bluuebunny/crossref_metadata_2025 huggingface dataset:
Measured and predicted array response to the vertical directivity of ambient noise
Authors: Holden Andrew
Published: October 2013

A great deal has been published on ambient noise. Most of this has covered (a) omni directional levels, and (b) the vertical and horizontal directivity of shipping noise at low frequencies. There is some published material on the vertical directivity of wind generated noise at lower frequencies, but very little at higher frequencies. In order to study wind generated ambient noise at higher frequencies, a small planar array from QinetiQ Bincleaves has been used to make ambient noise measurements. As well as measurements, a model called CANARY has been written to predict ambient noise vertical directivity and array responses to this noise. This paper contains some comparisons between CANARY predictions and (a) previously measured array response to ambient noise vertical directivity at 4.5 kHz, and (b) analysis of the planar array measurements at 25 kHz. The paper shows the nature of the ambient noise vertical structure and that the CANARY predictions are in good agreement with the measurements.
Simulation of synthetic aperture sonar performance under experimentally measured environmental fluctuations
Authors: Ruppel Timothy H. , Stanic Steve
Published: October 2013

In June 2003, NRL conducted a series of coherence measurements in very shallow water (8 m depth) off the coast of Panama City, FL under a wide range of ocean conditions. Low-frequency (1–10 kHz) and high-frequency (10–200 kHz) measurements were taken. The results show appreciable variability even during fairly calm conditions. This paper will report on the effects of this experimentally measured variability on the performance of a simple computer-simulated synthetic aperture sonar (SAS). SAS works by rapidly and repeatedly pinging a target from a moving acoustic array platform. If the underwater acoustic environment changes appreciably between pings, random phase errors are introduced on the individual SAS receiving elements, with the result that the SAS image might be significantly degraded. The use of a computer-modeled SAS allows for the investigation of these effects in the absence of such phenomena as random receiver motion (motion compensation) or specific auto-focusing algorithms. [Work supported by the ONR Program Element No. 62435N.]
Scale-model studies of reverberant energy decay in a coupled-room system
Authors: Summers Jason E. , Torres Rendell R. , Shimizu Yasushi
Published: October 2013

Energy decay at high, middle, and low frequencies is measured in a reconfigurable 1:10 scale model of a two-room coupled system schematically representing a coupled-room concert hall. Measurements are used both to phenomenologically characterize decay behavior in each frequency range and to validate analytical and computational models. At high frequencies, decay behavior is characteristic of energy exchange between diffuse fields. Comparisons of computational geometrical-acoustics predictions based on randomized beam-axis tracing with scale-model measurements indicate errors resulting from tail-correction assuming constant quadratic growth of reflection density. Using ray tracing in the late part in place of tail correction is shown to correct this error. At midfrequencies, scattering at apertures results in dependence of decay behavior on aperture shape. High-frequency geometrical-acoustics and statistical-acoustics models are modified to account for wave effects at coupling apertures by including power transmission coefficients of apertures [J. E. Summers et al., J. Acoust. Soc. Am. 112, 2226 (A) (2002)]. Scale-model measurements evidence behavior predicted by these models. At low frequencies, coupling strength is related to unperturbed pressure distribution on coupling surfaces. Perturbation models [C. M. Harris and H. Feshbach, J. Acoust. Soc. Am. 22, 572–578 (1950)] qualitatively explain these effects. [Work supported by the Bass Foundation.] a)Current address: Acoustics Division, Naval Research Laboratory, Washington, DC 20375-5350.
Analysis of multipath acoustic field variability and coherence in the finale of broadband basin-scale transmissions in the North Pacific Ocean
Authors: Colosi John
Published: October 2013

The statistics of low-frequency, long-range acoustic transmissions in the North Pacific Ocean are presented. Broadband signals at center frequencies of 28, 75, and 84 Hz are analyzed at propagation ranges of 3252 to 5171 km, and transmissions were received on 700- and 1400-m-long vertical receiver arrays with 35-m hydrophone spacing. The analysis focuses on the energetic ‘‘finale’’ region of the broadband timefront arrival pattern where a multipath interference pattern exists. Two-dimensional (depth and time) phase unwrapping is employed to study separately the complex field phase and intensity.
Variation in acoustic detection distances of delphinid whistles using a towed hydrophone array in several geographic areas
Authors: Oswald Julie N. , Rankin Shannon , Barlow Jay
Published: October 2013

Dolphins were detected using a towed hydrophone array during cetacean abundance surveys in the eastern tropical Pacific (ETP) and in U.S. west coast waters up to 300 nmi offshore (USWC). Cross-correlation algorithms were used to estimate bearing angles to vocalizing dolphins. The convergence of bearing angles as the ship traveled indicated the probable location of dolphins. The study areas were stratified based on sound speed profiles, sea surface temperature, and depth of the thermocline to examine the effect of oceanographic conditions on acoustic detection distances (the greatest distance at which bearing angles can be determined) for delphinid whistles. Significant differences in mean detection distances were found between offshore ETP (2.9 nmi) and USWC waters (1.5 nmi, p<0.001), and between USWC waters and waters off Peru and Baja pooled (2.9 nmi, p=0.005). Ray trace models confirm these empirical differences in acoustic propagation. Results suggest that the effectiveness of acoustic methods during cetacean abundance surveys varies with oceanographic conditions. Regional variability in whistle propagation may partially explain why whistles are seldom or never used by some northern delphinid species but are commonly used by virtually all tropical delphinid species.
Axisymmetric acoustic radiation from submerged prolate spheroidal shells
Authors: Boisvert Jeffrey E. , Hayek Sabih I.
Published: October 2013

