bluuebunny/crossref_metadata_2025 huggingface dataset:
An iterative method to solve acoustic scattering problems using a boundary integral equation
Authors: Rao Sadasiva M.
Published: October 2011

In this work, a simple iterative method to solve the acoustic scattering/radiation problems using the boundary integral equation (BIE) formulation is presented. The operator equation obtained in the BIE formulation is converted into a matrix equation using the well-known method of moments solution procedure. The present method requires much fewer mathematical operations per iteration when compared to other available iterative methods. Further, the present iterative method can easily handle multiple incident fields, a highly desirable feature not available in any other iterative method, much the same way as direct solution techniques. Several numerical examples are presented to illustrate the efficiency and accuracy of the method.
Effect of randomly varying impedance on the interference of the direct and ground-reflected waves
Authors: Ostashev Vladimir E. , Wilson D. Keith , Vecherin Sergey N.
Published: October 2011

A randomly varying ground impedance is introduced into the solution for the sound field produced by a point source in a homogeneous atmosphere above a flat ground. The results show that in general the ground with a random impedance cannot be represented by an effective, non-random impedance. The behavior of the solution is studied with a relaxation model for the impedance in which porosity and the static flow resistivity are random variables. Mean values and standard deviations are adopted from measurements of two types of ground surfaces. For both surfaces, the mean intensity of the sound field above a random-impedance ground deviates only slightly from the intensity above a non-random impedance. The normalized standard deviation of intensity fluctuations can, however, be greater than one, thus indicating that for a particular realization of the random impedance, the sound intensity might significantly deviate from the intensity for a non-random impedance.
A comparison of methods to compute the “effective duration” of the autocorrelation function and an alternative proposal
Authors: D’Orazio Dario , De Cesaris Simona , Garai Massimo
Published: October 2011

The “effective duration” of the autocorrelation function (ACF), τe, is an important factor in architectural and musical acoustics. For a general application, an accurate evaluation of τe is relevant. This paper is focused to the methods for the extraction of τe values from the ACF. Various methods have been proposed in literature for the extraction of the τe from a given signal, but these methods are not unambiguously defined or may not work properly in case of particular signals. Therefore, the general use of these methods may sometimes give rise to questionable results. In the present work, the methods existing in literature for extracting τe are analyzed, their advantages and drawbacks are summarized, and finally an alternative method is proposed. The proposed algorithm is compared to those found in previous literature, applying them on the same sound signals (classic literature references and other ones publicly available on the Internet). It is shown that the results obtained with the proposed method are consistent with the results of the previous literature; moreover the proposed method may overcome some of the limitations of the existing methods.
Automated extraction of odontocete whistle contours
Authors: Roch Marie A. , Scott Brandes T. , Patel Bhavesh , Barkley Yvonne , Baumann-Pickering Simone , Soldevilla Melissa S.
Published: October 2011

Many odontocetes produce frequency modulated tonal calls known as whistles. The ability to automatically determine time × frequency tracks corresponding to these vocalizations has numerous applications including species description, identification, and density estimation. This work develops and compares two algorithms on a common corpus of nearly one hour of data collected in the Southern California Bight and at Palmyra Atoll. The corpus contains over 3000 whistles from bottlenose dolphins, long- and short-beaked common dolphins, spinner dolphins, and melon-headed whales that have been annotated by a human, and released to the Moby Sound archive. Both algorithms use a common signal processing front end to determine time × frequency peaks from a spectrogram. In the first method, a particle filter performs Bayesian filtering, estimating the contour from the noisy spectral peaks. The second method uses an adaptive polynomial prediction to connect peaks into a graph, merging graphs when they cross. Whistle contours are extracted from graphs using information from both sides of crossings. The particle filter was able to retrieve 71.5% (recall) of the human annotated tonals with 60.8% of the detections being valid (precision). The graph algorithm’s recall rate was 80.0% with a precision of 76.9%.
Investigation of spherical loudspeaker arrays for local active control of sound
Authors: Peleg Tomer , Rafaely Boaz
Published: October 2011

Active control of sound can be employed globally to reduce noise levels in an entire enclosure, or locally around a listener’s head. Recently, spherical loudspeaker arrays have been studied as multiple-channel sources for local active control of sound, presenting the fundamental theory and several active control configurations. In this paper, important aspects of using a spherical loudspeaker array for local active control of sound are further investigated. First, the feasibility of creating sphere-shaped quiet zones away from the source is studied both theoretically and numerically, showing that these quiet zones are associated with sound amplification and poor system robustness. To mitigate the latter, the design of shell-shaped quiet zones around the source is investigated. A combination of two spherical sources is then studied with the aim of enlarging the quiet zone. The two sources are employed to generate quiet zones that surround a rigid sphere, investigating the application of active control around a listener’s head. A significant improvement in performance is demonstrated in this case over a conventional headrest-type system that uses two monopole secondary sources. Finally, several simulations are presented to support the theoretical work and to demonstrate the performance and limitations of the system.
Acoustic centering of sources measured by surrounding spherical microphone arrays
Authors: Ben Hagai Ilan , Pollow Martin , Vorländer Michael , Rafaely Boaz
Published: October 2011

