bluuebunny/crossref_metadata_2025 huggingface dataset:
Rehabilitation of a Bauxite Tailing Substrate in Central Amazonia: The Effect of Litter and Seed Addition on Flood‐Prone Forest Restoration
Authors: Dias André T.C. , Bozelli Reinaldo L. , Darigo Ricardo M. , Esteves Francisco de A. , dos Santos Heraldo F. , Figueiredo‐Barros Marcos P. , Nunes Maria Fernanda Q. S. , Roland Fabio , Zamith Luiz R. , Scarano Fabio R.
Published: July 2011

Impacts of mining activity can be particularly difficult to remediate in wetland ecosystems subject to inundation pulses due to the reduced length of the plant growing season. We used a factorial experiment to test whether litter and seed addition could be used to increase the efficiency of ecological restoration on a flood‐prone forest (known as igapó) impacted by deposition of bauxite tailings. Our results clearly showed that the addition of litter collected from pristine igapó areas increased plant growth, seedling density, and seedling species richness. The increase in individual plant growth was echoed at the community level with higher leaf area index values on litter addition plots compared to controls. Litter addition can enhance reaccumulation of nutrient pools during successional development, which has been proposed as an important feature to ensure self‐sustainability of areas under restoration. The success of the seed addition treatment depended on the species used. Of the seven sown species, only Acosmium nitens (a leguminous nitrogen‐fixing species) showed high establishment. The introduction of nitrogen‐fixing species is also expected to build up the nitrogen pool in the system as has been reported for restoration programs in non‐inundated forests. These practices have the advantage, compared to direct fertilizing, of not causing eutrophication of water bodies when applied to flood‐prone vegetation.
The Importance of Asymmetric Tax Policy and Dangers of Aggregation
Authors: JUDD KENNETH L.
Published: July 2011

Existing tax policies have many complex features that make distinctions across goods, factors, and financial structures that distort economic allocations. Their importance is ignored when tax policy is summarized by an “effective” tax rate. In fact, the losses due to asymmetries are often larger than the losses due to the level of taxation.
Production of monocytic cells from bone marrow stem cells: therapeutic usage in Alzheimer’s disease
Authors: Magga Johanna , Savchenko Ekaterina , Malm Tarja , Rolova Taisia , Pollari Eveliina , Valonen Piia , Lehtonen Šárka , Jantunen Esa , Aarnio Jussi , Lehenkari Petri , Koistinaho Milla , Muona Anu , Koistinaho Jari
Published: July 2011

Accumulation of amyloid β (Aβ) is a major hallmark in Alzheimer’s disease (AD). Bone marrow derived monocytic cells (BMM) have been shown to reduce Aβ burden in mouse models of AD, alleviating the AD pathology. BMM have been shown to be more efficient phagocytes in AD than the endogenous brain microglia. Because BMM have a natural tendency to infiltrate into the injured area, they could be regarded as optimal candidates for cell‐based therapy in AD. In this study, we describe a method to obtain monocytic cells from BM‐derived haematopoietic stem cells (HSC). Mouse or human HSC were isolated and differentiated in the presence of macrophage colony stimulating factor (MCSF). The cells were characterized by assessing the expression profile of monocyte markers and cytokine response to inflammatory stimulus. The phagocytic capacity was determined with Aβ uptake assay in vitro and Aβ degradation assay of natively formed Aβ deposits ex vivo and in a transgenic APdE9 mouse model of AD in vivo. HSC were lentivirally transduced with enhanced green fluorescent protein (eGFP) to determine the effect of gene modification on the potential of HSC‐derived cells for therapeutic purposes. HSC‐derived monocytic cells (HSCM) displayed inflammatory responses comparable to microglia and peripheral monocytes. We also show that HSCM contributed to Aβ reduction and could be genetically modified without compromising their function. These monocytic cells could be obtained from human BM or mobilized peripheral blood HSC, indicating a potential therapeutic relevance for AD.
Mesenchymal stem cells promote the sustained expression of CD69 on activated T lymphocytes: roles of canonical and non‐canonical NF‐κB signalling
Authors: Saldanha‐Araujo Felipe , Haddad Rodrigo , Farias Kelen C. R. Malmegrim de , Souza Alessandra de Paula Alves , Palma Patrícia V. , Araujo Amélia G. , Orellana Maristela D. , Voltarelli Julio C. , Covas Dimas T. , Zago Marco A. , Panepucci Rodrigo A.
Published: July 2011

