bluuebunny/crossref_metadata_2025 huggingface dataset:
Equatorward moving auroral signatures of a flow burst observed prior to auroral onset
Authors: Kepko L. , Spanswick E. , Angelopoulos V. , Donovan E. , McFadden J. , Glassmeier K.‐H. , Raeder J. , Singer H. J.
Published: December 2009

We present observations of a substorm that occurred on February 25, 2008. Auroral onset was observed with a multi‐spectral (λ = 427.8, 557.7 and 630.0 nm) and white light all sky imager at Gillam, Canada. An equatorward moving diffuse auroral patch was observed in the λ = 630.0 nm images at least six minutes prior to auroral onset. This form emerged from the background noise poleward of the eventual onset arc and intensified as it moved equatorward. Auroral expansion onset occurred when this form reached the onset arc location. Flows were detected by THEMIS probes P3 (TH‐D) and P4 (TH‐E) near X ∼ −11 RE nearly 90 seconds prior to auroral expansion. A small discrete arc was observed in the λ = 557.7 nm images at the westward and equatorward edge of the diffuse 630.0 nm patch nearly 2 minutes prior to expansion onset, suggesting a field‐aligned current of a substorm current wedge geometry. We conclude that the equatorward moving λ = 630.0 nm diffuse auroral patch was generated by processes associated with an earthward moving flow burst that formed prior to auroral substorm onset.
Experimental evidence for the role of the neutral wind in the development of ionospheric storms in midlatitudes
Authors: Paznukhov V. V. , Altadill D. , Reinisch B. W.
Published: December 2009

This paper presents an analysis of the ionospheric response to geomagnetic storms in the European and North American regions. Ionospheric behavior during the major storms of the last solar maximum (2003–2005) has been analyzed using electron density profiles and foF2 and hmF2 characteristics obtained from the digisonde network. The storm of 24 August 2005 has been investigated most comprehensively. Our analysis provides experimental evidence in support of the ionospheric storm model based on the role of the neutral wind and thermospheric circulation. The main results showing the validity of this mechanism are observations of the ionospheric uplifting preceding both negative and positive storm effects at all locations. Using a latitudinal chain of digisonde stations in the European sector we clearly observed equatorward propagation of the storm disturbance that originated at high latitudes near the auroral oval. It is also shown that traveling atmospheric disturbances played a significant role in the development of the ionospheric storm of 24 August 2005. Attempts are made to determine the general pattern of the dependence of ionospheric storm effects on the local time. The results obtained also support the neutral wind based mechanism for ionospheric storms.
Short‐wavelength turbulence in the solar wind: Linear theory of whistler and kinetic Alfvén fluctuations
Authors: Gary S. Peter , Smith Charles W.
Published: December 2009

There is a debate as to the identity of the fluctuations which constitute the relatively high‐frequency plasma turbulence observed in the solar wind. One school holds that these modes are kinetic Alfvén waves, whereas another opinion is that they are whistler modes. Here linear kinetic theory for electromagnetic fluctuations in homogeneous, collisionless, magnetized plasmas is used to compute two dimensionless transport ratios, the electron compressibility Ce and the magnetic compressibility C for these two modes. The former is a measure of the amplitude of density fluctuations, and the latter indicates the relative energy in magnetic fluctuations in the component parallel to the background magnetic field Bo. For βe ≪ 1, [C]Alfven ≪ [C]whistler, and the latter quantity is of order 0.5 at whistler propagation strongly oblique to Bo. Such values of C are sometimes measured at relatively high frequencies and βe ≪ 1 in the solar wind; thus, it is concluded that such observations correspond to whistler mode turbulence. But other solar wind observations indicate that kinetic Alfvén fluctuations also contribute to relatively high‐frequency solar wind turbulence.
Equivalent current systems for the annual and semiannual Sq variations observed along the 210°MM CPMN stations
Authors: Yamazaki Y. , Yumoto K. , Uozumi T. , Yoshikawa A. , Cardinal M. G.
Published: December 2009

We analyzed ground magnetometer data for the 10 International Quiet Days during 1996–2007. The data were obtained from 19 stations along 210°magnetic meridian (MM) of the Circum‐pan Pacific Magnetometer Network (CPMN) covering both the Northern Hemisphere and Southern Hemisphere. From the daily variations of the geomagnetic field, we deduced the latitude‐local time (LAT‐LT) diagram of the equivalent Sq current system, which can be regarded as the superposition of the following three current systems: Sq0, Sq1, and Sq2. The Sq0, Sq1, and Sq2 current systems are equivalent current systems for the yearly average, annual variation, and semiannual variation of the Sq field, respectively. We have examined temporal and spatial features of these current systems. The principal features are as follows: (1) The total current intensities of the Sq1 and Sq2 current systems are about 35% and 15% of that of the Sq0 current system, respectively. (2) The Sq0 and Sq2 current systems have a dayside vortex in each hemisphere, while the Sq1 current system has a single vortex centered at the equatorial region in the morning sector (∼1000 LT).
New determinations of 40Ar/39Ar isotopic ages and flow volumes for Cenozoic volcanism in the Terror Rift, Ross Sea, Antarctica
Authors: Rilling S. , Mukasa S. , Wilson T. , Lawver L. , Hall C.
Published: December 2009