The radiation patterns of acoustic sources have great significance in a wide range of applications, such as measuring the directivity of loudspeakers and investigating the radiation of musical instruments for auralization. Recently, surrounding spherical microphone arrays have been studied for sound field analysis, facilitating measurement of the pressure around a sphere and the computation of the spherical harmonics spectrum of the sound source. However, the sound radiation pattern may be affected by the location of the source inside the microphone array, which is an undesirable property when aiming to characterize source radiation in a unique manner. This paper presents a theoretical analysis of the spherical harmonics spectrum of spatially translated sources and defines four measures for the misalignment of the acoustic center of a radiating source. Optimization is used to promote optimal alignment based on the proposed measures and the errors caused by numerical and array-order limitations are investigated. This methodology is examined using both simulated and experimental data in order to investigate the performance and limitations of the different alignment methods.
Passive acoustic survey of Yangtze finless porpoises using a cargo ship as a moving platform
Authors: Dong Lijun , Wang Ding , Wang Kexiong , Li Songhai , Dong Shouyue , Zhao Xiujiang , Akamatsu Tomonari , Kimura Satoko
Published: October 2011

In order to periodically investigate the population and distribution of the Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis) in its main distribution range in the Yangtze River, a passive acoustic system deployed on a cargo ship as a moving platform, rather than a dedicated research ship, was developed. A stereo acoustic event data-logger (A-tag) was installed on the cargo ship to passively detect phonating animals. In three surveys carried out in the Yangtze River from Wuhan to Shanghai, an average of 6059 clicks in each survey and 284 porpoises in total were acoustically detected along an 1100-km stretch. The animals were detected frequently in most of the survey range except two “gap sections” with 40 and 60 km lengths, respectively, where no animals were detected in all three surveys. Detected group sizes of the animals in each 120-s time window were not significantly different among the surveys, but the distribution pattern was different and suggested seasonal migration. The cargo ship based passive acoustic survey was effective in detecting phonating animals and can potentially monitor the distribution and population trend over time. Compared to surveys that used dedicated research ships, the present method is more cost effective.
A frequency selective acoustic transducer for directional Lamb wave Sensing
Authors: Senesi Matteo , Ruzzene Massimo
Published: October 2011

A frequency selective acoustic transducer (FSAT) is proposed for directional sensing of guided waves. The considered FSAT design is characterized by a spiral configuration in wavenumber domain, which leads to a spatial arrangement of the sensing material producing output signals whose dominant frequency component is uniquely associated with the direction of incoming waves. The resulting spiral FSAT can be employed both for directional sensing and generation of guided waves, without relying on phasing and control of a large number of channels. The analytical expression of the shape of the spiral FSAT is obtained through the theoretical formulation for continuously distributed active material as part of a shaped piezoelectric device. Testing is performed by forming a discrete array through the points of the measurement grid of a scanning laser Doppler vibrometer. The discrete array approximates the continuous spiral FSAT geometry, and provides the flexibility to test several configurations. The experimental results demonstrate the strong frequency dependent directionality of the spiral FSAT and suggest its application for frequency selective acoustic sensors, to be employed for the localization of broadband acoustic events, or for the directional generation of Lamb waves for active interrogation of structural health.
Modal parameters of two incomplete and complete guitars differing in the bracing pattern of the soundboard
Authors: Skrodzka Ewa , Łapa Andrzej , Linde Bogumił B. J. , Rosenfeld Eike
Published: October 2011

Similarities and differences in vibrational behavior of two guitars having a symmetric Torres bracing pattern and an asymmetric pattern forming a lattice on a soundboard are investigated by means of the modal analysis technique and laser Doppler vibrometry (LDV) measurements. Instruments are investigated before and after a bridge and strings assembling (i.e., they are incomplete or complete). The bracing pattern and the absence/presence of the bridge and strings have some effect on modal frequencies and mode shapes. The bracing pattern does not affect the sequence of at least first three low frequency mode shapes of incomplete/complete instruments but affects their modal frequencies. Depending on frequency, the bridge behaves either as a rigid or a flexible structure.
Phase calibration of sonar systems using standard targets and dual-frequency transmission pulses
Authors: Islas-Cital Alan , Atkins Philip R. , Foo Kae Y. , Picó Ruben
Published: October 2011

The phase angle component of the complex frequency response of a sonar system operating near transducer resonance is usually distorted. Interpretation and classification of the received sonar signal benefits from the preservation of waveform fidelity over the full bandwidth. A calibration process that measures the phase response in addition to the amplitude response is thus required. This paper describes an extension to the standard-target calibration method to include phase angle, without affecting the experimental apparatus, by using dual-frequency transmission pulses and frequency-domain data processing. This approach reduces the impact of unknown range and sound speed parameters upon phase calibration accuracy, as target phase is determined from the relationship of the two frequency components instead of relying on a local phase reference. Tungsten carbide spheres of various sizes were used to simultaneously calibrate the amplitude and phase response of an active sonar system in a laboratory tank. Experimental measurements of target phase spectra are in good agreement with values predicted from a theoretical model based upon full-wave analysis, over an operating frequency of 50–125 kHz.
Lateralization of acoustic signals by dichotically listening budgerigars (Melopsittacus undulatus)
Authors: Welch Thomas E. , Dent Micheal L.
Published: October 2011

