bluuebunny/crossref_metadata_2025 huggingface dataset:
miRNPs: a novel class of ribonucleoproteins containing numerous microRNAs
Authors: Mourelatos Zissimos , Dostie Josée , Paushkin Sergey , Sharma Anup , Charroux Bernard , Abel Linda , Rappsilber Juri , Mann Matthias , Dreyfuss Gideon
Published: July 2002

Gemin3 is a DEAD-box RNA helicase that binds to the Survival of Motor Neurons (SMN) protein and is a component of the SMN complex, which also comprises SMN, Gemin2, Gemin4, Gemin5, and Gemin6. Reduction in SMN protein results in Spinal muscular atrophy (SMA), a common neurodegenerative disease. The SMN complex has critical functions in the assembly/restructuring of diverse ribonucleoprotein (RNP) complexes. Here we report that Gemin3 and Gemin4 are also in a separate complex that contains eIF2C2, a member of the Argonaute protein family. This novel complex is a large ∼15S RNP that contains numerous microRNAs (miRNAs). We describe 40 miRNAs, a few of which are identical to recently described human miRNAs, a class of small endogenous RNAs. The genomic sequences predict that miRNAs are likely to be derived from larger precursors that have the capacity to form stem–loop structures.
Crystal structure of Staphylococcus aureus tyrosyl‐tRNA synthetase in complex with a class of potent and specific inhibitors
Authors: Qiu Xiayang , Janson Cheryl A. , Smith Ward W. , Green Susan M. , McDevitt Patrick , Johanson Kyung , Carter Paul , Hibbs Martin , Lewis Ceri , Chalker Alison , Fosberry Andrew , Lalonde Judith , Berge John , Brown Pamela , Houge‐Frydrych Catherine S.V. , Jarvest Richard L.
Published: July 2002

SB‐219383 and its analogues are a class of potent and specific inhibitors of bacterial tyrosyl‐tRNA synthetases. Crystal structures of these inhibitors have been solved in complex with the tyrosyl‐tRNA synthetase from Staphylococcus aureus, the bacterium that is largely responsible for hospital‐acquired infections. The full‐length enzyme yielded crystals that diffracted to 2.8 Å resolution, but a truncated version of the enzyme allowed the resolution to be extended to 2.2 Å. These inhibitors not only occupy the known substrate binding sites in unique ways, but also reveal a butyl binding pocket. It was reported that the Bacillus stearothermophilus TyrRS T51P mutant has much increased catalytic activity. The S. aureus enzyme happens to have a proline at position 51. Therefore, our structures may contribute to the understanding of the catalytic mechanism and provide the structural basis for designing novel antimicrobial agents.
Lack of synergy for inhibitors targeting a multi‐drug‐resistant HIV‐1 protease
Authors: King Nancy M. , Melnick Laurence , Prabu‐Jeyabalan Moses , Nalivaika Ellen A. , Yang Shiow‐Shong , Gao Yun , Nie Xiaoyi , Zepp Charles , Heefner Donald L. , Schiffer Celia A.
Published: July 2002

The three‐dimensional structures of indinavir and three newly synthesized indinavir analogs in complex with a multi‐drug‐resistant variant (L63P, V82T, I84V) of HIV‐1 protease were determined to ∼2.2 Åresolution. Two of the three analogs have only a single modification of indinavir, and their binding affinities to the variant HIV‐1 protease are enhanced over that of indinavir. However, when both modifications were combined into a single compound, the binding affinity to the protease variant was reduced. On close examination, the structural rearrangements in the protease that occur in the tightest binding inhibitor complex are mutually exclusive with the structural rearrangements seen in the second tightest inhibitor complex. This occurs as adaptations in the S1 pocket of one monomer propagate through the dimer and affect the conformation of the S1 loop near P81 of the other monomer. Therefore, structural rearrangements that occur within the protease when it binds to an inhibitor with a single modification must be accounted for in the design of inhibitors with multiple modifications. This consideration is necessary to develop inhibitors that bind sufficiently tightly to drug‐resistant variants of HIV‐1 protease to potentially become the next generation of therapeutic agents.
Myocardial blood flow quantification with MRI by model‐independent deconvolution
Authors: Jerosch‐Herold Michael , Swingen Cory , Seethamraju Ravi Teja
Published: July 2002

Magnetic resonance (MR) imaging during the first pass of an injected contrast agent has been used to assess myocardial perfusion, but the quantification of blood flow has been generally judged as too complex for its clinical application. This study demonstrates the feasibility of applying model‐independent deconvolution to the measured tissue residue curves to quantify myocardial perfusion. Model‐independent approaches only require minimal user interaction or expertise in modeling. Monte Carlo simulations were performed with contrast‐to‐noise ratios typical of MR myocardial perfusion studies to determine the accuracy of the resulting blood flow estimates. With a B‐spline representation of the tissue impulse response and Tikhonov regularization, the bias of blood flow estimates obtained by model‐independent deconvolution was less than 1% in all cases for peak contrast to noise ratios in the range from 15:1 to 20:1. The relative dispersion of blood flow estimates in Monte Carlo simulations was less than 7%. Comparison of MR blood flow estimates against measurements with radio‐isotope labeled microspheres indicated excellent linear correlation slope: 0.96, intercept: 0.06). It can be concluded from these studies that the application of myocardial blood flow quantification with MRI can be performed with model‐independent methods, and this should support a more widespread use of blood flow quantification in the clinical environment.
Tissue ablation using an acoustic waveguide for high‐intensity focused ultrasound
Authors: Sommer F. Graham , Sumanaweera Thilaka S. , Glover Gary
Published: July 2002

