bluuebunny/crossref_metadata_2025 huggingface dataset:
Level dependence of distortion-product otoacoustic emissions measured at high frequencies in humans
Authors: Dreisbach Laura E. , Siegel Jonathan H.
Published: May 2005

Given that high-frequency hearing is most vulnerable to cochlear pathology, it is important to characterize distortion-product otoacoustic emissions (DPOAEs) measured with higher-frequency stimuli in order to utilize these measures in clinical applications. The purpose of this study was to explore the dependence of DPOAE amplitude on the levels of the evoking stimuli at frequencies greater than 8 kHz, and make comparisons with those data that have been extensively measured with lower-frequency stimuli. To accomplish this, DPOAE amplitudes were measured at six different f2 frequencies (2, 5, 10, 12, 14, and 16 kHz), with a frequency ratio (f2/f1) of 1.2, at five fixed levels (30 to 70 dB SPL) of one primary (either f1 or f2), while the other primary was varied in level (30 to 70 dB SPL). Generally, the level separation between the two primary tones (L1>L2) generating the largest DPOAE amplitude (referred to as the “optimal level separation”) decreased as the level of the fixed primary increased. Additionally, the optimal level separation was frequency dependent, especially at the lower fixed primary tone levels (⩽50 dB SPL). In agreement with previous studies, the DPOAE level exhibited greater dependence on L1 than on L2.
Two-tone distortion in intracochlear pressure
Authors: Dong Wei , Olson Elizabeth S.
Published: May 2005

Two-tone distortion was measured in the intracochlear pressure in the base of the gerbil cochlea, close to the sensory tissue, where the local motions and forces of the organ of Corti can be detected. The measurements probe both the underlying nonlinear process that generates two-tone distortion, and the filtering and spreading of the distortion products. Some of our findings are as follows: (1) The observations were consistent with previous observations of two-tone distortion in BM motion [J. Neurophysiol. 77, 2385–2399 (1997); J. Neurophysiol. 78, 261–270 (1997)]. (2) Frequency sweeps show distortion product tuning and phase-versus-frequency behavior that is similar, but not identical, to single tone tuning. (3) The decay of distortion products with distance from the basilar membrane confirms the feasibility that they could drive the stapes by a direct fluid route, as proposed by Ren [Nat. Neurosci. 7, 333–334 (2004)]. (4) The phases of the distortion products within a single family (the group of distortion products generated by a single primary pair) in some cases alternated between 0° and 180° when referenced to the phases of the primaries. This behavior is predicted by a simple compressive nonlinearity.
Auditory perception of sound source velocity
Authors: Kaczmarek Tomasz
Published: May 2005

In this study we investigate the perception of the velocity of linearly moving sound sources passing in front of a listener. The binaural simulation of motion used in two psychoacoustical experiments includes changes in the overall sound pressure level, the Doppler effect, and changes in interaural time differences. These changes are considered as cues for the perception of velocity. The present experiments are an extension of the experiments performed by Lutfi and Wang [J. Acoust. Soc. Am. 106, 919–928 (1999)]. The results of Experiment I show that the differential velocity threshold is independent of the reference velocity (10, 20, 30, and 40 m/s), varying across listeners from 1.5 to 4.6 m/s. In Experiment II, a method based on the successive elimination of cues in compared pairs of signals was employed to estimate the weights of potential cues for velocity discrimination. The magnitudes of all underlying cues at thresholds are reported. The experimental results show the subject’s preference for the Doppler cue and a weakest sensitivity to the cue related with interaural time differences. Finally, it was found that spatial differences in the source location at the endpoints of the motion trajectory are not a significant factor in the velocity discrimination task.
Optimal design of loudspeaker arrays for robust cross-talk cancellation using the Taguchi method and the genetic algorithm
Authors: Bai Mingsian R. , Tung Chih-Wei , Lee Chih-Chung
Published: May 2005

An optimal design technique of loudspeaker arrays for cross-talk cancellation with application in three-dimensional audio is presented. An array focusing scheme is presented on the basis of the inverse propagation that relates the transducers to a set of chosen control points. Tikhonov regularization is employed in designing the inverse cancellation filters. An extensive analysis is conducted to explore the cancellation performance and robustness issues. To best compromise the performance and robustness of the cross-talk cancellation system, optimal configurations are obtained with the aid of the Taguchi method and the genetic algorithm (GA). The proposed systems are further justified by physical as well as subjective experiments. The results reveal that large number of loudspeakers, closely spaced configuration, and optimal control point design all contribute to the robustness of cross-talk cancellation systems (CCS) against head misalignment.
Optimal nonlocal boundary control of the wide-angle parabolic equation for inversion of a waveguide acoustic field
Authors: Meyer Matthias , Hermand Jean-Pierre
Published: May 2005

