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2-D Imaging of Electron Temperature in Tokamak Plasmas  

SciTech Connect

By taking advantage of recent developments in millimeter wave imaging technology, an Electron Cyclotron Emission Imaging (ECEI) instrument, capable of simultaneously measuring 128 channels of localized electron temperature over a 2-D map in the poloidal plane, has been developed for the TEXTOR tokamak. Data from the new instrument, detailing the MHD activity associated with a sawtooth crash, is presented.

T. Munsat; E. Mazzucato; H. Park; C.W. Domier; M. Johnson; N.C. Luhmann Jr.; J. Wang; Z. Xia; I.G.J. Classen; A.J.H. Donne; M.J. van de Pol



Real-Time 2-D Temperature Imaging Using Ultrasound  

PubMed Central

We have previously introduced methods for noninvasive estimation of temperature change using diagnostic ultrasound. The basic principle was validated both in vitro and in vivo by several groups worldwide. Some limitations remain, however, that have prevented these methods from being adopted in monitoring and guidance of minimally invasive thermal therapies, e.g., RF ablation and high-intensity-focused ultrasound (HIFU). In this letter, we present first results from a real-time system for 2-D imaging of temperature change using pulse-echo ultrasound. The front end of the system is a commercially available scanner equipped with a research interface, which allows the control of imaging sequence and access to the RF data in real time. A high-frame-rate 2-D RF acquisition mode, M2D, is used to capture the transients of tissue motion/deformations in response to pulsed HIFU. The M2D RF data is streamlined to the back end of the system, where a 2-D temperature imaging algorithm based on speckle tracking is implemented on a graphics processing unit. The real-time images of temperature change are computed on the same spatial and temporal grid of the M2D RF data, i.e., no decimation. Verification of the algorithm was performed by monitoring localized HIFU-induced heating of a tissue-mimicking elastography phantom. These results clearly demonstrate the repeatability and sensitivity of the algorithm. Furthermore, we present in vitro results demonstrating the possible use of this algorithm for imaging changes in tissue parameters due to HIFU-induced lesions. These results clearly demonstrate the value of the real-time data streaming and processing in monitoring, and guidance of minimally invasive thermotherapy.

Liu, Dalong; Ebbini, Emad S.



Imaging 2D turbulence  

Microsoft Academic Search

Gravity-driven flow in a soap film tunnel is spatially almost two-dimensional. A modification of particle-image velocimetry\\u000a technique produces a comprehensive quantitative description of the flow. The technique allows simultaneous acquisition of\\u000a the velocity (two components) in the plane of the film and the film thickness. The latter behaves as a scalar advected by\\u000a the flow. The visualization method developed for

P. Vorobieff; M. Rivera; R. E. Ecke



Tomosynthesis imaging with 2D scanning trajectories  

NASA Astrophysics Data System (ADS)

Tomosynthesis imaging in chest radiography provides volumetric information with the potential for improved diagnostic value when compared to the standard AP or LAT projections. In this paper we explore the image quality benefits of 2D scanning trajectories when coupled with advanced image reconstruction approaches. It is intuitively clear that 2D trajectories provide projection data that is more complete in terms of Radon space filling, when compared with conventional tomosynthesis using a linearly scanned source. Incorporating this additional information for obtaining improved image quality is, however, not a straightforward problem. The typical tomosynthesis reconstruction algorithms are based on direct inversion methods e.g. Filtered Backprojection (FBP) or iterative algorithms that are variants of the Algebraic Reconstruction Technique (ART). The FBP approach is fast and provides high frequency details in the image but at the same time introduces streaking artifacts degrading the image quality. The iterative methods can reduce the image artifacts by using image priors but suffer from a slow convergence rate, thereby producing images lacking high frequency details. In this paper we propose using a fast converging optimal gradient iterative scheme that has advantages of both the FBP and iterative methods in that it produces images with high frequency details while reducing the image artifacts. We show that using favorable 2D scanning trajectories along with the proposed reconstruction method has the advantage of providing improved depth information for structures such as the spine and potentially producing images with more isotropic resolution.

Khare, Kedar; Claus, Bernhard E. H.; Eberhard, Jeffrey W.



2D electron cyclotron emission imaging at ASDEX Upgrade (invited)  

SciTech Connect

The newly installed electron cyclotron emission imaging diagnostic on ASDEX Upgrade provides measurements of the 2D electron temperature dynamics with high spatial and temporal resolution. An overview of the technical and experimental properties of the system is presented. These properties are illustrated by the measurements of the edge localized mode and the reversed shear Alfven eigenmode, showing both the advantage of having a two-dimensional (2D) measurement, as well as some of the limitations of electron cyclotron emission measurements. Furthermore, the application of singular value decomposition as a powerful tool for analyzing and filtering 2D data is presented.

Classen, I. G. J. [Max Planck Institut fuer Plasmaphysik, 85748 Garching (Germany); FOM-Institute for Plasma Physics, Rijnhuizen, 3430 BE Nieuwegein (Netherlands); Boom, J. E.; Vries, P. C. de [FOM-Institute for Plasma Physics, Rijnhuizen, 3430 BE Nieuwegein (Netherlands); Suttrop, W.; Schmid, E.; Garcia-Munoz, M.; Schneider, P. A. [Max Planck Institut fuer Plasmaphysik, 85748 Garching (Germany); Tobias, B.; Domier, C. W.; Luhmann, N. C. Jr. [University of California at Davis, Davis, California 95616 (United States); Donne, A. J. H. [FOM-Institute for Plasma Physics, Rijnhuizen, 3430 BE Nieuwegein (Netherlands); Eindhoven University of Technology, 5600 MB Eindhoven (Netherlands); Jaspers, R. J. E. [Eindhoven University of Technology, 5600 MB Eindhoven (Netherlands); Park, H. K. [POSTECH, Pohang, Gyeongbuk, 790-784 (Korea, Republic of); Munsat, T. [University of Colorado, Boulder, Colorado 80309 (United States)



2-D phase contrast imaging of turbulence structure on LHD  

Microsoft Academic Search

CO2 laser-based phase contrast imaging (PCI) equipped with a 6 by 8 element two-dimensional (2-D) array of photoconductors is used on the large helical device (LHD) for studying plasma density microfluctuations. Observing 2-D structures of turbulence and strong magnetic shear along the viewing line on LHD permit conversion of a 2-D-PCI image to a 2-D picture of the radial distribution

Leonid N. Vyacheslavov; K. Tanaka; A. L. Sanin; K. Kawahata; C. Michael; T. Akiyama



2-D Temperature Mapping in Fluorocarbon Plasmas  

SciTech Connect

Two-dimensional maps of rotational temperature in CF4 plasmas were determined using planar laser-induced fluorescence measurements of CF A2{sigma}+ - X2{pi} (1,0). Rotational temperatures are expected to be in equilibrium with gas temperatures under the present conditions. Experiments were performed in a capacitively-coupled, parallel-plate reactor at pressures from 27 Pa to 107 Pa and powers of 10 W to 30 W. The effects of electrode cooling and having a wafer present were also examined. Measured temperatures ranged between 273 K{+-}15 K and 480 K{+-}15 K. The strong temperature gradients found in these plasmas can have serious effects on density measurements that probe a single rotational level, as well as on reaction rate constants and interpretation of density gradients.

Steffens, Kristen L.; Sobolewski, Mark A. [Process Measurements Division, National Institute of Standards and Technology, Gaithersburg, MD 20899 (United States)



Evaluation of Stereoscopic Images: Beyond 2D Quality  

Microsoft Academic Search

Perceived image quality is a standard evaluation concept for 2D imaging systems. When applied to stereoscopic 3D imaging systems, however, it does not incorporate the added value of stereoscopic depth. Higher level evaluation concepts (natural- ness and viewing experience) are proposed that are sensitive to both image quality and stereoscopic depth. A 3D Quality Model is constructed in which such

Marc Lambooij; Wijnand IJsselsteijn; Don G. Bouwhuis; Ingrid Heynderickx



2D Images into 3D Models  

Microsoft Academic Search

There are many applications, such as rapid prototyping, simulations and presentations, where non-professional computer end-users could benefit from the ability to create simple 3D models. Existing tools are geared towards the creation of production quality 3D models by professional users with sufficient background, time and motivation to overcome steep learning curves. Inflatable Icons combine diffusion-based image extrusion with a number

Alexander Repenning


3D Modeling From 2D Images  

Microsoft Academic Search

This article will give an overview of the methods of transition from the set of images into 3D model. Direct method of creating 3D model using 3D software will be described. Creating photorealistic 3D models from a set of photographs is challenging problem in computer vision because the technology is still in its development stage while the demands for 3D

Lana Madracevic; Stjepan Sogoric



Optical imaging systems analyzed with a 2D template.  


Present determination of optical imaging systems specifications are based on performance values and modulation transfer function results carried with a 1D resolution template (such as the USAF resolution target or spoke templates). Such a template allows determining image quality, resolution limit, and contrast. Nevertheless, the conventional 1D template does not provide satisfactory results, since most optical imaging systems handle 2D objects for which imaging system response may be different by virtue of some not readily observable spatial frequencies. In this paper we derive and analyze contrast transfer function results obtained with 1D as well as 2D templates. PMID:22614498

Haim, Harel; Konforti, Naim; Marom, Emanuel



Lossless image compression using 2D allpass filters  

Microsoft Academic Search

In this paper, a reversible integer-to-integer wavelet transform based on non-separable 2D allpass filters is proposed for lossless image coding. The number of rounding operations included in the reversible wavelet transform is reduced by using non-separable 2D allpass filters, thus it is expected to get better coding performance. The lossless coding performance of the proposed reversible wavelet transform is evaluated

Xi Zhang; Kosuke Ohno



3D temperature field reconstruction based on the interpolation of 2D acoustic reconstructions  

NASA Astrophysics Data System (ADS)

The reconstructions of 3D temperature fields by acoustic tomography are simulated studied. Four planes along the axial of the space to be measured are selected as typical planes. Eight acoustic sensors are amounted on each plane's periphery. Using the reconstruction algorithm based on radial basis function approximation and Tikhonov regularization we proposed, the 2D temperature fields in the four planes are reconstructed, then the 3D temperature field is reconstructed by interpolation of the 2D images. Reconstructions of three temperature field models by using exact and corrupted time-of-flight data demonstrate that the method proposed in this paper has good ability in complex 3D temperature field reconstruction.

Yan, Hua; Dou, Hui; Chen, Guannan; Yao, Li



Evidence of excited state localization and static disorder in LH2 investigated by 2D-polarization single-molecule imaging at room temperature.  


Two-dimensional polarization fluorescence imaging of single light harvesting complexes 2 (LH2) of Rps. acidophila was carried out to investigate the polarization properties of excitation and fluorescence emission simultaneously, at room temperature. In two separate experiments we excited LH2 with a spectrally narrow laser line matched to the absorption bands of the two chromophore rings, B800 and B850, thereby indirectly and directly triggering fluorescence of the B850 exciton state. A correlation analysis of the polarization modulation depths in excitation and emission for a large number of single complexes was performed. Our results show, in comparison to B800, that the B850 ring is a more isotropic absorber due to the excitonic nature of its excited states. At the same time, we observed a strong tendency for LH2 to emit with dipolar character, from which preferential localization of the emissive exciton, stable for minutes, is inferred. We argue that the observed effects can consistently be explained by static energetic disorder and/or deformation of the complex, with possible involvement of exciton self-trapping. PMID:24145962

Tubasum, Sumera; Camacho, Rafael; Meyer, Matthias; Yadav, Dheerendra; Cogdell, Richard J; Pullerits, Tõnu; Scheblykin, Ivan G



Improvement of LIEF by wavelength-resolved acquisition of multiple images using a single CCD detector - Simultaneous 2D measurement of air/fuel ratio, temperature distribution of the liquid phase and qualitative distribution of the liquid phase with the Multi-2D technique  

NASA Astrophysics Data System (ADS)

The exciplex tracer system fluorobenzene (FB) and diethyl-methyl-amine (DEMA) in a solution of n-hexane and methyl-tert.-butylether (MTBE) was used to investigate the mixture formation in a fired direct injection spark ignition engine. The scope of this paper is the recently developed Multi-2D technique, which allows for the simultaneous measurement of the local air/fuel ratio (?-distribution of the vapor phase), the qualitative distribution of the liquid phase, the temperature distribution of the liquid phase, and the detection of Mie scattering in this application. Basically, the Multi-2D technique consists of a new optical setup, which images the same field of view four times onto one camera, thus combining spatial and spectral resolution based on interference filters. The liquid temperature is derived via “two-line” thermometry. Using the liquid phase temperature the crosstalk from the liquid into the spectral detection range of the vapor phase is corrected. Quantitative results of the crosstalk-corrected vapor phase signals are achieved by an in-situ calibration.

Wieske, P.; Wissel, S.; Grünefeld, G.; Pischinger, S.



Interactive 2D to 3D stereoscopic image synthesis  

NASA Astrophysics Data System (ADS)

Advances in stereoscopic display technologies, graphic card devices, and digital imaging algorithms have opened up new possibilities in synthesizing stereoscopic images. The power of today"s DirectX/OpenGL optimized graphics cards together with adapting new and creative imaging tools found in software products such as Adobe Photoshop, provide a powerful environment for converting planar drawings and photographs into stereoscopic images. The basis for such a creative process is the focus of this paper. This article presents a novel technique, which uses advanced imaging features and custom Windows-based software that utilizes the Direct X 9 API to provide the user with an interactive stereo image synthesizer. By creating an accurate and interactive world scene with moveable and flexible depth map altered textured surfaces, perspective stereoscopic cameras with both visible frustums and zero parallax planes, a user can precisely model a virtual three-dimensional representation of a real-world scene. Current versions of Adobe Photoshop provide a creative user with a rich assortment of tools needed to highlight elements of a 2D image, simulate hidden areas, and creatively shape them for a 3D scene representation. The technique described has been implemented as a Photoshop plug-in and thus allows for a seamless transition of these 2D image elements into 3D surfaces, which are subsequently rendered to create stereoscopic views.

Feldman, Mark H.; Lipton, Lenny



2D luminescence imaging of pH in vivo.  


Luminescence imaging of biological parameters is an emerging field in biomedical sciences. Tools to study 2D pH distribution are needed to gain new insights into complex disease processes, such as wound healing and tumor metabolism. In recent years, luminescence-based methods for pH measurement have been developed. However, for in vivo applications, especially for studies on humans, biocompatibility and reliability under varying conditions have to be ensured. Here, we present a referenced luminescent sensor for 2D high-resolution imaging of pH in vivo. The ratiometric sensing scheme is based on time-domain luminescence imaging of FITC and ruthenium(II)tris-(4,7-diphenyl-1,10-phenanthroline). To create a biocompatible 2D sensor, these dyes were bound to or incorporated into microparticles (aminocellulose and polyacrylonitrile), and particles were immobilized in polyurethane hydrogel on transparent foils. We show sensor precision and validity by conducting in vitro and in vivo experiments, and we show the versatility in imaging pH during physiological and chronic cutaneous wound healing in humans. Implementation of this technique may open vistas in wound healing, tumor biology, and other biomedical fields. PMID:21262842

Schreml, Stephan; Meier, Robert J; Wolfbeis, Otto S; Landthaler, Michael; Szeimies, Rolf-Markus; Babilas, Philipp



Volumetric elasticity imaging with a 2-D CMUT array.  


This article reports the use of a two-dimensional (2-D) capacitive micro-machined ultrasound transducer (CMUT) to acquire radio-frequency (RF) echo data from relatively large volumes of a simple ultrasound phantom to compare three-dimensional (3-D) elasticity imaging methods. Typical 2-D motion tracking for elasticity image formation was compared with three different methods of 3-D motion tracking, with sum-squared difference (SSD) used as the similarity measure. Differences among the algorithms were the degree to which they tracked elevational motion: not at all (2-D search), planar search, combination of multiple planes and plane independent guided search. The cross-correlation between the predeformation and motion-compensated postdeformation RF echo fields was used to quantify motion tracking accuracy. The lesion contrast-to-noise ratio was used to quantify image quality. Tracking accuracy and strain image quality generally improved with increased tracking sophistication. When used as input for a 3-D modulus reconstruction, high quality 3-D displacement estimates yielded accurate and low noise modulus reconstruction. PMID:20510188

Fisher, Ted G; Hall, Timothy J; Panda, Satchi; Richards, Michael S; Barbone, Paul E; Jiang, Jingfeng; Resnick, Jeff; Barnes, Steve



Region-based Statistical Analysis of 2D PAGE Images  

PubMed Central

A new comprehensive procedure for statistical analysis of two-dimensional polyacrylamide gel electrophoresis (2D PAGE) images is proposed, including protein region quantification, normalization and statistical analysis. Protein regions are defined by the master watershed map that is obtained from the mean gel. By working with these protein regions, the approach bypasses the current bottleneck in the analysis of 2D PAGE images: it does not require spot matching. Background correction is implemented in each protein region by local segmentation. Two-dimensional locally weighted smoothing (LOESS) is proposed to remove any systematic bias after quantification of protein regions. Proteins are separated into mutually independent sets based on detected correlations, and a multivariate analysis is used on each set to detect the group effect. A strategy for multiple hypothesis testing based on this multivariate approach combined with the usual Benjamini-Hochberg FDR procedure is formulated and applied to the differential analysis of 2D PAGE images. Each step in the analytical protocol is shown by using an actual dataset. The effectiveness of the proposed methodology is shown using simulated gels in comparison with the commercial software packages PDQuest and Dymension. We also introduce a new procedure for simulating gel images.

Li, Feng; Seillier-Moiseiwitsch, Francoise; Korostyshevskiy, Valeriy R.



2D/3D image (facial) comparison using camera matching.  


A problem in forensic facial comparison of images of perpetrators and suspects is that distances between fixed anatomical points in the face, which form a good starting point for objective, anthropometric comparison, vary strongly according to the position and orientation of the camera. In case of a cooperating suspect, a 3D image may be taken using e.g. a laser scanning device. By projecting the 3D image onto a 2D image with the suspect's head in the same pose as that of the perpetrator, using the same focal length and pixel aspect ratio, numerical comparison of (ratios of) distances between fixed points becomes feasible. An experiment was performed in which, starting from two 3D scans and one 2D image of two colleagues, male and female, and using seven fixed anatomical locations in the face, comparisons were made for the matching and non-matching case. Using this method, the non-matching pair cannot be distinguished from the matching pair of faces. Facial expression and resolution of images were all more or less optimal, and the results of the study are not encouraging for the use of anthropometric arguments in the identification process. More research needs to be done though on larger sets of facial comparisons. PMID:16337353

Goos, Mirelle I M; Alberink, Ivo B; Ruifrok, Arnout C C



Automatic segmentation of scaling in 2-D psoriasis skin images.  


Psoriasis is a chronic inflammatory skin disease that affects over 3% of the population. Various methods are currently used to evaluate psoriasis severity and to monitor therapeutic response. The PASI system of scoring is widely used for evaluating psoriasis severity. It employs a visual analogue scale to score the thickness, redness (erythema), and scaling of psoriasis lesions. However, PASI scores are subjective and suffer from poor inter- and intra-observer concordance. As an integral part of developing a reliable evaluation method for psoriasis, an algorithm is presented for segmenting scaling in 2-D digital images. The algorithm is believed to be the first to localize scaling directly in 2-D digital images. The scaling segmentation problem is treated as a classification and parameter estimation problem. A Markov random field (MRF) is used to smooth a pixel-wise classification from a support vector machine (SVM) that utilizes a feature space derived from image color and scaling texture. The training sets for the SVM are collected directly from the image being analyzed giving the algorithm more resilience to variations in lighting and skin type. The algorithm is shown to give reliable segmentation results when evaluated with images with different lighting conditions, skin types, and psoriasis types. PMID:23288330

Lu, Juan; Kazmierczak, Ed; Manton, Jonathan H; Sinclair, Rodney



Pulsed laser imaging in practical combustion systems from 2D to 4D  

NASA Astrophysics Data System (ADS)

Laser imaging technologies are now being used in practical combustors, from fuel vapour concentration measurements to liquid drop sizing. Simple 2D imagine has demonstrated its capabilities but has limitations in proving all the required data. Multi-dimension and multi-scalar imaging are demonstrating their power in providing additional information. This paper presents the progression of imaging from 2D to 4D and the advantages gained from the labour intensive multi-imaging processes. Temperature and fuel distribution are of critical interest in most practical combustors. Techniques ranging from simple Planar Laser Induced Fluorescence (PLIF) to more complex multi-scalar techniques such as Laser Sheet Drop-sizing (LSD) and mixture fraction imaging are presented with their potential diagnostic power. Although 2D imaging can provide a great deal of data for axi-symmetric flows, most combustors require characterisation with multiple 2D layers to assemble a fu ll 3D picture of the processes involved. Data is presented for a turbine combustor, showing the development of fuel mixing in the premix duct. The advantages of the complex 4D imaging are shown by the success of fuel imaging in an internal combustion engine where crank-angle resolved images enable the fuel distribution in the combustion cycle and cycle to cycle fluctuations to be quantified.

Kelman, James B.; Sherwood, Glen; O'Young, Frank; Berckmueller, Martin; Jermy, Mark C.; Masri, Assaad R.; Greenhalgh, Douglas A.



Iterative 2D deconvolution of portal imaging radiographs.  


Portal imaging has become an integral part of modern radiotherapy techniques such as IMRT and IGRT. It serves to verify the accuracy of day-to-day patient positioning, a prerequisite for treatment success. However, image blurring attributable to different physical and geometrical effects, analysed in this work, impairs the image quality of the portal images, and anatomical structures cannot always be clearly outlined. A 2D iterative deconvolution method was developed to reduce this image blurring. The affiliated data basis was generated by the separate measurement of the components contributing to image blurring. Secondary electron transport and pixel size within the EPID, as well as geometrical penumbra due to the finite photon source size were found to be the major contributors, whereas photon scattering in the patient is less important. The underlying line-spread kernels of these components were shown to be Lorentz functions. This implies that each of these convolution kernels and also their combination can be characterized by a single characteristic, the width parameter ? of the Lorentz function. The overall resulting ? values were 0.5mm for 6 MV and 0.65 mm for 15 MV. Portal images were deconvolved using the point-spread function derived from the Lorentz function together with the experimentally determined ? values. The improvement of the portal images was quantified in terms of the modulation transfer function of a bar pattern. The resulting clinical images show a clear enhancement of sharpness and contrast. PMID:20888203

Looe, Hui Khee; Harder, Dietrich; Willborn, Kay C; Poppe, Björn



3D Stereo Imaging Technology From 2D Image Sequence  

Microsoft Academic Search

In this paper, we will analyze the depth factor in general monocular video sequence. We can distinguish foreground from background without additional information and then create the binocular image by shifting foreground pixels. By applying CID method, we will get the strength of the sharpness and contrast from image by evaluating the farness of the region based on property of

Fang-Hsuan Cheng; Chien-Chih Chen



Image Appraisal for 2D and 3D Electromagnetic Inversion  

SciTech Connect

Linearized methods are presented for appraising image resolution and parameter accuracy in images generated with two and three dimensional non-linear electromagnetic inversion schemes. When direct matrix inversion is employed, the model resolution and posterior model covariance matrices can be directly calculated. A method to examine how the horizontal and vertical resolution varies spatially within the electromagnetic property image is developed by examining the columns of the model resolution matrix. Plotting the square root of the diagonal of the model covariance matrix yields an estimate of how errors in the inversion process such as data noise and incorrect a priori assumptions about the imaged model map into parameter error. This type of image is shown to be useful in analyzing spatial variations in the image sensitivity to the data. A method is analyzed for statistically estimating the model covariance matrix when the conjugate gradient method is employed rather than a direct inversion technique (for example in 3D inversion). A method for calculating individual columns of the model resolution matrix using the conjugate gradient method is also developed. Examples of the image analysis techniques are provided on 2D and 3D synthetic cross well EM data sets, as well as a field data set collected at the Lost Hills Oil Field in Central California.

Alumbaugh, D.L.; Newman, G.A.



A Nonrigid Kernel-Based Framework for 2D-3D Pose Estimation and 2D Image Segmentation  

Microsoft Academic Search

In this work, we present a nonrigid approach to jointly solving the tasks of 2D-3D pose estimation and 2D image segmentation. In general, most frameworks that couple both pose estimation and segmentation assume that one has exact knowledge of the 3D object. However, under nonideal conditions, this assumption may be violated if only a general class to which a given

Romeil Sandhu; Samuel Dambreville; Anthony J. Yezzi; Allen Tannenbaum



Real-time 2D Imaging of Thermal and Mechanical Tissue Response to Focused Ultrasound  

NASA Astrophysics Data System (ADS)

An integrated system capable of performing high frame-rate two-dimensional (2D) temperature imaging in realtime is has been developed. The system consists of a SonixRP ultrasound scanner and a custom built data processing unit connected with Gigabit Ethernet (GbE). The SonixRP scanner which serves as the frontend of the integrated system allows us to have flexibilities of controlling the beam sequence and accessing the radio frequency (RF) data in realtime through its research interface. The RF data is then streamlined to the backend of the system through GbE, where the data is processed using a 2D temperature estimation algorithm running in a general purpose graphics processing unit (GPU). Using this system, we have developed a 2D high frame-rate imaging mode, M2D, for imaging the mechanical and thermal tissue response to subtherapeutic HIFU beams. In this paper, we present results from imaging subtherapetic HIFU beams in vitro porcine heart before and after lesion formation. The results demonstrate the feasibility of tissue parameter changes due to HIFU-induced lesions.

Liu, Dalong; Ebbini, Emad S.



Semiconductor detectors for 2D X-ray imaging  

NASA Astrophysics Data System (ADS)

Semiconductor nuclear radiation detectors are nowadays of current use for high-resolution spectrometry in a number of fields, including those involving X-ray measurements. The significant advances achieved during the last 10 years in materials properties, detector characteristics, and high-quality electronic systems, now make it possible to go one step further and to build 2D X-ray imaging systems based on semiconductor detectors. It is the aim of this paper to present the state-of-the-art of X-ray imaging systems based on such devices. First the basic principles involved will be presented. The main requirements (detector size, spatial resolution, pixel number, dynamics, counting rate, etc.) and limitations (physical and experimental limitations), with respect to the applications envisaged (material science, medical or industrial imaging) will be discussed. The major properties of the semiconductors of interest for such applications will be briefly summarized. Then the working principles and main characteristics of existing systems based on various semiconductor materials and devices will be reviewed and compared to those of conventional X-ray imagers. Finally, possible evolutions will be discussed in terms of new detector materials and new semiconductor devices, taking into account the increasing potential of microelectronics technology.

Ponpon, J. P.



Improved T2* Imaging without Increase in Scan Time: SWI Processing of 2D Gradient Echo.  


BACKGROUND AND PURPOSE:2D gradient-echo imaging is sensitive to T2* lesions (hemorrhages, mineralization, and vascular lesions), and susceptibility-weighted imaging is even more sensitive, but at the cost of additional scan time (SWI: 5-10 minutes; 2D gradient-echo: 2 minutes). The long acquisition time of SWI may pose challenges in motion-prone patients. We hypothesized that 2D SWI/phase unwrapped images processed from 2D gradient-echo imaging could improve T2* lesion detection.MATERIALS AND METHODS:2D gradient-echo brain images of 50 consecutive pediatric patients (mean age, 8 years) acquired at 3T were retrospectively processed to generate 2D SWI/phase unwrapped images. The 2D gradient-echo and 2D SWI/phase unwrapped images were compared for various imaging parameters and were scored in a blinded fashion.RESULTS:Of 50 patients, 2D gradient-echo imaging detected T2* lesions in 29 patients and had normal findings in 21 patients. 2D SWI was more sensitive than standard 2D gradient-echo imaging in detecting T2* lesions (P < .0001). 2D SWI/phase unwrapped imaging also improved delineation of normal venous structures and nonpathologic calcifications and helped distinguish calcifications from hemorrhage. A few pitfalls of 2D SWI/phase unwrapped imaging were noted, including worsened motion and dental artifacts and challenges in detecting T2* lesions adjacent to calvaria or robust deoxygenated veins.CONCLUSIONS:2D SWI and associated phase unwrapped images processed from standard 2D gradient-echo images were more sensitive in detecting T2* lesions and delineating normal venous structures and nonpathologic mineralization, and they also helped distinguish calcification at no additional scan time. SWI processing of 2D gradient-echo images may be a useful adjunct in cases in which longer scan times of 3D SWI are difficult to implement. PMID:23744690

Soman, S; Holdsworth, S J; Barnes, P D; Rosenberg, J; Andre, J B; Bammer, R; Yeom, K W



2D luminescence imaging of physiological wound oxygenation.  


In cutaneous wound healing, the role of oxygen in vivo is poorly understood. We studied wound surface pO(2) during physiological wound healing in humans. Split-thickness skin graft donor sites (n=12) served as standardized wound models. Wound surface pO(2) was measured at 1, 6 and 14days after split-skin harvesting using two-dimensional luminescence lifetime imaging (2D-LLI) of palladium(II)-meso-tetraphenyl-tetrabenzoporphyrin (Pd-TPTBP) in polystyrene-co-acrylonitrile (PSAN) particles on transparent foils. In another experiment, we removed the stratum corneum (SC) on the volar forearm (n=10) by tape strippings to study the impact of the SC on the epidermal oxygen barrier. Split-skin donor site pO(2) significantly decreased during the time course of physiological healing. Regional differences in pO(2) within donor site wounds were visualized for the first time in literature. No difference was found in pO(2) before and after SC removal, showing that the SC is not a major constituent of the epidermal oxygen barrier. PMID:21443617

Schreml, Stephan; Meier, Robert J; Wolfbeis, Otto S; Maisch, Tim; Szeimies, Rolf-Markus; Landthaler, Michael; Regensburger, Johannes; Santarelli, Francesco; Klimant, Ingo; Babilas, Philipp



Calibration of an acoustic system for measuring 2-D temperature distribution around hydrothermal vents.  


One of the fundamental purposes of quantitative acoustic surveys of seafloor hydrothermal vents is to measure their 2-D temperature distributions. Knowing the system latencies and the acoustic center-to-center distances between the underwater transducers in an acoustic tomography system is fundamental to the overall accuracy of the temperature reconstruction. However, commercial transducer sources typically do not supply the needed data. Here we present a novel calibration algorithm to automatically determine the system latencies and the acoustic center-to-center distances. The possible system latency error and the resulting temperature error are derived and analyzed. We have also developed the experimental setup for calibration. To validate the effectiveness of the proposed calibration method, an experimental study was performed on acoustic imaging of underwater temperature fields in Lake Qiezishan, located at Longling County, Yunnan Province, China. Using the calibrated data, the reconstructed temperature distributions closely resemble the actual distributions measured with thermocouples, thus confirming the effectiveness of our algorithm. PMID:23375572

Fan, Wei; Chen, Chen-Tung Arthur; Chen, Ying



An efficient VLSI architecture for 2-D wavelet image coding with novel image scan  

Microsoft Academic Search

A folded very large scale integration (VLSI) architecture is presented for the implementation of the two-dimensional discrete wavelet transform, without constraints on the choice of the wavelet-filter bank. The proposed architecture is dedicated to flexible block-oriented image processing, such as adaptive vector quantization used in wavelet image coding. We show that reading the image along a two-dimensional (2-D) pseudo-fractal scan

Gauthier Lafruit; Francky Catthoor; Jan P. H. Cornelis; Hugo J. De Man



Neuro-Fuzzy Based Clustering Approach For Content Based Image Retrieval Using 2D- Wavelet Transform  

Microsoft Academic Search

Abstract—In this paper we introduce neuro-fuzzy based clustering approach for content based image retrieval using 2D-wavelet transform(2D-DWT). Most of the ,image retrieval systems are still incapable of providing retrieval result with high retrieval accuracy and less computational complexity.To address this problem, we developed neural network -fuzzy logic cluster based approach for content based image retrieval using 2D-wavelet transform. The system

V. Balamurugan; P. Anandhakumar



A 2-D imaging heat-flux gauge  

SciTech Connect

This report describes a new leadless two-dimensional imaging optical heat-flux gauge. The gauge is made by depositing arrays of thermorgraphic-phosphor (TP) spots onto the faces of a polymethylpentene is insulator. In the first section of the report, we describe several gauge configurations and their prototype realizations. A satisfactory configuration is an array of right triangles on each face that overlay to form squares when the gauge is viewed normal to the surface. The next section of the report treats the thermal conductivity of TPs. We set up an experiment using a comparative longitudinal heat-flow apparatus to measure the previously unknown thermal conductivity of these materials. The thermal conductivity of one TP, Y{sub 2}O{sub 3}:Eu, is 0.0137 W/cm{center dot}K over the temperature range from about 300 to 360 K. The theories underlying the time response of TP gauges and the imaging characteristics are discussed in the next section. Then we discuss several laboratory experiments to (1) demonstrate that the TP heat-flux gauge can be used in imaging applications; (2) obtain a quantum yield that enumerates what typical optical output signal amplitudes can be obtained from TP heat-flux gauges; and (3) determine whether LANL-designed intensified video cameras have sufficient sensitivity to acquire images from the heat-flux gauges. We obtained positive results from all the measurements. Throughout the text, we note limitations, areas where improvements are needed, and where further research is necessary. 12 refs., 25 figs., 4 tabs.

Noel, B.W.; Borella, H.M. (Los Alamos National Lab., NM (United States)); Beshears, D.L.; Sartory, W.K.; Tobin, K.W.; Williams, R.K. (Oak Ridge National Lab., TN (United States)); Turley, W.D. (EG and G Energy Measurements, Inc., Goleta, CA (United States). Santa Barbara Operations)



2-D Temperature Measurements of the Divertor Using the Line-to-continuum Ratio Method  

NASA Astrophysics Data System (ADS)

Alcator C-Mod currently employs a tangentially viewing divertor TV system consisting of two CCD cameras with nearly identical views. The cameras are filtered, typically for D_? and CII lines (? 515 nm). The recorded images are inverted assuming toroidal symmetry, yielding 2-D emissivity profiles. Due to the low level of carbon after boronization the emission detected by the camera filtered for the CII lines is dominated by continuum radiation. With the 2-D profiles of D_? and continuum emission, effective temperature measurements are obtained using the line-to-continuum ratio method,(Hans R. Griem, \\underlinePrinciples of Plasma Spectroscopy), (Cambridge University Press, New York, 1997), p. 291. which assumes that the continuum is due to ion-electron bremsstrahlung and radiative recombination only. However, additional continuum radiation has been observed previously in the divertor region.(J. L. Terry et al.), in \\underlineProc. of the 26th Euro. Phys. Soc. Conf. on \\underlineContr. Fus. and Plasma Phys., edited by B. Schweer, G. Van Oost, and E. Vietzke (Institute of Physics, London, UK 1999), pp. 325-328. 2-D plots of D_?, continuum, and effective temperature will be presented.

Boswell, C. J.; Terry, J. L.; Lipschultz, B.



A Nonrigid Kernel-Based Framework for 2D-3D Pose Estimation and 2D Image Segmentation  

PubMed Central

In this work, we present a nonrigid approach to jointly solving the tasks of 2D-3D pose estimation and 2D image segmentation. In general, most frameworks that couple both pose estimation and segmentation assume that one has exact knowledge of the 3D object. However, under nonideal conditions, this assumption may be violated if only a general class to which a given shape belongs is given (e.g., cars, boats, or planes). Thus, we propose to solve the 2D-3D pose estimation and 2D image segmentation via nonlinear manifold learning of 3D embedded shapes for a general class of objects or deformations for which one may not be able to associate a skeleton model. Thus, the novelty of our method is threefold: First, we present and derive a gradient flow for the task of nonrigid pose estimation and segmentation. Second, due to the possible nonlinear structures of one’s training set, we evolve the preimage obtained through kernel PCA for the task of shape analysis. Third, we show that the derivation for shape weights is general. This allows us to use various kernels, as well as other statistical learning methodologies, with only minimal changes needing to be made to the overall shape evolution scheme. In contrast with other techniques, we approach the nonrigid problem, which is an infinite-dimensional task, with a finite-dimensional optimization scheme. More importantly, we do not explicitly need to know the interaction between various shapes such as that needed for skeleton models as this is done implicitly through shape learning. We provide experimental results on several challenging pose estimation and segmentation scenarios.

Sandhu, Romeil; Dambreville, Samuel; Yezzi, Anthony; Tannenbaum, Allen



Apparent 3-D image perceived from luminance-modulated two 2-D images displayed at different depths.  


An apparent 3-D image can be perceived from only two 2-D images displayed at different depths, when an observer views them from the direction in which they are overlapped. The two 2-D images are created from an original 2-D image by dividing its luminance according to independently obtained depth information. Subjective test results show that (1) an apparent 3-D image is perceived and (2) the perceived depth continuously varies according to the change in luminance ratio between the two 2-D images. PMID:14967205

Suyama, Shiro; Ohtsuka, Sakuichi; Takada, Hideaki; Uehira, Kazutake; Sakai, Sigenobu



A review of 3D/2D registration methods for image-guided interventions.  


Registration of pre- and intra-interventional data is one of the key technologies for image-guided radiation therapy, radiosurgery, minimally invasive surgery, endoscopy, and interventional radiology. In this paper, we survey those 3D/2D data registration methods that utilize 3D computer tomography or magnetic resonance images as the pre-interventional data and 2D X-ray projection images as the intra-interventional data. The 3D/2D registration methods are reviewed with respect to image modality, image dimensionality, registration basis, geometric transformation, user interaction, optimization procedure, subject, and object of registration. PMID:20452269

Markelj, P; Tomaževi?, D; Likar, B; Pernuš, F



Radiology Lab 0: Introduction to 2D and 3D Imaging  

NSDL National Science Digital Library

This is a self-directed learning module to introduce students to basic concepts of imaging technology as well as to give students practice going between 2D and 3D imaging using everyday objects.Annotated: true

Shaffer, Kitt



Integration of Local Image Cues for Probabilistic 2D Pose Recovery  

Microsoft Academic Search

A novel probabilistic formulation for 2-D human pose recovery from monocular images is proposed. It relies on a bottom-up approach based on an iterative process between clustering and body model fitting. Body parts are segmented from the foreground by clustering a set of images cues. Clustering is driven by 2D human body model fitting to obtain optimal segmentation while the

Paul Kuo; Dimitrios Makris; Najla Megherbi; Jean-christophe Nebel



Comparison of 2D and 3D time-reverse imaging—A numerical case study  

NASA Astrophysics Data System (ADS)

Time-reverse imaging has become an efficient tool to detect the origin of passively acquired seismic tremor signals. Practical experience has mainly been developed for 2D applications. Three component signals are reduced to two components and reverse propagated on the plane vertically below a station line. The data used for time-reverse imaging are the vertical and the horizontal particle displacement parallel to the line. Dropping the horizontal component perpendicular to the line causes partial loss of information on particle motion and directivity of the recorded waves. We present a comparison of 2D and 3D time-reverse imaging for a specific site with small cross-line gradients and investigate how closely 2D imaging approximates 3D imaging. Our large-scale synthetic survey with different S/N-ratios demonstrates how a subsurface source of tremor-like signals is imaged in different vertical planes. An imaging condition based on the energy density gives best results. We observe higher sensitivity to noise and stronger out-of-plane focusing for 2D than for 3D imaging. We suggest normalized visualization of multiple planes from 2D imaging in one 3D display as an approach to reliably locate sources. Comparison with examples of full 3D time-reverse imaging shows that normalized visualization of multiple 2D planes with a proper imaging condition can adequately approximate the result from full 3D imaging for the particular model considered in this study.

Steiner, Brian; Saenger, Erik H.



Fast computation of 2-D image moments using biaxial transform  

Microsoft Academic Search

In this paper a new transform is introduced. This transform is based on dividing the image into four quadrants. The transform can be generated by adding or subtracting the gray levels of each two axially symmetric points in the original image. The addition or subtraction is dependent on the quadrant position. The newly transformed quadrants can then be used to

Saeid Belkasim; Mohamed Kamel



3-D Deep Penetration Photoacoustic Imaging with a 2-D CMUT Array.  


In this work, we demonstrate 3-D photoacoustic imaging of optically absorbing targets embedded as deep as 5 cm inside a highly scattering background medium using a 2-D capacitive micromachined ultrasonic transducer (CMUT) array with a center frequency of 5.5 MHz. 3-D volumetric images and 2-D maximum intensity projection images are presented to show the objects imaged at different depths. Due to the close proximity of the CMUT to the integrated frontend circuits, the CMUT array imaging system has a low noise floor. This makes the CMUT a promising technology for deep tissue photoacoustic imaging. PMID:22977296

Ma, Te-Jen; Kothapalli, Sri Rajasekhar; Vaithilingam, Srikant; Oralkan, Omer; Kamaya, Aya; Wygant, Ira O; Zhuang, Xuefeng; Gambhir, Sanjiv S; Jeffrey, R Brooke; Khuri-Yakub, Butrus T



3-D Deep Penetration Photoacoustic Imaging with a 2-D CMUT Array  

PubMed Central

In this work, we demonstrate 3-D photoacoustic imaging of optically absorbing targets embedded as deep as 5 cm inside a highly scattering background medium using a 2-D capacitive micromachined ultrasonic transducer (CMUT) array with a center frequency of 5.5 MHz. 3-D volumetric images and 2-D maximum intensity projection images are presented to show the objects imaged at different depths. Due to the close proximity of the CMUT to the integrated frontend circuits, the CMUT array imaging system has a low noise floor. This makes the CMUT a promising technology for deep tissue photoacoustic imaging.

Ma, Te-Jen; Kothapalli, Sri Rajasekhar; Vaithilingam, Srikant; Oralkan, Omer; Kamaya, Aya; Wygant, Ira O.; Zhuang, Xuefeng; Gambhir, Sanjiv S.; Jeffrey, R. Brooke; Khuri-Yakub, Butrus T.



High contrast 2D visualization of edge plasma instabilities by ECE imaging  

NASA Astrophysics Data System (ADS)

High contrast high resolution 2D images of edge MHD instabilities have been obtained for the KSTAR H-mode plasmas in 2010 using an electron cyclotron emission (ECE) imaging system. A fast structural evolution of the edge instabilities has been identified where the validity of the observed structures, i.e., the local measurement is ensured by the high contrast. On the other hand, the exact interpretation of the ECE intensity (Trad) is not straightforward due to the marginal optical depth ( ~ 1) in the plasma edge region. The effect of the electron temperature (Te) and density (ne) profiles in the edge region on the ECE localization and intensity have been evaluated for typical KSTAR H-mode discharges.

Yun, G. S.; Choi, M. J.; Lee, W.; Park, H. K.; Domier, C. W.; Luhmann, N. C., Jr.



Facial feature detection and face recognition from 2D and 3D images  

Microsoft Academic Search

This paper presents a feature-based face recognition system based on both 3D range data as well as 2D gray-level facial images. Feature points are described by Gabor filter responses in the 2D domain and Point Signature in the 3D domain. Extracted shape features from 3D feature points and texture features from 2D feature points are first projected into their own

Yingjie Wang; Chin-seng Chua; Yeong-khing Ho



Magnetic susceptibility measurement using 2D magnetic resonance imaging  

NASA Astrophysics Data System (ADS)

The authors describe a nuclear magnetic resonance (NMR) method for measuring the magnetic susceptibility of bar-shaped samples that have an arbitrary cross-section and do not produce an MR signal. The method is based on the measurement of the 2D map of the reaction field in the vicinity of a non-ferromagnetic sample and on the calculation of magnetic susceptibility from a known reaction field. The verification of the technique was realized via modelling the measured configuration in the ANSYS program by means of the finite element method and through an experimental measurement of MR-compatible and MR-incompatible materials carried out on a tomograph. A great advantage of the proposed susceptibility evaluation method consists in the use of only standard commercially used devices without the need of any special sequences. The method is suitable for bar-shaped samples having an arbitrary cross-section; moreover, conditions are given for the selection of the cross-section/length ratio of a sample to be measured.

Marcon, P.; Bartusek, K.; Burdkova, M.; Dokoupil, Z.



2-D Optical Imaging of Permanent Magnet ECR Source  

NASA Astrophysics Data System (ADS)

Optical images of a permanent magnet ECR source were collected with a CCD camera (W. Getty and J. Geddes, J. Vac. Sci. Technol. B 12, pp. 408-415 (Jan/Feb 1994)) The plasma images were focused directly on the CCD. The images indicate field patterns for various pressures, flowrates, and power. A 1-kW, 2.45 GHz microwave source is connected through a circulator and a three-stub tuner to a horn which expands the microwave aperture to a 15 cm x 20 cm rectangle. The horn is attached to the top plate of the vacuum chamber which holds a 15 cm x 20 cm aluminum 6 slot grill containing 5 rows of permanent magnets. The ECR surface of 875 G is approximately 1 cm from the grill. The plasma expands to fill the 28-cm diameter chamber. Depending upon the magnetic configuration and the input conditions, the mode of the plasma changes. This is noted in the two dimensional optical images observed by the CCD. These results will be compared to Langmuir probe data, microwave interferometry, and optical emission spectroscopy. Etch results of oxide patterned silicon wafers will also be discussed. The results of these diagnostics indicate the uniformity of this new plasma source in different modes of operation.

Wilson, Aaron R.; Shannon, Steve S.; Brake, Mary L.; Getty, Ward D.



2-D image segmentation using minimum spanning trees  

SciTech Connect

This paper presents a new algorithm for partitioning a gray-level image into connected homogeneous regions. The novelty of this algorithm lies in the fact that by constructing a minimum spanning tree representation of a gray-level image, it reduces a region partitioning problem to a minimum spanning tree partitioning problem, and hence reduces the computational complexity of the region partitioning problem. The tree-partitioning algorithm, in essence, partitions a minimum spanning tree into subtrees, representing different homogeneous regions, by minimizing the sum of variations of gray levels over all subtrees under the constraints that each subtree should have at least a specified number of nodes, and two adjacent subtrees should have significantly different average gray-levels. Two (faster) heuristic implementations are also given for large-scale region partitioning problems. Test results have shown that the segmentation results are satisfactory and insensitive to noise.

Xu, Y.; Uberbacher, E.C.



A Comparison of Simularity Measures for use in 2D-3D Medical Image Registration  

Microsoft Academic Search

A comparison of six similarity measures for use in intensity-based two-dimensional-three-dimensional (2-D-3-D) image registration is presented. The accuracy of the similarity measures are compared to a \\

Graeme P. Penney; Jürgen Weese; John A. Little; Paul Desmedt; Derek L. G. Hill; David J. Hawkes



A 2-D orientation-adaptive prediction filter in lifting structures for image coding  

Microsoft Academic Search

Lifting-style implementations of particular wavelets are popular in image coders. We present a 2-D extension and modification to the prediction part of the lifting implementation type Daubechies 5\\/3 wavelet. The 2-D prediction filter predicts the value of the next polyphase component according to an edge orientation estimator of the image. Consequently, the prediction domain is allowed to rotate + or

Ömer Nezih Gerek; A. Enis Çetin



Determining 2D notch SIFs by the image-correlation method  

Microsoft Academic Search

This study evaluates the two-dimensional (2D) stress intensity factors (SIFs) of a sharp V-notch using the image-correlation experiment and least-square method for isotropic materials. First, the William's eigenfunction and complex displacement function approach are deduced into a least-square form, and then displacement fields from the image-correlation experiment are substituted into the least-square equation to evaluate the 2D SIFs. Compared with

S. H. Ju; H. Y. Chung; S. H. Liu



Registration of 3-D CT and 2-D Flat Images of Mouse via Affine Transformation  

Microsoft Academic Search

It is difficult to directly coregister the 3-D fluorescence molecular tomography (FMT) image of a small tumor in a mouse whose maximal diameter is only a few millimeters with a larger CT image of the entire animal that spans about 10 cm. This paper proposes a new method to register 2-D flat and 3-D CT image first to facilitate the

Zheng Xia; Xishi Huang; Xiaobo Zhou; Youxian Sun; V. Ntziachristos; Stephen Wong



2D imaging and 3D sensing data acquisition and mutual registration for painting conservation  

Microsoft Academic Search

We describe the application of 2D and 3D data acquisition and mutual registration to the conservation of paintings. RGB color image acquisition, IR and UV fluorescence imaging, together with the more recent hyperspectral imaging (32 bands) are among the most useful techniques in this field. They generally are meant to provide information on the painting materials, on the employed techniques

Raffaella Fontana; Maria Chiara Gambino; Marinella Greco; Luciano Marras; Enrico M. Pampaloni; Anna Pelagotti; Luca Pezzati; Pasquale Poggi



Waveform Tomography Strategies for Imaging 2D Attenuation Structure  

NASA Astrophysics Data System (ADS)

Waveform Tomography, when implemented in the frequency-domain, potentially yields images of the intrinsic attenuation from seismic waveform data (Pratt et al., 1998). The attenuation (or its inverse, the seismic Q value) is strongly related to rheology, fluid flow, pore fluid content and fractures. Since phase and amplitude anomalies are also caused by velocity structure (due to geometrical and scattering effects), it is critical to assess inversion strategies as to their ability to resolve these effects. We compared two sets of strategies: first, velocity and attenuation models were updated jointly at each iteration ("simultaneous inversio"). In a second test, ("sequential inversion"), a velocity model alone was first inverted, followed by simultaneous inversion. While the predicted waveforms from both strategies agreed with the observed data, only the sequential inversion strategy imaged attenuation structure well in the presence of small-scale velocity heterogeneities. This highlights the strong dependence of attenuation imaging on the quality of the velocity model. We then tested the approach using a shallow seismic dataset collected on an engineered clay embankment at Seven Sisters Falls, Manitoba. The test embankment contained three targets composed of granitic rip- rap; these corresponded to higher velocities and higher scattering potential than the surrounding in-situ clays. Waveform Tomography was applied to long-offset refraction data collected over the embankment using 70 weight-drop shots and 48 geophones. The starting model was developed with traveltime tomography on the hand-picked first arrivals. The data were inverted between 20 Hz and 150 Hz, corresponding to wavelengths between approximately 100 m and 13 m. We were able to resolve sub- wavelength targets on the order of 3-4 m in cross-section using the final velocity model. Interpretation of the seismic-Q images along with the velocity allowed us to define the target positions. In order to assess the quality of our model fit, we compared synthetic results with the real data. A very good fit between model and observed data was achieved, indicating the reliability of the results.

Pratt, R. G.; Kamei, R.; Smithyman, B.



Imaging 2-D Structures With Receiver Functions Using Harmonic Stripping  

NASA Astrophysics Data System (ADS)

I present a novel technique to image dipping and anisotropic structures using receiver functions. Receiver functions isolate phase conversions from interfaces close to the seismic station. Standard analysis assumes a quasi-flat layered structure and dampens arrivals from dipping interfaces and anisotropic layers, with attempts to extract information on such structures relying on cumbersome and nonunique forward modeling. I use a simple relationship between the radial and transverse component receiver function to detect dipping and anisotropic layers and map their depth and orientation. For dipping interfaces, layers with horizontal or plunging axis anisotropy, and point scatterers, the following relationships hold: After subtracting the azimuthally invariant portion of the radial receiver functions, the remaining signal is an azimuthally shifted version of the transverse receiver functions. The strike of the dipping interface or anisotropy is given by the azimuth of polarity reversals, and the type of structure can be inferred from the amount of phase shift between the components. For a known structure type, the phase shift between the two components provides pseudoevents from back-azimuths with little seismicity. The technique allows structural mapping at depth akin to geological mapping of rock fabric and dipping layers at the surface. It reduces complex wavefield effects to two simple and geologically meaningful parameters, similar to shear wave splitting. I demonstrate the method on the Wind River Thrust as well as other structures within the Transportable Array footprint.

Schulte-Pelkum, V.



