Sample records for absorption edge imaging

  1. Spectral K-edge subtraction imaging

    NASA Astrophysics Data System (ADS)

    Zhu, Y.; Samadi, N.; Martinson, M.; Bassey, B.; Wei, Z.; Belev, G.; Chapman, D.

    2014-05-01

    We describe a spectral x-ray transmission method to provide images of independent material components of an object using a synchrotron x-ray source. The imaging system and process is similar to K-edge subtraction (KES) imaging where two imaging energies are prepared above and below the K-absorption edge of a contrast element and a quantifiable image of the contrast element and a water equivalent image are obtained. The spectral method, termed ‘spectral-KES’ employs a continuous spectrum encompassing an absorption edge of an element within the object. The spectrum is prepared by a bent Laue monochromator with good focal and energy dispersive properties. The monochromator focuses the spectral beam at the object location, which then diverges onto an area detector such that one dimension in the detector is an energy axis. A least-squares method is used to interpret the transmitted spectral data with fits to either measured and/or calculated absorption of the contrast and matrix material-water. The spectral-KES system is very simple to implement and is comprised of a bent Laue monochromator, a stage for sample manipulation for projection and computed tomography imaging, and a pixelated area detector. The imaging system and examples of its applications to biological imaging are presented. The system is particularly well suited for a synchrotron bend magnet beamline with white beam access.

  2. Imaging at an x-ray absorption edge using free electron laser pulses for interface dynamics in high energy density systems [Resonant phase contrast imaging for interface physics

    DOE PAGES

    Beckwith, M. A.; Jiang, S.; Schropp, A.; ...

    2017-05-01

    Tuning the energy of an x-ray probe to an absorption line or edge can provide material-specific measurements that are particularly useful for interfaces. Simulated hard x-ray images above the Fe K-edge are presented to examine ion diffusion across an interface between Fe 2O 3 and SiO 2 aerogel foam materials. The simulations demonstrate the feasibility of such a technique for measurements of density scale lengths near the interface with submicron spatial resolution. A proof-of-principle experiment is designed and performed at the Linac coherent light source facility. Preliminary data show the change of the interface after shock compression and heating withmore » simultaneous fluorescence spectra for temperature determination. Here, the results provide the first demonstration of using x-ray imaging at an absorption edge as a diagnostic to detect ultrafast phenomena for interface physics in high-energy-density systems.« less

  3. Studies on absorption coefficient near edge of multi elements

    NASA Astrophysics Data System (ADS)

    Eisa, M. H.; Shen, H.; Yao, H. Y.; Mi, Y.; Zhou, Z. Y.; Hu, T. D.; Xie, Y. N.

    2005-12-01

    X-ray absorption near edge structure (XANES) was used to study the near edge mass-absorption coefficients of seven elements, such as, Ti, V, Fe, Co, Ni, Cu and Zn. It is well known that, on the near edge absorption of element, when incident X-ray a few eV change can make the absorption coefficient an order magnitude alteration. So that, there are only a few points mass-absorption coefficient at the near edge absorption and that always average value in published table. Our results showed a wide range of data, the total measured data of mass-absorption coefficient of the seven elements was about 505. The investigation confirmed that XANES is useful technique for multi-element absorption coefficient measurement. Details of experimental methods and results are given and discussed. The experimental work has been performed at Beijing Synchrotron Radiation Facility. The measured values were compared with the published data. Good agreement between experimental results and published data is obtained.

  4. Fundamental absorption edge of NiO nanocrystals

    NASA Astrophysics Data System (ADS)

    Sokolov, V. I.; Druzhinin, A. V.; Kim, G. A.; Gruzdev, N. B.; Yermakov, A. Ye.; Uimin, M. A.; Byzov, I. V.; Shchegoleva, N. N.; Vykhodets, V. B.; Kurennykh, T. E.

    2013-12-01

    NiO nanocrystals with the average size of 5, 10 and 25 nm were synthesized by gas-condensation method. The well-defined increase of the optical density D near the fundamental absorption edge of NiO nanocrystals in the range of 3.5-4.0 eV observed after the annealing in air is caused by the oxygen content growth. It is the direct experimental evidence of the fact that p-d charge transfer transitions form the fundamental absorption edge.

  5. Image reconstruction for x-ray K-edge imaging with a photon counting detector

    NASA Astrophysics Data System (ADS)

    Meng, Bo; Cong, Wenxiang; Xi, Yan; Wang, Ge

    2014-09-01

    Contrast agents with high-Z elements have K-absorption edges which significantly change X-ray attenuation coefficients. The K-edge characteristics is different for various kinds of contrast agents, which offers opportunities for material decomposition in biomedical applications. In this paper, we propose a new K-edge imaging method, which not only quantifies a distribution of a contrast agent but also provides an optimized contrast ratio. Our numerical simulation tests demonstrate the feasibility and merits of the proposed methodology.

  6. K-edge subtraction synchrotron X-ray imaging in bio-medical research.

    PubMed

    Thomlinson, W; Elleaume, H; Porra, L; Suortti, P

    2018-05-01

    High contrast in X-ray medical imaging, while maintaining acceptable radiation dose levels to the patient, has long been a goal. One of the most promising methods is that of K-edge subtraction imaging. This technique, first advanced as long ago as 1953 by B. Jacobson, uses the large difference in the absorption coefficient of elements at energies above and below the K-edge. Two images, one taken above the edge and one below the edge, are subtracted leaving, ideally, only the image of the distribution of the target element. This paper reviews the development of the KES techniques and technology as applied to bio-medical imaging from the early low-power tube sources of X-rays to the latest high-power synchrotron sources. Applications to coronary angiography, functional lung imaging and bone growth are highlighted. A vision of possible imaging with new compact sources is presented. Copyright © 2018 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  7. Absorption-Edge-Modulated Transmission Spectra for Water Contaminant Monitoring

    DTIC Science & Technology

    2016-03-31

    Naval Research Laboratory Washington, DC 20375-5320 NRL/MR/6390--16-9675 Absorption-Edge-Modulated Transmission Spectra for Water Contaminant ...ABSTRACT c. THIS PAGE 18. NUMBER OF PAGES 17. LIMITATION OF ABSTRACT Absorption-Edge-Modulated Transmission Spectra for Water Contaminant Monitoring...Unlimited Unclassified Unlimited 35 Samuel G. Lambrakos (202) 767-2601 Monitoring of contaminants associated with specific water resources using

  8. Virtual edge illumination and one dimensional beam tracking for absorption, refraction, and scattering retrieval

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Vittoria, Fabio A., E-mail: fabio.vittoria.12@ucl.ac.uk; Diemoz, Paul C.; Research Complex at Harwell, Harwell Oxford Campus, OX11 0FA Didcot

    2014-03-31

    We propose two different approaches to retrieve x-ray absorption, refraction, and scattering signals using a one dimensional scan and a high resolution detector. The first method can be easily implemented in existing procedures developed for edge illumination to retrieve absorption and refraction signals, giving comparable image quality while reducing exposure time and delivered dose. The second method tracks the variations of the beam intensity profile on the detector through a multi-Gaussian interpolation, allowing the additional retrieval of the scattering signal.

  9. Edge-based correlation image registration for multispectral imaging

    DOEpatents

    Nandy, Prabal [Albuquerque, NM

    2009-11-17

    Registration information for images of a common target obtained from a plurality of different spectral bands can be obtained by combining edge detection and phase correlation. The images are edge-filtered, and pairs of the edge-filtered images are then phase correlated to produce phase correlation images. The registration information can be determined based on these phase correlation images.

  10. X-ray absorption spectroscopy: EXAFS (Extended X-ray Absorption Fine Structure) and XANES (X-ray Absorption Near Edge Structure)

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Alp, E.E.; Mini, S.M.; Ramanathan, M.

    1990-04-01

    The x-ray absorption spectroscopy (XAS) had been an essential tool to gather spectroscopic information about atomic energy level structure in the early decades of this century. It has also played an important role in the discovery and systematization of rare-earth elements. The discovery of synchrotron radiation in 1952, and later the availability of broadly tunable synchrotron based x-ray sources have revitalized this technique since the 1970's. The correct interpretation of the oscillatory structure in the x-ray absorption cross-section above the absorption edge by Sayers et. al. has transformed XAS from a spectroscopic tool to a structural technique. EXAFS (Extended X-raymore » Absorption Fine Structure) yields information about the interatomic distances, near neighbor coordination numbers, and lattice dynamics. An excellent description of the principles and data analysis techniques of EXAFS is given by Teo. XANES (X-ray Absorption Near Edge Structure), on the other hand, gives information about the valence state, energy bandwidth and bond angles. Today, there are about 50 experimental stations in various synchrotrons around the world dedicated to collecting x-ray absorption data from the bulk and surfaces of solids and liquids. In this chapter, we will give the basic principles of XAS, explain the information content of essentially two different aspects of the absorption process leading to EXAFS and XANES, and discuss the source and samples limitations.« less

  11. Emission and absorption x-ray edges of Li

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Callcott, T A; Arakawa, E T; Ederer, D L

    1977-01-01

    Measurements of the K X-ray absorption and emission edges of Li are reported. They were made with the same spectrometer at the NBS storage ring and serve to establish a 0.1 eV separation between the edges with no possibility of instrument calibration error. These results are compared with recent theories of Almbladh and Mahan describing the effects of incomplete phonon relaxation about the core hole. It is concluded that these theories give a satisfactory explanation of the data.

  12. Two-Photon Absorption of Soft X-Ray Free Electron Laser Radiation by Graphite Near the Carbon K-Absorption Edge

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Christensen, Steven T; Lam, Royce K.; Raj, Sumana L.