This paper applies the concept of optimal boundary control for solving inverse problems in shallow water acoustics. To treat the controllability problem, a continuous analytic adjoint model is derived for the Claerbout wide-angle parabolic equation (PE) using a generalized nonlocal impedance boundary condition at the water-bottom interface. While the potential of adjoint methodology has been recently demonstrated for ocean acoustic tomography, this approach combines the advantages of exact transparent boundary conditions for the wide-angle PE with the concept of adjoint-based optimal control. In contrast to meta-heuristic approaches the inversion procedure itself is directly controlled by the waveguide physics and, in a numerical implementation based on conjugate gradient optimization, many fewer iterations are required for assessment of an environment that is supported by the underlying subbottom model. Furthermore, since regularization schemes are particularly important to enhance the performance of full-field acoustic inversion, special attention is devoted to the application of penalization methods to the adjoint optimization formalism. Regularization incorporates additional information about the desired solution in order to stabilize ill-posed inverse problems and identify useful solutions, a feature that is of particular importance for inversion of field data sampled on a vertical receiver array in the presence of measurement noise and modeling uncertainty. Results with test data show that the acoustic field and the bottom properties embedded in the control parameters can be efficiently retrieved.
Influence of viscosity on the diffraction of sound by a periodic array of screens
Authors: Homentcovschi Dorel , Miles Ronald N. , Tan Lin
Published: May 2005

The paper contains an analysis of the transmission of a pressure wave through a periodic grating including the influence of the air viscosity. The system of equations in this case consists of the compressible Navier–Stokes equations associated with no-slip boundary conditions on solid surfaces. The problem is reduced to two hypersingular integral equations for determining the velocity components along the slits. These equations are solved by using Galerkin’s method with some special trial functions. The results can be applied in designing protective screens for miniature microphones realized in the technology of micro-electro-mechanical systems (MEMS). In this case, the physical dimensions of the device are on the order of the viscous boundary layer so that the viscosity cannot be neglected. The microfluidic model of the screen consists of a periodic array of slits in a substrate. The analysis indicates that the openings in the screen should be on the order of 10 μm in order to avoid excessive attenuation of the signal.
Reduced order modeling of head related impulse responses for virtual acoustic displays
Authors: Grantham D. Wesley , Willhite Joel Andrew , Frampton Kenneth D. , Ashmead Daniel H.
Published: May 2005

This study investigated the use of reduced order head related impulse response (HRIR) models to improve the computational efficiency in acoustic virtual displays. State space models of varying order were generated from zero-elevation HRIRs using a singular value decomposition technique. A source identification experiment was conducted under anechoic conditions in which three subjects were required to localize sounds in the front horizontal plane. The sounds were either (1) real sources (emitted by individual loudspeakers in a semi-circular array), (2) virtual sources generated from the original HRIRs, or (3) virtual sources generated using reduced order state space models. All virtual sources were created by simultaneous activation of two loudspeakers at ±30° using a virtual source imaging technique based on either the measured or modeled HRIRs. The errors in the perceived direction of the virtual sources generated from the reduced order models were compared to errors in localization using the original HRIRs. The results demonstrate that a very significant reduction in model size can be achieved without significantly affecting the fidelity of the virtual display of horizontally placed sources.
Echolocation signals of the free-ranging Yangtze finless porpoise (Neophocaena phocaenoides asiaeorientialis)
Authors: Li Songhai , Wang Kexiong , Wang Ding , Akamatsu Tomonari
Published: May 2005

This paper describes the high-frequency echolocation signals from free-ranging Yangtze finless porpoise in the Tian-e-zhou Baiji National Natural Reserve in Hubei Province, China. Signal analysis showed that the Yangtze finless porpoise clicks are typical high-frequency narrow-band (relative width of the frequency spectrum Q=6.6±1.56, N=548) ultrasonic pulses. The peak frequencies of the typical clicks range from 87 to 145 kHz with an average of 125±6.92 kHz. The durations range from 30 to 122 μs with an average of 68±14.12 μs. The characteristics of the signals are similar to those of other members of the Phocoenidae as well as the distantly related delphinids, Cephalorhynchus spp. Comparison of these signals to those of the baiji (Lipotes vexillifer), who occupies habitat similar to that of the Yangtze finless porpoise, showed that the peak frequencies of clicks produced by the Yangtze finless porpoise are remarkably higher than those produced by the baiji. Difference in peak frequency between the two species is probably linked to the different size of preferred prey fish. Clear double-pulse and multi-pulse reverberation structures of clicks are noticed, and there is no indication of any low-frequency (<70 kHz) components during the recording period.
Sound production by North Atlantic right whales (Eubalaena glacialis) in surface active groups
Authors: Parks Susan E. , Tyack Peter L.
Published: May 2005

The surface active group (SAG) is the most commonly observed surface social behavior of North Atlantic right whales. Recordings were made from 52 SAGs in the Bay of Fundy, Canada between July and September, from 1999 to 2002. The call types recorded from these groups were similar to those described previously for Southern right whales (Eubalaena australis), with six major call types being termed scream, gunshot, blow, upcall, warble, and downcall. The percentage of total calls of each call type depended on the group size and composition. The most common call type recorded was the scream call. The scream calls were produced by the focal female in a SAG. Production of other sound types can be attributed to whales other than the focal female, with gunshot and upcalls produced by males, and warble calls produced by female calves. The source levels for these sounds range from 137 to 162 dB rms re 1 μPa-m for tonal calls and 174 to 192 dB rms for broadband gunshot sounds.
Comparing different estimates of cochlear compression in listeners with normal and impaired hearing
Authors: Rosengard Peninah S. , Oxenham Andrew J. , Braida Louis D.
Published: May 2005

