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1

Image processing techniques for acoustic images  

NASA Astrophysics Data System (ADS)

The primary goal of this research is to test the effectiveness of various image processing techniques applied to acoustic images generated in MATLAB. The simulated acoustic images have the same characteristics as those generated by a computer model of a high resolution imaging sonar. Edge detection and segmentation are the two image processing techniques discussed in this study. The two methods tested are a modified version of the Kalman filtering and median filtering.

Murphy, Brian P.

1991-06-01

2

Acoustic subwavelength imaging of subsurface objects with acoustic resonant metalens  

SciTech Connect

Early research into acoustic metamaterials has shown the possibility of achieving subwavelength near-field acoustic imaging. However, a major restriction of acoustic metamaterials is that the imaging objects must be placed in close vicinity of the devices. Here, we present an approach for acoustic imaging of subsurface objects far below the diffraction limit. An acoustic metalens made of holey-structured metamaterials is used to magnify evanescent waves, which can rebuild an image at the central plane. Without changing the physical structure of the metalens, our proposed approach can image objects located at certain distances from the input surface, which provides subsurface signatures of the objects with subwavelength spatial resolution.

Cheng, Ying; Liu, XiaoJun, E-mail: liuxiaojun@nju.edu.cn [Key Laboratory of Modern Acoustics, Nanjing University, Nanjing 210093 (China) [Key Laboratory of Modern Acoustics, Nanjing University, Nanjing 210093 (China); State Key Laboratory of Acoustics, Institute of Acoustics, Chinese Academy of Sciences, Beijing 100190 (China); Zhou, Chen; Wei, Qi; Wu, DaJian [Key Laboratory of Modern Acoustics, Nanjing University, Nanjing 210093 (China)] [Key Laboratory of Modern Acoustics, Nanjing University, Nanjing 210093 (China)

2013-11-25

3

Nanoscale coherent acoustic phonon imaging  

NASA Astrophysics Data System (ADS)

An ultrafast optical pump and probe technique known as picosecond ultrasonics is used to generate and detect coherent acoustic phonon pulses in nanostructured films grown on Si wafers. By detecting the phonons after they have diffracted across a millimeter thick wafer, it is possible to measure the scattered phonons in the acoustic far field. Numerical backpropagation algorithms can then be used in order to reconstruct the object which scattered the acoustic phonon pulses. We describe measurements and simulations of experiments performed on surface and sub-surface nanostructures. Results with ~500 nm image resolution are shown, and plans for improving that resolution by an order of magnitude will be described.

Daly, Brian C.; Klein, Julien; Norris, Theodore B.; Pau, Stanley; Tennant, Donald M.; Taylor, Joseph A.; Bower, John E.

2006-02-01

4

Pulsed magneto-acoustic imaging.  

PubMed

Nanoparticles are attracting considerable interest as contrast agents for many different imaging modalities. Moreover, imaging the events at the cellular and molecular level is possible by using nanoparticles that have the desired targeting moiety. Unfortunately, ultrasound imaging cannot visualize the nano-structures directly due to its limited spatial resolution and contrast. We present a new technique, pulsed magneto-acoustic imaging, capable of imaging magnetic nanoparticles indirectly. In this method, a high-strength pulsed magnetic field is used to induce motion within the magnetically labeled tissue and ultrasound is used to detect internal tissue motion. Experiments on tissue-mimicking phantoms and ex-vivo animal tissues demonstrated a clear contrast between normal and iron-laden samples labeled with 5 nm magnetic nanoparticles. In addition, the sensitivity of this new imaging technique was investigated for different concentrations of magnetic agents. The results of the study suggest that magnetic nanoparticles can be used as contrast agents in pulsed magneto-acoustic imaging. Furthermore, PMA imaging could become an imaging tool capable of visualizing the cellular and molecular composition of deep-lying structures. PMID:19964848

Mehrmohammadi, Mohammad; Oh, Junghwan; Aglyamov, Salavat R; Karpiouk, Andrei B; Emelianov, Stanislav Y

2009-01-01

5

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

6

Acoustic imaging microscope  

DOEpatents

An imaging system includes: an object wavefront source and an optical microscope objective all positioned to direct an object wavefront onto an area of a vibrating subject surface encompassed by a field of view of the microscope objective, and to direct a modulated object wavefront reflected from the encompassed surface area through a photorefractive material; and a reference wavefront source and at least one phase modulator all positioned to direct a reference wavefront through the phase modulator and to direct a modulated reference wavefront from the phase modulator through the photorefractive material to interfere with the modulated object wavefront. The photorefractive material has a composition and a position such that interference of the modulated object wavefront and modulated reference wavefront occurs within the photorefractive material, providing a full-field, real-time image signal of the encompassed surface area.

Deason, Vance A.; Telschow, Kenneth L.

2006-10-17

7

Reflective echo tomographic imaging using acoustic beams  

DOEpatents

An inspection system includes a plurality of acoustic beamformers, where each of the plurality of acoustic beamformers including a plurality of acoustic transmitter elements. The system also includes at least one controller configured for causing each of the plurality of acoustic beamformers to generate an acoustic beam directed to a point in a volume of interest during a first time. Based on a reflected wave intensity detected at a plurality of acoustic receiver elements, an image of the volume of interest can be generated.

Kisner, Roger; Santos-Villalobos, Hector J

2014-11-25

8

Acoustic Daylight: Passive acoustic imaging using ambient noise  

NASA Astrophysics Data System (ADS)

Active and passive sonar are the best methods of exploring the ocean over large distances since the ocean is rather transparent to sound. Ambient noise often decreases the performance of sonar by masking the desired signal. It has been proposed that the ambient noise itself can be used to detect and image targets (Buckingham, et.al., 1996), a technique often called 'Acoustic Daylight'. The ambient noise field is focused into a large number of narrow beams. Targets are detected via the acoustic contrasts between those beams which intersect the target and those that do not. A prototype acoustic daylight system has been constructed to test this concept. The Acoustic Daylight Ocean Noise Imaging System (ADONIS) forms 126 receive-only beams spanning 10o in the horizontal and 8o in the vertical. The -3 dB beamwidth approaches 0.6o at 75 kHz. The noise in each beam is filtered into 16 frequency bins logarithmically spaced over the decade of frequencies 8-80 kHz. The frequency and intensity information from each beam is mapped into a color pixel to form an acoustic image. Two acoustic daylight experiments were conducted in San Diego bay. A wide variety of planar, cylindrical, and spherical targets were detected and imaged at ranges up to 40 m using ambient noise as the sole source of acoustic illumination. Targets constructed from different materials could be discriminated based on differences in the spectral content of the scattered energy. The spatial and temporal characteristics of the ambient noise field were examined over the frequencies 5-100 kHz using a pair of broadband hydrophones synchronized to ADONIS. The character of the high-frequency ambient noise field is found to be primarily dependent on the snapping frequency of local snapping shrimp, which in turn is dependent on the time of day. Knowledge of the ambient noise field is used to explain many of the curious features in the acoustic images.

Epifanio, Chad Lawrence

1997-12-01

9

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

10

Chirp generated acoustic wavefield images  

NASA Astrophysics Data System (ADS)

Guided waves are being considered for structural health monitoring (SHM) applications, and they can also be used to reduce subsequent inspection times once defects are detected. One proposed SHM method is to use an array of permanently attached piezoelectric transducers to generate and receive guided waves between the various transducer pairs. The interrogation can be done on a continuous or periodic basis to assess the health of the structure. Once defects are suspected in the structure, the traditional approach is to disassemble components for conventional nondestructive evaluation (NDE); however, this is an expensive and time consuming process. A less expensive alternative to conventional NDE is to record acoustic wavefield images of guided waves generated from the attached transducers. These images clearly show details of guided waves as they propagate outward from the source, reflect from structural discontinuities and specimen boundaries, and scatter from any damage sites within the structure. However, the recorded waves are typically narrowband to enable effective visualization of echoes that are relatively compact in time. In this paper, we consider wavefield images that are recorded from a chirp excitation, which offers the advantage of high quality broadband data from a single excitation. However, responses are not directly useful because the received echoes are too extended in time. Signals are post-processed to obtain multiple narrowband and broadband responses containing echoes that are more compact in time to enable visualization of guided waves interacting with structural features. This technique is demonstrated on an aluminum plate that contains attached stiffeners and glued-on piezoelectric disc transducers. Wavefield data are recorded using an air-coupled transducer scanned over the plate surface while one of the attached transducers acts as a guided wave source. Waves interacting with the stiffener and the inactive discs are analyzed via broadband and narrowband processing at multiple frequencies.

Michaels, Thomas E.; Michaels, Jennifer E.; Lee, Sang Jun; Chen, Xin

2011-04-01

11

Pulsed-Source Interferometry in Acoustic Imaging  

NASA Technical Reports Server (NTRS)

A combination of pulsed-source interferometry and acoustic diffraction has been proposed for use in imaging subsurface microscopic defects and other features in such diverse objects as integrated-circuit chips, specimens of materials, and mechanical parts. A specimen to be inspected by this technique would be mounted with its bottom side in contact with an acoustic transducer driven by a continuous-wave acoustic signal at a suitable frequency, which could be as low as a megahertz or as high as a few hundred gigahertz. The top side of the specimen would be coupled to an object that would have a flat (when not vibrating) top surface and that would serve as the acoustical analog of an optical medium (in effect, an acoustical "optic").

Shcheglov, Kirill; Gutierrez, Roman; Tang, Tony K.

2003-01-01

12

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

13

Real-time three-dimensional optoacoustic imaging using an acoustic lens system  

NASA Astrophysics Data System (ADS)

In medical optoacoustics (photoacoustics), absorbing structures, such as blood vessels, hidden inside scattering media are illuminated with short laser pulses resulting in the generation of thermoelastic pressure transients. This initial three-dimensional (3D) acoustic pressure distribution, which exactly resembles the absorption distribution, was imaged into a water container with a 4f acoustic lens system. An optical dark-field stereo imaging system using a 30ns flash illumination light was used to capture a snapshot of the pressure-induced refraction index changes in the water container at a predetermined time after the original laser pulse. The imaging system works at 20Hz frame rate and was designed toward a theoretical resolution of 50?m. The proposed method directly provides 3D images of absorbing structures without the need of computational reconstruction algorithms.

Niederhauser, J. J.; Jaeger, M.; Frenz, M.

2004-08-01

14

Quantitative imaging of acoustic reflection and interference  

NASA Astrophysics Data System (ADS)

This paper presents a method for time resolved quantitative imaging of acoustic waves. We present the theoretical background, the experimental method and the comparison between experimental and numerical reconstructions of acoustic reflection and interference. Laser Doppler vibrometry is used to detect the modulation of the propagation velocity of light, c, due to pressure-dependant changes in the refractive index of air. Variation in c is known to be proportional to variation in acoustic pressure and thus can be used to quantify sound pressure fluctuations. The method requires the laser beam to travel through the sound field, in effect integrating pressure along a transect line. We investigate the applicability of the method, in particular the effect of the geometry of the sound radiator on line integration. Both experimental and finite element reconstructions of the sound field are in good agreement, corroborating punctual pressure measurements from a precision microphone. Spatial limitations and accuracy of the method are presented and discussed.

Malkin, Robert; Todd, Thomas; Robert, Daniel

2015-01-01

15

UNIVERSITY OF CALIFORNIA, SAN DIEGO Acoustic Daylight: passive acoustic imaging  

E-print Network

Sources of Noise.......................................................................... 22 2.5 Thermal.3 Acoustic Lens ........................................................................................ 31 3

Buckingham, Michael

16

Ultrasonic liquid crystal-based underwater acoustic imaging  

NASA Astrophysics Data System (ADS)

A new approach to underwater ultrasonic imaging is described and demonstrated which directly converts a 2D acoustic pressure image formed from an acoustic lens into an intensity-mapped visual image. There are no computers nor electronic requirements, nor piezo arrays necessary. The imager relies on the acoustic coupling, which occurs between directed acoustic energy and aligned nematic liquid crystals. The aligned liquid crystal, being optically birefringent, thereby serve as a display when viewed through crossed polarizers. Pressure waves established by acoustic transducers are reflected by the target, focused by an acoustic lens system, and converted into a visible image for target identification in littoral water. Anticipated uses are for searching and identifying underwater mines which are hazardous to military and civilian ships, ferries, and fishing boats. Other uses include search and rescue and inspection of underwater hazards and structures. Acoustic images obtained using only liquid crystal and light are included.

Gerdt, David W.; Baruch, Martin C.; Adkins, Charles M.

1999-03-01

17

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

18

Acoustic Imaging of Snowpack Physical Properties  

NASA Astrophysics Data System (ADS)

Measurements of snowpack depth, density, structure and temperature have often been conducted by the use of snowpits and invasive measurement devices. Previous research has shown that acoustic waves passing through snow are capable of measuring these properties. An experimental observation device (SAS2, System for the Acoustic Sounding of Snow) was used to autonomously send audible sound waves into the top of the snowpack and to receive and process the waves reflected from the interior and bottom of the snowpack. A loudspeaker and microphone array separated by an offset distance was suspended in the air above the surface of the snowpack. Sound waves produced from a loudspeaker as frequency-swept sequences and maximum length sequences were used as source signals. Up to 24 microphones measured the audible signal from the snowpack. The signal-to-noise ratio was compared between sequences in the presence of environmental noise contributed by wind and reflections from vegetation. Beamforming algorithms were used to reject spurious reflections and to compensate for movement of the sensor assembly during the time of data collection. A custom-designed circuit with digital signal processing hardware implemented an inversion algorithm to relate the reflected sound wave data to snowpack physical properties and to create a two-dimensional image of snowpack stratigraphy. The low power consumption circuit was powered by batteries and through WiFi and Bluetooth interfaces enabled the display of processed data on a mobile device. Acoustic observations were logged to an SD card after each measurement. The SAS2 system was deployed at remote field locations in the Rocky Mountains of Alberta, Canada. Acoustic snow properties data was compared with data collected from gravimetric sampling, thermocouple arrays, radiometers and snowpit observations of density, stratigraphy and crystal structure. Aspects for further research and limitations of the acoustic sensing system are also discussed.

Kinar, N. J.; Pomeroy, J. W.

2011-12-01

19

Method and apparatus for acoustic imaging of objects in water  

DOEpatents

A method, system and underwater camera for acoustic imaging of objects in water or other liquids includes an acoustic source for generating an acoustic wavefront for reflecting from a target object as a reflected wavefront. The reflected acoustic wavefront deforms a screen on an acoustic side and correspondingly deforms the opposing optical side of the screen. An optical processing system is optically coupled to the optical side of the screen and converts the deformations on the optical side of the screen into an optical intensity image of the target object.

Deason, Vance A.; Telschow, Kenneth L.

2005-01-25

20

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, Jürgen K.

2014-01-01

21

Imaging of acoustic fields using optical feedback interferometry.  

PubMed

This study introduces optical feedback interferometry as a simple and effective technique for the two-dimensional visualisation of acoustic fields. We present imaging results for several pressure distributions including those for progressive waves, standing waves, as well as the diffraction and interference patterns of the acoustic waves. The proposed solution has the distinct advantage of extreme optical simplicity and robustness thus opening the way to a low cost acoustic field imaging system based on mass produced laser diodes. PMID:25606963

Bertling, Karl; Perchoux, Julien; Taimre, Thomas; Malkin, Robert; Robert, Daniel; Raki?, Aleksandar D; Bosch, Thierry

2014-12-01

22

Quantitative Subsurface Imaging by Acoustic AFM Techniques  

NASA Astrophysics Data System (ADS)

We review the modeling techniques developed for analyzing the effects of 2-D and 3-D subsurface structures on the stiffness measurements by acoustic AFM. Starting from the analytical Hertzian model, we describe important parameters such as penetration depth and subsurface resolution for acoustic AFM imaging. These definitions point to the need for analytical-numerical models based on mechanical surface impedance method and finite element modeling of arbitrary 2-D and 3-D structures buried under the surface. By using the 2-D and 3-D models, the dependence of penetration depth and subsurface resolution on material properties, subsurface structure geometry, and imaging parameters are investigated. It has been shown that high contrast between subsurface structure and substrate increases the detectability of the structure and the visible depth of the structure depends highly on the contact radius. Soft subsurface structures or voids can be detected with appropriate tip radius and force even if they are as deep as 450 nm. However, the sensitivity is higher while detecting stiff structures under thin soft layers. These results can be extrapolated for different applications using the presented guidelines.

Parlak, Zehra; Degertekin, Levent F.

23

Interpreting Underwater Acoustic Images of the Upper Ocean Boundary Layer  

ERIC Educational Resources Information Center

A challenging task in physical studies of the upper ocean using underwater sound is the interpretation of high-resolution acoustic images. This paper covers a number of basic concepts necessary for undergraduate and postgraduate students to identify the most distinctive features of the images, providing a link with the acoustic signatures of…

Ulloa, Marco J.

2007-01-01

24

Transthoracic Cardiac Acoustic Radiation Force Impulse Imaging  

NASA Astrophysics Data System (ADS)

This dissertation investigates the feasibility of a real-time transthoracic Acoustic Radiation Force Impulse (ARFI) imaging system to measure myocardial function non-invasively in clinical setting. Heart failure is an important cardiovascular disease and contributes to the leading cause of death for developed countries. Patients exhibiting heart failure with a low left ventricular ejection fraction (LVEF) can often be identified by clinicians, but patients with preserved LVEF might be undetected if they do not exhibit other signs and symptoms of heart failure. These cases motivate development of transthoracic ARFI imaging to aid the early diagnosis of the structural and functional heart abnormalities leading to heart failure. M-Mode ARFI imaging utilizes ultrasonic radiation force to displace tissue several micrometers in the direction of wave propagation. Conventional ultrasound tracks the response of the tissue to the force. This measurement is repeated rapidly at a location through the cardiac cycle, measuring timing and relative changes in myocardial stiffness. ARFI imaging was previously shown capable of measuring myocardial properties and function via invasive open-chest and intracardiac approaches. The prototype imaging system described in this dissertation is capable of rapid acquisition, processing, and display of ARFI images and shear wave elasticity imaging (SWEI) movies. Also presented is a rigorous safety analysis, including finite element method (FEM) simulations of tissue heating, hydrophone intensity and mechanical index (MI) measurements, and thermocouple transducer face heating measurements. For the pulse sequences used in later animal and clinical studies, results from the safety analysis indicates that transthoracic ARFI imaging can be safely applied at rates and levels realizable on the prototype ARFI imaging system. Preliminary data are presented from in vivo trials studying changes in myocardial stiffness occurring under normal and abnormal heart function. Presented is the first use of transthoracic ARFI imaging in a serial study of heart failure in a porcine model. Results demonstrate the ability of transthoracic ARFI to image cyclically-varying stiffness changes in healthy and infarcted myocardium under good B-mode imaging conditions at depths in the range of 3-5 cm. Challenging imaging scenarios such as deep regions of interest, vigorous lateral motion and stable, reverberant clutter are analyzed and discussed. Results are then presented from the first study of clinical feasibility of transthoracic cardiac ARFI imaging. At the Duke University Medical Center, healthy volunteers and patients having magnetic resonance imaging-confirmed apical infarcts were enrolled for the study. The number of patients who met the inclusion criteria in this preliminary clinical trial was low, but results showed that the limitations seen in animal studies were not overcome by allowing transmit power levels to exceed the FDA mechanical index (MI) limit. The results suggested the primary source of image degradation was clutter rather than lack of radiation force. Additionally, the transthoracic method applied in its present form was not shown capable of tracking propagating ARFI-induced shear waves in the myocardium. Under current instrumentation and processing methods, results of these studies support feasibility for transthoracic ARFI in high-quality B-Mode imaging conditions. Transthoracic ARFI was not shown sensitive to infarct or to tracking heart failure in the presence of clutter and signal decorrelation. This work does provide evidence that transthoracic ARFI imaging is a safe non-invasive tool, but clinical efficacy as a diagnostic tool will need to be addressed by further development to overcome current challenges and increase robustness to sources of image degradation.

Bradway, David Pierson

25

Laser-induced acoustic imaging of underground objects  

NASA Astrophysics Data System (ADS)

This paper introduces a new demining technique based on the photo-acoustic interaction, together with results from photo- acoustic experiments. We have buried different types of targets (metal, rubber and plastic) in different media (sand, soil and water) and imaged them by measuring reflection of acoustic waves generated by irradiation with a CO2 laser. Research has been focused on the signal acquisition and signal processing. A deconvolution method using Wiener filters is utilized in data processing. Using a uniform spatial distribution of laser pulses at the ground's surface, we obtained 3D images of buried objects. The images give us a clear representation of the shapes of the underground objects. The quality of the images depends on the mismatch of acoustic impedance of the buried objects, the bandwidth and center frequency of the acoustic sensors and the selection of filter functions.

Li, Wen; DiMarzio, Charles A.; McKnight, Stephen W.; Sauermann, Gerhard O.; Miller, Eric L.

1999-02-01

26

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

27

Optimization of a biometric system based on acoustic images.  

PubMed

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

28

Far-field image magnification for acoustic waves using anisotropic acoustic metamaterials  

NASA Astrophysics Data System (ADS)

A kind of two-dimensional acoustic metamaterial is designed so that it exhibits strong anisotropy along two orthogonal directions. Based on the rectangular equal frequency contour of this metamaterial, magnifying lenses for acoustic waves, analogous to electromagnetic hyperlenses demonstrated recently in the optical regime, can be realized. Such metamaterial may offer applications in imaging for systems that obey scalar wave equations.

Ao, Xianyu; Chan, C. T.

2008-02-01

29

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

30

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

31

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

32

High-Speed Vortex Wind Velocity Imaging by Acoustic Tomography  

Microsoft Academic Search

\\u000a A technique for monitoring strong vortex wind fields is highly desired due to the rapid development of global warming. Vortex\\u000a wind velocity imaging using an acoustic travel time tomography technique was developed to meet this need. The method can be\\u000a implemented with a small number of parallel facing pairs of acoustic transmitters\\/receivers from just a single illumination\\u000a view direction, so

H. Li; T. Ueki; K. Hayashi; A. Yamada

33

Acoustically modulated x-ray phase contrast imaging.  

PubMed

We report the use of ultrasonic radiation pressure with phase contrast x-ray imaging to give an image proportional to the space derivative of a conventional phase contrast image in the direction of propagation of an ultrasonic beam. Intense ultrasound is used to exert forces on objects within a body giving displacements of the order of tens to hundreds of microns. Subtraction of images made with and without the ultrasound field gives an image that removes low spatial frequency features and highlights high frequency features. The method acts as an acoustic 'contrast agent' for phase contrast x-ray imaging, which in soft tissue acts to highlight small density changes. PMID:15584532

Hamilton, Theron J; Bailat, Claude J; Rose-Petruck, Christoph; Diebold, Gerald J

2004-11-01

34

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

35

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

36

Acoustic Angiography: A New Imaging Modality for Assessing Microvasculature Architecture  

PubMed Central

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

37

Imaging of Acoustic Waves in Piezoelectric Ceramics by Coulomb Coupling  

NASA Astrophysics Data System (ADS)

The transport properties of bulk and guided acoustic waves travelling in a lead zirconate titanate (PZT) disc, originally manufactured to serve as ultrasonic transducer, have been monitored by scanned Coulomb coupling. The images are recorded by excitation and detection of ultrasound with local electric field probes via piezoelectric coupling. A narrow pulse has been used for excitation. Broadband coupling is achieved since neither mechanical nor electrical resonances are involved. The velocities of the traveling acoustic waves determined from the images are compared with characteristic velocities calculated from material properties listed by the manufacturer of the PZT plate.

Habib, Anowarul; Shelke, Amit; Pluta, Mieczyslaw; Kundu, Tribikram; Pietsch, Ullrich; Grill, Wolfgang

2012-07-01

38

Epipolar geometry of opti-acoustic stereo imaging.  

PubMed

Optical and acoustic cameras are suitable imaging systems to inspect underwater structures, both in regular maintenance and security operations. Despite high resolution, optical systems have limited visibility range when deployed in turbid waters. In contrast, the new generation of high-frequency (MHz) acoustic cameras can provide images with enhanced target details in highly turbid waters, though their range is reduced by one to two orders of magnitude compared to traditional low-/midfrequency (10s-100s KHz) sonar systems. It is conceivable that an effective inspection strategy is the deployment of both optical and acoustic cameras on a submersible platform, to enable target imaging in a range of turbidity conditions. Under this scenario and where visibility allows, registration of the images from both cameras arranged in binocular stereo configuration provides valuable scene information that cannot be readily recovered from each sensor alone. We explore and derive the constraint equations for the epipolar geometry and stereo triangulation in utilizing these two sensing modalities with different projection models. Theoretical results supported by computer simulations show that an opti-acoustic stereo imaging system outperforms a traditional binocular vision with optical cameras, particularly for increasing target distance and (or) turbidity. PMID:17699922

Negahdaripour, Shahriar

2007-10-01

39

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

40

A hierarchical variational Bayesian approximation approach in acoustic imaging  

NASA Astrophysics Data System (ADS)

Acoustic imaging is a powerful technique for acoustic source localization and power reconstruction from limited noisy measurements at microphone sensors. But it inevitably confronts a very ill-posed inverse problem which causes unexpected solution uncertainty. Recently, the Bayesian inference methods using sparse priors have been effectively investigated. In this paper, we propose to use a hierarchical variational Bayesian approximation for robust acoustic imaging. And we explore the Student-t priors with heavy tails to enforce source sparsity, and to model non-Gaussian noise respectively. Compared to conventional methods, the proposed approach can achieve the higher spatial resolution and wider dynamic range of source powers for real data from automobile wind tunnel.

Chu, Ning; Mohammad-Djafari, Ali; Gac, Nicolas; Picheral, José

2015-01-01

41

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

42

A fast transform for acoustic imaging with separable arrays  

Microsoft Academic Search

Acoustic imaging is a computationally intensive and ill-conditioned inverse problem, which involves estimating high resolution source distributions with large microphone arrays. In this paper we show how to significantly decrease its computational cost with a fast transform designed for separable array geometries. This transform provides a natural and elegant way of accelerating beamforming, deconvolution methods and regularized least-squares solvers. We

Flávio P. Ribeiro; Vitor H. Nascimento

2011-01-01

43

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

44

Time-resolved gigahertz acoustic wave imaging at arbitrary frequencies.  

PubMed

We describe a way to generate and detect arbitrary frequency components in time-resolved surface acoustic wave imaging based on optical pumping and probing with a periodic light source. The detailed theory of the technique, based on beam modulation and Fourier analysis, for a variety of possible experimental configurations is presented, followed by experimental data for a glass substrate covered with a thin gold film. We show how the acoustic dispersion relation can be obtained to arbitrary frequency resolution, not limited by the laser pulse repetition rate. PMID:25768824

Matsuda, Osamu; Kaneko, Shogo; Wright, Oliver; Tomoda, Motonobu

2015-03-01

45

Acoustic transmission imaging for flow diagnostics  

NASA Astrophysics Data System (ADS)

Wave propagation through a given flow field can be utilized to obtain information about the flow. Acoustic waves in particular offer the possibility of measuring velocity fields, because sound waves are convected with the flow, and temperature fields, because the acoustic index of refraction is a strong function of temperature. This work concentrates on situations where the first effect is dominating compared to the latter one.A sound system capable of "illuminating" a flow field with ultrasonic waves and measuring the amplitude and phase distribution of the transmitted wave as a function of time was constructed. A large area transmitter and a linear receiving array were used as transducers. Parallel signal processing and interleaved data conversion and acquisition result in a maximum frame rate of 10 kHz.The feasibility of measuring velocity disturbances with ultrasound was demonstrated by transmitting sound through a vortex, which was generated in a duct by an airfoil swirl generator. Assuming an exponential fit for the tangential velocity component, inner core radius and circulation can be determined directly from the phase change of the transmitted wave due to the vortex. A more accurate representation of the radial velocity profile can be found by digital reconstruction via the Abel inversion formula, which allows reconstruction of rotationally symmetric objects from line projections. Even though the flow field under investigation was steady, this is neither a restriction of the technique, nor of the apparatus. However, the repetition rate for consecutive data frames depends on the operating procedure.

Trebitz, Bernd Otto

46

A combined parabolic-integral equation approach to the acoustic simulation of vibro-acoustic imaging  

E-print Network

-acoustic imaging A.E. Malcolm a,*, F. Reitich b , J. Yang b , J.F. Greenleaf c , M. Fatemi c a Department of Earth, f1 and f2 (or x1 and x2 for angular frequency), on the region of interest. These two fields then interact nonlinearly to create a force at the difference frequency Dx ¼ x1 � x2 (a few tens of k

Malcolm, Alison

47

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

E-print Network

Mosaicing of acoustic camera images K. Kim, N. Neretti and N. Intrator Abstract: An algorithm, inhomogeneous illumination and low frame rate is presented. Imaging geometry of acoustic cameras. For an acoustic camera, it is shown that, under the same conditions, an affine transformation is a good

Intrator, Nathan

48

Opto-acoustic breast imaging with co-registered ultrasound  

NASA Astrophysics Data System (ADS)

We present results from a recent study involving the ImagioTM breast imaging system, which produces fused real-time two-dimensional color-coded opto-acoustic (OA) images that are co-registered and temporally inter- leaved with real-time gray scale ultrasound using a specialized duplex handheld probe. The use of dual optical wavelengths provides functional blood map images of breast tissue and tumors displayed with high contrast based on total hemoglobin and oxygen saturation of the blood. This provides functional diagnostic information pertaining to tumor metabolism. OA also shows morphologic information about tumor neo-vascularity that is complementary to the morphological information obtained with conventional gray scale ultrasound. This fusion technology conveniently enables real-time analysis of the functional opto-acoustic features of lesions detected by readers familiar with anatomical gray scale ultrasound. We demonstrate co-registered opto-acoustic and ultrasonic images of malignant and benign tumors from a recent clinical study that provide new insight into the function of tumors in-vivo. Results from the Feasibility Study show preliminary evidence that the technology may have the capability to improve characterization of benign and malignant breast masses over conventional diagnostic breast ultrasound alone and to improve overall accuracy of breast mass diagnosis. In particular, OA improved speci city over that of conventional diagnostic ultrasound, which could potentially reduce the number of negative biopsies performed without missing cancers.

Zalev, Jason; Clingman, Bryan; Herzog, Don; Miller, Tom; Stavros, A. Thomas; Oraevsky, Alexander; Kist, Kenneth; Dornbluth, N. Carol; Otto, Pamela

2014-03-01

49

Micromachined Optical and Acoustic Waveguide Systems for Advance Sensing and Imaging Applications  

E-print Network

processes have been developed to enable new micro optical and acoustic waveguide systems for advanced optical sensing and acoustic imaging applications. The investigated applications include non-invasive cancer detection inside human body, in-field soil...

Chang, Cheng-Chung

2014-07-08

50

Near-Field Imaging with Sound: An Acoustic STM Model  

NASA Astrophysics Data System (ADS)

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 considered quantum theory condensed into a pictorial representation. A hands-on model is presented for demonstrating the imaging principles in introductory teaching. It uses sound waves and computer visualization to create mappings of acoustic resonators. The macroscopic simile is made possible by quantum-classical analogies between matter and sound waves. Grounding STM in acoustic experience may help to make the underlying quantum concepts such as tunneling less abstract to students.

Euler, Manfred

2012-10-01

51

Ultra high frequency imaging acoustic microscope  

DOEpatents

An imaging system includes: an object wavefront source and an optical microscope objective all positioned to direct an object wavefront onto an area of a vibrating subject surface encompassed by a field of view of the microscope objective, and to direct a modulated object wavefront reflected from the encompassed surface area through a photorefractive material; and a reference wavefront source and at least one phase modulator all positioned to direct a reference wavefront through the phase modulator and to direct a modulated reference wavefront from the phase modulator through the photorefractive material to interfere with the modulated object wavefront. The photorefractive material has a composition and a position such that interference of the modulated object wavefront and modulated reference wavefront occurs within the photorefractive material, providing a full-field, real-time image signal of the encompassed surface area.

Deason, Vance A.; Telschow, Kenneth L.

2006-05-23

52

Image Processing for AN Amplitude and Phase Acoustic Microscope.  

NASA Astrophysics Data System (ADS)

We have built a scanning acoustic microscope (SAM) operating in the 3 to 10 MHz range that measures both amplitude and phase reliably and accurately. It has been primarily used in non-destructive evaluation (NDE) of machined parts, composite materials, etc. for the presence of cracks, voids, and delaminations. Most SAMs measure amplitude only; by measuring phase as well, we can carry out quantitative NDE and image processing that can not be done with amplitude or phase alone. We have demonstrated several image processing applications that use amplitude and phase measurements; such as transducer characterization, material reflectance function measurements using V(z) inversion, and thin film/delamination thickness measurements. The transverse and depth resolution of the microscope can be enhanced by numerically post processing the digitized images. The enhanced depth resolution has been applied to measuring the profile of deep trenches (2 mm wide by 5 mm deep) designed as scale models of integrated circuit capacitors (2.4 ?m by 6 ?m). This technique could also be applied to a system scaled down in wavelength to characterize ICs. Such a system would use an acoustic microscope operating at higher frequencies or a confocal scanning optical microscope (CSOM) that measures amplitude and phase. Even better depth resolution can be obtained by numerically combining images taken at several different frequencies. The resulting image has a greater range of coverage in the spatial frequency domain in the depth direction than does a single frequency image. This technique could also be implemented in a CSOM using illumination from lasers operating at different wavelengths. The methods has the potential of sharpening the depth response of an optical microscope by a factor of two from what is currently possible. The ability of the acoustic microscope to measure phase allows a novel application for acoustic microscopes: the measurement of capillary waves. Capillary waves are short wavelength ripples on the surface of water. The presence of capillary waves initiates the buildup of larger waves via wind interaction. A measurement of their damping could thus give an indication of weather changes. (Abstract shortened with permission of author.).

Reinholdtsen, Paul Andrew

1989-09-01

53

Acoustic Radiation Force Impulse Imaging of Human Prostates ex vivo  

PubMed Central

It has been challenging for clinicians using current imaging modalities to visualize internal structures and detect lesions inside human prostates. Lack of contrast among prostatic tissues and high false positive or negative detection rates of prostate lesions have limited the use of current imaging modalities in the diagnosis of prostate cancer. In this study, Acoustic Radiation Force Impulse (ARFI) imaging is introduced to visualize the anatomic and abnormal structures in freshly excised human prostates. A modified Siemens Antares™ ultrasound scanner and a Siemens VF10-5 linear array were used to acquire ARFI images. The transducer was attached to a three-dimensional (3D) translation stage, which was programmed to automate volumetric data acquisition. A depth dependent gain (DDG) method was developed and applied to 3D ARFI datasets to compensate for the displacement gradients associated with spatially varying radiation force magnitudes as a function of depth. Nine human prostate specimens were collected and imaged immediately after surgical excision. Prostate anatomical structures such as seminal vesicles, ejaculatory ducts, peripheral zone, central zone, transition zone and verumontanum were visualized with high spatial resolution and in good agreement with McNeal's zonal anatomy. The characteristic appearance of prostate pathologies, such as prostate cancerous lesions, benign prostatic hyperplasia, calcified tissues and atrophy were identified in ARFI images based upon correlation with the corresponding histological slides. This study demonstrates that ARFI imaging can be used to visualize internal structures and detecting suspicious lesions in the prostate and appears promising for image guidance of prostate biopsy. PMID:20350685

Zhai, Liang; Madden, John; Foo, Wen-Chi; Palmeri, Mark L.; Mouraviev, Vladimir; Polascik, Thomas J.; Nightingale, Kathryn R.

2010-01-01

54

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

55

Acoustic Radiation Force Impulse (ARFI) Imaging-Based Needle Visualization  

PubMed Central

Ultrasound-guided needle placement is widely used in the clinical setting, particularly for central venous catheter placement, tissue biopsy and regional anesthesia. Difficulties with ultrasound guidance in these areas often result from steep needle insertion angles and spatial offsets between the imaging plane and the needle. Acoustic Radiation Force Impulse (ARFI) imaging leads to improved needle visualization because it uses a standard diagnostic scanner to perform radiation force based elasticity imaging, creating a displacement map that displays tissue stiffness variations. The needle visualization in ARFI images is independent of needle-insertion angle and also extends needle visibility out of plane. Although ARFI images portray needles well, they often do not contain the usual B-mode landmarks. Therefore, a three-step segmentation algorithm has been developed to identify a needle in an ARFI image and overlay the needle prediction on a coregistered B-mode image. The steps are: (1) contrast enhancement by median filtration and Laplacian operator filtration, (2) noise suppression through displacement estimate correlation coefficient thresholding and (3) smoothing by removal of outliers and best-fit line prediction. The algorithm was applied to data sets from horizontal 18, 21 and 25 gauge needles between 0–4 mm offset in elevation from the transducer imaging plane and to 18G needles on the transducer axis (in plane) between 10° and 35° from the horizontal. Needle tips were visualized within 2 mm of their actual position for both horizontal needle orientations up to 1.5 mm off set in elevation from the transducer imaging plane and on-axis angled needles between 10°–35° above the horizontal orientation. We conclude that segmented ARFI images overlaid on matched B-mode images hold promise for improved needle visibility in many clinical applications. PMID:21608445

Rotemberg, Veronica; Palmeri, Mark; Rosenzweig, Stephen; Grant, Stuart; Macleod, David; Nightingale, Kathryn

2011-01-01

56

Acoustic Radiation Force Impulse (ARFI) imaging-based needle visualization.  