    We have examined the transmission of soft X-ray pulses from the FERMI free electron laser through carbon films of varying thickness, quantifying nonlinear effects of pulses above and below the carbon K-edge. At typical of soft X-ray free electron laser intensities, pulses exhibit linear absorption at photon energies above and below the K-edge, ~308 and ~260 eV, respectively; whereas two-photon absorption becomes significant slightly below the K-edge, ~284.2 eV. The measured two-photon absorption cross section at 284.18 eV (~6 x 10-48 cm4 s) is 7 orders of magnitude above what is expected from a simple theory based on hydrogen-like atomsmore » - a result of resonance effects.« less

  13. Two-photon absorption of soft X-ray free electron laser radiation by graphite near the carbon K-absorption edge

    NASA Astrophysics Data System (ADS)

    Lam, Royce K.; Raj, Sumana L.; Pascal, Tod A.; Pemmaraju, C. D.; Foglia, Laura; Simoncig, Alberto; Fabris, Nicola; Miotti, Paolo; Hull, Christopher J.; Rizzuto, Anthony M.; Smith, Jacob W.; Mincigrucci, Riccardo; Masciovecchio, Claudio; Gessini, Alessandro; De Ninno, Giovanni; Diviacco, Bruno; Roussel, Eleonore; Spampinati, Simone; Penco, Giuseppe; Di Mitri, Simone; Trovò, Mauro; Danailov, Miltcho B.; Christensen, Steven T.; Sokaras, Dimosthenis; Weng, Tsu-Chien; Coreno, Marcello; Poletto, Luca; Drisdell, Walter S.; Prendergast, David; Giannessi, Luca; Principi, Emiliano; Nordlund, Dennis; Saykally, Richard J.; Schwartz, Craig P.

    2018-07-01

    We have examined the transmission of soft X-ray pulses from the FERMI free electron laser through carbon films of varying thickness, quantifying nonlinear effects of pulses above and below the carbon K-edge. At typical of soft X-ray free electron laser intensities, pulses exhibit linear absorption at photon energies above and below the K-edge, ∼308 and ∼260 eV, respectively; whereas two-photon absorption becomes significant slightly below the K-edge, ∼284.2 eV. The measured two-photon absorption cross section at 284.18 eV (∼6 × 10-48 cm4 s) is 7 orders of magnitude above what is expected from a simple theory based on hydrogen-like atoms - a result of resonance effects.

  14. Power spectrum weighted edge analysis for straight edge detection in images

    NASA Astrophysics Data System (ADS)

    Karvir, Hrishikesh V.; Skipper, Julie A.

    2007-04-01

    Most man-made objects provide characteristic straight line edges and, therefore, edge extraction is a commonly used target detection tool. However, noisy images often yield broken edges that lead to missed detections, and extraneous edges that may contribute to false target detections. We present a sliding-block approach for target detection using weighted power spectral analysis. In general, straight line edges appearing at a given frequency are represented as a peak in the Fourier domain at a radius corresponding to that frequency, and a direction corresponding to the orientation of the edges in the spatial domain. Knowing the edge width and spacing between the edges, a band-pass filter is designed to extract the Fourier peaks corresponding to the target edges and suppress image noise. These peaks are then detected by amplitude thresholding. The frequency band width and the subsequent spatial filter mask size are variable parameters to facilitate detection of target objects of different sizes under known imaging geometries. Many military objects, such as trucks, tanks and missile launchers, produce definite signatures with parallel lines and the algorithm proves to be ideal for detecting such objects. Moreover, shadow-casting objects generally provide sharp edges and are readily detected. The block operation procedure offers advantages of significant reduction in noise influence, improved edge detection, faster processing speed and versatility to detect diverse objects of different sizes in the image. With Scud missile launcher replicas as target objects, the method has been successfully tested on terrain board test images under different backgrounds, illumination and imaging geometries with cameras of differing spatial resolution and bit-depth.

  15. Edge-based image restoration.

    PubMed

    Rareş, Andrei; Reinders, Marcel J T; Biemond, Jan

    2005-10-01

    In this paper, we propose a new image inpainting algorithm that relies on explicit edge information. The edge information is used both for the reconstruction of a skeleton image structure in the missing areas, as well as for guiding the interpolation that follows. The structure reconstruction part exploits different properties of the edges, such as the colors of the objects they separate, an estimate of how well one edge continues into another one, and the spatial order of the edges with respect to each other. In order to preserve both sharp and smooth edges, the areas delimited by the recovered structure are interpolated independently, and the process is guided by the direction of the nearby edges. The novelty of our approach lies primarily in exploiting explicitly the constraint enforced by the numerical interpretation of the sequential order of edges, as well as in the pixel filling method which takes into account the proximity and direction of edges. Extensive experiments are carried out in order to validate and compare the algorithm both quantitatively and qualitatively. They show the advantages of our algorithm and its readily application to real world cases.

  16. Absorption edge parameters of the LIII edge for compounds of Hg, Tl, Pb and Bi using EDXRF technique

    NASA Astrophysics Data System (ADS)

    Singh, Gurinderjeet; Singh, Amrit; Gupta, Manoj Kumar; Dhaliwal, A. S.; Kahlon, K. S.

    2018-03-01

    The measurement of Absorption edge parameters of the LIII edge of pure elements Hg, Tl, Pb and Bi along with their compounds HgCl2, HgO, HgF2, TlCl, Tl2O3, PbCl2, PbF2, Pb3O4, BiF3, BiCl3 and Bi2O3 has been done using EDXRF technique. In the present measurements 241Am (59.54 keV) radioactive source of activity 100 mCi along with CANBERRA make cryo-cooled Si (Li) detector is used. The measured results are compared with theoretically calculated values from FFAST version 2.1 (Chantler et al., 2005) and shows good agreement with each other within experimental uncertainties within 3.5%. It is observed that the values of absorption edge parameters of the LIII edge depends slightly on the chemical environment and shows almost constant behaviour with effective atomic number (Zeff)

  17. Soft X-ray Absorption Edges in LMXBs

    NASA Technical Reports Server (NTRS)

    2004-01-01

    The XMM observation of LMC X-2 is part of our program to study X-ray absorption in the interstellar medium (ISM). This program includes a variety of bright X-ray binaries in the Galaxy as well as the Magellanic Clouds (LMC and SMC). LMC X-2 is located near the heart of the LMC. Its very soft X-ray spectrum is used to determine abundance and ionization fractions of neutral and lowly ionized oxygen of the ISM in the LMC. The RGS spectrum so far allowed us to determine the O-edge value to be for atomic O, the EW of O-I in the ls-2p resonance absorption line, and the same for O-II. The current study is still ongoing in conjunction with other low absorption sources like Sco X-1 and the recently observed X-ray binary 4U 1957+11.

  18. Active edge maps for medical image registration

    NASA Astrophysics Data System (ADS)

    Kerwin, William; Yuan, Chun

    2001-07-01

    Applying edge detection prior to performing image registration yields several advantages over raw intensity- based registration. Advantages include the ability to register multicontrast or multimodality images, immunity to intensity variations, and the potential for computationally efficient algorithms. In this work, a common framework for edge-based image registration is formulated as an adaptation of snakes used in boundary detection. Called active edge maps, the new formulation finds a one-to-one transformation T(x) that maps points in a source image to corresponding locations in a target image using an energy minimization approach. The energy consists of an image component that is small when edge features are well matched in the two images, and an internal term that restricts T(x) to allowable configurations. The active edge map formulation is illustrated here with a specific example developed for affine registration of carotid artery magnetic resonance images. In this example, edges are identified using a magnitude of gradient operator, image energy is determined using a Gaussian weighted distance function, and the internal energy includes separate, adjustable components that control volume preservation and rigidity.

  19. Enhancement of broadband optical absorption in photovoltaic devices by band-edge effect of photonic crystals.

    PubMed

    Tanaka, Yoshinori; Kawamoto, Yosuke; Fujita, Masayuki; Noda, Susumu

    2013-08-26

    We numerically investigate broadband optical absorption enhancement in thin, 400-nm thick microcrystalline silicon (µc-Si) photovoltaic devices by photonic crystals (PCs). We realize absorption enhancement by coupling the light from the free space to the large area resonant modes at the photonic band-edge induced by the photonic crystals. We show that multiple photonic band-edge modes can be produced by higher order modes in the vertical direction of the Si photovoltaic layer, which can enhance the absorption on multiple wavelengths. Moreover, we reveal that the photonic superlattice structure can produce more photonic band-edge modes that lead to further optical absorption. The absorption average in wavelengths of 500-1000 nm weighted to the solar spectrum (AM 1.5) increases almost twice: from 33% without photonic crystal to 58% with a 4 × 4 period superlattice photonic crystal; our result outperforms the Lambertian textured structure.

  20. Abnormal blueshift of the absorption edge in graphene nanodots

    NASA Astrophysics Data System (ADS)

    Sheng, Weidong

    2018-06-01

    In a conventional semiconductor, when the dielectric screening effect is suppressed, the exciton binding energy increases and the corresponding excitonic transition would exhibit a redshift in the spectrum. In this work, I study the optical properties of hexagonal graphene nanodots by using a configuration interaction approach and reveal that the edge of the absorption spectrum shows an abnormal blueshift as the environmental dielectric constant ɛr decreases. The two dominant many-body effects in the nanodot: the quasiparticle and excitonic effects are both found to scale almost linearly with ɛr-1. The former is shown to have a larger proportionality constant and thus accounts for the blueshift of the absorption edge. In contrast to the long-range Coulomb interaction, the on-site Coulomb energy is found to have a negative impact on the bright excitonic states. In the presence of a strong dielectric screening effect, a strong short-range Coulomb interaction is revealed to be responsible for the disintegration of the bright exciton.

