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1

Design and characterization of acoustic 4f imaging system by using an optical microring ultrasound detector  

PubMed Central

We propose an acoustic 4f imaging system by using a pair of acoustic lens and an optical microring ultrasound detector (OMUD). The system was designed to have a long range imaging, and the signal strength was enhanced by a factor of ?13 by using an acryl-based acoustic lens at an imaging distance of close to 10 cm. The acoustic signal had a broadband and high frequency spectrum for a given focal distance owing to the unique characteristic of the OMUD. The imaging was obtained without using any reconstruction algorithms. Several performances of the designed system have been investigated by using photo-acoustic microspheres (301 ?m in diameter) which are excited by pulsed laser beam. The resolution of images were compared, which consist of full frequency spectrum and harmonic frequency components. With high frequency (10 MHz and 15 MHz), the images showed consistently better resolutions (440 ?m and 370 ?m) for the microsphere. Frequency analysis of a time-domain signal waveform showed that the signal spectrum of the current system extends up to 20 MHz. PMID:20336169

Baac, Hyoung Won; Ling, Tao; Guo, L. Jay

2010-01-01

2

Nondestructive Acoustic Imaging Techniques  

NASA Astrophysics Data System (ADS)

Acoustic imaging techniques are used in the field of nondestructive testing of technical components to measure defects such as lack of side wall fusion or cracks in welded joints. Data acquisition is performed by a remote-controlled manipulator and a PC for the mass storage of the high-frequency time-of-flight data at each probe position. The quality of the acoustic images and the interpretation relies on the proper understanding of the transmitted wave fronts and the arrangement of the probes in pulse-echo mode or in pitch-and-catch arrangement. The use of the Synthetic Aperture Focusing Technique allows the depth-dependent resolution to be replaced by a depth-independent resolution and the signal-to-noise ratio to be improved. Examples with surface-connected cracks are shown to demonstrate the improved features. The localization accuracy could be improved by entering 2-dimensional or 3-dimensional reconstructed data into the environment of a 3-dimensional CAD drawing. The propagation of ultrasonic waves through austenitic welds is disturbed by the anisotropic and inhomogeneous structure of the material. The effect is more or less severe depending upon the longitudinal or shear wave modes. To optimize the performance of an inspection software tool, a 3-dimensional CAD-Ray program has been implemented, where the shape of the inhomogeneous part of a weld can be simulated together with the grain structure based on the elastic constants. Ray-tracing results are depicted for embedded and for surface-connected defects.

Schmitz, Volker

3

Compressive acoustic imaging with metamaterials.  

PubMed

Compressive imaging has brought revolutionary design methodologies to imaging systems. By shuffling and multiplexing the object information space, the imaging system compresses data on the physical layer and enables employing fewer sensors and acquiring less data than traditional isomorphic mapping imaging systems. Recently metamaterials have been investigated for designing compressive imager. Metamaterials are engineered materials with properties that are usually unattainable in nature. Acoustic metamaterials can possess highly anisotropy, strongly dispersion, negative dynamic density, or bulk modulus, and they open up new possibilities of wave-matter interaction and signal modulation. In this work, we designed, fabricated, and tested a metamaterial-based single detector, 360 degree field of view compressive acoustic imager. Local resonator arrays are design to resonate randomly in both spatial and spectrum dimensions to favor compressive imaging task. The presented experimental results show that with only about 60 measured values, the imager is able to reconstruct a scene of more than 1000 sampling points in space, achieving a compression ratio of about 20:1. Multiple static and moving target imaging task were performed with this low cost, single detector, non-mechanical scanning compressive imager. Our work paves the way for designing metamaterials based compressive acoustic imaging system. PMID:25235981

Xie, Yangbo; Tsai, Tsung-Han; Brady, David J; Cummer, Steven A

2014-04-01

4

Acoustic Waves in Medical Imaging and Diagnostics  

PubMed Central

Up until about two decades ago acoustic imaging and ultrasound imaging were synonymous. The term “ultrasonography,” or its abbreviated version “sonography” meant an imaging modality based on the use of ultrasonic compressional bulk waves. Since the 1990s numerous acoustic imaging modalities started to emerge based on the use of a different mode of acoustic wave: shear waves. It was demonstrated that imaging with these waves can provide very useful and very different information about the biological tissue being examined. We will discuss physical basis for the differences between these two basic modes of acoustic waves used in medical imaging and analyze the advantages associated with shear acoustic imaging. A comprehensive analysis of the range of acoustic wavelengths, velocities, and frequencies that have been used in different imaging applications will be presented. We will discuss the potential for future shear wave imaging applications. PMID:23643056

Sarvazyan, Armen P.; Urban, Matthew W.; Greenleaf, James F.

2013-01-01

5

Acoustic 3D imaging of dental structures  

SciTech Connect

Our goals for the first year of this three dimensional electodynamic imaging project was to determine how to combine flexible, individual addressable; preprocessing of array source signals; spectral extrapolation or received signals; acoustic tomography codes; and acoustic propagation modeling code. We investigated flexible, individually addressable acoustic array material to find the best match in power, sensitivity and cost and settled on PVDF sheet arrays and 3-1 composite material.

Lewis, D.K. [Lawrence Livermore National Lab., CA (United States); Hume, W.R. [California Univ., Los Angeles, CA (United States); Douglass, G.D. [California Univ., San Francisco, CA (United States)

1997-02-01

6

Acoustic microscopy — Beyond high resolution imaging  

Microsoft Academic Search

There are three major objectives of acoustic microscopy in medicine and biology; 1) rapid examination of histopathology without staining or slicing, 2) search for the origin of echo in clinical ultrasound imaging and 3) novel approach to the pathophysiology from biomechanical point of view. The design of our newest acoustic microscopy is flexible to realize multimode ultrasound microscope with conventional

Yoshifumi Saijo

2009-01-01

7

Ultrafast acoustics for imaging at the nanoscale  

NASA Astrophysics Data System (ADS)

In this paper we present a series of experiments which show that 2-D and possibly 3-D imaging with sub-micron resolution is possible by means of ultrafast acoustic techniques. Optical pulses from a Ti:sapphire laser are used to generate picosecond acoustic pulses on one side of a ~1 mm thick Si wafer. The 1 mm distance is sufficient for the acoustic waves to diffract to the far field before they are detected by time-delayed probe pulses from the Ti:sapphire laser. The acoustic waves are either generated by a surface nanostructure or scattered from a buried nanostructure, and an image of that nanostructure is reconstructed through an analysis of the detected acoustic waves.

Daly, B. C.; Norris, T. B.

2007-12-01

8

Imaging of Acoustic Waves in Sand  

SciTech Connect

There is considerable interest in detecting objects such as landmines shallowly buried in loose earth or sand. Various techniques involving microwave, acoustic, thermal and magnetic sensors have been used to detect such objects. Acoustic and microwave sensors have shown promise, especially if used together. In most cases, the sensor package is scanned over an area to eventually build up an image or map of anomalies. We are proposing an alternate, acoustic method that directly provides an image of acoustic waves in sand or soil, and their interaction with buried objects. The INEEL Laser Ultrasonic Camera utilizes dynamic holography within photorefractive recording materials. This permits one to image and demodulate acoustic waves on surfaces in real time, without scanning. A video image is produced where intensity is directly and linearly proportional to surface motion. Both specular and diffusely reflecting surfaces can be accomodated and surface motion as small as 0.1 nm can be quantitatively detected. This system was used to directly image acoustic surface waves in sand as well as in solid objects. Waves as frequencies of 16 kHz were generated using modified acoustic speakers. These waves were directed through sand toward partially buried objects. The sand container was not on a vibration isolation table, but sat on the lab floor. Interaction of wavefronts with buried objects showed reflection, diffraction and interference effects that could provide clues to location and characteristics of buried objects. Although results are preliminary, success in this effort suggests that this method could be applied to detection of buried landmines or other near-surface items such as pipes and tanks.

Deason, Vance Albert; Telschow, Kenneth Louis; Watson, Scott Marshall

2003-08-01

9

Object Characterization Based on Multispectral Acoustic Imaging  

NASA Astrophysics Data System (ADS)

In previous studies, acoustic imaging was conducted using a single frequency or a limited number of frequencies that were not sufficient to clearly describe and explain the object characteristics. In this study, multispectral acoustic imaging (MSAI) is proposed to reveal rich information of object characteristics. An experimental study on object surfaces is conducted to verify the validity of the technique. Acoustic imaging of object surfaces is performed on the basis of a significant number of spectra over a wide frequency range. Using the frequency-swept irradiation from 1 to 20 kHz at 30 Hz intervals, we demonstrate the visualization of the following three different object surfaces: a rigid surface with small holes with and without a piece of thin paper covering the surface, and a boundary between wood and rubber plates. The distributions of sound pressure reconstructed at each frequency by a near-field acoustic holography (NAH) technique are shown. In multispectral acoustic imaging, frequency dependence provides us rich information about the surface shape and material properties of the objects; thus, the characteristics of the surfaces are successfully visualized.

Guo, Xinhua; Mizuno, Yosuke; Nakamura, Kentaro

2013-12-01

10

Imaging of surface acoustic waves  

Microsoft Academic Search

A new experimental method has been devised that directly determines the group velocities of surface acoustic waves. A point source and a point detector are employed to measure the ultrasonic transmission across a solid surface as a continuous function of the propagation direction. Results for single pulses give the times-of-flight for both Rayleigh surface waves (RSW's) and pseudo-surface-waves (PSW's). Calculations

R. E. Vines; M. R. Hauser; J. P. Wolfe

1995-01-01

11

Acoustic imaging systems (for robotic object acquisition)  

NASA Astrophysics Data System (ADS)

The long-term objective of the effort is to establish successful approaches for 3D acoustic imaging of dense solid objects in air to provide the information required for acquisition and manipulation of these objects by a robotic system. The objective of this first year's work was to achieve and demonstrate the determination of the external geometry (shape) of such objects with a fixed sparse array of sensors, without the aid of geometrical models or extensive training procedures. Conventional approaches for acoustic imaging fall into two basic categories. The first category is used exclusively for dense solid objects. It involves echo-ranging from a large number of sensor positions, achieved either through the use of a larger array of transducers or through extensive physical scanning of a small array. This approach determines the distance to specular reflection points from each sensor position; with suitable processing an image can be inferred. The second category uses the full acoustic waveforms to provide an image, but is strictly applicable only to weak inhomogeneities. The most familiar example is medical imaging of the soft tissue portions of the body where the range of acoustic impedance is relatively small.

Richardson, J. M.; Martin, J. F.; Marsh, K. A.; Schoenwald, J. S.

1985-03-01

12

15 Acoustic Daylight Imaging in the Michael J. Buckingham  

E-print Network

15 Acoustic Daylight Imaging in the Ocean Michael J. Buckingham Scripps Institution of Oceanography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 418 15.4 Acoustic daylight images . . . . . . . . . . . . . . . . . . . . . . . . 420 15.5 Concluding of radiation, including light. Acoustic techniques are thus a pre- ferred choice for probing the ocean depths

Buckingham, Michael

13

Imaging acoustic waves in microscopic wedges  

NASA Astrophysics Data System (ADS)

Using an ultrafast optical technique we image near-gigahertz flexural acoustic waves propagating in a thin gold wedge deposited on an ultrathin silicon nitride slab. Temporal Fourier transforms of the imaged data in two dimensions allow individual frequencies to be accessed. The wave fronts associated with antisymmetric Lamb waves bend towards the thin end of the wedge. This behaviour is mimicked with an analytical model based on sections of a linear wedge. We also conduct numerical simulations which show good agreement with the experimental results.

Tomoda, Motonobu; Matsueda, Shinnosuke; Otsuka, Paul H.; Matsuda, Osamu; Veres, Istvan A.; Gusev, Vitalyi E.; Wright, Oliver B.

2014-10-01

14

Acoustic imaging of subtle porosity variations in ceramics  

NASA Technical Reports Server (NTRS)

Acoustic images of silicon carbide ceramic disks were obtained using a precision scanning contact pulse-echo technique. Phase and cross-correlation velocity and attenuation maps were used to form color images of microstructural variations. These acoustic images reveal microstructural variations not observable with X-radiography.

Generazio, E. R.; Roth, D. J.; Baaklini, G. Y.

1988-01-01

15

Acoustic and Photoacoustic Molecular Imaging of Cancer  

PubMed Central

Ultrasound and combined optical and ultrasonic (photoacoustic) molecular imaging have shown great promise in the visualization and monitoring of cancer through imaging of vascular and extravascular molecular targets. Contrast-enhanced ultrasound with molecularly targeted microbubbles can detect early-stage cancer through the visualization of targets expressed on the angiogenic vasculature of tumors. Ultrasonic molecular imaging can be extended to the imaging of extravascular targets through use of nanoscale, phase-change droplets and photoacoustic imaging, which provides further molecular information on cancer given by the chemical composition of tissues and by targeted nanoparticles that can interact with extravascular tissues at the receptor level. A new generation of targeted contrast agents goes beyond merely increasing imaging signal at the site of target expression but shows activatable and differential contrast depending on their interactions with the tumor microenvironment. These innovations may further improve our ability to detect and characterize tumors. In this review, recent developments in acoustic and photoacoustic molecular imaging of cancer are discussed. PMID:24187042

Wilson, Katheryne E.; Wang, Tzu Yin; Willmann, Jurgen K.

2014-01-01

16

Passive imaging in nondiffuse acoustic wavefields.  

PubMed

A main property of diffuse acoustic wavefields is that, taken any two points, each of them can be seen as the source of waves and the other as the recording station. This property is shown to follow simply from array azimuthal selectivity and Huygens principle in a locally isotropic wavefield. Without time reversal, this property holds approximately also in anisotropic azimuthally uniform wavefields, implying much looser constraints for undistorted passive imaging than those required by a diffuse field. A notable example is the seismic noise field, which is generally nondiffuse, but is found to be compatible with a finite aperture anisotropic uniform wavefield. The theoretical predictions were confirmed by an experiment on seismic noise in the mainland of Venice, Italy. PMID:18518643

Mulargia, Francesco; Castellaro, Silvia

2008-05-30

17

Optimization of a Biometric System Based on Acoustic Images  

PubMed Central

On the basis of an acoustic biometric system that captures 16 acoustic images of a person for 4 frequencies and 4 positions, a study was carried out to improve the performance of the system. On a first stage, an analysis to determine which images provide more information to the system was carried out showing that a set of 12 images allows the system to obtain results that are equivalent to using all of the 16 images. Finally, optimization techniques were used to obtain the set of weights associated with each acoustic image that maximizes the performance of the biometric system. These results improve significantly the performance of the preliminary system, while reducing the time of acquisition and computational burden, since the number of acoustic images was reduced. PMID:24616643

Izquierdo Fuente, Alberto; Del Val Puente, Lara; Villacorta Calvo, Juan J.; Raboso Mateos, Mariano

2014-01-01

18

Laser Acoustic Imaging of Film Bulk Acoustic Resonator (FBAR) Lateral Mode Dispersion  

NASA Astrophysics Data System (ADS)

A laser acoustic imaging microscope has been developed that measures acoustic motion with high spatial resolution without scanning. Images are recorded at normal video frame rates and heterodyne principles are used to allow operation at any frequency from Hz to GHz. Fourier transformation of the acoustic amplitude and phase displacement images provides a direct quantitative determination of excited mode wavenumbers at any frequency. Results are presented at frequencies near the first longitudinal thickness mode (˜ 900 MHz) demonstrating simultaneous excitation of lateral modes with nonzero wavenumbers in an electrically driven AlN thin film acoustic resonator. Images combined at several frequencies form a direct visualization of lateral mode dispersion relations for the device under test allowing mode identification and a direct measure of specific lateral mode properties. Discussion and analysis of the results are presented in comparison with plate wave modeling of these devices taking account for material anisotropy and multilayer films.

Telschow, Ken L.

2005-04-01

19

Laser Acoustic Imaging of Film Bulk Acoustic Resonator (FBAR) Lateral Mode Dispersion  

SciTech Connect

A laser acoustic imaging microscope has been developed that measures acoustic motion with high spatial resolution without scanning. Images are recorded at normal video frame rates and heterodyne principles are used to allow operation at any frequency from Hz to GHz. Fourier transformation of the acoustic amplitude and phase displacement images provides a direct quantitative determination of excited mode wavenumbers at any frequency. Results are presented at frequencies near the first longitudinal thickness mode (~ 900 MHz) demonstrating simultaneous excitation of lateral modes with nonzero wavenumbers in an electrically driven AlN thin film acoustic resonator. Images combined at several frequencies form a direct visualization of lateral mode dispersion relations for the device under test allowing mode identification and a direct measure of specific lateral mode properties. Discussion and analysis of the results are presented in comparison with plate wave modeling of these devices taking account for material anisotropy and multilayer films.

Ken L. Telschow

2004-07-01

20

An experimental acoustic cloak for generating virtual images  

NASA Astrophysics Data System (ADS)

A two-dimensional acoustic cloak is realized to generate virtual image in air. The cloak is designed to make the backscattering characteristics of a quadrangular prism the same as that of a plate based on transformation acoustics. The required anisotropic parameters of the cloak shell are obtained by acoustic metamaterial made of perforated plates, which are easy to fabricate and unitize. The measurements of the backward and near-backward scattering fields confirm the validity of the proposed cloak. Experimental results show the possibility to hide the shape of an object by changing the reflection properties by using transformation acoustics.

Hu, Wenlin; Fan, Yuxian; Ji, Peifeng; Yang, Jun

2013-01-01

21

3D acoustic imaging applied to the Baikal Neutrino Telescope  

E-print Network

A hydro-acoustic imaging system was tested in a pilot study on distant localization of elements of the Baikal underwater neutrino telescope. For this innovative approach, based on broad band acoustic echo signals and strictly avoiding any active acoustic elements on the telescope, the imaging system was temporarily installed just below the ice surface, while the telescope stayed in its standard position at 1100 m depth. The system comprised an antenna with four acoustic projectors positioned at the corners of a 50 meter square; acoustic pulses were "linear sweep-spread signals" - multiple-modulated wide-band signals (10-22 kHz) of 51.2 s duration. Three large objects (two string buoys and the central electronics module) were localized by the 3D acoustic imaging, with a accuracy of ~0.2 m (along the beam) and ~1.0 m (transverse). We discuss signal forms and parameters necessary for improved 3D acoustic imaging of the telescope, and suggest a layout of a possible stationary bottom based 3D imaging setup. The presented technique may be of interest for neutrino telescopes of km3-scale and beyond, as a flexible temporary or as a stationary tool to localize basic telescope elements, while these are completely passive.

K. G. Kebkal; R. Bannasch; O. G. Kebkal; A. I. Panfilov; R. Wischnewski

2008-11-07

22

Acoustic Radiation Force Elasticity Imaging in Diagnostic Ultrasound  

PubMed Central

The development of ultrasound-based elasticity imaging methods has been the focus of intense research activity since the mid-1990s. In characterizing the mechanical properties of soft tissues, these techniques image an entirely new subset of tissue properties that cannot be derived with conventional ultrasound techniques. Clinically, tissue elasticity is known to be associated with pathological condition and with the ability to image these features in vivo, elasticity imaging methods may prove to be invaluable tools for the diagnosis and/or monitoring of disease. This review focuses on ultrasound-based elasticity imaging methods that generate an acoustic radiation force to induce tissue displacements. These methods can be performed non-invasively during routine exams to provide either qualitative or quantitative metrics of tissue elasticity. A brief overview of soft tissue mechanics relevant to elasticity imaging is provided, including a derivation of acoustic radiation force, and an overview of the various acoustic radiation force elasticity imaging methods. PMID:23549529

Doherty, Joshua R.; Trahey, Gregg E.; Nightingale, Kathryn R.; Palmeri, Mark L.

2013-01-01

23

Acoustic imaging in a water filled metallic pipe  

SciTech Connect

A method is described for the imaging of the interior of a water filled metallic pipe using acoustical techniques. The apparatus consists of an array of 20 acoustic transducers mounted circumferentially around the pipe. Each transducer is pulsed in sequence, and the echos resulting from bubbles in the interior are digitized and processed by a computer to generate an image. The electronic control and digitizing system and the software processing of the echo signals are described. The performance of the apparatus is illustrated by the imaging of simulated bubbles consisting of thin walled glass spheres suspended in the pipe.

Kolbe, W.F.; Turko, B.T.; Leskovar, B.

1984-04-01

24

Assessing the variability in respiratory acoustic thoracic imaging (RATHI).  

PubMed

Multichannel analysis of lung sounds (LSs) has enabled the generation of a functional image for the temporal and spatial study of LS intensities in healthy and diseased subjects; this method is known as respiratory acoustic thoracic imaging (RATHI). This acoustic imaging technique has been applied to diverse pulmonary conditions, but it is important to contribute to the understanding of RATHI characteristics, such as acoustic spatial distribution, dependence on airflow and variability. The purpose of the current study is to assess the intra-subject and inter-subject RATHI variabilities in a cohort of 12 healthy male subjects (24.3±1.5 years) using diverse quantitative indices. The indices were obtained directly from the acoustic image and did not require scores from human raters, which helps to prevent inter-observer variability. To generate the acoustic image, LSs were acquired at 25 positions on the posterior thoracic surface by means of airborne sound sensors with a wide frequency band from 75 up to 1000 Hz under controlled airflow conditions at 1.0, 1.5 and 2.0 L/s. To assess intra-subject variability, the degree of similitude between inspiratory acoustic images was evaluated through quadratic mutual information based on the Cauchy-Schwartz inequality (I(CS)). The inter-subject variability was assessed by an image registration procedure between RATHIs and X-ray images to allow the computation of average and variance acoustic image in the same coordinate space. The results indicated that intra-subject RATHI similitude, reflected by I(CS-global), averaged 0.960±0.008, 0.958±0.008 and 0.960±0.007 for airflows of 1.0, 1.5, and 2L/s, respectively. As for the inter-subject variability, the variance image values for three airflow conditions indicated low image variability as they ranged from 0.01 to 0.04. In conclusion, the assessment of intra-subject and inter-subject variability by similitude indices indicated that the acoustic image pattern is repeatable along different respiratory cycles and across different subjects. Therefore, RATHI could be used to explore different aspects of spatial distribution and its association with regional pulmonary ventilation. PMID:24480164

Charleston-Villalobos, S; Torres-Jiménez, A; González-Camarena, R; Chi-Lem, G; Aljama-Corrales, T

2014-02-01

25

Acoustic Radiation Force Impulse (ARFI) Imaging: a Review  

PubMed Central

Acoustic radiation force based elasticity imaging methods are under investigation by many groups. These methods differ from traditional ultrasonic elasticity imaging methods in that they do not require compression of the transducer, and are thus expected to be less operator dependent. Methods have been developed that utilize impulsive (i.e. < 1 ms), harmonic (pulsed), and steady state radiation force excitations. The work discussed herein utilizes impulsive methods, for which two imaging approaches have been pursued: 1) monitoring the tissue response within the radiation force region of excitation (ROE) and generating images of relative differences in tissue stiffness (Acoustic Radiation Force Impulse (ARFI) imaging); and 2) monitoring the speed of shear wave propagation away from the ROE to quantify tissue stiffness (Shear Wave Elasticity Imaging (SWEI)). For these methods, a single ultrasound transducer on a commercial ultrasound system can be used to both generate acoustic radiation force in tissue, and to monitor the tissue displacement response. The response of tissue to this transient excitation is complicated and depends upon tissue geometry, radiation force field geometry, and tissue mechanical and acoustic properties. Higher shear wave speeds and smaller displacements are associated with stiffer tissues, and slower shear wave speeds and larger displacements occur with more compliant tissues. ARFI images have spatial resolution comparable to that of B-mode, often with greater contrast, providing matched, adjunctive information. SWEI images provide quantitative information about the tissue stiffness, typically with lower spatial resolution. A review these methods and examples of clinical applications are presented herein. PMID:22545033

Nightingale, Kathy

2012-01-01

26

Holographic imaging of surface acoustic waves Francois Bruno,1  

E-print Network

phase mod- ulation has been extensively used to measure vibrations in nondestructive testingHolographic imaging of surface acoustic waves Fran¸cois Bruno,1 J´er^ome Laurent,1 Daniel Royer,1-tunable time-averaged laser Doppler holographic imaging scheme on a sensor array, at video-rate. This method

27

Quantitative Determination of Lateral Mode Dispersion in Film Bulk Acoustic Resonators through Laser Acoustic Imaging  

SciTech Connect

Film Bulk Acoustic Resonators are useful for many signal processing applications. Detailed knowledge of their operation properties are needed to optimize their design for specific applications. The finite size of these resonators precludes their use in single acoustic modes; rather, multiple wave modes, such as, lateral wave modes are always excited concurrently. In order to determine the contributions of these modes, we have been using a newly developed full-field laser acoustic imaging approach to directly measure their amplitude and phase throughout the resonator. This paper describes new results comparing modeling of both elastic and piezoelectric effects in the active material with imaging measurement of all excited modes. Fourier transformation of the acoustic amplitude and phase displacement images provides a quantitative determination of excited mode amplitude and wavenumber at any frequency. Images combined at several frequencies form a direct visualization of lateral mode excitation and dispersion for the device under test allowing mode identification and comparison with predicted operational properties. Discussion and analysis are presented for modes near the first longitudinal thickness resonance (~900 MHz) in an AlN thin film resonator. Plate wave modeling, taking account of material crystalline orientation, elastic and piezoelectric properties and overlayer metallic films, will be discussed in relation to direct image measurements.

Ken Telschow; John D. Larson III

2006-10-01

28

Synthetic aperture acoustic imaging of non-metallic cords  

NASA Astrophysics Data System (ADS)

This work presents a set of measurements collected with a research prototype synthetic aperture acoustic (SAA) imaging system. SAA imaging is an emerging technique that can serve as an inexpensive alternative or logical complement to synthetic aperture radar (SAR). The SAA imaging system uses an acoustic transceiver (speaker and microphone) to project acoustic radiation and record backscatter from a scene. The backscattered acoustic energy is used to generate information about the location, morphology, and mechanical properties of various objects. SAA detection has a potential advantage when compared to SAR in that non-metallic objects are not readily detectable with SAR. To demonstrate basic capability of the approach with non-metallic objects, targets are placed in a simple, featureless scene. Nylon cords of five diameters, ranging from 2 to 15 mm, and a joined pair of 3 mm fiber optic cables are placed in various configurations on flat asphalt that is free of clutter. The measurements were made using a chirp with a bandwidth of 2-15 kHz. The recorded signal is reconstructed to form a two-dimensional image of the distribution of acoustic scatterers within the scene. The goal of this study was to identify basic detectability characteristics for a range of sizes and configurations of non-metallic cord. It is shown that for sufficiently small angles relative to the transceiver path, the SAA approach creates adequate backscatter for detectability.

Glean, Aldo A. J.; Good, Chelsea E.; Vignola, Joseph F.; Judge, John A.; Ryan, Teresa J.; Bishop, Steven S.; Gugino, Peter M.; Soumekh, Mehrdad

2012-06-01

29

Laser Imaging of Airborne Acoustic Emission by Nonlinear Defects  

NASA Astrophysics Data System (ADS)

Strongly nonlinear vibrations of near-surface fractured defects driven by an elastic wave radiate acoustic energy into adjacent air in a wide frequency range. The variations of pressure in the emitted airborne waves change the refractive index of air thus providing an acoustooptic interaction with a collimated laser beam. Such an air-coupled vibrometry (ACV) is proposed for detecting and imaging of acoustic radiation of nonlinear spectral components by cracked defects. The photoelastic relation in air is used to derive induced phase modulation of laser light in the heterodyne interferometer setup. The sensitivity of the scanning ACV to different spatial components of the acoustic radiation is analyzed. The animated airborne emission patterns are visualized for the higher harmonic and frequency mixing fields radiated by planar defects. The results confirm a high localization of the nonlinear acoustic emission around the defects and complicated directivity patterns appreciably different from those observed for fundamental frequencies.

Solodov, Igor; Döring, Daniel; Busse, Gerd

2008-06-01

30

Acoustic angiography: a new imaging modality for assessing microvasculature architecture.  

PubMed

The purpose of this paper is to provide the biomedical imaging community with details of a new high resolution contrast imaging approach referred to as "acoustic angiography." Through the use of dual-frequency ultrasound transducer technology, images acquired with this approach possess both high resolution and a high contrast-to-tissue ratio, which enables the visualization of microvascular architecture without significant contribution from background tissues. Additionally, volumetric vessel-tissue integration can be visualized by using b-mode overlays acquired with the same probe. We present a brief technical overview of how the images are acquired, followed by several examples of images of both healthy and diseased tissue volumes. 3D images from alternate modalities often used in preclinical imaging, contrast-enhanced micro-CT and photoacoustics, are also included to provide a perspective on how acoustic angiography has qualitatively similar capabilities to these other techniques. These preliminary images provide visually compelling evidence to suggest that acoustic angiography may serve as a powerful new tool in preclinical and future clinical imaging. PMID:23997762

Gessner, Ryan C; Frederick, C Brandon; Foster, F Stuart; Dayton, Paul A

2013-01-01

31

Segmentation of acoustic images by neural network processing  

NASA Astrophysics Data System (ADS)

A segmentation method for biomedical acoustic images is reported which efficiently classifies the groups of similar image elements (pixels) and separates them into particular characteristic regions. As the input data, the method uses the pixel intensities of the source image. The classification is performed by learning vector quantization neural networks, which separate the main classes (structures, tissues, artifacts, etc.) present in the image. Because this type of neural network implies that the number of the classes is known and that the network should be trained by instruction, an expert must participate in the process of generating the input data. Results obtained by processing test acoustic (ultrasonic) images demonstrate that the method is capable of effectively solving sonography classification problems. The accuracy of the method is estimated by comparison with the segmentation performed manually.

Il'in, S. V.; Rychagov, M. N.

2004-09-01

32

Acoustic Molecular Imaging and Targeted Drug Delivery with Perfluorocarbon Nanoparticles  

NASA Astrophysics Data System (ADS)

Advances in molecular biology and cellular biochemistry are providing new opportunities for diagnostic medical imaging to "see" beyond the anatomical manifestations of disease to the earliest biochemical signatures of disease. Liquid perfluorocarbon nanoparticles provide inherent acoustic contrast when bound to targets, e.g., fibrin deposits in a thrombus, but unbound nanoparticles are undetectable. This nanoparticle platform may be further functionalized with paramagnetic metals, such as gadolinium, or radionuclides, with homing ligands, like anti-?v?3-integrins, and therapeutic agents. Acoustic imaging of densely distributed biomarkers, e.g., fibrin epitopes, is readily accommodated with fundamental imaging, but for sparse biomarkers, e.g., integrins, we have developed and implemented novel, nonlinear imaging techniques based upon information-theoretic receivers (i.e., thermodynamic receivers). These novel receivers allow sensitive direct imaging of contrast development.

Lanza, Gregory M.; Hughes, Michael. S.; Marsh, Jon N.; Scott, Michael J.; Zhang, Huiying; Lacy, Elizabeth K.; Allen, John S.; Wickline, Samuel A.

2005-03-01

33

Acoustic-resolution photoacoustic imaging system with simple fiber illumination  

NASA Astrophysics Data System (ADS)

Acoustic-resolution photoacoustic microscopy (AR-PAM) with dark-field confocal illumination enables unique high-resolution visualization of chromophores in tissue, such as microvasculatures, within depths of a few millimeters. However, most current systems are bulky and use complex optical components for illumination, thus requiring highly sensitive alignment. In this study, we developed a compact alignment-free acoustic-resolution photoacoustic imaging system with simple fiber illumination. Four optical fibers were placed in four directions around a high-frequency (30-MHz) ultrasound sensor attached with the high-numerical-aperture acoustic lens. The setting angle of the fibers were determined to form a dark field on the tissue surface under the acoustic lens and for the four light beams from the fibers to be combined near the focal point of the acoustic lens, i.e., at a depth of around 1.2 mm in the tissue. The acoustic lens and output ends of the fibers were capped with an acoustically and optically transparent engineering plastic sheet, whose surface can be directly placed and scanned on the tissue surface with ultrasound gel. The diameter and height of this imaging head were as small as 32 mm and 27 mm respectively. The phantom study showed that the lateral signal spreading was 120 ?m, which agreed well with the theoretical value of 112 ?m. With the system, we attempted to image vasculatures in the rat skin, demonstrating high-contrast visualization of the blood vessels of a few hundred micrometers in diameter in the tissue.

Tsunoi, Yasuyuki; Sato, Shunichi; Watanabe, Ryota; Kawauchi, Satoko; Ashida, Hiroshi; Terakawa, Mitsuhiro

2013-03-01

34

Breast imaging with acoustic tomography: a comparative study with MRI  

NASA Astrophysics Data System (ADS)

The objective of this study is to investigate a potential low-cost-alternative to MRI, based on acoustic tomography. Using MRI as the gold standard, our goals are to assess the performance of acoustic tomography in (i) depicting normal breast anatomy, (ii) imaging cancerous lesions and (iii) accentuating lesions relative to background tissue using thresholding techniques. Fifteen patients were imaged with MRI and with an acoustic tomography prototype. A qualitative visual comparison of the MRI and prototype images was used to verify anatomical similarities. These similarities suggest that the prototype can image fibrous stroma, parenchyma and fatty tissues, with similar sensitivity to MRI. The prototype was also shown to be able to image masses but equivalency in mass sensitivity with MRI could not be established because of the small numbers of patients and the prototype's limited scanning range. The range of thresholds required to establish tumor volume equivalency suggests that a universal threshold for isolating masses relative to background tissue is possible with acoustic tomography. Thresholding techniques promise to accentuate masses relative to background anatomy which may prove clinically useful in potential screening applications. Future work will utilize larger trials to verify these preliminary conclusions.

Ranger, Bryan; Littrup, Peter; Duric, Neb; Li, Cuiping; Lupinacci, Jessica; Myc, Lukasz; Rama, Olsi; Bey-Knight, Lisa

2009-02-01

35

Acoustic imaging of underground storage tank wastes  

SciTech Connect

Acoustics is a potential tool to determine the properties of high level wastes stored in Underground Storage Tanks. Some acoustic properties were successfully measured by a limited demonstration conducted in 114-TX. This accomplishment provides the basis for expanded efforts to qualify techniques which depend on the acoustic properties of tank wastes. This work is being sponsored by the Department of Energy under the Office of Science and Technology. In FY-1994, limited Tank Waste Remediation Systems EM-30 support was available at Hanford and Los Alamos National Laboratory. The Massachusetts Institute of Technology (MIT) and Earth Resources Laboratory (ERL) were engaged for analysis support, and Elohi Geophysics, Inc. for seismic testing services. Westinghouse-Hanford Company provided the testing and training, supplied the special engineering and safety analysis equipment and procedures, and provided the trained operators for the actual tank operations. On 11/9/94, limited in-tank tests were successfully conducted in tank 114-TX. This stabilized Single Shell Tank was reported as containing 16.8 feet of waste, the lower 6.28 feet of which contained interstitial liquid. Testing was conducted over the lower 12 feet, between two Liquid Observation Wells thirty feet apart. The ``quick-look`` data was reviewed on-site by MIT and Elohi.

Mech, S.J.

1995-09-01

36

COMBINED PHOTO-ACOUSTIC AND ACOUSTIC IMAGING OF HUMAN BREAST SPECIMENS IN THE MAMMOGRAPHIC GEOMETRY  

PubMed Central

A photo-acoustic volume imaging (PAVI) system was designed to study breast cancer detection and diagnosis in the mammographic geometry in combination with automated 3-D ultrasound (AUS). The goal of the work described here was to validate the design and evaluate its performance in human breast tissues for non-invasive imaging of deeply positioned structures covering such geometry. The good penetration of nearinfrared light and high receiving sensitivity of a broad-bandwidth, 572-element, 2-D poly(vinyl difluoride) array at a low center frequency of 1 MHz were used with 20 channel simultaneous acquisition. Pseudo-lesions filled with dilute blood were imaged in three human breast specimens at various depths up to 49 mm. With near-infrared light illumination and 256-sample averaging, the extrapolated maximum depth in imaging a 2.4-mm blood-rich lesion with a 3-dB contrast-to-noise ratio in a compressed breast was 54 mm. Three-dimensional photo-acoustic volume image stacks of the breasts were co-registered with 3-D ultrasound image stacks, suggesting for the first time that PAVI, based on the intrinsic tissue contrast, can visualize tissue interfaces other than those with blood, including the inner skin surface and connective tissue sheets. With the designed system, PAVI revealed satisfactory imaging depth and sensitivity for coverage of the entire breast when imaged from both sides in the mammographic geometry with mild compression. PMID:23972486

Xie, Zhixing; Hooi, Fong Ming; Fowlkes, J Brian; Pinsky, Renee W.; Wang, Xueding; Carson, Paul L.

2013-01-01

37

Acoustic Imaging in 3D Frank Natterer  

E-print Network

of other imaging techniques such as CT or MRI. Recently, great efforts have been made to produce ultrasound images of higher quality. Scanners for ultrasound mammography have been developed by TechniScan in Salt Lake City and Karmanos Cancer Research in Detroit. These scanners produce high quality pictures

Münster, Westfälische Wilhelms-Universität

38

Randomized comparison of coronary angiography using 4F catheters: 4F manual versus "Acisted" power injection technique.  

PubMed

Compared with 6F catheters, diagnostic coronary angiographic and ventriculographic images with 4F catheters can be obtained with equivalent results using less radiographic contrast volume. Whether 4F coronary angiography would be superior using a power-assisted, operator-controlled technique compared with manual technique is unknown. To determine whether 4F coronary angiography using operator-controlled power injection (Acist, Minneapolis, MN) was equivalent or superior to the 4F manual technique, 96 unselected patients undergoing transfemoral coronary angiography were randomized to 4F catheter using a power injection or manual technique. Procedural characteristics and angiographic quality scores were analyzed. Comparing the 4F manual with the 4F power-injection technique, coronary angiographic quality scores were equivalent (left coronary artery 4.7 +/- 0.5 vs. 4.7 +/- 0.6, P = 0.99; right coronary artery 4.94 +/- 0.2 vs. 4.88 +/- 0.1, P = 0.21). Left ventriculography scores were lower in 4F Acist with similar contrast volumes. The total study contrast volume was significantly less in the 4F Acist group (119 +/- 35 vs. 149 +/- 49 ml, P = 0.001). Compared with the 4F manual contrast injection technique, diagnostic angiography through 4F catheters with power contrast injection resulted in equivalent coronary angiographic image quality with significantly less radiographic contrast volume. PMID:11387608

Chahoud, G; Khoukaz, S; El-Shafei, A; Azrak, E; Bitar, S; Kern, M J

2001-06-01

39

Designable hybrid sonic crystals for transportation and division of acoustic images  

NASA Astrophysics Data System (ADS)

Conventional sonic crystal (SC) imaging devices can focus acoustic waves from an input source into only one image but not multi-images. Furthermore, the position of formed image cannot be designed at will. In this paper, we propose the hybrid SC imaging devices to achieve multi-images from one-source input along with the designable image positions. The proposed hybrid devices can image acoustic waves radiated both from point source and Gaussian beam, which is different from conventional SC imaging devices that only applies to point source. The multi-functional hybrid sonic crystal will have extensive application in the manipulation of acoustic images.

He, Zhaojian; Deng, Ke; Zhao, Heping; Li, Xiaochun

2012-12-01

40

Vector Acoustics, Vector Sensors, and 3D Underwater Imaging  

NASA Astrophysics Data System (ADS)

Vector acoustic data has two more dimensions of information than pressure data and may allow for 3D underwater imaging with much less data than with hydrophone data. The vector acoustic sensors measures the particle motions due to passing sound waves and, in conjunction with a collocated hydrophone, the direction of travel of the sound waves. When using a controlled source with known source and sensor locations, the reflection points of the sound field can be determined with a simple trigonometric calculation. I demonstrate this concept with an experiment that used an accelerometer based vector acoustic sensor in a water tank with a short-pulse source and passive scattering targets. The sensor consists of a three-axis accelerometer and a matched hydrophone. The sound source was a standard transducer driven by a short 7 kHz pulse. The sensor was suspended in a fixed location and the hydrophone was moved about the tank by a robotic arm to insonify the tank from many locations. Several floats were placed in the tank as acoustic targets at diagonal ranges of approximately one meter. The accelerometer data show the direct source wave as well as the target scattered waves and reflections from the nearby water surface, tank bottom and sides. Without resorting to the usual methods of seismic imaging, which in this case is only two dimensional and relied entirely on the use of a synthetic source aperture, the two targets, the tank walls, the tank bottom, and the water surface were imaged. A directional ambiguity inherent to vector sensors is removed by using collocated hydrophone data. Although this experiment was in a very simple environment, it suggests that 3-D seismic surveys may be achieved with vector sensors using the same logistics as a 2-D survey that uses conventional hydrophones. This work was supported by the Office of Naval Research, program element 61153N.

Lindwall, D.

2007-12-01

41

Subwavelength imaging through spoof surface acoustic waves on a two-dimensional structured rigid surface  

NASA Astrophysics Data System (ADS)

We demonstrate that acoustic subwavelength imaging can be realized through the spoof surface acoustic waves on the surface phononic crystal which is composed of borehole arrays with square lattice in a rigid plate. The dispersion property of the spoof surface acoustic waves on the two-dimensional textured rigid plate is analyzed theoretically. By utilizing the broad flat equifrequency contour of the spoof surface acoustic waves, a subwavelength image with full width at half maximum of 0.14 ? has been obtained both numerically and experimentally. We believe that such work can bring potential applications in the design of acoustic imaging and focusing devices.

Jia, Han; Lu, Minghui; Wang, Qingcui; Bao, Ming; Li, Xiaodong

2013-09-01

42

Identifying Vulnerable Plaques with Acoustic Radiation Force Impulse Imaging  

NASA Astrophysics Data System (ADS)

The rupture of arterial plaques is the most common cause of ischemic complications including stroke, the fourth leading cause of death and number one cause of long term disability in the United States. Unfortunately, because conventional diagnostic tools fail to identify plaques that confer the highest risk, often a disabling stroke and/or sudden death is the first sign of disease. A diagnostic method capable of characterizing plaque vulnerability would likely enhance the predictive ability and ultimately the treatment of stroke before the onset of clinical events. This dissertation evaluates the hypothesis that Acoustic Radiation Force Impulse (ARFI) imaging can noninvasively identify lipid regions, that have been shown to increase a plaque's propensity to rupture, within carotid artery plaques in vivo. The work detailed herein describes development efforts and results from simulations and experiments that were performed to evaluate this hypothesis. To first demonstrate feasibility and evaluate potential safety concerns, finite- element method simulations are used to model the response of carotid artery plaques to an acoustic radiation force excitation. Lipid pool visualization is shown to vary as a function of lipid pool geometry and stiffness. A comparison of the resulting Von Mises stresses indicates that stresses induced by an ARFI excitation are three orders of magnitude lower than those induced by blood pressure. This thesis also presents the development of a novel pulse inversion harmonic tracking method to reduce clutter-imposed errors in ultrasound-based tissue displacement estimates. This method is validated in phantoms and was found to reduce bias and jitter displacement errors for a marked improvement in image quality in vivo. Lastly, this dissertation presents results from a preliminary in vivo study that compares ARFI imaging derived plaque stiffness with spatially registered composition determined by a Magnetic Resonance Imaging (MRI) gold standard in human carotid artery plaques. It is shown in this capstone experiment that lipid filled regions in MRI correspond to areas of increased displacement in ARFI imaging while calcium and loose matrix components in MRI correspond to uniformly low displacements in ARFI imaging. This dissertation provides evidence to support that ARFI imaging may provide important prognostic and diagnostic information regarding stroke risk via measurements of plaque stiffness. More generally, the results have important implications for all acoustic radiation force based imaging methods used clinically.

Doherty, Joshua Ryan

43

Micro-nondestructive evaluation of microelectronics using three-dimensional acoustic imaging  

NASA Astrophysics Data System (ADS)

Holographic-like three-dimensional (3D) acoustic imaging is developed for micro-nondestructive evaluation of microelectronics. It is implemented by stacking all the interface slices together to locate and identify hidden defects. Matching pursuit based acoustic time-frequency domain imaging is proposed to overcome the wavelength limit of axial resolution so that ultra-thin slices are generated. Experiments are performed on 3D acoustic data collected from microelectronic packages. Results show that the proposed technique resolves closely spaced features that are unavailable by conventional acoustic imaging, revealing more image details of defects.

Zhang, Guang-Ming; Harvey, David M.; Burton, David R.

2011-02-01

44

Frequency spectrum spatially resolved acoustic spectroscopy for microstructure imaging  

NASA Astrophysics Data System (ADS)

The microstructure of a material influences the characteristics of a component such as its strength and stiffness. A previously described laser ultrasonic technique known as spatially resolved acoustic spectroscopy (SRAS) can image surface microstructure, using the local surface acoustic wave (SAW) velocity as a contrast mechanism. The technique is robust and tolerant of acoustic aberrations. Compared to other existing methods such as electron backscattered diffraction, SRAS is completely non-contact, non-destructive (as samples do not need to be polished and sectioned), fast, and is capable of inspecting very large components. The SAW velocity, propagating in multiple directions, can in theory be used to determine the crystallographic orientation of grains. SRAS can be implemented by using a fixed grating period with a broadband laser excitation source; the velocity is determined by analysing the measured frequency spectrum. Experimental results acquired using this "frequency spectrum SRAS" (f-SRAS) method are presented. The instrumentation has been improved such that velocity data can be acquired at 1000 points per second. The results are illustrated as velocity maps of material microstructure in two orthogonal directions. We compare velocities measured in multiple propagation direction with those predicted by the numerical model, for several cubic crystals of known orientations.

Li, Wenqi; Sharples, Steve D.; Clark, Matt; Somekh, Michael G.

2011-01-01

45

Designable hybrid sonic crystals for transportation and division of acoustic images  

E-print Network

Conventional sonic crystal (SC) devices designed for acoustic imaging can focus acoustic waves from an input source into only one image but not multi-images. Furthermore the output position of formed image cannot be designed at will. In this paper, we propose the hybrid SC imaging devices to achieve multi-images from one-source-input along with the designable image-positions. The proposed hybrid devices can image acoustic waves radiated both from point source and Gaussian beam, which different from conventional SC imaging devices that only applies to point source. These multi-functional but still simple and easy-to-fabricate devices are believed to find extensive applications, particularly in ultrasonic photography and compact acoustic imaging.

He, Zhaojian; Zhao, Heping; Li, Xiaochun

2012-01-01

46

Feasibility of High Frequency Acoustic Imaging for Inspection of Containments  

SciTech Connect

The Nuclear Regulatory Commission has a program at the Oak Ridge National Laboratory to provide assistance in their assessment of the effects of potential degradation on the structural integrity and Ieaktightness of metal containment vessels and steel liners of concrete containment in nuclear power plants. One of the program objectives is to identify a technique(s) for inspection of inaccessible portions of the containment pressure boundary. Acoustic imaging has been identified as one of these potential techniques. A numerical feasibility study investigated the use of high-frequency bistatic acoustic imaging techniques for inspection of inaccessible portions of the metallic pressure boundary of nuclear power plant containment. The range-dependent version of the OASES Code developed at the Massachusetts Institute of Technology was utilized to perform a series of numerical simulations. OASES is a well developed and extensively tested code for evaluation of the acoustic field in a system of stratified fluid and/or elastic layers. Using the code, an arbitrary number of fluid or solid elastic layers are interleaved, with the outer layers modeled as halfspaces. High frequency vibrational sources were modeled to simulate elastic waves in the steel. The received field due to an arbitrary source array can be calculated at arbitrary depth and range positions. In this numerical study, waves that reflect and scatter from surface roughness caused by modeled degradations (e.g., corrosion) are detected and used to identify and map the steel degradation. Variables in the numerical study included frequency, flaw size, interrogation distance, and sensor incident angle.Based on these analytical simulations, it is considered unlikely that acoustic imaging technology can be used to investigate embedded steel liners of reinforced concrete containment. The thin steel liner and high signal losses to the concrete make this application difficult. Results for portions of steel containment embedded in concrete are more encouraging in that they indicate that the intrinsic backscatter from degradations representing thickness reductions from 10 to 80% the shell thickness are sufficient to permit detection. It is recommended that a controlled experimental program be conducted in which sensor levels are calibrated against degradations to determine if current sensor technology can input sufficient power into the system to provide return levels within the dynamic range of the receivers.

C.N. Corrado; J.E. Bondaryk; V. Godino

1998-08-01

47

Multi-crack imaging using nonclassical nonlinear acoustic method  

NASA Astrophysics Data System (ADS)

Solid materials with cracks exhibit the nonclassical nonlinear acoustical behavior. The micro-defects in solid materials can be detected by nonlinear elastic wave spectroscopy (NEWS) method with a time-reversal (TR) mirror. While defects lie in viscoelastic solid material with different distances from one another, the nonlinear and hysteretic stress—strain relation is established with Preisach—Mayergoyz (PM) model in crack zone. Pulse inversion (PI) and TR methods are used in numerical simulation and defect locations can be determined from images obtained by the maximum value. Since false-positive defects might appear and degrade the imaging when the defects are located quite closely, the maximum value imaging with a time window is introduced to analyze how defects affect each other and how the fake one occurs. Furthermore, NEWS-TR-NEWS method is put forward to improve NEWS-TR scheme, with another forward propagation (NEWS) added to the existing phases (NEWS and TR). In the added phase, scanner locations are determined by locations of all defects imaged in previous phases, so that whether an imaged defect is real can be deduced. NEWS-TR-NEWS method is proved to be effective to distinguish real defects from the false-positive ones. Moreover, it is also helpful to detect the crack that is weaker than others during imaging procedure.

Zhang, Lue; Zhang, Ying; Liu, Xiao-Zhou; Gong, Xiu-Fen

2014-10-01

48

Object detection and imaging with acoustic time reversal mirrors  

NASA Astrophysics Data System (ADS)

Focusing an acoustic wave on an object of unknown shape through an inhomogeneous medium of any geometrical shape is a challenge in underground detection. Optimal detection and imaging of objects needs the development of such focusing techniques. The use of a time reversal mirror (TRM) represents an original solution to this problem. It realizes in real time a focusing process matched to the object shape, to the geometries of the acoustic interfaces and to the geometries of the mirror. It is a self adaptative technique which compensates for any geometrical distortions of the mirror structure as well as for diffraction and refraction effects through the interfaces. Two real time 64 and 128 channel prototypes have been built in our laboratory and TRM experiments demonstrating the TRM performance through inhomogeneous solid and liquid media are presented. Applications to medical therapy (kidney stone detection and destruction) and to nondestructive testing of metallurgical samples of different geometries are described. Extension of this study to underground detection and imaging will be discussed.

Fink, Mathias

1993-11-01

49

From Acoustic Segmentation to Language Processing: Evidence from Optical Imaging  

PubMed Central

During language acquisition in infancy and when learning a foreign language, the segmentation of the auditory stream into words and phrases is a complex process. Intuitively, learners use “anchors” to segment the acoustic speech stream into meaningful units like words and phrases. Regularities on a segmental (e.g., phonological) or suprasegmental (e.g., prosodic) level can provide such anchors. Regarding the neuronal processing of these two kinds of linguistic cues a left-hemispheric dominance for segmental and a right-hemispheric bias for suprasegmental information has been reported in adults. Though lateralization is common in a number of higher cognitive functions, its prominence in language may also be a key to understanding the rapid emergence of the language network in infants and the ease at which we master our language in adulthood. One question here is whether the hemispheric lateralization is driven by linguistic input per se or whether non-linguistic, especially acoustic factors, “guide” the lateralization process. Methodologically, functional magnetic resonance imaging provides unsurpassed anatomical detail for such an enquiry. However, instrumental noise, experimental constraints and interference with EEG assessment limit its applicability, pointedly in infants and also when investigating the link between auditory and linguistic processing. Optical methods have the potential to fill this gap. Here we review a number of recent studies using optical imaging to investigate hemispheric differences during segmentation and basic auditory feature analysis in language development. PMID:20725516

Obrig, Hellmuth; Rossi, Sonja; Telkemeyer, Silke; Wartenburger, Isabell

2010-01-01

50

Acoustical Imaging, Volume 26 edited by Roman Gr. Maev, University of Windsor, Ontario, Canada  

E-print Network

Ultrasound with New Reconstruction Algorithms for Breast Imaging; P.J. Littrup, et al. Part 3: Acoustic of Breast Cancer Using Ultrasonic Echography; I. Akiyama, et al. Ultrasonic Images of Tissue Local Power Allograft Rejection by Acoustic Microscopy; Y. Saijo, et al. Ultrasonic Measurement of Depth

Wagner, Oliver

51

NEW GENERATION OF HIGH RESOLUTION ACOUSTIC IMAGING TECHNIQUE FOR MATERIAL CHARACTERIZATION AND NDT  

Microsoft Academic Search

This paper deals with the analysis of the novel high-resolution acoustic imaging NDE methods and technique for inspection the internal structure of the various materials and products, including different metals, alloys, composites, ceramics, multilayer structured materials, polymer blends, various joints, etc. The theoretical bases, as well as experimental fundamentals for quantitative characterization of the contrast response in the acoustic imaging

R. Gr

2006-01-01

52

Acoustic imaging of underground storage tank wastes: A feasibility study. Final report  

Microsoft Academic Search

The objectives for this underground storage tank (UST) imaging investigation are: (1) to assess the feasibility of using acoustic methods in UST wastes, if shown to be feasible, develop and assess imaging strategies; (2) to assess the validity of using chemical simulants for the development of acoustic methods and equipment. This investigation examined the velocity of surrogates, both salt cake

R. Turpening; Z. Zhu; C. Caravana; J. Matarese; W. Turpening

1995-01-01

53

Acoustic streaming in lithotripsy fields: preliminary observation using a particle image velocimetry method  

Microsoft Academic Search

This study considers the acoustic streaming in water produced by a lithotripsy pulse. Particle image velocimetry (PIV) method was employed to visualize the acoustic streaming produced by an electromagnetic shock wave generator using video images of the light scattering particles suspended in water. Visualized streaming features including several local peaks and vortexes around or at the beam focus were easily

Min Joo Choi; Doeg Hee Doh; Tae Gyu Hwang; Chu Hyun Cho; Dong Guk Paeng; Gun Hee Rim; A. J. Coleman

2006-01-01

54

Acoustic 3-D Imaging Unveils Swimming Behavior of Microscopic Ocean Plankton  

NSF Publications Database

... Physics Press Release 05-069Acoustic 3-D Imaging Unveils Swimming Behavior of Microscopic ... sea creatures. Now, using a newly developed, 3-D imaging system called "Fish TV," an international ...