A loss of cochlear compression may underlie many of the difficulties experienced by hearing-impaired listeners. Two behavioral forward-masking paradigms that have been used to estimate the magnitude of cochlear compression are growth of masking (GOM) and temporal masking (TM). The aim of this study was to determine whether these two measures produce within-subjects results that are consistent across a range of signal frequencies and, if so, to compare them in terms of reliability or efficiency. GOM and TM functions were measured in a group of five normal-hearing and five hearing-impaired listeners at signal frequencies of 1000, 2000, and 4000 Hz. Compression values were derived from the masking data and confidence intervals were constructed around these estimates. Both measures produced comparable estimates of compression, but both measures have distinct advantages and disadvantages, so that the more appropriate measure depends on factors such as the frequency region of interest and the degree of hearing loss. Because of the long testing times needed, neither measure is suitable for clinical use in its current form.
Transmission loss measurement of consolidated granular media (L)
Authors: Pispola Giulio , Horoshenkov Kirill V. , Asdrubali Francesco
Published: May 2005

The normal incidence transmission loss of a new class of sustainable acoustic materials, i.e. consolidated granular media, has been measured to determine their sound insulating performance. Tests performed on different samples in a standing wave tube suggest that the traditional method employing an anechoic termination assumption can yield serious errors because its accuracy depends significantly on the properties of both the termination and the tested sample. Since it is not possible to implement a perfect anechoic termination over a wide frequency range, a well-developed alternative approach has been adopted. A simple theoretical analysis has been carried out to compare these two methods. It has been shown that the two-load method, based on two sets of measurements with different boundary conditions at the tube termination, can give more reliable and predictable results. Greater discrepancies have been observed in the case of the anechoic termination method applied to samples with higher values of flow resistivity. Results of the two-load method match well with predictions based on a simple model for acoustic transmission through a porous plate.
Time reversal of noise sources in a reverberation room
Authors: Ribay Guillemette , de Rosny Julien , Fink Mathias
Published: May 2005

Usually, time reversal is studied with pulsed emissions. Here, the properties of time reversal of the acoustic field emitted by noise sources in a reverberation room are studied numerically, theoretically, and experimentally. A time domain numerical simulation of a two-dimensional enclosure shows that the intensity of a time-reversed noise is strongly enhanced right on the initial source position. A theory based on the link that exists between time reversal of noise and the “well-known” time reversal of short pulse is developed. One infers that the focal spot size equals half a wavelength and the signal to noise ratio only depends on the number of transceivers in the time reversal mirror. This last property is characteristic of the time reversal of noise. Experimental results are obtained in a 5×3×3 m3 reverberation room. The working frequency range varies from 300 Hz to 2 kHz. The ability of the time reversal process to physically reconstruct the image of two noise sources is studied. To this end, care is given to the technique to separate two close random sources, and also to the influence of temperature fluctuations on the focusing quality.
Comparison of measurements of phase velocity in human calcaneus to Biot theory
Authors: Wear Keith A. , Laib Andres , Stuber Angela P. , Reynolds James C.
Published: May 2005

Biot’s theory for elastic propagation in porous media has previously been shown to be useful for modeling the dependence of phase velocity on porosity in bovine cancellous bone in vitro. In the present study, Biot’s theory is applied to measurements of porosity-dependent phase velocity in 53 human calcanea in vitro. Porosity was measured using microcomputed tomography for some samples (n=23) and estimated based on bone mineral densitometry for the remaining samples (n=30). The phase velocity at 500 kHz was measured in a water tank using a through-transmission technique. Biot’s theory performed well for the prediction of the dependence of sound speed on porosity. The trend was quasilinear, but both the theory and experiment show similar slight curvature. The root mean square error (RMSE) of predicted versus measured sound speed was 15.8 m/s.
Energy transmission in a mechanically-linked double-wall structure coupled to an acoustic enclosure
Authors: Cheng L. , Li Y. Y. , Gao J. X.
Published: May 2005

The energy transmission in a mechanically linked double-wall structure into an acoustic enclosure is studied in this paper. Based on a fully coupled vibro-acoustic formulation, focus is put on investigating the effect of the air gap and mechanical links between the two panels on the energy transmission and noise insulation properties of such structures. An approximate formula reflecting the gap effect on the lower-order coupled frequencies of the system is proposed. A criterion, based on the ratio between the aerostatic stiffness of the gap cavity and the stiffness of the link, is proposed to predict the dominant transmitting path, with a view to provide guidelines for the design of appropriate control strategies. Numerical results reveal the existence of three distinct zones, within which energy transmission takes place following different mechanisms and transmitting paths. Corresponding effects on noise insulation properties of the double-wall structure are also investigated.
Finite element prediction of wave motion in structural waveguides
Authors: Mace Brian R. , Duhamel Denis , Brennan Michael J. , Hinke Lars
Published: May 2005

