequency nature of the stimulus words.

Conclusions

In general, word frequency had a significant impact on word definitions. Implications are discussed with respect to word familiarity, representation in the mental lexicon, acquisition of word meaning, and shared linguistic knowledge.
Teachers and Laypersons Discern Quality Differences Between Narratives Produced by Children With or Without SLI
Authors: Newman Robyn M. , McGregor Karla K.
Published: May 2007

Purpose

To examine the functional impact of specific language impairment (SLI). Specific goals were to determine whether (a) subjective ratings of narrative quality differentiate children with SLI from their normally developing (ND) age-mates, (b) laypersons and teachers differ in their ratings of narrative quality, (c) objective measures confirm previously reported problems in narration among children with SLI, and (d) objective measures of narrative structure and quality ratings relate.

Method

Twenty-seven laypersons and 21 teachers used interval scaling to rate the quality of narratives produced by 20 5–7-year-olds, 10 with SLI and 10 ND age-mates. The narratives were also analyzed objectively for fluency, length, sentence-level syntax, and story grammar and themes.

Results

Subjective ratings differentiated the SLI and ND groups with 70% nonoverlap. No differences were observed between the laypersons' and teachers' numeric ratings; however, laypersons reported that they paid more attention to the “sparkle” or charm of the narratives. Objective measures of story length, grammaticality, and thematic development differentiated SLI and ND groups. Mean length of C-unit and number of thematic units positively predicted quality ratings.

Clinical implications

Intervention efforts aimed specifically at improving the quality of these children’s oral narration may focus on increasing length, grammatical accuracy, and story development. Future clinical and research efforts aimed at addressing the broader functional impact of SLI are also critical given that the manifestations of SLI are noticeable to both teachers and laypersons.
Stability of Low-Frequency Residual Hearing in Patients Who Are Candidates for Combined Acoustic Plus Electric Hearing
Authors: Yao Wai Na , Turner Christopher W. , Gantz Bruce J.
Published: May 2007

The purpose of this study was to investigate the stability over time of low-frequency auditory thresholds to better determine if the new technique of using a short-electrode cochlear implant that preserves residual low-frequency acoustic hearing can be a long-term solution for those with severe-to-profound hearing loss at high frequencies. The present study determined the long-term rate of decline in acoustic hearing in patients who have a preexisting hearing loss yet have not been implanted with a cochlear implant. A retrospective analysis of patients' audiograms that fit into the range for candidacy for the short-electrode device was performed to calculate the rate of change of threshold over time. The analysis of adult patients' data indicated that there was an average of only 1.05 dB hearing deterioration per year in the low frequencies and that presbycusis accounted for approximately one third to one half of this decline. The average deterioration of hearing threshold for pediatric patients was 1.2 dB per year; however, the rates of change in pediatric patients were considerably more variable (across individuals and across frequencies) than in adults. These data provide support for the idea that the short-electrode cochlear implant may be a practical solution for most adults in the long run, but this may not be the case for all pediatric patients.
The Development of Temporal Resolution: Between-Channel Gap Detection in Infants and Adults
Authors: Smith Nicholas A. , Trainor Laurel J. , Shore David I.
Published: May 2007

Purpose

Infants have a good ability to detect brief silent gaps between 2 short identical sound markers (within-channel gap detection), with thresholds between 2 and 11 ms. The present experiment traces the development of temporal resolution for between-channel gaps (i.e., gaps delineated by spectrally disparate markers). This ability appears crucial for the perception of complex stimuli such as speech and is thought to reflect more central auditory processing.

Method

Infants age 6–7.5 months and adults were tested in a between-channel gap detection task using a conditioned head-turn procedure. Gaps were marked by 1- and 4-kHz Gaussian-enveloped sine-tone markers.

Results

Infant gap thresholds were between 30 and 40 ms under conditions in which adult thresholds were between 10 and 20 ms.

Conclusions

Unlike within-channel gap detection, the central temporal processing required for between-channel gap detection is still immature at 6 months of age.
The Dimensionality of Language Ability in School-Age Children
Authors: Tomblin J. Bruce , Zhang Xuyang
Published: May 2007

Purpose

This study asked if children’s performance on language tests reflects different dimensions of language and if this dimensionality changes with development.

Method

Children were given standardized language batteries at kindergarten and at second, fourth, and eighth grades. A revised modified parallel analysis was used to determine the dimensionality of these items at each grade level. A confirmatory factor analysis was also performed on the subtest scores to evaluate alternate models of dimensionality.