  1. Mammographic x-ray unit kilovoltage test tool based on k-edge absorption effect.

    PubMed

    Napolitano, Mary E; Trueblood, Jon H; Hertel, Nolan E; David, George

    2002-09-01

    A simple tool to determine the peak kilovoltage (kVp) of a mammographic x-ray unit has been designed. Tool design is based on comparing the effect of k-edge discontinuity of the attenuation coefficient for a series of element filters. Compatibility with the mammography accreditation phantom (MAP) to obtain a single quality control film is a second design objective. When the attenuation of a series of sequential elements is studied simultaneously, differences in the absorption characteristics due to the k-edge discontinuities are more evident. Specifically, when the incident photon energy is higher than the k-edge energy of a number of the elements and lower than the remainder, an inflection may be seen in the resulting attenuation data. The maximum energy of the incident photon spectra may be determined based on this inflection point for a series of element filters. Monte Carlo photon transport analysis was used to estimate the photon transmission probabilities for each of the sequential k-edge filter elements. The photon transmission corresponds directly to optical density recorded on mammographic x-ray film. To observe the inflection, the element filters chosen must have k-edge energies that span a range greater than the expected range of the end point energies to be determined. For the design, incident x-ray spectra ranging from 25 to 40 kVp were assumed to be from a molybdenum target. Over this range, the k-edge energy changes by approximately 1.5 keV between sequential elements. For this design 21 elements spanning an energy range from 20 to 50 keV were chosen. Optimum filter element thicknesses were calculated to maximize attenuation differences at the k-edge while maintaining optical densities between 0.10 and 3.00. Calculated relative transmission data show that the kVp could be determined to within +/-1 kV. To obtain experimental data, a phantom was constructed containing 21 different elements placed in an acrylic holder. MAP images were used to determine

  2. X-Ray Absorption near Edge Structure Spectroscopy of Nanodiamonds from the Allende Meteorite

    NASA Technical Reports Server (NTRS)

    Flynn, G. J.; Keller, L. P.; Hill, H.; Jacobsen, C.; Wirick, S.

    2000-01-01

    Carbon X-ray Absorption Near Edge Structure Spectroscopy shows Allende DM nanodiamonds have two pre-edge peaks, consistent with other small diamonds, but fail to show a diamond exciton which is seen in 3.6 nm diamond thin films.

  3. Image segmentation on adaptive edge-preserving smoothing

    NASA Astrophysics Data System (ADS)

    He, Kun; Wang, Dan; Zheng, Xiuqing

    2016-09-01

    Nowadays, typical active contour models are widely applied in image segmentation. However, they perform badly on real images with inhomogeneous subregions. In order to overcome the drawback, this paper proposes an edge-preserving smoothing image segmentation algorithm. At first, this paper analyzes the edge-preserving smoothing conditions for image segmentation and constructs an edge-preserving smoothing model inspired by total variation. The proposed model has the ability to smooth inhomogeneous subregions and preserve edges. Then, a kind of clustering algorithm, which reasonably trades off edge-preserving and subregion-smoothing according to the local information, is employed to learn the edge-preserving parameter adaptively. At last, according to the confidence level of segmentation subregions, this paper constructs a smoothing convergence condition to avoid oversmoothing. Experiments indicate that the proposed algorithm has superior performance in precision, recall, and F-measure compared with other segmentation algorithms, and it is insensitive to noise and inhomogeneous-regions.

  4. Image Edge Extraction via Fuzzy Reasoning

    NASA Technical Reports Server (NTRS)

    Dominquez, Jesus A. (Inventor); Klinko, Steve (Inventor)

    2008-01-01

    A computer-based technique for detecting edges in gray level digital images employs fuzzy reasoning to analyze whether each pixel in an image is likely on an edge. The image is analyzed on a pixel-by-pixel basis by analyzing gradient levels of pixels in a square window surrounding the pixel being analyzed. An edge path passing through the pixel having the greatest intensity gradient is used as input to a fuzzy membership function, which employs fuzzy singletons and inference rules to assigns a new gray level value to the pixel that is related to the pixel's edginess degree.

  5. Vanadium K-edge X-ray absorption spectroscopy of bromoperoxidase from Ascophyllum nodosum

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Arber, J.M.; de Boer, E.; Garner, C.D.

    Bromoperoxidase from Ascophyllum nodusum was the first vanadium-containing enzyme to be isolated. X-ray absorption spectra have now been collected in order to investigate the coordination of vanadium in the native, native plus bromide, native plus hydrogen peroxide, and dithionite-reduced forms of the enzyme. The edge and X-ray absorption near-edge structures show that, in the four samples studied, it is only on reduction of the native enzyme that the metal site is substantially altered. In addition, these data are consistent with the presence of vanadium(IV) in the reduced enzyme and vanadium(V) in the other samples. Extended X-ray absorption fine structure datamore » confirm that there are structural changes at the metal site on reduction of the native enzyme, notably a lengthening of the average inner-shell distance, and the presence of terminal oxygen together with histidine and oxygen-donating residues.« less

  6. X-ray Absorption Spectroscopy Systematics at the Tungsten L-Edge

    PubMed Central

    2015-01-01

    A series of mononuclear six-coordinate tungsten compounds spanning formal oxidation states from 0 to +VI, largely in a ligand environment of inert chloride and/or phosphine, was interrogated by tungsten L-edge X-ray absorption spectroscopy. The L-edge spectra of this compound set, comprised of [W0(PMe3)6], [WIICl2(PMePh2)4], [WIIICl2(dppe)2][PF6] (dppe = 1,2-bis(diphenylphosphino)ethane), [WIVCl4(PMePh2)2], [WV(NPh)Cl3(PMe3)2], and [WVICl6], correlate with formal oxidation state and have usefulness as references for the interpretation of the L-edge spectra of tungsten compounds with redox-active ligands and ambiguous electronic structure descriptions. The utility of these spectra arises from the combined correlation of the estimated branching ratio of the L3,2-edges and the L1 rising-edge energy with metal Zeff, thereby permitting an assessment of effective metal oxidation state. An application of these reference spectra is illustrated by their use as backdrop for the L-edge X-ray absorption spectra of [WIV(mdt)2(CO)2] and [WIV(mdt)2(CN)2]2– (mdt2– = 1,2-dimethylethene-1,2-dithiolate), which shows that both compounds are effectively WIV species even though the mdt ligands exist at different redox levels in the two compounds. Use of metal L-edge XAS to assess a compound of uncertain formulation requires: (1) Placement of that data within the context of spectra offered by unambiguous calibrant compounds, preferably with the same coordination number and similar metal ligand distances. Such spectra assist in defining upper and/or lower limits for metal Zeff in the species of interest. (2) Evaluation of that data in conjunction with information from other physical methods, especially ligand K-edge XAS. (3) Increased care in interpretation if strong π-acceptor ligands, particularly CO, or π-donor ligands are present. The electron-withdrawing/donating nature of these ligand types, combined with relatively short metal–ligand distances, exaggerate the difference

  7. Atomic multiplets at the L2,3 edge of 3d transition metals and the ligand K edge in x-ray absorption spectroscopy of ionic systems

    NASA Astrophysics Data System (ADS)

    Olalde-Velasco, P.; Jiménez-Mier, J.; Denlinger, J.; Yang, W.-L.

    2013-06-01

    Experimental X-ray absorption spectra at the fluorine K and transition metal L2,3 absorption edges of the MF2 (M=Cr-Ni) family are presented. Ligand field calculations in D4h symmetry show very good agreement with the transition metal L2,3 XAS spectra. To successfully explain nominal Cr2+ L2,3 XAS spectrum in CrF2, the inclusion of Cr+ and Cr3+ was needed implying the presence of a disproportionation reaction. The multiplet calculations were then modified to remove the structure of the 2p hole in the calculated M 2p→3d absorption spectra. These results for the 3dn+1 states are in one to one correspondence with the leading edge structures found at the fluorine K edge. A direct comparison with the metal L2,3 edges also indicates that there is evidence of the metal multiplet at the fluorine K pre-edge structures.

  8. Identifying anthropogenic uranium compounds using soft X-ray near-edge absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Ward, Jesse D.; Bowden, Mark; Tom Resch, C.; Eiden, Gregory C.; Pemmaraju, C. D.; Prendergast, David; Duffin, Andrew M.

    2017-01-01

    Uranium ores mined for industrial use are typically acid-leached to produce yellowcake and then converted into uranium halides for enrichment and purification. These anthropogenic chemical forms of uranium are distinct from their mineral counterparts. The purpose of this study is to use soft X-ray absorption spectroscopy to characterize several common anthropogenic uranium compounds important to the nuclear fuel cycle. Chemical analyses of these compounds are important for process and environmental monitoring. X-ray absorption techniques have several advantages in this regard, including element-specificity, chemical sensitivity, and high spectral resolution. Oxygen K-edge spectra were collected for uranyl nitrate, uranyl fluoride, and uranyl chloride, and fluorine K-edge spectra were collected for uranyl fluoride and uranium tetrafluoride. Interpretation of the data is aided by comparisons to calculated spectra. The effect of hydration state on the sample, a potential complication in interpreting oxygen K-edge spectra, is discussed. These compounds have unique spectral signatures that can be used to identify unknown samples.

  9. Band-edge absorption coefficients from photoluminescence in semiconductor multiple quantum wells

    NASA Technical Reports Server (NTRS)

    Kost, Alan; Zou, Yao; Dapkus, P. D.; Garmire, Elsa; Lee, H. C.

    1989-01-01

    A novel approach to determining absorption coefficients in thin films using luminescence is described. The technique avoids many of the difficulties typically encountered in measurements of thin samples, Fabry-Perot effects, for example, and can be applied to a variety of materials. The absorption edge for GaAs/AlGaAs multiple quantum well structures, with quantum well widths ranging from 54 to 193 A is examined. Urbach (1953) parameters and excitonic linewidths are tabulated.

  10. Near-edge X-ray absorption spectra for metallic Cu and Mn

    NASA Astrophysics Data System (ADS)

    Greaves, G. N.; Durham, P. J.; Diakun, G.; Quinn, P.

    1981-11-01

    The measurement of X-ray absorption fine structure of metals- both in the extended region (EXAFS) as well as in the near edge region (XANES)-has been widely discussed (see refs 1-6 for Cu and refs 7-9 for Mn). The recent availability of intense X-ray fluxes from storage rings has usually been exploited for EXAFS leaving the XANES often with poorer resolution than earlier work performed on conventional sources (for example, compare the near edge structure for copper in ref. 1 with refs 3 or 6). In addition, whilst the theory and analysis of EXAFS is relatively well-established2,10, a theory for the strong scattering regime near to the absorption edge has only recently been developed11. We report here the first high resolution XANES spectra for Cu and Mn which were performed at the SRS storage ring at Daresbury. Although both metals have close-packed structures consisting of atoms of similar size their local atomic structure is different in detail. Significant differences are found in their respective XANES reflecting the senstivity of this region of the X-ray absorption fine structure to the local atomic structure. Spectra for the two metals have been analysed using the new multiple scattering formalism. This is a real space calculation and unlike a conventional band structure approach it does not require structural periodicity but works from the local arrangement of atoms.