55

International Symposium on Pattern Recognition and Acoustical Imaging, Newport Beach, CA, Feb. 4-6, 1987, Proceedings  

SciTech Connect

Various papers on pattern recognition and acoustical imaging are presented. The general subjects considered include imaging, texture and speckle analysis in medical ultrasound, parameter estimation, material characterization and NDE, and pattern recognition. Individual topics discussed include: inverse scattering theory foundations of tomography with diffracting wavefields, acoustical image reconstruction algorithms, three-dimensional motion parameter estimation by holographic acoustical systems, pattern recognition in acoustic emission experiments, image reconstruction of flaws using ramp response signatures, and pattern recognition approach to nondestructive evaluation of materials.

Ferrari, L.A.

1987-01-01

56

Fast spin echo magnetic resonance imaging: Clinical application in screening for acoustic neuroma  

Microsoft Academic Search

The advent of magnetic resonance imaging has greatly improved our ability to diagnose acoustic tumors, but it is a relatively expensive imaging modality. In the present climate of medical cost restraints, methods that reduce costs but maintain quality are extremely desirable. We report a new magnetic resonance imaging technique that uses fast spin echo without gadolinium. It provides ultrahigh-resolution images

CLOUGH SHELTON; H. RIC HARNSBERGER; ROBERT ALLEN; BRIAN KING

1996-01-01

57

Microwave-induced acoustic imaging of biological tissues Lihong V. Wang, Xuemei Zhao, Haitao Sun, and Geng Ku  

E-print Network

Microwave-induced acoustic imaging of biological tissues Lihong V. Wang, Xuemei Zhao, Haitao Sun tomographic imaging of biological tissues by use of microwave-induced acoustic signal. It was demonstrated that the acoustic signal was proportional to the intensity of the incident microwave and was related

Wang, Lihong

58

Acoustic imaging internal microstructure of a packaging material.  

E-print Network

??Microstructure of a paper-based packaging material was studied by acoustic microscopy method. The laminate structure of the packaging material contains paperboard, polymer and aluminium, which… (more)

Kao-Walter, Sharon; Levin, M.L.; Petronyuk, J.S.

2008-01-01

59

Time Reversed Acoustics and applications to earthquake location and salt dome flank imaging  

E-print Network

The objective of this thesis is to investigate the applications of Time Reversed Acoustics (TRA) to locate seismic sources and image subsurface structures. The back-propagation process of the TRA experiment can be divided ...

Lu, Rongrong

2008-01-01

60

A robust super-resolution approach with sparsity constraint in acoustic imaging $ Ning CHUa,1,  

E-print Network

A robust super-resolution approach with sparsity constraint in acoustic imaging $ Ning CHUa,1 regularization methods by simulated, real data and hybrid data respectively. It is feasible to apply our approach

Paris-Sud XI, Université de

61

A robust super-resolution approach with sparsity constraint in acoustic imaging $ Ning CHUa,1,  

E-print Network

A robust super-resolution approach with sparsity constraint in acoustic imaging $ Ning CHUa,1, deconvolution and sparse regularization methods by simulated, wind tunnel data and hybrid data respectively

Boyer, Edmond

62

A Novel Application of Time Reversed Acoustics: Salt Dome Flank Imaging Using Walkaway VSP surveys  

E-print Network

In this paper we present initial results of applying Time-Reversed Acoustics (TRA) technology to saltdome flank, seismic imaging. We created a set of synthetic traces representing a multilevel, walkaway VSP for a model ...

deHoop, Maarten V.

2006-03-01

63

Tracking Energy Flow Using a Volumetric Acoustic Intensity Imager (VAIM)  

NASA Technical Reports Server (NTRS)

A new measurement device has been invented at the Naval Research Laboratory which images instantaneously the intensity vector throughout a three-dimensional volume nearly a meter on a side. The measurement device consists of a nearly transparent spherical array of 50 inexpensive microphones optimally positioned on an imaginary spherical surface of radius 0.2m. Front-end signal processing uses coherence analysis to produce multiple, phase-coherent holograms in the frequency domain each related to references located on suspect sound sources in an aircraft cabin. The analysis uses either SVD or Cholesky decomposition methods using ensemble averages of the cross-spectral density with the fixed references. The holograms are mathematically processed using spherical NAH (nearfield acoustical holography) to convert the measured pressure field into a vector intensity field in the volume of maximum radius 0.4 m centered on the sphere origin. The utility of this probe is evaluated in a detailed analysis of a recent in-flight experiment in cooperation with Boeing and NASA on NASA s Aries 757 aircraft. In this experiment the trim panels and insulation were removed over a section of the aircraft and the bare panels and windows were instrumented with accelerometers to use as references for the VAIM. Results show excellent success at locating and identifying the sources of interior noise in-flight in the frequency range of 0 to 1400 Hz. This work was supported by NASA and the Office of Naval Research.

Klos, Jacob; Williams, Earl G.; Valdivia, Nicolas P.

2006-01-01

64

Damage monitoring in fibre reinforced mortar by combined digital image correlation and acoustic emission  

E-print Network

of hygrothermal properties. Imaging techniques for crack detection include X-ray radiography and tomography [34Damage monitoring in fibre reinforced mortar by combined digital image correlation and acoustic., Woloszyn M., Roux J.-J., 2012. Damage monitoring in fibre rein- forced mortar by combined digital image

Paris-Sud XI, Université de

65

Mosaicing of acoustic camera images K. Kim, N. Neretti and N. Intrator  

E-print Network

environments with low visibility. For optical images in those environments, often natural light, inhomogeneous illumination and low frame rate is presented. Imaging geometry of acoustic cameras. It follows that the SNR is significantly lower than in optical images. (iii) Low resolution with respect

Intrator, Nathan

66

Acoustic and optical borehole-wall imaging for fractured-rock aquifer studies  

USGS Publications Warehouse

Imaging with acoustic and optical televiewers results in continuous and oriented 360?? views of the borehole wall from which the character, relation, and orientation of lithologic and structural planar features can be defined for studies of fractured-rock aquifers. Fractures are more clearly defined under a wider range of conditions on acoustic images than on optical images including dark-colored rocks, cloudy borehole water, and coated borehole walls. However, optical images allow for the direct viewing of the character of and relation between lithology, fractures, foliation, and bedding. The most powerful approach is the combined application of acoustic and optical imaging with integrated interpretation. Imaging of the borehole wall provides information useful for the collection and interpretation of flowmeter and other geophysical logs, core samples, and hydraulic and water-quality data from packer testing and monitoring. ?? 2003 Elsevier B.V. All rights reserved.

Williams, J.H.; Johnson, C.D.

2004-01-01

67

RGB representation of two-dimensional multi-spectral acoustic data for object surface profile imaging  

NASA Astrophysics Data System (ADS)

Conventionally, acoustic imaging has been performed using a single frequency or a limited number of frequencies. However, the rich information on surface profiles, structures hidden under surfaces and material properties of objects may exhibit frequency dependence. In this study, acoustic imaging on object surface was conducted over a wide frequency range with a fine frequency step, and a method for displaying the acquired multi-spectral acoustic data was proposed. A complicated rigid surface with different profiles was illuminated by sound waves sweeping over the frequency range from 1 to 20 kHz with a 30 Hz step. The reflected sound was two-dimensionally recorded using a scanning microphone, and processed using a holographic reconstruction method. The two-dimensional distributions of obtained sound pressure at each frequency were defined as ‘multi-spectral acoustic imaging data’. Next, the multi-spectral acoustic data were transformed into a single RGB-based picture for easy understanding of the surface characteristics. The acoustic frequencies were allocated to red, green and blue using the RGB filter technique. The depths of the grooves were identified by their colours in the RGB image.

Guo, Xinhua; Wada, Yuji; Mizuno, Yosuke; Nakamura, Kentaro

2013-10-01

68

Photoacoustic section imaging using an elliptical acoustic mirror and optical detection  

NASA Astrophysics Data System (ADS)

A method is proposed that utilizes the advantages of optical ultrasound detection in two-dimensional photoacoustic section imaging, combining an optical interferometer with an acoustic mirror. The concave mirror has the shape of an elliptical cylinder and concentrates the acoustic wave generated around one focal line in the other one, where an optical beam probes the temporal evolution of acoustic pressure. This yields line projections of the acoustic sources at distances corresponding to the time of flight, which, after rotating the sample about an axis perpendicular to the optical detector, allows reconstruction of a section using the inverse Radon transform. A resolution of 120 µm within and 1.5 mm between the sections can be obtained with the setup. Compared to a bare optical probe beam, the signal-to-noise ratio (SNR) is seven times higher with the mirror. Furthermore, the imaging system is tested on a biological sample.

Nuster, Robert; Gratt, Sibylle; Passler, Klaus; Meyer, Dirk; Paltauf, Guenther

2012-03-01

69

Far-field imaging of acoustic waves by a two-dimensional sonic crystal  

Microsoft Academic Search

The negative refraction behavior and imaging effect for acoustic waves in two-dimensional sonic crystals consisting of hexagonal arrays of steel cylinders in air are studied in this paper. The negative refraction and left-handed behaviors are demonstrated by the simulation of a Gaussian beam through a slab of the sonic crystal. Imaging effects by the sonic crystal slab with effective refraction

Chunyin Qiu; Xiangdong Zhang; Zhengyou Liu

2005-01-01

70

Correlation of Imaging Sonar Acoustic Shadows and Bathymetry for ROV Terrain-Relative Localization  

E-print Network

Correlation of Imaging Sonar Acoustic Shadows and Bathymetry for ROV Terrain-Relative Localization of a remotely-operated vehicle (ROV) with respect to an a priori bathymetric terrain map. Specifically, a method visibility image is generated for a given ROV position estimate with respect to a stored terrain map

71

Creating and imaging surface acoustic waves on gallium arsenide  

NASA Astrophysics Data System (ADS)

The versatility of surface acoustic wave (SAW) devices stems from the accessibility of the propagation path to modification and detection. This has led to the integration of SAWs in a variety of novel fields, including quantum information processing. The development of technologically competitive devices requires the use of gigahertz frequency SAWs. This thesis develops fabrication processes for high frequency interdigital transducers on gallium arsenide. Optically lithography was used to create linear and stepped transducers, with a minimum feature size of 2 mum, that were driven at their fifth harmonic. The highest frequency achieved was 1435 MHz, but the power absorbed was less than 3% and insertion losses were greater than --80 dB. Further improvements in the design and fabrication are required if optically fabricated transducers are to be an alternative to transducers with narrower finger widths. Electron-beam lithography techniques were developed and used to create transducers with finger widths of 500 and 400 nm, with fundamental resonance frequencies of 1387 and 1744 MHz, respectively. The power absorbed was 3 to 6% with insertion losses greater than --45 dB. The performance characteristics can be improved by the removal of residual resist on the surface of the transducer. An indispensable tool for the characterization of one-port transducers is an all optical probe to measure the displacement field of a SAW. This work details the design and construction of a scanning Sagnac interferometer that is capable of measuring the outward displacement of a surface. The spatial resolution of the interferometer was 2:4+/-0:2 mum and the displacement sensitivity was determined to be 4+/-1 pm. The instrument was used to map the SAW displacement field from a 358MHz transducer, with results showing the resonant cavity behaviour of the fingers due to Bragg reflections. It also allowed for the direct detection of the SAW amplitude as a function of the driving frequency of the transducer. The results showed good agreement with the related S21 scattering parameter. Lastly, the interferometer was used to image the attenuated propagation of SAWs through a phononic crystal. Results showed good agreement with theoretical simulations.

Mathew, Reuble

72

Segmentation and classification of shallow subbottom acoustic data, using image processing and neural networks  

NASA Astrophysics Data System (ADS)

Subbottom acoustic profiler provides acoustic imaging of the subbottom structure constituting the upper sediment layers of the seabed, which is essential for geological and offshore geo-engineering studies. Delineation of the subbottom structure from a noisy acoustic data and classification of the sediment strata is a challenging task with the conventional signal processing techniques. Image processing techniques utilise the spatial variability of the image characteristics, known for their potential in medical imaging and pattern recognition applications. In the present study, they are found to be good in demarcating the boundaries of the sediment layers associated with weak acoustic reflectivity, masked by noisy background. The study deals with application of image processing techniques, like segmentation in identification of subbottom features and extraction of textural feature vectors using grey level co-occurrence matrix statistics. And also attempted classification using Self Organised Map, an unsupervised neural network model utilising these feature vectors. The methodology was successfully demonstrated in demarcating the different sediment layers from the subbottom images and established the sediments constituting the inferred four subsurface sediment layers differ from each other. The network model was also tested for its consistency, with repeated runs of different configuration of the network. Also the ability of simulated network was tested using a few untrained test images representing the similar environment and the classification results show a good agreement with the anticipated.

Yegireddi, Satyanarayana; Thomas, Nitheesh

2014-06-01

73

Method and apparatus for detecting internal structures of bulk objects using acoustic imaging  

DOEpatents

Apparatus for producing an acoustic image of an object according to the present invention may comprise an excitation source for vibrating the object to produce at least one acoustic wave therein. The acoustic wave results in the formation of at least one surface displacement on the surface of the object. A light source produces an optical object wavefront and an optical reference wavefront and directs the optical object wavefront toward the surface of the object to produce a modulated optical object wavefront. A modulator operatively associated with the optical reference wavefront modulates the optical reference wavefront in synchronization with the acoustic wave to produce a modulated optical reference wavefront. A sensing medium positioned to receive the modulated optical object wavefront and the modulated optical reference wavefront combines the modulated optical object and reference wavefronts to produce an image related to the surface displacement on the surface of the object. A detector detects the image related to the surface displacement produced by the sensing medium. A processing system operatively associated with the detector constructs an acoustic image of interior features of the object based on the phase and amplitude of the surface displacement on the surface of the object.

Deason, Vance A. (Idaho Falls, ID); Telschow, Kenneth L. (Idaho Falls, ID)

2002-01-01

74

An acoustic charge transport imager for high definition television applications  

NASA Technical Reports Server (NTRS)

In this report we present the progress during the second six month period of the project. This includes both experimental and theoretical work on the acoustic charge transport (ACT) portion of the chip, the theoretical program modelling of both the avalanche photodiode (APD) and the charge transfer and overflow transistor and the materials growth and fabrication part of the program.

Hunt, William D.; Brennan, Kevin F.; Summers, Chris J.

1992-01-01

75

Imaging surface acoustic waves in anisotropic and periodic media  

Microsoft Academic Search

A new technique has been developed for studying surface acoustic wave propagation. The technique, which uses non- contact immersion transducers to excite and detect ultrasound with frequencies between 1 and 20 MHz, allows convenient examination of surface waves traveling in arbitrary directions on a sample. Coupling the easy scanning of ultrasound propagation with time- resolved detection of the surface-wave amplitude

Robert Ellsworth Vines

1998-01-01

76

Acoustic tomographic imaging of temperature and flow fields in air  

NASA Astrophysics Data System (ADS)

Acoustic travel-time tomography is a remote sensing technique that uses the dependence of sound speed in air on temperature and wind speed along the sound propagation path. Travel-time measurements of acoustic signals between several sound sources and receivers travelling along different paths through a measuring area give information on the spatial distribution of temperature and flow fields within the area. After a separation of the two influences, distributions of temperature and flow can be reconstructed using inverse algorithms. As a remote sensing method, one advantage of acoustic travel-time tomography is its ability to measure temperature and flow field quantities without disturbing the area under investigation due to insertion of sensors. Furthermore, the two quantities—temperature and flow velocity—can be recorded simultaneously with this measurement method. In this paper, an acoustic tomographic measurement system is introduced which is capable of resolving three-dimensional distributions of temperature and flow fields in air within a certain volume (1.3 m × 1.0 m × 1.2 m) using 16 acoustic transmitter-receiver pairs. First, algorithms for the 3D reconstruction of distributions from line-integrated measurements are presented. Moreover, a measuring apparatus is introduced which is suited for educational purposes, for demonstration of the method as well as for indoor investigations. Example measurements within a low-speed wind tunnel with different incident flow situations (e.g. behind bluff bodies) using this system are shown. Visualizations of the flow illustrate the plausibility of the tomographically reconstructed flow structures. Furthermore, alternative individual measurement methods for temperature and flow speed provide comparable results.

Barth, Manuela; Raabe, Armin

2011-03-01

77

Exploration of amphoteric and negative refraction imaging of acoustic sources via active metamaterials  

NASA Astrophysics Data System (ADS)

The present work describes the design of three flat superlens structures for acoustic source imaging and explores an active acoustic metamaterial (AAM) to realise such a design. The first two lenses are constructed via the coordinate transform method (CTM), and their constituent materials are anisotropic. The third lens consists of a material that has both a negative density and a negative bulk modulus. In these lenses, the quality of the images is “clear” and sharp; thus, the diffraction limit of classical lenses is overcome. Finally, a multi-control strategy is developed to achieve the desired parameters and to eliminate coupling effects in the AAM.

Wen, Jihong; Shen, Huijie; Yu, Dianlong; Wen, Xisen

2013-11-01

78

Observation of damage evolution in polymer bonded explosives using acoustic emission and digital image correlation  

Microsoft Academic Search

The Acoustic Emission (AE) and Digital Image Correlation (DIC) methods have been combined to measure and evaluate the damage evolution of Polymer Bonded Explosives (PBXs) under uniaxial compression. The global damage evolution was measured by AE and the local (spatial) distribution of damage observed by DIC. It was found that a Dominant Localization Band (DLB) plays a key role in

Xian Wang; Shaopeng Ma; Yingtao Zhao; Zhongbin Zhou; Pengwan Chen

2011-01-01

79

Acoustic imaging of underground storage tank wastes: A feasibility study. Final report  

SciTech Connect

The objectives for this underground storage tank (UST) imaging investigation are: (1) to assess the feasibility of using acoustic methods in UST wastes, if shown to be feasible, develop and assess imaging strategies; (2) to assess the validity of using chemical simulants for the development of acoustic methods and equipment. This investigation examined the velocity of surrogates, both salt cake and sludge surrogates. In addition collected seismic cross well data in a real tank (114-TX) on the Hanford Reservation. Lastly, drawing on the knowledge of the simulants and the estimates of the velocities of the waste in tank 114-TX the authors generated a hypothetical model of waste in a tank and showed that non-linear travel time tomographic imaging would faithfully image that stratigraphy.

Turpening, R.; Zhu, Z.; Caravana, C.; Matarese, J. [Massachusetts Inst. of Tech., Cambridge, MA (United States). Earth Resources Lab.; Turpening, W. [Elohi Geophysical, Inc., Houston, TX (United States)

1995-12-31

80

MINACE filter: variants of realization in 4-f correlator  

NASA Astrophysics Data System (ADS)

Minimum Noise And Correlation Energy (MINACE) filters application provides good ability to recognize in case of grayscale input images of an object with background noises. For fast correlation matching MINACE filters can be used in 4-f correlators as a computer generated hologram (holographic filters). In this paper different variants of holographic filters realization were discussed. The results of correlation recognition with holographic MINACE filters are presented.

Shaulskiy, Dmitry V.; Evtikhiev, Nikolay N.; Starikov, Rostislav S.; Starikov, Sergey N.; Zlokazov, Evgeny Y.

2014-04-01

81

Time-resolved coherent X-ray diffraction imaging of surface acoustic waves  

PubMed Central

Time-resolved coherent X-ray diffraction experiments of standing surface acoustic waves, illuminated under grazing incidence by a nanofocused synchrotron beam, are reported. The data have been recorded in stroboscopic mode at controlled and varied phase between the acoustic frequency generator and the synchrotron bunch train. At each time delay (phase angle), the coherent far-field diffraction pattern in the small-angle regime is inverted by an iterative algorithm to yield the local instantaneous surface height profile along the optical axis. The results show that periodic nanoscale dynamics can be imaged at high temporal resolution in the range of 50?ps (pulse length). PMID:25294979

Nicolas, Jan-David; Reusch, Tobias; Osterhoff, Markus; Sprung, Michael; Schulein, Florian J. R.; Krenner, Hubert J.; Wixforth, Achim; Salditt, Tim

2014-01-01

82

Acoustic guiding and subwavelength imaging with sharp bending by sonic crystal  

E-print Network

A sharp bending scheme for the self-collimation of acoustic waves is proposed by simply truncating the sonic crystals. An all-angle and wide-band 90{\\deg}-bending wave guide is demonstrated with nearly perfect transmissions for Gaussian beams at a wide range of incident angles. A 90{\\deg}-bended imaging for a point source with a subwavelength resolution of 0 0.37{\\lambda} is also realized by the proposed structure. These results will find applicability in the manipulation of acoustic waves by sonic crystals.

Li, Bo; Zhao, Heping; 10.1063/1.3622652

2011-01-01

83

Acoustic guiding and subwavelength imaging with sharp bending by sonic crystal  

NASA Astrophysics Data System (ADS)

A sharp bending scheme for the self-collimation of acoustic waves is proposed by simply truncating the sonic crystals. An all-angle and wide-band 90°-bending wave guide is demonstrated with nearly perfect transmissions for Gaussian beams at a wide range of incident angles. A 90°-bended imaging for a point source with a subwavelength resolution of 0.37 ?0 is also realized by the proposed structure. These results will find applicability in the manipulation of acoustic waves by sonic crystals.

Li, Bo; Deng, Ke; Zhao, Heping

2011-08-01

84

Defect characterization by acoustic holography. Volume 1. Imaging in field environments. Final report  

SciTech Connect

Acoustic Holography (AH) equipment was used in a field environment to characterize defects in thick plate components. The program was successful and a large holographic data base was generated. Both optical and computer reconstruction techniques were used to produce AH images of selected defects. The report covers results on both production and non-production components, and describes the equipment and test configurations used to acquire the data. The portion of the program dealing with the production components includes comparative data for conventional NDE techniques (Radiographic and Ultrasonic), Acoustic Holography and destructive tests.

Holt, A.; Brophy, J.

1980-09-01

85

A synchronized particle image velocimetry and infrared thermography technique applied to an acoustic streaming flow  

PubMed Central

Subsurface coherent structures and surface temperatures are investigated using simultaneous measurements of particle image velocimetry (PIV) and infrared (IR) thermography. Results for coherent structures from acoustic streaming and associated heating transfer in a rectangular tank with an acoustic horn mounted horizontally at the sidewall are presented. An observed vortex pair develops and propagates in the direction along the centerline of the horn. From the PIV velocity field data, distinct kinematic regions are found with the Lagrangian coherent structure (LCS) method. The implications of this analysis with respect to heat transfer and related sonochemical applications are discussed. PMID:24347810

Sou, In Mei; Layman, Christopher N.; Ray, Chittaranjan

2013-01-01

86

Investigation of an acoustical holography system for real-time imaging  

NASA Astrophysics Data System (ADS)

A new prototype imaging system based on ultrasound transmission through the object of interest -- acoustical holography -- was developed which incorporates significant improvements in acoustical and optical design. This system is being evaluated for potential clinical application in the musculoskeletal system, interventional radiology, pediatrics, monitoring of tumor ablation, vascular imaging and breast imaging. System limiting resolution was estimated using a line-pair target with decreasing line thickness and equal separation. For a swept frequency beam from 2.6 - 3.0 MHz, the minimum resolution was 0.5 lp/mm. Apatite crystals were suspended in castor oil to approximate breast microcalcifications. Crystals from 0.425 - 1.18 mm in diameter were well resolved in the acoustic zoom mode. Needle visibility was examined with both a 14-gauge biopsy needle and a 0.6 mm needle. The needle tip was clearly visible throughout the dynamic imaging sequence as it was slowly inserted into a RMI tissue-equivalent breast biopsy phantom. A selection of human images was acquired in several volunteers: a 25 year-old female volunteer with normal breast tissue, a lateral view of the elbow joint showing muscle fascia and tendon insertions, and the superficial vessels in the forearm. Real-time video images of these studies will be presented. In all of these studies, conventional sonography was used for comparison. These preliminary investigations with the new prototype acoustical holography system showed favorable results in comparison to state-of-the-art pulse-echo ultrasound and demonstrate it to be suitable for further clinical study. The new patient interfaces will facilitate orthopedic soft tissue evaluation, study of superficial vascular structures and potentially breast imaging.

Fecht, Barbara A.; Andre, Michael P.; Garlick, George F.; Shelby, Ronald L.; Shelby, Jerod O.; Lehman, Constance D.

1998-07-01

87

Acoustic streaming in lithotripsy fields: preliminary observation using a particle image velocimetry method.  

PubMed

This study considers the acoustic streaming in water produced by a lithotripsy pulse. Particle image velocimetry (PIV) method was employed to visualize the acoustic streaming produced by an electromagnetic shock wave generator using video images of the light scattering particles suspended in water. Visualized streaming features including several local peaks and vortexes around or at the beam focus were easily seen with naked eyes over all settings of the lithotripter from 10 to 18 kV. Magnitudes of the peak streaming velocity measured vary in the range of 10-40 mm s(-1) with charging voltage settings. Since the streaming velocity was estimated on the basis of a series of the video images of particles averaged over 1/60s, the time resolution limited by the video frame rate which is 1-2 orders of magnitude larger than driving acoustic activities, measured velocities are expected to be underestimated and were shown a similar order of magnitude lower than those calculated from a simple theoretical consideration. Despite such an underestimation, it was shown that, as predicted by theory, the magnitude of the streaming velocity measured by the present PIV method was proportional to acoustic intensity. In particular it has almost a linear correlation with peak negative pressures (r=0.98683, p=0.0018). PMID:16376400

Choi, Min Joo; Doh, Doeg Hee; Hwang, Tae Gyu; Cho, Chu Hyun; Paeng, Dong Guk; Rim, Gun Hee; Coleman, A J

2006-02-01

88

Integrating Acoustic Imaging of Flow Regimes With Bathymetry: A Case Study, Main Endeavor Field  

NASA Astrophysics Data System (ADS)

A unified view of the seafloor and the hydrothermal flow regimes (plumes and diffuse flow) is constructed for three major vent clusters in the Main Endeavour Field (e.g., Grotto, S&M, and Salut) of the Endeavour Segment, Juan de Fuca Ridge. The Main Endeavour Field is one of RIDGE 2000's Integrated Study Sites. A variety of visualization techniques are used to reconstruct the plumes (3D) and the diffuse flow field (2D) based on our acoustic imaging data set (July 2000 cruise). Plumes are identified as volumes of high backscatter intensity (indicating high particulate content or sharp density contrasts due to temperature variations) that remained high intensity when successive acoustic pings were subtracted (indicating that the acoustic targets producing the backscatter were in motion). Areas of diffuse flow are detected using our acoustic scintillation technique (AST). For the Grotto vent region (where a new Doppler technique was used to estimate vertical velocities in the plume), we estimate the areal partitioning between black smoker and diffuse flow in terms of volume fluxes. The volumetric and areal regions, where plume and diffuse flow were imaged, are registered over the bathymetry and compared to geologic maps of each region. The resulting images provide a unified view of the seafloor by integrating hydrothermal flow with geology.

Bemis, K. G.; Rona, P. A.; Jackson, D. R.; Jones, C. D.

2003-12-01

89

An acoustic charge transport imager for high definition television applications  

NASA Astrophysics Data System (ADS)

This report covers: (1) invention of a new, ultra-low noise, low operating voltage APD which is expected to offer far better performance than the existing volume doped APD device; (2) performance of a comprehensive series of experiments on the acoustic and piezoelectric properties of ZnO films sputtered on GaAs which can possibly lead to a decrease in the required rf drive power for ACT devices by 15dB; (3) development of an advanced, hydrodynamic, macroscopic simulator used for evaluating the performance of ACT and CTD devices and aiding in the development of the next generation of devices; (4) experimental development of CTD devices which utilize a p-doped top barrier demonstrating charge storage capacity and low leakage currents; (5) refinements in materials growth techniques and in situ controls to lower surface defect densities to record levels as well as increase material uniformity and quality.

Hunt, William D.; Brennan, Kevin F.; Summers, Christopher J.

1993-09-01

90

An acoustic charge transport imager for high definition television applications  

NASA Technical Reports Server (NTRS)

This report covers: (1) invention of a new, ultra-low noise, low operating voltage APD which is expected to offer far better performance than the existing volume doped APD device; (2) performance of a comprehensive series of experiments on the acoustic and piezoelectric properties of ZnO films sputtered on GaAs which can possibly lead to a decrease in the required rf drive power for ACT devices by 15dB; (3) development of an advanced, hydrodynamic, macroscopic simulator used for evaluating the performance of ACT and CTD devices and aiding in the development of the next generation of devices; (4) experimental development of CTD devices which utilize a p-doped top barrier demonstrating charge storage capacity and low leakage currents; (5) refinements in materials growth techniques and in situ controls to lower surface defect densities to record levels as well as increase material uniformity and quality.

Hunt, William D.; Brennan, Kevin F.; Summers, Christopher J.

1993-01-01

91

Modern Techniques in Acoustical Signal and Image Processing  

SciTech Connect

Acoustical signal processing problems can lead to some complex and intricate techniques to extract the desired information from noisy, sometimes inadequate, measurements. The challenge is to formulate a meaningful strategy that is aimed at performing the processing required even in the face of uncertainties. This strategy can be as simple as a transformation of the measured data to another domain for analysis or as complex as embedding a full-scale propagation model into the processor. The aims of both approaches are the same--to extract the desired information and reject the extraneous, that is, develop a signal processing scheme to achieve this goal. In this paper, we briefly discuss this underlying philosophy from a ''bottom-up'' approach enabling the problem to dictate the solution rather than visa-versa.

Candy, J V

2002-04-04

92

Phase Time and Envelope Time in Time-Distance Analysis and Acoustic Imaging  

NASA Technical Reports Server (NTRS)

Time-distance analysis and acoustic imaging are two related techniques to probe the local properties of solar interior. In this study, we discuss the relation of phase time and envelope time between the two techniques. The location of the envelope peak of the cross correlation function in time-distance analysis is identified as the travel time of the wave packet formed by modes with the same w/l. The phase time of the cross correlation function provides information of the phase change accumulated along the wave path, including the phase change at the boundaries of the mode cavity. The acoustic signals constructed with the technique of acoustic imaging contain both phase and intensity information. The phase of constructed signals can be studied by computing the cross correlation function between time series constructed with ingoing and outgoing waves. In this study, we use the data taken with the Taiwan Oscillation Network (TON) instrument and the Michelson Doppler Imager (MDI) instrument. The analysis is carried out for the quiet Sun. We use the relation of envelope time versus distance measured in time-distance analyses to construct the acoustic signals in acoustic imaging analyses. The phase time of the cross correlation function of constructed ingoing and outgoing time series is twice the difference between the phase time and envelope time in time-distance analyses as predicted. The envelope peak of the cross correlation function between constructed ingoing and outgoing time series is located at zero time as predicted for results of one-bounce at 3 mHz for all four data sets and two-bounce at 3 mHz for two TON data sets. But it is different from zero for other cases. The cause of the deviation of the envelope peak from zero is not known.

Chou, Dean-Yi; Duvall, Thomas L.; Sun, Ming-Tsung; Chang, Hsiang-Kuang; Jimenez, Antonio; Rabello-Soares, Maria Cristina; Ai, Guoxiang; Wang, Gwo-Ping; Goode Philip; Marquette, William; Ehgamberdiev, Shuhrat; Landenkov, Oleg

1999-01-01

93

Synchronized imaging and acoustic analysis of the upper airway in patients with sleep-disordered breathing.  

PubMed

Progressive narrowing of the upper airway increases airflow resistance and can produce snoring sounds and apnea/hypopnea events associated with sleep-disordered breathing due to airway collapse. Recent studies have shown that acoustic properties during snoring can be altered with anatomic changes at the site of obstruction. To evaluate the instantaneous association between acoustic features of snoring and the anatomic sites of obstruction, a novel method was developed and applied in nine patients to extract the snoring sounds during sleep while performing dynamic magnetic resonance imaging (MRI). The degree of airway narrowing during the snoring events was then quantified by the collapse index (ratio of airway diameter preceding and during the events) and correlated with the synchronized acoustic features. A total of 201 snoring events (102 pure retropalatal and 99 combined retropalatal and retroglossal events) were recorded, and the collapse index as well as the soft tissue vibration time were significantly different between pure retropalatal (collapse index, 24? ± ?11%; vibration time, 0.2? ± ?0.3?s) and combined (retropalatal and retroglossal) snores (collapse index, 13? ± ?7% [P ? 0.0001]; vibration time, 1.2? ± ?0.7?s [P ? 0.0001]). The synchronized dynamic MRI and acoustic recordings successfully characterized the sites of obstruction and established the dynamic relationship between the anatomic site of obstruction and snoring acoustics. PMID:25402604

Chang, Yi-Chung; Huon, Leh-Kiong; Pham, Van-Truong; Chen, Yunn-Jy; Jiang, Sun-Fen; Shih, Tiffany Ting-Fang; Tran, Thi-Thao; Wang, Yung-Hung; Lin, Chen; Tsao, Jenho; Lo, Men-Tzung; Wang, Pa-Chun

2014-12-01

94

Focused acoustic beam imaging of grain structure and local Young's modulus with Rayleigh and surface skimming longitudinal waves  

NASA Astrophysics Data System (ADS)

The interaction of a focused acoustic beam with materials generates Rayleigh surface waves (RSW) and surface skimming longitudinal waves (SSLW). Acoustic microscopic investigations have used the RSW amplitude and the velocity measurements, extensively for grain structure analysis. Although, the presence of SSLW has been recognized, it is rarely used in acoustic imaging. This paper presents an approach to perform microstructure imaging and local elastic modulus measurements by combining both RSW and SSLW. The acoustic imaging of grain structure was performed by measuring the amplitude of RSW and SSLW signal. The microstructure images obtained on the same region of the samples with RSW and SSLW are compared and the difference in the contrast observed is discussed based on the propagation characteristics of the individual surface waves. The velocity measurements are determined by two point defocus method. The surface wave velocities of RSW and SSLW of the same regions of the sample are combined and presented as average Young's modulus image.

Martin, R. W.; Sathish, S.; Blodgett, M. P.

2013-01-01

95

Focused acoustic beam imaging of grain structure and local Young's modulus with Rayleigh and surface skimming longitudinal waves  

SciTech Connect

The interaction of a focused acoustic beam with materials generates Rayleigh surface waves (RSW) and surface skimming longitudinal waves (SSLW). Acoustic microscopic investigations have used the RSW amplitude and the velocity measurements, extensively for grain structure analysis. Although, the presence of SSLW has been recognized, it is rarely used in acoustic imaging. This paper presents an approach to perform microstructure imaging and local elastic modulus measurements by combining both RSW and SSLW. The acoustic imaging of grain structure was performed by measuring the amplitude of RSW and SSLW signal. The microstructure images obtained on the same region of the samples with RSW and SSLW are compared and the difference in the contrast observed is discussed based on the propagation characteristics of the individual surface waves. The velocity measurements are determined by two point defocus method. The surface wave velocities of RSW and SSLW of the same regions of the sample are combined and presented as average Young's modulus image.

Martin, R. W.; Sathish, S. [University of Dayton Research Institute, Structural Integrity Division 300 College Park Drive, Dayton, OH, 45469 (United States); Blodgett, M. P. [Air Force Research Lab, RXCA, Wright Patterson AFB, OH, 45433 (United States)

2013-01-25

96

Synthetic aperture acoustic imaging of canonical targets with a 2-15 kHz linear FM chirp  

NASA Astrophysics Data System (ADS)

Synthetic aperture image reconstruction applied to outdoor acoustic recordings is presented. Acoustic imaging is an alternate method having several military relevant advantages such as being immune to RF jamming, superior spatial resolution, capable of standoff side and forward-looking scanning, and relatively low cost, weight and size when compared to 0.5 - 3 GHz ground penetrating radar technologies. Synthetic aperture acoustic imaging is similar to synthetic aperture radar, but more akin to synthetic aperture sonar technologies owing to the nature of longitudinal or compressive wave propagation in the surrounding acoustic medium. The system's transceiver is a quasi mono-static microphone and audio speaker pair mounted on a rail 5meters in length. Received data sampling rate is 80 kHz with a 2- 15 kHz Linear Frequency Modulated (LFM) chirp, with a pulse repetition frequency (PRF) of 10 Hz and an inter-pulse period (IPP) of 50 milliseconds. Targets are positioned within the acoustic scene at slant range of two to ten meters on grass, dirt or gravel surfaces, and with and without intervening metallic chain link fencing. Acoustic image reconstruction results in means for literal interpretation and quantifiable analyses. A rudimentary technique characterizes acoustic scatter at the ground surfaces. Targets within the acoustic scene are first digitally spotlighted and further processed, providing frequency and aspect angle dependent signature information.

Vignola, Joseph F.; Judge, John A.; Good, Chelsea E.; Bishop, Steven S.; Gugino, Peter M.; Soumekh, Mehrdad

2011-06-01

97

Methods And Systems For Using Reference Images In Acoustic Image Processing  

DOEpatents

A method and system of examining tissue are provided in which a field, including at least a portion of the tissue and one or more registration fiducials, is insonified. Scattered acoustic information, including both transmitted and reflected waves, is received from the field. A representation of the field, including both the tissue and the registration fiducials, is then derived from the received acoustic radiation.

Moore, Thomas L. (Livermore, CA); Barter, Robert Henry (Oakland, CA)

2005-01-04

98

Quantitative high-resolution acoustic imaging of the seafloor  

NASA Astrophysics Data System (ADS)

Quantifying the properties of the seafloor interface and near surface (a few tens of meters) is of considerable interest to science as well as industry. Scales of interest range from the order of tens of kilometers (survey size) down to less than a centimeter. These scales can be probed using an AUV equipped with a broadband source and a short streamer. The data are processed for energy (rather than peak) reflection coefficients and scattering cross-section versus bi-static angle. In order to tackle spatial scales ranging over 8 orders of magnitude of, it is useful to divide the parameter space into deterministic and stochastic parameters. The energy reflection coefficients contain information on deterministic properties including sound speed, density and attenuation vs depth in the upper tens of meters of sediment. Vertical resolution is a function of depth, but typically of order 0.1 m near surface. The statistical properties of the smaller scales, i.e., seafloor roughness and/or volume heterogeneities are obtained from the bi-static scattering data. Physics-based models are used to relate the sediment micro-structure (the Buckingham model) and sediment fluctuations (the Von Karman spectrum) to the acoustic observables. Quantitative parameter and inter-parameter uncertainties are obtained from Bayesian methods for both deterministic and stochastic parameters.

Holland, C. W.; Dettmer, J.; Steininger, G.; Dosso, S. E.

2013-12-01

99

Automated Detection Framework of the Calcified Plaque with Acoustic Shadowing in IVUS Images  

PubMed Central

Intravascular Ultrasound (IVUS) is one ultrasonic imaging technology to acquire vascular cross-sectional images for the visualization of the inner vessel structure. This technique has been widely used for the diagnosis and treatment of coronary artery diseases. The detection of the calcified plaque with acoustic shadowing in IVUS images plays a vital role in the quantitative analysis of atheromatous plaques. The conventional method of the calcium detection is manual drawing by the doctors. However, it is very time-consuming, and with high inter-observer and intra-observer variability between different doctors. Therefore, the computer-aided detection of the calcified plaque is highly desired. In this paper, an automated method is proposed to detect the calcified plaque with acoustic shadowing in IVUS images by the Rayleigh mixture model, the Markov random field, the graph searching method and the prior knowledge about the calcified plaque. The performance of our method was evaluated over 996 in-vivo IVUS images acquired from eight patients, and the detected calcified plaques are compared with manually detected calcified plaques by one cardiology doctor. The experimental results are quantitatively analyzed separately by three evaluation methods, the test of the sensitivity and specificity, the linear regression and the Bland-Altman analysis. The first method is used to evaluate the ability to distinguish between IVUS images with and without the calcified plaque, and the latter two methods can respectively measure the correlation and the agreement between our results and manual drawing results for locating the calcified plaque in the IVUS image. High sensitivity (94.68%) and specificity (95.82%), good correlation and agreement (>96.82% results fall within the 95% confidence interval in the Student t-test) demonstrate the effectiveness of the proposed method in the detection of the calcified plaque with acoustic shadowing in IVUS images. PMID:25372784

Liu, Xin; Huang, Wenhua; Zhang, Heye; Tan, Ning; Hau, William Kongto; Zhang, Yuan-Ting; Liu, Huafeng

2014-01-01

100

Automated Detection Framework of the Calcified Plaque with Acoustic Shadowing in IVUS Images.  

PubMed

Intravascular Ultrasound (IVUS) is one ultrasonic imaging technology to acquire vascular cross-sectional images for the visualization of the inner vessel structure. This technique has been widely used for the diagnosis and treatment of coronary artery diseases. The detection of the calcified plaque with acoustic shadowing in IVUS images plays a vital role in the quantitative analysis of atheromatous plaques. The conventional method of the calcium detection is manual drawing by the doctors. However, it is very time-consuming, and with high inter-observer and intra-observer variability between different doctors. Therefore, the computer-aided detection of the calcified plaque is highly desired. In this paper, an automated method is proposed to detect the calcified plaque with acoustic shadowing in IVUS images by the Rayleigh mixture model, the Markov random field, the graph searching method and the prior knowledge about the calcified plaque. The performance of our method was evaluated over 996 in-vivo IVUS images acquired from eight patients, and the detected calcified plaques are compared with manually detected calcified plaques by one cardiology doctor. The experimental results are quantitatively analyzed separately by three evaluation methods, the test of the sensitivity and specificity, the linear regression and the Bland-Altman analysis. The first method is used to evaluate the ability to distinguish between IVUS images with and without the calcified plaque, and the latter two methods can respectively measure the correlation and the agreement between our results and manual drawing results for locating the calcified plaque in the IVUS image. High sensitivity (94.68%) and specificity (95.82%), good correlation and agreement (>96.82% results fall within the 95% confidence interval in the Student t-test) demonstrate the effectiveness of the proposed method in the detection of the calcified plaque with acoustic shadowing in IVUS images. PMID:25372784

Gao, Zhifan; Guo, Wei; Liu, Xin; Huang, Wenhua; Zhang, Heye; Tan, Ning; Hau, William Kongto; Zhang, Yuan-Ting; Liu, Huafeng

2014-01-01

101

Adapting MRI acoustic radiation force imaging for in vivo human brain focused ultrasound applications.  

PubMed

A variety of magnetic resonance imaging acoustic radiation force imaging (MR-ARFI) pulse sequences as the means for image guidance of focused ultrasound therapy have been recently developed and tested ex vivo and in animal models. To successfully translate MR-ARFI guidance into human applications, ensuring that MR-ARFI provides satisfactory image quality in the presence of patient motion and deposits safe amount of ultrasound energy during image acquisition is necessary. The first aim of this work was to study the effect of motion on in vivo displacement images of the brain obtained with 2D Fourier transform spin echo MR-ARFI. Repeated bipolar displacement encoding configuration was shown less sensitive to organ motion. The optimal signal-to-noise ratio of displacement images was found for the duration of encoding gradients of 12 ms. The second aim was to further optimize the displacement signal-to-noise ratio for a particular tissue type by setting the time offset between the ultrasound emission and encoding based on the tissue response to acoustic radiation force. A method for measuring tissue response noninvasively was demonstrated. Finally, a new method for simultaneous monitoring of tissue heating during MR-ARFI acquisition was presented to enable timely adjustment of the ultrasound energy aimed at ensuring the safety of the MR-ARFI acquisition. PMID:22555751

Kaye, Elena A; Pauly, Kim Butts

2013-03-01

102

Acoustic pressure wave generation within an MR imaging system: potential medical applications.  

PubMed

The static magnetic field of a magnetic resonance (MR) imaging system was used as a component of an electromagnetic transducer for generating acoustic pressure waves. To permit limited focusing, the transducer was constructed from a conductive thin plate shaped like a section of a sphere. The plate was placed within the static field of the MR unit (B0 = 1.5 T), and current pulses with a rise time of 73 nsec and amplitude of 1.0 kA were applied to it. Hydrophonic recording demonstrated a shock wave with a peak pressure of 4.8 MPa at the approximated focal point. MR guidance of lithotripsy would be particularly useful to limit undesirable soft-tissue damage. It is also suggested that the integration of an acoustic pressure wave generator with MR imaging and control provides a novel technology for the treatment of solid soft-tissue tumors. PMID:1790388

Jolesz, F A; Jakab, P D

1991-01-01

103

Near-Field Imaging with Sound: An Acoustic STM Model  

ERIC Educational Resources Information Center

The invention of scanning tunneling microscopy (STM) 30 years ago opened up a visual window to the nano-world and sparked off a bunch of new methods for investigating and controlling matter and its transformations at the atomic and molecular level. However, an adequate theoretical understanding of the method is demanding; STM images can be…

Euler, Manfred

2012-01-01

104

A magnetic resonance imaging study on the articulatory and acoustic speech parameters of Malay vowels  

PubMed Central

The phonetic properties of six Malay vowels are investigated using magnetic resonance imaging (MRI) to visualize the vocal tract in order to obtain dynamic articulatory parameters during speech production. To resolve image blurring due to the tongue movement during the scanning process, a method based on active contour extraction is used to track tongue contours. The proposed method efficiently tracks tongue contours despite the partial blurring of MRI images. Consequently, the articulatory parameters that are effectively measured as tongue movement is observed, and the specific shape of the tongue and its position for all six uttered Malay vowels are determined. Speech rehabilitation procedure demands some kind of visual perceivable prototype of speech articulation. To investigate the validity of the measured articulatory parameters based on acoustic theory of speech production, an acoustic analysis based on the uttered vowels by subjects has been performed. As the acoustic speech and articulatory parameters of uttered speech were examined, a correlation between formant frequencies and articulatory parameters was observed. The experiments reported a positive correlation between the constriction location of the tongue body and the first formant frequency, as well as a negative correlation between the constriction location of the tongue tip and the second formant frequency. The results demonstrate that the proposed method is an effective tool for the dynamic study of speech production. PMID:25060583

2014-01-01

105

Two dimensional nonlinear frequency-mixing photo-acoustic imaging of a crack and observation of crack phantoms  

NASA Astrophysics Data System (ADS)

A two-dimensional imaging of a crack by nonlinear frequency-mixing photo-acoustic method is reported. The imaging contrast is due to nonlinear photo-thermo-acoustic processes taking place in case of simultaneous excitation by lasers of thermo-elastic and acoustic waves in the vicinity of the cracks. The images are obtained by scanning of two co-focused laser beams in region of crack location. The first cw laser beam, modulated in intensity at low frequency fL, generates a thermo-elastic wave, which is able to strongly periodically modulate the local crack rigidity up to complete closing/opening of the crack. The second cw laser beam, intensity modulated at much higher frequency fH, generates an acoustic wave incident on the breathing crack. The crack rigidity is also influenced by the stationary non-modulated inhomogeneous thermal stresses caused by the stationary heating of the sample by both lasers. The main contribution to imaging contrast comes from the strong dependence of the reflectivity of acoustic waves on the crack rigidity. The modulation of crack rigidity by thermo-elastic wave leads to the parametric modulation of the reflected acoustic waves and the generation in the spectrum of the acoustic field of the side lobes, which are separated from fH by the integer number of fL. Scan images of a crack with an amplitude dynamics up to 40 dB and a spatial resolution better than 100 ?m, are obtained through the mapping of nonlinear side lobe amplitudes. The observed dependences of the images on the power of the lasers are discussed and the physical explanation of the appearance of crack phantom images at high level of optical excitation is proposed. For comparison and elucidation of spatial resolution issues related to this imaging method, the one-dimensional images, obtained with one laser beam focus position fixed and the second beam focus position scanning, are also presented and discussed.

Mezil, Sylvain; Chigarev, Nikolay; Tournat, Vincent; Gusev, Vitalyi

2013-11-01

106

Effects of acoustic heterogeneities on transcranial brain imaging with microwave-induced thermoacoustic tomography  

PubMed Central

The effects of acoustic heterogeneities on transcranial brain imaging with microwave-induced thermoacoustic tomography were studied. A numerical model for calculating the propagation of thermoacoustic waves through the skull was developed and experimentally examined. The model takes into account wave reflection and refraction at the skull surfaces and therefore provides improved accuracy for the reconstruction. To evaluate when the skull-induced effects could be ignored in reconstruction, the reconstructed images obtained by the proposed method were further compared with those obtained with the method based on homogeneous acoustic properties. From simulation and experimental results, it was found that when the target region is close to the center of the brain, the effects caused by the skull layer are minimal and both reconstruction methods work well. As the target region becomes closer to the interface between the skull and brain tissue, however, the skull-induced distortion becomes increasingly severe, and the reconstructed image would be strongly distorted without correcting those effects. In this case, the proposed numerical method can improve image quality by taking into consideration the wave refraction and mode conversion at the skull surfaces. This work is important for obtaining good brain images when the thickness of the skull cannot be ignored. PMID:18697545

Jin, Xing; Li, Changhui; Wang, Lihong V.

2008-01-01

107

Acoustic Radiation Force Impulse Imaging of Mechanical Stiffness Propagation in Myocardial Tissue  

PubMed Central

Acoustic radiation force impulse (ARFI) imaging has been shown to be capable of imaging local myocardial stiffness changes throughout the cardiac cycle. Expanding on these results, the authors present experiments using cardiac ARFI imaging to visualize and quantify the propagation of mechanical stiffness during ventricular systole. In vivo ARFI images of the left ventricular free wall of two exposed canine hearts were acquired. Images were formed while the heart was externally paced by one of two electrodes positioned on the epicardial surface and either side of the imaging plane. Two-line M-mode ARFI images were acquired at a sampling frequency of 120 Hz while the heart was paced from an external stimulating electrode. Two-dimensional ARFI images were also acquired, and an average propagation velocity across the lateral field of view was calculated. Directions and speeds of myocardial stiffness propagation were measured and compared with the propagations derived from the local electrocardiogram (ECG), strain, and tissue velocity measurements estimated during systole. In all ARFI images, the direction of myocardial stiffness propagation was seen to be away from the stimulating electrode and occurred with similar velocity magnitudes in either direction. When compared with the local epicardial ECG, the mechanical stiffness waves were observed to travel in the same direction as the propagating electrical wave and with similar propagation velocities. In a comparison between ARFI, strain, and tissue velocity imaging, the three methods also yielded similar propagation velocities. PMID:22972912

Hsu, Stephen J.; Byram, Brett C.; Bouchard, Richard R.; Dumont, Douglas M.; Wolf, Patrick D.; Trahey, Gregg E.

2012-01-01

108

Lower-Limb Vascular Imaging with Acoustic Radiation Force Elastography: Demonstration of In Vivo Feasibility  

PubMed Central

Acoustic radiation force impulse (ARFI) imaging characterizes the mechanical properties of tissue by measuring displacement resulting from applied ultrasonic radiation force. In this paper, we describe the current status of ARFI imaging for lower-limb vascular applications and present results from both tissue-mimicking phantoms and in vivo experiments. Initial experiments were performed on vascular phantoms constructed with polyvinyl alcohol for basic evaluation of the modality. Multilayer vessels and vessels with compliant occlusions of varying plaque load were evaluated with ARFI imaging techniques. Phantom layers and plaque are well resolved in the ARFI images, with higher contrast than B-mode, demonstrating the ability of ARFI imaging to identify regions of different mechanical properties. Healthy human subjects and those with diagnosed lower-limb peripheral arterial disease were imaged. Proximal and distal vascular walls are well visualized in ARFI images, with higher mean contrast than corresponding B-mode images. ARFI images reveal information not observed by conventional ultrasound and lend confidence to the feasibility of using ARFI imaging during lower-limb vascular workup. PMID:19473912

Dumont, Douglas; Dahl, Jeremy; Miller, Elizabeth; Allen, Jason; Fahey, Brian; Trahey, Gregg

2010-01-01

109

Microstructure Imaging Using Frequency Spectrum Spatially Resolved Acoustic Spectroscopy F-Sras  

NASA Astrophysics Data System (ADS)

Material microstructure can have a profound effect on the mechanical properties of a component, such as strength and resistance to creep and fatigue. SRAS—spatially resolved acoustic spectroscopy—is a laser ultrasonic technique which can image microstructure using highly localized surface acoustic wave (SAW) velocity as a contrast mechanism, as this is sensitive to crystallographic orientation. The technique is noncontact, nondestructive, rapid, can be used on large components, and is highly tolerant of acoustic aberrations. Previously, the SRAS technique has been demonstrated using a fixed frequency excitation laser and a variable grating period (?-vector) to determine the most efficiently generated SAWs, and hence the velocity. Here, we demonstrate an implementation which uses a fixed grating period with a broadband laser excitation source. The velocity is determined by analyzing the measured frequency spectrum. Experimental results using this "frequency spectrum SRAS" (f-SRAS) method are presented. Images of microstructure on an industrially relevant material are compared to those obtained using the previous SRAS method ("k-SRAS"), excellent agreement is observed. Moreover, f-SRAS is much simpler and potentially much more rapid than k-SRAS as the velocity can be determined at each sample point in one single laser shot, rather than scanning the grating period.