Mesenchymal stem cells (MSCs) are known to induce the conversion of activated T cells into regulatory T cells in vitro. The marker CD69 is a target of canonical nuclear factor kappa‐B (NF‐κB) signalling and is transiently expressed upon activation; however, stable CD69 expression defines cells with immunoregulatory properties. Given its enormous therapeutic potential, we explored the molecular mechanisms underlying the induction of regulatory cells by MSCs. Peripheral blood CD3+ T cells were activated and cultured in the presence or absence of MSCs. CD4+ cell mRNA expression was then characterized by microarray analysis. The drug BAY11‐7082 (BAY) and a siRNA against v‐rel reticuloendotheliosis viral oncogene homolog B (RELB) were used to explore the differential roles of canonical and non‐canonical NF‐κB signalling, respectively. Flow cytometry and real‐time PCR were used for analyses. Genes with immunoregulatory functions, CD69 and non‐canonical NF‐κB subunits (RELB and NFKB2) were all expressed at higher levels in lymphocytes co‐cultured with MSCs. The frequency of CD69+ cells among lymphocytes cultured alone progressively decreased after activation. In contrast, the frequency of CD69+ cells increased significantly following activation in lymphocytes co‐cultured with MSCs. Inhibition of canonical NF‐κB signalling by BAY immediately following activation blocked the induction of CD69; however, inhibition of canonical NF‐κB signalling on the third day further induced the expression of CD69. Furthermore, late expression of CD69 was inhibited by RELB siRNA. These results indicate that the canonical NF‐κB pathway controls the early expression of CD69 after activation; however, in an immunoregulatory context, late and sustained CD69 expression is promoted by the non‐canonical pathway and is inhibited by canonical NF‐κB signalling.
Genetic estimates of population structure and dispersal in a benthic stream fish
Authors: Lamphere Bradley A. , Blum Michael J.
Published: July 2011

Abstract–  Comparing genetic and demographic estimates of dispersal in freshwater fish can improve understanding of movement distributions and population connectivity. Here we examined genetic variation among mottled sculpin (Cottus bairdi) in the Nantahala River (North Carolina, USA) to compare genetic estimates of dispersal with estimates derived from mark–recapture studies of individual movement. Microsatellite‐based analysis of gene flow revealed evidence of strong isolation by distance among locations spanning only 5.6 km and limited dispersal among clusters of sites separated by swift cascades. Estimates of between‐cluster contemporary dispersal rates derived from Bayesian assignment tests ranged from 1% to 6%, with most movement occurring among adjacent clusters in a downstream direction. Evidence of a long‐term net immigration asymmetry and decreasing genetic diversity from downstream to upstream locations indicates that historical patterns of stream colonisation contrast with contemporary dispersal patterns. Our findings are largely consistent with predictions from individual movement patterns but suggest that long moves (>500 m) are more frequent, and maximum dispersal distances are greater than what has been reported from mark–recapture studies. The discrepancy may reflect spatial limitations of mark–recapture methods or temporal variation in dispersal in individuals and populations.
CONTRAST MEDIA ENHANCEMENT OF INTRACRANIAL LESIONS IN MAGNETIC RESONANCE IMAGING DOES NOT REFLECT HISTOPATHOLOGIC FINDINGS CONSISTENTLY
Authors: BRUNNER SINGH JEANNINE , OEVERMANN ANNA , LANG JOHANN , VANDEVELDE MARC , DOHERR MARCUS , HENKE DIANA , GORGAS DANIELA
Published: July 2011

Certain magnetic resonance (MR) enhancement patterns are often considered to be associated with a specific diagnosis but experience shows that this association is not always consistent. Therefore, it is not clear how reliably contrast enhancement patterns correlate with specific tissue changes. We investigated the detailed histomorphologic findings of intracranial lesions in relation to Gadodiamide contrast enhancement in 55 lesions from 55 patients, nine cats, and 46 dogs. Lesions were divided into areas according to their contrast enhancement; therefore 81 areas resulted from the 55 lesions which were directly compared with histopathology. In 40 of 55 lesions (73%), the histomorphologic features explained the contrast enhancement pattern. In particular, vascular proliferation and dilated vessels occurred significantly more often in areas with enhancement than in areas without enhancement (P=0.044). In 15 lesions, there was no association between MR images and histologic findings. In particular, contrast enhancement was found within necrotic areas (10 areas) and ring enhancement was seen in lesions without central necrosis (five lesions). These findings imply that necrosis cannot be differentiated reliably from viable tissue based on postcontrast images. Diffusion of contrast medium within lesions and time delays after contrast medium administration probably play important roles in the presence and patterns of contrast enhancement. Thus, histologic features of lesions cannot be predicted solely by contrast enhancement patterns.
Preventing recurrent cerebrovascular events in patients with stroke or transient ischemic attack: The current data
Authors: Bergman Deborah
Published: July 2011

Purpose: To describe recurrent stroke in relation to the current data, treatment guidelines, diagnostic considerations, risk prevention, and management for the nurse practitioner (NP).

Data sources: An extensive review of the scientific literature, clinical trials, and clinical guidelines.

Conclusions: Recurrent stroke is a major health concern. A first ischemic cerebrovascular event or transient ischemic attack (TIA) is a risk factor for future strokes.

Implications for practice: The risk of recurring stroke has been demonstrated in multiple studies, yet only approximately 5% of stroke patients receive appropriate therapy in a timely manner. The stroke or TIA workup should be completed quickly so that the appropriate treatments and interventions can be initiated to reduce the risk of an additional event. The etiology of the stroke and identification of personal risk factors are important because treatment depends on the specific stroke mechanism. A variety of antiplatelet trials have specific implications for stroke and recurrent stroke. Present treatments include aspirin, aspirin plus extended‐release dipyridamole and clopidogrel. The NP plays an important role in ongoing patient education about symptoms, the long‐term management of the patient, and reduction of future stroke risk.
Population structure of island‐associated dolphins: Evidence from mitochondrial and microsatellite markers for common bottlenose dolphins (Tursiops truncatus) around the main Hawaiian Islands
Authors: Martien Karen K. , Baird Robin W. , Hedrick Nicole M. , Gorgone Antoinette M. , Thieleking Janet L. , McSweeney Daniel J. , Robertson Kelly M. , Webster Daniel L.
Published: July 2011