  11. Edge-Based Image Compression with Homogeneous Diffusion

    NASA Astrophysics Data System (ADS)

    Mainberger, Markus; Weickert, Joachim

    It is well-known that edges contain semantically important image information. In this paper we present a lossy compression method for cartoon-like images that exploits information at image edges. These edges are extracted with the Marr-Hildreth operator followed by hysteresis thresholding. Their locations are stored in a lossless way using JBIG. Moreover, we encode the grey or colour values at both sides of each edge by applying quantisation, subsampling and PAQ coding. In the decoding step, information outside these encoded data is recovered by solving the Laplace equation, i.e. we inpaint with the steady state of a homogeneous diffusion process. Our experiments show that the suggested method outperforms the widely-used JPEG standard and can even beat the advanced JPEG2000 standard for cartoon-like images.

  12. Optical absorption edge of ZnO thin films: The effect of substrate

    NASA Astrophysics Data System (ADS)

    Srikant, V.; Clarke, D. R.

    1997-05-01

    The optical absorption edge and the near-absorption edge characteristics of undoped ZnO films grown by laser ablation on various substrates have been investigated. The band edge of films on C [(0001)] and R-plane [(1102)] sapphire, 3.29 and 3.32 eV, respectively, are found to be very close to the single crystal value of ZnO (3.3 eV) with the differences being accounted for in terms of the thermal mismatch strain using the known deformation potentials of ZnO. In contrast, films grown on fused silica consistently exhibit a band edge ˜0.1 eV lower than that predicted using the known deformation potential and the thermal mismatch strains. This behavior is attributed to the small grain size (50 nm) realized in these films and the effect of electrostatic potentials that exist at the grain boundaries. Additionally, the spread in the tail (E0) of the band edge for the different films is found to be very sensitive to the defect structure in the films. For films grown on sapphire substrates, values of E0 as low as 30 meV can be achieved on annealing in air, whereas films on fused silica always show a value >100 meV. We attribute this difference to the substantially higher density of high-angle grain boundaries in the films on fused silica.

  13. The P K-near edge absorption spectra of phosphates

    NASA Astrophysics Data System (ADS)

    Franke, R.; Hormes, J.

    1995-12-01

    The X-ray absorption near edge structure (XANES) at the P K-edge in several orthophosphates with various cations, in condensed, and in substituted sodium phosphates have been measured using synchrotron radiation from the ELSA storage ring at the University of Bonn. The measured spectra demonstrate that chemical changes beyond the PO 4- tetrahedra are reflected by energy shifts of the pre-edge and continuum resonances, by the presence of characteristic shoulders and new peaks and by differences in the intensity of the white line. We discuss the energy differences between the white line positions and the corresponding P ls binding energies as a measure of half of the energy gap. The corresponding values correlate with the valence of the cations and the intensity of the white lines. The energy positions of the continuum resonances are discussed on the basis of an empirical bond-length correlation supporting a 1/ r2 - dependence.

  14. An edge preserving differential image coding scheme

    NASA Technical Reports Server (NTRS)

    Rost, Martin C.; Sayood, Khalid

    1992-01-01

    Differential encoding techniques are fast and easy to implement. However, a major problem with the use of differential encoding for images is the rapid edge degradation encountered when using such systems. This makes differential encoding techniques of limited utility, especially when coding medical or scientific images, where edge preservation is of utmost importance. A simple, easy to implement differential image coding system with excellent edge preservation properties is presented. The coding system can be used over variable rate channels, which makes it especially attractive for use in the packet network environment.

  15. Nitrogen K-edge x-ray absorption near edge structure of pyrimidine-containing nucleotides in aqueous solution

    NASA Astrophysics Data System (ADS)

    Shimada, Hiroyuki; Minami, Hirotake; Okuizumi, Naoto; Sakuma, Ichiro; Ukai, Masatoshi; Fujii, Kentaro; Yokoya, Akinari; Fukuda, Yoshihiro; Saitoh, Yuji

    2015-05-01

    X-ray absorption near edge structure (XANES) was measured at energies around the N K-edge of the pyrimidine-containing nucleotides, cytidine 5'-monophosphate (CMP), 2'-deoxythymidine 5'-monophosphate (dTMP), and uridine 5'-monophosphate (UMP), in aqueous solutions and in dried films under various pH conditions. The features of resonant excitations below the N K-edge in the XANES spectra for CMP, dTMP, and UMP changed depending on the pH of the solutions. The spectral change thus observed is systematically explained by the chemical shift of the core-levels of N atoms in the nucleobase moieties caused by structural changes due to protonation or deprotonation at different proton concentrations. This interpretation is supported by the results of theoretical calculations using density functional theory for the corresponding nucleobases in the neutral and protonated or deprotonated forms.

  16. The influence of coordination geometry and valency on the K-edge absorption near edge spectra of selected chromium compounds

    NASA Astrophysics Data System (ADS)

    Pantelouris, A.; Modrow, H.; Pantelouris, M.; Hormes, J.; Reinen, D.

    2004-05-01

    X-ray absorption spectra at the chromium K-edge are reported for a number of selected chromium compounds of known chemical structure. The spectra were obtained with use of synchrotron radiation available at the ELectron Stretcher Accelerator ELSA in Bonn. The compounds studied include the tetrahedrally coordinated compounds Ca 2Ge 0.8Cr 0.2O 4, Ba 2Ge 0.1Cr 0.9O 4, Sr 2CrO 4, Ca 2(PO 4) x(CrO 4) 1- xCl ( x=0.25,0.5), Ca 5(CrO 4) 3Cl, CrO 3, the octahedrally coordinated compounds Cr(II)-acetate, CrCl 3, CrF 3, Cr 2O 3, KCr(SO 4) 2 · 12H 2O, CrO 2 and cubic coordinated metallic chromium. In these compounds chromium exhibits a wide range of formal oxidation states (0 to VI). The absorption features in the near edge region are shown to be characteristic of the spatial environment of the absorbing atom. The occurrence of a single pre-edge line easily allows one to distinguish between tetrahedral and octahedral coordination geometry, whereas the energy position of the absorption edge is found to be very sensitive to the valency of the excited chromium atom. Calculations of the ionisation potential of Cr in different oxidation states using the non-relativistic Hartree-Fock method (Froese-Fischer) confirm that the ionisation limit shifts to higher energy with increasing Cr valency. More detailed information on the electronic structure of the different compounds is gained by real-space full multiple scattering calculations using the FEFF8 code.

  17. Single shot near edge x-ray absorption fine structure spectroscopy in the laboratory

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Mantouvalou, I., E-mail: ioanna.mantouvalou@tu-berlin.de; Witte, K.; Martyanov, W.

    With the help of adapted off-axis reflection zone plates, near edge X-ray absorption fine structure spectra at the C and N K-absorption edge have been recorded using a single 1.2 ns long soft X-ray pulse. The transmission experiments were performed with a laser-produced plasma source in the laboratory rendering time resolved measurements feasible independent on large scale facilities. A resolving power of E/ΔE ∼ 950 at the respective edges could be demonstrated. A comparison of single shot spectra with those collected with longer measuring time proves that all features of the used reference samples (silicon nitrate and polyimide) can be resolved in 1.2 ns.more » Hence, investigations of radiation sensitive biological specimen become possible due to the high efficiency of the optical elements enabling low dose experiments.« less

  18. X-ray absorption spectroscopy systematics at the tungsten L-edge.

    PubMed

    Jayarathne, Upul; Chandrasekaran, Perumalreddy; Greene, Angelique F; Mague, Joel T; DeBeer, Serena; Lancaster, Kyle M; Sproules, Stephen; Donahue, James P

    2014-08-18

    A series of mononuclear six-coordinate tungsten compounds spanning formal oxidation states from 0 to +VI, largely in a ligand environment of inert chloride and/or phosphine, was interrogated by tungsten L-edge X-ray absorption spectroscopy. The L-edge spectra of this compound set, comprised of [W(0)(PMe3)6], [W(II)Cl2(PMePh2)4], [W(III)Cl2(dppe)2][PF6] (dppe = 1,2-bis(diphenylphosphino)ethane), [W(IV)Cl4(PMePh2)2], [W(V)(NPh)Cl3(PMe3)2], and [W(VI)Cl6], correlate with formal oxidation state and have usefulness as references for the interpretation of the L-edge spectra of tungsten compounds with redox-active ligands and ambiguous electronic structure descriptions. The utility of these spectra arises from the combined correlation of the estimated branching ratio of the L3,2-edges and the L1 rising-edge energy with metal Zeff, thereby permitting an assessment of effective metal oxidation state. An application of these reference spectra is illustrated by their use as backdrop for the L-edge X-ray absorption spectra of [W(IV)(mdt)2(CO)2] and [W(IV)(mdt)2(CN)2](2-) (mdt(2-) = 1,2-dimethylethene-1,2-dithiolate), which shows that both compounds are effectively W(IV) species even though the mdt ligands exist at different redox levels in the two compounds. Use of metal L-edge XAS to assess a compound of uncertain formulation requires: (1) Placement of that data within the context of spectra offered by unambiguous calibrant compounds, preferably with the same coordination number and similar metal ligand distances. Such spectra assist in defining upper and/or lower limits for metal Zeff in the species of interest. (2) Evaluation of that data in conjunction with information from other physical methods, especially ligand K-edge XAS. (3) Increased care in interpretation if strong π-acceptor ligands, particularly CO, or π-donor ligands are present. The electron-withdrawing/donating nature of these ligand types, combined with relatively short metal-ligand distances, exaggerate

  19. X-ray absorption near-edge spectroscopy in bioinorganic chemistry: Application to M–O2 systems

    PubMed Central

    Sarangi, Ritimukta

    2012-01-01

    Metal K-edge X-ray absorption spectroscopy (XAS) has been extensively applied to bioinorganic chemistry to obtain geometric structure information on metalloprotein and biomimetic model complex active sites by analyzing the higher energy extended X-ray absorption fine structure (EXAFS) region of the spectrum. In recent years, focus has been on developing methodologies to interpret the lower energy K-pre-edge and rising-edge regions (XANES) and using it for electronic structure determination in complex bioinorganic systems. In this review, the evolution and progress of 3d-transition metal K-pre-edge and rising-edge methodology development is presented with particular focus on applications to bioinorganic systems. Applications to biomimetic transition metal–O2 intermediates (M = Fe, Co, Ni and Cu) are reviewed, which demonstrate the power of the method as an electronic structure determination technique and its impact in understanding the role of supporting ligands in tuning the electronic configuration of transition metal–O2 systems. PMID:23525635

  20. Identification of Uranyl Minerals Using Oxygen K-Edge X Ray Absorption Spectroscopy

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ward, Jesse D.; Bowden, Mark E.; Resch, Charles T.

