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1

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

PubMed

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

Chen, Zhanxu; Tang, Zhilie; Wan, Wei

2007-04-16

2

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

PubMed

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

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

2008-04-14

3

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

PubMed Central

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

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

2010-01-01

4

Acoustic subwavelength imaging of subsurface objects with acoustic resonant metalens  

NASA Astrophysics Data System (ADS)

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

Cheng, Ying; Zhou, Chen; Wei, Qi; Wu, DaJian; Liu, XiaoJun

2013-11-01

5

Acoustic subwavelength imaging of subsurface objects with acoustic resonant metalens  

SciTech Connect

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

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

2013-11-25

6

Acoustic imaging for nondestructive evaluation  

Microsoft Academic Search

The application of acoustic imaging techniques to non-destructive testing (NDT) of materials is discussed. After a description of the standard NDT techniques employed in the field and some examples of mechanically scanned imaging devices, most of the paper is devoted to a description of electronically scanned and focused systems. As holographic techniques are described by Ahmed et al. [22] in

G. S. Kino

1979-01-01

7

Acoustic Waves in Medical Imaging and Diagnostics  

PubMed Central

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

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

2013-01-01

8

Reflective echo tomographic imaging using acoustic beams  

SciTech Connect

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

Kisner, Roger; Santos-Villalobos, Hector J

2014-11-25

9

Essential physics of nuclear acoustic resonance imaging  

Microsoft Academic Search

Nuclear acoustic resonance (NAR), like nuclear magnetic resonance (NMR), can be used as a spectroscopic imaging tool to detect and characterize soft tissue densities and differences on the atomic scale. Whereas NMR uses electromagnetic radiation to induce energy level transitions, NAR uses acoustic radiation. The frequency of this radiation is typically 1 to 100 MHz; NAR imaging therefore uses ultrasonic

Ross M. Henderson

1997-01-01

10

Acoustic 3D imaging of dental structures  

SciTech Connect

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

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

1997-02-01

11

Research on pulse wave acoustical holographic imaging  

Microsoft Academic Search

In order to improve the resolution of acoustical holographic imaging, a new method, i.e. pulse wave holographic imaging has been discussed in the article. Theoretical analysis and computer simulation indicate that the pulse wave holographic imaging has a better resolution than the continuous wave one. In addition, picking up the phase information of reconstructed waves and using deconvolution technology in

Jianzheng Cheng; Dejun Zhang

2010-01-01

12

Essential physics of nuclear acoustic resonance imaging  

NASA Astrophysics Data System (ADS)

Nuclear acoustic resonance (NAR), like nuclear magnetic resonance (NMR), can be used as a spectroscopic imaging tool to detect and characterize soft tissue densities and differences on the atomic scale. Whereas NMR uses electromagnetic radiation to induce energy level transitions, NAR uses acoustic radiation. The frequency of this radiation is typically 1 to 100 MHz; NAR imaging therefore uses ultrasonic energy to induce transitions among the nuclear spin energy levels. By means of piezoelectric transducers, polarized acoustic waves are generated and propagated within a specimen. If these perturbations are in resonance with the specimen's nuclear spin system, then the acoustic waves will periodically modulate an internal magnetic dipole or electric quadrupole interaction as acoustic energy is absorbed. The measurement of this acoustic energy absorption is analogous to the computation of the spin-lattice relaxation time, T1, caused by the release of radiofrequency energy into the surrounding lattice of an excited nucleus and used in magnetic resonance imaging. Accordingly, NAR imaging combines the tools of ultrasound with the techniques of MRI to yield a new and potentially valuable medical imaging modality. The purpose of this paper is to discuss the essential physics of NAR, and to suggest how NAR signals can be processed for medical imaging.

Henderson, Ross M.

1997-05-01

13

Pulsed-Source Interferometry in Acoustic Imaging  

NASA Technical Reports Server (NTRS)

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

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

2003-01-01

14

Imaging of Acoustic Waves in Sand  

SciTech Connect

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

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

2003-08-01

15

High resolution underwater acoustic imaging  

Microsoft Academic Search

A high resolution underwater imaging system using sparse array technology has been developed and tested in turbid waters around Australia. High resolution 3D imaging implies many voxels. The present system can image 103×103×4×10 3 voxels although faster images can be obtained by zooming to a smaller volume of interest. With 3D images, precise dimensions of complex shapes such as pipe

I. S. F. Jones

1999-01-01

16

ACOUSTIC DAYLIGHT IMAGING: VISION IN THE OCEAN  

Microsoft Academic Search

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

Michael J. Buckingham; John R. Potter

1994-01-01

17

15 Acoustic Daylight Imaging in the Michael J. Buckingham  

E-print Network

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

Buckingham, Michael

18

Position-Dependent Defocus Processing for Acoustic Holography Images  

E-print Network

Position-Dependent Defocus Processing for Acoustic Holography Images Ruming Yin,1 Patrick J. Flynn 2002 ABSTRACT: Acoustic holography is a transmission-based ultrasound imaging method that uses optical by acoustic holography requires position-dependent filtering for the enhancement step. It is found

Flynn, Patrick J.

19

Imaging acoustic waves in microscopic wedges  

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

20

Acoustic imaging of subtle porosity variations in ceramics  

NASA Technical Reports Server (NTRS)

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

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

1988-01-01

21

Acoustic and Photoacoustic Molecular Imaging of Cancer  

PubMed Central

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

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

2014-01-01

22

Quantitative Photo-Acoustic Imaging of Small Absorbers Habib Ammari  

E-print Network

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

Kang, Hyeonbae

23

Interpreting Underwater Acoustic Images of the Upper Ocean Boundary Layer  

ERIC Educational Resources Information Center

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

Ulloa, Marco J.

2007-01-01

24

Imaging concert hall acoustics using visual and audio cameras  

Microsoft Academic Search

Using a recently developed real time audio camera, that uses the output of a spherical microphone array beamformer steered in all directions to create central projection to create acoustic intensity images, we present a technique to measure the acoustics of rooms and halls. A panoramic mosaiced visual image of the space is also create. Since both the visual and the

Adam O'Donovan; Ramani Duraiswami; Dmitry N. Zotkin

2008-01-01

25

Transthoracic Cardiac Acoustic Radiation Force Impulse Imaging  

NASA Astrophysics Data System (ADS)

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

Bradway, David Pierson

26

Passive imaging in nondiffuse acoustic wavefields.  

PubMed

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

Mulargia, Francesco; Castellaro, Silvia

2008-05-30

27

Optimization of a biometric system based on acoustic images.  

PubMed

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

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

2014-01-01

28

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

SciTech Connect

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

Ken L. Telschow

2004-07-01

29

Imaging of the wave field of surface acoustic wave devices  

Microsoft Academic Search

An optical measurement technique for the phase preserving imaging of elastical wave fields of surface acoustic wave devices was developed. This technique uses short pulses from a mode-locked picosecond laser, harmonic mixing, and coherent detection to achieve a measurement bandwidth beyond 1 GHz. It is therefore well suited to perform measurements on surface acoustic wave devices of even the highest

P. Kessler; G. Solkner; K. C. Wagner

1991-01-01

30

Acoustic imaging in a water filled metallic pipe  

SciTech Connect

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

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

1984-04-01

31

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

SciTech Connect

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

Ken Telschow; John D. Larson III

2006-10-01

32

Performance evaluation of a biometric system based on acoustic images.  

PubMed

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

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

2011-01-01

33

Acoustical imaging of high-frequency elastic responses of targets  

NASA Astrophysics Data System (ADS)

Acoustical imaging was used to investigate high-frequency elastic responses to sound of two targets in water. The backscattering of broadband bipolar acoustic pulses by a truncated cylindrical shell was recorded over a wide range of tilt angles [S. F. Morse and P. L. Marston, ``Backscattering of transients by tilted truncated cylindrical shells: time-frequency identification of ray contributions from measurements,'' J. Acoust. Soc. Am. (in press)]. This data set was used to form synthetic aperture images of the target based on the data within different angular apertures. Over a range of viewing angles, the visibility of the cylinder's closest rear corner was significantly enhanced by the meridional flexural wave contribution to the backscattering. In another experiment, the time evolution of acoustic holographic images was used to explore the response of tilted elastic circular disks to tone bursts having frequencies of 250 and 300 kHz. For different tilt angles, specific responses that enhance the backscattering were identified from the time evolution of the images [B. T. Hefner and P. L. Marston, Acoust. Res. Lett. Online 2, 55-60 (2001)]. [Work supported by ONR.

Morse, Scot F.; Hefner, Brian T.; Marston, Philip L.

2002-05-01

34

Imaging of Acoustic Waves in Piezoelectric Ceramics by Coulomb Coupling  

NASA Astrophysics Data System (ADS)

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

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

2012-07-01

35

Acoustic Molecular Imaging and Targeted Drug Delivery with Perfluorocarbon Nanoparticles  

NASA Astrophysics Data System (ADS)

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

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

2005-03-01

36

Epipolar geometry of opti-acoustic stereo imaging.  

PubMed

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

Negahdaripour, Shahriar

2007-10-01

37

Acoustic-resolution photoacoustic imaging system with simple fiber illumination  

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

38

A hierarchical variational Bayesian approximation approach in acoustic imaging  

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

39

Acoustic imaging of underground storage tank wastes  

SciTech Connect

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

Mech, S.J.

1995-09-01

40

a One-Dimensional Phased Array Acoustic Imaging System.  

NASA Astrophysics Data System (ADS)

An acoustic phased array imaging system is a device that uses high frequency sound waves to image the acoustic reflectivity or opacity of objects in an acoustically transparent medium. Its operation is similar to that of phased array radar in that a phase front is synthesized by controlling the phase of the energy radiated from each element of an array of radiators. The resulting beam is electronically translated across the field of view thereby producing a scan of the image field. The acoustic phased array systems described in this dissertation differ from most phased array radar systems in that they were designed to image objects in the near field of the array aperture. The first system could control the phase in increments of 3.14 radians. Unfortunately, this system was unusable due to a very high background level in its focal plane response. Analysis of this effect showed that this background was a direct result of the large phase increment. A computer program was written to look at the effects of reducing the size of this phase step. The computer generated results differed enough from those predicted by the phased array theories to warrant a theoretical investigation. The resulting analyses are presented along with those that predict the effects due to element to element crosstalk, missing elements, and amplitude and phase errors in the radiated acoustic field. The second phased array system was designed using the results of these analyses. A detailed description of the design concepts are presented along with the construction details of this, the multi-phase imaging, system. The focal plane responses of this device are shown to verify the predicted effects the phase increment size.

Bates, Kenneth Norris

1982-03-01

41

Acoustic Imaging in 3D Frank Natterer  

E-print Network

of seismic imaging, namely velocity estimation. In the suggested ultrasound mammography system, the chest from X-ray tomography. It belongs to the family of adjoint methods and can be viewed as a single

Münster, Westfälische Wilhelms-Universität

42

Opto-acoustic breast imaging with co-registered ultrasound  

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

43

Image reconstruction with acoustic radiation force induced shear waves  

NASA Astrophysics Data System (ADS)

Acoustic radiation force may be used to induce localized displacements within tissue. This phenomenon is used in Acoustic Radiation Force Impulse Imaging (ARFI), where short bursts of ultrasound deliver an impulsive force to a small region. The application of this transient force launches shear waves which propagate normally to the ultrasound beam axis. Measurements of the displacements induced by the propagating shear wave allow reconstruction of the local shear modulus, by wave tracking and inversion techniques. Here we present in vitro, ex vivo and in vivo measurements and images of shear modulus. Data were obtained with a single transducer, a conventional ultrasound scanner and specialized pulse sequences. Young's modulus values of 4 kPa, 13 kPa and 14 kPa were observed for fat, breast fibroadenoma, and skin. Shear modulus anisotropy in beef muscle was observed.

McAleavey, Stephen A.; Nightingale, Kathryn R.; Stutz, Deborah L.; Hsu, Stephen J.; Trahey, Gregg E.

2003-05-01

44

Subwavelength imaging by a simple planar acoustic superlens  

NASA Astrophysics Data System (ADS)

We experimentally realized a planar acoustic superlens by a simple structure consisting of periodically arrayed rigid slabs. Based on the excitation of guided modes and the moderate amplification of the evanescent waves, we have broken the diffraction limit and obtained a subwavelength image with a half-power beamwidth of 0.07?. All the experimental results are in good agreement with the theoretical simulations via finite difference time domain method.

Jia, Han; Ke, Manzhu; Hao, Rui; Ye, Yangtao; Liu, Fengming; Liu, Zhengyou

2010-10-01

45

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

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

46

3-D reconstruction of the underwater acoustic images using the GPS positioning and the image matching technology  

Microsoft Academic Search

In this paper we focus on how to reconstruct a 3-D structure of the seabed from a spatial series of the 2-D underwater acoustic images. We developed an original method, which uses a combination of the GPS positioning and the image matching technology to synthesize two or more different acoustic images taken from different viewpoints, and then extract the range

Yuefeng LU; Masaki OSHIMA

2002-01-01

47

Fish population dynamics revealed by instantaneous continental-shelf scale acoustic imaging  

Microsoft Academic Search

Video images of fish population densities over vast areas of the New Jersey continental shelf have been produced from acoustic data collected on a long range bistatic sonar system during the Acoustic Clutter 2003 experiment. Areal fish population densities were obtained after correcting the acoustic data for two-way transmission loss modeled using the range-dependent parabolic equation, spatially varying beampattern of

Purnima Ratilal; Deanelle Symonds; Nicholas C. Makris; Redwood Nero

2005-01-01

48

Identifying Vulnerable Plaques with Acoustic Radiation Force Impulse Imaging  

NASA Astrophysics Data System (ADS)

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

Doherty, Joshua Ryan

49

A Dual Communication and Imaging Underwater Acoustic System  

NASA Astrophysics Data System (ADS)

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

Fu, Tricia C.

50

Feasibility of High Frequency Acoustic Imaging for Inspection of Containments  

SciTech Connect

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

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

1998-08-01

51

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

E-print Network

Correlation of Imaging Sonar Acoustic Shadows and Bathymetry for ROV Terrain-Relative Localization@stanford.edu Abstract-- This paper demonstrates the use of sonar imagery as an automated pilot aid for localization is presented to correlate acoustic shadows in sonar imagery with expected visibility images generated from

52

Acoustic radiation force impulse imaging: in vivo demonstration of clinical feasibility  

Microsoft Academic Search

The clinical viability of a method of acoustic remote palpation, capable of imaging local variations in the mechanical properties of soft tissue using acoustic radiation force impulse (ARFI) imaging, is investigated in vivo. In this method, focused ultrasound (US) is used to apply localized radiation force to small volumes of tissue (2 mm3) for short durations (less than 1 ms)

Kathryn Nightingale; Mary Scott Soo; Roger Nightingale; Gregg Trahey

2002-01-01

53

An acoustic charge transport imager for high definition television applications  

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

54

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

NASA Astrophysics Data System (ADS)

Millimeter-wave holographic imaging techniques have recently been developed for personnel surveillance applications at airports and other high-security checkpoints. Millimeter- wave imaging is useful for this application since millimeter-waves easily pass through common clothing materials yet are reflected from the human body and any items concealed by clothing. This allows a high-resolution imaging system to form an image revealing items concealed on the person imaged. A prototype imaging system developed at Pacific Northwest National Laboratory uses a scanned linear array of millimeter-wave antennas to capture wideband millimeter-wave data in approximately one second. This data is then mathematically reconstructed to form a high- resolution 3D image of the person being scanned. Millimeter- wave imaging has been demonstrated to be effective for detecting concealed weapons on personnel. Another imaging technique which could be applied to the weapon detection problem is acoustic imaging. Like millimeter-waves, ultrasonic acoustic waves can also penetrate clothing, and can be used to form relatively high-resolution images which can reveal concealed weapons on personnel. Acoustic imaging results have been obtained using wideband holographic imaging techniques nearly identical to the imaging techniques used for millimeter-wave imaging. Preliminary imaging results at 50 kHz indicate that acoustic imaging can be used to penetrate some types of common clothing materials. Hard clothing materials, such as leather on vinyl, are essentially opaque to acoustic waves at 50 kHz. In this paper, millimeter-wave and acoustic wave imaging techniques are compared for their effectiveness and suitability in weapon detection imaging systems. Experimental results from both imaging modalities are shown.

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

1997-02-01

55

Detection of Landmines from Acoustic Images Based on Cepstral Coefficients  

NASA Astrophysics Data System (ADS)

This paper introduces a cepstral approach for the automatic detection of landmines from acoustic images. This approach is based on treating the problem of landmine detection as a pattern recognition problem. Cepstral features are extracted from a group of landmine images which are transformed first to 1-D signals by lexicographic ordering. Mel frequency cepstral coefficients (MFCCs) and polynomial shaping coefficients are extracted from these 1-D signals to form a database of features, which can be used to train a neural network with the landmine features. The landmine detection can be performed by extracting features from any new image with the same method used in the training phase. These features are tested with the neural network to decide whether a landmine exists or not. The different domains are tested and compared for efficient feature extraction from the lexicographically ordered 1-D signals. Experimental results show the success of the proposed cepstral approach for landmine detection at low as well as high signal to noise ratios. Results also show that the discrete cosine transform is the most appropriate domain for feature extraction.

Abd El-Samie, Fathi E.

2009-12-01

56

A surface acoustic wave device for obtaining direct electronic Fourier transforms of images  

Microsoft Academic Search

A one-dimensional acoustic surface wave direct electronic Fourier transform (DEFT) camera was fabricated and evaluated. This device employs the elastophotoconductance mechanism (the interaction of a surface acoustic wave with a photo-conductive CdS polycrystalline film), creating electrical signals proportional to a spatial Fourier transform of the image incident on it. In this device, the surface acoustic wave is generated by a

N. T. Yang

1974-01-01

57

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

SciTech Connect

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

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

2002-10-01

58

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

NASA Astrophysics Data System (ADS)

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

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

2012-07-01

59

Negative refraction imaging of acoustic metamaterial lens in the supersonic range  

SciTech Connect

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

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

2014-05-15

60

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

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

61

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

NASA Technical Reports Server (NTRS)

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.

Blackshire, James L.

1997-01-01

62

Acoustic imaging by second harmonic of phase-conjugate wave in inhomogeneous medium  

NASA Astrophysics Data System (ADS)

Application of the supercritical magnetoelastic wave phase conjugation to harmonic imaging in acoustic C-scan microscopy is demonstrated. Second-harmonic generation by phase-conjugate wave is used for improvement of resolution of an imaging system. Possibility to compensate phase aberrations introduced in harmonic image by inhomogeneity of propagation medium is shown experimentally and explained theoretically.

Pyl'nov, Yu.; Pernod, P.; Preobrazhensky, V.

2001-01-01

63

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

PubMed

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

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

2008-01-01

64

An Acoustic Charge Transport Imager for High Definition Television  

NASA Technical Reports Server (NTRS)

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

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

1999-01-01

65

Acoustics  

NASA Technical Reports Server (NTRS)

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

Goodman, Jerry R.; Grosveld, Ferdinand

2007-01-01

66

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

NASA Astrophysics Data System (ADS)

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

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

2013-10-01

67

Acoustic dipole radiation based conductivity image reconstruction for magnetoacoustic tomography with magnetic induction  

NASA Astrophysics Data System (ADS)

Based on the acoustic dipole radiation theory, a tomograhic conductivity image reconstruction algorithm is developed for the magnetoacoustic tomography with magnetic induction (MAT-MI) in a cylindrical measurement configuration. It has been experimentally proved for a tissue-like phantom that not only the configuration but also the inner conductivity distribution can be reconstructed without any borderline stripe. Furthermore, the spatial resolution also can be improved without the limitation of acoustic vibration. The favorable results have provided solid verification for the feasibility of conductivity image reconstruction and suggested the potential applications of MAT-MI in the area of medical electrical impedance imaging.

Sun, Xiaodong; Zhang, Feng; Ma, Qingyu; Tu, Juan; Zhang, Dong

2012-01-01

68

Reconstructed imaging of acoustic cloak using time-lapse reversal method  

NASA Astrophysics Data System (ADS)

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.

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

2014-08-01

69

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

Microsoft Academic Search

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

James A. Simmons; Roger A. Stein

1980-01-01

70

A simple method for quantitative imaging of 2D acoustic fields using refracto-vibrometry  

NASA Astrophysics Data System (ADS)

This paper presents a simple 2D method for rapid time resolved quantitative imaging of acoustic waves using refracto-vibrometry. We present the theoretical background, the experimental method and reconstructions of acoustic reflection and interference. We investigate the applicability of the method, in particular the effect of sound radiator geometry. Finite element and experimental reconstructions of the sound fields are analysed. The spatial limitations and accuracy of the method are presented and discussed.

Malkin, Robert; Todd, Thomas; Robert, Daniel

2014-09-01

71

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

NASA Astrophysics Data System (ADS)

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

Kraeutner, Paul Hans

72

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

NASA Astrophysics Data System (ADS)

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

Yegireddi, Satyanarayana; Thomas, Nitheesh

2014-06-01

73

A surface acoustic wave /SAW/ charge transfer imager  

NASA Technical Reports Server (NTRS)

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

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

1981-01-01

74

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

NASA Astrophysics Data System (ADS)

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

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

2011-05-01

75

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

DOEpatents

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

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

2002-01-01

76

[Modulation of the functional activity of the acoustic and visual analyzers under conditions of listening to one's own EEG acoustic image of the temporal and occipital cortex areas].  

PubMed

Investigation into the functional activity of the acoustic and visual analyzer has been carried out before and after procedures of listening to one's own EEG of the temporal and occipital cortex areas. It has been shown, that there is a dependence of the dynamics of latent periods of sensomotor response to modality of stimuli and localization of source of the EEG acoustic image. After listening to acoustic image of the temporal EEG, a reduction of sensomotor reaction latency in the acoustic test has been observed. After listening to acoustic image of the occipital EEC, a reduction of sensomotor reaction latency in the visual test has been observed. In the control session after listening to A. Vivaldi's music, no significant shifts of sensomotor reaction latency have been observed. A conclusion has been made that, under conditions of local EEG-acoustic feedback, there is a selective elevation of functional activity of the brain areas used as the EEG-source for acoustic image forming. PMID:19323448

Konstantinov, K V; Trushina, V N; Iakovlev, N M; Klimenko, V M

2009-01-01

77

An acoustic charge transport imager for high definition television applications  

NASA Technical Reports Server (NTRS)

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

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

1992-01-01

78

Acoustic imaging of vapor bubbles through optically non-transparent media  

SciTech Connect

A preliminary investigation of the feasibility of acoustic imaging of vapor bubbles through optically nontransparent media is described. Measurements are reported showing the echo signals produced by air filled glass spheres of various sizes positioned in an aqueous medium as well as signals produced by actual vapor bubbles within a water filled steel pipe. In addition, the influence of the metallic wall thickness and material on the amplitude of the echo signals is investigated. Finally several examples are given of the imaging of spherical bubbles within metallic pipes using a simulated array of acoustic transducers mounted circumferentially around the pipe. The measurement procedures and a description of the measuring system are also given.

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

1983-10-01

79

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

NASA Astrophysics Data System (ADS)

In this work high frequency scanning acoustic microscopy was employed to nondestructively characterize subsurface defects in chromium containing DLC (Cr-DLC) coatings. Subsurface defects as small as one micron were successfully detected in a flat Cr-DLC coated steel coupon. Depth of the imaged subsurface defects was estimated using a simple geometrical acoustics model. The nature of the subsurface defects was investigated by using FIB/SEM technique. Curved Cr-DLC coated components including a roller and gear tooth were also imaged, and the encountered challenges were addressed.

