bluuebunny/crossref_metadata_2025 huggingface dataset:
Nestin‐expressing cells in the gut give rise to enteric neurons and glial cells
Authors: Belkind‐Gerson J. , Carreon‐Rodriguez A. , Benedict L. Andrew , Steiger C. , Pieretti A. , Nagy N. , Dietrich J. , Goldstein A. M.
Published: September 2012

Background  Neuronal stem cells (NSCs) are promising for neurointestinal disease therapy. Although NSCs have been isolated from intestinal musclularis, their presence in mucosa has not been well described. Mucosa‐derived NSCs are accessible endoscopically and could be used autologously. Brain‐derived Nestin‐positive NSCs are important in endogenous repair and plasticity. The aim was to isolate and characterize mucosa‐derived NSCs, determine their relationship to Nestin‐expressing cells and to demonstrate their capacity to produce neuroglial networks in vitro and in vivo.

Methods  Neurospheres were generated from periventricular brain, colonic muscularis (Musc), and mucosa–submucosa (MSM) of mice expressing green fluorescent protein (GFP) controlled by the Nestin promoter (Nestin‐GFP). Neuronal stem cells were also grown as adherent colonies from intestinal mucosal organoids. Their differentiation potential was assessed using immunohistochemistry using glial and neuronal markers. Brain and gut‐derived neurospheres were transplanted into explants of chick embryonic aneural hindgut to determine their fate.

Key Results  Musc‐ and MSM‐derived neurospheres expressed Nestin and gave rise to cells of neuronal, glial, and mesenchymal lineage. Although Nestin expression in tissue was mostly limited to glia co‐labelled with glial fibrillary acid protein (GFAP), neurosphere‐derived neurons and glia both expressed Nestin in vitro, suggesting that Nestin+/GFAP+ glial cells may give rise to new neurons. Moreover, following transplantation into aneural colon, brain‐ and gut‐derived NSCs were able to differentiate into neurons.

Conclusions & Inferences  Nestin‐expressing intestinal NSCs cells give rise to neurospheres, differentiate into neuronal, glial, and mesenchymal lineages in vitro, generate neurons in vivo and can be isolated from mucosa. Further studies are needed for exploring their potential for treating neuropathies.
New insights into the brain involvement in patients with Crohn’s disease: a voxel‐based morphometry study
Authors: Agostini A. , Benuzzi F. , Filippini N. , Bertani A. , Scarcelli A. , Farinelli V. , Marchetta C. , Calabrese C. , Rizzello F. , Gionchetti P. , Ercolani M. , Campieri M. , Nichelli P.
Published: September 2012

Background  Crohn’s disease (CD) is a chronic intestinal disorder characterized by overproduction of inflammatory cytokines and recurrent abdominal pain. Recently, brain morphological abnormalities in the pain matrix were found in patients with chronic pain disorders including irritable bowel syndrome. To investigate potential structural brain changes associated with CD, we used magnetic resonance imaging (MRI). Furthermore, we tested whether in patients gray matter (GM) volumes correlated with disease duration.

Methods  Eighteen CD patients in remission and 18 healthy controls underwent structural MRI. Voxel‐based morphometry (VBM) is a fully automated technique allowing identification of regional differences in the amount of GM enabling an objective analysis of the whole brain between groups of subjects. VBM was used for comparisons and correlation analysis.

Key Results  With respect to controls, CD patients exhibited decreased GM volumes in portion of the frontal cortex and in the anterior midcingulate cortex. Disease duration was negatively correlated with GM volumes of several brain regions including neocortical and limbic areas.

Conclusions & Inferences  Crohn’s disease is associated with brain morphological changes in cortical and subcortical structures involved in nociception, emotional, and cognitive processes. Our findings provide new insight into the brain involvement in chronic inflammatory bowel disorders.
Postoperative vomiting in pediatric oncologic patients: prediction by a fuzzy logic model
Authors: Bassanezi Betina S.B. , de Oliveira‐Filho Antônio G. , Jafelice Rosana S.M. , Bustorff‐Silva Joaquim M. , Udelsmann Artur
Published: September 2012

Objective

To report a fuzzy logic mathematical model to predict postoperative vomiting (POV) in pediatric oncologic patients and compare with preexisting scores.

Background

Although POV has a high incidence in children and may decrease parental satisfaction after surgeries, there is only one specific score that predicts POV in children: the Eberhart's score. In this study, we report a fuzzy model that intends to predict the probability of POV in pediatric oncologic patients. Fuzzy logic is a mathematical theory that recognizes more than simple true and false values and takes into account levels of continuous variables such as age or duration of the surgery. The fuzzy model tries to account for subjectiveness in the variables.

Methods

Preoperative potential risk factors for POV in 198 children (0–19 year old) with malignancies were collected and analyzed. Data analysis was performed with the chi‐square test and logistic regression to evaluate probable risk factors for POV. A system based on fuzzy logic was developed with the risk factors found in the logistic regression, and a computational interface was created to calculate the probability of POV.

Results

The model showed a good performance in predicting POV. After the analysis, the model was compared with Eberhart's score in the same population and showed a better performance.

