bluuebunny/crossref_metadata_2025 huggingface dataset:
Kinetics of Photosynthetic Response to Ultraviolet and Photosynthetically Active Radiation in Synechococcus WH8102 (CYANOBACTERIA)
Authors: Fragoso Glaucia M. , Neale Patrick J. , Kana Todd M. , Pritchard Alicia L.
Published: November 2013

The picoplanktonic cyanobacteria, Synechococcus spp., (Nägeli) are important contributors to global ocean primary production that can be stressed by solar radiation, both in the photosynthetically active (PAR) and ultraviolet (UV) range. We studied the responses of PSII quantum yield (active fluorescence), carbon fixation (14C assimilation) and oxygen evolution (membrane inlet mass spectrometry) in Synechococcus WH8102 under moderate UV and PAR. PSII quantum yield decreased during exposure to moderate UV and UV+PAR, with response to the latter being faster (6.4 versus 2.8 min, respectively). Repair processes were also faster when UV+PAR exposure was followed by moderate PAR (1.68 min response time) than when UV was followed by very low PAR (10.5 min response time). For the UV+PAR treatment, the initial decrease in quantum yield was followed by a 50% increase (“rebound”) after 7 min exposure, showing an apparent photoprotection induction. While oxygen uptake increased with PAR, it did not change under UV, suggesting that this oxygen‐dependent mechanism of photoprotection, which may be acting as an electron sink, is not an important strategy against UV. We used propyl gallate, an antioxidant, to test for plastid terminal oxidase (ptox) or ptox‐like enzymes activity, but it caused nonspecific and toxic effects on Synechococcus WH8102.
Multiphase partial and selective dolomitization of Carnian reef limestone (Transdanubian Range, Hungary)
Authors: Haas János , Budai Tamás , Győri Orsolya , Kele Sándor
Published: November 2013

Partially dolomitized carbonate successions provide a good opportunity to understand the commonly multistage process of dolomitization. Petrographic methods, fluid inclusion microthermometry and stable isotope measurements were applied to reconstruct the diagenetic evolution and dolomitization of a partially dolomitized Carnian reef limestone from the Transdanubian Range, Hungary. The diagenetic history began with reef diagenesis and formation of dolomite micro‐aggregates in microbial fabric elements; this was followed by the development of euhedral porphyrotopic dolomite crystals through overgrowths around the previously formed dolomite micro‐aggregates during the earliest burial stage. Increasing burial resulted in the extension of the dolomite patches via formation of finely crystalline replacement dolomite. From the Late Norian, when the Carnian reef carbonates reached the depth of 1·0 to 1·8 km, the diagenetic evolution continued in an intermediate to deep‐burial setting. Contemporaneously, an extensional regime was established, leading to fracturing. The progressive burial resulted in the recrystallization of the pre‐existing dolomite with increasing temperature, while saddle dolomite cement was precipitated in fractures. In connection with the Alpine Orogeny, intense denudation took place during the Late Cretaceous, accompanied by fracturing. Similar tectonically controlled denudation and fracturing occurred in several stages during the Cenozoic. As a result of these processes, the studied Carnian carbonates were raised to a near‐surface position or became subaerially exposed, leading to dedolomitization of the last dolomite phase and precipitation of calcite cement in cavities and fractures. This study revealed that by investigating partially and selectively dolomitized rock types, it is possible to document and understand those stages of the multiple dolomitization process which can barely be detected in the completely dolomitized rock bodies. Recognition of the dolomitization phases could provide the basis for the analysis of their relations with the depositional, diagenetic and tectonic processes, and stages of basin evolution.
Development of an incised valley‐fill at an evolving rift margin: Pleistocene eustasy and tectonics on the southern side of the Gulf of Corinth, Greece
Authors: Gobo Katarina , Ghinassi Massimiliano , Nemec Wojciech , Sjursen Eivind
Published: November 2013

This study from the southern margin of the Gulf of Corinth documents a Late Pleistocene incised valley‐fill succession that differs from the existing facies models, because it comprises gravelly shoal‐water and Gilbert‐type deltaic deposits, shows strong wave influence and lacks evidence of tidal activity. The valley‐fill is at least 140 m thick, formed in 50 to 100 ka between the interglacials Marine Isotope Stage 9a and Marine Isotope Stage 7c. The relative sea‐level rise left its record both inside and outside the incised valley, and the age of the valley‐fill is estimated from a U/Th date of coral‐bearing deposits directly outside the palaeovalley outlet. Tectonic up‐warping due to formation of a valley‐parallel structural relay ramp contributed to the valley segmentation and limited the landward extent of marine invasions. The valley segment upstream of the ramp crest was filled with a gravelly alluvium, whereas the downstream segment accumulated fluvio‐deltaic deposits. The consecutive deltaic systems nucleated in the ramp‐crest zone, forming a bathymetric gradient that promoted the ultimate growth of thick Gilbert‐type delta. The case study contributes to the spectrum of conceptual models for incised valley‐fill architecture. Four key models are discussed with reference to the rates of sediment supply and accommodation development, and it is pointed out that not only similarity, but also all departures of particular field cases from these end‐member models may provide valuable information on the system formative conditions. The Akrata incised valley‐fill represents conditions of high sediment supply and a rapid, but stepwise development of accommodation that resulted from the spatiotemporal evolution of normal faulting at the rift margin and overprinted glacioeustatic signals. This study adds to an understanding of valley‐fill architecture and provides new insights into the Pleistocene tectonics and palaeogeography of the Corinth Rift margin.
Transfusion of packed red blood cells reduces selenium levels and increases lipid peroxidation in an in vivo ovine model
Authors: McDonald C. I. , Fraser J. F. , Shekar K. , Dunster K. R. , Thom O. , Fung Y. L.
Published: November 2013