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

2004-02-01

80

Observation, theory and simulation of anisotropy in oceanic ambient noise fields and its relevance to Acoustic Daylight imaging  

Microsoft Academic Search

Acoustic Daylight is a new technique for creating pictorial images of undersea objects from the acoustic illumination provided by the ambient noise field. As in conventional photography, the directionality of the illumination affects the contrast in the image through the shadows that are cast. Three aspects of the directionality, or anisotropy, of ambient noise in the ocean are discussed in

Michael J. Buckingham; John R. Potter

1994-01-01

81

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

E-print Network

. This phenomenon was called microwave auditory or MIA. MIA was used to quantify physical parameters in mediaMicrowave-induced acoustic imaging of biological tissues Lihong V. Wang, Xuemei Zhao, Haitao Sun tomographic imaging of biological tissues by use of microwave-induced acoustic signal. It was demonstrated

Wang, Lihong

82

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

E-print Network

Acoustic imaging of a duct spinning mode by the use of an in-duct circular microphone array Qingkai 2013) An imaging method of acoustic spinning modes propagating within a circular duct simply in control theory for ordinary differential equations. Spinning mode propagation, however, is formulated

Huang, Xun

83

Acoustic daylight imaging via spectral factorization: Helioseismology and reservoir monitoring  

Microsoft Academic Search

The acoustic time history of the sun' s surface is a stochastic t x y -cube of informa- tion. Helioseismologists cross-correlate these noise traces to produce impulse response seismograms, providing the proof of concept for a long-standing geophysical conjec- ture. We pack the x y -mesh of time series into a single super-long one-dimensional time series. We apply Kolmogoroff spectral

James Rickett; Jon Claerbout

1999-01-01

84

LOCAL STRAIN AND DAMAGE MEASUREMENTS ON A COMPOSITE WITH DIGITAL IMAGE CORRELATION AND ACOUSTIC EMISSION  

E-print Network

LOCAL STRAIN AND DAMAGE MEASUREMENTS ON A COMPOSITE WITH DIGITAL IMAGE CORRELATION AND ACOUSTIC of each part is essential. To obtain the stress/strain relations strain measurements are conducted be measured simultaneously. To measure strain many techniques can be used (extensometers, strain gauges

Boyer, Edmond

85

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

Microsoft Academic Search

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

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

2011-01-01

86

Acoustic investigation of microbubble response to medical imaging ultrasound pulses   

E-print Network

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

Thomas, David H.

2010-01-01

87

Method and system to synchronize acoustic therapy with ultrasound imaging  

NASA Technical Reports Server (NTRS)

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

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

2009-01-01

88

Investigation of an acoustical holography system for real-time imaging  

NASA Astrophysics Data System (ADS)

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

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

1998-07-01

89

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

NASA Astrophysics Data System (ADS)

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

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

2003-12-01

90

Numerical Simulation of Target Range Estimation Using Ambient Noise Imaging with Acoustic Lens  

NASA Astrophysics Data System (ADS)

In ambient noise imaging (ANI), each pixel of a target image is mapped by either monochrome or pseudo color to represent its acoustic intensity in each direction. This intensity is obtained by measuring the target object's reflecting or scattering wave, with ocean background noise serving as the sound source. In the case of using an acoustic lens, the ANI system creates a C-mode-like image, where receivers are arranged on a focal plane and each pixel's color corresponds to the intensity of each receiver output. There is no consideration for estimating a target range by this method, because it is impossible to measure the traveling time between a transducer and a target by a method like an active imaging sonar. In this study, we tried to estimate a target range using the ANI system with an acoustic lens. Here, we conducted a numerical simulation of sound propagation based on the principle of the time reversal mirror. First, instead of actual ocean measurements in the forward propagation, we calculated the scattering wave from a rigid target object in an acoustic noise field generated by a large number of point sources using the two-dimensional (2D) finite difference time domain (FDTD) method. The time series of the scattering wave converged by the lens was then recorded on each receiver. The sound pressure distribution assuming that the time-reversed wave of the scattering wave was reradiated from each receiver position was also calculated using the 2D FDTD method in the backward propagation. It was possible to estimate a target range using the ANI system with an acoustic lens, because the maximum position of the reradiated sound pressure field was close to the target position.

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

2010-07-01

91

Numerical Simulation of Target Range Estimation Using Ambient Noise Imaging with Acoustic Lens  

NASA Astrophysics Data System (ADS)

In ambient noise imaging (ANI), each pixel of a target image is mapped by either monochrome or pseudo color to represent its acoustic intensity in each direction. This intensity is obtained by measuring the target object’s reflecting or scattering wave, with ocean background noise serving as the sound source. In the case of using an acoustic lens, the ANI system creates a C-mode-like image, where receivers are arranged on a focal plane and each pixel’s color corresponds to the intensity of each receiver output. There is no consideration for estimating a target range by this method, because it is impossible to measure the traveling time between a transducer and a target by a method like an active imaging sonar. In this study, we tried to estimate a target range using the ANI system with an acoustic lens. Here, we conducted a numerical simulation of sound propagation based on the principle of the time reversal mirror. First, instead of actual ocean measurements in the forward propagation, we calculated the scattering wave from a rigid target object in an acoustic noise field generated by a large number of point sources using the two-dimensional (2D) finite difference time domain (FDTD) method. The time series of the scattering wave converged by the lens was then recorded on each receiver. The sound pressure distribution assuming that the time-reversed wave of the scattering wave was reradiated from each receiver position was also calculated using the 2D FDTD method in the backward propagation. It was possible to estimate a target range using the ANI system with an acoustic lens, because the maximum position of the reradiated sound pressure field was close to the target position.

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

2010-07-01

92

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

NASA Technical Reports Server (NTRS)

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

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

1999-01-01

93

Artifact trapping during time reversal photoacoustic imaging for acoustically heterogeneous media.  

PubMed

Several different reconstruction algorithms have been proposed for photoacoustic tomography, most of which presuppose that the acoustic properties of the medium are constant and homogeneous. In practice, there are often unknown spatial variations in the acoustic properties, and these algorithms give, at best, only approximate estimates of the true image. The question as to which approach is the most robust in these circumstances is therefore one of practical importance. Image reconstruction by "time reversal"-using a numerical propagation model with a time-varying boundary condition corresponding to the measured data in reversed temporal order-has been shown to be less restrictive in its assumptions than most, and therefore a good candidate for a general and practically useful algorithm. Here, it is shown that such reconstruction algorithms can "trap" time reversed scattered waves, leading to artifacts within the image region. Two ways to mitigate this effect are proposed. PMID:19887310

Cox, Benjamin T; Treeby, Bradley E

2010-02-01

94

Acoustic field enhancement and subwavelength imaging by coupling to slab waveguide modes  

NASA Astrophysics Data System (ADS)

We present a theoretical study on the amplification of evanescent sound waves produced by coupling to trapped modes hosted by a fluidic planar waveguide. Total internal reflection at interfaces of different refractive indexes can be frustrated by the introduction of a slow slab waveguide which is leading to a gigantic field enhancement, useful for sensitive transducers and acoustic shock lithotripsy. The mechanism behind the evanescent field coupling that is also known as tunnelling barrier penetration in quantum mechanics is here adopted for its use in an acoustic superlens. The higher spatial harmonics produced by a subwavelength object can couple to trapped modes of the slow waveguide and be reproduced as an image at a distant plane. We suggest a practical implementation of these ideas by means of a silicone rubber slab containing positive acoustic wave propagation parameters.

Christensen, J.; García de Abajo, F. J.

2010-10-01

95

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

SciTech Connect

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

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

2013-01-25

96

Acoustic sensor array for sonic imaging in air  

Microsoft Academic Search

Sonic imaging in air is a field of study with growing applications such as objects location, tracking and identification. It is also used in NDE applications to detect defects or hidden objects inside the structure. The objective of this work is to present a sonic system capable of locating and imaging objects in air with high quality and good resolution.

Marcos Turqueti; Vitaliy Kunin; Bill Cardoso; Jafar Saniie; Erdal Oruklu

2010-01-01

97

An acoustic charge transport imager for high definition television applications  

NASA Technical Reports Server (NTRS)

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

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

1993-01-01

98

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

E-print Network

A Multiview, Multimodal Fusion Framework for Classifying Small Marine Animals with an Opto-Acoustic] and marine animal tracking [6], or acoustic sensors for fish classifica- tion [7, 8, 9]. Advantages Imaging System Paul L. D. Roberts and Jules S. Jaffe Marine Physical Laboratory Scripps Institution

Jaffe, Jules

99

Methods And Systems For Using Reference Images In Acoustic Image Processing  

DOEpatents

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

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

2005-01-04

100

ACOUSTICAL IMAGING AND MECHANICAL PROPERTIES OF SOFT ROCK AND MARINE SEDIMENTS  

SciTech Connect

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

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

2001-01-31

101

Automated detection framework of the calcified plaque with acoustic shadowing in IVUS images.  

PubMed

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

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

2014-01-01

102

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

PubMed Central

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

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

2014-01-01

103

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

PubMed

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

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

2015-02-01

104

Near-Field Imaging with Sound: An Acoustic STM Model  

ERIC Educational Resources Information Center

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

Euler, Manfred

2012-01-01

105

Scanning Michelson interferometer for imaging surface acoustic wave f ields  

Microsoft Academic Search

25 nm p Hz, and it is capable of directly measuring SAW's with frequencies ranging from 0.5 MHz up to 1 GHz. The fast scheme used for locating the optimum operation point of the interferometer facilitates high measuring speeds, up to 50,000 pointsh. The measured field image has a lateral resolution of better than 1 mm. The fully optical noninvasive

J. V. Knuuttila; P. T. Tikka; M. M. Salomaa

2000-01-01

106

Acoustical standards in engineering acoustics  

NASA Astrophysics Data System (ADS)

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

Burkhard, Mahlon D.

2001-05-01

107

4F8 Image Coding Course 1 4F8 Image Coding Course  

E-print Network

. . . . . . . . . . . . . . . . . . . . . 27 3 The DCT and the JPEG Standard 33 3.1 The Discrete Cosine Transform (DCT) . . . . . . . . . . . . . . . . . . . . 33 3.2 Fast algorithms for the DCT . . . . . . . . . . . . . . . . . . . . . . . . . . 36 3.3 The 2-dimensional DCT . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 3.4 Quantisation of DCT

Kingsbury, Nick

108

Acoustic radiation force impulse imaging of mechanical stiffness propagation in myocardial tissue.  

PubMed

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

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

2012-07-01

109

Fish population dynamics revealed by instantaneous continental-shelf scale acoustic imaging  

NASA Astrophysics Data System (ADS)

Video images of fish population densities over vast areas of the New Jersey continental shelf have been produced from acoustic data collected on a long range bistatic sonar system during the Acoustic Clutter 2003 experiment. Areal fish population densities were obtained after correcting the acoustic data for two-way transmission loss modeled using the range-dependent parabolic equation, spatially varying beampattern of the array, source level and mean target strength per fish. The wide-area fish density images reveal the temporal evolution of fish school distributions, their migration, as well as shoal formation and fragmentation at 50 s interval. Time series of the fish population within various density thresholds were made over the period of a day in an area containing millions of fish that at some instances formed a massive shoal extending over 12 km. The analysis shows that fish population in the area can be decomposed into a stable ambient population from lower-fish-density regions and a time-varying population composed from higher-density regions. Estimates of the differential speed between population centers of various shoals show that the average speed is on the order of a slow-moving surface vessel or submarine.

Ratilal, Purnima; Symonds, Deanelle; Makris, Nicholas C.; Nero, Redwood

2005-04-01

110

ACOUSTICAL IMAGING AND MECHANICAL PROPERTIES OF SOFT ROCK AND MARINE SEDIMENTS  

SciTech Connect

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

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

2002-11-18

111

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

NASA Astrophysics Data System (ADS)

With increasing demand for in-vivo observation of living cells, microscope techniques that do not need staining become more and more important. In this talk we present a combined multi-photon-acoustic microscope with the possibility to measure synchronously properties addressed by ultrasound and two-photon fluorescence. Ultrasound probes the local mechanical properties of a cell, while the high resolution image of the two-photon fluorescence delivers insight in cell morphology and activity. In the acoustic part of the microscope an ultrasound wave, with a frequency of GHz, is focused by an acoustic sapphire lens and detected by a piezo electric transducer assembled to the lens. The achieved lateral resolution is in the range of 1?m. Contrast in the images arises mainly from the local absorption of sound in the cells, related to properties, such as mass density, stiffness and viscose damping. Additionally acoustic microscopy can access the cell shape and the state of the cell membrane as it is a intrinsic volume scanning technique.The optical part bases on the emission of fluorescent biomolecules naturally present in cells (e.g. NAD(P)H, protophorphyrin IX, lipofuscin, melanin). The nonlinear effect of two-photon absorption provides a high lateral and axial resolution without the need of confocal detection. In addition, in the near-IR cell damages are drastically reduced in comparison to direct excitation in the visible or UV. Both methods can be considered as minimal invasive, as they relay on intrinsic contrast mechanisms and dispense with the need of staining. First results on living cells are presented and discussed.

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

2007-02-01

112

ACOUSTICAL IMAGING AND MECHANICAL PROPERTIES OF SOFT ROCK AND MARINE SEDIMENTS  

SciTech Connect

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

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

2002-11-18

113

Acoustic Microscopy  

E-print Network

A. History: The acoustic microscope was developed as a tool for studying the internal microstructure of nontransparent solids or biological materials. In acoustic microscopy, a sample is imaged by ultrasound waves, and the contrast in reflection furnishes a map of the spatial distribution of the mechanical properties. Several books and handbook articles give detailed historical outlines. Briefly, the development of the first high-frequency scanning acoustic microscope was motivated by the idea of using an acoustic field to study the spatial variations of the elastic material properties with nearly optical resolution (The lateral resolution of SAM is dependent on the frequency of the acoustic waves and, at best, is about 0.75 microns). The first experiments date back to the 1940's when high-frequency acoustic images were obtained by the Leningrad

unknown authors

114

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

SciTech Connect

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

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

2002-12-12

115

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

NASA Astrophysics Data System (ADS)

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

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

1996-12-01

116

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

PubMed Central

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

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

2008-01-01

117

Temperature-dependent differences in the nonlinear acoustic behavior of ultrasound contrast agents revealed by high-speed imaging and bulk acoustics.  

PubMed

Previous work by the authors has established that increasing the temperature of the suspending liquid from 20°C to body temperature has a significant impact on the bulk acoustic properties and stability of an ultrasound contrast agent suspension (SonoVue, Bracco Suisse SA, Manno, Lugano, Switzerland). In this paper the influence of temperature on the nonlinear behavior of microbubbles is investigated, because this is one of the most important parameters in the context of diagnostic imaging. High-speed imaging showed that raising the temperature significantly influences the dynamic behavior of individual microbubbles. At body temperature, microbubbles exhibit greater radial excursion and oscillate less spherically, with a greater incidence of jetting and gas expulsion, and therefore collapse, than they do at room temperature. Bulk acoustics revealed an associated increase in the harmonic content of the scattered signals. These findings emphasize the importance of conducting laboratory studies at body temperature if the results are to be interpreted for in vivo applications. PMID:21741759

Mulvana, Helen; Stride, Eleanor; Tang, Mengxing; Hajnal, Jo V; Eckersley, Robert

2011-09-01

118

Evaluation of cervical cancer detection with acoustic radiation force impulse ultrasound imaging.  

PubMed

The aim of this study was to evaluate the application of acoustic radiation force impulse (ARFI) ultrasound imaging and its potential value in the characterization of cervical cancer. ARFI ultrasound imaging of the uterine cervix was performed in 58 patients with cervical cancer prior to surgery. The diagnosis of cervical cancer was confirmed by pathological results in each case. eSie Touch elastography imaging (EI), Virtual Touch tissue imaging (VTI) and Virtual Touch tissue quantification (VTQ; Siemens Medical Solutions, Mountain View, CA, USA) were used to qualitatively and quantitatively analyze the elasticity and hardness of lesions. For statistical analysis, the non-parametric Mann-Whitney U test and the Student's u test were used to compare the elastic parameters and the results. EI showed that, compared with the surrounding cervical tissue, 72.41% (42 of 58) of the malignant lesions showed 4th or 5th grade images and 27.59% (16 of 58) had 3rd grade images. The EI images showed a significant difference between the malignant lesions and the surrounding normal tissues (P<0.001). VTI showed that compared with the surrounding cervical tissue, 84.48% (49 of 58) of the malignant lesions were stiffer than the surrounding tissues and 15.52% (9 of 58) had black and white honeycomb-like images. The VTI images showed a significant difference between the malignant lesions and normal cervical tissues (P<0.001). The surrounding normal tissues had lower VTQ values, with a mean of 2.11±1.19 m/sec, while the VTQ values in malignant lesions were higher than the surrounding normal tissues (3.41±1.59 m/sec, P<0.001). ARFI ultrasound imaging of the uterine cervix may be an objective method for the assessment of soft tissues. It has high sensitivity and specificity in the evaluation of cervical cancer and therefore has good diagnostic value in clinical applications. PMID:23837060

Su, Yijin; DU, Lianfang; Wu, Ying; Zhang, Juan; Zhang, Xuemei; Jia, Xiao; Cai, Yingyu; Li, Yunhua; Zhao, Jing; Liu, Qian

2013-06-01

119

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

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

120

ACOUSTICAL IMAGING AND MECHANICAL PROPERTIES OF SOFT ROCK AND MARINE SEDIMENTS  

SciTech Connect

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

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

2001-04-01

121

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

SciTech Connect

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

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

2014-01-15

122

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

PubMed Central

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

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

2014-01-01

123

Application of pulse acoustic microscopy technique for 3D imaging bulk microstructure of carbon fiber-reinforced composites.  

PubMed

Impulse acoustic microscopy technique is applied for 3D imaging of bulk microstructure of composite materials. Short pulses of focused high-frequency ultrasound have been employed for layer-by-layer imaging of internal microstructure of carbon fiber-reinforced composite (CFRC) laminates. The method provides spatial resolution of 60 microm and in-depth resolution of 80 microm, approximately. Echo signals reflected from structural units--plies, fiber bundles; and microflaws form acoustic images of microstructure at different depth inside samples. The images make it possible to see ply arrays, packing of bundles in plies; binding material distribution over the specimen body. They reveal failure of interply adhesion, buckling of single plies and fiber bundles, internal defoliations and disbonds, voids in the specimen body. The series of successive images offer outstanding possibilities to reconstruct the bulk structure, to estimate local variations of properties, topological and geometrical characteristics of structural components. The imaging technique has been applied to study different types of fiber packing--unidirectional, cross-ply and woven laminates. Mechanisms of ultrasonic contrast for diverse elements in acoustic images of CFRC laminate bulk microstructure and structural defects are discussed. PMID:16876841

Liu, Songping; Guo, Enming; Levin, V M; Liu, Feifei; Petronyuk, Yu S; Zhang, Qianlin

2006-12-22

124

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

SciTech Connect

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

P Oshkai; M Geveci; D Rockwell; M Pollack

2004-05-24

125

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

NASA Astrophysics Data System (ADS)

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

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

2010-02-01

126

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

PubMed

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

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

2014-04-01

127

23 CFR 774.3 - Section 4(f) approvals.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Section 4(f) approvals. 774.3 Section 774.3 Highways...WATERFOWL REFUGES, AND HISTORIC SITES (SECTION 4(F)) § 774.3 Section 4(f) approvals. The Administration may not...

2010-04-01

128

77 FR 321 - Section 4(f) Policy Paper  

Federal Register 2010, 2011, 2012, 2013

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

2012-01-04

129

Acoustically Induced Spin-Orbit Interactions Revealed by Two-Dimensional Imaging of Spin Transport in GaAs  

NASA Astrophysics Data System (ADS)

Magneto-optic Kerr microscopy was employed to investigate the spin-orbit interactions of electrons traveling in semiconductor quantum wells using surface acoustic waves (SAWs). Two-dimensional images of the spin flow induced by SAWs exhibit anisotropic spin precession behaviors caused by the coexistence of different types of spin-orbit interactions. The dependence of spin-orbit effective magnetic fields on SAW intensity indicates the existence of acoustically controllable spin-orbit interactions resulting from the strain and Rashba contributions induced by the SAWs.

Sanada, H.; Sogawa, T.; Gotoh, H.; Onomitsu, K.; Kohda, M.; Nitta, J.; Santos, P. V.

2011-05-01

130

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

PubMed Central

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

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

2013-01-01

131

Spatially resolved acoustic spectroscopy for rapid imaging of material microstructure and grain orientation  

NASA Astrophysics Data System (ADS)

Measuring the grain structure of aerospace materials is very important to understand their mechanical properties and in-service performance. Spatially resolved acoustic spectroscopy is an acoustic technique utilizing surface acoustic waves to map the grain structure of a material. When combined with measurements in multiple acoustic propagation directions, the grain orientation can be obtained by fitting the velocity surface to a model. The new instrument presented here can take thousands of acoustic velocity measurements per second. The spatial and velocity resolution can be adjusted by simple modification to the system; this is discussed in detail by comparison of theoretical expectations with experimental data.

Smith, Richard J.; Li, Wenqi; Coulson, Jethro; Clark, Matt; Somekh, Michael G.; Sharples, Steve D.

2014-05-01

132

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

PubMed Central

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

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

2014-01-01

133

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

SciTech Connect

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

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

2011-06-23

134

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

SciTech Connect

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

Kuehn, Kerry, K.

2008-10-28

135

Predicting the acoustic response of a microbubble population for contrast imaging in medical ultrasound  

Microsoft Academic Search

Although the behavior of a bubble in an acoustic field has been studied extensively, few theoretical treatments to date have been applied to simulate the acoustic response of a real population of variably sized microbubbles in a finite-width sound beam. In this paper, we present a modified Trilling equation for single bubble dynamics that has been solved numerically for different

Chien Ting Chin; Peter N. Burns

2000-01-01

136

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

NASA Astrophysics Data System (ADS)

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.

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

2012-02-01

137

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

PubMed Central

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

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

2014-01-01

138

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

PubMed

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

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

2015-02-01

139

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

140

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

PubMed Central

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

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

2013-01-01

141

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

E-print Network

electromagnetic energy and subsequently emits acoustic waves through ther- moelastic expansion. The generated thermoacoustic waves are then collected by ultrasonic transducers to reconstruct microwave specific absorption were studied. A numerical model for calculating the propagation of ther- moacoustic waves through

Wang, Lihong

142

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

PubMed Central

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

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

2013-01-01

143

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

Microsoft Academic Search

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

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

1996-01-01

144

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

PubMed Central

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

Sharples, Joseph W.; Collison, David

2014-01-01

145

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

PubMed

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

Sharples, Joseph W; Collison, David

2014-02-01

146

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

PubMed

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 360 ms 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

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

2013-11-01

147

ACOUSTICAL IMAGING AND MECHANICAL PROPERTIES OF SOFT ROCK AND MARINE SEDIMENTS  

SciTech Connect

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

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

2001-07-01

148

23 CFR 774.3 - Section 4(f) approvals.  

Code of Federal Regulations, 2012 CFR

...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....

2012-04-01

149

23 CFR 774.3 - Section 4(f) approvals.  

Code of Federal Regulations, 2013 CFR

...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....

2013-04-01

150

23 CFR 774.3 - Section 4(f) approvals.  

...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....

