bluuebunny/crossref_metadata_2025 huggingface dataset:
The Role of Phonological Opacity in Reading Achievement
Authors: Windsor Jennifer
Published: July 2014

This study investigated the relation among phonological awareness, morphological awareness, and reading achievement in 69 children with and without language-learning disabilities. Children participated in two morphological tasks that assessed skill in identifying the bases and suffixes of phonologically transparent and opaque derivatives. Transparent derivatives preserve the phonological characteristics of the base word (e.g.,
allow-allowable, pure-purist
); opaque derivatives involve stress and/or vowel changes to the base (e.g.,
acid-acidic, flame-flamable
). Children with language-learning disabilities were outperformed by chronological-age peers on each task and showed a level of accuracy similar to that of younger, typically achieving children. Regression analyses were used to determine the proportion of variance in reading accounted for by the morphological tasks beyond that accounted for by age and vocabulary knowledge. Performance with transparent derivatives added a significant, but small, proportion (6.9%) to total variance in word-identification scores and a nonsignificant proportion (2.2%) to passage-comprehension scores. Performance with opaque derivatives added a substantial contribution to word-identification scores (19.9%) and passage-comprehension scores (16.5%) beyond that accounted for by age, vocabulary knowledge, and performance with transparent derivatives. These results suggest that the ability to analyze phonological changes associated with derivation may mediate much of the link between the type of morphological awareness assessed here and reading achievement.
Mechanisms of Discourse Comprehension Impairment After Right Hemisphere Brain Damage
Authors: Tompkins Connie A. , Baumgaertner Annette , Lehman Margaret T. , Fassbinder Wiltrud
Published: July 2014

Normal comprehension skill is linked with the proficiency of a suppression mechanism, which functions to dampen mental activation that becomes irrelevant or inappropriate to a final interpretation. This study investigated suppression and discourse comprehension in adults with right brain damage (RBD). To index suppression function, 40 adults with RBD and 40 without brain damage listened to sentence stimuli that biased the meaning of a sentence-final lexical ambiguity (e.g., SPADE), then judged whether a probe word (e.g., CARDS) fit the overall sentence meaning. Probes represented the contextually inappropriate meanings of the ambiguities and were presented in two conditions: 175 ms and 1000 ms poststimulus. The same probes were used with unambiguous comparison stimuli. Probe judgment response times indicated that only the group without brain damage suppressed inappropriate interpretations over time. In a multiple regression analysis, suppression function added significantly to predicting performance on a general measure of narrative discourse comprehension for participants with RBD. The discussion addresses how suppression deficits may account more broadly for comprehension difficulties after RBD; it also considers several unresolved issues concerning the suppression construct and the suppression deficit hypothesis.
Verbal Working Memory and Sentence Comprehension in Children With Specific Language Impairment
Authors: Montgomery James W.
Published: July 2014

In this study we examined the influence of verbal working memory on sentence comprehension in children with SLI. Twelve children with SLI, 12 normally developing children matched for age (CA), and 12 children matched for receptive vocabulary (VM) completed two tasks. In the verbal working memory task, children recalled as many real words as possible under three processing load conditions (i.e., no-load condition; single-load condition, where words were recalled according to physical size of word referents; and dual-load condition, where words were recalled by semantic category and physical size of word referents). In the sentence comprehension task, children listened to linguistically nonredundant (shorter) and linguistically redundant (longer) sentences. Results of the memory task showed that the children with SLI recalled fewer words in the dual-load condition than their CA peers, who showed no condition effect. The SLI and VM groups performed similarly overall, but both groups showed poorer recall in the dual-load condition than in the other conditions. On the sentence comprehension task, children with SLI comprehended fewer sentences of both types than the CA children and fewer redundant sentences relative to themselves and to the VM children. Results were interpreted to suggest that children with SLI (a) have less functional verbal working memory capacity (i.e., ability to coordinate both storage and processing functions) than their CA peers and (b) have greater difficulty managing both their working memory abilities and general processing resources than both age peers and younger children when performing a "complex" off-line sentence processing task.
Multisign Combinations by Children With Intellectual Impairments
Authors: Grove Nicola , Dockrell Julie
Published: July 2014

Research suggests that people with intellectual impairments who use manual signs to augment or substitute for speech rarely progress beyond the stage of single signs and that word order is particularly problematic. However, the majority of studies have focused on experimental tasks, and relatively little is known about spontaneous sign production in naturalistic settings. The present study explored the linguistic development in sign and speech of 10 children who relied on manual signs (the Makaton vocabulary) as their main means of communication. Mean utterance length in sign ranged from 1.0 to 2.5, and analysis of semantic relations, lexical development, and word order suggested that the children had not developed their language beyond MLU Stage I. Examination of their abilities within the modality of sign indicated that some children were able to manipulate features of sign at a sublexical level. The results are discussed in relation to the language input by teachers, and inferences are drawn regarding the underlying modality of linguistic representation in children who use manual signs.
Which One of These Is Not Like the Others? An inter-hospital Study of the Viscosity of Thickened Fluids
Authors: Cichero Julie A. Y. , Jackson Oliver , Halley Peter J. , Murdoch Bruce E.
Published: July 2014