Conclusions

The fuzzy score can predict the chance of POV in children with cancer with good accuracy, allowing better planning for postoperative prophylaxis of vomiting. The computational interface is available for free download at the internet and is very easy to use.
Expression of the Chlamydomonas reinhardtii Sedoheptulose‐1,7‐bisphosphatase in Dunaliella bardawil leads to enhanced photosynthesis and increased glycerol production
Authors: Fang Lei , Lin Hui Xin , Low Chin Seng , Wu Mei Hui , Chow Yvonne , Lee Yuan Kun
Published: September 2012

Bioengineering of photoautotrophic microalgae into CO2 scrubbers and producers of value‐added metabolites is an appealing approach in low‐carbon economy. A strategy for microalgal bioengineering is to enhance the photosynthetic carbon assimilation through genetically modifying the photosynthetic pathways. The halotolerant microalgae Dunaliella posses an unique osmoregulatory mechanism, which accumulates intracellular glycerol in response to extracellular hyperosmotic stresses. In our study, the Calvin cycle enzyme sedoheptulose 1,7‐bisphosphatase from Chlamydomonas reinhardtii (CrSBPase) was transformed into Dunaliella bardawil, and the transformant CrSBP showed improved photosynthetic performance along with increased total organic carbon content and the osmoticum glycerol production. The results demonstrate that the potential of photosynthetic microalgae as CO2 removers could be enhanced through modifying the photosynthetic carbon reduction cycle, with glycerol as the carbon sink.
Work–Family Conflict and Flexible Work Arrangements: Deconstructing Flexibility
Authors: Allen Tammy D. , Johnson Ryan C. , Kiburz Kaitlin M. , Shockley Kristen M.
Published: September 2012

Workplace flexibility has been a topic of considerable interest to researchers, practitioners, and public policy advocates as a tool to help individuals manage work and family roles. In this study, meta‐analysis is used to clarify what is known about the relationship between flexible work arrangements and work–family conflict by deconstructing the flexibility construct. We found that the direction of work–family conflict (work interference with family vs. family interference with work) and the specific form of flexibility (flextime vs. flexplace; use vs. availability) make a difference in the effects found. Overall, the significant effects were small in magnitude.
Boundary Conditions of the High‐Investment Human Resource Systems‐Small‐Firm Labor Productivity Relationship
Authors: Chadwick Clint , Way Sean A. , Kerr Gerry , Thacker James W.
Published: September 2012

Although a few published, multiindustry, firm‐level, empirical studies have linked systems of high‐investment or high‐performance human resource management practices to enhanced small‐firm performance, this stream of strategic human resource management research is underdeveloped and equivocal. Accordingly, in this study, we use a sample of for‐profit, private‐sector, small Canadian firms with fewer than 100 employees from a variety of industry sectors to examine boundary conditions of the relationship between firm‐level high‐investment human resource systems and objective small‐firm labor productivity. Congruent with contingency theory, this study's results indicate that the extent and nature of the influence of high‐investment human resource systems on objective small‐firm labor productivity is contingent on internal (differentiation strategy and firm capital intensity) and external boundary conditions (industry dynamism and industry growth). Implications and limitations of this research study as well as avenues for future research are discussed.
Expanding and Reconceptualizing Aberrant Personality at Work: Validity of Five‐Factor Model Aberrant Personality Tendencies to Predict Career Outcomes
Authors: Wille Bart , De Fruyt Filip , De Clercq Barbara
Published: September 2012

This study proposes and tests an alternative methodology to conceptualize and assess aberrant personality tendencies at work beyond the dark triad. A sample of college alumni (N= 247) were administered the NEO PI‐R prior to entering the labor market and 15 years later when their professional careers had unfolded. Drawing on the dimensional perspective on personality functioning, 6 five‐factor model (FFM) aberrant compounds were computed as indicators of aberrant personality tendencies. As expected, FFM aberrant personality tendencies were highly stable across time, with test–retest correlations ranging from .61 (Narcissistic) to .73 (avoidant). With regard to predictive validity, borderline, schizotypal, and avoidant tendencies were negatively associated with extrinsic and intrinsic career outcomes. The obsessive‐compulsive tendency was largely unrelated to career outcomes, whereas individuals with antisocial and narcissistic characteristics tended toward higher hierarchical and financial attainment. In addition, relative importance analyses indicated that (a) FFM aberrant personality tendencies showed incremental validity in the prediction of career outcomes beyond FFM general traits, and that (b) both FFM general and FFM aberrant personality tendencies are important predictors when considered jointly. It is concluded that FFM aberrant personality tendencies suggest interesting avenues for personnel psychologists to form new linear combinations of FFM facets, complementing FFM general domains.
The influence of birth date and place of development on youth sport participation
Authors: Turnnidge J. , Hancock D. J. , Côté J.
Published: September 2012