2014-04-01

151

23 CFR 774.3 - Section 4(f) approvals.  

Code of Federal Regulations, 2011 CFR

...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....

2011-04-01

152

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

NASA Astrophysics Data System (ADS)

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

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

2009-08-01

153

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)

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.

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

2013-03-01

154

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

PubMed Central

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

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

2014-01-01

155

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

USGS Publications Warehouse

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

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

2002-01-01

156

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

SciTech Connect

Subbottom profiles and sidescan-sonar images collected on and around the Palos Verdes shelf show a surficial deposit interpreted to contain effluent from the White's Point diffusers, as well as showing several geologic features that affect the deposit's distribution. The effluent-affected deposit is visible in high-resolution subbottom profiles on the shelf and the adjacent San Pedro basin slope to water depths of 170 m. It has a maximum thickness of 75 cm and was mapped acoustically over an area of 10.8 km{sup 2}, which encompasses a volume of about 3.2 million m{sup 3}. The deposit's basal reflector is acoustically distinct over most of the mapped area, implying that the deposit has not been extensively mixed across its base, perhaps being relatively free of reworking since its initial deposition. Nearshore, the basal reflector is weak and fades away toward land, which could result from syndepositional intermixing of coarse native sediment (particularly from the Portuguese Bend landslide) with effluent in the high-energy nearshore zone, or postdepositionally by physical (wave) or biological mixing across the interface. The geometry of the deposit implies that effluent is dispersed primarily in a northwesterly and seaward direction from the diffusers. Dispersal across the shelf break is in some places strongly affected by topography, particularly by submarine canyons. The deposit overlies stratified and unstratified Quaternary sediment, up to 30 m thick, that in turn overlies the irregular erosional surface of deformed Miocene bedrock that crops out in places on the shelf and upper basin slope. The effluent-affected deposit rests on potentially unstable landslide deposits on the San Pedro basin slope. The acoustic profiles and side-scan images show evidence for active and inactive vents, probably of hot water and gas, some of which are within the boundary of the effluent-affected sediment deposit and could disrupt it if seepage occurs.

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

2001-12-01

157

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

NASA Astrophysics Data System (ADS)

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

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

2009-07-01

158

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

E-print Network

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

Grasland-Mongrain, Pol

2014-01-01

159

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

PubMed

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

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

2015-01-01

160

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

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

161

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

PubMed

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

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

2013-11-01

162

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

Federal Register 2010, 2011, 2012, 2013

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

2012-10-23

163

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

PubMed

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

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

2013-01-01

164

Characterization of acoustic imaging noise-induced hemodynamic response as a function of noise intensity in human auditory cortex fMRI at 3.0T  

Microsoft Academic Search

Acoustic imaging noise (AIN) associated with fast gradient switching during image acquisition is a confounding factor in auditory fMRI experiments. AIN interferes with the perception of desired stimuli as well as inducing hemodynamic responses that distort the responses to the desired stimuli. Moreover, non-linear behavior of the HDR to stimuli of varying intensities and durations make analysis of fMRI data

Minseok Kwon

2009-01-01

165

Calcified acoustic neuroma.  

PubMed

As our case indicates, it should be kept in mind that calcification, though unusual, does occur in acoustic neuromas. The statistical tendency of acoustic neuroma and meningioma to have different signal characteristics on magnetic resonance imaging may make MRI useful in increasing specificity in preoperative diagnosis. PMID:2788305

Beskin, R R; Eick, J J

1989-08-01

166

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

PubMed

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

Zhong, Siyang; Wei, Qingkai; Huang, Xun

2013-11-01

167

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

SciTech Connect

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

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

2008-07-29

168

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

PubMed

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 10(10) M(-1) cm(-1). This is comparable to plasmonic gold nano-particles, which have been studied as PA contrast agents. For the PNP larger than 100 nm, the enhancement of the PA signal was observed compared to the gold nano-particle with a similar absorption coefficient and size. In the case of the PNP, the heat by the light absorption is confined in the particle due to the low thermal diffusivity of polymer materials. We showed that the strong thermal confinement effect of PNP results in the enhancement of the efficiency of the PA signal generation and that the PA intensity can be enhanced by the increase of the Grüneisen parameter of the matrix polymer of PNP. The PA signal from the PNP of poly(methyl methacrylate) was 9-fold larger than that of gold nano-particles with the same absorption coefficient. We demonstrated that in the in vivo PA imaging the detection limit of PNP was of the order of 10(-13) M. The NIR absorbing PNP will be a promising candidate of a sensitive contrast agent for PA imaging. PMID:25407911

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

2015-01-01

169

Wavefront modulation and subwavelength diffractive acoustics with an acoustic metasurface  

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

170

Wavefront modulation and subwavelength diffractive acoustics with an acoustic metasurface.  

PubMed

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

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

2014-01-01

171

ACOUSTICAL IMAGING AND MECHANICAL PROPERTIES OF SOFT ROCK AND MARINE SEDIMENTS  

SciTech Connect

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

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

2002-04-30

172

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

NASA Astrophysics Data System (ADS)

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

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

2011-09-01

173

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

PubMed Central

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

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

2009-01-01

174

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

Microsoft Academic Search

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

Kuehn; Kerry

2008-01-01

175

Nonlinear acoustic enhancement in photoacoustic imaging with wideband absorptive nanoemulsion beads  

NASA Astrophysics Data System (ADS)

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.

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

176

The problematic C2H4+F2 reaction barrier  

NASA Astrophysics Data System (ADS)

The C2H4+F2 reaction is investigated through the most rigorous electronic structure methods currently feasible, using a focal point approach to converge toward the ab initio limit. Explicit computations were executed with basis sets as large as aug-cc-pV5Z and correlation treatments as extensive as coupled cluster through full triples with a perturbative inclusion of quadruple excitations [CCSDT(Q)]. Auxiliary core correlation, diagonal Born-Oppenheimer, and first-order relativistic corrections were included. All optimized geometries and vibrational frequencies were determined completely at the CCSD(T)/aug-cc-pVQZ level. The final C2H4+F2 reaction barrier from theory (8.0 kcal mol-1) is significantly higher than the recently reported experimental barrier (5.5±0.5 kcal mol-1). Our computations also yield a new enthalpy of formation of the fluoroethyl radical, ?fH298°(C2H4F)=-13.2±0.2 kcal mol-1, whose uncertainty is an order of magnitude less than previous experimental values.

Feng, Hao; Allen, Wesley D.

2010-03-01

177

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

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

178

Person-to-person distribution (up to 10 persons) by the author only. Not permitted for publication for institutional repositories or on personal Web sites. Aberration Correction with Low-Frequency Transmission for Medical Acoustic Imaging  

E-print Network

the distortion of the medium, where the main source of aberration is the human body wall. Many acoustic imaging-beam aberration correction;14­17) however, technological challenges still remain. A large proportion of aberration

Sato, Toru

179

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

Microsoft Academic Search

To visualize 3D inland geologic structure associated with active faulting, one uses high-cost multiple seismic reflection profiles. Here we fortunately face an unusual case: a large lake across one of the most active faults allows us to use acoustic exploration to visualize the subsurface deformation as the 3D high-resolution images. We investigated the Kamishiro fault, which is a northern part

T. Haraguchi; Y. Yoshinaga; S. Toda

2006-01-01

180

Experimental studies of the turbulence structures of impinging reacting jets using time-resolved particle image velocimetry visualisation, hot wire anemometry and acoustic signal processing  

Microsoft Academic Search

In this paper, the turbulence structures of premixed impinging jets are investigated by three different experimental techniques:\\u000a time-resolved particle image velocimetry (TPIV) visualisation, hot wire anemometry (HWA) and acoustic signal processing. The\\u000a focus is on the TPIV, with the other two techniques providing supplementary information. The 2-D velocities of the impinging\\u000a jets were obtained by TPIV. The contour maps of

Y. Zhang

2000-01-01

181

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

NASA Astrophysics Data System (ADS)

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

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

2011-07-01

182

Advances in Acoustic Microscopy (volume 2)  

Microsoft Academic Search

Acoustic methods for interior examination of materials have a well established role in medical imaging and non-destructive testing. Less well known is the field of acoustic microscopy where imaging is achieved on a similar scale to optical microscopy, but where contrast is provided through the elastic properties of the media rather than by reflection and scattering of light. Although acoustic

R M Langdon

1998-01-01

183

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

PubMed Central

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

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

2014-01-01

184

Flow sorting and sequencing meadow fescue chromosome 4F.  

PubMed

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

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

2013-11-01

185

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

E-print Network

and Dmitry Zotkin Perceptual Interfaces & Reality Lab., Computer Science & UMIACS, Univ. of Maryland, College Center in College Park, MD. Index Terms-- spherical microphone arrays, room acoustics, acoustical camera/clarity, warmth/brilliance, texture, blend, and ensemble. Most of these criteria are related to the room impulse

Zotkin, Dmitry N.

186

4f amplified in-line compressive holography.  

PubMed

Compressive holography is a combination of compressive sensing and holography. In this paper, an approach to expand the amplification ratio and enhance the axial resolution in in-line compressive holography is proposed. Firstly the basic principle of 4f amplified in-line compressive holography is described. Next the feasibility of reconstructing object and analysis of reconstruction quality is verified. Finally, both simulated and real experiments on multilayer objects with non-overlapping and overlapping patterns are demonstrated to validate the approach. PMID:25321197

Wu, Xiaoyan; Yu, Yingjie; Zhou, Wenjing; Asundi, Anand

2014-08-25

187

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

PubMed

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

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

2014-07-01

188

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

PubMed

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

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

2012-08-01

189

Kenyon College: Acoustics Instruments  

NSDL National Science Digital Library

This web page is an extensive collection of images and descriptions of historical instruments used in the teaching acoustics. Many of the items were used for demonstrations, labs, or other teaching purposes. This is part of a large collection of image covering all classical physics topics.

Greenslade Jr., Thomas

2011-04-09

190

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

NASA Astrophysics Data System (ADS)

Energies of 4f^N states relative to crystal band states were measured for rare-earth ions in the optical host materials LiYF4, Na0.4Y0.6F2.2, and LaF3 using x-ray photoemission spectroscopy. Spectra were modeled to determine the valence band maximum and 4f^ electron binding energies in each material. These results were combined with 4f^N to 4f^N-15d transition energies to determine 5d binding energies for the lowest levels of excited 4f^N-15d configurations. While 4f^N ground-state energies vary within several eV of the valence band maximum for different rare-earth ions in each host, the lowest 4f^N-15d states have similar energies and are several eV below the bottom of the conduction band. A simple model accurately described 4f^N and 4f^N-15d binding energies across the entire series of rare-earth ions. These results improve the understanding of optical materials for lasers, phosphors, and spectral hole burning applications for optical signal processing and data storage.

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

2005-03-01

191

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

PubMed Central

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

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

2014-01-01

192

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

PubMed Central

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

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

2013-01-01

193

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

SciTech Connect

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

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

1999-07-01

194

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

NASA Astrophysics Data System (ADS)

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

Chu, Zhigang; Yang, Yang

2014-10-01

195

Acoustic Source Localization Using the Acoustic ENSBox  

E-print Network

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

Grether, Gregory

196

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 ...

197

Acoustic emission linear pulse holography  

DOEpatents

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

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

1983-10-25

198

Acoustic sniper localization system  

NASA Astrophysics Data System (ADS)

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.

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

1997-02-01

199

Acoustic Seal  

NASA Technical Reports Server (NTRS)

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

Steinetz, Bruce M. (Inventor)

2006-01-01

200

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)

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.

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

2010-01-01

201

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

SciTech Connect

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

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

2014-09-01

202

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

PubMed

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

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

2014-02-01

203

Direct calculation of 4f(3)-4f(3) transition intensities in Nd(3+)-doped YPO(4) system involving explicit effects of 4f(2)5d configuration.  

PubMed

The effects of the 4f(2)5d configuration on the intraconfigurational [Formula: see text] electric dipole transitions of Nd(3+) doped YPO(4) are taken into account by a 'direct' calculation. A simple model is applied to analyze the opposite-parity 4f(2)5d configuration admixing into 4f(3) 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 4f(2)5d configuration and other opposite-parity states such as the 4f(2)n(')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 (2)G(9/2)(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 4f(N) configurations of trivalent lanthanide ions with more than two f-electrons. PMID:21817400

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

2009-03-01

204

4F2hc stabilizes GLUT1 protein and increases glucose transport activity.  

PubMed

Glucose transporter 1 (GLUT1) is widely distributed throughout various tissues and contributes to insulin-independent basal glucose uptake. Using a split-ubiquitin membrane yeast two-hybrid system, we newly identified 4F2 heavy chain (4F2hc) as a membrane protein interacting with GLUT1. Though 4F2hc reportedly forms heterodimeric complexes between amino acid transporters, such as LAT1 and LAT2, and regulates amino acid uptake, we investigated the effects of 4F2hc on GLUT1 expression and the associated glucose uptake. First, FLAG-tagged 4F2hc and hemagglutinin-tagged GLUT1 were overexpressed in human embryonic kidney 293 cells and their association was confirmed by coimmunoprecipitation. The green fluorescent protein-tagged 4F2hc and DsRed-tagged GLUT1 showed significant, but incomplete, colocalization at the plasma membrane. In addition, an endogenous association between GLUT1 and 4F2hc was demonstrated using mouse brain tissue and HeLa cells. Interestingly, overexpression of 4F2hc increased the amount of GLUT1 protein in HeLa and HepG2 cells with increased glucose uptake. In contrast, small interfering RNA (siRNA)-mediated 4F2hc gene suppression markedly reduced GLUT1 protein in both cell types, with reduced glucose uptake. While GLUT1 mRNA levels were not affected by overexpression or gene silencing of 4F2hc, GLUT1 degradation after the addition of cycloheximide was significantly suppressed by 4F2hc overexpression and increased by 4F2hc siRNA treatment. Taken together, these observations indicate that 4F2hc is likely to be involved in GLUT1 stabilization and to contribute to the regulation of not only amino acid but also glucose metabolism. PMID:21270293

Ohno, Haruya; Nakatsu, Yusuke; Sakoda, Hideyuki; Kushiyama, Akifumi; Ono, Hiraku; Fujishiro, Midori; Otani, Yuichiro; Okubo, Hirofumi; Yoneda, Masayasu; Fukushima, Toshiaki; Tsuchiya, Yoshihiro; Kamata, Hideaki; Nishimura, Fusanori; Kurihara, Hiroki; Katagiri, Hideki; Oka, Yoshitomo; Asano, Tomoichiro

2011-05-01

205

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

206

The 4 f5 d configuration and VUV absorption of Pr 3+ in YPO 4  

Microsoft Academic Search

Crystal field interaction of the 5d electron [HCF(5d)] and the Coulomb interaction between the 5d and the 4f electrons [HC(fd)] are the most important interactions in determining the structure of the 4f5d configuration of Pr3+ in solids. Energy levels of the 4f5d configuration in YPO4:Pr were calculated by diagonalizing the simplified Hamiltonian HCF(5d)+HC(fd). Coulomb exchange interaction compresses the extension of

Shihua Huang; Fangtian You; Chunxia Meng; Dawei Wang; Y. Tao; Guobin Zhang

2007-01-01

207

How the hydrogen bond in NH4F is revealed with Compton scattering  

NASA Astrophysics Data System (ADS)

In order to probe electron wave functions involved in the bonding of NH4F , we have performed Compton scattering experiments in an oriented single crystal and in a powder. Ab initio calculations of the Compton profiles for NH4F and NH4Cl are used to enlighten the nature of the bonds in the NH4F crystal. As a consequence, we are able to show significant charge transfer in the ammonium ion which is not observable using other methods. Our study provides a compelling proof for hydrogen bond formation in NH4F .

Barbiellini, B.; Bellin, Ch.; Loupias, G.; Buslaps, T.; Shukla, A.

2009-04-01

208

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

SciTech Connect

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

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

2009-08-19

209

Music Acoustics  

NSDL National Science Digital Library

This web site provides a series of tutorials and information pages on topics in musical acoustics. It is organized into sections on basic background information or more specific information on strings, woodwinds, brass instruments, percussion, voice acoustics, and more. The level of material ranges from basic concepts of sound level and frequency to details on sound production for researchers or musicians. The resources were developed as part of a collaborative research project involving physicists, musicians, and engineers. Example topics include: standing waves and harmonics, open vs. closed pipes, violin and guitar acoustics, and an introduction to voice acoustics. Concepts are reinforced with multiple diagrams and animations.

Wolfe, Joe

2009-04-27

210

Identification of an isozyme form of protein synthesis initiation factor 4F in plants.  

PubMed

We showed previously that wheat germ extracts contain two forms of protein synthesis initiation factor 4F that have very similar functional properties (Browning, K. S., Lax, S. R., and Ravel, J. M. (1987) J. Biol. Chem. 262, 11228-11232). One form, designated eIF-4F, is a complex containing two subunits, p220 and p26. The other form, designated eIF-(iso)4F, is a complex containing two subunits, p82 and p28, which are antigenically distinct from the subunits of eIF-4F. Both the p26 subunit of eIF-4F and the p28 subunit of eIF-(iso)4F are m7G cap-binding proteins. In this investigation, affinity-purified antibodies to the p220 and p26 subunits of wheat germ eIF-4F and to the p82 and p28 subunits of wheat germ eIF-(iso)4F were used to determine if isozyme forms of eIF-4F are present in maize and cauliflower. Extracts from wheat germ, maize root tips, and cauliflower inflorescences were partially purified by adsorption on m7GTP-Sepharose and elution with m7GTP (MGS eluate). Analysis by sodium dodecyl sulfate gel electrophoresis and immunoblotting with antibodies to the subunits of the wheat germ factors showed that the MGS eluate from maize contains polypeptides that react with antibodies to the p82 and p28 subunits of wheat eIF-(iso)4F, as well as polypeptides that react with antibodies to the p220 and p26 subunits of wheat eIF-4F. The MGS eluate from cauliflower also contains polypeptides that reacted with antibodies to the subunits of wheat eIF-(iso)4F. These results indicate that both maize and cauliflower contain the isozyme form of eIF-4F. In addition, it was found that the factors in the MGS eluate from maize support polypeptide synthesis in a system from wheat deficient in eIF-4F and eIF-(iso)4F, whereas the factors in the MGS eluate from cauliflower support polypeptide synthesis only to a small extent. PMID:1577779

Browning, K S; Webster, C; Roberts, J K; Ravel, J M

1992-05-15

211

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

PubMed

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

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

2014-01-01

212

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

NASA Astrophysics Data System (ADS)

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

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

2014-01-01

213

Acoustic-emission linear-pulse holography  

SciTech Connect

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

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

1982-06-01

214

Acoustic Monitoring  

NSDL National Science Digital Library

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

215

Classroom Acoustics  

MedlinePLUS

... desks or chairs. When sound lingers in a room there is more interference with speech. In a classroom it is important to have a short reverberation time. Who is affected by poor classroom acoustics? All children are affected by poor classroom acoustics, ...

216

d-Electron mediated 4 f 7- 4 f 7 exchange in Gd-rich compounds; spin density functional study of Gd 2Cl 3  

NASA Astrophysics Data System (ADS)

Spin-density functional theory (SDFT) calculations of the d- f exchange coupling for the pseudo-one-dimensional (pseudo-1-D) chain compound Gd 2Cl 3 has been carried out using the 1-D model, Gd 8Cl 12(OPH 3) 4, by considering seven variations in the ordering of the 4 f 7 moments. The calculations indicate that this semiconducting system should exhibit antiferromagnetic ordering of the 4 f 7 moments in a pattern consistent with published neutron diffraction data. An attempt to account for the calculated magnetic energies of spin patterns using an Ising model was unsuccessful, indicating that the latter model is inappropriate. The qualitative features can be interpreted using a perturbative molecular orbital model that focuses on the influence of the 4 f 7- d exchange interaction on the d-based molecular orbitals. Fundamental to the d-electron-mediated exchange mechanism is the intra-atomic 4 f 7- d exchange interaction. The essence of this interaction is present in the Gd atom [4 f 75d 16s 2] , which is computationally investigated within SDFT. In Gd 2Cl 3, the d-electron-mediated f- f exchange interaction was interpreted using basic perturbation theory. Computed density of states and spin polarization information was used to support the perturbation-theoretic analysis.

Roy, Lindsay; Hughbanks, Timothy

2003-12-01

217

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

NASA Astrophysics Data System (ADS)

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

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

2015-02-01

218

4F decreases IRF5 expression and activation in hearts of tight skin mice.  

PubMed

The apoAI mimetic 4F was designed to inhibit atherosclerosis by improving HDL. We reported that treating tight skin (Tsk(-/+)) mice, a model of systemic sclerosis (SSc), with 4F decreases inflammation and restores angiogenic potential in Tsk(-/+) hearts. Interferon regulating factor 5 (IRF5) is important in autoimmunity and apoptosis in immune cells. However, no studies were performed investigating IRF5 in myocardium. We hypothesize that 4F differentially modulates IRF5 expression and activation in Tsk(-/+) hearts. Posterior wall thickness was significantly increased in Tsk(-/+) compared to C57Bl/6J (control) and Tsk(-/+) mice with 4F treatment assessed by echoradiography highlighting reduction of fibrosis in 4F treated Tsk(-/+) mice. IRF5 in heart lysates from control and Tsk/+ with and without 4F treatment (sc, 1 mg/kg/d, 6-8 weeks) was determined. Phosphoserine, ubiquitin, ubiquitin K(63) on IRF5 were determined on immunoprecipitates of IRF5. Immunofluorescence and TUNEL assays in heart sections were used to determine positive nuclei for IRF5 and apoptosis, respectively. Fluorescence-labeled streptavidin (SA) was used to determine endothelial cell uptake of biotinylated 4F. SA-agarose pulldown and immunoblotting for IRF5 were used to determine 4F binding IRF5 in endothelial cell cytosolic fractions and to confirm biolayer interferometry studies. IRF5 levels in Tsk(-/+) hearts were similar to control. 4F treatments decrease IRF5 in Tsk(-/+) hearts and decrease phosphoserine and ubiquitin K(63) but increase total ubiquitin on IRF5 in Tsk(-/+) compared with levels on IRF5 in control hearts. 4F binds IRF5 by mechanisms favoring association over dissociation strong enough to pull down IRF5 from a mixture of endothelial cell cytosolic proteins. IRF5 positive nuclei and apoptotic cells in Tsk(-/+) hearts were increased compared with controls. 4F treatments decreased both measurements in Tsk(-/+) hearts. IRF5 activation in Tsk(-/+) hearts is increased. 4F treatments decrease IRF5 expression and activation in Tsk(-/+) hearts by a mechanism related to 4F's ability to bind IRF5. PMID:23251680

Xu, Hao; Krolikowski, John G; Jones, Deron W; Ge, Zhi-Dong; Pagel, Paul S; Pritchard, Kirkwood A; Weihrauch, Dorothée

2012-01-01

219

Acoustic measurement of the Deepwater Horizon Macondo well flow rate  

E-print Network

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

Camilli, Richard

220

Music Acoustics  

NSDL National Science Digital Library

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

221

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

PubMed

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. Copyright © 2014 John Wiley & Sons, Ltd. PMID:25204539

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

2014-09-01

222

Acoustic emission linear pulse holography  

DOEpatents

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

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

1985-01-01

223

Acoustic emission linear pulse holography  

SciTech Connect

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

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

1985-07-30

224

The sounds of nanoscience: acoustic STM analogues  

NASA Astrophysics Data System (ADS)

A hands-on model of scanning tunnelling microscopy (STM) is presented. It uses near-field imaging with sound and computer assisted visualization to create acoustic mappings of resonator arrangements. Due to the (partial) analogy of matter and sound waves the images closely resemble STM scans of atoms. Moreover, the method can be extended to build an acoustic analogue of a quantum corral. The acoustic models foster reflections about the nature of STM images and elucidate the productive tension of imaging and imagining matter at the nanoscale.