The equations of motion for nonaxisymmetric vibration of prolate spheroidal shells of constant thickness were derived using Hamiltons principle [S. I. Hayek and J. E. Boisvert, J. Acoust. Soc. Am. 114, 2799–2811 (2003)]. The shell theory used in this derivation includes shear deformations and rotatory inertias. The shell displacements and rotations were expanded in infinite series of comparison functions. These include associated Legendre functions in terms of the prolate spheroidal angular coordinate and circular functions in the azimuthal angle coordinate. For axisymmetric vibration of a submerged shell, the external (heavy) fluid loading impedance was computed using expansions of prolate spheroidal wavefunctions. The shell was excited by axisymmetric normal surface forces, including a point load at the shell apex and ring load at other locations. Far-field radiated pressure spectra are presented for several shell thickness-to-half-length ratios ranging from 0.005 to 0.1, and for various shape parameters, a, ranging from an elongated spheroidal shell (a=1.01) to a spherical shell (a∼100). The far-field directivity of acoustic radiation is presented at selected frequencies. [Work supported by the NUWC ILIR Program and the ONR/ASEE Summer Faculty Research Program.]
Damage detection in composites using the time-reversal acoustics method
Authors: Sutin Alexander , Roides Eric , Sarvazyan Armen
Published: October 2013

Time-reversal acoustics (TRA) can provide focusing of broadband frequency pulses in complex structures where different types of elastic waves can propagate. In this work, TRA focusing efficacy in the presence of mechanical damage in a material to test the integrity of various composites has been explored. The experiments were conducted on the following materials: (1) Static and cyclic loaded composite samples made of Grade 11 Garolite. (2) A Garolite plate with local damages created by an air gun bullet. (3) Epoxy/carbon fiber composites with mechanical damage. Experiment results demonstrated that a TRA focused signal passing through a damaged area has a greater level of distortion. This effect is manifested in the shape of a waveform of the TRA focused signal. In the presence of the defect, the density of the acoustic energy in the TRA focused waveform redistributes, decreasing in the center and increasing at the sides. The distortion of the TRA focused signal was significant for the composite samples affected by cyclic loading even when there were no visible defects. [Work supported by NASA.]
CFD simulation of deflection of a jet emerging from organ pipe flue
Authors: Adachi Seiji
Published: October 2013

The phenomenon of an air jet deflected by sound is the crucial element in the sounding principle of air-jet driven instruments. Currently, the jet deflection model proposed by Fletcher is most widely accepted. This model successfully predicts basic properties of the instrument such as overblowing behavior with a change in blowing pressure. However, a gap still exists between the actual behavior and that predicted by the model. This gap is probably due to the model’s conceptual approximations, such as an inviscid fluid and a linear response of the deflection amplitude to the magnitude of the sound field. This research aims to develop a jet deflection model directly from the Navier–Stokes equations, which govern all flow-related phenomena. Therefore, computational fluid dynamical (CFD) simulation of a jet emerging from a flue slit and deflected by the external sound field was carried out. The results were analyzed to obtain the velocity profile of the jet, the phase delay, and the magnitude of the jet deflection amplitude. The overblowing behavior estimated from the analysis is discussed by comparing it with that actually observed.
Statistical automatic species identification of microchiroptera from echolocation calls: Lessons learned from human automatic speech recognition
Authors: Skowronski Mark D. , Harris John G.
Published: October 2013

Current automatic species identification of microchiroptera through echolocation search calls utilizes holistic features, such as call duration, bandwidth, and frequency extrema, which stem from expert knowledge of sonograms of individual calls. This approach parallels the early acoustic-phonetic paradigm of human automatic speech recognition (ASR), which relied heavily on expert knowledge to account for variations in canonical linguistic units of interest. Acoustic-phonetic ASR gave way to the statistical paradigm of ASR primarily because of the superior ability of machine learning to account for variations in the acoustic signal (noise, speaker characteristics) [Juang and Furui, Proc. IEEE 88 (8), 1142–1165 (2000)]. In the current work, machine learning methods from human ASR, hidden Markov models (HMM) and dynamic time warping (DTW), are considered for the problem of automatic species identification of microchiroptera from echolocation calls. The extensive history of ASR provides valuable lessons, which are highlighted and applied to species recognition from field-recorded acoustic data. Frame-based features of the acoustic signal (fundamental frequency, log energy, temporal derivatives) are incorporated into HMM and DTW classifiers, and experimental results indicate the superior approach of statistical automatic species identification compared to current techniques.
Psychophysical evidence for the existence of envelope information in the internal auditory representation of signal fine structure
Authors: Apoux Frederic , Millman Rebecca E. , Brown Christopher A. , Bacon Sid P. , Viemeister Neal F.
Published: October 2013

