bluuebunny/crossref_metadata_2025 huggingface dataset:
Expression of DNA repair gene Ku80 in lymphoid neoplasm
Authors: Chen Tsai‐Yun , Chen Jiann‐Shiuh , Su Wu‐Chou , Wu Ming‐Shiuan , Tsao Chao‐Jung
Published: May 2005

Abstract:  Objectives: Ku, a heterodimer of KU70 and Ku80 that binds to double‐strand DNA breaks (DSBs) and activates the catalytic subunit (DNA‐PKcs) when DNA is bound, is essential in DSB repair and V(D)J recombination. Ku80 is a putative tumor suppressor gene that might play an important role in drug resistance. Our aim was to determine the role of Ku80 in lymphoid malignancy. Patients and methods: Competitive reverse transcription‐polymerase chain reaction assays were performed and the expression levels of Ku80 were measured in normal peripheral blood mononuclear cells (n = 9) and malignant cells from 25 patients with acute lymphoblastic leukemia (ALL) (14 children, 11 adults), and chronic lymphoproliferative disorders (n = 6). The Ku80 transcripts were sequencing for the possibility of mutation. Results: No mutation or Ku80 variant at the RNA level was seen in any patient samples or in the Raji or CCRF‐CEM cell lines. In Ku80 expression, 8.8‐, 1.9‐, and 6.2‐fold mean increases were seen in adult, pediatric ALL, and chronic lymphoid malignancies compared with the control. The Ku80 was significantly higher in adult than in pediatric ALL (P = 0.02). The amount of Ku80 expression in ALL was moderately correlated with peripheral white blood cell counts, but not with Ki67 labeling index. High Ku80 expressers (higher than the mean of all patients with ALL) tended to respond poorly to therapy: Only 22% of high Ku80 expressers achieved durable complete remission compared to 62% of low expressers. Conclusions: Our study suggests that Ku80 might contribute to generally poor prognoses in adult ALL.
Microarray‐based classification of diffuse large B‐cell lymphoma
Authors: Poulsen Christian Bjørn , Borup Rehannah , Nielsen Finn Cilius , Borregaard Niels , Hansen Mads , Grønbæk Kirsten , Møller Michael Boe , Ralfkiaer Elisabeth
Published: May 2005

Abstract:  Objective: Hierarchical clusterings of diffuse large B‐cell lymphoma (DLBCL) based on gene expression signatures have previously been used to classify DLBCL into Germinal Center B‐cell (GCB) and Activated B‐cell (ABC) types. To examine if it was feasible to perform a cross‐platform validation on the Affymetrix HG‐U133A oligonucleotide arrays and improve the classification, we determined the expression profiles of pretreatment, diagnostic samples from 52 primary nodal DLBCL. Methods and results: First, three previously published gene lists were converted to the HG‐U133A probe sets and used for hierarchical clustering. In this way, three subtypes, including the GCB type (n = 20), the ABC type (n = 25) and an intermediate group, Type‐3 (n = 5), were distinguished. The CD10 and Bcl‐6 expression as well as t(14;18) translocation were prevalent, but not exclusive to the GCB type. By contrast, MUM1 was only expressed in the ABC and in Type‐3 samples. The 5‐year survival was similar between the groups, but GCB patients showed a better initial response to CHOP or CHOP‐like regimens than the remaining patients and tended to have less advanced disease and lower IPI scores. As a next step, an improved set of classifier genes was generated by analysis of 34 patients that were consistently classified as GCB or ABC in the above analyses. Seventy‐eight genes were selected and demonstrated on two previously published data sets (Shipp et al. Nat Med 2002;8:68–74 and Houldsworth et al. Blood 2004;103:1862–1868) to exhibit a higher specificity than the original gene lists. Conclusion: We conclude that gene expression profiling with Affymetrix Genechips is efficient to distinguish between GCB and ABC types of DLBCL and that these are likely to represent separate biological entities. The Genechip platform is highly standardised and therefore useful for future prospective investigations to establish the value of gene expression profiling in the clinical management of DLBCL.
On the spectral presence of the predecessor in James Joyce – With special reference to William Shakespeare
Authors: Boysen Benjamin
Published: May 2005

The work of James Joyce is haunted by the question of the predecessor, who is simultaneously perceived as the generous source or progenitor, the beginning of being, the imago of the present living ego, and as the threatening rival. As the predecessor of Joyce par excellence, Shakespeare, in the works of the Irish author, confirms in a most significant and rich way how the relation to this oddly absent presence is marked by a fundamental ambivalence. The living are nourished by the gift of the no longer existing; they are paradoxically given existence by those who have none, which is why these ghosts are perceived in an ambivalent manner. The predecessor is the heritage of the living poet, and this heritage is always the poet's other, without which he would be deprived of artistic being, but which nevertheless threatens to deprive him of independence, autonomy, originality and being. This conflict with the ghost for being and autonomy, takes place between Joyce and Shakespeare throughout the pages of Ulysses and Finnegans Wake, where the latter continues to awake the jealousy, agony and rivalry of the former. The predecessor's position remains, above all, ambivalent, and nowhere else is this phenomena explored, analyzed, and demonstrated as thorough and as insistently as in the work of Joyce.
Identitätsproblematik und Gesellschaftskritik. Zum Solferino‐Kapitel in Joseph Roths Radetzkymarsch
Authors: Schlosser Jan T
Published: May 2005