PubMed

Ultrasound-guided needle placement is widely used in the clinical setting, particularly for central venous catheter placement, tissue biopsy and regional anesthesia. Difficulties with ultrasound guidance in these areas often result from steep needle insertion angles and spatial offsets between the imaging plane and the needle. Acoustic Radiation Force Impulse (ARFI) imaging leads to improved needle visualization because it uses a standard diagnostic scanner to perform radiation force based elasticity imaging, creating a displacement map that displays tissue stiffness variations. The needle visualization in ARFI images is independent of needle-insertion angle and also extends needle visibility out of plane. Although ARFI images portray needles well, they often do not contain the usual B-mode landmarks. Therefore, a three-step segmentation algorithm has been developed to identify a needle in an ARFI image and overlay the needle prediction on a coregistered B-mode image. The steps are: (1) contrast enhancement by median filtration and Laplacian operator filtration, (2) noise suppression through displacement estimate correlation coefficient thresholding and (3) smoothing by removal of outliers and best-fit line prediction. The algorithm was applied to data sets from horizontal 18, 21 and 25 gauge needles between 0-4 mm offset in elevation from the transducer imaging plane and to 18G needles on the transducer axis (in plane) between 10 degrees and 35 degrees from the horizontal. Needle tips were visualized within 2 mm of their actual position for both horizontal needle orientations up to 1.5 mm offset in elevation from the transducer imaging plane and on-axis angled needles between 10 degrees-35 degrees above the horizontal orientation. We conclude that segmented ARFI images overlaid on matched B-mode images hold promise for improved needle visibility in many clinical applications. PMID:21608445

Rotemberg, Veronica; Palmeri, Mark; Rosenzweig, Stephen; Grant, Stuart; Macleod, David; Nightingale, Kathryn

2011-01-01

57

An acoustic charge transport imager for high definition television applications  

NASA Technical Reports Server (NTRS)

The primary goal of this research is to develop a solid-state high definition television (HDTV) imager chip operating at a frame rate of about 170 frames/sec at 2 Megapixels per frame. This imager offers an order of magnitude improvement in speed over CCD designs and will allow for monolithic imagers operating from the IR to the UV. The technical approach of the project focuses on the development of the three basic components of the imager and their integration. The imager chip can be divided into three distinct components: (1) image capture via an array of avalanche photodiodes (APD's), (2) charge collection, storage and overflow control via a charge transfer transistor device (CTD), and (3) charge readout via an array of acoustic charge transport (ACT) channels. The use of APD's allows for front end gain at low noise and low operating voltages while the ACT readout enables concomitant high speed and high charge transfer efficiency. Currently work is progressing towards the development of manufacturable designs for each of these component devices. In addition to the development of each of the three distinct components, work towards their integration is also progressing. The component designs are considered not only to meet individual specifications but to provide overall system level performance suitable for HDTV operation upon integration. The ultimate manufacturability and reliability of the chip constrains the design as well. The progress made during this period is described in detail in Sections 2-4.

Hunt, W. D.; Brennan, Kevin F.

1994-01-01

58

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

59

A magnetic resonance imaging-based articulatory and acoustic study of “retroflex” and “bunched” American English ?r?  

PubMed Central

Speakers of rhotic dialects of North American English show a range of different tongue configurations for ?r?. These variants produce acoustic profiles that are indistinguishable for the first three formants [Delattre, P., and Freeman, D. C., (1968). “A dialect study of American English r’s by x-ray motion picture,” Linguistics 44, 28–69; Westbury, J. R. et al. (1998), “Differences among speakers in lingual articulation for American English ?r?,” Speech Commun. 26, 203–206]. It is puzzling why this should be so, given the very different vocal tract configurations involved. In this paper, two subjects whose productions of “retroflex” ?r? and “bunched” ?r? show similar patterns of F1–F3 but very different spacing between F4 and F5 are contrasted. Using finite element analysis and area functions based on magnetic resonance images of the vocal tract for sustained productions, the results of computer vocal tract models are compared to actual speech recordings. In particular, formant-cavity affiliations are explored using formant sensitivity functions and vocal tract simple-tube models. The difference in F4?F5 patterns between the subjects is confirmed for several additional subjects with retroflex and bunched vocal tract configurations. The results suggest that the F4?F5 differences between the variants can be largely explained by differences in whether the long cavity behind the palatal constriction acts as a half- or a quarter-wavelength resonator. PMID:18537397

Zhou, Xinhui; Espy-Wilson, Carol Y.; Boyce, Suzanne; Tiede, Mark; Holland, Christy; Choe, Ann

2008-01-01

60

Using numerical models and volume rendering to interpret acoustic imaging of hydrothermal flow  

Microsoft Academic Search

Our acoustic imaging system will be installed onto the Neptune Canada observatory at the Main Endeavour Field, Juan de Fuca Ridge, which is a Ridge 2000 Integrated Study Site. Thereafter, 16-30 Gb of acoustic imaging data will be collected daily. We are developing a numerical model of merging plumes that will be used to guide expectations and volume rendering software

K. G. Bemis; K. Bennett; J. Takle; P. A. Rona; D. Silver

2009-01-01

61

An acoustic charge transport imager for high definition television applications  

NASA Technical Reports Server (NTRS)

The primary goal of this research is to develop a solid-state television (HDTV) imager chip operating at a frame rate of about 170 frames/sec at 2 Megapixels/frame. This imager will offer an order of magnitude improvements in speed over CCD designs and will allow for monolithic imagers operating from the IR to UV. The technical approach of the project focuses on the development of the three basic components of the imager and their subsequent integration. The camera chip can be divided into three distinct functions: (1) image capture via an array of avalanche photodiodes (APD's); (2) charge collection, storage, and overflow control via a charge transfer transistor device (CTD); and (3) charge readout via an array of acoustic charge transport (ACT) channels. The use of APD's allows for front end gain at low noise and low operating voltages while the ACT readout enables concomitant high speed and high charge transfer efficiency. Currently work is progressing towards the optimization of each of these component devices. In addition to the development of each of the three distinct components, work towards their integration and manufacturability is also progressing. The component designs are considered not only to meet individual specifications but to provide overall system level performance suitable for HDTV operation upon integration. The ultimate manufacturability and reliability of the chip constrains the design as well. The progress made during this period is described in detail.

Hunt, W. D.; Brennan, K. F.; Summers, C. J.

1994-01-01

62

Imaging surface acoustic waves in anisotropic and periodic media  

NASA Astrophysics Data System (ADS)

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 makes this method particularly suited to examining anisotropic materials. The first section of this thesis deals with surface waves on crystals and other homogeneous solids. The general theory describing surface-wave behavior on anisotropic materials is adapted to our technique. In anisotropic materials, two types of surface waves, designated Rayleigh surface waves and pseudo-surface waves, satisfy the boundary conditions for a free surface. The experimental design is then described, and images obtained on a variety of crystalline samples are examined. Discrepancies between the calculations and the observed results have led to an investigation of the effects of fluid loading on the surface waves. It is found that coupling between the surface waves and the loading liquid will attenuate the propagating surface waves, with high frequencies showing stronger attenuation. In addition, the loading will affect the velocities of the surface waves, and in some cases will support additional surface-wave modes. The remainder of the thesis examines surface-wave propagation on a variety of periodic structures. Carbon- fiber/epoxy composites are first examined, and the elastic properties of a homogeneous sample are used to determine the surface-wave velocities of layered samples in the long-wavelength limit. Two systems are then examined in the dispersive regime, where the wavelength of the surface waves is comparable to the periodicity of the sample. The first, a multilayer sample constructed from layers of aluminum and a low-density polymer, has one-dimensional symmetry. Calculations of the acoustic band structure for acoustic waves traveling in this material, and the resulting surface-wave profiles, are compared to the experimental results. Analysis of this sample is complicated by total internal reflection, which occurs at the composite/aluminum interface for a range of propagation directions. The second sample studied is a two-dimensional lattice with hexagonal symmetry. Calculations of surface-wave propagation in this type of sample show that, for certain combinations of materials, a complete acoustic band gap can be obtained. Experiments performed on two samples with this geometry are then compared to the expected surface-wave behavior on these structures.

Vines, Robert Ellsworth

63

Imaging Defects in Thin DLC Coatings Using High Frequency Scanning Acoustic Microscopy  

Microsoft Academic Search

In this work high frequency scanning acoustic microscopy was employed to nondestructively characterize subsurface defects in chromium containing DLC (Cr-DLC) coatings. Subsurface defects as small as one micron were successfully detected in a flat Cr-DLC coated steel coupon. Depth of the imaged subsurface defects was estimated using a simple geometrical acoustics model. The nature of the subsurface defects was investigated

Dong Fei; Douglas A. Rebinsky; Pavel Zinin; Bernd Koehler

2004-01-01

64

Full-Field Imaging of GHz Film Bulk Acoustic Resonator Motion  

SciTech Connect

A full-field view laser ultrasonic imaging method has been developed that measures acoustic motion at a surface without scanning. Images are recorded at normal video frame rates by using dynamic holography with photorefractive interferometric detection. By extending the approach to ultra high frequencies, an acoustic microscope has been developed that is capable of operation at gigahertz frequency and micron length scales. Both acoustic amplitude and phase are recorded, allowing full calibration and determination of phases to within a single arbitrary constant. Results are presented of measurements at frequencies of 800-900 MHz, illustrating a multitude of normal mode behavior in electrically driven thin film acoustic resonators. Coupled with microwave electrical impedance measurements, this imaging mode provides an exceptionally fast method for evaluation of electric-to-acoustic coupling of these devices and their performance. Images of 256 /spl times/ 240 pixels are recorded at 18 fps rates synchronized to obtain both in-phase and quadrature detection of the acoustic motion. Simple averaging provides sensitivity to the subnanometer level at each pixel calibrated over the image using interferometry. Identification of specific acoustic modes and their relationship to electrical impedance characteristics show the advantages and overall high speed of the technique.

Telschow, Kenneth Louis; Deason, Vance Albert; Cottle, David Lynn; Larson III, J. D.

2003-10-01

65

Full-Field Imaging of Acoustic Motion at Nanosecond Time and Micron Length Scales  

SciTech Connect

A full-field view laser ultrasonic imaging method has been developed that measures acoustic motion at a surface without scanning. Images are recorded at normal video frame rates by employing dynamic holography using photorefractive interferometric detection. By extending the approach to ultra high frequencies, an acoustic microscope has been developed capable of operation on the nanosecond time and micron length scales. Both acoustic amplitude and phase are recorded allowing full calibration and determination of phases to within a single arbitrary constant. Results are presented of measurements at frequencies at 800-900 MHz illustrating a multitude of normal mode behavior in electrically driven thin film acoustic resonators. Coupled with microwave electrical impedance measurements, this imaging mode provides an exceptionally fast method for evaluation of electric to acoustic coupling and performance of these devices. Images of 256x240 pixels are recorded at 18Hz rates synchronized to obtain both in-phase and quadrature detection of the acoustic motion. Simple averaging provides sensitivity to the subnanometer level calibrated over the image using interferometry. Identification of specific acoustic modes and their relationship to electrical impedance characteristics show the advantages and overall high speed of the technique.

Telschow, Kenneth Louis; Deason, Vance Albert; Cottle, David Lynn; Larson III, John D.

2002-10-01

66

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

67

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

68

Negative refraction imaging of acoustic metamaterial lens in the supersonic range  

SciTech Connect

Acoustic metamaterials with negative refraction index is the most promising method to overcome the diffraction limit of acoustic imaging to achieve ultrahigh resolution. In this paper, we use localized resonant phononic crystal as the unit cell to construct the acoustic negative refraction lens. Based on the vibration model of the phononic crystal, negative quality parameters of the lens are obtained while excited near the system resonance frequency. Simulation results show that negative refraction of the acoustic lens can be achieved when a sound wave transmiting through the phononic crystal plate. The patterns of the imaging field agree well with that of the incident wave, while the dispersion is very weak. The unit cell size in the simulation is 0.0005 m and the wavelength of the sound source is 0.02 m, from which we show that acoustic signal can be manipulated through structures with dimensions much smaller than the wavelength of incident wave.

Han, Jianning [School of Information and Communication Engineering, North University of China, Taiyuan 030051 (China); Wen, Tingdun [Key Laboratory of Instrumental Science and Dynamic Testing, Ministry of Education, North University of China, Taiyuan 030051 (China); Key Laboratory of Electronic Testing Technology, North University of China, Taiyuan 030051 (China); Yang, Peng; Zhang, Lu [Key Laboratory of Electronic Testing Technology, North University of China, Taiyuan 030051 (China)

2014-05-15

69

ACOUSTICAL IMAGING AND MECHANICAL PROPERTIES OF SOFT ROCK AND MARINE SEDIMENTS  

SciTech Connect

The research during this project has concentrated on developing a correlation between rock deformation mechanisms and their acoustic velocity signature. This has included investigating: (1) the acoustic signature of drained and undrained unconsolidated sands, (2) the acoustic emission signature of deforming high porosity rocks (in comparison to their low porosity high strength counterparts), (3) the effects of deformation on anisotropic elastic and poroelastic moduli, and (4) the acoustic tomographic imaging of damage development in rocks. Each of these four areas involve triaxial experimental testing of weak porous rocks or unconsolidated sand and involves measuring acoustic properties. The research is directed at determining the seismic velocity signature of damaged rocks so that 3-D or 4-D seismic imaging can be utilized to image rock damage. These four areas of study are described in the report: (1) Triaxial compression experiments have been conducted on unconsolidated Oil Creek sand at high confining pressures. (2) Initial experiments on measuring the acoustic emission activity from deforming high porosity Danian chalk were accomplished and these indicate that the AE activity was of a very low amplitude. (3) A series of triaxial compression experiments were conducted to investigate the effects of induced stress on the anisotropy developed in dynamic elastic and poroelastic parameters in rocks. (4) Tomographic acoustic imaging was utilized to image the internal damage in a deforming porous limestone sample. Results indicate that the deformation damage in rocks induced during laboratory experimentation can be imaged tomographically in the laboratory. By extension the results also indicate that 4-D seismic imaging of a reservoir may become a powerful tool for imaging reservoir deformation (including imaging compaction and subsidence) and for imaging zones where drilling operation may encounter hazardous shallow water flows.

Thurman E. Scott, Jr.; Younane Abousleiman

2004-04-01

70

Experimental study on acoustic subwavelength imaging based on zero-mass metamaterials  

NASA Astrophysics Data System (ADS)

Anisotropic zero-mass acoustic metamaterials are able to transmit evanescent waves without decaying to a far distance, and have been used for near-field acoustic subwavelength imaging. In this work, we design and fabricate such metamaterial lens based on clamped paper membrane units. The zero-mass frequency is determined by normal-incidence acoustic transmission measurement. At this frequency, we verify in experiment that the fabricated metamaterial lens is able to distinguish clearly two sound sources separated with a distance 0.16?0 (?0 is the wavelength in air) below the diffraction limit. We also demonstrate that the imaging frequency is invariant to the change of the lens thickness.

Xu, Xianchen; Li, Pei; Zhou, Xiaoming; Hu, Gengkai

2015-01-01

71

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

72

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

73

An Acoustic Charge Transport Imager for High Definition Television  

NASA Technical Reports Server (NTRS)

This project, over its term, included funding to a variety of companies and organizations. In addition to Georgia Tech these included Florida Atlantic University with Dr. William E. Glenn as the P.I., Kodak with Mr. Mike Richardson as the P.I. and M.I.T./Polaroid with Dr. Richard Solomon as the P.I. The focus of the work conducted by these organizations was the development of camera hardware for High Definition Television (HDTV). The focus of the research at Georgia Tech was the development of new semiconductor technology to achieve a next generation solid state imager chip that would operate at a high frame rate (I 70 frames per second), operate at low light levels (via the use of avalanche photodiodes as the detector element) and contain 2 million pixels. The actual cost required to create this new semiconductor technology was probably at least 5 or 6 times the investment made under this program and hence we fell short of achieving this rather grand goal. We did, however, produce a number of spin-off technologies as a result of our efforts. These include, among others, improved avalanche photodiode structures, significant advancement of the state of understanding of ZnO/GaAs structures and significant contributions to the analysis of general GaAs semiconductor devices and the design of Surface Acoustic Wave resonator filters for wireless communication. More of these will be described in the report. The work conducted at the partner sites resulted in the development of 4 prototype HDTV cameras. The HDTV camera developed by Kodak uses the Kodak KAI-2091M high- definition monochrome image sensor. This progressively-scanned charge-coupled device (CCD) can operate at video frame rates and has 9 gm square pixels. The photosensitive area has a 16:9 aspect ratio and is consistent with the "Common Image Format" (CIF). It features an active image area of 1928 horizontal by 1084 vertical pixels and has a 55% fill factor. The camera is designed to operate in continuous mode with an output data rate of 5MHz, which gives a maximum frame rate of 4 frames per second. The MIT/Polaroid group developed two cameras under this program. The cameras have effectively four times the current video spatial resolution and at 60 frames per second are double the normal video frame rate.

Hunt, William D.; Brennan, Kevin; May, Gary; Glenn, William E.; Richardson, Mike; Solomon, Richard

1999-01-01

74

Bubble-based acoustic radiation force elasticity imaging  

Microsoft Academic Search

Acoustic radiation force is applied to bubbles generated by laser-induced optical breakdown (LIOB) to study viscoelastic properties of the surrounding medium. In this investigation, femtosecond laser pulses are focused in the volume of gelatin phantoms of different concentrations to form bubbles. A two-element confocal ultrasonic transducer generates acoustic radiation force on individual bubbles while monitoring their displacement within a viscoelastic

Todd N. Erpelding; K yle W. Hollman; Matthew O'Donnell

2005-01-01

75

Acoustics  

NASA Technical Reports Server (NTRS)

The acoustics environment in space operations is important to maintain at manageable levels so that the crewperson can remain safe, functional, effective, and reasonably comfortable. High acoustic levels can produce temporary or permanent hearing loss, or cause other physiological symptoms such as auditory pain, headaches, discomfort, strain in the vocal cords, or fatigue. Noise is defined as undesirable sound. Excessive noise may result in psychological effects such as irritability, inability to concentrate, decrease in productivity, annoyance, errors in judgment, and distraction. A noisy environment can also result in the inability to sleep, or sleep well. Elevated noise levels can affect the ability to communicate, understand what is being said, hear what is going on in the environment, degrade crew performance and operations, and create habitability concerns. Superfluous noise emissions can also create the inability to hear alarms or other important auditory cues such as an equipment malfunctioning. Recent space flight experience, evaluations of the requirements in crew habitable areas, and lessons learned (Goodman 2003; Allen and Goodman 2003; Pilkinton 2003; Grosveld et al. 2003) show the importance of maintaining an acceptable acoustics environment. This is best accomplished by having a high-quality set of limits/requirements early in the program, the "designing in" of acoustics in the development of hardware and systems, and by monitoring, testing and verifying the levels to ensure that they are acceptable.

Goodman, Jerry R.; Grosveld, Ferdinand

2007-01-01

76

Noise immunity analysis of neuron-like algorithms in acoustic image processing  

SciTech Connect

There exists the problem of pre-selection of the most noise-immune algorithms (including the neuron-like ones) when acoustic signals are processed in subwater acoustic vision systems. A software version is considered for choosing the parameters in the acoustic image processing algorithms which improve the noise immunity of the decision-making process. It is shown that the processing modes with improved noise immunity can be chosen in model experiments associated with threshold changes in the neuron-like transformation algorithms.

Gorsky, S.M.; Kurzenin, E.B.; Khil`ko, A.I.; Yakhno, V.G. [Institute of Physics, Nizhny Novgorod (Russian Federation)

1995-03-01

77

COMPARISON OF ACOUSTIC AND ELECTRICAL IMAGE LOGS FROM THE COSO GEOTHERMAL FIELD, CA  

Microsoft Academic Search

Electrical and acoustic image logs collected from well 58A-10 in crystalline rock on the eastern margin of the Coso Geothermal Field, CA, reveal different populations of planar structures intersecting the borehole. Electrical image logs appear to be sensitive to variations in mineralogy, porosity, and fluid content that highlight both natural fractures and rock fabrics. These fabric elements account for about

NICHOLAS C. DAVATZES; STEVE HICKMAN

78

Acoustic imaging in bat sonar: Echolocation signals and the evolution of echolocation  

Microsoft Academic Search

Echolocating bats behave as though they perceive the crosscorrelation functions between their sonar transmissions and echoes as images of targets, at least with respect to perception of target range, horizontal direction, and shape. These data imply that bats use a multi-dimensional acoustic imaging system for echolocation with broadband, usually frequencymodulated signals. The perceptual structure of the echolocation signals used by

James A. Simmons; Roger A. Stein

1980-01-01

79

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

80

[Specifics of perception of acoustic image of intrinsic bioelectric brain activity].  

PubMed

We studied the particularities of perception of the acoustic image of intrinsic EEG. We found that the assessment of perception of sounds, the presentation of which was synchronized and was agreed with current bioelectric brain activity, is higher that assessment of perception of acoustic EEG image presented in recorded form. Presentation of recorded acoustic image of EEG is accompanied by increased activity of beta-band in the frontal areas, while real-time presentation of acoustic EEG image is accompanied by the increase of slow wave activity: theta- and delta-bands of occipital areas of the brain. Increase activity in theta- and delta-bands of occipital areas in sessions of hearing the acoustic image of EEG in real time depend on the baseline frequency structure of EEG and correlates with expression of alpha-, beta- and theta-bands of bioelectric brain activity in both frontal and occipital areas. We suppose that presentation of sounds synchronized and agreed with the current bioelectric activity, activated the regulatory brain structures. PMID:25665396

Konstantinov, K V; Leonova, M K; Miroshnikov, D B; Klimenko, V M

2014-06-01

81

Image Quality, Tissue Heating, and Frame Rate Trade-offs in Acoustic Radiation Force Impulse Imaging  

PubMed Central

The real-time application of acoustic radiation force impulse (ARFI) imaging requires both short acquisition times for a single ARFI image and repeated acquisition of these frames. Due to the high energy of pulses required to generate appreciable radiation force, however, repeated acquisitions could result in substantial transducer face and tissue heating. We describe and evaluate several novel beam sequencing schemes which, along with parallel-receive acquisition, are designed to reduce acquisition time and heating. These techniques reduce the total number of radiation force impulses needed to generate an image and minimize the time between successive impulses. We present qualitative and quantitative analyses of the trade-offs in image quality resulting from the acquisition schemes. Results indicate that these techniques yield a significant improvement in frame rate with only moderate decreases in image quality. Tissue and transducer face heating resulting from these schemes is assessed through finite element method modeling and thermocouple measurements. Results indicate that heating issues can be mitigated by employing ARFI acquisition sequences that utilize the highest track-to-excitation ratio possible. PMID:19213633

Bouchard, Richard R.; Dahl, Jeremy J.; Hsu, stephen J.; Palmeri, Mark L.; Trahey, Gregg E.

2013-01-01

82

5d-4f and 4f-4f emissions in Ln-doped sesquioxide ceramics  

NASA Astrophysics Data System (ADS)

In this study, various lanthanide and mixed lanthanide oxides (Ln 2O 3 with Ln = La, Lu, Lu 0.5Gd 0.5) powders have been synthesized by a coprecipitation method. The luminescence properties and/or the quenching mechanisms of different dopants (europium, cerium, praseodymium) have been studied. Luminescence mechanisms of Ce:Ln 2O 3 and Pr:Ln 2O 3, are closely related to the 5d and 4f energy levels positions of the dopant versus materials bandgap and crossing effect between dopant energy levels. Energy level positions have been analyzed through optical spectroscopy and their effect on the luminescence is presented. Eu:Lu 2O 3 and Eu:LuGdO 3 have also been prepared as transparent ceramics and radioluminescence properties are presented.

Rétot, H.; Bessière, A.; Viana, B.; LaCourse, B.; Mattmann, E.

2011-05-01

83

Small-aperture acoustic imaging using model-based array signal processing  

NASA Astrophysics Data System (ADS)

Acoustic imaging systems are often used underwater where light is either unavailable or severely attenuated. Acoustic images are typically constructed by transmitting a pulse of acoustic energy into the environment and then striving to resolve the three dimensional spatial origin of received echoes or backscatter. This thesis introduces a new concept for spatially localizing acoustic backscatter called Computed Angle-of-Arrival Transient Imaging (CAATI) that constructs an image by explicitly computing plane wave arrival angles and amplitudes as a function of range from the sonar (i.e. two way travel time after transmit). In contrast to lens or beamformer based imaging methods, the resolution of the new approach is not limited by the physical size of the receive transducer but instead by model uncertainties, and therefore high resolution may be obtained using a small aperture. Plane wave decomposition based on one degree-of-freedom (i.e. a single plane wave is assumed with a time varying amplitude and angle-of-arrival) has for some time been employed by interferometric sidescan sonars to perform 3D imaging of the seafloor using two closely spaced array elements. However, the inability of interferometry to separate multiple concurrent plane wave components has relegated these systems to use in predominantly flat, slowly varying seafloor geometries under conditions of no multipath. CAATI on the other hand extends the number of resolveable concurrent plane wave arrivals to N/2 under coherent signal conditions and N-1 for uncorrelated signal conditions using an N element linear array. The principles underlying the new approach are presented and the factors affecting the validity of the approach under both ideal and non-ideal signal conditions are analyzed and discussed. Alternative array signal processing methods for computing plane wave arrival angles are reviewed and considered in the context of acoustic backscatter imaging. Simulation results are presented in which acoustic backscatter is synthesized for an image phantom (corner reflector) chosen to demonstrate both the viability of the method under non- ideal signal conditions and its advantages over interferometric and beamformed imaging methods. A prototype design for a new seafloor imaging sonar concept called Small Aperture Range vs Angle sonar (SARA) is then described and results are presented for 3D imaging experiments conducted in both a test tank and a lake. The success of CAATI and SARA demonstrates the practical utility of small aperture acoustic imaging using model based array signal processing and opens the door to a new field of imaging research.

Kraeutner, Paul Hans

84

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

85

A surface acoustic wave /SAW/ charge transfer imager  

NASA Technical Reports Server (NTRS)

An 80 MHz, 2-microsecond surface acoustic wave charge transfer device (SAW-CTD) has been fabricated in which surface acoustic waves are used to create traveling longitudinal electric fields in the silicon substrate and to replace the multiphase clocks of charge coupled devices. The traveling electric fields create potential wells which will carry along charges that may be stored in the wells; the charges may be injected into the wells by light. An optical application is proposed where the SAW-CTD structure is used in place of a conventional interline transfer design.

Papanicolauo, N. A.; Lin, H. C.

1981-01-01

86

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

87

Analysis of magnetic resonance imaging acoustic noise generated by a 4.7 T experimental system.  

PubMed

High intensity acoustic noise is an undesirable side-effect in magnetic resonance imaging (MRI) that can cause discomfort and hearing loss in patients and may be an impediment in functional MRI (fMRI) studies of the auditory system. Experimental MRI systems with high magnetic field strengths may generate acoustic noise of higher sound pressure levels (SPLs) than conventional 1.0 and 1.5 T clinical systems. We measured the SPL and spectral content of the acoustic noise generated by the Bruker Biospect 47/40 4.7 T experimental MRI system during scanning sequences commonly used in animal testing. Each sequence generated acoustic noise of high SPL, rapid pulse rates, amplitude-modulated pulse envelopes and multi-peaked spectra. The rapid acquisition with enhancement sequence with a 0.25 mm slice thickness generated SPLs of up to 129 dB peak SPL and 130 dB (A). Fourier analysis of the spectral content of the acoustic noise generated by each MRI sequence showed a wide band of acoustic energy with spectral peaks from 0.2-5 kHz. The intense MRI acoustic impulse noise generated by the 4.7 T system may cause masking of stimuli used in fMRI of the auditory cortex, reduce the hearing acuity of experimental animals and present a risk for unprotected human ears. PMID:11099151

Counter, S A; Olofsson, A; Borg, E; Bjelke, B; Häggström, A; Grahn, H F

2000-09-01

88

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

89

Image Processing for AN Amplitude and Phase Acoustic Microscope  

Microsoft Academic Search

We have built a scanning acoustic microscope (SAM) operating in the 3 to 10 MHz range that measures both amplitude and phase reliably and accurately. It has been primarily used in non-destructive evaluation (NDE) of machined parts, composite materials, etc. for the presence of cracks, voids, and delaminations. Most SAMs measure amplitude only; by measuring phase as well, we can

Paul Andrew Reinholdtsen

1989-01-01

90

The application of acoustic radiation force for molecular imaging and drug delivery  

NASA Astrophysics Data System (ADS)

Acoustic radiation force is exerted on objects in an acoustic field. By optimizing acoustic parameters to maximize this force, ultrasound contrast agents can be manipulated and concentrated with an acoustic field. This technique can be used to enhance molecular imaging and drug delivery. Ultrasonic molecular imaging employs contrast agents such as microbubbles, nanoparticles, or liposomes coated with ligands specific for receptors expressed on cells at sites of angiogenesis, inflammation, or thrombus. Concentration of these highly echogenic contrast agents at a target site enhances the ultrasound signal received from that site, promoting ultrasonic detection and analysis of disease states. It is demonstrated that acoustic radiation force can be used to displace targeted contrast agents to a vessel wall, greatly increasing the number of agents binding to available surface receptors. Radiation force can also be used for microparticle-carrier based drug delivery. Acoustically active drug-carrier vehicles can be concentrated with radiation force, and then disrupted with high-intensity ultrasound bursts, resulting in local delivery of the therapeutic agent. This talk will discuss simulations and experimental results demonstrating these applications.

Dayton, Paul A.; Ferrara, Katherine W.

2005-04-01

91

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

92

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

E-print Network

Ultrasound for Bone Properties; P. Laugier, et al. Scanning Acoustic Microscopy for Micromeasurement of Breast Cancer Using Ultrasonic Echography; I. Akiyama, et al. Ultrasonic Images of Tissue Local Power Spectrum by Means of Wavelet Packets for Prostate Cancer Detection; L. Masotti, et al. Detecting Cardiac

Wagner, Oliver

93

High-frequency acoustic imaging with focused transducer for rapid micro echography of interfaces  

E-print Network

High-frequency acoustic imaging with focused transducer for rapid micro echography of interfaces an important ultrasonic propagation velocity). As demonstrator, we use an assemblage of power modules an ultrasonic generator consisted of a piezoelectric transducer. It converts the electrical signal

Paris-Sud XI, Université de

94

International Symposium on Acoustical Imaging, 19th, Bochum, Germany, April 3-5, 1991  

NASA Astrophysics Data System (ADS)

Papers from the proceedings are presented and cover the following topics: (1) mathematics and physics of acoustical imaging; (2) components and systems; (3) applications in medicine and biology; (4) applications in nondestructive testing; (5) remote sensing; and (6) industrial applications. For individual titles, see A95-90813 through A95-90865.

Ermert, Helmut; Harjes, Hans-Peter

95

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

96

Acoustic investigation of microbubble response to medical imaging ultrasound pulses   

E-print Network

Ultrasound contrast agents have the ability to provide locally increased echogenicity, improving the sensitivity and specificity of images. Due to the unique interaction of microbubbles with the imaging ultrasound field, ...

Thomas, David H.

2010-01-01

97

Passive imaging of cavitational acoustic emissions with ultrasound arrays  

NASA Astrophysics Data System (ADS)

A method is presented for imaging emissions from active microbubbles using an ultrasound array. Since bubble activity plays a role in ultrasound ablation, monitoring cavitation may assist in therapy guidance. This is often achieved by listening passively for bubble emissions with a single-element transducer. Such schemes do not capture the variation in cavitation in form of a two dimensional (2D) map or image. The technique presented here obtains spatial information by creating images solely from the beamformed cavitational-emission energy received by an array, dynamically focused at multiple depths. An analytic expression was derived for these passive images by numerically solving the Rayleigh-Sommerfield integral under the Fresnel approximation. To test accuracy in mapping of localized emissions, a 192-element array was employed to passively image scattering of 520-kHz ultrasound by a 1-mm steel wire. The wire position was estimated from the passive images with rms error 0.9 mm in azimuth and 17.2 mm in range. Bubbles created in air-saturated saline sonicated at 520-kHz were imaged passively from both ultraharmonic and broadband emissions. Good agreement was found between azimuthal brightness distributions of the passive images and B-scan images of the bubble cloud. Broadband emission images from ex vivo bovine liver sonicated with 2.2-MHz focused ultrasound were also recorded. The image brightness along the array azimuth was consistent with the source beam profile. This indicates the possibility of mapping therapeutic ultrasound beams in situ.

Salgaonkar, Vasant A.; Datta, Saurabh; Holland, Christy K.; Mast, T. Douglas

2009-04-01

98

Method and system to synchronize acoustic therapy with ultrasound imaging  

NASA Technical Reports Server (NTRS)

Interference in ultrasound imaging when used in connection with high intensity focused ultrasound (HIFU) is avoided by employing a synchronization signal to control the HIFU signal. Unless the timing of the HIFU transducer is controlled, its output will substantially overwhelm the signal produced by ultrasound imaging system and obscure the image it produces. The synchronization signal employed to control the HIFU transducer is obtained without requiring modification of the ultrasound imaging system. Signals corresponding to scattered ultrasound imaging waves are collected using either the HIFU transducer or a dedicated receiver. A synchronization processor manipulates the scattered ultrasound imaging signals to achieve the synchronization signal, which is then used to control the HIFU bursts so as to substantially reduce or eliminate HIFU interference in the ultrasound image. The synchronization processor can alternatively be implemented using a computing device or an application-specific circuit.

Owen, Neil (Inventor); Bailey, Michael R. (Inventor); Hossack, James (Inventor)

2009-01-01

99

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; Schülein, Florian J. R.; Krenner, Hubert J.; Wixforth, Achim; Salditt, Tim

2014-01-01

100

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

PubMed

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; Schülein, Florian J R; Krenner, Hubert J; Wixforth, Achim; Salditt, Tim

2014-10-01

101

Acoustic Imaging Time Series of Plume Behavior at Grotto Vent, Endeavour Observatory, Juan de Fuca Ridge  

NASA Astrophysics Data System (ADS)

A time series (24 hours) of acoustic images record the behavior of the principal buoyant plume (height interval 0-40 m above seafloor) discharging from black smoker chimneys on the north tower of the Grotto Vent sulfide edifice in the Main Endeavour Vent Field. The plume imaging was performed using the Simrad SM2000 sonar system (frequency 200 kHz) mounted on ROV Jason from a fixed position on the seafloor with a nearly horizontal slant range to the vent of about 20 m at a water depth of about 2190 m. The acoustic imaging is based on Rayleigh backscattering from mineral particles suspended in the plume that are small (microns) relative to the wavelength of the acoustic pulse (centimeter) such that intensity of backscatter is proportional to particle load. The acoustic time series data were acquired on 26-27 July 2000 as part of the VIP (Vent Imaging Pacific) 2000 cruise. We applied our computer visualization and quantification methods to reconstruct the plume 3D volume object and to measure dimensions and orientation. Plume expansion with height corresponds to model prediction (diameter 2 to 20 meters). Particle load decreases with height following model predications. The plume centerline constructed by joining the local center of mass of successive horizontal slices with height through the buoyant plume alternately bends between 0 and 30 degrees to the northeast and southwest in a complex cycle. The plume bending appears to correspond to the regional mixed semidiurnal tidal cycle (H. Mofjeld, personal communication), with a component related to a prevailing northeasterly current (R. Thomson, personal communication). The effectiveness of tracking plume behavior for this short time series shows the potential of the acoustic method for long-term monitoring of the activity and interactions of plumes in seafloor hydrothermal fields.

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

2001-12-01

102

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

103

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

104

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

105

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

106

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, 2 ± 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

107

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

108

Digital image focussing in the near field of a sampled acoustic aperture.  

PubMed

A study has been carried out to investigate digital techniques which can be used to form fully focussed acoustic images. An algebraic approach was used rather than a Fourier technique. Pulse-echo data was digitized from a 2.4 cm long, 32 element, 3 MHz linear array. Water bath tests have demonstrated azimuthal resolution close to beig diffraction limited throughout the field of view. Good images of tissue samples in-vitro have been obtained. Consideration of image sampling requirements and symmetry properties have led to the development of an efficient processing algorithm. PMID:847838

Duck, F; Johnson, S; Greenleaf, J; Samayoa, W

1977-03-01

109

Integrated Software for Image Processing in Radio Frequency Surface and Bulk Acoustic Wave Laser Probe System  

NASA Astrophysics Data System (ADS)

In this paper, we describe the development of an integrated software environment for the image processing of complex data captured using a phase-sensitive surface and bulk acoustic wave (SAW/BAW) laser probe system. The developed software displays the amplitude and phase images of the acquired results and a motion movie of the field pattern. Prior to fast Fourier transform (FFT) and/or inverse FFT (IFFT) operation, we can extract or withdraw specific data in x-y or ?x-?y space by using the mouse on the image. Using the software with a graphical user interface, efficient diagnosis of SAW/BAW devices is made possible.