Background

Oxidative stress from surgery or critically illness has been shown to adversely contribute to morbidity and mortality. Recent studies record that oxidative stress is heightened following packed red blood cell (PRBC) transfusions and that products of oxidative stress accumulate as the PRBC ages. However, there are no studies that investigate if transfusion of aged PRBC actually increases the recipient's oxidative stress profile more than fresh PRBC.

Objective

To compare the effect of fresh vs aged PRBC transfusions on the recipient's oxidative stress using an ovine model.

Materials and methods

Male sheep were transfused with either fresh (n = 6) or aged (n = 6) ovine PRBC, and serial blood samples taken. Plasma samples were analysed for lipid peroxidation using the thiobarbituric acid reactive substances (TBARS) assay. This served as an indicator of oxidative injury. Antioxidant function and trace element levels were also measured.

Results

Like human PRBC, the ovine PRBC had negligible selenium levels. Irrespective of age, PRBC transfusion was associated with reduced selenium levels and antioxidant function, which correlated with increased markers of lipid peroxidation.

Conclusion

Transfusion of selenium poor PRBC can dilute selenium levels and compromise glutathione peroxidase antioxidant activity and thereby allow lipid peroxidation. As there was no evidence that aged PRBC induced more severe oxidative injury this suggests that selenium dilution is a key underlying mechanism. Further studies are needed to assess the impact of transfusion‐related oxidative stress in massive transfusions.
Monitoring Cellular Trafficking of Nanoparticle Cargo in Murine Macrophages Through Plasmon Coupling Microscopy
Authors: Reinhard Björn M. , Wang Hongyun , Wu Linxi
Published: November 2013

A detailed analysis of silver nanoparticle (NP) uptake and trafficking in the murine macrophage cell line J774A.1 through spectral analysis of the resonance wavelength of the metal NP cargo is presented. The NP spectra reveal a strong phenotypic variability in the NP uptake and processing on the single cell level. Cells containing non- or low-agglomerated NPs are found to coexist with cells containing NPs of varying degrees of NP agglomeration, clearly indicated by a spectral red-shift in the resonance wavelength. Pharmacological inhibition studies indicate that the observed differences in the intracellular NP organization result from coexisting actin- and clathrin-dependent endocytosis mechanisms. Correlation with fluorescence macrophage maturity markers shows that differentiated J774A.1 macrophages preferentially contain compact NP agglomerates, whereas monocyte-like macrophages contain non-agglomerated NPs.
Study the Effects of Padding Materials on the Level of the Load in the Brain
Authors: Salimi Jazi Mehdi , Rezaei Asghar , Karami Ghodrat , Azarmi Fardad , Ziejewski Mariusz
Published: November 2013

Experiencing a speedy strain or acceleration causes Traumatic Brain Injury (TBI) that can be classified into mild, moderate and severe, based on the level of the injury. Motor vehicles crashes; violence related injuries; collisions in sports; and falls are most common causes of TBI. Moreover in the military service TBI can be happened when soldiers are exposed to shock waves due to blasts or because of ballistic impact.
Blebbing Dynamics, Single Cell Force Measurements, and the Influence of Cytochalasin D on Glioblastoma Multiforme Cells Using STEP Fibers
Authors: Sharma Puja , Koons Brian , Nain Amrinder S.
Published: November 2013

Classified as a grade IV tumor of the central nervous system, Glioblastoma multiforme (GBM) arises from the glia. A poor understanding of tumor metastasis and limited treatment options have led to increase in deaths of patients suffering from GBM. Studying glioma behavior using aligned structures that mimic native glioblastoma metastatic path is challenging. In this study, we utilize a previously described non-electrospinning platform to manufacture aligned 3D structures called STEP nanonets that not only allows the study of individual cell-nanofiber interaction, but also allows the calculation of migratory forces using beam mechanics. In particular, the blebbing dynamics, force generation, and the effect of an actin disruptor, Cytochalasin D have been investigated on a glioma cell line (DBTRG, Denver Based Tumor Research Group). It was observed that cell pulled onto the nanofibers causing measurable deflections when they were in spread and non-blebbing conditions. In non-spread configurations while attached to fibers, the cells acquired spherical configurations and resumed blebbing. The average migratory force generated by cells exposed to DMSO (control, 1:1000 dilution) using nanonets of 2μm by 400nm fibers was 0.58±0.06nN. Actin disruptor, Cytochalasin D severely compromised the ability of the glioma cells to migrate causing no deflection of the fibers. Forces exerted by tumor cells on their native microenvironment affects their ability to metastasize, invade and proliferate. While the result presents actin disruptor as a potential target to minimize metastasis, the influence of other cytoskeleton disruptors can also be studied using the platform. Moreover, the results obtained from the study can be utilized to better understand the individual cell – nanofibers interaction which can shed light on how cells interact with their native environment during metastasis.
Study on Specific Binding Interaction Between Protein and DNA Aptamer via Dynamic Force Spectroscopy
Authors: Ma Xiao , Shrotriya Pranav
Published: November 2013

