WorldWideScience

Sample records for nmr spiral imaging

  1. Featured Image: The Birth of Spiral Arms

    Science.gov (United States)

    Kohler, Susanna

    2017-01-01

    In this figure, the top panels show three spiral galaxies in the Virgo cluster, imaged with the Sloan Digital Sky Survey. The bottom panels provide a comparison with three morphologically similar galaxies generated insimulations. The simulations run by Marcin Semczuk, Ewa okas, and Andrs del Pino (Nicolaus Copernicus Astronomical Center, Poland) were designed to examine how the spiral arms of galaxies like the Milky Way may have formed. In particular, the group exploredthe possibility that so-called grand-design spiral arms are caused by tidal effects as a Milky-Way-like galaxy orbits a cluster of galaxies. The authors show that the gravitational potential of the cluster can trigger the formation of two spiral arms each time the galaxy passes through the pericenter of its orbit around the cluster. Check out the original paper below for more information!CitationMarcin Semczuk et al 2017 ApJ 834 7. doi:10.3847/1538-4357/834/1/7

  2. Spiral holographic imaging through quantum interference

    Science.gov (United States)

    Tang, Jie; Ming, Yang; Hu, Wei; Lu, Yan-qing

    2017-07-01

    Spiral holographic imaging in the Hong-Ou-Mandel interference scheme is introduced. Using spontaneous parametric down-conversion as a source of photon pairs, we analyze the joint orbital angular momentum spectrum of a reference photon and the photon encoding information of the object. The first-order interference of light beams in standard holographic imaging is replaced by the quantum interference of two-photon probability amplitudes. The difficulty in retrieving the amplitude and phase structure of an unknown photon is thereby avoided as classical interferometric techniques such as optical holography do not apply. Our results show that the full information of the object's transmission function can be recorded in the spiral hologram, which originates directly from the joint orbital angular momentum spectrum. This presents a lateral demonstration of compressive imaging and can potentially be used for remote sensing.

  3. Spiral phase contrast imaging in microscopy.

    Science.gov (United States)

    Fürhapter, Severin; Jesacher, Alexander; Bernet, Stefan; Ritsch-Marte, Monika

    2005-02-07

    We demonstrate an optical method for edge contrast enhancement in light microscopy. The method is based on holographic Fourier plane filtering of the microscopic image with a spiral phase element (also called vortex phase or helical phase filter) displayed as an off-axis hologram at a computer controlled high resolution spatial light modulator (SLM) in the optical imaging pathway. The phase hologram imprints a helical phase term of the form exp(i phi) on the diffracted light field in its Fourier plane. In the image plane, this results in a strong and isotropic edge contrast enhancement for both amplitude and phase objects.

  4. Development in NMR spiral imaging and application to the assessment of the permeability of the blood-brain barrier on 2 models of brain tumors; Developpements en imagerie RMN spirale et application a la caracterisation de la permeabilite de la barriere hemato-encephalique sur deux modeles de tumeurs intracerebrales

    Energy Technology Data Exchange (ETDEWEB)

    Beaumont, M

    2007-12-15

    The results presented in this work were obtained as part of methodological developments in magnetic resonance imaging. First of all, the setting of the rapid imaging technique using a k-space sampling scheme along a variable density spiral is described. Numerical simulations were used to optimize the acquisitions parameters and to compare different reconstruction techniques. An original approach to calibrate the k-space trajectory was proposed. Then, spiral imaging was used to implement a method to measure the blood brain barrier permeability to Gd-DOTA. This protocol was combined to blood volume and vessel size index measurements using Sinerem. The results obtained highlighted differences between the microvascular parameters measured on C6 and RG2 tumor models. The presence of Sinerem induces a mean decrease of the transfer constant across the vascular wall (Ktrans), in the tumor, of 24 per cent. This study also showed extravasation of the Sinerem, during the first two hours after the product injection, only in the RG2 tumors. (author)

  5. Medical applications of NMR imaging and NMR spectroscopy with stable isotopes. Summary

    Energy Technology Data Exchange (ETDEWEB)

    Matwiyoff, N.A.

    1983-01-01

    The current status of NMR imaging and NMR spectroscopy are summarized. For the most part examples from the March 1983 Puerto Rico symposium are used to illustrate the utility of NMR in medicine. 18 refs., 5 figs.

  6. Early non-destructive biofouling detection in spiral wound RO Membranes using a mobile earth's field NMR

    KAUST Repository

    Fridjonsson, E.O.

    2015-04-20

    We demonstrate the use of Earth\\'s field (EF) Nuclear Magnetic Resonance (NMR) to provide early non-destructive detection of active biofouling of a commercial spiral wound reverse osmosis (RO) membrane module. The RO membrane module was actively biofouled to different extents, by the addition of biodegradable nutrients to the feed stream, as revealed by a subtle feed-channel pressure drop increase. Easily accessible EF NMR parameters (signal relaxation parameters T1, T2 and the total NMR signal modified to be sensitive to stagnant fluid only) were measured and analysed in terms of their ability to detect the onset of biofouling. The EF NMR showed that fouling near the membrane module entrance significantly distorted the flow field through the whole membrane module. The total NMR signal is shown to be suitable for non-destructive early biofouling detection of spiral wound membrane modules, it was readily deployed at high (operational) flow rates, was particularly sensitive to flow field changes due to biofouling and could be deployed at any position along the membrane module axis. In addition to providing early fouling detection, the mobile EF NMR apparatus could also be used to (i) evaluate the production process of spiral wound membrane modules, and (ii) provide an in-situ determination of module cleaning process efficiency.

  7. Quantitative imaging of complex samples by spiral phase contrast microscopy.

    Science.gov (United States)

    Bernet, Stefan; Jesacher, Alexander; Fürhapter, Severin; Maurer, Christian; Ritsch-Marte, Monika

    2006-05-01

    Recently a spatial spiral phase filter in a Fourier plane of a microscopic imaging setup has been demonstrated to produce edge enhancement and relief-like shadow formation of amplitude and phase samples. Here we demonstrate that a sequence of at least 3 spatially filtered images, which are recorded with different rotational orientations of the spiral phase plate, can be used to obtain a quantitative reconstruction of both, amplitude and phase information of a complex microscopic sample, i.e. an object consisting of mixed absorptive and refractive components. The method is demonstrated using a calibrated phase sample, and an epithelial cheek cell.

  8. Digital spiral-slit for bi-photon imaging

    Science.gov (United States)

    McLaren, Melanie; Forbes, Andrew

    2017-04-01

    Quantum ghost imaging using entangled photon pairs has become a popular field of investigation, highlighting the quantum correlation between the photon pairs. We introduce a technique using spatial light modulators encoded with digital holograms to recover both the amplitude and the phase of the digital object. Down-converted photon pairs are entangled in the orbital angular momentum basis, and are commonly measured using spiral phase holograms. Consequently, by encoding a spiral ring-slit hologram into the idler arm, and varying it radially we can simultaneously recover the phase and amplitude of the object in question. We demonstrate that a good correlation between the encoded field function and the reconstructed images exists.

  9. BOOK REVIEW: NMR Imaging of Materials

    Science.gov (United States)

    Blümich, Bernhard

    2003-09-01

    Magnetic resonance imaging (MRI) of materials is a field of increasing importance. Applications extend from fundamental science like the characterization of fluid transport in porous rock, catalyst pellets and hemodialysers into various fields of engineering for process optimization and product quality control. While the results of MRI imaging are being appreciated by a growing community, the methods of imaging are far more diverse for materials applications than for medical imaging of human beings. Blümich has delivered the first book in this field. It was published in hardback three years ago and is now offered as a paperback for nearly half the price. The text provides an introduction to MRI imaging of materials covering solid-state NMR spectroscopy, imaging methods for liquid and solid samples, and unusual MRI in terms of specialized approaches to spatial resolution such as an MRI surface scanner. The book represents an excellent and thorough treatment which will help to grow research in materials MRI. Blümich developed the treatise over many years for his research students, graduates in chemistry, physics and engineering. But it may also be useful for medical students looking for a less formal discussion of solid-state NMR spectroscopy. The structure of this book is easy to perceive. The first three chapters cover an introduction, the fundamentals and methods of solid-state NMR spectroscopy. The book starts at the ground level where no previous knowledge about NMR is assumed. Chapter 4 discusses a wide variety of transformations beyond the Fourier transformation. In particular, the Hadamard transformation and the 'wavelet' transformation are missing from most related books. This chapter also includes a description of noise-correlation spectroscopy, which promises the imaging of large objects without the need for extremely powerful radio-frequency transmitters. Chapters 5 and 6 cover basic imaging methods. The following chapter about the use of relaxation and

  10. Optical image encryption in Fresnel domain using spiral phase transform

    Science.gov (United States)

    Kumar, Ravi; Bhaduri, Basanta

    2017-09-01

    In this study, we propose a new nonlinear optical image encryption technique using spiral phase transform (SPT). First, the primary image is phase encoded and multiplied with a random amplitude mask (RAM), and using power function, the product is then powered to m. This powered output is Fresnel propagated with distance z 1 and then modulated with a random phase mask (RPM). The modulated image is further Fresnel propagated with distance z 2. Similarly, a security image is also modulated with another RAM and then Fresnel propagated with distance z 3. Next, the two modulated images after Fresnel propagations, are interfered and further Fresnel propagated with distance z 4 to get a complex image. Finally, this complex image is SPT with particular spiral phase function (SPF), to get the final encrypted image for transmission. In the proposed technique, the security keys are Fresnel propagation distances, the security image, RPM, RAMs, power order, m, and order of SPF, q. Numerical simulation results confirm the validity and effectiveness of the proposed technique. The proposed technique is robust against noise and brutal force attacks.

  11. 3D Reconstruction of NMR Images

    Directory of Open Access Journals (Sweden)

    Peter Izak

    2007-01-01

    Full Text Available This paper introduces experiment of 3D reconstruction NMR images scanned from magnetic resonance device. There are described methods which can be used for 3D reconstruction magnetic resonance images in biomedical application. The main idea is based on marching cubes algorithm. For this task was chosen sophistication method by program Vision Assistant, which is a part of program LabVIEW.

  12. Abdominal wall hernias: imaging with spiral CT

    Energy Technology Data Exchange (ETDEWEB)

    Stabile Ianora, A.A.; Midiri, M.; Vinci, R.; Rotondo, A.; Angelelli, G. [Department of Radiology, Bari University Hospital (Italy)

    2000-06-01

    Computed tomography is an accurate method of identifying the various types of abdominal wall hernias, especially if they are clinically occult, and of distinguishing them from other diseases such as hematomas, abscesses and neoplasia. In this study we examined the CT images of 94 patients affected by abdominal wall hernias observed over a period of 6 years. Computed tomography clearly demonstrates the anatomical site of the hernial sac, the content and any occlusive bowel complications due to incarceration or strangulation. Clinical diagnosis of external hernias is particularly difficult in obese patients or in those with laparotic scars. In these cases abdominal imaging is essential for a correct preoperative diagnosis and to determine the most effective treatment. (orig.)

  13. Fourier Analysis and Structure Determination. Part II: Pulse NMR and NMR Imaging.

    Science.gov (United States)

    Chesick, John P.

    1989-01-01

    Uses simple pulse NMR experiments to discuss Fourier transforms. Studies the generation of spin echoes used in the imaging procedure. Shows that pulse NMR experiments give signals that are additions of sinusoids of differing amplitudes, frequencies, and phases. (MVL)

  14. A Spiral And Discipline-Oriented Curriculum In Medical Imaging

    DEFF Research Database (Denmark)

    Wilhjelm, Jens E.; Hanson, Lars G.; Henneberg, Kaj-Åge

    2011-01-01

    This contribution describes and evaluates an experimental combination of a spiral and discipline-oriented curriculum implemented in the bachelor’s and master’s program in Medicine and Technology. The implementation in the master’s program is in the form of a study line in Medical Imaging and Radi......This contribution describes and evaluates an experimental combination of a spiral and discipline-oriented curriculum implemented in the bachelor’s and master’s program in Medicine and Technology. The implementation in the master’s program is in the form of a study line in Medical Imaging......, but in a gradually more advanced manner. The remaining courses in the master’s program follow a discipline-oriented curriculum. From a practical point of view, the spiral course portfolio works well in an undergraduate environment, where the courses involved are to be taken by all students and in the order planned...... on their intuitive understanding of the subject. The program was evaluated in terms of the progression in scientific demands in exam from course to course and in terms of the pattern of course selection by the students. The analysis was based on 96 students. The pattern of course selection was found to follow...

  15. Dynamic NMR cardiac imaging in a piglet

    Energy Technology Data Exchange (ETDEWEB)

    Doyle, M.; Rzedzian, R.; Mansfield, P. (Nottingham Univ. (UK). Dept. of Physics); Coupland, R.E. (Nottingham Univ. (UK). Queen' s Medical Centre)

    1983-12-01

    NMR echo-planar imaging (EPI) has been used in a real-time mode to visualise the thorax of a live piglet. Moving pictures are available on an immediate image display system which demonstrates dynamic cardiac function. Frame rates vary from one per cardiac cycle in a prospective stroboscopic mode with immediate visual output to a maximum of 10 frames per second yielding up to six looks in one piglet heart cycle, but using a visual playback mode. A completely new system has been used to obtain these images, features of which include a probe assembly with 22 cm access and an AP400 array processor for real-time data processing.

  16. Information preserving image compression for archiving NMR images.

    Science.gov (United States)

    Li, C C; Gokmen, M; Hirschman, A D; Wang, Y

    1991-01-01

    This paper presents a result on information preserving compression of NMR images for the archiving purpose. Both Lynch-Davisson coding and linear predictive coding have been studied. For NMR images of 256 x 256 x 12 resolution, the Lynch-Davisson coding with a block size of 64 as applied to prediction error sequences in the Gray code bit planes of each image gave an average compression ratio of 2.3:1 for 14 testing images. The predictive coding with a third order linear predictor and the Huffman encoding of the prediction error gave an average compression ratio of 3.1:1 for 54 images under test, while the maximum compression ratio achieved was 3.8:1. This result is one step further toward the improvement, albeit small, of the information preserving image compression for medical applications.

  17. Spiral computed tomographic imaging related to computerized ultrasonographic images of carotid plaque morphology and histology

    DEFF Research Database (Denmark)

    Grønholdt, Marie-Louise; Wagner, A; Wiebe, B M;

    2001-01-01

    Echolucency of carotid atherosclerotic plaques, as evaluated by computerized B-mode ultrasonographic images, has been associated with an increased incidence of brain infarcts on cerebral computed tomographic scans. We tested the hypotheses that characterization of carotid plaques on spiral comput...

  18. Spiral computed tomographic imaging related to computerized ultrasonographic images of carotid plaque morphology and histology

    DEFF Research Database (Denmark)

    Grønholdt, Marie-Louise; Wagner, A; Wiebe, B M

    2001-01-01

    Echolucency of carotid atherosclerotic plaques, as evaluated by computerized B-mode ultrasonographic images, has been associated with an increased incidence of brain infarcts on cerebral computed tomographic scans. We tested the hypotheses that characterization of carotid plaques on spiral comput...

  19. Instrumentation in NMR/NMR imaging; Instrumentation en RMN/IRM

    Energy Technology Data Exchange (ETDEWEB)

    Favre, B.; Desgoutte, P.; Marguet, Ch. [Universite Claude Bernard, Lab. de Resonance Magnetique Nuleaire, 69 - Villeurbanne (France)

    1999-07-01

    Nuclear Magnetic Resonance (NMR) is largely used in medical imaging and in spectroscopy for the chemistry. The equipment is complex and explosive, and is not easily accessible for teaching. The didactic machine presented here allows, thanks to an extreme simplification, to approach essential notions of NMR with a cost and a space-factor reduced. It allows to visualize the phenomenon of NMR, to illustrate its main applications, and to measure main parameters concerning the magnetic field or the sample. In addition, it can be used to study signal acquisition and processing, fundamental digital and analog electronic circuits, programming... (authors)

  20. Image edge-enhancement in optical microscopy with a phase mismatched spiral phase plate

    Institute of Scientific and Technical Information of China (English)

    Shibiao Wei; Jing Bu; Siwei Zhu; Xiaocong Yuan

    2011-01-01

    @@ We present a spiral phase filtering system with a large tolerance for edge enhancement of both phase and amplitude objects in optical microscopy.The method is based on a Fourier 4-f spatial filtering system.A phase mismatched spiral phase plate (SPP) fabricated by electron beam lithography is employed as the radial Hilbert transform for image edge enhancement.Compared with holography, SPP is simple,economical, reliable, and easy to integrate.%We present a spiral phase filtering system with a large tolerance for edge enhancement of both phase and amplitude objects in optical microscopy. The method is based on a Fourier 4-f spatial filtering system.A phase mismatched spiral phase plate (SPP) fabricated by electron beam lithography is employed as the radial Hilbert transform for image edge enhancement. Compared with holography, SPP is simple,economical, reliable, and easy to integrate.

  1. NMR imaging and cryoporometry of swelling clays

    Science.gov (United States)

    Dvinskikh, Sergey V.; Szutkowski, Kosma; Petrov, Oleg V.; Furó, István.

    2010-05-01

    Compacted bentonite clay is currently attracting attention as a promising "self-sealing" buffer material to build in-ground barriers for the encapsulation of radioactive waste. It is expected to fill up the space between waste canister and surrounding ground by swelling and thus delay flow and migration from the host rock to the canister. In environmental sciences, evaluation and understanding of the swelling properties of pre-compacted clay are of uttermost importance for designing such buffers. Major goal of present study was to provide, in a non-invasive manner, a quantitative measure of bentonite distribution in extended samples during different physical processes in an aqueous environment such as swelling, dissolution, and sedimentation on the time scale from minutes to years. The propagation of the swelling front during clay expansion depending on the geometry of the confining space was also studied. Magnetic resonance imaging and nuclear magnetic resonance spectroscopy were adapted and used as main experimental techniques. With this approach, spatially resolved movement of the clay/water interface as well as clay particle distributions in gel phase can be monitored [1]. Bulk samples with swelling in a vertical tube and in a horizontal channel were investigated and clay content distribution profiles in the concentration range over five orders of magnitude and with sub-millimetre spatial resolution were obtained. Expansion rates for bulk swelling and swelling in narrow slits were compared. For sodium-exchanged montmorillonite in contact with de-ionised water, we observed a remarkable acceleration of expansion as compared to that obtained in the bulk. To characterize the porosity of the clay a cryoporometric study [2] has been performed. Our results have important implications to waste repository designs and for the assessment of its long-term performance. Further research exploring clay-water interaction over a wide variety of clay composition and water ionic

  2. NMR and Mushrooms : imaging post harvest senescence

    NARCIS (Netherlands)

    Donker, H.C.W.

    1999-01-01

    The objective of the study described in this thesis was to explore the potentials of NMR for the study of water relations in harvested mushrooms ( Agaricus bisporus ). Since harvested mushrooms tend to continue their growth after harvest, their morphogenesis is heavily influenced by the external cli

  3. Image edge enhancement for moving objects with a spiral phase filter

    Science.gov (United States)

    Shan, Mingguang; Bao, Shanshan; Zhong, Zhi; Hao, Bengong; An, Chengquan

    2013-10-01

    A fast image edge enhancement method for moving objects is presented with a spiral phase filter using radial Hilbert transform theory. The spiral phase filter is placed in the Fourier plane of a 4f optical system, and used to process the spectral of objects image to achieve 2-D image edge enhancement of shape-free objects. All the directions of object edge can be enhanced similarly because there is a phase difference π along any diameter direction of the spiral phase filter. The results show that this method has good performance for enhancing the edge of moving objects. The advantages of this method are simple operations, clear edge images, high measurement speed and automatic measurement.

  4. 3D Reconstruction of NMR Images by LabVIEW

    Directory of Open Access Journals (Sweden)

    Peter IZAK

    2007-01-01

    Full Text Available This paper introduces the experiment of 3D reconstruction NMR images via virtual instrumentation - LabVIEW. The main idea is based on marching cubes algorithm and image processing implemented by module of Vision assistant. The two dimensional images shot by the magnetic resonance device provide information about the surface properties of human body. There is implemented algorithm which can be used for 3D reconstruction of magnetic resonance images in biomedical application.

  5. NMR-Based Diffusion Lattice Imaging

    CERN Document Server

    Laun, Frederik Bernd

    2013-01-01

    Nuclear magnetic resonance (NMR) diffusion experiments are widely employed as they yield information about structures hindering the diffusion process, e.g. about cell membranes. While it has been shown in recent articles, that these experiments can be used to determine the exact shape of closed pores averaged over a volume of interest, it is still an open question how much information can be gained in open systems. In this theoretical work, we show that the full structure information of periodic open systems is accessible. To this end, the so-called 'SEquential Rephasing by Pulsed field-gradient Encoding N Time-intervals' (SERPENT) sequence is used, which employs several diffusion weighting gradient pulses with different amplitudes. The structural information is obtained by an iterative technique relying on a Gaussian envelope model of the diffusion propagator. Two solid matrices that are surrounded by an NMR-visible medium are considered: a hexagonal lattice of cylinders and a cubic lattice of triangles.

  6. Log-Spiral Keypoint: A Robust Approach toward Image Patch Matching

    Directory of Open Access Journals (Sweden)

    Kangho Paek

    2015-01-01

    Full Text Available Matching of keypoints across image patches forms the basis of computer vision applications, such as object detection, recognition, and tracking in real-world images. Most of keypoint methods are mainly used to match the high-resolution images, which always utilize an image pyramid for multiscale keypoint detection. In this paper, we propose a novel keypoint method to improve the matching performance of image patches with the low-resolution and small size. The location, scale, and orientation of keypoints are directly estimated from an original image patch using a Log-Spiral sampling pattern for keypoint detection without consideration of image pyramid. A Log-Spiral sampling pattern for keypoint description and two bit-generated functions are designed for generating a binary descriptor. Extensive experiments show that the proposed method is more effective and robust than existing binary-based methods for image patch matching.

  7. NMR imaging of fluid dynamics in reservoir core.

    Science.gov (United States)

    Baldwin, B A; Yamanashi, W S

    1988-01-01

    A medical NMR imaging instrument has been modified to image water and oil in reservoir rocks by the construction of a new receiving coil. Both oil and water inside the core produced readily detectable proton NMR signals, while the rock matrix produced no signal. Because of similar T2 NMR relaxation times, the water was doped with a paramagnetic ion, Mn+2, to reduce its T2 relaxation time. This procedure enhanced the separation between the oil and water phases in the resulting images. Sequential measurements, as water imbibed into one end and oil was expelled from the other end of a core plug, produced a series of images which showed the dynamics of the fluids. For water-wet Berea Sandstone a flood front was readily observed, but some of the oil was apparently left behind in small, isolated pockets which were larger than individual pores. After several additional pore volumes of water flowed through the plug the NMR image indicated a homogeneous distribution of oil. The amount of residual oil, as determined from the ratio of NMR intensities, closely approximated the residual oil saturation of fully flooded Berea samples measured by Dean-Stark extraction. A Berea sandstone core treated to make it partially oil-wet, did not show a definitive flood front, but appeared to channel the water around the perimeter of the core plug. The relative ease with which these images were made indicates that NMR imaging can be a useful technique to follow the dynamics of oil and water through a core plug for a variety of production processes.

  8. Spiral Arms in Gravitationally Unstable Protoplanetary Disks as Imaged in Scattered Light

    CERN Document Server

    Dong, Ruobing; Rice, Ken; Chiang, Eugene

    2015-01-01

    Combining 3D smoothed-particle hydrodynamics and Monte Carlo radiative transfer calculations, we examine the morphology of spiral density waves induced by gravitational instability (GI) in protoplanetary disks, as they would appear in direct images at near-infrared (NIR) wavelengths. We find that systems with disk-to-star-mass ratios q=M_disk/M_star that are ~0.25 or more may produce prominent spiral arms in NIR imaging, remarkably resembling features observed in the MWC 758 and SAO 206462 systems. The contrast of GI-induced arms at NIR wavelengths can reach a factor of ~3, and their pitch angles are about 10-15 degree. The dominant azimuthal wavenumber of GI-induced spiral arms roughly obeys m~1/q in the range 2~0.25; and that the accretion rate Mdot be high, on the order of 1e-6 solar mass per year.

  9. Faster imaging with a portable unilateral NMR device.

    Science.gov (United States)

    Liberman, Asaf; Bergman, Elad; Sarda, Yifat; Nevo, Uri

    2013-06-01

    Unilateral NMR devices are important tools in various applications such as non-destructive testing and well logging, but are not applied routinely for imaging, primarily because B0 inhomogeneity in these scanners leads to a relatively low signal and requires use of the slow single point imaging scan scheme. Enabling high quality, fast imaging could make this affordable and portable technology practical for various imaging applications as well as for new applications that are not yet feasible with MRI technology. The goal of this work was to improve imaging times in a portable unilateral NMR scanner. Both Compressed Sensing and Fast Spin Echo were modified and applied to fit the unique characteristics of a unilateral device. Two printed phantoms, allowing high resolution images, were scanned with both methods and compared to a standard scan and to a low pass scan to evaluate performance. Both methods were found to be feasible with a unilateral device, proving ways to accelerate single point imaging in such scanners. This outcome encourages us to explore how to further accelerate imaging times in unilateral NMR devices so that this technology might become clinically applicable in the future.

  10. Digital image communication scheme based on the breakup of spiral waves

    Science.gov (United States)

    Vaidelys, Martynas; Lu, Chen; Cheng, Yujie; Ragulskis, Minvydas

    2017-02-01

    A digital image communication scheme based on the breakup of spiral waves is presented in this paper. This communication system does not require spatially homogeneous random initial conditions. Moreover, the secret image is not embedded into the initial conditions of the evolving self-organizing patterns. Such features increase the security of the communication, but still enable an effective transmission of the secret image. Computational experiments are used to demonstrate the properties and efficiency of the proposed scheme.

  11. NMR clinical imaging and spectroscopy: Its impact on nuclear medicine

    Energy Technology Data Exchange (ETDEWEB)

    1990-02-02

    This is a collection of four papers describing aspects of past and future use of nuclear magnetic resonance as a clinical diagnostic tool. The four papers are entitled (1) What Does NMR Offer that Nuclear Medicine Does Not by Jerry W. Froelich, (2) Oncological Imaging: Now, Future and Impact Jerry W. Froelich, (3) Magnetic Resonance Spectroscopy/Spectroscopic Imaging and Nuclear Medicine: Past, Present and Future by H. Cecil Charles, and (4) MR Cardiology: Now, Future and Impact by Robert J. Herfkens.

  12. NMR clinical imaging and spectroscopy: Its impact on nuclear medicine

    Energy Technology Data Exchange (ETDEWEB)

    1990-02-02

    This is a collection of four papers describing aspects of past and future use of nuclear magnetic resonance as a clinical diagnostic tool. The four papers are entitled (1) What Does NMR Offer that Nuclear Medicine Does Not? by Jerry W. Froelich, (2) Oncological Imaging: Now, Future and Impact Jerry W. Froelich, (3) Magnetic Resonance Spectroscopy/Spectroscopic Imaging and Nuclear Medicine: Past, Present and Future by H. Cecil Charles, and (4) MR Cardiology: Now, Future and Impact by Robert J. Herfkens.

  13. Improved first-pass spiral myocardial perfusion imaging with variable density trajectories.

    Science.gov (United States)

    Salerno, Michael; Sica, Christopher; Kramer, Christopher M; Meyer, Craig H

    2013-11-01

    To develop and evaluate variable-density spiral first-pass perfusion pulse sequences for improved efficiency and off-resonance performance and to demonstrate the utility of an apodizing density compensation function (DCF) to improve signal-to-noise ratio (SNR) and reduce dark-rim artifact caused by cardiac motion and Gibbs Ringing. Three variable density spiral trajectories were designed, simulated, and evaluated in 18 normal subjects, and in eight patients with cardiac pathology on a 1.5T scanner. By using a DCF, which intentionally apodizes the k-space data, the sidelobe amplitude of the theoretical point spread function (PSF) is reduced by 68%, with only a 13% increase in the full-width at half-maximum of the main-lobe when compared with the same data corrected with a conventional variable-density DCF, and has an 8% higher resolution than a uniform density spiral with the same number of interleaves and readout duration. Furthermore, this strategy results in a greater than 60% increase in measured SNR when compared with the same variable-density spiral data corrected with a conventional DCF (P density spiral pulse sequences using an apodized DCF produce high-quality first-pass perfusion images with minimal dark-rim and off-resonance artifacts, high SNR and contrast-to-noise ratio, and good delineation of resting perfusion abnormalities. Copyright © 2012 Wiley Periodicals, Inc.

  14. NMR imaging of cell phone radiation absorption in brain tissue.

    Science.gov (United States)

    Gultekin, David H; Moeller, Lothar

    2013-01-02

    A method is described for measuring absorbed electromagnetic energy radiated from cell phone antennae into ex vivo brain tissue. NMR images the 3D thermal dynamics inside ex vivo bovine brain tissue and equivalent gel under exposure to power and irradiation time-varying radio frequency (RF) fields. The absorbed RF energy in brain tissue converts into Joule heat and affects the nuclear magnetic shielding and the Larmor precession. The resultant temperature increase is measured by the resonance frequency shift of hydrogen protons in brain tissue. This proposed application of NMR thermometry offers sufficient spatial and temporal resolution to characterize the hot spots from absorbed cell phone radiation in aqueous media and biological tissues. Specific absorption rate measurements averaged over 1 mg and 10 s in the brain tissue cover the total absorption volume. Reference measurements with fiber optic temperature sensors confirm the accuracy of the NMR thermometry.

  15. Time-of-flight flow imaging using NMR remote detection

    Energy Technology Data Exchange (ETDEWEB)

    Granwehr, Josef; Harel, Elad; Han, Song-I; Garcia, Sandra; Pines,Alex; Sen, Pabitra N.; Song, Yi-Qiao

    2005-05-05

    A time-of-flight imaging technique is introduced to visualize fluid flow and dispersion through porous media using NMR. As the fluid flows through a sample, the nuclear spin magnetization is modulated by RF pulses and magnetic field gradients to encode the spatial coordinates of the fluid. When the fluid leaves the sample, its magnetization is recorded by a second RF coil. This scheme not only facilitates a time-dependent imaging of fluid flow, it also allows a separate optimization of encoding and detection subsystems to enhance overall sensitivity. The technique is demonstrated by imaging gas flow through a porous rock.

  16. High-resolution NMR imaging of the hand

    Energy Technology Data Exchange (ETDEWEB)

    Koenig, H.; Lucas, D.

    1986-12-01

    With high spatial resolution guaranteed, NMR imaging allows to simultaneously make visible the complex osseous, chondral, and ligamentous structures of the hand. The examinations reported on were made with a 1.0 Tesla Magnetom using a special surface coil so as to achieve cut heights of 3-4 mm and an in-plane resolution of 0.5 mm. In addition to normal test persons, 29 patients were examined who had pseudoarthrosis of the os naviculare, lunatomalacia, rheumatic arthritis, or bone and soft-tissue tumors. Comparison with X-ray radiography or bone scintiscans showed that NMR imaging is capable of demonstrating localisation and extension of bone marrow or bone joint abnormalities at an earlier stage.

  17. 3D imaging with an isocentric mobile C-arm. Comparison of image quality with spiral CT

    Energy Technology Data Exchange (ETDEWEB)

    Kotsianos, Dorothea; Wirth, Stefan; Fischer, Tanja; Euler, Ekkehard; Rock, Clemens; Linsenmaier, Ulrich; Pfeifer, Klaus Juergen; Reiser, Maximilian [Departments of Radiology and Surgery, Klinikum der Universitaet Muenchen, Innenstadt, Nussbaumstrasse 20, 80336, Munchen (Germany)

    2004-09-01

    The purpose of this study was to evaluate the image quality of the new 3D imaging system (ISO-C-3D) for osteosyntheses of tibial condylar fractures in comparison with spiral CT (CT). Sixteen human cadaveric knees were examined with a C-arm 3D imaging system and spiral computed tomography. Various screws and plates of steel and titanium were used for osteosynthesis in these specimens. Image quality and clinical value of multiplanar (MP) reformatting of both methods were analyzed. In addition, five patients with tibial condylar fractures were examined for diagnosis and intra-operative control. The image quality of the C-arm 3D imaging system in the cadaveric study was rated as significantly worse than that of spiral CT with and without prostheses. After implantation of prostheses an increased incidence of artifacts was observed, but the diagnostic accuracy was not affected. Titanium implants caused the smallest number of artifacts. The image quality of ISO-C is inferior to CT, and metal artifacts were more prominent, but the clinical value was equal. ISO-C-3D can be useful in planning operative reconstructions and can verify the reconstruction of articular surfaces and the position of implants with diagnostic image quality. (orig.)

  18. 3D imaging with an isocentric mobile C-arm comparison of image quality with spiral CT.

    Science.gov (United States)

    Kotsianos, Dorothea; Wirth, Stefan; Fischer, Tanja; Euler, Ekkehard; Rock, Clemens; Linsenmaier, Ulrich; Pfeifer, Klaus Jürgen; Reiser, Maximilian

    2004-09-01

    The purpose of this study was to evaluate the image quality of the new 3D imaging system (ISO-C-3D) for osteosyntheses of tibial condylar fractures in comparison with spiral CT (CT). Sixteen human cadaveric knees were examined with a C-arm 3D imaging system and spiral computed tomography. Various screws and plates of steel and titanium were used for osteosynthesis in these specimens. Image quality and clinical value of multiplanar (MP) reformatting of both methods were analyzed. In addition, five patients with tibial condylar fractures were examined for diagnosis and intra-operative control. The image quality of the C-arm 3D imaging system in the cadaveric study was rated as significantly worse than that of spiral CT with and without prostheses. After implantation of prostheses an increased incidence of artifacts was observed, but the diagnostic accuracy was not affected. Titanium implants caused the smallest number of artifacts. The image quality of ISO-C is inferior to CT, and metal artifacts were more prominent, but the clinical value was equal. ISO-C-3D can be useful in planning operative reconstructions and can verify the reconstruction of articular surfaces and the position of implants with diagnostic image quality.

  19. NMR imaging of cell phone radiation absorption in brain tissue

    OpenAIRE

    Gultekin, David H.; Moeller, Lothar

    2012-01-01

    A method is described for measuring absorbed electromagnetic energy radiated from cell phone antennae into ex vivo brain tissue. NMR images the 3D thermal dynamics inside ex vivo bovine brain tissue and equivalent gel under exposure to power and irradiation time-varying radio frequency (RF) fields. The absorbed RF energy in brain tissue converts into Joule heat and affects the nuclear magnetic shielding and the Larmor precession. The resultant temperature increase is measured by the resonance...

  20. Human in vivo phosphate metabolite imaging with 31P NMR.

    Science.gov (United States)

    Bottomley, P A; Charles, H C; Roemer, P B; Flamig, D; Engeseth, H; Edelstein, W A; Mueller, O M

    1988-07-01

    Phosphorus (31P) spectroscopic images showing the distribution of high-energy phosphate metabolites in the human brain have been obtained at 1.5 T in scan times of 8.5 to 34 min at 27 and 64 cm3 spatial resolution using pulsed phase-encoding gradient magnetic fields and three-dimensional Fourier transform (3DFT) techniques. Data were acquired as free induction decays with a quadrature volume NMR detection coil of a truncated geometry designed to optimize the signal-to-noise ratio on the coil axis on the assumption that the sample noise represents the dominant noise source, and self-shielded magnetic field gradient coils to minimize eddy-current effects. The images permit comparison of metabolic data acquired simultaneously from different locations in the brain, as well as metabolite quantification by inclusion of a vial containing a standard of known 31P concentration in the image array. Values for the NMR visible adenosine triphosphate in three individuals were about 3 mM of tissue. The ratio of NMR detectable phosphocreatine to ATP in brain was 1.15 +/- 0.17 SD in these experiments. Potential sources of random and systematic error in these and other 31P measurements are identified.

  1. Exploiting image registration for automated resonance assignment in NMR.

    Science.gov (United States)

    Strickland, Madeleine; Stephens, Thomas; Liu, Jian; Tjandra, Nico

    2015-06-01

    Analysis of protein NMR data involves the assignment of resonance peaks in a number of multidimensional data sets. To establish resonance assignment a three-dimensional search is used to match a pair of common variables, such as chemical shifts of the same spin system, in different NMR spectra. We show that by displaying the variables to be compared in two-dimensional plots the process can be simplified. Moreover, by utilizing a fast Fourier transform cross-correlation algorithm, more common to the field of image registration or pattern matching, we can automate this process. Here, we use sequential NMR backbone assignment as an example to show that the combination of correlation plots and segmented pattern matching establishes fast backbone assignment in fifteen proteins of varying sizes. For example, the 265-residue RalBP1 protein was 95.4% correctly assigned in 10 s. The same concept can be applied to any multidimensional NMR data set where analysis comprises the comparison of two variables. This modular and robust approach offers high efficiency with excellent computational scalability and could be easily incorporated into existing assignment software.

  2. NMR imaging of the liver. Diagnostics, differential diagnostics, therapeutic approaches; MRT der Leber. Diagnostik, Differenzialdiagnostik, Therapieansaetze

    Energy Technology Data Exchange (ETDEWEB)

    Fischbach, Frank; Fischbach, Katharina [Universitaetsklinikum Magdeburg A.oe.R. (Germany). Klinik fuer Radiologie und Nuklearmedizin

    2017-03-01

    The book on NMR imaging of the liver covers the following issues: Fundamentals of NMR imaging, T1-weighted imaging; T2-weighted imaging, diffusion-weighted imaging, cavernous hemangioma, focal nodular hyperplasy; hepatocellular adenoma, hepatocellulas carcinoma, cholangiocellular carcinoma, hepatic metastases.

  3. [Diagnostic imaging in acute pulmonary embolism. The use of spiral computed tomography, lung scintigraphy and echocardiography].

    Science.gov (United States)

    Hess, Søren; Madsen, Poul Henning; Jørgensen, Henrik Boel; Høilund-Carlsen, Poul Flemming

    2005-10-10

    Acute pulmonary embolism is an underdiagnosed and potentially lethal condition. Treatment may be lifesaving but is associated with severe side effects. Thus, reliable diagnostic imaging is essential. We conducted a literature review on the use of spiral computed tomography, lung scintigraphy and echocardiography in acute pulmonary embolism and identified 562 articles, of which 16 original papers met our inclusion criteria. From these, we concluded that none of the modalities is applicable in every situation. Spiral computed tomography can confirm the diagnosis but cannot rule out subsegmental embolism. With lung scintigraphy, perfusion imaging alone is probably sufficient and suited to both confirming and ruling out the diagnosis. Echocardiography should be reserved for patients with an emergent need for treatment and cannot rule out the diagnosis.

  4. Non-Cartesian Parallel Imaging Reconstruction of Undersampled IDEAL Spiral 13C CSI Data

    DEFF Research Database (Denmark)

    Hansen, Rie Beck; Hanson, Lars G.; Ardenkjær-Larsen, Jan Henrik

    The short-lived nature of hyperpolarization places high demands on signal acquisition. To acquire large FOVs with high spatial resolution, and to fully capture substrate uptake and metabolic conversion, fast data acquisition is crucial. Parallel imaging uses multi-channel coils to achieve reduced...... scan times based on spatial information inherent to each coil element. In this work, we explored the combination of non-cartesian parallel imaging reconstruction and spatially undersampled IDEAL spiral CSI1 acquisition for efficient encoding of multiple chemical shifts within a large FOV with high...

  5. Present status of development of NMR imaging devices

    Energy Technology Data Exchange (ETDEWEB)

    Hatta, Junichi; Yazaki, Takehito; Abe, Yuzo; Komoike, Mitsutaka (Sanyo Electric Co. Ltd., Moriguchi, Osaka (Japan))

    1981-12-01

    The NMR spectrum of the protons in a graded magnetic field contains information on the distribution of water within the specimen. A system to process such information was made on trial, and examples of the cross-sections of a champignon, okra, lotus root and green onion are given. These proton density distribution images, i.e., the density distribution images of water have the highest resolution among those obtained to date in Japan. Studies are reported to be underway to improve the precision of this instrument and to enlarge its scale. The technical problems in obtaining an image of the relaxation time distribution, which has been proposed to be helpful in diagnosing cancer, are discussed. The present state of research in this field is reviewed.

  6. Anatomy of the bronchial arteries: imaging via spiral CT. Anatomie der Bronchialarterien - Darstellung mit der Spiral-CT

    Energy Technology Data Exchange (ETDEWEB)

    Schwickert, H.C. (Universitaetskliniken, Mainz (Germany). Klinik mit Poliklinik fuer Radiologie); Kauczor, H.U. (Universitaetskliniken, Mainz (Germany). Klinik mit Poliklinik fuer Radiologie); Schweden, F. (Universitaetskliniken, Mainz (Germany). Klinik mit Poliklinik fuer Radiologie); Schild, H.H. (Universitaetskliniken, Mainz (Germany). Klinik mit Poliklinik fuer Radiologie)

    1994-06-01

    The purpose of our study was to evaluate the capability of spiral CT in detecting bronchial arteries and in classifying their anatomic variations. Patients and Methods: In 43 patients with different diseases routine spiral CTs of the chest were performed and evaluated retrospectively. Spiral CT was started with a delay of 30 seconds after contrast material application. Results: In 43 patients a total of 67 bronchial arteries were detected: 31 right, 35 left and one common trunk. 26 right bronchial arteries originated medially, 5 anteriorly from the descending aorta, 7 of them together with an intercostal artery. 25 right bronchial arteries passed dorsally, 6 ventrally to the oesophagus. On the left, all 35 bronchial arteries originated from the anterior aorta: 12 led ventrally through the aorticopulmonary window to the ventral wall of the main bronchus, 14 were directed caudally to the cranial and 9 laterally to the posterior aspect of the main bronchus. The discernible length varied between 15 and 90 mm on the right, and between 10 and 37 mm on the left side. Only in two cases did the proximal diameter measure more than 2 mm. Conclusion: Spiral CT offers the possibility to classify the anatomic course and pathologic changes of the bronchial arteries. (orig.)

  7. An Atlas of Hubble Space Telescope Spectra and Images of Nearby Spiral Galaxies

    Science.gov (United States)

    Hughes, M. A.; Alonso-Herrero, A.; Axon, D.; Scarlata, C.; Atkinson, J.; Batcheldor, D.; Binney, J.; Capetti, A.; Carollo, C. M.; Dressel, L.; Gerssen, J.; Macchetto, D.; Maciejewski, W.; Marconi, A.; Merrifield, M.; Ruiz, M.; Sparks, W.; Stiavelli, M.; Tsvetanov, Z.; van der Marel, R.

    2003-08-01

    We have observed 54 nearby spiral galaxies with the Space Telescope Imaging Spectrograph (STIS) on the Hubble Space Telescope to obtain optical long-slit spectra of nuclear gas disks and STIS optical (~R band) images of the central 5''×5'' of the galaxies. These spectra are being used to determine the velocity field of nuclear disks and hence to detect the presence of central massive black holes. Here we present the spectra for the successful observations. Dust obscuration can be significant at optical wavelengths, and so we also combine the STIS images with archival Near-Infrared Camera and Multi-Object Spectrometer H-band images to produce color maps to investigate the morphology of gas and dust in the central regions. We find a great variety in the different morphologies, from smooth distributions to well-defined nuclear spirals and dust lanes. Based on observations with the NASA/ESA Hubble Space Telescope obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555.

  8. Single shot whole brain imaging using spherical stack of spirals trajectories.

    Science.gov (United States)

    Assländer, Jakob; Zahneisen, Benjamin; Hugger, Thimo; Reisert, Marco; Lee, Hsu-Lei; LeVan, Pierre; Hennig, Jürgen

    2013-06-01

    MR-encephalography allows the observation of functional signal in the brain at a frequency of 10 Hz, permitting filtering of physiological "noise" and the detection of single event activations. High temporal resolution is achieved by the use of undersampled non-Cartesian trajectories, parallel imaging and regularized image reconstruction. MR-encephalography is based on 3D-encoding, allowing undersampling in two dimensions and providing advantages in terms of signal to noise ratio. Long readout times, which are necessary for single shot whole brain imaging (up to 75 ms), cause off-resonance artifacts. To meet this issue, a spherical stack of spirals trajectory is proposed in this work. By examining the trajectories in local k-space, it is shown that in areas of strong susceptibility gradients spatial information is fundamentally lost, making a meaningful image reconstruction impossible in the affected areas. It is shown that the loss of spatial information is reduced when using a stack of spirals trajectory compared to concentric shells.

  9. Application of spiral CT image 3D reconstruction in severe talar neck fracture

    Institute of Scientific and Technical Information of China (English)

    HE Fei; HUANG He; DENG Ya-min; Wang Bing; ZHANG Chun-qiang; ZHAO Zhi; TANG Xi-zhang; ZHOU Zhao-wen; ZHAO Xue-ling

    2007-01-01

    Objective:To explore the application of the spiral computerized tomography (CT) image three-dimensional(3D ) reconstruction technique associated with the conventional radiography in the diagnosis and treatment of severe talar neck fracture. Methods:Using the multi-slice spiral CT image 3D reconstruction technique,we analysed 11 cases of talar neck fracture.The fractures were reduced and fixed through a minimal incision and internal fixation with titanium cannulated lag screws. Results:In the 11 cases,the results of CT image 3D reconstruction were in concordance with plain radiograph in 6 case of Hawkins type H.And the remaining 5 cases of Hawkins types Ⅲ and Ⅳ could not be classified exactly only by radiographs,one of whom was misdiagnosed.After using the CT image 3D reconstruction,the 5 cases were classified exactly before osteosynthesis.The classifications of these 11 cases were confirmed finally by surgical findings.The duration of operation were 45-140 min,averaging 81min (including the duration of C-arm fluoroscopy).X-ray exposure time was 6-58 seconds,averaging 22 seconds.The blood loss was less than 100 ml.The fracture union was achieved in 3 months. No nonunion, talus avascular necrosis or joint surface collapse occurred.Postoperative follow-up was from 1 to 25 months.According to Hawkins score,excellent result was found in 6 type Ⅱ cases and 1type Ⅲ case;good result in 1 type Ⅲ case with both medial and lateral malleolar fracture,1 type Ⅲ with medial malleolus fractures and 1 open type Ⅲ;fair result in 1 open type Ⅳ with lateral malleolus fracture. Conclusions:By using the multi-slice spiral CT image 3D reconstruction associated with radiography to diagnose and treat severe talar neck fractures,the accuracy of diagnosis can be improved obviously. Based on this technique,more consummate operational plan can be designed and performed so as to achieve a better therapeutic effect.

  10. Direct imaging of rf waveguide modes via ultra-high field NMR

    CERN Document Server

    Tonyushkin, A; Van de Moortele, P -F; Adriany, G; Kiruluta, A

    2016-01-01

    We demonstrate an experimental method for direct 2D and 3D imaging of magnetic rf field distribution in metal waveguides based on traveling wave (TW) nuclear-magnetic resonance (NMR) imaging at ultra-high field (>7T). The typical apparatus would include an ultra-high field whole body or small bore NMR scanner, waveguide elements filled with NMR active dielectrics with predefined electric and magnetic properties, and TW rf transmit-receive probes. We validated the technique by obtaining TW magnetic-resonance (MR) images of the magnetic field distribution of the rf modes of circular waveguide filled with deionized water in a 16.4 T small-bore NMR scanner and compared the MR images with numerical simulations. Our NMR technique opens up a practical way of imaging of previously inaccessible rf field distribution of modes inside of various shapes metal waveguides with inserted dielectric objects, including waveguide mode converters and transformers.

  11. Single NMR image super-resolution based on extreme learning machine.

    Science.gov (United States)

    Wang, Zhiqiong; Xin, Junchang; Wang, Zhongyang; Tian, Shuo; Qiu, Xuejun

    2016-10-01

    The performance limitation of MRI equipment and higher resolution demand of NMR images from radiologists have formed a strong contrast. Therefore, it is important to study the super resolution algorithm suitable for NMR images, using low costs software to replace the expensive equipment-updating. Firstly, a series of NMR images are obtained from original NMR images with original noise to the lowest resolution images with the highest noise. Then, based on extreme learning machine, the mapping relation model is constructed from lower resolution NMR images with higher noise to higher resolution NMR images with lower noise in each pair of adjacent images in the obtained image sequence. Finally, the optimal mapping model is established by the ensemble way to reconstruct the higher resolution NMR images with lower noise on the basis of original resolution NMR images with original noise. Experiments are carried out by 990111 NMR brain images in datasets NITRC, REMBRANDT, RIDER NEURO MRI, TCGA-GBM and TCGA-LGG. The performance of proposed method is compared with three approaches through 7 indexes, and the experimental results show that our proposed method has a significant improvement. Since our method considers the influence of the noise, it has 20% higher in Peak-Signal-to-Noise-Ratio comparison. As our method is sensitive to details, and has a better characteristic retention, it has higher image quality upgrade of 15% in the additional evaluation. Finally, since extreme learning machine has a celerity learning speed, our method is 46.1% faster. Copyright © 2016 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  12. Faster dynamic imaging of speech with field inhomogeneity corrected spiral fast low angle shot (FLASH) at 3 T.

    Science.gov (United States)

    Sutton, Bradley P; Conway, Charles A; Bae, Youkyung; Seethamraju, Ravi; Kuehn, David P

    2010-11-01

    To evaluate the impact of magnetic field inhomogeneity correction on achievable imaging speeds for magnetic resonance imaging (MRI) of articulating oropharyngeal structures during speech and to determine if sufficient acquisition speed is available for visualizing speech structures with real-time MRI. We designed a spiral fast low angle shot (FLASH) sequence that combines several acquisition techniques with an advanced image reconstruction approach that includes magnetic field inhomogeneity correction. A simulation study was performed to examine the interaction between imaging speed, image quality, number of spiral shots, and field inhomogeneity correction. Six volunteer subjects were scanned to demonstrate adequate visualization of articulating structures during simple speech samples. The simulation study confirmed that magnetic field inhomogeneity correction improves the available tradeoff between image quality and speed. Our optimized sequence co-acquires magnetic field maps for image correction and achieves a dynamic imaging rate of 21.4 frames per second, significantly faster than previous studies. Improved visualization of anatomical structures, such as the soft palate, was also seen from the field-corrected reconstructions in data acquired on volunteer subjects producing simple speech samples. Adequate temporal resolution of articulating oropharyngeal structures during speech can be obtained by combining outer volume suppression, multishot spiral imaging, and magnetic field corrected image reconstruction. Correcting for the large, dynamic magnetic field variation in the oropharyngeal cavity improves image quality and allows for higher temporal resolution. © 2010 Wiley-Liss, Inc.

  13. A substructure inside spiral arms, and a mirror image across the Galactic Meridian

    CERN Document Server

    Vallee, Jacques P

    2016-01-01

    While the galactic density wave theory is over 50 years old and well known in science, whether it fits our own Milky Way disk has been difficult to say. Here we show a substructure inside the spiral arms. This substructure is reversing with respect to the Galactic Meridian (longitude zero), and crosscuts of the arms at negative longitudes appear as mirror images of crosscuts of the arms at positive longitudes. Four lanes are delineated: mid-arm (extended 12CO gas at mid arm, HI atoms), in-between offset by about 100 pc (synchrotron, radio recombination lines), in between offset by about 200 pc (masers, colder dust), and inner edge (hotter dust seen in Mid-IR and Near-IR).

  14. Four Highly Luminous Massive Star Forming Regions in the Norma Spiral Arm II. Deep NIR imaging

    CERN Document Server

    Chavarria, L; Garay, G; Escala, A; Bronfman, L; Lizano, S

    2009-01-01

    We present sensitive NIR (J, H and K) imaging observations toward four luminous massive star forming regions in the Norma Spiral Arm: G324.201+0.119, G328.307+0.432, G329.337+0.147 and G330.949-0.174. We identify three clusters of young stellar objects (YSO) based on surface density diagnostics. We also find that sources detected only in the H and K-bands and with colors corresponding to spectral types earlier than B2, are likely YSOs. We analyze the spatial distribution of stars of different masses and find signatures in two clusters of primordial mass segregation which can't be explained as due to incompleteness effects. We show that dynamic interactions of cluster members with the dense gas from the parent core can explain the observed mass segregation, indicating that the gas plays an important role in the dynamics of young clusters.

  15. Study on 64-layer Spiral Computed Tomography Perfusion Imaging in Patients with Fatty Liver

    Institute of Scientific and Technical Information of China (English)

    RAO Xiao-hui; SU Qi; CAI Lei; QIN Jia-sheng; CAI Li-quan; HONG He; WANG Kang-hua; AI Zhi-guo; ZHANG Sheng

    2014-01-01

    Objective:To analyze the changes of hemodynamics of patients with fatty liver by detecting their blood perfusion parameter changes with Philips Brilliance 64-layer spiral computed tomography (CT) perfusion technique. Methods: A total of 74 patients undergoing 64-layer spiral CT perfusion imaging were selected as study objects, in which 39 were with fatty liver and the other 35 were healthy people. The parameters of liver blood perfusion were observed. Results: Hepatic arterial perfusion (Art.Perf), portal perfusion (Port.Perf) and total perfusion (Total.Perf) values as well as hepatic perfusion index (HPI) were (18.4±4.1), (71.5±14.2) and (93.2±6.7) mL/100 g·min as well as (25.15±5.22)% in control group, in which the Art.Perf, Port.Perf and Total.Perf were in close association with the severity of fatty liver and of great significance. Art.Perf of patients with mild, moderate and severe fatty liver was (15.4±4.0), (7.3±9.6) and (4.1±1.3) mL/100 g·min, Port.Perf was (56.5±10.7), (48.6±6.8) and (37.0±4.1) mL/100 g·min and Total.Perf was (71.3±5.7), (55.7±5.8) and (40.2±5.0) mL/100 g·min, respectively. However, HPI could not be considered as the evaluation index for the severity of fatty liver. Conclusion:CT perfusion imaging of liver can relfect blood changes of patients with fatty liver, which can be used to evaluate their blood-supply condition, thus providing more diagnostic evidences for the clinic.

  16. Study on 64-layer Spiral Computed Tomography Perfusion Imaging in Patients with Fatty Liver

    Directory of Open Access Journals (Sweden)

    RAO Xiao-hui

    2014-12-01

    Full Text Available Objective: To analyze the changes of hemodynamics of patients with fatty liver by detecting their blood perfusion parameter changes with Philips Brilliance 64-layer spiral computed tomography (CT perfusion technique. Methods: A total of 74 patients undergoing 64-layer spiral CT perfusion imaging were selected as study objects, in which 39 were with fatty liver and the other 35 were healthy people. The parameters of liver blood perfusion were observed. Results: Hepatic arterial perfusion (Art.Perf, portal perfusion (Port.Perf and total perfusion (Total.Perf values as well as hepatic perfusion index (HPI were (18.4±4.1, (71.5±14.2 and (93.2±6.7 mL/100 g·min as well as (25.15±5.22% in control group, in which the Art.Perf, Port.Perf and Total.Perf were in close association with the severity of fatty liver and of great significance. Art.Perf of patients with mild, moderate and severe fatty liver was (15.4±4.0, (7.3±9.6 and (4.1±1.3 mL/100 g·min, Port.Perf was (56.5±10.7, (48.6±6.8 and (37.0±4.1 mL/100 g·min and Total.Perf was (71.3±5.7, (55.7±5.8 and (40.2±5.0 mL/100 g·min, respectively. However, HPI could not be considered as the evaluation index for the severity of fatty liver. Conclusion: CT perfusion imaging of liver can reflect blood changes of patients with fatty liver, which can be used to evaluate their blood-supply condition, thus providing more diagnostic evidences for the clinic.

  17. Experimental Study of Multi-slice Spiral CT Perfusion Imaging in VX2 Soft-tissue Tumor of Rabbits

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jingfeng; WANG Renfa; WANG Min; LI Yonggang; YANG Haitao

    2006-01-01

    An experimental animal model of malignant soft-tissue tumor was established to investigate the applied value of multi-slice spiral CT perfusion imaging preliminarily. Ten New Zealand white rabbits which were implanted with VX2 tumor in either proximal thigh were subjected to CT plain scan and perfusion scan two weeks later respectively, then the original perfusion images were transmitted to AW4.0 Workstation. The functional maps and perfusion parameters including blood flow (BF), blood volume (BV), mean transit time (MTT) and permeability surface (PS) were computed and analyzed. All the values of BF, BV and PS in VX2 soft-tissue tumors were obviously higher while the MTT-values were lower than those in the normal muscular tissues significantly. It was suggested that multi-slice spiral CT perfusion imaging is an accurate, convenient and relatively safe functional imaging technique, and can give a quantitative assessment to angiogenesis and blood perfusion of soft-tissue tumors.

  18. Highest redshift neutral hydrogen image in emission: A CHILES detection of a starbursting spiral

    Science.gov (United States)

    Fernandez, Ximena; Van Gorkom, Jacqueline H.; Gim, Hansung; Yun, Min Su; Momjian, Emmanuel; CHILES Team

    2016-01-01

    Our current understanding of galaxy evolution still has many uncertainties associated with the details of gas accretion, processing, and removal across cosmic time. The next generation of radio telescopes will image the neutral hydrogen in galaxies over large volumes at high redshifts, which will provide key insights into these processes. We are conducting the COSMOS HI Large Extragalactic Survey (CHILES) with the VLA, which is the first survey to simultaneously observe HI from z=0 to z=0.5. The full survey consists of 1002 hours of observing time, giving us the sensitivity to image HI in 300 galaxies in the COSMOS field. Here, we report the highest redshift HI detection to date, the LIRG COSMOS J100054.83+023126.2 at z=0.376 with the first 178 hours of CHILES data. While the optical image shows it to be a large undisturbed spiral, the HI distribution is very extended and offset from the optical center. This could be evidence for interactions with companions or accretion fueling the starburst. In addition, we present follow-up LMT CO observations that reveal it to be gas-rich in molecular hydrogen. This is the first study of the HI and CO for a galaxy beyond the local Universe, which will enable us to start exploring the ISM of LIRGs at higher redshift.

  19. High-speed spiral imaging technique for an atomic force microscope using a linear quadratic Gaussian controller

    Science.gov (United States)

    Habibullah, H.; Pota, H. R.; Petersen, I. R.

    2014-03-01

    This paper demonstrates a high-speed spiral imaging technique for an atomic force microscope (AFM). As an alternative to traditional raster scanning, an approach of gradient pulsing using a spiral line is implemented and spirals are generated by applying single-frequency cosine and sine waves of slowly varying amplitudes to the X and Y-axes of the AFM's piezoelectric tube scanner (PTS). Due to these single-frequency sinusoidal input signals, the scanning process can be faster than that of conventional raster scanning. A linear quadratic Gaussian controller is designed to track the reference sinusoid and a vibration compensator is combined to damp the resonant mode of the PTS. An internal model of the reference sinusoidal signal is included in the plant model and an integrator for the system error is introduced in the proposed control scheme. As a result, the phase error between the input and output sinusoids from the X and Y-PTSs is reduced. The spirals produced have particularly narrow-band frequency measures which change slowly over time, thereby making it possible for the scanner to achieve improved tracking and continuous high-speed scanning rather than being restricted to the back and forth motion of raster scanning. As part of the post-processing of the experimental data, a fifth-order Butterworth filter is used to filter noises in the signals emanating from the position sensors and a Gaussian image filter is used to filter the images. A comparison of images scanned using the proposed controller (spiral) and the AFM PI controller (raster) shows improvement in the scanning rate using the proposed method.

  20. High-speed spiral imaging technique for an atomic force microscope using a linear quadratic Gaussian controller

    Energy Technology Data Exchange (ETDEWEB)

    Habibullah, H., E-mail: h.habib@student.adfa.edu.au; Pota, H. R., E-mail: h.pota@adfa.edu.au; Petersen, I. R., E-mail: i.petersen@adfa.edu.au [School of Engineering and Information Technology, University of New South Wales, Canberra, Australian Capital Territory 2612 (Australia)

    2014-03-15

    This paper demonstrates a high-speed spiral imaging technique for an atomic force microscope (AFM). As an alternative to traditional raster scanning, an approach of gradient pulsing using a spiral line is implemented and spirals are generated by applying single-frequency cosine and sine waves of slowly varying amplitudes to the X and Y-axes of the AFM’s piezoelectric tube scanner (PTS). Due to these single-frequency sinusoidal input signals, the scanning process can be faster than that of conventional raster scanning. A linear quadratic Gaussian controller is designed to track the reference sinusoid and a vibration compensator is combined to damp the resonant mode of the PTS. An internal model of the reference sinusoidal signal is included in the plant model and an integrator for the system error is introduced in the proposed control scheme. As a result, the phase error between the input and output sinusoids from the X and Y-PTSs is reduced. The spirals produced have particularly narrow-band frequency measures which change slowly over time, thereby making it possible for the scanner to achieve improved tracking and continuous high-speed scanning rather than being restricted to the back and forth motion of raster scanning. As part of the post-processing of the experimental data, a fifth-order Butterworth filter is used to filter noises in the signals emanating from the position sensors and a Gaussian image filter is used to filter the images. A comparison of images scanned using the proposed controller (spiral) and the AFM PI controller (raster) shows improvement in the scanning rate using the proposed method.

  1. High-speed spiral imaging technique for an atomic force microscope using a linear quadratic Gaussian controller.

    Science.gov (United States)

    Habibullah, H; Pota, H R; Petersen, I R

    2014-03-01

    This paper demonstrates a high-speed spiral imaging technique for an atomic force microscope (AFM). As an alternative to traditional raster scanning, an approach of gradient pulsing using a spiral line is implemented and spirals are generated by applying single-frequency cosine and sine waves of slowly varying amplitudes to the X and Y-axes of the AFM's piezoelectric tube scanner (PTS). Due to these single-frequency sinusoidal input signals, the scanning process can be faster than that of conventional raster scanning. A linear quadratic Gaussian controller is designed to track the reference sinusoid and a vibration compensator is combined to damp the resonant mode of the PTS. An internal model of the reference sinusoidal signal is included in the plant model and an integrator for the system error is introduced in the proposed control scheme. As a result, the phase error between the input and output sinusoids from the X and Y-PTSs is reduced. The spirals produced have particularly narrow-band frequency measures which change slowly over time, thereby making it possible for the scanner to achieve improved tracking and continuous high-speed scanning rather than being restricted to the back and forth motion of raster scanning. As part of the post-processing of the experimental data, a fifth-order Butterworth filter is used to filter noises in the signals emanating from the position sensors and a Gaussian image filter is used to filter the images. A comparison of images scanned using the proposed controller (spiral) and the AFM PI controller (raster) shows improvement in the scanning rate using the proposed method.

  2. In vivo quantitative NMR imaging of fruit tissues during growth using Spoiled Gradient Echo sequence

    DEFF Research Database (Denmark)

    Kenouche, S.; Perrier, M.; Bertin, N.;

    2014-01-01

    Nondestructive studies of physiological processes in agronomic products require increasingly higher spatial and temporal resolutions. Nuclear Magnetic Resonance (NMR) imaging is a non-invasive technique providing physiological and morphological information on biological tissues. The aim of this s...

  3. NMR relaxation and micro-imaging study of polystyrene in concentrated cyclohexane solution

    Institute of Scientific and Technical Information of China (English)

    毛诗珍; 丁广良; 袁汉珍; 冯汉桥; 杜有如

    1997-01-01

    13C-NMR relaxation times of polystyrene (PS) in its 8 solvent, cyclohexane, are measured at different temperatures. A two-step model for the dissolution is proposed. Swelling of the polymer below the 8 temperature is eventually the dispersion of the side group phenyl rings only. While above the 6 temperature, complete dissolution is the dispersion of the main chain at a molecular level. The results of T1(C) are confirmed by 1H-NMR imaging. NMR and its imaging are powerful tools to study the dynamic behavior of dissolution process of polymers in their 6 solvents.

  4. The DiskMass Survey. X. Radio synthesis imaging of spiral galaxies

    CERN Document Server

    Martinsson, Thomas P K; Bershady, Matthew A; Westfall, Kyle B; Andersen, David R; Swaters, Rob A

    2016-01-01

    We present results from 21 cm radio synthesis imaging of 28 spiral galaxies from the DiskMass Survey obtained with the VLA, WSRT, and GMRT facilities. We detail the observations and data reduction procedures and present a brief analysis of the radio data. We construct 21 cm continuum images, global HI emission-line profiles, column-density maps, velocity fields, and position-velocity diagrams. From these we determine star formation rates (SFRs), HI line widths, total HI masses, rotation curves, and azimuthally-averaged radial HI column-density profiles. All galaxies have an HI disk that extends beyond the readily observable stellar disk, with an average ratio and scatter of R_{HI}/R_{25}=1.35+/-0.22, and a majority of the galaxies appear to have a warped HI disk. A tight correlation exists between total HI mass and HI diameter, with the largest disks having a slightly lower average column density. Galaxies with relatively large HI disks tend to exhibit an enhanced stellar velocity dispersion at larger radii, ...

  5. Spirality: A Noval Way to Measure Spiral Arm Pitch Angle

    Science.gov (United States)

    Shields, Douglas; Arkansas Galaxy Evolution Survey

    2017-01-01

    We present the MATLAB code Spirality, a novel method for measuring spiral arm pitch angles by fitting galaxy images to spiral templates of known pitch. Computation time is typically on the order of 2 minutes per galaxy, assuming 8 GB of working memory. We tested the code using 117 synthetic spiral images with known pitches, varying both the spiral properties and the input parameters. The code yielded correct results for all synthetic spirals with galaxy-like properties. We also compared the code’s results to two-dimensional Fast Fourier Transform (2DFFT) measurements for the sample of nearby galaxies defined by DMS PPak. Spirality’s error bars overlapped 2DFFT’s error bars for 26 of the 30 galaxies. The two methods’ agreement correlates strongly with galaxy radius in pixels and also with i-band magnitude, but not with redshift, a result that is consistent with at least some galaxies’ spiral structure being fully formed by z=1.2, beyond which there are few galaxies in our sample. We also analyze apparent spiral structure of three galaxies beyond z=2. The Spirality code package also includes GenSpiral, which produces FITS images of synthetic spirals, and SpiralArmCount, which uses a one-dimensional Fast Fourier Transform to count the spiral arms of a galaxy after its pitch is determined.

  6. Fast method of NMR imaging based on trains of spin echoes

    Energy Technology Data Exchange (ETDEWEB)

    Hennel, F.

    1993-12-31

    A theoretical introduction to Fourier NMR imaging and a discussion of fast methods are presented. Then an application of the method of echo-planar imaging (EPI) with spin echoes in a micro-imaging system is described together with introduced modifications of the sequence. A new technique for the measurement of flow profiles in liquids which results from a modification of x-pulsed EPI is presented. The development of new software for a NMR micro-imaging system is described, too. 51 refs, 29 refs.

  7. NON-INVASIVE IMAGING OF CORONARY ARTERY WITH 16-SLICE SPIRAL COMPUTED TOMOGRAPHY

    Institute of Scientific and Technical Information of China (English)

    Zhu-hua Zhang; Wen-bin Mou; Li-Ren Zhang; Wen-ling Zhu; Chao Ni; Hua Ren; Hong-quan Yu; Qi Miao; Qi Fang; Zheng-yu Jin; Dong-jing Li; Song-bai Lin; Shu-yang Zhang; Ling-yan Kong; Yun Wang; Lin-hui Wang; Wen-min Zhao

    2004-01-01

    Objective To evaluate the value of 16-slice spiral CT in the demonstration of coronary artery and in the diagnose of coronary artery stenosis.Methods Plain and enhanced CT scans were performed with a 16-slice CT scanner (Sensation 16, Siemens, Germany)in 230 patients with suspected coronary heart disease (CHD). Parameters of the plain scan were: 120 kV, 133 mA, slice collimation 16 mm×1.5 mm, rotation time 0.42 seconds, increment 1.5 mm, and slice width 3 mm. Parameters of the enhanced scan were: 120 kV, 500 mA, slice collimation 16 mm×0.75 mm, rotation time 0.42 seconds, increment 0.5 mm, and slice width 1 mm. Enhanced CT scan was performed with a rapid intravenous injection of 100 mL iothalamate meglumine (Ultravist)(370 mgI/mL) or Omnipaque (350mgI/mL) and 30 mL 0.9% NaC1 chaser bolus at a flow rate of 3.5 mL/s. Calcium scoring with plain scan images and two and three dimensional reconstruction with enhanced scan images were made in all cases,among which 30 cases underwent conventional coronary angiography. Demonstration of coronary arteries and their stenosis were evaluated and the factors that might influence the image quality were analyzed.Results Coronary calcium scores were calculated and coronary artery was demonstrated in our study. In the evaluation of image quality with volume rendering technique (VRT) images, 78.3% of the images were of the first class, 12.2% the second class, and 9.6% the third class. Multi-planar reconstruction (MPR) and maximal intensity projection (MIP) were better than VRT in the demonstration of small branches. The image quality was related to the heart rate, with or without arrhythmia,and breath-hold ability of patients. Comparative study of the stenosis of coronary arteries in 30 cases showed that the sensitivity and specificity of 16-slice coronary CT angiography (CTA) to diagnose significant stenosis were 95.8% and 94.8% respectively.Conclusion As a non-invasive and quick method, 16-slice coronary CTA is sensitive and

  8. Imaging Three-Dimensional Myocardial Mechanics Using Navigator-gated Volumetric Spiral Cine DENSE MRI

    Science.gov (United States)

    Zhong, Xiaodong; Spottiswoode, Bruce S.; Meyer, Craig H.; Kramer, Christopher M.; Epstein, Frederick H.

    2010-01-01

    A navigator-gated 3D spiral cine displacement encoding with stimulated echoes (DENSE) pulse sequence for imaging 3D myocardial mechanics was developed. In addition, previously-described 2D post-processing algorithms including phase unwrapping, tissue tracking, and strain tensor calculation for the left ventricle (LV) were extended to 3D. These 3D methods were evaluated in 5 healthy volunteers, using 2D cine DENSE and historical 3D myocardial tagging as reference standards. With an average scan time of 20.5 ± 5.7 minutes, 3D data sets with a matrix size of 128 × 128 × 22, voxel size of 2.8 × 2.8 × 5.0 mm3, and temporal resolution of 32 ms were obtained with displacement encoding in three orthogonal directions. Mean values for end-systolic mid-ventricular mid-wall radial, circumferential, and longitudinal strain were 0.33 ± 0.10, −0.17 ± 0.02, and −0.16 ± 0.02, respectively. Transmural strain gradients were detected in the radial and circumferential directions, reflecting high spatial resolution. Good agreement by linear correlation and Bland-Altman analysis was achieved when comparing normal strains measured by 2D and 3D cine DENSE. Also, the 3D strains, twist, and torsion results obtained by 3D cine DENSE were in good agreement with historical values measured by 3D myocardial tagging. PMID:20574967

  9. High-Resolution Multi-Shot Spiral Diffusion Tensor Imaging with Inherent Correction of Motion-Induced Phase Errors

    Science.gov (United States)

    Truong, Trong-Kha; Guidon, Arnaud

    2014-01-01

    Purpose To develop and compare three novel reconstruction methods designed to inherently correct for motion-induced phase errors in multi-shot spiral diffusion tensor imaging (DTI) without requiring a variable-density spiral trajectory or a navigator echo. Theory and Methods The first method simply averages magnitude images reconstructed with sensitivity encoding (SENSE) from each shot, whereas the second and third methods rely on SENSE to estimate the motion-induced phase error for each shot, and subsequently use either a direct phase subtraction or an iterative conjugate gradient (CG) algorithm, respectively, to correct for the resulting artifacts. Numerical simulations and in vivo experiments on healthy volunteers were performed to assess the performance of these methods. Results The first two methods suffer from a low signal-to-noise ratio (SNR) or from residual artifacts in the reconstructed diffusion-weighted images and fractional anisotropy maps. In contrast, the third method provides high-quality, high-resolution DTI results, revealing fine anatomical details such as a radial diffusion anisotropy in cortical gray matter. Conclusion The proposed SENSE+CG method can inherently and effectively correct for phase errors, signal loss, and aliasing artifacts caused by both rigid and nonrigid motion in multi-shot spiral DTI, without increasing the scan time or reducing the SNR. PMID:23450457

  10. Nuclear magnetic resonance (NMR) imaging of Arnold-Chiari type I malformation with hydromyelia

    Energy Technology Data Exchange (ETDEWEB)

    DeLaPaz, R.L.; Brady, T.J.; Buonanno, F.S.; New, P.F.; Kistler, J.P.; McGinnis, B.D.; Pykett, I.L.; Taveras, J.M.

    1983-02-01

    Saturation recovery nuclear magnetic resonance (NMR) images and metrizamide computed tomography (CT) scans were obtained in an adult patient with a clinical history suggestive of syringomyelia. Both NMR and CT studies showed low lying cerebellar tonsils. The CT study demonstrated central cavitation of the spinal cord from the midthoracic to midcervical levels but could not exclude an intramedullary soft tissue mass at the cervico-medullary junction. The NMR images in transverse, coronal, and sagittal planes demonstrated extension of an enlarged central spinal cord cerebrospinal fluid space to the cervico-medullary junction. This was felt to be strong evidence for exclusion of an intramedullary soft tissue mass and in favor of a diagnosis of Arnold-Chiari Type I malformation with hydromyelia. The noninvasive nature of spinal cord and cervico-medullary junction evaluation with NMR is emphasized.

  11. Spherical long spirals

    Science.gov (United States)

    Georgiev, G. H.; Dinkova, C. L.

    2013-10-01

    Long spirals in the Euclidean plane have been introduced by A. Kurnosenko five years ago. Using a natural map of the shape sphere into the extended Gaussian plane we study spherical curves that are pre-images of plane long spirals. Loxodromes and spherical spiral antennas are typical examples of such spherical long spirals. The set of all planar spirals leaves invariant under an arbitrary similarity transformation. This set is divided in two disjoint classes by A. Kirnosenko. The first class is consist of the so-called short spirals which are widely used in geometric modeling. The second class of planar long spirals contains well-known logarithmic spiral and Archimedean spirals which have many applications in mathematics, astrophysics and industry. The notion of simplicial shape space is due to D. Kendall. The most popular simplicial shape space of order (2,3) is the set of equivalence classes of similar triangles in the plane. The sphere of radius 1/2 centered at the origin can be considered as a model of this quotient space, so-called the shape sphere. F. Bookstein and J. Lester showed that the one-point extension of the Euclidean plane, so-called the extended Gaussian plane, is another model of the same simplicial shape space. The present paper gives a description of long spirals on the shape sphere by the use a natural conformal mapping between two models. First, we examine long spirals in the extended Gaussian plane. After that, we describe some differential geometric properties of the shape sphere. Finally, we discuss parameterizations of long spirals on the shape sphere.

  12. A test of arm-induced star formation in spiral galaxies from near-IR and H$\\alpha$ imaging

    CERN Document Server

    Seigar, M S; Seigar, Marc S.; James, Phil A.

    2002-01-01

    We have imaged a sample of 20 spiral galaxies in H$\\alpha$ and in the near-infrared K band (2.2 um), in order to determine the location and strength of star formation in these objects with respect to perturbations in the old stellar population. We have found that star formation rates are significantly enhanced in the vicinity of K band arms. We have also found that this enhancement in star formation rate in arm regions correlates well with a quantity that measures the relative strengths of shocks in arms. Assuming that the K band light is dominated by emission from the old stellar population, this shows that density waves trigger star formation in the vicinity of spiral arms.