Sound localization allows humans and animals to determine the direction of objects to seek or avoid and indicates the appropriate position to direct visual attention. Interaural time differences (ITDs) and interaural level differences (ILDs) are two primary cues that humans use to localize or lateralize sound sources. There is limited information about behavioral cue sensitivity in animals, especially animals with poor sound localization acuity and small heads, like budgerigars. ITD and ILD thresholds were measured behaviorally in dichotically listening budgerigars equipped with headphones in an identification task. Budgerigars were less sensitive than humans and cats, and more similar to rabbits, barn owls, and monkeys, in their abilities to lateralize dichotic signals. Threshold ITDs were relatively constant for pure tones below 4 kHz, and were immeasurable at higher frequencies. Threshold ILDs were relatively constant over a wide range of frequencies, similar to humans. Thresholds in both experiments were best for broadband noise stimuli. These lateralization results are generally consistent with the free field localization abilities of these birds, and add support to the idea that budgerigars may be able to enhance their cues to directional hearing (e.g., via connected interaural pathways) beyond what would be expected based on head size.
Elimination of standing wave effects in ultrasound radiation force excitation in air using random carrier frequency packets
Authors: Huber Thomas M. , Beaver Nathaniel M. , Helps Justin R.
Published: October 2011

The ultrasound radiation force has been used for noncontact excitation of devices ranging from microcantilevers to acoustic guitars. For ultrasound radiation force excitation, one challenge is formation of standing waves between the ultrasound transducer and the device under test. Standing waves result in constructive/destructive interference causing significant variations in the intensity of the ultrasound field. The standing-wave induced intensity variations in the radiation force can result from minor changes in the transducer position, carrier frequency, or changes in the speed of sound due to changes in ambient temperature. The current study demonstrates that by randomly varying the ultrasound carrier frequency in packets, it is possible to eliminate the negative consequences resulting from the formation of standing waves. A converging ultrasound transducer with a central frequency of 550 kHz was focused onto a brass cantilever. The 267 Hz resonance was excited with the ultrasound radiation force with a carrier frequency that randomly varied between 525 kHz to 575 kHz in packets of 10 cycles. Because each packet had a different carrier frequency, the amplitude of standing wave artifacts was reduced by a factor of 20 compared to a constant frequency excitation of 550 kHz.
Estimation of mechanical properties of a viscoelastic medium using a laser-induced microbubble interrogated by an acoustic radiation force
Authors: Yoon Sangpil , Aglyamov Salavat R. , Karpiouk Andrei B. , Kim Seungsoo , Emelianov Stanislav Y.
Published: October 2011

An approach to assess the mechanical properties of a viscoelastic medium using laser-induced microbubbles is presented. To measure mechanical properties of the medium, dynamics of a laser-induced cavitation microbubble in viscoelastic medium under acoustic radiation force was investigated. An objective lens with a 1.13 numerical aperture and an 8.0 mm working distance was designed to focus a 532 nm wavelength nanosecond pulsed laser beam and to create a microbubble at the desired location. A 3.5 MHz ultrasound transducer was used to generate acoustic radiation force to excite a laser-induced microbubble. Motion of the microbubble was tracked using a 25 MHz imaging transducer. Agreement between a theoretical model of bubble motion in a viscoelastic medium and experimental measurements was demonstrated. Young’s modulii reconstructed using the laser-induced microbubble approach were compared with those measured using a direct uniaxial method over the range from 0.8 to 13 kPa. The results indicate good agreement between methods. Thus, the proposed approach can be used to assess the mechanical properties of a viscoelastic medium.
Native dialect matters: Perceptual assimilation of Dutch vowels by Czech listeners
Authors: Chládková Kateřina , Jonáš Podlipský Václav
Published: October 2011

Naive listeners’ perceptual assimilations of non-native vowels to first-language (L1) categories can predict difficulties in the acquisition of second-language vowel systems. This study demonstrates that listeners having two slightly different dialects as their L1s can differ in the perception of foreign vowels. Specifically, the study shows that Bohemian Czech and Moravian Czech listeners assimilate Dutch high front vowels differently to L1 categories. Consequently, the listeners are predicted to follow different paths in acquiring these Dutch vowels. These findings underscore the importance of carefully considering the specific dialect background of participants in foreign- and second-language speech perception studies.
Accounting for the stability of microbubbles to multi-pulse excitation using a lipid-shedding model
Authors: O’Brien Jean-Pierre , Ovenden Nick , Stride Eleanor
Published: October 2011

Interest in microbubble ultrasound contrast agents as therapeutic and quantitative imaging tools has increased the need for accurate modeling of their behavior. Experiments have shown that some bubbles shrink significantly over the course of a single pulse but that the bubbles may eventually reach a stable size after many insonations. Here, it is shown from dimensional arguments that diffusion phenomena are negligible on the time scales that characterize a typical ultrasound pulse. Subsequently, a new model describing both a lipid-shedding mechanism and a nonlinear surface viscosity is developed and shown to provide a more accurate description of the observed experimental behavior.
Statistics of the envelope of ultrasonic backscatter from human trabecular bone
Authors: Litniewski Jerzy , Cieslik Lucyna , Wojcik Janusz , Nowicki Andrzej
Published: October 2011

