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Sample records for acoustic 4f imaging

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

    E-print Network

    Kingsbury, Nick

    properties of wavelets . . . . . . . . . . . . . . . . . . . . . . 78 5 Video Compression and Motion.) · Iain E G Richardson, H.264 and MPEG-4 Video Compression, John Wiley, 2003. (Advanced ­ only Vision and Image Characteristics useful for Compression 3 1.1 Introduction

  2. Nonlinear optical measurements using a 4f coherent imaging system with phase objects

    SciTech Connect

    Boudebs, G.; Cherukulappurath, S.

    2004-05-01

    We report a one-laser-shot measurement technique using a phase object at the entry of a 4f coherent imaging system to characterize the value of the nonlinear refractive index of materials placed in the Fourier plane of the setup. Experimental and simulated images are presented here in order to validate our approach. We show that the use of a quarter-wavelength dephasing object maximizes the transmission variations in the detected image. We show also that the use of phase objects increases significantly the sensitivity of the measurement compared to top-hat beams (by a factor of 6). Moreover, by adding this type of object at the entry of our imaging system it is possible to determine the sign of the refractive nonlinearity.

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

    SciTech Connect

    Cheng, Ying; Liu, XiaoJun; State Key Laboratory of Acoustics, Institute of Acoustics, Chinese Academy of Sciences, Beijing 100190 ; Zhou, Chen; Wei, Qi; Wu, DaJian

    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.

  4. 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

  5. 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.

  6. 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.

  7. First images of thunder: Acoustic imaging of triggered lightning

    NASA Astrophysics Data System (ADS)

    Dayeh, M. A.; Evans, N. D.; Fuselier, S. A.; Trevino, J.; Ramaekers, J.; Dwyer, J. R.; Lucia, R.; Rassoul, H. K.; Kotovsky, D. A.; Jordan, D. M.; Uman, M. A.

    2015-07-01

    An acoustic camera comprising a linear microphone array is used to image the thunder signature of triggered lightning. Measurements were taken at the International Center for Lightning Research and Testing in Camp Blanding, FL, during the summer of 2014. The array was positioned in an end-fire orientation thus enabling the peak acoustic reception pattern to be steered vertically with a frequency-dependent spatial resolution. On 14 July 2014, a lightning event with nine return strokes was successfully triggered. We present the first acoustic images of individual return strokes at high frequencies (>1 kHz) and compare the acoustically inferred profile with optical images. We find (i) a strong correlation between the return stroke peak current and the radiated acoustic pressure and (ii) an acoustic signature from an M component current pulse with an unusual fast rise time. These results show that acoustic imaging enables clear identification and quantification of thunder sources as a function of lightning channel altitude.

  8. Acoustic 3D imaging of dental structures

    SciTech Connect

    Lewis, D.K.; Hume, W.R.; Douglass, G.D.

    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.

  9. 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").

  10. 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.

  11. Acoustic Imaging of Snowpack Physical Properties

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

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

  12. Quantitative thermo-acoustic imaging: An exact reconstruction formula

    E-print Network

    Garnier, Josselin

    -electric tomography [3, 2, 6, 9, 13, 21, 32, 33], magnetic resonance electrical impedance tomography [20, 28, 26], magnetic resonance elastography [8, 25, 23], impedance-acoustic tomography [18], photo-acoustic [31, 22, 4 and high-contrast imaging [1, 17]. Quantitative thermo-acoustic tomography is an emerging hybrid modality

  13. 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.

  14. Interpreting Underwater Acoustic Images of the Upper Ocean Boundary Layer

    ERIC Educational Resources Information Center

    Ulloa, Marco J.

    2007-01-01

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

  15. 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.

  16. 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.

  17. Passive imaging in nondiffuse acoustic wavefields.

    PubMed

    Mulargia, Francesco; Castellaro, Silvia

    2008-05-30

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

  18. Optimization of a Biometric System Based on Acoustic Images

    PubMed Central

    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

  19. 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

  20. 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.

  1. 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

  2. Acoustic Radiation Force Elasticity Imaging in Diagnostic Ultrasound

    PubMed Central

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

    2013-01-01

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

  3. 3D acoustic imaging applied to the Baikal Neutrino Telescope

    E-print Network

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

    2008-11-07

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

  4. 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

  5. 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.

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

    PubMed Central

    Izquierdo-Fuente, Alberto; del Val, Lara; Jimnez, Mara 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

  7. Performance evaluation of a biometric system based on acoustic images.

    PubMed

    Izquierdo-Fuente, Alberto; del Val, Lara; Jimnez, Mara 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

  8. 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.

  9. Laser Imaging of Airborne Acoustic Emission by Nonlinear Defects

    NASA Astrophysics Data System (ADS)

    Solodov, Igor; Dring, Daniel; Busse, Gerd

    2008-06-01

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

  10. Optimal flushing agents for integrated optical and acoustic imaging systems

    NASA Astrophysics Data System (ADS)

    Li, Jiawen; Minami, Hataka; Steward, Earl; Ma, Teng; Mohar, Dilbahar; Robertson, Claire; Shung, Kirk; Zhou, Qifa; Patel, Pranav; Chen, Zhongping

    2015-05-01

    An increasing number of integrated optical and acoustic intravascular imaging systems have been developed and hold great promise for accurately diagnosing vulnerable plaques and guiding atherosclerosis treatment. However, in any intravascular environment, the vascular lumen is filled with blood, a high-scattering source for optical and high-frequency ultrasound signals. Blood must be flushed away to provide clearer images. To our knowledge, no research has been performed to find the ideal flushing agent for combined optical and acoustic imaging techniques. We selected three solutions as potential flushing agents for their image-enhancing effects: mannitol, dextran, and iohexol. Testing of these flushing agents was performed in a closed-loop circulation model and in vivo on rabbits. We found that a high concentration of dextran was the most useful for simultaneous intravascular ultrasound and optical coherence tomography imaging.

  11. Acoustic Molecular Imaging and Targeted Drug Delivery with Perfluorocarbon Nanoparticles

    NASA Astrophysics Data System (ADS)

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

    2005-03-01

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

  12. Ideal flushing agents for integrated optical acoustic imaging systems

    NASA Astrophysics Data System (ADS)

    Li, Jiawen; Minami, Hataka; Steward, Earl; Ma, Teng; Mohar, Dilbahar; Robertson, Claire; Shung, K. Kirk; Zhou, Qifa; Patel, Pranav M.; Chen, Zhongping

    2015-02-01

    An increased number of integrated optical acoustic intravascular imaging systems have been researched and hold great hope for accurate diagnosing of vulnerable plaques and for guiding atherosclerosis treatment. However, in any intravascular environment, vascular lumen is filled with blood, which is a high-scattering source for optical and high frequency ultrasound signals. Blood must be flushed away to make images clear. To our knowledge, no research has been performed to find the ideal flushing agent that works for both optical and acoustic imaging techniques. We selected three solutions, mannitol, dextran and iohexol, as flushing agents because of their image-enhancing effects and low toxicities. Quantitative testing of these flushing agents was performed in a closed loop circulation model and in vivo on rabbits.

  13. 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

  14. A Parallel Tracking Method for Acoustic Radiation Force Impulse Imaging

    PubMed Central

    Dahl, Jeremy J.; Pinton, Gianmarco F.; Mark, L; Agrawal, Vineet; Nightingale, Kathryn R.; Trahey, Gregg E.

    2007-01-01

    Radiation force-based techniques have been developed by several groups for imaging the mechanical properties of tissue. Acoustic Radiation Force Impulse (ARFI) imaging is one such method that uses commercially available scanners to generate localized radiation forces in tissue. The response of the tissue to the radiation force is determined using conventional B-mode imaging pulses to track micron-scale displacements in tissue. Current research in ARFI imaging is focused on producing real-time images of tissue displacements and related mechanical properties. Obstacles to producing a real-time ARFI imaging modality include data acquisition, processing power, data transfer rates, heating of the transducer, and patient safety concerns. We propose a parallel receive beamforming technique to reduce transducer heating and patient acoustic exposure, and to facilitate data acquisition for real-time ARFI imaging. Custom beam sequencing was used with a Siemens SONOLINE AntaresTM scanner to track tissue displacements with parallel-receive beam-forming in tissue-mimicking phantoms. Using simulations, the effects of material properties on parallel tracking are observed. Transducer and tissue heating for parallel tracking are compared to standard ARFI beam sequencing. The effects of tracking beam position and size of the tracked region are also discussed in relation to the size and temporal response of the region of applied force, and the impact on ARFI image contrast and signal-to-noise ratio are quantified. PMID:17328327

  15. Opto-acoustic breast imaging with co-registered ultrasound

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

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

  16. Investigation of acoustically-coupled shear layers using particle image velocimetry

    E-print Network

    Oshkai, Peter

    Investigation of acoustically-coupled shear layers using particle image velocimetry P. Oshkai, T in a duct is performed using a technique of digital particle image velocimetry. Imaging of the flow, vorticity, and streamline topology at various phases of the acoustic cycle. Global instantaneous images

  17. 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.

  18. Application of time reversal acoustics focusing for nonlinear imaging ms

    NASA Astrophysics Data System (ADS)

    Sarvazyan, Armen; Sutin, Alexander

    2001-05-01

    Time reversal acoustic (TRA) focusing of ultrasound appears to be an effective tool for nonlinear imaging in industrial and medical applications because of its ability to efficiently concentrate ultrasonic energy (close to diffraction limit) in heterogeneous media. In this study, we used two TRA systems to focus ultrasonic beams with different frequencies in coinciding focal points, thus causing the generation of ultrasonic waves with combination frequencies. Measurements of the intensity of these combination frequency waves provide information on the nonlinear parameter of medium in the focal region. Synchronized stirring of two TRA focused beams enables obtaining 3-D acoustic nonlinearity images of the object. Each of the TRA systems employed an aluminum resonator with piezotransducers glued to its facet. One of the free facets of each resonator was submerged into a water tank and served as a virtual phased array capable of ultrasound focusing and beam steering. To mimic a medium with spatially varying acoustical nonlinearity a simplest model such as a microbubble column in water was used. Microbubbles were generated by electrolysis of water using a needle electrode. An order of magnitude increase of the sum frequency component was observed when the ultrasound beams were focused in the area with bubbles.

  19. Identifying Vulnerable Plaques with Acoustic Radiation Force Impulse Imaging

    NASA Astrophysics Data System (ADS)

    Doherty, Joshua Ryan

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

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

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

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

  1. Feasibility of High Frequency Acoustic Imaging for Inspection of Containments

    SciTech Connect

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

    1998-08-01

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

  2. From Acoustic Segmentation to Language Processing: Evidence from Optical Imaging

    PubMed Central

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

    2010-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

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

  4. Acoustical imaging of spheres above a reflecting surface

    NASA Astrophysics Data System (ADS)

    Chambers, David; Berryman, James

    2003-04-01

    An analytical study using the MUSIC method of subspace imaging is presented for the case of spheres above a reflecting boundary. The field scattered from the spheres and the reflecting boundary is calculated analytically, neglecting interactions between spheres. The singular value decomposition of the response matrix is calculated and the singular vectors divided into signal and noise subspaces. Images showing the estimated sphere locations are obtained by backpropagating the noise vectors using either the free space Green's function or the Green's function that incorporates reflections from the boundary. We show that the latter Green's function improves imaging performance after applying a normalization that compensates for the interference between direct and reflected fields. We also show that the best images are attained in some cases when the number of singular vectors in the signal subspace exceeds the number of spheres. This is consistent with previous analysis showing multiple eigenvalues of the time reversal operator for spherical scatterers [Chambers and Gautesen, J. Acoust. Soc. Am. 109 (2001)]. [Work performed under the auspices of the U.S. Department of Energy by the University of California, Lawrence Livermore National Laboratory under Contract No. W-7405-Eng-48.

  5. 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, Loc.

    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.

  6. Acoustic-integrated dynamic MR imaging for a patient with obstructive sleep apnea.

    PubMed

    Chen, Yunn-Jy; Shih, Tiffany Ting-Fang; Chang, Yi-Chung; Hsu, Ying-Chieh; Huon, Leh-Kiong; Lo, Men-Tzung; Pham, Van-Truong; Lin, Chen; Wang, Pa-Chun

    2015-12-01

    Obstructive sleep apnea syndrome (OSAS) is caused by multi-level upper airway obstruction. Anatomic changes at the sites of obstruction may modify the physical or acoustic properties of snores. The surgical success of OSA depends upon precise localization of obstructed levels. We present a case of OSAS who received simultaneous dynamic MRI and snore acoustic recordings. The synchronized image and acoustic information successfully characterize the sites of temporal obstruction during sleep-disordered breathing events. PMID:26278970

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

    SciTech Connect

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

    2002-10-01

    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 employing dynamic holography using photorefractive interferometric detection. By extending the approach to ultra high frequencies, an acoustic microscope has been developed capable of operation on the nanosecond time and micron length scales. Both acoustic amplitude and phase are recorded allowing full calibration and determination of phases to within a single arbitrary constant. Results are presented of measurements at frequencies at 800-900 MHz illustrating a multitude of normal mode behavior in electrically driven thin film acoustic resonators. Coupled with microwave electrical impedance measurements, this imaging mode provides an exceptionally fast method for evaluation of electric to acoustic coupling and performance of these devices. Images of 256x240 pixels are recorded at 18Hz rates synchronized to obtain both in-phase and quadrature detection of the acoustic motion. Simple averaging provides sensitivity to the subnanometer level calibrated over the image using interferometry. Identification of specific acoustic modes and their relationship to electrical impedance characteristics show the advantages and overall high speed of the technique.

  8. Acoustic multimode interference and self-imaging phenomena realized in multimodal phononic crystal waveguides

    NASA Astrophysics Data System (ADS)

    Zou, Qiushun; Yu, Tianbao; Liu, Jiangtao; Liu, Nianhua; Wang, Tongbiao; Liao, Qinghua

    2015-09-01

    We report an acoustic multimode interference effect and self-imaging phenomena in an acoustic multimode waveguide system which consists of M parallel phononic crystal waveguides (M-PnCWs). Results show that the self-imaging principle remains applicable for acoustic waveguides just as it does for optical multimode waveguides. To achieve the dispersions and replicas of the input acoustic waves produced along the propagation direction, we performed the finite element method on M-PnCWs, which support M guided modes within the target frequency range. The simulation results show that single images (including direct and mirrored images) and N-fold images (N is an integer) are identified along the propagation direction with asymmetric and symmetric incidence discussed separately. The simulated positions of the replicas agree well with the calculated values that are theoretically decided by self-imaging conditions based on the guided mode propagation analysis. Moreover, the potential applications based on this self-imaging effect for acoustic wavelength de-multiplexing and beam splitting in the acoustic field are also presented.

  9. Characterizing Response to Elemental Unit of Acoustic Imaging Noise: An fMRI Study

    PubMed Central

    Luh, Wen-Ming; Talavage, Thomas M.

    2010-01-01

    Acoustic imaging noise produced during functional magnetic resonance imaging (fMRI) studies can hinder auditory fMRI research analysis by altering the properties of the acquired time-series data. Acoustic imaging noise can be especially confounding when estimating the time course of the hemodynamic response (HDR) in auditory event-related fMRI (fMRI) experiments. This study is motivated by the desire to establish a baseline function that can serve not only as a comparison to other quantities of acoustic imaging noise for determining how detrimental is one's experimental noise, but also as a foundation for a model that compensates for the response to acoustic imaging noise. Therefore, the amplitude and spatial extent of the HDR to the elemental unit of acoustic imaging noise (i.e., a single ping) associated with echoplanar acquisition were characterized and modeled. Results from this fMRI study at 1.5 T indicate that the group-averaged HDR in left and right auditory cortex to acoustic imaging noise (duration of 46 ms) has an estimated peak magnitude of 0.29% (right) to 0.48% (left) signal change from baseline, peaks between 3 and 5 s after stimulus presentation, and returns to baseline and remains within the noise range approximately 8 s after stimulus presentation. PMID:19304477

  10. 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 ...

  11. 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 refractionprogressive curvaturenegative 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.

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

    SciTech Connect

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

    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.

  13. 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.

  14. Towards Acoustic Structure from Motion for Imaging Sonar Tiffany A. Huang and Michael Kaess

    E-print Network

    Kaess, Michael

    Towards Acoustic Structure from Motion for Imaging Sonar Tiffany A. Huang and Michael Kaess scene structure from multiple 2D sonar images, while at the same time localizing the sonar. Imaging sonar or forward looking sonar (FLS) is commonly used for autonomous underwater vehicle (AUV) navigation

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. The path to COVIS: A review of acoustic imaging of hydrothermal flow regimes

    NASA Astrophysics Data System (ADS)

    Bemis, Karen G.; Silver, Deborah; Xu, Guangyu; Light, Russ; Jackson, Darrell; Jones, Christopher; Ozer, Sedat; Liu, Li

    2015-11-01

    Acoustic imaging of hydrothermal flow regimes started with the incidental recognition of a plume on a routine sonar scan for obstacles in the path of the human-occupied submersible ALVIN. Developments in sonar engineering, acoustic data processing and scientific visualization have been combined to develop technology which can effectively capture the behavior of focused and diffuse hydrothermal discharge. This paper traces the development of these acoustic imaging techniques for hydrothermal flow regimes from their conception through to the development of the Cabled Observatory Vent Imaging Sonar (COVIS). COVIS has monitored such flow eight times a day for several years. Successful acoustic techniques for estimating plume entrainment, bending, vertical rise, volume flux, and heat flux are presented as is the state-of-the-art in diffuse flow detection.

  20. Biosonar acoustic images for target localization and classification by bats

    NASA Astrophysics Data System (ADS)

    Simmons, James A.

    1997-07-01

    Echolocating bats use sonar to guide interception of insects, recognize objects by shape, and even track prey in clutter. Broadcasts of the big brown bat are 0.5 to 20 ms FM signals in the 20-100 kHz ultrasonic band. Insects consist of several reflecting glints, each equivalent in cross- section to a small sphere of 2 mm to 2 cm radius, while clutter is typically composed of numerous glints distributed over a large volume. The bats' signals extend in space for many target lengths, while ka values for each glint are 0.5 to 30 across the broadcast band. Bats perceive acoustic images having echo delay as their primary dimension, and space is perceived in terms of the distribution of target glints in range. Range disparities between the ears provide two 'looks' at each target from slightly different locations as well as information about azimuth. The bats auditory system encodes the FM sweeps of broadcasts and echoes as linear-period spectrograms with integration-times of 300-400 micrometers . Bats nevertheless perceive individual glints in targets for echo-delay separations well inside the integration-time window. Deconvolution is achieved by spectrogram correlation in the time domain and spectral shape transformation in the frequency-domain, with all output evidently being displayed in the time domina. Neural responses in the bat's auditory system seem limited in time precision to 20-50 micrometers at best and 300 microsecond(s) to 3 ms in a broader sample, and stimulus phase is thought to be lost for frequencies above 1-3 kHz. Yet bats perceive echo delay with an accuracy of 10-15 ns and have two-echo resolution of about 2 microsecond(s) . Moreover, bats perceive echo phase-shifts as the correctly corresponding shifts in echo delay. Successive images are subtracted to enhance perception of shape from multiple 'looks', and echo phase is an integral part of this critical process. Utterly novel time-scale magnification appears in the bat's neural responses to ultrasonic broadcasts and echoes, with time-stretch factors of roughly 10 to 100 that account for the bat's mysteriously high temporal acuity. Bats reconstruct time-domain features of FM broadcasts and echoes in a compact, distributed format that incorporates delay, phase, glint separation, and inter-ear delay differences along the same image dimension.

  1. Acoustics

    NASA Technical Reports Server (NTRS)

    Goodman, Jerry R.; Grosveld, Ferdinand

    2007-01-01

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

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

    E-print Network

    Zotkin, Dmitry N.

    IMAGING CONCERT HALL ACOUSTICS USING VISUAL AND AUDIO CAMERAS Adam O'Donovan, Ramani Duraiswami, acoustical scene analysis. 1. INTRODUCTION Human listening enjoyment and our ability to localize sound and measurements/simulation to assure that the room acoustics helps the perception of the performance rather than

  3. Acoustic micro-Doppler radar for human gait imaging.

    PubMed

    Zhang, Zhaonian; Pouliquen, Philippe O; Waxman, Allen; Andreou, Andreas G

    2007-03-01

    A portable acoustic micro-Doppler radar system for the acquisition of human gait signatures in indoor and outdoor environments is reported. Signals from an accelerometer attached to the leg support the identification of the components in the measured micro-Doppler signature. The acoustic micro-Doppler system described in this paper is simpler and offers advantages over the widely used electromagnetic wave micro-Doppler radars. PMID:17407918

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

    PubMed Central

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

    2013-01-01

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

  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. Liver reserve function assessment by acoustic radiation force impulse imaging

    PubMed Central

    Sun, Xiao-Lan; Liang, Li-Wei; Cao, Hui; Men, Qiong; Hou, Ke-Zhu; Chen, Zhen; Zhao, Ya-E

    2015-01-01

    AIM: To evaluate the utility of liver reserve function by acoustic radiation force impulse (ARFI) imaging in patients with liver tumors. METHODS: Seventy-six patients with liver tumors were enrolled in this study. Serum biochemical indexes, such as aminotransferase (ALT), aspartate aminotransferase (AST), serum albumin (ALB), total bilirubin (T-Bil), and other indicators were observed. Liver stiffness (LS) was measured by ARFI imaging, measurements were repeated 10 times, and the average value of the results was taken as the final LS value. Indocyanine green (ICG) retention was performed, and ICG-K and ICG-R15 were recorded. Child-Pugh (CP) scores were carried out based on patients preoperative biochemical tests and physical condition. Correlations among CP scores, ICG-R15, ICG-K and LS values were observed and analyzed using either the Pearson correlation coefficient or the Spearman rank correlation coefficient. Kruskal-Wallis test was used to compare LS values of CP scores, and the receiver-operator characteristic (ROC) curve was used to analyze liver reserve function assessment accuracy. RESULTS: LS in the ICG-R15 10%-20% group was significantly higher than in the ICG-R15 < 10% group; and the difference was statistically significant (2.19 0.27 vs 1.59 0.32, P < 0.01). LS in the ICG-R15 > 20% group was significantly higher than in the ICG-R15 < 10% group; and the difference was statistically significant (2.92 0.29 vs 1.59 0.32, P < 0.01). The LS value in patients with CP class A was lower than in patients with CP class B (1.57 0.34 vs 1.86 0.27, P < 0.05), while the LS value in patients with CP class B was lower than in patients with CP class C (1.86 0.27 vs 2.47 0.33, P < 0.01). LS was positively correlated with ICG-R15 (r = 0.617, P < 0.01) and CP score (r = 0.772, P < 0.01). Meanwhile, LS was negatively correlated with ICG-K (r = -0.673, P < 0.01). AST, ALT and T-Bil were positively correlated with LS, while ALB was negatively correlated with LS (P < 0.05). The ROC curve revealed that the when the LS value was 2.34 m/s, the Youden index was at its highest point, sensitivity was 69.2% and specificity was 92.1%. CONCLUSION: For patients with liver tumors, ARFI imaging is a useful tool for assessing liver reserve function. PMID:26327773

  8. Tonpilz piezoelectric transducers with acoustic matching plates for underwater color image transmission.

    PubMed

    Inoue, T; Nada, T; Tsuchiya, T; Nakanishi, T; Miyama, T; Konno, M

    1993-01-01

    Tonpilz piezoelectric transducers with multiple acoustic matching plates are suitable for color image acoustic transmission, to achieve wideband low-ripple characteristics as well as high-efficiency high-power transmitting capability. The design method for the transducers was investigated on the basis of multiple-mode filter synthesis theory. For transducers with single, double, and triple matching plates, optimum specific acoustic impedances and lengths were calculated. Moreover, based on this design method, a 24 kHz array comprising nine identical transducers with single matching plates was built and evaluated. As a result, this array showed high-efficiency, low-ripple, and wideband characteristics. Excellent agreement between theoretical values and experimental results was obtained. A field test was carried out on color image transmission from a 3500 m sea depth, using the fabricated array, during which good color images were received. PMID:18263165

  9. 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.

  10. 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.

  11. NOTE: Acoustical properties of selected tissue phantom materials for ultrasound imaging

    NASA Astrophysics Data System (ADS)

    Zell, K.; Sperl, J. I.; Vogel, M. W.; Niessner, R.; Haisch, C.

    2007-10-01

    This note summarizes the characterization of the acoustic properties of four materials intended for the development of tissue, and especially breast tissue, phantoms for the use in photoacoustic and ultrasound imaging. The materials are agar, silicone, polyvinyl alcohol gel (PVA) and polyacrylamide gel (PAA). The acoustical properties, i.e., the speed of sound, impedance and acoustic attenuation, are determined by transmission measurements of sound waves at room temperature under controlled conditions. Although the materials are tested for application such as photoacoustic phantoms, we focus here on the acoustic properties, while the optical properties will be discussed elsewhere. To obtain the acoustic attenuation in a frequency range from 4 MHz to 14 MHz, two ultrasound sources of 5 MHz and 10 MHz core frequencies are used. For preparation, each sample is cast into blocks of three different thicknesses. Agar, PVA and PAA show similar acoustic properties as water. Within silicone polymer, a significantly lower speed of sound and higher acoustical attenuation than in water and human tissue were found. All materials can be cast into arbitrary shapes and are suitable for tissue-mimicking phantoms. Due to its lower speed of sound, silicone is generally less suitable than the other presented materials.

  12. 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.

  13. 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.

  14. 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.

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

    E-print Network

    Wagner, Oliver

    , Ontario, Canada comprise 62 papers including topics of: Biological and Medical, Nondestructive Testing.E. Green Jr. A Brief History of Medical Ultrasonics; J.P. Jones. Developments of Ultrasonic Measurement; R.M. Schmitt. History of Acoustical Imaging: A Brief Review of the early days of Ultrasonic QNDE

  16. 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

  17. A simple and exact acoustic wavefield modelling code for data processing, imaging and interferometry applications

    E-print Network

    that numerical errors due to wavefield modelling are reduced to a minimum. We present a new MATLAB code basedA simple and exact acoustic wavefield modelling code for data processing, imaging of its implementation. We also benchmark the code against a good finite-difference code. As our Foldy

  18. Constant-beamwidth and constant-powerwidth wideband robust Capon beamformers for acoustic imaging

    NASA Astrophysics Data System (ADS)

    Wang, Zhisong; Li, Jian; Stoica, Petre; Nishida, Toshikazu; Sheplak, Mark

    2004-09-01

    The standard Capon beamformer (SCB) is sensitive to the mismatch between the assumed and actual array steering vector, which occurs often in practice. Recently a robust Capon beamformer (RCB) was proposed by extending the SCB to the case of uncertain array steering vectors. In certain applications such as acoustic imaging, it is desirable that the beamwidth is constant across the frequency bins. This prevents future corrections for different frequencies and contributes to consistent sound pressure level (SPL) estimation, which means that for an acoustic wideband monopole source with a flat spectrum the acoustic image for each frequency bin stays the same. However, the beamwidth of RCB decreases with frequency, which can lead to inconsistent imaging results across the frequencies. In this paper two beamformers are proposed, namely a constant-beamwidth robust Capon beamformer (CBRCB) and a constant-powerwidth robust Capon beamformer (CPRCB), as extensions of RCB for consistent wideband acoustic imaging. Both CBRCB and CPRCB are more robust against array steering vector errors and finite sample size problems than SCB and have better resolution and interference suppression capability than data-independent beamformers. Moreover, they both can be efficiently implemented. The effectiveness of CBRCB and CPRCB is demonstrated via a number of simulated and experimental examples.

  19. Acoustic investigation of microbubble response to medical imaging ultrasound pulses

    E-print Network

    Thomas, David H.

    2010-01-01

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

  20. 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.

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

    PubMed Central

    Nicolas, Jan-David; Reusch, Tobias; Osterhoff, Markus; Sprung, Michael; Schlein, 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

  2. 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.

  3. 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.

  4. 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.

  5. 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

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

    SciTech Connect

    Xiong, Jichuan; Xu, Xiaodong E-mail: christ.glorieux@fys.kuleuven.be; Glorieux, Christ E-mail: christ.glorieux@fys.kuleuven.be; Matsuda, Osamu; Cheng, Liping

    2015-05-15

    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.

  7. Fast photoacoustic imaging with a line scanning optical-acoustical resolution photoacoustic microscope (LS-OAR-PAM)

    NASA Astrophysics Data System (ADS)

    Nuster, Robert; Paltauf, Guenther

    2015-07-01

    We present the concept, the setup and a preliminary experiment using optical ultrasound detection with a CCD camera combined with focused line excitation for photoacoustic microscopy. The line scanning optical-acoustical resolution photoacoustic microscope (LS-OAR-PAM) with optical ultrasound detection is capable of real-time B-scan imaging providing acoustical resolution within the individual B-scans and optical out of plane resolution up to a depth limited by optical diffusion. A 3D image is composed of reconstructed B-scan images recorded while scanning the excitation line along the sample surface. Proof of concept is shown by imaging a phantom containing black human hairs and carbon fibers. The obtained C-scan image clearly shows the different resolution in the two perpendicular directions, namely diffraction limited by optical focusing in scan direction and acoustically limited in direction parallel to line orientation by the properties of acoustic wave propagation.

  8. 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.; Blodgett, M. P.

    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.

  9. Modern Techniques in Acoustical Signal and Image Processing

    SciTech Connect

    Candy, J V

    2002-04-04

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

  10. 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.

  11. Three dimensional full-wave nonlinear acoustic simulations: Applications to ultrasound imaging

    NASA Astrophysics Data System (ADS)

    Pinton, Gianmarco

    2015-10-01

    Characterization of acoustic waves that propagate nonlinearly in an inhomogeneous medium has significant applications to diagnostic and therapeutic ultrasound. The generation of an ultrasound image of human tissue is based on the complex physics of acoustic wave propagation: diffraction, reflection, scattering, frequency dependent attenuation, and nonlinearity. The nonlinearity of wave propagation is used to the advantage of diagnostic scanners that use the harmonic components of the ultrasonic signal to improve the resolution and penetration of clinical scanners. One approach to simulating ultrasound images is to make approximations that can reduce the physics to systems that have a low computational cost. Here a maximalist approach is taken and the full three dimensional wave physics is simulated with finite differences. This paper demonstrates how finite difference simulations for the nonlinear acoustic wave equation can be used to generate physically realistic two and three dimensional ultrasound images anywhere in the body. A specific intercostal liver imaging scenario for two cases: with the ribs in place, and with the ribs removed. This configuration provides an imaging scenario that cannot be performed in vivo but that can test the influence of the ribs on image quality. Several imaging properties are studied, in particular the beamplots, the spatial coherence at the transducer surface, the distributed phase aberration, and the lesion detectability for imaging at the fundamental and harmonic frequencies. The results indicate, counterintuitively, that at the fundamental frequency the beamplot improves due to the apodization effect of the ribs but at the same time there is more degradation from reverberation clutter. At the harmonic frequency there is significantly less improvement in the beamplot and also significantly less degradation from reverberation. It is shown that even though simulating the full propagation physics is computationally challenging it is necessary to quantify ultrasound image quality and its sources of degradation.

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

    NASA Astrophysics Data System (ADS)

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

    2011-06-01

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

  13. 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.

  14. Resolution estimation and bias reduction in acoustic radiation force impulse imaging

    NASA Astrophysics Data System (ADS)

    Menon, Manoj G.

    Pathological conditions give rise to mechanical changes in tissue that can be exploited for the purpose of diagnosis and treatment of disease. Elasticity imaging is a field developed to creating images of tissue stiffness by mechanically exciting tissue and tracking the tissue response. Acoustic Radiation Force Impulse (ARFI) imaging is one such modality that measures the micron-scale displacements induced in tissue by local acoustic radiation forces using a high intensity ultrasound pulses generated by a standard diagnostic ultrasound scanner. Ultrasound pulses track displacements that are quantified using conventional correlation-based speckle-tracking methods. Generated displacement images can exhibit improved contrast of diseased tissue than conventional ultrasound techniques. In this thesis, the spatial resolution limits of ARFI imaging have been measured using novel simulation and experimental techniques. The full-width, half-maximum (FWHM) of the point-spread function (PSF), a measure of the resolution limit of an imaging system, was extracted by imaging a tissue-mimicking phantom composed of two bonded materials. The ARFI image of the material interface was an estimate of the step response of the system. The ARFI imaging resolution limit was further explored using FEM/acoustic field simulations and linear shift invariant (LSI) models. The ARFI imaging resolution limit was submillimeter, but was highly dependent on imaging parameters. ARFI axial resolution was limited by the correlation window length and tracking pulse parameters. When the correlation window length was less than 1 mm, FEM and LSI models suggest the mechanical response of the tissue influences the resolution, resulting in a larger FWHM than would be predicted by imaging and signal processing parameters alone. ARFI lateral resolution limit corresponded to the lateral two-way beamwidth of the tracking beam. Measuring ARFI imaging resolution capabilities on small phantom inclusions and tissue ablation lesions proved the validity of the step-response based estimated resolution limits on objects of relevant, circular geometry. ARFI imaging resolution was again primarily a function of imaging and signal processing parameters, in good agreement with modulus step phantom derived results. To improve the ability of ARFI imaging to resolve targets near bright boundaries, a method called envelope weighted normalization (EWN) was developed to reduce amplitude modulation of ultrasound signals, thereby reducing displacement estimation bias.

  15. Methods And Systems For Using Reference Images In Acoustic Image Processing

    DOEpatents

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

    2005-01-04

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

  16. Imaging textural variation in the acoustoelastic coefficient of aluminum using surface acoustic waves.

    PubMed

    Ellwood, R; Stratoudaki, T; Sharples, S D; Clark, M; Somekh, M G

    2015-11-01

    Much interest has arisen in nonlinear acoustic techniques because of their reported sensitivity to variations in residual stress, fatigue life, and creep damage when compared to traditional linear ultrasonic techniques. However, there is also evidence that the nonlinear acoustic properties are also sensitive to material microstructure. As many industrially relevant materials have a polycrystalline structure, this could potentially complicate the monitoring of material processes when using nonlinear acoustics. Variations in the nonlinear acoustoelastic coefficient on the same length scale as the microstructure of a polycrystalline sample of aluminum are investigated in this paper. This is achieved by the development of a measurement protocol that allows imaging of the acoustoelastic response of a material across a samples surface at the same time as imaging the microstructure. The development, validation, and limitations of this technique are discussed. The nonlinear acoustic response is found to vary spatially by a large factor (>20) between different grains. A relationship is observed when the spatial variation of the acoustoelastic coefficient is compared to the variation in material microstructure. PMID:26627757

  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.

    2001-01-31

    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.

  18. Acoustic Reciprocity of Spatial Coherence in Ultrasound Imaging

    PubMed Central

    Bottenus, Nick; stner, 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 SC2000ultrasound 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

  19. An Objective Focussing Measure for Acoustically Obtained Images

    NASA Astrophysics Data System (ADS)

    Czarnecki, Krzysztof; Moszy?ski, Marek; Rojewski, Miros?aw

    In scientific literature many parameters of an image sharpness can be defined, that can be used for the evaluation of display energy concentration (EC). This paper proposes a new, simple approach to EC quantitative evaluation in spectrograms, which are used for the analysis and visualization of sonar signals. The presented approach of the global-image EC measure was developed to the evaluation of EC in arbitrary direction (or at an arbitrary angle) and along an arbitrary path that is contained within the displayed area. The proposed measures were used to establish optimum spectrograph parameters, subject to high EC in images, in particular the type and width of the window. Moreover, the paper defines the marginal EC distributions that can be used in sonar signal detection as a support to the main detector.

  20. 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

  1. Near-Field Imaging with Sound: An Acoustic STM Model

    ERIC Educational Resources Information Center

    Euler, Manfred

    2012-01-01

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

  2. Underwater Acoustic Matched Field Imaging Based on Compressed Sensing.

    PubMed

    Yan, Huichen; Xu, Jia; Long, Teng; Zhang, Xudong

    2015-01-01

    Matched field processing (MFP) is an effective method for underwater target imaging and localizing, but its performance is not guaranteed due to the nonuniqueness and instability problems caused by the underdetermined essence of MFP. By exploiting the sparsity of the targets in an imaging area, this paper proposes a compressive sensing MFP (CS-MFP) model from wave propagation theory by using randomly deployed sensors. In addition, the model's recovery performance is investigated by exploring the lower bounds of the coherence parameter of the CS dictionary. Furthermore, this paper analyzes the robustness of CS-MFP with respect to the displacement of the sensors. Subsequently, a coherence-excluding coherence optimized orthogonal matching pursuit (CCOOMP) algorithm is proposed to overcome the high coherent dictionary problem in special cases. Finally, some numerical experiments are provided to demonstrate the effectiveness of the proposed CS-MFP method. PMID:26457708

  3. Underwater Acoustic Matched Field Imaging Based on Compressed Sensing

    PubMed Central

    Yan, Huichen; Xu, Jia; Long, Teng; Zhang, Xudong

    2015-01-01

    Matched field processing (MFP) is an effective method for underwater target imaging and localizing, but its performance is not guaranteed due to the nonuniqueness and instability problems caused by the underdetermined essence of MFP. By exploiting the sparsity of the targets in an imaging area, this paper proposes a compressive sensing MFP (CS-MFP) model from wave propagation theory by using randomly deployed sensors. In addition, the models recovery performance is investigated by exploring the lower bounds of the coherence parameter of the CS dictionary. Furthermore, this paper analyzes the robustness of CS-MFP with respect to the displacement of the sensors. Subsequently, a coherence-excluding coherence optimized orthogonal matching pursuit (CCOOMP) algorithm is proposed to overcome the high coherent dictionary problem in special cases. Finally, some numerical experiments are provided to demonstrate the effectiveness of the proposed CS-MFP method. PMID:26457708

  4. Applications of stereoscopic particle image velocimetry: Dust acoustic waves and velocity space distribution functions

    SciTech Connect

    Thomas, Edward Jr.; Williams, Jeremiah

    2006-05-15

    Two-dimensional particle image velocimetry (2D-PIV) techniques have been applied to dusty plasmas for the past 5 years. During that time, 2D-PIV has been used to provide detailed measurements of microparticle transport in dusty plasmas. However, a measurement of the third velocity vector direction is necessary to fully understand the microparticle transport. In this paper, stereoscopic particle image velocimetry (stereo-PIV) is used as a technique for obtaining all three-velocity vector components. This paper discusses the application of stereo-PIV techniques to measurements of dust acoustic waves and velocity space distribution functions in dusty plasmas.