  13. Peripheral pulmonary nodules: Relationship between multi-slice spiral CT perfusion imaging and tumor angiogenesis and VEGF expression

    Directory of Open Access Journals (Sweden)

    Cheng Xiao-Ling

    2008-06-01

    Full Text Available Abstract Background The aim of this study is to investigate the relationship between16-slice spiral CT perfusion imaging and tumor angiogenesis and VEGF (vascular endothelial growth factor expression in patients with benign and malignant pulmonary nodules, and differential diagnosis between benign and malignant pulmonary nodules. Methods Sixty-four patients with benign and malignant pulmonary nodules underwent 16-slice spiral CT perfusion imaging. The CT perfusion imaging was analyzed for TDC (time density curve, perfusion parametric maps, and the respective perfusion parameters. Immunohistochemical findings of MVD (microvessel density measurement and VEGF expression was evaluated. Results The shape of the TDC of peripheral lung cancer was similar to those of inflammatory nodule. PH (peak height, PHpm/PHa (peak height ratio of pulmonary nodule to aorta, BF (blood flow, BV (blood volume value of peripheral lung cancer and inflammatory nodule were not statistically significant (all P > 0.05. Both showed significantly higher PH, PHpm/PHa, BF, BV value than those of benign nodule (all P 0.05. In the case of adenocarcinoma, BV, BF, PS, PHpm/PHa, and MVD between poorly and well differentiation and between poorly and moderately differentiation were statistically significant (all P 0.05. PH, PHpm/PHa, BV, and PS of benign nodule were significantly lower than those of peripheral lung cancer (all P Conclusion Multi-slice spiral CT perfusion imaging closely correlated with tumor angiogenesis and reflected MVD measurement and VEGF expression. It provided not only a non-invasive method of quantitative assessment for blood flow patterns of peripheral pulmonary nodules but also an applicable diagnostic method for peripheral pulmonary nodules.

  14. Multiplanar spiral CT enterography in patients with Crohn's disease using a negative oral contrast material: initial results of a noninvasive imaging approach

    Energy Technology Data Exchange (ETDEWEB)

    Reittner, Pia; Goritschnig, Toria; Doerfler, Otto [Department of Radiology, Karl Franzens Medical School and University Hospital Graz, Auenbruggerplatz 9, 8036 Graz (Austria); Petritsch, Wolfgang; Hinterleitner, Thomas [Department of Internal Medicine, Karl Franzens Medical School and University Hospital Graz, Auenbruggerplatz 9, 8036 Graz (Austria); Preidler, Klaus W.; Szolar, Dieter H. [Diagnostikum Graz Sued West, Weblinger Guertel 25, 8054 Graz (Austria)

    2002-09-01

    The aim of this study was to prospectively define the role of multiplanar spiral CT enterography with a new negative oral contrast material for noninvasive assessment of the small bowel in patients with Crohn's disease. Thirty patients with established Crohn's disease prospectively underwent spiral CT enterography at 45-60 min after distension of the small bowel with 1400 ml of a negative oral contrast material (Mucofalk water enema). Spiral CT scans were obtained 50 s after administration of intravenous contrast material with the following parameters: 5-mm collimation; 7.5-mm/s table feed; and 3-mm reconstruction interval. The adequacy of bowel opacification, luminal distension, and the contribution of two-dimensional multiplanar reformatted imaging were assessed by two observers. Spiral CT imaging findings were compared with results of enteroclysis as well as endoscopic and histological findings in all patients. Spiral CT enterography with Mucofalk water enema was well tolerated in 29 of 30 patients. Findings on spiral CT enterography were comparable with those of barium studies in 25 of 30 patients, superior to those on barium studies in 4 patients, and inferior in 1 patient (p<0.05). The addition of multiplanar reformatted images to axial spiral CT scans significantly improved observers' confidence in image interpretation (p<0.05) but did not reveal additional abnormalities. Multiplanar spiral CT enterography with Mucofalk excellently provides information in patients with Crohn's disease. This technique accurately depicts the level of small bowel obstruction and the extent of inflammatory small bowel disease and its extraluminal complications. (orig.)

  15. Tracking Target and Spiral Waves

    DEFF Research Database (Denmark)

    Jensen, Flemming G.; Sporring, Jon; Nielsen, Mads

    2002-01-01

    A new algorithm for analyzing the evolution of patterns of spiral and target waves in large aspect ratio chemical systems is introduced. The algorithm does not depend on finding the spiral tip but locates the center of the pattern by a new concept, called the spiral focus, which is defined...... by the evolutes of the actual spiral or target wave. With the use of Gaussian smoothing, a robust method is developed that permits the identification of targets and spirals foci independently of the wave profile. Examples of an analysis of long image sequences from experiments with the Belousov...

  16. Tracking Target and Spiral Waves

    DEFF Research Database (Denmark)

    Jensen, Flemming G.; Sporring, Jon; Nielsen, Mads;

    2002-01-01

    A new algorithm for analyzing the evolution of patterns of spiral and target waves in large aspect ratio chemical systems is introduced. The algorithm does not depend on finding the spiral tip but locates the center of the pattern by a new concept, called the spiral focus, which is defined...... by the evolutes of the actual spiral or target wave. With the use of Gaussian smoothing, a robust method is developed that permits the identification of targets and spirals foci independently of the wave profile. Examples of an analysis of long image sequences from experiments with the Belousov...

  17. Investigating human brain cognition using spiral imaging%基于螺旋成像的人脑认知功能研究

    Institute of Scientific and Technical Information of China (English)

    邵涵钰; 翁旭初

    2014-01-01

    Human brain cognition has been mostly investigated with single-short echo-planar imaging (EPI) in order to cover the whole brain within a few seconds. However, the duration of EPI readout is relatively long because it utilizes a Cartesian trajectory to cover k-space and only Gx gradient contributes to the trajectory. The longer duration can result in substantial artifacts from off-resonance and gradient imperfections. Moreover, EPI is sensitive to motion because the ifrst-and higher order moments of the gradient waveforms near the k-space origin is large. Here we present another fast imaging technique, namely spiral imaging for the study of human brain cognition. Spiral samples an Archimedean or similar trajectory to cover k-space that either begins at the k-space center and spirals to the edge (spiral-out), or begins at the edge and ends at the origin (spiral-in). The readout duration of spiral is shorter than that of EPI due to its efifcient use of both Gx and Gy gradients to drive the trajectory, and its sensitivity to motion is lower since the gradient moments are low at the center of k-space and increase slowly with time. Spiral is a promising imaging technique in terms of breaking the bottle neck in EPI study of human brain cognition. Speciifcally, the use of spiral-in/out trajectories in which a spiral-in readout is followed by a spiral-out can simultaneously increase the SNR in uniform brain regions as well as to reduce the signal dropout in regions compromised by susceptibility-induced ifeld gradients. Furthermore, a variable-density spiral, which consists of an Archimedean spiral from the space origin to a user-speciifed k-space radius and a undersampled variable density spiral from the speciifed points to the maximum radius, can achieve high temporal and spatial resolution fMRI without loss of SNR using single-short.%目前,人脑认知功能研究广泛使用平面回波成像(EPI)来快速扫描全脑。然而,EPI采用笛卡尔轨迹覆盖k空间

  18. In vivo quantitative NMR imaging of fruit tissues during growth using Spoiled Gradient Echo sequence

    DEFF Research Database (Denmark)

    Kenouche, S.; Perrier, M.; Bertin, N.

    2014-01-01

    of columella and in the seed envelopes. The total quantities and the average volume flow of water estimated are: 198 mg, 1.76 mm 3/h for the columella and 326 mg, 2.91 mm 3/h for the seed envelopes. We demonstrate in this paper that the NMR imaging technique coupled with efficient and biocompatible CA...

  19. Displacement imaging in porous media using the line scan NMR technique

    NARCIS (Netherlands)

    Dusschoten, van D.; Noort, van J.; As, van H.

    1997-01-01

    Displacement imaging is a recent, powerful NMR method with which distributions of displacements can be acquired of e.g. fluids within a porous medium. Both motion parallel and perpendicular to the flow direction may be observed within a time window of a few milliseconds to several seconds. By combin

  20. SPECT/spiral-CT hybrid imaging in unclear foci of increased bone metabolism: a case report

    Energy Technology Data Exchange (ETDEWEB)

    Roemer, W.; Kuwert, T. [Nuklearmedizinische Klinik, Friedrich-Alexander-Univ. Erlangen/Nuernberg (Germany); Beckmann, M.W. [Frauenklinik, Friedrich-Alexander-Univ. Erlangen/Nuernberg (Germany); Forst, R. [Lehrstuhl fuer Orthopaedie mit Orthopaedischer Chirurgie, Friedrich-Alexander Univ. Erlangen/Nuernberg (Germany); Bautz, W. [Radiologisches Inst., Friedrich-Alexander-Univ. Erlangen/Nuernberg (Germany)

    2005-07-01

    In bone scintigraphy, the differentiation between degenerative processes and bone metastases is still difficult. Therefore, additional radiological studies are regularly needed after bone scintigraphy. The now introduced hybrid-cameras combining single-photon emission computed tomography (SPECT) and spiral-CT are unique in the sense that they offer the opportunity to correlate the functional information with morphology in one session. We herein present two patients in whom this technological setup allowed a definite diagnosis in scintigraphically unclear vertebral lesions. In a patient with breast cancer, hypermetabolic lesions were clearly correlated with osteolyses. In another patient with synovial carcinoma, spondylosis and spondylarthrosis caused focal tracer uptake in the lumbar spine. In addition to an improved diagnostic accuracy, SPECT/Spiral-CT will considerably abbreviate the diagnostic process. (orig.)

  1. Spiral symmetry

    CERN Document Server

    Hargittai, Istvan

    1992-01-01

    From the tiny twisted biological molecules to the gargantuan curling arms of many galaxies, the physical world contains a startling repetition of spiral patterns. Today, researchers have a keen interest in identifying, measuring, and defining these patterns in scientific terms. Spirals play an important role in the growth processes of many biological forms and organisms. Also, through time, humans have imitated spiral motifs in their art forms, and invented new and unusual spirals which have no counterparts in the natural world. Therefore, one goal of this multiauthored book is to stress the c

  2. Detection of small hypervascular hepatocellular carcinomas in cirrhotic patients: comparison of superparamagnetic iron oxide-enhanced MR imaging with dual-phase spiral CT

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jeong Min [Seoul National University Hospital, Seoul (Korea, Republic of); Kim, In Hwan; Kwak, Hyo Sung; Youk, Ji Hyun; Han, Young Min; Kim, Chong Soo [Chonbuk National University, Chounju (Korea, Republic of)

    2003-03-01

    To compare the performance of superparamagnetic iron oxide (SPIO)-enhanced magnetic resonance (MR) imaging at 1.5T and dual-phase spiral computed tomography (CT) for the depiction of small hypervascular hepatocellular carcinomas (HCCs). Forty-three patients with 70 small nodular HCCs (5- 20 mm; mean, 13.7 mm) were examined. Diagnosis was based on the results of surgical biopsy in 22 patients and by the combined assessment of MR imaging, lipiodol CT, alpha feto-protein levels, and angiographic findings in 21. MR imaging consisted of respiratory-triggered turbo spin-echo T2-weighted imaging, T1- weighted fast low-angle shot, and T2* -weighted fast imaging with steady-state precession imaging before and after SPIO enhancement. CT imaging was performed with 5-mm collimation and 1:1.4 pitch, and began 30 and 65 secs after the injection of 150 mL of contrast medium at a rate of 3 mL/sec. Two blinded observers reviewed all images independently on a segment-by-segment basis. Diagnostic accuracy was evaluated using receiver operating characteristics (ROC) analysis. The mean areas (Az) under the ROC curves were 0.85 for SPIOenhanced MR imaging and 0.79 for dual-phase spiral CT (p < .05). The mean sensitivity of SPIO-enhanced MR imaging was significantly higher than that of CT (p < .05), i.e. 70.6% for MR imaging and 58.1% for CT. MR imaging had higher false-positive rates than dual-phase spiral CT, but the difference was not statistically significant (3.7% vs 3.3%) (p > .05). SPIO-enhanced MR imaging is more sensitive than dual-phase spiral CT for the depiction of small hypervascular hepatocellular carcinomas.

  3. Observational Signatures of Planets in Protoplanetary Disks: Spiral Arms Observed in Scattered Light Imaging Can be Induced by Planets

    CERN Document Server

    Dong, Ruobing; Rafikov, Roman; Stone, James

    2015-01-01

    Using 3D global hydro simulations coupled with radiative transfer calculations, we study the appearance of density waves induced by giant planets in direct imaging observations at near infrared wavelengths. We find that a 6 MJ planet in a typical disk around a 1 M_sun star can produce prominent and detectable spiral arms both interior and exterior to its orbit. The inner arms have (1) two well separated arms in roughly m=2 symmetry, (2) exhibit ~10-15 degrees pitch angles, (3) ~180-270 degrees extension in the azimuthal direction, and (4) ~150% surface brightness enhancement, all broadly consistent with observed spiral arms in the SAO 206462 and MWC 758 systems. The outer arms cannot explain observations as they are too tightly wound given typical disk scale height. We confirm previous results that the outer density waves excited by a 1 MJ planet exhibit low contrast in the IR and are practically not detectable. We also find that 3D effects of the waves are important. Compared to isothermal models, density wa...

  4. Methodological NMR imaging developments to measure cerebral perfusion; Developpements methodologiques en IRM pour la mesure de perfusion cerebrale

    Energy Technology Data Exchange (ETDEWEB)

    Pannetier, N.

    2010-12-15

    This work focuses on acquisition techniques and physiological models that allow characterization of cerebral perfusion by MRI. The arterial input function (AIF), on which many models are based, is measured by a technique of optical imaging at the carotid artery in rats. The reproducibility and repeatability of the AIF are discussed and a model function is proposed. Then we compare two techniques for measuring the vessel size index (VSI) in rats bearing a glioma. The reference technique, using a USPIO contrast agent (CA), faces the dynamic approach that estimates this parameter during the passage of a bolus of Gd. This last technique has the advantage of being used clinically. The results obtained at 4.7 T by both approaches are similar and use of VSI in clinical protocols is strongly encouraged at high field. The mechanisms involved (R1 and R2* relaxivities) were then studied using a multi gradient -echoes approach. A multi-echoes spiral sequence is developed and a method that allows the refocusing between each echo is presented. This sequence is used to characterize the impact of R1 effects during the passage of two successive injections of Gd. Finally, we developed a tool for simulating the NMR signal on a 2D geometry taking into account the permeability of the BBB and the CA diffusion in the interstitial space. At short TE, the effect of diffusion on the signal is negligible. In contrast, the effects of diffusion and permeability may be separated at long echo time. Finally we show that during the extravasation of the CA, the local magnetic field homogenization due to the decrease of the magnetic susceptibility difference at vascular interfaces is quickly balanced by the perturbations induced by the increase of the magnetic susceptibility difference at the cellular interfaces in the extravascular compartment. (author)

  5. Observational Signatures of Planets in Protoplanetary Disks: Spiral Arms Observed in Scattered Light Imaging Can be Induced by Planets

    Science.gov (United States)

    Dong, Ruobing; Zhu, Zhaohuan; Rafikov, Roman R.; Stone, James M.

    2015-08-01

    Using 3D global hydro simulations coupled with radiative transfer calculations, we study the appearance of density waves induced by giant planets in direct imaging observations at near-infrared wavelengths. We find that a 6{M}{{J}} planet in a typical disk around a 1{M}⊙ star can produce prominent and detectable spiral arms both interior and exterior to its orbit. The inner arms have (1) two well separated arms in roughly m = 2 symmetry, (2) exhibit ˜10°-15° pitch angles, (3) ˜180°-270° extension in the azimuthal direction, and (4) ˜ 150 % surface brightness enhancement, all broadly consistent with observed spiral arms in the SAO 206462 and MWC 758 systems. The outer arms cannot explain observations as they are too tightly wound given typical disk scale height. We confirm previous results that the outer density waves excited by a 1{M}{{J}} planet exhibit low contrast in the IR and are practically not detectable. We also find that 3D effects of the waves are important. Compared to isothermal models, density waves in adiabatic disks exhibit weaker contrast in surface density but stronger contrast in scattered light images, due to a more pronounced vertical structure in the former caused by shock heating and maybe hydraulic jump effect. To drive observed pairs of arms with an external companion on a circular orbit, a massive planet, possibly a brown dwarf, is needed at around [r˜ 0\\buildrel{\\prime\\prime}\\over{.} 7, {PA}˜ 10^\\circ ] (position angle PA from north to east) in SAO 206462 and [r˜ 0\\buildrel{\\prime\\prime}\\over{.} 6, {PA}˜ 10^\\circ ] in MWC 758. Their existence may be confirmed by direct imaging planet searches.

  6. Radio spectral index images of the spiral galaxies NGC 0628, NGC 3627, and NGC 7331

    CERN Document Server

    Paladino, R; Orrù, E

    2009-01-01

    In order to understand the cosmic ray propagation mechanism in galaxies, and its correlation with the sites of star formation, we compare the spatially resolved radio spectral index of three spiral galaxies with their IR distribution. We present new low-frequency radio continuum observations of the galaxies NGC 0628, NGC 3627, and NGC 7331, taken at 327 MHz with the Very Large Array. We complemented our data set with sensitive archival observations at 1.4 GHz and we studied the variations of the radio spectral index within the disks of these spiral galaxies. We also compared the spectral index distribution and the IR distribution, using 70 $\\mu$m Spitzer observations. We found that in these galaxies the non-thermal spectral index is anticorrelated with the radio brightness. Bright regions, like the bar in NGC 3627 or the circumnuclear region in NGC 7331, are characterized by a flatter spectrum with respect to the underlying disk. Therefore, a systematic steepening of the spectral index with the increasing dis...

  7. Diagnosis value of NMR imaging in recurring postoperative sciatica

    Energy Technology Data Exchange (ETDEWEB)

    Frocrain, L.; Duvauferrier, R.; Chales, G.; Ramee, A.; Pawlotsky, Y.

    1987-05-01

    Twelve patients who had a subsequent lumbar sciatica after surgery were evaluated with computerized tomography (C.T.) and magnetic resonance imaging (M.R.I.). The M.R.I. was performed with a 0.35 T whole body superconducting unit using spin echo technique. Two pulse sequences were realized varying the repetition time (TR) from 500 to 2,000 ms and the echo time (TE) from 28 to 60 ms. For the longer pulse, the twice echo were interpreted. The slide obtained with a surface-coil were performed in sagittal plane for the twice pulse sequences and in transaxial plane for the shorter pulse sequence. In seven cases, the results obtained with C.T. and M.R.I. were correlated. In two cases, the C.T. showed a scar formation, the M.R.I. showed a recurrent disk herniation. In three times, C.T. was unable to differentiate clearly between recurrent disk herniation and scar formation, the M.R.I. showed unequivocally on one case a scar formation and on two cases a recurrent disk herniation.

  8. Spirality: A Novel Way to Measure Spiral Arm Pitch Angle

    CERN Document Server

    Shields, Douglas W; Pfountz, Casey; Davis, Benjamin L; Hartley, Matthew; Imani, Hamed Pour; Slade, Zac; Kennefick, Daniel; Kennefick, Julia

    2015-01-01

    We present the MATLAB code Spirality, a novel method for measuring spiral arm pitch angles by fitting galaxy images to spiral templates of known pitch. Computation time is typically on the order of 2 minutes per galaxy, assuming at least 8 GB of working memory. We tested the code using 117 synthetic spiral images with known pitches, varying both the spiral properties and the input parameters. The code yielded correct results for all synthetic spirals with galaxy-like properties. We also compared the code's results to two-dimensional Fast Fourier Transform (2DFFT) measurements for the sample of nearby galaxies defined by DMS PPak. Spirality's error bars overlapped 2DFFT's error bars for 26 of the 30 galaxies. The two methods' agreement correlates strongly with galaxy radius in pixels and also with i-band magnitude, but not with redshift, a result that is consistent with at least some galaxies' spiral structure being fully formed by z=1.2, beyond which there are few galaxies in our sample. The Spirality code pa...

  9. NMR imaging and spectroscopy of the mammalian central nervous system after heavy ion radiation

    Energy Technology Data Exchange (ETDEWEB)

    Richards, T.

    1984-09-01

    NMR imaging, NMR spectroscopic, and histopathologic techniques were used to study the proton relaxation time and related biochemical changes in the central nervous system after helium beam in vivo irradiation of the rodent brain. The spectroscopic observations reported in this dissertation were made possible by development of methods for measuring the NMR parameters of the rodent brain in vivo and in vitro. The methods include (1) depth selective spectroscopy using an optimization of rf pulse energy based on a priori knowledge of N-acetyl aspartate and lipid spectra of the normal brain, (2) phase-encoded proton spectroscopy of the living rodent using a surface coil, and (3) dual aqueous and organic tissue extraction technique for spectroscopy. Radiation induced increases were observed in lipid and p-choline peaks of the proton spectrum, in vivo. Proton NMR spectroscopy measurements on brain extracts (aqueous and organic solvents) were made to observe chemical changes that could not be seen in vivo. Radiation-induced changes were observed in lactate, GABA, glutamate, and p-choline peak areas of the aqueous fraction spectra. In the organic fraction, decreases were observed in peak area ratios of the terminal-methyl peaks, the N-methyl groups of choline, and at a peak at 2.84 ppM (phosphatidyl ethanolamine and phosphatidyl serine resonances) relative to TMS. With histology and Evans blue injections, blood-brain barrier alternations were seen as early as 4 days after irradiation. 83 references, 53 figures.

  10. Characterization of liver lesions with mangafodipir trisodium-enhanced MR imaging: multicenter study comparing MR and dual-phase spiral CT

    NARCIS (Netherlands)

    M. Oudkerk (Matthijs); C.G. Torres; B. Song; M. Konig; J. Grimm; J. Fernandez-Cuadrado; B. op de Beeck; M. Marquardt; P. van Dijk (Pieter); J.C. de Groot (Jan Cees)

    2002-01-01

    textabstractPURPOSE: To evaluate whether mangafodipir trisodium (Mn-DPDP)-enhanced magnetic resonance (MR) imaging surpasses dual-phase spiral computed tomography (CT) in differentiating focal liver lesions. MATERIALS AND METHODS: One hundred forty-five patients who had or were sus

  11. Characterization of liver lesions with mangafodipir trisodium-enhanced MR imaging : Multicenter study comparing MR and dual-phase spiral CT

    NARCIS (Netherlands)

    Oudkerk, M; Torres, CG; Song, B; Konig, M; Fernandez-Cuadrado, J; de Beeck, BO; Marquardt, M; van Dijk, P.; de Groot, JC

    2002-01-01

    PURPOSE: To evaluate whether mangafodipir trisodium (Mn-DPDP)- enhanced magnetic resonance (MR) imaging surpasses dual-phase spiral computed tomography (CT) in differentiating focal liver lesions. MATERIALS AND METHODS: One hundred forty-five patients who had or were suspected of having focal liver

  12. Characterization of liver lesions with mangafodipir trisodium-enhanced MR imaging: multicenter study comparing MR and dual-phase spiral CT

    NARCIS (Netherlands)

    M. Oudkerk (Matthijs); C.G. Torres; B. Song; M. Konig; J. Grimm; J. Fernandez-Cuadrado; B. op de Beeck; M. Marquardt; P. van Dijk (Pieter); J.C. de Groot (Jan Cees)

    2002-01-01

    textabstractPURPOSE: To evaluate whether mangafodipir trisodium (Mn-DPDP)-enhanced magnetic resonance (MR) imaging surpasses dual-phase spiral computed tomography (CT) in differentiating focal liver lesions. MATERIALS AND METHODS: One hundred forty-five patients who had or were sus

  13. Characterization of liver lesions with mangafodipir trisodium-enhanced MR imaging : Multicenter study comparing MR and dual-phase spiral CT

    NARCIS (Netherlands)

    Oudkerk, M; Torres, CG; Song, B; Konig, M; Fernandez-Cuadrado, J; de Beeck, BO; Marquardt, M; van Dijk, P.; de Groot, JC

    2002-01-01

    PURPOSE: To evaluate whether mangafodipir trisodium (Mn-DPDP)- enhanced magnetic resonance (MR) imaging surpasses dual-phase spiral computed tomography (CT) in differentiating focal liver lesions. MATERIALS AND METHODS: One hundred forty-five patients who had or were suspected of having focal liver

  14. Jaws for a spiral-tooth whorl: CT images reveal novel adaptation and phylogeny in fossil Helicoprion.

    Science.gov (United States)

    Tapanila, Leif; Pruitt, Jesse; Pradel, Alan; Wilga, Cheryl D; Ramsay, Jason B; Schlader, Robert; Didier, Dominique A

    2013-04-23

    New CT scans of the spiral-tooth fossil, Helicoprion, resolve a longstanding mystery concerning the form and phylogeny of this ancient cartilaginous fish. We present the first three-dimensional images that show the tooth whorl occupying the entire mandibular arch, and which is supported along the midline of the lower jaw. Several characters of the upper jaw show that it articulated with the neurocranium in two places and that the hyomandibula was not part of the jaw suspension. These features identify Helicoprion as a member of the stem holocephalan group Euchondrocephali. Our reconstruction illustrates novel adaptations, such as lateral cartilage to buttress the tooth whorl, which accommodated the unusual trait of continuous addition and retention of teeth in a predatory chondrichthyan. Helicoprion exemplifies the climax of stem holocephalan diversification and body size in Late Palaeozoic seas, a role dominated today by sharks and rays.

  15. Spirality: A Noval Way to Measure Spiral Arm Pitch Angle

    Science.gov (United States)

    Shields, Douglas W.; Boe, Benjamin; Henderson, Casey L.; Hartley, Matthew; Davis, Benjamin L.; Pour Imani, Hamed; Kennefick, Daniel; Kennefick, Julia D.

    2015-01-01

    We present the MATLAB code Spirality, a novel method for measuring spiral arm pitch angles by fitting galaxy images to spiral templates of known pitch. For a given pitch angle template, the mean pixel value is found along each of typically 1000 spiral axes. The fitting function, which shows a local maximum at the best-fit pitch angle, is the variance of these means. Error bars are found by varying the inner radius of the measurement annulus and finding the standard deviation of the best-fit pitches. Computation time is typically on the order of 2 minutes per galaxy, assuming at least 8 GB of working memory. We tested the code using 128 synthetic spiral images of known pitch. These spirals varied in the number of spiral arms, pitch angle, degree of logarithmicity, radius, SNR, inclination angle, bar length, and bulge radius. A correct result is defined as a result that matches the true pitch within the error bars, with error bars no greater than ±7°. For the non-logarithmic spiral sample, the correct answer is similarly defined, with the mean pitch as function of radius in place of the true pitch. For all synthetic spirals, correct results were obtained so long as SNR > 0.25, the bar length was no more than 60% of the spiral's diameter (when the bar was included in the measurement), the input center of the spiral was no more than 6% of the spiral radius away from the true center, and the inclination angle was no more than 30°. The synthetic spirals were not deprojected prior to measurement. The code produced the correct result for all barred spirals when the measurement annulus was placed outside the bar. Additionally, we compared the code's results against 2DFFT results for 203 visually selected spiral galaxies in GOODS North and South. Among the entire sample, Spirality's error bars overlapped 2DFFT's error bars 64% of the time. For those galaxies in which Source code is available by email request from the primary author.

  16. Contrast investigation of multi-slice spiral CT perfusion imaging and pathological findings in VX2 soft-tissue tumor of rabbits

    Institute of Scientific and Technical Information of China (English)

    Jingfeng Zhang; Renfa Wang; Min Wang; Jing Zhang; Jinmei Sang

    2005-01-01

    Objective: To perform a contrast investigation of multi-slice spiral CT (MSCT) perfusion imaging and pathological findings in VX2 soft-tissue tumor of rabbits, and discuss the applicative value of multi-slice spiral CT perfusion imaging in soft-tissue tumors. Methods: 8 Newzealand white rabbits were implanted with 0.1 ml VX2 tumor tissue suspension in bilateral proximal thighs. 14 days and 21 days later, CT plain scan and perfusion scan were performed on these rabbits respectively, then the images were transmitted to AW4.0 workstation, the functional maps and perfusion parameters including blood flow (BF), blood volume (BV), mean transit time(MTT) and permeability surface (PS) were computed and analyzed. Subsequently, the rabbits were sacrificed, the tumors of which were taken out for pathological examination. The correlation between MSCT functional parametric images and pathological findings was analyzed.Results: All the values of BF, BV and PS of VX2 soft-tissue tumors were obviously higher while the MTT-values were lower than those of the normal muscular tissues significantly ( P < 0.001). Conclusion: Multi-slice spiral CT perfusion imaging is an accurate, convenient and relatively safe functional imaging technique, which can give a quantitative assessment to blood perfusion and angiogenesis of soft-tissue tumors.

  17. Local orbital angular momentum revealed by spiral phase plate imaging in transmission electron microscopy

    CERN Document Server

    Juchtmans, Roeland

    2015-01-01

    The orbital angular momentum (OAM) of light and matter waves is a parameter that is getting increasingly more attention over the past couple of years. Beams with a well defined OAM, the so-called vortex beams, are applied already in e.g. telecommunication, astrophysics, nanomanipulation and chiral measurements in optics and electron microscopy. Also the OAM of a wave induced by the interaction with a sample, shows great potential of interest. In all these experiments it is crucial to measure the exact (local) OAM content of the wave, whether it is an incoming vortex beam or an exit wave after interacting with a sample. In this work we investigate the use of spiral phase plates as an alternative to the programmable phase plates used in optics to measure OAM. We derive analytically how these can be used to study the local OAM components of any wave function. By means of numerical simulations we illustrate how the OAM of a pure vortex beam can be measured. We also look at a sum of misaligned vortex beams and sho...

  18. Investigating the Dissolution Performance of Amorphous Solid Dispersions Using Magnetic Resonance Imaging and Proton NMR.

    Science.gov (United States)

    Tres, Francesco; Coombes, Steven R; Phillips, Andrew R; Hughes, Leslie P; Wren, Stephen A C; Aylott, Jonathan W; Burley, Jonathan C

    2015-09-10

    We have investigated the dissolution performance of amorphous solid dispersions of poorly water-soluble bicalutamide in a Kollidon VA64 polymeric matrix as a function of the drug loading (5% vs. 30% bicalutamide). A combined suite of state-of-the-art analytical techniques were employed to obtain a clear picture of the drug release, including an integrated magnetic resonance imaging UV-Vis flow cell system and 1H-NMR. Off-line 1H-NMR was used for the first time to simultaneously measure the dissolution profiles and rates of both the drug and the polymer from a solid dispersion. MRI and 1H-NMR data showed that the 5% drug loading compact erodes linearly, and that bicalutamide and Kollidon VA64 are released at approximately the same rate from the molecular dispersion. For the 30% extrudate, data indicated a slower water ingress into the compact which corresponds to a slower dissolution rate of both bicalutamide and Kollidon VA64.

  19. Investigating the Dissolution Performance of Amorphous Solid Dispersions Using Magnetic Resonance Imaging and Proton NMR

    Directory of Open Access Journals (Sweden)

    Francesco Tres

    2015-09-01

    Full Text Available We have investigated the dissolution performance of amorphous solid dispersions of poorly water-soluble bicalutamide in a Kollidon VA64 polymeric matrix as a function of the drug loading (5% vs. 30% bicalutamide. A combined suite of state-of-the-art analytical techniques were employed to obtain a clear picture of the drug release, including an integrated magnetic resonance imaging UV-Vis flow cell system and 1H-NMR. Off-line 1H-NMR was used for the first time to simultaneously measure the dissolution profiles and rates of both the drug and the polymer from a solid dispersion. MRI and 1H-NMR data showed that the 5% drug loading compact erodes linearly, and that bicalutamide and Kollidon VA64 are released at approximately the same rate from the molecular dispersion. For the 30% extrudate, data indicated a slower water ingress into the compact which corresponds to a slower dissolution rate of both bicalutamide and Kollidon VA64.

  20. Biological effects and physical safety aspects of NMR imaging and in vivo spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Tenforde, T.S.; Budinger, T.F.

    1985-08-01

    An assessment is made of the biological effects and physical hazards of static and time-varying fields associated with the NMR devices that are being used for clinical imaging and in vivo spectroscopy. A summary is given of the current state of knowledge concerning the mechanisms of interaction and the bioeffects of these fields. Additional topics that are discussed include: (1) physical effects on pacemakers and metallic implants such as aneurysm clips, (2) human health studies related to the effects of exposure to nonionizing electromagnetic radiation, and (3) extant guidelines for limiting exposure of patients and medical personnel to the fields produced by NMR devices. On the basis of information available at the present time, it is concluded that the fields associated with the current generation of NMR devices do not pose a significant health risk in themselves. However, rigorous guidelines must be followed to avoid the physical interaction of these fields with metallic implants and medical electronic devices. 476 refs., 5 figs., 2 tabs.

  1. Spiral Computed Tomography Based Maxillary Sinus Imaging in Relation to Tooth Loss, Implant Placement and Potential Grafting Procedure

    Directory of Open Access Journals (Sweden)

    Reinhilde Jacobs

    2010-01-01

    Full Text Available Objectives: The purpose of the present study was to explore the maxillary sinus anatomy, its variations and volume in patients with a need for maxillary implant placement.Materials and Methods: Maxillary sinus data of 101 consecutive patients who underwent spiral computed tomography (CT scans for preoperative implant planning in the maxilla at the Department of Periodontology, University Hospital, Catholic University of Leuven, Leuven, Belgium were retrospectively evaluated. The alveolar bone height was measured on serial cross-sectional images between alveolar crest and sinus floor, parallel to the tooth axis. In order to describe the size of the maxillary sinus anteroposterior (AP and mediolateral (ML diameters of the sinus were measured.Results: The results indicated that the alveolar bone height was significantly higher in the premolar regions in comparison to the molar region (n = 46, P 4 mm mucosal thickening mostly at the level of the sinus floor. The present sample did not allow revealing any significant difference (P > 0.05 in maxillary sinus dimensions for partially dentate and edentulous subjects.Conclusions: Cross-sectional imaging can be used in order to obtain more accurate information on the morphology, variation, and the amount of maxillary bone adjacent to the maxillary sinus.

  2. Spiral computed tomography based maxillary sinus imaging in relation to tooth loss, implant placement and potential grafting procedure.

    Science.gov (United States)

    Shahbazian, Maryam; Xue, Dong; Hu, Yuqian; van Cleynenbreugel, Johan; Jacobs, Reinhilde

    2010-01-01

    The purpose of the present study was to explore the maxillary sinus anatomy, its variations and volume in patients with a need for maxillary implant placement. Maxillary sinus data of 101 consecutive patients who underwent spiral computed tomography (CT) scans for preoperative implant planning in the maxilla at the Department of Periodontology, University Hospital, Catholic University of Leuven, Leuven, Belgium were retrospectively evaluated. The alveolar bone height was measured on serial cross-sectional images between alveolar crest and sinus floor, parallel to the tooth axis. In order to describe the size of the maxillary sinus anteroposterior (AP) and mediolateral (ML) diameters of the sinus were measured. The results indicated that the alveolar bone height was significantly higher in the premolar regions in comparison to the molar region (n = 46, P maxillary sinuses were mostly located in the first premolar (49%) and second molar (84%) regions, respectively. Maxillary sinus septa were indentified in 47% of the maxillary antra. Almost 2/3 (66%) of the patients showed major (> 4 mm) mucosal thickening mostly at the level of the sinus floor. The present sample did not allow revealing any significant difference (P > 0.05) in maxillary sinus dimensions for partially dentate and edentulous subjects. Cross-sectional imaging can be used in order to obtain more accurate information on the morphology, variation, and the amount of maxillary bone adjacent to the maxillary sinus.

  3. Feasibility of slice width reduction for spiral cranial computed tomography using iterative image reconstruction

    Energy Technology Data Exchange (ETDEWEB)

    Haubenreisser, Holger; Fink, Christian; Nance, John W. [Institute of Clinical Radiology and Nuclear Medicine, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University (Germany); Sedlmair, Martin; Schmidt, Bernhard [Siemens Healthcare, Division CT, Forchheim (Germany); Schoenberg, Stefan O. [Institute of Clinical Radiology and Nuclear Medicine, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University (Germany); Henzler, Thomas, E-mail: thomas.henzler@medma.uni-heidelberg.de [Institute of Clinical Radiology and Nuclear Medicine, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University (Germany)

    2014-06-15

    Purpose: To prospectively compare image quality of cranial computed tomography (CCT) examinations with varying slice widths using traditional filtered back projection (FBP) versus sinogram-affirmed iterative image reconstruction (SAFIRE). Materials and methods: 29 consecutive patients (14 men, mean age: 72 ± 17 years) referred for a total of 40 CCT studies were prospectively included. Each CCT raw data set was reconstructed with FBP and SAFIRE at 5 slice widths (1–5 mm; 1 mm increments). Objective image quality was assessed in three predefined regions of the brain (white matter, thalamus, cerebellum) using identical regions of interest (ROIs). Subjective image quality was assessed by 2 experienced radiologists. Objective and subjective image quality parameters were statistically compared between FBP and SAFIRE reconstructions. Results: SAFIRE reconstructions resulted in mean noise reductions of 43.8% in the white matter, 45.6% in the thalamus and 42.0% in the cerebellum (p < 0.01) compared to FBP on non contrast-enhanced 1 mm slice width images. Corresponding mean noise reductions on 1 mm contrast-enhanced studies were 45.7%, 47.3%, and 45.0% in the white matter, thalamus, and cerebellum, respectively (p < 0.01). There was no significant difference in mean attenuation of any region or slice width between the two reconstruction methods (all p > 0.05). Subjective image quality of IR images was mostly rated higher than that of the FBP images. Conclusion: Compared to FBP, SAFIRE provides significant reductions in image noise while increasing subjective image in CCT, particularly when thinner slices are used. Therefore, SAFIRE may allow utilization of thinner slices in CCT, potentially reducing partial volume effects and improving diagnostic accuracy.

  4. Acquisition-weighted stack of spirals for fast high-resolution three-dimensional ultra-short echo time MR imaging.

    Science.gov (United States)

    Qian, Yongxian; Boada, Fernando E

    2008-07-01

    Ultra-short echo time (UTE) MRI requires both short excitation ( approximately 0.5 ms) and short acquisition delay (spirals (AWSOS), is proposed here to acquire high-resolution three-dimensional (3D) UTE images with short scan time ( approximately 72 s). The AWSOS sequence uses variable-duration slice encoding to minimize T(2) decay, separates slice thickness from in-plane resolution to reduce the number of slice encodings, and uses spiral trajectories to accelerate in-plane data collections. T(2)- and off-resonance induced slice widening and image blurring were calculated from 1.5 to 7 Tesla (T) through point spread function. Computer simulations were performed to optimize spiral interleaves and readout times. Phantom scans and in vivo experiments on human heads were implemented on a clinical 1.5T scanner (G(max) = 40 mT/m, S(max) = 150 T/m/s). Accounting for the limits on B(1) maximum, specific absorption rate (SAR), and the lowered amplitude of slab-select gradient, a sinc radiofrequency (RF) pulse of 0.8ms duration and 1.5 cycles was found to produce a flat slab profile. High in-plane resolution (0.86 mm) images were obtained for the human head using echo time (TE) = 0.608 ms and total shots = 720 (30 slice-encodings x 24 spirals). Compared with long-TE (10 ms) images, the ultrashort-TE AWSOS images provided clear visualization of short-T(2) tissues such as the nose cartilage, the eye optic nerve, and the brain meninges and parenchyma.

  5. Fast 3D Spatial EPR Imaging Using Spiral Magnetic Field Gradient

    OpenAIRE

    2007-01-01

    Electron paramagnetic resonance imaging (EPRI) provides direct detection and mapping of free radicals. The continuous wave (CW) EPRI technique, in particular, has been widely used in a variety of applications in the fields of biology and medicine due to its high sensitivity and applicability to a wide range of free radicals and paramagnetic species. However, the technique requires long image acquisition periods, and this limits its use for many in vivo applications where relatively rapid chan...

  6. Massive Star Formation Rates and Radial Distributions from Halpha Imaging of 84 Virgo Cluster and Isolated Spiral Galaxies

    CERN Document Server

    Koopmann, R A; Koopmann, Rebecca A.; Kenney, Jeffrey D. P.

    2002-01-01

    The massive star formation properties of 55 Virgo Cluster and 29 isolated S0-Scd spiral galaxies are compared via analyses of R and Halpha surface photometry and integrated fluxes as functions of Hubble type and central R light concentration. The total massive star formation rates in Virgo Cluster spirals have been reduced by factors up to 2.5 in the median compared to isolated spirals. The inner disk star formation rates of most Virgo Cluster spirals are similar or enhanced by factors up to 2.5 in the median, while outer disk star formation rates are reduced by factors up to 7.1 in the median. Thus the reduction in total star formation of Virgo Cluster spirals is caused primarily by truncation of the star-forming disks. The star formation morphologies of Virgo Cluster spirals compared to isolated spirals can be divided into four categories: normal (27%), anemic (6%), enhanced (15%), and truncated (52%). Several galaxies with truncated star-forming disks have anemic inner disks, but the majority have normal-e...

  7. Abdominal 4D flow MR imaging in a breath hold: combination of spiral sampling and dynamic compressed sensing for highly accelerated acquisition.

    Science.gov (United States)

    Dyvorne, Hadrien; Knight-Greenfield, Ashley; Jajamovich, Guido; Besa, Cecilia; Cui, Yong; Stalder, Aurélien; Markl, Michael; Taouli, Bachir

    2015-04-01

    To develop a highly accelerated phase-contrast cardiac-gated volume flow measurement (four-dimensional [4D] flow) magnetic resonance (MR) imaging technique based on spiral sampling and dynamic compressed sensing and to compare this technique with established phase-contrast imaging techniques for the quantification of blood flow in abdominal vessels. This single-center prospective study was compliant with HIPAA and approved by the institutional review board. Ten subjects (nine men, one woman; mean age, 51 years; age range, 30-70 years) were enrolled. Seven patients had liver disease. Written informed consent was obtained from all participants. Two 4D flow acquisitions were performed in each subject, one with use of Cartesian sampling with respiratory tracking and the other with use of spiral sampling and a breath hold. Cartesian two-dimensional (2D) cine phase-contrast images were also acquired in the portal vein. Two observers independently assessed vessel conspicuity on phase-contrast three-dimensional angiograms. Quantitative flow parameters were measured by two independent observers in major abdominal vessels. Intertechnique concordance was quantified by using Bland-Altman and logistic regression analyses. There was moderate to substantial agreement in vessel conspicuity between 4D flow acquisitions in arteries and veins (κ = 0.71 and 0.61, respectively, for observer 1; κ = 0.71 and 0.44 for observer 2), whereas more artifacts were observed with spiral 4D flow (κ = 0.30 and 0.20). Quantitative measurements in abdominal vessels showed good equivalence between spiral and Cartesian 4D flow techniques (lower bound of the 95% confidence interval: 63%, 77%, 60%, and 64% for flow, area, average velocity, and peak velocity, respectively). For portal venous flow, spiral 4D flow was in better agreement with 2D cine phase-contrast flow (95% limits of agreement: -8.8 and 9.3 mL/sec, respectively) than was Cartesian 4D flow (95% limits of agreement: -10.6 and 14.6 m

  8. Imaging and spectroscopic observations of a strange elliptical bubble in the northern arm of the spiral galaxy NGC 6946

    CERN Document Server

    Efremov, Yuri N

    2016-01-01

    NGC 6946, known as the Fireworks galaxy because of its high supernova rate and high star formation, is embedded in a very extended HI halo. Its northern spiral arm is well detached from the galactic main body. We found that this arm contains a large (~300 pc in size) Red Ellipse, named according to a strong contamination of the H-alpha emission line on its optical images. The ellipse is accompanied by a short parallel arc and a few others still smaller and less regular; a bright star cluster is seen inside these features. The complicated combination of arcs seems to be unique, it is only a bit similar to some SNRs. However, the long-slit spectral data obtained with the Russian 6-m telescope did not confirm the origin of the nebula as a result of a single SN outburst. The emission-line spectrum corresponds to the photoionization by young hot stars with a small contribution of shock ionization. The most likely explanation of the Red Ellipse is a superbbuble created by a collective feedback of massive stars in t...

  9. Imaging and spectroscopic observations of a strange elliptical bubble in the northern arm of the spiral galaxy NGC 6946

    Science.gov (United States)

    Efremov, Yuri N.; Moiseev, Alexei V.

    2016-09-01

    NGC 6946, known as the Fireworks galaxy because of its high supernova rate and high star formation, is embedded in a very extended H I halo. Its northern spiral arm is well detached from the galactic main body. We found that this arm contains a large (˜300 pc in size) Red Ellipse, named according to a strong contamination of the Hα emission line on its optical images. The ellipse is accompanied by a short parallel arc and a few others still smaller and less regular; a bright star cluster is seen inside these features. The complicated combination of arcs seems to be unique; it is only a bit similar to some SNRs. However, the long-slit spectral data obtained with the Russian 6-m telescope did not confirm the origin of the nebula as a result of a single SN outburst. The emission-line spectrum corresponds to the photoionization by young hot stars with a small contribution of shock ionization. The most likely explanation of the Red Ellipse is a superbubble created by a collective feedback of massive stars in the star cluster located in the NE side of the Red Ellipse. However, the very regular elliptical shape of the nebulae seems strange.

  10. 3D spiral CT imaging of bone anomalies in a case of diastematomyelia

    Energy Technology Data Exchange (ETDEWEB)

    Skalej, Martin [Department of Neuroradiology, University of Tuebingen, Hoppe-Seyler Str. 3, 72076 Tuebingen (Germany); Duffner, Frank [Department of Neurosurgery, University of Tuebingen, Tuebingen (Germany); Stefanou, Alexander [Department of Neuroradiology, University of Tuebingen, Hoppe-Seyler Str. 3, 72076 Tuebingen (Germany); Petersen, Dirk [Department of Neuroradiology, University of Tuebingen, Hoppe-Seyler Str. 3, 72076 Tuebingen (Germany)

    1999-03-01

    The case of a 48-year-old woman, suffering from a diastematomyelia, is presented. This case and the diagnostic findings are used to demonstrate the demands on imaging methods with respect to a new classification of split cord malformations (SCMs) recently published. Although MRI is the method of choice for imaging of the spinal cord generally, only X-ray methods and especially conventional computer tomography provide the information necessary for correct classification of SCMs. Additional 3D-reconstructions from suitable CT-data are helpful in visualizing complex anomalies of bony structures found in most cases of SCM.

  11. The spiral

    DEFF Research Database (Denmark)

    Bibace, Roger; Kharlamov, Nikita

    2013-01-01

    At the core of Heinz Werner’s concept of development is what he called “the genetic principle of spirality:” over the course of ontogenetic development, lower levels, processes, and functions do not disappear, and can even resurface again under specific conditions, normal and pathological. Werner...

  12. Flexible proton 3D MR spectroscopic imaging of the prostate with low-power adiabatic pulses for volume selection and spiral readout.

    Science.gov (United States)

    Steinseifer, Isabell K; Philips, Bart W J; Gagoski, Borjan; Weiland, Elisabeth; Scheenen, Tom W J; Heerschap, Arend

    2017-03-01

    Cartesian k-space sampling in three-dimensional magnetic resonance spectroscopic imaging (MRSI) of the prostate limits the selection of voxel size and acquisition time. Therefore, large prostates are often scanned at reduced spatial resolutions to stay within clinically acceptable measurement times. Here we present a semilocalized adiabatic selective refocusing (sLASER) sequence with gradient-modulated offset-independent adiabatic (GOIA) refocusing pulses and spiral k-space acquisition (GOIA-sLASER-Spiral) for fast prostate MRSI with enhanced resolution and extended matrix sizes. MR was performed at 3 tesla with an endorectal receive coil. GOIA-sLASER-Spiral at an echo time (TE) of 90 ms was compared to a point-resolved spectroscopy sequence (PRESS) with weighted, elliptical phase encoding at an TE of 145 ms using simulations and measurements of phantoms and patients (n = 9). GOIA-sLASER-Spiral acquisition allows prostate MR spectra to be obtained in ∼5 min with a quality comparable to those acquired with a common Cartesian PRESS protocol in ∼9 min, or at an enhanced spatial resolution showing more precise tissue allocation of metabolites. Extended field of views (FOVs) and matrix sizes for large prostates are possible without compromising spatial resolution or measurement time. The flexibility of spiral sampling enables prostate MRSI with a wide range of resolutions and FOVs without undesirable increases in acquisition times, as in Cartesian encoding. This approach is suitable for routine clinical exams of prostate metabolites. Magn Reson Med 77:928-935, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

  13. 3D GABA imaging with real-time motion correction, shim update and reacquisition of adiabatic spiral MRSI.

    Science.gov (United States)

    Bogner, Wolfgang; Gagoski, Borjan; Hess, Aaron T; Bhat, Himanshu; Tisdall, M Dylan; van der Kouwe, Andre J W; Strasser, Bernhard; Marjańska, Małgorzata; Trattnig, Siegfried; Grant, Ellen; Rosen, Bruce; Andronesi, Ovidiu C

    2014-12-01

    Gamma-aminobutyric acid (GABA) and glutamate (Glu) are the major neurotransmitters in the brain. They are crucial for the functioning of healthy brain and their alteration is a major mechanism in the pathophysiology of many neuro-psychiatric disorders. Magnetic resonance spectroscopy (MRS) is the only way to measure GABA and Glu non-invasively in vivo. GABA detection is particularly challenging and requires special MRS techniques. The most popular is MEscher-GArwood (MEGA) difference editing with single-voxel Point RESolved Spectroscopy (PRESS) localization. This technique has three major limitations: a) MEGA editing is a subtraction technique, hence is very sensitive to scanner instabilities and motion artifacts. b) PRESS is prone to localization errors at high fields (≥3T) that compromise accurate quantification. c) Single-voxel spectroscopy can (similar to a biopsy) only probe steady GABA and Glu levels in a single location at a time. To mitigate these problems, we implemented a 3D MEGA-editing MRS imaging sequence with the following three features: a) Real-time motion correction, dynamic shim updates, and selective reacquisition to eliminate subtraction artifacts due to scanner instabilities and subject motion. b) Localization by Adiabatic SElective Refocusing (LASER) to improve the localization accuracy and signal-to-noise ratio. c) K-space encoding via a weighted stack of spirals provides 3D metabolic mapping with flexible scan times. Simulations, phantom and in vivo experiments prove that our MEGA-LASER sequence enables 3D mapping of GABA+ and Glx (Glutamate+Gluatmine), by providing 1.66 times larger signal for the 3.02ppm multiplet of GABA+ compared to MEGA-PRESS, leading to clinically feasible scan times for 3D brain imaging. Hence, our sequence allows accurate and robust 3D-mapping of brain GABA+ and Glx levels to be performed at clinical 3T MR scanners for use in neuroscience and clinical applications.

  14. Computer-aided diagnosis: a 3D segmentation method for lung nodules in CT images by use of a spiral-scanning technique

    Science.gov (United States)

    Wang, Jiahui; Engelmann, Roger; Li, Qiang

    2008-03-01

    Lung nodule segmentation in computed tomography (CT) plays an important role in computer-aided detection, diagnosis, and quantification systems for lung cancer. In this study, we developed a simple but accurate nodule segmentation method in three-dimensional (3D) CT. First, a volume of interest (VOI) was determined at the location of a nodule. We then transformed the VOI into a two-dimensional (2D) image by use of a "spiral-scanning" technique, in which a radial line originating from the center of the VOI spirally scanned the VOI. The voxels scanned by the radial line were arranged sequentially to form a transformed 2D image. Because the surface of a nodule in 3D image became a curve in the transformed 2D image, the spiral-scanning technique considerably simplified our segmentation method and enabled us to obtain accurate segmentation results. We employed a dynamic programming technique to delineate the "optimal" outline of a nodule in the 2D image, which was transformed back into the 3D image space to provide the interior of the nodule. The proposed segmentation method was trained on the first and was tested on the second Lung Image Database Consortium (LIDC) datasets. An overlap between nodule regions provided by computer and by the radiologists was employed as a performance metric. The experimental results on the LIDC database demonstrated that our segmentation method provided relatively robust and accurate segmentation results with mean overlap values of 66% and 64% for the nodules in the first and second LIDC datasets, respectively, and would be useful for the quantification, detection, and diagnosis of lung cancer.

  15. Similarity between the Spiral Arms of Galaxy M51 Image and the Interface Curve of Yin-Yang Balance in the Ancient Tai-Chi Diagram

    Institute of Scientific and Technical Information of China (English)

    Sui Lin

    2009-01-01

    The particle paths of the Lagrangian flow field between two cylinders simulate well the spiral arms of Galaxy M51 image [1] and the interface curve of the Yin-Yang balance in the ancient Tai-Chi diagram [2]. The particle paths of the Lagrangian flow field involve four parameters. The normalization of the system of equations signifi-cantly simplifies the formulation of the flow process and reduces the original four parameters to only one pa-rameter. Furthermore it provides the similarity between the formulation of the spiral arms of Galaxy M51 and that of the interface curve of the Yin-Yang balance in the ancient Tal-Chi diagram.

  16. Spiral inflation

    Directory of Open Access Journals (Sweden)

    Gabriela Barenboim

    2015-02-01

    Full Text Available We propose a novel scenario of primordial inflation in which the inflaton goes through a spiral motion starting from around the top of a symmetry breaking potential. We show that, even though inflation takes place for a field value much smaller than Planck scale, it is possible to obtain relatively large tensor-to-scalar ratio (r∼0.1 without fine tuning. The inflationary observables perfectly match Planck data.

  17. Right Ventricular Strain, Torsion, and Dyssynchrony in Healthy Subjects using 3D Spiral Cine DENSE Magnetic Resonance Imaging.

    Science.gov (United States)

    Suever, Jonathan; Wehner, Gregory; Jing, Linyuan; Powell, David; Hamlet, Sean; Grabau, Jonathan; Mojsejenko, Dimitri; Andres, Kristin; Haggerty, Christopher; Fornwalt, Brandon

    2016-12-29

    Mechanics of the left ventricle (LV) are important indicators of cardiac function. The role of right ventricular (RV) mechanics is largely unknown due to the technical limitations of imaging its thin wall and complex geometry and motion. By combining 3D Displacement Encoding with Stimulated Echoes (DENSE) with a post-processing pipeline that includes a local coordinate system, it is possible to quantify RV strain, torsion, and synchrony. In this study, we sought to characterize RV mechanics in 50 healthy individuals and compare these values to their LV counterparts. For each cardiac frame, 3D displacements were fit to continuous and differentiable radial basis functions, allowing for the computation of the 3D Cartesian Lagrangian strain tensor at any myocardial point. The geometry of the RV was extracted via a surface fit to manually delineated endocardial contours. Throughout the RV, a local coordinate system was used to transform from a Cartesian strain tensor to a polar strain tensor. It was then possible to compute peak RV torsion as well as peak longitudinal and circumferential strain. A comparable analysis was performed for the LV. Dyssynchrony was computed from the standard deviation of regional activation times. Global circumferential strain was comparable between the RV and LV (-18.0% for both) while longitudinal strain was greater in the RV (-18.1% vs. -15.7%). RV torsion was comparable to LV torsion (6.2 vs. 7.1 degrees, respectively). Regional activation times indicated that the RV contracted later but more synchronously than the LV. 3D spiral cine DENSE combined with a post-processing pipeline that includes a local coordinate system can resolve both the complex geometry and 3D motion of the RV.

  18. NMR imaging and hydrodynamic analysis of neutrally buoyant non-Newtonian slurry flows

    Science.gov (United States)

    Bouillard, J. X.; Sinton, S. W.

    The flow of solids loaded suspension in cylindrical pipes has been the object of intense experimental and theoretical investigations in recent years. These types of flows are of great interest in chemical engineering because of their important use in many industrial manufacturing processes. Such flows are for example encountered in the manufacture of solid-rocket propellants, advanced ceramics, reinforced polymer composites, in heterogeneous catalytic reactors, and in the pipeline transport of liquid-solids suspensions. In most cases, the suspension microstructure and the degree of solids dispersion greatly affect the final performance of the manufactured product. For example, solid propellant pellets need to be extremely-well dispersed in gel matrices for use as rocket engine solid fuels. The homogeneity of pellet dispersion is critical to allow good uniformity of the burn rate, which in turn affects the final mechanical performance of the engine. Today's manufacturing of such fuels uses continuous flow processes rather than batch processes. Unfortunately, the hydrodynamics of such flow processes is poorly understood and is difficult to assess because it requires the simultaneous measurements of liquid/solids phase velocities and volume fractions. Due to the recent development in pulsed Fourier Transform NMR imaging, NMR imaging is now becoming a powerful technique for the non intrusive investigation of multi-phase flows. This paper reports and exposes a state-of-the-art experimental and theoretical methodology that can be used to study such flows. The hydrodynamic model developed for this study is a two-phase flow shear thinning model with standard constitutive fluid/solids interphase drag and solids compaction stresses. this model shows good agreement with experimental data and the limitations of this model are discussed.

  19. Compact NMR

    Energy Technology Data Exchange (ETDEWEB)

    Bluemich, Bernhard; Haber-Pohlmeier, Sabina; Zia, Wasif [RWTH Aachen Univ. (Germany). Inst. fuer Technische und Makromolekulare Chemie (ITMC)

    2014-06-01

    Nuclear Magnetic Resonance (NMR) spectroscopy is the most popular method for chemists to analyze molecular structures, while Magnetic Resonance Imaging (MRI) is a non-invasive diagnostic tool for medical doctors that provides high-contrast images of biological tissue. In both applications, the sample (or patient) is positioned inside a large, superconducting magnet to magnetize the atomic nuclei. Interrogating radio-frequency pulses result in frequency spectra that provide the chemist with molecular information, the medical doctor with anatomic images, and materials scientist with NMR relaxation parameters. Recent advances in magnet technology have led to a variety of small permanent magnets to allow compact and low-cost instruments. The goal of this book is to provide an introduction to the practical use of compact NMR at a level nearly as basic as the operation of a smart phone.

  20. Entoptic perceptions of spiral waves and rare inward spirals.

    Science.gov (United States)

    Pearce, Ida

    2015-06-01

    This report concerns Entoptic Rotating Spiral Waves as observed and documented by the author over a period of 46 years (1962-2008). The manifestations of these state-dependent, elusive rotating spiral entities were brief, emerging only during sleep-to-waking arousal epochs (in limbo). The images were seen only with closed lids in favorable ambient lighting-here, termed the umbral view. The clusters of rotating spiral entities emerge briefly to conscious view; their angular subtenses are estimated to be between 1° and 4°, and the rotations at ten-turns per second. Epochs of these activities commonly continued for about 20 s, with longevity of each visible entity up to 4 s. 90% of all observed entities were circular and outwardly levorotary; 5% were elliptical, appearing only as horizontal (prolate) entities. Overlapping units were rare, and were chiefly elliptical. Observations of twin spirals were also rare, seen in counter rotations, each twin inwardly rotating.

  1. Digital volume tomography (DVT) and multislice spiral CT (MSCT). An objective examination of dose and image quality; Digitale Volumentomografie (DVT) und Mehrschicht-Spiral-CT (MSCT). Eine objektive Untersuchung von Dosis und Bildqualitaet

    Energy Technology Data Exchange (ETDEWEB)

    Kyriakou, Y.; Kolditz, D.; Langner, O.; Krause, J.; Kalender, W. [Erlangen-Nuernberg Univ. (Germany). Inst. fuer Medizinische Physik

    2011-02-15

    Purpose: In the last five years digital volume tomographs (DVT) have found their way into the diagnostic imaging of the facial skull. In this study both the image quality and dose of DVT and multislice spiral CT (MSCT) in this field of application were investigated using established physical methods for CT. Materials and Methods: Measurements on DVT scanners of various manufacturers and on a modern MSCT scanner were performed. The investigation was based on equivalent dose levels for both modalities (CT dose index, CTDI). For this purpose, the dose was measured with an ionization chamber in a cylindrical PMMA phantom. For the evaluation of image quality, the spatial resolution, contrast and noise were investigated with phantoms established for CT. Results: MSCT exhibited spatial resolution values of 1.0 to 1.6 lp/mm, while DVT provided resolution between 0.6 and 1.0 lp/mm only. Thus, MSCT offered similar or better resolution at an equivalent dose. For soft tissue resolution, DVT showed significant image artifacts. MSCT yielded higher homogeneity and no significant artifacts, and the contrast steps of the phantom were more verifiable. The different DVT devices, from image intensifiers to modern flat-detector (FD) devices, showed significant differences in favor of the FD devices. Conclusion: For medium and high contrast applications (teeth/bones), DVT scanners can be an alternative to MSCT at comparable radiation exposure. However, MSCT offers advantages in terms of constantly good and controlled image quality with significantly more flexible scan parameters at a constant or lower dose and should therefore be given preference. (orig.)

  2. Spiralling upward.

    Science.gov (United States)

    Schulgasser, Kalman; Witztum, Allan

    2004-09-21

    Thin vertical leaves often manifest twist. Perhaps the most prominent example of this is in Typha sp., but such twist is also apparent in Narcissus, Pancratium and many other genera. Such a blade is often referred to as a "spiral leaf". We will indicate the mechanical advantage afforded to the leaf by this arrangement, i.e. that it permits the leaf to achieve a greater height without losing stability, that is bending over due to its own weight. We quantify this gain and show how by a simple experiment it can be shown that the advantage is indeed utilized in nature. Typha domingensis is offered as an example.

  3. The spiral

    DEFF Research Database (Denmark)

    Bibace, Roger; Kharlamov, Nikita

    2013-01-01

    ’s work with Bernard Kaplan on symbol formation is a primer on this idea. This paper examines the idea of spirality and develops the notion of dynamic coexistence that can clarify the issue of directionality of development; that is, what is the general trajectory or ground plan that development assumes....... Directionality is discussed in terms of the organism-in-environment unfolding over time as the unit of developmental analysis. Thinking on this issue has proceeded from the nature–nurture debates, to recognition of the interaction of external and internal processes, to transactions between the organism...

  4. NMR imaging of fluid exchange between macropores and matrix in eogenetic karst

    Science.gov (United States)

    Florea, L.J.; Cunningham, K.J.; Altobelli, S.

    2009-01-01

    Sequential time-step images acquired using nuclear magnetic resonance (NMR) show the displacement of deuterated water (D2O) by fresh water within two limestone samples characterized by a porous and permeable limestone matrix of peloids and ooids. These samples were selected because they have a macropore system representative of some parts of the eogenetic karst limestone of the Biscayne Aquifer in southeastern Florida. The macroporosity, created by the trace fossil Ophiomorpha, is principally well connected and of centimeter scale. These macropores occur in broadly continuous stratiform zones that create preferential flow layers within the hydrogeologic units of the Biscayne. This arrangement of porosity is important because in coastal areas, it could produce a preferential pathway for salt water intrusion. Two experiments were conducted in which samples saturated with D2O were placed in acrylic chambers filled with fresh water and examined with NMR. Results reveal a substantial flux of fresh water into the matrix porosity with a simultaneous loss of D 2O. Specifically, we measured rates upward of 0.001 mL/h/g of sample in static conditions, and perhaps as great as 0.07 mL/h/g of sample when fresh water continuously flows past a sample at velocities less than those found within stressed areas of the Biscayne. These experiments illustrate how fresh water and D2O, with different chemical properties, migrate within one type of matrix porosity found in the Biscayne. Furthermore, these experiments are a comparative exercise in the displacement of sea water by fresh water in the matrix of a coastal, karst aquifer since D2O has a greater density than fresh water. ?? 2008 National Ground Water Association.

  5. Single-Shot Magnetic Resonance Imaging of a Moving Object Based on the High-Speed Spiral-Scan Echo Planner Technique at 4.7 T

    Institute of Scientific and Technical Information of China (English)

    卢广; 刘买利; 李丽云; 叶朝辉

    2002-01-01

    The single-shot spiral magnetic resonance imaging (MRI) technique was implemented and optimized on a Bruker Biospec47/30 scanner. The technique includes the pulse sequence for generation and detection of the k-space MRI signal (free induction decay (FID)), and PC-based programs for the data grid and image reconstruction.The temporal resolution is 70ms (14 images per second), which consists of a data acquisition time as short as 13.7 ms, a spin-echo time of 13.6 ms and a magnetization recovery time of 43 ms. This makes it possible to take real-time images of moving objects. The technique is demonstrated using a pendulum (tube) filled with water.

  6. Quantitative analysis of spirality in elliptical galaxies

    CERN Document Server

    Dojcsak, Levente

    2013-01-01

    We use an automated galaxy morphology analysis method to quantitatively measure the spirality of galaxies classified manually as elliptical. The data set used for the analysis consists of 60,518 galaxy images with redshift obtained by the Sloan Digital Sky Survey (SDSS) and classified manually by Galaxy Zoo, as well as the RC3 and NA10 catalogues. We measure the spirality of the galaxies by using the Ganalyzer method, which transforms the galaxy image to its radial intensity plot to detect galaxy spirality that is in many cases difficult to notice by manual observation of the raw galaxy image. Experimental results using manually classified elliptical and S0 galaxies with redshift <0.3 suggest that galaxies classified manually as elliptical and S0 exhibit a nonzero signal for the spirality. These results suggest that the human eye observing the raw galaxy image might not always be the most effective way of detecting spirality and curves in the arms of galaxies.

  7. Quantum spirals

    CERN Document Server

    Yoshida, Z

    2016-01-01

    Quantum systems often exhibit fundamental incapability to entertain vortex. The Meissner effect, a complete expulsion of the magnetic field (the electromagnetic vorticity), for instance, is taken to be the defining attribute of the superconducting state. Superfluidity is another, close-parallel example; fluid vorticity can reside only on topological defects with a limited (quantized) amount. Recent developments in the Bose-Einstein condensates produced by particle traps further emphasize this characteristic. We show that the challenge of imparting vorticity to a quantum fluid can be met through a nonlinear mechanism operating in a hot fluid corresponding to a thermally modified Pauli-Schroedinger spinor field. In a simple field-free model, we show that the thermal effect, represented by a nonlinear, non-Hermitian Hamiltonian, in conjunction with spin vorticity, leads to new interesting quantum states; a spiral solution is explicitly worked out.

  8. Spiral tectonics

    Science.gov (United States)

    Hassan Asadiyan, Mohammad

    2014-05-01

    Spiral Tectonics (ST) is a new window to global tectonics introduced as alternative model for Plate Tectonics (PT). ST based upon Dahw(rolling) and Tahw(spreading) dynamics. Analogues to electric and magnetic components in the electromagnetic theory we could consider Dahw and Tahw as components of geodynamics, when one component increases the other decreases and vice versa. They are changed to each other during geological history. D-component represents continental crust and T-component represents oceanic crust. D and T are two arm of spiral-cell. T-arm 180 degree lags behind D-arm so named Retard-arm with respect to D or Forward-arm. It seems primary cell injected several billions years ago from Earth's center therefore the Earth's core was built up first then mantel and finally the crust was build up. Crust building initiate from Arabia (Mecca). As the universe extended gravitation wave swirled the earth fractaly along cycloid path from big to small scale. In global scale (order-0) ST collect continents in one side and abandoned Pacific Ocean in the other side. Recent researches also show two mantels upwelling in opposite side of the Earth: one under Africa (tectonic pose) and the other under Pacific Ocean (tectonic tail). In higher order (order-1) ST build up Africa in one side and S.America in the other side therefore left Atlantic Ocean meandered in between. In order-n e.g. Khoor Musa and Bandar-Deylam bay are seen meandered easterly in the Iranian part but Khoor Abdullah and Kuwait bay meandered westerly in the Arabian part, they are distributed symmetrically with respect to axis of Persian Gulf(PG), these two are fractal components of easterly Caspian-wing and westerly Black Sea-wing which split up from Anatoly. Caspian Sea and Black Sea make two legs of Y-like structure, this shape completely fitted with GPS-velocity map which start from PG and split up in the Catastrophic Point(Anatoly). We could consider PG as remnants of Ancient Ocean which spent up

  9. Scale heights of 84 northern spiral galaxies

    Institute of Scientific and Technical Information of China (English)

    马骏; 彭秋和

    1997-01-01

    Using the method proposed by Peng (1988) on the basis of density waves theory and the solution of three-dimensional Poisson s equation for a logarithmic disturbance of density,and analyzing the spiral patterns,the scale heights of 84 northern spiral galaxies,whose images are taken from the Digitized Sky Survey at Xinglong Observational Station of Beijing Observatory,are measured.The spiral arms of all these galaxies have been fitted on their photographs with some logarithmic spiral curves for getting their correct inclinations.

  10. Forming Spirals From Shadows

    Science.gov (United States)

    Kohler, Susanna

    2016-07-01

    What causes the large-scale spiral structures found in some protoplanetary disks? Most models assume theyre created by newly-forming planets, but a new study suggests that planets might have nothing to do with it.Perturbations from Planets?In some transition disks protoplanetary disks with gaps in their inner regions weve directly imaged large-scale spiral arms. Many theories currently attribute the formation of these structures to young planets: either the direct perturbations of a planet embedded in the disk cause the spirals, or theyre indirectly caused by the orbit of a planetary body outside of the arms.Another example of spiral arms detected in a protoplanetary disk, MWC 758. [NASA/ESA/ESO/M. Benisty et al.]But what if you could get spirals without any planets? A team of scientists led by Matas Montesinos (University of Chile) have recently published a study in which they examine what happens to a shadowed protoplanetary disk.Casting Shadows with WarpsIn the teams setup, they envision a protoplanetary disk that is warped: the inner region is slightly tilted relative to the outer region. As the central star casts light out over its protoplanetary disk, this disk warping would cause some regions of the disk to be shaded in a way that isnt axially symmetric with potentially interesting implications.Montesinos and collaborators ran 2D hydrodynamics simulations to determine what happens to the motion of particles within the disk when they pass in and out of the shadowed regions. Since the shadowed regions are significantly colder than the illuminated disk, the pressure in these regions is much lower. Particles are therefore accelerated and decelerated as they pass through these regions, and the lack of axial symmetry causes spiral density waves to form in the disk as a result.Initial profile for the stellar heating rate per unit area for one of the authors simulations. The regions shadowed as a result of the disk warp subtend 0.5 radians each (shown on the left

  11. HUBBLE SPACE TELESCOPE AND HI IMAGING OF STRONG RAM PRESSURE STRIPPING IN THE COMA SPIRAL NGC 4921: DENSE CLOUD DECOUPLING AND EVIDENCE FOR MAGNETIC BINDING IN THE ISM

    Energy Technology Data Exchange (ETDEWEB)

    Kenney, Jeffrey D. P.; Abramson, Anne [Yale University Astronomy Department, P.O. Box 208101, New Haven, CT 06520-8101 (United States); Bravo-Alfaro, Hector, E-mail: jeff.kenney@yale.edu [Institut d’Astrophysique de Paris, CNRS/UPMC, 98bis, Boulevard Arago F-75014, Paris (France)

    2015-08-15

    Remarkable dust extinction features in the deep Hubble Space Telescope (HST) V and I images of the face-on Coma cluster spiral galaxy NGC 4921 show in unprecedented ways how ram pressure strips the ISM from the disk of a spiral galaxy. New VLA HI maps show a truncated and highly asymmetric HI disk with a compressed HI distribution in the NW, providing evidence for ram pressure acting from the NW. Where the HI distribution is truncated in the NW region, HST images show a well-defined, continuous front of dust that extends over 90° and 20 kpc. This dust front separates the dusty from dust-free regions of the galaxy, and we interpret it as galaxy ISM swept up near the leading side of the ICM–ISM interaction. We identify and characterize 100 pc–1 kpc scale substructure within this dust front caused by ram pressure, including head–tail filaments, C-shaped filaments, and long smooth dust fronts. The morphology of these features strongly suggests that dense gas clouds partially decouple from surrounding lower density gas during stripping, but decoupling is inhibited, possibly by magnetic fields that link and bind distant parts of the ISM.

  12. An advanced phantom study assessing the feasibility of neuronal current imaging by ultra-low-field NMR

    Science.gov (United States)

    Körber, Rainer; Nieminen, Jaakko O.; Höfner, Nora; Jazbinšek, Vojko; Scheer, Hans-Jürgen; Kim, Kiwoong; Burghoff, Martin

    2013-12-01

    In ultra-low-field (ULF) NMR/MRI, a common scheme is to magnetize the sample by a polarizing field of up to hundreds of mT, after which the NMR signal, precessing in a field on the order of several μT, is detected with superconducting quantum interference devices (SQUIDs). In our ULF-NMR system, we polarize with up to 50 mT and deploy a single-stage DC-SQUID current sensor with an integrated input coil which is connected to a wire-wound Nb gradiometer. We developed this system (white noise 0.50 fT/√{Hz}) for assessing the feasibility of imaging neuronal currents by detecting their effect on the ULF-NMR signal. Magnetoencephalography investigations of evoked brain activity showed neuronal dipole moments below 50 nAm. With our instrumentation, we have studied two different approaches for neuronal current imaging. In the so-called DC effect, long-lived neuronal activity shifts the Larmor frequency of the surrounding protons. An alternative strategy is to exploit fast neuronal activity as a tipping pulse. This so-called AC effect requires the proton Larmor frequency to match the frequency of the neuronal activity, which ranges from near-DC to ∼kHz. We emulated neuronal activity by means of a single dipolar source in a physical phantom, consisting of a hollow sphere filled with an aqueous solution of CuSO4 and NaCl. In these phantom studies, with physiologically relevant dipole depths, we determined resolution limits for our set-up for the AC and the DC effect of ∼10 μAm and ∼50 nAm, respectively. Hence, the DC effect appears to be detectable in vivo by current ULF-NMR technology.

  13. Investigation on the optical scan condition for imaging of multi-slice spiral CT liver perfusion in rats

    Institute of Scientific and Technical Information of China (English)

    BAI Rong-jie; WANG Jin-e; JIANG Hui-jie; HAO Xue-jia; DONG Xu-peng; HUANG Ya-hua; WEI Lai

    2013-01-01

    contrast agent was 19% or 38%,no pseudo-color map was created.The viscosity increased when the concentration of the contrast agent was 76%; so it is difficult to inject the contrast agent at such a high concentration.Also no pseudo-color map was generated when the injection time was short (1,2-3,and 4-5 seconds)or the injection rate was low (0.3 mi/s).The best perfusion images and perfusion parameters were obtained during 50 seconds scanning.Each rat was given an injection of 57% diatrizoate at 0.5 mi/s via the tail vein using a high-pressure syringe for 6 seconds.The perfusion parameters included hepatic blood flow (HBF),hepatic blood volume (HBV),mean transit time (MTT) of the contrast agent,capillary permeability-surface area product (PS),hepatic arterial index (HAI),hepatic artery perfusion (HAP),and hepatic portal perfusion (HPP).All these parameters reflected the perfusion status of liver parenchyma in normal rats,Three phases of enhancement were modified according to the time-density curves (TDCs) of the perfusion imaging:hepatic arterial phase (7 seconds),hepatic portal venous phase (15 seconds),and a delayed phase (23-31 seconds).On examination by microscopy,the liver tissues were pathologically normal.Conclusions The appropriate protocol with multi-slice spiral CT liver perfusion reflected normal liver hemodynamics in rats.This study laid a solid foundation for further investigation of the physiological characteristics of liver cancer in a rat model,and was an important supplement to and reference for conventional contrast-enhanced CT scans.