    2016-03-01

    Uranium analysis is consistently needed throughout the fuel cycle, from mining to fuel fabrication to environmental monitoring. Although most of the world’s uranium is immobilized as pitchblende or uraninite, there exists a plethora of secondary uranium minerals, nearly all of which contain the uranyl cation. Analysis of uranyl compounds can provide clues as to a sample’s facility of origin and chemical history. X-ray absorption spectroscopy is one technique that could enhance our ability to identify uranium minerals. Although there is limited chemical information to be gained from the uranium X-ray absorption edges, recent studies have successfully used ligand NEXAFS tomore » study the physical chemistry of various uranium compounds. This study extends the use of ligand NEXAFS to analyze a suite of uranium minerals. We find that major classes of uranyl compounds (carbonate, oxyhydroxide, silicate, and phosphate) exhibit characteristic lineshapes in the oxygen K-edge absorption spectra. As a result, this work establishes a library of reference spectra that can be used to classify unknown uranyl minerals.« less

  1. Nitrogen K-edge x-ray absorption near edge structure of pyrimidine-containing nucleotides in aqueous solution

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Shimada, Hiroyuki, E-mail: hshimada@cc.tuat.ac.jp; Minami, Hirotake; Okuizumi, Naoto

    2015-05-07

    X-ray absorption near edge structure (XANES) was measured at energies around the N K-edge of the pyrimidine-containing nucleotides, cytidine 5′-monophosphate (CMP), 2′-deoxythymidine 5′-monophosphate (dTMP), and uridine 5′-monophosphate (UMP), in aqueous solutions and in dried films under various pH conditions. The features of resonant excitations below the N K-edge in the XANES spectra for CMP, dTMP, and UMP changed depending on the pH of the solutions. The spectral change thus observed is systematically explained by the chemical shift of the core-levels of N atoms in the nucleobase moieties caused by structural changes due to protonation or deprotonation at different proton concentrations.more » This interpretation is supported by the results of theoretical calculations using density functional theory for the corresponding nucleobases in the neutral and protonated or deprotonated forms.« less

  2. Reducing radiation dose by application of optimized low-energy x-ray filters to K-edge imaging with a photon counting detector.

    PubMed

    Choi, Yu-Na; Lee, Seungwan; Kim, Hee-Joung

    2016-01-21

    K-edge imaging with photon counting x-ray detectors (PCXDs) can improve image quality compared with conventional energy integrating detectors. However, low-energy x-ray photons below the K-edge absorption energy of a target material do not contribute to image formation in the K-edge imaging and are likely to be completely absorbed by an object. In this study, we applied x-ray filters to the K-edge imaging with a PCXD based on cadmium zinc telluride for reducing radiation dose induced by low-energy x-ray photons. We used aluminum (Al) filters with different thicknesses as the low-energy x-ray filters and implemented the iodine K-edge imaging with an energy bin of 34-48 keV at the tube voltages of 50, 70 and 90 kVp. The effects of the low-energy x-ray filters on the K-edge imaging were investigated with respect to signal-difference-to-noise ratio (SDNR), entrance surface air kerma (ESAK) and figure of merit (FOM). The highest value of SDNR was observed in the K-edge imaging with a 2 mm Al filter, and the SDNR decreased as a function of the filter thicknesses. Compared to the K-edge imaging with a 2 mm Al filter, the ESAK was reduced by 66%, 48% and 39% in the K-edge imaging with a 12 mm Al filter for 50 kVp, 70 kVp and 90 kVp, respectively. The FOM values, which took into account the ESAK and SDNR, were maximized for 8, 6 to 8 and 4 mm Al filters at 50 kVp, 70 kVp and 90 kVp, respectively. We concluded that the use of an optimal low-energy filter thickness, which was determined by maximizing the FOM, could significantly reduce radiation dose while maintaining image quality in the K-edge imaging with the PCXD.

  3. Canny edge-based deformable image registration

    NASA Astrophysics Data System (ADS)

    Kearney, Vasant; Huang, Yihui; Mao, Weihua; Yuan, Baohong; Tang, Liping

    2017-02-01

    This work focuses on developing a 2D Canny edge-based deformable image registration (Canny DIR) algorithm to register in vivo white light images taken at various time points. This method uses a sparse interpolation deformation algorithm to sparsely register regions of the image with strong edge information. A stability criterion is enforced which removes regions of edges that do not deform in a smooth uniform manner. Using a synthetic mouse surface ground truth model, the accuracy of the Canny DIR algorithm was evaluated under axial rotation in the presence of deformation. The accuracy was also tested using fluorescent dye injections, which were then used for gamma analysis to establish a second ground truth. The results indicate that the Canny DIR algorithm performs better than rigid registration, intensity corrected Demons, and distinctive features for all evaluation matrices and ground truth scenarios. In conclusion Canny DIR performs well in the presence of the unique lighting and shading variations associated with white-light-based image registration.

  4. Markov random field model-based edge-directed image interpolation.

    PubMed

    Li, Min; Nguyen, Truong Q

    2008-07-01

    This paper presents an edge-directed image interpolation algorithm. In the proposed algorithm, the edge directions are implicitly estimated with a statistical-based approach. In opposite to explicit edge directions, the local edge directions are indicated by length-16 weighting vectors. Implicitly, the weighting vectors are used to formulate geometric regularity (GR) constraint (smoothness along edges and sharpness across edges) and the GR constraint is imposed on the interpolated image through the Markov random field (MRF) model. Furthermore, under the maximum a posteriori-MRF framework, the desired interpolated image corresponds to the minimal energy state of a 2-D random field given the low-resolution image. Simulated annealing methods are used to search for the minimal energy state from the state space. To lower the computational complexity of MRF, a single-pass implementation is designed, which performs nearly as well as the iterative optimization. Simulation results show that the proposed MRF model-based edge-directed interpolation method produces edges with strong geometric regularity. Compared to traditional methods and other edge-directed interpolation methods, the proposed method improves the subjective quality of the interpolated edges while maintaining a high PSNR level.

  5. Assignment of Pre-edge Features in the Ru K-edge X-ray Absorption Spectra of Organometallic Ruthenium Complexes

    PubMed Central

    Getty, Kendra; Delgado-Jaime, Mario Ulises

    2010-01-01

    The nature of the lowest energy bound-state transition in the Ru K-edge X-ray Absorption Spectra for a series of Grubbs-type ruthenium complexes was investigated. The pre-edge feature was unambiguously assigned as resulting from formally electric dipole forbidden Ru 4d←1s transitions. The intensities of these transitions are extremely sensitive to the ligand environment and the symmetry of the metal centre. In centrosymmetric complexes the pre-edge is very weak since it is limited by the weak electric quadrupole intensity mechanism. By contrast, upon breaking centrosymmetry, Ru 5p-4d mixing allows for introduction of electric dipole allowed character resulting in a dramatic increase in the pre-edge intensity. The information content of this approach is explored as it relates to complexes of importance in olefin metathesis and its relevance as a tool for the study of reactive intermediates. PMID:20151030

  6. Edge directed image interpolation with Bamberger pyramids

    NASA Astrophysics Data System (ADS)

    Rosiles, Jose Gerardo

    2005-08-01

    Image interpolation is a standard feature in digital image editing software, digital camera systems and printers. Classical methods for resizing produce blurred images with unacceptable quality. Bamberger Pyramids and filter banks have been successfully used for texture and image analysis. They provide excellent multiresolution and directional selectivity. In this paper we present an edge-directed image interpolation algorithm which takes advantage of the simultaneous spatial-directional edge localization at the subband level. The proposed algorithm outperform classical schemes like bilinear and bicubic schemes from the visual and numerical point of views.

  7. Edge physics of the quantum spin Hall insulator from a quantum dot excited by optical absorption.

    PubMed

    Vasseur, Romain; Moore, Joel E

    2014-04-11

    The gapless edge modes of the quantum spin Hall insulator form a helical liquid in which the direction of motion along the edge is determined by the spin orientation of the electrons. In order to probe the Luttinger liquid physics of these edge states and their interaction with a magnetic (Kondo) impurity, we consider a setup where the helical liquid is tunnel coupled to a semiconductor quantum dot that is excited by optical absorption, thereby inducing an effective quantum quench of the tunneling. At low energy, the absorption spectrum is dominated by a power-law singularity. The corresponding exponent is directly related to the interaction strength (Luttinger parameter) and can be computed exactly using boundary conformal field theory thanks to the unique nature of the quantum spin Hall edge.