  5. Hepatic Steatosis: Assessment with Acoustic Structure Quantification of US Imaging.

    PubMed

    Son, Jee-Young; Lee, Jae Young; Yi, Nam-Joon; Lee, Kwang-Woong; Suh, Kyung-Suk; Kim, Kwang Gi; Lee, Jeong Min; Han, Joon Koo; Choi, Byung Ihn

    2016-01-01

    Purpose To investigate the diagnostic performance of acoustic structure quantification (ASQ) for the assessment of hepatic steatosis by using hydrogen 1 ((1)H) magnetic resonance (MR) spectroscopy as the reference standard and to compare ASQ with hepatorenal ratio. Materials and Methods This prospective study was approved by an institutional review board, and informed written consent was obtained from all participants. ASQ and MR spectroscopy were performed in 89 participants (mean age, 41.48 years 14.16; 35 men, 54 women) without history of chronic liver disease. Obtained were focal disturbance (FD) ratio by using ASQ, hepatic fat fraction (HFF) by using MR spectroscopy, and hepatorenal ratio by using a histogram. Correlation coefficient, intraclass correlation coefficient, and receiver operating curve analyses were performed. Results FD ratio measured with ASQ had a strong linear correlation with HFF measured with MR spectroscopy after logarithmic transformation of both variables (r = -0.87; P < .001). By using HFF of 5.79% as a cutoff value of 10% hepatic steatosis, 29 of 89 participants (32.6%) were categorized into the group with hepatic steatosis of 10% or greater (mean HFF, 13.18% 4.89). The area under curve of the FD ratio for diagnosing hepatic steatosis 10% or greater was 0.959 (95% confidence interval: 0.895, 0.990) with sensitivity of 86.2% (95% confidence interval: 68.3%, 96.0%) and specificity of 100% (95% confidence interval: 94.0%, 100.0%) by using a cutoff value of 0.1; the area under curve and specificity of the FD ratio were significantly higher than those of the hepatorenal ratio (respectively, 0.772 and 73.3%; respective P values, .001 and <.001). Conclusion This pilot study in a cohort of patients with hepatic steatosis without other parenchymal disease suggested ASQ may be valuable for the quantification of hepatic steatosis and detection of hepatic steatosis 10% or greater in living liver donors. () RSNA, 2015. PMID:26121121

  6. Acoustic property reconstruction of a pygmy sperm whale (Kogia breviceps) forehead based on computed tomography imaging.

    PubMed

    Song, Zhongchang; Xu, Xiao; Dong, Jianchen; Xing, Luru; Zhang, Meng; Liu, Xuecheng; Zhang, Yu; Li, Songhai; Berggren, Per

    2015-11-01

    Computed tomography (CT) imaging and sound experimental measurements were used to reconstruct the acoustic properties (density, velocity, and impedance) of the forehead tissues of a deceased pygmy sperm whale (Kogia breviceps). The forehead was segmented along the body axis and sectioned into cross section slices, which were further cut into sample pieces for measurements. Hounsfield units (HUs) of the corresponding measured pieces were obtained from CT scans, and regression analyses were conducted to investigate the linear relationships between the tissues' HUs and velocity, and HUs and density. The distributions of the acoustic properties of the head at axial, coronal, and sagittal cross sections were reconstructed, revealing that the nasal passage system was asymmetric and the cornucopia-shaped spermaceti organ was in the right nasal passage, surrounded by tissues and airsacs. A distinct dense theca was discovered in the posterior-dorsal area of the melon, which was characterized by low velocity in the inner core and high velocity in the outer region. Statistical analyses revealed significant differences in density, velocity, and acoustic impedance between all four structures, melon, spermaceti organ, muscle, and connective tissue (p?acoustic properties of the forehead tissues provide important information for understanding the species' bioacoustic characteristics. PMID:26627786

  7. A comparison of traffic estimates of nocturnal flying animals using radar, thermal imaging, and acoustic recording.

    PubMed

    Horton, Kyle G; Shriver, W Gregory; Buler, Jeffrey J

    2015-03-01

    There are several remote-sensing tools readily available for the study of nocturnally flying animals (e.g., migrating birds), each possessing unique measurement biases. We used three tools (weather surveillance radar, thermal infrared camera, and acoustic recorder) to measure temporal and spatial patterns of nocturnal traffic estimates of flying animals during the spring and fall of 2011 and 2012 in Lewes, Delaware, USA. Our objective was to compare measures among different technologies to better understand their animal detection biases. For radar and thermal imaging, the greatest observed traffic rate tended to occur at, or shortly after, evening twilight, whereas for the acoustic recorder, peak bird flight-calling activity was observed just prior to morning twilight. Comparing traffic rates during the night for all seasons, we found that mean nightly correlations between acoustics and the other two tools were weakly correlated (thermal infrared camera and acoustics, r = 0.004 0.04 SE, n = 100 nights; radar and acoustics, r = 0.14 0.04 SE, n = 101 nights), but highly variable on an individual nightly basis (range = -0.84 to 0.92, range = -0.73 to 0.94). The mean nightly correlations between traffic rates estimated by radar and by thermal infrared camera during the night were more strongly positively correlated (r = 0.39 0.04 SE, n = 125 nights), but also were highly variable for individual nights (range = -0.76 to 0.98). Through comparison with radar data among numerous height intervals, we determined that flying animal height above the ground influenced thermal imaging positively and flight call detections negatively. Moreover, thermal imaging detections decreased with the presence of cloud cover and increased with mean ground flight speed of animals, whereas acoustic detections showed no relationship with cloud cover presence but did decrease with increased flight speed. We found sampling methods to be positively correlated when comparing mean nightly traffic rates across nights. The strength of these correlations generally increased throughout the night, peaking 2-3 hours before morning twilight. Given the convergence of measures by different tools at this time, we suggest that researchers consider sampling flight activity in the hours before morning twilight when differences due to detection biases among sampling tools appear to be minimized. PMID:26263662

  8. The development and potential of acoustic radiation force impulse (ARFI) imaging for carotid artery plaque characterization.

    PubMed

    Allen, Jason D; Ham, Katherine L; Dumont, Douglas M; Sileshi, Bantayehu; Trahey, Gregg E; Dahl, Jeremy J

    2011-08-01

    Stroke is the third leading cause of death and long-term disability in the USA. Currently, surgical intervention decisions in asymptomatic patients are based upon the degree of carotid artery stenosis. While there is a clear benefit of endarterectomy for patients with severe (> 70%) stenosis, in those with high/moderate (50-69%) stenosis the evidence is less clear. Evidence suggests ischemic stroke is associated less with calcified and fibrous plaques than with those containing softer tissue, especially when accompanied by a thin fibrous cap. A reliable mechanism for the identification of individuals with atherosclerotic plaques which confer the highest risk for stroke is fundamental to the selection of patients for vascular interventions. Acoustic radiation force impulse (ARFI) imaging is a new ultrasonic-based imaging method that characterizes the mechanical properties of tissue by measuring displacement resulting from the application of acoustic radiation force. These displacements provide information about the local stiffness of tissue and can differentiate between soft and hard areas. Because arterial walls, soft tissue, atheromas, and calcifications have a wide range in their stiffness properties, they represent excellent candidates for ARFI imaging. We present information from early phantom experiments and excised human limb studies to in vivo carotid artery scans and provide evidence for the ability of ARFI to provide high-quality images which highlight mechanical differences in tissue stiffness not readily apparent in matched B-mode images. This allows ARFI to identify soft from hard plaques and differentiate characteristics associated with plaque vulnerability or stability. PMID:21447606

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

    E-print Network

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

    2013-01-01

    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...

  10. 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. SRASspatially resolved acoustic spectroscopyis 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.

  11. Eigenfunction analysis of stochastic backscatter for characterization of acoustic aberration in medical ultrasound imaging

    NASA Astrophysics Data System (ADS)

    Varslot, Trond; Krogstad, Harald; Mo, Eirik; Angelsen, Bjrn A.

    2004-06-01

    Presented here is a characterization of aberration in medical ultrasound imaging. The characterization is optimal in the sense of maximizing the expected energy in a modified beamformer output of the received acoustic backscatter. Aberration correction based on this characterization takes the form of an aberration correction filter. The situation considered is frequently found in applications when imaging organs through a body wall: aberration is introduced in a layer close to the transducer, and acoustic backscatter from a scattering region behind the body wall is measured at the transducer surface. The scattering region consists of scatterers randomly distributed with very short correlation length compared to the acoustic wavelength of the transmit pulse. The scatterer distribution is therefore assumed to be ? correlated. This paper shows how maximizing the expected energy in a modified beamformer output signal naturally leads to eigenfunctions of a Fredholm integral operator, where the associated kernel function is a spatial correlation function of the received stochastic signal. Aberration characterization and aberration correction are presented for simulated data constructed to mimic aberration introduced by the abdominal wall. The results compare well with what is obtainable using data from a simulated point source.

  12. Symmetry analysis for nonlinear time reversal methods applied to nonlinear acoustic imaging

    NASA Astrophysics Data System (ADS)

    Dos Santos, Serge; Chaline, Jennifer

    2015-10-01

    Using symmetry invariance, nonlinear Time Reversal (TR) and reciprocity properties, the classical NEWS methods are supplemented and improved by new excitations having the intrinsic property of enlarging frequency analysis bandwidth and time domain scales, with now both medical acoustics and electromagnetic applications. The analysis of invariant quantities is a well-known tool which is often used in nonlinear acoustics in order to simplify complex equations. Based on a fundamental physical principle known as symmetry analysis, this approach consists in finding judicious variables, intrinsically scale dependant, and able to describe all stages of behaviour on the same theoretical foundation. Based on previously published results within the nonlinear acoustic areas, some practical implementation will be proposed as a new way to define TR-NEWS based methods applied to NDT and medical bubble based non-destructive imaging. This paper tends to show how symmetry analysis can help us to define new methodologies and new experimental set-up involving modern signal processing tools. Some example of practical realizations will be proposed in the context of biomedical non-destructive imaging using Ultrasound Contrast Agents (ACUs) where symmetry and invariance properties allow us to define a microscopic scale-invariant experimental set-up describing intrinsic symmetries of the microscopic complex system.

  13. Resonant acoustic nonlinearity for defect-selective imaging and NDT

    NASA Astrophysics Data System (ADS)

    Solodov, Igor

    2015-10-01

    The bottleneck problem of nonlinear NDT is a low efficiency of conversion from fundamental frequency to nonlinear frequency components. In this paper, it is proposed to use a combination of mechanical resonance and nonlinearity of defects to enhance the input-output conversion. The concept of the defect as a nonlinear oscillator brings about new dynamic and frequency scenarios characteristic of parametric oscillations. The modes observed in experiment include sub- and superharmonic resonances with anomalously efficient generation of the higher harmonics and subharmonics. A modified version of the superharmonic resonance (combination frequency resonance) is used to enhance the efficiency of frequency mixing mode of nonlinear NDT. All the resonant nonlinear modes are strongly localized in the defect area that provides a background for high-contrast highly-sensitive defect- and frequency-selective imaging.

  14. 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.

  15. 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.

  16. 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.

  17. Sensing the delivery and endocytosis of nanoparticles using magneto-photo-acoustic imaging

    PubMed Central

    Qu, M.; Mehrmohammadi, M.; Emelianov, S.Y.

    2015-01-01

    Many biomedical applications necessitate a targeted intracellular delivery of the nanomaterial to specific cells. Therefore, a non-invasive and reliable imaging tool is required to detect both the delivery and cellular endocytosis of the nanoparticles. Herein, we demonstrate that magneto-photo-acoustic (MPA) imaging can be used to monitor the delivery and to identify endocytosis of magnetic and optically absorbing nanoparticles. The relationship between photoacoustic (PA) and magneto-motive ultrasound (MMUS) signals from the in vitro samples were analyzed to identify the delivery and endocytosis of nanoparticles. The results indicated that during the delivery of nanoparticles to the vicinity of the cells, both PA and MMUS signals are almost linearly proportional. However, accumulation of nanoparticles within the cells leads to nonlinear MMUS-PA relationship, due to non-linear MMUS signal amplification. Therefore, through longitudinal MPA imaging, it is possible to monitor the delivery of nanoparticles and identify the endocytosis of the nanoparticles by living cells. PMID:26640773

  18. Normal Values in Healthy Liver in Central India by Acoustic Radiation Force Impulse Imaging

    PubMed Central

    Raghuwanshi, Babita; Jain, Niti; Jain, Manish

    2013-01-01

    Aim: The aim of this study was to reliably measure and define the normal wave velocity values in a healthy liver by Acoustic radiation force impulse imaging (ARFI) technology in central India. Subjects and Methods: Fifty two healthy volunteers underwent acoustic radiation force impulse imaging tissue quantification and were enrolled in this prospective study. All patients were examined clinically by a clinician and blood samples were drawn and tested for liver function test and viral markers for hepatitis B virus, hepatitis C virus. The healthy volunteers were then examined by a certified sonologist and twenty-four measurements per subject were obtained and evaluations were performed. Statistical comparison of all mean data was performed with Students t-test was done. A valueof p < 0.05 was considered significant. A comparative analysis was performed, and interclasscorrelation coefficients were calculated. Results: The sonologist obtained 416 measurements. A statistically significant differencewas found between the mean shear wave velocity values in deep of the right lobe of the liver and the values obtained on the surface of the right lobe (1.2vs1.05 m/s) and between the mean values obtained deep in the right lobe and those obtained deep in the left lobe (1.2vs 1.0 m/s). In almost all cases, the shear wave speeds were between 1 and 2 m/s. Conclusion: Acoustic radiation force impulse imaging quantification of hepatic tissue is more reproducible when applied to the deeper portion of the right lobe of the liver. PMID:24392382

  19. Reconstruction of an acoustic pressure field in a resonance tube by particle image velocimetry.

    PubMed

    Kuzuu, K; Hasegawa, S

    2015-11-01

    A technique for estimating an acoustic field in a resonance tube is suggested. The estimation of an acoustic field in a resonance tube is important for the development of the thermoacoustic engine, and can be conducted employing two sensors to measure pressure. While this measurement technique is known as the two-sensor method, care needs to be taken with the location of pressure sensors when conducting pressure measurements. In the present study, particle image velocimetry (PIV) is employed instead of a pressure measurement by a sensor, and two-dimensional velocity vector images are extracted as sequential data from only a one- time recording made by a video camera of PIV. The spatial velocity amplitude is obtained from those images, and a pressure distribution is calculated from velocity amplitudes at two points by extending the equations derived for the two-sensor method. By means of this method, problems relating to the locations and calibrations of multiple pressure sensors are avoided. Furthermore, to verify the accuracy of the present method, the experiments are conducted employing the conventional two-sensor method and laser Doppler velocimetry (LDV). Then, results by the proposed method are compared with those obtained with the two-sensor method and LDV. PMID:26627789

  20. Frame Rate Considerations for Real-Time Abdominal Acoustic Radiation Force Impulse Imaging

    PubMed Central

    Fahey, Brian J.; Palmeri, Mark L.; Trahey, Gregg E.

    2008-01-01

    With the advent of real-time Acoustic Radiation Force Impulse (ARFI) imaging, elevated frame rates are both desirable and relevant from a clinical perspective. However, fundamental limitations on frame rates are imposed by thermal safety concerns related to incident radiation force pulses. Abdominal ARFI imaging utilizes a curvilinear scanning geometry that results in markedly different tissue heating patterns than those previously studied for linear arrays or mechanically-translated concave transducers. Finite Element Method (FEM) models were used to simulate these tissue heating patterns and to analyze the impact of tissue heating on frame rates available for abdominal ARFI imaging. A perfusion model was implemented to account for cooling effects due to blood flow and frame rate limitations were evaluated in the presence of normal, reduced and negligible tissue perfusions. Conventional ARFI acquisition techniques were also compared to ARFI imaging with parallel receive tracking in terms of thermal efficiency. Additionally, thermocouple measurements of transducer face temperature increases were acquired to assess the frame rate limitations imposed by cumulative heating of the imaging array. Frame rates sufficient for many abdominal imaging applications were found to be safely achievable utilizing available ARFI imaging techniques. PMID:17521042

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

    PubMed Central

    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 porpoises 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 porpoises 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 Cuviers 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 porpoises melon. PMID:25856588

  2. Imaging of a patterned and buried molecular layer by coherent acoustic phonon spectroscopy

    NASA Astrophysics Data System (ADS)

    Hettich, Mike; Jacob, Karl; Ristow, Oliver; He, Chuan; Mayer, Jan; Schubert, Martin; Gusev, Vitalyi; Bruchhausen, Axel; Dekorsy, Thomas

    2012-11-01

    A molecular layer of aminopropyltriethoxysilane is patterned with a focused ion beam and subsequently covered by a gold film. The gold-polymer-substrate structures are afterwards imaged by ultrafast coherent acoustic phonon spectroscopy in reflection geometry. We demonstrate that the lateral structure of the covered polymer layer can be detected via the damping time of the vibrational mode of the gold film. Furthermore, we utilize Brillouin oscillations originating from the silicon substrate to map the structures and to estimate the molecular layer thickness.

  3. Investigating the emotional response to room acoustics: A functional magnetic resonance imaging study.

    PubMed

    Lawless, M S; Vigeant, M C

    2015-10-01

    While previous research has demonstrated the powerful influence of pleasant and unpleasant music on emotions, the present study utilizes functional magnetic resonance imaging (fMRI) to assess the positive and negative emotional responses as demonstrated in the brain when listening to music convolved with varying room acoustic conditions. During fMRI scans, subjects rated auralizations created in a simulated concert hall with varying reverberation times. The analysis detected activations in the dorsal striatum, a region associated with anticipation of reward, for two individuals for the highest rated stimulus, though no activations were found for regions associated with negative emotions in any subject. PMID:26520354

  4. Comparison of the Reliability of Acoustic Radiation Force Impulse Imaging and Supersonic Shear Imaging in Measurement of Liver Stiffness.

    PubMed

    Woo, Hyunsik; Lee, Jae Young; Yoon, Jeong Hee; Kim, Won; Cho, Belong; Choi, Byung Ihn

    2015-12-01

    Purpose To compare the reliability of acoustic radiation force impulse (ARFI) imaging and supersonic shear imaging (SSI) in measurement of liver stiffness. Materials and Methods This study was approved by the institutional review board, and written informed consent was obtained for all patients. Seventy-nine patients (25 healthy patients, 26 with Child-Pugh class A, and 28 with Child-Pugh class B or C) were enrolled and analyzed from April 2012 to April 2013. In each patient, three abdominal radiologists performed nine measurements of hepatic shear-wave speed with both ARFI imaging and SSI on the same day. Four weeks later, a second session was performed with the same protocol. Interobserver and intraobserver agreements were calculated by using intraclass correlation coefficients. Technical failures and measurement time were evaluated. Results There were four technical failures in the SSI group and one in the ARFI group (P = .375). The overall interobserver agreement of ARFI imaging was significantly higher than that of SSI (0.941 vs 0.828, P < .001). The overall intraobserver agreement of ARFI imaging was significantly higher than that of SSI (0.915 vs 0.829, P < .001). The overall shear-wave speed measured with SSI was higher than that measured with ARFI imaging (2.04 m/sec 0.88 vs 1.80 m/sec 0.81, P < .001). The measurement time of SSI was longer than that of ARFI imaging (310.8 seconds 88.5 vs 84.5 seconds 15.4, P < .001). Conclusion ARFI imaging was more reliable than SSI in measurement of liver stiffness. The hepatic shear-wave speed measured with SSI was higher than that measured with ARFI imaging, which means that the shear-wave speeds measured with ARFI imaging and SSI cannot be used interchangeably. () RSNA, 2015. PMID:26147680

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

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-04

    ...Section 4(f) Policy Paper that will provide...private historic sites for Federal highway...Section 4(f) Policy Paper was written primarily...private historic sites for Federal highway...Refuges, and Historic Sites,'' were promulgated...Section 4(f) Policy Paper will replace...

  6. 77 FR 321 - Section 4(f) Policy Paper

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-04

    ... Federal Highway Administration Section 4(f) Policy Paper AGENCY: Federal Highway Administration (FHWA... draft Section 4(f) Policy Paper that will provide guidance on the procedures the FHWA will follow when... practicable. Background A copy of the proposed Section 4(f) Policy Paper is available for download and...

  7. A confidence-based approach to enhancing underwater acoustic image formation.

    PubMed

    Murino, V; Trucco, A

    1999-01-01

    This paper describes a flexible technique to enhance the formation of short-range acoustic images so as to improve image quality and facilitate the tasks of subsequent postprocessing methods. The proposed methodology operates as an ideal interface between the signals formed by a focused beamforming technique (i.e., the beam signals) and the related image, whether a two-dimensional (2-D) or three-dimensional (3-D) one. To this end, a reliability measure has been introduced, called confidence, which allows one to perform a rapid examination of the beam signals and is aimed at accurately detecting echoes backscattered from a scene. The confidence-based approach exploits the physics of the process of image formation and generic a priori knowledge of a scene to synthesize model-based signals to be compared with actual backscattered echoes, giving, at the same time, a measure of the reliability of their similarity. The objectives that can be attained by this method can be summarized in a reduction in artifacts due to the lowering of the side-lobe level, a better lateral resolution, a greater accuracy in range determination, a direct estimation of the reliability of the information acquired, thus leading to a higher image quality and hence a better scene understanding. Tests on both simulated and actual data (concerning both 2-D and 3-D images) show the higher efficiency of the proposed confidence-based approach, as compared with more traditional techniques. PMID:18267473

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

    E-print Network

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

    2015-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

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

    PubMed

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

    2015-05-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

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

  12. 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.

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

    SciTech Connect

    Kaneko, Shogo; Tomoda, Motonobu; Matsuda, Osamu

    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.

  14. 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.

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

    PubMed Central

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

    2012-01-01

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

  16. 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

  17. 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 imagingthe ultrasound brain helmetand 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

  18. 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.

  19. 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

  20. 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.

  1. Damage Detection in Plate Structures Using Sparse Ultrasonic Transducer Arrays and Acoustic Wavefield Imaging

    SciTech Connect

    Michaels, T.E.; Michaels, J.E.; Mi, B.; Ruzzene, M.

    2005-04-09

    A methodology is presented for health monitoring and subsequent inspection of critical structures. Algorithms have been developed to detect and approximately locate damaged regions by analyzing signals recorded from a permanently mounted, sparse array of transducers. Followup inspections of suspected flaw locations are performed using a dual transducer ultrasonic approach where a permanently mounted transducer is the source and an externally scanned transducer is the receiver. Scan results are presented as snapshots of the propagating ultrasonic wavefield radiating out from the attached transducers. This method, referred to here as Acoustic Wavefield Imaging (AWI), provides an excellent visual representation of the interaction of propagating ultrasonic waves with the structure. Pre-flaw and post-flaw ultrasonic waveforms are analyzed from an aluminum plate specimen with artificially induced damage, and the AWI results show the location and spatial extent of all of the defects.

  2. Acoustical cross-talk in row-column addressed 2-D transducer arrays for ultrasound imaging.

    PubMed

    Christiansen, Thomas Lehrmann; Jensen, Jrgen Arendt; Thomsen, Erik Vilain

    2015-12-01

    The acoustical cross-talk in row-column addressed 2-D transducer arrays for volumetric ultrasound imaging is investigated. Experimental results from a 2.7 MHz, ?/2-pitch capacitive micromachined ultrasonic transducer (CMUT) array with 62 rows and 62 columns are presented and analyzed in the frequency-wavenumber domain. The sources of cross-talk are identified and predicted theoretically. The nearest neighbor cross-talk is -23.93.7 dB when the array is used as a 1-D array with the rows functioning as both transmitters and receivers. In the row-column configuration, with the columns transmitting and the rows receiving, the cross-talk is reduced to -40.23.5 dB. PMID:26216122

  3. A simple and exact acoustic wavefield modeling code for data processing, imaging, and interferometry applications

    E-print Network

    acoustic modeling method and provide examples of its implementation. We also bench- mark the code against algorithms in acoustics or exploration and earth- quake seismology normally requires a synthetic data set

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

    PubMed Central

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

    2013-01-01

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

  5. Direct calculation of 4f3-4f3 transition intensities in Nd3+-doped YPO4 system involving explicit effects of 4f25d configuration

    NASA Astrophysics Data System (ADS)

    Zhang, Jinsu; Liu, Feng; Zhang, Xia; Wang, Xiao-jun; Zhang, Jiahua

    2009-03-01

    The effects of the 4f25d configuration on the intraconfigurational 4\\mathrm {f}^3 \\leftrightarrow 4\\mathrm {f}^3 electric dipole transitions of Nd3+ doped YPO4 are taken into account by a 'direct' calculation. A simple model is applied to analyze the opposite-parity 4f25d configuration admixing into 4f3 transitional states. The matrix elements of the odd-rank crystal-field interaction and the interconfigurational electric dipole transition are directly expressed using a standard tensor operator method. A set of selection rules for f-d mixing and f-f electric dipole transitions is built up. The admixture effect is considered including both explicit 4f25d configuration and other opposite-parity states such as the 4f2n'g configuration which is treated by a closure procedure. Using this calculation method in combination with the experimental data from the absorption spectrum, a set of intensity parameters is obtained. The transition intensities originating from the high-lying 2G9/2(2) level to the lower energy levels are then calculated, demonstrating a good agreement with the experimental results. The new calculation method is suitable for the electric dipole transitions within the 4fN configurations of trivalent lanthanide ions with more than two f-electrons.

  6. Imaging velocity and attenuation anomalies in mining environments using Acoustic Emissions

    NASA Astrophysics Data System (ADS)

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

    2012-04-01

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

  7. In vivo MR acoustic radiation force imaging in the porcine liver

    PubMed Central

    Holbrook, Andrew B.; Ghanouni, Pejman; Santos, Juan M.; Medan, Yoav; Butts Pauly, Kim

    2011-01-01

    Purpose: High intensity focused ultrasound (HIFU) in the abdomen can be sensitive to acoustic aberrations that can exist in the beam path of a single sonication. Having an accurate method to quickly visualize the transducer focus without damaging tissue could assist with executing the treatment plan accurately and predicting these changes and obstacles. By identifying these obstacles, MR acoustic radiation force imaging (MR-ARFI) provides a reliable method for visualizing the transducer focus quickly without damaging tissue and allows accurate execution of the treatment plan. Methods: MR-ARFI was used to view the HIFU focus, using a gated spin echo flyback readout-segmented echo-planar imaging sequence. HIFU spots in a phantom and in the livers of five live pigs under general anesthesia were created with a 550 kHz extracorporeal phased array transducer initially localized with a phase-dithered MR-tracking sequence to locate microcoils embedded in the transducer. MR-ARFI spots were visualized, observing the change of focal displacement and ease of steering. Finally, MR-ARFI was implemented as the principle liver HIFU calibration system, and MR-ARFI measurements of the focal location relative to the thermal ablation location in breath-hold and breathing experiments were performed. Results: Measuring focal displacement with MR-ARFI was achieved in the phantom and in vivo liver. In one in vivo experiment, where MR-ARFI images were acquired repeatedly at the same location with different powers, the displacement had a linear relationship with power [y?=?0.04x?+?0.83 ?m (R2?=?0.96)]. In another experiment, the displacement images depicted the electronic steering of the focus inside the liver. With the new calibration system, the target focal location before thermal ablation was successfully verified. The entire calibration protocol delivered 20.2 J of energy to the animal (compared to greater than 800 J for a test thermal ablation). ARFI displacement maps were compared with thermal ablations during seven breath-hold ablations. The error was 0.83??0.38 mm in the S?I direction and 0.99??0.45 mm in the L?R direction. For six spots in breathing ablations, the mean error in the nonrespiration direction was 1.02??0.89 mm. Conclusions: MR-ARFI has the potential to improve free-breathing plan execution accuracy compared to current calibration and acoustic beam adjustment practices. Gating the acquisition allows for visualization of the focal spot over the course of respiratory motion, while also being insensitive to motion effects that can complicate a thermal test spot. That MR-ARFI measures a mechanical property at the focus also makes it insensitive to high perfusion, of particular importance to highly perfused organs such as the liver. PMID:21978053

  8. KEYCORP LIMITED Keycorp MULTOS I4F 80K with

    E-print Network

    KEYCORP KEYCORP LIMITED Keycorp MULTOS I4F 80K with MULTOS PIV Card Application FIPS 140-2 Level 2 Security Policy Keycorp MULTOS I4F 80K with MULTOS PIV Card Application FIPS 140-2 Level 2 Security Policy including this Copyright notice. Author: Keycorp Ltd. Document Number: SIM-SP-0304 Date: September 2008

  9. 77 FR 42802 - Section 4(f) Policy Paper

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-20

    ...private historic sites for Federal highway...Section 4(f) Policy Paper replaces the previous...The final Policy Paper includes a link to...area of DOI's Web site in lieu of including...Section 4(f) Policy Papers, the circumstances...f) to a historic site that is not on...

  10. Acoustic imaging, visualization, and quantification of buoyant hydrothermal plumes in the Ocean

    NASA Astrophysics Data System (ADS)

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

    We develop and apply visualization and quantification methods to reconstruct hydrothermal plumes in 3D from acoustic images and to make the first direct measurements from the reconstructions of scalar properties that describe the behavior of two buoyant plumes discharging from adjacent black smoker chimneys. The actual behavior is then compared to that predicted by a classic simple buoyant plume model. The images are reconstructed as isointensity surfaces of backscatter from particulate matter suspended in the plumes. The measurements pertinent to the role of the plumes as agents of dispersal of heat and mass into the ocean include change with height of diameter, particle distribution, dilution, centerline attitude, surface protrusions, and connectivity. The protrusions are the surface expression of eddies and appear to follow a bifurcating helical flow pattern that resemble simulation of the naturally forced flow of coherent vortex rings as the eddies rise with the buoyant plume. These direct measurements and the derived entrainment coefficient are generally consistent with behavior predicted by the simple buoyant plume model and support engulfment by vortex shedding as a primary mechanism for entrainment of surrounding seawater. Deviations from predicted buoyant plume behavior are diagnostic of particle dynamics.

  11. 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

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

    PubMed Central

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

    2014-01-01

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

  13. The coordination chemistry and magnetism of some 3d4f and 4f amino-polyalcohol compounds

    PubMed Central

    Sharples, Joseph W.; Collison, David

    2014-01-01

    Triethanolamine, teaH3, and diethanolamine, RdeaH2, 3d4f and 4f compounds demonstrate an enormous variety in their structure and bonding. This review examines the synthetic strategies to these molecules and their magnetic properties, whilst trying to assess these ligands suitability towards new SMMs and magnetic refrigerants. PMID:25009361

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

    SciTech Connect

    Connolly, G. D.; Rokhlin, S. I.

    2011-06-23

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

  15. Non-intrusive, high-resolution, real-time, two-dimensional imaging of multiphase materials using acoustic array sensors

    NASA Astrophysics Data System (ADS)

    Casside, M.; Shaw, J. M.

    2015-04-01

    Two parallel multi-element ultrasonic acoustic arrays combined with sets of focal laws for acoustic signal generation and a classical tomographic inversion algorithm are used to generate real-time two-dimensional micro seismic acoustic images of multiphase materials. Proof of concept and calibration measurements were performed for single phase and two phase liquids, uniform polyvinyl chloride (PVC) plates, and aluminum cylinders imbedded in PVC plates. Measurement artefacts, arising from the limited range of viewing angles, and the compromise between data acquisition rate and image quality are discussed. The angle range of scanning and the image resolution were varied, and the effects on the quality of the reproduction of the speed of sound profiles of model solids and liquids with known geometries and compositions were analysed in detail. The best image quality results were obtained for a scanning angle range of [-35, 35] at a step size of 2.5 post processed to generate images on a 40 ?m square grid. The data acquisition time for high quality images with a 30 mm 40 mm view field is 10 min. Representation of two-phase solids with large differences in speed of sound between phases and where one phase is dispersed in the form of macroscopic objects (greater than 1 mm in diameter) proved to be the most difficult to image accurately. Liquid-liquid and liquid-vapor phase boundaries, in micro porous solids by contrast, were more readily defined. Displacement of air by water and water by heptane in natural porous limestone provides illustrative kinetic examples. Measurement results with these realistic cases demonstrate the feasibility of the technique to monitor in real time and on the micrometer length scale local composition and flow of organic liquids in inorganic porous media, one of many envisioned engineering applications. Improvement of data acquisition rate is an area for future collaborative study.

  16. Non-intrusive, high-resolution, real-time, two-dimensional imaging of multiphase materials using acoustic array sensors

    SciTech Connect

    Casside, M.; Shaw, J. M.

    2015-04-15

    Two parallel multi-element ultrasonic acoustic arrays combined with sets of focal laws for acoustic signal generation and a classical tomographic inversion algorithm are used to generate real-time two-dimensional micro seismic acoustic images of multiphase materials. Proof of concept and calibration measurements were performed for single phase and two phase liquids, uniform polyvinyl chloride (PVC) plates, and aluminum cylinders imbedded in PVC plates. Measurement artefacts, arising from the limited range of viewing angles, and the compromise between data acquisition rate and image quality are discussed. The angle range of scanning and the image resolution were varied, and the effects on the quality of the reproduction of the speed of sound profiles of model solids and liquids with known geometries and compositions were analysed in detail. The best image quality results were obtained for a scanning angle range of [?35, 35] at a step size of 2.5 post processed to generate images on a 40 ?m square grid. The data acquisition time for high quality images with a 30 mm 40 mm view field is 10 min. Representation of two-phase solids with large differences in speed of sound between phases and where one phase is dispersed in the form of macroscopic objects (greater than 1 mm in diameter) proved to be the most difficult to image accurately. Liquid-liquid and liquid-vapor phase boundaries, in micro porous solids by contrast, were more readily defined. Displacement of air by water and water by heptane in natural porous limestone provides illustrative kinetic examples. Measurement results with these realistic cases demonstrate the feasibility of the technique to monitor in real time and on the micrometer length scale local composition and flow of organic liquids in inorganic porous media, one of many envisioned engineering applications. Improvement of data acquisition rate is an area for future collaborative study.

  17. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL, VOL. 38.NO. 2 , MARCH 1991 141 Image Processing for a Scanning Acoustic

    E-print Network

    Khuri-Yakub, Butrus T. "Pierre"

    of surfacefeaturesfromanimagetoobtain enhanced subsurface defect detection.A numerically defocused image 141 Image Processing for a Scanning Acoustic Microscope That Measures Amplitude and Phase Paul A. Reinholdtsen and Butrus T. Khuri-Yakub, Senior Member, IEEE Abstract-Several image processing techniques

  18. 4f electron delocalization and volume collapse in praseodymium metal

    SciTech Connect

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

    2012-04-17

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

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

    PubMed

    Simmons, James A

    2012-04-01

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

  20. Apparatus for real-time acoustic imaging of Rayleigh-Bnard convection

    SciTech Connect

    Kuehn, Kerry, K.