This study provides new determinations of 40Ar/39Ar isotopic ages and flow volumes for submarine and subaerial Neogene volcanism developed within the Terror Rift, Ross Sea, Antarctica, the youngest segment of the West Antarctic Rift System. The study is based on the first dredged samples from seven seamounts north of Ross Island, as well as new data from Franklin and Beaufort Islands. The sampled foidite and basanitic lavas range in age from Quaternary (90 ± 66 ka) on a small seamount ∼10 km north of Franklin Island to 6.80 ± 0.05 Ma on Beaufort Island. These ages are consistent with ages of volcanism in both the Melbourne and Erebus Volcanic Provinces and significantly expand the documented area of Neogene magmatism in Victoria Land. There is no geographic progression of volcanism through time, but volcanism was voluminous in the Pliocene and particularly widespread during the Pleistocene. Two of the dredges sampled edifices comprised of less than 0.2 km3 of volcanic materials. The largest seamount in the study area has 58.8 km3 of volcanic material and represents growth over a period of several thousand years. Estimated minimum eruption rates range from 2 × 10−4 km3 y−1 to 2 × 10−3 km3 y−1, consistent with rates proposed for other rift systems and nearby Mt. Erebus. Recent estimates of extension magnitude for the Terror Rift correspond to minimal decompression of only 0.10 to 0.22 GPa and therefore limited melt output of a typical peridotite source.
Geostrophic dynamics of meridional transport variability in the subpolar North Atlantic
Authors: Bingham R. J. , Hughes C. W.
Published: December 2009

The North Atlantic meridional overturning circulation (MOC) is believed to play an important role in regulating the Earth's climate. Yet, there is still much uncertainty regarding the dynamics of the MOC and its variability. It is well established, however, that through geostrophy the zonally integrated meridional transport at a particular latitude and depth can be determined from the east‐west bottom pressure difference across the basin. Therefore, rather than consider the MOC as a large‐scale system, this paper focuses on the dynamics of this geostrophic relationship in two numerical ocean models at a single latitude (50°N) in the subpolar Atlantic. First, it is shown that the bottom pressure on the western boundary is sufficient to recover, with high fidelity, the interannual meridional transport variability at 50°N over a 100 year period in the climate model HadCM3. It is found that the variability of western boundary pressure is closely associated with density changes over the continental slope. These changes lead to a large zonal gradient in potential energy and imply an unfeasible depth‐mean velocity over the slope. The western boundary pressure, from which the meridional transport can be recovered, is generated as a compensation to this and limits the depth‐mean flow. This demonstrates that in numerical ocean models, at least, meridional transport variability is generated as a local response to density changes on the western slope. Whether this is a true representation of actual ocean variability is uncertain, but if it were, then meridional transport variability could largely be determined using only the density field on the western slope.
Evaluation of AIRS, IASI, and OMI ozone profile retrievals in the extratropical tropopause region using in situ aircraft measurements
Authors: Pittman Jasna V. , Pan Laura L. , Wei Jennifer C. , Irion Fredrick W. , Liu Xiong , Maddy Eric S. , Barnet Christopher D. , Chance Kelly , Gao Ru‐Shan
Published: December 2009

We evaluate ozone profile retrievals from the Atmospheric Infrared Sounder (AIRS), the Infrared Atmospheric Sounding Interferometer (IASI), and the Ozone Monitoring Instrument (OMI) using in situ measurements collected on board the NSF/NCAR Gulfstream‐V aircraft during the Stratosphere‐Troposphere Analyses of Regional Transport 2008 (START08) experiment. The focus of this study is to examine how well the satellite retrieval products capture the ozone gradients and variability in the extratropical upper troposphere lower stratosphere (UTLS). The AIRS retrieval examined is version 5, while IASI and OMI retrievals are research products. All satellite instruments show excellent ability in capturing synoptic‐scale ozone gradients associated with strong potential vorticity (PV) gradients. The positive ozone‐PV correlation near the tropopause is also well represented in the satellite data in comparison to collocated aircraft measurements. During aircraft cruise legs, more than 90% of collocated satellite retrievals agree with aircraft measurements within ±50% for ozone mixing ratios greater than 200 ppbv. Below 200 ppbv, AIRS and IASI retrievals show significant positive biases, while OMI shows both positive and negative biases. Ozone gradients across the tropopause are well‐captured, with median values within 30% (positive for AIRS and IASI, negative for OMI) and variances within ±50%. Ozone variability in the UTLS is captured by the satellite retrievals at the 80% level. In the presence of high clouds, however, the infrared retrievals show the largest positive biases. Despite the limited vertical information content, the high horizontal coverage and long‐term data availability make these satellite data sets a valuable asset for UTLS research.
A review of North Atlantic modes of natural variability and their driving mechanisms
Authors: Grossmann Iris , Klotzbach Philip J.
Published: December 2009