This study examined the extent to which the auditory system can recover envelope information from phase information contained in signal fine structure [O. Ghitza, J. Acoust. Soc. Am. 110, 1628–1640 (2001)]. A 2IFC paradigm was used to assess amplitude modulation (AM) detection performance for stimuli whose envelope was removed using the Hilbert transform, leaving only the fine structure. One interval contained the fine structure of an amplitude modulated stimulus, the other the fine structure of an unmodulated stimulus. The first experiment measured AM detection for a fixed modulation index (m=0.95). The original signal carriers were broadband noise, harmonic tone complexes, and positive Schroeder-phase complexes modulated at rates of 5, 10, or 15 Hz. Listeners were unable to detect AM when presented with the fine structure only, suggesting little envelope recovery. The second experiment measured AM detection thresholds for modulation rates of 5, 10, or 15 Hz imposed, before combination, on one of three nonharmonically related tones. Preliminary results indicate that thresholds are comparable whether listeners are presented with the full signal or fine structure only, suggesting that the depth of the recovered AM is similar to that of the original AM for these stimuli. [Work supported by NIDCD.]
Cricket bats: Some performance and vibration control issues
Authors: John Sabu , Jialong Cao , Gutaj Fatmir , Molyneaux Tom
Published: October 2013

This paper will address some of the issues in an on-going research project involving the performance optimization and vibration control of Cricket bats. In many ways, the rules of the game have made our task a little easier by restricting exactly what we can modify in order to improve performance. For example, the blade or the hitting proportion of the Cricket bat has to remain as wood but its geometry can be altered to fit within a volume-based specification. The handles specification, however, is not specified. Hence by our interpretation of the rules of the game, this lack of specificity for the handle in the rules provides an opportunity to improve the performance of the Cricket bat as a whole by making material and geometric modifications to the handle. This paper will address the investigation of bat performance from a dynamics and vibration analyses perspective. This paper will report on parameters such as bat–ball contact time and translation, clustering of distal node points (DNPs) to mimic an enhanced sweet spot. Results showing performance comparisons between traditional and composite material-handle bats will be presented along with computational and analytical results for various handle shapes.
Learning segments from waveforms: A statistical model of early phonological acquisition
Authors: Lin Ying
Published: October 2013

We consider the problem of early phonological acquisition within a statistical learning framework. Given a set of waveforms, our goal is to output a set of models for phonological categories as well as representations of the utterances in terms of these categories. The basic assumption of our model is that the learning of sound categories neither precedes nor follows segmentation of the waveform, but improves together with segmentation in an iterative manner. In statistical learning terms, segmentation is regarded as ‘‘missing data,’’ while category models are treated as parameters of interest. Our algorithm iterates over two basic steps: First, given a set of category models, we compute a mixture of segmentations for each utterance; Second, we improve the category models with unlabeled segments using unsupervised learning. Starting from an acoustic segmentation, each iteration produces an initial estimate of the parameters for the next iteration, until the algorithm converges to a set of sublexical models and a set of segmentations for each utterance. The results of running this algorithm on TIMIT and motherese data suggest that it approximately identifies segment-sized units and their associated categories in a completely unsupervised manner.
Sounds and vibrations recorded on and beneath landfast sea ice during construction of an artificial gravel island for oil production in the Alaska Beaufort Sea
Authors: Greene Charles R.
Published: October 2013

Underwater and airborne sounds and ice-borne vibrations were recorded from sea-ice near an artificial gravel island during its initial construction. Recordings were made in winter 2000 when BP began constructing Northstar Island about 5 km offshore. Underwater and airborne sounds were recorded over frequencies from 10 to 10000 Hz; particle motion in the ice was recorded from 10 to 500 Hz. Ice thickness was about 1.6 m. Water depth at the island was 12 m, and depths ranged between 4 and 13 m at recording stations. Recording distances were from about 100 m to over 5 km. Activities recorded included ice augering, pumping sea water to flood the ice and build an ice road, a dozer plowing snow, cutting ice with a Ditch Witch, trucks hauling gravel over an ice road to the island site, and a backhoe trenching the sea bottom for a pipeline. Dominant frequencies were generally below 500 Hz. The Ditch Witch cutting ice was one of the stronger sounds and was audible underwater and as ice vibration to distance 3 km. Other sounds diminished to background levels by a distance of 2 km. Airborne sound detection depended on wind speed and direction. [Work supported by BP.]
Vibration and sound radiation of solid wood and tubular metal baseball bats as a function of ball–bat location
Authors: Collier Robert D. , Kaliski Kenneth , Sherwood James A.
Published: October 2013

The ‘‘crack of the bat’’ is an important part of the game of baseball played with solid wood bats. The spectral characteristics of the radiated sound depend on the location of the ball–bat impact location along the length of the barrel and the resulting bat vibration. Balls hit on the sweet spot generally are hit harder and result in a distinct and recognizable ‘‘crack’’ sound. On the other hand, balls hit in on the handle or off the end of the barrel result in different modes of vibration and low-frequency radiation, i.e., a ‘‘thunk-like’’ sound. Analytical predictions and modal analyses, supported by both laboratory and field measurements, provide a more comprehensive picture of bat vibration and radiated sound relationships. Comparisons are made with tubular metal bats which exhibit the narrow-band signature due to excitation of the cylindrical breathing (bell) modes which are essentially independent of hit location. The differences in bat vibration and sound radiation can provide important clues for baseball players in the field.
Robert Young’s contributions to musical acoustics
Authors: Hansen Uwe J.
Published: October 2013