    2008-10-28

    We have successfully designed, built and tested an experimental apparatus which is capable of providing the first real-time ultrasound images of Rayleigh-B\\'{e}nard convection in optically opaque fluids confined to large aspect ratio experimental cells. The apparatus employs a modified version of a commercially available ultrasound camera to capture images (30 frames per second) of flow patterns in a fluid undergoing Rayleigh Bnard convection. The apparatus was validated by observing convection rolls in 5cSt polydimethylsiloxane (PDMS) polymer fluid. Our first objective, after having built the apparatus, was to use it to study the sequence of transitions from diffusive to time--dependent heat transport in liquid mercury. The aim was to provide important information on pattern formation in the largely unexplored regime of very low Prandtl number fluids. Based on the theoretical stability diagram for liquid mercury, we anticipated that straight rolls should be stable over a range of Rayleigh numbers, between 1708 and approximately 1900. Though some of our power spectral densities were suggestive of the existence of weak convection, we have been unable to unambiguously visualize stable convection rolls above the theoretical onset of convection in liquid mercury. Currently, we are seeking ways to increase the sensitivity of our apparatus, such as (i) improving the acoustic impedance matching between our materials in the ultrasound path and (ii) reducing the noise level in our acoustic images due to turbulence and cavitation in the cooling fluids circulating above and below our experimental cell. If we are able to convincingly improve the sensitivity of our apparatus, and we still do not observe stable convection rolls in liquid mercury, then it may be the case that the theoretical stability diagram requires revision. In that case, either (i) straight rolls are not stable in a large aspect ratio cell at the Prandtl numbers associated with liquid mercury, or (ii) they are stable, but not in the region of the stability diagram which has been studied by this experimenter. Our second objective was to use the apparatus to study other optically opaque fluids. To this end, we have obtained the first ultrasound images of Rayleigh-Bnard convection in a ferrofluid (EFH1). This project has provided a vehicle for the scientific training of five undergraduate research assistants during the past four years. It allowed students at Wisconsin Lutheran College, a small undergraduate liberal arts college in Milwaukee, to become directly involved in a significant scientific project from its inception through publication of scientific results. The funding of this project has also strengthened the research and teaching infrastructure at the Wisconsin Lutheran College in three major ways. The project has funded the PI and his students in the design and construction of a major piece of scientific apparatus which is capable of performing novel studies of Rayleigh-Bnard convection in opaque fluids. With the acquisition of this apparatus, we are able to embark on a broad research program to study problems in pattern formation in alloys, ferro-fluids, opaque gels, and liquid metals under thermal or magnetic stresses. This project has allowed the PI to purchase auxiliary equipment necessary for establishing a fluid dynamics research laboratory at the College. And this project has served as an impetus for the College to invest in a new machine shop in the basement of the Science Building at the College in order to support this, and other, scientific projects at the College. The PI has presented work funded by this grant at physics and engineering colloquia at a nearby university and at the keynote presentation at an undergraduate research symposium at Wisconsin Lutheran College. Also, the work was featured in local magazine and newspaper articles, and is described on the PI's research webpage. Such scientific outreach serves to advance the cause of science by making it interesting and accessible to a wider audience, and to bring attention to the wor

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

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...programmatic Section 4(f) evaluations will be coordinated with the Department of Interior, Department of Agriculture, and Department of Housing and Urban Development, and published in the Federal Register for comment prior to being finalized....

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

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...programmatic Section 4(f) evaluations will be coordinated with the Department of Interior, Department of Agriculture, and Department of Housing and Urban Development, and published in the Federal Register for comment prior to being finalized....

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

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...programmatic Section 4(f) evaluations will be coordinated with the Department of Interior, Department of Agriculture, and Department of Housing and Urban Development, and published in the Federal Register for comment prior to being finalized....

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

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...programmatic Section 4(f) evaluations will be coordinated with the Department of Interior, Department of Agriculture, and Department of Housing and Urban Development, and published in the Federal Register for comment prior to being finalized....

  5. 23 CFR 774.3 - Section 4(f) approvals.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...programmatic Section 4(f) evaluations will be coordinated with the Department of Interior, Department of Agriculture, and Department of Housing and Urban Development, and published in the Federal Register for comment prior to being finalized....

  6. A simulation technique for 3D MR-guided acoustic radiation force imaging

    SciTech Connect

    Payne, Allison; Bever, Josh de; Farrer, Alexis; Coats, Brittany; Parker, Dennis L.; Christensen, Douglas A.

    2015-02-15

    Purpose: In magnetic resonance-guided focused ultrasound (MRgFUS) therapies, the in situ characterization of the focal spot location and quality is critical. MR acoustic radiation force imaging (MR-ARFI) is a technique that measures the tissue displacement caused by the radiation force exerted by the ultrasound beam. This work presents a new technique to model the displacements caused by the radiation force of an ultrasound beam in a homogeneous tissue model. Methods: When a steady-state point-source force acts internally in an infinite homogeneous medium, the displacement of the material in all directions is given by the Somigliana elastostatic tensor. The radiation force field, which is caused by absorption and reflection of the incident ultrasound intensity pattern, will be spatially distributed, and the tensor formulation takes the form of a convolution of a 3D Greens function with the force field. The dynamic accumulation of MR phase during the ultrasound pulse can be theoretically accounted for through a time-of-arrival weighting of the Greens function. This theoretical model was evaluated experimentally in gelatin phantoms of varied stiffness (125-, 175-, and 250-bloom). The acoustic and mechanical properties of the phantoms used as parameters of the model were measured using independent techniques. Displacements at focal depths of 30- and 45-mm in the phantoms were measured by a 3D spin echo MR-ARFI segmented-EPI sequence. Results: The simulated displacements agreed with the MR-ARFI measured displacements for all bloom values and focal depths with a normalized RMS difference of 0.055 (range 0.0280.12). The displacement magnitude decreased and the displacement pattern broadened with increased bloom value for both focal depths, as predicted by the theory. Conclusions: A new technique that models the displacements caused by the radiation force of an ultrasound beam in a homogeneous tissue model theory has been rigorously validated through comparison with experimentally obtained 3D displacement data in homogeneous gelatin phantoms using a 3D MR-ARFI sequence. The agreement of the experimentally measured and simulated results demonstrates the potential to use MR-ARFI displacement data in MRgFUS therapies.

  7. Near-field radio-frequency thermo-acoustic imaging based on transmission lines for optimized performance

    NASA Astrophysics Data System (ADS)

    Omar, Murad; Kellnberger, Stephan; Sergiadis, George; Razansky, Daniel; Ntziachristos, Vasilis

    2012-02-01

    Near-field Radio-frequency Thermoacoustic Imaging (NRTI) is an imaging modality that was recently introduced to generate thermoacoustic signals using ultra-short high energy impulses. Because it allows for a higher energy coupling within an ultra-short time, it can achieve higher resolutions and higher signal to noise ratio, compared to traditional thermoacoustic tomography based on radiating sources at single frequencies. As for traditional thermoacoustic imaging the contrast comes from the conductivity and the dielectric properties of the tissues, while the resolution depends on the measured acoustic waves. Since NRTI depends on the efficient generation of high energy short impulses, the ability to control their time width and pulse shape is of high importance. We present here a methodology for generating such impulses based on transmission lines. The ability of such generators to generate impulses in the range of tens of nanoseconds enables high resolution images in the range of tens of microns to hundreds of microns without compromising the amount of the energy coupled. Finally the pulser is used to generate high resolution images of small absorbing insertions, of phantoms with different conductivities and of ex-vivo mouse images. From the phantoms it is possible to see both the capabilities of the system to accurately image small insertions as well as the high quality images generated from imaging phantoms, from ex-vivo mouse images it is possible to see several anatomical characteristics, such as the mouse boundary, the spine and some other characteristics in the mouse abdomens.

  8. 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.

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

    PubMed Central

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

    2013-01-01

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

  10. Comparison of Acoustic Radiation Force Impulse Imaging Derived Carotid Plaque Stiffness With Spatially Registered MRI Determined Composition.

    PubMed

    Doherty, Joshua R; Dahl, Jeremy J; Kranz, Peter G; El Husseini, Nada; Chang, Hing-Chiu; Chen, Nan-Kuei; Allen, Jason D; Ham, Katherine L; Trahey, Gregg E

    2015-11-01

    Measurements of plaque stiffness may provide important prognostic and diagnostic information to help clinicians distinguish vulnerable plaques containing soft lipid pools from more stable, stiffer plaques. In this preliminary study, we compare in vivo ultrasonic Acoustic Radiation Force Impulse (ARFI) imaging derived measures of carotid plaque stiffness with composition determined by spatially registered Magnetic Resonance Imaging (MRI) in five human subjects with stenosis > 50%. Ultrasound imaging was implemented on a commercial diagnostic scanner with custom pulse sequences to collect spatially registered 2D longitudinal B-mode and ARFI images. A standardized, multi-contrast weighted MRI sequence was used to obtain 3D Time of Flight (TOF), T1 weighted (T1W), T2 weighted (T2W), and Proton Density Weighted (PDW) transverse image stacks of volumetric data. The MRI data was segmented to identify lipid, calcium, and normal loose matrix components using commercially available software. 3D MRI segmented plaque models were rendered and spatially registered with 2D B-mode images to create fused ultrasound and MRI volumetric images for each subject. ARFI imaging displacements in regions of interest (ROIs) derived from MRI segmented contours of varying composition were compared. Regions of calcium and normal loose matrix components identified by MRI presented as homogeneously stiff regions of similarly low (typically ? 1 ?m) displacement in ARFI imaging. MRI identified lipid pools > 2 mm(2), found in three out of five subjects, presented as softer regions of increased displacement that were on average 1.8 times greater than the displacements in adjacent regions of loose matrix components in spatially registered ARFI images. This work provides early evidence supporting the use of ARFI imaging to noninvasively identify lipid regions in carotid artery plaques in vivo that are believed to increase the propensity of a plaque to rupture. Additionally, the results provide early training data for future studies and aid in the interpretation and possible clinical utility of ARFI imaging for identifying the elusive vulnerable plaque. PMID:25974933

  11. Computations of the acoustically induced phase shifts of optical paths in acoustophotonic imaging with photorefractive-based detection.

    PubMed

    Blonigen, Florian J; Nieva, Alex; DiMarzio, Charles A; Manneville, Sbastien; Sui, Lei; Maguluri, Gopi; Murray, Todd W; Roy, Ronald A

    2005-06-20

    Acoustophotonic imaging uses ultrasound-modulated scattered light to improve the quality of optical imaging in diffusive media. Experiments that use photorefractive-crystal-based detection have shown that there is a large dc shift in the acoustically modulated or ac optical signal, which could be utilized to further improve optical imaging resolution. We report that photon paths in a diffusive medium were generated by a Monte Carlo simulation, and the optical phase shifts of the various photons induced by the presence of a realistic focused ultrasound beam were calculated. Quantities that characterize the ac and dc signal components were evaluated by use of the calculated phase shifts. It was confirmed that the dc component dominates owing to coherent summation of the contributions from all the photons. PMID:15989048

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

    SciTech Connect

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

    2005-05-15

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

  13. Imaging and characterizing shear wave and shear modulus under orthogonal acoustic radiation force excitation using OCT Doppler variance method.

    PubMed

    Zhu, Jiang; Qu, Yueqiao; Ma, Teng; Li, Rui; Du, Yongzhao; Huang, Shenghai; Shung, K Kirk; Zhou, Qifa; Chen, Zhongping

    2015-05-01

    We report on a novel acoustic radiation force orthogonal excitation optical coherence elastography (ARFOE-OCE) technique for imaging shear wave and quantifying shear modulus under orthogonal acoustic radiation force (ARF) excitation using the optical coherence tomography (OCT) Doppler variance method. The ARF perpendicular to the OCT beam is produced by a remote ultrasonic transducer. A shear wave induced by ARF excitation propagates parallel to the OCT beam. The OCT Doppler variance method, which is sensitive to the transverse vibration, is used to measure the ARF-induced vibration. For analysis of the shear modulus, the Doppler variance method is utilized to visualize shear wave propagation instead of Doppler OCT method, and the propagation velocity of the shear wave is measured at different depths of one location with the M scan. In order to quantify shear modulus beyond the OCT imaging depth, we move ARF to a deeper layer at a known step and measure the time delay of the shear wave propagating to the same OCT imaging depth. We also quantitatively map the shear modulus of a cross-section in a tissue-equivalent phantom after employing the B scan. PMID:25927794

  14. Redetermination of durangite, NaAl(AsO4)F

    PubMed Central

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

    2012-01-01

    The crystal structure of durangite, ideally NaAl(AsO4)F (chemical name sodium aluminium arsenate fluoride), has been determined previously [Kokkoros (1938). Z. Kristallogr. 99, 3849] using Weissenberg film data without reporting displacement parameters of atoms or a reliability factor. This study reports the redetermination of the structure of durangite using single-crystal X-ray diffraction data from a natural sample with composition (Na0.95Li0.05)(Al0.91Fe3+ 0.07Mn3+ 0.02)(AsO4)(F0.73(OH)0.27) from the type locality, the Barranca mine, Coneto de Comonfort, Durango, Mexico. Durangite is isostructural with minerals of the titanite group in the space group C2/c. Its structure is characterized by kinked chains of corner-sharing AlO4F2 octahedra parallel to the c axis. These chains are cross-linked by isolated AsO4 tetrahedra, forming a three-dimensional framework. The Na+ cation (site symmetry 2) occupies the interstitial sites and is coordinated by one F? and six O2? anions. The AlO4F2 octahedron has symmetry -1; it is flattened, with the AlF bond length [1.8457?(4)?] shorter than the AlO bond lengths [1.8913?(8) and 1.9002?(9)?]. Examination of the Raman spectra for arsenate minerals in the titanite group reveals that the position of the band originating from the AsO symmetric stretching vibrations shifts to lower wavenumbers from durangite, maxwellite [ideally NaFe(AsO4)F], to tilasite [CaMg(AsO4)F]. PMID:23284315

  15. Quantitative assessment of acoustic intensity in the focused ultrasound field using hydrophone and infrared imaging.

    PubMed

    Yu, Ying; Shen, Guofeng; Zhou, Yufeng; Bai, Jingfeng; Chen, Yazhu

    2013-11-01

    With the popularity of ultrasound therapy in clinics, characterization of the acoustic field is important not only to the tolerability and efficiency of ablation, but also for treatment planning. A quantitative method was introduced to assess the intensity distribution of a focused ultrasound beam using a hydrophone and an infrared camera with no prior knowledge of the acoustic and thermal parameters of the absorber or the configuration of the array elements. This method was evaluated in both theoretical simulations and experimental measurements. A three-layer model was developed to calculate the acoustic field in the absorber, the absorbed acoustic energy during the sonication and the consequent temperature elevation. Experiments were carried out to measure the acoustic pressure with the hydrophone and the temperature elevation with the infrared camera. The percentage differences between the derived results and the simulation are <4.1% for on-axis intensity and <21.1% for -6-dB beam width at heating times up to 360ms in the focal region of three phased-array ultrasound transducers using two different absorbers. The proposed method is an easy, quick and reliable approach to calibrating focused ultrasound transducers with satisfactory accuracy. PMID:23972377

  16. 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.

  17. 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, Andr; 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.

  18. 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.

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

    SciTech Connect

    Hampton, M A.; Karl, H; Murray, Christopher J. )

    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.

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

    PubMed Central

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

    2014-01-01

    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

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

    NASA Astrophysics Data System (ADS)

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

    2009-07-01

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

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

    E-print Network

    Arnold, Craig B.

    (TAG) index of refraction lens as a fast varifocal element. The optical power of the TAG lens varies crystals for focusing a beam. Recently, TAG lenses emerged as a new generation of high-speed tunable correspond to the static refractive in- dex and to the speed of sound in the acoustic me- dium, respectively

  3. 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 bloods 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

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

    E-print Network

    Grasland-Mongrain, Pol

    2014-01-01

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

  5. 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; ODonnell, 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 catheters 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

  6. 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

  7. B-Mode and Acoustic Radiation Force Impulse (ARFI) Imaging of Prostate Zonal Anatomy: Comparison with 3T T2-Weighted MR Imaging

    PubMed Central

    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 (R2 = 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 (R2 = 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

  8. Acoustic neuroma

    MedlinePLUS

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

  9. Comparison of analytical and numerical approaches for CT-based aberration correction in transcranial passive acoustic imaging.

    PubMed

    Jones, Ryan M; Hynynen, Kullervo

    2016-01-01

    Computed tomography (CT)-based aberration corrections are employed in transcranial ultrasound both for therapy and imaging. In this study, analytical and numerical approaches for calculating aberration corrections based on CT data were compared, with a particular focus on their application to transcranial passive imaging. Two models were investigated: a three-dimensional full-wave numerical model (Connor and Hynynen 2004 IEEE Trans. Biomed. Eng. 51 1693-706) based on the Westervelt equation, and an analytical method (Clement and Hynynen 2002 Ultrasound Med. Biol. 28 617-24) similar to that currently employed by commercial brain therapy systems. Trans-skull time delay corrections calculated from each model were applied to data acquired by a sparse hemispherical (30?cm diameter) receiver array (128 piezoceramic discs: 2.5?mm diameter, 612?kHz center frequency) passively listening through ex vivo human skullcaps (n??=??4) to emissions from a narrow-band, fixed source emitter (1?mm diameter, 516?kHz center frequency). Measurements were taken at various locations within the cranial cavity by moving the source around the field using a three-axis positioning system. Images generated through passive beamforming using CT-based skull corrections were compared with those obtained through an invasive source-based approach, as well as images formed without skull corrections, using the main lobe volume, positional shift, peak sidelobe ratio, and image signal-to-noise ratio as metrics for image quality. For each CT-based model, corrections achieved by allowing for heterogeneous skull acoustical parameters in simulation outperformed the corresponding case where homogeneous parameters were assumed. Of the CT-based methods investigated, the full-wave model provided the best imaging results at the cost of computational complexity. These results highlight the importance of accurately modeling trans-skull propagation when calculating CT-based aberration corrections. Although presented in an imaging context, our results may also be applicable to the problem of transmit focusing through the skull. PMID:26605827

  10. Comparison of analytical and numerical approaches for CT-based aberration correction in transcranial passive acoustic imaging

    NASA Astrophysics Data System (ADS)

    Jones, Ryan M.; Hynynen, Kullervo

    2016-01-01

    Computed tomography (CT)-based aberration corrections are employed in transcranial ultrasound both for therapy and imaging. In this study, analytical and numerical approaches for calculating aberration corrections based on CT data were compared, with a particular focus on their application to transcranial passive imaging. Two models were investigated: a three-dimensional full-wave numerical model (Connor and Hynynen 2004 IEEE Trans. Biomed. Eng. 51 1693706) based on the Westervelt equation, and an analytical method (Clement and Hynynen 2002 Ultrasound Med. Biol. 28 61724) similar to that currently employed by commercial brain therapy systems. Trans-skull time delay corrections calculated from each model were applied to data acquired by a sparse hemispherical (30?cm diameter) receiver array (128 piezoceramic discs: 2.5?mm diameter, 612?kHz center frequency) passively listening through ex vivo human skullcaps (n??=??4) to emissions from a narrow-band, fixed source emitter (1?mm diameter, 516?kHz center frequency). Measurements were taken at various locations within the cranial cavity by moving the source around the field using a three-axis positioning system. Images generated through passive beamforming using CT-based skull corrections were compared with those obtained through an invasive source-based approach, as well as images formed without skull corrections, using the main lobe volume, positional shift, peak sidelobe ratio, and image signal-to-noise ratio as metrics for image quality. For each CT-based model, corrections achieved by allowing for heterogeneous skull acoustical parameters in simulation outperformed the corresponding case where homogeneous parameters were assumed. Of the CT-based methods investigated, the full-wave model provided the best imaging results at the cost of computational complexity. These results highlight the importance of accurately modeling trans-skull propagation when calculating CT-based aberration corrections. Although presented in an imaging context, our results may also be applicable to the problem of transmit focusing through the skull.

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

    NASA Astrophysics Data System (ADS)

    Prez, Nemesio M.; Somoza, Luis; Hernndez, Pedro A.; de Vallejo, Luis Gonzlez; Len, Ricardo; Sagiya, Takeshi; Biain, Ander; Gonzlez, Francisco J.; Medialdea, Teresa; Barrancos, Jos; Ibez, Jess; Sumino, Hirochika; Nogami, Kenji; Romero, Carmen

    2014-12-01

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

  12. 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.

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

    PubMed

    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

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

    PubMed

    Zhong, Siyang; Wei, Qingkai; Huang, Xun

    2013-11-01

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

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

    SciTech Connect

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

    2008-07-29

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

  16. 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.

    2002-04-30

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

  17. 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. PMID:26161345

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

    NASA Astrophysics Data System (ADS)

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

    2013-01-01

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

  19. Etching of porous and solid SiO2 in Ar/c-C4F8, O2/c-C4F8 and Ar/O2/c-C4F8 plasmas

    E-print Network

    Kushner, Mark

    , Illinois 61801 Mark J. Kushnerb) Department of Electrical and Computer Engineering, University of Illinois mechanism was validated by comparison to experiments for blanket etching of solid and porous SiO2 in Ar/c-C4F8 and O2/c-C4F8 plasmas using inductively coupled plasma reactors. We found that the blanket etch

  20. EXPRESSION OF CYP4F2 IN HUMAN LIVER AND KIDNEY: ASSESSMENT USING TARGETED PEPTIDE ANTIBODIES

    PubMed Central

    Hirani, Vandana; Yarovoy, Anton; Kozeska, Anita; Magnusson, Ronald P.; Lasker, Jerome M.

    2008-01-01

    P450 enzymes comprising the human CYP4F gene subfamily are catalysts of eicosanoid (e.g., 20-HETE and leukotriene B4) formation and degradation, although the role that individual CYP4F proteins play in these metabolic processes is not well defined. Thus, we developed antibodies to assess the tissue-specific expression and function of CYP4F2, one of four CYP4F P450s found in human liver and kidney. Peptide antibodies elicited in rabbits to CYP4F2 amino acid residues 6174 (WGHQGMVNPTEEG) and 6577 (GMVNPTEEGMRVL) recognized on immunoblots only CYP4F2 and not CYP4F3b, CYP4F11 or CYP4F12. Immunoquantitation with anti-CYP4F2 peptide IgG showed highly-variable CYP4F2 expression in liver (16.4 18.6 pmol/mg microsomal protein; n = 29) and kidney cortex (3.9 3.8 pmol/mg; n = 10), with two subjects lacking the hepatic or renal enzyme entirely. CYP4F2 content in liver microsomes was significantly correlated (r ? 0.63; p < 0.05) with leukotriene B4 and arachidonate ?-hydroxylase activities, which are both CYP4F2-catalyzed. Our study provides the first example of a peptide antibody that recognizes a single CYP4F P450 expressed in human liver and kidney, namely CYP4F2. Immunoquantitation and correlation analyses performed with this antibody suggest that CYP4F2 functions as a predominant LTB4 and arachidonate ?-hydroxylase in human liver. PMID:18662666

  1. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

  3. Neutralization epitopes on rotavirus SA11 4fM outer capsid proteins.

    PubMed Central

    Gorziglia, M; Larralde, G; Ward, R L

    1990-01-01

    The VP7 and VP4 genes of seven antigenic mutants of simian rotavirus SA11 4fM (serotype 3) selected after 39 passages in the presence of SA11 4fM hyperimmune antiserum, were sequenced. Nucleotide sequence analysis indicated the following. (i) Twice as many amino acid substitutions occurred in the VP7 protein than in VP4, which has a molecular weight twice that of VP7. (ii) Most amino acid changes that occurred clustered in six variable regions of VP7 and in two variable regions of VP4; these variable regions may represent immunodominant epitopes. (iii) Most amino acid substitutions that occurred in VP7 and VP4 of these mutants were also observed in antigenic mutants selected with neutralizing monoclonal antibodies (NMAbs); however, some amino acid substitutions occurred that were not selected for NMAbs. (iv) On VP7, some of the neutralization epitopes appeared to be interrelated because amino acid substitution in one site affected binding of specific NMAbs to other sites, while other neutralization epitopes on VP7 appeared to be independent, in that amino acid substitution in one site did not affect the binding of NMAbs to another distant site. Images PMID:1696640

  4. 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

  5. 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, Frdric

    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.

  6. Measuring Soft Tissue Elasticity by Monitoring Surface Acoustic Waves Using Image Plane Digital Holography

    E-print Network

    Oldenburg, Amy

    tissues. In this paper, we report our first study to measure elastic properties of soft tissues by mapping techniques, i.e., techniques that image tissue elastic properties. Ultrasound is a popular tool to obtain the SAWs as measured by holographic technology and the elastic properties of tissues. These relationships

  7. 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.

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

    PubMed

    Berry, Gearid 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

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

    PubMed Central

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

    2014-01-01

    Background Acoustic radiation force impulse (ARFI) elastography is a reliable diagnostic device for quantitative non-invasive assessment of liver fibrosis in patients with chronic liver disease. The aim of our prospective study was to evaluate the impact of ARFI in patients after orthotopic liver transplantation (OLT). Therefore, we compared ARFI shear wave velocities with clinical features, non-invasive markers, and the histology of patients following OLT. Material/Methods Post-transplant patients underwent a clinical examination and blood samples were taken. B-mode and Doppler ultrasound (US) of the portal vein and the hepatic artery were performed. Subsequently, a minimum of 10 valid ARFI values were measured in the left and right liver lobe. Liver biopsy was performed if indicated. Results Between May 2012 and May 2014, 58 Patients after OLT were included in the prospective study. Laboratory markers and aspartate aminotransferase-to-platelet ratio index (APRI) correlated with ARFI values (r=0.44, p<0.001). The histological (n=22) fibrosis score (Ludwig) was significantly correlated with the ARFI of the biopsy site (r=0.55, p=0.008). The mean shear-wave velocities were significantly increased in advanced fibrosis (F?2 1.570.57 m/s; F?3 2.850.66 m/s; p<0.001), obstructive cholestasis and active viral hepatitis. The area under the receiver operating characteristic (AUROC) curves for the accuracy of ARFI were 74% (F?1), 73% (F?2), 93% (F?3), and 80% (=F4). Conclusions ARFI elastography correlates well with laboratory values and with noninvasive and invasive markers of fibrosis in patients after OLT. In this regard, elevated ARFI-velocities should be interpreted with caution in the context of obstructive cholestasis and active viral disease. PMID:25342166

  10. 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: 1018 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: 0.3900.859, P<0.001) and 0.627 (95% CI: 0.2330.818, P?=?0.004), respectively. Conclusions ARFI may be an effective tool for evaluating renal histological fibrosis in CKD patients. PMID:25546304

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

    NASA Astrophysics Data System (ADS)

    Acconcia, T. V.; Agcs, A. G.; Barile, F.; Barnafldi, G. G.; Bellwied, R.; Bencdi, G.; Bencze, G.; Bernyi, D.; Boldizsr, 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.; Fut, E.; Garcia-Solis, E.; Hamar, G.; Harton, A.; Iannone, G.; Jimenez, R. T.; Kim, D. W.; Kim, J. S.; Knospe, A.; Kovcs, L.; Lvai, P.; Markert, C.; Martinengo, P.; Molnr, L.; Nappi, E.; Olh, L.; Pai?, G.; Pastore, C.; Patimo, G.; Patino, M. E.; Peskov, V.; Pinsky, L.; Piuz, F.; Pochybov, 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.

  12. 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.

  13. ACOUSTIC-PHONETIC UNIT SIMILARITIES FOR CONTEXT DEPENDENT ACOUSTIC MODEL PORTABILITY

    E-print Network

    Schultz, Tanja

    ACOUSTIC-PHONETIC UNIT SIMILARITIES FOR CONTEXT DEPENDENT ACOUSTIC MODEL PORTABILITY Viet Bac Le-bac.le@imag.fr ABSTRACT This paper addresses particularly the use of acoustic-phonetic unit similarities for portability of context dependent acoustic models to new languages. Since the IPA-based method is limited to a source

  14. Very high-resolution seismo-acoustic imaging of seagrass meadows (Mediterranean Sea): Implications for carbon sink estimates

    NASA Astrophysics Data System (ADS)

    Lo Iacono, Claudio; Mateo, Miguel Angel; Grcia, Eullia; Guasch, Lluis; Carbonell, Ramon; Serrano, Laura; Serrano, Oscar; Daobeitia, Juanjo

    2008-09-01

    Posidonia oceanica is a widespread coastal Mediterranean seagrass which accumulates in its subsurface large quantities of organic material derived from its roots, rhizomes and leaf sheaths embedded in sandy sediments. These organic deposits may be up to several meters thick as they accumulate over thousands of years forming the matte, whose high content in organic carbon plays a major role in the global ocean carbon cycle. In this study, very high-resolution seismo-acoustic methods were applied to image the subsurface features of a P. oceanica seagrass meadow at Portlligat (Cadaqus, Girona, Spain), in the NW-Mediterranean Sea. Our findings yield fresh insights into the settling of the P. oceanica meadow in the study area, and define with unprecedented detail the potential volume occupied by the matte. A strong reflector, located from 4.3 to 11.7 m depth, was recognized in several seismo-acoustic profiles as the substratum on which P. oceanica first settled in the study area. A 3D bathymetric model of this substratum allowed us to reconstruct the Portlligat palaeo-environment prior to the settling of P. oceanica, which corresponded to a shallow coastal setting protected from the open sea. A core drilled in the meadow at Portlligat revealed the presence of a 6 m thick dense matte composed of medium to coarse sandy sediments mixed with plant debris and bioclasts. Radiocarbon datings revealed a constant accretion rate of the matte of about 1.1 m/kyr. Gravelly bioclastic deposits observed at the base of the core correspond to the base of the matte and gave a date of 5616 +/- 46 Cal yr BP. For the first time, very high-resolution marine geophysical techniques allowed us to accurately define the volume occupied by P. oceanica matte, which in the study area reaches up to almost 220,000 +/- 17,400 m3. This result is an important step forward in our efforts to estimate the size of the carbon sink represented by P. oceanica meadows along the Mediterranean coasts significantly contributing to the biosphere carbon cycle.

  15. 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

  16. Ocean acoustic reverberation tomography.

    PubMed

    Dunn, Robert A

    2015-12-01

    Seismic wide-angle imaging using ship-towed acoustic sources and networks of ocean bottom seismographs is a common technique for exploring earth structure beneath the oceans. In these studies, the recorded data are dominated by acoustic waves propagating as reverberations in the water column. For surveys with a small receiver spacing (e.g., <10?km), the acoustic wave field densely samples properties of the water column over the width of the receiver array. A method, referred to as ocean acoustic reverberation tomography, is developed that uses the travel times of direct and reflected waves to image ocean acoustic structure. Reverberation tomography offers an alternative approach for determining the structure of the oceans and advancing the understanding of ocean heat content and mixing processes. The technique has the potential for revealing small-scale ocean thermal structure over the entire vertical height of the water column and along long survey profiles or across three-dimensional volumes of the ocean. For realistic experimental geometries and data noise levels, the method can produce images of ocean sound speed on a smaller scale than traditional acoustic tomography. PMID:26723303

  17. A method of construction of information images of the acoustic signals of the human bronchopulmonary system

    NASA Astrophysics Data System (ADS)

    Bureev, A. Sh.; Zhdanov, D. S.; Zemlyakov, I. Yu.; Kiseleva, E. Yu.; Khokhlova, L. A.

    2015-11-01

    The present study focuses on the development of a method of identification of respiratory sounds and noises of a human naturally and in various pathological conditions. The existing approaches based on a simple method of frequency and time signal analysis, have insufficient specificity, efficiency and unambiguous interpretation of the results of a clinical study. An algorithm for a phase selection of respiratory cycles and analysis of respiratory sounds resulting from bronchi examination of a patient has been suggested. The algorithm is based on the method of phase timing analysis of bronchi phonograms. The results of the phase-frequency algorithm with high resolution reflects a time position of the traceable signals and the individual structure of recorded signals. This allows using the proposed method for the formation of information images (models) of the diagnostically significant fragments. A weight function, frequency parameters of which can be selectively modified, is used for this purpose. The vision of the weighting function is specific to each type of respiratory noise, traditionally referred to quality characteristics (wet or dry noise, crackling, etc.).

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

    SciTech Connect

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

    1999-07-01

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

  19. 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.

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

    NASA Astrophysics Data System (ADS)

    Chu, Zhigang; Yang, Yang

    2014-10-01

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

  1. 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 dBcm?1MHz?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

  2. Acoustic Neuroma

    MedlinePLUS

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

  3. Acoustic emission linear pulse holography

    DOEpatents

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

    1983-10-25

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

  4. Acoustic sniper localization system

    NASA Astrophysics Data System (ADS)

    Prado, Gervasio; Dhaliwal, Hardave; Martel, Philip O.

    1997-02-01

    Technologies for sniper localization have received increased attention in recent months as American forces have been deployed to various trouble spots around the world. Among the technologies considered for this task acoustics is a natural choice for various reasons. The acoustic signatures of gunshots are loud and distinctive, making them easy to detect even in high noise background environments. Acoustics provides a passive sensing technology with excellent range and non line of sight capabilities. Last but not least, an acoustic sniper location system can be built at a low cost with off the shelf components. Despite its many advantages, the performance of acoustic sensors can degrade under adverse propagation conditions. Localization accuracy, although good, is usually not accurate enough to pinpoint a sniper's location in some scenarios (for example which widow in a building or behind which tree in a grove). For these more demanding missions, the acoustic sensor can be used in conjunction with an infra red imaging system that detects the muzzle blast of the gun. The acoustic system can be used to cue the pointing system of the IR camera in the direction of the shot's source.

  5. Broadband Acoustic Hyperbolic Metamaterial.

    PubMed

    Shen, Chen; Xie, Yangbo; Sui, Ni; Wang, Wenqi; Cummer, Steven A; Jing, Yun

    2015-12-18

    In this Letter, we report on the design and experimental characterization of a broadband acoustic hyperbolic metamaterial. The proposed metamaterial consists of multiple arrays of clamped thin plates facing the y direction and is shown to yield opposite signs of effective density in the x and y directions below a certain cutoff frequency, therefore, yielding a hyperbolic dispersion. Partial focusing and subwavelength imaging are experimentally demonstrated at frequencies between 1.0 and 2.5 kHz. The proposed metamaterial could open up new possibilities for acoustic wave manipulation and may find usage in medical imaging and nondestructive testing. PMID:26722924

  6. Evaluating the Acoustic Effect of Over-the-Rotor Foam-Metal Liner Installed on a Low Speed Fan Using Virtual Rotating Microphone Imaging

    NASA Technical Reports Server (NTRS)

    Sutliff, Daniel L.; Dougherty, Robert P.; Walker, Bruce E.

    2010-01-01

    An in-duct beamforming technique for imaging rotating broadband fan sources has been used to evaluate the acoustic characteristics of a Foam-Metal Liner installed over-the-rotor of a low-speed fan. The NASA Glenn Research Center s Advanced Noise Control Fan was used as a test bed. A duct wall-mounted phased array consisting of several rings of microphones was employed. The data are mathematically resampled in the fan rotating reference frame and subsequently used in a conventional beamforming technique. The steering vectors for the beamforming technique are derived from annular duct modes, so that effects of reflections from the duct walls are reduced.

  7. 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.

  8. 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.

  9. Web Ecology: Recycling HTML pages as XML documents using W4F

    E-print Network

    Pennsylvania, University of

    Web Ecology: Recycling HTML pages as XML documents using W4F Arnaud Sahuguet Department of Computer the World-Wide Web Wrapper Fac- tory (W4F), a Java toolkit to generate wrappers for Web data sources. Some by underlying databases and this proportion keeps increasing. But Web data sources also consist of stand

  10. Web Ecology: Recycling HTML pages as XML documents using W4F

    E-print Network

    Pennsylvania, University of

    Web Ecology: Recycling HTML pages as XML documents using W4F Arnaud Sahuguet Department of Computer present the WorldWide Web Wrapper Fac tory (W4F), a Java toolkit to generate wrappers for Web data by underlying databases and this proportion keeps increasing. But Web data sources also consist of stand

  11. 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

  12. 28 CFR 55.5 - Coverage under section 4(f)(4).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 28 Judicial Administration 2 2012-07-01 2012-07-01 false Coverage under section 4(f)(4). 55.5 Section 55.5 Judicial Administration DEPARTMENT OF JUSTICE (CONTINUED) IMPLEMENTATION OF THE PROVISIONS OF THE VOTING RIGHTS ACT REGARDING LANGUAGE MINORITY GROUPS Nature of Coverage 55.5 Coverage under section 4(f)(4). (a) Coverage formula. Section...

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

    SciTech Connect

    Tittmann, B. R.; Xi, X.

    2014-09-01

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

  14. Investigation of a self-sustained volume discharge in c-C4F8

    NASA Astrophysics Data System (ADS)

    Belevtsev, A. A.; Firsov, K. N.; Kazantsev, S. Yu; Kononov, I. G.; Podlesnykh, S. V.

    2015-11-01

    This paper reports the first experimental study of a self-sustained volume discharge (SSVD) in c-C4F8. The discharge voltage and current oscillograms are taken over a wide range of gas pressures. For the first time an SSVD in c-C4F8 preheated by CO2-laser radiation has been investigated. Some special features and temperature-dependent characteristics of this discharge are revealed. There is discussion on the peculiarities of an SSVD in a preirradiated c-C4F8. To refine the static limiting field in c-C4F8 the static dielectric strength of c-C4F8 is measured on changing the gas pressure by nearly two orders of magnitude.

