bluuebunny/crossref_metadata_2025 huggingface dataset:
Left Atrial Volume Best Predicts Recurrence after Catheter Ablation in Patients with Persistent and Longstanding Persistent Atrial Fibrillation
Authors: KOHÁRI MÁRIA , ZADO ERICA , MARCHLINSKI FRANCIS E. , CALLANS DAVID J. , HAN YUCHI
Published: October 2013

Introduction

Patients with persistent and longstanding persistent atrial fibrillation (AF) have a higher recurrence rate after antral pulmonary vein isolation (PVI). We sought to determine the clinical, invasive, and noninvasive diastolic function parameters that are associated with AF recurrence after ablation in patients with persistent and longstanding persistent nonvalvular AF.

Methods and Results

We studied 125 consecutive patients with persistent and longstanding persistent AF who underwent antral PVI at our institution between April 2009 and April 2011. Standard clinical parameters, left atrial (LA) pressure measured at transseptal puncture, and standard diastolic function parameters on transthoracic echocardiographic (TTE) parameters were assessed. TTE was performed in sinus rhythm the first day following radiofrequency catheter ablation. Ablation eliminated AF in 83 of 125 (66.4%) patients (mean age 61.3 ± 8.9, 81% male) during 17.8 ± 7.7 months of follow‐up. Using logistic regression analysis, AF duration prior to ablation (P = 0.04, odds ratio [OR]: 1.03, 95% confidence interval [CI] 1.0–1.06) was found to be the only clinical parameter significantly associated with AF recurrence. According to multiple logistic regression analysis, the indexed LA minimum volume of 26 cm3/m2 (P = 0.009, OR: 4.9 95% CI 1.5–16.2) was the only independent imaging parameter associated with AF recurrence.

Conclusion

Indexed minimal LA volume is highly associated with ablation success in patients with persistent and longstanding persistent AF.
Three‐Dimensional Echocardiographic Optimization Improves Outcome in Cardiac Resynchronization Therapy Compared to ECG Optimization: A Randomized Comparison
Authors: SONNE CAROLIN , BOTT‐FLUGEL LORENZ , HAUCK SIMON , HADAMITZKY MARTIN , LESEVIC HASEMA , DEMETZ GABRIELE , BRAUN DANIEL , WOLF PETRA , HAUSLEITER JÖRG , SCHÖMIG ALBERT , KOLB CHRISTOF
Published: October 2013

Aims

There is little consensus on optimal atrioventricular (AV) and ventricular‐to‐ventricular (VV) intervals in cardiac resynchronization therapy (CRT). The aim of this study was to examine a novel combination of Doppler echocardiography (DE) and three‐dimensional echocardiography (3DE) for individualized AV‐ and VV‐interval optimization compared to conventional electrocardiogram (ECG) optimization.

Methods

In this double‐blind, randomized controlled trial, 77 patients (male: 57, age: 68 ± 10 years) with severely reduced ejection fraction (EF), New York Heart Association (NYHA) class III or IV, and wide QRS complex (>120 ms) have been included. Patients were randomized to either AV‐ and VV‐interval optimization using DE and 3DE (group 1, n = 39) or ECG (group 2, n = 38). 3DE was performed in all patients for the evaluation of left ventricular (LV) dimensions, EF and systolic dyssynchrony index (SDI), and NYHA class obtained before CRT and after 3 months. Primary endpoint of the study was clinical response to CRT, defined as a reduction of NYHA class by ≥1 score. Secondary endpoints were change of EF, LV volumes, and SDI.

Results

There were significantly more responders in group 1 (82%) than in group 2 (58%, P = 0.021). Similarly, group 1 showed a larger increase in EF (7.0 ± 6.0% vs 3.4 ± 5.6%, P = 0.015) and a more pronounced reduction of SDI (–4.5 ± 5.9% vs –1.5 ± 5.6%, P = 0.039) than group 2.

Conclusion

Compared with conventional ECG optimization, this novel echocardiographic optimization protocol resulted in a significantly higher response rate, improved LV systolic function, and may be used to select the optimal AV and VV intervals in CRT.
Percutaneous Axillary Vein Approach in Pediatric Pacing: Comparison with Subclavian Vein Approach
Authors: SILVETTI MASSIMO STEFANO , PLACIDI SILVIA , PALMIERI ROSALINDA , RIGHI DANIELA , RAVÀ LUCILLA , DRAGO FABRIZIO
Published: October 2013

Aims

The subclavian vein approach has been used for 20 years in our center for pacemaker (PM) implantation in children, but it carries risks of hemothorax/pneumothorax and lead fracture, which could be reduced by axillary vein approach.

Methods and Results

This is a prospective study enrolling the first 48 consecutive pediatric patients (age: 12.3 ± 4.6 years) who underwent PM/implantable cardioverter‐defibrillator leads implantation through axillary vein (guided by contrast venography) between 2009 and 2012 (group I). A comparison was made with the outcomes of the subclavian vein approach (group II) in 41 patients, age 12.3 ± 4.8 years, consecutively enrolled between 2006 and 2011. The two groups showed no significant differences for the variables examined except for follow‐up, longer in group II, and for alternative ventricular pacing sites, more frequent in group I. Axillary vein diameter was 7.9 ± 1.7 mm and showed positive correlation with height (r = 0.77). The axillary vein approach was effective in 93.7% of patients. The unsuccessful procedures occurred in patients with significantly lower age and smaller venous diameters. The subclavian vein approach was effective in 100% of patients. Sixty‐two leads were implanted in group I, 54 in group II. There were neither intraoperative complications in both the groups, nor significant differences for early and late complications.

