Sample records for acoustic 4f imaging

  1. 3D photoacoustic imaging system with 4F acoustic lens

    Microsoft Academic Search

    En Jen; Hsintien Lin; Huihua Kenny Chiang

    2011-01-01

    Photoacoustic imaging (PAI) has several advantages in achieving high-contrast imaging of blood vessels or tumors over conventional ultrasound imaging. However, most PAI systems use conventional linear array transducers and need complex algorithms to reconstruct photoacoustic (PA) tomography or three-dimensional images. In this research, we successfully demonstrated the use of a 4F acoustic lens to realize 3D PAI system. The 3D

  2. Photoacoustic tomography imaging based on a 4f acoustic lens imaging system

    Microsoft Academic Search

    Zhanxu Chen; Zhilie Tang; Wei Wan

    2007-01-01

    The theory of photoacoustic tomography (PAT) imaging using a 4f acoustic lens imaging system has been investigated, and the theoretical results show that a 4f acoustic lens has the ability of imaging and guarantees axial and lateral unit magnification of image. A system, a 4f acoustic lens imaging system combining with time-resolved technique, is developed to acquire PAT images. The

  3. Photoacoustic tomography imaging based on a 4f acoustic lens imaging system.

    PubMed

    Chen, Zhanxu; Tang, Zhilie; Wan, Wei

    2007-04-16

    The theory of photoacoustic tomography (PAT) imaging using a 4f acoustic lens imaging system has been investigated, and the theoretical results show that a 4f acoustic lens has the ability of imaging and guarantees axial and lateral unit magnification of image. A system, a 4f acoustic lens imaging system combining with time-resolved technique, is developed to acquire PAT images. The 4f acoustic lens is able to image initial photoacoustic (PA) pressure distribution, which exactly resembles the absorption distribution, onto an imaging plane. Combining with time-resolved technique, the linear transducer array is adopted to acquire the PA pressure distribution to reconstruct the PAT images. Experimental results demonstrate that the system is able to obtain PAT images and the images contrast sharply with their backgrounds. PMID:19532746

  4. Photoacoustic tomography imaging using a 4f acoustic lens and peak-hold technology.

    PubMed

    Wei, Yadong; Tang, Zhilie; Zhang, Hanchao; He, Yongheng; Liu, Haifeng

    2008-04-14

    In this paper we present a new high-contrast photoacoustic tomography (PAT) imaging system using a 4f acoustic lens, a 64-element linear transducer array and peak-hold technology. This PAT imaging system has been developed to obtain three-dimensional (3D) PAT images of experimental samples. By utilizing a 4f acoustic lens, the photoacoustic (PA) signals generated from the sample are directly imaged on the imaging plane and collected by the 64-element linear transducer array, which changes them into the corresponding electronic signals. Then we can get one-dimensional (1D) images from the electronic signals using a peak detection-and-hold circuit. After vertical scanning with a stepping motor on the imaging plane, a 2D PA image of the sample is successfully obtained. Combined with the time-resolved technique, we can then get 3D PAT images. The results show that the reconstructed images agree well with the original samples. PMID:18542633

  5. 4F8 Image Coding Course 1 4F8 Image Coding Course

    E-print Network

    Kingsbury, Nick

    , S Regunathan, and H Malvar, Low-complexity hierarchical lapped transform for lossy-to-lossless image coding 11 2.1 The Haar transform . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 2-level Haar Transform . . . . . . . . . . . . . . . . . . . . . . . . 17 2.4 Use of Laplacian PDFs in Image

  6. Nondestructive Acoustic Imaging Techniques

    Microsoft Academic Search

    Volker Schmitz

    2002-01-01

    Acoustic imaging techniques are used in the field of nondestructive testing of technical components to measure defects such\\u000a as lack of side wall fusion or cracks in welded joints. Data acquisition is performed by a remote-controlled manipulator and\\u000a a PC for the mass storage of the high-frequency time-of-flight data at each probe position. The quality of the acoustic images\\u000a and

  7. Nondestructive Acoustic Imaging Techniques

    NASA Astrophysics Data System (ADS)

    Schmitz, Volker

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

  8. Acoustic subwavelength imaging of subsurface objects with acoustic resonant metalens

    SciTech Connect

    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

    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.

  9. Acoustic imaging system

    NASA Technical Reports Server (NTRS)

    Kendall, J. M., Jr.

    1977-01-01

    Tool detects noise sources by scanning sound "scene" and displaying relative location of noise-producing elements in area. System consists of ellipsoidal acoustic mirror and microphone and a display device.

  10. Underwater acoustic \\/ optical imaging system

    Microsoft Academic Search

    Haisen Li; Jian Xu; Tian Zhou; Pingxuan Dou

    2010-01-01

    This paper introduces an underwater acoustic \\/ optical integrated imaging system, which individual uses the DSP core and ARM core of the OMAP3530 processor to realize the multi-subarray amplitude-phase united detection algorithm and optical camera image collection for getting the estimating the depth of the sea and the optical information of the focus area uses the ARM core to receive

  11. Acoustic Waves in Medical Imaging and Diagnostics

    PubMed Central

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

    2013-01-01

    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

  12. Acoustic imaging microscope

    DOEpatents

    Deason, Vance A.; Telschow, Kenneth L.

    2006-10-17

    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.

  13. Reflective echo tomographic imaging using acoustic beams

    DOEpatents

    Kisner, Roger; Santos-Villalobos, Hector J

    2014-11-25

    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.

  14. The imaging property of photoacoustic Fourier imaging and tomography using an acoustic lens imaging system

    Microsoft Academic Search

    Wei Wan; Ruisheng Liang; Zhilie Tang; Zhanxu Chen; Hanchao Zhang; Yongheng He

    2007-01-01

    The theory of photoacoustic tomography imaging using an acoustic lens imaging system has been investigated, and the photoacoustic (PA) Fourier imaging property of an acoustic lens is presented. The theoretical results show that an acoustic lens is able to realize two-dimensional PA Fourier imaging and the focal depth of the acoustic lens is 20 mm. The PA signals with the

  15. Underwater imaging with a moving acoustic lens

    Microsoft Academic Search

    Behzad Kamgar-parsi; Lawrence J. Rosenblum; Edward O. Belcher

    1998-01-01

    The acoustic lens is a high-resolution, forward-looking sonar for three dimensional (3-D) underwater imaging. We discuss processing the lens data for recreating and visualizing the scene. Acoustical imaging, compared to optical imaging, is sparse and low resolution. To achieve higher resolution, we obtain a denser sample by mounting the lens on a moving platform and passing over the scene. This

  16. Acoustic 3D imaging of dental structures

    SciTech Connect

    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

    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.

  17. Real-time imaging of acoustic rectification

    NASA Astrophysics Data System (ADS)

    Danworaphong, S.; Kelf, T. A.; Matsuda, O.; Tomoda, M.; Tanaka, Y.; Nishiguchi, N.; Wright, O. B.; Nishijima, Y.; Ueno, K.; Juodkazis, S.; Misawa, H.

    2011-11-01

    We image gigahertz surface acoustic waves normally incident on a microscopic linear array of triangular holes—a generic "acoustic diode" geometry—with a real-time ultrafast optical technique. Spatiotemporal Fourier transforms reveal wave diffraction orders in k-space. Squared amplitude reflection and transmission coefficients for incidence on both sides of the array are evaluated and compared with numerical simulations. We thereby directly demonstrate acoustic rectification with an asymmetric structure.

  18. Ultrasonic liquid crystal-based underwater acoustic imaging

    Microsoft Academic Search

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

    1999-01-01

    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

  19. Acoustic Imaging of Combustion Noise

    NASA Technical Reports Server (NTRS)

    Ramohalli, K. N.; Seshan, P. K.

    1984-01-01

    Elliposidal acoustic mirror used to measure sound emitted at discrete points in burning turbulent jets. Mirror deemphasizes sources close to target source and excludes sources far from target. At acoustic frequency of 20 kHz, mirror resolves sound from region 1.25 cm wide. Currently used by NASA for research on jet flames. Produces clearly identifiable and measurable variation of acoustic spectral intensities along length of flame. Utilized in variety of monitoring or control systems involving flames or other reacting flows.

  20. Pulsed-Source Interferometry in Acoustic Imaging

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

    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").

  1. Seabed acoustic imaging in the surf zone

    Microsoft Academic Search

    S. G. Schock; H. Herrmann

    1996-01-01

    An acoustic technique for reflection profiling in the surf and nearshore zones is described that provides multiple-free images of beach sediments. Rectangular transmitting and receiving array apertures mounted under acoustic baffles eliminate water multiples when towed within 50 cm of the seabed. Multiple-free profiles of a beach in Cheasapeake Bay are generated in water depths of 8 meters to 0.3

  2. Imaging of Acoustic Waves in Sand

    SciTech Connect

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

    2003-08-01

    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.

  3. Digital holographic imaging for underwater acoustic applications

    Microsoft Academic Search

    G. A. Shippey; R. McHugh; J. G. Paul

    1992-01-01

    The technique described in this paper is primarily designed for underwater acoustic imaging. Incident wavefronts at an array aperture are sampled in space and time, then stored in a space-time memory, and used to reconstruct a 2D image fro a 1D array. It could similarly be used to reconstruct a 3D image from a 2D array. The technique is most

  4. High-resolution acoustical imaging

    Microsoft Academic Search

    Kent Edward Eschenberg

    1989-01-01

    Pressure waves, detected by an array of receivers, can be analyzed to determine the location of the acoustic source, or the location of objects which the waves encountered along their path. High resolution methods which use a linear array to locate stationary objects which have scattered the pressure waves are examined. Several methods are explored through simulations in air. A

  5. Simultaneous photoacoustic imaging technique using an acoustic imaging lens

    Microsoft Academic Search

    Xian Chen; Zhilie Tang; Yongheng He; Haifeng Liu; Yadong Wei; Yongbo Wu

    2009-01-01

    A simultaneous photoacoustic (PA) tomography imaging technique in multilayer samples was developed. Instead of using the PA image reconstruction methods on the basis of complex algorithms, obtaining a two-dimensional PA image in real time is available by using an acoustic lens that has the ability of parallel imaging. The imaging system can acquire the complete PA signals of high signal-to-noise

  6. Acoustic imaging of thick biological tissue

    Microsoft Academic Search

    Elena Maeva; Fedar Severin; Chiaki Miyasaka; Bernhard Tittmann; Roman Maev

    2009-01-01

    Up to now, biomedical imaging with ultrasound for observing a cellular tissue structure has been limited to very thinly sliced tissue at very high ultrasonic frequencies, i.e., 1 GHz. In this paper, we present the results of a systematic study to use a 150 to 200 MHz frequency range for thickly sliced biological tissue. A mechanical scanning reflection acoustic microscope

  7. ACOUSTIC DAYLIGHT IMAGING: VISION IN THE OCEAN

    Microsoft Academic Search

    Michael J. Buckingham; John R. Potter

    1994-01-01

    Sound provides a natural means for exploring the ocean but current sonar systems, as used for example in swath-mapping applications, do not provide directly pictorial images of the ocean depths. Such systems are more akin to radar, which relies on travel-time information to map the environment. A new acoustic technique for providing real-time visual images of the interior of the

  8. Imaging of acoustic charge transport in semiconductor heterostructures by surface acoustic waves

    E-print Network

    Ludwig-Maximilians-Universität, München

    Imaging of acoustic charge transport in semiconductor heterostructures by surface acoustic waves M on an otherwise unstructured semiconductor heterostructure. They have been extensively employed¨nchen, Germany A. O. Govorov Institute of Semiconductor Physics, Russian Academy of Sciences, Siberian Branch

  9. Holographic imaging of surface acoustic waves Francois Bruno,1

    E-print Network

    on an experimental demonstration of surface acoustic waves monitoring on a thin metal plate with heterodyne optical-field imaging of surface acoustic waves of nanometer amplitude can be achieved by optical holo- graphicHolographic imaging of surface acoustic waves Fran¸cois Bruno,1 J´er^ome Laurent,1 Daniel Royer,1

  10. 15 Acoustic Daylight Imaging in the Michael J. Buckingham

    E-print Network

    Buckingham, Michael

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

  11. Simultaneous photoacoustic imaging technique using an acoustic imaging lens.

    PubMed

    Chen, Xian; Tang, Zhilie; He, Yongheng; Liu, Haifeng; Wei, Yadong; Wu, Yongbo

    2009-01-01

    A simultaneous photoacoustic (PA) tomography imaging technique in multilayer samples was developed. Instead of using the PA image reconstruction methods on the basis of complex algorithms, obtaining a two-dimensional PA image in real time is available by using an acoustic lens that has the ability of parallel imaging. The imaging system can acquire the complete PA signals of high signal-to-noise ratio from all the object planes by utilizing the advantages of the acoustic lens with long focal depth and a fast data acquisition system with a high sampling rate. With the time-resolved technique, the PA signals from different object planes can be distinguished and then the high optical contrast multilayer PA images can be reconstructed simultaneously without any algorithms. The experimental results show that the reconstructed sections agree well with the original samples. PMID:19566292

  12. Adjustable acoustic knife edge for anisotropic and dark-field acoustic imaging

    Microsoft Academic Search

    Oleg Kolosov; Kazushi Yamanaka

    1994-01-01

    A new effective method for acoustic anisotropy and dark-field imaging in reflection ultrasonic focusing devices is proposed. Part of the spherical acoustic wave propagating to and coming from the object is stopped by an ultrasonically opaque acoustic knife edge (AKE) set at the aperture plane of the focusing lens or transducer. This method can be easily applied to commercially available

  13. Acoustic imaging of subtle porosity variations in ceramics

    NASA Technical Reports Server (NTRS)

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

    1988-01-01

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

  14. SPARSE UNDERWATER ACOUSTIC IMAGING: A CASE STUDY Nikolaos Stefanakis

    E-print Network

    Paris-Sud XI, Université de

    SPARSE UNDERWATER ACOUSTIC IMAGING: A CASE STUDY Nikolaos Stefanakis , Jacques Marchal , Valentin de Beaulieu 35042 Rennes Cedex, France ABSTRACT Underwater acoustic imaging is traditionally are (synthetically) formed at reception to form the image. We propose to exploit a natural sparsity prior to perform

  15. Method and apparatus for acoustic imaging of objects in water

    DOEpatents

    Deason, Vance A.; Telschow, Kenneth L.

    2005-01-25

    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.

  16. Acoustic and Photoacoustic Molecular Imaging of Cancer

    PubMed Central

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

    2014-01-01

    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

  17. Acoustic Mine Imaging (AMI) project: An underwater acoustic camera for use in mine warfare

    Microsoft Academic Search

    Colin Ellis; Ed Murphy

    2001-01-01

    This paper is submitted to detail the advances in sonar and imaging techniques and synthetic apertures being made in Australia by Thales Underwater Systems within a Australian Defence Acquisition Project termed Acoustic Mine Imaging (AMI). This paper will detail the development of the AMI underwater acoustic camera for the detection, classification and characterization of mines and other underwater objects in

  18. Quantitative Photo-Acoustic Imaging of Small Absorbers Habib Ammari

    E-print Network

    Kang, Hyeonbae

    Quantitative Photo-Acoustic Imaging of Small Absorbers Habib Ammari Emmanuel Bossy Vincent Jugnon Hyeonbae Kang§ December 1, 2009 Abstract In photo-acoustic imaging, energy absorption causes thermo absorber from the absorbed density. AMS subject classifications. 31B20, 35B37,35L05 Key words. photo

  19. Transthoracic Cardiac Acoustic Radiation Force Impulse Imaging

    NASA Astrophysics Data System (ADS)

    Bradway, David Pierson

    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.

  20. Adjustable acoustic knife edge for anisotropic and dark-field acoustic imaging

    NASA Astrophysics Data System (ADS)

    Kolosov, Oleg; Yamanaka, Kazushi

    1994-01-01

    A new effective method for acoustic anisotropy and dark-field imaging in reflection ultrasonic focusing devices is proposed. Part of the spherical acoustic wave propagating to and coming from the object is stopped by an ultrasonically opaque acoustic knife edge (AKE) set at the aperture plane of the focusing lens or transducer. This method can be easily applied to commercially available focusing systems and allows optimization of the setup for the microscopic study of various objects.

  1. Laser-induced acoustic imaging of underground objects

    NASA Astrophysics Data System (ADS)

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

    1999-02-01

    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.

  2. Determination of GaN solubility in supercritical ammonia with NH4F and NH4Cl mineralizer by in situ x-ray imaging of crystal dissolution

    NASA Astrophysics Data System (ADS)

    Schimmel, Saskia; Lindner, Michael; Steigerwald, Thomas G.; Hertweck, Benjamin; Richter, Theresia M. M.; Künecke, Ulrike; Alt, Nicolas S. A.; Niewa, Rainer; Schlücker, Eberhard; Wellmann, Peter J.

    2015-05-01

    Quantitative data on the solubility of GaN in supercritical ammonia using NH4F as mineralizer are reported. The solubility is determined by in situ x-ray imaging of the dissolution of GaN single crystals. First, solubility values obtained by this method with NH4Cl as mineralizer are presented and discussed with respect to existing literature data. Monitoring the dissolution process in situ reveals the time when the solubility limit is reached. Thus, it allows to distinguish the saturation of the solution from dissolution based on mass transport and deposition. This is a key advantage of solubility measurements by in situ x-ray imaging compared to gravimetric methods. Our results indicate that the solubility limit is reached much faster than usually assumed in gravimetric solubility studies and the solubility of GaN in ammonothermal media is significantly lower than reported so far.

  3. Optimization of a biometric system based on acoustic images.

    PubMed

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

    2014-01-01

    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

  4. Image reconstruction in photoacoustic tomography involving layered acoustic media.

    PubMed

    Schoonover, Robert W; Anastasio, Mark A

    2011-06-01

    Photoacoustic tomography (PAT), also known as thermoacoustic or optoacoustic tomography, is a rapidly emerging biomedical imaging technique that combines optical image contrast with ultrasound detection principles. Most existing reconstruction algorithms for PAT assume the object of interest possesses homogeneous acoustic properties. The images produced by such algorithms can contain significant distortions and artifacts when the object's acoustic properties are spatially variant. In this work, we establish an image reconstruction formula for PAT applications in which a planar detection surface is employed and the to-be-imaged optical absorber is embedded in a known planar layered acoustic medium. The reconstruction formula is exact in a mathematical sense and accounts for multiple acoustic reflections between the layers of the medium. Computer-simulation studies are conducted to demonstrate and investigate the proposed method. PMID:21643397

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

    SciTech Connect

    Ken L. Telschow

    2004-07-01

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

  6. Reproducibility of dynamically represented acoustic lung images from healthy individuals

    PubMed Central

    Maher, T M; Gat, M; Allen, D; Devaraj, A; Wells, A U; Geddes, D M

    2008-01-01

    Background and aim: Acoustic lung imaging offers a unique method for visualising the lung. This study was designed to demonstrate reproducibility of acoustic lung images recorded from healthy individuals at different time points and to assess intra- and inter-rater agreement in the assessment of dynamically represented acoustic lung images. Methods: Recordings from 29 healthy volunteers were made on three separate occasions using vibration response imaging. Reproducibility was measured using quantitative, computerised assessment of vibration energy. Dynamically represented acoustic lung images were scored by six blinded raters. Results: Quantitative measurement of acoustic recordings was highly reproducible with an intraclass correlation score of 0.86 (very good agreement). Intraclass correlations for inter-rater agreement and reproducibility were 0.61 (good agreement) and 0.86 (very good agreement), respectively. There was no significant difference found between the six raters at any time point. Raters ranged from 88% to 95% in their ability to identically evaluate the different features of the same image presented to them blinded on two separate occasions. Conclusion: Acoustic lung imaging is reproducible in healthy individuals. Graphic representation of lung images can be interpreted with a high degree of accuracy by the same and by different reviewers. PMID:18024534

  7. Restricted aperture acoustic microscope lens for Rayleigh wave imaging

    Microsoft Academic Search

    D. A. Davids; P. Y. Wu; D. Chizhik

    1989-01-01

    The performance of an acoustic microscope lens is reported that permits both Rayleigh wave velocity measurement of anisotropic media as well as raster-scanned imaging. The lens surface is spherical and uses a circular p-wave transducer; however, an acoustic absorbing layer is applied to the spherical surface in order to limit the angular range over which Rayleigh waves are launched. When

  8. Acoustic radiation force-based elasticity imaging methods

    PubMed Central

    Palmeri, Mark L.; Nightingale, Kathryn R.

    2011-01-01

    Conventional diagnostic ultrasound images portray differences in the acoustic properties of soft tissues, whereas ultrasound-based elasticity images portray differences in the elastic properties of soft tissues (i.e. stiffness, viscosity). The benefit of elasticity imaging lies in the fact that many soft tissues can share similar ultrasonic echogenicities, but may have different mechanical properties that can be used to clearly visualize normal anatomy and delineate pathological lesions. Acoustic radiation force-based elasticity imaging methods use acoustic radiation force to transiently deform soft tissues, and the dynamic displacement response of those tissues is measured ultrasonically and is used to estimate the tissue's mechanical properties. Both qualitative images and quantitative elasticity metrics can be reconstructed from these measured data, providing complimentary information to both diagnose and longitudinally monitor disease progression. Recently, acoustic radiation force-based elasticity imaging techniques have moved from the laboratory to the clinical setting, where clinicians are beginning to characterize tissue stiffness as a diagnostic metric, and commercial implementations of radiation force-based ultrasonic elasticity imaging are beginning to appear on the commercial market. This article provides an overview of acoustic radiation force-based elasticity imaging, including a review of the relevant soft tissue material properties, a review of radiation force-based methods that have been proposed for elasticity imaging, and a discussion of current research and commercial realizations of radiation force based-elasticity imaging technologies. PMID:22419986

  9. An experimental acoustic cloak for generating virtual images

    NASA Astrophysics Data System (ADS)

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

    2013-01-01

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

  10. Fracture analysis in borehole acoustic images using mathematical morphology

    NASA Astrophysics Data System (ADS)

    Xavier, Aldenize; Guerra, Carlos Eduardo; Andrade, André

    2015-06-01

    Fracture analysis is a geological task that treats so-called fracture attributes (location, direction (strike), slope (dip), and aperture) of the fractures that cross the borehole. It can be performed by direct measures on drill cores or interpreted on acoustic or electromagnetic images of the borehole wall. This activity has gained more importance in Brazil with the recent exploration of carbonate reservoirs of the Brazilian pre-salt. The acoustic imaging logging tool creates two images, the amplitude and the travel time. Only the amplitude image, which reflects the acoustic impedance of the borehole wall, is used to perform the fracture analysis. However, some misinterpretations may occur due to the qualitative nature of this interpretation being very dependent on the geologist’s expertise. Thus, we present a method of performing automation of the fracture analysis using acoustic amplitude images. This article is divided into two parts. In the first part, we present a mathematical model for the acoustic amplitude images along the borehole trajectory crossed by fractures. This model involves all fracture attributes in the generation of the images and is used to validate the results of fracture analysis. The second part presents the method for automatic fracture analysis. This method is composed of two stages. The first one performs fracture identification using an algorithm based on the mathematical morphology, which acts as an edge-detection tool that delimits the fracture region in the acoustic amplitude images. In the second stage, we apply an interpolating polynomial over the image region previously identified as fracture to extract the fracture attributes. The evaluation of this methodology is performed with synthetic images generated by the presented model that supports the results of the automatic fracture analysis performed using real acoustic amplitude images.

  11. Audio classification using acoustic images for retrieval from multimedia databases

    Microsoft Academic Search

    Ioannis Paraskevas; Edward Chilton

    2003-01-01

    With the increasing use of audio-visual databases, the need for automatic content-based classification has grown in importance. In this paper, a novel method for the automatic recognition of acoustic utterances is presented using acoustic images as the basis for the feature extraction. This method effectively employs the spectrogram, the Wigner-Ville distribution and co-occurrence matrices. The images are then compressed, using

  12. Adjustable Acoustic Knife Edge for Anisotropic and Dark-Field Acoustic Imaging

    NASA Astrophysics Data System (ADS)

    Kolosov, Oleg; Yamanaka, Kazushi

    1994-01-01

    A new effective method for acoustic anisotropy and dark-field imaging in reflection ultrasonic focusing devices is proposed. Part of the spherical acoustic wave propagating to and coming from the object is stopped by an ultrasonically opaque acoustic knife edge (AKE) set at the aperture plane of the focusing lens or transducer. This AKE provides the focusing device with directional sensitivity and the capacity for dark-field imaging. Sensitivity of the AKE system to the elastic anisotropy of the leaky surface acoustic wave (LSAW) velocity was demonstrated using an X-cut LiNbO3 crystal. Dark-field imaging of cracks in Si3N4 ceramics and the structure of carbon fiber-reinforced plastic (FRP) was performed. This method can be easily applied to commercially available focusing systems and allows optimization of the setup for the microscopic study of various objects.

  13. CO2 leak detection through acoustic sensing and infrared imaging

    NASA Astrophysics Data System (ADS)

    Cui, Xiwang; Yan, Yong; Ma, Lin; Ma, Yifan; Han, Xiaojuan

    2014-04-01

    When CO2 leakage occurs from a high pressure enclosure, the CO2 jet formed can produce fierce turbulent flow generating acoustic emission with possible phase change, depending on the pressure of the enclosure, and a significant temperature drop in the region close to the releasing point. Acoustic Emission (AE) and infrared imaging technologiesare promising methods for on-line monitoring of such accidental leakage. In this paper, leakage experiments were carried out with a CO2 container under well controlled conditions in a laboratory. Acoustic signals and temperature distribution at the leakage area were acquired using an acoustic sensor and an infraredthermalimaging camera. The acoustic signal was analyzed in both time and frequency domains. The characteristics of the signal frequencies areidentified, and their suitability for leakage detectionis investigated. The location of the leakage can be identified by seeking the lowest temperature area or point in the infrared image.

  14. Acoustic Transmission and Image Contrast of Tilted Plate Specimens in Transmission Acoustic Microscopy

    Microsoft Academic Search

    JUNG K. WANG; CHEN S. TSAI

    1985-01-01

    Abstmct-The results of a study on acoustic transmission and image contrast of a tilted plate specimen in transmission scanning acoustic microscopy (SAhI) are presented. Both the transmission angular spectra and the angular contrasts, as a function of the axial location and the tilt angle of the specimen, are analyzed using the Fourier decomposition technique. The angle-dependent transmission coefficient of a

  15. Acoustic imaging in a water filled metallic pipe

    SciTech Connect

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

    1984-04-01

    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.

  16. Acoustic imaging in a water filled metallic pipe

    SciTech Connect

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

    1985-02-01

    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.

  17. NONLINEAR ACOUSTIC IMAGING OF STRUCTURAL DAMAGES IN LAMINATED COMPOSITES

    E-print Network

    Boyer, Edmond

    are performed on a carbon fiber/epoxy laminated composite plate with barely visible impact damageNONLINEAR ACOUSTIC IMAGING OF STRUCTURAL DAMAGES IN LAMINATED COMPOSITES L. Pieczonka1 , A. Klepka1 for imaging of structural damage in a laminated composite plate. The techniques that have been considered

  18. Acoustic Radiation Force Impulse (ARFI) Imaging: a Review

    PubMed Central

    Nightingale, Kathy

    2012-01-01

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

  19. Respiratory acoustic thoracic imaging (RATHI): Assessing deterministic interpolation techniques

    Microsoft Academic Search

    S. Charleston-Villalobos; S. Cortés-Rubiano; R. González-Camerena; G. Chi-Lem; T. Aljama-Corrales

    2004-01-01

    As respiratory sounds contain mechanical and clinical pulmonary information, technical efforts have been devoted during the\\u000a past decades to analysing, processing and visualising them. The aim of this work was to evaluate deterministic interpolating\\u000a functions to generate surface respiratory acoustic thoracic images (RATHIs), based on multiple acoustic sensors. Lung sounds\\u000a were acquired from healthy subjects through a 55 microphone array

  20. Acoustic Daylight: Passive acoustic imaging using ambient noise

    Microsoft Academic Search

    Chad Lawrence Epifanio

    1997-01-01

    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

  1. Performance Evaluation of a Biometric System Based on Acoustic Images

    PubMed Central

    Izquierdo-Fuente, Alberto; del Val, Lara; Jiménez, María I.; Villacorta, Juan J.

    2011-01-01

    An acoustic electronic scanning array for acquiring images from a person using a biometric application is developed. Based on pulse-echo techniques, multifrequency acoustic images are obtained for a set of positions of a person (front, front with arms outstretched, back and side). Two Uniform Linear Arrays (ULA) with 15 ?/2-equispaced sensors have been employed, using different spatial apertures in order to reduce sidelobe levels. Working frequencies have been designed on the basis of the main lobe width, the grating lobe levels and the frequency responses of people and sensors. For a case-study with 10 people, the acoustic profiles, formed by all images acquired, are evaluated and compared in a mean square error sense. Finally, system performance, using False Match Rate (FMR)/False Non-Match Rate (FNMR) parameters and the Receiver Operating Characteristic (ROC) curve, is evaluated. On the basis of the obtained results, this system could be used for biometric applications. PMID:22163708

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

    SciTech Connect

    Ken Telschow; John D. Larson III

    2006-10-01

    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.

  3. Acoustic Angiography: A New Imaging Modality for Assessing Microvasculature Architecture

    PubMed Central

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

    2013-01-01

    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

  4. Image reconstruction in optoacoustic tomography for dispersive acoustic media.

    PubMed

    La Rivière, Patrick J; Zhang, Jin; Anastasio, Mark A

    2006-03-15

    Conventional image reconstruction methods for optoacoustic tomography (OAT) assume an idealized, non-dispersive acoustic medium. However, the linear attenuation coefficient and the phase velocity of acoustic waves propagating in soft tissue depend on temporal frequency and satisfy a known dispersion law. These frequency-dependent effects are incorporated into an optoacoustic wave equation, and a corresponding reconstruction method for OAT is developed. The improvement in image fidelity that can be achieved over conventional reconstruction methods is demonstrated by use of computer-simulation studies. PMID:16544622

  5. Acoustic-optical imaging without immersion

    NASA Technical Reports Server (NTRS)

    Liu, H.

    1979-01-01

    System using membraneous end wall of Bragg cell to separate test specimen from acoustic transmission medium, operates in real time and uses readily available optical components. System can be easily set up and maintained by people with little or no training in holography.

  6. Acoustic-resolution photoacoustic imaging system with simple fiber illumination

    NASA Astrophysics Data System (ADS)

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

    2013-03-01

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

  7. ACOUSTIC RANGE IMAGE SEGMENTATION BY EFFECTIVE MEAN SHIFT U. Castellani, M. Cristani, V. Murino

    E-print Network

    Castellani, Umberto

    to the segmentation of acoustical range images, pro- viding a segmentation approach in which whatever parameter tuningACOUSTIC RANGE IMAGE SEGMENTATION BY EFFECTIVE MEAN SHIFT U. Castellani, M. Cristani, V. Murino fashion. Index Terms-- Acoustic signal processing, Image seg- mentation, Clustering methods 1

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

    E-print Network

    Intrator, Nathan

    systems are widely used to obtain images of seabed or other underwater objects. An acoustic cameraMosaicing 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

  9. Imaging of Focal Contacts of Chicken Heart Muscle Cells by High-Frequency Acoustic Microscopy

    Microsoft Academic Search

    Eike C. Weiss; Robert M. Lemor; Götz Pilarczyk; Pavlos Anastasiadis; Pavel V. Zinin

    2007-01-01

    A study of the adhesion of embryonic chicken heart muscle cells was conducted with a newly developed time-resolved acoustic microscope, which operates in the GHz-frequency range. The interpretation of the acoustical images of the heart muscle cells was done in combination with the fluorescence optical microscopy. A comparison between the acoustical images of chicken heart muscle cells and optical images

  10. EFFICIENT DETECTION OF LANDMINES FROM ACOUSTIC IMAGES

    Microsoft Academic Search

    H. Kasban; Osama Zahran; M. El-Kordy; Sayed M. S. Elaraby; S. El-Rabie; Fathi El-Sayed Abd El-Samie

    2009-01-01

    Abstract—The Laser Doppler Vibrometer (LDV)-based Acoustic to Seismic (A\\/S) landmine detection system is one of the reliable and powerful landmine detection systems. The interpretation of the LDV- based A\\/S data is performed off-line, manually, depending heavily on the skills, experience, alertness and consistency of a trained operator. This takes a long time. The manually obtained results suffer from errors, particularly

  11. Acoustic imaging of underground storage tank wastes

    SciTech Connect

    Mech, S.J.