High‐intensity focused ultrasound (HIFU) has been shown capable of selective tissue destruction in humans, with promise as a tool for ablation of tumors, although one practical problem is reflection of sound at gas or bony interfaces within the body. We evaluated a water‐filled cylindrical metal tube as a waveguide for HIFU, since such a general technique might be useful for ablation of otherwise inaccessible tumors in the body. Our studies indicate that such a waveguide is capable of propagating HIFU from a piezoelectric source, with resultant heating of tissue specimens to greater than 80 °C, causing focal tissue destruction.
A proposal for a standard electronic anthropomorphic phantom for radiotherapy
Authors: Aldridge J. S. , Reckwerdt P. J. , Mackie T. R.
Published: July 2002

To create a database of human male and female computed tomography (CT) slices, the National Library of Medicine organized the “Visible Human Project.” Since the male and female data sets provided are approximately 269 MB and 915 MB, respectively, both the size and complexity have been reduced. While making the slices accessible to those with limited computing resources, the production of these reduced data sets also presents a unique opportunity to establish a standard human CT slice library for research in radiation therapy. A brief history of the original data sets is included, as well as details of the reduction process, applications to radiotherapy, and information on accessing these reduced image files.
An analysis of Freedman’s “image pulse” model in air
Authors: Tsakiris Janos , McKerrow Phillip
Published: July 2002

The “image pulse” model developed by Freedman calculates the echoes generated from convex objects in an underwater environment after insonification with a narrow-band transient signal. The model uses the source radiation and the solid angle subtended at the transducer by the scattering body to determine the echo structure. Work has been completed in adapting this model for use in an air environment using noncoincident transmitters and receivers. Experiments were conducted to measure the amplitudes of the echoes off a range of convex objects, at distances up to 1.4 m, after insonification with a Polaroid transducer. These measured amplitudes were compared to those predicted by the model, with the results for cones highlighting the limitations of the model. Spheres, however, performed significantly better, with an average error of under 5%, indicating that the model should be reasonably accurate at calculating the echoes off convex objects with a smoothly varying surface.
Effective impedance of rough porous ground surfaces
Authors: Attenborough Keith , Waters-Fuller Tim
Published: July 2002

Laboratory measurements at grazing angles of the impedance of sand surfaces containing artificial two-dimensional (2D) roughness are compared with predictions of an extended boss theory, which allows for incoherent scatter, randomness, and finite impedance effects. The data and predictions are found to be in reasonable agreement. The rough surface impedance model may be used, as an alternative to layering, to explain measurements where the reactance exceeds the resistance at low frequencies. The model also explains instances where the measured ground impedance tends to zero at higher frequencies. In addition, the model is found to predict features of measurements made with an elevated source and vertically separated receivers at a range of 30 m over cultivated ground surfaces.
Measuring vocal quality with speech synthesis
Authors: Gerratt Bruce R. , Kreiman Jody
Published: July 2002

Much previous research has demonstrated that listeners do not agree well when using traditional rating scales to measure pathological voice quality. Although these findings may indicate that listeners are inherently unable to agree in their perception of such complex auditory stimuli, another explanation implicates the particular measurement method—rating scale judgments—as the culprit. An alternative method of assessing quality—listener-mediated analysis-synthesis—was devised to assess this possibility. In this new approach, listeners explicitly compare synthetic and natural voice samples, and adjust speech synthesizer parameters to create auditory matches to voice stimuli. This method is designed to replace unstable internal standards for qualities like breathiness and roughness with externally presented stimuli, to overcome major hypothetical sources of disagreement in rating scale judgments. In a preliminary test of the reliability of this method, listeners were asked to adjust the signal-to-noise ratio for 12 synthetic pathological voices so that the resulting stimuli matched the natural target voices as well as possible For comparison to the synthesis judgments, listeners also judged the noisiness of the natural stimuli in a separate task using a traditional visual-analog rating scale. For 9 of the 12 voices, agreement among listeners was significantly (and substantially) greater for the synthesis task than for the rating scale task. Response variances for the two tasks did not differ for the remaining three voices. However, a second experiment showed that the synthesis settings that listeners selected for these three voices were within a difference limen, and therefore observed differences were perceptually insignificant. These results indicate that listeners can in fact agree in their perceptual assessments of voice quality, and that analysis-synthesis can measure perception reliably.
Analysis and measurement of a matched volume velocity sensor and uniform force actuator for active structural acoustic control
Authors: Gardonio P. , Lee Y.-S. , Elliott S. J. , Debost S.
Published: July 2002