Wu, Nan; Hashimoto, Ken-ya; Kashiwa, Keisuke; Omori, Tatsuya; Yamaguchi, Masatsune

2009-08-01

110

High performance acoustic three-dimensional image processing system  

SciTech Connect

The reactor vessel of a fast breeder reactor (FBR) is filled with optically opaque liquid sodium, and, therefore, the ultrasonic imaging technique is useful for inspecting in-vessel structures in sodium. The authors have developed a high-speed and high-resolution three-dimensional image processing technique. For imaging in the sodium, a two-dimensional matrix transducer and the M-series transmitting signal were used. The cross correlation processing between the transmitted signal and received signal was used for enhancing the S/N ratio. The image synthesis also attempts the enhancement of resolution by the synthetic aperture focusing technique (SAFT). High-speed processing could be realized by use of parallel processing boards.

Suzuki, T.; Nagai, S.; Maruyama, F. [Toshiba Corp., Yokohama (Japan); Furukawa, H. [JEOL System Technology Co., Ltd., Tokyo (Japan)

1995-08-01

111

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

112

ACOUSTICAL IMAGING AND MECHANICAL PROPERTIES OF SOFT ROCK AND MARINE SEDIMENTS  

SciTech Connect

During this phase of the project the research team concentrated on acquisition of acoustic emission data from the high porosity rock samples. The initial experiments indicated that the acoustic emission activity from high porosity Danian chalk were of a very low amplitude. Even though the sample underwent yielding and significant plastic deformation the sample did not generate significant AE activity. This was somewhat surprising. These initial results call into question the validity of attempting to locate AE activity in this weak rock type. As a result the testing program was slightly altered to include measuring the acoustic emission activity from many of the rock types listed in the research program. The preliminary experimental results indicate that AE activity in the sandstones is much higher than in the carbonate rocks (i.e., the chalks and limestones). This observation may be particularly important for planning microseismic imaging of reservoir rocks in the field environment. The preliminary results suggest that microseismic imaging of reservoir rock from acoustic emission activity generated from matrix deformation (during compaction and subsidence) would be extremely difficult to accomplish.

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

2001-01-31

113

Simulation of Ultrasound in Tomographic Imaging: Theory and Methods Based on Geometrical Acoustics.  

NASA Astrophysics Data System (ADS)

Imaging based upon ultrasound has found extensive application both in medicine for non-invasive diagnosis and in industry for the nondestructive testing of materials. Present commercially available devices are capable of producing images primarily of the geometry of objects (internal shapes and boundaries). A goal for the next generation of ultrasonic imaging devices is the additional capability of depicting, quantitatively, mechanical properties of the tissue or materials under investigation. To achieve this goal, researchers must: (i) identify measurable acoustic parameters capable of characterizing meaningful mechanical properties; and (ii) develop methods for producing quantitative images based upon these parameters. A major stumbling block in quantitative imaging is incomplete understanding of the interaction between imaging methods and the physics of acoustic propagation and measurement. The goal of this thesis is the development of theory and methods for studying this interaction. To study this interaction, methods are developed for simulating the measurements associated with computed ultrasonic transmission tomography based on ultrasonic attenuation. Modern geometrical acoustics theory is applied and novel simulation methods are developed. In conjunction with this, a general theory of discontinuities in partial differential equations is developed. The result is a novel set of rules for transforming first-order linear partial differential equations into corresponding sets of constraints on the surface of the discontinuity. Both the accuracy and the limitations of the method for simulation of measurements of ultrasonic attenuation are demonstrated by comparison with experiment. The simulation is then used to investigate the effects of inhomogeneities on ultrasound measurements. Such results would be difficult to achieve experimentally. Various sources of error in ultrasonic imaging are assessed, and are rank ordered according to their severity. These methods and results are both new and potentially useful in the future development of quantitative ultrasonic imaging based on tissue or materials characterization.

Brandenburger, Gary H.

114

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

115

Quantitative imaging of microvasculature in deep tissue with a spectrum-based photo-acoustic microscopy.  

PubMed

We analyze photo-acoustic signals from capillaries and theoretically demonstrate the quantitative relationship between vascular diameter and spectral slope in a low-frequency band. Phantom experiments validate the theoretical analysis. Based on this finding, spectral slope is proposed as the imaging parameter of a photo-acoustic microscopy. This system effectively quantifies the microvasculature with diameters of 60 and 150 ?m, which are smaller than the wavelength 342 ?m at the central frequency 4.39 MHz of ultrasound transducer. The low frequency also guarantees the imaging depth in the order of centimeters. The proposed scheme could be potential for noninvasive diagnosis of diseases related to abnormal vasoconstriction or angiectasis. PMID:25768159

Gao, Xiaoxiang; Tao, Chao; Wang, Xueding; Liu, Xiaojun

2015-03-15

116

Acoustic radiation force impulse imaging for evaluation of renal parenchyma elasticity in diabetic nephropathy.  

PubMed

OBJECTIVE. The goal of this study is to evaluate the changes in the elasticity of the renal parenchyma in diabetic nephropathy using acoustic radiation force impulse imaging. SUBJECTS AND METHODS. The study included 281 healthy volunteers and 114 patients with diabetic nephropathy. In healthy volunteers, the kidney elasticity was assessed quantitatively by measuring the shear-wave velocity using acoustic radiation force impulse imaging based on age, body mass index, and sex. The changes in the renal elasticity were compared between the different stages of diabetic nephropathy and the healthy control group. RESULTS. In healthy volunteers, there was a statistically significant correlation between the shear-wave velocity values and age and sex. The shear-wave velocity values for the kidneys were 2.87, 3.14, 2.95, 2.68, and 2.55 m/s in patients with stage 1, 2, 3, 4, and 5 diabetic nephropathy, respectively, compared with 2.35 m/s for healthy control subjects. Acoustic radiation force impulse imaging was able to distinguish between the different diabetic nephropathy stages (except for stage 5) in the kidneys. The threshold value for predicting diabetic nephropathy was 2.43 m/s (sensitivity, 84.1%; specificity, 67.3%; positive predictive value, 93.1%; negative predictive value 50.8%; accuracy, 72.1%; positive likelihood ratio, 2.5; and negative likelihood ratio, 0.23). CONCLUSION. Acoustic radiation force impulse imaging could be used for the evaluation of the renal elasticity changes that are due to secondary structural and functional changes in diabetic nephropathy. PMID:25615754

Goya, Cemil; Kilinc, Faruk; Hamidi, Cihad; Yavuz, Alpaslan; Yildirim, Yasar; Cetincakmak, Mehmet Guli; Hattapoglu, Salih

2015-02-01

117

Note: High-speed optical imaging powered by acoustic emission triggering  

NASA Astrophysics Data System (ADS)

Aiming at high speed video recording of rapid events, which occur in loaded solids with unpredictable timing, the efficient triggering method is proposed for optical imaging systems with an aid from the highly sensitive acoustic emission technique. The efficiency of the proposed method is demonstrated on two examples: observation of initiation and propagation of highly localized shear bands in metallic glasses and mechanical twinning in Mg polycrystals.

Seleznev, M.; Vinogradov, A.

2014-07-01

118

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

119

Chapter 0.1 IMAGING AND INVERSION WITH ACOUSTIC AND  

E-print Network

domain to refer to the organization of the data into horizontal distance (offset) versus time. The term.1.2 Mathematical Formulation 3 0.1.3 Inversion Versus Imaging 9 0.1.4 Elastic Full-Waveform Inversion 10 0 that make use of array- based waveform measurements, such as ultrasonics, non-destructive testing, global

Scales, John

120

Synthesis and electrochemical properties of Al-doped LiVPO 4F cathode materials for lithium-ion batteries  

Microsoft Academic Search

Al-doped LiVPO4F cathode materials LiAlxV1-xPO4F were prepared by two-step reactions based on a carbothermal reduction (CTR) process. The properties of the Al-doped LiVPO4F were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), and electrochemical measurements. XRD studies show that the Al-doped LiVPO4F has the same triclinic structure (space group p1) as the undoped LiVPO4F. The SEM images exhibit that

Shengkui ZHONG; Zhoulan YIN; Zhixing WANG; Qiyuan CHEN

2007-01-01

121

Acoustical standards in engineering acoustics  

NASA Astrophysics Data System (ADS)

The Engineering Acoustics Technical Committee is concerned with the evolution and improvement of acoustical techniques and apparatus, and with the promotion of new applications of acoustics. As cited in the Membership Directory and Handbook (2002), the interest areas include transducers and arrays; underwater acoustic systems; acoustical instrumentation and monitoring; applied sonics, promotion of useful effects, information gathering and transmission; audio engineering; acoustic holography and acoustic imaging; acoustic signal processing (equipment and techniques); and ultrasound and infrasound. Evident connections between engineering and standards are needs for calibration, consistent terminology, uniform presentation of data, reference levels, or design targets for product development. Thus for the acoustical engineer standards are both a tool for practices, for communication, and for comparison of his efforts with those of others. Development of many standards depends on knowledge of the way products are put together for the market place and acoustical engineers provide important input to the development of standards. Acoustical engineers and members of the Engineering Acoustics arm of the Society both benefit from and contribute to the Acoustical Standards of the Acoustical Society.

Burkhard, Mahlon D.

2001-05-01

122

Phase-sensitive acoustic imaging and micro-metrology of polymer blend thin films  

NASA Astrophysics Data System (ADS)

Scanning acoustic microscopy with vector contrast (PSAM) at 1.2 GHz is employed for three-dimensional real-space measurements of structure in PS/PMMA (polystyrene/ poly(methyl methacrylate)) blend films, spun-cast on glass and silicon substrates. Processing of the digitized phase and amplitude images yields information on the surface structure and internal structure of the blend films. The complex V(z) functions render qualitative and quantitative material contrast for each image pixel and, hence, permit the characterization of individual domains. It is shown that PSAM can provide valuable insights regarding the polymer blend film morphology and micro-mechanical properties, not acquirable by other ways.

Ngwa, W.; Wannemacher, R.; Grill, W.; Kundu, T.

2003-12-01

123

Contrast-enhanced magneto-photo-acoustic imaging in vivo using dual-contrast nanoparticles?  

PubMed Central

By mapping the distribution of targeted plasmonic nanoparticles (NPs), photoacoustic (PA) imaging offers the potential to detect the pathologies in the early stages. However, optical absorption of the endogenous chromophores in the background tissue significantly reduces the contrast resolution of photoacoustic imaging. Previously, we introduced MPA imaging – a synergistic combination of magneto-motive ultrasound (MMUS) and PA imaging, and demonstrated MPA contrast enhancement using cell culture studies. In the current study, contrast enhancement was investigated in vivo using the magneto-photo-acoustic (MPA) imaging augmented with dual-contrast nanoparticles. Liposomal nanoparticles (LNPs) possessing both optical absorption and magnetic properties were injected into a murine tumor model. First, photoacoustic signals were generated from both the endogenous absorbers in the tissue and the liposomal nanoparticles in the tumor. Then, given significant differences in magnetic properties of tissue and LNPs, the magnetic response of LNPs (i.e. MMUS signal) was utilized to suppress the unwanted PA signals from the background tissue thus improving the PA imaging contrast. In this study, we demonstrated the 3D MPA imaging of LNP-labeled xenografted tumor in a live animal. Compared to conventional PA imaging, the MPA imaging show significantly enhanced contrast between the nanoparticle-labeled tumor and the background tissue. Our results suggest the feasibility of MPA imaging for high contrast in vivo mapping of dual-contrast nanoparticles. PMID:24653976

Qu, Min; Mehrmohammadi, Mohammad; Truby, Ryan; Graf, Iulia; Homan, Kimberly; Emelianov, Stanislav

2014-01-01

124

ACOUSTICAL IMAGING AND MECHANICAL PROPERTIES OF SOFT ROCK AND MARINE SEDIMENTS  

SciTech Connect

During the sixth quarter of this research project the research team developed a method and the experimental procedures for acquiring the data needed for ultrasonic tomography of rock core samples under triaxial stress conditions as outlined in Task 10. Traditional triaxial compression experiments, where compressional and shear wave velocities are measured, provide little or no information about the internal spatial distribution of mechanical damage within the sample. The velocities measured between platen-to-platen or sensor-to-sensor reflects an averaging of all the velocities occurring along that particular raypath across the boundaries of the rock. The research team is attempting to develop and refine a laboratory equivalent of seismic tomography for use on rock samples deformed under triaxial stress conditions. Seismic tomography, utilized for example in crosswell tomography, allows an imaging of the velocities within a discrete zone within the rock. Ultrasonic or acoustic tomography is essentially the extension of that field technology applied to rock samples deforming in the laboratory at high pressures. This report outlines the technical steps and procedures for developing this technology for use on weak, soft chalk samples. Laboratory tests indicate that the chalk samples exhibit major changes in compressional and shear wave velocities during compaction. Since chalk is the rock type responsible for the severe subsidence and compaction in the North Sea it was selected for the first efforts at tomographic imaging of soft rocks. Field evidence from the North Sea suggests that compaction, which has resulted in over 30 feet of subsidence to date, is heterogeneously distributed within the reservoir. The research team will attempt to image this very process in chalk samples. The initial tomographic studies (Scott et al., 1994a,b; 1998) were accomplished on well cemented, competent rocks such as Berea sandstone. The extension of the technology to weaker samples is more difficult but potentially much more rewarding. The chalk, since it is a weak material, also attenuates wave propagation more than other rock types. Three different types of sensors were considered (and tested) for the tomographic imaging project: 600 KHz PZT, 1 MHz PZT, and PVDF film sensors. 600 KHz PZT crystals were selected because they generated a sufficiently high amplitude pulse to propagate across the damaged chalk. A number of different configurations were considered for placement of the acoustic arrays. It was decided after preliminary testing that the most optimum arrangement of the acoustic sensors was to place three arrays of sensors, with each array containing twenty sensors, around the sample. There would be two horizontal arrays to tomographically image two circular cross-sectional planes through the rock core sample. A third array would be vertically oriented to provide a vertical cross-sectional view of the sample. A total of 260 acoustic raypaths would be shot and acquired in the horizontal acoustic array to create each horizontal tomographic image. The sensors can be used as both acoustic sources or as acoustic each of the 10 pulsers to the 10 receivers.

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

2002-11-18

125

Acoustic Image Models for Obstacle Avoidance with Forward-Looking Sonar  

NASA Astrophysics Data System (ADS)

Long-range forward-looking sonars (FLS) have recently been deployed in autonomous unmanned vehicles (AUV). We present models for various features in acoustic images, with the goal of using this sensor for altitude maintenance, obstacle detection and obstacle avoidance. First, we model the backscatter and FLS noise as pixel-based, spatially-varying intensity distributions. Experiments show that these models predict noise with an accuracy of over 98%. Next, the presence of acoustic noise from two other sources including a modem is reliably detected with a template-based filter and a threshold learned from training data. Lastly, the ocean floor location and orientation is estimated with a gradient-descent method using a site-independent template, yielding sufficiently accurate results in 95% of the frames. Temporal information is expected to further improve the performance.

Masek, T.; Kölsch, M.

126

ACOUSTICAL IMAGING AND MECHANICAL PROPERTIES OF SOFT ROCK AND MARINE SEDIMENTS  

SciTech Connect

During the seven quarter of the project the research team analyzed some of the acoustic velocity data and rock deformation data. The goal is to create a series of ''deformation-velocity maps'' which can outline the types of rock deformational mechanisms which can occur at high pressures and then associate those with specific compressional or shear wave velocity signatures. During this quarter, we began to analyze both the acoustical and deformational properties of the various rock types. Some of the preliminary velocity data from the Danian chalk will be presented in this report. This rock type was selected for the initial efforts as it will be used in the tomographic imaging study outlined in Task 10. This is one of the more important rock types in the study as the Danian chalk is thought to represent an excellent analog to the Ekofisk chalk that has caused so many problems in the North Sea. Some of the preliminary acoustic velocity data obtained during this phase of the project indicates that during pore collapse and compaction of this chalk, the acoustic velocities can change by as much as 200 m/s. Theoretically, this significant velocity change should be detectable during repeated successive 3-D seismic images. In addition, research continues with an analysis of the unconsolidated sand samples at high confining pressures obtained in Task 9. The analysis of the results indicate that sands with 10% volume of fines can undergo liquefaction at lower stress conditions than sand samples which do not have fines added. This liquefaction and/or sand flow is similar to ''shallow water'' flows observed during drilling in the offshore Gulf of Mexico.

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

2002-11-18

127

Acoustic Radiation Force Impulse Imaging of Human Prostates: Initial in vivo Demonstration  

PubMed Central

Reliably detecting prostate cancer (PCa) has been a challenge for current imaging modalities. Acoustic radiation force impulse (ARFI) imaging is an elasticity imaging method that uses remotely generated, focused acoustic beams to probe tissue stiffness. A previous study on excised human prostates demonstrated ARFI images portray various prostatic structures and has the potential to guide prostate needle biopsy with improved sampling accuracy. The goal of this study is to demonstrate the feasibility of ARFI imaging to portray internal structures and PCa in the human prostate in vivo. Custom ARFI imaging sequences were designed and implemented using a modified Siemens AntaresTM scanner with a 3D wobbler, end-firing, trans-cavity transducer, EV9F4. 19 patients were consented and imaged immediately preceding surgical prostatectomy. Pathologies and anatomic structures were identified in histological slides by a pathologist blinded to ARFI data, and were then registered with structures found in ARFI images. The results demonstrated that when PCa is visible, it is generally apparent as bilaterally asymmetric stiff structures; benign prostatic hyperplasia (BPH) appears heterogeneous with a nodular texture; the verumontanum and ejaculatory ducts appears softer compared to surrounding tissue, which form a unique 'V' shape; and the boundary of the transitional zone (TZ) forms a stiff rim separating the TZ from the peripheral zone (PZ). These characteristic appearances of prostatic structures are consistent with those found in our previous study of prostate ARFI imaging on excised human prostates. Compared to the matched B-mode images, ARFI images, in general, portray prostate structures with higher contrast. With the end-firing transducer used for this study, ARFI depth penetration was limited to 22mm, and image contrast and resolution were decreased as compared to the previous ex vivo study due to the small transducer aperture size. Even with these limitations, this study suggests ARFI imaging holds promise for guidance of targeted prostate needle biopsy and focal therapy, as well as aiding assessment of changes during watchful waiting/active surveillance. PMID:22104533

Zhai, Liang; Polascik, Thomas J.; Foo, Wen-Chi; Rosenzweig, Stephen; Palmeri, Mark L.; Madden, John; Nightingale, Kathryn R.

2011-01-01

128

Imaging Method for Acoustic Impedance Difference for Puncture Needle-Type Ultrasonography using a Thin Rod with Focusing End Face  

NASA Astrophysics Data System (ADS)

In this paper, we propose an imaging method for acoustic impedance difference for puncture needle-type ultrasonography. The difference in acoustic impedance between benign and malignant tissues will provide valuable diagnostic information. In this experiment, a thin rod that has a concave polished end face was constructed using a fused quartz with a diameter of 1 mm and a focus length of 0.3 mm. An ultrasonic wave emitted from the concave end face of the rod is focused on a tissue. The difference in acoustic impedance was determined by the reflection-type interference-based acoustic impedance measurement method. We confirmed that the image shows the difference in impedance between the polyethylene (PE) plate and acrylic rod with a diameter of 3.5 mm embedded therein. The experimental results show that the method is useful for puncture needle-type ultrasonography.

Yoshizawa, Masasumi; Irie, Takasuke; Itoh, Kouichi; Moriya, Tadashi

2008-05-01

129

Breaking the acoustic diffraction limit via nonlinear effect and thermal confinement for potential deep-tissue high-resolution imaging  

PubMed Central

Our recently developed ultrasound-switchable fluorescence (USF) imaging technique showed that it was feasible to conduct high-resolution fluorescence imaging in a centimeter-deep turbid medium. Because the spatial resolution of this technique highly depends on the ultrasound-induced temperature focal size (UTFS), minimization of UTFS becomes important for further improving the spatial resolution USF technique. In this study, we found that UTFS can be significantly reduced below the diffraction-limited acoustic intensity focal size via nonlinear acoustic effects and thermal confinement by appropriately controlling ultrasound power and exposure time, which can be potentially used for deep-tissue high-resolution imaging. PMID:23479498

Yuan, Baohong; Pei, Yanbo; Kandukuri, Jayanth

2013-01-01

130

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

131

Ultrasound-Stimulated Acoustic Emission in Thermal Image-Guided HIFU Therapy: A Phantom Study  

SciTech Connect

Magnetic resonance image (MRI) is a promising monitoring tool for non-invasive real-time thermal guidance in high intensity focused ultrasound (HIFU) during thermal ablation surgery. However, this approach has two main drawbacks: 1) majority of components need to be redesigned to be MR compatible in order to avoid effecting MR images, and 2) the cost of operating MRI facilities is high. Alternately, ultrasound-stimulated acoustic emission (USAE) method has been applied for detecting thermal variations in tissues. An optical transparent phantom, made from polyacrylamide, containing thermal sensitive indicator protein (Bovine Serum Albumin), was prepared for observing the HIFU-induced denaturalization. A thermal-couple was set up for validation of temperature distribution. Experimental results show that thermal image can be captured clearly under stationary conditions.

Jiang, C. P.; Lin, W. T. [Biomedical Engineering Center, Industrial Technology Research Institute, Hsinchu, Taiwan (China); Chen, W. S. [Department of Physical Medicine and Rehabilitation, National Taiwan University Hospital, Taipei, Taiwan (China)

2006-05-08

132

Acoustic Property Reconstruction of a Neonate Yangtze Finless Porpoise's (Neophocaena asiaeorientalis) Head Based on CT Imaging.  

PubMed

The reconstruction of the acoustic properties of a neonate finless porpoise's head was performed using X-ray computed tomography (CT). The head of the deceased neonate porpoise was also segmented across the body axis and cut into slices. The averaged sound velocity and density were measured, and the Hounsfield units (HU) of the corresponding slices were obtained from computed tomography scanning. A regression analysis was employed to show the linear relationships between the Hounsfield unit and both sound velocity and density of samples. Furthermore, the CT imaging data were used to compare the HU value, sound velocity, density and acoustic characteristic impedance of the main tissues in the porpoise's head. The results showed that the linear relationships between HU and both sound velocity and density were qualitatively consistent with previous studies on Indo-pacific humpback dolphins and Cuvier's beaked whales. However, there was no significant increase of the sound velocity and acoustic impedance from the inner core to the outer layer in this neonate finless porpoise's melon. PMID:25856588

Wei, Chong; Wang, Zhitao; Song, Zhongchang; Wang, Kexiong; Wang, Ding; Au, Whitlow W L; Zhang, Yu

2015-01-01

133

Acoustic Property Reconstruction of a Neonate Yangtze Finless Porpoise's (Neophocaena asiaeorientalis) Head Based on CT Imaging  

PubMed Central

The reconstruction of the acoustic properties of a neonate finless porpoise’s head was performed using X-ray computed tomography (CT). The head of the deceased neonate porpoise was also segmented across the body axis and cut into slices. The averaged sound velocity and density were measured, and the Hounsfield units (HU) of the corresponding slices were obtained from computed tomography scanning. A regression analysis was employed to show the linear relationships between the Hounsfield unit and both sound velocity and density of samples. Furthermore, the CT imaging data were used to compare the HU value, sound velocity, density and acoustic characteristic impedance of the main tissues in the porpoise’s head. The results showed that the linear relationships between HU and both sound velocity and density were qualitatively consistent with previous studies on Indo-pacific humpback dolphins and Cuvier’s beaked whales. However, there was no significant increase of the sound velocity and acoustic impedance from the inner core to the outer layer in this neonate finless porpoise’s melon. PMID:25856588

Wei, Chong; Wang, Zhitao; Song, Zhongchang; Wang, Kexiong; Wang, Ding; Au, Whitlow W. L.; Zhang, Yu

2015-01-01

134

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

135

Large domain, low-contrast acoustic inverse scattering for ultrasound breast imaging.  

PubMed

We present a full-wave acoustic inverse scattering algorithm designed specifically for ultrasonic breast imaging. At ultrasonic frequencies, the image domain is roughly tens to hundreds of min cubed, where min is the smallest wavelength in the transmit signal spectrum. The expected range of contrasts for the breast imaging problem for density, compressibility, and compressive loss is ± 20% of the background. Because of the low contrast, Born iterations provide the basic structure of the inverse scattering algorithm. However, we use a multi-objective covariance-based least squares cost function in place of the basic least squares cost function to estimate the contrast functions. This cost function provides physically meaningful regularization based on a priori knowledge of the contrasts. Also, due to the size of the imaging domain and because the objects to be imaged are low contrast and inhomogeneous, we use the Neumann series solution as the forward solver. The largest domain imaged in simulation was 50 min x 50 min in 2D. PMID:20639168

Haynes, Mark; Moghaddam, Mahta

2010-11-01

136

Improving the resolution of three-dimensional acoustic imaging with planar phased arrays  

NASA Astrophysics Data System (ADS)

This paper examines and compares two methods of improving the quality of three-dimensional beamforming with phased microphone arrays. The intended application is the detection of aerodynamic noise sources on wind turbines. Both methods employ Fourier based deconvolution. The first method involves a transformation of coordinates that tends to make the response to a point source, the point spread function, more shift invariant. The result is a significant improvement in sound source imaging in the transformed coordinate system. However, the inverse transformation to Cartesian coordinates introduces range dependent resolution limitations because of the irregular distribution of the focal points. The second method combines the transformation of coordinates with an alternative scanning technique. This method can be used in near field three-dimensional acoustic imaging to produce maps free of sidelobes and with constant resolution. The robustness of the proposed methods is validated both with computer simulations and experimentally.

Xenaki, Angeliki; Jacobsen, Finn; Fernandez-Grande, Efren

2012-04-01

137

Optical-resolution photoacoustic imaging through thick tissue with a thin capillary as a dual optical-in acoustic-out waveguide  

NASA Astrophysics Data System (ADS)

We demonstrate the ability to guide high-frequency photoacoustic waves through thick tissue with a water-filled silica-capillary (150 ?m inner diameter and 30 mm long). An optical-resolution photoacoustic image of a 30 ?m diameter absorbing nylon thread was obtained by guiding the acoustic waves in the capillary through a 3 cm thick fat layer. The transmission loss through the capillary was about -20 dB, much lower than the -120 dB acoustic attenuation through the fat layer. The overwhelming acoustic attenuation of high-frequency acoustic waves by biological tissue can therefore be avoided by the use of a small footprint capillary acoustic waveguide for remote detection. We finally demonstrate that the capillary can be used as a dual optical-in acoustic-out waveguide, paving the way for the development of minimally invasive optical-resolution photoacoustic endoscopes free of any acoustic or optical elements at their imaging tip.

Simandoux, Olivier; Stasio, Nicolino; Gateau, Jérome; Huignard, Jean-Pierre; Moser, Christophe; Psaltis, Demetri; Bossy, Emmanuel

2015-03-01

138

Optical-resolution photoacoustic imaging through thick tissue with a thin capillary as a dual optical-in acoustic-out waveguide  

E-print Network

We demonstrate the ability to guide high-frequency photoacoustic waves through thick tissue with a water-filled silica-capillary (150 \\mu m inner diameter and 30 mm long). An optical-resolution photoacoustic image of a 30 \\mu m diameter absorbing nylon thread was obtained by guiding the acoustic waves in the capillary through a 3 cm thick fat layer. The transmission loss through the capillary was about -20 dB, much lower than the -120 dB acoustic attenuation through the fat layer. The overwhelming acoustic attenuation of high-frequency acoustic waves by biological tissue can therefore be avoided by the use of a small footprint capillary acoustic waveguide for remote detection. We finally demonstrate that the capillary can be used as a dual optical-in acoustic-out waveguide, paving the way for the development of minimally invasive optical-resolution photoacoustic endoscopes free of any acoustic or optical elements at their imaging tip.

Simandoux, Olivier; Gateau, Jerome; Huignard, Jean-Pierre; Moser, Christophe; Psaltis, Demetri; Bossy, Emmanuel

2015-01-01

139

Bulk video imaging based multivariate image analysis, process control chart and acoustic signal assisted nucleation detection  

Microsoft Academic Search

This article investigates monitoring technologies, which provide systematic solutions for nucleation detection based on external bulk video imaging (BVI). The methods under investigation rely on multivariate image analysis, image feature descriptors and statistical control charts (SPCs). For the design of SPCs the video information is transformed into time series. The application of SPCs may be hindered by autocorrelated time series,

Levente L. Simon; Kaoutar Abbou Oucherif; Zoltan K. Nagy; Konrad Hungerbuhler

2010-01-01

140

Design factors of intravascular dual frequency transducers for super-harmonic contrast imaging and acoustic angiography.  

PubMed

Imaging of coronary vasa vasorum may lead to assessment of the vulnerable plaque development in diagnosis of atherosclerosis diseases. Dual frequency transducers capable of detection of microbubble super-harmonics have shown promise as a new contrast-enhanced intravascular ultrasound (CE-IVUS) platform with the capability of vasa vasorum imaging. Contrast-to-tissue ratio (CTR) in CE-IVUS imaging can be closely associated with low frequency transmitter performance. In this paper, transducer designs encompassing different transducer layouts, transmitting frequencies, and transducer materials are compared for optimization of imaging performance. In the layout selection, the stacked configuration showed superior super-harmonic imaging compared with the interleaved configuration. In the transmitter frequency selection, a decrease in frequency from 6.5?MHz to 5?MHz resulted in an increase of CTR from 15?dB to 22?dB when receiving frequency was kept constant at 30?MHz. In the material selection, the dual frequency transducer with the lead magnesium niobate-lead titanate (PMN-PT) 1-3 composite transmitter yielded higher axial resolution compared to single crystal transmitters (70??m compared to 150??m pulse length). These comparisons provide guidelines for the design of intravascular acoustic angiography transducers. PMID:25856384

Ma, Jianguo; Martin, K Heath; Li, Yang; Dayton, Paul A; Shung, K Kirk; Zhou, Qifa; Jiang, Xiaoning

2015-05-01

141

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

142

ACOUSTICAL IMAGING AND MECHANICAL PROPERTIES OF SOFT ROCK AND MARINE SEDIMENTS  

SciTech Connect

The oil and gas industry has encountered significant problems in the production of oil and gas from weak rocks (such as chalks and limestones) and from unconsolidated sand formations. Problems include subsidence, compaction, sand production, and catastrophic shallow water sand flows during deep water drilling. Together these cost the petroleum industry hundreds of millions of dollars annually. The goals of this first quarterly report is to document the progress on the project to provide data on the acoustic imaging and mechanical properties of soft rock and marine sediments. The project is intended to determine the geophysical (acoustic velocities) rock properties of weak, poorly cemented rocks and unconsolidated sands. In some cases these weak formations can create problems for reservoir engineers. For example, it cost Phillips Petroleum 1 billion dollars to repair of offshore production facilities damaged during the unexpected subsidence and compaction of the Ekofisk Field in the North Sea (Sulak 1991). Another example is the problem of shallow water flows (SWF) occurring in sands just below the seafloor encountered during deep water drilling operations. In these cases the unconsolidated sands uncontrollably flow up around the annulus of the borehole resulting in loss of the drill casing. The $150 million dollar loss of the Ursa development project in the U.S. Gulf Coast resulted from an uncontrolled SWF (Furlow 1998a,b; 1999a,b). The first three tasks outlined in the work plan are: (1) obtain rock samples, (2) construct new acoustic platens, (3) calibrate and test the equipment. These have been completed as scheduled. Rock Mechanics Institute researchers at the University of Oklahoma have obtained eight different types of samples for the experimental program. These include: (a) Danian Chalk, (b) Cordoba Cream Limestone, (c) Indiana Limestone, (d) Ekofisk Chalk, (e) Oil Creek Sandstone, (f) unconsolidated Oil Creek sand, and (g) unconsolidated Brazos river sand. These weak rocks and sands are intended to represent analogs to the formations that present oil and gas engineers with problems during oil and gas production and drilling operations. A series of new axial acoustic sensors have been constructed (and tested) to allow measurement of compressional and shear wave velocities during high pressure triaxial tests on these weak rock and sand samples. In addition, equipment to be utilized over the next 18 months of the project have tested and calibrated. These include the load frames, triaxial pressure cells, pressure sensors, load cells, extensometers, and oscilloscopes have been calibrated and tested. The multichannel acoustic emission and acoustic pulse transmission systems have also been tested. Graduate research assistant, research faculty, and the laboratory technician have begun Tasks 4 and 5 which involve preparing the sand samples and rock samples for testing. The construction of the lateral acoustic sensors has also been started during this quarter as outlined in the project timeline. With the equipment having been tested and calibrated, and the samples now being prepared, the experiments are on schedule to be started in April, 2001.

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

2001-04-01

143

Ultrasonic imaging system using a leaky surface acoustic wave transducer composed of piezoelectric ceramic and fused quartz  

NASA Astrophysics Data System (ADS)

An ultrasonic imaging system is described by using a leaky surface acoustic wave (SAW) transducer composed of a piezoelectric ceramic thin plate/interdigital transducer/fused quartz. It is shown, both numerically and experimentally, that three operation modes of the transducer at a water-solid interface are available. Each of the three modes has a different operation frequency range, corresponding to the leaky SAW velocity. The bulk wave in water as an acoustical coupler between the tansducer and a tested object has a frequency-dependent angle relation; therefore, the acoustic beam steering is easily controlled and flexible in design. The reflection type of C-mode ultrasonic imaging results are demonstrated and are promising for nondestructive testing.

Toda, Kohji; Sawaguchi, Akihiro

1991-01-01

144

A method for the frequency control in time-resolved two-dimensional gigahertz surface acoustic wave imaging  

SciTech Connect

We describe an extension of the time-resolved two-dimensional gigahertz surface acoustic wave imaging based on the optical pump-probe technique with periodic light source at a fixed repetition frequency. Usually such imaging measurement may generate and detect acoustic waves with their frequencies only at or near the integer multiples of the repetition frequency. Here we propose a method which utilizes the amplitude modulation of the excitation pulse train to modify the generation frequency free from the mentioned limitation, and allows for the first time the discrimination of the resulted upper- and lower-side-band frequency components in the detection. The validity of the method is demonstrated in a simple measurement on an isotropic glass plate covered by a metal thin film to extract the dispersion curves of the surface acoustic waves.

Kaneko, Shogo; Tomoda, Motonobu; Matsuda, Osamu, E-mail: omatsuda@eng.hokudai.ac.jp [Division of Applied Physics, Faculty of Engineering, Hokkaido University, Sapporo, Hokkaido 060-8628 (Japan)] [Division of Applied Physics, Faculty of Engineering, Hokkaido University, Sapporo, Hokkaido 060-8628 (Japan)

2014-01-15

145

Imaging of human tooth using ultrasound based chirp-coded nonlinear time reversal acoustics.  

PubMed

Human tooth imaging sonography is investigated experimentally with an acousto-optic noncoupling set-up based on the chirp-coded nonlinear time reversal acoustic concept. The complexity of the tooth internal structure (enamel-dentine interface, cracks between internal tubules) is analyzed by adapting the nonlinear elastic wave spectroscopy (NEWS) with the objective of the tomography of damage. Optimization of excitations using intrinsic symmetries, such as time reversal (TR) invariance, reciprocity, correlation properties are then proposed and implemented experimentally. The proposed medical application of this TR-NEWS approach is implemented on a third molar human tooth and constitutes an alternative of noncoupling echodentography techniques. A 10 MHz bandwidth ultrasonic instrumentation has been developed including a laser vibrometer and a 20 MHz contact piezoelectric transducer. The calibrated chirp-coded TR-NEWS imaging of the tooth is obtained using symmetrized excitations, pre- and post-signal processing, and the highly sensitive 14 bit resolution TR-NEWS instrumentation previously calibrated. Nonlinear signature coming from the symmetry properties is observed experimentally in the tooth using this bi-modal TR-NEWS imaging after and before the focusing induced by the time-compression process. The TR-NEWS polar B-scan of the tooth is described and suggested as a potential application for modern echodentography. It constitutes the basis of the self-consistent harmonic imaging sonography for monitoring cracks propagation in the dentine, responsible of human tooth structural health. PMID:21371732

Dos Santos, Serge; Prevorovsky, Zdenek

2011-08-01

146

SIMULTANEOUS BILATERAL REAL-TIME 3-D TRANSCRANIAL ULTRASOUND IMAGING AT 1 MHZ THROUGH POOR ACOUSTIC WINDOWS  

PubMed Central

Ultrasound imaging has been proposed as a rapid, portable alternative imaging modality to examine stroke patients in pre-hospital or emergency room settings. However, in performing transcranial ultrasound examinations, 8%–29% of patients in a general population may present with window failure, in which case it is not possible to acquire clinically useful sonographic information through the temporal bone acoustic window. In this work, we describe the technical considerations, design and fabrication of low-frequency (1.2 MHz), large aperture (25.3 mm) sparse matrix array transducers for 3-D imaging in the event of window failure. These transducers are integrated into a system for real-time 3-D bilateral transcranial imaging—the ultrasound brain helmet—and color flow imaging capabilities at 1.2 MHz are directly compared with arrays operating at 1.8 MHz in a flow phantom with attenuation comparable to the in vivo case. Contrast-enhanced imaging allowed visualization of arteries of the Circle of Willis in 5 of 5 subjects and 8 of 10 sides of the head despite probe placement outside of the acoustic window. Results suggest that this type of transducer may allow acquisition of useful images either in individuals with poor windows or outside of the temporal acoustic window in the field. PMID:23415287

Lindsey, Brooks D.; Nicoletto, Heather A.; Bennett, Ellen R.; Laskowitz, Daniel T.; Smith, Stephen W.