    1995-09-01

    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.

  12. A fast transform for acoustic imaging with separable arrays

    Microsoft Academic Search

    Flávio P. Ribeiro; Vitor H. Nascimento

    2011-01-01

    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

  13. Automated acoustic seabed classification from swath images

    Microsoft Academic Search

    J. M. Preston; W. T. Collins

    Dividing multibeam and sidescan seabed images into regions that have similar sediments is often done by expert interpretation. Automated classification systems are not widely used at present. This paper describes techniques that lead to useful and practical automated classifications of swath images, and includes several examples. Image amplitudes and texture are exploited for manual and automated classification. Sediment type affects

  14. Acoustic imaging for diagnostics of chemically reacting systems

    NASA Technical Reports Server (NTRS)

    Ramohalli, K.; Seshan, P.

    1983-01-01

    The concept of local diagnostics, in chemically reacting systems, with acoustic imaging is developed. The elements of acoustic imaging through ellipsoidal mirrors are theoretically discussed. In a general plan of the experimental program, the first system is chosen in these studies to be a simple open jet, non premixed turbulent flame. Methane is the fuel and enriched air is the oxidizer. This simple chemically reacting flow system is established at a Reynolds number (based on cold viscosity) of 50,000. A 1.5 m diameter high resolution acoustic mirror with an f-number of 0.75 is used to map the acoustic source zone along the axis of the flame. The results are presented as acoustic power spectra at various distances from the nozzle exit. It is seen that most of the reaction intensity is localized in a zone within 8 diameters from the exit. The bulk reactions (possibly around the periphery of the larger eddies) are evenly distributed along the length of the flame. Possibilities are seen for locally diagnosing single zones in a multiple cluster of reaction zones that occur frequently in practice. A brief outline is given of the future of this work which will be to apply this technique to chemically reacting flows not limited to combustion.

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

    PubMed Central

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

    2013-01-01

    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

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

    E-print Network

    Paris-Sud XI, Université de

    the ultrasound source and the object, an acoustic lens focusing. Such diopter is achieved using two materialsHigh-frequency acoustic imaging with focused transducer for rapid micro echography of interfaces of the Acoustics 2012 Nantes Conference 23-27 April 2012, Nantes, France 3343 #12;The high frequency micro acoustic

  17. Opti-Acoustic Stereo Imaging, System Calibration and 3-D Reconstruction

    Microsoft Academic Search

    Shahriar Negahdaripour; Hicham Sekkati; Hamed Pirsiavash

    2007-01-01

    Utilization of an acoustic camera for range measure- ments is a key advantage for 3-D shape recovery of under- water targets by opti-acoustic stereo imaging, where the as- sociated epipolar geometry of optical and acoustic image correspondences can be described in terms of conic sec- tions. In this paper, we propose methods for system cali- bration and 3-D scene reconstruction

  18. Opti-Acoustic Stereo Imaging: On System Calibration and 3-D Target Reconstruction

    Microsoft Academic Search

    Shahriar Negahdaripour; Hicham Sekkati; Hamed Pirsiavash

    2009-01-01

    Utilization of an acoustic camera for range measurements is a key advantage for 3-D shape recovery of underwater targets by opti-acoustic stereo imaging, where the associated epipolar geometry of optical and acoustic image correspondences can be described in terms of conic sections. In this paper, we propose methods for system calibration and 3-D scene reconstruction by maximum likelihood estimation from

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

    E-print Network

    Reif, Rafael

    IEEE TRANSACTIONS ON IMAGE PROCESSING, VOL. 18, NO. 6, JUNE 2009 1203 Opti-Acoustic Stereo Imaging the performance in compar- ison with the processing of images from each sensor, alone. This multisensor fusion shape recovery of underwater targets by opti-acoustic stereo imaging, where the associated epipolar

  20. Segmentation of images from an acoustic lens sonar

    Microsoft Academic Search

    Warren L. J. Fox; Julia B. Hsieh; Christina Polwarth

    2004-01-01

    The Dual-Frequency Identification Sonar (DIDSON) is a high frequency (1.0 or 1.8 MHz), high resolution underwater imaging device. An important stage in the classification and identification of objects resting on the seabed is the estimation of object height and width. These estimates can be made based on the acoustic shadow cast by such objects when illuminated by high frequency active

  1. Ultra high frequency imaging acoustic microscope

    DOEpatents

    Deason, Vance A.; Telschow, Kenneth L.

    2006-05-23

    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.

  2. Investigation of an acoustical holography system for real-time imaging

    Microsoft Academic Search

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

    1998-01-01

    A new prototype imaging system based on ultrasound transmission through the object of interest -- acoustical holography -- was developed which incorporates significant improvements in acoustical and optical design. This system is being evaluated for potential clinical application in the musculoskeletal system, interventional radiology, pediatrics, monitoring of tumor ablation, vascular imaging and breast imaging. System limiting resolution was estimated using

  3. Edge Diffraction Phenomena in High-Resolution Acoustical Imaging

    NASA Astrophysics Data System (ADS)

    Ding, Jin Wen; Levin, Vadim Moiseevich; Petronyuk, Yulia Stepanovna

    In flat and homogeneous areas reflected radiation is the sole reason of output signal formation. Distinctions in reflectivity, interference of directly reflected radiation and leaky surface waves cause variations of the output signal values and, finally, contrast in acoustic images. But quality of images is determined also by definition (sharpness) of linear and point elements- phase boundaries, object contour and inclusion borders, edges and so on. At all these positions the secondary radiation includes, besides the reflected part, the diffracted waves also. The work is aimed at analysis and experimental investigation of imaging features caused by contribution of diffracted waves. It has been shown that, while defocusing the signals are separated in time. The diffracted wave is received within a rather wide range of lens positions; its arrival time varies when shifting the probe beam axis about the edge position. Elements originating from edge diffracted waves are indispensable details of all acoustic images - echo patterns, B- and C-scans. It has been shown edge diffracted waves are the main cause of line blurring in C-scans under defocusing.

  4. Airframe noise measurements by acoustic imaging

    NASA Technical Reports Server (NTRS)

    Kendall, J. M.

    1977-01-01

    Studies of the noise produced by flow past wind tunnel models are presented. The central objective of these is to find the specific locations within a flow which are noisy, and to identify the fluid dynamic processes responsible, with the expectation that noise reduction principles will be discovered. The models tested are mostly simple shapes which result in types of flow that are similar to those occurring on, for example, aircraft landing gear and wheel cavities. A model landing gear and a flap were also tested. Turbulence has been intentionally induced as appropriate in order to simulate full-scale effects more closely. The principal technique involves use of a highly directional microphone system which is scanned about the flow field to be analyzed. The data so acquired are presented as a pictorial image of the noise source distribution. An important finding is that the noise production is highly variable within a flow field and that sources can be attributed to various fluid dynamic features of the flow. Flow separation was not noisy, but separation closure usually was.

  5. Acoustic Radiation Force Impulse Imaging of Human Prostates ex vivo

    PubMed Central

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

    2010-01-01

    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

  6. Synthetic aperture imaging by scanning acoustic microscopy with vector contrast

    PubMed

    Ndop; Kim; Grill; Pluta

    2000-03-01

    Based on phase sensitive scanning acoustic microscopy (PSAM), a novel scheme suitable for volume imaging has been developed. The method employs synthetic aperture insonification combined with synthetic aperture imaging. Excitation and detection are performed by planar scanning of two focusing transducer and vector (phase and amplitude) detectors for the ultrasonic wave packages observed in transmission. Examples for applications of the scheme, including technically relevant simplifications based on reduced dimensions of the scan ranges, are presented. Detection schemes already applied for non-destructive testing (NDT) and non-destructive evaluation (NDE) of the mechanical properties of functionally graded materials are an example for the application of the generalised approach presented here with reduced dimensions of the scan. The technique is suitable for NDT and NDE imaging respectively with three-dimensional resolution. PMID:10829651

  7. A Dual Communication and Imaging Underwater Acoustic System

    NASA Astrophysics Data System (ADS)

    Fu, Tricia C.

    A dual communication and imaging underwater acoustic system is proposed and developed throughout this dissertation. Due to the wide variation in underwater channel characteristics, the research here focuses more on robustness to multipath in the shallow underwater acoustic environment, rather than high bit-rate applications and signaling schemes. Lower bit-rate (in the hundreds of bits per second (bps) to low kbps), applications such as the transfer of ecological telemetry data, e.g. conductivity or temperature data, are the primary focus of this dissertation. The parallels between direct sequence spread spectrum in digital communication and pulse-echo with pulse compression in imaging, and channel estimation in communication and range profile estimation in imaging are drawn, leading to a unified communications and imaging platform. A digital communication algorithm for channel order and channel coefficient estimation and symbol demodulation using Matching Pursuit (MP) with Generalized Multiple Hypothesis Testing (GMHT) is implemented in programmable DSP in real time with field experiment results in varying underwater environments for the single receiver (Rx), single transmitter (Tx) case. The custom and off-the-shelf hardware used in the single receiver, single transmitter set of experiments are detailed as well. This work is then extended to the single-input multiple-output (SIMO) case, and then to the full multiple-input multiple-output (MIMO) case. The results of channel estimation are used for simple range profile imaging reconstructions. Successful simulated and experimental results for both transducer array configurations are presented and analyzed. Non-real-time symbol demodulation and channel estimation is performed using experimental data from a scaled testing environment. New hardware based on cost-effective fish-finder transducers for a 6 Rx--1 Tx and 6 Rx--4 Tx transducer array is detailed. Lastly, in an application that is neither communication nor imaging, a generalized successive interference cancellation (GSIC)-based localization algorithm is used to localize discrete scatterers which are assumed to be more prominent than the surrounding clutter. Theory and experimental results are provided to support the feasability of GSIC localization for use with a dual communication and imaging underwater acoustic system.

  8. A magnetic resonance imaging-based articulatory and acoustic study of "retroflex" and "bunched" American English /r/.

    PubMed

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

    2008-06-01

    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

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

    PubMed Central

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

    2008-01-01

    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

  10. Acoustic imaging of hydrothermal plumes. East Pacific rise, 21°N, 109°W

    Microsoft Academic Search

    P. A. Rona; D. R. Palmer; C. Jones; D. A. Chayes; M. Czarnecki; E. W. Carey; J. C. Guerrero

    1991-01-01

    We report the first observations based on acoustic imaging of large-scale structure and time variability of buoyant plumes emanating from black smoker-type seafloor hot springs. Three-dimensional plume reconstructions were made from a digital data set of acoustic backscattering information recorded on a prototype submersible-mounted sonar system. The acoustic images of two adjacent black smokers depict volume and show zones of

  11. Acoustic imaging of hydrothermal plumes, East Pacific Rise, 21°N, 109°W

    Microsoft Academic Search

    P. A. Rona; D. R. Palmer; C. Jones; D. A. Chayes; M. Czarnecki; E. W. Carey; J. C. Guerrero

    1991-01-01

    We report the first observations based on acoustic imaging of large-scale structure and time variability of buoyant plumes emanating from black smoker-type seafloor hot springs. Three-dimensional plume reconstructions were made from a digital data set of acoustic backscattering information recorded on a prototype submersible-mounted sonar system. The acoustic images of two adjacent black smokers depict volume and show zones of

  12. Acoustic images of mud volcanoes in the Sorokin Trough, Black Sea

    Microsoft Academic Search

    S. Krastel; V. Spiess; P. Ivanov; M. Shashkin; W. Weinrebe; G. Bohrmann

    2003-01-01

    The Sorokin Trough (Black Sea) is characterized by diapiric structures and compressional tectonics that facilitate fluid migration to the seafloor. Abundant mud volcanoes and near surface gas hydrate occurrences were identified in this area. We present acoustic images of the mud volcanoes in the Sorokin Trough, which we collected recently with a variety of different seismic and acoustic imaging systems.

  13. ACOUSTIC RANGE IMAGE SEGMENTATION BY EFFECTIVE MEAN SHIFT U. Castellani, M. Cristani, V. Murino

    E-print Network

    Cristani, Marco

    to the segmentation of acoustical range images, pro- viding a segmentation approach in which whatever parameter tuningACOUSTIC RANGE IMAGE SEGMENTATION BY EFFECTIVE MEAN SHIFT U. Castellani, M. Cristani, V. Murino and several surveys, reporting interesting approaches for different data representa- tions such as unorganized

  14. Long range acoustic imaging of the continental shelf environment: the Acoustic Clutter Reconnaissance Experiment 2001.

    PubMed

    Ratilal, Purnima; Lai, Yisan; Symonds, Deanelle T; Ruhlmann, Lilimar A; Preston, John R; Scheer, Edward K; Garr, Michael T; Holland, Charles W; Goff, John A; Makris, Nicholas C

    2005-04-01

    An active sonar system is used to image wide areas of the continental shelf environment by long-range echo sounding at low frequency. The bistatic system, deployed in the STRATAFORM area south of Long Island in April-May of 2001, imaged a large number of prominent clutter events over ranges spanning tens of kilometers in near real time. Roughly 3000 waveforms were transmitted into the water column. Wide-area acoustic images of the ocean environment were generated in near real time for each transmission. Between roughly 10 to more than 100 discrete and localized scatterers were registered for each image. This amounts to a total of at least 30000 scattering events that could be confused with those from submerged vehicles over the period of the experiment. Bathymetric relief in the STRATAFORM area is extremely benign, with slopes typically less than 0.5 degrees according to high resolution (30 m sampled) bathymetric data. Most of the clutter occurs in regions where the bathymetry is locally level and does not coregister with seafloor features. No statistically significant difference is found in the frequency of occurrence per unit area of repeatable clutter inside versus outside of areas occupied by subsurface river channels. PMID:15898642

  15. Development of an Acoustic Lens for an Imaging Sonar for Autonomous Underwater Vehicle ``Urashima'' and Experimentation in a Water Tank

    Microsoft Academic Search

    Satoshi Tsukioka; Taro Aoki; Hiroshi Ochi; Takuya Shimura; Takao Sawa; Toshiaki Nakamura; Tetsuo Anada; Ieharu Kaihou; Hiroaki Noda

    2002-01-01

    Underwater imaging sonar has been developed for obstacle avoidance and navigation of the autonomous underwater vehicle (AUV) ``URASHIMA''. The acoustic image, the distance and the azimuth of the target are obtained using an acoustic lens. Tone burst acoustic waves are transmitted and scattered at the target, and a direct image of the target can be created on a two-dimensional receiving

  16. Standing tree decay detection by using acoustic tomography images

    NASA Astrophysics Data System (ADS)

    Espinosa, Luis F.; Arciniegas, Andres F.; Prieto, Flavio A.; Cortes, Yolima; Brancheriau, Loïc.

    2015-04-01

    The acoustic tomographic technique is used in the diagnosis process of standing trees. This paper presents a segmentation methodology to separate defective regions in cross-section tomographic images obtained with Arbotom® device. A set of experiments was proposed using two trunk samples obtained from a eucalyptus tree, simulating defects by drilling holes with known geometry, size and position and using different number of sensors. Also, tomographic images from trees presenting real defects were studied, by testing two different species with significant internal decay. Tomographic images and photographs from the trunk cross-section were processed to align the propagation velocity data with a corresponding region, healthy or defective. The segmentation was performed by finding a velocity threshold value to separate the defective region; a logistic regression model was fitted to obtain the value that maximizes a performance criterion, being selected the geometric mean. Accuracy segmentation values increased as the number of sensors augmented; also the position influenced the result, obtaining improved results in the case of centric defects.

  17. Synchronization of Infrared Imaging with Acoustic Emission for Depth Measurement of Discrete Failure Events in Composites

    Microsoft Academic Search

    B. Knight; H. I. Ringermacher; Jian Li; Y. A. Plotnikov; Gulperi Aksel; D. R. Howard; J. L. Thompson

    2007-01-01

    Infrared (IR) imaging together with acoustic emission (AE) sensing are employed to follow the progression to failure of graphite epoxy test panels under dynamic loading. Acoustic emission generated by fiber breaks and matrix cracks define the ``zero'' time for surface observation by an IR camera of the deep heat source from that event. The AE clock and IR clock must

  18. High-speed varifocal imaging with a tunable acoustic gradient index of refraction lens

    E-print Network

    Arnold, Craig B.

    High-speed varifocal imaging with a tunable acoustic gradient index of refraction lens Alexandre by the speed at which focal length can be changed. Here we demonstrate the use of a tunable acoustic gradient (TAG) index of refraction lens as a fast varifocal element. The optical power of the TAG lens varies

  19. An exact wavefield modelling method for data processing, imaging and interferometry applications in scattering acoustic media

    E-print Network

    of new theories and algo- rithms. We present a simple, exact and fast acoustic waveform modelling scheme, a variety of wavefield modelling techniques are currently available in both the acoustic and elastic domainAn exact wavefield modelling method for data processing, imaging and interferometry applications

  20. Adaptive focusing of transcranial therapeutic ultrasound using MR Acoustic Radiation Force Imaging in a clinical environment

    Microsoft Academic Search

    L. Marsac; B. Larrat; M. Pernot; B. Robert; M. Fink; J-F Aubry; M Tanter

    2010-01-01

    Background: In order to focus ultrasound beams through aberrating layers such as fat or bones, adaptive focusing techniques have been proposed to improve the focusing, mostly based on the backscattered echoes. We recently proposed an energy-based technique with the sole requirement being knowledge of the acoustic intensity at the desired focus. Here, Magnetic Resonance-Acoustic Radiation Force Imaging (MR- ARFI) is

  1. Full-field imaging of Gigahertz film bulk acoustic resonator motion.

    PubMed

    Telschow, Ken L; Deason, Vance A; Cottle, David L; Larson, John D

    2003-10-01

    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 x 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. PMID:14609067

  2. Full-Field Imaging of GHz Film Bulk Acoustic Resonator Motion

    SciTech Connect

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

    2003-10-01

    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.

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

    E-print Network

    deHoop, Maarten V.

    2006-03-01

    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 ...

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

    E-print Network

    Lu, Rongrong

    2008-01-01

    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 ...

  5. Negative refraction induced acoustic concentrator and the effects of scattering cancellation, imaging, and mirage

    NASA Astrophysics Data System (ADS)

    Wei, Qi; Cheng, Ying; Liu, Xiao-jun

    2012-07-01

    We present a three-dimensional acoustic concentrator capable of significantly enhancing the sound intensity in the compressive region with scattering cancellation, imaging, and mirage effects. The concentrator shell is built by isotropic gradient negative-index materials, which together with an exterior host medium slab constructs a pair of complementary media. The enhancement factor, which can approach infinity by tuning the geometric parameters, is always much higher than that of a traditional concentrator made by positive-index materials with the same size. The acoustic scattering theory is applied to derive the pressure field distribution of the concentrator, which is consistent with the numerical full-wave simulations. The inherent acoustic impedance match at the interfaces of the shell as well as the inverse processes of “negative refraction—progressive curvature—negative refraction” for arbitrary sound rays can exactly cancel the scattering of the concentrator. In addition, the concentrator shell can also function as an acoustic spherical magnifying superlens, which produces a perfect image with the same shape, with bigger geometric and acoustic parameters located at a shifted position. Then some acoustic mirages are observed whereby the waves radiated from (scattered by) an object located in the center region may seem to be radiated from (scattered by) its image. Based on the mirage effect, we further propose an intriguing acoustic transformer which can transform the sound scattering pattern of one object into another object at will with arbitrary geometric, acoustic, and location parameters.

  6. Negative refraction imaging of acoustic metamaterial lens in the supersonic range

    NASA Astrophysics Data System (ADS)

    Han, Jianning; Wen, Tingdun; Yang, Peng; Zhang, Lu

    2014-05-01

    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.

  7. Negative refraction imaging of acoustic metamaterial lens in the supersonic range

    SciTech Connect

    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

    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.

  8. ACOUSTICAL IMAGING AND MECHANICAL PROPERTIES OF SOFT ROCK AND MARINE SEDIMENTS

    SciTech Connect

    Thurman E. Scott, Jr.; Younane Abousleiman

    2004-04-01

    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.

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

    USGS Publications Warehouse

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

    2004-01-01

    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.

  10. Analysis of Particle Image Velocimetry (PIV) Data for Acoustic Velocity Measurements

    NASA Technical Reports Server (NTRS)

    Blackshire, James L.

    1997-01-01

    Acoustic velocity measurements were taken using Particle Image Velocimetry (PIV) in a Normal Incidence Tube configuration at various frequency, phase, and amplitude levels. This report presents the results of the PIV analysis and data reduction portions of the test and details the processing that was done. Estimates of lower measurement sensitivity levels were determined based on PIV image quality, correlation, and noise level parameters used in the test. Comparison of measurements with linear acoustic theory are presented. The onset of nonlinear, harmonic frequency acoustic levels were also studied for various decibel and frequency levels ranging from 90 to 132 dB and 500 to 3000 Hz, respectively.

  11. Acoustic lens characterization for ultrasound and photoacoustic C-scan imaging modalities

    Microsoft Academic Search

    Navalgund A. Rao; Di Lai; Shweta Bhatt; Stephen C. Arnold; Bhargava Chinni; Vikram S. Dogra

    2008-01-01

    From a fundamental perspective, image reconstruction tasks in both ultrasound pulse echo and photoacoustic imaging are identical. We propose a C-scan imaging scheme that is applicable to both modalities where the image reconstruction is achieved through focusing action of an acoustic lens. The theory to characterize the imaging system is presented. Experimental methodology to determine the system point-spread-function is outlined

  12. Acoustic lens characterization for ultrasound and photoacoustic C-scan imaging modalities.

    PubMed

    Rao, Navalgund A; Lai, Di; Bhatt, Shweta; Arnold, Stephen C; Chinni, Bhargava; Dogra, Vikram S

    2008-01-01

    From a fundamental perspective, image reconstruction tasks in both ultrasound pulse echo and photoacoustic imaging are identical. We propose a C-scan imaging scheme that is applicable to both modalities where the image reconstruction is achieved through focusing action of an acoustic lens. The theory to characterize the imaging system is presented. Experimental methodology to determine the system point-spread-function is outlined and demonstrated with preliminary results. PMID:19163129

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

    NASA Technical Reports Server (NTRS)

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

    2006-01-01

    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.

  14. An Acoustic Charge Transport Imager for High Definition Television

    NASA Technical Reports Server (NTRS)

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

    1999-01-01

    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.

  15. Opto-acoustic image fusion technology for diagnostic breast imaging in a feasibility study

    NASA Astrophysics Data System (ADS)

    Zalev, Jason; Clingman, Bryan; Herzog, Don; Miller, Tom; Ulissey, Michael; Stavros, A. T.; Oraevsky, Alexander; Lavin, Philip; Kist, Kenneth; Dornbluth, N. C.; Otto, Pamela

    2015-03-01

    Functional opto-acoustic (OA) imaging was fused with gray-scale ultrasound acquired using a specialized duplex handheld probe. Feasibility Study findings indicated the potential to more accurately characterize breast masses for cancer than conventional diagnostic ultrasound (CDU). The Feasibility Study included OA imagery of 74 breast masses that were collected using the investigational Imagio® breast imaging system. Superior specificity and equal sensitivity to CDU was demonstrated, suggesting that OA fusion imaging may potentially obviate the need for negative biopsies without missing cancers in a certain percentage of breast masses. Preliminary results from a 100 subject Pilot Study are also discussed. A larger Pivotal Study (n=2,097 subjects) is underway to confirm the Feasibility Study and Pilot Study findings.

  16. Acoustic\\/seismic identifications, imaging, and communications in Steel Rattler

    Microsoft Academic Search

    Kevin T. Malone; Loren E. Riblett; Thomas J. Essenmacher

    1997-01-01

    Unattended ground sensors (UGS) utilize data from a variety of sensors (e.g., acoustic, seismic, and imagery) to make a determination about an unknown potential target. The Steel Rattler UGS derives its target identification solution from acoustic and seismic data. The identification solution and optional still imagery of the target are transmitted to the appropriate operating bases via satellite. This paper

  17. ADVANCED MOSAIC TECHNIQUES OF ACOUSTIC VIDEO IMAGES FOR UNDERWATER SURVEILLANCE AND DIAGNOSING DEGRADATION LEVELS OF HARBOR STRUCTURES

    Microsoft Academic Search

    Akira Asada; Hideki Kunishima; Tadashi Igarashi; Tadashi Nagase; Takeya Matsuda

    Using an acoustic video camera DIDSON, we took acoustic video images of a ship's hull and an entire wharf of several hundred meter wide, and then created seamless mosaic images with 0.5cm and 1cm accuracies by correcting the distortion and adjusting the brightness of the video images. This method is effective in detecting suspicious objects around wharfs, ship's hulls and

  18. Picosecond time resolved opto-acoustic imaging with 48 MHz frequency resolution.

    PubMed

    Abbas, A; Guillet, Y; Rampnoux, J-M; Rigail, P; Mottay, E; Audoin, B; Dilhaire, S

    2014-04-01

    A compact femtosecond dual-oscillator pump-probe setup with 48 MHz-repetition rate, relying on asynchronous optical sampling, is presented. The relative timing jitter between both lasers over the whole pump-probe delay range is of the order of or lower than 500 fs. We demonstrate that both a picosecond temporal resolution and a 48 MHz spectral resolution combined with the fast acquisition rate inherent to the asynchronous optical sampling allow performing broadband opto-acoustic imaging with a spectrum covering more than two decades from 300 MHz to 150 GHz. As an illustration, the opto-acoustic response of a supported thin film is investigated, revealing high frequency acoustic echoes close to the epicenter as well as low GHz surface acoustic waves propagating up to 40?m away from the epicenter. Semi-analytical calculations have been carried out and perfectly reproduce the dispersion of the surface acoustic waves experimentally observed. PMID:24718159

  19. Two dimensional photoacoustic imaging based on an acoustic lens and the peak-hold technology.

    PubMed

    Zhang, Hanchao; Tang, Zhilie; He, Yongheng; Guo, Lina

    2007-06-01

    A new method of photoacoustic (PA) imaging based on an acoustic lens and the peak-hold technology is presented in this article. A fast PA imaging system, which consists of an acoustic lens, a 64-element linear transducer array, and a peak detection-and-hold circuit, is developed to obtain the two dimensional (2D) PA images of the experimental samples. By utilizing an acoustic lens, the PA signals generated from the sample are directly imaged on the imaging plane and collected by the 64-element linear transducer array which changes the PA signals into the corresponding electronic signals. Then the electronic signals are converted into a one dimensional image using the peak detection-and-hold circuit. After vertical scanning with a step motor on the imaging plane, the 2D PA image of the sample is achieved successfully. The results show that the images reconstructed in this experiment agree well with the original samples. Compared to other methods, this PA imaging system can acquire the PA images more rapidly without any complex algorithms, and it may provide a more convenient method for future in vivo noninvasive imaging of tissues and clinic diagnosis. PMID:17614630

  20. Computations of acoustically induced phase shifts of optical paths in acousto-photonic imaging

    Microsoft Academic Search

    Florian J. Blonigen; Charles A. DiMarzio

    2005-01-01

    Ultrasound modulated optical signals from scattered laser light in biological tissue have been investigated in order to improve optical imaging quality, a technique we call acousto-photonic imaging (API). Recent experiments using a photorefractive crystal based detection system have shown that there is a large DC-offset to the acoustically modulated AC optical signal, an effect that is second order in the

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

    E-print Network

    Wang, Lihong

    -induced thermoacoustic tomography Xing Jin Department of Biomedical Engineering, Texas A&M University, 3120 TAMU, College: thermoacoustic tomography, transcranial brain imaging, acoustic heterogeneities I. INTRODUCTION Microwave-induced thermoacoustic tomography TAT is a noninvasive and nonionizing imaging modality that can dif- ferentiate

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

    Microsoft Academic Search

    James A. Simmons; Roger A. Stein

    1980-01-01

    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

  3. Image method for efficiently simulatingsmall-room acoustics Jont B. Allen and DavidA. Berkley

    E-print Network

    Allen, Jont

    , atimedomaln mo- del is required. A normal-mode solutionoftheenclosure would require calculation of all.· (Theexactrelationshipbetween the normal-mode solutions and the image solution, for a losslessroom, is discussedin AppendixImage method for efficiently simulatingsmall-room acoustics Jont B. Allen and DavidA. Berkley .4

  4. Reconstructed imaging of acoustic cloak using time-lapse reversal method

    NASA Astrophysics Data System (ADS)

    Zhou, Chen; Cheng, Ying; Xu, Jian-yi; Li, Bo; Liu, Xiao-jun

    2014-08-01

    We proposed and investigated a solution to the inverse acoustic cloak problem, an anti-stealth technology to make cloaks visible, using the time-lapse reversal (TLR) method. The TLR method reconstructs the image of an unknown acoustic cloak by utilizing scattered acoustic waves. Compared to previous anti-stealth methods, the TLR method can determine not only the existence of a cloak but also its exact geometric information like definite shape, size, and position. Here, we present the process for TLR reconstruction based on time reversal invariance. This technology may have potential applications in detecting various types of cloaks with different geometric parameters.

  5. Time-averaged images and quantifications of seafloor hydrothermal plumes from acoustic imaging data: a case study at Grotto Vent, Endeavour Segment Seafloor Observatory

    Microsoft Academic Search

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

    2001-01-01

    Many simple models of plumes predict time-averaged behavior. Although instantaneous measurements of plumes are still useful, time-averaged measurements are more directly comparable. Averages of varying numbers of consecutive acoustic images are quantified and the results compared. The acoustic images of Grotto Vent in the Main Endeavour Vent Field were obtained during the VIP (Vents Imaging Pacific) 2000 cruise using the

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

    NASA Astrophysics Data System (ADS)

    Yegireddi, Satyanarayana; Thomas, Nitheesh

    2014-06-01

    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.

  7. Focusing and subwavelength imaging of surface acoustic waves in a solid-air phononic crystal

    NASA Astrophysics Data System (ADS)

    Veres, Istvan A.; Berer, Thomas; Matsuda, Osamu; Burgholzer, Peter

    2012-09-01

    Focusing and subwavelength imaging of surface acoustic waves (SAWs) through a phononic crystal flat lens are discussed in the presented work. Experimental and numerical wave fields are obtained in the time-domain by an optical technique and by numerical simulations. Spatial distributions of the acoustic field are accessed using a temporal Fourier transform. The revealed focusing of the elastic waves in the first band of the crystal is governed by the concave equifrequency contour of the leaky-Rayleigh wave. The spatial distributions of the experimental and numerical acoustic fields also unfold subwavelength imaging of SAWs. Numerical simulations show that the imaging quality can be improved by embedding the flat lens into a medium with higher wave velocity.