Recently the need to design nanoscale, sensitive and flexible bio-sensors or biotic-abiotic interface keeps increasing. One of the essential challenges on this objective is to grasp a thorough understanding of the mechanism governing binding interaction between bio-molecules. In this study we aim to demonstrate the binding specificity and reveal force interaction between the anti-coagulation protein thrombin and the single-stranded DNA thrombin aptamer by application of Atomic Force Microscopy (AFM). The thiolated aptamer was deposited onto gold substrate, and then repeatedly brought into contact with a thrombin-coated AFM tip, and force drop-offs during the pull-off were measured to determine the unbinding force between the thrombin-aptamer pair. The results from experiment show that the thrombin-aptamer pair has specific binding and the force between the pair exhibits loading rate dependence. It was shown that the binding forces of the thrombin-aptamer interaction increases with growth of loading rates. The average binding force for a single thrombin/aptamer pair increased from 20 pN to 40 pN, with loading rate changes from 500pN/s to 13500pN/s. Distribution of the unbinding forces measured for each loading rate can be explained on the basis of single energy barrier model for molecular bond breakage.
Integrating Sensors With Nanostructures for Biomedical Applications
Authors: Komirisetty Archana , Williams Frances , Pradhan Aswini , Arslan Meric
Published: November 2013

This paper presents the fabrication of sensors that are integrated with nanostructures and bio-functionalized to create novel devices for biomedical applications. Biosensors are in great demand for various applications including for the agriculture and food industries, environmental monitoring, and medical diagnostics. Much research is being focused on the use of nanostructures (nanowires, nanotubes, nanoparticles, etc.) to provide for miniaturization and improved performance of these devices. The use of nanostructures is favorable for such applications since their sizes are closer to that of biological and chemical species and therefore, improve the signal generated. Moreover, their high surface-to-volume ratio results in devices with very high sensitivity. The use of nanotechnology leads to smaller, lower-power smart devices. Thus, this paper presents the integration of sensors with nanostructures for biomedical applications, specifically, glucose sensing. In the work presented, a glucose biosensor and its fabrication process flow are described. The device is based on electrochemical sensing using a working electrode with bio-functionalized zinc oxide (ZnO) nano-rods. Among all metal oxide nanostructures, ZnO nano-materials play a significant role as a sensing element in biosensors due to their properties such as high isoelectric point (IEP), fast electron transfer, non-toxicity, biocompatibility, and chemical stability which are very crucial parameters to achieve high sensitivity. Amperometric enzyme electrodes based on glucose oxidase (GOx) are used due to their stability and high selectivity to glucose. The device also consists of silicon dioxide and titanium layers as well as platinum working and counter electrodes and a silver/silver chloride reference electrode. The chlorination process on the reference electrode was optimized for various times using field emission scanning electron microscope (FESEM) and energy-dispersive X-ray spectroscopy (EDS or EDX) measurements. The ZnO nanorods were grown using the hydrothermal method and will be bio-functionalized with GOx for electrochemical sensing. Once completed, the sensors will be tested to characterize their performance, including their sensitivity and stability.
Remote Control of Cell Behaviour Through an External Magnetic Field as Tool for Nanomedicine Applications
Authors: Panseri Silvia , Sandri Monica , Cunha Carla , Iafisco Michele , Marcacci Maurilio , Tampieri Anna
Published: November 2013

The development of a new way for in vitro three-dimensional (3D) cell culture is critical for medicine to well understand cell/tissue behavior. Despite its importance, it is not easy to achieve 3D cell culture because the superficial seeding of cells on the surface of scaffolds causes tissue necrosis in the central part of scaffolds. To solve this issue, we explored an alternative cell seeding procedures based on magnetized cell guiding. Taking advantage of the novel superparamagnetic nanoparticles (MNPs), obtained by doping hydroxyapatite (HA) with Fe ions in ideal condition aimed at limiting the formation of poorly tolerated magnetic secondary phase (i.e. Fe3 O4), we magnetized cells without affect cell behavior. Moreover applying a low external magnetic field, we were able to remote control cell migration demonstrating that magnetic cells were obtained and move them in a 3D construct. This study showed the great potential of cell remote control by external magnetic field as tool for medicine applications.
Interaction With Nanoscale Topography: The Use of Nanowell-Trapped Charged Ligand-Bearing Nanoparticle Surfaces To Modulate Physiological Focal Adhesions in Endothelial Cells
Authors: Tran Phat L. , Gamboa Jessica R. , McCracken Katherine E. , Yoon Jeong-Yeol , Slepian Marvin J.
Published: November 2013