Conclusions

The axillary vein approach for PM implantation in children is effective and safe for physicians skilled with subclavian vein approach. Younger patients with smaller vein diameters are at low risk for unsuccessful procedure.
Formation and Direct Repair of UV‐induced Dimeric DNA Pyrimidine Lesions
Authors: Kneuttinger Andrea Christa , Kashiwazaki Gengo , Prill Stefan , Heil Korbinian , Müller Markus , Carell Thomas
Published: October 2013

Direct repair of UV‐induced DNA lesions represents an elegant method for many organisms to deal with these highly mutagenic and cytotoxic compounds. Although the participating proteins are structurally well investigated, the exact repair mechanism of the photolyase enzymes remains a vivid subject of current research. In this review, we summarize and highlight the recent contributions to this exciting field.
Marching to Different Drummers? The Performance Effects of Alignment between Political and Managerial Perceptions of Performance Management
Authors: Walker Richard M. , Jung Chan Su , Boyne George A.
Published: October 2013

The relationship between politicians and bureaucrats is central to the administration of modern democratic societies, yet it often is neglected in studies of the performance of public organizations. In this article, the authors examine the performance effects of alignment between politicians’ and senior managers’ perceptions of one of the more pervasive public management reforms over recent decades: performance management. Evidence from a panel of English local governments supports the hypothesis that alignment of views between politicians and senior managers on performance management is associated with better organizational performance. Furthermore, this relationship is strengthened in organizations that display higher levels of role flexibility by managers and greater trust between politicians and managers.
Opportunities and Challenges for Public Libraries to Enhance Community Resilience
Authors: Veil Shari R. , Bishop Bradley Wade
Published: October 2013

This study bridges a gap between public library and emergency management policy versus practice by examining the role of public libraries in the community resource network for disaster recovery. Specifically, this study identifies the opportunities and challenges for public libraries to fulfill their role as a FEMA‐designated essential community organization and enhance community resilience. The results indicate there are several opportunities for libraries to enhance community resilience by offering technology resources and assistance; providing office, meeting, and community living room space; serving as the last redundant communication channel and a repository for community information and disaster narratives; and adapting or expanding services already offered to meet the changing needs of the community. However, libraries also face challenges in enhancing community resilience, including the temptation to overcommit library capacity and staff capability beyond the library mission and a lack of long‐term disaster plans and collaboration with emergency managers and government officials. Implications for library and emergency management practice and crisis research are discussed.
A teacher‐centered exploration of the relevance of social factors to theory of mind development
Authors: Wright Barlow C. , Mahfoud Janina
Published: October 2013

Many accounts of children's Theory of Mind (ToM) development favor a cognitive explanation, for example, in terms of mental representational improvements at or before 4 years. Here, we investigated whether social factors as rated by a child's teacher, are related to ToM development. We tested 82 children of 3–6 years on each of four ToM tasks, and their class teacher completed a social questionnaire about each child's playing behavior, sharing, talkativeness, confidence, aggressiveness and outgoingness. A measure of task memory and the child's gender were also recorded. Here, children generally passed ToM tasks after 5 years‐old, but no one gender performed reliably better than the other. Teacher‐rated confidence and playing behavior were correlated to ToM. But in a regression analysis, these were replaced by teacher‐rated talkativeness; with age and memory given primacy in both sets of analyses. It is concluded that maturation and cognitive factors may well have primacy but social factors, facilitated during early primary education, must also be given a role in ToM development.
The relevance of security: A latent domain of attachment relationships
Authors: Mannarini Stefania , Boffo Marilisa
Published: October 2013

In the present study an adult attachment dimension, latent to the constructs of security, anxiety, and avoidance, was hypothesized, wherein security was expected to occupy the most relevant position. Furthermore, the reciprocal functioning of attachment constructs and their interactions with self‐esteem were explored. Four hundreds and thirty‐four Italian university students responded to two adult attachment questionnaires (Attachment Style Questionnaire and Adult Attachment Questionnaire) and to the Rosenberg Self‐esteem scale. A Many‐Facet Rasch Measurement modeling approach was adopted. The main results can be summarized as follows: (a) security, anxiety, and avoidance are nested under one latent attachment dimension; (b) security occupies the most prominent position on the dimension; (c) security is positively associated with a moderate level of attachment anxiety and negatively related to avoidance; and (d) a positive interaction between self‐esteem and security, and a negative relation between self‐esteem and anxiety, were detected. Theoretical, clinical, and empirical implications of the results are further discussed.
50th Anniversary Article: Effect of Sensor Noise on the Resolution and Spatial Resolution of Displacement and Strain Maps Estimated with the Grid Method
Authors: Grediac M. , Sur F.
Published: October 2013