  8. Development of a novel acoustic lens based pulse echo ultrasound imaging system

    NASA Astrophysics Data System (ADS)

    Sinha, Saugata; Rao, Navalgund A.

    2014-03-01

    Acoustic lens based focusing technology where the image reconstruction is achieved through the focusing of an acoustic lens, can potentially replace time consuming and expensive electronic focusing technology for producing high resolution real time ultrasound (US) images. A novel acoustic lens focusing based pulse echo US imaging system is explored here. In the system, a Polyvinylidene fluoride (PVDF) film transducer generates plane wave which is backscattered by the object and focused by a spherical acoustic lens on to a linear array of transducers. To improve the anticipated low signal to noise ratio (SNR) of the received US signal due to the low electromechanical coupling coefficient of the PVDF film, here we explored the possibility of implementing pulse compression technique using linear frequency modulated (FM) signals or chirp signals. Comparisons among the different SNR values obtained with short pulse and after pulse compression with chirp signal show a clear improvement of the SNR for the compressed pulse. The preliminary results show that the SNR achieved for the compressed pulse depends on time bandwidth product of the input chirp and the spectrum of the US transducers. The axial resolution obtained with compressed pulse improved with increasing sweep bandwidth of input chirp signals, whereas the lateral resolution remained almost constant. This work demonstrates the feasibility of using a PVDF film transducer as an US transmitter in an acoustic lens focusing based imaging system and implementing pulse compression technique into the same setup to improve SNR of the received US signal.

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

    DOEpatents

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

    2002-01-01

    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.

  10. The Prototype of Microwave-Induced Thermo-Acoustic Tomography Imaging by Time Reversal Mirror

    Microsoft Academic Search

    G. P. Chen; W. B. Yu; Z. Q. Zhao; Z. P. Nie; Q. H. Liu

    2008-01-01

    Microwave-Induced Thermo-Acoustic Tomography (MITAT) is a promising technique in biologic tissue imaging. It has predominant advantages in both contrast and resolution compared with conventional microwave or ultrasound imaging system for malignant tumors. In this paper, an integrated prototype MITAT system is briefly introduced. And Time Reversal Mirror (TRM) imaging technique based on Pseudo-Spectrum Time Domain (PSTD) is also first time

  11. A surface acoustic wave /SAW/ charge transfer imager

    NASA Technical Reports Server (NTRS)

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

    1981-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-11-01

    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.

  13. Apparatus for real-time acoustic imaging of Rayleigh-Benard convection

    E-print Network

    Kerry Kuehn; Jonathan Polfer; Joanna Furno; Nathan Finke

    2007-07-23

    We have designed and built an apparatus for real-time acoustic imaging of convective flow patterns in optically opaque fluids. This apparatus takes advantage of recent advances in two-dimensional ultrasound transducer array technology; it employs a modified version of a commercially available ultrasound camera, similar to those employed in non-destructive testing of solids. Images of convection patterns are generated by observing the lateral variation of the temperature dependent speed of sound via refraction of acoustic plane waves passing vertically through the fluid layer. The apparatus has been validated by observing convection rolls in both silicone oil and ferrofluid.

  14. An acoustic charge transport imager for high definition television applications

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

    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.

  15. Design and alignment strategies of 4f systems used in the vectorial optical field generator.

    PubMed

    Han, Wei; Cheng, Wen; Zhan, Qiwen

    2015-03-20

    In this paper, the design and alignment strategies of 4f systems used in the vectorial optical field generator are described in detail. Reflection-type 4f systems were adopted due to limited spacing. Alignment patterns are designed and introduced as alignment tools so that the optical property (degree of freedom) controlled by each specific spatial light modulator section can be visualized and alignment of the 4f systems can be performed using the CCD image sharpness as the metric. In particular, blurring due to diffraction effects is minimized when the 4f system is fully aligned. PMID:25968510

  16. INDEX TO VOLUME 169 acoustic images, side-scan, Bent Hill, A:39, 158, 161

    E-print Network

    INDEX TO VOLUME 169 A acoustic images, side-scan, Bent Hill, A:39, 158, 161 actinolite basalts, A photograph, A:100 photomicrograph, A:100 This index covers both the Initial Reports and Scientific Results volume) by "B" followed by the chapter number with a colon (B1:). The index was prepared by Earth Systems

  17. THE ACOUSTIC SHOWERGLASS. II. IMAGING ACTIVE REGION SUBPHOTOSPHERES Charles Lindsey and D. C. Braun

    E-print Network

    Braun, Douglas C.

    THE ACOUSTIC SHOWERGLASS. II. IMAGING ACTIVE REGION SUBPHOTOSPHERES Charles Lindsey and D. C. Braun-correlation seismic holography (Lindsey & Braun 2000; Braun & Lindsey 2000) and time-distance to- mography (Duvall et the underlying solar interior. This study makes frequent reference to two recent papers, Lindsey & Braun (2004

  18. Exploratory and developmental studies leading toward optimization of acoustical holography imaging of cardiovascular system, volume 2

    Microsoft Academic Search

    B. B. Brenden; J. L. Deichman

    1975-01-01

    The objectives of the second phase of this program were to better the imaging capability of the liquid surface acoustical holography system as it relates to the cardiovascular system, to continue the safety study involved with insonification of fertilized fish eggs and to explore the feasibility of using electron spin resonance (ESR) to detect tissue damage from ultrasonic insonification. Lens

  19. Finite Difference Time Domain Analysis of Underwater Acoustic Lens System for Ambient Noise Imaging

    Microsoft Academic Search

    Kazuyoshi Mori; Ayano Miyazaki; Hanako Ogasawara; Tomoki Yokoyama; Toshiaki Nakamura

    2006-01-01

    Much attention has been paid to the new idea of detecting objects using ocean ambient noise. This concept is called ambient noise imaging (ANI). In this study, sound fields focused by an acoustic lens system constructed with a single biconcave lens were analyzed using the finite difference time domain (FDTD) method for realizing an ANI system. The size of the

  20. Simulating the spatially-dependent frequency response of arbitraryshape acoustic detectors for optoacoustic imaging

    Microsoft Academic Search

    Amir Rosenthal; Vasilis Ntziachristos; Daniel Razansky

    2011-01-01

    One of the major challenges of optoacoustic imaging is that it involves relatively weak acoustic signals, which need to be detected with high signal-to-noise ratio (SNR). Because the SNR is generally proportional to the area of the detector's face, large detectors are commonly used. Although the use of such detectors improves the SNR, it may lead to significant signal distortion

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

    E-print Network

    Milchberg, Howard

    Direct imaging of the acoustic waves generated by femtosecond filaments in air J. K. Wahlstrand, N of spatial single- and higher-mode 50 fs, 800 nm pulses in air at 10 Hz and 1 kHz repetition rates. Results in air [9]. They claimed a positive gas density perturba- tion on axis with a microsecond lifetime

  2. 3D snakes for the segmentation of buried mines in 3D acoustic images

    Microsoft Academic Search

    Dominique Attali; J. Chanussot; R. Areste; S. Guyonic

    2005-01-01

    In this paper, we describe some image processing techniques for the analysis of 3D acoustical data. More specifically, the 3D images are segmented using a deformable template (3D snake). This iterative algorithm provides a triangulated surface of the echo generated by buried underwater mines. The segmentation result can then be used for recognition\\/classification of the detected object purpose. The proposed

  3. Automated acoustic seabed classification of multibeam images of Stanton Banks

    Microsoft Academic Search

    Jon Preston

    2009-01-01

    Dividing sidescan images into regions that have similar seabeds is often done by expert interpretation. Automated classification systems are becoming more widely used. This paper describes techniques, based on image amplitudes and texture, that lead to useful and practical automated segmentation of multibeam images. Seabed (or riverbed or lakebed) type affects amplitudes and texture, but so do system operating details

  4. Method and system to synchronize acoustic therapy with ultrasound imaging

    NASA Technical Reports Server (NTRS)

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

    2009-01-01

    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.

  5. Investigation of an acoustical holography system for real-time imaging

    NASA Astrophysics Data System (ADS)

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

    1998-07-01

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

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

    PubMed Central

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

    2014-01-01

    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

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

    PubMed Central

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

    2013-01-01

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

  8. Crosstalk cancellation in virtual acoustic imaging systems for multiple listeners

    NASA Astrophysics Data System (ADS)

    Kim, Y.; Deille, O.; Nelson, P. A.

    2006-10-01

    The perception of a virtual sound source is achieved by ensuring that the sound pressures at the ears of the listener are equivalent to those produced by the source at the virtual position. Theoretically, with only two loudspeakers for a single listener, virtual sources positioned anywhere in space can be presented provided that "crosstalk cancellation" can be achieved. The crosstalk cancellation problem is central to the problem of sound reproduction since an efficient crosstalk canceller gives one complete control over the sound field at a number of target positions. However, all crosstalk cancellation systems implemented so far have in practice produced virtual sources for only a single listener at a time. The design of crosstalk cancellers for multiple listeners involves a detailed study of the relative orientation of both sources and listeners. It is vital in any multiple listener system to first establish the conditioning of the potential geometrical arrangements of transducers and listeners by using simple free field models of the electro-acoustic transfer functions between transducers and ears. This gives an important link between the conditioning of the electro-acoustic transfer function matrix and the inverse filters for crosstalk cancellation. Optimal transducer arrangements for the efficient crosstalk canceller have been identified for the case of two listeners and these are evaluated here with time domain simulations.

  9. Imaging of transient surface acoustic waves by full-field photorefractive interferometry.

    PubMed

    Xiong, Jichuan; Xu, Xiaodong; Glorieux, Christ; Matsuda, Osamu; Cheng, Liping

    2015-05-01

    A stroboscopic full-field imaging technique based on photorefractive interferometry for the visualization of rapidly changing surface displacement fields by using of a standard charge-coupled device (CCD) camera is presented. The photorefractive buildup of the space charge field during and after probe laser pulses is simulated numerically. The resulting anisotropic diffraction upon the refractive index grating and the interference between the polarization-rotated diffracted reference beam and the transmitted signal beam are modeled theoretically. The method is experimentally demonstrated by full-field imaging of the propagation of photoacoustically generated surface acoustic waves with a temporal resolution of nanoseconds. The surface acoustic wave propagation in a 23 mm × 17 mm area on an aluminum plate was visualized with 520 × 696 pixels of the CCD sensor, yielding a spatial resolution of 33 ?m. The short pulse duration (8 ns) of the probe laser yields the capability of imaging SAWs with frequencies up to 60 MHz. PMID:26026514

  10. Imaging of transient surface acoustic waves by full-field photorefractive interferometry

    NASA Astrophysics Data System (ADS)

    Xiong, Jichuan; Xu, Xiaodong; Glorieux, Christ; Matsuda, Osamu; Cheng, Liping

    2015-05-01

    A stroboscopic full-field imaging technique based on photorefractive interferometry for the visualization of rapidly changing surface displacement fields by using of a standard charge-coupled device (CCD) camera is presented. The photorefractive buildup of the space charge field during and after probe laser pulses is simulated numerically. The resulting anisotropic diffraction upon the refractive index grating and the interference between the polarization-rotated diffracted reference beam and the transmitted signal beam are modeled theoretically. The method is experimentally demonstrated by full-field imaging of the propagation of photoacoustically generated surface acoustic waves with a temporal resolution of nanoseconds. The surface acoustic wave propagation in a 23 mm × 17 mm area on an aluminum plate was visualized with 520 × 696 pixels of the CCD sensor, yielding a spatial resolution of 33 ?m. The short pulse duration (8 ns) of the probe laser yields the capability of imaging SAWs with frequencies up to 60 MHz.

  11. Vibro-acoustography: An imaging modality based on ultrasound-stimulated acoustic emission

    PubMed Central

    Fatemi, Mostafa; Greenleaf, James F.

    1999-01-01

    We describe theoretical principles of an imaging modality that uses the acoustic response of an object to a highly localized dynamic radiation force of an ultrasound field. In this method, named ultrasound-stimulated vibro-acoustography (USVA), ultrasound is used to exert a low-frequency (in kHz range) force on the object. In response, a portion of the object vibrates sinusoidally in a pattern determined by its viscoelastic properties. The acoustic emission field resulting from object vibration is detected and used to form an image that represents both the ultrasonic and low-frequency (kHz range) mechanical characteristics of the object. We report the relation between the emitted acoustic field and the incident ultrasonic pressure field in terms of object parameters. Also, we present the point-spread function of the imaging system. The experimental images in this report have a resolution of about 700 ?m, high contrast, and high signal-to-noise ratio. USVA is sensitive enough to detect object motions on the order of nanometers. Possible applications include medical imaging and material evaluation. PMID:10359758

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

    NASA Technical Reports Server (NTRS)

    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

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2001-12-01

    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.

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

    SciTech Connect

    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

    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.

  15. Nanoscale imaging of surface acoustic waves by scanning tunneling microscopy

    NASA Astrophysics Data System (ADS)

    Koch, R.; Yang, Jianshu

    2005-05-01

    The scanning tunneling microscope (STM) has proven to be a powerful technique for probing surface acoustic waves (SAWs) with high spatial resolution. Here we use our ultrahigh-vacuum SAW-STM to investigate a Rayleigh wave excited in LiNbO3 with emphasis laid on the SAW-induced signals at steps that are only a few atomic layers high. Our study reveals that on the length scale of a few nanometer the description of the amplitude and phase contrast by a plain geometrical model fails and a variety of other mechanisms decisively affect the SAW-induced signal. At steps the lateral surface movement due to the SAW may play an important role. For larger step inclination angles also the shape of the STM tip as well as tip-surface interactions become relevant, which may even drive a SAW-induced movement of the tip apex.

  16. An acoustic charge transport imager for high definition television applications

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

    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.

  17. Evaluation of Acoustic Anisotropy to Image Defects in Weld Metal by Ultrasonic Phased Array

    NASA Astrophysics Data System (ADS)

    Shintaku, Yohei; Ohara, Yoshikazu; Yamanaka, Kazushi

    2011-09-01

    An ultrasonic phased array (PA) does not work well in some weld metals owing to the strong acoustic anisotropy. However, the analysis of anisotropy for the compensation of the shift of the defect image in the PA has not been performed. In this study, we compared the results of imaging a slit in a Ni-based weld metal, commercially available as Inconel alloy 600, in an experiment and in simulations using the analytical solution of group velocity or the finite-difference time-domain (FDTD) method. As a result, we succeeded in reproducing the shift and broadening of the defect image obtained in an experiment by the simulations.

  18. Acoustic imaging with time reversal methods: From medicine to NDT

    NASA Astrophysics Data System (ADS)

    Fink, Mathias

    2015-03-01

    This talk will present an overview of the research conducted on ultrasonic time-reversal methods applied to biomedical imaging and to non-destructive testing. We will first describe iterative time-reversal techniques that allow both focusing ultrasonic waves on reflectors in tissues (kidney stones, micro-calcifications, contrast agents) or on flaws in solid materials. We will also show that time-reversal focusing does not need the presence of bright reflectors but it can be achieved only from the speckle noise generated by random distributions of non-resolved scatterers. We will describe the applications of this concept to correct distortions and aberrations in ultrasonic imaging and in NDT. In the second part of the talk we will describe the concept of time-reversal processors to get ultrafast ultrasonic images with typical frame rates of order of 10.000 F/s. It is the field of ultrafast ultrasonic imaging that has plenty medical applications and can be of great interest in NDT. We will describe some applications in the biomedical domain: Quantitative Elasticity imaging of tissues by following shear wave propagation to improve cancer detection and Ultrafast Doppler imaging that allows ultrasonic functional imaging.

  19. Measurement of acoustic velocity in the stack of a thermoacoustic refrigerator using particle image velocimetry

    NASA Astrophysics Data System (ADS)

    Berson, Arganthaël; Michard, Marc; Blanc-Benon, Philippe

    2008-06-01

    Thermoacoustic refrigeration systems generate cooling power from a high-amplitude acoustic standing wave. There has recently been a growing interest in this technology because of its simple and robust architecture and its use of environmentally safe gases. With the prospect of commercialization, it is necessary to enhance the efficiency of thermoacoustic cooling systems and more particularly of some of their components such as the heat exchangers. The characterization of the flow field at the end of the stack plates is a crucial step for the understanding and optimization of heat transfer between the stack and the heat exchangers. In this study, a specific particle image velocimetry measurement is performed inside a thermoacoustic refrigerator. Acoustic velocity is measured using synchronization and phase-averaging. The measurement method is validated inside a void resonator by successfully comparing experimental data with an acoustic plane wave model. Velocity is measured inside the oscillating boundary layers, between the plates of the stack, and compared to a linear model. The flow behind the stack is characterized, and it shows the generation of symmetric pairs of counter-rotating vortices at the end of the stack plates at low acoustic pressure level. As the acoustic pressure level increases, detachment of the vortices and symmetry breaking are observed.

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

    PubMed Central

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

    2014-01-01

    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

  1. Image of nonlinear structures of heterogeneous media using the second harmonic in scanning acoustical microscope

    NASA Astrophysics Data System (ADS)

    Severin, Fedar M.; O'Neill, Brian; Maev, Roman Gr.

    2000-05-01

    Scanning acoustic microscopy (SAM) images are created on the basis of sound reflection from sharp overfall of acoustical impedance. For that reason any internal structural components and inclusions with similar impedance values will be resolved with certain difficulties. In such particular cases, acoustical nonlinear phenomena could provide very important additional information. Interface between two media at certain conditions can be a very effective source of the second harmonic. It is still correct even in the case of exact equality of acoustical impedance of this media, when regular sound wave "can't recognize" that interface. The source of such concentrated nonlinearity is either the difference of nonlinear parameters of the heterogeneous media (material nonlinearity) or weak, "breaking" junction inside this structure (contact nonlinearity). The image in second harmonic reproduces the gradient distributions of nonlinearity parameters in the specimen. Such kind of image processing can provide a unique opportunity to detect small (less then wavelength) grains, cracks, inclusions and other inhomogeneous which can't be resolved using basic frequency. In our experiments, we used the nonlinear mode in the SAM with a basic frequency of 25 MHz. For this reason, the filter-amplifier with a frequency of 50 MHz and bandwidth of 4 MHz was included into the receiving part. As a result of decreasing the receiver bandwidth, brush pulses of second harmonic have a significant duration compared with one of fundamental frequency. It also leads to deterioration of spatial resolution in depth, consequently, this configuration of the device is better for investigations of two-dimensional objects. Based on our experiments and theoretical results, we demonstrate that an acoustical microscope nonlinear regime may be as effective an instrument for detecting various non-full contact in layered structures.

  2. ACOUSTICAL IMAGING AND MECHANICAL PROPERTIES OF SOFT ROCK AND MARINE SEDIMENTS

    SciTech Connect

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

    2001-01-31

    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.

  3. The effective use of magnetic resonance imaging in the diagnosis of acoustic neuromas.

    PubMed

    Renowden, S A; Anslow, P

    1993-07-01

    The diagnostic approach to acoustic neuromas is complex but these tumours are infrequent in patients even with a suggestive clinical picture. Easy access to an efficient, reliable and cost effective investigation is desirable. Magnetic resonance imaging is now the imaging modality of choice and this paper shows that it may be used effectively as the sole investigation. T2-weighted (T2W) fast spin echo axial images taking 1 min 37 s to acquire were compared with T1-weighted (T1W) gadolinium-enhanced axial images, taking 5 min 11 s to acquire, in 157 patients. The T2W images were satisfactory alone in 43% of patients and allowed confident diagnosis of seven of the nine acoustic neuromas. Partial volume artefact and CSF flow artefact resulted in equivocal examinations in the remaining patients. Using both sequences in every patient, imaging time was 7 min 41 s and at least 40 patients could be examined in 1 day, thus ensuring efficient patient throughput. We suggest that T2W fast spin echo axial images be routinely obtained and that only when they are equivocal should T1W gadolinium-enhanced axial sequences be employed. PMID:8370215

  4. Acoustic reciprocity of spatial coherence in ultrasound imaging.

    PubMed

    Bottenus, Nick; Üstüner, Kutay F

    2015-05-01

    A conventional ultrasound image is formed by transmitting a focused wave into tissue, time-shifting the backscattered echoes received on an array transducer, and summing the resulting signals. The van Cittert-Zernike theorem predicts a particular similarity, or coherence, of these focused signals across the receiving array. Many groups have used an estimate of the coherence to augment or replace the B-mode image in an effort to suppress noise and stationary clutter echo signals, but this measurement requires access to individual receive channel data. Most clinical systems have efficient pipelines for producing focused and summed RF data without any direct way to individually address the receive channels. We describe a method for performing coherence measurements that is more accessible for a wide range of coherence-based imaging. The reciprocity of the transmit and receive apertures in the context of coherence is derived and equivalence of the coherence function is validated experimentally using a research scanner. The proposed method is implemented on a commercial ultrasound system and in vivo short-lag spatial coherence imaging is demonstrated using only summed RF data. The components beyond the acquisition hardware and beamformer necessary to produce a real-time ultrasound coherence imaging system are discussed. PMID:25965679

  5. Acoustic Reciprocity of Spatial Coherence in Ultrasound Imaging

    PubMed Central

    Bottenus, Nick; Üstüner, Kutay F.

    2015-01-01

    A conventional ultrasound image is formed by transmitting a focused wave into tissue, time-shifting the backscattered echoes received on an array transducer and summing the resulting signals. The van Cittert-Zernike theorem predicts a particular similarity, or coherence, of these focused signals across the receiving array. Many groups have used an estimate of the coherence to augment or replace the B-mode image in an effort to suppress noise and stationary clutter echo signals, but this measurement requires access to individual receive channel data. Most clinical systems have efficient pipelines for producing focused and summed RF data without any direct way to individually address the receive channels. We describe a method for performing coherence measurements that is more accessible for a wide range of coherence-based imaging. The reciprocity of the transmit and receive apertures in the context of coherence is derived and equivalence of the coherence function is validated experimentally using a research scanner. The proposed method is implemented on a Siemens ACUSON SC2000™ultrasound system and in vivo short-lag spatial coherence imaging is demonstrated using only summed RF data. The components beyond the acquisition hardware and beamformer necessary to produce a real-time ultrasound coherence imaging system are discussed. PMID:25965679

  6. Imaging living cells with a combined high-resolution multi-photon-acoustic microscope

    Microsoft Academic Search

    Selma Schenkl; Eike Weiss; Martin Stark; Frank Stracke; Iris Riemann; Robert Lemor; Karsten König

    2007-01-01

    With increasing demand for in-vivo observation of living cells, microscope techniques that do not need staining become more and more important. In this talk we present a combined multi-photon-acoustic microscope with the possibility to measure synchronously properties addressed by ultrasound and two-photon fluorescence. Ultrasound probes the local mechanical properties of a cell, while the high resolution image of the two-photon

  7. High-resolution photoacoustic vascular imaging in vivo using a large-aperture acoustic lens

    Microsoft Academic Search

    Konstantin Maslov; Lihong V. Wang

    2005-01-01

    Reflection-mode photoacoustic microscopy with dark-field laser pulse illumination and high frequency ultrasonic detection is used to non-invasively image blood vessels in the skin in vivo. Dark-field illumination minimizes the interference caused by strong photoacoustic signals from superficial structures. A high numerical-aperture acoustic lens provides high lateral resolution, 45-120 micrometers in this system while a broadband ultrasonic detection system provides high

  8. Three-Dimensional Acoustic Tissue Model: A Computational Tissue Phantom for Image Analyses

    NASA Astrophysics Data System (ADS)

    Mamou, J.; Oelze, M. L.; O'Brien, W. D.; Zachary, J. F.

    A novel methodology to obtain three-dimensional (3D) acoustic tissue models (3DATMs) is introduced. 3DATMs can be used as computational tools for ultrasonic imaging algorithm development and analysis. In particular, 3D models of biological structures can provide great benefit to better understand fundamentally how ultrasonic waves interact with biological materials. As an example, such models were used to generate ultrasonic images that characterize tumor tissue microstructures. 3DATMs can be used to evaluate a variety of tissue types. Typically, excised tissue is fixed, embedded, serially sectioned, and stained. The stained sections are digitally imaged (24-bit bitmap) with light microscopy. Contrast of each stained section is equalized and an automated registration algorithm aligns consecutive sections. The normalized mutual information is used as a similarity measure, and simplex optimization is conducted to find the best alignment. Both rigid and non-rigid registrations are performed. During tissue preparation, some sections are generally lost; thus, interpolation prior to 3D reconstruction is performed. Interpolation is conducted after registration using cubic Hermite polynoms. The registered (with interpolated) sections yield a 3D histologic volume (3DHV). Acoustic properties are then assigned to each tissue constituent of the 3DHV to obtain the 3DATMs. As an example, a 3D acoustic impedance tissue model (3DZM) was obtained for a solid breast tumor (EHS mouse sarcoma) and used to estimate ultrasonic scatterer size. The 3DZM results yielded an effective scatterer size of 32.9 (±6.1) ?m. Ultrasonic backscatter measurements conducted on the same tumor tissue in vivo yielded an effective scatterer size of 33 (±8) ?m. This good agreement shows that 3DATMs may be a powerful modeling tool for acoustic imaging applications

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

    NASA Astrophysics Data System (ADS)

    Seleznev, M.; Vinogradov, A.

    2014-07-01

    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.

  10. Acoustical and optical scattering and imaging of tissues: an overview

    Microsoft Academic Search

    Akira Ishimaru

    2001-01-01

    This talk will first give a general discussion on the ultrasound media characteristics of blood and spectral densities of tissues. The first-order scattering theory, multiple scattering theory, Doppler spectrum, cw and pulse scattering, focused beam, beam spot-size, speckle, texture, and rough interface effects will be presented. Imaging through tissues will then be discussed in terms of temporal and spatial resolutions,

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

    PubMed Central

    2014-01-01

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

  12. Acoustic output of multi-line transmit beamforming for fast cardiac imaging: a simulation study.

    PubMed

    Santos, Pedro; Tong, Ling; Ortega, Alejandra; Løvstakken, Lasse; Samset, Eigil; D'hooge, Jan

    2015-07-01

    Achieving higher frame rates in cardiac ultrasound could unveil short-lived myocardial events and lead to new insights on cardiac function. Multi-line transmit (MLT) beamforming (i.e., simultaneously transmitting multiple focused beams) is a potential approach to achieve this. However, two challenges come with it: first, it leads to cross-talk between the MLT beams, appearing as imaging artifacts, and second, it presents acoustic summation in the near field, where multiple MLT beams overlap. Although several studies have focused on the former, no studies have looked into the implications of the latter on acoustic safety. In this paper, the acoustic field of 4-MLT was simulated and compared with single-line transmit (SLT). The findings suggest that standard MLT does present potential concerns. Compared with SLT, it shows a 2-fold increase in mechanical index (MI) (from 1.0 to 2.3), a 6-fold increase in spatial-peak pulse-average intensity (I(sppa)) (from 99 to 576 W?cm(-2)) and a 12-fold increase in spatial-peak temporalaverage intensity (I(spta)) (from 119 to 1407 mW?cm(-2)). Subsequently, modifications of the transmit pulse and delay line of MLT were studied. These modifications allowed for a change in the spatio-temporal distribution of the acoustic output, thereby significantly decreasing the safety indices (MI = 1.2, I(sppa) = 92 W?cm(-2) and I(spta) = 366 mW?cm(-2)). Accordingly, they help mitigate the concerns around MLT, reducing potential tradeoffs between acoustic safety and image quality. PMID:26168178

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

    NASA Astrophysics Data System (ADS)

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

    2013-11-01

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

  14. Image-Based Fit Modeling for Coupled Elastodynamic and Acoustic Problems

    NASA Astrophysics Data System (ADS)

    Takata, K.; Nakahata, K.; Schubert, F.; Köhler, B.

    2011-06-01

    This paper presents a numerical time domain modeling of acoustic, elastodynamic, and coupled waves. Our simulation tool is based on the finite integration technique (FIT) and combined with an image-based modeling approach. The FIT is a grid-based spatial discretization method that works in conjunction with a leap-frog type explicit scheme. In our simulation, geometries of targets are determined by a digital image, then the processed pixel or voxel data is directly fed into the wave simulation by the FIT. Here the modeling and simulation of the wave propagation in a concrete material including fluid-solid interactions and a non-contact ultrasonic testing are demonstrated.

  15. Comparison of articular cartilage images assessed by high-frequency ultrasound microscope and scanning acoustic microscope

    Microsoft Academic Search

    Yoshihiro Hagiwara; Yoshifumi Saijo; Akira Ando; Yoshito Onoda; Hideaki Suda; Eiichi Chimoto; Kouki Hatori; Eiji Itoi

    Purpose  The purpose of this study was to compare images of a newly developed high-frequency ultrasound imaging system (HFUIS) and\\u000a scanning acoustic microscope (SAM) and to calculate their Pearson product moment correlations with a view to applying HFUIS\\u000a for clinical use.\\u000a \\u000a \\u000a \\u000a \\u000a Methods  Cylindrical cartilage–bone complexes from adult male Sprague-Dawley rats were obtained. The specimens were immersed in normal\\u000a saline and scanned by

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

    PubMed Central

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

    2014-01-01

    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

  17. Acoustic cues to visual detection: a classification image study.

    PubMed

    Pascucci, David; Megna, Nicola; Panichi, Michela; Baldassi, Stefano

    2011-01-01

    A non-informative sound is known to improve contrast detection thresholds for a synchronous visual target (M. Lippert, N. K. Logothetis, & C. Kayser, 2007). We investigated the spatio-temporal characteristics of the mechanisms underlying this crossmodal effect by using a classification image paradigm specifically suited to investigate perceptual templates across both space and time (P. Neri & D. J. Heeger, 2002). A bright bar was embedded in 2D (space-time) dynamic noise and observers were asked to detect its presence in both unimodal (only visual) and bimodal (audio-visual) conditions. Classification image analysis was performed and the 1st and 2nd order kernels were derived. Our results show that the cross-modal facilitation of detection consists in a reduction of activity of the early mechanisms elicited by the onset of the stimulation and not directly involved in the identification of the target. In fact, the sound sharpens the 2nd order kernels (involved in target detection) by suppressing the activation preceding the target, whereas it does not influence the 1st order kernels. These data suggest that the sound affects some non-linear process involved with the detection of a visual stimulus by, decreasing the activity of contrast energy filters temporally uncorrelated with the target, hence reducing temporal uncertainty. PMID:21562032

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

    NASA Astrophysics Data System (ADS)

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

    2010-02-01

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

  19. Valence fluctuations in ferromagnetic 4f systems

    Microsoft Academic Search

    W. Nolting; A. Ramakanth

    1986-01-01

    We investigate the coexistence of ferromagnetism and intermediate valence in 4f systems which have ferromagnetic ground states in the normal-valence phase and fluctuate between a magnetic (J!=0) and a nonmagnetic (J=0) state in the intermediate-valence phase. We use a model which is generated from the well-known s-f model by inclusion of a hybridization term. The alloy analogy of the model

  20. ACOUSTICAL IMAGING AND MECHANICAL PROPERTIES OF SOFT ROCK AND MARINE SEDIMENTS

    SciTech Connect

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

    2002-11-18

    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.

  1. Holographic acoustical lens

    Microsoft Academic Search

    C. G. Stephanis; G. D. Hampsas

    1978-01-01

    The theory of an acoustical lens is presented and the construction of such a lens is described. In the present work three experiments are described, in which images of acoustical objects are formed. With the acoustical lens the intermediate step of the conventional acoustical holography of transferring the acoustical hologram to an optical system is avoided.