Imaging Excited State Dynamics with 2d Electronic Spectroscopy  

NASA Astrophysics Data System (ADS)

Excited states in the condensed phase have extremely high chemical potentials making them highly reactive and difficult to control. Yet in biology, excited state dynamics operate with exquisite precision driving solar light harvesting in photosynthetic complexes though excitonic transport and photochemistry through non-radiative relaxation to photochemical products. Optimized by evolution, these biological systems display manifestly quantum mechanical behaviors including coherent energy transfer, steering wavepacket trajectories through conical intersections and protection of long-lived quantum coherence. To image the underlying excited state dynamics, we have developed a new spectroscopic method allowing us to capture excitonic structure in real time. Through this method and other ultrafast multidimensional spectroscopies, we have captured coherent dynamics within photosynthetic antenna complexes. The data not only reveal how biological systems operate, but these same spectral signatures can be exploited to create new spectroscopic tools to elucidate the underlying Hamiltonian. New data on the role of the protein in photosynthetic systems indicates that the chromophores mix strongly with some bath modes within the system. The implications of this mixing for excitonic transport will be discussed along with prospects for transferring underlying design principles to synthetic systems.

Engel, Gregory S.



Accurate positioning for head and neck cancer patients using 2D and 3D image guidance  

PubMed Central

Our goal is to determine an optimized image-guided setup by comparing setup errors determined by two-dimensional (2D) and three-dimensional (3D) image guidance for head and neck cancer (HNC) patients immobilized by customized thermoplastic masks. Nine patients received weekly imaging sessions, for a total of 54, throughout treatment. Patients were first set up by matching lasers to surface marks (initial) and then translationally corrected using manual registration of orthogonal kilovoltage (kV) radiographs with DRRs (2D-2D) on bony anatomy. A kV cone beam CT (kVCBCT) was acquired and manually registered to the simulation CT using only translations (3D-3D) on the same bony anatomy to determine further translational corrections. After treatment, a second set of kVCBCT was acquired to assess intrafractional motion. Averaged over all sessions, 2D-2D registration led to translational corrections from initial setup of 3.5 ± 2.2 (range 0–8) mm. The addition of 3D-3D registration resulted in only small incremental adjustment (0.8 ± 1.5 mm). We retrospectively calculated patient setup rotation errors using an automatic rigid-body algorithm with 6 degrees of freedom (DoF) on regions of interest (ROI) of in-field bony anatomy (mainly the C2 vertebral body). Small rotations were determined for most of the imaging sessions; however, occasionally rotations > 3° were observed. The calculated intrafractional motion with automatic registration was < 3.5 mm for eight patients, and < 2° for all patients. We conclude that daily manual 2D-2D registration on radiographs reduces positioning errors for mask-immobilized HNC patients in most cases, and is easily implemented. 3D-3D registration adds little improvement over 2D-2D registration without correcting rotational errors. We also conclude that thermoplastic masks are effective for patient immobilization.

Kang, Hyejoo; Lovelock, Dale M.; Yorke, Ellen D.; Kriminiski, Sergey; Lee, Nancy; Amols, Howard I.



Gradient-based registration of 3D MR and 2D X-ray images  

Microsoft Academic Search

In this paper, we present a novel method for registering a 3D MR image to 2D X-ray images with the final goal to estimate the position and orientation of the patient during surgery or external beam radiotherapy. By using 3D MR preoperative images instead of CT images, we increase a soft tissue contrast and reduce the dose delivered to the

Dejan Tomazevic; Bostjan Likar; Franjo Pernus



2D-1D Wavelet Reconstruction as a Tool for Source Finding in Spectroscopic Imaging Surveys  

NASA Astrophysics Data System (ADS)

Today, image denoising by thresholding of wavelet coefficients is a commonly used tool for 2D image enhancement. Since the data product of spectroscopic imaging surveys has two spatial dimensions and one spectral dimension, the techniques for denoising have to be adapted to this change in dimensionality. In this paper we will review the basic method of denoising data by thresholding wavelet coefficients and implement a 2D-1D wavelet decomposition to obtain an efficient way of denoising spectroscopic data cubes. We conduct different simulations to evaluate the usefulness of the algorithm as part of a source finding pipeline.

Flöer, L.; Winkel, B.



Tracking Nonrigid Motion and Structure from 2D Satellite Cloud Images without Correspondences  

Microsoft Academic Search

Tracking both structure and motion of nonrigid objects from monocular images is an important problem in vision. In this paper, a hierarchical method which integrates local analysis (that recovers small details) and global analysis (that appropriately limits possible nonrigid behaviors) is developed to recover dense depth values and nonrigid motion from a sequence of 2D satellite cloud images without any

Lin Zhou; Chandra Kambhamettu; Dmitry B. Goldgof; Kannappan Palaniappan; Frederick Hasler



A New Approach to Tracking 3D Objects in 2D Image Sequences  

Microsoft Academic Search

We present a new technique for tracking 3D objectsfrom 2D image sequences through the integrationof qualitative and quantitative techniques.The deformable models are initializedbased on a previously developed part-based qualitativeshape segmentation system. Using aphysics-based quantitative approach, objects aresubsequently tracked without feature correspondencebased on generalized forces computed fromthe stereo images. The automatic prediction ofpossible edge occlusion and...

Michael Chan; Dimitris N. Metaxas; Sven J. Dickinson



GPU Acceleration of 2D-DWT Image Compression in MATLAB with CUDA  

Microsoft Academic Search

This article presents the details about the acceleration of 2D wavelet-based medical data (image) compression on MATLAB with CUDA. It is obvious that the diagnostic materials (mostly as acertain type of image) are increasingly acquired in a digital format. Therefore, common need to daily manipulate huge amount of data brought about the issue of compression within a very less stipulated

Vaclav Simek; Ram Rakesh Asn



2D-CELL: image processing software for extraction and analysis of 2-dimensional cellular structures  

Microsoft Academic Search

2D-CELL is a software package for the processing and analyzing of photographic images of cellular structures in a largely interactive way. Starting from a binary digitized image, the programs extract the line network (skeleton) of the structure and determine the graph representation that best models it. Provision is made for manually correcting defects such as incorrect node positions or dangling

F. Righetti; H. Telley; Th. M. Leibling; A. Mocellin



Robust Gradient-Based 3-D\\/2-D Registration of CT and MR to X-Ray Images  

Microsoft Academic Search

One of the most important technical challenges in image-guided intervention is to obtain a precise transformation between the intrainterventional patient's anatomy and corresponding preinterventional 3-D image on which the intervention was planned. This goal can be achieved by acquiring intrainterventional 2-D images and matching them to the preinterventional 3-D image via 3-D\\/2-D image registration. A novel 3-D\\/2-D registration method is

Primoz Markelj; Dejan Tomazevic; Franjo Pernus; Bostjan Likar



SAR imaging using the Capon estimator in the 2D subarray processing framework  

NASA Astrophysics Data System (ADS)

We develop a 2D subarray processing technique as an extension of 1D subarray processing to form the image of an inverse synthetic aperture radar (ISAR). By using the 2D processing based on the Capon's spectral estimation method, a high resolution image can be obtained as compared with the conventional Fourier transform and the 1D subarray based method. Our method minimizes the mean output power as much as possible to minimize the interference energy, while the desired scatterer's energy is preserved by using the constraint. Some simulation results are given to demonstrate the performance of the proposed method.

Kim, Soohong; Chun, Joohwan



A 2-D orientation-adaptive prediction filter in lifting structures for image coding.  


Lifting-style implementations of wavelets are widely used in image coders. A two-dimensional (2-D) edge adaptive lifting structure, which is similar to Daubechies 5/3 wavelet, is presented. The 2-D prediction filter predicts the value of the next polyphase component according to an edge orientation estimator of the image. Consequently, the prediction domain is allowed to rotate +/-45 degrees in regions with diagonal gradient. The gradient estimator is computationally inexpensive with additional costs of only six subtractions per lifting instruction, and no multiplications are required. PMID:16435541

Gerek, Omer N; Cetin, A Enis



Multiresolution image representation using combined 2-D and 1-D directional filter banks.  


In this paper, effective multiresolution image representations using a combination of 2-D filter bank (FB) and directional wavelet transform (WT) are presented. The proposed methods yield simple implementation and low computation costs compared to previous 1-D and 2-D FB combinations or adaptive directional WT methods. Furthermore, they are nonredundant transforms and realize quad-tree like multiresolution representations. In applications on nonlinear approximation, image coding, and denoising, the proposed filter banks show visual quality improvements and have higher PSNR than the conventional separable WT or the contourlet. PMID:19095538

Tanaka, Yuichi; Ikehara, Masaaki; Nguyen, Truong Q



Speckle suppression in SAR images using the 2-D GARCH model.  


A novel Bayesian-based speckle suppression method for Synthetic Aperture Radar ( SAR) images is presented that preserves the structural features and textural information of the scene. First, the logarithmic transform of the original image is analyzed into the multiscale wavelet domain. We show that the wavelet coefficients of SAR images have significantly non-Gaussian statistics that are best described by the 2-D GARCH model. By using the 2-D GARCH model on the wavelet coefficients, we are capable of taking into account important characteristics of wavelet coefficients, such as heavy tailed marginal distribution and the dependencies between the coefficients. Furthermore, we use a maximum a posteriori (MAP) estimator for estimating the clean image wavelet coefficients. Finally, we compare our proposed method with various speckle suppression methods applied on synthetic and actual SAR images and we verify the performance improvement in utilizing the new strategy. PMID:19126469

Amirmazlaghani, Maryam; Amindavar, Hamidreza; Moghaddamjoo, Alireza



Nanohole-array-based device for 2D snapshot multispectral imaging.  


We present a two-dimensional (2D) snapshot multispectral imager that utilizes the optical transmission characteristics of nanohole arrays (NHAs) in a gold film to resolve a mixture of input colors into multiple spectral bands. The multispectral device consists of blocks of NHAs, wherein each NHA has a unique periodicity that results in transmission resonances and minima in the visible and near-infrared regions. The multispectral device was illuminated over a wide spectral range, and the transmission was spectrally unmixed using a least-squares estimation algorithm. A NHA-based multispectral imaging system was built and tested in both reflection and transmission modes. The NHA-based multispectral imager was capable of extracting 2D multispectral images representative of four independent bands within the spectral range of 662?nm to 832?nm for a variety of targets. The multispectral device can potentially be integrated into a variety of imaging sensor systems. PMID:24005065

Najiminaini, Mohamadreza; Vasefi, Fartash; Kaminska, Bozena; Carson, Jeffrey J L



RS-2D: CCD readout system for streak cameras and other scientific imaging  

NASA Astrophysics Data System (ADS)

The RS-2D system is intended for various scientific applications, mainly for pulse image capturing. The intrinsic flexibility of CCDs is supported by fully programmable hardware and dedicated control software producing user-friendly, simple to use still powerful measurement device. The evolution of the system, inspired primarily by the need of various scientific experiments led us to a number of techniques and tricks which improve the reliability and precision of data. The RS-2D software is a combination of visualization and measurement tools, general readout control and some specific hardware-oriented procedures. As a result, the software can be used stand- alone just for image analyzing (and sometimes is), it can be adapted for various third-party readout systems (e.g. for Data Translation Frame grabber) but it gives more possibilities when used in RS-2D system. In this article we would also discuss parameters and measurement techniques for CCD readout systems.

Vyssogorets, Mikhail V.; Abrosimov, S. A.; Schelev, Mikhail Y.; Serov, R. V.



Parameterising root system growth models using 2D neutron radiography images  

NASA Astrophysics Data System (ADS)

Root architecture is a key factor for plant acquisition of water and nutrients from soil. In particular in view of a second green revolution where the below ground parts of agricultural crops are important, it is essential to characterise and quantify root architecture and its effect on plant resource acquisition. Mathematical models can help to understand the processes occurring in the soil-plant system, they can be used to quantify the effect of root and rhizosphere traits on resource acquisition and the response to environmental conditions. In order to do so, root architectural models are coupled with a model of water and solute transport in soil. However, dynamic root architectural models are difficult to parameterise. Novel imaging techniques such as x-ray computed tomography, neutron radiography and magnetic resonance imaging enable the in situ visualisation of plant root systems. Therefore, these images facilitate the parameterisation of dynamic root architecture models. These imaging techniques are capable of producing 3D or 2D images. Moreover, 2D images are also available in the form of hand drawings or from images of standard cameras. While full 3D imaging tools are still limited in resolutions, 2D techniques are a more accurate and less expensive option for observing roots in their environment. However, analysis of 2D images has additional difficulties compared to the 3D case, because of overlapping roots. We present a novel algorithm for the parameterisation of root system growth models based on 2D images of root system. The algorithm analyses dynamic image data. These are a series of 2D images of the root system at different points in time. Image data has already been adjusted for missing links and artefacts and segmentation was performed by applying a matched filter response. From this time series of binary 2D images, we parameterise the dynamic root architecture model in the following way: First, a morphological skeleton is derived from the binary images by a closing and a thinning step. Then, a weighted graph is produced from this skeleton, where root tips and branch points are the nodes of the graph. For each connecting edge, the pixel coordinates are stored in a list. Finally, a root system growth model is used to determine individual roots within the graph. In this way, the sequential appearance of each sub-branch is maintained. We demonstrate the use of this algorithm to determine parameters for the root system growth model of Leitner et al. (2010). We use 2D radiography images of Lupine plants. Parameters that are gained from the images include the length of the apical and basal zones, the internodal distances, the number of branches per root, the branching angels, the root radii, and the root growth rate. Computed parameter values are means of four replicates, i.e. the means over four root systems grown under the same conditions. The root systems were classified according to their branching order, and average parameter values were determined for each root order. Based on these parameters, the dynamics of root system growth can be recaptured and analysed.

Schnepf, Andrea; Felderer, Bernd; Vontobel, Peter; Leitner, Daniel



Automatic 2D-to-3D image conversion using 3D examples from the internet  

NASA Astrophysics Data System (ADS)

The availability of 3D hardware has so far outpaced the production of 3D content. Although to date many methods have been proposed to convert 2D images to 3D stereopairs, the most successful ones involve human operators and, therefore, are time-consuming and costly, while the fully-automatic ones have not yet achieved the same level of quality. This subpar performance is due to the fact that automatic methods usually rely on assumptions about the captured 3D scene that are often violated in practice. In this paper, we explore a radically different approach inspired by our work on saliency detection in images. Instead of relying on a deterministic scene model for the input 2D image, we propose to "learn" the model from a large dictionary of stereopairs, such as YouTube 3D. Our new approach is built upon a key observation and an assumption. The key observation is that among millions of stereopairs available on-line, there likely exist many stereopairs whose 3D content matches that of the 2D input (query). We assume that two stereopairs whose left images are photometrically similar are likely to have similar disparity fields. Our approach first finds a number of on-line stereopairs whose left image is a close photometric match to the 2D query and then extracts depth information from these stereopairs. Since disparities for the selected stereopairs differ due to differences in underlying image content, level of noise, distortions, etc., we combine them by using the median. We apply the resulting median disparity field to the 2D query to obtain the corresponding right image, while handling occlusions and newly-exposed areas in the usual way. We have applied our method in two scenarios. First, we used YouTube 3D videos in search of the most similar frames. Then, we repeated the experiments on a small, but carefully-selected, dictionary of stereopairs closely matching the query. This, to a degree, emulates the results one would expect from the use of an extremely large 3D repository. While far from perfect, the presented results demonstrate that on-line repositories of 3D content can be used for effective 2D-to-3D image conversion. With the continuously increasing amount of 3D data on-line and with the rapidly growing computing power in the cloud, the proposed framework seems a promising alternative to operator-assisted 2D-to-3D conversion.

Konrad, J.; Brown, G.; Wang, M.; Ishwar, P.; Wu, C.; Mukherjee, D.



Multichannel 2-D pattern transfer model based on imaging optics for submarine laser uplink communication  

Microsoft Academic Search

An optical communication scheme of 2-D pattern transfer based on imaging optics for submarine laser uplink communication (SLUC) is suggested. Unlike the methods aiming at avoiding neighboring crosstalk used in traditional multi-channel optical beam transferring, we make full use of the overlapping of each spreading beam other than controlling divergence effect of each beam to avoid interference noise. The apparent

Wei Lu; Liren Liu; Jianfeng Sun; Weiqing Pan



2-D Fitting and Interpolation Applied to Image-Distortion Analysis.  

National Technical Information Service (NTIS)

A practical method for distortion analysis was developed by imaging an array of points objects, the pattern of which is known, but with unknown actual locations. A 2D fitting to the discrete pattern estimates the true locations of the point objects, from ...

A. B. Brill G. W. Bennett I. G. Zubal R. W. Rowe Y. Bizais



Photoacoustic imaging for deep targets in the breast using a multichannel 2D array transducer  

Microsoft Academic Search

A photoacoustic (PA) imaging system was developed to achieve high sensitivity for the detection and characterization of vascular anomalies in the breast in the mammographic geometry. Signal detection from deep in the breast was achieved by a broadband 2D PVDF planar array that has a round shape with one side trimmed straight to improve fit near the chest wall. This

Zhixing Xie; Xueding Wang; Richard F. Morris; Frederic R. Padilla; Gerald L. Lecarpentier; Paul L. Carson



Intensity-Based 2D-3D Spine Image Registration Incorporating a Single Fiducial Marker1  

Microsoft Academic Search

Rationale and Objectives. The two-dimensional (2D)-three dimensional (3D) registration of a computed tomography im- age to one or more x-ray projection images has a number of image-guided therapy applications. In general, fiducial mark- er-based methods are fast, accurate, and robust, but marker implantation is not always possible, often is considered too invasive to be clinically acceptable, and entails risk. There

Daniel B. Russakoff; Torsten Rohlfing; John R. Adler Jr; Calvin R. Maurer Jr


Quantification of 3-D field effects during 2-D microwave imaging  

Microsoft Academic Search

Two-dimensional (2-D) approaches to microwave imaging have dominated the research landscape primarily due to the moderate levels of measurement data, data-acquisition time, and computational costs required. Three-dimensional (3-D) approaches have been investigated in simulation, phantom, and animal experiments. While 3-D approaches are certainly important in terms of the potential to improve image quality, their associated costs are significant at this

Paul M. Meaney; Keith D. Paulsen; Shireen D. Geimer; Shah A. Haider; Margaret W. Fanning



Performance efficient FPGA implementation of parallel 2-D MRI image filtering algorithms using Xilinx system generator  

Microsoft Academic Search

Currently, Field Programmable Gate Array (FPGA) goes beyond the low-level line-by-line hardware description language programming in implementing parallel multidimensional image filtering algorithms. High-level abstract hardware-oriented parallel programming method can structurally bridge this gap. This paper proposes a first step toward such a method to efficiently implement Parallel 2-D MRI image filtering algorithms using the Xilinx system generator. The implementation method

Sami Hasan; Alex Yakovlev; Said Boussakta



3D multiple-point statistics simulation using 2D training images  

NASA Astrophysics Data System (ADS)

One of the main issues in the application of multiple-point statistics (MPS) to the simulation of three-dimensional (3D) blocks is the lack of a suitable 3D training image. In this work, we compare three methods of overcoming this issue using information coming from bidimensional (2D) training images. One approach is based on the aggregation of probabilities. The other approaches are novel. One relies on merging the lists obtained using the impala algorithm from diverse 2D training images, creating a list of compatible data events that is then used for the MPS simulation. The other (s2Dcd) is based on sequential simulations of 2D slices constrained by the conditioning data computed at the previous simulation steps. These three methods are tested on the reproduction of two 3D images that are used as references, and on a real case study where two training images of sedimentary structures are considered. The tests show that it is possible to obtain 3D MPS simulations with at least two 2D training images. The simulations obtained, in particular those obtained with the s2Dcd method, are close to the references, according to a number of comparison criteria. The CPU time required to simulate with the method s2Dcd is from two to four orders of magnitude smaller than the one required by a MPS simulation performed using a 3D training image, while the results obtained are comparable. This computational efficiency and the possibility of using MPS for 3D simulation without the need for a 3D training image facilitates the inclusion of MPS in Monte Carlo, uncertainty evaluation, and stochastic inverse problems frameworks.

Comunian, A.; Renard, P.; Straubhaar, J.



Fiducial-less 2D-3D spine image registration using spine region segmented in CT image  

NASA Astrophysics Data System (ADS)

The target pose (position and orientation) of a spinal lesion can be determined using image registration of a pair of two-dimensional (2D) x-ray projection images and a pre-treatment three-dimensional (3D) CT image. This is useful for detecting, tracking and correcting for patient movement during image-guided spinal radiotherapy and radiosurgery. We recently developed a fiducial-less 2D-3D spine image registration that localizes spinal targets by directly tracking adjacent skeletal structures and thereby eliminates the need for implanted fiducials. Experience has shown this method to be robust under a wide range of clinical circumstances. However, image artifacts in digitally reconstructed radiographs (DRRs) that can be introduced by breathing during CT scanning or by other surrounding structures such as ribs have the negative effects on image registration performance. Therefore, we present an approach to eliminate the image artifacts in DRRs for a more robust registration. The spinal structures in the CT volume are approximately segmented in a semi-automatic way and saved as a volume of interest (VOI). The DRRs are then generated within the spine VOI for two orthogonal projections. During radiation treatment delivery, two X-ray images are acquired simultaneously in near real time. Then each X-ray image is registered with the DRR image to obtain 2D local displacements of skeletal structures. The 3D tumor position is calculated from the 2D displacements by 2D-to-3D back-projection and geometric transformation. Experiments on clinical data were conducted to evaluate the performance of the improved registration. The results showed that spine segmentation substantially improves image registration performance.

Fu, Dongshan; Wang, Hongwu; Maurer, Calvin R., Jr.; Kuduvalli, Gopinath



Robust 2D phase correction for echo planar imaging under a tight field-of-view.  


Nyquist ghost artifacts are a serious issue in echo planar imaging. These artifacts primarily originate from phase difference between even and odd echo images and can be removed or reduced using phase correction methods. The commonly used 1D phase correction can only correct phase difference along readout axis. 2D correction is, therefore, necessary when phase difference presents along both readout and phase encoding axes. However, existing 2D methods have several unaddressed issues that affect their practicality. These issues include uncharacterized noise behavior, image artifact due to unoptimized phase estimation, Gibbs ringing artifact when directly applying to partial k(y) data, and most seriously a new image artifact under tight field-of-view (i.e., field-of-view slightly smaller than object size). All these issues are addressed in this article. Specifically, theoretical analysis of noise amplification and effect of phase estimation error is provided, and tradeoff between noise and ghost is studied. A new 2D phase correction method with improved polynomial fitting, joint homodyne processing and phase correction, compatibility with tight field-of-view is then proposed. Various results show that the proposed method can robustly generate images free of Nyquist ghosts and other image artifacts even in oblique scans or when cross-term eddy current terms are significant. PMID:20806354

Xu, Dan; King, Kevin F; Zur, Yuval; Hinks, R Scott



Research on 2D representation method of wireless Micro-Ball endoscopic images.  


Nowadays the interpretation of the images acquired by wireless endoscopy system is a tedious job for doctors. A viable solution is to construct a map, which is the 2D representation of gastrointestinal (GI) tract to reduce the redundancy of images and improve the understandability of them. The work reported in this paper addresses the problem of the 2D representation of GI tract based on a new wireless Micro-Ball endoscopy system with multiple image sensors. This paper firstly models the problem of constructing the map, and then discusses mainly on the issues of perspective distortion correction, image preprocessing and image registration, which lie in the whole problem. The perspective distortion correction algorithm is realized based on attitude angles, while the image registration is based on phase correlation method (PCM) and scale invariant feature transform (SIFT) combined with particular image preprocessing methods. Based on R channels of images, the algorithm can deal with 26.3% to 100% of image registration when the ratio of overlap varies from 25% to 80%. The performance and effectiveness of the algorithms are verified by experiments. PMID:23366099

Wang, Dan; Xie, Xiang; Li, Guolin; Gu, Yingke; Yin, Zheng; Wang, Zhihua



A Wavelet Relational Fuzzy C-Means Algorithm for 2D Gel Image Segmentation  

PubMed Central

One of the most famous algorithms that appeared in the area of image segmentation is the Fuzzy C-Means (FCM) algorithm. This algorithm has been used in many applications such as data analysis, pattern recognition, and image segmentation. It has the advantages of producing high quality segmentation compared to the other available algorithms. Many modifications have been made to the algorithm to improve its segmentation quality. The proposed segmentation algorithm in this paper is based on the Fuzzy C-Means algorithm adding the relational fuzzy notion and the wavelet transform to it so as to enhance its performance especially in the area of 2D gel images. Both proposed modifications aim to minimize the oversegmentation error incurred by previous algorithms. The experimental results of comparing both the Fuzzy C-Means (FCM) and the Wavelet Fuzzy C-Means (WFCM) to the proposed algorithm on real 2D gel images acquired from human leukemias, HL-60 cell lines, and fetal alcohol syndrome (FAS) demonstrate the improvement achieved by the proposed algorithm in overcoming the segmentation error. In addition, we investigate the effect of denoising on the three algorithms. This investigation proves that denoising the 2D gel image before segmentation can improve (in most of the cases) the quality of the segmentation.

Rashwan, Shaheera; Faheem, Mohamed Talaat; Sarhan, Amany; Youssef, Bayumy A. B.



A fast convolution-based methodology to simulate 2-D/3-D cardiac ultrasound images.  


This paper describes a fast convolution-based methodology for simulating ultrasound images in a 2-D/3-D sector format as typically used in cardiac ultrasound. The conventional convolution model is based on the assumption of a space-invariant point spread function (PSF) and typically results in linear images. These characteristics are not representative for cardiac data sets. The spatial impulse response method (IRM) has excellent accuracy in the linear domain; however, calculation time can become an issue when scatterer numbers become significant and when 3-D volumetric data sets need to be computed. As a solution to these problems, the current manuscript proposes a new convolution-based methodology in which the data sets are produced by reducing the conventional 2-D/3-D convolution model to multiple 1-D convolutions (one for each image line). As an example, simulated 2-D/3-D phantom images are presented along with their gray scale histogram statistics. In addition, the computation time is recorded and contrasted to a commonly used implementation of IRM (Field II). It is shown that COLE can produce anatomically plausible images with local Rayleigh statistics but at improved calculation time (1200 times faster than the reference method). PMID:19251529

Gao, Hang; Choi, Hon Fai; Claus, Piet; Boonen, Steven; Jaecques, Siegfried; Van Lenthe, G Harry; Van der Perre, Georges; Lauriks, Walter; D'hooge, Jan



Effective Temperature of 2D Dusty Plasma Liquids at the Discrete Level  

NASA Astrophysics Data System (ADS)

Fluctuation-dissipation theory has been used to measure the effective temperature of non-equilibrium system. In this work, using a 2D dusty plasma liquid formed by the negatively charged fine particles suspending in weakly ionized discharges and sheared by two CW counter parallel laser beams, we measure the micro-transport at the kinetic level. The effective temperatures Teff at different time scales are obtained through the Stokes-Einstein relation which relates the diffusion coefficient (D) and the viscosity (?). The external energy is cascaded from the slow hopping modes to the fast caging modes through mutual coupling, which leads to the higher effective temperature of the slow hopping modes.

Io, Chong-Wai; Chan, Chia-Ling; I, Lin



Intensity-based registration algorithm for probabilistic images and its application for 2D to 3D image registration  

NASA Astrophysics Data System (ADS)

Registration of 2-D projection images and 3-D volume images is still a largely unsolved problem. In order to register a pre-operative CT image to an intra-operative 2-D x-ray image, one typically computes simulated x-ray images from the attenuation coefficients in the CT image (Digital Reconstructed Radiograph, DRR). The simulated images are then compared to the actual image using intensity-based similarity measures to quantify the correctness of the current relative pose. However, the spatial information present in the CT is lost in the process of computing projections. This paper first introduces a probabilistic extension to the computation of DRRs that preserves much of the spatial separability of tissues along the simulated rays. In order to handle the resulting non-scalar data in intensity-based registration, we propose a way of computing entropy-based similarity measures such as mutual information (MI) from probabilistic images. We give an initial evaluation of the feasibility of our novel image similarity measure for 2-D to 3-D registration by registering a probabilistic DRR to a deterministic DRR computed from patient data used in frameless stereotactic radiosurgery.

Rohlfing, Torsten; Russakoff, Daniel B.; Murphy, Martin J.; Maurer, Calvin R.



Intra-cardiac 2D US to 3D CT image registration  

NASA Astrophysics Data System (ADS)

Intra-cardiac echocardiography (ICE) is commonly used to guide intra-cardiac procedures, such as the treatment of atrial fibrillation (AF). However, effective surgical navigation based on ICE images is not trivial, due to the low signal-to-noise ratio (SNR) and limited field of view of ultrasound (US) images. The interpretation of ICE can be significantly improved if correctly placed in the context of three-dimensional magnetic resonance (MR) or computed tomography (CT) images by simultaneously presenting the complementary anatomical information from the two modalities. The purpose of this research is to demonstrate the feasibility of multimodality image registration of 2D intra-cardiac US images with 3D computed tomography (CT) images. In our previous work, a two-step registration procedure has been proposed to register US images with MR images and was validated on a patient dataset. In this work, we extend the two-step method to intra-cardiac procedures and provide a detailed assessment of registration accuracy by determining the target registration errors (TRE) on a heart phantom, which had fiducial markers affixed to the surface to facilitate evaluation of registration accuracy. The resultant TRE on the heart phantom was 3.7 mm. This result is considered to be acceptable for guiding a probe in the heart during ablative therapy for atrial fibrillation. To our knowledge, there is no previous report describing multimodality registration of 2D intra-cardiac US to high-resolution 3D CT.

Huang, Xishi; Hill, Nicholas A.; Ren, Jing; Guiraudon, Gerard; Peters, Terry M.



Localization and tracking of aortic valve prosthesis in 2D fluoroscopic image sequences  

NASA Astrophysics Data System (ADS)

This paper presents a new method for localization and tracking of the aortic valve prosthesis (AVP) in 2D fluoroscopic image sequences to assist the surgeon to reach the safe zone of implantation during transapical aortic valve implantation. The proposed method includes four main steps: First, the fluoroscopic images are preprocessed using a morphological reconstruction and an adaptive Wiener filter to enhance the AVP edges. Second, a target window, defined by a user on the first image of the sequences which includes the AVP, is tracked in all images using a template matching algorithm. In a third step the corners of the AVP are extracted based on the AVP dimensions and orientation in the target window. Finally, the AVP model is generated in the fluoroscopic image sequences. Although the proposed method is not yet validated intraoperatively, it has been applied to different fluoroscopic image sequences with promising results.

Karar, M.; Chalopin, C.; Merk, D. R.; Jacobs, S.; Walther, T.; Burgert, O.; Falk, V.



Solid H2/D2 Particle Seeding and Injection System for Particle Image Velocimetry (PIV) Measurement of He II  

SciTech Connect

Solid particles of the mixture of hydrogen and deuterium have certain advantages for use in Particle Image Velocimetry (PIV) of He II flow. The H2/D2 particles are near neutrally buoyant in He II and will vaporize with the helium as the experimental apparatus is warmed to room temperature. Progress of the construction of a H2/D2 particle seeding and injection system is reported in this paper. A cryogenic pulse valve is used to inject the mixture of helium, hydrogen and deuterium gas directly into a He II bath. Experiments show that the seeding quality is dependent on the back pressure, the mix ratio of the deuterium and helium gases and valve open duration. The effects of these parameters on the solid deuterium particle distribution are also discussed.

Xu, T.; Van Sciver, S. W. [National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida, 32310 (United States); Mechanical Engineering Department, FAMU-FSU College of Engineering, Tallahassee, Florida, 32310 (United States)



The near-field processing for a 2-D narrow imaging algorithm  

Microsoft Academic Search

This paper proposes a novel approximation for the round-trip distance of the near-field echoed data based on a planar 2-D synthetic aperture planar array. A near-field narrow imaging algorithm based on the novel approximation is proposed. Comparisons of the proposed approximation and the Fresnel approximation are also demonstrated. The errors of the proposed approximation are negligible when the antenna is

Pengcheng Gong; Jingquan Zhou; Ling Wang; Zhenhai Shao; Linli Cui; Xueyong Zhu



Image quality vs. NEC in 2D and 3D PET  

Microsoft Academic Search

To investigate the relationship between NEC and image quality to 2D and 3D PET, while simultaneously optimizing 3D low energy threshold (LET), we have performed a series of phantom measurements. The phantom consisted of 46 1 cm fillable hollow spheres on a random grid inside a water-filled oval cylinder, 21 cm tall, 36 cm wide, and 40 cm long. The

John W. Wilson; Timothy G. Turkington; Josh M. Wilson; James G. Colsher; Steven G. Ross



Fluid Structure and Motion Analysis from Multi-spectrum 2D Cloud Image Sequences  

Microsoft Academic Search

In this paper we present a novel approach to estimateand analyze 3D fluid structure and motion ofclouds from multi-spectrum 2D cloud image sequences.Accurate cloud-top structure and motion are very importantfor a host of meteorological and climate applications.However, due to the extremely complex natureof cloud fluid motion, classical nonrigid motion analysismethods will be insufficient to solve this particularproblem. In this paper,

Lin Zhou; Chandra Kambhamettu; Dmitry B. Goldgof



Night vision image fusion for target detection with improved 2D maximum entropy segmentation  

NASA Astrophysics Data System (ADS)

Infrared and LLL image are used for night vision target detection. In allusion to the characteristics of night vision imaging and lack of traditional detection algorithm for segmentation and extraction of targets, we propose a method of infrared and LLL image fusion for target detection with improved 2D maximum entropy segmentation. Firstly, two-dimensional histogram was improved by gray level and maximum gray level in weighted area, weights were selected to calculate the maximum entropy for infrared and LLL image segmentation by using the histogram. Compared with the traditional maximum entropy segmentation, the algorithm had significant effect in target detection, and the functions of background suppression and target extraction. And then, the validity of multi-dimensional characteristics AND operation on the infrared and LLL image feature level fusion for target detection is verified. Experimental results show that detection algorithm has a relatively good effect and application in target detection and multiple targets detection in complex background.

Bai, Lian-fa; Liu, Ying-bin; Yue, Jiang; Zhang, Yi



Fully automatic detection of the vertebrae in 2D CT images  

NASA Astrophysics Data System (ADS)

Knowledge about the vertebrae is a valuable source of information for several annotation tasks. In recent years, the research community spent a considerable effort for detecting, segmenting and analyzing the vertebrae and the spine in various image modalities like CT or MR. Most of these methods rely on prior knowledge like the location of the vertebrae or other initial information like the manual detection of the spine. Furthermore, the majority of these methods require a complete volume scan. With the existence of use cases where only a single slice is available, there arises a demand for methods allowing the detection of the vertebrae in 2D images. In this paper, we propose a fully automatic and parameterless algorithm for detecting the vertebrae in 2D CT images. Our algorithm starts with detecting candidate locations by taking the density of bone-like structures into account. Afterwards, the candidate locations are extended into candidate regions for which certain image features are extracted. The resulting feature vectors are compared to a sample set of previously annotated and processed images in order to determine the best candidate region. In a final step, the result region is readjusted until convergence to a locally optimal position. Our new method is validated on a real world data set of more than 9 329 images of 34 patients being annotated by a clinician in order to provide a realistic ground truth.

Graf, Franz; Kriegel, Hans-Peter; Schubert, Matthias; Strukelj, Michael; Cavallaro, Alexander



Image quality of up-converted 2D video from frame-compatible 3D video  

NASA Astrophysics Data System (ADS)

In the stereoscopic frame-compatible format, the separate high-definition left and high-definition right views are reduced in resolution and packed to fit within the same video frame as a conventional two-dimensional high-definition signal. This format has been suggested for 3DTV since it does not require additional transmission bandwidth and entails only small changes to the existing broadcasting infrastructure. In some instances, the frame-compatible format might be used to deliver both 2D and 3D services, e.g., for over-the-air television services. In those cases, the video quality of the 2D service is bound to decrease since the 2D signal will have to be generated by up-converting one of the two views. In this study, we investigated such loss by measuring the perceptual image quality of 1080i and 720p up-converted video as compared to that of full resolution original 2D video. The video was encoded with either a MPEG-2 or a H.264/AVC codec at different bit rates and presented for viewing with either no polarized glasses (2D viewing mode) or with polarized glasses (3D viewing mode). The results confirmed a loss of video quality of the 2D video up-converted material. The loss due to the sampling processes inherent to the frame-compatible format was rather small for both 1080i and 720p video formats; the loss became more substantial with encoding, particularly for MPEG-2 encoding. The 3D viewing mode provided higher quality ratings, possibly because the visibility of the degradations was reduced.

Speranza, Filippo; Tam, Wa James; Vázquez, Carlos; Renaud, Ronald; Blanchfield, Phil



Spectral-based 2D/3D X-ray to CT image rigid registration  

NASA Astrophysics Data System (ADS)

We present a spectral-based method for the 2D/3D rigid registration of X-ray images to a CT scan. The method uses a Fourier-based representation to decompose the six rigid transformation parameters problem into a twoparameter out-of-plane rotation and a four-parameter in-plane transformation problems. Preoperatively, a set of Digitally Reconstructed Radiographs (DRRs) are generated offline from the CT in the expected in-plane location ranges of the fluoroscopic X-ray imaging devices. Each DRR is transformed into a imaging device in-plane invariant features space. Intraoperatively, a few 2D projections of the patient anatomy are acquired with an X-ray imaging device. Each projection is transformed into its in-plane invariant representation. The out-of-plane parameters are first computed by maximization of the Normalized Cross-Correlation between the invariant representations of the DRRs and the X-ray images. Then, the in-plane parameters are computed with the phase correlation method based on the Fourier-Mellin transform. Experimental results on publicly available data sets show that our method can robustly estimate the out-of-plane parameters with accuracy of 1.5° in less than 1sec for out-of-plane rotations of 10° or more, and perform the entire registration in less than 10secs.

Freiman, M.; Pele, O.; Hurvitz, A.; Werman, M.; Joskowicz, L.



Deep tissue photoacoustic imaging using a miniaturized 2-D capacitive micromachined ultrasonic transducer array.  


In this paper, we demonstrate 3-D photoacoustic imaging (PAI) of light absorbing objects embedded as deep as 5 cm inside strong optically scattering phantoms using a miniaturized (4 mm × 4 mm × 500 ?m), 2-D capacitive micromachined ultrasonic transducer (CMUT) array of 16 × 16 elements with a center frequency of 5.5 MHz. Two-dimensional tomographic images and 3-D volumetric images of the objects placed at different depths are presented. In addition, we studied the sensitivity of CMUT-based PAI to the concentration of indocyanine green dye at 5 cm depth inside the phantom. Under optimized experimental conditions, the objects at 5 cm depth can be imaged with SNR of about 35 dB and a spatial resolution of approximately 500 ?m. Results demonstrate that CMUTs with integrated front-end amplifier circuits are an attractive choice for achieving relatively high depth sensitivity for PAI. PMID:22249594

Kothapalli, Sri-Rajasekhar; Ma, Te-Jen; Vaithilingam, Srikant; Oralkan, Omer; Khuri-Yakub, Butrus T; Gambhir, Sanjiv Sam



Multilevel Image Thresholding Based on 2D Histogram and Maximum Tsallis Entropy- A Differential Evolution Approach.  


Multilevel thresholding amounts to segmenting a gray-level image into several distinct regions. This paper presents a 2D histogram based multilevel thresholding approach to improve the separation between objects. Recent studies indicate that the results obtained with 2D histogram oriented approaches are superior to those obtained with 1D histogram based techniques in the context of bi-level thresholding. Here, a method to incorporate 2D histogram related information for generalized multilevel thresholding is proposed using the maximum Tsallis entropy. Differential evolution (DE), a simple yet efficient evolutionary algorithm of current interest, is employed to improve the computational efficiency of the proposed method. The performance of DE is investigated extensively through comparison with other well-known nature inspired global optimization techniques such as genetic algorithm, particle swarm optimization, artificial bee colony, and simulated annealing. In addition, the outcome of the proposed method is evaluated using a well known benchmark-the Berkley segmentation data set (BSDS300) with 300 distinct images. PMID:23955760

Sarkar, Soham; Das, Swagatam



Whole-heart coronary MR angiography with 2D self-navigated image reconstruction.  


Several self-navigation techniques have been proposed to improve respiratory motion compensation in coronary MR angiography. In this work, we implemented a 2D self-navigation method by using the startup profiles of a whole-heart balanced Steady-state free precession sequence, which are primarily used to catalyze the magnetization towards the steady-state. To create 2D self-navigation images (2DSN), we added phase encoding gradients to the startup profiles. With this approach we calculated foot-head and left-right motion and performed retrospective translational motion correction. The 2DSN images were reconstructed from 10 startup profiles acquired at the beginning of each shot. Nine healthy subjects were scanned, and the proposed method was compared to a 1D self-navigation (1DSN) method with foot-head correction only. Foot-head correction was also performed with the diaphragmatic 1D pencil beam navigator (1Dnav) using a tracking factor of 0.6. 2DSN shows improved motion correction compared to 1DSN and 1Dnav for all coronary arteries and all subjects for the investigated diaphragmatic gating window of 10 mm. The visualized vessel length of the right coronary artery could be significantly improved with a multiple targeted 2D self-navigation approach, compared to 2DSN method. PMID:21656563

Henningsson, Markus; Koken, Peter; Stehning, Christian; Razavi, Reza; Prieto, Claudia; Botnar, René M



Effective Temperature of 2D Dusty Plasma Liquids at the Discrete Level  

SciTech Connect

Fluctuation-dissipation theory has been used to measure the effective temperature of non-equilibrium system. In this work, using a 2D dusty plasma liquid formed by the negatively charged fine particles suspending in weakly ionized discharges and sheared by two CW counter parallel laser beams, we measure the micro-transport at the kinetic level. The effective temperatures Teff at different time scales are obtained through the Stokes-Einstein relation which relates the diffusion coefficient (D) and the viscosity ({eta}). The external energy is cascaded from the slow hopping modes to the fast caging modes through mutual coupling, which leads to the higher effective temperature of the slow hopping modes.

Io, C.-W.; Chan, C.-L.; I Lin [Department of Physics, National Central University, Jhongli 32001, Taiwan (China)



Room temperature synthesis of 2D CuO nanoleaves in aqueous solution  

NASA Astrophysics Data System (ADS)

A simple room temperature method was reported for the synthesis of CuO nanocrystals in aqueous solution through the sequence of {Cu}^{2+} \\to {Cu(OA)}_{2} \\to {Cu(OH)}_{2} \\to {Cu(OH)}_{4}^{2-}\\allowbreak \\to {CuO} . Sodium oleate (SOA) was used as the surfactant and shape controller. The as-prepared samples were characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), UV-visible absorption spectroscopy (UV-vis) and differential thermal analysis (DTA). It can be seen that 1D Cu(OH)2 nanowires were first obtained from Cu(OA)2 and, at room temperature, converted into 2D CuO nanoleaves (CuO NLs) in a short time under a weakly basic environment. On prolonging the reaction time, the top part of these 2D nanoleaves branched and separated along the long axis to form 1D rod-like nano-CuO because of the assistance of SOA. A possible transformation mechanism of Cu(OH)2 to CuO nanostructures at room temperature in aqueous solution is discussed. The transformation velocity can be controlled by changing the pH value of the system. The prepared CuO NLs were used to construct an enzyme-free glucose sensor. The detecting results showed that the designed sensor exhibited good amperometric responses towards glucose with good anti-interferent ability.

Zhao, Yan; Zhao, Jingzhe; Li, Yunling; Ma, Dechong; Hou, Shengnan; Li, Linzhi; Hao, Xinli; Wang, Zichen



Room temperature synthesis of 2D CuO nanoleaves in aqueous solution.  


A simple room temperature method was reported for the synthesis of CuO nanocrystals in aqueous solution through the sequence of Cu(2+) ? Cu(OA)2 ? Cu(OH)2 ? Cu(OH)(2-)4 ? CuO. Sodium oleate (SOA) was used as the surfactant and shape controller. The as-prepared samples were characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), UV-visible absorption spectroscopy (UV-vis) and differential thermal analysis (DTA). It can be seen that 1D Cu(OH)(2) nanowires were first obtained from Cu(OA)(2) and, at room temperature, converted into 2D CuO nanoleaves (CuO NLs) in a short time under a weakly basic environment. On prolonging the reaction time, the top part of these 2D nanoleaves branched and separated along the long axis to form 1D rod-like nano-CuO because of the assistance of SOA. A possible transformation mechanism of Cu(OH)(2) to CuO nanostructures at room temperature in aqueous solution is discussed. The transformation velocity can be controlled by changing the pH value of the system. The prepared CuO NLs were used to construct an enzyme-free glucose sensor. The detecting results showed that the designed sensor exhibited good amperometric responses towards glucose with good anti-interferent ability. PMID:21297232

Zhao, Yan; Zhao, Jingzhe; Li, Yunling; Ma, Dechong; Hou, Shengnan; Li, Linzhi; Hao, Xinli; Wang, Zichen



Model-to-image based 2D-3D registration of angiographic data  

NASA Astrophysics Data System (ADS)

We propose a novel registration method, which combines well-known vessel detection techniques with aspects of model adaptation. The proposed method is tailored to the requirements of 2D-3D-registration of interventional angiographic X-ray data such as acquired during abdominal procedures. As prerequisite, a vessel centerline is extracted out of a rotational angiography (3DRA) data set to build an individual model of the vascular tree. Following the two steps of local vessel detection and model transformation the centerline model is matched to one dynamic subtraction angiography (DSA) target image. Thereby, the in-plane position and the 3D orientation of the centerline is related to the vessel candidates found in the target image minimizing the residual error in least squares manner. In contrast to feature-based methods, no segmentation of the vessel tree in the 2D target image is required. First experiments with synthetic angiographies and clinical data sets indicate that matching with the proposed model-to-image based registration approach is accurate and robust and is characterized by a large capture range.

Mollus, Sabine; Lübke, Jördis; Walczuch, Andreas J.; Schumann, Heidrun; Weese, Jürgen



Image simulations and galaxy fitting in GEMS and STAGES: GALFIT VS GIM2D  

NASA Astrophysics Data System (ADS)

In the context of big HST surveys, we present extensive and well tested image simulations to derive the survey detection completeness. We elaborate on the reliability of 2D galaxy fitting codes (GALFIT and GIM2D), which are widely used for morphological galaxy classification (especially for galaxies at high redshift), but are rarely tested thoroughly. While both codes perform similarly well on bright, big galaxies in these surveys, we find that GALFIT is more robust on faint and small galaxies, especially when used in the context of GALAPAGOS, a script that automates the fitting process successfully. Furthermore, we show that both codes underestimate the true parameter error bars severely. Whereas a Sérsic index cut is not an ideal tool to distinguish between early- and late-type galaxies it is widely used as such. We will point out potential complications in using such a simple automated cut. [1

Häußler, Boris; Barden, Marco; McIntosh, Daniel H.



An automated algorithm for blood vessel count and area measurement in 2-D choroidal scan images.  


We present an automated algorithm for the detection of blood vessels in 2-D choroidal scan images followed by a measurement of the area of the vessels. The objective is to identify vessel parameters in the choroidal stroma that are affected by various abnormalities. The algorithm is divided into five stages. In the first stage, the image is denoised to remove sensor noise and facilitate further processing. In the second stage, the image is segmented in order to find the region of interest. In the third stage, three different contour detection methods are applied to address different challenges in vessel contour. In the fourth stage, the outputs of the three contour detection methods are combined to achieve refined vessel contour detection. In the fifth and final stage, the area of these contours are measured. The results have been evaluated by a practicing opthalmologist and performance of the algorithm relative to expert detection is reported. PMID:24110447

Mahajan, Nagaraj R; Donapati, Ravi Chandra Reddy; Channappayya, Sumohana S; Vanjari, Sivaramakrishna; Richhariya, Ashutosh; Chhablani, Jay



Visualizing 3D Objects from 2D Cross Sectional Images Displayed "In-Situ" versus "Ex-Situ"  

ERIC Educational Resources Information Center

|The present research investigates how mental visualization of a 3D object from 2D cross sectional images is influenced by displacing the images from the source object, as is customary in medical imaging. Three experiments were conducted to assess people's ability to integrate spatial information over a series of cross sectional images in order to…

Wu, Bing; Klatzky, Roberta L.; Stetten, George



Performance evaluation for 2D and 3D filtering methods of noise removal in color images  

NASA Astrophysics Data System (ADS)

Color images formed by modern digital cameras are often noisy, especially if they are captured in bad illumination conditions. This makes desirable to remove the noise by image pre-filtering. A specific feature of the noise observed for the considered application is that it can be spatially correlated. Filters to be applied have to effectively suppress noise introducing only negligible distortions into processed images. Moreover, such filters have to be fast enough and tested for a variety of natural images and noise properties. Another specific requirement is that a visual quality of processed images has to be paid a specific attention. To carry out intensive testing of some denoising approaches, a recently designed database TID2008 of distorted images provides a good opportunity since it contains 25 different images corrupted by i.i.d. and spatially correlated noise with several levels of variances. Taking into account the known fact that the color components are highly correlated, both modern 2D (component-wise) and 3D (vector) filtering techniques are studied. It is demonstrated that the use of 3D filters that allow exploiting inter-channel correlation provides considerably better results in terms of conventional and visual quality metrics. It is also shown how 3D filter based on discrete cosine transform (DCT) can be adapted to a spatial correlation of noise. This adaptation produces sufficient increase of the filter's efficiency. Examples of filter's performance are presented.

Ponomarenko, Nikolay N.; Lukin, Vladimir V.; Zelensky, Alexander A.; Egiazarian, Karen O.; Astola, Jaakko T.



Cardiac cycle phase estimation in 2-D echocardiographic images using an artificial neural network.  


This paper proposes a new hybrid approach to estimate the cardiac cycle phases in 2-D echocardiographic images as a first step in cardiac volume estimation. We focused on analyzing the atrial systole and diastole events by using the geometrical position of the mitral valve and a set of three image features. The proposed algorithm is based on a tandem of image processing methods and artificial neural networks as a classifier to robustly extract anatomical information. An original set of image features is proposed and derived to recognize the cardiac phases. The aforementioned approach is performed in two denoising scenarios. In the first scenario, the images are corrupted with Gaussian noise, and in the second one with Rayleigh noise distribution. Our hybrid algorithm does not involve any manual tracing of the boundaries for segmentation process. The algorithm is implemented as computer-aided diagnosis (CADi) software. A dataset of 150 images that include both normal and infarct cardiac pathologies was used. We reported an accuracy of 90 % and a 2 ± 0.3 s in terms of execution time of CADi application in a cardiac cycle estimation task. The main contribution of this paper is to propose this hybrid method and a set of image features that can be helpful for automatic detection applications without any user intervention. The results of the employed methods are qualitatively and quantitatively compared in terms of efficiency for both scenarios. PMID:23247838

Bibicu, Dorin; Moraru, Luminita



Marginal space learning for efficient detection of 2D/3D anatomical structures in medical images.  


Recently, marginal space learning (MSL) was proposed as a generic approach for automatic detection of 3D anatomical structures in many medical imaging modalities [1]. To accurately localize a 3D object, we need to estimate nine pose parameters (three for position, three for orientation, and three for anisotropic scaling). Instead of exhaustively searching the original nine-dimensional pose parameter space, only low-dimensional marginal spaces are searched in MSL to improve the detection speed. In this paper, we apply MSL to 2D object detection and perform a thorough comparison between MSL and the alternative full space learning (FSL) approach. Experiments on left ventricle detection in 2D MRI images show MSL outperforms FSL in both speed and accuracy. In addition, we propose two novel techniques, constrained MSL and nonrigid MSL, to further improve the efficiency and accuracy. In many real applications, a strong correlation may exist among pose parameters in the same marginal spaces. For example, a large object may have large scaling values along all directions. Constrained MSL exploits this correlation for further speed-up. The original MSL only estimates the rigid transformation of an object in the image, therefore cannot accurately localize a nonrigid object under a large deformation. The proposed nonrigid MSL directly estimates the nonrigid deformation parameters to improve the localization accuracy. The comparison experiments on liver detection in 226 abdominal CT volumes demonstrate the effectiveness of the proposed methods. Our system takes less than a second to accurately detect the liver in a volume. PMID:19694281

Zheng, Yefeng; Georgescu, Bogdan; Comaniciu, Dorin



GPU accelerated generation of digitally reconstructed radiographs for 2-D/3-D image registration.  