Euler, Manfred

2013-09-01

225

Acoustic trauma  

MedlinePLUS

Acoustic trauma is injury to the hearing mechanisms in the inner ear. It is due to very loud noise. ... of sensory hearing loss . Damage to the hearing mechanisms within the inner ear may be caused by: ...

226

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

Code of Federal Regulations, 2010 CFR

...OF THE PROVISIONS OF THE VOTING RIGHTS ACT REGARDING LANGUAGE MINORITY GROUPS Nature of Coverage § 55.8 Relationship between...requirements of section 4(f)(4) and section 203(c) regarding minority language material and assistance are essentially...

2010-07-01

227

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

Code of Federal Regulations, 2011 CFR

...OF THE PROVISIONS OF THE VOTING RIGHTS ACT REGARDING LANGUAGE MINORITY GROUPS Nature of Coverage § 55.8 Relationship between...requirements of section 4(f)(4) and section 203(c) regarding minority language material and assistance are essentially...

2011-07-01

228

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

PubMed

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

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

2014-06-01

229

HAER PA,35SCRAN,4F (sheet 1 of 1) Delaware, Lackawanna & ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

HAER PA,35-SCRAN,4-F- (sheet 1 of 1) - Delaware, Lackawanna & Western Railroad, Scranton Yards, Scrap Platform, 350 feet South of South Washington Avenue & River Street, Scranton, Lackawanna County, PA

230

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

PubMed Central

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

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

2014-01-01

231

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

PubMed

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

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

2015-02-01

232

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

Microsoft Academic Search

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

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

1990-01-01

233

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

Microsoft Academic Search

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

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

2008-01-01

234

Acoustic Inversion in Optoacoustic Tomography: A Review  

PubMed Central

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

Rosenthal, Amir; Ntziachristos, Vasilis; Razansky, Daniel

2013-01-01

235

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

PubMed

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

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

2014-04-01

236

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

E-print Network

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

Boyer, Edmond

237

Acoustic Characterization of Mesoscale Objects  

SciTech Connect

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

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

2007-03-13

238

Performance limitations in underwater acoustic telemetry  

Microsoft Academic Search

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

J. A. Catipovic

1990-01-01

239

Smart Cooling Technology Utilizing Acoustic Streaming  

Microsoft Academic Search

Acoustic streaming induced by longitudinal vibration at 30 kHz is visualized with particle imaging velocimetry (PIV). To gauge an increase in the velocity of air flow due to acoustic streaming, the velocity of air flow in a gap between the heat source and ultrasonic vibrator is measured using PIV. The ultrasonic wave propagating into air in the gap creates steady-state

Dong-Ryul Lee; Byoung-Gook Loh

2007-01-01

240

Calculation of the 4f1 ? 4f05d1 transitions in Ce3+-doped systems by Ligand Field Density Functional Theory  

NASA Astrophysics Data System (ADS)

We present a recipe for the calculation of the optical properties of Ce3+-doped systems. The model implies the use of ligand field phenomenology in conjunction with Density Functional Theory (DFT). The particular procedures enable the reliable prediction of the 4f1 ? 4f05d1 transitions in Cs2NaYCl6:Ce3+. The analysis of the doping of Ce3+ into the host is accomplished by band structure calculations. The calculated multiplet energy levels are in agreement with the experimental observation, the outlined treatment being, to the best of our knowledge, unprecedented clear and conclusive application of DFT for the rather complex problems of structure and spectroscopy of cerium-doped systems.

Ramanantoanina, Harry; Urland, Werner; García-Fuente, Amador; Cimpoesu, Fanica; Daul, Claude

2013-11-01

241

Excitation of dysprosium atom levels belonging to even 4f96s26p and 4f106p2 configurations  

NASA Astrophysics Data System (ADS)

Excitation of radiative transitions of dysprosium atoms from even levels belonging to 4 f 96 s 26 p and 4 f 106 p 2 configurations has been studied by experiment. Sixty-six excitation cross sections measured at an exciting electron energy of 30 eV. Four optical excitation functions recorded in the electron energy range of 0-200 eV. A classification based on known DyI energy levels proposed for several spectral lines. In most cases excitation cross-sections measured do not exceed 1 × 10-18 cm2 as the parity of upper levels studied in the present paper coincide with the parity of the DyI ground level which is the initial level in the excitation process.

Smirnov, Yuriy Mikhailovich

2015-01-01

242

Excitation of dysprosium atom levels belonging to even 4f96s26p and 4f106p2 configurations  

NASA Astrophysics Data System (ADS)

Excitation of radiative transitions of dysprosium atoms from even levels belonging to 4f96s26p and 4f106p2 configurations has been studied by experiment. Sixty-six excitation cross sections measured at an exciting electron energy of 30 eV. Four optical excitation functions recorded in the electron energy range of 0-200 eV. A classification based on known DyI energy levels proposed for several spectral lines. In most cases excitation cross-sections measured do not exceed 1 × 10-18 cm2 as the parity of upper levels studied in the present paper coincide with the parity of the DyI ground level which is the initial level in the excitation process.

Mikhailovich Smirnov, Yuriy

2015-01-01

243

Physical and Engineering Acoustics 17 uation,10,11  

E-print Network

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

244

Quantitative Thermo-acoustics and related problems Guillaume Bal  

E-print Network

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

Bal, Guillaume

245

Quantitative Thermo-acoustics and related problems Guillaume Bal  

E-print Network

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

Ren, Kui

246

Results of magnetic resonance imaging assessment, acoustic analysis, phonatory function and perceptual rating of glottic insufficiency before and after fat augmentation: correlated with subjective rating.  

PubMed

Autogenous fat augmentation has been proven effective in the treatment of glottic insufficiency (GI) using both subjective and objective methods of evaluation. However, no information is available in published research regarding the effectiveness and predictability of value parameters with regard to patients' perceptions and concerns. This article retrospectively examines the correlation between subjective and objective examinations and subjective ratings (SRs) in patients with presbylaryngis (n = 14) and sulcus vocalis (n = 2). Acoustic analysis, phonatory function, magnetic resonance imaging (MRI) assessment, and perceptual rating data were evaluated against SRs using pre- and postoperative test results in 16 patients. The mean time over which subjective and objective examinations were performed was 10 months. Twelve patients reported excellent results, while no change was observed in 4 patients. When compared against SR, the kappa value of jitter, shimmer, harmonic to noise ratio, phonation time, grade, roughness, breathiness, and MRI were 0.25, 0, -0.08, -0.11, -0.11, 0.18, 0, and 1, respectively. The agreement between the MRI and SR values was complete, and was the only relationship shown to be significant (p < 0.001). MRI assessment is an effective and reliable examination tool which can be considered for use in assessing the progress of the post-fat injection operation in GI patients during follow-up examinations. Furthermore, due to the excellent agreement between MRI assessment and the patients' subjective feelings, the SR value may serve as a good index of fat survival. PMID:12824728

Hsiung, Ming-Wang; Chen, Yen-Yu; Pai, Lu; Lin, Chao-Jung; Wang, Hsing-Won

2003-01-01

247

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

PubMed

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

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

2012-05-15

248

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

NASA Technical Reports Server (NTRS)

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

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

2009-01-01

249

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

NASA Technical Reports Server (NTRS)

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

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

2010-01-01

250

Visualization of protease activity in vivo using an activatable photo-acoustic imaging probe based on CuS nanoparticles.  

PubMed

Herein, we for the first time report a novel activatable photoacoustic (PA) imaging nano-probe for in vivo detection of cancer-related matrix metalloproteinases (MMPs). A black hole quencher 3 (BHQ3) which absorbs red light is conjugated to near-infrared (NIR)-absorbing copper sulfide (CuS) nanoparticles via a MMP-cleavable peptide linker. The obtained CuS-peptide-BHQ3 (CPQ) nano-probe exhibits two distinctive absorption peaks at 630 nm and 930 nm. Inside the tumor microenvironment where MMPs present, the MMP-sensitive peptide would be cleaved, releasing BHQ3 from the CuS nanoparticles, the former of which as a small molecule is then rapidly cleared out from the tumor, whereas the latter of which as large nanoparticles would retain inside the tumor for a much longer period of time. As the result, the PA signal at 680 nm which is contributed by BHQ3 would be quickly diminished while that at 930 nm would be largely retained. The PA signal ratio of 680 nm / 930 nm could thus serve as an in vivo indicator of MMPs activity inside the tumor. Our work presents a novel strategy of in vivo sensing of MMPs based on PA imaging, which should offer remarkably improved detection depth compared with traditional optical imaging techniques. PMID:24465271

Yang, Kai; Zhu, Lei; Nie, Liming; Sun, Xiaolian; Cheng, Liang; Wu, Chenxi; Niu, Gang; Chen, Xiaoyuan; Liu, Zhuang

2014-01-01

251

Visualization of Protease Activity In Vivo Using an Activatable Photo-Acoustic Imaging Probe Based on CuS Nanoparticles  

PubMed Central

Herein, we for the first time report a novel activatable photoacoustic (PA) imaging nano-probe for in vivo detection of cancer-related matrix metalloproteinases (MMPs). A black hole quencher 3 (BHQ3) which absorbs red light is conjugated to near-infrared (NIR)-absorbing copper sulfide (CuS) nanoparticles via a MMP-cleavable peptide linker. The obtained CuS-peptide-BHQ3 (CPQ) nano-probe exhibits two distinctive absorption peaks at 630 nm and 930 nm. Inside the tumor microenviorment where MMPs present, the MMP-sensitive peptide would be cleaved, releasing BHQ3 from the CuS nanoparticles, the former of which as a small molecule is then rapidly cleared out from the tumor, whereas the latter of which as large nanoparticles would retain inside the tumor for a much longer period of time. As the result, the PA signal at 680 nm which is contributed by BHQ3 would be quickly diminished while that at 930 nm would be largely retained. The PA signal ratio of 680 nm / 930 nm could thus serve as an in vivo indicator of MMPs activity inside the tumor. Our work presents a novel strategy of in vivo sensing of MMPs based on PA imaging, which should offer remarkably improved detection depth compared with traditional optical imaging techniques. PMID:24465271

Yang, Kai; Zhu, Lei; Nie, Liming; Sun, Xiaolian; Cheng, Liang; Wu, Chenxi; Niu, Gang; Chen, Xiaoyuan; Liu, Zhuang

2014-01-01

252

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

PubMed

Lanthanide tetrahalide molecules LnX4 (Ln = Ce, Pr, Tb; X = F, Cl, Br, I) have been investigated by density functional theory at the levels of the relativistic Zero Order Regular Approximation and the relativistic energy-consistent pseudopotentials, using frozen small- and medium-cores. The calculated bond lengths and vibrational frequencies are close to the experimental data. Our calculations indicate 4f shell contributions to bonding in LnX4, in particular for the early lanthanides, which show significant overlap between the Ln 4f-shell and the halogen np-shells. The 4f shells contribute to Ln-X bonding in LnX4 about one third more than in LnX3. PMID:25554160

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

2014-12-28

253

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

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

254

Acoustic transducer for acoustic microscopy  

DOEpatents

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

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

1990-01-01

255

Acoustic transducer for acoustic microscopy  

DOEpatents

A shear acoustic transducer-lens system is described in which a shear polarized piezoelectric material excites shear polarized waves at one end of a buffer rod having a lens at the other end which excites longitudinal waves in a coupling medium by mode conversion at selected locations on the lens. 9 figs.

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

1990-03-20

256

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

PubMed Central

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

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

2013-01-01

257

SF6 and C4F8 global kinetic models coupled to sheath models  

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

258

Spatiotemporally resolved granular acoustics  

NASA Astrophysics Data System (ADS)

Acoustic techniques provide a non-invasive method of characterizing granular material properties; however, there are many challenges in formulating accurate models of sound propagation due to the inherently heterogeneous nature of granular materials. In order to quantify acoustic responses in space and time, we perform experiments in a photoelastic granular material in which the internal stress pattern (in the form of force chains) is visible. We utilize two complementary methods, high-speed imaging and piezoelectric transduction, to provide particle-scale measurements of the amplitude of the acoustic wave. We observe that the average wave amplitude is largest within particles experiencing the largest forces. The force-dependence of this amplitude is in qualitative agreement with a simple Hertzian-like model for contact area. In addition, we investigate the power spectrum of the propagating signal using the piezoelectric sensors. For a Gaussian wave packet input, we observe a broad spectrum of transmitted frequencies below the driving frequency, and we quantify the characteristic frequencies and corresponding length scales of our material as the system pressure is varied.

Owens, Eli; Daniels, Karen

2011-03-01

259

Air-coupled acoustic thermography for in-situ evaluation  

NASA Technical Reports Server (NTRS)

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

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

2010-01-01

260

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

Code of Federal Regulations, 2010 CFR

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

2010-10-01

261

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

Code of Federal Regulations, 2010 CFR

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

2010-10-01

262

Energy position of 4f levels in rare-earth metals  

Microsoft Academic Search

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

Börje Johansson

1979-01-01

263

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

E-print Network

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

Avraham, Karen

264

Imaging transverse isotropic properties of muscle by monitoring acoustic radiation force induced shear waves using a 2-D matrix ultrasound array.  

PubMed

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

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

2013-09-01

265

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

PubMed Central

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

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

2013-01-01

266

The use of acoustic imaging to reveal fossil fluvial systems—a case study from the southwestern Sea of Galilee  

NASA Astrophysics Data System (ADS)

The analysis of reflected, high-resolution seismic data shows a distinct separation of regions with good and poor seismic penetration. Additional analysis of core data revealed good correlation between grain size and seismic penetration. As a case study, a shallow geophysical survey using a Chirp profiler was conducted in the southwestern part of the Sea of Galilee. By correlating the seismic and core data we found that areas with good seismic penetration represent coarse clastics, while poor seismic penetration is related to fine clays. New detailed bathymetric mapping and bottom morphology images combined with the penetration characteristics of the Chirp signal reveal a large alluvial fan consisting mainly of coarse material (sand to pebbles). A fine-grained band of mostly clay-size material, associated with an asymmetric bathymetric channel, continues the trend of the old entrance of the Yavniel Creek into the Sea of Galilee. We interpret the fine-clay stripe to be a low energy streambed of the Yavniel Creek. The clear relations between the reflected Chirp signal and the grain size of the water-bottom sediments suggests that this type of survey can be used to characterize depositional environments.

Reshef, Moshe; Ben-Avraham, Zvi; Tibor, Gideon; Marco, Shmuel

2007-01-01

267

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

NASA Astrophysics Data System (ADS)

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

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

2011-03-01

268

Sudden hearing loss in acoustic neuroma patients.  

PubMed

Patients with acoustic neuroma may have sudden sensorineural hearing loss. Most patients with sudden hearing loss seek medical attention promptly, but the diagnosis of an acoustic neuroma may be delayed for months or years because sudden hearing loss is an unusual initial symptom of an acoustic neuroma. In a retrospective review of 836 cases of sudden hearing loss, we found 13 patients with acoustic neuromas. The prevalence of acoustic neuromas for those screened with auditory brain stem response or magnetic resonance imaging was 2.5%. In addition to these 13 patients, 79 acoustic neuroma patients treated in our clinic had well-documented sudden hearing loss as the initial symptom. Hearing loss in these 92 patients ranged from mild to profound. Associated symptoms of pain, facial paresthesia, or unilateral tinnitus preceding the sudden hearing loss were suggestive of an acoustic neuroma, as was a midfrequency (U-shaped) hearing loss. A history of other diseases or events that might explain the sudden hearing loss, a normal electronystagmogram, or recovery of hearing does not eliminate the possibility of a tumor. Because there are no clinical findings that clearly distinguish those patients with acoustic neuromas from other patients with sudden hearing loss, we recommend either an evaluation with auditory brain stem response or gadolinium-enhanced magnetic resonance imaging for any patient with sudden hearing loss. PMID:7603717

Saunders, J E; Luxford, W M; Devgan, K K; Fetterman, B L

1995-07-01

269

LETTER TO THE EDITOR: Energy levels of 4f3 in the Nd3+ free ion from emission spectra  

Microsoft Academic Search

The emission spectrum of neodymium produced by vacuum spark sources was observed in the vacuum ultraviolet on two normal-incidence spectrographs. In an initial result, more than 550 lines have been identified as transitions from 85 4f25d levels to 37 levels of the 4f3 ground configuration in the free ion Nd3+. The levels 4f34F3\\/2 and 4I11\\/2, responsible for the well-known 1064

Jean-François Wyart; Ali Meftah; Annik Bachelier; Jocelyne Sinzelle; Wan-Ü. Lydia Tchang-Brillet; Norbert Champion; Nissan Spector; Jack Sugar

2006-01-01

270

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

E-print Network

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

Truszczynski, Miroslaw

271

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

E-print Network

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

Uçar, Bora

272

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

PubMed

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

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

2014-11-14

273

The 4F2hc\\/LAT1 complex transports l-DOPA across the blood–brain barrier  

Microsoft Academic Search

l-DOPA is transported across the blood–brain barrier (BBB) by an amino acid transporter, system L. Recently, it has been demonstrated that system L consists of two subunits, 4F2hc and either LAT1 or LAT2. 4F2hc\\/LAT1 and 4F2hc\\/LAT2 show different transport characteristics, while their distribution in the brain has not been determined. To clarify whether 4F2hc\\/LAT1 participates in l-DOPA transport across the

Takashi Kageyama; Masaru Nakamura; Akinori Matsuo; Yasuomi Yamasaki; Yoshinobu Takakura; Mitsuru Hashida; Yoshikatsu Kanai; Mikihiko Naito; Takashi Tsuruo; Nagahiro Minato; Shun Shimohama

2000-01-01

274

Characterization of Core Samples from a Hardened Crust Layer in Tank 4F  

SciTech Connect

Waste removal operations in Tank 4F are scheduled to begin in late 2005 to provide material for Sludge Batch 5. Mining/probing operations to support installation of submersible mixer pumps encountered a hard layer of material at {approx}45'' to 50'' from the bottom of the tank. Attempts at penetrating the hard layer using a manual mining tool in several different risers were not successful. A core-sampling tool was used to obtain samples of the hard crust layer in Tank 4F for characterization. Three 12'' core samples and a dip sample of the supernate near the surface of the hard layer were sent to Savannah River National Laboratory (SRNL) for characterization. X-ray Diffraction (XRD) results for the crystalline solids from both sample FTF-434 and FTF-435 identifies the major component of both samples as Burkeite (Na{sub 6}(CO{sub 3})(SO{sub 4}){sub 2}). All of the other data collected on the crystalline solids from the Tank 4F core samples support this conclusion. The conditions in Tank 4F for the last twenty years have been ideal for Burkeite formation. The tank has been largely undisturbed with a tank temperature consistently above 30 C, a carbonate to sulfate molar ratio in the supernate conducive to Burkeite formation, and slow evaporation of the supernate phase. Thermodynamic modeling and the results of a Burkeite solubility test confirm that a ratio of 1:1:12 for the volumes of Burkeite solids, supernate, and inhibited water will dissolve all of the Burkeite. These ratios could be used to remove the 6'' layer of Burkeite from Tank 4F with no mixing. However, the thermodynamic modeling and the solubility test neglect the sludge layer beneath the Burkeite crust in Tank 4F. Settled sludge in Savannah River Site (SRS) high-level waste tanks usually contains greater than 75% interstitial supernate by volume. If the supernate in the sludge layer should mix into the solution used to dissolve the Burkeite, significantly more inhibited water would be needed to dissolve the Burkeite layer. Additionally, the average thickness of the Burkeite layer across the diameter of the tank may be thicker or thinner than the 6'' assumed for modeling purposes. The 6'' thickness assumed for the Burkeite layer was based on the 6'' plug of solids found in one core sample. An average thickness greater than 6'' would increase the amount of water needed to dissolve the Burkeite.

Hay, M. L.

2005-09-28

275

A novel interaction of Cap-binding protein complexes eukaryotic initiation factor (eIF) 4F and eIF(iso)4F with a region in the 3'-untranslated region of satellite tobacco necrosis virus.  

PubMed

Satellite tobacco necrosis virus (STNV) RNA is naturally uncapped at its 5' end and lacks polyadenylation at its 3' end. Despite lacking these two hallmarks of eukaryotic mRNAs, STNV-1 RNA is translated very efficiently. A approximately 130-nucleotide translational enhancer (TED), located 3' to the termination codon, is necessary for efficient cap-independent translation of STNV-1 RNA. The STNV-1 TED RNA fragment binds to the eukaryotic cap-binding complexes, initiation factor (eIF) 4F and eIF(iso)4F, as measured by nitrocellulose binding and fluorescence titration. STNV-1 TED is a potent inhibitor of in vitro translation when added in trans. This inhibition is reversed by the addition of eIF4F or eIF(iso)4F, and the subunits of eIF4F and eIF(iso)4F cross-link to STNV-1 TED, providing additional evidence that these factors interact directly with STNV-1 TED. Deletion mutagenesis of the STNV-1 TED indicates that a minimal region of approximately 100 nucleotides is necessary to promote cap-independent translation primarily through interaction with the cap binding subunits (eIF4E or eIF(iso)4E) of eIF4F or eIF(iso)4F. PMID:14729906

Gazo, Brandy M; Murphy, Patricia; Gatchel, Jennifer R; Browning, Karen S

2004-04-01

276

Thermodynamic Properties of 4f- and 5f-SHELL Metals at Finite Temperatures:  

NASA Astrophysics Data System (ADS)

The thermodynamic properties of 4f- and 5f-shell metals have been studied at high temperatures using mean-field potential approach. The MFP seen by the lattice ion is constructed in terms of the total energy-volume relation using local pseudopotentials due to Pandya et al. [Physica B 307, 138 (2001)]. We have calculated static compression, shock-wave compression, volume thermal expansion, isothermal and adiabatic bulk moduli (BT and BS), specific heats (CV and CP), thermodynamic Grüneisen parameter (?th), anharmonic contribution to the specific heat and temperature along shock Hugoniot for 4f (?-Ce)- and 5f (fcc-Th)-shell metals. The results are well compared with the other theoretical and experimental findings, which ensure the use of pseudopotentials for studying thermodynamic properties at higher temperatures in case of lanthanides and actinides.

Bhatt, N. K.; Vyas, P. R.; Jani, A. R.; Gohel, V. B.

277

Strong hybridization of 4f states of heavy rare earths in intermetallic compounds  

NASA Astrophysics Data System (ADS)

Strong hybridization between 4f states of heavy rare earths (RE’s) and valence states was found in TbRh, TbPd, and DyPd. The resonant photoemission (PE) spectra taken in the region of the RE 4d?4f excitation threshold reveal splittings of the Tb 8S7/2 and Dy 7F6 components of the PE final-state multiplets if they overlap in energy the transition-metal 4d-derived valence bands of the compounds. The phenomenon is described quantitatively in the framework of the single-impurity Anderson model applied usually for the description of Ce systems. The reported results are of high importance for understanding electronic properties of heavy lanthanide systems including magnetic materials relevant for technological applications.