  2. ACOUSTICAL IMAGING AND MECHANICAL PROPERTIES OF SOFT ROCK AND MARINE SEDIMENTS

    SciTech Connect

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

    2002-11-18

    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.

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

    PubMed Central

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

    2011-01-01

    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

  4. Signal Processing for Time-Lapse Cell Imaging with Vector-Contrast Scanning Acoustic Microscopy

    NASA Astrophysics Data System (ADS)

    von Buttlar, M.; Mohamed, E. A.; Grill, W.

    Non-invasive and marker-free monitoring of living cells can be accomplished by vector contrast scanning acoustic microscopy. In this paper, the signal processing required for creating time-lapse movies of mesenchymal stem cells is discussed. This includes electronic signal processing, autofocusing and image processing. Prior to each recorded image the focusing transducer is moved away from the sample until no echo signal is received. This allows direct measurement of the offset vector caused by internal lens echoes. The offset vector can then be subtracted from the following vector-contrast image. For subsequent autofocusing the transducer is moved closer to the sample until the maximum of the signal in reflection is passed. The transducer position for the maximum reflected signal is determined by respective software and adjusted accordingly. Autofocusing is a requirement for tiled scans where a piezo-scanner and an automatic microscope stage are combined to increase the field of view. As there are typically thousands of images involved in a single movie, batch image processing routines are required. Customized plugins for ImageJ were developed to combine specialized functions for vector contrast data processing with standard image processing capabilities. The motility of a population of ovine mesenchymal stem cells was continuously recorded for 8 h. The detection scheme including experimental details is presented and applications including time-lapse imaging are demonstrated and discussed.

  5. A novel photoacoustic tomography based on a time-resolved technique and an acoustic lens imaging system

    Microsoft Academic Search

    Yongheng He; Zhilie Tang; Zhanxu Chen; Wei Wan; Jianghua Li

    2006-01-01

    A novel photoacoustic (PA) tomographic method, which is based on a time-resolved technique and an acoustic lens imaging system, is presented in this paper. A YAG laser operating at 532 nm with a 7 ns pulse width and 10 mJ optical pulse is employed as the excitation source to irradiate the tissue. PA signals generated from the tissue are imaged

  6. Numerical Analysis of an Underwater Acoustic Lens System for Ambient Noise Imaging using Finite Difference Time Domain Method

    Microsoft Academic Search

    Kazuyoshi Mori; A. Miyazaki; H. Ogasawara; T. Yokoyama; T. Nakamura

    2006-01-01

    Ambient noise imaging (ANI) is the revolutionary idea of detecting undersea objects using the ocean's background noise. In this study, in order to realize an ANI system, sound fields focused by an acoustic lens system constructed with a single biconcave lens were analyzed using the 2D finite difference time domain (FDTD) method. By comparing the image points and -3 dB

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

    SciTech Connect

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

    2002-12-12

    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.

  8. Imaging of acoustic waves induced by excimer laser ablation of the cornea

    NASA Astrophysics Data System (ADS)

    Rossi, Francesca; Pini, Roberto; Siano, Salvatore; Salimbeni, Renzo

    1996-12-01

    In this present study a pump-and-probe imaging set up was arranged to image and analyze the evolution of pressure waves induced by ArF ablation of the cornea, during their propagation into the eyeball. In vitro experiments simulating the effects of clinical PRK have been performed by using an artificial model of the human eyeball, composed of a cell filled with hyaluronic acid gel with a sample of freshly excised bovine cornea placed on the gel surface. LAser irradiation was provided at a fluence of 180 mJ/cm2. Irradiation spot diameters were varied in the range 2.0-5.0 mm. Images of the traveling acoustic waves evidenced diffraction effects, related to the diameter of laser spots on the corneal surface.

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

    SciTech Connect

    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

    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.

  10. Improving viewing region of 4f optical system for holographic displays

    NASA Astrophysics Data System (ADS)

    Kurihara, Takayuki; Takaki, Yasuhiro

    2011-08-01

    A 4f optical system with a single-sideband filter has been used for electronic holographic displays in order to obtain a reconstructed image without a conjugate image and zero-order diffraction light. However, the viewing region is inclined, and the viewing region in which an entire reconstructed image can be viewed is limited. In the present study, one of the Fourier transform lenses constituting the 4f optical system is shifted to correct the viewing region inclination. Moreover, a screen lens is added in the image plane of the 4f optical system to maximize the viewing region. The inclination of the viewing region can also be corrected by shifting the screen lens instead of shifting the Fourier transform lens. Experimental verifications of these corrections are described.

  11. The utility of acoustic radiation force impulse imaging in diagnosing acute appendicitis and staging its severity

    PubMed Central

    Göya, Cemil; Hamidi, Cihad; Okur, Mehmet Hanifi; ?çer, Mustafa; O?uz, Abdullah; Hattapo?lu, Salih; Çetinçakmak, Mehmet Güli; Teke, Memik

    2014-01-01

    PURPOSE The aim of this study was to investigate the feasibility of using acoustic radiation force impulse (ARFI) imaging to diagnose acute appendicitis. METHODS Abdominal ultrasonography (US) and ARFI imaging were performed in 53 patients that presented with right lower quadrant pain, and the results were compared with those obtained in 52 healthy subjects. Qualitative evaluation of the patients was conducted by Virtual Touch™ tissue imaging (VTI), while quantitative evaluation was performed by Virtual Touch™ tissue quantification (VTQ) measuring the shear wave velocity (SWV). The severity of appendix inflammation was observed and rated using ARFI imaging in patients diagnosed with acute appendicitis. Alvarado scores were determined for all patients presenting with right lower quadrant pain. All patients diagnosed with appendicitis received appendectomies. The sensitivity and specificity of ARFI imaging relative to US was determined upon confirming the diagnosis of acute appendicitis via histopathological analysis. RESULTS The Alvarado score had a sensitivity and specificity of 70.8% and 20%, respectively, in detecting acute appendicitis. Abdominal US had 83.3% sensitivity and 80% specificity, while ARFI imaging had 100% sensitivity and 98% specificity, in diagnosing acute appendicitis. The median SWV value was 1.11 m/s (range, 0.6–1.56 m/s) for healthy appendix and 3.07 m/s (range, 1.37–4.78 m/s) for acute appendicitis. CONCLUSION ARFI imaging may be useful in guiding the clinical management of acute appendicitis, by helping its diagnosis and determining the severity of appendix inflammation. PMID:25323836

  12. Acoustic Radiation Force Impulse (ARFI) Imaging of Zebrafish Embryo by High-Frequency Coded Excitation Sequence

    PubMed Central

    Park, Jinhyoung; Lee, Jungwoo; Lau, Sien Ting; Lee, Changyang; Huang, Ying; Lien, Ching-Ling; Shung, K. Kirk

    2011-01-01

    Acoustic radiation force impulse (ARFI) imaging has been developed as a non-invasive method for quantitative illustration of tissue stiffness or displacement. Conventional ARFI imaging (2–10 MHz) has been implemented in commercial scanners for illustrating elastic properties of several organs. The image resolution, however, is too coarse to study mechanical properties of micro-sized objects such as cells. This article thus presents a high-frequency coded excitation ARFI technique, with the ultimate goal of displaying elastic characteristics of cellular structures. Tissue mimicking phantoms and zebrafish embryos are imaged with a 100-MHz lithium niobate (LiNbO3) transducer, by cross-correlating tracked RF echoes with the reference. The phantom results show that the contrast of ARFI image (14 dB) with coded excitation is better than that of the conventional ARFI image (9 dB). The depths of penetration are 2.6 and 2.2 mm, respectively. The stiffness data of the zebrafish demonstrate that the envelope is harder than the embryo region. The temporal displacement change at the embryo and the chorion is as large as 36 and 3.6 ?m. Consequently, this high-frequency ARFI approach may serve as a remote palpation imaging tool that reveals viscoelastic properties of small biological samples. PMID:22101757

  13. In vivo Assessment of Myocardial Stiffness with Acoustic Radiation Force Impulse Imaging

    PubMed Central

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

    2007-01-01

    Acoustic radiation force impulse (ARFI) imaging has been demonstrated to be capable of visualizing variations in local stiffness within soft tissue. Recent advances in ARFI beam sequencing and parallel imaging have shortened acquisition times and lessened transducer heating to a point where ARFI acquisitions can be executed at high frame rates on commercially available diagnostic scanners. In vivo ARFI images were acquired with a linear array placed on an exposed canine heart. The electrocardiogram (ECG) was also recorded. When co-registered with the ECG, ARFI displacement images of the heart reflect the expected myocardial stiffness changes during the cardiac cycle. A radiofrequency ablation was performed on the epicardial surface of the left ventricular free wall, creating a small lesion that did not vary in stiffness during a heartbeat, though continued to move with the rest of the heart. ARFI images showed a hemispherical, stiffer region at the ablation site whose displacement magnitude and temporal variation through the cardiac cycle were less than the surrounding untreated myocardium. Sequences with radiation force pulse amplitudes set to zero were acquired to measure potential cardiac motion artifacts within the ARFI images. The results show promise for real-time cardiac ARFI imaging. PMID:17698282

  14. The development of 3-D image processing acoustic simulator for under sodium viewing technology

    SciTech Connect

    Suzuki, Takehiko; Shioyama, Tsutomu; Karasawa, Hirokazu [Toshiba Corp., Kawasaki (Japan). Energy and Mechanical Research Labs.; Furukawa, Hiromitsu; Ashida, Takako [JEOL System Technology, Tokyo (Japan)

    1996-08-01

    One of the technologies indispensable for development of USV is the simulation technology for evaluating the characteristics of ultrasonic acoustic propagation under sodium in the reactor vessel. In this report, the sound sources superimposed method (SOSUM) is introduced as the simulation technology. In SOSUM, at first , the ultrasonic echoes, which are transmitted from the transmitters and reflected by structures, are calculated as reflecting sound sources. Then, ultrasonic time-series waves received on each receiver are expressed as superimposition of contribution from all transmitted sound sources and reflecting sound sources. The extension of SOSUM to inhomogeneous media is discussed. When temperature fluctuation exists along the ultrasonic transmitting path, acoustic characteristics are inhomogeneous. In this case, the inhomogeneous media are divided to many small divisions in which acoustic characteristics are regarded as homogeneous. However, the extended SOSUM requires huge calculation volume, and thus higher speed techniques are necessary for practical use. In this report, the higher speed techniques with parallel processing are proved to be effective for SOSUM. It is shown that for practical use of 3-D image processing simulator of USV, parallel processing hardware with a high ability of floating point arithmetic and a capability of executing independent code for each processor is needed.

  15. Acoustic property reconstruction of a neonate Yangtze finless porpoise's (Neophocaena asiaeorientalis) head based on CT imaging.

    PubMed

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

    2015-01-01

    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

  16. Acoustic quasi-holographic images of scattering by vertical cylinders from one-dimensional bistatic scans.

    PubMed

    Baik, Kyungmin; Dudley, Christopher; Marston, Philip L

    2011-12-01

    When synthetic aperture sonar (SAS) is used to image elastic targets in water, subtle features can be present in the images associated with the dynamical response of the target being viewed. In an effort to improve the understanding of such responses, as well as to explore alternative image processing methods, a laboratory-based system was developed in which targets were illuminated by a transient acoustic source, and bistatic responses were recorded by scanning a hydrophone along a rail system. Images were constructed using a relatively conventional bistatic SAS algorithm and were compared with images based on supersonic holography. The holographic method is a simplification of one previously used to view the time evolution of a target's response [Hefner and Marston, ARLO 2, 55-60 (2001)]. In the holographic method, the space-time evolution of the scattering was used to construct a two-dimensional image with cross range and time as coordinates. Various features for vertically hung cylindrical targets were interpreted using high frequency ray theory. This includes contributions from guided surface elastic waves, as well as transmitted-wave features and specular reflection. PMID:22225041

  17. Ultrasound imaging software framework for real-time monitoring of acoustic ablation therapy

    NASA Astrophysics Data System (ADS)

    Kang, Hyun-Jae; Deshmukh, Nishikant P.; Stolka, Philipp; Burdette, E. Clif; Boctor, Emad M.

    2012-03-01

    The concern with interstitial ablative therapy for a treatment of hepatic tumors has been growing. In spite of advances in these therapies, there are several technical challenges due to tissue deformation and target motion: localization of the tumor and monitoring for ablator's tip and thermal dose in heated tissue. In the previous work, a steerable acoustic ablator, called ACUSITT, for targeting of ablation tip accurately into tumor area has been developed. However, real-time monitoring techniques for providing image feedback of the ablation tip positioning and thermal dose deposited in the tissue by heating are still needed. In this paper, a new software framework for real-time monitoring ablative therapy during pre- and intra-operation is presented. The software framework provides ultrasound Brightness Mode (B-Mode) image and elastography simultaneously and with real-time. A position of ablator's tip and a region of heated tissue are monitored on B-Mode image, because the image represents tissue morphology. Furthermore, ultrasound elasticity image is used for finding a boundary and region of tumor on pre-ablation, and monitoring thermal dose in tissue during ablation. By providing B-Mode image and elastography at the same time, reliable information for monitoring thermal therapy can be offered.

  18. Acoustic wavefield and Mach wave radiation of flashing arcs in strombolian explosion measured by image luminance

    NASA Astrophysics Data System (ADS)

    Genco, Riccardo; Ripepe, Maurizio; Marchetti, Emanuele; Bonadonna, Costanza; Biass, Sebastien

    2014-10-01

    Explosive activity often generates visible flashing arcs in the volcanic plume considered as the evidence of the shock-front propagation induced by supersonic dynamics. High-speed image processing is used to visualize the pressure wavefield associated with flashing arcs observed in strombolian explosions. Image luminance is converted in virtual acoustic signal compatible with the signal recorded by pressure transducer. Luminance variations are moving with a spherical front at a 344.7 m/s velocity. Flashing arcs travel at the sound speed already 14 m above the vent and are not necessarily the evidence of a supersonic explosive dynamics. However, seconds later, the velocity of small fragments increases, and the spherical acousto-luminance wavefront becomes planar recalling the Mach wave radiation generated by large scale turbulence in high-speed jet. This planar wavefront forms a Mach angle of 55° with the explosive jet axis, suggesting an explosive dynamics moving at Mo = 1.22 Mach number.

  19. Density Change of an Oxidized Nuclear Graphite by Acoustic Microscopy and Image Processing

    SciTech Connect

    Chi, Se Hwan [Korea Atomic Energy Research Institute; Contescu, Cristian I [ORNL; Burchell, Timothy D [ORNL

    2009-01-01

    The strong correlation between the density and the physical and mechanical properties of graphite suggests that the method of nondestructive density evaluation could be developed into a characterization technique of great value for the overall improvement of safety of graphite moderator reactors. In this study, the oxidation-induced density changes in nuclear graphite for VHTR were determined by a conventional destructive bulk density measurement method (BM), and by a new non-destructive method based on acoustic microscopy and image processing (AM). The results were compared in order to validate the applicability of the latter method. For a direct comparison of the results from both measurements, two specimens were prepared from a cylindrical graphite sample (1 inch diameter and 1 inch height, oxidized to 10% weight loss at 700 oC in air for 5 hours). The specimens were used for characterization by BM and AM methods, respectively. The results show that, even with a large standard deviation of the AM, the density changing trend from both methods appeared the same. Present observation may be attributed to the fact that AM images reflect characteristic density changes of the graphite sample through the acoustic impedance changes. This study demonstrates the possibility of using AM as a nondestructive technique for the evaluation of density changes in graphite when a database is prepared through a systematic series of experiments.

  20. Acoustic radiation force impulse and supersonic shear imaging versus transient elastography for liver fibrosis assessment.

    PubMed

    Sporea, Ioan; Bota, Simona; Jurchis, Ana; Sirli, Roxana; Gr?dinaru-Tasc?u, Oana; Popescu, Alina; Ratiu, Iulia; Szilaski, Milana

    2013-11-01

    Our study compared three elastographic methods--transient elastography (TE), acoustic radiation force impulse (ARFI) imaging and supersonic shear imaging (SSI)--with respect to the feasibility of their use in liver fibrosis evaluation. We also compared the performance of ARFI imaging and SSI, with TE as the reference method. The study included 332 patients, with or without hepatopathies, in which liver stiffness was evaluated using TE, ARFI and SSI. Reliable measurements were defined as a median value of 10 (TE, ARFI imaging) or 5 (SSI) liver stiffness measurements with a success rate ?60% and an interquartile range interval <30%. A significantly higher percentage of reliable measurements were obtained using ARFI than by using TE and SSI: 92.1% versus 72.2% (p < 0.0001) and 92.1% versus 71.3% (p < 0.0001). Higher body mass index and older age were significantly associated with inability to obtain reliable measurements of liver stiffness using TE and SSI. In 55.4% of patients, reliable liver stiffness measurements were obtained using all three elastographic methods, and ARFI imaging and TE were similarly accurate in diagnosing significant fibrosis and cirrhosis, with TE as the reference method. PMID:23932281

  1. 23 CFR 774.3 - Section 4(f) approvals.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...2013-04-01 2013-04-01 false Section 4(f) approvals. 774.3 Section 774.3 Highways...WATERFOWL REFUGES, AND HISTORIC SITES (SECTION 4(F)) § 774.3 Section 4(f) approvals. The Administration may not...

  2. 23 CFR 774.3 - Section 4(f) approvals.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...2014-04-01 2014-04-01 false Section 4(f) approvals. 774.3 Section 774.3 Highways...WATERFOWL REFUGES, AND HISTORIC SITES (SECTION 4(f)) § 774.3 Section 4(f) approvals. The Administration may not...

  3. 23 CFR 774.3 - Section 4(f) approvals.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...2011-04-01 2011-04-01 false Section 4(f) approvals. 774.3 Section 774.3 Highways...WATERFOWL REFUGES, AND HISTORIC SITES (SECTION 4(F)) § 774.3 Section 4(f) approvals. The Administration may not...

  4. 23 CFR 774.3 - Section 4(f) approvals.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...2012-04-01 2012-04-01 false Section 4(f) approvals. 774.3 Section 774.3 Highways...WATERFOWL REFUGES, AND HISTORIC SITES (SECTION 4(F)) § 774.3 Section 4(f) approvals. The Administration may not...

  5. 77 FR 321 - Section 4(f) Policy Paper

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-04

    ...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...

  6. 77 FR 42802 - Section 4(f) Policy Paper

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-20

    ...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...

  7. A novel photoacoustic tomography based on a time-resolved technique and an acoustic lens imaging system.

    PubMed

    He, Yongheng; Tang, Zhilie; Chen, Zhanxu; Wan, Wei; Li, Jianghua

    2006-05-21

    A novel photoacoustic (PA) tomographic method, which is based on a time-resolved technique and an acoustic lens imaging system, is presented in this paper. A YAG laser operating at 532 nm with a 7 ns pulse width and 10 mJ optical pulse is employed as the excitation source to irradiate the tissue. PA signals generated from the tissue are imaged onto a multi-element linear array transducer with an acoustic lens. A 64 electronic switch is efficiently used for changing the parallel PA signals into a series. The proposed method directly provides PA images without any complex reconstruction algorithms. With the time-resolved technique, tomographic imaging can be achieved successfully. The results show that the images agree well with the original samples. PMID:16675875

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

    PubMed Central

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

    2013-01-01

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

  9. Preliminary study of copper oxide nanoparticles acoustic and magnetic properties for medical imaging

    NASA Astrophysics Data System (ADS)

    Perlman, Or; Weitz, Iris S.; Azhari, Haim

    2015-03-01

    The implementation of multimodal imaging in medicine is highly beneficial as different physical properties may provide complementary information, augmented detection ability, and diagnosis verification. Nanoparticles have been recently used as contrast agents for various imaging modalities. Their significant advantage over conventional large-scale contrast agents is the ability of detection at early stages of the disease, being less prone to obstacles on their path to the target region, and possible conjunction to therapeutics. Copper ions play essential role in human health. They are used as a cofactor for multiple key enzymes involved in various fundamental biochemistry processes. Extremely small size copper oxide nanoparticles (CuO-NPs) are readily soluble in water with high colloidal stability yielding high bioavailability. The goal of this study was to examine the magnetic and acoustic characteristics of CuO-NPs in order to evaluate their potential to serve as contrast imaging agent for both MRI and ultrasound. CuO-NPs 7nm in diameter were synthesized by hot solution method. The particles were scanned using a 9.4T MRI and demonstrated a concentration dependent T1 relaxation time shortening phenomenon. In addition, it was revealed that CuO-NPs can be detected using the ultrasonic B-scan imaging. Finally, speed of sound based ultrasonic computed tomography was applied and showed that CuO-NPs can be clearly imaged. In conclusion, the preliminary results obtained, positively indicate that CuO-NPs may be imaged by both MRI and ultrasound. The results motivate additional in-vivo studies, in which the clinical utility of fused images derived from both modalities for diagnosis improvement will be studied.

  10. ACOUSTICAL IMAGING AND MECHANICAL PROPERTIES OF SOFT ROCK AND MARINE SEDIMENTS

    SciTech Connect

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

    2001-04-01

    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.

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

    SciTech Connect

    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

    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.

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

    NASA Astrophysics Data System (ADS)

    Toda, Kohji; Sawaguchi, Akihiro

    1991-01-01

    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.

  13. Full-Wave Iterative Image Reconstruction in Photoacoustic Tomography With Acoustically Inhomogeneous Media

    PubMed Central

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

    2014-01-01

    Existing approaches to image reconstruction in photoacoustic computed tomography (PACT) with acoustically heterogeneous media are limited to weakly varying media, are computationally burdensome, and/or cannot effectively mitigate the effects of measurement data incompleteness and noise. In this work, we develop and investigate a discrete imaging model for PACT that is based on the exact photoacoustic (PA) wave equation and facilitates the circumvention of these limitations. A key contribution of the work is the establishment of a procedure to implement a matched forward and backprojection operator pair associated with the discrete imaging model, which permits application of a wide-range of modern image reconstruction algorithms that can mitigate the effects of data incompleteness and noise. The forward and backprojection operators are based on the k-space pseudospectral method for computing numerical solutions to the PA wave equation in the time domain. The developed reconstruction methodology is investigated by use of both computer-simulated and experimental PACT measurement data. PMID:23529196

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

    PubMed Central

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

    2013-01-01

    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

  15. A novel application of time-reversed acoustics: Salt-dome flank imaging using walkaway VSP surveys

    Microsoft Academic Search

    Mark E. Willis; Rongrong Lu; Xander Campman; M. Nafi Toksöz; Yang Zhang; Maarten V. de Hoop

    2006-01-01

    In this paper we present initial results of applying Time-Reversed Acoustics (TRA) technology to salt- dome flank, seismic imaging. We created a set of syn- thetic traces representing a multilevel, walkaway VSP for a model composed of a simplified Gulf of Mexico vertical-velocity gradient and an embedded salt dome. We first applied the concepts of TRA to the synthetic traces

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

    PubMed Central

    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

    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

  17. Imaging of 3D Ocean Turbulence Microstructure Using Low Frequency Acoustic Waves

    NASA Astrophysics Data System (ADS)

    Minakov, Alexander; Kolyukhin, Dmitriy; Keers, Henk

    2015-04-01

    In the past decade the technique of imaging the ocean structure with low-frequency signal (Hz), produced by air-guns and typically employed during conventional multichannel seismic data acquisition, has emerged. The method is based on extracting and stacking the acoustic energy back-scattered by the ocean temperature and salinity micro- and meso-structure (1 - 100 meters). However, a good understanding of the link between the scattered wavefield utilized by the seismic oceanography and physical processes in the ocean is still lacking. We describe theory and the numerical implementation of a 3D time-dependent stochastic model of ocean turbulence. The velocity and temperature are simulated as homogeneous Gaussian isotropic random fields with the Kolmogorov-Obukhov energy spectrum in the inertial subrange. Numerical modeling technique is employed for sampling of realizations of random fields with a given spatial-temporal spectral tensor. The model used is shown to be representative for a wide range of scales. Using this model, we provide a framework to solve the forward and inverse acoustic scattering problem using marine seismic data. Our full-waveform inversion method is based on the ray-Born approximation which is specifically suitable for the modelling of small velocity perturbations in the ocean. This is illustrated by showing a good match between synthetic seismograms computed using ray-Born and synthetic seismograms produced with a more computationally expensive finite-difference method.

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

    SciTech Connect

    P Oshkai; M Geveci; D Rockwell; M Pollack

    2004-05-24

    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.

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

    NASA Astrophysics Data System (ADS)

    Paul, Shirshendu

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2012-07-01

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

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

    NASA Astrophysics Data System (ADS)

    Shen, Changle; Xie, Wenjun; Wei, Bingbo

    2010-12-01

    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.

  2. Precisely shaped acoustic ablation of tumors utilizing steerable needle and 3D ultrasound image guidance

    NASA Astrophysics Data System (ADS)

    Boctor, Emad M.; Stolka, Philipp; Kang, Hyun-Jae; Clarke, Clyde; Rucker, Caleb; Croom, Jordon; Burdette, E. Clif; Webster, Robert J., III

    2010-02-01

    Many recent studies have demonstrated the efficacy of interstitial ablative approaches for the treatment of hepatic tumors. Despite these promising results, current systems remain highly dependent on operator skill, and cannot treat many tumors because there is little control of the size and shape of the zone of necrosis, and no control over ablator trajectory within tissue once insertion has taken place. Additionally, tissue deformation and target motion make it extremely difficult to place the ablator device precisely into the target. Irregularly shaped target volumes typically require multiple insertions and several overlapping (thermal) lesions, which are even more challenging to accomplish in a precise, predictable, and timely manner without causing excessive damage to surrounding normal tissues. In answer to these problems, we have developed a steerable acoustic ablator called the ACUSITT with the ability of directional energy delivery to precisely shape the applied thermal dose . In this paper, we address image guidance for this device, proposing an innovative method for accurate tracking and tool registration with spatially-registered intra-operative three-dimensional US volumes, without relying on an external tracking device. This method is applied to guid-ance of the flexible, snake-like, lightweight, and inexpensive ACUSITT to facilitate precise placement of its ablator tip within the liver, with ablation monitoring via strain imaging. Recent advancements in interstitial high-power ultrasound applicators enable controllable and penetrating heating patterns which can be dynamically altered. This paper summarizes the design and development of the first synergistic system that integrates a novel steerable interstitial acoustic ablation device with a novel trackerless 3DUS guidance strategy.

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

    PubMed

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

    2014-04-01

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

  4. An electrochemical and high-speed imaging study of micropore decontamination by acoustic bubble entrapment.

    PubMed

    Offin, Douglas G; Birkin, Peter R; Leighton, Timothy G

    2014-03-14

    Electrochemical and high-speed imaging techniques are used to study the abilities of ultrasonically-activated bubbles to clean out micropores. Cylindrical pores with dimensions (diameter × depth) of 500 ?m × 400 ?m (aspect ratio 0.8), 125 ?m × 350 ?m (aspect ratio 2.8) and 50 ?m × 200 ?m (aspect ratio 4.0) are fabricated in glass substrates. Each pore is contaminated by filling it with an electrochemically inactive blocking organic material (thickened methyl salicylate) before the substrate is placed in a solution containing an electroactive species (Fe(CN)6(3-)). An electrode is fabricated at the base of each pore and the Faradaic current is used to monitor the decontamination as a function of time. For the largest pore, decontamination driven by ultrasound (generated by a horn type transducer) and bulk fluid flow are compared. It is shown that ultrasound is much more effective than flow alone, and that bulk fluid flow at the rates used cannot decontaminate the pore completely, but that ultrasound can. In the case of the 125 ?m pore, high-speed imaging is used to elucidate the cleaning mechanisms involved in ultrasonic decontamination and reveals that acoustic bubble entrapment is a key feature. The smallest pore is used to explore the limits of decontamination and it is found that ultrasound is still effective at this size under the conditions employed. PMID:24477554

  5. Cycloidal order of 4f moments as a probe of chiral domains in DyMnO?.

    PubMed

    Schierle, E; Soltwisch, V; Schmitz, D; Feyerherm, R; Maljuk, A; Yokaichiya, F; Argyriou, D N; Weschke, E

    2010-10-15

    Using soft x-ray diffraction at the Dy-M? resonance, pronounced circular dichroism in the ferroelectric phase of DyMnO? is observed in connection with sizable b and c components of the Dy-4f magnetic moments. This provides strong evidence for cycloidal order of the 4f moments, corroborating that inversion-symmetry breaking in this material is not accomplished by the Mn spins alone. The 4f circular dichroism allows us to image multiferroic domains that are imprinted on the surface of DyMnO? using the local charging by the x-ray beam via the photoelectric effect. PMID:21231008

  6. Experimental results for a prototype 3-D acoustic imaging system using an ultra-sparse planar array

    NASA Astrophysics Data System (ADS)

    Impagliazzo, John M.; Chiang, Alice M.; Broadstone, Steven R.

    2002-11-01

    A handheld high resolution sonar has been under development to provide Navy Divers with a 3-D acoustic imaging system for mine reconnaissance. An ultra-sparse planar array, consisting of 121 1 mm x1 mm, 2 MHz elements, was fabricated to provide 3-D acoustic images. The array was 10 cm x10 cm. A full array at this frequency with elements at half-wavelength spacing would consist of 16384 elements. The first phase of testing of the planar array was completed in September 2001 with the characterization of the array in the NUWC Acoustic Test Facility (ATF). The center frequency was 2 MHz with a 667 kHz bandwidth. A system-level technology demonstration will be conducted in July 2002 with a real-time beamformer and near real-time 3-D imaging software. The demonstration phase consists of imaging simple targets at a range of 3 m in the ATF. Experimental results obtained will be reported on. [Work supported by the Defense Applied Research Project Agency, Advance Technology Office, Dr. Theo Kooij, Program Manager.

  7. Beamforming and imaging using acoustic lenses: Some simulation and experimental results

    Microsoft Academic Search

    Ju Wu; Hongyu Bian

    2010-01-01

    The acoustic lens sonar uses lenses instead of electronic circuitry in conventional sonar for beam-forming, so that the electronics complexity and power consumption can be much reduced. Two acoustic lenses are designed in this paper by using the hybrid geometric\\/wave acoustic model. One is made from the material PMMA(polymethyl methacrylate) and the other is from the material PMP(polymethylpentene). In order

  8. Synthesis and bioevaluation of [(18)F]4-fluoro-m-hydroxyphenethylguanidine ([(18)F]4F-MHPG): a novel radiotracer for quantitative PET studies of cardiac sympathetic innervation.