Results

The revised modified parallel analysis revealed a single dimension across items with evidence of either test specific or language area specific minor dimensions at different ages. The confirmatory factor analysis tested models involving modality (receptive or expressive) and domain (vocabulary or sentence use) against a single-dimension model. The 2-dimensional model involving domains of vocabulary and sentence use fit the data better than the single-dimensional model; however, the single-dimension model also fit the data well in the lower grades.

Conclusions

Much of the variance in standardized measures of language appears to be attributable to a single common factor or trait. There is a developmental trend during middle childhood for grammatical abilities and vocabulary abilities to become differentiated. These measures do not provide differential information concerning receptive and expressive abilities.
Effects of Acoustic Manipulation on the Real-Time Inflectional Processing of Children With Specific Language Impairment
Authors: Montgomery James W. , Leonard Laurence B.
Published: May 2007

Purpose

This study reports the findings of an investigation designed to examine the effects of acoustic enhancement on the processing of low-phonetic-substance inflections (e.g., 3rd-person singular -
s,
possessive -
s
) versus a high-phonetic-substance inflection (e.g., present progressive -
ing
) by children with specific language impairment (SLI) in a word recognition, reaction time (RT) processing task. The effects of acoustic enhancement on the processing of the same morphemes as well as an additional morpheme (comparative -
er
) were examined in an offline grammaticality judgment task. The grammatical function of 1 of the higher-phonetic-substance inflections, -
ing,
was presumed to be hypothesized relatively early by children; the function of the other, -
er,
was presumed to be hypothesized relatively late.

Method

Sixteen children with SLI (age

M

= 9 years;0 months) and 16 chronological age (CA; age

M

= 8;11) children participated. For both tasks, children listened to sentences containing the target morphemes as they were produced naturally (natural condition) or with acoustic enhancement (enhanced condition).

Results

On the RT task, the children with SLI demonstrated RT sensitivity only to the presence of the high-substance inflection, irrespective of whether it was produced naturally or with enhancement. Acoustic enhancement had no effect on these children’s processing of low-substance inflections. The CA children, by contrast, showed sensitivity to low-substance inflections when they were produced naturally and with acoustic enhancement. These children also showed sensitivity to the high-substance inflection in the natural condition, but in the enhanced condition they demonstrated significantly slower RT. On the grammaticality judgment task, the children with SLI performed worse than the CA children overall and showed especially poor performance on low-substance inflections. Acoustic enhancement had a beneficial effect on the inflectional processing of the children with SLI, but it had no effect on CA children.

Conclusion

The findings are interpreted to suggest that the reduced language processing capacity of children with SLI constrains their ability to process low-substance grammatical material in real time. This factor should be considered along with any difficulty that might be attributable to the grammatical function of the inflection.
The Genetic Bases of Speech Sound Disorders: Evidence From Spoken and Written Language
Authors: Lewis Barbara A. , Shriberg Lawrence D. , Freebairn Lisa A. , Hansen Amy J. , Stein Catherine M. , Taylor H. Gerry , Iyengar Sudha K.
Published: May 2007

The purpose of this article is to review recent findings suggesting a genetic susceptibility for speech sound disorders (SSD), the most prevalent communication disorder in early childhood. The importance of genetic studies of SSD and the hypothetical underpinnings of these genetic findings are reviewed, as well as genetic associations of SSD with other language and reading disabilities. The authors propose that many genes contribute to SSD. They further hypothesize that some genes contribute to SSD disorders alone, whereas other genes influence both SSD and other written and spoken language disorders. The authors postulate that underlying common cognitive traits, or endophenotypes, are responsible for shared genetic influences of spoken and written language. They review findings from their genetic linkage study and from the literature to illustrate recent developments in this area. Finally, they discuss challenges for identifying genetic influence on SSD and propose a conceptual framework for study of the genetic basis of SSD.
Phonological Abilities of Hearing-Impaired Cantonese-Speaking Children With Cochlear Implants or Hearing Aids
Authors: Law Zoe W. Y. , So Lydia K. H.
Published: May 2007

Purpose

This article examined the phonological skills of 2 groups of Cantonese-speaking children with prelingual, profound bilateral hearing loss. The phonological abilities of 7 children fitted with hearing aids were compared with the abilities of 7 children who wore cochlear implants.