The paper describes the investigations intended to compare the results of experimental measurements of backscattering properties of the trabecular bone with the results of computer simulations. Ultrasonic RF echoes were collected using two bone scanners operating at 0.58 and 1.3 MHz. The simulations of the backscattered RF echoes were performed using the scattering model of the trabecular bone that consisted of cylindrical and spherical elements uniformly distributed in water-like medium. For each measured or simulated RF backscatter the statistical properties of the signal envelope were determined. Experimental results suggest deviations of the backscattering properties from the Rayleigh distribution. The results of simulation suggest that deviation from Rayleigh distribution depends on the variation of trabeculae diameters and the number of thin trabeculae. Experimentally determined deviations corresponded well to the deviations calculated from simulated echoes assuming trabeculae thickness variation equaled to the earlier published histomorphometric study results.
Fundamental frequency is critical to speech perception in noise in combined acoustic and electric hearing
Authors: Carroll Jeff , Tiaden Stephanie , Zeng Fan-Gang
Published: October 2011

Cochlear implant (CI) users have been shown to benefit from residual low-frequency hearing, specifically in pitch related tasks. It remains unclear whether this benefit is dependent on fundamental frequency (F0) or other acoustic cues. Three experiments were conducted to determine the role of F0, as well as its frequency modulated (FM) and amplitude modulated (AM) components, in speech recognition with a competing voice. In simulated CI listeners, the signal-to-noise ratio was varied to estimate the 50% correct response. Simulation results showed that the F0 cue contributes to a significant proportion of the benefit seen with combined acoustic and electric hearing, and additionally that this benefit is due to the FM rather than the AM component. In actual CI users, sentence recognition scores were collected with either the full F0 cue containing both the FM and AM components or the 500-Hz low-pass speech cue containing the F0 and additional harmonics. The F0 cue provided a benefit similar to the low-pass cue for speech in noise, but not in quiet. Poorer CI users benefited more from the F0 cue than better users. These findings suggest that F0 is critical to improving speech perception in noise in combined acoustic and electric hearing.
Phase-controlling phononic crystals: Realization of acoustic Boolean logic gates
Authors: Bringuier S. , Swinteck N. , Vasseur J. O. , Robillard J.-F. , Runge K. , Muralidharan K. , Deymier P. A.
Published: October 2011

A phononic crystal (PC) consisting of a square array of cylindrical Polyvinylchloride inclusions in air is used to construct a variety of acoustic logic gates. In a certain range of operating frequencies, the PC band structure shows square-like equi-frequency contours centered off the Gamma point. This attribute allows for the realization of non-collinear wave and group velocity vectors in the PC wave vector space. This feature can be utilized to control with great precision, the relative phase between propagating acoustic waves in the PC. By altering the incidence angle of the impinging acoustic beams or varying the PC thickness, interferences occur between acoustic wave pairs. It is recognized that information can be encoded with this mechanism (e.g., wave amplitudes/interference patterns) and accordingly to construct a series of logic gates emulating Boolean functions. The NAND, XOR, and NOT gates are demonstrated with finite-difference time-domain simulations of acoustic waves impinging upon the PC.
Masker location uncertainty reveals evidence for suppression of maskers in two-talker contexts
Authors: Allen Kachina , Alais David , Shinn-Cunningham Barbara , Carlile Simon
Published: October 2011

In many natural settings, spatial release from masking aids speech intelligibility, especially when there are competing talkers. This paper describes a series of three experiments that investigate the role of prior knowledge of masker location on phoneme identification and spatial release from masking. In contrast to previous work, these experiments use initial stop-consonant identification as a test of target intelligibility to ensure that listeners had little time to switch the focus of spatial attention during the task. The first experiment shows that target phoneme identification was worse when a masker played from an unexpected location (increasing the consonant identification threshold by 2.6 dB) compared to when an energetically very similar and symmetrically located masker came from an expected location. In the second and third experiments, target phoneme identification was worse (increasing target threshold levels by 2.0 and 2.6 dB, respectively) when the target was played unexpectedly on the side from which the masker was expected compared to when the target came from an unexpected, symmetrical location in the hemifield opposite the expected location of the masker. These results support the idea that listeners modulate spatial attention by both focusing resources on the expected target location and withdrawing attentional resources from expected locations of interfering sources.
Developmental changes in ultrasonic vocalizations by infant Japanese echolocating bats, Pipistrellus abramus
Authors: Hiryu Shizuko , Riquimaroux Hiroshi
Published: October 2011