This paper presents a theoretical and experimental study of the frequency response function of a matched volume velocity sensor and uniform force actuator for active structural acoustic control. The paper first reviews the design of a volume velocity sensor and uniform force actuator on a panel, using piezoelectric film with quadratic shaping of the electrodes. The frequency response function of a matched volume velocity sensor and uniform force actuator bonded on either sides of a panel is then studied in detail. This analysis shows that below 100 Hz the sensor–actuator response is controlled by the bending vibration of the panel and a good estimate of the volumetric component of the transverse vibration of the panel is achieved. At higher frequencies, however, the sensor–actuator response is controlled by the in-plane longitudinal and shear vibration of the panel, which causes the real part of the frequency response function to be not strictly positive and to be characterized by large amplitudes at higher frequencies. These two phenomena are important since they limit the possibility of implementing a stable direct velocity feedback control system using these transducers.
Neural activity associated with distinguishing concurrent auditory objects
Authors: Alain Claude , Schuler Benjamin M. , McDonald Kelly L.
Published: July 2002

The neural processes underlying concurrent sound segregation were examined by using event-related brain potentials. Participants were presented with complex sounds comprised of multiple harmonics, one of which could be mistuned so that it was no longer an integer multiple of the fundamental. In separate blocks of trials, short-, middle-, and long-duration sounds were presented and participants indicated whether they heard one sound (i.e., buzz) or two sounds (i.e., buzz plus another sound with a pure-tone quality). The auditory stimuli were also presented while participants watched a silent movie in order to evaluate the extent to which the mistuned harmonic could be automatically detected. The perception of the mistuned harmonic as a separate sound was associated with a biphasic negative–positive potential that peaked at about 150 and 350 ms after sound onset, respectively. Long duration sounds also elicited a sustained potential that was greater in amplitude when the mistuned harmonic was perceptually segregated from the complex sound. The early negative wave, referred to as the object-related negativity (ORN), was present during both active and passive listening, whereas the positive wave and the mistuning-related changes in sustained potentials were present only when participants attended to the stimuli. These results are consistent with a two-stage model of auditory scene analysis in which the acoustic wave is automatically decomposed into perceptual groups that can be identified by higher executive functions. The ORN and the positive waves were little affected by sound duration, indicating that concurrent sound segregation depends on transient neural responses elicited by the discrepancy between the mistuned harmonic and the harmonic frequency expected based on the fundamental frequency of the incoming stimulus.
Bottom reflection coefficient measurement and geoacoustic inversion at the continental margin near Vancouver Island with the aid of spiking filters
Authors: Heard Garry J.
Published: July 2002

This paper presents the results of an experiment to measure the reflection coefficient versus grazing angle at the continental margin west of Vancouver Island. The measured reflection coefficients are inverted and estimates of the surficial sediment geoacoustic properties obtained. The receiver used in this experiment was a long towed array with the source in aft-endfire aspect. The acoustic sources for this experiment were explosives that produced direct-path arrivals approximately 0.1 s in length. Bottom and sub-bottom arrivals continued for several seconds duration. Explosives were detonated at intervals such that bottom reflected energy received at the array sampled grazing angles in the interval 10°–80°. Source–receiver ranges were computed by measuring arrival time differences at each of the array elements, comparing these time differences with those computed using a ray-tracing propagation model, and globally minimizing the accumulated squared time difference residuals. To aid in the measurement of arrival times, spiking filters were employed to produce a deconvolution-like output that separates arrivals overlapped in the original time series. The reflection coefficient estimates were determined from the linear spiking filter outputs by forming the ratio of the direct-path and bottom-reflected arrival amplitudes. This technique is efficient and provides estimates of the surficial sediment reflection coefficient by excluding energy returned from sub-bottom layers.
Generation of zones of quiet using a virtual microphone arrangement
Authors: Garcia-Bonito J. , Elliott S. J. , Boucher C. C.
Published: July 2002

A local active noise control system is described which uses a virtual microphone arrangement. This arrangement is based on the assumption that the primary pressure at the physical and at the virtual microphone locations are similar. The implication of this assumption on the acoustic performance of a local system in a diffracted primary sound field is theoretically studied. The results show that the error at the virtual microphone position is lower when the virtual microphone arrangement is in the vicinity of a diffracting surface. A practical local active noise control system in a headrest has been built and used to measure the zone of quiet produced by a single and a dual channel system when the total pressure is canceled at one or two virtual microphone positions. It is shown that this type of arrangement is capable of projecting the zones of quiet further away from the secondary source than the position of the physical microphone. The measured zones of quiet produced by a single-channel system have been compared with the results produced with a theoretical model which includes the diffraction between two spheres, one representing the secondary source and the other the listener’s head. It has been found that, in the frequency range of applicability of a local active noise control system, the two-sphere model predicts the experimental results well. The effect that the diffracting head has on the performance of an adaptive feedforward controller using a physical and a virtual microphone is also explored and the results show that this effect is small provided the initial system identification is performed in the presence of the head.
The dynamic coupling between piezoceramic actuators and a beam
Authors: Brennan M. J. , Elliott S. J. , Pinnington R. J.
Published: July 2002