This investigation examined the rheological (viscosity and yield stress) and material property (density) characteristics of the thickened meal-time and videofluorscopy fluids provided by 10 major metropolitan hospitals. Differences in the thickness of thickened fluids were considered as a source of variability and potential hazard for inter-hospital transfers of dysphagic patients. The results indicated considerable differences in the viscosity, density, and yield stress of both meal-time and videofluoroscopy fluids. In theory, the results suggest that dysphagic patients transferred between hospitals could be placed on inappropriate levels of fluid thickness because of inherent differences in the rheology and material property characteristics of the fluids provided by different hospitals. Slowed improvement or medical complications are potential worst-case scenarios for dysphagic patients if the difference between the thick fluids offered by 2 hospitals are extreme. The investigation outlines the most appropriate way to assess the rheological and material property characteristics of thickened fluids. In addition, it suggests a plan of quality improvement to reduce the variability of the thickness of fluids offered at different hospitals.
Digit Span in Individuals With Down Syndrome and in Typically Developing Children
Authors: Seung Hye-Kyeung , Chapman Robin
Published: July 2014

This study explored factors influencing digit span performance in individuals with Down syndrome. The following questions were asked: Is there a deficit in the phonological loop, either in articulatory rehearsal (measured in speaking rate and recall latency) or in the passive store (measured in recall duration)? Is reduced auditory short-term memory associated with a language production deficit? Thirty five adolescents with trisomy 21 Down syndrome were compared to 35 mental-age-matched and 35 language-production-matched controls. There was no group difference in speaking rate. The DS group had shorter digit spans than the MA controls. Language production level accounted for substantial variance in digit span in individuals with Down syndrome.
How Adolescents Comprehend Unfamiliar Proverbs
Authors: Nippold Marilyn A. , Allen Melissa M. , Kirsch Dixon I.
Published: July 2014

Typically achieving students who were 12, 15, and 18 years old (
n
=150) participated in this investigation. The goal was to determine the extent to which students' prior knowledge of the nouns in unfamiliar proverbs would be associated with their ability to comprehend the expressions and how the relationship between word knowledge and proverb comprehension might change during the developmental period from late childhood to late adolescence. Proverbs containing concrete nouns (e.g., "Two captains will sink a
ship
") (concrete proverbs) and those containing abstract nouns (e.g., "
Envy
is destroyed by true
friendship
") (abstract proverbs) were presented in a multiple-choice task designed to examine comprehension of the expressions. Knowledge of the relevant semantic features of each noun was examined in a separate multiple-choice task. Word knowledge was found to be associated with proverb comprehension in all groups—and particularly so in the case of abstract proverbs. The results support a model of proverb comprehension in adolescents that includes bottom-up in addition to top-down processes.
Prescribed Clinician-Fit Versus As-Worn Coupler Gain in a Group of Elderly Hearing-Aid Wearers
Authors: Humes Larry E. , Barlow Nancy N. , Garner Carolyn B. , Wilson Dana L.
Published: July 2014

This study reports the prescribed, clinician-fit, coupler gain and the user-adjusted, as-worn coupler gain measured in 55 adults ranging in age from 60 to 83 years (
M
=72.2 years). All participants were fit with linear, output-limiting compression, Class D circuits in full-concha, in-the-ear (ITE) shells. The NAL-R prescription rationale was used to generate target real-ear insertion gain (REIG) and coupler gain values. The clinician-fit gain was measured when the hearing aid was dispensed initially and was found to be a close match to the prescribed coupler gain. Both clinician-fit and as-worn gain were measured subsequently at approximately 2 weeks, 1 month, 6 months, and 1 year after the initial fitting. As-worn gain was measured as soon as the participant returned to the clinic for one of the follow-up visits by simply removing the hearing aids and placing them in the test chamber without any adjustments in volume control. At each follow-up session, the clinician then inspected the hearing aids, evaluated the instruments electroacoustically, readjusted the volume control to the setting used to match the prescribed gain in the initial fit, and measured the clinician-fit coupler gain once again. Results revealed that, despite the capability of the hearing aid to achieve coupler gain that is a close match to the prescribed gain, these users consistently selected as-worn gain that was generally 6–9 dB below that prescribed by the NAL-R formula. Of this 6–9 dB disparity, however, as much as 3–6 dB could be due to binaural summation effects not taken into consideration in the NAL-R prescriptive formula. In addition, 5.4% of the time, the hearing aids were found to be in less than ideal operating condition when removed for the as-worn gain measurements (e.g., weak or dead battery, cerumen occluding the sound bore, telecoil switch in the incorrect position).
Binaural Speech Recognition and the Stenger Effect
Authors: Karsten Sue A. , Turner Christopher W.
Published: July 2014