Achieving cell adhesion, growth and homeostasis on an underlying biomaterial surface may be a desirable feature in implant device design and tissue engineering. Insight has been gained from numerous cell patterning strategies where spatial cues and physical constraints have been shown to regulate the structure and function of cells. Despite significant advances in modifying substrates for cellular attachment, migration and proliferation, the achievement of confluent and aligned growth of functional endothelial cells on cardiovascular blood-contacting implants under physiologically significant wall shear stress has proven difficult. Recently we have reported on a method that enhances cellular adhesion under flow conditions on synthetic polymer surfaces, without reliance on pro-adhesive protein biomaterials, which are often thrombogenic. In this method we utilize electron beam lithography and size-dependent self-assembly to fabricate line arrays of nanowells allowing entrapment and retention of charged nanoparticles, covalently conjugated with a RGD adhesive ligand, GRGDSPK. This approach is an additive strategy of combining substrata topographic alteration, electrostatic charge and biochemical ligands, all uniquely incorporated as an ensemble of charged, ligand-bearing nanoparticles entrapped in arrays of nanowells. However, the modulation of endothelial cell physiologic mechanisms as a result of ensemble surface exposure remains to be characterized.

In this report, we extend our studies and probe cell physiologic mechanisms altered as a result of nanofeatured surface exposure. We first examined the functional intactness or normalcy of endothelial cells adherent to the nanofeatured ensemble surface utilizing standard immunostaining and flow cytometry methods. We found β1-integrin expression dominated quiescent adherent endothelial cells while αVβ3-integrins expression was more common in migratory cells. Endothelial cells were noted to express high levels of PECAM-1 over time when exposed to nanofeatured surface and RGD peptides. For understanding the contribution of the nanofeatured surface (entrapped RGD conjugated nanoparticles) to cell adhesion, cytochalasin B was used to alter cell spreading. Confocal microscopy illustrated the uptake of nanoparticles in endothelial cells on composite surfaces, as well as the inhibition of this endocytosis by cytochalasin B. After prohibiting the cells from engulfing nanoparticles, we found an 80% reduction in cell adhesion; suggesting that an endocytic mechanism might play a role in maintaining cell adhesion. Nanofeatured ensemble surfaces appear to be good substrates for achieving a high level of EC adhesion, with maintained growth and stability.
The “round trip” theory for reconstruction of Green's functions at passive locations
Authors: Moorhouse Andy , Elliott Andy
Published: November 2013

An expression for the Green's function at an arbitrary set of passive locations (no applied force) is derived and validated by experiment. Three sets of points are involved, the passive reconstruction points, c, which lie on a virtual boundary and two sets of auxiliary points, denoted a and b, located either side. The reconstruction is achieved using Green's functions forming a “round trip” from and to the reconstruction points via a and b. A two stage measurement procedure is described involving excitation at b and a but with no excitation required at the reconstruction points. A known “round trip” relationship is first introduced which is theoretically exact for points on a multi-point interface between two linear, time invariant subsystems. Experimental results for frequency response functions of a beam-plate structure show that this relationship gives good results in practice. It is then shown that the theory provides an Nth order approximation for the Green's function at arbitrary points, where N is the number of points at b. The expression is validated by reconstructing point and transfer frequency response functions at two passive points on an aluminum plate.
Decadal trends in Indian Ocean ambient sound
Authors: Miksis-Olds Jennifer L. , Bradley David L. , Maggie Niu Xiaoyue
Published: November 2013

The increase of ocean noise documented in the North Pacific has sparked concern on whether the observed increases are a global or regional phenomenon. This work provides evidence of low frequency sound increases in the Indian Ocean. A decade (2002–2012) of recordings made off the island of Diego Garcia, UK in the Indian Ocean was parsed into time series according to frequency band and sound level. Quarterly sound level comparisons between the first and last years were also performed. The combination of time series and temporal comparison analyses over multiple measurement parameters produced results beyond those obtainable from a single parameter analysis. The ocean sound floor has increased over the past decade in the Indian Ocean. Increases were most prominent in recordings made south of Diego Garcia in the 85–105 Hz band. The highest sound level trends differed between the two sides of the island; the highest sound levels decreased in the north and increased in the south. Rate, direction, and magnitude of changes among the multiple parameters supported interpretation of source functions driving the trends. The observed sound floor increases are consistent with concurrent increases in shipping, wind speed, wave height, and blue whale abundance in the Indian Ocean.
Comparing passive source localization and tracking approaches with a towed horizontal receiver array in an ocean waveguide
Authors: Gong Zheng , Tran Duong D. , Ratilal Purnima
Published: November 2013