    PubMed

    Jang, Keun Sam; Jung, Yong-Woon; Sherman, Phillip S; Quesada, Carole A; Gu, Guie; Raffel, David M

    2013-03-15

    A new cardiac sympathetic nerve imaging agent, [(18)F]4-fluoro-m-hydroxyphenethylguanidine ([(18)F]4F-MHPG), was synthesized and evaluated. The radiosynthetic intermediate [(18)F]4-fluoro-m-tyramine ([(18)F]4F-MTA) was prepared and then sequentially reacted with cyanogen bromide and NH4Br/NH4OH to afford [(18)F]4F-MHPG. Initial bioevaluations of [(18)F]4F-MHPG (biodistribution studies in rats and kinetic studies in the isolated rat heart) were similar to results previously reported for the carbon-11 labeled analog [(11)C]4F-MHPG. The neuronal uptake rate of [(18)F]4F-MHPG into the isolated rat heart was 0.68ml/min/g wet and its retention time in sympathetic neurons was very long (T1/2 >13h). A PET imaging study in a nonhuman primate with [(18)F]4F-MHPG provided high quality images of the heart, with heart-to-blood ratios at 80-90min after injection of 5-to-1. These initial kinetic and imaging studies of [(18)F]4F-MHPG suggest that this radiotracer may allow for more accurate quantification of regional cardiac sympathetic nerve density than is currently possible with existing neuronal imaging agents. PMID:23416009

  9. Enlarged acceptance angle of a finite size detector in photoacoustic imaging using acoustic lenses

    Microsoft Academic Search

    Wenfeng Xia; Daniele Piras; Michelle Heijblom; Johan C. G. van Hespen; Spiridon van Veldhoven; Christian Prins; Wiendelt Steenbergen; Ton G. van Leeuwen; Srirang Manohar

    2011-01-01

    A large surface area transducer is preferable to be used to detect extremely weak photoacoustic signals in mammography due to its high sensitivity. The lateral resolution is limited by the small acceptance angle of such a transducer. We introduce an excellent material for an acoustic lens used to enlarge the transducer's acceptance angle. Our acoustic characterizations showed that this material

  10. Effect of Acoustic Power on In Vivo Molecular Imaging with Targeted Microbubbles: Implications for Low-Mechanical Index Real-Time Imaging

    PubMed Central

    Kaufmann, Beat A.; Carr, Chad L.; Belcik, Todd; Xie, Aris; Kron, Benjamin; Yue, Qi; Lindner, Jonathan R.

    2009-01-01

    The aim of this study was to evaluate the influence of acoustic power on ultrasound molecular imaging data with targeted microbubbles. Imaging was performed with a contrast-specific multipulse method at a mechanical index (MI) of 0.18 and 0.97. In vitro imaging was used to measure concentration-intensity relationships and to assess whether damping from microbubble attachment to cultured endothelial cells affects signal enhancement. Power-related differences in signal enhancement were evaluated in vivo by P-selectin-targeted and control microbubble imaging in a murine model of hindlimb ischemia-reperfusion injury. During in vitro experiments there was minimal acoustic damping from microbubble-cell attachment at either MI. Signal enhancement in the in vitro and in vivo experiments was 2-3-fold higher for high-MI compared with low-MI imaging which was due to greater pixel intensity, detection of a greater number of retained microbubbles, and increased point-spread function. Yet, there was a linear relationship between high- and low-MI data indicating that the relative degree of enhancement was similar. We conclude that during molecular imaging high-MI protocols produce more robust targeted signal enhancement than low-MI, although differences in relative enhancement caused by condition or agent are similar. PMID:19910159

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

    PubMed

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

    2013-08-01

    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

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

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

    E-print Network

    Hoop, Martijn de

    2005-01-01

    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 ...

  14. Acoustic Neuroma

    MedlinePLUS

    ... the future. In a benign tumor such as acoustic neuroma, with a very slow cell turnover, it will take some time for the radiation to affect the cells in a way that can be detected clinically or by imaging. Therefore, radiosurgery has a less immediate effect than ...

  15. A full vectorial contrast source inversion scheme for three-dimensional acoustic imaging of both compressibility and density profiles.

    PubMed

    van Dongen, Koen W A; Wright, William M D

    2007-03-01

    Imaging the two acoustic medium parameters density and compressibility requires the use of both the acoustic pressure and velocity wave fields, described via integral equations. Imaging is based on solving for the unknown medium parameters using known measured scattered wave fields, and it is difficult to solve this ill-posed inverse problem directly using a conjugate gradient inversion scheme. Here, a contrast source inversion method is used in which the contrast sources, defined via the product of changes in compressibility and density with the pressure and velocity wave fields, respectively, are computed iteratively. After each update of the contrast sources, an update of the medium parameters is obtained. Total variation as multiplicative regularization is used to minimize blurring in the reconstructed contrasts. The method successfully reconstructed three-dimensional contrast profiles based on changes in both density and compressibility, using synthetic data both with and without 50% white noise. The results were compared with imaging based only on the pressure wave field, where speed of sound profiles were solely based on changes in compressibility. It was found that the results improved significantly by using the full vectorial method when changes in speed of sound depended on changes in both compressibility and density. PMID:17407891

  16. Acoustic imaging of a duct spinning mode by the use of an in-duct circular microphone array.

    PubMed

    Wei, Qingkai; Huang, Xun; Peers, Edward

    2013-06-01

    An imaging method of acoustic spinning modes propagating within a circular duct simply with surface pressure information is introduced in this paper. The proposed method is developed in a theoretical way and is demonstrated by a numerical simulation case. Nowadays, the measurements within a duct have to be conducted using in-duct microphone array, which is unable to provide information of complete acoustic solutions across the test section. The proposed method can estimate immeasurable information by forming a so-called observer. The fundamental idea behind the testing method was originally developed in control theory for ordinary differential equations. Spinning mode propagation, however, is formulated in partial differential equations. A finite difference technique is used to reduce the associated partial differential equations to a classical form in control. The observer method can thereafter be applied straightforwardly. The algorithm is recursive and, thus, could be operated in real-time. A numerical simulation for a straight circular duct is conducted. The acoustic solutions on the test section can be reconstructed with good agreement to analytical solutions. The results suggest the potential and applications of the proposed method. PMID:23742352

  17. ACOUSTICAL IMAGING AND MECHANICAL PROPERTIES OF SOFT ROCK AND MARINE SEDIMENTS

    SciTech Connect

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

    2001-07-01

    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.

  18. 28 CFR 55.8 - Relationship between section 4(f)(4) and section 203(c).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... false Relationship between section 4(f)(4) and section 203(c). 55.8...55.8 Relationship between section 4(f)(4) and section 203(c). (a) The statutory requirements of section 4(f)(4) and section 203(c)...

  19. 28 CFR 55.8 - Relationship between section 4(f)(4) and section 203(c).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... false Relationship between section 4(f)(4) and section 203(c). 55.8...55.8 Relationship between section 4(f)(4) and section 203(c). (a) The statutory requirements of section 4(f)(4) and section 203(c)...

  20. 28 CFR 55.8 - Relationship between section 4(f)(4) and section 203(c).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... false Relationship between section 4(f)(4) and section 203(c). 55.8...55.8 Relationship between section 4(f)(4) and section 203(c). (a) The statutory requirements of section 4(f)(4) and section 203(c)...

  1. 28 CFR 55.8 - Relationship between section 4(f)(4) and section 203(c).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... false Relationship between section 4(f)(4) and section 203(c). 55.8...55.8 Relationship between section 4(f)(4) and section 203(c). (a) The statutory requirements of section 4(f)(4) and section 203(c)...

  2. 77 FR 64836 - Notice of Availability of Draft Environmental Impact Statement (DEIS), Draft Section 4(f...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-23

    ...Impact Statement (DEIS), Draft Section 4(f) Evaluation, Notice of ANILCA Title XI...draft evaluation pursuant to Section 4(f) of the Department of Transportation Act...and resources protected under Section 4(f) of the Department of Transportation...

  3. 28 CFR 55.8 - Relationship between section 4(f)(4) and section 203(c).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... false Relationship between section 4(f)(4) and section 203(c). 55.8...55.8 Relationship between section 4(f)(4) and section 203(c). (a) The statutory requirements of section 4(f)(4) and section 203(c)...

  4. Clinical feasibility study of combined opto-acoustic and ultrasonic imaging modality providing coregistered functional and anatomical maps of breast tumors

    NASA Astrophysics Data System (ADS)

    Zalev, Jason; Clingman, Bryan; Smith, Remie J.; Herzog, Don; Miller, Tom; Stavros, A. Thomas; Ermilov, Sergey; Conjusteau, André; Tsyboulski, Dmitri; Oraevsky, Alexander A.; Kist, Kenneth; Dornbluth, N. C.; Otto, Pamela

    2013-03-01

    We report on findings from the clinical feasibility study of the ImagioTM. Breast Imaging System, which acquires two-dimensional opto-acoustic (OA) images co-registered with conventional ultrasound using a specialized duplex hand-held probe. Dual-wavelength opto-acoustic technology is used to generate parametric maps based upon total hemoglobin and its oxygen saturation in breast tissues. This may provide functional diagnostic information pertaining to tumor metabolism and microvasculature, which is complementary to morphological information obtained with conventional gray-scale ultrasound. We present co-registered opto-acoustic and ultrasonic images of malignant and benign tumors from a recent clinical feasibility study. The clinical results illustrate that the technology may have the capability to improve the efficacy of breast tumor diagnosis. In doing so, it may have the potential to reduce biopsies and to characterize cancers that were not seen well with conventional gray-scale ultrasound alone.

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

    PubMed Central

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

    2009-01-01

    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

  6. Feasibility of Near Real-Time Lesion Assessment During Radiofrequency Catheter Ablation in Humans Using Acoustic Radiation Force Impulse Imaging

    PubMed Central

    Bahnson, Tristram D.; Eyerly, Stephanie A.; Hollender, Peter J.; Doherty, Joshua R.; Kim, Young-Joong; Trahey, Gregg E.; Wolf, Patrick D.

    2015-01-01

    Background Visual confirmation of radiofrequency ablation (RFA) lesions during clinical cardiac ablation procedures could improve procedure efficacy, safety, and efficiency. It was previously shown that acoustic radiation force impulse (ARFI) imaging can identify RFA lesions in vitro and in vivo in an animal model. This is the “first-in-human” feasibility demonstration of intracardiac ARFI imaging of RFA lesions in patients undergoing catheter ablation for atrial flutter (AFL) or atrial fibrillation (AF). Methods and Results Patients scheduled for right atrial (RA) ablation for AFL or left atrial (LA) ablation for drug refractory AF were eligible for imaging. Diastole-gated intracardiac ARFI images were acquired using one of two equipment configurations: (1) a Siemens ACUSON S2000™ ultrasound scanner and 8/10Fr AcuNav™ ultrasound catheter, or (2) a CARTO 3™ integrated Siemens SC2000™ and 10Fr SoundStar™ ultrasound catheter. A total of 11 patients (AFL = 3; AF = 8) were imaged. ARFI images were acquired of ablation target regions, including the RA cavotricuspid isthmus (CTI), and the LA roof, pulmonary vein ostia, posterior wall, posterior mitral valve annulus, and the ridge between the pulmonary vein and LA appendage. ARFI images revealed increased relative myocardial stiffness at ablation catheter contact sites after RFA and at anatomical mapping-tagged RFA treatment sites. Conclusions ARFI images from a pilot group of patients undergoing catheter ablation for AFL and AF demonstrate the ability of this technique to identify intra-procedure RFA lesion formation. The results encourage further refinement of ARFI imaging clinical tools and continued investigation in larger clinical trials. PMID:25132292

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

    SciTech Connect

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

    2001-12-01

    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.

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

    USGS Publications Warehouse

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

    2002-01-01

    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.

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

    PubMed

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

    2014-08-01

    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

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

    PubMed

    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

    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

  11. Integration of acoustic radiation force and optical imaging for blood plasma clot stiffness measurement.

    PubMed

    Wang, Caroline W; Perez, Matthew J; Helmke, Brian P; Viola, Francesco; Lawrence, Michael B

    2015-01-01

    Despite the life-preserving function blood clotting serves in the body, inadequate or excessive blood clot stiffness has been associated with life-threatening diseases such as stroke, hemorrhage, and heart attack. The relationship between blood clot stiffness and vascular diseases underscores the importance of quantifying the magnitude and kinetics of blood's transformation from a fluid to a viscoelastic solid. To measure blood plasma clot stiffness, we have developed a method that uses ultrasound acoustic radiation force (ARF) to induce micron-scaled displacements (1-500 ?m) on microbeads suspended in blood plasma. The displacements were detected by optical microscopy and took place within a micro-liter sized clot region formed within a larger volume (2 mL sample) to minimize container surface effects. Modulation of the ultrasound generated acoustic radiation force allowed stiffness measurements to be made in blood plasma from before its gel point to the stage where it was a fully developed viscoelastic solid. A 0.5 wt % agarose hydrogel was 9.8-fold stiffer than the plasma (platelet-rich) clot at 1 h post-kaolin stimulus. The acoustic radiation force microbead method was sensitive to the presence of platelets and strength of coagulation stimulus. Platelet depletion reduced clot stiffness 6.9 fold relative to platelet rich plasma. The sensitivity of acoustic radiation force based stiffness assessment may allow for studying platelet regulation of both incipient and mature clot mechanical properties. PMID:26042775

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

    E-print Network

    concerns, building facades tend to include multi-layered components such as outer thermal insulation of the samples. The comparison of these measurements with the acoustic activity of the material showed a fair, cause mould problems, bring health problems or form thermal bridges, sinking the overall energetic

  13. Integration of Acoustic Radiation Force and Optical Imaging for Blood Plasma Clot Stiffness Measurement

    PubMed Central

    Wang, Caroline W.; Perez, Matthew J.; Helmke, Brian P.; Viola, Francesco; Lawrence, Michael B.

    2015-01-01

    Despite the life-preserving function blood clotting serves in the body, inadequate or excessive blood clot stiffness has been associated with life-threatening diseases such as stroke, hemorrhage, and heart attack. The relationship between blood clot stiffness and vascular diseases underscores the importance of quantifying the magnitude and kinetics of blood’s transformation from a fluid to a viscoelastic solid. To measure blood plasma clot stiffness, we have developed a method that uses ultrasound acoustic radiation force (ARF) to induce micron-scaled displacements (1-500 ?m) on microbeads suspended in blood plasma. The displacements were detected by optical microscopy and took place within a micro-liter sized clot region formed within a larger volume (2 mL sample) to minimize container surface effects. Modulation of the ultrasound generated acoustic radiation force allowed stiffness measurements to be made in blood plasma from before its gel point to the stage where it was a fully developed viscoelastic solid. A 0.5 wt % agarose hydrogel was 9.8-fold stiffer than the plasma (platelet-rich) clot at 1 h post-kaolin stimulus. The acoustic radiation force microbead method was sensitive to the presence of platelets and strength of coagulation stimulus. Platelet depletion reduced clot stiffness 6.9 fold relative to platelet rich plasma. The sensitivity of acoustic radiation force based stiffness assessment may allow for studying platelet regulation of both incipient and mature clot mechanical properties. PMID:26042775

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

    PubMed Central

    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

    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

  15. MA4F7 Brownian Motion March 16, 2013

    E-print Network

    Sengun, Mehmet Haluk

    MA4F7 Brownian Motion March 16, 2013 Contents 1 Brownian Sample Paths 1 1.1 Brownian Motion Brownian motion as a Markov Process 12 2.1 Markov transition functions Laws for Brownian motion . . . . . . . . . . . . . . . . . . . . . . 21 3 Brownian Martingales 22 4

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

    PubMed

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

    2013-11-01

    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

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

    NASA Astrophysics Data System (ADS)

    Fahey, Brian J.; Trahey, Gregg E.

    2005-04-01

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

  18. Measurement of acoustic velocity in the stack of a thermoacoustic refrigerator using particle image velocimetry

    Microsoft Academic Search

    Arganthaël Berson; Marc Michard; Philippe Blanc-Benon

    2008-01-01

    Thermoacoustic refrigeration systems generate cooling power from a high-amplitude acoustic standing wave. There has recently\\u000a been a growing interest in this technology because of its simple and robust architecture and its use of environmentally safe\\u000a gases. With the prospect of commercialization, it is necessary to enhance the efficiency of thermoacoustic cooling systems\\u000a and more particularly of some of their components

  19. Novel MEMS microshell transducer arrays for high-resolution underwater acoustic imaging applications

    Microsoft Academic Search

    Mark J. Mescher; Ken Houston; Jon J. Bernstein; Greg A. Kirkos; Jinrong Cheng; L. E. Cross

    2002-01-01

    Presents the design, fabrication process and experimental acoustic test data for a novel MEMS-based 2-D ferroelectric ultrasound microshell transducer array. A new 3-D-micromachining technique is used to fabricate a MEMS microshell structure that acts as an ultrasound transducer in the 1-5 MHz range. A rounded sacrificial carbon structure generated by a two-step photo-resist reflow and pyrolysis process provides the shape

  20. Optimal design of a transmit\\/receive system with a reflector and a transducer lens for long-range underwater acoustic imaging

    Microsoft Academic Search

    Jong Taik Oh; Song Bai Park

    1991-01-01

    As a transmitting\\/receiving system for long-range underwater acoustic imaging, the shape of a lens attached to the disk transducer, the shape of a relatively small reflector, and the transducer positioning are optimized so that a plane wave is generated at the plane bounded by the circularly symmetrical reflector edge. The actual field distribution on the aperture plane and the beam

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

    NASA Astrophysics Data System (ADS)

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

    2008-11-01

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

  2. Detecting the Activation of a Self-Healing Mechanism in Concrete by Acoustic Emission and Digital Image Correlation

    PubMed Central

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

    2013-01-01

    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

  3. Comparison of active millimeter-wave and acoustic imaging for weapon detection

    Microsoft Academic Search

    David M. Sheen; H. D. Collins; R. Parks Gribble; Douglas L. McMakin

    1997-01-01

    Millimeter-wave holographic imaging techniques have recently been developed for personnel surveillance applications at airports and other high-security checkpoints. Millimeter- wave imaging is useful for this application since millimeter-waves easily pass through common clothing materials yet are reflected from the human body and any items concealed by clothing. This allows a high-resolution imaging system to form an image revealing items concealed

  4. Kondo Physics in 4 f metals: Gadolinium nanocontacts

    NASA Astrophysics Data System (ADS)

    Olivera, Bernat; Untiedt, Carlos; Scheer, Elke

    2015-03-01

    The study of electron transport in conducting materials at the nanoscale can be carried out by using Scanning Tunneling Microscope (STM) and Mechanically Controllable Break Junction techniques (MCBJ). At such scales, Kondo effect vanishes the magnetic properties of the 3 d transition metals Fe, Co and Ni. The 4 f rare earth metals are an interesting aim of study because of their strong magnetic properties among other things. At our laboratories we have measured gadolinium with both STM and MCBJ techniques. In the spectroscopy measurements of this material we perceive a set of features that could be related to its magnetic properties. The interplay between the 4f7 and 5d1 orbitals from Gd drives us to pose the mechanisms that are involved in the electronic transport properties of these systems.

  5. Acoustics and Vibration Animations

    NSDL National Science Digital Library

    Russell, Daniel A.

    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.

  6. The Possibility of Gain among the 5D-4F Transitions of the Rare Earth Ions

    Microsoft Academic Search

    Janice Kay Lawson

    1992-01-01

    Although a wealth of information exists on the 4f-4f transitions of rare earth ions doped into solid-state materials, relatively little research exists on the 5d -4f transitions present in the same materials. We have studied the 5d-4f transitions of three rare-earth ions in a variety of materials in an attempt to evaluate the potential of the 5d-4f transition as a

  7. Wavefront modulation and subwavelength diffractive acoustics with an acoustic metasurface.

    PubMed

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

    2014-01-01

    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

  8. Wavefront modulation and subwavelength diffractive acoustics with an acoustic metasurface

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

    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.

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

    PubMed Central

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

    2009-01-01

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

  10. Flow sorting and sequencing meadow fescue chromosome 4F.

    PubMed

    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

    2013-11-01

    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

  11. The electronic structure of 4f local moment systems

    NASA Astrophysics Data System (ADS)

    Komesu, Takashi

    Local moment systems, especially the 4f-electron systems, are archetypal candidate materials to investigate the influence of band structure on several magnetic properties of (anti-) ferromagnetism. These magnetic materials are dominated by the strong exchange coupling between the relatively large 4f local moments, mediated by the valence and conduction electrons near the Fermi level (EF), and are model of RKKY type systems. These materials exhibit strong wave vector dependent exchange splitting: the energy difference between majority (spin up) and minority (spin down) bands. The electronic structures in these systems show the significant influence of symmetry and orbital overlap in the band structure. This can be probed with spin-polarized photoemission (SPES) and spin-polarized inverse photoemission (SPIPES). The rare-earth, Gadolinium (Gd) and the rare earth pnictide compound, Erbium Arsenide (ErAs), have been a subject of much discussion regarding band structure because of the "coupled" magnetic and electronic properties. Gadolinium is the great candidate for investigating the electronic structure of a local moment 4f magnet. Gd thin films grown on Mo(112) surface have been studied for a long time because of the strained hcp (4% expansively strained with thickness more than 50 A). Expansive strain enhances the gadolinium magnetism reflected in the electronic structure. In addition, I have found indications of d-f hybridization, in strained Gd(0001). The experimental band structure of ErAs, grown epitaxially on GaAs(100), has been mapped out using photoelectron spectroscopy (PES) and inverse photoemission spectroscopy (IPES). The electronic structure is dominated by bulk bands qualitatively consistent with the calculated band structure, though a number of additional nondispersing multiplet levels can be identified in the valence band structure, as well as at least one surface resonance band. From symmetry selection rules, photoemission provides strong evidence that the Delta5 (or e) symmetry bands are a consequence of hybridization between Er and As, while the Delta1 (or a1) symmetry bands have possible contributions from nonbonding or antibonding states from Er (and/or As). Again, I find indications of 5d-4f hybridization.

  12. Evaluation of Stiffness of the Spastic Lower Extremity Muscles in Early Spinal Cord Injury by Acoustic Radiation Force Impulse Imaging

    PubMed Central

    Cho, Kang Hee

    2015-01-01

    Objective To investigate intrinsic viscoelastic changes using shear wave velocities (SWVs) of spastic lower extremity muscles in patients with early spinal cord injury (SCI) via acoustic radiation force impulse (ARFI) imaging and to evaluate correlation between the SWV values and spasticity. Methods Eighteen patients with SCI within 3 months and 10 healthy adults participated. We applied the ARFI technique to measure SWV of gastrocnemius muscle (GCM) and long head of biceps femoris muscle. Spasticity of ankle and knee joint was assessed by original Ashworth Scale. Results Ten patients with SCI had spasticity. Patients with spasticity had significantly faster SWV for GCM and biceps femoris muscle than those without spasticity (Mann-Whitney U test, p=0.007 and p=0.008) and normal control (p=0.011 and p=0.037, respectively). The SWV values of GCM correlated with the ankle spasticity (Spearman rank teat, p=0.026). There was significant correlation between the SWV values for long head of biceps femoris muscle and knee spasticity (Spearman rank teat, p=0.022). Conclusion ARFI demonstrated a difference in muscle stiffness in the GCM between patients with spastic SCI and those without spasticity. This finding suggested that stiffness of muscles increased in spastic lower extremity of early SCI patients. ARFI imaging is a valuable tool for noninvasive assessment of the stiffness of the spastic muscle and has the potential to identify pathomechanical changes of the tissue associated with SCI.

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

    SciTech Connect

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

    1999-07-01

    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.

  14. Image-guided acoustic hemostasis for hemorrhage in the posterior liver.

    PubMed

    Burgess, Sean; Zderic, Vesna; Vaezy, Shahram

    2007-01-01

    We investigated the use of ultrasound image-guided high intensity focused ultrasound (HIFU) to stop bleeding from injuries in the posterior liver. A HIFU transducer with focal length of 3.5 cm and frequency of 3.2 MHz was integrated with an intraoperative high-resolution ultrasound-imaging probe. Wedge tissue extractions, 30-mm long, 5-mm wide and 8-mm deep, were made in the posterior liver surface of five pigs to induce bleeding. The device was positioned on the anterior surface of the liver and HIFU was applied using ultrasound image-guidance. Hemostasis was achieved in 66 +/- 18 s (mean +/- standard deviation) for 17 HIFU treatments. During 7 min of sham HIFU treatment, none of the control incisions (n = 7) became hemostatic. Ultrasound image-guided HIFU offers a promising method for hemostasis in surgical settings in which the hemorrhage site is hidden and/or not accessible. PMID:17189053

  15. Nonlinear acoustic enhancement in photoacoustic imaging with wideband absorptive nanoemulsion beads

    NASA Astrophysics Data System (ADS)

    Wei, Chen-wei; Lombardo, Michael; Xia, Jinjun; Pelivanov, Ivan; Perez, Camilo; Larson-Smith, Kjersta; Matula, Thomas J.; Pozzo, Danilo; O'Donnell, Matthew

    2014-03-01

    A nanoemulsion contrast agent with a perfluorohexane core and optically absorptive gold nanospheres (GNSs) assembled on the surface, is presented to improve the specificity of photoacoustic (PA) molecular imaging in differentiating targeted cells or aberrant regions from heterogeneous background signals. Compared to distributed GNSs, clustered GNSs at the emulsion oil-water interface produce a red-shifted and broadened absorption spectrum, exhibiting fairly high absorption in the near-infrared region commonly used for deep tissue imaging. Above a certain laser irradiation fluence threshold, a phase transition creating a microbubble in the emulsion core leads to more than 10 times stronger PA signals compared with conventional thermal-expansion-induced PA signals. These signals are also strongly non-linear, as verified by a differential scheme using recorded PA images at different laser fluences. Assuming a linear relation between laser fluence and the PA signal amplitude, differential processing results in nearly perfect suppression of linear sources, but retains a significant residue for the non-linear nanoemulsion with more than 35 dB enhancement. This result demonstrates that contrast specificity can be improved using the nanoemulsion as a targeting agent in PA molecular imaging by suppressing all background signals related to a linear PA response. Furthermore, combined with a system providing simultaneous laser/ultrasound excitation, cavitation-generated bubbles have the potential to be a highly specific contrast agent for ultrasound molecular imaging and harmonic imaging, as well as a targeted means for noninvasive ultrasound-based therapies.

  16. Overview of acoustical technology for nondestructive evaluation

    Microsoft Academic Search

    Robert E. Green Jr.

    1992-01-01

    A brief overview is presented of acoustical techniques for nondestructive evaluation of materials and structures. Among the general topics covered are modes of elastic wave propagation in solid materials, energy flux vector, and nonlinear effects. Included in the section on ultrasonic measurements are ultrasonic attenuation, laser ultrasonics, full-field imaging of acoustic displacements, optical detection of acoustic emission, acousto-ultrasonics, acoustic microscopy,

  17. Comparative expression analysis of POU4F1, POU4F2 and ISL1 in developing mouse cochleovestibular ganglion neurons.

    PubMed

    Deng, Min; Yang, Hua; Xie, Xiaoling; Liang, Guoqing; Gan, Lin

    2014-05-01

    POU-homeodomain and LIM-homeodomain transcription factors are expressed in developing projection neurons within retina, inner ear, dorsal root ganglion, and trigeminal ganglion, and play synergistic roles in their differentiation and survival. Here, using immunohistochemistry, we present a comparative analysis of the spatiotemporal expression pattern of POU4F1, POU4F2, and ISL1 during the development of cochleovestibular ganglion (CVG) neurons in mouse inner ear. At early stages, when otic neurons are first detected in the otic epithelium (OE) and migrate into periotic mesenchyme to form the CVG, POU4F1 and ISL1 are co-expressed in a majority of the delaminated CVG neurons, which are marked by NEUROD1 expression, but POU4F1 is absent in the otic epithelium. The onset of POU4F2 expression starts after that of POU4F1 and ISL1, and is observed in the NEUROD1-negative, post-mitotic CVG neurons. When the CVG neurons innervate the vestibular and cochlear sensory organs, the expression of POU4F1, POU4F2, and ISL1 continues in both vestibular and spiral ganglion cells. Later in development, POU4F1 expression becomes down-regulated in a majority of spiral ganglion (SG) neurons and more neurons express POU4F2 expression while ISL1 expression is maintained. The differential as well as overlapping expression of POU4F1, POU4F2, and ISL1 combined with previous studies suggests possible functional interaction and regulatory relationship of these transcription factors in the development of inner ear neurons. PMID:24709358

  18. Energies of 4f^N and 4f^N-15d States Relative to Host Bands in Rare-earth-doped Fluorides

    Microsoft Academic Search

    C. W. Thiel; M.-F. Joubert; A. Tkachuk

    2005-01-01

    Energies of 4f^N states relative to crystal band states were measured for rare-earth ions in the optical host materials LiYF4, Na0.4Y0.6F2.2, and LaF3 using x-ray photoemission spectroscopy. Spectra were modeled to determine the valence band maximum and 4f^ electron binding energies in each material. These results were combined with 4f^N to 4f^N-15d transition energies to determine 5d binding energies for

  19. REDUCED SCALE EXPERIMENT OF APLANATIC ACOUSTIC LENS FOR DESIGNING AMBIENT NOISE IMAGING SYSTEM

    Microsoft Academic Search

    Kazuyoshi Mori; Hanako Ogasawara; Toshiaki Nakamura; Yuji Sato; Takenobu Tsuchiya; Nobuyuki Endoh

    In our previous studies, we verified that a spherical biconcave lens with an aperture diameter of 2.0 m has a sufficient directional resolution (for example, the beam width is 1 deg at the target center frequency of 60 kHz) for realizing an ambient noise imaging (ANI) system. In this study, we designed an aplanatic lens correcting both spherical and coma

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

    E-print Network

    Wagner, Oliver

    (Isata) and Ultrasonic Power (W) in Medical Composite Ultrasonic Transducers; P. Acevedo, D. Das. Bereiter-Hahn, et al. Development of Three Dimensional Image Analysis System for Computer Aided Diagnosis of the Ferroelectric Domains Pattern in the Ultrasonic Piezo-Mode; M. Kopycinska, et al. A #12;Compar

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

    NASA Astrophysics Data System (ADS)

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

    2011-03-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2011-07-01

    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.

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

    PubMed

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

    2006-12-01

    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

  4. 28 CFR 55.5 - Coverage under section 4(f)(4).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...2013-07-01 false Coverage under section 4(f)(4). 55.5 Section 55.5 Judicial...Coverage § 55.5 Coverage under section 4(f)(4). (a) Coverage formula. Section 4(f)(4) applies to any State or political...

  5. 28 CFR 55.5 - Coverage under section 4(f)(4).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...2014-07-01 false Coverage under section 4(f)(4). 55.5 Section 55.5 Judicial...Coverage § 55.5 Coverage under section 4(f)(4). (a) Coverage formula. Section 4(f)(4) applies to any State or political...

  6. 28 CFR 55.5 - Coverage under section 4(f)(4).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...2011-07-01 false Coverage under section 4(f)(4). 55.5 Section 55.5 Judicial...Coverage § 55.5 Coverage under section 4(f)(4). (a) Coverage formula. Section 4(f)(4) applies to any State or political...

  7. 28 CFR 55.5 - Coverage under section 4(f)(4).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...2010-07-01 false Coverage under section 4(f)(4). 55.5 Section 55.5 Judicial...Coverage § 55.5 Coverage under section 4(f)(4). (a) Coverage formula. Section 4(f)(4) applies to any State or political...

  8. 28 CFR 55.5 - Coverage under section 4(f)(4).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...2012-07-01 false Coverage under section 4(f)(4). 55.5 Section 55.5 Judicial...Coverage § 55.5 Coverage under section 4(f)(4). (a) Coverage formula. Section 4(f)(4) applies to any State or political...

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

    PubMed Central

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

    2013-01-01

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

  10. Extraction of Target Scatterings from Received Transients on Target Detection Trial of Ambient Noise Imaging with Acoustic Lens

    NASA Astrophysics Data System (ADS)

    Mori, Kazuyoshi; Ogasawara, Hanako; Nakamura, Toshiaki; Tsuchiya, Takenobu; Endoh, Nobuyuki

    2012-07-01

    We have already designed and fabricated an aspherical lens with an aperture diameter of 1.0 m to develop a prototype system for ambient noise imaging (ANI). It has also been verified that this acoustic lens realizes a directional resolution, which is a beam width of 1° at the center frequency of 120 kHz over the field of view from -7 to +7°. In this study, a sea trial of silent target detection using the prototype ANI system was conducted under only natural ocean ambient noise at Uchiura Bay, in November of 2010. There were many transients in the received sound. These transients were classified roughly into directly received noises and target scatterings. We proposed a classification method to extract transients of only target scatterings. By analyzing transients extracted as target scatterings, it was verified that the power spectrum density levels of the on-target directions were greater than those of the off-target directions in the higher frequency band over 60 kHz. These results showed that the targets are successfully detected under natural ocean ambient noise, mainly generated by snapping shrimps.