A method is presented by which the wavenumbers for a one-dimensional waveguide can be predicted from a finite element (FE) model. The method involves postprocessing a conventional, but low order, FE model, the mass and stiffness matrices of which are typically found using a conventional FE package. This is in contrast to the most popular previous waveguide/FE approach, sometimes termed the spectral finite element approach, which requires new spectral element matrices to be developed. In the approach described here, a section of the waveguide is modeled using conventional FE software and the dynamic stiffness matrix formed. A periodicity condition is applied, the wavenumbers following from the eigensolution of the resulting transfer matrix. The method is described, estimation of wavenumbers, energy, and group velocity discussed, and numerical examples presented. These concern wave propagation in a beam and a simply supported plate strip, for which analytical solutions exist, and the more complex case of a viscoelastic laminate, which involves postprocessing an ANSYS FE model. The method is seen to yield accurate results for the wavenumbers and group velocities of both propagating and evanescent waves.
A categorization method applied to the study of urban road traffic noise
Authors: Barrigón Morillas Juan Miguel , Gómez Escobar Valentı́n , Méndez Sierra Juan Antonio , Vı́lchez-Gómez Rosendo , Vaquero José M. , Trujillo Carmona José
Published: May 2005

The present work summarizes a study of the hypothesis that urban noise can be stratified by measuring street noise according to a prior classification of a town’s streets according to their use in communicating the different zones of the town. The method was applied to five medium-sized Spanish towns (Vitoria-Gasteiz, Salamanca, Badajoz, Cáceres, and Mérida) with populations ranging from 218 000 down to 50 000 and with different socio-economic characteristics, climate, etc. As the initial hypothesis of the work was that traffic is the main source of urban noise and is also the principal cause of the variability of the sound levels measured in urban settings, the study focused only on the five nonpedestrian categories of streets. The continuous equivalent sound level (Leq) was employed in the statistical analysis as it is commonly used as a general noise index, and other noise indicators such as LDN or LDEN are calculated from it. It was found that, although differences between the medians were not statistically significant in some of the towns for certain pairs of adjacent categories, the differences between pairs of nonadjacent categories were always significant, indicative of the stratification of noise in these five towns. Further studies on other medium-sized towns and on large towns and small villages would be needed to test whether the present definition of street categories is extensible elsewhere without modification.
Dispersion-based short-time Fourier transform applied to dispersive wave analysis
Authors: Hong Jin-Chul , Sun Kyung Ho , Kim Yoon Young
Published: May 2005

Although time-frequency analysis is effective for characterizing dispersive wave signals, the time-frequency tilings of most conventional analysis methods do not take into account dispersion phenomena. An adaptive time-frequency analysis method is introduced whose time-frequency tiling is determined with respect to the wave dispersion characteristics. In the dispersion-based time-frequency tiling, each time-frequency atom is adaptively rotated in the time-frequency plane, depending on the local wave dispersion. Although this idea can be useful in various problems, its application to the analysis of dispersive wave signals has not been made. In this work, the adaptive time-frequency method was applied to the analysis of dispersive elastic waves measured in waveguide experiments and a theoretical investigation on its time-frequency resolution was presented. The time-frequency resolution of the proposed transform was then compared with that of the standard short-time Fourier transform to show its effectiveness in dealing with dispersive wave signals. In addition, to facilitate the adaptive time-frequency analysis of experimentally measured signals whose dispersion relations are not known, an iterative scheme for determining the relationships was developed. The validity of the present approach in dealing with dispersive waves was verified experimentally.
Adaptive window-length detection of underwater transients using wavelets
Authors: Carevic Dragana
Published: May 2005

This paper describes a detection method that adapts to unknown characteristics of the underlying transient signal, such as location, length, and time-frequency content. It applies a set of embedded detectors tuned to a number of signal partitions. The detectors are based on the wavelet theory, whereby two different techniques are examined, one using local Fourier transform and the other using discrete wavelet transform. The detection statistics are computed so as to enable prewhitening of unknown colored noise and to allow for a constant false-alarm rate detection. An adapted segmentation of the signal is next obtained with a goal of finding the largest detection statistics within each segment of the partition. The detectors are tested using several underwater acoustic transient signals buried in ambient sea noise.
Using the short-time correlation coefficient to compare transient- and derived, noise-evoked otoacoustic emission temporal waveforms
Authors: Harte James M. , Elliott Stephen J.
Published: May 2005

Transient-evoked otoacoustic emissions (TEOAEs) and derived, noise-evoked otoacoustic emissions (derived-NEOAEs) were measured in seven normally hearing subjects. The evoked OAEs were all recorded at three excitation levels chosen to ensure that the OAE level curve compressive region was reached. The short-time correlation coefficient (STCC) was used to compare the OAE waveforms at different excitation levels, and thus estimate the time over which the response exceeds the noise level. The short-time correlation for TEOAEs is significant for longer than it is for NEOAEs, particularly in some individuals, and the STCC allows this to be quantified. This suggests that derived NEOAEs do not display the highly synchronized dominant frequencies often seen in TEOAEs. This has been confirmed by examining the derived frequency responses for the two types of excitation. Conventional TEOAEs thus appear to measure a combination of two conceptually different processes, while NEOAEs measure just one.
Ultrasonic relaxation and internal rotation in butyl formate (L)
Authors: Mirzaev S. Z. , Bakaeva Z. S. , Khabibullaev P. K. , Kononenko V. S.
Published: May 2005