This paper describes the coupling between piezoceramic actuators and flexural and longitudinal vibration of a beam. A comprehensive model, which incorporates the mass and stiffness of the actuator elements, is used to couple the actuators to a beam using the wave approach. Experimental results are presented, and it is shown that at high frequencies it is necessary to consider the dynamic loading of the actuator to accurately model the characteristics of the flexural vibration actuator. For the longitudinal actuator, however, it is shown that it is acceptable to neglect the dynamic loading of the actuator. The way in which the actuator affects the passive behavior of the beam is also considered by investigating the scattering of waves by the actuator. Wave scattering by a single-element piezoceramic actuator is also investigated and is shown to be negligibly small for the practical structures generally in current use.
Noise directionality for surface sources in range-dependent environments
Authors: Harrison C. H.
Published: July 2002

An earlier paper [J. Acoust. Soc. Am. 99, 2055–2066 (1996)] tackled the calculation of ambient noise and noise coherence in a range-independent reflecting or refracting environment with horizontal distributions of noise sources. The approach was analytical producing some closed-form solutions and never more than a single well-behaved integral to solve. In this paper the azimuth and elevation dependence of the noise over a sloping bottom is investigated. The analytical and graphical results explicitly show the effects of upslope and downslope bottom reflections on the “noise notch,” and in passing they explain the flatness of the angle distribution sought by Dashen and Munk [J. Acoust. Soc. Am. 76, 540–554 (1984)]. It is also clear that, contrary to one’s intuition, three-dimensional horizontal bending effects on the noise directionality may be significant because of the large contribution from distant sources.
Tracking and localizing a moving source in an uncertain shallow water environment
Authors: Tantum Stacy L. , Nolte Loren W.
Published: July 2002

An optimal approach to tracking a moving source in the presence of environmental variability is presented. This tracking algorithm, called the optimum uncertain field tracking algorithm (OUFTA), incorporates a model for the source motion as well as the uncertain ocean environment. The performance of the OUFTA is evaluated over a range of signal-to-noise ratios (SNRs) as a function of the number of observations by examining its ability to correctly estimate both the current source position and the entire source track. The improvement in performance provided by the OUFTA is illustrated by comparison to two suboptimal tracking algorithms. Results show that incorporating a priori knowledge of both the source dynamics and the ocean model provides the most accurate estimates of the source track.
“How to milk a coat:” The effects of semantic and acoustic information on phoneme categorization
Authors: Borsky Susan , Tuller Betty , Shapiro Lewis P.
Published: July 2002

This study examined the effect of sentence context and local acoustic structure on phoneme categorization. Target stimuli from a 10-step GOAT–COAT continuum, differing only on a temporal cue for voice onset time (VOT), were embedded in carrier sentences that biased interpretation toward either “goat” or “coat.” While subjects listened to the sentences they also responded as quickly as possible to a visual probe by indicating whether the probe matched the target stimulus they heard. Results showed that the interaction of VOT and sentence context significantly affected both identification and RT for stimuli near the perceptual boundary; the identification function showed a boundary shift in favor of the biased context and peak response times for each context reflected the shifted identification boundaries. In addition, response times were faster for identification of stimuli near the category boundary when responses were congruent, rather than incongruent with the sentence context. The response time differences for congruent versus incongruent responses in the boundary region are interpreted as depending on the results of initial phonological analysis; potentially ambiguous categorizations may be subject to additional evaluation in which a context-congruent response is both preferred and available earlier.
Voice F0 responses to manipulations in pitch feedback
Authors: Burnett Theresa A. , Freedland Marcia B. , Larson Charles R. , Hain Timothy C.
Published: July 2002

Recent studies have shown that when phonating subjects hear their voice pitch feedback shift upward or downward, they respond with a change in voice fundamental frequency (F0) output. Three experiments were performed to improve our understanding of this response and to explore the effects of different stimulus variables on voice F0 responses to pitch-shift stimuli. In experiment 1, it was found that neither the absolute level of feedback intensity nor the presence of pink masking noise significantly affect magnitude or latency of the voice F0 response. In experiment 2, changes in stimulus magnitude led to no systematic differences in response magnitudes or latencies. However, as stimulus magnitude was increased from 25 to 300 cents, the proportion of responses that changed in the direction opposite that of the stimulus (“opposing” response) decreased. A corresponding increase was observed in the proportion of same direction responses (“following” response). In experiment 3, increases in pitch-shift stimulus durations from 20 to 100 ms led to no differences in the F0 response. Durations between 100 and 500 ms led to longer duration voice F0 responses with greater response magnitude, and suggested the existence of a second F0 response with a longer latency than the first.
Characterizing the clarinet tone: Measurements of Lyapunov exponents, correlation dimension, and unsteadiness
Authors: Wilson Teresa D. , Keefe Douglas H.
Published: July 2002