Abstract

We used mitochondrial and nuclear genetic markers to investigate population structure of common bottlenose dolphins, Tursiops truncatus, around the main Hawaiian Islands. Though broadly distributed throughout the world's oceans, bottlenose dolphins are known to form small populations in coastal waters. Recent photo‐identification data suggest the same is true in Hawaiian waters. We found genetic differentiation among (mtDNA ΦST= 0.014–0.141, microsatellite F’ST= 0.019–0.050) and low dispersal rates between (0.17–5.77 dispersers per generation) the main Hawaiian Island groups. Our results are consistent with movement rates estimated from photo‐identification data and suggest that each island group supports a demographically independent population. Inclusion in our analyses of samples collected near Palmyra Atoll provided evidence that the Hawaiian Islands are also occasionally visited by members of a genetically distinct, pelagic population. Two of our samples exhibited evidence of partial ancestry from Indo‐Pacific bottlenose dolphins (T. aduncus), a species not known to inhabit the Hawaiian Archipelago. Our findings have important implications for the management of Hawaiian bottlenose dolphins and raise concerns about the vulnerability to human impacts of pelagic species in island ecosystems.
Epidemiological study of colorectal adenoma and cancer in symptomatic patients in China between 1990 and 2009
Authors: CHEN Hui Min , WENG Yu Rong , JIANG Bo , SHENG Jian Qiu , ZHENG Ping , YU Cheng Gong , FANG Jing Yuan
Published: July 2011

OBJECTIVE:  The best cure for colorectal cancer (CRC) lies on its early diagnosis and treatment. We aimed to provide the epidemiological features of advanced colorectal adenoma (A‐CRA) and CRC in symptomatic patients and to determine whether the incidences of A‐CRA and CRC increased simultaneously in China between 1990 and 2009.

METHODS:  A total of 157 943 patients who had undergone a colonoscopy from 1990 to 2009 were enrolled, of which 6 777 patients had A‐CRA and 3 503 had CRC. They were compared with controls in a stratified analysis. The detection rates of A‐CRA and CRC in the 1990s and 2000s were also compared.

RESULTS:  The detection rate of A‐CRA increased 1.88‐fold over the two decades, while that of CRC increased 0.66‐fold. The percentages of patients with A‐CRA and CRC who were elder than 50 years were significantly higher in the 2000s than those in the 1990s (P = 0.000). The changes of location of A‐CRA and CRC during the two decades indicated a shift of lesions from the distal colon to proximal colon.

CONCLUSION:  There was a significant increase in detection rate of A‐CRA in the 2000s, but CRC did not increase at a similar speed. Our results indicated that the early detection and removal of colorectal adenoma in symptomatic patients might decrease the incidence of CRC.
Permanent Genetic Resources added to Molecular Ecology Resources Database 1 April 2011–31 May 2011
Authors:   Molecular Ecology Resources Primer Development Consortium,, BONIZZONI MARIANGELA , BOURJEA JÉRÔME , CHEN BIN , CRAIN B. J. , CUI LIWANG , FIORENTINO V. , HARTMANN S. , HENDRICKS S. , KETMAIER V. , MA XIAOGUANG , MUTHS DELPHINE , PAVESI L. , PFAUTSCH S. , RIEGER M. A. , SANTONASTASO T. , SATTABONGKOT JETSUMON , TARON C. H. , TARON D. J. , TIEDEMANN R. , YAN GUIYUN , ZHENG BIN , ZHONG DAIBIN
Published: July 2011

This article documents the addition of 92 microsatellite marker loci to the Molecular Ecology Resources Database. Loci were developed for the following species: Anopheles minimus, An. sinensis, An. dirus, Calephelis mutica, Lutjanus kasmira, Murella muralis and Orchestia montagui. These loci were cross‐tested on the following species: Calephelis arizonensi, Calephelis borealis, Calephelis nemesis, Calephelis virginiensis and Lutjanus bengalensis.
Searching for evidence of selection in avian DNA barcodes
Authors: KERR KEVIN C. R.
Published: July 2011

The barcode of life project has assembled a tremendous number of mitochondrial cytochrome c oxidase I (COI) sequences. Although these sequences were gathered to develop a DNA‐based system for species identification, it has been suggested that further biological inferences may also be derived from this wealth of data. Recurrent selective sweeps have been invoked as an evolutionary mechanism to explain limited intraspecific COI diversity, particularly in birds, but this hypothesis has not been formally tested. In this study, I collated COI sequences from previous barcoding studies on birds and tested them for evidence of selection. Using this expanded data set, I re‐examined the relationships between intraspecific diversity and interspecific divergence and sampling effort, respectively. I employed the McDonald‐Kreitman test to test for neutrality in sequence evolution between closely related pairs of species. Because amino acid sequences were generally constrained between closely related pairs, I also included broader intra‐order comparisons to quantify patterns of protein variation in avian COI sequences. Lastly, using 22 published whole mitochondrial genomes, I compared the evolutionary rate of COI against the other 12 protein‐coding mitochondrial genes to assess intragenomic variability. I found no conclusive evidence of selective sweeps. Most evidence pointed to an overall trend of strong purifying selection and functional constraint. The COI protein did vary across the class Aves, but to a very limited extent. COI was the least variable gene in the mitochondrial genome, suggesting that other genes might be more informative for probing factors constraining mitochondrial variation within species.
The pleiotropic roles of autophagy regulators in melanogenesis
Authors: Ho Hsiang , Ganesan Anand K.
Published: July 2011