The acoustic spectra of liquid butyl formate have been investigated in the frequency range from 0.1 to 150 MHz and at the temperatures 20 °C, 50 °C, and 80 °C. The ultrasonic spectra of pure butyl formate show a single relaxation term in the frequency range between 200 kHz and 2 MHz. The relaxation process has been assigned to the cis and trans molecular conformations.
Sound of shallow and deep water lobsters: Measurements, analysis, and characterization (L)
Authors: Latha G. , Senthilvadivu S. , Venkatesan R. , Rajendran V.
Published: May 2005

Study of sound made by marine species aid in ambient noise studies and characterization. This letter presents the work carried out on measurement of sound made by lobsters in a controlled environment and the data processing and the spectral analysis to identify the frequency contents. Lobsters collected in the shallow waters as well as deep waters in the ocean have been used for the sound measurement. The Panulirus Homarus and Palinustur Waguersis species were kept in a tank in a laboratory and measurements were made. Their fundamental frequencies, harmonics, and peaks are analyzed in the band 3 to 100 kHz under different conditions such as molting and nonmolting states. Analysis with respect to diurnal variations is also carried out. The results show that lobsters produce sound like musical instruments, which agree with the observations of Patek [Nature (London) 411, 153–154 (2001)].
Wave-induced fluid flow in random porous media: Attenuation and dispersion of elastic waves
Authors: Müller Tobias M. , Gurevich Boris
Published: May 2005

A detailed analysis of the relationship between elastic waves in inhomogeneous, porous media and the effect of wave-induced fluid flow is presented. Based on the results of the poroelastic first-order statistical smoothing approximation applied to Biot’s equations of poroelasticity, a model for elastic wave attenuation and dispersion due to wave-induced fluid flow in 3-D randomly inhomogeneous poroelastic media is developed. Attenuation and dispersion depend on linear combinations of the spatial correlations of the fluctuating poroelastic parameters. The observed frequency dependence is typical for a relaxation phenomenon. Further, the analytic properties of attenuation and dispersion are analyzed. It is shown that the low-frequency asymptote of the attenuation coefficient of a plane compressional wave is proportional to the square of frequency. At high frequencies the attenuation coefficient becomes proportional to the square root of frequency. A comparison with the 1-D theory shows that attenuation is of the same order but slightly larger in 3-D random media. Several modeling choices of the approach including the effect of cross correlations between fluid and solid phase properties are demonstrated. The potential application of the results to real porous materials is discussed.
Acoustic positioning using multiple microphone arrays
Authors: Liu Hui , Milios Evangelos
Published: May 2005

Passive acoustic techniques are presented to solve the localization problem of a sound source in three-dimensional space using off-the-shelf hardware. Multiple microphone arrays are employed, which operate independently, in estimating the direction of arrival of sound, or, equivalently, a direction vector from the array’s geometric center towards the source. Direction vectors and array centers are communicated to a central processor, where the source is localized by finding the intersection of the direction lines defined by the direction vectors and the associated array centers. The performance of the method in the air is demonstrated experimentally and compared with a state-of-the-art method that requires centralized digitization of the signals from the microphones of all the arrays.
Effect of season and meteorological conditions on community noise annoyance
Authors: Miedema Henk M. E. , Fields James M. , Vos Henk
Published: May 2005

More than 80 000 residents’ responses to transportation noise from 42 studies conducted at different times of year provide statistical estimates of the effects of season and meteorological conditions on community response to noise. The strongest evidence for a seasonal effect comes from 7 years of continuous daily interviewing of nationally representative probability samples in the Netherlands. Long-term annoyance with noise is slightly, but statistically significantly, higher in the summer than in the winter. Analyses of 41 other surveys drawn from diverse countries, climates, and times of year also provide evidence that noise annoyance varies over the year, is increased by temperature, and may be increased by more sunshine, less precipitation, and reduced wind speeds. These findings are not sufficiently precise to determine whether the apparent relationships with meteorological conditions are only the result of seasonal variations or are also the result of differences in the climate at different locations. There is not consistent evidence that the meteorological conditions on the day of the interview or the immediately preceding days have any more effect on long-term noise annoyance measures than do the conditions over the immediately preceding weeks or months.
Do Satellites Detect Trends in Surface Solar Radiation?
Authors: Pinker R. T. , Zhang B. , Dutton E. G.
Published: May 2005

Long-term variations in solar radiation at Earth's surface (
S
) can affect our climate, the hydrological cycle, plant photosynthesis, and solar power. Sustained decreases in
S
have been widely reported from about the year 1960 to 1990. Here we present an estimate of global temporal variations in
S
by using the longest available satellite record. We observed an overall increase in
S
from 1983 to 2001 at a rate of 0.16 watts per square meter (0.10%) per year; this change is a combination of a decrease until about 1990, followed by a sustained increase. The global-scale findings are consistent with recent independent satellite observations but differ in sign and magnitude from previously reported ground observations. Unlike ground stations, satellites can uniformly sample the entire globe.
The Holocene Asian Monsoon: Links to Solar Changes and North Atlantic Climate
Authors: Wang Yongjin , Cheng Hai , Edwards R. Lawrence , He Yaoqi , Kong Xinggong , An Zhisheng , Wu Jiangying , Kelly Megan J. , Dykoski Carolyn A. , Li Xiangdong
Published: May 2005