The clarinet tone is produced by a self-sustained oscillation involving nonlinearity between the flow through the reed and the mechanical response of the reed, and acoustic coupling via the air column response. Regimes of oscillation include periodic, biperiodic, and other quasi-periodic signals, yet even a nominally periodic tone has small, but perceptually and musically important, deviations that are obscured in a conventional power spectrum. Such deviations may be due to the nonlinear dynamics underlying sound production or to perturbations in the performer’s control of the instrument via changes in lip embouchure, blowing pressure, and vocal tract configuration. Techniques based upon experimental nonlinear dynamics and short-time signal processing are applied to the acoustic signal measured within the clarinet mouthpiece to assess the role of these additional deviations on sound production. These include the Lyapunov exponent, correlation dimension, and a normalized period-synchronous energy variance, termed unsteadiness. Normal tones and multiphonics are indistinguishable with respect to their Lyapunov exponents. The largest exponent is small and positive, indicating a small amount of information loss each cycle. The information in clarinet tones diminishes at rates ranging from 10 to 60 bits/s. Unsteadiness accounts for the variations in correlation dimension for normal tones but not for multiphonics. These measures may be useful in the study of more subtle aspects of tone production in wind instruments.
A microcosm of musical expression. I. Quantitative analysis of pianists’ timing in the initial measures of Chopin’s Etude in E major
Authors: Repp Bruno H.
Published: July 2002

Patterns of expressive timing were measured in bars 1–5 of 115 commercially recorded performances of Chopin’s Etude in E major, op. 10, No. 3. These patterns were subjected to principal components analysis, which suggested at least four independent “timing strategies”: (1) major ritards at the ends of melodic gestures; (2) acceleration within some of these gestures, without final ritards; (3) extreme lengthening of the initial downbeat; and (4) ritards between as well as within melodic gestures. Strategies 1 and 4 respond in different ways to the melodic-rhythmic grouping structure of the music, and strategy 3 merely represents a local emphasis. Strategy 2 is the one most difficult to rationalize; it does not seem to represent an alternative structural interpretation of the music but rather an alternative gestural shaping. Each individual pianist’s timing pattern could be described as a weighted combination of these four strategies plus idiosyncratic variation. A wide variety of combinations was represented, and no two individual patterns were exactly the same. In addition, there was a wide range of basic tempi and of degrees of tempo modulation. There were no strong relationships between any of these variables and sociocultural characteristics of the artists, although some weak trends were observed.
Radiation modal expansion: Application to active structural acoustic control
Authors: Gibbs Gary P. , Clark Robert L. , Cox David E. , Vipperman Jeffrey S.
Published: July 2002

This paper demonstrates active structural acoustic control using multiple input/output adaptive sensoriactuators combined with radiation filters and a feedback control paradigm. A new method of reduced order modeling/design of radiation filters termed radiation modal expansion (RME) is presented. For the experiments detailed in this paper, the RME technique reduced the modeling of the radiation matrix from 400 transfer functions to 6 transfer functions (multiplied by a constant transformation matrix). Experimental results demonstrate reductions of radiated sound power on the order of 5 dB over the bandwidth of 0–800 Hz.
Analysis and synthesis of intonation using the Tilt model
Authors: Taylor Paul
Published: July 2002

This paper introduces the Tilt intonational model and describes how this model can be used to automatically analyze and synthesize intonation. In the model, intonation is represented as a linear sequence of events, which can be pitch accents or boundary tones. Each event is characterized by continuous parameters representing amplitude, duration, and tilt (a measure of the shape of the event). The paper describes an event detector, in effect an intonational recognition system, which produces a transcription of an utterance’s intonation. The features and parameters of the event detector are discussed and performance figures are shown on a variety of read and spontaneous speaker independent conversational speech databases. Given the event locations, algorithms are described which produce an automatic analysis of each event in terms of the Tilt parameters. Synthesis algorithms are also presented which generate F0 contours from Tilt representations. The accuracy of these is shown by comparing synthetic F0 contours to real F0 contours. The paper concludes with an extensive discussion on linguistic representations of intonation and gives evidence that the Tilt model goes a long way to satisfying the desired goals of such a representation in that it has the right number of degrees of freedom to be able to describe and synthesize intonation accurately.
Active control of harmonic sound transmission into an acoustic enclosure using both structural and acoustic actuators
Authors: Kim Sang-Myeong , Brennan Michael J.
Published: July 2002

This paper describes an analytical and experimental investigation into the active control of harmonic sound transmission in a structural–acoustic coupled system. A rectangular enclosure is considered that has five acoustically rigid walls and a flexible plate on the remaining side through which a harmonic sound wave is transmitted into the enclosure. The control system is designed to globally reduce the sound field inside the enclosure, and the roles of structural and acoustic actuators are of particular interest. Three control configurations, classified by the type of actuators, are compared and discussed. They are: (i) use of a single point-force actuator, (ii) use of a single acoustic piston source, and (iii) simultaneous use of both a point-force actuator and an acoustic piston source. It is shown both analytically and experimentally that the point-force actuator is effective in controlling plate-dominated modes while the acoustic source is effective in controlling cavity-dominated modes. Since the transmitted sound field is governed by both plate- and cavity-dominated modes, the hybrid use of both types of actuators is shown to be a desirable configuration for the active control of sound transmission into a structural–acoustic coupled system.
Combined Stress-Creep Experiments on a Nonlinear Viscoelastic Material to Determine the Kernel Functions for a Multiple Integral Representation of Creep
Authors: Onaran K. , Findley W. N.
Published: July 2002

