bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimal integration of directional information across a population of simple MSO neurons
Authors: Lubensky Sergei , Shinn-Cunningham Barbara G. , Colburn H. Steven , Durlach Nathaniel I.
Published: July 2002

A simple computational model of source laterality was developed that optimally combines information across a population of neurons in the medial superior olive. A simple point-neuron MSO model was used to simulate the output of each of the interaural-phase sensitive neurons in the population. Each neuron has a best frequency and best interaural phase delay (IPD), generating an intermediate display similar to that proposed by Colburn [J. Acoust. Soc. Am. 61, 525–533 (1977)]. Information in this population was combined (i.e., across best frequency and best IPD) to determine the a posteriori probability of a source from each possible angle relative to the interaural axis. From this output, source laterality was predicted from the maximum likelihood estimate of source direction. Similar to previous models [R. M. Stern and C. Trahiotis, Proceedings 11th International Symposium on Hearing (1997), pp. 336–345], this approach looks for consistency in the neural responses across frequency. However, the current model explicitly weights information corresponding to different best frequencies and IPDs based on the uncertainty in the responses of the neurons in the population. Lateralization predictions were generated for a variety of sources and compared with results from the literature. [Work supported in part by AFOSR Grant No. F49620-98-1-0108.]
Perceptual segregation of individual components from a complex tone via changes in interaural time delay (ITD)
Authors: Culling John F.
Published: July 2002

When all the components of a complex tone share a common interaural time delay (ITD), a single component can be made to perceptually segregate from the complex by shifting its ITD to a unique value. Segregation of different components in succession can evoke the perception of a melody [Kubovy et al., Science 186, 272–274]. A series of five experiments demonstrated that (1) the ITD transition is more responsible for the segregation effect than the uniqueness of the ITD of the segregated component, (2) independent change in ITD of one component relative to coherent change among the other components is not sufficient to cause segregation, (3) cyclic modulation of ITD causes segregation which is independent of modulation rate, (4) temporal gaps in the stimulus of the order of 100 ms, and centered on the ITD transitions, can prevent segregation. These findings are consistent with an explanation based on sensitivity to within-channel reductions in interaural correlation within a sliding temporal window of around 100-ms duration; when different ITDs are temporally juxtaposed within a time frame of around 100 ms, these ITDs are encompassed by the window’s span and the wave forms within it do not correlate perfectly at either delay.
Progress toward a ‘‘smart acoustic blanket.’’
Authors: Bucaro Joseph A. , Houston Brian H. , Howarth Thomas , Corsaro Robert , Tressler James , Lagakos Nicholas
Published: July 2002

This paper presents recent progress we have made toward the goal of developing what we call ‘‘smart acoustic blankets.’’ Such technology would have application in many acoustic areas including aeroacoustics, architectural acoustics, and traffic sound barriers in addition to our principal focus which is the reduction of launch noise sound transmission through satellite payload fairings. These smart blankets would be configured with sound actuation layers, acoustic pressure and velocity sensors, and electronic controller modules. The status of the development of each of these components as well as the overall concept will be discussed. [Work supported by ONR.]
Active vibration control of a structure using virtual sensors
Authors: Dias Vivian F. , Sommerfeldt Scott D.
Published: July 2002

Presently, a large safety factor is used in determining routine maintenance schedules for critical machinery/parts, such as replacement of skins for aircraft wings, because any failure during operation could prove catastrophic. Assuming that the location of the structural damage can be identified at its inception, one could apply active vibration control on the structure as a means of reducing stresses in the damage zone, thus ensuring that the damage does not grow rapidly with time. However, the probability of having an error sensor at the damage location is small, which indicates that a different approach would be required for implementing the active control. Work will be reported aimed at developing an active vibration control system that allows the control to minimize the stress or vibration at any arbitrary point/zone on the vibrating structure, even where there is no error sensor present. This is accomplished by using what are referred to as ‘‘virtual sensors.’’ These virtual sensors use information from physical sensors at other locations on the structure to estimate the vibration response at the virtual sensor location. This approach offers the possibility of being able to control the structural vibration at any desired, arbitrary location on the structure.
Age-related differences in regularity of speech rate
Authors: Morris Richard J.
Published: July 2002

Older adults speak more slowly and exhibit greater speaking rate variability than do young adults [i.e., Liss et al., J. Geron. 45, P35–45 (1990); Ramig, J. Commun. Disord. 16, 217–226 (1983)]. These findings have been reported for rates of speech, articulation, and reading as well as for individual consonants and vowels. However, one recent work found that their group of older adults exhibited greater regularity in their repetition of syllables [Watson and Fozo, ASLHA Conv. (November, 1999)]. These authors hypothesized that the older speakers may have less flexibility in the timing of their speech. The purpose of the present study was to test the hypothesis of reduced timing flexibility in the speech of older people. Ten older men and ten younger men served as subjects for this study. All subjects were in good general health and had normal hearing for their age. The subjects were directed to repeat a series of single syllable words, pat’, bat’, sack’ and shack’, at slow, normal and fast rates. The speech was recorded onto a DAT recorder and analyzed using the CSpeech software. Results are discussed in terms of age differences in speech timing across the three speaking conditions.
Lexical access in a divided attention task: Evidence from a new verbal transformation methodology
Authors: Lenz Peter W. , Warren Richard M. , Bashford James A.
Published: July 2002