Melanin pigments protect the skin and eyes from toxic insults and are critical for the normal functioning of multiple organ systems including the skin, eyes, and brain. Biochemical and genetic studies in both human and mice have revealed the molecular machinery controlling the transcription of genes encoding enzymes that produce melanin and the trafficking of these enzymes to the melanosome, a lysosome‐related organelle dedicated to melanin synthesis. Recent functional genomic studies have identified a role for genes previously known to regulate autophagy, a cellular process that facilitates nutrient recycling during starvation, in the biogenesis of melanosomes in vitro and in vivo. In this review, we describe the pleiotropic roles of autophagy regulators in multiple vesicle trafficking processes, define a specific role for autophagy regulators in melanosome biogenesis, and shed light on how autophagy and autophagy regulators may play different roles in both the biogenesis of melanosomes and melanosome destruction.
Design of Microscale Heat and Mass Exchangers for Absorption Space Conditioning Applications
Authors: Nagavarapu Ananda Krishna , Garimella Srinivas
Published: July 2011

This paper presents the development of a miniaturization technology for heat and mass exchangers used in absorption heat pumps. The exchanger consists of an array of parallel, aligned alternating shims with integral microscale features, enclosed between cover plates. These microscale features facilitate the flow of the various fluid streams and the associated heat and mass transfer. In an absorber application, effective vapor and solution contact and microscale features for the flow of both the solution and the coolant induce high heat and mass transfer rates without any active or passive surface enhancement. The geometry ensures even flow distribution with minimal overall pressure drops. A model of the coupled heat and mass transfer process for ammonia-water absorbers using this configuration under typical operating conditions demonstrates the potential for extremely small absorption components. The proposed concept is compact, modular, versatile, and in an eventual implementation, can be mass produced. Additionally, the same concept can be extended to the other absorption heat pump components as well as for several other industries involved in multicomponent fluid processes.
Experimental Investigation of Conjugate Heat Transfer in a Rib-Roughened Trailing Edge Channel With Crossing Jets
Authors: Coletti Filippo , Scialanga Manfredi , Arts Tony
Published: July 2011

The present contribution is devoted to the experimental study of the conjugate heat transfer in a turbine blade cooling cavity located near the trailing edge. The cooling scheme is characterized by a trapezoidal cross-section, one rib-roughened wall, and slots along two opposite walls. The Reynolds number, defined at the inlet of the test section, is set at 67,500 for all the experiments. The values of all the important nondimensional parameters characterizing the experiment, including the solid-to-fluid conductivity ratio, are engine-representative. Uniform heat flux is imposed along the outer side of the rib-roughened wall. The measurements are performed using three different ribbed walls, with thermal conductivities ranging from 1 W m−1 K−1 to 18 W m−1 K−1. Highly resolved distributions of nondimensional temperature and Nusselt number over the rib-roughened wall are obtained by means of infrared thermography and finite element analysis. The impact of the conduction through the wall on the thermal performance is demonstrated by comparison with purely convective results, previously published by the authors on the same configuration.
Tribological Characteristics Modification of Magnetorheological Fluid
Authors: Lee Chul Hee , Lee Deuk Won , Choi Jae Young , Choi Seung Bok , Cho Won Oh , Yun Hyuk Chae
Published: July 2011

Recently, research on the application of magnetorheological (MR) fluid in mechanical engineering has been widely expanded, while the performance of MR fluid in tribology has also been investigated. In this study, a modification of MR fluid, which is modified by adding certain additives, is attempted to improve tribological performance. After modification, wear and friction are measured by four-ball wear tester and linear-oscillation (SRV) tester under no magnetic fields. Subsequently, the oxidation induction time (OIT) is evaluated by pressure differential scanning calorimetry (PDSC). Then, to observe the tribological performance under magnetic fields, pin-on-disk test is conducted to confirm the effects of the commercial MR fluid and modified MR fluid on friction and wear in different operating and magnetic conditions. Also, the modification effects on surface roughness are investigated by using a profilometer. Moreover, the microscopic changes of surfaces and MR particles are investigated by using scanning electron microscopy (SEM).
Utilization of Advanced Working Fluids With Biporous Evaporators
Authors: Reilly Sean W. , Catton Ivan
Published: July 2011

A novel fluid for use as a working fluid in a heat pipe has been tested at UCLA. The fluid was discovered originally in use with a device consisting of a metal tube charged with the patented inorganic aqueous solution (IAS), which is evaporated when the tube is evacuated before use. According to the patent, this evaporation leaves a thin film that allows the tube to carry high heat flux loads with low temperature drop across the tube in a solid state mode. However, various experiments with these tubes have produced inconsistent results, and there are some questions as to whether the fluid is completely evaporated. The research on which this work is based is focused on testing whether the charging fluid will operate as the working fluid in a heat pipe, in order to determine the nature of the IAS fluid. A heat pipe apparatus was charged with a biporous wick in order to investigate if the fluid plays a role in heat transfer. There are extensive data for this experiment using water as the working fluid, which will be used to compare the two sets of results. Testing has shown a reduction of the superheat required to drive heat fluxes through a wick compared to water by approximately 40%. Some experiments have shown that the operating (temperature) range of the IAS is much larger than a standard heat pipe. It is theorized that the increase in performance of the IAS is due to an increased thermal conductivity of the wick and increased capillarity. If this fluid is proven to be effective, it would lead to more effective and tunable heat transfer devices.
Slow‐rotation dynamic SPECT with a temporal second derivative constraint
Authors: Humphries T. , Celler A. , Trummer M.
Published: July 2011