Sharples, S. D.; Li, W.; Clark, M.; Somekh, M. G.

2010-02-01

110

Full-Wave Iterative Image Reconstruction in Photoacoustic Tomography with Acoustically Inhomogeneous Media  

E-print Network

Existing approaches to image reconstruction in photoacoustic computed tomography (PACT) with acoustically heterogeneous media are limited to weakly varying media, are computationally burdensome, and/or cannot effectively mitigate the effects of measurement data incompleteness and noise. In this work, we develop and investigate a discrete imaging model for PACT that is based on the exact photoacoustic (PA) wave equation and facilitates the circumvention of these limitations. A key contribution of the work is the establishment of a procedure to implement a matched forward and backprojection operator pair associated with the discrete imaging model, which permits application of a wide-range of modern image reconstruction algorithms that can mitigate the effects of data incompleteness and noise. The forward and backprojection operators are based on the k-space pseudospectral method for computing numerical solutions to the PA wave equation in the time domain. The developed reconstruction methodology is investigated...

Huang, Chao; Nie, Liming; Wang, Lihong V; Anastasio, Mark A

2013-01-01

111

Acoustical holographic Siamese image technique for imaging radial cracks in reactor piping  

SciTech Connect

This paper describes a unique technique (i.e., ''Siamese imaging'') for imaging quasi-vertical defects in reactor pipe weldments. The Siamese image is a bi-symmetrical view of the inner surface defect. Image construction geometry consists of two probes (i.e., source/receiver) operating either from opposite sides or the same side of the defect to be imaged. As the probes are scanned across a lower surface connected defect, they encounter two images - first the normal upright image and then the inverted image. The final integrated image consists of two images connected along their baselines, thus we call it a ''Siamese image.'' The experimental imaging results on simulated and natural cracks in reactor piping weldments graphically illustrate this unique technique. Excellent images of mechanical fatique and thermal cracks were obtained on ferritic and austenitic piping.

Collins, H.D.; Gribble, R.P.

1985-04-01

112

Assessing and improving acoustic radiation force image quality using a 1.5D transducer design  

PubMed Central

A 1.5D transducer array was developed to improve acoustic radiation force impulse (ARFI) imaging signal-to-noise ratio (SNRARFI) and image contrast relative to a conventional 1D array. To predict performance gains from the proposed 1.5D transducer array, an analytical model for SNRARFI upper bound was derived. The analytical model and 1.5D ARFI array were validated using a finite element model-based numerical simulation framework. The analytical model demonstrated good agreement with numerical results (correlation coefficient = 0.995), and simulated lesion images yielded a significant (2.92 dB; p < 0.001) improvement in contrast-to-noise ratio when rendered using the 1.5D ARFI array. PMID:22828855

Dhanaliwala, Ali .H.; Hossack, John A.; Mauldin, F. William

2014-01-01

113

Imaging of Acoustically Coupled Oscillations Due to Flow Past a Shallow Cavity: Effect of Cavity Length Scale  

SciTech Connect

Flow-acoustic interactions due to fully turbulent inflow past a shallow axisymmetric cavity mounted in a pipe are investigated using a technique of high-image-density particle image velocimetry in conjunction with unsteady pressure measurements. This imaging leads to patterns of velocity, vorticity, streamline topology, and hydrodynamic contributions to the acoustic power integral. Global instantaneous images, as well as time-averaged images, are evaluated to provide insight into the flow physics during tone generation. Emphasis is on the manner in which the streamwise length scale of the cavity alters the major features of the flow structure. These image-based approaches allow identification of regions of the unsteady shear layer that contribute to the instantaneous hydrodynamic component of the acoustic power, which is necessary to maintain a flow tone. In addition, combined image analysis and pressure measurements allow categorization of the instantaneous flow patterns that are associated with types of time traces and spectra of the fluctuating pressure. In contrast to consideration based solely on pressure spectra, it is demonstrated that locked-on tones may actually exhibit intermittent, non-phase-locked images, apparently due to low damping of the acoustic resonator. Locked-on flow tones (without modulation or intermittency), locked-on flow tones with modulation, and non-locked-on oscillations with short-term, highly coherent fluctuations are defined and represented by selected cases. Depending on which of,these regimes occur, the time-averaged Q (quality)-factor and the dimensionless peak pressure are substantially altered.

P. Oshkai; M. Geveci; D. Rockwell; M. Pollack

2002-12-12

114

Quantification and improvement of speech transmission performance using headphones in acoustic stimulated functional magnetic resonance imaging.  

PubMed

Functional magnetic resonance imaging (fMRI) has made a major contribution to the understanding of higher brain function, but fMRI with auditory stimulation, used in the planning of brain tumor surgery, is often inaccurate because there is a risk that the sounds used in the trial may not be correctly transmitted to the subjects due to acoustic noise. This prompted us to devise a method of digitizing sound transmission ability from the accuracy rate of 67 syllables, classified into three types. We evaluated this with and without acoustic noise during imaging. We also improved the structure of the headphones and compared their sound transmission ability with that of conventional headphones attached to an MRI device (a GE Signa HDxt 3.0 T). We calculated and compared the sound transmission ability of the conventional headphones with that of the improved model. The 95 percent upper confidence limit (UCL) was used as the threshold for accuracy rate of hearing for both headphone models. There was a statistically significant difference between the conventional model and the improved model during imaging (p < 0.01). The rate of accuracy of the improved model was 16 percent higher. 29 and 22 syllables were accurate at a 95% UCL in the improved model and the conventional model, respectively. This study revealed the evaluation system used in this study to be useful for correctly identifying syllables during fMRI. PMID:25327421

Yamamura, Ken Ichiro; Takatsu, Yasuo; Miyati, Tosiaki; Kimura, Tetsuya

2014-10-01

115

Contrast in Intracardiac Acoustic Radiation Force Impulse Images of Radiofrequency Ablation Lesions  

PubMed Central

We have previously shown that intracardiac acoustic radiation force impulse (ARFI) imaging visualizes tissue stiffness changes caused by radiofrequency ablation (RFA). The objectives of this in vivo study were to (1) quantify measured ARFI-induced displacements in RFA lesion and unablated myocardium and (2) calculate the lesion contrast (C) and contrast-to-noise ratio (CNR) in two-dimensional ARFI and conventional intracardiac echo images. In eight canine subjects, an ARFI imaging-electroanatomical mapping system was used to map right atrial ablation lesion sites and guide the acquisition of ARFI images at these sites before and after ablation. Readers of the ARFI images identified lesion sites with high sensitivity (90.2%) and specificity (94.3%) and the average measured ARFI-induced displacements were higher at unablated sites (11.23 ± 1.71 ?m) than at ablated sites (6.06 ± 0.94 ?m). The average lesion C (0.29 ± 0.33) and CNR (1.83 ± 1.75) were significantly higher for ARFI images than for spatially registered conventional B-mode images (C = ?0.03 ± 0.28, CNR = 0.74 ± 0.68). PMID:24554293

Eyerly, Stephanie A.; Bahnson, Tristram D.; Koontz, Jason I.; Bradway, David P.; Dumont, Douglas M.; Trahey, Gregg E.; Wolf, Patrick D.

2014-01-01

116

Acoustic radiation force impulse imaging of vulnerable plaques: a finite element method parametric analysis.  

PubMed

Plaque rupture is the most common cause of complications such as stroke and coronary heart failure. Recent histopathological evidence suggests that several plaque features, including a large lipid core and a thin fibrous cap, are associated with plaques most at risk for rupture. Acoustic Radiation Force Impulse (ARFI) imaging, a recently developed ultrasound-based elasticity imaging technique, shows promise for imaging these features noninvasively. Clinically, this could be used to distinguish vulnerable plaques, for which surgical intervention may be required, from those less prone to rupture. In this study, a parametric analysis using Finite Element Method (FEM) models was performed to simulate ARFI imaging of five different carotid artery plaques across a wide range of material properties. It was demonstrated that ARFI imaging could resolve the softer lipid pool from the surrounding, stiffer media and fibrous cap and was most dependent upon the stiffness of the lipid pool component. Stress concentrations due to an ARFI excitation were located in the media and fibrous cap components. In all cases, the maximum Von Mises stress was<1.2 kPa. In comparing these results with others investigating plaque rupture, it is concluded that while the mechanisms may be different, the Von Mises stresses imposed by ARFI imaging are orders of magnitude lower than the stresses associated with blood pressure. PMID:23122224

Doherty, Joshua R; Dumont, Douglas M; Trahey, Gregg E; Palmeri, Mark L

2013-01-01

117

A novel imaging technique based on the spatial coherence of backscattered waves: demonstration in the presence of acoustical clutter  

NASA Astrophysics Data System (ADS)

In the last 20 years, the number of suboptimal and inadequate ultrasound exams has increased. This trend has been linked to the increasing population of overweight and obese individuals. The primary causes of image degradation in these individuals are often attributed to phase aberration and clutter. Phase aberration degrades image quality by distorting the transmitted and received pressure waves, while clutter degrades image quality by introducing incoherent acoustical interference into the received pressure wavefront. Although significant research efforts have pursued the correction of image degradation due to phase aberration, few efforts have characterized or corrected image degradation due to clutter. We have developed a novel imaging technique that is capable of differentiating ultrasonic signals corrupted by acoustical interference. The technique, named short-lag spatial coherence (SLSC) imaging, is based on the spatial coherence of the received ultrasonic wavefront at small spatial distances across the transducer aperture. We demonstrate comparative B-mode and SLSC images using full-wave simulations that include the effects of clutter and show that SLSC imaging generates contrast-to-noise ratios (CNR) and signal-to-noise ratios (SNR) that are significantly better than B-mode imaging under noise-free conditions. In the presence of noise, SLSC imaging significantly outperforms conventional B-mode imaging in all image quality metrics. We demonstrate the use of SLSC imaging in vivo and compare B-mode and SLSC images of human thyroid and liver.

Dahl, Jeremy J.; Pinton, Gianmarco F.; Lediju, Muyinatu; Trahey, Gregg E.

2011-03-01

118

77 FR 321 - Section 4(f) Policy Paper  

Federal Register 2010, 2011, 2012, 2013

...FHWA-2011-0125] Section 4(f) Policy Paper AGENCY: Federal Highway Administration...comments on a draft Section 4(f) Policy Paper that will provide guidance on the procedures...of the proposed Section 4(f) Policy Paper is available for download and public...

2012-01-04

119

Passive element enriched photoacoustic computed tomography (PER PACT) for simultaneous imaging of acoustic propagation properties and light absorption.  

PubMed

We present a 'hybrid' imaging approach which can image both light absorption properties and acoustic transmission properties of an object in a two-dimensional slice using a computed tomography (CT) photoacoustic imager. The ultrasound transmission measurement method uses a strong optical absorber of small cross-section placed in the path of the light illuminating the sample. This absorber, which we call a passive element acts as a source of ultrasound. The interaction of ultrasound with the sample can be measured in transmission, using the same ultrasound detector used for photoacoustics. Such measurements are made at various angles around the sample in a CT approach. Images of the ultrasound propagation parameters, attenuation and speed of sound, can be reconstructed by inversion of a measurement model. We validate the method on specially designed phantoms and biological specimens. The obtained images are quantitative in terms of the shape, size, location, and acoustic properties of the examined heterogeneities. PMID:21369026

Jose, Jithin; Willemink, Rene G H; Resink, Steffen; Piras, Daniele; van Hespen, J C G; Slump, Cornelis H; Steenbergen, Wiendelt; van Leeuwen, Ton G; Manohar, Srirang

2011-01-31

120

Effect of MRI Acoustic Noise on Cerebral FDG Uptake in Simultaneous MR-PET Imaging  

PubMed Central

Integrated scanners capable of simultaneous PET and MRI data acquisition are now available for human use. Although the scanners’ manufacturers have made substantial efforts to understand and minimize the mutual electromagnetic interference between the two modalities, the potential physiological inference has not been evaluated. In this work, we have studied the influence of the acoustic noise produced by the MR gradients on brain FDG uptake in the Siemens MR-BrainPET prototype. While particular attention was paid to the primary auditory cortex (PAC), a brain-wide analysis was also performed. Methods The effects of the MR on the PET count rate and image quantification were first investigated in phantoms. Next, ten healthy volunteers underwent two simultaneous FDG-PET/MR scans in the supine position with the FDG injection occurring inside the MR-BrainPET, alternating between a “quiet” (control) environment in which no MR sequences were run during the FDG uptake phase (the first 40 minutes after radiotracer administration) and a “noisy” (test) case in which MR sequences were run for the entire time. Cortical and subcortical regions of interest (ROIs) were derived from the high-resolution morphological MR data using FreeSurfer. The changes in FDG uptake in the FreeSurfer-derived ROIs between the two conditions were analyzed from parametric and static PET images, and on a voxel-by-voxel basis using SPM8 and FreeSurfer. Results Only minimal to no electromagnetic interference was observed for most of the MR sequences tested, with a maximum drop in count rate of 1.5% and a maximum change in the measured activity of 1.1% in the corresponding images. The ROI-based analysis showed statistically significant increases in the right PAC in both the parametric (9.13±4.73%) and static (4.18±2.87%) images. SPM8 analysis showed no statistically significant clusters in any images when a p<0.05 (corrected) was used; however, a p<0.001 (uncorrected) resolved bilateral statistically significant clusters of increased FDG uptake in the area of the PAC for the parametric image (left: 8.37±1.55%, right: 8.20±1.17%), but only unilateral increase in the static image (left: 8.68±3.89%). Conclusion Although the operation of the BrainPET prototype is virtually unaffected by the MR scanner, the acoustic noise produced by the MR gradients causes a focal increase in FDG uptake in the PAC, which could affect the interpretation of pathological (or brain-activation related) changes in FDG uptake in this region, if the expected effects are of comparable amplitude. PMID:23462677

Abolmaali, Nasreddin; Arabasz, Grae; Guimaraes, Alexander R.; Catana, Ciprian

2013-01-01

121

Evaluation of real-time acoustical holography for breast imaging and biopsy guidance  

NASA Astrophysics Data System (ADS)

Ultrasound is an attractive modality for adjunctive characterization of certain breast lesions, but it is not considered specific for cancer and it is not recommended for screening. An imaging technique remarkably different from pulse-echo ultrasound, termed Optical SonographyTM (Advanced Diagnostics, Inc.), uses the through-transmission signal. The method was applied to breast examinations in 41 asymptomatic and symptomatic women ranging in age from 18 to 83 years to evaluate this imaging modality for detection and characterization of breast disease and normal tissue. This approach uses coherent sound and coherent light to produce real-time, large field-of-view images with pronounced edge definition in soft tissues of the body. The system patient interface was modified to improve coupling to the breast and bring the chest wall to within 3 cm of the sound beam. System resolution (full width half maximum of the line-spread function) was 0.5 mm for a swept-frequency beam centered at 2.7 MHz. Resolution degrades slightly in the periphery of the very large 15.2-cm field of view. Dynamic range of the reconstructed 'raw' images (no post processing) was 3000:1. Included in the study population were women with dense parenchyma, palpable ductal carcinoma in situ with negative mammography, superficial and deep fibroadenomas, and calcifications. Successful breast imaging was performed in 40 of 41 women. These images were then compared with images generated using conventional X-ray mammography and pulse-echo ultrasound. Margins of lesions and internal textures were particularly well defined and provided substantial contrast to fatty and dense parenchyma. In two malignant lesions, Optical SonographyTM appeared to approximate more closely tumor extent compared to mammography than pulse-echo sonography. These preliminary studies indicate the method has unique potential for detecting, differentiating, and guiding the biopsy of breast lesions using real-time acoustical holography.

Lehman, Constance D.; Andre, Michael P.; Fecht, Barbara A.; Johansen, Jennifer M.; Shelby, Ronald L.; Shelby, Jerod O.

1999-05-01

122

Acoustic radiation force impulse imaging of vulnerable plaques: a finite element method parametric analysis  

PubMed Central

Plaque rupture is the most common cause of complications such as stroke and coronary heart failure. Recent histopathological evidence suggests that several plaque features, including a large lipid core and a thin fibrous cap, are associated with plaques most at risk for rupture. Acoustic Radiation Force Impulse (ARFI) imaging, a recently developed ultrasound-based elasticity imaging technique, shows promise for imaging these features noninvasively. Clinically, this could be used to distinguish vulnerable plaques, for which surgical intervention may be required, from those less prone to rupture. In this study, a parametric analysis using Finite-Element Method (FEM) models was performed to simulate ARFI imaging of five different carotid artery plaques across a wide range of material properties. It was demonstrated that ARFI could resolve the softer lipid pool from the surrounding, stiffer media and fibrous cap and was most dependent upon the stiffness of the lipid pool component. Stress concentrations due to an ARFI excitation were located in the media and fibrous cap components. In all cases, the maximum Von Mises stress was < 1.2 kPa. In comparing these results with others investigating plaque rupture, it is concluded that while the mechanisms may be different, the Von Mises stresses imposed by ARFI are orders of magnitude lower than the stresses associated with blood pressure. PMID:23122224

Doherty, Joshua R.; Dumont, Douglas M.; Trahey, Gregg E.; Palmeri, Mark L.

2012-01-01

123

Evaluation of graft stiffness using acoustic radiation force impulse imaging after living donor liver transplantation.  

PubMed

Acoustic radiation force impulse (ARFI) imaging is an ultrasound-based modality to evaluate tissue stiffness using short-duration acoustic pulses in the region of interest. Virtual touch tissue quantification (VTTQ), which is an implementation of ARFI, allows quantitative assessment of tissue stiffness. Twenty recipients who underwent living donor liver transplantation (LDLT) for chronic liver diseases were enrolled. Graft types included left lobes with the middle hepatic vein and caudate lobes (n = 11), right lobes (n = 7), and right posterior segments (n = 2). They underwent measurement of graft VTTQ during the early post-LDLT period. The VTTQ value level rose after LDLT, reaching a maximum level on postoperative day 4. There were no significant differences in the VTTQ values between the left and right lobe graft types. Significant correlations were observed between the postoperative maximum value of VTTQ and graft volume-to-recipient standard liver volume ratio, portal venous flow to graft volume ratio, and post-LDLT portal venous pressure. The postoperative maximum serum alanine aminotransferase level and ascites fluid production were also significantly correlated with VTTQ. ARFI may be a useful diagnostic tool for the noninvasive and quantitative evaluation of the severity of graft dysfunction after LDLT. PMID:25203425

Ijichi, Hideki; Shirabe, Ken; Matsumoto, Yoshihiro; Yoshizumi, Tomoharu; Ikegami, Toru; Kayashima, Hiroto; Morita, Kazutoyo; Toshima, Takeo; Mano, Yohei; Maehara, Yoshihiko

2014-11-01

124

High-Resolution Acoustic-Radiation-Force-Impulse Imaging for Assessing Corneal Sclerosis  

PubMed Central

In ophthalmology, detecting the biomechanical properties of the cornea can provide valuable information about various corneal pathologies, including keratoconus and the phototoxic effects of ultraviolet radiation on the cornea. Also, the mechanical properties of the cornea can be used to evaluate the recovery from corneal refractive surgeries. Therefore, noninvasive and high-resolution estimation of the stiffness distribution in the cornea is important in ophthalmic diagnosis. The present study established a method for high-resolution acoustic-radiation-force-impulse (ARFI) imaging based on a dual-frequency confocal transducer in order to obtain a relative stiffness map, which was used to assess corneal sclerosis. An 11-MHz pushing element was used to induce localized displacements of tissue, which were monitored by a 48-MHz imaging element. Since the tissue displacements are directly correlated with the tissue elastic properties, the stiffness distribution in a tiny region of the cornea can be found by a mechanical B/D scan. The experimental system was verified using tissue-mimicking phantoms that included different geometric structures. Ex vivo cornea experiments were carried out using fresh porcine eyeballs. Corneas with localized sclerosis were created artificially by the injection of a formalin solution. The phantom experiments showed that the distributions of stiffness within different phantoms can be recognized clearly using ARFI imaging, and the measured lateral and axial resolutions of this imaging system were 177 and 153 ?m, respectively. The ex vivo experimental results from ARFI imaging showed that a tiny region of localized sclerosis in the cornea could be distinguished. All of the obtained results demonstrate that high-resolution ARFI imaging has considerable potential for the clinical diagnosis of corneal sclerosis. PMID:23584258

Shih, Cho-Chiang; Zhou, Qifa; Shung, K. Kirk

2013-01-01

125

Measuring soft tissue elasticity by monitoring surface acoustic waves using image plane digital holography  

NASA Astrophysics Data System (ADS)

The detection of tumors in soft tissues, such as breast cancer, is important to achieve at the earliest stages of the disease to improve patient outcome. Tumors often exhibit a greater elastic modulus compared to normal tissues. In this paper, we report our first study to measure elastic properties of soft tissues by mapping the surface acoustic waves (SAWs) with image plane digital holography. The experimental results show that the SAW velocity is proportional to the square root of elastic modulus over a range from 3.7-122kPa in homogeneous tissue phantoms, consistent with Rayleigh wave theory. This technique also permits detection of the interface of two-layer phantoms 10mm deep under surface and the interface depth by quantifying the SAW dispersion.

Li, Shiguang; Oldenburg, Amy L.

2011-03-01

126

Design and Numerical Evaluation of Off-Axis Aplanatic Straubel Mirror for Underwater Acoustic Imaging  

NASA Astrophysics Data System (ADS)

An aplanatic Straubel mirror was designed for underwater acoustic imaging. However, there was a problem in that incident sound waves coming into the aplanatic Straubel mirror were interrupted by a receiver array placed in front of the mirror. An off-axis Straubel mirror is proposed to solve this problem. In this study, an off-axis aplanatic Straubel mirror is designed and evaluated using numerical calculation to verify the feasibility of the off-axis design. Upon comparison of the off-axis and ordinary aplanatic Straubel mirrors, the off-axis mirror shows almost the same convergence property as the ordinary one when a receiver array exists. The off-axis aplanatic Straubel mirror is compared with an aplanatic Fresnel lens because this lens is not affected by the receiver. The results show that the off-axis mirror showed a smaller aberration than the aplanatic Fresnel lens at a wider angle of view.

Sato, Yuji; Mizutani, Koichi; Wakatsuki, Naoto; Nakamura, Toshiaki

2012-07-01

127

A Spinal Cord Window Chamber Model for In Vivo Longitudinal Multimodal Optical and Acoustic Imaging in a Murine Model  

PubMed Central

In vivo and direct imaging of the murine spinal cord and its vasculature using multimodal (optical and acoustic) imaging techniques could significantly advance preclinical studies of the spinal cord. Such intrinsically high resolution and complementary imaging technologies could provide a powerful means of quantitatively monitoring changes in anatomy, structure, physiology and function of the living cord over time after traumatic injury, onset of disease, or therapeutic intervention. However, longitudinal in vivo imaging of the intact spinal cord in rodent models has been challenging, requiring repeated surgeries to expose the cord for imaging or sacrifice of animals at various time points for ex vivo tissue analysis. To address these limitations, we have developed an implantable spinal cord window chamber (SCWC) device and procedures in mice for repeated multimodal intravital microscopic imaging of the cord and its vasculature in situ. We present methodology for using our SCWC to achieve spatially co-registered optical-acoustic imaging performed serially for up to four weeks, without damaging the cord or induction of locomotor deficits in implanted animals. To demonstrate the feasibility, we used the SCWC model to study the response of the normal spinal cord vasculature to ionizing radiation over time using white light and fluorescence microscopy combined with optical coherence tomography (OCT) in vivo. In vivo power Doppler ultrasound and photoacoustics were used to directly visualize the cord and vascular structures and to measure hemoglobin oxygen saturation through the complete spinal cord, respectively. The model was also used for intravital imaging of spinal micrometastases resulting from primary brain tumor using fluorescence and bioluminescence imaging. Our SCWC model overcomes previous in vivo imaging challenges, and our data provide evidence of the broader utility of hybridized optical-acoustic imaging methods for obtaining multiparametric and rich imaging data sets, including over extended periods, for preclinical in vivo spinal cord research. PMID:23516432

Maeda, Azusa; Conroy, Leigh; McMullen, Jesse D.; Silver, Jason I.; Stapleton, Shawn; Vitkin, Alex; Lindsay, Patricia; Burrell, Kelly; Zadeh, Gelareh; Fehlings, Michael G.; DaCosta, Ralph S.

2013-01-01

128

Imaging of Acoustically Coupled Oscillations Due to Flow Past a Shallow Cavity: Effect of Cavity Length Scale  

SciTech Connect

Flow-acoustic interactions due to fully turbulent inflow past a shallow axisymmetric cavity mounted in a pipe, which give rise to flow tones, are investigated using a technique of high-image-density particle image velocimetry in conjunction with unsteady pressure measurements. This imaging leads to patterns of velocity, vorticity, streamline topology, and hydrodynamic contributions to the acoustic power integral. Global instantaneous images, as well as time-averaged images, are evaluated to provide insight into the flow physics during tone generation. Emphasis is on the manner in which the streamwise length scale of the cavity alters the major features of the flow structure. These image-based approaches allow identification of regions of the unsteady shear layer that contribute to the instantaneous hydrodynamic component of the acoustic power, which is necessary to maintain a flow tone. In addition, combined image analysis and pressure measurements allow categorization of the instantaneous flow patterns that are associated with types of time traces and spectra of the fluctuating pressure. In contrast to consideration based solely on pressure spectra, it is demonstrated that locked-on tones may actually exhibit intermittent, non-phase-locked images, apparently due to low damping of the acoustic resonator. Locked-on flow tones (without modulation or intermittency), locked-on flow tones with modulation, and non-locked-on oscillations with short-term, highly coherent fluctuations are defined and represented by selected cases. Depending on which of these regimes occur, the time-averaged Q (quality)-factor and the dimensionless peak pressure are substantially altered.

P Oshkai; M Geveci; D Rockwell; M Pollack

2004-05-24

129

Experimental study on acoustic subwavelength imaging of holey-structured metamaterials by resonant tunneling.  

PubMed

A holey-structured metamaterial is proposed for near-field acoustic imaging beyond the diffraction limit. The structured lens consists of a rigid slab perforated with an array of cylindrical holes with periodically modulated diameters. Based on the effective medium approach, the structured lens is characterized by multilayered metamaterials with anisotropic dynamic mass, and an analytic model is proposed to evaluate the transmission properties of incident evanescent waves. The condition is derived for the resonant tunneling, by which evanescent waves can completely transmit through the structured lens without decaying. As an advantage of the proposed lens, the imaging frequency can be modified by the diameter modulation of internal holes without the change of the lens thickness in contrast to the lens due to the Fabry-Pérot resonant mechanism. In this experiment, the lens is assembled by aluminum plates drilled with cylindrical holes. The imaging experiment demonstrates that the designed lens can clearly distinguish two sources separated in the distance below the diffraction limit at the tunneling frequency. PMID:25234968

Su, Haijing; Zhou, Xiaoming; Xu, Xianchen; Hu, Gengkai

2014-04-01

130

In Vivo Study of Transverse Carpal Ligament Stiffness Using Acoustic Radiation Force Impulse (ARFI) Imaging  

PubMed Central

The transverse carpal ligament (TCL) forms the volar boundary of the carpal tunnel and may provide mechanical constraint to the median nerve, leading to carpal tunnel syndrome. Therefore, the mechanical properties of the TCL are essential to better understand the etiology of carpal tunnel syndrome. The purpose of this study was to investigate the in vivo TCL stiffness using acoustic radiation force impulse (ARFI) imaging. The shear wave velocity (SWV) of the TCL was measured using Virtual Touch IQTM software in 15 healthy, male subjects. The skin and the thenar muscles were also examined as reference tissues. In addition, the effects of measurement location and ultrasound transducer compression on the SWV were studied. The SWV of the TCL was dependent on the tissue location, with greater SWV values within the muscle-attached region than those outside of the muscle-attached region. The SWV of the TCL was significantly smaller without compression (5.21 ± 1.08 m/s) than with compression (6.62 ± 1.18 m/s). The SWV measurements of the skin and the thenar muscles were also affected by transducer compression, but to different extents than the SWV of the TCL. Therefore to standardize the ARFI imaging procedure, it is recommended that a layer of ultrasound gel be maintained to minimize the effects of tissue compression. This study demonstrated the feasibility of ARFI imaging for assessing the stiffness characteristics of the TCL in vivo, which has the potential to identify pathomechanical changes of the tissue. PMID:23861919

Shen, Zhilei Liu; Vince, D. Geoffrey; Li, Zong-Ming

2013-01-01

131

Intracardiac Acoustic Radiation Force Impulse (ARFI) and Shear Wave Imaging in Pigs with Focal Infarctions  

PubMed Central

Four pigs, three with focal infarctions in the apical intraventricular septum (IVS) and/or left ventricular free wall (LVFW), were imaged with an intracardiac echocardiography (ICE) transducer. Custom beam sequences were used to excite the myocardium with focused acoustic radiation force (ARF) impulses and image the subsequent tissue response. Tissue displacement in response to the ARF excitation was calculated with a phase-based estimator, and transverse wave magnitude and velocity were each estimated at every depth. The excitation sequence was repeated rapidly, either in the same location to generate 40 Hz M-Modes at a single steering angle, or with a modulated steering angle to synthesize 2-D displacement magnitude and shear wave velocity images at 17 points in the cardiac cycle. Both types of images were acquired from various views in the right and left ventricles, in and out of infarcted regions. In all animals, ARFI and SWEI estimates indicated diastolic relaxation and systolic contraction in non-infarcted tissues. The M-Mode sequences showed high beat-to-beat spatio-temporal repeatability of the measurements for each imaging plane. In views of noninfarcted tissue in the diseased animals, no significant elastic remodeling was indicated when compared to the control. Where available, views of infarcted tissue were compared to similar views from the control animal. In views of the LVFW, the infarcted tissue presented as stiff and non-contractile compared to the control. In a view of the IVS, no significant difference was seen between infarcted and healthy tissue, while in another view, a heterogeneous infarction was seen presenting itself as non-contractile in systole. PMID:25004538

Hollender, Peter; Bradway, David; Wolf, Patrick; Goswami, Robi; Trahey, Gregg

2013-01-01

132

Imaging velocity and attenuation anomalies in mining environments using Acoustic Emissions  

NASA Astrophysics Data System (ADS)

Imaging structural properties and monitoring fracturing processes in mining environments is of importance for mining exploitation. It is also helpful to characterize damages induced by mining activities, thus it is of primary interest for mining engineering and civil protection. Additionally, the development of improved monitoring and imaging methods is of great importance for salt deposits as potential reservoirs for CO2 sequestration. The analysis of Acoustic Emission (AE) and microseismicity data, which are routinely used in mining survey, is typically limited to estimate location of induced microcracks and seismicity. AE data will be here further analysed to obtain images of the seismic structure. We focus on an AE dataset recorded at the Morsleben salt mine, in Germany; the dataset contains more than 1 million events, recorded during a period of two months, with AE magnitudes spanning 5 units. Arrival times of first P and S onsets, as well as maximal amplitudes recorded for both seismic phases, are used to assess the seismic velocities and attenuation properties of the mining environment. Given the large size of the considered dataset, a spatial clustering of the events is first performed and a spatial homogeneous catalog of averaged "pseudoevents" is built. This new catalog is then used to provide first averaged images of the attenuation and velocity anomalies at specific depths. Results points to clear velocity and attenuation anomalies, which are correlated with the main structural features and the geometry of the salt body. The potential of the dataset for tomographic applications is investigated, both including synthetic simulations and considering real data. This study is funded by the project MINE, which is part of the R&D-Programme GEOTECHNOLOGIEN. The project MINE is funded by the German Ministry of Education and Research (BMBF), Grant of project BMBF03G0737.

Cesca, S.; Monna, S.; Kaiser, D.; Dahm, T.

2012-04-01

133

Acoustic Imaging of Microstructure and Evaluation of the Adhesive's Physical, Mechanical and Chemical Properties Changes at Different Cure States  

NASA Astrophysics Data System (ADS)

Epoxy thermoset adhesives transform during cure from liquid state into the highly cross-linked solid. Cure state of the material depends on condition of the reaction (temperature, pressure, time etc.) and resin/hardener ratio. It is known that the cure degree of the adhesive correlates with adhesion strength, which is critical for structural adhesives used in automotive, aerospace and marine industries. In this work, characterization of cure process of the adhesive with acoustic methods is presented. Evolution of the acoustic and elastic properties (attenuation, sound velocity, density, elastic moduli) during cure reaction was monitored in relation to the substantial physical and chemical changes of the material. These macro parameters of the adhesive were compared with the material's microstructure obtained by high-resolution acoustic microscopy technique in frequencies range of 50-400 MHz. Development of the microstructure of the adhesive as it cures at different conditions has been investigated. Appearance and development of the granular structure on the adhesive interface during cure reaction has been demonstrated. Acoustic images were analyzed by mathematical method to quantitatively characterize distribution of the adhesive's components. Statistical analysis of such images provides an accurate quantitative measure of the degree of cure of such samples. Research results presented in this paper can be useful as a basis for non-destructive evaluation of the adhesive materials

Severina, I. A.; Fabre, A. J.; Maeva, E. Yu.

134

High resolution imaging beyond the acoustic diffraction limit in deep tissue via ultrasound-switchable NIR fluorescence.  

PubMed

Fluorescence imaging in deep tissue with high spatial resolution is highly desirable because it can provide details about tissue's structural, functional, and molecular information. Unfortunately, current fluorescence imaging techniques are limited either in penetration depth (microscopy) or spatial resolution (diffuse light based imaging) as a result of strong light scattering in deep tissue. To overcome this limitation, we developed an ultrasound-switchable fluorescence (USF) imaging technique whereby ultrasound was used to switch on/off the emission of near infrared (NIR) fluorophores. We synthesized and characterized unique NIR USF contrast agents. The excellent switching properties of these agents, combined with the sensitive USF imaging system developed in this study, enabled us to image fluorescent targets in deep tissue with spatial resolution beyond the acoustic diffraction limit. PMID:24732947

Pei, Yanbo; Wei, Ming-Yuan; Cheng, Bingbing; Liu, Yuan; Xie, Zhiwei; Nguyen, Kytai; Yuan, Baohong

2014-01-01

135

Quantitative enhancement of fatigue crack monitoring by imaging surface acoustic wave reflection in a space-cycle-load domain  

SciTech Connect

The surface wave acoustic method is applied to the in-situ monitoring of fatigue crack initiation and evolution on tension specimens. A small low-frequency periodic loading is also applied, resulting in a nonlinear modulation of reflected pulses. The acoustic wave reflections are collected for: each experimental cycle; a range of applied tension and modulation load levels; and a range of spatial propagation positions, and are presented in image form to aid pattern identification. Salient features of the image are then extracted and processed to evaluate the initiation time of the crack and its subsequent size evolution until sample failure. Additionally, a method for enhancing signal to noise ratio in Ti-6242 alloy samples is demonstrated.

Connolly, G. D.; Rokhlin, S. I. [Ohio State University, Edison Joining Technology Center, 1248 Arthur E Adams Drive, Columbus, OH 43221 (United States)

2011-06-23

136

Bats use a neuronally implemented computational acoustic model to form sonar images.  

PubMed

This paper reexamines neurophysiological results from echolocating big brown bats to propose a new perspective on FM biosonar processing in the auditory system. Individual auditory neurons are frequency-tuned and respond to brief, 2-10 ms FM sweeps with an average of one spike per sound to register their tuned frequencies, to detect echo arrival, or to register a local null in the echo spectrum. When initiated by the broadcast, these responses comprise a cascade of single spikes distributed across time in neurons tuned to different frequencies that persists for 30-50 ms, long after the sound has ended. Their progress mirrors the broadcast's propagation away from the bat and the return of echoes for distances out to 5-8 m. Each returning echo evokes a similar pattern of single spikes that coincide with ongoing responses to the broadcast to register the target's distance and shape. The hypothesis advanced here is that this flow of responses over time acts as an internal model of sonar acoustics that the bat executes using neuronal computations distributed across many neurons to accumulate a dynamic image of the bat's surroundings. PMID:22436892

Simmons, James A

2012-04-01

137

Cerebellar encephalomalacia on magnetic resonance imaging after removal of acoustic tumor  

Microsoft Academic Search

MRI is widely used for postoperative surveillance of patients undergoing surgery for removal of acoustic neuroma. The purpose of this study was to investigate the frequency and pattern of postoperative changes in the cerebellum and brain stem on MRI after removal of acoustic neuroma. A retrospective study was conducted in 30 consecutive patients who underwent postoperative MRI between 1994 and

P. BORDURE; G. M. O'DONOGHUE; T. JASPAN; M. DENUNZIO

1999-01-01

138

EEE 445 Microwaves (4) [F] Course (Catalog) Description  

E-print Network

EEE 445 Microwaves (4) [F] Course (Catalog) Description: Waveguides; circuit theory for waveguiding systems; microwave devices, systems, and energy sources; striplines and microstrips; impedance matching, Microwave Engineering, Addison-Wesley, 1990. Supplemental Materials: - R.S. Elliott, An Introduction

Zhang, Junshan

139

Structural, magnetic, and energetic properties of Na2FePO4F, Li2FePO4F, NaFePO4F, and LiFePO4F from ab initio calculations  

NASA Astrophysics Data System (ADS)

In this paper, we report on Na2FePO4F and Li2FePO4F, which are materials that are used as cathodes in batteries, using density functional theory with the LDA, LDA+U, GGA, or GGA+U approximations. Specifically, we study their crystal structure, electronic structure, and magnetic properties and provide similar information about the intermediate compounds LiFePO4F and NaFePO4F. Finally, the intercalation voltages of the corresponding batteries are calculated using various exchange-correlation approximations and conclusions are drawn about which one is the most suitable to use for the study of this class of materials.

Ramzan, M.; Lebègue, S.; Larsson, P.; Ahuja, R.

2009-08-01

140

Diagnostic Value of Elastography Using Acoustic Radiation Force Impulse Imaging and Strain Ratio for Breast Tumors  

PubMed Central

Purpose The aim of this study was to determine whether the combination of B-mode ultrasonography (BUS), acoustic radiation force impulse (ARFI) elastography, and strain ratio (SR) provides better diagnostic performance of breast lesion differentiation than BUS alone. Methods ARFI elastography and SR evaluations were performed on patients with 157 breast lesions diagnosed by BUS from June to September 2013. BUS images were classified according to the Breast Imaging-Reporting and Data System. ARFI elastography was performed using Virtual Touch™ tissue imaging (VTI) and Virtual Touch™ tissue quantification (VTQ). In VTI mode, we evaluated the color-mapped patterns of the breast lesion and surrounding tissue. The lesions were classified into five categories by elasticity score. In VTQ mode, each lesion was assessed using shear wave velocity (SWV) measurements. SR was calculated from the lesion and comparable lateral fatty tissue. We compared the diagnostic performance of BUS alone and the combination of BUS, ARFI elastography, and SR evaluations. Results Among the 157 lesions, 40 were malignant and 117 were benign. The mean elasticity score (3.7±1.0 vs. 1.6±0.8, p<0.01), SWV (4.23±1.09 m/sec vs. 2.22±0.88 m/sec, p<0.01), and SR (5.69±1.63 vs. 2.69±1.40, p<0.01) were significantly higher for malignant lesions than benign lesions. The results for BUS combined with ARFI elastography and SR values were 97.5% sensitivity, 92.3% specificity, 93.6% accuracy, a 79.6% positive predictive value (PPV), and a 99.1% negative predictive value. The combination of the 3 radiologic examinations yielded superior specificity, accuracy, and PPV compared to BUS alone (p<0.01 for each). Conclusion ARFI elastography and SR evaluations showed significantly different mean values for benign and malignant lesions. Moreover, these two modalities complemented BUS and improved the diagnostic performance of breast lesion detection. Therefore, ARFI elastography and SR evaluations can be used as complementary modalities to make more accurate breast lesion diagnoses. PMID:24744801

Kim, Yoon Seok; Park, Jung Gu; Kim, Beom Su; Lee, Chung Han

2014-01-01

141

Pou4f1 and Pou4f2 Are Dispensable for the Long-Term Survival of Adult Retinal Ganglion Cells in Mice  

PubMed Central

Purpose To investigate the role of Pou4f1 and Pou4f2 in the survival of adult retinal ganglion cells (RGCs). Methods Conditional alleles of Pou4f1 and Pou4f2 were generated (Pou4f1loxP and Pou4f2loxP respectively) for the removal of Pou4f1 and Pou4f2 in adult retinas. A tamoxifen-inducible Cre was used to delete Pou4f1 and Pou4f2 in adult mice and retinal sections and flat mounts were subjected to immunohistochemistry to confirm the deletion of both alleles and to quantify the changes in the number of RGCs and other retinal neurons. To determine the effect of loss of Pou4f1 and Pou4f2 on RGC survival after axonal injury, controlled optic nerve crush (CONC) was performed and RGC death was assessed. Results Pou4f1 and Pou4f2 were ablated two weeks after tamoxifen treatment. Retinal interneurons and Müller glial cells are not affected by the ablation of Pou4f1 or Pou4f2 or both. Although the deletion of both Pou4f1 and Pou4f2 slightly delays the death of RGCs at 3 days post-CONC in adult mice, it does not affect the cell death progress afterwards. Moreoever, deletion of Pou4f1 or Pou4f2 or both has no impact on the long-term viability of RGCs at up to 6 months post-tamoxifen treatment. Conclusion Pou4f1 and Pou4f2 are involved in the acute response to damage to RGCs but are dispensable for the long-term survival of adult RGC in mice. PMID:24736625

Huang, Liang; Hu, Fang; Xie, Xiaoling; Harder, Jeffery; Fernandes, Kimberly; Zeng, Xiang-yun; Libby, Richard; Gan, Lin

2014-01-01

142

High-speed imaging, acoustic features, and aeroacoustic computations of jet noise from Strombolian (and Vulcanian) explosions  

NASA Astrophysics Data System (ADS)

imaging of explosive eruptions at Stromboli (Italy), Fuego (Guatemala), and Yasur (Vanuatu) volcanoes allowed visualization of pressure waves from seconds-long explosions. From the explosion jets, waves radiate with variable geometry, timing, and apparent direction and velocity. Both the explosion jets and their wave fields are replicated well by numerical simulations of supersonic jets impulsively released from a pressurized vessel. The scaled acoustic signal from one explosion at Stromboli displays a frequency pattern with an excellent match to those from the simulated jets. We conclude that both the observed waves and the audible sound from the explosions are jet noise, i.e., the typical acoustic field radiating from high-velocity jets. Volcanic jet noise was previously quantified only in the infrasonic emissions from large, sub-Plinian to Plinian eruptions. Our combined approach allows us to define the spatial and temporal evolution of audible jet noise from supersonic jets in small-scale volcanic eruptions.

Taddeucci, J.; Sesterhenn, J.; Scarlato, P.; Stampka, K.; Del Bello, E.; Pena Fernandez, J. J.; Gaudin, D.

2014-05-01

143

Acoustic radiation force impulse imaging (ARFI) on an IVUS circular array.  

PubMed

Our long-term goal is the detection and characterization of vulnerable plaque in the coronary arteries of the heart using intravascular ultrasound (IVUS) catheters. Vulnerable plaque, characterized by a thin fibrous cap and a soft, lipid-rich necrotic core is a precursor to heart attack and stroke. Early detection of such plaques may potentially alter the course of treatment of the patient to prevent ischemic events. We have previously described the characterization of carotid plaques using external linear arrays operating at 9 MHz. In addition, we previously modified circular array IVUS catheters by short-circuiting several neighboring elements to produce fixed beamwidths for intravascular hyperthermia applications. In this paper, we modified Volcano Visions 8.2 French, 9 MHz catheters and Volcano Platinum 3.5 French, 20 MHz catheters by short-circuiting portions of the array for acoustic radiation force impulse imaging (ARFI) applications. The catheters had an effective transmit aperture size of 2 mm and 1.5 mm, respectively. The catheters were connected to a Verasonics scanner and driven with pushing pulses of 180 V p-p to acquire ARFI data from a soft gel phantom with a Young's modulus of 2.9 kPa. The dynamic response of the tissue-mimicking material demonstrates a typical ARFI motion of 1 to 2 microns as the gel phantom displaces away and recovers back to its normal position. The hardware modifications applied to our IVUS catheters mimic potential beamforming modifications that could be implemented on IVUS scanners. Our results demonstrate that the generation of radiation force from IVUS catheters and the development of intravascular ARFI may be feasible. PMID:24554291

Patel, Vivek; Dahl, Jeremy J; Bradway, David P; Doherty, Joshua R; Lee, Seung Yun; Smith, Stephen W

2014-04-01

144

Using auditory classification images for the identification of fine acoustic cues used in speech perception  

PubMed Central

An essential step in understanding the processes underlying the general mechanism of perceptual categorization is to identify which portions of a physical stimulation modulate the behavior of our perceptual system. More specifically, in the context of speech comprehension, it is still a major open challenge to understand which information is used to categorize a speech stimulus as one phoneme or another, the auditory primitives relevant for the categorical perception of speech being still unknown. Here we propose to adapt a method relying on a Generalized Linear Model with smoothness priors, already used in the visual domain for the estimation of so-called classification images, to auditory experiments. This statistical model offers a rigorous framework for dealing with non-Gaussian noise, as it is often the case in the auditory modality, and limits the amount of noise in the estimated template by enforcing smoother solutions. By applying this technique to a specific two-alternative forced choice experiment between stimuli “aba” and “ada” in noise with an adaptive SNR, we confirm that the second formantic transition is key for classifying phonemes into /b/ or /d/ in noise, and that its estimation by the auditory system is a relative measurement across spectral bands and in relation to the perceived height of the second formant in the preceding syllable. Through this example, we show how the GLM with smoothness priors approach can be applied to the identification of fine functional acoustic cues in speech perception. Finally we discuss some assumptions of the model in the specific case of speech perception. PMID:24379774

Varnet, Léo; Knoblauch, Kenneth; Meunier, Fanny; Hoen, Michel

2013-01-01

145

A Novel Application of Time Reversed Acoustics: Salt Dome Flank Imaging Using Walk Away VSP Surveys  

E-print Network

In the past few years, there has been considerable research and interest in a topic known by various names, such as Time Reverse Acoustics (TRA), Time Reverse Mirrors (TRM), and Time Reverse Cavities (TRC), which exploits ...

Hoop, Martijn de

2005-01-01

146

Imaging the Permeability Structure of a Limestone Aquifer by Crosswell Acoustic Tomography.  

National Technical Information Service (NTIS)

A narrow-band pseudorandom binary sequence (PRBS) code was used to generate an acoustic pulse that approximates a single laser-like frequency. Measurements of crosswell tomography under a Florida limestone aquifer were made using four different PRBS frequ...

T. Yamamoto, T. Nye, M. Kuru

1995-01-01

147

An acoustic pyrometer system for tomographic thermal imaging in power plant boilers  

Microsoft Academic Search

The paper presents an acoustic pyrometry method for the reconstruction of temperature maps inside power plant boilers. It is based on measuring times-of-flight of acoustic waves along a number of straight paths in a cross-section of the boiler; via an integral relationship, these times depend on the temperature of the gaseous medium along the paths. On this basis, 2D temperature

Mauro Bramanti; Emanuele A. Salerno; Anna Tonazzini; Sauro Pasini; Antonio Gray

1996-01-01

148

Application of pulse compression signal processing techniques to electromagnetic acoustic transducers for noncontact thickness measurements and imaging  

SciTech Connect

A pair of noncontact Electromagnetic Acoustic Transducers (EMATs) has been used for thickness measurements and imaging of metallic plates. This was performed using wide bandwidth EMATs and pulse-compression signal processing techniques, using chirp excitation. This gives a greatly improved signal-to-noise ratio for air-coupled experiments, increasing the speed of data acquisition. A numerical simulation of the technique has confirmed the performance. Experimental results indicate that it is possible to perform noncontact ultrasonic imaging and thickness gauging in a wide range of metal plates. An accuracy of up to 99% has been obtained for aluminum, brass, and copper samples. The resolution of the image obtained using the pulse compression approach was also improved compared to a transient pulse signal from conventional pulser(receiver). It is thus suggested that the combination of EMATs and pulse compression can lead to a wide range of online applications where fast time acquisition is required.

Ho, K.S.; Gan, T.H.; Billson, D.R.; Hutchins, D.A. [School of Engineering, University of Warwick, Coventry, CV4 7AL (United Kingdom)

2005-05-15

149

IMAGING CONCERT HALL ACOUSTICS USING VISUAL AND AUDIO CAMERAS Adam O'Donovan, Ramani Duraiswami and Dmitry Zotkin  

E-print Network

varies significantly as source and receiver locations change. Spherical microphone arrays provide microphone array beamformer steered in all directions to create central projection to create acoustic Center in College Park, MD. Index Terms-- spherical microphone arrays, room acoustics, acoustical camera

Zotkin, Dmitry N.

150

Imaging Ripples on Phononic Crystals Reveals Acoustic Band Structure and Bloch Harmonics  

NASA Astrophysics Data System (ADS)

Broadband surface phonon wave packets on a phononic crystal made up of a microstructured line pattern are tracked in two dimensions and in real time with an ultrafast optical technique. The eigenmode distribution and the 2D acoustic band structure are obtained from spatiotemporal Fourier transforms of the data up to 1 GHz. We find stop bands at the zone boundaries for both leaky-longitudinal and Rayleigh waves, and show how the structure of individual acoustic eigenmodes in k space depends on Bloch harmonics and on mode coupling.

Profunser, Dieter M.; Wright, Oliver B.; Matsuda, Osamu

2006-08-01

151

Acoustic profiles and images of the Palos Verdes margin: Implications concerning deposition from the White's Point outfall  

USGS Publications Warehouse

Subbottom profiles and sidescan-sonar images collected on and around the Palos Verdes Shelf show a surficial deposit interpreted to contain effluent from the White's Point diffusers, as well as showing several geologic features that affect the deposit's distribution. The effluent-affected deposit is visible in high-resolution subbottom profiles on the shelf and the adjacent San Pedro basin slope to water depths of 170 m. It has a maximum thickness of 75 cm and was mapped acoustically over an area of 10.8 km2, which encompasses a volume of about 3.2 million m3. The deposit's basal reflector is acoustically distinct over most of the mapped area. implying that the deposit has not been extensively mixed across its base, perhaps being relatively free of reworking since its initial deposition. Nearshore, the basal reflector is weak and fades away toward land, which could result from syndepositional intermixing of coarse native sediment (particularly from the Portuguese Bend landslide) with effluent in the high-energy nearshore zone, or postdepositionally by physical (wave) or biological mixing across the interface. The geometry of the deposit implies that effluent is dispersed primarily in a northwesterly and seaward direction from the diffusers. Dispersal across the shelf break is in some places strongly affected by topography, particularly by submarine canyons. The deposit overlies stratified and unstratified Quaternary sediment, up to 30m thick, that in turn overlies the irregular erosional surface of deformed Miocene bedrock that crops out in places on the shelf and upper basin slope. The effluent-affected deposit rests on potentially unstable landslide deposits on the San Pedro basin slope. The acoustic profiles and side-scan images show evidence for active and inactive vents, probably of hot water and gas, some of which are within the boundary of the effluent-affected sediment deposit and could disrupt it if seepage occurs. ?? 2002 Elsevier Science Ltd. All rights reserved.

Hampton, M.A.; Karl, Herman A.; Murray, C.J.

2002-01-01

152

Remote acoustic imaging of the plume from a submarine spring in an arctic fjord.  

PubMed

Acoustic backscatter observations at 200 kilohertz were made of the buoyant plume from a submarine spring at a depth of 47 meters in Cambridge Fiord, Baffin Island. Vertical velocities of up to 37 centimeters per second are inferred from the ascent rates of discrete scattering structures in the plume. PMID:17782423

Hay, A E

1984-09-14

153

Acoustic neuroma  

MedlinePLUS

Vestibular schwannoma; Tumor - acoustic; Cerebellopontine angle tumor; Angle tumor ... Acoustic neuromas have been linked with the genetic disorder neurofibromatosis type 2 (NF2). Acoustic neuromas are uncommon.

154

Applications of Lorentz force in medical acoustics: Lorentz force hydrophone, Lorentz Force Electrical Impedance Tomography, Imaging of shear waves induced by Lorentz force  

E-print Network

The ability of the Lorentz force to link a mechanical displacement to an electrical current presents a strong interest for medical acoustics, and three applications were studied in this thesis. In the first part of this work, a hydrophone was developed for mapping the particle velocity of an acoustic field. This hydrophone was constructed using a thin copper wire and an external magnetic field. A model was elaborated to determine the relationship between the acoustic pressure and the measured electrical current, which is induced by Lorentz force when the wire vibrates in the acoustic field of an ultrasound transducer. The built prototype was characterized and its spatial resolution, frequency response, sensitivity, robustness and directivity response were investigated. An imaging method called Lorentz Force Electrical Impedance Tomography was also studied. In this method, a biological tissue is vibrated by ultrasound in a magnetic field, which induces an electrical current by Lorentz force. The electrical imp...

Grasland-Mongrain, Pol

2014-01-01

155

Multiscale monitoring of interface failure of brittle coating/ductile substrate systems: A non-destructive evaluation method combined digital image correlation with acoustic emission  

NASA Astrophysics Data System (ADS)

In this paper, we proposed a non-destructive evaluation method combined digital image correlation with acoustic emission techniques. The method was used to in situ monitor interface failure and internal damage of brittle coating/ductile substrate systems with different size scales. The results show that there is a good relationship between digital image correlation and acoustic emission signals, which can be applied to judge cracking formation and coating delamination and to determine fracture toughness of a thermal barrier coating system subjected to bending.

Mao, W. G.; Wu, D. J.; Yao, W. B.; Zhou, M.; Lu, C.