This paper deals with noise propagation from camera sensor to displacement and strain maps when the grid method is employed to estimate these quantities. It is shown that closed‐form equations can be employed to predict the link between metrological characteristics such as resolution and spatial resolution in displacement and strain maps on the one hand and various quantities characterising grid images such as brightness, contrast and standard deviation of noise on the other hand. Various numerical simulations confirm first the relevance of this approach in the case of an idealised camera sensor impaired by a homoscedastic Gaussian white noise. Actual CCD or CMOS sensors exhibit, however, a heteroscedastic noise. A pre‐processing step is therefore proposed to first stabilise noise variance prior to employing the predictive equations, which provide the resolution in strain and displacement maps due to sensor noise. This step is based on both a modelling of sensor noise and the use of the generalised Anscombe transform to stabilise noise variance. Applying this procedure in the case of a translation test confirms that it is possible to model correctly noise propagation from sensor to displacement and strain maps, and thus also to predict the actual link between resolution, spatial resolution and standard deviation of noise in grid images.
‘Trusting the numbers’: mineral prospecting, raising finance and the governance of knowledge
Authors: Majury Niall
Published: October 2013

Mineral prospecting and raising finance for ‘junior’ mining firms has historically been regarded as a speculative activity. For the regulators of securities markets upon which ‘junior’ mining companies seek to raise capital, a perennial problem has been handling not only the indeterminacy of scientific claims, but also the social basis of epistemic practices. This paper examines the production of a system of public warrant and associated knowledge practices intended to enable investors to differentiate between ‘destructive’ and ‘productive’ varieties of financial speculation. It traces the use of the notion of ‘disclosure’ in constructing and legitimising the ‘juniors’ market in Canada. It argues that though the work of ‘economics’ may be necessary in the construction of markets, it is by no means sufficient. Attention must also be given to the ways in which legal models of ‘the free‐market’ can be translated and constantly re‐worked across the sites and spaces of regulatory practice, animating the geographies of markets.
Red cell storage in E‐Sol 5 and Adsol additive solutions: paired comparison using mixed and non‐mixed study designs
Authors: Radwanski K. , Thill M. , Min K.
Published: October 2013

Background and Objectives

If transfusion of older stored red cells is found to negatively affect clinical outcome, one possible alternative to shortened outdate is the use of new additive solutions (AS) that ameliorate the storage lesion. Erythro‐Sol (E‐Sol), a previously developed next‐generation AS, has been reformulated into E‐Sol 5, which is compatible with current anticoagulants and AS volumes. The effect of E‐Sol 5 on red cells during storage compared to current AS has not been reported.

Materials and Methods

Paired, ABO‐matched whole‐blood units were collected into CPD anticoagulant, pooled, split and processed into plasma and red cell units with either 110 ml of Adsol or 105 ml of E‐Sol 5 within 8 h of collection. In Study 1, paired units in E‐Sol 5 and Adsol were sampled on Day 0 and every 7 days up to Day 42 (n = 10). In Study 2, paired units in E‐Sol 5 and Adsol were sampled only on Day 0 and Day 42 (n = 10).

Results

In Study 1, 2,3 DPG levels were maintained until Day 28 in E‐Sol 5 units and Day 14 in Adsol units. ATP levels were higher in E‐Sol 5 units until Day 21, after which they were comparable between the two groups. In both studies, metabolic activity was greater in E‐Sol 5 units with respect to glucose consumption and lactate production. Morphology scores were higher, and haemolysis and microparticles generated were lower in E‐Sol 5 vs. Adsol units. Weekly mixing of units lowered haemolysis and microparticle levels and increased potassium content on Day 42 in both additive solutions.

Conclusion

Regardless of whether units are mixed weekly or are stored non‐mixed, E‐Sol 5 slows the progression of the red cell storage lesion and improves the overall in vitro quality of RBC throughout storage.
Energy-Efficient Cooling of Liquid-Cooled Electronics Having Temperature-Dependent Leakage
Authors: Hall Shawn A. , Kopcsay Gerard V.
Published: October 2013

Energy conservation in data centers with liquid-cooled electronics is considered, taking into account the combined power consumption of both the electronics and the associated cooling equipment, particularly chillers. The energy-saving technique called “free cooling,” which is most effective at minimizing or eliminating the need for chillers when the temperature of the coolant delivered to the electronics is high, is shown to be at odds with the electronics itself, because of subthreshold leakage in complementary metal-oxide semiconductor (CMOS) transistors, which is minimized when coolant temperature is low. A mathematical model is developed to investigate this trade-off, to discover what liquid-coolant temperature is optimal overall, and thereby to determine what combination of free cooling and traditional chiller cooling should be used for minimal overall power consumption. As an example of how to apply the mathematical model, parameters are chosen in accordance with experimental measurements on an early prototype of a state-of-the-art, water-cooled computer (International Business Machines's (IBM) BlueGene/Q). Results for total data-center power (computer + cooling equipment) are obtained as a function of coolant temperature, the computational state of the computer (which affects CMOS leakage), and weather (which affects the ability to employ free cooling). For the type of system considered, the optimal coolant temperature is found to be a discontinuous function of the other parameters, and traditional chiller cooling is found sometimes to be more energy efficient than free cooling.
Numerical Prediction of Turbulent Flow and Heat Transfer Enhancement in a Square Passage With Various Truncated Ribs on One Wall
Authors: Xie Gongnan , Liu Jian , Zhang Weihong , Lorenzini Giulio , Biserni Cesare
Published: October 2013