2013-01-01

147

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

148

Acoustic attenuation compensation in photoacoustic tomography: application to high-resolution 3D imaging of vascular networks in mice  

NASA Astrophysics Data System (ADS)

The reconstruction algorithms commonly used in photoacoustic tomography do not account for the effects of acoustic attenuation on the measured time-domain signals. For experimental measurements made in biological tissue, acoustic attenuation causes the high frequency components of the generated ultrasound signals to be significantly reduced. When this signal loss is neglected, it manifests as a depth dependent magnitude error and blurring of features within the reconstructed photoacoustic image. Here, the approach described by Treeby et al. [Inverse Problems 26(11), p. 115003, 2010] is applied to the reconstruction of high-resolution threedimensional photoacoustic images of vascular networks around the abdomen of a pregnant female mouse. The reconstruction is based on the idea of time reversal in which a numerical model of the acoustic forward problem is run backwards in time. Compensation of acoustic attenuation in the inverse problem is achieved by using a forward model that accurately accounts for the frequency dependent attenuation experimentally observed in biological tissue. The regularisation of the inverse problem is discussed, and the methodology demonstrated through the reconstruction of several images. Clear improvements in image magnitude and resolution are seen when attenuation compensation is included.

Treeby, Bradley E.; Laufer, Jan G.; Zhang, Edward Z.; Norris, Francesca C.; Lythgoe, Mark F.; Beard, Paul C.; Cox, B. T.

2011-03-01

149

77 FR 42802 - Section 4(f) Policy Paper  

Federal Register 2010, 2011, 2012, 2013, 2014

...FHWA-2011-0125] Section 4(f) Policy Paper AGENCY: Federal Highway Administration...availability of the final Section 4(f) Policy Paper that will provide guidance on the procedures...copy of the final Section 4(f) Policy Paper may be viewed and copied at the...

2012-07-20

150

77 FR 321 - Section 4(f) Policy Paper  

Federal Register 2010, 2011, 2012, 2013, 2014

...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

151

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

152

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

153

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

154

Acoustic characterization of ultrasound contrast microbubbles and echogenic liposomes: Applications to imaging and drug-delivery  

NASA Astrophysics Data System (ADS)

Micron- to nanometer - sized ultrasound agents, like encapsulated microbubbles and echogenic liposomes (ELIPs), are being actively developed for possible clinical implementations in diagnostic imaging and ultrasound mediated drug/gene delivery. The primary objective of this thesis is to characterize the acoustic behavior of and the ultrasound-mediated contents release from these contrast agents for developing multi-functional ultrasound contrast agents. Subharmonic imaging using contrast microbubbles can improve image quality by providing a higher signal to noise ratio. However, the design and development of contrast microbubbles with favorable subharmonic behavior requires accurate mathematical models capable of predicting their nonlinear dynamics. To this goal, 'strain-softening' viscoelastic interfacial models of the encapsulation were developed and subsequently utilized to simulate the dynamics of encapsulated microbubbles. A hierarchical two-pronged approach of modeling --- a model is applied to one set of experimental data to obtain the model parameters (material characterization), and then the model is validated against a second independent experiment --- is demonstrated in this thesis for two lipid coated (SonazoidRTM and DefinityRTM) and a few polymer (polylactide) encapsulated microbubbles. The proposed models were successful in predicting several experimentally observed behaviors e.g., low subharmonic thresholds and "compression-only" radial oscillations. Results indicate that neglecting the polydisperse size distribution of contrast agent suspensions, a common practice in the literature, can lead to inaccurate results. In vitro experimental investigation of the dependence of subharmonic response from these microbubbles on the ambient pressure is also in conformity with the recent numerical investigations, showing both increase or decrease under appropriate excitation conditions. Experimental characterization of the ELIPs and polymersomes was performed with the goal of demonstrating their potential as ultrasound agents with simultaneous imaging and drug/gene delivery applications --- 'dual-purpose' contrast agents. Both in vitro acoustic studies and ultrasound imaging (performed in NDSU by our collaborators) showed the echogenicity of the various formulations studied. We believe that this echogenicity results from the larger diameter liposomes present in the polydisperse suspension obtained after reconstitution of the lyophilized powders. Although, ultrasound excitation (< 5 MHz) alone was incapable of causing optimal release of contents, a dual-triggering strategy (with enzymes or redox) proved successful, resulting in a total release of up to 80-90%. Considering these experimental results, it can be concluded that these novel formulations hold the potential of providing powerful treatment strategies for many diseases, including cardiovascular ones and various cancers.

Paul, Shirshendu

155

Digital image processing of sectorial oscillations for acoustically levitated drops and surface tension measurement  

NASA Astrophysics Data System (ADS)

A type of non-axisymmetric oscillations of acoustically levitated drops is excited by modulating the ultrasound field at proper frequencies. These oscillations are recorded by a high speed camera and analyzed with a digital image processing method. They are demonstrated to be the third mode sectorial oscillations, and their frequencies are found to decrease with the increase of equatorial radius of the drops, which can be described by a modified Rayleigh equation. These oscillations decay exponentially after the cessation of ultrasound field modulation. The decaying rates agree reasonably with Lamb's prediction. The rotating rate of the drops accompanying the shape oscillations is found to be less than 1.5 rounds per second. The surface tension of aqueous ethanol has been measured according to the modified Rayleigh equation. The results agree well with previous reports, which demonstrates the possible application of this kind of sectorial oscillations in noncontact measurement of liquid surface tension.

Shen, Changle; Xie, Wenjun; Wei, Bingbo

2010-12-01

156

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

157

Correlation Time of Ocean Ambient Noise Intensity in San Diego Bay and Target Recognition in Acoustic Daylight Images  

NASA Astrophysics Data System (ADS)

A method for passively detecting and imaging underwater targets using ambient noise as the sole source of illumination (named acoustic daylight) was successfully implemented in the form of the Acoustic Daylight Ocean Noise Imaging System (ADONIS). In a series of imaging experiments conducted in San Diego Bay, where the dominant source of high-frequency ambient noise is snapping shrimp, a large quantity of ambient noise intensity data was collected with the ADONIS (Epifanio, 1997). In a subset of the experimental data sets, fluctuations of time-averaged ambient noise intensity exhibited a diurnal pattern consistent with the increase in frequency of shrimp snapping near dawn and dusk. The same subset of experimental data is revisited here and the correlation time is estimated and analysed for sequences of ambient noise data several minutes in length, with the aim of detecting possible periodicities or other trends in the fluctuation of the shrimp-dominated ambient noise field. Using videos formed from sequences of acoustic daylight images along with other experimental information, candidate segments of static-configuration ADONIS raw ambient noise data were isolated. For each segment, the normalized intensity auto-correlation closely resembled the delta function, the auto-correlation of white noise. No intensity fluctuation patterns at timescales smaller than a few minutes were discernible, suggesting that the shrimp do not communicate, synchronise, or exhibit any periodicities in their snapping. Also presented here is a ADONIS-specific target recognition algorithm based on principal component analysis, along with basic experimental results using a database of acoustic daylight images.

Wadsworth, Adam J.

158

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

PubMed Central

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

159

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

160

Evolution of water-in-oil emulsion controlled by droplet-bulk ion exchange: acoustic, electroacoustic, conductivity and image analysis  

Microsoft Academic Search

Water-in-kerosene emulsion stabilized with SPAN surfactant exhibits a slow transition (on scale of hours) from an emulsion to a mini-emulsion state. We continuously monitor this transition in the relatively concentrated samples (5vol.% water), without dilution, using acoustic, electroacoustic and conductivity measurements. Continuous stirring prevents sedimentation. We confirm our measurements with microscopic image analysis and by comparing with a stable water-in-car

A. Dukhin; P. Goetz

2005-01-01

161

Evaluation of acoustic radiation force impulse imaging for the clinicopathological typing of renal fibrosis  

PubMed Central

This study aimed to explore the assessment value of virtual touch quantization (VTQ) for the clinicopathological typing of renal fibrosis. The quantitative detection of 76 patients with nephropathy was performed using acoustic radiation force impulse imaging (ARFI). The extent of the renal fibrosis in each patient was confirmed using ultrasound-guided biopsy pathology. The VTQ values were compared with the degree of renal fibrosis in order to analyze the correlation between them. Patients were divided pathologically into four groups, as follows: non-fibrosis (n=14), mild fibrosis (n=40), moderate fibrosis (n=21) and severe fibrosis (n=1). Compared with the non-fibrosis group, the VTQ values of the mild and moderate fibrosis groups were significantly increased (P<0.01); however, there was no significant difference between the VTQ values of the mild and moderate fibrosis groups (P>0.05). According to the receiver operating characteristic (ROC) curve, a VTQ value of renal parenchyma of >1.67 m/sec was determined to be an indicator of renal fibrosis, with a sensitivity of 86.3% and a specificity of 83.3%. VTQ technology may be significant in the assessment of the extent of renal fibrosis. PMID:24348796

CUI, GUANGHE; YANG, ZHI; ZHANG, WENXIAO; LI, BAOWEI; SUN, FANG; XU, CUI; WANG, KUN

2014-01-01

162

Super-resolution imaging by resonant tunneling in anisotropic acoustic metamaterials.  

PubMed

The resonant tunneling effects that could result in complete transmission of evanescent waves are examined in acoustic metamaterials of anisotropic effective mass. The tunneling conditions are first derived for the metamaterials composed of classical mass-in-mass structures. It is found that the tunneling transmission occurs when the total length of metamaterials is an integral number of half-wavelengths of the periodic Bloch wave. Due to the local resonance of building units of metamaterials, the Bloch waves are spatially modulated within the periodic structures, leading to the resonant tunneling occurring in the low-frequency region. The metamaterial slab lens with anisotropic effective mass is designed by which the physics of resonant tunneling and the features for evanescent field manipulations are examined. The designed lens interacts with evanescent waves in the way of the propagating wavenumber weakly dependent on the spatial frequency of evanescent waves. Full-wave simulations validate the imaging performance of the proposed lens with the spatial resolution beyond the diffraction limit. PMID:23039546

Liu, Aiping; Zhou, Xiaoming; Huang, Guoliang; Hu, Gengkai

2012-10-01

163

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

SciTech Connect

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 Rayleigh Bénard convection. The apparatus was validated by observing convection rolls in 5cSt polydimethylsiloxane (PDMS) polymer fluid. Our first objective, after having built the apparatus, was to use it to study the sequence of transitions from diffusive to time--dependent heat transport in liquid mercury. The aim was to provide important information on pattern formation in the largely unexplored regime of very low Prandtl number fluids. Based on the theoretical stability diagram for liquid mercury, we anticipated that straight rolls should be stable over a range of Rayleigh numbers, between 1708 and approximately 1900. Though some of our power spectral densities were suggestive of the existence of weak convection, we have been unable to unambiguously visualize stable convection rolls above the theoretical onset of convection in liquid mercury. Currently, we are seeking ways to increase the sensitivity of our apparatus, such as (i) improving the acoustic impedance matching between our materials in the ultrasound path and (ii) reducing the noise level in our acoustic images due to turbulence and cavitation in the cooling fluids circulating above and below our experimental cell. If we are able to convincingly improve the sensitivity of our apparatus, and we still do not observe stable convection rolls in liquid mercury, then it may be the case that the theoretical stability diagram requires revision. In that case, either (i) straight rolls are not stable in a large aspect ratio cell at the Prandtl numbers associated with liquid mercury, or (ii) they are stable, but not in the region of the stability diagram which has been studied by this experimenter. Our second objective was to use the apparatus to study other optically opaque fluids. To this end, we have obtained the first ultrasound images of Rayleigh-Bénard convection in a ferrofluid (EFH1). This project has provided a vehicle for the scientific training of five undergraduate research assistants during the past four years. It allowed students at Wisconsin Lutheran College, a small undergraduate liberal arts college in Milwaukee, to become directly involved in a significant scientific project from its inception through publication of scientific results. The funding of this project has also strengthened the research and teaching infrastructure at the Wisconsin Lutheran College in three major ways. The project has funded the PI and his students in the design and construction of a major piece of scientific apparatus which is capable of performing novel studies of Rayleigh-Bénard convection in opaque fluids. With the acquisition of this apparatus, we are able to embark on a broad research program to study problems in pattern formation in alloys, ferro-fluids, opaque gels, and liquid metals under thermal or magnetic stresses. This project has allowed the PI to purchase auxiliary equipment necessary for establishing a fluid dynamics research laboratory at the College. And this project has served as an impetus for the College to invest in a new machine shop in the basement of the Science Building at the College in order to support this, and other, scientific projects at the College. The PI has presented work funded by this grant at physics and engineering colloquia at a nearby university and at the keynote presentation at an undergraduate research symposium at Wisconsin Lutheran College. Also, the work was featured in local magazine and newspaper articles, and is described on the PI's research webpage. Such scientific outreach serves to advance the cause of science by making it interesting and accessible to a wider audience, and to bring attention to the wor

Kuehn, Kerry, K.

2008-10-28

164

A theoretical study of inertial cavitation from acoustic radiation force impulse imaging and implications for the mechanical index.  

PubMed

The mechanical index (MI) attempts to quantify the likelihood that exposure to diagnostic ultrasound will produce an adverse biological effect by a non-thermal mechanism. The current formulation of the MI implicitly assumes that the acoustic field is generated using the short pulse durations appropriate to B-mode imaging. However, acoustic radiation force impulse (ARFI) imaging employs high-intensity pulses up to several hundred acoustic periods long. The effect of increased pulse durations on the thresholds for inertial cavitation was studied computationally in water, urine, blood, cardiac and skeletal muscle, brain, kidney, liver and skin. The results indicate that, although the effect of pulse duration on cavitation thresholds in the three liquids can be considerable, reducing them by, for example, 6%-24% at 1 MHz, the effect on tissue is minor. More importantly, the frequency dependence of the MI appears to be unnecessarily conservative; that is, the magnitude of the exponent on frequency could be increased to 0.75. Comparison of these theoretical results with experimental measurements suggests that some tissues do not contain the pre-existing, optimally sized bubbles assumed for the MI. This means that in these tissues, the MI is not necessarily a strong predictor of the probability of an adverse biological effect. PMID:25592457

Church, Charles C; Labuda, Cecille; Nightingale, Kathryn

2015-02-01

165

The coordination chemistry and magnetism of some 3d–4f and 4f amino-polyalcohol compounds  

PubMed Central

Triethanolamine, teaH3, and diethanolamine, RdeaH2, 3d–4f and 4f compounds demonstrate an enormous variety in their structure and bonding. This review examines the synthetic strategies to these molecules and their magnetic properties, whilst trying to assess these ligands’ suitability towards new SMMs and magnetic refrigerants. PMID:25009361

Sharples, Joseph W.; Collison, David

2014-01-01

166

Quantitative non-linear ultrasonic imaging of targets with significant acoustic impedance contrast--an experimental study.  

PubMed

This study deals with the reconstruction, from ultrasonic measured data, of the sound speed profile of a penetrable two-dimensional target of arbitrary cross-section embedded in an infinite medium. Green's theorem is used to obtain a domain integral representation of the acoustical scattered field, and a discrete formulation of the inverse problem is obtained using a moment method. An iterative non-linear algorithm minimizing the discrepancy between the measured and computed scattered fields is used to reconstruct the sound speed profile in the region of interest. The minimization process is performed using a conjugated-gradient method. An experimental study with significant acoustical impedance contrast targets immersed in water was performed. Images of the sound speed profile obtained by inversion of experimental data are presented. PMID:23927099

Guillermin, Régine; Lasaygues, Philippe; Rabau, Guy; Lefebvre, Jean-Pierre

2013-08-01

167

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

168

MO Kerr study of the 4f 1 state  

NASA Astrophysics Data System (ADS)

Recent measurements of the magneto-optical Kerr effect of the cerium monochalcogenides and monopnictides have brought a deeper insight into the character of the 4f 1 state. In these materials, the 4f ? 5d transitions give rise to very sharp and larger Kerr rotation peaks. Among these, one finds the three largest ever measured Kerr rotation angles of 90°, 22.1° and 9.2° for cleaved single crystals of CeSb, CeS and CeBi, respectively. Furthermore, for the 4f 1 level, the effect of pf mixing has been found to be significant.

Pittini, R.; Schoenes, J.; Wachter, P.

1997-02-01

169

Evidence of 4f photoemission satellites in cerium compounds  

NASA Astrophysics Data System (ADS)

Experiments on CeP, CeAs, and CeBi have revealed two 4f-derived photoemission features at binding energies of 0.6 eV [FWHM (full width at half maximum)~0.7 eV] and 3.0-3.1 eV (FWHM ~ 1.0 eV) due to competing Ce 4f photoionization channels. The relative intensity of the two spectral features changes by ~ 10 from CeP to CeBi. These findings indicate strong f-p hybridization and force a reevaluation of previous 4f binding energies in Ce compounds.

Franciosi, A.; Weaver, J. H.; Mårtensson, Nils; Croft, M.

1981-09-01

170

4f electron delocalization and volume collapse in praseodymium metal  

SciTech Connect

We study the pressure evolution of the 4f electrons in elemental praseodymium metal compressed through several crystallographic phases, including the large volume-collapse transition at 20 GPa. Using resonant x-ray emission, we directly and quantitatively measure the development of multiple electronic configurations with differing 4f occupation numbers, the key quantum observable related to the delocalization of the strongly correlated 4f electrons. These results provide a high-fidelity test of prior predictions by dynamical mean-field theory, and support the hypothesis of a strong connection between electronic and structural degrees of freedom at the volume-collapse transition.

Bradley, Joseph A.; Moore, Kevin T.; Lipp, Magnus J.; Mattern, Brian A.; Pacold, Joseph I.; Seidler, Gerald T.; Chow, Paul; Rod, Eric; Xiao, Yuming; Evans, William J. (UWASH); (LLNL); (CIW)

2012-04-17

171

Comparative study of acoustic radiation force impulse imaging with real-time elastography in differential diagnosis of thyroid nodules.  

PubMed

The aims of this study were to evaluate whether acoustic radiation force impulse (ARFI) imaging of the thyroid gland and thyroid nodules yields reliable results and to compare the values of ARFI imaging with those of real-time elastography (RTE) in the differential diagnosis of thyroid nodules. RTE and ARFI were performed in 30 patients with 58 thyroid nodules. The results were compared with pathologic findings. Receiver operating characteristic curves were drawn to evaluate the diagnostic results. The area under the curve for RTE (0.78) was smaller than that for ARFI (0.94) (p < 0.01). ARFI imaging of thyroid tissue yields more reliable results than RTE. PMID:24120414

Zhan, Jia; Diao, Xue-Hong; Chai, Qi-Liang; Chen, Yue

2013-12-01

172

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

NASA Astrophysics Data System (ADS)

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.

2005-05-01

173

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

E-print Network

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

Zhang, Junshan

174

23 CFR 774.3 - Section 4(f) approvals.  

Code of Federal Regulations, 2010 CFR

...AND ENVIRONMENT PARKS, RECREATION AREAS, WILDLIFE AND WATERFOWL REFUGES, AND HISTORIC SITES (SECTION 4(F)) § 774...Involvement With Public Parks, Recreation Lands, Wildlife and Waterfowl Refuges, and Historic Sites; (3) Final Nationwide...

2010-04-01

175

23 CFR 774.3 - Section 4(f) approvals.  

Code of Federal Regulations, 2014 CFR

...AND ENVIRONMENT PARKS, RECREATION AREAS, WILDLIFE AND WATERFOWL REFUGES, AND HISTORIC SITES (SECTION 4(f)) § 774...Involvement With Public Parks, Recreation Lands, Wildlife and Waterfowl Refuges, and Historic Sites; (3) Final Nationwide...

2014-04-01

176

23 CFR 774.3 - Section 4(f) approvals.  

Code of Federal Regulations, 2011 CFR

...AND ENVIRONMENT PARKS, RECREATION AREAS, WILDLIFE AND WATERFOWL REFUGES, AND HISTORIC SITES (SECTION 4(F)) § 774...Involvement With Public Parks, Recreation Lands, Wildlife and Waterfowl Refuges, and Historic Sites; (3) Final Nationwide...

2011-04-01

177

23 CFR 774.3 - Section 4(f) approvals.  

Code of Federal Regulations, 2012 CFR

...AND ENVIRONMENT PARKS, RECREATION AREAS, WILDLIFE AND WATERFOWL REFUGES, AND HISTORIC SITES (SECTION 4(F)) § 774...Involvement With Public Parks, Recreation Lands, Wildlife and Waterfowl Refuges, and Historic Sites; (3) Final Nationwide...

2012-04-01

178

23 CFR 774.3 - Section 4(f) approvals.  

Code of Federal Regulations, 2013 CFR

...AND ENVIRONMENT PARKS, RECREATION AREAS, WILDLIFE AND WATERFOWL REFUGES, AND HISTORIC SITES (SECTION 4(F)) § 774...Involvement With Public Parks, Recreation Lands, Wildlife and Waterfowl Refuges, and Historic Sites; (3) Final Nationwide...

2013-04-01

179

ACOUSTICAL IMAGING AND MECHANICAL PROPERTIES OF SOFT ROCK AND MARINE SEDIMENTS  

SciTech Connect

Mechanically weak formations, such as chalks, high porosity sandstones, and marine sediments, pose significant problems for oil and gas operators. Problems such as compaction, subsidence, and loss of permeability can affect reservoir production operations. For example, the unexpected subsidence of the Ekofisk chalk in the North Sea required over one billion dollars to re-engineer production facilities to account for losses created during that compaction (Sulak 1991). Another problem in weak formations is that of shallow water flows (SWF). Deep water drilling operations sometimes encounter cases where the marine sediments, at shallow depths just below the seafloor, begin to uncontrollably flow up and around the drill pipe. SWF problems created a loss of $150 million for the Ursa development project in the U.S. Gulf Coast SWF (Furlow 1998a,b; 1999a,b). The goal of this project is to provide a database on both the rock mechanical properties and the geophysical properties of weak rocks and sediments. These could be used by oil and gas companies to detect, evaluate, and alleviate potential production and drilling problems. The results will be useful in, for example, pre-drill detection of events such as SWF's by allowing a correlation of seismic data (such as hazard surveys) to rock mechanical properties. The data sets could also be useful for 4-D monitoring of the compaction and subsidence of an existing reservoir and imaging the zones of damage. During the second quarter of the project the research team has: (1) completed acoustic sensor construction, (2) conducted reconnaissance tests to map the deformational behaviors of the various rocks, (3) developed a sample assembly for the measurement of dynamic elastic and poroelastic parameters during triaxial testing, and (4) conducted a detailed review of the scientific literature and compiled a bibliography of that review. During the first quarter of the project the research team acquired several rock types for testing including: (a) Danian chalk, (b) Cordoba Cream limestone, (c) Indiana limestone, (d) Ekofisk chalk, (e) Oil Creek sandstone, (f) unconsolidated Oil Creek sand, and (g) unconsolidated Brazos river sand. During the second quarter experiments were begun on these rock types. A series of reconnaissance experiments have been carried out on all but the Ekofisk (for which there is a preliminary data set already inhouse). A series of triaxial tests have been conducted on the Danian chalk, the Cordoba Cream limestone, the Indiana limestone, and sand samples to make a preliminary determination of the deformational mechanisms present in these samples.

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

2001-07-01

180

Direct imaging of the acoustic waves generated by femtosecond filaments in air.  

PubMed

We present time-resolved measurements of the gas acoustic dynamics following interaction of spatial single- and higher-mode 50 fs, 800 nm pulses in air at 10 Hz and 1 kHz repetition rates. Results are in excellent agreement with hydrodynamic simulations. Under no conditions for single filaments do we find on-axis enhancement of gas density; this occurs only with multifilaments. We also investigate the propagation of probe beams in the gas density profile induced by a single extended filament. We find that light trapping in the expanding annular acoustic wave can create the impression of on-axis guiding in a limited temporal window. PMID:24690729

Wahlstrand, J K; Jhajj, N; Rosenthal, E W; Zahedpour, S; Milchberg, H M

2014-03-01

181

Direct imaging of the acoustic waves generated by femtosecond filaments in air  

NASA Astrophysics Data System (ADS)

We present direct measurements of the gas acoustic dynamics following interaction of spatial single- and multi-mode 50 fs, 800 nm pulses in air at 10 Hz and 1 kHz repetition rates. Results are in excellent agreement with hydrodynamic simulations. Under no conditions for single filaments do we find on-axis enhancement of gas density; this occurs only with multi-filaments. We also investigate the propagation of probe beams in the gas density profile induced by a single extended filament. We find that light trapping in the expanding annular acoustic wave can create the impression of on-axis guiding in a limited temporal window.

Wahlstrand, J. K.; Jhajj, N.; Rosenthal, E. W.; Zahedpour, S.; Milchberg, H. M.

2014-03-01

182

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

183

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

SciTech Connect

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 km{sup 2}, which encompasses a volume of about 3.2 million m{sup 3}. 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 30 m 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.

Hampton, M A. (U. S. Geological Survey); Karl, H (.); Murray, Christopher J. (BATTELLE (PACIFIC NW LAB))

2001-12-01

184

Comparison of temporal and spectral scattering methods using acoustically large breast models derived from magnetic resonance images.  

PubMed

Accurate and efficient modeling of ultrasound propagation through realistic tissue models is important to many aspects of clinical ultrasound imaging. Simplified problems with known solutions are often used to study and validate numerical methods. Greater confidence in a time-domain k-space method and a frequency-domain fast multipole method is established in this paper by analyzing results for realistic models of the human breast. Models of breast tissue were produced by segmenting magnetic resonance images of ex vivo specimens into seven distinct tissue types. After confirming with histologic analysis by pathologists that the model structures mimicked in vivo breast, the tissue types were mapped to variations in sound speed and acoustic absorption. Calculations of acoustic scattering by the resulting model were performed on massively parallel supercomputer clusters using parallel implementations of the k-space method and the fast multipole method. The efficient use of these resources was confirmed by parallel efficiency and scalability studies using large-scale, realistic tissue models. Comparisons between the temporal and spectral results were performed in representative planes by Fourier transforming the temporal results. An RMS field error less than 3% throughout the model volume confirms the accuracy of the methods for modeling ultrasound propagation through human breast. PMID:25096103

Hesford, Andrew J; Tillett, Jason C; Astheimer, Jeffrey P; Waag, Robert C

2014-08-01

185

Comparative evaluation of ultrasonic lenses and electric point contacts for acoustic flux imaging in piezoelectric single crystals  

NASA Astrophysics Data System (ADS)

Conducting micro-spheres approximating point probes have been employed to piezoelectrically excite and detect ultrasonic wave packages in anisotropic single crystals. Imaging based on the detection of magnitude and phase is performed in transmission. The experimental data can be used for the determination of the elastic constants of the material. Here we compare this approach with imaging using conventional ultrasonic lenses and water as a coupling fluid. The large bandwidth and the absence of internal lens echoes in the Coulomb excitation and detection scheme permit unperturbed monitoring of multiple echoes in plane-parallel samples and the detailed investigation of mode conversion processes of longitudinal and transverse waves at the surfaces of the crystal. Due to differences in the coupling between the probes and the ultrasound in the sample, excitation of ultrasound by an acoustic lens or an electrical point contact, respectively, result in noticeably different phonon focusing patterns. This is illustrated for lithium niobate single crystals.

Twerdowski, E.; Pluta, M.; Wannemacher, R.; Grill, W.

2008-03-01

186

Experimental Study of High-Range-Resolution Medical Acoustic Imaging for Multiple Target Detection by Frequency Domain Interferometry  

NASA Astrophysics Data System (ADS)

We employed frequency domain interferometry (FDI) for use as a medical acoustic imager to detect multiple targets with high range resolution. The phase of each frequency component of an echo varies with the frequency, and target intervals can be estimated from the phase variance. This processing technique is generally used in radar imaging. When the interference within a range gate is coherent, the cross correlation between the desired signal and the coherent interference signal is nonzero. The Capon method works under the guiding principle that output power minimization cancels the desired signal with a coherent interference signal. Therefore, we utilize frequency averaging to suppress the correlation of the coherent interference. The results of computational simulations using a pseudoecho signal show that the Capon method with adaptive frequency averaging (AFA) provides a higher range resolution than a conventional method. These techniques were experimentally investigated and we confirmed the effectiveness of the proposed method of processing by FDI.

Kimura, Tomoki; Taki, Hirofumi; Sakamoto, Takuya; Sato, Toru

2009-07-01

187

Noninvasive Ultrasound Imaging for Bone Quality Assessment Using Scanning Confocal Acoustic Diagnosis, ?CT, DXA Measurements, and Mechanical Testing  

NASA Astrophysics Data System (ADS)

Osteoporosis is a disease characterized by decreased bone mass and progressive deterioration of the microstructure, affecting both mineral density and bone's fragility. Current diagnoses are only measuring apparent bone mineral density (AppBMD). Using our newly developed scanning confocal acoustic diagnostic (SCAD) system, we evaluated the ability of quantitative ultrasound in noninvasively predicting bone's quantity and quality on 19 human cadaver calcanei. Results show that ultrasound attenuation image on intact calcaneus represents bone mass distribution. High correlation (R=0.82) exists between SCAD determined broadband ultrasound attenuation (BUA) and DXA determined AppBMD at the calcaneus, as well as in the AppBMD result at femoral neck (R=0.81). SCAD determined BUA and ultrasound velocity (UV) are highly correlated with the micro-CT and mechanical testing determined bone quantity and quality parameters. These results suggest that image-based quantitative ultrasound is able to identify ROI and predict both bone mass and strength.

Qin, Yi-Xian; Xia, Yi; Lin, Wei; Mittra, Erik; Rubin, Clint; Gruber, Barry

188

Acoustic nonlinear amplitude versus angle inversion and data-driven depth imaging in stratified media derived from inverse scattering approximations  

NASA Astrophysics Data System (ADS)

This paper presents a new theory for nonlinear direct amplitude versus angle (AVA) inversion and data-driven depth imaging for a depth-variable acoustic medium. The method which is derived by direct inversion of the forward model of acoustic single scattering requires no information of the velocity and density potentials (subsurface properties), except for the velocity and density of the uppermost layer which is the reference medium where the source and receiver are situated at a finite distance above the scattering medium. The vertically varying velocity and density of the scattering medium are estimated in a data-driven manner solely from the angle- and depth-dependent Born potential profile. The inversion method is obtained in three main steps. In step one, the Born potential profile is computed by constant-velocity imaging (migration) of the single scattering data in the time intercept-slowness domain. Generally, interfaces in the Born potential are severely mislocated in depth compared to the true potential. In step two, 'squeezed' depth-dependent velocity and density potentials are estimated by nonlinear direct AVA inversion of the Born potential after residual-moveout correction. Step three estimates the actual depth-dependent velocity and density potentials by stretching the squeezed potentials so that their interfaces are moved towards the correct depth. In the nomenclature of seismic processing, the three steps can be described by the sequence constant-velocity (partial) migration-inversion-residual migration. In contrast to conventional, velocity-dependent depth migration, which requires an accurate estimate of the velocities of the actual medium to obtain the proper image, the depth imaging in step three requires the squeezed actual velocity potential with interfaces matching those of the zero-angle Born potential depth profile. This is exactly the velocity potential that is found in step two.

Amundsen, Lasse; Reitan, Arne; Arntsen, Børge; Ursin, Bjørn

2006-12-01

189

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.

190

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

191

B-mode and acoustic radiation force impulse (ARFI) imaging of prostate zonal anatomy: comparison with 3T T2-weighted MR imaging.  

PubMed

Prostate cancer (PCa) is the most common non-cutaneous malignancy among men in the United States and the second leading cause of cancer-related death. Multi-parametric magnetic resonance imaging (mpMRI) has gained recent popularity to characterize PCa. Acoustic Radiation Force Impulse (ARFI) imaging has the potential to aid PCa diagnosis and management by using tissue stiffness to evaluate prostate zonal anatomy and lesions. MR and B-mode/ARFI in vivo imaging datasets were compared with one another and with gross pathology measurements made immediately after radical prostatectomy. Images were manually segmented in 3D Slicer to delineate the central gland (CG) and prostate capsule, and 3D models were rendered to evaluate zonal anatomy dimensions and volumes. Both imaging modalities showed good correlation between estimated organ volume and gross pathologic weights. Ultrasound and MR total prostate volumes were well correlated (R(2) = 0.77), but B-mode images yielded prostate volumes that were larger (16.82% ± 22.45%) than MR images, due to overestimation of the lateral dimension (18.4% ± 13.9%), with less significant differences in the other dimensions (7.4% ± 17.6%, anterior-to-posterior, and -10.8% ± 13.9%, apex-to-base). ARFI and MR CG volumes were also well correlated (R(2) = 0.85). CG volume differences were attributed to ARFI underestimation of the apex-to-base axis (-28.8% ± 9.4%) and ARFI overestimation of the lateral dimension (21.5% ± 14.3%). B-mode/ARFI imaging yielded prostate volumes and dimensions that were well correlated with MR T2-weighted image (T2WI) estimates, with biases in the lateral dimension due to poor contrast caused by extraprostatic fat. B-mode combined with ARFI imaging is a promising low-cost, portable, real-time modality that can complement mpMRI for PCa diagnosis, treatment planning, and management. PMID:25060914

Palmeri, Mark L; Miller, Zachary A; Glass, Tyler J; Garcia-Reyes, Kirema; Gupta, Rajan T; Rosenzweig, Stephen J; Kauffman, Christopher; Polascik, Thomas J; Buck, Andrew; Kulbacki, Evan; Madden, John; Lipman, Samantha L; Rouze, Ned C; Nightingale, Kathryn R

2015-01-01

192

Evidence from acoustic imaging for submarine volcanic activity in 2012 off the west coast of El Hierro (Canary Islands, Spain)  

NASA Astrophysics Data System (ADS)

We report precursory geophysical, geodetic, and geochemical signatures of a new submarine volcanic activity observed off the western coast of El Hierro, Canary Islands. Submarine manifestation of this activity has been revealed through acoustic imaging of submarine plumes detected on the 20-kHz chirp parasound subbottom profiler (TOPAS PS18) mounted aboard the Spanish RV Hespérides on June 28, 2012. Five distinct "filament-shaped" acoustic plumes emanating from the flanks of mounds have been recognized at water depth between 64 and 88 m on a submarine platform located NW El Hierro. These plumes were well imaged on TOPAS profiles as "flares" of high acoustic contrast of impedance within the water column. Moreover, visible plumes composed of white rafts floating on the sea surface and sourcing from the location of the submarine plumes were reported by aerial photographs on July 3, 2012, 5 days after acoustic plumes were recorded. In addition, several geophysical and geochemical data support the fact that these submarine vents were preceded by several precursory signatures: (i) a sharp increase of the seismic energy release and the number of daily earthquakes of magnitude ?2.5 on June 25, 2012, (ii) significant vertical and horizontal displacements observed at the Canary Islands GPS network (Nagoya University-ITER-GRAFCAN) with uplifts up to 3 cm from June 25 to 26, 2012, (iii) an anomalous increase of the soil gas radon activity, from the end of April until the beginning of June reaching peak values of 2.7 kBq/m3 on June 3, 2012, and (iv) observed positive peak in the air-corrected value of 3He/4He ratio monitored in ground waters (8.5 atmospheric 3He/4He ratio ( R A)) at the northwestern El Hierro on June 16, 2012. Combining these submarine and subaerial information, we suggest these plumes are the consequence of submarine vents exhaling volcanic gas mixed with fine ash as consequence of an event of rapid rise of volatile-rich magma beneath the NW submarine ridge of El Hierro. These precursory signals have revealed important to improve and optimize the detection of early warning signals of volcanic unrest episodes at El Hierro.

Pérez, Nemesio M.; Somoza, Luis; Hernández, Pedro A.; de Vallejo, Luis González; León, Ricardo; Sagiya, Takeshi; Biain, Ander; González, Francisco J.; Medialdea, Teresa; Barrancos, José; Ibáñez, Jesús; Sumino, Hirochika; Nogami, Kenji; Romero, Carmen

2014-12-01

193

Redetermination of durangite, NaAl(AsO4)F  

PubMed Central

The crystal structure of durangite, ideally NaAl(AsO4)F (chemical name sodium aluminium arsenate fluoride), has been determined previously [Kokkoros (1938). Z. Kristallogr. 99, 38–49] using Weissenberg film data without reporting displacement parameters of atoms or a reliability factor. This study reports the redetermination of the structure of durangite using single-crystal X-ray diffraction data from a natural sample with composition (Na0.95Li0.05)(Al0.91Fe3+ 0.07Mn3+ 0.02)(AsO4)(F0.73(OH)0.27) from the type locality, the Barranca mine, Coneto de Comonfort, Durango, Mexico. Durangite is isostructural with minerals of the titanite group in the space group C2/c. Its structure is characterized by kinked chains of corner-sharing AlO4F2 octa­hedra parallel to the c axis. These chains are cross-linked by isolated AsO4 tetra­hedra, forming a three-dimensional framework. The Na+ cation (site symmetry 2) occupies the inter­stitial sites and is coordinated by one F? and six O2? anions. The AlO4F2 octa­hedron has symmetry -1; it is flattened, with the Al—F bond length [1.8457?(4)?Å] shorter than the Al—O bond lengths [1.8913?(8) and 1.9002?(9)?Å]. Examination of the Raman spectra for arsenate minerals in the titanite group reveals that the position of the band originating from the As—O symmetric stretching vibrations shifts to lower wavenumbers from durangite, maxwellite [ideally NaFe(AsO4)F], to tilasite [CaMg(AsO4)F]. PMID:23284315

Downs, Gordon W.; Yang, Betty N.; Thompson, Richard M.; Wenz, Michelle D.; Andrade, Marcelo B.