2011-10-01

156

The Acoustic Lens Design and in Vivo Use of a Multifunctional Catheter Combining Intracardiac Ultrasound Imaging and Electrophysiology Sensing  

PubMed Central

A multifunctional 9F intracardiac imaging and electrophysiology mapping catheter was developed and tested to help guide diagnostic and therapeutic intracardiac electrophysiology (EP) procedures. The catheter tip includes a 7.25-MHz, 64-element, side-looking phased array for high resolution sector scanning. Multiple electrophysiology mapping sensors were mounted as ring electrodes near the array for electrocardiographic synchronization of ultrasound images. The catheter array elevation beam performance in particular was investigated. An acoustic lens for the distal tip array designed with a round cross section can produce an acceptable elevation beam shape; however, the velocity of sound in the lens material should be approximately 155 m/s slower than in tissue for the best beam shape and wide bandwidth performance. To help establish the catheter’s unique ability for integration with electrophysiology interventional procedures, it was used in vivo in a porcine animal model, and demonstrated both useful intracardiac echocardiographic visualization and simultaneous 3-D positional information using integrated electroanatomical mapping techniques. The catheter also performed well in high frame rate imaging, color flow imaging, and strain rate imaging of atrial and ventricular structures. PMID:18407850

Stephens, Douglas N.; Cannata, Jonathan; Liu, Ruibin; Zhao, Jian Zhong; Shung, K. Kirk; Nguyen, Hien; Chia, Raymond; Dentinger, Aaron; Wildes, Douglas; Thomenius, Kai E.; Mahajan, Aman; Shivkumar, Kalyanam; Kim, Kang; O'Donnell, Matthew; Sahn, David

2009-01-01

157

Positive Ions in RF Discharge Plasmas of C4F8/Ar and C4F8/O2 Mixtures  

NASA Astrophysics Data System (ADS)

Discharge plasmas of C4F8/Ar and C4F8/O2 mixtures were investigated at a frequency of 13.56 MHz and a power of 34 W and at a pressure of 50 mTorr. Discharge-sustaining voltages vary almost monotonically with the gas mixing ratio. The major positive ions in C4F8/Ar discharge are C2F4+, CF3+ and Ar+. The ion count ratio of CF+ is the most intense among the positive ions in the CF system at a large Ar mixing ratio. From the variations of the ion count ratio of CFx+ (x=0 3), these ions seem to be produced partly by the electron-impact ionization of radicals generated from fluorocarbon films. In C4F8/O2 discharge, the major positive ions are C2F4+, CF3+, CO+ and O2+. The intensity ratios of ionic species vary as a function of gas mixing ratio. The ion count ratio of CO+, COF+ and COF2+ reach a maximum at an O2 mixing ratio of about 50%, and the ion count ratio of CO+ is much higher than that of O2+. This seems to suggest some secondary collision processes that occur in the discharge plasma.

Hirose, Yuji; Ishikawa, Itsuo; Sasaki, Shinya; Nagaseki, Kazuya; Saito, Yukinori; Suganomata, Shinji

1998-10-01

158

Acoustic radiation force impulse imaging for real-time observation of lesion development during radiofrequency ablation procedures  

NASA Astrophysics Data System (ADS)

When performing radiofrequency ablation (RFA) procedures, physicians currently have little or no feedback concerning the success of the treatment until follow-up assessments are made days to weeks later. To be successful, RFA must induce a thermal lesion of sufficient volume to completely destroy a target tumor or completely isolate an aberrant cardiac pathway. Although ultrasound, computed tomography (CT), and CT-based fluoroscopy have found use in guiding RFA treatments, they are deficient in giving accurate assessments of lesion size or boundaries during procedures. As induced thermal lesion size can vary considerably from patient to patient, the current lack of real-time feedback during RFA procedures is troublesome. We have developed a technique for real-time monitoring of thermal lesion size during RFA procedures utilizing acoustic radiation force impulse (ARFI) imaging. In both ex vivo and in vivo tissues, ARFI imaging provided better thermal lesion contrast and better overall appreciation for lesion size and boundaries relative to conventional sonography. The thermal safety of ARFI imaging for use at clinically realistic depths was also verified through the use of finite element method models. As ARFI imaging is implemented entirely on a diagnostic ultrasound scanner, it is a convenient, inexpensive, and promising modality for monitoring RFA procedures in vivo.

Fahey, Brian J.; Trahey, Gregg E.

2005-04-01

159

Comparison of Ion Chemistries in Octafluoro-2-butene (2-C4F8) and in Octfluorocyclobutane (c-C4F8)  

NASA Astrophysics Data System (ADS)

2-C4F8 is one of the promising candidates to replace c-C4F8 that has been widely used for dielectric etching but is not environmentally friendly. In this study we have investigated electron impact ionization and ion-molecule reactions of 2-C4F8 using Fourier transform mass spectrometry (FTMS), and compared the results with those of c-C4F8 we have studied previously. Electron impact ionization of 2-C4F8 produces 15 ionic species including C4F7,8^+, C3F3,5,6^+, C2F4^+ and CF1-3^+ as the major ions. The total ionization cross section of 2-C4F8 reaches a maximum of 1.8x10-15 cm^2 at 90 eV. The ionization is dominated by the channel forming the parent ion C4F8^+ from 12 to 18 eV, and by the channel forming C3F5^+ from 18 to 70 eV. After 70 eV, CF3^+ becomes the dominant product ion. Among the major ions generated from the electron impact ionization of 2-C4F8, only CF^+, CF2^+ and CF3^+ are found to react with 2-C4F8, via F^- abstraction or charge transfer mechanism. The charge transfer reaction of Ar^++2-C4F8 produces primarily C4F7^+.

Jiao, Charles; Dejoseph, Charles; Garscadden, Alan

2007-10-01

160

Investigation of the Near-Field Acoustic and Flow Properties of Imperfectly Expanded Supersonic Jets using Particle Image Velocimetry  

NASA Astrophysics Data System (ADS)

The flow fields of imperfectly Expanded Supersonic Jets from conical CD nozzles are investigated by Particle Image Velocimetry. This nozzle geometry represents the exhaust nozzles on high-performance military engines. The results are compared with shadowgraph to bring out the details of the highly accelerated regions where seed particles may lag behind the flow, viz. the shocks and Prandtl-Meyer fans. Nozzles with three area ratios are examined over a wide range of under- and over-expanded conditions as well as the design conditions for each nozzle. It is found that this type of nozzle is not shock free at the design condition due to the sharp change of the geometry in the throat area. Both near-field and far-field acoustic measurements are presented. Flow-field and near-field acoustic measurements are compared with Numerical simulations in the accompanying presentation by Liu, Kailasanath and Ramamurti. The distributions of the centerline static pressure and noise spectra are in good agreement with the corresponding experimental data.

Gutmark, Ephraim; Munday, David; Liu, Junhui; Kailasanath, K.

2008-11-01

161

A new matlab® library to interactively analyze logging data and borehole wall images and to recenter borehole acoustic images  

Microsoft Academic Search

Observations acquired downhole are basically of two types : standard logs and borehole wall images, i.e. scalars versus depth and images versus depth. While many freeware programs can deal with standard logs, very few are able to treat simultaneously and interactively both scalars and images, including standard treatments commonly applied to such data. The developed matlab library offers such a

P. Pinettes

2003-01-01

162

IEEE TRANSACTIONS ON IMAGE PROCESSING, VOL. 18, NO. 6, JUNE 2009 1203 Opti-Acoustic Stereo Imaging: On System Calibration  

E-print Network

the performance in compar- ison with the processing of images from each sensor, alone. This multisensor fusion estimation from noisy image measure- ments. The recursive 3-D reconstruction method utilized as initial strategy has been explored for registering image data to known 3-D object models [5], and to automat

Reif, Rafael

163

1736 IEEE TRANSACTIONS ON ACOUSTICS,SPEECH, ANDSIGNAL PROCESSING, VOL. ASSP-35,NO. 12, DECEMBER 1987 Two-Dimensional Block Kalman Filtering for Image  

E-print Network

1736 IEEE TRANSACTIONS ON ACOUSTICS,SPEECH, ANDSIGNAL PROCESSING, VOL. ASSP-35,NO. 12, DECEMBER is introduced. This structure is derived by arranging a vector autoregressive (AR) model with a causal quarter image which may be due to sensors, quan- tization effects, and transmission media,etc.The noise which

Azimi-Sadjadi, Mahmood R.

164

Compressive sensing beamforming based on covariance for acoustic imaging with noisy measurements.  

PubMed

Compressive sensing, a newly emerging method from information technology, is applied to array beamforming and associated acoustic applications. A compressive sensing beamforming method (CSB-II) is developed based on sampling covariance matrix, assuming spatially sparse and incoherent signals, and then examined using both simulations and aeroacoustic measurements. The simulation results clearly show that the proposed CSB-II method is robust to sensing noise. In addition, aeroacoustic tests of a landing gear model demonstrate the good performance in terms of resolution and sidelobe rejection. PMID:24181989

Zhong, Siyang; Wei, Qingkai; Huang, Xun

2013-11-01

165

Reducing the Impacts of Hydroelectric Dams on Juvenile Anadromous Fishes: Bioengineering Evaluations Using Acoustic Imaging in the Columbia River, USA  

SciTech Connect

Dams impact the survival of juvenile anadromous fishes by obstructing migration corridors, lowering water quality, delaying migrations, and entraining fish in turbine discharge. To reduce these impacts, structural and operational modifications to dams— such as voluntary spill discharge, turbine intake guidance screens, and surface flow outlets—are instituted. Over the last six years, we have used acoustic imaging technology to evaluate the effects of these modifications on fish behavior, passage rates, entrainment zones, and fish/flow relationships at hydroelectric projects on the Columbia River. The imaging technique has evolved from studies documenting simple movement patterns to automated tracking of images to merging and analysis with concurrent hydraulic data. This chapter chronicles this evolution and shows how the information gleaned from the scientific evaluations has been applied to improve passage conditions for juvenile salmonids. We present data from Bonneville and The Dalles dams that document fish behavior and entrainment zones at sluiceway outlets (14 to 142 m3/s), fish passage rates through a gap at a turbine intake screen, and the relationship between fish swimming effort and hydraulic conditions. Dam operators and fisheries managers have applied these data to support decisions on operational and structural changes to the dams for the benefit of anadromous fish populations in the Columbia River basin.

Johnson, Gary E.; Ploskey, Gene R.; Hedgepeth, J.; Khan, Fenton; Mueller, Robert P.; Nagy, William T.; Richmond, Marshall C.; Weiland, Mark A.

2008-07-29

166

Wavefront modulation and subwavelength diffractive acoustics with an acoustic metasurface.  

PubMed

Metasurfaces are a family of novel wavefront-shaping devices with planar profile and subwavelength thickness. Acoustic metasurfaces with ultralow profile yet extraordinary wave manipulating properties would be highly desirable for improving the performance of many acoustic wave-based applications. However, designing acoustic metasurfaces with similar functionality to their electromagnetic counterparts remains challenging with traditional metamaterial design approaches. Here we present a design and realization of an acoustic metasurface based on tapered labyrinthine metamaterials. The demonstrated metasurface can not only steer an acoustic beam as expected from the generalized Snell's law, but also exhibits various unique properties such as conversion from propagating wave to surface mode, extraordinary beam-steering and apparent negative refraction through higher-order diffraction. Such designer acoustic metasurfaces provide a new design methodology for acoustic signal modulation devices and may be useful for applications such as acoustic imaging, beam steering, ultrasound lens design and acoustic surface wave-based applications. PMID:25418084

Xie, Yangbo; Wang, Wenqi; Chen, Huanyang; Konneker, Adam; Popa, Bogdan-Ioan; Cummer, Steven A

2014-01-01

167

A Multiview, Multimodal Fusion Framework for Classifying Small Marine Animals with an Opto-Acoustic Imaging System  

E-print Network

support vector machines with softmax outputs to classify either acoustical or optical features. Outputs] and marine animal tracking [6], or acoustic sensors for fish classifica- tion [7, 8, 9]. Advantages using acoustic sensors, multiview systems have been shown to improve estimates of animal size [16

Jaffe, Jules

168

ACOUSTICAL IMAGING AND MECHANICAL PROPERTIES OF SOFT ROCK AND MARINE SEDIMENTS  

SciTech Connect

Three major goals were accomplished during this phase. First, a study was completed of the effects of stress-induced changes in anisotropic elastic moduli in sandstone. Second, a new method for measuring the anisotropic poroelastic moduli from acoustic data was developed. Third, a series of triaxial experiments were conducted on unconsolidated sands to identify pressure/stress conditions where liquefaction occurs under high confining pressures. Stress-induced changes in anisotropic Young's moduli and shear moduli were observed during deformational pathway experiments. A new method was made for the acquisition of compressional and shear wave velocities along a series of 3-dimensional raypaths through a core sample as it is subjected to deformation. Three different deformational pathway experiments were conducted. During the hydrostatic deformation experiment, little or no anisotropy was observed in either the Young's moduli or shear moduli. Significant deformational anisotropies were observed in both moduli during the uniaxial strain test and the triaxial compression experiment but each had a different nature. During the triaxial experiment the axial and lateral Young's moduli and shear moduli continued to diverge as load was applied. During the uniaxial strain experiment the anisotropy was ''locked in'' early in the loading phase but then remained steady as both the confining pressure and axial stress were applied. A new method for measuring anisotropic Biot's effective stress parameters has also been developed. The method involves measuring the compressional and shear wave velocities in the aforementioned acoustic velocity experiments while varying stress paths. For a stress-induced transversely isotropic medium the acoustic velocity data are utilized to calculate the five independent elastic stiffness components. Once the elastic stiffness components are determined these can be used to calculate the anisotropic Biot's effective stress parameters, {alpha}{sub v} and {alpha}{sub h}, using the equations of Abousleiman et al. (1996). A series of experiments have been conducted, on an initially inherently isotropic Berea sandstone rock sample, to dynamically determine these anisotropic Biot's parameters during deformational pathway experiments. Data acquired during hydrostatic, triaxial, and uniaxial strain pathway experiments indicates that Biot's effective stress parameter changes significantly if the applied stresses are not hydrostatic. Variations, as large as 20% between the axial (vertical) and lateral (horizontal) Biot's effective stress parameters, were observed in some experiments. A series of triaxial compression experiments have been conducted on unconsolidated sand (Oil Creek sand) to determine the pressure/stress conditions which would be favorable for liquefaction. Liquefaction of geopressured sands is thought to be one of the major causative mechanisms of damaging shallow water flows. The experiments were developed to determine if: (1) liquefaction could be made to occur in this particular sand at high confining pressures, and (2) the state of liquefication had the same nature at high pressure conditions typical of shallow water flows as it does in low confining pressure soil mechanics tests. A series of undrained triaxial experiments were successfully used to document that the Oil Creek sand could undergo liquefaction. The nature (i.e., the shape of the deformational pathway in mean pressure/shear stress space) was very similar to those observed in soil mechanics experiments. The undrained triaxial experiments also indicated that this sand would strain soften at relatively high confining pressures--a necessary precursor to liquefaction. These experiments serve as a starting point for a series of acoustic experiments to determine the signature of compressional and shear wave properties as the sand packs approach the state of liquefaction (and shallow water flows).

Thurman E. Scott, Jr., Ph.D.; Younane Abousleiman, Ph.D.; Musharraf Zaman, Ph.D., P.E.

2002-04-30

169

Dissipative and hysteresis loops as images of irreversible processes in nonlinear acoustic fields  

NASA Astrophysics Data System (ADS)

Irreversible processes taking place during nonlinear acoustic wave propagation are considered using a representation by loops in a thermodynamic parameter space. For viscous and heat conducting media, the loops are constructed for quasi-harmonic and sawtooth waves and the descriptive equations are formulated. The linear and nonlinear absorptions are compared. For relaxing media, the processes are frequency-dependent. The loops broadens, narrows, and bends. The linear and nonlinear relaxation losses of wave energy are shown. Residual stresses and irreversible strains appear for hysteretic media, and here, a generalization of Rayleigh loops is pictured which takes into account the nonlinearly frequency-dependent hereditary properties. These describe the dynamic behavior, for which new equations are derived.

Hedberg, C. M.; Rudenko, O. V.

2011-09-01

170

Characterization of a Broadband All-Optical Ultrasound Transducer--From Optical and Acoustical Properties to Imaging  

PubMed Central

A broadband all-optical ultrasound transducer has been designed, fabricated, and evaluated for high-frequency ultrasound imaging. The device consists of a 2-D gold nanostructure imprinted on top of a glass substrate, followed by a 3 ?m PDMS layer and a 30 nm gold layer. A laser pulse at the resonance wavelength of the gold nanostructure is focused onto the surface for ultrasound generation, while the gold nanostructure, together with the 30 nm thick gold layer and the PDMS layer in between, forms an etalon for ultrasound detection, which uses a CW laser at a wavelength far from resonance as the probing beam. The center frequency of a pulse-echo signal recorded in the far field of the transducer is 40 MHz with -6 dB bandwidth of 57 MHz. The signal to noise ratio (SNR) from a 70 ?m diameter transmit element combined with a 20 ?m diameter receive element probing a near perfect reflector positioned 1.5 mm from the transducer surface is more than 10 dB and has the potential to be improved by at least another 40 dB. A high-frequency ultrasound array has been emulated using multiple measurements from the transducer while mechanically scanning an imaging target. Characterization of the device’s optical and acoustical properties, as well as preliminary imaging results, strongly suggest that all-optical ultrasound transducers can be used to build high-frequency arrays for real-time high-resolution ultrasound imaging. PMID:18986929

Hou, Yang; Kim, Jin-Sung; Huang, Sheng-Wen; Ashkenazi, Shai; Guo, L. Jay; O'Donnell, Matthew

2009-01-01

171

Do marine substrates 'look' and 'sound' the same? Supervised classification of multibeam acoustic data using autonomous underwater vehicle images  

NASA Astrophysics Data System (ADS)

In this study we outline the techniques used to transform multibeam acoustic data into spatial layers that can be used for predictive habitat modelling. The results allow us to identify multibeam attributes which may act as potential surrogates for environmental variables that influence biodiversity and define which variables may be reliable for predicting the distribution of species in temperate waters. We explore a method for analysing the spatially coincident multibeam bathymetric and backscatter data from shallow coastal waters to generate spatial data products that relate to the classes derived from fine-scale visual imagery obtained using an autonomous underwater vehicle (AUV). Classifications of the multibeam data are performed for substrate, rugosity and sponge cover. Overall classification accuracies for the classes associated with substratum, rugosity and sponge structure were acceptable for biodiversity assessment applications. Accuracies were highest for rugosity classes at 65%, followed by substratum classes at 64% and then sponge structure classes at 57%. Random forest classifiers at a segmentation scale of 30 performed best in classifying substratum and rugosity, while K-nearest neighbour classifiers performed best for sponge structure classes, with no difference in accuracy between scale 30 and 60. Incorporating backscatter variables using segmentation improved the overall accuracy achieved by the best performing model by between 1% (rugosity) and 9% (substratum) above using topographic variables only in the grid-based analyses. Results suggest that image-based backscatter classification show considerable promise for the interpretation of multibeam sonar data for the production of substrate maps. A particular outcome of this research is to provide appropriate and sufficiently fine-scale physical covariates from the multibeam acoustic data to adequately inform models predicting the distribution of biodiversity on benthic reef habitats.

Lucieer, Vanessa; Hill, Nicole A.; Barrett, Neville S.; Nichol, Scott

2013-01-01

172

Acoustic Coupling Gel for Combined Mammography and Ultrasound Image Acquisition and Methods Thereof.  

National Technical Information Service (NTIS)

In accordance with embodiments of the present technique, a combined mammography and ultrasound imaging system is provided. The system includes an ultrasound probe, which transmits ultrasound signals to a breast of a patient and receives reflected ultrasou...

A. Kapur, E. E. Thomenius

2005-01-01

173

Apparatus for real-time acoustic imaging of Rayleigh-Bénard convection  

Microsoft Academic Search

We have successfully designed, built and tested an experimental apparatus which is capable of providing the first real-time ultrasound images of Rayleigh-B\\\\'{e}nard convection in optically opaque fluids confined to large aspect ratio experimental cells. The apparatus employs a modified version of a commercially available ultrasound camera to capture images (30 frames per second) of flow patterns in a fluid undergoing

Kuehn; Kerry

2008-01-01

174

Electronic excitation to singlet states of 1,3-C4F6, c-C4F6 and 2-C4F6 by electron impact--electron energy-loss spectroscopy and ab initio calculations.  

PubMed

We report on the first measurements of the electron impact electronic excitation cross sections for C(4)F(6) isomers, hexafluoro-1,3-butadiene (1,3-C(4)F(6)), hexafluorocyclobutene (c-C(4)F(6)), and hexafluoro-2-butyne (2-C(4)F(6)), measured at 100 eV, 3° scattering angle, while sweeping the energy loss over the range 2.0-15.0 eV. Under these experimental conditions, optically allowed transitions are favored. The electronic state spectroscopy has been investigated and the assignments supported by quantum chemical calculations. The n = 3 members of the Rydberg series have been assigned converging to the lowest ionization energy limits of the C(4)F(6) isomers and classified according to the magnitude of the quantum defects (?). PMID:23074974

Limão-Vieira, P; Anzai, K; Kato, H; Hoshino, M; Ferreira da Silva, F; Duflot, D; Mogi, D; Tanioka, T; Tanaka, H

2012-11-01

175

Particle image velocimetry for the measurement of mean and acoustic particle velocities  

NASA Astrophysics Data System (ADS)

A novel method is outlined which allows measurement of the amplitude of oscillation of a sinusoidal sound field and the mean flow using particle image velocimetry. The method involves simplifying the interrogation area in such a way that the autocorrelation function contains four significant peaks. The accuracy is of the order of half pixel resolution, once a constant offset related to the non-continuous nature of the probability function of a sine wave is taken into account. This constant, which originates from the pixelation of the image, is shown to be 0.85 pixels.

Hann, D. B.; Greated, C. A.

1997-06-01

176

Impact of Acoustic Radiation Force Impulse Imaging in Clinical Practice of Patients after Orthotopic Liver Transplantation  

PubMed Central

Background Acoustic radiation force impulse (ARFI) elastography is a reliable diagnostic device for quantitative non-invasive assessment of liver fibrosis in patients with chronic liver disease. The aim of our prospective study was to evaluate the impact of ARFI in patients after orthotopic liver transplantation (OLT). Therefore, we compared ARFI shear wave velocities with clinical features, non-invasive markers, and the histology of patients following OLT. Material/Methods Post-transplant patients underwent a clinical examination and blood samples were taken. B-mode and Doppler ultrasound (US) of the portal vein and the hepatic artery were performed. Subsequently, a minimum of 10 valid ARFI values were measured in the left and right liver lobe. Liver biopsy was performed if indicated. Results Between May 2012 and May 2014, 58 Patients after OLT were included in the prospective study. Laboratory markers and aspartate aminotransferase-to-platelet ratio index (APRI) correlated with ARFI values (r=0.44, p<0.001). The histological (n=22) fibrosis score (Ludwig) was significantly correlated with the ARFI of the biopsy site (r=0.55, p=0.008). The mean shear-wave velocities were significantly increased in advanced fibrosis (F?2 1.57±0.57 m/s; F?3 2.85±0.66 m/s; p<0.001), obstructive cholestasis and active viral hepatitis. The area under the receiver operating characteristic (AUROC) curves for the accuracy of ARFI were 74% (F?1), 73% (F?2), 93% (F?3), and 80% (=F4). Conclusions ARFI elastography correlates well with laboratory values and with noninvasive and invasive markers of fibrosis in patients after OLT. In this regard, elevated ARFI-velocities should be interpreted with caution in the context of obstructive cholestasis and active viral disease. PMID:25342166

Wildner, Dane; Strobel, Deike; Konturek, Peter C.; Gortz, Rudiger S.; Croner, Roland S.; Neurath, Markus F.; Zopf, Steffen

2014-01-01

177

Photo-acoustic imaging of blue nanoparticle targeted brain tumor for intra-operative glioma delineation  

NASA Astrophysics Data System (ADS)

Distinguishing the tumor from the background neo-plastic tissue is challenging for cancer surgery such as surgical resection of glioma. Attempts have been made to use visible or fluorescent markers to delineate the tumors during surgery. However, the systemic injection of the dyes requires high dose, resulting in negative side effects. A novel method to delineate rat brain tumors intra-operatively, as well as post-operatively, using a highly sensitive photoacoustic imaging technique enhanced by tumor targeting blue nanoparticle as contrast agent is demonstrated. The nanoparticles are made of polyacrylamide (PAA) matrix with covalently linked Coomassie-Blue dye. They contain 7.0% dye and the average size is 80nm. Their surface was conjugated with F3 peptide for active tumor targeting. These nanoparticles are nontoxic, chemically inert and have long plasma circulation lifetime, making them suitable as nanodevices for imaging using photoacoustics. Experiments on phantoms and rat brains tumors ex-vivo demonstrate the high sensitivity of photoacoustic imaging in delineating the tumor, containing contrast agent at concentrations too low to be visualized by eye. The control tumors without nanoparticles did not show any enhanced signal. This study shows that photoacoustic imaging facilitated with the nanoparticle contrast agent could contribute to future surgical procedures for glioma.

Ray, Aniruddha; Wang, Xueding; Koo Lee, Yong-Eun; Hah, HoeJin; Kim, Gwangseong; Chen, Thomas; Orrienger, Daniel; Sagher, Oren; Kopelman, Raoul

2011-07-01

178

70 FR 20618 - Final Nationwide Programmatic Section 4(f) Evaluation and Determination for Federal-Aid...  

Federal Register 2010, 2011, 2012, 2013

...Federal-Aid Transportation Projects That Have a Net Benefit to a Section 4(f) Property AGENCY...property from a historic site results in a net benefit to the Section 4(f) property...Federal-Aid Transportation Projects That Have a Net Benefit to a Section 4(f)...

2005-04-20

179

67 FR 77551 - Draft Nationwide Section 4(f) Evaluation and Proposed Determination for Federal-Aid...  

Federal Register 2010, 2011, 2012, 2013

...Federal-Aid Transportation Projects That Have a Net Benefit to a Section 4(f) Property AGENCIES...or historic property will result in a net benefit to the Section 4(f) property...proposed transportation project result in a net benefit to a Section 4(f)...

2002-12-18

180

Cytochrome P450-Dependent Catabolism of Vitamin K: ?-Hydroxylation Catalyzed by Human CYP4F2 and CYP4F11  

PubMed Central

Vitamin K plays an essential role in many biological processes including blood clotting, maintenance of bone health, and inhibition of arterial calcification. A menaquinone form of vitamin K, MK4, is increasingly recognized for its key roles in mitochondrial electron transport, as a ligand for the nuclear receptor SXR, which controls expression of genes involved in transport and metabolism of endo- and xenobiotics, and as a pharmacotherapeutic in the treatment of osteoporosis. Although cytochrome P450 (CYP) 4F2 activity is recognized as an important determinant of phylloquinone (K1) metabolism, the enzymes involved in menaquinone catabolism have not been studied previously. CYP4F2 and CYP4F11 were expressed and purified and found to be equally efficient as in vitro catalysts of MK4 ?-hydroxylation. CYP4F2, but not CYP4F11, catalyzed sequential metabolism of MK4 to the ?-acid without apparent release of the intermediate aldehyde. The ?-alcohol could also be metabolized to the acid by microsomal NAD+-dependent alcohol and aldehyde dehydrogenases. LC-MS/MS analysis of trypsinized human liver microsomes (using surrogate peptide approach) revealed mean concentrations of CYP4F2 and CYP4F11 to be 14.3 and 8.4 pmol/mg protein, respectively. Microsomal MK4 ?-hydroxylation activities correlated with the CYP4F2 V433M genotype but not CYP4F11 D446N genotype. Collectively, these data expand the lexicon of vitamin K ?-hydroxylases to include the ‘orphan’ P450 CYP4F11 and identify a common variant, CYP4F2 (rs2108622), as a major pharmacogenetic variable influencing MK4 catabolism. PMID:24138531

Edson, Katheryne Z.; Prasad, Bhagwat; Unadkat, Jashvant D.; Suhara, Yoshitomo; Okano, Toshio; Guengerich, F. Peter

2013-01-01

181

Multi-parameter acoustic imaging of uniform objects in inhomogeneous media  

E-print Network

The problem studied in this paper is ultrasound image reconstruction from frequency-domain measurements of the scattered field from an object with contrast in attenuation and sound speed. The case where the object has uniform but unknown contrast in these properties relative to the background is considered. Background clutter is taken into account in a physically realistic manner by considering an exact scattering model for randomly located small scatterers that vary in sound speed. The resulting statistical characteristics of the interference is incorporated into the imaging solution, which includes applying a total-variation minimization based approach where the relative effect of perturbation in sound speed to attenuation is included as a parameter. Convex optimization methods provide the basis for the reconstruction algorithm. Numerical data for inversion examples are generated by solving the discretized Lippman-Schwinger equation for the object and speckle-forming scatterers in the background. A statisti...

Guven, H Emre; Cleveland, Robin O

2011-01-01

182

Acoustic Radiation Force Impulse Imaging for Noninvasive Evaluation of Renal Parenchyma Elasticity: Preliminary Findings  

PubMed Central

Objective To evaluate the diagnostic value of acoustic radiation force impulse (ARFI) to test the elasticity of renal parenchyma by measuring the shear wave velocity (SWV) which might be used to detect chronic kidney disease (CKD). Methods 327 healthy volunteers and 64 CKD patients were enrolled in the study. The potential influencing factors and measurement reproducibility were evaluated in the healthy volunteers. Correlations between SWV and laboratory tests were analyzed in CKD patients.?Receiver-operating characteristic curve (ROC) analyses were performed to assess the diagnostic performance of ARFI. Results The SWV of healthy volunteers correlated significantly to age (r?=??0.22, P<0.001, n?=?327) and differed significantly between men and women (2.06±0.48 m/s vs. 2.2±0.52 m/s, P?=?0.018, n?=?327). However, it did not correlate significantly to height, weight, body mass index, waistline, kidney dimension and the depth for SWV measurement (n?=?30). Inter- and intraobserver agreement expressed as intraclass coefficient correlation were 0.64 (95% CI: 0.13 to 0.82, P?=?0.011) and 0.6 (95% CI: 0.31 to 0.81, P?=?0.001) (n?=?40). The mean SWV in healthy volunteers was 2.15±0.51 m/s, while was 1.81±0.43 m/s, 1.79±0.29 m/s, 1.81±0.44 m/s, 1.64±0.55 m/s, and 1.36±0.17 m/s for stage 1, 2, 3, 4 and 5 in CKD patients respectively. The SWV was significantly higher for healthy volunteers compared with each stage in CKD patients. ARFI could not predict the different stages of CKD except stage 5. In CKD patients, SWV correlated to e-GFR (r?=?0.3, P?=?0.018), to urea nitrogen (r?=? ?0.3, P?=?0.016), and to creatinine (r?=? ?0.41, P?=?0.001). ROC analyses indicated that the area under the ROC curve was 0.752 (95% CI: 0.704 to 0.797) (P<0.001). The cut-off value for predicting CKD was 1.88 m/s (sensitivity 71.87% and specificity 69.69%). Conclusion ARFI may be a potentially useful tool in detecting CKD. PMID:23874814

Xu, Hui-Xiong; Peng, Ai; Zhang, Yi-Feng; Liu, Lin-Na

2013-01-01

183

Signal/Image Processing of Acoustic Flaw Signatures for Detection and Localization  

SciTech Connect

The timely, nondestructive evaluation (NDE) of critical optics in high energy, pulsed laser experiments is a crucial analysis that must be performed for the experiment to be successful. Failure to detect flaws of critical sizes in vacuum-loaded optical windows can result in a catastrophic failure jeopardizing the safety of both personnel and costly equipment. We discuss the development of signal/image processing techniques to both detect critical flaws and locate their position on the window. The data measured from two Orthogonal arrays of narrow beamwidth ultrasonic transducers are preprocessed using a model-based scheme based on the Green's function of the medium providing individual channel signatures. These signatures are then transformed to the two-dimensional image space using a power-based estimator. A 2D-replicant is then constructed based on the underlying physics of the material along with the geometry of the window. Correlating the replicant with the enhanced power image leads to the optimal 2D-matched filter solution detecting and localizing the flaw. Controlled experimental results on machined flaws are discussed.

Candy, J V; Meyer, A W

2001-06-01

184

http://www.sjsu.edu/senate/f79-4.htm F79-4, F83-4, F87-7 ATHLETICS BOARD  

E-print Network

be made in a balanced fashion that insures quality and integrity in all affairs. Athletes, as a parthttp://www.sjsu.edu/senate/f79-4.htm F79-4, F83-4, F87-7 ATHLETICS BOARD Legislative History the following policy recommendation to, as presented by Dr. Lucius Eastman for the Athletics Board

Gleixner, Stacy

185

Properties of C4F8 inductively coupled plasmas. I. Studies of Arc-C4F8 magnetically confined plasmas for etching of SiO2  

E-print Network

Properties of C4F8 inductively coupled plasmas. I. Studies of Ar�c-C4F8 magnetically confined parameters of systems using these mixtures, inductively coupled plasmas in the pressure range of 6­20 m and inductively coupled plasmas ICPs are used for etching, very often us- ing static magnetic fields to optimize

Kushner, Mark

186

Acoustic performance of mesh compression paddles for a multimodality breast imaging system.  

PubMed

A system incorporating automated 3-D ultrasound and digital X-ray tomosynthesis is being developed for improved breast lesion detection and characterization. The goal of this work is to develop and test candidates for a dual-modality mesh compression paddle. A Computerized Imaging Reference Systems (Norfork, VA, USA) ultrasound phantom with tilted low-contrast cylindrical objects was used. Polyester mesh fabrics (1- and 2-mm spacing), a high-density polyethylene filament grid (Dyneema, DSM Dyneema, Stanley, NC, USA) and a solid polymethylpentene (TPX; Mitsui Plastics, Inc., White Plains, NY) paddle were compared with no overlying structures using a GE Logic 9 with M12L transducer. A viscous gel provided coupling. The phantom was scanned 10 times over 9 cm for each configuration. Image volumes were analyzed for signal strength, contrast and contrast-to-noise ratio. X-ray tests confirmed X-ray transparency for all materials. By all measures, both mesh fabrics outperformed TPX and Dyneema, and there were essentially no differences between 2-mm mesh and unobstructed configurations. PMID:24726203

LeCarpentier, Gerald L; Goodsitt, Mitchell M; Verweij, Sacha; Li, Jie; Padilla, Frederic R; Carson, Paul L

2014-07-01

187

Multi-parameter acoustic imaging of uniform objects in inhomogeneous soft tissue.  

PubMed

The problem studied in this paper is ultrasound image reconstruction from frequency-domain measurements of the scattered field from an object with contrast in attenuation and sound speed. The case in which the object has uniform but unknown contrast in these properties relative to the background is considered. Background clutter is taken into account in a physically realistic manner by considering an exact scattering model for randomly located small scatterers that vary in sound speed. The resulting statistical characteristics of the interference are incorporated into the imaging solution, which includes application of a total-variation minimization-based approach in which the relative effect of perturbation in sound speed to attenuation is included as a parameter. Convex optimization methods provide the basis for the reconstruction algorithm. Numerical data for inversion examples are generated by solving the discretized Lippman-Schwinger equation for the object and speckle-forming scatterers in the background. A statistical model based on the Born approximation is used for reconstruction of the object profile. Results are presented for a two-dimensional problem in terms of classification performance and compared with minimum-l2-norm reconstruction. Classification using the proposed method is shown to be robust down to a signal-to-clutter ratio of less than 1 dB. PMID:22899117

Güven, H Emre; Miller, Eric L; Cleveland, Robin O

2012-08-01

188

Institute of Fluid Mechanics and Engineering Acoustics  

E-print Network

Institute of Fluid Mechanics and Engineering Acoustics Sound Transmission Lab Click to insert the image of the facility or test-rig Application area Facility Mechanical Property measurement Physical Property measurement Acoustical Property measurement Parameter Principle/Method: Standard

Berlin,Technische Universität

189

VHMPID RICH prototype using pressurized C4F8O radiator gas and VUV photon detector  

NASA Astrophysics Data System (ADS)

A small-size prototype of a new Ring Imaging Cherenkov (RICH) detector using for the first time pressurized C4F8O radiator gas and a photon detector consisting of MWPC equipped with a CsI photocathode has been built and tested at the PS accelerator at CERN. It contained all the functional elements of the detector proposed as Very High Momentum Particle Identification (VHMPID) upgrade for the ALICE experiment at LHC to provide charged hadron track-by-track identification in the momentum range starting from 5 potentially up to 25 GeV/c. In the paper the equipment and its elements are described and some characteristic test results are shown.

Acconcia, T. V.; Agócs, A. G.; Barile, F.; Barnaföldi, G. G.; Bellwied, R.; Bencédi, G.; Bencze, G.; Berényi, D.; Boldizsár, L.; Chattopadhyay, S.; Chinellato, D. D.; Cindolo, F.; Cossyleon, K.; Das, D.; Das, K.; Das-Bose, L.; Dash, A. K.; D'Ambrosio, S.; De Cataldo, G.; De Pasquale, S.; Di Bari, D.; Di Mauro, A.; Futó, E.; Garcia-Solis, E.; Hamar, G.; Harton, A.; Iannone, G.; Jimenez, R. T.; Kim, D. W.; Kim, J. S.; Knospe, A.; Kovács, L.; Lévai, P.; Markert, C.; Martinengo, P.; Molnár, L.; Nappi, E.; Oláh, L.; Pai?, G.; Pastore, C.; Patimo, G.; Patino, M. E.; Peskov, V.; Pinsky, L.; Piuz, F.; Pochybová, S.; Sgura, I.; Sinha, T.; Song, J.; Takahashi, J.; Timmins, A.; Van Beelen, J. B.; Varga, D.; Volpe, G.; Weber, M.; Xaplanteris, L.; Yi, J.; Yoo, I.-K.

2014-12-01

190

Feasibility of High Frequency Acoustic Imaging for Inspection of Containments: Phase II  

SciTech Connect

The nuclear power industry is concerned with corrosive thinning of portions of the metallic pressure boundary, particularly in areas that are not directly accessible for inspection. This study investigated the feasibility of detecting these thickness degradations using ultrasonic imaging. A commercial ultrasonic system was used to carry out several full-scale, controlled laboratory experiments. Measurements of 0.5 MHz shear wave levels propagated in 25-mm-thick steel plate embedded in concrete showed 1.4-1.6 dB of signal loss for each centimeter of two-way travel in the steel plate (compared to previous numerical predictions of 3-4 dB), and 1.3 dB of signal loss per centimeter of two-way travel in steel plates embedded in concrete prior to setting of the concrete (i.e., plastic). Negligible losses were measured in plates with a decoupling treatment applied between the steel and concrete to simulate the unbonded portions of the pressure boundary. Scattered signals from straight slots of different size and shape were investigated. The return from a 4-mm-deep rectangular slots exhibited levels 23 dB down relative to incidence and 4-6 dB higher than those obtained from both ''v'' shaped and rounded slots of similar depth. The system displayed an input/output dynamic range of 125 dB and measurement variability less than 1-2dB. Based on these results, a 4-mm-deep, rounded degradation embedded 30 cm in concrete has expected returns of -73dB relative to the input and should therefore be detectable. Results of this and a prior study indicate that the technique has merit and should be developed more fully and demonstrated in the field.

Rudzinsky, J.; Bondaryk, J.; Conti, M.

1999-07-01

191

Comparison of deconvolution methods for the visualization of acoustic sources based on cross-spectral imaging function beamforming  

NASA Astrophysics Data System (ADS)

DAMAS, DAMAS2, NNLS, Fourier-based NNLS, CLEAN and CLEAN-SC are typical deconvolution methods, which have been used in the visualization of acoustic sources based on beamforming to improve the spatial resolution and the dynamic range effectively. It is of great significance to demonstrate and compare properties of these methods comprehensively. In this paper, these methods are applied to cross-spectral imaging function (CSIF) beamforming with auto-spectra exclusion and their properties are demonstrated and compared with each other first by computational simulations consisting of a single source, two incoherent sources and two coherent sources. All the deconvolution methods can visualize single source or incoherent sources in the region where the assumption of shift invariant point spread function is valid accurately and clearly. Not only the spatial resolution is improved dramatically, but also the sidelobes are eliminated effectively. In addition, these methods rank in a diminishing sequence of sidelobe elimination ability from CLEAN-SC, CLEAN, DAMAS, Fourier-based NNLS, NNLS to DAMAS2. When the sources are out of the valid region, only DAMAS, NNLS, CLEAN and CLEAN-SC succeed in visualizing the sources and CLEAN-SC and CLEAN acquire the cleanest source images, then DAMAS, finally NNLS, while DAMAS2 and Fourier-based NNLS fail to not only locate the sources but also capture the strengths. DAMAS, DAMAS2, NNLS and Fourier-based NNLS have good availability for coherent sources in the valid region. In contrast, CLEAN fails to remove sidelobes effectively and CLEAN-SC can only detect one source. DAMAS2 and Fourier-based NNLS also perform poorly for coherent sources out of the valid region. Additionally, DAMAS2 and Fourier-based NNLS consume a minimum of time to conduct a calculation, CLEAN and CLEAN-SC take the second place, whereas DAMAS and NNLS are the slowest. Then a series of experiments are performed on small loudspeakers to validate simulations and compare robustness of these deconvolution methods in practical applications. Some practical factors such as the frequency response characteristic mismatch among the measurement devices have almost no influence on the results of CLEAN-SC, bring some change to the results of DAMAS, DAMAS2, NNLS and Fourier-based NNLS in terms of reconstructed maximum values, sidelobes, etc., and contribute plenty of extra sidelobe contaminations to the results of CLEAN. The conclusions play a guiding significance on the application of these deconvolution methods in practical engineering.

Chu, Zhigang; Yang, Yang

2014-10-01

192

Acoustic Source Localization Using the Acoustic ENSBox  

E-print Network

Acoustic Source Localization Using the Acoustic ENSBox Andreas M. Ali Kung Yao Electrical of new deployable acoustic sensor platforms presents opportunities to develop automated tools for bio-acoustic Keywords Bioacoustics, distributed signal processing, acoustic source localization, wireless sensor

Grether, Gregory

193

Acoustic Neuroma  

MedlinePLUS

An acoustic neuroma is a benign tumor that develops on the nerve that connects the ear to the brain. ... can press against the brain, becoming life-threatening. Acoustic neuroma can be difficult to diagnose, because the ...

194

Evaluating the feasibility of acoustic radiation force impulse shear wave elasticity imaging of the uterine cervix with an intracavity array: a simulation study.  

PubMed

The uterine cervix softens, shortens, and dilates throughout pregnancy in response to progressive disorganization of its layered collagen microstructure. This process is an essential part of normal pregnancy, but premature changes are associated with preterm birth. Clinically, there are no reliable noninvasive methods to objectively measure cervical softening or assess cervical microstructure. The goal of these preliminary studies was to evaluate the feasibility of using an intracavity ultrasound array to generate acoustic radiation force impulse (ARFI) excitations in the uterine cervix through simulation, and to optimize the acoustic radiation force (ARF) excitation for shear wave elasticity imaging (SWEI) of the tissue stiffness. The cervix is a unique soft tissue target for SWEI because it has significantly greater acoustic attenuation (? = 1.3 to 2.0 dB·cm(-1)·MHz(-)1) than other soft tissues, and the pathology being studied tends to lead to an increase in tissue compliance, with healthy cervix being relatively stiff compared with other soft tissues (E ? 25 kPa). Additionally, the cervix can only be accessed in vivo using a transvaginal or catheter-based array, which places additional constraints on the excitation focal characteristics that can be used during SWEI. Finite element method (FEM) models of SWEI show that larger-aperture, catheter-based arrays can utilize excitation frequencies up to 7 MHz to generate adequate focal gain up to focal depths 10 to 15 mm deep, with higher frequencies suffering from excessive amounts of near-field acoustic attenuation. Using full-aperture excitations can yield ~40% increases in ARFI-induced displacements, but also restricts the depth of field of the excitation to ~0.5 mm, compared with 2 to 6 mm, which limits the range that can be used for shear wave characterization of the tissue. The center-frequency content of the shear wave particle velocity profiles ranges from 1.5 to 2.5 kHz, depending on the focal configuration and the stiffness of the material being imaged. Overall, SWEI is possible using catheter-based imaging arrays to generate adequate displacements in cervical tissue for shear wave imaging, although specific considerations must be made when optimizing these arrays for this shear wave imaging application. PMID:24081254

Palmeri, Mark L; Feltovich, Helen; Homyk, Andrew D; Carlson, Lindsey C; Hall, Timothy J

2013-10-01

195

Acoustic Seal  

NASA Technical Reports Server (NTRS)

The invention relates to a sealing device having an acoustic resonator. The acoustic resonator is adapted to create acoustic waveforms to generate a sealing pressure barrier blocking fluid flow from a high pressure area to a lower pressure area. The sealing device permits noncontacting sealing operation. The sealing device may include a resonant-macrosonic-synthesis (RMS) resonator.

Steinetz, Bruce M. (Inventor)

2006-01-01

196

Acoustic seal  

NASA Technical Reports Server (NTRS)

The invention relates to a sealing device having an acoustic resonator. The acoustic resonator is adapted to create acoustic waveforms to generate a sealing pressure barrier blocking fluid flow from a high pressure area to a lower pressure area. The sealing device permits noncontacting sealing operation. The sealing device may include a resonant-macrosonic-synthesis (RMS) resonator.

Steinetz, Bruce M. (Inventor)

2006-01-01

197

The screening of 4f moments and delocalization in the compressed light rare earths  

SciTech Connect

Spin and charge susceptibilities and the 4f{sup n}, 4f{sup n{+-}1} configuration weights are calculated for compressed Ce (n=1), Pr (n=2), and Nd (n=3) metals using dynamical mean field theory combined with the local-density approximation. At ambient and larger volumes these trivalent rare earths are pinned at sharp 4f{sup n} configurations, their 4f moments assume atomic-limiting values, are unscreened, and the 4f charge fluctuations are small indicating little f state density near the Fermi level. Under compresssion there is dramatic screening of the moments and an associated increase in both the 4f charge fluctuations and static charge susceptibility. These changes are coincident with growing weights of the 4f{sup n-1} configurations, which it is argued are better measures of delocalization than the 4f{sup n+1} weights which are compromised by an increase in the number of 4f electrons caused by rising 6s, 6p bands. This process is continuous and prolonged as a function of volume, with strikingly similarity among the three rare earths, aside from the effects moderating and shifting to smaller volumes for the heavier members. The observed {alpha}-{gamma} collapse in Ce occurs over the large-volume half of this evolution, the Pr analog at smaller volumes, and Nd has no collapse.

McMahan, A K; Scalettar, R T; Jarrell, M

2009-08-19

198

Acoustic emission linear pulse holography  

DOEpatents

This device relates to the concept of and means for performing Acoustic Emission Linear Pulse Holography, which combines the advantages of linear holographic imaging and Acoustic Emission into a single non-destructive inspection system. This unique system produces a chronological, linear holographic image of a flaw by utilizing the acoustic energy emitted during crack growth. The innovation is the concept of utilizing the crack-generated acoustic emission energy to generate a chronological series of images of a growing crack by applying linear, pulse holographic processing to the acoustic emission data. The process is implemented by placing on a structure an array of piezoelectric sensors (typically 16 or 32 of them) near the defect location. A reference sensor is placed between the defect and the array.

Collins, H.D.; Busse, L.J.; Lemon, D.K.

1983-10-25

199

Acoustic characterization of contrast-to-tissue ratio and axial resolution for dual-frequency contrast-specific acoustic angiography imaging.  

PubMed

Recently, dual-frequency transducers have enabled high-spatial-resolution and high-contrast imaging of vasculature with minimal tissue artifacts by transmitting at a low frequency and receiving broadband superharmonic echoes scattered by microbubble contrast agents. In this work, we examine the imaging parameters for optimizing contrast-totissue ratio (CTR) for dual-frequency imaging and the relationship with spatial resolution. Confocal piston transducers are used in a water bath setup to measure the SNR, CTR, and axial resolution for ultrasound imaging of nonlinear scattering of microbubble contrast agents when transmitting at a lower frequency (1.5 to 8 MHz) and receiving at a higher frequency (7.5 to 25 MHz). Parameters varied include the frequency and peak negative pressure of transmitted waves, center frequency of the receiving transducer, microbubble concentration, and microbubble size. CTR is maximized at the lowest transmission frequencies but would be acceptable for imaging in the 1.5 to 3.5 MHz range. At these frequencies, CTR is optimized when a receiving transducer with a center frequency of 10 MHz is used, with the maximum CTR of 25.5 dB occurring when transmitting at 1.5 MHz with a peak negative pressure of 1600 kPa and receiving with a center frequency of 10 MHz. Axial resolution is influenced more heavily by the receiving center frequency, with a weak decrease in measured pulse lengths associated with increasing transmit frequency. A microbubble population containing predominately 4-?m-diameter bubbles yielded the greatest CTR, followed by 1- and then 2-?m bubbles. Varying concentration showed little effect over the tested parameters. CTR dependence on transmit frequency and peak pressure were confirmed through in vivo imaging in two rodents. These findings may lead to improved imaging of vascular remodeling in superficial or luminal cancers such as those of the breast, prostate, and colon. PMID:25265176

Lindsey, Brooks; Rojas, Juan; Martin, K; Shelton, Sarah; Dayton, Paul

2014-10-01

200

The first intron of the 4F2 heavy-chain gene contains a transcriptional enhancer element that binds multiple nuclear proteins.  

PubMed Central

We utilized the human 4F2 heavy-chain (4F2HC) gene as a model system to study the regulation of inducible gene expression during normal human T-cell activation. Previous studies have demonstrated that 4F2HC gene expression is induced during normal T-cell activation and that the activity of the gene is regulated, at least in part, by the interaction of a constitutively active 5'-flanking housekeeping promoter and a phorbol ester-responsive transcriptional attenuator element located in the exon 1-intron 1 region of the gene. We now report that 4F2HC intron 1 contains a transcriptional enhancer element which is active on a number of heterologous promoters in a variety of murine and human cells. This enhancer element has been mapped to a 187-base-pair RsaI-AluI fragment from 4F2HC intron 1. DNase I footprinting and gel mobility shift analyses demonstrated that this fragment contains two nuclear protein-binding sites (NF-4FA and NF-4FB) which flank a consensus binding site for the inducible AP-1 transcription factor. Deletion analysis showed that the NF-4FA, NF-4FB, and AP-1 sequences are each necessary for full enhancer activity. Murine 4F2HC intron 1 displayed enhancer activity similar to that of its human counterpart. Comparison of the sequences of human and murine 4F2HC intron 1s demonstrated that the NF-4FA, NF-4FB, and AP-1 sequence motifs have been highly conserved during mammalian evolution. Images PMID:2761540

Karpinski, B A; Yang, L H; Cacheris, P; Morle, G D; Leiden, J M

1989-01-01

201

L-4F Inhibits Lipopolysaccharide-Mediated Activation of Primary Human Neutrophils.  

PubMed

Human apolipoprotein A-I (apoA-I) mimetic L-4F inhibits acute inflammation in endotoxemic animals. Since neutrophils play a crucial role in septic inflammation, we examined the effects of L-4F, compared to apoA-I, on lipopolysaccharide (LPS)-mediated activation of human neutrophils. We performed bioassays in human blood, isolated human neutrophils (incubated in 50 % donor plasma), and isolated human leukocytes (incubated in 5 and 50 % plasma) in vitro. In whole blood, both L-4F and apoA-I inhibited LPS-mediated elevation of TNF-? and IL-6. In LPS-stimulated neutrophils, L-4F and apoA-I (40 ?g/ml) also decreased myeloperoxidase and TNF-? levels; however, L-4F tended to be superior in inhibiting LPS-mediated increase in IL-6 levels, membrane lipid rafts abundance and CD11b expression. In parallel experiments, when TNF-? and IL-8, instead of LPS, was used for cell stimulation, L-4F and/or apoA-I revealed only limited efficacy. In LPS-stimulated leukocytes, L-4F was as effective as apoA-I in reducing superoxide formation in 50 % donor plasma, and more effective in 5 % donor plasma (P?4F neutralizes LAL endotoxin activity more effectively than apoA-I (P?4F in vitro; (2) while L-4F has similar efficacy to apoA-I in anti-endotoxin effects in whole blood, it demonstrates superior efficacy to apoA-I in aqueous solutions and fluids with limited plasma components. This study rationalizes the utility of L-4F in the treatment of inflammation that is mediated by endotoxin-activated neutrophils. PMID:24647607

Sharifov, Oleg F; Xu, Xin; Gaggar, Amit; Tabengwa, Edlue M; White, C Roger; Palgunachari, Mayakonda N; Anantharamaiah, G M; Gupta, Himanshu

2014-10-01

202

Virtual Touch Tissue Quantification of Acoustic Radiation Force Impulse: A New Ultrasound Elastic Imaging in the Diagnosis of Thyroid Nodules  

PubMed Central

Objective Virtual touch tissue quantification (VTQ) of acoustic radiation force impulse (ARFI) is a new quantitative technique to measure tissue stiffness. The study was aimed to assess the usefulness of VTQ in the diagnosis of thyroid nodules. Methods 173 pathologically proven thyroid nodules in 142 patients were included and all were examined by conventional ultrasound (US), conventional elasticity imaging (EI) and VTQ of ARFI. The tissue stiffness for VTQ was expressed as shear wave velocity (SWV) (m/s). Receiver-operating characteristic curve (ROC) analyses were performed to assess the diagnostic performance. Intra- and inter-observer reproducibility of VTQ measurement was assessed. Results The SWVs of benign and malignant thyroid nodules were 2.34±1.17 m/s (range: 0.61–9.00 m/s) and 4.82±2.53 m/s (range: 2.32–9.00 m/s) respectively (P<0.001). The mean SWV ratios between each nodule and the adjacent thyroid tissue were 1.19±0.67 (range: 0.31–6.87) for benign and 2.50±1.54 (range: 0.85–6.69) for malignant nodules (P<0.001). ROC analyses indicated that the area under the curve was 0.861 (95% CI : 0.804, 0.918) (P<0.001) for SWV and 0.831(95% CI : 0.761, 0.900)(P<0.001) for the SWV ratio. The cutoff points for the differential diagnosis were 2.87 m/s for SWV and 1.59 for SWV ratio. The sensitivity, specificity, accuracy, positive predictive value, and negative predictive value for EI were 65.9%, 66.7%, 66.5%, 40.3%, and 85.1%, respectively, and were 63.6%–75%, 82.2%–88.4%, 80.3%–82.1%, 58.9%–65.1%, and 87.7%–90.5%, respectively, for VTQ. The diagnostic value of VTQ is the highest for nodules >20 mm and lowest for those ?10 mm. The correlation coefficients were 0.904 for intraobserver measurement and 0.864 for interobserver measurement. Conclusions VTQ of ARFI provides quantitative and reproducible information about the tissue stiffness, which is useful for the differentiation between benign and malignant thyroid nodules. The diagnostic performance of VTQ is higher than that of conventional EI. PMID:23152855

Zhang, Yi-Feng; Xu, Hui-Xiong; He, Yong; Liu, Chang; Guo, Le-Hang; Liu, Lin-Na; Xu, Jun-Mei

2012-01-01

203

Cowpea mosaic virus middle component RNA contains a sequence that allows internal binding of ribosomes and that requires eukaryotic initiation factor 4F for optimal translation.  