Repeated ribs are often employed in the midsection of internal cooling passages of turbine blades to augment the heat transfer by air flowing through the internal ribbed passages. Though the research of flow structure and augmented heat transfer inside various ribbed passages has been well conducted, previous works mostly paid much attention to the influence of rib topology (height-to-pitch, blockage ratio, skew angle, rib shape). The possible problem involved in the usage of ribs (especially with larger blockage ratios) is pressure loss penalty. Thus, in this case, the design of truncated ribs whose length is less than the passage width might fit the specific cooling requirements when pressure loss is critically considered. A numerical study of truncated ribs on turbulent flow and heat transfer inside a passage of a gas turbine blade is performed when the inlet Reynolds number ranges from 8000 to 24,000. Different truncation ratio (truncated-length to passage-width) rib geometries are designed and then the effect of truncation ratio on the pressure drop and heat transfer enhancement is observed under the condition of constant total length. The overall performance characteristics of various truncated rib passages are also compared. It is found that the heated face with a rib that is truncated 12% in length in the center (case A) has the highest heat transfer coefficient, while the heated face with a rib that is truncated 4% at three locations over its length, in the center and two sides (case D), has a reduced pressure loss compared with passages of other designs and provides the lowest friction factors. Although case A shows larger heat transfer augmentation, case D can be promisingly used to augment side-wall heat transfer when the pressure loss is considered and the Reynolds number is relatively large.
Separate modal analysis for tumor detection with a digital image elasto tomography (DIET) breast cancer screening system
Authors: Kashif Amer S. , Lotz Thomas F. , Heeren Adrianus M. W. , Chase James G.
Published: October 2013

Purpose:

It is estimated that every year, 1 × 106 women are diagnosed with breast cancer, and more than 410 000 die annually worldwide. Digital Image Elasto Tomography (DIET) is a new noninvasive breast cancer screening modality that induces mechanical vibrations in the breast and images its surface motion with digital cameras to detect changes in stiffness. This research develops a new automated approach for diagnosing breast cancer using DIET based on a modal analysis model.

Methods:

The first and second natural frequency of silicone phantom breasts is analyzed. Separate modal analysis is performed for each region of the phantom to estimate the modal parameters using imaged motion data over several input frequencies. Statistical methods are used to assess the likelihood of a frequency shift, which can indicate tumor location. Phantoms with 5, 10, and 20 mm stiff inclusions are tested, as well as a homogeneous (healthy) phantom. Inclusions are located at four locations with different depth.

Results:

The second natural frequency proves to be a reliable metric with the potential to clearly distinguish lesion like inclusions of different stiffness, as well as providing an approximate location for the tumor like inclusions. The 10 and 20 mm inclusions are always detected regardless of depth. The 5 mm inclusions are only detected near the surface. The homogeneous phantom always yields a negative result, as expected.

Conclusions:

Detection is based on a statistical likelihood analysis to determine the presence of significantly different frequency response over the phantom, which is a novel approach to this problem. The overall results show promise and justify proof of concept trials with human subjects.
Evolution of mammalian hearing
Authors: Heffner Henry E. , Heffner Rickye S.
Published: October 2013

The comparative study of mammals reveals systematic differences in their hearing abilities. First, the ability to hear above 10 kHz (which apparently evolved for using pinna cues to localize sound) varies inversely with the size of an animal’s head such that smaller animals usually have better high-frequency hearing than larger ones. Second, low-frequency hearing ability is bimodally distributed: Although most mammals can hear below 125 Hz, about one third do not hear much below 500 Hz and probably do not use temporal coding for pitch perception. Third, sound localization acuity varies directly with the width of the field of best vision, indicating that a major source of evolutionary pressure on hearing is to direct the eyes to the source of a sound. Finally, while some mammals do not use the binaural time-difference locus cue and a few others do not use the binaural intensity difference cue, it is likely that all mammals that possess pinnae use pinna locus cues to localize sound. Taken together, these findings suggest that some of the hearing abilities of extinct mammals may be inferred from fossil evidence bearing on their head size, eyes, and the presence of pinnae.
Ambient noise inverted sonar performance sensitivity due to ocean variability
Authors: Arvelo Juan , Rouseff Daniel , Tang Dajun
Published: October 2013