Developmental changes in vocalizations by Pipistrellus abramus were investigated during the first post-natal month. Vocalizations by pups on the day of birth were frequency-modulated ultrasounds from 30.0 ± 4.0 kHz to 19.3 ± 1.9 kHz with multiple harmonics. The terminal frequency of the second harmonic (TF2) of pup vocalizations corresponded to that of the fundamental (TF1) in adult bats (41.4 ± 2.6 kHz), suggesting that pup vocalizations can be easily detected by the mother. In addition, there are two types of infant vocalization: short duration echolocation precursor and long duration isolation calls, which showed separate developmental patterns over time.
Relating the performance of time-reversal-based underwater acoustic communications in different shallow water environments
Authors: Yang T. C.
Published: October 2011

The performance of underwater acoustic communications, such as the output signal-to-noise ratio (OSNR), is generally dependent on the channel specifics, hence a channel model is normally required as the performance of the channel equalizer depends on the number of tap coefficients used (e.g., a sparse equalizer) which are different for different oceans having different multipath arrivals. This letter presents theoretical arguments, and experimental data from different oceans that suggest that the increase of OSNR with the number of diverse receivers (in terms of the effective number of receivers) and the decrease of OSNR with the channel-estimation error follow a universal relationship using the time-reversal or correlation-based equalizer, despite the fact that the channels have very different properties. The reason is due to the fact that the OSNR is a function of the q function, the auto-correlation of the received impulse responses summed over all receiver channels, and the q function is approximately the same for all shallow waters given a sufficient (≥4 − 6) number of receivers.
Stochastic channel simulator based on local scattering functions
Authors: Isukapalli Y. , Song H. C. , Hodgkiss W. S.
Published: October 2011

This letter addresses the limitations of the stochastic channel simulation approach employed in wireless channels when directly applied to underwater channels. First it is shown analytically why the simulation method fails when the correlated taps each have a different Doppler spectrum. Then, based on the idea of local scattering functions, we propose a simple solution to the problem of simulating a channel with correlated taps where the correlated taps occur in subgroups with each of the subgroups having a different Doppler spectrum, applicable to underwater channels. Our simulation approach is tested successfully on the KAM08 channel.
Effects of roving level and spectral range on vowel formant discrimination
Authors: Liu Chang
Published: October 2011

Thresholds of vowel formant discrimination for F1 and F2 of isolated vowels with full and partial vowel spectra were measured for normal-hearing listeners at fixed and roving speech levels. Performance of formant discrimination was significantly better for fixed levels than for roving levels with both full and partial spectra. The effect of vowel spectral range was present only for roving levels, but not for fixed levels. These results, consistent with studies of profile analysis, indicated different perceptual mechanisms for listeners to discriminate vowel formant frequency at fixed and roving levels.
Probing the interior of a solid volume with time reversal and nonlinear elastic wave spectroscopy
Authors: Le Bas P. Y. , Ulrich T. J. , Anderson B. E. , Guyer R. A. , Johnson P. A.
Published: October 2011

A nonlinear scatterer is simulated in the body of a sample and demonstrates a technique to locate and define the elastic nature of the scatterer. Using the principle of time reversal, elastic wave energy is focused at the interface between blocks of optical grade glass and aluminum. Focusing of energy at the interface creates nonlinear wave scattering that can be detected on the sample perimeter with time-reversal mirror elements. The nonlinearly generated scattered signal is bandpass filtered about the nonlinearly generated components, time reversed and broadcast from the same mirror elements, and the signal is focused at the scattering location on the interface.
STATISTICAL FEATURE-BASED CRAQUELURE CLASSIFICATION
Authors: CRISOLOGO IRENE , MONTEROLA CHRISTOPHER , SORIANO MARICOR
Published: October 2011

We demonstrate an automatic procedure for extracting features such as directionality of crack patterns, distribution of node distances and segment lengths, fractal dimension, entropy, and crack coverage to aid in automatic classification of painting cracks or craquelures. To test our classifier, we make use of four distinct craquelure patterns, designated by names based on their country of origin, namely: Dutch, Flemish, French or Italian. We report that selecting features based on effect size ratio from the above statistical measures, the standard linear discriminant analysis (LDA) can make predictive classification of the craquelure patterns with a 69.4% accuracy. Effect size ratio simultaneously quantifies the extent of correlation and variance of two statistical sets of data. This test set accuracy is more than two times better than mere chance classification, or the proportional chance criterion, computed to be ΦPCC= 27.61% and also twice the recommended classifier accuracy 1.25 × ΦPCC= 34.4%. We compare the result with the nonlinear method of neural network and we observe no marked improvement in the resulting accuracy. This suggests that the problem at hand with respect to the statistical features extracted is a linear classification problem. The work provides a comprehensive guide on the algorithms that can be used to extract quantitative information of crack patterns.
SOLUBLE POLYMER DIRECTED CONTROLLED SYNTHESIS OF GOLD NANOPARTICLES: EFFECT OF CLOUD POINT, REDUCING AGENT, AND MIXING METHOD ON NANOPARTICLES PREPARATION
Authors: SHERVANI ZAMEER , YAMAMOTO YASUSHI
Published: October 2011