Der Beitrag versucht die Funktion des Eingangskapitels im Radetzkymarsch zu bestimmen. Mit diesem Kapitel hat Roth ein gesellschaftskritisches Gegengewicht zum apologetischen Gesamtgefüge des Romans etabliert. Der habsburgkritische Wert des Solferino‐Kapitels entfaltet sich vor dem Hintergrund der Entwicklung einer an der Figur des alten Trotta ablesbaren gesellschaftlich bedingten Identitätsproblematik. Die systemimmanenten Schwächen und Konflikte der Monarchie spiegeln sich im Bewußtsein des ‘Helden von Solferino’, verunstalten seinen Charakter, lassen ihn zu einem Lebensschwachen mutieren und werden bezeichnenderweise ‐ bis zur späteren Implosion des Vielvölkerstaates ‐ nicht auf einer politischen Ebene ausgetragen. Demzufolge ist die Identitätssuche auf einen privaten Raum ausgerichtet, der aber gleichfalls keine permanente Identität zu garantieren vermag.
Comparison of Methodologies for Determination of Fracture Strength of 8mol% Yttria-Stabilized Zirconia Electrolyte Materials
Authors: An Ke , Halverson Howard G. , Reifsnider Kenneth L. , Case Scott W. , McCord Marshall H.
Published: May 2005

The widely used yttria-stabilized zirconia (YSZ) electrolyte is subjected to thermal and external stresses under operation, so that the enhancement of the mechanical properties is an important issue in planar solid oxide fuel cells. Fracture strengths of 8mol% YSZ electrolytes as 100×100mm squire plates, 23mm disks, and 17mm disks were evaluated using plate tensile, ball-on-ring, and pressure-on-ring testing methodologies, respectively. Finite element analysis (FEA) was validated and used to calculate the stress distribution and peak stress for the biaxial strength tests. A Weibull analysis was carried out on the test∕FEA-predicted peak stresses, and Weibull strength, modulus, and material scale parameters were found for each test methodology. The methodologies were compared and evaluated based on the results of the Weibull analysis; the pressure-on-ring test is preferred for brittle thin-film fracture strength testing.
Discharge of a Segmented Polymer Electrolyte Membrane Fuel Cell
Authors: Berg P. , Promislow K. , Stumper J. , Wetton B.
Published: May 2005

We present a transient model for an electrically segmented polymer electrolyte membrane (PEM) fuel cell which is run until extinction from a finite oxygen supply. The experimental cell is divided into 16 electrically isolated pucks which are fed oxygen from a small reserve and hydrogen from a conventional flow field. The experimental voltage and through-plane current in each puck, and puck-to-puck currents are recorded and compared to computed profiles. Seven qualitative characteristics of the current profiles during discharge are identified. These are used as targets for parameter tuning, from which puck-to-puck water distribution within the membrane electrode assembly (MEA) is inferred. The model is sensitive to system parameters, and holds promise as an in situ diagnostic tool for tracking this distribution by using MEA oxygen transport characteristics.
Optimization of the Operating Parameters of a Proton Exchange Membrane Fuel Cell for Maximum Power Density
Authors: Mawardi A. , Yang F. , Pitchumani R.
Published: May 2005

The performance of fuel cells can be significantly improved by using optimum operating conditions that maximize the power density subject to constraints. Despite its significance, relatively scant work is reported in the open literature on the model-assisted optimization of fuel cells. In this paper, a methodology for model-based optimization is presented by considering a one-dimensional nonisothermal description of a fuel cell operating on reformate feed. The numerical model is coupled with a continuous search simulated annealing optimization scheme to determine the optimum solutions for selected process constraints. Optimization results are presented over a range of fuel cell design parameters to assess the effects of membrane thickness, electrode thickness, constraint values, and CO concentration on the optimum operating conditions.
Noninvasive reflection spectra provide quantitative information about the spatial distribution of skin chromophores
Authors: Niedorf F. , Jungmann H. , Kietzmann M.
Published: May 2005