Undersea noise was collected on a vertical array affected by ocean currents and internal waves. Such fluctuations are known to negatively affect the accuracy of the inferred bottom loss over grazing angles [Arvelo and Prosperetti, J. Acoust. Soc. Am. 120, 3257 (2006)]. However, bottom loss is just an intermediate parameter to sonar performance predictions. The bottom loss at the dominant incident angles on the ocean floor is of most importance to the prediction of sound transmission. Therefore, the focus of attention should be on the effect of waveguide dynamics on the predicted acoustic propagation using the estimated bottom loss. Simultaneous transmission loss measurements are compared against predictions from several snapshots of collected element-level wind-driven noise to determine the bias and statistical moments associated with the in situ sonar performance estimations across frequency and range. In addition, dominant mode rejection will be applied on a subset of the data that is influenced by nearby ship interference to examine its impact on the robustness of this approach to passive environmental assessment. [This effort was conducted under the auspices of the JHU/APL independent research and development program.]
Changes in host plant use favor divergence of vibrational signals in treehoppers (Membracidae: Enchenopa binotata)
Authors: McNett Gabriel D. , Cocroft Reginald B.
Published: October 2013

Shifts to novel host plants can have dramatic consequences for a wide range of traits in plant-feeding insects. If the traits affected are mating signals, host shifts can provide a direct source of reproductive isolation. Mating signal evolution will be affected when changes in host use, either by use of a different plant species or plant part, lead to communication in a different signal environment. The sensory drive hypothesis predicts that signals should adapt to transmit efficiently in their local environment. Signal divergence, therefore, can occur where closely related insect species occur on host plants with different signal transmission properties. These predictions were tested in two closely related species in the Enchenopa binotata species complex (Hemiptera: Membracidae), host-specific plant-feeding insects that communicate using plant-borne vibrations. Their mating signals are relatively pure tones that vary among species in frequency (pitch), the most important signal trait for mate recognition. As predicted by sensory drive, it is shown that two closely related E. binotata species have evolved signals that transmit most efficiently in their contrasting communication environments. Changes in host use thus favor divergence of the signal trait most important for behavioral isolation. [Work supported by NSF.]
Vibrational information in two life stages of the red-eyed treefrog: Agonistic communication signals and predation risk cues in an arboreal environment
Authors: Caldwell Michael S. , Warkentin Karen M. , McDaniel J. Gregory
Published: October 2013

Red-eyed treefrogs form dense mating aggregations and lay eggs in vegetation over neotropical ponds. Seismic information serves two important behavioral roles for this species. Adult males communicate with seismic signals during agonistic interactions, and embryos detect predators using vibrational cues. Males defending calling sites rapidly extend and contract their hindlimbs, shaking their bodies and the plant in tremulatory displays. This generates strong stereotyped substrate vibrations (12±0.4 Hz, constant amplitude) that propagate to other males. Temporal, amplitude, and frequency properties of this signal are all distinct from common background vibrations and, in videotaped interactions, tremulation vibrations appear behaviorally relevant. In contrast, embryos experience predator and benign-source vibrations that overlap in temporal, amplitude, and frequency properties. These vibrations first pass through the gelatinous egg clutch and are shaped by its physical properties. Modal analysis indicates that natural free vibration frequencies of clutches are low (fundamental: 17±2 Hz); these dominate both benign and dangerous direct disturbances. Additionally, the clutch acts as a frequency filter, rapidly attenuating energy over 200 Hz. Comparing the red-eyed treefrogs use of seismic information in communication and predator detection reveals the different requirements for perceptual strategies employing stereotyped and non-stereotyped information, and furthers our understanding of the seismic modality.
Bubble proliferation in shock wave lithotripsy
Authors: Pishchalnikov Yuri A. , McAteer James A. , Bailey Michael R. , Williams James C. , Sapozhnikov Oleg A.
Published: October 2013

Stone breakage is less efficient when lithotripter shock waves (SWs) are delivered at 2 Hz compared to slower 0.5–1-Hz pulse repetition rates (PRFs). This correlates with increased number of transient cavitation bubbles observed along the SW path at fast PRF. The dynamics of this bubble proliferation throughout the bubble lifecycle is investigated in this report. Cavitation bubbles were studied in the free-field of a shock wave lithotripter using fine temporal and microscopic spatial resolution (high-speed camera Imacon-200). A typical cavitation bubble became visible (radius>10 μm) under the tensile phase of the lithotripter pulse, and at its first inertial collapse emitted a secondary SW and formed a micro-jet, which then could break up forming ∼25 micro-bubbles. Subsequent rebound and collapse of the parent bubble appeared to produce a further 40–120 daughter bubbles visible following the rebound. Preexisting bubbles hit by the lithotripter SW also formed micro-jets and broke up into micro-bubbles that grew and coalesced, producing irregular-shaped bubbles that, in turn, broke into micro-bubbles upon subsequent inertial collapse. A conventional NTSC-rate camcorder was used to track cavitation bubbles from pulse-to-pulse, showing that a single bubble can give rise to a cavitation cloud verifying high-speed video results. [Work supported by NIH-DK43881.]
Effect of intermittent applications of continuous ultrasound on the viability, proliferation, morphology and matrix production of chondrocytes in 3-D matrices
Authors: Turner Joseph A. , Noriega Sandra , Mammedov Tarlan , Subramanian Anu
Published: October 2013