The present investigation examined the effects of systematically altering the balance between speech presentation levels to the 2 ears of 12 listeners with bilateral asymmetrical sensorineural hearing impairments. Speech-recognition scores for /VCV/ speech stimuli were obtained from each participant in quiet for 9 conditions ranging from monaural poorer ear only to monaural better ear only, with 7 intermediate conditions in which the sound balance between ears was varied in 5-dB steps. High-pass spectral shaping was provided to the poorer ear, and unshaped amplification was provided to the better ear. The results suggested that, as a group, varying the sound level in the better ear within –20 to +10 dB of the centered position did not significantly change the speech recognition for these participants. No evidence of binaural interference was obtained. Findings also showed that in binaural listening situations, the Stenger effect has little influence upon speech-recognition scores. Even when the listeners were unaware of speech being presented to the better ear, their speech-recognition score reflected the better ear's abilities.
Acoustic Duration Changes Associated With Two Types of Treatment for Children Who Stutter
Authors: Riley Glyndon D. , Ingham Janis Costello
Published: July 2014

The purpose of this study was (a) to examine in young children the effects of Speech Motor Training (SMT) on selected temporal acoustic durations considered to be related to speech motor programming, (b) to compare the speech motor effects of that treatment with those of a treatment of childhood stuttering that did not directly incorporate speech motor control training (Extended Length of Utterance [ELU]), and (c) to examine the relation of acoustic duration changes to reduction of stuttering. Twelve children who stutter were recorded while repeating syllable sets /pv/ and /tvke/ before and after SMT (
n
=6) or ELU treatment (
n
=6). Children who did not stutter served as matched reference groups. The syllables beginning with /p/ and /t/ were used as tokens for the acoustic measurement. Five measures served as indicators of temporal aspects of speech motor performance: vowel duration, stop gap duration, voice onset time, stop gap/vowel duration ratio, and total token duration. Results indicated that following SMT there was a significant increase in vowel duration and some reduction in stop gap duration that resulted in significantly reduced stop gap/vowel duration ratios. These acoustic effects were consistent across most participants. The ELU treatment reduced stuttering more than the SMT, but was not accompanied by significant effects on the selected temporal acoustic measures. These findings are compared with previous findings of increased vowel durations associated with fluency enhancement and stuttering treatment. We speculate that the increased vowel durations allow more time for speech motor planning and that stuttering is reduced moderately as a by-product of longer vowel durations. The mechanism(s) by which ELU treatment reduces stuttering did not appear to be captured by the dependent variables measured in this study.
A Comparison of Equal-Appearing Interval Scaling and Direct Magnitude Estimation of Nasal Voice Quality
Authors: Zraick Richard I. , Liss Julie M.
Published: July 2014

Listeners rated the nasality of synthesized vowels using two psychophysical scaling methods (equal-appearing interval scaling and direct magnitude estimation). A curvilinear relationship between equal-appearing interval ratings and direct magnitude estimations of nasality indicated that nasality is a prothetic rather than metathetic dimension. It also was shown that the use of direct magnitude estimation results in nasality ratings that are more consistent and reliable. The results of this experiment are discussed in relation to other studies that have examined the validity and reliability of equal-appearing interval scaling of voice quality. Additionally, there is a discussion of methodological issues for future research and the implications of the findings for clinical and research purposes.
Multidimensional Scaling of Nasal Voice Quality
Authors: Zraick Richard I. , Liss Julie M. , Dorman Michael F. , Case James L. , LaPointe Leonard L. , Beals Stephen P.
Published: July 2014

Listeners judged the dissimilarity of pairs of synthesized nasal voices that varied on 3 dimensions. Separate nonmetric multidimensional scaling (MDS) solutions were calculated for each listener and the group. Similar 3-dimensional solutions were derived for the group and each of the listeners, with the group MDS solution accounting for 83% of the total variance in listeners' judgments. Dimension 1 ("Nasality") accounted for 54% of the variance, Dimension 2 ("Loudness") for 18% of the variance, and Dimension 3 ("Pitch") for 11% of the variance. The 3 dimensions were significantly and positively correlated with objective measures of nasalization, intensity, and fundamental frequency. The results of this experiment are discussed in relation to other MDS studies of voice perception, and there is a discussion of methodological issues for future research.
Predicting Language Outcomes for Young Prelinguistic Children With Developmental Delay
Authors: Calandrella Amy M. , Wilcox M. Jeanne
Published: July 2014