A recorded repeating word undergoes illusory changes (Verbal Transformations, or VTs) to forms consisting of syllables and words occurring in the listener’s lexicon. When the repeating word is delivered dichotically with a long interaural delay, the listener hears two distinct lateralized images, each changing independently [see Warren and Ackroff, Nature (London) 259, 475–477 (1976)]. The present study introduces a new methodology minimizing vigilance and memory demands posed by the traditional VT paradigm. Rather than continuous monitoring and reporting of changes occurring on each side, listeners simply reported the forms being heard when cued by a light flash. In keeping with earlier findings based upon continuous bilateral monitoring, the simultaneous organizations of the same word were found to change independently. Contrasting with earlier studies, however, the presence of a second image of the same word did not decrease the transition rate, presumably due to reduced task demands. Interestingly, the transition rate decreased dramatically when two different repeating words were presented. Implications of these findings regarding mechanisms employed in processing speech will be discussed. [Work supported by NIH.]
Phonetic metamorphosis of white noise: A stop or a fricative
Authors: Shafiro Valeriy
Published: July 2002

The role of spectro-temporal coherence, lexical status, and word position in the perception of speech in acoustic signals containing a mixture of speech and nonspeech sounds was investigated. Stimuli consisted of nine words in which either white noise was inserted only into the silent interval preceding the onset of vocalic transitions ambiguous between /p/ and /f/, or in which white noise was mixed with the entire speech signal. A control condition contained no noise. Ten adults were asked to decide whether they heard a word with a /p/ or /f/ as the phoneme in the initial, medial, or final word position. The subjects perceived /f/’s 85% of the time when noise was inserted into the silent interval, 47% when noise was presented over the entire word, and 1% in the control condition. These results indicate the importance of spectro-temporal coherence for perceiving speech in a mixture of sounds. The lexical status and position of the critical phoneme in the stimuli also appeared to affect subjects’ responses, although to a smaller degree. Theoretically, the results support the auditory scene analysis view of perceiving speech in heterogeneous signals, while they cannot be adequately explained by the motor theory of speech perception.
Optimal classroom design applied in the OSU Fisher School of Business Graduate Studies Gerlach Hall
Authors: Campanella Angelo
Published: July 2002

On endowing the recent expansion of the Ohio State University College of Business, Max M. Fisher said that his interest was not in buildings; they did not excite him. Rather, his interest was in value-added programs to improve the product, education in this case. We followed this philosophy in the architectural acoustics design. The graduate studies program included many classrooms of 40 to 100 seat capacity, as well as stock market and communications laboratories. The classrooms were to include distance learning that required teleconferencing capability. To these ends, all classrooms were designed for NC-25 background noise and [1+log(V)]/10 reverberation time. Measurements of the background noise of three classrooms and the reverberation time of one classroom are presented. In October 1998 associate professor David Greenberger remarked ‘‘The acoustics are awesome. Anyone can hear you if you talk in a soft voice. That’s great for faculty.’’
Bioacoustic absorptivity and transmission loss in littoral seas
Authors: Diachok Orest
Published: July 2002

Long-term, broadband measurements of transmission loss, TL, between a fixed source and a fixed receiver in littoral seas, permit isolation of the effects of bioacoustic absorptivity, αb, from other environmental effects on TL. Concurrent echo sounder measurements and biological sampling facilitate classification of the causes of observed absorption lines. Frequencies of maximum αb at night, when pelagic fish are predominantly dispersed near the surface, are consistent with a modified form of Minnaert’s equation for the resonance frequency of bubbles, f0, where the inputs are the effective radius and eccentricity of swim bladders. Frequencies of maximum αb during the day, when pelagic fish are predominantly in schools near the bottom, are downshifted, relative to Minnaert’s equation, due to the collective oscillations of schools (Diachok, 1999). The magnitude of αb at f0 (at night) is a function of the number density, n (number/m3), and other bioacoustic parameters. Nearly coincident absorption and echo sounder based estimates of n have been shown to be consistent (Diachok, Liorzou, and Scalabrin, 2000). The implications of these results for the design of the next generation of long-term, broadband transmission loss experiments in littoral seas where n is high, such as the seas off California and China, will be reviewed.
Acoustic propagation measurements in the surf
Authors: Commander Kerry W. , Stroud John S.
Published: July 2002

As part of the 1999 Near Shore Acoustic Network Experiment (NSANE), conducted off of the Scripps Institute of Oceanography pier in La Jolla, CA, measurements were conducted in a very shallow water (VSW)/surf zone (SZ) region to investigate acoustic propagation and coherence in coastal areas. These measurements utilized an acoustical array of 16 hydrophones (supplied by Bethnos, formerly Datasonics, Inc.) deployed over many tens of meters, and a broadband source. The data to be presented were acquired from hydrophones on two vertical arrays, separated by 240 m, which comprised half of the total array. The broadband projector was operated in the 3.5- to 28-kHz range using a variety of pulse types. The projector was aimed seaward, as it was located closer to shore than any of the receivers. Data were acquired in conjunction with environmental data by other NSANE team members. The data were analyzed using coherence techniques. Results of this acoustic measurement for select pulse types will be reported. [Work supported by ONR Code 321OE.]
Modal adiabaticity in shallow water. Part I: Volume interaction
Authors: Shang E. C. , Wang Y. Y.
Published: July 2002