Chondrocytes, the cellular component of articular cartilage, have long been recognized as strain-sensitive cells, have the ability to sense mechanical stimulation through surface receptors and intracellular signaling pathways. This response has been exploited to facilitate chondrocyte culture in in vitro systems such as those that use hydrostatic pressure, dynamic compression, hydrodynamic shear, as well as low-intensity pulsed ultrasound (US). While the ability of US to influence chondrogenesis has been documented, the precise mechanisms of US induced stimulation are unclear. Thus, a critical need remains to evaluate the impact of US on chondrocytes in 3-D cultures, a necessary microenvironment for maintaining chondrocyte phenotype. Here, chondrocytes seeded in 3-D scaffolds were subjected to continuous ultrasound stimulation at several frequencies for the same number of cycles, applied twice in a 24-hour period. Non-US stimulated scaffolds served as the control. Both groups were maintained in culture for 10 days and were assayed at the conclusion of the culture period (total DNA content, morphology, and cartilage specific gene expression). Our results show that chondrocytes stimulated with continuous US for predetermined time intervals possessed 1.2 to 1.4-times higher cellular viability than the control as well as higher levels of type-II collagen and aggrecan mRNA expression.
Effective medium model of human lung response to low-frequency sound
Authors: Wochner Mark S. , Ilinskii Yurii A. , Hamilton Mark F. , Zabolotskaya Evgenia A.
Published: October 2013

This presentation is an extension of work described previously [Ilinskii et al., J. Acoust. Soc. Am. 120, 3194 (2006)] on modeling the response of human lung to low-frequency underwater sound. A lumped element model with alveoli represented as truncated octahedra forming a periodic lattice with cubic symmetry was developed to capture the microscopic properties of collagen and elastin. The lattice is deformed quasistatically to determine the three elastic constants associated with the macroscopic behavior of the system. In reality lung tissue is likely isotropic and therefore a method of averaging is utilized to determine the two Lamé constants of the effective medium. The volume of the lung is varied to simulate tidal breathing. The Lamé constants are determined for the given lung volume and used in a commercial finite element package to calculate the amplitude of vibration due to low-frequency acoustic excitation. The resulting spectral response and scattered sound field are calculated for a water-loaded viscoelastic sphere composed of the effective lung medium. Increase in lung volume tends to decrease the resonance frequency, but increasing stiffness due to collagen tends to increase the resonance frequency. Competition of these effects is discussed. [Work supported by ONR and ARL IR&D.]
Application of the continuous wavelet transform to acoustic emissions generated by joint and muscle motion
Authors: Fischer Wayne , Guarino Joe
Published: October 2013

The subject matter of this presentation will refer to the preliminary development of a non-destructive and non-invasive diagnostic method using low-frequency acoustic emissions to characterize and diagnose joint and muscle disorders. Low-frequency acoustic emissions have had limited effectiveness when used in the past to characterize and diagnose joint and muscle disorders because Fourier transform techniques were not capable of describing when a specific frequency occurred during an acoustic emission event. With the development of techniques that decompose a signal into time-frequency representations using wavelet analysis it is now possible to describe complex transient signals. While the continuous wavelet transform (CWT) method has already made an impact within many areas of the medical sciences such as EEG analysis, ECG analysis, and DNA-sequence analysis, the method is now becoming popular for analyzing muscle and joint acoustic emissions from the hip, knee, and elbow joints. This paper will present the results of our application of the CWT to the analysis of acoustic emissions from the shoulder joint.
Clearance of harbor navigation channels with high-resolution bottom surveys at 10 knots
Authors: Glynn James , de Moustier Christian , Huff Lloyd
Published: October 2013

The safety of navigation channels leading to or within a harbor can be ensured by repeat high-resolution bottom surveys to detect new hazards or obstacles. This task requires a sonar system capable of acquiring high-resolution acoustic backscatter imagery and bathymetry. Because of the generally shallow water depths ( 20 m), survey efficiency dictates data collection over wide swaths at high speeds. We have demonstrated these capabilities in October 2006 in New York harbor, NY, with a Klein 5410 multibeam side-looking sonar system yiedling swath coverage of at least 7 times the water depth at a nominal survey speed of 10 knots. This has been achieved by integrating the hull-mounted sonar system with precision attitude ( 0.01 deg) and timing ( 10-6 s) references, and by designing and implementing a full vector processing algorithm to obtain co-registered high-resolution bathymetry and acoustic backscatter imagery, allowing us to resolve sub-meter targets. [Work funded by NOAA-NMFS].
Application of maximum length sequences to photoacoustic chemical analysis
Authors: Muehleisen Ralph T. , Soleimani Arash
Published: October 2013

There is a great need for inexpensive, rugged, portable, and versatile chemical detectors for use in both security and environmental measurement. Current sensors that meet the inexpensive, portable, and rugged criterion are usually limited in sensitivity and dedicated to detecting a limited number of chemicals. Sensors designed for airborne measurement typically cannot be used to measure surface chemicals. The photoacoustic method is one of the most sensitive techniques for trace analysis in both the air and on surfaces. Unfortunately, photoacoustic systems are typically expensive, usually not portable, and usually cannot be used for both airborne and surface chemical analysis. A new design for a photoacoustic measurement system is proposed that utilizes maximum length sequences (MLS) to modulate multiple, inexpensive, fixed frequency, laser diodes. The MLS modulation and post-acquisition correlation processing should provide a very high signal-to-noise measurement without need for lock-in amplifiers, high power pulsed lasers, optical modulators, or resonant measurement cells. These changes should allow for the design of a rugged, portable, inexpensive photoacoustic measurement system that can be used for both airborne and surface trace chemical detection.
Semi-occluded vocal tract postures and their application in the singing voice studio
Authors: Nix John P. , Simpson C. Blake
Published: October 2013