This paper reviews three modes of natural variability that have been identified in the North Atlantic Ocean, namely, the North Atlantic Oscillation (NAO), the Atlantic Multidecadal Oscillation (AMO) and the Atlantic Meridional Mode (AMM). This manuscript focuses on the multidecadal fluctuations of these three modes. A range of different mechanisms to initiate phase reversals in these modes on multidecadal timescales has been suggested previously. We propose a systematic grouping of these mechanisms into three types that involve, respectively, (1) the dependency of the Atlantic thermohaline circulation (THC) on salinity, (2) the sensitivity of the THC to changes in ocean heat transport and (3) the dependency of the NAO to changes in the Atlantic meridional temperature gradient. Some new density data is also provided, demonstrating physical links between the THC and the AMO.
Language Performance of Low-Income African American and European American Preschool Children on the PPVT–III
Authors: Qi Cathy Huaqing , Kaiser Ann P. , Milan Stephanie , Hancock Terry
Published: December 2009

Purpose

The performance of low-income African American preschoolers (36 to 52 months old) on the Peabody Picture Vocabulary Test—Third Edition (PPVT–III; L. M. Dunn & L. M. Dunn, 1997) was examined to provide a norm for assessing the performance of this population and to explore the link between socioeconomic status (SES) and language scores on the PPVT–III.

Method

Four hundred and eighty-two African American and 52 European American children in a comparison group were individually administered the PPVT–III.

Results

On average, African American children performed approximately 1.5SDbelow the expected mean based on national norms. Using standard cutoff scores, the PPVT–III identified more children as having language delays than did other measures of language abilities. Socioeconomic factors were related to PPVT–III scores, indicating that the degree of disadvantage within children with low SES was related to language abilities. Maternal education level, marital status, and the number of children in the household were uniquely associated with children’s performance on the PPVT–III.

Clinical Implications

The importance of supporting language development in preschool children from low-income families is discussed.
Performance on the PPVT–III and the EVT: Applicability of the Measures With African American and European American Preschool Children
Authors: Restrepo María Adelaida , Schwanenflugel Paula J. , Blake Jamilia , Neuharth-Pritchett Stacey , Cramer Stephen E. , Ruston Hilary P.
Published: December 2009

Purpose

The purpose of this study was to determine whether two vocabulary measures were appropriate for the evaluation of African American children and children whose mothers have low education levels, regardless of gender.

Method

Data were collected for 210 high-risk, preschool children from a southeastern state in the United States on the Peabody Picture Vocabulary Test—Third Edition (PPVT–III; L. M. Dunn & L.M. Dunn, 1997) and the Expressive Vocabulary Test (EVT; K. T. Williams, 1997).

Results

Results indicated that African American children and children whose mothers had low education levels tended to score lower on both measures than did children from European American backgrounds and children whose mothers had a high school or higher education; however, this effect was larger for the PPVT–III.

Clinical Implications

Data suggest that the EVT is a better indicator of a child’s “vocabulary” skill, and that the PPVT–III has a greater tendency than the EVT to place African American children and children whose mothers have low education levels at risk for being unfairly identified as presenting with a potential language disorder. These data indicate that practitioners should use alternative assessment methods such as nonstandard and dynamic assessments to test children’s vocabulary skill. In particular, if they use the PPVT–III, practitioners should take great caution in interpreting test results as evidence of a vocabulary problem in African American children and children whose mothers have low education levels.
English Language Narratives of Filipino Children
Authors: Lofranco Lee Ann L. , Peña Elizabeth D. , Bedore Lisa M.
Published: December 2009

Purpose

The current study focuses on describing the English language narrative skills of children who have been exposed to the Filipino language.

Method

Eight children between the ages of 6;0 (years;months) and 7;7 who spoke primarily English but who were exposed to the Filipino language at home participated. Each child produced three narrative samples based on wordless picture books. Samples were analyzed for narrative complexity as well as measures of productivity and grammaticality.

Results

The complexity of children’s narratives was comparable to that reported in the literature for monolingual English-speaking children. Grammaticality measures show use of an average of 16.55% Filipino-influenced English forms across three stories. The observed patterns of Filipino-influenced English were predictable based on the comparison of English and Filipino structures. Variability in maze use was related to the amount of exposure to Filipino.

Clinical Implications

Care should be taken to evaluate grammaticality with respect to nonstandard English forms predicted by the rules of the language in contact with English. Further, maze use may be related to level of exposure to another language and should be further explored when using such information in language evaluation.
Eligibility Criteria for Language Impairment
Authors: Spaulding Tammie J. , Plante Elena , Farinella Kimberly A.
Published: December 2009

Purpose

The assumption that children with language impairment will receive low scores on standardized tests, and therefore that low scores will accurately identify these children, is examined through a review of data in the manuals of tests that are intended for use in identifying such children.

Method

Data from 43 commercially available tests of child language were compiled to identify whether evidence exists to support their use in identifying language impairment in children.

Results

A review of data concerning the performance of children with impaired language failed to support the assumption that these children will routinely score at the low end of a test’s normative distribution. A majority of tests reported that such children scored above 1.5
SD
below the mean, and scores were within 1
SD
of the mean for more than a quarter (27%) of the tests. The primary evidence needed to support the purpose of identification, test sensitivity and specificity, was available for 9 of the 43 tests, and acceptable accuracy (80% or better) was reported for 5 of these tests.