PubMed Central

Cowpea mosaic virus (CPMV) middle component RNA (M-RNA) encodes two proteins of 105 and 95 kDa, of which translation starts at nucleotide (nt) 161 and nt 512, respectively. In vitro translation of both proteins directed by T7 transcripts of M-RNA was stimulated fourfold by eukaryotic initiation factor 4F (eIF-4F), the cap-binding protein complex. The ratio of the synthesis of both proteins after translation was not influenced by eIF-4F or by any known eIF. Part of the CPMV 5' sequence was cloned downstream of the 5' untranslated region of ornithine decarboxylase (ODC); the latter untranslated sequence has a highly stable secondary structure, preventing efficient translation of ODC. Insertion of nt 161 to 512 of CPMV M-RNA upstream of the ODC initiation codon resulted in a marked increase in ODC translation, which indicates that the CPMV sequence contains an internal ribosome-binding site. The insertion conferred stimulation by eIF-4F on ODC translation, showing that eIF-4F is able to stimulate internal initiation. Images PMID:2033661

Thomas, A A; ter Haar, E; Wellink, J; Voorma, H O

1991-01-01

204

Autophagy . Author manuscript E4F1 dysfunction results in autophagic cell death in myeloid leukemic  

E-print Network

Autophagy . Author manuscript Page /1 2 E4F1 dysfunction results in autophagic cell death Animals ; Autophagy ; Cell Survival ; Cell Transformation, Neoplastic ; pathology ; Disease Models, Animal sarcoma ; mitochondria ; autophagy ; cell death ; leukemic cells ; reactive oxygen species E4F1 was first

Paris-Sud XI, Université de

205

Acoustic imaging and collimating by slabs of sonic crystals made from arrays of rigid cylinders in air  

Microsoft Academic Search

We show some properties of the acoustic propagation in two-dimensional sonic crystals, formed by parallel rigid cylinders placed in air. The transmission through slabs of sonic crystals and the associated band structures are considered. It is shown that within partial band gaps, the waves tend to be collimated or guided into the direction in which the propagation is allowed. Such

Liang-Shan Chen; Chao-Hsien Kuo; Zhen Ye

2004-01-01

206

Acoustic imaging of harmonic near-field sources from surface pressure measurements on a body using singular value decomposition  

Microsoft Academic Search

An inverse or backward projection method based on a combined Greens function and singular value decomposition method is developed to locate and to determine the strength of near field harmonic sources from the acoustic field on the surface of a nearby rigid body. A resolution matrix, which is based on the free space Greens function, the geometry of the measurement

Peter R. Stepanishen; Irsan Brodjonegoro

2002-01-01

207

Vacuum-ultraviolet interconfigurational 4f3 rightarrow 4f25d absorption and emission studies of the Nd3+ ion in KYF, YF, and YLF crystal hosts  

NASA Astrophysics Data System (ADS)

The laser-induced vacuum-ultraviolet fluorescence spectra of KY3F10:Nd3+ (KYF:Nd) and YF3:Nd3+ (YF:Nd) single crystals pumped by a pulsed-discharge molecular F2 laser at 157 nm were obtained. A number of new fluorescence peaks were observed and were assigned to the 4f25d \\rightarrow 4f 3 dipole-allowed transitions of the Nd 3+ ion. The absorption spectra of LiYF 4:Nd3+ (YLF:Nd), KYF:Nd, and YF:Nd crystal samples in the vacuum-ultraviolet spectral regions were also obtained. Finally, the splitting of the states of the 4f25d configuration of the Nd3+ ion, which is due to the crystal field, was observed in all the crystal samples.

Kollia, Z.; Sarantopoulou, E.; Cefalas, A. C.; Nicolaides, C. A.; Naumov, A. K.; Semashko, V. V.; Abdulsabirov, R. Y.; Korableva, S. L.; Dubinskii, M. A.

1995-05-01

208

Vascular characterization of mice with endothelial expression of cytochrome P450 4F2.  

PubMed

Cytochrome P450 (CYP) 4A and 4F enzymes metabolize arachidonic acid to 20-hydroxyeicosatetraenoic acid (20-HETE). Although CYP4A-derived 20-HETE is known to have prohypertensive and proangiogenic properties, the effects of CYP4F-derived metabolites are not well characterized. To investigate the role of CYP4F2 in vascular disease, we generated mice with endothelial expression of human CYP4F2 (Tie2-CYP4F2-Tr). LC/MS/MS analysis revealed 2-foldincreases in 20-HETE levels in tissues and endothelial cells (ECs), relative to wild-type (WT) controls. Tie2-CYP4F2-Tr ECs demonstrated increases in growth (267.1 ± 33.4 vs. 205.0 ± 13% at 48 h) and tube formation (7.7 ± 1.1 vs. 1.6 ± 0.5 tubes/field) that were 20-HETE dependent and associated with up-regulation of prooxidant NADPH oxidase and proangiogenic VEGF. Increases in VEGF and NADPH oxidase levels were abrogated by inhibitors of NADPH oxidase and MAPK, respectively, suggesting the possibility of crosstalk between pathways. Interestingly, IL-6 levels in Tie2-CYP4F2-Tr mice (18.6 ± 2.7 vs. 7.9 ± 2.7 pg/ml) were up-regulated via NADPH oxidase- and 20-HETE-dependent mechanisms. Although Tie2-CYP4F2-Tr aortas displayed increased vasoconstriction, vasorelaxation and blood pressure were unchanged. Our findings indicate that human CYP4F2 significantly increases 20-HETE production, CYP4F2-derived 20-HETE mediates EC proliferation and angiogenesis via VEGF- and NADPH oxidase-dependent manners, and the Tie2-CYP4F2-Tr mouse is a novel model for examining the pathophysiological effects of CYP4F2-derived 20-HETE in the vasculature.-Cheng, J., Edin, M. L., Hoopes, S. L., Li, H., Bradbury, J. A., Graves, J. P., DeGraff, L. M., Lih, F. B., Garcia, V., Shaik, J. S. B., Tomer, K. B., Flake, G. P., Falck, J. R., Lee, C. R., Poloyac, S. M., Schwartzman, M. L., Zeldin, D. C. Vascular characterization of mice with endothelial expression of cytochrome P450 4F2. PMID:24668751

Cheng, Jennifer; Edin, Matthew L; Hoopes, Samantha L; Li, Hong; Bradbury, J Alyce; Graves, Joan P; DeGraff, Laura M; Lih, Fred B; Garcia, Victor; Shaik, Jafar Sadik B; Tomer, Kenneth B; Flake, Gordon P; Falck, John R; Lee, Craig R; Poloyac, Samuel M; Schwartzman, Michal L; Zeldin, Darryl C

2014-07-01

209

A rail system for circular synthetic aperture sonar imaging and acoustic target strength measurements: Design/operation/preliminary results  

NASA Astrophysics Data System (ADS)

A 22 m diameter circular rail, outfitted with a mobile sonar tower trolley, was designed, fabricated, instrumented with underwater acoustic transducers, and assembled on a 1.5 m thick sand layer at the bottom of a large freshwater pool to carry out sonar design and target scattering response studies. The mobile sonar tower translates along the rail via a drive motor controlled by customized LabVIEW software. The rail system is modular and assembly consists of separately deploying eight circular arc sections, measuring a nominal center radius of 11 m and 8.64 m arc length each, and having divers connect them together in the underwater environment. The system enables full scale measurements on targets of interest with 0.1° angular resolution over a complete 360° aperture, without disrupting target setup, and affording a level of control over target environment conditions and noise sources unachievable in standard field measurements. In recent use, the mobile cart carrying an instrumented sonar tower was translated along the rail in 720 equal position increments and acoustic backscatter data were acquired at each position. In addition, this system can accommodate both broadband monostatic and bistatic scattering measurements on targets of interest, allowing capture of target signature phenomena under diverse configurations to address current scientific and technical issues encountered in mine countermeasure and unexploded ordnance applications. In the work discussed here, the circular rail apparatus is used for acoustic backscatter testing, but this system also has the capacity to facilitate the acquisition of magnetic and optical sensor data from targets of interest. A brief description of the system design and operation will be presented along with preliminary processed results for data acquired from acoustic measurements conducted at the Naval Surface Warfare Center, Panama City Division Test Pond Facility. [Work Supported by the U.S. Office of Naval Research and The Strategic Environmental Research and Development Program.

Kennedy, J. L.; Marston, T. M.; Lee, K.; Lopes, J. L.; Lim, R.

2014-01-01

210

A rail system for circular synthetic aperture sonar imaging and acoustic target strength measurements: design/operation/preliminary results.  

PubMed

A 22 m diameter circular rail, outfitted with a mobile sonar tower trolley, was designed, fabricated, instrumented with underwater acoustic transducers, and assembled on a 1.5 m thick sand layer at the bottom of a large freshwater pool to carry out sonar design and target scattering response studies. The mobile sonar tower translates along the rail via a drive motor controlled by customized LabVIEW software. The rail system is modular and assembly consists of separately deploying eight circular arc sections, measuring a nominal center radius of 11 m and 8.64 m arc length each, and having divers connect them together in the underwater environment. The system enables full scale measurements on targets of interest with 0.1° angular resolution over a complete 360° aperture, without disrupting target setup, and affording a level of control over target environment conditions and noise sources unachievable in standard field measurements. In recent use, the mobile cart carrying an instrumented sonar tower was translated along the rail in 720 equal position increments and acoustic backscatter data were acquired at each position. In addition, this system can accommodate both broadband monostatic and bistatic scattering measurements on targets of interest, allowing capture of target signature phenomena under diverse configurations to address current scientific and technical issues encountered in mine countermeasure and unexploded ordnance applications. In the work discussed here, the circular rail apparatus is used for acoustic backscatter testing, but this system also has the capacity to facilitate the acquisition of magnetic and optical sensor data from targets of interest. A brief description of the system design and operation will be presented along with preliminary processed results for data acquired from acoustic measurements conducted at the Naval Surface Warfare Center, Panama City Division Test Pond Facility. [Work Supported by the U.S. Office of Naval Research and The Strategic Environmental Research and Development Program.]. PMID:24517797

Kennedy, J L; Marston, T M; Lee, K; Lopes, J L; Lim, R

2014-01-01

211

Acoustic hemostasis  

NASA Astrophysics Data System (ADS)

In cases of severe injury, physicians speak of a "golden hour"—a brief grace period in which quickly applied, proper therapy can save the life of the patient. Much of this mortality results from exsanguination, i.e., bleeding to death—often from internal hemorrhage. The inability of a paramedic to treat breaches in the vascular system deep within the body or to stem the loss of blood from internal organs is a major reason for the high level of mortality associated with blunt trauma. We have undertaken an extensive research program to treat the problem of internal bleeding. Our approach is as follows: (a) We use scanning ultrasound to identify internal bleeding and hemorrhage, (b) we use ultrasound imaging to locate specific breaches in the vascular system, both from damaged vessels and gross damage to the capillary bed, and (c) we use High Intensity Focused Ultrasound (HIFU) to treat the damaged region and to induce hemostasis. We present a general review of this research with some emphasis on the role of nonlinear acoustics.

Crum, Lawrence; Beach, Kirk; Carter, Stephen; Chandler, Wayne; Curra, Francesco; Kaczkowski, Peter; Keilman, George; Khokhlova, Vera; Martin, Roy; Mourad, Pierre; Vaezy, Shahram

2000-07-01

212

Musical Acoustics  

NASA Astrophysics Data System (ADS)

This chapter provides an introduction to the physical and psycho-acoustic principles underlying the production and perception of the sounds of musical instruments. The first section introduces generic aspects of musical acoustics and the perception of musical sounds, followed by separate sections on string, wind and percussion instruments.

Gough, Colin

213

Acoustic Monitoring  

NSDL National Science Digital Library

The Acoustic Monitoring Project at NOAA is observing the ocean through underwater acoustics. At this site, visitors can learn about NOAA's studies in Bioacoustics, Ocean Seismicity, and Environmental Noise. The site also offers many animations dealing with Axial eruption, Atlantic Seismicity, and much more.

2013-08-23

214

Modeling of the quadratic non-Condon effect in the 4 f 135 d-4 f 14 luminescence spectrum of a LiYF4:Lu3+ crystal  

NASA Astrophysics Data System (ADS)

Based on a microscopic model of the electron-phonon interaction, we have calculated the shape of the 4 f 135 d-4 f 14 electronic-vibrational luminescence spectrum of a LiYF4:Lu3+ crystal at zero temperature taking into account the quadratic non-Condon effect. We have found that the magnitude of the quadratic non-Condon effect of this spectrum is several times greater than the magnitude of the linear non-Condon effect. We have formulated conditions under which the zero-phonon line can be observed in absorption and luminescence spectra of this transition, which is forbidden at zero temperature. It has been proven that, if the point symmetry group of the environment of an impurity center does not have mathematically irreducible representations with a dimension higher than unity, no zero-phonon line will be observed in these spectra. We have given an explanation for the absence of the zero-phonon line in 4 f 14-4 f 135 d absorption and luminescence spectra of the LiYF4:Lu3+ crystal at low temperatures.

Solovyev, O. V.; Yunusov, R. Yu.

2014-05-01

215

Impact of temperature on Na2 Sr(PO4)F:Eu3+ phosphor.  

PubMed

In this article, we report the synthesis of Na2 Sr1-x (PO4)F:Eux phosphor via a combustion method. The influence of different annealing temperatures on the photoluminescence properties was investigated. The phosphor was excited at both 254 and 393 nm. Na2 Sr1-x (PO4)F:Eux (3+) phosphors emit strong orange and red color at 593 and 612 nm, respectively, under both excitation wavelengths. Na2 Sr1-x (PO4)F:Eux (3+) phosphors annealed at 1050°C showed stronger emission intensity compared with 600, 900 and 1200°C. Moreover, Na2 Sr1-x (PO4)F:Eux (3+) phosphor was found to be more intense when compared with commercial Y2 O3:Eu(3+) phosphor. PMID:23853136

Shinde, K N; Pawade, V B; Dhoble, S J; Hakeem, A

2014-06-01

216

Characterization of the active site properties of CYP4F12.  

PubMed

Cytochrome P450 4F12 is a drug-metabolizing enzyme that is primarily expressed in the liver, kidney, colon, small intestine, and heart. The properties of CYP4F12 that may impart an increased catalytic selectivity (decreased promiscuity) were explored through in vitro metabolite elucidation, kinetic isotope effect experiments, and computational modeling of the CYP4F12 active site. By using astemizole as a probe substrate for CYP4F12 and CYP3A4, it was observed that although CYP4F12 favored astemizole O-demethylation as the primary route of metabolism, CYP3A4 was capable of metabolizing astemizole at multiple sites on the molecule. Deuteration of astemizole at the site of O-demethylation resulted in an isotope effect of 7.1 as well as an 8.3-fold decrease in the rate of clearance for astemizole by CYP4F12. Conversely, although an isotope effect of 3.8 was observed for the formation of the O-desmethyl metabolite when deuterated astemizole was metabolized by CYP3A4, there was no decrease in the clearance of astemizole. Development of a homology model of CYP4F12 based on the crystal structure of cytochrome P450 BM3 predicted an active site volume for CYP4F12 that was approximately 76% of the active site volume of CYP3A4. As predicted, multiple favorable binding orientations were available for astemizole docked into the active site of CYP3A4, but only a single binding orientation with the site of O-demethylation oriented toward the heme was identified for CYP4F12. Overall, it appears that although CYP4F12 may be capable of binding similar ligands to other cytochrome P450 enzymes such as CYP3A4, the ability to achieve catalytically favorable orientations may be inherently more difficult because of the increased steric constraints of the CYP4F12 active site. PMID:25074871

Eksterowicz, John; Rock, Dan A; Rock, Brooke M; Wienkers, Larry C; Foti, Robert S

2014-10-01

217

Acoustic-emission linear-pulse holography  

SciTech Connect

This paper describes Acoustic Emission Linear Pulse Holography which combines the advantages of linear imaging and acoustic emission into a single NDE inspection system. This unique system produces a chronological linear holographic image of a flaw by utilizing the acoustic energy emitted during crack growth. Conventional linear holographic imaging uses an ultrasonic transducer to transmit energy into the volume being imaged. When the crack or defect reflects that energy, the crack acts as a new source of acoustic waves. To formulate an image of that source, a receiving transducer is scanned over the volume of interest and the phase of the received signals is measured at successive points on the scan. The innovation proposed here is the utilization of the crack generated acoustic emission as the acoustic source and generation of a line image of the crack as it grows. A thirty-two point sampling array is used to construct phase-only linear holograms of simulated acoustic emission sources on large metal plates. The phases are calculated using the pulse time-of-flight (TOF) times from the reference transducer to the array of receivers. Computer reconstruction of the image is accomplished using a one-dimensional FFT algorithm (i.e., backward wave). Experimental results are shown which graphically illustrate the unique acoustic emission images of a single point and a linear crack in a 100 mm x 1220 mm x 1220 mm aluminum plate.

Collins, H.D.; Lemon, D.K.; Busse, L.J.

1982-06-01

218

Web Ecology: Recycling HTML Pages as XML Documents Using W4F  

Microsoft Academic Search

In this paper we present the World-Wide Web Wrapper Factory(W4F), a Java toolkit to generate wrappers for Webdata sources. Some key features of W4F are an expressivelanguage to extract information from HTML pages in astructured way, a mapping to export it as XML documentsand some visual tools to assist the user during wrapper creation.Moreover, the entire description of wrappers is

Arnaud Sahuguet; Fabien Azavant

1999-01-01

219

L-4F treatment reduces adiposity, increases adiponectin levels, and improves insulin sensitivity in obese mice  

Microsoft Academic Search

We hypothesized that the apolipoprotein mimetic peptide L-4F, which induces arterial anti-oxidative enzymes and is vasoprotective in a rat model of diabetes, would ame- liorate insulin resistance and diabetes in obese mice. L-4F (2 mg\\/kg\\/d) administered to ob\\/ob mice for 6 weeks lim- ited weight gain without altering food intake, decreased visceral (P , 0.02) and subcutaneous (P , 0.045)

Stephen J. Peterson; George Drummond; Dong Hyun Kim; Ming Li; Adam L. Kruger; Susumu Ikehara; Nader G. Abraham

2008-01-01

220

Investigations of electron attachment to the perfluorocarbon molecules c-C4F8, 2-C4F8, 1,3 C4F6, and c-C5F8  

NASA Astrophysics Data System (ADS)

Non-dissociative and dissociative electron attachment to a series of gas-phase perfluorocarbons (PFCs), namely octafluorocyclobutane, c-C4F8, octafluorobut-2-ene (perfluoro-2-butene), 2-C4F8, hexafluorobuta-1,3-diene (1,3 perfluorobutadiene), 1,3 C4F6, and octafluorocyclopentene (perfluorocyclopentene), c-C5F8, of importance to technological plasmas, have been investigated using two different, but complimentary, instruments available in Innsbruck over the electron energy range 0-20 eV. Anion yields as a function of electron energy have been recorded, with the positions and intensities of the electron attachment resonances being determined. One of these instruments is a double focusing sector field mass spectrometer (VG-ZAB-2SEQ), which has been used for measurements requiring high sensitivity and for obtaining accurate relative anion yields. It has also been used to determine the electron detachment lifetimes of the parent anions under various accelerating voltages, and these results are also presented. The second instrument (CELIA) is a trochoidal electron monochromator coupled to a quadrupole mass filter with a pulse counting system for detecting product anionic species. This provides a much higher energy resolution than the VG-ZAB, which makes it a better instrument to investigate narrow energy resonances close to 0 eV. The results of anion yields, peak positions and the relative intensities presented in this paper are compared with previous data of electron attachment to the above PFCs, including investigations by Professor Eugen Illenberger.

Feil, Stefan; Märk, Tilmann D.; Mauracher, Andreas; Scheier, Paul; Mayhew, Chris A.

2008-11-01

221

146 IEEE TRANSACTIONS ON PLASMA SCIENCE, VOL. 27, NO. 1, FEBRUARY 1999 Video Imaging of Dust Acoustic Waves  

E-print Network

). The bluish-red glow is the light emission from the plasma. The entire image covers 640 (vertical) pixels for this mode, it is typically of extremely low frequency tens of Hz). This low frequency, along with the light scatters light, allowing easy imaging of the cloud with the use of a simple video camera. For this image

Merlino, Robert L.

222

Imaging slow failure in triaxially deformed Etna basalt using 3D acoustic-emission location and X-ray computed tomography  

NASA Astrophysics Data System (ADS)

We have deformed basalt from Mount Etna (Italy) in triaxial compression tests under an effective confining pressure representative of conditions under a volcanic edifice (40 MPa), and at a constant strain rate of 5 × 10-6 s-1. Despite containing a high level of pre-existing microcrack damage, Etna basalt retains a high strength of 475 MPa. We have monitored the complete deformation cycle through contemporaneous measurements of axial strain, pore volume change, compressional wave velocity change and acoustic emission (AE) output. We have been able to follow the complete evolution of the throughgoing shear fault without recourse to any artificial means of slowing the deformation. Locations of AE events over time yields an estimate of the fault propagation velocity of between 2 and 4 mm.s-1. We also find excellent agreement between AE locations and post-test images from X-ray microtomography scanning that delineates deformation zone architecture.

Benson, Philip M.; Thompson, Ben D.; Meredith, Philip G.; Vinciguerra, Sergio; Young, R. Paul

2007-02-01

223

Properties of c-C4F8 inductively coupled plasmas. II. Plasma chemistry and reaction mechanism for modeling of Arc-C4F8 O2 discharges  

E-print Network

Properties of c-C4F8 inductively coupled plasmas. II. Plasma chemistry and reaction mechanism of the plasma chemistry of inductively coupled plasmas ICPs sustained in Ar, O2 , Ar/c-C4F8 and O2 /c-C4F8 gas , and CO are often used for the plasma etching of silicon dioxide. Gas phase reaction mechanisms

Kushner, Mark

224

Music Acoustics  

NSDL National Science Digital Library

The Music Acoustics Web site is maintained by the University of New South Wales School of Physics. General topics covered include what a decibel is, what interference beats are, what a sound spectrum is, what acoustic impedance is, and others. Specific instrument questions are also answered, such as waves in strings, flute and clarinet acoustics, Helmholz resonance, and pipes and harmonics. This very interesting site, with its many illustrations and animations, along with its easily-read text, answers all the questions you've ever had on the physics of music and many of the ones you never knew you wanted to ask.

1997-01-01

225

Acoustic images of the submarine fan system of the northern Kumano Basin obtained during the experimental dives of the Deep Sea AUV URASHIMA  

NASA Astrophysics Data System (ADS)

Autonomous underwater vehicles (AUVs) present the important advantage of being able to approach the seafloor more closely than surface vessel surveys can. To collect bathymetric data, bottom material information, and sub-surface images, multibeam echosounder, sidescan sonar (SSS) and subbottom profiler (SBP) equipment mounted on an AUV are powerful tools. The 3000m class AUV URASHIMA was developed by the Japan Agency for Marine-Earth Science and Technology (JAMSTEC). After finishing the engineering development and examination phase of a fuel-cell system used for the vehicle's power supply system, a renovated lithium-ion battery power system was installed in URASHIMA. The AUV was redeployed from its prior engineering tasks to scientific use. Various scientific instruments were loaded on the vehicle, and experimental dives for science-oriented missions conducted from 2006. During the experimental cruise of 2007, high-resolution acoustic images were obtained by SSS and SBP on the URASHIMA around the northern Kumano Basin off Japan's Kii Peninsula. The map of backscatter intensity data revealed many debris objects, and SBP images revealed the subsurface structure around the north-eastern end of our study area. These features suggest a structure related to the formation of the latest submarine fan. However, a strong reflection layer exists below ~20ms below the seafloor in the south-western area, which we interpret as a denudation feature, now covered with younger surface sediments. We continue to improve the vehicle's performance, and expect that many fruitful results will be obtained using URASHIMA.

Kasaya, Takafumi; Kanamatsu, Toshiya; Sawa, Takao; Kinosita, Masataka; Tukioka, Satoshi; Yamamoto, Fujio

2011-02-01

226

System and method to create three-dimensional images of non-linear acoustic properties in a region remote from a borehole  

DOEpatents

In some aspects of the disclosure, a method for creating three-dimensional images of non-linear properties and the compressional to shear velocity ratio in a region remote from a borehole using a conveyed logging tool is disclosed. In some aspects, the method includes arranging a first source in the borehole and generating a steered beam of elastic energy at a first frequency; arranging a second source in the borehole and generating a steerable beam of elastic energy at a second frequency, such that the steerable beam at the first frequency and the steerable beam at the second frequency intercept at a location away from the borehole; receiving at the borehole by a sensor a third elastic wave, created by a three wave mixing process, with a frequency equal to a difference between the first and second frequencies and a direction of propagation towards the borehole; determining a location of a three wave mixing region based on the arrangement of the first and second sources and on properties of the third wave signal; and creating three-dimensional images of the non-linear properties using data recorded by repeating the generating, receiving and determining at a plurality of azimuths, inclinations and longitudinal locations within the borehole. The method is additionally used to generate three dimensional images of the ratio of compressional to shear acoustic velocity of the same volume surrounding the borehole.

Vu, Cung; Nihei, Kurt T.; Schmitt, Denis P.; Skelt, Christopher; Johnson, Paul A.; Guyer, Robert; TenCate, James A.; Le Bas, Pierre-Yves

2013-01-01

227

Room Acoustics  

NASA Astrophysics Data System (ADS)

The traditional task of room acoustics is to create or formulate conditions which ensure the best possible propagation of sound in a room from a sound source to a listener. Thus, objects of room acoustics are in particular assembly halls of all kinds, such as auditoria and lecture halls, conference rooms, theaters, concert halls or churches. Already at this point, it has to be pointed out that these conditions essentially depend on the question if speech or music should be transmitted; in the first case, the criterion for transmission quality is good speech intelligibility, in the other case, however, the success of room-acoustical efforts depends on other factors that cannot be quantified that easily, not least it also depends on the hearing habits of the listeners. In any case, absolutely "good acoustics" of a room do not exist.

Kuttruff, Heinrich; Mommertz, Eckard

228

Proceedings of the Stockholm Music Acoustics Conference, August 6-9, 2003 (SMAC 03), Stockholm, Sweden USING IMAGING AND MODELING TECHNIQUES TO UNDERSTAND THE RELATION  

E-print Network

Proceedings of the Stockholm Music Acoustics Conference, August 6-9, 2003 (SMAC 03), Stockholm TO ACOUSTIC CHARACTERISTICS Brad H. Story Department of Speech and Hearing Sciences University of Arizona of the vocal tract as a versatile acoustic device capable of producing a wide range of possible vowel and vowel

Story, Brad H.

229

E4F1 is essential for epidermal stem cell maintenance and skin homeostasis Matthieu Lacroix1, 3, 4, 10, &  

E-print Network

1 E4F1 is essential for epidermal stem cell maintenance and skin homeostasis Matthieu Lacroix1, 3: Role of E4F1 in skin homeostasis Key words: E4F1, p53, knock-out, epidermal stem cells, skin inserm in the entire skin or in the basal compartment of the epidermis induces skin homeostasis defects, as evidenced

Boyer, Edmond

230

Acoustic neuromas  

Microsoft Academic Search

Opinion statement  Patients with acoustic neuromas have several treatment options that include observation, surgical resection, stereotactic\\u000a radiosurgery, and fractionated radiotherapy. Resection is indicated for patients with larger tumors that have caused major\\u000a neurologic deficits from brain compression. Surgeons perform stereotactic radiosurgery as the main alternative to acoustic\\u000a tumor resection with the goals of preserved neurologic function and prevention of tumor growth.

Douglas Kondziolka; L. Dade Lunsford; John C. Flickinger

2002-01-01

231

Acoustic Schwannoma  

Microsoft Academic Search

\\u000a Acoustic schwannomas are benign tumors that originate from Schwann cells surrounding the vestibular (eighth) nerve, usually\\u000a within the internal auditory canal [1]. As the tumor enlarges, it fills the canal and extends into the cerebellopontine angle. Acoustic schwannomas are relatively\\u000a uncommon with an incidence of approximately 1 new case per 100,000 [1]. The mean age at diagnosis is approximately 45

William M. Mendenhall; Robert J. Amdur; Robert S. Malyapa; William A. Friedman

232

Acoustic measurement of the Deepwater Horizon Macondo well flow rate  

E-print Network

On May 31, 2010, a direct acoustic measurement method was used to quantify fluid leakage rate from the Deepwater Horizon Macondo well prior to removal of its broken riser. This method utilized an acoustic imaging sonar and ...

Camilli, Richard

233

Model for an inductively coupled Ar/c-C4F8 plasma discharge  

NASA Astrophysics Data System (ADS)

This article describes a two-dimensional model for an inductively coupled Ar/c-C4F8 plasma discharge, which is widely used in the microelectronics industry for dielectric etching and polymerization. The chemical mechanism for c-C4F8 incorporates known information about electron impact dissociation, ionization, and attachment processes. Unknown details such as neutral dissociation byproducts have been empirically inferred using energetics analysis or diagnostic experiments. The mechanism also considers electron impact processes for neutral radicals (e.g., CF, CF2, CF3) and stable molecules (e.g., C2F4) produced in a c-C4F8 plasma. It is demonstrated in the article that the resulting neutral species densities, ion flux to the wafer, and electron characteristics are in good agreement with experiments in the Gaseous Electronics Conference reference cell. The validated model is used to understand the dynamics of an inductively coupled Ar/c-C4F8 plasma discharge, and the impact of various control parameters on plasma characteristics. Results indicate that CF2 is the dominant CFx radical in the c-C4F8 discharge and the plasma is mildly electronegative. Enhanced ionization and dissociation of c-C4F8 with increasing inductive power deposition leads to an increase in electron and CFx radical densities, and total ion flux to the wafer. Enhanced dissociative attachment at higher gas pressure decreases the electron density and increases the negative ion density. The plasma becomes more electropositive with decreasing c-C4F8 concentration in the gas mixture, which increases the total positive ion flux to the wafer.

Rauf, Shahid; Ventzek, Peter L. G.

2002-01-01

234

Acoustic emission linear pulse holography  

DOEpatents

Defects in a structure are imaged as they propagate, using their emitted acoustic energy as a monitored source. Short bursts of acoustic energy propagate through the structure to a discrete element receiver array. A reference timing transducer located between the array and the inspection zone initiates a series of time-of-flight measurements. A resulting series of time-of-flight measurements are then treated as aperture data and are transferred to a computer for reconstruction of a synthetic linear holographic image. The images can be displayed and stored as a record of defect growth.

Collins, H. Dale (Richland, WA); Busse, Lawrence J. (Richland, WA); Lemon, Douglas K. (West Richland, WA)

1985-01-01

235

Acoustic emission linear pulse holography  

SciTech Connect

Defects in a structure are imaged as they propagate, using their emitted acoustic energy as a monitored source. Short bursts of acoustic energy propagate through the structure to a discrete element receiver array. A reference timing transducer located between the array and the inspection zone initiates a series of time-of-flight measurements. A resulting series of time-of-flight measurements are then treated as aperture data and are transferred to a computer for reconstruction of a synthetic linear holographic image. The images can be displayed and stored as a record of defect growth.

Collins, H. D.; Busse, L. J.; Lemon, D. K.

1985-07-30

236

Some aspects of configuration interaction of the 4f(n) configurations of tripositive lanthanide ions.  

PubMed

Some features of the interaction of the 4f(N) configuration of tripositive lanthanide ions (Ln(3+)) with excited configurations have been investigated. The calculated barycenter energies of the same parity 4f(N-1)6p, 4f(N+1)5p(5), and 4f(N-1)5f configurations for Ln(3+), relative to those of 4f(N), are fitted well by exponential functions. The 4f(N) barycenter energies of Ln(3+) in Y3Al5O12/Ln(3+) lie in the band gap, with the exceptions of Tb(3+) and Yb(3+), where they are situated in the conduction and valence bands, respectively. The configuration interaction parameters ?, ?, and ?, which are fitted in the usual phenomenological Hamiltonian to calculate the crystal field energies of Ln(3+), exhibit quite variable magnitudes in the literature due to incomplete energy level data sets, energy level misassignments and fitting errors. For LaCl3/Ln(3+), 83% of the variation of ? and 50% of that for ? can be explained by the change in the difference in barycenter energy with the predominant interacting configuration. The parameter ? is strongly correlated with the Slater parameter F(2) and is not well-determined in most calculations. The values of the electrostatically correlated spin-other orbit parameter P(2) vary smoothly across the Ln(3+) series with the barycenter difference between the 4f(N) and 4f(N-1)5f configurations. Calculations of the P(k) (k = 2, 4, and 6) values for Pr(3+) show that 4f ? nf excitations only account for ?65% of the value of P(2) for LaCl3/Pr(3+) and 35% of that in Y3Al5O12/Pr(3+). The role of the ligand is therefore important in determining the value, and a discussion is included of the present state of configuration-interaction-assisted crystal field calculations. Further progress cannot be made in the above areas until more reliable and complete energy level data sets are available for the Ln(3+) series of ions in crystals. PMID:25171085

Tanner, Peter A; Yeung, Yau-Yuen; Ning, Lixin

2014-09-25

237

Isomer effects on the total cross section for electron scattering from C4F6 molecules  

NASA Astrophysics Data System (ADS)

The absolute total cross section (TCS) for electron scattering from hexafluoro-1,3-butadiene (1,3-C4F6) was obtained in a transmission experiment for electron impact energies from 0.6 to 370 eV. The TCS energy function has two pronounced enhancements separated by a deep minimum located near 2.6 eV: a low-energy hump around 1 eV and a dominant very broad enhancement centred near 30 eV. The 1,3-C4F6 TCS results are compared with the data for hexafluoro-2-butyne (2-C4F6) and the influence of the structural differences on the electron-scattering TCS for isomers of the C4F6 molecule (isomeric effect) is explicitly indicated. The most pronounced role of the molecular geometry on the magnitude and shape of the TCS energy dependence is observed at the lowest energies studied. Above 40 eV the TCSs for both isomers are close to each other. Some conformities of TCSs within a series of perfluorocarbons (C2F4, 1,3-C4F6, C6F6) as well as in a series of their hydrocarbon counterparts (C2H4, 1,3-C4H6, C6H6) are also pointed out and discussed.

Szmytkowski, Czeslaw; Kwitnewski, Stanislaw

2003-12-01

238

Preservation of biological function despite oxidative modification of the apolipoprotein A-I mimetic peptide 4F  

PubMed Central

Myeloperoxidase (MPO)-derived hypochlorous acid induces changes in HDL function via redox modifications at the level of apolipoprotein A-I (apoA-I). As 4F and apoA-I share structural and functional properties, we tested the hypothesis that 4F acts as a reactive substrate for hypochlorous acid (HOCl). 4F reduced the HOCl-mediated oxidation of the fluorescent substrate APF in a concentration-dependent manner (ED50 ? 56 ± 3 ?M). This reaction induced changes in the physical properties of 4F. Addition of HOCl to 4F at molar ratios ranging from 1:1 to 3:1 reduced 4F band intensity on SDS-PAGE gels and was accompanied by the formation of a higher molecular weight species. Chromatographic studies showed a reduction in 4F peak area with increasing HOCl and the formation of new products. Mass spectral analyses of collected fractions revealed oxidation of the sole tryptophan (Trp) residue in 4F. 4F was equally susceptible to oxidation in the lipid-free and lipid-bound states. To determine whether Trp oxidation influenced its apoA-I mimetic properties, we monitored effects of HOCl on 4F-mediated lipid binding and ABCA1-dependent cholesterol efflux. Neither property was altered by HOCl. These results suggest that 4F serves as a reactive substrate for HOCl, an antioxidant response that does not influence the lipid binding and cholesterol effluxing capacities of the peptide. PMID:22589558

White, C. Roger; Datta, Geeta; Buck, Amanda K. W.; Chaddha, Manjula; Reddy, Gautam; Wilson, Landon; Palgunachari, Mayakonda N.; Abbasi, Mohammad; Anantharamaiah, G. M.

2012-01-01

239

Phase transition studies of sodium deintercalated Na2-xFePO4F (0 ? x ? 1) by Mössbauer spectroscopy  

NASA Astrophysics Data System (ADS)

The phase transition in sodium deintercalated Na2-xFePO4F (0 ? x ? 1) polycrystalline samples was studied by x-ray diffraction and Mössbauer spectroscopy. Sodium deintercalated samples were obtained by chemical deintercalation of pure Na2FePO4F. From the refined x-ray diffraction patterns, the crystalline structure of Na2FePO4F was determined to be orthorhombic with the space group Pbcn. The structure of fully sodium deintercalated NaFePO4F is identical to that of pure Na2FePO4F, differing only in the cell parameters. The changes in the unit cell parameters and atomic positions in Na2-xFePO4F (x = 0, 1) samples originated from a Na2 ion deficiency in the interlayer spaces. The room-temperature Mössbauer spectra of Na2-xFePO4F (x = 0, 1) were fitted with one set of the Fe2+ /3+ doublets. A decrease in the absorption area of Fe2 + in Na2FePO4F with increasing sodium deintercalation was observed in the Mössbauer spectra of Na2-xFePO4F, whereas the area of the Fe3+ doublet in NaFePO4F increased. The large value of ?EQ for the Fe2+ doublet phase was due to the asymmetric charge distribution of FeO4F2 arising from different lattice and valence state contributions.

Lee, In Kyu; Shim, In-Bo; Kim, Chul Sung

2011-04-01

240

A Mössbauer spectroscopy study of polyol synthesized tavorite LiFeSO4F  

NASA Astrophysics Data System (ADS)

The tavorite polymorph of LiFeSO4F has attracted considerable attention as a cathode material for lithium ion batteries due to interesting structural and electrochemical characteristics. For the analysis of such iron-based electrode materials, Mössbauer spectroscopy has become an important and highly useful tool. In this work, we perform a detailed Mössbauer study of pristine tavorite LiFeSO4F prepared by an optimized synthesis in tetraethylene glycol as reaction media. In contrast to many reported results, we demonstrate the use of an asymmetric fitting model for the inner doublet of the spectrum, which is coupled to the structural properties of the compound. Moreover, we discuss a new approach of ascribing the Fe2 + -doublets to the two distinct crystallographic iron sites of tavorite LiFeSO4F by comparing the Mössbauer signal intensities with the expected f-factors for the corresponding iron atom.

Sobkowiak, Adam; Ericsson, Tore; Edström, Kristina; Gustafsson, Torbjörn; Björefors, Fredrik; Häggström, Lennart

2014-04-01

241

?-Hydroxylation of phylloquinone by CYP4F2 is not increased by ?-tocopherol  

PubMed Central

Scope The objective of this study was to investigate the initial catabolic step of vitamin E and K metabolism, the ?-hydroxylation by human cytochrome P450 4F2 (CYP4F2). Methods and Results Tocopherol (T) metabolism was compared using rat liver slices incubated with deuterated (d6)-RRR-?-T (d6-?-T), racemic 2S-?-T (2S, 4’RS, 8’RS ?-T, 2S-?-T), or d2-?-T (d2-?-T). Following comparable uptake of each T by liver slices, twice as much 13’-OH-T was produced from 2S-?-T or d2-?-T (39 ± 15 or 42 ± 5 pmol/g liver, respectively) as from d6-?-T (17 ± 2, p<0.01). Kinetic studies were conducted using insect microsomes expressing human CYP4F2 incubated with d4-phylloquinone (d4-PK), d6-RRR-?-T, d3-SRR-?-T, or d2-?-T. CYP4F2 demonstrated similar apparent maximal velocities (Vmax) when either of the ?-Ts were used as substrates, which were less than the apparent d4-PK Vmax (p<0.0002), while the CYP4F2 catalytic efficiency towards d4-PK (15.8 Vmax/Km) was 5-times greater than for ?-Ts. Vitamin K had no effect on vitamin E catabolism, while vitamin E slightly decreased the d4-PK Vmax. Conclusions CYP4F2 discriminates between Ts and PK in vitro, but ?-T does not apparently increase PK ?-hydroxylation by this mechanism. PMID:23650179

Farley, Sherry M.; Leonard, Scott W.; Taylor, Alan W.; Birringer, Marc; Edson, Katheryne Z.; Rettie, Allan E.; Traber, Maret G.

2013-01-01

242

SF6 and C4F8 global kinetic models coupled to sheath models  

NASA Astrophysics Data System (ADS)

Global kinetic models combined with Monte Carlo sheath models are developed for SF6 and C4F8 plasma discharges for silicon etching under the Bosch process. In SF6 plasma, the dominant positive ions are SF_5+ , SF_4+ , SF_3+ and F+ while in C4F8 the dominant positive ions are CF_3+ and C_2F_3+ . The simulation results show that the electrical parameters, such as the electron density and electron temperature, clearly affect the sheath dynamics and consequently the ion energy distribution function evolutions. In this context, we showed the effects of the operating conditions, such as the pressure and the radiofrequency power, on the electron density and electron temperature evolutions as well as the reactive particle fluxes (neutral and positive ions) involved in the plasma surface interactions for etching/deposition under the Bosch process. Ion energy distribution functions obtained from SF6 and C4F8 plasmas are compared with each other as regards the electrical properties of their associated plasmas. The simulation results show that the bimodal peaks of ion energy distribution functions are wider for SF6 plasma than for C4F8 plasma due to the high sheath thickness of SF6 compared to that of C4F8. This is explained by the low electron density due to the high electronegativity of SF6 in comparison to that of C4F8. The simulations also reveal that the bimodal peak of the ion energy distribution function is wider when the ion mass is low.

Haidar, Yehya; Pateau, Amand; Rhallabi, Ahmed; Fernandez, Marie Claude; Mokrani, Arezki; Taher, Fadia; Roqueta, Fabrice; Boufnichel, Mohamed

2014-12-01

243

Convergence of temporal and spectral information into acoustic images of complex sonar targets perceived by the echolocating bat, Eptesicus fuscus  

Microsoft Academic Search

Summary 1.FM echolocating bats (Eptesicus fuscus) were trained to discriminate between a two-component complex target and a one-component simple target simulated by electronically-returned echoes in a series of experiments that explore the composition of the image of the two-component target. In Experiment I, echoes for each target were presented sequentially, and the bats had to compare a stored image of

James A. Simmons; Cynthia F. Moss; Michael Ferragamo

1990-01-01

244

Syntheses and NMR study of 4f-spin-free electron-doped copper oxides  

Microsoft Academic Search

All the electron-doped high-Tc oxides discovered so far inevitably contain lanthanides, whose 4f-spin fluctuation hides all the NMR information on the superconductivity. The new copper oxide superconductor (La1-yYy)2-xCexCuO4 with T'-type structure, which is free from 4f-spins has been successfully synthesized. Obtained compounds showed a nearly zero electric field gradient(EFG) at Cu site, which demonstrates that the doped carrier is electronic.

Masatsugu Fukunaga; Takayuki Goto; Kazuya Miyagawa; Tetsuo Fukase

1994-01-01

245

Acoustic Characterization of Mesoscale Objects  

SciTech Connect

This report describes the science and engineering performed to provide state-of-the-art acoustic capabilities for nondestructively characterizing mesoscale (millimeter-sized) objects--allowing micrometer resolution over the objects entire volume. Materials and structures used in mesoscale objects necessitate the use of (1) GHz acoustic frequencies and (2) non-contacting laser generation and detection of acoustic waves. This effort demonstrated that acoustic methods at gigahertz frequencies have the necessary penetration depth and spatial resolution to effectively detect density discontinuities, gaps, and delaminations. A prototype laser-based ultrasonic system was designed and built. The system uses a micro-chip laser for excitation of broadband ultrasonic waves with frequency components reaching 1.0 GHz, and a path-stabilized Michelson interferometer for detection. The proof-of-concept for mesoscale characterization is demonstrated by imaging a micro-fabricated etched pattern in a 70 {micro}m thick silicon wafer.

Chinn, D; Huber, R; Chambers, D; Cole, G; Balogun, O; Spicer, J; Murray, T

2007-03-13

246

Energy position of 4f levels in rare-earth metals  

Microsoft Academic Search

The energy position of the occupied and unoccupied 4f levels relative to the Fermi energy is studied for the rare-earth metals. This is done by treating the excited state as an impurity in an otherwise perfect crystal. This picture is first considered in the complete screening approximation. In this approximation thermochemical data can be used directly to give energy values

Börje Johansson

1979-01-01

247

F68-4 F.M. RADIO STATION Legislative History  

E-print Network

F68-4 F.M. RADIO STATION Legislative History: Document dated November 21, 1968. At its meeting by Dr. Frederic Weed, Chairman of the Ad Hoc F.M. Radio Policy Committee, (amended November 18, 1968): ACTION BY COLLEGE PRESIDENT: "Approved." Signed: Robert D. Clark, December 6, 1968. F.M. RADIO STATION

Gleixner, Stacy

248

Thyroid hormone transport by 4F2hc-IU12 heterodimers expressed in Xenopus oocytes.  

PubMed

Thyroid hormone (TH) action and metabolism require hormone transport across cell membranes. We have investigated the possibility that TH are substrates of amino acid transport (System L) mediated by heterodimers of 4F2 heavy-chain (hc) and the light-chain (lc) permease IU12. Co-expression of 4F2hc and IU12 cDNAs injected into Xenopus oocytes induces saturable, Na(+) -independent transport of tri-iodothyronine (T(3)), thyroxine (T(4)) (K(m) of 1.8 and 6.3 microM respectively), tryptophan and phenylalanine. Induced TH and tryptophan uptakes are inhibited by excess BCH (synthetic System L substrate). Induced TH uptake is also inhibited by excess reverse tri-iodothyronine (rT(3)), but not by triodothyroacetic acid (TRIAC) (TH analogue lacking anamino acid moiety). T(3) and tryptophan exhibit reciprocal inhibition of their 4F2hc-IU12 induced uptake. Transport pathways produced by 4F2hc-lc permease complexes may therefore be important routes for movement and exchange of TH (as well as amino acids) across vertebrate cell membranes, with a potential role in modulating TH action. PMID:10556789

Ritchie, J W; Peter, G J; Shi, Y B; Taylor, P M

1999-11-01

249

Fine and hyperfine structure for 4f 115d6s6p in Er I  

NASA Astrophysics Data System (ADS)

Hyperfine structure (hfs) constants in neutral erbium of 22 levels of the configuration 4f115d6s6p with four open electron shells have been determined for the only stable odd isotope 167Er, using Doppler reduced saturation spectroscopy in form of intermodulated optogalvanic and saturated absorption spectroscopy. From the experimental data for altogether 29 levels we evaluated the hfs-parameters in the effective tensor operator formalism. For this purpose we performed a fine structure analysis of the sub-configuration 4f11(4I)5d6s6p in LS-coupling, confirming and extending the preliminary classification of even parity Er I levels. The relativistic magnetic and electric one-electron parameters were fitted to the experimental data by a least squares fit procedure: a4f01 = -156.6 (1.7) MHz, a5d01 = -30 (10) MHz, a6p01 = -114 (24) MHz, a6s10 = -1630 (35) MHz, b4f02 = -7960 (200) MHz, b5d02 = 3460 (180) MHz, b6p02 = 5440 (270) MHz, gave the best results in the case where all parameters of one electron shell were held in a fixed ratio. The corresponding langr-3rang nlkskl values are compared with those known for other lanthanide elements, extending the present systematic hyperfine studies. Finally, effective nuclear quadrupole moments have been determined and will be discussed.

Kronfeldt, H.-D.; Ashkenasi, D.; Kröger, S.; Wyart, J.-F.

1993-12-01

250

Improving the Battery Performance of LiVPO4F by Chromium Doping  

NASA Astrophysics Data System (ADS)

Polyanion LiVPO4F has been recently recognized as a promising high energy cathode material for next generation rechargeable lithium batteries. With the aim of performance advancement in this paper, 3 at.% chromium are used to dope LiVPO4F during carbothermal reduction synthesis. Rietveld refinement of X-ray diffraction pattern indicates that most of the chromium favors occupying the lithium site. Energy dispersive X-ray spectrum on selected area of the particle further demonstrates successful Cr doping into LiVPO4F. Both the rate capability and cycling performance of LiVPO4F are found noticeably improved possibly due to the stabilized crystalline structure and increased electric conductivity by Cr doping. The specific discharge capacities at C/24, C/5, 1 C and 8 C rates are 144.3, 135.1, 108.5 and 89.6 mA h g-1, respectively. Moreover, it delivers a capacity of 128.7 mA h g-1 at C/2 with the retention of 88.2% after 100 cycles.

Liu, Yanghao; Xu, Youlong; Sun, Xiaofei

2013-12-01

251

Chemical Treatment Effect of Si(111) Surfaces in NH4F Solution Studied by Spectroscopic Ellipsometry  

Microsoft Academic Search

Chemically treated Si(111) surfaces in NH4F (40%) solution at 20° C have been studied using spectroscopic ellipsometry (SE) and exsitu atomic force microscopy (AFM). The SE data clearly indicate that the solution causesthe removal of the native oxide with an etch rate of ˜ 15 Å\\/min. Just after the native oxide is etched away completely (t˜ 70 s), the SE

Takahiro Suzuki; Sadao Adachi

1994-01-01

252

Electron Interactions With c-C4F8 L. G. Christophoroua...  

E-print Network

Electron Interactions With c-C4F8 L. G. Christophoroua... and J. K. Olthoffb... Electricity Division, Electronics and Electrical Engineering Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-8113 Received 29 January 2001; accepted 26 March 2001 The limited electron

Magee, Joseph W.

253

Warming Potential Reduction of C4F8 Using Inductively Coupled Plasma  

NASA Astrophysics Data System (ADS)

The global warming potential (GWP) reduction of the perfluorinated compound (PFC) semiconductor manufacturing gas, C4F8, has been studied in an inductively coupled high-frequency (13.56 MHz) plasma system operating under multimode antenna. Mass spectral analysis of the decomposed species showed that major ionic species in the present study were (CFx+ (x=1,3) and C2F4+). Weak signals of CF4+ ions were detected for the first time in a C4F8 plasma. The behavior of the CF4+, C2F4+ and CF3+ ion peaks at various gas pressures (1-50 mTorr) and the effect of additive oxygen on the decomposition of the parent gas and CF4 have been presented. The mechanism of electron energy control was proposed for the effective decomposition of the C4F8 gas. The overall results showed that, at a higher azimuthal mode of antenna (m=1) the C4F8 decomposition and its GWP reduction was significant and it was considered to be due to the electron energy control at that mode.

Raju, Ramasamy; Kudo, Daisuke; Kubo, Yuya; Inaba, Tsuginori; Shindo, Haruo

2003-01-01

254

APPLICATION OF PULSE COMPRESSION SIGNAL PROCESSING TECHNIQUES TO ELECTROMAGNETIC ACOUSTIC TRANSDUCERS (EMATS) FOR NON-CONTACT THICKNESS MEASUREMENTS AND IMAGING  

Microsoft Academic Search

A pair of non-contact EMATs has been used for thickness measurements and imaging of metallic plates. This was performed using wide bandwidth EMATs and pulse- compression signal processing techniques, using chirp excitation. This gives a greatly improved Signal to Noise Ratio (SNR) for non-contact experiments, increasing the speed of data acquisition. A numerical simulation of the technique has confirmed the

T. H. Gan; K. S. Ho; D. A. Hutchins; D. R. Billson

255

Investigation of the Near-Field Acoustic and Flow Properties of Imperfectly Expanded Supersonic Jets using Particle Image Velocimetry  

Microsoft Academic Search

The flow fields of imperfectly Expanded Supersonic Jets from conical CD nozzles are investigated by Particle Image Velocimetry. This nozzle geometry represents the exhaust nozzles on high-performance military engines. The results are compared with shadowgraph to bring out the details of the highly accelerated regions where seed particles may lag behind the flow, viz. the shocks and Prandtl-Meyer fans. Nozzles

Ephraim Gutmark; David Munday; Junhui Liu; K. Kailasanath

2008-01-01

256

Design for Underwater Aplanatic Acoustic Mirror  

Microsoft Academic Search

Underwater acoustic lenses are useful devices for underwater imaging because of their small dimension and low power consumption but have a problem under the condition of changing water temperature because the refractive index depends on the water temperature. To solve this problem, we propose aplanatic acoustic mirrors, which consist of two aspherical mirrors and can remove spherical and coma aberrations.