Of Bob’s 32 publications in musical acoustics 17 dealt with tuning and intonation. These publications span a time period of 43 years. Among them are two reviews in JASA, one in 1954: ‘‘Twenty-five Years of Musical Acoustics,’’ and one in 1979: ‘‘Fifty years of musical acoustics in the Acoustical Society of America.’’ Some of Bob’s important contributions to tuning and intonation will be discussed, one of which was the invention with Allan Loomis of the Chromatic Stroboscope while he was employed at the C.G. Conn Music Company in the 1930s. Dan Martin, in a review of the device, called the Chromatic Stroboscope the most-precise frequency-measuring instrument available for acoustical research in the audio-frequency range. Current activities in musical acoustics in view of Bob’s 25- and 50-year review comments will be considered.
A sub-mesoscale hydrodynamic/acoustic simulation model for continental shelf-break regions
Authors: Finette Steven , Shen Colin Y. , Evans Thomas E.
Published: October 2013

A nonhydrostatic, hydrodynamic model of the sound speed field in a continental shelf-break environment has been developed and implemented. The model is based on a vorticity formulation of the equations of motion for an incompressible fluid with a free ocean surface, and it is capable of simulating the generation and propagation of internal tides and solibores under tidal forcing. The model has been benchmarked with an exact numerical solution for a soliton. A set of space and time evolving sound speed distributions is integrated with a parabolic equation code to compute time and frequency dependent pressure fields. Two-dimensional examples of broad-band signal gain degradation on vertical arrays in this environment are presented, as well as range-frequency maps that illustrate the structure of the waveguide invariant in a shelf-break environment that is changing in time. Implications for source localization are considered. [Work supported by ONR.]
Sound scattering by 3-D, time-dependent internal gravity wave fields in the ocean
Authors: Godin Oleg A. , Voronovich Alexander G. , Zavorotny Valery U.
Published: October 2013

In a wide range of sound frequencies, internal gravity waves (IWs) are the major cause of underwater sound scattering and resulting fluctuations in acoustic quantities. In this paper, IW-induced variations in acoustic travel times, grazing and azimuthal arrival angles, and frequency spectra are analyzed and their implications for acoustic oceanography are emphasized. Statistical properties of IW-induced acoustic fluctuations are studied within ray and modal representations of the acoustic field. Ray perturbation theory is developed to extend results previously obtained using eikonal perturbation theory to rays which encounter an arbitrary number of caustics on their way from a source to a receiver. Effects of mode coupling on acoustic travel time variance and bias are quantified in range-dependent and horizontally-inhomogeneous environments. Time-dependent, IW-induced variations of sound speed are shown to result in a detectable wander of frequency of the received signal emitted by a CW sound source at rest. Acoustic frequency variance on refracted rays is proportional to spatial density of IW energy. Feasibility of quantifying internal wave energy density and its variation in time through measurements of spectra of acoustic signals received along resolved ray paths from a highly stable source is discussed. [Work supported by ONR.]
The effect of marine sediments on the underwater penetration of a sonic boom
Authors: Godin Oleg A. , Chapman David M. F.
Published: October 2013

Understanding and quantifying sonic boom penetration into the ocean is of substantial practical interest because of the potential impact of supersonic aircraft on marine mammals. Observations by Desharnais and Chapman [F. Desharnais and D. M. F. Chapman, J. Acoust. Soc. Am. 111, 544–553 (2002)] indicate, in qualitative agreement with numerical simulations, that sonic boom penetration in coastal regions may be significantly enhanced compared to the deep water case by the resonant excitation of seismo-acoustic waves in marine sediments. In this paper, an analytic theory originally developed to model interface waves in soft sediments with power-law shear speed profiles [O. A. Godin and D. M. F. Chapman, J. Acoust. Soc. Am. 110, 1890–1907 (2001)] is extended to simulate the shallow-water sound field induced by a shock wave incident from the air side. The theory explains salient features of the observations, including the nonmonotonic depth dependence of the sound exposure spectral density (SESD). Our analysis demonstrates that SESD in shallow water is sensitive to the geoacoustic parameters of the seabed, particularly the shear modulus profile. It may be possible to extract the shear wave attenuation coefficient in the sediment at low frequencies by analyzing sonic boom records from a vertical line array of hydrophones.
Sound preferences in urban open public spaces
Authors: Kang Jian , Yang Wei
Published: October 2013

This paper studies people’s perception of sound, based on an intensive questionnaire survey in fourteen urban open public spaces of five European countries. The questionnaire includes identification of recognized sounds, classification of sound preference, and indication of wanted and unwanted sounds. The results indicate three facets to people’s sound preferences. First, people generally prefer natural and culture-related sounds rather than artificial sounds. Vehicle sounds and construction sounds are regarded as the most unpopular, whereas sounds from human activities are normally rated as neutral. Second, cultural background and long-term environmental experience play an important role in people’s judgment of sound preference. People from a similar environment may show a similar tendency on their sound preferences, which can be defined as macro-preference. Third, personal differences, such as age and gender, further influence people’s sound preference, which can be defined as micro-preference. For example, with increasing age, a higher percentage of people are favorable to, or tolerate, sounds relating to nature, culture or human activities. Male and female exhibit only slight differences. [Work supported by the European Commission.]
Effects of an acoustic diode on the pressure waveform and cavitation bubble dynamics produced by a piezoelectric shock wave generator
Authors: Zhu Songlin , Zhong Pei
Published: October 2013

