bluuebunny/crossref_metadata_2025 huggingface dataset:
FDTD Simulations for Ultrasound Propagation in a 2-D Breast Model
Authors: Manry Charles W. , Broschat Shira L.
Published: March 2013

To increase the survival rates of patients with breast cancer, an ultrasound imaging system must detect tumors when they are small, with a diameter of 5 mm or less. This requires an understanding of how propagation of ultrasound energy is affected by the complex structure of the breast. In this paper, a Finite-Difference Time-Domain (FDTD) method is developed to simulate ultrasound propagation in a two-dimensional model of the human breast. The FDTD simulations make it possible to better understand the behavior of an ultrasound signal in the breast. For example, here the simulations are used to investigate the effect of fat lobes adjacent to the skin layer in a simple breast model. Experimental work performed at the University of Pennsylvania has shown that strong refraction caused by the fat lobes results in nulls in the forward transmitted field. This result was duplicated with the FDTD simulations, and it was shown that the effect of refraction is clearly evident for energy exiting the breast. The existence of strong refraction has a significant impact on ultrasound imaging since it implies that an imaging method based on a weak scattering assumption is unlikely to work well.
Transmit Aperture Processing for Nonlinear Contrast Agent Imaging
Authors: Krishnan S. , O'Donnell M.
Published: March 2013

Nonlinear contrast agents, such as bubbles, are used in ultrasound to enhance backscatter from blood. To increase contrast between these agents and tissue, nonlinear imaging methods, such as harmonic imaging or difference frequency imaging, can be used. For these, power is transmitted at one frequency and received at a different frequency. Nonlinear imaging methods, however, suffer from reduced contrast because of signal transmitted by the array at the receive frequency that linearly reflects off tissue. In this paper, transmit aperture processing is proposed to improve contrast in nonlinear imaging by suppressing signal transmission at the desired receive frequency. A specific method, known as alternate phasing, is presented as an example of this approach. Simulation results show that alternate phasing greatly improves contrast between tissue and bubbles. Alternate phasing
Doppler Ultrasound Simulation Model for Pulsatile Flow with Nonaxial Components
Authors: Oung Harry , Forsberg Flemming
Published: March 2013

A numerical model that can produce pulsed Doppler signals for nonaxial, pulsatile flow is presented. The model takes into account both hemodynamic and acoustic factors that affect the Doppler signal, such that a wide range of flow patterns and arbitrary transducer types can be simulated. The physics of blood flow is modeled by solving the Navier-Stokes equations utilizing a finite element technique, and the acoustic field is modeled using the acoustic impulse response method. The model was validated by comparison to the Womersley theory. The median deviation was 3.45%. Doppler signals from flow through a 50% stenosis were also simulated. The calculated spectra demonstrated the changing flow patterns from jets and vortices. This new computer model can be used to test spectral analysis tools on simulated Doppler signals, whose underlying flow patterns are of clinical importance.
Strain Imaging of Coronary Arteries with Intraluminal Ultrasound: Experiments on an Inhomogeneous Phantom
Authors: Shapo B. M. , Crowe J. R. , Erkamp R. , Emelianov S. Y. , Eberle M. J. , O'Donnell M.
Published: March 2013

In coronary arteries, knowing the relative stiffness of atherosclerotic lesions can help physicians select the most appropriate therapeutic modality. Because soft material supports larger strains than hard, measurements of this quantity can distinguish tissue of differing stiffness. In a previous paper, we described techniques for computing displacements and strains in coronary arteries using an integrated angioplasty and imaging catheter. Here, we demonstrate that hard and soft materials in a tissue-mimicking phantom can be differentiated with this device. Because tissue motion cannot be distinguished from catheter motion a priori, we perform all computations in the coordinate system centered at the balloon's geometric center. This reference frame depends only on balloon shape and is independent of catheter motion. A specialized correlation-based, phase-sensitive speckle tracking algorithm has been developed to compute strain. Maximum phantom displacement was about 25 μm, and the maximum radial, normal strain was about 1.5 percent.
Performance Optimization in Elastography: Multicompression with Temporal Stretching
Authors: Varghese Tomy , Ophir Jonathan
Published: March 2013

A general theoretical framework known as the strain filter has been previously used to evaluate the performance in elastography. The strain filter describes the relationship among the resolution, dynamic range, sensitivity and elastographic SNR (SNR,.), and may be plotted as a graph of the upper bound of the SNRe vs. the strain experienced by the tissue, for a desired elastographic axial resolution as determined by the data window length. The ideal strain filter has an infinitely high, flat all-pass characteristic shape in the strain domain, which means that all local tissue strains are displayed in the elastogram with infinite SNRe; it also means that the strain dynamic range in the elastogram is infinite as well. Practical strain filters obtained using a single tissue compression have a bandpass characteristic shape in the strain domain, where the −3 dB width of this bandpass characteristic may be defined as the elastographic dynamic range. In this paper, we present an optimal technique for stretching multicompression elastography, practiced by selecting the optimum incremental applied strain using the strain filter. Two techniques, temporal stretching and multicompression elastography, are combined in this paper to improve elastogram quality. Stretching multicompression elastography using the optimal applied strain increment alters the shape of the strain filter from its bandpass characteristic to a more desirable high-emphasis filter. The dynamic range of optimal stretching multicompression elastography is limited only by tissue nonlinearities. This optimal applied strain increment minimizes signal decorrelation and achieves the maximum achievable elastographic SNRe.
Ultrasound Tissue Characterization of Breast Biopsy Specimens: Expanded Study
Authors: Mortensen C. L. , Edmonds P. D. , Gorfu Y. , Hill J. R. , Jensen J. F. , Schattner P. , Shifrin L. A. , Valdes A. D. , Jeffrey S. S. , Esserman L. J.
Published: March 2013