Implications

Specific data supporting the application of “low score” criteria for the identification of language impairment is not supported by the majority of current commercially available tests. However, alternate sources of data (sensitivity and specificity rates) that support accurate identification are available for a subset of the available tests.
Survey of SLP Caseloads in Washington State Schools: Implications and Strategies for Action
Authors: Dowden Patricia , Alarcon Nancy , Vollan Teresa , Cumley Gary D. , Kuehn Carrie M. , Amtmann Dagmar
Published: December 2009

Purpose

To document statewide and regional caseloads and to examine workload management strategies by surveying speech-language pathologists (SLPs) in Washington State public schools.

Method

All school SLPs who were registered with the Office of the Superintendent of Public Instruction were mailed a detailed survey in May, 2001 and a brief follow-up survey 1 year later.

Results

Response rates were 43% (
N
= 431) and 47% (
N
= 464), respectively. Caseload findings showed a statewide mean of 59 students, with regional variation as high as 30%.

Implications

There was no systematic evidence that caseloads were managed through state, district, or local limits or by distributing clients on the basis of the severity of impairment or SLP experience or training. There was significant evidence, however, that clinicians with larger caseloads were more likely to have assistants and to conduct a higher proportion of group sessions than were clinicians with smaller caseloads. The authors discuss the implication of these findings for this and other states with no caseload limits and a shortage of SLPs. There is an appeal for more research using newly established measures of workload as well as a call to action to address the challenges that these findings represent.
Comparing Monotic and Diotic Selective Auditory Attention Abilities in Children
Authors: Cherry Rochelle , Rubinstein Adrienne
Published: December 2009

Purpose

Some researchers have assessed ear-specific performance of auditory processing ability using speech recognition tasks with normative data based on diotic administration. The present study investigated whether monotic and diotic administrations yield similar results using the Selective Auditory Attention Test.

Method

Seventy-two typically achieving children were tested both monotically and diotically in a counterbalanced, repeated measures design.

Results

Results revealed that diotic scores were significantly higher than monotic scores, with no significant difference between right and left ears.

Conclusion

Collecting ear-specific normative data is recommended over extrapolating from norms using a diotic speech recognition test. Because a binaural advantage may be found when listening under challenging conditions, the strategy of occluding one ear in children with (central) auditory processing disorder ([C]APD) should be reconsidered.
Nonword Repetition and Sentence Repetition as Clinical Markers of Specific Language Impairment: The Case of Cantonese
Authors: Stokes Stephanie F. , Wong Anita M-Y. , Fletcher Paul , Leonard Laurence B.
Published: December 2009

Purpose

Recent research suggests that nonword repetition (NWR) and sentence repetition (SR) tasks can be used to discriminate between children with SLI and their typically developing age-matched (TDAM) and younger (TDY) peers.

Method

Fourteen Cantonese-speaking children with SLI and 30 of their TDAM and TDY peers were compared on NWR and SR tasks. NWR of IN nonwords (CV combinations attested in the language) and OUT nonwords (CV combinations unattested in the language) were compared. SR performance was compared using 4 different scoring methods.

Results

The SLI group did not score significantly lower than the TDAM group on the test of NWR (overall results were TDAM = SLI > TDY). There were nonsignificant group differences on IN syllables but not on OUT syllables. The results do not suggest a limitation in phonological working memory in Cantonese-speaking children with SLI. The SR task discriminated between children and their TDAM peers but not between children with SLI and their TDY peers matched for mean length of utterance.

Conclusions

SR but not NWR discriminates between children with SLI and their TDAM peers. Poorer NWR for English-speaking children with SLI might be attributable to weaker use of the redintegration strategy in word repetition. Further cross-linguistic investigations of processing strategies are required.
Can Severely Language Delayed 3-Year-Olds Be Identified at 18 Months? Evaluation of a Screening Version of the MacArthur–Bates Communicative Development Inventories
Authors: Westerlund Monica , Berglund Eva , Eriksson Mårten
Published: December 2009

Purpose

To evaluate the effectiveness of a screening instrument (the Swedish Communication Screening at 18 months of age; SCS18), derived from the Swedish MacArthur–Bates Communicative Development Inventory, in identification of 18-month-old children who will be severely language disabled by 3 years of age, the authors (a) analyzed which SCS18’s component yielded the best prediction, (b) compared the productivity figures of the SCS18 with those of the traditional method of identification, and (c) tried different cutoff criteria of the SCS18.

Method

Half of the child health care (CHC) centers in a Swedish county were randomly selected to use the SCS18 (e.g., a checklist supporting parents in assessing their child’s word production, word comprehension, and communicative gestures). Remaining CHC centers used an informal assessment. Expressive and receptive language was subsequently judged with an observation for 3-year-olds that is routine in the county. An unselected population of 2,080 children participated at 18 months of age and again at 3 years of age.

Result

Number of spoken words yielded the best prediction, and SCS18 was superior to the traditional method. A sensitivity of 50%, however, was not enough, and a stricter criterion resulted in too many false positives to be acceptable as routine.