In this work, a new method of analyzing noninvasive reflection spectra is presented. The approach explicitly models the inhomogeneity of chromophore distributions in living tissues and thus extracts not only apparent chromophore concentrations but also relative chromophore distributions in tissues. Furthermore, it works with spectra obtained with short source‐detector separations where the diffusion theory of light transport through turbid media is not valid, and formerly presented methods thus fail. The effect of inhomogeneously distributed chromophores in a multicompartment model of tissues on measured reflection spectra is explained and an algorithm to deconvolute tissue spectra based on this model is presented. It is evaluated using simulated spectra and measurements on phantoms, which are made up of partially printed pieces of paper to simulate inhomogeneous dye distributions. Its applicability to real tissue is proven using reflection spectra obtained with 130 μm source‐detector separation from a hemoperfusion stop experiment. The proposed model accurately determines apparent chromophore concentrations and corresponding distributions in simulated spectra and phantoms. Regarding real tissue spectra, the results correspond to former publications and the spectral reconstruction yields only minimal residuals, indicating a complete and accurate spectral deconvolution. In conclusion, the presented approach is a suitable extension and amendment to existing models of light transport through inhomogeneous samples.
A method and software for segmentation of anatomic object ensembles by deformable m‐reps
Authors: Pizer Stephen M. , Fletcher P. Thomas , Joshi Sarang , Gash A. Graham , Stough Joshua , Thall Andrew , Tracton Gregg , Chaney Edward L.
Published: May 2005

Deformable shape models (DSMs) comprise a general approach that shows great promise for automatic image segmentation. Published studies by others and our own research results strongly suggest that segmentation of a normal or near‐normal object from 3D medical images will be most successful when the DSM approach uses (1) knowledge of the geometry of not only the target anatomic object but also the ensemble of objects providing context for the target object and (2) knowledge of the image intensities to be expected relative to the geometry of the target and contextual objects. The segmentation will be most efficient when the deformation operates at multiple object‐related scales and uses deformations that include not just local translations but the biologically important transformations of bending and twisting, i.e., local rotation, and local magnification. In computer vision an important class of DSM methods uses explicit geometric models in a Bayesian statistical framework to provide a priori information used in posterior optimization to match the DSM against a target image. In this approach a DSM of the object to be segmented is placed in the target image data and undergoes a series of rigid and nonrigid transformations that deform the model to closely match the target object. The deformation process is driven by optimizing an objective function that has terms for the geometric typicality and model‐to‐image match for each instance of the deformed model. The success of this approach depends strongly on the object representation, i.e., the structural details and parameter set for the DSM, which in turn determines the analytic form of the objective function. This paper describes a form of DSM called m‐reps that has or allows these properties, and a method of segmentation consisting of large to small scale posterior optimization of m‐reps. Segmentation by deformable m‐reps, together with the appropriate data representations, visualizations, and user interface, has been implemented in software that accomplishes 3D segmentations in a few minutes. Software for building and training models has also been developed. The methods underlying this software and its abilities are the subject of this paper.
Recommendations of the American Association of Physicists in Medicine regarding the Impact of Implementing the 2004 Task Group 43 Report on Dose Specification for and Interstitial Brachytherapy
Authors: Williamson Jeffrey F. , Butler Wayne , DeWerd Larry A. , Saiful Huq M. , Ibbott Geoffrey S. , Li Zuofeng , Mitch Michael G. , Nath Ravinder , Rivard Mark J. , Todor Dorin
Published: May 2005

In March 2004, the recommendations of the American Association of Physicists in Medicine (AAPM) on the interstitial brachytherapy dosimetry using and were reported in Medical Physics [TG‐43 Update: Rivard et al., 31, 633–674 (2004)]. These recommendations include some minor changes in the dose‐calculation formalism and a major update of the dosimetry parameters for eight widely used interstitial brachytherapy sources. A full implementation of these recommendations could result in unintended changes in delivered dose without corresponding revisions in the prescribed dose. Because most published clinical experience with permanent brachytherapy is based upon two widely used source models, the Model 6711 and Model 200 sources, in this report we present an analysis of the dosimetric impact of the 2004 TG‐43 dosimetry parameters on the history of dose delivery for these two source models. Our analysis indicates that the currently recommended prescribed dose of 125 Gy for Model 200 implants planned using previously recommended dosimetry parameters [AAPM dose prescription: Williamson et al., Med. Phys. 27, 634–642 (2000)] results in a delivered dose of 120 Gy according to dose calculations based on the 2004 TG‐43 update. Further, delivered doses prior to October 1997 varied from 113 to 119 Gy for a prescribed dose of 115 Gy compared to 124 Gy estimated by the AAPM 2000 report. For implants using Model 6711 seeds, there are no significant changes (less than 2%). Practicing physicians should take these results into account when selecting the clinically appropriate prescribed dose for interstitial implant patients following implementation of the 2004 TG‐43 update dose‐calculation recommendations. The AAPM recommends that the radiation oncology community review this report and consider whether the currently recommended dose level (125 Gy) needs to be revised.
Focal beam distortion and treatment planning in abdominal focused ultrasound surgery
Authors: Liu Hao‐Li , McDannold Nathan , Hynynen Kullervo
Published: May 2005