Tissue classification by examining sets of ultrasound parameters is an elusive goal. We report analysis of measurements of ultrasound speed, attenuation and backscatter in the range 3 to 8 MHz in breast tissues at 37 C. Statistical discriminant analysis and neural net analysis were employed. Data were acquired from 24 biopsy and 7 mastectomy specimens. Best separation of the classes normal, benign, and malignant occurred in the 18 cases where two tissue classes were present in the same specimen and parameters were corrected for within-patient mean; then 85–90% of cases in test sets were correctly classified. Most errors comprised misclassified benign cases. The neural net was comparable to discriminant analysis and slightly superior in separating normal and malignant classes.
Ultrasonic Measurement of Differential Displacement and Strain in a Vascular Model
Authors: Ryan L.K. , Foster F.S.
Published: March 2013

The potential of intravascular ultrasound imaging for characterizing regional arterial elasticity was examined in an experimental tissue-equivalent vessel model. Differential intrawall displacement measurement, the first step in regional elasticity determination, was investigated using a crosscorrelation tracking algorithm. Calibration studies showed that tracking accuracy varied significantly with tracking direction (axial versus lateral) and position in the field of the transducer. Midfield geometric error in the axial direction for a nominal displacement of 100 μm was 5.5 μm whereas the corresponding error in the lateral direction was 31.7 μm. Displacement was tracked in serial intravascular images of vessel phantoms acquired during stepwise pressurization experiments from 0–250 mmHg. Two-dimensional grey scale maps of axial, lateral and net intrawall displacement components over the full pressurization range were generated. Displacement profiles demonstrated successful detection of differential radial displacement and good correlation with theoretical profiles (root mean square difference 3%). The corresponding experimental strain profiles were significantly noisier (root mean square difference 76%) due to small fluctuations in the displacement data. This work demonstrates that, with further refinement, regional strain mapping in vessel walls with intravascular ultrasound imaging is feasible. Mechanical characterization of arteries may provide a new tool to aid in assessing and treating atherosclerotic lesions.
Improved Signal-to-Noise Ratio in Hybrid 2-D Arrays: Experimental Confirmation
Authors: Emery Charles D. , Smith Stephen W.
Published: March 2013

2-D array transducers have shown significant promise for medical ultrasound over conventional linear arrays, at the cost of increasing the number of channels, difficulty of fabrication and array element impedance. The increase in element impedance reduces the power coupled to a 2-D array element from a conventional 50 Ω source in transmit mode. If the array is sparse, which is typical of 2-D arrays, then the net power coupled into the front acoustic load is reduced when compared to a fully sampled aperture. Furthermore, the received signal-to-noise ratio (SNR), when measured through a nonideal amplifier, is degraded because the high impedance 2-D array transducer element cannot efficiently drive the coaxial cable. The reduction in transmit sensitivity and received SNR can be circumvented with the application of multilayer piezoelectric elements. The improvement in transmit occurs because the transducer impedance is better matched to the impedance of the source. In receive, multilayer elements allow more of the open circuit received voltage to fall across the input of the high impedance preamplifier. In this case, the same number of layers are used in transmit and receive. Recently, it has been suggested that separate optimization of the transmit channel and receive channel (a hybrid array) would further improve the pulse-echo SNR. In this paper, we fabricated and tested a hybrid array operating at 1 MHz using a multilayer transmit element and single layer receive element. A 7 Ω transmitter and high impedance preamplifier were placed adjacent to the transmit and receive elements within the transducer assembly. The hybrid pulse-echo SNR improved by 26.4 dB over the conventional array. The experimental result showed good agreement with the KLM model. Furthermore, KLM simulations showed that as the operating frequency of the array increases, the overall improvement over the conventional array increases. For example, a 1.5-D array operating at 2 MHz had an improvement of 30 dB whereas a 7.5 MHz 1.5-D array showed an increase of approximately 38 dB. The separate optimization of the transmit and receive channel for 2-D arrays showed even greater improvement than for 1.5-D arrays. For example, a 2 MHz 2-D array had an improvement of over 44 dB.
Elastic and Acoustic Properties of Vessel Mimicking Material for Elasticity Imaging
Authors: de Korte C.L. , Céspedes E.I. , van der Steen A.F.W. , Norder B. , te Nijenhuis K.
Published: March 2013

The mechanical and acoustic properties of agar-gelatin gels, used to construct vessel mimicking phantoms for ultrasonic elasticity studies, were investigated. Gels with varying compression moduli were made using a gelatin solution (8% by weight) with a variable amount of agar(1%-3% by weight). Carborundum particles were added as scattering material.