Method

Participants in each group ranged in age from 5;1 to 6;4 years. The participants were asked to name 57 pictures and retell 2 stories. Phonological abilities were described in terms of the participants' phonological units and the phonological processes used. The participants' perception of single words was assessed using a Cantonese phonology test that includes tonal, segmental, and semantic distracters.

Results

All except 1 participant had incomplete phonetic repertories. All participants showed complete vowel and tone inventories. The study group used both developmental rules and nondevelopmental phonological rules. For perception of single words, participants chose the target word most often. The cochlear implant users had a significantly higher percentage correct score for consonant production than hearing aid users.

Conclusions

The prediction that Cantonese children wearing cochlear implants would have better phonological skills than children having hearing aids with a similar degree of hearing loss was confirmed. Cochlear implant usage appeared to promote consonant feature production development to a greater degree than did the use of a hearing aid.
Reaction Times of Normal Listeners to Laryngeal, Alaryngeal, and Synthetic Speech
Authors: Evitts Paul M. , Searl Jeff
Published: May 2007

The purpose of this study was to compare listener processing demands when decoding alaryngeal compared to laryngeal speech. Fifty-six listeners were presented with single words produced by 1 proficient speaker from 5 different modes of speech: normal, tracheosophageal (TE), esophageal (ES), electrolaryngeal (EL), and synthetic speech (SS). Cognitive processing load was indexed by listener reaction time (RT). To account for significant durational differences among the modes of speech, an RT ratio was calculated (stimulus duration divided by RT). Results indicated that the cognitive processing load was greater for ES and EL relative to normal speech. TE and normal speech did not differ in terms of RT ratio, suggesting fairly comparable cognitive demands placed on the listener. SS required greater cognitive processing load than normal and alaryngeal speech. The results are discussed relative to alaryngeal speech intelligibility and the role of the listener. Potential clinical applications and directions for future research are also presented.
Effects of Training on Speech Recognition Performance in Noise Using Lexically Hard Words
Authors: Burk Matthew H. , Humes Larry E.
Published: May 2007

Purpose

This study examined how repeated presentations of lexically difficult words within a background noise affect a listener’s ability to understand both trained (lexically difficult) and untrained (lexically easy) words in isolation and within sentences.

Method

In the 1st experiment, 9 young listeners with normal hearing completed a short-term auditory training protocol (5 hr) while 8 other young listeners with normal hearing completed a similar protocol lasting about 15 hr in the 2nd experiment. All training made use of multiple talkers and was in a closed-set condition. Feedback was provided on a trial-to-trial basis and consisted of either orthographic or orthographic and auditory feedback. Performance on both the trained and untrained words in isolation and within sentences was measured pre- and posttraining.

Results

Listeners' performance improved significantly for the trained words in an open and closed-set condition, as well as the untrained words in the closed-set condition. Although there was no mean improvement in the number of keywords identified within sentences posttraining, 50% of the listeners who completed the long-term training showed improvement beyond the 95% critical difference.

Conclusions

With enough training on isolated words, individual listeners can generalize knowledge gained through isolated word training to the recognition of lexically similar words in running speech.
The Relationship Between Nonverbal Cognitive Functions and Hearing Loss
Authors: Zekveld Adriana A. , Deijen Jan Berend , Goverts S. Theo , Kramer Sophia E.
Published: May 2007

Purpose

This study investigated the relationship between hearing loss and memory and attention when nonverbal, visually presented cognitive tests are used.

Method

Hearing loss (pure-tone audiometry) and IQ were measured in 30 participants with mild to severe hearing loss. Participants performed cognitive tests of pattern recognition memory, sustained visual attention, and spatial working memory. All cognitive tests were selected from the Cambridge Neuropsychological Test Automated Battery (CANTAB expedio; Cambridge Cognition Ltd., 2002). Regression analyses were performed to examine the relationship between hearing loss and these cognitive measures of memory and attention when controlling for age and IQ.

Results

The data indicate that hearing loss was not associated with decreased performance on the memory and attention tests. In contrast, participants with more severe hearing loss made more use of an efficient strategy during performance on the spatial working memory subtest. This result might reflect the more extensive use of working memory in daily life to compensate for the loss of speech information.

Conclusions

The authors conclude that the use of nonverbal tests is essential when testing cognitive functions of individuals with hearing loss.
Predictors of Expressive Vocabulary Growth in Children With Autism
Authors: Smith Veronica , Mirenda Pat , Zaidman-Zait Anat
Published: May 2007

Purpose

The purpose of this exploratory study was to examine the variability and predictors of expressive vocabulary development in children with autism and very delayed language.