Many singing teachers employ semi-occluded vocal tract postures in their teaching. These postures can be divided into three types: (1) postures where the semi-occlusion remains consistent over time, as in singing vowels into a straw, the sustained phonation of voiced fricative consonants and the sustained phonation of nasal consonants; (2) postures where the occlusion is oscillatory, as in the lip buzz, the raspberry, and the rolled /r/; (3) postures where the semi-occlusion or occlusion is very transitory, as is found in the semi-vowels /j/ and /w/ and the voiced plosive consonants. The presentation will review the benefits of these semi-occluded postures, show videoendoscopic images of the pharynx and larynx and electroglottography of the vocal folds while the semi-occluded postures listed above are used as pilots to the vowels /i/, /u/, and /a/, and will demonstrate some of the traditional uses of the semi-occluded postures in singing pedagogy.
A real-time display system for singing voice development
Authors: Howard David M. , Daffern Helena , Brereton Jude , Welch Graham F , Himonides Evangelos , Howard Andrew W.
Published: October 2013

Central to any pedagogical nurturing of singing development is the provision of some form of meaningful feedback to the developing singer. Singing teachers draw on their personal experiences within an essentially oral culture where expertise is handed down from teacher to student generation by generation. The teacher is engaged in a psychological translation of the student’s performance, and a dual possibility thereby exists for the misinterpretation of information; the teacher may not describe the student’s performance appropriately and/or the student may not understand how to modify his or her singing behavior as intended. The provision of quantitative visual feedback provides a physical basis for vocal development. This paper will describe a real-time display system for singing training known as ‘‘WinSingad,’’ which enables acoustic and voice source aspects to be viewed in real-time on a PC. The system has been used in singing lessons and has been universally welcomed by students and teachers alike for its ease of use and display clarity. Specific aspects of voice development are now linked with particular displays and these will be explored in this presentation.
Elastic constants, Blackman diagrams, and new lanthanide–actinide insights
Authors: Ledbetter Hassel
Published: October 2013

Using monocrystal elastic constants and Blackman diagrams, one can infer material interconnections, physical-property trends, and knowledge about interatomic bonding. After reviewing briefly the f.c.c.-metal case, focus shifts to Ce, Pu, Th, with known monocrystal f.c.c. elastic constants, the Cij. For U and a few other lanthanide-actinide cases, one can deduce the f.c.c. Cij. From these results, for the lanthanides-actinides, there follow several conclusions: (1) elastic anisotropy ranges widely; (2) Poisson ratios are low; (3) interatomic bonding varies widely; (4) against other f.c.c. metals, all show unusual negative Cauchy pressures (three-body forces); (5) a strong covalent-bonding component occurs, perhaps related to localized (or semilocalized) f-electrons; (6) delta-Pu behaves most oddly; (7) delta-Pu may share some bonding features with f.c.c. alkali metals. [Work supported by DoE, NSF, State of Florida.]
Temporal relationship between speech auditory brainstem responses and phonemes envelopes
Authors: Akhoun Idrick , Gallego Stephane , Veuillet Evelyne , Collet Lionel
Published: October 2013

Auditory brainstem responses evoked by synthetic phonemes (speech-ABR) were recorded on normal hearing subjects stimulated monaurally on the right ear at 60 dB sensation level. The speech-ABR consists of an onset response (OR) followed by the frequency following response (FFR), which results of the summation of phase locking underlying activities in the auditory cells of the brainstem nuclei. The FFR mimicked accurately the envelope of the stimulus, defined as the absolute value of the stimulus filtered at the cutoff frequency of the speech ABR spectrum. However, the FFR was more shifted relative to the vowel than the OR did relative to the onset of the stimulus, which is close to the cochlear delay usually reported. Little interindividual discrepancies were found. Delay values give information about the sites of generation of the speech-ABR. This method may help to objectivate the temporal encoding of phonemes in the brainstem. Hence the potential assessing of speech intelligibility, as temporal speech envelopes retain perfect intelligibility [R. Drullman, J. Acoust. Soc. Am. 98, 1796–1798 (1995)]. [Work supported by CNRS.]
The effect of fundamental frequency in simulated electric-acoustic hearing
Authors: Brown Christopher A. , Bacon Sid P.
Published: October 2013