  14. Spiral Perfusion Imaging With Consecutive Echoes (SPICE™) for the Simultaneous Mapping of DSC- and DCE-MRI Parameters in Brain Tumor Patients: Theory and Initial Feasibility

    Science.gov (United States)

    Paulson, Eric S.; Prah, Douglas E.; Schmainda, Kathleen M.

    2017-01-01

    Dynamic contrast-enhanced (DCE) and dynamic susceptibility contrast (DSC) magnetic resonance imaging (MRI) are the perfusion imaging techniques most frequently used to probe the angiogenic character of brain neoplasms. With these methods, T1- and T2/T2*-weighted imaging sequences are used to image the distribution of gadolinium (Gd)-based contrast agents. However, it is well known that Gd exhibits combined T1, T2, and T2* shortening effects in tissue, and therefore, the results of both DCE- and DSC-MRI can be confounded by these opposing effects. In particular, residual susceptibility effects compete with T1 shortening, which can confound DCE-MRI parameters, whereas dipolar T1 and T2 leakage and residual susceptibility effects can confound DSC-MRI parameters. We introduce here a novel perfusion imaging acquisition and postprocessing method termed Spiral Perfusion Imaging with Consecutive Echoes (SPICE) that can be used to simultaneously acquire DCE- and DSC-MRI data, which requires only a single dose of the Gd contrast agent, does not require the collection of a precontrast T1 map for DCE-MRI processing, and eliminates the confounding contrast agent effects due to contrast extravasation. A detailed mathematical description of SPICE is provided here along with a demonstration of its utility in patients with high-grade glioma. PMID:28090589

  15. Uncovering spiral structure in flocculent galaxies

    CERN Document Server

    Thornley, M D

    1996-01-01

    We present K'(2.1 micron) observations of four nearby flocculent spirals, which clearly show low-level spiral structure and suggest that kiloparsec-scale spiral structure is more prevalent in flocculent spirals than previously supposed. In particular, the prototypical flocculent spiral NGC 5055 is shown to have regular, two-arm spiral structure to a radius of 4 kpc in the near infrared, with an arm-interarm contrast of 1.3. The spiral structure in all four galaxies is weaker than that in grand design galaxies. Taken in unbarred galaxies with no large, nearby companions, these data are consistent with the modal theory of spiral density waves, which maintains that density waves are intrinsic to the disk. As an alternative, mechanisms for driving spiral structure with non-axisymmetric perturbers are also discussed. These observations highlight the importance of near infrared imaging for exploring the range of physical environments in which large-scale dynamical processes, such as density waves, are important.

  16. A Multiwavelength Exploration of the Grand Design Spiral M83: The HST/WFC3 Continuum and Emission-line Imaging Survey

    Science.gov (United States)

    Blair, William P.; Long, K. S.; Winkler, P. F.; Kuntz, K. D.; Whitmore, B. C.; Soria, R.; Dopita, M. A.; Ghavamian, P.; Chandar, R.; Rangelov, B.

    2013-01-01

    As part of HST Cy19 program 12513, we have obtained WFC3 UVIS and IR camera data of five new fields in the face-on spiral M83 which, combined with two existing fields obtained in 2009 and 2010, nearly cover the entire bright disk and spiral arms. Broadband U, B, V, I, and H will permit us to characterize the ages of 100’s of star clusters as well as the general stellar disk populations as a function of spatial position. The broadband data can also be scaled and subtracted from our narrowband Ha, [S II], [O III] and [Fe II] 1.64 micron images to allow us to find and measure 100’s of supernova remnants, planetary nebulae, and other emission nebulae. Comparison of these data with each other and with deep (729 ks) Chandra data and new radio surveys with JVLA and ATCA will allow us to search for and characterize optical counterparts to many of the X-ray sources, including especially supernova remnants and X-ray binaries, and estimate the ages of the underlying host stellar populations. We will provide an overview of this rich data set and show initial results from these comparisons. This work is supported by STScI grant HST-GO-12513.01-A to the Johns Hopkins University.

  17. Integral Field Spectroscopy and multi-wavelength imaging of the nearby spiral galaxy NGC5668: an unusual flattening in metallicity gradient

    CERN Document Server

    Marino, Raffaella Anna; Castillo-Morales, Africa; Muñoz-Mateos, Juan Carlos; Sánchez, Sebastián F; Pérez-González, Pablo G; Gallego, Jesús; Zamorano, Jaime; Alonso-Herrero, Almudena; Boissier, Samuel

    2012-01-01

    We present the analysis of the full bi-dimensional optical spectral cube of the nearby spiral galaxy NGC 5668, observed with the PPAK IFU at the Calar Alto observatory 3.5m telescope. We make use of broad-band imaging to provide further constraints on the evolutionary history of the galaxy. This dataset will allow us to improve our understanding of the mechanisms that drive the evolution of disks. We investigated the properties of 62 H II regions and concentric rings in NGC 5668 and derived maps in ionized-gas attenuation and chemical (oxygen) abundances. We find that, while inwards of r\\,$\\sim\\,36",\\sim$\\,4.4kpc\\,$\\sim$\\,0.36\\,$(\\frac {D_{25}}{2})$ the derived O/H ratio follows the radial gradient typical of spiral galaxies, the abundance gradient beyond r$\\sim36"$ flattens out. The analysis of the multi-wavelength surface brightness profiles of NGC 5668 is performed by fitting these profiles with those predicted by chemo-spectrophotometric evolutionary models of galaxy disks. From this, we infer a spin and ...

  18. Diagnostic image quality of a comprehensive high-pitch dual-spiral cardiothoracic CT protocol in patients with undifferentiated acute chest pain

    Energy Technology Data Exchange (ETDEWEB)

    Bamberg, Fabian, E-mail: fbamberg@med.lmu.de [Department of Clinical Radiology, Ludwig-Maximilians University, Klinikum Grosshadern, Munich (Germany); Marcus, Roy; Sommer, Wieland; Schwarz, Florian; Nikolaou, Konstantin; Becker, Christoph R.; Reiser, Maximilian F.; Johnson, Thorsten R.C. [Department of Clinical Radiology, Ludwig-Maximilians University, Klinikum Grosshadern, Munich (Germany)

    2012-12-15

    Objective: To evaluate diagnostic image quality of high-pitch dual source comprehensive cardiothoracic CT protocol in patients presenting with acute undifferentiated chest pain. Materials and methods: Consecutive symptomatic subjects (n = 51) with undifferentiated acute chest pain underwent ECG-synchronized high-pitch dual-spiral chest CT angiography (Definition Flash, Siemens Medical Solutions, 2 × 100 kVp or 2 × 120 kV if BMI > 30, collimation: 128 × 0.6 mm, pitch: 3.2). Independent investigators determined the image quality of each cardiac and pulmonary vessel segment, measured contrast-to-noise-ratio (CNR), and determined radiation exposure. In addition, the prevalence of CT findings (pulmonary embolism (PE), aortic dissection (AD) and significant coronary stenosis (≥50%)) was determined. Univariate and multivariate analysis were performed to determine the subpopulation with highest diagnostic quality. Results: Among 51 subjects (66% male, average age: 63 ± 15.8), the prevalence of positive CT findings was moderate (overall: 11.7%). Overall, image quality of the pulmonary, aortic and coronary vasculature was good (1.26 ± 0.43 and CNR: 2.52) with an average radiation dose of 3.82 mSv and 3.2% of segments rated non-evaluable. The image quality was lowest in the coronary arteries (p = 0.02), depending on the heart rate (r = 0.52, p < 0.001). In subjects with a heart rate of ≤65 bpm (n = 30) subjective image quality and CNR of the coronary arteries were higher (1.6 ± 0.5 vs. 2.1 ± 0.5, p = 0.03 and 1.21 ± 0.3 vs. 1.02 ± 0.3, p = 0.05) with only 1.5% segments classified as non-evaluable. Conclusion: High-pitch dual-spiral comprehensive cardiothoracic CT provides low radiation exposure with excellent image quality at heart rates ≤65 bpm. In subjects with higher heart rates, image quality of the aortic and pulmonary vasculature remains excellent, while the assessment of the coronary arteries degrades substantially.

  19. Simulations of dual morphology in spiral galaxies

    CERN Document Server

    Berman, S L

    2003-01-01

    Gas and stars in spiral galaxies are modelled with the DUAL code, using hydrodynamic and N-body techniques. The simulations reveal morphological differences mirroring the dual morphologies seen in B and K' band observations of many spiral galaxies. In particular, the gaseous images are more flocculent with lower pitch angles than the stellar images, and the stellar arm-interarm contrast correlates with the degree of morphological decoupling.

  20. Improving The Contrast of Image Edge Enhancement with A New Spiral Phase Filter%基于新型螺旋相位滤波器提高图像边缘增强对比度的方法

    Institute of Scientific and Technical Information of China (English)

    李志焕; 吴福全; 陈君; 崔祥霞

    2012-01-01

    A new type of Bessel - like spiral phase filter for improving the contrast of image edge en- hancement was introduced. The analytical expressions to describe the point spread function of conventional Bessel -like spiral phase filters with topological charge were given and the edge enhancement for three differ- ent images such as circular aperture, Chinese character and onion epidermal cells were simulated. The results show that compared with the results of image edge enhancement of the conventional spiral phase filter, the con- trast of image edge enhancement with Bessel - like spiral phase filter is obviously higher.%提出了利用类贝塞尔螺旋相位滤波器实现提高图像边缘增强对比度的方法.给出了普通螺旋相位滤波器和类贝塞尔螺旋相位滤波器的点扩散函数,并利用圆孔、汉字和洋葱表皮细胞等三幅图像进行了边缘增强的模拟计算,发现与普通螺旋相位滤波器的图像边缘增强结果相比,基于类贝塞尔螺旋相位滤波器的图像边缘增强对比度得到显著提高.

  1. IR STAR FORMING KNOTS IN GRAND DESIGN SPIRAL GALAXIES: SPIRAL STRUCTURE STAR FORMATION CONNECTION

    Directory of Open Access Journals (Sweden)

    H. Dottori

    2009-01-01

    Full Text Available We are studying 46 Grand Design spirals widely spread in types, which have been imaged in the K-band with the ESO NTT telescope. Eleven objects show knots strongly associated to the m=2 Fourier component of the spiral structure. Corotation ressonance (CR for the two-armed pattern have been derived for ve galaxies.

  2. Measurements of the equivalent thicknesses of three-dimensional spiral galactic disks

    Institute of Scientific and Technical Information of China (English)

    Gang Li; Zhi-Quan Luo; Qiu-He Peng

    2009-01-01

    Spiral arms are fitted after the data from the latest spiral galactic images re-leased by the Sloan Digital Sky Survey are processed. Equivalent thicknesses of 42 spiral galactic disks are derived, which increase the foundational data for further research about spiral galaxies.

  3. High-resolution diffusion tensor imaging of the human pons with a reduced field-of-view, multishot, variable-density, spiral acquisition at 3 T.

    Science.gov (United States)

    Karampinos, Dimitrios C; Van, Anh T; Olivero, William C; Georgiadis, John G; Sutton, Bradley P

    2009-10-01

    Diffusion tensor imaging of localized anatomic regions, such as brainstem, cervical spinal cord, and optic nerve, is challenging because of the existence of significant susceptibility differences, severe physiologic motion in the surrounding tissues, and the need for high spatial resolution to resolve the underlying complex neuroarchitecture. The aim of the methodology presented here is to achieve high-resolution diffusion tensor imaging in localized regions of the central nervous system that is motion insensitive and immune to susceptibility while acquiring a set of two-dimensional images with more than six diffusion encoding directions within a reasonable total scan time. We accomplish this aim by implementing self-navigated, multishot, variable-density, spiral encoding with outer volume suppression. We establish scan protocols for achieving equal signal-to-noise ratio at 1.2 mm and 0.8 mm in-plane resolution for reduced field-of-view diffusion tensor imaging of the brainstem. In vivo application of the technique on the human pons of three subjects shows a clear delineation of the multiple local neural tracts. By comparing scans acquired with varying in-plane resolution but with constant signal-to-noise ratio, we demonstrate that increasing the resolution and reducing the partial volume effect result in higher fractional anisotropy values for the corticospinal tracts. (c) 2009 Wiley-Liss, Inc.

  4. Nuclear spirals in galaxies

    OpenAIRE

    Maciejewski, Witold

    2006-01-01

    Recent high-resolution observations indicate that nuclear spirals are often present in the innermost few hundred parsecs of disc galaxies. My models show that nuclear spirals form naturally as a gas response to non-axisymmetry in the gravitational potential. Some nuclear spirals take the form of spiral shocks, resulting in streaming motions in the gas, and in inflow comparable to the accretion rates needed to power local Active Galactic Nuclei. Recently streaming motions of amplitude expected...

  5. Use of NMR Imaging to Determine the Diffusion Coefficient of Water in Bio-based Hydrogels

    Science.gov (United States)

    The diffusion of liquid in a hydrogel material is a fundamental property which must be controlled in order to create effective delivery systems for the agricultural and pharmaceutical industries. NMR spectroscopy has been used to determine the diffusion of water and deuterium oxide in a bio-based h...

  6. Computational Diffusion Magnetic Resonance Imaging Based on Time-Dependent Bloch NMR Flow Equation and Bessel Functions.

    Science.gov (United States)

    Awojoyogbe, Bamidele O; Dada, Michael O; Onwu, Samuel O; Ige, Taofeeq A; Akinwande, Ninuola I

    2016-04-01

    Magnetic resonance imaging (MRI) uses a powerful magnetic field along with radio waves and a computer to produce highly detailed "slice-by-slice" pictures of virtually all internal structures of matter. The results enable physicians to examine parts of the body in minute detail and identify diseases in ways that are not possible with other techniques. For example, MRI is one of the few imaging tools that can see through bones, making it an excellent tool for examining the brain and other soft tissues. Pulsed-field gradient experiments provide a straightforward means of obtaining information on the translational motion of nuclear spins. However, the interpretation of the data is complicated by the effects of restricting geometries as in the case of most cancerous tissues and the mathematical concept required to account for this becomes very difficult. Most diffusion magnetic resonance techniques are based on the Stejskal-Tanner formulation usually derived from the Bloch-Torrey partial differential equation by including additional terms to accommodate the diffusion effect. Despite the early success of this technique, it has been shown that it has important limitations, the most of which occurs when there is orientation heterogeneity of the fibers in the voxel of interest (VOI). Overcoming this difficulty requires the specification of diffusion coefficients as function of spatial coordinate(s) and such a phenomenon is an indication of non-uniform compartmental conditions which can be analyzed accurately by solving the time-dependent Bloch NMR flow equation analytically. In this study, a mathematical formulation of magnetic resonance flow sequence in restricted geometry is developed based on a general second order partial differential equation derived directly from the fundamental Bloch NMR flow equations. The NMR signal is obtained completely in terms of NMR experimental parameters. The process is described based on Bessel functions and properties that can make it

  7. INTEGRAL FIELD SPECTROSCOPY AND MULTI-WAVELENGTH IMAGING OF THE NEARBY SPIRAL GALAXY NGC 5668 : AN UNUSUAL FLATTENING IN METALLICITY GRADIENT

    Energy Technology Data Exchange (ETDEWEB)

    Marino, R. A.; Gil de Paz, A.; Castillo-Morales, A.; Perez-Gonzalez, P. G.; Gallego, J.; Zamorano, J. [CEI Campus Moncloa, UCM-UPM, Departamento de Astrofisica y CC. de la Atmosfera, Facultad de CC. Fisicas, Universidad Complutense de Madrid, Avda. Complutense s/n, 28040 Madrid (Spain); Munoz-Mateos, J. C. [National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903-2475 (United States); Sanchez, S. F. [Centro Astronomico Hispano Aleman, Calar Alto (CSIC-MPG), C/Jesus Durban Remon 2-2, E-04004 Almeria (Spain); Alonso-Herrero, A. [Instituto de Fisica de Cantabria, CSIC-UC, Avenida de los Castros s/n, 39005 Santander (Spain); Boissier, S., E-mail: ramarino@fis.ucm.es [Laboratoire dAstrophysique de Marseille, OAMP, Universite Aix-Marseille and CNRS UMR 6110, 38 rue Frederic Joliot-Curie, 13388 Marseille cedex 13 (France)

    2012-07-20

    We present an analysis of the full bidimensional optical spectral cube of the nearby spiral galaxy NGC 5668, observed with the Pmas fiber PAcK Integral Field Unit (IFU) at the Calar Alto observatory 3.5 m telescope. We make use of broadband imaging to provide further constraints on the evolutionary history of the galaxy. This data set will allow us to improve our understanding of the mechanisms that drive the evolution of disks. We investigated the properties of 62 H II regions and concentric rings in NGC 5668 and derived maps in ionized-gas attenuation and chemical (oxygen) abundances. We find that while inward of r {approx}36'' {approx} 4.4 kpc {approx} 0.36 (D{sub 25}/2) the derived O/H ratio follows the radial gradient typical of spiral galaxies, the abundance gradient beyond r {approx} 36'' flattens out. The analysis of the multi-wavelength surface brightness profiles of NGC 5668 is performed by fitting these profiles with those predicted by chemo-spectrophotometric evolutionary models of galaxy disks. From this, we infer a spin and circular velocity of {lambda} = 0.053 and v{sub c} = 167 km s{sup -1}, respectively. The metallicity gradient and rotation curve predicted by this best-fitting galaxy model nicely match the values derived from the IFU observations, especially within r {approx}36''. The same is true for the colors despite some small offsets and a reddening in the bluest colors beyond that radius. On the other hand, deviations of some of these properties in the outer disk indicate that a secondary mechanism, possibly gas transfer induced by the presence of a young bar, must have played a role in shaping the recent chemical and star formation histories of NGC 5668.

  8. Rebuilding Spiral Galaxies

    Science.gov (United States)

    2005-01-01

    occurring in less than 1,000 million years, the existence of such a large fraction of these LIRGs in the past Universe has important consequences on the total stellar formation rate. As François Hammer (Paris Observatory, France), leader of the team, states: "We are thus led to the conclusion that during the time span from roughly 8,000 million to 4,000 million years ago, intermediate mass galaxies converted about half of their total mass into stars. Moreover, this star formation must have taken place in very intense bursts when galaxies were emitting huge amount of infrared radiation and appeared as LIRGs." Another result could be secured using the spectra obtained with the Very Large Telescope: the astronomers measured the chemical abundances in several of the observed galaxies (PR Photo 02a/05). They find that galaxies with large redshifts show oxygen abundances two times lower than present-day spirals. As it is stars which produce oxygen in a galaxy, this again gives support to the fact that these galaxies have been actively forming stars in the period between 8,000 and 4,000 million years ago. And because it is believed that galaxy collisions and mergers play an important role in triggering such phases of enhanced star-forming activity, these observations indicate that galaxy merging still occurred frequently less than 8,000 million years ago. Spiral Rebuilding ESO PR Photo 02b/05 ESO PR Photo 02b/05 The Spiral Rebuilding Scenario [Preview - JPEG: 471 x 400 pix - 80k] [Normal - JPEG: 941 x 800 pix - 207k] Caption: ESO PR Photo 02b/05: Schematic representation of the newly proposed scenario of "spiral galaxy rebuilding": galaxies collide (1), then merge (2), inducing a burst of stellar formation activity. After the merging, the gas and the stars fall towards the centre in a very compact structure (3). Part of the gas which did not fall back initially, gradually rebuilds a disc around the compact structure, making a new spiral galaxy (4 and 5). The images are pictures

  9. Mathematical Development and Computational Analysis of Harmonic Phase-Magnetic Resonance Imaging (HARP-MRI) Based on Bloch Nuclear Magnetic Resonance (NMR) Diffusion Model for Myocardial Motion.

    Science.gov (United States)

    Dada, Michael O; Jayeoba, Babatunde; Awojoyogbe, Bamidele O; Uno, Uno E; Awe, Oluseyi E

    2017-09-13

    Harmonic Phase-Magnetic Resonance Imaging (HARP-MRI) is a tagged image analysis method that can measure myocardial motion and strain in near real-time and is considered a potential candidate to make magnetic resonance tagging clinically viable. However, analytical expressions of radially tagged transverse magnetization in polar coordinates (which is required to appropriately describe the shape of the heart) have not been explored because the physics required to directly connect myocardial deformation of tagged Nuclear Magnetic Resonance (NMR) transverse magnetization in polar geometry and the appropriate harmonic phase parameters are not yet available. The analytical solution of Bloch NMR diffusion equation in spherical geometry with appropriate spherical wave tagging function is important for proper analysis and monitoring of heart systolic and diastolic deformation with relevant boundary conditions. In this study, we applied Harmonic Phase MRI method to compute the difference between tagged and untagged NMR transverse magnetization based on the Bloch NMR diffusion equation and obtained radial wave tagging function for analysis of myocardial motion. The analytical solution of the Bloch NMR equations and the computational simulation of myocardial motion as developed in this study are intended to significantly improve healthcare for accurate diagnosis, prognosis and treatment of cardiovascular related deceases at the lowest cost because MRI scan is still one of the most expensive anywhere. The analysis is fundamental and significant because all Magnetic Resonance Imaging techniques are based on the Bloch NMR flow equations.

  10. Organ specific mapping of in vivo redox state in control and cigarette smoke-exposed mice using EPR/NMR co-imaging

    Science.gov (United States)

    Caia, George L.; Efimova, Olga V.; Velayutham, Murugesan; El-Mahdy, Mohamed A.; Abdelghany, Tamer M.; Kesselring, Eric; Petryakov, Sergey; Sun, Ziqi; Samouilov, Alexandre; Zweier, Jay L.

    2012-03-01

    In vivo mapping of alterations in redox status is important for understanding organ specific pathology and disease. While electron paramagnetic resonance imaging (EPRI) enables spatial mapping of free radicals, it does not provide anatomic visualization of the body. Proton MRI is well suited to provide anatomical visualization. We applied EPR/NMR co-imaging instrumentation to map and monitor the redox state of living mice under normal or oxidative stress conditions induced by secondhand cigarette smoke (SHS) exposure. A hybrid co-imaging instrument, EPRI (1.2 GHz)/proton MRI (16.18 MHz), suitable for whole-body co-imaging of mice was utilized with common magnet and gradients along with dual EPR/NMR resonators that enable co-imaging without sample movement. The metabolism of the nitroxide probe, 3-carbamoyl-proxyl (3-CP), was used to map the redox state of control and SHS-exposed mice. Co-imaging allowed precise 3D mapping of radical distribution and reduction in major organs such as the heart, lungs, liver, bladder and kidneys. Reductive metabolism was markedly decreased in SHS-exposed mice and EPR/NMR co-imaging allowed quantitative assessment of this throughout the body. Thus, in vivo EPR/NMR co-imaging enables in vivo organ specific mapping of free radical metabolism and redox stress and the alterations that occur in the pathogenesis of disease.

  11. Reflections on love's spirals.

    Science.gov (United States)

    Kenny, Gerard

    2011-06-01

    This article seeks to explore how the experience of love and its expression might inform and guide reflection and inquiry into love. Despite the importance of love in our personal and professional lives, it remains a topic that has further scope for inquiry within nursing circles. The article takes as its catalyst an encounter that emerged out of a piece of research that was exploring individuals' experiences of becoming healers and the journey they undertook. One participant spoke deeply and profoundly of his experience of love, which generated for me a personal, experiential, and intellectual process of inquiry. The article seeks to try and create a synthesis between rational inquiry and subjective experience. It explores W. B. Yeats's notion of a gyre, a spiral, as an image and metaphor for integrating different conceptions and understandings of love. It seeks to illustrate how a more integrated understanding of love may open up spaces of inquiry that are more flexible, creative, and spontaneous.

  12. Noninvasive assessment of coronary artery disease by multislice spiral computed tomography using a new retrospectively ECG-gated image reconstruction technique. Comparison with angiographic results

    Energy Technology Data Exchange (ETDEWEB)

    Sato, Yuichi; Matsumoto, Naoya; Kato, Masahiko [Nihon Univ., Tokyo (Japan). Surugadai Hospital] [and others

    2003-04-01

    The present study was designed to investigate the accuracy of multislice spiral computed tomography (MSCT) in detecting coronary artery disease, compared with coronary angiography (CAG), using a new retrospectively ECG-gated reconstruction method that reduced cardiac motion artifact. The study group comprised 54 consecutive patients undergoing MSCT and CAG. MSCT was performed using a SOMATOM Volume Zoom (4-detector-row, Siemens, Germany) with slice thickness 1.0 mm, pitch 1.5 (table feed: 1.5 mm per rotation) and gantry rotation time 500 ms. Metoprolol (20-60 mg) was administered orally prior to MSCT imaging. ECG-gated image reconstruction was performed with the reconstruction window (250 ms) positioned immediately before atrial contraction in order to reduce the cardiac motion artifact caused by the abrupt diastolic ventricular movement occurring during the rapid filling and atrial contraction periods. Following inspection of the volume rendering images, multiplanar reconstruction images and axial images of the left main coronary artery (LMCA), left anterior descending artery (LAD), left circumflex artery (LCx) and right coronary artery (RCA) were obtained and evaluated for luminal narrowing. The results were compared with those obtained by CAG. Of 216 coronary arteries, 206 (95.4%) were assessable; 10 arteries were excluded from the analysis because of severe calcification (n=4), stents (n=3) or insufficient contrast enhancement (n=3). The sensitivity to detect coronary stenoses {>=}50% was 93.5% and the specificity to define luminal narrowing <50% was 97.2%. The positive predictive value and the negative predictive value were 93.5% and 97.2%, respectively. The sensitivity was still satisfactory (80.6%) even when non-assessable arteries were included in the analysis. The new retrospectively ECG-gated reconstruction method for MSCT has excellent diagnostic accuracy in detecting significant coronary artery stenoses. (author)

  13. The Structure of Nuclear Star Clusters in Nearby Late-type Spiral Galaxies from Hubble Space Telescope Wide Field Camera 3 Imaging

    CERN Document Server

    Carson, Daniel J; Seth, Anil C; Brok, Mark den; Cappelari, Michele; Greene, Jenny E; Ho, Luis C; Neumayer, Nadine

    2015-01-01

    We obtained Hubble Space Telescope/Wide Field Camera 3 imaging of a sample of ten of the nearest and brightest nuclear clusters residing in late-type spiral galaxies, in seven bands that span the near-ultraviolet to the near-infrared. Structural properties of the clusters were measured by fitting two-dimensional surface brightness profiles to the images using GALFIT. The clusters exhibit a wide range of structural properties. For six of the ten clusters in our sample, we find changes in the effective radius with wavelength, suggesting radially varying stellar populations. In four of the objects, the effective radius increases with wavelength, indicating the presence of a younger population which is more concentrated than the bulk of the stars in the cluster. However, we find a general decrease in effective radius with wavelength in two of the objects in our sample, which may indicate extended, circumnuclear star formation. We also find a general trend of increasing roundness of the clusters at longer waveleng...

  14. Globular Cluster Systems of Spiral and S0 Galaxies: Results from WIYN Imaging of NGC1023, NGC1055, NGC7332 and NGC7339

    CERN Document Server

    Young, Michael D; Rhode, Katherine L

    2012-01-01

    We present results from a study of the globular cluster (GC) systems of four spiral and S0 galaxies imaged as part of an ongoing wide-field survey of the GC systems of giant galaxies. The target galaxies -- the SB0 galaxy NGC1023, the SBb galaxy NGC1055, and an isolated pair comprised of the Sbc galaxy NGC7339 and the S0 galaxy NGC7332 -- were observed in BVR filters with the WIYN 3.5-m telescope and Minimosaic camera. For two of the galaxies, we combined the WIYN imaging with previously-published data from the Hubble Space Telescope and the Keck Observatory to help characterize the GC distribution in the central few kiloparsecs. We determine the radial distribution (surface density of GCs versus projected radius) of each galaxy's GC system and use it to calculate the total number of GCs (N_GC). We find N_GC = 490+/-30, 210+/-40, 175+/-15, and 75+/-10 for NGC1023, NGC1055, NGC7332, and NGC7339, respectively. We also calculate the GC specific frequency (N_GC normalized by host galaxy luminosity or mass) and fi...

  15. HST Imaging of Dust Structures and Stars in the Ram Pressure Stripped Virgo Spirals NGC 4402 and NGC 4522: Stripped from the Outside In with Dense Cloud Decoupling

    CERN Document Server

    Abramson, A; Crowl, H; Tal, T

    2016-01-01

    We describe and constrain the origins of ISM structures likely created by ongoing ICM ram pressure stripping in two Virgo Cluster spirals, NGC 4522 and NGC 4402, using HST BVI images of dust extinction and stars, as well as supplementary HI, Halpha, and radio continuum images. This is the highest-resolution study to date of the physical processes that occur during an ICM-ISM ram pressure stripping interaction, ram pressure stripping's effects on the multi-phase, multi-density ISM, and the formation and evolution of ram-pressure-stripped tails. In dust extinction, we view the leading side of NGC 4402 and the trailing side of NGC 4522; we see distinct types of features in both galaxies. NGC 4522 has experienced stronger, more recent pressure and has the jellyfish morphology characteristic of some ram pressure stripped galaxies. Its stripped tail extends up from the disk plane in continuous upturns of dust and stars curving ~2 kpc above the disk plane. A kinematically and morphologically distinct extraplanar arm...

  16. Application of imaging postprocessing of spiral CT in the staging of lung cancer%螺旋CT后处理技术在肺癌新分期中的临床价值

    Institute of Scientific and Technical Information of China (English)

    Zhiming Xiang; Fang Huang; Cuimei Liang; Xiangdong Xu; Lilian Tan

    2008-01-01

    Objective:To evaluate the role of spiral CT imaging postprocessing techniques in preoperative TNM staging of lung cancer.Methods:106 patients with pathologically confirmed lung cancer received spiral CT examinations with a new revised TNM staging method of lung cancer which was taken as criterion of diagnosis.The images were reconstructed by using different postprecessing techniques such as MPR,MIP,SSD,VR,and their TNM staging capabilities were assessed by using postprocessing imaging and the results with axial CT images were compared.Results:In T staging,the accurate rates of axial CT images in T1-T4 staging were 77.3%,60.6%,60.7%,and 60.3% respectively; for postprocessing images,the accurate rates were 86.4%,90.9%,89.3%,and 87.0% respectively.In N staging,the accurate rates of axial CT images were 84.6%,68.1%,63.6%,and 64.2% in NO-N3 staging,respectively; but they were 92.3%,90.9%,90.9%,and 85.7% in postprocessing images,respectively.The postprocessing images were superior to axial CT images in T1-T3 and N1-N3 staging of lung cancer but there were no significant differences in T1 and NO staging.For metastasis,the postprocessing images may be helpful for the TNM staging of lung cancer.Conclusion:The postprocessing techniques of the spiral CT could improve the accurate rates of TNM staging of lung cancer,and represent a useful complement to the axial CT.

  17. Assessment of spiral CT pneumocolon in preoperative colorectal carcinoma

    Institute of Scientific and Technical Information of China (English)

    Can-Hui Sun; Zi-Ping Li; Quan-Fei Meng; Shen-Ping Yu; Da-Sheng Xu

    2005-01-01

    AIM: To investigate the value of spiral CT pneumocolon in preoperative colorectal carcinoma.METHODS: Spiral CT pneumocolon was performed prior to surgery in 64 patients with colorectal carcinoma. Spiral CT images were compared to specimens from the resected tumor.RESULTS: Spiral CT depicted the tumor in all patients.Comparison of spiral CT and histologic results showed that the sensitivity and specificity were 95.2%, 40.9% in detection of local invasion, and 75.0%, 90.9% in detection of lymph node metastasis. Compared to the Dukes classification,the disease was correctly staged as A in 6 of 18 patients,as B in 18 of 23, as C in 10 of 15, and as D in 7 of 8. Overall,spiral CT correctly staged 64.1% of patients.CONCLUSION: Spiral CT pneumocolon may be useful in the preoperative assessment of patients with colorectal carcinoma as a means for assisting surgical planning.

  18. Electromechanics of graphene spirals

    Directory of Open Access Journals (Sweden)

    Topi Korhonen

    2014-12-01

    Full Text Available Among the most fascinating nanostructure morphologies are spirals, hybrids of somewhat obscure topology and dimensionality with technologically attractive properties. Here, we investigate mechanical and electromechanical properties of graphene spirals upon elongation by using density-functional tight-binding, continuum elasticity theory, and classical force field molecular dynamics. It turns out that electronic properties are governed by interlayer interactions as opposed to strain effects. The structural behavior is governed by van der Waals interaction: in its absence spirals unfold with equidistant layer spacings, ripple formation at spiral perimeter, and steadily increasing axial force; in its presence, on the contrary, spirals unfold via smooth local peeling, complex geometries, and nearly constant axial force. These electromechanical trends ought to provide useful guidelines not only for additional theoretical investigations but also for forthcoming experiments on graphene spirals.

  19. Electromechanics of graphene spirals

    Energy Technology Data Exchange (ETDEWEB)

    Korhonen, Topi; Koskinen, Pekka, E-mail: pekka.koskinen@iki.fi [NanoScience Center, Department of Physics, University of Jyväskylä, 40014 Jyväskylä (Finland)

    2014-12-15

    Among the most fascinating nanostructure morphologies are spirals, hybrids of somewhat obscure topology and dimensionality with technologically attractive properties. Here, we investigate mechanical and electromechanical properties of graphene spirals upon elongation by using density-functional tight-binding, continuum elasticity theory, and classical force field molecular dynamics. It turns out that electronic properties are governed by interlayer interactions as opposed to strain effects. The structural behavior is governed by van der Waals interaction: in its absence spirals unfold with equidistant layer spacings, ripple formation at spiral perimeter, and steadily increasing axial force; in its presence, on the contrary, spirals unfold via smooth local peeling, complex geometries, and nearly constant axial force. These electromechanical trends ought to provide useful guidelines not only for additional theoretical investigations but also for forthcoming experiments on graphene spirals.

  20. A novel nuclear magnetic resonance (NMR) imaging method for measuring the water front penetration rate in hydrophilic polymer matrix capsule plugs and its role in drug release.

    Science.gov (United States)

    Ashraf, M; Iuorno, V L; Coffin-Beach, D; Evans, C A; Augsburger, L L

    1994-05-01

    An NMR imaging method was developed to estimate the rate of water movement in slow-release capsule matrices of pseudoephdrine HCl and hydroxypropyl cellulose (HPC). Test capsules were first placed in a USP method 2 (paddles, 50 rpm) dissolution apparatus. Each plug was removed from the dissolution medium at predetermined times, blotted dry, and placed within the magnetic field of a General Electric 400-MHz wide-bore NMR spectrometer equipped with a microimaging accessory. Images were recorded along the transverse plane of each plug. The water penetration rate was determined by comparison of the cut and weighed contour plots of the images acquired. After 1 hr, the plugs tamped to 200 N exhibited water penetration to the center, while only 45% of the drug was released. The percentage dry matrix was fitted to the Jost equation to obtain a diffusion coefficient of 4.15 x 10(-6) cm2/sec. NMR imaging is set forth as an important and practicable technique to investigate drug formulations. In the HPC matrix system of this study, the NMR imaging results convincingly revealed the rate of hydration front penetration not to be a rate-limiting step in the drug release process.

  1. On the suppression of background signals originating from NMR hardware components. Application to zero echo time imaging and relaxation time analysis.

    Science.gov (United States)

    Dreher, Wolfgang; Bardenhagen, Ingo; Huang, Li; Bäumer, Marcus

    2016-04-01

    Modern NMR imaging systems used for biomedical research are equipped with B0 gradient systems with strong maximum gradient strength and short switching time enabling (1)H NMR measurements of samples with very short transverse relaxation times. However, background signal originating from non-optimized RF coils may hamper experiments with ultrashort delays between RF excitation and signal reception. We demonstrate that two simple means, outer volume suppression and the use of shaped B0 fields produced by higher-order shim coils, allow a considerable suppression of disturbing background signals. Thus, the quality of NMR images acquired at ultrashort or zero echo time is improved and systematic errors in quantitative data evaluation are avoided. Fields of application comprise MRI with ultrashort echo time or relaxation time analysis, for both biomedical research and characterizing porous media filled with liquids or gases.

  2. Comparison of Image Registration Based Measures of Regional Lung Ventilation from Dynamic Spiral CT with Xe-CT

    CERN Document Server

    Ding, Kai; Fuld, Matthew K; Du, Kaifang; Christensen, Gary E; Hoffman, Eric A; Reinhardt, Joseph M

    2012-01-01

    Purpose: Regional lung volume change as a function of lung inflation serves as an index of parenchymal and airway status as well as an index of regional ventilation and can be used to detect pathologic changes over time. In this article, we propose a new regional measure of lung mechanics --- the specific air volume change by corrected Jacobian. Methods: 4DCT and Xe-CT data sets from four adult sheep are used in this study. Nonlinear, 3D image registration is applied to register an image acquired near end inspiration to an image acquired near end expiration. Approximately 200 annotated anatomical points are used as landmarks to evaluate registration accuracy. Three different registration-based measures of regional lung mechanics are derived and compared: the specific air volume change calculated from the Jacobian (SAJ); the specific air volume change calculated by the corrected Jacobian (SACJ); and the specific air volume change by intensity change (SAI). Results: After registration, the mean registration err...

  3. Estimating the surface relaxivity as a function of pore size from NMR T2 distributions and micro-tomographic images

    Science.gov (United States)

    Benavides, Francisco; Leiderman, Ricardo; Souza, Andre; Carneiro, Giovanna; Bagueira, Rodrigo

    2017-09-01

    In the present work, we formulate and solve an inverse problem to recover the surface relaxivity as a function of pore size. The input data for our technique are the T2 distribution measurement and the micro-tomographic image of the rock sample under investigation. We simulate the NMR relaxation signal for a given surface relaxivity function using the random walk method and rank different surface relaxivity functions according to the correlation of the resulting simulated T2 distributions with the measured T2 distribution. The optimization is performed using genetic algorithms and determines the surface relaxivity function whose corresponding simulated T2 distribution best matches the measured T2 distribution. In the proposed methodology, pore size is associated with a number of collisions in the random walk simulations. We illustrate the application of the proposed method by performing inversions from synthetic and laboratory input data and compare the obtained results with those obtained using the uniform relaxivity assumption.

  4. NMR imaging of root water distribution in intact Vicia faba L plants in elevated atmospheric CO[sub 2

    Energy Technology Data Exchange (ETDEWEB)

    Bottomley, P.A.; Rogers, H.H.; Prior, S.A. (GE Research and Development Center, Schenectady, NY (USA))

    1993-04-01

    The effect of elevated atmospheric CO[sub 2] on water distribution in the intact roots of Vicia faba L. bean seedlings grown in natural soil was studied noninvasively with proton ([sup 1]H) nuclear magnetic resonance (NMR) imaging. Exposure of 24-d-old plants to atmospheric CO[sub 2] enriched air at 650 cm[sup 3] m[sup -3] produced significant increases in water imaged in upper roots, hypogeal cotyledons and lower stems in response to a short-term drying-stress cycle. Above ground, drying produced negligible stem shrinkage and stomatal resistance was unchanged. In contrast, the same drying cycle caused significant depletion of water imaged in the same upper root structures in control plants subject to ambient CO[sub 2] (350 cm[sup 3] m[sup -3]), and stem shrinkage and increased stomatal resistance. The results suggest that inhibition of transpiration caused by elevated CO[sub 2] does not necessarily result in attenuation of water transport from lower root structures. Inhibition of water loss from upper roots and lower stem in elevated CO[sub 2] environments may be a mitigating factor in assessing deleterious effects of greenhouse changes on crops during periods of dry climate.

  5. The TMS34010 graphic processor - an architecture for image visualization in NMR tomography; O processador grafico TMS34010 - uma arquitetura para visualizacao de imagem em tomografia por RMN

    Energy Technology Data Exchange (ETDEWEB)

    Slaets, Jan Frans Willem; Paiva, Maria Stela Veludo de; Almeida, Lirio O.B

    1989-12-31

    This abstract presents a description of the minimum system implemented with the graphic processor TMS34010, which will be used in the reconstruction, treatment and interpretation f images obtained by NMR tomography. The project is being developed in the LIE (Electronic Instrumentation Laboratory), of the Sao Carlos Chemistry and Physical Institute, S P, Brazil and is already in operation 4 refs., 7 figs.

  6. Genesis of spiral galaxies

    CERN Document Server

    Kiselev, Valery V

    2013-01-01

    Enigmatic spiral structure of many galaxies and its huge orbital momentum originated due to the capture of lightweight bare black hole by gravity of heavy primordial gas cloud at large impact parameter. The rotating of black hole caused the formation of accretion disc from the cloud and the transfer of orbital momentum to the disc, while during the fall to the center of mass, the spiral trace of black hole in the disc did create the spiral front line of sound waves in the gas, that further evolved into the stellar spiral arms. This mechanism opens the way to study features of spiral galaxy formation, say, an influence and a significance of dark matter in this process.

  7. Zero quantum NMR imaging and spectroscopy in a low homogeneity magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Hall, L.D.; Norwood, T.J.

    1987-10-27

    This patent describes a method of obtaining zero-quantum coherence resolved images and spectra from a spin system substance in an inhomogeneous or low homogeneity magnetic field which comprises applying to the substance a pulse and spatial encoding sequence.

  8. Image quality of ultra-low radiation exposure coronary CT angiography with an effective dose <0.1 mSv using high-pitch spiral acquisition and raw data-based iterative reconstruction

    Energy Technology Data Exchange (ETDEWEB)

    Schuhbaeck, Annika; Achenbach, Stephan; Hecker, Franziska; Rixe, Johannes [University of Giessen, Department of Cardiology, Giessen (Germany); Layritz, Christian; Eisentopf, Jasmin; Pflederer, Tobias; Gauss, Soeren; Kalender, Willi; Daniel, Werner G.; Lell, Michael; Ropers, Dieter [University of Erlangen, Departments of Cardiology and Radiology, Erlangen (Germany)

    2013-03-15

    We evaluated the potential of prospectively ECG-triggered high-pitch spiral acquisition with low tube voltage and current in combination with iterative reconstruction to achieve coronary CT angiography with sufficient image quality at an effective dose below 0.1 mSv. Contrast-enhanced coronary dual source CT angiography (2 x 128 x 0.6 mm, 80 kV, 50 mAs) in prospectively ECG-triggered high-pitch spiral acquisition mode was performed in 21 consecutive individuals (body weight <100 kg, heart rate {<=}60/min). Images were reconstructed with raw data-based filtered back projection (FBP) and iterative reconstruction (IR). Image quality was assessed on a 4-point scale (1 = no artefacts, 4 = unevaluable). Mean effective dose was 0.06 {+-} 0.01 mSv. Image noise was significantly reduced in IR (128.9 {+-} 46.6 vs. 158.2 {+-} 44.7 HU). The mean image quality score was lower for IR (1.9 {+-} 1.1 vs. 2.2 {+-} 1.0, P < 0.0001). Of 292 coronary segments, 55 in FBP and 40 in IR (P = 0.12) were graded ''unevaluable''. In patients with a body weight {<=}75 kg, both in FBP and in IR, the rates of fully evaluable segments were significantly higher in comparison to patients >75 kg. Coronary CT angiography with an estimated effective dose <0.1 mSv may provide sufficient image quality in selected patients through the combination of high-pitch spiral acquisition and raw data-based iterative reconstruction. (orig.)

  9. SIGNATURES OF LONG-LIVED SPIRAL PATTERNS

    Energy Technology Data Exchange (ETDEWEB)

    Martinez-Garcia, Eric E. [Instituto Nacional de Astrofisica, Optica y Electronica (INAOE), Aptdo. Postal 51 y 216, 72000 Puebla, Pue. (Mexico); Gonzalez-Lopezlira, Rosa A., E-mail: ericmartinez@inaoep.mx, E-mail: martinez@astro.unam.mx, E-mail: r.gonzalez@crya.unam.mx [Centro de Radioastronomia y Astrofisica, UNAM, Campus Morelia, Michoacan, C.P. 58089 (Mexico)

    2013-03-10

    Azimuthal age/color gradients across spiral arms are a signature of long-lived spirals. From a sample of 19 normal (or weakly barred) spirals where we have previously found azimuthal age/color gradient candidates, 13 objects were further selected if a two-armed grand-design pattern survived in a surface density stellar mass map. Mass maps were obtained from optical and near-infrared imaging, by comparison with a Monte Carlo library of stellar population synthesis models that allowed us to obtain the mass-to-light ratio in the J band, (M/L){sub J}, as a function of (g - i) versus (i - J) color. The selected spirals were analyzed with Fourier methods in search of other signatures of long-lived modes related to the gradients, such as the gradient divergence toward corotation, and the behavior of the phase angle of the two-armed spiral in different wavebands, as expected from theory. The results show additional signatures of long-lived spirals in at least 50% of the objects.

  10. Arm & Interarm Star Formation in Spiral Galaxies

    CERN Document Server

    Foyle, Kelly; Walter, Fabian; Leroy, Adam

    2010-01-01

    We investigate the relationship between spiral arms and star formation in the grand-design spirals NGC 5194 and NGC 628 and in the flocculent spiral NGC 6946. Filtered maps of near-IR (3.6 micron) emission allow us to identify "arm regions" that should correspond to regions of stellar mass density enhancements. The two grand-design spirals show a clear two-armed structure, while NGC 6946 is more complex. We examine these arm and interarm regions, looking at maps that trace recent star formation - far-ultraviolet (GALEX NGS) and 24 micron emission (Spitzer, SINGS) - and cold gas - CO (Heracles) and HI (Things). We find the star formation tracers and CO more concentrated in the spiral arms than the stellar 3.6 micron flux. If we define the spiral arms as the 25% highest pixels in the filtered 3.6 micron images, we find that the majority (60%) of star formation tracers occurs in the interarm regions; this result persists qualitatively even when considering the potential impact of finite data resolution and diffu...

  11. Characterization of focal liver lesions with a new ultrasound contrast agent using continuous low acoustic power imaging: comparison with contrast enhanced spiral CT; Caratterizzazione delle lesioni focali epatiche con mezzo di contrasto ecografico e metodica di imaging continuo a basso indice meccanico: paragone con la TC spirale con contrasto

    Energy Technology Data Exchange (ETDEWEB)

    Passamonti, Matteo; Vercelli, Alessandro; Azzaretti, Andrea; Rodolico, Giuseppe; Calliada, Fabrizio [Ospedale Maggiore di Lodi, U. O. Radiologia, Lodi (Italy)

    2005-04-01

    Purpose: To evaluate the concordance of the enhancement patterns of a new ultrasound contrast agent (SonoVue) with those obtained with dual-phase contrast-enhanced spiral CT (CE-CT) in the characterization of focal liver lesions (FLLs). Materials and methods: Sitxty-two patients with focal liver lesions discovered at ultrasound and also studied with CECT underwent contrast-enhanced ultrasound using continuous low acoustic power imaging after receiving a 2.4 ml bolus of the new US contrast agent SonoVue, consisting of a dispersion of sulphur hexafluoride micro bubbles. The examinations were made using ATL HDI-5000, Acuson SEQUOIA and Aloka 5500 Prosound ultrasound systems with 5.2 MHz curved-array probes. The concordance between US and CE-CT images was evaluated on site by two radiologists blinded to CT results. The FLLs were assessed in the arterial (20 s after CM injection), portal (after 45-60 s) and late (after 120 s) phases for: 1) presence/absence of enhancement, 2) distribution of enhancement (homogenous or target distribution, centripetal or centrifugal flow, and other), 3) qualitative enhancement pattern (hyper-echoic, hypoechoic, or isoechoic) versus normal liver parenchyma. Results: The concordance between SonoVue-enhanced US and CE-CT was 85%. Moreover during portal venous phase with CEUS it was possible to differentiate between malignancy or benignity of 91% of lesions. Conclusions: The preliminary data obtained in this study suggest that continuous low acoustic power imaging and contrast-enhanced US show similar results to CT in contrast distribution and contrast enhancement patterns. [Italian] Scopo: Valutare la concordanza dei pattern di enhancement ottenuti con un nuovo ecocontrasto, SonoVue, con i noti pattern contrastografici della TC spirale multifasica nella caratterizzazione delle lesioni focali epatiche. Materiale e metodi: Sessantadue pazienti con lesioni focali epatiche diagnosticate ad un esame ecografico e con esame TC con contrasto, sono

  12. Superluminous Spiral Galaxies

    CERN Document Server

    Ogle, Patrick M; Nader, Cyril; Helou, George

    2015-01-01

    We report the discovery of spiral galaxies that are as optically luminous as elliptical brightest cluster galaxies, with r-band monochromatic luminosity L_r=8-14L* (4.3-7.5E44 erg/s). These super spiral galaxies are also giant and massive, with diameter D=57-134 kpc and stellar mass M_stars=0.3-3.4E11 M_sun. We find 53 super spirals out of a complete sample of 1,616 SDSS galaxies with redshift z8L*. The closest example is found at z=0.089. We use existing photometry to estimate their stellar masses and star formation rates (SFRs). The SDSS and WISE colors are consistent with normal star-forming spirals on the blue sequence. However, the extreme masses and rapid SFRs of 5-65 M_sun/yr place super spirals in a sparsely populated region of parameter space, above the star-forming main sequence of disk galaxies. Super spirals occupy a diverse range of environments, from isolation to cluster centers. We find four super spiral galaxy systems that are late-stage major mergers--a possible clue to their formation. We su...

  13. Spiral Countercurrent Chromatography

    Science.gov (United States)

    Ito, Yoichiro; Knight, Martha; Finn, Thomas M.

    2013-01-01

    For many years, high-speed countercurrent chromatography conducted in open tubing coils has been widely used for the separation of natural and synthetic compounds. In this method, the retention of the stationary phase is solely provided by the Archimedean screw effect by rotating the coiled column in the centrifugal force field. However, the system fails to retain enough of the stationary phase for polar solvent systems such as the aqueous–aqueous polymer phase systems. To address this problem, the geometry of the coiled channel was modified to a spiral configuration so that the system could utilize the radially acting centrifugal force. This successfully improved the retention of the stationary phase. Two different types of spiral columns were fabricated: the spiral disk assembly, made by stacking multiple plastic disks with single or four interwoven spiral channels connected in series, and the spiral tube assembly, made by inserting the tetrafluoroethylene tubing into a spiral frame (spiral tube support). The capabilities of these column assemblies were successfully demonstrated by separations of peptides and proteins with polar two-phase solvent systems whose stationary phases had not been well retained in the earlier multilayer coil separation column for high-speed countercurrent chromatography. PMID:23833207

  14. Drift of Spiral Waves in Complex Ginzburg-Landau Equation

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The spontaneous drift of the spiral wave in a finite domain in the complex Ginzburg-Landau equation is investigated numerically. By using the interactions between the spiral wave and its images, we propose a phenomenological theory to explain the observations.

  15. THE STRUCTURE OF NUCLEAR STAR CLUSTERS IN NEARBY LATE-TYPE SPIRAL GALAXIES FROM HUBBLE SPACE TELESCOPE WIDE FIELD CAMERA 3 IMAGING

    Energy Technology Data Exchange (ETDEWEB)

    Carson, Daniel J.; Barth, Aaron J. [Department of Physics and Astronomy, University of California Irvine, 4129 Frederick Reines Hall, Irvine, CA 92697 (United States); Seth, Anil C.; Brok, Mark den [Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112 (United States); Cappellari, Michele [Sub-Department of Astrophysics, Department of Physics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH (United Kingdom); Greene, Jenny E. [Department of Astrophysical Sciences, Princeton University, Peyton Hall—Ivy Lane, Princeton, NJ 08544 (United States); Ho, Luis C. [Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871 (China); Neumayer, Nadine [Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg (Germany)

    2015-05-15

    We obtained Hubble Space Telescope/Wide Field Camera 3 imaging of a sample of ten of the nearest and brightest nuclear clusters (NCs) residing in late-type spiral galaxies, in seven bands that span the near-UV to the near-IR. Structural properties of the clusters were measured by fitting two-dimensional surface brightness profiles to the images using GALFIT. The clusters exhibit a wide range of structural properties, with F814W absolute magnitudes that range from −11.2 to −15.1 mag and F814W effective radii that range from 1.4 to 8.3 pc. For 6 of the 10 clusters in our sample, we find changes in the effective radius with wavelength, suggesting radially varying stellar populations. In four of the objects, the effective radius increases with wavelength, indicating the presence of a younger population that is more concentrated than the bulk of the stars in the cluster. However, we find a general decrease in effective radius with wavelength in two of the objects in our sample, which may indicate extended, circumnuclear star formation. We also find a general trend of increasing roundness of the clusters at longer wavelengths, as well as a correlation between the axis ratios of the NCs and their host galaxies. These observations indicate that blue disks aligned with the host galaxy plane are a common feature of NCs in late-type galaxies, but are difficult to detect in galaxies that are close to face-on. In color–color diagrams spanning the near-UV through the near-IR, most of the clusters lie far from single-burst evolutionary tracks, showing evidence for multi-age populations. Most of the clusters have integrated colors consistent with a mix of an old population (>1 Gyr) and a young population (∼100–300 Myr). The wide wavelength coverage of our data provides a sensitivity to populations with a mix of ages that would not be possible to achieve with imaging in optical bands only. The surface brightness profiles presented in this work will be used for future

  16. The Spiral of Euroscepticism

    DEFF Research Database (Denmark)

    Galpin, Charlotte; Trenz, Hans-Jörg

    2017-01-01

    of Euroscepticism’, taking media autonomy seriously to understand how media logics and selective devices contribute to the shaping of public discourse about the EU. We review the literature on the media and EU legitimacy to show how media frames and their amplification on social media can account for the salience......Media scholars have increasingly examined the effects of a negativity bias that applies to political news. In the ‘spiral of cynicism’, journalist preferences for negative news correspond to public demands for sensational news. We argue that this spiral of cynicism in EU news results in a ‘spiral...

  17. Circularly symmetric light scattering from nanoplasmonic spirals.

    Science.gov (United States)

    Trevino, Jacob; Cao, Hui; Dal Negro, Luca

    2011-05-11

    In this paper, we combine experimental dark-field imaging, scattering, and fluorescence spectroscopy with rigorous electrodynamics calculations in order to investigate light scattering from planar arrays of Au nanoparticles arranged in aperiodic spirals with diffuse, circularly symmetric Fourier space. In particular, by studying the three main types of Vogel's spirals fabricated by electron-beam lithography on quartz substrates, we demonstrate polarization-insensitive planar light diffraction in the visible spectral range. Moreover, by combining dark-field imaging with analytical multiparticle calculations in the framework of the generalized Mie theory, we show that plasmonic spirals support distinctive structural resonances with circular symmetry carrying orbital angular momentum. The engineering of light scattering phenomena in deterministic structures with circular Fourier space provides a novel strategy for the realization of optical devices that fully leverage on enhanced, polarization-insensitive light-matter coupling over planar surfaces, such as thin-film plasmonic solar cells, plasmonic polarization devices, and optical biosensors.

  18. Detection of tibial condylar fractures using 3D imaging with a mobile image amplifier (Siemens ISO-C-3D): Comparison with plain films and spiral CT; Frakturdiagnostik am Kniegelenk mit einem neuen mobilen CT-System (ISO-C-3D): Vergleich mit konventionellem Roentgen und Spiral-CT

    Energy Technology Data Exchange (ETDEWEB)

    Kotsianos, D.; Rock, C.; Wirth, S.; Linsenmaier, U.; Brandl, R.; Fischer, T.; Pfeifer, K.J.; Reiser, M. [Klinikum der Universitaet Muenchen-Innenstadt, Muenchen (Germany). Inst. fuer Klinische Radiologie; Euler, E.; Mutschler, W. [Klinikum der Universitaet Muenchen-Innenstadt, Muenchen (Germany). Chirurgische Klinik und Poliklinik

    2002-01-01

    Purpose: To analyze a prototype mobile C-arm 3D image amplifier in the detection and classification of experimental tibial condylar fractures with multiplanar reconstructions (MPR). Method: Human knee specimens (n=22) with tibial condylar fractures were examined with a prototype C-arm (ISO-C-3D, Siemens AG), plain films (CR) and spiral CT (CT). The motorized C-arm provides fluoroscopic images during a 190 orbital rotation computing a 119 mm data cube. From these 3D data sets MP reconstructions were obtained. All images were evaluated by four independent readers for the detection and assessment of fracture lines. All fractures were classified according to the Mueller AO classification. To confirm the results, the specimens were finally surgically dissected. Results: 97% of the tibial condylar fractures were easily seen and correctly classified according to the Mueller AO classification on MP reconstruction of the ISO-C-3D. There is no significant difference between ISO-C and CT in detection and correct classification of fractures, but ISO-CD-3D is significant by better than CR. (orig.) [German] Zielsetzung: Ziel der vorliegenden Studie war es, die diagnostischen Moeglichkeiten und Grenzen der Erkennbarkeit und Klassifizierung von Frakturen mit multiplanaren Rekonstruktionen (MPR) aus 3D-Datensaetzen eines fahrbaren C-Bogengeraetes an Kniegelenken zu pruefen. Methodik: Kniegelenke von Verstorbenen (n=22) mit Tibiakopffrakturen wurden an einem Prototyp eines mobilen C-Bogen Schnittbild-/Durchleuchtungsgeraets (ISO-C-3D, Siemens AG Erlangen) untersucht. Das Geraet erzeugt waehrend einer einmaligen 190-Grad-Rotation 100 Projektionsaufnahmen, aus denen ein 3D-Volumendatensatz gewonnen wird. Aus diesem werden Hochkontrastschnittbilder als MP-Rekonstruktionen in allen drei Raumebenen errechnet und visualisiert. Die Kniegelenke wurden von 4 unabhaengigen Befundern hinsichtlich Frakturerkennbarkeit, Frakturart und -ausmass unter Verwendung der MP

  19. Identification and characterization of tissues by T2-selective whole-body proton NMR imaging.

    Science.gov (United States)

    Gersonde, K; Tolxdorff, T; Felsberg, L

    1985-08-01

    T2-selective proton imaging at 10 MHz is based on a Carr-Purcell-Meiboom-Gill pulse sequence with at least 36 echoes and 2 tau greater than or equal to 6 ms employing the projection reconstruction technique. The transverse magnetization decay of the volume elements is multiexponential composed of up to three monoexponential T2 components. The T2 values are arranged in T2 histograms which are slice specific. T2 windows are defined in the T2 histogram and used for imaging and for selecting T2 values which are assigned to proton classes and tissues. Tissue characterization is based on the visualization of differences in T2 behavior. The T2 values are transformed into 256 gray levels or, by use of a red-green-blue lookup table, into a rainbow code. Two display techniques have been developed and implemented in the RWTH Aachen Magnetic Resonance Software System (RAMSES): (i) for nonselective T2 imaging with secondary T2 selection and encoding of molecular classes on the basis of T2 values; (ii) for T2-selective imaging by employing combined primary and secondary T2 selection and encoding particular tissues and variations therein. The tissues can be identified by selecting different classes of molecules, like water, lipids, and proteins, when shifting the primary T2 window on the T2 axis of the T2 histogram.

  20. Six Decades of Spiral Density Wave Theory

    Science.gov (United States)

    Shu, Frank H.

    2016-09-01

    The theory of spiral density waves had its origin approximately six decades ago in an attempt to reconcile the winding dilemma of material spiral arms in flattened disk galaxies. We begin with the earliest calculations of linear and nonlinear spiral density waves in disk galaxies, in which the hypothesis of quasi-stationary spiral structure (QSSS) plays a central role. The earliest success was the prediction of the nonlinear compression of the interstellar medium and its embedded magnetic field; the earliest failure, seemingly, was not detecting color gradients associated with the migration of OB stars whose formation is triggered downstream from the spiral shock front. We give the reasons for this apparent failure with an update on the current status of the problem of OB star formation, including its relationship to the feathering substructure of galactic spiral arms. Infrared images can show two-armed, grand design spirals, even when the optical and UV images show flocculent structures. We suggest how the nonlinear response of the interstellar gas, coupled with overlapping subharmonic resonances, might introduce chaotic behavior in the dynamics of the interstellar medium and Population I objects, even though the underlying forces to which they are subject are regular. We then move to a discussion of resonantly forced spiral density waves in a planetary ring and their relationship to the ideas of disk truncation, and the shepherding of narrow rings by satellites orbiting nearby. The back reaction of the rings on the satellites led to the prediction of planet migration in protoplanetary disks, which has had widespread application in the exploding data sets concerning hot Jupiters and extrasolar planetary systems. We then return to the issue of global normal modes in the stellar disk of spiral galaxies and its relationship to the QSSS hypothesis, where the central theoretical concepts involve waves with negative and positive surface densities of energy and angular

  1. Galaxy Zoo: Passive Red Spirals

    CERN Document Server

    Masters, Karen L; Romer, A Kathy; Nichol, Robert C; Bamford, Steven P; Schawinski, Kevin; Lintott, Chris J; Andreescu, Dan; Campbell, Heather C; Crowcroft, Ben; Doyle, Isabelle; Edmondson, Edward M; Murray, Phil; Raddick, M Jordan; Slosar, Anze; Szalay, Alexander S; Vandenberg, Jan

    2009-01-01

    We study the spectroscopic properties and environments of red spiral galaxies found by the Galaxy Zoo project. By carefully selecting face-on, disk dominated spirals we construct a sample of truly passive disks (not dust reddened, nor dominated by old stellar populations in a bulge). As such, our red spirals represent an interesting set of possible transition objects between normal blue spirals and red early types. We use SDSS data to investigate the physical processes which could have turned these objects red without disturbing their morphology. Red spirals prefer intermediate density regimes, however there are no obvious correlations between red spiral properties and environment - environment alone is not sufficient to determine if a galaxy will become a red spiral. Red spirals are a small fraction of spirals at low masses, but dominate at large stellar masses - massive galaxies are red independent of morphology. We confirm that red spirals have older stellar populations and less recent star formation than ...

  2. Planimetry of the aortic valve orifice area: Comparison of multislice spiral computed tomography and magnetic resonance imaging

    Energy Technology Data Exchange (ETDEWEB)

    Westermann, Yvonne; Geigenmueller, Anja; Elgeti, Thomas; Wagner, Moritz [Department of Radiology, Charite - University Medicine, Berlin (Germany); Dushe, Simon [Department of Cardiovascular Surgery, Charite - University Medicine, Berlin (Germany); Borges, Adrian C. [Department of Internal Medicine I - Cardiology, Angiology and Pneumology, Charite - University Medicine, Berlin (Germany); Dohmen, Pascal M. [Department of Cardiovascular Surgery, Charite - University Medicine, Berlin (Germany); Hein, Patrick A. [Department of Radiology, Charite - University Medicine, Berlin (Germany); Lembcke, Alexander, E-mail: Alexander.Lembcke@gmx.de [Department of Radiology, Charite - University Medicine, Berlin (Germany)

    2011-03-15

    Objective: We sought to determine the comparability of multislice computed tomography (MSCT) and magnetic resonance imaging (MRI) for measuring the aortic valve orifice area (AVA) and grading aortic valve stenosis. Materials and methods: Twenty-seven individuals, among them 18 patients with valvular stenosis, underwent AVA planimetry by both MSCT and MRI. In the subset of patients with valvular stenosis, AVA was also calculated from transthoracic Doppler echocardiography (TTE) using the continuity equation. Results: There was excellent correlation between MSCT and MRI (r = 0.99) and limits of agreement were in an acceptable range ({+-}0.42 cm{sup 2}) although MSCT yielded a slightly smaller mean AVA than MRI (1.57 {+-} 0.83 cm{sup 2} vs. 1.67 {+-} 0.98 cm{sup 2}, p < 0.05). However, in the subset of patients with valvular stenosis, the mean AVA was not different between MSCT and MRI (1.05 {+-} 0.30 cm{sup 2} vs. 1.04 {+-} 0.39 cm{sup 2}; p > 0.05). The mean AVAs on both MSCT and MRI were systematically larger than on TTE (0.88 {+-} 0.28 cm{sup 2}, p < 0.001 each). Using an AVA of 1.0 cm{sup 2} on TTE as reference, the best threshold for detecting severe-to-critical stenosis on MSCT and MRI was an AVA of 1.25 cm{sup 2} and 1.30 cm{sup 2}, respectively, resulting in an accuracy of 96% each. Conclusion: Our study specifies recent reports on the suitability of MSCT for quantifying AVA. The data presented here suggest that certain methodical discrepancies of AVA measurements exist between MSCT, MRI and TTE. However, MSCT and MRI have shown excellent correlation in AVA planimetry and similar accuracy in grading aortic valve stenosis.

  3. Triple-Quantum Filtered NMR Imaging of Sodium -23 in the Human Brain

    Science.gov (United States)

    Keltner, John Robinson

    In the past multiple-quantum filtered imaging of biexponential relaxation sodium-23 nuclei in the human brain has been limited by low signal to noise ratios; this thesis demonstrates that such imaging is feasible when using a modified gradient-selected triple-quantum filter at a repetition time which maximizes the signal to noise ratio. Nuclear magnetic resonance imaging of biexponential relaxation sodium-23 (^{23}Na) nuclei in the human brain may be useful for detecting ischemia, cancer, and pathophysiology related to manic-depression. Multiple -quantum filters may be used to selectively image biexponential relaxation ^{23}Na signals since these filters suppress single-exponential relaxation ^{23}Na signals. In this thesis, the typical repetition times (200 -300 ms) used for in vivo multiple-quantum filtered ^{23}Na experiments are shown to be approximately 5 times greater than the optimal repetition time which maximizes multiple-quantum filtered SNR. Calculations and experimental verification show that the gradient-selected triple-quantum (GS3Q) filtered SNR for ^ {23}Na in a 4% agarose gel increases by a factor of two as the repetition time decreases from 300 ms to 55 ms. It is observed that a simple reduction of repetition time also increases spurious single-quantum signals from GS3Q filtered experiments. Irreducible superoperator calculations have been used to design a modified GS3Q filter which more effectively suppresses the spurious single-quantum signals. The modified GS3Q filter includes a preparatory crusher gradient and two-step-phase cycling. Using the modified GS3Q filter and a repetition time of 70 ms, a three dimensional triple-quantum filtered image of a phantom modelling ^{23} Na in the brain was obtained. The phantom consisted of two 4 cm diameter spheres inside of a 8.5 cm x 7 cm ellipsoid. The two spheres contained 0.012 and 0.024 M ^{23}Na in 4% agarose gel. Surrounding the spheres and inside the ellipsoid was 0.03 M aqueous ^{23}Na. The image

  4. Determining the Co-Rotation Radius of Nearby Spiral Galaxies Using Spiral Arm Overlays

    Science.gov (United States)

    Shameer Abdeen, Mohamed; Kennefick, Daniel; Kennefick, Julia D.; Pour Imani, Hamed; Shields, Douglas W.; Eufrasio, Rafael; Berlanga Medina, Jazmin; Monson, Erik

    2017-01-01

    Density wave theory, originally proposed by C.C. Lin and Frank Shu (Lin & Shu 1964), views the spiral arm structures in spiral galaxies as density waves that propagates through the galactic disk. Resonances within orbits create standing wave patterns of density waves that we observe as spiral arms. The theory predicts the existence of a radius known as the co-rotation radius in which the spiral arm pattern speed matches the velocities of the stars within the disk. We introduce a novel way of determining the co-rotation radius, based on an image overlaying technique, which involves tracing the arms of spiral galaxies on images observed from different wavelengths. For the purpose of this study, 12 nearby galaxies were analyzed from four different wavelengths using pitch angle measurements from a previous study (Hamed et al. 2016). We used optical wavelength images (B-Band,440 nm), two infrared wavelength (Infrared; 3.6 µm and 8 µm) Spitzer Space Telescope images and ultraviolet images from GALEX. The results were verified by checking against results compiled from the literature.

  5. Clinical NMR imaging of the brain in children: normal and neurologic disease

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, M.A, (Hammersmith Hospital, London, England); Pennock, J.M.; Bydder, G.M.; Steiner, R.E.; Thomas, D.J.; Hayward, R.; Bryant, D.R.T.; Payne, J.A.; Levene, M.I.; Whitelaw, A.; Dubowitz, L.M.S.; Dubowitz, V.

    1983-11-01

    The results of initial clinical nuclear magnetic resonance imaging of the brain in eight normal and 52 children with a wide variety of neurologic diseases were reviewed. The high level of gray-white matter contrast available with inversion-recovery sequences provided a basis for visualizing normal myelination as well as delays or deficits in this process. The appearances seen in cases of parenchymal hemorrhage, cerebral infarction, and proencephalic cysts are described. Ventricular enlargement was readily identified and marginal edema was demonstrated with spin-echo sequences. Abnormalities were seen in cerebral palsy, congenital malformations, Hallervorden-Spatz disease, aminoaciduria, and meningitis. Space-occupying lesions were identified by virtue of their increased relaxation times and mass effects. Nuclear magnetic resonance imaging has considerable potential in pediatric neuroradiologic practice, in some conditions supplying information not available by computed tomography or sonography.

  6. New and advanced sequences for 23Na NMR imaging, implemented on a 7 T system

    DEFF Research Database (Denmark)

    Laustsen, Christoffer

    2009-01-01

    sodium is excited then it is possible to follow the sodium gradient over time and to determine the cell state earlier than today.   Methods   1. Implementation of multi quantum coherence techniques for sodium pool quantification   2. Development and implementation of the Non Negative Least Square (NNLS......) relaxation analysis for sodium pool quantification   3. Development of novel optimal control quadrupolar coupling band specific excitation experiments   4. Implementation of novel imaging methods for sodium imaging of the "invisible", fast relaxing, sodium pool   5. Implementation of newly proposed...... quadrupolar sodium specific experiments   6. Development of new experiments for sodium quantification purposes   Results   I have shown that it is applicable to use these techniques for in vivo systems on a 7 T experimental scanner. The sodium pool population and the cells under investigation dictate which...

  7. NMR RELAXIVITY AND IMAGING OF NEUTRAL MACROMOLECULAR POLYESTER GADOLINIUM (Ⅲ) COMPLEXES

    Institute of Scientific and Technical Information of China (English)

    Kai-chao Yu; Hong-bing Hu; Mai-li Liu; Han-zhen Yuan; Chao-hui Ye; Ren-xi Zhuo

    1999-01-01

    Five neutral macromolecular polyester gadolinium (Ⅲ) complexes with pendant hydrophobic alkyl and aromatic functional groups were prepared. The longitudinal relaxation rates of these complexes were measured. One of these Gd (Ⅲ) complexes was chosen for the acute toxicity test and T1-weighted imaging measurement. Preliminary results showed that. compared with Gd-DTPA, the neutral macromolecular gadolinium (Ⅲ) complexes provide higher T1 relaxivity enhancement and longer function duration.

  8. The hardening of Portland cement studied by ? NMR stray-field imaging

    Science.gov (United States)

    Nunes, Teresa; Randall, E. W.; Samoilenko, A. A.; Bodart, P.; Feio, G.

    1996-03-01

    Hydration and hardening processes of Portland cement (type I) were studied by analysis of the one-dimensional projections (profiles) obtained periodically with the 0022-3727/29/3/044/img8 stray-field imaging technique over two days. The influence of additives, such as gypsum, in Portland cement (type IA) was also investigated. The decay of the signal intensity as a function of time was found to be bi-exponential for type I and mono-exponential for type IA.

  9. SUPERLUMINOUS SPIRAL GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Ogle, Patrick M.; Lanz, Lauranne; Nader, Cyril; Helou, George, E-mail: ogle@ipac.caltech.edu [IPAC, California Institute of Technology, Mail Code 220-6, Pasadena, CA 91125 (United States)

    2016-02-01

    We report the discovery of spiral galaxies that are as optically luminous as elliptical brightest cluster galaxies, with r-band monochromatic luminosity L{sub r} = 8–14L* (4.3–7.5 × 10{sup 44} erg s{sup −1}). These super spiral galaxies are also giant and massive, with diameter D = 57–134 kpc and stellar mass M{sub stars} = 0.3–3.4 × 10{sup 11}M{sub ⊙}. We find 53 super spirals out of a complete sample of 1616 SDSS galaxies with redshift z < 0.3 and L{sub r} > 8L*. The closest example is found at z = 0.089. We use existing photometry to estimate their stellar masses and star formation rates (SFRs). The SDSS and Wide-field Infrared Survey Explorer colors are consistent with normal star-forming spirals on the blue sequence. However, the extreme masses and rapid SFRs of 5–65 M{sub ⊙} yr{sup −1} place super spirals in a sparsely populated region of parameter space, above the star-forming main sequence of disk galaxies. Super spirals occupy a diverse range of environments, from isolation to cluster centers. We find four super spiral galaxy systems that are late-stage major mergers—a possible clue to their formation. We suggest that super spirals are a remnant population of unquenched, massive disk galaxies. They may eventually become massive lenticular galaxies after they are cut off from their gas supply and their disks fade.

  10. Spiral 2 Week

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2007-07-01

    The main goal of this meeting is to present and discuss the current status of the Spiral-2 project at GANIL in front of a large community of scientists and engineers. Different issues have been tackled particularly the equipment around Spiral-2 like injectors, cryo-modules or beam diagnostics, a workshop was devoted to other facilities dedicated to radioactive ion beam production. This document gathers only the slides of the presentations.

  11. Spiral Shell Collection

    Institute of Scientific and Technical Information of China (English)

    1995-01-01

    In 1988 Zheng Haigen, a seaman with the Towboat Company of the Shanghai Salvage Bureau, began collecting spiral shells. Today he has more than 600 in his collection. The most valuable are the rare parrot shell and a shell whose spirals wind counter-clockwise. In 1991 a miniature conch with a diameter of 0.31 millimeters that he found buried in tons of sand made the Guinness Book of World Records.