The compression modulus was determined using a dynamic mechanical analyzer. The dependence of the compression modulus and the acoustic parameters on the agar concentration, as well as on the age and the temperature of the samples, was investigated. The results show that the compression modulus is strongly influenced by these factors, while the effect on the acoustic parameters is less.

Compression moduli spanning a useful range for vascular phantom construction with realistic acoustic parameters can be achieved by varying the amount of agar. Phantoms constructed from these gels are well suited to serve as a model for plaque containing vessels.
A Two-Dimensional Array for B-Mode and Volumetric Imaging with Multiplexed Electrostrictive Elements
Authors: Davidsen Richard E. , Smith Stephen W.
Published: March 2013

A 2:1 multiplexed 2-D array has been developed that has a sparse element pattern designed for real time volumetric imaging and an alternate element pattern designed for B-mode imaging. For volumetric imaging, a small aperture was used to provide a wide transmit beam, allowing multiple beams to be received simultaneously. For B-mode imaging, a larger aperture with a more narrow transmit beam was used to improve image quality. Sparse random element patterns were evaluated by beamplot and cyst image simulations. Using the alternate element pattern for B-mode imaging, simulated cyst contrast was improved by 28%. The multiplexed transducer was fabricated using an electrostrictive material in which array elements were activated and deactivated by a dc bias field. The transducer had a 3.4 MHz center frequency with 46% bandwidth, which was consistent with KLM simulations. The high dielectric constant of the electrostrictive material resulted in an element clamped capacitance of 14.3 pF versus 2 pF for a convention PZT element. An output off isolation of −35 dB was measured for transmit and −61 dB for receive. The array was integrated with the volumetric scanner and used to make real time images of a cyst phantom. The images showed improved cyst contrast using the alternate aperture for B-mode imaging.
Spatial Compounding in 3D Imaging of Limbs
Authors: He Ping
Published: March 2013

Effects of spatial compounding on image resolution and speckle noise are studied. Using computer simulation, it is shown that spatial compounding using averaged reconstruction can significantly improve lateral resolution while slightly deteriorate axial resolution. The amount of net resolution improvement depends mainly on the compound angle, but is insensitive to the number of component images used in compounding. While the fact that spatial compounding can effectively reduce speckle noise is well known, the analysis in this paper indicates that to maximize speckle reduction, the component echo amplitudes must meet two conditions: to be mutually independent and to have the same mean power. These findings provide useful guidelines for the analysis and optimization of the performance of an ultrasound scanning system that has been specially developed for imaging residual limbs.
Spectral Analysis of Demodulated Ultrasound Returns: Detection of Scatterer Periodicity and Application to Tissue Classification
Authors: Roth Scott L. , Hastings Harold M. , Evans Steven J.L. , Esposito Michael , Gladstone Clifford , Rathod Sharad , Bodenheimer Monty M.
Published: March 2013

Ultrasound returns from tissue display variations in amplitude on several spatial scales. Although large-scale variations result from factors such as attenuation, variations on smaller scales are caused by tissue characteristics such as variations in scatterer spacing and reflectance. These small scale variations cause a corresponding variation in the amplitude of the ultrasound return. A simple and direct method for detecting and quantifying periodicity in these variations in the presence of attenuation is described. The radiofrequency ultrasound return is first demodulated by full-wave rectification. The normalized power spectrum of the demodulated return then yields an index that we call the relative Fourier energy.

Both computer simulations and in vitro experiments were performed in order to study how relative Fourier energy performed in discriminating between periodic and random scatterer distributions. Computer simulations demonstrated significant differences between the returns from periodic and random scatterer distributions. Ultrasound returns from aortic tissue yielded a relative Fourier energy index that was significantly different between normal vs. atherosclerotic tissue (normal: 0.868 ± 0.076, mean ± s.d., fibrofatty plaque: 0.705 ±0.109, p< 0.01 vs. normal, calcified plaque: 0.753 ± 0.078, p < 0.01 vs. normal). In contrast, no difference was found in comparisons of overall reflectance.

SUMMARY
High Resolution Low Frequency Ultrasonic Tomography
Authors: Lasaygues P. , Lefebvre J.P. , Mensah S.
Published: March 2013

Ultrasonic reflection tomography results from a linearization of the inverse acoustic scattering problem, named the inverse Born approximation. The goal of ultrasonic reflection tomography is to obtain reflectivity images from backscattered measurements. This is a Fourier synthesis problem and the first step is to correctly cover the frequency space of the object. For this inverse problem, we use the classical algorithm of tomographic reconstruction by summation of filtered backprojections. In practice, only a limited number of views are available with our mechanical rig, typically 180, and the frequency bandwidth of the pulses is very limited, typically one octave. The resolving power of the system is then limited by the bandwidth of the pulse. Low and high frequencies can be restored by use of a deconvolution algorithm that enhances resolution. We used a deconvolution technique based on the Papoulis method. The advantage of this technique is conservation of the overall frequency information content of the signals. The enhancement procedure was tested by imaging a square aluminium rod with a cross-section less than the wavelength. In this application, the central frequency of the transducer was 250 kHz so that the central wavelength was 6 mm whereas the cross-section of the rod was 4 mm. Although the Born approximation was not theoretically valid in this case (high contrast), a good reconstruction was obtained.
Progress in Two-Dimensional Arrays for Real-Time Volumetric Imaging
Authors: Light E. D. , Davidsen R. E. , Fiering J.O. , Hruschka T. A. , Smith S. W.
Published: March 2013