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

    PubMed Central

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

    2014-01-01

    Cytochrome P450 (CYP) 4A and 4F enzymes metabolize arachidonic acid to 20-hydroxyeicosatetraenoic acid (20-HETE). Although CYP4A-derived 20-HETE is known to have prohypertensive and proangiogenic properties, the effects of CYP4F-derived metabolites are not well characterized. To investigate the role of CYP4F2 in vascular disease, we generated mice with endothelial expression of human CYP4F2 (Tie2-CYP4F2-Tr). LC/MS/MS analysis revealed 2-foldincreases in 20-HETE levels in tissues and endothelial cells (ECs), relative to wild-type (WT) controls. Tie2-CYP4F2-Tr ECs demonstrated increases in growth (267.133.4 vs. 205.013% at 48 h) and tube formation (7.71.1 vs. 1.60.5 tubes/field) that were 20-HETE dependent and associated with up-regulation of prooxidant NADPH oxidase and proangiogenic VEGF. Increases in VEGF and NADPH oxidase levels were abrogated by inhibitors of NADPH oxidase and MAPK, respectively, suggesting the possibility of crosstalk between pathways. Interestingly, IL-6 levels in Tie2-CYP4F2-Tr mice (18.62.7 vs. 7.92.7 pg/ml) were up-regulated via NADPH oxidase- and 20-HETE-dependent mechanisms. Although Tie2-CYP4F2-Tr aortas displayed increased vasoconstriction, vasorelaxation and blood pressure were unchanged. Our findings indicate that human CYP4F2 significantly increases 20-HETE production, CYP4F2-derived 20-HETE mediates EC proliferation and angiogenesis via VEGF- and NADPH oxidase-dependent manners, and the Tie2-CYP4F2-Tr mouse is a novel model for examining the pathophysiological effects of CYP4F2-derived 20-HETE in the vasculature.Cheng, J., Edin, M. L., Hoopes, S. L., Li, H., Bradbury, J. A., Graves, J. P., DeGraff, L. M., Lih, F. B., Garcia, V., Shaik, J. S. B., Tomer, K. B., Flake, G. P., Falck, J. R., Lee, C. R., Poloyac, S. M., Schwartzman, M. L., Zeldin, D. C. Vascular characterization of mice with endothelial expression of cytochrome P450 4F2. PMID:24668751

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

    PubMed

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

    2014-07-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

  18. Photo and thermoluminescence of KMgSO4 F: Ce and :Mn phosphors.

    PubMed

    Poddar, Anuradha; Gedam, S C; Dhoble, S J

    2015-06-01

    KMgSO4 F:Ce and KMgSO4 F:Mn phosphors were prepared by a wet chemical method and studied for their photoluminescence (PL) and thermoluminescence (TL) characteristics. PL emission of KMgSO4 F:Ce peaked at around 440?nm for the excitation at 377?nm due to 5d???4f transition, while KMgSO4 F:Mn had a peak at 540?nm for an excitation at 363?nm and 247?nm due to (4) T1g ???(6) A1g transition. The phosphors also showed good thermoluminescence characteristics when they were exposed to ?-rays at a 5?Gy dose at the rate of 0.36 kGyh(-1) . KMgSO4 F:Ce exhibited a single thermoluminescence (TL) peak at around 167?C and KMgSO4 F:Mn also exhibited a single TL peak at around 177?C. Possible trapping parameters such as order of kinetics (b), the geometrical factor (?g ), the frequency factor (s) and the activation energy were also evaluated by Chen's half width method. This article discusses fundamental PL and TL characteristics in inorganic fluoride material activated by Ce(3+) and Mn(2+) ions and prepared by a wet chemical method. PMID:25204539

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

    PubMed

    Nguyen, Su Duy; Javanainen, Matti; Rissanen, Sami; Zhao, Hongxia; Huusko, Jenni; Kivel, Annukka M; Yl-Herttuala, Seppo; Navab, Mohamad; Fogelman, Alan M; Vattulainen, Ilpo; Kovanen, Petri T; rni, 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

  20. 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.

  1. Topological acoustics.

    PubMed

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

    2015-03-20

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

  2. 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

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

    NASA Astrophysics Data System (ADS)

    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.

  4. Radiation-force-based estimation of acoustic attenuation using harmonic motion imaging (HMI) in phantoms and in vitro livers before and after HIFU ablation

    NASA Astrophysics Data System (ADS)

    Chen, Jiangang; Hou, Gary Y.; Marquet, Fabrice; Han, Yang; Camarena, Francisco; Konofagou, Elisa

    2015-10-01

    Acoustic attenuation represents the energy loss of the propagating wave through biological tissues and plays a significant role in both therapeutic and diagnostic ultrasound applications. Estimation of acoustic attenuation remains challenging but critical for tissue characterization. In this study, an attenuation estimation approach was developed using the radiation-force-based method of harmonic motion imaging (HMI). 2D tissue displacement maps were acquired by moving the transducer in a raster-scan format. A linear regression model was applied on the logarithm of the HMI displacements at different depths in order to estimate the acoustic attenuation. Commercially available phantoms with known attenuations (n=5 ) and in vitro canine livers (n=3 ) were tested, as well as HIFU lesions in in vitro canine livers (n=5 ). Results demonstrated that attenuations obtained from the phantoms showed a good correlation ({{R}2}=0.976 ) with the independently obtained values reported by the manufacturer with an estimation error (compared to the values independently measured) varying within the range of 15-35%. The estimated attenuation in the in vitro canine livers was equal to 0.32??????0.03 dB cm-1 MHz-1, which is in good agreement with the existing literature. The attenuation in HIFU lesions was found to be higher (0.58??????0.06 dB cm-1 MHz-1) than that in normal tissues, also in agreement with the results from previous publications. Future potential applications of the proposed method include estimation of attenuation in pathological tissues before and after thermal ablation.

  5. Radiation-force-based estimation of acoustic attenuation using harmonic motion imaging (HMI) in phantoms and in vitro livers before and after HIFU ablation.

    PubMed

    Chen, Jiangang; Hou, Gary Y; Marquet, Fabrice; Han, Yang; Camarena, Francisco; Konofagou, Elisa

    2015-10-01

    Acoustic attenuation represents the energy loss of the propagating wave through biological tissues and plays a significant role in both therapeutic and diagnostic ultrasound applications. Estimation of acoustic attenuation remains challenging but critical for tissue characterization. In this study, an attenuation estimation approach was developed using the radiation-force-based method of harmonic motion imaging (HMI). 2D tissue displacement maps were acquired by moving the transducer in a raster-scan format. A linear regression model was applied on the logarithm of the HMI displacements at different depths in order to estimate the acoustic attenuation. Commercially available phantoms with known attenuations (n = 5) and in vitro canine livers (n = 3) were tested, as well as HIFU lesions in in vitro canine livers (n = 5). Results demonstrated that attenuations obtained from the phantoms showed a good correlation (R = 0.976) with the independently obtained values reported by the manufacturer with an estimation error (compared to the values independently measured) varying within the range of 15-35%. The estimated attenuation in the in vitro canine livers was equal to 0.32??????0.03 dB cm(-1) MHz(-1), which is in good agreement with the existing literature. The attenuation in HIFU lesions was found to be higher (0.58??????0.06 dB cm(-1) MHz(-1)) than that in normal tissues, also in agreement with the results from previous publications. Future potential applications of the proposed method include estimation of attenuation in pathological tissues before and after thermal ablation. PMID:26371501

  6. 38 | Acoustics Today | Winter 2015 Acoustic Cloaking

    E-print Network

    Norris, Andrew

    38 | Acoustics Today | Winter 2015 Acoustic Cloaking It might drive bats batty, but there is no fundamental physical limitation on developing acoustic cloaking devices. Introduction An acoustic cloak the cloak, making the cloak and the object acoustically "invisible." We do not experience acoustic cloaking

  7. 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.

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

    PubMed

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

    2015-01-15

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

  9. CYP4F18-Deficient Neutrophils Exhibit Increased Chemotaxis to Complement Component C5a

    PubMed Central

    Vaivoda, Rachel; Vaine, Christine; Boerstler, Cassandra; Galloway, Kristy; Christmas, Peter

    2015-01-01

    CYP4Fs were first identified as enzymes that catalyze hydroxylation of leukotriene B4 (LTB4). CYP4F18 has an unusual expression in neutrophils and was predicted to play a role in regulating LTB4-dependent inflammation. We compared chemotaxis of wild-type and Cyp4f18 knockout neutrophils using an in vitro assay. There was no significant difference in the chemotactic response to LTB4, but the response to complement component C5a increased 1.92.25-fold in knockout cells compared to wild-type (P < 0.01). This increase was still observed when neutrophils were treated with inhibitors of eicosanoid synthesis. There were no changes in expression of other CYP4 enzymes in knockout neutrophils that might compensate for loss of CYP4F18 or lead to differences in activity. A mouse model of dextran sodium sulfate colitis was used to investigate the consequences of increased C5a-dependent chemotaxis in vivo, but there was no significant difference in weight loss, disease activity, or colonic tissue myeloperoxidase between wild-type and Cyp4f18 knockout mice. This study demonstrates the limitations of inferring CYP4F function based on an ability to use LTB4 as a substrate, points to expanding roles for CYP4F enzymes in immune regulation, and underscores the in vivo challenges of CYP knockout studies. PMID:26613087

  10. 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.

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

    DOEpatents

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

    2013-01-01

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

  12. 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 ...

  13. Microfiber interferometric acoustic transducers.

    PubMed

    Wang, Xiuxin; Jin, Long; Li, Jie; Ran, Yang; Guan, Bai-Ou

    2014-04-01

    Acoustic and ultrasonic transducers are key components in biomedical information technology, which has been applied in medical diagnosis, photoacoustic endoscopy and photoacoustic imaging. In this paper, an acoustic transducer based on Fabry-Perot interferometer (FPI) fabricated in a microscaled optical fiber is demonstrated. The transducer is fabricated by forming two wavelength-matched Bragg gratings into the microfiber by means of side illumination with a 193nm excimer laser. When placing the transducer in water, the applied acoustic signal periodically changes the refractive index (RI) of the surrounding liquid and modulates the transmission of the FPI based on the evanescent-field interaction between the liquid and the transmitting light. As a result, the acoustic signal can be constructed with a tunable laser whose output wavelength is located at the slope of the inteferometric fringes. The transducer presents a sensitivity of 10 times higher than the counterparts fabricated in conventional singlemode fibers and has great potential to achieve higher resolution for photoacoustic imaging due to its reduced diameter. PMID:24718189

  14. Acoustic window

    NASA Astrophysics Data System (ADS)

    Bullat, David M.; Bradshaw, Philip C.; Brown, Jay C.

    1994-01-01

    A cost-effective, producible improved apparatus for and method of fabricating a transducer acoustic window for a marine environment has acceptable acoustic energy transmitting properties and appropriate mechanical properties to withstand the rigors associated with varying velocities of flowing water, fluctuating temperatures, changing ambient pressures, the abuse attendant operations, etc., that are routinely encountered during a prolonged deployment. The acoustic window has a cast CONAP 1556 polyurethane window portion that extends over a hull opening and on a bearing surface rim about the opening. A number of equidistantly, circumferentially spaced stainless steel inserts are molded in the cast polyurethane window portion.

  15. 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.

  16. 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.

  17. Field ionization process of Eu 4f76snp Rydberg states

    NASA Astrophysics Data System (ADS)

    Zhang, Jing; Shen, Li; Dai, Chang-Jian

    2015-11-01

    The field ionization process of the Eu 4f76snp Rydberg states, converging to the first ionization limit, 4f76s 9S4, is systematically investigated. The spectra of the Eu 4f76snp Rydberg states are populated with three-step laser excitation, and detected by electric field ionization (EFI) method. Two different kinds of the EFI pulses are applied after laser excitation to observe the possible impacts on the EFI process. The exact EFI ionization thresholds for the 4f76snp Rydberg states can be determined by observing the corresponding EFI spectra. In particular, some structures above the EFI threshold are found in the EFI spectra, which may be interpreted as the effect from black body radiation (BBR). Finally, the scaling law of the EFI threshold for the Eu 4f76snp Rydberg states with the effective quantum number is built. Project supported by the National Natural Science Foundation of China (Grant Nos. 11004151 and 11174218).

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

    NASA Astrophysics Data System (ADS)

    Shen, Xiaozhi; Li, Jiguang; Jnsson, 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.

  19. Correlation between CYP4F2 gene rs2108622 polymorphism and susceptibility to ischemic stroke

    PubMed Central

    Meng, Chong; Wang, Juan; Ge, Wei-Ning; Tang, Shao-Can; Xu, Guang-Ming

    2015-01-01

    Objective: To conduct a meta-analysis for the correlation between cytochrome P450 4F2 (CYP4F2) rs2108622 (V433M) gene polymorphism and ischemic stroke. Methods: We retrieved the case-control studies on the correlation between CYP4F2 V433M polymorphism and ischemic stroke included in domestic and international databases before January 2015 and selected the best genetic model, using RevMan 5.2 software for meta-analysis. According to the heterogeneity test results of selected literature, the effect model of consolidated data was selected, and the combined OR and 95% CI were calculated. Results: A total of six documents were included. Recessive model (VM + MM vs. VV) was selected as the best genetic model. The combined results showed that: compared with wild-type VV, there are significant association between ischemic stroke and CYP4F2 polymorphism (OR merge = 1.37, 95% CI: 1.21~1.54, P < 0.001). Conclusion: CYP4F2 V433M may be the susceptibility gene for ischemic stroke. PMID:26629123

  20. Room Acoustics

    NASA Astrophysics Data System (ADS)

    Kuttruff, Heinrich; Mommertz, Eckard

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

  1. 2.4 F F F F 3.1 F ( F F F F web)

    E-print Network

    Santipach, - Wiroonsak

    2554 #12;F F 1 1. F 2 2. F F F F 2 2.1 F 2.2 F 2.3 2.4 F F F F 2 3 15 17 3. F 19 3.1 F ( F F F F web) 3.2 F F 3.3 F F 3.4 F F F 3.5 F 3.6 F 3.6.1 F 3.6.2 F ( ) 3.7 online 3.8 ( ) 3.9 website 19 20 21 21 22 25 25 27 29 30 31 4. / F 5. F F 6. 34 35 36 #12;- 1 - F

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

    SciTech Connect

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

    2014-12-28

    Lanthanide tetrahalide molecules LnX{sub 4} (Ln = Ce, Pr, Tb; X = F, Cl, Br, I) have been investigated by density functional theory at the levels of the relativistic Zero Order Regular Approximation and the relativistic energy-consistent pseudopotentials, using frozen small- and medium-cores. The calculated bond lengths and vibrational frequencies are close to the experimental data. Our calculations indicate 4f shell contributions to bonding in LnX{sub 4}, in particular for the early lanthanides, which show significant overlap between the Ln 4f-shell and the halogen np-shells. The 4f shells contribute to Ln-X bonding in LnX{sub 4} about one third more than in LnX{sub 3}.

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

    PubMed Central

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

    2014-01-01

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

  4. Assignment of 4f?5d excitation spectra of Nd in crystals using the simple model

    NASA Astrophysics Data System (ADS)

    Xia, Shangda; Duan, Chang-Kui; Deng, Quan; Ruan, Gang

    2005-09-01

    The measured low-temperature (4f)3?(4f)25d excitation spectra of Nd doped in crystals YPO4, CaF4 and LiYF4 [van Pieterson et al., Phys. Rev. B 65 (2002) 045113] are assigned and analyzed using the simple model proposed by Duan et al. [Phys. Rev. B 66 (2002) 155108] and Ning et al. [J. Alloy. Compd. 366 (2004) 34]. The agreement between theoretical and observed energies and intensities are acceptable, and at the same time the spectra are assigned in more detail.

  5. Auger decay paths of mercury 5 p and 4 f vacancies revealed by multielectron spectroscopy

    NASA Astrophysics Data System (ADS)

    Palaudoux, J.; Huttula, S.-M.; Huttula, M.; Penent, F.; Andric, L.; Lablanquie, P.

    2015-01-01

    Single and double Auger processes following ionization of 4 f and 5 p inner shells have been studied using multielectron coincidence spectroscopy. Coincidence technique enables us to resolve state by state all single and double Auger paths with a resolution better than the lifetime broadening. Drastic step-to-step decay lifetime changes are observed and reported as Coster-Kronig transition takes place either in the first (5 p ) or in the second (4 f ) step of the Auger cascade. Relativistic ab initio theory has been used to predict and interpret the experimental observations.

  6. Temperature dependent magnetic structure of lithium delithiated LixFeSO4F (x = 0, 1) by Mssbauer spectroscopy

    NASA Astrophysics Data System (ADS)

    Lee, In Kyu; Wook Hyun, Sung; Kouh, Taejoon; Shim, In-Bo; Sung Kim, Chul

    2012-04-01

    Recently, lithium iron sulfate compounds have been highly considered for a positive electrode material for lithium ion batteries. In this work, LiFeSO4F and the fully delithiated FeSO4F were prepared by the ionothermal process and chemical oxidation reaction method. The LixFeSO4F (x = 0, 1) samples show the triclinic structure with P-1 space group. In the case of delithiated FeSO4F, changes in lattice parameters were observed due to the disappearance of the Li site while maintaining the triclinic structure. Temperature-dependent magnetic susceptibility curves show the antiferromagnetic (AFM) structure with the ordering temperature of 28 K for LiFeSO4F and 99 K for FeSO4F. Also, temperature-dependent Mssbauer spectra of LiFeSO4F below TN were fitted with two-sets of eight Lorentzian indicating the existence of two different types of Fe2+ ions due to the different hyperfine and electric quadrupole interactions. With the lithium delithiated, the Fe3+ iron ions in FeSO4F exhibit two-sets of six-line patterns due to the electron transfer in FeO4F2 site by lithium delithiation. These suggest that the different AFM ordering in LixFeSO4F can be originated from the Fe2+/Fe3+ magnetic ions with different charge distributions and spin contributions.

  7. 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

  8. First-principles study on site preference and 4f ? 5d transitions of Ce(3+) in Sr3AlO4F.

    PubMed

    Ning, Lixin; Wang, Yongfeng; Wang, Zongcui; Jin, Wei; Huang, Shizhong; Duan, Changkui; Zhang, Yongfan; Chen, Wanping; Liang, Hongbin

    2014-02-13

    The local structures and 4f ? 5d transition energies of Ce(3+) located on the two crystallographic strontium sites of Sr3AlO4F, with charge compensation by means of nearby sodium substitutions for strontium (NaSr') or oxygen substitutions for coordinating fluorine (OF'), have been studied using the density functional theory (DFT) within the supercell model and the wave function-based embedded cluster calculations, respectively. The DFT total energy calculations show that Ce(3+) prefers strongly to occupy the eight-coordinated (Sr2) site over the ten-coordinate (Sr1) site. On the basis of the results from embedded cluster calculations at the CASPT2 level with the spin-orbit effect, the experimentally observed excitation bands are identified in association with the charge-compensated cerium centers. Especially, the two bands observed at ?404 and ?440 nm have been both assigned to the Ce(3+) located at the Sr2 sites but with compensation by one and two nearest-neighbor OF' substitutions, respectively, rather than to the Ce(3+) on the Sr1 and the Sr2 sites, respectively, as proposed earlier. Furthermore, the structural and electronic reasons for the red shift of the lowest 4f ? 5d transition caused by coordinating OF' substitutions are analyzed in terms of the variations in centroid energy and crystal-field splitting of the 5d(1) configuration with the local environment. Finally, the thermal quenching of 5d luminescence at relatively high Ce(3+) concentrations is discussed on the basis of the electronic properties calculated with the hybrid DFT method. PMID:24450534

  9. The Acoustic Oceanographic Buoy A Light Acoustic Data Acquisition System

    E-print Network

    Jesus, Srgio M.

    The Acoustic Oceanographic Buoy A Light Acoustic Data Acquisition System Cristiano Soares Sea Trials Description Conclusion and Acknowledgements Introduction The Acoustic Oceanographic Buoy (AOB) is a light acoustic receiving device that incorporates acoustic and non-acoustic signals received

  10. High-resolution imaging of gigahertz polarization response arising from the interference of reflected surface acoustic waves.

    PubMed

    Yahyaie, I; Buchanan, D A; Bridges, G E; Thomson, D J; Oliver, D R

    2012-06-01

    The surface polarization caused by traveling SAWs at 1.585 GHz has been imaged using a dynamic homodyne electrostatic force microscope technique. Instead of measuring topographic changes caused by the SAW, the reported technique measures polarization in the piezoelectric substrate arising from mechanical stress caused by the SAW. The polarization associated with this stress field modulates the scanning probe cantilever deflection amplitude, which is extracted using a lock-in-based technique. High-resolution imaging is presented with images of the interference arising from a metal reflector on a SAW device. A mathematical model combining SAW generation and force interactions between the probe and the substrate was used to verify the experimental data. In addition to overcoming the challenge associated with detecting and imaging polarization effects at gigahertz frequencies, this imaging technique will greatly assist the development of SAW-based devices that exploit the reflection and interference of SAWs in areas as diverse as microfluidic mixing, cell sorting, and quantum entanglement. PMID:22718871

  11. Bulk plasma fragmentation in a C4F8 inductively coupled plasma: A hybrid modeling study

    NASA Astrophysics Data System (ADS)

    Zhao, Shu-Xia; Zhang, Yu-Ru; Gao, Fei; Wang, You-Nian; Bogaerts, Annemie

    2015-06-01

    A hybrid model is used to investigate the fragmentation of C4F8 inductive discharges. Indeed, the resulting reactive species are crucial for the optimization of the Si-based etching process, since they determine the mechanisms of fluorination, polymerization, and sputtering. In this paper, we present the dissociation degree, the density ratio of F vs. CxFy (i.e., fluorocarbon (fc) neutrals), the neutral vs. positive ion density ratio, details on the neutral and ion components, and fractions of various fc neutrals (or ions) in the total fc neutral (or ion) density in a C4F8 inductively coupled plasma source, as well as the effect of pressure and power on these results. To analyze the fragmentation behavior, the electron density and temperature and electron energy probability function (EEPF) are investigated. Moreover, the main electron-impact generation sources for all considered neutrals and ions are determined from the complicated C4F8 reaction set used in the model. The C4F8 plasma fragmentation is explained, taking into account many factors, such as the EEPF characteristics, the dominance of primary and secondary processes, and the thresholds of dissociation and ionization. The simulation results are compared with experiments from literature, and reasonable agreement is obtained. Some discrepancies are observed, which can probably be attributed to the simplified polymer surface kinetics assumed in the model.

  12. 48 CFR 47.303-4 - F.o.b. origin, freight prepaid.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Administration prescribes commercial zones at Subpart B of 49 CFR part 372); and (2) The cost of transportation... 48 Federal Acquisition Regulations System 1 2011-10-01 2011-10-01 false F.o.b. origin, freight... CONTRACT MANAGEMENT TRANSPORTATION Transportation in Supply Contracts 47.303-4 F.o.b. origin,...

  13. 48 CFR 47.303-4 - F.o.b. origin, freight prepaid.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Administration prescribes commercial zones at Subpart B of 49 CFR part 372); and (2) The cost of transportation... 48 Federal Acquisition Regulations System 1 2010-10-01 2010-10-01 false F.o.b. origin, freight... CONTRACT MANAGEMENT TRANSPORTATION Transportation in Supply Contracts 47.303-4 F.o.b. origin,...

  14. Proposed Plan for the Burma Road Rubble Pit (231-4F)

    SciTech Connect

    Palmer, E.

    1995-11-01

    The purpose of this proposed plan is to describe the preferred alternative for addressing the Burma Road Rubble Pit (BRRP) source unit soils (231-4F) located at the SRS in Aiken, South Carolina and to provide an opportunity for public input into the remedial action selection process.

  15. 28 CFR 55.8 - Relationship between section 4(f)(4) and section 203(c).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 28 Judicial Administration 2 2010-07-01 2010-07-01 false Relationship between section 4(f)(4) and section 203(c). 55.8 Section 55.8 Judicial Administration DEPARTMENT OF JUSTICE (CONTINUED) IMPLEMENTATION OF THE PROVISIONS OF THE VOTING RIGHTS ACT REGARDING LANGUAGE MINORITY GROUPS Nature of Coverage ...

  16. WysiWyg Web Wrapper Factory (W4F) Arnaud Sahuguet

    E-print Network

    Pennsylvania, University of

    WysiWyg Web Wrapper Factory (W4F) Arnaud Sahuguet Department of Computer and Information Science it is based on open standards, it has entry costs for publishers and offers free navigation tools for end is automation of the entire process, Web awareness among Web services (services taking advantage of one another

  17. WysiWyg Web Wrapper Factory (W4F) Arnaud Sahuguet

    E-print Network

    Pennsylvania, University of

    WysiWyg Web Wrapper Factory (W4F) Arnaud Sahuguet Department of Computer and Information Science it is based on open standards, it has entry costs for publishers and o ers free navigation tools for end is automation of the entire process, Web- awareness among Web services (services taking advantage of one another

  18. Multi-cations doped LiVPO4F cathode for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Zhang, Rui; Sun, Xiaofei; Xu, Youlong; Teng, Feng; Sun, Gongyu; Chen, Yanjun; Chen, Guogang

    2015-05-01

    The multi-cations doped LiVPO4F, nominally Li0.97Cr0.01V0.95Al0.01Nb0.02PO4F0.97, is prepared by Chromium (Cr) doping on lithium site and Al-Nb co-doping on vanadium site via a conventional carbothermal reduction (CTR) route. The crystallographic lattice volume, particle size and morphology are not obviously changed comparing with un-doped LiVPO4F. However, the high rate and lifetime cycling performances are noticeably improved although the capacities at very low currents are slightly decreased. The reversible capacity at 1/10 C, 1 C, 2 C and 4 C of the pristine LiVPO4F is 143 mA h g-1, 99 mA h g-1, 86 mA h g-1 and 70 mA h g-1, respectively, while that of the doped counterpart is 138 mA h g-1, 102 mA h g-1, 95 mA h g-1 and 82 mA h g-1, respectively. The capacity retention after 100 galvanostatic cycles at 1.5 C is enhanced from 85.4% to 90.9% by such multi-cations doping. Moreover, the initial coulombic efficiency is significantly increased from 81.8% to 90.3% as well.

  19. Atomic origin of 3d(9)4?f(1) configuration in La(3+) solids.

    PubMed

    Yu, S-W; Carpenter, M H; Ponce, F; Friedrich, S; Lee, J-S

    2015-10-14

    We have studied the excited electronic structure of LaBr3(Ce) scintillator by soft x-ray spectroscopy such as x-ray absorption spectroscopy (XAS) and x-ray emission spectroscopy (XES). The La 3d XAS and XES spectra of LaBr3(Ce) are compared with those of other La(3+)?solids (LaF3, La2O3, and La metal). From this comparison, it turns out that the La 3d XAS and XES spectra from all the La(3+) solids considered here appear at almost the same energy, even though the corresponding binding energies of the 3d core holes determined by XPS (x-ray photoelectron spectroscopy) are very different. As a result, we argue that the atomic nature of the 3d?4f configuration created by 3d?4f? ? 3d?4f x-ray absorption process in La(3+) solids is maintained via the localized 4?f?(1) state, which screens the 3d core holes differently from one La(3+) solid to another. PMID:26401640

  20. 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

  1. 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

    ... Federal Aviation Administration is issuing this notice to advise the public that a Draft Environmental... Federal Aviation Administration Notice of Availability of Draft Environmental Impact Statement (DEIS), Draft Section 4(f) Evaluation, Notice of ANILCA Title XI evaluation, and Notice of Public Comment...

  2. 28 CFR 55.5 - Coverage under section 4(f)(4).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 28 Judicial Administration 2 2014-07-01 2014-07-01 false Coverage under section 4(f)(4). 55.5 Section 55.5 Judicial Administration DEPARTMENT OF JUSTICE (CONTINUED) IMPLEMENTATION OF THE PROVISIONS OF THE VOTING RIGHTS ACT REGARDING LANGUAGE MINORITY GROUPS Nature of Coverage 55.5 Coverage...

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

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 28 Judicial Administration 2 2012-07-01 2012-07-01 false Relationship between section 4(f)(4) and section 203(c). 55.8 Section 55.8 Judicial Administration DEPARTMENT OF JUSTICE (CONTINUED) IMPLEMENTATION OF THE PROVISIONS OF THE VOTING RIGHTS ACT REGARDING LANGUAGE MINORITY GROUPS Nature of Coverage 55.8 Relationship between section...

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

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 28 Judicial Administration 2 2011-07-01 2011-07-01 false Coverage under section 4(f)(4). 55.5 Section 55.5 Judicial Administration DEPARTMENT OF JUSTICE (CONTINUED) IMPLEMENTATION OF THE PROVISIONS OF THE VOTING RIGHTS ACT REGARDING LANGUAGE MINORITY GROUPS Nature of Coverage 55.5 Coverage...

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

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 28 Judicial Administration 2 2013-07-01 2013-07-01 false Coverage under section 4(f)(4). 55.5 Section 55.5 Judicial Administration DEPARTMENT OF JUSTICE (CONTINUED) IMPLEMENTATION OF THE PROVISIONS OF THE VOTING RIGHTS ACT REGARDING LANGUAGE MINORITY GROUPS Nature of Coverage 55.5 Coverage...

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

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 28 Judicial Administration 2 2010-07-01 2010-07-01 false Coverage under section 4(f)(4). 55.5 Section 55.5 Judicial Administration DEPARTMENT OF JUSTICE (CONTINUED) IMPLEMENTATION OF THE PROVISIONS OF THE VOTING RIGHTS ACT REGARDING LANGUAGE MINORITY GROUPS Nature of Coverage 55.5 Coverage...

  7. Extraction of Overt Verbal Response from the Acoustic Noise in a Functional Magnetic Resonance Imaging Scan by Use of Segmented Active Noise Cancellation

    PubMed Central

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

    2013-01-01

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

  8. 4f bands in Ce heavy fermions and mixed valent compounds at T {much_gt} T{sub K}

    SciTech Connect

    Andrews, A.B.; Joyce, J.J.; Arko, A.J.; Thompson, J.D.; Tang, J.; Fisk, Z.; Lawrence, J.M.; Riseborough, P.; Canfield, P.C.

    1994-08-01

    We report evidence of 4f band character in Ce 4f states at {Tau}{much_gt}{Tau}{sub K} using the technique of high-resolution angle-resolved resonant photoemission. The Ce intermetallic compound CePt{sub +x} was grown and studied in situ by the method of MBE and was characterized by LEED, XPS and XAS. These new findings would suggest a need for a reexamination of 4f photoemission in Ce compounds.

  9. Droplets Acoustics

    E-print Network

    Dahan, Raphael; Carmon, Tal

    2015-01-01

    Contrary to their capillary resonances (Rayleigh, 1879) and their optical resonances (Ashkin, 1977), droplets acoustical resonances were rarely considered. Here we experimentally excite, for the first time, the acoustical resonances of a droplet that relies on sound instead of capillary waves. Droplets vibrations at 37 MHz rates and 100 quality factor are optically excited and interrogated at an optical threshold of 68 microWatt. Our vibrations span a spectral band that is 1000 times higher when compared with drops previously-studied capillary vibration.

  10. Droplets Acoustics

    E-print Network

    Raphael Dahan; Leopoldo L. Martin; Tal Carmon

    2015-08-30

    Contrary to their capillary resonances (Rayleigh, 1879) and their optical resonances (Ashkin, 1977), droplets acoustical resonances were rarely considered. Here we experimentally excite, for the first time, the acoustical resonances of a droplet that relies on sound instead of capillary waves. Droplets vibrations at 37 MHz rates and 100 quality factor are optically excited and interrogated at an optical threshold of 68 microWatt. Our vibrations span a spectral band that is 1000 times higher when compared with drops previously-studied capillary vibration.

  11. 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.

  12. Acoustic Simulation COMP 768 Presentation

    E-print Network

    Lin, Ming C.

    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

  13. Tapered labyrinthine acoustic metamaterials for broadband impedance Yangbo Xie, Adam Konneker, Bogdan-Ioan Popa, and Steven A. Cummera)

    E-print Network

    Cummer, Steven A.

    metamaterials show potential as building blocks for a wide range of acoustic wave manipulation and imaging include transformation acoustic devices,18 acoustic diffraction gratings, acoustic holography, and other a long wavelength approximation, the acoustic wave equation can be expressed as @2 p @2f @ ln Sf @f

  14. Quantitative Thermo-acoustics and related problems Guillaume Bal

    E-print Network

    Biasutti, Michela

    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

  15. Evaluation of Transient Elastography, Acoustic Radiation Force Impulse Imaging (ARFI), and Enhanced Liver Function (ELF) Score for Detection of Fibrosis in Morbidly Obese Patients

    PubMed Central

    Karlas, Thomas; Dietrich, Arne; Peter, Veronica; Wittekind, Christian; Lichtinghagen, Ralf; Garnov, Nikita; Linder, Nicolas; Schaudinn, Alexander; Busse, Harald; Prettin, Christiane; Keim, Volker; Trltzsch, Michael; Schtz, Tatjana; Wiegand, Johannes

    2015-01-01

    Background Liver fibrosis induced by non-alcoholic fatty liver disease causes peri-interventional complications in morbidly obese patients. We determined the performance of transient elastography (TE), acoustic radiation force impulse (ARFI) imaging, and enhanced liver fibrosis (ELF) score for fibrosis detection in bariatric patients. Patients and Methods 41 patients (median BMI 47 kg/m2) underwent 14-day low-energy diets to improve conditions prior to bariatric surgery (day 0). TE (M and XL probe), ARFI, and ELF score were performed on days -15 and -1 and compared with intraoperative liver biopsies (NAS staging). Results Valid TE and ARFI results at day -15 and -1 were obtained in 49%/88% and 51%/90% of cases, respectively. High skin-to-liver-capsule distances correlated with invalid TE measurements. Fibrosis of liver biopsies was staged as F1 and F3 in n = 40 and n = 1 individuals. However, variations (median/range at d-15/-1) of TE (4.6/2.675 and 6.7/2.921.3 kPa) and ARFI (2.1/0.73.7 and 2.0/0.73.8 m/s) were high and associated with overestimation of fibrosis. The ELF score correctly classified 87.5% of patients. Conclusion In bariatric patients, performance of TE and ARFI was poor and did not improve after weight loss. The ELF score correctly classified the majority of cases and should be further evaluated. PMID:26528818

  16. 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.

  17. 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

  18. 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.

  19. 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.

  20. Competition between 3d and 4f magnetism in Ce2Fe2S5

    NASA Astrophysics Data System (ADS)

    Schneidewind, A.; Mills, A. M.; Schnelle, W.; Stockert, O.; Ouladdiaf, B.; Ruck, M.

    2007-03-01

    Magnetic susceptibility measurements and neutron powder diffraction were performed on the rare-earth transition-metal sulfide Ce2Fe2S5 to study the effect of the substitution of nonmagnetic La(4f0) by Ce4f1). Ce2Fe2S5, which is isostructural to La2Fe2S5, contains Fe ions within chains of iron-sulfur octahedra and tetrahedra that are interconnected by Ce ions. Two antiferromagnetic phases, both with the propagation vector ?=({1}/{2} {1}/{2} 0), are observed: at 5 K?T?80 K ordering of the Fe moments is found; at T?5 K the Ce ions also participate in the magnetic ordering.

  1. Photochromism and Photomagnetism of a 3d-4f Hexacyanoferrate at Room Temperature.

    PubMed

    Cai, Li-Zhen; Chen, Qing-Song; Zhang, Cui-Juan; Li, Pei-Xin; Wang, Ming-Sheng; Guo, Guo-Cong

    2015-09-01

    Polycyanometallate compounds with both photochromism and photomagnetism have appealing applications in optical switches and memories, but such optical behaviors were essentially restricted to the cryogenic temperature. We realized, for the first time, the photochromism and photomagnetism of 3d-4f hexacyanoferrates at room temperature (RT) in [Eu(III)(18C6)(H2O)3]Fe(III)(CN)62H2O (18C6 = 18-crown-6). Photoinduced electron transfer (PET) from crown to Fe(III) yields long-lived charge-separated species at RT in air in the solid state and also weakens the magnetic susceptibility significantly. The PET mechanism and changing trend of photomagnetism differ significantly from those reported for known 3d-4f hexacyanoferrates. This work not only develops a new type of inorganic-organic hybrid photochromic material but opens a new avenue for RT photomagnetic polycyanometallate compounds. PMID:26284651

  2. 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.

  3. 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.

  4. Transitions between the 4 f -core-excited states in Ir16 +,Ir17 +, and Ir18 + ions for clock applications

    NASA Astrophysics Data System (ADS)

    Safronova, U. I.; Flambaum, V. V.; Safronova, M. S.

    2015-08-01

    Iridium ions near 4 f -5 s level crossings are the leading candidates for a new type of atomic clocks with a high projected accuracy and a very high sensitivity to the temporal variation of the fine structure constant ? . To identify spectra of these ions in experiment accurate calculations of the spectra and electromagnetic transition probabilities should be performed. Properties of the 4 f -core-excited states in Ir16 +,Ir17 +, and Ir18 + ions are evaluated using relativistic many-body perturbation theory and Hartree-Fock-relativistic method (COWAN code). We evaluate excitation energies, wavelengths, oscillator strengths, and transition rates. Our large-scale calculations included the following set of configurations: 4 f145 s ,4 f145 p ,4 f135 s2,4 f135 p2,4 f135 s 5 p ,4 f125 s25 p , and 4 f125 s 5 p2 in Pm-like Ir16 +; 4 f14,4 f135 s ,4 f135 p ,4 f125 s2,4 f125 s 5 p , and 4 f125 p2 in Nd-like Ir17 +; and 4 f13,4 f125 s ,4 f125 p ,4 f115 s2 , and 4 f115 s 5 p in Pr-like Ir18 +. The 5 s -5 p transitions are illustrated by the synthetic spectra in the 180-200 range. Large contributions of magnetic-dipole transitions to lifetimes of low-lying states in the region below 2.5 Ry are demonstrated.