Recent advances in programming languages for graphics processing units (GPUs) provide developers with a convenient way of implementing applications which can be executed on the CPU and GPU interchangeably. GPUs are becoming relatively cheap, powerful, and widely available hardware components, which can be used to perform intensive calculations. The last decade of hardware performance developments shows that GPU-based computation is progressing significantly faster than CPU-based computation, particularly if one considers the execution of highly parallelisable algorithms. Future predictions illustrate that this trend is likely to continue. In this paper, we introduce a way of accelerating 2-D/3-D image registration by developing a hybrid system which executes on the CPU and utilizes the GPU for parallelizing the generation of digitally reconstructed radiographs (DRRs). Based on the advancements of the GPU over the CPU, it is timely to exploit the benefits of many-core GPU technology by developing algorithms for DRR generation. Although some previous work has investigated the rendering of DRRs using the GPU, this paper investigates approximations which reduce the computational overhead while still maintaining a quality consistent with that needed for 2-D/3-D registration with sufficient accuracy to be clinically acceptable in certain applications of radiation oncology. Furthermore, by comparing implementations of 2-D/3-D registration on the CPU and GPU, we investigate current performance and propose an optimal framework for PC implementations addressing the rigid registration problem. Using this framework, we are able to render DRR images from a 256×256×133 CT volume in ~24 ms using an NVidia GeForce 8800 GTX and in ~2 ms using NVidia GeForce GTX 580. In addition to applications requiring fast automatic patient setup, these levels of performance suggest image-guided radiation therapy at video frame rates is technically feasible using relatively low cost PC architecture. PMID:22801484

Dorgham, Osama M; Laycock, Stephen D; Fisher, Mark H



Room- and low-temperature magnetic properties of 2-D magnetite particle arrays  

NASA Astrophysics Data System (ADS)

Palaeomagnetic observations are being used in increasingly sophisticated geological and geophysical interpretations. It is therefore important to test the theories behind palaeomagnetic recording by rocks, and this can only be achieved using samples containing precisely controlled magnetic mineralogy, grain size and interparticle spacing, the last of which controls the degree of magnetostatic interactions within the samples. Here we report the room- and low temperature magnetic behaviour of a set of samples produced by the nano-scale patterning technique electron beam lithography. The samples consist of 2-D arrays of near-identical magnetite dots of various sizes, geometries and spatial configurations, with dot sizes from ranging from near the single domain threshold of 74-333 nm. We have made a series of magnetic measurements including hysteresis, first-order-reversal curve measurements and remanence acquisition, many as a function of temperature between 20 and 300 K, to quantify the samples’ behaviour to routine palaeomagnetic measurement procedures. We have also examined the behaviour of saturation isothermal remanences (SIRM) to cooling and warming cycling of the sample below room temperature. In addition, we investigated the samples’ responses to alternating-field demagnetization of room temperature induced SIRM, anhysteretic remanent magnetization (ARM) and partial ARM. ARM was used as a non-heating analogue for natural thermoremanence. Given the 2-D spatial distribution of the samples, in all the experiments we conducted both in-plane and out-of-plane measurements. Generally, the samples were found to display pseudo-single-domain hysteresis characteristics, but were found to be reliable recorders of weak-field remanences like ARM. For the closely packed samples, the samples’ magnetic response was highly dependent on measurement orientation.

Krása, David; Muxworthy, Adrian R.; Williams, Wyn



AIDA: a software package for 2D model fitting analysis of astronomical images  

NASA Astrophysics Data System (ADS)

AIDA (Astronomical Image Decomposition and Analysis) is a software package originally developed to analyze images of galaxies with a bright nucleus and to perform the decomposition into the nuclear and the galaxy components. The package is able to perform photometrical and morphological study of faint galaxies as well as standard photometry of stellar fields. With the use of graphical interfaces, AIDA assists interactively the user in selecting sources and preparing them for the analysis. Since the decomposition into the galactic and nuclear components, in particular in the case where the nucleus is dominant, requires a careful characterization of the PSF, AIDA has been designed to manage complex 2-D models (both analytical and empirical, or a combinations of them), even variable in the field of view, making it suitable for Adaptive Optics observations. PSF models can be provided by the user or modeled by AIDA itself using reference stars in the images. Relevant parameters of the target sources are then extracted by fitting source models convolved with the PSF. In addition to the standard (interactive) mode AIDA can also perform automatic processing of a large numbers of images, extracting the PSF model from each image and evaluating source parameters for targets (stars, galaxies, AGN or QSO) by model fitting. With this automatic mode, AIDA can process, in a fully automatic way, large datasets of targets distributed in several images.

Uslenghi, Michela; Falomo, Renato



Enhanced detection of the vertebrae in 2D CT-images  

NASA Astrophysics Data System (ADS)

In recent years, a considerable amount of methods have been proposed for detecting and reconstructing the spine and the vertebrae from CT and MR scans. The results are either used for examining the vertebrae or serve as a preprocessing step for further detection and annotation tasks. In this paper, we propose a method for reliably detecting the position of the vertebrae on a single slice of a transversal body CT scan. Thus, our method is not restricted by the available portion of the 3D scan, but even suffices with a single 2D image. A further advantage of our method is that detection does not require adjusting parameters or direct user interaction. Technically, our method is based on an imaging pipeline comprising five steps: The input image is preprocessed. The relevant region of the image is extracted. Then, a set of candidate locations is selected based on bone density. In the next step, image features are extracted from the surrounding of the candidate locations and an instance-based learning approach is used for selecting the best candidate. Finally, a refinement step optimizes the best candidate region. Our proposed method is validated on a large diverse data set of more than 8 000 images and improves the accuracy in terms of area overlap and distance from the true position significantly compared to the only other method being proposed for this task so far.

Graf, Franz; Greil, Robert; Kriegel, Hans-Peter; Schubert, Matthias; Cavallaro, Alexander



2D-CELL: image processing software for extraction and analysis of 2-dimensional cellular structures  

NASA Astrophysics Data System (ADS)

2D-CELL is a software package for the processing and analyzing of photographic images of cellular structures in a largely interactive way. Starting from a binary digitized image, the programs extract the line network (skeleton) of the structure and determine the graph representation that best models it. Provision is made for manually correcting defects such as incorrect node positions or dangling bonds. Then a suitable algorithm retrieves polygonal contours which define individual cells - local boundary curvatures are neglected for simplicity. Using elementary analytical geometry relations, a range of metric and topological parameters describing the population are then computed, organized into statistical distributions and graphically displayed. Presently at: LSG2M-URA159-Ecole des Mines, 54000 Nancy, France.

Righetti, F.; Telley, H.; Leibling, Th. M.; Mocellin, A.



Programmable 2D laser marking device based on a pulsed UV image coherent amplifier  

NASA Astrophysics Data System (ADS)

We present a novel technique for engraving microscopic 2D patterns in one step with a UV pulsed laser by means of a versatile programmable approach. The laser beam is divided to an expanded low energy signal beam which is spatially modulated by a LCD modulator and a higher energy pump beam with a plane homogeneous wave front. Both beams are superposed in a highly magnesium doped photorefractive lithium-niobate crystal where an energy transfer towards the weaker signal beam takes place. The spatially modulated and amplified signal beam is then de-magnified and imaged onto the surface where the image has to be engraved. The need for the coherent amplifier rises out of the fact that LCDs are unable to withstand the high energy throughput required for etching. The combination of the amplifier with the amplitude modulator leads to a faster and more flexible solution than laser marking with pixel-by-pixel raster-scan, or fixed mask projection mode. Such a technique can thus be applied to identify valuable items by imprinting a smart and personalized 2D code onto its surface.

Lamarque, Thierry; Nicolaus, Ralf; Loiseaux, Brigitte; Huignard, Jean-Pierre; Slekys, Gintas; Xu, Jingjun



What shape are dolphins? Building 3D morphable models from 2D images.  


3D morphable models are low-dimensional parameterizations of 3D object classes which provide a powerful means of associating 3D geometry to 2D images. However, morphable models are currently generated from 3D scans, so for general object classes such as animals they are economically and practically infeasible. We show that, given a small amount of user interaction (little more than that required to build a conventional morphable model), there is enough information in a collection of 2D pictures of certain object classes to generate a full 3D morphable model, even in the absence of surface texture. The key restriction is that the object class should not be strongly articulated, and that a very rough rigid model should be provided as an initial estimate of the “mean shape.” The model representation is a linear combination of subdivision surfaces, which we fit to image silhouettes and any identifiable key points using a novel combined continuous-discrete optimization strategy. Results are demonstrated on several natural object classes, and show that models of rather high quality can be obtained from this limited information. PMID:22392707

Cashman, Thomas J; Fitzgibbon, Andrew W



Prospective respiratory motion correction for coronary MR angiography using a 2D image navigator.  


Respiratory motion remains the major impediment in a substantial amount of patients undergoing coronary magnetic resonance angiography. Motion correction in coronary magnetic resonance angiography is typically performed with a diaphragmatic 1D navigator (1Dnav) assuming a constant linear relationship between diaphragmatic and cardiac respiratory motion. In this work, a novel 2D navigator (2Dnav) is proposed, which prospectively corrects for translational motion in foot-head and left-right direction. First, 1Dnav- and 2Dnav-based motion correction are compared in 2D real time imaging experiments, by evaluating the residual respiratory motion in 10 healthy subjects as well as in a moving vessel phantom. Subsequently, 1Dnav and 2Dnav corrected high-resolution 3D coronary MR angiograms were acquired, and both objective and subjective image quality were assessed. For a gating window of 10 mm, 1Dnav and 2Dnav performed equally well; however, without any respiratory gating, the 1Dnav had a lower visual score for all coronary arteries compared with 10 mm gating, whereas the 2Dnav without gating performed similar to 1Dnav with 10 mm gating. PMID:22529009

Henningsson, Markus; Smink, Jouke; Razavi, Reza; Botnar, René M



From 2D to 3D: II. TEM and AFM Images  

NSDL National Science Digital Library

The problems in the accompanying exercises, "From 2D to 3D: Escher drawings", deal with abstractions that can be related to minerals through geometrical features they have in common. However, we are utimately interested in real minerals, their symmetries, and complexities. High-resolution transmission electron microscopy (HRTEM) provides 2-D projections of mineral structures at almost the atomic scale, and atomic force microscopy (AFM) provides 3-D information about the surfaces of minerals. By using these instruments, we can learn about defects in minerals and their complexities. The mineral examples in this problem set include representatives from several silicate structure type, sulfides, a sulfosalt, and a carbonate. Interpretation of the images is less clear-cut than of the idealized drawings. In some cases the results can be ambiguous, but the provide a scope for fruitful discussions among class members. In a few cases, references are given to the published papers from which the images are taken. These can be used to draw students into the professional literature, even though it will not always be possible to arrive at unambiguous answers. These problems should be thought provoking and yet manageable at several levels of complexity.


Groundwater exploration using 2D Resistivity Imaging in Pagoh, Johor, Malaysia  

NASA Astrophysics Data System (ADS)

Groundwater is a very important component of water resources in nature. Since the demand of groundwater increases with population growth, it is necessary to explore groundwater more intensively. In Malaysia only less than 2% of the present water used is developed from groundwater. In order to determine the existence of usable groundwater for irrigation and drinking purposes in Pagoh, 2D resistivity imaging technique was utilized. The 2-D resistivity imaging technique utilized the Wenner-Schlumberger electrode array configuration because this array is moderately sensitive to both horizontal and vertical structures. Three lines were surveyed for groundwater delineation purpose The length for each survey lines are 400 meters. At Pagoh, the survey site shows the existence of groundwater. It is indicated by the resistivity values about 10-100 ohm-m. The maximum depth of investigation survey is 77 meters. In general the results show that the subsurface is made up of alluvium and clay and the high resistivity values of more than 1000 ohm-m near the surface is due laterite and the end of the depth can be interpreted as mixture of weathered material or bedrock.

Kadri, Muhammad; Nawawi, M. N. M.



Low-temperature studies of a 2D Quantum Heisenberg Antiferromagnet  

NASA Astrophysics Data System (ADS)

A recent inelastic neutron scattering experiment of a 2D Quantum Heisenberg Antiferromagnet (2DQHAF) in an applied field [1] revealed novel features in the energy spectrum but the field was limited to 0.3 HSAT due to the exchange strength (J = 17.5 K) of the material under study. (Quinolinium)2CuBr4.2H2O is known [2] to be a molecular-based version of a strongly 2D QHAF with a significantly smaller exchange strength of 6.2 K and a saturation field of 15 T. We report the low-temperature properties (T 1.8 K) of (Quinolinium)2CuBr4.2H2O and discuss its applicability for further investigations.[4pt] [1] N. Tsyrulin, T. Pardina, R. R. P. Singh et al, Phys. Rev. Lett. 102, 197201: 1-4 (2009).[0pt] [2] R. T. Butcher, M. M. Turnbull, C. P. Landee et al, Inorg. Chem. 49, 427-434 (2010).

Landee, Christopher; Xiao, Fan; Turnbull, Mark; Bartolomé, Juan



A Fast Phosphor Imaging Diagnostic for 2D Plasma Fluctuation Measurements  

NASA Astrophysics Data System (ADS)

A plasma imaging diagnostic is being developed using a fast time response ZnO:Zn phosphor disk to image plasma density fluctuations in a two dimensional region in the PISCES-A linear plasma device. The diagnostic is an 8.9 cm diameter phosphor coated aluminum disk enabling one to image the entire cross section of the plasma at one time. The disk is inserted into the plasma and is excited by incident electrons with energy E_e>= 2.5 eV leading to cathodeluminescent photon emission. The phosphor light fluctuations are then interpreted as plasma density fluctuations using sheath theory and the phosphor response function. The local luminance S of fluctuating phosphor light is dependent on the incident electron energy Ee and current density through the equation S=int R(E_e)( v\\cdotn)f_e(v,t)d^3v, where R(E_e) is the energy dependent response function of the phosphor. The phosphor persistence time of 1-10 ?s combined with fast-intensified CCD camera shutter speeds enables the imaging of plasma fluctuations on microsecond time scales. The temporal and spatial resolution of the phosphor imaging diagnostic has allowed us to make 2D plasma turbulence measurements and detect coherent modes. Supported by US DOE Contract DE-FG03-95ER54301

Liebscher, A.; Luckhardt, S.; Antar, G.; Zweben, S.



The concept of 2D gated imaging for particle sizing in a laminar diffusion flame  

NASA Astrophysics Data System (ADS)

In this work, time-resolved laser-induced incandescence (TiRe LII) has been employed to measure primary particle diameters of soot in an atmospheric laminar ethylene diffusion flame. The generated data set complements existing data determined in one single location and takes advantage of the good spatial resolution of the ICCD detection. Time resolution is achieved by shifting the camera gate along the LII decay. One key input parameter for the analysis of time-resolved LII is the local flame temperature. This was determined on a grid throughout the flame by coherent anti-Stokes Raman scattering. The accurate temperature data, in combination with other published data from this flame, are well suited for soot model validation purposes while we showed feasibility of a shifted gate approach to deduce 2D particle sizes in the chosen standard flame.

Hadef, Redjem; Geigle, Klaus Peter; Zerbs, Jochen; Sawchuk, Robert A.; Snelling, David R.



A 2D to 3D ultrasound image registration algorithm for robotically assisted laparoscopic radical prostatectomy  

NASA Astrophysics Data System (ADS)

Robotically assisted laparoscopic radical prostatectomy (RARP) is an effective approach to resect the diseased organ, with stereoscopic views of the targeted tissue improving the dexterity of the surgeons. However, since the laparoscopic view acquires only the surface image of the tissue, the underlying distribution of the cancer within the organ is not observed, making it difficult to make informed decisions on surgical margins and sparing of neurovascular bundles. One option to address this problem is to exploit registration to integrate the laparoscopic view with images of pre-operatively acquired dynamic contrast enhanced (DCE) MRI that can demonstrate the regions of malignant tissue within the prostate. Such a view potentially allows the surgeon to visualize the location of the malignancy with respect to the surrounding neurovascular structures, permitting a tissue-sparing strategy to be formulated directly based on the observed tumour distribution. If the tumour is close to the capsule, it may be determined that the adjacent neurovascular bundle (NVB) needs to be sacrificed within the surgical margin to ensure that any erupted tumour was resected. On the other hand, if the cancer is sufficiently far from the capsule, one or both NVBs may be spared. However, in order to realize such image integration, the pre-operative image needs to be fused with the laparoscopic view of the prostate. During the initial stages of the operation, the prostate must be tracked in real time so that the pre-operative MR image remains aligned with patient coordinate system. In this study, we propose and investigate a novel 2D to 3D ultrasound image registration algorithm to track the prostate motion with an accuracy of 2.68+/-1.31mm.

Esteghamatian, Mehdi; Pautler, Stephen E.; McKenzie, Charles A.; Peters, Terry M.



Ultrasonic imaging of 3D displacement vectors using a simulated 2D array and beamsteering.  


Most quasi-static ultrasound elastography methods image only the axial strain, derived from displacements measured in the direction of ultrasound propagation. In other directions, the beam lacks high resolution phase information and displacement estimation is therefore less precise. However, these estimates can be improved by steering the ultrasound beam through multiple angles and combining displacements measured along the different beam directions. Previously, beamsteering has only considered the 2D case to improve the lateral displacement estimates. In this paper, we extend this to 3D using a simulated 2D array to steer both laterally and elevationally in order to estimate the full 3D displacement vector over a volume. The method is tested on simulated and phantom data using a simulated 6-10MHz array, and the precision of displacement estimation is measured with and without beamsteering. In simulations, we found a statistically significant improvement in the precision of lateral and elevational displacement estimates: lateral precision 35.69?m unsteered, 3.70?m steered; elevational precision 38.67?m unsteered, 3.64?m steered. Similar results were found in the phantom data: lateral precision 26.51?m unsteered, 5.78?m steered; elevational precision 28.92?m unsteered, 11.87?m steered. We conclude that volumetric 3D beamsteering improves the precision of lateral and elevational displacement estimates. PMID:23164173

Housden, R James; Gee, Andrew H; Treece, Graham M; Prager, Richard W



2D photoacoustic scanning imaging with a single pulsed laser diode excitation  

NASA Astrophysics Data System (ADS)

A portable near-infrared photoacoustic scanning imaging system has been developed with a single pulsed laser diode, which was integrated with an optical lens system to straightforward boost the laser energy density for photoacoustic generation. The 905 nm laser diode provides a maximum energy output of 14 ?J within 100 ns pulse duration, and the pulse repetition frequency rate is 0.8 KHz. As a possible alternative light source, the preliminary 2D photoacoustic results primely correspond with the test phantoms of umbonate extravasated gore and knotted blood vessel network. The photoacoustic SNR can reach 20.6+/-1.2 dB while signal averaging reduces to 128 pulses from thousands to tens of thousands times, and the signal acquisition time accelerates to less than 0.2 s in each A-scan, especially the volume of the total radiation source is only 10 × 3 × 3 cm3. It demonstrated that the pulsed semiconductor laser could be a candidate of photoacoustic equipment for daily clinical application.

Chen, Xuegang; Li, Changwei; Zeng, Lvming; Liu, Guodong; Huang, Zhen; Ren, Zhong



Comparison of 2D temperature maps recorded during laser-induced thermal tissue treatment with corresponding temperature distributions calculated from 3D Monte-Carlo simulations  

NASA Astrophysics Data System (ADS)

Minimally invasive techniques often require special biomedical monitoring schemes. In the case of laser coagulation of tumors accurate temperature mapping is desirable for therapy control. While magnetic resonance (MR)-based thermometry can easily yield qualitative results it is still difficult to calibrate this technique with independent temperature probes for the entire 2D field of view. Calculated temperature maps derived from Monte-Carlo simulations (MCS), on the other hand, are suitable for therapy planning and dosimetry but typically can not account for the extract individual tissue parameters and physiological changes upon heating. In this work, online thermometry was combined with MCS techniques to explore the feasibility and potential of such a biomodal approach for surgical assist systems. For the first time, the result of a 3D simulation were evaluated with MR techniques. An MR thermometry system was used to monitor the temperature evolution during laser-induced thermal treatment of bovine liver using a commercially available water-cooled applicator. A systematic comparison between MR-derived 2D temperature maps in different orientations and corresponding snapshots of a 3D MCS of the laser-induced processes is presented. The MCS is capable of resolving the complex temperature patterns observed in the MR-derived images and yields a good agreement with respect to absolute temperatures and damage volume dimensions. The observed quantitative agreement is around 10 degrees C and on the order of 10 percent, respectively. The integrated simulation-and-monitoring approach has the potential to improve surgical assistance during thermal interventions.

Busse, Harald; Bublat, Martin; Ratering, Ralf; Rassek, Margarethe; Schwarzmaier, Hans-Joachim; Kahn, Thomas



Numerical simulation of 2D buoyant jets in ice-covered and temperature-stratified water  

NASA Astrophysics Data System (ADS)

A two-dimensional (2D) unsteady simulation model is applied to the problem of a submerged warm water discharge into a stratified lake or reservoir with an ice cover. Numerical simulations and analyses are conducted to gain insight into large-scale convective recirculation and flow processes in a cold waterbody induced by a buoyant jet. Jet behaviors under various discharge temperatures are captured by directly modeling flow and thermal fields. Flow structures and processes are described by the simulated spatial and temporal distributions of velocity and temperature in various regions: deflection, recirculation, attachment, and impingement. Some peculiar hydrothermal and dynamic features, e.g. reversal of buoyancy due to the dilution of a warm jet by entraining cold ambient water, are identified and examined. Simulation results show that buoyancy is the most important factor controlling jet behavior and mixing processes. The inflow boundary is treated as a liquid wall from which the jet is offset. Similarity and difference in effects of boundaries perpendicular and parallel to flow, and of buoyancy on jet attachment and impingement, are discussed. Symmetric flow configuration is used to de-emphasize the Coanda effect caused by offset.

Gu, Ruochuan


Image inpainting on the basis of spectral structure from 2-D nonharmonic analysis.  


The restoration of images by digital inpainting is an active field of research and such algorithms are, in fact, now widely used. Conventional methods generally apply textures that are most similar to the areas around the missing region or use a large image database. However, this produces discontinuous textures and thus unsatisfactory results. Here, we propose a new technique to overcome this limitation by using signal prediction based on the nonharmonic analysis (NHA) technique proposed by the authors. NHA can be used to extract accurate spectra, irrespective of the window function, and its frequency resolution is less than that of the discrete Fourier transform. The proposed method sequentially generates new textures on the basis of the spectrum obtained by NHA. Missing regions from the spectrum are repaired using an improved cost function for 2D NHA. The proposed method is evaluated using the standard images Lena, Barbara, Airplane, Pepper, and Mandrill. The results show an improvement in MSE of about 10-20 compared with the examplar-based method and good subjective quality. PMID:23549889

Hasegawa, Masaya; Kako, Takahiro; Hirobayashi, Shigeki; Misawa, Tadanobu; Yoshizawa, Toshio; Inazumi, Yasuhiro



Precision in 2D temperature measurements using the thermographic phosphor BAM  

NASA Astrophysics Data System (ADS)

Investigation of optimized spatial precision for surface temperature measurements is performed. The temperature is measured by means of two-color ratio imaging with ICCD cameras, using the thermographic phosphor BAM. The precision in temperature is put in relation to the spatial resolution, two quantities which involve a trade-off in this case: the more spatial smoothing the better precision, but also the worse spatial resolution. Two different setups are used in order to investigate the influence of laser shot-to-shot variations, the flat-field correction and image registration process on the precision. In order to achieve high precision it is crucial to operate the ICCD cameras with a gain setting that does not introduce nonlinearity effects at the present level of irradiance. The results provide guidance on the precision to be expected from surface temperature measurements using the two-color ratio technique in combination with thermographic phosphors and also confirm the importance of highly stable and linear ICCD detectors. At room temperature and low spatial resolution the precision is evaluated to 0.4%.

Lindén, J.; Knappe, C.; Richter, M.; Aldén, M.



High-resolution GPR imaging using a nonstandard 2D EEMD technique  

NASA Astrophysics Data System (ADS)

Ground Penetrating Radar (GPR) data are affected by a variety of factors. Linear and nonlinear data processing methods each have been widely applied to the GPR use in geophysical and engineering investigations. For complicated data such as the shallow earth image of urban area, a better result can be achieved by integrating both approaches. In this study, we introduce a nonstandard 2D EEMD approach, which integrates the natural logarithm transformed (NLT) ensemble empirical mode decomposition (EEMD) method with the linear filtering technique to process GPR images. The NLT converts the data into logarithmic values; therefore, it permits a wide dynamic range for the recorded GPR data to be presented. The EEMD dyadic filter bank decomposes the data into multiple components ready for image reconstruction. Consequently, the NLT EEMD method provides a new way of nonlinear energy compensating and noise filtering with results having minimal artifacts. However, horizontal noise in the GPR time-distance section may be enhanced after NLT process in some cases. To solve the dilemma, we process the data two dimensionally. At first, the vertical background noise of each GPR trace is removed by using a standard linear method, the background noise removal algorithm, or simply by performing the sliding background removal filter. After that, the NLT is applied to the data for examining the horizontal coherent energy. Next, we employ the EEMD filter bank horizontally at each time step to remove the horizontal coherent energy. After removing the vertical background noise and horizontal coherent energy, a vertical EEMD method is then applied to generate a filter bank of the GPR time-distance section for final image reconstruction. Two buried models imitating common shallow earth targets are used to verify the effectiveness of the proposed scheme. One model is a brick cistern buried in a disturbed site of poor reflection quality. The other model is a buried two-stack metallic target that the signal reflected from the lower stack is often masked by the upper one. Compared with the results obtained by using standard processing methods, the proposed approach significantly improves the target resolution. A field example is also provided to demonstrate the competence of the proposed scheme. Keywords: GPR; 2D EEMD; Logarithmic transform; Horizontal coherent energy

Chen, Chih-Sung; Jeng*, Yih; Yu, Hung-Ming



Temperature and layer number dependence of the G and 2D phonon energy and damping in graphene.  


We have studied the temperature and size dependence of the G and 2D phonon modes in graphene. It is shown that in a graphene monolayer the phonon energy decreases whereas the phonon damping increases with increasing temperature. The electron-phonon interaction leads to hardening whereas the fourth-order anharmonic phonon-phonon processes lead to softening of the phonon energy with increasing temperature. We have shown that the electron-phonon interaction plays an important role also by the dispersion dependence of the phonon G mode, by the observation of the Kohn anomaly. The G mode frequency decreases and damping increases, whereas the 2D phonon frequency and damping increase with increasing layer number. The temperature and size effects of the 2D mode are much stronger than those of the G mode. PMID:22569003

Apostolov, A T; Apostolova, I N; Wesselinowa, J M



Novel Ultrasound Images Shot Noise Removal Algorithm Based On 2-D Wavelet Decomposition and Stable Distribution Model  

Microsoft Academic Search

Ultrasonic images are generally affected by multiplicative shot noise. This paper analyzes and models the coefficients of 2-D multiresolution wavelet decomposition of logarithmically transformed images using alpha stable distribution. We propose a new function that performs a nonlinear operation on the data of classifying the coefficients, thus get a new noise-removal method based on multiresolution wavelet decomposition and alpha stable

Daifeng Zha



Concurrent Measurement of 2-D Temperature Distributions and Radiative Properties of Pulverized-coal-fired Flame in a 670 t/h Boiler Furnace  

NASA Astrophysics Data System (ADS)

Both temperature distributions and radiative properties play important roles in boilers and furnaces. Based on radiative imaging models, the 2-D temperature distribution and radiative properties can be simultaneously reconstructed from the boundary radiative information detected by image detectors. In this paper, the 2-D temperature distributions and radiative properties of pulverized-coal-fired flame in three typical cross-sections of a 670 t/h boiler furnace were measured. At the same time, the particles in the three cross-sections of the furnace were sampled and then, the chemical compositions, shapes and size distributions of the particles were given. The experimental results showed that the measured 2-D temperature can be used in combustion diagnosis, and the radiative properties in the burner area of the furnace are larger than those in the outlet of the boiler furnace. The value of measured radiatvie properties is proportional with the carbon content in sampled particles. The radiative properties of smooth ash are smaller while those of porous char are larger.

Lou, Chun; Zhou, Huai-Chun



Comparison of 2D, 3D high dose and 3D low dose gated myocardial 82Rb PET imaging  

PubMed Central

Background We compared 2D, 3D high dose (HD) and 3D low dose (LD) gated myocardial Rb-82 PET imaging in 16 normal human studies. The main goal in the paper is to evaluate whether the images obtained by a 3D LD studies are still of comparable clinical quality to the images obtained with the 2D HD or 3D HD studies. Methods All 2D and 3D HD studies were performed with 2220 MBq of Rb-82. The 3D LD were performed with 740 MBq of Rb-82. A GE Advance PET system was used for acquisition. Polar maps were created and used to calculate noise among (NAS) and within (NWS) the segments in the noise analysis. In addition, the contrast between left ventricular (LV) wall and LV cavity was also analysed. For 13 subjects, ejection fraction (EF) on 2D and 3D studies was calculated using QGS program. Results For the H20 reconstruction filter, the mean contrast in mid-ventricular short-axis slice was 0.33 ± 0.06 for 2D studies. The same contrast for the 3D HD studies was 0.38 ± 0.07 and for 3D LD, it was 0.34 ± 0.08. For the 6 volunteers where 3D HD was used, NAS was 3.64*10-4 and NWS was 1.79*10-2 for 2D studies, and NAS was 3.70*10-4 and NWS was 1.85*10-2 for 3D HD studies, respectively. For the other 10 volunteers where 3D LD was used, NAS was 3.85*10-4 and NWS was 1.82*10-2 for the 2D studies, and NAS was 5.58*10-4 and NWS was 1.91*10-2 for the 3D LD studies, respectively. For the sharper H13 filter, the data followed the same pattern, with slightly higher values of contrast and noise. EF values in 2D and 3D were close. The Pearson's correlation coefficient was 0.90. The average difference from 13 subjects was 8.3%. Conclusion 2D and 3D HD gating Rb-82 PET cardiac studies have similar contrast, ejection fractions and noise levels. 3D LD gating imaging, gave comparable results in terms of contrast, EF and noise to either 2D or 3D HD gating PET imaging. 3D LD PET gated imaging can make Rb-82 PET cardiac imaging more affordable with significantly less radiation exposure to the patients.

Knesaurek, Karin; Machac, Josef; Ho Kim, Jong



Coronary arteries motion modeling on 2D x-ray images  

NASA Astrophysics Data System (ADS)

During interventional procedures, 3D imaging modalities like CT and MRI are not commonly used due to interference with the surgery and radiation exposure concerns. Therefore, real-time information is usually limited and building models of cardiac motion are difficult. In such case, vessel motion modeling based on 2-D angiography images become indispensable. Due to issues with existing vessel segmentation algorithms and the lack of contrast in occluded vessels, manual segmentation of certain branches is usually necessary. In addition, such occluded branches are the most important vessels during coronary interventions and obtaining motion models for these can greatly help in reducing the procedure time and radiation exposure. Segmenting different cardiac phases independently does not guarantee temporal consistency and is not efficient for occluded branches required manual segmentation. In this paper, we propose a coronary motion modeling system which extracts the coronary tree for every cardiac phase, maintaining the segmentation by tracking the coronary tree during the cardiac cycle. It is able to map every frame to the specific cardiac phase, thereby inferring the shape information of the coronary arteries using the model corresponding to its phase. Our experiments show that our motion modeling system can achieve promising results with real-time performance.

Gao, Yang; Sundar, Hari



2D-sensitive hpxe gas proportional scintillation counter concept for nuclear medical imaging purposes  

NASA Astrophysics Data System (ADS)

The operation and first images of a high pressure xenon Gas Proportional Scintillation Counter (GPSC) are presented. In this setup, primary electrons produced by the absorption of X- or ?-rays in the gas medium drift to a region where the electric field is set to a value above the gas scintillation threshold, the scintillation region. The primary ionization signal is amplified through the electroluminescence produced along the electron drift in this region. A Micro-Hole and Strip Plate covered with CsI (CsI-MHSP) is used as the photosensor for the scintillation readout. The 2D capability of the CsI-MHSP photosensor is achieved by means of two orthogonal resistive lines interconnecting the strips patterned on both surfaces of the MHSP. The interaction position of the incident radiation can be obtained by determining the centroid of the photosensor area irradiated by the electroluminescence pulse. This centroid is obtained from the amplitude of the charge pulses collected at both ends of the resistive lines. Preliminary analyses of the first images obtained with electroluminescence signals at xenon pressures up to 3 bar indicate a position resolution capability of about 1.2 mm at 2.9 bar, for 59.6 keV ?-photons.

Azevedo, C. D. R.; Silva, A. L. M.; Ferreira, A. L.; Natal da Luz, H.; Moutinho, L. M.; dos Santos, J. M. F.; Veloso, J. F. C. A.



Hyper-spectral confocal nano-imaging with a 2D super-lens.  


Achieving sub-100 nm resolution over a broad visible bandwidth has long been an elusive goal in the nano-imaging of cell-surface interfaces. While metamaterial super-lenses and near-field optics have been previously demonstrated, these techniques can operate only at one wavelength, and do not provide accesses to the cell-surface interfaces. Here, we investigate a broadband 2D lens comprised of an oblate spheroidal dielectric cavity embedded just beneath a planar metal surface. The lens operates by adiabatically focusing asymmetric plasmon energies at sub-100 nm scale on the low-index side of the thin metal film formed between the cavity top and the planar metal surface. We then proposed the use of our lens in a high-resolution far-field confocal microscopy setup. Due to the surface-field nature of our lens, the presented system holds potential as an indispensable tool for cell-surface interfacial studies that require sub-100 nm hyper-spectral imaging analysis. PMID:21369070

Kho, Kiang Wei; Zexiang, Shen; Malini, Olivo



About the role of 2D screening in high temperature superconductivity  

NASA Astrophysics Data System (ADS)

The 2D screening is investigated in a simple single band square tight-binding model which qualitatively resembles the known electronic structure in high temperature superconductors. The Coulomb kernel for the two particle Bethe Salpeter equation in the single loop (RPA) approximation for the polarization can be evaluated in a strong tight-binding limit. The results indicate an intense screening of the Coulomb repulsion between the particles, which becomes stronger and anisotropic when the Fermi level approaches half filling (or, equivalently, when the Fermi surface turns to be near the Van Hove singularities) and rapidly decreases away from it. The effect is also more pronounced for quasi-momenta regions near the corners of the Brillouin cell, which corresponds to dual spatial distances of the order of a few unit cells. Therefore, a possible mechanism is identified which could explain the existence of extremely small Cooper pairs in these materials, as bounded anisotropic composite particles joined by residual super-exchange or phonon interactions.

Vazquez-Ponce, Yosdanis; Aguero, David Oliva; Cabo Montes de Oca, Alejandro



Angle-independent strain mapping in myocardial elastography 2D strain tensor characterization and principal component imaging  

Microsoft Academic Search

A current limitation of the implementation of myocardial elastography in a clinical setting is the difficulty of interpreting the one-dimensional strain maps due to varying strain values in the wall of the left ventricle (LV). In this paper, we demonstrate a robust angle-independent method for 2D myocardial elastography on simulated 2D ultrasonic images of a 3D finite-element analysis (FEA) model

S. D. Fung-Kee-Fung; W.-N. Lee; C. M. Ingrassia; K. D. Costa; E. E. Konofagou



Friction-induced dynamic chemical changes of tricresyl phosphate as lubricant additive observed under boundary lubrication with 2D fast imaging FTIR-ATR spectrometer  

Microsoft Academic Search

The chemical reaction of tricresyl phosphate (TCP) during friction motion has been investigated by using our newly developed in situ observation system of the two-dimensional fast imaging FTIR-ATR spectrometer combined with the temperature-controlled friction equipment (Sasaki et al. (2008) [18]). The time-dependent 2D distribution of chemical reaction on the friction surface was obtained for the first time. By using the

Keiji Sasaki; Naruhiko Inayoshi; Kohji Tashiro



640 x 400 pixels a-Si:H TFT-driven 2D image sensor  

NASA Astrophysics Data System (ADS)

A 640 X 400 pixels and 64 dots/mm2 2-dimensional (2-D) contact image sensor has been fabricated by integrating amorphous silicon (a-Si:H) photodiodes (PDs) and thin film transistors (TFTs). The sensor consists of 400 gate and 640 signal lines, and thus contains 256,000 pixels. The PD has a Cr/n-i-p a-Si:H/ITO structure. The TFT has an inverted staggered structure and Ta/TaMo is used for a gate electrode in order to suppress a gate pulse delay. When the TFTs of the n-th row are turned on, photo-generated charges stored in the PD capacitances in the n-th row are transferred to their respective signal line capacitances. After that, the charges are detected by an external voltage sensitive amplifier. The 640 parallel outputs are converted to the serial analog signal by a multiplexer for image processing. The sensor has achieved photoresponsivity of 7.2 V/lx-s, photoresponsivity non-uniformity of +/- 8% and the signal-to-noise (S/N) ratio of 50 dB at the operation of 30 ms/frame scanning speed. Crosstalk as the influence of adjacent lines both X and Y direction is less than 1.3%. This value is estimated to enable achievement of more than 64 levels of gray. The reproduced image quality regarding resolution was good for 8-point kanji characters. This technology will be applicable for multifunctional input/output device mounted on a system such as a pen computer and X-ray detector coupled to a scintillator.

Kobayashi, Kenichi; Makida, Seigo; Sato, Yoshihide; Hamano, Toshihisa



Stochastic rank correlation: A robust merit function for 2D/3D registration of image data obtained at different energies  

PubMed Central

In this article, the authors evaluate a merit function for 2D/3D registration called stochastic rank correlation (SRC). SRC is characterized by the fact that differences in image intensity do not influence the registration result; it therefore combines the numerical advantages of cross correlation (CC)-type merit functions with the flexibility of mutual-information-type merit functions. The basic idea is that registration is achieved on a random subset of the image, which allows for an efficient computation of Spearman’s rank correlation coefficient. This measure is, by nature, invariant to monotonic intensity transforms in the images under comparison, which renders it an ideal solution for intramodal images acquired at different energy levels as encountered in intrafractional kV imaging in image-guided radiotherapy. Initial evaluation was undertaken using a 2D/3D registration reference image dataset of a cadaver spine. Even with no radiometric calibration, SRC shows a significant improvement in robustness and stability compared to CC. Pattern intensity, another merit function that was evaluated for comparison, gave rather poor results due to its limited convergence range. The time required for SRC with 5% image content compares well to the other merit functions; increasing the image content does not significantly influence the algorithm accuracy. The authors conclude that SRC is a promising measure for 2D/3D registration in IGRT and image-guided therapy in general.

Birkfellner, Wolfgang; Stock, Markus; Figl, Michael; Gendrin, Christelle; Hummel, Johann; Dong, Shuo; Kettenbach, Joachim; Georg, Dietmar; Bergmann, Helmar



Robust lumen segmentation of coronary arteries in 2D angiographic images  

NASA Astrophysics Data System (ADS)

Diagnosis and treatment of coronary diseases depends on the data acquired during angiographic investigations. To provide better assistance for angiographic procedures, a segmentation of the lumen is required. A new algorithm for vessel centerline computation and lumen segmentation in 2D projection coronary angiograms is presented. Centerlines are extracted by a graph-based optimization technique, which searches for paths with minimal costs. The search starts from a source point, which is automatically set by the proposed algorithm. A new objective function for determining the costs of the graph edges is proposed. It consists of the response from the medialness filter and is regularized by the centerline potential function. In the medialness filter a vessel cross-section is represented by a 1D profile parameterized by center position and radius. The medialness filter at a point optimizes a gradient-based response over the profile radius. The proposed centerline potential function defines likeliness of each point of the image to be a centerline. Both the medialness filter and the centerline potential function are multi-scale. The entire lumen segmentation is achieved by the radii extracted during the medialness response computation. Application to clinical data shows that the presented algorithm segments coronary lumen with good accuracy and allows for subsequent assessment of the quantitative characteristics (i.e. diameter, curvature, etc.) of the vessels.

Polyanskaya, Maria; Schwemmer, Chris; Linarth, Andre; Lauritsch, Guenter; Hornegger, Joachim



Estimating Microtubule Distributions from 2D Immunofluorescence Microscopy Images Reveals Differences among Human Cultured Cell Lines  

PubMed Central

Microtubules are filamentous structures that are involved in several important cellular processes, including cell division, cellular structure and mechanics, and intracellular transportation. Little is known about potential differences in microtubule distributions within and across cell lines. Here we describe a method to estimate information pertaining to 3D microtubule distributions from 2D fluorescence images. Our method allows for quantitative comparisons of microtubule distribution parameters (number of microtubules, mean length) between different cell lines. Among eleven cell lines compared, some showed differences that could be accounted for by differences in the total amount of tubulin per cell while others showed statistically significant differences in the balance between number and length of microtubules. We also observed that some cell lines that visually appear different in their microtubule distributions are quite similar when the model parameters are considered. The method is expected to be generally useful for comparing microtubule distributions between cell lines and for a given cell line after various perturbations. The results are also expected to enable analysis of the differences in gene expression underlying the observed differences in microtubule distributions among cell types.

Wiking, Mikaela; Lundberg, Emma; Rohde, Gustavo K.; Murphy, Robert F.



Growth of Protein 2-D Crystals on Supported Planar Lipid Bilayers Imaged in Situby AFM  

Microsoft Academic Search

Theories of crystallization, both in 3-D and 2-D, are still very limited, mainly due to the scarcity of experimental approaches providing pertinent data on elementary phenomena. We present here a novel experimental approach for following, in real time andin situ, the process of 2-D crystallization of proteins on solid supports. Using annexin V as a model of a protein binding

Ilya Reviakine; Wilma Bergsma-Schutter; Alain Brisson



Spectroscopic-tomography of biological membrane with high-spatial resolution by the imaging-type 2D Fourier spectroscopy  

NASA Astrophysics Data System (ADS)

We proposed the imaging-type 2-dimensional Fourier spectroscopy that is the phase-shift interferometry between the objective lights. The proposed method can measure the 2D spectral image at the limited depth. Because of the imaging optical system, the 2D spectral images can be measured in high spatial resolution. And in the depth direction, we can get the spectral distribution only in the focal plane. In this report, we mention about the principle of the proposed wide field imaging-type 2D Fourier spectroscopy. And, we obtained the spectroscopic tomography of biological tissue of mouse's ear. In the visible region, we confirmed the difference of spectral characteristics between blood vessel region and other region. In the near infrared region (?=900nm~1700nm), we can obtain the high-contrast blood vessel image of mouse's ear in the deeper part by InGaAs camera. Furthermore, in the middle infrared region(?=8?~14?m), we have successfully measured the radiation spectroscopic-imaging with wild field of view by the infrared module, such as the house plants. Additionally, we propose correction geometrical model that can convert the mechanical phase-shift value into the substantial phase difference in each oblique optical axes. We successfully verified the effectiveness of the proposed correction geometrical model and can reduce the spectral error into the error range into +/-3nm using the He-Ne laser whose wavelength 632.8nm.

Inui, Asuka; Tsutsumi, Ryosuke; Qi, Wei; Takuma, Takashi; Ishimaru, Ichiro



Temperature Dependence of the Josephson Current in the d Wave Superconductor Junction Based on the 2-D Extended Hubbard Model  

Microsoft Academic Search

We present a theoretical study of the Josephson current in the dx2-y2-wave superconductor junction. We calculate the current-phase relation and the temperature dependence of the Josephson current for the (100) oriented and the (110) oriented junction using the two-dimensional (2-D) extended Hubbard model. We obtain the anomalous temperature dependence of the current in the (110) oriented junction which has been

S. Shirai; H. Tsuchiura; Y. Tanaka; J. Inoue; S. Kashiwaya



A Statistical Method for Analysis of Technical Data of a Badminton Match Based on 2-D Seriate Images  

Microsoft Academic Search

The use of computer vision technology to collect and analyze statistics during badminton matches or training sessions can be expected to provide valuable information to help coaches to determine which tactics should be used by a player in a given game or to improve the player's tactical training. A method based on 2-D seriate images by which statistical data of

Bingqi Chen; Zhiqiang Wang



Demonstration of an Ultra-fast Encryption for an OTDM\\/WDM Signal Expressed as a 2D Image  

Microsoft Academic Search

We demonstrate an ultra-fast encryption for an OTDM\\/WDM signal expressed as a 2D image. Data are scrambled by a temporal shuffle. Experimental results show the basic function of the proposed encryption system. The system throughput is estimated at the bit rate of equivalent 3 Tbps.

Ryosuke Itoh; Tsuyoshi Konishi; Kazuyoshi Itoh



Evaluation of Intensity-Based 2D-3D Spine Image Registration Using Clinical Gold-Standard Data  

Microsoft Academic Search

In this paper, we evaluate the accuracy and robustness of intensity-based 2D-3D registration for six image similarity measures us- ing clinical gold-standard spine image data from four patients. The gold- standard transformations are obtained using four bone-implanted fidu- cial markers. The three best similarity measures are mutual information, cross correlation, and gradient correlation. The mean target registration errors for these

Daniel B. Russakoff; Torsten Rohlfing; Anthony Ho; Daniel H. Kim; Ramin Shahidi; John R. Adler Jr.; Calvin R. Maurer Jr.



Full-field Thermal Deformation Measurements in a Scanning Electron Microscope by 2D Digital Image Correlation  

Microsoft Academic Search

Using recently developed methods for application of a nano-scale random pattern having high contrast during SEM imaging, baseline\\u000a full-field thermal deformation experiments have been performed successfully in an FEI Quanta SEM using 2D-DIC methods. Employing\\u000a a specially redesigned commercial heating plate and control system, with modified specimen attachment procedures to minimize\\u000a unwanted image motions, recently developed distortion correction procedures were

N. Li; M. A. Sutton; X. Li; H. W. Schreier



Fast non-blind deconvolution based on 2D point spread function database for real-time ultrasound imaging  

NASA Astrophysics Data System (ADS)

In the ultrasound medical imaging system, blurring which occurs after passing through ultrasound scanner system, represents Point Spread Function (PSF) that describes the response of the ultrasound imaging system to a point source distribution. So, de-blurring can be achieved by de-convolving the images with an estimated of PSF. However, it is hard to attain an accurate estimation of PSF due to the unknown properties of the tissues of the human body through the ultrasound signal propagates. In addition to, the complexity is very high in order to estimate point spread function and de-convolve the ultrasound image with estimated PSF for real-time implementation of ultrasound imaging. Therefore, conventional methods of ultrasound image restoration are based on a simple 1D PSF estimation [8] that axial direction only by restoring the performance improvement is not in the direction of Lateral. And, in case of 2D PSF estimation, PSF estimation and restoration of the high complexity is not being widely used. In this paper, we proposed new method for selection of the 2D PSF (estimated PSF of the average speed sound and depth) simultaneously with performing fast non-blind 2D de-convolution in the ultrasound imaging system. Our algorithm works on the beam-formed uncompressed radio-frequency data, with pre-measured and estimated 2D PSFs database from actual probe used. In the 2d PSF database, there are pre-measured and estimated 2D PSFs that classified the each different depth (about 5 different depths) and speed of sound (about 1450 or 1540m/s). Using a minimum variance and simple Weiner filter method, we present a novel way to select the optimal 2D PSF in pre-measured and estimated 2D PSFs database that acquired from the actual transducer being used. For de-convolution part with the chosen PSF, we focused on the low complexity issue. So, we are using the Weiner Filter and fast de-convolution technique using hyper-Laplacian priors [11], [12] which is several orders of magnitude faster than existing techniques that use hyper-Laplacian priors. Then, in order to prevent discontinuities between the differently restored each depth image regions, we use the piecewise linear interpolation on overlapping regions. We have tested our algorithm with vera-sonic system and commercial ultrasound scanner (Philips C4-2), in known speed of sound phantoms and unknown speeds in vivo scans. We have applied a non-blind de-convolution with 2D PSFs database for ultrasound imaging system. Using the real PSF from actual transducer being used, our algorithm produces a better restoration of ultrasound image than de-convolution by simulated PSF, and has low complexity for real-time ultrasound imaging. This method is robust and easy to implement. This method may be a realistic candidate for real-time implementation.

Kang, Jooyoung; Park, Sung-Chan; Kim, Kyuhong; Kim, Jung-Ho



Towards real-time 2D/3D registration for organ motion monitoring in image-guided radiation therapy  

NASA Astrophysics Data System (ADS)

Nowadays, radiation therapy systems incorporate kV imaging units which allow for the real-time acquisition of intra-fractional X-ray images of the patient with high details and contrast. An application of this technology is tumor motion monitoring during irradiation. For tumor tracking, implanted markers or position sensors are used which requires an intervention. 2D/3D intensity based registration is an alternative, non-invasive method but the procedure must be accelerate to the update rate of the device, which lies in the range of 5 Hz. In this paper we investigate fast CT to a single kV X-ray 2D/3D image registration using a new porcine reference phantom with seven implanted fiducial markers. Several parameters influencing the speed and accuracy of the registrations are investigated. First, four intensity based merit functions, namely Cross-Correlation, Rank Correlation, Mutual Information and Correlation Ratio, are compared. Secondly, wobbled splatting and ray casting rendering techniques are implemented on the GPU and the influence of each algorithm on the performance of 2D/3D registration is evaluated. Rendering times for a single DRR of 20 ms were achieved. Different thresholds of the CT volume were also examined for rendering to find the setting that achieves the best possible correspondence with the X-ray images. Fast registrations below 4 s became possible with an inplane accuracy down to 0.8 mm.

Gendrin, C.; Spoerk, J.; Bloch, C.; Pawiro, S. A.; Weber, C.; Figl, M.; Markelj, P.; Pernus, F.; Georg, D.; Bergmann, H.; Birkfellner, W.