  8. An edge-directed interpolation method for fetal spine MR images.

    PubMed

    Yu, Shaode; Zhang, Rui; Wu, Shibin; Hu, Jiani; Xie, Yaoqin

    2013-10-10

    Fetal spinal magnetic resonance imaging (MRI) is a prenatal routine for proper assessment of fetus development, especially when suspected spinal malformations occur while ultrasound fails to provide details. Limited by hardware, fetal spine MR images suffer from its low resolution.High-resolution MR images can directly enhance readability and improve diagnosis accuracy. Image interpolation for higher resolution is required in clinical situations, while many methods fail to preserve edge structures. Edge carries heavy structural messages of objects in visual scenes for doctors to detect suspicions, classify malformations and make correct diagnosis. Effective interpolation with well-preserved edge structures is still challenging. In this paper, we propose an edge-directed interpolation (EDI) method and apply it on a group of fetal spine MR images to evaluate its feasibility and performance. This method takes edge messages from Canny edge detector to guide further pixel modification. First, low-resolution (LR) images of fetal spine are interpolated into high-resolution (HR) images with targeted factor by bi-linear method. Then edge information from LR and HR images is put into a twofold strategy to sharpen or soften edge structures. Finally a HR image with well-preserved edge structures is generated. The HR images obtained from proposed method are validated and compared with that from other four EDI methods. Performances are evaluated from six metrics, and subjective analysis of visual quality is based on regions of interest (ROI). All these five EDI methods are able to generate HR images with enriched details. From quantitative analysis of six metrics, the proposed method outperforms the other four from signal-to-noise ratio (SNR), peak signal-to-noise ratio (PSNR), structure similarity index (SSIM), feature similarity index (FSIM) and mutual information (MI) with seconds-level time consumptions (TC). Visual analysis of ROI shows that the proposed method maintains

  9. The Edge Detectors Suitable for Retinal OCT Image Segmentation

    PubMed Central

    Yang, Jing; Gao, Qian; Zhou, Sheng

    2017-01-01

    Retinal layer thickness measurement offers important information for reliable diagnosis of retinal diseases and for the evaluation of disease development and medical treatment responses. This task critically depends on the accurate edge detection of the retinal layers in OCT images. Here, we intended to search for the most suitable edge detectors for the retinal OCT image segmentation task. The three most promising edge detection algorithms were identified in the related literature: Canny edge detector, the two-pass method, and the EdgeFlow technique. The quantitative evaluation results show that the two-pass method outperforms consistently the Canny detector and the EdgeFlow technique in delineating the retinal layer boundaries in the OCT images. In addition, the mean localization deviation metrics show that the two-pass method caused the smallest edge shifting problem. These findings suggest that the two-pass method is the best among the three algorithms for detecting retinal layer boundaries. The overall better performance of Canny and two-pass methods over EdgeFlow technique implies that the OCT images contain more intensity gradient information than texture changes along the retinal layer boundaries. The results will guide our future efforts in the quantitative analysis of retinal OCT images for the effective use of OCT technologies in the field of ophthalmology. PMID:29065594

  10. Absorption and scattering by interstellar dust in the silicon K-edge of GX 5-1

    NASA Astrophysics Data System (ADS)

    Zeegers, S. T.; Costantini, E.; de Vries, C. P.; Tielens, A. G. G. M.; Chihara, H.; de Groot, F.; Mutschke, H.; Waters, L. B. F. M.; Zeidler, S.

    2017-03-01

    Context. We study the absorption and scattering of X-ray radiation by interstellar dust particles, which allows us to access the physical and chemical properties of dust. The interstellar dust composition is not well understood, especially on the densest sight lines of the Galactic plane. X-rays provide a powerful tool in this study. Aims: We present newly acquired laboratory measurements of silicate compounds taken at the Soleil synchrotron facility in Paris using the Lucia beamline. The dust absorption profiles resulting from this campaign were used in this pilot study to model the absorption by interstellar dust along the line of sight of the low-mass X-ray binary GX 5-1. Methods: The measured laboratory cross-sections were adapted for astrophysical data analysis and the resulting extinction profiles of the Si K-edge were implemented in the SPEX spectral fitting program. We derive the properties of the interstellar dust along the line of sight by fitting the Si K-edge seen in absorption in the spectrum of GX 5-1. Results: We measured the hydrogen column density towards GX 5-1 to be 3.40 ± 0.1 × 1022 cm-2. The best fit of the silicon edge in the spectrum of GX 5-1 is obtained by a mixture of olivine and pyroxene. In this study, our modeling is limited to Si absorption by silicates with different Mg:Fe ratios. We obtained an abundance of silicon in dust of 4.0 ± 0.3 × 10-5 per H atom and a lower limit for total abundance, considering both gas and dust of >4.4 × 10-5 per H atom, which leads to a gas to dust ratio of >0.22. Furthermore, an enhanced scattering feature in the Si K-edge may suggest the presence of large particles along the line of sight.

  11. Edge Sharpness Assessment by Parametric Modeling: Application to Magnetic Resonance Imaging.

    PubMed

    Ahmad, R; Ding, Y; Simonetti, O P

    2015-05-01

    In biomedical imaging, edge sharpness is an important yet often overlooked image quality metric. In this work, a semi-automatic method to quantify edge sharpness in the presence of significant noise is presented with application to magnetic resonance imaging (MRI). The method is based on parametric modeling of image edges. First, an edge map is automatically generated and one or more edges-of-interest (EOI) are manually selected using graphical user interface. Multiple exclusion criteria are then enforced to eliminate edge pixels that are potentially not suitable for sharpness assessment. Second, at each pixel of the EOI, an image intensity profile is read along a small line segment that runs locally normal to the EOI. Third, the profiles corresponding to all EOI pixels are individually fitted with a sigmoid function characterized by four parameters, including one that represents edge sharpness. Last, the distribution of the sharpness parameter is used to quantify edge sharpness. For validation, the method is applied to simulated data as well as MRI data from both phantom imaging and cine imaging experiments. This method allows for fast, quantitative evaluation of edge sharpness even in images with poor signal-to-noise ratio. Although the utility of this method is demonstrated for MRI, it can be adapted for other medical imaging applications.

  12. Efficient method of image edge detection based on FSVM

    NASA Astrophysics Data System (ADS)

    Cai, Aiping; Xiong, Xiaomei

    2013-07-01

    For efficient object cover edge detection in digital images, this paper studied traditional methods and algorithm based on SVM. It analyzed Canny edge detection algorithm existed some pseudo-edge and poor anti-noise capability. In order to provide a reliable edge extraction method, propose a new detection algorithm based on FSVM. Which contains several steps: first, trains classify sample and gives the different membership function to different samples. Then, a new training sample is formed by increase the punishment some wrong sub-sample, and use the new FSVM classification model for train and test them. Finally the edges are extracted of the object image by using the model. Experimental result shows that good edge detection image will be obtained and adding noise experiments results show that this method has good anti-noise.

  13. Edge-illumination x-ray phase contrast imaging with Pt-based metallic glass masks

    NASA Astrophysics Data System (ADS)

    Saghamanesh, Somayeh; Aghamiri, Seyed Mahmoud-Reza; Olivo, Alessandro; Sadeghilarijani, Maryam; Kato, Hidemi; Kamali-Asl, Alireza; Yashiro, Wataru

    2017-06-01

    Edge-illumination x-ray phase contrast imaging (EI XPCI) is a non-interferometric phase-sensitive method where two absorption masks are employed. These masks are fabricated through a photolithography process followed by electroplating which is challenging in terms of yield as well as time- and cost-effectiveness. We report on the first implementation of EI XPCI with Pt-based metallic glass masks fabricated by an imprinting method. The new tested alloy exhibits good characteristics including high workability beside high x-ray attenuation. The fabrication process is easy and cheap, and can produce large-size masks for high x-ray energies within minutes. Imaging experiments show a good quality phase image, which confirms the potential of these masks to make the EI XPCI technique widely available and affordable.

  14. Edge enhancement algorithm for low-dose X-ray fluoroscopic imaging.

    PubMed

    Lee, Min Seok; Park, Chul Hee; Kang, Moon Gi

    2017-12-01

    Low-dose X-ray fluoroscopy has continually evolved to reduce radiation risk to patients during clinical diagnosis and surgery. However, the reduction in dose exposure causes quality degradation of the acquired images. In general, an X-ray device has a time-average pre-processor to remove the generated quantum noise. However, this pre-processor causes blurring and artifacts within the moving edge regions, and noise remains in the image. During high-pass filtering (HPF) to enhance edge detail, this noise in the image is amplified. In this study, a 2D edge enhancement algorithm comprising region adaptive HPF with the transient improvement (TI) method, as well as artifacts and noise reduction (ANR), was developed for degraded X-ray fluoroscopic images. The proposed method was applied in a static scene pre-processed by a low-dose X-ray fluoroscopy device. First, the sharpness of the X-ray image was improved using region adaptive HPF with the TI method, which facilitates sharpening of edge details without overshoot problems. Then, an ANR filter that uses an edge directional kernel was developed to remove the artifacts and noise that can occur during sharpening, while preserving edge details. The quantitative and qualitative results obtained by applying the developed method to low-dose X-ray fluoroscopic images and visually and numerically comparing the final images with images improved using conventional edge enhancement techniques indicate that the proposed method outperforms existing edge enhancement methods in terms of objective criteria and subjective visual perception of the actual X-ray fluoroscopic image. The developed edge enhancement algorithm performed well when applied to actual low-dose X-ray fluoroscopic images, not only by improving the sharpness, but also by removing artifacts and noise, including overshoot. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Swarm Intelligence for Optimizing Hybridized Smoothing Filter in Image Edge Enhancement

    NASA Astrophysics Data System (ADS)

    Rao, B. Tirumala; Dehuri, S.; Dileep, M.; Vindhya, A.

    In this modern era, image transmission and processing plays a major role. It would be impossible to retrieve information from satellite and medical images without the help of image processing techniques. Edge enhancement is an image processing step that enhances the edge contrast of an image or video in an attempt to improve its acutance. Edges are the representations of the discontinuities of image intensity functions. For processing these discontinuities in an image, a good edge enhancement technique is essential. The proposed work uses a new idea for edge enhancement using hybridized smoothening filters and we introduce a promising technique of obtaining best hybrid filter using swarm algorithms (Artificial Bee Colony (ABC), Particle Swarm Optimization (PSO) and Ant Colony Optimization (ACO)) to search for an optimal sequence of filters from among a set of rather simple, representative image processing filters. This paper deals with the analysis of the swarm intelligence techniques through the combination of hybrid filters generated by these algorithms for image edge enhancement.