Recent clinical trials show promising results in using MRI and MRI‐based thermometry to guide focused ultrasound surgery to treat uterine fibroids. During treatment, large variation in the focal temperature distribution has been observed. It is possible that some of this variation is due to abdominal tissue inhomogeneity, which might be causing focal beam distortion, and might largely decrease the focusing ability in deep‐seated tissues. The purpose of this study was to numerically demonstrate this effect and also show the feasibility of restoring the focal beam patterns by employing the phase correction procedure for phased arrays. Abdominal MR data from four uterine fibroid patients were obtained to reconstruct the three‐dimensional meshes of interfaces used in simulations, and one patient was selected to perform the analysis of key parameters in focused ultrasound surgery. Results show that, without phase correction, the focused beam can be severely distorted while using a frequency above or delivering ring‐shape focal patterns. Different focal positions at the same depth may require a different power to induce the same ultrasonic intensity level (up to 179% among the different focal patterns). After adding a phase correction procedure, the distorted focal beams can be restored, and the peak intensity can be largely recovered (up to 85% among the different focal patterns). This study may offer important implications and information for treatment planning toward optimizing focused ultrasound surgery in uterine fibroid or other abdominal tumor treatments.
Improving IMRT delivery efficiency using intensity limits during inverse planning
Authors: Coselmon Martha M. , Moran Jean M. , Radawski Jeffrey D. , Fraass Benedick A.
Published: May 2005

Inverse planned intensity modulated radiotherapy (IMRT) fields can be highly modulated due to the large number of degrees of freedom involved in the inverse planning process. Additional modulation typically results in a more optimal plan, although the clinical rewards may be small or offset by additional delivery complexity and/or increased dose from transmission and leakage. Increasing modulation decreases delivery efficiency, and may lead to plans that are more sensitive to geometrical uncertainties. The purpose of this work is to assess the use of maximum intensity limits in inverse IMRT planning as a simple way to increase delivery efficiency without significantly affecting plan quality. Nine clinical cases (three each for brain, prostate, and head/neck) were used to evaluate advantages and disadvantages of limiting maximum intensity to increase delivery efficiency. IMRT plans were generated using in‐house protocol‐based constraints and objectives for the brain and head/neck, and RTOG 9406 dose volume objectives in the prostate. Each case was optimized at a series of maximum intensity ratios (the product of the maximum intensity and the number of beams divided by the prescribed dose to the target volume), and evaluated in terms of clinical metrics, dose‐volume histograms, monitor units (MU) required per fraction (SMLC and DMLC delivery), and intensity map variation (a measure of the beam modulation). In each site tested, it was possible to reduce total monitor units by constraining the maximum allowed intensity without compromising the clinical acceptability of the plan. Monitor unit reductions up to 38% were observed for SMLC delivery, while reductions up to 29% were achieved for DMLC delivery. In general, complicated geometries saw a smaller reduction in monitor units for both delivery types, although DMLC delivery required significantly more monitor units in all cases. Constraining the maximum intensity in an inverse IMRT plan is a simple way to improve delivery efficiency without compromising plan objectives.
Modality independent elastography (MIE): Potential applications in dermoscopy
Authors: Miga Michael I. , Rothney Megan P. , Ou Jao J.
Published: May 2005

The use of palpation information for skin disease characterization is not as commonly used as in other soft tissues, although mechanical differences within lesions have been noted. For example, regions of hyperkeratosis have the potential to transform into cancerous lesions and likely feature different material properties from those of surrounding normal tissue due to varying cytoarchitecture. As a result, the spatial distribution of lesion mechanical properties may serve to assist a diagnosis or enhance visualization of the complete extent of a cancerous region, i.e., accurate information regarding the margins of disease for surgical therapy. In this work, a multiresolution extension to a novel elastographic imaging method called Modality Independent Elastography (MIE) is used to characterize the mechanical properties of a skin‐like phantom embedded with a mock stiff lesion. Simulation studies were also performed to investigate the potential for characterizing realistic melanoma lesions. Elasticity image reconstructions from the phantom experiments localized the stiff inclusion and had good correlation between the Young's modulus contrast ratio and experimental measurements from material testing. In addition, multiresolution MIE was shown to be a more robust framework than its single‐resolution version. Results from the melanoma simulation demonstrate the potential for using multiresolution MIE with dermoscopic images.
Development of ultrasound tomography for breast imaging: Technical assessment
Authors: Duric Nebojsa , Littrup Peter , Babkin Alex , Chambers David , Azevedo Stephen , Kalinin Arkady , Pevzner Roman , Tokarev Mikhail , Holsapple Earle , Rama Olsi , Duncan Robert
Published: May 2005

Ultrasound imaging is widely used in medicine because of its benign characteristics and real‐time capabilities. Physics theory suggests that the application of tomographic techniques may allow ultrasound imaging to reach its full potential as a diagnostic tool allowing it to compete with other tomographic modalities such as x‐ray computer tomography, and MRI. This paper describes the construction and use of a prototype tomographic scanner and reports on the feasibility of implementing tomographic theory in practice and the potential of ultrasound (US) tomography in diagnostic imaging. Data were collected with the prototype by scanning two types of phantoms and a cadaveric breast. A specialized suite of algorithms was developed and utilized to construct images of reflectivity and sound speed from the phantom data. The basic results can be summarized as follows. (i) A fast, clinically relevant US tomography scanner can be built using existing technology. (ii) The spatial resolution, deduced from images of reflectivity, is . The demonstrated depth‐of‐field is superior to that of conventional ultrasound and the image contrast is improved through the reduction of speckle noise and overall lowering of the noise floor. (iii) Images of acoustic properties such as sound speed suggest that it is possible to measure variations in the sound speed of . An apparent correlation with x‐ray attenuation suggests that the sound speed can be used to discriminate between various types of soft tissue. (iv) Ultrasound tomography has the potential to improve diagnostic imaging in relation to breast cancer detection.
Application of acoustic reflection tomography to sonar imaging
Authors: Ferguson Brian G. , Wyber Ron J.
Published: May 2005