Au(0) metallic nanoparticles (Au NPs) were first prepared in triblock copolymer poly (methyl vinyl ether) PMVE-water dispersions. The wax formed from cloud point appearance in PMVE (0.6 wt.%)-water on heating the solution at 40°C worked as a template to trap the reduced Au NPs of 3 nm (σ = 0.8) size. Cooling the solution to 25°C, the cloud point disappeared as a result the particles aggregated to larger oval shape crystals with major and minor diameters 99.5 nm (σ = 4.5) and 84 nm (σ = 2), respectively when solution was stirred for one week for the completion of reaction. Smaller (4.4. nm (σ = 1.2)) particles were obtained when Au salt HAuCl4⋅3H2O (hydrogen tetrachloroaurate (III) trihydrate) was reduced by 5 equivalents of NaBH4 , whereas the addition of 10 equivalents NaOH gave larger particles of 13 nm (σ = 2.4) diameter. PMVE polymer alone acted as a reducing and stabilizing agent but the time of completion of reduction was much longer (one week) compared to the reduction conducted by NaBH4 or NaOH where the reaction completed in 15 min. In neat PMVE polymer-water dispersions a number of mixing methods employed to reduce Au salt followed the order: combination of sonication and stirring > sonication > stirring. Au NPs formation was 27%, 21%, and 5%, respectively in 4 h of reaction time. The mixing experiments justified the development of microchannel mixers for NPs production on a large scale.
AB INITIO CALCULATIONS AND KINETICS STUDY FOR THE DIRECT HYDROGEN ABSTRACTION REACTION OF HYDROGEN SELENIDE WITH HYDROGEN ATOM
Authors: ZHANG YUE
Published: October 2011

We present a direct ab initio dynamics study of thermal rate constants of the hydrogen abstraction reaction of H 2 Se + H → SeH + H 2. The QCISD and CCSD(T) methods were employed to optimize the geometries of stationary points and to calculate the harmonic vibrational frequencies. The split-valence 6-311 + G(d,p) and correlation-consistent cc-pVTZ basis sets big enough to describe the geometries and vibrational frequencies of the species involving in the title reaction. The energies obtained at the QCISD(T)/6-311 ++ G(3df,3pd)//QCISD/6-311 + G(d,p) level of theory is able to compare to those calculated at the CCSD(T)/6-311 ++ G(3df,3pd)//CCSD(T)/6-311 + G(d,p) level of theory. The energies of all the selected points along the minimum energy path (MEP) were refined at the QCISD(T)/6-311 ++ G(3df,3pd) level of theory. The barriers were obtained at the both QCISD(T)/6-311 ++ G(3df,3pd)//QCISD/6-311 + G(d,p) and CCSD(T)/6-311 ++ G(3df,3pd)//CCSD(T)/6-311 + G(d,p) levels of theory are in good agreement with experimental one. The forward rate constants were evaluated with both canonical variational transition state theory with small curvature tunneling correction (CVT/SCT) and improved canonical variational transition state theory with small curvature tunneling correction (ICVT/SCT) in the temperature range of 200–2500 K. The calculated forward rate constants of the reaction at the QCISD(T)/6-311 ++ G(3df,3pd)//QCISD/6-311 + G(d,p) level of theory are in good agreement with available experimental data.
THE VALUE OF NETWORKING IN 21st CENTURY HIGHER EDUCATION: THE MARNE-LA-VALLÉE UNIVERSITY CASE
Authors: POCE ANTONELLA
Published: October 2011

The keyword that most effectively describes 21st-century higher education is "expansion," as suggested by Daniel et al. [2009]. The present contribution aims to analyze current higher education requirements, offers a general insight into how to respond to pressing needs by exploiting the added value of networking potentiality, and reports on a successful case: the Licence Professionnelle "Management des Organisations de l'Economie Sociale" course (University Marne-la-Vallée, France).
SECURE SEMANTIC COMPUTING
Authors: HAMLEN KEVIN W. , THURAISINGHAM BHAVANI
Published: October 2011

This paper explores the integration of semantic computing technologies with security technologies. Past and current research on the application of semantic web technologies for policy management and inference control, the application of data mining technologies for intrusion and malware detection, and programming language-based approaches to mobile code certification and data confidentiality enforcement are discussed.
Unsupervised 3D Prostate Segmentation Based on Diffusion-Weighted Imaging MRI Using Active Contour Models with a Shape Prior
Authors: Liu Xin , Haider Masoom A. , Yetik Imam Samil
Published: October 2011

Accurate estimation of the prostate location and volume fromin vivoimages plays a crucial role in various clinical applications. Recently, magnetic resonance imaging (MRI) is proposed as a promising modality to detect and monitor prostate-related diseases. In this paper, we propose an unsupervised algorithm to segment prostate with 3D apparent diffusion coefficient (ADC) images derived from diffusion-weighted imaging (DWI) MRI without the need of a training dataset, whereas previous methods for this purpose require training datasets. We first apply a coarse segmentation to extract the shape information. Then, the shape prior is incorporated into the active contour model. Finally, morphological operations are applied to refine the segmentation results. We apply our method to an MR dataset obtained from three patients and provide segmentation results obtained by our method and an expert. Our experimental results show that the performance of the proposed method is quite successful.
Acute Pancreatitis Complicated with Choledochal Duct Rupture
Authors: Bouvry M. , Van Renterghem K. , Verrijckt A. , Smeets P. , Meersschaut V. , Vande Velde S. , De Bruyne R. , De Vos M. , Van Winckel M. , Van Biervliet S.
Published: October 2011