The design, fabrication, and evaluation of two dimensional array transducers for real-time volumetric imaging are described. The transducers we have previously described operated at frequencies below 3 MHz and were unwieldy to the operator because of the interconnect schemes used in connecting to the transducer handle. Several new transducers have been developed using new connection technology. A 40 × 40 = 1,600 element, 3.5 MHz array was fabricated with 256 transmit and 256 receive elements. A 60 × 60 = 3,600 element 5.0 MHz array was constructed with 248 transmit and 256 receive elements. An 80 × 80 = 6,400 element, 2.5 MHz array was fabricated with 256 transmit and 208 receive elements. 2-D transducer arrays were also developed for volumetric scanning in an intracardiac catheter, a 10 × 10 = 100 element 5.0 MHz forward-looking array and an 11 × 13 = 143 element 5.0 MHz side-scanning array. The −6 dB fractional bandwidths for the different arrays varied from 50% to 63%, and the 50 Ω insertion loss for all the transducers was about −64 dB. The transducers were used to generate real-time volumetric images in phantoms and in vivo using the Duke University real time volumetric imaging system, which is capable of generating multiple planes at any desired angle and depth within the pyramidal volume.
Ultrasonic Imaging Using Optoelectronic Transmitters
Authors: Emery Charles D. , Casey H.C. , Smith Stephen W.
Published: March 2013

Conventional ultrasound scanners utilize electronic transmitters and receivers at the scanner with a separate coaxial cable connected to each transducer element in the handle. The number of transducer elements determines the size and weight of the transducer cable assembly that connects the imaging array to the scanner. 2-D arrays that allow new imaging modalities to be introduced significantly increase the channel count making the transducer cable assembly more difficult to handle. Therefore, reducing the size and increasing the flexibility of the transducer cable assembly is a concern. Fiber optics can be used to transmit signals optically and has distinct advantages over standard coaxial cable to increase flexibility and decrease the weight of the transducer cable for large channel numbers. The use of fiber optics to connect the array and the scanner entails the use of optoelectronics such as detectors and laser diodes to send and receive signals. In transmit, optoelectronics would have to be designed to produce high-voltage wide-bandwidth pulses across the transducer element. In this paper, we describe a 48 channel ultrasound system having 16 optoelectronic transmitters and 32 conventional electronic receivers. We investigated both silicon avalanche photodiodes (APD's) and GaAs lateral photoconductive semiconductor switches (PCSS's) for producing the transmit pulses. A Siemens SI-1200 scanner and a 2.25 MHz linear array were used to compare the optoelectronic system to a conventional electronic transmit system. Transmit signal results and images in tissue mimicking phantoms of cysts and tumors are provided for comparison.
Ultrasound Image Texture Analysis for Characterizing Intramuscular Fat Content of Live Beef Cattle
Authors: Kim Nam-Deuk , Amin Viren , Wilson Doyle , Rouse Gene , Udpa Satish
Published: March 2013

The primary factors in determining beef quality grades are the amount and distribution of intramuscular fat percentage (IMFAT). Texture analysis was applied to ultrasound B-mode images from ribeye muscle of live beef cattle to predict its IMFAT. We used wavelet transform (WT) for multiresolutional texture analysis and second-order statistics using a gray-level co-occurrence matrix (GLCM) technique. Sets of WT-and GLCM-based texture features were calculated from ultrasonic images from 207 animals and linear regression methods were used for IMFAT prediction. WT-based features included energy ratios, central moments of wavelet-decomposed subimages and wavelet edge density. The regression model using WT features provided a root mean square error (RMSE) of 1.44 for prediction of IMFAT using validation images, while that of GLCM features provided an RMSE of 1.90. The prediction models using the WT features showed potential for objective quality evaluation in the live animals.
Shielding of Piezoelectric Ultrasonic Probes in Hall Effect Imaging
Authors: Wen Han , Bennett Eric , Wiesler David G.
Published: March 2013

This paper addresses significant sources of electromagnetic noise in Hall effect imaging. Hall effect imaging employs large electrical pulses for signal generation and high sensitivity ultrasonic probes for signal reception. Coherent noise arises through various coupling mechanisms between the excitation pulse and the probe. In this paper, the coupling mechanisms are experimentally isolated and theoretically analyzed. Several methods of shielding the probe from electromagnetic interference are devised and tested. These methods are able to reduce the noise to levels below the random thermal noise, thereby improving the signal-to-noise ratio in HEI by two orders of magnitude.
Effective Density Estimators Based on the K Distribution: Interest of Low and Fractional Order Moments
Authors: Ossant Frédéric , Patat Frédéric , Lebertre Matthias , Teriierooiterai Marie-Laure , Pourcelot Léandre
Published: March 2013