Conclusion

Although the SCS18 has strength, the age of 18 months seems to be too early for identification of severe language disability.
The Impact of Augmentative and Alternative Communication Intervention on the Speech Production of Individuals With Developmental Disabilities: A Research Review
Authors: Millar Diane C. , Light Janice C. , Schlosser Ralf W.
Published: December 2009

Purpose

This article presents the results of a meta-analysis to determine the effect of augmentative and alternative communication (AAC) on the speech production of individuals with developmental disabilities.

Method

A comprehensive search of the literature published between 1975 and 2003, which included data on speech production before, during, and after AAC intervention, was conducted using a combination of electronic and hand searches.

Results

The review identified 23 studies, involving 67 individuals. Seventeen of these studies did not establish experimental control, thereby limiting the certainty of evidence about speech outcomes. The remaining 6 studies, involving 27 cases, had sufficient methodological rigor for the “best evidence analysis” (cf. R. E. Slavin, 1986). Most of the participants (aged 2–60 years) had mental retardation or autism; the AAC interventions involved instruction in manual signs or nonelectronic aided systems. None of the 27 cases demonstrated decreases in speech production as a result of AAC intervention, 11% showed no change, and the majority (89%) demonstrated gains in speech. For the most part, the gains observed were modest, but these data may underestimate the effect of AAC intervention on speech production because there were ceiling effects.

Conclusions

Future research is needed to better delineate the relationship between AAC intervention and speech production across a wider range of participants and AAC interventions.
Visuospatial Immediate Memory in Specific Language Impairment
Authors: Archibald Lisa M. D. , Gathercole Susan E.
Published: December 2009

Purpose

Investigations of the cognitive processes underlying specific language impairment (SLI) have implicated deficits in verbal short-term and working memory and in particular the storage and processing of phonological information. This study investigated short-term and working memory for visuospatial material for a group of children with SLI, to test whether the verbal memory impairments already established extend to the visuospatial domain.

Method

Fifteen children with SLI and control groups of children matched on chronological age and language age completed tests of visuospatial short-term and working memory.

Results

The SLI group performed comparably with age-matched control children on all measures and at a higher level than the language-age control group on several measures.

Conclusions

The visuospatial short-term and working memory abilities were at age-appropriate levels in this SLI group. This contrasts markedly with their impairments on tests of verbal short-term and working memory.
Language Deficits in Poor Comprehenders: A Case for the Simple View of Reading
Authors: Catts Hugh W. , Adlof Suzanne M. , Weismer Susan Ellis
Published: December 2009

Purpose

To examine concurrently and retrospectively the language abilities of children with specific reading comprehension deficits (“poor comprehenders”) and compare them to typical readers and children with specific decoding deficits (“poor decoders”).

Method

In Study 1, the authors identified 57 poor comprehenders, 27 poor decoders, and 98 typical readers on the basis of 8th-grade reading achievement. These subgroups' performances on 8th-grade measures of language comprehension and phonological processing were investigated. In Study 2, the authors examined retrospectively subgroups' performances on measures of language comprehension and phonological processing in kindergarten, 2nd, and 4th grades. Word recognition and reading comprehension in 2nd and 4th grades were also considered.

Results

Study 1 showed that poor comprehenders had concurrent deficits in language comprehension but normal abilities in phonological processing. Poor decoders were characterized by the opposite pattern of language abilities. Study 2 results showed that subgroups had language (and word recognition) profiles in the earlier grades that were consistent with those observed in 8th grade. Subgroup differences in reading comprehension were inconsistent across grades but reflective of the changes in the components of reading comprehension over time.

Conclusions

The results support the simple view of reading and the phonological deficit hypothesis. Furthermore, the findings indicate that a classification system that is based on the simple view has advantages over standard systems that focus only on word recognition and/or reading comprehension.
Speech Perception for Adults Who Use Hearing Aids in Conjunction With Cochlear Implants in Opposite Ears
Authors: Mok Mansze , Grayden David , Dowell Richard C. , Lawrence David
Published: December 2009

This study aimed to (a) investigate the effect of using a hearing aid in conjunction with a cochlear implant in opposite ears on speech perception in quiet and in noise, (b) identify the speech information obtained from a hearing aid that is additive to the information obtained from a cochlear implant, and (c) explore the relationship between aided thresholds in the nonimplanted ear and speech perception benefit from wearing a hearing aid in conjunction with a cochlear implant in opposite ears.

Fourteen adults who used the Nucleus 24 cochlear implant system in 1 ear participated in the study. All participants had either used a hearing aid in the nonimplanted ear for at least 75% of waking hours after cochlear implantation, and/or, hearing loss less than 90 dB HL in the low frequencies in the nonimplanted ear. Speech perception was evaluated in 3 conditions: cochlear implant alone (CI), hearing aid alone (HA), and cochlear implant in conjunction with hearing aid in opposite ears (CIHA). Three speech perception tests were used: consonant–vowel nucleus–consonant (CNC) words in quiet, City University of New York style (CUNY) sentences in coincident signal and noise, and spondees in coincidental and spatially separated signal and noise. Information transmission analyses were performed on the CNC responses.