2012-01-01

194

Density Functional Study of Structures and Electron Affinities of BrO4F/BrO4F?  

PubMed Central

The structures, electron affinities and bond dissociation energies of BrO4F/BrO4F? species have been investigated with five density functional theory (DFT) methods with DZP++ basis sets. The planar F-Br…O2…O2 complexes possess 3A? electronic state for neutral molecule and 4A? state for the corresponding anion. Three types of the neutral-anion energy separations are the adiabatic electron affinity (EAad), the vertical electron affinity (EAvert), and the vertical detachment energy (VDE). The EAad value predicted by B3LYP method is 4.52 eV. The bond dissociation energies De (BrO4F ? BrO4-mF + Om) (m = 1–4) and De? (BrO4F? ? BrO4-mF? + Om and BrO4F? ? BrO4-mF + Om?) are predicted. The adiabatic electron affinities (EAad) were predicted to be 4.52 eV for F-Br…O2…O2 (3A??4A?) (B3LYP method). PMID:19742128

Gong, Liangfa; Xiong, Jieming; Wu, Xinmin; Qi, Chuansong; Li, Wei; Guo, Wenli

2009-01-01

195

Acoustic characterization and contrast imaging of microbubbles encapsulated by polymeric shells coated or filled with magnetic nanoparticles.  

PubMed

The combination of superparamagnetic iron oxide nanoparticles with polymeric air-filled microbubbles is used to produce two types of multimodal contrast agents to enhance medical ultrasound and magnetic resonance imaging. The nanoparticles are either covalently linked to the shell or physically entrapped into the shell. In this paper, the characterization of the acoustic properties (backscattered power, fracturing pressure, attenuation and dispersion of the ultrasonic wave) and ultrasound imaging of the two types of magnetic microbubbles are presented. In vitro B-mode images are generated using a medical ultrasound scanner by applying a nonconventional signal processing technique that is suitable to detect polymeric bubbles and based on the combination of multipulse excitation and chirp coding. Even if both types of microbubbles can be considered to be effective ultrasound contrast agents, the different structure of the shell loaded with nanoparticles has a pronounced effect on the echogenicity and the detection sensitivity of the imaging technique. The best results are obtained using microbubbles that are externally coated with nanoparticles. A backscattered power of 20?dB was achieved at lower concentration, and an increment of 8?dB in the contrast-to-tissue ratio was observed with respect to the more rigid microbubbles with particles entrapped into the shell. PMID:24180801

Sciallero, Claudia; Grishenkov, Dmitry; Kothapalli, Satya V V N; Oddo, Letizia; Trucco, Andrea

2013-11-01

196

Acoustics and Vibration Animations  

NSDL National Science Digital Library

Dan Russell, a professor of Applied Physics at Ketting University, created this site to provide students animated images of sounds and vibrations produced by instruments such as loudspeakers and guitars. The site is divided into three sections, which include: "Acoustics I: Sounds and Sources," "Acoustics II: Sound and Vibration," and "Other Wave Phenomena (not acoustics, but still waves)." This site will surely be of assistance to those struggling with the intangible realities of wave phenomena.

Russell, Daniel A.

197

Detecting the activation of a self-healing mechanism in concrete by acoustic emission and digital image correlation.  

PubMed

Autonomous crack healing in concrete is obtained when encapsulated healing agent is embedded into the material. Cracking damage in concrete elements ruptures the capsules and activates the healing process by healing agent release. Previously, the strength and stiffness recovery as well as the sealing efficiency after autonomous crack repair was well established. However, the mechanisms that trigger capsule breakage remain unknown. In parallel, the conditions under which the crack interacts with embedded capsules stay black-box. In this research, an experimental approach implementing an advanced optical and acoustic method sets up scopes to monitor and justify the crack formation and capsule breakage of concrete samples tested under three-point bending. Digital Image Correlation was used to visualize the crack opening. The optical information was the basis for an extensive and analytical study of the damage by Acoustic Emission analysis. The influence of embedding capsules on the concrete fracture process, the location of capsule damage, and the differentiation between emissions due to capsule rupture and crack formation are presented in this research. A profound observation of the capsules performance provides a clear view of the healing activation process. PMID:24381518

Tsangouri, E; Aggelis, D G; Van Tittelboom, K; De Belie, N; Van Hemelrijck, D

2013-01-01

198

Technical Report SEC 17a-4(f) Compliance Assessment  

E-print Network

Technical Report SEC 17a-4(f) Compliance Assessment Prepared by Cohasset Associates, Inc. July 2010 Abstract This technical report is a compliance assessment of the storage capabilities of the IBM. | Guiding the Way to Successful Records & Information Management #12;Table of Contents 2 Technical Report

199

Section 4(f) Updates 2009 Mn/DOT Environmental  

E-print Network

Equity Act ­ Legacy for Users #12;23 CFR 774 March 12, 2008 · Additionally, 23 CFR 774 ... ­ Least harm planning to minimize harm to the ... Section 4(f) resource. #12;· Early application heavily influenced · Includes de minimis impacts · Preamble stresses importance of preservation purpose of law ­ least harm

Minnesota, University of

200

Section 4(f) Updates 2007 Mn/DOT Environmental  

E-print Network

, Aquariums & Zoos § Tribal Lands & Indian Reservations § Tiered NEPA Documents http and Determination for Federal-Aid Transportation Projects That Have a Net Benefit to a Section 4(f) Property jurisdiction will result in a net benefit to the property http://environment.fhwa.dot.gov/projdev/4fnetbenefits

Minnesota, University of

201

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

202

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

203

Wavefront modulation and subwavelength diffractive acoustics with an acoustic metasurface  

NASA Astrophysics Data System (ADS)

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.

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

2014-11-01

204

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

205

Calibration of an Optical-Acoustic Sensor  

Microsoft Academic Search

In this paper an application is described, where image registration to a model is used in conjunction with registration of acoustic (3-D) data to the same model to perform calibration of an optical\\/acoustic rig. This allows to register the video image with the depth map acquired by the acoustic device, thereby obtaining a single multisensorial image. Experimental results on both

Andrea Fusiello; Vittorio Murino

2000-01-01

206

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

207

Ultrasonic imaging of an object at the presence of Fourier and non-Fourier transformation in the transmitted through the object acoustic field.  

PubMed

A metal object is computer visualized by registration of the amplitudes of the transmitted through the object short acoustic pulses. The pulses are separated by time, because of the presence of holes and internal compact components in the longitudinal section (structure along the propagation direction of acoustic wave). The acoustic field transmitted through the object is composited from a field presenting Fourier transformation of the hole shape and field, transmitted through the metal components in the longitudinal section of the object. A computer Fourier transformation of the digital data of the amplitude fields transmitted through the object components is performed instead of converging lens. The Fourier series of the object obtained as digital data after the transformation is multiplied with a term, describing the angle distribution of the field on spatial frequencies. The reconstruction of the image of the metal components is performed by reverse transformation, i.e. summing up in all spatial frequencies. 3D visualization of the transmitted through the hole acoustic field determines the hole geometry (circular, square, rectangular). It is shown that at the transmission of a short acoustic pulse through the components with different thicknesses and holes, presenting Fourier and non-Fourier transformation can be registered separately in contrast to the optics. PMID:17395232

Andreeva, A; Burova, M; Burov, J

2007-06-01

208

Ion effects on CF2 surface interactions during C3F8 and C4F8 plasma processing of Si  

Microsoft Academic Search

Surface interactions of difluorocarbene (CF2) molecules were investigated using our LIF based imaging of radicals interacting with surfaces (IRIS) apparatus. LIF data of CF2 in C3F8 and C4F8 plasma molecular beams reveal that the relative densities of CF2 increase with increasing rf power and source pressure in both plasma systems. The surface reactivity of CF2 molecules during C3F8 and C4F8

Ina T. Martin; Ellen R. Fisher

2004-01-01

209

Active and passive acoustic imaging inside a large-scale polyaxial hydraulic fracture test  

SciTech Connect

An automated laboratory hydraulic fracture experiment has been assembled to determine what rock and treatment parameters are crucial to improving the efficiency and effectiveness of field hydraulic fractures. To this end a large (460 mm cubic sample) polyaxial cell, with servo-controlled X,Y,Z, pore pressure, crack-mouth-opening-displacement, and bottom hole pressure, was built. Active imaging with embedded seismic diffraction arrays images the geometry of the fracture. Preliminary tests indicate fracture extent can be imaged to within 5%. Unique embeddible high-fidelity particle velocity AE sensors were designed and calibrated to allow determination of fracture source kinematics.

Glaser, S.D.; Dudley, J.W. II; Shlyapobersky, J.

1999-07-01

210

4f6?4f55d1 absorption spectrum analysis of Sm2+:SrCl2  

NASA Astrophysics Data System (ADS)

The 4f6?4f55d1 absorption spectrum of the Sm2+ ions incorporated in a SrCl2 single crystal was recorded at 4.2K in the 15000-45000cm-1 spectral range. The overall spectrum is very satisfactorily simulated by theoretical calculations performed in the frame of the semi-empirical Hamiltonian model. The calculations enabled the assignment of all bands observed in the spectrum as well as a prediction of some experimentally unobserved transitions in the 45000-55000cm-1 region. The rich vibronic structure observed for absorption bands in the 15000-25000cm-1 spectral region is dominated by the vibronic progressions in the totally symmetric Sr-Cl stretching mode of ˜213cm-1 upon the thirteen zero phonon lines and local vibration modes at ˜81cm-1 and ˜116cm-1 . This multiphonon vibronic spectrum is very well reproduced by the model calculation.

Karbowiak, Miros?aw; Urbanowicz, Agnieszka; Reid, Michael F.

2007-09-01

211

Classroom Acoustics  

MedlinePLUS

Classroom Acoustics A student's ability to hear and understand what is being said in the classroom is vital for ... reverberation time. Who is affected by poor classroom acoustics? All children are affected by poor classroom acoustics, ...

212

Near-infrared absorbing polymer nano-particle as a sensitive contrast agent for photo-acoustic imaging  

NASA Astrophysics Data System (ADS)

Polymer nano-particles (PNPs) with a near-infrared (NIR) light absorption were prepared by the nano-emulsion method to develop contrast agents for photo-acoustic (PA) imaging. The PNP containing silicon naphthalocyanine showed a high absorption coefficient up to 1010 M-1 cm-1. This is comparable to plasmonic gold nano-particles, which have been studied as PA contrast agents. For the PNP larger than 100 nm, the enhancement of the PA signal was observed compared to the gold nano-particle with a similar absorption coefficient and size. In the case of the PNP, the heat by the light absorption is confined in the particle due to the low thermal diffusivity of polymer materials. We showed that the strong thermal confinement effect of PNP results in the enhancement of the efficiency of the PA signal generation and that the PA intensity can be enhanced by the increase of the Grüneisen parameter of the matrix polymer of PNP. The PA signal from the PNP of poly(methyl methacrylate) was 9-fold larger than that of gold nano-particles with the same absorption coefficient. We demonstrated that in the in vivo PA imaging the detection limit of PNP was of the order of 10-13 M. The NIR absorbing PNP will be a promising candidate of a sensitive contrast agent for PA imaging.Polymer nano-particles (PNPs) with a near-infrared (NIR) light absorption were prepared by the nano-emulsion method to develop contrast agents for photo-acoustic (PA) imaging. The PNP containing silicon naphthalocyanine showed a high absorption coefficient up to 1010 M-1 cm-1. This is comparable to plasmonic gold nano-particles, which have been studied as PA contrast agents. For the PNP larger than 100 nm, the enhancement of the PA signal was observed compared to the gold nano-particle with a similar absorption coefficient and size. In the case of the PNP, the heat by the light absorption is confined in the particle due to the low thermal diffusivity of polymer materials. We showed that the strong thermal confinement effect of PNP results in the enhancement of the efficiency of the PA signal generation and that the PA intensity can be enhanced by the increase of the Grüneisen parameter of the matrix polymer of PNP. The PA signal from the PNP of poly(methyl methacrylate) was 9-fold larger than that of gold nano-particles with the same absorption coefficient. We demonstrated that in the in vivo PA imaging the detection limit of PNP was of the order of 10-13 M. The NIR absorbing PNP will be a promising candidate of a sensitive contrast agent for PA imaging. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr04724a

Aoki, Hiroyuki; Nojiri, Mayumi; Mukai, Rieko; Ito, Shinzaburo

2014-11-01

213

Error Analysis and the Computation of Turbulent Fluctuations for 3D Volume Reconstructions of Acoustic Images of Black Smoker Plumes  

NASA Astrophysics Data System (ADS)

We present an error analysis and statistical description of 3D volume reconstructions and measurements based on our acoustic images of a high-temperature black smoker-type plume. Sources of error include (1) the intrinsic variance due to particle motion in the plume since the acoustic images are based on backscatter from small (5-100 ?m) particles, (2) noise produced by the ROV Jason system on which the sonar was mounted, and (3) unwanted echos from the surrounding seafloor returning through the sonar sidelobes. Additional fluctuations in the particle concentration due to plume turbulence lead to time variations in the measured backscatter. The data were collected in July 2000 by a SM2000 (330 MHz) sonar mounted on the ROV Jason. The sonar system was calibrated to record absolute backscatter pressure. The squared magnitude of backscattered pressure is converted to differential backscatter cross-section per unit volume (units 1/m), which is proportional to particulate concentration. Three-dimensional imaging data were obtained by a combination of time gating, digital beamforming, and mechanical scanning for resolution in range, azimuth, and elevation, respectively. Several different processing steps were applied to the data to reduce the error: (a) averaging along the pings with a range window of 1 m reduced the standard error in a single ping due to intrinsic variance from 1 to 0.44, (b) narrow-band notch filtering reduced the effects of tonal noise, (c) bursts effected by occasional impulsive noise events were simply eliminated from further processing, (d) successive pings were subtracted in an effort to cancel out the effects of unwanted sidelobe returns. The resulting data were interpolated onto a uniform 3D grid with 0.5 m spacing. The statistics of six successive 3D volumes were computed. Averaging the six volumes further reduced the standard error to 0.18. The total rms error, computed as the sample standard deviation divided by the square root of 6 (the number of volumes averaged into the mean), includes all sources of random error and falls in the range 0.1-0.4x10-4 1/m. Intrinsic error (18% of mean) and rms error are both low compared to mean backscattering cross-section (core maximum is 1.1x10-4 1/m) and similar to minimum values (core minimum is 0.3x10-4 1/m). Total fluctuation in the plume structure during 20 minutes of recording (all volumes) falls in the range 0.1-3.0x10-4 1/m, with the largest values in the plume core reflecting the high variability expected in a plume core. The rms fluctuations decay upwards along the plume axis at a similar rate as the mean backscattering cross-section, indicating that the dilution process is self-similar, as in buoyant plume models, even though particles are not true passive tracers. The effective plume width increases at the predicted rate of 0.1 m/m for a fully developed plume. Despite significant error levels, the turbulence structure of the plume is observed in the acoustic data and provides some constraints on the entrainment and dilution mechanisms.

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

2002-12-01

214

Imaging and Inversion with Acoustic and Elastic Waves 1 Chapter 1.8.1  

E-print Network

. In addition, it will also be seen that the clas- sical imaging methods of seismology and ultrasonics (such that make use of array-based waveform mea- surements, such as ultrasonics, nondestructive test- ing, global, synthetic aperture focussing, and diffraction tomography; we will see shortly that these methods are special

Scales, John

215

Combined acoustic-photoacoustic and fluorescence imaging catheter for the detection of the atherosclerotic plaque  

NASA Astrophysics Data System (ADS)

In industrialized countries, cardiovascular diseases remain the main cause of mortality. The detection of atherosclerosis and its associated plaque using imaging techniques allows studying the efficacy of new drugs in vivo. Intravascular ultrasound (IVUS) imaging has been demonstrated to be a powerful tool to uncover structural information of atherosclerotic plaques. Recently, intravascular photoacoustic (IVPA) has been combined with IVUS imaging to add functional and/or molecular information. The IVPA/IVUS combination has been demonstrated in phantoms and ex vivo tissues to provide relevant information about the composition of the plaque, as well as its vulnerability. In this work, we extend previous work by developing a combined IVPA/IVUS system using a rotating ultrasound transducer in a catheter to which an optical fiber is attached. In addition, a third modality was included through fluorescence detection in the same fiber at a distinct wavelength from PA, opening the door to complementary information using fluorescence activatable probes. Cylindrical silicon phantoms with inclusions containing fluorophores or ink were used to validate the system. Bleaching of the fluorophore by the pulsed laser used for photoacoustic was quantified. IVUS images were obtained continuously and used to co-register photoacoustic and fluorescence signals.

Abran, Maxime; Matteau-Pelletier, Carl; Zerouali-Boukhal, Karim; Tardif, Jean-Claude; Lesage, Frédéric

2011-03-01

216

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

217

Towards an acoustic model-based poroelastic imaging method: II. experimental investigation.  

PubMed

Soft biological tissue contains mobile fluid. The volume fraction of this fluid and the ease with which it may be displaced through the tissue could be of diagnostic significance and may also have consequences for the validity with which strain images can be interpreted according to the traditional idealizations of elastography. In a previous paper, under the assumption of frictionless boundary conditions, the spatio-temporal behavior of the strain field inside a compressed cylindrical poroelastic sample was predicted (Berry et al. 2006). In this current paper, experimental evidence is provided to confirm these predictions. Finite element modeling was first used to extend the previous predictions to allow for the existence of contact friction between the sample and the compressor plates. Elastographic techniques were then applied to image the time-evolution of the strain inside cylindrical samples of tofu (a suitable poroelastic material) during sustained unconfined compression. The observed experimental strain behavior was found to be consistent with the theoretical predictions. In particular, every sample studied confirmed that reduced values of radial strain advance with time from the curved cylindrical surface inwards towards the axis of symmetry. Furthermore, by fitting the predictions of an analytical model to a time sequence of strain images, parametric images of two quantities, each related to one or more of three poroelastic material constants were produced. The two parametric images depicted the Poisson's ratio (nu(s)) of the solid matrix and the product of the aggregate modulus (H(A)) of the solid matrix with the permeability (k) of the solid matrix to the pore fluid. The means of the pixel values in these images, nu(s) = 0.088 (standard deviation 0.023) and H(A)k = 1.449 (standard deviation 0.269) x 10(-7) m(2) s(-1), were in agreement with values derived from previously published data for tofu (Righetti et al. 2005). The results provide the first experimental detection of the fluid-flow-induced characteristic diffusion-like behavior of the strain in a compressed poroelastic material and allow parameters related to the above material constants to be determined. We conclude that it may eventually be possible to use strain data to detect and measure characteristics of diffusely distributed mobile fluid in tissue spaces that are too small to be imaged directly. PMID:17169699

Berry, Gearóid P; Bamber, Jeffrey C; Miller, Naomi R; Barbone, Paul E; Bush, Nigel L; Armstrong, Cecil G

2006-12-01

218

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.; Görtz, Rüdiger S.; Croner, Roland S.; Neurath, Markus F.; Zopf, Steffen

2014-01-01

219

Single- and Multiple-Track-Location Shear Wave and Acoustic Radiation Force Impulse Imaging: Matched Comparison of Contrast, Contrast-to-Noise Ratio and Resolution.  

PubMed

Acoustic radiation force impulse imaging and shear wave elasticity imaging (SWEI) use the dynamic response of tissue to impulsive mechanical stimulus to characterize local elasticity. A variant of conventional, multiple-track-location SWEI, denoted single-track-location SWEI, offers the promise of creating speckle-free shear wave images. This work compares the three imaging modalities using a high push and track beam density combined acquisition sequence to image inclusions of different sizes and contrasts. Single-track-location SWEI is found to have a significantly higher contrast-to-noise ratio than multiple-track-location SWEI, allowing for operation at higher resolution. Acoustic radiation force impulse imaging and single-track-location SWEI perform similarly in the larger inclusions, with single-track-location SWEI providing better visualization of small targets ?2.5 mm in diameter. The processing of each modality introduces different trade-offs between smoothness and resolution of edges and structures; these are discussed in detail. PMID:25701531

Hollender, Peter J; Rosenzweig, Stephen J; Nightingale, Kathryn R; Trahey, Gregg E

2015-04-01

220

Salmon enumeration in the Fraser River with the dual-frequency identification sonar (DIDSON) acoustic imaging system  

NASA Astrophysics Data System (ADS)

Reliable data on the number of salmon entering tributaries of the Fraser River to spawn (escapement) is needed for Pacific salmon management. Existing escapement techniques are costly and the number of populations requiring assessments has risen because of stock rebuilding efforts. The efficacy of a DIDSON acoustic imaging system for salmon stock assessment was investigated. Sixteen potential sites within the Fraser watershed were surveyed and based on channel morphology, bottom morphology, flow pattern, fish behavior and location relative to spawning grounds, ten sites in six rivers meet the needs of fisheries managers and the DIDSON system for escapement estimates. Fish count data from the DIDSON were compared to data from a counting fence (used as a standard) using regression techniques, resulting in relationships with slopes ranging from 0.98 to 1.02. The precison of DIDSON counts >50 (measured by CV) among three readers was 1.7%. This work supports the conclusion that the DIDSON system can deliver escapement estimates whose accuracy, precision and scientific defensibility is consistent with or better than existing escapment techniques and at a lower operating cost to assessment programs. [Work supported by the Southern Boundary Restoration and Enhancement Fund of the Pacific Salmon Commission.

Holmes, John A.; Cronkite, George; Enzenhofer, Hermann J.

2005-04-01

221

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

222

Photoacoustic diagnosis of burns in rats: two-dimensional photo-acoustic imaging of burned tissue  

NASA Astrophysics Data System (ADS)

We previously reported that for rat burn models, deep dermal burns and deep burns can be well differentiated by measuring the propagation time of the photoacoustic signals originated from the blood in the healthy skin tissue under the damaged tissue layer. However, the diagnosis was based on point measurement in the wound, and therefore site-dependent information on the injuries was not obtained; such information is very important for diagnosis of extended burns. In the present study, we scanned a photoacoustic detector on the wound and constructed two-dimensional (2-D) images of the blood-originated photoacoustic signals for superficial dermal burns (SDB), deep dermal burns (DDB), deep burns (DB), and healthy skins (control) in rats. For each burn model, site-dependent variation of the signal was observed; the variation probably reflects the distribution of blood vessels in the skin tissue. In spite of the variation, clear differentiation was obtained between SDB, DDB, and DB from the 2D images. The images were constructed as a function of post burn time. Temporal signal variation will be also presented.

Yamazaki, Mutsuo; Sato, Shunichi; Saito, Daizo; Okada, Yoshiaki; Kurita, Akira; Kikuchi, Makoto; Ashida, Hiroshi; Obara, Minoru

2003-06-01

223

Acoustic Radiation Force Impulse Imaging for Non-Invasive Assessment of Renal Histopathology in Chronic Kidney Disease  

PubMed Central

Objective To investigate the stiffness values obtained by acoustic radiation force impulse (ARFI) quantification in assessing renal histological fibrosis of chronic kidney disease (CKD). Methods 163 patients with CKD and 32 healthy volunteers were enrolled between June 2013 and April 2014. ARFI quantification, given as shear wave velocity (SWV), was performed to measure renal parenchyma stiffness. Diagnostic performance of ARFI imaging and conventional ultrasound (US) were compared with histologic scores at renal biopsy. Intra- and inter-observer reliability of SWV measurement was analyzed. Results In CKD patients, SWV measurements correlated significantly with pathological parameters (r?=??0.422–?0.511, P<0.001), serum creatinine (r?=??0.503, P<0.001), and glomerular filtration rate (r?=?0.587, P<0.001). The mean SWV in kidneys with severely impaired (histologic score: ?19 points) was significant lower than that mildly impaired (histologic score: ?9 points), moderately impaired (histologic score: 10–18 points), and control groups (all P<0.001). Receiver operating characteristic (ROC) curves analyses indicated that the area under the ROC curve for the diagnosis of renal histological fibrosis using ARFI imaging was superior to these conventional US parameters. Using the optimal cut-off value of 2.65 m/s for the diagnosis of mildly impaired kidneys, 2.50 m/s for moderately impaired kidneys, and 2.33 m/s for severely impaired kidneys, the corresponding area under the ROC curves were 0.735, 0.744, and 0.895, respectively. Intra- and intre-observer agreement of SWV measurements were 0.709 (95% CI: 0.390–0.859, P<0.001) and 0.627 (95% CI: 0.233–0.818, P?=?0.004), respectively. Conclusions ARFI may be an effective tool for evaluating renal histological fibrosis in CKD patients. PMID:25546304

Hu, Qiao; Wang, Xiao-Yan; He, Hong-Guang; Wei, Hai-Ming; Kang, Li-Ke; Qin, Gui-Can

2014-01-01

224

Elasticity of healthy Achilles tendon decreases with the increase of age as determined by acoustic radiation force impulse imaging  

PubMed Central

Aims: The objective of the study was to investigate the value of acoustic radiation force impulse (ARFI) and its application in Achilles tendon elasticity of healthy volunteers. Methods: Bilateral Achilles tendons of 56 healthy individuals were included in the study. The subjects were divided into four age groups. Shear wave velocities (SWVs) of each tendon in the states of relaxation and tension were measured using ARFI technology. We selected the middle section of the Achilles tendon for ARFI measurement. Each Achilles tendon was examined by a musculoskeletal radiologist. Longitudinal images of each tendon were obtained by ultrasound and ARFI elastography. A quantitative assessment of the tissue stiffness was made with virtual touch tissue quantification. Results: Significant differences in SWVs of Achilles tendon were found between any two age groups in the same status (P < 0.05) and between different status in subjects aged 25-35 years (P < 0.05) and 36-45 years (P < 0.05). SWV of Achilles tendon increased with increasing age in both states of relaxation and tension, which was consistent with the histological feature of ageing tendons. However, there were no significant differences between men and women within any group in the same status (P > 0.05) or between different states in subjects aged 46-55 years (P = 0.308) and 56-65 years (P = 0.362). Conclusions: ARFI imaging provides quantitative information about tendon stiffness and represents an excellent supplementary technique to B-mode ultrasound. Furthermore, the elasticity of healthy tendon decreases with increasing age in subjects without disease and long-term heavy load lifting. PMID:25785091

Ruan, Zhengmin; Zhao, Bin; Qi, Hengtao; Zhang, Yuan; Zhang, Feixue; Wu, Mei; Shao, Guangrui

2015-01-01

225

Acoustic Remote Sensing  

NASA Astrophysics Data System (ADS)

Acoustic waves carry information about their source and collect information about their environment as they propagate. This article reviews how these information-carrying and -collecting features of acoustic waves that travel through fluids can be exploited for remote sensing. In nearly all cases, modern acoustic remote sensing involves array-recorded sounds and array signal processing to recover multidimensional results. The application realm for acoustic remote sensing spans an impressive range of signal frequencies (10?2 to 107 Hz) and distances (10?2 to 107 m) and involves biomedical ultrasound imaging, nondestructive evaluation, oil and gas exploration, military systems, and Nuclear Test Ban Treaty monitoring. In the past two decades, approaches have been developed to robustly localize remote sources; remove noise and multipath distortion from recorded signals; and determine the acoustic characteristics of the environment through which the sound waves have traveled, even when the recorded sounds originate from uncooperative sources or are merely ambient noise.

Dowling, David R.; Sabra, Karim G.

2015-01-01

226

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

227

Self-assembly of the first discrete 3d-4f-4f triple-stranded helicate.  

PubMed

The connection of an additional bidentate chelating unit at the extremity of a segmental bis-tridentate ligand in L5 provides an unprecedented sequence of binding sites for the self-assembly of heterometallic 3d-4f triple-stranded helicates. Thorough thermodynamic and structural investigations in acetonitrile show the formation of intricate mixtures of complexes when a single type of metal (3d or 4f) is reacted with L5. However, the situation is greatly simplified when Zn(II) (3d-block) and Lu(III) (4f-block) are simultaneously coordinated to L5, thus leading to only two identified species: the target C(3)-symmetrical trinuclear triple-stranded d-f-f helicate HHH-[ZnLu(2)(L5)(3)](8+) and a tetranuclear double-stranded complex [Zn(2)Lu(2)(L5)(2)](10+). Interestingly, the removal of Zn(II) from the former triple-helical complex has only a minor effect on the coordination of Lu(III), and translational autodiffusion coefficients show a simple reduction of the length of the molecular rigid cylinder from L = 2.7 nm in HHH-[ZnLu(2)(L5)(3)](8+) to L = 2.3 nm in HHH-[Lu(2)(L5)(3)](6+). Finally, the complete thermodynamic picture provides five novel stability macroconstants containing information about short-range (ca. 9 A) and long-range (ca. 18 A) intramolecular intermetallic d-f and f-f interactions. PMID:19499959

Riis-Johannessen, Thomas; Bernardinelli, Gérald; Filinchuk, Yaroslav; Clifford, Sarah; Dalla Favera, Natalia; Piguet, Claude

2009-06-15

228

Phase conjugation of the second harmonic of a focused ultrasound beam as a method for improving C-scan acoustical imaging in nonlinear inhomogeneous media  

NASA Astrophysics Data System (ADS)

Acoustical imaging in complex media (e.g., biological tissue) can be affected by phase aberrations introduced in a wave during propagation. Wave phase conjugation (WPC) of ultrasound is known for its ability to compensate for phase distortions due to inhomogeneity of the propagation medium, and it can be used for improvement of acoustical imaging under these conditions. In a nonlinear medium harmonics are generated during propagation of an intense beam of ultrasound, and this principle is used in tissue harmonic imaging. The parametric method of WPC permits phase conjugation of a selected frequency component of the probe beam. In this way the peculiarities of WPC can be combined with advantages of harmonic imaging. Automated WPC-focusing of the conjugated second-harmonic component of a focused nonlinear probe beam is studied experimentally and theoretically for the case of a homogeneous medium, and experimentally for a medium with pseudo-random inhomogeneities. The generated conjugate wave can also be sufficiently intense to generate higher-order harmonics, which display enhanced focusing. Improvement of a C-scan harmonic imaging system operating in an inhomogeneous medium is provided as an example.

Krutyansky, Leonid M.; Brysev, Andrew P.; Klopotov, Roman V.; Pernod, Philippe J.; Preobrazhensky, Vladimir L.; Yan, Xiang; Hamilton, Mark F.

2003-10-01

229

High contrast air-coupled acoustic imaging with zero group velocity lamb modes.  

PubMed

The well known zero in the group velocity of the first-order symmetric (S1) plate wave mode has been exploited in air-coupled ultrasonic imaging to obtain significantly higher sensitivity than can be achieved in conventional air-coupled scanning. At the zero group velocity point at the frequency minimum of the S1 mode, a broad range of wavenumbers couple into the first-order symmetric mode at nearly a constant frequency, greatly enhancing transmission at that frequency. Coupled energy remains localized near the coupling point because the group velocity is zero. We excite the mode with a broadband, focussing, air-coupled transducer at the frequency of the zero group velocity point in the S1 mode. By exploiting the efficient coupling at the zero group velocity frequency, we have easily imaged a single layer of Scotch tape attached to a 6.4-mm thick Plexiglas plate and 3.2-mm Teflon inserts in a composite laminate. PMID:15047413

Holland, Stephen D; Chimenti, D E

2004-04-01

230

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

231

Time domain simulation of nonlinear acoustic beams generated by rectangular pistons with application to harmonic imaging  

NASA Astrophysics Data System (ADS)

A time-domain numerical code (the so-called Texas code) that solves the Khokhlov-Zabolotskaya-Kuznetsov (KZK) equation has been extended from an axis-symmetric coordinate system to a three-dimensional (3D) Cartesian coordinate system. The code accounts for diffraction (in the parabolic approximation), nonlinearity and absorption and dispersion associated with thermoviscous and relaxation processes. The 3D time domain code was shown to be in agreement with benchmark solutions for circular and rectangular sources, focused and unfocused beams, and linear and nonlinear propagation. The 3D code was used to model the nonlinear propagation of diagnostic ultrasound pulses through tissue. The prediction of the second-harmonic field was sensitive to the choice of frequency-dependent absorption: a frequency squared f2 dependence produced a second-harmonic field which peaked closer to the transducer and had a lower amplitude than that computed for an f1.1 dependence. In comparing spatial maps of the harmonics we found that the second harmonic had dramatically reduced amplitude in the near field and also lower amplitude side lobes in the focal region than the fundamental. These findings were consistent for both uniform and apodized sources and could be contributing factors in the improved imaging reported with clinical scanners using tissue harmonic imaging. .

Yang, Xinmai; Cleveland, Robin O.

2005-01-01

232

Web Ecology: Recycling HTML pages as XML documents using W4F  

E-print Network

Web Ecology: Recycling HTML pages as XML documents using W4F Arnaud Sahuguet Department of Computer sources. Some key features of W4F are an expres­ sive language to extract information from HTML pages, we demonstrate how to use W4F to cre­ ate XML gateways, that serve transparently and on­the­fly HTML

Pennsylvania, University of

233

Web Ecology: Recycling HTML pages as XML documents using W4F  

E-print Network

Web Ecology: Recycling HTML pages as XML documents using W4F Arnaud Sahuguet Department of Computer key features of W4F are an expres- sive language to extract information from HTML pages, we demonstrate how to use W4F to cre- ate XML gateways, that serve transparently and on-the- y HTML

Pennsylvania, University of

234

Acoustic Radiation Force Impulse Imaging: A New Tool for the Diagnosis of Papillary Thyroid Microcarcinoma  

PubMed Central

Purpose. To evaluate the diagnostic performance of ARFI imaging in differentiating between benign and malignant thyroid nodules <1?cm. Materials and Methods. 173 pathologically proven thyroid nodules (77 benign, 96 malignant) in 157 patients were included in this study. Receiver-operating characteristic curve (ROC) analyses were performed to assess the diagnostic performance of conventional ultrasound (US) and ARFI imaging in papillary thyroid microcarcinoma (PTMC). The independent risk factors for predicting PTMC were evaluated. Results. The mean SWV value of benign and malignant thyroid nodules were 2.57 ± 0.79?m/s (range: 0.90–4.92?m/s) and 3.88 ± 2.24?m/s (range: 1.49–9.00?m/s) (P = 0.000). Az for VTI elastography score was higher than that for hypoechoic, absence of halo sign, and type III vascularity (P < 0.05). The optimal cut-offs for VTI elastography score and SWV were score 4 and 3.10?m/s. Gender, hypoechoic, taller than wide, VTI elastography score ? 4, and SWV > 3.10?m/s had been found to be independent risk factors for predicting PTMC. Conclusion. ARFI elastography can provide elasticity information of PTMC quantitatively (VTQ) and directly reflects the overall elastic properties (VTI). Gender, hypoechogenicity, taller than wide, VTI elastography score ? 4, and SWV > 3.10?m/s are independent risk factors for predicting PTMC. ARFI elastography seems to be a new tool for the diagnosis of PTMC. PMID:25045673

Zhang, Yi-Feng; Xu, Jun-Mei; Zhang, Jing; Liu, Lin-Na; Xu, Xiao-Hong

2014-01-01

235

A cyano-bridged dinuclear 4f-3d array.  

PubMed

A cyano-bridged bimetallic 4f-3d complex, triaqua-1 kappa(3)O-mu-cyano-1:2 kappa(2)N:C-pentacyano-2 kappa(5)C-tetrakis(2-pyrrolidone-1 kappa O)chromium(III)dysprosium(III) dihydrate, [CrDy(C(4)H(7)NO)(4)(CN)(6)(H(2)O)(3)] x 2H(2)O, has been prepared and characterized by X-ray crystallographic analysis. The structure consists of a neutral cyano-bridged Dy-Cr dimer. A hydrogen-bonded three-dimensional architecture is formed through N[bond]H...O, O[bond]H...N and O[bond]H...O hydrogen bonds. PMID:12050411

Kou, Hui-Zhong; Gao, Song; Wang, Ru-Ji

2002-06-01

236

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

237

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

238

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 ...

239

Numerical Acoustics  

NASA Astrophysics Data System (ADS)

Numerical acoustics - horrible concept! It is not a question of number crunching, it is an issue of constructively translating the knowledge in the branch of classical physics - acoustics - into quantitative result.

Petersson, Björn A. T.

240

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

241

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

242

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

243

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-to-tissue 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 D; Rojas, Juan D; Martin, K Heath; Shelton, Sarah E; Dayton, Paul A

2014-10-01

244

Structural relationships among LiNaMg[PO4]F and Na2M[PO4]F (M = Mn-Ni, and Mg), and the magnetic structure of LiNaNi[PO4]F.  