To assess the modal adiabaticity of sound propagation in the ocean is crucial both for acoustic field prediction (forward problem) and tomographic retrieving (inverse problem). Most of the criteria in the literature is too restrictive (conservative). A new criterion of the modal adiabaticity for volume interaction is proposed in this paper. The adiabaticity of two strong volume interaction cases in shallow water has been estimated based on the new criterion: (1) the Polar front case, and (2) the solitary wave case. The results assessed by the criterion have been verified numerically by processing the modal decomposition of the PE field. It is found that the adiabatic modes can survive in a narrow belt along the ‘‘cutoff’’ line in the ‘‘m−f’’ (mode number−frequency) plan for these two strong volume interaction cases. [Work supported by ONR and NOAA.]
Hot topics in engineering acoustics
Authors: Howarth Thomas R.
Published: July 2002

Underwater acoustic transduction has been undergoing great changes in modern device designs. After several decades of advancements in acoustic sensing technologies, current interests have included novel and application-specific designs in underwater acoustic projection. These changes are an outgrowth of advances in materials processing and manufacturing. The incorporation of newer materials is resulting in devices that are specifically tailored for individual applications as opposed to general designs that in the past have been used to cover a variety of applications. This presentation will introduce the concepts of the new materials advances, including piezocomposites, piezopolymers, electrostrictive ceramics, single crystals, hybrid piezoelectric ceramic/magnetostriction devices, and microflextensional drivers called cymbals. The state of development of these technologies will be introduced as they are being incorporated into new devices. The talk will show prototype designs and discuss future directions. [The continuing support of ONR 321 is gratefully acknowledged.]
Hot topics in underwater acoustics
Authors: Frisk George V.
Published: July 2002

The field of underwater acoustics has reached a level of maturity that enables it to lay claim to offspring such as acoustical oceanography and animal bioacoustics. This maturity should by no means be equated with stagnation, however, for the classical discipline of ocean acoustics remains a lively, active, and vibrant area of research. It continues to generate exciting results through its unique combination of wave propagation physical, signal processing, and at-sea experimentation. In recent years, the field has benefited enormously from scientific advances in oceanography and geophysics, as well as technological developments such as the Global Positioning System and microchip hardware. Current research activities in underwater acoustics embrace a wide band of frequencies, from tens of hertz to hundreds of kilohertz, and a broad range of oceanographic environments, from the surf zone to the deep ocean. Some of these exciting developments are reviewed in this paper.
The closed quotient as a factor in the singing voice
Authors: Miller Donald G. , Schutte Harm K.
Published: July 2002

The closed quotient (CQ), or percentage of the glottal cycle in which airflow is prevented by the contiguous vocal folds, has been a relatively neglected entity in recent literature on the singing voice. This descriptive paper considers the estimation of the closed quotient (CQ) through electroglottography, the audio signal, and videokymography; the factor of CQ in register, type of singing voice, and characteristic resonance strategies in singing; and phase relationships of glottal closing and opening with subglottal and supraglottal pressure waves, and especially with the driving of the dominant standing wave of the vocal tract. The degree of acoustic coupling between the spaces above and below the glottis is examined on the basis of broadband signals from pressure transducers mounted on a catheter passed through the posterior commissure of the glottis.
Optical manipulation of bubbles in water using solid-state laser technology
Authors: Jian Pey-Schuan , Torruellas William E. , Thiessen David B. , Marston Philip L.
Published: July 2002

For some experiments on the acoustics of bubbles in water, it may be desirable to counter buoyancy using optical radiation pressure. A previous demonstration of the optical trapping of small bubbles that would have otherwise been freely rising used a green continuous downward-directed beam from an Ar-ion gas laser having an irradiance minimum on the beam axis [B. T. Unger and P. L. Marston, J. Acoust. Soc. Am. 83, 970–975 (1988)]. Some of the difficulties in using solid-state laser technology for this purpose are that the beam should be green (to minimize absorption) and have an axial irradiance minimum (for lateral stability). We have generated the required beam using a diode-pumped Nd:YVO4 laser crystal with intracavity-second-harmonic-generation in a lithium-tri-borate crystal. The 5.5-W external green beam power levels achievable were more than sufficient for suspension of gas bubbles having 20- and 40-μm radii generated by electrolysis. The bubble size is measured using forward scattering. Occasionally, two vertically offset bubbles can be trapped along the axis of the downward directed beam. [Work supported by NASA.]
Geological analysis of acoustic subbottom profiles as a tool for prediction of acoustic property distribution
Authors: Bartek Louis R.
Published: July 2002

Geoscientists have developed analytical techniques for extraction of geologic and acoustic data from acoustic profiles as well as prediction of how these properties may vary in areas where data are lacking and therefore these may be of interest to acousticians. Analysis of reflection termination patterns in subbottom profile data are used to identify sediment deposited contemporaneously by a set of related depositional environments. A variation in the interval that separates reflections is usually related to a change in bed thickness. Closely spaced reflections are associated with environments of deposition where the mode of deposition changes frequently and those with widely spaced reflections are associated with environments where the mode of deposition rarely changes. Continuity of reflections is related to the lateral continuity of beds. Environments that have relatively short lateral continuity, such as terrestrial environments like river valleys that have been flooded, and many marginal marine environments are associated with reflections that have relatively short lateral continuity. These variations in separation and lateral continuity of beds and termination and orientation of beds that are all linked to variations in reflection character are produced by depositional processes that are associated with depositional systems and therefore distributed in a relatively predictable manner.
A comparison of linguistic and pathological breathiness using the LF model
Authors: Epstein Melissa A.
Published: July 2002