Previous research highlights the critical role that contextual factors play in shaping athlete development. The purpose of the present study was to investigate two of these contextual factors: birth date (known as the relative age effect, RAE) and city of development as determinants of participation in a sample of youth ice hockey players. The sample included 146 424 athletes registered with Ontario youth ice hockey between the 2004 and 2010 seasons. Chi‐square statistics determined a significant RAE in youth ice hockey. Findings also revealed a significant association between small cities of development and increased youth ice hockey participation. Finally, there was no evidence of an interaction between relative age and city of development. The characteristics of smaller communities that may facilitate sport participation across all youth are discussed, along with recommendations for future research.
Fluid pressure, stress field and propagation style of coalescing thrusts from the analysis of the 20 May 2012 ML 5.9 Emilia earthquake (Northern Apennines, Italy)
Authors: Ventura Guido , Di Giovambattista Rita
Published: September 2012

Terra Nova, 25, 72–78, 2013

Two major earthquakes of ML 5.9 and 5.8 and hundreds of aftershocks affected the Emilia region (Po Plain, Italy) between 20 May and June 2012. The events concentrate in the uppermost 10 km of the crust with few events up to 30 km. Two buried, sub‐parallel N100°E striking thrusts of the Northern Apennines belt are reactivated. These thrusts coalesce at the interface between the metamorphic basement of the belt and the overlying, about 10‐km thick, sedimentary succession. Focal mechanisms indicate a compressive stress field with a sub‐horizontal, roughly N‐S striking σ1. This stress field is consistent with active shortening in Northern Apennines. Suprahydrostatic pore pressure and σ1 ∼ σ2≠σ3 are required to reactivate the thrusts. The involved fluids could be gas and brines hosted in the folded sedimentary successions. The time and spatial evolution of the seismicity indicates a foreland to hinterland propagation of the ruptures and a thin‐skinned deformation of Northern Apennines.
3D displacement maps of the 2009 L’Aquila earthquake (Italy) by applying the SISTEM method to GPS and DInSAR data
Authors: Guglielmino Francesco , Anzidei Marco , Briole Pierre , Elias Panagiotis , Puglisi Giuseppe
Published: September 2012

Terra Nova, 25, 79–85, 2013

We present an application of the novel SISTEM approach, to obtain the dense 3D ground deformation pattern produced by the April 6, 2009, Mw 6.3 L’Aquila earthquake. This event, characterized by a SW‐dipping normal fault with thousands of foreshocks and aftershocks located in the depth range 5–15 km, is the most destructive to have struck the Abruzzo region since the major 1703 seismic sequence. The surface deformation, revealed by the SISTEM through the integration of GPS with interferometric measurements from the ENVISAT and ALOS satellites, shows a deformed area extending towards SE along the Aterno valley, in agreement with seismological and other geodetic observations. We inverted the SISTEM results using an optimization algorithm based on the genetic algorithm, providing an accurate spatial characterization of ground deformation. Our results improve previous kinematic solutions for the Paganica fault and allow identification of additional faults that have contributed to the observed complex ground deformation pattern.
Infectious complications following allogeneic stem cell transplantation: reduced‐intensity vs. myeloablative conditioning regimens
Authors: Kim S.‐H. , Kee S.Y. , Lee D.‐G. , Choi S.‐M. , Park S.H. , Kwon J.‐C. , Eom K.‐S. , Kim Y.‐J. , Kim H.‐J. , Lee S. , Min C.‐K. , Kim D.‐W. , Choi J.‐H. , Yoo J.‐H. , Lee J.‐W. , Min W.‐S.
Published: September 2012

Background

In allogeneic stem cell transplantation (allo‐SCT), reduced‐intensity conditioning (RIC) is known for producing less regimen‐related toxicity. However, whether or not RIC reduces the risk for infection and infection‐related mortality (IRM) remains controversial.

Methods

We retrospectively analyzed infectious episodes and IRMs after allo‐SCTs by time period and by the intensity of the conditioning regimen (RIC [n = 81] vs. myeloablative conditioning, MAC [n = 150]).

Results

The cumulative incidence of any kind of infection was lower in the RIC group through the entire period (72% vs. 87%; P = 0.007). The onset of infections was deferred in the RIC group as compared with the MAC group (P = 0.012). Bacteremia occurred less frequently in the RIC group through the entire period (5% vs. 14%; P = 0.044). However, the incidences of cytomegalovirus reactivation and disease, herpes zoster, virus‐associated hemorrhagic cystitis, and invasive fungal infection were not different between the two groups. Furthermore, there was no difference in relapse‐free survival and IRM between the two conditioning regimens.