Non-equilibrium partitioning tracer transport in porous media: 2-D physical modelling and imaging using a partitioning fluorescent dye  

Microsoft Academic Search

This paper describes an investigation into non-equilibrium partitioning tracer transport and interaction with non-aqueous-phase liquid (NAPL) contaminated water-saturated porous media using a two-dimensional (2-D) physical modelling methodology. A fluorescent partitioning tracer is employed within a transparent porous model which when imaged by a CCD digital camera can provide full spatial tracer concentrations and tracer breakthrough curves. Quasi one-dimensional (1-D) benchmarking

Edward H. Jones; Colin C. Smith



Interobserver, Intraobserver and Intrapatient Reliability Scores of Myocardial Strain Imaging with 2-D Echocardiography in Patients Treated with Anthracyclines  

Microsoft Academic Search

Myocardial strain imaging with 2-D echocardiography is a relatively new noninvasive method to assess myocardial deformation. To determine the interobserver, intraobserver and intrapatient reliability scores, we evaluated myocardial strain measurements of 10 asymptomatic survivors of childhood cancer. Ten patients were selected randomly out of a follow-up cohort of childhood cancer survivors. All 10 patients underwent a transthoracic echocardiographic examination. Two-dimensional

Annelies M. C. Mavinkurve-Groothuis; Gert Weijers; Jacqueline Groot-Loonen; Milanthy Pourier; Ton Feuth; Chris L. de Korte; Peter M. Hoogerbrugge; Livia Kapusta



Using artificial neural networks to invert 2D DC resistivity imaging data for high resistivity contrast regions: A MATLAB application  

Microsoft Academic Search

MATLAB is a high-level matrix\\/array language with control flow statements and functions. MATLAB has several useful toolboxes to solve complex problems in various fields of science, such as geophysics. In geophysics, the inversion of 2D DC resistivity imaging data is complex due to its non-linearity, especially for high resistivity contrast regions. In this paper, we investigate the applicability of MATLAB

Ahmad Neyamadpour; Samsudin Taib; W. A. T. Wan Abdullah



Comparison of 2D temperature maps recorded during laser-induced thermal tissue treatment with corresponding temperature distributions calculated from 3D Monte-Carlo simulations  

Microsoft Academic Search

Minimally invasive techniques often require special biomedical monitoring schemes. In the case of laser coagulation of tumors accurate temperature mapping is desirable for therapy control. While magnetic resonance (MR)-based thermometry can easily yield qualitative results it is still difficult to calibrate this technique with independent temperature probes for the entire 2D field of view. Calculated temperature maps derived from Monte-Carlo

Harald Busse; Martin Bublat; Ralf Ratering; Margarethe Rassek; Hans-Joachim Schwarzmaier; Thomas Kahn



Estimation of the Lateral Ventricles Volumes from a 2D Image and Its Relationship with Cerebrospinal Fluid Flow  

PubMed Central

Purpose. This work suggests a fast estimation method of the lateral ventricles volume from a 2D image and then determines if this volume is correlated with the cerebrospinal fluid flow at the aqueductal and cerebral levels in neurodegenerative diseases. Materials and Methods. FForty-five elderly patients suffering from Alzheimer's disease (19), normal pressure hydrocephalus (13), and vascular dementia (13) were involved and underwent anatomical and phase contrast MRI scans. Lateral ventricles and stroke volumes were assessed on anatomical and phase contrast scans, respectively. A common reference plane was used to calculate the lateral ventricles' area on 2D images. Results. The largest volumes were observed in hydrocephalus patients. The linear regression between volumes and areas was computed, and a strong positive correlation was detected (R2 = 0.9). A derived equation was determined to represent the volumes for any given area. On the other hand, no significant correlations were detected between ventricles and stroke volumes (R2 ? 0.15). Conclusion. Lateral ventricles volumes are significantly proportional to the 2D reference section area and could be used for patients' follow-up even if 3D images are unavailable. The cerebrospinal fluid fluctuations in brain disorders may depend on many physiological parameters other than the ventricular morphology.

Bader, Chaarani; Cyrille, Capel; Jadwiga, Zmudka; Joel, Daouk; Fichten, Anthony; Catherine, Gondry-Jouet; Roger, Bouzerar; Olivier, Baledent



Study on the imaging ability of the 2D neutron detector based on MWPC  

NASA Astrophysics Data System (ADS)

A 2D neutron detector based on 3He convertor and MWPC with an active area of 200 mm×200 mm has been successfully designed and fabricated. The detector has been tested with Am/Be neutron source and with collimated neutron beam with the wavelength of ?=1.37 Å. The best spatial resolution of 1.18 mm (FWHM) and good linearity were obtained. This is in good agreement with theoretical calculations.

Tian, LiChao; Chen, YuanBo; Tang, Bin; Zhou, JianRong; Qi, HuiRong; Liu, RongGuang; Zhang, Jian; Yang, GuiAn; Xu, Hong; Chen, DongFeng; Sun, ZhiJia



A modified image encryption scheme based on 2D chaotic map  

Microsoft Academic Search

In this paper, we proposed a modified chaotic based image encryption scheme using two logistic maps and two-dimensional baker map. In encryption process pixel, integration of diffusion and chaotic confusion are adopted. For pixel diffusion, we employed two-dimensional baker map to shuffle the positions of image pixels which can diffuse the relationship between the cipher-image and plain-image. Further, XOR operation

Rashidah Kadir; Rosdiana Shahril; Mohd Aizaini Maarof



A comparison of 2D and 3D evaluation methods for pulmonary embolism detection in CT images  

NASA Astrophysics Data System (ADS)

Pulmonary embolism (PE) is a life-threatening disease, requiring rapid diagnosis and treatment. Contrast enhanced computed tomographic (CT) images of the lungs allow physicians to confirm or rule out PE, but the large number of images per study and the complexity of lung anatomy may cause some emboli to be overlooked. We evaluated a novel three-dimensional (3D) visualization technique for detecting PE, and compared it with traditional 2D axial interpretation. Three readers independently marked 10 cases using the 3D method, and a separate interpretation was performed at a later date using only source axial images. An experienced thoracic radiologist adjudicated all marks, classifying clots according to location and confidence. There were a total of 8 positive examinations with 69 validated emboli. 44 (64%) of the clots were segmental while 12 (17%) proved subsegmental. Using the traditional 2D method for examination, readers detected a mean of 45 PE for 66% sensitivity. Using the 3D method, readers detected a mean of 35 PE (50% sensitivity). Combining both methods, readers detected a mean of 51 PE (74% sensitivity), significantly higher than either single method (p<0.001). Considered by arterial level, significant improvement was observed for detection of segmental and subsegmental clots (p<0.001) when comparing combined reading with either single method. The mean number of false positives per patient was 0.23 for both 2D and 3D readings and 0.4 for combined reading. 3D visualization of pulmonary arteries allowed readers to detect a significant number of additional emboli not detected during 2D axial interpretations and thus may lead to a more accurate diagnosis of PE.

Kiraly, Atilla P.; Novak, Carol L.; Naidich, David P.; Vlahos, Ioannis; Ko, Jane P.; Brusca-Augello, Geraldine T.



Object tracking in medical imaging using a 2D active mesh system  

Microsoft Academic Search

This article proposes a technique for tracking moving organs in medical imaging. It can be split into two stages. We first initialize a 1D-triangular mesh on the first image of the sequence. We distinguish different objects of interest by grouping together the triangles that make them up. Afterwards, we deform this mesh on the successive images in order to track

J. Lautissier; L. Legrand; A. Lalande; P. Walker; F. Brunotte



Combined 3D photoacoustic and 2D fluorescence imaging of indocyanine green contrast agent flow  

NASA Astrophysics Data System (ADS)

Photoacoustic imaging uses laser induced ultrasound transients to generate optical absorption maps of the illuminated volume. In this work, we used a custom built photoacoustic imaging system consisting of a 60-channel transducer array, a 50 MHz data acquisition system, and an Nd:YAG pumped OPO laser, to perform simultaneous photoacoustic and fluorescence imaging. A single 780 nm laser pulse generated both ultrasound and fluorescence, enabling reconstruction of images for both modalities with near perfect temporal co-registration. The result highlighted the ability of photoacoustic imaging to supplement fluorescence data when optical scatter reduces fluorescence resolution beyond its useful range.

Kosik, Ivan; Carson, Jeffrey J. L.



Curve-based 2D-3D registration of coronary vessels for image guided procedure  

NASA Astrophysics Data System (ADS)

3D roadmap provided by pre-operative volumetric data that is aligned with fluoroscopy helps visualization and navigation in Interventional Cardiology (IC), especially when contrast agent-injection used to highlight coronary vessels cannot be systematically used during the whole procedure, or when there is low visibility in fluoroscopy for partially or totally occluded vessels. The main contribution of this work is to register pre-operative volumetric data with intraoperative fluoroscopy for specific vessel(s) occurring during the procedure, even without contrast agent injection, to provide a useful 3D roadmap. In addition, this study incorporates automatic ECG gating for cardiac motion. Respiratory motion is identified by rigid body registration of the vessels. The coronary vessels are first segmented from a multislice computed tomography (MSCT) volume and correspondent vessel segments are identified on a single gated 2D fluoroscopic frame. Registration can be explicitly constrained using one or multiple branches of a contrast-enhanced vessel tree or the outline of guide wire used to navigate during the procedure. Finally, the alignment problem is solved by Iterative Closest Point (ICP) algorithm. To be computationally efficient, a distance transform is computed from the 2D identification of each vessel such that distance is zero on the centerline of the vessel and increases away from the centerline. Quantitative results were obtained by comparing the registration of random poses and a ground truth alignment for 5 datasets. We conclude that the proposed method is promising for accurate 2D-3D registration, even for difficult cases of occluded vessel without injection of contrast agent.

Duong, Luc; Liao, Rui; Sundar, Hari; Tailhades, Benoit; Meyer, Andreas; Xu, Chenyang



A Detector for 2-D Neutron Imaging for the Spallation Neutron Source  

SciTech Connect

Abstract - We have designed, built, and tested a 2-D pixellated thermal neutron detector. The detector is modeled after the MicroMegas-type structure previously published for collider-type experiments. The detector consists of a 4X4 square array of 1 cm 2 pixels each of which is connected to an individual preamplifier-shaper-data acquisition system. The neutron converter is a 10B film on an aluminum substrate. We describe the construction of the detector and the test results utilizing 252Cf sources in Lucite to thermalize the neutrons.Drift electrode (Aluminum) Converter (10B) 3 mm Conversion gap neutron (-900 V)

Britton Jr, Charles L [ORNL; Bryan, W. L. [Oak Ridge National Laboratory (ORNL); Wintenberg, Alan Lee [ORNL; Clonts, Lloyd G [ORNL; Warmack, Robert J Bruce [ORNL; McKnight, Timothy E [ORNL; Frank, Steven Shane [ORNL; Cooper, Ronald G [ORNL; Dudney, Nancy J [ORNL; Veith, Gabriel M [ORNL



Full 2D displacement vector and strain tensor estimation for superficial tissue using beam-steered ultrasound imaging.  


Ultrasound strain imaging is used to measure local tissue deformations. Usually, only strains along the ultrasound beam are estimated, because those estimates are most precise, due to the availability of phase information. For estimating strain in other directions we propose to steer the ultrasound beam at an angle, which allows estimating different projections of the 2D strain tensor, while phase information remains available. This study investigates beam steering at maximally three different angles to determine the full 2D strain tensor. The method was tested on simulated and experimental data of an inclusion phantom and a vessel phantom. The combination of data from a non-steered acquisition and acquisitions at a large positive and an equally large but negative steering angle enabled the most precise estimation of the strain components. The method outperforms conventional methods that do not use beam steering. PMID:20479516

Hansen, H H G; Lopata, R G P; Idzenga, T; de Korte, C L



Analysis of image heterogeneity using 2D Minkowski functionals detects tumor responses to treatment.  


PURPOSE: The acquisition of ever increasing volumes of high resolution magnetic resonance imaging (MRI) data has created an urgent need to develop automated and objective image analysis algorithms that can assist in determining tumor margins, diagnosing tumor stage, and detecting treatment response. METHODS: We have shown previously that Minkowski functionals, which are precise morphological and structural descriptors of image heterogeneity, can be used to enhance the detection, in T(1) -weighted images, of a targeted Gd(3+) -chelate-based contrast agent for detecting tumor cell death. We have used Minkowski functionals here to characterize heterogeneity in T(2) -weighted images acquired before and after drug treatment, and obtained without contrast agent administration. RESULTS: We show that Minkowski functionals can be used to characterize the changes in image heterogeneity that accompany treatment of tumors with a vascular disrupting agent, combretastatin A4-phosphate, and with a cytotoxic drug, etoposide. CONCLUSIONS: Parameterizing changes in the heterogeneity of T(2) -weighted images can be used to detect early responses of tumors to drug treatment, even when there is no change in tumor size. The approach provides a quantitative and therefore objective assessment of treatment response that could be used with other types of MR image and also with other imaging modalities. PMID:23440731

Larkin, Timothy J; Canuto, Holly C; Kettunen, Mikko I; Booth, Thomas C; Hu, De-En; Krishnan, Anant S; Bohndiek, Sarah E; Neves, André A; McLachlan, Charles; Hobson, Michael P; Brindle, Kevin M



2D and 3D MALDI-imaging: Conceptual strategies for visualization and data mining.  


3D imaging has a significant impact on many challenges in life sciences, because biology is a 3-dimensional phenomenon. Current 3D imaging-technologies (various types MRI, PET, SPECT) are labeled, i.e. they trace the localization of a specific compound in the body. In contrast, 3D MALDI mass spectrometry-imaging (MALDI-MSI) is a label-free method imaging the spatial distribution of molecular compounds. It complements 3D imaging labeled methods, immunohistochemistry, and genetics-based methods. However, 3D MALDI-MSI cannot tap its full potential due to the lack of statistical methods for analysis and interpretation of large and complex 3D datasets. To overcome this, we established a complete and robust 3D MALDI-MSI pipeline combined with efficient computational data analysis methods for 3D edge preserving image denoising, 3D spatial segmentation as well as finding colocalized m/z values, which will be reviewed here in detail. Furthermore, we explain, why the integration and correlation of the MALDI imaging data with other imaging modalities allows to enhance the interpretation of the molecular data and provides visualization of molecular patterns that may otherwise not be apparent. Therefore, a 3D data acquisition workflow is described generating a set of 3 different dimensional images representing the same anatomies. First, an in-vitro MRI measurement is performed which results in a three-dimensional image modality representing the 3D structure of the measured object. After sectioning the 3D object into N consecutive slices, all N slices are scanned using an optical digital scanner, enabling for performing the MS measurements. Scanning the individual sections results into low-resolution images, which define the base coordinate system for the whole pipeline. The scanned images conclude the information from the spatial (MRI) and the mass spectrometric (MALDI-MSI) dimension and are used for the spatial three-dimensional reconstruction of the object performed by image registration techniques. Different strategies for automatic serial image registration applied to MS datasets are outlined in detail. The third image modality is histology driven, i.e. a digital scan of the histological stained slices in high-resolution. After fusion of reconstructed scan images and MRI the slice-related coordinates of the mass spectra can be propagated into 3D-space. After image registration of scan images and histological stained images, the anatomical information from histology is fused with the mass spectra from MALDI-MSI. As a result of the described pipeline we have a set of 3 dimensional images representing the same anatomies, i.e. the reconstructed slice scans, the spectral images as well as corresponding clustering results, and the acquired MRI. Great emphasis is put on the fact that the co-registered MRI providing anatomical details improves the interpretation of 3D MALDI images. The ability to relate mass spectrometry derived molecular information with in vivo and in vitro imaging has potentially important implications. This article is part of a Special Issue entitled: Computational Proteomics in the Post-Identification Era. PMID:23467008

Thiele, Herbert; Heldmann, Stefan; Trede, Dennis; Strehlow, Jan; Wirtz, Stefan; Dreher, Wolfgang; Berger, Judith; Oetjen, Janina; Kobarg, Jan Hendrik; Fischer, Bernd; Maass, Peter



Assessing 3D tunnel position in ACL reconstruction using a novel single image 3D-2D registration  

NASA Astrophysics Data System (ADS)

The routinely used procedure for evaluating tunnel positions following anterior cruciate ligament (ACL) reconstructions based on standard X-ray images is known to pose difficulties in terms of obtaining accurate measures, especially in providing three-dimensional tunnel positions. This is largely due to the variability in individual knee joint pose relative to X-ray plates. Accurate results were reported using postoperative CT. However, its extensive usage in clinical routine is hampered by its major requirement of having CT scans of individual patients, which is not available for most ACL reconstructions. These difficulties are addressed through the proposed method, which aligns a knee model to X-ray images using our novel single-image 3D-2D registration method and then estimates the 3D tunnel position. In the proposed method, the alignment is achieved by using a novel contour-based 3D-2D registration method wherein image contours are treated as a set of oriented points. However, instead of using some form of orientation weighting function and multiplying it with a distance function, we formulate the 3D-2D registration as a probability density estimation using a mixture of von Mises-Fisher-Gaussian (vMFG) distributions and solve it through an expectation maximization (EM) algorithm. Compared with the ground-truth established from postoperative CT, our registration method in an experiment using a plastic phantom showed accurate results with errors of (-0.43°+/-1.19°, 0.45°+/-2.17°, 0.23°+/-1.05°) and (0.03+/-0.55, -0.03+/-0.54, -2.73+/-1.64) mm. As for the entry point of the ACL tunnel, one of the key measurements, it was obtained with high accuracy of 0.53+/-0.30 mm distance errors.

Kang, X.; Yau, W. P.; Otake, Y.; Cheung, P. Y. S.; Hu, Y.; Taylor, R. H.



Experimental demonstration of diffusion signal enhancement in 2D DESIRE images.  


In magnetic resonance microscopy based on conventional Fourier encoding techniques, molecular self-diffusion leads to a loss in signal to noise ratio while also limiting the spatial resolution. As opposed to standard diffusion-weighted sequences, the DESIRE (Diffusion Enhancement of SIgnal and REsolution) method gains signal through diffusion via a signal difference measurement, corresponding to the total number of spins saturated by a localized pulse applied for a given amount of time. The higher the diffusion coefficient at that location, the larger the number of spins effectively saturated and thus the higher the difference in signal. While the method has been previously demonstrated in 1D, the availability of higher magnetic fields and gradient strengths has recently brought its development within reach in 2D. Here we report the implementation of 2D DESIRE and the first experimental evaluation of enhancements in water and thin silicone oil. Enhancement levels obtained by saturating a 60 ?m diameter region (effectively ~140 ?m) and allowing diffusion lengths of 28 ?m or 7 ?m, respectively, are consistent with theoretical predictions. The typical enhancement values are 100% in water and 20% in silicone oil. PMID:22578554

Jelescu, Ileana O; Boulant, Nicolas; Le Bihan, Denis; Ciobanu, Luisa



Experimental demonstration of diffusion signal enhancement in 2D DESIRE images  

NASA Astrophysics Data System (ADS)

In magnetic resonance microscopy based on conventional Fourier encoding techniques, molecular self-diffusion leads to a loss in signal to noise ratio while also limiting the spatial resolution. As opposed to standard diffusion-weighted sequences, the DESIRE (Diffusion Enhancement of SIgnal and REsolution) method gains signal through diffusion via a signal difference measurement, corresponding to the total number of spins saturated by a localized pulse applied for a given amount of time. The higher the diffusion coefficient at that location, the larger the number of spins effectively saturated and thus the higher the difference in signal. While the method has been previously demonstrated in 1D, the availability of higher magnetic fields and gradient strengths has recently brought its development within reach in 2D. Here we report the implementation of 2D DESIRE and the first experimental evaluation of enhancements in water and thin silicone oil. Enhancement levels obtained by saturating a 60 ?m diameter region (effectively ˜140 ?m) and allowing diffusion lengths of 28 ?m or 7 ?m, respectively, are consistent with theoretical predictions. The typical enhancement values are 100% in water and 20% in silicone oil.

Jelescu, Ileana O.; Boulant, Nicolas; Le Bihan, Denis; Ciobanu, Luisa



Direct observation of ground-state lactam-lactim tautomerization using temperature-jump transient 2D IR spectroscopy.  


We provide a systematic characterization of the nanosecond ground-state lactam-lactim tautomerization of pyridone derivatives in aqueous solution under ambient conditions using temperature-jump transient 2D IR spectroscopy. Although electronic excited-state tautomerization has been widely studied, experimental work on the ground electronic state, most relevant to chemistry and biology, is lacking. Using 2D IR spectroscopy, lactam and lactim tautomers of 6-chloro-2-pyridone and 2-chloro-4-pyridone are unambiguously identified by their unique cross-peak patterns. Monitoring the correlated exponential relaxation of these signals in response to a laser temperature jump provides a direct measurement of the nanosecond tautomerization kinetics. By studying the temperature, concentration, solvent, and pH dependence, we extract a thermodynamic and kinetic characterization and conclude that the tautomerization proceeds through a two-state concerted mechanism. We find that the intramolecular proton transfer is mediated by bridging water molecules and the reaction barrier is dictated by the release of a proton from pyridone, as would be expected for an efficient Grothuss-type proton transfer mechanism. PMID:23690588

Peng, Chunte Sam; Baiz, Carlos R; Tokmakoff, Andrei



Comparison of registration techniques for speckle suppression in 2D ladar image sequences  

NASA Astrophysics Data System (ADS)

Registration of individual images remains a significant problem in the generation of accurate images collected using coherent imaging systems. An investigation of the performance of eight distinct image registration algorithms was conducted using data collected from a coherent optical imaging system developed by the Air Force Research Laboratories, Sensors Division, ARFL/SNJT. A total of 400 images of three distinct scenes were collected by SRJT and made available to the Air Force Institute of Technology (AFIT) for this study. Scenery was collected at 3 and 10 kilometers of wheeled vehicles supporting resolution and uniform target boards. The algorithms under study were developed by scientists and engineers at AFRL, and had varying levels of performance in terms of image mis-registration and execution time. These eight algorithms were implemented on a general-purpose computer running the MATLAB simulation environment. The algorithms compared included: block-match, cross-correlation, cross-search, directional-search, gradient-based, hierarchical-block, three-step, and vector-block methods. It was found that the cross-correlation, gradient-based and vector-block search techniques typically had the lowest error metric. The vector-block and cross-correlation methods proved to have the fastest execution times, while not suffering significant error degradation when estimating the registration shift of the test images.

MacDonald, Adam; Armstrong, Ernest; Cain, Stephen C.



Attenuation of 2D specularly-reected multiples in image space  

Microsoft Academic Search

I propose a new method to attenuate specularly-reect ed multiples in the image space. The method is based on the difference in mapping between primaries and multiples in Subsurface Offset Domain Common Image Gathers (SODCIGs). I migrate the data with a velocity slower than that of the primaries but faster than that of the multiples. The pri- maries are therefore

Gabriel Alvarez


New Insights to the Sawtooth Oscillation (m/n=1/1 mode) in Hot Plasmas based on High Resolution 2-D Images of Te Fluctuations  

SciTech Connect

Two dimensional (2-D) images of electron temperature fluctuations with high temporal and spatial resolution have been employed to study the sawtooth oscillation (m/n=1/1 mode) in Toroidal EXperiment for Technology Oriented Research (TEXTOR) tokamak plasmas. 2-D imaging data revealed new physics which were not available in previous studies based on the 1-D electron temperature measurement and X-ray tomography. Review of the physics of the sawtooth oscillation is given by comparative studies with prominent theoretical models suggest that a new physics paradigm is needed to describe the reconnection physics of the sawtooth oscillation. The new insights are: A pressure driven instability (not a ballooning mode) leads to the X-point reconnection process. The reconnection process is identified as a random 3-D local reconnection process with a helical structure. The reconnection time scale is similar for different types of sawtooth oscillation ("kink" and tearing type) and is significantly faster than the resistive time scale. Heat flow from the core to the outside of the inversion radius during the reconnection process is highly collective rather than stochastic.

H.K. Park, N.C. Luhmann, Jr, A.J.H. Donné, C.W. Domier, T. Munsat, M.J. Van de Pol, and the TEXTOR Team




Microsoft Academic Search

In this numerical work, two-dimensional rich premixed laminar methane-air flames are calculated in detail. Emphasis is laid on the comparative analysis of spatial distributions of CO concentrations and temperature for a range of mixtures using two reaction mechanisms, and thereby reporting on the suitability of such mechanisms. A test analysis showed that the results from the present numerical scheme are




2D and 3D sub-diffraction source imaging with a superoscillatory filter.  


In this paper, we propose an approach to overcome the well-known "diffraction limit" when imaging sources several wavelengths away. We employ superdirectivity antenna concepts to design a well-controlled superoscillatory filter (SOF) based on the properties of Tschebyscheff polynomials. The SOF is applied to the reconstructed images from holographic algorithms which are based on the back-propagation principle. We demonstrate the capability of this approach when imaging point-sources several wavelengths away in one-, two-, and three-dimensional imaging with super-resolution. We also investigate the robustness of the proposed algorithm with the sharpness of the SOF, the presence of noise, the imaging distance, and the size of the scanning aperture. PMID:23571904

Amineh, Reza K; Eleftheriades, George V



Proton temperature anisotropy and current sheet stability: 2-D hybrid simulations  

NASA Astrophysics Data System (ADS)

The solar wind is a weakly collisional non homogeneous plasma; gradients associated to density, velocity shears and current sheets are often observed. In situ observations also show that the solar wind plasma is far from thermal equilibrium and particle distribution functions are not isotropic. The presence of a temperature anisotropy can be the source of free energy for kinetic instabilities and their unstable fluctuations may grow and propagate in the plasma. However, how these fluctuations evolve in a non homogeneous medium and how they interact and influence local coherent structures, is still an open question. We report preliminary numerical simulations that describe the evolution of current sheets in a non thermal plasma, focusing on the interaction between kinetic effects driven by a proton temperature anisotropy and magnetic reconnection processes.

Matteini, Lorenzo; Landi, Simone; Velli, Marco; Matthaeus, William H.



3-D portal image analysis in clinical practice: an evaluation of 2-D and 3-D analysis techniques as applied to 30 prostate cancer patients  

Microsoft Academic Search

Purpose: To investigate the clinical importance and feasibility of a 3-D portal image analysis method in comparison with a standard 2-D portal image analysis method for pelvic irradiation techniques.Methods and Materials: In this study, images of 30 patients who were treated for prostate cancer were used. A total of 837 imaged fields were analyzed by a single technologist, using automatic

Peter Remeijer; Erik Geerlof; Lennert Ploeger; Kenneth Gilhuijs; Marcel van Herk; Joos V Lebesque



Temperature-dependent quantum electron transport in 2D point contacts.  


We consider the transmission of electrons through a two-dimensional ballistic point contact in the low-conductance regime near the pinch-off region. The scattering of electrons by Friedel oscillations of charge density results in a contribution to the conductance proportional to the temperature. The sign of this linear term depends on the range of the electron-electron interaction and appears to be negative for the relevant experimental parameters. PMID:23288558

Krishtop, T V; Nagaev, K E



High-resolution human diffusion tensor imaging using 2-D navigated multishot SENSE EPI at 7 T.  


The combination of parallel imaging with partial Fourier acquisition has greatly improved the performance of diffusion-weighted single-shot EPI and is the preferred method for acquisitions at low to medium magnetic field strength such as 1.5 or 3 T. Increased off-resonance effects and reduced transverse relaxation times at 7 T, however, generate more significant artifacts than at lower magnetic field strength and limit data acquisition. Additional acceleration of k-space traversal using a multishot approach, which acquires a subset of k-space data after each excitation, reduces these artifacts relative to conventional single-shot acquisitions. However, corrections for motion-induced phase errors are not straightforward in accelerated, diffusion-weighted multishot EPI because of phase aliasing. In this study, we introduce a simple acquisition and corresponding reconstruction method for diffusion-weighted multishot EPI with parallel imaging suitable for use at high field. The reconstruction uses a simple modification of the standard sensitivity-encoding (SENSE) algorithm to account for shot-to-shot phase errors; the method is called image reconstruction using image-space sampling function (IRIS). Using this approach, reconstruction from highly aliased in vivo image data using 2-D navigator phase information is demonstrated for human diffusion-weighted imaging studies at 7 T. The final reconstructed images show submillimeter in-plane resolution with no ghosts and much reduced blurring and off-resonance artifacts. PMID:22592941

Jeong, Ha-Kyu; Gore, John C; Anderson, Adam W



Magnetic resonance image reconstruction using trained geometric directions in 2D redundant wavelets domain and non-convex optimization.  


Reducing scanning time is significantly important for MRI. Compressed sensing has shown promising results by undersampling the k-space data to speed up imaging. Sparsity of an image plays an important role in compressed sensing MRI to reduce the image artifacts. Recently, the method of patch-based directional wavelets (PBDW) which trains geometric directions from undersampled data has been proposed. It has better performance in preserving image edges than conventional sparsifying transforms. However, obvious artifacts are presented in the smooth region when the data are highly undersampled. In addition, the original PBDW-based method does not hold obvious improvement for radial and fully 2D random sampling patterns. In this paper, the PBDW-based MRI reconstruction is improved from two aspects: 1) An efficient non-convex minimization algorithm is modified to enhance image quality; 2) PBDW are extended into shift-invariant discrete wavelet domain to enhance the ability of transform on sparsifying piecewise smooth image features. Numerical simulation results on vivo magnetic resonance images demonstrate that the proposed method outperforms the original PBDW in terms of removing artifacts and preserving edges. PMID:23992629

Ning, Bende; Qu, Xiaobo; Guo, Di; Hu, Changwei; Chen, Zhong



2D and 3D Refraction Based X-ray Imaging Suitable for Clinical and Pathological Diagnosis  

SciTech Connect

The first observation of micro papillary (MP) breast cancer by x-ray dark-field imaging (XDFI) and the first observation of the 3D x-ray internal structure of another breast cancer, ductal carcinoma in-situ (DCIS), are reported. The specimen size for the sheet-shaped MP was 26 mm x 22 mm x 2.8 mm, and that for the rod-shaped DCIS was 3.6 mm in diameter and 4.7 mm in height. The experiment was performed at the Photon Factory, KEK: High Energy Accelerator Research Organization. We achieved a high-contrast x-ray image by adopting a thickness-controlled transmission-type angular analyzer that allows only refraction components from the object for 2D imaging. This provides a high-contrast image of cancer-cell nests, cancer cells and stroma. For x-ray 3D imaging, a new algorithm due to the refraction for x-ray CT was created. The angular information was acquired by x-ray optics diffraction-enhanced imaging (DEI). The number of data was 900 for each reconstruction. A reconstructed CT image may include ductus lactiferi, micro calcification and the breast gland. This modality has the possibility to open up a new clinical and pathological diagnosis using x-ray, offering more precise inspection and detection of early signs of breast cancer.

Ando, Masami [Institute of Science and Technology, Tokyo Univ. of Science, Yamasaki 2641, Noda, Chiba 278-8510 (Japan); Photon Factory, IMSS, KEK, Oho 1-1, Tsukuba, Ibaraki 305-0801 (Japan); Dept. of Photo-Science, GUAS, Shonan, Hayama, Kanagawa 240-0193 (Japan); Bando, Hiroko; Ueno, Ei [Dept. of Breast-Thyroid-Endocrine Surgery, Univ. of Tsukuba, Ibaraki 305-8573 (Japan)] (and others)



Ultraviolet 2D fluorescence mapping system for the imaging of head and neck tumors  

NASA Astrophysics Data System (ADS)

Fluorescence images of ex vivo head and neck tissues were acquired at multiple combinations of emission and excitation wavelengths. The wavelength combinations were selected to map different tissue molecules and structures whose fluorescence signatures have bene used to detect cancer. Fluorescence maps were generated by ratioing fluorescence image intensities. These ratio maps enhanced the ability to recognize regions of tumor and other features in tissues. Histopathological analysis was performed on the tissue samples. Location and shape of features observed in the fluorescence images were correlated with structures observed in histopathology.

Katz, Alvin; Savage, Howard E.; Zeng, Fan-An; Rome, Jayson; Schantz, Stimson P.; McCormick, Steven A.; Cocker, Rubina S.; Alfano, Robert R.



New insights in a 2-D hard disk system under a temperature gradient  

NASA Astrophysics Data System (ADS)

Hard Disks system is a paradicmatic model well suited, numericaly, to test new approaches to nonequi-librium fenomena, being also easy and fast to simulate due to efficient event driven algorithms present in the literature. In this poster we study several properties of the model under a temperature gradient on the stationary regime. In this situation the sistem has well defined gradients in temperatures and densities allowing us to calculate experimentaly the thermal conductivity. We found this result compatible with the Enskog expresion even for large gradients. We also check that Henderson's state equation, although is an expresion derived under equilibrium conditions, is valid in our system for a wide range of temperatures gradients. We explain this fact showing that the system reach a local thermal equilibrium. Finaly we focus on the role of fluctuations of the energy current finding good agreement with the, recently introduced, Isometric Fluctuation Relation (IFR). We conclude that IFR also stands in our system, although it was formulated from a much simpler case.

Del Pozo, J. J.; Pérez-Espigares, C.; Hurtado, P. I.; Garrido, P. L.



Graphene-assisted room-temperature synthesis of 2D nanostructured hybrid electrode materials: dramatic acceleration of the formation rate of 2D metal oxide nanoplates induced by reduced graphene oxide nanosheets.  


A new prompt room temperature synthetic route to 2D nanostructured metal oxide-graphene-hybrid electrode materials can be developed by the application of colloidal reduced graphene oxide (RGO) nanosheets as an efficient reaction accelerator for the synthesis of ?-MnO2 2D nanoplates. Whereas the synthesis of the 2D nanostructured ?-MnO2 at room temperature requires treating divalent manganese compounds with persulfate ions for at least 24 h, the addition of RGO nanosheet causes a dramatic shortening of synthesis time to 1 h, underscoring its effectiveness for the promotion of the formation of 2D nanostructured metal oxide. To the best of our knowledge, this is the first example of the accelerated synthesis of 2D nanostructured hybrid material induced by the RGO nanosheets. The observed acceleration of nanoplate formation upon the addition of RGO nanosheets is attributable to the enhancement of the oxidizing power of persulfate ions, the increase of the solubility of precursor MnCO3, and the promoted crystal growth of ?-MnO2 2D nanoplates. The resulting hybridization between RGO nanosheets and ?-MnO2 nanoplates is quite powerful not only in increasing the surface area of manganese oxide nanoplate but also in enhancing its electrochemical activity. Of prime importance is that the present ?-MnO2 -RGO nanocomposites show much superior electrode performance over most of 2D nanostructured manganate systems including a similar porous assembly of RGO and layered MnO2 nanosheets. This result underscores that the present RGO-assisted solution-based synthesis can provide a prompt and scalable method to produce nanostructured hybrid electrode materials. PMID:23559338

Sung, Da-Young; Gunjakar, Jayavant L; Kim, Tae Woo; Kim, In Young; Lee, Yu Ri; Hwang, Seong-Ju



Turbulent Plasma Fluctuations are Measured Using 2-D Fast Phosphor Diagnostic Imaging Techniques  

NASA Astrophysics Data System (ADS)

A plasma imaging diagnostic is being developed using a fast time response phosphor to detect and follow plasma density fluctuations in a two-dimensional linear plasma device. The diagnostic consists of a phosphor coated quartz disk [diameter = 9.8 cm] enabling one to image the entire cross-section of the plasma column at one time. Plasma density fluctuations are imaged by their associated electron excitation of the phosphor screen. The fast response of the phosphor [persistence time = 1 microsecond] combined with fast electronic camera shutter speeds enables imaging of the evolution of plasma fluctuations with microsecond time resolution. The characteristic 2-50 microsecond time scale turbulent phosphor light fluctuations in PISCES-A are studied and compared with local Langmuir probe measurements of density fluctuations.

Liebscher, Andreas; Luckhardt, Stan; Zweben, Stewart



Testing the limitations of 2-D companding for strain imaging using phantoms  

Microsoft Academic Search

Companding may be used as a technique for generating low-noise strain images. It involves warping radio-frequency echo fields in two dimensions and at several spatial scales to minimize decorrelation errors in correlation-based displacement estimates. For the appropriate experimental conditions, companding increases the sensitivity and dynamic range of strain images without degrading contrast or spatial resolution significantly. In this paper, we

Pawan Chaturvedi; Michael F. Insana; Timothy J. Hall



Registration of 2D to 3D joint images using phase-based mutual information  

NASA Astrophysics Data System (ADS)

Registration of two dimensional to three dimensional orthopaedic medical image data has important applications particularly in the area of image guided surgery and sports medicine. Fluoroscopy to computer tomography (CT) registration is an important case, wherein digitally reconstructed radiographs derived from the CT data are registered to the fluoroscopy data. Traditional registration metrics such as intensity-based mutual information (MI) typically work well but often suffer from gross misregistration errors when the image to be registered contains a partial view of the anatomy visible in the target image. Phase-based MI provides a robust alternative similarity measure which, in addition to possessing the general robustness and noise immunity that MI provides, also employs local phase information in the registration process which makes it less susceptible to the aforementioned errors. In this paper, we propose using the complex wavelet transform for computing image phase information and incorporating that into a phase-based MI measure for image registration. Tests on a CT volume and 6 fluoroscopy images of the knee are presented. The femur and the tibia in the CT volume were individually registered to the fluoroscopy images using intensity-based MI, gradient-based MI and phase-based MI. Errors in the coordinates of fiducials present in the bone structures were used to assess the accuracy of the different registration schemes. Quantitative results demonstrate that the performance of intensity-based MI was the worst. Gradient-based MI performed slightly better, while phase-based MI results were the best consistently producing the lowest errors.

Dalvi, Rupin; Abugharbieh, Rafeef; Pickering, Mark; Scarvell, Jennie; Smith, Paul



An active microwave imaging system for reconstruction of 2-D electrical property distributions  

Microsoft Academic Search

The goal of this work is to develop a microwave-based imaging system for hyperthermia treatment monitoring and assessment. Toward this end, a 4-transmit channel and 4-receive channel hardware device and concomitant image reconstruction algorithm have been realized. The hardware is designed to measure electric fields (i.e., amplitude and phase) at various locations in a phantom tank with and without the

Paul M. Meaney; Keith D. Paulsen; Alexander Hartov; Robert K. Crane



2D imaging of an undulator source by phase circular Bragg-Fresnel lens  

Microsoft Academic Search

Two-dimensional imaging of an undulator x-ray source at different photon energies has been observed by means of phase circular Bragg–Fresnel lens (BFL) at the ESRF ID6 beamline. The optical properties of the BFL in the energy range 6–18 keV have been studied. Imaging has been studied on various orders of diffraction and on various harmonics of the undulator spectrum. Good

E. Tarazona; P. Elleaume; J. Chavanne; Ya. M. Hartman; A. A. Snigirev; I. I. Snigireva



A new SIMS paradigm for 2D and 3D molecular imaging of bio-systems.  


With the implementation of focused primary ion beams, secondary ion mass spectrometry (SIMS) has become a significant technique in the rapidly emerging field of mass spectral imaging in the biological sciences. Liquid metal ion guns (LMIG) offered the prospect of sub-100 nm spatial resolution, however this aspiration has yet to be reached for molecular imaging. This brief review shows that using LMIG the limitations of the static limit and low ionization probability will restrict useful imaging to around 2 mum spatial resolution with high-yield molecules. The only prospect of going beyond this in the absence of factors of 100 increase in ionization probability is to use polyatomic ion beams such as C (60) (+) , for which bombardment induced damage is low. In these cases sub-micron imaging becomes possible, using voxels together with molecular depth profiling and 3D imaging. The discussion shows that conventional ToF-SIMS instrumentation then becomes a limitation in that the pulsed ion beam has a very low duty cycle which results in inordinately long analysis times, and pulsing the beam means that high-mass resolution and high spatial resolution are mutually incompatible. New instrumental configurations are described that allow the use of a dc ion beam and separate the mass spectrometry for the ion formation process. Early results from these instruments suggest that sub-micron analysis and imaging with high mass resolution and good ion yields are now realizable, although the low ion yield issue still needs to be solved. PMID:19669735

Fletcher, John S; Vickerman, John C



Extracting paleoclimate signals from sediment laminae: An automated 2-D image processing method  

NASA Astrophysics Data System (ADS)

Lake sediments commonly contain laminations and the occurrence and quantitative attributes of these microstrata contain signals of their depositional environment, limnological conditions, and past climate. However, the identification and measurement of laminae and their attributes remains a largely semi-manual process that is tedious, labor intensive, but subject to human error. Here, we present a method to automatically measure and accurately extract lamina properties from sediment core images. This method is comprised of four major components: (1) image enhancement that includes noise reduction and contrast enhancement to improve signal-to-background ratio and resolution of laminae; (2) identification of 1-D laminae for a user-chosen area in an image; (3) laminae connectivity analyses on the 1-D laminae to obtain a lamina stratigraphy; and (4) extraction and retrieval of the primary and derived lamination stratigraphic data. Sediment core images from Lake Hitchcock and Lake Bosumtwi were used for algorithm development and testing. Our experiments show a complete match between laminae produced by the software and manual process for images from Lake Hitchcock. Quantitative comparisons reveal an insignificant discrepancy in the number of laminae identified automatically by the software and manually by researchers, and in over 90% of the cases the position mismatch of individual laminae is less than one pixel between the software and the manual method for the experimental images from Lake Bosumtwi.

Gan, Stoney Q.; Scholz, Christopher A.



Methionine Adenosyltransferase ?-Helix Structure Unfolds at Lower Temperatures than ?-Sheet: A 2D-IR Study  

PubMed Central

Two-dimensional infrared spectroscopy has been used to characterize rat liver methionine adenosyltransferase and the events taking place during its thermal unfolding. Secondary structure data have been obtained for the native recombinant enzyme by fitting the amide I band of infrared spectra. Thermal denaturation studies allow the identification of events associated with individual secondary-structure elements during temperature-induced unfolding. They are correlated to the changes observed in enzyme activity and intrinsic fluorescence. In all cases, thermal denaturation proved to be an irreversible process, with a Tm of 47–51°C. Thermal profiles and two-dimensional infrared spectroscopy show that unfolding starts with ?-helical segments and turns, located in the outer part of the protein, whereas extended structure, associated with subunit contacts, unfolds at higher temperatures. The data indicate a good correlation between the denaturation profiles obtained from activity measurements, fluorescence spectroscopy, and the behavior of the infrared bands. A study of the sequence of events that takes place is discussed in light of the previous knowledge on methionine adenosyltransferase structure and oligomerization pathway.

Iloro, Ibon; Chehin, Rosana; Goni, Felix M.; Pajares, Maria A.; Arrondo, Jose-Luis R.



An approach to 2D\\/3D registration of a vertebra in 2D X-ray fluoroscopies with 3D CT images  

Microsoft Academic Search

In order to use pre-operative images during an operation for navigation, they must be registered to the patient's coordinate system in the operating theater or to an intra-operative image. One problem in this area is the registration of a vertebra in intra-operatively acquired x-ray fluoroscopies with 3D CT images obtained before the intervention. The result can be used to support

Jtirgen Weese; Thorsten M. Buzug; Cristian Lorenz; Carola Fassnacht



Extraction and comparison of gene expression patterns from 2D RNA in situ hybridization images  

PubMed Central

Motivation: Recent advancements in high-throughput imaging have created new large datasets with tens of thousands of gene expression images. Methods for capturing these spatial and/or temporal expression patterns include in situ hybridization or fluorescent reporter constructs or tags, and results are still frequently assessed by subjective qualitative comparisons. In order to deal with available large datasets, fully automated analysis methods must be developed to properly normalize and model spatial expression patterns. Results: We have developed image segmentation and registration methods to identify and extract spatial gene expression patterns from RNA in situ hybridization experiments of Drosophila embryos. These methods allow us to normalize and extract expression information for 78 621 images from 3724 genes across six time stages. The similarity between gene expression patterns is computed using four scoring metrics: mean squared error, Haar wavelet distance, mutual information and spatial mutual information (SMI). We additionally propose a strategy to calculate the significance of the similarity between two expression images, by generating surrogate datasets with similar spatial expression patterns using a Monte Carlo swap sampler. On data from an early development time stage, we show that SMI provides the most biologically relevant metric of comparison, and that our significance testing generalizes metrics to achieve similar performance. We exemplify the application of spatial metrics on the well-known Drosophila segmentation network. Availability: A Java webstart application to register and compare patterns, as well as all source code, are available from: Contact: Supplementary information: Supplementary data are available at Bioinformatics online.

Mace, Daniel L.; Varnado, Nicole; Zhang, Weiping; Frise, Erwin; Ohler, Uwe



Implementation of the 2-D Wavelet Transform into FPGA for Image  

NASA Astrophysics Data System (ADS)

This paper presents a hardware system implementation of the of discrete wavelet transform algoritm in two dimensions for FPGA, using the Daubechies filter family of order 2 (db2). The decomposition algorithm of this transform is designed and simulated with the Hardware Description Language VHDL and is implemented in a programmable logic device (FPGA) XC3S1200E reference, Spartan IIIE family, by Xilinx, take advantage the parallels properties of these gives us and speeds processing that can reach them. The architecture is evaluated using images input of different sizes. This implementation is done with the aim of developing a future images encryption hardware system using wavelet transform for security information.

León, M.; Barba, L.; Vargas, L.; Torres, C. O.



Detailed 2-D imaging of the Mediterranean outflow and meddies off W Iberia from multichannel seismic data  

Microsoft Academic Search

Reprocessing of a 326-km long multichannel seismic line acquired in the Tagus Abyssal Plain off W Iberia in 1991 allowed detailed imaging of the thermohaline structure of several mesoscale features within the water column. The interpretation was supported by subsurface float measurements, Sea Level Anomaly (SLA) maps and Sea Surface Temperature (SST) images contemporaneous with the acquisition of the seismic

Luis Menezes Pinheiro; Haibin Song; Barry Ruddick; Jesus Dubert; Isabel Ambar; Kamran Mustafa; Ronaldo Bezerra



Rotation of NMR images using the 2D chirp-z transform.  


A quick and accurate way to rotate and shift nuclear magnetic resonance (NMR) images using the two-dimensional chirp-z transform is presented. When the desired image grid is rotated and shifted from the original grid due to patient motion, the chirp-z transform can reconstruct NMR images directly onto the ultimate grid instead of reconstructing onto the original grid and then applying interpolation to get the final real-space image in the conventional way. The rotation angle and shift distances are embedded in the parameters of the chirp-z transform. The chirp-z transform implements discrete sinc interpolation to get values at grid points that are not exactly on the original grid when applying the inverse Fourier transform. Therefore, the chirp-z transform is more accurate than methods such as linear or bicubic interpolation and is more efficient than direct implementation of sinc interpolation because the sinc interpolation is implemented at the same time as reconstruction from k-space. PMID:10080271

Tong, R; Cox, R W



Object Tracking by Kalman Filtering and Recursive Least Squares Based on 2D Image Motion  

Microsoft Academic Search

This paper proposes a novel tracking strategy that can robustly track an object within a fixed environment. We define a robust model-based tracker using Kalman filtering combined with recursive least squares. The tracking is done by fitting successively more elaborate models on the tracked region and the segmentation is done by extracting the regions of the image that are consistent

Feng Yi-wei; Guo Ge; Zhu Chao-qun



Target Identification of an Antibacterial Compound from Data Mining of 2-D Gel Images  

Microsoft Academic Search

Drug discovery program is a complex scientific process, with very low successful rate of 1\\/5000 compounds, which might be further developed for therapeutic usage. To accelerate the drug discovery process, new “omics” technology has been used. We have described how to use proteomics technology of two-dimensioal gel to identify the protein target of an antibacterial compound. The digital images of

KuoYuan Hwa; Di-Shuan Chiang; Chen-Wen Yao



Wavelet-based 2D Multifractal Spectrum with Applications in Analysis of Digital Mammography Images  

Microsoft Academic Search

Breast cancer is the second leading cause of death in women in the United States and at present, mammography is the only proven method that can detect minimal breast cancer. On the other hand, many medical images demonstrate a certain degree of self-similarity over a range of scales. The Multifractal spectrum (MFS) summarizes possibly variable degrees of scaling in one

Pepa Ram; Brani Vidakovic


Extracting Buildings from Aerial Images Using Hierarchical Aggregation in 2D and 3D  

Microsoft Academic Search

We propose a model-based approach to automated 3D extraction of buildings fromaerial images. We focus on a reconstruction strategy that is not restricted to a small classof buildings. Therefore, we employ a generic modeling approach which relies on the welldened combination of building part models. Building parts are classied by their roof type.

André Fischer; Thomas H. Kolbe; Felicitas Lang; Armin B. Cremers; Wolfgang Förstner; Lutz Plümer; Volker Steinhage



Endoscopic 2D particle image velocimetry (PIV) flow field measurements in IC engines  

NASA Astrophysics Data System (ADS)

The paper describes camera and laser endoscopes designed for particle image velocimetry (PIV) applications like measurements in IC engines or turbomachinery. Endoscopic PIV measurements through 8-mm optical access on an IC engine are presented and compared with the measurements using standard optical access through a window.

Dierksheide, U.; Meyer, P.; Hovestadt, T.; Hentschel, W.



Effects of Bias Frequency on 2D Image of Net Production Rate in Two Frequency CCP  

NASA Astrophysics Data System (ADS)

Two frequency capacitively-coupled plasma(2f-CCP) is a major processing tool for SiO2 etching. It is important to optimize the bias frequency for both a control of the ion energy on the wafer and a radial uniformity of 2f-CCP. Effect of bias frequency on 2D(r,z) profiles of axisymmetric 2f-CCP in CF_4/Ar at 25mTorr is investigated by time-resolved OES. Bias frequency in a range of 339kHz ~2.71MHz is applied to the 2f-CCP excited at 13.56MHz. For bias frequencies of 339kHz and 678kHz, the radial uniformity of the net excitation rate of probed-Ar(2p_1) is strongly affected by the bias voltage amplitude due to the excess excitation caused by high energy electrons at the central axis. Radial uniformity is improved for the bias frequency higher than 1.35MHz. The effect of bias frequency is also shown for the temporal variation of the net excitation rate during one bias period. The net rate changes by 50% at 1.35MHz, while it changes by 200% at 678kHz. The effect of secondary electrons from the bias electrode is suppressed in case of 1.35MHz by a temporal trapping. Optimization of the bias frequency above 1MHz becomes a key to enable the bimodal energy distribution of ion on the wafer surface and the radial uniformity of 2f-CCP. Results of VHF(100MHz) excitation and the detail of the sustaining mechanism of 2f-CCP during one RF period are also discussed.

Kitajima, T.; Fujita, T.; Mano, T.; Makabe, T.



An automatic 2D-3D image matching method for reproducing spatial knee joint positions using single or dual fluoroscopic images.  


Fluoroscopic image technique, using either a single image or dual images, has been widely applied to measure in vivo human knee joint kinematics. However, few studies have compared the advantages of using single and dual fluoroscopic images. Furthermore, due to the size limitation of the image intensifiers, it is possible that only a portion of the knee joint could be captured by the fluoroscopy during dynamic knee joint motion. In this paper, we presented a systematic evaluation of an automatic 2D-3D image matching method in reproducing spatial knee joint positions using either single or dual fluoroscopic image techniques. The data indicated that for the femur and tibia, their spatial positions could be determined with an accuracy and precision less than 0.2 mm in translation and less than 0.4° in orientation when dual fluoroscopic images were used. Using single fluoroscopic images, the method could produce satisfactory accuracy in joint positions in the imaging plane (in average up to 0.5 mm in translation and 1.3° in rotation), but large variations along the out-plane direction (in average up to 4.0 mm in translation and 2.2° in rotation). The precision of using single fluoroscopic images to determine the actual knee positions was worse than its accuracy obtained. The data also indicated that when using dual fluoroscopic image technique, if the knee joint outlines in one image were incomplete by 80%, the algorithm could still reproduce the joint positions with high precisions. PMID:21806411

Zhu, Zhonglin; Li, Guoan




PubMed Central

Many recent studies on ultrasonic particle image velocimetry (Echo PIV) showed that the accuracy of two-dimensional (2-D) flow velocity measured depends largely on the concentration of ultrasound contrast agents (UCAs) during imaging. This article presents a texture-based method for identifying the optimum microbubble concentration for Echo PIV measurements in real-time. The texture features, standard deviation of gray level, and contrast, energy and homogeneity of gray level co-occurrence matrix were extracted from ultrasound contrast images of rotational and pulsatile flow (10 MHz) in vitro and in vivo mouse common carotid arterial flow (40 MHz) with UCAs at various concentrations. The results showed that, at concentration of 0.8~2 × 103 bubbles/mL in vitro and 1~5 × 105 bubbles/mL in vivo, image texture features had a peak value or trough value, and velocity vectors with high accuracy can be obtained. Otherwise, poor quality velocity vectors were obtained. When the texture features were used as a feature set, the accuracy of K-nearest neighbor classifier can reach 86.4% in vitro and 87.5% in vivo, respectively. The texture-based method is shown to be able to quickly identify the optimum microbubble concentration and improve the accuracy for Echo PIV imaging.