  12. Quantitative perfusion imaging by multi-slice CT in stroke patients; Quantitative Perfusionsbildgebung mittels Mehrschicht-Spiral-CT bei Patienten mit akuter zerebraler Ischaemie

    Energy Technology Data Exchange (ETDEWEB)

    Bohner, G.; Klingebiel, R. [Humboldt-Universitaet, Berlin (Germany). Universitaetsklinikum Charite, Abt. Neuroradiologie; Humboldt-Universitaet, Berlin (Germany). Universitaetsklinikum Charite, Inst. fuer Radiologie; Foerschler, A.; Lehmann, R. [Humboldt-Universitaet, Berlin (Germany). Universitaetsklinikum Charite, Abt. Neuroradiologie; Hamm, B. [Humboldt-Universitaet, Berlin (Germany). Universitaetsklinikum Charite, Inst. fuer Radiologie

    2003-06-01

    Objectives: Evaluation of a parametric deconvolution algorithm (DA) in the diagnostic assessment of stroke patients by multislice spiral computed tomography (MS-CT). Material and Methods: 52 patients (age range 34-89 years) with clinically suspected acute ischemia of one hemisphere and no infarct demarcation on plain cerebral CT underwent CT perfusion (CTP), performed on average 3.4 hours after the onset of symptoms by using MS-CT (4 x 8 mm scan volume). Using a DA-based software module, perfusion images of the cerebral blood perfusion (CBP), cerebral blood volume (CBV) and mean transit time (MTT) were calculated and assessed by two readers for visually apparent perfusion abnormalities. Amount and extension of perfusion disturbances were measured and correlated with the outcome. Results: Of 44 patients, in whom perfusion maps could be generated, territorial infarction was confirmed by follow-up in 22 subjects. With a sensitivity of 95% ischemia could be detected on MTT-maps (CBP 91%, CBV 77%). Specificity was highest (100%) for CBV-maps. Patients with infarction showed significant (p<0.001) reduction of CBP (10.7 vs. 38.3 ml/100 ml/min), CBV (1.3 vs. 2.3 ml/100 ml) and prolongation of MTT (12.3 vs. 4.3 s) compared to the contralateral hemisphere, whereas in patients without infarction no significant changes were found. Extension of CBV reduction showed the best correlation (r=0.82) with final infarct volume. Conclusion: The DA-based CTP protocol evaluated in this study is a suitable tool for the early identification and quantification of acute cerebral ischemia. (orig.) [German] Ziel: Evaluation des Einsatzes der Mehrschicht-Spiral-CT (MS-CT) in Kombination mit einem parametrischen Dekonvolutionsalgorithmus (DA) zur zerebralen Perfusionsbildgebung bei Patienten mit klinischen Zeichen einer akuten territorialen Ischaemie. Material und Methoden: 52 Patienten (Altersspanne 34-89 Jahre) mit klinischen Zeichen einer akuten territorialen Ischaemie sowie fehlender

  13. Multiphase imaging of gas flow in a nanoporous material usingremote detection NMR

    Energy Technology Data Exchange (ETDEWEB)

    Harel, Elad; Granwehr, Josef; Seeley, Juliette A.; Pines, Alex

    2005-10-03

    Pore structure and connectivity determine how microstructured materials perform in applications such as catalysis, fluid storage and transport, filtering, or as reactors. We report a model study on silica aerogel using a recently introduced time-of-flight (TOF) magnetic resonance imaging technique to characterize the flow field and elucidate the effects of heterogeneities in the pore structure on gas flow and dispersion with Xe-129 as the gas-phase sensor. The observed chemical shift allows the separate visualization of unrestricted xenon and xenon confined in the pores of the aerogel. The asymmetrical nature of the dispersion pattern alludes to the existence of a stationary and a flow regime in the aerogel. An exchange time constant is determined to characterize the gas transfer between them. As a general methodology, this technique provides new insights into the dynamics of flow in porous media where multiple phases or chemical species may be present.

  14. Effects of Dielectric Substrates and Ground Planes on Resonance Frequency of Archimedean Spirals.

    Science.gov (United States)

    Hooker, Jerris W; Ramaswamy, Vijaykumar; Arora, Rajendra K; Edison, Arthur S; Brey, William W

    2016-04-01

    Superconducting self-resonant spiral structures are of current interest for applications both in metamaterials and as probe coils for nuclear magnetic resonance (NMR) spectroscopy for high-sensitivity chemical analysis. Accurate spiral models are available in the literature for behavior of a spiral below and up to self-resonance. However, knowledge of the higher modes is also important. We present the relationships between the spiral parameters and the multiple mode frequencies of single sided spirals on dielectric substrates as modeled by method of moments simulation. In the absence of a ground plane, we find that the mode frequency has a linear though not necessarily harmonic dependence on the mode number. The effect of a thick substrate can be approximated by an effective dielectric constant. But when the thickness is less than 20% of the spiral trace width (router - rinner) this approximation is no longer accurate. We have developed a simple empirical formula to predict the higher modes.

  15. MEASUREMENT OF GALACTIC LOGARITHMIC SPIRAL ARM PITCH ANGLE USING TWO-DIMENSIONAL FAST FOURIER TRANSFORM DECOMPOSITION

    Energy Technology Data Exchange (ETDEWEB)

    Davis, Benjamin L.; Berrier, Joel C.; Shields, Douglas W.; Kennefick, Julia; Kennefick, Daniel; Seigar, Marc S.; Lacy, Claud H. S. [Arkansas Center for Space and Planetary Sciences, 202 Field House, University of Arkansas, Fayetteville, AR 72701 (United States); Puerari, Ivanio [Instituto Nacional de Astrofisica, Optica y Electronica, Calle Luis Enrique Erro 1, 72840 Santa Maria Tonantzintla, Puebla (Mexico)

    2012-04-01

    A logarithmic spiral is a prominent feature appearing in a majority of observed galaxies. This feature has long been associated with the traditional Hubble classification scheme, but historical quotes of pitch angle of spiral galaxies have been almost exclusively qualitative. We have developed a methodology, utilizing two-dimensional fast Fourier transformations of images of spiral galaxies, in order to isolate and measure the pitch angles of their spiral arms. Our technique provides a quantitative way to measure this morphological feature. This will allow comparison of spiral galaxy pitch angle to other galactic parameters and test spiral arm genesis theories. In this work, we detail our image processing and analysis of spiral galaxy images and discuss the robustness of our analysis techniques.

  16. Measurement of Galactic Logarithmic Spiral Arm Pitch Angle Using Two-Dimensional Fast Fourier Transform Decomposition

    CERN Document Server

    Davis, Benjamin L; Shields, Douglas W; Kennefick, Julia; Kennefick, Daniel; Seigar, Marc S; Lacy, Claud H S; Puerari, Ivânio

    2012-01-01

    A logarithmic spiral is a prominent feature appearing in a majority of observed galaxies. This feature has long been associated with the traditional Hubble classification scheme, but historical quotes of pitch angle of spiral galaxies have been almost exclusively qualitative. We have developed a methodology, utilizing two-dimensional fast Fourier transformations of images of spiral galaxies, in order to isolate and measure the pitch angles of their spiral arms. Our technique provides a quantitative way to measure this morphological feature. This will allow comparison of spiral galaxy pitch angle to other galactic parameters and test spiral arm genesis theories. In this work, we detail our image processing and analysis of spiral galaxy images and discuss the robustness of our analysis techniques.

  17. The role of multislice spiral CT in clinical cardiology

    Energy Technology Data Exchange (ETDEWEB)

    Haberl, R.; Boehme, E.; Richartz, B.; Czernik, A.; Buck, J.; Steinbigler, P. [Medical Hospital I and Department of Radiology, Klinik Muenchen-Pasing, Munich (Germany)

    2004-05-01

    Multislice spiral CT provides diagnostic-quality images of native coronary arteries and bypasses. Indications include prognosis in asymptomatic individuals, detection of significant coronary stenosis, and follow-up after interventions or surgery.

  18. 基于螺旋CT扫描图像的人牙齿的计算机三维重建%Three-dimensional Rebuilding of Human Tooth Based on the Digital Images by Spiral CT

    Institute of Scientific and Technical Information of China (English)

    郭宁山; 冯晓刚; 王乐

    2011-01-01

    目的:研究基于螺旋CT扫描图像的人牙齿的计算机三维重建.方法:采用美国PQ6000型螺旋CT扫描机,自下颌颏部下缘开始至鼻骨底做连续横断超薄扫描,得到了人牙齿的二维CT图像.应用图像处理与识别合成软件,读取二维CT图像数据文件,通过灰度分割方法对二维图像进行边缘提取,再利用三维表面重建算法对所截取的二维CT图像进行三维重建,最终获得人牙齿的三维重建影像.结果:获得的人牙齿三维重建影像,细致逼真、可被任意旋转、剖开、透视、截取,从不同角度观察重建影像形态还原性良好、重建效果满意.结论:基于螺旋CT扫描图像的人牙齿的计算机三维重建,可为有限元实体建模提供快捷、方便的方法.%Objective: To study the rebuilding method of human tooth based on the digital images by spiral CT.Methods: By the PQ6000 spiral CT, successive cross-sectional scanning was made from the inferior edge of the mandibular chin to the bottom of the nasal bone to obtain the two-dimensional digital images.Using the image processing and recognition software,two-dimensional CT image data file was established.Two-dimensional gray image segmentation method was adopted for edge detection.Further, three-dimensional surface reconstruction algorithm was used for the three-dimensional reconstruction by intercepted two-dimensional image.Results: Three-dimensional image of human tooth was obtained, which was rather vivid in every detail, and could be rotated, dissected, perspeeted, and intercepted optionally.It made the observation of images from different angles as possible.The reconstruction showed satisfactory replicating effects.Conclusions: Three-dimensional reconstruction of the human tooth by digital scanning of spiral CT can provide us a convenient and fast method for finite element model establishment.

  19. Metabolic and histopathological alterations of Jatropha mosaic begomovirus-infected Jatropha curcas L. by HR-MAS NMR spectroscopy and magnetic resonance imaging.

    Science.gov (United States)

    Sidhu, O P; Annarao, Sanjay; Pathre, Uday; Snehi, S K; Raj, S K; Roy, Raja; Tuli, Rakesh; Khetrapal, C L

    2010-06-01

    Alterations in the anatomical structures, sap translocation and metabolic profiles in Jatropha curcas L. (Euphorbiaceae), infected with Jatropha mosaic virus (JMV) have been investigated using MRI and HR-MAS NMR spectroscopy. The contrast of MRI images distinguishes abnormalities in anatomical structures of infected and healthy stem. The HR-MAS NMR spectroscopic analysis indicated that viral infection significantly affected the plant metabolism. Higher accumulation of TCA cycle intermediates, such as citrate and malate, in JMV-infected plants suggested a higher rate of respiration. The respiration rate was more than twofold as compared to healthy ones. The viral stress also significantly increases the concentrations of alanine, arginine, glutamine, valine, GABA and choline as compared to healthy ones. Microscopic examination revealed severe hyperplasia caused by JMV with a considerable reduction in the size of stem cells. Lower concentration of glucose and sucrose in viral-infected stem tissues indicates decreased translocation of photosynthates from leaves to stem due to hyperplasia caused by JMV. The MR images distinguished stele, cortical and pith regions of JMV-infected and healthy stems. Contrast of T(1)- and T(2)-weighted images showed significant differences in the spatial distribution of water, lipids and macromolecules in virus-infected and healthy stem tissues. The results demonstrated the value of MRI and HR-MAS NMR spectroscopy in studying viral infection and metabolic shift in plants. The present methodology may help in better understanding the metabolic alterations during biotic stress in other plant species of agricultural and commercial importance.

  20. Comparison of Image Quality and Radiation Dose between High-Pitch Mode and Low-Pitch Mode Spiral Chest CT in Small Uncooperative Children: The Effect of Respiratory Rate.

    Science.gov (United States)

    Kim, Seong Ho; Choi, Young Hun; Cho, Hyun-Hae; Lee, So Mi; Shin, Su-Mi; Cheon, Jung-Eun; Kim, Woo Sun; Kim, In-One

    2016-04-01

    To compare image quality and radiation dose between high-pitch mode (HPM) and low-pitch mode (LPM) CT in young children. Forty-seven children (mean age 35.6 months; range, 0-126 months) underwent 49 CT examinations in HPM or LPM and were divided into high or low respiratory rate (RR) groups. A qualitative image quality was compared between the two modes. The volume CT dose index (CTDIvol) and dose-length product (DLP) were evaluated from the dose reports, and effective doses were assessed using a paediatric phantom. Image quality was generally better for HPM than LPM (diagnostic acceptance score, 4.00 vs. 3.46, P = 0.004); the difference was more prominent in the high RR group (4.00 vs. 3.22, P = 0.001). However, there was no significant difference in the low RR group. The mean DLP value was higher in HPM than LPM (29.48 mGy · cm vs. 23.46 mGy · cm, P = 0.022), while CTDIvol was not significantly different. The total effective radiation dose was 26 % higher in HPM than LPM (1.82 mSv vs. 1.44 mSv). LPM can be considered for paediatric lung evaluation in young children with low RRs to reduce radiation dose while maintaining favourable image quality. • Radiation exposure is higher on high-pitch "Flash spiral mode" than on low-pitch "X-CARE mode". • "Flash spiral mode" generally showed better image quality than "X-CARE mode". • Difference in image quality was more prominent in the high RR group. • There was no difference in image quality in the low RR group. • "X-CARE mode" should be considered in a limited population with low RRs.

  1. Investigating Dwarf Spiral Galaxies

    Science.gov (United States)

    Weerasooriya, Sachithra; Dunn, Jacqueline M.

    2017-01-01

    Several studies have proposed that dwarf elliptical / spheroidal galaxies form through the transformation of dwarf irregular galaxies. Early and late type dwarfs resemble each other in terms of their observed colors and light distributions (each can often be represented by exponential disks), providing reason to propose an evolutionary link between the two types. The existence of dwarf spirals has been largely debated. However, more and more recent studies are using the designation of dwarf spiral to describe their targets of interest. This project seeks to explore where dwarf spirals fit into the above mentioned evolutionary sequence, if at all. Optical colors will be compared between a sample of dwarf irregular, dwarf elliptical, and dwarf spiral galaxies. The dwarf irregular and dwarf elliptical samples have previously been found to overlap in both optical color and surface brightness profile shape when limiting the samples to their fainter members. A preliminary comparison including the dwarf spiral sample will be presented here, along with a comparison of available ultraviolet and near-infrared data. Initial results indicate a potential evolutionary link that merits further investigation.

  2. Diagnosis of traumatic hemarthrosis lipemia by multi-slice spiral CT and magnetic resonance imaging features%创伤性关节积脂血症的多排螺旋CT及磁共振成像诊断

    Institute of Scientific and Technical Information of China (English)

    沈丽荣; 姜兆候; 张立云; 刘永明

    2014-01-01

    Objective To evaluated traumatic hemarthrosis lipemia multi-slice spiral CT and magnetic resonance imaging (MRI) features and diagnostic value. Methods A retrospective analysis of multi-slice spiral CT and MRI features in 23 cases patients with traumatic hemarthrosis hyperlipidemia. All patients were examinated after injury bet-ween one hour to one week by 16-slice spiral CT or MRI, of which 19 cases of knee, hip 4 cases, all patients under-went multi-slice spiral CT, images were transmitted to a workstation for multi-planar reconstruction (MPR), shaded surface display (SSD), volume rendering (VR) and other three-dimensional restructuring, 15 cases of parallel MRI. Results Twenty three patients were joint capsule appeared fat-blood interface sign, including one case of suspected fracture CT, MRI was clear. In 23 patients, a single liquid-liquid plane 17 cases, two liquid-liquid flat 6 cases, liquid-liquid flat top were fat. Conclusion There are characteristic imaging findings of traumatic hemarthrosis lipemia examined by multi-slice spiral CT and MRI , three-dimensional multi-slice spiral CT examination and restructuring can be used as the preferred; MRI is the best imaging method in diagnostic plot lipemia traumatic knee; Plot lipemia can be used as a indirect dia-gnostic signs of intraarticular fractures.%目的:探讨创伤性关节积脂血症的多排螺旋CT及磁共振成像(MRI)影像学特点及诊断价值。方法回顾性分析23例创伤性关节积脂血症患者的多排螺旋CT及MRI影像学特征。所有患者于受伤后1 h至1周内行16排螺旋CT和(或)MRI检查,其中,膝关节19例,髋关节4例,所有患者均行多排螺旋CT检查,图像均传递到工作站进行多平面重组、表面遮盖法、容积再现等三维重建,15例并行MRI检查。结果23例患者关节囊均出现脂肪-血液界面征,其中1例CT可疑骨折,行MRI检查明确诊断。23例患者中,单液-液平面的17

  3. Diagnostic Significance of Lumbar Spine Bone Metastases by 64 Slice Spiral CT and Whole Body Bone Imaging%64层螺旋CT与全身骨显像对腰椎骨转移瘤的诊断意义

    Institute of Scientific and Technical Information of China (English)

    宋世祥

    2014-01-01

    目的:探讨64层螺旋CT与99Tcm-MDP全身骨显像对腰椎骨转移瘤的诊断意义。方法回顾性分析临床确诊腰椎骨转移瘤且资料完整的住院诊治27例患者49处腰椎骨转移瘤,总结分析27例患者的64层螺旋CT与99Tcm-MDP全身骨显像检查结果。比较两种检查结果的灵敏度及特异性。结果经64层螺旋CT检查示,27例患者有41处腰椎锥体破坏;经99Tcm-MDP全身骨显像检查示,23例患者有31处腰椎椎体放射性异常浓集,27例患者发现椎体外多发放射性异常浓集。64层螺旋CT检查的灵敏度为83.6%,特异性为98.6%;99Tcm-MDP全身骨显像检查的灵敏度为63.2%,特异性为96.7%。经64层螺旋CT检查示,有17例明确诊断为腰椎转移瘤,10例可疑为腰椎转移瘤;经99Tcm-MDP全身骨显像检查示,有20例明确诊断为腰椎转移瘤,7例可疑为腰椎转移瘤。结论64层螺旋CT对腰椎骨转移瘤的诊断较99Tcm-MDP全身骨显像具有更高的灵敏度,但多数患者经99Tcm-MDP全身骨显像可获得较为明确的诊断。%Objective To investigate the diagnostic significance of lumbar spine bone metastases by 64 slice spiral CT and 99Tcm-MDP whole body bone imaging. Methods 27 cases of lumbar spine bone metastases with 49 places by clinical diagnosis and with complete hospitalization data were retrospectively analyzed, and the examination results of 27 cases with 64 slice spiral CT and 99Tcm-MDP whole body bone imaging were summarized and analyzed. The sensitivity and specificity of two kinds of examination results were compared. Results The examination result of 64 slice spiral CT showed that 41 vertebrae were damaged in 27 patients, the sensitivity was 83.6%, 17 cases of lumbar spine bone metastases were confirmed by 64 slice spiral CT, 10 patients were suspected. The examination result of 99Tcm-MDP whole body bone imaging showed that 31 vertebrae had radioactive anomaly concentration in 27 patients, the

  4. Embracing the Spiral

    Directory of Open Access Journals (Sweden)

    Li Mao

    2016-12-01

    Full Text Available Critical research demands that we interrogate our own positionality and social location. Critical reflexivity is a form of researcher critical consciousness that is constant and dynamic in a complex spiral-like process starting within our own experiences as racialized, gendered, and classed beings embedded in particular sociopolitical contexts. Across diverse critical methodologies, a group of graduate students and their supervisor explored their own conceptualization of the reflexivity spiral by reflecting on how their research motivations and methodologies emerged from their racializing, colonizing, language-learning, parenting, and identity negotiating experiences. In this article, they present a spiral model of the critical reflexivity process, review the literature on reflexivity, and conclude with a description of critical reflexivity as a social practice within a supportive and collaborative graduate school experience.

  5. 对数螺旋型劳厄弯晶的X射线单色成像应用%Logarithmic Spiral Bent Laue Crystals for X-Ray Monochromatic Imaging Applications

    Institute of Scientific and Technical Information of China (English)

    毋玉芬; 肖沙里; 鲁建; 钱家渝; 刘利锋; 黄显宾

    2013-01-01

    Taking advantages of the monochromatic X-ray diffraction property of Laue crystals,an innovative use of logarithmic spiral bent Laue crystals for X-ray monochromatic imaging is investigated.According to the ray tracing method and the surface equation of the logarithmic spiral,the imaging principles and characteristics of the logarithmic spiral bent Laue crystals are studied,including the condition that the diffracted beam can be separated from the transmitted beam,the magnifications and the field of view (FOV).A logarithmic spiral bent quartz (1010) Laue crystal analyzer is developed.With the proposed crystal analyzer,the monochromatic backlight imaging experiment for the mesh grid with a diameter of 50 μm is carried out by taking an X-ray source of Cu target as the backlighter.The experimental results show that the spatial resolution of the analyzer is approximately 11.9 μm under a source diameter of 110 μm.Furthermore,the FOVs of the crystal analyzer are 22.3557 mm and 8.2602 mm in horizontal and vertical directions,respectively.%利用劳厄晶体研究了X射线的单色衍射性质,研究了对数螺旋型劳厄弯晶在等离子体X射线单色成像中的应用.根据光线追迹原理及对数螺旋线的表面方程,研究了对数螺旋型劳厄弯晶的单色成像原理,分析了单色衍射像不受透射白光X射线影响的准则,以及子午、弧矢放大倍数和单色成像视场等性能参数.研制了石英晶体(1010)对数螺旋劳厄弯晶分析器,以铜靶X射线源作为背光源,对网丝直径为50 μm的金属网格进行了单色背光成像实验.实验结果表明,当背光源尺寸为110 μm时,对数螺旋型劳厄弯晶的空间分辨力约为11.9μm,分析器在子午和弧矢方向的视场分别达到22.3557 mm和8.2602 mm.

  6. Spiral CT arthrography of the knee: technique and value in the assessment of internal derangement of the knee

    Energy Technology Data Exchange (ETDEWEB)

    Berg, Vande B.C.; Lecouvet, F.E.; Maldague, B.; Malghem, J. [Department of Radiology, Cliniques Universitaires St. Luc, Universite Catholique de Louvain, Brussels (Belgium); Poilvache, P. [Department of Orthopedic Surgery, Cliniques Universitaires St. Luc, Universite Catholique de Louvain, Brussels (Belgium)

    2002-07-01

    Computed tomography imaging has achieved excellent multiplanar capability and submillimeter spatial resolution due to the development of the spiral acquisition mode and multidetector row technology. Multidetector spiral CT arthrography (CTA) yields valuable information for the assessment of internal derangement of the joints. This article focuses on the value of spiral CTA of the knee in the assessment of the meniscus, anterior cruciate ligament, and hyaline cartilage lesions. Advantages and disadvantages of spiral CTA with respect to MR imaging are presented. (orig.)

  7. Spirals in protoplanetary disks from photon travel time

    CERN Document Server

    Kama, M; Heays, A N

    2016-01-01

    Spiral structures are a common feature in scattered-light images of protoplanetary disks, and of great interest as possible tracers of the presence of planets. However, other mechanisms have been put foward to explain them, including self-gravity, disk-envelope interactions, and dead zone boundaries. These mechanisms explain many spirals very well, but are unable to easily account for very loosely wound spirals and single spiral arms. We study the effect of light travel time on the shape of a shadow cast by a clump orbiting close (within ${\\sim}1\\,$au) of the central star, where there can be significant orbital motion during the light travel time from the clump to the outer disk and then to the sky plane. This delay in light rays reaching the sky plane gives rise to a variety of spiral- and arc-shaped shadows, which we describe with a general fitting formula for a flared, inclined disk.

  8. Plasmonic response of nanoscale spirals.

    Science.gov (United States)

    Ziegler, Jed I; Haglund, Richard F

    2010-08-11

    The Archimedean spiral geometry presents a platform for exploration of complex plasmonic mechanisms and applications. Here we show both through simulations and experiment that more complex plasmonic modes with unique near-field structure and larger mode volumes can be realized within a single, topologically robust structure. In the spiral, complex polarization response, resonant interactions and symmetry-breaking features are defined by the width and spacing of the spiral tracks and by the winding number of the spiral.

  9. Spiral Antenna-Coupled Microbridge Structures for THz Application.

    Science.gov (United States)

    Gou, Jun; Zhang, Tian; Wang, Jun; Jiang, Yadong

    2017-12-01

    Bolometer sensor is a good candidate for THz imaging due to its compact system, low cost, and wideband operation. Based on infrared microbolometer structures, two kinds of antenna-coupled microbridge structures are proposed with different spiral antennas: spiral antenna on support layer and spiral antenna with extended legs. Aiming at applications in detection and imaging, simulations are carried out mainly for optimized absorption at 2.52 THz, which is the radiation frequency of far-infrared CO2 lasers. The effects of rotation angle, line width, and spacing of the spiral antenna on THz wave absorption of microbridge structures are discussed. Spiral antenna, with extended legs, is a good solution for high absorption rate at low absorption frequency and can be used as electrode lead simultaneously for simplified manufacturing process. A spiral antenna-coupled microbridge structure with an absorption rate of more than 75% at 2.52 THz is achieved by optimizing the structure parameters. This research demonstrates the use of different spiral antennas for enhanced and tunable THz absorption of microbridge structures and provides an effective way to fabricate THz microbolometer detectors with great potential in the application of real-time THz imaging.

  10. Soils, Pores, and NMR

    Science.gov (United States)

    Pohlmeier, Andreas; Haber-Pohlmeier, Sabina; Haber, Agnes; Sucre, Oscar; Stingaciu, Laura; Stapf, Siegfried; Blümich, Bernhard

    2010-05-01

    Within Cluster A, Partial Project A1, the pore space exploration by means of Nuclear Magnetic Resonance (NMR) plays a central role. NMR is especially convenient since it probes directly the state and dynamics of the substance of interest: water. First, NMR is applied as relaxometry, where the degree of saturation but also the pore geometry controls the NMR signature of natural porous systems. Examples are presented where soil samples from the Selhausen, Merzenhausen (silt loams), and Kaldenkirchen (sandy loam) test sites are investigated by means of Fast Field Cycling Relaxometry at different degrees of saturation. From the change of the relaxation time distributions with decreasing water content and by comparison with conventional water retention curves we conclude that the fraction of immobile water is characterized by T1 samples (Haber-Pohlmeier et al. 2010). Third, relaxometric information forms the basis of understanding magnetic resonance imaging (MRI) results. The general difficulty of imaging in soils are the inherent fast T2 relaxation times due to i) the small pore sizes, ii) presence of paramagnetic ions in the solid matrix, and iii) diffusion in internal gradients. The last point is important, since echo times can not set shorter than about 1ms for imaging purposes. The way out is either the usage of low fields for imaging in soils or special ultra-short pulse sequences, which do not create echoes. In this presentation we will give examples on conventional imaging of macropore fluxes in soil cores (Haber-Pohlmeier et al. 2010), and the combination with relaxometric imaging, as well as the advantages and drawbacks of low-field and ultra-fast pulse imaging. Also first results on the imaging of soil columns measured by SIP in Project A3 are given. Haber-Pohlmeier, S., S. Stapf, et al. (2010). "Waterflow Monitored by Tracer Transport in Natural Porous Media Using MRI." Vadose Zone J.: submitted. Haber-Pohlmeier, S., S. Stapf, et al. (2010). "Relaxation in a

  11. Development of phantoms for spiral CT.

    Science.gov (United States)

    Goodenough, D J; Levy, J R; Kasales, C

    1998-01-01

    This paper reports on the development of a new phantom for spiral CT. The phantom meets the increased demands on phantom z-axis uniformity in order that objects from the CT slice, immediately above and below the CT slice of interest, do not contribute perturbing information to the reconstructed CT slice. The phantom depends on formulation of tissue-like materials that can be cast and produced in both geometric and anthropomorphic shapes with sufficient z-axis length to enable unperturbed CT slices of test objects of interest. These materials are then used to produce a series of test objects of CT image quality including low contrast samples that do not require volume averaging or mixing of solutions, and that can reflect sub-slice thickness test objects and supra-slice thickness test objects. The overall phantom and its individual test objects provides meaningful tests of spiral CT image quality including slice sensitivity, CT number linearity and tests of high and low contrast resolution. Schematic designs and actual CT scans are shown. The new spiral phantom appears to meet the increased demands of spiral CT on phantom design, particularly z-axis length, and requirements for low contrast resolution test objects.

  12. Comparison of image quality between axial and spiral scan mode in routine head CT%常规头部CT螺旋扫描与轴扫描模式的影像质量对照

    Institute of Scientific and Technical Information of China (English)

    傅强; 刘晓菲; 于虹; 徐克

    2012-01-01

    目的 通过头部CT螺旋扫描和轴扫描两种不同扫描模式的影像质量对照,探讨常规头部CT采用螺旋扫描模式取代轴扫描模式的可行性.方法 40例患者,其中男性24例,女性16例;年龄18 ~ 74岁,平均年龄46岁.分别接受头部CT螺旋扫描和轴扫描两种不同模式扫描,轴扫描参数:140 kV、170 mA用于颅底部;120 kV、150 mA用于颅脑部,每周2s.螺旋扫描参数:120 kV,150 mA,每周0.6 s.扫描剂量直接取自设备剂量指示值(CTDI和DLP).影像质量分别由2位专家采用双盲法,对头部CT的颅底、脑灰-白质层面及全部影像逐层进行CT值测量评估.结果 常规头部CT螺旋扫描模式较轴扫描模式可有效去除颅底部伪影,并能减少扫描时间和扫描剂量(轴扫描模式与螺旋扫描模式对比,CTDI 55.43 mGy/37.80 mGy;DLP 662.10 mGy· cm/498.28 mGy· cm;扫描时间12.0 s/7.2 s)(P< 0.001).结论 常规头部CT螺旋扫描模式的影像质量完全可与轴扫描模式相媲美,并可取代轴扫描模式.同时常规头部CT螺旋扫描模式还具有可减少扫描时间和辐射剂量,并可进行影像的二维和三维后处理,有利于提高微小病灶正确诊断率的优越性.%Objective To assess the feasibility of replacing axial CT scan mode with spiral CT scan mode in routine head CT through comparing the image quality between spiral and routine axial (sequential) acquired head CT. Methods A total of 40 cases were enrolled, male 24, female 16; aged 18 - 74 years old, mean age 46 years old. They were performed spiral scan and axial scan, respectively. Scan parameter axial mode were 140 kV, 170 mA for petrou bone, and 120 kV, 150 mA for brain, scan time 2.0 s/rol; and spiral mode were 120 kV, 150 mA, scan time 0.6 s/rol. Radiation dose were measured directly from the CT scan indicated computed tomography dose index (CTDI) and dose-length product (DLP). The image quality at the level of the posterior fossa and grey -white matter

  13. Galactic Spiral Structure

    CERN Document Server

    Francis, Charles

    2009-01-01

    We describe the structure and composition of six major stellar streams in a population of 20 574 local stars in the New Hipparcos Reduction with known radial velocities. We find that, once fast moving stars are excluded, almost all stars belong to one of these streams. The results of our investigation have lead us to re-examine the hydrogen maps of the Milky Way, from which we identify the possibility of a symmetric two-armed spiral with half the conventionally accepted pitch angle. We describe a model of spiral arm motions which matches the observed velocities and composition of the six major streams, as well as the observed velocities of the Hyades and Praesepe clusters at the extreme of the Hyades stream. Stellar orbits are perturbed ellipses aligned at a focus in coordinates rotating at the rate of precession of pericentre. Stars join a spiral arm just before apocentre, follow the arm for more than half an orbit, and leave the arm soon after pericentre. Spiral pattern speed equals the mean rate of precess...

  14. Ferroelectricity in spiral magnets

    NARCIS (Netherlands)

    Mostovoy, M

    2006-01-01

    It was recently observed that the ferroelectrics showing the strongest sensitivity to an applied magnetic field are spiral magnets. We present a phenomenological theory of inhomogeneous ferroelectric magnets, which describes their thermodynamics and magnetic field behavior, e.g., dielectric suscepti

  15. Noise reduction of spiral ducts.

    Science.gov (United States)

    Lapka, Wojciech; Cempel, Czesław

    2007-01-01

    The paper presents noise reduction (NR) of spiral ducts as a result of computational modeling of acoustic wave propagation. Three-dimensional models were created with the finite element method in COMSOL Multiphysics version 3.3. Nine models of spiral ducts with 1-9 spiral leads were considered. Time-harmonic analysis was used to predict NR, which was shown in spectral and interval frequency bands. Spiral duct performance can be seen as a comparison of NR before and after a change from a circular to a spiral duct.

  16. Application of NMR spectroscopy and multidimensional imaging to the gelcasting process and in-situ real-time monitoring of cross-linking polyacrylamide gels

    Energy Technology Data Exchange (ETDEWEB)

    Ahuja, S.; Dieckman, S.L.; Gopalsami, N. [and others

    1995-04-01

    In the gelcasting process, a slurry of ceramic powder in a solution of organic monomers is cast in a mold. The process is different from injection molding in that it separates mold-filling from setting during conversion of the ceramic slurry to a formed green part. In this work, NMR spectroscopy and imaging have been conducted for in-situ monitoring of the gelation process and for mapping the polymerization. {sup 1}H nuclear magnetic resonance spectra have been obtained during polymerization of a premix of soluble reactive methacrylamide (monomer) and N, N`-methylene bisacrylamide (cross-linking molecules). The premix was polymerized by adding ammonium persulfate (initiator) and tetramethyl-ethylene-diamine (accelerator) to form long-chain, cross-linked polymers. The time-varying spin-lattice relaxation times T{sub 1} during polymerization have been studied at 25 and 35{degrees}C, and the variation of spectra and T{sub 1} with respect to extent of polymerization has been determined. To verify homogeneous polymerization, multidimensional NMR imaging was utilized for in-situ monitoring of the process. The intensities from the images are modeled and the correspondence shows a direct extraction of T{sub 1} data from the images.

  17. Single-sided NMR

    CERN Document Server

    Casanova, Federico; Blümich, Bernhard

    2011-01-01

    Single-Sided NMR describes the design of the first functioning single-sided tomograph, the related measurement methods, and a number of applications. One of the key advantages to this method is the speed at which the images are obtained.

  18. 多层螺旋CT对胰腺癌的灌注成像研究%Multiple-slice spiral CT perfusion imaging of pancreatic cancer

    Institute of Scientific and Technical Information of China (English)

    程祝忠; 许国辉; 黄娟; 杨宇洁; 曹英; 何韧; 席晓秋

    2008-01-01

    目的 应用MSCT灌注成像技术测量和评价正常胰腺和胰腺癌的血流动力学表现,探讨其在胰腺癌诊断中的临床应用价值.方法 对44例无胰腺疾病患者(正常胰腺患者)、18例胰腺癌患者行MSCT胰腺灌注检查,采用Siemens Bodyperfusion软件测量正常胰腺患者及胰腺癌患者的CT灌注参数值,包括血流量(BF)、血容量(BV)、灌注起始时间(TTS)、峰值到达时间(TTP)、渗透性(permeability)、patlak血流容积(pBV)的平均值,并进行统计学分析.结果 正常胰腺组的BF、BV、TTS、TTP、permeability和pBV分别为:(90.60±29.25)ml·100 ml-1·min-1、(190.35±43.8)ml/L、(205.3±16022)s、(1403.5±334.0)s、(99.47±49.9)05 ml·100ml-1·min-1和(157.8±52.5)ml/L,胰腺癌组的BF、BV、TTS、TTP、permeability和pBV分别为:(22.9±10.63)ml·100 ml-1·min-1、(52.38±18.08)ml/L、(194.3±76.0)s、(1549.5±308.5)s、(115.25±33.55)0.5·100 ml-1·min-1和(83.16±41.45)ml/L.胰腺癌组BF、Bv、pBV明显低于正常组,渗透性高于正常胰腺组,其差异有统计学意义(P0.05).结论 正常胰腺和胰腺癌的CT灌注参数值存在差异,MSCT灌注成像对胰腺癌的诊断有一定的临床价值.%Objective To assess the diagnostic value of multiple-slice spiral CT (MSCT) perfusion imaging technique in pancreatic cancer by measuring and comparing the dynamical characteristics of blood flow between normal pancreas and pancreatic cancer. Methods The CT perfusion imaging were obtained using Siemens Somatoma MSCT scanner in 44 patients with normal pancreas tissue and 18 patients with pancreatic cancer. The mean blood flow (BF),blood volume (BV), time to start (Trs), time to peak (TIP), permeability and patlak blood volume (pBV) were measured and statistically analyzed by using Siemens Body peHusion software package. Results The mean BF, BV, Trs, TIP, permeability and pBV of normal pancreas were: (90.60±29.25) ml·100 ml-1·min-1, (190.35±43.8) ml/L, (205.3±160.2) s, (1403.5

  19. Multi-slice spiral CT three-dimensional imaging and perfusion imaging in acute brain injury of dynamic application%多层螺旋CT三维图像重建和脑灌注成像在急性颅脑损伤动态变化中应用

    Institute of Scientific and Technical Information of China (English)

    杨小秦; 柳少光; 王治民; 王学斌; 张可; 魏晓东; 张冬志

    2012-01-01

    Objective Discussion of ultrathin multilayer spiral CT 3D image reconstruction,skull and brain perfusion imaging in acute brain injury to dynamic changes in the clinical value.Methods 2009December to 2011 October were collected in our hospital in 245 patients with acute traumatic brain injury patients check information,both in the 3-6 h after injury within conventional multislice spiral CT,thin multilayer spiral CT and three-dimensional image reconstruction of skull and brain CT perfusion imaging examination,all the cases in 2 to 7 days after injury dynamic review of conventional MSCT and ultrathin multilayer spiral CT,the data were retrospectively analyzed,using the chi-squared test evaluation.Results Super thin multilayer spiral CT in cerebral contusion and laceration,intracerebral hematoma in TBI with mixed diagnosis has statistics difference is better than the conventional MSCT.CTP in acute traumatic brain injury diagnosis was superior to conventional MSCT except diffuse axonal injury.CTP in cerebral contusion and laceration,subdural hematoma and intracerebral hematoma associated with intracerebral hematoma in the diagnosis with statistical difference,better than the ultrathin multilayer spiral CT (P < 0.05).The 3D image reconstruction of skull fracture demonstrated great advantages in the treatment of skull fracture,which include cranial suture separation and basal skull fracture.Conclusion combined Super thin multilayer spiral CT 3D image reconstruction skull and brain CT perfusion imaging for acute craniocerebral injury early diagnosis and minimal injury diagnosis is superior to conventional multislice spiral CT,The rate of misdiagnosis can be decreased.which provide Reliable basis for early diagnosis and Prognosis of TBI.%目的 探讨超薄多层螺旋CT、颅骨三维图像重建和脑灌注成像在急性颅脑外伤动态变化中的临床应用价值.方法 收集2009年12月至2011年10月我院收治的245例急性颅脑外

  20. Arm Structure in Anemic Spiral Galaxies

    CERN Document Server

    Elmegreen, D M; Frogel, J A; Eskridge, P B; Pogge, R W; Gallagher, A; Iams, J; Elmegreen, Debra Meloy; Elmegreen, Bruce G.; Frogel, Jay A.; Eskridge, Paul B.; Pogge, Richard W.; Gallagher, Andrew; Iams, Joel

    2002-01-01

    Anemic galaxies have less prominent star formation than normal galaxies of the same Hubble type. Previous studies showed they are deficient in total atomic hydrogen but not in molecular hydrogen. Here we compare the combined surface densities of HI and H2 at mid-disk radii with the Kennicutt threshold for star formation. The anemic galaxies are below threshold, which explains their lack of prominent star formation, but they are not much different than other early type galaxies, which also tend to be below threshold. The spiral wave amplitudes of anemic and normal galaxies were also compared, using images in B and J passbands from the OSU Bright Spiral Galaxy Survey. Anemic galaxies have normal spiral wave properties too, with the same amplitudes and radial dependencies as other galaxies of the same arm class. Because of the lack of gas, spiral waves in early type galaxies and anemics do not have a continuous supply of stars with low velocity dispersions to maintain a marginally stable disk. As a result, they ...

  1. Spiral 2 workshop

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2004-07-01

    The accelerator and experimental facilities at GANIL will be transformed over the next 5-10 years. The centerpiece of the additions to the accelerator complex will be Spiral-2. This is the first phase of a new radioactive beam facility based on the ISOL principle. The main aim of Spiral-2 will be to produce intense, high quality beams of neutron-rich nuclei created in neutron-induced fission of heavy elements and accelerated by the existing CIME cyclotron. The principal aims of this workshop will be a) to publicize the new facilities, b) to discuss and define the science which might be carried out with them, c) to discuss the instrumentation and infrastructure required to exploit the new facilities and d) to help form collaborations of scientists wishing to design and construct the equipment needed to undertake the science programme. This document gathers most of the slides presented in the workshop.

  2. Spiral multicapillary columns

    Science.gov (United States)

    Efimenko, A. P.; Naumenko, I. I.; Soboleva, V. K.

    2008-08-01

    It was shown in a theoretical study and confirmed by experiment that a spiral multicapillary column had maximum efficiency if the bunch of capillaries was additionally coiled around its longitudinal axis to produce an integral number of coils. This technique made it possible to manufacture gas-chromatographic columns with performance as high as 12 to 16 thousand theoretical plates. These columns can find various applications, especially if quick separation is required.

  3. Interweaving Chiral Spirals

    CERN Document Server

    Kojo, Toru; Fukushima, Kenji; McLerran, Larry; Pisarski, Robert D

    2011-01-01

    We elaborate how to construct the interweaving chiral spirals in (2+1) dimensions, that is defined as a superposition of differently oriented chiral spirals. We divide the two-dimensional Fermi sea into distinct wedges characterized by the opening angle 2 Theta and the depth Q \\simeq pF, where pF is the Fermi momentum. Each wedge earns an energy gain by forming a single chiral spiral. The optimal values for Theta and Q are chosen by the balance between this energy gain and the energy costs from the deformed Fermi surface (dominant at large Theta) and patch-patch interactions (dominant at small Theta). We estimate these energy gains and costs by means of the expansions in terms of 1/Nc, Lambda_QCD/Q, and Theta using a non-local four-Fermi interaction model: At small 1/Nc the mass gap (chiral condensate) is large enough and the interaction among quarks and the condensate is local in momentum space thanks to the form factor in our non-local model. The fact that patch-patch interactions lie only near the patch bo...

  4. Satellites of spiral galaxies

    Science.gov (United States)

    Zaritsky, Dennis; Smith, Rodney; Frenk, Carlos; White, Simon D. M.

    1993-01-01

    We present a survey of satellites around a homogeneous set of late-type spirals with luminosity similar to that of the Milky Way. On average, we find fewer than 1.5 satellites per primary, but we argue that we can treat the survey as an ensemble and so derive the properties of the halo of a 'typical' isolated spiral. The projected density profile of the ensemble falls off approximately as 1/r. Within 50 kpc the azimuthal distribution of satellites shows some evidence for the 'Holmberg effect', an excess near the minor axis of the primary; however, at larger projected distances, the distribution appears isotropic. There is a weak but significant correlation between the size of a satellite and its distance from its primary, as expected if satellites are tidally truncated. Neither Hubble type nor spectral characteristics correlate with apparent separation. The ensemble of satellites appears to be rotating at about 30 km/s in the same direction as the galactic disk. Satellites on prograde orbits tend to be brighter than those on retrograde orbits. The typical velocity difference between a satellite and its primary shows no clear dependence either on apparent separation, or on the rotation speed of the primary. Thus our survey demonstrates that isolated spiral galaxies have massive halos that extend to many optical radii.

  5. Intermittency in spiral Poiseuille flow

    Energy Technology Data Exchange (ETDEWEB)

    Heise, M; Abshagen, J; Menck, A; Pflster, G [Institute of Experimental and Applied Physics, University of Kiel, 24098 Kiel (Germany)

    2005-01-01

    The results of an experimental study on intermittent spiral vortices observed in a counter-rotating Taylor-Couette system with an additional axial through flow, i.e. Spiral-Poiseuille flow, are presented. Convectively unstable upstream propagating spiral vortices appear in the laminar basic flow from an oscillatory instability and in general become absolutely unstable at higher inner cylinder Reynolds number. It is found that at Reynolds numbers above the absolute stability border the spiral vortices become unstable and a complex flow state showing intermittent bursts appears. The intermittent flow state is characterised by an irregular alternation between clearly distinguishable 'laminar' phases corresponding to up-and downstream propagating spiral vortices as well as propagating Taylor vortices. For a sufficiently high rate of axial through flow it is found that intermittency can occur directly from the convectively unstable regime of the upstream propagating spiral vortices.

  6. Star Formation in Spiral Arms

    CERN Document Server

    Elmegreen, Bruce G

    2011-01-01

    The origin and types of spiral arms are reviewed with an emphasis on the connections between these arms and star formation. Flocculent spiral arms are most likely the result of transient instabilities in the gas that promote dense cloud formation, star formation, and generate turbulence. Long irregular spiral arms are usually initiated by gravitational instabilities in the stars, with the gas contributing to and following these instabilities, and star formation in the gas. Global spiral arms triggered by global perturbations, such as a galaxy interaction, can be wavemodes with wave reflection in the inner regions. They might grow and dominate the disk for several rotations before degenerating into higher-order modes by non-linear effects. Interstellar gas flows through these global arms, and through the more transient stellar spiral arms as well, where it can reach a high density and low shear, thereby promoting self-gravitational instabilities. The result is the formation of giant spiral arm cloud complexes,...

  7. CO Multi-line Imaging of Nearby Galaxies (COMING). I. Physical properties of molecular gas in the barred spiral galaxy NGC 2903

    Science.gov (United States)

    Muraoka, Kazuyuki; Sorai, Kazuo; Kuno, Nario; Nakai, Naomasa; Nakanishi, Hiroyuki; Takeda, Miho; Yanagitani, Kazuki; Kaneko, Hiroyuki; Miyamoto, Yusuke; Kishida, Nozomi; Hatakeyama, Takuya; Umei, Michiko; Tanaka, Takahiro; Tomiyasu, Yuto; Saita, Chey; Ueno, Saeko; Matsumoto, Naoko; Salak, Dragan; Morokuma-Matsui, Kana

    2016-10-01

    We present simultaneous mappings of J = 1-0 emission of 12CO, 13CO, and C18O molecules toward the whole disk (8' × 5' or 20.8 kpc × 13.0 kpc) of the nearby barred spiral galaxy NGC 2903 with the Nobeyama Radio Observatory 45 m telescope at an effective angular resolution of 20″ (or 870 pc). We detected 12CO(J = 1-0) emission over the disk of NGC 2903. In addition, significant 13CO(J = 1-0) emission was found at the center and bar-ends, whereas we could not detect any significant C18O(J = 1-0) emission. In order to improve the signal-to-noise ratio of CO emission and to obtain accurate line ratios of 12CO(J = 2-1)/12CO(J = 1-0) (R2-1/1-0) and 13CO(J = 1-0)/12CO(J = 1-0) (R13/12), we performed the stacking analysis for our 12CO(J = 1-0), 13CO(J = 1-0), and archival 12CO(J = 2-1) spectra with velocity axis alignment in nine representative regions of NGC 2903. We successfully obtained the stacked spectra of the three CO lines, and could measure averaged R2-1/1-0 and R13/12 with high significance for all the regions. We found that both R2-1/1-0 and R13/12 differ according to the regions, which reflects the difference in the physical properties of molecular gas, i.e., density (n_H_2) and kinetic temperature (TK). We determined n_H_2 and TK using R2-1/1-0 and R13/12 based on the large velocity gradient approximation. The derived n_H_2 ranges from ˜1000 cm-3 (in the bar, bar-ends, and spiral arms) to 3700 cm-3 (at the center) and the derived TK ranges from 10 K (in the bar and spiral arms) to 30 K (at the center). We examined the dependence of star formation efficiencies (SFEs) on n_H_2 and TK, and found a positive correlation between SFE and n_H_2 with correlation coefficient for the least-squares power-law fit R2 of 0.50. This suggests that molecular gas density governs the spatial variations in SFEs.

  8. Three-dimensional rebuilding of fixed bridge based on the digital images by spiral CT%基于计算机三维重建技术的固定桥有限元实体建模

    Institute of Scientific and Technical Information of China (English)

    林燕; 冯春霞

    2016-01-01

    目的:研究螺旋CT扫描图像的固定桥计算机三维重建的方法。方法:采用美国PQ6000型螺旋CT扫描机,自下颌颏部下缘开始至鼻骨底做连续横断超薄扫描,得到人牙齿的二维CT图像。应用图像处理与识别合成软件,读取二维CT图像数据文件,通过灰度分割方法对二维图像进行边缘提取,再利用三维表面重建算法对所截取的二维CT图像进行三维重建,最终获得固定桥的三维重建影像。结果:获得了包括牙齿、牙周膜、牙槽骨在内的下颌后牙三单位固定桥的三维有限元数学模型。模型可以根据要求任意进行旋转、缩放、透视、剖开等多种方式观察,并可以按照不同研究目的和要求对模型进行修改和调整。结论:基于螺旋CT扫描图像的固定桥计算机三维重建,可为有限元实体建模提供快捷、方便的方法。%Objective:To study the three dimensional rebuilding method of fixed bridge based on the digital images by spiral CT. Method:By the PQ6000 spiral CT,successive cross-sectional scanning was made from the inferior edge of the mandibular chin to the bottom of the nasal bone to obtain the two-dimensional digital images. Using the image processing and recognition software,two-dimensional CT image data file was established. Two-dimensional gray image segmentation method was adopted for edge detection. Further,three-dimensional surface reconstruction algorithm was used for the three-dimensional reconstruction of the fixed bridge by intercepted two-dimensional image. Result:Three-dimensional image of fixed bridge,including abutment teeth,periodontal membrane and alveolar bone,was obtained,which was rather vivid in every detail,and could be rotated,dissected,perspected,and intercepted optionally. It made the observation of images from different angles as possible. The reconstruction showed satisfactory replicating effects. Conclusion:Three-dimensional reconstruction

  9. Local Spiral Curves Simulating Based on Hough Transformation and Center Auto-Locating of Developing Typhoon

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    In the developing phase of typhoon formation, the spiral belt partly emerges in satellite cloud images. This research starts from images and moves on to graphics and then to representation and recognition. Following this route, local spiral cloud belt is segmented from the raw images using image segmentation, the spiral information is extracted using mathematic morphology, and local spiral curves are detected using Hough transformation. The problem of center locating of developing typhoon has finally been solved through a search algorithm of spiral curve. For No.99082008 cloud image, the result produced by the algorithm in this paper is at 122.3 degree west longitude, 17.5 degree north latitude. The real typhoon center location was at 122.4 degree west longitude, 18 degree north latitude.

  10. Lab-on-a-chip reactor imaging with unprecedented chemical resolution by Hadamard-encoded remote detection NMR.

    Science.gov (United States)

    Telkki, Ville-Veikko; Zhivonitko, Vladimir V; Selent, Anne; Scotti, Gianmario; Leppäniemi, Jarmo; Franssila, Sami; Koptyug, Igor V

    2014-10-13

    The development of microfluidic processes requires information-rich detection methods. Here we introduce the concept of remote detection exchange NMR spectroscopy (RD-EXSY), and show that, along with indirect spatial information extracted from time-of-flight data, it provides unique information about the active regions, reaction pathways, and intermediate products in a lab-on-a-chip reactor. Furthermore, we demonstrate that direct spatial resolution can be added to RD-EXSY efficiently by applying the principles of Hadamard spectroscopy.

  11. Galaxy Zoo: Dust in Spirals

    CERN Document Server

    Masters, Karen L; Bamford, Steven; Mosleh, Moein; Lintott, Chris J; Andreescu, Dan; Edmondson, Edward M; Keel, William C; Murray, Phil; Raddick, M Jordan; Schawinski, Kevin; Slosar, Anze; Szalay, Alexander S; Thomas, Daniel; Vandenberg, Jan

    2010-01-01

    We investigate the effect of dust on spiral galaxies by measuring the inclination-dependence of optical colours for 24,276 well-resolved SDSS galaxies visually classified in Galaxy Zoo. We find clear trends of reddening with inclination which imply a total extinction from face-on to edge-on of 0.7, 0.6, 0.5 and 0.4 magnitudes for the ugri passbands. We split the sample into "bulgy" (early-type) and "disky" (late-type) spirals using the SDSS fracdeV (or f_DeV) parameter and show that the average face-on colour of "bulgy" spirals is redder than the average edge-on colour of "disky" spirals. This shows that the observed optical colour of a spiral galaxy is determined almost equally by the spiral type (via the bulge-disk ratio and stellar populations), and reddening due to dust. We find that both luminosity and spiral type affect the total amount of extinction, with "disky" spirals at M_r ~ -21.5 mags having the most reddening. This decrease of reddening for the most luminous spirals has not been observed before ...

  12. Spiral Microstrip Antenna with Resistance

    Science.gov (United States)

    Shively, David G. (Inventor)

    1998-01-01

    A spiral microstrip antenna having resistor elements embedded in each of the spiral arms is provided. The antenna is constructed using a conductive back plane as a base. The back plane supports a dielectric slab having a thickness between one-sixteenth and one-quarter of an inch. A square spiral, having either two or four arms, is attached to the dielectric slab. Each arm of the spiral has resistor elements thereby dissipating an excess energy not already emitted through radiation. The entire configuration provides a thin, flat, high gain, wide bandwidth antenna which requires no underlying cavity. The configuration allows the antenna to be mounted conformably on an aircraft surface.

  13. Spiral structure in nearby galaxies II. comparative analysis and conclusions

    CERN Document Server

    Kendall, S; Kennicutt, R C

    2014-01-01

    This paper presents a detailed analysis of two-armed spiral structure in a sample of galax- ies from the Spitzer Infrared Nearby Galaxies Survey (SINGS), with particular focus on the relationships between the properties of the spiral pattern in the stellar disc and the global struc- ture and environment of the parent galaxies. Following Paper I we have used a combination of Spitzer Space Telescope mid-infrared imaging and visible multi-colour imaging to isolate the spiral pattern in the underlying stellar discs, and we examine the systematic behaviours of the observed amplitudes and shapes (pitch angles) of these spirals. In general, spiral morphology is found to correlate only weakly at best with morphological parameters such as stellar mass, gas fraction, disc/bulge ratio, and vflat. In contrast to weak correlations with galaxy structure a strong link is found between the strength of the spiral arms and tidal forcing from nearby companion galaxies. This appears to support the longstanding suggestion that ei...

  14. Accuracy, image quality and radiation dose comparison of high-pitch spiral and sequential acquisition on 128-slice dual-source CT angiography in children with congenital heart disease

    Energy Technology Data Exchange (ETDEWEB)

    Nie, Pei; Wang, Ximing; Cheng, Zhaoping; Ji, Xiaopeng; Duan, Yanhua [Shandong University, Shandong Provincial Key Laboratory of Diagnosis and Treatment of Cardio-cerebral Vascular Diseases, Shandong Medical Imaging Research Institute, Jinan, Shandong (China); Chen, Jiuhong [CT Research Collaboration, Siemens Ltd. China, Beijing (China)

    2012-10-15

    To compare accuracy, image quality and radiation dose between high-pitch spiral and sequential modes on 128-slice dual-source computed tomographic (DSCT) angiography in children with congenital heart disease (CHD). Forty patients suspected with CHD underwent 128-slice DSCT angiography with high-pitch mode and sequential mode respectively. All the anomalies were confirmed by the surgical and/or the conventional cardiac angiography (CCA) findings. The diagnostic accuracy, the subjective and objective image quality and effective radiation doses were compared. There was no significant difference in diagnostic accuracy ({chi}{sup 2} = 0.963, P > 0.05), the objective parameters for image quality (P > 0.05) and the image quality of great vessels (u = 167.500, P > 0.05) between the two groups. The image quality of intracardiac structures and coronary arteries was significantly better in the sequential mode group than that in the high-pitch group (u = 112.500 and 100.000, P < 0.05). The mean effective dose in high-pitch group (0.17 {+-} 0.05 mSv) was significantly lower (t = 5.287, P < 0.05) than that in the sequential mode group (0.29 {+-} 0.09 mSv). Both the high-pitch and the sequential modes for 128-slice DSCT angiography provide high accuracy for the assessment of CHD in children, while the high-pitch mode, even with some image quality decrease, further significantly lowers the radiation dose. (orig.)

  15. Quarkyonic Chiral Spirals

    CERN Document Server

    Kojo, Toru; McLerran, Larry; Pisarski, Robert D

    2009-01-01

    We consider the formation of chiral density waves in Quarkyonic matter, which is a phase where cold, dense quarks experience confining forces. We model confinement following Gribov and Zwanziger, taking the gluon propagator, in Coulomb gauge and momentum space, as 1/(p^2)^2. We assume that the number of colors, N, is large, and that the quark chemical potential, mu, is much larger than renormalization mass scale, Lambda_QCD. To leading order in 1/N and Lambda_QCD, a gauge theory with Nf flavors of massless quarks in 3+1 dimensions naturally reduces to a gauge theory in 1+1 dimensions, with an enlarged flavor symmetry of SU(2Nf). Through an anomalous chiral rotation, in two dimensions a Fermi sea of massless quarks maps directly onto the corresponding theory in vacuum. A chiral condensate forms locally, and varies with the spatial position, z, as . Following Schon and Thies, we term this two dimensional pion condensate a (Quarkyonic) chiral spiral. Massive quarks also exhibit chiral spirals, with the magnitude...

  16. Compact orthogonal NMR field sensor

    Science.gov (United States)

    Gerald, II, Rex E.; Rathke, Jerome W [Homer Glen, IL

    2009-02-03

    A Compact Orthogonal Field Sensor for emitting two orthogonal electro-magnetic fields in a common space. More particularly, a replacement inductor for existing NMR (Nuclear Magnetic Resonance) sensors to allow for NMR imaging. The Compact Orthogonal Field Sensor has a conductive coil and a central conductor electrically connected in series. The central conductor is at least partially surrounded by the coil. The coil and central conductor are electrically or electro-magnetically connected to a device having a means for producing or inducing a current through the coil and central conductor. The Compact Orthogonal Field Sensor can be used in NMR imaging applications to determine the position and the associated NMR spectrum of a sample within the electro-magnetic field of the central conductor.

  17. Imaging diagnosis of solitary pulmonary nodules on an open low-field MRI system - comparison of two MR sequences with spiral CT; Bildgebende Diagnostik solitaerer Lungenrundherde am offenen Niederfeld-MRT. Ein Vergleich zweier MR-Sequenzen mit der Spiral-CT

    Energy Technology Data Exchange (ETDEWEB)

    Schaefer, J.F.; Vollmar, J.; Seemann, M.D.; Mehnert, F.; Claussen, C.D. [Abt. fuer Radiologische Diagnostik, Universitaetsklinikum Tuebingen (Germany); Schick, F. [Abt. fuer Radiologische Diagnostik, Sektion Experimentelle Radiologie, Universitaetsklinikum Tuebingen (Germany); Vonthein, R. [Inst. fuer Medizinische Biometrie, Universitaetsklinikum Tuebingen (Germany); Aebert, H. [Abt. fuer Herz-, Thorax- und Gefaesschirurgie, Universitaetsklinikum Tuebingen (Germany)

    2002-09-01

    Objective: To evaluate and compare two fast gradient-echo sequences (GRE) concerning the visualization of solitary pulmonary nodules with an open low-field MRI system in comparison to computed tomography. Materials and Methods: Fourteen patients with solitary pulmonary nodules detected by spiral CT ranging in size from 6 mm to 42 mm (mean 20 mm) underwent MRI on an open 0.2 T scanner using a spoiled 2D GRE (2D FLASH; TR/ TE/Flip = 100 ms/7.5 ms/30 ) and a totally refocused 2D steady-state GRE (True-FISP; TR/TE/FA = 7.3 ms/3.5 ms/80 ). The image quality concerning artifacts (by flow, breathing and susceptibility) and the morphologic characteristics of the nodules were scored and compared with CT by two independent radiologists. The diameters of the nodules measured by MRI were compared with CT measurements. The sequences were also evaluated with regard to the signal-to-noise ratio (SNR) of the lesion. Results: All lesions were detected with the 2D FLASH sequence. True-FISP failed to find a granuloma with a size of 6 mm. The 2D FLASH was rated significantly superior to true FISP concerning image quality artifacts by susceptibility as well as concerning to CT the presentation of nodule characteristics. In MR images, the size of lesions was significantly smaller than in CT images for both sequences: for 2D FLASH the mean difference was 0.9 mm and for true FISP 2.6 mm. The SNR of the nodules was significantly higher for the 2D FLASH than for the true FISP. Conclusion: In low field MRI, the 2D FLASH sequence is superior to the 2D true FISP sequence in imaging of pulmonary nodules. With the 2D FLASH sequence nodules of 6 mm or larger in size can be visualized. (orig.) [German] Zielsetzung: Feststellen der Wertigkeit und Vergleich von zwei schnellen Gradientenechosequenzen (GRE) in der Darstellung solitaerer Lungenrundherde im Vergleich zur Computertomographie am offenen Niederfeld-MR-Tomographen. Material und Methode: 14 Patienten mit einem in der Spiral-CT detektierten

  18. Clinical application of 64-slice spiral computed tomography perfusion imaging technology in kidney disease%64层CT灌注成像技术在肾脏疾病中的应用价值

    Institute of Scientific and Technical Information of China (English)

    唐烨真; 杜涛明; 唐光才; 兰永树; 涂永波; 林伟

    2013-01-01

    Objective: To investigate the clinical application value of 64-slice spiral CT perfusion imaging in kidney diseases diagnosis. Methods: Totally 40 patients met the case criteria, 64-slice spiral CT was used for renal perfusion scan. To observe the sharp of TDC, to records and count BF、BV、MTT and PS of every group. Results: To the same client, the perfusion parameters, index of BF, BV and PS averages and standard deviations of both sides of the kidney had no significant difference (P>0. 05). The BF, BV, MTT and PS among group of renal tumor, cirrhosis, hypertension and control had statistical differences ( P <0. 05). Conclusion: CTPI technologies can evaluate renal function in many aspects, with a promising application prospect.%目的:探讨64层CT灌注扫描技术在肾脏疾病诊断中的临床应用价值.方法:对40例符合入选标准的受检者行双肾灌注扫描,观察TDC形态,记录各组血流量(blood flow,BF)、血容量(blood volume,BV)、平均通过时间(mean transit time,MTT)、表面渗透性(permeability surface,PS)值,并进行统计学分析.结果:同一受检者两侧肾脏BF、BV和PS等参数差异无统计学意义(P>0.05).肾脏肿瘤、肝硬化、高血压及正常组各组间BF、BV及PS差异均有统计学意义(P<0.05).结论:CT灌注成像能从多方面对肾功能进行评价,具有良好的应用前景.

  19. The perfect shape spiral stories

    CERN Document Server

    Hammer, Øyvind

    2016-01-01

    This book uses the spiral shape as a key to a multitude of strange and seemingly disparate stories about art, nature, science, mathematics, and the human endeavour. In a way, the book is itself organized as a spiral, with almost disconnected chapters circling around and closing in on the common theme. A particular strength of the book is its extremely cross-disciplinary nature - everything is fun, and everything is connected! At the same time, the author puts great emphasis on mathematical and scientific correctness, in contrast, perhaps, with some earlier books on spirals. Subjects include the mathematical properties of spirals, sea shells, sun flowers, Greek architecture, air ships, the history of mathematics, spiral galaxies, the anatomy of the human hand, the art of prehistoric Europe, Alfred Hitchcock, and spider webs, to name a few.

  20. CO Multi-line Imaging of Nearby Galaxies (COMING): I. Physical properties of molecular gas in the barred spiral galaxy NGC 2903

    CERN Document Server

    Muraoka, Kazuyuki; Kuno, Nario; Nakai, Naomasa; Nakanishi, Hiroyuki; Takeda, Miho; Yanagitani, Kazuki; Kaneko, Hiroyuki; Miyamoto, Yusuke; Kishida, Nozomi; Hatakeyama, Takuya; Umei, Michiko; Tanaka, Takahiro; Tomiyasu, Yuto; Saita, Chey; Ueno, Saeko; Matsumoto, Naoko; Salak, Dragan; Morokuma, Kana

    2016-01-01

    We present simultaneous mappings of J=1-0 emission of 12CO, 13CO, and C18O molecules toward the whole disk (8' x 5' or 20.8 kpc x 13.0 kpc) of the nearby barred spiral galaxy NGC 2903 with the Nobeyama Radio Observatory 45-m telescope at an effective angular resolution of 20" (or 870 pc). We detected 12CO(J=1-0) emission over the disk of NGC 2903. In addition, significant 13CO(J=1-0) emission was found at the center and bar-ends, whereas we could not detect any significant C18O(J=1-0) emission. In order to improve the signal-to-noise ratio of CO emission and to obtain accurate line ratios of 12CO(J=2-1)/12CO(J=1-0) ($R_{2-1/1-0}$) and 13CO(J=1-0)/12CO(J=1-0) ($R_{13/12}$), we performed the stacking analysis for our 12CO(J=1-0), 13CO(J=1-0), and archival 12CO(J=2-1) spectra with velocity-axis alignment in nine representative regions of NGC 2903. We successfully obtained the stacked spectra of the three CO lines, and could measure averaged $R_{2-1/1-0}$ and $R_{13/12}$ with high significance for all the regions...

  1. NMR GHZ

    CERN Document Server

    Laflamme, R; Zurek, W H; Catasti, P; Mariappan, S V S

    1998-01-01

    We describe the creation of a Greenberger-Horne-Zeilinger (GHZ) state of the form |000>+|111> (three maximally entangled quantum bits) using Nuclear Magnetic Resonance (NMR). We have successfully carried out the experiment using the proton and carbon spins of trichloroethylene, and confirmed the result using state tomography. We have thus extended the space of entangled quantum states explored systematically to three quantum bits, an essential step for quantum computation.

  2. Spiral vane bioreactor

    Science.gov (United States)

    Morrison, Dennis R. (Inventor)

    1991-01-01

    A spiral vane bioreactor of a perfusion type is described in which a vertical chamber, intended for use in a microgravity condition, has a central rotating filter assembly and has flexible membranes disposed to rotate annularly about the filter assembly. The flexible members have end portions disposed angularly with respect to one another. A fluid replenishment medium is input from a closed loop liquid system to a completely liquid filled chamber containing microcarrier beads, cells and a fluid medium. Output of spent medium is to the closed loop. In the closed loop, the output and input parameters are sensed by sensors. A manifold permits recharging of the nutrients and pH adjustment. Oxygen is supplied and carbon dioxide and bubbles are removed and the system is monitored and controlled by a microprocessor.

  3. Spiral microfluidic nanoparticle separators

    Science.gov (United States)

    Bhagat, Ali Asgar S.; Kuntaegowdanahalli, Sathyakumar S.; Dionysiou, Dionysios D.; Papautsky, Ian

    2008-02-01

    Nanoparticles have potential applications in many areas such as consumer products, health care, electronics, energy and other industries. As the use of nanoparticles in manufacturing increases, we anticipate a growing need to detect and measure particles of nanometer scale dimensions in fluids to control emissions of possible toxic nanoparticles. At present most particle separation techniques are based on membrane assisted filtering schemes. Unfortunately their efficiency is limited by the membrane pore size, making them inefficient for separating a wide range of sizes. In this paper, we propose a passive spiral microfluidic geometry for momentum-based particle separations. The proposed design is versatile and is capable of separating particulate mixtures over a wide dynamic range and we expect it will enable a variety of environmental, medical, or manufacturing applications that involve rapid separation of nanoparticles in real-world samples with a wide range of particle components.

  4. Design Consideration and Reconstruction Method for Double-source Double-multislice Spiral CT

    Institute of Scientific and Technical Information of China (English)

    LIU Zun-gang; ZHAO Jun; ZHUANG Tian-ge

    2007-01-01

    To accelerate the scan speed and improve the image quality, a new type of CT configuration, "doublesource double-multislice spiral CT" (DSDMS-CT), which is based on two sets of single-source multislice spiral CT was proposed with a special reconstruction algorithm.Simulation results using the fan-beam filtered backprojection algorithm with a special interpolation method were presented for both single-source multislice spiral CT and DSDMS-CT.The results of new CT model show that it scans faster than the traditional spiral CT and has a better slice sensitivity profile (SSP) with larger pitch value.

  5. Fabrication and characterization of spiral interdigitated electrodes based biosensor for salivary glucose detection

    Science.gov (United States)

    Adelyn, P. Y. P.; Hashim, U.; Arshad, M. K. Md; Voon, C. H.; Liu, Wei-Wen; Kahar, S. M.; Huda, A. R. N.; Lee, H. Cheun

    2017-03-01

    This work introduces the non-invasive glucose monitoring technique by using the Complementary Metal Oxide Semiconductor (CMOS) technologically fabricated spiral Interdigitated Electrodes (IDE) based biosensor. Scanning Electron Microscopy (SEM) image explores the morphology of spiral IDE while Energy Dispersive X-Ray (EDX) determines the elements induced in spiral IDE. Oral saliva of two patients are collected and tested on the spiral IDE sensor with electrical characterization as glucose detection results. However, both patients exhibit their glucose level characteristics inconsistently. Therefore, this work could be extended and enhanced by adding Glutaraldehyde in between 3-Aminoproply)triethoxysilane (APTES) modified and glucose oxidase (GOD) enzyme immobilized layer with FTIR validation for bonding attachment.

  6. Discovery of a low-luminosity spiral DRAGN

    Science.gov (United States)

    Mulcahy, D. D.; Mao, M. Y.; Mitsuishi, I.; Scaife, A. M. M.; Clarke, A. O.; Babazaki, Y.; Kobayashi, H.; Suganuma, R.; Matsumoto, H.; Tawara, Y.

    2016-11-01

    Standard galaxy formation models predict that large-scale double-lobed radio sources, known as DRAGNs, will always be hosted by elliptical galaxies. In spite of this, in recent years a small number of spiral galaxies have also been found to host such sources. These so-called spiral DRAGNs are still extremely rare, with only 5 cases being widely accepted. Here we report on the serendipitous discovery of a new spiral DRAGN in data from the Giant Metrewave Radio Telescope (GMRT) at 322 MHz. The host galaxy, MCG+07-47-10, is a face-on late-type Sbc galaxy with distinctive spiral arms and prominent bulge suggesting a high black hole mass. Using WISE infra-red and GALEX UV data we show that this galaxy has a star formation rate of 0.16-0.75 M⊙ yr-1, and that the radio luminosity is dominated by star-formation. We demonstrate that this spiral DRAGN has similar environmental properties to others of this class, but has a comparatively low radio luminosity of L1.4 GHz = 1.12 × 1022 W Hz-1, two orders of magnitude smaller than other known spiral DRAGNs. We suggest that this may indicate the existence of a previously unknown low-luminosity population of spiral DRAGNS. FITS cutout image of the observed spiral DRAGN MCG+07-47- 10 is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/595/L8

  7. Current State and Progress of Coronary Angiography in Multi-slice Spiral Computed Tomography Imaging Techniques%多排螺旋CT在冠状动脉成像技术中的现状与进展

    Institute of Scientific and Technical Information of China (English)

    胡斌; 徐文坚; 陈海松

    2012-01-01

    多层螺旋CT( mulil slice spiral CT,MSCT)技术的进步为无创性冠状动脉造影提供了广阔的前景,临床应用备受关注.特别是64层CT的出现,空间分辨率、时间分辨率大大提高,心电门控技术及三维后处理技术拓宽了CT在冠状动脉成像中的应用范围.本文阐述了CT在冠状动脉成像技术及影响因素,并对其现状及进展情况作综述.%Multi-detector row CT imaging techniques has great potential for development of noninvasive imaging of the coronary arteries. Coronary CT angiography in clinical utility field was paid highly attention to. Especially current computed tomography (64 slice CT) techniques combine high speed and spatial resolution with electrocardiography synchronization and three-dimensional post processing technology, the scope of coronary CT angiography was widen. This review article will describe the coronary angiography technology of multi-detector row CT and the factors as they relate to the current and future role of coronary CT angiography.

  8. Live imaging of chloroplast FtsZ1 filaments, rings, spirals, and motile dot structures in the AtMinE1 mutant and overexpressor of Arabidopsis thaliana.

    Science.gov (United States)

    Fujiwara, Makoto T; Sekine, Kohsuke; Yamamoto, Yoshiharu Y; Abe, Tomoko; Sato, Naoki; Itoh, Ryuuichi D

    2009-06-01

    Chloroplast division involves the tubulin-related GTPase FtsZ that assembles into a ring structure (Z-ring) at the mid-chloroplast division site, which is where invagination and constriction of the envelope membranes occur. Z-ring assembly is usually confined to the mid-chloroplast site by a well balanced counteraction of the stromal proteins MinD and MinE. The in vivo mechanisms by which FtsZ nucleates at specific sites, polymerises into a protofilament and organizes a closed ring of filament bundles remain largely unknown. To clarify the dynamic aspects of FtsZ, we developed a living cell system for simultaneous visualisation of various FtsZ configurations, utilising the Arabidopsis thaliana overexpressor and mutant of the MinE (AtMinE1) gene, which were modified to weakly express green fluorescent protein (GFP) fused to AtFtsZ1-1. Time-lapse observation in the chloroplasts of both plants revealed disorderly movement of the dots and short filaments of FtsZ. The short filaments often appeared to emanate from the dots and to converge with a long filament, producing a thick cable. In the AtMinE1 overexpressor, we also observed spirals along the longitudinal axis of the organelle that often rolled the closed rings together. In the atminE1 mutant, we visualised the 'isolated' rings with a maximum diameter of approximately 2 mum that did not encircle the organelle periphery, but appeared to be suspended in the stroma. Our observations further demonstrated heterogeneity in chloroplast shapes and concurrently altered configurations of FtsZ in the mutant.