Yuji Sato; Koichi Mizutani; Naoto Wakatsuki; Toshiaki Nakamura

2010-01-01

257

Dissociation Channels of c-C4F8 to CF2 Radical in Reactive Plasma  

NASA Astrophysics Data System (ADS)

It has been generally assumed that octafluorocyclobutane (c-C4F8) is mainly decomposed to CF2 via C2F4 in etching process plasma. However, the detailed mechanism for the dissociations is yet ambiguous. In this paper we have calculated the probable dissociation pathways by using ab initio molecular orbital method. The results show that c-C4F8 is dissociated via the first triplet excited state T1(3A2), the fourth triplet excited state T4(32E) and the fourth singlet excited state S4(12E). One of the degenerate excited states of T4 and S4 is constituted by antibonding combination of two ? bonding orbital of C2F4. T1 state is constituted by antibonding combination of b1u antibonding ? orbital of C2F4. Therefore, in the case of the dissociation via S4 and T4 excited states c-C4F8 may dissociate to two C2F4, and in the case of the dissociation via T1 excited state c-C4F8 may dissociate to four CF2 radicals. It is also found that C3F5+ ion observed as the main peak in c-C4F8 process plasma is produced by electron collision with the slightly larger energy than the ionization threshold value. The main dissociation path of C2F4 is a vertical electron attachment. However, it is also found that dissociation pathways via 1B2g, 3B1u, and 3B2g excited states are very important and should not be ignored.

Hayashi, Toshio; Ishikawa, Kenji; Sekine, Makoto; Hori, Masaru; Kono, Akihiro; Suu, Koukou

2011-03-01

258

Bioengineering 280A Principles of Biomedical Imaging  

E-print Network

scattering). Attenuation Loss of acoustic energy during propagation. Conversion of acoustic energy Z Also called acoustic energy flux. Analogous to electric power Echos Specular Reflection vi Imaging #12;4 Seutens 2002 PW Doppler Imaging Seutens 2002 Color Doppler Imaging Acoustic Waves

Liu, Thomas T.

259

Evaluation of damage accumulation behavior and strength anisotropy of NITE SiC/SiC composites by acoustic emission, digital image correlation and electrical resistivity monitoring  

NASA Astrophysics Data System (ADS)

Understanding the cracking process of the composites is essential to establish the design basis for practical applications. This study aims to investigate the damage accumulation process and its anisotropy for nano-infiltration transient eutectic sintered (NITE) SiC/SiC composites by various characterization techniques such as the acoustic emission (AE), digital image correlation (DIC) and electrical resistivity (ER) measurements. Cracking behavior below the proportional limit stress (PLS) was specifically addressed. Similar to the other generic SiC/SiC composites, the 1st AE event was identified below the PLS for NITE SiC/SiC composites with a dependency of fabric orientation. The DIC results support that the primary failure mode depending on fiber orientation affected more than the other minor modes did. Detailed AE waveform analysis by wavelet shows a potential to classify the failure behavior depending on architecture. Cracking below the PLS is a potential concern in component deign but the preliminary ER measurements imply that the impact of cracking below the PLS on composite function was limited.

Nozawa, Takashi; Ozawa, Kazumi; Asakura, Yuuki; Kohyama, Akira; Tanigawa, Hiroyasu

2014-12-01

260

Quantitative Thermo-acoustics and related problems Guillaume Bal  

E-print Network

Quantitative Thermo-acoustics and related problems Guillaume Bal Department of Applied Physics of Mathematics, University of Washington, Seattle, WA 98195 E-mail: tzhou@math.washington.edu Abstract. Thermo-acoustic in tissues with the good resolution properties of ultrasounds. Thermo-acoustic imaging may be decomposed

Bal, Guillaume

261

Quantitative Thermo-acoustics and related problems Guillaume Bal  

E-print Network

Quantitative Thermo-acoustics and related problems Guillaume Bal Department of Applied Physics of Mathematics, University of Washington, Seattle, WA 98195 E-mail: tzhou@math.washington.edu Abstract. Thermo-acoustic in tissues with the good resolution properties of ultrasound. Thermo-acoustic imaging may be decomposed

Ren, Kui

262

Physical and Engineering Acoustics 17 uation,10,11  

E-print Network

Physical and Engineering Acoustics 17 uation,10,11 and seismic imaging12,13 (see selected be shown that TR can be used to locate acoustic emission events, as work-in-progress continues acoustics, with applications in nondestructive evaluation, machine and structural monitoring, tracking

263

Acoustic transducer for acoustic microscopy  

DOEpatents

A shear acoustic transducer-lens system in which a shear polarized piezoelectric material excites shear polarized waves at one end of a buffer rod having a lens at the other end which excites longitudinal waves in a coupling medium by mode conversion at selected locations on the lens.

Khuri-Yakub, Butrus T. (Palo Alto, CA); Chou, Ching H. (Palo Alto, CA)

1990-01-01

264

Implementation and Comparison of Acoustic Travel-Time Measurement Procedures for the Helioseismic and Magnetic Imager Time-Distance Helioseismology Pipeline  

NASA Technical Reports Server (NTRS)

The Helioseismic and Magnetic Imager (HMI) instrument on board the Solar Dynamics Observatory (SDO) satellite is designed to produce high-resolution Doppler velocity maps of oscillations at the solar surface with high temporal cadence. To take advantage of these high-quality oscillation data, a time-distance helioseismology pipeline has been implemented at the Joint Science Operations Center (JSOC) at Stanford University. The aim of this pipeline is to generate maps of acoustic travel times from oscillations on the solar surface, and to infer subsurface 3D flow velocities and sound-speed perturbations. The wave travel times are measured from cross covariances of the observed solar oscillation signals. For implementation into the pipeline we have investigated three different travel-time definitions developed in time-distance helioseismology: a Gabor wavelet fitting (Kosovichev and Duvall, 1997), a minimization relative to a reference cross-covariance function (Gizon and Birch, 2002), and a linearized version of the minimization method (Gizon and Birch, 2004). Using Doppler velocity data from the Michelson Doppler Imager (MDI) instrument on board SOHO, we tested and compared these definitions for the mean and difference travel-time perturbations measured from reciprocal signals. Although all three procedures return similar travel times in a quiet Sun region, the method of Gizon and Birch (2004) gives travel times that are significantly different from the others in a magnetic (active) region. Thus, for the pipeline implementation we chose the procedures of Kosovichev and Duvall (1997) and Gizon and Birch (2002). We investigated the relationships among these three travel-time definitions, their sensitivities to fitting parameters, and estimated the random errors they produce

Couvidat, S.; Zhao, J.; Birch, A. C.; Kosovichev, A. G.; Duvall, T. L., Jr.; Parchevsky, K.; Scherrer, P. H.

2009-01-01

265

Implementation and Comparison of Acoustic Travel-Time Measurement Procedures for the Solar Dynamics Observatory-Helioseismic and Magnetic Imager Time-Distance Helioseismology Pipeline  

NASA Technical Reports Server (NTRS)

The Helioseismic and Magnetic Imager (HMI) instrument onboard the Solar Dynamics Observatory (SDO) satellite is designed to produce high-resolution Doppler-velocity maps of oscillations at the solar surface with high temporal cadence. To take advantage of these high-quality oscillation data, a time - distance helioseismology pipeline (Zhao et al., Solar Phys. submitted, 2010) has been implemented at the Joint Science Operations Center (JSOC) at Stanford University. The aim of this pipeline is to generate maps of acoustic travel times from oscillations on the solar surface, and to infer subsurface 3D flow velocities and sound-speed perturbations. The wave travel times are measured from cross-covariances of the observed solar oscillation signals. For implementation into the pipeline we have investigated three different travel-time definitions developed in time - distance helioseismology: a Gabor-wavelet fitting (Kosovichev and Duvall, SCORE'96: Solar Convection and Oscillations and Their Relationship, ASSL, Dordrecht, 241, 1997), a minimization relative to a reference cross-covariance function (Gizon and Birch, Astrophys. J. 571, 966, 2002), and a linearized version of the minimization method (Gizon and Birch, Astrophys. J. 614, 472, 2004). Using Doppler-velocity data from the Michelson Doppler Imager (MDI) instrument onboard SOHO, we tested and compared these definitions for the mean and difference traveltime perturbations measured from reciprocal signals. Although all three procedures return similar travel times in a quiet-Sun region, the method of Gizon and Birch (Astrophys. J. 614, 472, 2004) gives travel times that are significantly different from the others in a magnetic (active) region. Thus, for the pipeline implementation we chose the procedures of Kosovichev and Duvall (SCORE'96: Solar Convection and Oscillations and Their Relationship, ASSL, Dordrecht, 241, 1997) and Gizon and Birch (Astrophys. J. 571, 966, 2002). We investigated the relationships among these three travel-time definitions, their sensitivities to fitting parameters, and estimated the random errors that they produce.

Couvidat, S.; Zhao, J.; Birch, A. C.; Kosovichev, A. G.; Duvall, Thomas L., Jr.; Parchevsky, K.; Scherrer, P. H.

2010-01-01

266

Non-intrusive telemetry applications in the oilsands: from visible light and x-ray video to acoustic imaging and spectroscopy  

NASA Astrophysics Data System (ADS)

While the production, transport and refining of oils from the oilsands of Alberta, and comparable resources elsewhere is performed at industrial scales, numerous technical and technological challenges and opportunities persist due to the ill defined nature of the resource. For example, bitumen and heavy oil comprise multiple bulk phases, self-organizing constituents at the microscale (liquid crystals) and the nano scale. There are no quantitative measures available at the molecular level. Non-intrusive telemetry is providing promising paths toward solutions, be they enabling technologies targeting process design, development or optimization, or more prosaic process control or process monitoring applications. Operation examples include automated large object and poor quality ore during mining, and monitoring the thickness and location of oil water interfacial zones within separation vessels. These applications involve real-time video image processing. X-ray transmission video imaging is used to enumerate organic phases present within a vessel, and to detect individual phase volumes, densities and elemental compositions. This is an enabling technology that provides phase equilibrium and phase composition data for production and refining process development, and fluid property myth debunking. A high-resolution two-dimensional acoustic mapping technique now at the proof of concept stage is expected to provide simultaneous fluid flow and fluid composition data within porous inorganic media. Again this is an enabling technology targeting visualization of diverse oil production process fundamentals at the pore scale. Far infrared spectroscopy coupled with detailed quantum mechanical calculations, may provide characteristic molecular motifs and intermolecular association data required for fluid characterization and process modeling. X-ray scattering (SAXS/WAXS/USAXS) provides characteristic supramolecular structure information that impacts fluid rheology and process fouling. The intent of this contribution is to present some of the challenges and to provide an introduction grounded in current work on non-intrusive telemetry applications - from a mine or reservoir to a refinery!

Shaw, John M.

2013-06-01

267

Tavorite-FeSO4F as a potential cathode material for Mg ion batteries: a first principles calculation.  

PubMed

The electrochemical and Mg ion diffusion properties of tavorite-Mg0.5FeSO4F were studied by using first principles calculations. A discharge voltage of about 2.52 V versus Mg/Mg(2+) corresponding to the redox couples of Fe(3+)/Fe(2+) was predicted for tavorite-Mg0.5FeSO4F, and the experimental diffusion coefficient for the Mg-vacancy in Mg0.5-xFeSO4F is expected to be of the same order of magnitude as that of the Li-vacancy in Li1-xFeSO4F. PMID:25265969

Wu, Jiandong; Gao, Guohua; Wu, Guangming; Liu, Bo; Yang, Huiyu; Zhou, Xiaowei; Wang, Jichao

2014-10-01

268

Acoustic Streaming  

NASA Astrophysics Data System (ADS)

In this paper we discuss two types of acoustic streaming, to which Lighthill (1978a,b, 1997) has made significant contributions, namely the ``quartz wind'' and Rayleigh streaming. Both are associated with flows that are dominated by their fluctuating components, and owe their origin to the action of Reynolds stresses. In the former, these stresses arise within the main body of the fluid when an ultrasonic beam propagates into it; in the latter they act in the Stokes shear-wave layer that forms at a solid boundary in a fluctuating flow. In spite of its acoustic origins, we show that streaming of the Rayleigh type is a phenomenon that occurs more widely than those origins suggest.

Riley, N.

269

Medical Acoustics  

NASA Astrophysics Data System (ADS)

Medical acoustics can be subdivided into diagnostics and therapy. Diagnostics are further separated into auditory and ultrasonic methods, and both employ low amplitudes. Therapy (excluding medical advice) uses ultrasound for heating, cooking, permeablizing, activating and fracturing tissues and structures within the body, usually at much higher amplitudes than in diagnostics. Because ultrasound is a wave, linear wave physics are generally applicable, but recently nonlinear effects have become more important, even in low-intensity diagnostic applications.

Beach, Kirk; Dunmire, Barbrina

270

Contribution of Eu 4f states to the magnetic anisotropy of EuO  

SciTech Connect

Anisotropic x-ray magnetic linear dichroism (AXMLD) provides a novel element-, site-, shell-, and symmetry-selective techniques to study the magnetic anisotropy induced by a crystalline electric field. The weak Eu2+ M4,5 AXMLD observed in EuO(001) indicates that the Eu 4f states are not rotationally invariant and hence contribute weakly to the magnetic anisotropy of EuO. The results are contrasted with those obtained for 3d transition metal oxides.

Arenholz, E.; Schmehl, A.; Schlom, D.G.; van der Laan, G.

2008-09-11

271

XeCl laser pumped iodine laser using tC4F9I  

Microsoft Academic Search

An iodine photodissociation laser using t-C4F9I as the active material was pumped by an XeCl laser. An iodine laser output energy of 3 mJ with pulse duration of 25 ns was obtained when the pumping pulse energy was 80 mJ, the iodide pressure was 70 torr, and the reflectance of the output mirror was 85 percent. The high pumping efficiency

In Heon Hwang; Kwang S. Han

1989-01-01

272

XeCl laser pumped iodine laser using tC4F9I  

Microsoft Academic Search

An iodine photodissociation laser using t-C4F9I as the active material was pumped by a XeCl laser. An iodine laser output energy of 3 mJ with pulse duration of 25 ns was obtained when the pumping pulse energy was 80 mJ, the iodine pressure was 70 torr, and the reflectance of the output mirror was 85 percent. The high pumping efficiency

In Heon Hwang; Kwang S. Han; Ja H. Lee

1989-01-01

273

A 3d-4f heterometallic 3D POMOF based on lacunary Dawson polyoxometalates.  

PubMed

A novel compound, Na2[Ce4(H2O)22(dpdo)5](Mn2HP2W15O56)2·8H2O (1) (dpdo = 4,4'-bipyridine-N,N'-dioxide) with 3d-4f heterometallic 3D POMOF that can be described as a self-penetrating (4,4,6)-connected net topology, has been isolated via a stepwise method, and its magnetic and electrocatalytic properties have been investigated. PMID:24061561

Yu, Tingting; Ma, Huiyuan; Zhang, Chunjing; Pang, Haijun; Li, Shaobin; Liu, Heng

2013-12-14

274

Synthesis and Characterization of La3NbSe2O4F2  

Microsoft Academic Search

Crystals of the unusual oxyfluoroselenide La3NbSe2O4F2 were obtained during the exploration of the quaternary La\\/Nb\\/Cu\\/Se system. Oxygen was extracted from the silica tube, while fluorine was present as a minor impurity in the La powder. The compound crystallizes in space group D162h-Pnma of the orthorhombic system with four formula units in a cell with dimensions: a = 11.290(4), b =

Theodore D. Brennan; Michael F. Mansuetto; James A. Ibers

1993-01-01

275

Acoustic Tooth Cleaner  

NASA Technical Reports Server (NTRS)

Acoustically-energized water jet aids in plaque breakdown. Acoustic Wand includes acoustic transducer 1/4 wave plate, and tapered cone. Together elements energize solution of water containing mild abrasive injected into mouth to help prevent calculous buildup.

Heyman, J. S.

1984-01-01

276

Symptoms of Acoustic Neuroma  

MedlinePLUS

... Neuroma Legacy Society Search ANAUSA.org Symptoms of Acoustic Neuroma Early symptoms are easily overlooked, thus making diagnosis ... Resources Patient Survey Links Additional Resources © 2014 Acoustic Neuroma Association Acoustic Neuroma Association • 600 Peachtree Parkway • Suite 108 • Cumming, ...

277

Pb 4f photoelectron spectroscopy on mass-selected anionic lead clusters at FLASH  

NASA Astrophysics Data System (ADS)

4f core level photoelectron spectroscopy has been performed on negatively charged lead clusters, in the size range of 10-90 atoms. We deploy 4.7 nm radiation from the free-electron laser FLASH, yielding sufficiently high photon flux to investigate mass-selected systems in a beam. A new photoelectron detection system based on a hemispherical spectrometer and a time-resolving delayline detector makes it possible to assign electron signals to each micro-pulse of FLASH. The resulting 4f binding energies show good agreement with the metallic sphere model, giving evidence for a fast screening of the 4f core holes. By comparing the present work with previous 5d and valence region data, the paper presents a comprehensive overview of the energetics of lead clusters, from atoms to bulk. Special care is taken to discuss the differences of the valence- and core-level anion cluster photoionizations. Whereas in the valence case the escaping photoelectron interacts with a neutral system near its ground state, core-level ionization leads to transiently highly excited neutral clusters. Thus, the photoelectron signal might carry information on the relaxation dynamics.

Bahn, J.; Oelßner, P.; Köther, M.; Braun, C.; Senz, V.; Palutke, S.; Martins, M.; Rühl, E.; Ganteför, G.; Möller, T.; von Issendorff, B.; Bauer, D.; Tiggesbäumker, J.; Meiwes-Broer, K.-H.

2012-07-01

278

Ligand field effects on the multiplet structure of the U4f XPS of UO2  

SciTech Connect

Ab initio, fully relativistic four component theory was used to determine atomic and interatomic many-body effects for the 4f X-ray photoelectron spectrum of an embedded UO8-12 cluster representing UO2. Many-body effects were included through the use of configuration interaction wavefunctions that allow the mixing of XPS allowed and XPS forbidden configurations. Charge transfer configurations were not included. This work extends our earlier studies on simulations of the U 4f XPS for the free U4+ cation. While the main XPS features are similar in both cases, ligand field effects changed the multiplet structure in important ways that better simulated experimental data for UO2. Neither initial nor final state covalency significantly reduced the 4f-5f exchange integrals, and the differences between the atom and cluster model was due to ligand field splitting of the 5f band and increased distributions of intensity from XPS allowed to XPS forbidden peaks. The prominent 7 eV satellites associated with UO2 were absent in the simulations, and provides further evidence that these satellites are due to charge transfer and not other interatomic effects.

Ilton, Eugene S.; Bagus, Paul S.

2008-03-01

279

The acoustics of performance spaces (theatres and stadiums): a case study  

E-print Network

The acoustics of performance spaces (theatres and stadiums): a case study M. Boecka , M. Navvabb Eudossiana, 18, 00184 Rome, Italy gilles.rhone@pm-instrumentation.com Proceedings of the Acoustics 2012 to acquire the acoustic signature of rooms and buildings, superimposing acoustic images on 3D models

Boyer, Edmond

280

Hypervascular acoustic neuroma.  

PubMed

The authors present a patient with a large acoustic neuroma that exhibited an unusual vascular architecture. Magnetic resonance imaging demonstrated multiple flow voids in and around the mass. At surgery, intra- and extratumoral vascularity was arterialized due to luxurious shunting. Two attempts at removal produced severe engorgement and pulsatility of the surrounding brain, dramatically narrowing the operative exposure. Piecemeal resection of the tumor seemed to redistribute blood flow resulting in engorgement of the surrounding brain, analogous to perfusion breakthrough following AVM resection. Treatment strategies similar to those used for AVM resection may be indicated when encountering a hypervascular tumor. PMID:9864742

LeMay, D R; Sun, J K; Fishback, D; Locke, G E; Giannotta, S L

1998-12-01

281

Physica Scripta. Vol. 71, 502506, 2005 Determination of the Li I 4d4f Energy Separation Using Active  

E-print Network

Physica Scripta. Vol. 71, 502­506, 2005 Determination of the Li I 4d­4f Energy Separation Using Active Spectroscopy K. Tsigutkin*,1 , E. Stambulchik1 , Y. Maron1 and A. Tauschwitz2 1 Faculty of Physics knowledge of the Lii 4d­4f energy separation is essential for the determination of electric fields

282

A density functional theory study of 3d-4f exchange interactions in Cr-Nd codoped GaN  

NASA Astrophysics Data System (ADS)

The density functional theory based calculations of Cr, Nd and Cr/Nd co-doped wurtzite GaN generated using GGA and TB-mBJ exchange correlation functionals are being reported. All the structures were geometrically optimized and fully relaxed. The dopants introduced new energy levels in the forbidden energy gap, whose hybridization and interaction are discussed in detail to explain electronic and ferromagnetic properties of the materials. The 3d-3d interaction seems to be responsible for double exchange interaction in Cr:GaN whereas spin polarization caused by 4f-5d-CB interaction causes ferromagnetism in Nd:GaN. A model is proposed to explain the ferromagnetic ordering and 3d-4f exchange interactions in new codoped system Cr/Nd:GaN according to which 4f-5d-CB-3d interaction via 4f-5d, 4f-2p and 2p-3d coupling plays role.

Majid, Abdul; Dar, Amna

2014-11-01

283

Normal values of liver shear wave velocity in healthy children assessed by acoustic radiation force impulse imaging using a convex probe and a linear probe.  

PubMed

Acoustic radiation force impulse (ARFI) is an image-guided ultrasound elastography method that allows quantification of liver stiffness by measurement of shear wave velocity. One purpose of the work described in this article was to determine the normal liver stiffness values of healthy children using ARFI with two different probes, 4 C1 and 9 L4. Another purpose was to evaluate the effects of site of measurement, age, gender and body mass index on liver stiffness values. This prospective study included 60 healthy children (newborn to 14 y) divided into four age groups. One thousand two hundred ARFI measurements were performed, that is, 20 measurements per patient (5 measurements in each lobe, with each probe). Means, standard deviations (SD) and confidence intervals for velocity were calculated for each hepatic lobe and each probe in each age group and for the whole group. Mean shear wave velocity measured in the right lobe was 1.19 ± 0.04 m/s (SD = 0.13) with the 4 C1 transducer and 1.15 ± 0.04 m/s (SD = 0.15) with the 9 L4 transducer. Age had a small effect on shear wave measurements. Body mass index and sex had no significant effects on ARFI values, whereas site of measurement had a significant effect, with lower ARFI values in the right hepatic lobe. ARFI is a non-invasive technique that is feasible to perform in children with both the 4 C1 and 9 L4 probes. The aforementioned velocity values obtained in the right lobe may be used as reference values for normal liver stiffness in children. PMID:24361222

Fontanilla, Teresa; Cañas, Teresa; Macia, Araceli; Alfageme, Marta; Gutierrez Junquera, Carolina; Malalana, Ana; Luz Cilleruelo, Maria; Roman, Enriqueta; Miralles, Maria

2014-03-01

284

Acoustic radiation force impulse imaging with Virtual Touch(TM) tissue quantification: mean shear wave velocity of malignant and benign breast masses  

PubMed Central

Acoustic radiation force impulse imaging (ARFI) with Virtual Touch™ tissue quantification (VTTQ) enables the determination of shear wave velocity (SWV) in meters per second (m/s). The aim of our study was to describe the mean SWV in normal breast tissue and various breast masses. We performed measurements of SWV with ARFI VTTQ in 145 breast masses (57 malignant, 88 benign) and in the adjacent breast parenchyma and adipose tissue. The mean SWV as well as the rate of successful measurements were analyzed. The difference between adipose tissue and parenchyma was statistically significant (3.05 versus 3.65 m/s) (P < 0.001). Focusing on breast masses, numerous measurements exceeded the upper limit of possible measurement (?9.10 m/s, indicated as “X.XX m/s”). Nevertheless, the difference between the malignant and benign masses was statistically significant (8.38 ± 1.99 m/s versus 5.39 ± 2.95 m/s) (P < 0.001). The best diagnostic accuracy (75.9%) was achieved when the cutoff point for malignancy was set to 9.10 m/s in ARFI VTTQ. This implies that the SWV was regarded as suspicious when the upper limit of possible measurement was exceeded and the machine returned the value X.XX m/s. In conclusion, ARFI VTTQ is a feasible method for measurement of SWV in a region of interest. Furthermore, we propose the event of a highly elevated SWV as a significant criterion for malignancy. However, the method is technically not yet fully developed, and the problem of unsuccessful measurements must still be solved. PMID:24109199

Wojcinski, Sebastian; Brandhorst, Kathrin; Sadigh, Gelareh; Hillemanns, Peter; Degenhardt, Friedrich

2013-01-01

285

Imaging Transverse Isotropic Properties of Muscle by Monitoring Acoustic Radiation Force Induced Shear Waves using a 2D Matrix Ultrasound Array  

PubMed Central

A 2D matrix ultrasound array is used to monitor acoustic radiation force impulse (ARFI) induced shear wave propagation in 3D in excised canine muscle. From a single acquisition, both the shear wave phase and group velocity can be calculated to estimate the shear wave speed (SWS) along and across the fibers, as well as the fiber orientation in 3D. The true fiber orientation found using the 3D Radon Transform on B-mode volumes of the muscle was used to verify the fiber direction estimated from shear wave data. For the simplified imaging case when the ARFI push can be oriented perpendicular to the fibers, the error in estimating the fiber orientation using phase and group velocity measurements was 3.5 ±2.6° and 3.4 ±1.4° (mean ± standard deviation), respectively, over six acquisitions in different muscle samples. For the more general case when the push is oblique to the fibers, the angle between the push and the fibers is found using the dominant orientation of the shear wave displacement magnitude. In 30 acquisitions on six different muscle samples with oblique push angles up to 40°, the error in the estimated fiber orientation using phase and group velocity measurements was 5.4±2.9° and 5.3±3.2°, respectively, after estimating and accounting for the additional unknown push angle. Either the phase or group velocity measurements can be used to estimate fiber orientation and SWS along and across the fibers. Although it is possible to perform these measurements when the push is not perpendicular to the fibers, highly oblique push angles induce lower shear wave amplitudes which can cause inaccurate SWS measurements. PMID:23686942

Wang, Michael; Byram, Brett; Palmeri, Mark; Rouze, Ned; Nightingale, Kathryn

2013-01-01

286

The apolipoprotein A-I mimetic peptide 4F prevents defects in vascular function in endotoxemic rats.  

PubMed

High density lipoprotein (HDL) and apolipoprotein A-I (apoA-I) reduce inflammatory responses to lipopolysaccharide (LPS). We tested the hypothesis that the apoA-I mimetic peptide 4F prevents LPS-induced defects in blood pressure and vascular reactivity. Systolic blood pressure (SBP) was measured in rats at baseline and 6 h after injection of LPS (10 mg/kg) or saline vehicle. Subgroups of LPS-treated rats also received 4F (10 mg/kg) or scrambled 4F (Sc-4F). LPS administration reduced SBP by 35% compared with baseline. 4F attenuated the reduction in SBP in LPS-treated rats (17% reduction), while Sc-4F was without effect. Ex vivo studies showed a reduced contractile response to phenylephrine (PE) in aortae of LPS-treated rats (ED(50) = 459 +/- 83 nM) compared with controls (ED(50) = 57 +/- 6 nM). This was associated with nitric oxide synthase 2 (NOS2) upregulation. 4F administration improved vascular contractility (ED(50) = 60 +/- 9 nM), reduced aortic NOS2 protein, normalized plasma levels of NO metabolites, and reduced mortality in LPS-treated rats. These changes were associated with a reduction in plasma endotoxin activity. In vivo administration of (14)C-4F and Bodipy-LPS resulted in their colocalization and retention in the HDL fraction. It is proposed that 4F promotes the localization of LPS to the HDL fraction, resulting in endotoxin neutralization. 4F may thus prevent LPS-induced hemodynamic changes associated with NOS2 induction. PMID:20495214

Dai, Lijun; Datta, Geeta; Zhang, Zhenghao; Gupta, Himanshu; Patel, Rakesh; Honavar, Jaideep; Modi, Sarika; Wyss, J Michael; Palgunachari, Mayakonda; Anantharamaiah, G M; White, C Roger

2010-09-01

287

Performing acoustic, vibro-acoustic and aero-acoustic computations using MUMPS  

E-print Network

Performing acoustic, vibro-acoustic and aero-acoustic computations using MUMPS Eveline Rosseel Free indefinite unsymmetric systems, that arise in acoustic, vibro-acoustic and aero-acoustic simulations on the vibro- and aero-acoustic test cases. These problems are typically less sparse than pure acoustic ones

Uçar, Bora

288

Lens design for acoustic microscopy.  

PubMed

Design criteria for acoustic microscope lenses are examined with respect to their intended application. Aside from buffer rod material and F-number, the factors influencing the lens design are the critical angle for surface wave excitation, lens illumination, and leak rate of the surface wave on the sample. It is found that the design criteria are different for surface and subsurface examination and that for different applications and materials, different lenses are required for optimum imaging performance. A formalism for evaluating the performance of an acoustic microscope by considering its response in the time domain, both theoretically and experimentally, is presented. PMID:18290175

Chou, C H; Khuri-Yakub, B T; Kino, G S

1988-01-01

289

Acoustic transducer  

DOEpatents

An acoustic transducer comprising a one-piece hollow mandrel into the outer surface of which is formed a recess with sides perpendicular to the central axis of the mandrel and separated by a first distance and with a bottom parallel to the central axis and within which recess are a plurality of washer-shaped discs of a piezoelectric material and at least one disc of a temperature-compensating material with the discs being captured between the sides of the recess in a pre-stressed interference fit, typically at 2000 psi of compressive stress. The transducer also includes a power supply and means to connect to a measurement device. The transducer is intended to be used for telemetry between a measurement device located downhole in an oil or gas well and the surface. The transducer is of an construction that is stronger with fewer joints that could leak fluids into the recess holding the piezoelectric elements than is found in previous acoustic transducers.

Drumheller, Douglas S. (Cedar Crest, NM)

1997-01-01

290

Acoustic transducer  

DOEpatents

An acoustic transducer is described comprising a one-piece hollow mandrel into the outer surface of which is formed a recess with sides perpendicular to the central axis of the mandrel and separated by a first distance and with a bottom parallel to the central axis and within which recess are a plurality of washer-shaped discs of a piezoelectric material and at least one disc of a temperature-compensating material with the discs being captured between the sides of the recess in a pre-stressed interference fit, typically at 2,000 psi of compressive stress. The transducer also includes a power supply and means to connect to a measurement device. The transducer is intended to be used for telemetry between a measurement device located downhole in an oil or gas well and the surface. The transducer is of an construction that is stronger with fewer joints that could leak fluids into the recess holding the piezoelectric elements than is found in previous acoustic transducers. 4 figs.

Drumheller, D.S.

1997-12-30

291

Poly(A)-binding protein increases the binding affinity and kinetic rates of interaction of viral protein linked to genome with translation initiation factors eIFiso4F and eIFiso4F·4B complex.  

PubMed

VPg of turnip mosaic virus (TuMV) was previously shown to interact with translation initiation factor eIFiso4F and play an important role in mRNA translation [Khan, M. A., et al. (2008) J. Biol. Chem.283, 1340-1349]. VPg competed with cap analogue for eIFiso4F binding and competitively inhibited cap-dependent translation and enhanced cap-independent translation to give viral RNA a significant competitive advantage. To gain further insight into the cap-independent process of initiation of protein synthesis, we examined the effect of PABP and/or eIF4B on the equilibrium and kinetics of binding of VPg to eIFiso4F. Equilibrium data showed the addition of PABP and/or eIF4B to eIFiso4F increased the binding affinity for VPg (K(d) = 24.3 ± 1.6 nM) as compared to that with eIFiso4F alone (K(d) = 81.3 ± 0.2.4 nM). Thermodynamic parameters showed that binding of VPg to eIFiso4F was enthalpy-driven and entropy-favorable with the addition of PABP and/or eIF4B. PABP and eIF4B decreased the entropic contribution by 67% for binding of VPg to eIFiso4F. The decrease in entropy involved in the formation of the eIFiso4F·4B·PABP-VPg complex suggested weakened hydrophobic interactions for complex formation and an overall conformational change. The kinetic studies of eIFiso4F with VPg in the presence of PABP and eIF4B show 3-fold faster association (k(2) = 182 ± 9.0 s(-1)) compared to that with eIFiso4F alone (k(2) = 69.0 ± 1.5 s(-1)) . The dissociation rate was 3-fold slower (k(-2) = 6.5 ± 0.43 s(-1)) for eIFiso4F with VPg in the presence of PABP and eIF4B (k(-2) = 19.0 ± 0.9 s(-1)). The addition of PABP and eIF4B decreased the activation energy of eIFiso4F with VPg from 81.0 ± 3.0 to 44.0 ± 2.4 kJ/mol. This suggests that the presence of both proteins leads to a rapid, stable complex, which serves to sequester initiation factors. PMID:22299678

Khan, Mateen A; Goss, Dixie J

2012-02-21

292

XeCl laser pumped iodine laser using t-C4F9I  

NASA Technical Reports Server (NTRS)

An iodine photodissociation laser using t-C4F9I as the active material was pumped by an XeCl laser. An iodine laser output energy of 3 mJ with pulse duration of 25 ns was obtained when the pumping pulse energy was 80 mJ, the iodide pressure was 70 torr, and the reflectance of the output mirror was 85 percent. The high pumping efficiency and low threshold pump power achieved in this experiment are attributable to the high absorption cross section at the pump laser wavelength (308 nm) of the iodide used.

Hwang, In Heon; Han, Kwang S.

1989-01-01

293

XeCl laser pumped iodine laser using t-C4F9I  

NASA Technical Reports Server (NTRS)

An iodine photodissociation laser using t-C4F9I as the active material was pumped by a XeCl laser. An iodine laser output energy of 3 mJ with pulse duration of 25 ns was obtained when the pumping pulse energy was 80 mJ, the iodine pressure was 70 torr, and the reflectance of the output mirror was 85 percent. The high pumping efficiency and low threshold pump power achieved in this experiment are attributable to the high absorption cross section at the pump laser wavelength (308 nm) of the iodide used.

Hwang, In Heon; Han, Kwang S.; Lee, Ja H.

1989-01-01

294

The importance of acoustic cavitation in the sonocrystallisation of ice-high speed observations of a single acoustic bubble  

Microsoft Academic Search

The importance of cavitation bubbles in the nucleation of ice crystals in pure water is examined using a single bubble acoustic levitation and high speed imaging system. The dynamic images have shown that neither air bubbles (manually added to the solution), nor an acoustic pressure wave alone (in the absence of cavitation) is sufficient to cause the nucleation of ice

R. Chow; R. Mettin; B. Lindinger; T. Kurz; W. Lauterborn

2003-01-01

295

Acoustic transducer  

DOEpatents

An active acoustic transducer tool for use down-hole applications. The tool includes a single cylindrical mandrel including a shoulder defining the boundary of a narrowed portion over which is placed a sandwich-style piezoelectric tranducer assembly. The piezoelectric transducer assembly is prestressed by being placed in a thermal interference fit between the shoulder of the mandrel and the base of an anvil which is likewise positioned over the narrower portion of the mandrel. In the preferred embodiment, assembly of the tool is accomplished using a hydraulic jack to stretch the mandrel prior to emplacement of the cylindrical sandwich-style piezoelectric transducer assembly and anvil. After those elements are positioned and secured, the stretched mandrel is allowed to return substantially to its original (pre-stretch) dimensions with the result that the piezoelectric transducer elements are compressed between the anvil and the shoulder of the mandrel.

Drumheller, Douglas S. (Cedar Crest, NM)

2000-01-01

296

Acoustic telemetry.  

SciTech Connect

Broadcasting messages through the earth is a daunting task. Indeed, broadcasting a normal telephone conversion through the earth by wireless means is impossible with todays technology. Most of us don't care, but some do. Industries that drill into the earth need wireless communication to broadcast navigation parameters. This allows them to steer their drill bits. They also need information about the natural formation that they are drilling. Measurements of parameters such as pressure, temperature, and gamma radiation levels can tell them if they have found a valuable resource such as a geothermal reservoir or a stratum bearing natural gas. Wireless communication methods are available to the drilling industry. Information is broadcast via either pressure waves in the drilling fluid or electromagnetic waves in the earth and well tubing. Data transmission can only travel one way at rates around a few baud. Given that normal Internet telephone modems operate near 20,000 baud, these data rates are truly very slow. Moreover, communication is often interrupted or permanently blocked by drilling conditions or natural formation properties. Here we describe a tool that communicates with stress waves traveling through the steel drill pipe and production tubing in the well. It's based on an old idea called Acoustic Telemetry. But what we present here is more than an idea. This tool exists, it's drilled several wells, and it works. Currently, it's the first and only acoustic telemetry tool that can withstand the drilling environment. It broadcasts one way over a limited range at much faster rates than existing methods, but we also know how build a system that can communicate both up and down wells of indefinite length.

Drumheller, Douglas Schaeffer; Kuszmaul, Scott S.

2003-08-01

297

Dual-modality section imaging system with optical ultrasound detection for photoacoustic and ultrasound imaging  

NASA Astrophysics Data System (ADS)

We propose the further development of the optical detection setup towards photoacoustic (PA) and ultrasound (US) dual-modality section imaging. Both imaging modalities use optical generation and detection of ultrasound waves. A onesided chrome coated concave cylindrical optical lens is used as target to induce acoustic signals for US imaging and as acoustic mirror that forms acoustic images. By probing the temporal evolution of the acoustic images with an optical beam perpendicular to the acoustic axis and simultaneously rotating the object, data for reconstruction of PA and US slice images are acquired. All acoustic signals are excited optically via the thermoelastic effect using laser pulses coming from the same laser system.

Nuster, Robert; Wurzinger, Gerhild; Gratt, Sibylle; Paltauf, Guenther

2013-03-01

298

Treatment of 4f states of the rare earths: The case study of TbN  

NASA Astrophysics Data System (ADS)

The lattice constant, bulk modulus, and shear constant of TbN are calculated by means of density functional theory (DFT) in the local density approximation (LDA) and generalized gradient approximation (GGA), with 4f states treated as valence electrons or core electrons. In addition, local Coulomb repulsions U are treated both statically as in the LDA+U approach and dynamically as in the dynamical mean-field theory in the Hubbard-I approximation. It is shown that all methods, except DFT-LDA with 4f electrons treated as either valence states, produce lattice constants and bulk moduli in good agreement with experiment. In the LDA+U approach multiple minima are found, and we focus on the competition between a state with cubic symmetry and a state obtained from atomic Hund's rules. We find the state with cubic symmetry to be 0.59 eV lower in energy than the Hund's rules state, while the opposite was obtained in previous literature. The shear constant is shown to be rather sensitive to the theoretical method used, and the Hund's rules state obtained in LDA+U is found to be unstable towards tetragonal shear. As to the magnetism, we find that the calculation based on the Hubbard-I approximation reproduces observations with the best accuracy. Finally, the spectral properties of TbN are discussed, together with the general applicability of the different methods in describing rare-earth elements and compounds.

Peters, L.; Di Marco, I.; Thunström, P.; Katsnelson, M. I.; Kirilyuk, A.; Eriksson, O.

2014-05-01

299

A protein that replaces the entire cellular eIF4F complex  

PubMed Central

The eIF4F cap-binding complex mediates the initiation of cellular mRNA translation. eIF4F is composed of eIF4E, which binds to the mRNA cap, eIF4G, which indirectly links the mRNA cap with the 43S pre-initiation complex, and eIF4A, which is a helicase necessary for initiation. Viral nucleocapsid proteins (N) function in both genome replication and RNA encapsidation. Surprisingly, we find that hantavirus N has multiple intrinsic activities that mimic and substitute for each of the three peptides of the cap-binding complex thereby enhancing the translation of viral mRNA. N binds with high affinity to the mRNA cap replacing eIF4E. N binds directly to the 43S pre-initiation complex facilitating loading of ribosomes onto capped mRNA functionally replacing eIF4G. Finally, N obviates the requirement for the helicase, eIF4A. The expression of a multifaceted viral protein that functionally supplants the cellular cap-binding complex is a unique strategy for viral mRNA translation initiation. The ability of N to directly mediate translation initiation would ensure the efficient translation of viral mRNA. PMID:18971945

Mir, Mohammad A; Panganiban, Antonito T

2008-01-01

300

Lattice dynamics and elastic properties of the 4f electron system: CeN  

NASA Astrophysics Data System (ADS)

The electronic structure, structural stability, and lattice dynamics of cerium mononitride are investigated using ab initio density-functional methods involving an effective potential derived from the generalized gradient approximation and without special treatment for the 4f states. The 4f states are hence allowed to hop from site to site, without an on-site Hubbard U, and contribute to the bonding, in a picture often referred to as itinerant. It is argued that this picture is appropriate for CeN at low temperatures, while the anomalous thermal expansion observed at elevated temperatures indicates entropy-driven localization of the Ce f electrons, similar to the behavior of elemental cerium. The elastic constants are predicted from the total energy variation of strained crystals and are found to be large, typical for nitrides. The phonon dispersions are calculated showing no soft modes, and the Grüneisen parameter behaves smoothly. The electronic structure is also calculated using the quasiparticle self-consistent GW approximation (where G denotes the Green's function and W denotes the screened interaction). The Fermi surface of CeN is dominated by large egg-shaped electron sheets centered on the X points, which stem from the p-f mixing around the X point. In contrast, assuming localized f electrons leads to a semimetallic picture with small band overlaps around X.

Kanchana, V.; Vaitheeswaran, G.; Zhang, Xinxin; Ma, Yanming; Svane, A.; Eriksson, O.

2011-11-01

301

Acoustic impedance inversion of the Lower Permian carbonate buildups in the Permian Basin, Texas  

E-print Network

of these complex carbonate structures. In order to obtain a better characterization and imaging of the carbonate buildups, an acoustic impedance inversion is proposed here. The resolution of the acoustic impedance is the same as the input seismic data, which...

Pablo, Buenafama Aleman

2004-11-15

302

Downregulation of transcription factor E4F1 in hepatocarcinoma cells: HBV-dependent effects on autophagy, proliferation and metabolism.  

PubMed

The multifunctional E4F1 protein is a cellular target of the E1A adenoviral oncoprotein. Interaction between E4F1 and the hepatitis B virus (HBV) protein HBx has been demonstrated in vitro. In this study, RNA interference has been used to downregulate E4F1 in the hepatocellular carcinoma (HCC) cell line HepG2 (HBV negative) and its derivative, HBV expressing HepG2/2.2.15. Reduction of E4F1 levels induced hepatocyte vacuolation (formation of large cytoplasmic vesicles), increased autophagy and caused mitochondrial defects and metabolism changes in HepG2/2.2.15, but not in HepG2. Moreover, downregulation of E4F1 reduced DNA synthesis with partial cell cycle arrest in G1 in both cell types and this effect was more marked in HepG2/2.2.15 than in HepG2. These effects were partially prevented by RNA interference directed to either HBx or to p53. Coprecipitation and western blot experiments detected complexes between E4F1 and HBx in several HCC cell lines. Although a review of mutation and gene expression public databases did not support that E4F1 is specifically altered in liver cancer, our results suggest that E4F1 may neutralize the capacity of HBx to activate a p53-dependent, metabolic and growth arrest phenotype in liver cells, thus possibly contributing to the viability and proliferation of HBV-infected cells. PMID:24163401

Dai, Yayun; Cros, Marie-Pierre; Pontoizeau, Clément; Elena-Hermann, Bénédicte; Bonn, Günther K; Hainaut, Pierre

2014-03-01

303

Design and Experimental Applications of Acoustic Metamaterials  

NASA Astrophysics Data System (ADS)

Acoustic metamaterials are engineered materials that were extensively investigated over the last years mainly because they promise properties otherwise hard or impossible to find in nature. Consequently, they open the door for improved or completely new applications (e.g. acoustic superlens that can exceed the diffraction limit in imaging or acoustic absorbing panels with higher transmission loss and smaller thickness than regular absorbers). Our objective is to surpass the limited frequency operating range imposed by the resonant mechanism that s1ome of these materials have. In addition, we want acoustic metamaterials that could be experimentally demonstrated and used to build devices with overall performances better than the previous ones reported in the literature. Here, we start by focusing on the need of engineered metamaterials in general and acoustic metamaterials in particular. Also, the similarities between electromagnetic metamaterials and acoustic metamaterials and possible ways to realize broadband acoustic metamaterials are briefly discussed. Then, we present the experimental realization and characterization of a two-dimensional (2D) broadband acoustic metamaterial with strongly anisotropic effective mass density. We use this metamaterial to realize a 2D broadband gradient index acoustic lens in air. Furthermore, we optimize the lens design by improving each unit cell's performance and we also realize a 2D acoustic ground cloak in air. In addition, we explore the performance of some novel applications (a 2D acoustic black hole and a three-dimensional acoustic cloak) using the currently available acoustic metamaterials. In order to overcome the limitations of our designs, we approach the active acoustic metamaterials path, which offers a broader range for the material parameters values and a better control over them. We propose two structures which contain a sensing element (microphone) and an acoustic driver (piezoelectric membrane or speaker). The material properties are controlled by tuning the response of the unit cell to the incident wave. Several samples with interesting effective mass density and bulk modulus are presented. We conclude by suggesting few natural directions that could be followed for the future research based on the theoretical and experimental results presented in this work.

Zigoneanu, Lucian

304

MINIMUM RISK ACOUSTIC CLUSTERING FOR MULTILINGUAL ACOUSTIC MODEL COMBINATION  

E-print Network

MINIMUM RISK ACOUSTIC CLUSTERING FOR MULTILINGUAL ACOUSTIC MODEL COMBINATION Dimitra Vergyri for combining multiple acoustic models, obtained using training corpora from different languages, in order of classes. 1. INTRODUCTION Multilingual acoustic modeling is motivated by the need for speech recognizers

Byrne, William

305

The Sounds of Nanoscience: Acoustic STM Analogues  

ERIC Educational Resources Information Center

A hands-on model of scanning tunnelling microscopy (STM) is presented. It uses near-field imaging with sound and computer assisted visualization to create acoustic mappings of resonator arrangements. Due to the (partial) analogy of matter and sound waves the images closely resemble STM scans of atoms. Moreover, the method can be extended to build…

Euler, Manfred

2013-01-01

306

Acoustic-photorefractive recording of acoustical oscillations  

SciTech Connect

The process whereby acoustic waves are recorded in photorefractive piezoelectric crystals by means of the acoustophotorefractive effect is studied. Expression are obtained for the electric fields and elastic displacements of the recorded holographic lattice. The kinetics of the recording of monochromatic waves and complex acoustic signals under the action of pulsed uniform illumination is studied. It is shown that in the case when a complex acoustic signal is recorded the signal recorded with short recording times is the derivative of the input signal.

Zelenskaya, T.E.; Shandarov, S.M.

1988-01-01

307

PT-Symmetric Acoustics  

NASA Astrophysics Data System (ADS)

We introduce here the concept of acoustic parity-time (PT) symmetry and demonstrate the extraordinary scattering characteristics of the acoustic PT medium. On the basis of exact calculations, we show how an acoustic PT-symmetric medium can become unidirectionally transparent at given frequencies. Combining such a PT-symmetric medium with transformation acoustics, we design two-dimensional symmetric acoustic cloaks that are unidirectionally invisible in a prescribed direction. Our results open new possibilities for designing functional acoustic devices with directional responses.

Zhu, Xuefeng; Ramezani, Hamidreza; Shi, Chengzhi; Zhu, Jie; Zhang, Xiang

2014-07-01

308

Magnetism and superconductivity driven by identical 4f states in a heavy-fermion metal  

SciTech Connect

The apparently inimical relationship between magnetism and superconductivity has come under increasing scrutiny in a wide range of material classes, where the free energy landscape conspires to bring them in close proximity to each other. Particularly enigmatic is the case when these phases microscopically interpenetrate, though the manner in which this can be accomplished remains to be fully comprehended. Here, we present combined measurements of elastic neutron scattering, magnetotransport, and heat capacity on a prototypical heavy fermion system, in which antiferromagnetism and superconductivity are observed. Monitoring the response of these states to the presence of the other, as well as to external thermal and magnetic perturbations, points to the possibility that they emerge from different parts of the Fermi surface. Therefore, a single 4f state could be both localized and itinerant, thus accounting for the coexistence of magnetism and superconductivity.

Thompson, Joe E [Los Alamos National Laboratory; Nair, S [MAX PLANCK INST.; Stockert, O [MAX PLANCK INST.; Witte, U [INST. FUR FESTKORPERPHYSIK; Nicklas, M [MAX PLANCK INST.; Schedler, R [HELMHOLTZ - ZENTRUM; Bianchi, A [UC, IRVINE; Fisk, Z [UC, IRVINE; Wirth, S [MAX PLANCK INST.; Steglich, K [HELMHOLTZ - ZENTRUM

2009-01-01

309

Pu 4f XPS spectra analyzed in the Anderson impurity model  

SciTech Connect

X-ray photoemission spectra of the {alpha},{beta},{gamma}, and {delta} phases of Pu have been analyzed using the Gunnarsson-Schonhammer implementation of the Anderson impurity model. Changes in the relative intensities of the two spectral features representing mixed f{sup 5} and f{sup 6} final states are in reasonable agreement with the model`s predictions. The coulomb terms, U{sub ff} and U{sub fc}, are quite consistent with those derived from atomic and LDA calculations. Multiplet structure, which agrees with atomic calculations for 4f{sup 13}5f{sup 5}, strongly suggests 5f localization in the final state.

Cox, L.E.; Peek, J.M. [Los Alamos National Lab., NM (United States). Nuclear Materials Technology Div.; Allen, J.W. [Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Physics

1998-05-09

310

Structural characterization and unfolding mechanism of human 4F2hc ectodomain.  

PubMed

4F2hc (CD98hc) is a multifunctional type II membrane glycoprotein involved in several functions as amino acid transport, cell fusion, ?1-integrin-signaling and transformation. 4F2hc ectodomain has been crystallized and its three-dimensional structure determined. We have carried out a spectroscopical/structural characterization of the recombinant ectodomain in order to obtain information on its dynamic structure in solution and on its ability to form homodimers by itself in the absence of the transmembrane helix and of the potential interactions with the plasma membrane. Analytical ultracentrifugation and crosslinking experiments showed that the ectodomain is monomeric in solution. The secondary structure determined by far-UV circular dichroism (CD) spectroscopy (around 30% ?-helix and 20% ?-sheets, 12% antiparallel and 8% parallel) reveals a compact and thermally stable structure with a high melting temperature (57-59°C). Tryptophan residues are mainly buried and immobilized in the hydrophobic core of the protein as suggested by near-UV CD spectrum, the position of the Trp maximum fluorescence emission (323nm) and from the acrylamide quenching constant (2.6M(-1)). Urea unfolding equilibrium has been studied by far-UV CD and fluorescence spectroscopy to gain information on the folding/unfolding process of the ectodomain. The analyses suggest the existence of two intermediate states as reported for other TIM barrel-containing proteins rather than an independent unfolding of each domain [A, (??)(8) barrel; C, antiparallel ?(8) sandwich]. Folding seems to be directed by the initial formation of hydrophobic clusters within the first strands of the ?-barrel of domain A followed by additional hydrophobic interactions in domain C. PMID:21352957

Turnay, Javier; Fort, Joana; Olmo, Nieves; Santiago-Gómez, Angélica; Palacín, Manuel; Lizarbe, M A Antonia

2011-05-01

311

Acoustic Imaging Evaluation of Juvenile Salmonid Behavior in the Immediate Forebay of the Water Temperature Control Tower at Cougar Dam, 2010  

SciTech Connect

This report presents the results of an evaluation of juvenile Chinook salmonid (Oncorhynchus tshawytscha) behavior in the immediate forebay of the Water Temperature Control (WTC) tower at Cougar Dam in 2010. The study was conducted by the Pacific Northwest National Laboratory for the U.S. Army Corps of Engineers. The overall goal of the study was to characterize juvenile salmonid behavior and movement patterns in the immediate forebay of the WTC tower for fisheries resource managers to use to make decisions on bioengineering designs for long-term structures and/or operations to facilitate safe downstream passage for juvenile salmonids. We collected acoustic imaging (Dual-Frequency Identification Sonar; DIDSON) data from February 1, 2010 through January 31, 2011 to evaluate juvenile salmonid behavior year-round in the immediate forebay surface layer of the WTC tower (within 20 m, depth 0-5 m). From October 28, 2010 through January 31, 2011 a BlueView acoustic camera was also deployed in an attempt to determine its usefulness for future studies as well as augment the DIDSON data. For the DIDSON data, we processed a total of 35 separate 24-h periods systematically covering every other week in the 12-month study. Two different 24-hour periods were processed for the BlueView data for the feasibility study. Juvenile salmonids were present in the immediate forebay of the WTC tower throughout 2010. The juvenile salmonid abundance index was low in the spring (<200 fish per sample-day), began increasing in late April and peaked in mid-May. Fish abundance index began decreasing in early June and remained low in the summer months. Fish abundance increased again in the fall, starting in October, and peaked on November 8-9. A second peak occurred on December 22. Afterwards, abundance was low for the rest of the study (through January 2011). Average fish length for juvenile salmonids during early spring 2010 was 214 {+-} 86 mm (standard deviation). From May through early November, average fish length remained relatively consistent (132 {+-} 39 mm), after which average lengths increased to 294 {+-} 145 mm for mid-November though early December. Fish behavior analysis indicates milling in front of the intake tower was the most common behavior observed throughout the study period (>50% of total fish events). The next most common movement patterns were fish traversing along the front of the tower, east-to-west and west-to-east. The proportion of fish events seen moving into (forebay to tower) or out of (tower to forebay) the tower was generally low throughout the spring, summer, and early fall for both directions combined. From mid-December 2010 through the end of the study, the combined proportions of fish moving into and out of the tower were higher than previous months of this study. Schooling behavior was most distinct in the spring from late April through mid-June. Schooling events were present in 30 - 96% of the fish events during that period, with a peak in mid-May. Schooling events were also present in the summer, but at lower numbers. Diel distributions for schooling fish during spring, fall, and winter months indicate schooling was concentrated during daylight hours. No schooling was observed at night. Predator activity was observed during late spring, when fish abundance and schooling were highest for the year, and again in the fall months when fish events increased from a summer low. No predator activity was observed in the summer, and little activity occurred during the winter months. For the two days of BlueView data analyzed for vertical distribution in the forebay, a majority of fish (>50%) were present in the middle of the water column (10 - 20 m deep). Between 20 and 41 % of total fish abundance were found in the bottom of the water column (20 - 30 m deep). Few fish were observed in the top 10 m of the water column.