Computer-aided tomography is a technique for providing a two-dimensional cross-sectional view of a three-dimensional object through the digital processing of many one-dimensional views (or projections) taken at different look directions. In acoustic reflection tomography, insonifying the object and then recording the backscattered signal provides the projection information for a given look direction (or aspect angle). Processing the projection information for all possible aspect angles enables an image to be reconstructed that represents the two-dimensional spatial distribution of the object’s acoustic reflectivity function when projected on the imaging plane. The shape of an idealized object, which is an elliptical cylinder, is reconstructed by applying standard backprojection, Radon transform inversion (using both convolution and filtered backprojections), and direct Fourier inversion to simulated projection data. The relative merits of the various reconstruction algorithms are assessed and the resulting shape estimates compared. For bandpass sonar data, however, the wave number components of the acoustic reflectivity function that are outside the passband are absent. This leads to the consideration of image reconstruction for bandpass data. Tomographic image reconstruction is applied to real data collected with an ultra-wideband sonar transducer to form high-resolution acoustic images of various underwater objects when the sonar and object are widely separated.
Distortion product otoacoustic emissions for hearing threshold estimation and differentiation between middle-ear and cochlear disorders in neonates
Authors: Janssen Thomas , Gehr Daniel D. , Klein Annette , Müller Jörg
Published: May 2005

Our aim in the present study was to apply extrapolated DPOAE I/O-functions [J. Acoust. Soc. Am. 111, 1810–1818 (2002); 113, 3275–3284 (2003)] in neonates in order to investigate their ability to estimate hearing thresholds and to differentiate between middle-ear and cochlear disorders. DPOAEs were measured in neonates after birth (mean age=3.2 days) and 4 weeks later (follow-up) at 11 test frequencies between f2=1.5 and 8 kHz and compared to that found in normal hearing subjects and cochlear hearing loss patients. On average, in a single ear hearing threshold estimation was possible at about 2/3 of the test frequencies. A sufficient test performance of the approach is therefore suggested. Thresholds were higher at the first measurement compared to that found at the follow-up measurement. Since thresholds varied with frequency, transitory middle ear dysfunction due to amniotic fluid instead of cochlear immaturity is suggested to be the cause for the change in thresholds. DPOAE behavior in the neonate ears differed from that found in the cochlear hearing loss ears. From a simple model it was concluded that the difference between the estimated DPOAE threshold and the DPOAE detection threshold is able to differentiate between sound conductive and cochlear hearing loss.
Comparison of structural response and fatigue endurance of aircraft flap-like box structures subjected to acoustic loading
Authors: Xiao Y. , White R. G. , Aglietti G. S.
Published: May 2005

The results of an extensive test program to characterize the behavior of typical aircraft structures under acoustic loading and to establish their fatigue endurance are presented. The structures tested were the three flap-like box-type of structures. Each structure consisted of one flat (bottom) and one curved (top) stiffener stiffened skin panel, front, and rear spars, and ribs that divided the structures into three bays. The three structures, constructed from three different materials (aircraft standard aluminum alloy, Carbon Fibre Reinforced Plastic, and a Glass Fibre Metal Laminate, i.e., GLARE) had the same size and configuration, with only minor differences due to the use of different materials. A first set of acoustic tests with excitations of intensity ranging from 140 to 160 dB were carried out to obtain detailed data on the dynamic response of the three structures. The FE analysis of the structures is also briefly described and the results compared with the experimental data. The fatigue endurance of the structures was then determined using random acoustic excitation with an overall sound pressure level of 161 dB, and details of crack propagation are reported.
A flow waveform-matched low-dimensional glottal model based on physical knowledge
Authors: Drioli Carlo
Published: May 2005

The purpose of this study is to explore the possibility for physically based mathematical models of the voice source to accurately reproduce inverse filtered glottal volume-velocity waveforms. A low-dimensional, self-oscillating model of the glottal source with waveform-matching properties is proposed. The model relies on a lumped mechano-aerodynamic scheme loosely inspired by the one- and multimass lumped models. The vocal folds are represented by a single mechanical resonator and a propagation line which takes into account the vertical phase differences. The vocal-fold displacement is coupled to the glottal flow by means of an aerodynamic driving block which includes a general parametric nonlinear component. The principal characteristics of the flow-induced oscillations are retained, and the overall model is able to match inverse-filtered glottal flow signals. The method offers in principle the possibility of performing transformations of the glottal flow by acting on the physiologically based parameters of the model. This is a desirable property, e.g., for speech synthesis applications. The model was tested on a data set which included inverse-filtered glottal flow waveforms of different characteristics. The results demonstrate the possibility of reproducing natural speech waveforms with high accuracy, and of controlling important characteristics of the synthesis such as pitch.
Two-dimensional model of vocal fold vibration for sound synthesis of voice and soprano singing
Authors: Adachi Seiji , Yu Jason
Published: May 2005