Purpose:

Dynamic tracer behavior in the human body arises as a result of continuous physiological processes. Hence, the change in tracer concentration within a region of interest (ROI) should follow a smooth curve. The authors propose a modification to an existing slow‐rotation dynamic SPECT reconstruction algorithm (dSPECT) with the goal of improving the smoothness of time activity curves (TACs) and other properties of the reconstructed image.

Methods:

The new method, denoted EM, imposes a constraint on the second derivative (concavity) of the TAC in every voxel of the reconstructed image, allowing it to change sign at most once. Further constraints are enforced to prevent other nonphysical behaviors from arising. The new method is compared with dSPECT using digital phantom simulations and experimental dynamic 99mTc ‐DTPA renal SPECT data, to assess any improvement in image quality.

Results:

In both phantom simulations and healthy volunteer experiments, the EM method provides smoother TACs than dSPECT, with more consistent shapes in regions with dynamic behavior. Magnitudes of TACs within an ROI still vary noticeably in both dSPECT and EM images, but also in images produced using an OSEM approach that reconstructs each time frame individually, based on much more complete projection data. TACs produced by averaging over a region are similar using either method, even for small ROIs. Results for experimental renal data show expected behavior in images produced by both methods, with EM providing somewhat smoother mean TACs and more consistent TAC shapes.

Conclusions:

The EM method is successful in improving the smoothness of time activity curves obtained from the reconstruction, as well as improving consistency of TAC shapes within ROIs.
Reverberation modeling workshops.
Authors: Perkins John S. , Thorsos Eric I.
Published: July 2011

To evaluate progress made in basic and applied underwater acoustic reverberation modeling and to make recommendations for transitions to operational systems, a series of two reverberation modeling workshops (RMWs) was held (the last in May 2008). A basic goal of the RMWs was to provide well-defined problems and consensus solutions to support verification and validation for new models, upgrades to Navy Standard models, and geoacoustic inversion techniques based on reverberation data. The basic problem in designing the workshop was that even the simplest reverberation problems of interest to the Navy do not have closed form solutions and are still (essentially) beyond our computational capabilities to solve using standard “exact” numerical techniques. All current, practical underwater reverberation models replace the physical problem by employing scattering and loss functions or tables. We discuss the development of a sequence of well-defined problems (physics-based), with the equivalent loss/scattering input, which increases in complexity. We also discuss the lessons learned in this process and point out some of the unexpected results from the workshops, and make recommendations for future benchmarking workshops. [Work supported by the Office of Naval Research.]
Real-time auralization of wave simulation in complex three-dimensional acoustic spaces.
Authors: Raghuvanshi Nikunj , Snyder John , Mehra Ravish , Lin Ming C. , Govindaraju Naga K.
Published: July 2011

A technique has been developed for modeling real-time sound propagation in static acoustic spaces that relies on pre-computed wave simulation. The associated system can auralize propagation that includes diffraction, interference, scattering and late reverberation, while supporting tens of moving point sources and moving listener in highly complex three-dimensional scenes. Since direct storage of simulated impulse responses for runtime use is infeasible, a novel technique was developed to extract and compactly encode the perceptually salient information in the simulated band-limited impulse responses. The response is automatically broken into early reflections (ERs) and late reverberation (LR), via a threshold on the temporal density of arriving wave-fronts. The LR is simulated and stored once per room. Detailed spatial variation in ER is simulated, and encoded by a set of peak delays/amplitudes in the time domain and a residual frequency response sampled in octave bands, at each source/receiver point pair on a five-dimensional grid. An efficient run-time uses this pre-computed representation to perform binaural sound rendering based on frequency-domain convolution. The system demonstrates audible wave-based effects in real time—diffraction low-pass filtering behind obstructions, sound focusing (caustics), hollow reverberation in empty rooms, sound diffusion in fully-furnished rooms, and late reverberation with non-exponential decay.
Ocean traffic noise in the context of natural ambient noise in impacts on marine mammals.
Authors: Cato Douglas H.
Published: July 2011

Traffic noise, the background noise from distance shipping, is the most widespread anthropogenic component of ambient noise. There has been concern for decades that traffic noise may be limiting the ability of marine mammals to communicate, but there is little direct evidence of actual impacts or the significance of these on the well being of populations, possibly because of the difficulties in obtaining such evidence. This paper compares traffic noise with natural ambient noise in the same frequency band. Marine mammals have evolved to cope with the range of levels in natural ambient noise. It draws on studies from areas near Australia where there is a wide range in traffic noise levels. In some areas, traffic noise is so low that it is possible to determine the range of natural ambient noise in the frequency band where traffic noise usually dominates. In other areas, traffic noise reaches levels similar to some of the high levels observed near North America. Humpback whales that migrate along the east coast of Australia are subject to high levels of traffic noise and noise from passing ships, but there seems to be little impact on the whales at the population level.
A brief personal introduction to the history and status of the ocean observing system and acoustical measurements.
Authors: Dushaw Brian D. , Duda Timothy F.
Published: July 2011