Niu, Lili; Qian, Ming; Yan, Liang; Yu, Wentao; Jiang, Bo; Jin, Qiaofeng; Wang, Yanping; Shandas, Robin; Liu, Xin; Zheng, Hairong



Wavelet analysis in a structured clay soil using 2-D images  

NASA Astrophysics Data System (ADS)

The spatial variability of preferential pathways for water and chemical transport in a field soil, as visualized through dye infiltration experiments, was studied by applying multifractal and wavelet transform analysis (WTA). After dye infiltration into a 4 m² plot located on a Vertisol soil near College Station, Texas, horizontal planes in the subsoil were exposed at 5 cm intervals, and dye stain patterns were photographed. Box-counting methods and WTA were applied to all of the 16 digitalized high-resolution dye images and to the dye-mass image obtained merging all sections. The well-known Devil's staircase multifractal was also used to illustrate wavelet-based analysis. Our results suggest that wavelet methods can complement box-counting analysis in the context of multiscaling structure analysis.

Piñuela, J. A.; Andina, D.; McInnes, K. J.; Tarquis, A. M.



Inflatable Icons: Diffusion-Based Interactive Extrusion of 2D Images into 3D Models  

Microsoft Academic Search

There are many applications, such as rapid prototyping, simulations and presentations, where non-professional computer end-users could benefit from the ability to create simple 3D models. Existing tools are geared towards the creation of production quality 3D models by professional users with sufficient background, time and motivation to overcome steep learning curves. Inflatable Icons combine diffusion-based image extrusion with a number

Alexander Repenning



Ignition and early soot formation in a DI diesel engine using multiple 2-D imaging diagnostics  

Microsoft Academic Search

Combined optical imaging diagnostics in the fuel jet of a direct-injection diesel engine to study the ignition and early soot formation processes. A diesel engine of the 'heavy-duty' size class was operated at a representative medium speed (1200 rpm) operating condition. Two fuels were used, a 42.5 cetane number mixture of the diesel reference fuels and a new low-sooting fuel.

John E. Dec; Christoph Espey



2-D analysis of leakage in printed-circuit lines using discrete complex-images technique  

Microsoft Academic Search

The mixed-potential integral equation is combined with the discrete complex-images technique to analyze the complete spectrum of multilayered printed transmission lines. A relevant contribution of the present two-dimensional approach is its ability to study both the bound and leaky regimes in a very simple, systematic, and efficient way. Since the analysis is carried out in the spatial domain, this method

Joaquín Bernal; Francisco Mesa; Francisco Medina



Visualizing 3D objects from 2D cross sectional images displayed in-situ versus ex-situ  

PubMed Central

The present research investigates how mental visualization of a 3D object from 2D cross sectional images is influenced by displacing the images from the source object, as is customary in medical imaging. Three experiments were conducted to assess people’s ability to integrate spatial information over a series of cross sectional images, in order to visualize an object posed in 3D space. Participants used a hand-held tool to reveal a virtual rod as a sequence of cross-sectional images, which were displayed either directly in the space of exploration (in-situ) or displaced to a remote screen (ex-situ). They manipulated a response stylus to match the virtual rod’s pitch (vertical slant), yaw (horizontal slant), or both. Consistent with the hypothesis that spatial co-location of image and source object facilitates mental visualization, we found that although single dimensions of slant were judged accurately with both displays, judging pitch and yaw simultaneously produced differences in systematic error between in-situ and ex-situ displays. Ex-situ imaging also exhibited errors such that the magnitude of the response was approximately correct but the direction was reversed. Regression analysis indicated that the in-situ judgments were primarily based on spatio-temporal visualization, while the ex-situ judgments relied on an ad hoc, screen-based heuristic. These findings suggest that in-situ displays may be useful in clinical practice by reducing error and facilitating the ability of radiologists to visualize 3D anatomy from cross sectional images.

Wu, Bing; Klatzky, Roberta L.; Stetten, George



Fast 2D-3D marker-based registration of CT and X-ray fluoroscopy images for image-guided surgery  

NASA Astrophysics Data System (ADS)

We propose a fast 2D-3D marker-based registration technique to fuse anatomical structure of 3D CT scans onto 2D X-ray fluoroscopy image. Our method is composed of three stages. First, DRRs (Digitally Reconstructed Radiography) are generated by maximum intensity projection based on hardware texture-based volume rendering. This technique is over 200 times faster than software-based one. Second, confirmation markers are automatically segmented in DRRs and X-ray fluoroscopy images, respectively. Third, in/out-plane registration is proposed for real-time performance. In out-plane registration, we search for an optimal position of X-ray source in a 3D spherical coordinate system. Then we calculate optimal translation and rotation vectors by using principal axes method in in-plane registration. Our method has been successfully six different CT and X-ray fluoroscopy pairs generated from cardiac phantom datasets. For accuracy evaluation, we calculate root-mean-squared error (RMSE) between confirmation markers of DRRs and X-ray fluoroscopy images. Experimental results show that our DRRs generation method performs very fast and the hierarchical registration effectively finds the matching of DRRs and 2D images.

Hong, Helen; Kim, Kyehyun; Park, Sungjin



A novel 2D-3D registration algorithm for aligning fluoro images with 3D pre-op CT/MR images  

NASA Astrophysics Data System (ADS)

We propose a novel and fast way to perform 2D-3D registration between available intra-operative 2D images with pre-operative 3D images in order to provide better image-guidance. The current work is a feature based registration algorithm that allows the similarity to be evaluated in a very efficient and faster manner than that of intensity based approaches. The current approach is focused on solving the problem for neuro-interventional applications and therefore we use blood vessels, and specifically their centerlines as the features for registration. The blood vessels are segmented from the 3D datasets and their centerline is extracted using a sequential topological thinning algorithm. Segmentation of the 3D datasets is straightforward because of the injection of contrast agents. For the 2D image, segmentation of the blood vessel is performed by subtracting the image with no contrast (native) from the one with a contrast injection (fill). Following this we compute a modified version of the 2D distance transform. The modified distance transform is computed such that distance is zero on the centerline and increases as we move away from the centerline. This allows us a smooth metric that is minimal at the centerline and large as we move away from the vessel. This is a one time computation, and need not be reevaluated during the iterations. Also we simply sum over all the points rather than evaluating distances over all point pairs as would be done for similar Iterative Closest Point (ICP) based approaches. We estimate the three rotational and three translational parameters by minimizing this cost over all points in the 3D centerline. The speed improvement allows us to perform the registration in under a second on current workstations and therefore provides interactive registration for the interventionalist.

Sundar, Hari; Khamene, Ali; Xu, Chenyang; Sauer, Frank; Davatzikos, Christos



Temperature, pressure and high-fidelity pointing knowledge for solar occultation using 2D focal plane arrays  

NASA Astrophysics Data System (ADS)

Accurate simultaneous retrievals of temperature and pressure are key to retrieving high quality mixing ratio profiles from occultation sensors. Equally important is accurate determination of the vertical separation between measurement points. Traditionally, these tasks are complicated by platform motion and CO2 model errors. We present a new approach that is independent of platform motion and CO2 concentration, using inexpensive modern 2D focal-plane arrays and an innovative refraction-angle measurement. This provides both accurate temperature retrievals and precise vertical separation of measurement samples, greatly improving the quality of mixing ratio retrievals. We show recent studies demonstrating the expected performance of the SOFIE instrument (Solar Occultation For Ice Experiment) to be launched as part of the AIM (Aeronomy of Ice Mission) in September 2006. This system will have the ability to retrieve accurate temperature, through mild particulate contamination (such as volcanic aerosol and cirrus) from cloud-top to stratopause, independent of mixing ratio knowledge. Additional CO2 absorption channels will provide retrieved temperature and CO2 mixing ratios through the mesosphere and into the lower thermosphere.

Gordley, Larry L.; McHugh, Martin J.; Hervig, Mark E.; Burton, John C.; Liu, Liang; Magill, Brian E.; Russell, James M.



Characterization of broadband MHD fluctuations during type-II edge localized modes as measured in 2D with ECE-imaging at ASDEX Upgrade  

NASA Astrophysics Data System (ADS)

The characterization of a broadband fluctuation that is typical for the type-II ELM regime at ASDEX Upgrade has been improved using the 2D capabilities of ECE-imaging. During the transition from the type-I to type-II ELMy phase, it has been found that electron temperature fluctuations form a broadband peak in the 19-65 kHz range. In the type-II phase, this broadband fluctuation reaches a maximum relative amplitude of almost 20% just inside the top of the pedestal. Simultaneously, the electron temperature profile is completely flattened at this location. The 2D distribution of the amplitude of this broadband fluctuation is such that, when averaged over time, a minimum occurs around the mid-plane. From the measurements of the nearby magnetic pickup coils, a similar broadband fluctuation seems visible in the same frequency range. However, this is peaked at a slightly lower frequency and does not show a similar minimum. From the analysis of the fluctuations on small timescales, the poloidal and toroidal mode numbers are estimated to be m ˜ 100 and n ˜ 21. Furthermore, activity reminiscent of beat waves has been observed, which might partially account for the fluctuation's broadband nature and the seeming velocity variation of single fluctuation passages. Overall, similarities between the characteristics of this broadband fluctuation and various precursors to type-I ELMs suggest that this fluctuation can play an important role in regulating the ELM cycle.

Boom, J. E.; Wolfrum, E.; Classen, I. G. J.; de Vries, P. C.; Maraschek, M.; Suttrop, W.; Pérez von Thun, C. P.; Donné, A. J. H.; Tobias, B. J.; Domier, C. W.; Luhmann, N. C., Jr.; Park, H. K.; the ASDEX Upgrade Team



2-D tomographic imaging of continental crust and relic slab beneath Baja California  

NASA Astrophysics Data System (ADS)

Rifting of Baja California from the margin of North America began as, or sometime before, subduction of the Farallon plate ceased (~12 Ma). Many have speculated that increased coupling between the subducted Farallon slab and overriding plate caused the young upper part of the subducted plate to detach from the older, colder, sinking slab. Then as the fragments of the Farallon plate took on Pacific plate motion, traction forces between the relic slab and Baja influenced rift localization in the Gulf of California. To better understand the processes that led to rifting of the Baja peninsula a 350 km seismic refraction/reflection profile was collected in 2002 in an effort to constrain the crustal thickness, the extent of relic slab beneath Baja California and the upper mantle P-wave velocities. The line spans the Baja Peninsula from the paleo-trench to the central Gulf of California, between the Farallon and Pescadero basins. 13 Ocean-Bottom Seismometers and 8 onshore Ref-Tek portable seismometers recorded 35,504 airgun shots from the R/V Ewing. Multichannel seismic (MCS) reflection profiles were collected on either side of the peninsula, providing information on the upper crustal structure and style of post-subduction deformation, particularly along the Tosco-Abreojos and Santa Margarita-San Lazaro fault systems. Here we present the integrated results of the MCS profiles and 2-D travel time tomography. Ray tracing was performed on 13,388 arrival picks, including Pg, Pn and PmP arrivals. Initial tomographic inversions reveal a crustal root beneath Baja California with an average velocity of 6.0 km/s. Continental crust thins to the east into the Gulf of California and has a velocity structure consistent with that of the Alarcon segment of the PESCADOR experiment. Perhaps the most significant observation is an ~6 km thick, 8° east-dipping high velocity zone (mean of 6.7 km/s) that underplates the western Baja margin and extends at least 60 km from the former trench (~40 km west of the shoreline). We interpret this to be relic oceanic crust. We are investigating the extent of the relic slab beneath Baja and its relationship with high-Mg adakitic volcanics exposed on Isla Margarita, ~20 km north of the seismic transect. The existence of a stalled slab beneath the Baja margin suggests frictional and/or viscous coupling along the paleo-subduction interface is an important process in for the geodynamical development of the Gulf of California rift system.

Brothers, D. S.; Harding, A. J.; Kent, G.; Driscoll, N.



Visualization of aerocolloidal biological particles using 2D particle image velocimetry (PIV)  

NASA Astrophysics Data System (ADS)

Recent concerns over the possible use of airborne biological particles as weapons of mass destruction have significantly increased the attention that researchers are giving to this threat. The size of these particles, ranging from a fraction of a micrometer to several tens of micrometers, allows them to travel over long distances before settling out of the airstreams carrying these particles. Furthermore, the odd shapes of many of these particles along with uncertainties about their light scattering characteristics make detection and tracking quite a challenge. In the present paper, results are reported on the visualization of airborne biological particles using two-dimensional particle image velocimetry (PIV). These initial results show the utility of PIV in illuminating and tracking airborne biological particles. A compressed air nebulizer is used to aerosolize the biological particles inside a Plexiglas test section. The biological particles prepared for the nebulizer are first inoculated and cultured onto agar media, gypsum board, and acoustic ceiling tile to achieve an abundant growth of spores. A colloidal suspension of biological particles is then made using sterilized, de-ionized water and a mild surfactant to de-agglomerate the biological particles in the suspension. The concentration of biological particles in the colloidal suspension is determined using a hemacytometer. In the visualization experiments, images are captured for polystyrene latex (PSL) test particles, liquid water droplets, and spores of the fungal species Aspergillus versicolor. During the PIV system operation, two successive images are captured with a time delay of 50 ?m to develop flow field velocities of the PSL test particles, liquid water droplets, and the A. versicolor spores.

Hall, Carsie A., III; Masabattula, Sree; Akyuzlu, Kazim M.; Russo, Edwin P.; Klich, Maren A.



Tangential 2-D Edge Imaging for GPI and Edge/Impurity Modeling  

SciTech Connect

Nova Photonics, Inc. has a collaborative effort at the National Spherical Torus Experiment (NSTX). This collaboration, based on fast imaging of visible phenomena, has provided key insights on edge turbulence, intermittency, and edge phenomena such as edge localized modes (ELMs) and multi-faceted axisymmetric radiation from the edge (MARFE). Studies have been performed in all these areas. The edge turbulence/intermittency studies make use of the Gas Puff Imaging diagnostic developed by the Principal Investigator (Ricardo Maqueda) together with colleagues from PPPL. This effort is part of the International Tokamak Physics Activity (ITPA) edge, scrape-off layer and divertor group joint activity (DSOL-15: Inter-machine comparison of blob characteristics). The edge turbulence/blob study has been extended from the current location near the midplane of the device to the lower divertor region of NSTX. The goal of this effort was to study turbulence born blobs in the vicinity of the X-point region and their circuit closure on divertor sheaths or high density regions in the divertor. In the area of ELMs and MARFEs we have studied and characterized the mode structure and evolution of the ELM types observed in NSTX, as well as the study of the observed interaction between MARFEs and ELMs. This interaction could have substantial implications for future devices where radiative divertor regions are required to maintain detachment from the divertor plasma facing components.

Dr. Ricardo Maqueda; Dr. Fred M. Levinton



Automatic multimodal 2D/3D breast image registration using biomechanical FEM models and intensity-based optimization.  


Due to their different physical origin, X-ray mammography and Magnetic Resonance Imaging (MRI) provide complementary diagnostic information. However, the correlation of their images is challenging due to differences in dimensionality, patient positioning and compression state of the breast. Our automated registration takes over part of the correlation task. The registration method is based on a biomechanical finite element model, which is used to simulate mammographic compression. The deformed MRI volume can be compared directly with the corresponding mammogram. The registration accuracy is determined by a number of patient-specific parameters. We optimize these parameters--e.g. breast rotation--using image similarity measures. The method was evaluated on 79 datasets from clinical routine. The mean target registration error was 13.2mm in a fully automated setting. On basis of our results, we conclude that a completely automated registration of volume images with 2D mammograms is feasible. The registration accuracy is within the clinically relevant range and thus beneficial for multimodal diagnosis. PMID:23265802

Hopp, T; Dietzel, M; Baltzer, P A; Kreisel, P; Kaiser, W A; Gemmeke, H; Ruiter, N V



New generation CMOS 2D imager evaluation and qualification for semiconductor inspection applications  

NASA Astrophysics Data System (ADS)

Semiconductor fabrication process defect inspection industry is always driven by inspection resolution and through-put. With fabrication technology node advances to 2X ~1Xnm range, critical macro defect size approaches to typical CMOS camera pixel size range, therefore single pixel defect detection technology becomes more and more essential, which is fundamentally constrained by camera performance. A new evaluation model is presented here to specifically describe the camera performance for semiconductor machine vision applications, especially targeting at low image contrast high speed applications. Current mainline cameras and high-end OEM cameras are evaluated with this model. Camera performances are clearly differentiated among CMOS technology generations and vendors, which will facilitate application driven camera selection and operation optimization. The new challenges for CMOS detectors are discussed for semiconductor inspection applications.

Zhou, Wei; Hart, Darcy



A temperature dependent 2D-ACAR study of untwinned metallic YBa{sub 2}Cu{sub 3}O{sub 7{minus}x}  

SciTech Connect

The authors have carried out 2D-ACAR measurements in the c-axis projection on an untwinned single crystal of YBa{sub 2}Cu{sub 3}O{sub 7{minus}x} as a function of temperature, for five temperatures ranging from 30K to 300K. These temperature dependent 2D-ACAR spectra can be approximated by a superposition of two temperature independent spectra with temperature dependent weighting factors. The authors discuss how the temperature dependence of the data can be exploited to obtain a {open_quote}background corrected{close_quote} experimental spectrum, which is found to be in remarkable accord with the corresponding band theory based predictions, including for the first time the overall amplitude of the anisotropy in the 2D-ACAR. The corrected data also show clear signatures of the ridge Fermi surface and an indication of the pillbox surface.

Smedskjaer, L.C.; Welp, U.; Fang, Y.; Bailey, K.G. [Argonne National Lab., IL (United States); Bansil, A. [Northeastern Univ., Boston, MA (United States)



A 256 x 256 2-D array transducer with row-column addressing for 3-D rectilinear imaging.  


We present simulation and experimental results from a 5-MHz, 256 x 256 2-D (65,536 elements, 38.4 x 38.4 mm) 2-D array transducer with row-column addressing. The main benefits of this design are a reduced number of interconnects, a modified transmit/receive switching scheme with a simple diode circuit, and an ability to perform volumetric imaging of targets near the transducer with transmit beamforming in azimuth and receive beamforming in elevation. The final dimensions of the transducer were 38.4 mm x 38.4 mm x 300 microm. After a row-column transducer was prototyped, the series resonance impedance was 104 Omega at 5.4 MHz. The measured -6 dB fractional bandwidth was 53% with a center frequency of 5.3 MHz. The SNR at the transmit focus was measured to be 30 dB. At 5 MHz, the average nearest neighbor crosstalk was -25 dB. In this paper, we present 3-D images of both 5 pairs of nylon wires embedded in a clear gelatin phantom and an 8 mm diameter cylindrical anechoic cyst phantom acquired from a 256 x 256 2-D array transducer made from a 1-3 composite. We display the azimuth and elevation B-scans as well as the C-scan for each image. The cross-section of the wires is visible in the azimuth B-scan, and the long axes can be seen in the elevation B-scan and C-scans. The pair of wires with 1-mm axial separation is discernible in the elevational B-scan. When a single wire from the wire target phantom was used, the measured lateral beamwidth was 0.68 mm and 0.70 mm at 30 mm depth in transmit beamforming and receive beamforming, respectively, compared with the simulated beamwidth of 0.55 mm. The cross-section of the cyst is visible in the azimuth B-scan whereas the long axes can be seen as a rectangle in the elevation B-scan and C-scans. PMID:19406713

Seo, Chi Hyung; Yen, Jesse T



MIA-QSAR: a simple 2D image-based approach for quantitative structure activity relationship analysis  

NASA Astrophysics Data System (ADS)

An accessible and quite simple QSAR method, based on 2D image analysis, is reported. A case study is carried out in order to compare this model with a previously reported sophisticated methodology. A well known set of (S)-N-[(1-ethyl-2-pyrrolidinyl)methyl]-6-methoxybenzamides, compounds with affinity to the dopamine D2 receptor subtype, was divided in 40 calibration compounds and 18 test compounds and the descriptors were generated from pixels of 2D structures of each compound, which can be drawn with aid of any appropriate program. Bilinear (conventional) PLS was utilized as the regression method and leave-one-out cross-validation was performed using the NIPALS algorithm. The good predicted Q2 value obtained for the series of test compounds (0.58), together with the similar prediction quality obtained to other data sets (nAChR ligands, HIV protease inhibitors, COX-2 inhibitors and anxiolytic agents), suggests that the model is robust and seems to be as applicable as more complex methods.

Freitas, Matheus P.; Brown, Steven D.; Martins, José A.



Assessment of normal testis growth by quantitative texture analysis of 2-D echo images.  


Six phases summarize the evolution of the healthy male gonad. Qualitative examination of two-dimensional echograms detects tonal differences at different ages of the testes. However, routine qualitative evaluation of the echograms is too subjective and dependent upon the scanner controls; on the other hand, simple morphology reports are not sufficient to establish the correct histologic and physiologic evolution. So far computer-assisted quantitative analysis of ultrasonic images has been successful in the characterization of tissues based on their echographic properties; thus this approach could be suitable for an accurate identification of the age of healthy testis. Sixty-two normal subjects, ranked in six groups according to age, underwent echographic examination in standard conditions. Echograms were digitized and analysed by means of well-established algorithms for first and second order statistics. Significant differences in tonal features were found able to discriminate among different ages, in agreement with the qualitative analysis and the histologic reports. Furthermore, some second order analysis features exhibit statistically significant alterations of the micro-structural organisation of the echo patterns consequent to changes of the configuration of the ultrasonic targets, that is, of the gonad's histology. In conclusion, quantitative analysis of echograms can provide a tool for a better assessment of normal testis evolution than the qualitative approach. PMID:7489125

Ferdeghini, E M; Morelli, G; Distante, A; Giannotti, P; Benassi, A



Enhancing LTW image encoder with perceptual coding and GPU-optimized 2D-DWT transform  

NASA Astrophysics Data System (ADS)

When optimizing a wavelet image coder, the two main targets are to (1) improve its rate-distortion (R/D) performance and (2) reduce the coding times. In general, the encoding engine is mainly responsible for achieving R/D performance. It is usually more complex than the decoding part. A large number of works about R/D or complexity optimizations can be found, but only a few tackle the problem of increasing R/D performance while reducing the computational cost at the same time, like Kakadu, an optimized version of JPEG2000. In this work we propose an optimization of the E_LTW encoder with the aim to increase its R/D performance through perceptual encoding techniques and reduce the encoding time by means of a graphics processing unit-optimized version of the two-dimensional discrete wavelet transform. The results show that in both performance dimensions, our enhanced encoder achieves good results compared with Kakadu and SPIHT encoders, achieving speedups of 6 times with respect to the original E_LTW encoder.

Martínez-Rach, Miguel O.; López-Granado, Otoniel; Galiano, Vicente; Migallón, Hector; Llor, Jesús; Malumbres, Manuel P.



Evaluation of 2D and 3D images using eye movement, head movement, and body sway  

NASA Astrophysics Data System (ADS)

The induced motion from visual information is discussed in showing the stable and moving images with or without disparities. Experiments were conducted to measure body sway, eye movement, and head movement under plane depth visual stimuli, to clarify the effect caused by the depth information for induced motion. Several obvious points emerged from the analysis of the experimental data. The minimal visual area needed to make the body stale is about 45 degrees for the plane stimuli, and is about 22.5 degrees of 45 degrees for the depth stimuli. It was also found that there are large differences in body sway between the plane stimuli and the depth stimuli after target moving. For the moving visual stimuli without disparity, the body sway was found to depend on the visual angle, but in the other case, it was found to be independent of the visual angle. This is due to the difference in OKN values from the measurement of eye movement. The frequency of emergence and the amplitude of OKN in the depth stimuli were larger than those of OKN in the plane stimuli. It was additionally observed that the low-frequency components of body sway were equal to those of head movement in these experiments.

Ojima, Shuichi; Yano, Sumio



Parameters Affecting the Resolution and Accuracy of 2D Quantitative Shear Wave Images  

PubMed Central

Time-of-flight methods allow quantitative measurement of shear wave speed (SWS) from ultra-sonically tracked displacements following impulsive, acoustic radiation force excitation in tissue. In heterogeneous materials, reflections at boundaries can distort the wave shape and confound determination of the wave arrival time. The magnitude of these effects depends on the shear wavelength of the excitation, the kernel size used to calculate the SWS, and the method used to determine the wave arrival time. In this study, we perform a parametric analysis of these factors using finite element modeling of the tissue response, and simulated ultrasonic tracking. Two geometries are used, a stiff, vertical layer, and a stiff spherical inclusion, each in a uniform background. Wave arrival times are estimated using the peak displacement, peak slope of the leading edge, and cross correlation methods. Results are evaluated in terms of reconstruction accuracy, resolution, contrast, and contrast-to-noise ratio of reconstructed SWS images. Superior results are obtained using narrower excitation widths and arrival time estimators which identify the leading edge of the propagating wave. The optimal kernel size is determined by a tradeoff between improved accuracy for larger kernels at the expense of spatial resolution.

Rouze, Ned C.; Wang, Michael H.; Palmeri, Mark L.; Nightingale, Kathryn R.



Segmentation of skin lesions in 2-D and 3-D ultrasound images using a spatially coherent generalized Rayleigh mixture model.  


This paper addresses the problem of jointly estimating the statistical distribution and segmenting lesions in multiple-tissue high-frequency skin ultrasound images. The distribution of multiple-tissue images is modeled as a spatially coherent finite mixture of heavy-tailed Rayleigh distributions. Spatial coherence inherent to biological tissues is modeled by enforcing local dependence between the mixture components. An original Bayesian algorithm combined with a Markov chain Monte Carlo method is then proposed to jointly estimate the mixture parameters and a label-vector associating each voxel to a tissue. More precisely, a hybrid Metropolis-within-Gibbs sampler is used to draw samples that are asymptotically distributed according to the posterior distribution of the Bayesian model. The Bayesian estimators of the model parameters are then computed from the generated samples. Simulation results are conducted on synthetic data to illustrate the performance of the proposed estimation strategy. The method is then successfully applied to the segmentation of in vivo skin tumors in high-frequency 2-D and 3-D ultrasound images. PMID:22434797

Pereyra, Marcelo; Dobigeon, Nicolas; Batatia, Hadj; Tourneret, Jean-Yves



2D Soft X-ray System for Imaging Magnetic Topology in the Pedestal Region on DIII-D  

NASA Astrophysics Data System (ADS)

A new tangential 2D Soft X-ray Imaging System (SXRIS) is designed to examine the edge magnetic island structure in the lower X-point region of DIII-D. Plasma shielding and/or amplification of applied resonant magnetic perturbations (RMPs) may play a role in the suppression of edge localized modes. The SXRIS will aid in determining the 3D magnetic structure due to applied RMPs. A synthetic diagnostic calculation based on 3D SXRIS emissivity estimates calibrated against NSTX data, shows a signal-to-noise ratio of 10 with 1 cm resolution for a 25 ms integration time. Impurity puffing is expected to increase the SNR further. Image inversion is required but is an ill-posed problem, requiring symmetry assumptions such as constant emission along field lines. Advanced inversion methods are examined in the context of noise, spatial sensitivity, and symmetry assumptions. Forward modeling is used to compare 3D equilibria, e.g. from SIESTA, and simulated images to examine the non-ideal plasma response.

Shafer, M. W.; Battaglia, D. J.; Unterberg, E. A.; Canik, J.; Hillis, D. L.; Maingi, R.; Evans, T. E.



2D and 3D soil moisture imaging using a sensor-based platform moving inside a subsurface network of pipes  

NASA Astrophysics Data System (ADS)

A new soil moisture tomography system is presented.A sensor-based platform moves through a subsurface piping system and monitors soil moisture content.Image processing software allows the creation of 2D and 3D soil moisture images.The images show spatial and temporal soil moisture variability in the meter-scale.Soil moisture imaging is very useful for precise crop irrigation management.

Gravalos, I.; Moshou, D.; Loutridis, S.; Gialamas, Th.; Kateris, D.; Bompolas, E.; Tsiropoulos, Z.; Xyradakis, P.; Fountas, S.



Finger, sex, and side differences in fingertip size and lack of association with image-based digit ratio (2D:4D) measurements.  


Different methods for measuring the second-to-fourth digit ratio (2D:4D), a putative marker for prenatal androgen exposure, may lead to varying values of 2D:4D. Specifically, it has been hypothesized that fingertip fat pads may be differentially deformed when taking palm images (photocopies or flatbed scans), but not when fingers are measured directly, thus yielding lower 2D:4D values from image-based measurements rather than direct ones. A measurement protocol for fingertip size is unavailable, as are data on finger and sex differences in this trait. Introducing such a protocol, this study found very large finger differences in adult fingertip size (largest for 4D, smaller for 3D and 5D, smallest for 2D), large side differences (larger in the left than in the right hand of right-handed subjects), but only small and not significant sex differences. Fingertip size was unrelated to image-based 2D:4D measurements, suggesting that fingertip size and the extent of finger and sex differences therein are unlikely to explain discrepant 2D:4D values obtained from image-based versus direct measurements. PMID:19093612

Voracek, Martin; Pietschnig, Jakob; Oeckher, Michael



2D/3D image fusion of x-ray mammograms with speed of sound images: evaluation and visualization  

NASA Astrophysics Data System (ADS)

Breast cancer is the most common cancer among women. The established screening method to detect breast cancer is X-ray mammography. However, X-ray frequently provides poor contrast of tumors located within glandular tissue. In this case, additional modalities like MRI are used for diagnosis in clinical routine. A new imaging approach is Ultrasound Computer Tomography, generating three-dimensional speed of sound images. High speed of sound values are expected to be an indicator of cancerous structures. Therefore, the combination of speed of sound images and X-ray mammograms may benefit early breast cancer diagnosis. In previous work, we proposed a method based on Finite Elements to automatically register speed of sound images with the according mammograms. The FEM simulation overcomes the challenge that X-ray mammograms show two-dimensional projections of a deformed breast whereas speed of sound images render a three-dimensional undeformed breast in prone position. In this work, 15 datasets from a clinical study were used for further evaluation of the registration quality. The quality of the registration was measured by the displacement of the center of a lesion marked in both modalities. We found a mean displacement of 7.1 mm. For visualization, an overlay technique was developed, which displays speed of sound information directly on the mammogram. Hence, the methodology provides a good basis for multimodal diagnosis using mammograms and speed of sound images. It proposes a guidance tool for radiologists who may benefit from the combined information.

Hopp, Torsten; Bonn, Julie; Ruiter, Nicole V.; Sak, Mark; Duric, Neb



Motion-compensated mega-voltage cone beam CT using the deformation derived directly from 2D projection images.  


This paper presents a novel method for respiratory motion compensated reconstruction for cone beam computed tomography (CBCT). The reconstruction is based on a time sequence of motion vector fields, which is generated by a dynamic geometrical object shape model. The dynamic model is extracted from the 2D projection images of the CBCT. The process of the motion extraction is converted into an optimal 3D multiple interrelated surface detection problem, which can be solved by computing a maximum flow in a 4D directed graph. The method was tested on 12 mega-voltage (MV) CBCT scans from three patients. Two sets of motion-artifact-free 3D volumes, full exhale (FE) and full inhale (FI) phases, were reconstructed for each daily scan. The reconstruction was compared with three other motion-compensated approaches based on quantification accuracy of motion and size. Contrast-to-noise ratio (CNR) was also quantified for image quality. The proposed approach has the best overall performance, with a relative tumor volume quantification error of 3.39 ± 3.64% and 8.57 ± 8.31% for FE and FI phases, respectively. The CNR near the tumor area is 3.85 ± 0.42 (FE) and 3.58 ± 3.33 (FI). These results show the clinical feasibility to use the proposed method to reconstruct motion-artifact-free MVCBCT volumes. PMID:23247845

Chen, Mingqing; Cao, Kunlin; Zheng, Yefeng; Siochi, R Alfredo C



Clinical Study of 2D and 3D Scan Time Reduction in Head \\/ Neck Cancer with BGO Based PET \\/ CT using Statistical Image Analysis  

Microsoft Academic Search

The advantages of two-dimensional (2D) compared with three-dimensional (3D) imaging and reducing scan time in BGO based Positron Emission Tomography\\/Computed Tomography (PET\\/CT) scanners remains a matter of discussion. We investigate these parameters for an axial single-field-of view (SFOV) in head and neck cancer using an interleaved 2D and 3D protocol. Each scan pair consists of 4 min, 3 min and

B. Sanghera; J. Lowe; G. Lowe; D. Wellstead; H. Bammer; R. J. Chambers; W. L. Wong



Imaging 2D structures by the CSAMT method: application to the Pantano di S. Gregorio Magno faulted basin (Southern Italy)  

NASA Astrophysics Data System (ADS)

A controlled source audiofrequency magnetotelluric (CSAMT) survey has been undertaken in the Pantano di San Gregorio Magno faulted basin, an earthquake prone area of Southern Apennines in Italy. A dataset from 11 soundings, distributed along a nearly N-S 780 m long profile, was acquired in the basin's easternmost area, where the fewest data are available as to the faulting shallow features. A preliminary skew analysis allowed a prevailing 2D nature of the dataset to be ascertained. Then, using a single-site multi-frequency approach, Dantzig's simplex algorithm was introduced for the first time to estimate the CSAMT decomposition parameters. The simplex algorithm, freely available online, proved to be fast and efficient. By this approach, the TM and TE mode field diagrams were obtained and a N35°W ± 10° 2D strike mean direction was estimated along the profile, in substantial agreement with the fault traces within the basin. A 2D inversion of the apparent resistivity and phase curves at seven almost noise-free sites distributed along the central portion of the profile was finally elaborated, reinforced by a sensitivity analysis, which allowed the best resolved portion of the model to be imaged from the first few meters of depth down to a mean depth of 300 m b.g.l. From the inverted section, the following features have been outlined: (i) a cover layer with resistivity in the range 3-30 ? m ascribed to the Quaternary lacustrine clayey deposits filling the basin, down to an average depth of about 35 m b.g.l., underlain by a structure with resistivity over 50 ? m up to about 600 ? m, ascribed to the Mesozoic carbonate bedrock; (ii) a system of two normal faults within the carbonate basement, extending down to the maximum best resolved depth of the order of 300 m b.g.l.; (iii) two wedge-shaped domains separating the opposite blocks of the faults with resistivity ranging between 30 ? m and 50 ? m and horizontal extent of the order of some tens of metres, likely filled with lacustrine sediments and embedded fine gravels.

Troiano, Antonio; Di Giuseppe, Maria Giulia; Petrillo, Zaccaria; Patella, Domenico



A Novel Assessment of Various Bio-Imaging Methods for Lung Tumor Detection and Treatment by using 4-D and 2-D CT Images  

PubMed Central

Lung Cancer is known as one of the most difficult cancer to cure, and the number of deaths that it causes generally increasing. A detection of the Lung Cancer in its early stage can be helpful for Medical treatment to limit the danger, but it is a challenging problem due to Cancer cell structure. Interpretation of Medical image is often difficult and time consuming, even for the experienced Physicians. The aid of image analysis Based on machine learning can make this process easier. This paper describes fully Automatic Decision Support system for Lung Cancer diagnostic from CT Lung images. Most traditional medical diagnosis systems are founded on huge quantity of training data and takes long processing time. However, on the occasion that very little volume of data is available, the traditional diagnosis systems derive defects such as larger error, Time complexity. Focused on the solution to this problem, a Medical Diagnosis System based on Hidden Markov Model (HMM) is presented. In this paper we describe a pre-processing stage involving some Noise removal techniques help to solve this problem, we preprocess an images (by Mean Error Square Filtering and Histogram analysis)obtained after scanning the Lung CT images. Secondly separate the lung areas from an image by a segmentation process (by Thresholding and region growing techniques). Finally we developed HMM for the classification of Cancer Nodule. Results are checked for 2D and 4D CT images. This automation process reduces the time complexity and increases the diagnosis confidence.

Judice A., Antony; Geetha, Dr. K. Parimala



Individual Recognition in Domestic Cattle (Bos taurus): Evidence from 2D-Images of Heads from Different Breeds  

PubMed Central

Background In order to maintain cohesion of groups, social animals need to process social information efficiently. Visual individual recognition, which is distinguished from mere visual discrimination, has been studied in only few mammalian species. In addition, most previous studies used either a small number of subjects or a few various views as test stimuli. Dairy cattle, as a domestic species allow the testing of a good sample size and provide a large variety of test stimuli due to the morphological diversity of breeds. Hence cattle are a suitable model for studying individual visual recognition. This study demonstrates that cattle display visual individual recognition and shows the effect of both familiarity and coat diversity in discrimination. Methodology/Principal Findings We tested whether 8 Prim'Holstein heifers could recognize 2D-images of heads of one cow (face, profiles, ¾ views) from those of other cows. Experiments were based on a simultaneous discrimination paradigm through instrumental conditioning using food rewards. In Experiment 1, all images represented familiar cows (belonging to the same social group) from the Prim'Holstein breed. In Experiments 2, 3 and 4, images were from unfamiliar (unknown) individuals either from the same breed or other breeds. All heifers displayed individual recognition of familiar and unfamiliar individuals from their own breed. Subjects reached criterion sooner when recognizing a familiar individual than when recognizing an unfamiliar one (Exp 1: 3.1±0.7 vs. Exp 2: 5.2±1.2 sessions; Z?=?1.99, N?=?8, P?=?0.046). In addition almost all subjects recognized unknown individuals from different breeds, however with greater difficulty. Conclusions/Significance Our results demonstrated that cattle have efficient individual recognition based on categorization capacities. Social familiarity improved their performance. The recognition of individuals with very different coat characteristics from the subjects was the most difficult task. These results call for studies exploring the mechanisms involved in face recognition allowing interspecies comparisons, including humans.

Coulon, Marjorie; Deputte, Bertrand L.; Heyman, Yvan; Baudoin, Claude



Simulating Dynamic Stall in a 2D VAWT: Modeling strategy, verification and validation with Particle Image Velocimetry data  

NASA Astrophysics Data System (ADS)

The implementation of wind energy conversion systems in the built environment renewed the interest and the research on Vertical Axis Wind Turbines (VAWT), which in this application present several advantages over Horizontal Axis Wind Turbines (HAWT). The VAWT has an inherent unsteady aerodynamic behavior due to the variation of angle of attack with the angle of rotation, perceived velocity and consequentially Reynolds number. The phenomenon of dynamic stall is then an intrinsic effect of the operation of a Vertical Axis Wind Turbine at low tip speed ratios, having a significant impact in both loads and power. The complexity of the unsteady aerodynamics of the VAWT makes it extremely attractive to be analyzed using Computational Fluid Dynamics (CFD) models, where an approximation of the continuity and momentum equations of the Navier-Stokes equations set is solved. The complexity of the problem and the need for new design approaches for VAWT for the built environment has driven the authors of this work to focus the research of CFD modeling of VAWT on: •comparing the results between commonly used turbulence models: URANS (Spalart-Allmaras and k-epsilon) and large eddy models (Large Eddy Simulation and Detached Eddy Simulation) •verifying the sensitivity of the model to its grid refinement (space and time), •evaluating the suitability of using Particle Image Velocimetry (PIV) experimental data for model validation. The 2D model created represents the middle section of a single bladed VAWT with infinite aspect ratio. The model simulates the experimental work of flow field measurement using Particle Image Velocimetry by Simão Ferreira et al for a single bladed VAWT. The results show the suitability of the PIV data for the validation of the model, the need for accurate simulation of the large eddies and the sensitivity of the model to grid refinement.

Simão Ferreira, C. J.; Bijl, H.; van Bussel, G.; van Kuik, G.



Effects of x-ray and CT image enhancements on the robustness and accuracy of a rigid 3D/2D image registration  

SciTech Connect

A rigid body three-dimensional/two-dimensional (3D/2D) registration method has been implemented using mutual information, gradient ascent, and 3D texturemap-based digitally reconstructed radiographs. Nine combinations of commonly used x-ray and computed tomography (CT) image enhancement methods, including window leveling, histogram equalization, and adaptive histogram equalization, were examined to assess their effects on accuracy and robustness of the registration method. From a set of experiments using an anthropomorphic chest phantom, we were able to draw several conclusions. First, the CT and x-ray preprocessing combination with the widest attraction range was the one that linearly stretched the histograms onto the entire display range on both CT and x-ray images. The average attraction ranges of this combination were 71.3 mm and 61.3 deg in the translation and rotation dimensions, respectively, and the average errors were 0.12 deg and 0.47 mm. Second, the combination of the CT image with tissue and bone information and the x-ray images with adaptive histogram equalization also showed subvoxel accuracy, especially the best in the translation dimensions. However, its attraction ranges were the smallest among the examined combinations (on average 36 mm and 19 deg). Last the bone-only information on the CT image did not show convergency property to the correct registration.

Kim, Jinkoo; Yin Fangfang; Zhao Yang; Kim, Jae Ho [Department of Radiation Oncology, 2799 W. Grand Boulevard, Henry Ford Health System, Detroit, Michigan 48202 (United States); Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina 27710 (United States); Department of Electrical and Computer Engineering, Wayne State University, Detroit, Michigan 48202 (United States); Department of Radiation Oncology, 2799 W. Grand Boulevard, Henry Ford Health System, Detroit, Michigan 48202 (United States)



Effects of x-ray and CT image enhancements on the robustness and accuracy of a rigid 3D/2D image registration.  


A rigid body three-dimensional/two-dimensional (3D/2D) registration method has been implemented using mutual information, gradient ascent, and 3D texturemap-based digitally reconstructed radiographs. Nine combinations of commonly used x-ray and computed tomography (CT) image enhancement methods, including window leveling, histogram equalization, and adaptive histogram equalization, were examined to assess their effects on accuracy and robustness of the registration method. From a set of experiments using an anthropomorphic chest phantom, we were able to draw several conclusions. First, the CT and x-ray preprocessing combination with the widest attraction range was the one that linearly stretched the histograms onto the entire display range on both CT and x-ray images. The average attraction ranges of this combination were 71.3 mm and 61.3 deg in the translation and rotation dimensions, respectively, and the average errors were 0.12 deg and 0.47 mm. Second, the combination of the CT image with tissue and bone information and the x-ray images with adaptive histogram equalization also showed subvoxel accuracy, especially the best in the translation dimensions. However, its attraction ranges were the smallest among the examined combinations (on average 36 mm and 19 deg). Last the bone-only information on the CT image did not show convergency property to the correct registration. PMID:15895569

Kim, Jinkoo; Yin, Fang-Fang; Zhao, Yang; Kim, Jae Ho



Real-time 2D/3D registration using kV-MV image pairs for tumor motion tracking in image guided radiotherapy.  


Abstract Intra-fractional respiratory motion during radiotherapy leads to a larger planning target volume (PTV). Real-time tumor motion tracking by two-dimensional (2D)/3D registration using on-board kilo-voltage (kV) imaging can allow for a reduction of the PTV though motion along the imaging beam axis cannot be resolved using only one projection image. We present a retrospective patient study investigating the impact of paired portal mega-voltage (MV) and kV images on registration accuracy. Material and methods. We used data from 10 patients suffering from non-small cell lung cancer (NSCLC) undergoing stereotactic body radiation therapy (SBRT) lung treatment. For each patient we acquired a planning computed tomography (CT) and sequences of kV and MV images during treatment. We compared the accuracy of motion tracking in six degrees-of-freedom (DOF) using the anterior-posterior (AP) kV sequence or the sequence of kV-MV image pairs. Results. Motion along cranial-caudal direction could accurately be extracted when using only the kV sequence but in AP direction we obtained large errors. When using kV-MV pairs, the average error was reduced from 2.9 mm to 1.5 mm and the motion along AP was successfully extracted. Mean registration time was 188 ms. Conclusion. Our evaluation shows that using kV-MV image pairs leads to improved motion extraction in six DOF and is suitable for real-time tumor motion tracking with a conventional LINAC. PMID:23879647

Furtado, Hugo; Steiner, Elisabeth; Stock, Markus; Georg, Dietmar; Birkfellner, Wolfgang



Faraday imaging at high temperatures  


A Faraday filter rejects background light from self-luminous thermal objects, but transmits laser light at the passband wavelength, thus providing an ultra-narrow optical bandpass filter. The filter preserves images so a camera looking through a Faraday filter at a hot target illuminated by a laser will not see the thermal radiation but will see the laser radiation. Faraday filters are useful for monitoring or inspecting the uranium separator chamber in an atomic vapor laser isotope separation process. Other uses include viewing welds, furnaces, plasma jets, combustion chambers, and other high temperature objects. These filters are can be produced at many discrete wavelengths. A Faraday filter consists of a pair of crossed polarizers on either side of a heated vapor cell mounted inside a solenoid. 3 figs.

Hackel, L.A.; Reichert, P.



Observations of pores and aggregates during aggregation in some clay-rich agricultural soils as seen in 2D image analysis  

Microsoft Academic Search

Observations by 2D image analysis on four clay-rich agricultural soils in laboratory wetting and drying experiments indicate that the aggregation process changes the size distributions of soil materials in producing more irregular, larger particles which form through the accumulation of both small and large particles. The effect is more important with depth in laboratory and field samples. The distribution pattern

Decheng Li; B Velde; Taolin Zhang



Region and volume dependencies in spectral line width assessed by 1 H 2D MR chemical shift imaging in the monkey brain at 7 T  

Microsoft Academic Search

High magnetic fields increase the sensitivity and spectral dispersion in magnetic resonance spectroscopy (MRS). In contrast, spectral peaks are broadened in vivo at higher field strength due to stronger susceptibility-induced effects. Strategies to minimize the spectral line width are therefore of critical importance. In the present study, 1H 2D chemical shift imaging at short echo times was performed in the

Christoph Juchem; Hellmut Merkle; Fritz Schick; Nikos K. Logothetis; Josef Pfeuffer


Design and fabrication of digital 2D fringe patterns and their application to accurate integration of segmented 3D image data  

NASA Astrophysics Data System (ADS)

Fabrication of digital sinusoidal gratings for accurate integration of segmented 3D image data is presented. The main advantages of using digital 2-D fringe patterns for our proposed data fusion scheme include (1) high matching accuracy, (2) improved robustness, (3) reduced computational time, and (4) capability of compensating distortions of the optical system at every pixel location.

Su, Wei-Hung; Liu, Hongyu; Chen, Hung-Ming; Kuo, Cho-Yo; Hsu, Yi-Ling



Automatic localization of target vertebrae in spine surgery using fast CT-to-fluoroscopy (3D-2D) image registration  

NASA Astrophysics Data System (ADS)

Localization of target vertebrae is an essential step in minimally invasive spine surgery, with conventional methods relying on "level counting" - i.e., manual counting of vertebrae under fluoroscopy starting from readily identifiable anatomy (e.g., the sacrum). The approach requires an undesirable level of radiation, time, and is prone to counting errors due to the similar appearance of vertebrae in projection images; wrong-level surgery occurs in 1 of every ~3000 cases. This paper proposes a method to automatically localize target vertebrae in x-ray projections using 3D-2D registration between preoperative CT (in which vertebrae are preoperatively labeled) and intraoperative fluoroscopy. The registration uses an intensity-based approach with a gradient-based similarity metric and the CMA-ES algorithm for optimization. Digitally reconstructed radiographs (DRRs) and a robust similarity metric are computed on GPU to accelerate the process. Evaluation in clinical CT data included 5,000 PA and LAT projections randomly perturbed to simulate human variability in setup of mobile intraoperative C-arm. The method demonstrated 100% success for PA view (projection error: 0.42mm) and 99.8% success for LAT view (projection error: 0.37mm). Initial implementation on GPU provided automatic target localization within about 3 sec, with further improvement underway via multi-GPU. The ability to automatically label vertebrae in fluoroscopy promises to streamline surgical workflow, improve patient safety, and reduce wrong-site surgeries, especially in large patients for whom manual methods are time consuming and error prone.

Otake, Y.; Schafer, S.; Stayman, J. W.; Zbijewski, W.; Kleinszig, G.; Graumann, R.; Khanna, A. J.; Siewerdsen, J. H.



Computer-aided 2D and 3D quantification of human stem cell fate from in vitro samples using Volocity high performance image analysis software.  


Accurate automated cell fate analysis of immunostained human stem cells from 2- and 3-dimensional (2D-3D) images would improve efficiency in the field of stem cell research. Development of an accurate and precise tool that reduces variability and the time needed for human stem cell fate analysis will improve productivity and interpretability of the data across research groups. In this study, we have created protocols for high performance image analysis software Volocity® to classify and quantify cytoplasmic and nuclear cell fate markers from 2D-3D images of human neural stem cells after in vitro differentiation. To enhance 3D image capture efficiency, we optimized the image acquisition settings of an Olympus FV10i® confocal laser scanning microscope to match our quantification protocols and improve cell fate classification. The methods developed in this study will allow for a more time efficient and accurate software based, operator validated, stem cell fate classification and quantification from 2D and 3D images, and yield the highest ?94.4% correspondence with human recognized objects. PMID:21775237

Piltti, Katja M; Haus, Daniel L; Do, Eileen; Perez, Harvey; Anderson, A J; Cummings, B J



Temperature Dependent Equilibrium Native to Unfolded Protein Dynamics and Properties Observed with IR Absorption and 2D IR Vibrational Echo Experiments  

PubMed Central

Dynamic and structural properties of carbonmonoxy (CO)-coordinated cytochrome c552 from Hydrogenobacter thermophilus (Ht-M61A) at different temperatures under thermal equilibrium conditions were studied with infrared absorption spectroscopy and ultrafast two dimensional infrared (2D IR) vibrational echo experiments using the heme-bound CO as the vibrational probe. Depending on the temperature, the stretching mode of CO shows two distinct bands corresponding to the native and unfolded proteins. As the temperature is increased from low temperature, a new absorption band for the unfolded protein grows in and the native band decreases in amplitude. Both the temperature dependent circular dichroism and the IR absorption area ratio RA(T), defined as the ratio of the area under the unfolded band to the sum of the areas of the native and unfolded bands, suggest a two-state transition from the native to the unfolded protein. However, it is found that the absorption spectrum of the unfolded protein increases its inhomogeneous linewidth and the center frequency shifts as the temperature is increased. The changes in linewidth and center frequency demonstrate that the unfolding does not follow simple two-state behavior. The temperature dependent 2D IR vibrational echo experiments show that the fast dynamics of the native protein are virtually temperature independent. In contrast, the fast dynamics of the unfolded protein are slower than those of the native protein, and the unfolded protein fast dynamics and at least a portion of the slower dynamics of the unfolded protein change significantly, becoming faster as the temperature is raised. The temperature dependence of the absorption spectrum and the changes in dynamics measured with the 2D IR experiments confirm that the unfolded ensemble of conformers continuously changes its nature as unfolding proceeds, in contrast to the native state, which displays a temperature independent distribution of structures.

Chung, Jean K.; Thielges, Megan C.; Bowman, Sarah E. J.; Bren, Kara L.; Fayer, M. D.



Study of center-bias in the viewing of stereoscopic image and a framework for extending 2D visual attention models to 3D  

NASA Astrophysics Data System (ADS)

Compared to the good performance that can be achieved by many 2D visual attention models, predicting salient regions of a 3D scene is still challenging. An efficient way to achieve this can be to exploit existing models designed for 2D content. However, the visual conflicts caused by binocular disparity and changes of viewing behavior in 3D viewing need to be dealt with. To cope with these, the present paper proposes a simple framework for extending 2D attention models for 3D images, well as evaluates center-bias in 3D-viewing condition. To validate the results, a database is created, which contains eye-movements of 35 subjects recorded during free viewing of eighteen 3D images and their corresponding 2D version. Fixation density maps indicate a weaker center-bias in the viewing of 3D images. Moreover, objective metric results demonstrate the efficiency of the proposed model and a large added value of center-bias when it is taken into account in computational modeling of 3D visual attention.