A multiple integral functional relationship has been employed as a constitutive equation for nonlinear creep of viscoelastic material under combined stress. The kernel functions of this representation for first, second and third order stress terms have been determined from tests on a single tubular specimen of polyvinyl chloride copolymer. Tests needed to determine kernel functions adequate to describe multiaxial creep under constant stress were found to be three pure tension tests at different stress levels, three pure torsion tests at different stress levels, and two combined tension-torsion tests. Experiments include twenty tests under various combinations of tension and torsion of the same specimen. The use of only one specimen was made possible by the fact that following 2 hr of creep the recovery in 4 days was almost complete. Agreement between the multiple integral representation and experimental results was very satisfactory. Agreement with a hyperbolic sine representation of stress dependence was less satisfactory owing in part to the fact that the synergistic effect of tension plus torsion in the nonlinear range was not accounted for.
An In Vitro Investigation of Ciliated Activity
Authors: Miller C. E. , Goldfarb H.
Published: July 2002

Diseases of the respiratory tract may be related to the altered rheological properties of the respiratory tract mucus and to the altered ciliary shearing capabilities. Flow curves are presented showing that mucus has thixotropic properties and has discrete yield points. Mechanical models of cilia constructed to perform oscillatory motions comparable to those in vivo have been studied as shearing elements in a modification of the Hoppmann-Miller Rotational Fluid Flow Generator. A description of those modifications is presented with special attention being given to the design of special cams needed to carry out the proper oscillation of the simulated cilia. Flow trends and particle path lines are described for the mechanical cilia oscillating in and out of phase. Linear velocity of small particles injected into the flow is measured as a function of frequency of oscillation. Finally, some interesting questions are raised pertaining to in vivo ciliated activity in light of experience gained with the apparatus.
A Modified Superposition Principle Applied to Creep of Nonlinear Viscoelastic Material Under Abrupt Changes in State of Combined Stress
Authors: Findley W. N. , Lai J. S. Y.
Published: July 2002

A modified superposition principle has been employed to describe creep in the nonlinear range under combined stresses which change abruptly from time to time. The stress function fij employed is derived from three integrals of the multi-integral theory for constant stress. Several means of treating the nonlinearity in stress when the stress changes are investigated. The most satisfactory of these considers that after a change in stress from σkl(1) to σkl(2) the creep may be described as the sum of the recovery resulting from removal of σkl(1) and the creep from application of σkl(2), the recovery being computed on the basis of superposition. Thus for a power function of time t where the strain ε=ε0+ε+tn and n is a constant the creep following a change in stress at time t1 is given by εij(t)=fij0(σkl(1))+[fij0(σkl(2))−fij0(σkl(1))]+fij+(σkl(1))tn+[fij+(σkl(2))−fij+(σkl(1))] (t−tl)n. Experiments on an unplasticized poly(vinyl chloride) include tension creep followed by multiple-step unloading; combined tension and torsion creep followed by multiple-step unloading; combined tension and torsion creep with several abrupt changes in combination of tension and torsion; and tension creep with partial unloading and reloading. The method describes the time dependence reasonably well in all cases, but the total strain following partial unloading from high combined stresses in the nonlinear range was substantially larger than predicted.
Application of Prony Series to Linear Viscoelasticity
Authors: Soussou J. E. , Moavenzadeh F. , Gradowczyk M. H.
Published: July 2002

A new method for description of viscoelastic functions with Prony series of exponentials is presented and compared with existing methods. This method places constraints on the coefficients of the series which guarantees smoothness of the functions and a discrete spectral representation. An optimization technique is used to obtain the solution. The resulting series permit the use of Whittaker's method of solution of integral equations which is specialized to the case of viscoelastic analysis, and an exact relationship is obtained between creep and relaxation functions.
Creep of Polyurethane under Varying Temperature for Nonlinear Uniaxial Stress
Authors: Lai J. S. Y. , Findley W. N.
Published: July 2002

Two methods are described to account for varying temperature during creep. Both employ the modified superposition principle. One uses a reduced time involving a shift factor which is a function of both stress and temperature history. The other considers the strain to be a function of the current values of stress and temperature. Experiments on polyurethane include constant stress creep and recovery at several temperatures in the nonlinear range and an experiment in which the stress was held constant while the temperature increased at a constant rate, then the stress was removed and the temperature decreased at a constant rate. The strain in this experiment was predicted by means of the theories from the results of the constant temperature creep tests. The strain in the constant temperature creep and recovery tests were described by means of the multiple integral representation and the modified superposition principle. Most of the nonlinearity and temperature effect were found in the coefficient of the time-dependent term.
Stress Relaxation of Starch Xanthide Reinforced Vulcanizates
Authors: Bagley E. B. , Dixon R. E.
Published: July 2002