The K distribution is an efficient model to the nonRayleigh statistics of the envelope of backscattered signals in random media. This modeling leads to estimate a parameter of effective density by means of the calculation of statistical moments of the envelope signal. In this study, we propose a mathematical analysis of an effective density estimator previously used and based on superior order moments. In order to improve the effective density estimate, we propose several estimators based on low and fractional order moments. The performances of these estimators are evaluated both with simulated signals and in an experimental context with synthetic foams. Estimators based on low and fractional moments appear to be more robust than superior moment-based estimator and an improvement of the spatial resolution of the estimate can be obtained. Results also confirm the capability of the effective density parameter to characterize the spatial distribution of scattering structures.
Ultrasonic Imaging of the Electroacoustic Effect in Macromolecular Gels
Authors: Wen Han , Balaban Robert S.
Published: March 2013

The electroacoustic effect occurs in electrolytes and colloidal suspensions. It describes the phenomenon in which a voltage applied to the sample produces an acoustic signal or vice versa. The basic mechanism is that charged particles in the sample have various mobilities due to different masses and viscosities. Under an external voltage they respond differently to the electrical force. This results in an overall acoustic vibration. The electroacoustic effect has been the basis for many measurement tools of solutions and other materials. In this note a method to image macromolecular gel samples using the electroacoustic effect at ultrasound frequencies is presented. Radiofrequency electrical excitation produces ultrasonic signal due to spatial changes in the electroacoustic sonic amplitude of the sample, which is used to construct an image similar to ultrasonography. This method is demonstrated in agar gel and eggwhite protein phantoms. The image contrast mechanism is also discussed.
Edge Detection in Ultrasound Images Based on Differential Tissue Attenuation Rates
Authors: Hammoude Andrew
Published: March 2013

Identification of the cardiac borders is a basic goal in the analysis of echocardiographic images. This is a requirement for various analysis purposes, such as the derivation of quantitative parameters, for wall motion analysis and for the creation of three-dimensional reconstructions. Border identification is usually accomplished by first identifying a set of generic edge points, then extracting the border of interest from the edge map. A variety of edge detection algorithms have been reported in the literature. However, the most commonly used methods are all based on the same underlying tissue discriminant, namely, the widely differing backscatter levels of the different types of tissue that form the cardiac borders, in particular, blood and myocardium. We have implemented a new method of edge detection based on an entirely different ultrasonic tissue characteristic — that of attenuation, the rate at which the tissue absorbs ultrasonic energy. This characteristic also differs widely between blood and myocardium, and therefore provides an alternative means of discriminating between these two types of tissue. The method searches for the abrupt change in attenuation rate that characteristically occurs at the blood/myocardium interface. At each point in the image, the average attenuation rates of the portions of tissue radially preceding and radially following the point are determined by least-squares regression. If one of these attenuation rates is sufficiently close to that of blood, and the other is sufficiently close to that of myocardium, then the point is flagged as an edge point. This paper describes how this method is implemented in software, and presents the results of applying the method to a library of sample images.
Subharmonic Imaging with Microbubble Contrast Agents: Initial Results
Authors: Shi William T. , Forsberg Flemming , Hall Anne L. , Chiao Richard Y. , Liu Ji-Bin , Miller Steve , Thomenius Kai E. , Wheatley Margaret A. , Goldberg Barry B.
Published: March 2013

The subharmonic emission from insonified contrast microbubbles was used to create a new imaging modality called Subharmonic Imaging. The subharmonic response of contrast microbubbles to ultrasound pulses was first investigated for determining adequate acoustic transmit parameters. Subharmonic A-lines and gray scale images were then obtained using a laboratory pulse-echo system in vitro and a modified ultrasound scanner in vivo. Excellent suppression of all backscattered signals other than from contrast microbubbles was achieved for subharmonic A-lines in vitro while further optimization is required for in vivo gray scale subharmonic images.
Detection of High-Intensity Focused Ultrasound Liver Lesions Using Dynamic Elastometry
Authors: Shi Xuegong , Martin Roy W. , Rouseff Daniel , Vaezy Shahram , Crum Lawrence A.
Published: March 2013

A novel ultrasound technique was developed for detecting the distribution of stiffness in biological tissue. The method, which we call ‘dynamic elastometry,’ involves applying a low-frequency vibration (≤5 Hz) to the tissue and measuring the resulting velocity pattern within the sample using Doppler spectral analysis. Based upon the velocity differences, an elastically stiff region can be differentiated from surrounding soft tissue. Dynamic elastometry was used to both detect and quantify lesions produced by high-intensity focused ultrasound (HIFU) in porcine livers. Measurements of the lesion position and length agreed well with independent geometric measurements. The mean and standard deviation of the differences between the two types of measurement were −0.01cm and 0.10 cm for lesion position, and −0.05 cm and 0.12 cm for lesion length, respectively. The relative stiffness between lesions and normal liver tissue was estimated by the velocity gradient ratio. Results were compared with the Young's modulus ratios between lesion and normal liver tissue obtained from mechanical measurement. The dynamic elastometric estimates had a strong linear correlation with the mechanical measurements ( r = 0.93) but were smaller than the latter by 26%.
Realization of Sinc Waves in Ultrasound Imaging Systems
Authors: Jeong Mok-Kun , Kwon Sung-Jae , Song Tae-Kyong , Bae Moo-Ho
Published: March 2013