  9. 64排螺旋CT灌注成像对前列腺癌的诊断价值研究%Study on Diagnostic Value of 64 - multidetector Spiral CT Perfusion Imaging in Prostate Carcinoma

    Institute of Scientific and Technical Information of China (English)

    殷少龙; 许庆森; 赵春龙; 武迎军; 冯庆韬

    2012-01-01

    目的 探讨64排螺旋CT灌注成像对前列腺癌(PCa)的诊断价值. 方法 选择2006年8月-2010年5月张家口市第一医院确诊的前列腺癌患者62例,另选择正常前列腺15例为对照组.两组均行64排螺旋CT灌注成像技术检查,对比两组灌注参数之间的差异. 结果 对照组正常前列腺中央带和周围带的CT灌注参数比较,中央带明显高于周围带(P<0.05).正常对照组(周围带)和PCa组的CT灌注参数比较,PCa组的BF、BV、PS明显高于对照组(周围带)(P<0.05),MTT、TTP值明显小于对照组(周围带)(P<0.05).对照组TDC曲线呈缓升-平台型,PCa组TDC曲线呈速升-缓降型. 结论 64排螺旋CT灌注成像对PCa具有重要的诊断价值,其中BF、PS、TTP对PCa的评价意义最大,能更准确反映肿瘤的血管生成,可以作为临床诊断PCa的有效普查方法.%Objective To explore the value of 54 - multidetector spiral CT perfusion imaging in diagnosis of prostate carcinoma (PCa). Methods Sixty- two patients with PCa confirmed by the First Hospital of Zhangjiakou City from August 2006 to May 2010 were selected as PCa group, and another 15 healthy individuals were served as the control group. 64 - multidetector spiral CT perfusion imaging was performed on all objects of the study. The differences in the perfusion parameters of the two groups, including mean blood flow (BF), blood volume (BV), time to peak (TTP), mean transit time (MTT), capillary permeability - surface (PS), time-density curve (TDC) were documented and compared. Results In the control group, the perfusion parameters of the central zone were significantly higher than those in the peripheral zone (P < 0.05). Compared with the perfusion parameters of the peripheral zone of the control group, BF, BV and PS of Pca group were significantly higher than those in the control group (P<0.05), while TTP and MTT were significantly less than those in the control group (P< 0.05). Time - density curve of the

  10. Assessment of perigastric veins anatomy using 64-slice spiral CT angiography with image fusion%64层螺旋CT血管成像及融合技术评价胃周静脉

    Institute of Scientific and Technical Information of China (English)

    李雪华; 孙灿辉; 冯仕庭; 彭振鹏; 何裕隆; 韩方海; 李子平; 孟悛非

    2012-01-01

    To evaluate the efficacy and clinical value of 64-slice spiral CTA with image fusion on the anatomy of perigastric veins. Methods Totally 53 patients underwent abdominal 64-slice spiral CT examination. CTA of perigastric veins, arteries and stomach were reconstructed, and the images were fused with VR technique. The inflow and courses of perigastric veins were observed, as well as the spatial relationship among the perigastric veins, arteries and stomach on CTA. Moreover, the accuracy, sensitivity and specificity of preoperative CTA were detected with surgical findings as standard in 26 patients who underwent gastrectomy. Results In 53 patients, the display rate of the right gastroepiploic vein was 100% (53/53), 90. 57% (48/53) of the left gastric vein, 73. 58% (39/53) of the right gastric vein, 50. 94% (27/53) of the posterior gastric vein, 94. 34% (50/53) of the short gastric vein, 92. 45% (49/53) of the left gastroepiploic vein, and 71. 70% (38/53) of the gastrocolic trunk. The accuracy of preoperative CTA correctly identifying perigastric veins was 92. 31%—100%, the sensitivity was 90. 91%—100%, and the specificity was 100%. Conclusion 64-slice spiral CTA can clearly display perigastric veins and show the relationship among the stomach and perigastric arteries in the living body with the fused image.%目的 探讨64层螺旋CTA及融合技术对胃周静脉的显示能力和临床应用价值.方法 对53例患者行腹部64层螺旋CT扫描.采用VR技术分别重建胃周静脉、动脉和胃,并将其融合,观察胃周静脉的汇入点、走行及其与胃周动脉、胃的空间关系.将26例接受手术治疗患者的术前CTA资料与术中所见进行对比,评价64层螺旋CTA显示胃周静脉的准确率、敏感度及特异度.结果 胃网膜右静脉的显示率为100%(53/53),胃左静脉为90.57%(48/53),胃右静脉为73.58%(39/53)、胃后静脉为50.94%(27/53)、胃短静脉为94.34%(50/53)、胃网膜左静脉为92.45%(49

  11. The Value of Spiral CT Perfusion Imaging in Diagnosis of Adrenal Hyperplasia%螺旋CT灌注成像在肾上腺增生的诊断价值

    Institute of Scientific and Technical Information of China (English)

    袁庆城; 曲雅梅; 张年邱; 赖剑华

    2011-01-01

    Objective: To study the clinical application value of spiral CT perfusion imaging in diagnosis of adrenal hyperplasia. Methods: Spiral CT perfusion imaging was performed in 23 healthy volunteers and 18 patients with adrenal hyperplasia. CT perfusion parameters including relative blood flow (RBF), mean transmit time (MTT) and permeability surface (PS) were analyzed. The test was used in the statistical analysis for the CT perfusion parameters. Results: RBF, MTT and PS of normal adrenal gland were 0.63 ± 0.22 mL/100g/min, 70.65 ± 12.31 s, 0.72 ± 0.13 mL/100g/min respectively. RBF, MTT and PS of adrenal hyperplasia were 0.45 ± 0.19 mL/100g/min, 118.39 ± 19.98 s, 0.49 ±0.21 mL/100g/min respectively. RBV and PS in normal adrenal gland were higher than that of adrenal hyperplasia, while MTT in adrenal hyperplasia was higher than that of normal adrenal gland. There was significant difference of RBF, MTT and PS between normal adrenal gland and adrenal hyperplasia (t = 15.91,20.03, 9.96, respectively, P < 0.05). Conclusion: Spiral CT perfusion imaging is a feasible functional examination for adrenal gland. It reflects the microcirculatory blood flow of adrenal gland and provides useful information for differential diagnosis in adrenal hyperplasia.%目的:研究多层螺旋CT灌注成像在肾上腺增生的诊断价值.方法:对23例正常肾上腺和18例经临床证实的肾上腺增生进行16层螺旋CT灌注成像研究,利用CT灌注软件计算灌注参数,包括相对血流量(RBF)、平均通过时间(MTT)和表面通透性(PS),参数间比较采用t检验.结果:正常肾上腺的RBF、MTT和PS分别为0.63±0.22mL/100g/min、70.65±12.31 s和0.72±0.13mL/100g/min,肾上腺增生RBF、MTT和PS分别为0.45±0.19mL/100g/min、118.39±19.98 s和0.49±0.21mL/100g/min.正常肾上腺的RBF、PS均大于肾上腺增生,肾上腺增生的MTT大于正常肾上腺,其差异有统计学意义(t值分别为15.91、20.03和9.96,P<0.05).结论:肾上腺多层螺

  12. The opacity of spiral galaxy disks. III. Automating the synthetic field method

    NARCIS (Netherlands)

    Holwerda, BW; Gonzalez, RA; Allen, RJ; van der Kruit, PC

    2005-01-01

    Dust extinction in spiral disks can be estimated from the counts of background field galaxies, provided the deleterious effects of confusion introduced by structure in the image of the foreground spiral disk can be calibrated. Gonzalez et al. developed a method for this calibration, the Synthetic Fi

  13. SPIRAL STRUCTURE OF M51 - DISTRIBUTION AND KINEMATICS OF THE ATOMIC AND IONIZED HYDROGEN

    NARCIS (Netherlands)

    TILANUS, RPJ; ALLEN, RJ

    1991-01-01

    The atomic hydrogen (H I) and the H-alpha emission lines in the grand-design spiral galaxy M51 have been observed with the Westerbork Synthesis Radio Telescope and the TAURUS Fabry-Perot imaging spectrometer, respectively. Across the inner spiral arms significant tangential and radial velocity gradi

  14. The Opacity of Spiral Galaxy Disks III : Automating the "Synthetic Field Method"

    NARCIS (Netherlands)

    Holwerda, B. W.; González, R. A.; Allen, R. J.; Kruit, P. C. van der

    2004-01-01

    Abstract: The dust extinction in spiral disks can be estimated from the counts of background field galaxies, provided the deleterious effects of confusion introduced by structure in the image of the foreground spiral disk can be calibrated. Gonzalez et al. (1998) developed a method for this calibrat

  15. Gas and stellar spiral arms and their offsets in the grand-design spiral galaxy M51

    Science.gov (United States)

    Egusa, Fumi; Mentuch Cooper, Erin; Koda, Jin; Baba, Junichi

    2017-02-01

    Theoretical studies on the response of interstellar gas to a gravitational potential disc with a quasi-stationary spiral arm pattern suggest that the gas experiences a sudden compression due to standing shock waves at spiral arms. This mechanism, called a galactic shock wave, predicts that gas spiral arms move from downstream to upstream of stellar arms with increasing radius inside a corotation radius. In order to investigate if this mechanism is at work in the grand-design spiral galaxy M51, we have measured azimuthal offsets between the peaks of stellar mass and gas mass distributions in its two spiral arms. The stellar mass distribution is created by the spatially resolved spectral energy distribution fitting to optical and near-infrared images, while the gas mass distribution is obtained by high-resolution CO and H I data. For the inner region (r ≤ 150 arcsec), we find that one arm is consistent with the galactic shock while the other is not. For the outer region, results are less certain due to the narrower range of offset values, the weakness of stellar arms, and the smaller number of successful offset measurements. The results suggest that the nature of two inner spiral arms is different, which is likely due to an interaction with the companion galaxy.

  16. Effects of Sennae Folium Combined with Mannitol on Multi-slice Spiral CT Bowel Imaging%番泻叶联合甘露醇肠道清洁对多层螺旋CT肠道成像的影响

    Institute of Scientific and Technical Information of China (English)

    项微微; 刘克昌; 殷焱

    2016-01-01

    OBJECTIVE:To evaluate the effects of Sennae Folium combined with mannitol for bowel cleaning on multi-slice spiral CT bowel imaging. METHODS:52 patients receiving multi-slice spiral CT imaging examination in our hospital during Jun. 2011 to Jun. 2012 were collected retrospectively,and then divided into control group(22 cases)and observation group(30 cases) according to the methods of bowel preparation. Both groups fasted for 12 h before examination. Sennae Folium 20 g soaked in boiled water 500 ml for half an hour was given to patients in control group 12 h before examination,and then was soaked in boiled water 500 ml again for drinking and other pure water 1 000 ml was also given to patients. Sennae Folium 10 g soaked in boiled wa-ter 500 ml was given to patients in observation group 1 d before examination and 2 h after breakfast;soaked in boiled water 500 ml again 2 h after lunch;10% mannitol 500 ml and pure water 1 000 ml were given to patients after supper. Both groups received multi-slice spiral CT bowel imaging until the patients defecated watery stool after medication. The effective rate of bowl cleaning, image quality and the incidence of ADR were compared between 2 groups. RESULTS:The effective rate of bowel cleaning was 100% in observation group,which was significantly higher than that of control group(81.82%),with statistical significance(P<0.05). The excellent and good rate of imaging quality was 96.67% in observation group,which was significantly better than that of control group(81.82%),with statistical significance(P<0.05). The incidence of ADR as abdominal distension,nausea,intestinal mucosa damage in observation group were significantly lower than those of control group,with statistical significance (P<0.05). CONCLUSIONS:Sennae Folium combined with mannitol is effective method to prepare enteric multi-slice spiral CT imaging exam-ination,and perform good bowl cleaning effect,high image quality and low incidence of ADR.%目的:评价番泻叶联合

  17. Correlation Study between Spiral CT Perfusion Imaging and Angiogenesis in Esophageal Carcinoma%食管癌螺旋CT灌注成像与肿瘤血管生成的相关性研究

    Institute of Scientific and Technical Information of China (English)

    宋涛; 黎海亮; 窦新民; 吴越; 刘予东

    2011-01-01

    目的 探讨食管癌螺旋CT灌注成像与肿瘤血管生成的相关性.资料与方法 对50例食管癌患者行多排螺旋CT灌注扫描,分析食管癌CT灌注成像参数血容量(BV)、血流量(BF)、平均通过时间(MTT)、表面通透性(PS)与微血管密度(MVD)及血管内皮生长因子(VEGF)表达之间的关系.结果 50例食管癌中,VEGF阳性表达率为62%(31/50),阴性表达率为38%(19/50),MVD值在两组间的差异具有统计学意义(P<0.05);BF值与MVD呈正相关(P<0.05),BV及PS值与MVD呈显著性正相关(P<0.01),MTT值与MVD无相关性(P>0.05);PS值与VEGF表达呈正相关(P<0.05),BF、BV及MTT与VEGF表达无相关性(P>0.05).结论 食管癌CT灌注成像能够在一定程度上反映活体的肿瘤血管生成状况.%Objective To evaluate the correlation between spiral CT perfusion imaging and angiogenesis in esophageal carcinoma. Materials and Methods Multi-detector spiral CT perfusion scan was performed in 50 patients with esophageal carcinoma. The relationship of the CT perfusion imaging parameters, including blood volume ( BV) , blood flow( BF), mean transit time( MTT) ,and permeability surface( PS),with MVD and expressions of VEGF were analyzed. Results In 50 cases,the VEGF positive expression rate was 62% (31/50),and the negative expression rate was 38% ( 19/50). The mean MVD of VEGF-positive group were significantly higher than those of negative group ( P 0.05). The PS value and VEGF expression were positively correlated( P 0.05 ). Conclusion CT perfusion parameters can reflect not only the angiogenesis of esophageal carcinoma of the MVD,but also the expression of VEGF,indicating that CT perfusion parameters can be used as an assessment of tumor angiogenesis in vivo.

  18. The clinical value of multi-slice spiral CT perfusion imaging in diagnosis of thyroid diseases%多层螺旋CT灌注成像在甲状腺疾病诊断中的临床价值

    Institute of Scientific and Technical Information of China (English)

    龚礼春

    2015-01-01

    ObjectiveTo investigate the clinical application value of multi-slice spiral CT perfusion imaging in diagnosis of thyroid diseases.Methods 112 patients with thyroid diseases in our hospital from January 2011 to December 2014 were selected as the research object. All patients with thyroid disease preoperatively received thyroid spiral CT scan, perfusion imaging and color Doppler ultrasonography, diagnosis and comparison of CT and ultrasound results and comparison of application effect in the differential diagnosis of benign and malignant thyroid lesions and imaging characteristics of spiral CT perfusion imaging.ResultsThe operation findings and pathology results was the gold standard, CT group detected thyroid benign lesions in 58 cases, 49 cases of malignant lesions, diagnosis rate was 95.54%, the diagnosis rate was significantly higher than the ultrasound group, and no significant difference compared with pathology results(P>0.05), has no statistical significance; Comparison of benign and malignant thyroid lesions of CT perfusion parameters known, benign and malignant lesions of blood volume (BV) and blood flow (BF) showed no significant difference, but the perfusion time to peak (TTP) and capillary permeability surface (PS) index comparison had the remarkable difference(P<0.05), was statistically significant.Conclusion The sensitivity and specificity for the diagnosis of thyroid diseases with high multi-slice spiral CT perfusion imaging and blood vessels, according to the pathological perfusion parameters and image difference can be accurately distinguish benign and malignant thyroid disease form, has the clinical value of application and popularization.%目的:探讨多层螺旋CT灌注成像在甲状腺疾病诊断中的临床应用价值。方法选取2011年1月~2014年12月我院收治的甲状腺疾病患者112例,作为研究对象。所有患者均以甲状腺疾病拟手术治疗术前进行甲状腺螺旋CT平扫、血管灌注成像及彩色多

  19. On-chip spiral spectrometer

    CERN Document Server

    Redding, Brandon; Bromberg, Yaron; Sarma, Raktim; Cao, Hui

    2016-01-01

    We designed an on-chip spectrometer based on an evanescently-coupled multimode spiral waveguide. Interference between the modes in the waveguide forms a wavelength-dependent speckle pattern which can be used as a fingerprint to identify the input wavelength after calibration. Evanescent coupling between neighboring arms of the spiral enhances the temporal spread of light propagating through the spiral, leading to a dramatic increase in the spectral resolution. Experimentally, we demonstrated that a 250 {\\mu}m radius spiral spectrometer provides a resolution of 0.01 nm at a wavelength of 1520 nm. Spectra containing 40 independent spectral channels can be recovered simultaneously and the operation bandwidth can be increased further when measuring sparse spectra.

  20. Measuring with the spiral reader

    CERN Multimedia

    1974-01-01

    The spiral reader shown here was at the time, together with the Shivamatic scanning system, the basic equipment used for measuring bubble chamber pictures. Anne Anton sits at the table. (See Photo Archive 7408343.)

  1. Discovering Relationships Involving Baravelle Spirals

    Science.gov (United States)

    Wanko, Jeffrey J.

    2006-01-01

    This article details an exploration of Baravelle spirals as visual representations of infinite geometric series, focusing on a variety of strategies used by preservice teachers in discovering patterns and investigating relationships of variables.

  2. Analytical approximations for spiral waves

    Energy Technology Data Exchange (ETDEWEB)

    Löber, Jakob, E-mail: jakob@physik.tu-berlin.de; Engel, Harald [Institut für Theoretische Physik, Technische Universität Berlin, Hardenbergstrasse 36, EW 7-1, 10623 Berlin (Germany)

    2013-12-15

    We propose a non-perturbative attempt to solve the kinematic equations for spiral waves in excitable media. From the eikonal equation for the wave front we derive an implicit analytical relation between rotation frequency Ω and core radius R{sub 0}. For free, rigidly rotating spiral waves our analytical prediction is in good agreement with numerical solutions of the linear eikonal equation not only for very large but also for intermediate and small values of the core radius. An equivalent Ω(R{sub +}) dependence improves the result by Keener and Tyson for spiral waves pinned to a circular defect of radius R{sub +} with Neumann boundaries at the periphery. Simultaneously, analytical approximations for the shape of free and pinned spirals are given. We discuss the reasons why the ansatz fails to correctly describe the dependence of the rotation frequency on the excitability of the medium.

  3. Spiral-shaped disinfection reactors

    KAUST Repository

    Ghaffour, Noreddine

    2015-08-20

    This disclosure includes disinfection reactors and processes for the disinfection of water. Some disinfection reactors include a body that defines an inlet, an outlet, and a spiral flow path between the inlet and the outlet, in which the body is configured to receive water and a disinfectant at the inlet such that the water is exposed to the disinfectant as the water flows through the spiral flow path. Also disclosed are processes for disinfecting water in such disinfection reactors.

  4. Evaluation of spiral CT imaging in the diagnosis of the primary ureteral carcinoma%原发性输尿管癌的螺旋CT表现与病理对照分析

    Institute of Scientific and Technical Information of China (English)

    Xiuli Zhang; Dongmei Guo; Xiyou Zhang; Shen Lv

    2007-01-01

    Objective: To explore the characteristics of the primary ureteral carcinoma (PUC) and discuss the value of spiral CT (SCT) in the diagnosis of PUC. Methods: The SCT findings of the primary ureteral carcinoma in 16 cases were analyzed and compared with the histopathological diagnosis and staging. Results: The transverse diameters of the lesions were1.0-2.1 cm, and the longitudinal lengths were 1.5-15.2 cm. There were no statistically significant differences (P>0.1) in diameters and lengths among the low staging group (pT0-T2) and the high staging group (pT3-T4). The average CT value of the lesions was 43 HU on plain scanning, and 73 HU on CE scanning. The increment was 30 HU. The lesions were clearer on CE scanning. Curved planar reconstruction (CPR) could show the entire course of the urinary tract. Among 6 cases of pT3 stage,CT gave a correct diagnosis in 1 case. For 2 cases of pT4 stage, CT gave correct diagnoses in both cases. Conclusion: The carcinomatous lesions spread along the ureter. The longitudinal length of each lesion is longer than its transverse diameter.Tumor cannot be staged merely according to its diameter and length. CT is difficult to differentiate stage T0-T3, while for stage T4, CT diagnosis is accurate. Contrast enhancement CT scanning has the confirming and differentiating roles. CPR offers direct and easy observing images for clinical doctors.

  5. 武术功力运动对腕骨角结构影响的螺旋CT分析%A spiral CT-image study on the effects of stress induced by Wushu power on carpal angle

    Institute of Scientific and Technical Information of China (English)

    刘鸿宇; 贾素素; 张杰; 陈雁卉; 宋晓霞

    2011-01-01

    Objective To observe the specific structure of carped angle undergoing various exercise stress suchas Wushu by use of the spiral CT. Methods Eight male athletes of Wushu power were selected from the national game, whose skills were to strike off bricks with their hands. There were 12 sports enthusiasts in the control group. All of their hands were scanned by the spiral CT. The two-dimensional images were filtered, screening reduced, enlarged, enhanced, splited, etc. And then the carpal angle was measured. Results The carpal angles were (131.55±7.35)° (right hand) and (133.30±5.68)° (left hand) in the wushu power group, and (136.99±7.22)° (right hand) and (137.38±6.80)° (left hand) in the control. The carpal angle in wushu power was less than that in the control (P < 0.05). Conclusion The stress from the different exercise may induce the different stimuli on the morphology and structure of carpal bones. The Wushu power may lead to a decrease of carpal angle and a contraction of volume and row to human carpal bones.%目的 观测武术功力运动产生的应力对腕骨角结构的影响.方法 选择全国武术功力大赛(单掌断砖项目)男性运动员8人、普通体育运动者12人.用螺旋CT扫描受试者腕骨,对其二维图像进行过滤、筛减、放大、增强、分割等处理,然后测量腕骨角.结果 功力运动员腕骨角为右手(131.55±7.35)°、左手为(133.30±5.68)°;对照组运动员右手为(136.99±7.22)°、左手为(137.38±6.80)°,功力运动员腕骨角小于普通人(P<0.05).结论 不同运动方式对腕骨形态结构产生不同的应力刺激,功力运动可引起腕骨角减小,腕骨体积和排列发生紧缩.

  6. Magnetic fields in spiral galaxies

    Science.gov (United States)

    Beck, Rainer

    2015-12-01

    Radio synchrotron emission, its polarization and Faraday rotation of the polarization angle are powerful tools to study the strength and structure of magnetic fields in galaxies. Unpolarized synchrotron emission traces isotropic turbulent fields which are strongest in spiral arms and bars (20-30 \\upmu G) and in central starburst regions (50-100 \\upmu G). Such fields are dynamically important; they affect gas flows and drive gas inflows in central regions. Polarized emission traces ordered fields, which can be regular or anisotropic turbulent, where the latter originates from isotropic turbulent fields by the action of compression or shear. The strongest ordered fields (10-15 \\upmu G) are generally found in interarm regions. In galaxies with strong density waves, ordered fields are also observed at the inner edges of spiral arms. Ordered fields with spiral patterns exist in grand-design, barred and flocculent galaxies and in central regions. Ordered fields in interacting galaxies have asymmetric distributions and are a tracer of past interactions between galaxies or with the intergalactic medium.—Faraday rotation measures of the diffuse polarized radio emission from galaxy disks reveal large-scale spiral patterns that can be described by the superposition of azimuthal modes; these are signatures of regular fields generated by mean-field dynamos. "Magnetic arms" between gaseous spiral arms may also be products of dynamo action, but need a stable spiral pattern to develop. Helically twisted field loops winding around spiral arms were found in two galaxies so far. Large-scale field reversals, like the one found in the Milky Way, could not yet be detected in external galaxies. In radio halos around edge-on galaxies, ordered magnetic fields with X-shaped patterns are observed. The origin and evolution of cosmic magnetic fields, in particular their first occurrence in young galaxies and their dynamical importance during galaxy evolution, will be studied with

  7. Multi-slice spiral CT perfusion imaging of chronic obstructive pulmonary disease%多层螺旋CT灌注成像对慢性阻塞性肺疾病的诊断价值

    Institute of Scientific and Technical Information of China (English)

    邵燕惠; 钱农; 薛跃君; 戴伊红

    2008-01-01

    目的 研究CT灌注成像对慢性阻塞性肺疾病(COPD)的诊断价值.方法 20例COPD患者和20例志愿者行8层螺旋CT灌注成像,采用电影扫描(cine)方式,层厚5 mm,扫描时间0.5 s/层,注射对比剂后延时5 s,总扫描时间为45 s,测量感兴趣区血流量、血容量、平均通过时间及表面通透性和时间-密度曲线.结果 COPD患者的时间-密度曲线较志愿者曲线平坦,峰值明显降低.COPD患者血流量[(24.77±11.49)ml·min-1·100 g-1]、血容量[(2.48±1.02)ml/100 g]及表面通透性[(2.75±1.13)ml·min-1·100 g-1]明显低于志愿者[血流量(290.14±107.59)ml·min-1·100 g-1、血容量(16.51±5.98)ml/100 g、表面通透性(8.80±3.03)ml·min-1·100 g-1];平均通过时间[(10.58±4.85)s]高于志愿者[(4.50±1.71)s],差异均具有统计学意义(P<0.01).结论 多层螺旋CT肺灌注扫描对COPD的诊断有一定的辅助作用.%Objective To evaluate the diagnostic value of multi-slice spiral CT(MSCT)perfusion imaging in chronic obstructive pulmonary disease(COPD).Methods Twenty COPD patients and20 volunteers underwent 8-row detector spiral CT(MSCT)perfusion imaging using cine scan mode with5 mm slice thickness.0.5 s rotation time and a total scan time of 45 s with 5 s intervals.60 ml contrast agent(300 mg I/ml)were administered at a rate of 4 ml/s from the forearm superficial vein.The imaging data were transferred to a workstation.A time-density curve and pseudo-color map were generated automatically with GE CT perfusion 3 software,the blood flow(BF),blood volume(BV),mean transit time(MTr)and permeability surface(PS)were measured.Results Time-density curve was flatter and the peak of the curve was obviously lower in COPD patients than the volunteers.The BF.BV.PS in COPD volunteers was(10.58 ±4.85)s and(4.50 ±1.71)s respectively.The BF,BV and PS in COPD patients Was lower than the volunteers,the MTY was higher(P<0.01).Conclusion MSCT perfusion imaging is helpful for the diagnosis of COPD.

  8. Most water in the tomato truss is imported through the xylem, not the phloem. An NMR flow imaging study

    NARCIS (Netherlands)

    Windt, C.W.; Gerkema, E.; As, van H.

    2009-01-01

    In this study, we demonstrate nuclear magnetic resonance flow imaging of xylem and phloem transport toward a developing tomato (Solanum lycopersicum) truss. During an 8-week period of growth, we measured phloem and xylem fluxes in the truss stalk, aiming to distinguish the contributions of the two

  9. Morphological structure and water status in tulip bulbs from dormancy to active growth : visualization by NMR imaging

    NARCIS (Netherlands)

    Toorn, van der A.; Zemah, H.; As, van H.; Bendel, P.; Kamenetsky, R.

    2000-01-01

    Magnetic Resonance Imaging (MRI) and light and scanning electron microscopy (SEM) were used to follow time-dependent morphological changes and changes in water status of tulip bulbs (Tulipa gesneriana L., cv. ‘Apeldoorn’) during bulb storage for 12 weeks at 20 °C (non-chilled) or 4 °C (chilled) and

  10. Clinical application of dental panoramic imaging by multi-slice spiral CT%多排螺旋CT全景齿科成像技术的临床价值探讨

    Institute of Scientific and Technical Information of China (English)

    徐刚; 胡海菁; 徐新超; 杜丽云

    2011-01-01

    目的 探讨多排螺旋CT(MSCT)全景齿科成像技术的临床应用价值.方法 对38例患者的牙齿、颌骨部位的容积数据进行后处理,重建出全景齿科图像和牙槽骨的矢状面和冠状曲面图像,与原始图像结合,对牙科疾病进行分析.结果 行MSCT检查的38例口腔疾病患者中,均能全方位立体再现齿科全貌:包括牙冠、牙体、牙根、牙髓腔的局部细节以及牙齿排列及咬合关系,可以从多个角度完整地显示了单个牙体的表面形态、各牙所在的位置、倾斜角度以及各牙之间的距离、牙列的整体形态和牙根的走行方向.结论 多排螺旋CT全景齿科成像可对牙、颌骨内微小病变的诊断治疗提供重要的客观依据,为牙科疾病提供了一种新的先进的检查手段及诊断方法.%Objective To investigate the clinical application of dental panoramic imaging by multi-slice spiral CT (MSCT).Methods Dental panoramic images, coronal and sagittal images of alveolar bone were reconstructed from initial data of tooth and jaw MSCT scanning in 38 patients with oral disease, and the results were compared with original images.Results All these 38 patients accepted MSCT scaning, the panorama of dental could be display clearly, including local details of the crown, dental body, root and pulp cavity, the teeth alignment and occlusal relationship.The surface morphology of each single dental body, the location, inclination angle and distance of each tooth, the dentural integral shape and the root walking direction could be displayed completely.Conclusions As an advanced examinational means and diagnosis method, dental panoramic imaging by MSCT could provide important objective basis?for clinical diagnosis and treatment of minute lesion of the tooth and jaw.

  11. The Effects Analysis of Multi-slice Spiral CT Perfusion Imaging of Different Parts of Normal Pancreas%正常胰腺不同部位的多层螺旋CT灌注成像效果分析

    Institute of Scientific and Technical Information of China (English)

    黄英荷; 杜绪仓

    2013-01-01

    目的:对正常胰腺不同部位的多层螺旋CT灌注成像效果进行分析。方法:抽取行中上腹部CT增强检查而胰腺正常的病例20例作为研究对象,对其胰腺头部、体部以及尾部感兴趣区层面进行CT灌注扫描,对采集的影像数据使用相关灌注软件进行计算,并对灌注参数进行统计学分析。结果:患者正常胰腺的头部、体部以及尾部的灌注参数均无统计学意义,P>0.05。结论:正常胰腺的头部、体部以及尾部的CT灌注参数基本一致。%Objective:To analyze the multi-slice spiral CT perfusion imaging effects of different parts of the normal pancreas Methods:20 patients with normal pancreas were included in this study from January 2010 to December 2011. All Cases underwent contrast-enhanced CT scan and perfusion imaging with pancreatic head,body and tail which included the region of interest (ROI). The perfusion parameters were calculated and statistically analyzed by using the correlational perfusion software. Results:There were not significantly perfusion parameters difference among the head, body and tail of pancreas, P>0.05.Conclusion:The perfusion parameters of normal pancreatici are even consistent.

  12. Supermassive black holes in the Sbc spiral galaxies NGC 3310, NGC 4303 and NGC 4258

    CERN Document Server

    Pastorini, G; Capetti, A; Axon, D J; Alonso-Herrero, A; Atkinson, J; Batcheldor, D; Carollo, C M; Collett, J; Dressel, L; Hughes, M A; Macchetto, D; Maciejewski, W; Sparks, W; van der Marel, R; Pastorini, Guia; Marconi, Alessandro; Capetti, Alessandro; Axon, David J.; Alonso-Herrero, Almudena; Atkinson, John; Batcheldor, Dan; Collett, James; Dressel, Linda; Hughes, Mark A.; Macchetto, Duccio; Maciejewski, Witold; Sparks, William; Marel, Roeland van der

    2007-01-01

    We present new Space Telescope Imaging Spectrograph (STIS) observations of three spiral galaxies, NGC 4303, NGC 3310 and NGC 4258. The bright optical emission lines H$\\alpha$ $\\lambda$ $6564 \\AA$, [NII] $\\lambda

  13. Generation of speckle vortices by Archimedes' spiral micro-holes

    Science.gov (United States)

    Sun, Haibin; Liu, Tingting; Chen, Jun; Sun, Ping

    2016-10-01

    Speckle plays an important role in the optical field. Optical vortices which exist in random speckle fields usually contain useful phase information. The distribution of speckle field is determined by these optical vortices. In order to study speckle vortices quantitatively, we established a micro-holes array model based on the law of Archimedes' spiral arrangement. Speckle vortices can be generated by the random diffuse reflection points (spiral micro-holes). In the experiments, the gray image of Archimedes' spiral micro-holes are displayed on the screen of liquid crystal spatial light modulator (LC-SLM), and the output optical field is captured by a CCD camera. The numerical simulations and experimental results show that the model can be used to generate speckle vortices.

  14. Spirals in protoplanetary disks from photon travel time

    Science.gov (United States)

    Kama, M.; Pinilla, P.; Heays, A. N.

    2016-09-01

    Spiral structures are a common feature in scattered-light images of protoplanetary disks, and of great interest as possible tracers of the presence of planets. However, other mechanisms have been put forward to explain them, including self-gravity, disk-envelope interactions, and dead zone boundaries. These mechanisms explain many spirals very well, but are unable to easily account for very loosely wound spirals and single spiral arms. We study the effect of light travel time on the shape of a shadow cast by a clump orbiting close (within ~ 1 au) of the central star, where there can be significant orbital motion during the light travel time from the clump to the outer disk and then to the sky plane. This delay in light rays reaching the sky plane gives rise to a variety of spiral- and arc-shaped shadows, which we describe with a general fitting formula for a flared, inclined disk. The three movies are available at http://www.aanda.org

  15. Simulations of Normal Spiral Galaxies

    CERN Document Server

    Bottema, R

    2003-01-01

    Results are presented of numerical simulations of normal isolated late type spiral galaxies. Specifically the galaxy NGC 628 is used as a template. The method employs a TREESPH code including stellar particles, gas particles, cooling and heating of the gas, star formation according to a Jeans criterion, and Supernova feedback. A regular spiral disc can be generated as an equilibrium situation of two opposing actions. On the one hand cooling and dissipation of the gas, on the other hand gas heating by the FUV field of young stars and SN mechanical forcing. The disc exhibits small and medium scale spiral structure of which the multiplicity increases as a function of radius. The theory of swing amplification can explain, both qualitatively and quantitatively, the emerging spiral structure. In addition, swing amplification predicts that the existence of a grand design m=2 spiral is only possible if the disc is massive. The simulations show that the galaxy is then unstable to bar formation. A general criterion is ...

  16. Orientation decoding: Sense in spirals?

    Science.gov (United States)

    Clifford, Colin W G; Mannion, Damien J

    2015-04-15

    The orientation of a visual stimulus can be successfully decoded from the multivariate pattern of fMRI activity in human visual cortex. Whether this capacity requires coarse-scale orientation biases is controversial. We and others have advocated the use of spiral stimuli to eliminate a potential coarse-scale bias-the radial bias toward local orientations that are collinear with the centre of gaze-and hence narrow down the potential coarse-scale biases that could contribute to orientation decoding. The usefulness of this strategy is challenged by the computational simulations of Carlson (2014), who reported the ability to successfully decode spirals of opposite sense (opening clockwise or counter-clockwise) from the pooled output of purportedly unbiased orientation filters. Here, we elaborate the mathematical relationship between spirals of opposite sense to confirm that they cannot be discriminated on the basis of the pooled output of unbiased or radially biased orientation filters. We then demonstrate that Carlson's (2014) reported decoding ability is consistent with the presence of inadvertent biases in the set of orientation filters; biases introduced by their digital implementation and unrelated to the brain's processing of orientation. These analyses demonstrate that spirals must be processed with an orientation bias other than the radial bias for successful decoding of spiral sense.

  17. 肺癌特异血管征象的64层CT首过期灌注增强表达%Expressing the specific vessels signs in lung cancer by 64-slice spiral CT in first phase perfusion imaging *

    Institute of Scientific and Technical Information of China (English)

    苏冠琴; 薄晓庆; 杨署; 孙国鹏; 柴军; 周苛; 高阿枚; 段呼兵; 董秀萍

    2013-01-01

    Objective To investigate the specific vessels signs in lung cancer by 64-slice spiral CT in first phase perfusion ima-ging so as to get more reasonable time about CT angiography .Methods Among the 47 cases ,there were 38 cases of central and 9 cases of peripheral primary lung cancer underwent 64-slice spiral CT in first phase perfusion imaging :one scan was obtained every 1 seconds during 8-38 seconds with 8 section × I without scanning interval after injection .Precontrast and postcontrast attenuation on every leisions was recorded ,to calculate the peak height(PH) and peak height time by time density curves TDC of pulmonary le-sions to aorta ,those reflect the the tumor feeding artery Imaging about lesions of lung cancer and inflammation .observed and calcu-lated the display rate and display time of lesions of lung cancer and inflammation .means of t test was used for statistics .Results a-bout the peak heights of in pulmonary artery and aorta phese ,statistically significant differences were found between inflammation and lung cancer(P0 .05) . about the peak heights time in aorta phase ,no statistically significant differences were found among three groups (P>0 .05) .The tumor vascularity were discoved in lesions in patients with lung cancer (44/47 cases ,93 .62% );The erosion narrow pulmonary ar-tery were discoved in central lung cancer (37/38 cases ,97 .37% ) ,in peripheral lung cancer(6/9 cases 66 .67% );no abnormal pulmo-nary artery were discoved only in 4 patients with lung cancer .Both tumor vascularity and abnormal pulmonary artery were most dis-plaied in 18-31s in CT angiography .Conclusion 64-slice spiral CT in first phase dynamic perfusion imaging can order completely show the specific vessels signs in lung cancer and reflect the tumor feeding artery Imaging of lung cancer .Analysising those benefi-ted to select reasonably the time of CT angiography and Improve the rate of lung cancer diagnosis .%目的分析64层C T首过期灌注增强对肺癌特

  18. A Chandra Observation of the Face-on Spiral Galaxy NGC 3938

    Science.gov (United States)

    Buhidar, Kelsey; Schlegel, Eric M.

    2017-01-01

    The ACIS detector (Advanced CCD Imaging Spectrometer) onboard the Chandra X-ray Observatory has imaged the face-on spiral NGC 3938 for 50 ksec. We will detect ~50 sources within the D25 radius. We will describe the luminosity distribution in comparison with distributions from other nearby spiral galaxies. We do not detect any diffuse emission. We will compare the X-ray data to observations at other wavebands.

  19. Reconstruction of the portal vein with 64-slice spiral CT of bile duct obstruction

    OpenAIRE

    Xia, Yunbao; PAN, GONGMAO; Xue, Feng; Geng, Chengjun

    2013-01-01

    The aim of this study was to evaluate 64-slice spiral CT image reconstruction of the portal vein in biliary obstruction. A total of 34 clinical patients with biliary obstruction were confirmed by 64-slice spiral CT scanning with portal venous phase multi-planar reconstruction (MPR) of the biliary tract, curved planar reconstruction (CPR), thin-slab minimum-intensity projection (TS-MinIP) and maximum intensity projection (MIP). The reconstructed images were reviewed to further assess the posit...

  20. Gas and stellar spiral arms and their offsets in the grand-design spiral galaxy M51

    CERN Document Server

    Egusa, Fumi; Koda, Jin; Baba, Junichi

    2016-01-01

    Theoretical studies on the response of interstellar gas to a gravitational potential disc with a quasi-stationary spiral arm pattern suggest that the gas experiences a sudden compression due to standing shock waves at spiral arms. This mechanism, called a galactic shock wave, predicts that gas spiral arms move from downstream to upstream of stellar arms with increasing radius inside a corotation radius. In order to investigate if this mechanism is at work in the grand-design spiral galaxy M51, we have measured azimuthal offsets between the peaks of stellar mass and gas mass distributions in its two spiral arms. The stellar mass distribution is created by the spatially resolved spectral energy distribution fitting to optical and near infrared images, while the gas mass distribution is obtained by high-resolution CO and HI data. For the inner region (r < 150"), we find that one arm is consistent with the galactic shock while the other is not. For the outer region, results are less certain due to the narrower...

  1. Spiral Inflector For Compact Cyclotron

    CERN Document Server

    Karamysheva, G A

    2004-01-01

    Compact cyclotron for explosives detection by nuclear resonance absorption of γ-rays in nitrogen is under development [1] Cyclotron will be equipped with the external ion source. The injection system consists of a double-drift beam bunching system, a spiral inflector, beam diagnostics, focusing and adjustment elements [2]. The spiral inflector for ion bending from axial to median plane is used. Computer model of spiral inflector for the Customs cyclotron is developed. 3D electrostatic field calculations of the designed inflector are performed. Calculated electric field map and magnetic field map of the cyclotron [3] are used for beam dynamic simulations. Numeric simulations are carried out for 500 particles using code for calculation of particle dynamics by integration of differential equations in Cartesian coordinate system written in MATLAB. Direct Coulomb particle-to-particle method is used to take into account space-charge effects.

  2. Transient spirals as superposed instabilities

    CERN Document Server

    Sellwood, J A

    2014-01-01

    We present evidence that recurrent spiral activity, long manifested in simulations of disk galaxies, results from the super-position of a few transient spiral modes. Each mode lasts between five and ten rotations at its corotation radius where its amplitude is greatest. The scattering of stars as each wave decays takes place over narrow ranges of angular momentum, causing abrupt changes to the impedance of the disk to subsequent traveling waves. Partial reflections of waves at these newly created features, allows new standing-wave instabilities to appear that saturate and decay in their turn, scattering particles at new locations, creating a recurring cycle. The spiral activity causes the general level of random motion to rise, gradually decreasing the ability of the disk to support further activity unless the disk contains a dissipative gas component from which stars form on near-circular orbits. We also show that this interpretation is consistent with the behavior reported in other recent simulations with l...

  3. Magnetic Fields in Spiral Galaxies

    CERN Document Server

    Beck, Rainer

    2015-01-01

    Radio synchrotron emission is a powerful tool to study the strength and structure of magnetic fields in galaxies. Unpolarized synchrotron emission traces isotropic turbulent fields which are strongest in spiral arms and bars (20-30\\mu G) and in central starburst regions (50-100\\mu G). Such fields are dynamically important; they affect gas flows and drive gas inflows in central regions. Polarized emission traces ordered fields, which can be regular or anisotropic turbulent, where the latter originates from isotropic turbulent fields by the action of compression or shear. The strongest ordered fields (10-15\\mu G) are generally found in interarm regions. In galaxies with strong density waves, ordered fields are also observed at the inner edges of spiral arms. Ordered fields with spiral patterns exist in grand-design, barred and flocculent galaxies, and in central regions. Ordered fields in interacting galaxies have asymmetric distributions and are a tracer of past interactions between galaxies or with the interg...

  4. Brucellar spondylitis: evaluation by NMR imaging, CT and biomedical radiography - a case report; Espondilite por brucelose - relato de um caso

    Energy Technology Data Exchange (ETDEWEB)

    Campos, Juliana C. de; Marins, Jose Luiz C.; Pereira, Rubens Marcondes [Centro Radiologico, Campinas, SP (Brazil)

    1999-03-01

    A 50-year-old white woman presented with a 4-month history of low pain with lower extremity irradiation. Image studies showed inflammatory changes of the vertebral bodies and invertebral disk at L3-L4 level. Considering she had no previous spinal surgery, negative tests for tuberculosis and a positive history of exposure to brucellosis, further studies were done, and the serologic tests were positive for brucellar antibodies. Follow-up studies within the first two months demonstrated the progressive spinal changes in brucellar spondylitis. (author)

  5. Pulmonary embolism findings on chest radiographs and multislice spiral CT

    Energy Technology Data Exchange (ETDEWEB)

    Coche, Emmanuel; Goncette, Louis [Department of Radiology, Cliniques Universitaires Saint-Luc, Universite Catholique de Louvain, Avenue Hippocrate 10, 1200, Brussels (Belgium); Verschuren, Franck [Department of Intensive Care and Emergency Medicine, Cliniques Universitaires Saint-Luc, Universite Catholique de Louvain, Avenue Hippocrate 10, 1200, Brussels (Belgium); Hainaut, Philippe [Department of Internal Medicine, Cliniques Universitaires Saint-Luc, Universite Catholique de Louvain, Avenue Hippocrate 10, 1200, Brussels (Belgium)

    2004-07-01

    Multislice spiral CT is becoming an increasingly important tool for diagnosing pulmonary embolism. However, in many instances, a chest radiograph is usually performed as a first-line examination. Many parenchymal, vascular, and other ancillary findings may be observed on both imaging modalities with a highly detailed depiction of abnormalities on multislice CT. A comprehensive review of chest radiograph findings is presented with side-by-side correlations of CT images reformatted mainly in the frontal plane. (orig.)

  6. Pulmonary embolism findings on chest radiographs and multislice spiral CT.

    Science.gov (United States)

    Coche, Emmanuel; Verschuren, Franck; Hainaut, Philippe; Goncette, Louis

    2004-07-01

    Multislice spiral CT is becoming an increasingly important tool for diagnosing pulmonary embolism. However, in many instances, a chest radiograph is usually performed as a first-line examination. Many parenchymal, vascular, and other ancillary findings may be observed on both imaging modalities with a highly detailed depiction of abnormalities on multislice CT. A comprehensive review of chest radiograph findings is presented with side-by-side correlations of CT images reformatted mainly in the frontal plane.

  7. Digital spiral object identification using random light

    CERN Document Server

    Yang, Zhe; Mirhosseini, Mohammad; Zhou, Yiyu; Gao, Boshen; Gao, Lu; Rafsanjani, Seyed Mohammad Hashemi; Long, Guilu; Boyd, Robert W

    2016-01-01

    Photons that are entangled or correlated in orbital angular momentum have been extensively used for remote sensing, object identification and imaging. It has recently been demonstrated that intensity fluctuations give rise to the formation of correlations in the orbital angular momentum components and angular positions of random light. Here, we demonstrate that the spatial signatures and phase information of an object, with rotational symmetries, can be identified using classical orbital angular momentum correlations in random light. The Fourier components imprinted in the digital spiral spectrum of the object, measured through intensity correlations, unveil its spatial and phase information. Sharing similarities with conventional compressive sensing protocols that exploit sparsity to reduce the number of measurements required to reconstruct a signal, our technique allows sensing of an object with fewer measurements than other schemes that use pixel-by-pixel imaging. One remarkable advantage of our technique ...

  8. 64层螺旋CT灌注成像在乳腺疾病诊断中的应用研究%APPLICATION OF 64-SLICE SPIRAL CT PERFUSION IMAGING IN THE DIAGNOSIS OF BREAST DISEASES

    Institute of Scientific and Technical Information of China (English)

    曾勇; 吴垦; 黎学刚

    2011-01-01

    [目的]进行64层螺旋CT灌注成像研究,探讨该技术在乳腺疾病诊断中的应用前景.[方法]选择于2008年5月~2009年5月期间临床检查或钼靶检查怀疑有乳腺疾病的61例女性患者行CT灌注扫描.按照病理将其分为3组:增生病组(n= 14)、纤维腺瘤组(n=19)和乳腺癌组(n=20),并将所有患者对侧乳腺定为正常组(n=61).进行灌注序列body perfusion扫描及Perfusion 3体部灌注软件处理,计算感兴趣区的血流动力学参数血流量(BF)、平均通过时间、血容量(BV)(MTT)和表面通透性(PS),统计分析不同组间的测量值.[结果]与乳腺癌组比较,正常组BF、BV及PS的差异均有统计学意义(P<0.05),MTT的差异无统计学意义(P>0.05);正常乳腺组与纤维腺瘤组、增生病组比较,BF及BV的差异均有统计学意义(P<0.05),MTT及PS的差异均无统计学意义(P>0.05);乳腺癌组与纤维腺瘤组比较,其BF、PS的差异有统计学意义(P<0.05),BV及MTT的差异无统计学意义(P>0.05);乳腺癌组与增生病组比较,其BF、BV及PS的差异均有统计学意义(P<0.05),MTT的差异无统计学意义(P>0.05);增生病组与纤维腺瘤组比较,其BF、BV、MTT及PS的差异均无统计学意义(P>0.05).正常组与乳腺癌组分别呈低灌注、高灌注状态,纤维腺瘤组及增生病组均呈较高灌注状态.[结论]64层螺旋CT作为先进的影像检查技术,其灌注成像能从血流动力学和影像学角度为各类乳腺疾病的进行较为准确的诊断.%[Objective] To study and evaluate multi-slice spiral CT perfusion imaging in the diagnosis of breast diseases the effect and value. [Methods] 61 patients through clinical examination or mammography of women with suspected breast disease patients with 64-slice spiral CT perfusion imaging. The pathology types were divided into three groups: hyperplasia group (n = 14), fibroadenoma group (n - 19) and breast cancer group (n = 20), and conlralaterai

  9. 螺旋CT图像环形伪影产生机制及处理方法%Spiral ring Artifacts of CT image Generation Mechanism and Processing Method

    Institute of Scientific and Technical Information of China (English)

    何卫红; 方向军; 邓承健; 范锟

    2015-01-01

    Objective: The ring artifacts not only reduces the quality of the image, the image back to the late segmentation, image data mining and rely on images as data reconstruction caused a great inlfuence. Study of ring artifacts in mechanism and treatment method, artifacts can produce a reduction of spiral CT examination, provide beter images for clinical.Methods We colected from 181 patients with different type and degree of ring artifacts of CT image case, a systematic study, in which the head CT scanning in 74 cases, 45 cases chest scan, scan of the abdomen in 42 cases, 20 cases of other site.Results: Through the analysis of ring artifacts in various parts of the basic reason, given the ring artifacts, method and can reduce and correction of ring artifacts.Conclusion: Ring artifact was affected by various factors, the causes of cognitive generated can be avoided, suppresses the artifacts produced, grasp the ring artifact processing method can remove image artifacts, has the vital signiifcance to optimize image quality and improve the quality and effciency of clinical medical diagnosis.%目的:环形伪影不仅降低了图像的质量,还给后期的图像分割,图像数据挖掘以及依靠图像为数据的三维重建等造成很大影响。研究环形伪影产生机制及处理方法,可以减少螺旋C T检查时产生的伪影,为临床提供更好的影像资料。方法:收集本院181位患者不同类型和不同程度CT图像环形伪影病例,进行系统研究,其中头部扫描74例,胸部扫描45例,腹部扫描42例,其他部位20例。结果:通过对各部位产生的环形伪影进行分析,给出了环形伪影产生的基本原因,及能够减少和校正环形伪影的方法。结论:环形伪影的产生受多种因素的影响,认知其产生的原因可以避免,抑制伪影的产生,掌握环形伪影处理方法可以消除图像伪影,对优化图像质量和提高临床医学诊断质量和效率具有重要意义。

  10. Efficient Algorithm for Rectangular Spiral Search

    Science.gov (United States)

    Brugarolas, Paul; Breckenridge, William

    2008-01-01

    An algorithm generates grid coordinates for a computationally efficient spiral search pattern covering an uncertain rectangular area spanned by a coordinate grid. The algorithm does not require that the grid be fixed; the algorithm can search indefinitely, expanding the grid and spiral, as needed, until the target of the search is found. The algorithm also does not require memory of coordinates of previous points on the spiral to generate the current point on the spiral.

  11. Stellar Spirals in Triaxial Dark Matter Halos

    Science.gov (United States)

    Hu, Shaoran; Sijacki, Debora

    2017-03-01

    Two-armed grand-design spirals may form if the shape of its dark matter halo changes abruptly enough. The feasibility of such a mechanism is tested in realistic simulations. The interplay of such externally-driven spirals and self-induced transient spirals is then studied. Subhaloes are also found to lead to transient grand-design spiral structures when they impact the disk.

  12. SCTM对腰椎管狭窄症的影像病理学研究%The Image Pathologic Studies of Narrowing of Lumbar Vertebrae with SCTM (Spiral Computer Tomogram Myelography

    Institute of Scientific and Technical Information of China (English)

    唐志伟; 陈双; 陈德基; 陈洁兰; 李树欣

    2001-01-01

    Objective To evaluate the imaging technology and clinical application of spiral CTM.Methods 42 patients were examined with SCTM. The images were analyzed and reconstructed by computer software. Results Among 42 cases, there were 27 of lumbar disc diseases, 2 of congenital bony narrowing of vertebral canal, 2 of hyperosteogeny at rear edge of vertebra, 5 of vertebral dislocation, 3 of pachynsis of yellow ligaments. All the patients received operative treatments. The SCTM made 100% positive diagnosis. Computer reconstruction software can provide the multi-plane and multi-angle images, illustrating the vertebral canal and subarachnoid cavity, the appearance, structure and connectivity of spinal nerves.Conclusions SCTM-MPR can clearly illustrate the anatomy of vertebral canal and its contents, the pathologic changes, making a precise localization of the focus. It's believed that SCTM can be very valuable in clinical application of narrowing of vertebral canal.%目的探讨螺旋CT椎管造影(SCTM)成像技术及临床应用价值.方法对42例腰椎管狭窄症患者进行T椎管造影检查,图像经计算机多平面重建软件处理.结果在42例患者中,椎间盘病变27例,先天性骨性椎管狭窄2例,椎体后缘增生骨刺2例,椎体滑脱5例,黄韧带肥厚3例,椎间盘突出术后及疤痕增生3例.全部病例均行手术治疗并证实.后处理多平面重建图像能提供不同平面、多角度、多方位的任意轴面(直面、曲面)影像,突出显示椎管内蛛网膜下腔及脊神经根的形态、结构、位置及其连续性改变.结论 SCTM-MPR能全面地清晰显示受检段脊柱及椎管内各解剖层次及其病理改变,提高病变定位及定性的准确性,对腰椎管狭窄症的诊断具有较高的临床实用价值.

  13. Cirrhosis:CT grading with 64-slice spiral CT perfusion imaging%肝硬化CT分级的64层螺旋CT灌注成像分析

    Institute of Scientific and Technical Information of China (English)

    陈勇; 郝凯; 尚英杰; 石俊英; 杨文魁

    2012-01-01

    目的 探讨肝硬化CT分级的临床价值.方法 对17例健康正常志愿者、54例肝硬化患者行CT灌注扫描,测量其血流量(BF)、血容量(BV)、肝动脉分数(HAF)、对比剂平均通过时间(MTT)、血管表面通透性(PS),对获得的相应灌注图进行肝硬化分级分析.结果 CT分级肝硬化程度越重,BF、BV越小,MTT、HAF、PS、肝动脉灌注量(HAP)越大.HAF、HAP在正常肝与轻、中、重度肝硬化之间有明显差异,HAF在中、重度肝硬化组明显增高.HAP在重度肝硬化组明显增高,PS、MTT在各组之间没有统计学意义.结论 通过肝脏的CT灌注研究,进一步证明了肝硬化CT分级确实与肝脏的灌注有一定关系,对临床肝硬化评估有一定价值.%Objective To evaluate the clinical value in grading of liver cirrhosis with 64-slice spiral CT perfusion imaging. Methods 17 healthy volunteers and 54 patients with liver cirrhosis underwent liver CT perfusion scanning. The blood flow(BF) , blood vol-ume(BV) , hepatic arterial fraction( HAF) , contrast agent mean transit time(MTT) and vascular permeability surface) PS) were measured on CT perfusion maps. Results CT perfusion imaging showed that the serious of cirrhosis,the lower of perfusion values of BF and BV,the higher of MTT,HAF,PS and hepatic arterial perfusionf HAP). There were significant differences between the normal liver and mild,moderate and severe cirrhosis in HAF and HAP,and HAF in moderate and severe cirrhosis of the liver was significantly increased. HAP in severe liver cirrhosis was significantly higher, PS, MTT between groups was not statistically significant. Conclusion By liver CT perfusion imaging study shows that the CT grading of cirrhosis is of certain relativity with liver perfusion, which is of significant value in evaluating cirrhosis clinically.

  14. Application Research on Multi-slice Spiral CT Perfusion Imaging in Patients with Acute Cerebral Infarction%多层螺旋 CT 灌注成像在急性脑梗死患者的应用研究

    Institute of Scientific and Technical Information of China (English)

    罗友琛

    2014-01-01

    目的:探讨急性脑梗死患者多层螺旋 CT 灌注成像特点,及其与临床预后的关系。方法选择符合标准的患者40例,行 CT 灌注成像检查,计算脑血流量(CBF)、脑血容量(CBV)、平均通过时间(MTT)及峰值时间(TTP);分别在入院时和治疗后14d 采用美国国立卫生研究院卒中量表(NIHSS)评价临床神经功能缺损,计算缺血脑组织的可恢复比率(PRR)和神经功能恢复比率。结果脑梗死病灶中心 CBV 及 CBF 最低,健侧最高,而缺血半暗带居中,差异有统计学意义(P 0.05);PRR 与患者治疗14d 时 NIHSS 评分存在负相关性(r =-0.340, P 0. 05),negatively dependent of those at day 14 after treatment (r = - 0. 340,P < 0. 05) and positive-ly dependent of patient’s neural functional recovery ratio (r = 0. 467,P < 0. 05). Conclusion Multi-slice spiral CT perfusion im-aging can reflecthemodynamic changes in acute cerebral infarction lesions and their perihemodynamic changes. PRR is closely de-pendent of the neural functional recovery. It can serve as a reliable theoretical basis for clinical treatment.

  15. Bioagent detection using miniaturized NMR and nanoparticle amplification : final LDRD report.

    Energy Technology Data Exchange (ETDEWEB)

    Clewett, C. F. M.; Adams, David Price; Fan, Hongyou; Williams, John D.; Sillerud, Laurel O.; Alam, Todd Michael; Aldophi, Natalie L. (New Mexico Resonance, Albuquerque, NM); McDowell, Andrew F. (New Mexico Resonance, Albuquerque, NM)

    2006-11-01

    This LDRD program was directed towards the development of a portable micro-nuclear magnetic resonance ({micro}-NMR) spectrometer for the detection of bioagents via induced amplification of solvent relaxation based on superparamagnetic nanoparticles. The first component of this research was the fabrication and testing of two different micro-coil ({micro}-coil) platforms: namely a planar spiral NMR {micro}-coil and a cylindrical solenoid NMR {micro}-coil. These fabrication techniques are described along with the testing of the NMR performance for the individual coils. The NMR relaxivity for a series of water soluble FeMn oxide nanoparticles was also determined to explore the influence of the nanoparticle size on the observed NMR relaxation properties. In addition, The use of commercially produced superparamagnetic iron oxide nanoparticles (SPIONs) for amplification via NMR based relaxation mechanisms was also demonstrated, with the lower detection limit in number of SPIONs per nanoliter (nL) being determined.

  16. Inspired Spirals. Teaching Art with Art.

    Science.gov (United States)

    Hubbard, Guy

    2001-01-01

    Discusses spirals in nature, man-made objects, and art. Focuses on art that incorporates the spiral, including works by M. C. Escher and Frank Lloyd Wright, an African headdress, and a burial urn. Describes activities to help students make spirals of their own, such as constructing a coil clay pot. (CMK)

  17. Scale height determination of spiral galaxies

    Institute of Scientific and Technical Information of China (English)

    计朝晖; 商朝晖; 彭秋和

    1997-01-01

    The method adopted here is based on the rigorous solution of Poison’s equation for logarithmic disturbance density within finite thickness galaxies. After their spiral arms are fitted directly with logarithmic spirals, the morphological parameters, scale heights and their relative errors for 32 spiral galaxies, such as NGC4814, are ob-tained.

  18. Solitons in spiraling Vogel lattices

    CERN Document Server

    Kartashov, Yaroslav V; Torner, Lluis

    2012-01-01

    We address light propagation in Vogel optical lattices and show that such lattices support a variety of stable soliton solutions in both self-focusing and self-defocusing media, whose propagation constants belong to domains resembling gaps in the spectrum of a truly periodic lattice. The azimuthally-rich structure of Vogel lattices allows generation of spiraling soliton motion.

  19. The enigma of auroral spirals

    Science.gov (United States)

    Haerendel, G.

    One of the most spectacular forms that the aurora borealis can assume is the large-scale spiral Spirals are dominantly observed along the poleward boundary of the auroral oval during active periods Two concepts have been pursued in explaining their origin and in particular the counterclockwise sense of rotation of the luminous structures when viewed along the magnetic field direction An essentially magnetostatic theory following Hallinan 1976 attributes the spiral pattern to the twisting of field-lines caused by a centrally located upward field-aligned current According to Oguti 1981 and followers a clockwise rotation of the plasma flow produces the anticlockwise structure There are observations seemingly confirming or contradicting either theory In this paper it is argued that both concepts are insufficient in that only parts of the underlying physics are considered Besides field-aligned currents and plasma flow one has to take into at least two further aspects The ionospheric conductivity modified by particle precipitation has an impact on the magnetospheric plasma dynamics Furthermore auroral arcs are not fixed entities subject to distortions by plasma flows or twisted field-lines but sites of transient releases of energy We suggest that auroral spirals are ports of entry or exit of plasma into or out of the auroral oval This way it can be understood why a clockwise plasma flow can create an anticlockwise luminous pattern

  20. The clinical research of multi-slice spiral CT in intestinal imaging%多层螺旋CT肠道成像的临床研究

    Institute of Scientific and Technical Information of China (English)

    高剑波; 郭华; 耿尚文; 张永高

    2011-01-01

    Objective To investigate the value and usefulness of optimized multislice CT enterography (MSCTE) with orally administered isosmotic mannitol (2. 5%) as negative contrast in demonstrating the small bowel and its abnormality. Methods Forty patients suspected of intestinal tumors were randomly divided into two groups and underwent conventional or optimized MSCTE. The expansion degree of bowel lumen and the thickness of bowel wall were evaluated for the six segments of the small intestine. The other 20 patients suspected of gastrointestinal diseases underwent gastrointestinal CT imaging.The expansion degree of bowel lumen and the wall thickness of bowel wall were statistically analyzed with Chi-Square test and t test. Results The wall thickness of the stomach, ileum and colon were (2. 56 ±0.52) ,(1.41 ±0. 15),(1.46 ±0. 13),(1.91 ±0. 25), (1.97 ±0.26),(2.01 ±0. 19), (2. 04 ±0.24)and (2. 05 ±0. 18)mm. Optimized method was superior to conventional method in the expansion degree of the second and third segments of the small intestine (P < 0. 05) . There was no significant differences between two groups in the expansion degree and depiction of mucosa for the other segments of small intestine (P > 0. 05). The gastrointestinal CT imaging was poor in the depiction of the duodenum and jejunum, but stomach, ileum and colon were fully illustrated. Conclusion Optimized MSCTE was superior to conventional method in demonstrating the small bowel, and gastrointestinal CT imaging can expand diagnostic scope because of good observation of whole gastrointestinal tract.%目的 探讨口服2.5%等渗甘露醇多层螺旋CT肠道成像(MSCTE)的优势及其临床价值.方法 40例临床怀疑为小肠肿瘤疾病者采用完全随机法分为2组,分别行常规法与改良法CT小肠MSCTE,对比2种方法观察6段小肠(1段为十二指肠,2段为空肠近段,3段为空肠远段,4、5、6段为回肠)的管腔扩张度及管壁厚度.20例临床怀疑胃肠道疾病患者

  1. The One-step Imaging Study of Acute Chest Pain Trilogy by 64 Slice Spiral CT%急性胸痛三联症64层螺旋CT“一站式成像”的研究

    Institute of Scientific and Technical Information of China (English)

    李欣; 孙吉林; 戴国华; 付英杰; 李志远; 柳溪

    2011-01-01

    [Abstract] Objective To investigate the image quality and ability of one-time unified examination of the 64-slice spiral CT(MSCT)in showing coronary artery, pulmonary artery and aorta. Materials and Methods 60 patients with acute chest pain received unified examination of coronary artery .pulmonary artery, aorta with 64-slice MSCT using ECG-gated function respectively. The coronary artery,pulmonary artery and aorta were imaged by using a variety of reconstruction techniques compare to 50 cases with pure 64-slice MSCT coronary angiography ,30 cases with pulmonary artery imaging and 20 cases with aortic imaging. The results from the above examinations were analyzed to evaluate whether or not the quality of the images could meet the need of the clinical diagnosis. Results The average scan time of one step examination was(8.0 ± 1.5)S,and the dose of contrast medium injected was 100 ml,and the injection flow rate of 4.0 -4.5 ml/s. There was significant difference between the chest pain group and the control group in the images of the coronary artery (P 0.05;P=0.44, >0.05;P =0.068, >0.05).The image quality of the chest pain group was as good as the one of the control group. There was significant difference between two groups and intragroup in the images of the central, peripheral and whole pulmonary artery in chest pain group and the control group (P<0.01 ;P<0.01 ;P<0.01).The image quality of the chest pain group was better than the one of the control group. Conclusion The one-step examination of coronary artery .pulmonary artery,aorta by 64-slice MSCT can be finished within 10 seconds. The image quality of aorta, pulmonary artery is excellent. There is no significant difference between the image quality of the single aorta imaging and the unified examination of the MSCT,of which image quality is better than that of single pulmonary artery MSCT. The image of the coronary artery in one time unified examination is good,can meet the needs of the clinical diagnosis,but is

  2. NMR imaging estimates of muscle volume and intramuscular fat infiltration in the thigh: variations with muscle, gender, and age.

    Science.gov (United States)

    Hogrel, Jean-Yves; Barnouin, Yoann; Azzabou, Noura; Butler-Browne, Gillian; Voit, Thomas; Moraux, Amélie; Leroux, Gaëlle; Behin, Anthony; McPhee, Jamie S; Carlier, Pierre G

    2015-06-01

    Muscle mass is particularly relevant to follow during aging, owing to its link with physical performance and autonomy. The objectives of this work were to assess muscle volume (MV) and intramuscular fat (IMF) for all the muscles of the thigh in a large population of young and elderly healthy individuals using magnetic resonance imaging (MRI) to test the effect of gender and age on MV and IMF and to determine the best representative slice for the estimation of MV and IMF. The study enrolled 105 healthy young (range 20-30 years) and older (range 70-80 years) subjects. MRI scans were acquired along the femur length using a three-dimension three-point Dixon proton density-weighted gradient echo sequence. MV and IMF were estimated from all the slices. The effects of age and gender on MV and IMF were assessed. Predictive equations for MV and IMF were established using a single slice at various femur levels for each muscle in order to reduce the analysis process. MV was decreased with aging in both genders, particularly in the quadriceps femoris. IMF was largely increased with aging in men and, to a lesser extent, in women. Percentages of MV decrease and IMF increase with aging varied according to the muscle. Predictive equations to predict MV and IMF from single slices are provided and were validated. This study is the first one to provide muscle volume and intramuscular fat infiltration in all the muscles of the thigh in a large population of young and elderly healthy subjects.

  3. NMR exposure sensitizes tumor cells to apoptosis.

    Science.gov (United States)

    Ghibelli, L; Cerella, C; Cordisco, S; Clavarino, G; Marazzi, S; De Nicola, M; Nuccitelli, S; D'Alessio, M; Magrini, A; Bergamaschi, A; Guerrisi, V; Porfiri, L M

    2006-03-01

    NMR technology has dramatically contributed to the revolution of image diagnostic. NMR apparatuses use combinations of microwaves over a homogeneous strong (1 Tesla) static magnetic field. We had previously shown that low intensity (0.3-66 mT) static magnetic fields deeply affect apoptosis in a Ca2+ dependent fashion (Fanelli et al., 1999 FASEBJ., 13;95-102). The rationale of the present study is to examine whether exposure to the static magnetic fields of NMR can affect apoptosis induced on reporter tumor cells of haematopoietic origin. The impressive result was the strong increase (1.8-2.5 fold) of damage-induced apoptosis by NMR. This potentiation is due to cytosolic Ca2+ overload consequent to NMR-promoted Ca2+ influx, since it is prevented by intracellular (BAPTA-AM) and extracellular (EGTA) Ca2+ chelation or by inhibition of plasma membrane L-type Ca2+ channels. Three-days follow up of treated cultures shows that NMR decrease long term cell survival, thus increasing the efficiency of cytocidal treatments. Importantly, mononuclear white blood cells are not sensitised to apoptosis by NMR, showing that NMR may increase the differential cytotoxicity of antitumor drugs on tumor vs normal cells. This strong, differential potentiating effect of NMR on tumor cell apoptosis may have important implications, being in fact a possible adjuvant for antitumor therapies.

  4. On Generalized Euler Spirals in E^3

    OpenAIRE

    Saracoglu, Semra

    2012-01-01

    The Cornu spirals on plane are the curves whose curvatures are linear. Generalized planar cornu spirals and Euler spirals in E^3, the curves whose curvatures are linear are defined in [1,5]. In this study, these curves are presented as the ratio of two rational linear functions. Also here, generalized Euler spirals in E^3 has been defined and given their some various characterizations. The approach I used in this paper is useful in understanding the role of Euler spirals in E^3 in differentia...

  5. 多层螺旋CT肠道造影在溃疡性结肠炎活动期的影像分析%The analysis for images of multi-slice spiral CTE performance levels in active ulcerative ;colitis

    Institute of Scientific and Technical Information of China (English)

    赵宾; 王继红

    2016-01-01

    Objective: To investigate the imaging characteristics of the intestinal multi-slice spiral CT enterography (CTE) in active ulcerative colitis(UC), analyze and summarize its application value. Methods: A total 43 cases diagnosed with active UC from April 2014 to April 2015 in our hospital were selected and divided into mild, moderate and severe three levels with each level as a group, treated by multi-slice spiral CTE examination system based on the improved Mayo system, comparing different performances of CTE levels. Results:43 cases of UC patients participating in the study, eight patients were mild, 16 cases were moderate and 19 cases were severe. There was statistically different in the intestinal mucosa in the presence of air bubbles between the mild and moderate group (x2=21.62; P0.05). Conclusion:UC patients CTE examination, which can effectively conduct a comprehensive assessment against bowel, intestinal and parenteral, provide favorable conditions for the activity of UC clinical diagnosis and classification.%目的:观察多层螺旋CT肠道造影(CTE)在溃疡性结肠炎活动期(UC)中的成像特点,分析探讨其应用价值。方法:选取43例确诊的活动期UC患者,对其行多层螺旋CTE检查,依据改良后的Mayo系统将患者分为轻、中、重三个等级,每个等级为一组,对比不同等级患者CTE的表现。结果:43例UC患者中,8例为轻度,16例为中度,19例为重度,将三组患者多层螺旋CTE检查结果进行对比,其中轻度组与中度组对比,于肠黏膜下气泡一项上差异存在统计学意义(x2=21.62,P<0.05);中度组与重度组进行对比,于结肠袋消失情况、淋巴结肿大情况以及肠壁分层情况3个项目上差异有统计学意义(x2=25.95,x2=17.46,x2=19.46;P<0.05);而于肠黏膜强化程度增加、肠壁增厚、直肠周围脂肪沉积以及肠腔狭窄等项目上,差异均无统计学意义(F=0.36,F=1.58,F=0.31,P>0.05)

  6. Interaction of multiarmed spirals in bistable media.

    Science.gov (United States)

    He, Ya-feng; Ai, Bao-quan; Liu, Fu-cheng

    2013-05-01

    We study the interaction of both dense and sparse multiarmed spirals in bistable media modeled by equations of the FitzHugh-Nagumo type. A dense one-armed spiral is characterized by its fixed tip. For dense multiarmed spirals, when the initial distance between tips is less than a critical value, the arms collide, connect, and disconnect continuously as the spirals rotate. The continuous reconstruction between the front and the back drives the tips to corotate along a rough circle and to meander zigzaggedly. The rotation frequency of tip, the frequency of zigzagged displacement, the frequency of spiral, the oscillation frequency of media, and the number of arms satisfy certain relations as long as the control parameters of the model are fixed. When the initial distance between tips is larger than the critical value, the behaviors of individual arms within either dense or sparse multiarmed spirals are identical to that of corresponding one-armed spirals.

  7. Localized spirals in Taylor-Couette flow.

    Science.gov (United States)

    Heise, M; Abshagen, J; Küter, D; Hochstrate, K; Pfister, G; Hoffmann, Ch

    2008-02-01

    We present a type of spiral vortex state that appears from a supercritical Hopf bifurcation below the linear instability of circular Couette flow in a Taylor-Couette system with rigid end plates. These spirals have been found experimentally as well as numerically as "pure" states but also coexist with "classical" spirals (or axially standing waves for smaller systems) which typically appear from linear instability in counterrotating Taylor-Couette flow. These spiral states have an axial distribution of the strongly localized amplitude in the vicinity of the rigid end plates that confine the system in the axial direction. Furthermore, they show significantly different oscillation frequencies compared to the critical spiral frequencies. Despite the localization of the amplitude near the ends, the states appear as global states with spirals that propagate either toward the middle from each end of the system or vice versa. In contrast to classical spirals, these states exhibit a spatial or a spatiotemporal reflection symmetry.

  8. Evaluation of 128-slice spiral CT whole brain perfusion imaging in grading infiltrating astrocytomas%128层螺旋CT全脑灌注对浸润性星形细胞瘤的分级评估

    Institute of Scientific and Technical Information of China (English)

    曾文兵; 王毅; 汪明全; 吴炅; 刘兴华; 罗江平; 温云

    2011-01-01

    目的:评价128层螺旋CT全脑灌注(CTP)对浸润性星形细胞瘤分级定性诊断的价值.方法:选择我院90例脑肿瘤患者进行CTP检查,经手术和病理学证实为浸润性星形细胞瘤(Ⅱ~Ⅳ级)者46例纳入本研究对象.CTP采用SOMATOM Definition AS型128层螺旋CT机进行灌注扫描,应用后处理工作站对原始数据进行后处理.获得时间-密度曲线(TDC).测定肿瘤区和对侧正常组织的脑血流量(CBF)、脑血容量(CBV)、毛细血管表面通透性(PS)及对比剂达峰值时间(TTP),并对灌注参数进行统计学分析.结果:在所有病例中,全脑灌注图像平均视觉评价分数明显高于传统灌注图(P<0 01).且对病变定位更为精确.星形细胞肿瘤高级别组的CBF、CBV和PS值均显著高于低级别组(P<0.01).而TTP值的差异无统计学意义(P>0.05).ROC曲线分析表明,CBF、CBV和PS值对鉴别高、低级别星形细胞肿瘤的ROC曲线下面积分别为0.925、0.897和0.954.采用CBF≥72.052ml/min/100g,CBV≥4.293ml/100g和PS≥6.337ml/min/100g作为分界点对鉴别高低级别星形细胞肿瘤的敏感性均为87.2%,特异性分别是83.5%、83.5%和93.0%.结论:128层螺旋CT全脑灌注有利于脑肿瘤的术前整体评估和精确定位;CTP参数CBF、CBV及PS值及TDC曲线对鉴别高、低级别星形细胞肿瘤具有较高的敏感性和特异性.%Objective:To evaluate the value of 128-slicc spiral CT whole brain perfusion (CTP) imaging in grading infil-traiing astrocytomas. Methods: Ninety patients with brain rumors underwent CTP examination and forty-six of them with astrocytic tumors (Ⅱ -Ⅳ) confirmed by operation and pathology were selected as the object of this study. 128-slice helical CT whole brain perfusion imaging was performed in the 46 patients, and the data were analyzed by the software. Cerebral blood flow (CBF). Cerebral blood volume (CBV). Time to peak (TTP) and permeability surface (PS> on the maximum perfusion area

  9. In situ microscopic studies on the structures and phase behaviors of SF/PEG films using solid-state NMR and Raman imaging.

    Science.gov (United States)

    Chen, Congheng; Yao, Ting; Tu, Sidong; Xu, Weijie; Han, Yi; Zhou, Ping

    2016-06-28

    In order to overcome the drawbacks of silk fibroin (SF)-based materials, SF has been blended with some polymers. Before using the blend material, understanding of the structures and phase behaviors of the blend is thought to be essential. In this study, solid-state (13)C CP-MAS NMR and Raman imaging techniques were used to study the structures and phase behaviors of blends of SF with polyethylene glycol (PEG) at a molecular weight that varied from 2 to 20 kDa and a blend ratio of SF/PEG from 95/5 to 70/30 (w/w%) at the molecular and microscopic levels. It is found that the conformational transition of SF to the β-sheet increased as the PEG content increased, while the amount of the formed β-sheet conformers was decreased as the PEG molecular weight increased for a given content. It is also observed that SF was incompatible with PEG to some extent. The phase separation into "sea" and "island" domains took place in the SF/PEG blend films. SF was dominantly present in the "sea" domain, while PEG in the "island" domains. The conformation of SF in the interface between SF and PEG was changed to the β-sheet, while that in the protein-rich domain remained in the random coil and/or helix conformation. These observations suggest that the specifically expected materials, for example, the silk-based microspheres or scaffold materials can be manufactured by controlling the molecular weight and content of PEG in the blend system.

  10. HST detection of spiral structure in two Coma Cluster dwarf galaxies

    CERN Document Server

    Graham, A W; Guzmán, R; Graham, Alister W.; Jerjen, Helmut; Guzman, Rafael

    2003-01-01

    We report the discovery of (stellar) spiral-like structure in Hubble Space Telescope images of two dwarf galaxies (GMP 3292 and GMP 3629) belonging to the Coma cluster. GMP 3629 is the faintest such galaxy detected in a cluster environment, and it is the first such galaxy observed in the dense Coma cluster. The large bulge and the faintness of the broad spiral-like pattern in GMP 3629 suggests that its disk may have been largely depleted. >We may therefore have found an example of the ``missing link'' in theories of galaxy evolution which have predicted that dwarf spiral galaxies, particularly in clusters, evolve into dwarf elliptical galaxies.

  11. THEMIS ground-space observations during the development of auroral spirals

    Directory of Open Access Journals (Sweden)

    A. Keiling

    2009-11-01

    Full Text Available A simultaneous observation of an auroral spiral and its generator region in the near-Earth plasma sheet is rather unlikely. Here we present such observations using the THEMIS spacecraft as well as the THEMIS ground network of all-sky imagers and magnetometers. Two consecutive auroral spirals separated by approximately 14 min occurred during a substorm on 19 February 2008. The spirals formed during the expansion phase and a subsequent intensification, and were among the brightest features in the aurora with diameters of 200–300 km. The duration for the formation and decay of each spiral was less than 60 s. Both spirals occurred shortly after the formation of two oppositely rotating plasma flow vortices in space, which were also accompanied by dipolarizations and ion injections, at ~11 RE geocentric distance. Observations and model calculations also give evidence for a magnetic-field-aligned current generation of approximately 0.1 MA via the flow vortices, connecting the generator region of the spirals with the ionosphere, during the formation of both spirals. In the ionosphere, a pair of equivalent ionospheric current (EIC vortices with opposite rotations (corresponding to upward and downward currents was present during both auroral spirals with enhanced EICs and ionospheric flows at the locations of the auroral spirals and along the auroral arcs. The combined ground and space observations suggest that each auroral spiral was powered by two oppositely rotating plasma flow vortices that caused a current enhancement in the substorm current wedge.