Of the 14 participants tested, 6 showed significant bimodal benefit on open-set speech perception measures and 5 showed benefit on close-set spondees. However, 2 participants showed poorer speech perception with CIHA than CI in at least 1 of the speech perception tests. Results of information transmission analyses showed that bimodal benefit (performance with CIHA minus that with CI) in quiet arises from improved perception of the low frequency components in speech. Results showed that participants with poorer aided thresholds in the mid-to-high frequencies demonstrated greater bimodal benefit. It is possible that the mid-to-high frequency information provided by the hearing aids may be conflicting with the cochlear implants.
Development of Auditory Saltation and Its Relationship to Reading and Phonological Processing
Authors: Kidd Joanna C. , Hogben John H.
Published: December 2009

Purpose

The temporal offset of auditory saltation is thought to be reflective of the limits of temporal resolution, and has recently been used to compare dyslexic and control adults and children, with mixed results (R. Hari & P. Kiesilä, 1996; M. Kronbichler, F. Hutzler, & H. Wimmer, 2002). This study sought to document and understand normative changes in saltation thresholds as a function of age, and examine the relationship of saltation thresholds to reading and phonological processing across development.

Method

This study used a cross-sectional developmental design. Groups of 7–8-, 9–10-, and 11–13-year-old children, and adults, undertook a 2-alternative forced-choice saltation task, along with standard tests of reading and phonological processing.

Results

Significantly higher and more variable saltation thresholds were evident in the 7–8-year-old group. Group distributions were skewed: Only a few young children obtained poor thresholds while most showed adult-like performance. Saltation thresholds were not related to reading or phonological processing skills at any stage of development.

Conclusions

The temporal offset of saltation is unlikely to reflect the true limits of temporal resolution in young children, but rather the conflation of perceptual and nonperceptual factors (such as poor short-term memory, inattention, and confusion) to task performance. Effort should be made to minimize such nonperceptual factors, particularly when using saltation as a measure of temporal resolution in participants with dyslexia.
Speech Perception in Individuals With Auditory Neuropathy
Authors: Zeng Fan-Gang , Liu Sheng
Published: December 2009

Purpose

Speech perception in participants with auditory neuropathy (AN) was systematically studied to answer the following 2 questions: Does noise present a particular problem for people with AN? Can clear speech and cochlear implants alleviate this problem?

Method

The researchers evaluated the advantage in intelligibility of clear speech over conversational speech in 13 participants with AN. Of these participants, 7 had received a cochlear implant. Eight sentence-recognition experiments were conducted to examine the clear speech advantage in 2 listening conditions (quiet and noise) using 4 stimulation modes (monaural acoustic, diotic acoustic, monaural electric, and binaurally combined acoustic and electric stimulation).

Results

Participants with AN performed more poorly in speech recognition in noise than did the normal-hearing, cochlear-impaired, and cochlear implant controls. A significant clear speech advantage was observed, ranging from 9 to 23 percentage points in intelligibility for all listening conditions and stimulation modes. Electric stimulation via a cochlear implant produced significantly higher intelligibility than acoustic stimulation in both quiet and in noise. Binaural hearing with either diotic acoustic stimulation or combined acoustic and electric stimulation produced significantly higher intelligibility than monaural stimulation in quiet but not in noise.

Conclusions

Participants with AN most likely derive the clear speech advantage from enhanced temporal properties in clear speech and improved neural synchrony with electric stimulation. Although the present result supports cochlear implantation as one treatment choice for people with AN, it suggests that the use of innovative hearing aids may be another viable option to improve speech perception in noise.
Parametric Quantitative Acoustic Analysis of Conversation Produced by Speakers With Dysarthria and Healthy Speakers
Authors: Rosen Kristin M. , Kent Raymond D. , Delaney Amy L. , Duffy Joseph R.
Published: December 2009

Purpose

This study’s main purpose was to (a) identify acoustic signatures of hypokinetic dysarthria (HKD) that are robust to phonetic variation in conversational speech and (b) determine specific characteristics of the variability associated with HKD.

Method

Twenty healthy control (HC) participants and 20 participants with HKD associated with idiopathic Parkinson’s disease (PD) repeated 3 isolated sentences (controlled phonetic content) and 2 min of conversational speech (phonetic content treated as a random variable). A MATLAB-based program automatically calculated measures of contrastivity: speech–pause ratio, intensity variation, median and maximum formant slope, formant range, change in the upper and lower spectral envelope, and range of the spectral envelope.ttests were used to identify which measures were sensitive to HKD and which measures differed by task. Discriminant analysis was used to identify the combination of measures that best predicted HKD, and this analysis was then used as a general measure of contrastivity (Contrastivity Index). Differential effects of HKD on maximum and typical contrastivity levels were tested with interaction of maximum, minimum, and median observations of individual speakers and with pairwise comparisons of skewness and kurtosis of the contrastivity index distributions.

Results

Group differences were detected with pairwise comparisons withttests in 8 of the 9 measures. Percentage pause time and spectral range were identified as the most specific (95%) and accurate (95%) differentiators of HKD and HC conversational speech. Sentence repetition elicited significantly higher levels of contrastivity than conversational speech in both HC and HKD speakers. Maximum and minimum contrastivities were significantly lower in HKD speech, but there was no evidence that HKD affects maximum contrastivity levels more than median contrastivity levels. The HKD speakers' contrastivity distributions were significantly more skewed to lower levels of production.