Integrated ocean observing systems (IOOSs) originated during the early 1990s as a way to provide valuable information to society as return on decades of investment in oceanographic research. The archetypical Argo program (www.argo.ucsd.edu) was initiated following the landmark OceanObs’99 conference and reassessed during OceanObs’09. With the possibility of significant sustained funding for comprehensive oceanic observations, one hallmark of planning conferences has been their political overtones. Regional ocean observing systems (www.ioos.gov, www.usnfra.org, and www.nanoos.org), purposely distinct from NOAA, began to develop in the early 2000s. The OOSes are not research programs, but sustained monitoring and information-providing services. The ocean observing initiative (OOI) developed out of the deep earth observing system (DEOS) idea of the early 2000s to deploy platforms over the world’s oceans for geophysical research. With the advent of significant funding for such platforms, the geophysical thrust was thrust aside in favor of two components: the undersea cabled networks and a small set of “Pioneer” platforms for oceanographic research. There has been little representation of acoustical techniques in these programs. Successful implementation of acoustical components for the IOOS requires the sustained cooperation and encouragement of three factions: the oceanographic community, the national and state funding agencies, and the acoustics community.
Listening to marine mammals at basin to local scales.
Authors: Moore Sue E. , Van Parijs Sofie M. , Southall Brandon L. , Stafford Kathleen M.
Published: July 2011

The successful use of SOSUS to track broad-scale occurrence patterns in whale calls during the second half of the 20th century fostered the development of autonomous recorders that can be deployed virtually anywhere in the world ocean. Over the past decade, data from these recorders have provided dramatic insights to marine mammal ecology. Patterns of call reception have demonstrated the near year-round occurrence of some baleen whale species in Arctic and Antarctic waters, a discovery that challenges long-held assumptions about the phenology of seasonal migrations. Integration of year-long calling records with physical oceanographic measures at mooring-based ocean observatories provides a means to include large whales in ecosystem-based models. The reception of anthropogenic sounds on nearly all recorders, whether deployed in coastal or remote areas, emphasizes the need to develop regional “soundscapes” based upon integrative sampling and analytical protocols. Examples from several long-term research programs will be provided as the basis for the strong assertion that passive acoustic observation of marine mammals is a vital component of any ocean observing system. Opportunities for future collaborations and the challenges of data management and access will be discussed.
Broadband acoustics on the VENUS observatory in Saanich Inlet.
Authors: Ross Tetjana , Lee Wu-Jung , Keister Julie , Lara Lopez Ana , Greene Charles
Published: July 2011

High-frequency sonar is by far the most cost-effective way of “profiling” the water column from an ocean observing system. From a biological oceanographic perspective, long-term acoustic observations are rich with information on the depths and abundances of fish and zooplankton. The drawback is that it is difficult to conclusively identify which species (or even functional groups) are present at any given time. This can be done, but only with plenty of supporting data, generally acquired non-autonomously. Broadband acoustics may be the key to making acoustic observations of fish and zooplankton less qualitative. Here we explore this idea. We present nearly two years (Apr. 2008–Feb. 2010) of broadband (85–155 kHz) echosounder data collected on the VENUS observatory in Saanich Inlet. Using historical and contemporaneous (July 30, 2009) zooplankton net-tow data, we attempt to automate and interpret the resulting classification of scattering layers throughout the long-term record.
Cabled observatory vent imaging sonar.
Authors: Light Russell , Miller Vernon , Jackson Darrell R. , Rona Peter A. , Bemis Karen G.
Published: July 2011

A cabled observatory vent imaging sonar (COVIS) has been developed to provide plume and Doppler imaging of hydrothermal vents and surrounding diffuse flow. The system was designed to be compatible with the power and data interface standards of the Neptune Canada cabled observatory. COVIS is a 4 m tall, titanium tripod employing a Reson 7125 multibeam sonar. The sonar transducers are positioned by a motor-driven three degree of freedom rotation system (pitch, roll, and yaw). A 400 kHz, 1 × 128 deg fan-beam projector is used with a receiver array that forms 256 beams having horizontal width 0.5 deg and covering a 128 deg azimuthal sector. Volumetric imaging of plumes is generated as the transducer array is scanned in 1 deg pitch steps. Doppler measurements of flow velocity over a 3-D grid are also derived. A 200 kHz, 28 × 128° broad beam projector is used to image the diffuse areas near the base of the hydrothermal vent edifices. Software allows for the creation of complex, arbitrary, autonomously executed experiments that control all aspects of the sonar and rotation system. COVIS was successfully deployed in September 2010. The design of COVIS provides insights relevant to future cabled acoustic systems. [Work supported by NSF.]
Holmium: YAG lithotripsy varies with power settings.
Authors: Teichman Joel M. H. , Sea Jason , Jonat Lee , Chew Ben , Qiu Jinze , Milner Thomas
Published: July 2011