High-speed schlieren imaging, combined with fiber optical probe hydrophone (FOPH) and passive cavitation detection (PCD) were used to access the effects of an acoustic diode (AD) on the pressure waveform and associated cavitation activities produced by a piezoelectric shock wave (PSW) generator. Without the AD, a typical pressure waveform at the focus of the PSW generator consists of a leading shock wave, followed by a tensile wave and several oscillation waves (OWs) of gradually reduced amplitudes. When the AD was placed 30 mm in front of the focus, the amplitude of the tensile wave was reduced and the subsequent OWs were removed. The pulse intensity integral of the tensile wave was reduced by 58%, and subsequently, PSW-induced bubble dynamics were altered significantly. Based on PCD data, the collapse time of cavitation bubble(s) was reduced by about 11%. Although intensive collapse of microbubbles was observed in about 10 μs following the shock front of the original PSW, the forced collapse of microbubbles was not observed when the AD was used, presumably due to the removal of the OWs. Theoretical calculation based on the Gilmore model confirmed these experimental observations. [Work supported by the Whitaker Foundation and NIH.]
Acoustic near field effects for the Simrad–Mesotech SM 2000 multibeam sonar
Authors: Cochrane Norman A. , Melvin Gary D.
Published: October 2013

Targets quantitatively observed with a multibeam sonar based on a truncated circular arc transducer geometry, focused at infinity, display anomalous apparent target strengths at short measurement ranges. Three near field mechanisms, affecting both the sonar transmit and receive responses, are identified: (1) Anomalous inter-elemental differential phase shifts, (2) inter-elemental differential spreading losses, (3) shifts in elemental viewing aspect. With reference to a commercial 200 kHz Simrad–Mesotech SM 2000 multibeam sonar, the relative importances of the three mechanisms are numerically examined at a 1-m target range. Combined effects in both transmit and in receive are further evaluated for target ranges between 0.5 and 20 m. For the instrument considered, near field effects are significant at ranges of 5 m and less and are characterized by systematically reduced target amplitudes after the application of ‘‘normal’’ sonar time variable gain. Systematic broadening of combined transmit–receive response patterns at short target ranges result in target defocusing in sonar imaging applications. Experimentally measured responses are presented for comparison with theory. [Work supported by the DFO National Hydroacoustic Program and generous access to the Defence Research & Development Canada—Atlantic acoustic calibration facilities.]
Daptomycin Dosing Based on Ideal Body Weight versus Actual Body Weight: Comparison of Clinical Outcomes
Authors: Ng Jennifer K. , Schulz Lucas T , Rose Warren E. , Fox Barry C. , Andes David R. , Buhr Kevin A. , Fish Jeffrey T.
Published: October 2013

Daptomycin use at our institution changed to ideal body weight dosing based on a published analysis of pharmacokinetic-pharmacodynamic efficacy target attainment, bacterial ecology, and a desire to reduce drug toxicity. The current study compared outcomes between actual body weight and ideal body weight dosing of daptomycin before and after this intervention. In the evaluable group, 69 patients received doses based on actual body weight and 48 patients received doses based on ideal body weight. Patients were treated for documented
Enterococcus
species,
Staphylococcus aureus
, or coagulase-negative
Staphylococcus
infections, including bloodstream, intraabdominal, skin and soft tissue, urinary, and bone. There was no statistically significant difference in clinical success between the groups (88.9% for actual body weight compared to 89.1% for ideal body weight,
P
= 0.97). After we adjusted for gender, age, body mass index, concomitant 3-hydroxy-3-methylglutaryl–coenzyme A reductase inhibitors, infection type, and organism type, clinical success rates remained similar between groups (adjusted odds ratio of 0.68 in favor of actual body weight, 95% confidence interval [CI] of 0.13 to 3.55). Microbiological outcomes, length of stay, mortality, and adverse effects were also similar between groups. Further studies are warranted to confirm that ideal body weight dosing provides similar outcomes to actual body weight dosing for all patients and types of infections and organisms.
Anidulafungin versus Caspofungin in a Mouse Model of Candidiasis Caused by Anidulafungin-Susceptible Candida parapsilosis Isolates with Different Degrees of Caspofungin Susceptibility
Authors: Dimopoulou Dimitra , Hamilos Georgios , Tzardi Maria , Lewis Russell E. , Samonis George , Kontoyiannis Dimitrios P.
Published: October 2013