PubMed

The new compound LiNaMg[PO4]F has been synthesized by a wet chemical reaction route. Its crystal structure was determined from single-crystal X-ray diffraction data. LiNaMg[PO4]F crystallizes with the monoclinic pseudomerohedrally twinned LiNaNi[PO4]F structure, space group P2(1)/c, a = 6.772(4), b = 11.154(6), c = 5.021(3) Å, ? = 90.00(1)° and Z = 4. The structure contains [MgO3F]n chains made up of zigzag edge-sharing MgO4F2 octahedra. These chains are interlinked by PO4 tetrahedra forming 2D-Mg[PO4]F layers. The alkali metal atoms are well ordered in between these layers over two atomic positions. The use of group-subgroup transformation schemes in the Bärnighausen formalism enabled us to determine precise phase transition mechanisms from LiNaNi[PO4]F- to Na2M[PO4]F-type structures (M = Mn-Ni, and Mg) (see video clip 1 and 2). The crystal and magnetic structure and properties of the parent LiNaNi[PO4]F phase were also studied by magnetometry and neutron powder diffraction. Despite the rather long interlayer distance, d(min)(Ni(+2)-Ni(+2)) ~ 6.8 Å, the material develops a long-range magnetic order below 5 K. The magnetic structure can be viewed as antiferromagnetically coupled ferromagnetic layers with moments parallel to the b-axis. PMID:24276233

Ben Yahia, Hamdi; Shikano, Masahiro; Kobayashi, Hironori; Avdeev, Maxim; Liu, Samuel; Ling, Chris D

2014-02-01

245

Metastatic signet ring cell carcinoma presenting as a thyroid diffuse involvement: report of a case studied with Q-elastographic and acoustic radiation force impulse imaging features.  

PubMed

Metastatic carcinomas to the thyroid are rare in daily clinical practice. However, when encountered they represent a diagnostic challenge, since it is difficult to distinguish them from primary thyroid lesions, especially when occurring in patients with occult malignant history. Nevertheless, it is critical to differentiate a metastatic tumor from primary thyroid lesions, as the clinical management and the prognosis are different for the two entities. More recently, elastosonography opened new possibilities to ultrasound in different fields, such as thyroid nodule differentiation. Herein, we report a case of metastatic signet ring cell carcinoma to the thyroid studied with quantitative elastography and acoustic radiation force impulse imaging. PMID:24158087

Cantisani, Vito; Lodise, Pietro; Di Cosimo, Carla; Metere, Alessio; Chiesa, Carlo; Mancuso, Ester; Di Segni, Mattia; Fioravanti, Cristina; Di Rocco, Giorgio; Bernieri, Maria Giulia; Ricci, Paolo; Fierro, Giovanni; Giacomelli, Laura; Orsogna, Nicola; Redler, Adriano

2013-01-01

246

Accessing 4f-states in single-molecule spintronics  

NASA Astrophysics Data System (ADS)

Magnetic molecules are potential functional units for molecular and supramolecular spintronic devices. However, their magnetic and electronic properties depend critically on their interaction with metallic electrodes. Charge transfer and hybridization modify the electronic structure and thereby influence or even quench the molecular magnetic moment. Yet, detection and manipulation of the molecular spin state by means of charge transport, that is, spintronic functionality, mandates a certain level of hybridization of the magnetic orbitals with electrode states. Here we show how a judicious choice of the molecular spin centres determines these critical molecule-electrode contact characteristics. In contrast to late lanthanide analogues, the 4f-orbitals of single bis(phthalocyaninato)-neodymium(III) molecules adsorbed on Cu(100) can be directly accessed by scanning tunnelling microscopy. Hence, they contribute to charge transport, whereas their magnetic moment is sustained as evident from comparing spectroscopic data with ab initio calculations. Our results showcase how tailoring molecular orbitals can yield all-electrically controlled spintronic device concepts.

Fahrendorf, Sarah; Atodiresei, Nicolae; Besson, Claire; Caciuc, Vasile; Matthes, Frank; Blügel, Stefan; Kögerler, Paul; Bürgler, Daniel E.; Schneider, Claus M.

2013-09-01

247

Atmospheric chemistry of C4F9OC2H5 (HFE-7200), C4F9OCH3 (HFE-7100),  

E-print Network

, Reading RG6 6AD, UK Abstract The atmospheric chemistry of several gases used in industrial applications, CAtmospheric chemistry of C4F9OC2H5 (HFE-7200), C4F9OCH3 (HFE-7100), C3F7OCH3 (HFE-7000) and C3F7CH212547A3A37A?E472C43&AD'A>794E6 >794E6;CA27C725AD33833CADE64E7 #12;--1-- Atmospheric chemistry of C4F9OC2

Wirosoetisno, Djoko

248

Imaging and quantitative data acquisition of biological cell walls with Atomic Force Microscopy and Scanning Acoustic Microscopy  

SciTech Connect

This chapter demonstrates the feasibility of Atomic Force Microscopy (AFM) and High Frequency Scanning Acoustic Microscopy (HF-SAM) as tools to characterize biological tissues. Both the AFM and the SAM have shown to provide imaging (with different resolution) and quantitative elasticity measuring abilities. Plant cell walls with minimal disturbance and under conditions of their native state have been examined with these two kinds of microscopy. After descriptions of both the SAM and AFM, their special features and the typical sample preparation is discussed. The sample preparation is focused here on epidermal peels of onion scales and celery epidermis cells which were sectioned for the AFM to visualize the inner surface (closest to the plasma membrane) of the outer epidermal wall. The nm-wide cellulose microfibrils orientation and multilayer structure were clearly observed. The microfibril orientation and alignment tend to be more organized in older scales compared with younger scales. The onion epidermis cell wall was also used as a test analog to study cell wall elasticity by the AFM nanoindentation and the SAM V(z) feature. The novelty in this work was to demonstrate the capability of these two techniques to analyze isolated, single layered plant cell walls in their natural state. AFM nanoindentation was also used to probe the effects of Ethylenediaminetetraacetic acid (EDTA), and calcium ion treatment to modify pectin networks in cell walls. The results suggest a significant modulus increase in the calcium ion treatment and a slight decrease in EDTA treatment. To complement the AFM measurements, the HF-SAM was used to obtain the V(z) signatures of the onion epidermis. These measurements were focused on documenting the effect of pectinase enzyme treatment. The results indicate a significant change in the V(z) signature curves with time into the enzyme treatment. Thus AFM and HF-SAM open the door to a systematic nondestructive structure and mechanical property study of complex biological cell walls. A unique feature of this approach is that both microscopes allow the biological samples to be examined in their natural fluid (water) environment.

Tittmann, B. R. [Penn State; Xi, X. [Penn State

2014-09-01

249

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

250

Revealing, identifying, and assessing flaws in operating equipment by the acoustic emission image recognition method under strong background noise condition  

Microsoft Academic Search

The analysis has shown that high pressure and high temperature piping in fossil and nuclear power plants suffer from unexpected and rarely predictable failures. To guarantee operational safety and to prevent failures authors have performed the complex investigations and have created Quantitative Acoustic Emission NDI technology for revealing, identifying and assessing flaws in equipment operated under strong background noise condition.

Gregory Muravin; Boris Muravin; Ludmila Lezvisky

2004-01-01

251

Effectiveness of imaging seismic attenuation using visco-acoustic full waveform tomography: Examples from the Seattle Fault Zone and Northern Perth Basin  

NASA Astrophysics Data System (ADS)

Attenuation characterizes the decrease in amplitude of seismic waves as they propagate away from the source. A seismic wave propagating in the subsurface will suffer from two types of attenuation: Intrinsic attenuation and scattering attenuation. Scattering attenuation is due to small scale heterogeneity in the subsurface, whereas intrinsic attenuation arises from inelastic rock properties. Intrinsic attenuation can provide key information about the subsurface, which can be of value to the mining as well as the oil and gas industry. However, accurate imaging of intrinsic seismic attenuation using visco-acoustic full-waveform tomography is not straight forward. Attenuation models recovered by visco-acoustic waveform tomography are often contain contaminated by scattering effects as well as elastic mode conversion artefacts due to the inability of the visco-acoustic approximation to perfectly predict the amplitude of visco-elastic field data. The effect of scattering can be reduced if a velocity model with a high resolution is used. This usually necessitates a two-step inversion approach consisting of first recovering the velocity model and later, the attenuation model. In this study, we present a specific preconditioning of the data based on matching the amplitude variation with offset (AVO) of the field and modelled visco-acoustic data, and a specific inversion approach based on a sequential recovering of the seismic velocity and attenuation models using the visco-acoustic approximation. Our purpose is to improve the quality of the recovered attenuation model by decoupling the reconstruction of velocity and attenuation, thus reducing artefacts. We apply the method to two different areas: The Seattle Fault Zone in Puget Sound in the northwestern USA, using marine seismic reflection data from the Seismic Hazards investigation in Puget Sound (SHIPS) survey collected in 1998, and the Allanooka area within the Northern Perth Basin using high resolution seismic reflection data collected in 2010 for groundwater modelling. In the Allanooka area, we investigate the use of joint inversion of controlled source electromagnetic (CSEM) and seismic data to obtain a more accurate starting velocity model for full-waveform tomography, where the starting usable frequency for waveform tomography is relatively large. We assess the reliability of the results with a set of visco-elastic modelling tests.

Takam Takougang, E.; Calvert, A. J.

2012-12-01

252

Topological Acoustics  

NASA Astrophysics Data System (ADS)

The manipulation of acoustic wave propagation in fluids has numerous applications, including some in everyday life. Acoustic technologies frequently develop in tandem with optics, using shared concepts such as waveguiding and metamedia. It is thus noteworthy that an entirely novel class of electromagnetic waves, known as "topological edge states," has recently been demonstrated. These are inspired by the electronic edge states occurring in topological insulators, and possess a striking and technologically promising property: the ability to travel in a single direction along a surface without backscattering, regardless of the existence of defects or disorder. Here, we develop an analogous theory of topological fluid acoustics, and propose a scheme for realizing topological edge states in an acoustic structure containing circulating fluids. The phenomenon of disorder-free one-way sound propagation, which does not occur in ordinary acoustic devices, may have novel applications for acoustic isolators, modulators, and transducers.

Yang, Zhaoju; Gao, Fei; Shi, Xihang; Lin, Xiao; Gao, Zhen; Chong, Yidong; Zhang, Baile

2015-03-01

253

Topological acoustics.  

PubMed

The manipulation of acoustic wave propagation in fluids has numerous applications, including some in everyday life. Acoustic technologies frequently develop in tandem with optics, using shared concepts such as waveguiding and metamedia. It is thus noteworthy that an entirely novel class of electromagnetic waves, known as "topological edge states," has recently been demonstrated. These are inspired by the electronic edge states occurring in topological insulators, and possess a striking and technologically promising property: the ability to travel in a single direction along a surface without backscattering, regardless of the existence of defects or disorder. Here, we develop an analogous theory of topological fluid acoustics, and propose a scheme for realizing topological edge states in an acoustic structure containing circulating fluids. The phenomenon of disorder-free one-way sound propagation, which does not occur in ordinary acoustic devices, may have novel applications for acoustic isolators, modulators, and transducers. PMID:25839273

Yang, Zhaoju; Gao, Fei; Shi, Xihang; Lin, Xiao; Gao, Zhen; Chong, Yidong; Zhang, Baile

2015-03-20

254

E4F1 deficiency results in oxidative stress-mediated cell death of leukemic cells  

E-print Network

cell lines, E4F1 inactivation resulted in mitochondrial defects and increased ROS levels that triggered leukemic cell lines. Interestingly, these defects were detected in HS cells but not in normal primaryE4F1 deficiency results in oxidative stress-mediated cell death of leukemic cells Elodie Hatchi1

Boyer, Edmond

255

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

256

Comparison of Scanning Acoustic Microscopy and Histology Images in Characterizing Surface Irregularities Among Engineered Human Oral Mucosal Tissues  

Microsoft Academic Search

Acoustic microscopy was used to monitor an ex vivo produced oral mucosal equivalent (EVPOME) developed on acellular cadaveric dermis (AlloDerm®). As seeded cells adhered and grew, they filled in and smoothed out the surface irregularities, followed by the production of a keratinized protective outermost layer. If noninvasive in vitro ultrasonic monitoring of these cellular changes could be developed, then tissue cultivation could

Frank Winterroth; Kyle W. Hollman; Shiuhyang Kuo; Kenji Izumi; Stephen E. Feinberg; Scott J. Hollister; J. Brian Fowlkes

2011-01-01

257

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

258

Subsurface 3D high-resolution fault imaging: An example from the Kamishiro fault in Lake Aoki obtained by acoustic exploration, central Japan  

NASA Astrophysics Data System (ADS)

To visualize 3D inland geologic structure associated with active faulting, one uses high-cost multiple seismic reflection profiles. Here we fortunately face an unusual case: a large lake across one of the most active faults allows us to use acoustic exploration to visualize the subsurface deformation as the 3D high-resolution images. We investigated the Kamishiro fault, which is a northern part of the Itoigawa-Shizuoka tectonic line active fault system (ISTL), to reveal its Holocene activity. Lake Aoki, which is a natural dam reservoir bonded by an old landslide mass located in the city of Omachi, Nagano Prefecture, hides a 30-meter-high N-S striking fault scarp. On the lake, we employed a 10-KHz acoustic sonar equipment which maximum resolution for the images is 5 cm and which maximum depth of acoustic penetration is 20 m. We cruised the 51 transverse lines which interval and length are 25 m and 900 m on average. The entire profile set covers ~ 1.5 km x 1.5 km area and provides us not only the detailed fault traces ever mapped but also multiple paleoseismic event horizons in the deformed lacustrine strata. We found three major fault traces (F1, F2, and F3 from west to east), one of which (F2) corresponds to the previously mapped the N-S striking fault scarp that separates the major basin (west) and shallow sub-basin (east). A newly identified fault (F1) coincides with a steep sub-lake cliff that bounds the western margin of the major basin. These two faults (F1 and F2) are bifurcated from the north coast of the lake to the south and bear the major basin as a pull-apart basin structure. On the sub-basin, strata under a 500-meter-long topographic bulge also show evidence of the recent reverse faulting. Such an imaged complex fault system that strike-slip faults and a reverse fault coexist would cast a new view over the common knowledge of tectonic framework for the future earthquake potential on the ISTL.

Haraguchi, T.; Yoshinaga, Y.; Toda, S.

2006-12-01

259

Preparation, Structure, and Properties of V 2GeO 4F 2—Chains of VO 4F 2 Octahedra in the First V(III) Metallate Fluoride  

NASA Astrophysics Data System (ADS)

Powder samples of the new oxide fluoride V 2GeO 4F 2 have been obtained by the reaction of appropriate amounts V 2O 3, VF 3, and GeO 2 at 700°C for 18 h in an argon-filled sealed platinum tube. V 2GeO 4F 2 crystallizes in the space group Pnma with a=9.336(1), b=8.898 (1), and c=4.912 (1) Å. The structure has been refined from X-ray powder diffraction data using the Rietveld method ( Rint=5.5% and Rp=9.8%). The structure of V 2GeO 4F 2 exhibits close packed layers of the anions with an ordering of O and F. The characteristic building units are discrete GeO 4 tetrahedra with Ge-O distances of 1.75-1.80 Å. The V are coordinated by four O and two F to form VO 4F 2 octahedra connected via two common edges to give zigzag chains. These chains are linked via corners to form a three-dimensional network. The temperature dependence of the magnetic susceptibility of V 2GeO 4F 2 indicates antiferromagnetic correlations.

Achary, S. N.; Tyagi, A. K.; Köhler, J.

2002-04-01

260

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.

261

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

262

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

263

Plant cap-binding complexes eukaryotic initiation factors eIF4F and eIFISO4F: molecular specificity of subunit binding.  

PubMed

The initiation of translation in eukaryotes requires a suite of eIFs that include the cap-binding complex, eIF4F. eIF4F is comprised of the subunits eIF4G and eIF4E and often the helicase, eIF4A. The eIF4G subunit serves as an assembly point for other initiation factors, whereas eIF4E binds to the 7-methyl guanosine cap of mRNA. Plants have an isozyme form of eIF4F (eIFiso4F) with comparable subunits, eIFiso4E and eIFiso4G. Plant eIF4A is very loosely associated with the plant cap-binding complexes. The specificity of interaction of the individual subunits of the two complexes was previously unknown. To address this issue, mixed complexes (eIF4E-eIFiso4G or eIFiso4E-eIF4G) were expressed and purified from Escherichia coli for biochemical analysis. The activity of the mixed complexes in in vitro translation assays correlated with the large subunit of the respective correct complex. These results suggest that the eIF4G or eIFiso4G subunits influence translational efficiency more than the cap-binding subunits. The translation assays also showed varying responses of the mRNA templates to eIF4F or eIFiso4F, suggesting that some level of mRNA discrimination is possible. The dissociation constants for the correct complexes have K(D) values in the subnanomolar range, whereas the mixed complexes were found to have K(D) values in the ?10 nm range. Displacement assays showed that the correct binding partner readily displaces the incorrect binding partner in a manner consistent with the difference in K(D) values. These results show molecular specificity for the formation of plant eIF4F and eIFiso4F complexes and suggest a role in mRNA discrimination during initiation of translation. PMID:21965660

Mayberry, Laura K; Allen, M Leah; Nitka, Kelley R; Campbell, Lara; Murphy, Patricia A; Browning, Karen S

2011-12-01

264

4-D imaging of seepage in earthen embankments with time-lapse inversion of self-potential data constrained by acoustic emissions localization  

NASA Astrophysics Data System (ADS)

New methods are required to combine the information contained in the passive electrical and seismic signals to detect, localize and monitor hydromechanical disturbances in porous media. We propose a field experiment showing how passive seismic and electrical data can be combined together to detect a preferential flow path associated with internal erosion in a Earth dam. Continuous passive seismic and electrical (self-potential) monitoring data were recorded during a 7-d full-scale levee (earthen embankment) failure test, conducted in Booneschans, Netherlands in 2012. Spatially coherent acoustic emissions events and the development of a self-potential anomaly, associated with induced concentrated seepage and internal erosion phenomena, were identified and imaged near the downstream toe of the embankment, in an area that subsequently developed a series of concentrated water flows and sand boils, and where liquefaction of the embankment toe eventually developed. We present a new 4-D grid-search algorithm for acoustic emissions localization in both time and space, and the application of the localization results to add spatially varying constraints to time-lapse 3-D modelling of self-potential data in the terms of source current localization. Seismic signal localization results are utilized to build a set of time-invariant yet spatially varying model weights used for the inversion of the self-potential data. Results from the combination of these two passive techniques show results that are more consistent in terms of focused ground water flow with respect to visual observation on the embankment. This approach to geophysical monitoring of earthen embankments provides an improved approach for early detection and imaging of the development of embankment defects associated with concentrated seepage and internal erosion phenomena. The same approach can be used to detect various types of hydromechanical disturbances at larger scales.

Rittgers, J. B.; Revil, A.; Planes, T.; Mooney, M. A.; Koelewijn, A. R.

2015-02-01

265

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

266

Radial integrals 4f and nephelauxetic effect of Nd3+ in crystals  

NASA Astrophysics Data System (ADS)

The radial expectation values 4f, k = 2, 4, 6, for oxygen- or halogen- coordinated Nd3+ ions in 25 crystals have been obtained from experimental Slater parameter shifts ?Fk = Fk (free ion) - Fk (crystal) by means of the dielectric screening model. The 4f values found by this new approach are compatible with those computed by relativistic 4f wave functions. The nephelauxetic ratios ?k in respect to the free ion Nd IV have been also determined and related to covalency and bonding parameters.

Petrov, D.; Angelov, B.

2014-01-01

267

Radial integrals 4f and nephelauxetic effect of Nd3+ in crystals.  

PubMed

The radial expectation values 4f,k=2, 4, 6, for oxygen- or halogen- coordinated Nd(3+) ions in 25 crystals have been obtained from experimental Slater parameter shifts ?Fk=Fk (free ion) - Fk (crystal) by means of the dielectric screening model. The 4f values found by this new approach are compatible with those computed by relativistic 4f wave functions. The nephelauxetic ratios ?k in respect to the free ion Nd IV have been also determined and related to covalency and bonding parameters. PMID:24051290

Petrov, D; Angelov, B

2014-01-24

268

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.

269

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

270

Revealing, identifying, and assessing flaws in operating equipment by the acoustic emission image recognition method under strong background noise condition  

NASA Astrophysics Data System (ADS)

The analysis has shown that high pressure and high temperature piping in fossil and nuclear power plants suffer from unexpected and rarely predictable failures. To guarantee operational safety and to prevent failures authors have performed the complex investigations and have created Quantitative Acoustic Emission NDI technology for revealing, identifying and assessing flaws in equipment operated under strong background noise condition. These enabled: Overall inspection of the piping operated under stress, temperature, pressure, steam flow and loading, variation. Locating suspected zones and zones of flaw development with low J-integral value and the great variation of the dynamic range of flaws danger level. Identification of flaw types and their danger level. Detection of defective components in service prior to shut down. The continuous and the burst Acoustic Emission (AE) were used in combination as an information tool. As result, the significant number of flaws such as creep at stage 3a-3b, closed-edge micro-cracks, systems of randomly dispersed pores and inclusions, plastic deformation development around them, or/and individual micro-cracking were revealed, identified and assessed in 50 operating high energy piping. The findings and assessing flaw danger level obtained by QAE NDI were confirmed by independent NDI methods as TOFD, X-ray, replication, metallurgical investigations, etc. The findings and assessing flaw danger level obtained by QAE NDI were confirmed by independent NDI methods such as TOFD, X-ray, replication, metallurgical investigations, etc

Muravin, Gregory; Muravin, Boris; Lezvisky, Ludmila

2004-05-01

271

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.

272

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

273

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

274

The sounds of nanoscience: acoustic STM analogues  

NASA Astrophysics Data System (ADS)

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 an acoustic analogue of a quantum corral. The acoustic models foster reflections about the nature of STM images and elucidate the productive tension of imaging and imagining matter at the nanoscale.

Euler, Manfred

2013-09-01

275

Acoustic microscope based on magneto-elastic wave phase conjugator  

NASA Astrophysics Data System (ADS)

Acoustic C-scan imaging (acoustic microscopy) by means of supercritical parametric wave phase conjugation (WPC) is studied experimentally. A phase conjugator based on a magneto-acoustic active material is used for compensating phase distortions introduced by solid and polymer aberration layers covering objects (electronic integrated circuits as examples). Improvement of images is demonstrated on an acoustic microscope, operating at a frequency of 10 MHz.

Brysev, A.; Krutyansky, L.; Pernod, P.; Preobrazhensky, V.

2000-05-01

276

4f--5d transitions and polarizability of rare earth ions  

SciTech Connect

Simple and fairly general expressions for the contribution of 4f--5d transitions to the electric polarizability tensor of rare earth ions are derived on the basis of angular momentum theory. These expressions permit a quantitative calculation of the role of the 4f sublattice in the effects of circular and linear birefringence and dichroism. It is shown that the maximum contribution of 4f ions to the birefringence, including magnetic birefringence, may be as high as approx.10/sup -2/ when lambdaapprox.0.6 ..mu..m. As an illustration, a quantitative calculation of the contribution of 4f--5d transitions to the birefringence of orthoferrites DyFeO/sub 3/ and ErFeO/sub 3/ is carried out.

Moskvin, A.S.; Pleshchev, V.M.

1988-04-01

277

4f and 5d Levels of Ce3+ in D2 8-fold oxygen coordination  

NASA Astrophysics Data System (ADS)

The effects of the first coordination shell geometry of the trivalent Cerium ion (Ce3+) on its 4f and 5d levels in Ce-doped oxides with a D2 8-fold site, like garnets, are studied with embedded cluster, wave function based ab initio methods. The only deformations of a D2 CeO8 moiety that are found to shift the lowest 4f ? 5d transition to the red (longer wavelengths) are the symmetric Ce-O bond compression and the tetragonal symmetric bond bending. In a first approximation, the lowest 5d level of Ce3+ in garnets can be understood as resulting from the cubic Eg level with a strong Eg × eg Jahn-Teller coupling. These results are analyzed in terms of 5d - 4f centroid energy differences and ligand field stabilizations. The splittings of the upper 5d levels and of the 4f levels are also discussed.

Seijo, Luis; Barandiarán, Zoila

2013-09-01

278

48 CFR 47.305-4 - F.o.b. destination solicitations.  

Code of Federal Regulations, 2010 CFR

... 2010-10-01 2010-10-01 false F.o.b. destination solicitations. 47...Transportation in Supply Contracts 47.305-4 F.o.b. destination solicitations. (a) When preparing f.o.b destination solicitations, the...

2010-10-01

279

Construction of nitronyl nitroxide-based 3d-4f clusters: structure and magnetism.  

PubMed

Three unprecedented nitronyl nitroxide radical-bridged 3d-4f clusters, [Ln2 Cu2 (hfac)10 (NIT-3py)2 (H2 O)2 ](Ln(III) =Y, Gd, Dy), have been obtained from the self-assembly of Ln(hfac)3 , Cu(hfac)2 , and the radical ligand. The Dy complex shows a slow relaxation of magnetization, representing the first nitronyl nitroxide radical-based 3d-4f cluster with single-molecule magnet behavior. PMID:25393727

Wang, Xiu-Feng; Hu, Peng; Li, Yun-Gai; Li, Li-Cun

2015-02-01

280

4f photoionization and subsequent Auger decay in atomic Pb: Relativistic effects  

SciTech Connect

High-resolution 4f photoelectron and subsequent Auger-electron spectra have been measured from free Pb atoms using synchrotron radiation. The fine structure of the spectra has been investigated theoretically by calculating the energies and intensities for 4f photoionization and Auger decay processes using the multiconfigurational Dirac-Fock approach. The role of the relativistic effects in the ground and singly and doubly ionized states has been studied on the basis of computed results and their comparison with experiment.

Patanen, M.; Kantia, T.; Heinaesmaeki, S.; Aksela, S.; Aksela, H. [Department of Physics, University of Oulu, P.O. Box 3000, FIN-90014 University of Oulu (Finland); Urpelainen, S. [Max-lab, Lund University, Box 118, SE-22100 Lund (Sweden)

2011-05-15

281

Ce 4f orbital coupling to transition-metal band structure: An ion-implantation study  

Microsoft Academic Search

Using ion implantation, we have prepared atomically dispersed alloys of Ce in almost all of the 3d, 4d, and 5d transition metals. We have measured the response of the implanted Ce 4f orbital to its host transition-metal environment via the Ce L3 valence-state determination method. The close correspondence between the Ce 4f orbital occupancy and the host transition-metal d-band electronic

F. Lu; N. Stoffel; R. A. Neifeld; S. Gunapala; M. Croft; M. L. den Boer

1988-01-01

282

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

283

Inhibitor of eukaryotic initiation factor 4F activity in unfertilized sea urchin eggs.  

PubMed Central

Extracts from unfertilized sea urchin eggs contain an inhibitor of translation that inhibits protein synthesis in cell-free translation systems from sea urchin embryos or rabbit reticulocytes. The inhibitory effects of egg extracts can be reversed by the addition of mammalian eukaryotic initiation factor 4F (eIF-4F) in both sea urchin embryo and reticulocyte systems, suggesting that the inhibitor inactivates this initiation factor. The accumulated data suggest that the ability of eIF-4F to recycle may be compromised. The addition of eIF-4F to cell-free translation systems from unfertilized sea urchin eggs also stimulates protein synthesis. However, the stimulation does not increase protein synthetic activity in the egg cell-free translation system to the levels observed in those produced from 2-hr embryos. This suggests that, although the unfertilized egg contains an inhibitor of eIF-4F and reduced levels of eIF-4F activity, inactivation of this component is only one of the factors involved in the low rate of maternal mRNA utilization found prior to fertilization. PMID:3476952

Huang, W I; Hansen, L J; Merrick, W C; Jagus, R

1987-01-01

284

Targeting the eIF4F translation initiation complex: a critical nexus for cancer development.  

PubMed

Elevated protein synthesis is an important feature of many cancer cells and often arises as a consequence of increased signaling flux channeled to eukaryotic initiation factor 4F (eIF4F), the key regulator of the mRNA-ribosome recruitment phase of translation initiation. In many cellular and preclinical models of cancer, eIF4F deregulation results in changes in translational efficiency of specific mRNA classes. Importantly, many of these mRNAs code for proteins that potently regulate critical cellular processes, such as cell growth and proliferation, enhanced cell survival and cell migration that ultimately impinge on several hallmarks of cancer, including increased angiogenesis, deregulated growth control, enhanced cellular survival, epithelial-to-mesenchymal transition, invasion, and metastasis. By being positioned as the molecular nexus downstream of key oncogenic signaling pathways (e.g., Ras, PI3K/AKT/TOR, and MYC), eIF4F serves as a direct link between important steps in cancer development and translation initiation. Identification of mRNAs particularly responsive to elevated eIF4F activity that typifies tumorigenesis underscores the critical role of eIF4F in cancer and raises the exciting possibility of developing new-in-class small molecules targeting translation initiation as antineoplastic agents. PMID:25593033

Pelletier, Jerry; Graff, Jeremy; Ruggero, Davide; Sonenberg, Nahum

2015-01-15

285

Translation initiation factor eIF4F modifies the dexamethasone response in multiple myeloma  

PubMed Central

Enhanced protein synthesis capacity is associated with increased tumor cell survival, proliferation, and resistance to chemotherapy. Cancers like multiple myeloma (MM), which display elevated activity in key translation regulatory nodes, such as the PI3K/mammalian target of rapamycin and MYC-eukaryotic initiation factor (eIF) 4E pathways, are predicted to be particularly sensitive to therapeutic strategies that target this process. To identify novel vulnerabilities in MM, we undertook a focused RNAi screen in which components of the translation apparatus were targeted. Our screen was designed to identify synthetic lethal relationships between translation factors or regulators and dexamethasone (DEX), a corticosteroid used as frontline therapy in this disease. We find that suppression of all three subunits of the eIF4F cap-binding complex synergizes with DEX in MM to induce cell death. Using a suite of small molecules that target various activities of eIF4F, we observed that cell survival and DEX resistance are attenuated upon eIF4F inhibition in MM cell lines and primary human samples. Levels of MYC and myeloid cell leukemia 1, two known eIF4F-responsive transcripts and key survival factors in MM, were reduced upon eIF4F inhibition, and their independent suppression also synergized with DEX. Inhibition of eIF4F in MM exerts pleotropic effects unraveling a unique therapeutic opportunity. PMID:25197055

Robert, Francis; Roman, William; Bramoullé, Alexandre; Fellmann, Christof; Roulston, Anne; Shustik, Chaim; Porco, John A.; Shore, Gordon C.; Sebag, Michael; Pelletier, Jerry

2014-01-01

286

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

287

A Preliminary Engineering Design of Intravascular Dual-Frequency Transducers for Contrast-Enhanced Acoustic Angiography and Molecular Imaging  

PubMed Central

Current intravascular ultrasound (IVUS) probes are not optimized for contrast detection because of their design for high-frequency fundamental-mode imaging. However, data from transcutaneous contrast imaging suggests the possibility of utilizing contrast ultrasound for molecular imaging or vasa vasorum assessment to further elucidate atherosclerotic plaque deposition. This paper presents the design, fabrication, and characterization of a small-aperture (0.6 × 3 mm) IVUS probe optimized for high-frequency contrast imaging. The design utilizes a dual-frequency (6.5 MHz/30 MHz) transducer arrangement for exciting microbubbles at low frequencies (near their resonance) and detecting their broadband harmonics at high frequencies, minimizing detected tissue backscatter. The prototype probe is able to generate nonlinear microbubble response with more than 1.2 MPa of rarefractional pressure (mechanical index: 0.48) at 6.5 MHz, and is also able to detect microbubble response with a broadband receiving element (center frequency: 30 MHz, ?6-dB fractional bandwidth: 58.6%). Nonlinear super-harmonics from microbubbles flowing through a 200-?m-diameter micro-tube were clearly detected with a signal-to-noise ratio higher than 12 dB. Preliminary phantom imaging at the fundamental frequency (30 MHz) and dual-frequency super-harmonic imaging results suggest the promise of small aperture, dual-frequency IVUS transducers for contrast-enhanced IVUS imaging. PMID:24801226

Ma, Jianguo; Martin, K. Heath; Dayton, Paul A.; Jiang, Xiaoning

2014-01-01

288

The L-4F mimetic peptide prevents insulin resistance through increased levels of HO-1, pAMPK,  

E-print Network

The L-4F mimetic peptide prevents insulin resistance through increased levels of HO-1, pAMPK, and p. G. Abraham. The L-4F mimetic peptide prevents insulin resistance through increased levels of HO-1, p hypoth- esized that L-4F reduces adiposity via increased pAMPK, pAKT, HO-1, and increased insulin

Abraham, Nader G.

289

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

290

External Flow of an Acoustically Levitated Droplet  

Microsoft Academic Search

One of the major recent advances for experiments in containerless processing is acoustic levitation. Although there are a\\u000a lot of previous studies for acoustic levitation, characteristic of external flow of an acoustically levitated droplet is not\\u000a experimentally examined enough. In this study, external flow field has been observed by using high speed camera and Particle\\u000a Image Velocimetry. In the case

Koji Hasegawa; Yutaka Abe; Akiko Fujiwara; Yuji Yamamoto; Kazuyoshi Aoki

2008-01-01

291

Acoustic Inversion in Optoacoustic Tomography: A Review  

PubMed Central

Optoacoustic tomography enables volumetric imaging with optical contrast in biological tissue at depths beyond the optical mean free path by the use of optical excitation and acoustic detection. The hybrid nature of optoacoustic tomography gives rise to two distinct inverse problems: The optical inverse problem, related to the propagation of the excitation light in tissue, and the acoustic inverse problem, which deals with the propagation and detection of the generated acoustic waves. Since the two inverse problems have different physical underpinnings and are governed by different types of equations, they are often treated independently as unrelated problems. From an imaging standpoint, the acoustic inverse problem relates to forming an image from the measured acoustic data, whereas the optical inverse problem relates to quantifying the formed image. This review focuses on the acoustic aspects of optoacoustic tomography, specifically acoustic reconstruction algorithms and imaging-system practicalities. As these two aspects are intimately linked, and no silver bullet exists in the path towards high-performance imaging, we adopt a holistic approach in our review and discuss the many links between the two aspects. Four classes of reconstruction algorithms are reviewed: time-domain (so called back-projection) formulae, frequency-domain formulae, time-reversal algorithms, and model-based algorithms. These algorithms are discussed in the context of the various acoustic detectors and detection surfaces which are commonly used in experimental studies. We further discuss the effects of non-ideal imaging scenarios on the quality of reconstruction and review methods that can mitigate these effects. Namely, we consider the cases of finite detector aperture, limited-view tomography, spatial under-sampling of the acoustic signals, and acoustic heterogeneities and losses. PMID:24772060

Rosenthal, Amir; Ntziachristos, Vasilis; Razansky, Daniel

2013-01-01

292

Virtual touch tissue imaging on acoustic radiation force impulse elastography: a new technique for differential diagnosis between benign and malignant thyroid nodules.  

PubMed

Objectives- Acoustic radiation force impulse elastography is a newly developed ultrasound elasticity imaging technique that included both Virtual Touch tissue quantification and Virtual Touch tissue imaging (VTI; Siemens Medical Solutions, Mountain View, CA). This study aimed to evaluate the usefulness of VTI in differentiating malignant from benign thyroid nodules. Methods- This study included 192 consecutive patients with thyroid nodules (n = 219) who underwent surgery for compressive symptoms or suspicion of malignancy. Tissue stiffness on VTI elastography was scored from 1 (soft) to 6 (hard). The VTI scores between malignant and benign thyroid nodules were compared. The intraobserver and interobserver agreement for VTI elastography was also assessed. Results- On VTI elastography: score 1 was found in 84 nodules (all benign); score 2 in 37 nodules (3 papillary carcinomas and 34 benign nodules); score 3 in 25 nodules (1 medullary carcinoma, 6 papillary carcinomas, and 18 benign nodules); score 4 in 53 nodules (50 papillary carcinomas and 3 benign nodules); score 5 in 17 nodules (14 papillary carcinomas and 3 benign nodules); and score 6 in 3 nodules (all papillary carcinomas). A VTI elasticity score of 4 or greater was highly predictive of malignancy (P< .01), and the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 87.0% (67 of 77), 95.8% (136 of 142), 91.8% (67 of 73), 93.1% (136 of 146), and 92.7% (203 of 219), respectively. The ? values were 0.69 for intraobserver agreement and 0.85 for interobserver agreement. Conclusions- Virtual Touch tissue elasticity imaging has great potential as an adjunctive tool combined with conventional sonography for differential diagnosis between benign and malignant thyroid nodules. PMID:24658938

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

2014-04-01

293

Preparation and electrochemical studies of Y-doped LiVPO 4 F cathode materials for lithium-ion batteries  

Microsoft Academic Search

Y-doped LiVPO4F cathode materials were prepared by a carbothermal reduction(CTR) process. The properties of the Y-doped LiVPO4F samples were investigated by X-ray diffraction (XRD) and electrochemical measurements. XRD studies show that the Y-doped\\u000a LiVPO4F samples have the same triclinic structure as the undoped LiVPO4F. The Li extraction\\/insertion performances of Y-doped LiVPO4F samples were investigated through charge\\/discharge, cyclic voltammogram (CV), and

Shengkui Zhong; Fengpeng Li; Jiequn Liu; Yanhong Li; Xingsheng Deng

2009-01-01

294

Extraction of overt verbal response from the acoustic noise in a functional magnetic resonance imaging scan by use of segmented active noise cancellation.  