Molodtsov, S. L.; Kucherenko, Yu.; Vyalikh, D. V.; Behr, G.; Starodubov, A.; Laubschat, C.

2003-11-01

278

Identification of a new P450 subfamily, CYP4F1, expressed in rat hepatic tumors.  

PubMed

The expression of the rat cytochrome P450 CYP4 family was studied in hepatic tumors. In most of the primary and transplantable hepatic tumors studied, lauric acid omega-hydroxylase activity associated with the CYP4A subfamily enzymes decreased. The expression of CYP4A proteins and mRNAs in these tumors as assessed by Western and Northern blot was undetectable. However, while RNA analysis revealed the absence of 4A1, 4A2, and 4A3 mRNAs, the expression of CYP4 gene(s) was detected. A Uni-ZAP cDNA library was constructed from a 2-acetylaminofluorene-induced transplantable rat hepatic tumor and screened with a CYP4 family probe. A full-length sequenced cDNA of 1977 bp isolated contained a 23-bp 5' untranslated region, a 1572-bp open reading frame, and a 382-bp 3' untranslated region. This cDNA sequence deduced amino acid sequence encodes a P450 protein having a conserved region of the CYP4 family exhibiting 44-45% amino acid identity to rat CYP4A subfamily members, 43% to human CYP4B1, 35 and 32% to insect CYP4C1 and CYP4D1, respectively. This new P450 was thus named CYP4F1. RNA blot analysis with CYP4F1 cDNA and CYP4F1-specific oligonucleotide probes revealed the expression of CYP4F1 in all tumors. This is the first example of a P450 constitutively expressed in rat hepatomas at levels exceeding those in the parental liver tissue. These results suggest that there is differential regulation of CYP4 genes during hepatic carcinogenesis. PMID:8424651

Chen, L; Hardwick, J P

1993-01-01

279

Measuring acoustic energy density in microchannel acoustophoresis using a simple and rapid light-intensity method{  

E-print Network

Measuring acoustic energy density in microchannel acoustophoresis using a simple and rapid light the acoustic energy density in microchannel acoustophoresis based on light-intensity measurements image velocimetry for quantifying acoustophoretic performance in microchannels. I. Introduction

280

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

NASA Astrophysics Data System (ADS)

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

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

2012-07-01

281

The mouse chromosome 7 distal imprinting domain maps to G-bands F4/F5.  

PubMed

Mouse Chromosome (Chr) 7 distal to band F3 on the physical map is known to be subject to imprinting, maternal duplication (MatDp) of the region leading to a late embryonic lethality, while paternal duplication (PatDp) causes death in utero before 11.5 dpc. Using a new mouse reciprocal translocation T(7;11)65H to produce MatDp for distal Chr 7, we have mapped the region subject to imprinting more precisely to bands 7F4/F5 on the cytogenetic map. Fluorescence in situ hybridization (FISH) studies on mitotic and meiotic chromosomes of a T65H heterozygote show that the imprinted gene Igf2 is located in the same region. This was confirmed by the finding that embryos with MatDp of bands 7F4/F5 did not express Igf2. We suggest that other members of the imprinted domain containing Igf2, namely Mash2, H19, Ins2, and p57(K1P2), are also located in 7F4/F5 and that some or all of these genes may be responsible for the two imprinting lethalities seen with MatDp and PatDp for this region. PMID:9096101

Beechey, C V; Ball, S T; Townsend, K M; Jones, J

1997-04-01

282

Acoustic transducer  

DOEpatents

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

Drumheller, Douglas S. (Cedar Crest, NM)

2000-01-01

283

Acoustic cryocooler  

DOEpatents

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

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

1990-01-01

284

The use of measured acoustic speed distributions in reflection ultrasound CT  

Microsoft Academic Search

Brief details have been given of an ultrasound CT system based on linear arrays which can be used to generate both reflection UCT images and acoustic speed images of a suitable target section. The acoustic speed images have been shown to be of sufficient quality to provide high registration accuracy in the equivalent reflection images. The quality of the reflection

J. R. Jago; T. A. Whittingham

1992-01-01

285

Broadband acoustic quantification of stratified turbulence.  

PubMed

High-frequency broadband acoustic scattering techniques have enabled the remote, high-resolution imaging and quantification of highly salt-stratified turbulence in an estuary. Turbulent salinity spectra in the stratified shear layer have been measured acoustically and by in situ turbulence sensors. The acoustic frequencies used span 120-600 kHz, which, for the highly stratified and dynamic estuarine environment, correspond to wavenumbers in the viscous-convective subrange (500-2500 m(-1)). The acoustically measured spectral levels are in close agreement with spectral levels measured with closely co-located micro-conductivity probes. The acoustically measured spectral shapes allow discrimination between scattering dominated by turbulent salinity microstructure and suspended sediments or swim-bladdered fish, the two primary sources of scattering observed in the estuary in addition to turbulent salinity microstructure. The direct comparison of salinity spectra inferred acoustically and by the in situ turbulence sensors provides a test of both the acoustic scattering model and the quantitative skill of acoustical remote sensing of turbulence dissipation in a strongly sheared and salt-stratified estuary. PMID:23862783

Lavery, Andone C; Geyer, W Rockwell; Scully, Malcolm E

2013-07-01

286

Acoustic impedance microscopy for biological tissue characterization.  

PubMed

A new method for two-dimensional acoustic impedance imaging for biological tissue characterization with micro-scale resolution was proposed. A biological tissue was placed on a plastic substrate with a thickness of 0.5mm. A focused acoustic pulse with a wide frequency band was irradiated from the "rear side" of the substrate. In order to generate the acoustic wave, an electric pulse with two nanoseconds in width was applied to a PVDF-TrFE type transducer. The component of echo intensity at an appropriate frequency was extracted from the signal received at the same transducer, by performing a time-frequency domain analysis. The spectrum intensity was interpreted into local acoustic impedance of the target tissue. The acoustic impedance of the substrate was carefully assessed prior to the measurement, since it strongly affects the echo intensity. In addition, a calibration was performed using a reference material of which acoustic impedance was known. The reference material was attached on the same substrate at different position in the field of view. An acoustic impedance microscopy with 200×200 pixels, its typical field of view being 2×2 mm, was obtained by scanning the transducer. The development of parallel fiber in cerebella cultures was clearly observed as the contrast in acoustic impedance, without staining the specimen. The technique is believed to be a powerful tool for biological tissue characterization, as no staining nor slicing is required. PMID:24852259

Kobayashi, Kazuto; Yoshida, Sachiko; Saijo, Yoshifumi; Hozumi, Naohiro

2014-09-01

287

Advanced fiber-optic acoustic sensors  

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

288

Acoustic microscopy in the food industry  

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

289

The Sounds of Nanoscience: Acoustic STM Analogues  

ERIC Educational Resources Information Center

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

Euler, Manfred

2013-01-01

290

Differential phase acoustic microscope for micro-NDE  

NASA Technical Reports Server (NTRS)

A differential phase scanning acoustic microscope (DP-SAM) was developed, fabricated, and tested in this project. This includes the acoustic lens and transducers, driving and receiving electronics, scanning stage, scanning software, and display software. This DP-SAM can produce mechanically raster-scanned acoustic microscopic images of differential phase, differential amplitude, or amplitude of the time gated returned echoes of the samples. The differential phase and differential amplitude images provide better image contrast over the conventional amplitude images. A specially designed miniature dual beam lens was used to form two foci to obtain the differential phase and amplitude information of the echoes. High image resolution (1 micron) was achieved by applying high frequency (around 1 GHz) acoustic signals to the samples and placing two foci close to each other (1 micron). Tone burst was used in this system to obtain a good estimation of the phase differences between echoes from the two adjacent foci. The system can also be used to extract the V(z) acoustic signature. Since two acoustic beams and four receiving modes are available, there are 12 possible combinations to produce an image or a V(z) scan. This provides a unique feature of this system that none of the existing acoustic microscopic systems can provide for the micro-nondestructive evaluation applications. The entire system, including the lens, electronics, and scanning control software, has made a competitive industrial product for nondestructive material inspection and evaluation and has attracted interest from existing acoustic microscope manufacturers.

Waters, David D.; Pusateri, T. L.; Huang, S. R.

1992-01-01

291

Design and Experimental Applications of Acoustic Metamaterials  

NASA Astrophysics Data System (ADS)

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

Zigoneanu, Lucian

292

MINIMUM RISK ACOUSTIC CLUSTERING FOR MULTILINGUAL ACOUSTIC MODEL COMBINATION  

E-print Network

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

Byrne, William

293

Acoustic Propagation Considerations for Underwater Acoustic Communications Network Development  

E-print Network

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

Zhou, Shengli

294

Broadband enhanced transmission of acoustic waves through serrated metal gratings  

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

295

Red nucleus and rubrospinal tract disorganization in the absence of Pou4f1  

PubMed Central

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

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

2015-01-01

296

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

SciTech Connect

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

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

1996-05-01

297

C4F8O Pressurized Gas System for the Vhmpid R&d Studies  

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

298

Acoustic Simulation COMP 768 Presentation  

E-print Network

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

North Carolina at Chapel Hill, University of

299

Acoustic Neuroma Educational Video  

MedlinePLUS Videos and Cool Tools

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

300

Symptoms of Acoustic Neuroma  

MedlinePLUS

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

301

Acoustic Based Sketch Recognition  

E-print Network

investigate this new area, which we call acoustic based sketch recognition, and evaluate the possibilities of using it as a new interaction technique. We focus specifically on building a recognition engine for acoustic sketch recognition. We first propose a...

Li, Wenzhe

2012-10-19

302

Acoustic emission frequency discrimination  

NASA Technical Reports Server (NTRS)

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

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

1988-01-01

303

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

NASA Technical Reports Server (NTRS)

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

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

1996-01-01

304

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

305

Monolacunary Keggin polyoxometalates connected to ten 4d or 4f metal atoms.  

PubMed

The rational self-assembly of mono-lacunary Keggin clusters with 4d and 4f metal salts via a conventional method has yielded two novel polyoxometalate-based 4d-4f heterometallic compounds containing lacunary Keggin anions connected to ten metal atoms: {[Ag{Ag2(H2O)4}{Ln(H2O)6}2H ? {SiW11Ln(H2O)4O39}2]·nH2O (Ln = Ce and n = 7 for 1, Ln = Pr and n = 3 for 2). Their structures were determined by single crystal X-ray diffraction analyses and further characterized by elemental analyses, IR spectra, and thermogravimetric (TG) analyses. A structural feature in 1 and 2 is that each [SiW11O39](8-) cluster (SiW11) is connected to ten metals (five Ag(+) and five Ln(3+) cations), representing the highest number of connected metal atoms to any mono-lacunary Keggin anion to date. This large connectivity leads to a structure with a purely inorganic 3D framework with two kinds of channels along the [100] and [010] directions. The magnetic properties of both compounds show the expected magnetic moments (0.8 and 1.6 amu K mol(-1) per Ce(3+) and Pr(3+) ion, respectively) and confirm the presence of isolated Ce(3+) and Pr(3+) ions. PMID:24067933

Pang, Haijun; Gómez-García, Carlos J; Peng, Jun; Ma, Huiyuan; Zhang, Chunjing; Wu, Qingyin

2013-12-21

306

4f hybridization effect on the magnetism of Nd2PdSi3  

NASA Astrophysics Data System (ADS)

Among the members of the series R2PdSi3 (R = rare earth), the magnetic behavior of the Nd compound is interesting in some respects. This compound is considered to order ferromagnetically (<16 K), unlike other members of this series, which order antiferromagnetically. In addition, the magnetic ordering temperature (To) is significantly enhanced with respect to the de Gennes-scaled value. To understand the magnetism of this compound better, we have investigated the magnetic behavior in detail (and under external pressure) and examined its solid solutions based on substitutions at Nd and at Si sites, viz., on the series, Nd2-x(Y, La)xPdSi3-yGey (x, y = 0.2, 0.4, 0.8, and 1.2) by bulk measurements. The results overall establish that Nd2PdSi3 orders ferromagnetically below 16 K but an antiferromagnetic (AFM) component seems to set in at very low temperatures. However, there is significant suppression of To for Y and Ge substitutions compared to the La substitution for a given magnitude of unit cell volume change, qualitatively correlating with the separation between the layers of Nd and Pd-Si(Ge). On the basis of this observation, we conclude that 4f(Nd) hybridization plays a major role on the magnetism of the former solid solutions. To our knowledge, this work serves as a rare demonstration of the 4f hybridization effects on the magnetism of a Nd-based intermetallic compound.

Mukherjee, K.; Basu, Tathamay; Iyer, Kartik K.; Sampathkumaran, E. V.

2011-11-01

307

Acoustics and Vibration Animations  

NSDL National Science Digital Library

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

Russell, Daniel

308

Acoustic Heating Peter Ulmschneider  

E-print Network

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

Ulmschneider, Peter

309

Shallow water acoustic networks  

Microsoft Academic Search

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

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

2001-01-01

310

Underwater Laser Plasma Acoustic Source Directivity and Frequency Control Demonstration  

Microsoft Academic Search

A remote underwater laser acoustic source is under development at NRL. Sound is generated by intense laser pulses propagating through air and water, followed by underwater optical compression and laser-induced breakdown (LIB). Such an acoustic source would be useful for communications, navigation, and sonar imaging. Recent experiments demonstrated control of the shape of the LIB plasma volume, and thereby control

T. G. Jones; M. Hornstein; A. Ting; M. Nicholas

2009-01-01

311

May 31, 2005 Reflection Of Microwave Pulses From Acoustic Waves  

E-print Network

.g., see [2, 7, 11, 14]) that acoustic pressure waves will interact with electromagnetic signals in ways that often mimic interfacial partial reflection/partial transmission for the electromagnetic waves. Presently, ultrasonic acoustic waves are used in medical imaging of the heart, fetus, etc. Similarly, EM

312

46 | Acoustics Today | Summer 2014 Sonars and Strandings  

E-print Network

46 | Acoustics Today | Summer 2014 Sonars and Strandings: Are Beaked Whales the Aquatic Acoustic the question of the relationship between marine mammal strandings and intense sound sources (Frantzis, 1998, MS #50 Woods Hole, MA 02543 Centre for Marine Science and Technology Department of Imaging

313

Human cytochrome P450 4F11: Heterologous expression in bacteria, purification, and characterization of catalytic function  

PubMed Central

Human cytochrome P450 (P450) 4F11 is still considered an “orphan” because its function is not well characterized. A bacterial expression system was developed for human P450 4F11, producing ~230 nmol P450 from a 3-liter culture of Escherichia coli. P450 4F11 was purified and utilized for untargeted substrate searches in human liver extract using a liquid chromatography/mass spectrometry-based metabolomic and isotopic labeling approach (Z. Tang et al., Anal. Chem. 81, 3071–3078, 2009). Four fatty acids—palmitic, oleic, arachidonic, and docosahexaenoic—were identified in human liver and verified as substrates of P450 4F11. The products were characterized as ?-hydroxylated fatty acids by gas chromatography-mass spectrometry analysis of their trimethylsilyl derivatives. Kinetic analysis of the oxidation products confirmed that the fatty acids are substrates oxidized by P450 4F11. P450 4F11 also exhibited low activity for some drug N-demethylation reactions but none for activation of several procarcinogens. PMID:19932081

Tang, Zhongmei; Salamanca-Pinzón, Sandra Giovanna; Wu, Zhong-Liu; Xiao, Yi; Guengerich, F. Peter

2009-01-01

314

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

SciTech Connect

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}

Kim, H. [Department of Physics, Tohoku University, Sendai 980-77 (Japan)] [Department of Physics, Tohoku University, Sendai 980-77 (Japan); Tjernberg, O. [Material Physics, Royal Institute of Technology, S-10044, Stockholm (Sweden)] [Material Physics, Royal Institute of Technology, S-10044, Stockholm (Sweden); Chiaia, G. [INFM-Dip. Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, I-20133, Milano (Italy)] [INFM-Dip. Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, I-20133, Milano (Italy); Kumigashira, H.; Takahashi, T. [Department of Physics, Tohoku University, Sendai 980-77 (Japan)] [Department of Physics, Tohoku University, Sendai 980-77 (Japan); Duo, L. [INFM-Dip. Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, I-20133, Milano (Italy)] [INFM-Dip. Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, I-20133, Milano (Italy); Sakai, O.; Kasaya, M. [Department of Physics, Tohoku University, Sendai 980-77 (Japan)] [Department of Physics, Tohoku University, Sendai 980-77 (Japan); Lindau, I. [Department of Synchrotron Radiation Research, Institute of Physics, Lund University, Soelvegatan 14 S-223 62 Lund (Sweden)] [Department of Synchrotron Radiation Research, Institute of Physics, Lund University, Soelvegatan 14 S-223 62 Lund (Sweden)

1997-07-01

315

Visualization of acoustic fields in surface acoustic wave devices by means of X-ray topography  

Microsoft Academic Search

Reflection X-ray topographs from acousto-optic devices were measured under surface acoustic wave excitation. Enhanced sensitivity to small ultrasound amplitudes was achieved when the ultrasound wavelength was shorter than the X-ray extinction length. Under this condition an X-ray diffraction image of a high-frequency traveling surface acoustic wave was obtained despite the strains in the device caused by microelectronic processing.

E. Zolotoyabko; E. Jacobsohn; H. Bartunik; I. Polikarpov; I. Koelln; H. G. Krane

1995-01-01

316

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

Microsoft Academic Search

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

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

1999-01-01

317

Tissue elasticity using acoustic radiation force  

NASA Astrophysics Data System (ADS)

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.

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

2000-04-01

318

Characterizing Acoustic Attenuation of Homogeneous Media Using Focused Impulsive Acoustic Radiation Force  

PubMed Central

A new method to characterize a material’s attenuation using acoustic radiation force is proposed. Comparison of displacement magnitudes generated in a homogeneous material by acoustic radiation force excitations can be used to estimate the material’s attenuation when the excitations are applied over a range of focal depths while maintaining a constant lateral focal configuration. Acoustic attenuations are related to the inverse of the excitation focal depth that yields the greatest focal zone displacement for this protocol. Experimental studies in calibrated tissue-mimicking phantoms are presented to demonstrate the feasibility of this method. Attenuations ranging from 0.3 – 1.5 dB/cm/MHz were characterized over excitation focal depths ranging from 5 – 30 mm, with an accuracy of 0.1 ± 0.15 dB/cm/MHz. As currently implemented, this method is limited to characterizing materials that have homogeneous material properties and acoustic attenuations. This method for characterizing acoustic attenuation can be performed using conventional diagnostic scanners without any additional hardware and could also be performed concurrently with acoustic radiation force-based imaging modalities to generate images of mechanical properties and attenuation that are spatially co-registered with B-mode images. PMID:17094691

Palmeri, Mark L.; Frinkley, Kristin D.; Oldenburg, Katherine G.; Nightingale, Kathryn R.

2007-01-01

319

Acoustical standards news.  

PubMed

American National Standards (ANSI Standards) developed by Accredited Standards Committees S1, S2, S3, S3/SC 1, and S12 in the areas of acoustics, mechanical vibration and shock, bioacoustics, animal bioacoustics, and noise, respectively, are published by the Acoustical Society of America (ASA). In addition to these standards, ASA publishes catalogs of Acoustical Standards, both National and International. To receive copies of the latest Standards catalogs, please contact Susan B. Blaeser.Comments are welcomed on all material in Acoustical Standards News.This Acoustical Standards News section in JASA, as well as the National and International Catalogs of Acoustical Standards, and other information on the Standards Program of the Acoustical Society of America, are available via the ASA home page: http://acousticalsociety.org. PMID:25618085

Blaeser, Susan B; Schomer, Paul D

2015-01-01

320

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

SciTech Connect

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

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

2009-01-01

321

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

SciTech Connect

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

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

2011-01-01

322

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

PubMed Central

The apparently inimical relationship between magnetism and superconductivity has come under increasing scrutiny in a wide range of material classes, where the free energy landscape conspires to bring them in close proximity to each other. Particularly enigmatic is the case when these phases microscopically interpenetrate, though the manner in which this can be accomplished remains to be fully comprehended. Here, we present combined measurements of elastic neutron scattering, magnetotransport, and heat capacity on a prototypical heavy fermion system, in which antiferromagnetism and superconductivity are observed. Monitoring the response of these states to the presence of the other, as well as to external thermal and magnetic perturbations, points to the possibility that they emerge from different parts of the Fermi surface. Therefore, a single 4f state could be both localized and itinerant, thus accounting for the coexistence of magnetism and superconductivity. PMID:20457945

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

2010-01-01

323

A study of acoustic source generation mechanism of Magnetoacoustic Tomography.  

PubMed

Magnetoacoustic Tomography (MAT) is a non-invasive imaging modality for electrical conductivity with good contrast and high spatial resolution. We have analyzed the acoustic source generation mechanism of MAT and presented its physical model, including the simulations and experiments in this paper. In MAT, acoustic sources are generated in a conductive object placed in a static magnetic field. Pulsed current is injected into the object and produces a Lorentz force due to the static magnetic filed. Acoustic vibration was excited by the Lorentz force, and hence, ultrasound waves propagate in all directions and are collected with transducers placed around the object. The conductivity image can then be reconstructed with acoustic waves using some reconstruction algorithms. Because the acoustic source generation mechanism of MAT is the key problem of forward and inverse problems, we analyzed the physical process of acoustic source generation and presented the acoustic dipole source model according to the Lorentz force imposed on the object. In addition, computer simulations and experiments were also conducted. The results of simulations applying an acoustic dipole source model are consistent with experimental results. This study has cardinal significance for the accurate algorithm of MAT and provides a methodology and reference for acoustic source problems. PMID:24238804

Wang, Shigang; Zhang, Shunqi; Ma, Ren; Yin, Tao; Liu, Zhipeng

2014-01-01

324

Apolipoprotein A-I mimetic peptide 4F attenuates kidney injury, heart injury, and endothelial dysfunction in sepsis.  

PubMed

Kidney injury, heart injury, and cytokine-induced vascular hyperpermeability are associated with high rates of morbidity and mortality in sepsis. Although the mechanism remains unknown, apolipoprotein A-I (apoA-I) mimetic peptide 4F reduces inflammation and protects HDL levels, which are reduced in sepsis. We hypothesized that 4F also protects kidneys and hearts in a rat model of cecal ligation and puncture (CLP). We divided Wistar rats into groups: sham-operated (control), CLP, and CLP+4F (10 mg/kg body wt ip, 6 h after CLP). At 24 h post-CLP, we evaluated cardiac function, mean arterial pressure (MAP), heart rate (HR), baroreflex sensitivity, total cholesterol, LDL, HDL, serum cytokines, and inulin clearance. We performed immunoblotting for protein regulators of vascular permeability (Slit2 and Robo4) and endothelial nitric oxide synthase (eNOS) in kidney tissue. We evaluated heart mitochondria with electron microscopy. Although there was no difference in MAP, the HR was significantly higher in CLP rats than in control and CLP+4F rats. In CLP+4F rats, baroreflex sensitivity and cardiac function were completely protected from the effects of CLP, as was glomerular filtration; heart mitochondria morphology was improved; sepsis-induced changes in serum cholesterol, LDL, HDL, and apoA-I were less common; all cytokines were lower than in CLP rats; and expression of Slit2, Robo4, and eNOS was completely restored. Administration of 4F inhibits inflammatory responses and strengthens the vascular barrier, protecting kidneys and hearts in an HDL-dependent manner. To determine the extent of the protective effect of 4F, further studies are needed. PMID:24920733

Moreira, Roberto S; Irigoyen, Maria; Sanches, Talita R; Volpini, Rildo A; Camara, Niels O S; Malheiros, Denise M; Shimizu, Maria H M; Seguro, Antonio C; Andrade, Lucia

2014-09-01

325

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

PubMed Central

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

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

2014-01-01

326

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

SciTech Connect

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

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

2007-04-15

327

SAW-Modulated Image Device  

NASA Technical Reports Server (NTRS)

Imaging device uses surface-acoustic-wave (SAW) charge transfer for image readout. Spatial resolution of image changed electronically by changing frequency of applied signal. Surface acoustic waves create traveling longitudinal electric fields. These fields create potential wells that carry along stored charges. Charges injected into wells by photoelectric conversion when light strikes device.