The purpose of this study was to examine potential relationships between children's prelinguistic communication behaviors and subsequent (12 months later) expressive and receptive language outcomes. Participants included 25 toddlers with developmental delay and their mothers. The dyads were observed during natural interactions at 6-month intervals over a 12-month period for a total of 3 observation points (O
1
, O
2
, O
3
). Children's rate of nonverbal behavior that is often perceived as communication by adults was identified at O
1
and O
2
. In the investigation, the children's intentional nonverbal communication acts all included coordinated attention between the communication referent and the adult. The other types of prelinguistic communication behavior, termed gestural indicating behavior and social interaction signals, were produced without coordinated attention to the adult. Receptive and expressive language test scores and spontaneous word productions were analyzed at O
3
and served as outcome measures in regression analyses. Results indicated that rate of intentional nonverbal communication at O
1
was a predictor of spontaneous word productions at O
3
. At O
2
, rate of intentional communication and rate of gestural indicating behavior predicted subsequent language outcomes as measured by the Sequenced Inventory of Communication Development-Revised. The results are consistent with previous findings for intentional nonverbal communication that includes coordinated attention, but additionally demonstrate that prelinguistic behavior lacking coordinated attention also bears a relationship to subsequent language outcome. Discussion of observed patterns focuses on child and adult factors that may motivate the transition from prelinguistic to early symbolic communication.
Accuracy of Metamemory After Traumatic Brain Injury
Authors: Kennedy Mary R.T. , Yorkston Kathryn M.
Published: July 2014

The primary intent of this study was to investigate the metamemory monitoring abilities of adult survivors of at least moderate traumatic brain injury (TBI) during a verbal-learning activity. Eighteen survivors and 18 non-injured control participants made judgment-of-learning (JOL) predictions of their recall ability immediately after studying 3 lists of noun-pairs or after a slight delay. A secondary intent of this study was to determine if verbal retrieval attempts would enhance predictive accuracy. One half of participants made retrieval attempts during the second and third list-learning task, and the other half made retrieval attempts during the third list-learning task only. Measures of the correlation between JOL predictions and recall accuracy revealed that survivors were as accurate as controls when making delayed predictions and were less accurate when making immediate predictions. This occurred regardless of retrieval attempts. Absolute measures that compared mean JOL ratings to overall recall revealed that the survivor group was well-calibrated when making delayed JOL predictions but overestimated when making immediate JOL predictions. The non-injured control group underestimated when making both types of predictions. However, within-group variability was high. These findings are compared to those from studies that investigated metamemory beliefs in which survivors' ratings were compared to family-member ratings. Clinical implications for basing executive decisions about compensatory strategies on delayed and immediate predictions of future recall are discussed. Additionally, a rationale is provided for the use of both relative and absolute measures of predictive accuracy in metamemory studies involving neurological clinical populations.
Lip Muscle Activity Related to Speech Rate and Loudness
Authors: Wohlert Amy B. , Hammen Vicki L.
Published: July 2014

Changes in suprasegmental speech parameters may require adjustments in oral motor control that are reflected in the activity of perioral musculature. In order to evaluate possible patterns of difference, perioral surface electromyographic (EMG) signals were obtained from 20 adults who read a paragraph aloud at habitual rate and at self-judged proportionately slower and faster rates, at habitual loudness and at proportionately softer and louder levels, and in a "precise" manner. EMG amplitude analysis showed significant task effects, with higher average amplitudes for fast, loud, and precise speech and lower average amplitudes for slow and soft speech. These results are compatible with a model of multidimensional reorganization of speech motor control for suprasegmental changes applied to connected speech.
Temporal and Biomechanical Characteristics of Oropharyngeal Swallow in Younger and Older Men
Authors: Logemann Jeri A. , Pauloski Barbara Roa , Rademaker Alfred W. , Colangelo Laura A. , Kahrilas Peter J. , Smith Christina H.
Published: July 2014

As the U.S. population ages, there is increasing need for data on the effects of aging in healthy elderly individuals over age 80. This investigation compared the swallowing ability of 8 healthy younger men between the ages of 21 and 29 and 8 healthy older men between the ages of 80 and 94 during two swallows each of 1 ml and 10 ml liquid. Videofluoroscopic studies of these swallows were analyzed to confirm the absence of swallowing disorders. Biomechanical analysis of each swallow was completed, from which data on temporal, range of motion, and coordination characteristics of the oropharyngeal swallow were taken. Position of the larynx at rest, length of neck, and pattern of hyoid bone movement were also compared between the two groups. None of the younger or older men exhibited any swallowing disorders. The C2 to C4 distance of older men was significantly shorter than that of younger men, and laryngeal position at rest was lower than in younger men but not significantly so. Older men had a significantly longer pharyngeal delay than younger men and significantly faster onset of posterior pharyngeal wall movement in relation to first cricopharyngeal opening. The older men exhibited significantly reduced maximum vertical and anterior hyoid movement as compared to the younger men even when accounting for the difference in C2 to C4 distance in older men. These data support the hypothesis of reduced muscular reserve in the swallows of older men as compared to younger men. Older men also exhibited less width of cricopharyngeal opening than younger men at 10 ml volume, indicating less upper esophageal sphincter flexibility in the swallows of older men. The potential for exercise to improve reserve is discussed. Significant changes in extent of hyoid elevation and duration of cricopharyngeal opening were seen as liquid bolus volume increased.
Verb and Noun Morphology in the Spoken and Written Language of Children With Language Learning Disabilities
Authors: Windsor Jennifer , Scott Cheryl M. , Street Cheryl K.
Published: July 2014