  12. Spiral shocks in the accretion disc of IP Peg during outburst maximum

    Science.gov (United States)

    Harlaftis, E. T.; Steeghs, D.; Horne, K.; Martín, E.; Magazzú, A.

    1999-06-01

    In response to our recent discovery of spiral arms in the accretion disc of IP Peg during rise to outburst, we have obtained time-resolved spectrophotometry of IP Peg during outburst maximum. In particular, indirect imaging of He II 4686, using Doppler tomography, shows a two-arm spiral pattern on the disc image, which confirms repeatability over different outbursts. The jump in He II intensity (a factor of more than 2) and in velocity (~ 200-300 km s^-1) clarifies the shock nature of the spiral structure. The He II shocks show an azimuthal extent of ~ 90 deg, a shallow power-law emissivity ~ V^-1, an upper limit of 30 deg in opening angle, and a flux contribution of 15 per cent of the total disc emission. We discuss the results in view of recent simulations of accretion discs which show that spiral shocks can be raised in the accretion disc by the secondary star.

  13. NMR and MRI apparatus and method

    Science.gov (United States)

    Clarke, John; Kelso, Nathan; Lee, SeungKyun; Moessle, Michael; Myers, Whittier; McDermott, Robert; ten Haken, Bernard; Pines, Alexander; Trabesinger, Andreas

    2007-03-06

    Nuclear magnetic resonance (NMR) signals are detected in microtesla fields. Prepolarization in millitesla fields is followed by detection with an untuned dc superconducting quantum interference device (SQUID) magnetometer. Because the sensitivity of the SQUID is frequency independent, both signal-to-noise ratio (SNR) and spectral resolution are enhanced by detecting the NMR signal in extremely low magnetic fields, where the NMR lines become very narrow even for grossly inhomogeneous measurement fields. Additional signal to noise benefits are obtained by use of a low noise polarization coil, comprising litz wire or superconducting materials. MRI in ultralow magnetic field is based on the NMR at ultralow fields. Gradient magnetic fields are applied, and images are constructed from the detected NMR signals.

  14. Scalable Automated Detection of Spiral Galaxy Arm Segments

    CERN Document Server

    Davis, Darren R

    2014-01-01

    Given an approximately centered image of a spiral galaxy, we describe an entirely automated method that finds, centers, and sizes the galaxy and then automatically extracts structural information about the spiral arms. For each arm segment found, we list the pixels in that segment and perform a least-squares fit of a logarithmic spiral arc to the pixels in the segment. The algorithm takes about 1 minute per galaxy, and can easily be scaled using parallelism. We have run it on all ~644,000 Sloan objects classified as "galaxy" and large enough to observe some structure. Our algorithm is stable in the sense that the statistics across a large sample of galaxies vary smoothly based on algorithmic parameters, although results for individual galaxies can sometimes vary in a non-smooth but easily understood manner. We find a very good correlation between our quantitative description of spiral structure and the qualitative description provided by humans via Galaxy Zoo. In addition, we find that pitch angle often varie...

  15. Molecular Distribution in the Spiral Arm of M51

    CERN Document Server

    Watanabe, Yoshimasa; Sorai, Kazuo; Ueda, Junko; Yamamoto, Satoshi

    2016-01-01

    Molecular line images of 13CO, C18O, CN, CS, CH3OH, and HNCO are obtained toward the spiral arm of M51 at a 7" times 6" resolution with the Combined Array for Research in Millimeter-wave Astronomy (CARMA). Distributions of the molecules averaged over a 300 pc scale are found to be almost similar to one another and to essentially trace the spiral arm. However, the principal component analysis shows a slight difference of distributions among molecular species particularly for CH3OH and HNCO. These two species do not correlate well with star-formation rate, implying that they are not enhanced by local star-formation activities but by galactic-scale phenomena such as spiral shocks. Furthermore, the distribution of HNCO and CH3OH are found to be slightly different, whose origin deserves further investigation. The present results provide us with an important clue to understanding the 300 pc scale chemical composition in the spiral arm and its relation to galactic-scale dynamics.

  16. Spiral Galaxies as Chiral Objects?

    CERN Document Server

    Capozziello, S; Capozziello, Salvatore; Lattanzi, Alessandra

    2005-01-01

    Spiral galaxies show axial symmetry and an intrinsic 2D-chirality. Environmental effects can influence the chirality of originally isolated stellar systems and a progressive loss of chirality can be recognised in the Hubble sequence. We point out a preferential modality for genetic galaxies as in microscopic systems like aminoacids, sugars or neutrinos. This feature could be the remnant of a primordial symmetry breaking characterizing systems at all scales.

  17. NMR of lignins

    Science.gov (United States)

    John Ralph; Larry L. Landucci

    2010-01-01

    This chapter will consider the basic aspects and findings of several forms of NMR spectroscopy, including separate discussions of proton, carbon, heteronuclear, and multidimensional NMR. Enhanced focus will be on 13C NMR, because of its qualitative and quantitative importance, followed by NMR’s contributions to our understanding of lignin...

  18. Spiral mining for lunar volatiles

    Science.gov (United States)

    Schmitt, H. H.; Kulcinski, G. L.; Sviatoslavsky, I. N.; Carrier, W. D., III

    Lunar spiral mining, extending outward from a periodically mobile central power and processing station represents an alternative for comparison with more traditional mining schemes. In this concept, a mining machine would separate regolith fines and extract the contained volatiles. Volatiles then would be pumped along the miner's support arm to the central station for refining and for export or storage. The basic architecture of the central processing station would be cylindrical. A central core area could house the power subsystem of hydrogen-oxygen engines or fuel cells. Habitat sections and other crew occupied areas could be arranged around the power generation core. The outer cylinder could include all volatile refining subsystems. Solar thermal power collectors and reflectors would be positioned on top of the central station. Long term exploitation of a volatile resource region would begin with establishment of a support base at the center of a long boundary of the region. The mining tract for each spiral mining system would extend orthogonal to this boundary. New spiral mining systems would be activated along parallel tracts as demand for lunar He-3 and other solar wind volatiles increased.

  19. Transient spirals as superposed instabilities

    Energy Technology Data Exchange (ETDEWEB)

    Sellwood, J. A. [Department of Physics and Astronomy, Rutgers University, 136 Frelinghuysen Road, Piscataway, NJ 08854 (United States); Carlberg, R. G., E-mail: sellwood@physics.rutgers.edu, E-mail: carlberg@astro.utoronto.ca [Department of Astronomy and Astrophysics, University of Toronto, Toronto, ON M5S 3H4 (Canada)

    2014-04-20

    We present evidence that recurrent spiral activity, long manifested in simulations of disk galaxies, results from the superposition of a few transient spiral modes. Each mode lasts between 5 and 10 rotations at its corotation radius where its amplitude is greatest. The scattering of stars as each wave decays takes place over narrow ranges of angular momentum, causing abrupt changes to the impedance of the disk to subsequent traveling waves. Partial reflections of waves at these newly created features allows new standing-wave instabilities to appear that saturate and decay in their turn, scattering particles at new locations, creating a recurring cycle. The spiral activity causes the general level of random motion to rise, gradually decreasing the ability of the disk to support further activity unless the disk contains a dissipative gas component from which stars form on near-circular orbits. We also show that this interpretation is consistent with the behavior reported in other recent simulations with low-mass disks.

  20. Diagnostic Value of Brain Perfusion Imaging with 64 Multi-Detector Spiral CT in Early Cerebral Infarction%64排螺旋 CT 脑灌注成像对早期脑梗死的诊断价值

    Institute of Scientific and Technical Information of China (English)

    奚彬; 盛伟华; 唐建伟; 黄松; 宋黎涛

    2014-01-01

    目的:探讨64排螺旋 CT 脑灌注成像(CT perfusion imaging,CTP)对早期脑梗死的诊断价值。方法:临床拟诊早期脑梗死患者38例,均在症状出现24 h 内行头颅 CT 平扫及 CTP 检查。将脑梗死核心区、缺血半暗带(ischemic penumbra,IP)区与健侧对应区的情况做对比分析。结果:38例患者中,15例头颅 CT 平扫发现可疑脑梗死区,主要位于大脑半球,表现为密度轻度减低、局部脑沟稍变浅等;其余23例患者 CT 平扫未发现异常。38例患者的 CTP 检查均发现灌注异常区,表现为脑梗死区脑血流量(cerebral blood flow,CBF)与脑血容量(cerebral blood volume,CBV)均较健侧对应区明显下降,对比剂平均通过时间(mean transit time,MTT)较健侧对应区缩短,对比剂达峰时间(time to peak,TTP)较健侧对应区明显延长,差异均有统计学意义(P <0.01)。早期脑梗死患者 IP 区与梗死核心区比较,CBF、CBV、MTT 及 TTP 差异均有统计学意义(P <0.01);IP区与健侧对应区比较,CBF、MTT、TTP 差异均有统计学意义(P <0.05、0.01),CBV 差异无统计学意义(P >0.05)。获得随访的18例患者中,经积极溶栓等治疗后梗死区缩小6例,梗死区消失5例,仅表现为梗死区 TTP 和 MTT 延长、CBF 和 CBV 变化不大3例,梗死区无明显变化4例。结论:64排螺旋 CTP 检查可以准确地提示早期脑梗死。%Objective:To explore the diagnostic value of CT perfusion imaging(CTP)with 64 multi-detector spiral CT in early cerebral infarction.Methods:A total of 38 patients with suspected early cerebral infarction underwent plain CT and CTP within 24 h after the onset of related symptoms.The imaging results in infarction core area,ischemic penumbra (IP) and the contralateral normal region were comparatively analyzed.Results:Early cerebral infarction,mainly in cerebral hemispheres, were suspected

  1. 鼻咽癌多层螺旋CT灌注输入动脉的选择%Selection of reference arteries with multi-slice spiral CT perfusion imaging in diagnosis of nasopharyngeal carcinoma

    Institute of Scientific and Technical Information of China (English)

    丁玲; 苏丹柯; 刘丽东; 金观桥; 赵梦鸥

    2011-01-01

    目的 分析不同输入动脉所得鼻咽癌(NPC)多层螺旋CT灌注参数值的差异.方法 对38例经病理确诊的初发NPC患者进行CT灌注扫描,每例患者均分别选择肿瘤同侧的颈内动脉(ICA组)和颈外动脉(ECA组)作为输入动脉、颈内静脉作为输出静脉进行灌注成像后处理,获得两组灌注参数.采用配对t检验分析两组灌注参数值的差异,并对两组数据进行直线相关分析.结果 两组不同血管所得灌注参数值差异均无统计学意义(P>0.05),两组数据血流量、血容量、平均通过时间和表面通透性的相关系数分别为0.879、0.630、0.525、0.695(P均<0.001),两组血管所得数据均成正相关.结论 在对NPC患者进行CT灌注成像后处理时,可根据患者血管的显示情况选择颈内动脉和(或)颈外动脉作为输入动脉.%Objective To observe the difference of multi-slice spiral CT perfusion parameters in different reference arteries in diagnosis of nasopharyngeal carcinoma (NPC). Methods Thirty-eight patients with NPC underwent CT perfusion imaging, internal carotid artery (ICA group) and external carotid artery (ECA group) were selected respectively as reference artery with CT perfusion imaging post-processing in each patient. The differences of perfusion parameters between the two groups were analyzed with paired-samples t test and linear correlation. Results Parameters derived from ICA and ECA as reference artery were not statistically different (all P>0. 05). There were positive correlation of all parameters between both groups, the correlation coefficients was 0. 879 for blood flow, 0. 630 for blood volume, 0. 525 for mean transit time and 0. 695 for permeability surface (all P<0. 001). Conclusion On the post-processing of CT perfusion imaging for NPC,internal carotid artery and external carotid arteries can both be selected as the reference artery according to their displaying.

  2. Upgrading a microscope with a spiral phase plate.

    Science.gov (United States)

    Maurer, C; Jesacher, A; Fürhapter, S; Bernet, S; Ritsch-Marte, M

    2008-04-01

    We present the implementation of a spiral phase plate in a standard bright-field microscope to enhance the contrast of phase and amplitude samples. The method can be employed in all types of microscopy where standard phase contrast methods are applicable, for example, in bright-field transmission or reflection microscopy using an illumination source with partial spatial coherence. The spiral phase filter is placed into an accessible Fourier plane of the imaging path of the microscope. It is shown that this produces not only a strong contrast enhancement but in theory also improves the spatial resolution of the microscope for white light. A series of different set-ups for transmissive or reflective samples, including epi-illumination, are presented to demonstrate the practical range of applications of this contrasting method. A minute shift of the spiral phase plate out of the centre results in relief-like images that are similar to those obtained by differential interference contrast microscopy. A series of such relief-like images can be numerically processed to obtain quantitative phase and amplitude information of the sample.

  3. An HST Archival Survey of Feathers in Spiral Galaxies

    CERN Document Server

    La Vigne, M A; Ostriker, E C; Vigne, Misty A. La; Vogel, Stuart N.; Ostriker, Eve C.

    2006-01-01

    We present a survey of spiral arm extinction substructure referred to as feathers in 223 spiral galaxies using HST WFPC2 images. The sample includes all galaxies in the RC3 catalog with cz < 5000 km/s, B_T < 15, i < 60 degrees, and types Sa--Sd with well-exposed broadband WFPC2 images. The detection frequency of delineated, periodic feathers in this sample is 20% (45 of 223). This work is consistent with Lynds (1970), who concluded that feathers are common in prototypical Sc galaxies; we find that feathers are equally common in Sb galaxies. Sb--Sc galaxies without clear evidence for feathers either had poorer quality images, or flocculent or complex structure. We did not find clearly defined feathers in any Scd--Sd galaxy. The probability of detecting feathers was highest (83%) for spirals with well-defined primary dust lanes (PDLs; the lanes which line the inner edge of an arm); well-defined PDLs were only noted in Sab--Sc galaxies. Consistent with earlier work, we find that neighboring feathers ten...

  4. Clinical neuroanatomy and diagnostic imaging of the skull. Computerized tomography and nmr imaging. 2. rev. and enlarged ed. Klinische Neuroanatomie und kranielle Bilddiagnostik. Computertomographie und Magnetresonanztomographie

    Energy Technology Data Exchange (ETDEWEB)

    Kretschmann, H.J. (Medizinische Hochschule Hannover (Germany). Abt. Neuroanatomie); Weinrich, W. (Krankenhaus Nordstadt, Hannover (Germany). Neurologische Klinik)

    1991-01-01

    In the last few years, the techniques of CT, MRI, PET and utrasonography have been improved in their diagnostic efficiency, but in spite of the much enhanced resolution achievable with the new techniques, a large part of the neurofunctional systems that are of great significance to clinical diagnostic evaluation remains in the dark. The local structure of the neurofunctional systems is derived from the data describing the position of the conductive structures such as cerebral ventricles or typical cerebral sulci or gyri. A good knowledge of the three-dimensional topography of the neuroanatomy in the skull is required for this purpose, and this is what the book at hand is intended to confer. The arteries and their vascular environment are shown in the frontal, sagittal and axial plane and are compared with drawings produced from angiographies. The information given covers the cranium viscerale, the craniocervical neighbouring areas, and the motor innervation areas of the skull. The term 'diagnostic imaging of the skull' comprises the whole head and the transitional zones. The illustration of the neurofunctional system anatomy in the tomogram presented in this book is a source of information that may serve as a guide for pathfinding in CT, MRI, PET and ultrasonography. In addition, the knowledge found in the book will help to assign clinical data to pathologic findings revealed by CT or MRI. (orig.) With 596 mostly coloured figs.

  5. Spiral modes and the Milky Way

    Science.gov (United States)

    Lin, C. C.

    Recent refinements of the density-wave theory of galactic spiral modes are reviewed, and their implications for models of the structure of the Milky Way are investigated. The quasi-stationary-spiral-structure hypothesis, the structure of D100, the WASER excitation mechanisms of pure trailing spirals and rudimentary barred spirals, and modal calculations are discussed. For the Milky Way, the finding of a one-armed spiral mode causing kinematical-distance asymmetry, and some observational verifications of the spiral-gravitational-field (SGF) model for the region within about 3 kpc of the sun are reported. The importance of constructing a plausible SGF model, rather than using a circular model, for the study of the outer regions of the Milky Way is stressed. The addition of a large halo or corona to the Galactic-mass-distribution model is found to imply only scale changes in the density-wave SGF model.

  6. RESEARCH AND IMPROVEMENT OF SPIRAL BUNKER

    Institute of Scientific and Technical Information of China (English)

    董正筑; 曹璎珞; 王启广

    1996-01-01

    A great attention has been paid to slowing the degradation of coal nowadays. The spiral bunker is the main measure to lower the degradation. In this paper the application and research of spiral bunker are introduced. And two non-normal spiral chutes are discussed. One is in the tangential direction of the inner wall of the bunker, another is in the direction of the diameter of the bunker. Mathematical models of the non-normal spiral chutes are set up to optimize the geometrical parameters of the spiral curved surface, which would ensure that coal travels smoothly to the bottom of the bunker. The results would be useful for designing and retrofitting the spiral bunker.

  7. 3D design and electric simulation of a silicon drift detector using a spiral biasing adapter

    Science.gov (United States)

    Li, Yu-yun; Xiong, Bo; Li, Zheng

    2016-09-01

    The detector system of combining a spiral biasing adapter (SBA) with a silicon drift detector (SBA-SDD) is largely different from the traditional silicon drift detector (SDD), including the spiral SDD. It has a spiral biasing adapter of the same design as a traditional spiral SDD and an SDD with concentric rings having the same radius. Compared with the traditional spiral SDD, the SBA-SDD separates the spiral's functions of biasing adapter and the p-n junction definition. In this paper, the SBA-SDD is simulated using a Sentaurus TCAD tool, which is a full 3D device simulation tool. The simulated electric characteristics include electric potential, electric field, electron concentration, and single event effect. Because of the special design of the SBA-SDD, the SBA can generate an optimum drift electric field in the SDD, comparable with the conventional spiral SDD, while the SDD can be designed with concentric rings to reduce surface area. Also the current and heat generated in the SBA are separated from the SDD. To study the single event response, we simulated the induced current caused by incident heavy ions (20 and 50 μm penetration length) with different linear energy transfer (LET). The SBA-SDD can be used just like a conventional SDD, such as X-ray detector for energy spectroscopy and imaging, etc.

  8. Spiral CT venography in central venous obstruction

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Jin Wook; Park, Jae Hyung; Im, Jung Gi; Han, Moon Hee; Kim, In One; Chang, Kee Hyun; Yeon, Kyung Mo [Seoul National Univ. College of Medicine, Seoul (Korea, Republic of); Song, Chi Sung [Boramae Hospital, Seoul (Korea, Republic of)

    1998-11-01

    To determine the clinical usefulness of spiral computed tomographic (CT) venography for the evaluation of central venous obstruction. The authors prospectively performed a total of 29 spiral CT venography procedures in 25 consecutive patients with suspected central venous obstrucion. Diluted contrast media were directly injected into the peripheral veins of the hand or the foot. Scan parameters were 3mm X-ray beam collimation, table speed of 4-6cm/sec, scan time of 32-40sec, and injection delay of 20 sec. Axial images were reconstructed at 2-mm intervals, and using shaded surface display(SSD), maximum intensity projection(MIP), and multiplanar reformation(MPR), 3-D reconstruction was performed. In all cases, ascending venograp-hy(n=3D13) and/or direct catheter venography (n=3D21) was performed within 2 days of CT venography. With regard to site, extent, extent, severity, and cause of obstruction and collateral circulation, we compared the results of CT and contrast venography. In 24 patients, a total of 56 sites of central venous obstruction or stenosis (>50%) were demonstrated. The causes of obstruction were venous thrombosis(n=3D6), malignant tumors(n=3D4), arteriovenous fistula for hemodialysis(n=3D5), extrinsic compression(n=3D2), coincidence of extrinsic compression and arteriovenous fistula(n=3D1), pacemaker(n=3D1), mediastinal inflammatory pseudotumor(n=3D1), spinal tuberculosis(n=3D1), membranous obstruction of the hepatic inferior vena cava(n=3D1), Behcet's disease(n=3D1), or unknown cause(n=3D1). When compared with ascending venography(n=3D13), CT venography was superior for evaluation of the extent and cause of obstruction and collateral circulation in two, four and one case(s), respectively. For the evaluation of site and severity of obstruction, CT venography was equal to ascending venography. In two cases, direct catheter venography (n=3D21) was superior to CT venography for evaluating the obstruction site, but in three, five and one case

  9. BVRI Surface Photometry of Isolated Spiral Galaxies

    CERN Document Server

    Hernandez-Toledo, H; Avila-Reese, V

    2007-01-01

    A release of multicolor broad band (BVRI) photometry for a subsample of 44 isolated spirals drawn from the Catalogue of Isolated Galaxies (CIG) is presented. Total magnitudes and colors at various circular apertures, as well as some global structural/morphological parameters are estimated. Morphology is reevaluated through optical and sharp/filtered R band images, (B-I) color index maps, and archive near-IR JHK images from the Two-Micron Survey. The CAS structural parameters (Concentration, Asymmetry, and Clumpiness) were calculated from the images in each one of the bands. The fraction of galaxies with well identified optical/near-IR bars (SB) is 63%, while a 17% more shows evidence of weak or suspected bars (SAB). The sample average value of the maximum bar ellipticity is 0.4. Half of the galaxies in the sample shows rings. We identify two candidates for isolated galaxies with disturbed morphology. The structural CAS parameters change with the observed band, and the tendencies they follow with the morpholog...

  10. Application of 64 slice spiral CT in evaluating the patency of coronary artery after stent implantation

    Institute of Scientific and Technical Information of China (English)

    Yong-Shu Gao; Xing-Can Ma

    2015-01-01

    Objective:To explore the feasibility and effectiveness of 64 slice spiral CT in evaluating the patency of coronary artery after stent implantation.Methods:The 64 slice spiral CT image data of 125 patients after coronary artery stent implantation were collected, meanwhile, the image data of 25 patients underwent coronary angiography were also collected. The feasibility and accuracy of 64 slice spiral CT coronary artery stent imaging were comparatively analyzed. Results: The 64 slice spiral CT imaging quality with a stent diameter greater than 3.00 mm was significantly superior to that with a diameter of 2.25-3.00 mm. The CT imaging quality in the left main coronary artery and anterior descending artery was significantly higher than that in the left circumflex coronary artery. The CT imaging quality in the left main coronary artery was significantly higher than that in the right coronary artery. The CT reconstruction imaging quality in the drug coating stent was significantly superior to that in the bare metal stent. The sensitivity of 64 slice spiral CT was 100.00%, and the accuracy was 100.00%. In detecting the coronary artery with occlusion and stenosis (stent stenosis greater than 50%), the sensitivity was 90.00%, the false negative rate was 10.00%, and the positive predicative value was 100.00%.Conclusions:The effect of 64 slice spiral CT coronary imaging in evaluating the patency of coronary artery after stent implantation is highly consistent with that by coronary angiography, with a simple operation, less risk, and low cost, and thus, it can be completely taken as the imaging method in evaluating the patency of coronary artery after stent implantation.

  11. The DESIR Facility at SPIRAL2

    Indian Academy of Sciences (India)

    Bertram Blank; Desir

    2010-08-01

    The DESIR Collaboration proposes the construction of an experimental facility to exploit the low-energy beams from SPIRAL1, SPIRAL2 and S3. The high degree of purity required to push experiments towards the limits of stability will be achieved by the implementation in the SPIRAL2 production building of a high-efficiency RFQ cooler coupled to a high-resolution mass separator. Beams from the low-energy branch of the separator spectrometer S3 and from SPIRAL1 will allow complementary studies of refractory elements produced by means of fusion reactions as well as of light and intense exotic beams, respectively.

  12. Solvable Model of Spiral Wave Chimeras

    DEFF Research Database (Denmark)

    Martens, Erik Andreas; Laing, Carlo R.; Strogatz, Steven H.

    2010-01-01

    Spiral waves are ubiquitous in two-dimensional systems of chemical or biological oscillators coupled locally by diffusion. At the center of such spirals is a phase singularity, a topological defect where the oscillator amplitude drops to zero. But if the coupling is nonlocal, a new kind of spiral...... can occur, with a circular core consisting of desynchronized oscillators running at full amplitude. Here, we provide the first analytical description of such a spiral wave chimera and use perturbation theory to calculate its rotation speed and the size of its incoherent core....

  13. Type of spiral wave with trapped ions.

    Science.gov (United States)

    Li, Yuting; Li, Haihong; Zhu, Yun; Zhang, Mei; Yang, Junzhong

    2011-12-01

    Pattern formation in ultracold quantum systems has recently received a great deal of attention. In this work, we investigate a two-dimensional model system simulating the dynamics of trapped ions. We find a spiral wave that is rigidly rotating, but with a peculiar core region in which adjacent ions oscillate in antiphase. The formation of this spiral wave is ascribed to the excitability previously reported by Lee and Cross. The breakup of the spiral wave is probed and, especially, an extraordinary scenario of the disappearance of the spiral wave, caused by spontaneous expansion of the antiphase core, is unveiled.

  14. Evolution of Spiral Waves in Excitable Systems

    Institute of Scientific and Technical Information of China (English)

    KEN Ji-Rong; ZHU Tao; MO Shu-Fan

    2009-01-01

    Spiral waves, whose rotation center can be regarded as a point defect, widely exist in various two-dimensional excitable systems. In this paper, by making use of Duan's topological current theory, we obtain the charge density of spiral waves and the topological inner structure of its topological charge. The evolution of spiral wave is also studied from the topological properties of a two-dimensional vector field. The spiral waves are found generating or annihilating at the limit points and encountering, splitting, or merging at the bifurcation points of the two-dimensional vector field. Some applications of our theory are also discussed.

  15. 16层螺旋CT灌注成像鉴别诊断肺癌与肺良性肿物%Differential diagnosis of 16-slice spiral CT perfusion imaging in lung cancer and pulmonary benign masses

    Institute of Scientific and Technical Information of China (English)

    王海生; 韩艳平

    2014-01-01

    .8%misdiagnosis, misdiagnosis rate was 18.3%;BV and MTT moderate diagnostic sensitivity and speciifcity, the misdiagnosis rate was 10.7%and 11.3%, respectively, misdiagnosis rate was 9.9%and 10.3%;PS highest diagnostic sensitivity and speciifcity, misdiagnosis rate was 5.5%, 9.8%misdiagnosis rate, the parameter index was probably the best diagnostic indicators ROC. Conclusion The perfusion imaging of 16-slice spiral CT is helpful for the identiifcation of lung cancer and pulmonary benign masses.

  16. 肾癌高发人群正常肾脏MSCT灌注成像研究%A Study on Muti-slice Spiral Computed Tomography Perfusion Imaging in High Risk Normal Kidney

    Institute of Scientific and Technical Information of China (English)

    赵新宇; 董丹丹; 陈文军; 王恩峰; 程明

    2012-01-01

    Objective: To study the perfusion technique of MSCT and evaluate the primary application in 40-70 years normal kidney. Methods: The kidney non-enhenced imaging and perfusion imaging with 64-slice spiral CT were performed in 109 normal persons, aged 40-70 years. Perfusion parameters of renal, including blood flow (BF), blood volume(BV), mean transit time(MTT) and permeability surface(PS), were computed by Perfusion software. Results: Except MTT(P >0.05), perfusion parameters of the ipsilateral renal cortex and medulla all have significant differences(P 0.05), similarly for renal medulla. The same perfusion parameter of renal cortex between the male and female has no significant difference (P >0.05), similarly for renal medulla. Conclusions: MSCT perfusion techniques can not only show the morphologie changes of kidney, but also indicate the functional changes. The calculation of perfusion data are helpful for acknowledging its hemodynamic changes.%目的:探讨40-70岁肾癌高发人群正常肾脏MSCT灌注成像特征.方法:正常志愿者109例,采用64排多层螺旋CT对其肾脏进行平扫及灌注增强扫描,使用后处理renal tumor perfusion软件对图像进行后处理,得出正常肾脏皮髓质包括血流量(BF)、血容量(BV)、平均通过时间(MTT)及表面通透性(PS)四个灌注参数,比较同一灌注参数在皮髓质、左右侧及不同性别之间的差异.结果:受检对象除3例腹式呼吸明显,不能完成同层扫描外,其余106例均得到理想图像及数据,肾皮质与髓质BF值、BV值及PS值灌注参数值存在显著性差异(P值均<0.01),但肾皮质与髓质MTT值无显著性差异(P>0.05).左右侧皮质间及髓质间灌注参数无统计学差异(P>0.05).男女皮质间及髓质间灌注参数无统计学差异(P>0.05).结论:多层螺旋CT(MSCT)灌注成像在显示肾脏形态的同时,还可定量测量皮髓质的血流灌注情况,间接反映肾脏生理特征.

  17. MSCT灌注成像在肾细胞癌临床应用价值研究%The Value of Muti-slice Spiral Computed Tomography Perfusion Imaging in Diagnosis of Renal Cell Cancer

    Institute of Scientific and Technical Information of China (English)

    董丹丹; 赵新宇; 陈文军; 王恩峰; 程明

    2012-01-01

    目的:探讨肾细胞癌多层螺旋CT(MSCT)灌注成像特征,并研究其临床应用价值.方法:肾癌患者69例,采用64排多层螺旋CT对其肾脏进行平扫及灌注增强扫描,使用renal tumor perfusion软件对图像进行后处理,自动生成时间-密度曲线(TDC),各种灌注图像及感兴趣区(ROI)内的灌注参数,包括血流量(BF)、血容量(BV)、平均通过时间(MTT)及表面通透性(PS),将得到的灌注参数分别进行统计分析.结果:肾癌肿块灌注参数与已测得的正常肾皮质各灌注参数值均存在显著性差异(P值均<0.01),其中,正常肾皮质的BF值、BV值及PS值均高于肾癌组织,MTT值则相反;肾癌肿块灌注参数与已测得的正常肾髓质各灌注参数值同样存在显著性差异(p值均<0.01),正常肾髓质各灌注参数值均低于肾癌组织,而PS值二者之间差别不显著(P<0.05);肾癌患者健侧肾皮髓质灌注参数值与已测得的正常肾皮髓质各灌注参数值及肾癌患者癌旁正常肾皮髓质各灌注参数值,三者之间差异无统计学意义(P>0.05).结论:多层螺旋CT(MSCT)灌注成像在显示肾脏形态的同时,还可定量测量皮髓质的血流灌注情况,间接反映肾脏生理特征.%Objective: To study the perfusion technique of Multi-slice Sprial Computed Tomography (MSCT) and its clinical application in malignant kidney tumors. Methods: The kidney non-enhenced imaging and perfusion imaging with 64-slice spiral CT were performed in Sixty-eight cases of RCC (renal cell carcinoma). Perfusion parameters of renal including blood flow (BF), blood volume (BV), mean transit time(MTT) and permeability surface(PS )were computed by Perfusion software. Results: The same perfusion parameter between renal cortex and solid components of RCCs, have significant differences (P0.05). Conclusions: MSCT perfusion techniques can not only show the morphologie changes of the malignant tumors,but also indicate the functional changes of

  18. Neskinchenna spiral u seredovyshchi z vtratamy [The endless spiral in environment with losses

    Directory of Open Access Journals (Sweden)

    A. V. Talaluiev

    1998-09-01

    Full Text Available Found dispersion equation that describes the endless spiral of losses in the environment. The analytical expression for the wave resistance spiral, seen as a long line in lossy environment, and analytical expressions for the fields in cylindrical coordinates. The question of coordination sources of RF energy spiral.

  19. Elimination of Spiral Waves and Competition between Travelling Wave Impulses and Spiral Waves

    Institute of Scientific and Technical Information of China (English)

    YUAN Guo-Yong; ZHANG Guang-Cai; WANG Guang-Rui; CHEN Shi-Gang; SUN Peng

    2005-01-01

    @@ The interaction between travelling wave impulses and spiral waves is studied and the results of their competition are related to the exciting period. From the results, it is known that the formation and development of spiral waves in cardiac tissue depend on the period by which the travelling wave impulses are excited. A method is proposed to eliminate spiral waves, which is easily operated.

  20. Applications of NMR spectroscopy to systems biochemistry.

    Science.gov (United States)

    Fan, Teresa W-M; Lane, Andrew N

    2016-02-01

    The past decades of advancements in NMR have made it a very powerful tool for metabolic research. Despite its limitations in sensitivity relative to mass spectrometric techniques, NMR has a number of unparalleled advantages for metabolic studies, most notably the rigor and versatility in structure elucidation, isotope-filtered selection of molecules, and analysis of positional isotopomer distributions in complex mixtures afforded by multinuclear and multidimensional experiments. In addition, NMR has the capacity for spatially selective in vivo imaging and dynamical analysis of metabolism in tissues of living organisms. In conjunction with the use of stable isotope tracers, NMR is a method of choice for exploring the dynamics and compartmentation of metabolic pathways and networks, for which our current understanding is grossly insufficient. In this review, we describe how various direct and isotope-edited 1D and 2D NMR methods can be employed to profile metabolites and their isotopomer distributions by stable isotope-resolved metabolomic (SIRM) analysis. We also highlight the importance of sample preparation methods including rapid cryoquenching, efficient extraction, and chemoselective derivatization to facilitate robust and reproducible NMR-based metabolomic analysis. We further illustrate how NMR has been applied in vitro, ex vivo, or in vivo in various stable isotope tracer-based metabolic studies, to gain systematic and novel metabolic insights in different biological systems, including human subjects. The pathway and network knowledge generated from NMR- and MS-based tracing of isotopically enriched substrates will be invaluable for directing functional analysis of other 'omics data to achieve understanding of regulation of biochemical systems, as demonstrated in a case study. Future developments in NMR technologies and reagents to enhance both detection sensitivity and resolution should further empower NMR in systems biochemical research.

  1. Spiral 2 the scientific objectives

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2006-06-15

    The French ministry of research took the decision to build Spiral-2 in May 2005. Its construction costs are estimated to 130 million euros while its operating costs will near 8.5 million euros per year. The construction works will last 5 years. The Spiral-2 facility is based on a high power, superconducting driver Linac, which will deliver a high intensity, 40 MeV deuteron beam as well as a variety of heavy-ion beams with mass over charge ratio equal to 3 and energy up to 14.5 MeV/nucleon. Using a carbon converter, fast neutrons from the breakup of the 5 mA of deuterons impinging on a uranium carbide target will induce a rate of up to 10{sup 14} fissions/s. The radioactive ion beam intensities in the mass range from A = 60 to 140 will be of the order of 10{sup 6} to 10{sup 11} particles/s surpassing by one or two orders-of-magnitude any existing facility in the world. A direct irradiation of the UC{sub 2} target with {sup 3,4}He, {sup 6,7}Li or {sup 12}C may also be used. Different production targets will be used to produce high-intensity beams of light radioactive species with the Isol technique. The extracted radioactive ion beam will be accelerated to energies up to 20 MeV/nucleons by the existing Cime cyclotron. One of the most important features of the future Ganil accelerator complex will be the capability of delivering up to 5 stable or radioactive beams simultaneously in the energy range from the keV to several tens of MeV/nucleons. The document details also the future contribution of Spiral-2 concerning the structure of exotic nuclei, the thermodynamical aspects of nuclear matter, nucleosynthesis, the fundamental basic interactions, and the use of neutrons. (A.C.)

  2. Analysis of 16-Slice Spiral CT Perfusion Imaging in Lung Cancer and Benign Lung Tumor Differential Diagnosis Value%肺良恶性结节或肿块CT灌注研究

    Institute of Scientific and Technical Information of China (English)

    陈丽英

    2014-01-01

    Objective To Explore different benign and malignant pulmonary nodules or masses on CT perfusion characteristics, improve the level of differential diagnosis. Methods 110 cases of patients with lung diseases were retrospectively analyzed from May 2007 to May 2013 in our hospital, of whom were 50 cases of patients with lung cancer and 60 cases of patients with benign lung tumor. The two groups of patients lungs were scanned by applying PHILIPS BRILLIANCE 16-slice spiral CT and general of perfusion were analyzed by using CT perfusion pattern software package, and lesions perfusion values (PV), blood volume (BV), maximum enhancement value (PEI) and the time to peak (TTP) were measured and recorded. Results (1) There was statistically significant of PV, PEI and BV values between the highly-differentiated lung cancer group (n=24) and low, undifferentiated lung cancer group (n=26), but there was no significant difference of TTP between the two groups (P>0.05). (2) The differences of PV and PEI value were statistically significant between benign lung tumor group (n=60) and lung cancer (n=50) (P0.05); (3) squamous cell carcinoma group (n=28) and lung adenocarcinoma (n=22) PV, PEI , BV and TTP, the difference was not statistically significant (P>0.05);(4) central lung cancer group (n=21) and peripheral lung cancer group (n=29) PV, PEI, BV and TTP compared the difference was not statistically significant (P>0.05). Conclusion 16-slice spiral CT perfusion imaging can quantitatively reflect lung tumor blood supply relevant information, in favor of lung cancer and benign pulmonary nodules or lumps in the differential diagnosis in the differential diagnosis of higher value, worthy of promotion and application.%目的:探讨肺内不同良恶性结节或肿块的CT灌注特点,提高鉴别诊断水平。方法回顾性分析了2007年5月至2013年5月入住我院的110例肺部病变患者的临床资料,其中肺癌50例,肺良性肿物60例。应用PHILIPS BRILLIANCE 16

  3. Use of 64-slice Spiral CT Angiography of Renal Vein Imaging in Evaluating Renal Vein Abnor-malities%64层3DMSCT在肾静脉异常中的应用价值

    Institute of Scientific and Technical Information of China (English)

    侯伟伟; 王云华; 蒋中标; 郑凯

    2015-01-01

    【目的】探讨64层多排螺旋CT(MSCT)三维血管成像(3D MSCTA)在肾静脉中的诊断价值。【方法】收集拟行活体肾移植术供肾者96例,临床可疑胡桃夹综合征者5例,行64层3D M SC T A ,了解肾脏静脉血管起始、数目、分支走行及管径大小,进一步比较3D MSCTA各种图像后处理重建方法对肾静脉异常的显示效果。【结果】双肾静脉均为一支且其起源与走行正常者66例。肾静脉变异35例:包括2条右肾静脉者4例,3条右肾静脉者2例,主动脉后肾静脉者1例,肾静脉细小(考虑可疑胡桃夹综合征)者5例,性腺静脉和或腰静脉及左肾上腺静脉(左肾静脉常见属支)汇入左肾静脉主干者20例,2条左肾静脉者3例(2条肾静脉分别与腹主动脉前后分别汇入下腔静脉者1例;1条肾静脉汇入下腔静脉、一条肾静脉汇入半奇静脉者1例;1条肾静脉汇入下腔静脉、一条肾静脉汇入左髂总静脉者1例)。与手术所见完全一致者为99例,符合率为98%(99/101)。【结论】64层3D MSCTA结合适当的后处理重建方法可满意显示肾静脉正常解剖及变异情况,是评价各种肾静脉异常的准确、安全方法。%[Objective] To explore the use of 3‐dimensional 64‐slice Spiral computed tomography angiogra‐phy (3D MSCTA) in the diagnosis of renal veins .[Methods] A total of 96 cases of potential live renal donor and 5 cases of clinically diagnosed nut‐cracker sign (NCS) were examined by 64‐slice spiral computed tomo‐graphy angiography (CTA) .The origin ,number ,branch ,course and size of renal veins were observed .Fur‐ther comparisons were made for the capacities of deciphering renal vein abnormalities on all kinds of postpro‐cessing reconstruction images of 3D MSCT .[Results]Double renal vein with normal origins and courses were found in 66 cases .Among 35 cases of renal vein variation ,there were double right renal

  4. 正常胰腺不同部位的多层螺旋CT灌注成像研究%A study on multi-slice spiral CT perfusion imaging in different parts of normal pancreas

    Institute of Scientific and Technical Information of China (English)

    张喜荣; 黄小华; 董国礼; 张小明; 敬宗林; 郭静

    2012-01-01

    目的 应用多层螺旋CT灌注成像技术,探讨正常胰腺头、体和尾部的血流灌注特点.方法 选择临床行中上腹增强CT检查并符合正常胰腺纳入标准的患者35例,采用Toshiba Aquilion 16层螺旋CT先行平扫,在胰腺头、体和尾部显示完整的中心层面进行胰腺同层动态增强扫描,将扫描后所得影像数据传输到Vitrea 2.0后处理工作站,采用Toshiba体部灌注软件对正常胰腺各部位灌注参数做三点测量,其每部三点测量的平均值视为各部灌注参数最后值,并对各部灌注参数行统计学分析.结果 正常胰腺头部、体部和尾部的血流量(BF)、血容量(BV)、表面通透性(PS)和平均通过时间(MTT)的测量值分别为:头部(128.34±29.23) mL·100 g-1·min-1,(43.19±13.77) mL/100 g,(218.39±99.21) mL·100 g-1·min-1,(299.26±81.99)0.1 s;体部 (136.20±23.00) mL·100 g-1·min-1,(44.63±13.74) mL/100 g,(223.20±73.82) mL·100 g-1·min-1,(310.99±59.00) 0.1 s;尾部(128.04±27.67) mL·100 g-1·min-1,(46.04±20.14) mL/100 g,(232.24±76.65) mL·100 g-1·min-1,(299.96±71.45) 0.1 s.3组参数间均无统计学意义(P>0.05).结论 正常胰腺头部、体部和尾部供血动脉有所差异,但各部组织血流灌注基本一致.%Objective To explore the blood flow perfusion characteristics of different parts of normal pancreas by means of multi-slices spiral CT perfusion imaging. Methods Thirty-five patients without pancreatic disease,received contrast-enhanced CT exami-nation for the venter superior abdomen by 16-slice spiral CT. The completely displayed center level in the head,body and tail of nor-mal pancreas were examined by dynamic enhancement scanning. These data were processed on a Start Vitrea 2. 0 workstation by using Toshiba body software package. The three-point measurement approach was used to examin the parameters of blood flow (BF) ,blood volume (BV) ,permeability surface (PS) and mean transit time (MTT) of pancreatic tissues in

  5. Testing Density Wave Theory with Resolved Stellar Populations around Spiral Arms in M81

    CERN Document Server

    Choi, Yumi; Williams, Benjamin F; Weisz, Daniel R; Skillman, Evan D; Fouesneau, Morgan; Dolphin, Andrew E

    2015-01-01

    Stationary density waves rotating at a constant pattern speed $\\Omega_{\\rm P}$ would produce age gradients across spiral arms. We test whether such age gradients are present in M81 by deriving the recent star formation histories (SFHs) of 20 regions around one of M81's grand-design spiral arms. For each region, we use resolved stellar populations to determine the SFH by modeling the observed color-magnitude diagram (CMD) constructed from archival Hubble Space Telescope (HST) F435W and F606W imaging. Although we should be able to detect systematic time delays in our spatially-resolved SFHs, we find no evidence of star formation propagation across the spiral arm. Our data therefore provide no convincing evidence for a stationary density wave with a single pattern speed in M81, and instead favor the scenario of kinematic spiral patterns that are likely driven by tidal interactions with the companion galaxies M82 and NGC 3077.

  6. Vertical Scale Parameter Estimates for 48 Non-edge-on Spiral Galaxies

    Institute of Scientific and Technical Information of China (English)

    Jun Ma

    2003-01-01

    In the first paper of this series, we directly studied the mathematical forms, symmetry of spiral structure, and the projection of galactic discs on the images, and measured the pitch angles of the spiral arms and inclination angles of the galactic discs for 60 spiral galaxies. In this second paper, we estimate the vertical scale parameters of 48 non-edge-on spiral galaxies based on the method proposed by Peng et al. and on the results given in Paper I. As we know, for edge-on disc galaxies we can obtain the vertical scale parameter from the photometry, once a mathematical form is specified for the vertical light distribution. For non-edgeon galaxies, some other methods have to be used. The statistical result was that the vertical scale parameter is comparable for edge-on and non-edge-on galaxies,although it is obtained from two very different methods.

  7. Emergency Physicians Think in Spirals.

    Science.gov (United States)

    Renouf, Tia; Whalen, Desmond; Pollard, Megan; Dubrowski, Adam

    2015-11-17

    As adult learners, junior clerks on core rotations in emergency medicine (EM) are expected to "own" their patients and follow them from presentation to disposition in the Emergency Department (ED). Traditionally, we teach clerks to present an exhaustive linear list of symptoms and signs to their preceptors. This does not apply well to the fast-paced ED setting. Mnemonics have been developed to teach clerks how to present succinctly and cohesively. To address the need for continual patient reassessment throughout the patient's journey in the ED, we propose a complimentary approach called SPIRAL.

  8. Reconstruction and measurement of optic nerve sheath imaging in normal population with multi-slice spiral CT%正常人眶内段视神经的CT重建和参数测量

    Institute of Scientific and Technical Information of China (English)

    游勇; 成洪波; 樊宁; 王宁利; 杨洁; 刘璐; 刘旭阳

    2015-01-01

    Background Optical nerve damage of glaucomatous eyes is associated with intracranial pressure.Conventional method of evaluating intracranial pressure is to measure cerebrospinal pressure by lumber puncture.However,the measurement of intraorbital optical nerve parameters,a novel method of evaluating intracranial pressure,is introduced in this field.Objective This study was to measure and analyze the intraorbital optic nerve sheath diameter (ONSD) and cross sectional area (ONSA) in normal population using multi-slice spiral CT.Methods This study protocol was approved by Clinical Ethic Committee of Shenzhen Chinese Traditional Medical Hospital and followed Hersinki Declaration.Informed consent was obtained from each individual prior to any medical examination.One hundred and five eyes of 105 normal persons with normal cerebral CT image were enrolled in Shenzhen Chinese Traditional Medical Hospital from January 2012 to September 2013.Cerebral volume was scanned in all the individuals by 64 slice spiral CT.The brain images were obtained for the curve planar rebuilding of intraorbital optical nerve on image post-processing workstation.The maximum and minimum of ONSD and the ONSA in axial sections at 3,6,9,12 and 15 mm far away from globe wall were measured using a standardized technique to analyze the change of optical nerve parameters at different point locations.These parameters were compared in different gender or eyes.The correlation among age and the optical nerve parameters at 3 mm far away from globe wall was evaluated by multivariate regression analysis.Results The average maximal ONSDs were (6.24±0.47), (5.56±0.44),(5.18±0.43),(4.82±0.41) and (4.69±0.41) mm;the average minimal ONSDs were (5.56±0.50),(4.97± 0.41) ,(4.55±0.35),(4.26±0.39) and (4.10±0.40) mm;the average ONSAs were (27.68±4.40),(22.02±3.35) , (18.74± 2.75) , (16.34±2.72) , (15.40±2.68) mm2 at 3,6,9,12 and 15 mm far away from posterior eyeball wall,respectively, showing significant

  9. Chandra ACIS Observations of the Nearby Spiral Galaxy NGC 300

    Science.gov (United States)

    Bobar, Dale; Turner, Kevin; Schlegel, Eric M.

    2017-01-01

    The ACIS detector (Advanced CCD Imaging Spectrometer) onboard the Chandra X-ray Observatory has imaged the nearby spiral NGC 300 over three epochs for a total exposure of 1.885x102 ksec. We describe each observation as well as the merged data set. Each exposure contains 132 individual sources. We focus on the time variability and luminosity distributions of the sources. Initial results show no diffuse emissions in the galaxy. Finally, we compare the merged data set and the detected sources with other wavebands.

  10. NMR at 900 MHz

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    @@ An important factor in the development of solutionstate NMR has always been th e ability to produce stable and homogeneous magnetic fields. As higher and higher field strengths are reached the pressure is growing on manufacturers to produce NMR systems with greatly improved spectral resolution and signal to noise ratio. The introduction of the Varian 900 MHz INOVA system in August 2000 featuring Oxford Instruments 21.1 T magnet represents the latest pioneering development in NMR technology.

  11. Spiral density waves in M81. I. Stellar spiral density waves

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Chien-Chang; Lin, Lien-Hsuan; Wang, Hsiang-Hsu; Taam, Ronald E., E-mail: hhwang@asiaa.sinica.edu.tw [Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141, Taipei 10617, Taiwan, R.O.C (China)

    2014-04-20

    Aside from the grand-design stellar spirals appearing in the disk of M81, a pair of stellar spiral arms situated well inside the bright bulge of M81 has been recently discovered by Kendall et al. The seemingly unrelated pairs of spirals pose a challenge to the theory of spiral density waves. To address this problem, we have constructed a three-component model for M81, including the contributions from a stellar disk, a bulge, and a dark matter halo subject to observational constraints. Given this basic state for M81, a modal approach is applied to search for the discrete unstable spiral modes that may provide an understanding for the existence of both spiral arms. It is found that the apparently separated inner and outer spirals can be interpreted as a single trailing spiral mode. In particular, these spirals share the same pattern speed 25.5 km s{sup –1} kpc{sup –1} with a corotation radius of 9.03 kpc. In addition to the good agreement between the calculated and the observed spiral pattern, the variation of the spiral amplitude can also be naturally reproduced.

  12. ANGULAR-MOMENTUM IN BINARY SPIRAL GALAXIES

    NARCIS (Netherlands)

    OOSTERLOO, T

    1993-01-01

    In order to investigate the relative orientations of spiral galaxies in pairs, the distribution of the angle between the spin-vectors for a new sample of 40 binary spiral galaxies is determined. From this distribution it is found, contrary to an earlier result obtained by Helou (1984), that there is

  13. QS Spiral: Visualizing Periodic Quantified Self Data

    DEFF Research Database (Denmark)

    Larsen, Jakob Eg; Cuttone, Andrea; Jørgensen, Sune Lehmann

    2013-01-01

    In this paper we propose an interactive visualization technique QS Spiral that aims to capture the periodic properties of quantified self data and let the user explore those recurring patterns. The approach is based on time-series data visualized as a spiral structure. The interactivity includes ...

  14. Scaling effects in spiral capsule robots.

    Science.gov (United States)

    Liang, Liang; Hu, Rong; Chen, Bai; Tang, Yong; Xu, Yan

    2017-04-01

    Spiral capsule robots can be applied to human gastrointestinal tracts and blood vessels. Because of significant variations in the sizes of the inner diameters of the intestines as well as blood vessels, this research has been unable to meet the requirements for medical applications. By applying the fluid dynamic equations, using the computational fluid dynamics method, to a robot axial length ranging from 10(-5) to 10(-2) m, the operational performance indicators (axial driving force, load torque, and maximum fluid pressure on the pipe wall) of the spiral capsule robot and the fluid turbulent intensity around the robot spiral surfaces was numerically calculated in a straight rigid pipe filled with fluid. The reasonableness and validity of the calculation method adopted in this study were verified by the consistency of the calculated values by the computational fluid dynamics method and the experimental values from a relevant literature. The results show that the greater the fluid turbulent intensity, the greater the impact of the fluid turbulence on the driving performance of the spiral capsule robot and the higher the energy consumption of the robot. For the same level of size of the robot, the axial driving force, the load torque, and the maximum fluid pressure on the pipe wall of the outer spiral robot were larger than those of the inner spiral robot. For different requirements of the operating environment, we can choose a certain kind of spiral capsule robot. This study provides a theoretical foundation for spiral capsule robots.

  15. Tracing the spiral arms in IP Pegasi

    NARCIS (Netherlands)

    Baptista, R.; Morales-Rueda, L.; Harlaftis, E.T.; Marsh, T.R.; Steeghs, D.

    2005-01-01

    We report the analysis of time-resolved spectroscopy of IP Pegasi in outburst with eclipse mapping techniques to investigate the location and geometry of the observed spiral structures. We were able to obtain an improved view of the spiral structures with the aid of light curves extracted in

  16. Termination of pinned spirals by local stimuli

    Science.gov (United States)

    Chen, Jiang-Xing; Guo, Ming-Ming; Ma, Jun

    2016-02-01

    The termination of pinned spirals on a defect by means of local stimuli is studied. On a completely unexcitable defect, the elimination process is discussed and its corresponding mechanism is presented. Especially, the mechanism of unpinning spirals on a partially unexcitable defect, which has not been investigated so far, is explored. With fixed pacing frequency ω L , there exists a maximal radius R max above which the pinned spiral cannot be removed. It is found that the value of R max does not increase as ω L in a dynamical regime, forming a platform in the R\\textit{max}\\text-ωL curves. Based on analyzing the dispersion relation on the spiral tip around the obstacle, the underlying mechanism is clarified. Also, it is found that when multiple spirals are pinned, the value of R max decreases on a partially unexcitable defect while the change is very slight on a completely unexcitable one.

  17. Illusory spirals and loops in crystal growth.

    Science.gov (United States)

    Shtukenberg, Alexander G; Zhu, Zina; An, Zhihua; Bhandari, Misha; Song, Pengcheng; Kahr, Bart; Ward, Michael D

    2013-10-22

    The theory of dislocation-controlled crystal growth identifies a continuous spiral step with an emergent lattice displacement on a crystal surface; a mechanistic corollary is that closely spaced, oppositely winding spirals merge to form concentric loops. In situ atomic force microscopy of step propagation on pathological L-cystine crystals did indeed show spirals and islands with step heights of one lattice displacement. We show by analysis of the rates of growth of smaller steps only one molecule high that the major morphological spirals and loops are actually consequences of the bunching of the smaller steps. The morphology of the bunched steps actually inverts the predictions of the theory: Spirals arise from pairs of dislocations, loops from single dislocations. Only through numerical simulation of the growth is it revealed how normal growth of anisotropic layers of molecules within the highly symmetrical crystals can conspire to create features in apparent violation of the classic theory.

  18. Contrast enhanced two-phase spiral CT of urinary bladder

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jeung Uk; Cha, Seong Sook; Ryu, Ji Hwa; Oh, Jeong Geun; Chang, Seung Kuk; Choi, Seok Jin; Eun, Choong Kie [Inje Univ. College of Medicine, Pusan (Korea, Republic of); Seo, Chang Hye [Daedong General Hospital, Pusan (Korea, Republic of)

    1997-10-01

    To determine optimal scan time for the early phase of two-phase spiral CT and to evaluate its usefulness in the detection and assessment of extension of urinary bladder lesions. In four normal adults, we performed dynamic scanning and obtained time-density curves for internal and external iliac arteries and veins, and the wall of the urinary bladder. Sixty patients with 68 lesions of the urinary bladder or prostate underwent precontrast and two-phase spiral CT scanning. After injection of 100ml of noninonic contrast material, images for the early and delayed phases were obtained at 60 seconds and 5 minutes, respectively. We measured CT H. U. of the wall, the lesion, and lumen of urinary bladder as seen on axial scanning, in each image in which the lesion was best shown. For the detection of bladder lesions and assessment of their extension, precontrast, early-, and delayed phsed images were compared. Dynamic study of normal adults showed maximum enhancement of bladder wall between 60 and 100 seconds. The difference of CT H. U. between bladder wall and the lesion was greatest in the early phase. The best detection rate(98.5%) was seen during this phase, and for the detection of bladder lesion, this same phase was superior or equal (66/68, 97.1%) to the delayed phase. The precontrast image was also superior or equal (31/68, 45.6%) to that of the delayed phase. For the assessment of extension of bladder lesion, the early phase was superior (36/68, 52.9%) to the delayed phase, and precontrast image was superiour (1/68, 1.5%) to that of the delayed phase. For determining the stage of bladder cancer, the early phase was most accurate if the stages was below B{sub 2} or D, while for stage C, the delayed phase was most accurate. In two-hpase spiral CT scanning, we consider the optimal time for the early phase to be between 60 and 100 seconds after injection of contrast material. For the detection and assessment of extension of urinary bladder lesion, the early phase was

  19. Gd[sup 3+] chelates of interest in magnetic resonance imaging (MRI): studies using [sup 17]O NMR and EPR at several magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Hugh Powell, D. (Institute of Inorganic and Analytical Chemistry, University of Lausanne, Place du Chateau 3, CH-1005 Lausanne (Switzerland)); Gonzalez, Gabriel (Institute of Inorganic and Analytical Chemistry, University of Lausanne, Place du Chateau 3, CH-1005 Lausanne (Switzerland)); Tissieres, Veronique (Institute of Inorganic and Analytical Chemistry, University of Lausanne, Place du Chateau 3, CH-1005 Lausanne (Switzerland)); Micskei, Karoly (Institute of Inorganic and Analytical Chemistry, University of Lausanne, Place du Chateau 3, CH-1005 Lausanne (Switzerland) Institute of Inorganic and Analytical Chemistry, Kossuth University, 4010, Debrecen (Hungary)); Bruecher, Ernoe (Institute of Inorganic and Analytical Chemistry, Kossuth University, 4010, Debrecen (Hungary)); Helm, Lothar (Institute of Inorganic and Analytical Chemistry, University of Lausanne, Place du Chateau 3, CH-1005 Lausanne (Switzerland)); Merbach, Andre E. (Institute of Inorganic and Analytical Chemistry,

    1994-06-01

    The combination of [sup 17]O NMR relaxation rate and chemical shift measurements and EPR linewidth measurements at several magnetic fields provides a powerful probe of water exchange, rotational dynamics and electronic relaxation in aqueous solutions of Gd[sup 3+] complexes. This information is important for the understanding of the proton relaxivity of the complexes. Variable pressure measurements show a change of water exchange mechanism from associatively activated on [Gd(H[sub 2]O)[sub 8

  20. Shadows and spirals in the protoplanetary disk HD 100453

    Science.gov (United States)

    Benisty, M.; Stolker, T.; Pohl, A.; de Boer, J.; Lesur, G.; Dominik, C.; Dullemond, C. P.; Langlois, M.; Min, M.; Wagner, K.; Henning, T.; Juhasz, A.; Pinilla, P.; Facchini, S.; Apai, D.; van Boekel, R.; Garufi, A.; Ginski, C.; Ménard, F.; Pinte, C.; Quanz, S. P.; Zurlo, A.; Boccaletti, A.; Bonnefoy, M.; Beuzit, J. L.; Chauvin, G.; Cudel, M.; Desidera, S.; Feldt, M.; Fontanive, C.; Gratton, R.; Kasper, M.; Lagrange, A.-M.; LeCoroller, H.; Mouillet, D.; Mesa, D.; Sissa, E.; Vigan, A.; Antichi, J.; Buey, T.; Fusco, T.; Gisler, D.; Llored, M.; Magnard, Y.; Moeller-Nilsson, O.; Pragt, J.; Roelfsema, R.; Sauvage, J.-F.; Wildi, F.

    2017-01-01

    Context. Understanding the diversity of planets requires studying the morphology and physical conditions in the protoplanetary disks in which they form. Aims: We aim to study the structure of the 10 Myr old protoplanetary disk HD 100453, to detect features that can trace disk evolution and to understand the mechanisms that drive these features. Methods: We observed HD 100453 in polarized scattered light with VLT/SPHERE at optical (0.6 μm, 0.8 μm) and near-infrared (1.2 μm) wavelengths, reaching an angular resolution of 0.02'', and an inner working angle of 0.09''. Results: We spatially resolve the disk around HD 100453, and detect polarized scattered light up to 0.42'' ( 48 au). We detect a cavity, a rim with azimuthal brightness variations at an inclination of 38° with respect to our line of sight, two shadows and two symmetric spiral arms. The spiral arms originate near the location of the shadows, close to the semi major axis. We detect a faint feature in the SW that can be interpreted as the scattering surface of the bottom side of the disk, if the disk is tidally truncated by the M-dwarf companion currently seen at a projected distance of 119 au. We construct a radiative transfer model that accounts for the main characteristics of the features with an inner and outer disk misaligned by 72°. The azimuthal brightness variations along the rim are well reproduced with the scattering phase function of the model. While spirals can be triggered by the tidal interaction with the companion, the close proximity of the spirals to the shadows suggests that the shadows could also play a role. The change in stellar illumination along the rim induces an azimuthal variation of the scale height that can contribute to the brightness variations. Conclusions: Dark regions in polarized images of transition disks are now detected in a handful of disks and often interpreted as shadows due to a misaligned inner disk. However, the origin of such a misalignment in HD 100453, and

  1. Comparison of phase recovery methods in spiral speckle pattern interferometry correlation fringes

    Science.gov (United States)

    Vadnjal, Ana Laura; Etchepareborda, Pablo; Bianchetti, Arturo; Veiras, Francisco E.; Federico, Alejandro; Kaufmann, Guillermo H.

    2016-05-01

    Spiral interferometry can be used as a solution to the problem of sign ambiguity presented in the conventional speckle pattern interferometric technique when the optical phase needs to be reconstructed from a single closed fringe system. Depressions and elevations of the topography corresponding to the object deformation are distinguished by the direction of rotation of the local spiral fringe pattern. In this work, we implement and compare several methods for optical phase reconstruction by analyzing a single image composed of spiral speckle pattern interferometry correlation fringes. The implemented methods are based on contour line demodulation, center line demodulation, Spiral Phase Quadrature Transform and the 2D Riesz transform with multivector structure. Contour line and center line demodulation approaches are exclusively dedicated to images containing a fringe system with spiral structure. The others are based on the 2D Riesz transform, these being well known approaches in conventional interferometry. We examine simulated experiments and analyze some of the emerging drawbacks for solving the phase reconstruction problem by using different mean values of speckle size and background noise levels. We also discuss several numerical procedures that may well improve the efficiency and robustness of the presented numerical implementations. The performance of the implemented demodulation methods is evaluated by using a universal image quality index and therefore a quantitative comparison is also presented.

  2. Solar Interactions on Spiral Petroglyphs

    Science.gov (United States)

    Davis, Brian F.; Preston, Robert A.

    2003-11-01

    Like most prehistoric cultures, the ancestors of the native Puebloan people of the Southwest were aware of the yearly cycle of the sun. This and other natural phenomena are fundamental for interpreting their world view, religion, and art. Some researchers have argued that rock art, particularly petroglyphs, displays this focus on the natural world through the distinctive interplay of sunlight on these carvings. However, the question of whether or not these interactions occur by intention or chance has hampered the acceptance of this evidence by the archaeological community. To address this question we have performed a detailed study of a complete sample of over 100 spiral petroglyphs within a limited area (less than 20 km^2) of central New Mexico. We have examined this sample on both solstices and equinoxes, and have observed well-defined and consistent sunlight interactions on about 80This work clearly demonstrates the reality and profusion of this ancient cultural tradition. Several examples will be presented.

  3. NMR logging apparatus

    Energy Technology Data Exchange (ETDEWEB)

    Walsh, David O; Turner, Peter

    2014-05-27

    Technologies including NMR logging apparatus and methods are disclosed. Example NMR logging apparatus may include surface instrumentation and one or more downhole probes configured to fit within an earth borehole. The surface instrumentation may comprise a power amplifier, which may be coupled to the downhole probes via one or more transmission lines, and a controller configured to cause the power amplifier to generate a NMR activating pulse or sequence of pulses. Impedance matching means may be configured to match an output impedance of the power amplifier through a transmission line to a load impedance of a downhole probe. Methods may include deploying the various elements of disclosed NMR logging apparatus and using the apparatus to perform NMR measurements.

  4. NMR logging apparatus

    Science.gov (United States)

    Walsh, David O; Turner, Peter

    2014-05-27

    Technologies including NMR logging apparatus and methods are disclosed. Example NMR logging apparatus may include surface instrumentation and one or more downhole probes configured to fit within an earth borehole. The surface instrumentation may comprise a power amplifier, which may be coupled to the downhole probes via one or more transmission lines, and a controller configured to cause the power amplifier to generate a NMR activating pulse or sequence of pulses. Impedance matching means may be configured to match an output impedance of the power amplifier through a transmission line to a load impedance of a downhole probe. Methods may include deploying the various elements of disclosed NMR logging apparatus and using the apparatus to perform NMR measurements.

  5. NMR studies of metalloproteins.

    Science.gov (United States)

    Li, Hongyan; Sun, Hongzhe

    2012-01-01

    Metalloproteins represent a large share of the proteomes, with the intrinsic metal ions providing catalytic, regulatory, and structural roles critical to protein functions. Structural characterization of metalloproteins and identification of metal coordination features including numbers and types of ligands and metal-ligand geometry, and mapping the structural and dynamic changes upon metal binding are significant for understanding biological functions of metalloproteins. NMR spectroscopy has long been used as an invaluable tool for structure and dynamic studies of macromolecules. Here we focus on the application of NMR spectroscopy in characterization of metalloproteins, including structural studies and identification of metal coordination spheres by hetero-/homo-nuclear metal NMR spectroscopy. Paramagnetic NMR as well as (13)C directly detected protonless NMR spectroscopy will also be addressed for application to paramagnetic metalloproteins. Moreover, these techniques offer great potential for studies of other non-metal binding macromolecules.

  6. The Analysis of Blood Flow Dynamics About 64-slice Spiral CT Perfusion Imaging for Primary Liver Cancer%原发性肝癌患者64层螺旋CT灌注成像血流动力学分析

    Institute of Scientific and Technical Information of China (English)

    孙建华

    2015-01-01

    目的:探讨原发性肝癌患者64层螺旋CT灌注成像血流动力学的表现。方法收集2012年8月~2013年7月来我院就诊的确诊为原发性肝癌的患者46例并将其作为观察组,选取2012年8月~2013年7月来我院进行健康体检的健康对象46例并将其作为对照组,血液流动力学表现采用64层螺旋CT灌注成像观察,检测并比较两组患者肝动脉灌注量、肝门静脉灌注量、总肝灌注量、肝动脉灌注指数。结果观察组肝动脉灌注量、肝动脉灌注指数高于对照组,肝门静脉灌注量、总肝灌注量低于对照组,两组差异有统计学意义(P<0.05)。结论原发性肝癌患者采用64层螺旋CT灌注成像诊断血液流动力学表现较为显著,具有较高的诊断价值。%Objective To Einvestigate the blood flow dynamics about 64-slice spiral CT perfusion imaging for primary liver cancer. Methods 46 patients with primary liver cancer diagnosed in our hospital were collected from August 2012 to July 2013 and taken as the observation group, 46 cases of health object for physical examination in our hospital were selected at the same time as the control group, observed the blood lfow dynamics performance used by 64-slice spiral CT perfusion imaging, the two groups were measured and compared about hepatic arterial perfusion, hepatic portal vein perfusion, total liver perfusion, hepatic perfusion index. Results Hepatic arterial perfusion, hepatic perfusion index of observation group were higher, the hepatic portal vein perfusion, total hepatic perfusion were lower than the control group, the difference was statistically significant (P<0.05). Conclusions Primary liver cancer patients use 64-slice spiral CT perfusion imaging in the diagnosis of blood lfow dynamics performance is more signiifcant, with high diagnostic value.

  7. Turbulence and Star Formation in a Sample of Spiral Galaxies

    Science.gov (United States)

    Maier, Erin; Chien, Li-Hsin; Hunter, Deidre A.

    2016-11-01

    We investigate turbulent gas motions in spiral galaxies and their importance to star formation in far outer disks, where the column density is typically far below the critical value for spontaneous gravitational collapse. Following the methods of Burkhart et al. on the Small Magellanic Cloud, we use the third and fourth statistical moments, as indicators of structures caused by turbulence, to examine the neutral hydrogen (H i) column density of a sample of spiral galaxies selected from The H i Nearby Galaxy Survey. We apply the statistical moments in three different methods—the galaxy as a whole, divided into a function of radii and then into grids. We create individual grid maps of kurtosis for each galaxy. To investigate the relation between these moments and star formation, we compare these maps with their far-ultraviolet images taken by the Galaxy Evolution Explorer satellite.We find that the moments are largely uniform across the galaxies, in which the variation does not appear to trace any star-forming regions. This may, however, be due to the spatial resolution of our analysis, which could potentially limit the scale of turbulent motions that we are sensitive to greater than ∼700 pc. From comparison between the moments themselves, we find that the gas motions in our sampled galaxies are largely supersonic. This analysis also shows that the Burkhart et al. methods may be applied not just to dwarf galaxies but also to normal spiral galaxies.

  8. Vortices and spirals in the HD135344B transition disk

    CERN Document Server

    van der Marel, Nienke; Pinilla, Paola; Garufi, Antonio

    2016-01-01

    In recent years spiral structures have been seen in scattered light observations and signs of vortices in millimeter images of protoplanetary disks, both probably linked with the presence of planets. We present ALMA Band 7 (335 GHz or 0.89 mm) continuum observations of the transition disk HD135344B at unprecedented spatial resolution of 0.16", using superuniform weighting. The data show that the asymmetric millimeter dust ring seen in previous work actually consists of an inner ring and an outer asymmetric structure. The outer feature is cospatial with the end of one of the spiral arms seen in scattered light, but the feature itself is not consistent with a spiral arm due to its coradiance. We propose a new possible scenario to explain the observed structures at both wavelengths. Hydrodynamical simulations show that a massive planet can generate a primary vortex (which dissipates at longer timescales, becoming an axisymmetric ring) and trigger the formation of a second generation vortex further out. Within th...

  9. Three-dimensional spiral CT for neurosurgical planning

    Energy Technology Data Exchange (ETDEWEB)

    Klein, H.M. (Dept. of Neurosurgery, Technical Univ., Aachen (Germany)); Bertalanffy, H. (Dept. of Neurosurgery, Technical Univ., Aachen (Germany)); Mayfrank, L. (Dept. of Neurosurgery, Technical Univ., Aachen (Germany)); Thron, A. (Dept. of Neuroradiology, Technical Univ., Aachen (Germany)); Guenther, R.W. (Dept. of Diagnostic Radiology, Technical Univ., Aachen (Germany)); Gilsbach, J.M. (Dept. of Neurosurgery, Technical Univ., Aachen (Germany))

    1994-08-01

    We carried out 22 examinations to determine the value of three-dimensional (3D) volumetric CT (spiral CT) for planning neurosurgical procedures. All examinations were carried out on a of the first generation spiral CT. A tube model was used to investigate the influence of different parameter settings. Bolus injection of nonionic contrast medium was used when vessels or strongly enhancing tumours were to be delineated. 3D reconstructions were carried out using the integrated 3D software of the scanner. We found a table feed of 3 mm/s with a slice thickness of 2 mm and an increment of 1 mm to be suitable for most purposes. For larger regions of interest a table feed of 5 mm was the maximum which could be used without blurring of the 3D images. Particular advantages of 3D reconstructed spiral scanning were seen in the planning of approaches to the lower clivus, acquired or congenital bony abnormalities and when the relationship between vessels, tumour and bone was important. (orig.)

  10. Demonstration of pulmonary embolism with gadolinium-enhanced spiral CT

    Energy Technology Data Exchange (ETDEWEB)

    Coche, E.E.; Hammer, F.D.; Goffette, P.P. [Dept. of Radiology, St. Luc University Hospital, Brussels (Belgium)

    2001-11-01

    The authors report a case of successful detection of pulmonary embolism using gadolinium-enhanced spiral CT (Gadodiamide, 0.4 mmol/kg, 2 ml/s, delay 18 s) in a 77-year-old woman, with previous allergy to iodinated contrast medium, and renal failure, who presented with pulmonary arterial hypertension. Doppler ultrasound of the lower limbs was first performed and revealed a deep venous thrombosis of the right lower limb. To establish if venous thrombosis was the cause of pulmonary hypertension and to confirm that pulmonary endarterectomy was not indicated in this situation, several imaging modalities were performed. Lung scintigraphy and MRI were non-diagnostic. Gadolinium-enhanced spiral CT demonstrated a large thrombus located proximally and in a segmental artery of the right lower lobe. This case illustrates the potential usefulness of gadolinium as alternative contrast agent with spiral CT to diagnose pulmonary embolism and elucidate the cause of pulmonary arterial hypertension in a patient with some contraindications for iodinated contrast medium injection. (orig.)

  11. Directly observing continuum emission from self-gravitating spiral waves

    CERN Document Server

    Hall, Cassandra; Rice, Ken; Harries, Tim J; Klaassen, Pamela D; Biller, Beth

    2016-01-01

    We use a simple, self-consistent, self-gravitating semi-analytic disc model to conduct an examination of the parameter space in which self-gravitating discs may exist. We then use Monte-Carlo radiative transfer to generate synthetic ALMA images of these self-gravitating discs to determine the subset of this parameter space in which they generate non-axisymmetric structure that is potentially detectable by ALMA. Recently, several transition discs have been observed to have non-axisymmetric structure that extends out to large radii. It has been suggested that one possible origin of these asymmetries could be spiral density waves induced by disc self-gravity. We use our simple model to see if these discs exist in the region of parameter space where self-gravity could feasibly explain these spiral features. We find that for self-gravity to play a role in these systems typically requires a disc mass around an order of magnitude higher than the observed disc masses for the systems. The spiral amplitudes produced by...

  12. UC Merced NMR Instrumentation Acquisition

    Science.gov (United States)

    2015-06-18

    UC Merced NMR Instrumentation Acquisition For the UC Merced NMR Instrumentation Acquisition proposal, a new 400 MHz and an upgraded 500 MHz NMR ...UC Merced NMR Instrumentation Acquisition Report Title For the UC Merced NMR Instrumentation Acquisition proposal, a new 400 MHz and an upgraded 500...MHz NMR have been delivered, installed, and incorporated into research and two lab courses. While no results from these instruments have been

  13. Acute cholecystitis: two-phase spiral CT finding

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Eung Young; Yoon, Myung Hwan; Yang, Dal Mo; Chun Seok; Bae, Jun Gi; Kim, Hak Soo; Kim, Hyung Sik [Chungang Ghil Hospital, Incheon (Korea, Republic of)

    1998-07-01

    To describe the two-phase spiral CT findings of acute cholecystitis. Materials and Methods : CT scans of nine patients with surgically-proven acute cholecystitis were retrospectively reviewed for wall thickening, enhancement pattern of the wall, attenuation of the liver adjacent to the gallbladder, gallstones,gallbladder distension, gas collection within the gallbladder, pericholecystic fluid and infiltration of pericholecystic fat. Results : In all cases, wall thickening of the gallbladder was seen, though this was more distinct on delayed images, Using high-low-high attenuation, one layer was seen in five cases, nd three layers in four. On arterial images, eight cases showed transient focal increased attenuation of the liver adjacent to the gall bladder;four of these showed curvilinear attenuation and four showed subsegmental attenuation. One case showed curvilinear decreased attenuation between increased attenuation of the liver and the gallbladder, and during surgery, severe adhesion between the liver and gallbladder was confirmed. Additional CT findings were infiltration of pericholecystic fat (n=9), gallstones (n=7), gallbladder distension (n=6), pericholecystic fluid(n=3), and gas collection within the gallbladder (n=2). Conclusion : In patients with acute cholecystitis,two-phase spiral CT revealed wall thickening in one or three layers ; on delayed images this was more distinct. In many cases, arterial images showed transient focal increased attenuation of the liver adjacent to the gallbladder.