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

    Microsoft Academic Search

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

    1999-01-01

    Ultrasound is an attractive modality for adjunctive characterization of certain breast lesions, but it is not considered specific for cancer and it is not recommended for screening. An imaging technique remarkably different from pulse-echo ultrasound, termed Optical SonographyTM (Advanced Diagnostics, Inc.), uses the through-transmission signal. The method was applied to breast examinations in 41 asymptomatic and symptomatic women ranging in

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

    PubMed Central

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

    2014-01-01

    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

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

    PubMed Central

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

    2015-01-01

    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

  14. 4f3 - 4f25d interconfigurational transitions of Nd3+ions in LiCaAlF6 single crystal

    NASA Astrophysics Data System (ADS)

    Kollia, Z.; Sarantopoulou, Evangelia; Cefalas, Alkiviadis C.; Naumov, A. K.; Korableva, S. L.; Abdulsabirov, R. Y.; Semashko, V. V.

    1998-07-01

    The laser induced fluorescence (LIF) spectrum of LiCaAlF:Nd3+ (LiCAF:Nd) single crystal, pumped by an F2 pulsed discharge molecular laser at 157.6 nm, was obtained in the vacuum ultraviolet (VUV) region of the spectrum. The fluorescence peaks were assigned to the 4f25dyields4f3 dipole allowed transitions of the Nd3+ ion. The LIF spectrum of the crystals, indicates that the 4f3yields4f25d dipole transitions, originate from the low Stark components of the 4K11/2 level of 4f25d configuration. The absorption spectrum of the crystal samples in the VUV was obtained as well. The electric crystal field splits all the levels of 4f25d mixed configuration. We observed seven dipole transitions, between the 4I9/2 ground level of 4f3 configuration and the Stark components of the levels of 4f25d configuration of the Nd3+ ion.

  15. Gradient-induced acoustic and magnetic field fluctuations in a 4T whole-body MR imager

    Microsoft Academic Search

    Yuhua Wu; Blaine A. Chronik; Chris Bowen; Chris K. Mechefske; Brian K. Rutt

    2000-01-01

    Both the acoustic and magnetic fluctuation frequency response functions for a Siemens AS25 body gradient coil inside a 4 Tesla whole-body MR system were measured and analyzed in this study. In an attempt to correlate the acoustic noise inside the gradient coil with magnetic field oscillations, triangular and trap- ezoidal gradient impulses of varying amplitudes and widths were used to

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  17. Acoustic Remote Sensing

    NASA Astrophysics Data System (ADS)

    Dowling, David R.; Sabra, Karim G.

    2015-01-01

    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.

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

    PubMed

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

    2014-07-01

    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

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

    NASA Astrophysics Data System (ADS)

    Yang, Xinmai; Cleveland, Robin O.

    2005-01-01

    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. .

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

    PubMed Central

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

    2014-01-01

    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

  1. Observations of the volume flux of a seafloor hydrothermal plume using an acoustic imaging sonar

    NASA Astrophysics Data System (ADS)

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

    2013-07-01

    We present a 26 day time series (October 2010) of physical properties (volume flux, flow velocity, expansion rate) of a vigorous deep-sea hydrothermal plume measured using our Cabled Observatory Vent Imaging Sonar (COVIS), which is connected to the Northeast Pacific Time Series Underwater Experiment Canada Cabled Observatory at the Main Endeavour Field on the Juan de Fuca Ridge. COVIS quantitatively monitors the initial buoyant rise of the plume from ˜5 m to ˜15 m above the vents. The time series exhibits temporal variations of the plume vertical volume flux (1.93-5.09 m3/s ), centerline vertical velocity component (0.11-0.24 m/s ) and expansion rate (0.082-0.21 m/m ); these variations have major spectral peaks at semidiurnal (˜2 cycle/day) and inertial oscillation (˜1.5 cycle/day) frequencies. The plume expansion rate (average ˜0.14 m/m ) is inversely proportional to the plume centerline vertical velocity component (coefficient of determination R2˜0.5). This inverse proportionality, as well as the semidiurnal frequency, indicates interaction between the plume and ambient ocean currents consistent with an entrainment of ambient seawater that increases with the magnitude of ambient currents. The inertial oscillations observed in the time series provide evidence for the influence of surface storms on the dynamics of hydrothermal plumes.

  2. Evaluating the Feasibility of Acoustic Radiation Force Impulse Shear Wave Elasticity Imaging of the Uterine Cervix With an Intracavity Array: A Simulation Study

    PubMed Central

    Feltovich, Helen; Homyk, Andrew D.; Carlson, Lindsey C.; Hall, Timothy J.

    2015-01-01

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

  3. Non-contact acoustic microscopy

    Microsoft Academic Search

    Matt Clark; Steve Sharples; Mike Somekh

    2000-01-01

    We demonstrate a fast all-optical surface acoustic wave (SAW) microscope. This acoustic microscope may be thought of as a non-contact (hence non-perturbing) surface acoustic microscope. The key to producing a sufficiently high SAW amplitude for imaging without producing surface damage is to tailor the generating optical distribution. This can be used to spread the optical power on the sample surface

  4. Acoustically Bound Microfluidic Bubble Crystals

    NASA Astrophysics Data System (ADS)

    Rabaud, David; Thibault, Pierre; Mathieu, Mylène; Marmottant, Philippe

    2011-04-01

    Bubbles confined in microchannels self-organize without directly contacting one another when excited by an external acoustic field. The bubbles tend to form periodic “crystal”-like lattices with a finite interbubble distance. This equilibrium distance can be adjusted by simply tuning the acoustic frequency. This new type of crystal is purely mediated by acoustic surface waves emitted by the pulsating bubbles. Because these waves are reflected at the channel boundaries, the bubbles interact with their own images across the boundary.

  5. An In Vivo Validation of the Application of Acoustic Radiation Force to Enhance the Diagnostic Utility of Molecular Imaging Using 3D Ultrasound

    PubMed Central

    Gessner, Ryan C.; Streeter, Jason E.; Kothadia, Roshni; Feingold, Steven; Dayton, Paul A.

    2012-01-01

    For over a decade, the application of acoustic radiation force (ARF) has been proposed as a mechanism to increase ultrasonic molecular imaging (MI) sensitivity in vivo. Presented herein is the first noninvasive in vivo validation of ARF-enhanced MI with an unmodified clinical system. First, an in vitro optical-acoustical setup was used to optimize system parameters and ensure sufficient microbubble translation when exposed to ARF. 3D ARF-enhanced MI was then performed on 7 rat fibrosarcoma tumors using microbubbles targeted to ?v?3 and non-targeted microbubbles. Low-amplitude (< 25 kPa) 3D ARF pulse sequences were tested and compared to passive targeting studies in the same animal. Our results demonstrate that a 78% increase in image intensity from targeted microbubbles can be achieved when using ARF relative to the passive targeting studies. Furthermore, ARF did not significantly increase image contrast when applied to non-targeted agents, suggesting that ARF did not increase non-specific adhesion. PMID:22341052

  6. 4f4f absorption spectra and hypersensitivity in nine-coordinate Ho(III) and Er(III) complexes in different environments

    Microsoft Academic Search

    Azad A Khan; H. A Hussain; K Iftikhar

    2004-01-01

    The effect of change in the environment upon 4f4f absorption spectra of nine-coordinate Ho(III) and Er(III) complexes with thiocyanate and 2,2?-bipyridyl in methanol, DMSO, DMF and pyridine have been investigated. The oscillator strength for hypersensitive and non-hypersensitive transitions have been calculated and variation in the intensity and band shape with respect to solvent type is rationalized in terms of solvent

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

    SciTech Connect

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

    2009-08-19

    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.

  8. A complete 4f{sup n} energy level diagram for all trivalent lanthanide ions

    SciTech Connect

    Peijzel, P.S. [Department of Condensed Matter and Interfaces, Debye Institute, Utrecht University, P.O. Box 80 000, Utrecht 3508 TA (Netherlands)]. E-mail: p.s.peijzel@phys.uu.nl; Meijerink, A. [Department of Condensed Matter and Interfaces, Debye Institute, Utrecht University, P.O. Box 80 000, Utrecht 3508 TA (Netherlands); Wegh, R.T. [Department of Condensed Matter and Interfaces, Debye Institute, Utrecht University, P.O. Box 80 000, Utrecht 3508 TA (Netherlands); Reid, M.F. [Department of Physics and Astronomy, University of Canterbury, Christchurch (New Zealand); Burdick, G.W. [Department of Physics, Andrews University, Berrien Springs, MI 49104 (United States)

    2005-02-15

    We describe the calculations of the 4f{sup n} energy levels, reduced matrix elements for 4f{sup n}-4f{sup n} transitions and the simulation of absorption and emission spectra. A complete 4f{sup n} energy level diagram is calculated for all trivalent lanthanide ions in LaF{sub 3}. The calculated energy levels are compared with experimentally obtained energies. For Ce, Pr, Nd, Eu, Gd, Ho, Er, Tm and Yb many, and in some cases all, energy levels have been observed. This work provides a starting point for future investigation of as yet unobserved VUV energy levels.

  9. Acoustic Source Localization Using the Acoustic ENSBox

    E-print Network

    Grether, Gregory

    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

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

    PubMed Central

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

    2012-01-01

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

  11. Acoustic Seal

    NASA Technical Reports Server (NTRS)

    Steinetz, Bruce M. (Inventor)

    2006-01-01

    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.

  12. Acoustic seal

    NASA Technical Reports Server (NTRS)

    Steinetz, Bruce M. (Inventor)

    2006-01-01

    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.

  13. Acoustic Cavitation

    Microsoft Academic Search

    Olivier Louisnard; José González-García

    2011-01-01

    \\u000a The benefit of acoustic cavitation owes to its ability to concentrate acoustic energy in small volumes. This results in temperatures\\u000a of thousands of kelvin, pressures of GPa, local accelerations 12 orders of magnitude higher than gravity, shockwaves, and\\u000a photon emission. In a few words, it converts acoustics into extreme physics.

  14. Bioenergetic programming of macrophages by the apolipoprotein A-I mimetic peptide 4F

    PubMed Central

    Datta, Geeta; Kramer, Philip A.; Johnson, Michelle S.; Sawada, Hirotaka; Smythies, Lesley E.; Crossman, David K.; Chacko, Balu; Ballinger, Scott W.; Westbrook, David G.; Mayakonda, Palgunachari; Anantharamaiah, G. M.; Darley-Usmar, Victor M.; White, C. Roger

    2015-01-01

    The apoA-I (apolipoprotein A-I) mimetic peptide 4F favours the differentiation of human monocytes to an alternatively activated M2 phenotype. The goal of the present study was to test whether the 4F-mediated differentiation of MDMs (monocyte-derived macrophages) requires the induction of an oxidative metabolic programme. 4F treatment induced several genes in MDMs that play an important role in lipid metabolism, including PPAR? (peroxisome-proliferator-activated receptor ?) and CD36. Addition of 4F was associated with a significant increase in FA (fatty acid) uptake and oxidation compared with vehicle treatment. Mitochondrial respiration was assessed by measurement of the OCR (oxygen-consumption rate). 4F increased basal and ATP-linked OCR as well as maximal uncoupled mitochondrial respiration. These changes were associated with a significant increase in ??m (mitochondrial membrane potential). The increase in metabolic activity in 4F-treated MDMs was attenuated by etomoxir, an inhibitor of mitochondrial FA uptake. Finally, addition of the PPAR? antagonist T0070907 to 4F-treated MDMs reduced the expression of CD163 and CD36, cell-surface markers for M2 macrophages, and reduced basal and ATP-linked OCR. These results support our hypothesis that the 4F-mediated differentiation of MDMs to an anti-inflammatory phenotype is due, in part, to an increase in FA uptake and mitochondrial oxidative metabolism. PMID:25742174

  15. A multiview, multimodal fusion framework for classifying small marine animals with an opto-acoustic imaging system

    Microsoft Academic Search

    Paul L. D. Roberts; Jules S. Jaffe; Mohan M. Trivedi

    2009-01-01

    A multiview, multimodal fusion algorithm for classifying marine plankton is described and its performance is evaluated on laboratory data from live animals. The algorithm uses support vector machines with softmax outputs to classify either acoustical or optical features. Outputs from these single-view classifiers are then combined together using a feedback network with confidence weighting. For each view or modality, the

  16. Apolipoprotein A-I mimetic peptide 4F blocks sphingomyelinase-induced LDL aggregation.

    PubMed

    Nguyen, Su Duy; Javanainen, Matti; Rissanen, Sami; Zhao, Hongxia; Huusko, Jenni; Kivelä, Annukka M; Ylä-Herttuala, Seppo; Navab, Mohamad; Fogelman, Alan M; Vattulainen, Ilpo; Kovanen, Petri T; Öörni, Katariina

    2015-06-01

    Lipolytic modification of LDL particles by SMase generates LDL aggregates with a strong affinity for human arterial proteoglycans and may so enhance LDL retention in the arterial wall. Here, we evaluated the effects of apoA-I mimetic peptide 4F on structural and functional properties of the SMase-modified LDL particles. LDL particles with and without 4F were incubated with SMase, after which their aggregation, structure, and proteoglycan binding were analyzed. At a molar ratio of L-4F to apoB-100 of 2.5 to 20:1, 4F dose-dependently inhibited SMase-induced LDL aggregation. At a molar ratio of 20:1, SMase-induced aggregation was fully blocked. Binding of 4F to LDL particles inhibited SMase-induced hydrolysis of LDL by 10% and prevented SMase-induced LDL aggregation. In addition, the binding of the SMase-modified LDL particles to human aortic proteoglycans was dose-dependently inhibited by pretreating LDL with 4F. The 4F stabilized apoB-100 conformation and inhibited SMase-induced conformational changes of apoB-100. Molecular dynamic simulations showed that upon binding to protein-free LDL surface, 4F locally alters membrane order and fluidity and induces structural changes to the lipid layer. Collectively, 4F stabilizes LDL particles by preventing the SMase-induced conformational changes in apoB-100 and so blocks SMase-induced LDL aggregation and the resulting increase in LDL retention. PMID:25861792

  17. Layers and tubes of fluorographene C4F: Stability, structural and electronic properties from DFTB calculations

    NASA Astrophysics Data System (ADS)

    Enyashin, A. N.; Ivanovskii, A. L.

    2013-06-01

    By means of the DFTB band structure calculations we have explored the layers' isomerism of fluorographene C4F. The relative stability, structural and electronic properties of the C4F layers and nanotubes have been revealed depending on the possible types of fluorine coverage: single-sided, double-sided or so-called non-uniform variants. Our main finding is that the aforementioned types of fluorine coverage are crucial for the morphology of these materials. At the non-uniform or single-sided coverage types the C4F structures aspire to the spontaneous folding in order to minimize their surface tension.

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

    PubMed

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

    2014-01-01

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

  19. Imaging capability of the higher-frequency subsystem of a dual-frequency acoustic lens sonar system

    Microsoft Academic Search

    Joseph L. Lopes; Iris C. Paustian; Robert Marciniak; Dave Van Tol; Donald L. Folds

    2000-01-01

    An experimental dual-frequency acoustic lens sonar system, designed to detect both buried and non-buried objects is described with emphasis on the higher frequency subsystem. The lower frequency subsystem (35 - 100 kHz) forms conical beams with beam widths near 5 degree(s) using discrete transducer elements in the lens focal plane for both transmission and reception. The higher frequency (1 -

  20. Topological Acoustics

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  2. Acoustic-emission linear-pulse holography

    SciTech Connect

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

    1982-06-01

    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.

  3. 48 CFR 47.305-4 - F.o.b. destination solicitations.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 2014-10-01 2014-10-01 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...

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

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 2013-10-01 2013-10-01 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...

  5. 48 CFR 47.305-4 - F.o.b. destination solicitations.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 2012-10-01 2012-10-01 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...

  6. 48 CFR 47.305-4 - F.o.b. destination solicitations.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 2011-10-01 2011-10-01 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...

  7. 48 CFR 47.305-4 - F.o.b. destination solicitations.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 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...

  8. FISH detection of Wolf-Hirschhorn syndrome: Exclusion of D4F26 as critical site

    SciTech Connect

    Johnson, V.P.; Altherr, M.R.; Blake, J.M.; Keppen, L.D.

    1994-08-01

    Wolf-Hirschhorn syndrome (WHS) is due to a deletion in the terminal band of 4p16.3. Among loci that have been involved in deletions are D4S95, D4S125, D4F26, as shown by PCR typing, Southern blot hybridization, and/or fluorescent in situ hybridization (FISH). Currently, FISH detection of WHS is predicated upon the deletion of the D4F26 locus with failure to hybridize to pC847.351, a commercially available cosmid probe. A WHS patient is shown to have an interstitial deletion, by hemizygosity at D4S98 and D4F26. This suggests that the tip of 4p, specifically D4F26, is not a critical deletion site for WHS. 19 refs., 4 figs.

  9. Web Ecology: Recycling HTML Pages as XML Documents Using W4F

    Microsoft Academic Search

    Arnaud Sahuguet; Fabien Azavant

    1999-01-01

    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

  10. Translation initiation factor eIF4F modifies the dexamethasone response in multiple myeloma

    PubMed Central

    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

    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

  11. 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)

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

    2015-02-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2011-02-01

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

  13. Acoustic emission

    NASA Astrophysics Data System (ADS)

    Asty, M.

    1983-01-01

    A review of acoustic emission methods is presented. These are considered to be a valuable nondestructive technique to evaluate the effect of stresses on materials. The nature of acoustic emissions are described. Techniques which are most suited to industrial applications are emphasized. Codification attempts by ASME and ASTM are discussed.

  14. Resolution Improvement of Scanning Acoustic Microscopy Using Sparse Signal Representation

    Microsoft Academic Search

    Raheleh Mohammadi; Ali Mahloojifar

    2009-01-01

    Scanning acoustic microscopy is an imaging method in which the focused high frequency ultrasound is used to visualize the\\u000a micro structures. The morphology and acoustic properties of the biological tissues can be evaluated using scanning acoustic\\u000a microscope system. To determine thin tissues having micrometer thickness, the high acoustic frequency is required for conventional\\u000a SAM. In practice the acoustic frequency is

  15. P4F-6 On the Potential of Combined ARFI and Elastography to Improve Differentiation of Material Structure in Viscoelastic Tissue

    Microsoft Academic Search

    F. William Mauldin; Olgha B. Davis; Mansoor A. Haider; Elizabeth G. Loboa; T. Wayne Pfeiler; Caterina M. Gallippi

    2007-01-01

    Acoustic radiation force imaging methods distinguish tissue structure and composition by monitoring tissue responses to applied radiation force excitations. Applying Voigt and Kelvin viscoelastic tissue models, we present a new radiation force technique - monitored steady-state excitation and recovery (MSSER) imaging - that tracks both steady-state displacement during prolonged force application and transient response following force cessation to estimate tissue

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

    E-print Network

    Abraham, Nader G.

    -treated, ob, ob-L-4F-treated, and ob- L-4F-LY294002. Food intake, insulin, glucose adipocyte stem cells, p hypoth- esized that L-4F reduces adiposity via increased pAMPK, pAKT, HO-1, and increased insulin adipose tissue (VAT) were determined by MRI and hepatic lipid content by magnetic resonance spectroscopy

  17. Acoustic measurement of the Deepwater Horizon Macondo well flow rate

    E-print Network

    Camilli, Richard

    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 ...

  18. 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

    Story, Brad H.

    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

  19. Acoustic emission linear pulse holography

    SciTech Connect

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

    1985-07-30

    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.

  20. Acoustic emission linear pulse holography

    DOEpatents

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

    1985-01-01

    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.

  1. 2688 IEEE TRANSACTIONS ON PLASMA SCIENCE, VOL. 42, NO. 10, OCTOBER 2014 Imaging of the Dust Acoustic Wave

    E-print Network

    Goree, John

    glow discharge plasma was ignited by applying a 13.56-MHz radio frequency voltage with 57 V peak by planar laser-light scattering. Space­time diagrams based on the images reveal how the nonlinearity have such a high amplitude, and they propagate so slowly, that they are easy to view and image by laser

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

    Microsoft Academic Search

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

    2009-01-01

    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

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

    NASA Astrophysics Data System (ADS)

    Stepanishen, Peter R.; Brodjonegoro, Irsan

    2002-11-01

    An inverse or backward projection method based on a combined Greens function and singular value decomposition method is developed to locate and to determine the strength of near field harmonic sources from the acoustic field on the surface of a nearby rigid body. A resolution matrix, which is based on the free space Greens function, the geometry of the measurement surface of interest and the field locations of interest, is introduced to determine the resolution and accuracy of the backward projection method. Point source distributions located above a rigid planar surface are addressed both analytically and numerically. In addition, line source distributions located outside of infinite rigid circular and elliptical cylinders are also addressed. It is demonstrated that the method is able to identify the location and to determine the strength of harmonic near-field sources which are separated by less than 0.01 of a wavelength.

  4. Plasma diagnostic potential of 2p4f in N$^+$ -- accurate wavelengths and oscillator strengths

    E-print Network

    Shen, Xiaozhi; Jönsson, Per; Wang, Jianguo

    2015-01-01

    Radiative emission lines from nitrogen and its ions are often observed in nebulae spectra, where the N$^{2+}$ 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 (MCDHF) 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 w...

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

    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.

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

    PubMed

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

    2012-08-01

    Myeloperoxidase (MPO)-derived hypochlorous acid induces changes in HDL function via redox modifications at the level of apolipoprotein A-I (apoA-I). As 4F and apoA-I share structural and functional properties, we tested the hypothesis that 4F acts as a reactive substrate for hypochlorous acid (HOCl). 4F reduced the HOCl-mediated oxidation of the fluorescent substrate APF in a concentration-dependent manner (ED(50) ? 56 ± 3 ?M). This reaction induced changes in the physical properties of 4F. Addition of HOCl to 4F at molar ratios ranging from 1:1 to 3:1 reduced 4F band intensity on SDS-PAGE gels and was accompanied by the formation of a higher molecular weight species. Chromatographic studies showed a reduction in 4F peak area with increasing HOCl and the formation of new products. Mass spectral analyses of collected fractions revealed oxidation of the sole tryptophan (Trp) residue in 4F. 4F was equally susceptible to oxidation in the lipid-free and lipid-bound states. To determine whether Trp oxidation influenced its apoA-I mimetic properties, we monitored effects of HOCl on 4F-mediated lipid binding and ABCA1-dependent cholesterol efflux. Neither property was altered by HOCl. These results suggest that 4F serves as a reactive substrate for HOCl, an antioxidant response that does not influence the lipid binding and cholesterol effluxing capacities of the peptide. PMID:22589558

  7. Luminescence in Li2Sr2Al2PO4F9:Dy3+ - a novel nanophosphor.

    PubMed

    Shinde, K N; Dhoble, S J

    2012-01-01

    Earlier research has revealed numerous advantages of the wet chemical method in reaction acceleration, yield improvement, enhanced photoluminescence properties and the evolution of new material phases. In the present study the novel nanophosphor Li(2)Sr(2)Al(2)PO(4)F(9):Dy(3+) was synthesized by a one-step wet chemical method. Formation of single-phase compounds was confirmed by X-ray diffraction (XRD) and characterized by photoluminescence (PL) and transmission electron microscopy (TEM) techniques. The average diameter of the particles was calculated from the TEM image as ca. 20?nm. The synthesized nanophosphor exhibited intense blue and yellow emissions at 482 and 575?nm, respectively, owing to the Dy(3+) ion, by Hg-free excitation at 387?nm, i.e. solid-state lighting excitation. The results obtained showed that phosphors have the potential for applications in the lamp industry. PMID:21656650

  8. The acoustic lens design and in vivo use of a multifunctional catheter combining intracardiac ultrasound imaging and electrophysiology sensing

    Microsoft Academic Search

    Douglas N. Stephens; Jonathan Cannata; Ruibin Liu; Jian Zhong Zhao; K. K. Shung; Hien Nguyen; R. Chia; A. Dentinger; D. Wildes; K. E. Thomenius; A. Mahajan; K. Shivkumar; Kang Kim; M. O'Donnell; David Sahn

    2008-01-01

    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

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

    Microsoft Academic Search

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

    1990-01-01

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

  10. Optimization of Contrast-to-Tissue Ratio Through Pulse Windowing in Dual-Frequency "Acoustic Angiography" Imaging.

    PubMed

    Lindsey, Brooks D; Shelton, Sarah E; Dayton, Paul A

    2015-07-01

    Early-stage tumors in many cancers are characterized by vascular remodeling, indicative of transformations in cell function. We have previously presented a high-resolution ultrasound imaging approach to detecting these changes that is based on microbubble contrast agents. In this technique, images are formed from only the higher harmonics of microbubble contrast agents, producing images of vasculature alone with 100- to 200-?m resolution. In this study, shaped transmit pulses were used to image the higher broadband harmonic echoes of microbubble contrast agents, and the effects of varying pulse window and phasing on microbubble and tissue harmonic echoes were evaluated using a dual-frequency transducer in vitro and in vivo. An increase in the contrast-to-tissue ratio of 6.8 ± 2.3 dB was observed in vitro using an inverted pulse with a cosine window relative to a non-inverted pulse with a rectangular window. The increase in mean image intensity resulting from contrast enhancement in vivo in five rodents was 13.9 ± 3.0 dB greater for an inverted cosine-windowed pulse and 17.8 ± 3.6 dB greater for a non-inverted Gaussian-windowed pulse relative to a non-inverted pulse with a rectangular window. Implications for pre-clinical and diagnostic imaging are discussed. PMID:25819467

  11. Valency and 4f covalency of Cs2RbTbF7

    NASA Astrophysics Data System (ADS)

    Hu, Z.; Cho, En-Jin; Kaindl, G.; Müller, B. G.

    1995-03-01

    Valency and 4f covalency of Cs2RbTbF7 were studied by x-ray-absorption near-edge-structure (XANES) spectroscopy at the Tb-LI-III, Tb-MIV,V, and F-K absorption thresholds as well as by 3d core-level photoemission (3d-PE). The availability of a chemically pure and stable sample allowed the observation of solely intrinsic spectral features in the core-level spectra, which characterize Cs2RbTbF7 as the tetravalent lanthanide compound with the weakest 4f-ligand hybridization known. Both the Tb final-state spectra, analyzed on the basis of a simplified Anderson single-impurity model, and the F-K XANES spectrum provide insight into 4f-ligand-p mixing in this compound.

  12. SF6 and C4F8 global kinetic models coupled to sheath models

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    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.

  13. Kondo-like 4f delocalization in Gd at high pressure

    SciTech Connect

    Maddox, B R; Lazicki, A; Yoo, C S; Iota, V; Chen, M; McMahan, A K; Hu, M Y; Chow, P; Scalettar, R T; Pickett, W E

    2005-11-28

    We present resonant inelastic x-ray scattering (RIXS) and x-ray emission spectroscopy (XES) results which suggest Kondo-like aspects in the delocalization of 4f electrons in Gd metal to 113 GPa. Analysis of the RIXS data reveal a prolonged and continuous process throughout the entire pressure range, so that the volume collapse transition at 59 GPa is only part of the delocalization phenomenon. Moreover, the L{sub {gamma}1} XES spectra indicate no apparent change in the bare 4f moment across the collapse, suggesting that Kondo screening is responsible for the expected Pauli-like behavior in magnetic susceptibility.

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

    PubMed Central

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

    2011-01-01

    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

  15. Regulation of POU4F3 gene expression in hair cells by 5' DNA in mice.

    PubMed

    Masuda, M; Dulon, D; Pak, K; Mullen, L M; Li, Y; Erkman, L; Ryan, A F

    2011-12-01

    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 basic helix-loop-helix (bHLH) transcription factors, including motifs activated by ATOH1. Cotransfection of HEK293 or VOT-E36 cells with ATOH1 and the transgene as a reporter enhanced eGFP expression when compared with 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

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

    Microsoft Academic Search

    Masatsugu Fukunaga; Takayuki Goto; Kazuya Miyagawa; Tetsuo Fukase

    1994-01-01

    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.

  17. Precision calculations for H -> WW/ZZ -> 4fermions with PROPHECY4f

    E-print Network

    A. Bredenstein; A. Denner; S. Dittmaier; M. M. Weber

    2007-08-30

    PROPHECY4f is a Monte Carlo event generator for precise simulations of the Higgs-boson decay H -> WW/ZZ -> 4fermions, supporting leptonic, semileptonic, and four-quark final states. Both electroweak and QCD corrections are included. Treating the intermediate gauge bosons as resonances, the calculation covers the full Higgs-boson mass range above, near, and below the gauge-boson pair thresholds. In this article we pay particular attention to the recently implemented option of PROPHECY4f to generate unweighted events.

  18. Characterization of polymer formation during SiO2 etching with different fluorocarbon gases (CHF3, CF4, C4F8)

    NASA Astrophysics Data System (ADS)

    Loong, Sang Y.; Lee, H. P.; Chan, Lap Hung; Zhou, Mei-Sheng; Loh, F. C.; Tan, K. L.

    1997-08-01

    In this paper, the polymer composition generated by three different combinations of gas chemistries for oxide etch are studied and the effects of different O2 plasma strip duration on polymer removal are also presented. The etch chemistries used were CHF3/CF4, CO/CF4/CHF3 and C4F8/CO/CHF3 chemistry. From the x-ray photoelectron spectroscopy (XPS) C 1s spectra, five distinct peaks are identified which correspond to C-C, C-CFx, CF, CF2, and CF3. The C/F ratio is found to be highest for polymer generated by the C4F8/CO/CHF3 chemistry, about 0.8, whereas the C/F ratios for those by CHF3/CF4 and CO/CF4/CHF3 chemistries are about 0.6. Atomic force microscopy (AFM) images show that the polymer generated by the C4F8/CO/CHF3 chemistry is much rougher than that by CHF3/CF4 and CO/CF4/CHF3 chemistries. The XPS spectra of C 1s also show a significant decrease in the intensity of the more fluorinated carbon peaks (CF3 and CF2) after O2 plasma strip. The C/F ratios increased to about 1.4 to 1.8 after O2 plasma strip. The spectra are similar for different O2 strip times, indicating the decrease is independent of O2 strip duration. From the AFM images, all the polymers formed by CHF3/CF4 and CO/CF4/CHF3 chemistries are rather smooth with no visible change after O2 strip. However, the polymers generated by C4F8/CO/CHF3 chemistry are flattened with increasing O2 strip duration. The high energy ion bombardment of oxygen ions probably have flattened the rough polymer surface.