The purpose of this study was to investigate the use of verb and noun morphology in school-age children's spoken and written language. Sixty children, with and without language learning disabilities (LLD), each produced 2 spoken and 2 written language samples. The children's accuracy in using morphemes that mark verb finiteness (regular past tense, 3rd person singular present tense, copula, and auxiliary BE) was compared with their accuracy in using noun morphology (regular plural, possessive, articles). As would be expected, the typically achieving children, who were aged 7 to 12 years, had mastered the verb and noun morphology in spoken and written samples. The children with LLD, aged 10 to 12 years, also showed high accuracy in the spoken samples. On the other hand, they showed substantial difficulty in the written samples with the regular past tense, with errors in 26% of obligatory contexts. However, the children with LLD also had difficulty with the regular plural, with errors in 12% of obligatory contexts. For both the regular past tense and plural, all errors were errors of omission. These results indicate that finiteness marking remains an area of relative difficulty, but perhaps not the only grammatical difficulty, for children with language impairments in the school years.
Factors Affecting Young Children's Use of Pronouns as Referring Expressions
Authors: Campbell Aimee L. , Brooks Patricia , Tomasello Michael
Published: July 2014

Most studies of children's use of pronouns have focused either on the morphology of personal pronouns or on the anaphoric use of pronouns by older children. The current two studies investigated factors affecting children's choice of pronouns as referring expressions—in contrast with their use of full nouns and null references. In the first study it was found that 2.5- and 3.5-year-old children did not use pronouns differentially whether the adult (a) modeled a pronoun or a noun for the target object or (b) did or did not witness the target event (although there was evidence that they did notice and take account of the adult's witnessing in other ways). In the second study it was found that children of this same age (a) do not use pronouns to avoid unfamiliar or difficult nouns but (b) do use pronouns differently depending on the immediately preceding discourse of the experimenter (whether they were asked a specific question such as "What did X do?" or a general question such as "What happened?"). In the case of specific questions, children prefer to use a null reference but use some pronouns as well (almost never using full nouns); in the case of the generic questions, children use pronouns even more often (and use nouns more as well). This finding was corroborated by some new analyses of children's use of pronouns in specific discourse situations in previously published studies. These findings suggest that children's choice of pronouns as referring expressions in early language development is influenced more by the immediately preceding discourse than other kinds of factors.
Multi-Channel Compression and Speech Intelligibility in Industrial Noise
Authors: Dolan Thomas G. , Wonderlick Bret A.
Published: July 2014

This study examined how various forms of compression affect speech intelligibility in moderately high levels of industrial noise. Thirteen listeners with high-frequency sensorineural hearing loss were fit with a digital hearing aid programmed to operate in three modes of compression: compression limiting, compression of low frequencies only (BILL), and compression of high frequencies only (TILL). For each of these conditions, listeners attempted to recognize CID W-22 monosyllabic words delivered in a background of recorded industrial noise. Word recognition was also measured in quiet for the compression-limiting condition. The highest word identification scores were obtained in quiet (80.9%). Of the three conditions in which background noise was present, the mean score was highest for TILL compression (52.4%), and lowest for BILL (39.7%). Representative time-weighted average (TWA) exposures for each of the aided noise conditions were determined by means of a procedure outlined previously by the first author. The projected 8-hour amplified TWA with the hearing aid programmed to the TILL configuration was 94 dBA, whereas TWAs for the linear and BILL configurations were each 104 dBA. Thus, the highest intelligibility and lowest noise exposures were obtained with the aid in the TILL mode.
Perception of Voiceless Fricatives by Normal-Hearing and Hearing-Impaired Children and Adults
Authors: Pittman Andrea L. , Stelmachowicz Patricia G.
Published: July 2014

This study examined the perceptual-weighting strategies and performance-audibility functions of 11 moderately hearing-impaired (HI) children, 11 age-matched normal-hearing (NH) children, 11 moderately HI adults, and 11 NH adults. The purpose was to (a) determine the perceptual-weighting strategies of HI children relative to the other groups and (b) determine the audibility required by each group to achieve a criterion level of performance. Stimuli were 4 nonsense syllables (/us/, /u∫/, /uf/, and /uθ/). The vowel, transition, and fricative segments of each nonsense syllable were identified along the temporal domain, and each segment was amplified randomly within each syllable during presentation. Point-biserial correlation coefficients were calculated using the amplitude variation of each segment and the correct and incorrect responses for the corresponding syllable. Results showed that for /us/ and /u∫/, all four groups heavily weighted the fricative segments during perception, whereas the vowel and transition segments received little or no weight. For /uf/, relatively low weights were given to each segment by all four groups. For /uθ/, the NH children and adults weighted the transition segment more so than the vowel and fricative segments, whereas the HI children and adults weighted all three segments equally low. Performance-audibility functions of the fricative segments of /us/ and /u∫/ were constructed for each group. In general, maximum performance for each group was reached at lower audibility levels for /s/ than for /∫/ and steeper functions were observed for the HI groups relative to the NH groups. A decision theory approach was used to confirm the audibility required by each group to achieve a ≥90% level of performance. Results showed both hearing sensitivity and age effects. The HI listeners required lower levels of audibility than the NH listeners to achieve similar levels of performance. Likewise, the adult listeners required lower levels of audibility than the children, although this difference was more substantial for the NH listeners than for the HI listeners.
SIG 2 Perspectives Vol. 22, No. 1, April 2012
Authors: Helm-Estabrooks Nancy , Whiteside Janet
Published: July 2014

Sorry, this activity is no longer available for CEUs. Visit the SIG 2 page on the
ASHA Store
to see available CE activities.