Method

This study involved 35 children with autism whose initial chronological ages were between 20 and 71 months and whose initial expressive vocabularies were less than 60 words. Their expressive vocabularies were measured at baseline and at 6, 12, and 24 months following the start of intervention using the MacArthur–Bates Communicative Developmental Inventory (L. Fenson et al., 1993).

Results

A cluster analysis revealed 4 distinct patterns of expressive vocabulary development over 2 years. The number of words said, the presence of verbal imitation skills and pretend play skills with objects, and the number of gestures to initiate joint attention at baseline were all associated with the cluster of children who demonstrated the most rapid expressive vocabulary growth over time. The 2 clusters of children who demonstrated the least vocabulary growth had the most significant developmental delays and autism severity at 6 months, but not at baseline.

Conclusions

This study confirms the heterogeneity in language development in young children with autism and, consistent with other reports, confirms that specific prelinguistic skills are predictive of development.
Profiles of Vocal Development in Young Cochlear Implant Recipients
Authors: Ertmer David J. , Young Nancy M. , Nathani Suneeti
Published: May 2007

Purpose

The main purpose of this investigation was to examine the effects of cochlear implant experience on prelinguistic vocal development in young deaf children.

Procedure

A prospective longitudinal research design was used to document the sequence and time course of vocal development in 7 children who were implanted between 10 and 36 months of age. Speech samples were collected twice before implant activation and on a monthly basis thereafter for up to 2 years. Children’s vocalizations were classified according to the levels of the Stark Assessment of Early Vocal Development—Revised (SAEVD–R; S. Nathani, D. J Ertmer, & R. E. Stark, 2006).

Results

The main findings were (a) 6 of 7 children made advancements in vocal development after implantation; (b) children implanted between 12 and 36 months progressed through SAEVD–R levels in the predicted sequence, whereas a child implanted at a younger age showed a different sequence; (c) milestones in vocal development were often achieved with fewer months of hearing experience than observed in typically developing infants and appeared to be influenced by age at implantation; and (d) in general, children implanted at younger ages completed vocal development at younger chronological ages than those implanted later in life. Specific indicators of benefit from implant use were also identified.

Conclusion

The time course of vocal development in young cochlear implant recipients can provide clinically useful information for assessing the benefits of implant experience. Studies of postimplantation vocal development have the potential to inform theories of spoken language development.
The Preschool Repetition Test: An Evaluation of Performance in Typically Developing and Clinically Referred Children
Authors: Chiat Shula , Roy Penny
Published: May 2007

Purpose

To determine the psychometric properties of the Preschool Repetition (PSRep) Test (Roy & Chiat, 2004), to establish the range of performance in typically developing children and variables affecting this performance, and to compare the performance of clinically referred children.

Method

The PSRep Test comprises 18 words and 18 phonologically matched nonwords systematically varied for length and prosodic structure. This test was administered to a typical sample of children aged 2;0–4;0 (
n
= 315) and a clinic sample of children aged 2;6–4;0 (
n
= 168), together with language assessments.

Results

Performance in the typical sample was independent of gender and socioeconomic status but was affected by age, item length, and prosodic structure and was moderately correlated with receptive vocabulary. Performance in the clinic sample was significantly poorer but revealed similar effects of length and prosody and similar relations to language measures overall, with some notable exceptions. Test–retest reliability and interrater reliability were high.

Conclusion

The PSRep Test is a viable and informative test. It differentiates within and between typical and clinic samples of children and reveals some unusual profiles within the clinic sample. These findings lay the foundations for a follow-up study of the clinic sample for investigation of the predictive value of the test.
Discourse Skills of Boys With Fragile X Syndrome in Comparison to Boys With Down Syndrome
Authors: Roberts Joanne , Martin Gary E. , Moskowitz Lauren , Harris Adrianne A. , Foreman Jamila , Nelson Lauren
Published: May 2007

Purpose

This study compared the conversational discourse skills of boys who have fragile X syndrome with and without autism spectrum disorder (ASD) with those of boys with Down syndrome and boys who are typically developing.

Method

Participants were boys who have fragile X syndrome with (n= 26) and without (n= 28) ASD, boys with Down syndrome (n= 29), and boys who are typically developing (n= 22). Turns during an examiner–child interaction consisting of structured and semistructured activities were coded for the boys' ability to maintain a topic of conversation and the frequency of perseveration.