The holmium:YAG laser fragments stones by photothermal mechanism. Increased pulse energy (PE) produces larger ablation craters, implying faster lithotripsy. However, increased PE increases retropulsion, implying slower lithotripsy. Optimal power settings were studied. Uniform stone phantoms were ablated in water (500 J total energy). Six power settings were tested: ranging from 0.2 to 2.0 at 10–40 Hz. Two conditions were tested: no stabilization vs stabilization devices placed behind the stone. Total fragmentation (TF) and fragment sizes were quantified. In the no stabilization cohorts, retropulsion was measured. Pressure transients were measured by needle hydrophone. Stone crater volumes were quantified by optical computed tomography. With or without stabilization, TF increased as PE increased, p<0.0001; and fragment size increased as PE increased, p<0.05. Without stabilization, retropulsion increased as PE increased, p<0.0001. TF was greater with vs without stabilization, p<0.01. Pressure transients were <30 bars even at 2.0 J. Crater volumes increased as PE increased, p<0.01 but remained symmetric. Increased PE produces more lithotripsy but also larger fragments. Even at high PE (2.0 J) Ho:YAG lithotripsy is photothermal. Low PE produces small fragments but less lithotripsy. Modest PE (0.2–0.5 J) at high-repetition rate produces more fragmentation, small fragments, and less retropulsion. [Work supported by Percsys and Boston Scientific.]
Interrogating and imaging renal stones using vibro-acoustography.
Authors: Illian Paul R. , Gross Dan , Lu Wei , Owen Neil R. , Bailey Michael R. , Mourad Pierre D.
Published: July 2011

Vibro-acoustography (VA) is an ultrasound interrogation and imaging technique with a variety of applications. Here it was used to identify optimal parameters for detecting and imaging kidney stones in phantoms. The parameters varied included the difference frequency and the position in time of the analysis window used for image construction. Experiments in a water tank were conducted using a focused PVDF membrane hydrophone (receiver) placed in a central opening of an annular, dual element transducer (source), itself mounted on a translation stage. Our source consisted of 90-ms pulses with a center frequency of 2.0 MHz and difference frequencies between 50 and 350 kHz, applied both on and off stone. Variations in the amplitude of the measured ultrasound backscatter and acoustic emissions as a function of difference frequency, between signals from stone and phantom, guided the choice of imaging parameters. The results were detailed images of renal stones measuring 10 dB above the background tissue. These findings suggest that spectral information from the scattering and reverberation of VA induced ultrasound can be used to guide the interrogation and imaging of kidney stones. [Work supported by NIH DK43881, NIH DK086371, and NSBRI through NASA NCC 9-58].
Location of coupling defects influences stone breakage in shock wave lithotripsy.
Authors: Li Guangyan , McAteer James A. , Williams James C.
Published: July 2011

SWL is the most common treatment for kidney stones. However, compared to ureteroscopy and nephrostolithotomy, SWL is least effective—failing in ∼50% of cases. Since stone breakage is highly effective under controlled conditions, acoustic coupling between the lithotripter and patient may be the weak link. Previous in vitro studies determined that air-pockets created in routine coupling reduce SW-amplitude by ∼20% and defects occupying only 2% of coupling area reduced breakage 20%–40%. As a step toward determining if the position of defects influences SW delivery to the target we used styrofoam to selectively block portions of the coupling interface between a DoLi-50 and the test tank. Stone breakage was ∼three times greater when the entire 13 cm diameter coupling interface was unblocked than when all but the center 6 cm was blocked, consistent with the reduction in surface area. However, the transition was abrupt, with ∼70% of the loss in efficacy occurring upon reduction in the aperture from 7 to 6 cm. Reducing the aperture had a greater effect on P− than P+ (P+/P− no aperture ∼41/−4.3 MPa; 7 cm ∼42/−3.5 MPa; 6 cm ∼37/−2.5 MPa). These initial findings begin to identify a region of the overall coupling interface where defects are likely to be problematic. [Work supported by Grant No. NIH-DK43881.]
Sound fields inside street canyons with inclined flanking building facades.
Authors: Tang S. K. , Piippo K. E.
Published: July 2011

Street canyons are common in modern cities. It is well known that the multiple sound reflections within the canyons tend to increase the noise levels inside the canyons. A scaled down model experiment was conducted in the present investigation to study the effect of the inclination of building facade on the sound field. A line source consisted of 100 2-in. aperture loudspeakers was used to simulate the road traffic source. The whole experiment was carried out inside an anechoic chamber. The canyon was 4 m long, 2 m high, and 1 m wide (1:4 scale down ratio). The case of a single facade was used acted as the reference. The reverberation inside the model canyon was strong when the two model facades are vertical (inclination 90 deg) and parallel to each other. However, it was found that such reverberation deteriorated very rapidly as the inclination of one of the model facade was reduced to 80 deg. The sound strength inside the model canyon was also reduced. The sound levels at the top region of the canyon decreased more rapidly. It was also found that the effect of the opposite facade was basically unchanged once its inclination was less than 60 deg.
Radiation torque on solid spheres and drops centered on an acoustic helicoidal Bessel beam.
Authors: Zhang Likun , Marston Philip L.
Published: July 2011