This study investigated the hypothesis that breathiness used contrastively or to enhance a contrast in a language is as ‘‘breathy’’ as breathiness resulting from vocal pathology. Vowel samples were taken from four male and four female native speakers of English and four male and four female speakers with pathologically breathy voices. In the English data, a single pitch period was extracted and analyzed from an allophonically modal sample (following /ʔ/), a vowel-initial allophonically breathy sample (following /h/), and a vowel-medial allophonically breathy sample. A representative vowel-medial cycle was selected for speakers with vocal pathology. To determine relative breathiness, vowels were inverse filtered and fit with the LF model of the glottal flow derivative; measurements of open quotient, glottal skew, excitation strength (Ee) and the shape of the return phase were made from the LF smoothed pulses. Breathiness occurring allophonically after intervocalic /h/ did not differ significantly on any parameter from the vowels produced by speakers with pathologically breathy voices. EE proved to be the best measure of relative breathiness. It distinguished the pathological samples from the normal samples (allophonically modal and allophonically breathy together); it also distinguished the allophonically breathy samples from the allophonically modal samples.
Variational formulations for sound in enclosed spaces and ducts
Authors: Zampolli Mario , Pierce Allan D. , Cleveland Robin O.
Published: July 2002

The present formulation differs from those appearing in earlier literature in that the boundary conditions are explicitly incorporated, so that not all admissible trial functions need to satisfy them. If the class of considered trial functions is restricted so that each is a finite sum of simple functions with arbitrary coefficients, then the answer selected by the variational principle attempts to satisfy the boundary conditions plus the partial differential equations imposed in the interior simultaneously, but only achieves a trade-off. An example is a waveguide of variable cross section, with one end open and the other closed. The Rayleigh integral solution for sound radiated by a baffled aperture with an arbitrary distribution of velocity amplitude on the aperture yields the open-end boundary conditions. Individual trial functions are combinations of cross-sectional mode-shape functions with axially dependent coefficients. Numerical instabilities encountered in previous direct integration of the coupled-mode equations are avoided by taking the axial coefficient functions to be piecewise linearly along the axis. The amplitudes at the nodal points satisfy a sparse system of linear algebraic equations, this system resulting directly from the variational principle. [Work supported by DARPA/USNWRC.]
Field measurements of sonic boom penetration into the ocean
Authors: Sohn R. A. , Vernon F. , Hildebrand J. A. , Webb S. C.
Published: July 2002

Six sonic booms, generated by F-4 aircraft under steady flight at a range of altitudes (610–6100 m) and Mach numbers (1.07–1.26), were measured just above the air/sea interface, and at five depths in the water column. The measurements were made with a vertical hydrophone array suspended from a small spar buoy at the sea surface, and telemetered to a nearby research vessel. The sonic boom pressure amplitude decays exponentially with depth, and the signal fades into the ambient noise field by 30–50 m, depending on the strength of the boom at the sea surface. Low-frequency components of the boom waveform penetrate significantly deeper than high frequencies. Frequencies greater than 20 Hz are difficult to observe at depths greater than about 10 m. Underwater sonic boom pressure measurements exhibit excellent agreement with predictions from analytical theory, despite the assumption of a flat air/sea interface. Significant scattering of the sonic boom signal by the rough ocean surface is not detected. Real ocean conditions appear to exert a negligible effect on the penetration of sonic booms into the ocean unless steady vehicle speeds exceed Mach 3, when the boom incidence angle is sufficient to cause scattering on realistic open ocean surfaces.
An analytical error invalidates the “depolarization” of the perceptual magnet effect
Authors: Guenther Frank H.
Published: July 2002

In a recent article, Lotto et al. [J. Acoust. Soc. Am. 103, 3648–3655 (1998)] presented experiments investigating the role played by perceived phonemic identity in demonstrations of decreased discriminability for prototypical vowel sounds. The authors interpreted their results as evidence against shrinkage of perceptual space near vowel category prototypes. In this letter, it is shown that this interpretation is based on a flawed data analysis in which a key confounding term has been neglected.
Reply to “An analytical error invalidates the ‘depolarization’ of the perceptual magnet effect” [J. Acoust. Soc. Am. 107, 3576–3577 (2000)]
Authors: Lotto Andrew J.
Published: July 2002

In a previous paper, Lotto et al. [J. Acoust. Soc. Am. 103, 3648–3655 (1998)] claimed that experiments investigating a perceptual magnet effect (PME) failed to demonstrate a novel effect of goodness judgments on speech sound discrimination due to a confound in the procedure. New analyses of these data and a review of the recent literature fail once again to support the existence of PME.
Acoustical wave propagator
Authors: Pan J. , Wang J. B.
Published: July 2002