Approaches for instantaneous passive source localization using a towed horizontal receiver array in a random range-dependent ocean waveguide are examined. They include: (1) Moving array triangulation, (2) array invariant, (3) bearings-only target motion analysis in modified polar coordinates via the extended Kalman filter, and (4) bearings-migration minimum mean-square error. These methods are applied to localize and track a vertical source array deployed in the far-field of a towed horizontal receiver array during the Gulf of Maine 2006 Experiment. The source transmitted intermittent broadband pulses in the 300 to 1200 Hz frequency range. A nonlinear matched-filter kernel designed to replicate the acoustic signal measured by the receiver array is applied to enhance the signal-to-noise ratio. The source localization accuracy is found to be highly dependent on source-receiver geometry and the localization approach. For a relatively stationary source drifting at speeds much slower than the receiver array tow-speed, the mean source position can be estimated by moving array triangulation with less than 3% error near broadside direction. For a moving source, the Kalman filter method gives the best performance with 5.5% error. The array invariant is the best approach for localizing sources within the endfire beam of the receiver array with 7% error.
Simultaneous suppression of noise and reverberation in cochlear implants using a ratio masking strategy
Authors: Hazrati Oldooz , Omid Sadjadi Seyed , Loizou Philipos C. , Hansen John H. L.
Published: November 2013

Cochlear implant (CI) recipients' ability to identify words is reduced in noisy or reverberant environments. The speech identification task for CI users becomes even more challenging in conditions where both reverberation and noise co-exist as they mask the spectro-temporal cues of speech in a rather complementary fashion. Ideal channel selection (ICS) was found to result in significantly more intelligible speech when applied to the noisy, reverberant, as well as noisy reverberant speech. In this study, a blind single-channel ratio masking strategy is presented to simultaneously suppress the negative effects of reverberation and noise on speech identification performance for CI users. In this strategy, noise power spectrum is estimated from the non-speech segments of the utterance while reverberation spectral variance is computed as a delayed and scaled version of the reverberant speech spectrum. Based on the estimated noise and reverberation power spectra, a weight between 0 and 1 is assigned to each time-frequency unit to form the final mask. Listening experiments conducted with CI users in two reverberant conditions (T60 = 0.6 and 0.8 s) at a signal-to-noise ratio of 15 dB indicate substantial improvements in speech intelligibility in both reverberant-alone and noisy reverberant conditions considered.
On the lateral resolution of focused ultrasonic fields from spherically curved transducers
Authors: Beissner K.
Published: November 2013

Focused ultrasonic fields produced by spherically curved transducers occur in many areas, as, for example, in medical ultrasonics. Recently, transducers with a central hole have increasingly appeared in practice. The present paper theoretically investigates the lateral field distribution in the geometric focal plane, based on an approach with the Rayleigh integral. Results for the lateral width of the focal maximum in that plane are presented. It turns out that the appearance of a central hole leads to a reduction in the lateral width of the focal maximum, contrary to the behavior of the longitudinal width of that maximum shown earlier.
Acoustical interaction between vibrating lips, downstream air column, and upstream airways in trombone performance
Authors: Fréour Vincent , Scavone Gary P.
Published: November 2013

This paper presents experimental results on the acoustical influence of the vocal tract in trombone performance. The experimental approach makes use of measurements at the interface between the player and instrument, allowing a relative comparison between upstream airways and the downstream air column impedances, as well as an estimation of the phase of the impedance of the upstream and downstream systems. Measurements were conducted over the full traditional range of playing, during sustained tones with varying dynamic, as well as in special effects such as pitch bending. Subjects able to play over the full range demonstrated significant upstream influence in the higher register of the instrument. These players were categorized in two groups according to their ability to control the phase of the upstream impedance and their ability to generate powerful downstream acoustic energy. Sustained tones played with varying dynamics showed a general tendency of a decrease in vocal-tract support with increase in loudness. Although pitch bends did not involve significant upstream influence at f0, results suggest modification of the lip behavior during bending. Vocal-tract tuning at tone transitions was also investigated and found to potentially contribute to slur articulations.
Temporal coherence of the acoustic field forward propagated through a continental shelf with random internal waves
Authors: Gong Zheng , Chen Tianrun , Ratilal Purnima , Makris Nicholas C.
Published: November 2013

An analytical model derived from normal mode theory for the accumulated effects of range-dependent multiple forward scattering is applied to estimate the temporal coherence of the acoustic field forward propagated through a continental-shelf waveguide containing random three-dimensional internal waves. The modeled coherence time scale of narrow band low-frequency acoustic field fluctuations after propagating through a continental-shelf waveguide is shown to decay with a power-law of range to the −1/2 beyond roughly 1 km, decrease with increasing internal wave energy, to be consistent with measured acoustic coherence time scales. The model should provide a useful prediction of the acoustic coherence time scale as a function of internal wave energy in continental-shelf environments. The acoustic coherence time scale is an important parameter in remote sensing applications because it determines (i) the time window within which standard coherent processing such as matched filtering may be conducted, and (ii) the number of statistically independent fluctuations in a given measurement period that determines the variance reduction possible by stationary averaging.
The effect of rocking stapes motions on the cochlear fluid flow and on the basilar membrane motion
Authors: Edom Elisabeth , Obrist Dominik , Henniger Rolf , Kleiser Leonhard , Sim Jae Hoon , Huber Alexander M.
Published: November 2013