PubMed

A method to extract the subject's overt verbal response from the obscuring acoustic noise in an fMRI scan is developed by applying active noise cancellation with a conventional MRI microphone. Since the EPI scanning and its accompanying acoustic noise in fMRI are repetitive, the acoustic noise in one time segment was used as a reference noise in suppressing the acoustic noise in subsequent segments. However, the acoustic noise from the scanner was affected by the subject's movements, so the reference noise was adaptively adjusted as the scanner's acoustic properties varied in time. This method was successfully applied to a cognitive fMRI experiment with overt verbal responses. PMID:15723385

Jung, Kwan-Jin; Prasad, Parikshit; Qin, Yulin; Anderson, John R

2005-03-01

295

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

296

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

297

Analysis of the inhibitory mechanism of D-allose on MOLT-4F leukemia cell proliferation.  

PubMed

D-Allose, the C-3 epimer of D-glucose, is one of the rare sugars found in nature. In the present study, we have elucidated for the first time that various leukemia cell lines have different susceptibility to anti-proliferative activity of D-allose, and that this difference is related to the difference in induction of thioredoxin interacting protein (TXNIP) expression. We examined 5 leukemia cell lines (MOLT-4F, IM-9, HL-60, BALL-1 and Daudi), and found that MOLT-4F (T-cell lymphoblastic leukemia) had the highest susceptibility to D-allose, and that Daudi (Burkitt's lymphoma) had the lowest. D-Allose significantly slowed the cell cycle progression without causing apoptosis of MOLT-4F cells. Intracellular TXNIP expression was specifically and markedly enhanced in MOLT-4F cells by D-allose treatment, and subsequent increase of p27(kip1), a cell cycle inhibitor, was observed. On the other hand, D-allose did not increase TXNIP and p27(kip1) levels at all in Daudi cells. These results indicate that D-allose suppresses MOLT-4F cell proliferation possibly by the inhibition of cell cycle progression via induction of TXNIP expression. PMID:19393559

Hirata, Yuko; Saito, Madoka; Tsukamoto, Ikuko; Yamaguchi, Fuminori; Sui, Li; Kamitori, Kazuyo; Dong, Youyi; Uehara, Eisuke; Konishi, Ryoji; Janjua, Najma; Tokuda, Masaaki

2009-05-01

298

Plasma Diagnostic Potential of 2p4f in N+—Accurate Wavelengths and Oscillator Strengths  

NASA Astrophysics Data System (ADS)

Radiative emission lines from nitrogen and its ions are often observed in nebula spectra, where the N2 + abundance can be inferred from lines of the 2p4f configuration. In addition, intensity ratios between lines of the 2p3p-2p3s and 2p4f-2p3d transition arrays can serve as temperature diagnostics. To aid abundance determinations and plasma diagnostics, wavelengths and oscillator strengths were calculated with high precision for electric dipole (E1) transitions from levels in the 2p4f configuration of N+. Electron correlation and relativistic effects, including the Breit interaction, were systematically taken into account within the framework of the multiconfiguration Dirac-Hartree-Fock method. Except for the 2p4f-2p4d transitions with quite large wavelengths and the two-electron-one-photon 2p4f-2s2p 3 transitions, the uncertainties of the present calculations were controlled to within 3% and 5% for wavelengths and oscillator strengths, respectively. We also compared our results with other theoretical and experimental values when available. Discrepancies were found between our calculations and previous calculations due to the neglect of relativistic effects in the latter.

Shen, Xiaozhi; Li, Jiguang; Jönsson, Per; Wang, Jianguo

2015-03-01

299

Performance limitations in underwater acoustic telemetry  

Microsoft Academic Search

Performance limitations in digital acoustic telemetry are addressed. Increases in computational capabilities have led to a number of complex but practical solutions aimed at increasing the reliability of acoustic data links. These solutions range from ocean-basin scale data telemetry to video-image transmission at a few hundred yards' distance. The opportunity to implement highly complex tasks in real time on modest

J. A. Catipovic

1990-01-01

300

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

301

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

302

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

303

Does the 4f-shell contribute to bonding in tetravalent lanthanide halides?  

NASA Astrophysics Data System (ADS)

Lanthanide tetrahalide molecules LnX4 (Ln = Ce, Pr, Tb; X = F, Cl, Br, I) have been investigated by density functional theory at the levels of the relativistic Zero Order Regular Approximation and the relativistic energy-consistent pseudopotentials, using frozen small- and medium-cores. The calculated bond lengths and vibrational frequencies are close to the experimental data. Our calculations indicate 4f shell contributions to bonding in LnX4, in particular for the early lanthanides, which show significant overlap between the Ln 4f-shell and the halogen np-shells. The 4f shells contribute to Ln-X bonding in LnX4 about one third more than in LnX3.

Ji, Wen-Xin; Xu, Wei; Xiao, Yi; Wang, Shu-Guang

2014-12-01

304

Piezoelectrically driven vertical cavity acoustic transducers for the convective transport and rapid detection of DNA and protein binding to DNA microarrays with SPR imaging--a parametric study.  

PubMed

Mixing within the microdomain is limited because convective mixing cannot be achieved since diffusion dominates as the main form of transport. Hence microassays can take on the order of 1 to 72 h, without the aid of a passive or active mixer to shorten the time of transport of a target molecule to a probe (Lai et al., 2004). Liu et al. (2002, 2003) developed a low cost cavitation microstreaming based mixer which is easy to implement and use, but no comprehensive study has been done to optimize such a mixer for various applications. We present a study of the effects of various frequencies and cavity parameters on mixing using dye and surface based assays with protein, DNA, and nanoparticles to obtain an optimum mixing frequency and configuration for a wide range of assay applications. We present a novel method to monitor real time binding using surface plasmon resonance imaging (SPRI) coupled with a vertical cavity acoustic transducer (VCAT) micromixer for various biomolecule surface assays. The combination of VCAT and SPRI allows assay signal saturation within one minute while conserving reagent volume. The kinetic rate constant for adsorption (k(a)) and desorption (k(d)) as well as the limit of detection (LOD) of 5 nM for the DNA duplex formation are reported using this VCAT micromixer. PMID:22503031

Okabe, Yuka; Chen, Yulin; Purohit, Rishi; Corn, Robert M; Lee, Abraham P

2012-05-15

305

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

306

Modification of Kirchhoff migration with variable sound speed and attenuation for acoustic imaging of media and application to tomographic imaging of the breast  

PubMed Central

Purpose: To explore the feasibility of improving cross-sectional reflection imaging of the breast using refractive and attenuation corrections derived from ultrasound tomography data. Methods: The authors have adapted the planar Kirchhoff migration method, commonly used in geophysics to reconstruct reflection images, for use in ultrasound tomography imaging of the breast. Furthermore, the authors extended this method to allow for refractive and attenuative corrections. Using clinical data obtained with a breast imaging prototype, the authors applied this method to generate cross-sectional reflection images of the breast that were corrected using known distributions of sound speed and attenuation obtained from the same data. Results: A comparison of images reconstructed with and without the corrections showed varying degrees of improvement. The sound speed correction resulted in sharpening of detail, while the attenuation correction reduced the central darkening caused by path length dependent losses. The improvements appeared to be greatest when dense tissue was involved and the least for fatty tissue. These results are consistent with the expectation that denser tissues lead to both greater refractive effects and greater attenuation. Conclusions: Although conventional ultrasound techniques use time-gain control to correct for attenuation gradients, these corrections lead to artifacts because the true attenuation distribution is not known. The use of constant sound speed leads to additional artifacts that arise from not knowing the sound speed distribution. The authors show that in the context of ultrasound tomography, it is possible to construct reflection images of the breast that correct for inhomogeneous distributions of both sound speed and attenuation. PMID:21452737

Schmidt, Steven; Duric, Nebojsa; Li, Cuiping; Roy, Olivier; Huang, Zhi-Feng

2011-01-01

307

?-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

308

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

309

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

310

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

311

Imaging feedback for histotripsy by characterizing dynamics of acoustic radiation force impulse (ARFI)-induced shear waves excited in a treated volume.  

PubMed

Our previous study indicated that shear waves decay and propagate at a lower speed as they propagate into a tissue volume mechanically fractionated by histotripsy. In this paper, we hypothesize that the change in the shear dynamics is related to the degree of tissue fractionation, and can be used to predict histotripsy treatment outcomes. To test this hypothesis, lesions with different degrees of tissue fractionation were created in agar-graphite tissue phantoms and ex vivo kidneys with increasing numbers of therapy pulses, from 0 to 2000 pulses per treatment location. The therapy pulses were 3-cycle 750-kHz focused ultrasound delivered at a peak negative/positive pressure of 17/108 MPa and a repetition rate of 50 Hz. The shear waves were excited by acoustic radiation force impulse (ARFI) focused at the center of the lesion. The spatial and temporal behavior of the propagating shear waves was measured with ultrasound plane wave imaging. The temporal displacement profile at a lateral location 10 mm offset to the shear excitation region was detected with M-mode imaging. The decay and delay of the shear waves were quantitatively characterized on the temporal displacement profile. Results showed significant changes in two characteristics on the temporal displacement profile: the peak-to-peak displacement decayed exponentially with increasing numbers of therapy pulses; the relative time-to-peak displacement increased with increasing numbers of therapy pulses, and appeared to saturate at higher numbers of pulses. Correspondingly, the degree of tissues fractionation, as indicated by the percentage of structurally intact cell nuclei, decreased exponentially with increasing numbers of therapy pulses. Strong linear correlations were found between the two characteristics and the degree of tissue fractionation. These results suggest that the characteristics of the shear temporal displacement profile may provide useful feedback information regarding the treatment outcomes. PMID:24960703

Wang, Tzu-Yin; Hall, Timothy L; Xu, Zhen; Fowlkes, J Brian; Cain, Charles A

2014-07-01

312

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

313

Apolipoprotein A-I mimetic 4F alters the function of human monocyte-derived macrophages  

PubMed Central

HDL and its major protein component apolipoprotein A-I (apoA-I) exert anti-inflammatory effects, inhibit monocyte chemotaxis/adhesion, and reduce vascular macrophage content in inflammatory conditions. In this study, we tested the hypothesis that the apoA-I mimetic 4F modulates the function of monocyte-derived macrophages (MDMs) by regulating the expression of key cell surface receptors on MDMs. Primary human monocytes and THP-1 cells were treated with 4F, apoA-I, or vehicle for 7 days and analyzed for expression of cell surface markers, adhesion to human endothelial cells, phagocytic function, cholesterol efflux capacity, and lipid raft organization. 4F and apoA-I treatment decreased the expression of HLA-DR, CD86, CD11b, CD11c, CD14, and Toll-like receptor-4 (TLR-4) compared with control cells, suggesting the induction of monocyte differentiation. Both treatments abolished LPS-induced mRNA for monocyte chemotactic protein-1 (MCP-1), macrophage inflammatory protein-1 (MIP-1), regulated on activation, normal T-expressed and presumably secreted (RANTES), IL-6, and TNF-? but significantly upregulated LPS-induced IL-10 expression. Moreover, 4F and apoA-I induced a 90% reduction in the expression of CD49d, a ligand for the VCAM-1 receptor, with a concurrent decrease in monocyte adhesion (55% reduction) to human endothelial cells and transendothelial migration (34 and 27% for 4F and apoA-I treatments) compared with vehicle treatment. In addition, phagocytosis of dextran-FITC beads was inhibited by 4F and apoA-I, a response associated with reduced expression of CD32. Finally, 4F and apoA-I stimulated cholesterol efflux from MDMs, leading to cholesterol depletion and disruption of lipid rafts. These data provide evidence that 4F, similar to apoA-I, induces profound functional changes in MDMs, possibly due to differentiation to an anti-inflammatory phenotype. PMID:20219948

Smythies, Lesley E.; White, C. Roger; Maheshwari, Akhil; Palgunachari, M. N.; Anantharamaiah, G. M.; Chaddha, Manjula; Kurundkar, Ashish R.

2010-01-01

314

Regulation of Pou4f3 Gene Expression in Hair Cells by 5’ DNA in Mice  

PubMed Central

The POU-domain transcription POU4F3 is expressed in the sensory cells of the inner ear. Expression begins shortly after commitment to the hair cell (HC) fate, and continues throughout life. It is required for terminal HC differentiation and survival. To explore regulation of the murine Pou4f3 gene, we linked enhanced green fluorescent protein (eGFP) to 8.5 kb of genomic sequence 5’ to the start codon in transgenic mice. eGFP was uniformly present in all embryonic and neonatal HCs. Expression of eGFP was also observed in developing Merkel cells and olfactory neurons as well as adult inner and vestibular HCs, mimicking the normal expression pattern of POU4F3 protein, with the exception of adult outer HCs. Apparently ectopic expression was observed in developing inner ear neurons. On a Pou4f3 null background, the transgene produced expression in embryonic HCs which faded soon after birth both in vivo and in vitro. Pou4f3 null HCs treated with caspase 3 and 9 inhibitors survived longer than untreated HCs, but still showed reduced expression of eGFP. The results suggest the existence of separate enhancers for different HC types, as well as strong autoregulation of the Pou4f3 gene. Bioinformatic analysis of four divergent mammalian species revealed three highly-conserved regions within the transgene: 400 bp immediately 5’ to the Pou4f3 ATG, a short sequence at -1.3 kb, and a longer region at -8.2 to -8.5 kb. The latter contained E-box motifs that bind bHLH transcription factors, including motifs activated by ATOH1. Co-transfection of HEK293 or VOT-E36 cells with ATOH1 and the transgene as a reporter enhanced eGFP expression when compared to the transgene alone. Chromatin immunoprecipitation of the three highly conserved regions revealed binding of ATOH1 to the distal-most conserved region. The results are consistent with regulation of Pou4f3 in HCs by ATOH1 at a distal enhancer. PMID:21958861

Masuda, Masatsugu; Dulon, Didier; Pak, Kwang; Mullen, Lina M.; Li, Yan; Erkman, Linda; Ryan, Allen F.

2011-01-01

315

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

316

Three-dimensional imaging of the petrous bone for the middle fossa approach to the internal acoustic meatus: an experimental study  

Microsoft Academic Search

The goal of this study was to highlight the feasibility of creating three-dimensional (3D) pictures of the petrous bone from a routine CT examination which can be used for a middle fossa approach to the internal acoustic meatus, in order to secure this operation. The surgical aim is to reach the roof of the internal acoustic meatus directly without injuring

C. Page; F. Taha; Le D. Gars

2002-01-01

317

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

318

Acoustic transducer for acoustic microscopy  

DOEpatents

A shear acoustic transducer-lens system is described 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. 9 figs.

Khuri-Yakub, B.T.; Chou, C.H.

1990-03-20

319

Acoustic imaging of the passage of turbidity currents and associated hydraulic jumps on underlying cyclic step bedforms. Squamish, BC  

NASA Astrophysics Data System (ADS)

Active channelized turbidity currents have been repeatedly imaged in 60m of water on the Squamish prodelta. Previously in 2011 and 2012, the prodelta has been repetitively surveyed on daily and hourly timescales and is thus known to exhibit trains of bedforms along the channel floors that resemble cyclic steps that migrate upslope intermittently. Beyond the channel mouths, clear turbidity current flows had previously been detected using a seabed mounted ADCP. In order to directly observe the passage of the flow in the channelized section of the prodelta, in June 2013 a vessel was moored using 4 anchors directly above one of the channels. The vessel operated two hull-mounted single beam sonars at 28 and 200 kHz and a multibeam sonar at 95 kHz, all imaging a near stationary point or swath within or across the channel. In addition a 1200 kHz ADCP was suspended 12m above the seabed and two 500 kHz imaging multibeams were suspended 10m above the channel floor. One of the suspended multibeams was oriented facing upslope examining a 150m range, 120 degree, plan view sector of the channel. The second suspended multibeam was oriented downward to derive a ~30m long along-track section over the length of one of the bedforms. A mechanically dipped CTD and optical backscatter probe was lower repeatedly directly into the active flows until it touched the seabed at about one minute periods. Over a period of 5 days, between 1 and 7 discrete flows per day were monitored passing by within one hour of low water. Their head velocities ranged from ~ 0.5 to 2.5m/s and their thicknesses were generally in the 3-5m range. Looking upstream in plan view, the lobate head of the approaching flows could be seen to be constricted to specific talwegs within the channel floor and rise up and over successive cyclic step bedforms. The higher velocity flows exhibit clear turbulent eddies on their upper surface. The duration of the high velocity component of the flow rarely lasted for more than a few minutes. For the two highest velocity flows observed, a clear hydraulic jump could be seen in the suspended multibeam imagery just downstream of the base of the stoss face of the imaged bedform. The hull mounted sonars clearly reveal massive release of gas from the seabed in the wake of the head passage. Bathymetric surface differences from surveys from the preceding and following high tide period indicated multiple active feeder channels descending from the lip of the delta.

Hughes Clarke, J. E.

2013-12-01

320

Acoustic superlens using membrane-based metamaterials  

NASA Astrophysics Data System (ADS)

We report construction of an acoustic superlensing using two dimensional membrane-based negative-density metamaterials. When two point sources separated by a distance of 1/17 of the wavelength are placed near to a surface of the metamaterial slab, well-resolved images are formed on the opposite surface across the slab. The mechanism for the subwavelength resolution is the surface wave stemming from negative density. Potential applications include acoustic imaging and sensing.

Park, Jong Jin; Park, Choon Mahn; Lee, K. J. B.; Lee, Sam H.

2015-02-01

321

Measurements of ionization and attachment coefficients in 0.468% and 4.910% cC4F8\\/Ar mixtures and pure cC4F8  

Microsoft Academic Search

We measured the density normalized ionization coefficients and attachment coefficients in diluted c-C4F8\\/Ar mixtures and in pure perfluorocyclobutane (c-C4F8) by the steady-state Townsend method. The ionization coefficients in the mixture gas are almost equal to those in pure argon at the high E\\/N range but differ considerably at the low E\\/N range. The present coefficients in pure c-C4F8 agree well

Masahiro Yamaji; Yoshiharu Nakamura; Yukihiko Morokuma

2004-01-01

322

Low-frequency acoustic microscope  

Microsoft Academic Search

Low-frequency acoustic microscopy has demonstrated a tremendous potential for the nondestructive evaluation of metals, composite materials, and structural ceramics. This proposal allowed us to build a new, improved instrument with which can make not only amplitude, but also phase, measurements. The addition of the phase measurement capability allows us to do two dimensional image processing to extract more information from

B. T. Khuri-Yakub; Butrus T

1986-01-01

323

cells in the presence of insulin, transferrin and fibroflast growth factor (4F medium). This  

E-print Network

cells in the presence of insulin, transferrin and fibroflast growth factor (4F medium). This growth precursor cells might be under the control of proteolytic events for their expansion through cell multiplication. In addition to growth hormone (GH) and triiodothyronine (Tg), fetuin, a bovine fetal protein

Paris-Sud XI, Université de

324

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

E-print Network

and the associated insu- lin resistance and changes in serum levels of adiponectin, suggesting that increases in ROS.001). L-4F treatment increased serum adiponectin levels (P , 0.037) and de- creased adipogenesis in mouse oxidation, liver insulin action, and glucose uptake and positively affect serum triglyceride levels (12

Abraham, Nader G.

325

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

E-print Network

-C4F8) are synthesized, assessed, and dis- cussed. These include cross sections for total electron Sections. . . . . . . . . . . . . 451 3.1. Total electron scattering cross section, sc. . . . . . . . . . . . . . . . . . . . . . . . . 461 6.1. Electron beam determined total electron attachment cross section a

Magee, Joseph W.

326

FTIR spectroscopy of bacteriorhodopsin microcrystals at Beamline 1.4 F. Betancourt1  

E-print Network

FTIR spectroscopy of bacteriorhodopsin microcrystals at Beamline 1.4 F. Betancourt1 , S. Rouhani2 Fourier Transform IR (FTIR) spectroscopy to confirm the identity of the photointermediate6 . This year we photointermediates of the bacteriorhodopsin mutant F219L by means of FTIR spectroscopy. At 213K an early phase

327

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

328

48 CFR 47.303-4 - F.o.b. origin, freight prepaid.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false F.o.b. origin, freight prepaid. 47...Transportation in Supply Contracts 47.303-4 F.o.b. origin, freight prepaid. (a) Explanation of delivery term. F.o.b. origin, freight prepaid...

2010-10-01

329

Magnetic circular dichroism in Tb 3d~4f resonant photoemission G. van der Laan  

E-print Network

momenta we obtain fundamental spectra which require only the reduced matrix elements. The full multiplet is offering tremendous opportu- nities in the study of the electronic and magnetic structure of transitionMagnetic circular dichroism in Tb 3d~4f resonant photoemission G. van der Laan Daresbury Laboratory

330

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

331

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

332

Comparison of CF4 and C4F8 gas etching profiles by multiscale simulation  

NASA Astrophysics Data System (ADS)

The CF4 and C4F8 gas etching profiles of oxide films were compared by multiscale simulation that comprises gas reaction, sheath, and surface reaction models. The densities of CF3, CF2, and CF radicals in CF4/Ar or C4F8/Ar gas were measured and compared with those obtained by simulation using the gas reaction model. From this comparison, the electron temperatures were determined to be 2.8 and 4.5 eV for CF4 and C4F8 gases, respectively. In the sheath model, the behavior of ions in a sheath was simulated for sheath lengths calculated from these electron temperatures. In the surface reaction model, we simulated the formation of a polymer and active layers by CF2 radicals, determined the depth of etching resulting from ion bombardment, and obtained the etching profiles of the oxide films. The profile of a contact hole with a depth of 820 nm and an aperture diameter of 160 nm was simulated. The results showed that the photoresist height was approximately 70 nm greater and the bowing diameter was approximately 10 nm smaller in the case of using C4F8 gas than in the case of using CF4 gas. This is because the CF2 density in the C4F8 gas is approximately 30 times higher than that in the CF4 gas and the polymer layer more strongly protects the underlying film. When the etching profiles were simulated with a fixed density of positive ions but with various CF2 density, the bottom diameter was constant but the bowing diameter changed for CF2 densities between 1013 and 1014 cm?3.

Takagi, Shigeyuki; Onoue, Seiji; Nishitani, Kazuhito; Shinnmura, Tadashi; Shigesato, Yuzo

2015-03-01

333

The Modal Logic S4F, the Default Logic, and the Logic HereandThere Mirosl/aw Truszczy  

E-print Network

The Modal Logic S4F, the Default Logic, and the Logic Here­and­There Mirosl/aw Truszczy â?? nski logic S4F provides an account for the default logic of Reiter, and several modal nonmonotonic logics of knowl­ edge and belief. In this paper we focus on a fragment of the logic S4F concerned with modal

Truszczynski, Miroslaw

334

Oscillating acoustic streaming jet  

NASA Astrophysics Data System (ADS)

The present paper provides the first experimental investigation of an oscillating acoustic streaming jet. The observations are performed in the far field of a 2 MHz circular plane ultrasound transducer introduced in a rectangular cavity filled with water. Measurements are made by Particle Image Velocimetry (PIV) in horizontal and vertical planes near the end of the cavity. Oscillations of the jet appear in this zone, for a sufficiently high Reynolds number, as an intermittent phenomenon on an otherwise straight jet fluctuating in intensity. The observed perturbation pattern is similar to that of former theoretical studies. This intermittently oscillatory behavior is the first step to the transition to turbulence.

Moudjed, Brahim; Botton, Valéry; Henry, Daniel; Millet, Séverine; Garandet, Jean-Paul; Ben-Hadid, Hamda

2014-11-01

335

Ion effects on CF2 surface interactions during C3F8 and C4F8 plasma processing of Si  

NASA Astrophysics Data System (ADS)

Surface interactions of difluorocarbene (CF2) molecules were investigated using our LIF based imaging of radicals interacting with surfaces (IRIS) apparatus. LIF data of CF2 in C3F8 and C4F8 plasma molecular beams reveal that the relative densities of CF2 increase with increasing rf power and source pressure in both plasma systems. The surface reactivity of CF2 molecules during C3F8 and C4F8 plasma processing of room temperature Si substrates was also measured over a broad rf power range and at different pressures. A scatter coefficient (S) greater than one was measured for all unperturbed systems, indicating that CF2 molecules are produced at the substrate surface during film deposition. The same systems were also studied under ion-limited conditions, yielding S~1, clear indication that ions are partially responsible for CF2 surface production. Plasma ions were identified using plasma-ion mass spectrometry. These data indicate that higher levels of CxFy+ (x>1) are produced in the C4F8 plasmas. X-ray photoelectron spectroscopy analyses of treated substrates showed that amorphous fluorocarbon films were deposited during plasma processing of the substrates. A positive correlation was found between S(CF2) and film composition of FC materials deposited in both the IRIS apparatus and independent reactors.

Martin, Ina T.; Fisher, Ellen R.

2004-09-01

336

Air-coupled acoustic thermography for in-situ evaluation  

NASA Technical Reports Server (NTRS)

Acoustic thermography uses a housing configured for thermal, acoustic and infrared radiation shielding. For in-situ applications, the housing has an open side adapted to be sealingly coupled to a surface region of a structure such that an enclosed chamber filled with air is defined. One or more acoustic sources are positioned to direct acoustic waves through the air in the enclosed chamber and towards the surface region. To activate and control each acoustic source, a pulsed signal is applied thereto. An infrared imager focused on the surface region detects a thermal image of the surface region. A data capture device records the thermal image in synchronicity with each pulse of the pulsed signal such that a time series of thermal images is generated. For enhanced sensitivity and/or repeatability, sound and/or vibrations at the surface region can be used in feedback control of the pulsed signal applied to the acoustic sources.

Zalameda, Joseph N. (Inventor); Winfree, William P. (Inventor); Yost, William T. (Inventor)

2010-01-01

337

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

338

Isolating the auditory system from acoustic noise during functional magnetic resonance imaging: Examination of noise conduction through the ear canal, head, and bodya)  

PubMed Central

Approaches were examined for reducing acoustic noise levels heard by subjects during functional magnetic resonance imaging (fMRI), a technique for localizing brain activation in humans. Specifically, it was examined whether a device for isolating the head and ear canal from sound (a “helmet”) could add to the isolation provided by conventional hearing protection devices (i.e., earmuffs and earplugs). Both subjective attenuation (the difference in hearing threshold with versus without isolation devices in place) and objective attenuation (difference in ear-canal sound pressure) were measured. In the frequency range of the most intense fMRI noise (1–1.4 kHz), a helmet, earmuffs, and earplugs used together attenuated perceived sound by 55–63 dB, whereas the attenuation provided by the conventional devices alone was substantially less: 30–37 dB for earmuffs, 25–28 dB for earplugs, and 39–41 dB for earmuffs and earplugs used together. The data enabled the clarification of the relative importance of ear canal, head, and body conduction routes to the cochlea under different conditions: At low frequencies (?500 Hz), the ear canal was the dominant route of sound conduction to the cochlea for all of the device combinations considered. At higher frequencies (>500 Hz), the ear canal was the dominant route when either earmuffs or earplugs were worn. However, the dominant route of sound conduction was through the head when both earmuffs and earplugs were worn, through both ear canal and body when a helmet and earmuffs were worn, and through the body when a helmet, earmuffs, and earplugs were worn. It is estimated that a helmet, earmuffs, and earplugs together will reduce the most intense fMRI noise levels experienced by a subject to 60–65 dB SPL. Even greater reductions in noise should be achievable by isolating the body from the surrounding noise field. PMID:11206150

Ravicz, Michael E.; Melcher, Jennifer R.

2007-01-01

339

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

340

LOCAPHONY - NEW ACOUSTICAL METHOD OF EXPRESS FUNCTIONAL MEDICINE DIAGNOSTICS  

Microsoft Academic Search

Locaphony is a new developed method of quick functional medicine diagnostics, based on objective acoustical percussion of human internal organs. Locaphony permits to determine the acoustical projections of organs on the skin, estimate the safety of tissue and detect the inflammation processes. The 2D- images are the result of such diagnostics and these images contain new information in comparison with

V. Svet; J. Blinkov; S. Nikolaev; V. Murashev

341

A finite-element method model of soft tissue response to impulsive acoustic radiation force  

Microsoft Academic Search

Several groups are studying acoustic radiation force and its ability to image the mechanical properties of tissue. Acoustic radiation force impulse (ARFI) imaging is one modality using standard diagnostic ultrasound scanners to generate localized, impulsive, acoustic radiation forces in tissue. The dynamic response of tissue is measured via conventional ultrasonic speckle-tracking methods and provides information about the mechanical properties of

Mark L. Palmeri; Amy C. Sharma; Richard R. Bouchard; Roger W. Nightingale; Kathryn R Nightingale

2005-01-01

342

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

343

Mechanism of film formation on nickel anodes in a molten NH 4F·2HF  

Microsoft Academic Search

The mechanism of film formation on the Ni anode in a well dehydrated melt of NH4F·2HF was studied at 100°C. The potentiodynamic and potentiostatic polarization behaviors of the Ni anode were investigated to elucidate the anodic processes. The oxidized layer was composed of NiF2 with a small amount of nickel oxides such as NiO and Ni2O3 or oxyfluorides having plural

A. Tasaka; Y. Tsukuda; S. Yamada; K. Matsushita; A. Kohmura; N. Muramatsu; H. Takebayashi; T. Mimaki

1999-01-01

344

Extended analysis of the 5g. -->. 4f emissions in H/sub 2/  

SciTech Connect

An analysis starting from Hund's case d has been used to extend the work of Herzberg and Jungen on the 5g..-->..4f emissions in H/sub 2/. A simple analytical expression for the line intensities is presented that agrees with their calculations is about 1%. All of the experimentally observed lines have been accounted for by including higher vibrational levels in our calculations.

Chang, E.S.; Pulchtopek, S.; Eyler, E.E.

1984-01-15

345

Fine structure of the H2 5g4f inter-Rydberg transition revealed by difference frequency laser spectroscopy  

E-print Network

Fine structure of the H2 5g­4f inter-Rydberg transition revealed by difference frequency laser of the 5g­4f inter-Rydberg band of H2 has been recorded with a difference frequency laser system composed of absorption lines, some transitions from high vibrational levels of the 5g triplet manifold to 4

Oka, Takeshi

346

Superhydrophobic treatment using atmospheric-pressure He/C4F8 plasma for buoyancy improvement  

NASA Astrophysics Data System (ADS)

A superhydrophobic miniature boat was fabricated with aluminum alloy plates treated with atmospheric-pressure helium (He)/octafluorocyclobutane (C4F8) plasma using 13.56 MHz rf power. When only 0.13% C4F8 was added to He gas, the contact angle of the surface increased to 140° and the surface showed superhydrophobic properties. On the basis of chemical and morphological analyses, fluorinated functional groups (CF, CF2, and CF3) and nano-/micro-sized particles were detected on the Al surface. These features brought about superhydrophobicity similar to the lotus effect. While the miniature boat, assembled with plasma-treated plates, was immersed in water, a layer of air (i.e., a plastron) surrounded the superhydrophobic surfaces. This effect contributed to the development of a 4.7% increase in buoyancy. In addition, the superhydrophobic properties lasted for two months under the submerged condition. These results demonstrate that treatment with atmospheric-pressure He/C4F8 plasma is a promising method of improving the load capacity and antifouling properties, and reducing the friction of marine ships through a fast and low-cost superhydrophobic treatment process.

Noh, Sooryun; Moon, A.-Young; Moon, Se Youn

2015-04-01

347

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

348

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

349

Study of surface plasmons with a scanning acoustic microscope  

SciTech Connect

A new technique for investigating the surface plasmons by means of a scanning acoustic microscope is proposed. Within this technique, the surface electromagnetic wave (plasmon polariton) is excited by laser radiation on one side of a metal film, while a scanning acoustic microscope excites surface acoustic waves on the other side of the film. Obtained for the first time, the acoustic images of plasmons, propagating on the grating surface, demonstrate the possibility of studying the plasmon wave field distribution by means of a scanning acoustic microscope. (nonlinear optical phenomena)

Bereiter-Hahn, J; Blase, C [Kinematishe Zellforshung, Johann Wolfgang Goethe University, Germany, Frankfurt am Main (Germany); Lozovik, Yurii E [Institute of Spectroscopy, Russian Academy of Sciences, Troitsk, Moscow region (Russian Federation); Nazarov, Maksim M; Shkurinov, A P [Department of Physics, M.V. Lomonosov Moscow State University, Moscow (Russian Federation)

2003-05-31

350

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

351

Acoustic cryocooler  

DOEpatents

An acoustic cryocooler with no moving parts is formed from a thermoacoustic driver (TAD) driving a pulse tube refrigerator (PTR) through a standing wave tube. Thermoacoustic elements in the TAD are spaced apart a distance effective to accommodate the increased thermal penetration length arising from the relatively low TAD operating frequency in the range of 15-60 Hz. At these low operating frequencies, a long tube is required to support the standing wave. The tube may be coiled to reduce the overall length of the cryocooler. One or two PTR's are located on the standing wave tube adjacent antinodes in the standing wave to be driven by the standing wave pressure oscillations. It is predicted that a heat input of 1000 W at 1000 K will maintian a cooling load of 5 W at 80 K.

Swift, Gregory W. (Santa Fe, NM); Martin, Richard A. (Los Alamos, NM); Radenbaugh, Ray (Louisville, CO)

1990-01-01

352

Acoustic optic hybrid (AOH) sensor  

PubMed

The ability of laser vibrometers to receive and process acoustic echoes from the water surface above a submerged target is established and evaluated. Sonar echoes from a submerged target are collected from the water surface by a laser vibrometer. Feasibility of this approach to sensing underwater sound is demonstrated. If the acoustic excitation at an otherwise undisturbed water surface is 195 to 168 dB re: 1 microPa, signal-to-noise ratio (SNR), at the vibrometer output, is shown to range from about 46 to 6 dB. Capillary waves and gravity waves at the water surface are expected and shown to have some destructive effect on the process of echo retrieval. A series of experiments to quantify the surface wave effects is described. The wave experiment results are reported. A successful attempt to acquire echoes from a submerged target over a grid of points for further processing into a three-dimensional image is made and described. The data acquisition and beamforming techniques constitute a three-dimensional, acoustic optic, synthetic aperture sonar (SAS). Beamformed images are included. For an aircraft towing acoustic sensors through the water with a mechanical link, this technique holds the promise of increased safety and improved fuel efficiency. PMID:11008811

Matthews; Arrieta

2000-09-01

353

Near-field acoustic streaming jet  

NASA Astrophysics Data System (ADS)

A numerical and experimental investigation of the acoustic streaming flow in the near field of a circular plane ultrasonic transducer in water is performed. The experimental domain is a parallelepipedic cavity delimited by absorbing walls to avoid acoustic reflection, with a top free surface. The flow velocities are measured by particle image velocimetry, leading to well-resolved velocity profiles. The theoretical model is based on a linear acoustic propagation model, which correctly reproduces the acoustic field mapped experimentally using a hydrophone, and an acoustic force term introduced in the Navier-Stokes equations under the plane-wave assumption. Despite the complexity of the acoustic field in the near field, in particular in the vicinity of the acoustic source, a good agreement between the experimental measurements and the numerical results for the velocity field is obtained, validating our numerical approach and justifying the planar wave assumption in conditions where it is a priori far from obvious. The flow structure is found to be correlated with the acoustic field shape. Indeed, the longitudinal profiles of the velocity present a wavering linked to the variations in acoustic intensity along the beam axis and transverse profiles exhibit a complex shape strongly influenced by the transverse variations of the acoustic intensity in the beam. Finally, the velocity in the jet is found to increase as the square root of the acoustic force times the distance from the origin of the jet over a major part of the cavity, after a strong short initial increase, where the velocity scales with the square of the distance from the upstream wall.

Moudjed, B.; Botton, V.; Henry, D.; Millet, S.; Garandet, J. P.; Ben Hadid, H.

2015-03-01

354

Advanced fiber-optic acoustic sensors  

NASA Astrophysics Data System (ADS)

Acoustic sensing is nowadays a very demanding field which plays an important role in modern society, with applications spanning from structural health monitoring to medical imaging. Fiber-optics can bring many advantages to this field, and fiber-optic acoustic sensors show already performance levels capable of competing with the standard sensors based on piezoelectric transducers. This review presents the recent advances in the field of fiber-optic dynamic strain sensing, particularly for acoustic detection. Three dominant technologies are identified — fiber Bragg gratings, interferometric Mach-Zehnder, and Fabry-Pérot configurations — and their recent developments are summarized.

Teixeira, João G. V.; Leite, Ivo T.; Silva, Susana; Frazão, Orlando

2014-09-01

355

Acoustic microscopy in the food industry  

NASA Astrophysics Data System (ADS)

Acoustic microscopy has been used for many years to image and measure the elastic properties of materials across a wide range of scientific disciplines. However the application of this technique in the food industry is scarce. In this paper we outline the operation of a reflection-mode acoustic microscope and discuss some of the issues relevant to its operation in the food sector. We then present two relevant case studies in which we employ acoustic microscopy to analyse potato cells and the fat structure in Iberian ham and chorizo.