Results

The results revealed that boys who had both fragile X and ASD produced significantly more noncontingent discourse than did boys who had only fragile X, boys with Down syndrome, or typically developing boys. This finding was observed regardless of whether the topic was maintained or changed and whether the turn type was a response or initiation. Regardless of autism status, boys with fragile X used more perseveration than did boys in the other groups.

Conclusion

These findings suggest that some aspects of the conversational discourse difficulties attributed to fragile X syndrome may be a function of the high rate of comorbidity between fragile X and autism, whereas some difficulties may be characteristic of fragile X syndrome.
Generics' Appeal to Innovative Pharma
Authors: Sommerfeld Thimo L.
Published: April 2007

Selling innovative drugs and generic drugs is as different as selling rockets and sneakers. It is, therefore, not surprising that innovative pharma companies have difficulties in developing strategies for entering and exploiting selected generic markets. In spite of barriers to entry, their interest in specific generic segments is definitely high. And we do believe that this interest will result in increasing generic activity of innovative pharma players — even if selling sneakers requires building new capabilities for rocket traders.
Study of the photoluminescence of phosphorus-doped p-type ZnO thin films grown by radio-frequency magnetron sputtering
Authors: Hwang Dae-Kue , Kim Hyun-Sik , Lim Jae-Hong , Oh Jin-Yong , Yang Jin-Ho , Park Seong-Ju , Kim Kyoung-Kook , Look D. C. , Park Y. S.
Published: May 2007

Phosphorus-doped p-type ZnO thin films were grown on sapphire by radio-frequency magnetron sputtering. The photoluminescence (PL) spectra revealed an acceptor bound exciton peak at 3.355 eV and a conduction band to the acceptor transition caused by a phosphorus related level at 3.310 eV. A study of the dependence of the excitation laser power density and temperature on the characteristics of the PL spectra suggests that the emission lines at 3.310 and 3.241 eV can be attributed to a conduction band to the phosphorus-related acceptor transition and a donor to the acceptor pair transition, respectively. The acceptor energy level of the phosphorus dopant was estimated to be located 127 meV above the valence band.
Silicon carbide nanotube tips: Promising materials for atomic force microscopy and/or scanning tunneling microscopy
Authors: Mavrandonakis Andreas , Froudakis George E. , Andriotis Antonis , Menon Madhu
Published: May 2007

Using ab initio techniques we examine the structural properties and energetics of novel nanotip and nanocone materials based on silicon carbide nanotubes. The effect of various structural and topological defects on the highest occupied molecular orbital (HOMO)–lowest unoccupied molecular orbital (LUMO) gap and the stability of these tips are investigated. The HOMO-LUMO gaps range from zero to 2.0eV due to the defects, providing possible applications in band gap engineering. These tips which combine the elastic and mechanical properties of nanotubes with the stiffness of silicon carbide materials can find applications as atomic force microscopy and scanning tunneling microscopy probes.
Field emission studies on well adhered pulsed laser deposited LaB6 on W tip
Authors: Late Dattatray J. , More Mahendra A. , Joag Dilip S. , Misra Pankaj , Singh B. N. , Kukreja Lalit M.
Published: May 2007

Lanthanum hexaboride films have been deposited on a tungsten tip by pulsed laser deposition technique. The field emission studies have been performed in the conventional field emission geometry. The Fowler-Nordheim plot obtained from the current-voltage characteristic is found to be linear in accordance with the quantum mechanical tunneling phenomenon. A current density of 1.2×104A∕cm2 is drawn from the deposited tip. The field enhancement factor is calculated to be 5537cm−1, indicating that the field emission is from nanoscale protrusions present on emitter surface. The emission current-time plots show the very good stability of the emitter.
Dichroism of diamond grains by a polarization modulated near field optical setup
Authors: Micheletto Ruggero , Kawakami Yoichi , Manfredotti Claudio , Garino Yiuri , Allegrini Maria
Published: May 2007

Diamond grown by chemical vapor deposition (CVD) was investigated using a polarization modulated scanning near field optical microscope. The authors found that the luminescence has spatial inhomogeneities and it is partially polarized. Confined emission shows differences in polarization angle up to 90°. The study reveals a peculiar confined dichroic behavior in CVD materials and suggests that local crystal aggregates play a role in it.
Modification to the Newton-Laplace formula of sound velocity at high pressure
Authors: Jiu-Xun Sun , Fu-Qian Jing , Qiang Wu , Ling-Cang Cai
Published: May 2007