Conclusion

Careful monitoring and appropriate preventive/therapeutic strategies for infectious complications, comparable to those for allo‐SCT recipients with MAC, should also be applied to those with RIC, especially after engraftment.
Bordetella holmesii bacteremia in a renal transplant recipient: emergence of a new pathogen
Authors: Chambaraud T. , Dickson Z. , Ensergueix G. , Barraud O. , Essig M. , Lacour C. , Allard J. , Bocquentin F. , Aldigier J.C. , Rerolle J.P.
Published: September 2012

Bordetella holmesii is a gram‐negative rod that was initially identified in 1995. It causes bacteremia, pneumonia, and endocarditis mostly in patients with anatomical or functional asplenia. We report here, to the best of our knowledge, the first case of B. holmesii bacteremia in a renal transplant recipient following rituximab therapy for recurrence of membranoproliferative glomerulonephritis.
Development and Comparison of Laplace Domain and State-Space Models of a Half-Car With Flexible Body (ESDA2010–24518)
Authors: Michael Van Auken R.
Published: September 2012

Math models of wheeled ground vehicle dynamics, including flexible body effects, have been the subject of research and development for many years. These models are typically based on a finite system of simultaneous ordinary differential equations (e.g., state-space models). Higher order models that include flexible body effects offer improved accuracy over a wider frequency range than lower order rigid body models; however, higher order models are typically more sensitive to uncertainties in the model parameters and have increased computational requirements. Lower order models with the desired accuracy may be achieved by model reduction of higher order models. A new more general infinite dimensional Laplace transfer function is derived for beam bending governed by a fourth order wave equation. The resulting infinite dimensional transfer functions for beam bending are then used to develop a transfer function model of a “half-car” with a flexible body. The infinite dimensional transfer function of the half-car model is then used to assess the accuracy of the state-space models. Differences between the models due to model reduction are compared to theoretical upper bounds.
Measurement of Total Hemispherical Emissivity Using Vacuum Guarded Hot Plate
Authors: Kim Jongmin , Jang Choongyo , Song Tae-Ho
Published: September 2012

In this paper, a new measurement method for the total hemispherical emissivity of surfaces is introduced. A vacuum guarded hot plate apparatus is developed and it is employed for the emissivity measurement. Al, Ag, Au, and Ni coatings and STS 304 plate are used as the specimen. Measured total hemispherical emissivities are 0.05–0.24 with 8.1% uncertainty at most. This proves the reliability of current method even for highly reflective surfaces.
Three-Dimensional Inverse Heat Transfer in a Composite Target Subject to High-Energy Laser Irradiation
Authors: Zhou Jianhua , Zhang Yuwen , Chen J. K. , Feng Z. C.
Published: September 2012

A new numerical model is developed to simulate the 3D inverse heat transfer in a composite target with pyrolysis and outgassing effects. The gas flow channel size and gas addition velocity are determined by the rate equation of decomposition chemical reaction. The thermophysical properties of the composite considered are temperature-dependent. A nonlinear conjugate gradient method (CGM) is applied to solve the inverse heat conduction problem for high-energy laser-irradiated composite targets. It is shown that the front-surface temperature can be recovered with satisfactory accuracy based on the temperature/heat flux measurements on the back surface and the temperature measurement at an interior plane.
Experimental Validation for the dp/dt Assumption of Heat Exchangers in Vapor Compression Refrigeration Cycles
Authors: Li Pengfei , Seem John E. , Li Yaoyu
Published: September 2012

Calculation of time derivatives of refrigerant pressures is important for dynamic simulation of heat exchangers in vapor compression cycles, i.e., typically the condenser and evaporator. This technical brief presents an experimental study on the pressure transient for the condenser and evaporator of a screw chiller with R134a, along with the analysis for the associated time derivatives. The experimental results from eight test cases suggest that the time derivatives of the condenser and evaporator pressures at their inlet are extremely close to those at the respective outlets. This observation can thus justify the key assumption of equal time derivatives of pressures in the dynamic modeling of heat exchangers, which in consequence improves the numerical efficiency and/or convergence, especially for large and complex thermal-fluid systems.
Characterization of the Acoustic Interactions in a Two-Stage Multi-Injection Combustor Fed With Liquid Fuel
Authors: Providakis Theodore , Zimmer Laurent , Scouflaire Philippe , Ducruix Sébastien
Published: September 2012

Burners operating in lean premixed prevaporized (LPP) regimes are considered as good candidates to reduce pollutant emissions from gas turbines. Lean combustion regimes result in lower burnt gas temperatures and therefore a reduction on the NOx emissions, one of the main pollutant species. However, these burners usually show strong flame dynamics, making them prone to various stabilization problems (combustion instabilities, flashback, flame extinction). To face this issue, multi-injection staged combustion can be envisaged. Staging procedures enable fuel distribution control, while multipoint injections can lead to a fast and efficient mixing. A laboratory-scale staged multipoint combustor is developed in the present study, in the framework of LPP combustion, with an injection device close to the industrial one. Using a staging procedure between the primary pilot stage and the secondary multipoint one, droplet and velocity field distributions can be varied in the spray that is formed at the entrance of the combustion chamber. The resulting spray and flame are characterized using OH-planar laser induced fluorescence, high speed particle image velocimetry, and phase Doppler anemometry measurements. Three staging values, corresponding to three different flame stabilization processes, are analyzed, while power is kept constant. It is shown that mean values are strongly influenced by the fuel distribution and the flame position. Using adequate postprocessing, the interaction between the acoustic field and the droplet behavior is characterized. Spectral analysis reveals a strong acoustic-flame coupling leading to a low frequency oscillation of both the velocity field and the spray droplet distribution. In addition, acoustic measurements in the feeding line show that a strong oscillation of the acoustic field leads to a change in fuel injection, and hence droplet behavior.
Hybrid Solar System for Decentralized Electric Power Generation and Storage
Authors: Hotz Nico
Published: September 2012