  14. 3D Reconstruction in Spiral Multislice CT Scans

    Directory of Open Access Journals (Sweden)

    M. Ghafouri

    2005-08-01

    Full Text Available Introduction & Background: The rapid development of spiral (helical computed tomography (CT has resulted in exciting new applications for CT. One of these applications, three-dimensional (3D CT with volume ren-dering, is now a major area of clinical and academic interest. One of the greatest advantages of spiral CT with 3D volume rendering is that it provides all the necessary information in a single radiologic study (and there-fore at the lowest possible price in cases that previously required two or more studies. Three-dimensional vol-ume rendering generates clinically accurate and immediately available images from the full CT data set with-out extensive editing. It allows the radiologist and clinician to address specific questions concerning patient care by interactively exploring different aspects of the data set. Three-dimensional images integrate a series of axial CT sections into a form that is often easier to interpret than the sections themselves and can be made to appear similar to other more familiar images such as catheter angiograms. The data are organized into a 3D matrix of volume elements (voxels. The screen of the computer monitor is a 2D-surface composed of discrete picture elements (pixels. Presenting what is stored in memory (ie, floating within the monitor on a 2D-screen is a challenge, but it is the very problem that 3D reconstruc-tion software has creatively solved. Voxel selection is usually accomplished by projecting lines (rays through the data set that correspond to the pixel matrix of the desired 2D image. Differences in the images produced with various 3D rendering techniques are the result of variations in how voxels are selected and weighted. In this article, I compare 3D volume rendering of spiral CT data with other rendering techniques (shaded surface display, maximum intensity projection and present a brief history of 3D volume rendering and discuss the im-plementation of this promising technology in terms of

  15. Experimental Study on Spiral Patterns in Dielectric Barrier Discharge System

    Institute of Scientific and Technical Information of China (English)

    LIU Shu-Hua; DONG Li-Fang; LIU Fu-Cheng; LI Shu-Feng; LI Xue-Chen; WANG Hong-Fang

    2006-01-01

    Spiral patterns are obtained in a dielectric barrier discharge system with water electrodes. The dynamics of spiral formation and transition is investigated. Wavelength characteristic of spiral patterns is also studied. Correlation measurements indicate that the wavelength of spiral pattern increases with the increasing gas gap width and oscillates with the increasing drive frequency.

  16. A Comparative Study of Knots of Star Formation in Interacting vs. Spiral Galaxies

    CERN Document Server

    Smith, Beverly J; Struck, Curtis; Olmsted, Susan; Jones, Keith

    2016-01-01

    Interacting galaxies are known to have higher global rates of star formation on average than normal galaxies, relative to their stellar masses. Using UV and IR photometry combined with new and published H-alpha images, we have compared the star formation rates of ~700 star forming complexes in 46 nearby interacting galaxy pairs with those of regions in 39 normal spiral galaxies. The interacting galaxies have proportionally more regions with high star formation rates than the spirals. The most extreme regions in the interacting systems lie at the intersections of spiral/tidal structures, where gas is expected to pile up and trigger star formation. Published Hubble Telescope images show unusually large and luminous star clusters in the highest luminosity regions. The star formation rates of the clumps correlate with measures of the dust attenuation, consistent with the idea that regions with more interstellar gas have more star formation. For the clumps with the highest star formation rates, the apparent dust a...

  17. Spiral Wave Dynamics in a Response System Subjected to a Spiral Wave Forcing

    Institute of Scientific and Technical Information of China (English)

    LI Guang-Zhao; CHEN Yong-Qi; TANG Guo-Ning; LIU Jun-Xian

    2011-01-01

    @@ Unidirectional linear error feedback coupling of two excitable medium systems displaying spiral waves is considered.The spiral wave in the response system is thus subjected to a spiral wave forcing.We find that the unidirectional feedback coupling can lead to richer behaviour than the mutual coupling.The spiral wave dynamics in the response system depends on the coupling strength and frequency mismatch.When the coupling strength is small, the feedback coupling induces the drift or meander of the forced spiral wave.When the coupling strength is large enough, the feedback coupling may lead to the transition from spiral wave to anti-target or target-like wave.The generation of anti-target wave in coupled excitable media is observed for the first time.Furthermore, when the coupling strength is strong, the synchronization between two subsystems can be established.%Unidirectional linear error feedback coupling of two excitable medium systems displaying spiral waves is considered. The spiral wave in the response system is thus subjected to a spiral wave forcing. We find that the unidirectional feedback coupling can lead to richer behaviour than the mutual coupling. The spiral wave dynamics in the response system depends on the coupling strength and frequency mismatch. When the coupling strength is small, the feedback coupling induces the drift or meander of the forced spiral wave. When the coupling strength is large enough, the feedback coupling may lead to the transition from spiral wave to anti-target or target-like wave. The generation of anti-target wave in coupled excitable media is observed for the first time. Furthermore,when the coupling strength is strong, the synchronization between two subsystems can be established.

  18. Visualization of Taylor-Couette and spiral Poiseuille flows using a snapshot FLASH spatial tagging sequence.

    Science.gov (United States)

    Moser, K W; Raguin, L G; Harris, A; Morris, H D; Georgiadis, J; Shannon, M; Philpott, M

    2000-02-01

    A new magnetic resonance imaging technique was applied to the Taylor-Couette and spiral Poiseuille (Taylor-Couette with superposed mean axial flux) flows for the first time. The experimental technique is a combination of spatial tagging methods and a snapshot FLASH imaging sequence, which allows the full-field visualization of 2-D slices of the flow field, with image acquisition times approximately half a second. By acquiring images every few seconds, direct visualization of flow patterns can be obtained in the form of cinematography. Tagged images of the Taylor-Couette flow were acquired in both the axial and transverse planes and confirmed previously reported numerical predictions of Taylor cell size. Tagged images of the spiral Poiseuille flows verified that the cells in this flow propagate at a higher velocity than the mean axial flow. In addition, intermittent cell formation was observed as the axial flow was increased.

  19. SPIRAL CONTACTOR FOR SOLVENT EXTRACTION COLUMN

    Science.gov (United States)

    Cooley, C.R.

    1961-06-13

    The patented extraction apparatus includes a column, perforated plates extending across the column, liquid pulse means connected to the column, and an imperforate spiral ribbon along the length of the column.

  20. Asymptotic theory for spiral wave reflections

    CERN Document Server

    Langham, Jacob; Barkley, Dwight

    2014-01-01

    Resonantly forced spiral waves in excitable media drift in straight-line paths, their rotation centers behaving as point-like objects moving along trajectories with a constant velocity. Interaction with medium boundaries alters this velocity and may often result in a reflection of the drift trajectory. Such reflections have diverse characteristics and are known to be highly non-specular in general. In this context we apply the theory of response functions, which via numerically computable integrals, reduces the reaction-diffusion equations governing the whole excitable medium to the dynamics of just the rotation center and rotation phase of a spiral wave. Spiral reflection trajectories are computed by this method for both small and large-core spiral waves. Such calculations provide insight into the process of reflection as well as explanations for differences in trajectories across parameters, including the effects of incidence angle and forcing amplitude. Qualitative aspects of these results are preserved fa...

  1. THE BIRTH AND DEATH PROCESSES OF HYPERCYCLE SPIRALS

    OpenAIRE

    KAZUMASA OIDA

    2003-01-01

    The behavior of hypercycle spirals in a two-dimensional cellular automaton model is analyzed. Each spiral can be approximated by an Archimedean spiral with center, width, and phase change according to Brownian motion. A barrier exists between two spirals if the phase synchronization hypothesis is taken into account, and the occurrence rate of pair decay (simultaneous disappearance of two spirals) can be explained through a random walk simulation with the barrier. Simulation experiments show t...

  2. 前庭导水管MSCT斜矢状位图像重建的研究%Study on the reconstruction of oblique sagittal images of multislice spiral CT for vestibular aqueduct

    Institute of Scientific and Technical Information of China (English)

    王帆; 靳激扬; 储成凤; 葛洪; 顾康康; 靳晶

    2016-01-01

    Objective To compare and analyze the full display rate for vestibular aqueduct ( VA) by a variety of MPR recon-struction methods withmultislice spiral CT so as to find VA best display image reconstruction method for VA as well as to obtain the range of normal value of VA diameter width ( MDVA) and width ( OMVA) .Methods MSCT scan data of temporal bone of individuals without obvious malformations of outside, middle and inner ear which were obtained from Tongren Hospital, Affiliated to Medical College of Southeast University, and Gulou Hospital, Affiliated to Medical College of Southeast University from 2010 to 2014, were retrospectively studied and those individuals were divided into infant group ( below nine years old) and adolescent and adult group ( over nine years old) , with 500 (1000 ears) in each group.The left and right ears were performed the MPR recon-structions of axial, sagittal, oblique standard of 15 degrees, 30 degrees, 45 degrees, 60 degrees,75 degrees sagittal and oblique sagittal plane parallel to the medial vestibular bone wall.The entire situation of VA was observed and the full display rate of VA was calculated.Finally, the eight methods for the whole disply of VA were evaluated to show whether there were differences in the display rate and the differences between different age groups were compared.The VA maximum diameter width and the normal value range of the width of the outer mouth were obtained in the reconstruction method with the highest display rate of VA.Results According to the above eight kinds of MPR reconstruction, the whole display of VA in the group of nine years old was as follow-ings:684 ears (347 right ears, left 337 ears);789 ears (387 right ears, left 402 ears);801 ears (398 right ears, left 402 ears);774 ears (385 right ears, left 389 ears);577 ears (290 right ears, left 287 ear), 284 ears (140 right ears and left 144 ears), 198 ears (right 95 ears, left 103 ears) 934 ears (469 right ears, left 465 ears), respectively

  3. Measurement of total lung capacity : a comparison of spiral CT and spirometry

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Kyung Il; Park, Kyung Ju; Lee, Eh Hyung; Yune, Heun Young; Suh, Jung Ho [Ajou Univ. School of Medicine, Suwon (Korea, Republic of); Choe, Kyu Ok; Lim, Tae Hwan [Yonsei Univ. College of Medicine, Seoul (Korea, Republic of); Chung, In Hyuk [Ulsan Univ. College of Medicine, Seoul (Korea, Republic of)

    1996-08-01

    To determine the potential of spiral CT as a functional imaging modality of the lung aside from its proven value in morphological depiction. Spiral CT scan was performed in ten normal female and nine normal male adults (mean age: 39, height: 163 cm, weight: 62 kg ) after single full breath-holding. Three dimensional lung images were reconstructed(minimal threshold value: -1,000HU, maximal threshold values: -150, 250, -350, -450 HU) to obtain total lung volume(TLV) on a histogram. Total lung volume measured by spiral CT was compared with TLV obtained by spirometry. Mean TLV measured by spirometry was 5.62L and TLV measured by CT at maximal threshold values of -150, -250, -350, and -450 HU was 5.53, 5.33, 5.15, and 4.98L, respectively. Mean absolute differences between the modalities of 0.17L(3%), 0.32L(5.6%), 0.48L(8.5%), 0.65L(11.5%) were statistically significant(p<0.001). Linear regression coefficients between the modalities were 0.99, 0.97, 095, and 0.94 and no statistically significant differences in accuracy of threshold levels in the estimation of lung volume(r=0.99, standard error=0.034L in all) were seen. TLV measured by spiral CT closely approximated that measured by spirometry. Spiral CT may be useful as a means of evaluating lung function.

  4. Discussion on Low Tension of Air of 16 Slice Spiral CT Three Phases Enhanced Images on the Application of Preoperative TNM Staging of Gastric Cancer%探讨低张充气16层螺旋CT三期增强扫描对胃癌术前TNM分期的应用

    Institute of Scientific and Technical Information of China (English)

    纪忠杰

    2014-01-01

    目的:探讨低张充气16层螺旋CT三期增强扫描对胃癌术前TNM分期的应用。方法选取我院82例胃癌患者,对其术前TNM分期进行低张充气16层螺旋CT三期增强扫描,并结合原始图像,分析其应用效果。结果82例患者在T分期的扫描准确率是63.42%,N分期扫描结果准确率是52.44%,M分期准确率是81.71%。结论低张充气16层螺旋CT三期增强扫描在患者术前TNM分期的诊断准确率较高,对临床确定手术方案具有重要指导意义。%Objective To investigate the 16 slice spiral CT hypotonic aeration three phase enhanced scan on the application of preoperative TNM staging of gastric cancer. Methods In our hospital in 82 cases of gastric cancer,the preoperative TNM staging of low tension of air 16 slice helical CT three phases enhanced images,and the combination of the original image,the analysis of its application effect. Results 82 patients in T stage scanning accuracy rate is 63.42%,the N staging scan results accuracy rate is 52.44%,the M staging accuracy rate is 81.71%. Conclusion 16 slice spiral CT hypotonic aeration three phase enhanced scanning in patients with preoperative TNM staging diagnosis accurate rate is higher, has the important guiding sense to the clinical determination of operation scheme.

  5. The (C II) 158 micron line mapping of spiral galaxies

    Science.gov (United States)

    Stacey, Gordon J.; Geis, N.; Genzel, Reinhard; Jackson, J. M.; Poglitsch, Albrecht; Townes, Charles H.

    1990-01-01

    Large scale maps of the face of spiral galaxies M51, M83, and NGC 6946 in the 158 micron (C II) fine structure line. The maps are obtained from the Far-infrared Imaging Fabry-Perot Interferometer (FIFI) during its first series of flights on board the Kuiper Airborne Observatory. The (C II) line emission is ubiquitous and easily traced over the mapped regions of each of the galaxies. The (C II) maps are compared with those obtained with similar sized beams in the CO line. The data available from these maps is interpreted.

  6. Petrophysical properties of greensand as predicted from NMR measurements

    DEFF Research Database (Denmark)

    Hossain, Zakir; Grattoni, Carlos A.; Solymar, Mikael

    2011-01-01

    ABSTRACT: Nuclear magnetic resonance (NMR) is a useful tool in reservoir evaluation. The objective of this study is to predict petrophysical properties from NMR T2 distributions. A series of laboratory experiments including core analysis, capillary pressure measurements, NMR T2 measurements...... and image analysis were carried out on sixteen greensand samples from two formations in the Nini field of the North Sea. Hermod Formation is weakly cemented, whereas Ty Formation is characterized by microcrystalline quartz cement. The surface area measured by the BET method and the NMR derived surface...... with macro-pores. Permeability may be predicted from NMR by using Kozeny's equation when surface relaxivity is known. Capillary pressure drainage curves may be predicted from NMR T2 distribution when pore size distribution within a sample is homogeneous....

  7. On Three-Dimensional Spiral Galaxies

    Institute of Scientific and Technical Information of China (English)

    LUO Xin-Lian; PENG Qiu-He; LONG Min; PENG Fang; ZOU Zhi-Gang

    2000-01-01

    Density waves in 3D spiral galaxies are studied. In order to eliminate the forbidden region near the corotation in the grand-design galaxies, we assume that the perturbation satisfies the stable condition Q(r) > 1 over all the disk except that at the corotation. Then, a new method is put forward here to determine some basic parameters of spiral galaxies. We apply it to our Galaxy, and the results are in good agreement with the previous results.

  8. View factors of cylindrical spiral surfaces

    Science.gov (United States)

    Lebedev, Vladimir A.; Solovjov, Vladimir P.

    2016-03-01

    Analytical expressions are presented for the view factors (radiative configuration factors) associated with the flat right cylindrical spiral surface. Such cylindrical spiral systems are widely applied as electrical resistance heating elements for lighting devices, electronic radio tubes, high-speed gas flow heaters, and other appliances used for scientific, industrial and domestic purposes. Derivation of the view factors is based on the invariant principles and the results presented in Lebedev (2000, 2003,1988) [1-3].

  9. Twisted Radiation by Electrons in Spiral Motion

    CERN Document Server

    Katoh, M; Mirian, N S; Konomi, T; Taira, Y; Kaneyasu, T; Hosaka, M; Yamamoto, N; Mochihashi, A; Takashima, Y; Kuroda, K; Miyamoto, A; Miyamoto, K; Sasaki, S

    2016-01-01

    We theoretically show that a single free electron in circular/spiral motion radiates an electromagnetic wave possessing helical phase structure and carrying orbital angular momentum. We experimentally demonstrate it by double-slit diffraction on radiation from relativistic electrons in spiral motion. We show that twisted photons should be created naturally by cyclotron/synchrotron radiations or Compton scatterings in various situations in astrophysics. We propose promising laboratory vortex photon sources in various wavelengths ranging from radio wave to gamma-rays.

  10. The distribution of prime numbers on the square root spiral

    CERN Document Server

    Hahn, Harry K

    2008-01-01

    Prime Numbers clearly accumulate on defined spiral graphs,which run through the Square Root Spiral. These spiral graphs can be assigned to different spiral-systems, in which all spiral-graphs have the same direction of rotation and the same -second difference- between the numbers, which lie on these spiral-graphs. A mathematical analysis shows, that these spiral graphs are caused exclusively by quadratic polynomials. For example the well known Euler Polynomial x2+x+41 appears on the Square Root Spiral in the form of three spiral-graphs, which are defined by three different quadratic polynomials. All natural numbers,divisible by a certain prime factor, also lie on defined spiral graphs on the Square Root Spiral (or Spiral of Theodorus, or Wurzelspirale). And the Square Numbers 4, 9, 16, 25, 36 even form a highly three-symmetrical system of three spiral graphs, which divides the square root spiral into three equal areas. Fibonacci number sequences also play a part in the structure of the Square Root Spiral. Wit...

  11. Detection of pulmonary nodules with breath-hold magnetic resonance imaging in comparison with computed tomography; Detektion von Lungenrundherden mit der Magnetresonanztomographie in Atemanhaltetechnik im Vergleich zur Spiral-Computertomographie

    Energy Technology Data Exchange (ETDEWEB)

    Schaefer, J.F.; Vollmar, J.; Seemann, M.D.; Kamm, P.; Erdtmann, B.; Claussen, C.D. [Abt. fuer Radiologische Diagnostik, Universitaetsklinikum Tuebingen (Germany); Schick, F. [Abt. fuer Radiologische Diagnostik, Sektion Experimentelle Radiologie, Universitaetsklinikum Tuebingen (Germany)

    2005-01-01

    Purpose: evaluation of sensitivity and false positive findings of two fast MRI sequences for the detection of pulmonary nodules in comparison with spiral CT by two independent observers. Materials and methods: all 30 enrolled patients had a spiral CT or MSCT as base line study. MRI was performed with a 1.5 T MR scanner (Sonata, Siemens) using a transverse 3D gradient echo sequence (3D-GRE: TR/TE/flip = 2.9 ms/1.1 ms/5 ) and a half-Fourier single-shot fast spin-echo sequence (HASTE: TR/TE/flip = 800/25/150 ) acquired in three planes. A separate analysis for both sequences was carried out prospectively by two independent readers (A and B) with different experience regarding pulmonary MRI. Additionally, a retrospective reading with knowledge of the CT scans was done. Results were calculated for all lesions and for lesions larger than 4 mm. Results: the sensitivities were 73%, 70% and 84% for the 3D-GRE sequence (reader A, reader B, retrospective reading) and 65%, 68% and 81% for the HASTE sequence. For lesions larger than 4 mm, the sensitivities were 93%, 89%, 96% for the 3D-GRE sequence and 85%, 85%, 96% for the HASTE sequence. The rate of false positive findings depended on the reader's experience, but was generally lower for the 3D-GRE sequence with 2 and 16 (reader A and B) false positive nodules compared to 4 and 40 false positive findings for the HASTE sequence. The 3D-GRE sequence was more accurate for both readers (reader A: p = 0.08, reader B: p = 0.00003). Conclusion: the sensitivity of MRI for the detection of lung nodules was only acceptable for lesions larger than 4 mm. The 3D-GRE sequence is superior to the HASTE sequence due to the reduced amount of false positive findings with comparable sensitivity. (orig.)

  12. Fast magnetohydrodynamic density waves in spiral galaxies

    Science.gov (United States)

    Lou, Yu-Qing; Han, J. L.; Fan, Zuhui

    1999-09-01

    The newly observed large-scale structures of a southern grand-design spiral galaxy NGC 2997 in total and polarized radio-continuum emission together with their overall correlations with the known optical spiral structure are physically interpreted in terms of fast magnetohydrodynamic (MHD) density waves in contrast to slow MHD density waves in NGC 6946. The global spiral pattern of such fast MHD density waves extends from the very centre, where the disc rotates almost rigidly within ~0.5arcmin, all the way to the outer disc with a more or less flat rotation curve. To strengthen the case, several known features of spiral galaxies M51 and IC 342 are referred to and their pattern identifications discussed. It is emphasized that the nature of a magnetized spiral galaxy would be much better appreciated by examining large-scale structures in optical, atomic hydrogen Hi, total and polarized radio-continuum and infrared emission together. As various star-formation processes occur concurrently and/or sequentially in spiral arms of high gas concentration, relatively broad and fuzzy Hi arms, roughly coincident with optical arms in the inner disc, are expected to extend from the extremities of fading optical arms further into the outer gas disc. We predict that the south-east `magnetic arm', apparently isolated from any optical features, in total and polarized radio-continuum intensity maps of NGC 2997 should be associated with an Hi gas arm yet to be detected in 21-cm line emission.

  13. Do Bars Drive Spiral Density Waves?

    CERN Document Server

    Buta, R J; Elmegreen, B G; Salo, H; Laurikainen, E; Elmegreen, D M; Puerari, I; Block, D L

    2009-01-01

    We present deep near-infrared K_s-band AAT IRIS2 observations of a selected sample of nearby barred spiral galaxies, including some with the strongest known bars. The sample covers a range of Hubble types from SB0- to SBc. The goal is to determine if the torque strengths of the spirals correlate with those of the bars, which might be expected if the bars actually drive the spirals as has been predicted by theoretical studies. This issue has implications for interpreting bar and spiral fractions at high redshift. Analysis of previous samples suggested that such a correlation exists in the near-infrared, where effects of extinction and star formation are less important. However, the earlier samples had only a few excessively strong bars. Our new sample largely confirms our previous studies, but still any correlation is relatively weak. We find two galaxies, NGC 7513 and UGC 10862, where there is a only a weak spiral in the presence of a very strong bar. We suggest that some spirals probably are driven by their ...

  14. Radial transport of dust in spiral galaxies

    CERN Document Server

    Vorobyov, E I; Shchekinov, Yu. A.

    2006-01-01

    Motivated by recent observations which detect dust at large galactocentric distances in the disks of spiral galaxies, we propose a mechanism of outward radial transport of dust by spiral stellar density waves. We consider spiral galaxies in which most of dust formation is localized inside the corotation radius. We show that in the disks of such spiral galaxies, the dust grains can travel over radial distances that exceed the corotation radius by roughly 25%. A fraction of the dust grains can be trapped on kidney-shaped stable orbits between the stellar spiral arms and thus can escape the destructive effect of supernova explosions. These grains form diffuse dusty spiral arms, which stretch 4-5 kpc from the sites of active star formation. About 10% of dust by mass injected inside corotation, can be transported over radial distances 3-4 kpc during approximately 1.0 Gyr. This is roughly an order of magnitude more efficient than can be provided by the turbulent motions.

  15. Benford distributions in NMR

    CERN Document Server

    Bhole, Gaurav; Mahesh, T S

    2014-01-01

    Benford's Law is an empirical law which predicts the frequency of significant digits in databases corresponding to various phenomena, natural or artificial. Although counter intuitive at the first sight, it predicts a higher occurrence of digit 1, and decreasing occurrences to other larger digits. Here we report the Benford analysis of various NMR databases and draw several interesting inferences. We observe that, in general, NMR signals follow Benford distribution in time-domain as well as in frequency domain. Our survey included NMR signals of various nuclear species in a wide variety of molecules in different phases, namely liquid, liquid-crystalline, and solid. We also studied the dependence of Benford distribution on NMR parameters such as signal to noise ratio, number of scans, pulse angles, and apodization. In this process we also find that, under certain circumstances, the Benford analysis can distinguish a genuine spectrum from a visually identical simulated spectrum. Further we find that chemical-sh...

  16. Comparison of parallel and spiral tagged MRI geometries in estimation of 3-D myocardial strains

    Science.gov (United States)

    Tustison, Nicholas J.; Amini, Amir A.

    2005-04-01

    Research involving the quantification of left ventricular myocardial strain from cardiac tagged magnetic resonance imaging (MRI) is extensive. Two different imaging geometries are commonly employed by these methodologies to extract longitudinal deformation. We refer to these imaging geometries as either parallel or spiral. In the spiral configuration, four long-axis tagged image slices which intersect along the long-axis of the left ventricle are collected and in the parallel configuration, contiguous tagged long-axis images spanning the width of the left ventricle between the lateral wall and the septum are collected. Despite the number of methodologies using either or both imaging configurations, to date, no comparison has been made to determine which geometry results in more accurate estimation of strains. Using previously published work in which left ventricular myocardial strain is calculated from 4-D anatomical NURBS models, we compare the strain calculated from these two imaging geometries in both simulated tagged MR images for which ground truth strain is available as well as in in vivo data. It is shown that strains calculated using the parallel imaging protocol are more accurate than that calculated using spiral protocol.

  17. Spiral 2: preliminary design study

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-11-15

    The scientific council of GANIL asked to perform a comparative study on the production methods based on gamma induced fission and rapid-neutron induced fission concerning the nature and the intensity of the neutron-rich products. The production rate expected should be around 10{sup 13} fissions per second. The study should include the implantation and the costs of the concerned accelerators. The scientific committee recommended also to study the possibility to re-inject the radioactive beams of SPIRAL-II in the cyclotrons available at GANIL in order to give access to an energy range from 1.7 to 100 MeV/nucleon. For that purpose, some study groups have been formed to evaluate the possibility of such a project in the different components: physics case, target-ion sources, drivers, post-acceleration and general infrastructure. The organization of the project study is given at the end of this report. The following report presents an overview of the study. Particularly the total costs have been assessed according to 3 options for the driver: 38.0*10{sup 6} euros for a 40 MeV deuteron linac, 18.7*10{sup 6} euros for a 45 MeV electron linac, and 29.1*10{sup 6} euros for a 80 MeV deuteron cyclotron.

  18. Spiral arms as cosmic ray source distributions

    Science.gov (United States)

    Werner, M.; Kissmann, R.; Strong, A. W.; Reimer, O.

    2015-04-01

    The Milky Way is a spiral galaxy with (or without) a bar-like central structure. There is evidence that the distribution of suspected cosmic ray sources, such as supernova remnants, are associated with the spiral arm structure of galaxies. It is yet not clearly understood what effect such a cosmic ray source distribution has on the particle transport in our Galaxy. We investigate and measure how the propagation of Galactic cosmic rays is affected by a cosmic ray source distribution associated with spiral arm structures. We use the PICARD code to perform high-resolution 3D simulations of electrons and protons in galactic propagation scenarios that include four-arm and two-arm logarithmic spiral cosmic ray source distributions with and without a central bar structure as well as the spiral arm configuration of the NE2001 model for the distribution of free electrons in the Milky Way. Results of these simulation are compared to an axisymmetric radial source distribution. Also, effects on the cosmic ray flux and spectra due to different positions of the Earth relative to the spiral structure are studied. We find that high energy electrons are strongly confined to their sources and the obtained spectra largely depend on the Earth's position relative to the spiral arms. Similar finding have been obtained for low energy protons and electrons albeit at smaller magnitude. We find that even fractional contributions of a spiral arm component to the total cosmic ray source distribution influences the spectra on the Earth. This is apparent when compared to an axisymmetric radial source distribution as well as with respect to the Earth's position relative to the spiral arm structure. We demonstrate that the presence of a Galactic bar manifests itself as an overall excess of low energy electrons at the Earth. Using a spiral arm geometry as a cosmic ray source distributions offers a genuine new quality of modeling and is used to explain features in cosmic ray spectra at the Earth

  19. STAR FORMATION IN THE OUTER DISK OF SPIRAL GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Barnes, Kate L.; Van Zee, Liese [Department of Astronomy, Indiana University, Bloomington, IN 47405 (United States); Cote, Stephanie [Canadian Gemini Office, Herzberg Institute of Astrophysics, National Research Council of Canada, Victoria (Canada); Schade, David, E-mail: barneskl@astro.indiana.edu, E-mail: vanzee@astro.indiana.edu, E-mail: Stephanie.Cote@nrc-cnrc.gc.ca, E-mail: David.Schade@nrc-cnrc.gc.ca [Herzberg Institute of Astrophysics, National Research Council of Canada, Victoria (Canada)

    2012-09-20

    We combine new deep and wide field of view H{alpha} imaging of a sample of eight nearby (d Almost-Equal-To 17 Mpc) spiral galaxies with new and archival H I and CO imaging to study the star formation and the star formation regulation in the outer disk. We find that, in agreement with previous studies, star formation in the outer disk has low covering fractions, and star formation is typically organized into spiral arms. The star formation in the outer disk is at extremely low levels, with typical star formation rate surface densities of {approx}10{sup -5} to 10{sup -6} M{sub Sun} yr{sup -1} kpc{sup -2}. We find that the ratio of the radial extent of detected H II regions to the radius of the H I disk is typically {approx}>85%. This implies that in order to further our understanding of the implications of extended star formation, we must further our understanding of the formation of extended H I disks. We measure the gravitational stability of the gas disk, and find that the outer gaseous disk is typically a factor of {approx}2 times more stable than the inner star-forming disk. We measure the surface density of outer disk H I arms, and find that the disk is closer to gravitational instability along these arms. Therefore, it seems that spiral arms are a necessary, but not sufficient, requirement for star formation in the outer disk. We use an estimation of the flaring of the outer gas disk to illustrate the effect of flaring on the Schmidt power-law index; we find that including flaring increases the agreement between the power-law indices of the inner and outer disks.

  20. A new method to estimate local pitch angles in spiral galaxies: Application to spiral arms and feathers in M81 and M51

    Energy Technology Data Exchange (ETDEWEB)

    Puerari, Ivânio [Instituto Nacional de Astrofísica, Optica y Electrónica, Calle Luis Enrique Erro 1, 72840 Santa María Tonantzintla, Puebla (Mexico); Elmegreen, Bruce G. [IBM T. J. Watson Research Center, 1101 Kitchawan Road, Yorktown Heights, New York 10598 (United States); Block, David L., E-mail: puerari@inaoep.mx [School of Computational and Applied Mathematics, University of Witwatersrand, Private Bag 3, WITS 2050 (South Africa)

    2014-12-01

    We examine 8 μm IRAC images of the grand design two-arm spiral galaxies M81 and M51 using a new method whereby pitch angles are locally determined as a function of scale and position, in contrast to traditional Fourier transform spectral analyses which fit to average pitch angles for whole galaxies. The new analysis is based on a correlation between pieces of a galaxy in circular windows of (lnR,θ) space and logarithmic spirals with various pitch angles. The diameter of the windows is varied to study different scales. The result is a best-fit pitch angle to the spiral structure as a function of position and scale, or a distribution function of pitch angles as a function of scale for a given galactic region or area. We apply the method to determine the distribution of pitch angles in the arm and interarm regions of these two galaxies. In the arms, the method reproduces the known pitch angles for the main spirals on a large scale, but also shows higher pitch angles on smaller scales resulting from dust feathers. For the interarms, there is a broad distribution of pitch angles representing the continuation and evolution of the spiral arm feathers as the flow moves into the interarm regions. Our method shows a multiplicity of spiral structures on different scales, as expected from gas flow processes in a gravitating, turbulent and shearing interstellar medium. We also present results for M81 using classical 1D and 2D Fourier transforms, together with a new correlation method, which shows good agreement with conventional 2D Fourier transforms.

  1. The use of spiral computed tomography in the localization of impacted maxillary canines

    Energy Technology Data Exchange (ETDEWEB)

    Preda, L.; La Fianza, A.; Di Maggio, E. [Pavia Univ. (Italy)

    1998-02-01

    The purpose was to compare spiral CT with conventional radiography in planning the orthodontic treatment of impacted permanent maxillary canines. In conclusion, CT facilitates the treatment of impacted canines especially when the teeth are very oblique to the arch. Root resorption is better demonstrated especially on the palatal and buccal surfaces of the adjacent incisors. Spiral CT reduces examination time and risks of accidental movement, thus optimizing multiplanar quality. Examination at 2:1 pitch enables a significant reduction in radiation exposure without loss of image quality. (N.C.)

  2. Compare and Research the Radiation dose and Image Quality on Dual Energy Dual Source Spiral CT Pulmonary Artery Imaging%双源双能量螺旋CT肺动脉成像辐射剂量与图像质量的对比研究

    Institute of Scientific and Technical Information of China (English)

    张筱双

    2015-01-01

    Objective To compare the difference of the radiation dose and image quality on dual energy dual source spiral CT pulmonary artery imaging.Methods 80 cases of pulmonary embolism patients in our hospital were selected as the research object. All patients were willing to accept CTPA examination, 40 cases in each group. A group used tube voltage 80/Sn140KV check, B group used tube voltage 100/Sn140KV examination, compared two groups’ pulmonary artery, pulmonary artery, the dorsal fat CT value, other indicators and CT image treatment subjective evaluation, calculation of signal to noise ratio (SNR), contrast to noise ratio (CNR) and effective dose (ED).Results The average CT value of A group’s pulmonary artery, mean CNR index were signiifcantly higher than those of group B(P<0.05), subjective CT image quality evaluation results show score were not signiifcantly different between A group and B group, but ed level of group A was signiifcantly lower than that of group B(P<0.05).Conclusion Dual source dual energy CT pulmonary artery imaging using scanning 80/Sn140 kV has high value in the diagnosis of CT images at the same time, and can greatly reduce the radiation dose during examination, which has clinical application and popularization value.%目的:对比第二代双源双能量螺旋CT肺动脉成像(CTPA)不同辐射剂量下CT图像质量的差异性。方法筛选我院收治的肺栓塞患者80例,作为研究对象。所有患者均自愿接受CTPA检查,每组40例,其中A组管电压80/Sn140KV检查,B组管电压100/Sn140KV检查,比较两组患者肺动脉主干、肺动脉段、背部脂肪CT值等指标,并对CT影像治疗进行主观评分,计算信噪比(SNR)、对比噪声比(CNR)、有效剂量(ED)等。结果 A组患者肺动脉平均CT值、平均CNR指标明显高于B组(P<0.05),主观CT影像质量评价结果显示A组与B组评分无显著差异,但A组ED水平明显低于B组(P<0.05)。结论

  3. Analysis of multi-slice spiral CT images in patients with esophageal cancer after surgery or radiotherapy%食管癌患者术后或放疗后多排螺旋 CT 影像分析

    Institute of Scientific and Technical Information of China (English)

    王锋

    2016-01-01

    Objective To explore the application value of multi-detector row spiral CT after the operation or radiotherapy in patients with esophageal carcinoma .Methods From August 2014 to March 2015,23 patients with esophageal cancer treated in our hospital received the examination of multi-detector row spiral CT after the operation or radiotherapy .Results After operation,CT re-sults showed that there were 4 cases with postoperative lymph node metastasis ,2 with lung metastasis and 3 with bone metastases ,2 with pericardial effusion ,1 with pleural effusion ,1 with esophageal mediastinum fistula and 1 with anastomotic recurrence .CT results also showed that after radiotherapy there were 12 with lymph node metastasis ,2 with liver metastasis ,3 with lung metastasis ,1 with radioac-tive pneumonia and 2 with pleural effusion .Conclusion The multi-slice helical CT can display a number of clinical manifestations such as complications ,recurrence and metastasis after operation and radiotherapy .It has an important clinical value .%目的:探讨多排螺旋CT在食管癌患者术后或放疗中的应用价值。方法2014年8月至2015年3月我院收治的23例食管癌患者,术后或放疗后均行多部位多排螺旋CT检查。结果 CT结果显示:术后患者出现淋巴结转移4例,肺部转移2例,骨转移3例,心包积液2例,胸腔积液1例,食管纵膈瘘1例,吻合口复发1例;而放疗后患者出现淋巴结转移12例,肝脏转移2例,肺部转移3例,放射性肺炎1例,胸腔积液2例。结论多排螺旋CT可显示出食管癌患者术后或放疗后的并发症、复发及转移等临床表现,具有重要的临床应用价值。

  4. 64 Slice Spiral CT and Mammography for the Diagnosis of Comparative Study of Breast Carcinoma in Imaging%64排螺旋CT与钼靶摄影在影像诊断乳腺癌中的对比研究

    Institute of Scientific and Technical Information of China (English)

    赵宝贵

    2014-01-01

    Objective To explore the application value of multislice spiral CT and mammography in the diagnosis of breast cancer. Methods Retrospective analysis of the 60 cases of breast cancer confirmed by pathology and plain scan, enhanced and image reconstruction. Results In 60 cases of breast cancer were mass type,57 cases showed irregular shape,48 cases of edge see burr,8 cases of skin changes,4 cases of skin retraction,surrounding invasion in 12 cases, axillary lymph nodes seen in 32 cases,mediastinal lymph nodes and lung metastasis. Enhanced masses enhanced obviously, the increase of CT value (18~83) Hu,parallel reconstruction makes mass surrounding structure is stereoscopic display. Conclusion Multi slice spiral CT examination has certain application value in the diagnosis of breast cancer.%目的:探讨多层螺旋 CT 及钼靶摄影在乳腺癌诊断中的应用价值。方法回顾性分析经病理证实的60例乳腺癌平扫,增强及重建图像。结果60例乳腺癌均为肿块型,57例表现为不规则形,48例边缘见毛刺,8例皮肤改变,4例皮肤内陷,周围侵犯12例,32例见腋窝淋巴结,纵隔淋巴结及肺内转移。增强后肿块强化明显,CT 值升高(18~83)hu,并行重建使肿块周边结构呈立体显示。结论多层螺旋 CT 检查在乳腺癌定性诊断中有一定的应用价值。

  5. Spiral Tomography for Determining Implant Angulation: An In Vitro Study

    Directory of Open Access Journals (Sweden)

    Z. Dalili Kajan

    2008-06-01

    Full Text Available Objective: To study the accuracy of spiral tomography in the determination of implant angulation.Materials and Methods: Eighteen gutta-percha filled points on dry mandibles were se-lected for implant placement. A translucent acrylic template was fabricated for each man-dible. After preparing tomographic images (2 mmslice thickness, Cranex Tome, the ideal axis of the implant was traced. The angle between the ideal axis and the tangent line on the alveolar crest in the buccal side was measured and transferred to aluminum sleeves by a protractor. After implant placement, tomographic images were taken again and angles of the actual implants were estimated. In addition, thedistances from the tip of the actual and the supposed implants to the buccal cortex were measured. The data were analyzed by paired sample t test with 95% confidence.Results: Less than two-degreedifference between angles of the supposed and the actual implants was found in 44.4% of the cases, whilst 33.3% revealed more than five-degreedifference. There was a significant statistical difference between the angle of the actual and the supposed implants. There was also a significant statistical difference between the linear distances from the tip of the actual and the supposed implants to buccal cortex(P=0.015Conclusion: Spiral tomography in combination with template may provide acceptable re-sults concerning implant angulation and prediction of cortical perforation risk.

  6. Spiral CT of Non-Graft Post Cardiac Surgery Complications: A Pictorial Essay

    Directory of Open Access Journals (Sweden)

    S. Shirani

    2010-06-01

    Full Text Available Spiral CT is a rapidly growing method for noninvasive visualization of post-operative complications, including post-operative complications in CABG (coronary artery bypass graft. In the recent years, several different, yet more efficient types have been introduced with progressive improvement in the diagnostic accuracy in the detection of post-operative complications. The introduction of 64-slice technology, which allows high resolution as well as reconstructed images, has resulted in further progress in the diagnostic process. This kind of diagnostic equipment will spread rapidly in the world. Although studies with large numbers of patients regarding spiral CT as a routine diagnostic method have not been reported, there is great need for it all over the world. In this article, we intend to review the spiral CT findings of non-graft complications in patients after cardiac surgery.

  7. Coarse-scale biases for spirals and orientation in human visual cortex.

    Science.gov (United States)

    Freeman, Jeremy; Heeger, David J; Merriam, Elisha P

    2013-12-11

    Multivariate decoding analyses are widely applied to functional magnetic resonance imaging (fMRI) data, but there is controversy over their interpretation. Orientation decoding in primary visual cortex (V1) reflects coarse-scale biases, including an over-representation of radial orientations. But fMRI responses to clockwise and counter-clockwise spirals can also be decoded. Because these stimuli are matched for radial orientation, while differing in local orientation, it has been argued that fine-scale columnar selectivity for orientation contributes to orientation decoding. We measured fMRI responses in human V1 to both oriented gratings and spirals. Responses to oriented gratings exhibited a complex topography, including a radial bias that was most pronounced in the peripheral representation, and a near-vertical bias that was most pronounced near the foveal representation. Responses to clockwise and counter-clockwise spirals also exhibited coarse-scale organization, at the scale of entire visual quadrants. The preference of each voxel for clockwise or counter-clockwise spirals was predicted from the preferences of that voxel for orientation and spatial position (i.e., within the retinotopic map). Our results demonstrate a bias for local stimulus orientation that has a coarse spatial scale, is robust across stimulus classes (spirals and gratings), and suffices to explain decoding from fMRI responses in V1.

  8. Observational Confirmations of Spiral Density Wave Theory

    Science.gov (United States)

    Kennefick, Julia D.; Kennefick, Daniel; Shameer Abdeen, Mohamed; Berrier, Joel; Davis, Benjamin; Fusco, Michael; Pour Imani, Hamed; Shields, Doug; DMS, SINGS

    2017-01-01

    Using two techniques to reliably and accurately measure the pitch angles of spiral arms in late-type galaxies, we have compared pitch angles to directly measured black hole masses in local galaxies and demonstrated a strong correlation between them. Using the relation thus established we have developed a pitch angle distribution function of a statistically complete volume limited sample of nearby galaxies and developed a central black hole mass function for nearby spiral galaxies.We have further shown that density wave theory leads us to a three-way correlation between bulge mass, pitch angle, and disk gas density, and have used data from the Galaxy Disk Mass Survey to confirm this possible fundamental plane. Density wave theory also predicts that the pitch angle of spiral arms should change with observed waveband as each waveband is sampling a different stage in stellar population formation and evolution. We present evidence that this is indeed the case using a sample of galaxies from the Spitzer Infrared Nearby Galaxy Survey. Furthermore, the evolved spiral arms cross at the galaxy co-rotation radius. This gives a new method for determining the co-rotation radius of spiral galaxies that is found to agree with those found using previous methods.

  9. Spiral Arms as Cosmic Ray Source Distributions

    CERN Document Server

    Werner, M; Strong, A W; Reimer, O

    2014-01-01

    There is evidence that the distribution of suspected cosmic ray sources are associated with the spiral arm structure of galaxies. It is yet not clearly understood what effect such a cosmic ray source distribution has on the particle transport in our Galaxy. We use the PICARD code to perform high-resolution 3D simulations of electrons and protons in galactic propagation scenarios that include four-arm and two-arm logarithmic spiral cosmic ray source distributions with and without a central bar structure as well as the spiral arm configuration of the NE2001 model for the distribution of free electrons in the Milky Way. Results of these simulation are compared to an axisymmetric radial source distribution. Also, effects on the cosmic ray flux and spectra due to different positions of the Earth relative to the spiral structure are studied. We find that high energy electrons are strongly confined to their sources and the obtained spectra largely depend on the Earth's position relative to the spiral arms. Similar f...

  10. Teaching NMR Using Online Textbooks

    Directory of Open Access Journals (Sweden)

    Joseph P. Hornak

    1999-12-01

    Full Text Available Nuclear magnetic resonance (NMR spectroscopy has almost become an essential analytical tool for the chemist. High-resolution one- and multi-dimensional NMR, timedomain NMR, and NMR microscopy are but a few of the NMR techniques at a chemist's disposal to determine chemical structure and dynamics. Consequently, even small chemistry departments are finding it necessary to provide students with NMR training and experience in at least some of these techniques. The hands-on experience is readily provided with access to state-of-the-art commercial spectrometers. Instruction in the principles of NMR is more difficult to achieve as most instructors try to teach NMR using single organic or analytical chemistry book chapters with static figures. This paper describes an online textbook on NMR spectroscopy called The Basics of NMR (http://www.cis.rit.edu/htbooks/nmr/ suitable for use in teaching the principles of NMR spectroscopy. The book utilizes hypertext and animations to present the principles of NMR spectroscopy. The book can be used as a textbook associated with a lecture or as a stand-alone teaching tool. Conference participants are encouraged to review the textbook and evaluate its suitability for us in teaching NMR spectroscopy to undergraduate chemistry majors.

  11. Compressed sensing reconstruction of cardiac cine MRI using golden angle spiral trajectories

    Science.gov (United States)

    Tolouee, Azar; Alirezaie, Javad; Babyn, Paul

    2015-11-01

    In dynamic cardiac cine Magnetic Resonance Imaging (MRI), the spatiotemporal resolution is limited by the low imaging speed. Compressed sensing (CS) theory has been applied to improve the imaging speed and thus the spatiotemporal resolution. The purpose of this paper is to improve CS reconstruction of under sampled data by exploiting spatiotemporal sparsity and efficient spiral trajectories. We extend k-t sparse algorithm to spiral trajectories to achieve high spatio temporal resolutions in cardiac cine imaging. We have exploited spatiotemporal sparsity of cardiac cine MRI by applying a 2D + time wavelet-Fourier transform. For efficient coverage of k-space, we have used a modified version of multi shot (interleaved) spirals trajectories. In order to reduce incoherent aliasing artifact, we use different random undersampling pattern for each temporal frame. Finally, we have used nonuniform fast Fourier transform (NUFFT) algorithm to reconstruct the image from the non-uniformly acquired samples. The proposed approach was tested in simulated and cardiac cine MRI data. Results show that higher acceleration factors with improved image quality can be obtained with the proposed approach in comparison to the existing state-of-the-art method. The flexibility of the introduced method should allow it to be used not only for the challenging case of cardiac imaging, but also for other patient motion where the patient moves or breathes during acquisition.

  12. Compressed sensing reconstruction of cardiac cine MRI using golden angle spiral trajectories.

    Science.gov (United States)

    Tolouee, Azar; Alirezaie, Javad; Babyn, Paul

    2015-11-01

    In dynamic cardiac cine Magnetic Resonance Imaging (MRI), the spatiotemporal resolution is limited by the low imaging speed. Compressed sensing (CS) theory has been applied to improve the imaging speed and thus the spatiotemporal resolution. The purpose of this paper is to improve CS reconstruction of under sampled data by exploiting spatiotemporal sparsity and efficient spiral trajectories. We extend k-t sparse algorithm to spiral trajectories to achieve high spatio temporal resolutions in cardiac cine imaging. We have exploited spatiotemporal sparsity of cardiac cine MRI by applying a 2D+time wavelet-Fourier transform. For efficient coverage of k-space, we have used a modified version of multi shot (interleaved) spirals trajectories. In order to reduce incoherent aliasing artifact, we use different random undersampling pattern for each temporal frame. Finally, we have used nonuniform fast Fourier transform (NUFFT) algorithm to reconstruct the image from the non-uniformly acquired samples. The proposed approach was tested in simulated and cardiac cine MRI data. Results show that higher acceleration factors with improved image quality can be obtained with the proposed approach in comparison to the existing state-of-the-art method. The flexibility of the introduced method should allow it to be used not only for the challenging case of cardiac imaging, but also for other patient motion where the patient moves or breathes during acquisition.

  13. Feasibility of high-resolution one-dimensional relaxation imaging at low magnetic field using a single-sided NMR scanner applied to articular cartilage

    Science.gov (United States)

    Rössler, Erik; Mattea, Carlos; Stapf, Siegfried

    2015-02-01

    Low field Nuclear Magnetic Resonance increases the contrast of the longitudinal relaxation rate in many biological tissues; one prominent example is hyaline articular cartilage. In order to take advantage of this increased contrast and to profile the depth-dependent variations, high resolution parameter measurements are carried out which can be of critical importance in an early diagnosis of cartilage diseases such as osteoarthritis. However, the maximum achievable spatial resolution of parameter profiles is limited by factors such as sensor geometry, sample curvature, and diffusion limitation. In this work, we report on high-resolution single-sided NMR scanner measurements with a commercial device, and quantify these limitations. The highest achievable spatial resolution on the used profiler, and the lateral dimension of the sensitive volume were determined. Since articular cartilage samples are usually bent, we also focus on averaging effects inside the horizontally aligned sensitive volume and their impact on the relaxation profiles. Taking these critical parameters into consideration, depth-dependent relaxation time profiles with the maximum achievable vertical resolution of 20 μm are discussed, and are correlated with diffusion coefficient profiles in hyaline articular cartilage in order to reconstruct T2 maps from the diffusion-weighted CPMG decays of apparent relaxation rates.

  14. SpArcFiRe: Scalable Automated Detection of Spiral Galaxy Arm Segments

    Science.gov (United States)

    Davis, Darren R.; Hayes, Wayne B.

    2014-08-01

    Given an approximately centered image of a spiral galaxy, we describe an entirely automated method that finds, centers, and sizes the galaxy (possibly masking nearby stars and other objects if necessary in order to isolate the galaxy itself) and then automatically extracts structural information about the spiral arms. For each arm segment found, we list the pixels in that segment, allowing image analysis on a per-arm-segment basis. We also perform a least-squares fit of a logarithmic spiral arc to the pixels in that segment, giving per-arc parameters, such as the pitch angle, arm segment length, location, etc. The algorithm takes about one minute per galaxies, and can easily be scaled using parallelism. We have run it on all ~644,000 Sloan objects that are larger than 40 pixels across and classified as "galaxies." We find a very good correlation between our quantitative description of a spiral structure and the qualitative description provided by Galaxy Zoo humans. Our objective, quantitative measures of structure demonstrate the difficulty in defining exactly what constitutes a spiral "arm," leading us to prefer the term "arm segment." We find that pitch angle often varies significantly segment-to-segment in a single spiral galaxy, making it difficult to define the pitch angle for a single galaxy. We demonstrate how our new database of arm segments can be queried to find galaxies satisfying specific quantitative visual criteria. For example, even though our code does not explicitly find rings, a good surrogate is to look for galaxies having one long, low-pitch-angle arm—which is how our code views ring galaxies. SpArcFiRe is available at http://sparcfire.ics.uci.edu.

  15. NMR methods for the investigation of structure and transport

    Energy Technology Data Exchange (ETDEWEB)

    Hardy, Edme H. [Karlsruher Institut fuer Technologie (KIT), Karlsruhe (Germany). Inst. fuer Mechanische Verfahrenstechnik und Mechanik

    2012-07-01

    Extensive derivations of required fundamental relations for readers with engineering background New applications based on MRI, PGSE-NMR, and low-field NMR New concepts in quantitative data evaluation and image analysis Methods of nuclear magnetic resonance (NMR) are increasingly applied in engineering sciences. The book summarizes research in the field of chemical and process engineering performed at the Karlsruhe Institute of Technology (KIT). Fundamentals of the methods are exposed for readers with an engineering background. Applications cover the fields of mechanical process engineering (filtration, solid-liquid separation, powder mixing, rheometry), chemical process engineering (trickle-bed reactor, ceramic sponges), bioprocess engineering (biofilm growth), and food process engineering (microwave heating, emulsions). Magnetic Resonance Imaging (MRI) as well as low-field NMR are covered with notes on hardware. Emphasis is placed on quantitative data analysis and image processing. (orig.)

  16. The effect of pitch in multislice spiral/helical CT; L'effet du pas dans la tomodensitometrie spiralee/helicoidale multidetecteurs

    Energy Technology Data Exchange (ETDEWEB)

    Wang, G.; Vannier, M.W. [Iowa Univ., Dept. of Radiology, Iowa City, IA (United States)

    2000-07-01

    The purpose of this study is to understand the effect of pitch on raw data interpolation in multislice spiral/helical computed tomography (CT) and provide guidelines for scanner design and protocol optimization. Multislice spiral CT is mainly characterized by the three parameters: the number of detector arrays, the detector collimation, and the table increment per x-ray source rotation. The pitch in multislice spiral CT is defined as the ratio of the table increment over the detector collimation in this study. In parallel to the current framework for studying longitudinal image resolution, the central fan-beam rays of direct and opposite directions are considered, assuming a narrow cone-beam angle. Generally speaking, sampling in the Radon domain by the direct and opposite central rays is nonuniform along the longitudinal axis. Using a recently developed methodology for quantifying the sensibility of signal reconstruction from non-uniformly sampled finite points, the effect of pitch on raw data interpolation is analyzed in multislice spiral CT. Unlike single-slice spiral CT, in which image quality decreases monotonically as the pitch increases, the sensibility of raw data interpolation in multislice spiral CT increases, suggesting that image quality does not decrease monotonically in this case. The most favorable pitch can be found from the sensitivity-slice spiral CT is provided. The study on the effect of pitch using the sensitivity analysis approach reveals the fundamental characteristics of raw data interpolation in multislice spiral CT, and gives insights into interaction between pitch and image quality. These results may be valuable for design of multislice spiral CT scanners and imaging protocol optimization in clinical applications. (authors)

  17. Mathematical Modeling of Spiral Heat Exchanger

    Directory of Open Access Journals (Sweden)

    Probal Guha , Vaishnavi Unde

    2014-04-01

    Full Text Available Compact Heat Exchangers (CHEs are increasingly being used on small and medium scale industries. Due to their compact size and efficient design, they facilitate more efficient heat transfer. Better heat transfer would imply lesser fuel consumption for the operations of the plant, giving improvement to overall efficiency. This reduction in consumption of fuel is a step towards sustainable development. This report exclusively deals with the study the spiral heat exchanger.The design considerations for spiral heat exchanger is that the flow within the spiral has been assumed as flow through a duct and by using Shah London empirical equation for Nusselt number design parameters are further optimized.This is accompanied by a detailed energy balance to generate a concise mathematical model

  18. Discontinuous spirals of stable periodic oscillations.

    Science.gov (United States)

    Sack, Achim; Freire, Joana G; Lindberg, Erik; Pöschel, Thorsten; Gallas, Jason A C

    2013-11-27

    We report the experimental discovery of a remarkable organization of the set of self-generated periodic oscillations in the parameter space of a nonlinear electronic circuit. When control parameters are suitably tuned, the wave pattern complexity of the periodic oscillations is found to increase orderly without bound. Such complex patterns emerge forming self-similar discontinuous phases that combine in an artful way to produce large discontinuous spirals of stability. This unanticipated discrete accumulation of stability phases was detected experimentally and numerically in a Duffing-like proxy specially designed to bypass noisy spectra conspicuously present in driven oscillators. Discontinuous spirals organize the dynamics over extended parameter intervals around a focal point. They are useful to optimize locking into desired oscillatory modes and to control complex systems. The organization of oscillations into discontinuous spirals is expected to be generic for a class of nonlinear oscillators.

  19. Discontinuous Spirals of Stable Periodic Oscillations

    Science.gov (United States)

    Sack, Achim; Freire, Joana G.; Lindberg, Erik; Pöschel, Thorsten; Gallas, Jason A. C.

    2013-01-01

    We report the experimental discovery of a remarkable organization of the set of self-generated periodic oscillations in the parameter space of a nonlinear electronic circuit. When control parameters are suitably tuned, the wave pattern complexity of the periodic oscillations is found to increase orderly without bound. Such complex patterns emerge forming self-similar discontinuous phases that combine in an artful way to produce large discontinuous spirals of stability. This unanticipated discrete accumulation of stability phases was detected experimentally and numerically in a Duffing-like proxy specially designed to bypass noisy spectra conspicuously present in driven oscillators. Discontinuous spirals organize the dynamics over extended parameter intervals around a focal point. They are useful to optimize locking into desired oscillatory modes and to control complex systems. The organization of oscillations into discontinuous spirals is expected to be generic for a class of nonlinear oscillators. PMID:24284508

  20. Cloud and Star Formation in Spiral Arms

    CERN Document Server

    Dobbs, Clare

    2014-01-01

    We present the results from simulations of GMC formation in spiral galaxies. First we discuss cloud formation by cloud-cloud collisions, and gravitational instabilities, arguing that the former is prevalent at lower galactic surface densities and the latter at higher. Cloud masses are also limited by stellar feedback, which can be effective before clouds reach their maximum mass. We show other properties of clouds in simulations with different levels of feedback. With a moderate level of feedback, properties such as cloud rotations and virial parameters agree with observations. Without feedback, an unrealistic population of overly bound clouds develops. Spiral arms are not found to trigger star formation, they merely gather gas into more massive GMCs. We discuss in more detail interactions of clouds in the ISM, and argue that these are more complex than early ideas of cloud-cloud collisions. Finally we show ongoing work to determine whether the Milky Way is a flocculent or grand design spiral.

  1. How Different are Normal and Barred Spirals?

    CERN Document Server

    Bergh, Sidney van den

    2011-01-01

    No significant color differences are found between normal and barred spirals over the range of Hubble stages a - ab - b - bc. Furthermore, no significant difference is seen between the luminosity distributions of normal and barred galaxies over the same range of Hubble stages. However, SBc galaxies are found to be systematically fainter than Sc galaxies at 99% confidence. The observation that normal and barred spirals with Hubble stages a - ab - b - bc have indistinguishable intrinsic colors hints at the possibility that the bars in such spiral galaxies might be ephemeral structures. Finally, it is pointed out that lenticular galaxies of types S0 and SB0 are systematically fainter than are other early-type galaxies, suggesting that such galaxies are situated on evolutionary tracks that differ systematically from those of galaxies that lie along the E - Sa - Sb -Sc and E - SBa - SBb - SBc sequences.

  2. The finite element modeling of spiral ropes

    Institute of Scientific and Technical Information of China (English)

    Juan Wu

    2014-01-01

    Accurate understanding the behavior of spiral rope is complicated due to their complex geometry and complex contact conditions between the wires. This study proposed the finite element models of spiral ropes subjected to tensile loads. The parametric equations developed in this paper were implemented for geometric modeling of ropes. The 3D geometric models with different twisting manner, equal diameters of wires were generated in details by using Pro/ENGINEER software. The results of the present finite element analysis were on an acceptable level of accuracy as compared with those of theoretical and experimental data. Further development is ongoing to analysis the equivalent stresses induced by twisting manner of cables. The twisting manner of wires was important to spiral ropes in the three wire layers and the outer twisting manner of wires should be contrary to that of the second layer, no matter what is the first twisting manner of wires.

  3. Inwardly rotating spirals in nonuniform excitable media.

    Science.gov (United States)

    Gao, Xiang; Feng, Xia; Cai, Mei-chun; Li, Bing-wei; Ying, He-ping; Zhang, Hong

    2012-01-01

    Inwardly rotating spirals (IRSs) have attracted great attention since their observation in an oscillatory reaction-diffusion system. However, IRSs have not yet been reported in planar excitable media. In the present work we investigate rotating waves in a nonuniform excitable medium, consisting of an inner disk part surrounded by an outer ring part with different excitabilities, by numerical simulations of a simple FitzHugh-Nagumo model. Depending on the excitability of the medium as well as the inhomogeneity, we find the occurrence of IRSs, of which the excitation propagates inwardly to the geometrical spiral tip.

  4. TRIGGERED STAR FORMATION IN SPIRAL ARMS

    Directory of Open Access Journals (Sweden)

    E. E. Martínez-García

    2009-01-01

    Full Text Available We present the status of our research, relative to the triggering of star formation by large-scale galactic shocks associated with spiral density waves. Around a third of the galaxies in our sample do not seem suitable for this kind of study, because they present an e ect, probably due to opacity, that is not well understood. The remaining objects seem to favor the idea of density wave triggering of star formation in the arms. The comparison with stellar population synthesis models, and the orbital resonance positions for these galaxies (derived by means of spiral pattern angular speeds corroborate this hypothesis.

  5. Beautiful math--aesthetic patterns based on logarithmic spirals.

    Science.gov (United States)

    Xinchang Wang; Peichang Ouyang

    2013-01-01

    A simple, fast method generates various visually appealing spiral patterns. The method is based on the concept that spiral patterns comprise a symmetry group of tilings. It employs invariant mappings and a dynamical system to create seamless colored patterns.

  6. Controlling spiral wave with target wave in oscillatory systems

    Institute of Scientific and Technical Information of China (English)

    Liu Fu-Cheng; Wang Xiao-Fei; Li Xue-Chen; Dong Li-Fang

    2007-01-01

    Spiral waves have been controlled by generating target waves with a localized inhomogeneity in the oscillatory medium. The competition between the spiral waves and target waves is discussed. The effect of the localized inhomogeneity size has also been studied.

  7. Comparison of radiation dose and image quality of Siremobil-IsoC{sup 3D} with a 16-slice spiral CT for diagnosis and intervention in the human pelvic bone; Vergleich von Strahlenexposition und Bildqualitaet eines Siremobil-IsoC{sup 3D} mit einem 16-Zeilen-Spiral-CT bei Diagnostik und Intervention am humanen Becken

    Energy Technology Data Exchange (ETDEWEB)

    Wieners, G.; Pech, M.; Beck, A.; Wust, P.; Felix, R.; Schroeder, R.J. [Klinik fuer Strahlenheilkunde, Charite, Univ. Berlin (Germany); Koenig, B.; Erdmenger, U.; Stoeckle, U. [Klinik fuer Unfallchirurgie, Charite, Univ. Berlin (Germany)

    2005-02-01

    Purpose: to compare the image quality of 16-slice computed tomography with the image quality of Siremobil-IsoC{sup 3D} of the pelvic region and to measure simultaneously the radiation dose before and after implantation of a sacroiliac screw (SI-screw) Materials and methods: the pelvic region of 8 human cadavers was examined in the Siremobil-IsoC{sup 3D} at five different levels. We used a standard protocol for the 16-slice CT of the complete pelvic region before and after insertion of a pelvic screw, followed by stepwise reduction of the tube current to find the tube current that equalizes the image quality of both modalities. We controlled the image quality by judging important structures such as neuroforamen, nerves, sacroiliacal joint space, intervertebral space, osteophytes, iliopsoas muscle, acetabular surface, fovea centralis, hip joint and os pubis. The image quality was judged by three radiologists and three trauma surgeons using a ranking from 1 to 5. The dose was measured with an endorectally placed NOMEX Dosimeter, to obtain the gonadal dose. Results: the medium score for all viewers of the Siremobil-IsoC{sup 3D} examinations was between 3 and 4.3. The medium score for all CT-examinations with a tube current of 250 mA was between 1.3 and 2.2. The reduction of tube current down to 80 mA hardly influenced the marks for the analyzed structures. Under 80 mA, bony structures, even after implantation of a SI-screw, were still marked as good, but soft tissue differentiation was getting worse. For the examination of the pelvis, the average dose-length product for the IsoC{sup 3D} was 41.2 mGy x cm. The medium dose-length product for CT was 389 mGy x cm for 250 mA, 125 mGy x cm for 80 mA and 82 mGy x cm for 60 mA. (orig.)

  8. A new method to estimate local pitch angles in spiral galaxies: Application to spiral arms and feathers in M81 and M51

    CERN Document Server

    Puerari, Ivânio; Block, David L

    2014-01-01

    We examine $8\\mu$m IRAC images of the grand design two-arm spiral galaxies M81 and M51 using a new method whereby pitch angles are locally determined as a function of scale and position, in contrast to traditional Fourier transform spectral analyses which fit to average pitch angles for whole galaxies. The new analysis is based on a correlation between pieces of a galaxy in circular windows of $(\\ln R, \\theta)$ space and logarithmic spirals with various pitch angles. The diameter of the windows is varied to study different scales. The result is a best-fit pitch angle to the spiral structure as a function of position and scale, or a distribution function of pitch angles as a function of scale for a given galactic region or area. We apply the method to determine the distribution of pitch angles in the arm and interarm regions of these two galaxies. In the arms, the method reproduces the known pitch angles for the main spirals on a large scale, but also shows higher pitch angles on smaller scales resulting from ...

  9. Strong Evidence for the Density-wave Theory of Spiral Structure in Disk Galaxies

    CERN Document Server

    Pour-Imani, Hamed; Kennefick, Julia; Davis, Benjamin L; Shields, Douglas W; Abdeen, Mohamed Shameer

    2016-01-01

    The density-wave theory of galactic spiral-arm structure makes a striking prediction that the pitch angle of spiral arms should vary with the wavelength of the galaxy's image. The reason is that stars are born in the density wave but move out of it as they age. They move ahead of the density wave inside the co-rotation radius, and fall behind outside of it, resulting in a tighter pitch angle at wavelengths that image stars (optical and near-infrared) than those that are associated with star formation (far-infrared and ultraviolet). In this study we combined large sample size with wide range of wavelengths, from the ultraviolet to the infrared to investigate this issue. For each galaxy we used an optical wavelength image (B-band: 445 nm) and images from the Spitzer Space Telescope at two infrared wavelengths (infrared: 3.6 and 8.0 {\\mu}m) and we measured the pitch angle with the 2DFFT and Spirality codes. We find that the B-band and 3.6 {\\mu}m images have smaller pitch angles than the infrared 8.0 {\\mu}m image...

  10. 肺挫伤患者多层螺旋CT影像学表现与预后%Association of multi-slice spiral CT images of occult pulmonary contusion with disease prognosis

    Institute of Scientific and Technical Information of China (English)

    王凌; 唐怨; 孔德会; 陈友强; 付子文; 杨华

    2014-01-01

    探讨肺挫伤(occult pulmonary contusion,OPC)患者多层螺旋CT(multi-slice spiral CT,MSCT)影像学表现与预后.对143例胸部钝性伤后行常规胸部正位平片和MSCT检查患者影像及临床资料进行回顾性分析.共87例患者检出肺挫伤,其中显性挫伤58例,24例继发肺炎,13例继发脓胸,16例继续发展为急性呼吸窘迫综合征(ARDS);隐匿性肺挫伤(OPC)29例,6例继发肺炎,1例发展为ARDS,未见继发脓胸患者;其余56例中7例继发肺炎,1例继发ARDS,未见继发脓胸患者.在OPC患者中,所有挫伤局限于一个肺叶的患者临床预后均较好;所有继发肺炎的患者挫伤范围均大于两个肺叶.OPC患者总体临床预后较好,MSCT能可靠的评价挫伤的范围,对OPC患者的临床治疗具有一定的指导意义.

  11. Evolution of Spiral Waves under Modulated Electric Fields

    Institute of Scientific and Technical Information of China (English)

    MA Jun; YING He-Ping; PAN Guo-Wei; PU Zhong-Sheng

    2005-01-01

    @@ Spirals generated from the excitable media within the Barkley model is investigated under the gradient electric fields by a numerical simulation. The spiral drift and spiral break up are observed when the amplitude of the electric fields is modulated by a constant signal or a chaotic signal. It is also verified that, even in the presence of the white noise, the whole system can reach homogeneous states after the spiral breakup, by using an adaptive strategy.

  12. A Non-invasive Method of Tracing Spiral Tips

    Institute of Scientific and Technical Information of China (English)

    王凯; 毛晓明; 欧阳颀

    2001-01-01

    A new method is developed to trace the tip of spiral waves in an excitable medium. The information of a spiraltip movement is obtained from only six probes. This method can trace the tip of a simple rotating spiral as wellas a complex spiral tip movement. More importantly, it can be used to distinguish between a spiral and a targetwave. The method is checked with data by experiments and numerical simulations, and found to be successful.

  13. Spiral Waves in Media with Spatial Period-2 Structure

    Institute of Scientific and Technical Information of China (English)

    YANG Jun-Zhong; ZHANG Mei

    2005-01-01

    @@ The spiral waves in a system of two-dimensional coupled oscillators with spatial period-2 structure are investigated.We find a sandwiched spiral wave where any adjacent oscillators are in anti-phase. We show that the propagation rate of the sandwiched spiral wave is insensitive to the change of the coupling constant. The influences of the local kinetics on the sandwiched spiral wave are also investigated.

  14. Cutoff-Free Traveling Wave NMR

    CERN Document Server

    Tang, Joel A; Sodickson, Daniel K; Jerschow, Alexej

    2011-01-01

    Recently, the concept of traveling-wave NMR/MRI was introduced by Brunner et al. (Nature 457, 994-992 (2009)), who demonstrated MR images acquired using radio frequency (RF) waves propagating down the bore of an MR scanner. One of the significant limitations of this approach is that each bore has a specific cutoff frequency, which can be higher than most Larmor frequencies of at the magnetic field strengths commonly in use for MR imaging and spectroscopy today. We overcome this limitation by using a central conductor in the waveguide and thereby converting it to a transmission line (TL), which has no cutoff frequency. Broadband propagation of waves through the sample thus becomes possible. NMR spectra and images with such an arrangement are presented and genuine traveling wave behavior is demonstrated. In addition to facilitating NMR spectroscopy and imaging in smaller bores via traveling waves, this approach also allows one to perform multinuclear traveling wave experiments (an example of which is shown), an...

  15. 某企业工业X射线实时成像检测系统螺旋钢管探伤放射防护现状%Radiological protection of a X-ray real-time imaging inspection system for industrial spiral steel pipe flaw detection

    Institute of Scientific and Technical Information of China (English)

    刘先平; 周龙成; 郭鲁琼

    2013-01-01

    [Objective]To understand the radiological protection status of X-ray real-time imaging inspection system for industrial spiral steel pipe flaw detection, and assess the effect on health of workers and the public during operation. [Methods] Through field survey of X-ray real-time imaging inspection system for industrial spiral steel-pipe flaw detection and the 2 X-ray detection rooms, FJ-347 A x-r dosimeter was used for Protection detection and safety evaluation in accordance with the relevant national radiological protection standards and methods. [ Results] The results showed dose rate of control rooms, room doors and external wall was close to the level of background radiation in 2 X-ray detection rooms, the workplace gates radiation leakage dose rate was 0. 50-1. 20 μGy/h (lower than the national standard limit 2. S μGy/h). Personal dose monitoring results of radiation workers in recent 2 years were lower than the national standard limit 1/10. [ Conclusion] During the operation of X-ray real-time imaging inspection system for industrial spiral steel pipe flaw detection in this enterprise, related radiation workers and the surrounding public are safe.%目的 了解工业X射线实时成像检测系统螺旋钢管探伤的放射防护状况,评估对放射工作人员和公众健康的影响.方法 对该企业2条X射线实时成像检测系统及2座探伤室的基本情况进行调查,使用FJ-347A X γ剂量仪,按照国家相关的放射卫生防护标准与方法对探伤现场进行防护检测和安全性评价.结果 2座探伤室的操作位、探伤室小防护门、探伤室墙体外剂量率接近辐射本底水平,车间大防护门表面剂量率0.50~ 1.20μGy/h(低于国家标准限值2.5 μGy/h,);近2年放射工作人员个人剂量监测结果均低于国家标准年限制的1/10.结论 该企业工业螺旋钢管X射线实时成像检测系统运行时,相关放射工作人员和周围公众是安全的.

  16. The acquisition of multidimensional NMR spectra within a single scan

    Science.gov (United States)

    Frydman, Lucio; Scherf, Tali; Lupulescu, Adonis

    2002-01-01

    A scheme enabling the complete sampling of multidimensional NMR domains within a single continuous acquisition is introduced and exemplified. Provided that an analyte's signal is sufficiently strong, the acquisition time of multidimensional NMR experiments can thus be shortened by orders of magnitude. This could enable the characterization of transient events such as proteins folding, 2D NMR experiments on samples being chromatographed, bring the duration of higher dimensional experiments (e.g., 4D NMR) into the lifetime of most proteins under physiological conditions, and facilitate the incorporation of spectroscopic 2D sequences into in vivo imaging investigations. The protocol is compatible with existing multidimensional pulse sequences and can be implemented by using conventional hardware; its performance is exemplified here with a variety of homonuclear 2D NMR acquisitions. PMID:12461169

  17. NMR, Water and Plants

    NARCIS (Netherlands)

    As, van H.

    1982-01-01

    This Thesis describes the application of a non-destructive pulsed proton NMR method mainly to measure water transport in the xylem vessels of plant stems and in some model systems. The results are equally well applicable to liquid flow in other biological objects than plants, e.g. flow of blood and

  18. Autonomous driving in NMR.

    Science.gov (United States)

    Perez, Manuel

    2017-01-01

    The automatic analysis of NMR data has been a much-desired endeavour for the last six decades, as it is the case with any other analytical technique. This need for automation has only grown as advances in hardware; pulse sequences and automation have opened new research areas to NMR and increased the throughput of data. Full automatic analysis is a worthy, albeit hard, challenge, but in a world of artificial intelligence, instant communication and big data, it seems that this particular fight is happening with only one technique at a time (let this be NMR, MS, IR, UV or any other), when the reality of most laboratories is that there are several types of analytical instrumentation present. Data aggregation, verification and elucidation by using complementary techniques (e.g. MS and NMR) is a desirable outcome to pursue, although a time-consuming one if performed manually; hence, the use of automation to perform the heavy lifting for users is required to make the approach attractive for scientists. Many of the decisions and workflows that could be implemented under automation will depend on the two-way communication with databases that understand analytical data, because it is desirable not only to query these databases but also to grow them in as much of an automatic manner as possible. How these databases are designed, set up and the data inside classified will determine what workflows can be implemented. Copyright © 2016 John Wiley & Sons, Ltd.

  19. Evaluation of image quality and dose in thoracic spiral CT examination in patients with pulmonary carcinoma. Preliminary results; Evaluacion de la calidad de imagen y de la dosis en examenes de TC helicoidal de torax en pacientes con carcinoma de pulmon. Resultados preliminares

    Energy Technology Data Exchange (ETDEWEB)

    Moran-Blanco, L. M.; Rodriguez-Gonzalez, R.; Calzado-Cantera, A.; Arenas de Pablo, A.; Baeza-Trujillo, M.; Cuevas-Ibanez, A.; Garcia-Castano, B.; Gomez-Leon, N.; Turrero-Nogues, A.; Moran-Penco, P.

    2002-07-01

    We have applied criteria for CT quality defined in the European Guidelines to a samples of thoracic CT examinations for the indication of pulmonary carcinoma of 5 institutions of the Community of Madrid that have spiral CT equipment. The selected examinations have been evaluated independently by five radiologists to determine the degree of adherence to the quality criteria for image defined in the Guidelines s for examinations of general thorax. Dosimetric measurements carried out in parallel have served to estimate the values of CT (CTDI{sub w}) dose indices, dose-length product (DLP) and effective dose for every patient. The result show a high global adherence to the quality criteria (96%), with averages per institution being between 94% (in two institutions) and 98% (in three institutions). There are 10 of 16 criteria that are adhered to in all examinations of the sample: those which are not adhered to systematically are: two of visualization (1.1 and 1.4), with 92-96% fulfillment, and four of critical reproduction (2.6; 2.8; 2.9 and 2.10), with percentages of adherence between 91% and 96%. The average CTDI{sub w} values per institution are in the interval 12.9-19.1 mGy; those of DLP between 263 and 577 mGy cm and those of effective dose between 4.2 and 9.2 mSv. The DLP-image quality correlation in institutions with the best image quality was null in two of them and direct and moderate in the third. In both institutions with the poorest image: (Author) 20 refs.