Candida parapsilosis
isolates occasionally display resistance
in vitro
to echinocandins and cause breakthrough infections to echinocandins. The degree of the
in vivo
cross-resistance among echinocandins and the fitness loss associated with caspofungin (CAS) resistance of
C. parapsilosis
are not well studied. We compared the activities of CAS and anidulafungin (ANF), each given at 2 dosing schedules (high dose or low dose) in a nonneutropenic mouse model of invasive candidiasis (IC) caused by ANF-susceptible isolates of
C. parapsilosis
with different degrees of susceptibility to CAS (CAS resistant [CAS-R], MIC, >16 mg/liter; CAS intermediate [CAS-I], MIC, 4 mg/liter; and CAS susceptible [CAS-S], MIC, 2 mg/liter). We analyzed tissue fungal burden, histopathology, and weight loss patterns. Increasing CAS resistance was associated with reduced virulence of
C. parapsilosis
isolates (mortality rates for CAS-S versus CAS-I versus CAS-R, 100% versus 11.1% versus 0%, respectively;
P
< 0.001). High doses of either echinocandin were active against infection with the CAS-I isolate when assessed by fungal burden reduction and weight gain. In contrast to CAS-S and CAS-I isolates, there was no reduction in fungal burden in mice infected with the CAS-R isolate following treatment with either echinocandin, each given at a high or low dose. Nevertheless, mice infected with the CAS-R isolate had reduced disease severity following echinocandin treatment, suggesting that echinocandins have activity
in vivo
, even against echinocandin-resistant strains. A complex interplay of residual echinocandin activity, decreased virulence, and/or fitness of isolates with altered cell wall and possible immunomodulatory effects can be encountered
in vivo
during infection with CAS-resistant
C. parapsilosis
isolates.
Retrospective Molecular Analysis of DIM-1 Metallo-β-Lactamase Discovered in Pseudomonas stutzeri from India in 2000
Authors: Deshpande Lalitagauri M. , Jones Ronald N. , Woosley Leah N. , Castanheira Mariana
Published: October 2013

Among 220 clinical isolates of Gram-negative bacilli collected in India during 2000, 22 strains showing elevated imipenem MICs were evaluated for carbapenemase production. One DIM-1-producing
Pseudomonas stutzeri
isolate was detected, and no other carbapenemase-encoding genes were identified. This detection of a DIM-1-producing
P. stutzeri
isolate from India predating the finding of this gene in the index Dutch strain and the very recent detection of DIM-1 in Africa suggest an unidentified environmental source of this metallo-β-lactamase gene.
Human Cytomegalovirus UL97 Kinase Is Involved in the Mechanism of Action of Methylenecyclopropane Analogs with 6-Ether and -Thioether Substitutions
Authors: Komazin-Meredith Gloria , Chou Sunwen , Prichard Mark N. , Hartline Caroll B. , Cardinale Steven C. , Comeau Katelyn , Williams John D. , Khan Atiyya R. , Peet Norton P. , Bowlin Terry L.
Published: October 2013

Methylenecyclopropane nucleoside (MCPN) analogs are being investigated for treatment of human cytomegalovirus (HCMV) infection because of favorable preclinical data and limited ganciclovir cross-resistance. Monohydroxymethyl MCPNs bearing ether and thioether functionalities at the purine 6 position have antiviral activity against herpes simplex virus (HSV) and varicella-zoster virus (VZV) in addition to HCMV. The role of the HCMV UL97 kinase in the mechanism of action of these derivatives was examined. When tested against a kinase-inactive UL97 K355M virus, a moderate 5- to 7-fold increase in 50% effective concentration (EC
50
) was observed, in comparison to a 13- to 25-fold increase for either cyclopropavir or ganciclovir. Serial propagation of HCMV under two of these compounds selected for three novel UL97 mutations encoding amino acid substitutions D456N, C480R,and Y617del. When transferred to baseline laboratory HCMV strains, these mutations individually conferred resistance to all of the tested MCPNs, ganciclovir, and maribavir. However, the engineered strains also demonstrated severe growth defects and abnormal cytopathic effects similar to the kinase-inactive mutant. Expressed and purified UL97 kinase showed
in vitro
phosphorylation of the newly tested MCPNs. Thus, HCMV UL97 kinase is involved in the antiviral action of these MCPNs, but the
in vitro
selection of UL97-defective viruses suggests that their activity against more typical ganciclovir-resistant growth-competent UL97 mutants may be relatively preserved.
Burkholderia pseudomallei Isolates from Sarawak, Malaysian Borneo, Are Predominantly Susceptible to Aminoglycosides and Macrolides
Authors: Podin Yuwana , Sarovich Derek S. , Price Erin P. , Kaestli Mirjam , Mayo Mark , Hii KingChing , Ngian HieUng , Wong SeeChang , Wong IngTien , Wong JinShyan , Mohan Anand , Ooi MongHow , Fam TemLom , Wong Jack , Tuanyok Apichai , Keim Paul , Giffard Philip M. , Currie Bart J.
Published: October 2013