  5. 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 adipose tissue (VAT) were determined by MRI and hepatic lipid content by magnetic resonance spectroscopy decreased hepatic lipid content and increased the numbers of small adipocytes (P , 0.05) and phosphorylation

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

    E-print Network

    Physica Scripta. Vol. 71, 502506, 2005 Determination of the Li I 4d4f Energy Separation Using Active Spectroscopy K. Tsigutkin*,1 , E. Stambulchik1 , Y. Maron1 and A. Tauschwitz2 1 Faculty of Physics knowledge of the Lii 4d4f energy separation is essential for the determination of electric fields

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  8. Enhanced Acoustic Emission in Relation to the Acoustic Halo Surrounding Active Region 11429

    NASA Astrophysics Data System (ADS)

    Hanson, Chris S.; Donea, Alina C.; Leka, K. D.

    2015-08-01

    The use of acoustic holography in the high-frequency p-mode spectrum can resolve the source distributions of enhanced acoustic emissions within halo structures surrounding active regions. In doing so, statistical methods can then be applied to ascertain relationships with the magnetic field. This is the focus of this study. The mechanism responsible for the detected enhancement of acoustic sources around solar active regions has not yet been explained. Furthermore the relationship between the magnetic field and enhanced acoustic emission has not yet been comprehensively examined. We have used vector magnetograms from the Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics Observatory (SDO) to image the magnetic-field properties in the halo. We have studied the acoustic morphology of an active region, with a complex halo and "glories", and we have linked some acoustic properties to the magnetic-field configuration. In particular, we find that acoustic sources are significantly enhanced in regions of intermediate field strength with inclinations no different from the distributions found in the quiet Sun. Additionally, we have identified a transition region between the active region and the halo, in which the acoustic-source power is hindered by inclined fields of intermediate field strength. Finally, we have compared the results of acoustic-emission maps, calculated from holography, and the commonly used local acoustic maps, finding that the two types of maps have similar properties with respect to the magnetic field but lack spatial correlation when examining the highest-powered regions.

  9. Utilizing 3d-4f magnetic interaction to slow the magnetic relaxation of heterometallic complexes.

    PubMed

    Li, Xiao-Lei; Min, Fan-Yong; Wang, Chao; Lin, Shuang-Yan; Liu, Zhiliang; Tang, Jinkui

    2015-05-01

    The synthesis, structural characterization, and magnetic properties of four related heterometallic complexes with formulas [Dy(III)2Co(II)(C7H5O2)8]6H2O (1), [Dy(III)2Ni(II)(C7H5O2)8](C7H6O2)2 (2), Tb(III)2Co(II)(C7H5O2)8 (3), and Dy(III)2Cd(II)(C7H5O2)8 (4) were reported. Each of complexes has a perfectly linear arrangement of the metal ions with two terminal Ln(III) (Ln(III) = Dy(III), Tb(III)) ions and one central M(II) (M(II) = Co(II), Ni(II), Cd(II)) ion. It was found that 1-3 displayed obvious magnetic interactions between the spin carriers according to the direct current (dc) susceptibility measurements. Alternating current (ac) magnetic susceptibility measurements indicate that complexes 1-4 all exhibit single-molecule magnet (SMM) behavior, while the replacement of the diamagnetic Cd(II) by paramagnetic ions leads to a significant slowing of the relaxation thanks to the magnetic interactions between 3d and 4f ions, resulting in higher relaxation barrier for complexes 1 and 2. Moreover, both Dy2Co and Dy2Ni compounds exhibit dual relaxation pathways that may originate from the single ion behavior of individual Dy(III) ions and the coupling between Dy(III) and Co(II)/Ni(II) ions, respectively, which can be taken as the feature of 3d-4f SMMs. The Ueff for 1 of 127 K is a relatively high value among the reported 3d-4f SMMs. The results demonstrate that the magnetic coupling between 3d and 4f ions is crucial to optimize SMM parameters. The synthetic approach illustrated in this work represents an efficient route to design nd-4f based SMMs via incorporating suitable paramagnetic 3d and even 4d and 5d ions into the d-f system. PMID:25906391

  10. 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.

  11. 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 Cdiz.

  12. 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 (11.4 kHz), a helmet, earmuffs, and earplugs used together attenuated perceived sound by 5563 dB, whereas the attenuation provided by the conventional devices alone was substantially less: 3037 dB for earmuffs, 2528 dB for earplugs, and 3941 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 6065 dB SPL. Even greater reductions in noise should be achievable by isolating the body from the surrounding noise field. PMID:11206150

  13. 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.

  14. 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.

  15. 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.

  16. 4-[F-18]fluoroproline: A potential tracer for collagen synthesis. Radiosynthesis and biological evaluation

    SciTech Connect

    Hamacher, K.; Herz, M.; Truckenbrodt, R.

    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.; Huang, Jin

    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. 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.

  19. 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.

  20. Basic Properties of Eu2+ 5d-4f Luminescence in SiO2 Glass Matrix

    NASA Astrophysics Data System (ADS)

    Fujimoto, Yutaka; Yanagida, Takayuki; Futami, Yoshisuke; Fukuda, Kentaro; Koshimizu, Masanori

    Basic luminescence and scintillation properties of Eu2+ 5d-4f luminescence in SiO2 glass were studied with photoluminescence, decay time profile, radioluminescence and pulse height spectra measurements. When both UV light and alpha-ray excited to the glass, intense blue emission band was observed, which is due to the Eu2+ 4f65d-4f7(8S7/2) transition. Fluorescence quantum efficiency of the Eu2+ 5d-4f transitions was calculated to be more than 95%, and the value of two decay component was 774 ns (77%) and 1730 ns (23%). Relative scintillation light output was about 110% compared with that of reference lithium silicate glass (GS20) scintillator.

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

    NASA Astrophysics Data System (ADS)

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

    2011-11-01

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

  2. Experimental and theoretical investigations of four 3d-4f butterfly single-molecule magnets.

    PubMed

    Zou, Hua-Hong; Sheng, Liang-Bing; Liang, Fu-Pei; Chen, Zi-Lu; Zhang, Yi-Quan

    2015-11-14

    The syntheses, structures, and characterization of four 3d-4f butterfly clusters are described. With different polyhydroxy Schiff-base ligands 2-(((2-hydroxy-3-methoxyphenyl)methylene)amino)-2-(hydroxymethyl)-1,3-propanediol (H4L1) and 2-(2,3-dihydroxpropyliminomethyl)-6-methoxyphenol (H3L2), three heterotetranuclear NiLn complexes (NiDy-L1 (1), NiTb-L2 (2), NiDy-L2 (3)) and one heterohexanuclear CoDy complex (4) were obtained. The three heterotetranuclear NiLn complexes display a central planar butterfly topology. The heterohexanuclear complex was built from butterfly CoDy clusters and two Dy(III) ions by the bridging of pivalate. The vertices of the body positions of the butterfly are occupied by transition metal ions in all four complexes. Magnetic analyses indicate that the complexes exhibit typical single-molecule magnet behaviour with anisotropy barriers of 33.7 cm(-1), 60.3 cm(-1), 39.6 cm(-1), and 18.4 cm(-1) for 1-4, respectively. Ab initio calculations were performed on these complexes, and the low lying electronic structure of each Ln(III) (Ln = Dy, Tb) ion and the magnetic interactions were determined. It was found that the two Ln ions may have much more contribution to the total relaxation barrier through the stronger 3d-4f exchange couplings compared to weak Ln-Ln interactions. PMID:26443303

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

    E-print Network

    Pablo, Buenafama Aleman

    2004-11-15

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

  4. Common Variants of Cytochrome P450 4F2 Exhibit Altered Vitamin E-?-Hydroxylase Specific Activity12

    PubMed Central

    Bardowell, Sabrina A.; Stec, David E.; Parker, Robert S.

    2010-01-01

    Human cytochrome P450 4F2 (CYP4F2) catalyzes the ?-hydroxylation of the side chain of tocopherols (TOH) and tocotrienols (T3), the first step in their catabolism to polar metabolites excreted in urine. CYP4F2, in conjunction with ?-TOH transfer protein, results in the conserved phenotype of selective retention of ?-TOH. The purpose of this work was to determine the functional consequences of 2 common genetic variants in the human CYP4F2 gene on vitamin E-?-hydroxylase specific activity using the 6 major dietary TOH and T3 as substrate. CYP4F2-mediated ?-hydroxylase specific activity was measured in microsomal preparations from insect cells that express wild-type or polymorphic variants of the human CYP4F2 protein. The W12G variant exhibited a greater enzyme specific activity (pmol product ? min?1 ? pmol CYP4F2?1) compared with wild-type enzyme for both TOH and T3, 230275% of wild-type toward ?, ?, and ?-TOH and 350% of wild-type toward ?, ?, and ?-T3. In contrast, the V433M variant had lower enzyme specific activity toward TOH (4266% of wild type) but was without a significant effect on the metabolism of T3. Because CYP4F2 is the only enzyme currently shown to metabolize vitamin E in humans, the observed substrate-dependent alterations in enzyme activity associated with these genetic variants may result in alterations in vitamin E status in individuals carrying these mutations and constitute a source of variability in vitamin E status. PMID:20861217

  5. Surface and bulk 4f-photoemission spectra of CeIn{sub 3} and CeSn{sub 3}

    SciTech Connect

    Kim, H.; Tjernberg, O.; Chiaia, G.; Kumigashira, H.; Takahashi, T.; Duo, L.; Sakai, O.; Kasaya, M.; Lindau, I.

    1997-07-01

    Resonant photoemission spectroscopy was performed on CeIn{sub 3} and CeSn{sub 3} at the 4d-4f and 3d-4f core thresholds. Using the different surface sensitivity between the two photon energies, surface and bulk 4f-photoemission spectra were derived for both compounds. With the noncrossing approximation of the Anderson impurity model, the 4d-4f resonant spectra together with the surface and bulk spectra were self-consistently analyzed to obtain the microscopic parameters such as the 4f-electron energy and the hybridization strength with conduction electrons. The result shows a substantial difference in these parameters between the surface and the bulk, indicating that it is important to take into account the surface effect in analyzing photoemission spectra of Ce compounds. It is also found that the 4f surface core-level shift is different between CeIn{sub 3} and CeSn{sub 3}. {copyright} {ital 1997} {ital The American Physical Society}

  6. 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 mAhg?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

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. Automation and system integration of scanning tomographic acoustic microscope.

    PubMed

    Kent, S D; Lee, H

    1997-01-01

    The Scanning Tomographic Acoustic Microscope (STAM) is an instrument capable of performing subsurface imaging of microscopic specimens. Designed around the Scanning Laser Acoustic Microscope (SLAM), the STAM incorporates numerous hardware and software advances which allow automated imaging of the acoustic properties of thick specimens at high resolution. With these modifications the STAM is shown to be capable of image formation for tissue characterization and nondestructive evaluation (NDE) of microscopic specimens. This paper describes the design and operation of the STAM hardware, and software algorithms developed to permit high resolution imaging. Examples are provided to demonstrate the capability of multiple angle and multiple frequency tomographic reconstructions. PMID:9475432

  12. The Sounds of Nanoscience: Acoustic STM Analogues

    ERIC Educational Resources Information Center

    Euler, Manfred

    2013-01-01

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

  13. The VMI study on angular distribution of ejected electrons from Eu 4f76p1/26d autoionizing states

    NASA Astrophysics Data System (ADS)

    Zhang, Kai; Shen, Li; Dong, Cheng; Dai, Chang-Jian

    2015-10-01

    The combination of a velocity mapping imaging technique and mathematical transformation is adopted to study the angular distribution of electrons ejected from the Eu 4f76p1/26d autoionizing states, which are excited with a three-step excitation scheme via different Eu 4f76s6d 8 DJ (J = 5/2, 7/2, and 9/2) intermediate states. In order to determine the energy dependence of angular distribution of the ejected electrons, the anisotropic parameters are measured in the spectral profile of the 6p1/26d autoionizing states by tuning the wavelength of the third-step laser across the ionic resonance lines of the Eu 6s+ ? 6p+. The configuration interaction is discussed by comparing the angular distributions of ejected electrons from the different states. The present study reveals the profound variations of anisotropic parameters in the entire region of autoionization resonance, highlighting the complicated nature of the autoionization process for the lowest member of 6p1/26d autoionization series. Project supported by the National Natural Science Foundation of China (Grant No. 11174218).

  14. Conduction band states and the 5d-4f laser transition of rare earth ion dopants

    SciTech Connect

    Payne, S.A.; Marshall, C.D.; Bayramian, A.; Lawson, J.K.

    1996-12-31

    We discuss how the interactions of the 5d orbital with the conduction band of the host medium play a crucial role in determining whether rare earth containing materials can serve as useful laser materials, based on their 5d-4f transition. To explore this issue, we examine the pump-probe spectra of Sm[sup 2+], Eu[sup 2+], and Ce[sup 3+] dopants in various fluoride and chloride crystals. In addition we suggest that the luminescence properties are also profoundly impacted by this interaction. The outstanding UV laser performance achieved by the Ce:LiSrAlF[sub 6] crystal is rationalized in terms of the reduced overlap of conduction band states with the cerium ions.

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

    SciTech Connect

    Thompson, Joe E; Nair, S; Stockert, O; Witte, U; Nicklas, M; Schedler, R; Bianchi, A; Fisk, Z; Wirth, S; Steglich, K

    2009-01-01

    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.

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

    SciTech Connect

    Kroencke, Thomas J. Kluner, Claudia; Hamm, Bernd; Gauruder-Burmester, Annett

    2007-04-15

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

  17. 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

  18. 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

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

    NASA Astrophysics Data System (ADS)

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

    2012-02-01

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

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

    PubMed

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

    2012-02-15

    Spectral analysis of Nd(III) complexes with some amino acids viz.; glycine, l-alanine, l-phenylalanine and l-aspartic acid in the presence and absence of Ca(2+) was carried out in some organic solvents; CH(3)OH, CH(3)CN, DMF and dioxane using comparative absorption spectra of 4f-4f transitions. The study was carried out by evaluating various energy interaction parameters like Slator-Condon (F(k)), Lande factor (?(4f)), nephelauxetic ratio (?), bonding parameter (b(1/2)), percent-covalency (?) by applying partial and multiple regression analysis. The values of oscillator strength (P(obs)) and Judd-Ofelt electric dipole intensity parameter T(?) (?=2, 4, 6) for different 4f-4f transitions have been calculated. On analysis of the variation of the various energy interaction parameters as well as the changes in the oscillator strength (P(obs)) and T(?) values, reveal the mode of binding with the different ligands. Kinetic studies for the complexation of Nd(III):glycine:Ca(II) have also been discussed at different temperatures in DMF medium and from it the values of activation energy (E(a)) and thermodynamic parameters like ?H, ?S and ?G for the complexation are evaluated. PMID:22169029

  1. Holographic acoustic elements for manipulation of levitated objects.

    PubMed

    Marzo, Asier; Seah, Sue Ann; Drinkwater, Bruce W; Sahoo, Deepak Ranjan; Long, Benjamin; Subramanian, Sriram

    2015-01-01

    Sound can levitate objects of different sizes and materials through air, water and tissue. This allows us to manipulate cells, liquids, compounds or living things without touching or contaminating them. However, acoustic levitation has required the targets to be enclosed with acoustic elements or had limited manoeuvrability. Here we optimize the phases used to drive an ultrasonic phased array and show that acoustic levitation can be employed to translate, rotate and manipulate particles using even a single-sided emitter. Furthermore, we introduce the holographic acoustic elements framework that permits the rapid generation of traps and provides a bridge between optical and acoustical trapping. Acoustic structures shaped as tweezers, twisters or bottles emerge as the optimum mechanisms for tractor beams or containerless transportation. Single-beam levitation could manipulate particles inside our body for applications in targeted drug delivery or acoustically controlled micro-machines that do not interfere with magnetic resonance imaging. PMID:26505138

  2. Holographic acoustic elements for manipulation of levitated objects

    NASA Astrophysics Data System (ADS)

    Marzo, Asier; Seah, Sue Ann; Drinkwater, Bruce W.; Sahoo, Deepak Ranjan; Long, Benjamin; Subramanian, Sriram

    2015-10-01

    Sound can levitate objects of different sizes and materials through air, water and tissue. This allows us to manipulate cells, liquids, compounds or living things without touching or contaminating them. However, acoustic levitation has required the targets to be enclosed with acoustic elements or had limited manoeuvrability. Here we optimize the phases used to drive an ultrasonic phased array and show that acoustic levitation can be employed to translate, rotate and manipulate particles using even a single-sided emitter. Furthermore, we introduce the holographic acoustic elements framework that permits the rapid generation of traps and provides a bridge between optical and acoustical trapping. Acoustic structures shaped as tweezers, twisters or bottles emerge as the optimum mechanisms for tractor beams or containerless transportation. Single-beam levitation could manipulate particles inside our body for applications in targeted drug delivery or acoustically controlled micro-machines that do not interfere with magnetic resonance imaging.

  3. Holographic acoustic elements for manipulation of levitated objects

    PubMed Central

    Marzo, Asier; Seah, Sue Ann; Drinkwater, Bruce W.; Sahoo, Deepak Ranjan; Long, Benjamin; Subramanian, Sriram

    2015-01-01

    Sound can levitate objects of different sizes and materials through air, water and tissue. This allows us to manipulate cells, liquids, compounds or living things without touching or contaminating them. However, acoustic levitation has required the targets to be enclosed with acoustic elements or had limited manoeuvrability. Here we optimize the phases used to drive an ultrasonic phased array and show that acoustic levitation can be employed to translate, rotate and manipulate particles using even a single-sided emitter. Furthermore, we introduce the holographic acoustic elements framework that permits the rapid generation of traps and provides a bridge between optical and acoustical trapping. Acoustic structures shaped as tweezers, twisters or bottles emerge as the optimum mechanisms for tractor beams or containerless transportation. Single-beam levitation could manipulate particles inside our body for applications in targeted drug delivery or acoustically controlled micro-machines that do not interfere with magnetic resonance imaging. PMID:26505138

  4. 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.

  5. Opto-acoustic thrombolysis

    SciTech Connect

    Celliers, P.; Silva, L. Da; Glinsky, M.; London, R.; Maitland, D.; Matthews, D.; Fitch, P.

    2000-02-08

    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.

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

    SciTech Connect

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

    2011-10-01

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

  7. Effects of feedstock availability on the negative ion behavior in a C4F8 inductively coupled plasma

    NASA Astrophysics Data System (ADS)

    Zhao, Shu-Xia; Gao, Fei; Wang, Ya-Ping; Wang, You-Nian; Bogaerts, Annemie

    2015-07-01

    In this paper, the negative ion behavior in a C4F8 inductively coupled plasma (ICP) is investigated using a hybrid model. The model predicts a non-monotonic variation of the total negative ion density with power at low pressure (10-30 mTorr), and this trend agrees well with experiments that were carried out in many fluorocarbon (fc) ICP sources, like C2F6, CHF3, and C4F8. This behavior is explained by the availability of feedstock C4F8 gas as a source of the negative ions, as well as by the presence of low energy electrons due to vibrational excitation at low power. The maximum of the negative ion density shifts to low power values upon decreasing pressure, because of the more pronounced depletion of C4F8 molecules, and at high pressure (50 mTorr), the anion density continuously increases with power, which is similar to fc CCP sources. Furthermore, the negative ion composition is identified in this paper. Our work demonstrates that for a clear understanding of the negative ion behavior in radio frequency C4F8 plasma sources, one needs to take into account many factors, like the attachment characteristics, the anion composition, the spatial profiles, and the reactor configuration. Finally, a detailed comparison of our simulation results with experiments is conducted.

  8. Association of the CYP4F2 rs2108622 genetic polymorphism with hypertension: a meta-analysis.

    PubMed

    Luo, X-H; Li, G-R; Li, H-Y

    2015-01-01

    Previous case-control studies on the relationship between the CYP4F2 gene rs2108622 polymorphism and hypertension have produced contrasting results. In this study, we aimed to further evaluate the relationship between the CYP4F2 gene rs2108622 polymorphism and hypertension. We selected four case-control studies related to the CYP4F2 gene rs2108622 polymorphism and hypertension by searching PubMed, EMBase, the Chinese Biomedical Literature Database, and the Wanfang database. We utilized the Cochran Q-test and the I2 index to measure the heterogeneity across studies. To merge the odds ratio (OR) and the 95% confidence interval (95%CI), we utilized the fixed and random-effect models during the analyses. The present study included 1878 patients with hypertension and 1512 healthy control subjects. By meta-analysis, we did not find any association of the CYP4F2 gene rs2108622 polymorphism with hypertension in either genotype or allele distribution [AA+AG vs GG: OR = 1.18, 95%CI (0.91-1.54), P = 0.21; GG+AG vs AA: OR = 0.91, 95%CI (0.80-1.05), P = 0.20; A allele vs G allele: OR = 1.04, 95%CI (0.93-1.16), P = 0.53]. We concluded that the CYP4F2 gene rs2108622 polymorphism was not associated with hypertension. PMID:26634476

  9. 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

  10. Acoustic Neuroma Educational Video

    MedlinePLUS Videos and Cool Tools

    ... Treatment Options Summary Treatment Options Watch and Wait Radiation Microsurgery Acoustic Neuroma Decision Tree Questions for Your ... Treatment Options Summary Treatment Options Watch and Wait Radiation Microsurgery Acoustic Neuroma Decision Tree Questions for Your ...

  11. Cryogenic etching processes applied to porous low-k materials using SF6/C4F8 plasmas

    NASA Astrophysics Data System (ADS)

    Leroy, F.; Zhang, L.; Tillocher, T.; Yatsuda, K.; Maekawa, K.; Nishimura, E.; Lefaucheux, P.; de Marneffe, J.-F.; Baklanov, M. R.; Dussart, R.

    2015-11-01

    Cryogenic etching processes in SF6 and SF6/C4F8 plasmas were successfully applied to porous organosilicate glasses. Such materials are low-k candidates for advanced interconnects. Their integration is very challenging because of plasma induced damage. These two chemistries (SF6 and SF6/C4F8) have demonstrated a promising capability of significantly reducing the damage caused by plasma etching. Desorbed species were analyzed during the wafer warm-up from cryogenic to room temperature by in situ mass spectrometry. An equivalent damage layer (EDL) was evaluated by ex situ Fourier transform infrared (FTIR) spectroscopy and in situ ellipsometry. An anneal step at 350 C seems efficient to completely desorb the remaining CF x species. Anisotropic profiles were obtained using both chemistries. The selectivity is enhanced using SF6/C4F8 process at low temperature.

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1996-01-01

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

  14. Conformational specificity of the C4F6 SOD1 antibody; low frequency of reactivity in sporadic ALS cases.

    PubMed

    Ayers, Jacob I; Xu, Guilian; Pletnikova, Olga; Troncoso, Juan C; Hart, P John; Borchelt, David R

    2014-01-01

    Greater than 160 missense mutations in copper-zinc superoxide dismutase-1 (SOD1) can cause amyotrophic lateral sclerosis (ALS). These mutations produce conformational changes that reveal novel antibody binding epitopes. A monoclonal antibody, clone C4F6 - raised against the ALS variant G93A of SOD1, has been identified as specifically recognizing a conformation shared by many ALS mutants of SOD1. Attempts to determine whether non-mutant SOD1 adopts a C4F6-reactive conformation in spinal tissues of sporadic ALS (sALS) patients has produced inconsistent results. To define the epitope recognized by C4F6, we tested its binding to a panel of recombinant ALS-SOD1 proteins expressed in cultured cells, producing data to suggest that the C4F6 epitope minimally contains amino acids 90-93, which are normally folded into a tight hairpin loop. Multiple van der Waals interactions between the 90-93 loop and a loop formed by amino acids 37-42, particularly a leucine at position 38, form a stable structure termed the ?-plug. Based on published modeling predictions, we suggest that the binding of C4F6 to multiple ALS mutants of SOD1 occurs when the local structure within the ?-plug, including the loop at 90-93, is destabilized. In using the antibody to stain tissues from transgenic mice or humans, the specificity of the antibody for ALS mutant SOD1 was influenced by antigen retrieval protocols. Using conditions that showed the best discrimination between normal and misfolded mutant SOD1 in cell and mouse models, we could find no obvious difference in C4F6 reactivity to spinal motor neurons between sALS and controls tissues. PMID:24887207

  15. SIGNAL IMAGES PHYSIQUE Equipe SIGMAPhy-Signal Images Physique

    E-print Network

    Condat, Laurent

    gipsa-lab SIGMAPhy SIGNAL IMAGES PHYSIQUE Equipe SIGMAPhy-Signal Images Physique Underwater Acoustics : active and passive tomography, localisation (source/target) in complex environments. Optical LETI, CEA Saclay SIGMAPhy SIGNAL IMAGES PHYSIQUE Underground detection Tomography / Point Target SAR

  16. Morphology of anodically etched Si(111) surfaces: A structural comparison of NH{sub 4}F versus HF etching

    SciTech Connect

    Houbertz, R.; Memmert, U.; Behm, R.J.

    1994-11-01

    We present a comparative scanning tunneling microscopy (STM) study on the porous layer formation in two different fluoride containing solution, HF/ethanol and concentrated NH{sub 4}F solution. After etching in dilute HF solution the samples display a high density of micropores with typical diameters ranging from 5 to 25 nm, while NH{sub 4}F treated surfaces display shallow macropores of several hundred nm in diameter. These structural differences are discussed by comparing the different activity of both solutions for chemical etching of Si in the adsence of an external potential, which provides an additional reaction channel also under anodic conditions. 21 refs., 3 figs.

  17. Assignment of 4f->5d excitation spectra of Nd{sup 3+} in crystals using the simple model

    SciTech Connect

    Xia Shangda; Duan Changkui . E-mail: duanck@cqupt.edu.cn; Deng Quan; Ruan Gang

    2005-09-15

    The measured low-temperature (4f){sup 3}->(4f){sup 2}5d excitation spectra of Nd{sup 3+} doped in crystals YPO{sub 4}, CaF{sub 4} and LiYF{sub 4} [van Pieterson et al., Phys. Rev. B 65 (2002) 045113] are assigned and analyzed using the simple model proposed by Duan et al. [Phys. Rev. B 66 (2002) 155108] and Ning et al. [J. Alloy. Compd. 366 (2004) 34]. The agreement between theoretical and observed energies and intensities are acceptable, and at the same time the spectra are assigned in more detail.

  18. Acoustic metamaterial design and applications

    NASA Astrophysics Data System (ADS)

    Zhang, Shu

    The explosion of interest in metamaterials is due to the dramatically increased manipulation ability over light as well as sound waves. This material research was stimulated by the opportunity to develop an artificial media with negative refractive index and the application in superlens which allows super-resolution imaging. High-resolution acoustic imaging techniques are the essential tools for nondestructive testing and medical screening. However, the spatial resolution of the conventional acoustic imaging methods is restricted by the incident wavelength of ultrasound. This is due to the quickly fading evanescent fields which carry the subwavelength features of objects. By focusing the propagating wave and recovering the evanescent field, a flat lens with negative-index can potentially overcome the diffraction limit. We present the first experimental demonstration of focusing ultrasound waves through a flat acoustic metamaterial lens composed of a planar network of subwavelength Helmholtz resonators. We observed a tight focus of half-wavelength in width at 60.5 KHz by imaging a point source. This result is in excellent agreement with the numerical simulation by transmission line model in which we derived the effective mass density and compressibility. This metamaterial lens also displays variable focal length at different frequencies. Our experiment shows the promise of designing compact and light-weight ultrasound imaging elements. Moreover, the concept of metamaterial extends far beyond negative refraction, rather giving enormous choice of material parameters for different applications. One of the most interesting examples these years is the invisible cloak. Such a device is proposed to render the hidden object undetectable under the flow of light or sound, by guiding and controlling the wave path through an engineered space surrounding the object. However, the cloak designed by transformation optics usually calls for a highly anisotropic metamaterial, which make the experimental studies remain challenging. We present here the first practical realization of a low-loss and broadband acoustic cloak for underwater ultrasound. This metamaterial cloak is constructed with a network of acoustic circuit elements, namely serial inductors and shunt capacitors. Our experiment clearly shows that the acoustic cloak can effectively bend the ultrasound waves around the hidden object, with reduced scattering and shadow. Due to the non-resonant nature of the building elements, this low loss (6dB/m) cylindrical cloak exhibits excellent invisibility over a broad frequency range from 52 to 64 kHz in the measurements. The low visibility of the cloaked object for underwater ultrasound shed a light on the fundamental understanding of manipulation, storage and control of acoustic waves. Furthermore, our experimental study indicates that this design approach should be scalable to different acoustic frequencies and offers the possibility for a variety of devices based on coordinate transformation.

  19. Sensitivity and specificity enhancement in medical imaging

    E-print Network

    Combettes, Patrick Louis

    and the sensor technology. Multi-wave imaging: one single imaging system based on the combined use of two kinds;Multi-wave medical imaging 3 kinds of interactions between waves: Interaction of Wave 1 with tissues generates Wave 2: photo-acoustic imaging (V. Jugnon), thermo-acoustic imaging; Wave 1 can be tagged

  20. Microstress contrast in scanning electron acoustic microscopy of ceramics

    NASA Technical Reports Server (NTRS)

    Cantrell, John H.; Qian, Menglu

    1991-01-01

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

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

    SciTech Connect

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

    2012-04-01

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

  2. 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.

  3. Quantum Chaos and Quantum Magnetism with 4f-Submerged-Shell Atoms

    NASA Astrophysics Data System (ADS)

    Kotochigova, Svetlana; Makrides, Constantinos; Petrov, Alexander; Tiesinga, Eite

    2015-05-01

    We report on a theoretical investigation of the quantum level statistics of ultra-cold gases of open-4f-shell Er and Dy atoms based on a recently-developed computational model that can evaluate their weakly-bound molecular structure. A large interaction anisotropy between these atoms due to the large orbital angular momentum of their electrons creates a rich electronic structure. We find that this structure and their relatively large mass generates an extremely dense spectrum of rotational and vibrational levels near the dissociation limits for magnetic field strengths up to 100 Gauss. We analyzed these bound-state energy spectra and Feshbach resonance locations for signatures of chaos. For example, we find that in contrast to many other atomic systems these weakly-bound molecules already have a chaotic level distribution even in the absence of a magnetic field. We also report on the feasibility to detect quantum magnetism in a system where pairs of erbium or dysprosium are trapped in sites of an optical lattice. We predict the existence of spinor oscillations, where the population of magnetic sub levels oscillates in time due to the presence of anisotropic atomic interactions. Their periods can be used to characterize these interactions at zero and small magnetic field. Research at Temple University is supported by AFOSR (FA9550-14-1-0321) and NSF (No. PHY-1308573) grants.

  4. Synthesis, crystal structure, photoluminescence property of a series of 3d-4f coordination supramolecular complexes.

    PubMed

    Song, Jian; Li, Cheng-Ren; Xu, Qi; Xu, Xue-Ting; Sun, Li-Xian; Xing, Yong-Heng

    2015-11-01

    A series of 3d-4f heterobinuclear complexes were constructed by employing the 2,2'-bipy (2,2'-bipy=2,2'-bipyridine) ligand and corresponding metal ions (M(II)/Ln(III), M=Co(II), Cu(II) and Zn(II); Ln(III)=Nd(III), Sm(III), Eu(III) and Tb(III)). Elemental analyses, IR, UV-vis-NIR spectra, PXRD and single crystal X-ray diffraction analysis reveal that complexes 1-4, 5-8, and 9-12 are isomorphous, respectively. The zero-dimensional structures are further connected to 2D or 3D supramolecular network structures via extensive intermolecular hydrogen bonds. Luminescence studies for the heterobinuclear complexes containing Sm(III), Eu(III) and Tb(III) reveal that the chromophoric composed of Zn(II)/L may efficiently sensitize the luminescence of the rare earth cations which acts as an antenna, whereas the existence of Cu(II) leads to the quenching of the luminescence of Ln(III) ions. PMID:26056981

  5. Pressure-enhanced superconductivity in Eu3Bi2S4F4

    DOE PAGESBeta

    Luo, Yongkang; Zhai, Hui -Fei; Zhang, Pan; Xu, Zhu -An; Cao, Guang -Han; Thompson, J. D.

    2014-12-17

    The pressure effect on the newly discovered charge-transferred BiS2-based superconductor, Eu3Bi2S4F4, with a Tc of 1.5 K at ambient pressure, is investigated by transport and magnetic measurements. Accompanied with the enhancement of metallicity under pressures, the onset superconducting transition temperature increases abruptly around 1.0 GPa, reaching ~10.0 K at 2.26 GPa. Alternating current magnetic susceptibility measurements indicate that a new superconducting phase with a higher Tc emerges and dominates at high pressures. In the broad pressure window of 0.68GPa?p?2.00 GPa, the high-Tc phase coexists with the low-Tc phase. Hall effect measurements reveal a significant difference in electronic structures between themoretwo superconducting phases. As a result, our work devotes the effort to establish the commonality of pressure effect on the BiS2-based superconductors, and also uncovers the importance of electron carrier density in the high-Tc phase.less

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

    NASA Astrophysics Data System (ADS)

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

    2014-02-01

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

  7. Infratentorial Approach to Internal Acoustic Meatus

    PubMed Central

    Krajewski, Romuald; Kukwa, Andrzej

    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. ImagesFigure 1Figure 2figure 3 PMID:17171122

  8. Tissue elasticity using acoustic radiation force

    NASA Astrophysics Data System (ADS)

    Negron, Laura A.; Walker, William F.; Fernandez, Francisco J.

    2000-04-01

    We are developing a method that uses acoustic radiation force to image the stiffness of the vitreous body and other soft materials. This approach applies acoustic radiation force through a series of ultrasonic pulses to generate small displacements in tissue. Motion tracking techniques are used to measure the resultant displacement. This process can be repeated at a number of locations to acquire data for image formation. A series of acrylamide phantoms were constructed to test the proposed method. Phantom speed of sound and attenuation have been characterized and found to be close to that of the human vitreous. In this paper, we present acoustic radiation force images, which clearly distinguish phantoms of differing gel concentration. We also show time-displacement curves, which indicate a viscoelastic response for this material. The images presented show that acoustic radiation force can be used to image tissue mechanical properties including displacement, relative elasticity and relative viscosity. We present data that indicates maximum displacement is linearly proportional to the power transmitted by the system. Optical data was also collected to enable visualization of the displacement field.

  9. 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 Park, Sung Soo

    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 coreshell 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 coreshell 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.

  10. ACOUSTICAL STANDARDS NEWS.

    PubMed

    Blaeser, Susan B; Struck, Christopher J

    2015-11-01

    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 a catalog of Acoustical American National Standards. To receive a copy of the latest Standards catalog, 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 Catalog 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:26627807

  11. Photoacoustic imaging platforms for multimodal imaging.

    PubMed

    Kim, Jeesu; Lee, Donghyun; Jung, Unsang; Kim, Chulhong

    2015-04-01

    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

  12. 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

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

    PubMed Central

    Bitterman, Peter B.; Polunovsky, Vitaly A.

    2012-01-01

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

  14. Carbothermal reduction synthesis of carbon coated Na2FePO4F for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Cui, Dongming; Chen, Shasha; Han, Chang; Ai, Changchun; Yuan, Liangjie

    2016-01-01

    Carbon coated spherical Na2FePO4F particles with typical diameters from 500 nm to 1 ?m have been synthesized through an economical carbothermal reduction method with a simple apparatus. Mixed carbon source consists of citric acid and phenolic resin can form highly graphitized carbon and remarkably improve the electrical conductivity. When cycled against lithium, Na2FePO4F/C cathodes deliver maximum discharge capacity of 119 mAh g-1 at a low rate of 0.05 C. Reversible capacity of 110 mAh g-1, 74 mAh g-1 and 52 mAh g-1 can be obtained at 0.1 C, 1 C and 2 C rates, respectively. And after 30 cycles at 0.1 C, 91% of the discharge capacity can still be maintained. The electrochemical kinetic characteristic of electrode material is investigated by EIS and the apparent Li+ diffusion coefficient in the Li/Na2FePO4F system is evaluated to be as high as 1.152 10-11 cm2 s-1. This study demonstrates that the practical and economical synthesis process can be a promising way for industrial production of high performance Na2FePO4F/C electrode material for large-scale lithium ion batteries.