The present study investigates the feasibility, efficiency, and system design of a hybrid solar system generating electric power for stationary applications such as residential buildings. The system is fed by methanol and combines methanol steam reforming and proton exchange membrane (PEM) fuel cells with solar collectors to generate the required heat for the steam reforming. The synergies of these technologies lead to a highly efficient system with significantly larger power densities compared to conventional systems and generate tremendous advantages in terms of installation and operation costs. The present investigation describes the entire proposed system and its components and presents first analytical, numerical, and experimental results of a larger project to prove the feasibility of such a system by analyzing first a bench test demonstrator generating around 10 W of electric power and finally a prototype for an entire single-family household. It is shown that the methanol-to-electricity efficiency of the entire system is above 50%.
Via-hole fabrication for III-V triple-junction solar cells
Authors: Zhao Yuning , Fay Patrick , Wibowo Andre , Liu Jianhong , Youtsey Chris
Published: September 2012

Backside contact technology for InGaP/GaAs/InGaAs inverted metamorphic (IMM) triple junction solar cells is a potential avenue for achieving significant improvements in solar cell efficiency. To implement such a backside contact technology in IMM triple-junction III-V solar cells, through-cell via-hole fabrication is a key fabrication process. To address this challenge, a three-step etching process has been developed for via-hole fabrication. The etching process includes two Cl2/Ar inductively coupled plasma reactive ion etching steps, followed by a selective wet etch to form via-holes with excellent sidewall anisotropy and etch morphology. The process enables fabrication of backside contact photovoltaic cells for improved efficiency.
Template-dependent nucleation of metallic droplets
Authors: Nothern Denis M. , Millunchick Joanna M.
Published: September 2012

We experimentally investigate the nucleation behavior of metallic gallium droplets deposited on gallium arsenide substrates and calculate the critical cluster size for various growth conditions and substrate templating. We find that the critical cluster size for liquid Ga on GaAs is approximately six atoms. Deposition on substrates templated with arrays of holes does not result in significant ordering of the droplets at the array dimensions studied here, but does result in an apparent reduction of the critical cluster size due to heterogeneous nucleation.
Dosimetric perturbations due to an implanted cardiac pacemaker in MammoSite® treatment
Authors: Sung Wonmo , Kim Siyong , Kim Jung‐in , Lee Jae‐gi , Shin Young‐Joo , Jung Jae‐Yong , Ye Sung‐Joon
Published: September 2012

Purpose:

To investigate dose perturbations for pacemaker‐implanted patients in partial breast irradiation using high dose rate (HDR) balloon brachytherapy.

Methods:

Monte Carlo (MC) simulations were performed to calculate dose distributions involving a pacemaker in Ir‐192 HDR balloon brachytherapy. Dose perturbations by varying balloon‐to‐pacemaker distances (BPD = 50 or 100 mm) and concentrations of iodine contrast medium (2.5%, 5.0%, 7.5%, and 10.0% by volume) in the balloon were investigated for separate parts of the pacemaker (i.e., battery and substrate). Relative measurements using an ion‐chamber were also performed to confirm MC results.

Results:

The MC and measured results in homogeneous media without a pacemaker agreed with published data within 2% from the balloon surface to 100 mm BPD. Further their dose distributions with a pacemaker were in a comparable agreement. The MC results showed that doses over the battery were increased by a factor of 3, compared to doses without a pacemaker. However, there was no significant dose perturbation in the middle of substrate but up to 70% dose increase in the substrate interface with the titanium capsule. The attenuation by iodine contrast medium lessened doses delivered to the pacemaker by up to 9%.

Conclusions:

Due to inhomogeneity of pacemaker and contrast medium as well as low‐energy photons in Ir‐192 HDR balloon brachytherapy, the actual dose received in a pacemaker is different from the homogeneous medium‐based dose and the external beam‐based dose. Therefore, the dose perturbations should be considered for pacemaker‐implanted patients when evaluating a safe clinical distance between the balloon and pacemaker.
Simple interactive virtual auralizations as educational tools
Authors: Barnobi Christopher L.
Published: September 2012

This presentation provides an overview and demonstration of some `classic' acoustic phenomena using a computer simulation. The computer program provides a visual rendering of an environment with a source and receiver. By allowing the user to vary some of the parameters of the environment, a user can see and hear the differences in spaces by changing the surroundings. The goal is to highlight the well known environmental factors that impact sound such as volume in a room. A variety of parameters and environments will be explored.
Finite difference simulation methods as an educational tool
Authors: Botts Jonathan , Xiang Ning , Brooks Todd
Published: September 2012