Individuals with residual hearing restricted to low frequencies are candidates for electric-acoustic stimulation (EAS). When low-frequency acoustic information is added to either real or simulated high-frequency electric stimulation, speech recognition often improves dramatically. This may reflect the availability of fundamental frequency (f0) information in the acoustic region. We tested this directly. In particular, we examined the relative contributions of f0 and the amplitude envelope of speech by replacing the low-frequency speech with a tone that was modulated either in frequency to track the f0 of the speech, in amplitude with the extracted envelope of the low-frequency speech, or both. A female talker was combined with various backgrounds and processed with a four-channel vocoder to simulate electric hearing. Across all backgrounds, intelligibility improved significantly when a tone tracking f0 was added to vocoder stimulation and further still when both f0 and amplitude envelope cues were applied. These results confirm the importance of f0 information (at least under simulated EAS) and indicate that significant information can be provided by a tone that tracks f0 or f0 and amplitude envelope cues. [Work supported in part by NIH.]
Multiple echoes precedence effect
Authors: Yu Gongqiang , Litovsky Ruth Y.
Published: October 2013

The precedence effect has been explored extensively using a lead and a single lag (simulated echo). For click stimuli, when the lead-lag delay is a few ms, discrimination of directional changes in the lag are poorer than for the lead. This study was aimed at determining whether the effects would be upheld in a three-source paradigm and to explore the extent to which the three sources interact. Three binaural click pairs (Lead, Lag1, and Lag2) were presented over headphones. Discrimination of directional changes in each click pair was measured using an ABX, 2AFC task, for delays of 0–130 ms. Results replicated classic findings with a single lag, but also showed that (1) for delays above 16 ms a temporal order effect resulted in poorer lead discrimination and better Lag2 discrimination; (2) echo thresholds were complicated by the addition of Lag2; and (3) an interaction was observed between Lag1 and Lag2 at very brief time delays such that summing localization resulted in improved discrimination of lagging sound sources. These results suggest that in a multi-echo situation the directional cues from echoes that occur after the classic lead-lag pair can contribute in the localization process and introduce complexities.
Visual and auditory hemispheric cuing in horizontal sound localization
Authors: Kopčo Norbert , Tomoriová Beáta , Andoga Rudolf
Published: October 2013

Experiments were performed to determine 1) whether a priori information influences sound localization, and 2) whether the influence depends on the modality through which the information is provided. Localization performance was measured for transient auditory stimuli originating in the frontal horizontal plane. In most runs, a cue preceded the stimulus and indicated (correctly or incorrectly) the hemisphere (left vs. right) from which the subsequent target arrived. The cues differed by modality and the cue-to-target onset asynchrony (SOA: 400 to 1600 ms). The listeners were instructed to focus their attention to the cued side. A follow-up experiment evaluated the effect of eye fixation on the visual-cue performance. Results show modality-dependent effects of cuing in terms of both bias and standard deviation in responses. A cue that indicated an incorrect side biased the responses towards its side in both modalities, while a visual correct-side cue caused either no bias or a lateral bias. A visual cue that indicated an incorrect side also caused an increase in the standard deviations at the largest SOA, suggesting that the mechanisms that control auditory spatial attention are modality dependent and that they operate on the time scale of seconds. [Work supported by the Slovak Science Grant Agency.]
The role of suppression in temporal masking effects
Authors: Krishnan Lata A. , Strickland Elizabeth A.
Published: October 2013

The temporal effect refers to the change in signal-to-masker ratio at threshold for a short-duration tone as it is delayed from the onset of a longer-duration masker. Evidence suggests that this phenomenon is related to changes in gain in the cochlea due to acoustic stimulation by the masker. Research has suggested that for off-frequency maskers, the temporal effect is consistent with a decrease in suppression, which may depend on a decrease in gain at the suppressor frequency. Most previous studies have utilized simultaneous masking paradigms to measure the temporal effect. The present study used tonal maskers in a forward masking paradigm, and measured temporal masking curves to elucidate the role of suppression in temporal masking effects. A previous study had also showed that the pattern of the temporal effect with level depended not only on the degree of hearing loss at the signal frequency, but also on the degree of hearing loss above the signal frequency. The present study examined this further by using listeners with normal hearing as well as listeners with a notched cochlear hearing loss. Results will be analyzed in terms of changes in gain at signal and suppressor frequencies. [Work supported by Lions Club McKinney Outreach Award.]
High-frequency radiation from edges and drive points on vibrating panels
Authors: Bliss Donald , Franzoni Linda
Published: October 2013

High-frequency radiation from subsonic waves on vibrating panels is shown to have directivity characteristics that can be expressed analytically by a limited set of parameters. Far-field mean-square pressures are independent of the panel length, indicating the radiation is associated with the edges and drive points. A Fourier transform approach to surface velocity shows that it can be reinterpreted in physical space in terms of singularity functions at the edges, namely the delta function and its derivatives. This interpretation leads to monopole, dipole, quadrupole, etc., edge radiators with relative strengths that depend on surface-wave Mach number. The radiation cannot be explained simply in terms of uncancelled volumetric sources at edges and drive points; this often-stated idea is not correct except under very restricted circumstances. A correct physical interpretation of the radiation is provided both in physical space and transform space. Basic directivity patterns are identified, associated with right and left traveling waves and the correlation between them at edges and drive points. The role of boundary conditions at the panel edge is illustrated, as are the effects of forcing. The analytical characterization of the radiation is shown to be particularly straightforward in the high-frequency broadband limit.