The Newton-Laplace (NL) formula of sound velocity is shown being invalid at high pressure, and a modified formula is derived based on the Rankine-Hugoniot relations. The derivation shows that the transmission of sound should be a process satisfying the energy conservation condition instead of the adiabatic condition in the NL formula. The agreement of equations of state for metallic liquids deduced from sound velocity data through the modified formula with the direct experimental P-V data is evidently improved as compared with that deduced through the NL formula.
Enhanced Raman gain coefficients and bandwidths in P2O5 and WO3 added tellurite glasses for Raman gain media
Authors: Jose Rajan , Ohishi Yasutake
Published: May 2007

The Raman gain coefficient and bandwidth of tellurite glasses have been tailored by systematically adding WO3 and P2O5 in a TeO2–BaO–SrO–Nb2O5 glass system. The Raman gain coefficients of the resultant glasses were obtained from spontaneous Raman scattering experiments using a 633nm laser. The glasses developed here showed the widest gain bandwidths so far achieved in tellurite glasses while maintaining higher gain coefficients. The gain bandwidths of these glasses were more than twice that of a conventional tellurite-based glass and 70% larger than that of the silica glass.
Large external ΔT and cooling power densities in thin-film Bi2Te3-superlattice thermoelectric cooling devices
Authors: Bulman G. E. , Siivola E. , Shen B. , Venkatasubramanian R.
Published: May 2007

Experimental I-V-Tc-ΔT data of thin-film superlattice thermoelectric modules is used to determine the internal ΔT, cross-plane Seebeck coefficient, effective thermal interface resistance, device ZT, and Qmax. We demonstrate 55K of external cooling at 300K (Tcmin=244.8K), with an estimated heat pumping capacity of 128W∕cm2. The average ZT300 for the best superlattice devices is 0.75, compared to 0.66 for a bulk BixSb2−xTe3∕Bi2SexTe3−x device. Our model indicates a significantly higher internal ΔT occurs across the active thermoelectric element, which was verified using buried thermocouples.
Influence of the antiphase domain distribution on the magnetic structure of magnetite thin films
Authors: Wei J. D. , Knittel I. , Hartmann U. , Zhou Y. , Murphy S. , Shvets I. V. , Parker F. T.
Published: May 2007

A long-range ordered magnetic domain structure was found in magnetitelike (Fe3−δO4, δ≈0.03) thin films prepared by molecular beam epitaxy on MgO (100) substrates. The stripelike magnetic domain structure arising after suitable postprocessing differs significantly from earlier observations. The field-dependent domain structure was investigated by magnetic force microscopy in external magnetic fields. The magnetic domain structure results from a moderate perpendicular anisotropy. The domain structure is pinned, and the pinning centers arise from the magnetite antiphase domain structure.
Real-time optical spectroscopy study of solid-phase crystallization in hydrogenated amorphous silicon
Authors: Stradins P. , Young D. L. , Yan Y. , Iwaniczko E. , Xu Y. , Reedy R. C. , Branz H. M. , Wang Qi
Published: May 2007

Real-time, in situ, optical reflectance spectroscopy is applied to investigate the kinetics of both random and epitaxial solid-phase crystallization of hydrogenated amorphous silicon annealed between 480 and 620°C, with confirmation of key results by electron microscopy. Changes in the visible and near infrared interference fringes monitor H effusion and bulk phase changes, while the ultraviolet reflection peaks monitor the phase at the film surface. Most H effuses with an activation energy of 1.6eV before crystal nucleation, and crystallite growth occurs with an activation energy of 3.4eV. The authors determine the time-temperature-thickness diagram for random crystallization and solid-phase epitaxy.
Surface plasmon mediated emission in resonant-cavity light-emitting diodes
Authors: Porta P. A. , Harries M. , Summers H. D.
Published: May 2007

In this letter the authors describe a particular method to outcouple in air, via surface plasmons (SPs), optical radiation trapped in leaky waveguide modes of a resonant-cavity light-emitting diode. The deposition of a thin metal layer on the device surface creates SP modes at both the metal-dielectric interfaces. The successive overcoating of the metal layer with a thin polymer film and the roughening of its surface produce outcoupling of radiation trapped in leaky modes via SP modes. Experimental results for polarization resolved reflectivity and emission spectra are in excellent agreement with theoretical predictions.
Pinning-induced round solitons with symmetric nonlinear response for electroactivated optical circuitry
Authors: Pierangelo Angelo , DelRe E. , Palange E. , Ciattoni A. , Garcia Y. , Agranat A. J.
Published: May 2007