A 5-year-resolution absolute-dated oxygen isotope record from Dongge Cave, southern China, provides a continuous history of the Asian monsoon over the past 9000 years. Although the record broadly follows summer insolation, it is punctuated by eight weak monsoon events lasting ∼1 to 5 centuries. One correlates with the “8200-year” event, another with the collapse of the Chinese Neolithic culture, and most with North Atlantic ice-rafting events. Cross-correlation of the decadal- to centennial-scale monsoon record with the atmospheric carbon-14 record shows that some, but not all, of the monsoon variability at these frequencies results from changes in solar output.
Swimming Against the Flow: A Mechanism of Zooplankton Aggregation
Authors: Genin Amatzia , Jaffe Jules S. , Reef Ruth , Richter Claudio , Franks Peter J. S.
Published: May 2005

Zooplankton reside in a constantly flowing environment. However, information about their response to ambient flow has remained elusive, because of the difficulties of following the individual motions of these minute, nearly transparent animals in the ocean. Using a three-dimensional acoustic imaging system, we tracked >375,000 zooplankters at two coastal sites in the Red Sea. Resolution of their motion from that of the water showed that the animals effectively maintained their depth by swimming against upwelling and downwelling currents moving at rates of up to tens of body lengths per second, causing their accumulation at frontal zones. This mechanism explains how oceanic fronts become major feeding grounds for predators and targets for fishermen.
A Synaptonemal Complex Protein Promotes Homology-Independent Centromere Coupling
Authors: Tsubouchi Tomomi , Roeder G. Shirleen
Published: May 2005

We describe a process in meiotic cells of budding yeast in which chromosomes become joined together in pairs at their centromeres independent of chromosomal homology. These centromeric interactions depend on the synaptonemal complex component Zip1. During meiosis in wild-type diploids, centromere couples are initially nonhomologous and then undergo switching until all couples involve homologs. This transition to homologous coupling depends on Spo11, a protein required for the initiation of meiotic recombination. Regions of synaptonemal complex assembled early in meiosis are often centromere-associated. We propose that centromere coupling facilitates homolog pairing and promotes synapsis initiation.
Attractor Dynamics in the Hippocampal Representation of the Local Environment
Authors: Wills Tom J. , Lever Colin , Cacucci Francesca , Burgess Neil , O'Keefe John
Published: May 2005

Memories are thought to be attractor states of neuronal representations, with the hippocampus a likely substrate for context-dependent episodic memories. However, such states have not been directly observed. For example, the hippocampal place cell representation of location was previously found to respond continuously to changes in environmental shape alone. We report that exposure to novel square and circular environments made of different materials creates attractor representations for both shapes: Place cells abruptly and simultaneously switch between representations as environmental shape changes incrementally. This enables study of attractor dynamics in a cognitive representation and may correspond to the formation of distinct contexts in context-dependent memory.
Zircon Thermometer Reveals Minimum Melting Conditions on Earliest Earth
Authors: Watson E. B. , Harrison T. M.
Published: May 2005

Ancient zircons from Western Australia's Jack Hills preserve a record of conditions that prevailed on Earth not long after its formation. Widely considered to have been a uniquely violent period geodynamically, the Hadean Eon [4.5 to 4.0 billion years ago (Ga)] has recently been interpreted by some as far more benign—possibly even characterized by oceans like those of the present day. Knowledge of the crystallization temperatures of the Hadean zircons is key to this debate. A thermometer based on titanium content revealed that these zircons cluster strongly at ∼700°C, which is indistinguishable from temperatures of granitoid zircon growth today and strongly suggests a regulated mechanism producing zircon-bearing rocks during the Hadean. The temperatures substantiate the existence of wet, minimum-melting conditions within 200 million years of solar system formation. They further suggest that Earth had settled into a pattern of crust formation, erosion, and sediment recycling as early as 4.35 Ga.
Levels of Recent Thymic Emigrant Cells Decrease in Children Undergoing Partial Thymectomy during Cardiac Surgery
Authors: Madhok Ashish B. , Chandrasekran A. , Parnell Vincent , Gandhi Mysore , Chowdhury Devyani , Pahwa Savita
Published: May 2005

The human thymus is required for establishment of a T-cell pool in fetal life, but postnatal thymectomy is not known to cause immunodeficiency. T-cell emigration from thymus (thymic recent emigrants [TRECs]) is a continuous thymic-dependent process. We studied TREC levels pre- and post-partial thymectomy in children undergoing cardiac surgery. TRECs were quantitated by real-time PCR in peripheral blood lymphocytes of 24 children (0 to 12 years). TREC values were 47916 ± 9271 pre-partial thymectomy and 33157 ± 8479 post-partial thymectomy in 11 paired patients (
P
= 0.014). Interval between pre- and post-partial thymectomy was 8.8 days ± 5.8 days. Another group of 8 children had 30384 ± 9748 TRECs 16 days to 6 years post-partial thymectomy. There was a significant drop in TREC values post-partial thymectomy in the immediate postoperative period compared to prethymectomy TREC levels. While decreased thymic output may persist, the long-term implications were not evaluated in this patient population.
Duplex Microsphere-Based Immunoassay for Detection of Anti-West Nile Virus and Anti-St. Louis Encephalitis Virus Immunoglobulin M Antibodies
Authors: Johnson Alison J. , Noga Amanda J. , Kosoy Olga , Lanciotti Robert S. , Johnson Alicia A. , Biggerstaff Brad J.
Published: May 2005