Voiced sounds were simulated with a computer model of the vocal fold composed of a single mass vibrating both parallel and perpendicular to the airflow. Similarities with the two-mass model are found in the amplitudes of the glottal area and the glottal volume flow velocity, the variation in the volume flow waveform with the vocal tract shape, and the dependence of the oscillation amplitude upon the average opening area of the glottis, among other similar features. A few dissimilarities are also found in the more symmetric glottal and volume flow waveforms in the rising and falling phases. The major improvement of the present model over the two-mass model is that it yields a smooth transition between oscillations with an inductive load and a capacitive load of the vocal tract with no sudden jumps in the vibration frequency. Self-excitation is possible both below and above the first formant frequency of the vocal tract. By taking advantage of the wider continuous frequency range, the two-dimensional model can successfully be applied to the sound synthesis of a high-pitched soprano singing, where the fundamental frequency sometimes exceeds the first formant frequency.
Sensory and nonsensory influences on children’s performance of dichotic pitch perception tasks
Authors: Edwards Veronica T. , Giaschi Deborah E. , Low Pauline , Edgell Dorothy
Published: May 2005

Dichotic pitch perception reflects the auditory system’s use of binaural cues to perceptually separate different sound sources and to determine the spatial location of sounds. Several studies were conducted to identify factors that influence children’s dichotic pitch perception thresholds. An initial study of school children revealed an age-related improvement in thresholds for lateralizing dichotic pitch tones. In subsequent studies potential sensory and nonsensory limitations on young children’s performance of dichotic pitch lateralization tasks were examined. A training study showed that with sufficient practice, young children lateralize dichotic pitch stimuli as well as adults, indicating an age difference in perceptual learning of the lateralization task. Changing the task requirements so that young children made a judgment about the pitch of dichotic pitch tones, rather than the spatial location of the tones, also resulted in significantly better thresholds. These findings indicate that nonsensory factors limit young children’s performance of dichotic pitch tasks.
Observer weighting strategies in interaural time-difference discrimination and monaural level discrimination for a multi-tone complex
Authors: Dye Raymond H. , Stellmack Mark A. , Jurcin Noah F.
Published: May 2005

Two experiments measured listeners’ abilities to weight information from different components in a complex of 553, 753, and 953 Hz. The goal was to determine whether or not the ability to adjust perceptual weights generalized across tasks. Weights were measured by binary logistic regression between stimulus values that were sampled from Gaussian distributions and listeners’ responses. The first task was interaural time discrimination in which listeners judged the laterality of the target component. The second task was monaural level discrimination in which listeners indicated whether the level of the target component decreased or increased across two intervals. For both experiments, each of the three components served as the target. Ten listeners participated in both experiments. The results showed that those individuals who adjusted perceptual weights in the interaural time experiment could also do so in the monaural level discrimination task. The fact that the same individuals appeared to be analytic in both tasks is an indication that the weights measure the ability to attend to a particular region of the spectrum while ignoring other spectral regions.
Temporal onset-order discrimination through the tactual sense
Authors: Yuan Hanfeng , Reed Charlotte M. , Durlach Nathaniel I.
Published: May 2005

Tactual temporal-onset order thresholds were measured for two sinusoidal vibrations of different frequencies delivered to two separate locations (thumb and index finger) of a multi-finger tactual stimulating device. The frequency delivered to the thumb was fixed at 50 Hz and that to the index finger at 250 Hz. The amplitude and duration of each of the two sinusoidal vibrations were roved independently from trial to trial in a 1-interval, 2AFC procedure. Performance, measured as a function of stimulus-onset asynchrony (SOA), indicated that the temporal-onset-order threshold averaged 34 ms across four subjects. The data were further classified into subsets according to both the amplitude and duration of the two stimuli in each trial of the roving-discrimination paradigm. The results indicated that the amplitude differences of the two stimuli in each trial had a substantial effect on onset-order discrimination, while duration differences generally had little effect. The effects of amplitude differences are explained qualitatively in terms of amplitude latency relationships and stimulus interactions such as temporal masking. Overall, the results not only contribute to an enhanced understanding of the temporal sensitivity of the tactual system but also provide guidelines for the design of tactual aids for hearing-impaired persons.
A parametric model of the vocal tract area function for vowel and consonant simulation
Authors: Story Brad H.
Published: May 2005