Melioidosis is a potentially fatal disease caused by the saprophytic bacterium
Burkholderia pseudomallei
. Resistance to gentamicin is generally a hallmark of
B. pseudomallei
, and gentamicin is a selective agent in media used for diagnosis of melioidosis. In this study, we determined the prevalence and mechanism of gentamicin susceptibility found in
B. pseudomallei
isolates from Sarawak, Malaysian Borneo. We performed multilocus sequence typing and antibiotic susceptibility testing on 44
B. pseudomallei
clinical isolates from melioidosis patients in Sarawak district hospitals. Whole-genome sequencing was used to identify the mechanism of gentamicin susceptibility. A novel allelic-specific PCR was designed to differentiate gentamicin-sensitive isolates from wild-type
B. pseudomallei
. A reversion assay was performed to confirm the involvement of this mechanism in gentamicin susceptibility. A substantial proportion (86%) of
B. pseudomallei
clinical isolates in Sarawak, Malaysian Borneo, were found to be susceptible to the aminoglycoside gentamicin, a rare occurrence in other regions where
B. pseudomallei
is endemic. Gentamicin sensitivity was restricted to genetically related strains belonging to sequence type 881 or its single-locus variant, sequence type 997. Whole-genome sequencing identified a novel nonsynonymous mutation within
amrB
, encoding an essential component of the AmrAB-OprA multidrug efflux pump. We confirmed the role of this mutation in conferring aminoglycoside and macrolide sensitivity by reversion of this mutation to the wild-type sequence. Our study demonstrates that alternative
B. pseudomallei
selective media without gentamicin are needed for accurate melioidosis laboratory diagnosis in Sarawak. This finding may also have implications for environmental sampling of other locations to test for
B. pseudomallei
endemicity.
Activities of Fosfomycin and Rifampin on Planktonic and Adherent Enterococcus faecalis Strains in an Experimental Foreign-Body Infection Model
Authors: Oliva Alessandra , Furustrand Tafin Ulrika , Maiolo Elena Maryka , Jeddari Safaa , Bétrisey Bertrand , Trampuz Andrej
Published: October 2013

Enterococcal implant-associated infections are difficult to treat because antibiotics generally lack activity against enterococcal biofilms. We investigated fosfomycin, rifampin, and their combinations against planktonic and adherent
Enterococcus faecalis
(ATCC 19433)
in vitro
and in a foreign-body infection model. The MIC/MBC
log
values were 32/>512 μg/ml for fosfomycin, 4/>64 μg/ml for rifampin, 1/2 μg/ml for ampicillin, 2/>256 μg/ml for linezolid, 16/32 μg/ml for gentamicin, 1/>64 μg/ml for vancomycin, and 1/5 μg/ml for daptomycin. In time-kill studies, fosfomycin was bactericidal at 8× and 16× MIC, but regrowth of resistant strains occurred after 24 h. With the exception of gentamicin, no complete inhibition of growth-related heat production was observed with other antimicrobials on early (3 h) or mature (24 h) biofilms. In the animal model, fosfomycin alone or in combination with daptomycin reduced planktonic counts by ≈4 log
10
CFU/ml below the levels before treatment. Fosfomycin cleared planktonic bacteria from 74% of cage fluids (i.e., no growth in aspirated fluid) and eradicated biofilm bacteria from 43% of cages (i.e., no growth from removed cages). In combination with gentamicin, fosfomycin cleared 77% and cured 58% of cages; in combination with vancomycin, fosfomycin cleared 33% and cured 18% of cages; in combination with daptomycin, fosfomycin cleared 75% and cured 17% of cages. Rifampin showed no activity on planktonic or adherent
E. faecalis
, whereas in combination with daptomycin it cured 17% and with fosfomycin it cured 25% of cages. Emergence of fosfomycin resistance was not observed
in vivo
. In conclusion, fosfomycin showed activity against planktonic and adherent
E. faecalis
. Its role against enterococcal biofilms should be further investigated, especially in combination with rifampin and/or daptomycin treatment.
PRICING AND INVENTORY DECISIONS WITH UNCERTAIN SUPPLY AND STOCHASTIC DEMAND
Authors: SURTI CHIRAG , HASSINI ELKAFI , ABAD PRAKASH
Published: October 2013

We consider a retailer, facing uncertain supply and price-sensitive stochastic demand, who has to make stocking and pricing decisions for a given selling period. We also consider the case when the demand is price-sensitive deterministic and provide a unified framework for the model with additive errors. For both scenarios, we look at the case when the price is set before receiving the supply, called simultaneous pricing and the case when the price is set after receiving it, which is called postponed pricing. We develop a procedure for finding the optimal policy for the retailer with general distributions for the supply and the demand. To study the effect of supply uncertainty on expected profit, we conduct sensitivity analysis and develop results for both pricing scenarios and give insights. The results have important implications for a retailer in the supply chain, where a portion of the inventory may be lost due to variety of factors including mishandling and failure to meet quality standards. The findings shed light on the nature and role of prices and their relationship to supply and demand.
UNIVERSALLY RATIONAL BELIEF HIERARCHIES
Authors: TSAKAS ELIAS
Published: October 2013

In a recent paper, Tsakas [2013 Rational belief hierarchies, Journal of Mathematical Economics, Maastricht University] introduced the notion of rational beliefs. These are Borel probability measures that assign a rational probability to every Borel event. Then, he constructed the corresponding Harsanyi type space model that represents the rational belief hierarchies. As he showed, there are rational types that are associated with a non-rational probability measure over the product of the underlying space of uncertainty and the opponent's types. In this paper, we define the universally rational belief hierarchies, as those that do not exhibit this property. Then, we characterize them in terms of a natural restriction imposed directly on the belief hierarchies.
STUDIES ON NEPHRITE AND JADEITE JADES BY FOURIER TRANSFORM INFRARED (FTIR) AND RAMAN SPECTROSCOPIC TECHNIQUES
Authors: TAN T. L. , NG L. L. , LIM L. C.
Published: October 2013