The basilar membrane (BM) and perilymph motion in the cochlea due to rocking stapes motion (RSM) and piston-like stapes motion (PSM) is modeled by numerical simulations. The full Navier–Stokes equations are solved in a two-dimensional box geometry. The BM motion is modeled by independent oscillators using an immersed boundary technique. The traveling waves generated by both stimulation modes are studied. A comparison of the peak amplitudes of the BM motion is presented and their dependence on the frequency and on the model geometry (stapes position and cochlear channel height) is investigated. It is found that the peak amplitudes for the RSM are lower and decrease as frequency decreases whereas those for the PSM increase as frequency decreases. This scaling behavior can be explained by the different mechanisms that excite the membrane oscillation. Stimulation with both modes at the same time leads to either a slight increase or a slight decrease of the peak amplitudes compared to the pure PSM, depending on the phase shift between the two modes. While the BM motion is dominated by the PSM mode under normal conditions, the RSM may lead to hearing if no PSM is present or possible, e.g., due to round window atresia.
Hearing tongue loops: Perceptual sensitivity to acoustic signatures of articulatory dynamics
Authors: Nam Hosung , Mooshammer Christine , Iskarous Khalil , Whalen D. H.
Published: November 2013

Previous work has shown that velar stops are produced with a forward movement during closure, forming a forward (anterior) loop for a VCV sequence, when the preceding vowels are back or mid. Are listeners aware of this aspect of articulatory dynamics? The current study used articulatory synthesis to examine how such kinematic patterns are reflected in the acoustics, and whether those acoustic patterns elicit different goodness ratings. In Experiment I, the size and direction of loops was modulated in articulatory synthesis. The resulting stimuli were presented to listeners for a naturalness judgment. Results show that listeners rate forward loops as more natural than backward loops, in agreement with typical productions. Acoustic analysis of the synthetic stimuli shows that forward loops exhibit shorter and shallower VC transitions than CV transitions. In Experiment II, three acoustic parameters were employed incorporating F3-F2 distance, transition slope, and transition length to systematically modulate the magnitude of VC and CV transitions. Listeners rated the naturalness in accord with those of Experiment I. This study reveals that there is sufficient information in the acoustic signature of “velar loops” to affect perceptual preference. Similarity to typical productions seemed to determine preferences, not acoustic distinctiveness.
Acoustic characterization and contrast imaging of microbubbles encapsulated by polymeric shells coated or filled with magnetic nanoparticles
Authors: Sciallero Claudia , Grishenkov Dmitry , Kothapalli Satya V. V. N. , Oddo Letizia , Trucco Andrea
Published: November 2013

The combination of superparamagnetic iron oxide nanoparticles with polymeric air-filled microbubbles is used to produce two types of multimodal contrast agents to enhance medical ultrasound and magnetic resonance imaging. The nanoparticles are either covalently linked to the shell or physically entrapped into the shell. In this paper, the characterization of the acoustic properties (backscattered power, fracturing pressure, attenuation and dispersion of the ultrasonic wave) and ultrasound imaging of the two types of magnetic microbubbles are presented. In vitro B-mode images are generated using a medical ultrasound scanner by applying a nonconventional signal processing technique that is suitable to detect polymeric bubbles and based on the combination of multipulse excitation and chirp coding. Even if both types of microbubbles can be considered to be effective ultrasound contrast agents, the different structure of the shell loaded with nanoparticles has a pronounced effect on the echogenicity and the detection sensitivity of the imaging technique. The best results are obtained using microbubbles that are externally coated with nanoparticles. A backscattered power of 20 dB was achieved at lower concentration, and an increment of 8 dB in the contrast-to-tissue ratio was observed with respect to the more rigid microbubbles with particles entrapped into the shell.
Comparisons of two effective medium approaches for predicting sound scattering by periodic arrays of elastic shells
Authors: Umnova Olga , Krynkin Anton , Boon Chong Alvin Yung , Taherzadeh Shahram , Attenborough Keith
Published: November 2013

Two effective medium models are presented and used to predict complex reflection and transmission coefficients of finite periodic arrays of resonant elastic shells as well as their effective density and bulk modulus at low frequencies. Comparisons with full multiple scattering theory and measurements show that the self-consistent model fails to correctly predict the shape of the transmission/reflection curves when scatterer resonances are close to the first Bragg bandgap. The low frequency grating model, which neglects the evanescent modes and considers scattered wave propagation only in the same direction as the incident one, gives a much better agreement with both measurements and the full multiple scattering theory. Moreover, because it does not require the wavelength to strongly exceed the size of scatterers, the model gives reliable predictions even at frequencies around the first periodicity related bandgap. In contrast to the self-consistent model, the low frequency grating model is applicable when the resonant scatterers have more than two low frequency resonances.
Perception of spectrally degraded reflexives and pronouns by children
Authors: Başkent Deniz , van Rij Jacolien , Ng Zheng Yen , Free Rolien , Hendriks Petra
Published: November 2013