A model of the vocal-tract area function is described that consists of four tiers. The first tier is a vowel substrate defined by a system of spatial eigenmodes and a neutral area function determined from MRI-based vocal-tract data. The input parameters to the first tier are coefficient values that, when multiplied by the appropriate eigenmode and added to the neutral area function, construct a desired vowel. The second tier consists of a consonant shaping function defined along the length of the vocal tract that can be used to modify the vowel substrate such that a constriction is formed. Input parameters consist of the location, area, and range of the constriction. Location and area roughly correspond to the standard phonetic specifications of place and degree of constriction, whereas the range defines the amount of vocal-tract length over which the constriction will influence the tract shape. The third tier allows length modifications for articulatory maneuvers such as lip rounding/spreading and larynx lowering/raising. Finally, the fourth tier provides control of the level of acoustic coupling of the vocal tract to the nasal tract. All parameters can be specified either as static or time varying, which allows for multiple levels of coarticulation or coproduction.
Medial surface dynamics of anin vivocanine vocal fold during phonation
Authors: Döllinger Michael , Berry David A. , Berke Gerald S.
Published: May 2005

Quantitative measurement of the medial surface dynamics of the vocal folds is important for understanding how sound is generated within the larynx. Building upon previous excised hemilarynx studies, the present study extended the hemilarynx methodology to the in vivo canine larynx. Through use of an in vivo model, the medial surface dynamics of the vocal fold were examined as a function of active thyroarytenoid muscle contraction. Data were collected using high-speed digital imaging at a sampling frequency of 2000 Hz, and a spatial resolution of 1024×1024 pixels. Chest-like and fry-like vibrations were observed, but could not be distinguished based on the input stimulation current to the recurrent laryngeal nerve. The subglottal pressure did distinguish the registers, as did an estimate of the thyroarytenoid muscle activity. Upon quantification of the three-dimensional motion, the method of Empirical Eigenfunctions was used to extract the underlying modes of vibration, and to investigate mechanisms of sustained oscillation. Results were compared with previous findings from excised larynx experiments and theoretical models.
The effects of tones on speaking frequency and intensity ranges in Mandarin and Min dialects
Authors: Chen Sheng H.
Published: May 2005

The differences of speaking frequency and intensity in different tonal dialects has not been widely investigated. The purposes of this study were (1) to compare the speaking frequency and speaking intensity ranges of Mandarin and Min and (2) to compare the speaking frequency and intensity ranges of Mandarin and Min to those of American English. The subjects were 80 normal Taiwanese adults divided into two dialect groups, Mandarin and Min. The speaking F0, the highest speaking F0, the lowest speaking F0, the maximum range of speaking F0, and the intensity counterpart were obtained from reading in their native dialects. Statistical analysis revealed that Min speakers had a significantly greater maximum range of speaking intensity and a smaller lowest speaking intensity than Mandarin speakers, which indicated tonal effects by speakers of the Min dialect. Moreover, Mandarin and Min speakers had a greater maximum range of speaking F0 and maximum range of speaking intensity than American English speakers. The data may provide an assessment tool for Mandarin speakers and Min speakers.
Contactless micromanipulation of small particles by an ultrasound field excited by a vibrating body
Authors: Haake Albrecht , Dual Jurg
Published: May 2005

A method is presented to position and displace micron-sized particles of a diameter between 10 and 100 μm without contact to solid instruments. An ultrasound field is utilized for this purpose. It is excited in a fluid-filled gap between a harmonically vibrating body and a rigid plane surface of an arbitrary other body, e.g., an object slide or a wafer. In this ultrasound field a force field is established, which acts on the particles suspended in the fluid and moves them to certain positions. The advantage of the method is that it is possible to manipulate single particles or many particles in parallel on any surface, for example, on a structured wafer. Theoretical calculations of the force field and experimental results including three principles to displace particles with micrometer accuracy are shown. The method might be used for microassembly or cell manipulation and treatment.
Pitch ranking ability of cochlear implant recipients: A comparison of sound-processing strategies
Authors: Vandali Andrew E. , Sucher Catherine , Tsang David J. , McKay Colette M. , Chew Jason W. D. , McDermott Hugh J.
Published: May 2005

Pitch ranking of sung vowel stimuli, separated in fundamental frequency (F0) by half an octave, was measured with a group of eleven Nucleus 24 cochlear implant recipients using different sound coding strategies. In three consecutive studies, either two or three different sound coding strategies were compared to the Advanced Combinational Encoder (ACE) strategy. These strategies included Continuous Interleaved Sampling (CIS), Peak Derived Timing (PDT), Modulation Depth Enhancement (MDE), F0 Synchronized ACE (F0Sync), and Multi-channel Envelope Modulation (MEM), the last four being experimental strategies. While pitch ranking results on average were poor compared to those expected for most normal hearing listeners, significantly higher scores were obtained using the MEM, MDE, and F0Sync strategies compared to ACE. These strategies enhanced coding of temporal F0 cues by providing deeper modulation cues to F0 coincidentally in time across all activated electrodes. In the final study, speech recognition tests were also conducted using ACE, CIS, MDE, and MEM. Similar results among all strategies were obtained for word tests in quiet and between ACE and MEM for sentence tests in noise. These findings demonstrate that strategies such as MEM may aid perception of pitch and still adequately code segmental speech features as per existing coding strategies.
Hilbert space inverse wave imaging in a planar multilayer environment
Authors: Lehman Sean K.
Published: May 2005