Use the CE questions PDF here as study questions to guide your Perspectives reading.
SIG 2 Perspectives Vol. 22, No. 4, December 2012
Authors: Threats Travis
Published: July 2014

Sorry, this activity is no longer available for CEUs. Visit the SIG 2 page on the
ASHA Store
to see available CE activities.

Use the CE questions PDF here as study questions to guide your Perspectives reading.
SIG 16 Perspectives Vol. 13, No. 2, August 2012
Authors: Garrett Jennifer Walz
Published: July 2014

Sorry, this activity is no longer available for CEUs. Visit the SIG 16 page on the
ASHA Store
to see available CE activities.

Use the CE questions PDF here as study questions to guide your Perspectives reading.
Drafting a Blueprint for Successful Funding in Schools
Authors: Wheat Kathy , Hall-Mills Shannon , Deppe Janet
Published: July 2014

Purpose:

Securing funding for school based services is challenging in current economic times. Using a DIY (Do-It-Yourself) analogy, this article will help school-based speech-language pathologists (SLPs) and audiologists (AUDs) draft and execute a blueprint plan for obtaining funding to support their services.

Method:

The need for school-based members to self-advocate for funding is illustrated with highlights from a recent survey of school-based SLPs and AUDs. We present a nuts-and-bolts guide to assist with efforts to secure funding for materials, equipment, and technology to best serve students within the school setting.

Conclusion:

Funding goals can be reached by individual SLPs and AUDs as illustrated by a series of funding success stories.
Editorial: Defining materials science: A vision from APL Materials
Authors: MacManus-Driscoll Judith
Published: July 2014

These are exciting times for materials science—a field which is growing more rapidly than any other physical science discipline. More than ever, the field is providing the vital link between science and engineering, between pure and applied. But what is the subject's definition and why is the field ballooning? I address these questions in the context of how APL Materials intends to play a role in advancing this important field. My introspective focus arises as we approach the first year anniversary of APL Materials.
Universal tight binding model for chemical reactions in solution and at surfaces. II. Water
Authors: Lozovoi A. Y. , Sheppard T. J. , Pashov D. L. , Kohanoff J. J. , Paxton A. T.
Published: July 2014

A revised water model intended for use in condensed phase simulations in the framework of the self consistent polarizable ion tight binding theory is constructed. The model is applied to water monomer, dimer, hexamers, ice, and liquid, where it demonstrates good agreement with theoretical results obtained by more accurate methods, such as DFT and CCSD(T), and with experiment. In particular, the temperature dependence of the self diffusion coefficient in liquid water predicted by the model, closely reproduces experimental curves in the temperature interval between 230 K and 350 K. In addition, and in contrast to standard DFT, the model properly orders the relative densities of liquid water and ice. A notable, but inevitable, shortcoming of the model is underestimation of the static dielectric constant by a factor of two. We demonstrate that the description of inter and intramolecular forces embodied in the tight binding approximation in quantum mechanics leads to a number of valuable insights which can be missing from ab initio quantum chemistry and classical force fields. These include a discussion of the origin of the enhanced molecular electric dipole moment in the condensed phases, and a detailed explanation for the increase of coordination number in liquid water as a function of temperature and compared with ice—leading to insights into the anomalous expansion on freezing. The theory holds out the prospect of an understanding of the currently unexplained density maximum of water near the freezing point.
Rotation characteristics during the resonant magnetic perturbation induced edge localized mode suppression on the KSTAR
Authors: Ko Won-Ha , Lee H. H. , Jeon Y. M. , Ida K. , Lee J. H. , Yoon S. W. , Lee K. D. , Bae Y. S. , Oh Y. K. , Kwak J. G.
Published: July 2014

Measuring rotation profiles with a reliable spatial resolution is one of the critical diagnostics in understanding the plasma behavior especially for the edge transport. In the KSTAR experiments, it has been consistently observed from the charge exchange spectroscopy measurements that the magnetic perturbations not only suppresses edge localized modes (ELMs) but also reduces toroidal rotations. In this paper, toroidal velocities of the carbon impurity and their profile evolutions during ELMy and ELM-suppressed phases are presented. The rotation profiles are shown to collapse immediately after an ELM burst and continue to build up until the next burst that accompanies another collapse. Toroidal rotations following the resonant magnetic perturbations applications are observed to be reduced along with the ELMs suppressed.
Hysteresis prediction inside magnetic shields and application
Authors: Morić Igor , De Graeve Charles-Marie , Grosjean Olivier , Laurent Philippe
Published: July 2014