Speech perception skills in cochlear-implant users are often measured with simple speech materials. In children, it is crucial to fully characterize linguistic development, and this requires linguistically more meaningful materials. The authors propose using the comprehension of reflexives and pronouns, as these specific skills are acquired at different ages. According to the literature, normal-hearing children show adult-like comprehension of reflexives at age 5, while their comprehension of pronouns only reaches adult-like levels around age 10. To provide normative data, a group of younger children (5 to 8 yrs old), older children (10 and 11 yrs old), and adults were tested under conditions without or with spectral degradation, which simulated cochlear-implant speech transmission with four and eight channels. The results without degradation confirmed the different ages of acquisition of reflexives and pronouns. Adding spectral degradation reduced overall performance; however, it did not change the general pattern observed with non-degraded speech. This finding confirms that these linguistic milestones can also be measured with cochlear-implanted children, despite the reduced quality of sound transmission. Thus, the results of the study have implications for clinical practice, as they could contribute to setting realistic expectations and therapeutic goals for children who receive a cochlear implant.
Measuring and optimizing clarity in large and small spaces
Authors: Griesinger David H.
Published: November 2013

Psychologists know that sounds perceived as close to a listener hold attention and are easier to parse and to remember than sounds perceived as further away. But current measures for clarity are blind to the vital importance of sonic closeness in the transfer of information in enclosed spaces. Recent work in the neurology of the inner ear is illuminating the mechanisms by which the ear separates simultaneous sounds from separate sources, as well as the “closeness” of each source. Knowledge of these mechanisms allows us to predict how this ability is lost in the presence of reflections and noise, and to predict a number of ways that real clarity can be measured and optimized in classrooms, lecture halls, and performance venues of all types. This paper will describe and demonstrate how reflections degrade the closeness or clarity of sounds, and how this degradation can be prevented or ameliorated. Examples of old and new spaces with either excellent or poor clarity will be presented, along with a few examples of recent improvements to existing halls.
The effect of using matched, but not individualized, head related transfer functions on the subjective evaluation of auralizations
Authors: Neal Matthew , Vigeant Michelle C.
Published: November 2013

Head related transfer functions (HRTFs) are a key component when creating auralizations used in subjective concert hall studies. An average HRTF, rather than an individualized HRTF, is often used when creating auralizations, which can lead to front-back ambiguity and reduced out-of-head sound localization. The goal of this study was to determine how the choice of HRTF can impact subjective impression of various concert hall acoustic qualities from auralizations. Using 10 HRTFs from the CIPIC database, the best and worst case HRTFs were determined for each test subject, based on out-of-head localization. For the main test, auralizations were created using these two HRTFs, along with an average HRTF. The subjects’ task was to evaluate the auralizations based upon concert hall acoustics characteristics, such as reverberance and listener envelopment. Before participating in the main part of the study, the subjects were required to complete a series of training sessions. Test subjects were limited to trained musicians and those who met a 15 dB hearing level requirement. The resulting data were analyzed to determine the significance of the differences between the three cases. The results from the listening tests and the statistical analysis will be presented. [Work supported by NSF Grant 1302741.]
The acoustics of the catacombs of “San Callisto” in Rome
Authors: Trematerra Amelia , Iannace Gino
Published: November 2013

The present study shows the acoustic properties of the catacombs of “St. Callisto” in Rome. Same acoustic measurements were made to understand which type of religious functions could have been celebrated in them, in particular, if they were spoken or sung. The catacombs were places of burial, but they were also places of reunions and visits to the graves of the martyrs. The catacombs are places for burial, diffused in the different religions of the different zones of Europe and Mediterranean Asia, not only Christian, even if they reached the maximum diffusion with the Christianity, the presence of the catacombs in these places it is due to the fact that the subsoil is easily excavatable. The catacombs were generally built through the realization of burrows, with corridors that connected all the “cubicles,” rooms with a regular plant in which the burial happened. The acoustic measurements were carried out with an explosion of a balloon toy, with a microphone connected to a computer were measured the impulse response. The microphones were in different points of the corridors and in the “cubicles.” The T30 measured values is short, for the presence the catacombs tuff walls.
Highlighting pros and cons of abundance estimation using passive acoustic data: monitoring fin whales (Balaenoptera physalus) off the southern Portuguese coast using seismometers
Authors: Harris Danielle , Marques Tiago , Matias Luis , Mellinger David K. , Küsel Elizabeth T. , Thomas Len
Published: November 2013

Monitoring marine mammals using passive acoustic sensors is increasingly popular. Generating abundance estimates from acoustic data would be extremely useful for marine environment stakeholders. To achieve accurate abundance estimates, there are three broad areas to consider: (1) survey design, (2) data collection and processing, and (3) data analysis. Here, we use an analysis of fin whale (Balaenoptera physalus) calls recorded on ocean bottom seismometers (OBSs) to discuss the main advantages, disadvantages and considerations of abundance estimation using acoustic data. The OBS array was deployed for one year (2007–2008) and demonstrates how an opportunistic dataset can meet survey design requirements. Ranges to detected calls (detected with a matched filter) were estimated using the seismological three-component method. Point transect sampling, an abundance estimation method, was then used to estimate average call density. Animal density or abundance could not be estimated because the appropriate average calling rate was unknown. Finally, spatiotemporal patterns of call density were modeled. This dataset has also allowed new methods development—a method that estimates abundance as a function of total energy in a species’ frequency band has been developed. In summary, abundance estimation using acoustic data is possible but challenging, and improved knowledge of vocal behavior is essential.
Transmission characteristics of Arctic pinniped vocalizations through ice
Authors: Denes Samuel L. , Hager Carl , Miksis-Olds Jennifer L.
Published: November 2013