  15. Accessing perfluoroalkyl nickel(ii), (iii), and (iv) complexes bearing a readily attached [C4F8] ligand.

    PubMed

    Yu, S; Dudkina, Y; Wang, H; Kholin, K V; Kadirov, M K; Budnikova, Y H; Vicic, D A

    2015-11-10

    The [C4F8] ligand was shown to support well-defined terpyridyl nickel complexes in the +2 and +3 oxidation states. Notably, a cyclic voltammetry study of the nickel(iii) species indicates that an additional oxidation is accessible, providing a family of related fluoroalkyl nickel complexes spanning the +2 to +4 oxidation states. PMID:26072704

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

    SciTech Connect

    Lee, Hee Keun; Park, Hong-Joon; Lee, Kyu-Yup; Park, Rekil; Kim, Un-Kyung

    2010-06-04

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

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

    SciTech Connect

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

    2013-12-28

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

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

    PubMed

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

    2014-09-01

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

  19. 2011201120112011 2011 Symposium on Piezoelectricity, Acoustic waves, and Device Application

    E-print Network

    Chen, Baoquan

    ; Oscillators and Filters; Ultrasound Imaging, drug delivery and Therapy; Kirk Shung ( ) C. T. Chan://web.siat.ac.cn/spawda2011/ 1 2011 2011 12 9 -11 IEEE Theory of Piezoelectricity; Bulk and Surface Acoustic Waves; MEMS

  20. A new acoustic lens material for large area detectors in photoacoustic breast tomography

    E-print Network

    Xia, Wenfeng; van Hespen, Johan C G; Steenbergen, Wiendelt; Manohar, Srirang

    2013-01-01

    Acoustic lenses made of acrylic plastic (PMMA) have been used to enlarge the acceptance angle of sensitive large surface area detectors and improve lateral resolution. However, PMMA lenses introduce image artifacts due to ultrasound internal reflections within the lenses. In this work we investigated this issue proposing a new lens material Stycast 1090SI. We characterized the acoustic properties of the proposed material in comparison with PMMA. Detector performance using negative lenses with the two materials, was tested using finite element simulation and experiment. Further the image quality of a photoacoustic tomography system was studied using k-Wave simulation and experiment. Our acoustic characterization showed that Stycast 1090SI has tissue-like acoustic impedance, high speed of sound and low acoustic attenuation. Both acoustic lenses show significant enlargement of detector acceptance angle and lateral resolution improvement. However, image artifacts induced by acoustic lenses are reduced using the p...

  1. SBI-0640756 Attenuates the Growth of Clinically Unresponsive Melanomas by Disrupting the eIF4F Translation Initiation Complex.

    PubMed

    Feng, Yongmei; Pinkerton, Anthony B; Hulea, Laura; Zhang, Tongwu; Davies, Michael A; Grotegut, Stefan; Cheli, Yann; Yin, Hongwei; Lau, Eric; Kim, Hyungsoo; De, Surya K; Barile, Elisa; Pellecchia, Maurizio; Bosenberg, Marcus; Li, Jian-Liang; James, Brian; Hassig, Christian A; Brown, Kevin M; Topisirovic, Ivan; Ronai, Ze'ev A

    2015-12-15

    Disrupting the eukaryotic translation initiation factor 4F (eIF4F) complex offers an appealing strategy to potentiate the effectiveness of existing cancer therapies and to overcome resistance to drugs such as BRAF inhibitors (BRAFi). Here, we identified and characterized the small molecule SBI-0640756 (SBI-756), a first-in-class inhibitor that targets eIF4G1 and disrupts the eIF4F complex. SBI-756 impaired the eIF4F complex assembly independently of mTOR and attenuated growth of BRAF-resistant and BRAF-independent melanomas. SBI-756 also suppressed AKT and NF-?B signaling, but small-molecule derivatives were identified that only marginally affected these pathways while still inhibiting eIF4F complex formation and melanoma growth, illustrating the potential for further structural and functional manipulation of SBI-756 as a drug lead. In the gene expression signature patterns elicited by SBI-756, DNA damage, and cell-cycle regulatory factors were prominent, with mutations in melanoma cells affecting these pathways conferring drug resistance. SBI-756 inhibited the growth of NRAS, BRAF, and NF1-mutant melanomas in vitro and delayed the onset and reduced the incidence of Nras/Ink4a melanomas in vivo. Furthermore, combining SBI-756 and a BRAFi attenuated the formation of BRAFi-resistant human tumors. Taken together, our findings show how SBI-756 abrogates the growth of BRAF-independent and BRAFi-resistant melanomas, offering a preclinical rationale to evaluate its antitumor effects in other cancers. Cancer Res; 75(24); 5211-8. 2015 AACR. PMID:26603897

  2. Silicon etch using SF{sub 6}/C{sub 4}F{sub 8}/Ar gas mixtures

    SciTech Connect

    Bates, Robert L.; Stephan Thamban, P. L.; Goeckner, Matthew J.; Overzet, Lawrence J.

    2014-07-01

    While plasmas using mixtures of SF{sub 6}, C{sub 4}F{sub 8}, and Ar are widely used in deep silicon etching, very few studies have linked the discharge parameters to etching results. The authors form such linkages in this report. The authors measured the optical emission intensities of lines from Ar, F, S, SF{sub x}, CF{sub 2}, C{sub 2}, C{sub 3}, and CS as a function of the percentage C{sub 4}F{sub 8} in the gas flow, the total gas flow rate, and the bias power. In addition, the ion current density and electron temperature were measured using a floating Langmuir probe. For comparison, trenches were etched of various widths and the trench profiles (etch depth, undercut) were measured. The addition of C{sub 4}F{sub 8} to an SF{sub 6}/Ar plasma acts to reduce the availability of F as well as increase the deposition of passivation film. Sulfur combines with carbon in the plasma efficiently to create a large optical emission of CS and suppress optical emissions from C{sub 2} and C{sub 3}. At low fractional flows of C{sub 4}F{sub 8}, the etch process appears to be controlled by the ion flux more so than by the F density. At large C{sub 4}F{sub 8} fractional flows, the etch process appears to be controlled more by the F density than by the ion flux or deposition rate of passivation film. CF{sub 2} and C{sub 2} do not appear to cause deposition from the plasma, but CS and other carbon containing molecules as well as ions do.

  3. The Revised Human Liver Cytochrome P450 Pie: Absolute Protein Quantification of CYP4F and CYP3A Enzymes Using Targeted Quantitative Proteomics

    PubMed Central

    Michaels, Scott

    2014-01-01

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

  4. Images

    Cancer.gov

    Home News and Events Multimedia Library Images Images: Cancer Biology Image:Cell with DNA72 DPI|300 DPIDrawing depicting DNA molecule unwinding from a chromosome inside the nucleus of a cell. NHGRI>>View All Cancer Pathology/Imaging Image:Female

  5. AST Launch Vehicle Acoustics

    NASA Technical Reports Server (NTRS)

    Houston, Janice; Counter, D.; Giacomoni, D.

    2015-01-01

    The liftoff phase induces acoustic loading over a broad frequency range for a launch vehicle. These external acoustic environments are then used in the prediction of internal vibration responses of the vehicle and components which result in the qualification levels. Thus, predicting these liftoff acoustic (LOA) environments is critical to the design requirements of any launch vehicle. If there is a significant amount of uncertainty in the predictions or if acoustic mitigation options must be implemented, a subscale acoustic test is a feasible pre-launch test option to verify the LOA environments. The NASA Space Launch System (SLS) program initiated the Scale Model Acoustic Test (SMAT) to verify the predicted SLS LOA environments and to determine the acoustic reduction with an above deck water sound suppression system. The SMAT was conducted at Marshall Space Flight Center and the test article included a 5% scale SLS vehicle model, tower and Mobile Launcher. Acoustic and pressure data were measured by approximately 250 instruments. The SMAT liftoff acoustic results are presented, findings are discussed and a comparison is shown to the Ares I Scale Model Acoustic Test (ASMAT) results.

  6. A synthetic aperture acoustic prototype system

    NASA Astrophysics Data System (ADS)

    Luke, Robert H.; Bishop, Steven S.; Chan, Aaron M.; Gugino, Peter M.; Donzelli, Thomas P.; Soumekh, Mehrdad

    2015-05-01

    A novel quasi-monostatic system operating in a side-scan synthetic aperture acoustic (SAA) imaging mode is presented. This research project's objectives are to explore the military utility of outdoor continuous sound imaging of roadside foliage and target detection. The acoustic imaging method has several military relevant advantages such as being immune to RF jamming, superior spatial resolution as compared to 0.8-2.4 GHz ground penetrating radar (GPR), capable of standoff side and forward-looking scanning, and relatively low cost, weight and size when compared to GPR technologies. The prototype system's broadband 2-17 kHz LFM chirp transceiver is mounted on a manned all-terrain vehicle. Targets are positioned within the acoustic main beam at slant ranges of two to seven meters and on surfaces such as dirt, grass, gravel and weathered asphalt and with an intervening metallic chain link fence. Acoustic image reconstructions and signature plots result in means for literal interpretation and quantifiable analyses.

  7. AUDIO FORENSICS FROM ACOUSTIC REVERBERATION Hafiz Malik

    E-print Network

    Bucci, David J.

    AUDIO FORENSICS FROM ACOUSTIC REVERBERATION Hafiz Malik Department of Electrical and Computer be used in a forensic and ballistic setting. Index Terms-- Audio Forensics 1. INTRODUCTION The past few years have seen significant advances in image forensics [1]. At the same time, techniques

  8. 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.

  9. Acoustic rainbow trapping

    PubMed Central

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

    2013-01-01

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

  10. Measurements of electron attachment lineshapes and cross sections at ultra-low electron energies for CF2Cl2, c-C4F6, c-C4F8 and c-C7F14

    NASA Technical Reports Server (NTRS)

    Chutjian, A.; Alajajian, S. H.

    1987-01-01

    Electron-attachment cross sections are reported in the electron energy range 0-160 meV, and at energy resolutions of 7.0 and 7.5 meV (FWHM), for the molecules CF2Cl2 (dichlorodifluoromethane), c-C4F6 (perfluorocyclobutene), c-C4F8 (perfluorocyclobutane), and c-C7F14 (perfluoromethylcyclohexane). Use is made of the Kr photoionization method. Measured attachment lineshapes are deconvoluted from the spectral slit function, and are converted to cross sections by normalization through thermal attachment-rate constants. Comparisons are made with attachment cross sections derived from several independent sets of swarm-measured rate constants, and with collisional ionization (high-Rydberg attachment) data.

  11. Acoustic coupling of flames

    SciTech Connect

    Van Harten, A.; Kapila, A.K.; Matkowsky, B.J.

    1984-10-01

    In the limits of large activation energy and small Mach number, the full equations of reactive gas dynamics are reduced to a simpler set which is appropriate for studying acoustic interaction with slender flames. The model is used to study the interaction of a plane, steady flame with a normally incident acoustic wave. Explicit analytical expressions are obtained for the reflection and transmission coefficients, and, in two limiting cases, for the acoustically induced disturbance in the flame speed. 6 references.

  12. Studies on the complexation of Pr(III) and Nd(III) with glycyl-glycine (gly-gly) using spectral analysis of 4f-4f transitions and potentiometric titrations

    NASA Astrophysics Data System (ADS)

    Ranjana Devi, N.; Huidrom, Bimola; Rajmuhon Singh, N.

    2012-10-01

    The interaction of gly-gly with Pr(III) and Nd(III) have been studied in different aquated organic solvents like CH3OH, CH3CN, dioxane and DMF by using 4f-4f transitions spectra. Various energy interaction parameters like Slater Condon (Fk), Racah (Ek), Lande (?4f), nephelauxetic effect (?), bonding (b1/2) and percent covalency (?) parameters have been calculated to explain the nature of complexation. The intensity parameters like oscillator strength (P) and Judd-Ofelt parameters (T?, ? = 2, 4, 6) also support the mode of binding of gly-gly to metal ions. The results show that Pr(III) and Nd(III) with gly-gly form complexes by ionic linkages with carboxylate anion with weak covalency. The protonation constants and metal-ligand stability constants have also been determined by potentiometric measurements in aqueous medium at different temperatures (290, 300 and 310 K) at constant ionic strength, 0.1 mol dm-1. The results show the formation of metal-ligand complexes in the stoichiometric ratio 1:1. The stability of complexes is more in Nd(III) complexes as compared to Pr(III) complexes. Thermodynamic parameters (?G, ?H and ?S) of complexes were also calculated and the negative values of ?G and ?H show that the complex reactions are spontaneous and exothermic. The positive values of ?S indicate high stability of complex reactions which are enthalpy-driven.

  13. Acoustical CharacterizationAcoustical Characterization of Gunshotsof Gunshots

    E-print Network

    Maher, Robert C.

    Firearm Classification #12;Sound CharacteristicsSound Characteristics Acoustic behaviorAcoustic behavior depends upon:depends upon: Firearm type Projectile parameters Explosive load Distance

  14. 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.

  15. 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....

  16. Acoustic dispersive prism.

    PubMed

    Esfahlani, Hussein; Karkar, Sami; Lissek, Herve; Mosig, Juan R

    2016-01-01

    The optical dispersive prism is a well-studied element, which allows separating white light into its constituent spectral colors, and stands in nature as water droplets. In analogy to this definition, the acoustic dispersive prism should be an acoustic device with capability of splitting a broadband acoustic wave into its constituent Fourier components. However, due to the acoustical nature of materials as well as the design and fabrication difficulties, there is neither any natural acoustic counterpart of the optical prism, nor any artificial design reported so far exhibiting an equivalent acoustic behaviour. Here, based on exotic properties of the acoustic transmission-line metamaterials and exploiting unique physical behaviour of acoustic leaky-wave radiation, we report the first acoustic dispersive prism, effective within the audible frequency range 800?Hz-1300?Hz. The dispersive nature, and consequently the frequency-dependent refractive index of the metamaterial are exploited to split the sound waves towards different and frequency-dependent directions. Meanwhile, the leaky-wave nature of the structure facilitates the sound wave radiation into the ambient medium. PMID:26739504

  17. Simple acoustic multiplexer

    NASA Astrophysics Data System (ADS)

    Dobrzynski, L.; Zieli?ski, P.; Akjouj, A.; Sylla, B.

    2005-04-01

    Simple structures enabling the multiplexing of acoustic waves are presented. Such structures are constructed out of two monomode acoustic wires and two masses bound together, and to the wires by springs. We show analytically that these simple structures can transfer with selectivity and in one direction one acoustic wavelength from one wire to the other, leaving neighbor acoustic wavelengths unaffected. We give closed-form relations enabling to obtain the values of the relevant physical parameters for this multiplexing phenomena to happen at a chosen wavelength. Finally, we illustrate this general theory by an application.

  18. BDNF gene therapy induces auditory nerve survival and fiber sprouting in deaf Pou4f3 mutant mice.

    PubMed

    Fukui, H; Wong, H T; Beyer, L A; Case, B G; Swiderski, D L; Di Polo, A; Ryan, A F; Raphael, Y

    2012-01-01

    Current therapy for patients with hereditary absence of cochlear hair cells, who have severe or profound deafness, is restricted to cochlear implantation, a procedure that requires survival of the auditory nerve. Mouse mutations that serve as models for genetic deafness can be utilized for developing and enhancing therapies for hereditary deafness. A mouse with Pou4f3 loss of function has no hair cells and a subsequent, progressive degeneration of auditory neurons. Here we tested the influence of neurotrophin gene therapy on auditory nerve survival and peripheral sprouting in Pou4f3 mouse ears. BDNF gene transfer enhanced preservation of auditory neurons compared to control ears, in which nearly all neurons degenerated. Surviving neurons in treated ears exhibited pronounced sprouting of nerve fibers into the auditory epithelium, despite the absence of hair cells. This enhanced nerve survival and regenerative sprouting may improve the outcome of cochlear implant therapy in patients with hereditary deafness. PMID:23150788

  19. Acoustic superfocusing by solid phononic crystals

    SciTech Connect

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

    2014-12-08

    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. An acoustic filter based on layered structure

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

  1. New Sensors For Flow Velocity And Acoustics

    NASA Technical Reports Server (NTRS)

    Cho, Y. C.

    1991-01-01

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

  2. A Klein-Gordon acoustic theory

    SciTech Connect

    Anno, P.D.

    1992-12-01

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

  3. A Klein-Gordon acoustic theory

    SciTech Connect

    Anno, P.D.

    1992-12-01

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

  4. Ultra-rapid microwave synthesis of triplite LiFeSO4F Rajesh Tripathi,a

    E-print Network

    Ryan, Dominic

    tavorite precursor that forms on ultra-rapid microwave heating (10 min) of FeSO4$H2O/LiF. We proposeUltra-rapid microwave synthesis of triplite LiFeSO4F Rajesh Tripathi,a Guerman Popov,a Xiaoqi Sun microwave solvothermal technique which generates the precursor tavorite phase from the reaction of FeSO4$H2O

  5. Nuclear magnetic resonance of Al-27 in topaz, Al2SiO4/F, OH/2.

    NASA Technical Reports Server (NTRS)

    Tsang, T.; Ghose, S.

    1972-01-01

    The Al-27 nuclear quadrupolar coupling constant and asymmetry parameter (eta) in topaz have been determined to be 1.67 (plus or minus 0.03) MHz and 0.38 plus or minus 0.05, respectively. These values and the orientations of the principal axes are consistent with the Fe(3+) paramagnetic resonance data and with the symmetry of the AlO4F2 octahedron.

  6. High-resolution electron spectroscopy of lanthanide (Ce, Pr, and Nd) complexes of cyclooctatetraene: The role of 4f electrons

    SciTech Connect

    Kumari, Sudesh; Roudjane, Mourad; Hewage, Dilrukshi; Yang Dongsheng; Liu Yang

    2013-04-28

    Cerium, praseodymium, and neodymium complexes of 1,3,5,7-cyclooctatetraene (COT) complexes were produced in a laser-vaporization metal cluster source and studied by pulsed-field ionization zero electron kinetic energy spectroscopy and quantum chemical calculations. The computations included the second-order Moller-Plesset perturbation theory, the coupled cluster method with single, double, and perturbative triple excitations, and the state-average complete active space self-consistent field method. The spectrum of each complex exhibits multiple band systems and is assigned to ionization of several low-energy electronic states of the neutral complex. This observation is different from previous studies of M(COT) (M = Sc, Y, La, and Gd), for which a single band system was observed. The presence of the multiple low-energy electronic states is caused by the splitting of the partially filled lanthanide 4f orbitals in the ligand field, and the number of the low-energy states increases rapidly with increasing number of the metal 4f electrons. On the other hand, the 4f electrons have a small effect on the geometries and vibrational frequencies of these lanthanide complexes.

  7. Magneto-structural variety of new 3d-4f-4(5)d heterotrimetallic complexes.

    PubMed

    Visinescu, Diana; Alexandru, Maria-Gabriela; Madalan, Augustin M; Pichon, Cline; Duhayon, Carine; Sutter, Jean-Pascal; Andruh, Marius

    2015-10-14

    Three families of heterotrimetallic chains (type 1-type 3), with different topologies, have been obtained by reacting the 3d-4f complexes, [{Cu(L(1))}xLn(NO3)3] with x = 1 or 2, formed in situ by the reaction of Schiff-base bi-compartmental [Cu(II)(L(1))] complexes and lanthanide(iii) salts, with (NHBu3)3[M(CN)8] (M = Mo(V), W(V)). For type 1 series of compounds, 1-D coordination polymers, with the general formula [{Cu2(valpn)2Ln}{M(CN)8}]nH2OmCH3CN (where H2valpn = 1,3-propanediylbis(2-iminomethylene-6-methoxy-phenol), result from the association of trinuclear {CuLn(III)} moieties and [M(V)(CN)8](3-) anions acting as tri-connecting spacers [Ln = La (1), Ce (2), Eu (3), Tb (4), Ho (5), M = Mo; Ln = Tb (6), Ho (7), M = W; m = 0, n = 1.5 (7) and 2 (1-4, 6); n = 1, m = 1 (5)]. The type 2 family has the general formula [{Cu(valdp)Ln(H2O)4}{M(CN)8}]2H2OCH3CN (where H2valdp = 1,2-propanediylbis(2-iminomethylene-6-methoxy-phenol)) and also consists of heterotrimetallic chains involving binuclear {Cu(II)Ln(III)} units linked to [M(CN)8](3-) anions coordinating through two cyano groups [Ln = Gd (8), Tb (9), Dy (10); M = Mo; Ln = La (11), Gd (12), Tb (13), Dy (14); M = W]. With large Ln(III) ions (La(III) and Pr(III)), the type 3 family of heterotrimetallic compounds are assembled: [{Cu2(valdp)2Ln(H2O)4}{Mo(CN)8}]nCH3OHmCH3CN, n, m = 0, Ln = La (15); n = m = 1, Pr (16), in which the trinuclear {CuLn(III)} nodes are connected to [Mo(V)(CN)8](3-) anions that act as tetra-connecting spacers. For Tb(III) derivatives of the type 1 (compounds 4 and 6), the DC magnetic properties indicate a predominant ferromagnetic Cu(II)-Tb(III) interaction, while the AC magnetic susceptibility (in the presence of a static magnetic field, HDC = 3000 Oe) emphasize the slow relaxation of the magnetization (Ueff/kB = 20.55 K and ?0 = 5.5 10(-7) s for compound 4, Ueff/kBT = 15.1 K and ?0 = 1.5 10(-7) s for compound 6). A predominant ferromagnetic Cu(II)-Ln(III) interaction was also observed in the type 2 series (compounds 8-10 and 12-14) as a result of the magnetic coupling between copper(ii) and lanthanide(iii) ions via the phenoxo-bridge. The magnetic behavior for the La(III) derivatives reveals that weak ferromagnetic interactions are also operative between the Cu(II) and the 4d/5d centers. PMID:26199073

  8. Acoustic Heating Peter Ulmschneider

    E-print Network

    Ulmschneider, Peter

    Acoustic Heating Peter Ulmschneider lnstitut fiir Theoretische Astrophysik der Universitat waves are a viable and prevalent heating mechanism both in early- and in late-type stars. Acoustic heating appears to be a dominant mechanism for situations where magnetic fields are weak or absent

  9. Acoustic microstreaming applied to batch micromixing

    NASA Astrophysics Data System (ADS)

    Manasseh, Richard; Petkovic-Duran, Karolina; Tho, Paul; Zhu, Yonggang; Ooi, Andrew

    2006-01-01

    Experiments are presented in which acoustic microstreaming is investigated and applied to a batch micromixing case appropriate to a point-of-care pathology screening test. The flows presented can be created without complex engineering of contacts or surfaces in the microdevice, which could thus be made disposable. Fundamental flow patterns are measured with a micro-Particle-Image Velocimetry (micro-PIV) system, enabling a quantification of the fluiddynamical processes causing the flows. The design of micromixers based on this principle requires a quantification of the mixing. A simple technique based on digital image processing is presented that enables an assessment of the improvement in mixing due to acoustic microstreaming. The digital image processing technique developed was shown to be non-intrusive, convenient and able to generate useful quantitative data. Preliminary indications are that microstreaming can at least halve the time required to mix quantities of liquid typical of a point-of-care test, and significantly greater improvements seem feasible.

  10. Acoustic metamaterial for subwavelength edge detection

    NASA Astrophysics Data System (ADS)

    Molern, Miguel; Daraio, Chiara

    2015-08-01

    Metamaterials have demonstrated the possibility to produce super-resolved images by restoring propagative and evanescent waves. However, for efficient information transfer, for example, in compressed sensing, it is often desirable to visualize only the fast spatial variations of the wave field (carried by evanescent waves), as the one created by edges or small details. Image processing edge detection algorithms perform such operation, but they add time and complexity to the imaging process. Here we present an acoustic metamaterial that transmits only components of the acoustic field that are approximately equal to or smaller than the operating wavelength. The metamaterial converts evanescent waves into propagative waves exciting trapped resonances, and it uses periodicity to attenuate the propagative components. This approach achieves resolutions ~5 times smaller than the operating wavelength and makes it possible to visualize independently edges aligned along different directions.

  11. Acoustic metamaterial for subwavelength edge detection.

    PubMed

    Molern, Miguel; Daraio, Chiara

    2015-01-01

    Metamaterials have demonstrated the possibility to produce super-resolved images by restoring propagative and evanescent waves. However, for efficient information transfer, for example, in compressed sensing, it is often desirable to visualize only the fast spatial variations of the wave field (carried by evanescent waves), as the one created by edges or small details. Image processing edge detection algorithms perform such operation, but they add time and complexity to the imaging process. Here we present an acoustic metamaterial that transmits only components of the acoustic field that are approximately equal to or smaller than the operating wavelength. The metamaterial converts evanescent waves into propagative waves exciting trapped resonances, and it uses periodicity to attenuate the propagative components. This approach achieves resolutions ?5 times smaller than the operating wavelength and makes it possible to visualize independently edges aligned along different directions. PMID:26304739

  12. Acoustic metamaterial for subwavelength edge detection

    PubMed Central

    Molern, Miguel; Daraio, Chiara

    2015-01-01

    Metamaterials have demonstrated the possibility to produce super-resolved images by restoring propagative and evanescent waves. However, for efficient information transfer, for example, in compressed sensing, it is often desirable to visualize only the fast spatial variations of the wave field (carried by evanescent waves), as the one created by edges or small details. Image processing edge detection algorithms perform such operation, but they add time and complexity to the imaging process. Here we present an acoustic metamaterial that transmits only components of the acoustic field that are approximately equal to or smaller than the operating wavelength. The metamaterial converts evanescent waves into propagative waves exciting trapped resonances, and it uses periodicity to attenuate the propagative components. This approach achieves resolutions ?5 times smaller than the operating wavelength and makes it possible to visualize independently edges aligned along different directions. PMID:26304739

  13. Virtual acoustics displays

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

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

  14. Cochlear bionic acoustic metamaterials

    NASA Astrophysics Data System (ADS)

    Ma, Fuyin; Wu, Jiu Hui; Huang, Meng; Fu, Gang; Bai, Changan

    2014-11-01

    A design of bionic acoustic metamaterial and acoustic functional devices was proposed by employing the mammalian cochlear as a prototype. First, combined with the experimental data in previous literatures, it is pointed out that the cochlear hair cells and stereocilia cluster are a kind of natural biological acoustic metamaterials with the negative stiffness characteristics. Then, to design the acoustic functional devices conveniently in engineering application, a simplified parametric helical structure was proposed to replace actual irregular cochlea for bionic design, and based on the computational results of such a bionic parametric helical structure, it is suggested that the overall cochlear is a local resonant system with the negative dynamic effective mass characteristics. There are many potential applications in the bandboard energy recovery device, cochlear implant, and acoustic black hole.

  15. Virtual acoustics displays

    NASA Astrophysics Data System (ADS)

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

    1991-03-01

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

  16. Broad-band acoustic hyperbolic metamaterial

    E-print Network

    Shen, Chen; Sui, Ni; Wang, Wenqi; Cummer, Steven A; Jing, Yun

    2015-01-01

    Acoustic metamaterials (AMMs) are engineered materials, made from subwavelength structures, that exhibit useful or unusual constitutive properties. There has been intense research interest in AMMs since its first realization in 2000 by Liu et al. A number of functionalities and applications have been proposed and achieved using AMMs. Hyperbolic metamaterials are one of the most important types of metamaterials due to their extreme anisotropy and numerous possible applications, including negative refraction, backward waves, spatial filtering, and subwavelength imaging. Although the importance of acoustic hyperbolic metamaterials (AHMMs) as a tool for achieving full control of acoustic waves is substantial, the realization of a broad-band and truly hyperbolic AMM has not been reported so far. Here, we demonstrate the design and experimental characterization of a broadband AHMM that operates between 1.0 kHz and 2.5 kHz.

  17. Development of a surface-wave imaging system for geotechnical applications based on distributed acoustic sensing (DAS) and ambient noise interferometry

    NASA Astrophysics Data System (ADS)

    Ajo Franklin, J. B.; Daley, T. M.; Freifeld, B. M.; Tang, D. G.; Zhang, R.; Wagner, A. M.; Dou, S.; Lindsey, N.; Bjella, K.; Pevzner, R.

    2014-12-01

    Distributed fiber-optic sensing methods have been used since the 1980's for continuous monitoring of near-surface soil properties, typically exploiting Raman scattering to measure temperature (DTS) or stimulated Brillouin scattering to measure strain (DSS). Recent advances in high speed measurement of Rayleigh scattering has enabled distributed recording of seismic waves over long sections of fiber; this approach, referred to as distributed acoustic sensing (DAS) has the potential to allow nearly continuous monitoring of near-surface mechanical properties, a crucial target for geotechnical management of infrastructure dependent on soil strength. We present initial results from our effort to build a real-time soil property monitoring system based on DAS; our approach employs seismic interferometry and dispersion analysis of ambient noise generated by infrastructure to provide a continuously updated model of shear modulus. Our preliminary results include an in-depth investigation of DAS fiber response in the context of active sources; this component of our study verifies classical models for the azimuthal response of straight fibers to propagating surface waves. We also explore the "noisescape" of linear infrastructure and show a usable seismic signal band of 8-40 hz at a series of sites, primarily consisting of Rayleigh waves. Finally, we present preliminary results from a DAS monitoring array installed at the Richmond Field Station near a heavily used road and compare interferometric processing of the acquired data to that generated by surface deployment of geophones.

  18. Generation of Sound Bullets with a Nonlinear Acoustic Lens

    E-print Network

    Alessandro Spadoni; Chiara Daraio

    2009-08-31

    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. The lens consists of ordered arrays of granular chains. The amplitude, size and location of the sound bullets can be controlled by varying static pre-compression on the chains. We support our findings with theory, numerical simulations, and corroborate the results experimentally with photoelasticity measurements. Our nonlinear lens makes possible a qualitatively new way of generating high-energy acoustic pulses, enabling, for example, surgical control of acoustic energy.

  19. A new acoustic lens material for large area detectors in photoacoustic breast tomography?

    PubMed Central

    Xia, Wenfeng; Piras, Daniele; van Hespen, Johan C.G.; Steenbergen, Wiendelt; Manohar, Srirang

    2013-01-01

    Objectives We introduce a new acoustic lens material for photoacoustic tomography (PAT) to improve lateral resolution while possessing excellent acoustic acoustic impedance matching with tissue to minimize lens induced image artifacts. Background A large surface area detector due to its high sensitivity is preferable to detect weak signals in photoacoustic mammography. The lateral resolution is then limited by the narrow acceptance angle of such detectors. Acoustic lenses made of acrylic plastic (PMMA) have been used to enlarge the acceptance angle of such detectors and improve lateral resolution. However, such PMMA lenses introduce image artifacts due to internal reflections of ultrasound within the lenses, the result of acoustic impedance mismatch with the coupling medium or tissue. Methods A new lens is proposed based on the 2-component resin Stycast 1090SI. We characterized the acoustic properties of the proposed lens material in comparison with commonly used PMMA, inspecting the speed of sound, acoustic attenuation and density. We fabricated acoustic lenses based on the new material and PMMA, and studied the effect of the acoustic lenses on detector performance comparing finite element (FEM) simulations and measurements of directional sensitivity, pulse-echo response and frequency response. We further investigated the effect of using the acoustic lenses on the image quality of a photoacoustic breast tomography system using k-Wave simulations and experiments. Results Our acoustic characterization shows that Stycast 1090SI has tissue-like acoustic impedance, high speed of sound and low acoustic attenuation. These acoustic properties ensure an excellent acoustic lens material to minimize the acoustic insertion loss. Both acoustic lenses show significant enlargement of detector acceptance angle and lateral resolution improvement from modeling and experiments. However, the image artifacts induced by the presence of an acoustic lens are reduced using the proposed lens compared to PMMA lens, due to the minimization of internal reflections. Conclusions The proposed Stycast 1090SI acoustic lens improves the lateral resolution of photoacoustic tomography systems while not suffering from internal reflection-induced image artifacts compared a lens made of PMMA. PMID:25302146

  20. Photoacoustic imaging of small organic molecule-based photoacoustic probe in subcutaneous tumor using P(VDF-TrFE) acoustic sensor

    NASA Astrophysics Data System (ADS)

    Hirasawa, Takeshi; Okawa, Shinpei; Kamiya, Mako; Urano, Yasuteru; Ishihara, Miya

    2015-03-01

    The P(VDF-TrFE) sensor which had uniform sensitivity in a frequency range of 2.9 - 19.6 MHz was developed for multispectral photoacoustic imaging (MS-PAI). A small organic molecule-based PA probe synthesized by our group had the absorption maximum at 530 nm and was used as a contrast agent. The PA probe was designed to have low quantum yield. Therefore, the PA probe efficiently converted absorbed optical energies to PA signals. The probe was injected in subcutaneous tumor of mice. Then, the subcutaneous tumor was imaged in vivo by using P(VDF-TrFE) sensor. MS-PAI successfully discriminated the probe signals from background signals produced from endogenous optical absorbers such as hemoglobin. The probe detectability of the P(VDF-TrFE) sensor was evaluated and then compared with that of lead zirconium titanate (PZT) sensors. The P(VDF-TrFE) sensor imaged the tumor more clearly than the PZT sensor with central frequency of 20 MHz, especially when the probe was accumulated in the tumor with low concentration. That was because the low-concentrated probe generated PA signals with low frequency. MS-PAI using P(VDF-TrFE) sensor which can detect PA signals with wide range of frequency is able to image various distribution of the probe and is superior to that using PZT sensor which detects PA signals with narrow frequency range.

  1. Perfluorocarbon Nanoparticles for Molecular Imaging and

    E-print Network

    McCarthy, John E.

    to include magnetic resonance (MR) imaging, positron emission tomography (PET), single photon emission magnetic resonance and acoustic imaging techniques. Identification of these molecular markers requires concentrations of cell surface biochemical markers with magnetic resonance imaging (MRI) or single photon

  2. Intrinsically irreversible acoustic heat engines

    SciTech Connect

    Swift, G.W.; Migliori, A.; Hofler, T.; Wheatley, J.C.

    1985-01-01

    The working processes and some basic theory of the irreversible acoustic heat engine are briefly discussed. Three current projects on acoustic heat engines are highlighted. Projects include an acoustic cryocooler, a ''beer cooler'', and a liquid sodium acoustic primer mover. Diagrams of the three heat engines are included.

  3. Acoustic Source Localization Using the Acoustic ENSBox

    E-print Network

    Blumstein, Daniel T.

    -based source lo- calization algorithm. We will demonstrate a system that is easy to set up and that can-acoustic field research. In this work, we demonstrate a real-time wire- less sensor system that implements an AML described in our corresponding paper [1]. Categories and Subject Descriptors C.3 [Special

  4. Acoustic cooling engine

    DOEpatents

    Hofler, Thomas J. (Los Alamos, NM); Wheatley, John C. (Los Alamos, NM); Swift, Gregory W. (Santa Fe, NM); Migliori, Albert (Santa Fe, NM)

    1988-01-01

    An acoustic cooling engine with improved thermal performance and reduced internal losses comprises a compressible fluid contained in a resonant pressure vessel. The fluid has a substantial thermal expansion coefficient and is capable of supporting an acoustic standing wave. A thermodynamic element has first and second ends and is located in the resonant pressure vessel in thermal communication with the fluid. The thermal response of the thermodynamic element to the acoustic standing wave pumps heat from the second end to the first end. The thermodynamic element permits substantial flow of the fluid through the thermodynamic element. An acoustic driver cyclically drives the fluid with an acoustic standing wave. The driver is at a location of maximum acoustic impedance in the resonant pressure vessel and proximate the first end of the thermodynamic element. A hot heat exchanger is adjacent to and in thermal communication with the first end of the thermodynamic element. The hot heat exchanger conducts heat from the first end to portions of the resonant pressure vessel proximate the hot heat exchanger. The hot heat exchanger permits substantial flow of the fluid through the hot heat exchanger. The resonant pressure vessel can include a housing less than one quarter wavelength in length coupled to a reservoir. The housing can include a reduced diameter portion communicating with the reservoir. The frequency of the acoustic driver can be continuously controlled so as to maintain resonance.

  5. Description of an optimized ChIP-seq analysis pipeline dedicated to genome wide identification of E4F1 binding sites in primary and transformed MEFs?

    PubMed Central

    Houls, Thibault; Rodier, Genevive; Le Cam, Laurent; Sardet, Claude; Kirsh, Olivier

    2015-01-01

    This Data in Brief report describes the experimental and bioinformatic procedures that we used to analyze and interpret E4F1 ChIP-seq experiments published in Rodier et al. (2015) [10]. Raw and processed data are available at the GEO DataSet repository under the subseries # GSE57228. E4F1 is a ubiquitously expressed zinc-finger protein of the GLI-Kruppel family that was first identified in the late eighties as a cellular transcription factor targeted by the adenoviral oncoprotein E1A13S (Ad type V) and required for the transcription of adenoviral genes (Raychaudhuri et al., 1987) [8]. It is a multifunctional factor that also acts as an atypical E3 ubiquitin ligase for p53 (Le Cam et al., 2006) [2]. Using KO mouse models we then demonstrated that E4F1 is essential for early embryonic development (Le Cam et al., 2004), for proliferation of mouse embryonic cell (Rodier et al., 2015), for the maintenance of epidermal stem cells (Lacroix et al., 2010) [6], and strikingly, for the survival of cancer cells (Hatchi et al., 2007) [4]; (Rodier et al., 2015) [10]. The latter survival phenotype was p53-independent and suggested that E4F1 was controlling a transcriptional program driving essential functions in cancer cells. To identify this program, we performed E4F1 ChIP-seq analyses in primary Mouse Embryonic Fibroblasts (MEF) and in p53?/?, H-RasV12-transformed MEFs. The program directly controlled by E4F1 was obtained by intersecting the lists of E4F1 genomic targets with the lists of genes differentially expressed in E4F1 KO and E4F1 WT cells (Rodier et al., 2015). We describe hereby how we improved our ChIP-seq analyses workflow by applying prefilters on raw data and by using a combination of two publicly available programs, Cisgenome and QESEQ. PMID:26484288

  6. Identical de novo mutation at the D4F104S1 locus in monozygotic male twins affected by facioscapulohumeral muscular dystrophy (FSHD) with different clinical expression.