Benz, H. F.

1985-01-01

328

Acoustics 08 Paris Finite element modeling of thermoviscous acoustics in  

E-print Network

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

Boyer, Edmond

329

Acoustic inverse scattering via Helmholtz operator factorization and optimization q  

E-print Network

Acoustic inverse scattering via Helmholtz operator factorization and optimization q Shen Wang 2010 Keywords: Imaging Inverse scattering Wave-equation tomography Optimization Helmholtz solver, in terms of inhomogeneous Helmholtz equations. We use a higher order finite difference scheme

Xia, Jianlin

330

A new photocatalyst: Bi2TiO4F2 nanoflakes synthesized by a hydrothermal method.  

PubMed

A pure phase of Bi(2)TiO(4)F(2) nanoflakes with layered Aurivillius structure are synthesized by a simple hydrothermal method. The as-prepared sample is characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and UV-vis diffuse reflectance spectroscopy. The OH radicals produced during the photocatalytic reaction is detected by a photoluminescence (PL) technique. The electronic structure is investigated by DFT calculations. The photocatalytic properties of Bi(2)TiO(4)F(2) are explored by degradation of Rhodamine B (RhB) and phenol. The results show that Bi(2)TiO(4)F(2) exhibits much higher photocatalytic performances than Bi(4)Ti(3)O(12) due to the unique layered structure and the existence of F. F acts as an electron trapper, which enhances the separation of photogenerated electron-hole pairs, and lead to higher photocatalytic activity. Reaction with terephthalic acid demonstrates that OH radicals are formed as a result of UV irradiation of Bi(4)TiO(4)F(2) in solution, in agreement with the proposed mechanism. Thus, Bi(2)TiO(4)F(2) can be used as a new efficient photocatalyst. PMID:21814697

Wang, Shaoying; Huang, Baibiao; Wang, Zeyan; Liu, Yuanyuan; Wei, Wei; Qin, Xiaoyan; Zhang, Xiaoyang; Dai, Ying

2011-12-21

331

Acoustic rainbow trapping  

PubMed Central

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

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

2013-01-01

332

Acoustic to articulatory inversion  

E-print Network

The context of this work is speech analysis. The subject deals with acoustic-to-articulatory inversion, i.e. the recovery of the temporal evolution of the vocal tract shape from the signal. This topic is important because it is likely to give rise to applications in the domains of speech coding as well as second language learning. Acoustic-to-articulatory inversion relies on an analysis by synthesis approach. The synthesis is the articulatory synthesis, which, from the vocal tract shape given by an articulatory model specifying the position and shape of the tongue, lowers jaw, lips and larynx produces the acoustical signal by means of an acoustical simulation. This synthesis system is used to build a table consisting of pairs of articulatory and acoustical vectors[1]. During inversion, all the articulatory shapes whose acoustic parameters are close to those observed in the original speech signal. 2

unknown authors

333

Surface acoustic wave devices  

Microsoft Academic Search

Starting with an introduction to surface acoustic waves, their generation and detection using interdigital transducers (IDTs) on piezoelectric materials (e.g. LiNbO3 and ZnO) will be reviewed. Then the application of surface acoustic waves in electronic devices will be presented. Moreover, recent studies, using the technique of attaching the material of investigation onto the sound path of the acoustic delay line

C. Müller; A. Nateprov; G. Obermeier; M. Klemm; V. Tsurkan; A. Wixforth; R. Tidecks; S. Horn

2007-01-01

334

Underwater acoustic networks  

Microsoft Academic Search

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

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

2000-01-01

335

Natural History of Acoustic Neuromas  

PubMed Central

The growth rate of acoustic neuromas was studied in a series of 50 patients who underwent follow-up imaging studies, since surgery was not performed after the initial diagnostic study or only performed after the follow-up studies. In 50% of the cases the tumor did not grow during the length of the follow-up. In the other patients the growth was less than 50% of the original tumor size in all but four. No correlation was observed between tumor growth, length of the follow-up, and age of the patient. Our results suggest a change in the management of this benign tumor. PMID:17170806

Valvassori, Galdino E.; Shannon, Michael

1991-01-01

336

STOVL acoustic fatigue technologies  

NASA Technical Reports Server (NTRS)

This paper assesses the state of the art in acoustic fatigue technologies as applied to an advanced supersonic short takeoff and vertical landing (STOVL) aircraft. The topics covered include advanced materials, fatigue, acoustic loads prediction, and stress response prediction. Advanced materials are compared from the standpoints of fatigue resistance and fatigue data availability. State of the art acoustic load prediction techniques are evaluated. Subsonic and supersonic jet noise generation mechanisms, axisymmetric and two-dimensional nozzles, and noise suppression methods are covered. Stress response prediction methods for acoustic, thermal, and maneuvering loads are addressed and the necessity of structural analysis with all three loading types applied simultaneously is assessed.

Groen, David S.

1988-01-01

337

Acoustic Doppler Current Profilers  

USGS Multimedia Gallery

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

2009-08-04

338

Low frequency acoustic microscope  

DOEpatents

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

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

1986-11-04

339

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

SciTech Connect

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.

Xia Shangda [Institute of Modern Physics, Chongqing University of Post and Telecommunications, Chongqing 400065 (China); Department of Physics, University of Science and Technology of China, Hefei 230036 (China); Duan Changkui [Institute of Modern Physics, Chongqing University of Post and Telecommunications, Chongqing 400065 (China)]. E-mail: duanck@cqupt.edu.cn; Deng Quan [Institute of Modern Physics, Chongqing University of Post and Telecommunications, Chongqing 400065 (China); Ruan Gang [Institute of Modern Physics, Chongqing University of Post and Telecommunications, Chongqing 400065 (China)

2005-09-15

340

Acoustic superfocusing by solid phononic crystals  

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

341

MicroRNAs block assembly of eIF4F translation initiation complex in Drosophila.  

PubMed

miRNAs silence their complementary target mRNAs by translational repression as well as by poly(A) shortening and mRNA decay. In Drosophila, miRNAs are typically incorporated into Argonaute1 (Ago1) to form the effector complex called RNA-induced silencing complex (RISC). Ago1-RISC associates with a scaffold protein GW182, which recruits additional silencing factors. We have previously shown that miRNAs repress translation initiation by blocking formation of the 48S and 80S ribosomal complexes. However, it remains unclear how ribosome recruitment is impeded. Here, we examined the assembly of translation initiation factors on the target mRNA under repression. We show that Ago1-RISC induces dissociation of eIF4A, a DEAD-box RNA helicase, from the target mRNA without affecting 5' cap recognition by eIF4E in a manner independent of GW182. In contrast, direct tethering of GW182 promotes dissociation of both eIF4E and eIF4A. We propose that miRNAs act to block the assembly of the eIF4F complex during translation initiation. PMID:25280104

Fukaya, Takashi; Iwakawa, Hiro-Oki; Tomari, Yukihide

2014-10-01

342

Anomalous Eu valence state and superconductivity in undoped Eu3Bi2S4F4.  

PubMed

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

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

2014-10-29

343

The Ba 4d-4f giant dipole resonance in complex Ba/Si compounds  

NASA Astrophysics Data System (ADS)

The shape of the Ba 4d-4f giant dipole resonance is studied for Ba atoms embedded inside complex Si networks covering structures consisting of Si nanocages and nanotubes, i.e. the clathrate Ba8Si46, the complex compound BaSi6, and the semiconducting BaSi2. Here, non-resonant x-ray Raman scattering is used to investigate confinement effects on the shape of the giant resonance in the vicinity of the Ba NIV, V-edge. The distinct momentum transfer dependence of the spectra is analyzed and discussed. The measurements are compared to calculations of the giant resonance within time-dependent local density approximation in the dipole limit. No modulation of the giant resonance’s shape for Ba atoms confined in different local environments was observed, in contrast to the calculations. The absence of such shape modulation for complex Ba/Si compounds is discussed providing important implications for further studies of giant resonance phenomena utilizing both theory and experiment.

Sahle, Ch J.; Sternemann, C.; Sternemann, H.; Tse, J. S.; Gordon, R. A.; Desgreniers, S.; Maekawa, S.; Yamanaka, S.; Lehmkühler, F.; Wieland, D. C. F.; Mende, K.; Huotari, S.; Tolan, M.

2014-02-01

344

The extreme ultraviolet emissions of W23+(4f5)  

NASA Astrophysics Data System (ADS)

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

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

2013-07-01

345

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

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

346

Pressure-enhanced superconductivity in Eu3Bi2S4F4  

NASA Astrophysics Data System (ADS)

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 0.68 GPa?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 the two superconducting phases. 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.

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

2014-12-01

347

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

SciTech Connect

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

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

2013-08-15

348

Acoustic visualization of cold flakes and crack propagation in aluminum alloy die-cast plate  

Microsoft Academic Search

Acoustic images received at different depths of aluminum alloy (ADC12) die-cast plates containing coarse cold flakes were compared with microstructures at the same depth. The bright and dark regions in the acoustic images coincided with the oxide layer on the initially solidified surface of the cold flake and the body of the cold flake, respectively. These results show the ability

A. K. M. Aziz Ahamed; Hiroshi Kato; Kensuke Kageyama; Toru Komazaki

2006-01-01

349

Surface acoustic wave devices  

Microsoft Academic Search

The paper outlines the design features, principles of operation, fabrication, and electronic applications of surface acoustic wave (SAW) devices. Surface acoustic waves can exist in any elastic medium at its surface, and devices using these waves are made on piezoelectric media having a preferred direction of propagation. A SAW device usually consists of the SAW element on its substrate plus

R. D. Kennedy

1977-01-01

350

Acoustics Critical Readiness Review  

NASA Technical Reports Server (NTRS)

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

Ballard, Kenny

2010-01-01

351

Marine environmental acoustics  

Microsoft Academic Search

The Marine Environmental Acoustics Program of the Marine Physical Laboratory can be best typified as one with an experimental emphasis, addressing the acoustic, hydrodynamic, magnetic environments of the ocean. In particular we are concerned with understanding the interaction of the environment with the Navy's needs in undersea detection, localization and communication.

K. M. Watson; V. C. Anderson

1983-01-01

352

Introduction to acoustic emission  

NASA Technical Reports Server (NTRS)

Typical acoustic emission signal characteristics are described and techniques which localize the signal source by processing the acoustic delay data from multiple sensors are discussed. The instrumentation, which includes sensors, amplifiers, pulse counters, a minicomputer and output devices is examined. Applications are reviewed.

Possa, G.

1983-01-01

353

Acoustic ground impedance meter  

NASA Technical Reports Server (NTRS)

A method and apparatus are presented for measuring the acoustic impedance of a surface in which the surface is used to enclose one end of the chamber of a Helmholz resonator. Acoustic waves are generated in the neck of the resonator by a piston driven by a variable speed motor through a cam assembly. The acoustic waves are measured in the chamber and the frequency of the generated acoustic waves is measured by an optical device. These measurements are used to compute the compliance and conductance of the chamber and surface combined. The same procedure is followed with a calibration plate having infinite acoustic impedance enclosing the chamber of the resonator to compute the compliance and conductance of the chamber alone. Then by subtracting, the compliance and conductance for the surface is obtained.

Zuckerwar, A. J. (inventor)

1984-01-01

354

Acoustic particle velocity horns.  

PubMed

The paper considers receiving acoustic horns designed for particle velocity amplification and suitable for use in vector sensing applications. Unlike conventional horns, designed for acoustic pressure amplification, acoustic velocity horns (AVHs) deliver significant velocity amplification even when the overall size of the horn is much less than an acoustic wavelength. An AVH requires an open-ended configuration, as compared to pressure horns which are terminated at the throat. The appropriate formulation, based on Webster's one-dimensional horn equation, is derived and analyzed for single conical and exponential horns as well as for double-horn configurations. Predicted horn amplification factors (ratio of mouth-to-throat radii) were verified using numerical modeling. It is shown that three independent geometrical parameters principally control a horn's performance: length l, throat radius R(1), and flare rate. Below a predicted resonance region, velocity amplification is practically independent of frequency. Acoustic velocity horns are naturally directional, providing maximum velocity amplification along the boresight. PMID:22559364

Donskoy, Dimitri M; Cray, Benjamin A

2012-05-01

355

Brn-3c (POU4F3) regulates BDNF and NT-3 promoter activity R. Lee Clougha  

E-print Network

Brn-3c (POU4F3) regulates BDNF and NT-3 promoter activity R. Lee Clougha , Richa Suda , Noa Davis of hair cell loss potentially through lower BDNF and NT-3 expression. Using transient transfection assays we show that Brn-3c is capable of activating both BDNF and NT-3 promoters in inner ear sensory

Avraham, Karen

356

Acoustic Fresnel lenses with extraordinary transmission  

NASA Astrophysics Data System (ADS)

We investigate numerically and experimentally highly efficient acoustic lenses based on the principle of extraordinary acoustic transmission. We study circular, flat lenses composed of perforated air channels. The geometry is similar to binary Fresnel lenses, and the lenses exploit several resonance mechanisms to enhance the transmission, such as Fabry-Perot resonances in the channels and cavity resonances on the lens surface. The proposed lenses are able to transmit up to 83% of the incident energy and generate sharp focusing with very high amplification (up to 16 dB experimentally). Furthermore, the resulting lenses are thinner than other designs providing similar performance, making them ideal candidates for application in acoustic imaging and medical diagnostics.

Molerón, Miguel; Serra-Garcia, Marc; Daraio, Chiara

2014-09-01

357

Cyclo-octafluorobutane (PFC-318, c-C4F8) in the global atmosphere  

NASA Astrophysics Data System (ADS)

The perfluorocarbon (PFC) cyclo-octafluorobutane (PFC-318, c-C4F8) is a very long-lived (up to 3,200 years) and potent greenhouse gas (100-year global warming potential up to 10,300) with a wide range of industrial uses. We present an update of our PFC-318 archived air and in situ measurements from remote and urban AGAGE (Advanced Global Atmospheric Gases Experiment) sites and affiliated stations in both hemispheres. Most importantly, we have significantly improved our Southern Hemisphere (SH) data density by measuring the Cape Grim Air Archive (1970s-2010). Combined with our previously presented measurements of archived Northern Hemisphere (NH) flasks (1973-2009), we provide thirty year spanning records for both hemispheres. We have also further extended our in situ records by continuing our measurements at all remote stations, with the longest hemispheric records starting in November 2007 at Jungfraujoch (NH) and in June 2010 at Cape Grim (SH). We compare our data with those of Oram (1999) and Oram et al. (2011), who focus on SH data alone, and with other previous data sets. From our measurements, we derive emission estimates using a chemical transport model and inverse method, and compare our results to previous measurement based emission estimates (top-down) and to the EDGAR emission database (bottom-up). As stated previously (Mühle et al., 2010), we find emissions of ~1 Gg/yr in recent years while EDGAR estimates only 0.02 Gg/yr for 2005, similar to what Oram et al. (2011) find. We conclude that PFC-318 is the third most important PFC in terms of abundance and CO2-equivalent emissions. We continue to observe mostly baseline concentrations at remote AGAGE stations and urban sites in the USA, Europe, and Australia, in contrast to frequent pollution episodes measured at sites in East Asia, indicating significant regional emissions in East Asia, as found by Saito et al. (2010). EDGAR, Emission Database for Global Atmospheric Research, release version 4.1. http://edgar.jrc.ec.europa.eu, last accessed 2011. Mühle et al., Cyclo-octafluorobutane (PFC-318) in the global atmosphere, Abstract A51D-0143, AGU Fall Meeting, San Francisco, CA, 13-17 Dec., 2010. Oram, Trends of long-lived anthropogenic halocarbons in the Southern Hemisphere and model calculation of global emissions, Ph.D. thesis, University of East Anglia, Norwich, U.K., 1999. Oram et al., Long-term tropospheric trend of octafluorocyclobutane (c-C4F8 or PFC-318), Atmos. Chem. Phys. Discuss., 11, 7, 19089-19111, 10.5194/acpd-11-19089-2011, 2011. Saito et al., Large Emissions of Perfluorocarbons in East Asia Deduced from Continuous Atmospheric Measurements, Environ. Sci. Technol., 44(11), 4089-4095, doi:10.1021/es1001488, 2010.

Muhle, J.; Vollmer, M. K.; Ivy, D. J.; Fraser, P.; Arnold, T.; Harth, C. M.; Salameh, P.; O'Doherty, S.; Young, D.; Steele, P.; Krummel, P. B.; Leist, M.; Rhee, T. S.; Schmidbauer, N.; Lunder, C.; Kim, J.; Kim, K.; Reimann, S.; Simmonds, P.; Prinn, R. G.; Weiss, R. F.

2011-12-01

358

Scanning probe acoustic microscopy of extruded starch materials: direct visual evidence of starch crystal.  

PubMed

Scanning probe acoustic microscopy (SPAM) has been successfully used to study inorganic and keratin biomaterials. However, few studies have attempted to apply SPAM to structural study of non-keratin organic materials such as starch based materials. This study investigated hardness and surface finish to establish sample preparation method suitable for SPAM imaging and acquired clear acoustic images of extruded starch materials. Acquired acoustic images directly exhibited certain structure of starch materials and provided visual evidence of starch material components and aggregates. In addition, through correlating acoustic images with X-ray diffraction data, crystal-structural information in nano-scale was obtained and acoustic image contrast showed a linear relationship with starch amylose content in extruded starch materials. PMID:23987357

Liu, Zhongdong; Liu, Boxiang; Li, Mengxing; Wei, Min; Li, Hua; Liu, Peng; Wan, Tuo

2013-10-15

359

RNA editing and regulation of Drosophila 4f-rnp expression by sas-10 antisense readthrough mRNA transcripts  

PubMed Central

We have previously described an example of extensively A-to-G edited cDNA derived from adult heads of the fruitfly Drosophila melanogaster. In that study, the source of the predicted antisense RNA pairing strand for template recognition by dADAR editase was not identified, and the biological significance of the observed hyperediting was not known. Here, we address each of these questions. 4f-rnp and sas-10 are closely adjacent X-linked genes located on opposite DNA strands that produce convergent transcripts. We show that developmentally regulated antisense sas-10 readthrough mRNA arises by activation of an upstream promoter P2 during the late embryo stage of fly development. The sas-10 readthrough transcripts pair with 4f-rnp mRNA to form double-stranded molecules, as indicated by A-to-G editing observed in both RNA strands. It would be predicted that perfect RNA duplexes would be targeted for modification/degradation by enzyme pathways that recognize double-stranded RNAs, leading to decline in 4f-rnp mRNA levels, and this is what we observe. The observation using quantitative RT-PCR that sas-10 readthrough and 4f-rnp transcript levels are inversely related suggests a role for the antisense RNA in posttranscriptional regulation of 4f-rnp gene expression during development. Potential molecular mechanisms that could lead to this result are discussed, one of which is targeted transcript degradation via the RNAi pathway. Insofar as the dADAR editase and RNAi pathways are known to be constitutive in this system, it is likely that control of antisense RNA transcription is the rate-limiting factor. The results provide insight into roles of naturally occurring antisense RNAs in regulation of eukaryotic gene expression. PMID:12756328

PETERS, NICK T.; ROHRBACH, JUSTIN A.; ZALEWSKI, BRIAN A.; BYRKETT, COLLEEN M.; VAUGHN, JACK C.

2003-01-01

360

Preparation of Amorphous Fluorinated Carbon Film Using Low Global-Warming Potential Gas, C4F6, by Plasma Enhanced Chemical Vapor Deposition  

Microsoft Academic Search

Low-dielectric constant amorphous fluorinated carbon (a-C:F) films were prepared using plasma enhanced chemical vapor deposition (PECVD) from C4F6 gas, which is expected to be a substitutional gas due to its low global-warming potential (GWP). Kinetic analysis revealed that C4F6 (hexafluoro-1,3-butadiene) or related molecules were a main deposition precursor and that C4F6 concentration in the plasma affected the C-CF bond ratio

Hiroki Watanabe; Takumi Tokimitsu; Jyunko Shiga; Nobuo Haneji; Yukihiro Shimogaki

2006-01-01

361

Preparation and Characterization of Amorphous Fluorinated Carbon Film Using Low-Global-Warming-Potential Gas, C4F6, by Plasma-Enhanced Chemical Vapor Deposition  

Microsoft Academic Search

Low-dielectric-constant amorphous fluorinated carbon (a-C:F) films were prepared using plasma-enhanced chemical vapor deposition (PECVD) from C4F6 (hexafluoro-1,3-butadiene) gas, which is expected to be a substitutional gas owing to its low global warming potential (GWP). Kinetic analysis revealed that the density of C4F6 in plasma has a proportional relation to film growth rate, which suggests that C4F6 is a main deposition

Hiroki Watanabe; Yukihiro Shimogaki

2006-01-01

362

Generation of Sound Bullets with a Nonlinear Acoustic Lens  

E-print Network

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.

Alessandro Spadoni; Chiara Daraio

2009-08-31

363

Intrinsically irreversible acoustic heat engines  

SciTech Connect

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.

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

1985-01-01

364

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

Microsoft Academic Search

Autonomous underwater vehicles (AUVs) present the important advantage of being able to approach the seafloor more closely than surface vessel surveys can. To collect bathymetric data, bottom material information, and sub-surface images, multibeam echosounder, sidescan sonar (SSS) and subbottom profiler (SBP) equipment mounted on an AUV are powerful tools. The 3000m class AUV URASHIMA was developed by the Japan Agency

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

2011-01-01

365

Acoustic cooling engine  

DOEpatents

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.

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

366

Comparison of Diagnostic Efficacy of Contrast-Enhanced Ultrasound, Acoustic Radiation Force Impulse Imaging, and Their Combined Use in Differentiating Focal Solid Thyroid Nodules  

PubMed Central

Background A key limitation of conventional ultrasound (US) includes poor differentiation of benign from malignant thyroid nodules. Contrast-enhanced US (CEUS) and acoustic radiation force impulse (ARFI) could provide better characterization of focal thyroid nodules; however, no studies have compared their efficacies. Objective To evaluate the diagnostic efficacy of conventional US,CEUS, ARFI, and their combined use in differentiating focal solid thyroid nodules. Methods One-hundred-forty-six Chinese patients with 175 thyroid nodules (119 benign and 56 malignant) were prospectively enrolled. Each patients underwent conventional US, CEUS and ARFI, respectively. The diagnostic performance of the conventional US, CEUS, ARFI, combined use of either CEUS or ARFI and combined use of the three modalities were assessed and compared using Pathological diagnosis (histological/cytological) as the reference method. Results There were no significant differences between individual groups (CEUS vs US, P?=?0.279, ARFI vs US, P?=?0.372, CEUS vs ARFI, P?=?0.849), combined use of US and CEUS or combined use of US and ARFI yielded significant difference compared to US. (combination of US & CEUS vs US, P?=?0.021; combination of US & ARFI vs US, P?=?0.036). The combination of three modalities significantly improved the diagnostic accuracy compared with either combination of conventional US and CEUS or combination of conventional US and ARFI (P?=?0.045 and P ?=?0.027, respectively). Conclusions CEUS and ARFI can be used as an additional tool in the diagnostic work up of thyroid nodules. The combination of CEUS with ARFI can significantly improve the diagnostic accuracy. PMID:24594879

Deng, Jin; Zhou, Ping; Tian, Shuang-ming; Zhang, Lu; Li, Jia-le; Qian, Ying

2014-01-01

367

PRSEUS Acoustic Panel Fabrication  

NASA Technical Reports Server (NTRS)

This report describes the development of a novel structural concept, Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS), that addresses the demanding fuselage loading requirements for the Hybrid Wing or Blended Wing Body (BWB) airplane configuration with regards to acoustic response. A PRSEUS panel was designed and fabricated and provided to NASA-LaRC for acoustic response testing in the Structural Acoustics Loads and Transmission (SALT) facility). Preliminary assessments of the sound transmission characteristics of a PRSEUS panel subjected to a representative Hybrid Wing Body (HWB) operating environment were completed for the NASA Environmentally Responsible Aviation (ERA) Program.