Recurrent acute pancreatitis is a rare clinical entity in childhood with unknown incidence (Rosendahl et al., 2007) and often occurring in a familial context. Genetic factors such as PRSS1 mutations (cationic trypsinogen gene) can be found in some patients. However, many remain idiopathic. The natural history remains poorly documented and the most frequent complications reported are pain, exocrine pancreatic insufficiency, diabetes mellitus, and pancreatic adenocarcinoma after long-standing hereditary pancreatitis. We describe a patient with hereditary pancreatitis in whom a mild pancreatitis episode was complicated by a perforation of the ductus choledochus.
Developmental and Cognitive Characteristics of “High-Level Potentialities” (Highly Gifted) Children
Authors: Vaivre-Douret Laurence
Published: October 2011

This study covers the interesting field of the development in gifted children which is often neglected in pediatrics because psychomotor development data are still rare, since “gifted” children are generally noticed towards the end of their primary schooling by IQ measurement. Developmental studies have shown the evidence from several fields that children identified as “high-level potentialities” or “intellectually gifted” develop sensory, locomotor, neuropsychological, and language skills earlier than typically expected. The hypothesis is offered that the earlier development originates from biological processes affecting the physical development of the brain and in turn even intellectual abilities are developed earlier, potentially allowing for advanced development. Further it is discussed how these developmental advances interact with the social environment and in certain circumstances may entail increased risk for developing socioemotional difficulties and learning disabilities that often go unaddressed due to the masking by the advance intellectual abilities.
A Modal Description of Multiport Antennas
Authors: Lynch Jonathan J.
Published: October 2011

This paper presents a modal description of multiport antennas that leads directly to a rigorous network representation and simple quadratic expressions for gain, efficiency, and effective area. The analysis shows that the transmitting and receiving properties of an element antenna array are exactly described by a element scattering matrix together with a set of orthonormal mode functions and accounts for effects such as mutual coupling, scattering, reflection, and losses. The approach is quite general, only requiring that the antenna be finite and reciprocal. The scattering network description simplifies accounting of power flow while retaining a close connection to the physical antenna characteristics. The orthonormal mode functions provide a complete basis for radiated and received fields, facilitating beamforming. The theory provides rigorous definitions of input-output signals and links them to the underlying electromagnetics in a straightforward manner.
A Cache Architecture for Counting Bloom Filters: Theory and Application
Authors: Ahmadi Mahmood , Wong Stephan
Published: October 2011

Within packet processing systems, lengthy memory accesses greatly reduce performance. To overcome this limitation, network processors utilize many different techniques, for example, utilizing multilevel memory hierarchies, special hardware architectures, and hardware threading. In this paper, we introduce a multilevel memory architecture for counting Bloom filters. Based on the probabilities of incrementing of the counters in the counting Bloom filter, a multi-level cache architecture called the cached counting Bloom filter (CCBF) is presented, where each cache level stores the items with the same counters. To test the CCBF architecture, we implement a software packet classifier that utilizes basic tuple space search using a 3-level CCBF. The results of mathematical analysis and implementation of the CCBF for packet classification show that the proposed cache architecture decreases the number of memory accesses when compared to a standard Bloom filter. Based on the mathematical analysis of CCBF, the number of accesses is decreased by at least 53%. The implementation results of the software packet classifier are at most 7.8% (3.5% in average) less than corresponding mathematical analysis results. This difference is due to some parameters in the packet classification application such as number of tuples, distribution of rules through the tuples, and utilized hashing functions.
Bimetallic Pt-Ru Nanoparticle Catalyst for Hydrogen Peroxide Detection
Authors: Janyasupab Metini , Zhang Yuan , Lin Po-Yuan , Bartling Brandon , Xu Jiaqiang , Liu Chung-Chiun
Published: October 2011

A bimetallic Pt-Ru nanoparticle catalyst was prepared and characterized for the enhancement of hydrogen peroxide (H2O2) detection in biosensing applications. The particles were synthesized via sodium borohydride reduction, with low heat treatment, and characterized by TEM and HRTEM. The chemical composition analyses were performed by EDX. The bimetallic particle diameters ranged from 2 to 12 nm, with an average of 4.5 nm. The Pt-Ru catalyst exhibited an improved performance at low overpotential (+0.2 V versus Ag/AgCl reference electrode) in H2O2detection, suggesting a sensitivity value of 78.95 μA⋅mM-1(or 402.1 μA⋅mM-1⋅cm-2) which was 30% higher than that for the single Pt catalyst. The major contribution of this enhancement comes from the stronger oxygen adsorption on Ru metal. The Pt-Ru catalyst also showed a more stable signal at the high overpotential (+0.4 V versus Ag/AgCl), providing better accuracy in the detection of H2O2.
Distinct Effects of Calorie Restriction and Resveratrol on Diet-Induced Obesity and Fatty Liver Formation
Authors: Tauriainen Eveliina , Luostarinen Mira , Martonen Essi , Finckenberg Piet , Kovalainen Miia , Huotari Anne , Herzig Karl-Heinz , Lecklin Anne , Mervaala Eero
Published: October 2011