West Nile (WN) virus was introduced into the United States in 1999, when the first human cases of WN fever and encephalitis appeared in New York City. From there, the virus has spread throughout North America, in some areas cocirculating with the related flavivirus St. Louis encephalitis (SLE) virus. Public health laboratories currently use an immunoglobulin M (IgM) antibody capture enzyme-linked immunosorbent assay (MAC-ELISA) as a primary test for human serodiagnosis, followed by a confirmatory plaque-reduction neutralization test (PRNT). The MAC-ELISAs take 2 days to perform; therefore there is a need for a more rapid test. This report describes a duplex microsphere-based immunoassay (MIA) that shortens the test processing time to about 4.5 h. The assay employs two sets of microspheres coupled to a single flavivirus group-reactive antibody, which are used to capture the WN and SLE viral antigens independently. Immunoglobulin G-depleted serum is concurrently assayed for IgM antibodies to each of the viral antigens. The results are standardized and classified by using quadratic discriminant analysis so that a single result, anti-WN IgM-positive, anti-SLE IgM-positive, negative, or nonspecific, can be determined. The duplex MIA results compared favorably to those of the plaque-reduction neutralization test and MAC-ELISA. The assay proved to be reproducible, produced accurate classifications as to the infecting virus, and was specific.
Immunoglobulin E Reactivity of Recombinant Allergen Tyr p 13 from
Tyrophagus putrescentiae
Homologous to Fatty Acid Binding Protein
Authors: Jeong Kyoung Yong , Kim Woo Kyung , Lee Jae Sik , Lee Jongweon , Lee In-Yong , Kim Kyu-Earn , Park Jung Won , Hong Chein-Soo , Ree Han-Il , Yong Tai-Soon
Published: May 2005

The storage mite,
Tyrophagus putrescentiae
, is one of the important causes of allergic disorders. Fifteen allergenic components were demonstrated in storage mite by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblotting, but only the group 2 allergen Tyr p 2 has been cloned and characterized. In this study, we attempted to identify and characterize new allergens from
T. putrescentiae
, which is a dominant species of storage mite in Korea. Expressed sequence tags were analyzed to identify possible storage mite allergens, and the cDNA sequence encoding a protein homologous to fatty acid binding protein, a mite group 13 allergen, was identified and named Tyr p 13. Its deduced amino acid sequence showed 61.1 to 85.3% identity with other mite group 13 allergens. The recombinant protein was expressed in
Escherichia coli
using a pET 28b vector system, and its allergenicity was investigated by enzyme-linked immunosorbent assay (ELISA). The recombinant allergen was detected in 5 of 78 (6.4%)
T. putrescentiae
-positive sera tested, and it inhibited 61.9% of immunoglobulin E binding to crude extract at an inhibitor concentration of 10 μg/ml by inhibition ELISA using serum from the patient who showed the strongest reaction by ELISA. In this study, a novel allergen was identified in
T. putrescentiae
. This allergen could be helpful for more-detailed characterizations of storage mite allergy.
Development of Recombinant Chimeric Antigen Expressing Immunodominant B Epitopes ofLeishmania infantumfor Serodiagnosis of Visceral Leishmaniasis
Authors: Boarino A. , Scalone A. , Gradoni L. , Ferroglio E. , Vitale F. , Zanatta R. , Giuffrida M. G. , Rosati S.
Published: May 2005

Wild canids and domestic dogs are the main reservoir of zoonotic visceral leishmaniasis (VL) caused byLeishmania infantum(syn.:Leishmania chagasi). Serological diagnosis of VL is therefore important in both human and dog leishmaniasis from a clinical and epidemiological point of view. Routine diagnosis of VL is traditionally carried out by immunofluorescent antibody test (IFAT), which is laborious and difficult to standardize and to interpret. In the last decade, however, several specific antigens ofLeishmania infantumhave been characterized, allowing the development of a recombinant-based immunoassay. Among them, the whole open reading frame encoding K9 antigen, the gene fragment encoding the repetitive sequence of K26, and the 3′-terminal gene fragment of the kinesin-related protein (K39sub) were previously evaluated as diagnostic markers for canine leishmaniasis and proved to be independent in their antibody reactivity. Since sensitivity of serological test is usually higher in multiple-epitope format, in this study the relevant epitopes of K9, K26, and K39 antigens were joined by PCR strategy to produce the chimeric recombinant protein. The resulting mosaic antigen was found highly expressed inEscherichia coliand efficiently purified by affinity chromatography. Antigenic properties of this recombinant antigen were evaluated by indirect enzyme-linked immunosorbent assay (ELISA) using a panel of human and dog sera previously characterized by parasitological and/or serological techniques. Chimeric ELISA showed 99% specificity in both human (n= 180) and canine (n= 343) control groups, while sensitivity was higher in canine VL (96%,n= 213) than in human VL (82%,n= 185). Accordingly, concordance between IFAT and canine chimeric ELISA (k= 0.95, 95% confidence interval = 0.93 to 0.98) was higher than between IFAT and human chimeric ELISA (k= 0.81, 95% confidence interval = 0.76 to 0.87). Results suggest the potential use of this new antigen for routine serodiagnosis of VL in both human and canine hosts.
Detection by Radioligand Assay of Antibodies against Borna Disease Virus in Patients with Various Psychiatric Disorders
Authors: Matsunaga Hidenori , Tanaka Susumu , Sasao Fuyoko , Nishino Yoshii , Takeda Masatoshi , Tomonaga Keizo , Ikuta Kazuyoshi , Amino Nobuyuki
Published: May 2005