Nicolette, Velicki; Yovanof, Nicolette P.; Baraja, Jaime; Mathur, Gopal; Thrash, Patrick; Pickell, Robert

2011-01-01

368

Acoustical heat pumping engine  

DOEpatents

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.

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

1983-08-16

369

Acoustic well cleaner  

DOEpatents

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

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

1997-01-21

370

Quantitative flaw characterization with scanning laser acoustic microscopy  

NASA Technical Reports Server (NTRS)

Surface roughness and diffraction are two factors that have been observed to affect the accuracy of flaw characterization with scanning laser acoustic microscopy. Inaccuracies can arise when the surface of the test sample is acoustically rough. It is shown that, in this case, Snell's law is no longer valid for determining the direction of sound propagation within the sample. The relationship between the direction of sound propagation within the sample, the apparent flaw depth, and the sample's surface roughness is investigated. Diffraction effects can mask the acoustic images of minute flaws and make it difficult to establish their size, depth, and other characteristics. It is shown that for Fraunhofer diffraction conditions the acoustic image of a subsurface defect corresponds to a two-dimensional Fourier transform. Transforms based on simulated flaws are used to infer the size and shape of the actual flaw.

Generazio, E. R.; Roth, D. J.

1986-01-01

371

The crystal structure of bøgvadite (Na2SrBa2Al4F20)  

NASA Astrophysics Data System (ADS)

The crystal structure of bøgvadite, Na2SrBa2Al4F20, has been solved and refined to a R1 factor of 4.4 % from single-crystal data (Mo K? X-ray diffraction, CCD area detector) on a sample from the cryolite deposit at Ivittuut, SW Greenland. Bøgvadite is monoclinic, P21/ n space group, with unit cell parameters a = 7.134(1), b = 19.996(3) and c = 5.3440(8) Å, ? = 90.02(1)o. A close proximity of the crystal structure to an orthorhombic symmetry and the presence of the two twin components in a nearly 1:1 ratio suggest that the investigated bøgvadite crystal has originally formed as a high-temperature orthorhombic polymorph which on cooling transformed to the stable low temperature monoclinic structure. The bøgvadite crystal structure has groupings of cation-fluoride coordination polyhedra similar to those found in the crystal structures of the genetically closely associated minerals jarlite and jørgensenite. However, its structure type is different from the latter two. The fluoridoaluminate framework of bøgvadite consists of infinite zig-zag chains of cis-connected AlF6 coordination octahedra. The 1 ?[AlF5] chains are interconnected by infinite chains of Na-F coordination polyhedra which extend in the same direction. Na is coordinated by nine F atoms if its full surrounding is taken in consideration, but makes significant chemical bonds only to closest five. The chains of AlF6 and NaF9 coordination polyhedra form double layers. In the centre of layers, relatively large voids in the form of pentagonal antiprisms are occupied by Sr atoms which make chemical bonds with the closest six F atoms. Between the SrF10 coordinations in the centre of layers run empty channels. The double layers are interconnected by Ba atoms which are coordinated by eight F atoms and fill the spaces between the layers. Bøgvadite belongs to the group of fluoridoaluminates with infinite chains of cis-connected AlF6 coordination octahedra, alike those found in the crystal structures of Ba-fluoridoaluminates.

Bali?-Žuni?, Ton?i

2014-08-01

372

Improving limited-view photoacoustic tomography with an acoustic reflector  

PubMed Central

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.

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

2013-01-01

373

Examination of silicon solar cells by means of the Scanning Laser Acoustic Microscope (SLAM)  

NASA Technical Reports Server (NTRS)

The Scanning Laser Acoustic Microscope produces images of internal structure in materials. The acoustic microscope is an imaging system based upon acoustic rather than electromagnetic waves. Variations in the elastic propertis are primarily responsible for structure visualized in acoustic micrographs. The instrument used in these investigations is the SONOMICROSCOPE 100 which can be operated at ultrasonic frequencies of from 30 MHz to 500 MHz. The examination of the silicon solar cells was made at 100 MHz. Data are presented in the form of photomicrographs.

Vorres, C.; Yuhas, D. E.

1981-01-01

374

Properties of cC4F8 inductively coupled plasmas. II. Plasma chemistry and reaction mechanism for modeling of Ar\\/cC4F8\\/O2 discharges  

Microsoft Academic Search

Gas mixtures containing Ar, c-C4F8, O2, and CO are often used for the plasma etching of silicon dioxide. Gas phase reaction mechanisms are required for first principles modeling of these systems to both provide insights to the plasma chemistry and to help optimize the process. In this article, results from computational and experimental investigations of the plasma chemistry of inductively

Alex V. Vasenkov; Xi Li; Gottlieb S. Oehrlein; Mark J. Kushner

2004-01-01

375

Initial nucleation site formation due to acoustic droplet vaporization  

PubMed Central

Acoustic droplet vaporization (ADV) is the selective vaporization of liquid microdroplets using ultrasound, resulting in gas bubbles. The ADV process has been proposed as a tool in biomedical applications such as gas embolotherapy, drug delivery, and phase-change contrast agents. Using a 7.5?MHz focused transducer, the initial gas nucleus formed in perfluorocarbon microdroplets was directly visualized using ultra-high speed imaging. The experimental results of initial nucleation site location were compared to a 2D axisymmetric linear acoustic model investigating the focal spot of the acoustic wave within the microdroplets. Results suggest a wavelength to droplet diameter dependence on nucleation site formation. PMID:24711671

Li, David S.; Kripfgans, Oliver D.; Fabiilli, Mario L.; Brian Fowlkes, J.; Bull, Joseph L.

2014-01-01

376

Formation of toroidal bubbles from acoustic droplet vaporization  

PubMed Central

Acoustic droplet vaporization (ADV) is the selective vaporization of liquid microdroplets using ultrasound to produce stable gas bubbles. ADV is the primary mechanism in an ultrasound based cancer therapy, called gas embolotherapy, where the resulting bubbles are used to create localized occlusions leading to tumor necrosis. In this investigation, early time scale events including phase change are directly visualized using ultra-high speed imaging. Modulating elevated acoustic pressure or pulse length resulted in toroidal bubbles. For sufficiently short pulses (4 cycles at 7.5?MHz), toroidal bubble formation could be avoided, regardless of acoustic pressures tested. PMID:24711672

Li, David S.; Kripfgans, Oliver D.; Fabiilli, Mario L.; Brian Fowlkes, J.; Bull, Joseph L.

2014-01-01

377

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

PubMed

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

Anita, K; Rajmuhon Singh, N

2011-10-15

378

High resolution photoacoustic microscopy on a surface acoustic wave device  

Microsoft Academic Search

Photoacoustic imaging of microscopic metal film test structures on a surface acoustic wave device at 76-MHz light modulation frequency is reported. The samples are evaporated on a YZ LiNbO3 crystal surface and are scanned through the focus spot of a mode-locked dye laser beam. The optically generated surface acoustic waves are detected by means of a resonant interdigital transducer. Synchronization

G. Veith

1982-01-01

379

Space, time and acoustics  

E-print Network

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

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

1988-01-01

380

Compact acoustic refrigerator  

SciTech Connect

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.

Bennett, G.A.

1991-12-31

381

Identifying the Acoustic Neuroma  

MedlinePLUS

... only a few millimeters in diameter. An auditory brainstem response test (a.k.a. ABR, BAER, or ... the circuit from the inner ear to the brainstem pathways. An acoustic neuroma can interfere with the ...

382

Compact acoustic refrigerator  

DOEpatents

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

Bennett, G.A.

1992-11-24

383

Numerical Techniques in Acoustics  

NASA Technical Reports Server (NTRS)

This is the compilation of abstracts of the Numerical Techniques in Acoustics Forum held at the ASME's Winter Annual Meeting. This forum was for informal presentation and information exchange of ongoing acoustic work in finite elements, finite difference, boundary elements and other numerical approaches. As part of this forum, it was intended to allow the participants time to raise questions on unresolved problems and to generate discussions on possible approaches and methods of solution.

Baumeister, K. J. (compiler)

1985-01-01

384

Precategorical acoustic storage (PAS)  

Microsoft Academic Search

A system for precategorical storage of acoustic information is described. Material in this store is subject to overwriting\\u000a and to decay with time. Precategorical Acoustic Storage (PAS) receives information only from the ears; it is not affected\\u000a by silent rehearsal or by visual stimulation, and is explicitly distinguished from storage in terms of articulation. Two experiments\\u000a are reported in which

Robert G. Crowder; John Morton

1969-01-01

385

Synthesis and photoluminescence properties of novel red emitting phosphor Sr2LiSiO4F:Eu3+  

NASA Astrophysics Data System (ADS)

Novel red phosphors Sr2LiSiO4F:xEu3+ (0.01 ? x ? 0.15) were synthesized using high temperature solid-state reaction. The phosphors were characterized by X-ray diffraction (XRD) and photoluminescence (PL) as well as lifetimes. The influence of the doping concentration of Eu3+ on its relative emission intensity and decay behavior was discussed. The PL spectra show that the phosphors Sr2LiSiO4F:Eu3+ can be effectively excited by near ultraviolet (n-UV) light, and exhibit red emission with a dominant 5D0 ? 7F2 transition at 617 nm. The decay time gradually decreases with increasing of the Eu3+ concentrations in the order of millisecond. The results indicate this phosphor could be a potential candidate as red emitting phosphor for n-UV InGaN-based w-LEDs.

Xie, Mubiao; Zeng, Lihua; Zhou, Xiaoping; Xie, Feifei

2015-01-01

386

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

PubMed Central

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

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

2012-01-01

387

Preliminary characterization of a one-axis acoustic system. [acoustic levitation for space processing  

NASA Technical Reports Server (NTRS)

The acoustic fields and levitation forces produced along the axis of a single-axis resonance system were measured. The system consisted of a St. Clair generator and a planar reflector. The levitation force was measured for bodies of various sizes and geometries (i.e., spheres, cylinders, and discs). The force was found to be roughly proportional to the volume of the body until the characteristic body radius reaches approximately 2/k (k = wave number). The acoustic pressures along the axis were modeled using Huygens principle and a method of imaging to approximate multiple reflections. The modeled pressures were found to be in reasonable agreement with those measured with a calibrated microphone.

Oran, W. A.; Reiss, D. A.; Berge, L. H.; Parker, H. W.

1979-01-01

388

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

NASA Technical Reports Server (NTRS)

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

Tsang, T.; Ghose, S.

1972-01-01

389

Arginine transport in human erythroid cells: discrimination of CAT1 and 4F2hc/y+LAT2 roles.  

PubMed

Since arginine metabolites, such as nitric oxide and polyamines, influence the expression of genes involved in erythroid differentiation, the transport of the cationic amino acid may play an important role in erythroid cells. However, available data only concern the presence in these cells of CAT1 transporter (system y(+)), while no information exists on the role of the heterodimeric transporters of system y(+)L (4F2hc/y(+)LAT1 and 4F2hc/y(+)LAT2) which operates transmembrane arginine fluxes cis-inhibited by neutral amino acids in the presence of sodium. Using erythroleukemia K562 cells and normal erythroid precursors, we demonstrate here that arginine transport in human erythroid cells is due to the additive contributions of a leucine-sensitive and leucine-insensitive component. In both cell types, leucine inhibition of arginine influx is much less evident in the absence of sodium, a hallmark of system y(+)L. In K562 cells, N-ethylmaleimide, a known inhibitor of CAT transporters (system y(+)), suppresses only a fraction of arginine influx corresponding to leucine-insensitive uptake. Moreover, in Xenopus oocytes coexpressing 4F2hc and y(+)LAT2, leucine exerts a marked inhibition of arginine transport, partially dependent on sodium, while no inhibition is seen in oocytes expressing CAT1. Lastly, silencing of SLC7A6, the gene for y(+)LAT2, lowers arginine transport and doubles the intracellular content of the cationic amino acid in K562 cells. We conclude that arginine transport in human erythroid cells is due to both system y(+) (CAT1 transporter) and system y(+)L (4F2hc/y(+)LAT2 isoform), which mainly contribute, respectively, to the influx and to the efflux of the cationic amino acid. PMID:19562367

Rotoli, Bianca Maria; Closs, Ellen I; Barilli, Amelia; Visigalli, Rossana; Simon, Alexandra; Habermeier, Alice; Bianchi, Nicoletta; Gambari, Roberto; Gazzola, Gian C; Bussolati, Ovidio; Dall'Asta, Valeria

2009-10-01

390

Flow–flame interactions causing acoustically coupled heat release fluctuations in a thermo-acoustically unstable gas turbine model combustor  

Microsoft Academic Search

A detailed analysis of the flow–flame interactions associated with acoustically coupled heat-release rate fluctuations was performed for a 10kW, CH4\\/air, swirl stabilized flame in a gas turbine model combustor exhibiting self-excited thermo-acoustic oscillations at 308Hz. High-speed stereoscopic particle image velocimetry, OH planar laser induced fluorescence, and OH? chemiluminescence measurements were performed at a sustained repetition rate of 5kHz, which was

A. M. Steinberg; I. Boxx; M. Stöhr; C. D. Carter; W. Meier

2010-01-01

391

Flow-flame interactions causing acoustically coupled heat release fluctuations in a thermo-acoustically unstable gas turbine model combustor  

Microsoft Academic Search

A detailed analysis of the flow-flame interactions associated with acoustically coupled heat-release rate fluctuations was performed for a 10 kW, CH\\/air, swirl stabilized flame in a gas turbine model combustor exhibiting self-excited thermo-acoustic oscillations at 308 Hz. High-speed stereoscopic particle image velocimetry, OH planar laser induced fluorescence, and OH* chemiluminescence measurements were performed at a sustained repetition rate of 5

A. M. Steinberg; I. Boxx; M. Stoehr; W. Meier; C. D. Carter

2010-01-01

392

Acoustic calibration apparatus for calibrating plethysmographic acoustic pressure sensors  

NASA Technical Reports Server (NTRS)

An apparatus for calibrating an acoustic sensor is described. The apparatus includes a transmission material having an acoustic impedance approximately matching the acoustic impedance of the actual acoustic medium existing when the acoustic sensor is applied in actual in-service conditions. An elastic container holds the transmission material. A first sensor is coupled to the container at a first location on the container and a second sensor coupled to the container at a second location on the container, the second location being different from the first location. A sound producing device is coupled to the container and transmits acoustic signals inside the container.

Zuckerwar, Allan J. (inventor); Davis, David C. (inventor)

1995-01-01

393

3475 J. Acoust. Soc. Am., Vol. 133, No. 5, Pt. 2, May 2013 ICA 2013 Montral 3475 ACOUSTICAL SOCIETY OF AMERICA  

E-print Network

, which focused on the study of sonolumi- nescence using image-intensified cameras. Alan Walton, Tim bubbles, and single articles on bubble radiation stress, bubble injection dynamics, and acoustic bubble (ISVR) of the University of Southampton, where he served as a Lecturer in Underwater Acoustics. He has

Sóbester, András

394

Isl1 and Pou4f2 Form a Complex to Regulate Target Genes in Developing Retinal Ganglion Cells  

PubMed Central

Precise regulation of gene expression during biological processes, including development, is often achieved by combinatorial action of multiple transcription factors. The mechanisms by which these factors collaborate are largely not known. We have shown previously that Isl1, a Lim-Homeodomain transcription factor, and Pou4f2, a class IV POU domain transcription factor, co-regulate a set of genes required for retinal ganglion cell (RGC) differentiation. Here we further explore how these two factors interact to precisely regulate gene expression during RGC development. By GST pulldown assays, co-immunoprecipitation, and electrophoretic mobility shift assays, we show that Isl1 and Pou4f2 form a complex in vitro and in vivo, and identify the domains within these two proteins that are responsible for this interaction. By luciferase assay, in situ hybridization, and RNA-seq, we further demonstrate that the two factors contribute quantitatively to gene expression in the developing RGCs. Although each factor alone can activate gene expression, both factors are required to achieve optimal expression levels. Finally, we discover that Isl1 and Pou4f2 can interact with other POU and Lim-Homeodomain factors respectively, indicating the interactions between these two classes of transcription factors are prevalent in development and other biological processes. PMID:24643061

Li, Renzhong; Wu, Fuguo; Ruonala, Raili; Sapkota, Darshan; Hu, Zihua; Mu, Xiuqian

2014-01-01

395

Isl1 and Pou4f2 form a complex to regulate target genes in developing retinal ganglion cells.  

PubMed

Precise regulation of gene expression during biological processes, including development, is often achieved by combinatorial action of multiple transcription factors. The mechanisms by which these factors collaborate are largely not known. We have shown previously that Isl1, a Lim-Homeodomain transcription factor, and Pou4f2, a class IV POU domain transcription factor, co-regulate a set of genes required for retinal ganglion cell (RGC) differentiation. Here we further explore how these two factors interact to precisely regulate gene expression during RGC development. By GST pulldown assays, co-immunoprecipitation, and electrophoretic mobility shift assays, we show that Isl1 and Pou4f2 form a complex in vitro and in vivo, and identify the domains within these two proteins that are responsible for this interaction. By luciferase assay, in situ hybridization, and RNA-seq, we further demonstrate that the two factors contribute quantitatively to gene expression in the developing RGCs. Although each factor alone can activate gene expression, both factors are required to achieve optimal expression levels. Finally, we discover that Isl1 and Pou4f2 can interact with other POU and Lim-Homeodomain factors respectively, indicating the interactions between these two classes of transcription factors are prevalent in development and other biological processes. PMID:24643061

Li, Renzhong; Wu, Fuguo; Ruonala, Raili; Sapkota, Darshan; Hu, Zihua; Mu, Xiuqian

2014-01-01

396

Synthesis and enhanced electrochemical performance of Li2CoPO4F cathodes under high current cycling.  

PubMed

Lithium cobalt fluorophosphate, Li(2)CoPO(4)F, is successfully synthesized by a solid state reaction under Ar flow at 700 °C. X-ray diffraction and scanning electron microscopic studies are utilized to analyze the structural and morphological features of the synthesized materials, respectively. The presence of fluorine is also supported by energy-dispersive X-ray spectroscopy. The electrochemical properties are evaluated by means of Li/Li(2)CoPO(4)F half-cell configurations in both potentiostatic and galvanostatic modes. The Li/Li(2)CoPO(4)F cell delivers an initial discharge capacity of 132 mA h g(-1) at a current density of 0.1 mA cm(-2) between 2.0 and 5.1 V at room temperature. Due to the higher operating potential of the Co(2+/3+) couple in the fluorophosphate matrix, this cell shows a capacity retention of only 53% after 20 cycles, still the material delivered 108 mA h g(-1) at a high current rate of 1 C. Cyclic voltammetric studies corroborate the insertion and extraction of Li(+) ions by a single phase reaction mechanism during cycling. PMID:22832971

Amaresh, S; Kim, G J; Karthikeyan, K; Aravindan, V; Chung, K Y; Cho, B W; Lee, Y S

2012-09-14

397

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

NASA Astrophysics Data System (ADS)

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 Møller-Plesset perturbation theory, the coupled cluster method with single, double, and perturbative triple excitations, and the state-average complete active space self-consistent field method. The spectrum of each complex exhibits multiple band systems and is assigned to ionization of several low-energy electronic states of the neutral complex. This observation is different from previous studies of M(COT) (M = Sc, Y, La, and Gd), for which a single band system was observed. The presence of the multiple low-energy electronic states is caused by the splitting of the partially filled lanthanide 4f orbitals in the ligand field, and the number of the low-energy states increases rapidly with increasing number of the metal 4f electrons. On the other hand, the 4f electrons have a small effect on the geometries and vibrational frequencies of these lanthanide complexes.

Kumari, Sudesh; Roudjane, Mourad; Hewage, Dilrukshi; Liu, Yang; Yang, Dong-Sheng

2013-04-01

398

Representations of specific acoustic patterns in the auditory cortex and hippocampus  

PubMed Central

Previous behavioural studies have shown that repeated presentation of a randomly chosen acoustic pattern leads to the unsupervised learning of some of its specific acoustic features. The objective of our study was to determine the neural substrate for the representation of freshly learnt acoustic patterns. Subjects first performed a behavioural task that resulted in the incidental learning of three different noise-like acoustic patterns. During subsequent high-resolution functional magnetic resonance imaging scanning, subjects were then exposed again to these three learnt patterns and to others that had not been learned. Multi-voxel pattern analysis was used to test if the learnt acoustic patterns could be ‘decoded’ from the patterns of activity in the auditory cortex and medial temporal lobe. We found that activity in planum temporale and the hippocampus reliably distinguished between the learnt acoustic patterns. Our results demonstrate that these structures are involved in the neural representation of specific acoustic patterns after they have been learnt. PMID:25100695

Kumar, Sukhbinder; Bonnici, Heidi M.; Teki, Sundeep; Agus, Trevor R.; Pressnitzer, Daniel; Maguire, Eleanor A.; Griffiths, Timothy D.

2014-01-01

399

Volumetric Acoustic Vector Intensity Probe  

NASA Technical Reports Server (NTRS)

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.

Klos, Jacob

2006-01-01

400

Millimeter Waves: Acoustic and Electromagnetic  

PubMed Central

This article is the presentation I gave at the D'Arsonval Award Ceremony on June 14, 2011 at the Bioelectromagnetics Society Annual Meeting in Halifax, Nova Scotia. It summarizes my research activities in acoustic and electromagnetic millimeter waves over the past 47 years. My earliest research involved acoustic millimeter waves, with a special interest in diagnostic ultrasound imaging and its safety. For the last 21 years my research expanded to include electromagnetic millimeter waves, with a special interest in the mechanisms underlying millimeter wave therapy. Millimeter wave therapy has been widely used in the former Soviet Union with great reported success for many diseases, but is virtually unknown to Western physicians. I and the very capable members of my laboratory were able to demonstrate that the local exposure of skin to low intensity millimeter waves caused the release of endogenous opioids, and the transport of these agents by blood flow to all parts of the body resulted in pain relief and other beneficial effects. PMID:22926874

Ziskin, Marvin C.