Stress relaxation of a reinforced vulcanized styrene-butadiene (SBR) elastomer after simple elongation has been investigated over a range of strains and at several filler levels. Carbon blacks and starch xanthide were the reinforcing agents studied. Double logarithmic plots of load versus time at constant strain were linear over five decades in time, the slope being relatively insensitive to either filler type or loading level, except at low extensions or near the ultimate elongation level. The apparent relaxation time, given as the ratio of a viscosity, η, to a modulus, E, is thus independent of filler. Ratios (ηf/ηu) and (Ef/Eu), where the subscripts f and u refer to filled and unfilled material, respectively, must show the same functional dependence on filler loading level. The usual two constant Mooney plots of [load/(λ−λ−2)] versus λ−1, where λ is the extension ratio, were highly nonlinear, rising steeply as λ−1 approached unity, particularly for starch xanthide reinforced elastomers. Modulus ratio versus volume fraction plots suggest that the rigid phase, mechanically, is the continuous phase in starch xanthide reinforced elastomers.
A Man in His 20s With Gradually Enlarging Mediastinal Mass and Intermittent Hemoptysis
Authors: Yang Ruiyi , Yu Jianqun
Published: December 2022

This case report describes a diagnosis of ruptured coronary artery aneurysm after a patient presentation of chest pain and new-onset intermittent hemoptysis.
Arcadia, Egypt
Authors: Palme Bernhard
Published: December 2022

Arcadia is the name of one of the Roman provinces located in Egypt in Late Antiquity. Created not long before 398
ce
, Arcadia's territory encompassed Middle Egypt from the top of the Nile Delta at Memphis to the border of the Thebaid near Hermopolis. Oxyrhynchos, the capital of Arcadia, and other major towns like Herakleopolis and Arsinoiton Polis are the main sites of papyrus finds. Consequently, Arcadia is among the best documented areas of the later Roman Empire. After the Arab conquest of Egypt in 640/1, Arcadia remained an administrative unit well into the eighth century.
Kingship, Hellenistic
Authors: Hannestad Lise
Published: December 2022

In the Greek world, the period from the death of Alexander (323bce) to the Roman conquest of Egypt (31bce) was characterized by the formation of a number of kingdoms. Alexander's senior officers immediately began fighting for power and land. Three large kingdoms and gradually a number of smaller ones were established that dominated the Greek world until 31bce.
Hierapytna
Authors: Guizzi Francesco
Published: December 2022

Hierapytna (modern Ierapetra) is a Cretan city that reached a considerable degree of development and territorial expansion in the second century
bce
and also flourished in Roman times. Its history is reconstructed mainly thanks to the numerous epigraphic testimonies.
Leukas (Leucas)
Authors: Bonelou Elena
Published: December 2022

Leukas (Leucas) is an island situated opposite northwestern Akarnania. Its name derives from the hero Leukadios, son of Ikarios, and the cape Leukata, at the southern part of the island. During the reign of the tyrant Kypselos, the Corinthians established a colony on the northeastern part of the island and opened the narrow channel between Leukas and Akarnania (
dioryktos
) to be navigable.
Pale
Authors: Bonelou Elena
Published: December 2022

Pale, one of the four
poleis
of Kephallenia, was situated on the western peninsula of the island called Paliki. It was named after Peleus, son of Kephalos, who was the mythical founder of the island.
Intermolecular Cross‐Linking Reinforces Polymer Binders for Durable Alloy‐Type Anode Materials of Sodium‐Ion Batteries
Authors: Yao Qian , Zhu Yansong , Zheng Cheng , Wang Nana , Wang Dongdong , Tian Fang , Bai Zhongchao , Yang Jian , Qian Yitai , Dou Shixue
Published: December 2022

Sodium‐ion batteries show promising potential for large‐scale energy storage. However, the large size and heavy mass of Na+ always results in huge volume change and inferior electrochemical stability, especially in alloy‐type anode materials. Here, molecular engineering of the polymer binders, i.e., cross‐linking of poly(acrylic acid) with glycerin (PAA‐GLY), reinforces the mechanical properties, eliminates the active protons of PAA, and benefits electrolyte diffusion, thereby remarkably improving electrochemical performance. Using µ‐Sn as an example, the cycle life at 2 A g−1 is extended from ≈26 cycles of PAA to ≈2000 cycles of PAA‐GLY. Meanwhile, the initial Coulombic efficiency is promoted to 90.3%, allowing the fabrication step of electrode presodiation for full cells to be eliminated. Thus, the full cells run 300 cycles at 2 A g−1. In addition, the binder allows the thick electrode to exhibit an areal capacity of 6.8 mAh cm−2. This binder is also applied for µ‐Bi and µ‐Sb. The simple operation, remarkable improvement, and wide applications indicate the promising prospects of this strategy for advanced electrodes in sodium ion batteries.
SHORT syndrome with microcephaly and developmental delay
Authors: Patel Viraj , Cui Wei , Cobben Jan M.
Published: December 2022