  19. External Flow of an Acoustically Levitated Droplet

    Microsoft Academic Search

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

    2008-01-01

    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

  20. Acoustic Inversion in Optoacoustic Tomography: A Review

    PubMed Central

    Rosenthal, Amir; Ntziachristos, Vasilis; Razansky, Daniel

    2013-01-01

    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

  1. Acoustic Inversion in Optoacoustic Tomography: A Review.

    PubMed

    Rosenthal, Amir; Ntziachristos, Vasilis; Razansky, Daniel

    2013-11-01

    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

  2. Characterization of a broadband all-optical ultrasound transducer-from optical and acoustical properties to imaging

    Microsoft Academic Search

    Yang Hou; Jin-sung Kim; Sheng-wen Huang; Shai Ashkenazi; L. J. Guo; M. O'Donnell

    2008-01-01

    A broadband all-optical ultrasound transducer has been designed, fabricated, and evaluated for high- frequency ultrasound imaging. The device consists of a 2-D gold nanostructure imprinted on top of a glass substrate, followed by a 3 mum PDMS layer and a 30 nm gold layer. A laser pulse at the resonance wavelength of the gold nanostructure is focused onto the surface

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

    Microsoft Academic Search

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

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

  4. 4F13: Machine Learning Lectures 1-2: Introduction to Machine Learning

    E-print Network

    Ghahramani, Zoubin

    4F13: Machine Learning Lectures 1-2: Introduction to Machine Learning Zoubin Ghahramani zoubin@eng.cam.ac.uk Department of Engineering University of Cambridge Michaelmas, 2006 http://learning.eng.cam.ac.uk/zoubin/ml06 Processing--but don't despair, a lot of new material later! #12;What is machine learning useful for? #12

  5. Energy position of 4f levels in rare-earth metals

    Microsoft Academic Search

    Börje Johansson

    1979-01-01

    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

  6. 48 CFR 47.303-4 - F.o.b. origin, freight prepaid.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...2013-10-01 2013-10-01 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...

  7. 48 CFR 47.303-4 - F.o.b. origin, freight prepaid.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...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...

  8. 48 CFR 47.303-4 - F.o.b. origin, freight prepaid.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...2012-10-01 2012-10-01 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...

  9. 48 CFR 47.303-4 - F.o.b. origin, freight prepaid.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...2011-10-01 2011-10-01 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...

  10. 48 CFR 47.303-4 - F.o.b. origin, freight prepaid.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...2014-10-01 2014-10-01 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...

  11. Radiative corrections to e+e- --> WW --> 4f with RACOONWW

    E-print Network

    A. Denner; S. Dittmaier; M. Roth; D. Wackeroth

    2000-06-27

    RACOONWW is the first Monte Carlo generator for e+e- --> WW --> 4f(+gamma) that includes the electroweak O(alpha) radiative corrections in the double-pole approximation completely. Some numerical results for LEP2 energies are discussed, and the predictions for the total W-pair cross section are confronted with LEP2 data.

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

    E-print Network

    Abraham, Nader G.

    bone marrow (P , 0.039) and in cultures of human bone marrow-derived mesenchy- mal stem cells (P , 0 are associated with an inflammatory response in these cells. Adipose tissue plays an important role in insulinL-4F treatment reduces adiposity, increases adiponectin levels, and improves insulin sensitivity

  13. Clinical Characterization of Genetic Hearing Loss Caused by a Mutation in the POU4F3

    E-print Network

    Avraham, Karen

    that these discoveries will herald new treat- ments for deafness. More than half of cases of deafness are due to geneticClinical Characterization of Genetic Hearing Loss Caused by a Mutation in the POU4F3 Transcription B. Avraham, PhD Objectives: To describe the detailed auditory pheno- type of DFNA15, genetic hearing

  14. CYP4F2 genetic polymorphisms are associated with coronary heart disease in a Chinese population

    PubMed Central

    2014-01-01

    Background To explore the relationship between CYP4F2 gene polymorphism and coronary heart disease (CHD) in a Chinese Han population. Methods We selected 440 CHD patients and 440 control subjects to perform a case - control study. Four SNPs (rs2108622, rs3093100, rs3093105 and rs3093135) in CYP4F2 gene were genotyped using polymerase chain reaction - restriction fragment length polymorphism (PCR - RFLP) methods. The genotype and haplotype distributions were compared between the case and the control group. Results We found both rs2108622 and rs3093105 in CYP4F2 gene were associated with the risk for CHD (P <0.01). Haplotype analysis indicated that GGGT haplotype consisted by rs2108622-rs3093100-rs3093105-rs3093135 was associated with CHD risk (OR?=?4.367, 95% CI: 2.241?~?8.510; P?4F2 gene polymorphisms were associated with the risk of CHD in Chinese population. PMID:24886380

  15. Acoustic Characterization of Mesoscale Objects

    SciTech Connect

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

    2007-03-13

    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.

  16. 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)

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

    2014-12-01

    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.

  17. The use of broadband acoustic transducers and pulse-compression techniques for air-coupled ultrasonic imaging

    Microsoft Academic Search

    T. H. Gan; D. A. Hutchins; D. R. Billson; D. W. Schindel

    2001-01-01

    A pulse-compression technique has been applied to air-coupled testing of solid materials. Capacitance transducers were used to generate wide bandwidth swept-frequency (chirp) signals in air, which were then used to measure and image solid samples in through transmission. The results demonstrate that such signal processing techniques lead to an improvement in the signal to noise ratio and timing accuracy for

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

    NASA Astrophysics Data System (ADS)

    Shaw, John M.

    2013-06-01

    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!

  19. 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)

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

    2010-01-01

    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.

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

    NASA Technical Reports Server (NTRS)

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

    2009-01-01

    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

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

    PubMed

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

    2014-07-01

    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

  2. Quantitative Thermo-acoustics and related problems Guillaume Bal

    E-print Network

    Bal, Guillaume

    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

  3. 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

  4. Quantitative Thermo-acoustics and related problems Guillaume Bal

    E-print Network

    Ren, Kui

    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

  5. Robotic vehicle uses acoustic sensors for voice detection and diagnostics

    Microsoft Academic Search

    Stuart H. Young; Michael V. Scanlon

    2000-01-01

    An acoustic sensor array that cues an imaging system on a small tele- operated robotic vehicle was used to detect human voice and activity inside a building. The advantage of acoustic sensors is that it is a non-line of sight (NLOS) sensing technology that can augment traditional LOS sensors such as visible and IR cameras. Acoustic energy emitted from a

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

    E-print Network

    Truszczynski, Miroslaw

    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

  7. Acoustic Simulation COMP 768 Presentation

    E-print Network

    North Carolina at Chapel Hill, University of

    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

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

    Microsoft Academic Search

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

    2002-01-01

    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

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

    NASA Astrophysics Data System (ADS)

    Hughes Clarke, J. E.

    2013-12-01

    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.

  10. http://grantsandcontracts.wustl.edu/medadmin/gcsite.nsf/3d4f63e96e9ef2b586256d4f0053d4f5/ff34cd20bed744868625703500579dc6/$FILE/What to Submit to OSRS Grant Team -Electronic Applications.doc Created 5/3/05; Updated 1/11/13

    E-print Network

    Subramanian, Venkat

    http://grantsandcontracts.wustl.edu/medadmin/gcsite.nsf/3d4f63e96e9ef2b586256d4f0053d4f5/ff34cd20 Personnel Report (Commons ID is required for PD/PIs and Postdoc roles) NSF/FASTLANE Cover page Budget APPLICATION Plus Budget justification Plus Other Support Signed by Department Chair NON-NIH/NSF GRANTS

  11. Acoustic crystals

    Microsoft Academic Search

    A. A. Blistanov; V. S. Bondarenko; N. V. Perelomova; F. N. Strizhevskaia; V. V. Chkalova; M. P. Shaskolskaia

    1982-01-01

    This handbook contains material on the main physical properties of the crystals most often used in acoustics and acoustoelectronics. The data presented are from 1300 published works by investigators from the USSR and other countries. The works deal with the structure, physicochemical properties, and optical, electrooptical, and piezoelectric parameters of 78 crystals. They also treat the elastic constants and the

  12. Observation of cavitation bubbles and acoustic streaming in high intensity ultrasound fields

    NASA Astrophysics Data System (ADS)

    Uemura, Yuuki; Sasaki, Kazuma; Minami, Kyohei; Sato, Toshio; Choi, Pak-Kon; Takeuchi, Shinichi

    2015-07-01

    We observed the behavior of acoustic cavitation by sonochemical luminescence and ultrasound B-mode imaging with ultrasound diagnostic equipment in a standing-wave ultrasound field and focused ultrasound field. Furthermore, in order to investigate the influence of acoustic streaming on acoustic cavitation bubbles, we performed flow analysis of the sound field using particle image velocimetry. We found that acoustic cavitation bubbles are stirred by circulating acoustic streaming and local vortexes occurring in the water tank of the standing-wave ultrasound exposure system. We considered that the acoustic cavitation bubbles are carried away by acoustic streaming due to the high ultrasound pressure in the focused ultrasound field.

  13. Investigations on Pva:. NH4F: ZrO2 Composite Polymer Electrolytes

    NASA Astrophysics Data System (ADS)

    Radha, K. P.; Selvasekarapandian, S.; Karthikeyan, S.; Sanjeeviraja, C.

    2013-07-01

    Composite polymer electrolytes have been prepared using Poly (vinyl alcohol), ammonium fluoride, nanofiller ZrO2 by solution casting technique. The amorphous nature of the composite polymer electrolyte has been confirmed by XRD analysis. FTIR analysis confirms the complex formation among the polymer, salt and nanofiller. The maximum ionic conductivity for 85 PVA:15 NH4F has been found to be 6.9 × 10-6 Scm-1 at ambient temperature. In the present work, the addition of 2 mol% nanofilller ZrO2 to the electrolyte 85PVA:15NH4F enhances the conductivity to 3.4 × 10-5 Scm-1. The temperature dependence of the conductivity of composite polymer electrolytes obeys Arrhenius relation. In the modulus spectra, there is a long tail at low frequencies which is an evidence for large capacitance associated with the electrodes. In the high frequency region, ?'(?) value saturates and giving rise to the dielectric constant of the material.

  14. Acoustic transducer for acoustic microscopy

    DOEpatents

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

    1990-03-20

    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.

  15. Acoustic transducer for acoustic microscopy

    DOEpatents

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

    1990-01-01

    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.

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

    E-print Network

    Boyer, Edmond

    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

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

    SciTech Connect

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

    2008-09-11

    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.

  18. Long-term tropospheric trend of octafluorocyclobutane (c-C4F8 or PFC-318)

    NASA Astrophysics Data System (ADS)

    Oram, D. E.; Mani, F. S.; Laube, J. C.; Newland, M. J.; Reeves, C. E.; Sturges, W. T.; Penkett, S. A.; Brenninkmeijer, C. A. M.; Röckmann, T.; Fraser, P. J.

    2011-07-01

    Air samples collected at Cape Grim, Tasmania between 1978 and 2008 and during a series of more recent aircraft sampling programmes have been analysed to determine the atmospheric abundance and trend of octafluorocyclobutane (-C4F8 or PFC-318). c-C4F8 has an atmospheric lifetime in excess of 3000 yr and a global warming potential (GWP) of 10 300 (100 yr time horizon), making it one of the most potent greenhouse gases detected in the atmosphere to date. The abundance of c-C4F8 in the Southern Hemisphere has risen from 0.35 ppt in 1978 to 1.2 ppt in 2010, and is currently increasing at a rate of around 0.03 ppt yr-1. It is the third most abundant perfluorocarbon (PFC) in the present day atmosphere, behind CF4 (~75 ppt) and C2F6 (~4 ppt). The origin of c-C4F8 is unclear. Using a 2-D global model to derive top-down global emissions based on the Cape Grim measurements yields a recent (2007) emission rate of around 1.1 Gg yr-1 and a cumulative emission up to and including 2007 of 38.1 Gg. Emissions reported on the EDGAR emissions database for the period 1986-2005 represent less than 1 % of the top-down emissions for the same period, which suggests there is a large unaccounted for source of this compound. It is also apparent that the magnitude of this source has varied considerably over the past 30 yr, declining sharply in the late 1980s before increasing again in the mid-1990s.

  19. Long-term tropospheric trend of octafluorocyclobutane (c-C4F8 or PFC-318)

    NASA Astrophysics Data System (ADS)

    Oram, D. E.; Mani, F. S.; Laube, J. C.; Newland, M. J.; Reeves, C. E.; Sturges, W. T.; Penkett, S. A.; Brenninkmeijer, C. A. M.; Röckmann, T.; Fraser, P. J.

    2012-01-01

    Air samples collected at Cape Grim, Tasmania between 1978 and 2008 and during a series of more recent aircraft sampling programmes have been analysed to determine the atmospheric abundance and trend of octafluorocyclobutane (c-C4F8 or PFC-318). c-C4F8 has an atmospheric lifetime in excess of 3000 yr and a global warming potential (GWP) of 10 300 (100 yr time horizon), making it one of the most potent greenhouse gases detected in the atmosphere to date. The abundance of c-C4F8 in the Southern Hemisphere has risen from 0.35 ppt in 1978 to 1.2 ppt in 2010, and is currently increasing at a rate of around 0.03 ppt yr-1. It is the third most abundant perfluorocarbon (PFC) in the present day atmosphere, behind CF4 (~75 ppt) and C2F6 (~4 ppt). Although a number of potential sources of c-C4F8 have been reported, including the electronics and semi-conductor industries, there remains a large discrepancy in the atmospheric budget. Using a 2-D global model to derive top-down global emissions based on the Cape Grim measurements yields a recent (2007) emission rate of around 1.1 Gg yr-1 and a cumulative emission up to and including 2007 of 38.1 Gg. Emissions reported on the EDGAR emissions database for the period 1986-2005 represent less than 1% of the top-down emissions for the same period, which suggests there is a large unaccounted for source of this compound. It is also apparent that the magnitude of this source has varied considerably over the past 30 yr, declining sharply in the late 1980s before increasing again in the mid-1990s.

  20. The 4f multipole ordering effect on core-level spectroscopies of Ce intermetallics

    NASA Astrophysics Data System (ADS)

    Sasabe, Norimasa; Tonai, Hironori; Uozumi, Takayuki

    2015-03-01

    The 3d transition metal compounds and 4f rare earth compounds show attractive phenomena, such as superconductivity and Kondo effect, due to strong electron correlations among localized 3d and 4f electrons. Especially, multipole ordering of orbital and/or spin in 4f and 5f compounds is attracting much attention these years. For example, CeB6 is known to show antiferro-quadrupolar (AFQ) ordering below 3.2K. X-ray core-level spectroscopy is an efficient technique to investigate the electronic states of strongly correlated systems. Recent years, experimental techniques have been rapidly developing and, especially, the progress in experimental resolution has enabled us to observe fine spectral features, which were not formerly observed. These advantages will enable us to observe spectral fine features related with the multipole ordering. In this study, we discuss multipole ordering effects on X-ray spectra for CeB6, especially paying attention on the polarization dependence. In order to simulate the electronic state of CeB6 with the multipole ordering, we use an impurity Anderson model including a simplified RKKY interaction.

  1. Q-switched Nd lasers pumped directly into the 4F 3/2 emitting level

    NASA Astrophysics Data System (ADS)

    Pavel, N.; Dascalu, T.; Salamu, G.; Sandu, O.; Leca, A.; Lupei, V.

    2009-12-01

    The influence of the direct pumping into the 4F 3/2 emitting level on the output characteristics of continuous-wave (CW) pumped, passively or actively (acoustooptic, AO) Q-switched Nd lasers is discussed. In case of passive Q-switching by Cr 4+:YAG saturable absorber (SA) crystal, the change of pumping wavelength from 0.81 ?m into the highly-absorbing 4F 5/2 level to 0.88 ?m into the 4F 3/2 level of Nd does not modify the energy of the Q-switch pulse, but increases the pulse repetition rate and the laser average power for the same absorbed pump power. This is demonstrated with 0.81 and 0.88 ?m CW laser diode-pumped Nd:YAG and Nd-vanadate lasers with average output power in the watt-level range at 1.06 ?m. The effect is explained by the control of passive Q-switching by the intracavity photon flux that is influenced by the pump wavelength and by the initial transmission of the SA crystal. On the other hand, it is discussed and experimentally proved that due to the possibility to control externally the frequency of switching, in case of the AO Q-switched Nd laser the change of the pump wavelength from 0.81 to 0.88 ?m increases the pulse energy for a fixed frequency, leading to a corresponding increase of the average laser power.

  2. High-Resolution Acoustic Imaging in the Agadir-Canyon Region, NW-Africa: Morphology, Processes and Geohazards

    NASA Astrophysics Data System (ADS)

    Krastel, S.; Wynn, R. B.; Feldens, P.; Unverricht, D.; Huehnerbach, V.; Stevenson, C.; Glogowski, S.; Schuerer, A.

    2014-12-01

    Agadir Canyon is one of the largest submarine canyons in the World, supplying giant submarine sediment gravity flows to the Agadir Basin and the wider Moroccan Turbidite System. While the Moroccan Turbidite System is extremely well investigated, almost no data from the source region, i.e. the Agadir Canyon, are available. Understanding why some submarine landslides remain as coherent blocks of sediment throughout their passage downslope, while others mix and disintegrate almost immediately after initial failure, is a major scientific challenge, which was addressed in the Agadir Canyon source region during Cruise MSM32. We collected ~ 1500 km of high-resolution seismic 2D-lines in combination with a dense net of hydroacoustic data. About 1000 km2 of sea floor were imaged during three deployments of TOBI (deep-towed sidescan sonar operated by the National Oceanography Centre Southampton). A total of 186 m of gravity cores and several giant box cores were recovered at more than 50 stations. The new data show that Agadir canyon is the source area of the world's largest submarine sediment flow, which occurred about 60,000 years ago. Up to 160 km3 of sediment was transported to the deep ocean in a single catastrophic event. For the first time, sediment flows of this scale have been tracked along their entire flow pathway. A major landslide area was identified south of Agadir Canyon. Landslide material enters Agadir canyon in about 2500 m water depth; the material is transported as debrite for at least another 200 km down the canyon. Initial data suggest that the last major slide from this source entered Agadir canyon at least 130,000 years ago. A large field of living deep-water corals was imaged north of Agadir canyon. To our knowledge, these are the first living cold water corals recovered off the coast of Morocco (except for the Gulf of Cadiz). They represent an important link between the known cold-water coral provinces off Mauritania and in the Gulf of Cádiz.

  3. 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

    Ravicz, Michael E.; Melcher, Jennifer R.

    2007-01-01

    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

  4. Air-coupled acoustic thermography for in-situ evaluation

    NASA Technical Reports Server (NTRS)

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

    2010-01-01

    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.

  5. Time-series observations of hydrothermal discharge using an acoustic imaging sonar: a NEPTUNE observatory case study

    NASA Astrophysics Data System (ADS)

    Xu, Guangyu; Bemis, Karen; Jackson, Darrell; Light, Russ

    2015-04-01

    One intriguing feature of a mid-ocean ridge hydrothermal system is the intimate interconnections among hydrothermal, geological, oceanic, and biological processes. The advent of the NEPTUNE observatory operated by Ocean Networks Canada at the Endeavour Segment, Juan de Fuca Ridge enables scientists to study these interconnections through multidisciplinary, continuous, real-time observations. In this study, we present the time-series observations of a seafloor hydrothermal vent made using the Cabled Observatory Vent Imaging Sonar (COVIS). COVIS is currently connected to the NEPTUNE observatory to monitor the hydrothermal discharge from the Grotto mound on the Endeavour Segment. Since its deployment in 2010, COVIS has recorded a 3-year long dataset of the shape and outflow fluxes of the buoyant plumes above Grotto along with the areal coverage of its diffuse flow discharge. The interpretation of these data in light of contemporaneous observations of ocean currents, venting temperature, and seismicity made using other NEPTUNE observatory instruments reveals significant impacts of ocean currents and geological events on hydrothermal venting. In this study, we summarize these findings in the hope of forming a more complete understanding of the intricate interconnections among oceanic, geological, and hydrothermal processes.

  6. Acoustic chaos

    SciTech Connect

    Lauterborn, W.; Parlitz, U. [Drittes Physikalisches Institut, Universitaet Goettingen, D-37073 Goettingen (Germany); Holzfuss, J.; Billo, A. [Institut fuer Angewandte Physik, Technische Hochschule Darmstadt, D-64289 Darmstadt (Germany); Akhatov, I. [Department of Continuous Media Mechanics, Bashkir State University, Ufa 450074 (Russia)

    1996-06-01

    Acoustic cavitation, a complex, spatio-temporal dynamical system, is investigated with respect to its chaotic properties. The sound output, the {open_quote}{open_quote}noise{close_quote}{close_quote}, is subjected to time series analysis. The spatial dynamics of the bubble filaments is captured by high speed holographic cinematography and subsequent digital picture processing from the holograms. Theoretical models are put forward for describing the pattern formation. {copyright} {ital 1996 American Institute of Physics.}

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

    NASA Astrophysics Data System (ADS)

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

    2013-03-01

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

  8. Anisotropic Metamaterials for Full Control of Acoustic Waves

    NASA Astrophysics Data System (ADS)

    Christensen, Johan; de Abajo, F. Javier García

    2012-03-01

    We study a class of acoustic metamaterials formed by layers of perforated plates and producing negative refraction and backward propagation of sound. A slab of such material is shown to act as a perfect acoustic lens, yielding images with subwavelength resolution over large distances. Our study constitutes a nontrivial extension of similar concepts from optics to acoustics, capable of sustaining negative refraction over extended angular ranges, with potential application to enhanced imaging for medical and detection purposes, acoustofluidics, and sonochemistry.

  9. LOCAPHONY - NEW ACOUSTICAL METHOD OF EXPRESS FUNCTIONAL MEDICINE DIAGNOSTICS

    Microsoft Academic Search

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

    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

  10. Heat capacity of RFexMn12-x (R = Gd, Tb and Dy) compounds: wiping out a cooperative 4f 4f exchange interaction by breaking the 3d 4f magnetic symmetry

    NASA Astrophysics Data System (ADS)

    Piqué, C.; Blanco, J. A.; Burriel, R.; Abad, E.; Fernández-Rodríguez, J.; Artigas, M.

    2008-08-01

    Using adiabatic calorimetry the heat capacity of a series of RFexMn12-x (R = Gd, Tb and Dy) compounds has been measured from 3 to 350 K. The substitution of Fe for Mn in RFexMn12-x influences both the magnetic interactions on the 3d sublattice and the magnetism of R (the Néel temperature doubles on going from x = 0 to 6 and the compounds become ferromagnetic for x = 8 with Curie temperatures of around 300 K). In pure TbMn12 the heat-capacity data shows a ?-type anomaly associated with the independent cooperative magnetic ordering of the R sublattice (~5 K), while the anomaly related to the Mn magnetic ordering (~100 K) is rather smooth, as observed in other itinerant magnetic systems such as YMn12. In contrast, the substitution of Fe for Mn leads, on the one hand, to a more localized magnetic behaviour of the 3d sublattice, and, on the other, to magnetic polarization effects between the 3d and 4f sublattices, together with the disappearance of the cooperative magnetic ordering of the R sublattice due to the breaking of the antiferromagnetic symmetry in the 3d sublattice. This is reflected in the heat-capacity curve through a smooth Schottky-like anomaly. In the case of Gd compounds the magnitude of the exchange molecular-field parameter has been deduced by fitting the magnetic contribution to the heat capacity within a simple mean-field model. From this analysis we found that this molecular field acting on the rare-earth site increases with the iron concentration, reaching values as large as 48 T for the concentration x = 6. A similar analysis of the heat capacity in the ordered phase on the Tb compounds also leads to an enhancement of the molecular field with increasing Fe content. These results allow checking the possible crystal-field parameters for these RFexMn12-x compounds.

  11. Proceedings of the International Symposium on Room Acoustics, ISRA 2010 2931 August 2010, Melbourne, Australia

    E-print Network

    North Carolina at Chapel Hill, University of

    in acoustics ABSTRACT Geometric Acoustics (GA) techniques based on the image-source method, ray tracing, beam is that of Krokstad et al. [1] based on ray tracing, as well as the image-source method [2]. During the last decadeProceedings of the International Symposium on Room Acoustics, ISRA 2010 29­31 August 2010

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

    E-print Network

    Uçar, Bora

    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

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

    PubMed Central

    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

    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

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

    PubMed

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

    2015-01-01

    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

  15. Brillouin imaging

    NASA Astrophysics Data System (ADS)

    Koski, K. J.; Yarger, J. L.

    2005-08-01

    Using an angle-dispersive Fabry-Perot interferometer in a confocal backscattering geometry, we have obtained Brillouin images of several liquid and polymer materials. One- and two-dimensional images of heterogeneous samples are presented using longitudinal Brillouin frequency shifts and acoustic attenuation for contrast. The experimental resolution of the images is 20?m.

  16. 4-[F-18]fluoroproline: A potential tracer for collagen synthesis. Radiosynthesis and biological evaluation

    SciTech Connect

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

    1996-05-01

    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.

  17. Variable temperature optoacoustic studies of 4f-states of neodymium in oxide phases

    SciTech Connect

    Beitz, J.V.; Hinaus, B.M. [Argonne National Lab., IL (United States); Huang, Jin [Wisconsin Univ., Madison, WI (United States). Dept. of Physics and Astronomy

    1993-09-01

    An apparatus for recording high sensitivity photoacoustic spectra from strongly light scattering samples has been constructed and tested at temperatures from 4 to 295K. The apparatus is suitable for use with air- or moisture-sensitive samples or radioactive samples requiring containment. Unlike an earlier ambient temperature photoacoustic study on Nd{sub 2}O{sub 3}, the photoacoustic bands observed from high purity Nd{sub 2}O{sub 3} in the present work agree well with the Stark components of 4f states of Nd{sup 3+} in A-type Nd{sub 2}O{sub 3} as assigned by Caro, Derouet, and Beaury.

  18. XeCl laser pumped iodine laser using t-C4F9I

    NASA Technical Reports Server (NTRS)

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

    1989-01-01

    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.

  19. XeCl laser pumped iodine laser using t-C4F9I

    NASA Technical Reports Server (NTRS)

    Hwang, In Heon; Han, Kwang S.

    1989-01-01

    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.

  20. Predictions for e+ e- -> WW -> 4f(gamma) at a future linear collider

    E-print Network

    A. Denner; S. Dittmaier; M. Roth; D. Wackeroth

    2001-01-23

    We describe the salient features of precise predictions for the processes e+ e- -> WW -> 4f(gamma) as obtained with the Monte Carlo generator RacoonWW, including the complete O(alpha) electroweak radiative corrections in the double-pole approximation. Numerical results for some distributions are given at the typical linear-collider energy \\sqrt{s}=500 GeV. Moreover, we study the impact of the non-universal electroweak corrections by comparing with results of an improved Born approximation.

  1. Panel acoustic contribution analysis.

    PubMed

    Wu, Sean F; Natarajan, Logesh Kumar

    2013-02-01

    Formulations are derived to analyze the relative panel acoustic contributions of a vibrating structure. The essence of this analysis is to correlate the acoustic power flow from each panel to the radiated acoustic pressure at any field point. The acoustic power is obtained by integrating the normal component of the surface acoustic intensity, which is the product of the surface acoustic pressure and normal surface velocity reconstructed by using the Helmholtz equation least squares based nearfield acoustical holography, over each panel. The significance of this methodology is that it enables one to analyze and rank relative acoustic contributions of individual panels of a complex vibrating structure to acoustic radiation anywhere in the field based on a single set of the acoustic pressures measured in the near field. Moreover, this approach is valid for both interior and exterior regions. Examples of using this method to analyze and rank the relative acoustic contributions of a scaled vehicle cabin are demonstrated. PMID:23363099

  2. Acoustic transducer

    DOEpatents

    Drumheller, D.S.

    1997-12-30

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

  3. Acoustic transducer

    DOEpatents

    Drumheller, Douglas S. (Cedar Crest, NM)

    1997-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    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.

  5. Acoustic emission monitoring system

    Microsoft Academic Search

    Romrell; Delwin M

    1977-01-01

    Methods and apparatus for identifying the source location of acoustic emissions generated within an acoustically conductive medium. A plurality of acoustic receivers are communicably coupled to the surface of the medium at a corresponding number of spaced locations. The differences in the reception time of the respective sensors in response to a given acoustic event are measured among various sensor

  6. Apolipoprotein A-I mimetic peptide L-4F prevents myocardial and coronary dysfunction in diabetic mice

    PubMed Central

    Vecoli, C.; Cao, J.; Neglia, D.; Inoue, K.; Sodhi, K.; Vanella, L.; Gabrielson, K. K.; Bedja, D.; Paolocci, N.; L'Abbate, A.; Abraham, N. G.

    2011-01-01

    Diabetes is a major health problem associated with adverse cardiovascular outcomes. The apolipoprotein A-I mimetic peptide L-4F is a putative anti-diabetic drug, has antioxidant and anti-inflammatory proprieties and improves endothelial function. In obese mice L-4F increases adiponectin levels, improving insulin sensitivity and reducing visceral adiposity. We hypothesized that the pleiotropic actions of L-4F can prevent heart and coronary dysfunction in a mouse model of genetically induced Type II diabetes. We treated db/db mice with either L-4F or vehicle for 8 weeks. Trans-thoracic echocardiography was performed; thereafter, isolated hearts were subjected to ischemia/reperfusion (IR). Glucose, insulin, adiponectin, and pro-inflammatory cytokines (IL-1?, TNF-?, MCP-1) were measured in plasma and HO-1, pAMPK, peNOS, iNOS, adiponectin and superoxide in cardiac tissue. In db/db mice L-4F decreased accumulation of subcutaneous and total fat, and increased insulin sensitivity and adiponectin levels while lowering inflammatory cytokines (p<0.05). L-4F normalized in vivo left ventricular (LV) function of db/db mice, increasing (p<0.05) fractional shortening and decreasing (p<0.05) LV dimensions. In I/R experiments, L-4F prevented coronary microvascular resistance from increasing and LV function from deteriorating in the db/db mice. These changes were associated with increased cardiac expression of HO-1, pAMPK, peNOS and adiponectin and decreased levels of superoxide and iNOS (p<0.01). In the present study we showed that L-4F prevented myocardial and coronary functional abnormalities in db/db mice. These effects were associated with stimulation of HO-1 resulting in increased levels of anti-inflammatory, anti-oxidative, and vasodilatatory action through a mechanism involving increased levels of adiponectin, pAMPK and peNOS. PMID:21598304

  7. Charcot-Marie-Tooth type 4F disease caused by S399fsx410 mutation in the PRX gene.

    PubMed

    Kabzinska, D; Drac, H; Sherman, D L; Kostera-Pruszczyk, A; Brophy, P J; Kochanski, A; Hausmanowa-Petrusewicz, I

    2006-03-14

    Charcot-Marie-Tooth type 4F disease (CMT4F) is an autosomal recessive neuropathy caused by mutations in the PRX gene. To date, only seven mutations have been identified in the PRX gene. In this study, the authors report a novel S399fsX410 mutation in the PRX gene and its effects at the protein level, which was identified in an 8-year-old patient with early-onset CMT disease. PMID:16534116

  8. Sexual Dimorphism and Tissue Specificity in the Expression of CYP4F Forms in Sprague Dawley Rats

    Microsoft Academic Search

    AUINASH KALSOTRA; SAYEEPRIYADARSHINI ANAKK; CHRISTOPHER L. BOEHME; HENRY W. STROBEL

    2002-01-01

    The cytochromes P450 belong to a superfamily of enzymes in- volved in a diverse array of endobiotic and xenobiotic metabolic pathways. Several members of a novel family of cytochrome P450 (CYP4F), which specifically mediate leukotriene B4 -hydroxyla- tion, have now been identified in various species including rat, mouse, and human. In rats, the CYP4F family consists of four related genes,

  9. Acoustic shear wave displacement measurement using ultrasound

    Microsoft Academic Search

    Vinayak Dutt; Randall R. Kinnick; James F. Greenleaf

    1996-01-01

    Echo ultrasound can be used to detect and measure acoustic shear waves. Earlier it has been shown that a phase contrast based magnetic resonance imaging technique can be used for cyclic shear wave displacement measurement. Echo ultrasound presents an alternate method for imaging of such shear waves. The ultrasound based method uses the phase of quadrature echo signals to estimate

  10. Near-field acoustic streaming jet

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

    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.