In this paper, an explicit acoustical wave propagator (AWP) is introduced to described the time-domain evolution of acoustical waves. To implement its operation on an initial state of wave motion, the acoustical wave propagator is approximated as a Chebyshev polynomial expansion, which converges to machine accuracy. The spatial gradient in each polynomial term is evaluated by a Fourier transformation scheme. Analysis and numerical examples demonstrated that this Chebyshev–Fourier scheme is highly accurate and computational effective in predicting time-domain acoustical wave propagation and scattering.
Investigation of active structural intensity control in finite beams: Theory and experiment
Authors: Audrain P. , Masson P. , Berry A.
Published: July 2002

An investigation of structural intensity control is presented in this paper. As opposed to previous work, the instantaneous intensity is completely taken into account in the control algorithm, i.e., all the terms are considered in the real-time control process and, in particular, the evanescent waves are considered in this approach. A finite difference approach using five accelerometers is used as the sensing scheme. A feedforward filtered-X least mean square algorithm is adapted to this energy-based control problem, involving a nonpositive definite quadratic form in general. In this respect, the approach is limited to cases where the geometry is such that the intensity component will have the same sign for the control source and the primary disturbance. Results from numerical simulations are first presented to illustrate the benefit of using a cost function based on structural intensity. Experimental validation of the approach is conducted on a free–free beam covered with viscoelastic material. A comparison is made between classical acceleration control and structural intensity control and the performance of both approaches is presented. These results confirm that using intensity control allows the error sensors to be placed closer to the control source and the primary disturbance, while preserving a good control performance.
An analysis of quasi-frequency-modulated noise and random-sideband noise as comparisons for amplitude-modulated noise
Authors: Strickland Elizabeth A. , Dhar Sumit
Published: July 2002

Experiments were performed to determine under what conditions quasi-frequency-modulated (QFM) noise and random-sideband noise are suitable comparisons for AM noise in measuring a temporal modulation transfer function (TMTF). Thresholds were measured for discrimination of QFM from random-sideband noise and AM from QFM noise as a function of sideband separation. In the first experiment, the upper spectral edge of the noise stimuli was at 2400 Hz and the bandwidth was 1600 Hz. For sideband separations up to 256 Hz, at threshold sideband levels for discriminating AM from QFM noise, QFM was indiscriminable from random-sideband noise. For the largest sideband separation used (512 Hz), listeners may have used within-stimulus envelope correlation in the QFM noise to discriminate it from the random-sideband noise. Results when stimulus bandwidth was varied suggest that listeners were able to use this cue when the carrier was wider than a critical band, and the sideband separation approached the carrier bandwidth. Within-stimulus envelope correlation was also present in AM noise, and thus QFM noise was a suitable comparison because it made this cue unusable and forced listeners to use across-stimulus envelope differences. When the carrier bandwidth was less than a critical band or was wideband, QFM noise and random-sideband noise were equally suitable comparisons for AM noise. When discrimination thresholds for QFM and random-sideband noise were converted to modulation depth and modulation frequency, they were nearly identical to those for discrimination of AM from QFM noise, suggesting that listeners were using amplitude modulation cues in both cases.
An Experimental Study of the Kinematics of Flow Through Hoppers
Authors: Lee Jannan , Cowin S. C. , Templeton J. S.
Published: July 2002

An experimental study of the kinematics of the gravity flow of granular materials through hoppers is presented. A radiographic technique was employed to determine simultaneously the velocity and porosity fields in a granular material flowing through a model hopper. It was found that the flow of granular materials through hoppers is characterized by regions of rigid body motion interspersed with narrow bands of drastic change in void ratio and velocity. A major conclusion of this study is that the kinematic assumptions employed in previous theoretical analyses of granular materials flowing through hoppers or in converging channels are not consistent with the salient kinematic phenomena observed. Knowledge of the kinematic phenomena detailed here is basic to the proper analysis and design of hoppers.
Comparison of constitutive equations for polymer solutions in uniaxial extension
Authors: Tirtaatmadja V. , Sridhar T.
Published: July 2002

The Oldroyd-B, Giesekus, FENE-P, and White–Metzner models are used to predict the uniaxial extensional stress growth results of two ideal elastic fluids and a shear-thinning fluid. The model predictions are compared with the data obtained, at constant deformation rates, using the filament stretching technique. The linear viscoelastic parameters for the models were obtained by fitting the Oldroyd-B equations to the dynamic data. For the Giesekus and FENE-P models, the extra nonlinear parameters were obtained by fitting the model predictions to the steady shear data. The parameters for the White–Metzner model (using Carreau-type equation) were also obtained by directly fitting the steady shear data. For the ideal elastic fluids, Oldroyd-B, Giesekus, and FENE-P models with multiple modes of relaxation times generally provide good predictions of the extensional stress growth at small strain, but not particularly well at high strain. While the Oldroyd-B model predicts infinite extensional viscosity at finite extension rates, the Giesekus and FENE-P models predict steady extensional viscosities which are of the correct order of magnitude. The FENE-P equation also shows a more abrupt approach to steady state, similar to that observed experimentally. For the shear-thinning fluid the Giesekus and FENE-P models fail to predict the large stresses found in extensional flow. On the other hand, the White–Metzner model, while unable to predict the extensional stress growth for the ideal elastic fluids, is an improvement over the Oldroyd-B model for the shear-thinning fluid.
Effects of nonuniform electric field on slit flow of an electrorheological fluid
Authors: Abu-Jdayil Basim , Brunn Peter O.
Published: July 2002