Finite difference methods can be a valuable and unexpected tool in acoustics education. As a wave acoustic simulation method, it provides instructive time-domain visualizations particularly useful for illustrating broadband wave effects like diffraction and interference. Furthermore, the knowledge required to implement these simulations can be taught in just a few hours of instruction with or without calculus in contrast to several other wave acoustic methods. The exposition provides opportunities for discussion of basic numerical methods as well as the physics of wave and diffusion processes. We present example projects from students of mixed science, engineering, and music backgrounds. After only four hours of instruction, they were able to independently simulate various room geometries with impedance boundary conditions along with a variety of other acoustical systems. Beyond strictly educational value, this is a flexible and free tool that the modern acoustician can use for research, physics-based simulation, or creation of broadband virtual sound fields.
Accuracy of acoustic simulations and the effects of material databases
Authors: Sauro Ronald
Published: September 2012

A discussion of the effects of material databases on the accuracy of predictions emanating from acoustic simulation programs. This brings to light the lack of inherent accuracy in these programs because of the lack of accuracy in the measurement of absorption, scattering and diffusion parameters. Some of the predictions can be shown to be off as much as 300 to 500 per cent. We look at possible corrections in these measurements and how they can improve these predictions.
Estimating numerical density of scatterers in monotype aggregations using the statistics of broadband echoes: Applications to fish echoes
Authors: Lee Wu-Jung , Stanton Timothy K. , Lavery Andone C.
Published: September 2012

The statistics of echoes from active sonar systems can yield important information on aggregations of scatterers. This study explores the use of echo statistics for estimating the numerical density of scatterers in monotype aggregations. Here, “monotype” refers to scatterers with the same scattering amplitude distribution in the considered frequency range. The signals are broadband, and the geometry involves direct paths between the sonar and the scatterers without interference from boundaries. Model probability density functions (pdf's) of envelope amplitudes of matched-filter outputs are numerically generated by varying the number of Rayleigh scatterers randomly-distributed in a half-space shell while accounting for the frequency-dependent system response, scatterer response, and beampattern effects. The shape of the echo pdf as observed by the sonar receiver is highly non-Rayleigh when there are few scatterers in the beam, and gradually approaches the Rayleigh distribution when the number of scatterers increases. This model is applied to broadband fish echoes (30-70 kHz) collected in the ocean through a best-fit procedure. The inferred numerical density of fish is comparable to the density estimated using corresponding measurements of volume backscattering strength and modeled target strengths.
Acoustic characterization of thecosome pteropods and recent field measurements in the context of ocean acidification
Authors: Lavery Andone C. , Lawson Gareth L. , Wiebe Peter H. , Stanton Timothy K. , Fincke Jonathan R. , Copley Nancy J.
Published: September 2012

One of Clay’s passions was modeling the scattering physics of marine organisms, a passion that has transcended into new generations of scientists. The focus of this presentation is thecosome pteropods, a widely and patchily distributed group of shelled zooplankton that are important members of pelagic ecosystems as they constitute important prey for a variety of other zooplankton and top predators. Acoustic techniques are well suited to sampling pteropods on relevant spatial and temporal scales as they secrete aragonite shells that make them highly efficient scatterers of sound. However, pteropod shells are complex and very susceptible to an increasingly corrosive seawater environment due to ocean acidification. Understanding the scattering physics is key to using acoustics as a quantitative remote sensing tool. Here we report on recent field measurements that combine the use of broadband (30-600 kHz) and narrowband (43, 120, 200, and 420 kHz) acoustic scattering techniques, as well as supporting in situ measurements (nets, optics, CTD and ocean chemistry) to investigate the distribution, abundance and size of pteropods in both the northwest Atlantic and the northeast Pacific in relation to the oceanic chemistry. Existing scattering models are tested, and improvements and modifications to the acoustic instrumentation and models are suggested.
Echo statistics: Pursuing one of Clay's visions
Authors: Stanton Timothy K. , Chu Dezhang
Published: September 2012

One of the first papers that Clay gave to one of the authors (TKS) when he entered Clay's office in 1980 was one of Clay's papers involving echo statistics and, specifically, accounting for beampattern effects in using single beam echoes from resolved fish to estimate their target strength and abundance. That, and a multitude of conversations with Clay helped propel TKS, and later DC, into a career where echo statistics was an integral aspect of their work. We will review our work on echo statistics associated with a variety of scatterers--the seafloor, sea ice, fish, zooplankton, and machined objects. A key aspect of this work has been connecting the physics of the scattering process and sonar parameters with parameters of the statistical functions (such as shape parameter).
Broadband synthetic aperture chirp reflection profiling
Authors: Schock Steven , Sara Jason , Walsh Kenneth M.
Published: September 2012

A newly developed towed chirp subbottom profiler transmits FM pulses with a bandwidth of three octaves to generate high resolution reflection profiles of the seabed. The broad bandwidth of the pulses, generated with two arrays of piston sources, produces the temporal resolution needed for resolving fine sediment layering. A 40 channel horizontal hydrophone array, embedded in vehicle wings, provides the acoustic aperture for enhancing the across track resolution of subsurface features and reducing sediment scattering noise. After application of a matched filter, synthetic aperture processing of hydrophone data generates a large aperture along the track of the sonar vehicle thereby improving along track image resolution and obtaining a further reduction in scattering noise. The reductions in backscattering from sediments yield imagery with improved subsurface penetration. The reflection profiles are stacked envelopes of coherently summed data formed by time domain focusing on planar surfaces oriented over a range of discrete slopes. This work was funded by the National Science Foundation.
Odontocete biosonar signals: Functional anatomy or signal design
Authors: Au Whitlow W.
Published: September 2012