We report a boy with typical clinical features of SHORT syndrome alongside a significant microcephaly and severe developmental delay associated with a de novo single nucleotide missense DNA variant resulting in a single amino acid change in codon 486 of the PIK3R1 gene (PIK3R1 c.1456G>A (p.Ala486Thr)). Our report strikingly coincides with another recently published case from Brazil, describing a 23‐year‐old woman with the same de novo PIK3R1 DNA variant, who also exhibits SHORT syndrome with severe secondary microcephaly and intellectual disability. On review of the literature, we have identified further cases of PIK3R1‐related SHORT Syndrome with a similar phenotype. We note all these cases (including ours) have variants located in the ‐inter SH2 domain (iSH2); we speculate that pathogenic iSH2 located PIK3R1 variants are associated with a different and otherwise unreported clinical picture of SHORT syndrome that presents with microcephaly and/or significant developmental delay/intellectual disability. The pathogenic mechanism of why these variants apparently lead to a different clinical picture of SHORT syndrome remains unknown.
Large and Robust Exchange Bias in Co/CoO film: Implication for Flexible Spintronics
Authors: Sun Yuting , Tang Wei , Chen Siliang , Liu Liang , Liu Haoliang , Ge Jun‐Yi , Zhang Xi , Jiang Wei‐Chao , Liang Huawei , Zeng Yu‐Jia
Published: December 2022

Developing a robust and flexible exchange bias (EB) system is crucial for wearable spintronic devices. In this work, large and robust EB effect is demonstrated in flexible Co/CoO thin films grown by magnetron sputtering. The obtained EB field is as large as 6172 Oe at low temperatures on a flexible substrate. Based on the atomistic spin models, the unexpectedly large EB field is explained by the decrease of ferromagnetic grain size and the increase of ferromagnetic /antiferromagnetic contact area. Furthermore, the strain‐dependent coercivity and EB effect are observed in flexible Co/CoO films. Finally, the flexible Co/CoO thin film shows no degradation (even a slight increase) of performances in all figures of merit after 500 bending cycles, indicating excellent mechanical durability. This study sheds light on Co/CoO as a robust EB material for flexible spintronics.
Relatedness and compatibility: The concept of privacy in Mandarin Chinese and American English corpora
Authors: Ma Yuanye
Published: December 2022

This study investigates how privacy as an ethical concept exists in two languages: Mandarin Chinese and American English. The exploration relies on two genres of corpora from 10 years: social media posts and news articles, 2010–2019. A mixed‐methods approach combining structural topic modeling (STM) and human interpretation were used to work with the data. Findings show various privacy‐related topics across the two languages. Moreover, some of these different topics revealed fundamental incompatibilities for understanding privacy across these two languages. In other words, some of the variations of topics do not just reflect contextual differences; they reveal how the two languages value privacy in different ways that can relate back to the society's ethical tradition. This study is one of the first empirically grounded intercultural explorations of the concept of privacy. It has shown that natural language is promising to operationalize intercultural and comparative privacy research, and it provides an examination of the concept as it is understood in these two languages.
η6‐Metalated Aryl Iodides in Diels‐Alder Cycloaddition Reactions: Mode of Activation and Catalysis
Authors: Portela Susana , Fernández Israel
Published: December 2022

The potential application of η6‐metalated aryl iodides as organocatalyst has been explored by means of computational methods. It is found that the enhanced halogen bonding donor ability of these species, in comparison with their demetalated counterparts, translates into a significant acceleration of the Diels‐Alder cycloaddition reaction involving cyclohexadiene and methyl vinyl ketone. The factors behind this acceleration, theendo‐exoselectivity of the process and the influence of the nature of the transition metal fragment in the activity of these species are quantitatively explored in detail by means of the combination of the Activation Strain Model of reaction and the Energy Decomposition Analysis methods.
Understanding and Mitigating Interpersonal Communication Conflict in Field‐Based Institutions
Authors: McDermott Victoria , Kauten Rebecca , Gee Jennifer , May Amy
Published: December 2022

Interpersonal communication conflict is an inevitable part of field‐based experiences due to the many complex variables that influence human interactions, such as culture, gender, and perceived power. Moreover, in field‐based institutions (i.e., field stations and marine laboratories) privacy may be limited in terms of space and time, and physical conditions may be challenging, which can lead to more frequent and intense interpersonal conflicts. Conflicts can arise episodically or cyclically at a field‐based institution, impacting visitors and employees at all levels, that is, between students, staff, faculty, and leadership. Those who work seasonally or permanently at field‐based institutions may be able to mitigate some of the potential negative outcomes associated with unmanaged conflict by knowing when these incidents might occur, as well as how to employ meaningful conflict management strategies during these times. Thus, we propose the 10/60 model of field station experiences to define significant points of time during a field experience in which collecting feedback may be critical for avoiding communication conflict. We provide additional recommendations on best practices for soliciting feedback, as well as the importance of setting explicit communication expectations for those in leadership positions to create more inclusive and equitable spaces.