It is known that the transmit pulse waveforms of a limited-diffraction beam in a linear array transducer should be varied according to transducer element location, dictating the use of sophisticated hardware. In order to overcome this disadvantage while achieving the same field response, we propose a method of synthesizing limited-diffraction beams by combined signal processing of pulsed plane waves propagating in distinct directions over several consecutive insonification time intervals. The method is capable of achieving both higher transmit power and better lateral resolution over a larger depth of field. Although its field response is not uniform throughout the imaging points, this is not a major problem since the response is quite uniform within a region of interest. The proposed method requires the use of multiple insonifications for transmit focusing, and, therefore, can be applied in imaging slowly-moving or still objects. Both simulation and experimental results corroborate its superiority in terms of the lateral resolution at all imaging depths.
Elastographic Imaging of the Normal Canine Prostate In Vitro
Authors: Kallel Faouzi , Price Roger E. , Konofagou Elisa , Ophir Jonathan
Published: March 2013

Elastography has been shown to be successful in mapping the relative mechanical attributes of normal as well as abnormal tissues. In this study, the histological characteristics of freshly excised normal canine prostates were used to explain consistently depicted elastographic features. The elastograms of the transverse cross-sections across the urethra demonstrated a consistent symmetry of the gland as well as clear anatomic structures. These include a central portion of the gland surrounding the urethra and a peripheral gland. The central gland was consistently softer than the peripheral gland. At the level of the verumontanum, depicted as a small stiff ridge, the lumen of the urethra was consistently demonstrated as an inverted soft ‘u’ or ‘v’ shaped area. The network of branching-fibrous connective tissue septa was depicted by the elastogram as linear features, which converged on the urethra. In the anterior side of the gland, the fibromuscular stroma was seen as a circumscribed hard tissue. In the sagittal view, the elastogram suggested a stiff peripheral zone surrounding a softer central zone, which is traversed by the urethra depicted as soft tissue.
Time-Resolved Pulsed Elastography with Ultrafast Ultrasonic Imaging
Authors: Sandrin L , Catheline S. , Tanter M. , Hennequin X. , Fink M.
Published: March 2013

In this paper, a new elastographic method is proposed. Using this method, the propagation of a low-frequency transient shear wave can be imaged by means of an ultrafast imaging system (up to 10,000 frames/s) that we have developed. Ultrafast ultrasonic imaging is obtained with a linear array of transducers (3.5 MHz) connected to electronics that have 64 channels sampled at 30 MHz and 128 Kbytes for storing the backscattered signals. Displacements are measured using cross-correlation of the ultrasonic signals. Movies of the low central frequency (200 Hz) shear wave propagation through homogeneous and heterogeneous phantoms have been obtained with 1,000 and 2,000 frames per second.
The role of reinforcement sensitivity in the development of childhood personality
Authors: Slobodskaya Helena R. , Kuznetsova Valeriya B.
Published: March 2013

The study examined the contribution of reinforcement sensitivity to childhood personality at three levels of the hierarchical structure, mid-level traits, the Big Five and two higher-order factors, and the moderating role of sex and age in a sample of 3–18-year-olds. The canonical correlation analyses indicated that reinforcement sensitivity and personality have more than 50% of common variance; reward and punishment sensitivities had opposing effects and were linked to both higher-order factors, Extraversion and Agreeableness, and lower-order traits Sociability and Shyness. There were no sex differences in the effects of reinforcement sensitivity, the negative effect of reward sensitivity on Alpha domain in school age was higher than in adolescence, whereas the negative effect of punishment sensitivity on Beta domain decreased from age 3–4 years to age 17–18 years.
Finding more trustworthy answers: Various trustworthiness factors in question answering
Authors: Oh Hyo-Jung , Yoon Yeo-Chan , Kim Hyun Ki
Published: March 2013

In the recent explosion of Web information, it is important to find not only appropriate, but also more trustworthy answers to user questions. This paper proposes an improved ranking model for question answering (QA) which is focused on various answer trustworthiness factors. Contrary to past research that simply focused on document quality, we have identified three different answer trustworthiness factors in multiple layers of answering processes: document quality, authority and reputation of answer sources, and appropriateness of answering method for a given question. Each of these factors is used in the answer selection as an input to the ranking scheme that can be tuned for the confidence value for a particular answer candidate. Through several experiments, we analysed the efficacy of our QA model from two points of view: indexing and answering. In indexing, distilling unreliable documents brings not only a 96% reduction in document size but also a 92% speed increase in indexing time. To reveal the effect of trustworthiness factors in answering, we conducted several experiments to determine the optimum combination of weights of sub-features for trustworthiness factors. Finally, the proposed method using all answer trustworthiness factors obtained an improvement in effectiveness over the simple routing QA by 150% in Top1. We also investigated improvement impacts according to answer trustworthiness factors.
What is Wrong with the Global Financial System?
Authors: Goodchild Philip
Published: March 2013