Conclusion

HKD can be consistently distinguished from HC speech in both sentence repetition and conversational speech on the basis of intensity variation and spectral range. Although speakers with HKD were effectively able to produce higher contrastivity levels in sentence repetition tasks, they habitually performed closer to the lower end of their production ranges.
Effect of Facemask Use on Respiratory Patterns of Women in Speech and Singing
Authors: Collyer Sally , Davis Pamela J.
Published: December 2009

Purpose

Research into respiratory behavior during singing and speech makes extensive use of standard respiratory and vented pneumotachograph facemasks. This study investigated whether the use of such facemasks would affect respiratory behavior in terms of lung volume (excursion, at initiation and at termination) or duration (of inspiration and of expiration) during speech or singing.

Method

The respiratory patterns of 6 females were recorded using uniaxial surface magnetometry during 4 tasks: quiet breathing, a /pa/ syllabic train, reading (“The Rainbow Passage”), and singing a Christmas carol (“Silent night”). Each task was performed in 4 facemask conditions: wearing no facemask, wearing a facemask rim only, wearing a standard respiratory facemask, and wearing a vented pneumotachograph facemask.

Results

No significant effect was found for any of the facemask conditions on lung volume or duration measures during any tasks.

Conclusion

The results confirm earlier studies that the vented pneumotachograph facemask does not affect breathing behavior in speech research studies and extends the finding to the study of breathing behavior in singing and to the use of a standard respiratory facemask.
Analysis of High-Frequency Electroencephalographic-Electromyographic Coherence Elicited by Speech and Oral Nonspeech Tasks in Parkinson’s Disease
Authors: Caviness John N. , Liss Julie M. , Adler Charles , Evidente Virgilio
Published: December 2009

Purpose

Corticomuscular electroencephalographic-electromyographic (EEG-EMG) coherence elicited by speech and nonspeech oromotor tasks in healthy participants and those with Parkinson’s disease (PD) was examined. Hypotheses were the following: (a) corticomuscular coherence is demonstrable between orbicularis oris (OO) muscles' EMG and scalp EEG recording; (b) the presence, location, and magnitude of coherence is task specific; (c) differences in corticomuscular coherence patterns exist between healthy and PD participants; and (d) differences will manifest as either increased or decreased coherence values in certain frequency bands, with EEG localization at primary sensorimotor cortex and/or supplementary motor area (SMA).

Method

Simultaneous EEG, EMG (OO), and speech samples were recorded on 20 healthy and 20 PD participants during speech and nonspeech tasks. Fast Fourier transform and coherence analysis was performed with Neuroscan software on 1,000 randomly generated epochs per task per group. Corticomuscular coherence was analyzed between each EEG electrode and right and left superior and inferior OO muscles up to 200 Hz. Significant coherence peaks exceeded 95% confidence limits (.003).

Results

Corticomuscular coherence existed for both groups and for all tasks, but to varying degrees in primary sensorimotor cortex and SMA.

Conclusions

Results support task specificity for both groups and, in PD, a diminished modulation flexibility linked to the sensorimotor area and reduced corticomuscular coherence at the SMA.
Theoretical Analysis of Maximum Flow Declination Rate Versus Maximum Area Declination Rate in Phonation
Authors: Titze Ingo R.
Published: December 2009

Purpose

Maximum flow declination rate (MFDR) in the glottis is known to correlate strongly with vocal intensity in voicing. This declination, or negative slope on the glottal airflow waveform, is in part attributable to the maximum area declination rate (MADR) and in part to the overall inertia of the air column of the vocal tract (lungs to lips). The purpose of this theoretical study was to show the possible contributions of air inertance and MADR to MFDR.

Method

A simplified computational model of the kinematics of vocal fold movement was utilized to compute a glottal area function. The glottal flow was computed interactively with lumped vocal tract parameters in the form of resistance and inertive reactance.

Results

It was shown that MADR depends almost entirely on the ratio of vibrational amplitudes of the lower to upper margins of the vocal fold tissue. Adduction, vertical phase difference, and prephonatory convergence of the glottis have a lesser effect on MADR. A relatively simple rule was developed that relates MFDR to a vibrational amplitude ratio and vocal tract inertance.

Conclusion

It was concluded that speakers and singers have multiple options for control of intensity, some of which involve more source–filter interaction than others.
Voice Training and Therapy With a Semi-Occluded Vocal Tract: Rationale and Scientific Underpinnings
Authors: Titze Ingo R.
Published: December 2009

Purpose

Voice therapy with a semi-occluded vocal tract has a long history. The use of lip trills, tongue trills, bilabial fricatives, humming, and phonation into tubes or straws has been hailed by clinicians, singing teachers, and voice coaches as efficacious for training and rehabilitation. Little has been done, however, to provide the scientific underpinnings. The purpose of the study was to investigate the underlying physical principles behind the training and therapy approaches that use semi-occluded vocal tract shapes.

Method

Computer simulation, with a self-oscillating vocal fold model and a 44 section vocal tract, was used to elucidate source–filter interactions for lip and epilarynx tube semi-occlusions.

Results

A semi-occlusion in the front of the vocal tract (at the lips) heightens source–tract interaction by raising the mean supraglottal and intraglottal pressures. Impedance matching by vocal fold adduction and epilarynx tube narrowing can then make the voice more efficient and more economic (in terms of tissue collision).