Khan, Fenton; Johnson, Gary E.; Royer, Ida M.; Phillips, Nathan RJ; Hughes, James S.; Fischer, Eric S.; Ploskey, Gene R.

2011-10-01

312

Comparative 4f-4f absorption spectral study for the interactions of Nd(III) with some amino acids: Preliminary thermodynamics and kinetic studies of interaction of Nd(III):glycine with Ca(II)  

NASA Astrophysics Data System (ADS)

Spectral analysis of Nd(III) complexes with some amino acids viz.; glycine, L-alanine, L-phenylalanine and L-aspartic acid in the presence and absence of Ca 2+ was carried out in some organic solvents; CH 3OH, CH 3CN, DMF and dioxane using comparative absorption spectra of 4f-4f transitions. The study was carried out by evaluating various energy interaction parameters like Slator-Condon ( Fk), Lande factor ( ?4f), nephelauxetic ratio ( ?), bonding parameter ( b1/2), percent-covalency ( ?) by applying partial and multiple regression analysis. The values of oscillator strength ( Pobs) and Judd-Ofelt electric dipole intensity parameter T? ( ? = 2, 4, 6) for different 4f-4f transitions have been calculated. On analysis of the variation of the various energy interaction parameters as well as the changes in the oscillator strength ( Pobs) and T? values, reveal the mode of binding with the different ligands. Kinetic studies for the complexation of Nd(III):glycine:Ca(II) have also been discussed at different temperatures in DMF medium and from it the values of activation energy ( Ea) and thermodynamic parameters like ? H°, ? S° and ? G° for the complexation are evaluated.

Moaienla, T.; Bendangsenla, N.; David Singh, Th.; Sumitra, Ch.; Rajmuhon Singh, N.; Indira Devi, M.

2012-02-01

313

Use of the 4F Roesch Inferior Mesenteric Catheter in Embolization Procedures in the Pelvis: A Review of 300 Cases  

SciTech Connect

The aim of this study is to evaluate the use of a 4F Roesch inferior mesenteric (RIM) catheter for pelvic embolization procedures. Between October 2000 and January 2006, 364 patients (357 female, 7 male; age: 23-67 years) underwent embolization of various pathologies [uterine fibroids (n = 324), pure adenomyosis of the uterus (n = 19), postpartum hemorrhage (n =1), traumatic or postoperative hemorrhage (n = 9), bleeding related to cervical cancer (n =7), AV malformation of the uterus (n = 2) and high-flow priapism (n = 2)] at a single institution. In all cases, bilateral catheterization was primarily attempted with the use of a 4F hook-shaped braided endhole catheter (Roesch-Inferior-Mesenteric, RIM-Catheter, Cordis, Miami, FL). Frequency of initial failure to catheterize the vascular territory of interest and carry out the embolization were recorded and the types of difficulty encountered were noted. Catherization of the main stem of the vessel territory of interest with the use of a unilateral femoral approach and the 4F RIM catherer was successful in 334/364 (91.8%) the embolization cases. Bilateral catheterization of the internal iliac arteries using a single common femoral artery access and the 4F RIM catheter was achieved in 322/364 (88.5%) patients. In 12/364 (3.3%) patients, a contralateral puncture was performed and the same 4F catheter was used. In 28/364 (7.7%) cases the 4F RIM catheter was exchanged for a catheter with a cobra-shaped or sidewinder configuration. The 4F RIM catheter is a simple and valuable alternative to catheters and techniques commonly employed for pelvic artery embolization.

Kroencke, Thomas J., E-mail: thomas.kroencke@charite.de; Kluner, Claudia; Hamm, Bernd [Charite Universitaetsmedizin Berlin, Department of Radiology (Germany); Gauruder-Burmester, Annett [St. Hedwig Hospital, German Pelvic Floor Centre, Department of Urogynecology (Germany)

2007-04-15

314

Regulation of the Orphan Nuclear Receptor Nr2f2 by the DFNA15 Deafness Gene Pou4f3  

PubMed Central

Hair cells are the mechanotransducing cells of the inner ear that are essential for hearing and balance. POU4F3 – a POU-domain transcription factor selectively expressed by these cells – has been shown to be essential for hair cell differentiation and survival in mice and its mutation in humans underlies late-onset progressive hearing loss (DFNA15). The downstream targets of POU4F3 are required for hair cell differentiation and survival. We aimed to identify such targets in order to elucidate the molecular pathways involved in hair cell production and maintenance. The orphan thyroid nuclear receptor Nr2f2 was identified as a POU4F3 target using a subtractive hybridization strategy and EMSA analysis showed that POU4F3 binds to two sites in the Nr2f2 5? flanking region. These sites were shown to be required for POU4F3 activation as their mutation leads to a reduction in the response of an Nr2f2 5? flanking region reporter construct to POU4F3. Immunocytochemistry was carried out in the developing and adult inner ear in order to investigate the relevance of this interaction in hearing. NR2F2 expression in the postnatal mouse organ of Corti was shown to be detectable in all sensory epithelia examined and characterised. These data demonstrate that Nr2f2 is a direct target of POU4F3 in vitro and that this regulatory relationship may be relevant to hair cell development and survival. PMID:25372459

Tornari, Chrysostomos; Towers, Emily R.; Gale, Jonathan E.; Dawson, Sally J.

2014-01-01

315

Acoustic Simulation COMP 768 Presentation  

E-print Network

Acoustic Simulation COMP 768 Presentation Lakulish Antani April 9, 2009 #12;Acoustic Simulation #12;Outline · Introduction · Numerical Acoustics · Geometric Acoustics · Statistical Acoustics · Hybrid Acoustics 4 #12;Problem Statement · Input: ­ Scene geometry ­ Source position(s) ­ Listener

North Carolina at Chapel Hill, University of

316

Acoustic Neuroma Educational Video  

MedlinePLUS Videos and Cool Tools

... Watch and Wait Radiation Microsurgery Acoustic Neuroma Decision Tree Questions for Your Physician Questions to Ask Yourself ... Watch and Wait Radiation Microsurgery Acoustic Neuroma Decision Tree Questions for Your Physician Questions to Ask Yourself ...

317

Tutorial on architectural acoustics  

NASA Astrophysics Data System (ADS)

This tutorial is intended to provide an overview of current knowledge and practice in architectural acoustics. Topics covered will include basic concepts and history, acoustics of small rooms (small rooms for speech such as classrooms and meeting rooms, music studios, small critical listening spaces such as home theatres) and the acoustics of large rooms (larger assembly halls, auditoria, and performance halls).

Shaw, Neil; Talaske, Rick; Bistafa, Sylvio

2002-11-01

318

Acoustic Heating Peter Ulmschneider  

E-print Network

Acoustic Heating Peter Ulmschneider lnstitut fiir Theoretische Astrophysik der Universitat Heidelberg Im Neuenheimer Feld 561, 6900 Heidelberg 1, Federal Republic of Germany. Abstract. Acoustic shock waves are a viable and prevalent heating mechanism both in early- and in late-type stars. Acoustic

Ulmschneider, Peter

319

Acoustic tomography. Laboratory technique Implementation.  

NASA Astrophysics Data System (ADS)

From geomechanical tests carried out on rocks it is possible to determine its physico-mechanical properties, which relate the strain and applied stress; even so, conventional tests do not allow to identify how stress is distributed and how it has affected porous media. Today, techniques like acoustic tomography widely used in medicine, geophysics and others sciences, generates images by sections of the interior of a body. Acoustic tomography allows inferring the stress state within porous media; since wave velocities are closely related to media density, if a stress is applied to a rock, it will generate grains compaction and this will be showed by an increase of wave velocity. Implementation was conducted on rock plugs under diverse stress fields, simultaneously recording P-wave velocities (Compressional) on perpendicular planes to sample vertical axis. Transmission and reception of acoustic waves through porous media were done by piezoelectric crystals (PZT) used as sensors. A transmitting crystal excited by a voltage pulse causes a mechanical vibration, which travels across media; this is known as inverse piezoelectric effect. This vibration is recorded by a receiving crystal in which the direct piezoelectric effect appears; which dictates that if a piezoelectric is disturbed mechanically, an electrical signal between its terminals will appear. This electrical signal is used to obtain the wave velocity. Nevertheless, acoustic tomography corresponds to one of those called inverse Problems that arise when from observed data the model parameters must be obtained; in this way, tomography involves iterative reconstruction techniques (ART or SIRT) which are projections of observed data and its later inversion. Obtained results are cross-sectional images of velocity within the rock. In these images it is possible to identify where stress has a greater concentration observing the color map generated; thus, a greater velocity density area corresponding to a greater stress will be colored with a higher tonality within the palette used.

Galvis, Jorge; Carvajal, Jenny

2010-05-01

320

Redshift of acoustic waves in acoustic streaming.  

PubMed

Redshift, namely, the frequency decline in the frequency spectrum of an acoustic wave in water, was observed by measuring the frequency spectrum of acoustic streaming in a standing wave field. We desire that relations of the energy epsilon and momentum mu of acoustic waves analogous to those under quantum conditions hold, that is, epsilon =n(p)h(omega), mu=n(p)h(k), where h=h/2pi (h is Planck's constant), n(p) is the phonon density, omega is the angular frequency, and k is the wave number. In this case, a redshift indicates that acoustic waves suffer energy loss or annihilation of phonons. We show that the driving force of streaming is derived from the momentum transfer of phonons and the direct conversion of energy from acoustic energy to kinetic energy of the medium. PMID:12935240

Sato, Masanori; Matsuo, Tsuyoshi; Fujii, Toshitaka

2003-07-01

321

Acoustic Imaging Evaluation of Juvenile Salmonid Behavior in the Immediate Forebay of the Water Temperature Control Tower at Cougar Dam, 2010  

SciTech Connect

This report presents the results of an evaluation of juvenile Chinook salmon (Oncorhynchus tshawytscha) behavior at Cougar Dam on the south fork of the McKenzie River in Oregon in 2010. The study was conducted by the Pacific Northwest National Laboratory for the U.S. Army Corps of Engineers (USACE). The overall goal of the study was to characterize juvenile salmonid behavior and movement patterns in the immediate forebay of the Water Temperature Control (WTC) tower of the dam for USACE and fisheries resource managers use in making decisions about bioengineering designs for long-term structures and/or operations to facilitate safe downstream passage for juvenile salmonids. We collected acoustic imaging (Dual-Frequency Identification Sonar; DIDSON) data from March 1, 2010, through January 31, 2011. Juvenile salmonids (hereafter, called 'fish') were present in the immediate forebay of the WTC tower throughout the study. Fish abundance index was low in early spring (<200 fish per sample-day), increased in late April, and peaked on May 19 (6,039 fish). A second peak was observed on June 6 (2904 fish). Fish abundance index decreased in early June and remained low in the summer months (<100 fish per sample-day). During the fall and winter, fish numbers varied with a peak on November 10 (1881 fish) and a minimum on December 7 (12 fish). A second, smaller, peak occurred on December 22 (607 fish). A univariate statistical analysis indicated fish abundance index (log10-transformed) was significantly (P<0.05) positively correlated with forebay elevation, velocity over the WTC tower intake gate weirs, and river flows into the reservoir. A subsequent multiple regression analysis resulted in a model (R2=0.70) predicting fish abundance (log-transformed index values) using two independent variables of mean forebay elevation and the log10 of the forebay elevation range. From the approximate fish length measurements made using the DIDSON imaging software, the average fish length during early spring 2010 was 214 {+-} 86 mm (standard deviation). From May through early November, the average fish length remained relatively consistent (132 {+-} 54 mm), after which average lengths increased to 295 {+-} 148 mm for mid-November though early December. From mid-December through January the average fish length decreased to 151 {+-} 76 mm. Milling in front of the WTC tower was the most common fish behavior observed throughout the study period. Traversing along the front of the tower, east-to-west and west-to-east, was the next common behavior. The percentage of fish events showing movement from the forebay to the tower or from the tower to the forebay was generally low throughout the spring, summer, and early fall (0 to 30% for both directions combined, March through early November). From mid-November 2010 through the end of the study (January 31, 2011), the combined percentages of fish moving into and out of the tower were higher (25 to 70%) than during previous months of the study. Schooling behavior was most distinct in the spring. Schooling events were present in 30 to 96% of the fish events during that period, with a peak on May 19. Schooling events were also present in the summer, but at lower numbers. With the exception of some schooling in mid-December, few to no schooling events were observed in the fall and winter months. Diel distributions for schooling fish during spring and fall months indicate schooling was concentrated during daylight hours and no schooling was observed at night. However, in December, schooling occurred at night, after midnight, and during daylight hours. Predator activity, most likely bull trout or rainbow trout according to a USACE biologist, was observed during late spring, when fish abundance index and schooling were highest for the year, and again in the fall months when fish events increased from a summer low. No predator activity was observed in the summer, and little activity occurred during the winter months.

Khan, Fenton; Johnson, Gary E.; Royer, Ida M.; Phillips, Nathan RJ; Hughes, James S.; Fischer, Eric S.; Ham, Kenneth D.; Ploskey, Gene R.

2012-04-01

322

Microstress contrast in scanning electron acoustic microscopy of ceramics  

NASA Technical Reports Server (NTRS)

A mathematical model of image contrast in scanning electron acoustic microscopy (SEAM) due to the effect of residual stresses in materials is presented. It is found that in regions near the ends of the radial cracks induced by Vickers indentation the SEAM micrographs reveal a rather large variation of the acoustic output signal.

Cantrell, John H.; Qian, Menglu

1991-01-01

323

Acoustic holography. Citations from the Engineering Index data base  

NASA Astrophysics Data System (ADS)

Worldwide research on acoustic holography is covered. Theory, uses, equipment design, and imaging techniques are presented. Most of the studies are general and not applied to a specific use of acoustic holography. However, there are citations which do discuss its use in medicine, nuclear reactors, and nondestructive testing. This updated bibliography contains 328 citations, 34 of which are new entries to the previous edition.

Reed, W. E.

1980-07-01

324

R&D studies of a RICH detector using pressurized C4F8O radiator gas and a CsI-based gaseous photon detector  

NASA Astrophysics Data System (ADS)

We report on studies of layout and performance of a new Ring Imaging Cherenkov detector using for the first time pressurized C4F8O radiator gas and a photon detector consisting of a MWPC equipped with a CsI photocathode. In particular, we present here the results of beam tests of a MWPC having an adjustable anode-cathode gap, aiming at the optimization of single photoelectron detection and Cherenkov angle resolution. This system was proposed as a Very High Momentum Particle Identification (VHMPID) upgrade for the ALICE experiment at LHC to provide charged hadron track-by-track identification in the momentum range 5-25 GeV/c.

Agócs, A. G.; Barile, F.; Barnaföldi, G. G.; Bellwied, R.; Bencédi, G.; Bencze, G.; Berényi, D.; Boldizsár, L.; Chattopadhyay, S.; Chinellato, D. D.; Cindolo, F.; Das, D.; Das, K.; Das-Bose, L.; De Cataldo, G.; Di Bari, D.; Di Mauro, A.; Futó, E.; Garcia, E.; Hamar, G.; Harton, A.; Jimenez, R. T.; Kim, D. W.; Kim, J. S.; Knospe, A.; Kovacs, L.; Lévai, P.; Markert, C.; Martinengo, P.; Molnar, L.; Nappi, E.; Olah, L.; Pai?, G.; Pastore, C.; Patino, M. E.; Peskov, V.; Pinsky, L.; Piuz, F.; Pochybová, S.; Sgura, I.; Sinha, T.; Song, J.; Timmins, A.; Van Beelen, J. B.; Varga, D.; Volpe, G.; Weber, M.; Xaplanteris, L.; Yi, J.; Yoo, I.-K.

2013-12-01

325

Soviet atmospheric acoustics research  

SciTech Connect

The development of low observable air vehicles by the United States coupled with the historic propensity of the Soviet Union toward the defense of its borders raises the possibility of Soviet development of acoustic systems for detection and tracking of air vehicles as part of such defense. This report reviews and assesses Soviet research in atmospheric acoustics. Topics considered relevant were aircraft noise, background acoustic noise, propagation, meteorological remote sensing, microphone technology, processing of acoustic signals, and acoustic-gravity waves and ionospheric detection. This study should provide an indication of the maturity of the Soviet technology base required for the development of potential acoustic detection and tracking systems. Overall, the Soviet technology base in areas required for acoustic aircraft detection and tracking is at least comparable to that in the United States, and, in some areas, more advanced.

McKenney, B.L.; McGrain, M. (eds.); Bass, H.E.; Lacoss, R.T.; Landers, T.E.; Powell, A.; Raspet, R.; Revell, J.D.

1990-08-01

326

Acoustical standards news.  

PubMed

American National Standards (ANSI Standards) developed by Accredited Standards Committees S1, S2, S3, S3/SC 1, and S12 in the areas of acoustics, mechanical vibration and shock, bioacoustics, animal bioacoustics, and noise, respectively, are published by the Acoustical Society of America (ASA). In addition to these standards, ASA publishes catalogs of Acoustical Standards, both National and International. To receive copies of the latest Standards catalogs, please contact Susan B. Blaeser.Comments are welcomed on all material in Acoustical Standards News.This Acoustical Standards News section in JASA, as well as the National and International Catalogs of Acoustical Standards, and other information on the Standards Program of the Acoustical Society of America, are available via the ASA home page: http://acousticalsociety.org. PMID:25373988

Blaeser, Susan B; Schomer, Paul D

2014-11-01

327

Nonequilibrium magnetization dynamics of gadolinium studied by magnetic linear dichroism in time-resolved 4f core-level photoemission.  

PubMed

The magnetic linear dichroism of the gadolinium 4f core level is studied in a time-resolved photoemission experiment employing laser pump- and synchrotron-radiation probe pulses. Upon optical excitation of the 5d6s valence electrons with femtosecond laser pulses, the magnetic order in the 4f spin system is reduced. Remarkably, the linear dichroism remains at 80% of the equilibrium contrast while the lattice temperature reaches the Curie temperature due to electron-phonon scattering. Contrasting itinerant ferromagnets, this shows that equilibration between the lattice and spin subsystems takes in Gd about 80 ps and is established in parallel with heat diffusion. PMID:18352227

Melnikov, A; Prima-Garcia, H; Lisowski, M; Giessel, T; Weber, R; Schmidt, R; Gahl, C; Bulgakova, N M; Bovensiepen, U; Weinelt, M

2008-03-14

328

Structural, magnetic, and electrochemical properties of the high pressure form of Na2Co[PO4]F.  

PubMed

The new compound HP-Na2Co[PO4]F was synthesized by high pressure solid state reaction and its crystal structure was determined from single crystal X-ray diffraction data. The physical properties of HP-Na2Co[PO4]F were characterized by magnetic susceptibility, specific heat capacity, galvanometric cycling, and electrochemical impedance spectroscopy measurements. HP-Na2Co[PO4]F crystallizes with the space group P63/m, a = 10.5484(15), c = 6.5261(9) Å, V = 628.87(15) Å(3) and Z = 6. The crystal structure consists of infinite chains of edge-sharing CoF2O4 octahedra. The latter are interconnected through the PO4 tetrahedra forming a 3D-Co[PO4]F-framework. The six coordinated sodium atoms are distributed over three crystallographic sites (2b, 6h, and 4f). The structure of HP-[Na11/3Na23/3Na32/3]Co[PO4]F is similar to [Na11/3Na23/3Sr1/3?1/3]Ge[GeO4]O. There is only one difference; Na3 occupies the 4f (1/3, 2/3, 0.0291) atomic position, whereas the Sr occupies the 2c (1/3, 2/3, 1/4) atomic position. The magnetic susceptibility follows a Curie-Weiss behavior above 50 K with ? = -21 K indicating predominant antiferromagnetic interactions. The specific heat capacity and magnetization measurements show that HP-Na2Co[PO4]F undergoes a three-dimensional magnetic ordering at TN = 11.0(1) K. The ionic conductivity ?, estimated at 350 °C, is 1.5 × 10(-7) S cm(-1). The electrochemical cycling indicates that only one sodium ion could be extracted during the first charge in Na half-cell; however, the re-intercalation was impossible due to a strong distortion of the structure after the first charge to 5.0 V. PMID:25099939

Ben Yahia, Hamdi; Mori, Daisuke; Shikano, Masahiro; Kobayashi, Hironori; Inaguma, Yoshiyuki

2014-09-28

329

Dynamic magnetic excitations in 3d and 4f atoms and clusters  

NASA Astrophysics Data System (ADS)

Spins in magnetic nanostructures can be excited by an electric current. In the inelastic scattering events, the spin of a tunneling electron provided by a scanning tunneling microscope may be flipped and angular momentum is transferred to the magnetic system. We used this technique to determine magnetic anisotropies and exchange couplings in 3d transition and 4f rare earth metal atoms and clusters on surfaces. Further, we discuss that the magnetic anisotropy, i.e. the zero field splitting, in rare earth atoms requires a fully relativistic description, in which not only the spin of the atoms but also their orbital angular momentum is taken into account. When describing the magnetic anisotropy with the Hamiltonian including all Stevens operators and combining it with spin flip scattering by conduction and tunneling electrons, we find that long spin lifetimes are theoretically expected for specific total angular momenta and crystal field symmetries and show experimental evidence that such a situation is realized in Ho on Pt(111).

Balashov, Timofey; Miyamachi, Toshio; Schuh, Tobias; Märkl, Tobias; Bresch, Christopher; Wulfhekel, Wulf

2014-12-01

330

Electron and positron scattering from perfluorocyclobutane (c-C{sub 4}F{sub 8}) molecules  

SciTech Connect

Total cross sections (TCSs) are experimentally investigated for 0.8-600-eV electron and 0.7-600-eV positron scattering from c-C{sub 4}F{sub 8} molecules using a linear transmission time-of-flight method, and a comparative study of the results is carried out in this paper. Electron-scattering differential cross sections (DCS) measurements carried out for energies 1.5-100 eV are used for a combined TCS and DCS discussion. These DCS results help to offer a better understanding of some of the structures observed in the TCSs. Fingerprints of a low-energy resonance, consistent with large electron attachment cross sections near 0 eV, have been observed below 2 eV where TCSs show a continually rising trend. Another resonance peak at {approx}8.5 eV, attributed to dissociative electron attachment with the production of fragmented ions, and a broader one at 16-40 eV, have also been observed. Except for the pronounced shoulder at {approx}40 eV, there is good qualitative agreement between the TCS result and the integrated cross-section results. Although electron TCSs are found to be generally larger than positron TCSs in the 3-120-eV ranges, these two TCSs, however, show a tendency towards merging above 120 eV.

Makochekanwa, C. [Graduate School of Sciences, Kyushu University, Fukuoka 812-8581 (Japan); Physics Department, Sofia University, Chiyoda-ku, Tokyo 102-8554 (Japan); Sueoka, O. [Department of Applied Science, Yamaguchi University, Ube 755-8611 (Japan); Kimura, M. [Graduate School of Sciences, Kyushu University, Fukuoka 812-8581 (Japan); Kitajima, M.; Tanaka, H. [Physics Department, Sofia University, Chiyoda-ku, Tokyo 102-8554 (Japan)

2005-03-01

331

Pure trinuclear 4f single-molecule magnets: synthesis, structures, magnetism and ab initio investigation.  

PubMed

A family of linear Dy(3) and Tb(3) clusters have been facilely synthesized from the reactions of DyCl(3), the polydentate 3-methyloxysalicylaldoxime (MeOsaloxH(2) ) ligand with auxiliary monoanionic ligands, such as trichloroacetate, NO(3)(-), OH(-), and Cl(-). Complexes 1-5 contain a nearly linear Ln(3) core, with similar Ln···Ln distances (3.6901(4)-3.7304(3) Å for the Dy(3) species, and 3.7273(3)-3.7485(5) Å for the Tb(3) species) and Ln···Ln···Ln angles of 157.036(8)-159.026(15)° for the Dy(3) species and 157.156(8)-160.926(15)° for the Tb(3) species. All three Ln centers are bridged by the two doubly-deprotonated [MeOsalox](2-) ligands and two of the four [MeOsaloxH](-) ligands through the N,O-?(2)-oximato groups and the phenoxo oxygen atoms (Dy-O-Dy angles=102.28(16)-106.85(13)°; Tb-O-Tb angles=102.00(11)-106.62(11)°). The remaining two [MeOsaloxH](-) ligands each chelate an outer Ln(III) center through their phenoxo oxygen and oxime nitrogen atoms. Magnetic studies reveal that both Dy(3) and Tb(3) clusters exhibit significant ferromagnetic interactions and that the Dy(3) species behave as single-molecule magnets, expanding upon the recent reports of the pure 4f type SMMs. PMID:21319238

Guo, Fu-Sheng; Liu, Jun-Liang; Leng, Ji-Dong; Meng, Zhao-Sha; Lin, Zhuo-Jia; Tong, Ming-Liang; Gao, Song; Ungur, Liviu; Chibotaru, Liviu F

2011-02-18

332

A Search for EUV Emission from the O4f Star Zeta Puppis  

NASA Technical Reports Server (NTRS)

We obtained a 140 ks EUVE observation of the O4f star, zeta Puppis. Because of its low ISM column density and highly ionized stellar wind, a unique EUV window is accessible for viewing between 128 to 140 A, suggesting that this star may he the only O star observable with the EUVE. Although no SW spectrometer wavelength bin had a signal to noise greater than 3, a bin at 136 A had a signal to noise of 2.4. This bin is where models predict the brightest line due to OV emission should occur. We present several EUV line emission models. These models were constrained by fitting the ROSAT PSPC X-ray data and our EUVE data. If the OV emission is real, the best fits to the data suggest that there are discrepancies in our current understanding of EUV/X-ray production mechanisms. In particular, the emission measure of the EUV source is found to be much greater than the total wind emission measure, suggesting that the EUV shock must produce a very large density enhancement. In addition, the location of the EUV and X-ray shocks are found to be separated by approx. 0.3 stellar radii, but the EUV emission region is found to be approx. 400 times larger than the X-ray emission region. We also discuss the implications of a null detection and present relevant upper limits.

Waldron, Wayne L.; Vallerga, John

1996-01-01

333

Anomalous Eu Valence State and Superconductivity in Undoped Eu3Bi2S4F4.  

PubMed

We have synthesized a novel europium bismuth sulfofluoride, Eu3Bi2S4F4, by solid-state reactions in sealed evacuated quartz ampules. The compound crystallizes in a tetragonal lattice (space group I4/mmm, a = 4.0771(1) Å, c = 32.4330(6) Å, and Z = 2), in which CaF2-type Eu3F4 layers and NaCl-like BiS2 bilayers stack alternately along the crystallographic c axis. There are two crystallographically distinct Eu sites, Eu(1) and Eu(2) at the Wyckoff positions 4e and 2a, respectively. Our bond valence sum calculation, based on the refined structural data, indicates that Eu(1) is essentially divalent, while Eu(2) has an average valence of ??+2.64(5). This anomalous Eu valence state is further confirmed and supported, respectively, by Mössbauer and magnetization measurements. The Eu(3+) components donate electrons into the conduction bands that are mainly composed of Bi 6px and 6py states. Consequently, the material itself shows metallic conduction and superconducts at 1.5 K without extrinsic chemical doping. PMID:25314008

Zhai, Hui-Fei; Zhang, Pan; Wu, Si-Qi; He, Chao-Yang; Tang, Zhang-Tu; Jiang, Hao; Sun, Yun-Lei; Bao, Jin-Ke; Nowik, Israel; Felner, Israel; Zeng, Yue-Wu; Li, Yu-Ke; Xu, Xiao-Feng; Tao, Qian; Xu, Zhu-An; Cao, Guang-Han

2014-10-29

334

The extreme ultraviolet emissions of W23+(4f5)  

NASA Astrophysics Data System (ADS)

In order to comply with the special challenges (open 4f-shell, configuration mixing) of simulating the spectrum of W23+ an extensive atomic model was implemented using the flexible atomic code (FAC). In detail, the basis functions from 11 configurations were used to model about 12000 levels, which give rise to roughly 60 million transitions including nearly 6 million electric and magnetic dipole transitions. A collisional radiative model has been put together which could handle the size of the input data. The modelled spectra (4-40 nm) show low sensitivity on the electron density, which validates the comparison of EBIT and tokamak spectra. The emissions between 4 and 7 nm are discussed in the context of the observations at fusion plasmas. In this range, the influence of W23+ is limited due to the small contribution to the measurement - however, elements of the presented modelling might explain the second, not understood spectral feature at 6 nm. Further details of the spectra are only briefly discussed as a close comparison to experimental data requires also models for the neighbouring ionisation stages. Additionally, the importance of configuration mixing becomes apparent motivating further investigations on neighbouring ionisation stages with similarly complex models.

Pütterich, T.; Jonauskas, V.; Neu, R.; Dux, R.; ASDEX Upgrade Team

2013-07-01

335

In vivo targeting of acoustically reflective liposomes for intravascular and transvascular ultrasonic enhancement  

Microsoft Academic Search

OBJECTIVESThe purpose of this study was to target acoustically reflective liposomes to atherosclerotic plaques in vivo for ultrasound image enhancement.BACKGROUNDWe have previously demonstrated the development of acoustically reflective liposomes that can be conjugated for site-specific acoustic enhancement. This study evaluates the ability of liposomes coupled to antibodies specific for different components of atherosclerotic plaques and thrombi to target and enhance

Sasha M. Demos; Hayat Alkan-Onyuksel; Bonnie J. Kane; Kishin Ramani; Ashwin Nagaraj; Rodney Greene; Melvin Klegerman; David D. McPherson

1999-01-01

336

Acoustics 08 Paris Finite element modeling of thermoviscous acoustics in  

E-print Network

Acoustics 08 Paris 2469 Finite element modeling of thermoviscous acoustics in closed cavities N, published in "Acoustics'08 Paris, Paris : France (2008)" #12;Acoustics 08 Paris 2470 A numerical methodology is presented to compute the acoustic field in a closed domain filled by a thermoviscous fluid, using the finite

Boyer, Edmond

337

Vowel Acoustic Space Development in Children: A Synthesis of Acoustic  

E-print Network

Vowel Acoustic Space Development in Children: A Synthesis of Acoustic and Anatomic Data Purpose: This article integrates published acoustic data on the development of vowel production. Age specific data) to create an anatomic­acoustic description of the maturation of the vowel acoustic space for English. Method

Vorperian, Houri K.

338

Effects of oxidation on structure and performance of LiVPO4F as cathode material for lithium-ion batteries  

NASA Astrophysics Data System (ADS)

In this paper, a series of LiVPO4F-based samples are prepared through sintering LiVPO4F at different temperatures under air. Experimental results show that the pristine sample is oxidized to a new compound Li1-xVPO4F1-yOz (0 4F undergoes two two-phase structural evolutions upon Li+ electrochemical extraction at average operating potentials at 4.26 and 4.30 V, corresponding to the continuous transformation of LiVPO4F ? Li0.72VPO4F ? VPO4F in the first charge process. In the reverse discharge process, there is only one two-phase structural transition VPO4F ? LiVPO4F without the appearance of the intermediate phase Li0.72VPO4F on Li+ insertion reaction at 4.18 V. Therefore, the extraction/insertion process of LiVPO4F is an asymmetrical phase transformation. When the sintering temperature is raised to 550 °C, Li1-xVPO4F1-yOz exhibits extremely poor electrochemical performance, which is attributed to the volatilization loss of lithium and the replacement of fluorine by oxygen in the structure during the sintering process under air. However, Li1-xVPO4F1-yOz has a very stable structure during the whole process of galvanostatic charge/discharge cycles as confirmed by in-situ X-ray diffraction technique.

Ma, Rui; Shao, Lianyi; Wu, Kaiqiang; Shui, Miao; Wang, Dongjie; Long, Nengbing; Ren, Yuanlong; Shu, Jie

2014-02-01

339

Lithium transition metal fluorophosphates (Li{sub 2}CoPO{sub 4}F and Li{sub 2}NiPO{sub 4}F) as cathode materials for lithium ion battery from atomistic simulation  

SciTech Connect

Lithium transition metal fluorophosphates (Li{sub 2}MPO{sub 4}F, M: Co and Ni) have been investigated from atomistic simulation. In order to predict the characteristics of these materials as cathode materials for lithium ion batteries, structural property, defect chemistry, and Li{sup +} ion transportation property are characterized. The core–shell model with empirical force fields is employed to reproduce the unit-cell parameters of crystal structure, which are in good agreement with the experimental data. In addition, the formation energies of intrinsic defects (Frenkel and antisite) are determined by energetics calculation. From migration energy calculations, it is found that these flurophosphates have a 3D Li{sup +} ion diffusion network forecasting good Li{sup +} ion conducting performances. Accordingly, we expect that this study provides an atomic scale insight as cathode materials for lithium ion batteries. - Graphical abstract: Lithium transition metal fluorophosphates (Li{sub 2}CoPO{sub 4}F and Li{sub 2}NiPO{sub 4}F). Display Omitted - Highlights: • Lithium transition metal fluorophosphates (Li{sub 2}MPO{sub 4}F, M: Co and Ni) are investigated from classical atomistic simulation. • The unit-cell parameters from experimental studies are reproduced by the core–shell model. • Li{sup +} ion conducting Li{sub 2}MPO{sub 4}F has a 3D Li{sup +} ion diffusion network. • It is predicted that Li/Co or Li/Ni antisite defects are well-formed at a substantial concentration level.

Lee, Sanghun, E-mail: sh0129.lee@samsung.com; Park, Sung Soo, E-mail: sung.s.park@samsung.com

2013-08-15

340

Comment on paper entitled, "An inversion of Freedman's 'image pulse' model in air". Acoust. Soc. Am. 119(2), 965-975 (2006).  

PubMed

Echolocation (i.e., perceiving objects using acoustic echoes) is well-known in underwater detection and to a lesser extent in robot guidance and machine perception. The paper by Tsakiris and McKerrow is concerned with machine perception in air using Freedman's asymptotic model, which was originally developed to predict the backscattering multiple-echo effect observed in sonar detection. This effect was subsequently shown to be due to the elastic response of underwater targets. Freedman's model can be used in air because the acoustic target is assumed to be rigid. Also, the model's prediction of multiple echoes can be used to obtain information about the shape of the target. This is the so-called inversion of the Freedman model by Tsakiris and McKerrow. In their paper, various simple bodies are tested in air using ultrasound and it is shown that the model provides relatively poor information about body shape. Several explanations are given. However, one explanation is not considered, namely that the model itself is not satisfactory. First, there is poor agreement with exact backscattering theory. Second, deriving information about target shape from the multiple echoes predicted by the model is a highly questionable procedure. Both these aspects are examined here. PMID:16938943

Hickling, Robert; Gaunaurd, Guillermo C

2006-08-01

341

Theoretical modeling of the uranium 4f XPS for U(VI) and U(IV) oxides  

SciTech Connect

X-ray photoelectron spectroscopy (XPS), and in particular the U4f level, has been widely used to elucidate the chemical state of uranium in various materials. In large part, previous experimental work has relied on comparing the U4f spectra of an unknown to some “standard” or using qualitative intuitive judgments on the expected behavior of the primary lines and satellite structures as a function of oxidation state and bonding environment. Such approaches are useful and can be sufficiently robust to make defensible claims. Nonetheless, there is no quantitative understanding of the chemistry and physics that control satellite structures or even the shape of the primary peaks. To address this issue, we used a rigorous, strictly ab initio theoretical approach to investigate the U(4f) XPS of U oxides with formal U(VI) and U(IV) oxidation states. Our theoretical studies are based on the electronic structures of embedded cluster models, where bonding between U and O is explicitly incorporated. We demonstrate that treatment of the many-body character of the cluster wavefunctions is essential to correctly model and interpret the U4f XPS. Here we definitively show that shake configurations, where an electron is transferred from a dominantly O2p bonding orbital into dominantly 5f or 6d antibonding orbitals, are indeed responsible for the major satellite features. Based on this rigorous theoretical framework, it is possible to establish quantitative relationships between features of the XPS spectra and the chemistry of the material.

Bagus, Paul S.; Nelin, Constance J.; Ilton, Eugene S.

2013-12-28

342

Attacking a Nexus of the Oncogenic Circuitry by Reversing Aberrant eIF4F-Mediated Translation  

PubMed Central

Notwithstanding their genetic complexity, different cancers share a core group of perturbed pathways converging upon a few regulatory nodes that link the intracellular signaling network with the basic metabolic machinery. The clear implication of this view for cancer therapy is that instead of targeting individual genetic alterations one-by-one, the next generation of cancer therapeutics will target critical hubs in the cancer network. One such hub is the translation initiation complex eIF4F, which integrates several cancer-related pathways into a self-amplifying signaling system. When hyperactivated by apical oncogenic signals, the eIF4F-driven translational apparatus selectively switches the translational repertoire of a cell towards malignancy. This central integrative role of pathologically activated eIF4F has motivated the development of small molecule inhibitors to correct its function. A genome-wide, systems-level means to objectively evaluate the pharmacological response to therapeutics targeting eIF4F remains an unmet challenge. PMID:22572598

Bitterman, Peter B.; Polunovsky, Vitaly A.

2012-01-01

343

Engineering Magnetic Anisotropy in Nanostructured 3d and 4f Ferromagnets  

NASA Astrophysics Data System (ADS)

Due to the increased demand for clean energy in recent years, there is a need for the scientific community to develop technology to harvest thermal energy which is ubiquitous but mostly wasted in our environment. However, there is still no efficient approach to harvest thermal energy to date. In this study, the theory of thermomagnetic energy harvesting is reviewed and unique applications of multiferroics (ferromagnetic plus ferroelectric) are introduced. Based on an efficiency analysis using experimentally measured magneto-thermal properties of 3d transitional and 4f rare earth ferromagnetic elements, the idea of using single domain ferromagnetic elements to obtain higher thermomagnetic conversion efficiencies is proposed. In order to fabricate a ferromagnetic single domain, the magnetic anisotropy of gadolinium (Gd) and nickel (Ni) is engineered at the nanoscale. Both thin films and nanostructures are fabricated and characterized with a focus on the change of magnetic anisotropy governed by shape, crystal structure, and strain. The fabrication processes include sputtering, e-beam lithography (writing and evaporation), and focused ion beam milling. Characterization techniques involving atomic/magnetic force microscopy, energy dispersive X-ray spectroscopy, magneto-optical Kerr effect magnetometry, superconducting quantum interference device magnetometry, scanning/transmission electron microscopy, and X-ray diffraction will also be discussed. Experimental results show that the magnetic domain structure of nanostructured Ni can be stably controlled with geometric constraints or by strain induced via electric field. The magnetic properties of nanostructured Gd, on the other hand, is sensitive to crystal structure. These results provide critical information toward the use of ferromagnetic nanostructures in thermomagnetic energy harvesting and multiferroic applications.

Hsu, Chin-Jui

344

eIF4F is a nexus of resistance to anti-BRAF and anti-MEK cancer therapies.  

PubMed

In BRAF(V600)-mutant tumours, most mechanisms of resistance to drugs that target the BRAF and/or MEK kinases rely on reactivation of the RAS-RAF-MEK-ERK mitogen-activated protein kinase (MAPK) signal transduction pathway, on activation of the alternative, PI(3)K-AKT-mTOR, pathway (which is ERK independent) or on modulation of the caspase-dependent apoptotic cascade. All three pathways converge to regulate the formation of the eIF4F eukaryotic translation initiation complex, which binds to the 7-methylguanylate cap (m(7)G) at the 5' end of messenger RNA, thereby modulating the translation of specific mRNAs. Here we show that the persistent formation of the eIF4F complex, comprising the eIF4E cap-binding protein, the eIF4G scaffolding protein and the eIF4A RNA helicase, is associated with resistance to anti-BRAF, anti-MEK and anti-BRAF plus anti-MEK drug combinations in BRAF(V600)-mutant melanoma, colon and thyroid cancer cell lines. Resistance to treatment and maintenance of eIF4F complex formation is associated with one of three mechanisms: reactivation of MAPK signalling, persistent ERK-independent phosphorylation of the inhibitory eIF4E-binding protein 4EBP1 or increased pro-apoptotic BCL-2-modifying factor (BMF)-dependent degradation of eIF4G. The development of an in situ method to detect the eIF4E-eIF4G interactions shows that eIF4F complex formation is decreased in tumours that respond to anti-BRAF therapy and increased in resistant metastases compared to tumours before treatment. Strikingly, inhibiting the eIF4F complex, either by blocking the eIF4E-eIF4G interaction or by targeting eIF4A, synergizes with inhibiting BRAF(V600) to kill the cancer cells. eIF4F not only appears to be an indicator of both innate and acquired resistance but also is a promising therapeutic target. Combinations of drugs targeting BRAF (and/or MEK) and eIF4F may overcome most of the resistance mechanisms arising in BRAF(V600)-mutant cancers. PMID:25079330

Boussemart, Lise; Malka-Mahieu, Hélène; Girault, Isabelle; Allard, Delphine; Hemmingsson, Oskar; Tomasic, Gorana; Thomas, Marina; Basmadjian, Christine; Ribeiro, Nigel; Thuaud, Frédéric; Mateus, Christina; Routier, Emilie; Kamsu-Kom, Nyam; Agoussi, Sandrine; Eggermont, Alexander M; Désaubry, Laurent; Robert, Caroline; Vagner, Stéphan

2014-09-01

345

Acoustic rainbow trapping  

PubMed Central

Spatial modulation of sound velocity below the wavelength scale can introduce strong frequency-dependent acoustic responses in tailored composite materials, regardless the fact that most natural bulk materials have negligible acoustic dispersions. Here, for the first time, we experimentally demonstrate a metamaterial that traps broadband acoustic waves and spatially separates different frequency components, as the result of dispersion and wave velocity control by designed gradient subwavelength structures. The trapping positions can be predicted by the microscopic picture of balanced interplay between the acoustic resonance inside individual apertures and the mutual coupling among them. With the enhanced wave-structure interactions and the tailored frequency responses, such metamaterial allows precise spatial-spectral control of acoustic waves and opens new venue for high performance acoustic wave sensing, filtering, and nondestructive metrology.

Zhu, Jie; Chen, Yongyao; Zhu, Xuefeng; Garcia-Vidal, Francisco J.; Yin, Xiaobo; Zhang, Weili; Zhang, Xiang

2013-01-01

346

Acoustic flowmeters for pipelines  

Microsoft Academic Search

Acoustic flowmeters offer high accuracy and long-term stability in measuring pipeline flows of natural gas. These devices use acoustic transducers to measure the velocity of acoustic signals propagated through the flow at an angle of 30°⁻⁶⁵sup 0\\/, depending on the available space and the accuracy requirements. A processing unit attached to the transducers by cable computes the flow rate from

F. C. Jr. Lowell; F. Hirschfeld

1979-01-01

347

Low frequency acoustic microscope  

DOEpatents

A scanning acoustic microscope is disclosed for the detection and location of near surface flaws, inclusions or voids in a solid sample material. A focused beam of acoustic energy is directed at the sample with its focal plane at the subsurface flaw, inclusion or void location. The sample is scanned with the beam. Detected acoustic energy specularly reflected and mode converted at the surface of the sample and acoustic energy reflected by subsurface flaws, inclusions or voids at the focal plane are used for generating an interference signal which is processed and forms a signal indicative of the subsurface flaws, inclusions or voids.

Khuri-Yakub, Butrus T. (Palo Alto, CA)

1986-11-04

348

Acoustic Doppler Current Profilers  

USGS Multimedia Gallery

USGS Hydrologic Instrumentation Facilities employee Jerry Gardner and contract employee Rodger Cook, prepare recently acquired Acoustic Doppler Profilers for distribution to USGS Water Science Centers....

2009-08-04

349

The revised human liver cytochrome P450 "Pie": absolute protein quantification of CYP4F and CYP3A enzymes using targeted quantitative proteomics.  

PubMed

The CYP4F subfamily of enzymes has been identified recently to be involved in the metabolism of endogenous compounds (arachidonic acid and leukotriene B4), nutrients (vitamins K1 and E), and xenobiotics (pafuramidine and fingolimod). CYP4F2 and CYP4F3B are reported to be expressed in the human liver. However, absolute concentrations of these enzymes in human liver microsomes (HLMs) and their interindividual variability have yet to be determined because of the lack of specific antibodies. Here, an liquid chromatography with tandem mass spectrometry (LC-MS/MS)-based targeted quantitative proteomic approach was employed to determine the absolute protein concentrations of CYP4F2 and CYP4F3B compared with CYP3A in two panels of HLMs (n = 31). As a result, the human hepatic cytochrome P450 (P450) "pie" has been revised to include the contribution of CYP4F enzymes, which amounts to 15% of the total hepatic cytochrome P450 enzymes. CYP4F3B displayed low interindividual variability (3.3-fold) in the HLM panels whereas CYP4F2 displayed large variability (21-fold). However, CYP4F2 variability decreased to 3.4-fold if the two donors with the lowest expression were excluded. In contrast, CYP3A exhibited 29-fold interindividual variability in the same HLM panels. The proposed marker reaction for CYP4F enzymes pafuramidine/DB289 M1 formation did not correlate with CYP4F protein content, suggesting alternate metabolic pathways for DB289 M1 formation in HLMs. In conclusion, CYP4F enzymes are highly expressed in the human liver and their physiologic and pharmacologic roles warrant further investigation. PMID:24816681

Michaels, Scott; Wang, Michael Zhuo

2014-08-01

350

All-optical adaptive scanning acoustic microscope.  

PubMed

We have constructed a fast laser-based surface acoustic wave (SAW) microscope, which may be thought of as a non-perturbing scanning acoustic microscope. The instrument is capable of rapid high resolution vector contrast imaging at several discrete frequencies, without any damage to the sample. Tailoring the generating optical distribution using computer-generated holograms allows us to both focus the acoustic waves (increasing their amplitude) and to spread the optical power over the sample surface (preventing damage). Accurate quantitative amplitude and phase (velocity) measurements and unique acoustic contrast mechanisms are possible with our instrument based on this technology due to the non-perturbing nature and the instrument geometries.However, the complexity of the optical generation profile leads to a strong dependence on material properties such as the SAW velocity and material anisotropy. We address these issues in this paper, and demonstrate how a spatial light modulator may be used to adapt the generating optical distribution to compensate for the material properties. This facilitates simpler alignment and velocity matching, and, combined with an acoustic wavefront sensor, will allow real-time adjustment of the generating source to enable imaging on anisotropic materials. PMID:12782262

Sharples, Steve D; Clark, Matt; Somekh, Mike G

2003-06-01

351

Post Treatment of Acoustic Neuroma  

MedlinePLUS

... Report Acoustic Neuroma Legacy Society Search ANAUSA.org Post-Treatment Surgical removal of an acoustic neuroma is ... results provide information regarding symptoms, diagnosis, treatment and post-treatment issues experienced by acoustic neuroma patients. Click ...

352

Vortex-driven acoustically coupled combustion instabilities  

Microsoft Academic Search

Combustion instability is investigated in the case of a multiple-inlet combustor with dump. It is shown that low-frequency instabilities are acoustically coupled and occur at the eigenfrequencies of the system. Using spark-schlieren and a special phase-average imaging of the C2-radical emission, the fluid-mechanical processes involved in a vortex-driven mode of instability are investigated. The phase-average images provide maps of the

Thierry J. Poinsot; Arnaud C. Trouve; Denis P. Veynante; Sebastien M. Candel; Emile J. Esposito

1987-01-01

353

Absorption spectral analysis of 4f-4f transitions for the complexation of Pr(III) and Nd(III) with thiosemicarbazide in absence and presence of Zn(II) in aqueous and organic solvents.  

PubMed

The complexation of thiosemicarbazide with Pr(III) and Nd(III) in absence and presence of Zn(II), a soft metal ion in aqueous and organic solvents like CH(3)OH,CH(3)CN, dioxane (C(4)H(8)O(2)) and DMF (C(3)H(7)NO) and their equimolar mixtures are discussed by employing absorption difference and comparative absorption spectrophotometry. Complexation of thiosemicarbazide with Pr(III) and Nd(III) is indicated by the changes in the absorption intensity following the subsequent changes in the oscillator strength of different 4f-4f bands and Judd-Ofelt intensity (T(?)) parameters. The other spectral parameters like energy interaction parameters namely Slater-Condon (F(k)), Racah (E(k)), Lande (?(4f)), Nephelauxetic ratio (?) and bonding parameters (b(1/2)) are further computed to explain the nature of complexation. The difference in the energy parameters with respect to donor atoms and solvents reveal that the chemical environment around the lanthanide ions has great impact on f-f transition and any change in the environment result in modification of the spectra. Various solvents and their equimolar mixtures are also used to discuss the participation of solvents in the complexation. PMID:21723187

Anita, K; Rajmuhon Singh, N

2011-10-15

354

A Klein-Gordon acoustic theory  

SciTech Connect

Geophysicists do not associate traveltime variation with density variation in acoustic or elastic wavefield interpretation. Rather, given a constant index of refraction, density variation within the medium of propagation is associated only with amplitudes. This point of view prevails because density does not occur as a variable in classical results such as Snell's Law or the eikonal equation. Nevertheless, in this paper I predict, analytically, a continuum of density effects on acoustic wavefields-including a dispersive traveltime delay when density variation is rapid. I also examine the ability of a common imaging algorithm to cope with this time delay.

Anno, P.D.

1992-12-01

355

A Klein-Gordon acoustic theory  

SciTech Connect

Geophysicists do not associate traveltime variation with density variation in acoustic or elastic wavefield interpretation. Rather, given a constant index of refraction, density variation within the medium of propagation is associated only with amplitudes. This point of view prevails because density does not occur as a variable in classical results such as Snell`s Law or the eikonal equation. Nevertheless, in this paper I predict, analytically, a continuum of density effects on acoustic wavefields-including a dispersive traveltime delay when density variation is rapid. I also examine the ability of a common imaging algorithm to cope with this time delay.

Anno, P.D.

1992-12-01

356

New Sensors For Flow Velocity And Acoustics  

NASA Technical Reports Server (NTRS)

Paper describes two sensor-development programs at Fluid Mechanics Laboratory at NASA Ames Research Center. One program for digital image velocimetry (DIV) sensors, and other program, for advanced acoustic sensors for wind tunnels. DIV measures, in real time, instantaneous velocity fields of time-varying flow or of collection of objects moving with varying velocities. Advanced acoustic sensors for wind tunnels being developed to reduce effects of interference from wind noise, noise from interactions between flows and sensors, flow-induced vibrations of sensors, deflections of accoustic waves by boundary layers induced by sensors, and reflections from walls and sensor supports.

Cho, Y. C.

1991-01-01

357

Research in acoustic and optical wave technology  

NASA Astrophysics Data System (ADS)

This report summaries the research progress and activity 1 April 1981 through 31 March 1982. Specific Projects are: (81-1) Interaction of Acoustic and Optical Waves with Domains in Ferroic Fibers with Bulk Materials: (B.A. Auld); (81-2) High T Josephson Junctions & Circuits (M. R. Beasley); (81-3) Optical & Nonlinear Optical Studies of Single Crystal Fibers (R. L. Byer); (81-4) Acoustic Surface Wave Scanning of Optical Images, (G. S. Kino); (81-5) Picosecond Raman Studies of Electronic Solids (A. E. Siegman).

Siegman, A. E.; Auld, B. A.; Kino, G. S.; Beasley, M. R.; Byer, R. L.

1982-04-01

358

Acoustics Critical Readiness Review  

NASA Technical Reports Server (NTRS)

This presentation reviews the status of the acoustic equipment from the medical operations perspective. Included is information about the acoustic dosimeters, sound level meter, and headphones that are planned for use while on orbit. Finally there is information about on-orbit hearing assessments.