The mineralogical properties of black nephrite jade from Western Australia are studied by Fourier transform infrared (FTIR) spectroscopy using both transmission and specular reflectance techniques in the 4000–400 cm-1 wavenumber region. The infrared absorption peaks in the 3700–3600 cm-1 region which are due to the O – H stretching mode provides a quantitative analysis of the Fe /( Fe + Mg ) ratio in the mineral composition of jade samples. The Fe /( Fe + Mg ) percentage in black nephrite is found to be higher than that in green nephrite, but comparable to that of actinolite (iron-rich nephrite). This implies that the mineralogy of black nephrite is closer to actinolite than tremolite. The jade is also characterized using Raman spectroscopy in the 1200–200 cm-1 region. Results from FTIR and Raman spectroscopic data of black nephrite jade are compared with those of green nephrite jade from New Zealand and jadeite jade from Myanmar. Black nephrite appears to have a slightly different chemical composition from green nephrite. Spectra from FTIR and Raman spectroscopic techniques were found to be useful in differentiating black nephrite, green nephrite, and green jadeite jades. Furthermore, data on refractive index, specific gravity, and hardness of black nephrite jade are measured and compared with those of green nephrite and of jadeite jade.
ON IMPLEMENTATION AND PERFORMANCE OF AN ANISOTROPIC CONSTITUTIVE MODEL FOR CLAYS
Authors: MANZARI MAJID T. , YONTEN KARMA
Published: October 2013

Numerical implementation of an anisotropic constitutive model for clays (SANICLAY) is presented. Moreover, a case study in which a soil embankment is placed on a K0-consolidated over-consolidated clay is analyzed by conducting an elastoplastic fully-coupled finite element analysis. It is shown that anisotropy has significant impact on the ground settlement caused by the placement of soil embankment and on the pore pressure generation and dissipation within the foundation soil. The simulations using SANICLAY favorably compare with the field measurements of ground settlement and pore pressure. The drawbacks of the use of an isotropic elastoplastic model (Cam Clay) are also demonstrated.
Chinese-Japanese Machine Translation Exploiting Chinese Characters
Authors: Chu Chenhui , Nakazawa Toshiaki , Kawahara Daisuke , Kurohashi Sadao
Published: October 2013

The Chinese and Japanese languages share Chinese characters. Since the Chinese characters in Japanese originated from ancient China, many common Chinese characters exist between these two languages. Since Chinese characters contain significant semantic information and common Chinese characters share the same meaning in the two languages, they can be quite useful in Chinese-Japanese machine translation (MT). We therefore propose a method for creating a Chinese character mapping table for Japanese, traditional Chinese, and simplified Chinese, with the aim of constructing a complete resource of common Chinese characters. Furthermore, we point out two main problems in Chinese word segmentation for Chinese-Japanese MT, namely, unknown words and word segmentation granularity, and propose an approach exploiting common Chinese characters to solve these problems. We also propose a statistical method for detecting other semantically equivalent Chinese characters other than the common ones and a method for exploiting shared Chinese characters in phrase alignment. Results of the experiments carried out on a state-of-the-art phrase-based statistical MT system and an example-based MT system show that our proposed approaches can improve MT performance significantly, thereby verifying the effectiveness of shared Chinese characters for Chinese-Japanese MT.
Web table taxonomy and formalization
Authors: Lautert Larissa R. , Scheidt Marcelo M. , Dorneles Carina F.
Published: October 2013

The Web is the largest repository of data available, with over 150 million high-quality tables. Several works have combined efforts to allow queries on these tables, but there are still challenges, like the various different types of structures found on the Web. In this paper, we propose a taxonomy for the tabular structures and formalize the ones used with relational data and show, through an experimental evaluation, that WTClassifier, our supervised framework, classifies Web tables with high accuracy. Additionally, we use WTClassifier to categorize more than 300 thousandWeb tables into our taxonomy and found that 82.25% are not formatted similarly to relational structure.
Polymeric Nanosuspensions for Enhanced Dissolution of Water Insoluble Drugs
Authors: Yadollahi Roya , Vasilev Krasimir , Prestidge Clive A. , Simovic Spomenka
Published: October 2013

The aim of the present research is to formulate and evaluate polymeric nanosuspensions containing three model water insoluble drugs, nifedipine (NIF), carbamazepine (CBZ), and ibuprofen (IBU) with various physicochemical properties. The nanosuspensions were prepared from hydroxypropyl methylcellulose (HPMC) and polyvinylpyrrolidone (PVP) by a cosolvent technique with polyethylene glycol (PEG‐300) and water as the cosolvents. Physicochemical and morphological characteristics of the nanosuspensions (particle size, polydispersity index, and crystallinity) have been correlated with the drug release behaviour. The effects of polymer, drug ratio on the physical, morphological, and dissolution characteristics of the drugs are reported. Drug release is significantly enhanced from the nanosuspensions; for example, the maximum NIF, IBU, and CBZ concentrations after 8‐hour dissolution are increased approximately 37, 2, and 1.2 times, respectively, in comparison with the pure powdered drugs. Based on this solubilization enhancement performance, the nanosuspensions have potential for increasing the orally dosed bioavailability of NIF, IBU, and CBZ.