Conclusion

The efficacious effects of a lip semi-occlusion can also be realized for nonoccluded vocal tracts by a combination of vocal fold adduction and epilarynx tube adjustments. It is reasoned that therapy approaches are designed to match the glottal impedance to the input impedance of the vocal tract.
A new dynamic device for low-dimensional materials testing
Authors: Hua Tao , Xie Huimin , Feng Xue , Wang Xiang , Zhang Jianmin , Chen Pengwan , Zhang Qingming
Published: December 2009

As the geometrical size of low-dimensional materials decreases to micro- or nanoscale, the traditional dynamic loading system cannot be used anymore to measure the dynamic mechanical property. In this study, a new dynamic loading system was developed. A piezoelectric transducer actuator was used for displacement loading, and a mechanical lever was designed to amplify the displacement load. Finite element method simulation and validation experiments were conducted to analyze the strength and function of the mechanical lever. As an application test, a sample from an aluminum film was investigated using the system. The success of the experiment, as shown by the results, demonstrated the feasibility of the system for low-dimensional materials study.
Stabilization of fluorophore in DNA thin films
Authors: Ner Yogesh , Navarathne Daminda , Niedzwiedzki Dariusz M. , Grote James G. , Dobrynin Andrey V. , Frank Harry A. , Sotzing Gregory A.
Published: December 2009

The photostability of the nonlinear optical dye, Hemi-22, improves upon encapsulation in DNA thin films. The interactions of Hemi-22 with DNA, along with the intrinsic properties of DNA are responsible for these remarkable improvements in the photostability of the dye in comparison to the dye in a poly(methyl methacrylate) as a control.
Critical points bifurcation analysis of high-ℓ bending dynamics in acetylene
Authors: Tyng Vivian , Kellman Michael E.
Published: December 2009

The bending dynamics of acetylene with pure vibrational angular momentum excitation and quantum number ℓ≠0 are analyzed through the method of critical points analysis, used previously [V. Tyng and M. E. Kellman, J. Phys. Chem. B 110, 18859 (2006)] for ℓ=0 to find new anharmonic modes born in bifurcations of the low-energy normal modes. Critical points in the reduced phase space are computed for continuously varied bend polyad number Nb=n4+n5 as ℓ=ℓ4+ℓ5 is varied between 0 and 20. It is found that the local L, orthogonal O, precessional P, and counter-rotator CR families persist for all ℓ. In addition, for ℓ≥8, there is a fifth family of critical points which, unlike the previous families, has no fixed relative phase (“off great circle” OGC). The concept of the minimum energy path in the polyad space is developed. With restriction to ℓ=0 this is the local mode family L. This has an intuitive relation to the minimum energy path or reaction mode for acetylene-vinylidene isomerization. With ℓ≥0 included as a polyad number, the ℓ=0 minimum energy path forms a troughlike channel in the minimum energy surface in the polyad space, which consists of a complex mosaic of L, O, and OGC critical points. There is a division of the complete set of critical points into layers, the minimum energy surface forming the lowest.
The Aharonov–Bohm effect and Tonomura et al. experiments: Rigorous results
Authors: Ballesteros Miguel , Weder Ricardo
Published: December 2009

The Aharonov–Bohm effect is a fundamental issue in physics. It describes the physically important electromagnetic quantities in quantum mechanics. Its experimental verification constitutes a test of the theory of quantum mechanics itself. The remarkable experiments of Tonomura et al. [“Observation of Aharonov-Bohm effect by electron holography,” Phys. Rev. Lett 48, 1443 (1982) and “Evidence for Aharonov-Bohm effect with magnetic field completely shielded from electron wave,” Phys. Rev. Lett 56, 792 (1986)] are widely considered as the only experimental evidence of the physical existence of the Aharonov–Bohm effect. Here we give the first rigorous proof that the classical ansatz of Aharonov and Bohm of 1959 [“Significance of electromagnetic potentials in the quantum theory,” Phys. Rev. 115, 485 (1959)], that was tested by Tonomura et al., is a good approximation to the exact solution to the Schrödinger equation. This also proves that the electron, that is, represented by the exact solution, is not accelerated, in agreement with the recent experiment of Caprez et al. in 2007 [“Macroscopic test of the Aharonov–Bohm effect,” Phys. Rev. Lett. 99, 210401 (2007)], that shows that the results of the Tonomura et al. experiments can not be explained by the action of a force. Under the assumption that the incoming free electron is a Gaussian wave packet, we estimate the exact solution to the Schrödinger equation for all times. We provide a rigorous, quantitative error bound for the difference in norm between the exact solution and the Aharonov–Bohm Ansatz. Our bound is uniform in time. We also prove that on the Gaussian asymptotic state the scattering operator is given by a constant phase shift, up to a quantitative error bound that we provide. Our results show that for intermediate size electron wave packets, smaller than the ones used in the Tonomura et al. experiments, quantum mechanics predicts the results observed by Tonomura et al. with an error bound smaller than 10−99. It would be quite interesting to perform experiments with electron wave packets of intermediate size. Furthermore, we provide a physical interpretation of our error bound.