In this work, slit flow of an electrorheological (ER) fluid is studied via laser Doppler anemometry under nonuniform electric-field conditions. For that purpose, the electrodes were coated with a PVC foil. Under ac conditions the ER effect with homogeneous coating was smaller than in the case of no coating. Yet, as soon as holes were punched in the foil, the ER effect greatly increased, exceeding the effect of the uncoated electrodes. Irrespective of the type of coating applied, the electric current remained the same. This contrasts with the results under dc conditions where (i) the ER effect with coating (irrespective of the type of coating) was smaller (or even zero) than without coating and where (ii) a decrease of the ER effect always was accompanied by a decrease in electric current. No electric current implied no ER effect, irrespective of the strength of the applied electric field.
On the nonlinear rheology of a wormlike micellar system in the presence of sodium salicylate salt
Authors: Aït-Ali A. , Makhloufi R.
Published: July 2002

The nonlinear rheology of an aqueous wormlike micellar system made of cetyltrime–thylammonium chloride with sodium salicylate is studied in this work. At high NaCl salt concentration the rheological measurements show a Maxwell behavior for all the solutions. The data of these samples are analyzed with respect to the Spenley, Cates, and McLeish model. The dimensionless quantities σplateau/G0 and γ̇cτR, which characterize the nonlinear rheology are compared to the predictions of this model. At a fixed surfactant concentration these quantities are found to be insensitive to changes in salt concentration and in temperature, respectively. The experimental value of the ratio σplateau/G0 we find is close at hand to the theoretical one. A discrepancy between the theory and the experiments occurs, however, in comparing the Weissenberg number defined by the product γ̇cτR.
Optical behavior of an associating polymer under shear flow
Authors: Le Meins J.-F. , Tassin J.-F. , Corpart J.-M.
Published: July 2002

Flow birefringence and dichroism experiments are used to study the behavior of solutions of a hydrophobic ethoxylated urethane with a molecular weight of 35 000 g/mol and a C16 hydrophobic end cap in a concentration range around C*. Relaxation experiments after step shear have shown the existence of two relaxation processes. The first relaxation process with a characteristic time, τshort≈0.1 s, independent of concentration, has been attributed to the lifetime of an end group in a micelle and subsequent relaxation through a Rouse process. The second relaxation process (τlong≈300 s), has been attributed to the relaxation of aggregates of polyoxyethylene chains. They induce a small dichroism in the solutions and damped oscillations in start-up shear flows at low-shear rates. Upon cessation of steady-shear flow, the two relaxations are still observed, the amplitude of the short time one increasing with shear rate. The origin of this long-time relaxation, which is not observed in classical rheological measurements, is attributed to the presence of organic impurities remaining from the chemical modification of the polymer. Extensive purification of the polymer leads to the disappearance of these impurities and consequently of the long relaxation process.
X-ray powder diffraction of RE6UO12 (RE=Eu, Gd, and Dy)
Authors: Jena Hrudananda , Asuvathraman R. , Krishnaiah M. V. , Kutty K. V. Govindan
Published: July 2002

Powder X-ray diffraction data are reported for RE6UO12 (RE=Eu, Gd, and Dy). The powders were prepared by a solution combustion method using urea as fuel. All compositions exhibit a rhombohedral structure with hexagonal unit cell parameters of a=1.012 67 (9) nm, c=0.9601 (1) nm for Eu6UO12; a=1.008 78 (6) nm, c=0.954 24 (7) nm for Gd6UO12; and a=0.998 06 (7) nm, c=0.944 03 (8) nm for Dy6UO12. The diffraction patterns of all the compounds are indexed on the R3¯ space group with Z=3. The a and c values decrease with increasing atomic number of the rare earth ion.
Viral Shedding 1 Year Following First-Episode Genital HSV-1 Infection
Authors: Johnston Christine , Magaret Amalia , Son Hyunju , Stern Michael , Rathbun Molly , Renner Daniel , Szpara Moriah , Gunby Sarah , Ott Mariliis , Jing Lichen , Campbell Victoria L. , Huang Meei-li , Selke Stacy , Jerome Keith R. , Koelle David M. , Wald Anna
Published: October 2022

Importance

Herpes simplex virus type 1 (HSV-1) is the leading cause of first-episode genital herpes in many countries.

Objective

To inform counseling messages regarding genital HSV-1 transmission, oral and genital viral shedding patterns among persons with first-episode genital HSV-1 infection were assessed. The trajectory of the development of HSV-specific antibody and T-cell responses was also characterized.

Design, Setting, and Participants

Prospective cohort followed up for up to 2 years, with 82 participants followed up between 2013 and 2018. Participants were recruited from sexual health and primary care clinics in Seattle, Washington. Persons with laboratory-documented first-episode genital HSV-1 infection, without HIV infection or current pregnancy, were referred for enrollment.

Exposures

First-episode genital HSV-1 infection.