There are between 67 and 76 species of odontocetes (toothed whales) and presumably all have biosonar capabilites. There are three fundamental biosonar signal types that can be categorized by types of marine mammals that produce these signals. Whales and dolphins that can emit whistle signals (except for sperm whales) project short broadband clicks containing about 5 to 7 cycles with decaying exponential envelope and Q (center frequency over bandwidth) between 2 and 3. Porpoises do not whistle and produce polycyclic narrow band high frequency biosonar signals with approximately 20 or more cycles with a modified sinusoidal amplitude envelope and Q around 14. Biosonar waveforms of beaked whales (also non-whistling animals) typically have 10-15 cycles with a linear FM component and Q around 4. This presentation will discuss the characteristics of the three different biosonar signal types and suggest some motivation factors involved with the use of the different signals. The type of prey and their habitat will also be included in the discussion. It will be shown that in some cases, the signal type is motivated by anatomical constraints of the odontocete and in other cases, the backscatter characteristics of the prey may be the most important factor.
Measuring the covertness of broadband sonar waveforms
Authors: Park Joonho D. , Doherty John F.
Published: September 2012

In underwater environment, the platform uses active sonar to estimate the range to the target, covertly. The target employs detectors designed to find anomalies in its ambient environment, including man-made waveforms such as ones transmitted by the platform. However, the structure of the waveform is unknown. In this scenario, we try to measure the covertness of the waveforms transmitted by the platform in various scenarios using a quantity related to relative entropy, and the performance of range estimation using the covert waveform. At the target, we measure the maximum probability of detection of the sonar waveform, for a specified false alarm rate. At the platform, we measure the probability of estimating the range to the target correctly. The performances of both processes are dependent on the amount of information one has about the ambient environment, the structure of the transmitted waveform, and the actual range between the platform and the target. We show how the performances are dependent on the accuracy of the knowledge about these elements.
Considerations in designing piezocomposite transducers and arrays for broadband sonar systems
Authors: Doust Barry , Mudarri Tim , Ursch Connie , Aghia Joe , Pazol Brian
Published: September 2012

The term broadband is commonly used to refer to the capability of a sonar system. Recent advances in signal processing and system electronics have re-defined capabilities for these systems and introduced new complex broadband pulse requirements for the sonar transducer. Advances in 1-3 piezocomposite technology have addressed this need through optimization of materials and innovative electroacoustic designs to provide high performance broadband solutions. Taking full advantage of this transducer technology requires careful consideration of the total system performance including dynamic range of receiver electronics, available transmit voltage/current/power, directivity and array configuration. This generalized study considers the design options available for optimizing transducers and arrays for broadband operation. Several Langevin or sandwich style Piezocomposite transducer configurations will be presented for both monostatic (two-way) and bistatic (separate receive and transmit) transducer systems and the trades in terms of total system performance. The study includes comparison of design optimization methodologies based on peak frequency response, impedance phase center or maximum transmit power factor, and combined two way system response. Emphasis will be on conventional piezoceramic materials with some discussion of second generation single crystal materials and their potential in future systems.
Multiple-timbre fundamental frequency tracking using an instrument spectrum library
Authors: Bay Mert , Beauchamp James W.
Published: September 2012

Recently many researchers have attempted automatic pitch estimation of polyphonic music (e.g., Li et al., IEEE Trans ASLP, 2009). Most of these attempts have concerned themselves with the estimation of individual pitches (F0s) while not associating the estimated pitches with the particular instruments that produce them. Estimating pitches for each instrument will lead to full music transcription. Individual instrument F0 tracks can be used in music information retrieval systems to better organize and search music. We propose a method to estimate the F0 tracks for a set of harmonic instruments in a sound mixture, using probabilistic latent component analysis (PLCA) and collections of basis spectra indexed by F0 and instrument learned in advance. The PLCA model is extended hierarchically to explain the observed input mixture spectra as a sum of basis spectra from note(s) of various instruments. The polyphonic pitch tracking problem is posed as inferring the most likely combination of the active note(s) from different instruments. Continuity and sparsity constraints are enforced to better model how the music is produced. The method was trained on a common instrument spectrum library an evaluated using an established polyphonic audio dataset.
Absolute pitch is associated with a large auditory digit span: A clue to its genesis
Authors: Deutsch Diana , Dooley Kevin
Published: September 2012