The potential of resveratrol to mimic beneficial effects of calorie restriction (CR) was investigated. We compared the effects of both CR (70% ofad libitumenergy intake) or resveratrol (2 g/kg or 4 g/kg food) on high-fat diet-induced obesity and fatty liver formation in C57Bl/6J mice, and we examined their effects on calorimetry, metabolic performance, and the expressions of inflammatory genes and SIRT proteins. We found that resveratrol with 4 g/kg dose partially prevented hepatic steatosis and hepatocyte ballooning and induced skeletal muscle SIRT1 and SIRT4 expression while other examined parameter were unaffected by resveratrol. In contrast, CR provided superior protection against diet-induced obesity and fatty liver formation as compared to resveratrol, and the effects were associated with increased physical activity and ameliorated adipose tissue inflammation. CR increased expressions of SIRT3 in metabolically important tissues, suggesting that the beneficial effects of CR are mediated, at least in part, via SIRT3-dependent pathways.
Novel Stromal Biomarkers in Human Breast Cancer Tissues Provide Evidence for the More Malignant Phenotype of Estrogen Receptor‐Negative Tumors
Authors: Khamis Zahraa I. , Sahab Ziad J. , Byers Stephen W. , Sang Qing-Xiang Amy
Published: October 2011

Research efforts were focused on genetic alterations in epithelial cancer cells. Epithelial‐stromal interactions play a crucial role in cancer initiation, progression, invasion, angiogenesis, and metastasis; however, the active role of stroma in human breast tumorigenesis in relation to estrogen receptor (ER) status of epithelial cells has not been explored. Using proteomics and biochemical approaches, we identified two stromal proteins in ER‐positive and ER‐negative human breast cancer tissues that may affect malignant transformation in breast cancer. Two putative biomarkers, T‐cell receptor alpha (TCR‐α) and zinc finger and BRCA1‐interacting protein with a KRAB domain (ZBRK1), were detected in leukocytes of ER‐positive and endothelial cells of ER‐negative tissues, respectively. Our data suggest an immunosuppressive role of leukocytes in invasive breast tumors, propose a multifunctional nature of ZBRK1 in estrogen receptor regulation and angiogenesis, and demonstrate the aggressiveness of ER‐negative human breast carcinomas. This research project may identify new stromal drug targets for the treatment of breast cancer patients.
Upregulated Expression of Cytotoxicity‐Related Genes in IFN‐γ Knockout Mice with Schistosoma japonicum Infection
Authors: Du Xiaotang , Wu Jingjiao , Zhang Meijuan , Gao Yanan , Zhang Donghui , Hou Min , Ji Minjun , Wu Guanling
Published: October 2011

It is well accepted that IFN‐γ is important to the development of acquired resistance against murine schistosomiasis. However, the in vivo role of this immunoregulatory cytokine in helminth infection needs to be further investigated. In this study, parasite burden and host immune response were observed in IFN‐γ knockout mice (IFNg KO) infected with Schistosoma japonicum for 6 weeks. The results suggested that deficiency in IFN‐γ led to decreased egg burden in mice, with low schistosome‐specific IgG antibody response and enhanced activation of T cells during acute infection. Microarray and qRT‐PCR data analyses showed significant upregulation of some cytotoxicity‐related genes, including those from the granzyme family, tumor necrosis factor, Fas Ligand, and chemokines, in the spleen cells of IFNg KO mice. Furthermore, CD8+ cells instead of NK cells of IFNg KO mice exhibited increased transcription of cytotoxic genes compared with WT mice. Additionally, Schistosoma japonicum‐specific egg antigen immunization also could activate CD8+ T cells to upregulate the expression of cytotoxic genes in IFNg KO mice. Our data suggest that IFN‐γ is not always a positive regulator of immune responses. In certain situations, the disruption of IFN‐γ signaling may up‐regulate the cytotoxic T‐cell‐mediated immune responses to the parasite.
Figs Are More Than Fallback Foods: The Relationship betweenFicusandCebusin a Tropical Dry Forest
Authors: Parr Nigel A. , Melin Amanda D. , Fedigan Linda Marie
Published: October 2011

In many studies on primate feeding ecology, figs (Ficusspp.) are characterized as fallback foods, utilized only when preferred sources of food are unavailable. However, for white-faced capuchin monkeys (Cebus capucinus) living in northwestern Costa Rica, figs are a consistently important resource and may increase groupwide energy intake. We investigated whether visits to figs affect ranging and behavioural patterns of capuchins. Although daily range length and average travel speed do not differ on days when fig trees are visited, capuchins spend more time in directed travel and more time stationary on “fig days”. Capuchins also increase time spent foraging for fruit and decrease time spent foraging for invertebrates on days when figs trees are visited. Capuchins experience higher energy intake and lower energy output on “fig” days. Thus, the patterns of foraging for figs support an energy-maximization strategy and constitute an important nutritional resource for capuchins.