Wang, Junle; Perreira Da Silva, Matthieu; Le Callet, Patrick; Ricordel, Vincent



Relationship of Ca2+ sparks to STOCs studied with 2D and 3D imaging in feline oesophageal smooth muscle cells  

PubMed Central

We recorded Ca2+ sparks and spontaneous transient outward currents (STOCs) simultaneously in smooth muscle cells using whole-cell patch recording and a unique, high-speed widefield digital imaging system to monitor fluo-3 fluorescence in both two and three dimensions (2D and 3D). In 2D imaging, the correlation between the amplitude of a spark and its corresponding STOC was a weak one, and 27 % of the sparks failed to cause STOCs. The STOCless sparks were not significantly different in amplitude from those that caused STOCs. Three-dimensional imaging disclosed that STOCless sparks were located close to the cell surface, and on average their apparent distance from the cell surface was not significantly different from the sparks that cause STOCs. Statistical evaluation of spark clusters disclosed that there were regions of the cell where the probability of spark occurrence was high and others where it was quite low.

Kirber, Michael T; Etter, Elaine F; Bellve, Karl A; Lifshitz, Lawrence M; Tuft, Richard A; Fay, Fredric S; Walsh, John V; Fogarty, Kevin E



Fast search for thresholds from 1D and 2D histograms by an iterative algorithm for image segmentation  

Microsoft Academic Search

Image segmentation plays a very important role in many tasks of pattern recognition, computer vision, and image and video retrieval. In applications such as real-time recognition and tracking systems, it is desirable to develop as fast segmentation algorithms as possible. Image thresholding is one of the most important techniques for image segmentation. Its goal is to automatically find thresholds from

Liju Dong; Ge Yu



Analysis of the coefficients of generalized bilinear transformation in the design of 2-D band-pass and band-stop filters and an application in image processing  

Microsoft Academic Search

Due to rapid progress in the field of speech and image processing, there is a greater need of a digital filter which possesses variable magnitude characteristics; one such filter is proposed in this paper. The proposed 2-D band-pass and band-elimination filters are designed from a 1-D low-pass Butterworth filter by applying a low-pass to band-pass and low-pass to band-stop transformations

Karthikeyan K. Sundaram; Venkat Ramachandran



Multi-scale line segmentation with automatic estimation of width, contrast and tangential direction in 2D and 3D medical images  

Microsoft Academic Search

A new multi-scale segmentation technique for line-like structures in 2D and 3D medical images is presented. It is based on normalized first and second derivatives and on the eigenvector analysis of the hessian matrix. Application areas are the segmentation and tracking of bloodvessels, electrodes, catheters and other line-like objects. It allows for the estimation of the local diameter, the longitudinal

Cristian Lorenz; I.-C. Carlsen; Thorsten M. Buzug; Carola Fassnacht; Jürgen Weese



2D multi-parameter elastic seismic imaging by frequency-domain L1-norm full waveform inversion  

NASA Astrophysics Data System (ADS)

Full waveform inversion (FWI) is becoming a powerful and efficient tool to derive high-resolution quantitative models of the subsurface. In the frequency-domain, computationally efficient FWI algorithms can be designed for wide-aperture acquisition geometries by limiting inversion to few discrete frequencies. However, FWI remains an ill-posed and highly non-linear data-fitting procedure that is sensitive to noise, inaccuracies of the starting model and definition of multiparameter classes. The footprint of the noise in seismic imaging is conventionally mitigated by stacking highly redundant multifold data. However, when the data redundancy is decimated in the framework of efficient frequency-domain FWI, it is essential to assess the sensitivity of the inversion to noise. The impact of the noise in FWI, when applied to decimated data sets, has been marginally illustrated in the past and least-squares minimisation has remained the most popular approach. We investigate in this study the sensitivity of frequency-domain elastic FWI to noise for realistic onshore and offshore synthetic data sets contaminated by ambient random white noise. Four minimisation functionals are assessed in the framework of frequency domain FWI of decimated data: the classical least-square norm (L2), the least-absolute-values norm (L1), and some combinations of both (the Huber and the so-called Hybrid criteria). These functionals are implemented in a massively-parallel, 2D elastic frequency-domain FWI algorithm. A two-level hierarchical algorithm is implemented to mitigate the non-linearity of the inversion in complex environments. The first outer level consists of successive inversions of frequency groups of increasing high-frequency content. This level defines a multi-scale approach while preserving some data redundancy by means of simultaneous inversion of multiple frequencies. The second inner level used complex-valued frequencies for data preconditioning. This preconditioning controls the amount of the data involved in the inversion from the first-arrival time and allows us to mitigate the weight of the complex late arrivals during the first iterations of the inversion. We applied our FWI approach to the SEG/EAGE overthrust model and the shallow-water Valhall model which is representative of oil and gas fields in North Sea. Results show that the L1 norm provides the most reliable models for both applications, even when only few discrete frequencies are used in the inversion and outliers pollute the data. The L2 norm can provide reliable results in the presence of uniform white noise only if the data redundancy is increased by refining the frequency sampling interval in the inversion, at the expense of the computational efficiency. The Huber and the Hybrid criteria are shown to be sensitive to a threshold, which controls the transition between the L1 and L2 behaviours, and which requires tedious trial-and-error investigations for reliable estimation. We show that the L1 norm provides a robust alternative to the classical approach based on the L2 norm for the inversion of decimated data sets in the framework of efficient frequency-domain FWI.

Brossier, Romain; Operto, Stéphane; Virieux, Jean



Quantitative textural analysis of Vulcanian pyroclasts (Montserrat) using multi-scale X-ray computed microtomography: comparison with results from 2D image analysis  

NASA Astrophysics Data System (ADS)

X-ray computed microtomography (?CT) was carried out on four pyroclasts from the 1997 Vulcanian explosions of Soufrière Hills Volcano, Montserrat. Three-dimensional data from multiple image stacks with different spatial resolutions (0.37, 4-8, and 17.4 ?m px-1) were combined to generate size distributions of vesicles, inter-vesicle throats, crystals, and Fe-Ti oxides over a 3.4-860-?m size range, and to compare the results with those obtained by 2D image analysis on the same samples. Qualitative textural observations are in good agreement with those made in 2D, but ?CT provides better resolution of textural features and spatial relationships. Calculation of size distributions requires automated decoalescence of the connected vesicle network. Problems related to this process, in part due to the high porosity of pumice, result in potential artefacts in the calculated size distributions, which are discussed in detail. The main modes of the 3D vesicle volume distributions are systematically shifted to larger sizes compared with those of the 2D distributions. Sample total vesicularities obtained in 3D are within 13 vol.% of those found in 2D, and within 10 vol.% of those measured by He-pycnometry. Total number densities of vesicles and Fe-Ti oxides from the two methods are consistent only to the first order, 3D values ranging from 37% to 309% of those in 2D. Vesicle coalescence, investigated by examining inter-vesicle throat size distributions, occurred in all pyroclasts between neighbouring vesicles of many sizes. The larger the vesicle, the more connected it is.

Giachetti, Thomas; Burgisser, A.; Arbaret, L.; Druitt, T. H.; Kelfoun, K.



Simultaneous image segmentation and medial structure estimation: application to 2D and 3D vessel tree extraction  

Microsoft Academic Search

We propose a variational approach which combines automatic segmentation and medial structure extraction in a single computationally efficient algorithm. In this paper, we apply our approach to the analysis of vessels in 2D X-ray angiography and 3D X-ray rotational angiography of the brain. Other variational methods proposed in the literature encode the medial structure of vessel trees as a skeleton

Sherif Makram-Ebeid; Jean Stawiaski; Guillaume Pizaine



Optimizing sequential dual tracer P.E.T. studies using a combined 2D\\/3D imaging protocol  

Microsoft Academic Search

We have investigated a combined 2D\\/3D protocol for minimizing contamination in dual tracer P.E.T. studies in which the tracers are administered on a timescale that is short compared to the half-lives. We have performed a series of phantom studies on an Advance and a Discovery ST (GE Healthcare Technologies), using a torso phantom with cardiac insert (Data Spectrum Corporation) to

John W. Wilson; Timothy G. Turkington; James G. Colsher; Salvador Borges-Neto; Robert E. Reiman; R. E. Coleman



A Data Acquisition and 2-D Flow Measuring Technology in Agricultural Spray Field Based on High Speed Image Processing  

Microsoft Academic Search

In order to solve the faults in usual measurements of droplet distribution and motion in agricultural spraying field, a new method is given for the analysis of droplets characteristics and motion with PDIA (particle \\/ droplet image analysis) and digital image processing technique. During the analysis of the size of droplet and the velocity, images of droplets in spray field

Lu Jun; Li Pingping



An integrated circuit with transmit beamforming flip-chip bonded to a 2-D CMUT array for 3-D ultrasound imaging.  


State-of-the-art 3-D medical ultrasound imaging requires transmitting and receiving ultrasound using a 2-D array of ultrasound transducers with hundreds or thousands of elements. A tight combination of the transducer array with integrated circuitry eliminates bulky cables connecting the elements of the transducer array to a separate system of electronics. Furthermore, preamplifiers located close to the array can lead to improved receive sensitivity. A combined IC and transducer array can lead to a portable, high-performance, and inexpensive 3-D ultrasound imaging system. This paper presents an IC flip-chip bonded to a 16 x 16-element capacitive micromachined ultrasonic transducer (CMUT) array for 3-D ultrasound imaging. The IC includes a transmit beamformer that generates 25-V unipolar pulses with programmable focusing delays to 224 of the 256 transducer elements. One-shot circuits allow adjustment of the pulse widths for different ultrasound transducer center frequencies. For receiving reflected ultrasound signals, the IC uses the 32-elements along the array diagonals. The IC provides each receiving element with a low-noise 25-MHz-bandwidth transimpedance amplifier. Using a field-programmable gate array (FPGA) clocked at 100 MHz to operate the IC, the IC generated properly timed transmit pulses with 5-ns accuracy. With the IC flip-chip bonded to a CMUT array, we show that the IC can produce steered and focused ultrasound beams. We present 2-D and 3-D images of a wire phantom and 2-D orthogonal cross-sectional images (Bscans) of a latex heart phantom. PMID:19942502

Wygant, Ira O; Jamal, Nafis S; Lee, Hyunjoo J; Nikoozadeh, Amin; Oralkan, Omer; Karaman, Mustafa; Khuri-Yakub, Butrus T



Body image, shape, and volumetric assessments using 3D whole body laser scanning and 2D digital photography in females with a diagnosed eating disorder: preliminary novel findings.  


We piloted three-dimensional (3D) body scanning in eating disorder (ED) patients. Assessments of 22 ED patients (including nine anorexia nervosa (AN) patients, 12 bulimia nervosa (BN) patients, and one patient with eating disorder not otherwise specified) and 22 matched controls are presented. Volunteers underwent visual screening, two-dimensional (2D) digital photography to assess perception and dissatisfaction (via computerized image distortion), and adjunctive 3D full-body scanning. Patients and controls perceived themselves as bigger than their true shape (except in the chest region for controls and anorexia patients). All participants wished to be smaller across all body regions. Patients had poorer veridical perception and greater dissatisfaction than controls. Perception was generally poorer and dissatisfaction greater in bulimia compared with anorexia patients. 3D-volume:2D-area relationships showed that anorexia cases had least tissue on the torso and most on the arms and legs relative to frontal area. The engagement of patients with the scanning process suggests a validation study is viable. This would enable mental constructs of body image to be aligned with segmental volume of body areas, overcoming limitations, and errors associated with 2D instruments restricted to frontal (coronal) shapes. These novel data could inform the design of clinical trials in adjunctive treatments for eating disorders. PMID:22506746

Stewart, Arthur D; Klein, Susan; Young, Julie; Simpson, Susan; Lee, Amanda J; Harrild, Kirstin; Crockett, Philip; Benson, Philip J



Spatio-temporal (2D+T) non-rigid registration of real-time 3D echocardiography and cardiovascular MR image sequences  

NASA Astrophysics Data System (ADS)

In this paper we describe a method to non-rigidly co-register a 2D slice sequence from real-time 3D echocardiography with a 2D cardiovascular MR image sequence. This is challenging because the imaging modalities have different spatial and temporal resolution. Non-rigid registration is required for accurate alignment due to imprecision of cardiac gating and natural motion variations between cardiac cycles. In our approach the deformation field between the imaging modalities is decoupled into temporal and spatial components. First, temporal alignment is performed to establish temporal correspondence between a real-time 3D echocardiography frame and a cardiovascular MR frame. Spatial alignment is then performed using an adaptive non-rigid registration algorithm based on local phase mutual information on each temporally aligned image pair. Experiments on seven volunteer datasets are reported. Evaluation of registration errors based on expert-identified landmarks shows that the spatio-temporal registration algorithm gives a mean registration error of 3.56 ± 0.49 and 3.54 ± 0.27 mm for the short and long axis sequences, respectively.

Zhang, Weiwei; Brady, J. Michael; Becher, Harald; Noble, J. Alison



A compressed digital output CMOS image sensor with analog 2-D DCT processors and ADC\\/quantizer  

Microsoft Academic Search

Progress in CMOS-based image sensors is creating opportunities for a low-cost, low-power one-chip video camera with digitizing, signal processing and image compression. Such a smart camera head acquires compressed digital moving pictures directly into portable multimedia computers. Video encoders using a moving picture coding standard such as MPEG and H.26x are not always suitable for integration of image encoding on

Shoji Kawahito; Makoto Yoshida; Masaaki Sasaki; Keijiro Umehara; Yoshiaki Tadokoro; Kenji Murata; S. Doushod; Akira Matsuzawa



Remote Temperature Estimation in Intravascular Photoacoustic Imaging  

PubMed Central

Intravascular photoacoustic (IVPA) imaging is based on the detection of laser-induced acoustic waves generated within the arterial tissue under pulsed laser irradiation. Generally, laser radiant energy levels are kept low (20 mJ/cm2) during photoacoustic imaging to conform to general standards for safe use of lasers on biological tissues. However, safety standards in intravascular photoacoustic imaging are not yet fully established. Consequently, monitoring spatio-temporal temperature changes associated with laser-tissue interaction is important to address thermal safety of IVPA imaging. In this study we utilize the IVUS based strain measurements to estimate the laser induced temperature increase. Temporal changes in temperature were estimated in a phantom modeling a vessel with an inclusion. A cross-correlation based time delay estimator was used to assess temperature induced strains produced by different laser radiant energies. The IVUS based remote measurements revealed temperature increases of 0.7±0.3°C, 2.9±0.2 °C and 5.0±0.2 °C, for the laser radiant energies of 30 mJ/cm2, 60 mJ/cm2 and 85 mJ/cm2 respectively. The technique was then used in imaging of ex vivo samples of a normal rabbit aorta. For arterial tissues, a temperature elevation of 1.1°C was observed for a laser fluence of 60 mJ/cm2 and lesser than 1°C for lower energy levels normally associated with IVPA imaging. Therefore, the developed ultrasound technique can be used to monitor temperature during IVPA imaging. Furthermore, the analysis based on the Arrhenius thermal damage model indicates no thermal injury in the arterial tissue; suggesting the safety of IVPA imaging

Sethuraman, Shriram; Aglyamov, Salavat R.; Smalling, Richard W.; Emelianov, Stanislav Y.



Left atrial deformation parameters in patients with non-alcoholic fatty liver disease: a 2D speckle tracking imaging study.  


The presence of the metabolic syndrome is a strong predictor for the presence of NASH (non-alcoholic steatohepatitis) in patients with NAFLD (non-alcoholic fatty liver disease). In the present study, we assessed LA (left atrial) deformation parameters in patients with NAFLD using 2D-STE (speckle tracking echocardiography) and to investigate if any changes exist between subgroups of the NAFLD. A total of 55 NAFLD patients and 21 healthy controls were included in the study. The diagnosis of NAFLD was based on liver biopsy. After patients were categorized into groups according to histopathological analysis (simple steatosis, borderline NASH, definitive NASH), all patients underwent echocardiography with Doppler examination. In the 2D-STE analysis of the left atrium, LA-Res (peak LA strain during ventricular systole), LA-Pump (peak LA strain during atrial systole), LA-SRS (peak LA strain rate during ventricular systole), LA-SRE (peak LA strain rate during early diastole) and LA-SRA (peak LA strain rate during atrial systole) were obtained. LA-Res, LA-Pump and LA-SRA were lower in the NAFLD group than in the control group. LA-Res was found to be significantly lower in NAFLD subgroups compared with healthy subjects (43.9±14.2 in healthy controls compared with 31.4±8.3 with simple steatosis, 32.8±12.8 with borderline NASH and 33.8±9.0 with definitive NASH). LA-Pump was significantly lower in the NAFLD group (18.2±3.1 in healthy controls compared with 13.3±4.7 with borderline NASH and 14.4±4.7 with definitive NASH). There were significant differences in LA-SRA between healthy controls compared with simple steatosis and borderline NASH (-1.56±0.36 compared with 1.14±0.38 and 1.24±0.32 respectively). Correlation analysis showed significant correlation of LA-Res values with E (early diastolic peak velocity)/Em (early diastolic mitral annular velocity) ratio (r=-0.50, P?0.001), with LAVI (LA volume index; r=-0.45, P?0.001) and with Vp (propagation velocity; r=0.39, P?0.001). 2D-STE-based LA deformation parameters are impaired in patients with NAFLD with normal systolic function. Although LA-Res and pump function parameters might be useful in estimating LV (left ventricular) filling pressure in the NAFLD patient group, it could not be used for differentiating the subgroups. PMID:23947743

Kocabay, Gonenc; Karabay, Can Yucel; Colak, Yasar; Oduncu, Vecih; Kalayci, Arzu; Akgun, Taylan; Guler, Ahmet; Kirma, Cevat



Monotonic and Fatigue Behavior of 2-D Woven Ceramic Matrix Composite at Room and Elevated Temperatures (Blackglas/Nextel 312).  

National Technical Information Service (NTIS)

This study investigated the monotonic tension and compression and the tension-tension and tension-compression fatigue loading of Blackglas/Nextel 312 woven CMC at room temperature and at 760 degrees centigrade. Young's Modulus and strain variation were ev...

M. Al-Hussein



Sensor fusion of 2D and 3D data for the processing of images of dental imprints  

NASA Astrophysics Data System (ADS)

This paper presents a computer vision system for the acquisition and processing of 3-D images of wax dental imprints. The ultimate goal of the system is to measure a set of 10 orthodontic parameters that will be fed to an expert system for automatic diagnosis of occlusion problems. An approach for the acquisition of range images of both sides of the imprint is presented. Range is obtained from a shape-from-absorption technique applied to a pair of grey-level images obtained at two different wavelengths. The accuracy of the range values is improved using sensor fusion between the initial range image and a reflectance image from the pair of grey-level images. The improved range image is segmented in order to find the interstices between teeth and, following further processing, the type of each tooth on the profile. Once each tooth has been identified, its accurate location on the imprint is found using a region- growing approach and its shape is reconstructed with third degree polynomial functions. The reconstructed shape will be later used by the system to find specific features that are needed to estimate the orthodontic parameters.

Methot, Jean-Francois; Mokhtari, Marielle; Laurendeau, Denis; Poussart, Denis



Simultaneous Microwave Imaging System for Density and Temperature Fluctuation Measurements on TEXTOR  

SciTech Connect

Diagnostic systems for fluctuation measurements in plasmas have, of necessity, evolved from simple 1-D systems to multi-dimensional systems due to the complexity of the MHD and turbulence physics of plasmas illustrated by advanced numerical simulations. Using the recent significant advancements in millimeter wave imaging technology, Microwave Imaging Reflectometry (MIR) and Electron Cyclotron Emission Imaging (ECEI), simultaneously measuring density and temperature fluctuations, are developed for TEXTOR. The MIR system was installed on TEXTOR and the first experiment was performed in September, 2003. Subsequent MIR campaigns have yielded poloidally resolved spectra and assessments of poloidal velocity. The new 2-D ECE Imaging system (with a total of 128 channels), installed on TEXTOR in December, 2003, successfully captured a true 2-D images of Te fluctuations of m=1 oscillation (''sawteeth'') near the q {approx} 1 surface for the first time.

H. Park; E. Mazzucato; T. Munsat; C.W. Domier; M. Johnson; N.C. Luhmann, Jr.; J. Wang; Z. Xia; I.G.J. Classen; A.J.H. Donne; M.J. van de Pol



High-performance GPU-based rendering for real-time, rigid 2D/3D-image registration and motion prediction in radiation oncology.  


A common problem in image-guided radiation therapy (IGRT) of lung cancer as well as other malignant diseases is the compensation of periodic and aperiodic motion during dose delivery. Modern systems for image-guided radiation oncology allow for the acquisition of cone-beam computed tomography data in the treatment room as well as the acquisition of planar radiographs during the treatment. A mid-term research goal is the compensation of tumor target volume motion by 2D/3D Registration. In 2D/3D registration, spatial information on organ location is derived by an iterative comparison of perspective volume renderings, so-called digitally rendered radiographs (DRR) from computed tomography volume data, and planar reference x-rays. Currently, this rendering process is very time consuming, and real-time registration, which should at least provide data on organ position in less than a second, has not come into existence. We present two GPU-based rendering algorithms which generate a DRR of 512×512 pixels size from a CT dataset of 53 MB size at a pace of almost 100 Hz. This rendering rate is feasible by applying a number of algorithmic simplifications which range from alternative volume-driven rendering approaches - namely so-called wobbled splatting - to sub-sampling of the DRR-image by means of specialized raycasting techniques. Furthermore, general purpose graphics processing unit (GPGPU) programming paradigms were consequently utilized. Rendering quality and performance as well as the influence on the quality and performance of the overall registration process were measured and analyzed in detail. The results show that both methods are competitive and pave the way for fast motion compensation by rigid and possibly even non-rigid 2D/3D registration and, beyond that, adaptive filtering of motion models in IGRT. PMID:21782399

Spoerk, Jakob; Gendrin, Christelle; Weber, Christoph; Figl, Michael; Pawiro, Supriyanto Ardjo; Furtado, Hugo; Fabri, Daniella; Bloch, Christoph; Bergmann, Helmar; Gröller, Eduard; Birkfellner, Wolfgang



Preliminary clinical results: an analyzing tool for 2D optical imaging in detection of active inflammation in rheumatoid arthritis  

NASA Astrophysics Data System (ADS)

Optical imaging (OI) is a relatively new method in detecting active inflammation of hand joints of patients suffering from rheumatoid arthritis (RA). With the high number of people affected by this disease especially in western countries, the availability of OI as an early diagnostic imaging method is clinically highly relevant. In this paper, we present a newly in-house developed OI analyzing tool and a clinical evaluation study. Our analyzing tool extends the capability of existing OI tools. We include many features in the tool, such as region-based image analysis, hyper perfusion curve analysis, and multi-modality image fusion to aid clinicians in localizing and determining the intensity of inflammation in joints. Additionally, image data management options, such as the full integration of PACS/RIS, are included. In our clinical study we demonstrate how OI facilitates the detection of active inflammation in rheumatoid arthritis. The preliminary clinical results indicate a sensitivity of 43.5%, a specificity of 80.3%, an accuracy of 65.7%, a positive predictive value of 76.6%, and a negative predictive value of 64.9% in relation to clinical results from MRI. The accuracy of inflammation detection serves as evidence to the potential of OI as a useful imaging modality for early detection of active inflammation in patients with rheumatoid arthritis. With our in-house developed tool we extend the usefulness of OI imaging in the clinical arena. Overall, we show that OI is a fast, inexpensive, non-invasive and nonionizing yet highly sensitive and accurate imaging modality.-

Adi Aizudin Bin Radin Nasirudin, Radin; Meier, Reinhard; Ahari, Carmen; Sievert, Matti; Fiebich, Martin; Rummeny, Ernst J.; Noël, Peter B.



Temperature dependence of CDW and d-wave pair correlations in the 2D extended Hubbard model  

Microsoft Academic Search

Using the auxiliary field quantum Monte Carlo (QMC) method, we study the 2×2 charge density wave (CDW) and d-wave pair correlation functions of the square-lattice extended Hubbard model with intersite Coulomb repulsions. We confirm the existence of a finite-temperature CDW transition which belongs to the 3D Ising universality class at half filling and near half filling. We also find that

Y. Fukumoto; A. Oguchi



Model-based measurement of food portion size for image-based dietary assessment using 3D/2D registration  

NASA Astrophysics Data System (ADS)

Dietary assessment is important in health maintenance and intervention in many chronic conditions, such as obesity, diabetes and cardiovascular disease. However, there is currently a lack of convenient methods for measuring the volume of food (portion size) in real-life settings. We present a computational method to estimate food volume from a single photographic image of food contained on a typical dining plate. First, we calculate the food location with respect to a 3D camera coordinate system using the plate as a scale reference. Then, the food is segmented automatically from the background in the image. Adaptive thresholding and snake modeling are implemented based on several image features, such as color contrast, regional color homogeneity and curve bending degree. Next, a 3D model representing the general shape of the food (e.g., a cylinder, a sphere, etc) is selected from a pre-constructed shape model library. The position, orientation and scale of the selected shape model are determined by registering the projected 3D model and the food contour in the image, where the properties of the reference are used as constraints. Experimental results using various realistically shaped foods with known volumes demonstrated satisfactory performance of our image-based food volume measurement method even if the 3D geometric surface of the food is not completely represented in the input image.

Chen, Hsin-Chen; Jia, Wenyan; Yue, Yaofeng; Li, Zhaoxin; Sun, Yung-Nien; Fernstrom, John D.; Sun, Mingui



Communication: two-dimensional gas-phase coherent anti-Stokes Raman spectroscopy (2D-CARS): simultaneous planar imaging and multiplex spectroscopy in a single laser shot.  


Coherent anti-Stokes Raman spectroscopy (CARS) has been widely used as a powerful tool for chemical sensing, molecular dynamics measurements, and rovibrational spectroscopy since its development over 30 years ago, finding use in fields of study as diverse as combustion diagnostics, cell biology, plasma physics, and the standoff detection of explosives. The capability for acquiring resolved CARS spectra in multiple spatial dimensions within a single laser shot has been a long-standing goal for the study of dynamical processes, but has proven elusive because of both phase-matching and detection considerations. Here, by combining new phase matching and detection schemes with the high efficiency of femtosecond excitation of Raman coherences, we introduce a technique for single-shot two-dimensional (2D) spatial measurements of gas phase CARS spectra. We demonstrate a spectrometer enabling both 2D plane imaging and spectroscopy simultaneously, and present the instantaneous measurement of 15,000 spatially correlated rotational CARS spectra in N2 and air over a 2D field of 40 mm(2). PMID:23781772

Bohlin, Alexis; Kliewer, Christopher J



Communication: Two-dimensional gas-phase coherent anti-Stokes Raman spectroscopy (2D-CARS): Simultaneous planar imaging and multiplex spectroscopy in a single laser shot  

NASA Astrophysics Data System (ADS)

Coherent anti-Stokes Raman spectroscopy (CARS) has been widely used as a powerful tool for chemical sensing, molecular dynamics measurements, and rovibrational spectroscopy since its development over 30 years ago, finding use in fields of study as diverse as combustion diagnostics, cell biology, plasma physics, and the standoff detection of explosives. The capability for acquiring resolved CARS spectra in multiple spatial dimensions within a single laser shot has been a long-standing goal for the study of dynamical processes, but has proven elusive because of both phase-matching and detection considerations. Here, by combining new phase matching and detection schemes with the high efficiency of femtosecond excitation of Raman coherences, we introduce a technique for single-shot two-dimensional (2D) spatial measurements of gas phase CARS spectra. We demonstrate a spectrometer enabling both 2D plane imaging and spectroscopy simultaneously, and present the instantaneous measurement of 15 000 spatially correlated rotational CARS spectra in N2 and air over a 2D field of 40 mm2.

Bohlin, Alexis; Kliewer, Christopher J.



2D and 3D Prestack Depth Migration Seismic Imaging around NanTroSEIZE LWD sites as a mission for the IODP Implementing Organization  

NASA Astrophysics Data System (ADS)

Since 1997, 2D seismic sections were acquired across the Nankai Trough by IFREE/JAMSTEC. Based on these crustal structure studies for site survey purposes, the NanTroSEIZE drilling plan has been solidified. In 2003, CDEX acquired an additional commercial 2D MCS survey of closely spaced, high resolution. We used a single 4240 in3 source and a 6000 m streamer. The purpose of these site surveys is to reveal a higher resolution image and to define the seismic characteristics of the accretionary prism in order to operate safety and smoothly during NanTroSEIZE drilling. We performed 2D seismic processing as follows: apply minimum phase anti-alias filter, resample to 4 ms, velocity analysis, adjacent trace sum with differential normal moveout, compensation for recording delay, static sea level correction, spherical divergence correction, and surface consistent deconvolution. We also refined our velocity model at the drilling sites by comparing the 2D seismic sections and Ocean Bottom Seismograph (OBS) data acquired along the same line by IFREE/JAMSTEC. A 3D seismic survey by M/V Nordic Explorer was carried out in May, 2006. This is the first 3D site survey using a commercial seismic vessel. We designed track lines to cover a box region around the proposed drilling sites and around 10km deep penetration. The system configuration was as follows: four 4500m streamers and double array sources of G-guns with 3090 in3., alternate firing at 37.5m interval, resulting in a 792 km2 survey. Commercial processing consisted of noise and multiple removal and 3D pre-stack time migration. At IFREE/JAMSTEC we conducted full 3D depth imaging, including a velocity model that proved to be excellent at the NanTroSEIZE drill sites. We were able to calibrate the depth/velocity model with well markers and to make judgement a true depth of fracture and fault zone of the accretionary prism. In August, 2008, we obtained an additional 2D MCS survey northeast of the current transect forpotential riser drilling sites. These data will be pre-stack depth migrated to obtain a better understanding of the complex structures in this area.

Kido, Y.; Sanada, Y.; Uraki, S.; Kuaramoto, S.; Kawamura, Y.; Moore, G. F.



Simultaneous image segmentation and medial structure estimation: application to 2D and 3D vessel tree extraction  

NASA Astrophysics Data System (ADS)

We propose a variational approach which combines automatic segmentation and medial structure extraction in a single computationally efficient algorithm. In this paper, we apply our approach to the analysis of vessels in 2D X-ray angiography and 3D X-ray rotational angiography of the brain. Other variational methods proposed in the literature encode the medial structure of vessel trees as a skeleton with associated vessel radii. In contrast, our method provides a dense smooth level set map which sign provides the segmentation. The ridges of this map define the segmented regions skeleton. The differential structure of the smooth map (in particular the Hessian) allows the discrimination between tubular and other structures. In 3D, both circular and non-circular tubular cross-sections and tubular branching can be handled conveniently. This algorithm allows accurate segmentation of complex vessel structures. It also provides key tools for extracting anatomically labeled vessel tree graphs and for dealing with challenging issues like kissing vessel discrimination and separation of entangled 3D vessel trees.

Makram-Ebeid, Sherif; Stawiaski, Jean; Pizaine, Guillaume



A 2-D basin-scale methane hydrate model: equilibrium and transient sensitivity to ocean temperature. (Invited)  

NASA Astrophysics Data System (ADS)

Carbon and oxygen isotopic variations through the Paleocene-Eocene thermal maximum event suggest that biogenic methane was not the source of the perturbing carbon, but this does not guarantee that the hydrates on Earth today will not eventually respond to the unique provocation of the global warming climate event. The SpongeBOB ocean methane hydrate model is used to simulate the accumulation of sediment along a passive continental margin over geologic time scales. Fluid motions within the sediment column are driven by compaction and variations in sediment permeability, and they impact the efficiency of methane trapping within hydrate deposits. The equilibrium and transient sensitivity of the methane inventory in the sediments to the temperature of the ocean will be assessed.

Archer, D. E.; McGuire, P. C.; Buffett, B. A.



Factors Affecting the Correlation Coefficient Template Matching Algorithm with Application to Real-Time 2D Coronary Artery MR Imaging  

Microsoft Academic Search

This paper characterizes factors affecting the accuracy of the correlation coefficient (CC) template matching algorithm, as applied to motion tracking from two-dimensional real-time coronary artery magnetic resonance images. The performance of this algorithm is analyzed in the presence of both random and systematic error. In the presence of random error, it is shown that a necessary and sufficient condition for

Marshall S. Sussman; Graham A. Wright



A general approach for multifeature multisensor classification and localization of 3D objects in 2D image sequences  

NASA Astrophysics Data System (ADS)

In this paper, we present a novel approach for multiple-feature, multiple-sensor classification and localization of three-dimensional objects in two-dimensional images. We use a hypothesize-and-test-approach where we fit three-dimensional geometric models to image data. A hypothesis consists of an object's class and its six degrees of freedom. Our models consist of the objects' geometric data which is attributed with several local features, e.g. hotspots, edges and textures, and their respective rule of applicability (e.g. visibility). The model-fitting process is divided into three parts: using the hypothesis we first project the object onto the image plane while evaluating the rules of applicability for its local features. Hence, we get a two-dimensional representation of the objects which - in a second step - is aligned to the image data. In the last step, we perform a pose estimation to calculate the object's six degrees of freedom and to update the hypothesis out of the alignment results. The paper describes the major components of our system. This includes the management and generation of the hypotheses, the matching process, the pose estimation, and model-based prediction of the object's pose in six degrees of freedom. At the end, we show the performance, robustness and accuracy of the system in two applications (optical inspection for quality control and airport ground-traffic surveillance).

Koelzow, Thorsten; Ellenrieder, Marc M.



Ultrasonography-based 2D motion-compensated HIFU sonication integrated with reference-free MR temperature monitoring: a feasibility study ex vivo.  


Magnetic resonance imaging (MRI) and ultrasonography have been used simultaneously in this ex vivo study for the image-guidance of high intensity focused ultrasound (HIFU) treatment in moving tissue. A ventilator-driven balloon produced periodic and non-rigid (i.e. breathing-like) motion patterns in phantoms. MR-compatible ultrasound (US) imaging enabled near real-time 2D motion tracking based on optical flow detection, while near-harmonic reference-free proton resonance frequency shift (PRFS) MR thermometry (MRT) was used to monitor the thermal buildup on line. Reference-free MRT was applied to gradient-echo echo-planar imaging phase maps acquired at the frame rate of 250 to 300 ms/slice with voxel size 1.25×1.25×5 mm(3). The MR-US simultaneous imaging was completely free of mutual interferences while minor RF interferences from the HIFU device were detected in the far field of the US images. The effective duty-cycle of the HIFU sonication was close to 100 % and no off-interval was required to temporally decouple it from the ultrasonography. The motion compensation of the HIFU sonication was achieved with an 8 Hz frame rate and sub-millimeter spatial accuracy, both for single-focus mode and for an iterated multi-foci line scan. Near harmonic reference-less PRFS MRT delivered motion-robust thermal maps perpendicular or parallel to the HIFU beam (0.7 °C precision, 0.5 °C absolute accuracy). Out-of-plane motion compensation was not addressed in this study. PMID:22517112

Auboiroux, Vincent; Petrusca, Lorena; Viallon, Magalie; Goget, Thomas; Becker, Christoph D; Salomir, Rares



Preliminary 3D Depth Migration of a Network of 2D Seismic Lines for Fault Imaging at a Pyramid Lake, Nevada Geothermal Prospect  

NASA Astrophysics Data System (ADS)

Many of the current geothermal power plants in western Nevada are found in extensional regimes that are associated with dilational faults and fault intersections. Most of these systems are blind and require advanced seismic imaging techniques to map target faults and reduce drilling risk. Surface features including fumaroles, hot springs, or hydrothermal deposits, like travertine and tufa, are indicators of a potential geothermal resource at depth, which still require advanced seismic imaging techniques for efficient development. One of the most notable locations of tufa deposits in western Nevada is in and around Pyramid Lake. With the abundant hydrothermal venting in the area, the tufa deposits indicate a prime locations for geothermal exploration. In 2010 and previous years, we collected about 38 km of vibroseis reflection data in a network of sixteen 2D lines of various orientations off the northwest side of Pyramid Lake. Most of these lines are within an area of only 10 square km. The 2010 survey used three heavy vibrators, and recorded 6-sec records of 8-sec, 10-100 Hz linear sweeps. Source and receiver spacing varied from 17-67 m, with up to 240 channels live for maximum offsets varying from 1000-5000 m, depending on line length. Preliminary 2D processing with first-arrival velocity optimization shows strong fault-plane reflections and several sets of stratigraphic terminations against faults. We interpret three sets of faults, which appear to intersect at about 1.25 km depth. Despite the three fault sets each appearing on several lines, only the lines trending perpendicular to fault strike show direct imaging of fault-plane reflections. We hypothesize that a 3D depth migration will reveal additional direct images of the faults. We are testing this hypothesis with a 3D Kirchhoff prestack migration of the data from this dense network of 2D lines. The 3D depth migration will take full account of lateral velocity changes. This migration should directly image additional steeply dipping fault planes at this prospect. The Pyramid Lake Paiute Tribe will use this information to build 3D geologic and hydrologic models for geothermal power development.

Frary, R.; Louie, J. N.; Pullammanappallil, S.; Eisses, A.



A novel technique for single-shot energy-resolved 2D x-ray imaging of plasmas relevant for the inertial confinement fusion.  


A novel x-ray diagnostic of laser-fusion plasmas is described, allowing 2D monochromatic images of hot, dense plasmas to be obtained in any x-ray photon energy range, over a large domain, on a single-shot basis. The device (named energy-encoded pinhole camera) is based upon the use of an array of many pinholes coupled to a large area CCD camera operating in the single-photon mode. The available x-ray spectral domain is only limited by the quantum efficiency of scientific-grade x-ray CCD cameras, thus extending from a few keV up to a few tens of keV. Spectral 2D images of the emitting plasma can be obtained at any x-ray photon energy provided that a sufficient number of photons had been collected at the desired energy. Results from recent inertial confinement fusion related experiments will be reported in order to detail the new diagnostic. PMID:23126763

Labate, L; Köster, P; Levato, T; Gizzi, L A



The effect of interface-roughness and dislocation scattering on low temperature mobility of 2D electron gas in GaN/AlGaN  

NASA Astrophysics Data System (ADS)

We present the results of our experimental and theoretical studies concerning the temperature dependence of electron mobility in a two-dimensional electron gas (2DEG) confined at the GaN/AlGaN interface. Experimental mobility of 2912 cm2 (V s)-1 at 4.2 K, remains almost constant up to lattice temperature TL = 150 K, it then decreases rapidly down to 1067 cm2 (V s)-1 at TL = 300 K. In order to compare the experimental results with the theory we use a simple analytical formula for low-field electron mobility based on 2D degenerate statistics for a 2DEG confined in a triangular well. We consider acoustic phonon, polar-optical phonon, dislocation and interface-roughness (IFR) scattering. The polar-optical phonon scattering is the dominant mechanism at high temperatures. At low temperatures, however, both the IFR and dislocation scattering explain, equally well, the observed mobility. In reality, however, a mixture of the two mechanisms together with the deformation potential and piezoelectric scattering will determine the low temperature mobility. The experimental results are discussed in the light of the calculations.

Zanato, D.; Gokden, S.; Balkan, N.; Ridley, B. K.; Schaff, W. J.



A high-frequency transimpedance amplifier for CMOS integrated 2D CMUT array towards 3D ultrasound imaging.  


One transimpedance amplifier based CMOS analog front-end (AFE) receiver is integrated with capacitive micromachined ultrasound transducers (CMUTs) towards high frequency 3D ultrasound imaging. Considering device specifications from CMUTs, the TIA is designed to amplify received signals from 17.5MHz to 52.5MHz with center frequency at 35MHz; and is fabricated in Global Foundry 0.18-µm 30-V high-voltage (HV) Bipolar/CMOS/DMOS (BCD) process. The measurement results show that the TIA with power-supply 6V can reach transimpedance gain of 61dB? and operating frequency from 17.5MHz to 100MHz. The measured input referred noise is 27.5pA/?Hz. Acoustic pulse-echo testing is conducted to demonstrate the receiving functionality of the designed 3D ultrasound imaging system. PMID:24109634

Huang, Xiwei; Cheong, Jia Hao; Cha, Hyouk-Kyu; Yu, Hongbin; Je, Minkyu; Yu, Hao



Time resolved, 2-D hard X-ray imaging of relativistic electron-beam target interactions on ETA-II  

SciTech Connect

Advanced radiographic applications require a constant source size less than 1 mm. To study the time history of a relativistic electron beam as it interacts with a bremsstrahlung converter, one of the diagnostics they use is a multi-frame time-resolved hard x-ray camera. They are performing experiments on the ETA-II accelerator at Lawrence Livermore National Laboratory to investigate details of the electron beam/converter interactions. The camera they are using contains 6 time-resolved images, each image is a 5 ns frame. By starting each successive frame 10 ns after the previous frame, they create a 6-frame movie from the hard x-rays produced from the interaction of the 50-ns electron beam pulse.

Crist, C.E. [Sandia National Labs., Albuquerque, NM (United States); Sampayan, S.; Westenskow, G.; Caporaso, G.; Houck, T.; Weir, J.; Trimble, D. [Lawrence Livermore National Lab., CA (United States); Krogh, M. [AlliedSignal FM and T, Kansas City, MO (United States)



A novel low-cost targeting system (LCTS) based upon a high-resolution 2D imaging laser radar  

NASA Astrophysics Data System (ADS)

BAE SYSTEMS has developed a Low Cost Targeting System (LCTS) consisting of a FLIR for target detection, laser-illuminated, gated imaging for target identification, laser rangefinder and designator, GPS positioning, and auto-tracking capability within a small compact system size. This system has proven its ability to acquire targets, range and identify these targets, and designate or provide precise geo-location coordinates to these targets. The system is based upon BAE Systems proven micro-bolometer passive LWIR camera coupled with Intevac's new EBAPS camera. A dual wavelength diode pumped laser provides eyesafe ranging and target illumination, as well as designation; a custom detector module senses the return pulse for target ranging and to set the range gates for the gated camera. Intevac's camera is a CMOS based device with used selectable gate widths and can read at up to 28 frames/second when operated in VGA mode. The Transferred Electron photocathode enables high performance imaging in the SWIR band by enabling single photon detection at high quantum efficiency. Trials show that the current detectors offer complete extinction of signals outside of the gated range, thus, providing high resolution within the gated region. The images have shown high spatial resolution arising from the use of solid state focal plane array technology. Imagery has been collected in both the laboratory and the field to verify system performance during a variety of operating conditions.

Grasso, Robert J.; Odhner, Jefferson E.; Wikman, John C.; Skaluba, Fred W.; Dippel, George F.; McDaniel, Robert V.; Ferrell, David S.; Seibel, William



A 2D/3D image analysis system to track fluorescently labeled structures in rod-shaped cells: application to measure spindle pole asymmetry during mitosis.  


BACKGROUND: The yeast Schizosaccharomyces pombe is frequently used as a model for studying the cell cycle. The cells are rod-shaped and divide by medial fission. The process of cell division, or cytokinesis, is controlled by a network of signaling proteins called the Septation Initiation Network (SIN); SIN proteins associate with the SPBs during nuclear division (mitosis). Some SIN proteins associate with both SPBs early in mitosis, and then display strongly asymmetric signal intensity at the SPBs in late mitosis, just before cytokinesis. This asymmetry is thought to be important for correct regulation of SIN signaling, and coordination of cytokinesis and mitosis. In order to study the dynamics of organelles or large protein complexes such as the spindle pole body (SPB), which have been labeled with a fluorescent protein tag in living cells, a number of the image analysis problems must be solved; the cell outline must be detected automatically, and the position and signal intensity associated with the structures of interest within the cell must be determined. RESULTS: We present a new 2D and 3D image analysis system that permits versatile and robust analysis of motile, fluorescently labeled structures in rod-shaped cells. We have designed an image analysis system that we have implemented as a user-friendly software package allowing the fast and robust image-analysis of large numbers of rod-shaped cells. We have developed new robust algorithms, which we combined with existing methodologies to facilitate fast and accurate analysis. Our software permits the detection and segmentation of rod-shaped cells in either static or dynamic (i.e. time lapse) multi-channel images. It enables tracking of two structures (for example SPBs) in two different image channels. For 2D or 3D static images, the locations of the structures are identified, and then intensity values are extracted together with several quantitative parameters, such as length, width, cell orientation, background fluorescence and the distance between the structures of interest. Furthermore, two kinds of kymographs of the tracked structures can be established, one representing the migration with respect to their relative position, the other representing their individual trajectories inside the cell. This software package, called "RodCellJ", allowed us to analyze a large number of S. pombe cells to understand the rules that govern SIN protein asymmetry. CONCLUSIONS: "RodCell" is freely available to the community as a package of several ImageJ plugins to simultaneously analyze the behavior of a large number of rod-shaped cells in an extensive manner. The integration of different image-processing techniques in a single package, as well as the development of novel algorithms does not only allow to speed up the analysis with respect to the usage of existing tools, but also accounts for higher accuracy. Its utility was demonstrated on both 2D and 3D static and dynamic images to study the septation initiation network of the yeast Schizosaccharomyces pombe. More generally, it can be used in any kind of biological context where fluorescent-protein labeled structures need to be analyzed in rod-shaped cells. AVAILABILITY: RodCellJ is freely available under, (after acceptance of the publication). PMID:23622681

Schmitter, Daniel; Wachowicz, Paulina; Sage, Daniel; Chasapi, Anastasia; Xenarios, Ioannis; Simanis, Viesturs; Unser, Michael



A 2D/3D image analysis system to track fluorescently labeled structures in rod-shaped cells: application to measure spindle pole asymmetry during mitosis  

PubMed Central

Background The yeast Schizosaccharomyces pombe is frequently used as a model for studying the cell cycle. The cells are rod-shaped and divide by medial fission. The process of cell division, or cytokinesis, is controlled by a network of signaling proteins called the Septation Initiation Network (SIN); SIN proteins associate with the SPBs during nuclear division (mitosis). Some SIN proteins associate with both SPBs early in mitosis, and then display strongly asymmetric signal intensity at the SPBs in late mitosis, just before cytokinesis. This asymmetry is thought to be important for correct regulation of SIN signaling, and coordination of cytokinesis and mitosis. In order to study the dynamics of organelles or large protein complexes such as the spindle pole body (SPB), which have been labeled with a fluorescent protein tag in living cells, a number of the image analysis problems must be solved; the cell outline must be detected automatically, and the position and signal intensity associated with the structures of interest within the cell must be determined. Results We present a new 2D and 3D image analysis system that permits versatile and robust analysis of motile, fluorescently labeled structures in rod-shaped cells. We have designed an image analysis system that we have implemented as a user-friendly software package allowing the fast and robust image-analysis of large numbers of rod-shaped cells. We have developed new robust algorithms, which we combined with existing methodologies to facilitate fast and accurate analysis. Our software permits the detection and segmentation of rod-shaped cells in either static or dynamic (i.e. time lapse) multi-channel images. It enables tracking of two structures (for example SPBs) in two different image channels. For 2D or 3D static images, the locations of the structures are identified, and then intensity values are extracted together with several quantitative parameters, such as length, width, cell orientation, background fluorescence and the distance between the structures of interest. Furthermore, two kinds of kymographs of the tracked structures can be established, one representing the migration with respect to their relative position, the other representing their individual trajectories inside the cell. This software package, called “RodCellJ”, allowed us to analyze a large number of S. pombe cells to understand the rules that govern SIN protein asymmetry. (Continued on next page) (Continued from previous page) Conclusions “RodCellJ” is freely available to the community as a package of several ImageJ plugins to simultaneously analyze the behavior of a large number of rod-shaped cells in an extensive manner. The integration of different image-processing techniques in a single package, as well as the development of novel algorithms does not only allow to speed up the analysis with respect to the usage of existing tools, but also accounts for higher accuracy. Its utility was demonstrated on both 2D and 3D static and dynamic images to study the septation initiation network of the yeast Schizosaccharomyces pombe. More generally, it can be used in any kind of biological context where fluorescent-protein labeled structures need to be analyzed in rod-shaped cells. Availability RodCellJ is freely available under



In vivo and in vitro characterization of R(+)-FIDA2, a novel dopamine D2/D3 receptor imaging agent  

SciTech Connect

FIDA2, (R)-(+)-2,3-dimethoxy-5-iodo-N-[1-(4`-fluorobenzyl)-2-pyrrolidinyl)-methyl]benzamide, is a new dopamine D2/D3 receptor imaging agent that can be labeled with either I-123 or F-18 for SPECT or PET imaging. In vitro binding studies of I-125 FIDA2 using dopamine D2 or D3 receptors expressed in Sf9 cells showed Kd values of 0.04 and 0.05 nM, respectively. In rat striatal homogenates, which contain a high density of dopamine D2 receptors, the ligand displayed a Kd of 0.04-0.06 nM. A series of in vivo SPECT images (transaxial sections, 2 mm) showed the radioactivity was localized in the area of the basal ganglia and reached peak concentrations in 11.2 {plus_minus} 5.9 min. The activity cleared at a rate of 33.5 {plus_minus} 9.4 %/hr. The target to nontarget ratios (basal ganglia to cerebellum) at time of peak, 1 hr, 2 hr and 3 hr p.i., were 1.1 {plus_minus} 0.4 (n=21), 3.5 {plus_minus} 1.0 (n=20), 6.3 {plus_minus} 2.9 (n=9, and 8.14 {plus_minus} 4.7 (n=9), respectively. At 90 min an injection of haloperidol or raclopride, dopamine D2/D3 receptor antagonists, displaced target activity but an injection of SCH23390, a dopamine D1 receptor antagonist, had little effect on activity in the basal ganglia. In addition, an injection of R-(+)-7-OH-PIPAT, a new ligand that is selective for the dopamine D3 receptor and the high affinity state of the dopamine D2 receptor, showed partial displacement ({approximately}15%) of I-123 FIDA2 binding in the basal ganglia. These studies indicate that FIDA2 may be a useful ligand for in vivo imaging of dopamine D2/D3 receptors.

Vessotskie, J.; Kung, M.P.; Ramaniello, G. [Univ. of Pennsylvania, Philadelphia, PA (United States)] [and others



Spatially resolved 2D attenuation image of a semi-infinite non-homogeneous tissue from diffuse reflectance  

NASA Astrophysics Data System (ADS)

Optical properties of biological tissue such as reduced scattering and absorption coefficients can be determined from the temporal or spatial reflectance curve of the diffusion process. Owing to its non-homogenous nature, the assumption of uniform optical parameters may not be valid in practice. We propose a new scheme to resolve the optical effective attenuation profile from the spatial reflectance curve of a non-homogeneous tissue. The algorithm reconstructs the linear attenuation profile along the line of measurement, rather than giving one single value for the coefficient for each reflectance curve. The technique was applied to the reconstruction of a 2-dimensional attenuation image.

Tse, Jorden; Chen, Lian-Kuan



2D soft x-ray system on DIII-D for imaging the magnetic topology in the pedestal region  

NASA Astrophysics Data System (ADS)

A new tangential two-dimensional soft x-ray imaging system (SXRIS) is being designed to examine the edge island structure in the lower X-point region of DIII-D. Plasma shielding and/or amplification of the calculated vacuum islands may play a role in the suppression of edge-localized modes via resonant magnetic perturbations (RMPs). The SXRIS is intended to improve the understanding of three-dimensional (3D) phenomena associated with RMPs. This system utilizes a tangential view with a pinhole imaging system and spectral filtering with beryllium foils. SXR emission is chosen to avoid line radiation and allows suitable signal at the top of a H-mode pedestal where Te~1-2 keV. A synthetic diagnostic calculation based on 3D SXR emissivity estimates is used to help assess signal levels and resolution of the design. A signal-to-noise ratio of 10 at 1 cm resolution is expected for the perturbed signals, which are sufficient to resolve most of the predicted vacuum island sizes.

Shafer, M. W.; Battaglia, D. J.; Unterberg, E. A.; Evans, T. E.; Hillis, D. L.; Maingi, R.