Using a radioligand assay, which preserves the natural form of the antigen, antibodies against Borna disease virus nucleoprotein and phosphoprotein were detected in 11 and 19 sera of 171 psychiatric patients, respectively. Compared with results by Western blotting, three and nine sera were concordantly positive, respectively. The four sera showing the highest levels of antibodies by radioligand assay were all negative by Western blotting; however, dilution and inhibition tests supported the positive results. Our results suggest the importance of conformational structure to detect human anti-Borna disease virus antibodies.
Strongyloides Hyperinfection and Hypogammaglobulinemia
Authors: Seet Raymond C. S. , Lau Lee Gong , Tambyah Paul Ananth
Published: May 2005

We report strongyloides hyperinfection in two patients with generalized hypogammaglobulinemia from multiple myeloma and nephrotic syndrome, despite a significant strongyloides-specific immunoglobulin G (IgG) response. In contrast to reports on animals, where human IgG was shown to be a protective antibody, our observation suggests that in humans, immunity to the infective-stage larvae is not protective against the autoinfective larvae, which are the causative agents of strongyloides hyperinfection.
Respiration and Growth of
Shewanella oneidensis
MR-1 Using Vanadate as the Sole Electron Acceptor
Authors: Carpentier Wesley , De Smet Lina , Van Beeumen Jozef , Brigé Ann
Published: May 2005

Shewanella oneidensis
MR-1 is a free-living gram-negative γ-proteobacterium that is able to use a large number of oxidizing molecules, including fumarate, nitrate, dimethyl sulfoxide, trimethylamine
N
-oxide, nitrite, and insoluble iron and manganese oxides, to drive anaerobic respiration. Here we show that
S. oneidensis
MR-1 is able to grow on vanadate as the sole electron acceptor. Oxidant pulse experiments demonstrated that proton translocation across the cytoplasmic membrane occurs during vanadate reduction. Proton translocation is abolished in the presence of protonophores and the inhibitors 2-heptyl-4-hydroxyquinoline
N
-oxide and antimycin A. Redox difference spectra indicated the involvement of membrane-bound menaquinone and cytochromes
c
, which was confirmed by transposon mutagenesis and screening for a vanadate reduction-deficient phenotype. Two mutants which are deficient in menaquinone synthesis were isolated. Another mutant with disruption in the cytochrome
c
maturation gene
ccmA
was unable to produce any cytochrome
c
and to grow on vanadate. This phenotype could be restored by complementation with the pEC86 plasmid expressing
ccm
genes from
Escherichia coli
. To our knowledge, this is the first report of
E. coli ccm
genes being functional in another organism. Analysis of an
mtrB
-deficient mutant confirmed the results of a previous paper indicating that OmcB may function as a vanadate reductase or may be part of a vanadate reductase complex.
Global Transcriptional and Proteomic Analysis of the Sig1 Heat Shock Regulon ofDeinococcus radiodurans
Authors: Schmid Amy K. , Howell Heather A. , Battista John R. , Peterson Scott N. , Lidstrom Mary E.
Published: May 2005

Thesig1gene, predicted to encode an extracytoplasmic function-type heat shock sigma factor ofDeinococcus radiodurans, has been shown to play a central role in the positive regulation of the heat shock operonsgroESLanddnaKJ.To determine if Sig1 is required for the regulation of additional heat shock genes, we monitored the global transcriptional and proteomic profiles of aD. radioduransR1sig1mutant and wild-type cells in response to elevated temperature stress. Thirty-one gene products were identified that showed heat shock induction in the wild type but not in thesig1mutant. Quantitative real-time PCR experiments verified the transcriptional requirement of Sig1 for the heat shock induction of the mRNA of five of these genes—dnaK,groES, DR1314,pspA, andhsp20. hsp20appears to encode a new member of the small heat shock protein superfamily, DR1314 is predicted to encode a hypothetical protein with no recognizable orthologs, andpspAis predicted to encode a protein involved in maintenance of membrane integrity. Deletion mutation analysis demonstrated the importance in heat shock protection ofhsp20and DR1314. The promoters ofdnaKJE,groESL, DR1314,pspA, andhsp20were mapped and, combined with computer-based pattern searches of the upstream regions of the 26 other Sig1 regulon members, these results suggested that Sig1 might recognize both σ70-type and σW-type promoter consensus sequences. These results expand theD. radioduransSig1 heat shock regulon to include 31 potential new members, including not only factors with cytoplasmic functions, such asgroESanddnaK, but also those with extracytoplasmic functions, likepspA.