We have developed a simple model that is able to describe and predict hysteresis behavior inside Mumetal magnetic shields, when the shields are submitted to ultra-low frequency (<0.01 Hz) magnetic perturbations with amplitudes lower than 60 μT. This predictive model has been implemented in a software to perform an active compensation system. With this compensation the attenuation of longitudinal magnetic fields is increased by two orders of magnitude. The system is now integrated in the cold atom space clock called PHARAO. The clock will fly onboard the International Space Station in the frame of the ACES space mission.
A simulation assessment of the thermodynamics of dense ion-dipole mixtures with polarization
Authors: Bastea Sorin
Published: July 2014

Molecular dynamics (MD) simulations are employed to ascertain the relative importance of various electrostatic interaction contributions, including induction interactions, to the thermodynamics of dense, hot ion-dipole mixtures. In the absence of polarization, we find that an MD-constrained free energy term accounting for the ion-dipole interactions, combined with well tested ionic and dipolar contributions, yields a simple, fairly accurate free energy form that may be a better option for describing the thermodynamics of such mixtures than the mean spherical approximation (MSA). Polarization contributions induced by the presence of permanent dipoles and ions are found to be additive to a good approximation, simplifying the thermodynamic modeling. We suggest simple free energy corrections that account for these two effects, based in part on standard perturbative treatments and partly on comparisons with MD simulation. Even though the proposed approximations likely need further study, they provide a first quantitative assessment of polarization contributions at high densities and temperatures and may serve as a guide for future modeling efforts.
Drastic reduction in the surface recombination velocity of crystalline silicon passivated with catalytic chemical vapor deposited SiNx films by introducing phosphorous catalytic-doped layer
Authors: Thi Trinh Cham , Koyama Koichi , Ohdaira Keisuke , Matsumura Hideki
Published: July 2014

We improve the passivation property of n-type crystalline silicon (c-Si) surface passivated with a catalytic chemical vapor deposited (Cat-CVD) Si nitride (SiNx) film by inserting a phosphorous (P)-doped layer formed by exposing c-Si surface to P radicals generated by the catalytic cracking of PH3 molecules (Cat-doping). An extremely low surface recombination velocity (SRV) of 2 cm/s can be achieved for 2.5 Ω cm n-type (100) floating-zone Si wafers passivated with SiNx/P Cat-doped layers, both prepared in Cat-CVD systems. Compared with the case of only SiNx passivated layers, SRV decreases from 5 cm/s to 2 cm/s. The decrease in SRV is the result of field effect created by activated P atoms (donors) in a shallow P Cat-doped layer. Annealing process plays an important role in improving the passivation quality of SiNx films. The outstanding results obtained imply that SiNx/P Cat-doped layers can be used as promising passivation layers in high-efficiency n-type c-Si solar cells.
Two-dimensional metamaterial device design in the discrete dipole approximation
Authors: Landy Nathan , Smith David R.
Published: July 2014

We extend the discrete dipole method to enable the analysis and design of two-dimensional magnetoelectric metamaterial devices based on transformation optics. Key to this method is the evaluation of the dipole moments of the metamaterial elements, which can be accomplished within the framework of a rigorous Bloch wave model based on lattice sums. Corrections to the polarizabilities for spatial dispersion and magnetoelectric coupling are included in the formulation of a generalized Clausius-Mossotti relationship. We demonstrate the utility of the extended approach by designing a cloaking structure that shows considerably improved performance over that designed by assuming the standard Clausius-Mossotti relationship between constitutive parameter and polarizability.
Characterization of a Fe/Y2O3 metal/oxide interface using neutron and x-ray scattering
Authors: Watkins E. B. , Kashinath A. , Wang P. , Baldwin J. K. , Majewski J. , Demkowicz M. J.
Published: July 2014

The structure of metal/oxide interfaces is important to the radiation resistance of oxide dispersion-strengthened steels. We find evidence of gradual variations in stoichiometry and magnetization across a Fe/Y2O3 metal/oxide heterophase interface using neutron and x-ray reflectometry. These findings suggest that the Fe/Y2O3 interface is a transitional zone approximately ∼64 Å-thick containing mixtures or compounds of Fe, Y, and O. Our results illustrate the complex chemical and magnetic nature of Fe/oxide interfaces and demonstrate the utility of combined neutron and x-ray techniques as tools for characterizing them.
Modeling of free electronic state density in hydrogenic plasmas based on nearest neighbor approximation
Authors: Nishikawa Takeshi
Published: July 2014