2D soft x-ray system on DIII-D for imaging the magnetic topology in the pedestal region  

SciTech Connect

A new tangential two-dimensional soft x-ray imaging system (SXRIS) is being designed to examine the edge island structure in the lower X-point region of DIII-D. Plasma shielding and/or amplification of the calculated vacuum islands may play a role in the suppression of edge-localized modes via resonant magnetic perturbations (RMPs). The SXRIS is intended to improve the understanding of three-dimensional (3D) phenomena associated with RMPs. This system utilizes a tangential view with a pinhole imaging system and spectral filtering with beryllium foils. SXR emission is chosen to avoid line radiation and allows suitable signal at the top of a H-mode pedestal where T{sub e}{approx}1-2 keV. A synthetic diagnostic calculation based on 3D SXR emissivity estimates is used to help assess signal levels and resolution of the design. A signal-to-noise ratio of 10 at 1 cm resolution is expected for the perturbed signals, which are sufficient to resolve most of the predicted vacuum island sizes.

Shafer, M. W.; Battaglia, D. J.; Unterberg, E. A.; Hillis, D. L.; Maingi, R. [Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Evans, T. E. [General Atomics, P.O. Box 85608, San Diego, California 92186-5608 (United States)



2D soft x-ray system on DIII-D for imaging the magnetic topology in the pedestal region  

SciTech Connect

A new tangential two-dimensional soft x-ray imaging system (SXRIS) is being designed to examine the edge island structure in the lower X-point region of DIII-D. Plasma shielding and/or amplification of the calculated vacuum islands may play a role in the suppression of edge-localized modes via resonant magnetic perturbations (RMPs). The SXRIS is intended to improve the understanding of three-dimensional (3D) phenomena associated with RMPs. This system utilizes a tangential view with a pinhole imaging system and spectral filtering with beryllium foils. SXR emission is chosen to avoid line radiation and allows suitable signal at the top of a H-mode pedestal where T(e) similar to 1-2 keV. A synthetic diagnostic calculation based on 3D SXR emissivity estimates is used to help assess signal levels and resolution of the design. A signal-to-noise ratio of 10 at 1 cm resolution is expected for the perturbed signals, which are sufficient to resolve most of the predicted vacuum island sizes.

Shafer, M.W. [Oak Ridge National Laboratory (ORNL); Battaglia, D. J. [Oak Ridge National Laboratory (ORNL); Unterberg, Ezekial A [ORNL; Evans, T. E. [General Atomics, San Diego; Hillis, Donald Lee [ORNL; Maingi, R. [Oak Ridge National Laboratory (ORNL)



Crystal structure and temperature-dependent fluorescent property of a 2D cadmium (II) complex based on 3,6-dibromobenzene-1,2,4,5-tetracarboxylic acid  

NASA Astrophysics Data System (ADS)

A new cadmium (II) organic coordination polymers [Cd(dbtec)0.5(H2O)3]·H2O (1), has been constructed based on 3,6-dibromobenzene-1,2,4,5-tetracarboxylic acid (H4dbtec), and characterized by elemental analysis (EA), infrared spectroscopy (IR), powder X-ray diffraction (PXRD), and single crystal X-ray diffraction. In 1, ?2-?1:?1 and ?4-?2:?2 dbtec ligands link four hepta-coordinated CdII ions to form a 2D 44 topological layer structure, which is further connected into an interesting 3D network by hydrogen bond and Br\\ctdot O halogen bond. Moreover, the thermal stabilities, solid ultraviolet spectroscopy and temperature-dependent fluorescent properties of 1 were investigated.

Zhang, Liang-Liang; Guo, Yu; Wei, Yan-Hui; Guo, Jie; Wang, Xing-Po; Sun, Dao-Feng



Cobalt 60 and proton radiation effects on large format, 2-D, CCD arrays for an earth imaging application  

NASA Astrophysics Data System (ADS)

Cobalt 60 and 10-MeV proton irradiations have been carried out on n-buried channel frame transfer CCDs (charge coupled devices) in order to study changes in charge transfer efficiency (CTE) and dark current for room temperature, 1 microsec/pixel, readout conditions. Bias dependence and postannealing effects were observed for ionization damage. CTE effects are explained in terms of capture and emission from deep level traps. Temporal instabilities (random telegraph signals) were observed in the proton-induced dark current.

Hopkinson, G. R.



Reconstruction of 3D lung models from 2D planning data sets for Hodgkin's lymphoma patients using combined deformable image registration and navigator channels  

SciTech Connect

Purpose: Late complications (cardiac toxicities, secondary lung, and breast cancer) remain a significant concern in the radiation treatment of Hodgkin's lymphoma (HL). To address this issue, predictive dose-risk models could potentially be used to estimate radiotherapy-related late toxicities. This study investigates the use of deformable image registration (DIR) and navigator channels (NCs) to reconstruct 3D lung models from 2D radiographic planning images, in order to retrospectively calculate the treatment dose exposure to HL patients treated with 2D planning, which are now experiencing late effects. Methods: Three-dimensional planning CT images of 52 current HL patients were acquired. 12 image sets were used to construct a male and a female population lung model. 23 ''Reference'' images were used to generate lung deformation adaptation templates, constructed by deforming the population model into each patient-specific lung geometry using a biomechanical-based DIR algorithm, MORFEUS. 17 ''Test'' patients were used to test the accuracy of the reconstruction technique by adapting existing templates using 2D digitally reconstructed radiographs. The adaptation process included three steps. First, a Reference patient was matched to a Test patient by thorax measurements. Second, four NCs (small regions of interest) were placed on the lung boundary to calculate 1D differences in lung edges. Third, the Reference lung model was adapted to the Test patient's lung using the 1D edge differences. The Reference-adapted Test model was then compared to the 3D lung contours of the actual Test patient by computing their percentage volume overlap (POL) and Dice coefficient. Results: The average percentage overlapping volumes and Dice coefficient expressed as a percentage between the adapted and actual Test models were found to be 89.2{+-}3.9% (Right lung=88.8%; Left lung=89.6%) and 89.3{+-}2.7% (Right=88.5%; Left=90.2%), respectively. Paired T-tests demonstrated that the volumetric reconstruction method made a statistically significant improvement to the population lung model shape (p<0.05). The error in the results were also comparable to the volume overlap difference observed between inhale and exhale lung volumes during free-breathing respiratory motion (POL:p=0.43; Dice:p=0.20), which implies that the accuracies of the reconstruction method are within breathing constraints and would not be the confining factor in estimating normal tissue dose exposure. Conclusions: The result findings show that the DIR-NC technique can achieve a high degree of reconstruction accuracy, and could be useful in approximating 3D dosimetric representations of historical 2D treatment. In turn, this could provide a better understanding of the biophysical relationship between dose-volume exposure and late term radiotherapy effects.

Ng, Angela; Nguyen, Thao-Nguyen; Moseley, Joanne L.; Hodgson, David C.; Sharpe, Michael B.; Brock, Kristy K. [Radiation Medicine Program, Princess Margaret Hospital, University Health Network, Toronto, Ontario M5G 2M9 (Canada); Department of Medical Biophysics, University of Toronto, Toronto, Ontario M5G 2M9 (Canada); Radiation Medicine Program, Princess Margaret Hospital, University Health Network, Toronto, Ontario M5G 2M9 (Canada); Radiation Medicine Program, Princess Margaret Hospital, University Health Network, Toronto, Ontario M5G 2M9, Canada and Department of Radiation Oncology, University of Toronto, Toronto, Ontario M5G 2M9 (Canada); Radiation Medicine Program, Princess Margaret Hospital, University Health Network, Toronto, Ontario M5G 2M9 (Canada); Department of Medical Biophysics, University of Toronto, Toronto, Ontario M5G 2M9 (Canada) and Department of Radiation Oncology, University of Toronto, Toronto, Ontario M5G 2M9 (Canada)



Collisions of slow hydrocarbon ions CD4+, CD5+, C2D4+, and C2H5+ with room temperature and heated tungsten surfaces  

NASA Astrophysics Data System (ADS)

The interaction of selected hydrocarbon ions with tungsten surfaces, at room temperature and heated to 600 °C, was investigated at incident energies of 15-45 eV and at incident angles of 60° and 45° to the surface normal. Results were compared with earlier published studies on carbon (highly oriented pyrolytic graphite, HOPG) surfaces. The ion survival probability for both room temperature and heated W surfaces was in general a factor of 2-15 smaller than on carbon (HOPG) surfaces and tended to be smaller for radical cations (CD4+ and C2D4+) than for closed-shell ions (CD5+ and C2H5+). Mass spectra, translational energy distributions and angular distributions of product ions from collisions with W surfaces were very similar to distributions estimated earlier for carbon (HOPG) surfaces. Mass spectra of radical cations on room temperature surfaces indicated fragmentation of projectile ions and reactions (of H-atom transfer and carbon-chain build-up) with hydrocarbons on the surface. Closed-shell ions showed only fragmentation processes. On heated surfaces, only fragmentations of the incident projectile ions were observed. The similarity of results on heated tungsten and HOPG surfaces may be due to substantial coverage of W surfaces with tungsten carbides originating from cracked surface hydrocarbons.

Pysanenko, Andriy; Zabka, Jan; Märk, Tilmann D.; Herman, Zdenek



Fast and Robust 2D-Shape Extraction Using Discrete-Point Sampling and Centerline Grouping in Complex Images.  


This paper initially develops the discrete-point sampling operator's concept, model, and parameters that we have previously proposed, and makes its belt-shaped regions in a discrete-point sampling map more salient and appropriate for centerline extraction. The cross-sectional features of these belt-shaped regions are then analyzed and seven types of feature points are defined to facilitate descriptions of such features. Based on these feature points, a three-level detection system is proposed, including feature points, line segments, and centerlines, to extract centerlines from the belt-shaped regions. Eight basic types of centerlines and five types of relationships among the centerlines are defined by computational geometry algorithms, and Gestalt laws are used to cluster them into groupings. If some prior information about a desired shape is available, retrieval grouping may be carried out by a discrete-point sampling map, the purpose of which is to find centerlines by best matching with prior information. Discrete-point sampling effectually overcomes the influences of interference from noise, textures, and uneven illumination, and greatly reduces the difficulty of centerline extraction. Centerline clustered groupings and retrieval grouping can offer a strong anti-interference ability with nonlinear deformations such as articulation and occlusion. This method can extract large-scale complex shapes combined of lines and planes from complex images. The wheel location results of noise test and other shape extraction experiments show that our method has a strong capability to persist with nonlinear deformations. PMID:23955758

Zhu, Zongxiao; Wang, Guoyou; Liu, Jianguo; Chen, Zhong



Real-time intensity-based rigid 2d-3d medical image registration using RapidMind Multi-core Development Platform.  


In this paper, we present an efficient intensity-based rigid 2D-3D image registration method. We implement the algorithm using the RapidMind Multi-core Development Platform(1) to exploit the highly parallel multi-core architecture of graphics processing units (GPUs). We use a ray casting algorithm to generate the digitally reconstructed radiographs (DRRs) on GPUs and efficiently reduce the complexity of DRR construction. The registration optimization problem is solved by the Gauss-Newton method. To fully exploit the multi-core parallelism, we implement almost the entire registration process in parallel by RapidMind. We also discuss the RapidMind implementation of the major computation steps. Numerical results are presented to demonstrate the efficiency of our method. PMID:19163934

Xu, Lin; Wan, Justin W L



Diversity of atrial local Ca2+ signalling: evidence from 2-D confocal imaging in Ca2+-buffered rat atrial myocytes.  


Atrial myocytes, lacking t-tubules, have two functionally separate groups of ryanodine receptors (RyRs): those at the periphery colocalized with dihydropyridine receptors (DHPRs), and those at the cell interior not associated with DHPRs. We have previously shown that the Ca(2+) current (I(Ca))-gated central Ca(2+) release has a fast component that is followed by a slower and delayed rising phase. The mechanisms that regulate the central Ca(2+) releases remain poorly understood. The fast central release component is highly resistant to dialysed Ca(2+) buffers, while the slower, delayed component is completely suppressed by such exogenous buffers. Here we used dialysis of Ca(2+) buffers (EGTA) into voltage-clamped rat atrial myocytes to isolate the fast component of central Ca(2+) release and examine its properties using rapid (240 Hz) two-dimensional confocal Ca(2+) imaging. We found two populations of rat atrial myocytes with respect to the ratio of central to peripheral Ca(2+) release (R(c/p)). In one population ('group 1', approximately 60% of cells), R(c/p) converged on 0.2, while in another population ('group 2', approximately 40%), R(c/p) had a Gaussian distribution with a mean value of 0.625. The fast central release component of group 2 cells appeared to result from in-focus Ca(2+) sparks on activation of I(Ca). In group 1 cells intracellular membranes associated with t-tubular structures were never seen using short exposures to membrane dyes. In most of the group 2 cells, a faint intracellular membrane staining was observed. Quantification of caffeine-releasable Ca(2+) pools consistently showed larger central Ca(2+) stores in group 2 and larger peripheral stores in group 1 cells. The R(c/p) was larger at more positive and negative voltages in group 1 cells. In contrast, in group 2 cells, the R(c/p) was constant at all voltages. In group 1 cells the gain of peripheral Ca(2+) release sites (Delta[Ca(2+)]/I(Ca)) was larger at -30 than at +20 mV, but significantly dampened at the central sites. On the other hand, the gains of peripheral and central Ca(2+) releases in group 2 cells showed no voltage dependence. Surprisingly, the voltage dependence of the fast central release component was bell-shaped and similar to that of I(Ca) in both cell groups. Removal of extracellular Ca(2+) or application of Ni(2+) (5 mM) suppressed equally I(Ca) and Ca(2+) release from the central release sites at +60 mV. Depolarization to +100 mV, where I(Ca) is absent and the Na(+)-Ca(2+) exchanger (NCX) acts in reverse mode, did not trigger the fast central Ca(2+) releases in either group, but brief reduction of [Na(+)](o) to levels equivalent to [Na(+)](i) facilitated fast peripheral and central Ca(2+) releases in group 2 myocytes, but not in group 1 myocytes. In group 2 cells, long-lasting (> 1 min) exposures to caffeine (10 mM) or ryanodine (20 microM) significantly suppressed I(Ca)-triggered central and peripheral Ca(2+) releases. Our data suggest significant diversity of local Ca(2+) signalling in rat atrial myocytes. In one group, I(Ca)-triggered peripheral Ca(2+) release propagates into the interior triggering central Ca(2+) release with significant delay. In a second group of myocytes I(Ca) triggers a significant number of central sites as rapidly and effectively as the peripheral sites, thereby producing more synchronized Ca(2+) releases throughout the myocytes. The possible presence of vestigial t-tubules and larger Ca(2+) content of central sarcoplasmic reticulum (SR) in group 2 cells may be responsible for the rapid and strong activation of central release of Ca(2+) in this subset of atrial myocytes. PMID:16020459

Woo, Sun-Hee; Cleemann, Lars; Morad, Martin



Effective incorporating spatial information in a mutual information based 3D-2D registration of a CT volume to X-ray images.  


This paper addresses the problem of estimating the 3D rigid poses of a CT volume of an object from its 2D X-ray projection(s). We use maximization of mutual information, an accurate similarity measure for multi-modal and mono-modal image registration tasks. However, it is known that the standard mutual information measures only take intensity values into account without considering spatial information and their robustness is questionable. In this paper, instead of directly maximizing mutual information, we propose to use a variational approximation derived from the Kullback-Leibler bound. Spatial information is then incorporated into this variational approximation using a Markov random field model. The newly derived similarity measure has a least-squares form and can be effectively minimized by a multi-resolution Levenberg-Marquardt optimizer. Experiments were conducted on datasets from two applications: (a) intra-operative patient pose estimation from a limited number (e.g. 2) of calibrated fluoroscopic images, and (b) post-operative cup orientation estimation from a single standard X-ray radiograph with/without gonadal shielding. The experiment on intra-operative patient pose estimation showed a mean target registration accuracy of 0.8mm and a capture range of 11.5mm, while the experiment on estimating the post-operative cup orientation from a single X-ray radiograph showed a mean accuracy below 2 degrees for both anteversion and inclination. More importantly, results from both experiments demonstrated that the newly derived similarity measures were robust to occlusions in the X-ray image(s). PMID:20413268

Zheng, Guoyan



[A new 2D and 3D imaging approach to musculoskeletal physiology and pathology with low-dose radiation and the standing position: the EOS system].  


Close collaboration between multidisciplinary specialists (physicists, biomecanical engineers, medical radiologists and pediatric orthopedic surgeons) has led to the development of a new low-dose radiation device named EOS. EOS has three main advantages: The use of a gaseous X-ray detector, invented by Georges Charpak (Nobel Prizewinner 1992), the dose necessary to obtain a 2D image of the skeletal system has been reduced by 8 to 10 times, while that required to obtain a 3D reconstruction from CT slices has fallen by a factor of 800 to 1000. The accuracy of the 3D reconstruction obtained with EOS is as good as that obtained with CT. The patient is examined in the standing (or seated) position, and is scanned simultaneously from head to feet, both frontally and laterally. This is a major advantage over conventional CT which requires the patient to be placed horizontally. -The 3D reconstructions of each element of the osteo-articular system are as precise as those obtained by conventional CT. EOS is also rapid, taking only 15 to 30 minutes to image the entire spine. PMID:16114859

Dubousset, Jean; Charpak, Georges; Dorion, Irène; Skalli, Wafa; Lavaste, François; Deguise, Jacques; Kalifa, Gabriel; Ferey, Solène




SciTech Connect

The evolution of 2-D emission profiles of D{sub {alpha}} and C III during type-I ELMs has been investigated in DIII-D using a tangentially viewing gated, intensified charge-injected device (CID) camera. The measured CIII emission profiles indicate transient inner leg attachment with the arrival of the ELM heat pulse. The measured D{sub {alpha}} emission profiles during an ELM cycle show enhanced deuterium recycling during the deposition of the ELM particle pulse at the target, which suggests the detachment of the divertor plasma from the target plates. Measurements taken in ELMy H-mode discharges at densities of 50% and 90% of the Greenwald density limit are compared utilizing the CID camera system and a comprehensive set of other divertor diagnostics. An ELM model based on fluid and PIC simulations is used to discuss the observation on the response of the divertor plasma to the ELM heat and particle pulse.




Description and demonstration of the new Middle and Upper atmosphere Radar imaging system: 1-D, 2-D, and 3-D imaging of troposphere and stratosphere  

NASA Astrophysics Data System (ADS)

The Middle and Upper atmosphere Radar (MUR) was upgraded in March 2004 for radar imaging capability with 5 frequencies across a 1 MHz bandwidth and 25 digital receivers. Although digitization introduces problems of its own, the uniformity of digitization is a great benefit over the analogue system in place before. This increased reliability will help make the new system an important component of long-term atmospheric science programs. We demonstrate 3-D imaging with Capon's method, which can provide information about structure morphology. In addition, we demonstrate an experimental 0.5 ?s pulse mode and compare this to Capon method imaging results.

Hassenpflug, G.; Yamamoto, M.; Luce, H.; Fukao, S.



Stream Temperature Estimation From Thermal Infrared Images  

NASA Astrophysics Data System (ADS)

Stream temperature is an important water quality indicator in the Pacific Northwest where endangered fish populations are sensitive to elevated water temperature. Cold water refugia are essential for the survival of threatened salmon when events such as the removal of riparian vegetation result in elevated stream temperatures. Regional assessment of stream temperatures is limited by sparse sampling of temperatures in both space and time. If critical watersheds are to be properly managed it is necessary to have spatially extensive temperature measurements of known accuracy. Remotely sensed thermal infrared (TIR) imagery can be used to derive spatially distributed estimates of the skin temperature (top 100 nm) of streams. TIR imagery has long been used to estimate skin temperatures of the ocean, where split-window techniques have been used to compensate for atmospheric affects. Streams are a more complex environment because 1) most are unresolved in typical TIR images, and 2) the near-bank environment of stream corridors may consist of tall trees or hot rocks and soils that irradiate the stream surface. As well as compensating for atmospheric effects, key problems to solve in estimating stream temperatures include both subpixel unmixing and multiple scattering. Additionally, fine resolution characteristics of the stream surface such as evaporative cooling due to wind, and water surface roughness, will effect measurements of radiant skin temperatures with TIR devices. We apply these corrections across the Green River and Yakima River watersheds in Washington State to assess the accuracy of remotely sensed stream surface temperature estimates made using fine resolution TIR imagery from a ground-based sensor (FLIR), medium resolution data from the airborne MASTER sensor, and coarse-resolution data from the Terra-ASTER satellite. We use linear spectral mixture analysis to isolate the fraction of land-leaving radiance originating from unresolved streams. To compensate the data for atmospheric effects we combine radiosonde profiles with a physically based radiative transfer model (MODTRAN) and an in-scene relative correction adapted from the ISAC algorithm. Laboratory values for water emissivities are used as a baseline estimate of stream emissivities. Emitted radiance reflected by trees in the stream near-bank environment is estimated from the height and canopy temperature, using a radiosity model.

Handcock, R. N.; Kay, J. E.; Gillespie, A.; Naveh, N.; Cherkauer, K. A.; Burges, S. J.; Booth, D. B.



Development of a soft-X ray detector for energy resolved 2D imaging by means of a Gas Pixel Detector with highly integrated microelectronics  

NASA Astrophysics Data System (ADS)

Soft-X ray 2-D imaging on ITER is not considered yet. We propose a new approach, based on a gas detector with a gas electron multiplier (GEM) as amplifying structure and with a two-dimensional readout fully integrated with the front end electronics, through an ASIC developed on purpose. The concept has been already tested by means of a prototype, with 128 pixels, carried out in Frascati in collaboration with INFN-Pisa and tested on FTU in 2001 and NSTX in 2002-2004. Thanks to the photon counting mode, it provides 2-D imaging with high time resolution (sub millisecond), high sensitivity and signal to noise ratio. Its capability of energy discrimination allows the acquisition of pictures in X-ray energy bands or to perform a spectral scan in the full energy interval. We propose the realisation of such kind a detector with a readout microchip (ASIC) equipped with 105600 hexagonal pixels arranged at 70 ?m pitch in a 300×352 honeycomb matrix, corresponding to an active area of 2.1×2.1 cm2, with a pixel density of 240 pixels/ mm2. Each pixel is connected to a charge sensitive amplifier followed by a discriminator of pulse amplitude and counter. The chip integrates more than 16.5 million transistors and it is subdivided in 64 identical clusters, to be read independently each other. An important part of the work will be also the design of the whole detector to fulfil all the constraints and requirements as plasma diagnostic in a tokamak machine. Since the detector has high and controllable intrinsic gain, it works well even at very low photon energy, ranging from 0.2 keV to 10 keV (X-VUV region). This range appears therefore particularly suitable for ITER to monitor the outer part of the plasma. In particular pedestal physics, edge modes, localization and effects of additional heating, boundary plasma control etc. The capability of this proposed detector to work in this energy range is further valuable because solid state detectors are not favorite at low energy because of the lack of intrinsic gain.

Pacella, D.; Romano, A.; Pizzicaroli, G.; Gabellieri, L.; Bellazzini, R.; Brez, A.



Development of a soft-X ray detector for energy resolved 2D imaging by means of a Gas Pixel Detector with highly integrated microelectronics  

SciTech Connect

Soft-X ray 2-D imaging on ITER is not considered yet. We propose a new approach, based on a gas detector with a gas electron multiplier (GEM) as amplifying structure and with a two-dimensional readout fully integrated with the front end electronics, through an ASIC developed on purpose. The concept has been already tested by means of a prototype, with 128 pixels, carried out in Frascati in collaboration with INFN-Pisa and tested on FTU in 2001 and NSTX in 2002-2004. Thanks to the photon counting mode, it provides 2-D imaging with high time resolution (sub millisecond), high sensitivity and signal to noise ratio. Its capability of energy discrimination allows the acquisition of pictures in X-ray energy bands or to perform a spectral scan in the full energy interval. We propose the realisation of such kind a detector with a readout microchip (ASIC) equipped with 105600 hexagonal pixels arranged at 70 {mu}m pitch in a 300x352 honeycomb matrix, corresponding to an active area of 2.1x2.1 cm{sup 2}, with a pixel density of 240 pixels/ mm{sup 2}. Each pixel is connected to a charge sensitive amplifier followed by a discriminator of pulse amplitude and counter. The chip integrates more than 16.5 million transistors and it is subdivided in 64 identical clusters, to be read independently each other. An important part of the work will be also the design of the whole detector to fulfil all the constraints and requirements as plasma diagnostic in a tokamak machine. Since the detector has high and controllable intrinsic gain, it works well even at very low photon energy, ranging from 0.2 keV to 10 keV (X-VUV region). This range appears therefore particularly suitable for ITER to monitor the outer part of the plasma. In particular pedestal physics, edge modes, localization and effects of additional heating, boundary plasma control etc. The capability of this proposed detector to work in this energy range is further valuable because solid state detectors are not favorite at low energy because of the lack of intrinsic gain.

Pacella, D.; Pizzicaroli, G. [Associazione Euratom-ENEA sulla Fusione, Frascati (Italy); Romano, A.; Gabellieri, L.; Bellazzini, R.; Brez, A. [Istituto Nazionale Fisica Nucleare, Pisa (Italy)



A novel material detection algorithm based on 2D GMM-based power density function and image detail addition scheme in dual energy X-ray images.  


Material detection is a vital need in dual energy X-ray luggage inspection systems at security of airport and strategic places. In this paper, a novel material detection algorithm based on statistical trainable models using 2-Dimensional power density function (PDF) of three material categories in dual energy X-ray images is proposed. In this algorithm, the PDF of each material category as a statistical model is estimated from transmission measurement values of low and high energy X-ray images by Gaussian Mixture Models (GMM). Material label of each pixel of object is determined based on dependency probability of its transmission measurement values in the low and high energy to PDF of three material categories (metallic, organic and mixed materials). The performance of material detection algorithm is improved by a maximum voting scheme in a neighborhood of image as a post-processing stage. Using two background removing and denoising stages, high and low energy X-ray images are enhanced as a pre-processing procedure. For improving the discrimination capability of the proposed material detection algorithm, the details of the low and high energy X-ray images are added to constructed color image which includes three colors (orange, blue and green) for representing the organic, metallic and mixed materials. The proposed algorithm is evaluated on real images that had been captured from a commercial dual energy X-ray luggage inspection system. The obtained results show that the proposed algorithm is effective and operative in detection of the metallic, organic and mixed materials with acceptable accuracy. PMID:22635176

Pourghassem, Hossein



2D and 3D Electrical Resistivity Tomography imaging of earthquake related ground deformations at the Ancient Roman Forum and Isis Temple of Baelo Claudia (Cádiz, South Spain).  

NASA Astrophysics Data System (ADS)

The ancient roman city of Baelo Claudia has been subject of several papers on earthquake environmental effects (EEE) and well as earthquake archaeological effects (EAE). During the field training course on archaeoseismology and palaeoseismology conducted in September 2009 (INQUA-IGCP567 Workshop) held at Baelo Claudia, four Electric Resistivity Tomography (ERT) profiles were carried out, by the teams of the Salamanca University (Spain), RWTH Aachen University (Germany) and the Geological Survey of Spain (IGME). ERT surveys were developed in the eastern side of the ancient roman Forum across the unexcavated sector of the archaeological site heading on the 1st Century AD Isis Temple. Each ERT profile was constituted by a 48 multielectrode array with spacing of 2 m resulting in a total length of investigation of around 384 m. ERT lines were separated 10 m each other resulting in a total research area of 3840 m2 to a mean investigation depth of 16 m. The selected survey configurations were Pole-Dipole and Wenner in order to get detailed information about lateral resistivity contrasts, but with a reasonable depth of investigation. The resulting 2D resistivity pseudosections clearly display deformations of the buried roman pavements which propagated in depth within the pre-roman clayey substratum of the Bolonia Bay area.. 3D modelling of the 2D pseudosections indicates that the observed deformations are related to near-surface landsliding, being possible to calculate the minimum volume of mobilized material. ERT 3D imaging allow to refine previous GPR surveys conducted at this same area and to get a subsurface picture of ground deformations caused by repeated earthquakes during the 1st and 3rd Centuries AD. Preliminary calculated volume for the mobilized materials affecting the foundations of the Isis Temple and Forum clearly points to a minimum ESI-07 VIII Intensity validating previous research in the zone. This study has been supported by the Spanish Research Projects ACI2008-0276 (USAL), CGL08-03998BTE (USAL), CGL08-04000BTE (MNCN, CSIC)

Silva, Pablo G.



Spectrally edited 2D 13C13C NMR spectra without diagonal ridge for characterizing 13C-enriched low-temperature carbon materials  

NASA Astrophysics Data System (ADS)

Two robust combinations of spectral editing techniques with 2D 13C13C NMR have been developed for characterizing the aromatic components of 13C-enriched low-temperature carbon materials. One method (exchange with protonated and nonprotonated spectral editing, EXPANSE) selects cross peaks of protonated and nearby nonprotonated carbons, while the other technique, dipolar-dephased double-quantum/single-quantum (DQ/SQ) NMR, selects signals of bonded nonprotonated carbons. Both spectra are free of a diagonal ridge, which has many advantages: Cross peaks on the diagonal or of small intensity can be detected, and residual spinning sidebands or truncation artifacts associated with the diagonal ridge are avoided. In the DQ/SQ experiment, dipolar dephasing of the double-quantum coherence removes protonated-carbon signals; this approach also eliminates the need for high-power proton decoupling. The initial magnetization is generated with minimal fluctuation by combining direct polarization, cross polarization, and equilibration by 13C spin diffusion. The dipolar dephased DQ/SQ spectrum shows signals from all linkages between aromatic rings, including a distinctive peak from polycondensed aromatics. In EXPANSE NMR, signals of protonated carbons are selected in the first spectral dimension by short cross polarization combined with dipolar dephasing difference. This removes ambiguities of peak assignment to overlapping signals of nonprotonated and protonated aromatic carbons, e.g. near 125 ppm. Spin diffusion is enhanced by dipolar-assisted rotational resonance. Before detection, CH dipolar dephasing by gated decoupling is applied, which selects signals of nonprotonated carbons. Thus, only cross peaks due to magnetization originating from protonated C and ending on nearby nonprotonated C are retained. Combined with the chemical shifts deduced from the cross-peak position, this double spectral editing defines the bonding environment of aromatic, COO, and CO carbons, which is particularly useful for identifying furan and arene rings. The CO carbons, whose chemical shifts vary strongly (between 212 and 165 ppm) and systematically depend on their two bonding partners, show particularly informative cross peaks, given that one bonding partner is defined by the other frequency coordinate of the cross peak. The new techniques and the information content of the resulting spectra are validated on sulfuric-acid treated low-temperature carbon materials and on products of the Maillard reaction. The crucial need for spectral editing for correct peak assignment is demonstrated in an example.

Johnson, Robert L.; Anderson, Jason M.; Shanks, Brent H.; Fang, Xiaowen; Hong, Mei; Schmidt-Rohr, Klaus



Tubular anisotropy for 2D vessel segmentation  

Microsoft Academic Search

In this paper, we present a new approach for segmentation of tubular structures in 2D images providing minimal interaction. The main objective is to extract centerlines and boundaries of the vessels at the same time. The first step is to represent the trajectory of the vessel not as a 2D curve but to go up a dimension and represent the

Fethallah Benmansour; Laurent D. Cohen; M. Law; A. Chung



Tubular anisotropy for 2D vessel segmentation  

Microsoft Academic Search

In this paper, we present a new approach for segmenta- tion of tubular structures in 2D images providing minimal interaction. The main objective is to extract centerlines and boundaries of the vessels at the same time. The first step is to represent the trajectory of the vessel not as a 2D curve but to go up a dimension and represent

Fethallah Benmansour; Laurent D. Cohen; Max W. K. Law; Albert Chung



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.

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



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


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



Application of infrared thermal imaging in blade system temperature monitoring  

Microsoft Academic Search

All objects emit infrared radiation at differing levels, depending on their temperature. Infrared thermal imaging is the technique of producing an image from infrared radiation. This thermal image represents two-dimensional distribution of the infrared radiation emitted by object displaying the object's temperatures. High performance computing data centres deploy high-density blade servers that have high power and cooling requirements. Thermal management

Darko Kolaric; Tomislav Lipic; Ivan Grubisic; Luko Gjenero; Karolj Skala



Quantified Temperature Effect in a CMOS Image Sensor  

Microsoft Academic Search

In recent years, CMOS image sensors (CISs) have increasingly become major players in the solid-state imaging market, a market in which charge-coupled device image sensors were once the dominant product. Exceptional circuit integration capability makes CMOS imagers suitable for implementation in a single-chip imaging system while inducing the temperature variation of an image sensor. In this paper, global and local

Dong-Long Lin; Ching-Chun Wang; Chia-Ling Wei



2D and 3D Prestack Depth Migration Seismic Imaging around NanTroSEIZE LWD sites as a mission for the IODP Implementing Organization  

Microsoft Academic Search

Since 1997, 2D seismic sections were acquired across the Nankai Trough by IFREE\\/JAMSTEC. Based on these crustal structure studies for site survey purposes, the NanTroSEIZE drilling plan has been solidified. In 2003, CDEX acquired an additional commercial 2D MCS survey of closely spaced, high resolution. We used a single 4240 in3 source and a 6000 m streamer. The purpose of

Y. Kido; Y. Sanada; S. Uraki; S. Kuaramoto; Y. Kawamura; G. F. Moore; C. Gr; E. Party



Non-invasive ultrasound-based temperature imaging for monitoring radiofrequency heating—phantom results  

NASA Astrophysics Data System (ADS)

Minimally invasive therapies (such as radiofrequency ablation) are becoming more commonly used in the United States for the treatment of hepatocellular carcinomas and liver metastases. Unfortunately, these procedures suffer from high recurrence rates of hepatocellular carcinoma (~34-55%) or metastases following ablation therapy. The ability to perform real-time temperature imaging while a patient is undergoing radiofrequency ablation could provide a significant reduction in these recurrence rates. In this paper, we demonstrate the feasibility of ultrasound-based temperature imaging on a tissue-mimicking phantom undergoing radiofrequency heating. Ultrasound echo signals undergo time shifts with increasing temperature, which are tracked using 2D correlation-based speckle tracking methods. Time shifts or displacements in the echo signal are accumulated, and the gradient of these time shifts are related to changes in the temperature of the tissue-mimicking phantom material using a calibration curve generated from experimental data. A tissue-mimicking phantom was developed that can undergo repeated radiofrequency heating procedures. Both sound speed and thermal expansion changes of the tissue-mimicking material were measured experimentally and utilized to generate the calibration curve relating temperature to the displacement gradient. Temperature maps were obtained, and specific regions-of-interest on the temperature maps were compared to invasive temperatures obtained using fiber-optic temperature probes at the same location. Temperature elevation during a radiofrequency ablation procedure on the phantom was successfully tracked to within ±0.5 °C.

Daniels, M. J.; Varghese, T.; Madsen, E. L.; Zagzebski, J. A.



Effects of Frozen Soil on Soil Temperature, Spring Infiltration, and Runoff: Results from the PILPS 2(d) Experiment at Valdai, Russia  

Microsoft Academic Search

The Project for Intercomparison of Land-Surface Parameterization Schemes phase 2(d) experiment at Valdai, Russia, offers a unique opportunity to evaluate land surface schemes, especially snow and frozen soil parameterizations. Here, the ability of the 21 schemes that participated in the experiment to correctly simulate the thermal and hydrological properties of the soil on several different timescales was examined. Using observed

Lifeng Luo; Alan Robock; Konstantin Y. Vinnikov; C. Adam Schlosser; Andrew G. Slater; Aaron Boone; Harald Braden; Peter Cox; Patricia de Rosnay; Robert E. Dickinson; Yongjiu Dai; Qingyun Duan; Pierre Etchevers; Ann Henderson-Sellers; Nicola Gedney; Yevgeniy M. Gusev; Florence Habets; Jinwon Kim; Eva Kowalczyk; Kenneth Mitchell; Olga N. Nasonova; Joel Noilhan; Andrew J. Pitman; John Schaake; Andrey B. Shmakin; Tatiana G. Smirnova; Peter Wetzel; Yongkang Xue; Zong-Liang Yang; Qing-Cun Zeng



PIV, 2D-LIF and 1D-Raman measurements of flow field, composition and temperature in premixed gas turbine flames  

SciTech Connect

Several laser diagnostic measurement techniques have been applied to study the lean premixed natural gas/air flames of an industrial swirl burner. This was made possible by equipping the burner with an optical combustion chamber that was installed in the high-pressure test rig facility at the DLR Institute of Combustion Technology in Stuttgart. The burner was operated with preheated air at various operating conditions with pressures up to p = 6 bar and a maximum thermal power of P = 1 MW. The instantaneous planar flow field inside the combustor was studied with particle image velocimetry (PIV). Planar laser induced fluorescence (PLIF) of OH radicals on a single-shot basis was used to determine the shape and the location of the flame front as well as the spatial distribution of reaction products. 1D laser Raman spectroscopy was successfully applied for the measurement of the temperature and the concentration of major species under realistic gas turbine conditions. Results of the flow field analysis show the shape and the size of the main flow regimes: the inflow region, the inner and the outer recirculation zone. The highly turbulent flow field of the inner shear layer is found to be dominated by small and medium sized vortices. High RMS fluctuations of the flow velocity in the exhaust gas indicate the existence of a rotating exhaust gas swirl. From the PLIF images it is seen that the primary reactions happened in the shear layers between inflow and the recirculation zones and that the appearance of the reaction zones changed with flame parameters. The results of the multiscalar Raman measurements show a strong variation of the local mixture fraction allowing conclusions to be drawn about the premix quality. Furthermore, mixing effects of unburnt fuel and air with fully reacted combustion products are studied giving insights into the processes of the turbulence-chemistry interaction. (author)

Stopper, U.; Aigner, M.; Ax, H.; Meier, W.; Sadanandan, R.; Stoehr, M. [German Aerospace Center (DLR), Institute of Combustion Technology, Pfaffenwaldring 38-40, D-70569 Stuttgart (Germany); Bonaldo, A. [Siemens Industrial Turbomachinery Ltd., Combustion Group, P. O. Box 1, Waterside South, Lincoln LN5 7FD (United Kingdom)



Temperature sensitivity of Cu K(alpha) imaging efficiency using a spherical Bragg reflecting crystal  

SciTech Connect

The Vulcan laser facility at the Rutherford Appleton Laboratory was used to study the interaction of a 75 J 10 ps, high intensity laser beam with low-mass solid, Cu targets. Two instruments were fielded as diagnostics of the Cu K-shell emission from the targets: A single photon counting CCD spectrometer provided the absolute K{sub {alpha}} yield and a spherically bent Bragg crystal recorded 2D monochromatic images with a spatial resolution of 10 {micro}m. Due to the shifting and broadening of the K{sub {alpha}} spectral lines with increasing temperature, there is a temperature dependence of the crystal collection efficiency. This provides a temperature diagnostic when cross calibrated against a single hit CCD spectrometer, and it affects measurements of the spatial pattern of electron transport. The experimental data showing changing collection efficiency are presented. The results are discussed in light of modeling of the temperature-dependent spectrum of Cu K-shell emission.

Akli, K U; Key, M H; Chung, H K; Hansen, S B; Freeman, R R; Chen, M H; Gregori, G; Hatchett, S; Hey, D; Izumi, N; King, J A; Kuba, J; Norreys, P; Mackinnon, A J; Murphy, C D; Snavely, R; Stepehens, R; Stoeckel, C; Theobald, W; Zhang, B



Absolute temperature imaging using intermolecular multiple quantum MRI  

PubMed Central

Purpose A review of MRI temperature imaging methods based on intermolecular multiple quantum coherences (iMQCs) is presented. Temperature imaging based on iMQCs can provide absolute temperature maps that circumvent the artefacts that other proton frequency shift techniques suffer from such as distortions to the detected temperature due to susceptibility changes and magnetic field inhomogeneities. Thermometry based on iMQCs is promising in high-fat tissues such as the breast, since it relies on the fat signal as an internal reference. This review covers the theoretical background of iMQCs, and the necessary adaptations for temperature imaging using iMQCs. Materials and methods Data is presented from several papers on iMQC temperature imaging. These studies were done at 7T in both phantoms and in vivo. Results from phantoms of cream (homogeneous mixture of water and fat) are presented as well as in vivo temperature maps in obese mice. Results Thermometry based on iMQCs offers the potential to provide temperature maps which are free of artefacts due to susceptibility and magnetic field inhomogeneities, and detect temperature on an absolute scale. Conclusions The data presented in the papers reviewed highlights the promise of iMQC-based temperature imaging in fatty tissues such as the breast. The change in susceptibility of fat with temperature makes standard proton frequency shift methods (even with fat suppression) challenging and iMQC-based imaging offers an alternative approach.




Minimum resolvable temperature difference measurements on undersampled imagers  

Microsoft Academic Search

Minimum Resolvable Temperature Difference (MRTD) is the primary measurement of performance for infrared imaging systems. Where Modulation Transfer Function (MTF) is a measurement of resolution and three-dimensional noise (or noise equivalent temperature difference) is a measurement of sensitivity, MRTD combines both measurements into a test of observer visual acuity through the imager. MRTD has been incorrectly applied to undersampled thermal

Ronald G. Driggers; Van A. Hodgkin; Richard H. Vollmerhausen; Patrick O'Shea



Studying the effect of noise on the performance of 2D and 3D texture measures for quantifying the trabecular bone structure as obtained with high resolution MR imaging at 3 tesla  

NASA Astrophysics Data System (ADS)

3.0 Tesla MRI devices are becoming popular in clinical applications since they render images with a higher signal-tonoise ratio than the former 1.5 Tesla MRI devices. Here, we investigate if higher signal-to-noise ratio can be beneficial for a quantitative image analysis in the context of bone research. We performed a detailed analysis of the effect of noise on the performance of 2D morphometric linear measures and a 3D nonlinear measure with respect to their correlation with biomechanical properties of the bone expressed by the maximum compressive strength. The performance of both 2D and 3D texture measures was relatively insensitive to superimposed artificial noise. This finding suggests that MR sequences for visualizing bone structures at 3T should rather be optimized to spatial resolution (or scanning time) than to signal-to-noise ratio.

Monetti, Roberto; Bauer, Jan; Mueller, Dirk; Rummeny, Ernst J.; Link, Thomas M.; Majumdar, Sharmila; Matsuura, Maiko; Eckstein, Felix; Sidorenko, Irina; Raeth, Christoph W.



3D-2D phase transition in vortex lattice of layered high-temperature superconductors of BSCCO (Bi$_{1.7}$Pb$_{0.3}$Sr$_2$Ca$_2$Cu$_3$O$_4$)  

Microsoft Academic Search

Using the high-sensitive mechanical method of measuring the dissipation\\u000aprocesses in superconductors, the 3D-2D phase transition in magnetic field was\\u000ainvestigated in the vortex lattice of strongly anisotropic high-temperature\\u000asuperconductors of Bi(2223) system. It was shown that with the increase of\\u000aexternal magnetic field the dissipation connected with a motion of vortexes\\u000arelative to the crystal lattice of a sample,

J. G. Chigvinadze; A. A. Iashvili; T. V. Machaidze



Velocity Measurements in the Middle Cerebral Arteries of Healthy Volunteers Using 3D Radial Phase-Contrast HYPRFlow: Comparison with Transcranial Doppler Sonography and 2D Phase-Contrast MR Imaging  

PubMed Central

BACKGROUND AND PURPOSE We have developed PC HYPRFlow, a comprehensive MRA technique that includes a whole-brain CE dynamic series followed by PC velocity-encoding, yielding a time series of high-resolution morphologic angiograms with associated velocity information. In this study, we present velocity data acquired by using the PC component of PC HYPRFlow (PC-VIPR). MATERIALS AND METHODS Ten healthy volunteers (6 women, 4 men) were scanned by using PC HYPRFlow and 2D-PC imaging, immediately followed by velocity measurements by using TCD. Velocity measurements were made in the M1 segments of the MCAs from the PC-VIPR, 2D-PC, and TCD examinations. RESULTS PC-VIPR showed approximately 30% lower mean velocity compared with TCD, consistent with other comparisons of TCD with PC-MRA. The correlation with TCD was r = 0.793, and the correlation of PC-VIPR with 2D-PC was r = 0.723. CONCLUSIONS PC-VIPR is a technique capable of acquiring high-resolution MRA of diagnostic quality with velocity data comparable with TCD and 2D-PC. The combination of velocity information and fast high-resolution whole-brain morphologic angiograms makes PC HYPRFlow an attractive alternative to current MRA methods.

Chang, W.; Landgraf, B.; Johnson, K.M.; Kecskemeti, S.; Wu, Y.; Velikina, J.; Rowley, H.; Wieben, O.; Mistretta, C.; Turski, P.



Robust object detection using marginal space learning and ranking-based multi-detector aggregation: Application to left ventricle detection in 2D MRI images  

Microsoft Academic Search

Magnetic resonance imaging (MRI) is currently the gold standard for left ventricle (LV) quantification. Detection of the LV in an MRI image is a prerequisite for functional measurement. However, due to the large variations in the orientation, size, shape, and image intensity of the LV, automatic LV detection is challenging. In this paper, we propose to use marginal space learning

Yefeng Zheng; Xiaoguang Lu; Bogdan Georgescu; Arne Littmann; Edgar Mueller; Dorin Comaniciu



Infrared imaging of temperature distribution in a high-temperature x-ray diffraction furnace  

Microsoft Academic Search

High Temperature X-ray Diffraction (HTXRD) is a very powerful tool for studies of reaction kinetics, phase transformations, and lattice thermal expansion of advanced materials. Accurate temperature measurement is a critical part of the technique. Traditionally, thermocouples, thermisters, and optical pyrometers have been used for temperature control and measurement, and temperature could only be measured at a single point. Infrared imaging

Hsin Wang; E. A. Payzant



Digital autoradiography using room temperature CCD and CMOS imaging technology.  


CCD (charged coupled device) and CMOS imaging technologies can be applied to thin tissue autoradiography as potential imaging alternatives to using conventional film. In this work, we compare two particular devices: a CCD operating in slow scan mode and a CMOS-based active pixel sensor, operating at near video rates. Both imaging sensors have been operated at room temperature using direct irradiation with images produced from calibrated microscales and radiolabelled tissue samples. We also compare these digital image sensor technologies with the use of conventional film. We show comparative results obtained with (14)C calibrated microscales and (35)S radiolabelled tissue sections. We also present the first results of (3)H images produced under direct irradiation of a CCD sensor operating at room temperature. Compared to film, silicon-based imaging technologies exhibit enhanced sensitivity, dynamic range and linearity. PMID:17671349

Cabello, Jorge; Bailey, Alexis; Kitchen, Ian; Prydderch, Mark; Clark, Andy; Turchetta, Renato; Wells, Kevin



Detection of ash fusion temperatures based on the image processing  

NASA Astrophysics Data System (ADS)

The detection of ash fusion temperatures is important in the research of coal characteristics. The prevalent method is to build up ash cone with some dimension and detect the characteristic temperatures according to the morphological change. However, conditional detection work is not accurate and brings high intensity of labor as a result of both visualization and real-time observation. According to the insufficiency of conventional method, a new method to determine ash fusion temperatures with image processing techniques is introduced in this paper. Seven techniques (image cutting, image sharpening, edge picking, open operation, dilate operation, close operation, geometrical property extraction) are used in image processing program. The processing results show that image sharpening can intensify the outline of ash cone; Prewitt operator may extract the edge well among many operators; mathematical morphology of image can filter noise effectively while filling up the crack brought by filtration, which is useful for further disposal; characteristic temperatures of ash fusion temperatures can be measured by depth-to-width ratio. Ash fusion temperatures derived from this method match normal values well, which proves that this method is feasible in detection of ash fusion temperatures.

Li, Peisheng; Yue, Yanan; Hu, Yi; Li, Jie; Yu, Wan; Yang, Jun; Hu, Niansu; Yang, Guolu



Simultaneous 2-D Imaging Measurements of Reaction Progress Variable and OH Radical Concentration in Turbulent Premixed Flames: Experimental Methods and Flame Brush Structure  

Microsoft Academic Search

Experimental methods are detailed for comprehensive further investigation of the turbulent premixed flames of natural-gas\\/air mixtures stabilized on a Bunsen-type burner already studied by joint imaging of OH and velocity (Franker, 1999). Simultaneous two-dimensional measurements of reaction progress variable and OH mole fraction are made from planar imaging of Rayleigh scattering and laser-induced fluorescence of OH. Image in-plane and




Study of a method for 2-D imaging of simple-shaped targets with arbitrary motion using UWB radar with a small number of antennas  

Microsoft Academic Search

Ultra-wideband (UWB) pulse radar is an effective device as the basis for building a high-precision surveillance system. The fast SEABED (Shape Estimation Algorithm based on BST and Extraction of Directly scattered waves) imaging algorithm is capable of accurately estimating target shapes using UWB pulse radar. A new UWB radar imaging algorithm, based on an extension of the SEABED algorithm that

Yuji Matsuki; Takuya Sakamoto; Toru Sato



Photoacoustic imaging and temperature measurement for photothermal cancer therapy  

PubMed Central

Photothermal therapy is a noninvasive, targeted, laser-based technique for cancer treatment. During photothermal therapy, light energy is converted to heat by tumor-specific photoabsorbers. The corresponding temperature rise causes localized cancer destruction. For effective treatment, however, the presence of photoabsorbers in the tumor must be ascertained before therapy and thermal imaging must be performed during therapy. This study investigates the feasibility of guiding photothermal therapy by using photoacoustic imaging to detect photoabsorbers and to monitor temperature elevation. Photothermal therapy is carried out by utilizing a continuous wave laser and metal nanocomposites broadly absorbing in the near-infrared optical range. A linear array-based ultrasound imaging system is interfaced with a nanosecond pulsed laser to image tissue-mimicking phantoms and ex-vivo animal tissue before and during photothermal therapy. Before commencing therapy, photoacoustic imaging identifies the presence and spatial location of nanoparticles. Thermal maps are computed by monitoring temperature-induced changes in the photoacoustic signal during the therapeutic procedure and are compared with temperature estimates obtained from ultrasound imaging. The results of our study suggest that photoacoustic imaging, augmented by ultrasound imaging, is a viable candidate to guide photoabsorber-enhanced photothermal therapy.

Shah, Jignesh; Park, Suhyun; Aglyamov, Salavat; Larson, Timothy; Ma, Li; Sokolov, Konstantin; Johnston, Keith; Milner, Thomas; Emelianov, Stanislav Y.