  20. NMR Hyperpolarization Techniques of Gases.

    Science.gov (United States)

    Barskiy, Danila A; Coffey, Aaron M; Nikolaou, Panayiotis; Mikhaylov, Dmitry M; Goodson, Boyd M; Branca, Rosa T; Lu, George J; Shapiro, Mikhail G; Telkki, Ville-Veikko; Zhivonitko, Vladimir V; Koptyug, Igor V; Salnikov, Oleg G; Kovtunov, Kirill V; Bukhtiyarov, Valerii I; Rosen, Matthew S; Barlow, Michael J; Safavi, Shahideh; Hall, Ian P; Schröder, Leif; Chekmenev, Eduard Y

    2017-01-18

    Nuclear spin polarization can be significantly increased through the process of hyperpolarization, leading to an increase in the sensitivity of nuclear magnetic resonance (NMR) experiments by 4-8 orders of magnitude. Hyperpolarized gases, unlike liquids and solids, can often be readily separated and purified from the compounds used to mediate the hyperpolarization processes. These pure hyperpolarized gases enabled many novel MRI applications including the visualization of void spaces, imaging of lung function, and remote detection. Additionally, hyperpolarized gases can be dissolved in liquids and can be used as sensitive molecular probes and reporters. This Minireview covers the fundamentals of the preparation of hyperpolarized gases and focuses on selected applications of interest to biomedicine and materials science. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. 320排螺旋 CT 灌注成像对小肝癌患者诊断价值的初步研究%Diagnostic Value of 320-Slice Spiral CT Perfusion Imaging in Patients with Small Hepatocellular Carcinoma

    Institute of Scientific and Technical Information of China (English)

    柳勇; 陈万洪; 马军; 董浩; 钟井松

    2014-01-01

    目的:研究320排螺旋 CT 灌注成像对小肝癌患者的诊断价值。方法对10例经手术或活检证实的小肝癌患者的 CT 表现进行回顾性分析。应用最大斜率法计算小肝癌及肿瘤以外正常肝脏组织的肝动脉血流灌注量(HAF)、门静脉血流灌注量(HPF)及灌注指数(PI),并采用色阶赋值形成灌注影像,获取感兴趣区参数图。结果小肝癌的HAF、PI 明显高于同一患者肝肿瘤以外的正常肝脏组织,HPF 明显低于同一患者肝肿瘤以外的正常肝脏组织(均 P <0.05)。结论320排 CT 灌注成像扫描范围可以覆盖整个全肝,有效地显示小肝癌灌注参数值,对难以诊断的小肝癌提供了早期诊断的依据。%Objective To investigate the diagnostic value of 320-slice spiral CT perfusion ima-ging in patients with small hepatocellular carcinoma.Methods CT findings were analyzed retro-spectively in 10 patients with small hepatocellular carcinoma confirmed by surgery or biopsy.The maximum slope method was used to calculate the hepatic arterial flow (HAF),hepatic portal flow (HPF)and perfusion index (PI)in small hepatocellular carcinoma and normal liver tissue.Furthermore, color maps for each perfusion parameter were displayed.Results Compared with normal liver tissue,the HAF and PI increased but HPF decreased in small hepatocellular carcinoma (P<0.05).Conclusion The 320-slice spiral CT whole-liver perfusion imaging can effectively display the perfusion parameters and provide a basis for early diagnosis of small hepatocellular carcinoma.

  2. NMR for chemists and biologists

    CERN Document Server

    Carbajo, Rodrigo J

    2013-01-01

    This book offers a concise introduction to the field of nuclear magnetic resonance or NMR. It presents the basic foundations of NMR in a non-mathematical way and provides an overview of both recent and important biological applications of NMR.

  3. NMR magnet technology at MIT

    Energy Technology Data Exchange (ETDEWEB)

    Williams, J.E.C.; Bobrov, E.S.; Iwasa, Y.; Punchard, W.F.B.; Wrenn, J.; Zhukovsky, A. (Massachusetts Inst. of Tech., Cambridge, MA (United States). Francis Bitter National Magnet Lab.)

    1992-01-01

    The design and construction of high field superconducting NMR magnets has much in common with other types of adiabatic superconducting magnets. However, two issues have a particular relevance to NMR magnets. They are field drift and homogeneity. In this paper the control of these factors in the particular context of high field NMR spectrometer magnets is examined.

  4. Spiral Arms in the Asymmetrically Illuminated Disk of MWC 758 and Constraints on Giant Planets

    CERN Document Server

    Grady, C A; Hashimoto, J; Fukagawa, M; Currie, T; Biller, B; Thalmann, C; Sitko, M L; Russell, R; Wisniewski, J; Dong, R; Kwon, J; Sai, S; Hornbeck, J; Schneider, G; Hines, D; Moro-Martin, A; Feldt, M; Henning, Th; Pott, J -U; Bonnefoy, M; Bouwman, J; Lacour, S; Mueller, A; Juhasz, A; Crida, A; Chauvin, G; Andrews, S; Wilner, D; Kraus, A; Dahm, S; Robitaille, T; Jang-Condell, H; Abe, L; Akiyama, E; Brandner, W; Brandt, T; Carson, J; Egner, S; Follette, K B; Goto, M; Guyon, O; Hayano, Y; Hayashi, M; Hayashi, S; Hodapp, K; Ishii, M; Iye, M; Janson, M; Kandori, R; Knapp, G; Kudo, T; Kusakabe, N; Kuzuhara, M; Mayama, S; McElwain, M; Matsuo, T; Miyama, S; Morino, J -I; Nishimura, T; Pyo, T -S; Serabyn, G; Suto, H; Suzuki, R; Takami, M; Takato, N; Terada, H; Tomono, D; Turner, E; Watanabe, M; Yamada, T; Takami, H; Usuda, T; Tamura, M

    2012-01-01

    We present the first near-IR scattered light detection of the transitional disk associated with the Herbig Ae star MWC 758 using data obtained as part of the Strategic Exploration of Exoplanets and Disks with Subaru, and 1.1 micron HST/NICMOS data. While sub-millimeter studies suggested there is a dust-depleted cavity with r=0.35, we find scattered light as close as 0.1 (20-28 AU) from the star, with no visible cavity at H, K', or Ks. We find two small-scaled spiral structures which asymmetrically shadow the outer disk. We model one of the spirals using spiral density wave theory, and derive a disk aspect ratio of h ~ 0.18, indicating a dynamically warm disk. If the spiral pattern is excited by a perturber, we estimate its mass to be 5+3,-4 Mj, in the range where planet filtration models predict accretion continuing onto the star. Using a combination of non-redundant aperture masking data at L' and angular differential imaging with Locally Optimized Combination of Images at K' and Ks, we exclude stellar or ma...

  5. Turbulence and Star Formation in a Sample of Spiral Galaxies

    CERN Document Server

    Maier, Erin; Hunter, Deidre A

    2016-01-01

    We investigate turbulent gas motions in spiral galaxies and their importance to star formation in far outer disks, where the column density is typically far below the critical value for spontaneous gravitational collapse. Following the methods of Burkhart et al. (2010) on the Small Magellanic Cloud, we use the third and fourth statistical moments, as indicators of structures caused by turbulence, to examine the neutral hydrogen (HI) column density of a sample of spiral galaxies selected from The HI Nearby Galaxy Survey (THINGS, Walter et al. 2008). We apply the statistical moments in three different methods- the galaxy as a whole, divided into a function of radii and then into grids. We create individual grid maps of kurtosis for each galaxy. To investigate the relation between these moments and star formation, we compare these maps with their far-ultraviolet images taken by the Galaxy Evolution Explorer (GALEX) satellite. We find that the moments are largely uniform across the galaxies, in which the variatio...

  6. Short WSRT HI observations of spiral galaxies

    NARCIS (Netherlands)

    Rhee, MH; vanAlbada, TS

    1996-01-01

    We have obtained short HI observations of 60 late type spiral galaxies with the Westerbork Synthesis Radio Telescope (WSRT). Several HI properties are presented, including the radial surface density distribution of HI and a position-velocity map. When possible these are compared to those measured fr

  7. Spiral kicker for the beam abort system

    Energy Technology Data Exchange (ETDEWEB)

    Martin, R.L.

    1983-01-01

    A brief study was carried out to determine the feasibility of a special kicker to produce a damped spiral beam at the beam dump for the beam abort system. There appears to be no problem with realizing this concept at a reasonably low cost.

  8. How to make a spiral bacterium

    Science.gov (United States)

    Wolgemuth, Charles W.; Inclan, Yuki F.; Quan, Julie; Mukherjee, Sulav; Oster, George; Koehl, M. A. R.

    2005-09-01

    The motility of some kinds of bacteria depends on their spiral form, as does the virulence of certain pathogenic species. We propose a novel mechanism for the development of spiral shape in bacteria and the supercoiling of chains ('filaments') of many cells. Recently discovered actin-like proteins lying just under the cell wall form fibers that play a role in maintaining cell shape. Some species have a single actin-like fiber helically wrapped around the cell, while others have two fibers wrapped in the same direction. Here, we show that if these fibers elongate more slowly than growth lengthens the cell, the cell both twists and bends, taking on a spiral shape. We tested this mechanism using a mathematical model of expanding fiber-wound structures and via experiments that measure the shape changes of elongating physical models. Comparison of the model with in vivo experiments on stationary phase Caulobacter crescentus filaments provide the first evidence that mechanical stretching of cytoskeletal fibers influences cell morphology. Any hydraulic cylinder can spiral by this mechanism if it is reinforced by stretch-resistant fibers wrapped helically in the same direction, or shortened by contractile elements. This might be useful in the design of man-made actuators.

  9. Some optical properties of the spiral inflector

    CERN Document Server

    Toprek, D

    1999-01-01

    This paper compares some optical properties of different spiral inflectors using the program CASINO. The electric field distribution in the inflectors has been numerically calculated from an electric potential map produced by the program RELAX3D. The magnetic field is assumed to be constant. We have also made an effort to minimize the inflector fringe field using the RELAX3D program. (author)

  10. Maximum life spiral bevel reduction design

    Science.gov (United States)

    Savage, M.; Prasanna, M. G.; Coe, H. H.

    1992-07-01

    Optimization is applied to the design of a spiral bevel gear reduction for maximum life at a given size. A modified feasible directions search algorithm permits a wide variety of inequality constraints and exact design requirements to be met with low sensitivity to initial values. Gear tooth bending strength and minimum contact ratio under load are included in the active constraints. The optimal design of the spiral bevel gear reduction includes the selection of bearing and shaft proportions in addition to gear mesh parameters. System life is maximized subject to a fixed back-cone distance of the spiral bevel gear set for a specified speed ratio, shaft angle, input torque, and power. Significant parameters in the design are: the spiral angle, the pressure angle, the numbers of teeth on the pinion and gear, and the location and size of the four support bearings. Interpolated polynomials expand the discrete bearing properties and proportions into continuous variables for gradient optimization. After finding the continuous optimum, a designer can analyze near optimal designs for comparison and selection. Design examples show the influence of the bearing lives on the gear parameters in the optimal configurations. For a fixed back-cone distance, optimal designs with larger shaft angles have larger service lives.

  11. The handedness of historiated spiral columns.

    Science.gov (United States)

    Couzin, Robert

    2016-11-17

    Trajan's Column in Rome (AD 113) was the model for a modest number of other spiral columns decorated with figural, narrative imagery from antiquity to the present day. Most of these wind upwards to the right, often with a congruent spiral staircase within. A brief introductory consideration of antique screw direction in mechanical devices and fluted columns suggests that the former may have been affected by the handedness of designers and the latter by a preference for symmetry. However, for the historiated columns that are the main focus of this article, the determining factor was likely script direction. The manner in which this operated is considered, as well as competing mechanisms that might explain exceptions. A related phenomenon is the reversal of the spiral in a non-trivial number of reproductions of the antique columns, from Roman coinage to Renaissance and baroque drawings and engravings. Finally, the consistent inattention in academic literature to the spiral direction of historiated columns and the repeated publication of erroneous earlier reproductions warrants further consideration.

  12. Investigation of Spiral and Sweeping Holes

    Science.gov (United States)

    Thurman, Douglas; Poinsatte, Philip; Ameri, Ali; Culley, Dennis; Raghu, Surya; Shyam, Vikram

    2015-01-01

    Surface infrared thermography, hotwire anemometry, and thermocouple surveys were performed on two new film cooling hole geometries: spiral/rifled holes and fluidic sweeping holes. The spiral holes attempt to induce large-scale vorticity to the film cooling jet as it exits the hole to prevent the formation of the kidney shaped vortices commonly associated with film cooling jets. The fluidic sweeping hole uses a passive in-hole geometry to induce jet sweeping at frequencies that scale with blowing ratios. The spiral hole performance is compared to that of round holes with and without compound angles. The fluidic hole is of the diffusion class of holes and is therefore compared to a 777 hole and Square holes. A patent-pending spiral hole design showed the highest potential of the non-diffusion type hole configurations. Velocity contours and flow temperature were acquired at discreet cross-sections of the downstream flow field. The passive fluidic sweeping hole shows the most uniform cooling distribution but suffers from low span-averaged effectiveness levels due to enhanced mixing. The data was taken at a Reynolds number of 11,000 based on hole diameter and freestream velocity. Infrared thermography was taken for blowing rations of 1.0, 1.5, 2.0, and 2.5 at a density ration of 1.05. The flow inside the fluidic sweeping hole was studied using 3D unsteady RANS.

  13. Colloidal spirals in nematic liquid crystals.

    Science.gov (United States)

    Senyuk, Bohdan; Pandey, Manoj B; Liu, Qingkun; Tasinkevych, Mykola; Smalyukh, Ivan I

    2015-12-07

    One of the central experimental efforts in nematic colloids research aims to explore how the interplay between the geometry of particles along with the accompanying nematic director deformations and defects around them can provide a means of guiding particle self-assembly and controlling the structure of particle-induced defects. In this work, we design, fabricate, and disperse low-symmetry colloidal particles with shapes of spirals, double spirals, and triple spirals in a nematic fluid. These spiral-shaped particles, which are controlled by varying their surface functionalization to provide tangential or perpendicular boundary conditions of the nematic molecular alignment, are found inducing director distortions and defect configurations with non-chiral or chiral symmetry. Colloidal particles also exhibit both stable and metastable multiple orientational states in the nematic host, with a large number of director configurations featuring both singular and solitonic nonsingular topological defects accompanying them, which can result in unusual forms of colloidal self-assembly. Our findings directly demonstrate how the symmetry of particle-generated director configurations can be further lowered, or not, as compared to the low point group symmetry of solid micro-inclusions, depending on the nature of induced defects while satisfying topological constraints. We show that achiral colloidal particles can cause chiral symmetry breaking of elastic distortions, which is driven by complex three-dimensional winding of induced topological line defects and solitons.

  14. Biofouling of spiral wound membrane systems

    NARCIS (Netherlands)

    Vrouwenvelder, J.S.

    2009-01-01

    Biofouling of spiral wound membrane systems High quality drinking water can be produced with membrane filtration processes like reverse osmosis (RO) and nanofiltration (NF). Because the global demand for fresh clean water is increasing, these membrane technologies will increase in importance in the

  15. The Spiral Curriculum. Research into Practice

    Science.gov (United States)

    Johnston, Howard

    2012-01-01

    The Spiral Curriculum is predicated on cognitive theory advanced by Jerome Bruner (1960), who wrote, "We begin with the hypothesis that any subject can be taught in some intellectually honest form to any child at any stage of development." In other words, even the most complex material, if properly structured and presented, can be understood by…

  16. Exploring the limits to spatially resolved NMR

    Energy Technology Data Exchange (ETDEWEB)

    Gaedke, Achim; Nestle, Nikolaus [TU Darmstadt, Institute of Condensed Matter Physics (Germany)

    2010-07-01

    Recent advances in MRI have demonstrated resolutions down to 1 {mu}m. Magnetic resonance force microscopy has the potential to reach sensitivity for single nuclear spins. Given these numbers, in vivo imaging of single cells or even biomacromolecules may seem possible. However, for in vivo applications, there are fundamental differences in the contrast mechanisms compared to MRI at macroscopic scales as the length scale of of molecular self-diffusion exceeds that of the spatial resolution on the NMR time scale. Those effects - which are fundamentally different from the echo attenuation in field gradient NMR - even may lead to general limitations on the spatial resolution achievable in aqueous systems with high water content. In our contribution, we explore those effects on a model system in a high-resolution stray-field imaging setup. In addition to experimental results, simulations based on the Bloch-Torrey equation are presented.

  17. AN M DWARF COMPANION AND ITS INDUCED SPIRAL ARMS IN THE HD 100453 PROTOPLANETARY DISK

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Ruobing [Nuclear Science Division, Lawrence Berkeley National Lab, Berkeley, CA 94720 (United States); Zhu, Zhaohuan [Princeton University, Princeton, NJ 08544 (United States); Fung, Jeffrey; Chiang, Eugene [Department of Astronomy, University of California at Berkeley, Berkeley, CA 94720 (United States); Rafikov, Roman [Institute for Advanced Study, Princeton, NJ 08540 (United States); Wagner, Kevin, E-mail: rdong2013@berkeley.edu [Department of Astronomy/Steward Observatory, The University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States)

    2016-01-01

    Recent VLT/SPHERE near-infrared imaging observations revealed two spiral arms with a near m = 2 rotational symmetry in the protoplanetary disk around the ∼1.7 M{sub ⊙} Herbig star HD 100453. A ∼0.3 M{sub ⊙} M dwarf companion, HD 100453 B, was also identified at a projected separation of 120 AU from the primary. In this Letter, we carry out hydrodynamic and radiative transfer simulations to examine the scattered light morphology of the HD 100453 disk as perturbed by the companion on a circular and coplanar orbit. We find that the companion truncates the disk at ∼45 AU in scattered light images, and excites two spiral arms in the remaining (circumprimary) disk with a near m = 2 rotational symmetry. Both the truncated disk size and the morphology of the spirals are in excellent agreement with the SPHERE observations at Y, J, H, and K1-bands, suggesting that the M dwarf companion is indeed responsible for the observed double-spiral-arm pattern. Our model suggests that the disk is close to face on (inclination angle ∼5°), and that the entire disk-companion system rotates counterclockwise on the sky. The HD 100453 observations, along with our modeling work, demonstrate that double spiral arm patterns in near-infrared scattered light images can be generically produced by companions, and support future observations to identify the companions responsible for the arms observed in the MWC 758 and SAO 206462 systems.

  18. Curved spiral antennas for underwater biological applications

    Science.gov (United States)

    Llamas, Ruben

    We developed curved spiral antennas for use in underwater (freshwater) communications. Specifically, these antennas will be integrated in so-called mussel backpacks. Backpacks are compact electronics that incorporate sensors and a small radio that operate around 300 MHz. Researchers attach these backpacks in their freshwater mussel related research. The antennas must be small, lightweight, and form-fit the mussel. Additionally, since the mussel orientation is unknown, the antennas must have broad radiation patterns. Further, the electromagnetic environment changes significantly as the mussels burrow into the river bottom. Broadband antennas, such a spiral antennas, will perform better in this instance. While spiral antennas are well established, there has been little work on their performance in freshwater. Additionally, there has been some work on curved spiral antennas, but this work focused on curving in one dimension, namely curving around a cylinder. In this thesis we develop spiral antennas that curve in two dimensions in order to conform the contour of a mussel's shell. Our research has three components, namely (a) an investigation of the relevant theoretical underpinning of spiral antennas, (b) extensive computer simulations using state-of-the art computational electromagnetics (CEM) simulation software, and (c) experimental validation. The experimental validation was performed in a large tank in a laboratory setting. We also validated some designs in a pool (~300,000 liters of water and ~410 squared-meter dive pool) with the aid of a certified diver. To use CEM software and perform successful antenna-related experiments require careful attention to many details. The mathematical description of radiation from an antenna, antenna input impedance and so on, is inherently complex. Engineers often make simplifying assumptions such as assuming no reflections, or an isotropic propagation environment, or operation in the antenna far field, and so on. This makes

  19. Development of a surface micromachined spiral-channel viscous pump

    Science.gov (United States)

    Kilani, Mohammad Ibrahim

    This work introduces a new pump, called the spiral pump, which targets the surface micromachining technology. We demonstrate the possibility of realizing the spiral pump geometry in standard surface micromachining, lay out the theoretical foundation for its operation, and conduct an objective assessment for its practicality. The spiral pump is a shear-driven viscous pump, which works by rotating a disk with a spiral groove at a close proximity over a stationary plate. Fluid contained in the spiral groove between the stationary plate and the rotating disk, is subject to a net tangential viscous stress, which allows it to be transported against an imposed pressure difference. A number of spiral pumps were fabricated in 5 levels of polysilicon using Sandia's Ultraplanar Multilevel Surface Micromachining Technology, SUMMiT, and the fabricated micropump were tested in dry-run mode using electrostatic probing and optical microscopy. To achieve a more comprehensive understanding of the spiral micropump operation, an analytical model was developed for the flow field in the spiral channel of the pump using an approximation which replaces the spiral channel with an equivalent straight channel with appropriate dimensions and boundary conditions. An analytical solution for this model at the lubrication limit relates the flow rate, torque and power consumption of the spiral pump to the pressure difference and rotation rate. The model was validated using macroscale experiments conducted on a scaled up spiral pump model, which involved a quantitative characterization of the spiral pump performance. Those experiments validate the developed theory and help assess the practicality of the spiral pump concept. In addition to the spiral pump, two positive-displacement ring-gear pumps were designed and fabricated in this work. The feasibility of surface micromachined ring-gear pumps is briefly investigated in this work, and compare to that of the spiral micropump.

  20. Information Systems - Cancer Imaging Program

    Science.gov (United States)

    The Lung Image Database Consortium (LIDC) represents an effort by CIP grantees in a consortium to create a database of spiral CT images of the lung for use in CAD (computer-aided detection) algorithm research. The Imaging Database Resources Initiative (IDRI) is extending the efforts of the LIDC, to create a larger database of spiral CT imaging of the lung for use in CAD algorithm research. Image Archive Resources contains links to Web sites related to the interests of the NCI CIP Image Archive Committee. The Molecular Imaging and Contrast Agent Database (MICAD) is a database of research data on in vivo molecular imaging and contrast agents.

  1. Value of 64-slice spiral CT perfusion imaging in estimating the efficacy of transcatheter arterial chemoembolization for the treatment of hepatocellular carcinoma%64排螺旋CT灌注成像在肝细胞癌介入治疗前后的评估价值

    Institute of Scientific and Technical Information of China (English)

    2014-01-01

    Objective To discuss the clinical value of 64-slice spiral CT perfusion imaging(CTPI) in estimating the efficacy of transcatheter arterial chemoembolization ( TACE ) for hepatocellular carcinoma (HCC).Methods Using 64-slice spiral CT(GE LightSpeed VCT XT),all CT plain scan and perfusion scan were performed in 30 patients with HCC 1-3 days before and 30-40 days after TACE .Using deconvolution through Infusion Software analysis , hepatic blood flow ( BF ) , blood volume ( BV ) , the mean transit time ( MTT) , hepatic arterial fraction ( HAF ) , permeability surface ( PS ) were caculated to evaluate HCC embolization hemodynamic status .Results After TACE,the tumor was totally filled with lipiodol in 12 cases and partially filled with lipiodol in 18 cases.BF,BV,MTT,HAF and PS perfusion maps showed that lack of blood perfusion was found in lipiodol-filling areas, but sparsely or insufficiently lipiodol-filled areas were hyperperfusion.BF,BV,HAF and PS of HCC after TACE were lower than those of HCC before TACE (P0.05 ) .Conclusions 64-slice spiral CT liver perfusion imaging can be used to monitor the blood supply changes in non -iodized oil deposits area non-invasively ,dynamically ,quantitatively ,which was very important in judging the tumor tissue survival and played an important role in response evaluation of HCC interventional therapy and guiding the follow -up treatment.%目的:探讨64排螺旋CT灌注成像(CTPI)在原发性肝细胞癌(HCC)肝动脉插管化疗栓塞( TACE )术前、后疗效的评估价值。方法选取30例HCC 患者,于TACE术前1~3 d、术后30~40 d应用GE LightSpeed VCT XT(64排128层螺旋CT)分别行全肝常规平扫及灌注扫描,运用灌注软件进行分析,计算肝血流量(BF)、血容量(BV)、平均通过时间(MTT)、肝动脉灌注指数(HAF)、毛细血管通透性( PS )等,统计分析相关参数,以评价 HCC 介入治疗前后的血流动力学状态。结果 TACE

  2. 多层螺旋CT灌注成像在肾脏良恶性肿瘤鉴别诊断中的临床应用%Clinical Application of Multi - slice Spiral CT Perfusion Imaging in the Differential Diagnosis of Benign and Malignant Renal Tumors

    Institute of Scientific and Technical Information of China (English)

    赵红; 夏文平; 李培

    2012-01-01

    Objective To discuss the clinical practice value of multi - slice spiral CT perfusion imaging in the differential diagnosis of benign and malignant renal tumors. Methods Using multi - slice spiral CT machine, we detected the CT perfusion parameters of 20 cases of normal healthy volunteers(the control group) ,22 cases of renal clear cell carcinoma proved by operation (the renal carcinoma group) and 18 cases of renal hamarloma( the renal hamartoma group). Perfusion (perfusion) , relative blood volume (rBV) , time to peak (TTP) and peak enhancementimage (PEI) were obtained and calaculated. Results ①The perfusion,PEI of the renal carcinoma group Were significantly lower than thnse of the coutrol group, while the rBV.TTP were significantly higher than those of the control group; ② The perfusion, PEI of the renal hamarlunia group were significantly lower than those of the control group, while the rBV ,TTP of the renal hamanoma group were significantly higher than those of the control group; ③The perfusion .PEI of ihe renal carcinoma group were significantly higher than those of the renal hamartoma group, while the rBV,TTP of the renal carcinoma group were significantly lower lhan those of renal hamartoma group. The differences were significant statistically significant. Conclusion Multi - slice spiral CT perfusinn imaging can quantitatively assess hemortynamics variation of the normal kidney,benign and malignant renal tumors. It can provide a reliable hasis for differential diagnosis,which has important clinical application value.%目的 探讨多层螺旋CT(MSCTPI)灌注成像在肾脏良恶性肿瘤鉴别诊断中的应用价值.方法 采用多层螺旋CT机对正常健康志愿者20例(对照组)及经手术病理证实的肾透明细胞癌患者22例(肾癌组)、肾错构瘤患者18例(肾错构瘤组)的肾皮质CT灌注参数进行检测,分别计算:灌注(perfusion);相对组织血容量(rBV);峰值时间(TTP);峰值增强影像(PEI).结果 ①肾

  3. Spiral CT for evaluation of chest trauma; Spiral-CT beim Thoraxtrauma

    Energy Technology Data Exchange (ETDEWEB)

    Roehnert, W. [Universitaetsklinikum Dresden (Germany). Inst. und Poliklinik fuer Radiologische Diagnostik; Weise, R. [Universitaetsklinikum Dresden (Germany). Inst. und Poliklinik fuer Radiologische Diagnostik

    1997-07-01

    After implementation of spiral CT in our department, we carried out an analysis for determining anew the value of CT as a modality of chest trauma diagnosis in the emergency department. The retrospective study covers a period of 10 months and all emergency patients with chest trauma exmined by spiral CT. The major lesions of varying seriousness covered by this study are: pneumothorax, hematothorax, pulmonary contusion or laceration, mediastinal hematoma, rupture of a vessel, injury of the heart and pericardium. The various fractures are not included in this study. In many cases, spiral CT within relatively short time yields significant diagnostic findings, frequently saving additional angiography. A rigid diagnostic procedure cannot be formulated. Plain-film chest radiography still remains a diagnostic modality of high value. (Orig.) [Deutsch] Nach Einfuehrung der Spiral-CT in unserer Einrichtung versuchten wir, den Stellenwert der Computertomographie in der Notfalldiagnostik des Thoraxtraumas neu zu bestimmen. Dazu wurden retrospektiv ueber einen Zeitraum von 10 Monaten alle mittels Spiral-CT untersuchten Notfallpatienten mit Thoraxverletzungen ausgewertet. Im Vordergrund standen folgende Befunde unterschiedlichen Schweregrades: Pneumothorax, Haematothorax, Lungenkontusion/-lazeration, Mediastinalhaematom, Gefaessruptur, Herz- und Herzbeutelverletzung. Auf die unterschiedlichen Frakturen wird bewusst nicht naeher eingegangen. In vielen Faellen liefert die Spiral-CT mit relativ geringem Zeitaufwand wesentliche diagnostische Aussagen. Haeufig kann auf eine Angiographie verzichtet werden. Ein starres diagnostisches Stufenschema laesst sich nicht definieren. Die Thoraxuebersichtsaufnahme besitzt einen unveraendert hohen Stellenwert. (orig.)

  4. The detection of spiral arm modulation in the stellar disk of an optically flocculent and an optically grand design galaxy

    CERN Document Server

    Puerari, I; Elmegreen, B G; Frogel, J A; Eskridge, P B; Puerari, Ivanio; Block, David L.; Elmegreen, Bruce G.; Frogel, Jay A.; Eskridge, Paul B.

    2000-01-01

    Two dimensional Fourier spectra of near-infrared images of galaxies provide a powerful diagnostic tool for the detection of spiral arm modulation in stellar disks. Spiral arm modulation may be understood in terms of interference patterns of outgoing and incoming density wave packets or modes. The brightness along a spiral arm will be increased where two wave crests meet and constructively interfere, but will be decreased where a wave crest and a wave trough destructively interfere. Spiral arm modulation has hitherto only been detected in grand design spirals (such as Messier 81). Spiral arm amplitude variations have the potential to become a powerful constraint for the study of galactic dynamics. We illustrate our method in two galaxies: NGC 4062 and NGC 5248. In both cases, we have detected trailing and leading m=2 waves with similar pitch angles. This suggests that the amplification mechanism is the WASER type II. In this mechanism, the bulge region reflects (rather than refracts) incoming waves with no cha...

  5. The Geometry of the Galaxy's Spiral Arms

    Science.gov (United States)

    Steiman-Cameron, Thomas Y.; Wolfire, M.; Hollenbach, D.

    2008-05-01

    We present a new model for the spiral structure of the Milky Way based upon an analysis of the essentially all-sky spectral data obtained by the Far Infrared Absolute Spectrophotometer (FIRAS) instrument of the Cosmic Background Explorer (COBE) satellite. The model provides the volume emissivities of the [C II] 128 µm and [N II] 205 µm lines, as a function of position within the Galaxy. These lines are important coolants of the interstellar medium and strong tracers of the spiral structure. Despite decades of work, there is still no full agreement on the number of spiral arms in the Milky Way, much less the details of their geometry. Motivated, in part, by this fact, we conducted a systematic search for 2-arm, 3-arm, and 4-arm models that maximize agreement with the COBE data. We find that only a four-arm model, with arms defined by logarithmic spiral forms and pitch angles ranging from 13.5 to 15.6 degrees, is consistent with the observations. The arms are neither evenly spaced nor identical in form. The resultant volume emissivity models for C+ and N+, when convolved with the FIRAS beam and integrated over the Galaxy, reproduce the COBE [C II] 128 µm and [N II] 205 µm intensity maps extremely well. We also examine all models for the Galaxy's spiral structure that have been proposed over the past half century in the context of the same COBE observations. A significant fraction of these models, including many recent ones, appear to be incompatible with the data. However, several four-arm models from the literature are consistent with the COBE observations.

  6. Multislice spiral CT of the paranasal sinuses; Mehrschicht-Spiral-CT der Nasennebenhoehlen: Erste Erfahrungen unter besonderer Beruecksichtigung der Strahlenexposition

    Energy Technology Data Exchange (ETDEWEB)

    Dammann, F.; Bode, A.; Heuschmid, M.; Kopp, A.; Georg, C.; Pereira, P.L.; Claussen, C.D. [Tuebingen Univ. (Germany). Radiologische Universitaetsklinik

    2000-08-01

    Purpose: To evaluate the potential of multislice CT in the diagnosis of the paranasal sinuses. Methods: Dose measurements were performed exposing an Alderson Rando phantom in a four-slice spiral CT (MS-CT) while applying a variety of scan parameters. Additionally, 30 consecutive patients underwent a transversal examination by the MS-CT using 1/1/3.5/0.5 mm spiral parameters and an additional transversal or coronal scan on a conventional single slice spiral CT (SS-CT) with 2/3/1 mm. Coronal reformations of the MS-CT were compared with the primary coronal SS-CT, or coronal reformations of the transversal SS-CT, respectively, with regard to image quality and depiction of relevant anatomical details of the region. Results: Superficial exposure values at the level of the eye lenses as well as for the thyroid gland were superior for MS-CT (3.62 mGy, and 0.12 mGy, resp.) as compared to SS-CT (2.96 mGy, and 0.07 mGy). Image quality was equal or superior for MS-CT as compared to SS-CT in all but one case. Drawbacks of SS-CT, such as dental amalgam artifacts, stair step artifacts or partial volume artifacts did not notably affect the coronal reformations of MS-CT. Conclusions: MS-CT seems to have the potential to replace primary coronal CT of the paranasal sinuses without any loss of image quality, but may even improve the overall diagnostic value. Radiation doses may still have to be reduced. (orig.) [German] Ziel: Erprobung eines Multislice-CT (MS-CT) zur Diagnostik der Nasennebenhoehlen (NNH). Methode: An einem Alderson Rando Phantom wurden Dosismessungen bei der Spiral-CT der NNH mit einem Mehrschicht-CT (MS-CT) unter Verwendung unterschiedlicher Scanparameter durchgefuehrt. Anschliessend wurden 30 konsekutive Patienten an dem MS-CT mit den Spiralparametern 1/1/3,5/0,5 mm und einem konventionellen Einzeilen Spiral-CT (SS-CT; 2/3/1 mm) untersucht. Die koronaren Rekonstruktionen der transversalen MS-CT wurden mit den koronaren Rekonstruktionen bzw. den primaeren koronaren

  7. SPIRAL DENSITY WAVES IN M81. II. HYDRODYNAMIC SIMULATIONS OF THE GAS RESPONSE TO STELLAR SPIRAL DENSITY WAVES

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Hsiang-Hsu; Lee, Wing-Kit; Taam, Ronald E.; Feng, Chien-Chang; Lin, Lien-Hsuan, E-mail: hhwang@asiaa.sinica.edu.tw [Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141, Taipei 10617, Taiwan, ROC (China)

    2015-02-20

    The gas response to the underlying stellar spirals is explored for M81 using unmagnetized hydrodynamic simulations. Constrained within the uncertainty of observations, 18 simulations are carried out to study the effects of self-gravity and to cover the parameter space comprising three different sound speeds and three different arm strengths. The results are confronted with the data observed at wavelengths of 8 μm and 21 cm. In the outer disk, the ring-like structure observed in the 8 μm image is consistent with the response of cold neutral medium with an effective sound speed 7 km s{sup –1}. For the inner disk, the presence of spiral shocks can be understood as a result of 4:1 resonances associated with the warm neutral medium with an effective sound speed 19 km s{sup –1}. Simulations with a single effective sound speed alone cannot simultaneously explain the structures in the outer and inner disks. Instead this justifies the coexistence of cold and warm neutral media in M81. The anomalously high streaming motions observed in the northeast arm and the outward shifted turning points in the iso-velocity contours seen along the southwest arm are interpreted as signatures of interactions with companion galaxies. The level of simulated streaming motions narrows down the uncertainty of the observed arm strength toward larger amplitudes.

  8. Safe Control for Spiral Recovery of Unmanned Aerial Vehicle

    Directory of Open Access Journals (Sweden)

    Chang-Jian Ru

    2014-01-01

    Full Text Available With unmanned aerial vehicles (UAVs widely used in both military and civilian fields, many events affecting their safe flying have emerged. That UAV’s entering into the spiral is such a typical safety issue. To solve this safety problem, a novel recovery control approach is proposed. First, the factors of spiral are analyzed. Then, based on control scheduling of state variables and nonlinear dynamic inversion control laws, the spiral recovery controller is designed to accomplish guidance and control of spiral recovery. Finally, the simulation results have illustrated that the proposed control method can ensure the UAV autonomous recovery from spiral effectively.

  9. Analysis of the spiral structure in a simulated galaxy

    CERN Document Server

    Mata-Chávez, Dolores; Puerari, Ivânio

    2014-01-01

    We analyze the spiral structure that results in a numerical simulation of a galactic disk with stellar and gaseous components evolving in a potential that includes an axisymmetric halo and bulge. We perform a second simulation without the gas component to observe how it affects the spiral structure in the disk. To quantify this, we use a Fourier analysis and obtain values for the pitch angle and the velocity of the self-excited spiral pattern of the disk. The results show a tighter spiral in the simulation with gaseous component. The spiral structure is consistent with a superposition of waves, each with a constant pattern velocity in given radial ranges.

  10. Oxygen and nitrogen abundances in Virgo and field spirals

    OpenAIRE

    Pilyugin, L. S.; Molla, Mercedes; Ferrini, Federico; Vilchez, Jose M.

    2001-01-01

    The oxygen and nitrogen abundances in the HII regions of the nine Virgo spirals of the sample from Skillman et al (1996) and in nine field spiral galaxies are re-determined with the recently suggested P - method. We confirm that there is an abundance segregation in the sample of Virgo spirals in the sense that the HI deficient Virgo spirals near the core of the cluster have higher oxygen abundances in comparison to the spirals at the periphery of the Virgo cluster. At the same time both the V...

  11. Breakup of Spiral Waves in Coupled Hindmarsh-Rose Neurons

    Institute of Scientific and Technical Information of China (English)

    MA Jun; JIA Ya; TANG Jun; YANG Li-Jian

    2008-01-01

    @@ Breakup of spiral wave in the Hindmarsh-Rose neurons with nearest-neighbour couplings is reported.Appropriate initial values and parameter regions are selected to develop a stable spiral wave and then the Gauesian coloured noise with different intensities and correlation times is imposed on all neurons to study the breakup of spiral wave, respectively.Based on the mean field theory, the statistical factor of synchronization is defined to analyse the evolution of spiral wave.It is found that the stable rotating spiral wave encounters breakup with increasing intensity of Gaussian coloured noise or decreasing correlation time to certain threshold.

  12. Decametre scale, spiral-shaped landforms in Elysium Planitia, Mars

    Science.gov (United States)

    Balme, M. R.; Gallagher, C.

    2012-04-01

    We present the discovery of a new type of landform that is apparently confined to one or two locations in western Elysium Planitia, Mars. In planview, these landforms consist of spirals, a few tens of metres across, defined by low furrows and ridges. They appear singly or in loose groups or chains and are generally double-armed with a visual similarity to Kelvin-Helmholtz instability forms. About 100 examples have been found, over 90% of which occur in a single image. Almost all the examples seen have "anti-clockwise" rotation (from the edge to the centre); less than a fifth spiral the other way. The spirals are found only in the polygonised elements of a terrain type known as Platy-Ridged-Polygonised (PRP) terrain. This distinctive surface displays a tripartite morphology comprising: 1) well-defined, kilometre-scale plates of rubbly material (clast-sizes up to a few meters in diameters), 2) complex patterns of sinuous to sub-linear rubbly ridges that are often many kilometres long, less than a few tens of metres across and less than a few metres in height, and 3) clast-free zones between the plates that display decametre scale polygonally patterned ground defined by networks of furrows and grooves. PRP terrain appears to represent the "frozen" remnants of a once liquid medium: it is extremely flat with margins defining an equipotential surface; infills craters and drapes low relief terrain; can be traced up through the 300 km long Athabasca Vallis outflow channel to a source region consisting of a pair of large (km-wide) fractures called the Cerberus Fossae. The origin of the PRP material is debated: some authors favour extremely fluid, voluminous and turbulently emplaced lavas (e.g. Keszthelyi et al., Geochem. Geophys. Geosys., 2003), others argue that this material represents a debris-covered relict frozen sea or ocean (e.g. Murray et al., Nature, 2005). The spirals, which are visible only in HiRISE images with sub-metre spatial resolution, have been observed in

  13. Validation of in vivo 2D displacements from spiral cine DENSE at 3T.

    Science.gov (United States)

    Wehner, Gregory J; Suever, Jonathan D; Haggerty, Christopher M; Jing, Linyuan; Powell, David K; Hamlet, Sean M; Grabau, Jonathan D; Mojsejenko, Walter Dimitri; Zhong, Xiaodong; Epstein, Frederick H; Fornwalt, Brandon K

    2015-01-30

    Displacement Encoding with Stimulated Echoes (DENSE) encodes displacement into the phase of the magnetic resonance signal. Due to the stimulated echo, the signal is inherently low and fades through the cardiac cycle. To compensate, a spiral acquisition has been used at 1.5T. This spiral sequence has not been validated at 3T, where the increased signal would be valuable, but field inhomogeneities may result in measurement errors. We hypothesized that spiral cine DENSE is valid at 3T and tested this hypothesis by measuring displacement errors at both 1.5T and 3T in vivo. Two-dimensional spiral cine DENSE and tagged imaging of the left ventricle were performed on ten healthy subjects at 3T and six healthy subjects at 1.5T. Intersection points were identified on tagged images near end-systole. Displacements from the DENSE images were used to project those points back to their origins. The deviation from a perfect grid was used as a measure of accuracy and quantified as root-mean-squared error. This measure was compared between 3T and 1.5T with the Wilcoxon rank sum test. Inter-observer variability of strains and torsion quantified by DENSE and agreement between DENSE and harmonic phase (HARP) were assessed by Bland-Altman analyses. The signal to noise ratio (SNR) at each cardiac phase was compared between 3T and 1.5T with the Wilcoxon rank sum test. The displacement accuracy of spiral cine DENSE was not different between 3T and 1.5T (1.2 ± 0.3 mm and 1.2 ± 0.4 mm, respectively). Both values were lower than the DENSE pixel spacing of 2.8 mm. There were no substantial differences in inter-observer variability of DENSE or agreement of DENSE and HARP between 3T and 1.5T. Relative to 1.5T, the SNR at 3T was greater by a factor of 1.4 ± 0.3. The spiral cine DENSE acquisition that has been used at 1.5T to measure cardiac displacements can be applied at 3T with equivalent accuracy. The inter-observer variability and agreement of DENSE-derived peak strains and

  14. Spiral analysis-improved clinical utility with center detection.

    Science.gov (United States)

    Wang, Hongzhi; Yu, Qiping; Kurtis, Mónica M; Floyd, Alicia G; Smith, Whitney A; Pullman, Seth L

    2008-06-30

    Spiral analysis is a computerized method that measures human motor performance from handwritten Archimedean spirals. It quantifies normal motor activity, and detects early disease as well as dysfunction in patients with movement disorders. The clinical utility of spiral analysis is based on kinematic and dynamic indices derived from the original spiral trace, which must be detected and transformed into mathematical expressions with great precision. Accurately determining the center of the spiral and reducing spurious low frequency noise caused by center selection error is important to the analysis. Handwritten spirals do not all start at the same point, even when marked on paper, and drawing artifacts are not easily filtered without distortion of the spiral data and corruption of the performance indices. In this report, we describe a method for detecting the optimal spiral center and reducing the unwanted drawing artifacts. To demonstrate overall improvement to spiral analysis, we study the impact of the optimal spiral center detection in different frequency domains separately and find that it notably improves the clinical spiral measurement accuracy in low frequency domains.

  15. NMR of unfolded proteins

    Indian Academy of Sciences (India)

    Amarnath Chtterjee; Ashutosh Kumar; Jeetender Chugh; Sudha Srivastava; Neel S Bhavesh; Ramakrishna V Hosur

    2005-01-01

    In the post-genomic era, as more and more genome sequences are becoming known and hectic efforts are underway to decode the information content in them, it is becoming increasingly evident that flexibility in proteins plays a crucial role in many of the biological functions. Many proteins have intrinsic disorder either wholly or in specific regions. It appears that this disorder may be important for regulatory functions of the proteins, on the one hand, and may help in directing the folding process to reach the compact native state, on the other. Nuclear magnetic resonance (NMR) has over the last two decades emerged as the sole, most powerful technique to help characterize these disordered protein systems. In this review, we first discuss the significance of disorder in proteins and then describe the recent developments in NMR methods for their characterization. A brief description of the results obtained on several disordered proteins is presented at the end.

  16. The formation of molecular clouds in spiral galaxies

    CERN Document Server

    Dobbs, C L

    2006-01-01

    We present Smoothed Particle Hydrodynamics (SPH) simulations of molecular cloud formation in spiral galaxies. These simulations model the response of a non-self-gravitating gaseous disk to a galactic potential. The formation of molecular gas occurs when cold ($T \\le 100$ K) gas is compressed during the passage of a spiral arm. The spiral arms display considerable structure and the molecular gas accumulates into dense clouds. We identify the formation of these structures as due to the dynamics of clumpy shocks, which perturb the orbits of particles passing through the spiral arm. In addition, the spiral shocks induce a large velocity dispersion in the spiral arms, comparable with the magnitude of the velocity dispersion observed in molecular clouds. The molecular clouds are largely confined to the spiral arms, since most molecular gas is photodissociated to atomic hydrogen upon leaving the arms. However a low photodissociation rate increases the amount of interarm molecular gas, and the possibility of molecula...

  17. Magnetic structure of the low-dimensional magnet NaCu{sub 2}O{sub 2}: {sup 63,65}Cu and {sup 23}Na NMR studies

    Energy Technology Data Exchange (ETDEWEB)

    Sadykov, A. F., E-mail: sadykov@imp.uran.ru; Gerashchenko, A. P.; Piskunov, Yu. V.; Ogloblichev, V. V.; Smol’nikov, A. G.; Verkhovskii, S. V.; Buzlukov, A. L.; Arapova, I. Yu. [Russian Academy of Sciences, Institute of Metal Physics, Ural Branch (Russian Federation); Furukawa, Y. [Iowa State University, Ames Laboratory (United States); Yakubovskii, A. Yu. [National Research Centre Kurchatov Institute (Russian Federation); Bush, A. A. [Moscow State Technical University of Radio Engineering, Electronics, and Automation (Russian Federation)

    2014-11-15

    The magnetic structure of a quasi-one-dimensional frustrated NaCu{sub 2}O{sub 2} magnet single crystal is studied by NMR. The spatial orientation of the planar spin spirals in the copper-oxygen Cu{sup 2+}-O chains is determined, and its evolution as a function of the applied magnetic field direction is analyzed.

  18. NMR studies of metalloproteins

    OpenAIRE

    Li, H; H. Sun

    2011-01-01

    Metalloproteins represent a large share of the proteomes, with the intrinsic metal ions providing catalytic, regulatory, and structural roles critical to protein functions. Structural characterization of metalloproteins and identification of metal coordination features including numbers and types of ligands and metal-ligand geometry, and mapping the structural and dynamic changes upon metal binding are significant for understanding biological functions of metalloproteins. NMR spectroscopy has...

  19. CT血管造影三维重建对脊柱侧弯矫形手术的临床应用研究%Study on the Clinical Application of the Imaging Technique Combined Spiral CT 3-Dreconstruction with CTA for the Correction Operation of Scoliosis

    Institute of Scientific and Technical Information of China (English)

    刘刚; 卓佳驹

    2012-01-01

    [Purpose] To evaluate the clinical applications of imaging technique combined spiral CT 3-Dreconstruc-tion with CTA for the correction operation of scoliosis. [Materials and Methods] 42 patients with scoliosis had been performed both plain and enhanced CT scanning .Using CTA and 3-D reconstructions combined technique to reconstruct the imaging of the correlative part of the correction operation of scoliosis of the 42 patients, then evaluat-ing its advantage by means of contrasting to MIP, MPR/CPR, SSD, 3-D bone reconstructions. Attempt to simulate the implantation of the vertebrae screw used for anterior instrumentation surgery in the workstation and measure the length of the concomitant aorta of the spinal column which needs to be corrected. [Results] Using CTA and 3-D reconstructions combined technique to successfully reconstruct the imaging which can synchronously and three-di-mensionally display the malformed spinal column, aorta and other concomitant organ of the correlative part of the correction operation of scoliosis of the 42 patients. This imaging has taken on distinct predominance in synchronously and three-dimensionally displaying the malformed spinal column and its circumjacent soft tissue. Applying this tech-nique can triumphantly simulate the screw implant of anterior instrumentation surgery and can measure and work out the length of the aorta abutting upon the malformed spinal column. [Conclusion] Imaging achieved from the tech-nique combined spiral CT 3D-reconstruction with CTA can synchronously and three-dimensionally display mal-formed spinal column, aorta and other concomitant organ and can provide imagology reference for surgical planning to avoid aorta damage and to ensure surgical security.%【目的】探讨MDCTA对脊柱侧弯矫形手术的临床应用价值。【材料与方法】对42例脊柱侧弯患者术前行全脊柱螺旋CT平扫及CTA检查,利用螺旋CT血管造影三维重建技术(VR法)对脊柱侧弯矫形手术相

  20. The central region of spiral galaxies as seen by Herschel. M81, M99 and M100

    CERN Document Server

    Sauvage, M; Bendo, G J; Boselli, A; Pohlen, M; Wilson, C D; Auld, R; Baes, M; Barlow, M J; Bock, J J; Bradford, M; Buat, V; Castro-Rodriguez, N; Chanial, P; Charlot, S; Ciesla, L; Clements, D L; Cooray, A; Cormier, D; Cortese, L; Davies, J I; Dwek, E; Eales, S A; Elbaz, D; Galametz, M; Galliano, F; Gear, W K; Glenn, J; Gomez, H L; Griffin, M; Hony, S; Isaak, K G; Levenson, L R; Lu, N; Madden, S C; O'Halloran, B; Okumura, K; Oliver, S; Page, M J; Panuzzo, P; Papageorgiou, A; Parkin, T J; Perez-Fournon, I; Rangwala, N; Rigby, E E; Roussel, H; Rykala, A; Schulz, B; Schirm, M R P; Smith, M W L; Spinoglio, L; Stevens, J A; Srinivasan, S; Symeonidis, M; Trichas, M; Vaccari, M; Vigroux, L; Wozniak, H; Wright, G S; Zeilinger, W W

    2010-01-01

    With appropriate spatial resolution, images of spiral galaxies in thermal infrared (~10 micron and beyond) often reveal a bright central component, distinct from the stellar bulge, superimposed on a disk with prominent spiral arms. ISO and Spitzer studies have shown that much of the scatter in the mid-infrared colors of spiral galaxies is related to changes in the relative importance of these two components, rather than to other modifications, such as the morphological type or star formation rate, that affect the properties of the galaxy as a whole. With the Herschel imaging capability from 70 to 500 micron, we revisit this two-component approach at longer wavelengths, to see if it still provides a working description of the brightness distribution of galaxies, and to determine its implications on the interpretation of global far-infrared properties of galaxies.

  1. 64排螺旋CT诊断成人门静脉海绵样变性的影像学表现及价值%Imaging Findings and Value of 64-slice Spiral CT in Diagnosis of Cavernous Transformation of Portal Vein

    Institute of Scientific and Technical Information of China (English)

    施健; 施小平; 王强; 王勤英

    2012-01-01

    目的 探讨利用64排螺旋CT动态增强扫描技术及多种血管重建方法诊断门静脉海绵样变性(Cavernous transformation of portal vein,CTPV)的价值和意义.方法 10例经手术、数字血管造影、超声诊断证实的门静脉海绵样变性病例,均行腹部平扫和动态增强扫描及血管后处理成像.结果 门静脉海绵样变性主要表现为门脉主干和(或)分支的阻塞,门脉走行区正常结构消失,出现大量向肝性及离肝性侧枝静脉.通过VR、MIP、MPR等血管成像技术能很好的显示门静脉栓塞、侧枝血管的重建与开放情况.结论 64排螺旋CT动态增强扫描及血管成像技术对诊断门静脉海绵样变性及侧枝血管的显示有较大优势和意义.%Objective To evaluate 64-slice spiral CT dynamic contrast-enhanced scanning combined with angiography reconstruction techniques in diagnosis of cavernous transformation of portal vein (CTPV). Methods 10 patients with CTPV conformed by surgery, digital angiography and ultrasound underwent plain and dynamic contrast enhanced CT. Multiple angiography reconstruction techniques were used to obtain vascular post-processing images. Results CTPV was primarily characteristic of the portal vein and (or) branch obstruction, loss of normal structure of portal vein region, presence of abundant venous collaterals through and out of liver. Volume rendering view (VR), maximum intensity projection (MIP) and multiplanar reconstruction (MPR) could distinctly display the portal vein embolization as well as reconstruction and opening situation of collateral vessels. Conclusion 64-slice spiral CT dynamic contrast-enhanced scanning combined with angiography reconstruction techniques is capable of making an accurate diagnosis of CTPV and providing more information for clinical therapy decisions.

  2. Prediction of Starch, Soluble Sugars and Amino Acids in Potatoes (Solanum tuberosum L.) Using Hyperspectral Imaging, Dielectric and LF-NMR Methodologies

    DEFF Research Database (Denmark)

    Kjær, Anders; Nielsen, Glenn; Stærke, Søren

    2016-01-01

    was designed to evaluate five different scanning methods for their potential use in potato assessment and sorting. Two methods were based on hyperspectral imaging, two were based on dielectric/bio-impedance and one was based on low-field nuclear magnetic resonance. A set of 60 potatoes of 10 different......, conductivity of pressed cell sap and cell sizes. Results showed that most types of spectral analyses had relatively high potential for predicting the starch-related parameters and medium potential for predicting the concentration of the reducing sugars fructose and glucose. Most methods showed medium potential...... for prediction of several amino acids, including asparagine, which showed particularly promising predictions in the hyperspectral analyses of intact potatoes. The presented screening study enabled us to perform robust choices for the further development and optimization of the methods and instruments...

  3. UIT Ultraviolet Surface Photometry of the Spiral Galaxy M74

    Science.gov (United States)

    Cornett, R. H.; Greason, M. R.; Offenberg, J. D.; Bohlin, R. C.; Cheng, K. P.; O'Connell, R. W.; Roberts, M. R.; Smith, A. M.; Smith, E. P.; Angione, R. J.; Talbert, F. D.; Stecher, T. P.

    1993-05-01

    UV photometry from Ultraviolet Imaging Telescope (UIT) images at 1520 Angstroms (magnitudes mbone) and 2490 Angstroms (maone) of the spiral galaxy M74 (NGC628) is compared with ha, R, V, and B surface photometry and models. M74's surface brightness profiles have central peaks with exponential falloffs; the profiles' exponential scale lengths increase with decreasing continuum wavelength. The slope of the continuum-subtracted ha profile is between those of FUV and NUV profiles, consistent with related origins of ha and UV emission in extreme Population I material. M74's color profiles have small gradients, all becoming bluer with increasing radius. The UIT color (mbone-maone) averages near 0.0, the color of an A0 star, over the central 20 arcsec radius, and slopes from ~ -0.2 to ~ -0.4 from 20 to 200 arcsec. Spiral arms dominate surface photometry colors; interarm regions are slightly redder. In the UV, M74's nuclear region resembles disk/spiral arm material in color and morphology, unlike M81. (mbone-maone) colors and models of M74's central region clearly demonstrate that there are no O or B stars in the central 10 arcsec. M74's (mbone-maone) profile is similar to M33's but is ~ 0.5 mag redder. M74 is ~ 0.4 mag bluer than M81 in its outer disk. We investigate explanations for both the color profiles and the differences among the galaxies. M74's maone-V and mbone-V color profiles cannot be explained by a disk of uniform color behind a screen of dust with a known reddening function, distributed like the neutral gas with a fixed gas-to-dust ratio. Known abundance variations could produce the observed color gradient in M74; however, evolutionary cluster models show that sensible time parameters, including star formation start time and exponential decay rate, also produce the observed colors of M74, M33, and M81.

  4. Comparison of image quality and radiation dose between high-pitch mode and low-pitch mode spiral chest CT in small uncooperative children: The effect of respiratory rate

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Seong Ho; Choi, Young Hun; Cho, Hyun-Hae; Lee, So Mi [Seoul National University Hospital, Seoul National University College of Medicine, Department of Radiology, Seoul (Korea, Republic of); Shin, Su-Mi [SMG-SNU Boramae Medical Center, Department of Radiology, Seoul (Korea, Republic of); Cheon, Jung-Eun; Kim, Woo Sun; Kim, In-One [Seoul National University Hospital, Seoul National University College of Medicine, Department of Radiology, Seoul (Korea, Republic of); Seoul National University Medical Research Center, Institute of Radiation Medicine, Seoul (Korea, Republic of)

    2016-04-15

    To compare image quality and radiation dose between high-pitch mode (HPM) and low-pitch mode (LPM) CT in young children. Forty-seven children (mean age 35.6 months; range, 0-126 months) underwent 49 CT examinations in HPM or LPM and were divided into high or low respiratory rate (RR) groups. A qualitative image quality was compared between the two modes. The volume CT dose index (CTDI{sub vol}) and dose-length product (DLP) were evaluated from the dose reports, and effective doses were assessed using a paediatric phantom. Image quality was generally better for HPM than LPM (diagnostic acceptance score, 4.00 vs. 3.46, P = 0.004); the difference was more prominent in the high RR group (4.00 vs. 3.22, P = 0.001). However, there was no significant difference in the low RR group. The mean DLP value was higher in HPM than LPM (29.48 mGy . cm vs. 23.46 mGy . cm, P = 0.022), while CTDI{sub vol} was not significantly different. The total effective radiation dose was 26 % higher in HPM than LPM (1.82 mSv vs. 1.44 mSv). LPM can be considered for paediatric lung evaluation in young children with low RRs to reduce radiation dose while maintaining favourable image quality. (orig.)

  5. Determining Star Formation Timescale and Pattern Speed in Nearby Spiral Galaxies

    CERN Document Server

    Egusa, Fumi; Sofue, Yoshiaki; Nakanishi, Hiroyuki; Komugi, Shinya

    2009-01-01

    We present a revised method for simultaneous determination of the pattern speed and star formation timescale of spiral galaxies, its application, and results for CO and Ha images of nearby spiral galaxies. Out of 13 galaxies, we were able to derive the 2 parameters for 5 galaxies. We categorize them as "C" galaxies, and find (1) The corotation radius is close to the edge of the CO data, and is about half of the optical radius for 3 galaxies. (2) The star formation timescale is roughly consistent with the free-fall time of typical molecular clouds, which indicates that the gravitational instability is the dominant mechanism triggering star formation in spiral arms. (3) The timescale is found to be almost independent of surface density of molecular gas, metallicity, or spiral arm strengths. The number of "C" galaxies and the quality of CO data, however, are not enough to confirm these relationships. We also find that 2 other galaxies show no offsets between CO and Ha, although their arms are clearly traced, and...

  6. The Black Hole Mass - Pitch Angle Relation of Type I AGN In Spiral Galaxies

    Science.gov (United States)

    Schilling, Amanda; Jones, Logan; Hughes, John A.; Barrows, R. Scott; Kennefick, Julia D.

    2017-01-01

    A relationship between the mass of supermassive black holes, M, at the center of galaxies and the pitch angle, P, a measure of tightness of spiral arms, was recently reported by Berrier, et al. (2013 ApJ 769, 132) for late type galaxies. The relationship, established for a local sample, shows that spiral galaxies with tighter pitch angles host higher mass black holes. In this work, we explore the M-P relation for a sample of 50 low to moderate redshift (0.04spiral galaxies that host Type 1 Active Galactic Nuclei, AGN. These objects were selected from the SDSS quasar catalog and various studies involving HST imaging. Broad Hβ, Hα, and MgII and narrow [OIII]λ5007 emission lines were used with established mass scaling relations to estimate black-hole mass. Pitch angles were measured using a 2DFFT technique (Davis, et al., 2012 ApJS 199, 33). We find that the M-P relation for the higher redshift, AGN sample differs from that of the local sample and discuss the possibility of AGN feedback by looking at a proposed Fundamental Plane for late-type galaxies - a correlation between bulge mass, disk mass, and spiral-arm pitch angle (Davis, et al. 2015, ApJ 802, L13).

  7. H{\\alpha} Kinematics of S4G spiral galaxies I. NGC 864

    CERN Document Server

    Erroz-Ferrer, Santiago; Font, Joan; Beckman, John E; Falcón-Barroso, Jesús; Sánchez-Gallego, José Ramón; Athanassoula, E; Bosma, Albert; Gadotti, Dimitri A; Muñoz-Mateos, Juan Carlos; Sheth, Kartik; Buta, Ronald J; Comerón, Sébastien; de Paz, Armando Gil; Hinz, Joannah L; Ho, Luis C; Kim, Taehyun; Laine, Jarkko; Laurikainen, Eija; Madore, Barry F; Menéndez-Delmestre, Karín; Mizusawa, Trisha; Regan, Michael W; Salo, Heikki; Seibert, Mark

    2012-01-01

    We present a study of the kinematics of the isolated spiral galaxy NGC 864, using H{\\alpha} Fabry-Perot data obtained with the GH{\\alpha}FaS instrument at the William Herschel Telescope in La Palma, complemented with images at 3.6 {\\mu}m, in the R band and in H{\\alpha} filter, and integral field spectroscopic data. The resulting data cubes and velocity maps allow the study of the kinematics of the galaxy, including in-depth investigations of the rotation curve, velocity moment maps, velocity residual maps, gradient maps and position-velocity diagrams. We find asymmetries in the velocity field in the bar zone, caused by non-circular motions, probably in response to the potential of the bar. We also find a flat-profile bar, in agreement with the strong bar, with the grand design spiral pattern, and with the gap between the ends of the bar and the start of the spiral arms. We quantify the rate of massive star formation, which is concentrated in the two spiral arms.

  8. Status of the SPIRAL2 injector commissioning

    Energy Technology Data Exchange (ETDEWEB)

    Thuillier, T., E-mail: thuillier@lpsc.in2p3.fr; Angot, J.; Jacob, J.; Lamy, T.; Sole, P. [LPSC, Université Grenoble Alpes, CNRS/IN2P3, 53 rue des Martyrs, 38026 Grenoble Cedex (France); Barué, C.; Bertrand, P.; Canet, C.; Ferdinand, R.; Flambard, J.-L.; Jardin, P.; Lemagnen, F.; Maunoury, L.; Osmond, B. [GANIL, CNRS/IN2P3, Bvd Henri Becquerel, BP 55027, 14076 Caen Cedex 5 (France); Biarrotte, J. L. [IPN Orsay, Université Paris Sud, CNRS/IN2P3, 15 rue Georges Clémenceau, 91406 Orsay Cedex (France); Denis, J.-F.; Roger, A.; Touzery, R.; Tuske, O.; Uriot, D. [Irfu, CEA Saclay, DSM/Irfu/SACM, 91191 Gif Sur Yvette (France); and others

    2016-02-15

    The SPIRAL2 injector, installed in its tunnel, is currently under commissioning at GANIL, Caen, France. The injector is composed of two low energy beam transport lines: one is dedicated to the light ion beam production, the other to the heavy ions. The first light ion beam, created by a 2.45 GHz electron cyclotron resonance ion source, has been successfully produced in December 2014. The first beam of the PHOENIX V2 18 GHz heavy ion source was analyzed on 10 July 2015. A status of the SPIRAL2 injector commissioning is given. An upgrade of the heavy ion source, named PHOENIX V3 aimed to replace the V2, is presented. The new version features a doubled plasma chamber volume and the high charge state beam intensity is expected to increase by a factor of 1.5 to 2 up to the mass ∼50. A status of its assembly is proposed.

  9. Discontinuous Spirals of Stable Periodic Oscillations

    DEFF Research Database (Denmark)

    Sack, Achim; Freire, Joana G.; Lindberg, Erik

    2013-01-01

    We report the experimental discovery of a remarkable organization of the set of self-generated periodic oscillations in the parameter space of a nonlinear electronic circuit. When control parameters are suitably tuned, the wave pattern complexity of the periodic oscillations is found to increase...... orderly without bound. Such complex patterns emerge forming self-similar discontinuous phases that combine in an artful way to produce large discontinuous spirals of stability. This unanticipated discrete accumulation of stability phases was detected experimentally and numerically in a Duffing-like proxy...... specially designed to bypass noisy spectra conspicuously present in driven oscillators. Discontinuous spirals organize the dynamics over extended parameter intervals around a focal point. They are useful to optimize locking into desired oscillatory modes and to control complex systems. The organization...

  10. Modes Of The Spiral Clock Gong

    Science.gov (United States)

    Perrin, R.; Charnley, T.; Swallowe, G. M.; Banu, H.

    1993-03-01

    The modal frequencies of a spiral clock gong have been measured. The mode numbers and forms of vibrations have been identified by finite element modelling and photographic techniques; very good agreement between modelling and experiment was achieved. All modes were found to be either purely in-plane or out-of-plane. In both cases plots of log (2 n - 1) vs. log ƒ yielded curves with two distinct regions, the transition occurring where the wavelength corresponded to one turn of the spiral. Both sets of lower modes were very complex but the modal frequencies above n = 11 were found to fit a modified form of Chladni's law. It is suggested that the modified Chladni law may form the basis of many musical sounds.

  11. Spiral precipitation patterns in confined chemical gardens.

    Science.gov (United States)

    Haudin, Florence; Cartwright, Julyan H E; Brau, Fabian; De Wit, A

    2014-12-09

    Chemical gardens are mineral aggregates that grow in three dimensions with plant-like forms and share properties with self-assembled structures like nanoscale tubes, brinicles, or chimneys at hydrothermal vents. The analysis of their shapes remains a challenge, as their growth is influenced by osmosis, buoyancy, and reaction-diffusion processes. Here we show that chemical gardens grown by injection of one reactant into the other in confined conditions feature a wealth of new patterns including spirals, flowers, and filaments. The confinement decreases the influence of buoyancy, reduces the spatial degrees of freedom, and allows analysis of the patterns by tools classically used to analyze 2D patterns. Injection moreover allows the study in controlled conditions of the effects of variable concentrations on the selected morphology. We illustrate these innovative aspects by characterizing quantitatively, with a simple geometrical model, a new class of self-similar logarithmic spirals observed in a large zone of the parameter space.

  12. Status of the SPIRAL2 injector commissioning

    Science.gov (United States)

    Thuillier, T.; Angot, J.; Barué, C.; Bertrand, P.; Biarrotte, J. L.; Canet, C.; Denis, J.-F.; Ferdinand, R.; Flambard, J.-L.; Jacob, J.; Jardin, P.; Lamy, T.; Lemagnen, F.; Maunoury, L.; Osmond, B.; Peaucelle, C.; Roger, A.; Sole, P.; Touzery, R.; Tuske, O.; Uriot, D.

    2016-02-01

    The SPIRAL2 injector, installed in its tunnel, is currently under commissioning at GANIL, Caen, France. The injector is composed of two low energy beam transport lines: one is dedicated to the light ion beam production, the other to the heavy ions. The first light ion beam, created by a 2.45 GHz electron cyclotron resonance ion source, has been successfully produced in December 2014. The first beam of the PHOENIX V2 18 GHz heavy ion source was analyzed on 10 July 2015. A status of the SPIRAL2 injector commissioning is given. An upgrade of the heavy ion source, named PHOENIX V3 aimed to replace the V2, is presented. The new version features a doubled plasma chamber volume and the high charge state beam intensity is expected to increase by a factor of 1.5 to 2 up to the mass ˜50. A status of its assembly is proposed.

  13. Modelling Neutral Hydrogen Discs of Spiral Galaxies

    Institute of Scientific and Technical Information of China (English)

    林伟鹏; 洪碧海

    2002-01-01

    We present an analytical model of a neutral hydrogen disc in a spiral galaxy. The gas disc of the spiral galaxy isassumed to have an exponential surface density profile and to be ionized by the cosmic ultraviolet background.To compare with observations, we consider the disc position angle and inclination angle for a line of sight goingthrough the galaxy disc. The HI column densities depend on the strength of ionizing field and disc position andinclination. The model was applied to NGC 3198 and the results were compared with observational data. TheHI disc profile at large disc radii can be tested by further HI observations using radio telescopes with a largeraperture than the present facilities. This HI disc model can be used to predict quasar absorption line systems bygalaxy discs if quasar lines of sight go through the discs.

  14. Understanding the transformation of spirals to lenticulars

    CERN Document Server

    Johnston, Evelyn J; Merrifield, Michael R

    2014-01-01

    By studying the individual star-formation histories of the bulges and discs of lenticular (S0) galaxies, it is possible to build up a sequence of events that leads to the cessation of star formation and the consequent transformation from the progenitor spiral. In order to separate the bulge and disc stellar populations, we spectroscopically decomposed long-slit spectra of Virgo Cluster S0s into bulge and disc components. Analysis of the decomposed spectra shows that the most recent star formation activity in these galaxies occurred within the bulge regions, having been fuelled by residual gas from the disc. These results point towards a scenario where the star formation in the discs of spiral galaxies are quenched, followed by a final episode of star formation in the central regions from the gas that has been funnelled inwards through the disc.

  15. Application study of multilayer spiral CT perfusion imaging in differential diagnosis of solitary pulmonary nodules%多层螺旋CT灌注成像在孤立性肺结节鉴别诊断中的应用研究

    Institute of Scientific and Technical Information of China (English)

    张伟恒; 滕问天; 石伟辉

    2014-01-01

    目的:研究应用多层螺旋CT鉴别诊断孤立性肺结节的价值。方法行全肺平扫,平扫层厚5mm;随后将最大的结节病灶选定,行HRCT扫描,层厚1~2mm,并同时开始扫描以及灌注。结果良性SPN、炎性SPN以及恶性SPN患者的灌注成像结果并不一致,其中PS、BF以及BV存在显著性差异(P<0.05),MTT的差异不明显(P>0.05)。结论在对良性SPN、炎性SPN以及恶性SPN进行诊断鉴别的过程中,CT灌注成像技术能够发挥重要作用。%Objective To study the application value of multilayer spiral CT in the identification and diagnosis of solitary pulmonary nodules(SPN). Methods The whole lung plain scan was conducted and the layer thickness of plain scan was 5 mm. Then the largest nodule lesion was selected to receive HRCT scan and the layer thickness was 1-2 mm. Scan and perfusion were conducted at the same time. Results The patients with benign SPN, inflammatory SPN and malignant SPN did not have consistent perfusion imaging results, of which PS, BF and BV had significant differences(P0.05). Conclusion In the diagnosis and identification of benign SPN, inflammatory SPN and malignant SPN, CT perfusion imaging technique can play an important role.

  16. Virtual and three-dimensional bronchoscopy with spiral and electron beam computed tomography; Virtuelle und dreidimensionale Bronchoskopie mit Spiral- und Elektronenstrahl-Computertomographie

    Energy Technology Data Exchange (ETDEWEB)

    Schoepf, U.J.; Seemann, M.; Bruening, R.D.; Becker, C.; Gebicke, K.; Reiser, M.F. [Klinikum Grosshadern, Muenchen (Germany). Inst. fuer Radiologische Diagnostik; Schuhmann, D.; Haubner, M.; Krapichler, C.; Englmeier, K.H. [Gesellschaft fuer Strahlen- und Umweltforschung mbH Muenchen, Neuherberg (Germany). Inst. fuer Medizinische Informatik und Systemforschung (Medis); Schwaiblmair, M.; Knez, A.; Vogelmeier, C.; Haberl, R. [Klinikum Grosshadern, Muenchen (Germany). Medizinische Klinik 1; Mueller, C. [Klinikum Grosshadern, Muenchen (Germany). Chirurgische Klinik

    1998-10-01

    Purpose: To compare spiral computed tomography (CT) and electron-beam CT (EBT) for 3D and virtual CT-bronchoscopy. Materials and methods: 17 patients with various disorders of the tracheobronchial system were examined using fiberoptic bronchoscopy, spiral CT and EBT. 3D images were reconstructed from CT data sets using automated segmentation based on volume-growing methods. Surface-rendered, volume-rendered, and hybrid reconstructions were visualized in real time using a data helmet. Results: All data sets could be processed to high-quality three-dimensional (3D) and virtual reconstructions. The reduction of motion artifacts due to shorter scan times made EBT data sets better suited for automated segmentation and less susceptible to motion artifacts. 3D and virtual reconstructions did not increase the diagnostic sensitivity of CT compared to axial reconstructions alone. Conclusions: Shorter scan times of CT imaging yield higher-quality 3D and virtual reconstructions. Modern reconstruction techniques are valuable visualization tools for select indications and are the prerequisite for future developments in computer-aided medicine. (orig.) [Deutsch] Spiral-CT und Elektronenstrahlcomputertomographie (EBT) sollten hinsichtlich ihrer Eignung fuer die 3D und virtuelle CT-Bronchoskopie verglichen werden. 17 Patienten mit pathologischen Veraenderungen des Bronchialsystems wurden mit fiberoptischer Bronchoskopie sowie Spiral-CT oder EBT untersucht. Die CT-Datensaetze wurden mit automtisierten Segmentationsverfahren zu 3D Oberflaechenrekonstruktionen bzw. zu Volumenrekonstruktionen und zu hybriden Darstellungsformen weiterverarbeitet. Die virtuelle Visualisierung erfolgte ueber einen Datenhelm in Echtzeit. Alle Datensaetze konnten zu raeumlichen Rekonstruktionen guter Qualitaet weiterverarbeitet werden. Aufgrund der kuerzeren Scanzeiten waren die EBT-Datensaetze besser fuer die automatisierte Segmentation und fuer eine artefaktarme Rekonstruktion geeignet. Die diagnostische

  17. Self-Destructing Spiral Waves: Global Simulations of a Spiral Wave Instability in Accretion Disks

    CERN Document Server

    Bae, Jaehan; Hartmann, Lee; Richard, Samuel

    2016-01-01

    We present results from a suite of three-dimensional global hydrodynamic simulations which show that spiral density waves propagating in circumstellar disks are unstable to the growth of a parametric instability that leads to break-down of the flow into turbulence. This spiral wave instability (SWI) arises from a resonant interaction between pairs of inertial waves, or inertial-gravity waves, and the background spiral wave. The development of the instability in the linear regime involves the growth of a broad spectrum of inertial modes, with growth rates on the order of the orbital time, and results in a nonlinear saturated state in which turbulent velocity perturbations are of a similar magnitude to those induced by the spiral wave. The turbulence induces angular momentum transport, and vertical mixing, at a rate that depends locally on the amplitude of the spiral wave (we obtain a stress parameter $\\alpha \\sim 5 \\times 10^{-4}$ in our reference model). The instability is found to operate in a wide-range of ...

  18. Mathematical Modeling of Spiral Heat Exchanger

    OpenAIRE

    Probal Guha , Vaishnavi Unde

    2014-01-01

    Compact Heat Exchangers (CHEs) are increasingly being used on small and medium scale industries. Due to their compact size and efficient design, they facilitate more efficient heat transfer. Better heat transfer would imply lesser fuel consumption for the operations of the plant, giving improvement to overall efficiency. This reduction in consumption of fuel is a step towards sustainable development. This report exclusively deals with the study the spiral heat ...

  19. A spiral antenna sandwiched by dielectric layers

    OpenAIRE

    Nakano, Hisamatsu; Ikeda, Masakazu; Hitosugi, Kazuo; Yamauchi, Junji

    2004-01-01

    An infinitesimally thin spiral antenna, sandwiched by bottom and top dielectric layers having the same relative permittivity, is analyzed under the condition that the dielectric layers are of finite extent and the antenna is backed by an infinite conducting plane. As the thickness of the top dielectric layer increases, the input impedance and axial ratio (AR) vary in an oscillatory fashion, with a period slightly larger than one-half of the guided wavelength of a wave propagating in an unboun...

  20. Spiral inflation with Coleman-Weinberg potential

    Science.gov (United States)

    Barenboim, Gabriela; Park, Wan-Il

    2015-03-01

    We apply the idea of spiral inflation to the Coleman-Weinberg potential and show that inflation matching our observations well is allowed for a symmetry-breaking scale ranging from an intermediate scale to a grand unified theory (GUT) scale even if the quartic coupling λ is of O (0.1 ). The tensor-to-scalar ratio can be of O (0.01 ) in the case of GUT-scale symmetry breaking.