In the global credit crisis of 2007–08, the financial system escaped human control and became unstable, with near-catastrophic consequences. The underlying processes driving this instability may be traced to: positive feedback between asset price inflation and increasing leverage; increasing inequity leading to insufficient consumer demand; and the clash between exponential economic growth and the scarcity of primary commodities. These expose fundamental dilemmas that structure economic activity. Since credit is a newly-created contractual relation, while debt must be repaid with money, the global economy is caught in an ever-expanding spiral of debt which, when it reaches its limits, will result in default, devaluation, and inflation.
‘We are more than statistics and scattered body parts’: Telling stories and coalescing Palestinian history
Authors: Landy David
Published: March 2013

The fragmentation of Palestinian lives into exile, under occupation and within Israel has led to a complex interweaving of collective memory and individual memories in the attempt to come to terms with and represent this existence. Central to Palestinian self-understanding is the key interruptive event of the Nakba, the ethnic cleansing of Palestine in 1948 which disrupted the people’s links to the land of Palestine – not only for Palestinians in exile but also for those within present-day Israel. Memorialization practices, such as those undertaken in village memorial books which record in detail the Palestinian villages destroyed in 1948, work to foster a collectivity linked across generations and borders. However these practices also repress marginalized voices, especially the voices, experiences and perspectives of women. By highlighting these voices, by engaging in collecting memories and by critically assessing the process of collective memorialization, the authors reviewed present a decentred, complex and kaleidoscopic version of Palestinian self-understanding and identity.
Health justice and capabilities: A turning point for global health?
Authors: Khoo Su-ming
Published: March 2013

This essay discusses two important recent books on health justice and makes the case for their relevance to global health and to social and political mobilization for health reform. Health and Social Justice (Ruger, 2010) and Health Justice (Venkatapuram, 2011) approach theories of capabilities and justice as the substantive ground of human health. They substantiate and more fully specify the capabilities paradigm, its shared basis with health rights and its relevance to health reforms and the growing global health justice movement. The recent turning point for global health invites a meeting point with the capabilities paradigm. The capabilities approach offers conceptual and practical potential for ‘global health’, linking normative, substantive and procedural claims for health justice and health rights.
Art, Fashion, and Anti-consumption
Authors: Biehl-Missal Brigitte
Published: March 2013

Contemporary artists deal with many forms of social interaction, including consumption. In this commentary, I walk the fine line between art and fashion, distant sisters in history. Referring to fashion projects presented at dOCUMENTA(13), I show that art’s aesthetic language may speak against fashion’s ultimate commercial meaning. The aesthetic perspective is important because reasons against consumption are not merely intellectual. They include many emotional and symbolic forms of knowing, in this case about self-degrading styling concepts that are possible only through unsustainable production by global fast fashion retailers such as H&M, Zara, and Forever 21 and other cheap fashion brands. Referring to art critics’ assessments and aesthetic theory, I interpret my observations through theories of anti-consumption. Included is a review of Elizabeth Cline’s critical book Overdressed: The Shockingly High Cost of Cheap Fashion that reveals some of the motifs of the fast fashion industry resonating in contemporary artworks and investigates opportunities to reject, resist, and reclaim fashion.
Classification of Canine Nonangiogenic, Nonlymphogenic, Gastrointestinal Sarcomas Based on Microscopic, Immunohistochemical, and Molecular Characteristics
Authors: Hayes S. , Yuzbasiyan-Gurkan V. , Gregory-Bryson E. , Kiupel M.
Published: March 2013

Canine nonangiogenic, nonlymphogenic, gastrointestinal sarcomas have been previously diagnosed as gastrointestinal stromal tumors (GIST), leiomyosarcomas, or nonspecified spindle cell sarcomas, but diagnostic criteria for each entity are poorly defined. We propose a classification for canine nonangiogenic, nonlymphogenic, gastrointestinal sarcomas based on microscopic, immunohistochemical, and molecular characteristics. Applying the classification to 40 canine nonangiogenic, nonlymphogenic, gastrointestinal sarcomas documented its diagnostic and prognostic value. Eighteen (45%) sarcomas were classified as GIST based on positive KIT immunoreactivity. All GISTs were positive for vimentin, 14 (78%) were positive for S-100, and 6 (33%) were positive for smooth muscle actin (SMA). In contrast to their human counterparts, canine GISTs occurred mainly in the small intestine (67%) but commonly metastasized (5/18) to liver, lymph nodes, and omentum. Six GISTs had an activated KIT mutation in exon 11 of c-Kit, but no mutations were detected in exons 8, 9, 13, and 17. Twelve (30%) sarcomas were classified as leiomyosarcomas based on positive labeling for SMA and negative labeling for KIT. Four of these neoplasms were well differentiated leiomyosarcomas characterized by weak to no labeling for vimentin, and 8 were poorly differentiated leiomyosarcomas characterized by strong labeling for vimentin. None of the leiomyosarcomas metastasized, but poorly differentiated leiomyosarcomas had a higher risk of local invasion. Ten (25%) sarcomas were classified as non-GIST/nonleiomyosarcomas that were negative for KIT and SMA but positive for vimentin and either S-100 and/or PGP 9.5. These neoplasms most likely represent sarcomas of neurogenic differentiation resembling Schwann cells or perineurial or endoneurial fibroblasts, respectively.
Coexistence of Granulomatous Enteric Inflammation and Neoplasia in an Adult Sheep
Authors: Benavides J. , Garcia-Pariente C. , Garrido J. M. , Sevilla I. A. , García-Marín J. F. , Pérez V. , Ferreras M. C.
Published: March 2013