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

    PubMed Central

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

    2013-01-01

    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

  12. Active acoustic metamaterials reconfigurable in real time

    NASA Astrophysics Data System (ADS)

    Popa, Bogdan-Ioan; Shinde, Durvesh; Konneker, Adam; Cummer, Steven A.

    2015-06-01

    A major limitation of current acoustic metamaterials is that their acoustic properties are either locked into place once fabricated or are only modestly tunable, tying them to the particular application for which they are designed. We present a design approach that yields active metamaterials whose physical structure is fixed, yet their local acoustic response can be changed almost arbitrarily and in real time by configuring the digital electronics that control the metamaterial acoustic properties. We demonstrate this approach experimentally by designing a metamaterial slab configured to act as a very thin acoustic lens that manipulates differently three identical, consecutive pulses incident on the lens. Moreover, we show that the slab can be configured to simultaneously implement various roles, such as that of a lens and a beam steering device. Finally, we show that the metamaterial slab is suitable for efficient second harmonic acoustic imaging devices capable of overcoming the diffraction limit of linear lenses. These advantages demonstrate the versatility of this active metamaterial and highlight its broad applicability, in particular, to acoustic imaging.

  13. Differential phase acoustic microscope for micro-NDE

    NASA Technical Reports Server (NTRS)

    Waters, David D.; Pusateri, T. L.; Huang, S. R.

    1992-01-01

    A differential phase scanning acoustic microscope (DP-SAM) was developed, fabricated, and tested in this project. This includes the acoustic lens and transducers, driving and receiving electronics, scanning stage, scanning software, and display software. This DP-SAM can produce mechanically raster-scanned acoustic microscopic images of differential phase, differential amplitude, or amplitude of the time gated returned echoes of the samples. The differential phase and differential amplitude images provide better image contrast over the conventional amplitude images. A specially designed miniature dual beam lens was used to form two foci to obtain the differential phase and amplitude information of the echoes. High image resolution (1 micron) was achieved by applying high frequency (around 1 GHz) acoustic signals to the samples and placing two foci close to each other (1 micron). Tone burst was used in this system to obtain a good estimation of the phase differences between echoes from the two adjacent foci. The system can also be used to extract the V(z) acoustic signature. Since two acoustic beams and four receiving modes are available, there are 12 possible combinations to produce an image or a V(z) scan. This provides a unique feature of this system that none of the existing acoustic microscopic systems can provide for the micro-nondestructive evaluation applications. The entire system, including the lens, electronics, and scanning control software, has made a competitive industrial product for nondestructive material inspection and evaluation and has attracted interest from existing acoustic microscope manufacturers.

  14. Liquid acoustic lens for photoacoustic tomography.

    PubMed

    Song, Chaolong; Xi, Lei; Jiang, Huabei

    2013-08-01

    Recently, intensive research has been conducted to accelerate the development of photoacoustic (PA) imaging modality for biomedical applications. The use of acoustic lenses to collect ultrasound signals is of great interest. This Letter presents the design and fabrication of a liquid acoustic diverging lens, which can enlarge the acceptance angle of an ultrasound transducer. This lens possesses an inherent advantage of low acoustic impedance and the convenience to be attached to or detached from a commercial flat transducer. Phantom experiments have been carried out to demonstrate the improvement of using such a liquid lens over using a bare transducer for PA tomography. PMID:23903182

  15. Acoustic impedance microscopy for biological tissue characterization.

    PubMed

    Kobayashi, Kazuto; Yoshida, Sachiko; Saijo, Yoshifumi; Hozumi, Naohiro

    2014-09-01

    A new method for two-dimensional acoustic impedance imaging for biological tissue characterization with micro-scale resolution was proposed. A biological tissue was placed on a plastic substrate with a thickness of 0.5mm. A focused acoustic pulse with a wide frequency band was irradiated from the "rear side" of the substrate. In order to generate the acoustic wave, an electric pulse with two nanoseconds in width was applied to a PVDF-TrFE type transducer. The component of echo intensity at an appropriate frequency was extracted from the signal received at the same transducer, by performing a time-frequency domain analysis. The spectrum intensity was interpreted into local acoustic impedance of the target tissue. The acoustic impedance of the substrate was carefully assessed prior to the measurement, since it strongly affects the echo intensity. In addition, a calibration was performed using a reference material of which acoustic impedance was known. The reference material was attached on the same substrate at different position in the field of view. An acoustic impedance microscopy with 200×200 pixels, its typical field of view being 2×2 mm, was obtained by scanning the transducer. The development of parallel fiber in cerebella cultures was clearly observed as the contrast in acoustic impedance, without staining the specimen. The technique is believed to be a powerful tool for biological tissue characterization, as no staining nor slicing is required. PMID:24852259

  16. Acoustic cryocooler

    DOEpatents

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

    1990-01-01

    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.

  17. Acoustic cryocooler

    SciTech Connect

    Swift, G.W.; Martin, R.A.; Radebaugh, R.

    1989-09-26

    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 maintain a cooling load of 5 W at 80 K. 3 figs.

  18. Acoustic cryocooler

    SciTech Connect

    Swift, G.W.; Martin, R.A.; Radebaugh, R.

    1990-09-04

    This patent describes 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 effect 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 maintain a cooling load of 5 W at 80 K.

  19. Acoustic transducer

    DOEpatents

    Drumheller, Douglas S. (Cedar Crest, NM)

    2000-01-01

    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.

  20. Decision Making in Acoustic Neuroma Management

    PubMed Central

    Naguib, Maged B.; Saleh, Essam; Aristegui, Miguel; Mazzoni, Antonio; Sanna, Mario

    1994-01-01

    Patients with acoustic neuroma in their only hearing ear are not frequently seen in clinical practice. Managing this group of patients is a challenge to both patient and surgeon. In this study we report on five cases of acoustic neuroma in an only hearing ear. Our decision for nonsurgical management of those patients with regular follow-up using auditory brainstem responses and magnetic resonance imaging is discussed. Other management options currently available are considered as well. PMID:17170923

  1. Acoustic telemetry.

    SciTech Connect

    Drumheller, Douglas Schaeffer; Kuszmaul, Scott S.

    2003-08-01

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

  2. Semi-analytical computation of the acoustic field of a segment of a cylindrically concave transducer in lossless and

    E-print Network

    Miller, Eric

    of elements that are curved or by the use of an acoustic lens. In the image, or scan plane, the elementsSemi-analytical computation of the acoustic field of a segment of a cylindrically concave. Acoust. Soc. Am. 49, 1627­1638 1971 is developed to compute the acoustic field of a rectangular element

  3. Real-time sonar system using acoustic lens and numerical analysis based on 2D\\/3D parabolic equation method

    Microsoft Academic Search

    Y. Takasea; T. Anadaa; T. Tsuchiyaa; N. Endoha; N. Nakamura; T. Tukioka

    2005-01-01

    The autonomous underwater vehicle mounted on the forward obstacle avoidance sonar is developed to investigate ocean environments. In order to obtain real time, high efficiency and clear acoustic images, the real-time sonar system using an acoustic lens has been studied. The propagation of sound through acoustic lenses can be modeled using either the ray-tracing, wave acoustics or a combination of

  4. Design and Experimental Applications of Acoustic Metamaterials

    NASA Astrophysics Data System (ADS)

    Zigoneanu, Lucian

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

  5. Pu 4f XPS spectra analyzed in the Anderson impurity model

    SciTech Connect

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

    1998-05-09

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

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

    PubMed Central

    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

    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

  7. Opto-acoustic thrombolysis

    DOEpatents

    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

    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.

  8. Acoustic Propagation Considerations for Underwater Acoustic Communications Network Development

    E-print Network

    Zhou, Shengli

    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

  9. MINIMUM RISK ACOUSTIC CLUSTERING FOR MULTILINGUAL ACOUSTIC MODEL COMBINATION

    E-print Network

    Byrne, William

    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

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

    PubMed Central

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

    2014-01-01

    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 knockout 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

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

    PubMed Central

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

    2014-01-01

    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

  12. What Is an Acoustic Neuroma

    MedlinePLUS

    What is an Acoustic Neuroma? Important Points To Know About an Acoustic Neuroma An acoustic neuroma , also called a vestibular schwannoma, is a ... may be genetic in some cases. If an acoustic tumor becomes large it may push on the ...

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  14. Photoacoustic imaging platforms for multimodal imaging

    PubMed Central

    2015-01-01

    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

  15. 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

  16. Expression and characterization of human cytochrome P450 4F11: Putative role in the metabolism of therapeutic drugs and eicosanoids.

    PubMed

    Kalsotra, Auinash; Turman, Cheri M; Kikuta, Yasushi; Strobel, Henry W

    2004-09-15

    We previously reported the cDNA cloning of a new CYP4F isoform, CYP4F11. In the present study, we have expressed CYP4F11 in Saccharomyces cerevisiae and examined its catalytic properties towards endogenous eicosanoids as well as some clinically relevant drugs. CYP4F3A, also known as a leukotriene B4 omega-hydroxylase, was expressed in parallel for comparative purposes. Our results show that CYP4F11 has a very different substrate profile than CYP4F3A. CYP4F3A metabolized leukotriene B4, lipoxins A4 and B4, and hydroxyeicosatetraenoic acids (HETEs) much more efficiently than CYP4F11. On the other hand, CYP4F11 was a better catalyst than CYP4F3A for many drugs such as erythromycin, benzphetamine, ethylmorphine, chlorpromazine, and imipramine. Erythromycin was the most efficient substrate for CYP4F11, with a Km of 125 microM and Vmax of 830 pmol min(-1) nmol(-1) P450. Structural homology modeling of the two proteins revealed some interesting differences in the substrate access channel including substrate recognition site 2 (SRS2). The model of CYP4F11 presents a more open access channel that may explain the ability to metabolize large molecules like erythromycin. Also, some wide variations in residue size, charge, and hydrophobicity in the FG loop region may contribute to differences in substrate specificity and activity between CYP4F3A and CYP4F11. PMID:15364545

  17. Real-time virtual room acoustic simulation

    NASA Astrophysics Data System (ADS)

    Carneal, James P.; Johnson, Jan; Johnson, Troge; Johnson, Marty

    2003-10-01

    A realistic virtual room acoustic simulation has been implemented on a PC-based computer in near real-time. Room acoustics are calculated by the image source method using realistic absorption coefficients for a variety of realistic surfaces and programmed in MATLAB. The resulting impulse response filters are then applied in near real-time using fast convolution DSP techniques using data being read from a CD-ROM. The system was implemented in a virtual acoustic room facility. Optimizations have been performed to retain the realistic virtual room effect while minimizing computations through limited psycho-acoustic testing. In general, realistic anechoic to reverberant virtual rooms have been re-created with six 8192 coefficient filters. To provide realistic simulations, special care must be taken to accurately reproduce the low frequency acoustics. Since the virtual room acoustic facility was not totally anechoic (as are most anechoic chambers), inverse filters were applied to compensate for over-amplified acoustics at frequencies below 350 Hz.

  18. Identifying the Acoustic Neuroma

    MedlinePLUS

    ... Search ANAUSA.org Connect with us! Identifying the Acoustic Neuroma Advances in medicine have made possible the identification of small acoustic neuromas (those still confined to the internal auditory ...

  19. Symptoms of Acoustic Neuroma

    MedlinePLUS

    ... Search ANAUSA.org Connect with us! Symptoms of Acoustic Neuroma Early symptoms are easily overlooked, thus making ... are symptoms, however, indicating the possibility of an acoustic neuroma . The first symptom in 90% of those ...

  20. Ultrafast dynamics of folded acoustic phonons from semiconductor superlattices

    Microsoft Academic Search

    Mariano Trigo

    2008-01-01

    There is great interest in the coherent control of short-wavelength acoustic phonons using ultrafast laser pulses for applications such as imaging and energy transport. Metallic layers have been used extensively as optical transducers for generation and measurement of strain pulses. This approach is usually limited to a few hundred Ghz. The folding of the acoustic branches in periodic superlattices provides

  1. An Overview of Channel Coding For Underwater Acoustic Communications

    E-print Network

    Paris-Sud XI, Université de

    An Overview of Channel Coding For Underwater Acoustic Communications Joël Trubuil, André Goalic-rate underwater acoustic link for images, text and data transmission. Later, the speech option was added, and more in reception. After system validation in static conditions, in the Penfeld river in Brest, France, sea trials

  2. MAPPING FISHERIES HABITATS BY ENHANCED MULTIBEAM ACOUSTIC DATA IN ALASKA

    Microsoft Academic Search

    Gary Greene

    1.0 ABSTRACT New acoustic data processing methods developed by Fugro Pelagos, Inc. (FPI) have greatly improved the ability to display textural characteristics of the seafloor. This paper illustrates how digital multibeam swath bathymetry and acoustic backscatter images can be used to produce higher resolution for applications for developing marine benthic habitat maps. These techniques may resolve unique bottom features such

  3. Underwater Laser Plasma Acoustic Source Directivity and Frequency Control Demonstration

    Microsoft Academic Search

    T. G. Jones; M. Hornstein; A. Ting; M. Nicholas

    2009-01-01

    A remote underwater laser acoustic source is under development at NRL. Sound is generated by intense laser pulses propagating through air and water, followed by underwater optical compression and laser-induced breakdown (LIB). Such an acoustic source would be useful for communications, navigation, and sonar imaging. Recent experiments demonstrated control of the shape of the LIB plasma volume, and thereby control

  4. Acoustic emission frequency discrimination

    NASA Technical Reports Server (NTRS)

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

    1988-01-01

    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.

  5. AT, an Acoustic Transmissometer

    Microsoft Academic Search

    A. J. Williams

    2008-01-01

    The combination of attenuation measurement with acoustic travel-time current measurement along a common path has produced a new acoustic sensor of suspended particles, the acoustic transmissometer (AT). The AT has been deployed in the OASIS experiment, a particle-measuring experiment to determine suspended particle properties resulting from turbulence and current near the seabed. Acoustic transmission at 1.8 MHz, as used in

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

    PubMed

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

    2014-09-28

    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

  7. Tutorial on architectural acoustics

    NASA Astrophysics Data System (ADS)

    Shaw, Neil; Talaske, Rick; Bistafa, Sylvio

    2002-11-01

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

  8. Designing Acoustic Thresholds

    Microsoft Academic Search

    Pedro Rebelo; Maarten van Walstijn

    This paper introduces the notion of acoustic thresholds as a metaphor for the design of sound objects. We present an approach to sound design which is based on the idea of intervention rather than creation, actively transforming sound by manipulating the acoustic entity itself. By addressing the acoustic specificity of sound objects, as in physical modelling, and by introducing technological

  9. Acoustic Heating Peter Ulmschneider

    E-print Network

    Ulmschneider, Peter

    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

  10. Generation and control of sound bullets with a nonlinear acoustic lens

    Microsoft Academic Search

    A. Spadoni; C. Daraio

    2010-01-01

    Acoustic lenses are employed in a variety of applications, from biomedical imaging and surgery, to defense systems, but their performance is limited by their linear operational envelope and complexity. Here we show a dramatic focusing effect and the generation of large amplitude, compact acoustic pulses (sound bullets) in solid and fluid media, enabled by a tunable, highly nonlinear acoustic lens.

  11. Numerical Analysis of Underwater Acoustic Lens Using Wide-Angle Parabolic Equation Method

    Microsoft Academic Search

    Tetsuo Anada; Takenobu Tsuchiya; Nobuyuki Endoh; Toshiaki Nakamura; Tetsu Tsukioka; Taro Aoki; Ieharu Kaiho

    2002-01-01

    The autonomous underwater vehicle mounted on the forward obstacle avoidance sonar is developed to investigate ocean environments such as that of the Arctic Ocean. In order to obtain real time, high efficiency and clear acoustic images, the acoustic lens sonar system has been adopted. Usually, the design of the acoustic lens as well as that of the optical lens is

  12. A Beam Tracing Approach to Acoustic Modeling for Interactive Virtual Environments

    E-print Network

    Singh, Jaswinder Pal

    A Beam Tracing Approach to Acoustic Modeling for Interactive Virtual Environments Thomas Funkhouser environment research has focused on interactive image gen- eration and has largely ignored acoustic modeling, comprehension, and sense of presence in virtual environments. A primary challenge in acoustic model- ing

  13. RTO-MP-HFM-123 15 -1 Evaluation of Acoustic Propagation Paths into the Human Head

    E-print Network

    Illinois at Urbana-Champaign, University of

    a digital image database of an adult male head. Coupled acoustic-mechanical finite-element analysis (FEARTO-MP-HFM-123 15 - 1 Evaluation of Acoustic Propagation Paths into the Human Head Prof. Dr: wdo@uiuc.edu / yuhuiliu@uiuc.edu SUMMARY The overall goal has been to develop an acoustic wave

  14. Full-circular surface acoustic wave excitation for high resolution acoustic microscopy using spherical lens and time gate technology

    Microsoft Academic Search

    Isao Ishikawa; Kageyoshi Katakura; Yukio Ogura

    1999-01-01

    With a fixed gate width under the condition where the focus of an acoustic lens was set inside the sample, we varied signal taking-in time. Discrimination was made between differences in time required for an ultrasonic signal reflected from the sample to reach the acoustic lens. This process also enabled three types of images to be obtained separately: the surface

  15. A Search for EUV Emission from the O4f Star Zeta Puppis

    NASA Technical Reports Server (NTRS)

    Waldron, Wayne L.; Vallerga, John

    1996-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    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).

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

    SciTech Connect

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

    2005-03-01

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

  18. 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

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

    2013-08-15

    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.

  19. A study of acoustic source generation mechanism of Magnetoacoustic Tomography.

    PubMed

    Wang, Shigang; Zhang, Shunqi; Ma, Ren; Yin, Tao; Liu, Zhipeng

    2014-01-01

    Magnetoacoustic Tomography (MAT) is a non-invasive imaging modality for electrical conductivity with good contrast and high spatial resolution. We have analyzed the acoustic source generation mechanism of MAT and presented its physical model, including the simulations and experiments in this paper. In MAT, acoustic sources are generated in a conductive object placed in a static magnetic field. Pulsed current is injected into the object and produces a Lorentz force due to the static magnetic filed. Acoustic vibration was excited by the Lorentz force, and hence, ultrasound waves propagate in all directions and are collected with transducers placed around the object. The conductivity image can then be reconstructed with acoustic waves using some reconstruction algorithms. Because the acoustic source generation mechanism of MAT is the key problem of forward and inverse problems, we analyzed the physical process of acoustic source generation and presented the acoustic dipole source model according to the Lorentz force imposed on the object. In addition, computer simulations and experiments were also conducted. The results of simulations applying an acoustic dipole source model are consistent with experimental results. This study has cardinal significance for the accurate algorithm of MAT and provides a methodology and reference for acoustic source problems. PMID:24238804

  20. Acoustical standards news.

    PubMed

    Blaeser, Susan B; Schomer, Paul D

    2015-05-01

    American National Standards (ANSI Standards) developed by Accredited Standards Committees S1, S2, S3, S3/SC 1, and S12 in the areas of acoustics, mechanical vibration and shock, bioacoustics, animal bioacoustics, and noise, respectively, are published by the Acoustical Society of America (ASA). In addition to these standards, ASA publishes catalogs of Acoustical Standards, both National and International. To receive copies of the latest Standards catalogs, please contact Susan B. Blaeser.Comments are welcomed on all material in Acoustical Standards News.This Acoustical Standards News section in JASA, as well as the National and International Catalogs of Acoustical Standards, and other information on the Standards Program of the Acoustical Society of America, are available via the ASA home page: http://acousticalsociety.org. PMID:25994730

  1. Active acoustic metamaterials reconfigurable in real-time

    E-print Network

    Popa, Bogdan-Ioan; Konneker, Adam; Cummer, Steven A

    2015-01-01

    A major limitation of current acoustic metamaterials is that their acoustic properties are either locked into place once fabricated or only modestly tunable, tying them to the particular application for which they are designed. We present in this paper a design approach that yields active metamaterials whose physical structure is fixed, yet their local acoustic response can be changed almost arbitrarily and in real-time by configuring the digital electronics that control the metamaterial acoustic properties. We demonstrate experimentally this approach by designing a metamaterial slab configured to act as a very thin acoustic lens that manipulates differently three identical, consecutive pulses incident on the lens. Moreover, we show that the slab can be configured to implement simultaneously various roles, such as that of a lens and beam steering device. Finally, we show that the metamaterial slab is suitable for efficient second harmonic acoustic imaging devices capable to overcome the diffraction limit of l...

  2. Speech recognition for image animation and coding

    Microsoft Academic Search

    Wu Chou; H. H. Chen

    1995-01-01

    We discuss some issues related to acoustic assisted image coding and animation. An approach of talker independent acoustic assisted image coding and animation scheme is studied. A perceptually based sliding window encoder is proposed. It utilizes the high rate (or oversampled) viseme sequence from the audio domain for image domain viseme interpolation and smoothing. The image domain visemes in our

  3. RNA editing and regulation of Drosophila 4f-rnp expression by sas-10 antisense readthrough mRNA transcripts

    PubMed Central

    PETERS, NICK T.; ROHRBACH, JUSTIN A.; ZALEWSKI, BRIAN A.; BYRKETT, COLLEEN M.; VAUGHN, JACK C.

    2003-01-01

    We have previously described an example of extensively A-to-G edited cDNA derived from adult heads of the fruitfly Drosophila melanogaster. In that study, the source of the predicted antisense RNA pairing strand for template recognition by dADAR editase was not identified, and the biological significance of the observed hyperediting was not known. Here, we address each of these questions. 4f-rnp and sas-10 are closely adjacent X-linked genes located on opposite DNA strands that produce convergent transcripts. We show that developmentally regulated antisense sas-10 readthrough mRNA arises by activation of an upstream promoter P2 during the late embryo stage of fly development. The sas-10 readthrough transcripts pair with 4f-rnp mRNA to form double-stranded molecules, as indicated by A-to-G editing observed in both RNA strands. It would be predicted that perfect RNA duplexes would be targeted for modification/degradation by enzyme pathways that recognize double-stranded RNAs, leading to decline in 4f-rnp mRNA levels, and this is what we observe. The observation using quantitative RT-PCR that sas-10 readthrough and 4f-rnp transcript levels are inversely related suggests a role for the antisense RNA in posttranscriptional regulation of 4f-rnp gene expression during development. Potential molecular mechanisms that could lead to this result are discussed, one of which is targeted transcript degradation via the RNAi pathway. Insofar as the dADAR editase and RNAi pathways are known to be constitutive in this system, it is likely that control of antisense RNA transcription is the rate-limiting factor. The results provide insight into roles of naturally occurring antisense RNAs in regulation of eukaryotic gene expression. PMID:12756328

  4. Acoustics 08 Paris Finite element modeling of thermoviscous acoustics in

    E-print Network

    Boyer, Edmond

    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

  5. From oceanographic to acoustic forecasting: acoustic model calibration

    E-print Network

    Jesus, Sérgio M.

    From oceanographic to acoustic forecasting: acoustic model calibration using in situ acoustic on acoustic propagation models and envi- ronmental representations of the oceanic area in which the sonar of a propagation model. Though well developed nowadays, acoustic propagation modeling is limited in practice

  6. Systematics of 4f electron energies relative to host bands by resonant photoemission of rare-earth ions in aluminum garnets

    Microsoft Academic Search

    C. W. Thiel; H. Cruguel; H. Wu; Y. Sun; G. J. Lapeyre; R. L. Cone; R. W. Equall; R. M. Macfarlane

    2001-01-01

    The energies of trivalent rare-earth ions relative to the host valence band were measured for a series of rare-earth-doped yttrium aluminum garnets RxY3-xAl5O12 (R=Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu and 0<=x<=3), using ultraviolet photoemission spectroscopy. The 4f photoemission spectra were acquired using synchrotron radiation, exploiting the 4d to 4f ``giant resonance'' in the 4f electron photoemission cross

  7. Experiments with the Planar Acoustic Microscope Lens

    Microsoft Academic Search

    G. W. Farnell; C. K. Jen

    1981-01-01

    The simple planar acoustic microscope lens has been used in several standard imaging experiments to demonstrate the structure of its focal spot and in particular, the lack of spherical aberration when traversing a metal. The ease of fabrication allows unusual lens geometries and some properties of semicircular lenses are presented as examples in linear and non-linear operation. The pattern of

  8. Anisotropic and Negative Acoustic Index Metamaterials

    E-print Network

    Fok, Lee Ren

    2010-01-01

    at the lens exit, resulting in far-field acoustic imaging ofacoustic information including sub-diffraction limit components 8 times as it traversed the lensacoustic index fluid metamaterial was motivated by the reversed wave phenomena leading to a perfect lens.

  9. Acoustic intensity simulations for regulatory compliance

    Microsoft Academic Search

    Chris M. Daft; William M. Leue; Kai E. Thomenius; Lars A. Odegaard; Michael C. MacDonald; Alan S. Meyers

    1999-01-01

    Ensuring that an ultrasound imager complies with all aspects of the FDA 510(k) regulations is a complex task, because there are hundreds of thousands of discrete operating conditions available to the sonographer. Accurate measurements require `peaking' of the hydrophone in azimuth and elevation, and acquiring data as a function of range. Thus it is necessary to characterize the acoustic field

  10. Ion Acoustic Waves in Ultracold Neutral Plasmas

    SciTech Connect

    Castro, J.; McQuillen, P.; Killian, T. C. [Department of Physics and Astronomy and Rice Quantum Institute, Rice University, Houston, Texas 77005 (United States)

    2010-08-06

    We photoionize laser-cooled atoms with a laser beam possessing spatially periodic intensity modulations to create ultracold neutral plasmas with controlled density perturbations. Laser-induced fluorescence imaging reveals that the density perturbations oscillate in space and time, and the dispersion relation of the oscillations matches that of ion acoustic waves, which are long-wavelength, electrostatic, density waves.

  11. Infratentorial approach to internal acoustic meatus.

    PubMed

    Krajewski, R; Kukwa, A

    1999-01-01

    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

  12. Acoustic Translation of an Acoustically Levitated Sample

    NASA Technical Reports Server (NTRS)

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

    1986-01-01

    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.

  13. The crystal structure of bøgvadite (Na2SrBa2Al4F20)

    NASA Astrophysics Data System (ADS)

    Bali?-Žuni?, Ton?i

    2014-08-01

    The crystal structure of bøgvadite, Na2SrBa2Al4F20, has been solved and refined to a R1 factor of 4.4 % from single-crystal data (Mo K? X-ray diffraction, CCD area detector) on a sample from the cryolite deposit at Ivittuut, SW Greenland. Bøgvadite is monoclinic, P21/ n space group, with unit cell parameters a = 7.134(1), b = 19.996(3) and c = 5.3440(8) Å, ? = 90.02(1)o. A close proximity of the crystal structure to an orthorhombic symmetry and the presence of the two twin components in a nearly 1:1 ratio suggest that the investigated bøgvadite crystal has originally formed as a high-temperature orthorhombic polymorph which on cooling transformed to the stable low temperature monoclinic structure. The bøgvadite crystal structure has groupings of cation-fluoride coordination polyhedra similar to those found in the crystal structures of the genetically closely associated minerals jarlite and jørgensenite. However, its structure type is different from the latter two. The fluoridoaluminate framework of bøgvadite consists of infinite zig-zag chains of cis-connected AlF6 coordination octahedra. The 1 ?[AlF5] chains are interconnected by infinite chains of Na-F coordination polyhedra which extend in the same direction. Na is coordinated by nine F atoms if its full surrounding is taken in consideration, but makes significant chemical bonds only to closest five. The chains of AlF6 and NaF9 coordination polyhedra form double layers. In the centre of layers, relatively large voids in the form of pentagonal antiprisms are occupied by Sr atoms which make chemical bonds with the closest six F atoms. Between the SrF10 coordinations in the centre of layers run empty channels. The double layers are interconnected by Ba atoms which are coordinated by eight F atoms and fill the spaces between the layers. Bøgvadite belongs to the group of fluoridoaluminates with infinite chains of cis-connected AlF6 coordination octahedra, alike those found in the crystal structures of Ba-fluoridoaluminates.

  14. Natural History of Acoustic Neuromas

    PubMed Central

    Valvassori, Galdino E.; Shannon, Michael

    1991-01-01

    The growth rate of acoustic neuromas was studied in a series of 50 patients who underwent follow-up imaging studies, since surgery was not performed after the initial diagnostic study or only performed after the follow-up studies. In 50% of the cases the tumor did not grow during the length of the follow-up. In the other patients the growth was less than 50% of the original tumor size in all but four. No correlation was observed between tumor growth, length of the follow-up, and age of the patient. Our results suggest a change in the management of this benign tumor. PMID:17170806

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

    E-print Network

    Kushner, Mark

    of these processes for different materials e.g., etching of SiO2 vs Si3N4) have resulted in the use of a wide variety of fluorocarbon gases e.g., CHF3 , C2F6 , and c-C4F8) and numerous additives e.g., O2 , N2 , CO, and Ar , and CO are often used for the plasma etching of silicon dioxide. Gas phase reaction mechanisms

  16. Low frequency acoustic microscope

    DOEpatents

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

    1986-11-04

    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.

  17. 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....

  18. Acoustic Levitation With Less Equipment

    NASA Technical Reports Server (NTRS)

    Barmatz, M. B.; Jacobi, N.

    1983-01-01

    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.

  19. Acoustic superfocusing by solid phononic crystals

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    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.

  20. Modeling and prediction of density distribution and microstructure in particleboards from acoustic properties by correlation of non-contact high-resolution pulsed air-coupled ultrasound and X-ray images.

    PubMed

    Sanabria, Sergio J; Hilbers, Ulrich; Neuenschwander, Jürg; Niemz, Peter; Sennhauser, Urs; Thömen, Heiko; Wenker, Jan L

    2013-01-01

    Non-destructive density and microstructure quality control testing in particleboards (PBs) is necessary in production lines. A pulsed air-coupled ultrasound (ACU) high-resolution normal transmission system, together with a first wave tracking algorithm, were developed to image amplitude transmission G(p) and velocity c(p) distributions at 120kHz for PBs of specific nominal densities and five particle geometries, which were then correlated to X-ray in-plane density images ?(s). Test PBs with a homogeneous vertical density profile were manufactured in a laboratory environment and conditioned in a standard climate (T=20°C, RH=65%) before the measurements. Continuous trends (R(2)>0.97) were obtained by matching the lateral resolution of X-ray images with the ACU sound field radius (?(w)(o)=21mm) and by clustering the scatter plots. ?(s)?c(p) was described with a three-parameter non-linear model for each particle geometry, allowing for ACU density prediction with 3% uncertainty and PB testing according to EN312. ?(s)?G(p) was modeled by calculating ACU coupling gain and by fitting inverse power laws with offset of ?(s) and c(p) to material attenuation, which scaled with particle volume. G(p) and c(p) variations with the frequency were examined, showing thickness resonances and scattering attenuation. The combination of ACU and X-ray data enabled successful particle geometry classification. The observed trends were interpreted in terms of multi-scale porosity and grain scattering with finite-difference time-domain simulations, which modeled arbitrarily complex stiffness and density distributions. The proposed method allows for non-contact determination of relations between acoustic properties and in-plane density distribution in plate materials. In future work, commercial PBs with non-uniform vertical density profiles should be investigated. PMID:22677469