Most conventional atomic models in a plasma do not treat the effect of the plasma on the free-electron state density. Using a nearest neighbor approximation, the state densities in hydrogenic plasmas for both bound and free electrons were evaluated and the effect of the plasma on the atomic model (especially for the state density of the free electron) was studied. The model evaluates the electron-state densities using the potential distribution formed by the superposition of the Coulomb potentials of two ions. The potential from one ion perturbs the electronic state density on the other. Using this new model, one can evaluate the free-state density without making any ad-hoc assumptions. The resulting contours of the average ionization degree, given as a function of the plasma temperature and density, are shifted slightly to lower temperatures because of the effect of the increasing free-state density.
Acoustic emission analysis on tensile failure of steam-side oxide scales formed on T22 alloy superheater tubes
Authors: Huang Jun-Lin , Zhou Ke-Yi , Wang Xin-Meng , Tu Yi-You , Xu Jian-Qun
Published: July 2014

Failure of steam-side oxide scales on boiler tubes can seriously influence the safety of coal-fired power plants. Uniaxial tensile tests employing acoustic emission (AE) monitoring were performed, in this work, to investigate the failure behavior of steam-side oxide scales on T22 alloy boiler superheater tubes. The characteristic frequency spectra of the captured AE signals were obtained by performing fast Fourier transform. Three distinct peak frequency bands, 100-170, 175-250, and 280-390 kHz, encountered in different testing stages were identified in the frequency spectra, which were confirmed to, respectively, correspond to substrate plastic deformation, oxide vertical cracking, and oxide spalling with the aid of scanning electronic microscopy observations, and can thus be used for distinguishing different oxide failure mechanisms. Finally, the critical cracking strain of the oxide scale and the interfacial shear strength of the oxide/substrate interface were estimated, which are the critical parameters urgently desired for modeling the failure behavior of steam-side oxide scales on boiler tubes of coal-fired power plants.
Structure-property relations in amorphous carbon for photovoltaics
Authors: Risplendi Francesca , Bernardi Marco , Cicero Giancarlo , Grossman Jeffrey C.
Published: July 2014

Carbon is emerging as a material with great potential for photovoltaics (PV). However, the amorphous form (a-C) has not been studied in detail as a PV material, even though it holds similarities with amorphous Silicon (a-Si) that is widely employed in efficient solar cells. In this work, we correlate the structure, bonding, stoichiometry, and hydrogen content of a-C with properties linked to PV performance such as the electronic structure and optical absorption. We employ first-principles molecular dynamics and density functional theory calculations to generate and analyze a set of a-C structures with a range of densities and hydrogen concentrations. We demonstrate that optical and electronic properties of interest in PV can be widely tuned by varying the density and hydrogen content. For example, sunlight absorption in a-C films can significantly exceed that of a same thickness of a-Si for a range of densities and H contents in a-C. Our results highlight promising features of a-C as the active layer material of thin-film solar cells.
Magnetism induced by excess electrons trapped at diamagnetic edge-quantum well in multi-layer graphene
Authors: Zhang Xi , Wang Chao , Sun Chang Q , Diao Dongfeng
Published: July 2014

In this paper, we clarified a robust mechanism of magnetism generated by excess electrons captured by edge-quantum well of diamagnetic armchair edges. Consistency between density functional theory calculations and electron cyclotron resonance experiments verified that: (1) Multi-layer armchair nanoribbons are stable with proper amounts of excess electrons which can provide net spin; (2) Since under-coordination induces lattice relaxation and potential well modulation, electrons tend to be trapped at edges; and (3) Neither large amount of excess electrons nor positive charges can induce magnetism. This work shed light on the development of graphene devices in its magnetic applications.
Analytical model for fast-shock ignition
Authors: Ghasemi S. A. , Farahbod A. H. , Sobhanian S.
Published: July 2014

A model and its improvements are introduced for a recently proposed approach to inertial confinement fusion, called fast-shock ignition (FSI). The analysis is based upon the gain models of fast ignition, shock ignition and considerations for the fast electrons penetration into the pre-compressed fuel to examine the formation of an effective central hot spot. Calculations of fast electrons penetration into the dense fuel show that if the initial electron kinetic energy is of the order ∼4.5 MeV, the electrons effectively reach the central part of the fuel. To evaluate more realistically the performance of FSI approach, we have used a quasi-two temperature electron energy distribution function of Strozzi (2012) and fast ignitor energy formula of Bellei (2013) that are consistent with 3D PIC simulations for different values of fast ignitor laser wavelength and coupling efficiency. The general advantages of fast-shock ignition in comparison with the shock ignition can be estimated to be better than 1.3 and it is seen that the best results can be obtained for the fuel mass around 1.5 mg, fast ignitor laser wavelength ∼0.3  micron and the shock ignitor energy weight factor about 0.25.
Control of light diffusion in a disordered photonic waveguide
Authors: Sarma Raktim , Golubev Timofey , Yamilov Alexey , Cao Hui
Published: July 2014

We control the diffusion of light in a disordered photonic waveguide by modulating the waveguide geometry. In a single waveguide of varying cross-section, the diffusion coefficient changes spatially in two dimensions due to localization effects. The intensity distribution inside the waveguide agrees with the prediction of the self-consistent theory of localization. Our work shows that wave diffusion can be efficiently manipulated without modifying the structural disorder.