A 7-year-old dairy sheep suffering from chronic loss of weight without diarrhea or anorexia was euthanized after failing to respond to any treatment (antibiotic and antiparasitic). The main findings at the necropsy of this animal were multifocal miliary nodules in several organs, mainly in the Peyer’s patches of the small intestine, and a segmental thickening of the jejunal wall. Histologic examination of the samples taken at the necropsy showed a multifocal chronic granulomatous inflammation, with mineralization and caseous necrosis at the core of the larger granulomas and scarce intrahistiocytic acid-fast bacilli consistent with a disseminated digestive tuberculosis. Polymerase chain reaction and bacteriological culture from these samples confirmed Mycobacterium avium subsp avium to be the etiologic agent of this infection. Histologically, the cause of the segmental thickening of the jejunal wall was found to be a small intestine adenocarcinoma, which in some areas coexisted with the granulomatous lesion.
Use of Computed Tomography and Histopathologic Review for Lung Lesions Produced by the Interaction Between Mycoplasma hyopneumoniae and Fumonisin Mycotoxins in Pigs
Authors: Pósa R. , Magyar T. , Stoev S. D. , Glávits R. , Donkó T. , Repa I. , Kovács M.
Published: March 2013

Mycoplasma hyopneumoniae has a primary role in the porcine respiratory disease complex (PRDC). The objective of this study was to determine whether fumonisin mycotoxins influence the character and/or the severity of pathological processes induced in the lungs of pigs by Mycoplasma hyopneumoniae. Four groups of pigs ( n = 7/group) were used, one fed 20 ppm fumonisin B1 (FB1) from 16 days of age (group F), one only infected with M. hyopneumoniae on study day 30 (group M), and a group fed FB1 and infected with M. hyopneumoniae (group MF), along with an untreated control group (group C). Computed tomography (CT) scans of infected pigs (M and MF) on study day 44 demonstrated lesions extending to the cranial and middle or in the cranial third of the caudal lobe of the lungs. The CT images obtained on study day 58 showed similar but milder lesions in 5 animals from group M, whereas lungs from 2 pigs in group MF appeared progressively worse. The evolution of average pulmonary density calculated from combined pixel frequency values, as measured by quantitative CT, was significantly influenced by the treatment and the age of the animals. The most characteristic histopathologic lesion in FB1-treated pigs was pulmonary edema, whereas the pathomorphological changes in Mycoplasma-infected pigs were consistent with catarrhal bronchointerstitial pneumonia. FB1 aggravated the progression of infection, as demonstrated by severe illness requiring euthanasia observed in 1 pig and evidence of progressive pathology in 2 pigs (group MF) between study days 44 and 58.
Development: The Third Way
Authors: Omo-Fadaka Jimoh
Published: March 2013

The coming of independence to new nations means, besides self-government and management of resources, responsibility for the total welfare of the population as a whole and minimum disruption of the ecosystem. When options are available, what is the wisest way to development?

The problem confronting the developing countries today is poverty. This poverty is characterized by unemployment, under-employment, illiteracy, malnutrition, disease, starvation and bad housing. How is this problem to be solved? The urban way or the rural way to development? The imitation of the patterns of development of the industrialized nations or the adoption of development patterns suited to indigenous traditional and cultural conditions?

The lessons of the First United Nations Development Decade have shown quite clearly that given the pressure of time (constantly aggravated by the increase in population) the urban way to development and the imitation of the patterns of development of the industrialized nations are incapable of handling problems as complex and deep-rooted as those faced by many developing countries. What is required is the rural way to development from the bottom up (at micro-economic level) and not the urban way from top to bottom (at macro-economic level).
Lessons of the Oil Crisis for the Third World
Authors: Adam György
Published: March 2013

The author argues that the so-called oil crisis may open out a new perspective on development aid to the Third World if the oil-producing countries, instead of allowing the giant Western banks and corporations to make a grab for their petro dollars (as the Western nations had so far made a grab for incredibly cheap oil energy), decide to pool the surplus oil revenues for self-help among the Third World countries. He suggests the setting up of an interregional Third World Bank, which, unlike the existing World Bank group (typecast as the instrument of the rich market economies), would be the instrument of the developing countries, thus breaking the monopoly of the West in international financing.
Measuring World Development – II
Authors: Galtung J. , Guha A. , Wirak A. , Sjlie S. , Cifuentes M. , Goldstein H.
Published: March 2013

Having outlined in the first part of the paper the principles guiding the selection of indicators to measure development at the level of human beings, the authors proceed in this second and concluding part to present such indicators, without, however, making any claims to finality. The idea is to measure development by the size of the sufficiency group in society; that is, the proportion of the population that is enabled to satisfy its fundamental and almost fundamental needs.