Ballard, Kenny

2010-01-01

359

The accidental (acoustical) tourist  

Microsoft Academic Search

The acoustical phenomenon observed at an ancient temple in the Great Ball Court at Chichen Itza was described as ''little short of amazing--an ancient whispering gallery'' by Silvanus G. Morley, leader of the Carnegie Institute's archaeological team that excavated and restored these structures in the 1920s. Since then, many others have experienced the extraordinary acoustics at Chichen Itza and other

Wayne Van Kirk

2002-01-01

360

Advances in atmospheric acoustics  

Microsoft Academic Search

We give a detailed review of developments in atmospheric acoustics of the last decade. These developments include new ways to use refractive effects, studies of phase and amplitude fluctuations during propagation of sound along a path, nonlinear effects near high-powered acoustic antennas, problems related to noise, insights into large-scale atmospheric processes gained from infrasound, applications dependent on the Doppler frequency

Edmund H. Brown; Freeman F. Hall

1978-01-01

361

Advances in atmospheric acoustics  

Microsoft Academic Search

A detailed review of developments in atmospheric acoustics of the last decade is given. These developments include new ways to use refractive effects, studies of phase and amplitude fluctuations during propagation of sound along a path, nonlinear effects near high-powered acoustic antennas, problems related to noise, insights into large-scale atmospheric processes gained from infrasound, applications dependent on the Doppler frequency

E. H. Brown; Freeman F. Hall

1978-01-01

362

Progesterone and Mifepristone Regulate L-Type Amino Acid Transporter 2 and 4F2 Heavy Chain Expression in Uterine Leiomyoma Cells  

PubMed Central

Context: Progesterone and its receptor (PR) play key roles in uterine leiomyoma growth. Previously, using chromatin immunoprecipitation-based cloning, we uncovered L-type amino acid transporter 2 (LAT2) as a novel PR target gene. LAT2 forms heterodimeric complexes with 4F2 heavy chain (4F2hc), a single transmembrane domain protein essential for LAT2 to exert its function in the plasma membrane. Until now, little is known about the roles of LAT2/4F2hc in the regulation of the growth of human uterine leiomyoma. Objective: The aim of the study is to investigate the regulation of LAT2 and 4F2hc by progesterone and the antiprogestin mifepristone and their functions in primary human uterine leiomyoma smooth muscle (LSM) cells and tissues from 39 premenopausal women. Results: In primary LSM cells, progesterone significantly induced LAT2 mRNA levels, and this was blocked by cotreatment with mifepristone. Progesterone did not alter 4F2hc mRNA levels, whereas mifepristone significantly induced 4F2hc mRNA expression. Small interfering RNA knockdown of LAT2 or 4F2hc markedly increased LSM cell proliferation. LAT2, PR-B, and PR-A levels were significantly higher in freshly isolated LSM cells vs. adjacent myometrial cells. In vivo, mRNA levels of LAT2 and PR but not 4F2hc were significantly higher in leiomyoma tissues compared with matched myometrial tissues. Conclusion: We present evidence that progesterone and its antagonist mifepristone regulate the amino acid transporter system LAT2/4F2hc in leiomyoma tissues and cells. Our findings suggest that products of the LAT2/4F2hc genes may play important roles in leiomyoma cell proliferation. We speculate that critical ratios of LAT2 to 4F2hc regulate leiomyoma growth. PMID:19808856

Luo, Xia; Yin, Ping; Reierstad, Scott; Ishikawa, Hiroshi; Lin, Zhihong; Pavone, Mary Ellen; Zhao, Hong; Marsh, Erica E.; Bulun, Serdar E.

2009-01-01

363

Acoustics of a planetarium  

NASA Astrophysics Data System (ADS)

Brigham Young University has recently constructed a planetarium with a 38-ft.-diameter dome. The facility also serves as a classroom. Since planetariums typically have poor acoustics due to their domed ceiling structures, acoustical recommendations were requested before its construction. The recommendations were made in an attempt to create an acceptable listening environment for lectures and other listening events. They were based in part on computer models and auralizations intended to predict the effectiveness of several acoustical treatments on the outer walls and on the dome itself. The recommendations were accepted and the planetarium was completed accordingly. A series of acoustical measurements was subsequently made in the room and the resulting acoustical parameters were mapped over the floor plan. This paper discusses these results and compares them with the predictions of the computer models.

Shepherd, Micah; Leishman, Timothy W.; Utami, Sentagi

2005-09-01

364

Improved acoustic emission locations  

NASA Technical Reports Server (NTRS)

A technique for locating acoustic emission in brittle rock specimens is described. An array of eight piezoelectric transducers was used to detect acoustic emission and to receive velocity measurement pulses. Axial and transverse velocities were calculated from the transmission data; the use of the velocity data to locate the acoustic emissions is discussed. Waveforms were recorded for about 140 acoustic emissions during the deformation of the Westerly granite specimen and about 100 acoustic emissions were located. The effect of transducer size and incident angle on apparent arrival times is evaluated using a lead zirconium titinate transducer bonded to a small brass rider with a curved surface matched to the brass specimen. The relation between location accuracy in various regions of the specimen and the geometry of the receiver array is studied. It is observed that for incidence angles away from the normal, the velocity appears to be higher than for normal incidences.

Getting, I. C.; Roecken, C.; Spetzler, H.

1986-01-01

365

Virtual acoustics displays  

NASA Technical Reports Server (NTRS)

The real time acoustic display capabilities are described which were developed for the Virtual Environment Workstation (VIEW) Project at NASA-Ames. The acoustic display is capable of generating localized acoustic cues in real time over headphones. An auditory symbology, a related collection of representational auditory 'objects' or 'icons', can be designed using ACE (Auditory Cue Editor), which links both discrete and continuously varying acoustic parameters with information or events in the display. During a given display scenario, the symbology can be dynamically coordinated in real time with 3-D visual objects, speech, and gestural displays. The types of displays feasible with the system range from simple warnings and alarms to the acoustic representation of multidimensional data or events.

Wenzel, Elizabeth M.; Fisher, Scott S.; Stone, Philip K.; Foster, Scott H.

1991-01-01

366

Highly directional acoustic receivers.  

PubMed

The theoretical directivity of a single combined acoustic receiver, a device that can measure many quantities of an acoustic field at a collocated point, is presented here. The formulation is developed using a Taylor series expansion of acoustic pressure about the origin of a Cartesian coordinate system. For example, the quantities measured by a second-order combined receiver, denoted a dyadic sensor, are acoustic pressure, the three orthogonal components of acoustic particle velocity, and the nine spatial gradients of the velocity vector. The power series expansion, which can be of any order, is cast into an expression that defines the directivity of a single receiving element. It is shown that a single highly directional dyadic sensor can have a directivity index of up to 9.5 dB. However, there is a price to pay with highly directive sensors; these sensors can be significantly more sensitive to nonacoustic noise sources. PMID:12656387

Cray, Benjamin A; Evora, Victor M; Nuttall, Albert H

2003-03-01

367

k Dependence of the crystal-field splittings of 4f states in rare-earth systems.  

PubMed

The occupation, energy separation, and order of the crystal-field-split 4f states are crucial for the understanding of the magnetic properties of rare-earth systems. We provide the experimental evidence that crystal-field-split 4f states exhibit energy dispersion in momentum space leading to variations of energy spacings between them and even of their energy sequence across the Brillouin zone. These observations were made by performing angle-resolved photoemission experiments on YbRh(2)Si(2) and properly simulated within a simple model based on results obtained by inelastic neutron scattering experiments and band structure calculations. Our findings should be generally applicable to rare-earth systems and have considerable impact on the understanding of magnetism and related phenomena. PMID:21231502

Vyalikh, D V; Danzenbächer, S; Kucherenko, Yu; Kummer, K; Krellner, C; Geibel, C; Holder, M G; Kim, T K; Laubschat, C; Shi, M; Patthey, L; Follath, R; Molodtsov, S L

2010-12-01

368

BDNF gene therapy induces auditory nerve survival and fiber sprouting in deaf Pou4f3 mutant mice  

PubMed Central

Current therapy for patients with hereditary absence of cochlear hair cells, who have severe or profound deafness, is restricted to cochlear implantation, a procedure that requires survival of the auditory nerve. Mouse mutations that serve as models for genetic deafness can be utilized for developing and enhancing therapies for hereditary deafness. A mouse with Pou4f3 loss of function has no hair cells and a subsequent, progressive degeneration of auditory neurons. Here we tested the influence of neurotrophin gene therapy on auditory nerve survival and peripheral sprouting in Pou4f3 mouse ears. BDNF gene transfer enhanced preservation of auditory neurons compared to control ears, in which nearly all neurons degenerated. Surviving neurons in treated ears exhibited pronounced sprouting of nerve fibers into the auditory epithelium, despite the absence of hair cells. This enhanced nerve survival and regenerative sprouting may improve the outcome of cochlear implant therapy in patients with hereditary deafness. PMID:23150788

Fukui, H.; Wong, H. T.; Beyer, L. A.; Case, B. G.; Swiderski, D. L.; Di Polo, A.; Ryan, A. F.; Raphael, Y.

2012-01-01

369

Copper deposition onto silicon by galvanic displacement: Effect of Cu complex formation in NH 4F solutions  

Microsoft Academic Search

Copper was deposited onto rotating Si substrates by galvanic displacement in 6.0M NH4F to determine the effects of Cu complex formation on deposition rates. Deposition rates decreased with increasing rotation speed, indicating that Cu(I) intermediates, stabilized by NH3, diffuse away from the Cu surface before they reduce to Cu(0). UV–visible spectra of contacting solutions and direct measurements of mass changes

Calvin P. daRosa; Enrique Iglesia; Roya Maboudian

2009-01-01

370

Successful sex ratio of 1M:4F in the astacid crayfish Pacifastacus leniusculus Dana under captive breeding conditions  

Microsoft Academic Search

In astacid crayfish breeding, a sex ratio of one male to two females (1M:2F) is usually recommended. In light of the fact that an increase in the proportion of females in the broodstock would be desirable, two experiments were carried out with Pacifastacus leniusculus Dana to test a proportion of females with a ratio as high as 1M:4F under different

J. D. Celada; J. I. Antolín; J. M. Carral; M. Sáez-Royuela; R. Rodríguez

2005-01-01

371

A mutation in periaxin is responsible for CMT4F, an autosomal recessive form of Charcot-Marie-Tooth disease  

Microsoft Academic Search

Charcot-Marie-Tooth (CMT) disease is a hetero- geneous group of inherited peripheral motor and sensory neuropathies characterized by chronic distal weakness with progressive muscular atrophy and sensory loss in the distal extremities. Inheritance can be autosomal dominant, X-linked or autosomal recessive (ARCMT). Recently, a locus responsible for a demyelinating form of ARCMT disease, named CMT4F, has been mapped on 19q13 in

Angèle Guilbot; Anna Williams; Nicole Ravisé; Christophe Verny; Alexis Brice; Diane L. Sherman; Peter J. Brophy; Eric LeGuern

2001-01-01

372

Nuclear magnetic resonance of Al-27 in topaz, Al2SiO4/F, OH/2.  

NASA Technical Reports Server (NTRS)

The Al-27 nuclear quadrupolar coupling constant and asymmetry parameter (eta) in topaz have been determined to be 1.67 (plus or minus 0.03) MHz and 0.38 plus or minus 0.05, respectively. These values and the orientations of the principal axes are consistent with the Fe(3+) paramagnetic resonance data and with the symmetry of the AlO4F2 octahedron.

Tsang, T.; Ghose, S.

1972-01-01

373

Oxide Etch Behavior in an Inductively Coupled C4F8 Discharge Characterized by Diode Laser Spectroscopy.  

NASA Astrophysics Data System (ADS)

This study reports on oxide and photoresist etch characteristics in an inductively coupled GEC Reference Cell as a function of reactor source power, bias power and pressure using C4F8. Diode laser absorption spectroscopy (DLAS) has shown that C4F8 is largely dissociated to form C2F4, CF2 and CF in the discharge. Over an oxide surface, CF2 and CF are consumed in the oxide etch process, but only when the bias power is sufficient to keep the oxide surface clean through energetic ion bombardment. For C4F8, this transition occurs at 60 eV (75 W bias power) in the GEC Cell. At higher bias powers (125 W) where oxide etching is fast ( 600 nm/min.), CF2 appears to be the key radical for the etch process since 50 percent (2.7-3.0 mTorr in a 15 mTorr C4F8 discharge) is consumed. These values were obtained by comparing the CF2 concentrations over non-reactive wafer surfaces versus blanket oxide wafer surfaces undergoing etching. CF is shown to display a similar trend, but its concentration is an order of magnitude less than CF2, and consequently cannot account on a mass basis for the amount of reactants necessary to balance the amount of etch products. Over a PR surface, neither CF2 nor CF concentrations vary as a function of PR etch rate. Consequently, they do not appear to be involved in the PR etch mechanism. However, PR etching is also critically dependent on bias power. PR films etch presumably due to energetic ion bombardment that degrades the PR film, making it liable to attack by fluorine.

Anderson, Harold; Barela, Marcus; Courtin, Geoff; Waters, Karla

2001-10-01

374

Ocean seismo-acoustics. Low-frequency underwater acoustics  

SciTech Connect

This book presents information on seismo-acoustic propagation in seawater and sea beds that includes theoretical developments, modelling and experiments, and fluctuations. Boundary scatteiring, seismo-acoustic waves and seismo-acoustic noise are discussed. Technology and new approaches in seismo-acoustic measurements are presented.

Akal, T.; berkson, J.M.

1986-01-01

375

Multiple components of eIF4F are required for protein synthesis-dependent hippocampal long-term potentiation  

PubMed Central

Persistent forms of synaptic plasticity are widely thought to require the synthesis of new proteins. This feature of long-lasting forms of plasticity largely has been demonstrated using inhibitors of general protein synthesis, such as either anisomycin or emetine. However, these drugs, which inhibit elongation, cannot address detailed questions about the regulation of translation initiation, where the majority of translational control occurs. Moreover, general protein synthesis inhibitors cannot distinguish between cap-dependent and cap-independent modes of translation initiation. In the present study, we took advantage of two novel compounds, 4EGI-1 and hippuristanol, each of which targets a different component of the eukaryotic initiation factor (eIF)4F initiation complex, and investigated their effects on long-term potentiation (LTP) at CA3-CA1 synapses in the hippocampus. We found that 4EGI-1 and hippuristanol both attenuated long-lasting late-phase LTP induced by two different stimulation paradigms. We also found that 4EGI-1 and hippuristanol each were capable of blocking the expression of newly synthesized proteins immediately after the induction of late-phase LTP. These new pharmacological tools allow for a more precise dissection of the role played by translational control pathways in synaptic plasticity and demonstrate the importance of multiple aspects of eIF4F in processes underlying hippocampal LTP, laying the foundation for future studies investigating the role of eIF4F in hippocampus-dependent memory processes. PMID:23054596

Hoeffer, Charles A.; Santini, Emanuela; Ma, Tao; Arnold, Elizabeth C.; Whelan, Ashley M.; Wong, Helen; Pierre, Philippe; Pelletier, Jerry

2013-01-01

376

Effect of temperature on the electron attachment and detachment properties of c-C{sub 4}F{sub 6}  

SciTech Connect

The temperature dependence of the low-energy electron attachment and autodetachment processes for c-C{sub 4}F{sub 6} in a N{sub 2} buffer gas has been studied in the temperature, T, range of 300 to 600 K and the mean electron energy, <{epsilon}>, range from 0.19 to 1.0 eV. The low-energy electron attachment rate constant for c-C{sub 4}F{sub 6} shows only a slight dependence on gas temperature. In contrast, the autodetachment frequency increases by more than four orders of magnitude when T is increased from 300 to 600 K. This increase in autodetachment is due to the increase in the internal energy content of the c-C{sub 4},F{sub 6}{sup {minus}} anion with increasing T. The autodetachment process under consideration is a heat-activated process and has an activation energy E* of 0.24 eV. Significance of these results to gaseous dielectrics is indicated.

Datskos, P.G.; Christophorou, L.G. [Oak Ridge National Lab., TN (United States)]|[Tennessee Univ., Knoxville, TN (United States). Dept. of Physics and Astronomy; Carter, J.G. [Oak Ridge National Lab., TN (United States)

1994-06-01

377

Isl1 and Pou4f2 Form a Complex to Regulate Target Genes in Developing Retinal Ganglion Cells  

PubMed Central

Precise regulation of gene expression during biological processes, including development, is often achieved by combinatorial action of multiple transcription factors. The mechanisms by which these factors collaborate are largely not known. We have shown previously that Isl1, a Lim-Homeodomain transcription factor, and Pou4f2, a class IV POU domain transcription factor, co-regulate a set of genes required for retinal ganglion cell (RGC) differentiation. Here we further explore how these two factors interact to precisely regulate gene expression during RGC development. By GST pulldown assays, co-immunoprecipitation, and electrophoretic mobility shift assays, we show that Isl1 and Pou4f2 form a complex in vitro and in vivo, and identify the domains within these two proteins that are responsible for this interaction. By luciferase assay, in situ hybridization, and RNA-seq, we further demonstrate that the two factors contribute quantitatively to gene expression in the developing RGCs. Although each factor alone can activate gene expression, both factors are required to achieve optimal expression levels. Finally, we discover that Isl1 and Pou4f2 can interact with other POU and Lim-Homeodomain factors respectively, indicating the interactions between these two classes of transcription factors are prevalent in development and other biological processes. PMID:24643061

Li, Renzhong; Wu, Fuguo; Ruonala, Raili; Sapkota, Darshan; Hu, Zihua; Mu, Xiuqian

2014-01-01

378

High-resolution electron spectroscopy of lanthanide (Ce, Pr, and Nd) complexes of cyclooctatetraene: The role of 4f electrons  

SciTech Connect

Cerium, praseodymium, and neodymium complexes of 1,3,5,7-cyclooctatetraene (COT) complexes were produced in a laser-vaporization metal cluster source and studied by pulsed-field ionization zero electron kinetic energy spectroscopy and quantum chemical calculations. The computations included the second-order Moller-Plesset perturbation theory, the coupled cluster method with single, double, and perturbative triple excitations, and the state-average complete active space self-consistent field method. The spectrum of each complex exhibits multiple band systems and is assigned to ionization of several low-energy electronic states of the neutral complex. This observation is different from previous studies of M(COT) (M = Sc, Y, La, and Gd), for which a single band system was observed. The presence of the multiple low-energy electronic states is caused by the splitting of the partially filled lanthanide 4f orbitals in the ligand field, and the number of the low-energy states increases rapidly with increasing number of the metal 4f electrons. On the other hand, the 4f electrons have a small effect on the geometries and vibrational frequencies of these lanthanide complexes.

Kumari, Sudesh; Roudjane, Mourad; Hewage, Dilrukshi; Yang Dongsheng [Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506-0055 (United States); Liu Yang [Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506-0055 (United States); Academy of Fundamental and Interdisciplinary Science, Harbin Institute of Technology, Harbin 150080 (China)

2013-04-28

379

Screening of 4f moments and delocalization in the compressed light rare earths A. K. McMahan,1 R. T. Scalettar,2 and M. Jarrell3  

E-print Network

moments by the valence electrons.25­28 The conflict between these scenarios is exag- gerated by the use and charge susceptibilities and the 4fn , 4fn-1 , and 4fn+1 configuration weights are calculated at sharp 4fn configurations, their 4f moments assume atomic-limiting values, are unscreened, and the 4f

California at Davis, University of

380

28 CFR Appendix to Part 55 - Jurisdictions Covered Under Sections 4(f)(4) and 203(c) of the Voting Rights Act of 1965, as...  

Code of Federal Regulations, 2013 CFR

...Sections 4(f)(4) and 203(c) of the Voting Rights Act of 1965, as Amended [Applicable...IMPLEMENTATION OF THE PROVISIONS OF THE VOTING RIGHTS ACT REGARDING LANGUAGE MINORITY...4(f )(4) and 203(c ) of the Voting Rights Act of 1965, as Amended...

2013-07-01

381

28 CFR Appendix to Part 55 - Jurisdictions Covered Under Sections 4(f)(4) and 203(c) of the Voting Rights Act of 1965, as...  

Code of Federal Regulations, 2012 CFR

...Sections 4(f)(4) and 203(c) of the Voting Rights Act of 1965, as Amended [Applicable...IMPLEMENTATION OF THE PROVISIONS OF THE VOTING RIGHTS ACT REGARDING LANGUAGE MINORITY...4(f )(4) and 203(c ) of the Voting Rights Act of 1965, as Amended...

2012-07-01

382

Modeling and prediction of density distribution and microstructure in particleboards from acoustic properties by correlation of non-contact high-resolution pulsed air-coupled ultrasound and X-ray images.  

PubMed

Non-destructive density and microstructure quality control testing in particleboards (PBs) is necessary in production lines. A pulsed air-coupled ultrasound (ACU) high-resolution normal transmission system, together with a first wave tracking algorithm, were developed to image amplitude transmission G(p) and velocity c(p) distributions at 120kHz for PBs of specific nominal densities and five particle geometries, which were then correlated to X-ray in-plane density images ?(s). Test PBs with a homogeneous vertical density profile were manufactured in a laboratory environment and conditioned in a standard climate (T=20°C, RH=65%) before the measurements. Continuous trends (R(2)>0.97) were obtained by matching the lateral resolution of X-ray images with the ACU sound field radius (?(w)(o)=21mm) and by clustering the scatter plots. ?(s)?c(p) was described with a three-parameter non-linear model for each particle geometry, allowing for ACU density prediction with 3% uncertainty and PB testing according to EN312. ?(s)?G(p) was modeled by calculating ACU coupling gain and by fitting inverse power laws with offset of ?(s) and c(p) to material attenuation, which scaled with particle volume. G(p) and c(p) variations with the frequency were examined, showing thickness resonances and scattering attenuation. The combination of ACU and X-ray data enabled successful particle geometry classification. The observed trends were interpreted in terms of multi-scale porosity and grain scattering with finite-difference time-domain simulations, which modeled arbitrarily complex stiffness and density distributions. The proposed method allows for non-contact determination of relations between acoustic properties and in-plane density distribution in plate materials. In future work, commercial PBs with non-uniform vertical density profiles should be investigated. PMID:22677469

Sanabria, Sergio J; Hilbers, Ulrich; Neuenschwander, Jürg; Niemz, Peter; Sennhauser, Urs; Thömen, Heiko; Wenker, Jan L

2013-01-01

383

Acoustical properties of double porosity granular materials.  

PubMed

Granular materials have been conventionally used for acoustic treatment due to their sound absorptive and sound insulating properties. An emerging field is the study of the acoustical properties of multiscale porous materials. An example of these is a granular material in which the particles are porous. In this paper, analytical and hybrid analytical-numerical models describing the acoustical properties of these materials are introduced. Image processing techniques have been employed to estimate characteristic dimensions of the materials. The model predictions are compared with measurements on expanded perlite and activated carbon showing satisfactory agreement. It is concluded that a double porosity granular material exhibits greater low-frequency sound absorption at reduced weight compared to a solid-grain granular material with similar mesoscopic characteristics. PMID:22087905

Venegas, Rodolfo; Umnova, Olga

2011-11-01

384

Syntheses and characterization of salts with the [Al(D)4F2]+ cation (D = pyridine or water).  

PubMed

Our approach for preparation of tetrakis-(pyridine)-difluoro-aluminum chloride was successfully deployed for the synthesis of corresponding Br and I compounds, respectively. By reacting AlX(3)·3Py (X = Cl, Br, I) with Me(3)SiF in pyridine, two of the three halogens X were substituted by fluorine atoms forming the "aluminum mixed halide" complexes AlF(2)X·4Py with the ionic solid-state structures [Al(Py)(4)F(2)]X. Whereas the (27)Al solid state NMR spectra of AlX(3)·3Py (X = Cl, Br) confirmed the existence of the expected singular ?(6)?(3)-Al centers in their structures, the corresponding spectrum of AlI(3)·3Py does not contain any signal that belongs to a 6-fold coordinated Al atom. The elemental analysis data strongly support the 1:2-stoichiometry of the complex (AlI(3)·2Py), which in accord to the (27)Al MAS NMR spectra possessed only one ?(4)?(3)-Al side as in the ionic structure [Al(Py)(2)I(2)]I. AlBr(3)·3Py was also transformed by pyridine into the ionic complex [Al(Py)(4)Br(2)]Br. The later was isolated from pyridine solutions, and its structure was determined by X-ray single crystal analysis. On the basis of our results, solvated [Al(Py)(n)X(2)](+) cations are most probably the dominating species in pyridine solutions of AlX(3). Thus, only two Al-X covalent bonds underwent X/F- exchange and the halogen exchange reactions were terminated at " [Al(Py)(4)F(2)](+) stage". The hydrolysis of [Al(Py)(4)F(2)]Cl by very diluted hydrochloric acid in methanol proceeded smoothly under preservation of the Al-F bonds and displacement of pyridine by water. The formation of the stable helical trans-octahedron [Al(H(2)O)(4)F(2)](+) cation was confirmed by single-crystal XRD analysis. By reacting [Al(Py)(4)F(2)]Cl with the cyclo-n-propyl-phosphonic acid anhydride [CH(3)CH(2)CH(2)-PO(2)](3), an unexpected F-migration from Al- to P- atoms was observed. PMID:23092241

Dimitrov, Anton; Heidemann, Detlef; Khallow, Khalaf I; Kemnitz, Erhard

2012-11-01

385

Some Problems of modern acoustics  

NASA Technical Reports Server (NTRS)

The multidisciplinary and interdisciplinary character of acoustics is considered and its scientific, technological, economical and social implications, as well as the role of acoustics in creating new machines and equipment and improving the quality of products are outlined. Research beyond audible frequencies, as well as to extremely high acoustic intensities, which requires the development of a nonlinear acoustics is elaborated.

Stan, A.

1974-01-01

386

Acoustic characterization of Mysis relicta  

Microsoft Academic Search

It is possible to increase the sampling resolution and the available information on zooplankton populations by applying acoustic sampling techniques. Knowledge of an organism's acoustic target strength (TS) is critical for translating acoustic data into meaningful biological information, such as numerical abundance. We have taken several approaches to evaluate the acoustic TS of Mysis relicta, a key benthic-pelagic invertebrate in

Gideon Gal; Lars G. Rudstam; Charles H. Greene

1999-01-01

387

The accidental (acoustical) tourist  

NASA Astrophysics Data System (ADS)

The acoustical phenomenon observed at an ancient temple in the Great Ball Court at Chichen Itza was described as ''little short of amazing--an ancient whispering gallery'' by Silvanus G. Morley, leader of the Carnegie Institute's archaeological team that excavated and restored these structures in the 1920s. Since then, many others have experienced the extraordinary acoustics at Chichen Itza and other Maya sites. Despite these reports, archaeologists and acousticians have until recently shown little interest in understanding these phenomena. After experiencing Chichen Itza's remarkable acoustics as a tourist in 1994, the author commenced collecting and disseminating information about acoustical phenomena there and at other Mayan sites, hoping to stimulate interest among archaeologists and acousticians. Were these designs accidental or intentional? If intentional, how was the knowledge obtained? How were acoustical features used? This paper highlights the author's collection of anecdotal reports of mysterious Mayan acoustics (http://http://www.ianlawton.com/pa1.htm), recommended reading for scientists and engineers who wish to pursue this fascinating study. Also recounted are some of the reactions of archaeologists-ranging from curious, helpful, and insightful to humorous and appalling--to outsiders' efforts to bring serious scientific attention to the new field of acoustical archaeology.

Van Kirk, Wayne

2002-11-01

388

The Apolipoprotein-AI Mimetic Peptide L4F at a Modest Dose Does Not Attenuate Weight Gain, Inflammation, or Atherosclerosis in LDLR-Null Mice  

PubMed Central

Objective High density lipoprotein (HDL) cholesterol levels are inversely related to cardiovascular disease risk and associated with a reduced risk of type 2 diabetes. Apolipoprotein A-I (apoA-I; major HDL protein) mimetics have been reported to reduce atherosclerosis and decrease adiposity. This study investigated the effect of L4F mimetic peptide and apoA-I overexpression on weight gain, insulin resistance, and atherosclerosis in an LDL receptor deficient (Ldlr-/-) model fed a high fat high sucrose with cholesterol (HFHSC) diet. Methods Studies in differentiated 3T3-L1 adipocytes tested whether L4F could inhibit palmitate-induced adipocyte inflammation. In vivo studies used male Ldlr-/- mice fed a HFHSC diet for 12 weeks and were injected daily with L4F (100 µg/mouse) subcutaneously during the last 8 weeks. Wild-type and apoA-I overexpressing Ldlr-/- mice were fed HFHSC diet for 16 weeks. Results Neither L4F administration nor apoA-I overexpression affected weight gain, total plasma cholesterol or triglycerides in our studies. While pre-treatment of 3T3-L1 adipocytes with either L4F or HDL abolished palmitate-induced cytokine expression in vitro, L4F treatment did not affect circulating or adipose tissue inflammatory markers in vivo. Neither L4F administration nor apoA-I overexpression affected glucose tolerance. ApoA-I overexpression significantly reduced atherosclerotic lesion size, yet L4F treatment did not affect atherosclerosis. Conclusion Our results suggest that neither L4F (100 µg/day/mouse) nor apoA-I overexpression affects adiposity or insulin resistance in this model. We also were unable to confirm a reduction in atherosclerosis with L4F in our particular model. Further studies on the effect of apoA-I mimetics on atherosclerosis and insulin resistance in a variety of dietary contexts are warranted. PMID:25286043

Averill, Michelle M.; Kim, Eung Ju; Goodspeed, Leela; Wang, Shari; Subramanian, Savitha; Den Hartigh, Laura J.; Tang, Chongren; Ding, Yilei; Reardon, Catherine A.; Getz, Godfrey S.; Chait, Alan

2014-01-01

389

Inhibition of Myo6 gene expression by co?expression of a mutant of transcription factor POU4F3 (BRN?3C) in hair cells.  

PubMed

An eight?base pair (bp) deletion in the Pou4f3 gene in hair cells is associated with DFNA15, a hereditary form of hearing loss. To explore the pathological mechanisms underlying the development of DFNA15, the effect of the mutation in Pou4f3 on the activity of the myosin VI (Myo6) promoter, was investigated. The upstream regulatory sequence of Myo6 (2625 bp), consisting of an 1899 bp upstream sequence and a 727 bp intron 1 sequence, was amplified using polymerase chain reaction and subcloned into the pGL3?Basic vector expressing firefly luciferase. For verification of inserted fragments, plasmids were subjected to restriction analysis and then sequenced. HEK293T human embryonic kidney cells were transiently transfected with renilla luciferase?thymidine kinase vectors expressing Renilla luciferase and the Myo6 promoter?driven firefly luciferase expressing vectors along with pIRES2?enhanced green fluorescent protein (EGFP)?Pou4f3 (expressing wild?type Pou4f3) or pIRES2?EGFP?Pou4f3 (expressing the truncation mutant of Pou4f3). The relative luciferase activities were measured to determine the activity of the Myo6 promoter. The Myo6 promoter activity was not affected by co?expression of wild?type Pou4f3, as indicated by the comparable relative luciferase activities in the presence of the pIRES2?EGFP?Pou4f3 and the empty control vectors. However, co?expression of mutated Pou4f3 significantly inhibited the activity of the Myo6 promoter to almost half of that of the control (P<0.001). The data suggests that mutated Pou4f3 has a negative role in the promoter activity of Myo6, and by extension, the expression of myosin VI, and this may be an underlying mechanism of DFNA15 hearing loss. PMID:24535414

Ma, Deng-Bin; Chen, Jie; Xia, Yang; Zhu, Guang-Jie; Ma, Xiao-Feng; Zhou, Han; Gu, Ya-Jun; Yu, Chen-Jie; Zhu, Min-Sheng; Qian, Xiao-Yun; Gao, Xia

2014-04-01

390

Comparison of Diagnostic Efficacy of Contrast-Enhanced Ultrasound, Acoustic Radiation Force Impulse Imaging, and Their Combined Use in Differentiating Focal Solid Thyroid Nodules  

PubMed Central

Background A key limitation of conventional ultrasound (US) includes poor differentiation of benign from malignant thyroid nodules. Contrast-enhanced US (CEUS) and acoustic radiation force impulse (ARFI) could provide better characterization of focal thyroid nodules; however, no studies have compared their efficacies. Objective To evaluate the diagnostic efficacy of conventional US,CEUS, ARFI, and their combined use in differentiating focal solid thyroid nodules. Methods One-hundred-forty-six Chinese patients with 175 thyroid nodules (119 benign and 56 malignant) were prospectively enrolled. Each patients underwent conventional US, CEUS and ARFI, respectively. The diagnostic performance of the conventional US, CEUS, ARFI, combined use of either CEUS or ARFI and combined use of the three modalities were assessed and compared using Pathological diagnosis (histological/cytological) as the reference method. Results There were no significant differences between individual groups (CEUS vs US, P?=?0.279, ARFI vs US, P?=?0.372, CEUS vs ARFI, P?=?0.849), combined use of US and CEUS or combined use of US and ARFI yielded significant difference compared to US. (combination of US & CEUS vs US, P?=?0.021; combination of US & ARFI vs US, P?=?0.036). The combination of three modalities significantly improved the diagnostic accuracy compared with either combination of conventional US and CEUS or combination of conventional US and ARFI (P?=?0.045 and P ?=?0.027, respectively). Conclusions CEUS and ARFI can be used as an additional tool in the diagnostic work up of thyroid nodules. The combination of CEUS with ARFI can significantly improve the diagnostic accuracy. PMID:24594879

Deng, Jin; Zhou, Ping; Tian, Shuang-ming; Zhang, Lu; Li, Jia-le; Qian, Ying

2014-01-01

391

Underwater acoustic omnidirectional absorber  

NASA Astrophysics Data System (ADS)

Gradient index media, which are designed by varying local element properties in given geometry, have been utilized to manipulate acoustic waves for a variety of devices. This study presents a cylindrical, two-dimensional acoustic "black hole" design that functions as an omnidirectional absorber for underwater applications. The design features a metamaterial shell that focuses acoustic energy into the shell's core. Multiple scattering theory was used to design layers of rubber cylinders with varying filling fractions to produce a linearly graded sound speed profile through the structure. Measured pressure intensity agreed with predicted results over a range of frequencies within the homogenization limit.

Naify, Christina J.; Martin, Theodore P.; Layman, Christopher N.; Nicholas, Michael; Thangawng, Abel L.; Calvo, David C.; Orris, Gregory J.

2014-02-01

392

Acoustic well cleaner  

DOEpatents

A method and apparatus are disclosed for cleaning the wellbore and the near wellbore region. A sonde is provided which is adapted to be lowered into a borehole and which includes a plurality of acoustic transducers arranged around the sonde. Electrical power provided by a cable is converted to acoustic energy. The high intensity acoustic energy directed to the borehole wall and into the near wellbore region, redissolves or resuspends the material which is reducing the permeability of the formation and/or restricting flow in the wellbore.

Maki, Jr., Voldi E. (11904 Bell Ave., Austin, TX 78759-2415); Sharma, Mukul M. (Dept. of Petroleum Engr. Univ. of Texas, Austin, TX 78712)

1997-01-21

393

A new acoustic lens material for large area detectors in photoacoustic breast tomography?  

PubMed Central

Objectives We introduce a new acoustic lens material for photoacoustic tomography (PAT) to improve lateral resolution while possessing excellent acoustic acoustic impedance matching with tissue to minimize lens induced image artifacts. Background A large surface area detector due to its high sensitivity is preferable to detect weak signals in photoacoustic mammography. The lateral resolution is then limited by the narrow acceptance angle of such detectors. Acoustic lenses made of acrylic plastic (PMMA) have been used to enlarge the acceptance angle of such detectors and improve lateral resolution. However, such PMMA lenses introduce image artifacts due to internal reflections of ultrasound within the lenses, the result of acoustic impedance mismatch with the coupling medium or tissue. Methods A new lens is proposed based on the 2-component resin Stycast 1090SI. We characterized the acoustic properties of the proposed lens material in comparison with commonly used PMMA, inspecting the speed of sound, acoustic attenuation and density. We fabricated acoustic lenses based on the new material and PMMA, and studied the effect of the acoustic lenses on detector performance comparing finite element (FEM) simulations and measurements of directional sensitivity, pulse-echo response and frequency response. We further investigated the effect of using the acoustic lenses on the image quality of a photoacoustic breast tomography system using k-Wave simulations and experiments. Results Our acoustic characterization shows that Stycast 1090SI has tissue-like acoustic impedance, high speed of sound and low acoustic attenuation. These acoustic properties ensure an excellent acoustic lens material to minimize the acoustic insertion loss. Both acoustic lenses show significant enlargement of detector acceptance angle and lateral resolution improvement from modeling and experiments. However, the image artifacts induced by the presence of an acoustic lens are reduced using the proposed lens compared to PMMA lens, due to the minimization of internal reflections. Conclusions The proposed Stycast 1090SI acoustic lens improves the lateral resolution of photoacoustic tomography systems while not suffering from internal reflection-induced image artifacts compared a lens made of PMMA.

Xia, Wenfeng; Piras, Daniele; van Hespen, Johan C.G.; Steenbergen, Wiendelt; Manohar, Srirang

2013-01-01

394

Hypersensitivity in the luminescence and 4f-4f absorption properties of mono- and dinuclear EuIII and ErIII complexes based on fluorinated ?-diketone and diimine/ bis-diimine ligands.  

PubMed

The results of our investigation on the sensitized luminescence properties of three Eu(III) ?-diketonate complexes of the form [Eu(2)(fod)(6)(?-bpm)], [Eu(fod)(3)(phen)] and [Eu(fod)(3)(bpy)] and 4f-4f absorption properties of their Er(III) analogues ( fod = anion of 6,6,7,7,8,8,8- heptafluoro-2,2-dimethyl-3,5-octanedione, bpm = 2,2'-bipyrimidine, phen = 1,10-phenanthroline and bpy = 2,2'-bipyridyl) in a series of non-aqueous solvents are presented. The Eu(III) complexes are highly luminescent and their luminescence properties (intensity and band shape) are sensitive to the changes in the inner coordination sphere of the Eu(III) ion. The luminescence intensity of the mononuclear complexes in pyridine is drastically decreased. The coordination structure of the complexes in pyridine is transformed into a more symmetrical one which results into a slow radiative rate of the emission from the complexes. The ancillary ligands, phen and bpy are found better co-sensitizers as compared to the bpm to sensitize Eu(III)-luminescence. The 4f-4f absorption properties (oscillator strength and band shape) of the Er(III) complexes demonstrate that (4)G(11/2) ? (4)I(11/2) and (2)H(11/2) ? (4)I(15/2) hypersensitive transitions of Er(III) are very sensitive in some coordinating solvents which reflects complex-solvent interaction in solution. The hypersensitive transitions of [Er(fod)(3)(phen)] remain unaffected in any of the solvents and this complex retains its bulk composition in solution. The erbium complexes as well as the Er(fod)(3) chelate are invaded by DMSO. This solvent enters the inner coordination sphere by replacing heterocyclic ligand and the complexes acquire similar structure [Er(fod)(3)(DMSO)(2)] in this solvent. The results reveal that the luminescence and absorption properties of lanthanide complexes in solution can be controlled by tuning the coordination structure through ancillary ligands and donor solvents. This work shall prove useful in designing new biological applications with such probes. PMID:20625803

Irfanullah, Mir; Iftikhar, Khalid

2011-01-01

395

Compact acoustic refrigerator  

DOEpatents

A compact acoustic refrigeration system actively cools components, e.g., electrical circuits, in a borehole environment. An acoustic engine includes first thermodynamic elements for generating a standing acoustic wave in a selected medium. An acoustic refrigerator includes second thermodynamic elements located in the standing wave for generating a relatively cold temperature at a first end of the second thermodynamic elements and a relatively hot temperature at a second end of the second thermodynamic elements. A resonator volume cooperates with the first and second thermodynamic elements to support the standing wave. To accommodate the high heat fluxes required for heat transfer to/from the first and second thermodynamic elements, first heat pipes transfer heat from the heat load to the second thermodynamic elements and second heat pipes transfer heat from first and second thermodynamic elements to the borehole environment. 18 figs.

Bennett, G.A.

1992-11-24

396

Compact acoustic refrigerator  

DOEpatents

A compact acoustic refrigeration system actively cools components, e.g., electrical circuits (22), in a borehole environment. An acoustic engine (12, 14) includes first thermodynamic elements (12) for generating a standing acoustic wave in a selected medium. An acoustic refrigerator (16, 26, 28) includes second thermodynamic elements (16) located in the standing wave for generating a relatively cold temperature at a first end of the second thermodynamic elements (16) and a relatively hot temperature at a second end of the second thermodynamic elements (16). A resonator volume (18) cooperates with the first and second thermodynamic elements (12, 16) to support the standing wave. To accommodate the high heat fluxes required for heat transfer to/from the first and second thermodynamic elements (12, 16), first heat pipes (24, 26) transfer heat from the heat load (22) to the second thermodynamic elements (16) and second heat pipes (28, 32) transfer heat from first and second thermodynamic elements (12, 16) to the borehole environment.

Bennett, Gloria A. (Los Alamos, NM)

1992-01-01

397

Space, time and acoustics  

E-print Network

This thesis describes the development of new concepts in acoustical analysis from their inception to implementation as a computer design tool. Research is focused on a computer program which aids the designer to visually ...

Thompson, Philip R. Z. (Philip Reed Zane)

1988-01-01

398

Automatic acoustic guitar tuner  

E-print Network

Acoustic guitar musicians tune their instruments by using a conventional tuner. Individuals pluck the string and the conventional tuner indicates whether the note is sharp or flat. The musician then has to wind the string ...

Bocanegra, Alfredo

2005-01-01

399

Numerical Techniques in Acoustics  

NASA Technical Reports Server (NTRS)

This is the compilation of abstracts of the Numerical Techniques in Acoustics Forum held at the ASME's Winter Annual Meeting. This forum was for informal presentation and information exchange of ongoing acoustic work in finite elements, finite difference, boundary elements and other numerical approaches. As part of this forum, it was intended to allow the participants time to raise questions on unresolved problems and to generate discussions on possible approaches and methods of solution.

Baumeister, K. J. (compiler)

1985-01-01

400

Fiber optic acoustic sensors  

Microsoft Academic Search

The physical principles which provide the basis for fiber-optic acoustic sensors are discussed for both interferometric and microbend sensor designs. The response of the interferometric microphone is examined from 1 Hz to 50 kHz. Experimental results for a microbend-based microphone for low frequency applications are presented. The acoustic response of optical fibers is discussed in relationship to ultrasonic probes and

J. A. Bucaro; J. H. Cole; A. Dandridge; T. G. Giallorenzi; N. Lagakos

1986-01-01

401

Prediction of the dielectric strength for c-C4F8 mixtures with CF4, CO2, N2, O2 and air by Boltzmann equation analysis  

NASA Astrophysics Data System (ADS)

The dielectric strength of c-C4F8, and mixtures of c-C4F8 with CF4, CO2, N2, O2 and air, is studied through solution of the Boltzmann equation. The reduced ionization coefficient α/N and reduced attachment coefficient η/N are calculated, allowing the reduced effective ionization coefficient (α–η)/N and the critical reduced electric field strength (E/N)cr (the reduced electric field for which (α–η)/N = 0), to be determined. A high value of (E/N)cr for an electronegative gas, such as those considered here, indicates good insulating properties. It is found that c-C4F8–N2 and c-C4F8–air have very similar (E/N)cr values, higher than those of the other three mixtures, and superior even to that of pure SF6 for c-C4F8 concentrations above 80%. Comparison of the results obtained for c-C4F8 and c-C4F8–N2 with experimental values from the literature supports the validity of the approach taken here and the parameters used.

Li, Xingwen; Zhao, Hu; Jia, Shenli; Murphy, Anthony B.

2014-10-01

402

International Space Station Acoustics  

NASA Technical Reports Server (NTRS)

The International Space Station (ISS) presents a significant acoustics challenge considering all of the Modules and equipment that make it an on-orbit laboratory workshop and home with long-term crew occupation. This challenge is further complicated by the fact there are numerous and a wide variety suppliers of Station hardware, including International Partners. This paper addresses how ISS acoustics are managed to ensure a safe and habitable environment by establishing requirements, providing oversight and design support, sharing lessons learned and information, testing for hardware compliance, predicting future acoustic levels, and performing on-orbit measurement and monitoring of actual acoustic levels. ISS acoustic requirements are classified by the type of hardware involved, in three categories: Modules; payloads; and Government Furnished Equipment (GFE). Current status of overall ISS acoustics for each of these hardware categories will be discussed. In addition, the following items will be discussed: examples where NASA design support has been used to aid in obtaining compliance; difficulties encountered; and areas of concern.

Goodman, Jerry

2006-01-01

403

Examination of silicon solar cells by means of the Scanning Laser Acoustic Microscope (SLAM)  

SciTech Connect

The Scanning Laser Acoustic Microscope produces images of internal structure in materials. The acoustic microscope is an imaging system based upon acoustic rather than electromagnetic waves. Variations in the elastic propertis are primarily responsible for structure visualized in acoustic micrographs. The instrument used in these investigations is the SONOMICROSCOPE 100 which can be operated at ultrasonic frequencies of from 30 MHz to 500 MHz. The examination of the silicon solar cells was made at 100 MHz. Data are presented in the form of photomicrographs.

Vorres, C.; Yuhas, D.E.

1981-04-01

404

Examination of silicon solar cells by means of the Scanning Laser Acoustic Microscope (SLAM)  

NASA Technical Reports Server (NTRS)

The Scanning Laser Acoustic Microscope produces images of internal structure in materials. The acoustic microscope is an imaging system based upon acoustic rather than electromagnetic waves. Variations in the elastic propertis are primarily responsible for structure visualized in acoustic micrographs. The instrument used in these investigations is the SONOMICROSCOPE 100 which can be operated at ultrasonic frequencies of from 30 MHz to 500 MHz. The examination of the silicon solar cells was made at 100 MHz. Data are presented in the form of photomicrographs.

Vorres, C.; Yuhas, D. E.

1981-01-01

405

Synthesis and crystal chemistry of the Na MSO 4F family ( M = Mg, Fe, Co, Cu, Zn)  

NASA Astrophysics Data System (ADS)

Our work in metal fluorosulphate chemistry, which was triggered by the discovery of the tavorite-phase of LiFeSO 4F, has unveiled many novel Li- and Na-based phases with desirable electrochemical and/or transport properties. Further exploring this rich crystal chemistry, we have synthesized the Na-based magnesium, copper and zinc fluorosulphates, which crystallise in the maxwellite ( tavorite-like framework) structure just as their Fe and Co counterparts, which were previously reported. These phases show ionic conductivities in the range of ˜10 -7 S cm -1 or ˜10 -11 S cm -1 depending upon their synthesis process and no reversible electrochemical activity versus Na.

Reynaud, Marine; Barpanda, Prabeer; Rousse, Gwenaëlle; Chotard, Jean-Noël; Melot, Brent C.; Recham, Nadir; Tarascon, Jean-Marie

2012-01-01

406

Synthesis and characterization of undoped and Mn(II)ions doped Li2CaAl4(PO4)4F4 nanophosphors  

NASA Astrophysics Data System (ADS)

Undoped and Mn(II) ions doped Li2CaAl4(PO4)4F4 have been synthesized by conventional solid state reaction method and characterized by powder X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive spectrum (EDS), transmission electron microscopy (TEM), optical absorption, Electron Paramagnetic Resonance (EPR), Photoluminescence (PL) and FT-IR techniques. The average crystallite sizes of prepared samples were calculated from the XRD data around 31 and 48 nm. SEM and TEM images show rods and irregular shaped particles respectively. Optical absorption spectra exhibit the characteristic absorption bands of Mn(II) ions in distorted octahedral site symmetry. EPR spectrum exhibit resonance signal at g = 2.01. PL spectrum of undoped and Mn(II) ions doped phosphor exhibited emission peaks from blue to red region and corresponding CIE coordinates are also calculated. FT-IR spectrum of prepared samples clearly exhibited the different vibrational bands and assigned to the phosphate ions and water molecules.

Jaya Raja, B.; Rajesh Yadav, M.; Pushpa Manjari, V.; Babu, B.; Rama Krishna, Ch.; Ravikumar, R. V. S. S. N.

2014-11-01

407

Intense green-emitting Sr 2 LiSiO 4 F:Eu 2+ phosphor for n-UV white LEDs  

Microsoft Academic Search

Eu2+-activated Sr2LiSiO4F phosphors were synthesized at 900°C by solid-state reaction in reducing atmosphere, and their photoluminescence (PL) properties\\u000a were systematically investigated by diffuse reflection spectra, PL excitation and emission spectra, and by the fluorescence\\u000a decay curve. Sr2LiSiO4F:Eu2+ emits intense green light at 520 nm originating from the 5d14f6?4f7 transition of Eu2+ under 365 nm n-UV excitation. The PL excitation spectrum

Xinmin Zhang; Jong Su Kim

2009-01-01

408

Millimeter Waves: Acoustic and Electromagnetic  

PubMed Central

This article is the presentation I gave at the D'Arsonval Award Ceremony on June 14, 2011 at the Bioelectromagnetics Society Annual Meeting in Halifax, Nova Scotia. It summarizes my research activities in acoustic and electromagnetic millimeter waves over the past 47 years. My earliest research involved acoustic millimeter waves, with a special interest in diagnostic ultrasound imaging and its safety. For the last 21 years my research expanded to include electromagnetic millimeter waves, with a special interest in the mechanisms underlying millimeter wave therapy. Millimeter wave therapy has been widely used in the former Soviet Union with great reported success for many diseases, but is virtually unknown to Western physicians. I and the very capable members of my laboratory were able to demonstrate that the local exposure of skin to low intensity millimeter waves caused the release of endogenous opioids, and the transport of these agents by blood flow to all parts of the body resulted in pain relief and other beneficial effects. PMID:22926874

Ziskin, Marvin C.

2012-01-01

409

Vestibular Schwannoma (Acoustic Neuroma) and Neurofibromatosis  

MedlinePLUS

... Vestibular Schwannoma (Acoustic Neuroma) and Neurofibromatosis Vestibular Schwannoma (Acoustic Neuroma) and Neurofibromatosis On this page: What is ... get additional information? What is a vestibular schwannoma (acoustic neuroma)? A vestibular schwannoma (also known as acoustic ...

410

Design and synthesis of thiazolo[5,4-f]quinazolines as DYRK1A inhibitors, part I.  

PubMed

The convenient synthesis of a library of novel 6,6,5-tricyclic thiazolo[5,4-f] quinazolines (forty molecules) was achieved mainly under microwave irradiation. Dimroth rearrangement and 4,5-dichloro-1,2,3,-dithiazolium chloride (Appel salt) chemistry were associated for the synthesis of a novel 6-aminobenzo[d]thiazole-2,7-dicarbonitrile (16) a versatile molecular platform for the synthesis of various bioactive derivatives. Kinase inhibition of the final compounds was evaluated on a panel of four Ser/Thr kinases (DYRK1A, CDK5, CK1 and GSK3) chosen for their strong implications in various regulation processes, especially Alzheimer's disease (AD). In view of the results of this preliminary screening, thiazolo[5,4-f]quinazoline scaffolds constitutes a promising source of inspiration for the synthesis of novel bioactive molecules. Among the compounds of this novel chemolibrary, 7i, 8i and 9i inhibited DYRK1A with IC50 values ranging in the double-digit nanomolar range (40, 47 and 50 nM, respectively). PMID:25268714

Foucourt, Alicia; Hédou, Damien; Dubouilh-Benard, Carole; Désiré, Laurent; Casagrande, Anne-Sophie; Leblond, Bertrand; Loäec, Nadège; Meijer, Laurent; Besson, Thierry

2014-01-01

411

Design and Synthesis of Thiazolo[5,4-f]quinazolines as DYRK1A Inhibitors, Part II.  

PubMed

The convenient synthesis of a focused library (forty molecules) of novel 6,6,5-tricyclic thiazolo[5,4-f]quinazolines was realized mainly under microwave irradiation. A novel 6-aminobenzo[d]thiazole-2,7-dicarbonitrile (1) was used as a versatile molecular platform for the synthesis of various derivatives. Kinase inhibition, of the obtained final compounds, was evaluated on a panel of two kinases (DYRK1A/1B) together with some known reference DYRK1A and DYRK1B inhibitors (harmine, TG003, NCGC-00189310 and leucettine L41). Compound IC50 values were obtained and compared. Five of the novel thiazolo[5,4-f]quinazoline derivatives prepared, EHT 5372 (8c), EHT 6840 (8h), EHT 1610 (8i), EHT 9851 (8k) and EHT 3356 (9b) displayed single-digit nanomolar or subnanomolar IC50 values and are among the most potent DYRK1A/1B inhibitors disclosed to date. DYRK1A/1B kinases are known to be involved in the regulation of various molecular pathways associated with oncology, neurodegenerative diseases (such as Alzheimer disease, AD, or other tauopathies), genetic diseases (such as Down Syndrome, DS), as well as diseases involved in abnormal pre-mRNA splicing. The compounds described in this communication constitute a highly potent set of novel molecular probes to evaluate the biology/pharmacology of DYR1A/1B in such diseases. PMID:25264830

Foucourt, Alicia; Hédou, Damien; Dubouilh-Benard, Carole; Girard, Angélique; Taverne, Thierry; Casagrande, Anne-Sophie; Désiré, Laurent; Leblond, Bertrand; Besson, Thierry

2014-01-01

412

Electron Scattering from Plasma Processing Gases: C2F4 and c-C4F8  

NASA Astrophysics Data System (ADS)

Fluorocarbons like C_2F4 and C_4F8 are very common processing gases in the plasma etching of silicon dioxide, which is an important step in the manufacture of semiconductor microelectronics. Understanding the reaction chemistry of these molecules is crucial for achieving production efficiency and stability of the etched surfaces. In order to explain, and model, the complex collision processes in such low temperature plasmas, a good knowledge of the absolute cross sections for these processes is essential. We have measured elastic and inelastic (vibrational excitation) electron scattering from C_2F4 and C_4F8 using a crossed electron-molecule beam apparatus. The experimental results consist of absolute differential, integral and momentum transfer cross sections in the energy range 1.5-20 eV and angular range 10^o-130^o. In order to investigate the role of intermediate negative ions (resonances) in the scattering process we have also measured excitation functions for elastic scattering and vibrational excitation of the ground electronic state of both molecules. These results are compared with recent theoretical calculations and the limited amount of experimental data available in the literature.

Jelisavcic, Milica; Panajotovic, Radmila; Buckman, Stephen

2004-09-01

413