Absolute pitch (AP) is very rare in North America and Europe, and its genesis is unclear. Its prevalence is far higher among tone language speakers, and among those with early onset of musical training. However, most nontone language speakers with early and extensive musical training do not possess AP. To test the hypothesis that an unusually large auditory memory is involved in the genesis of AP, at least in nontone language speakers, we recruited 7 AP possessors, and 20 AP nonpossessors. All subjects were primary speakers of English, had begun musical training at ≤ age 6, and were UCSD students or recent graduates. The two groups were matched for age and years of musical experience. All subjects were administered an auditory digit span test, followed by a visual digit span test, with digits presented 1/sec. While the average auditory digit span was 8.1 digits for the AP nonpossessors, it was 10.0 digits for the AP possessors. This difference between the two groups was highly significant (p = 0.0015, 1-tailed). The AP possessors also marginally outperformed the nonpossessors on the visual digit span test; however this difference was nonsignificant. These new findings provide a clue to a genetic component of AP.
Measurement and analysis of timing asynchronies in ensemble performance
Authors: Ren Gang , Roessner Stephen , Hosakere Shivaswamy Samarth , Headlam Dave , Bocko Mark
Published: September 2012

Timing asynchrony is an important timing descriptor of ensemble music performance. In this paper the timing asynchrony is measured as offsets between “concurring” music onsets. Specifically we measure the offset between music note onsets that are prescribed to be synchronized according to the music score. First, we conduct measurements on the multi-track audio with separate instrument tracks. These multi-track materials are recorded by using acoustically isolated recording booth or by conducting multiple recording rounds. We then perform statistical analysis both on individual asynchrony points and on asynchrony points at key coordination locations, such as the start and the end of a music phrase. We emphasize in the analysis that the musical timing asynchronies should not be treated only as performance discrepancies because part of these micro-deviation patterns provide artistic “lively” elements. We also generalize the proposed framework to mixed-down polyphonic recordings. For polyphonic recordings where clear onsets can be identified we perform similar measurement and analysis algorithms as for separated multi-track recordings. For mixed-down polyphonic recordings where a clear separation of instrument tracks is not possible, we use onset dispersions, which measure the offset range of sonic partials onsets in an coordination points, as an alternative timing asynchrony descriptor.
The implementation of pyschoacoustical signal parameters in the wavelet domain
Authors: Borland Matt , Birkett Stephen
Published: September 2012

Introducing Wavelet techniques into the psychoacoustical analysis of sound signals provides a powerful alternative to standard Fourier methods. In this paper the reformulation of existing psychoacoustical signal parameters using wavelet methods will be explored. A major motivation for this work is that traditional psychoacoustical signal analysis relies heavily on the Fourier transform to provide a frequency content representation of a time signal, but this frequency domain representation is not always accurate; especially for sounds with impactive components. These impactive events can have a more significant contribution to the calculation of psychoacoustical signal parameters by reformulating existing psychoacoustic parameters in the Wavelet domain that are dependent on the Fourier transform. To provide concrete examples of the results simulated “plucked string” sounds are analyzed with analogous Fourier and Wavelet domain signal parameters to demonstrate the difference in performance achieved using Wavelet methods for sounds which have impactive components.
Micro-perforated elements in complex vibro-acoustic environment: Modelling and applications
Authors: Yu Xiang , Maxit Laurent , Guyader Jean-Louis , Cheng Li
Published: September 2012

Micro-perforated structures/panels (MPP) are widely used in various architectural, industrial and environmental applications for providing efficient sound absorptions. More recently, they found their use in compact mechanical systems, in which the property of the MPP is shown to be strongly influenced by the surrounding vibro-acoustic environment, which is drastically different from the one dimensional Kundt tube configuration, usually used in existing works. Unfortunately, very little has been done in this regard, due to the fact that modeling such a vibro-coustic system with MPPs as integrative elements is a very challenging task, not even to mention the optimization. Recently, a vibro-acoustic formulation based on the Patch Transfer Function (PTF) approach was proposed to model micro-perforated structures in a complex vibro-acoustic environment. As a sub-structuring approach, PTF allows assembling different vibro-acoustic subsystems, including micro-perforations and the flexibility of a MPP, through coupled surfaces. The proposed formulation provides explicit representation of the coupling among subsystems, with enhanced capability of handling system complexities and facilitating system optimization. In this talk, the overall approach will be reviewed and applied to a number of typical examples. The versatility and efficiency of the method as well as the underlying physics are demonstrated.
Hybrid silencer by using micro-perforated plate with side-branch cavities
Authors: Wang Xiaonan , Choy Yatsze , Cheng Li
Published: September 2012

A plate silencer consists of an expansion chamber with two side-branch cavities covered by light but extremely stiff plates. It works effectively with wide stopband from low-to-medium frequencies only if the plate is extremely stiff, to ensure a strong reflection of acoustic wave to the upstream in the duct. However, a plate with slightly weak bending stiffness will result in non-uniform transmission loss (TL) spectra with narrowed stopband. In this study, a hybrid silencer is proposed by introducing micro-perforations into the plate to elicit the sound absorption in order to compensate for the deficiency in the passband caused by the insufficient sound reflection in certain frequency range due to plate with weaker stiffness. A theoretical model, capable of dealing with the strong coupling between the vibrating micro-perforated plate and sound fields inside the cavity and the duct, is developed. Through a proper balancing between the sound absorption and reflection, the proposed hybrid plate silencer with moderately stiff plates is shown to outperform the typical plate silencer with very stiff plate. Whilst releasing the harsh requirement on the bending stiffness of the plate, the proposed hybrid silencer provides a more flattened and uniform TL and a widened stopband by about 30%.