Watson, N.; Povey, M.; Corona, E.; Benedito, J.; Parker, N.

2012-12-01

356

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

357

Acoustic Propagation Considerations for Underwater Acoustic Communications Network Development  

E-print Network

Acoustic Propagation Considerations for Underwater Acoustic Communications Network Development Woods Hole, MA 02543 jpreisig@whoi.edu ABSTRACT Underwater acoustic communications systems are challenged by the characteristics of acoustic propagation through the underwater environment

Zhou, Shengli

358

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

359

Flow Sorting and Sequencing Meadow Fescue Chromosome 4F1[C][W  

PubMed Central

The analysis of large genomes is hampered by a high proportion of repetitive DNA, which makes the assembly of short sequence reads difficult. This is also the case in meadow fescue (Festuca pratensis), which is known for good abiotic stress resistance and has been used in intergeneric hybridization with ryegrasses (Lolium spp.) to produce Festulolium cultivars. In this work, we describe a new approach to analyze the large genome of meadow fescue, which involves the reduction of sample complexity without compromising information content. This is achieved by dissecting the genome to smaller parts: individual chromosomes and groups of chromosomes. As the first step, we flow sorted chromosome 4F and sequenced it by Illumina with approximately 50× coverage. This provided, to our knowledge, the first insight into the composition of the fescue genome, enabled the construction of the virtual gene order of the chromosome, and facilitated detailed comparative analysis with the sequenced genomes of rice (Oryza sativa), Brachypodium distachyon, sorghum (Sorghum bicolor), and barley (Hordeum vulgare). Using GenomeZipper, we were able to confirm the collinearity of chromosome 4F with barley chromosome 4H and the long arm of chromosome 5H. Several new tandem repeats were identified and physically mapped using fluorescence in situ hybridization. They were found as robust cytogenetic markers for karyotyping of meadow fescue and ryegrass species and their hybrids. The ability to purify chromosome 4F opens the way for more efficient analysis of genomic loci on this chromosome underlying important traits, including freezing tolerance. Our results confirm that next-generation sequencing of flow-sorted chromosomes enables an overview of chromosome structure and evolution at a resolution never achieved before. PMID:24096412

Kopecký, David; Martis, Mihaela; ?íhalíková, Jarmila; H?ibová, Eva; Vrána, Jan; Bartoš, Jan; Kopecká, Jitka; Cattonaro, Federica; Sto?es, Št?pán; Novák, Petr; Neumann, Pavel; Macas, Ji?í; Šimková, Hana; Studer, Bruno; Asp, Torben; Baird, James H.; Navrátil, Petr; Karafiátová, Miroslava; Kubaláková, Marie; Šafá?, Jan; Mayer, Klaus; Doležel, Jaroslav

2013-01-01

360

Red nucleus and rubrospinal tract disorganization in the absence of Pou4f1.  

PubMed

The red nucleus (RN) is a neuronal population that plays an important role in forelimb motor control and locomotion. Histologically it is subdivided into two subpopulations, the parvocellular RN (pRN) located in the diencephalon and the magnocellular RN (mRN) in the mesencephalon. The RN integrates signals from motor cortex and cerebellum and projects to spinal cord interneurons and motor neurons through the rubrospinal tract (RST). Pou4f1 is a transcription factor highly expressed in this nucleus that has been related to its specification. Here we profoundly analyzed consequences of Pou4f1 loss-of-function in development, maturation and axonal projection of the RN. Surprisingly, RN neurons are specified and maintained in the mutant, no cell death was detected. Nevertheless, the nucleus appeared disorganized with a strong delay in radial migration and with a wider neuronal distribution; the neurons did not form a compacted population as they do in controls, Robo1 and Slit2 were miss-expressed. Cplx1 and Npas1, expressed in the RN, are transcription factors involved in neurotransmitter release, neuronal maturation and motor function processes among others. In our mutant mice, both transcription factors are lost, suggesting an abnormal maturation of the RN. The resulting altered nucleus occupied a wider territory. Finally, we examined RST development and found that the RN neurons were able to project to the spinal cord but their axons appeared defasciculated. These data suggest that Pou4f1 is necessary for the maturation of RN neurons but not for their specification and maintenance. PMID:25698939

Martinez-Lopez, Jesus E; Moreno-Bravo, Juan A; Madrigal, M Pilar; Martinez, Salvador; Puelles, Eduardo

2015-01-01

361

Opto-acoustic thrombolysis  

DOEpatents

This invention is a catheter-based device for generating an ultrasound excitation in biological tissue. Pulsed laser light is guided through an optical fiber to provide the energy for producing the acoustic vibrations. The optical energy is deposited in a water-based absorbing fluid, e.g. saline, thrombolytic agent, blood or thrombus, and generates an acoustic impulse in the fluid through thermoelastic and/or thermodynamic mechanisms. By pulsing the laser at a repetition rate (which may vary from 10 Hz to 100 kHz) an ultrasonic radiation field can be established locally in the medium. This method of producing ultrasonic vibrations can be used in vivo for the treatment of stroke-related conditions in humans, particularly for dissolving thrombus or treating vasospasm. The catheter can also incorporate thrombolytic drug treatments as an adjunct therapy and it can be operated in conjunction with ultrasonic detection equipment for imaging and feedback control and with optical sensors for characterization of thrombus type and consistency.

Celliers, Peter (Berkeley, CA); Da Silva, Luiz (Danville, CA); Glinsky, Michael (Livermore, CA); London, Richard (Orinda, CA); Maitland, Duncan (Livermore, CA); Matthews, Dennis (Moss Beach, CA); Fitch, Pat (Livermore, CA)

2000-01-01

362

C4F8O Pressurized Gas System for the Vhmpid R&d Studies  

NASA Astrophysics Data System (ADS)

The Very High Momentum Particle IDentification (VHMPID) detector has been proposed as one of ALICE upgrade to perform charged hadrons track-by-track identification in the range 5-25 GeV/c. The aim of this paper is to describe the design issues and technical aspects of the pressurized C4F8O radiator gas distribution system built for the VHMPID R&D studies. Such a system features an open pressure regulated and heated system which continuously purifies, distributes and monitors the gas radiator, remotely and safely.

de Cataldo, G.; Franco, A.; Pastore, C.; Sgura, I.

2014-06-01

363

4-[F-18]fluoroproline: A potential tracer for collagen synthesis. Radiosynthesis and biological evaluation  

SciTech Connect

Proline is an important constituent of the structural protein collagen. It has been shown that its fluorinated analogs (2S,4S)- and particularly (2S,4R)-4-fluoroproline are also incorporated into collagen (Gottlieb et al., Biochemistry (1965), 4: 2507). 4-[F-18]fluoroproline is therefore a potential probe for studying abnormal collagen synthesis e. g. in tumors, lung fibrosis and liver cirrhosis. We have evaluated the two diastereomeric forms using a transplantable osteosarcoma in mice as an in vivo model for elevated collagen synthesis, and a MCF 7 mamma carcinoma cell line for monolayer incubation studies.

Hamacher, K. [Institut fuer Nuklearchemie, KFA Juelich (Germany); Herz, M.; Truckenbrodt, R. [Nuklearmedizinische Klinik der TU Muenchen (Germany)] [and others

1996-05-01

364

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

365

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

366

Exploiting verdazyl radicals to assemble 2p-3d-4f one-dimensional chains.  

PubMed

A series of one dimensional chain complexes [Ln(hfac)3]2·[Cu(hfac)2]2·4(3pyvd)·n-C7H16 (Ln = Gd(), Tb(), Dy()) containing 2p, 3d and 4f spin carriers have been successfully synthesized and magnetically characterized where the verdazyl radicals represent the bridge linking copper(ii) and lanthanide(iii) ions. Rough estimation of magnetic behaviors of complex revealed that the coupling between a Gd(iii) ion and a radical is weakly ferromagnetic, while alternating-current susceptibilities of complexes and suggest no slow magnetic relaxations exist at low temperature. PMID:25689341

Wang, Chao; Lin, Shuang-Yan; Shi, Wei; Cheng, Peng; Tang, Jinkui

2015-03-10

367

Broadband enhanced transmission of acoustic waves through serrated metal gratings  

NASA Astrophysics Data System (ADS)

In this letter, we have demonstrated that serrated metal gratings, which introduce gradient coatings, can give rise to broadband transmission enhancement of acoustic waves. Here, we have experimentally and theoretically studied the acoustic transmission properties of metal gratings with or without serrated boundaries. The average transmission is obviously enhanced for serrated metal gratings within a wide frequency range, while the Fabry-Perot resonance is significantly suppressed. An effective medium hypothesis with varying acoustic impedance is proposed to analyze the mechanism, which was verified through comparison with finite-element simulation. The serrated boundary supplies gradient mass distribution and gradient normal acoustic impedance, which could efficiently reduce the boundary reflection. Further, by increasing the region of the serrated boundary, we present a broadband high-transmission grating for wide range of incident angle. Our results may have potential applications to broadband acoustic imaging, acoustic sensing, and acoustic devices.

Qi, Dong-Xiang; Deng, Yu-Qiang; Xu, Di-Hu; Fan, Ren-Hao; Peng, Ru-Wen; Chen, Ze-Guo; Lu, Ming-Hui; Huang, X. R.; Wang, Mu

2015-01-01

368

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

369

New flow boiling heat transfer correlation for CFC-114 and C{sub 4}F{sub 10}  

SciTech Connect

The flow boiling tests being conducted at Cudo Technologies, Ltd. in Lexington, Kentucky are a part of The GDP Coolant Replacement Project. The tests are to be done with two alternates, C{sub 4}F{sub 10} and C{sub 4}F{sub 8}, as well as CFC-114. So far, tests were conducted with CFC-114 and C{sub 4}F{sub 10}. The CFC-114 data by Cudo shows better heat transfer performance than that predicted by the codes used in the numerical model which were based on a superposition model. The data was applied to an asymptotic model developed by Steiner and Taborek. The new correlation developed seems to fit better with the Cudo data as well as the Paducah cell test data. The model will be further investigated when C{sub 4}F{sub 8} data is available.

Szady, A.J. [Oak Ridge National Lab., TN (United States). Engineering Technology Div.

1995-08-01

370

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

371

Scanning acoustic microscopy for mapping the microstructure of soft materials  

E-print Network

Acoustics provides a powerful modality with which to 'see' the mechanical properties of a wide range of elastic materials. It is particularly adept at probing soft materials where excellent contrast and propagation distance can be achieved. We have constructed a scanning acoustic microscope capable of mapping the microstructure of such materials. We review the general principles of scanning acoustic microscopy and present new examples of its application in imaging biological matter, industrial materials and particulate systems.

N. G. Parker; M. J. W. Povey

2009-04-30

372

3d-4f magnetic interaction with density functional theory plus u approach: local Coulomb correlation and exchange pathways.  

PubMed

The 3d-4f exchange interaction plays an important role in many lanthanide based molecular magnetic materials such as single-molecule magnets and magnetic refrigerants. In this work, we study the 3d-4f magnetic exchange interactions in a series of Cu(II)-Gd(III) (3d(9)-4f(7)) dinuclear complexes based on the numerical atomic basis-norm-conserving pseudopotential method and density functional theory plus the Hubbard U correction approach (DFT+U). We obtain improved description of the 4f electrons by including the semicore 5s5p states in the valence part of the Gd-pseudopotential. The Hubbard U correction is employed to treat the strongly correlated Cu-3d and Gd-4f electrons, which significantly improve the agreement of the predicted exchange constants, J, with experiment, indicating the importance of accurate description of the local Coulomb correlation. The high efficiency of the DFT+U approach enables us to perform calculations with molecular crystals, which in general improve the agreement between theory and experiment, achieving a mean absolute error smaller than 2 cm(-1). In addition, through analyzing the physical effects of U, we identify two magnetic exchange pathways. One is ferromagnetic and involves an interaction between the Cu-3d, O-2p (bridge ligand), and the majority-spin Gd-5d orbitals. The other one is antiferromagnetic and involves Cu-3d, O-2p, and the empty minority-spin Gd-4f orbitals, which is suppressed by the planar Cu-O-O-Gd structure. This study demonstrates the accuracy of the DFT+U method for evaluating the 3d-4f exchange interactions, provides a better understanding of the exchange mechanism in the Cu(II)-Gd(III) complexes, and paves the way for exploiting the magnetic properties of the 3d-4f compounds containing lanthanides other than Gd. PMID:24274078

Zhang, Yachao; Yang, Yang; Jiang, Hong

2013-12-12

373

Synthesis and electrochemical performance of Li2Co1? xMxPO4F (M = Fe, Mn) cathode materials  

PubMed Central

Summary In the search for high-energy materials, novel 3D-fluorophosphates, Li2Co1? xFexPO4F and Li2Co1? xMnxPO4F, have been synthesized. X-ray diffraction and scanning electron microscopy have been applied to analyze the structural and morphological features of the prepared materials. Both systems, Li2Co1? xFexPO4F and Li2Co1? xMnxPO4F, exhibited narrow ranges of solid solutions: x ? 0.3 and x ? 0.1, respectively. The Li2Co0.9Mn0.1PO4F material demonstrated a reversible electrochemical performance with an initial discharge capacity of 75 mA·h·g?1 (current rate of C/5) upon cycling between 2.5 and 5.5 V in 1 M LiBF4/TMS electrolyte. Galvanostatic measurements along with cyclic voltammetry supported a single-phase de/intercalation mechanism in the Li2Co0.9Mn0.1PO4F material. PMID:24367755

Drozhzhin, Oleg A; Fedotov, Stanislav S; Storozhilova, Darya A; Panin, Rodion V; Antipov, Evgeny V

2013-01-01

374

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 ...

375

Acoustic emission frequency discrimination  

NASA Technical Reports Server (NTRS)

In acoustic emission nondestructive testing, broadband frequency noise is distinguished from narrow banded acoustic emission signals, since the latter are valid events indicative of structural flaws in the material being examined. This is accomplished by separating out those signals which contain frequency components both within and beyond (either above or below) the range of valid acoustic emission events. Application to acoustic emission monitoring during nondestructive bond verification and proof loading of undensified tiles on the Space Shuttle Orbiter is considered.

Sugg, Frank E. (inventor); Graham, Lloyd J. (inventor)

1988-01-01

376

An Acoustic Charge Transport Imager for High Definition Television Applications: Low-Voltage SAW Amplifiers on Multilayer GaAs/ZnO Substrates  

NASA Technical Reports Server (NTRS)

This thesis addresses the acoustoelectric issues concerning the amplification of surface acoustic waves (SAWs) and the reflection of SAWs from slanted reflector gratings on GaAs, with application to a novel acoustic charge transport (ACT) device architecture. First a simple model of the SAWAMP was developed, which was subsequently used to define the epitaxially grown material structure necessary to provide simultaneously high resistance and high electron mobility. In addition, a segmented SAWAMP structure was explored with line widths on the order of an acoustic wavelength. This resulted in the demonstration of SAWAMPS with an order of magnitude less voltage and power requirements than previously reported devices. A two-dimensional model was developed to explain the performance of devices with charge confinement layers less then 0.5 mm, which was experimentally verified. This model was extended to predict a greatly increased gain from the addition of a ZnO overlay. These overlays were experimentally attempted, but no working devices were reported due to process incompatibilities. In addition to the SAWAMP research, the reflection of SAWs from slanted gratings on GaAs was also studied and experimentally determined reflection coefficients for both 45 deg grooves and Al stripes on GaAs have been reported for the first time. The SAWAMp and reflector gratings were combined to investigate the integrated ring oscillator for application to the proposed ACT device and design parameters for this device have been provided.

Hunt, W. D.; Brennan, K. F.; Summers, C. J.; Cameron, Thomas P.

1996-01-01

377

Shallow water acoustic networks  

Microsoft Academic Search

Underwater acoustic networks are generally formed by acoustically connected ocean bottom sensor nodes, autonomous underwater vehicles (AUVs), and surface stations that serve as gateways and provide radio communication links to on-shore stations. The quality of service of such networks is limited by the low bandwidth of acoustic transmission channels, high latency resulting from the slow propagation of sound, and elevated

John G. Proakis; Ethem M. Sozer; Joseph A. Rice; M. Stojanovic

2001-01-01

378

Acoustics and Vibration Animations  

NSDL National Science Digital Library

The links contained contain animations which visualize certain concepts concerning acoustics and vibration. The choice of animations coincides with topics covered in the courses PHYS-382, Acoustics I: Sounds and Sources, and PHYS-482, Acoustics II: Sound and Vibration, which the author teaches at Kettering University.

Daniel Russell

379

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

380

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

381

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

382

Self-Assembly of Hexanuclear Clusters of 4f and 5f Elements with Cation Specificity  

SciTech Connect

Six hexanuclear clusters of 4f and 5f elements were synthesized by room-temperature slow concentration experiments. Cerium(IV), thorium(IV), and plutonium(IV) each form two different hexanuclear clusters, among which the cerium and plutonium clusters are isotypic, whereas the thorium clusters show more diversity. The change in ionic radii of approximately 0.08 Å between these different metal ions tunes the cavity size so that NH{sub 4}{sup +} (1.48 Å) has the right dimensions to assemble the cerium and plutonium clusters, whereas Cs{sup +} (1.69 Å) is necessary to assemble the thorium clusters. If these cations are not used in the reactions, only amorphous material is obtained.

Diwu, J.; Good, Justin J.; DiStefano, Victoria H.; Albrecht-Schmitt, Thomas E.

2011-01-01

383

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

PubMed Central

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. PMID:20457945

Nair, Sunil; Stockert, O.; Witte, U.; Nicklas, M.; Schedler, R.; Kiefer, K.; Thompson, J. D.; Bianchi, A. D.; Fisk, Z.; Wirth, S.; Steglich, F.

2010-01-01

384

Altered leukotriene B4 metabolism in CYP4F18-deficient mice does not impact inflammation following renal ischemia.  

PubMed

Inflammatory responses to infection and injury must be restrained and negatively regulated to minimize damage to host tissue. One proposed mechanism involves enzymatic inactivation of the pro-inflammatory mediator leukotriene B4, but it is difficult to dissect the roles of various metabolic enzymes and pathways. A primary candidate for a regulatory pathway is omega oxidation of leukotriene B4 in neutrophils, presumptively by CYP4F3A in humans and CYP4F18 in mice. This pathway generates ?, ?-1, and ?-2 hydroxylated products of leukotriene B4, depending on species. We created mouse models targeting exons 8 and 9 of the Cyp4f18 allele that allows both conventional and conditional knockouts of Cyp4f18. Neutrophils from wild-type mice convert leukotriene B4 to 19-hydroxy leukotriene B4, and to a lesser extent 18-hydroxy leukotriene B4, whereas these products were not detected in neutrophils from conventional Cyp4f18 knockouts. A mouse model of renal ischemia-reperfusion injury was used to investigate the consequences of loss of CYP4F18 in vivo. There were no significant changes in infiltration of neutrophils and other leukocytes into kidney tissue as determined by flow cytometry and immunohistochemistry, or renal injury as assessed by histological scoring and measurement of blood urea nitrogen. It is concluded that CYP4F18 is necessary for omega oxidation of leukotriene B4 in neutrophils, and is not compensated by other CYP enzymes, but loss of this metabolic pathway is not sufficient to impact inflammation and injury following renal ischemia-reperfusion in mice. PMID:24632148

Winslow, Valeria; Vaivoda, Rachel; Vasilyev, Aleksandr; Dombkowski, David; Douaidy, Karim; Stark, Christopher; Drake, Justin; Guilliams, Evin; Choudhary, Dharamainder; Preffer, Frederic; Stoilov, Ivaylo; Christmas, Peter

2014-06-01

385

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

386

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

387

Acoustical standards news.  

PubMed

American National Standards (ANSI Standards) developed by Accredited Standards Committees S1, S2, S3, and S12 in the areas of acoustics, mechanical vibration and shock, 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 Standards home page: http://acousticalsociety.org/standards. PMID:25786973

Blaeser, Susan B; Schomer, Paul D

2015-03-01

388

Human CYP4F3s are the main catalysts in the oxidation of fatty acid epoxides.  

PubMed

CYP4F isoforms are involved in the oxidation of important cellular mediators such as leukotriene B4 (LTB4) and prostaglandins. The proinflammatory agent LTB4 and cytotoxic leukotoxins have been associated with several inflammatory diseases. We present evidence that the hydroxylation of Z 9(10)-epoxyoctadecanoic, Z 9(10)-epoxyoctadec-Z 12-enoic, and Z 12(13)-epoxyoctadec-Z 9-enoic acids and that of monoepoxides from arachidonic acid [epoxyeicosatrienoic acid (EET)] is important in the regulation of leukotoxin and EET activity. These three epoxidized derivatives from the C18 family (C18-epoxides) were converted to 18-hydroxy-C18-epoxides by human hepatic microsomes with apparent Km values of between 27.6 and 175 microM. Among recombinant P450 enzymes, CYP4F2 and CYP4F3B catalyzed mainly the omega-hydroxylation of C18-epoxides with an apparent Vmax of between 0.84 and 15.0 min(-1), whereas the apparent Vmax displayed by CYP4F3A, the isoform found in leukocytes, ranged from 3.0 to 21.2 min(-1). The rate of omega-hydroxylation by CYP4A11 was experimentally found to be between 0.3 and 2.7 min(-1). CYP4F2 and CYP4F3 exhibited preferences for omega-hydroxylation of Z 8(9)-EET, whereas human liver microsomes preferred Z 11(12)-EET and, to a lesser extent, Z 8(9)-EET. Moreover, vicinal diol from both C18-epoxides and EETs were omega-hydroxylated by liver microsomes and by CYP4F2 and CYP4F3. These data support the hypothesis that the human CYP4F subfamily is involved in the omega-hydroxylation of fatty acid epoxides. These findings demonstrate that another pathway besides conversion to vicinal diol or chain shortening by beta-oxidation exists for fatty acid epoxide inactivation. PMID:15145985

Le Quéré, Valérie; Plée-Gautier, Emmanuelle; Potin, Philippe; Madec, Stéphanie; Salaün, Jean-Pierre

2004-08-01

389

Two transcription factors, Pou4f2 and Isl1, are sufficient to specify the retinal ganglion cell fate.  

PubMed

As with other retinal cell types, retinal ganglion cells (RGCs) arise from multipotent retinal progenitor cells (RPCs), and their formation is regulated by a hierarchical gene-regulatory network (GRN). Within this GRN, three transcription factors-atonal homolog 7 (Atoh7), POU domain, class 4, transcription factor 2 (Pou4f2), and insulin gene enhancer protein 1 (Isl1)-occupy key node positions at two different stages of RGC development. Atoh7 is upstream and is required for RPCs to gain competence for an RGC fate, whereas Pou4f2 and Isl1 are downstream and regulate RGC differentiation. However, the genetic and molecular basis for the specification of the RGC fate, a key step in RGC development, remains unclear. Here we report that ectopic expression of Pou4f2 and Isl1 in the Atoh7-null retina using a binary knockin-transgenic system is sufficient for the specification of the RGC fate. The RGCs thus formed are largely normal in gene expression, survive to postnatal stages, and are physiologically functional. Our results indicate that Pou4f2 and Isl1 compose a minimally sufficient regulatory core for the RGC fate. We further conclude that during development a core group of limited transcription factors, including Pou4f2 and Isl1, function downstream of Atoh7 to determine the RGC fate and initiate RGC differentiation. PMID:25775587

Wu, Fuguo; Kaczynski, Tadeusz J; Sethuramanujam, Santhosh; Li, Renzhong; Jain, Varsha; Slaughter, Malcolm; Mu, Xiuqian

2015-03-31

390

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.

391

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

392

Photoacoustic imaging platforms for multimodal imaging  

PubMed Central

Photoacoustic (PA) imaging is a hybrid biomedical imaging method that exploits both acoustical Epub ahead of print and optical properties and can provide both functional and structural information. Therefore, PA imaging can complement other imaging methods, such as ultrasound imaging, fluorescence imaging, optical coherence tomography, and multi-photon microscopy. This article reviews techniques that integrate PA with the above imaging methods and describes their applications. PMID:25754364

2015-01-01

393

Surface resonant states and superlensing in acoustic metamaterials  

NASA Astrophysics Data System (ADS)

We report that the negative material responses of acoustic metamaterials can lead to a plethora of surface resonant states. We determine that negative effective-mass density is the necessary condition for the existence of surface states on acoustic metamaterials. We offer the microscopic picture of these unique surface states; in addition, we find that these surface excitations enhance the transmission of evanescent pressure fields across the metamaterial. The evanescent pressure fields scattered from an object can be resonantly coupled and enhanced at the surface of the acoustic metamaterial, resulting in an image with resolution below the diffraction limit. This concept of acoustic superlens opens exciting opportunities to design acoustic metamaterials for ultrasonic imaging.

Ambati, Muralidhar; Fang, Nicholas; Sun, Cheng; Zhang, Xiang

2007-05-01

394

Images  

Cancer.gov

Home News and Events Multimedia Library Images Images:  Cancer Biology Image: Cell with DNA 72 DPI | 300 DPIDrawing depicting DNA molecule unwinding from a chromosome inside the nucleus of a cell. NHGRI >> View All Cancer Pathology/Imaging Image: Female

395

A 4F2-cross-point phase change memory using nano-crystalline doped GeSbTe material  

NASA Astrophysics Data System (ADS)

This paper reports on the use of nano-crystalline doped GeSbTe, or nano-GST, to fabricate a cross-point phase change memory with 4F2 cell size and test results obtained for it. We show the characteristics of a poly-Si diode select device with a high on–off ratio and data writing in a 4F2 memory cell array. The advantages of nano-GST over conventional GeSbTe are presented in terms of neighboring disturbance and 4F2 cross-point array formation. The memory cells’ high drivability, low power, and selective write and read performances are demonstrated. The scalability of the diode current density is also presented.

Takaura, Norikatsu; Kinoshita, Masaharu; Tai, Mitsuharu; Ohyanagi, Takasumi; Akita, Kenichi; Morikawa, Takahiro

2015-04-01

396

Acoustic Translation of an Acoustically Levitated Sample  

NASA Technical Reports Server (NTRS)

Acoustic-levitation apparatus uses only one acoustic mode to move sample from one region of chamber to another. Sample heated and cooled quickly by translation between hot and cold regions of levitation chamber. Levitated sample is raised into furnace region by raising plunger. Frequency of sound produced by transducers adjusted by feedback system to maintain (102) resonant mode, which levitates sample midway between transducers and plunger regardless of plunger position.

Barmatz, M. B.; Allen, J. L.

1986-01-01

397

DIGITAL DYNAMIC FOCUSSING OF AN ACOUSTIC TRANSDUCER  

Microsoft Academic Search

In acoustic imaging there is a tradeoff between resolution and depth of focus. Obtaining high resolution requires strong focussing which results in a small focal depth. To achieve good depth of focus requires weaker focussing, with a corresponding loss of resolution. In pulse echo systems, this may be alleviated to a certain extent by transmitting a weakly focussed pulse which

D. G. Bailey; G. Wade

398

Measurement of swarm parameters of cC 4 F 8 \\/CO 2 and its insulation characteristics analysis  

Microsoft Academic Search

In c-C4F8 and c-C4F8\\/CO2 mixtures, the swarm parameters including ionization coefficient, attachment coefficient and effective ionization coefficient\\u000a were obtained at the ratio of the electric field strength to the gas density between 150–550 Td by the steady-state Townsend\\u000a (SST) method. Static breakdown voltages at each ratio were also measured at the SST condition. The limiting field strengths\\u000a were obtained by

Liu-chun Zhang; Deng-ming Xiao; Dong Zhang; Bian-tao Wu

2008-01-01

399

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

400

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

401

Infratentorial approach to internal acoustic meatus.  

PubMed

Surgical exposure of internal acoustic meatus via typical suboccipital retrosigmoid craniotomy is limited by inner ear structures that should remain intact if hearing preservation is attempted. Feasibility of supracerebellar-infratentorial approach to the meatus with more medial angle of exposure and with preservation of inner ear structures was studied on fresh cadavers and on computed tomography pictures of temporal bones. Anatomical relationships of internal acoustic meatus and adjacent structures show marked individual variability. When typical retrosigmoid craniotomy is used to expose meatal fundus, significant medial retraction of cerebellar hemisphere is required in 47% of the patients to avoid opening endolymphatic spaces. Internal acoustic foramen and meatus can be exposed via craniotomy situated under transverse sinus, with 10-15 mm downward retraction of cerebellum. Medial extent of craniotomy can be planned on preoperative imaging studies. Infratentorial supracerebellar exposure of internal acoustic meatus allows for more medial angle of surgical approach than standard retrosigmold craniotomy. It can be used when preoperative imaging studies show that anatomical relationships between internal acoustic meatus and inner ear structures would require excessive cerebellar retraction to visualize a whole tumor inside meatus. PMID:17171122

Krajewski, R; Kukwa, A

1999-01-01

402

Underwater acoustic networks  

Microsoft Academic Search

With the advances in acoustic modem technology that enabled high-rate reliable communications, current research focuses on communication between various remote instruments within a network environment. Underwater acoustic (UWA) networks are generally formed by acoustically connected ocean-bottom sensors, autonomous underwater vehicles, and a surface station, which provides a link to an on-shore control center. While many applications require long-term monitoring of

Ethem M. Sozer; Milica Stojanovic; John G. Proakis

2000-01-01

403

Acoustic Levitator Maintains Resonance  

NASA Technical Reports Server (NTRS)

Transducer loading characteristics allow resonance tracked at high temperature. Acoustic-levitation chamber length automatically adjusted to maintain resonance at constant acoustic frequency as temperature changes. Developed for containerless processing of materials at high temperatures, system does not rely on microphones as resonance sensors, since microphones are difficult to fabricate for use at temperatures above 500 degrees C. Instead, system uses acoustic transducer itself as sensor.

Barmatz, M. B.; Gaspar, M. S.

1986-01-01

404

Variation of the electron attachment to n-C4F10 with temperature  

NASA Astrophysics Data System (ADS)

The total electron attachment rate constant ka() for n-C4F10 has been measured using an electron swarm technique in the mean electron energy, , range 0.76 to 4.81 eV and over the temperature, T, range 300 to 750 K. The measured ka(,T) and the total electron attachment cross section ?a(?,T) determined from these by unfolding are reported. The ka() first decrease slowly with T between 300 and 400 K, then decrease precipitously between 400 and ˜500 K, and subsequently increase for T>500 K. The overall variation of ka with T depends on . From the measured dependence of ka() on the total gas number density and T we determined the contribution of dissociative and nondissociative attachment to ka as a function of ; the contribution of nondissociative attachment decreases with T and the contribution of dissociative attachment increases with T. The ratio Rd/t of the dissociative to the total electron attachment is small at low and T, but it increases with both and T and reaches unity for T>500 K and >1.7 eV. These results are discussed in relation to similar earlier work on C2F6 and C3F8.

Datskos, P. G.; Christophorou, L. G.

1987-02-01

405

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

406

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

407

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

408

A Study of EUV Line Emission from the O4f Star Zeta Puppis  

NASA Astrophysics Data System (ADS)

We propose a 140 ks EUVE SW Spectrometer observation of the O4f star, Zeta Puppis. Due to its low ISM column density and highly ionized stellar wind, a unique EUV window is accessible for viewing between 128-140 A, SUGGESTING THAT THIS STAR MAY BE THE ONLY O STAR OBSERVABLE WITH THE EUVE. The major objective of this proposal is straightforward; a positive detection will provide a yes or no answer. A long withstanding problem in OB stars concerns the spatial location of the X-ray source. Our modelling efforts suggest that the strength of observable EUV radiation will provide very strong constraints on the location of the X-ray source; the stronger the EUV flux, the more deeply embedded is the X-ray source. Whereas, a detection would rule out the possibility that the X-ray emission is deeply embedded in the stellar wind. For the deeply embedded X-ray source model, we present a simulated EUVE SW spectrum which shows that a significant S/N is predicted. Our simulation predicts that three emission lines should be detected (OV 135.8A; FeVIII 131A; MgV 132.5A). If the weaker Fe and Mg lines are detected, we will also be able to test a recent ASCA SIS prediction; Fe and Mg abundances appear to be significantly non-solar.

Waldron, Wayne Lee

409

The adenovirus E1A-regulated transcription factor E4F is generated from the human homolog of nuclear factor phiAP3.  

PubMed Central

A 50-kDa cellular factor, E4F, has been implicated in mediating trans activation of the adenovirus E4 gene by the 289R E1A(13S) protein. Previous experiments demonstrated an E1A-dependent increase in E4F DNA binding activity, dependent on phosphorylation, that correlated with the activation of E4 transcription. Using expression screening, we isolated a cDNA clone encoding the E4F protein, as judged by DNA binding characteristics, transcriptional activation, and immunological criteria. The E4F-1 cDNA encodes a 783-amino-acid polypeptide that has 86% sequence identity with the murine nuclear factor phiAP3, a GLI-krüppel-related protein. E4F DNA binding activity is encoded within an amino-terminal region of E4F-1 that contains a zinc finger domain and, as with endogenous E4F, is phosphatase sensitive. We found that E4F was generated from the full-length E4F-1-encoded protein as a 50-kDa amino-terminal fragment. Moreover, E1A(13S) expression induced the phosphorylation of both forms of E4F-1 but differentially regulated their DNA binding activities, stimulating the 50-kDa fragment while reducing the activity of the full-length protein. In transient-transfection assays, the E4F-1 amino-terminal fragment stimulated the adenovirus E4 promoter in the presence of E1A(13S), whereas the full-length protein repressed the promoter in the absence, but not the presence, of E1A. The results indicate that the 50-kDa polypeptide responsible for E4F DNA binding activity is a fragment generated from the human homolog of phiAP3 and that the two forms of the E4F-1 protein are differentially regulated by E1A through phosphorylation. PMID:9121437

Fernandes, E R; Rooney, R J

1997-01-01

410

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

411

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....

412

Acoustic Levitation With Less Equipment  

NASA Technical Reports Server (NTRS)

Certain chamber shapes require fewer than three acoustic drivers. Levitation at center of spherical chamber attained using only one acoustic driver. Exitation of lowest spherical mode produces asymmetric acoustic potential well.

Barmatz, M. B.; Jacobi, N.

1983-01-01

413

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

414

Acoustic superfocusing by solid phononic crystals  

NASA Astrophysics Data System (ADS)

We propose a solid phononic crystal lens capable of acoustic superfocusing beyond the diffraction limit. The unit cell of the crystal is formed by four rigid cylinders in a hosting material with a cavity arranged in the center. Theoretical studies reveal that the solid lens produces both negative refraction to focus propagating waves and surface states to amplify evanescent waves. Numerical analyses of the superfocusing effect of the considered solid phononic lens are presented with a separated source excitation to the lens. In this case, acoustic superfocusing beyond the diffraction limit is evidenced. Compared to the fluid phononic lenses, the solid lens is more suitable for ultrasonic imaging applications.

Zhou, Xiaoming; Assouar, M. Badreddine; Oudich, Mourad

2014-12-01

415

An acoustic filter based on layered structure  

NASA Astrophysics Data System (ADS)

Acoustic filters (AFs) are key components to control wave propagation in multi-frequency systems. We present a design which selectively achieves acoustic filtering with a stop band and passive amplification at the high- and low-frequencies, respectively. Measurement results from the prototypes closely match the design predictions. The AF suppresses the high frequency aliasing echo by 14.5 dB and amplifies the low frequency transmission by 8.0 dB, increasing an axial resolution from 416 to 86 ?m in imaging. The AF design approach is proved to be effective in multi-frequency systems.

Ma, Jianguo; Steer, Michael B.; Jiang, Xiaoning

2015-03-01

416

A novel frameshift mutation of POU4F3 gene associated with autosomal dominant non-syndromic hearing loss  

SciTech Connect

Autosomal dominant mutations in the transcription factor POU4F3 gene are associated with non-syndromic hearing loss in humans; however, there have been few reports of mutations in this gene worldwide. We performed a mutation analysis of the POU4F3 gene in 42 unrelated Koreans with autosomal dominant non-syndromic hearing loss, identifying a novel 14-bp deletion mutation in exon 2 (c.662del14) in one patient. Audiometric examination revealed severe bilateral sensorineural hearing loss in this patient. The novel mutation led to a truncated protein that lacked both functional POU domains. We further investigated the functional distinction between wild-type and mutant POU4F3 proteins using in vitro assays. The wild-type protein was completely localized in the nucleus, while the truncation of protein seriously affected its nuclear localization. In addition, the mutant failed to activate reporter gene expression. This is the first report of a POU4F3 mutation in Asia, and moreover our data suggest that further investigation will need to delineate ethnicity-specific genetic background for autosomal dominant non-syndromic hearing loss within Asian populations.

Lee, Hee Keun [Department of Biology, College of Natural Sciences, Kyungpook National University, Daegu (Korea, Republic of)] [Department of Biology, College of Natural Sciences, Kyungpook National University, Daegu (Korea, Republic of); Park, Hong-Joon [Soree Ear Clinic, Seoul (Korea, Republi