Arctic pinniped vocalizations occur in an environment where acoustic coupling between water, air, and ice must be considered in propagation effects. A low amplitude propagation experiment was conducted to measure the transmission characteristics of water borne acoustic signals through ice and into air. The signals used were inspired by arctic pinniped vocalizations. Signals included impulses, frequency modulated downsweeps, and continuous frequency tones. An array of 12 elements including 6 hydrophones, 3geophones, and 3 microphones were deployed off the coast of Barrow, Alaska, in March of 2012. Three stations consisting of two hydrophones, one geophone and one microphone were arranged linearly in one ice pan with a source speaker placed endfire and broadside. Ice thickness varied from 1.5 to 2.5 m between the receiver locations. Measured transmission characteristics of each of the signals are analyzed as a function of distance from the source and thickness of ice. Received levels are compared with estimates from a wavenumber integration propagation model. Communication ramifications from changing Arctic ice conditions will be discussed.
Comparison of remote ranging techniques for bowhead whale calls in a dispersive underwater sound channel
Authors: Abadi Shima , Thode Aaron M. , Dowling David R.
Published: November 2013

Locating and monitoring marine mammals near anthropogenic sound sources are important tasks with both environmental and operational consequences. This presentation describes how mode filtering (MF) or a blind-deconvolution technique (synthetic time reversal, STR) can be used to determine the range of bowhead whale calls from a single linear vertical array in a dispersive underwater sound channel. The results are based on environmental parameters at the array location, and simulations and ocean recordings of natural whale calls with a nominal bandwidth from 50 to 500 Hz. The passive listening experiments were conducted in the coastal waters near Kaktovik, Alaska, with a 12-element vertical array nominally spanning the middle 60% of the water column. It was deployed in 55-m-deep water alongside distributed arrays of Directional Autonomous Seafloor Acoustics Recorders (DASARs) arranged in triangular grids used to horizontally localize whale calls. A total of 18 naturally occurring whale calls were considered. The estimated call-to-array ranges determined from mode filtering and STR are compared with reference triangulation results from the DASARs. The vertical-array ranging results are generally within ±10% of the DASARs results with the STR results being slightly more accurate than those from mode filtering. [Sponsored by ONR and Shell.]
Protocols for acoustic devices on cabled ocean observatories
Authors: Dewey Richard K. , Mihaly Steve , Dakin Tom
Published: November 2013

Cabled ocean observatories offer an unprecedented opportunity for marine acoustic devices. With continuous power and high bandwidth, long-term broadband measurements from both passive and active systems are possible over a wide range of oceanographic environments. In particular, the cabled ocean observatories VENUS and NEPTUNE operated by Ocean Networks Canada offer a unique set of possibilities for acoustic research, ranging from littoral to mid-ocean ridge installations. Since 2006 fiber optic telecommunication cables have provided high power and up to GB data rates from nine distributed observatory Nodes across marine provinces, which include fjords, tidal straits, river deltas, continental shelves, slopes and rises, abyssal plains, and spreading margins. Experience from passive hydrophones as well as both mono- and bi-static active systems including echo-sounders, sonars, and many acoustic Doppler current devices will be discussed. This paper will review our experiences, provide examples, and propose protocols, or at least our suggested best practices, for many active and passive acoustic devices, including calibration, configuration, interference reduction techniques, bandwidth considerations, data handling, and data analysis and delivery methods.
Remote performance assessment of cabled observatory hydrophone systems
Authors: Merchant Nathan D. , Dakin D. Tom , Dorocicz John , Blondel Philippe
Published: November 2013

The increasing expansion of cabled undersea observatories worldwide presents a unique opportunity to develop and deploy hydrophone systems for long-term monitoring of underwater noise. Among the first such observatories, the NEPTUNE and VENUS networks operated by Ocean Networks Canada (ONC) have been pioneering in their implementation of acoustic monitoring systems and are projected to continue operation with an anticipated lifetime of 25 years. One challenge that arises from decades-long deployments is the need to assess the consistency of data quality from operational instruments. Since the replacement or in situ calibration of instruments can be costly and problematic, it is expedient if such performance assessment can be conducted remotely. Here, we present methods of detecting deterioration in the performance of cabled hydrophone systems and assessing the suitability of the dynamic range to the prevailing noise conditions. Approaches are proposed based on tracking variability in the primary mode, detection and classification of persistent tonal components, and automatic detection of dynamic range exceedance. Scenarios based on data from ONC observatories are presented.