The authors experimentally and theoretically study the formation of transient two-dimensional photorefractive spatial solitons in a striated paraelectric potassium lithium tantalate niobate crystal. The partial pinning to the built-in slablike index structures activates an interplay between the linear and nonlinear responses that leads to round solitons through a highly symmetric anisotropic nonlinearity, the means to self-write compact undistorted optical circuitry.
Magnetoelectric CoFe2O4-lead zirconate titanate thick films prepared by a polyvinylpyrrolidone-assisted sol-gel method
Authors: Wan Jian-guo , Zhang Hao , Wang Xiuwei , Pan Dengyu , Liu Jun-ming , Wang Guanghou
Published: May 2007

Magnetoelectric CoFe2O4-PZT (lead zirconate titanate) films as thick as 1μm have been prepared by spin coating using a PZT sol-gel solution containing polyvinylpyrrolidone and CoFe2O4 powder. X-ray diffraction result reveals that there exists no chemical reaction or phase diffusion between the CoFe2O4 and PZT phases. The scanning electron microscopy observation confirms that the composite thick film is crack-free and has a well-defined microstructure. The composite thick films exhibit good magnetic and ferroelectric properties, as well as distinct magnetoelectric coupling behavior. The magnetoelectric coupling mechanism for the present composite thick film is discussed in detail.
Synthesis and magnetic properties of self-organized FeRh nanoparticles
Authors: Ko Hnin Yu Yu , Suzuki Takao
Published: May 2007

Nanoparticles with various compositions of Fe–Rh have been fabricated by a solution phase chemical method and their magnetic properties characterized. After refining and size selection, the average particle size is about 2–5nm by high-resolution transmission electron microscopy observation. From x-ray diffraction results, as-deposited FeRh nanopaticles reveal a typical chemically disordered fcc structure which can be transformed into CsCl-type structure through thermal annealing. Under selected annealing conditions, the coercivities, Hc, for FeRh nanoparticles measured at room temperature are increased, compared with that of their as-deposited states. This increasement in Hc is due to the crystallization of CsCl-type structure after annealing. Nanoparticles of Fe36Rh64 and Fe38Rh62 annealed at 600°C for 6h show the presence of the magnetic phase transitions, while those of Fe75Rh25 particles did not exhibit such a transition.
Induced effects by the substitution of Mg in MgCNi3
Authors: Zhong Guohua , Wang Jianglong , Zeng Zhi , Zheng Xiaohong , Lin Haiqing
Published: May 2007

The electronic structures and magnetic properties induced by the substitution of Mg in MgCNi3 were investigated by performing the first-principles density functional calculations. It is confirmed that AlCNi3, GaCNi3, and InCNi3 are paramagnetic nonsuperconductors resulting from total energy, density of states at Fermi level, and electron-phonon coupling constant. A large peak of density of states lies on the Fermi level, resulting in ferromagnetism rather than superconductivity in NaCNi3. The substitution of dual elements for Mg, such as Al0.5Na0.5CNi3 and Al0.5Li0.5CNi3, was inspected too. Evaluating the electron-phonon coupling interaction, the possible superconductivity exists in near ferromagnetic Al0.5Na0.5CNi3.
Structural and magnetic properties of Mn-doped CuO thin films
Authors: Zhu Hao , Zhao Fan , Pan Liqing , Zhang Yaping , Fan Chongfei , Zhang Yue , Xiao John Q.
Published: May 2007

Highly (111) oriented Mn(6.6%–29.8%) doped CuO thin films have been fabricated on thermally oxidized silicon substrate by radio-frequency magnetron sputtering. X-ray photoelectronic spectroscopy and resistivity studies indicate that both Cu and Mn ions have 2+ valences in the film. Ferromagnetism has been observed for 15.2%–29.8% Mn doped CuO thin film with a transition temperature between 87.0 and 99.5K. The origin of ferromagnetism is analyzed in the context of competition among several interactions between Mn and Cu ions. Highly resistive nature of the films eliminates the carrier mediate mechanisms. The ferromagnetism arises from the ferromagnetic coupling between Mn ions mediated by Cu ions.