  16. Identifying anthropogenic uranium compounds using soft X-ray near-edge absorption spectroscopy

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ward, Jesse D.; Bowden, Mark; Tom Resch, C.

    2017-01-01

    Uranium ores mined for industrial use are typically acid-leached to produce yellowcake and then converted into uranium halides for enrichment and purification. These anthropogenic chemical forms of uranium are distinct from their mineral counterparts. The purpose of this study is to use soft X-ray absorption spectroscopy to characterize several common anthropogenic uranium compounds important to the nuclear fuel cycle. Non-destructive chemical analyses of these compounds is important for process and environmental monitoring and X-ray absorption techniques have several advantages in this regard, including element-specificity, chemical sensitivity, and high spectral resolution. Oxygen K-edge spectra were collected for uranyl nitrate, uranyl fluoride,more » and uranyl chloride, and fluorine K-edge spectra were collected for uranyl fluoride and uranium tetrafluoride. Interpretation of the data is aided by comparisons to calculated spectra. These compounds have unique spectral signatures that can be used to identify unknown samples.« less

  17. Nonlinear refraction at the absorption edge in InAs.

    PubMed

    Poole, C D; Garmire, E

    1984-08-01

    The results of measurements of nonlinear refraction at the absorption edge in InAs between 68 and 90 K taken with an HF laser are compared with those of a band-gap resonant model in which the contribution of the light-hole band is included and found to account for more than 40% of the observed nonlinear refraction. A generalized expression for the nonlinear index is derived by using the complete Fermi-Dirac distribution function. Good agreement between theory and experiment is obtained, with no free parameters.

  18. Approximating the near-edge mass absorption coefficients for Ni using an ultra-thin bimetal foil

    DOE PAGES

    Alkire, Randall W.

    2016-11-01

    In an effort to improve the characteristics of a fluorescing metal-foil-based beam position monitor, a new bimetal ultra-thin (0.98/0.67 µm) Ti–Ni foil was introduced to replace an existing single-element ultra-thin 0.5 µm thick Cr foil. During characterization it was determined that absorption measurements on the bimetal foil could be used to fit the Ni mass absorption coefficients accurately in the vicinity of the NiKedge. Comparison with experimental results from the literature demonstrated that the fitting procedure produced coefficients with uncertainties of the order of ±1%. Once determined, these fit coefficients allowed the thickness of an independently mounted 8 µm thickmore » Ni foil to be computed from absorption measurements instead of relying on a tool-based measurement of the foil thickness. Using the 8 µm thick foil, a continuous map of Ni mass absorption coefficients was produced at 1 eV resolution throughout the near-edge region. Lastly, this high-resolution map marks a significant improvement over the existing NIST XCOM or FFAST database mass absorption coefficients, which have estimated errors of 10–20% for the near-edge region.« less

  19. Method for wafer edge profile extraction using optical images obtained in edge defect inspection process

    NASA Astrophysics Data System (ADS)

    Okamoto, Hiroaki; Sakaguchi, Naoshi; Hayano, Fuminori

    2010-03-01

    It is becoming increasingly important to monitor wafer edge profiles in the immersion lithography era. A Nikon edge defect inspection tool acquires the circumferential optical images of the wafer edge during its inspection process. Nikon's unique illumination system and optics make it possible to then convert the brightness data of the captured images to quantifiable edge profile information. During this process the wafer's outer shape is also calculated. Test results show that even newly shipped bare wafers may not have a constant shape over 360 degree. In some cases repeated deformations with 90 degree pitch are observed.

  20. Edge-oriented dual-dictionary guided enrichment (EDGE) for MRI-CT image reconstruction.

    PubMed

    Li, Liang; Wang, Bigong; Wang, Ge

    2016-01-01

    In this paper, we formulate the joint/simultaneous X-ray CT and MRI image reconstruction. In particular, a novel algorithm is proposed for MRI image reconstruction from highly under-sampled MRI data and CT images. It consists of two steps. First, a training dataset is generated from a series of well-registered MRI and CT images on the same patients. Then, an initial MRI image of a patient can be reconstructed via edge-oriented dual-dictionary guided enrichment (EDGE) based on the training dataset and a CT image of the patient. Second, an MRI image is reconstructed using the dictionary learning (DL) algorithm from highly under-sampled k-space data and the initial MRI image. Our algorithm can establish a one-to-one correspondence between the two imaging modalities, and obtain a good initial MRI estimation. Both noise-free and noisy simulation studies were performed to evaluate and validate the proposed algorithm. The results with different under-sampling factors show that the proposed algorithm performed significantly better than those reconstructed using the DL algorithm from MRI data alone.

  1. Image edge detection based tool condition monitoring with morphological component analysis.

    PubMed

    Yu, Xiaolong; Lin, Xin; Dai, Yiquan; Zhu, Kunpeng

    2017-07-01

    The measurement and monitoring of tool condition are keys to the product precision in the automated manufacturing. To meet the need, this study proposes a novel tool wear monitoring approach based on the monitored image edge detection. Image edge detection has been a fundamental tool to obtain features of images. This approach extracts the tool edge with morphological component analysis. Through the decomposition of original tool wear image, the approach reduces the influence of texture and noise for edge measurement. Based on the target image sparse representation and edge detection, the approach could accurately extract the tool wear edge with continuous and complete contour, and is convenient in charactering tool conditions. Compared to the celebrated algorithms developed in the literature, this approach improves the integrity and connectivity of edges, and the results have shown that it achieves better geometry accuracy and lower error rate in the estimation of tool conditions. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

  2. First Order Statistics of Speckle around a Scatterer Volume Density Edge and Edge Detection in Ultrasound Images.

    NASA Astrophysics Data System (ADS)

    Li, Yue

    1990-01-01

    Ultrasonic imaging plays an important role in medical imaging. But the images exhibit a granular structure, commonly known as speckle. The speckle tends to mask the presence of low-contrast lesions and reduces the ability of a human observer to resolve fine details. Our interest in this research is to examine the problem of edge detection and come up with methods for improving the visualization of organ boundaries and tissue inhomogeneity edges. An edge in an image can be formed either by acoustic impedance change or by scatterer volume density change (or both). The echo produced from these two kinds of edges has different properties. In this work, it has been proved that the echo from a scatterer volume density edge is the Hilbert transform of the echo from a rough impedance boundary (except for a constant) under certain conditions. This result can be used for choosing the correct signal to transmit to optimize the performance of edge detectors and characterizing an edge. The signal to noise ratio of the echo produced by a scatterer volume density edge is also obtained. It is found that: (1) By transmitting a signal with high bandwidth ratio and low center frequency, one can obtain a higher signal to noise ratio. (2) For large area edges, the farther the transducer is from the edge, the larger is the signal to noise ratio. But for small area edges, the nearer the transducer is to the edge, the larger is the signal to noise ratio. These results enable us to maximize the signal to noise ratio by adjusting these parameters. (3) The signal to noise ratio is not only related to the ratio of scatterer volume densities at the edge, but also related to the absolute value of scatterer volume densities. Some of these results have been proved through simulation and experiment. Different edge detection methods have been used to detect simulated scatterer volume density edges to compare their performance. A so-called interlaced array method has been developed for speckle

  3. Automatic comic page image understanding based on edge segment analysis

    NASA Astrophysics Data System (ADS)

    Liu, Dong; Wang, Yongtao; Tang, Zhi; Li, Luyuan; Gao, Liangcai

    2013-12-01

    Comic page image understanding aims to analyse the layout of the comic page images by detecting the storyboards and identifying the reading order automatically. It is the key technique to produce the digital comic documents suitable for reading on mobile devices. In this paper, we propose a novel comic page image understanding method based on edge segment analysis. First, we propose an efficient edge point chaining method to extract Canny edge segments (i.e., contiguous chains of Canny edge points) from the input comic page image; second, we propose a top-down scheme to detect line segments within each obtained edge segment; third, we develop a novel method to detect the storyboards by selecting the border lines and further identify the reading order of these storyboards. The proposed method is performed on a data set consisting of 2000 comic page images from ten printed comic series. The experimental results demonstrate that the proposed method achieves satisfactory results on different comics and outperforms the existing methods.

  4. Edge Detection Method Based on Neural Networks for COMS MI Images

    NASA Astrophysics Data System (ADS)

    Lee, Jin-Ho; Park, Eun-Bin; Woo, Sun-Hee

    2016-12-01

    Communication, Ocean And Meteorological Satellite (COMS) Meteorological Imager (MI) images are processed for radiometric and geometric correction from raw image data. When intermediate image data are matched and compared with reference landmark images in the geometrical correction process, various techniques for edge detection can be applied. It is essential to have a precise and correct edged image in this process, since its matching with the reference is directly related to the accuracy of the ground station output images. An edge detection method based on neural networks is applied for the ground processing of MI images for obtaining sharp edges in the correct positions. The simulation results are analyzed and characterized by comparing them with the results of conventional methods, such as Sobel and Canny filters.

  5. Comparison of morphological and conventional edge detectors in medical imaging applications

    NASA Astrophysics Data System (ADS)

    Kaabi, Lotfi; Loloyan, Mansur; Huang, H. K.

    1991-06-01

    Recently, mathematical morphology has been used to develop efficient image analysis tools. This paper compares the performance of morphological and conventional edge detectors applied to radiological images. Two morphological edge detectors including the dilation residue found by subtracting the original signal from its dilation by a small structuring element, and the blur-minimization edge detector which is defined as the minimum of erosion and dilation residues of the blurred image version, are compared with the linear Laplacian and Sobel and the non-linear Robert edge detectors. Various structuring elements were used in this study: regular 2-dimensional, and 3-dimensional. We utilized two criterions for edge detector's performance classification: edge point connectivity and the sensitivity to the noise. CT/MR and chest radiograph images have been used as test data. Comparison results show that the blur-minimization edge detector, with a rolling ball-like structuring element outperforms other standard linear and nonlinear edge detectors. It is less noise sensitive, and performs the most closed contours.