Somewhat analogous to circularly polarized electromagnetic waves carrying axial angular momentum and generating a corresponding torque, a helicoidal acoustic (vortex) beam also carries axial angular momentum and absorption of such a beam should also produce an axial radiation torque [B. T. Hefner and P. L. Marston, J. Acoust Soc. Am. 106, 3313–3316 (1999)]. Here the acoustic radiation torque on solid spheres and spherical liquid drops centered on acoustic helicoidal Bessel beams is analyzed. Using a relation between the scattering and the partial wave coefficients for a sphere in a helicoidal Bessel beam, the torque is predicted to be proportional to the ratio of the absorbed power to the acoustic frequency. Calculations suggest that beams with a low topological charge tend to be more efficient for generating torques on solid spheres for all frequencies and on liquid drops in the low frequency regime. Balanced by drag torque, a steady rotation is generated. Calculations of the steady-state angular velocity suggest that the rotation in this type of traveling wave beam could be significant using appropriate frequencies. [Work supported in part by NASA.]
Effect of internal pressure on the vibrational response of a fluid-filled spherical shell: Experiment.
Authors: Piacsek Andrew A. , Taylor Robert P.
Published: July 2011

The resonance frequencies of a spherical aluminum shell (radius 3.0 in., thickness 1/8 in.) filled with water have been measured for several different values of static water pressure. It is found that a pressure increase of 100 psi causes resonance frequencies associated with axisymmetric bending modes to shift higher by about 0.15%, consistent with predictions of elastic shell theory [DiGiovanni and Dugundji, Air Force Office of Scientific Research Report No. 65-0640 (1965). The shell is suspended by elastic cords attached to an inlet valve and is excited acoustically with a swept sine wave; the vibrational response is measured with small accelerometers mounted on the shell surface. Techniques for identifying frequency shifts associated with very small pressure changes (less than 1 psi) will be discussed. The effect reported here may have an application in the development of noninvasive methods for measuring intracranial pressure changes. [Work supported by National Science Foundation STEM program and Central Washington University.]
Measurement and modeling of high frequency sound speed and attenuation in sandy sediments since the Sediment Acoustics Experiment 1999.
Authors: Hefner Brian T.
Published: July 2011

During the Sediment Acoustics Experiment in 1999 (SAX99), measurements were made of the sound speed and attenuation in a sandy sediment, supplemented by detailed environmental characterization. While the dispersion was consistent with Biot theory, the attenuation at high frequencies had a linear frequency dependence that was consistent with models based on losses at grain contacts. These results led to the development of a number of competing models of sound propagation in sand sediments. Subsequent to SAX99, measurements of sound speed and attenuation have been made in several ocean sediments as well as in a number of laboratory sediments composed of either sand or glass beads. Many of these experiments have been accompanied by careful measurements of the sediment properties and, in some cases, these properties have been varied to assess their impact on sound propagation. An overview of these results will be given and the implications of these measurements for high frequency sediment acoustics modeling will be discussed. [Work supported by the Office of Naval Research.]
The myth that sediment mean grain size provides a useful prediction of high-frequency acoustic bottom-interaction.
Authors: Richardson Michael
Published: July 2011

Mean grain size is the most common descriptor found in seafloor databases and is often the only sediment description available to acoustic modelers. Grain size (phi) is traditionally characterized by a base-2 logarithmic scale. This makes geological sense, as natural processes including weathering and transport tend to create lognormal distributions of particles. The mean describes the central tendency of phi-transformed size distributions and values of sorting, skewness, and kurtosis describe deviations from lognormal distributions. The presence of two or more grain size modes is often evident in grain size histograms. Packing in sand, compaction in mud, and sorting in sand/mud mixtures explain the high variability in mean grain size, density (porosity) relationships. Density provides a better predictor of reflection from and propagation within the seafloor. Although sediment transport is dependent on grain size, seafloor roughness characterized either by rms height or values of spectral parameters is poorly predicted by grain size. These relationships are overwhelmed by temporal variations due to biological and hydrodynamic processes. Prediction of roughness scattering requires concurrent measurements of seafloor roughness. Use of additional grain size statistics and sediment density and understanding the affects of hydrodynamic and biological process should provide better prediction of high-frequency bottom interaction.
Compressional and shear wave modeling in underwater granular media.
Authors: Chotiros Nicholas P. , Isakson Marcia J.
Published: July 2011

A model of attenuation and sound speed in water-saturated granular media, based on a combination of the Biot–Stoll and contact squirt and shear drag model (BICSQS) [Chotiros, and Isakson, J. Acoust. Soc. Am. 116(4), 2011–2022, (2004)] and the frame virtual mass (FVM) model [Chotiros, and Isakson, J. Acoust. Soc. Am. 121(2), EL70 (2007)] is reconciled with the physical dimensions of the area and thickness of the fluid film at the grain-grain contact. The results are consistent with recent experimental observations of enhanced viscosity in nanometer-scale interfacial water films due to molecular mechanics [Goertz et al., Langmuir 23, 5491–5497 (2007)]. The resulting model has a reduced set of input parameters and it is able to match both the sound speed dispersion and attenuation measurements from a large number of sites, including the Sediment Acoustics Experiments (SAX99 and SAX04) in the Gulf of Mexico, the Shallow Water Experiment on the Atlantic coast, and the Yellow Sea [Zhou, J. Acoust. Soc. Am. 78(3) 1003–1009 1985]. [Work supported by the Office of Naval Research, Ocean Acoustics Program.]