2012-01-01

401

The Apolipoprotein-AI Mimetic Peptide L4F at a Modest Dose Does Not Attenuate Weight Gain, Inflammation, or Atherosclerosis in LDLR-Null Mice  

PubMed Central

Objective High density lipoprotein (HDL) cholesterol levels are inversely related to cardiovascular disease risk and associated with a reduced risk of type 2 diabetes. Apolipoprotein A-I (apoA-I; major HDL protein) mimetics have been reported to reduce atherosclerosis and decrease adiposity. This study investigated the effect of L4F mimetic peptide and apoA-I overexpression on weight gain, insulin resistance, and atherosclerosis in an LDL receptor deficient (Ldlr-/-) model fed a high fat high sucrose with cholesterol (HFHSC) diet. Methods Studies in differentiated 3T3-L1 adipocytes tested whether L4F could inhibit palmitate-induced adipocyte inflammation. In vivo studies used male Ldlr-/- mice fed a HFHSC diet for 12 weeks and were injected daily with L4F (100 µg/mouse) subcutaneously during the last 8 weeks. Wild-type and apoA-I overexpressing Ldlr-/- mice were fed HFHSC diet for 16 weeks. Results Neither L4F administration nor apoA-I overexpression affected weight gain, total plasma cholesterol or triglycerides in our studies. While pre-treatment of 3T3-L1 adipocytes with either L4F or HDL abolished palmitate-induced cytokine expression in vitro, L4F treatment did not affect circulating or adipose tissue inflammatory markers in vivo. Neither L4F administration nor apoA-I overexpression affected glucose tolerance. ApoA-I overexpression significantly reduced atherosclerotic lesion size, yet L4F treatment did not affect atherosclerosis. Conclusion Our results suggest that neither L4F (100 µg/day/mouse) nor apoA-I overexpression affects adiposity or insulin resistance in this model. We also were unable to confirm a reduction in atherosclerosis with L4F in our particular model. Further studies on the effect of apoA-I mimetics on atherosclerosis and insulin resistance in a variety of dietary contexts are warranted. PMID:25286043

Averill, Michelle M.; Kim, Eung Ju; Goodspeed, Leela; Wang, Shari; Subramanian, Savitha; Den Hartigh, Laura J.; Tang, Chongren; Ding, Yilei; Reardon, Catherine A.; Getz, Godfrey S.; Chait, Alan

2014-01-01

402

Bilateral acoustic neurofibromatosis camouflaged by corticosteroid treatment of sudden sensorineural hearing loss.  

PubMed

We report a case of bilateral acoustic neurofibromatosis which presented with the atypical symptom of sudden sensorineural deafness. Following corticosteroid therapy the hearing loss returned to near normal levels. The pathogenesis of reversible sudden sensorineural hearing loss in the presence of an acoustic neuroma is discussed. The importance of Gadolinium-enhanced magnetic resonance imaging in the detection of bilateral acoustic neurofibromatosis is highlighted by the case report. PMID:8824013

Gaffney, R J; McShane, D P

1996-01-01

403

ACOUSTICS IN ARCHITECTURAL DESIGN, AN ANNOTATED BIBLIOGRAPHY ON ARCHITECTURAL ACOUSTICS.  

ERIC Educational Resources Information Center

THE PURPOSE OF THIS ANNOTATED BIBLIOGRAPHY ON ARCHITECTURAL ACOUSTICS WAS--(1) TO COMPILE A CLASSIFIED BIBLIOGRAPHY, INCLUDING MOST OF THOSE PUBLICATIONS ON ARCHITECTURAL ACOUSTICS, PUBLISHED IN ENGLISH, FRENCH, AND GERMAN WHICH CAN SUPPLY A USEFUL AND UP-TO-DATE SOURCE OF INFORMATION FOR THOSE ENCOUNTERING ANY ARCHITECTURAL-ACOUSTIC DESIGN…

DOELLE, LESLIE L.

404

Acoustic response from adherent targeted contrast agents  

PubMed Central

In ultrasonic molecular imaging, encapsulated micron-sized gas bubbles are tethered to a blood vessel wall by targeting ligands. A challenging problem is to detect the echoes from adherent microbubbles and distinguish them from echoes from non-adherent agents and tissue. Echoes from adherent contrast agents are observed to include a high amplitude at the fundamental frequency, and significantly different spectral shape compared with free agents (p < 0.0003). Mechanisms for the observed acoustical difference and potential techniques to utilize these differences for molecular imaging are proposed. PMID:17225437

Zhao, Shukui; Kruse, Dustin E.; Ferrara, Katherine W.; Dayton, Paul A.

2006-01-01

405

Zooplankton size and distribution within mesoscale structures in the Mozambique Channel: A comparative approach using the TAPS acoustic profiler, a multiple net sampler and ZooScan image analysis  

NASA Astrophysics Data System (ADS)

Two surveys were conducted in the Mozambique Channel in November 2009 and April/May 2010 to study the influence of mesoscale eddies on the zooplanktonic component of the ecosystem. Three complementary methods were used to sample zooplankton: (1) hydro-acoustics with a TAPS™ multi-frequency zooplankton profiler; (2) in situ biological sampling using a Multinet with samples processed via the classical settled biovolume technique; (3) ZooScan image analysis which determines biovolume, size and taxonomic composition. This approach presented an ideal opportunity to compare the results of these different methods which highlighted a large overlap in their detectable size range. Each method favoured a particular size fraction of the population, i.e. TAPS for the microzooplankton (<0.1 mm ESR) and the Multinet and ZooScan for larger sizes (>3 mm ESR). In the case of the 2009 cruise, a well-established cyclone-anticyclone dipole was sampled, with results clearly indicating a higher concentration of zooplankton in the cyclonic eddy compared to the anticyclonic counterpart. The TAPS also detected high surface (0-22 m) concentrations of what appeared to be microzooplankton or marine snow in the cyclone. In 2010, the eddy field was less defined and more spatially variable compared to that in 2009. Two cyclonic and anticyclonic features were sampled during the cruise, each with different life histories and levels of stability. Results were inconsistent compared to those of 2009 and dependent on the size component of the population, with both cyclonic and anticyclonic features capable of having higher planktonic biomass. Differences in species composition between these mesoscale features were not too different and mainly a matter of relative biovolume. Less well formed eddy fields, particularly in the mid-Mozambique Channel, therefore appear to result in indistinct vertical and horizontal zooplankton distribution patterns.

Lebourges-Dhaussy, A.; Huggett, J.; Ockhuis, S.; Roudaut, G.; Josse, E.; Verheye, H.

2014-02-01

406

Acoustic and seismic imaging of the Adra Fault (NE Alboran Sea): in search of the source of the 1910 Adra earthquake  

NASA Astrophysics Data System (ADS)

Recently acquired swath-bathymetry data and high-resolution seismic reflection profiles offshore Adra (Almería, Spain) reveal the surficial expression of a NW-SE trending 20 km-long fault, which we termed the Adra Fault. Seismic imaging across the structure depicts a sub-vertical fault reaching the seafloor surface and slightly dipping to the NE showing an along-axis structural variability. Our new data suggest normal displacement of the uppermost units with probably a lateral component. Radiocarbon dating of a gravity core located in the area indicates that seafloor sediments are of Holocene age, suggesting present-day tectonic activity. The NE Alboran Sea area is characterized by significant low-magnitude earthquakes and by historical records of moderate magnitude, such as the Mw = 6.1 1910 Adra Earthquake. The location, dimension and kinematics of the Adra Fault agree with the fault solution and magnitude of the 1910 Adra Earthquake, whose moment tensor analysis indicates normal-dextral motion. The fault seismic parameters indicate that the Adra Fault is a potential source of large magnitude (Mw ? 6.5) earthquakes, which represents an unreported seismic hazard for the neighbouring coastal areas.

Gràcia, E.; Bartolome, R.; Lo Iacono, C.; Moreno, X.; Stich, D.; Martínez-Diaz, J. J.; Bozzano, G.; Martínez-Loriente, S.; Perea, H.; Diez, S.; Masana, E.; Dañobeitia, J. J.; Tello, O.; Sanz, J. L.; Carreño, E.; Event-Shelf Team

2012-11-01

407

Autonomous adaptive acoustic relay positioning  

E-print Network

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 ...

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

2013-01-01

408

Acoustic emission, principles and instrumentation  

Microsoft Academic Search

This is a tutorial paper. It first covers the general physical principles encountered in the field of acoustic emission. It then discusses different types of instrumentation and signal analysis techniques used with signal channel acoustic emission tests.

Beattie

1983-01-01

409

Post Treatment of Acoustic Neuroma  

MedlinePLUS

... Board of Directors Medical Advisory Board News ANA Annual Report Acoustic Neuroma Legacy Society Join/Renew Donate ANA ... Board of Directors Medical Advisory Board News ANA Annual Report Acoustic Neuroma Legacy Society Search ANAUSA.org Post- ...

410

Evidence for variation in the optimal translation initiation complex: plant eIF4B, eIF4F, and eIF(iso)4F differentially promote translation of mRNAs.  

PubMed

Eukaryotic initiation factor (eIF) 4B is known to interact with multiple initiation factors, mRNA, rRNA, and poly(A) binding protein (PABP). To gain a better understanding of the function of eIF4B, the two isoforms from Arabidopsis (Arabidopsis thaliana) were expressed and analyzed using biophysical and biochemical methods. Plant eIF4B was found by ultracentrifugation and light scattering analysis to most likely be a monomer with an extended structure. An extended structure would facilitate the multiple interactions of eIF4B with mRNA as well as other initiation factors (eIF4A, eIF4G, PABP, and eIF3). Eight mRNAs, barley (Hordeum vulgare) alpha-amylase mRNA, rabbit beta-hemoglobin mRNA, Arabidopsis heat shock protein 21 (HSP21) mRNA, oat (Avena sativa) globulin, wheat (Triticum aestivum) germin, maize (Zea mays) alcohol dehydrogenase, satellite tobacco necrosis virus RNA, and alfalfa mosaic virus (AMV) 4, were used in wheat germ in vitro translation assays to measure their dependence on eIF4B and eIF4F isoforms. The two Arabidopsis eIF4B isoforms, as well as native and recombinant wheat eIF4B, showed similar responses in the translation assay. AMV RNA 4 and Arabidopsis HSP21 showed only a slight dependence on the presence of eIF4B isoforms, whereas rabbit beta-hemoglobin mRNA and wheat germin mRNA showed modest dependence. Barley alpha-amylase, oat globulin, and satellite tobacco necrosis virus RNA displayed the strongest dependence on eIF4B. These results suggest that eIF4B has some effects on mRNA discrimination during initiation of translation. Barley alpha-amylase, oat globulin, and rabbit beta-hemoglobin mRNA showed the highest activity with eIF4F, whereas Arabidopsis HSP21 and AMV RNA 4 used both eIF4F and eIF(iso)4F equally well. These results suggest that differential or optimal translation of mRNAs may require initiation complexes composed of specific isoforms of initiation factor gene products. Thus, individual mRNAs or classes of mRNAs may respond to the relative abundance of a particular initiation factor(s), which in turn may affect the amount of protein translated. It is likely that optimal multifactor initiation complexes exist that allow for optimal translation of mRNAs under a variety of cellular conditions. PMID:19493973

Mayberry, Laura K; Allen, M Leah; Dennis, Michael D; Browning, Karen S

2009-08-01

411

Three-dimensional Ultrathin Planar Lenses by Acoustic Metamaterials  

NASA Astrophysics Data System (ADS)

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.

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

2014-10-01

412

Acoustic droplet vaporization is initiated by superharmonic focusing  

PubMed Central

Acoustically sensitive emulsion droplets composed of a liquid perfluorocarbon have the potential to be a highly efficient system for local drug delivery, embolotherapy, or for tumor imaging. The physical mechanisms underlying the acoustic activation of these phase-change emulsions into a bubbly dispersion, termed acoustic droplet vaporization, have not been well understood. The droplets have a very high activation threshold; its frequency dependence does not comply with homogeneous nucleation theory and localized nucleation spots have been observed. Here we show that acoustic droplet vaporization is initiated by a combination of two phenomena: highly nonlinear distortion of the acoustic wave before it hits the droplet and focusing of the distorted wave by the droplet itself. At high excitation pressures, nonlinear distortion causes significant superharmonics with wavelengths of the order of the droplet size. These superharmonics strongly contribute to the focusing effect; therefore, the proposed mechanism also explains the observed pressure thresholding effect. Our interpretation is validated with experimental data captured with an ultrahigh-speed camera on the positions of the nucleation spots, where we find excellent agreement with the theoretical prediction. Moreover, the presented mechanism explains the hitherto counterintuitive dependence of the nucleation threshold on the ultrasound frequency. The physical insight allows for the optimization of acoustic droplet vaporization for therapeutic applications, in particular with respect to the acoustic pressures required for activation, thereby minimizing the negative bioeffects associated with the use of high-intensity ultrasound. PMID:24449879

Shpak, Oleksandr; Verweij, Martin; Vos, Hendrik J.; de Jong, Nico; Lohse, Detlef; Versluis, Michel

2014-01-01

413

Acoustic levitator for containerless measurements on low temperature liquids  

SciTech Connect

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.

Benmore, Chris J [Argonne National Laboratory (ANL); Weber, Richard [Argonne National Laboratory (ANL); Neuefeind, Joerg C [ORNL; Rey, Charles A A [Charles Ray, Inc.

2009-01-01

414

Acoustic levitator for structure measurements on low temperature liquid droplets.  

PubMed

A single-axis acoustic levitator was constructed and used to levitate liquid and solid drops of 1-3 mm in diameter at temperatures in the range -40 to +40 degrees C. The levitator comprised (i) two acoustic transducers mounted on a rigid vertical support that was bolted to an optical breadboard, (ii) an 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 1 kHz, (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 approximately 22 kHz and could produce sound pressure levels of up to 160 dB. The force applied by the acoustic field could be modulated 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. PMID:19725664

Weber, J K R; Rey, C A; Neuefeind, J; Benmore, C J

2009-08-01

415

Three-dimensional ultrathin planar lenses by acoustic metamaterials.  

PubMed

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

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

2014-01-01

416

Three-dimensional Ultrathin Planar Lenses by Acoustic Metamaterials  

PubMed Central

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

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

2014-01-01

417

BBN and structural acoustics  

NASA Astrophysics Data System (ADS)

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.

Lyon, Richard H.

2001-05-01

418

Surface Acoustic Wave Microfluidics  

NASA Astrophysics Data System (ADS)

Fluid manipulations at the microscale and beyond are powerfully enabled through the use of 10-1,000-MHz acoustic waves. A superior alternative in many cases to other microfluidic actuation techniques, such high-frequency acoustics is almost universally produced by surface acoustic wave devices that employ electromechanical transduction in wafer-scale or thin-film piezoelectric media to generate the kinetic energy needed to transport and manipulate fluids placed in adjacent microfluidic structures. These waves are responsible for a diverse range of complex fluid transport phenomena - from interfacial fluid vibration and drop and confined fluid transport to jetting and atomization - underlying a flourishing research literature spanning fundamental fluid physics to chip-scale engineering applications. We highlight some of this literature to provide the reader with a historical basis, routes for more detailed study, and an impression of the field's future directions.

Yeo, Leslie Y.; Friend, James R.

2014-01-01

419

Acoustic Levitation Containerless Processing  

NASA Technical Reports Server (NTRS)

This research program consists of the development of acoustic containerless processing systems with applications in the areas of research in material sciences, as well as the production of new materials, solid forms with novel and unusual microstructures, fusion target spheres, and improved optical fibers. Efforts have been focused on the containerless processing at high temperatures for producing new kinds of glasses. Also, some development has occurred in the areas of containerlessly supporting liquids at room temperature, with applications in studies of fluid dynamics, potential undercooling of liquids, etc. The high temperature area holds the greatest promise for producing new kinds of glasses and ceramics, new alloys, and possibly unusual structural shapes, such as very uniform hollow glass shells for fusion target applications. High temperature acoustic levitation required for containerless processing has been demonstrated in low-g environments as well as in ground-based experiments. Future activities include continued development of the signals axis acoustic levitator.

Whymark, R. R.; Rey, C. A.

1985-01-01

420

Acoustic energy shaping  

NASA Technical Reports Server (NTRS)

A suspended mass is shaped by melting all or a selected portion of the mass and applying acoustic energy in varying amounts to different portions of the mass. In one technique for forming an optical waveguide slug, a mass of oval section is suspended and only a portion along the middle of the cross-section is heated to a largely fluid consistency. Acoustic energy is applied to opposite edges of the oval mass to press the unheated opposite edge portions together so as to form bulges at the middle of the mass. In another technique for forming a ribbon of silicon for constructing solar cells, a cylindrical thread of silicon is drawn from a molten mass of silicon, and acoustic energy is applied to opposite sides of the molten thread to flatten it into a ribbon.

Wang, T. G.; Elleman, D. D. (inventors)

1977-01-01

421

Apolipoprotein A-I mimetic peptide D-4F promotes human endothelial progenitor cell proliferation, migration, adhesion though eNOS/NO pathway.  

PubMed

Circulating endothelial progenitor cells (EPCs) have a critical role in endothelial maintenance and repair. Apolipoprotein A-I mimetic peptide D-4F has been shown to posses anti-atherogenic properties via sequestration of oxidized phospholipids, induction of remodeling of high density lipoprotein and promotion of cholesterol efflux from macrophage-derived foam cells. In this study, we test the effects of D-4F on EPC biology. EPCs were isolated from the peripheral venous blood of healthy male volunteers and characterized by 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine-labeled acetylated LDL uptake and ulex europaeus agglutinin binding and flow cytometry. Cell proliferation, migration, adhesion, nitric oxide production and endothelial nitric oxide synthase (eNOS) expression in the absence and presence of D-4F or simvastatin (as a positive control), were assayed. We demonstrated that D-4F significantly enhanced EPC proliferation, migration and adhesion in a dose-dependent manner compared with vehicle. However, all of the favorable effects of D-4F on EPCs were dramatically attenuated by preincubation with NOS inhibitor L-NAME. Further, D-4F also increased nitric oxide production in culture supernatant and the levels of eNOS expression and phosphorylation. The stimulatory effects of D-4F (10 ?g/ml) on EPC biology were comparable to 0.5 ?M simvastatin. These results suggest that eNOS/NO pathway mediates the functional modulation of EPC biology in response to D-4F treatment and support the notion that the beneficial role of D-4F on EPCs may be one of the important components of its anti-atherogenic potential. PMID:21947883

Zhang, Zhengang; Qun, Jianhua; Cao, Chunmei; Wang, Jun; Li, Wei; Wu, Yong; Du, Lin; Zhao, Pei; Gong, Kaizheng

2012-04-01

422

4F2hc-silencing impairs tumorigenicity of HeLa cells via modulation of galectin-3 and ?-catenin signaling, and MMP-2 expression.  

PubMed

4F2hc is a type-II glycoprotein whose covalent-bound association with one of several described light chains yields a heterodimer mainly involved in large neutral amino acid transport. Likewise, it is well known that the heavy chain interacts with ?-integrins mediating integrin-dependent events such as survival, proliferation, migration and even transformation. 4F2hc is a ubiquitous protein whose overexpression has been related to tumor development and progression. Stable silencing of 4F2hc in HeLa cells using an artificial miRNA impairs in vivo tumorigenicity and leads to an ineffective proliferation response to mitogens. 4F2hc colocalizes with ?1-integrins and CD147, but this interaction does not occur in lipid rafts in HeLa cells. Moreover, silenced cells present defects in integrin- (FAK, Akt and ERK1/2) and hypoxia-dependent signaling, and reduced expression/activity of MMP-2. These alterations seem to be dependent on the inappropriate formation of CD147/4F2hc/?1-integrin heterocomplexes on the cell surface, arising when CD147 cannot interact with 4F2hc. Although extracellular galectin-3 accumulates due to the decrease in MMP-2 activity, galectin-3 signaling events are blocked due to an impaired interaction with 4F2hc, inducing an increased degradation of ?-catenin. Furthermore, cell motility is compromised after protein silencing, suggesting that 4F2hc is related to tumor invasion by facilitating cell motility. Therefore, here we propose a molecular mechanism by which 4F2hc participates in tumor progression, favoring first steps of epithelial-mesenchymal transition by inhibition of ?-catenin proteasomal degradation through Akt/GSK-3? signaling and enabling cell motility. PMID:23651923

Santiago-Gómez, Angélica; Barrasa, Juan I; Olmo, Nieves; Lecona, Emilio; Burghardt, Hans; Palacín, Manuel; Lizarbe, Ma Antonia; Turnay, Javier

2013-09-01

423

Enhancement by LDL of transfer of L-4F and oxidized lipids to HDL in C57BL/6J mice and human plasma  

PubMed Central

The apoA-I mimetic peptide L-4F [(Ac-D-W-F-K-A-F-Y-D-K-V-A-E-K-F-K-E-A-F-NH2) synthesized from all L-amino acids] has shown potential for the treatment of a variety of diseases. Here, we demonstrate that LDL promotes association between L-4F and HDL. A 2- to 3-fold greater association of L-4F with human HDL was observed in the presence of human LDL as compared with HDL by itself. This association further increased when LDL was supplemented with the oxidized lipid 15S-hydroxy-5Z, 8Z, 11Z, 13E-eicosatetraenoic acid (15HETE). Additionally, L-4F significantly (P = 0.02) promoted the transfer of 15HETE from LDL to HDL. The transfer of L-4F from LDL to HDL was demonstrated both in vitro and in C57BL/6J mice. L-4F, injected into C57BL/6J mice, associated rapidly with HDL and was then cleared quickly from the circulation. Similarly, L-4F loaded onto human HDL and injected into C57BL/6J mice was cleared quickly with T1/2 = 23.6 min. This was accompanied by a decline in human apoA-I with little or no effect on the mouse apoA-I. Based on these results, we propose that i) LDL promotes the association of L-4F with HDL and ii) in the presence of L-4F, oxidized lipids in LDL are rapidly transferred to HDL allowing these oxidized lipids to be acted upon by HDL-associated enzymes and/or cleared from the circulation. PMID:21804067

Meriwether, David; Imaizumi, Satoshi; Grijalva, Victor; Hough, Greg; Vakili, Ladan; Anantharamaiah, G. M.; Farias-Eisner, Robin; Navab, Mohamad; Fogelman, Alan M.; Reddy, Srinivasa T.; Shechter, Ishaiahu

2011-01-01

424

Acoustic tooth cleaner  

NASA Technical Reports Server (NTRS)

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.

Heyman, J. S. (inventor)

1982-01-01

425

Electromechanical acoustic liner  

NASA Technical Reports Server (NTRS)

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.

Sheplak, Mark (Inventor); Cattafesta, III, Louis N. (Inventor); Nishida, Toshikazu (Inventor); Horowitz, Stephen Brian (Inventor)

2007-01-01

426

Immunochemical quantification of cynomolgus CYP2J2, CYP4A and CYP4F enzymes in liver and small intestine.  

PubMed

Abstract 1.?An increasing number of studies have indicated the roles of CYP4 proteins in drug metabolism; however, CYP4 expression has not been measured in cynomolgus monkeys, an important animal species for drug metabolism studies. 2.?In this study, cynomolgus CYP4A11, CYP4F2/3, CYP4F11 and CYP4F12, along with CYP2J2, were immunoquantified using selective antibodies in 28 livers and 35 small intestines, and their content was compared with CYP1A, CYP2A, CYP2B6, CYP2C9/19, CYP2D, CYP2E1, CYP3A4 and CYP3A5, previously quantified. 3.?In livers, CYP2J2, CYP4A11, CYP4F2/3, CYP4F11 and CYP4F12, varied 1.3- to 4.3-fold, represented 11.2, 14.4,