Main Outcomes and Measures

Genital and oral HSV-1 shedding and lesion rates at 2 months, 11 months, and up to 2 years after initial genital HSV-1 infection. Participants self-collected oral and genital swabs for HSV polymerase chain reaction testing for 30 days at 2 and 11 months and up to 2 years after diagnosis of genital HSV-1. Blood samples were collected at serial time points to assess immune responses to HSV-1. Primary HSV-1 infection was defined as absent HSV antibody at baseline or evolving antibody profile using the University of Washington HSV Western Blot. HSV-specific T-cell responses were detected using interferon γ enzyme-linked immunospot.

Results

Among the 82 participants, the median (range) age was 26 (16-64) years, 54 (65.9%) were women, and 42 (51.2%) had primary HSV-1 infection. At 2 months, HSV-1 was detected from the genital tract in 53 participants (64.6%) and in the mouth in 24 participants (29.3%). Genital HSV-1 shedding was detected on 275 of 2264 days (12.1%) at 2 months and declined significantly to 122 of 1719 days (7.1%) at 11 months (model-predicted rate, 6.2% [95% CI, 4.3%-8.9%] at 2 months vs 3.2% [95% CI, 1.8%-5.7%] at 11 months; relative risk, 0.52 [95% CI, 0.29-0.93]). Genital lesions were rare, reported on 65 of 2497 days (2.6%) at 2 months and 72 of 1872 days (3.8%) at 11 months. Oral HSV-1 shedding was detected on 88 of 2247 days (3.9%) at 2 months. Persons with primary HSV-1 infection had a higher risk of genital shedding compared with those with nonprimary infection (model-predicted rate, 7.9% [95% CI, 5.4%-11.7%] vs 2.9% [95% CI, 1.7%-5.0%]; relative risk, 2.75 [95% CI, 1.40-5.44]). Polyfunctional HSV-specific CD4+ and CD8+ T-cell responses were maintained during the follow-up period.

Conclusions and Relevance

Genital HSV-1 shedding was frequent after first-episode genital HSV-1, particularly among those with primary infection, and declined rapidly during the first year after infection.
Structural biology of DOCK‐family guanine nucleotide exchange factors
Authors: Boland Andreas , Côté Jean‐Francois , Barford David
Published: October 2022

DOCK proteins are a family of multi‐domain guanine nucleotide exchange factors (GEFs) that activate the RHO GTPases CDC42 and RAC1, thereby regulating several RHO GTPase‐dependent cellular processes. DOCK proteins are characterized by the catalytic DHR2 domain (DOCKDHR2), and a phosphatidylinositol(3,4,5)P3‐binding DHR1 domain (DOCKDHR1) that targets DOCK proteins to plasma membranes. DOCK‐family GEFs are divided into four subfamilies (A to D) differing in their specificities for CDC42 and RAC1, and the composition of accessory signalling domains. Additionally, the DOCK‐A and DOCK‐B subfamilies are constitutively associated with ELMO proteins that auto‐inhibit DOCK GEF activity. We review structural studies that have provided mechanistic insights into DOCK‐protein functions. These studies revealed how a conserved nucleotide sensor in DOCKDHR2 catalyses nucleotide exchange, the basis for how different DOCK proteins activate specifically CDC42 and RAC1, and sometimes both, and how up‐stream regulators relieve the ELMO‐mediated auto‐inhibition. We conclude by presenting a model for full‐length DOCK9 of the DOCK‐D subfamily. The involvement of DOCK GEFs in a range of diseases highlights the importance of gaining structural insights into these proteins to better understand and specifically target them.
Gene signature predicting recurrence in oral squamous cell carcinoma is characterized by increased oxidative phosphorylation
Authors: Noh Joo Kyung , Woo Seon Rang , Kong Moonkyoo , Lee Min Kyeong , Lee Jung Woo , Lee Young Chan , Ko Seong‐Gyu , Eun Young‐Gyu
Published: October 2022

Although numerous studies have used systemic approaches to identify prognostic predictors in oral squamous cell carcinoma (OSCC), the effectiveness of these approaches has not been assessed clinically. Further, the mechanism underlying malignant behaviors in OSCC is poorly characterized. This study aimed to develop and verify accurate prognostic predictors for OSCC patients and assess the associated biology. We identified an OSCC‐recurrence‐related gene signature (ORGS) using a Cox regression analysis. Functional enrichment analysis was used to identify enriched pathways and biological processes to reveal the underlying mechanism of OSCC malignant behavior. The ORGS successfully divided OSCC patients into low‐ and high‐risk groups with significantly different overall survivals. Pathway analysis revealed oxidative phosphorylation (OXPHOS) as a signaling pathway associated with the ORGS in OSCC. Interestingly, high OXPHOS status was strongly associated with poor overall survival in OSCC patients. Mediator complex subunit 30 (MED30) was a predicted upstream regulator of OXPHOS, and knockdown of MED30 reduced histone acetylation. We identified that the ORGS was strongly correlated with OXPHOS regulatory processes, suggesting OXPHOS as a key mechanism leading to poor prognosis in OSCC.
Transcriptional dynamics of granulocytes in direct response to incubation with SARS‐CoV‐2
Authors: Nakazawa Daigo , Takeda Yohei , Kanda Masatoshi , Tomaru Utano , Ogawa Haruko , Kudo Takashi , Shiratori‐Aso Satoka , Watanabe‐Kusunoki Kanako , Ueda Yusho , Miyoshi Atsuko , Hattanda Fumihiko , Nishio Saori , Uozumi Ryo , Ishizu Akihiro , Atsumi Tatsuya
Published: October 2022