Lectures on 2D gravity and 2D string theory  

Microsoft Academic Search

This report discusses the following topics: loops and states in conformal field theory; brief review of the Liouville theory; 2D Euclidean quantum gravity 1 -- path integral approach; 2D Euclidean quantum gravity 2 -- canonical approach; states in 2D string theory; matrix model technology 1 -- method of orthogonal polynomials; matrix model technology 2 -- loops on the lattice; matrix

P. Ginsparg; Gregory Moore



Development and Implementation of a Web-Enabled 3D Consultation Tool for Breast Augmentation Surgery Based on 3D-Image Reconstruction of 2D Pictures  

PubMed Central

Background Producing a rich, personalized Web-based consultation tool for plastic surgeons and patients is challenging. Objective (1) To develop a computer tool that allows individual reconstruction and simulation of 3-dimensional (3D) soft tissue from ordinary digital photos of breasts, (2) to implement a Web-based, worldwide-accessible preoperative surgical planning platform for plastic surgeons, and (3) to validate this tool through a quality control analysis by comparing 3D laser scans of the patients with the 3D reconstructions with this tool from original 2-dimensional (2D) pictures of the same patients. Methods The proposed system uses well-established 2D digital photos for reconstruction into a 3D torso, which is then available to the user for interactive planning. The simulation is performed on dedicated servers, accessible via Internet. It allows the surgeon, together with the patient, to previsualize the impact of the proposed breast augmentation directly during the consultation before a surgery is decided upon. We retrospectively conduced a quality control assessment of available anonymized pre- and postoperative 2D digital photographs of patients undergoing breast augmentation procedures. The method presented above was used to reconstruct 3D pictures from 2D digital pictures. We used a laser scanner capable of generating a highly accurate surface model of the patient’s anatomy to acquire ground truth data. The quality of the computed 3D reconstructions was compared with the ground truth data used to perform both qualitative and quantitative evaluations. Results We evaluated the system on 11 clinical cases for surface reconstructions and 4 clinical cases of postoperative simulations, using laser surface scan technologies showing a mean reconstruction error between 2 and 4 mm and a maximum outlier error of 16 mm. Qualitative and quantitative analyses from plastic surgeons demonstrate the potential of these new emerging technologies. Conclusions We tested our tool for 3D, Web-based, patient-specific consultation in the clinical scenario of breast augmentation. This example shows that the current state of development allows for creation of responsive and effective Web-based, 3D medical tools, even with highly complex and time-consuming computation, by off-loading them to a dedicated high-performance data center. The efficient combination of advanced technologies, based on analysis and understanding of human anatomy and physiology, will allow the development of further Web-based reconstruction and predictive interfaces at different scales of the human body. The consultation tool presented herein exemplifies the potential of combining advancements in the core areas of computer science and biomedical engineering with the evolving areas of Web technologies. We are confident that future developments based on a multidisciplinary approach will further pave the way toward personalized Web-enabled medicine.

Garcia, Jaime; Olariu, Radu; Dindoyal, Irving; Le Huu, Serge



Stellar Aberration 2D  

NSDL National Science Digital Library

The Stellar Aberration 2D Model illustrates the phenomenon known as the aberration of starlight, first reported by James Bradley in 1729. Aberration occurs because light has a finite speed, and thus light from a star takes a finite amount of time to travel through the tube of a telescope. During this time, the telescope moves as a result of Earth's rotational and orbital motions (in this case, the orbital motion is more important because it is faster). Therefore, if the telescope is pointed directly at the star the starlight will hit the sides of the tube before reaching the eyepiece. To see the star the telescope must be pointed forward (i.e. in the direction of Earth's motion) very slightly. The simulation shows a telescope (depicted as a red rectangle) and a star (white point) directly overhead. When the simulation is run a pulse of light is emitted from the star and travels straight downward to Earth. The telescope moves to the right due to Earth's motion. As a result, if the telescope is pointed straight up (ie toward the actual location of the star) the pulse of light will not reach the bottom of the telescope. Controls allow the user to set the speed of Earth and the tilt of the telescope. The user can modify the tilt until the starlight reaches the bottom of the telescope. Alternately, the user can use the Options menu to set the telescope to the correct tilt for the current speed setting.

Timberlake, Todd



First single-crystal synthesis and low-temperature structural determination of the quasi-2D quantum spin compound (CuCl)LaNb2O7.  


We provide a full description of the first single-crystal synthesis of the low-dimensional quantum spin compound (CuCl)LaNb(2)O(7) through the low-temperature topotactic ion exchange route. Very fast diffusion of ion-exchanged CuCl and Cs ions is observed. In addition, thorough structure determination at very low temperature is outlined following use of single-crystal X-ray diffraction and powder neutron diffraction, taking advantage of the better sensitivity of the latter method for describing O and Cl atoms. State-of-the-art calculations (Maximum Entropy Method) are used for visualising the fine structural features of this unusual pseudo-tetragonal superstructure. Our study unambiguously throws light on the long-standing controversy concerning the crystal structure of this compound, and allows for a relevant description of its magnetic properties. Incidentally, it is demonstrated that the low-temperature structural model tentatively proposed very recently by Tsirlin et al. (Phys. Rev. B, 2010, 82, 054107), according to powder synchrotron X-ray diffraction, is correct. PMID:21442114

Hernandez, Olivier J; Tassel, Cédric; Nakano, Kunihiro; Paulus, Werner; Ritter, Clemens; Collet, Eric; Kitada, Atsushi; Yoshimura, Kazuyoshi; Kageyama, Hiroshi



Support Vector Machines and CASGM20 Parameters Applied to Morphological Classification of Reconstructed 2D Images of Extended Objects Within the ESA-Gaia Mission  

NASA Astrophysics Data System (ADS)

In this work we present some parameters that are being studied to perform a purely morphological analysis of reconstructed images of extended objects, particularly galaxies, in the context of the ESA-Gaia mission. Those parameters, known as Concentration, Asymmetry, Clumpiness, Gini's coefficient and the Momentum of the brightest 20% of the galaxy, form a set that is becoming commonly used when a limited number of pixels is available to analyse, such as will be the case for Gaia reconstructed images. We comment about small modifications on those parameters that are planned to be performed. We also report tests with a preliminar version of the code that is being written to analyse Gaia images on a sample based on the Frei catalog of galaxies. Finally, we comment on the possibility of using Support Vector Machines to perform the morphological classification based on those measured parameters, and conclude that a very good level of segregation can be obtained for a two-class discrimination.

Krone-Martins, Alberto; Ducourant, Christine; Teixeira, Ramachrisna



Ternary Recombination of H3+ and D3+ with Electrons in He-H2 (D2) Plasmas at Temperatures from 50 to 300 K  

NASA Astrophysics Data System (ADS)

We present results of plasma afterglow experiments on ternary electron-ion recombination rate coefficients of H3+ and D3+ ions at temperatures from 50 to 300 K and compare them to possible three-body reaction mechanisms. Resonant electron capture into H3* Rydberg states is likely to be the first step in the ternary recombination, rather than third-body-assisted capture. Subsequent interactions of the Rydberg molecules with ambient neutral and charged particles provide the rate-limiting step that completes the recombination. A semiquantitative model is proposed that reconciles several previously discrepant experimental observations. A rigorous treatment of the problem will require additional theoretical work and experimental investigations.

Johnsen, R.; Rubovi?, P.; Dohnal, P.; Hejduk, M.; Plašil, R.; Glosík, J.



2D focusing with an off-axis elliptical Bragg-Fresnel multilayer lens and application to X-ray imaging  

Microsoft Academic Search

We demonstrate the design, the fabrication and use of an off-axis elliptical Bragg-Fresnel multilayer lens to produce a focal spot of zero-order background. We describe here the principle of these new focusing optics and its first utilization on the X-ray synchrotron beam at LURE (Orsay, France). Imaging tests of a binary object at 1750 eV using the third-order diffraction of

M. Idir; A. Mirone; G. Soullie; Ph. Guerin; Fr. Ladan; P. Dhez



2-D High Resolution Seismic Imaging and Potential-Field Modeling of Small-Scale Intrabasin Faulting in Surprise Valley, California  

NASA Astrophysics Data System (ADS)

Surprise Valley, located in the northeast corner of California, constitutes the westernmost basin of the Basin and Range Province (BRP) and acts as a transition zone between the unextended Cenozoic volcanic rocks of the Modoc Plateau to the west and the extended BRP to the east. Previous seismic experiments undertaken in Surprise Valley to examine the structural setting of a developing extensional basin imaged the Surprise Valley Fault (SVF), the large-scale structure that controls the basin formation. In this study, we image small-scale structures associated with a prominent N-S-trending magnetic anomaly in the basin; these small-scale structures have no surface expression, yet they presumably play a role in the active geothermal system in the valley and may lend insight into the development of the basin. We recorded a total of 198 shots fired between geophones on a fixed linear array spanning ~ 1 km using a Betsy Seisgun source. The source yielded excellent penetration depths of up to 400 m, presumably due to the ideal conditions of fine-grained lake deposits saturated almost immediately below the surface. We used a standard seismic processing sequence to create an unmigrated time section, but lack of velocity control at depth led to the creation of a suite of different migrated images to explore the effects of strong lateral velocity variations in the subsurface. . Images obtained by applying Kirchhoff pre-stack depth migration to the seismic data reveal what we interpret to be an east-dipping (~56°) normal fault offsetting tilted strata of probable Oligocene age with ~250 meters of vertical throw. In addition to the 1 km seismic line, detailed gravity and magnetic surveys were undertaken to fully image the structure(s) north and south of the seismic line. The magnetic survey was performed with a cesium vapor total-field magnetometer installed on our newly developed all-terrain vehicle (ATV) magnetometer system, which was designed for efficient surveying in desert environments. The ATV’s induced magnetic field is accounted for by a heading correction, similar to that used in aeromagnetic surveys, and the overall noise level of the system is ~ 4 nT. We collected ~ 300 km of magnetic data in 2 days, imaging a 400 nT N-S-trending magnetic high. Modeling of the potential-field data confirms the interpretation of the seismic data of a buried east-dipping normal fault. Future potential-field modeling will look at whether this tectonic model can be applied north of the seismic line where the magnetic anomaly broadens significantly or whether an intrusive body is necessary, signaling contemporaneous volcanic activity with faulting. The outcome of our study validates our strategy of rapid potential-field profiling over large areas to identify specific targets for more intensive and expensive seismic profiles, the interpretation of which can be validated by detailed potential-field modeling.

Athens, N.; Fontiveros, V. C.; Klemperer, S. L.; Egger, A. E.; Glen, J. M.



Photoacoustic imaging and temperature measurement for photothermal cancer therapy  

Microsoft Academic Search

Photothermal therapy is a noninvasive, targeted, laser- based technique for cancer treatment. During photothermal therapy, light energy is converted to heat by tumor-specific photoabsorbers. The corresponding temperature rise causes localized cancer destruc- tion. For effective treatment, however, the presence of photoabsorbers in the tumor must be ascertained before therapy and thermal imaging must be performed during therapy. This study investigates

Jignesh Shah; Salavat Aglyamov; Timothy Larson; Li Ma; Konstantin Sokolov; Keith Johnston; Thomas Milner; Stanislav Y. Emelianov



Accurate Temperature Imaging Based on Intermolecular Coherences in Magnetic Resonance  

PubMed Central

Conventional magnetic resonance methods that provide interior temperature profiles, which find use in clinical applications such as hyperthermic therapy, can develop inaccuracies caused by the inherently inhomogeneous magnetic field within tissues or by probe dynamics, and work poorly in important applications such as fatty tissues. We present a magnetic resonance method that is suitable for imaging temperature in a wide range of environments. It uses the inherently sharp resonances of intermolecular zero-quantum coherences, in this case flipping up a water spin while flipping down a nearby fat spin. We show that this method can rapidly and accurately assign temperatures in vivo on an absolute scale.

Galiana, Gigi; Branca, Rosa T.; Jenista, Elizabeth R.; Warren, Warren S.



Enabling NIR imaging at room temperature using quantum dots  

NASA Astrophysics Data System (ADS)

Imaging in visible light at room temperature is now a well-mastered technology, whereas imaging in the near infrared (NIR) remains a challenge. NIR imaging has many applications like sensing, night vision and biological diagnostics. Unfortunately, silicon detectors are inefficient above 1000 nm, and other IR technologies still need low working temperatures and are thus expensive. Colloidal quantum dots can overcome these limitations thanks to their absorption wavelength tunability depending on their chemical composition and size. After a brief review of this research field, we will present the preparation of hybrid photodetectors using NIR absorbing PbS quantum dots in combination with poly(3-hexylthiopene) and PCBM. We discuss different solution based deposition processes for device fabrication (spincoating, dip-coating, doctor blading, inkjet printing). Preliminary device tests result in a detectivity of 4.7.109 Jones at 1300 nm.

Le Calvez, S.; Bourvon, H.; Kanaan, H.; Meunier-Della Gatta, S.; Philippot, C.; Reiss, P.



EJS 2D-Ising Model  

NSDL National Science Digital Library

The EJS 2D Ising model displays a lattice of spins. You can change the lattice size, temperature, and external magnetic field. You can modify this simulation if you have Ejs installed by right-clicking within the plot and selecting âOpen Ejs Modelâ from the pop-up menu item. The 2D-Ising model was created using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_stp_Ising2D.jar file will run the program if Java is installed. Ejs is a part of the Open Source Physics Project and is designed to make it easier to access, modify, and generate computer models. Additional Ejs models are available. They can be found by searching ComPADRE for Open Source Physics, OSP, or Ejs.

Christian, Wolfgang



Infrared imaging of temperature distribution in a high-temperature x-ray diffraction furnace  

NASA Astrophysics Data System (ADS)

High Temperature X-ray Diffraction (HTXRD) is a very powerful tool for studies of reaction kinetics, phase transformations, and lattice thermal expansion of advanced materials. Accurate temperature measurement is a critical part of the technique. Traditionally, thermocouples, thermisters, and optical pyrometers have been used for temperature control and measurement, and temperature could only be measured at a single point. Infrared imaging was utilized in this study to characterize the thermal gradients resulting from various sample and furnace configurations in a commercial strip heater furnace. Furnace configurations include a metallic strip heater, with and without a secondary surround heater, or surround heater alone. Sample configurations include low and high thermal conductivity powders and solids. The IR imaging results have been used to calibrate sample temperatures in the HTXRD furnace.

Wang, Hsin; Payzant, E. A.



Infrared Imaging of Temperature Distribution in a High Temperature X-Ray Diffraction Furnace  

SciTech Connect

High Temperature X-ray Diffraction (HTXRD) is a very powerful tool for studies of reaction kinetics, phase transformations, and lattice thermal expansion of advanced materials. Accurate temperature measurement is a critical part of the technique. Traditionally, thermocouples, thermistors, and optical pyrometers have been used for temperature control and measurement and temperature could only be measured at a single point. Infrared imaging was utilized in this study to characterize the thermal gradients resulting from various sample and furnace configurations in a commercial strip heater furnace. Furnace configurations include a metallic strip heater, with and without a secondary surround heater, or a surround heater alone. Sample configurations include low and high thermal conductivity powders and solids. The IR imaging results have been used to calibrate sample temperatures in the HTXRD furnace.

Payzant, E.A.; Wang, H.



Lectures on 2D gravity and 2D string theory  

SciTech Connect

This report the following topics: loops and states in conformal field theory; brief review of the Liouville theory; 2D Euclidean quantum gravity I: path integral approach; 2D Euclidean quantum gravity II: canonical approach; states in 2D string theory; matrix model technology I: method of orthogonal polynomials; matrix model technology II: loops on the lattice; matrix model technology III: free fermions from the lattice; loops and states in matrix model quantum gravity; loops and states in the C=1 matrix model; 6V model fermi sea dynamics and collective field theory; and string scattering in two spacetime dimensions.

Ginsparg, P. (Los Alamos National Lab., NM (United States)); Moore, G. (Yale Univ., New Haven, CT (United States). Dept. of Physics)



Volumetric PIV and 2D OH PLIF imaging in the far-field of a low Reynolds number nonpremixed jet flame  

NASA Astrophysics Data System (ADS)

Cinematographic stereoscopic PIV with temporal and spatial resolution ranging from 2.6 to 5.5 Kolmogorov scales, which is sufficient to accurately represent most of the dissipation structures, is used in conjunction with Taylor’s frozen flow hypothesis to generate quasi-instantaneous pseudo-volumes of the three-component velocity field in the far-field of a nonpremixed jet flame at the jet exit Reynolds number (Red) of 8000. The 3D data enable the computation of the nine components of the velocity gradient tensor and other important kinematic quantities. The volumetric PIV is combined with single-shot simultaneous OH PLIF imaging to mark the instantaneous reaction zone at one plane in the reconstructed volume. The combined datasets enable the investigation of the relationship between the reaction zone and the fully-3D representations of strain, vorticity, kinetic energy dissipation and dilatation, and of the impact of heat release on the structure of turbulence. In this Red = 8000 flame, it is observed that sheet-like layers of vorticity and dissipation tend to coincide and are aligned with the OH layers, an effect that is believed to be due to the stabilizing effect of heat release on this relatively low Reynolds number jet flame. Furthermore, the spatial organization of the strain field is predominantly driven by the presence of the flame rather than turbulence. Finally, intense dissipation is mostly due to the laminar shear caused by the presence of the flame rather than to the strain generated by vortical structures as typically observed in nonreacting jets.

Gamba, M.; Clemens, N. T.; Ezekoye, O. A.



Flower structures and Riedel shears at a step over zone along the Alpine Fault (New Zealand) inferred from 2-D and 3-D GPR images  

NASA Astrophysics Data System (ADS)

High-resolution GPS and ground-penetrating radar (GPR) data are used to detect and identify hidden faults along a stretch of the transpressional Alpine Fault (South Island, New Zealand) immediately north of its junction with the Hope Fault. At this location, the Alpine Fault emerges from the basement into a sequence of variably thick late Holocene gravel deposits. Geomorphology and trenching already mapped three principal fault strands and two distinct step over zones at the study site. Our GPR images reveal numerous additional secondary fault strands throughout the region, only some of which are obvious at the surface or in the trench walls. According to the GPR data, the main fault-generated disturbance zone has a width ranging from ˜40 to ˜200 m. The secondary fault strands outside of the step over zones likely represent the branches of positive flower structures, whereas the faulting pattern around the step over zones is best explained in terms of linked Riedel shears. Systematic northeastward increases in the width of the main fault-generated disturbance zone and corresponding increases in principal fault-scarp height are the likely consequences of older terraces in the northeast being disrupted and offset by more earthquakes than younger terraces in the southwest. The pattern of complex faulting in this region is distinct from the system of alternating strike-slip and reverse faults characteristic of the Alpine Fault to the south and from the rather simple sequence of faults mapped to the north. GPR surveying has added new information on the distribution and nature of faulting at our study site.

Carpentier, S. F. A.; Green, A. G.; Langridge, R.; Boschetti, S.; Doetsch, J.; AbäCherli, A. N.; Horstmeyer, H.; Finnemore, M.



Imaging of broadband terahertz beams using an array of antenna-coupled microbolometers operating at room temperature.  


We present results of 2D real-time imaging of terahertz (THz) beam generated by a photoconductive antenna driven by a femtosecond oscillator. The detector, operating at room temperature, is a 320 x 240 array of antenna-coupled microbolometers with integrated CMOS read-out electronics delivering 25 images per second. High quality images of broadband THz beams covering the 0.1-2 THz range are recorded while maintaining a signal-to-noise ratio of 10 for detected THz power as low as 25 nW. The compactness of the easy-to-use uncooled camera makes it very useful for the alignment of systems such as THz time-domain spectrometers and for the characterization of emitters, optics and other components. PMID:23482016

Oden, Jonathan; Meilhan, Jérome; Lalanne-Dera, Jérémy; Roux, Jean-François; Garet, Frédéric; Coutaz, Jean-Louis; Simoens, François



2-D fiberoptic scanning microdisplay system  

NASA Astrophysics Data System (ADS)

This paper details the improvement of image quality of the previously developed piezoelectric driven 2D Optical Display system using an optical fiber waveguide. The current display system is able to produce a desired image (FPGA input) via the oscillation of a micro-fabricated cantilever waveguide or an optical fiber "pixel" driven by two piezoelectric actuators in perpendicular arrangements; however, the image produced is blurred and unstable. To sharpen the image and allow a more detailed image to be displayed, a more refined output "pixel" is needed. To obtain such a "pixel", optical fibers with a tapered tip and metallic deposits is to be used on the output end. The use of the tapered fiber as a waveguide reduces the light that was being misguided by the cladding of the fiber and produces a finer "pixel" at each point of the image, reducing the blurriness of the displayed image. A closed loop feedback control was also added because the existing system requires manual frequency calibration to find the proper frequency to display the image after each system reset. The added control will find the proper frequency by matching the input image and the output image via image recognition coding in MATLAB and adjust the system to the optimal display frequency at the initialization of the system.

Wang, Wei-Chih; Tsui, Chi-Leung; Lau, Fai-Hon; Perez, Alex; Chuang, Wei-Ching



A method for the retrieval of atomic oxygen density and temperature profiles from ground-based measurements of the O sup + ( sup 2 D minus sup 2 P) 7320- angstrom twilight airglow  

SciTech Connect

This paper describes a technique for the retrieval of altitude profiles of the atomic oxygen concentration (n = (O)) and temperature (T) from ground-based measurements of the {sup +}O({sup 2}D{minus}{sup 2}P) doublet at 7,320 and 7,330 {angstrom} in the twilight airglow. The technique is based on previously demonstrated knowledge that at solar zenith angles (SZA) characteristic of twilight conditions, the upper state of the 7,320-{angstrom} doublet transition is produced by photoionization and photoelectron impact ionization of atomic oxygen and lost mainly by radiative decay, thereby providing a sensitive dependence on (O). The authors apply inverse problem theory to retrieve the exospheric temperature T{sub {infinity}}, the atomic oxygen concentration at 120 km (n{sub 120}), the temperature at 120 km (T{sub 120}) and the temperature profile shape factor (S) using a Bates-Walker representation of n. The algorithm is tested and theoretically verified using synthetic data sets where random errors of measurements are characterized by Poisson noise due primarily to sky background. In the tests that they report here, the solar EUV flux is specified. By comparing retrieved with known input values, it is demonstrated that for the altitude range 200 to 500 km the atomic oxygen concentration (O) can be retrieved with relative errors {plus minus} 15% and systematic errors of about 25% if the solar EUV is given. Sensitivity of the results to noise, sample size (degrees of freedom), and absolute calibration are quantitatively evaluated. In addition, to demonstrate the validity of the technique experimentally, they utilized the Atmosphere Explorer E (AE-E) in situ measurements of the solar EUV flux and (O), with the latter taken when perigee was over Arecibo on an occasion when the observatory airglow spectrometer was simultaneously measuring the 7320-{angstrom} emission from the ground during twilight.

Fennelly, J.A.; Torr, D.G.; Richards, P.G. (Univ. of Alabama, Huntsville (USA)); Torr, M.R. (NASA Marshall Space Flight Center, Huntsville, AL (USA)); Sharp, W.E. (Univ. of Michigan, Ann Arbor (USA))



Random Walk 2D Model  

NSDL National Science Digital Library

The EJS Random Walk 2D Model simulates a 2-D random walk. You can change the number of walkers and probability of going a given direction. You can modify this simulation if you have Ejs installed by right-clicking within the plot and selecting âOpen Ejs Modelâ from the pop-up menu item. The Random Walk 2D Model was created using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_stp_RandomWalk2D.jar file will run the program if Java is installed. Ejs is a part of the Open Source Physics Project and is designed to make it easier to access, modify, and generate computer models. Additional Ejs models are available. They can be found by searching ComPADRE for Open Source Physics, OSP, or Ejs.

Christian, Wolfgang



2D NMR Metabonomic Analysis  

PubMed Central

Motivation Comparative metabolic profiling by nuclear magnetic resonance (NMR) is showing increasing promise for identifying inter-individual differences to drug response. Two dimensional (2D) 1H-13C NMR can reduce spectral overlap, a common problem of 1D 1H NMR. However, the peak alignment tools for 1D NMR spectra are not well suited for 2D NMR. An automated and statistically robust method for aligning 2D NMR peaks is required to enable comparative metabonomic analysis using 2D NMR. Results A novel statistical method was developed to align NMR peaks that represent the same chemical groups across multiple 2D NMR spectra. The degree of local pattern match among peaks in different spectra is assessed using a similarity measure, and a heuristic algorithm maximizes the similarity measure for peaks across the whole spectrum. This peak alignment method was used to align peaks in 2D NMR spectra of endogenous metabolites in liver extracts obtained from four inbred mouse strains in the study of acetaminophen-induced liver toxicity. This automated alignment method was validated by manual examination of the top fifty peaks as ranked by signal intensity. Manual inspection of 1872 peaks in 39 different spectra demonstrated that the automated algorithm correctly aligned 1810 (96.7%) peaks. Availability Algorithm is available upon request. Contact

Zheng, Ming; Lu, Peng; Liu, Yanzhou; Pease, Joseph; Usuka, Jonathan; Liao, Guochun; Peltz, Gary



Terahertz imaging of excised oral cancer at frozen temperature  

PubMed Central

The feasibility of terahertz (THz) imaging at frozen temperature for the clinical application of oral cancer detection was investigated by analyzing seven oral tissues resected from four patients. The size, shape, and internal position of the oral cancers were mapped by THz radiation in the frequency range of 0.2–1.2 THz at ?20 °C and 20 °C, and compared with those identified in the histological examination. THz imaging of frozen tissue was found to offer greater sensitivity in distinguishing cancerous areas from surrounding tissue and a larger THz-frequency spectral difference between the oral cancer and normal mucosa than room-temperature THz imaging. A cancerous tumor hidden inside tissue was also detected using this method by observing the THz temporal domain waveform. The histological analysis showed that these findings resulted from cell structure deformations involving the invasion of oral tumor and neoplastic transformations of mucous cells. Therefore, a cytological approach using THz radiation at a frozen temperature might be applied to detect oral cancer.

Sim, Yookyeong Carolyn; Park, Jae Yeon; Ahn, Kang-Min; Park, Chansik; Son, Joo-Hiuk



MAGNUM-2D computer code: user's guide  

SciTech Connect

Information relevant to the general use of the MAGNUM-2D computer code is presented. This computer code was developed for the purpose of modeling (i.e., simulating) the thermal and hydraulic conditions in the vicinity of a waste package emplaced in a deep geologic repository. The MAGNUM-2D computer computes (1) the temperature field surrounding the waste package as a function of the heat generation rate of the nuclear waste and thermal properties of the basalt and (2) the hydraulic head distribution and associated groundwater flow fields as a function of the temperature gradients and hydraulic properties of the basalt. MAGNUM-2D is a two-dimensional numerical model for transient or steady-state analysis of coupled heat transfer and groundwater flow in a fractured porous medium. The governing equations consist of a set of coupled, quasi-linear partial differential equations that are solved using a Galerkin finite-element technique. A Newton-Raphson algorithm is embedded in the Galerkin functional to formulate the problem in terms of the incremental changes in the dependent variables. Both triangular and quadrilateral finite elements are used to represent the continuum portions of the spatial domain. Line elements may be used to represent discrete conduits. 18 refs., 4 figs., 1 tab.

England, R.L.; Kline, N.W.; Ekblad, K.J.; Baca, R.G.



How reliable is Zeeman Doppler imaging without simultaneous temperature reconstruction?  

NASA Astrophysics Data System (ADS)

Context. Aims: The goal of this study is to perform numerical tests of Zeeman Doppler imaging (ZDI) to asses whether correct reconstruction of magnetic fields is at all possible without taking temperature into account for stars in which magnetic and temperature inhomogeneities are spatially correlated. Methods: We used a modern ZDI code employing a physically realistic treatment of the polarized radiative transfer in all four Stokes parameters. We generated artificial observations of isolated magnetic spots and of magnetic features coinciding with cool temperature spots and then reconstructed magnetic and temperature distributions from these data. Results: Using Stokes I and V for simultaneous magnetic and temperature mapping for the star with a homogeneous temperature distribution yields magnetic field strengths underestimated by typically 10-15% relative to their true values. When temperature is kept constant and Stokes I is not used for magnetic mapping, the underestimation is 30-60%. At the same time, the strength of magnetic field inside cool spots is underestimated by as much as 80-95% and the spot geometry is also poorly reconstructed when temperature variations are ignored. On the other hand, the inversion quality is greatly improved when temperature variations are accounted for in magnetic mapping. The field strength is underestimated by 40-70% for the radial and azimuthal spots and by 70-80% for the meridional spots. Inversions still suffer from significant crosstalk between radial and meridional fields at low latitudes. The azimuthal field component proves to be most robust since it suffers the least from crosstalk. When using all four Stokes parameters crosstalk is removed. In that case, the reconstructed field strength inside cool spots is underestimated by 30-40% but the spot geometry can be recovered very accurately compared to the experiments with circular polarization alone. Conclusions: Reliable magnetic field reconstruction for a star with high-contrast temperature spots is essentially impossible if temperature inhomogeneities are ignored. A physically realistic line profile modeling method, which simultaneously accounts for both types of inhomogeneities, is required for meaningful ZDI of cool active stars.

Rosén, L.; Kochukhov, O.



Optical correlation and convolution of real 2D inputs and real 2D filters  

NASA Astrophysics Data System (ADS)

Frequently in character recognition, there is a need to correlate or convolve purely real 2D inputs and real 2D filters. We propose two optical correlators. The first, basic real-input-real-filter optical correlator, adds x and y mirror images adjacent to the image to generate real and even images. This avoids the need for an offset reference to capture phase. Therefore, we have greater diffraction efficiency and a reduction in filter LCD pixel size. The second, Hilbert transform basic real-input-real-filter optical correlator, uses a Hilbert transform by masking in the filter plane to reduce the number elements in the filter LCD to that of the number of pixels in a filter image. An optical system can generate the mirror images in real time so that both the input LCD and the filter LCD can have only the same number of elements as their respective number of image pixels. We show how a spatial filter can be used to remove the intensity offset produced in the Hilbert transform and restore shift invariance if required. Finally, if desired, some rotation invariance can be achieved by overlapping the mirror images with the basic correlator. Advantages and disadvantages of the proposed correlators are discussed.

McAulay, Alastair D.



Extensions of 2D gravity  

SciTech Connect

After reviewing some aspects of gravity in two dimensions, I show that non-trivial embeddings of sl(2) in a semi-simple (super) Lie algebra give rise to a very large class of extensions of 2D gravity. The induced action is constructed as a gauged WZW model and an exact expression for the effective action is given.

Sevrin, A.



Turbulence in MESA-2D.  

National Technical Information Service (NTIS)

The MESA-2D Eulerian, compressible flow code has been extended to include the effects of turbulence. In this turbulence model, transport equations for the turbulent kinetic energy k, the turbulent scale s, and the turbulence mass flux components a(sub i) ...

B. Daly



2-D real time polarimetric spectrograph with 64-channel.  

NASA Astrophysics Data System (ADS)

A brief description of the multichannel birefringent filter and its three types is provided. A 2-D real time polarimetric spectrograph with 64-channel, an achromatic KD'P modulator, and an automatic supplement system for temperature change, are introduced.

Ai, Guoxiang



Bose-Einstein Condensation in Quasi2D Trapped Gases  

Microsoft Academic Search

We discuss Bose-Einstein condensation (BEC) in quasi-2D trapped gases and find that well below the transition temperature Tc the equilibrium state is a true condensate, whereas at intermediate temperatures T2D gas is sensitive to the frequency omega0 of the (tight) confinement in the ``frozen'' direction, and

D. S. Petrov; M. Holzmann; G. V. Shlyapnikov



Bose-einstein condensation in quasi-2D trapped gases  


We discuss Bose-Einstein condensation (BEC) in quasi-2D trapped gases and find that well below the transition temperature T(c) the equilibrium state is a true condensate, whereas at intermediate temperatures T2D gas is sensitive to the frequency omega(0) of the (tight) confinement in the "frozen" direction, and one can switch the sign of the interaction by changing omega(0). Variation of omega(0) can also reduce the rates of inelastic processes. This offers promising prospects for tunable BEC in trapped quasi-2D gases. PMID:11017267

Petrov; Holzmann; Shlyapnikov



High sensitivity imaging Thomson scattering for low temperature plasma  

SciTech Connect

A highly sensitive imaging Thomson scattering system was developed for low temperature (0.1-10 eV) plasma applications at the Pilot-PSI linear plasma generator. The essential parts of the diagnostic are a neodymium doped yttrium aluminum garnet laser operating at the second harmonic (532 nm), a laser beam line with a unique stray light suppression system and a detection branch consisting of a Littrow spectrometer equipped with an efficient detector based on a ''Generation III'' image intensifier combined with an intensified charged coupled device camera. The system is capable of measuring electron density and temperature profiles of a plasma column of 30 mm in diameter with a spatial resolution of 0.6 mm and an observational error of 3% in the electron density (n{sub e}) and 6% in the electron temperature (T{sub e}) at n{sub e}=4x10{sup 19} m{sup -3}. This is achievable at an accumulated laser input energy of 11 J (from 30 laser pulses at 10 Hz repetition frequency). The stray light contribution is below 9x10{sup 17} m{sup -3} in electron density equivalents by the application of a unique stray light suppression system. The amount of laser energy that is required for a n{sub e} and T{sub e} measurement is 7x10{sup 20}/n{sub e} J, which means that single shot measurements are possible for n{sub e}>2x10{sup 21} m{sup -3}.

Meiden, H. J. van der; Al, R. S.; Barth, C. J.; Donne, A. J. H.; Goedheer, W. J.; Groot, B. de; Koppers, W. R.; Pol, M. J. van de; Prins, P. R.; Shumack, A. E.; Smeets, P. H. M.; Vijvers, W. A. J.; Westerhout, J.; Wright, G. M.; Rooij, G. J. van [FOM-Institute for Plasma Physics Rijnhuizen, Association EURATOM-FOM, partner in the Trilateral Euregio Cluster, P.O. Box 1207, 3430 BE Nieuwegein (Netherlands); Engeln, R. [Eindhoven University of Technology, 5612AZ Eindhoven (Netherlands); Kleyn, A. W. [FOM-Institute for Plasma Physics Rijnhuizen, Association EURATOM-FOM, partner in the Trilateral Euregio Cluster, P.O. Box 1207, 3430 BE Nieuwegein (Netherlands); Leiden Institute of Chemistry, Leiden University, Leiden (Netherlands); Lopes Cardozo, N. J.; Schram, D. C. [FOM-Institute for Plasma Physics Rijnhuizen, Association EURATOM-FOM, partner in the Trilateral Euregio Cluster, P.O. Box 1207, 3430 BE Nieuwegein (Netherlands); Eindhoven University of Technology, 5612AZ Eindhoven (Netherlands)



Efficient framework for deformable 2D-3D registration  

NASA Astrophysics Data System (ADS)

Using 2D-3D registration it is possible to extract the body transformation between the coordinate systems of X-ray and volumetric CT images. Our initial motivation is the improvement of accuracy of external beam radiation therapy, an effective method for treating cancer, where CT data play a central role in radiation treatment planning. Rigid body transformation is used to compute the correct patient setup. The drawback of such approaches is that the rigidity assumption on the imaged object is not valid for most of the patient cases, mainly due to respiratory motion. In the present work, we address this limitation by proposing a flexible framework for deformable 2D-3D registration consisting of a learning phase incorporating 4D CT data sets and hardware accelerated free form DRR generation, 2D motion computation, and 2D-3D back projection.

Fluck, Oliver; Aharon, Shmuel; Khamene, Ali



Development of KSTAR ECE imaging system for measurement of temperature fluctuations and edge density fluctuations  

SciTech Connect

The ECE imaging (ECEI) diagnostic tested on the TEXTOR tokamak revealed the sawtooth reconnection physics in unprecedented detail, including the first observation of high-field-side crash and collective heat transport [H. K. Park, N. C. Luhmann, Jr., A. J. H. Donneet al., Phys. Rev. Lett. 96, 195003 (2006)]. An improved ECEI system capable of visualizing both high- and low-field sides simultaneously with considerably better spatial coverage has been developed for the KSTAR tokamak in order to capture the full picture of core MHD dynamics. Direct 2D imaging of other MHD phenomena such as tearing modes, edge localized modes, and even Alfven eigenmodes is expected to be feasible. Use of ECE images of the optically thin edge region to recover 2D electron density changes during L/H mode transitions is also envisioned, providing powerful information about the underlying physics. The influence of density fluctuations on optically thin ECE is discussed.

Yun, G. S.; Lee, W.; Choi, M. J.; Kim, J. B.; Park, H. K. [Pohang University of Science and Technology, Pohang, Gyungbuk 790-784 (Korea, Republic of); Domier, C. W.; Tobias, B.; Liang, T.; Kong, X.; Luhmann, N. C. Jr. [University of California, Davis, California 95616 (United States); Donne, A. J. H. [FOM Institute for Plasma Physics Rijnhuizen, 3430 BE Nieuwegein (Netherlands)



Development of KSTAR ECE imaging system for measurement of temperature fluctuations and edge density fluctuations.  


The ECE imaging (ECEI) diagnostic tested on the TEXTOR tokamak revealed the sawtooth reconnection physics in unprecedented detail, including the first observation of high-field-side crash and collective heat transport [H. K. Park, N. C. Luhmann, Jr., A. J. H. Donne? et al., Phys. Rev. Lett. 96, 195003 (2006)]. An improved ECEI system capable of visualizing both high- and low-field sides simultaneously with considerably better spatial coverage has been developed for the KSTAR tokamak in order to capture the full picture of core MHD dynamics. Direct 2D imaging of other MHD phenomena such as tearing modes, edge localized modes, and even Alfve?n eigenmodes is expected to be feasible. Use of ECE images of the optically thin edge region to recover 2D electron density changes during L/H mode transitions is also envisioned, providing powerful information about the underlying physics. The influence of density fluctuations on optically thin ECE is discussed. PMID:21033958

Yun, G S; Lee, W; Choi, M J; Kim, J B; Park, H K; Domier, C W; Tobias, B; Liang, T; Kong, X; Luhmann, N C; Donné, A J H



2D-3D face matching using CCA  

Microsoft Academic Search

In recent years, 3D face recognition has obtained much attention. Using 2D face image as probe and 3D face data as gallery is an alternative method to deal with computation complexity, expensive equipment and fussy pretreatment in 3D face recognition systems. In this paper we propose a learning based 2D-3D face matching method using the CCA to learn the mapping

Weilong Yang; Dong Yi; Zhen Lei; Jitao Sang; Stan Z. Li



2D Vessel Segmentation Using Local Adaptive Contrast Enhancement  

Microsoft Academic Search

\\u000a 2D vessel segmentation algorithms working on 2D digital subtraction angiography (DSA) images suffer from inhomogeneous contrast\\u000a agent distributions within the vessels. In this work, we present a novel semi-automatic vessel segmentation method based on\\u000a local adaptive contrast enhancement. Either a forward projected 3D centerline or a set of manual selected seed points define\\u000a the vessel branches to be segmented on

Dominik Schuldhaus; Martin Spiegel; Thomas Redel; Maria Polyanskaya; Tobias Struffert; Joachim Hornegger; Arnd Doerfler


2D-RMHD Modeling of the Dynamics of a Ne Gas Puff Z Pinch  

NASA Astrophysics Data System (ADS)

Detailed spatially resolved spectroscopic analysis of a neon gas puff Z pinch on the Weizmann 1MA generator [1,2] indicates that the radius of the K-shell regions grows to a maximum and then decreases during the radiation pulse -- the opposite of that calculated by 1D-RMHD models. Here we compare Mach2 2D-RMHD [r-z, high resolution, moving grid, non-LTE atomic populations, 3D ray trace radiation transport] simulation results to the size of the K-shell emission region as inferred from the spectroscopic analysis. In addition 2D, 3-ns time gated visible light images recorded during the neon experiments give us the opportunity to compare with the evolution of the outer pinch radius, r(z,t), as calculated by the 2D-RMHD model. Comparisons with spectroscopically inferred results and simulation results will also be made for electron and ion temperatures as well as internal energy to study the weak ion and electron temperature equilibration observed in the data.[4pt] [1] E. Kroupp, et al., PRL, 98, 115001 (2007).[0pt] [2] D. Osin, Ph.D. Thesis (2008).

Thornhill, J.; Giuliani, J.; Dasgupta, A.; Velikovich, A.; Chong, Y.; Clark, R.; Kroupp, E.; Osin, D.; Maron, Y.; Starobinets, A.; Stambulchik, E.; Fisher, V.; Bernshtam, V.; Fisher, A.; Deeney, C.



Penile cutaneous temperature in systemic sclerosis: a thermal imaging study.  


Systemic Sclerosis is a connective tissue disorder featuring vascular alterations and an immunological activation leading to a progressive and widespread fibrosis of several organs such as the skin, lung, gastrointestinal tract, heart and kidney. Moreover men with systemic sclerosis (SSc) present an increased risk of developing erectile dysfunction (ED). Recently, we evaluated the extent of penile vascular damage in sclerodermic patients using Duplex ultrasonography. The aim of this paper is to investigate whether penile thermal differences exist between sclerodermic patients and healthy controls. For this reason 10 men with SSc receiving current treatment for their disease, and 10 healthy controls were enrolled; penile thermal properties were assessed through non-contact thermal imaging (functional Infra Red Imaging fIRI); erectile function was evaluated using the sexual health inventory for men (SHIM) questionnaire. The SHIM results confirmed the presence of ED in sclerodermic patients. Baseline penile temperature in patients (32.1 +/- 1.4 degrees C) was lower than in controls (34.1 +/- 0.9 degrees C). Recovery from cooling test was seen to be faster in healthy controls than in patients, both in terms of recovery amplitude (patients 3.75 +/- 2.09 degrees C, controls 9.80 +/- 2.77 degrees C) and amplitude to time constant ratio (patients 1.21 +/- 0.64 degrees C/min, controls 1.96 +/- 0.48 degrees C/min). These results show that penile thermal abnormalities occur in almost all sclerodermic patients. Non-contact thermal imaging not only identifies thermal alterations but also clearly distinguishes between SSc patients and healthy controls and therefore could represent a valuable instrument in identifying early ED in SSc patients. PMID:17346437

Merla, A; Romani, G L; Tangherlini, A; Di Romualdo, S; Proietti, M; Rosato, E; Aversa, A; Salsano, F


Systolic arrays for 2D digital filters  

NASA Astrophysics Data System (ADS)

Systolic architectures for 2D digital filters are presented. The structures are derived directly from the transfer function. The proposed 2D systolic arrays for 2D digital filters have several advantages over the existing 2D arrays, such as modularity and use of nearest neighbor interconnections. These two features make the proposed architecture versatile and more suitable for VLSI implementation.

Aggoun, Amar



2D Gauge Field Theory  

SciTech Connect

We show from the action integral that under the assumption of longitudinal dominance and transverse confinement, QCD4 in (3+1) dimensional space-time can be approximately compactified into QCD2 in (1+1) dimensional space-time. In such a process, we find the relation between the coupling constant $g(2D)$ in QCD2 and the coupling constant $g(4D)$ in QCD4. We also show that quarks and gluons in QCD2 acquire masses as a result of the compactification.

Koshelkin, Andrey V. [Moscow Institute for Physics and Engineering, Russia; Wong, Cheuk-Yin [ORNL



Temperature and Gravity Wave Imaging Studies from South Pole, Antarctica  

NASA Astrophysics Data System (ADS)

The unique location of the South Pole station (within the polar vortex and far from any convective or orographic sources) combined with its high altitude (2900m) makes it an excellent site for investigating the dynamics and impact of mesospheric gravity waves over the Antarctic continent. Since 2010, two collocated instruments have continuously operated at this site during the Austral winter season (from mid-April to end of August): a recently developed large field of view (120°) Advanced Mesospheric Temperature Mapper (AMTM), which measures the IR (1.5?m) OH (3,1) rotational temperature and band intensity with high precision (1K in less than 1 min), and a near-IR (0.95?m) all-sky imager which provides the characteristics of the short-period gravity waves propagating over the station, including horizontal wavelength, propagation direction, observed period and phase speed. Our initial measurements have revealed a remarkably rich mesospheric wave environment containing a broad spectrum of waves, from short-period (<1h) gravity waves to planetary wave signatures. In this presentation we will describe recent results obtained over the past two winter seasons and contrast them with previous findings from other high-latitude sites.

Pautet, Pierre-Dominique; Taylor, Michael J.; Zhao, Yucheng; Hernandez, Gonzalo; McCarthy, Michael; Pendleton, William, Jr.



Measurements and Modeling of Acetone Laser-Induced Fluorescence with Implications for Temperature-Imaging Diagnostics  

Microsoft Academic Search

Recent determinations of the temperature dependence of acetone fluorescence have permitted the ap- plication of acetone planar laser-induced fluorescence imaging, which was already popular for mapping concentration, to the measurement of temperature. With a view toward developing temperature- imaging diagnostics, we present atmospheric-pressure fluorescence and absorption results acquired with excitation at eight wavelengths across the absorption feature of acetone and

Mark C. Thurber; Brian J. Kirby; Martin Votsmeier; Ronald K. Hanson



Estimation of radiative properties and temperature distributions in coal-fired boiler furnaces by a portable image processing system  

SciTech Connect

This paper presented an experimental investigation on the estimation of radiative properties and temperature distributions in a 670 t/h coal-fired boiler furnace by a portable imaging processing system. The portable system has been calibrated by a blackbody furnace. Flame temperatures and emissivities were measured by the portable system and equivalent blackbody temperatures were deduced. Comparing the equivalent blackbody temperatures measured by the portable system and the infrared pyrometer, the relative difference is less than 4%. The reconstructed pseudo-instantaneous 2-D temperature distributions in two cross-sections can disclose the combustion status inside the furnace. The measured radiative properties of particles in the furnace proved there is significant scattering in coal-fired boiler furnaces and it can provide useful information for the calculation of radiative heat transfer and numerical simulation of combustion in coal-fired boiler furnaces. The preliminary experimental results show this technology will be helpful for the combustion diagnosis in coal-fired boiler furnaces. (author)

Li, Wenhao; Lou, Chun; Sun, Yipeng; Zhou, Huaichun [State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, Wuhan, 430074 Hubei (China)



Application of Mixed Spin iMQCs for Temperature and Chemical-Selective Imaging  

PubMed Central

The development of accurate and non-invasive temperature imaging techniques has a wide variety of applications in fields such as medicine, chemistry and materials science. Accurate detection of temperature both in phantoms and in vivo can be obtained using iMQCs (intermolecular multiple quantum coherences), as demonstrated in a recent paper [1]. This paper describes the underlying theory of iMQC temperature detection, as well as extensions of that work allowing not only for imaging of absolute temperature but also for imaging of analyte concentrations through chemically selective spin density imaging.

Jenista, Elizabeth R.; Galiana, Gigi; Branca, Rosa T.; Yarmolenko, Pavel S.; Stokes, Ashley M.; Dewhirst, Mark W.; Warren, Warren S.



Accuracy of Lake and Stream Temperatures Estimated From Thermal Infrared Images  

NASA Astrophysics Data System (ADS)

Emitted thermal infrared radiation (TIR, lambda = 8 to 14 ?m) can be used to measure surface water temperatures (top approximately 100 ?m). This study evaluates the accuracy of stream (50 to 500 m wide) and lake (300 to 5,000 m wide) radiant temperatures (15 to 22°C) derived from airborne (MASTER, 5 to 15 m) and satellite (ASTER 90 m, Landsat ETM+ 60 m) TIR images. Applied atmospheric compensations changed water temperatures by -0.2 to +2.0°C. Atmospheric compensation depended primarily on atmospheric water vapor and temperature, sensor viewing geometry, and water temperature. Agreement between multiple TIR bands (MASTER -- 10 bands, ASTER -- 5 bands) provided an independent check on recovered temperatures. Compensations improved agreement between image and in situ surface temperatures (from 2.0 to 1.1°C average deviation); however, compensations did not improve agreement between river image temperatures and loggers installed at the stream bed (from 0.6 to 1.6°C average deviation). Analysis of field temperatures suggests that vertical thermal stratification may have caused a systematic difference between instream gage temperatures and corrected image temperatures. As a result, agreement between image temperatures and instream temperatures did not imply that accurate TIR temperatures were recovered. Based on these analyses, practical accuracies for corrected TIR lake and stream surface temperatures are around 1°C.

Kay, Jennifer E.; Kampf, Stephanie K.; Handcock, Rebecca N.; Cherkauer, Keith A.; Gillespie, Alan R.; Burges, Stephen J.



Effect of ageing treatments at high temperatures on the microstructure and mechanical behaviour of 2D nicalon\\/C\\/SiC composites. 2: Ageing under CO and influence of a SiC seal-coating  

Microsoft Academic Search

2D-Nicalon\\/C\\/SiC composites fabricated by CVI, either uncoated or protected with a SiC CVD sealcoating, have been aged at 1100–1300 °C under vacuum or carbon monoxide. They experienced a weight loss due to the decomposition of the SiO2xC1 ? x phase present in the fibers and to secondary reactions between carbon (from the fibers and the interphase) and the fiber decomposition

C. Labrugère; L. Guillaumat; A. Guette; R. Naslain



Temperature imaging of water in a microchannel using thermal sensitivity of near-infrared absorption.  


This paper presents a remote and preparation-free method of temperature imaging of aqueous solutions in microchannels of microfluidic chips. The principle of this method is based on the temperature dependency of the near-infrared (NIR) absorption band (?(2) + ?(3) band) of water. Temperature images were constructed from absorbances in a narrow wavelength range including 1908 nm, the most sensitive to temperature in the band, measured by using an NIR camera and an optical narrow-bandpass filter. Calculation and calibration results demonstrated a linear relationship between the absorption coefficient and temperature with a temperature coefficient of 1.5 × 10(-2) K(-1) mm(-1). Temperature images of 50 ?m thick water in a Y-shaped PDMS microchannel locally heated by a neighboring hot wire were obtained, in which thermal diffusion processes in the microchip were visualized. Temperature resolution was estimated to be approximately 0.2 K according to the temperature coefficient and noise level. PMID:21869986

Kakuta, Naoto; Fukuhara, Yuko; Kondo, Katsuya; Arimoto, Hidenobu; Yamada, Yukio



Synthesizing 2D directional moving texture  

Microsoft Academic Search

We present a novel patch-based algorithm for synthesizing a moving 2D texture, i.e. a sequence of frame-coherent 2D textures. In our method, the input are a sample texture and a 2D flow field. We first synthesize a 2D directional texture according to the direction information of the flow field and then let the texture move following the flow. Iteratively, the

Bin Wang; Wenping Wang; Junhai Yong; Jiaguang Sun



Linearization of electrostatically actuated surface micromachined 2-D optical scanner  

Microsoft Academic Search

This paper presents an effective method of linearizing the electrostatic transfer characteristics of micromachined two-dimensional (2-D) scanners. The orthogonal scan angles of surface micromachined polysilicon scanner are controlled by using quadrant electrodes for electrostatic actuation. By using a pair of differential voltages over a bias voltage, we could improve the distortion of projected images from 72% to only 13%. A

Hiroshi Toshiyoshi; Wibool Piyawattanametha; Cheng-Ta Chan; Ming C. Wu



E-2D advanced hawkeye: primary flight display  

Microsoft Academic Search

This paper is a response to the challenge of providing a large area avionics display for the E-2D AHE aircraft. The resulting display design provides a pilot with high-resolution visual information content covering an image area of almost three square feet (Active Area of Samsung display = 33.792cm x 27.0336 cm = 13.304\\

Paul W. Paolillo; Ragini Saxena; Jonathan Garruba; Sanjay Tripathi; Randy Blanchard



SQUID Microscopy: Magnetic Images of Room Temperature Samples  

NASA Astrophysics Data System (ADS)

We use a microscope based on a high-Tc Superconducting Quantum Interference Device (SQUID) to study room temperature samples. The SQUID, which measures magnetic flux, is mounted on a sapphire rod and maintained at 77 K inside a vacuum chamber. A sample, separated from the vacuum chamber by a window, is placed above the SQUID, and the entire microscope is enclosed within a magnetic shield. The sample can be scanned over the SQUID to obtain a magnetic image. We have used the microscope to study magnetotactic bacteria, which have a permanent magnetic dipole moment of about 1.5 x 10-16 Am^2. The bacteria, suspended in an aqueous medium, are placed in a cell which is separated from the vacuum chamber by a 3 micron thick SiN membrane. The sample is brought as close as 15 micron to the SQUID, and the magnetic flux noise from the motion of the bacteria is measured. Data from non-motile cells, which undergo Brownian motion, give us information about the distribution of lengths of the bacteria. By applying a magnetic field, we can determine the average dipole moment. Noise measurements of the live bacteria give us the rates of flagellar rotation and body-roll, as well as the amplitudes of the vibrational and precessional motions. Another application of the microscope is non-destruct