    PubMed Central

    Tupler, R; Barbierato, L; Memmi, M; Sewry, C A; De Grandis, D; Maraschio, P; Tiepolo, L; Ferlini, A

    1998-01-01

    Facioscapulohumeral muscular dystrophy (FSHD) is a progressive hereditary neuromuscular disorder, transmitted in an autosomal dominant fashion. Its clinical expression is highly variable, ranging from almost asymptomatic subjects to wheelchair dependent patients. The molecular defect has been linked to chromosome 4q35 markers and has been related to deletions of tandemly repeated sequences located in the subtelomeric region detected by probe p13E-11 (D4F104S1). We describe a pair of monozygotic male twins affected by FSHD, carrying an identical de novo p13E-11 EcoRI fragment of paternal origin and showing great variability in the clinical expression of the disease, one being almost asymptomatic and the other severely affected. Their medical history was the same, with the exception of an anti-rabies vaccination performed at the age of 5 in the more severely affected twin. We hypothesise that the vaccination might have triggered an inflammatory immune reaction contributing to the more severe phenotype. Images PMID:9733041

  7. Acoustic well cleaner

    DOEpatents

    Maki, Jr., Voldi E. (11904 Bell Ave., Austin, TX 78759-2415); Sharma, Mukul M. (Dept. of Petroleum Engr. Univ. of Texas, Austin, TX 78712)

    1997-01-21

    A method and apparatus are disclosed for cleaning the wellbore and the near wellbore region. A sonde is provided which is adapted to be lowered into a borehole and which includes a plurality of acoustic transducers arranged around the sonde. Electrical power provided by a cable is converted to acoustic energy. The high intensity acoustic energy directed to the borehole wall and into the near wellbore region, redissolves or resuspends the material which is reducing the permeability of the formation and/or restricting flow in the wellbore.

  8. Acoustical heat pumping engine

    DOEpatents

    Wheatley, J.C.; Swift, G.W.; Migliori, A.

    1983-08-16

    The disclosure is directed to an acoustical heat pumping engine without moving seals. A tubular housing holds a compressible fluid capable of supporting an acoustical standing wave. An acoustical driver is disposed at one end of the housing and the other end is capped. A second thermodynamic medium is disposed in the housing near to but spaced from the capped end. Heat is pumped along the second thermodynamic medium toward the capped end as a consequence both of the pressure oscillation due to the driver and imperfect thermal contact between the fluid and the second thermodynamic medium. 2 figs.

  9. Tunable acoustic metamaterials

    NASA Astrophysics Data System (ADS)

    Babaee, Sahab; Viard, Nicolas; Fang, Nicholas; Bertoldi, Katia

    2015-03-01

    We report a new class of active and switchable acoustic metamaterials composed of three-dimensional stretchable chiral helices arranged on a two-dimensional square lattice. We investigate the propagation of sounds through the proposed structure both numerically and experimentally and find that the deformation of the helices can be exploited as a novel and effective approach to control the propagation of acoustic waves. The proposed concept expands the ability of existing acoustic metamaterials since we demonstrate that the deformation can be exploited to turn on or off the band gap, opening avenues for the design of adaptive noise-cancelling devices.

  10. Acoustical heat pumping engine

    DOEpatents

    Wheatley, John C. (Los Alamos, NM); Swift, Gregory W. (Los Alamos, NM); Migliori, Albert (Santa Fe, NM)

    1983-08-16

    The disclosure is directed to an acoustical heat pumping engine without moving seals. A tubular housing holds a compressible fluid capable of supporting an acoustical standing wave. An acoustical driver is disposed at one end of the housing and the other end is capped. A second thermodynamic medium is disposed in the housing near to but spaced from the capped end. Heat is pumped along the second thermodynamic medium toward the capped end as a consequence both of the pressure oscillation due to the driver and imperfect thermal contact between the fluid and the second thermodynamic medium.

  11. Order-disorder phase transition in the antiperovskite-type structure of synthetic kogarkoite, Na3SO4F

    NASA Astrophysics Data System (ADS)

    Avdontceva, Margarita S.; Zolotarev, Andrey A.; Krivovichev, Sergey V.

    2015-11-01

    High-temperature phase transition of synthetic kogarkoite, Na3SO4F, has been studied by high-temperature X-ray powder and single-crystal diffraction. The temperature of the phase transition can be estimated as 112.512.5 C. The low-temperature phase, ?-Na3SO4F, at 293 K, is monoclinic, P21/m, a=18.065(3), b=6.958(1), c=11.446(1) , ?=107.711(1), Z=12. The structure contains thirteen symmetrically independent Na sites with coordination numbers varying from 6 to 8, and six independent S sites. The high-temperature ?-phase at 423 K is rhombohedral, R-3m, a=6.94(1), c=24.58(4) , Z=9. The crystal structure of both polymorphs of Na3SO4F can be described as a 9R antiperovskite polytype based upon triplets of face-sharing [FNa6] octahedra linked into a three-dimensional framework by sharing corners. In the ?-modification, the SO4 tetrahedra are completely ordered and located in the framework cavities. In the ?-modification, there are only two symmetrically independent Na atoms in the structure. The main difference between the structures of the ?- and ?-phases is the degree of ordering of the SO4 tetrahedra: in the ?-modification, they are completely ordered, whereas, in the ?-modification, the complete disorder is observed, which is manifested in a number of low-occupied O sites around fully occupied S sites. The phase transition is therefore has an order-disorder character and is associated with the decrease of structural complexity measured as an information content per unit cell [577.528 bits for the low- (?) and 154.830 bits for the high- (?) temperature modifications].

  12. Improving limited-view photoacoustic tomography with an acoustic reflector

    PubMed Central

    Huang, Bin; Xia, Jun; Maslov, Konstantin; Wang, Lihong V.

    2013-01-01

    Abstract. The versatility and real-time imaging capability of commercial linear array transducers make them widely used in clinical ultrasound and photoacoustic imaging. However, they often suffer from limited detection view. For instance, acoustic waves traveling at a grazing angle to the transducer surface are difficult to detect. In this letter, we propose a simple and easy approach to ameliorate this problem by using a 45-deg acoustic reflector. The reflector forms a virtual array that is perpendicular to the physical array, thereby doubling the detection coverage. The improvement in image quality in photoacoustic tomography was demonstrated through a hair phantom, a leaf skeleton phantom, and an ex vivo mouse ear experiment.

  13. Single-ion 4f element magnetism: an ab-initio look at Ln(COT)2(.).

    PubMed

    Gendron, Frdric; Pritchard, Benjamin; Bolvin, Hlne; Autschbach, Jochen

    2015-11-18

    The electron densities associated with the Ln 4f shell, and spin and orbital magnetizations ('magnetic moment densities'), are investigated for the Ln(COT)2(-) series. The densities are obtained from ab-initio calculations including spin-orbit coupling. For Ln = Ce, Pr the magnetizations are also derived from crystal field models and shown to agree with the ab-initio results. Analysis of magnetizations from ab-initio calculations may be useful in assisting research on single molecule magnets. PMID:26510902

  14. Prediction of Acoustic Noise in Switched Reluctance Motor Drives

    SciTech Connect

    Lin, CJ; Fahimi, B

    2014-03-01

    Prediction of acoustic noise distribution generated by electric machines has become an integral part of design and control in noise sensitive applications. This paper presents a fast and precise acoustic noise imaging technique for switched reluctance machines (SRMs). This method is based on distribution of radial vibration in the stator frame of the SRM. Radial vibration of the stator frame, at a network of probing points, is computed using input phase current and phase voltage waveforms. Sequentially, the acceleration of the probing network will be expanded to predict full acceleration on the stator frame surface, using which acoustic noise emission caused by the stator can be calculated using the boundary element method.

  15. Acoustically induced transparency using Fano resonant periodic arrays

    NASA Astrophysics Data System (ADS)

    Amin, M.; Elayouch, A.; Farhat, M.; Addouche, M.; Khelif, A.; Ba?c?, H.

    2015-10-01

    A three-dimensional acoustic device, which supports Fano resonance and induced transparency in its response to an incident sound wave, is designed and fabricated. These effects are generated from the destructive interference of closely coupled one broad- and one narrow-band acoustic modes. The proposed design ensures excitation and interference of two spectrally close modes by locating a small pipe inside a wider and longer one. Indeed, numerical simulations and experiments demonstrate that this simple-to-fabricate structure can be used to generate Fano resonance as well as acoustically induced transparency with promising applications in sensing, cloaking, and imaging.

  16. Vapor pressures of mixtures of CFC-114 with the potential replacement coolants C{sub 4}F{sub 10} and c-C{sub 4}F{sub 8}

    SciTech Connect

    Trowbridge, L.D.; Otey, M.G.

    1994-09-01

    The U.S. Enrichment Corporation`s production of isotopically enriched uranium depends solely on two plants which utilize the gaseous diffusion process. This process uses large quantities of CFC-114 as an evaporative coolant. CFC-114, however, will be phased out of production at the end of 1995 due to its potential to deplete stratospheric ozone. A search has been underway for substitutes for a number of years. The initial search (1988-89) for an ozone-friendly, commercially available, chemically compatible substitute yielded two candidates, FC-c318 (c-C{sub 4}F{sub 8}) and FC-3110 (C{sub 4}F{sub 10}). The intended mode of replacing coolant was to stage the new coolant into independent subsystems of the plants, so that some systems would continue to operate on CFC-114, and an increasing number would operate on the new coolant. During that changeover process, the possibility of coolant mixing arises in variety of scenarios. This work was intended to generate sufficient experimental information to be able to predict the vapor pressure of coolant mixtures over the range of operating conditions likely to be found in the diffusion plants. Specifically, vapor pressures were measured over the temperature range 322 to 355 K (120{degrees}F to 180{degrees}F) and over the full range of mole fractions for binary mixtures of CFC-114 with FC-3110, and of CFC-114 with FC-c318.

  17. Short-core acoustic resonant bar test and x-ray CT imaging on sandstone samples during super-critical CO2 flooding and dissolution

    NASA Astrophysics Data System (ADS)

    Nakagawa, S.; Kneafsey, T. J.; Daley, T. M.; Freifeld, B. M.

    2010-12-01

    Geological sequestration of CO2 requires accurate monitoring of the spatial distribution and pore-level saturation of super-critical (sc-) CO2 for both optimizing reservoir performance and satisfying regulatory requirements. Fortunately, thanks to the high compliance of sc-CO2 compared to brine under in-situ temperatures and pressures, injection of sc-CO2 into initially brine-saturated rock will lead to significant reductions in seismic velocity and increased attenuation of seismic waves. Because of the frequency-dependent nature of this relationship, its determination requires testing at low frequencies (10 Hz-10 kHz) that are not usually employed in the laboratory. In this paper, we present the changes in seismic wave velocities and attenuation in sandstone cores during sc-CO2 core flooding and during subsequent brine re-injection and CO2 removal via convection and dissolution. The experiments were conducted at frequencies near 1 kHz using a variation of the acoustic resonant bar technique, called the Split Hopkinson Resonant Bar (SHRB) method, which allows measurements under elevated temperatures and pressures (up to 120C, 35 MPa), using a short (several cm long) core. Concurrent x-ray CT scanning reveals sc-CO2 saturation and distribution within the cores. The injection experiments revealed different CO2 patch size distributions within the cores between the injection phase and the convection/dissolution phase of the tests. The difference was reflected particularly in the P-wave velocities and attenuation. Also, compared to seismic responses, which were separately measured during a gas CO2 injection/drainage test, the seismic responses from the sc-CO2 test showed measurable changes over a wider range of brine saturation. Considering the proximity of the frequency band employed by our measurement to the field seismic measurements, this result implies that seismic monitoring of sc-CO2, if constrained by laboratory data and interpreted using a proper petrophysical model, can be conducted with greater accuracy for determining the sc-CO2 saturation and distribution within reservoir rock, than typically predicted by the Gassmann model and/or by a natural gas reservoir analogue.

  18. Space, time and acoustics

    E-print Network

    Thompson, Philip R. Z. (Philip Reed Zane)

    1988-01-01

    This thesis describes the development of new concepts in acoustical analysis from their inception to implementation as a computer design tool. Research is focused on a computer program which aids the designer to visually ...

  19. Acoustics lecturing in Mexico

    NASA Astrophysics Data System (ADS)

    Beristain, Sergio

    2002-11-01

    Some thirty years ago acoustics lecturing started in Mexico at the National Polytechnic Institute in Mexico City, as part of the Bachelor of Science degree in Communications and Electronics Engineering curricula, including the widest program on this field in the whole country. This program has been producing acoustics specialists ever since. Nowadays many universities and superior education institutions around the country are teaching students at the B.Sc. level and postgraduate level many topics related to acoustics, such as Architectural Acoustics, Seismology, Mechanical Vibrations, Noise Control, Audio, Audiology, Music, etc. Also many institutions have started research programs in related fields, with participation of medical doctors, psychologists, musicians, engineers, etc. Details will be given on particular topics and development.

  20. Compact acoustic refrigerator

    SciTech Connect

    Bennett, G.A.

    1991-12-31

    This invention is comprised of a compact acoustic refrigeration system that actively cools components, e.g., electrical circuits, in a borehole environment. An acoustic engine includes first thermodynamic elements for generating a standing acoustic wave in a selected medium. An acoustic refrigerator includes second thermodynamic elements located in the standing wave for generating a relatively cold temperature at a first end of the second thermodynamic elements and a relatively hot temperature at a second end of the second thermodynamic elements. A resonator volume cooperates with the first and second thermodynamic elements to support the standing wave. To accommodate the high heat fluxes required for heat transfer to/from the first and second thermodynamic elements, first heat pipes transfer heat from the heat load to the second thermodynamic elements and second heat pipes transfer heat from first and second thermodynamic elements to the borehole environment.

  1. Compact acoustic refrigerator

    DOEpatents

    Bennett, G.A.

    1992-11-24

    A compact acoustic refrigeration system actively cools components, e.g., electrical circuits, in a borehole environment. An acoustic engine includes first thermodynamic elements for generating a standing acoustic wave in a selected medium. An acoustic refrigerator includes second thermodynamic elements located in the standing wave for generating a relatively cold temperature at a first end of the second thermodynamic elements and a relatively hot temperature at a second end of the second thermodynamic elements. A resonator volume cooperates with the first and second thermodynamic elements to support the standing wave. To accommodate the high heat fluxes required for heat transfer to/from the first and second thermodynamic elements, first heat pipes transfer heat from the heat load to the second thermodynamic elements and second heat pipes transfer heat from first and second thermodynamic elements to the borehole environment. 18 figs.

  2. An acoustic invisible gateway

    E-print Network

    Zhu, Yi-Fan; Liang, Bin; Kan, Wei-Wei; Yang, Jun; Cheng, Jian-Chun

    2015-01-01

    The recently-emerged concept of "invisible gateway" with the extraordinary capability to block the waves but allow the passage of other entities has attracted great attentions due to the general interests in illusion devices. However, the possibility to realize such a fascinating phenomenon for acoustic waves has not yet been explored, which should be of paramount significance for acoustical applications but would necessarily involve experimental difficulty. Here we design and experimentally demonstrate an acoustic invisible gateway (AIG) capable of concealing a channel under the detection of sound. Instead of "restoring" a whole block of background medium by using transformation acoustics that inevitably requires complementary or restoring media with extreme parameters, we propose an inherently distinct methodology that only aims at engineering the surface impedance at the "gate" to mimic a rigid "wall" and can be conveniently implemented by decorating meta-structures behind the channel. Such a simple yet ef...

  3. Compact acoustic refrigerator

    DOEpatents

    Bennett, Gloria A. (Los Alamos, NM)

    1992-01-01

    A compact acoustic refrigeration system actively cools components, e.g., electrical circuits (22), in a borehole environment. An acoustic engine (12, 14) includes first thermodynamic elements (12) for generating a standing acoustic wave in a selected medium. An acoustic refrigerator (16, 26, 28) includes second thermodynamic elements (16) located in the standing wave for generating a relatively cold temperature at a first end of the second thermodynamic elements (16) and a relatively hot temperature at a second end of the second thermodynamic elements (16). A resonator volume (18) cooperates with the first and second thermodynamic elements (12, 16) to support the standing wave. To accommodate the high heat fluxes required for heat transfer to/from the first and second thermodynamic elements (12, 16), first heat pipes (24, 26) transfer heat from the heat load (22) to the second thermodynamic elements (16) and second heat pipes (28, 32) transfer heat from first and second thermodynamic elements (12, 16) to the borehole environment.

  4. Directional acoustic underwater thruster.

    PubMed

    Wang, Ziyu; Qiu, Xiaotun; Zhu, Jie; Oiler, Jon; Chen, Shih-Jui; Shi, Jing; Kim, Eun; Yu, Hongyu

    2011-06-01

    This study describes a tested prototype for a controllable directional underwater thruster with no moving parts. During operation, a high-intensity acoustic wave creates directional water jets and the device moves itself in the opposite direction. When the underwater thruster moves along a non-vertical angle, it can produce straight backward thrust of 2.3 mN and lateral thrust of 0.6 mN in parallel with the device surface, with a total thrust-to-weight ratio of 2:1. To enhance the acoustic streaming effect, a self-focusing acoustic transducer (SFAT) with air reflectors is used to focus the acoustic wave. PMID:21693390

  5. Non-linear acoustic concealed weapons detection (CWD)

    NASA Astrophysics Data System (ADS)

    Heyman, Joseph S.; Achanta, Anjani; Hinders, Mark; Rudd, Kevin; Costianes, Peter J.

    2005-05-01

    In this paper we describe an acoustic weapons detection concept that is based on ultrasonics and nonlinear acoustics. An ultrasonic projector is used to create an acoustic field at the site of inspection. The field is composed of multiple ultrasonic waves interacting at the interrogation site. The ultrasonic field creates acoustic interactions at that site which are used as the primary probe. The acoustic field is tailored to excite the target in an optimum fashion for weapons detection. In this presentation, we present aspects of this approach highlighting its ability to confine the interrogation field, create a narrow-band probing field, and the ability to scan that acoustic field to image objects. Ultrasonic propagation parameters that influence the field will be presented as will data of field characteristics. An image obtained with this system will be shown, demonstrating its capability to achieve high resolution. Effects of cloth over a weapon are shown to alter the image, yet not hide the weapon. Luna will report on its most recent findings as to the nature of this detection technology and its ability to generate information important to CWD.

  6. Determination of Absolute Protein Content of Hepatic CYP4F Enzymes in Human Liver Microsomes Using LC/MS/MS Methodology and Comparison with Immunoquantification and Enzyme Activity

    E-print Network

    Michaels, Scott

    2013-08-31

    The purpose of the work presented herein was to determine the absolute protein content of multiple cytochrome P450 (CYP) enzymes in individual donor human liver microsome (HLM) samples. The CYP4F subfamily of enzymes have recently been identified...

  7. Negative Ions in a Dual-Frequency Capacitive Plasma in Ar/C_4F_8/O_2.

    NASA Astrophysics Data System (ADS)

    Booth, Jean-Paul; Curley, Garrett; Bulcourt, Nicolas; Dine, Sebastien

    2004-09-01

    Dual-frequency capacitive plasmas in Ar/C_4F_8/O2 gas mixtures are widely used for etching dielectric materials in integrated circuit manufacture. C_4F8 is reported to be a highly electronegative gas [1] and therefore one would expect that negative ions could play an important role in this type of plasma. The presence of negative ions will modify the positive ion velocity at the sheath edge and therefore the positive ion flux arriving at a surface. We have attempted to directly measure the negative fluorine ion F^- density using broadband UV absorption spectroscopy, setting an upper limit on their density of 5x10^11cm-3. These measurements were complimented by measurements of the positive ion flux and the electron density. In conjunction with analytical models, these methods provide another avenue to determine the negative ion fraction. We acknowledge financial support from the Lam Foundation. [1] Kono et al, Jpn. J. Appl. Phys. (39) 2000, 1365-1368

  8. Photocatalytic activity of NH4F-doped TiO2 modified by noble metal nanoparticle deposition.

    PubMed

    Dozzi, Maria Vittoria; Saccomanni, Alessia; Altomare, Marco; Selli, Elena

    2013-04-01

    The effect of noble metal (Pt and Au) nanoparticle photodeposition on a series of NH4F-doped TiO2 photocatalysts calcined at 700 C was investigated both in a thermodynamically down-hill reaction, i.e. the degradation of formic acid in aqueous suspension, and in an up-hill reaction, i.e. hydrogen production from methanol-water vapour mixtures. All photocatalysts were characterized by BET, XRD, UV-vis absorption and HRTEM analysis. Intriguing synergistic effects of simultaneous bulk and surface TiO2 modification were evidenced in both photocatalytic reactions, which can be interpreted in relation to the structural features of the materials. On one hand NH4F doping guarantees that the most active TiO2 anatase phase is stabilised up to high calcination temperature, ensuring high crystallinity and good photoinduced charge carriers production, on the other hand noble metal nanoparticles contribute in increasing the separation of photoproduced charge carriers, resulting in enhanced photocatalytic performances of the surface- and bulk-modified photocatalyst systems. PMID:22930393

  9. Design and synthesis of thiazolo[5,4-f]quinazolines as DYRK1A inhibitors, part II.

    PubMed

    Foucourt, Alicia; Hdou, Damien; Dubouilh-Benard, Carole; Girard, Anglique; Taverne, Thierry; Casagrande, Anne-Sophie; Dsir, Laurent; Leblond, Bertrand; Besson, Thierry

    2014-01-01

    The convenient synthesis of a focused library (forty molecules) of novel 6,6,5-tricyclic thiazolo[5,4-f]quinazolines was realized mainly under microwave irradiation. A novel 6-aminobenzo[d]thiazole-2,7-dicarbonitrile (1) was used as a versatile molecular platform for the synthesis of various derivatives. Kinase inhibition, of the obtained final compounds, was evaluated on a panel of two kinases (DYRK1A/1B) together with some known reference DYRK1A and DYRK1B inhibitors (harmine, TG003, NCGC-00189310 and leucettine L41). Compound IC50 values were obtained and compared. Five of the novel thiazolo[5,4-f]quinazoline derivatives prepared, EHT 5372 (8c), EHT 6840 (8h), EHT 1610 (8i), EHT 9851 (8k) and EHT 3356 (9b) displayed single-digit nanomolar or subnanomolar IC50 values and are among the most potent DYRK1A/1B inhibitors disclosed to date. DYRK1A/1B kinases are known to be involved in the regulation of various molecular pathways associated with oncology, neurodegenerative diseases (such as Alzheimer disease, AD, or other tauopathies), genetic diseases (such as Down Syndrome, DS), as well as diseases involved in abnormal pre-mRNA splicing. The compounds described in this communication constitute a highly potent set of novel molecular probes to evaluate the biology/pharmacology of DYR1A/1B in such diseases. PMID:25264830

  10. Quantum Acoustics with Surface Acoustic Waves

    E-print Network

    Thomas Aref; Per Delsing; Maria K. Ekstrm; Anton Frisk Kockum; Martin V. Gustafsson; Gran Johansson; Peter Leek; Einar Magnusson; Riccardo Manenti

    2015-06-04

    It has recently been demonstrated that surface acoustic waves (SAWs) can interact with superconducting qubits at the quantum level. SAW resonators in the GHz frequency range have also been found to have low loss at temperatures compatible with superconducting quantum circuits. These advances open up new possibilities to use the phonon degree of freedom to carry quantum information. In this paper, we give a description of the basic SAW components needed to develop quantum circuits, where propagating or localized SAW-phonons are used both to study basic physics and to manipulate quantum information. Using phonons instead of photons offers new possibilities which make these quantum acoustic circuits very interesting. We discuss general considerations for SAW experiments at the quantum level and describe experiments both with SAW resonators and with interaction between SAWs and a qubit. We also discuss several potential future developments.

  11. Volumetric Acoustic Vector Intensity Probe

    NASA Technical Reports Server (NTRS)

    Klos, Jacob

    2006-01-01

    A new measurement tool capable of imaging the acoustic intensity vector throughout a large volume is discussed. This tool consists of an array of fifty microphones that form a spherical surface of radius 0.2m. A simultaneous measurement of the pressure field across all the microphones provides time-domain near-field holograms. Near-field acoustical holography is used to convert the measured pressure into a volumetric vector intensity field as a function of frequency on a grid of points ranging from the center of the spherical surface to a radius of 0.4m. The volumetric intensity is displayed on three-dimensional plots that are used to locate noise sources outside the volume. There is no restriction on the type of noise source that can be studied. The sphere is mobile and can be moved from location to location to hunt for unidentified noise sources. An experiment inside a Boeing 757 aircraft in flight successfully tested the ability of the array to locate low-noise-excited sources on the fuselage. Reference transducers located on suspected noise source locations can also be used to increase the ability of this device to separate and identify multiple noise sources at a given frequency by using the theory of partial field decomposition. The frequency range of operation is 0 to 1400Hz. This device is ideal for the study of noise sources in commercial and military transportation vehicles in air, on land and underwater.

  12. Structure, stability, and photoluminescence in the anti-perovskites Na3W1-xMoxO4F (0?x?1)

    NASA Astrophysics Data System (ADS)

    Sullivan, Eirin; Avdeev, Maxim; Blom, Douglas A.; Gahrs, Casey J.; Green, Robert L.; Hamaker, Christopher G.; Vogt, Thomas

    2015-10-01

    Single-phase ordered oxyfluorides Na3WO4F, Na3MoO4F and their mixed members Na3W1-xMoxO4F can be prepared via facile solid state reaction of Na2MO42H2O (M=W, Mo) and NaF. Phases produced from incongruent melts are metastable, but lower temperatures allow for a facile one-step synthesis. In polycrystalline samples of Na3W1-xMoxO4F, the presence of Mo stabilizes the structure against decomposition to spinel phases. Photoluminescence studies show that upon excitation with ?=254 nm and ?=365 nm, Na3WO4F and Na3MoO4F exhibit broad emission maxima centered around 485 nm. These materials constitute new members of the family of self-activating ordered oxyfluoride phosphors with anti-perovskite structures which are amenable to doping with emitters such as Eu3+.

  13. Silver-coated LiVPO4F composite with improved electrochemical performance as cathode material for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Yang, Bo; Yang, Lin

    2015-12-01

    Nano-structured LiVPO4F/Ag composite cathode material has been successfully synthesized via a sol-gel route. The structural and physical properties, as well as the electrochemical performance of the material are compared with those of the pristine LiVPO4F. X-ray diffraction (XRD) and scanning electron microscopy (SEM) reveal that Ag particles are uniformly dispersed on the surface of LiVPO4F without destroying the crystal structure of the bulk material. An analysis of the electrochemical measurements show that the Ag-modified LiVPO4F material exhibits high discharge capacity, good cycle performance (108.5 mAh g-1 after 50th cycles at 0.1 C, 93% of initial discharge capacity) and excellent rate behavior (81.8 mAh g-1 for initial discharge capacity at 5 C). The electrochemical impedance spectroscopy (EIS) results reveal that the adding of Ag decreases the charge-transfer resistance (Rct) of LiVPO4F cathode. This study demonstrates that Ag-coating is a promising way to improve the electrochemical performance of the pristine LiVPO4F for lithium-ion batteries cathode material.

  14. Imaging.

    PubMed

    Wilkinson, R

    1986-12-01

    Imaging of the musculoskeletal system includes many modalities and is an area that is changing rapidly. Selection of the most accurate techniques and avoidance of duplication are vital to both good patient care and cost containment. PMID:3466135

  15. Measuring acoustic habitats

    PubMed Central

    Merchant, Nathan D; Fristrup, Kurt M; Johnson, Mark P; Tyack, Peter L; Witt, Matthew J; Blondel, Philippe; Parks, Susan E

    2015-01-01

    1. Many organisms depend on sound for communication, predator/prey detection and navigation. The acoustic environment can therefore play an important role in ecosystem dynamics and evolution. A growing number of studies are documenting acoustic habitats and their influences on animal development, behaviour, physiology and spatial ecology, which has led to increasing demand for passive acoustic monitoring (PAM) expertise in the life sciences. However, as yet, there has been no synthesis of data processing methods for acoustic habitat monitoring, which presents an unnecessary obstacle to would-be PAM analysts. 2. Here, we review the signal processing techniques needed to produce calibrated measurements of terrestrial and aquatic acoustic habitats. We include a supplemental tutorial and template computer codes in matlab and r, which give detailed guidance on how to produce calibrated spectrograms and statistical analyses of sound levels. Key metrics and terminology for the characterisation of biotic, abiotic and anthropogenic sound are covered, and their application to relevant monitoring scenarios is illustrated through example data sets. To inform study design and hardware selection, we also include an up-to-date overview of terrestrial and aquatic PAM instruments. 3. Monitoring of acoustic habitats at large spatiotemporal scales is becoming possible through recent advances in PAM technology. This will enhance our understanding of the role of sound in the spatial ecology of acoustically sensitive species and inform spatial planning to mitigate the rising influence of anthropogenic noise in these ecosystems. As we demonstrate in this work, progress in these areas will depend upon the application of consistent and appropriate PAM methodologies. PMID:25954500

  16. Prospecting Lighting Applications with Ligand Field Tools and Density Functional Theory: A First-Principles Account of the 4f(7)-4f(6)5d(1) Luminescence of CsMgBr3:Eu(2.).

    PubMed

    Ramanantoanina, Harry; Cimpoesu, Fanica; Gttel, Christian; Sahnoun, Mohammed; Herden, Benjamin; Suta, Markus; Wickleder, Claudia; Urland, Werner; Daul, Claude

    2015-09-01

    The most efficient way to provide domestic lighting nowadays is by light-emitting diodes (LEDs) technology combined with phosphors shifting the blue and UV emission toward a desirable sunlight spectrum. A route in the quest for warm-white light goes toward the discovery and tuning of the lanthanide-based phosphors, a difficult task, in experimental and technical respects. A proper theoretical approach, which is also complicated at the conceptual level and in computing efforts, is however a profitable complement, offering valuable structure-property rationale as a guideline in the search of the best materials. The Eu(2+)-based systems are the prototypes for ideal phosphors, exhibiting a wide range of visible light emission. Using the ligand field concepts in conjunction with density functional theory (DFT), conducted in nonroutine manner, we develop a nonempirical procedure to investigate the 4f(7)-4f(6)5d(1) luminescence of Eu(2+) in the environment of arbitrary ligands, applied here on the CsMgBr3:Eu(2+)-doped material. Providing a salient methodology for the extraction of the relevant ligand field and related parameters from DFT calculations and encompassing the bottleneck of handling large matrices in a model Hamiltonian based on the whole set of 33?462 states, we obtained an excellent match with the experimental spectrum, from first-principles, without any fit or adjustment. This proves that the ligand field density functional theory methodology can be used in the assessment of new materials and rational property design. PMID:26270436

  17. Step-by-step assembly of 4d-4f-3d complex based on heptamolybdate anion

    SciTech Connect

    Wu, Shuting; Deng, Binbin; Jiang, Xiuling; Li, Ronghua; Guo, Jiangbin; Lai, Fulong; Huang, Xihe; Huang, Changcang

    2012-12-15

    Four new complexes, (NH{sub 4}){sub 11.9}[Ln{sub 4.7}(MoO{sub 4})(H{sub 2}O){sub 23}(Mo{sub 7}O{sub 24}){sub 4}]{center_dot}xH{sub 2}O (Ln=Pr, x=34 (1); Ln=Nd, x=19 (2)), [NH{sub 4}]{sub 28}[Ce{sub 8}(MoO{sub 4}){sub 2}(H{sub 2}O){sub 31}(Mo{sub 7}O{sub 24}){sub 8}]{center_dot}74H{sub 2}O (3), and (NH{sub 4}){sub 26}[CoPr{sub 8}(MoO{sub 4}){sub 2}(H{sub 2}O){sub 33}(Mo{sub 7}O{sub 24}){sub 8}]{center_dot}54H{sub 2}O (4) have been synthesized and characterized by single-crystal and powder X-ray diffraction, CHN elemental analyses TGA analyses, IR and UV-Vis spectroscopy. Complex 1-3 are 0D compounds constructed by the connection between Ln{sup III} ions and [Mo{sub 7}O{sub 24}]{sup 6-} unit. In complex 4, the existence of Co{sup II} connects the polyanion clusters into 1D chain. The introduction of 3d metal (cobalt cation) and 4f metal (Ln=Pr{sup III}, Nd{sup III}, Ce{sup III}) encourages the coordination capability for [Mo{sub 7}O{sub 24}]{sup 6-} unit, which shows interesting coordination modes. The [Mo{sub 7}O{sub 24}]{sup 6-} unit in 1-4 shows three new coordination modes, connecting up to four metal cations. Complexes 1-4 show antiferromagnetic behavior via variable temperature magnetic study. The photoluminescence spectrum indicates the photoluminescence property for 4. - Graphical abstract: Heptamolybdate anion shows extraordinary coordination geometry in the presence of both lanthanide cation (Pr{sup III}) and transitional metal cation (Co{sup II}), which give rise to a new 4d-4f-3d complex. Black-Small-Square Highlights: Black-Right-Pointing-Pointer A new 4d-4f-3d complex that containing 1D chain was obtained and discussed. Black-Right-Pointing-Pointer New coordination geometry with higher coordination number of heptamolybdate. Black-Right-Pointing-Pointer Series of heptamolybdate contained complexes were synthesized and characterized. Black-Right-Pointing-Pointer Complexes mentioned above show antiferromagnetic behavior.

  18. Bayesian acoustic prediction assimilating oceanographic and acoustically inverted data

    E-print Network

    Jesus, Srgio M.

    to the environmental model at hand. Here, acoustic prediction is formulated as a Bayesian estimation problem, in which of environmental quantities, solv- ing an acoustic modeling forward problem. With the purpose of estimating acoustic models have to be fed with simplified environmental descriptions, due to computational issues

  19. Autonomous adaptive acoustic relay positioning

    E-print Network

    Cheung, Mei Yi, S.M. Massachusetts Institute of Technology

    2013-01-01

    We consider the problem of maximizing underwater acoustic data transmission by adaptively positioning an autonomous mobile relay so as to learn and exploit spatial variations in channel performance. The acoustic channel ...

  20. Syntheses, crystal structures and properties of series of 4d-4f ln(III)-Ag(I) heterometallic coordination polymers

    NASA Astrophysics Data System (ADS)

    Ran, Xing-Rui; Wang, Ning; Xie, Wei-Ping; Xiong, Yan-Ju; Cheng, Qian; Long, Yi; Yue, Shan-Tang; Liu, Ying-Liang

    2015-05-01

    By control of the experimental parameters such as ligands, pH value and reacting temperature, series of three-dimensional (3D) 4d-4f Ln(III)-Ag(I) porous coordination polymers (PCPs) with interesting chain-layer construction, namely, {[LnIIIAgI(na)(ina)(ox)]2(H2O)}n [Ln=Sm(1), Eu(2), Gd(3), Tb(4), Dy(5), Ho(6), Y(7), Yb(8)], have been successfully synthesized under hydrothermal conditions and structurally characterized. All the complexes are characterized by elemental analyses, FT-IR spectroscopy, Powder X-ray diffraction (PXRD) and thermogravimetric analyses (TGA). Furthermore, the luminescence properties of compounds 2 and 4 and the magsnetic properties of complexes 3 and 5 were also investigated in detail.

  1. Superspace description of wagnerite-group minerals (Mg,Fe,Mn)2(PO4)(F,OH)

    PubMed Central

    Lazic, Biljana; Armbruster, Thomas; Chopin, Christian; Grew, Edward S.; Baronnet, Alain; Palatinus, Lukas

    2014-01-01

    Reinvestigation of more than 40 samples of minerals belonging to the wagnerite group (Mg, Fe, Mn)2(PO4)(F,OH) from diverse geological environments worldwide, using single-crystal X-ray diffraction analysis, showed that most crystals have incommensurate structures and, as such, are not adequately described with known polytype models (2b), (3b), (5b), (7b) and (9b). Therefore, we present here a unified superspace model for the structural description of periodically and aperiodically modulated wagnerite with the (3+1)-dimensional superspace group C2/c(0?0)s0 based on the average triplite structure with cell parameters a ? 12.8, b ? 6.4, c ? 9.6?, ? ? 117 and the modulation vectors q = ? b*. The superspace approach provides a way of simple modelling of the positional and occupational modulation of Mg/Fe and F/OH in wagnerite. This allows direct comparison of crystal properties. PMID:24675594

  2. Metastable level properties of the excited configuration $4p^{6}4d^{8}4f$

    E-print Network

    Karpukien?, R; Kisielius, R

    2015-01-01

    Metastable levels in rhodium-like ions with the ground configuration $4p^{6}4d^{9}$ and the excited configurations $4p^{6}4d^{8}4f$ and $4p^{5}4d^{10}$ are investigated. The {\\sl ab initio} calculations of the level energies, radiative multipole transition probabilities are performed in a quasirelativistic Hartree-Fock approximation employing an extensive configuration interaction based on quasirelativistic transformed radial orbitals. A systematic trends in behavior of calculated radiative lifetimes of the metastable levels are studied for the ions from $Z=60$ to $Z=92$. The significance of the radiative transitions of higher multipole order ($M2$ and $E3$) for the calculated radiative lifetimes is demonstrated and discussed.