Severe coronavirus disease 2019 (COVID‐19) is characterized by acute respiratory distress syndrome and multiple organ dysfunction, in which the host immune response plays a pivotal role. Excessive neutrophil activation and subsequent superfluity of neutrophil extracellular traps (NETs) can lead to tissue damage, and several studies have shown the involvement of neutrophils in severe COVID‐19. However, the detailed responses of each neutrophil subset to SARS‐CoV‐2 infection has not been fully described. To explore this issue, we incubated normal‐density granulocytes (NDGs) and low‐density granulocytes (LDGs) with different viral titers of SARS‐CoV‐2. NDGs form NETs with chromatin fibers in response to SARS‐CoV‐2, whereas LDGs incubated with SARS‐CoV‐2 display a distinct morphology with condensed nuclei and moderate transcriptional changes. Based on these transcriptional changes, we suggest that AGO2 possibly plays a role in LDG regulation in response to SARS‐CoV‐2.
Depressive symptoms and conspiracy beliefs
Authors: Green Jon , Druckman James N. , Baum Matthew A. , Lazer David , Ognyanova Katherine , Perlis Roy H.
Published: October 2022

Conspiratorial beliefs can endanger individuals and societies by increasing the likelihood of harmful behaviors such as the flouting of public health guidelines. While scholars have identified various correlates of conspiracy beliefs, one factor that has received scant attention is depressive symptoms. We use three large surveys to explore the connection between depression and conspiracy beliefs. We find a consistent association, with the extent of the relationship depending on individual and situational factors. Interestingly, those from relatively advantaged demographic groups (i.e., White, male, high income, educated) exhibit a stronger relationship between depression and conspiracy beliefs than those not from such groups. Furthermore, situational variables that ostensibly increase stress—such as having COVID‐19 or parenting during COVID‐19—exacerbate the relationship while those that seem to decrease stress, such as social support, vitiate it. The results provide insight about the development of targeted interventions and accentuate the need for theorizing about the mechanisms that lead depression to correlate with conspiracy beliefs.
Eco‐Sustainable Approaches in Bone Tissue Engineering: Evaluating the Angiogenic Potential of Different Poly(3‐Hydroxybutyrate‐Co‐3‐Hydroxyhexanoate)–Nanocellulose Composites with the Chorioallantoic Membrane Assay
Authors: Stanzani Virginia , Giubilini Alberto , Checchi Marta , Bondioli Federica , Messori Massimo , Palumbo Carla
Published: October 2022

Additive manufacturing (AM) has opened new frontiers in precision medicine, giving the possibility of fabricating patient‐customized scaffolds to replace damaged tissues. In particular, bone tissue engineering (BTE) has benefited the most from the introduction of AM. In contrast, the impelling environmental issues are moving all the industrial sectors toward a sustainable development, avoiding the use of nonrenewable resources. Since thermoplastic polymers, such as poly(lactic acid) (PLA) and polycaprolactone (PCL), are massively used in the biomedical field, the primary objective of this study is to encourage the use of biodegradable and compostable materials also in BTE. Focusing on poly(3‐hydroxybutyrate‐co‐3‐hydroxyhexanoate) (PHBH), an eco‐friendly material with good biocompatibility and biodegradability, reinforced with cellulose nanocrystals (CNCs), 3D‐printed scaffolds through fused filament fabrication (FFF) are realized. Since vascularization is mandatory for bone regeneration processes and for a successful scaffold integration, the angiogenic potential of different PHBH–CNC formulations in vitro is tested, evaluating the colonization of the scaffolds by endothelial cells, and in ovo with the chorioallantoic membrane (CAM) assay. The final goal is to define the best geometry of the scaffold and PHBH–CNC composition that can trigger vascularization in BTE applications, with the ultimate aim of giving greater guarantees of osseointegration.
Highly Efficient Photodynamic Therapy with Mitochondria‐Targeting Aggregation‐Induced Emission Photosensitizer for Retinoblastoma
Authors: Zhou Lingbo , Chen Luojia , Chen Sijie , Pu Zeyuan , Gu Meijia , Shen Yin
Published: October 2022

Retinoblastoma (RB) is an aggressive eye cancer in infancy and childhood, lethal by metastasis if left untreated. Currently, the survival rate and the chance of saving vision depend on the severity of the disease. In this work, a highly efficient photodynamic ophthalmic therapy for RB is reported by employing an isoquinolinium‐based aggregation‐induced‐emission (AIE) photosensitizer (PS) TPE‐IQ‐2O for photodynamic inactivation (PDI). TPE‐IQ‐2O is an efficient mitochondria‐targeting photosensitizer as an efficient guided photodynamic therapy (PDT) agent against cancer cells. Maximizing cancer‐selectively damage to tumors with minimized side effects on normal tissue is essential for effective anticancer PDT and provides long‐lasting protection against metastasis. In addition, TPE‐IQ‐2O can effectively reduce the degree of tissue inflammation by inhibiting the expression of related inflammatory factors. TPE‐IQ‐2O also exhibits excellent biocompatibility with a neglectable hemolysis effect on mouse red blood cells and almost no killing effect on mammalian cells, which enables its potential applications in the treatment of RB.