Most diffraction tomography (DT) algorithms use a homogeneous Green function (GF) regardless of the medium being imaged. This choice is usually motivated by practical considerations: analytic inversions in standard geometries (Cartesian, spherical, etc.) are significantly simplified by the use of a homogeneous GF, estimating a nonhomogeneous GF can be very difficult, as can incorporating a nonhomogeneous GF into standard DT algorithms. Devaney has circumvented these issues by developing a purely numerical DT inversion algorithm [A. J. Devaney and M. Dennison, Inverse Probl. 19, 855–870 (2003)] that is independent of measurement system geometry, number of frequencies used in the reconstruction, and GF. A planar multilayer GF has been developed for use in Devaney’s “Hilbert space” algorithm and used in a proof-of-principle nondestructive evaluation (NDE) experiment to image noninvasively a flaw in an aluminum/copper planar multilayer medium using data collected from an ultrasonic measurement system. The data were collected in a multistatic method with no beamforming: all focusing through the multilayer was performed mathematically “after-the-fact,” that is, after the data were collected.
Optimization of angular and frequency compounding in ultrasonic attenuation estimations
Authors: Tu Haifeng , Zagzebski James A. , Gerig Anthony L. , Chen Quan , Madsen Ernest L. , Hall Timothy J.
Published: May 2005

Previous reports have shown that the variance in ultrasound attenuation measurements is reduced when spatial and frequency compounding were applied in data acquisition and analysis. This paper investigates factors affecting the efficiency of compound attenuation imaging methods. A theoretical expression is derived that predicts the correlation between attenuation versus frequency slope (β) estimates as a function of the increment between measurement frequencies (Δf ) and the angular separation between beam lines (Δθ). Theoretical results are compared with those from attenuation measurements on tissue-mimicking phantoms and from simulation data. Both predictions and measurement results show that the correlation between β estimates as a function of (Δf ) is independent of the length of the radio frequency (rf) data segment over which β is derived. However, it decreases with an increase in the length of the data segment used in power spectra estimates. In contrast, the correlation between β estimates as a function of Δθ decreases when the rf data segment length is longer or the frequency of the signal is higher.
Evoked-potential audiogram of the Yangtze finless porpoise Neophocaena phocaenoides asiaeorientalis (L)
Authors: Popov Vladimir V. , Supin Alexander Ya. , Wang Ding , Wang Kexiong , Xiao Jianqiang , Li Songhai
Published: May 2005

Evoked-potential audiograms were obtained in two (one male and one female) Yangtze finless porpoises, Neophocaena phocaenoides asiaseorientalis. Sinusoidal amplitude-modulated 20-ms tone bursts were used as probes with recording envelope-following evoked potentials. A frequency range of 8 to 152 kHz was investigated. The range of greatest sensitivity covered frequencies from 45 to 139 kHz, and the lowest thresholds of 47.2 and 48.5 dB re: 1 μPa were found at a frequency of 54 kHz in the two subjects, respectively. At lower frequencies, threshold increased with a rate of around 14 dB/octave, and threshold steeply increased at 152 kHz.
Locally periodic Timoshenko rod: Experiment and theory
Authors: Dı́az-de-Anda A. , Pimentel A. , Flores J. , Morales A. , Gutiérrez L. , Méndez-Sánchez R. A.
Published: May 2005

The flexural vibrations of a locally periodic rod, which consists of N unit cells, are discussed both from the experimental and theoretical points of view. Timoshenko’s beam theory and the transfer matrix method are used to calculate the normal-mode frequencies and amplitudes. The theoretical values are then compared with the experimental ones, which are obtained using an electromagnetic acoustic transducer (EMAT). Good agreement between the numerical results and the experimental measurements is obtained. It is shown that as N grows, a band spectrum emerges.
A unified view of imaging the elastic properties of tissue
Authors: Parker Kevin J. , Taylor Lawrence S. , Gracewski Sheryl , Rubens Deborah J.
Published: May 2005

A number of different approaches have been developed to estimate and image the elastic properties of tissue. The biomechanical properties of tissues are vitally linked to function and pathology, but cannot be directly assessed by conventional ultrasound, MRI, CT, or nuclear imaging. Research developments have introduced new approaches, using either MRI or ultrasound to image the tissue response to some stimulus. A wide range of stimuli has been evaluated, including heat, water jets, vibration shear waves, compression, and quasistatic compression, using single or multiple steps or low-frequency (<10 Hz) cyclic excitation. These may seem to be greatly dissimilar, and appear to produce distinctly different types of information and images. However, our purpose in this tutorial is to review the major classes of excitation stimuli, and then to demonstrate that they produce responses that fall within a common spectrum of elastic behavior. Within this spectrum, the major classes of excitation include step compression, cyclic quasistatic compression, harmonic shear wave excitation, and transient shear wave excitation. The information they reveal about the unknown elastic distribution within an imaging region of interest are shown to be fundamentally related because the tissue responses are governed by the same equation. Examples use simple geometry to emphasize the common nature of the approaches.