  3. Temporal and spatial regulation of translation in the mammalian oocyte via the mTOReIF4F pathway

    PubMed Central

    Susor, Andrej; Jansova, Denisa; Cerna, Renata; Danylevska, Anna; Anger, Martin; Toralova, Tereza; Malik, Radek; Supolikova, Jaroslava; Cook, Matthew S.; Oh, Jeong Su; Kubelka, Michal

    2015-01-01

    The fully grown mammalian oocyte is transcriptionally quiescent and utilizes only transcripts synthesized and stored during early development. However, we find that an abundant RNA population is retained in the oocyte nucleus and contains specific mRNAs important for meiotic progression. Here we show that during the first meiotic division, shortly after nuclear envelope breakdown, translational hotspots develop in the chromosomal area and in a region that was previously surrounded the nucleus. These distinct translational hotspots are separated by endoplasmic reticulum and Lamin, and disappear following polar body extrusion. Chromosomal translational hotspots are controlled by the activity of the mTOReIF4F pathway. Here we reveal a mechanism thatfollowing the resumption of meiosiscontrols the temporal and spatial translation of a specific set of transcripts required for normal spindle assembly, chromosome alignment and segregation. PMID:25629602

  4. Tailoring the coercivity in ferromagnetic ZnO thin films by 3d and 4f elements codoping

    SciTech Connect

    Lee, J. J.; Xing, G. Z. Yi, J. B.; Li, S.; Chen, T.; Ionescu, M.

    2014-01-06

    Cluster free, Co (3d) and Eu (4f) doped ZnO thin films were prepared using ion implantation technique accompanied by post annealing treatments. Compared with the mono-doped ZnO thin films, the samples codoped with Co and Eu exhibit a stronger magnetization with a giant coercivity of 1200?Oe at ambient temperature. This was further verified through x-ray magnetic circular dichroism analysis, revealing the exchange interaction between the Co 3d electrons and the localized carriers induced by Eu{sup 3+} ions codoping. The insight gained with modulating coercivity in magnetic oxides opens up an avenue for applications requiring non-volatility in spintronic devices.

  5. Three-dimensional Ultrathin Planar Lenses by Acoustic Metamaterials

    NASA Astrophysics Data System (ADS)

    Li, Yong; Yu, Gaokun; Liang, Bin; Zou, Xinye; Li, Guangyun; Cheng, Su; Cheng, Jianchun

    2014-10-01

    Acoustic lenses find applications in various areas ranging from ultrasound imaging to nondestructive testing. A compact-size and high-efficient planar acoustic lens is crucial to achieving miniaturization and integration, and should have deep implication for the acoustic field. However its realization remains challenging due to the trade-off between high refractive-index and impedance-mismatch. Here we have designed and experimentally realized the first ultrathin planar acoustic lens capable of steering the convergence of acoustic waves in three-dimensional space. A theoretical approach is developed to analytically describe the proposed metamaterial with hybrid labyrinthine units, which reveals the mechanism of coexistence of high refractive index and well-matched impedance. A hyperbolic gradient-index lens design is fabricated and characterized, which can enhance the acoustic energy by 15 dB at the focal point with very high transmission efficiency. Remarkably, the thickness of the lens is only approximately 1/6 of the operating wavelength. The lens can work within a certain frequency band for which the ratio between the bandwidth and the center frequency reaches 0.74. By tailoring the structure of the metamaterials, one can further reduce the thickness of the lens or even realize other acoustic functionalities, opening new opportunity for manipulation of low-frequency sounds with versatile potential.

  6. Acoustical linear and nonlinear behavior of fatigued titanium alloys

    NASA Astrophysics Data System (ADS)

    Frouin, Jerome Jean

    2001-12-01

    Nondestructive evaluation (NDE) methodology based on linear and nonlinear acoustics has been developed for monitoring the accumulation of damage under cyclic loading. An experimental measurement system using piezoelectric transducers for generation and detection of fundamental and second harmonic acoustic waves in a sample has been developed. The technique has been utilized for characterizing through interrupted fatigue measurements. A few modifications have lead to the development of a system capable of monitoring while the material is being fatigued. Measurements on Ti-6Al-4V dog bone samples under different loading conditions have been conducted. Results of both linear and nonlinear acoustic measurements will be presented. Difficulties of using linear acoustic properties of elastic modulus and attenuation to characterize fatigue are presented. Observation of large changes (up to 200%) in the nonlinear acoustic parameter of the material during fatigue is presented. Changes in the nonlinear acoustic parameter due to fatigue are related to continuous gradual changes in the microstructure of the material. This is supported by transmission electron microscopic imaging of microstructure in the material fatigued to different levels. The reliability, robustness and limitation of utilizing the nonlinear acoustic parameter for characterization of fatigue damage are discussed.

  7. Acoustic levitator for containerless measurements on low temperature liquids

    SciTech Connect

    Benmore, Chris J; Weber, Richard; Neuefeind, Joerg C; Rey, Charles A A

    2009-01-01

    A single-axis acoustic levitator was constructed and used to levitate liquid and solid drops at temperatures from -40 to +40 C. The levitator consisted of: (i) two acoustic transducers mounted on a rigid vertical support that was bolted to an optical breadboard, (ii) a acoustic power supply that controlled acoustic intensity, relative phase of the drive to the transducers, and could modulate the acoustic forces at frequencies up to 1kHz, (iii) a video camera, and (iv) a system for providing a stream of controlled temperature gas flow over the sample. The acoustic transducers were operated at their resonant frequency of ~ 22 kHz and could produce sound pressure levels up to 160 dB. The force applied by the acoustic field could be modulated using a frequency generator to excite oscillations in the sample. Sample temperature was controlled using a modified Cryostream Plus and measured using thermocouples and an infrared thermal imager. The levitator was installed at x-ray beamline 11 ID-C at the Advanced Photon Source and used to investigate the structure of supercooled liquids.

  8. Three-dimensional ultrathin planar lenses by acoustic metamaterials.

    PubMed

    Li, Yong; Yu, Gaokun; Liang, Bin; Zou, Xinye; Li, Guangyun; Cheng, Su; Cheng, Jianchun

    2014-01-01

    Acoustic lenses find applications in various areas ranging from ultrasound imaging to nondestructive testing. A compact-size and high-efficient planar acoustic lens is crucial to achieving miniaturization and integration, and should have deep implication for the acoustic field. However its realization remains challenging due to the trade-off between high refractive-index and impedance-mismatch. Here we have designed and experimentally realized the first ultrathin planar acoustic lens capable of steering the convergence of acoustic waves in three-dimensional space. A theoretical approach is developed to analytically describe the proposed metamaterial with hybrid labyrinthine units, which reveals the mechanism of coexistence of high refractive index and well-matched impedance. A hyperbolic gradient-index lens design is fabricated and characterized, which can enhance the acoustic energy by 15 dB at the focal point with very high transmission efficiency. Remarkably, the thickness of the lens is only approximately 1/6 of the operating wavelength. The lens can work within a certain frequency band for which the ratio between the bandwidth and the center frequency reaches 0.74. By tailoring the structure of the metamaterials, one can further reduce the thickness of the lens or even realize other acoustic functionalities, opening new opportunity for manipulation of low-frequency sounds with versatile potential. PMID:25354997

  9. A Reconstruction Algorithm of Magnetoacoustic Tomography with Magnetic Induction for Acoustically Inhomogeneous Tissue

    PubMed Central

    Zhou, Lian; Zhu, Shanan

    2014-01-01

    Magnetoacoustic tomography with Magnetic Induction (MAT-MI) is a noninvasive electrical conductivity imaging approach that measures ultrasound wave induced by magnetic stimulation, for reconstructing the distribution of electrical impedance in biological tissue. Existing reconstruction algorithms for MAT-MI are based on the assumption that the acoustic properties in the tissue are homogeneous. However, the tissue in most parts of human body, has heterogeneous acoustic properties, which leads to potential distortion and blurring of small buried objects in the impedance images. In the present study, we proposed a new algorithm for MAT-MI to image the impedance distribution in tissues with inhomogeneous acoustic speed distributions. With a computer head model constructed from MR images of a human subject, a series of numerical simulation experiments were conducted. The present results indicate that the inhomogeneous acoustic properties of tissues in terms of speed variation can be incorporated in MAT-MI imaging. PMID:24845284

  10. Nonlinear acoustics in biomedical ultrasound

    NASA Astrophysics Data System (ADS)

    Cleveland, Robin O.

    2015-10-01

    Ultrasound is widely used to image inside the body; it is also used therapeutically to treat certain medical conditions. In both imaging and therapy applications the amplitudes employed in biomedical ultrasound are often high enough that nonlinear acoustic effects are present in the propagation: the effects have the potential to be advantageous in some scenarios but a hindrance in others. In the case of ultrasound imaging the nonlinearity produces higher harmonics that result in images of greater quality. However, nonlinear effects interfere with the imaging of ultrasound contrast agents (typically micron sized bubbles with a strong nonlinear response of their own) and nonlinear effects also result in complications when derating of pressure measurements in water to in situ values in tissue. High intensity focused ultrasound (HIFU) is emerging as a non-invasive therapeutic modality which can result in thermal ablation of tissue. For thermal ablation, the extra effective attenuation resulting from nonlinear effects can result in enhanced heating of tissue if shock formation occurs in the target region for ablation - a highly desirable effect. However, if nonlinearity is too strong it can also result in undesired near-field heating and reduced ablation in the target region. The disruption of tissue (histotripsy) and fragmentation of kidney stones (lithotripsy) exploits shock waves to produce mechanically based effects, with minimal heating present. In these scenarios it is necessary for the waves to be of sufficient amplitude that a shock exists when the waveform reaches the target region. This talk will discuss how underlying nonlinear phenomenon act in all the diagnostic and therapeutic applications described above.

  11. Spacecraft Internal Acoustic Environment Modeling

    NASA Technical Reports Server (NTRS)

    Allen, Christopher; Chu, S. Reynold

    2008-01-01

    The objective of the project is to develop an acoustic modeling capability, based on commercial off-the-shelf software, to be used as a tool for oversight of the future manned Constellation vehicles to ensure compliance with acoustic requirements and thus provide a safe and habitable acoustic environment for the crews, and to validate developed models via building physical mockups and conducting acoustic measurements.

  12. Latticed pentamode acoustic cloak.

    PubMed

    Chen, Yi; Liu, Xiaoning; Hu, Gengkai

    2015-01-01

    We report in this work a practical design of pentamode acoustic cloak with microstructure. The proposed cloak is assembled by pentamode lattice made of a single-phase solid material. The function of rerouting acoustic wave round an obstacle has been demonstrated numerically. It is also revealed that shear related resonance due to weak shear resistance in practical pentamode lattices punctures broadband feature predicted based on ideal pentamode cloak. As a consequence, the latticed pentamode cloak can only conceal the obstacle in segmented frequency ranges. We have also shown that the shear resonance can be largely reduced by introducing material damping, and an improved broadband performance can be achieved. These works pave the way for experimental demonstration of pentamode acoustic cloak. PMID:26503821

  13. BBN and structural acoustics

    NASA Astrophysics Data System (ADS)

    Lyon, Richard H.

    2001-05-01

    Leo Beranek, Dick Bolt, and Bob Newman founded a company based on technical excellence and client service-BBN. The early services were oriented to noise control and architectural acoustics, but these led fairly quickly over about a decade into several related fields. One such field, now called ``structural acoustics,'' arose from activities in noise control where the radiated sound due to vibrations of the machine caused problems. Commercial work on such problems was later augmented by work for the US Navy, the Air Force, and NASA. In the mid- and late-1950s Ira Dyer built the group that during the course of about the next decade developed the field of structural acoustics, with emphasis on statistical modeling and with applications to ships, aircraft, and space launch vehicles. The author will present some of his personal remembrances of this second decade, with particular emphasis on the development of statistical energy analysis.

  14. Latticed pentamode acoustic cloak

    NASA Astrophysics Data System (ADS)

    Chen, Yi; Liu, Xiaoning; Hu, Gengkai

    2015-10-01

    We report in this work a practical design of pentamode acoustic cloak with microstructure. The proposed cloak is assembled by pentamode lattice made of a single-phase solid material. The function of rerouting acoustic wave round an obstacle has been demonstrated numerically. It is also revealed that shear related resonance due to weak shear resistance in practical pentamode lattices punctures broadband feature predicted based on ideal pentamode cloak. As a consequence, the latticed pentamode cloak can only conceal the obstacle in segmented frequency ranges. We have also shown that the shear resonance can be largely reduced by introducing material damping, and an improved broadband performance can be achieved. These works pave the way for experimental demonstration of pentamode acoustic cloak.

  15. Acoustic particle separation

    NASA Technical Reports Server (NTRS)

    Barmatz, M. B.; Stoneburner, J. D.; Jacobi, N.; Wang, T. (inventors)

    1985-01-01

    A method is described which uses acoustic energy to separate particles of different sizes, densities, or the like. The method includes applying acoustic energy resonant to a chamber containing a liquid of gaseous medium to set up a standing wave pattern that includes a force potential well wherein particles within the well are urged towards the center, or position of minimum force potential. A group of particles to be separated is placed in the chamber, while a non-acoustic force such as gravity is applied, so that the particles separate with the larger or denser particles moving away from the center of the well to a position near its edge and progressively smaller lighter particles moving progressively closer to the center of the well. Particles are removed from different positions within the well, so that particles are separated according to the positions they occupy in the well.

  16. Latticed pentamode acoustic cloak

    PubMed Central

    Chen, Yi; Liu, Xiaoning; Hu, Gengkai

    2015-01-01

    We report in this work a practical design of pentamode acoustic cloak with microstructure. The proposed cloak is assembled by pentamode lattice made of a single-phase solid material. The function of rerouting acoustic wave round an obstacle has been demonstrated numerically. It is also revealed that shear related resonance due to weak shear resistance in practical pentamode lattices punctures broadband feature predicted based on ideal pentamode cloak. As a consequence, the latticed pentamode cloak can only conceal the obstacle in segmented frequency ranges. We have also shown that the shear resonance can be largely reduced by introducing material damping, and an improved broadband performance can be achieved. These works pave the way for experimental demonstration of pentamode acoustic cloak. PMID:26503821

  17. [Imaging].

    PubMed

    Chevrot, A; Drap, J L; Godefroy, D; Dupont, A M; Pessis, E; Sarazin, L; Minoui, A

    1997-01-01

    The panoply of imaging techniques useful in podology is essentially limited to X-rays. Standard "standing" and "lying" X-rays furnish most of the required information. Arthrography is sometimes performed, in particular for trauma or tumour of the ankle. CT scan and MRI make a decisive contribution in difficult cases, notably in fractures and in small fractures without displacement. The two latter techniques are useful in tendon, ligament and muscular disorders, where echography is also informative. Rigorous analysis of radiographies and a good knowledge of foot disorders make these imaging techniques efficacious. PMID:9035538

  18. Acoustically Induced Vibration of Structures: Reverberant Vs. Direct Acoustic Testing

    NASA Technical Reports Server (NTRS)

    Kolaini, Ali R.; O'Connell, Michael R.; Tsoi, Wan B.

    2009-01-01

    Large reverberant chambers have been used for several decades in the aerospace industry to test larger structures such as solar arrays and reflectors to qualify and to detect faults in the design and fabrication of spacecraft and satellites. In the past decade some companies have begun using direct near field acoustic testing, employing speakers, for qualifying larger structures. A limited test data set obtained from recent acoustic tests of the same hardware exposed to both direct and reverberant acoustic field testing has indicated some differences in the resulting structural responses. In reverberant acoustic testing, higher vibration responses were observed at lower frequencies when compared with the direct acoustic testing. In the case of direct near field acoustic testing higher vibration responses appeared to occur at higher frequencies as well. In reverberant chamber testing and direct acoustic testing, standing acoustic modes of the reverberant chamber or the speakers and spacecraft parallel surfaces can strongly couple with the fundamental structural modes of the test hardware. In this paper data from recent acoustic testing of flight hardware, that yielded evidence of acoustic standing wave coupling with structural responses, are discussed in some detail. Convincing evidence of the acoustic standing wave/structural coupling phenomenon will be discussed, citing observations from acoustic testing of a simple aluminum plate. The implications of such acoustic coupling to testing of sensitive flight hardware will be discussed. The results discussed in this paper reveal issues with over or under testing of flight hardware that could pose unanticipated structural and flight qualification issues. Therefore, it is of paramount importance to understand the structural modal coupling with standing acoustic waves that has been observed in both methods of acoustic testing. This study will assist the community to choose an appropriate testing method and test setup in the planning stages.

  19. Acoustics careers for engineers

    NASA Astrophysics Data System (ADS)

    Hansen, Uwe J.

    2001-05-01

    Many acoustics opportunities in industry, government laboratories, and academics rely on a background in mechanical engineering, electrical engineering, or physics. Acoustics deals principally with generation, propagation, and perception of sound. Engineering application, include among many other things, the study and control of structural vibrations, machinery analysis and maintenance, and industrial noise control. Thus, for example, the aircraft industry employs engineers to study vibrational characteristics of items such as turbine blades or entire fuselage assemblies. Among the many techniques utilized are holographic interferometry and modal analysis. Some of these methods will be illustrated.

  20. Acoustic tooth cleaner

    NASA Technical Reports Server (NTRS)

    Heyman, J. S. (inventor)

    1982-01-01

    An acoustic oral hygiene unit is described that uses acoustic energy to oscillate mild abrasive particles in a water suspension which is then directed in a low pressure stream onto the teeth. The oscillating abrasives scrub the teeth clean removing food particles, plaque, calculous, and other foreign material from tooth surfaces, interproximal areas, and tooth-gingiva interface more effectively than any previous technique. The relatively low power output and the basic design makes the invention safe and convenient for everyday use in the home without special training. This invention replaces all former means of home dental prophylaxis, and requires no augmentation to fulfill all requirements for daily oral hygienic care.

  1. Electromechanical acoustic liner

    NASA Technical Reports Server (NTRS)

    Sheplak, Mark (Inventor); Cattafesta, III, Louis N. (Inventor); Nishida, Toshikazu (Inventor); Horowitz, Stephen Brian (Inventor)

    2007-01-01

    A multi-resonator-based system responsive to acoustic waves includes at least two resonators, each including a bottom plate, side walls secured to the bottom plate, and a top plate disposed on top of the side walls. The top plate includes an orifice so that a portion of an incident acoustical wave compresses gas in the resonators. The bottom plate or the side walls include at least one compliant portion. A reciprocal electromechanical transducer coupled to the compliant portion of each of the resonators forms a first and second transducer/compliant composite. An electrical network is disposed between the reciprocal electromechanical transducer of the first and second resonator.

  2. Densitometry By Acoustic Levitation

    NASA Technical Reports Server (NTRS)

    Trinh, Eugene H.

    1989-01-01

    "Static" and "dynamic" methods developed for measuring mass density of acoustically levitated solid particle or liquid drop. "Static" method, unknown density of sample found by comparison with another sample of known density. "Dynamic" method practiced with or without gravitational field. Advantages over conventional density-measuring techniques: sample does not have to make contact with container or other solid surface, size and shape of samples do not affect measurement significantly, sound field does not have to be know in detail, and sample can be smaller than microliter. Detailed knowledge of acoustic field not necessary.

  3. Classroom Materials from the Acoustical Society of America

    NASA Astrophysics Data System (ADS)

    Adams, W. K.; Clark, A.; Schneider, K.

    2013-09-01

    As part of the new education initiatives of the Acoustical Society of America (ASA), an activity kit for teachers that includes a variety of lessons addressing acoustics for a range of students (K-12) has been created. The "Sound and Music Activity Kit" is free to K-12 teachers. It includes materials sufficient to teach a class of 30 students plus a USB thumb drive containing 47 research-based, interactive, student-tested lessons, laboratory exercises, several assessments, and video clips of a class using the materials. ASA has also partnered with both the Optical Society of America (OSA) and the American Association of Physics Teachers. AAPT Physics Teaching Resource Agents (PTRA) have reviewed the lessons along with members of the ASA Teacher Activity Kit Committee. Topics include basic learning goals for teaching the physics of sound with examples and applications relating to medical imaging, animal bioacoustics, physical and psychological acoustics, speech, audiology, and architectural acoustics.

  4. Sound Pressure Level Gain in an Acoustic Metamaterial Cavity

    NASA Astrophysics Data System (ADS)

    Song, Kyungjun; Kim, Kiwon; Hur, Shin; Kwak, Jun-Hyuk; Park, Jihyun; Yoon, Jong Rak; Kim, Jedo

    2014-12-01

    The inherent attenuation of a homogeneous viscous medium limits radiation propagation, thereby restricting the use of many high-frequency acoustic devices to only short-range applications. Here, we design and experimentally demonstrate an acoustic metamaterial localization cavity which is used for sound pressure level (SPL) gain using double coiled up space like structures thereby increasing the range of detection. This unique behavior occurs within a subwavelength cavity that is 1/10th of the wavelength of the incident acoustic wave, which provides up to a 13 dB SPL gain. We show that the amplification results from the Fabry-Perot resonance of the cavity, which has a simultaneously high effective refractive index and effective impedance. We also experimentally verify the SPL amplification in an underwater environment at higher frequencies using a sample with an identical unit cell size. The versatile scalability of the design shows promising applications in many areas, especially in acoustic imaging and underwater communication.

  5. Stochastic Seismic Emission from Acoustic Glories in Solar Active Regions

    NASA Astrophysics Data System (ADS)

    Donea, Alina; Newington, Marie

    2011-01-01

    Helioseismic images of active regions show enhanced seismic emission in 5 mHz oscillations in a halo surrounding the active region called the "acoustic glory". In this paper we analyse the high-frequency power excess surrounding two active regions that occurred during the "shy" ascending phase of the solar cycle 24, at the beginning of 2010. This study compares the acoustic properties of seismic emission from acoustic glories with that from the quiet Sun. The power distribution of quiet-Sun seismic emission far from solar activity is exponential, as for random Gaussian noise, and therefore not episodic. The magnitudes of the acoustic glories and their seismic structure allow us to make predictions of the seismic behaviour of active regions and compare the data with present theoretical models.

  6. JOINT ACOUSTIC-VIDEO FINGERPRINTING OF VEHICLES, PART I , R. Chellappa

    E-print Network

    Cevher, Volkan

    and Image Processing, Georgia Institute of Technology, Atlanta GA 30332 ABSTRACT We address vehicle classification and mensuration problems using acous- tic and video sensors. In this paper, we show how a single passive acoustic sensor that records the vehicle's drive-by noise. The acoustic wave

  7. Proceedings of the International Conference "Underwater Acoustic Measurements: Technologies &Results" Heraklion, Crete, Greece, 28th

    E-print Network

    Gerstoft, Peter

    that coherent noise field between station pairs can be used for seismic imaging purposes. Keywords: Orion, Noise with ambient noise. Noise data from fixed acoustic and seismic sensors can be used to study the ocean structure &Results" Heraklion, Crete, Greece, 28th June 1st July 2005 PASSIVE ACOUSTIC AND SEISMIC TOMOGRAPHY

  8. A contrast source method for nonlinear acoustic wave fields in media with spatially inhomogeneous attenuation

    E-print Network

    van Vliet, Lucas J.

    attenuation L. Demia) and K. W. A. van Dongen Laboratory of Acoustical Imaging and Sound Control, Faculty that attenuation is an important phenomenon in medical ultrasound. Attenuation is particularly important for medical applications based on nonlinear acoustics, since higher harmonics experience higher attenuation

  9. Ultrasonic Beamforming and Steering for Acoustic Radiation Force Optical Coherence Elastography

    E-print Network

    Afshari, Ehsan

    Ultrasonic Beamforming and Steering for Acoustic Radiation Force Optical Coherence Elastography to the sample and by modulating the acoustic radiation force, highly localized `palpation' can be performed that controls OCT image acquisition. To generate enough pressure from each transducer, it is necessary to use

  10. Fundamentals of Acoustics. Psychoacoustics and Hearing. Acoustical Measurements

    NASA Technical Reports Server (NTRS)

    Begault, Durand R.; Ahumada, Al (Technical Monitor)

    1997-01-01

    These are 3 chapters that will appear in a book titled "Building Acoustical Design", edited by Charles Salter. They are designed to introduce the reader to fundamental concepts of acoustics, particularly as they relate to the built environment. "Fundamentals of Acoustics" reviews basic concepts of sound waveform frequency, pressure, and phase. "Psychoacoustics and Hearing" discusses the human interpretation sound pressure as loudness, particularly as a function of frequency. "Acoustic Measurements" gives a simple overview of the time and frequency weightings for sound pressure measurements that are used in acoustical work.

  11. Resonant acoustic radiation force optical coherence elastography

    NASA Astrophysics Data System (ADS)

    Qi, Wenjuan; Li, Rui; Ma, Teng; Li, Jiawen; Kirk Shung, K.; Zhou, Qifa; Chen, Zhongping

    2013-09-01

    We report on a resonant acoustic radiation force optical coherence elastography (ARF-OCE) technique that uses mechanical resonant frequency to characterize and identify tissues of different types. The linear dependency of the resonant frequency on the square root of Young's modulus was validated on silicone phantoms. Both the frequency response spectrum and the 3D imaging results from the agar phantoms with hard inclusions confirmed the feasibility of deploying the resonant frequency as a mechanical contrast for tissue imaging. Furthermore, the results of resonant ARF-OCE imaging of a post-mortem human coronary artery with atherosclerosis demonstrate the potential of the resonant ARF-OCE as a non-invasive method for imaging and characterizing vulnerable plaques.

  12. Intervalence charge transfer luminescence: Interplay between anomalous and 5d - 4f emissions in Yb-doped fluorite-type crystals

    NASA Astrophysics Data System (ADS)

    Barandiarn, Zoila; Seijo, Luis

    2014-12-01

    In this paper, we report the existence of intervalence charge transfer (IVCT) luminescence in Yb-doped fluorite-type crystals associated with Yb2+-Yb3+ mixed valence pairs. By means of embedded cluster, wave function theory ab initio calculations, we show that the widely studied, very broad band, anomalous emission of Yb2+-doped CaF2 and SrF2, usually associated with impurity-trapped excitons, is, rather, an IVCT luminescence associated with Yb2+-Yb3+ mixed valence pairs. The IVCT luminescence is very efficiently excited by a two-photon upconversion mechanism where each photon provokes the same strong 4f14-1A1g? 4f13(2F7/2)5deg-1T1u absorption in the Yb2+ part of the pair: the first one, from the pair ground state; the second one, from an excited state of the pair whose Yb3+ moiety is in the higher 4f13(2F5/2) multiplet. The Yb2+-Yb3+ ? Yb3+-Yb2+ IVCT emission consists of an Yb2+ 5deg ? Yb3+ 4f7/2 charge transfer accompanied by a 4f7/2 ? 4f5/2 deexcitation within the Yb2+ 4f13 subshell: [2F5/25deg,2F7/2] ? [2F7/2,4f14]. The IVCT vertical transition leaves the oxidized and reduced moieties of the pair after electron transfer very far from their equilibrium structures; this explains the unexpectedly large band width of the emission band and its low peak energy, because the large reorganization energies are subtracted from the normal emission. The IVCT energy diagrams resulting from the quantum mechanical calculations explain the different luminescent properties of Yb-doped CaF2, SrF2, BaF2, and SrCl2: the presence of IVCT luminescence in Yb-doped CaF2 and SrF2; its coexistence with regular 5d-4f emission in SrF2; its absence in BaF2 and SrCl2; the quenching of all emissions in BaF2; and the presence of additional 5d-4f emissions in SrCl2 which are absent in SrF2. They also allow to interpret and reproduce recent experiments on transient photoluminescence enhancement in Yb2+-doped CaF2 and SrF2, the appearance of Yb2+ 4f-5d absorption bands in the excitation spectra of the IR Yb3+ emission in partly reduced CaF2:Yb3+ samples, and to identify the broadband observed in the excitation spectrum of the so far called anomalous emission of SrF2:Yb2+ as an IVCT absorption, which corresponds to an Yb2+ 4f5/2 ? Yb3+ 4f7/2 electron transfer.

  13. Subharmonic phased array for crack evaluation using surface acoustic wave

    NASA Astrophysics Data System (ADS)

    Ouchi, Akihiro; Sugawara, Azusa; Ohara, Yoshikazu; Yamanaka, Kazushi

    2015-07-01

    To accurately measure closed crack length, we proposed an imaging method using a subharmonic phased array for crack evaluation using surface acoustic waves (SAW SPACE) with water immersion. We applied SAW SPACE to the hole specimen in a fundamental array (FA) image. The hole was imaged with high resolution. Subsequently, SAW SPACE was applied to fatigue crack and stress corrosion crack (SCC) specimens. A fatigue crack was imaged in FA and subharmonic array (SA) images, and the length of this particular fatigue crack measured in the images was almost the same as that measured by optical observation. The SCC was imaged and its length was accurately measured in the SA image, whereas it was underestimated in the FA image and by optical observation. Thus, we demonstrated that SAW SPACE with water immersion is useful for the accurate measurement of closed crack length and for imaging the distribution of open and closed parts of cracks with high resolution.

  14. Investigation on the upconversion luminescence of Sr3AlO4F:Yb3+, Er3+, Ho3+ phosphors

    NASA Astrophysics Data System (ADS)

    Zhang, Jia; Zhai, Zhangyin

    2015-12-01

    To develop new emission-tunable upconversion (UC) phosphors, the Sr3AlO4F:5%Yb3+, xEr3+, yHo3+ (0?x?1%, 0?y?1%) samples were prepared by conversional solid-state reaction method, and their luminescence properties upon 980nm excitation were studied. Upon 980nm excitation, Yb3+-Er3+ codoped Sr3AlO4F shows a predominant emission peak between 645 and 700nm which is attributed to the 4F9/2-4I15/2 transition of Er3+, and the Er3+ green emissions have been almost quenched. In this case, the yellowish green emitting light is obtained. The possible reason was interpreted by the energy level diagram and the proposed UC mechanism. For Yb3+-Ho3+ codoped Sr3AlO4F, three emissions are observed obviously which are all derived from the Ho3+ ion. The corresponding chromaticity coordinates indicate a red emission has been gained. To realize the tunable emission, the typical Sr3AlO4F:5%Yb3+, 0.2%Er3+, 1%Ho3+ phosphor was developed, and its emission spectrum includes the emission peaks of both Er3+ and Ho3+. Correspondingly, the sample gives a yellow emission.

  15. Residual and Recurrent Acoustic Neuroma in Hearing Preservation Procedures

    PubMed Central

    Mazzoni, Antonio; Calabrese, Vincenzo; Moschini, Luca

    1996-01-01

    Magnetic resonance imaging with gadolinium DTPA is currently the most accurate method for detecting small intracanalicular yestibular schwannomas. This imaging modality is not nearly as clear in diagnosis of a small residual or recurrent neuroma after a hearing preservation procedure. This study looked for gadolinium-enhanced MRI images mimicking recurrent lesions in 104 consecutive cases of unilateral acoustic neuroma removed with a hearing preservation technique by the retrosigmoid transmeatal approach. A number of cases with enhancing MRI images in the internal anditory canal were reoperated, permitting the histologic examination of the enhancing tissue. Criteria for the MRI diagnosis of residual-recurrent acoustic neuroma are presented, along with the short-to mid-term rate of residual-recurrent tumor. ImagesFigure 2Figure 3Figure 4Figure 5Figure 6 PMID:17170984

  16. Observation of the surface 4f state of CePd{sub 7} by means of the resonant-inverse-photoemission study at the Ce 4d absorption edge

    SciTech Connect

    Kanai, K.; Tezuka, Y.; Fujisawa, M.; Harada, Y.; Shin, S.; Schmerber, G.; Kappler, J.P.; Parlebas, J.C.; Kotani, A.

    1997-01-01

    The resonant inverse photoemission study (RIPES) of CePd{sub 7}, has been carried out at the Ce 4d{r_arrow}4f absorption edge. The strong resonant enhancement of the 4f cross section enables us to distinguish two 4f components in the empty electronic state near the Fermi level. The incidence-angle dependence of the RIPES indicates a clear difference between ground-state configurations at the bulk and surface. It is found that the former shows a strongly hybridized 4f state, while the latter shows a localized 4f character. The angle dependence of the RIPES of {alpha}-Ce metal has been also carried out and similar results as those of CePd{sub 7} were obtained. The RIPES at the Ce 4d{r_arrow}4f edge is found to be a powerful method to investigate the surface 4f state. {copyright} {ital 1997} {ital The American Physical Society}

  17. Material Property Measurement in Hostile Environments using Laser Acoustics

    SciTech Connect

    Ken L. Telschow

    2004-08-01

    Acoustic methods are well known and have been used to measure various intrinsic material properties, such as, elastic coefficients, density, crystal axis orientation, microstructural texture, and residual stress. Extrinsic properties, such as, dimensions, motion variables or temperature are also readily determined from acoustic methods. Laser acoustics, employing optical generation and detection of elastic waves, has a unique advantage over other acoustic methodsit is noncontacting, uses the sample surface itself for transduction, requires no couplant or invasive sample surface preparation and can be utilized in any hostile environment allowing optical access to the sample surface. In addition, optical generation and detection probe beams can be focused to the micron scale and/or shaped to alter the transduction process with a degree of control not possible using contact transduction methods. Laser methods are amenable to both continuous wave and pulse-echo measurements and have been used from Hz to 100s of GHz (time scales from sec to psec) and with amplitudes sufficient to fracture materials. This paper shall review recent applications of laser acoustic methods to determining material properties in hostile environments that preclude the use of contacting transduction techniques. Example environments include high temperature (>1000C) sintering and molten metal processing, thin film deposition by plasma techniques, materials moving at high velocity during the fabrication process and nuclear high radiation regions. Recent technological advances in solid-state lasers and telecommunications have greatly aided the development and implementation of laser acoustic methods, particularly at ultra high frequencies. Consequently, laser acoustic material property measurements exhibit high precision and reproducibility today. In addition, optical techniques provide methods of imaging acoustic motion that is both quantitative and rapid. Possible future directions for laser acoustics shall be discussed drawing from examples in materials science, microelectronic and nuclear fields.

  18. Characterization of human breast cancer by scanning acoustic microscopy

    NASA Astrophysics Data System (ADS)

    Chen, Di; Malyarenko, Eugene; Seviaryn, Fedar; Yuan, Ye; Sherman, Mark; Bandyopadhyay, Sudeshna; Gierach, Gretchen; Greenway, Christopher W.; Maeva, Elena; Strumban, Emil; Duric, Neb; Maev, Roman

    2013-03-01

    Objectives: The purpose of this study was to characterize human breast cancer tissues by the measurement of microacoustic properties. Methods: We investigated eight breast cancer patients using acoustic microscopy. For each patient, seven blocks of tumor tissue were collected from seven different positions around a tumor mass. Frozen sections (10 micrometer, ?m) of human breast cancer tissues without staining and fixation were examined in a scanning acoustic microscope with focused transducers at 80 and 200 MHz. Hematoxylin and Eosin (H and E) stained sections from the same frozen breast cancer tissues were imaged by optical microscopy for comparison. Results: The results of acoustic imaging showed that acoustic attenuation and sound speed in cancer cell-rich tissue regions were significantly decreased compared with the surrounding tissue regions, where most components are normal cells/tissues, such as fibroblasts, connective tissue and lymphocytes. Our observation also showed that the ultrasonic properties were influenced by arrangements of cells and tissue patterns. Conclusions: Our data demonstrate that attenuation and sound speed imaging can provide biomechanical information of the tumor and normal tissues. The results also demonstrate the potential of acoustic microscopy as an auxiliary method for operative detection and localization of cancer affected regions.

  19. Acoustic velocities in petroleum oils

    SciTech Connect

    Wang, Z. ); Nur, A.M. . Mound); Batzle, M.L. )

    1990-02-01

    Results of laboratory experiments on acoustic-wave velocities in oils show that the measured acoustic velocities are strong functions of both temperature and pressure. The experimental results are discussed in light of existing liquid state theories and models to interpret and understand the acoustic-velocity behaviors of oils. Correlations are made between acoustic velocity and temperature, pressure, API gravity, and molecular weight. Empirical equations are established to calculate acoustic velocities in oils with known API gravities. Various applications or potential applications of the experimental results are also discussed.

  20. Micro acoustic spectrum analyzer

    DOEpatents

    Schubert, W. Kent; Butler, Michael A.; Adkins, Douglas R.; Anderson, Larry F.

    2004-11-23

    A micro acoustic spectrum analyzer for determining the frequency components of a fluctuating sound signal comprises a microphone to pick up the fluctuating sound signal and produce an alternating current electrical signal; at least one microfabricated resonator, each resonator having a different resonant frequency, that vibrate in response to the alternating current electrical signal; and at least one detector to detect the vibration of the microfabricated resonators. The micro acoustic spectrum analyzer can further comprise a mixer to mix a reference signal with the alternating current electrical signal from the microphone to shift the frequency spectrum to a frequency range that is a better matched to the resonant frequencies of the microfabricated resonators. The micro acoustic spectrum analyzer can be designed specifically for portability, size, cost, accuracy, speed, power requirements, and use in a harsh environment. The micro acoustic spectrum analyzer is particularly suited for applications where size, accessibility, and power requirements are limited, such as the monitoring of industrial equipment and processes, detection of security intrusions, or evaluation of military threats.