  6. Absorption Mode FT-ICR Mass Spectrometry Imaging

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Smith, Donald F.; Kilgour, David P.; Konijnenburg, Marco

    2013-12-03

    Fourier transform ion cyclotron resonance mass spectrometry offers the highest mass resolving power for molecular imaging experiments. This high mass resolving power ensures that closely spaced peaks at the same nominal mass are resolved for proper image generation. Typically higher magnetic fields are used to increase mass resolving power. However, a gain in mass resolving power can also be realized by phase correction of the data for absorption mode display. In addition to mass resolving power, absorption mode offers higher mass accuracy and signal-to-noise ratio over the conventional magnitude mode. Here we present the first use of absorption mode formore » Fourier transform ion cyclotron resonance mass spectrometry imaging. The Autophaser algorithm is used to phase correct each spectrum (pixel) in the image and then these parameters are used by the Chameleon work-flow based data processing software to generate absorption mode ?Datacubes? for image and spectral viewing. Absorption mode reveals new mass and spatial features that are not resolved in magnitude mode and results in improved selected ion image contrast.« less

  7. Comparing object recognition from binary and bipolar edge images for visual prostheses.

    PubMed

    Jung, Jae-Hyun; Pu, Tian; Peli, Eli

    2016-11-01

    Visual prostheses require an effective representation method due to the limited display condition which has only 2 or 3 levels of grayscale in low resolution. Edges derived from abrupt luminance changes in images carry essential information for object recognition. Typical binary (black and white) edge images have been used to represent features to convey essential information. However, in scenes with a complex cluttered background, the recognition rate of the binary edge images by human observers is limited and additional information is required. The polarity of edges and cusps (black or white features on a gray background) carries important additional information; the polarity may provide shape from shading information missing in the binary edge image. This depth information may be restored by using bipolar edges. We compared object recognition rates from 16 binary edge images and bipolar edge images by 26 subjects to determine the possible impact of bipolar filtering in visual prostheses with 3 or more levels of grayscale. Recognition rates were higher with bipolar edge images and the improvement was significant in scenes with complex backgrounds. The results also suggest that erroneous shape from shading interpretation of bipolar edges resulting from pigment rather than boundaries of shape may confound the recognition.

  8. Comparing object recognition from binary and bipolar edge images for visual prostheses

    PubMed Central

    Jung, Jae-Hyun; Pu, Tian; Peli, Eli

    2017-01-01

    Visual prostheses require an effective representation method due to the limited display condition which has only 2 or 3 levels of grayscale in low resolution. Edges derived from abrupt luminance changes in images carry essential information for object recognition. Typical binary (black and white) edge images have been used to represent features to convey essential information. However, in scenes with a complex cluttered background, the recognition rate of the binary edge images by human observers is limited and additional information is required. The polarity of edges and cusps (black or white features on a gray background) carries important additional information; the polarity may provide shape from shading information missing in the binary edge image. This depth information may be restored by using bipolar edges. We compared object recognition rates from 16 binary edge images and bipolar edge images by 26 subjects to determine the possible impact of bipolar filtering in visual prostheses with 3 or more levels of grayscale. Recognition rates were higher with bipolar edge images and the improvement was significant in scenes with complex backgrounds. The results also suggest that erroneous shape from shading interpretation of bipolar edges resulting from pigment rather than boundaries of shape may confound the recognition. PMID:28458481

  9. Range image segmentation using Zernike moment-based generalized edge detector

    NASA Technical Reports Server (NTRS)

    Ghosal, S.; Mehrotra, R.

    1992-01-01

    The authors proposed a novel Zernike moment-based generalized step edge detection method which can be used for segmenting range and intensity images. A generalized step edge detector is developed to identify different kinds of edges in range images. These edge maps are thinned and linked to provide final segmentation. A generalized edge is modeled in terms of five parameters: orientation, two slopes, one step jump at the location of the edge, and the background gray level. Two complex and two real Zernike moment-based masks are required to determine all these parameters of the edge model. Theoretical noise analysis is performed to show that these operators are quite noise tolerant. Experimental results are included to demonstrate edge-based segmentation technique.

  10. Mechanism of Pressure-Induced Phase Transitions, Amorphization, and Absorption-Edge Shift in Photovoltaic Methylammonium Lead Iodide.

    PubMed

    Szafrański, Marek; Katrusiak, Andrzej

    2016-09-01

    Our single-crystal X-ray diffraction study of methylammonium lead triiodide, MAPbI3, provides the first comprehensive structural information on the tetragonal phase II in the pressure range to 0.35 GPa, on the cubic phase IV stable between 0.35 and 2.5 GPa, and on the isostructural cubic phase V observed above 2.5 GPa, which undergoes a gradual amorphization. The optical absorption study confirms that up to 0.35 GPa, the absorption edge of MAPbI3 is red-shifted, allowing an extension of spectral absorption. The transitions to phases IV and V are associated with the abrupt blue shifts of the absorption edge. The strong increase of the energy gap in phase V result in a spectacular color change of the crystal from black to red around 3.5 GPa. The optical changes have been correlated with the pressure-induced strain of the MAPbI3 inorganic framework and its frustration, triggered by methylammonium cations trapped at random orientations in the squeezed voids.

  11. Simulation of Near-Edge X-ray Absorption Fine Structure with Time-Dependent Equation-of-Motion Coupled-Cluster Theory.

    PubMed

    Nascimento, Daniel R; DePrince, A Eugene

    2017-07-06

    An explicitly time-dependent (TD) approach to equation-of-motion (EOM) coupled-cluster theory with single and double excitations (CCSD) is implemented for simulating near-edge X-ray absorption fine structure in molecular systems. The TD-EOM-CCSD absorption line shape function is given by the Fourier transform of the CCSD dipole autocorrelation function. We represent this transform by its Padé approximant, which provides converged spectra in much shorter simulation times than are required by the Fourier form. The result is a powerful framework for the blackbox simulation of broadband absorption spectra. K-edge X-ray absorption spectra for carbon, nitrogen, and oxygen in several small molecules are obtained from the real part of the absorption line shape function and are compared with experiment. The computed and experimentally obtained spectra are in good agreement; the mean unsigned error in the predicted peak positions is only 1.2 eV. We also explore the spectral signatures of protonation in these molecules.

  12. Correction of absorption-edge artifacts in polychromatic X-ray tomography in a scanning electron microscope for 3D microelectronics

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Laloum, D., E-mail: david.laloum@cea.fr; CEA, LETI, MINATEC Campus, 17 rue des Martyrs, 38054 Grenoble Cedex 9; STMicroelectronics, 850 rue Jean Monnet, 38926 Crolles

    2015-01-15

    X-ray tomography is widely used in materials science. However, X-ray scanners are often based on polychromatic radiation that creates artifacts such as dark streaks. We show this artifact is not always due to beam hardening. It may appear when scanning samples with high-Z elements inside a low-Z matrix because of the high-Z element absorption edge: X-rays whose energy is above this edge are strongly absorbed, violating the exponential decay assumption for reconstruction algorithms and generating dark streaks. A method is proposed to limit the absorption edge effect and is applied on a microelectronic case to suppress dark streaks between interconnections.

  13. X-ray Absorption and Emission Spectroscopy of CrIII (Hydr)Oxides: Analysis of the K-Pre-Edge Region

    NASA Astrophysics Data System (ADS)

    Frommer, Jakob; Nachtegaal, Maarten; Czekaj, Izabela; Weng, Tsu-Chien; Kretzschmar, Ruben

    2009-10-01

    Pre-edge spectral features below the main X-ray absorption K-edge of transition metals show a pronounced chemical sensitivity and are promising sources of structural information. Nevertheless, the use of pre-edge analysis in applied research is limited because of the lack of definite theoretical peak-assignments. The aim of this study was to determine the factors affecting the chromium K-pre-edge features in trivalent chromium-bearing oxides and oxyhydroxides. The selected phases varied in the degree of octahedral polymerization and the degree of iron-for-chromium substitution in the crystal structure. We investigated the pre-edge fine structure by means of high-energy-resolution fluorescence detected X-ray absorption spectroscopy and by 1s2p resonant X-ray emission spectroscopy. Multiplet theory and full multiple-scattering calculations were used to analyze the experimental data. We show that the chromium K-pre-edge contains localized and nonlocalized transitions. Contributions arising from nonlocalized metal-metal transitions are sensitive to the nearest metal type and to the linkage mode between neighboring metal octahedra. Analyzing these transitions opens up new opportunities for investigating the local coordination environment of chromium in poorly ordered solids of environmental relevance.

  14. Experimental observation of the shift and width of the aluminium K absorption edge in laser shock-compressed plasmas

    NASA Astrophysics Data System (ADS)

    Hall, T. A.; Al-Kuzee, J.; Benuzzi, A.; Koenig, M.; Krishnan, J.; Grandjouan, N.; Batani, D.; Bossi, S.; Nicolella, S.

    1998-03-01

    Experimental measurements of the shift and width of the aluminium K-absorption edge in laser shock-compressed plasma is presented. The spectrometer used in these experiments allows an accurate wavelength calibration and fiduciary and hence provides precise measurements of both the shift and the width of the absorption edge. Results have been obtained for compressions up to approximately ×2 and temperatures up to about 1.5 eV. The values of shift and width are compared with a new model with which there is very good agreement.

  15. Temperature dependence of the fundamental optical absorption edge in crystals and disordered semiconductors

    NASA Astrophysics Data System (ADS)

    Grein, C. H.; John, Sajeev

    1989-04-01

    We present a first principles theory of the temperature dependence of the Urbach optical absorption edge in crystals and disordered semiconductors which incorporates the effects of short range correlated static disorder and the non-adiabatic quantum dynamics of the coupled electron-phonon system. At finite temperatures the dominant features of the Urbach tail are accounted for by multiple phonon absorption and emission side bands which accompany the optically induced electronic transition and which provide a dynamic polaronic potential well that localizes the electron. Excellent agreement is found with experimental data on both crystalline and amorphous silicon.

  16. Edge detection based on computational ghost imaging with structured illuminations

    NASA Astrophysics Data System (ADS)

    Yuan, Sheng; Xiang, Dong; Liu, Xuemei; Zhou, Xin; Bing, Pibin

    2018-03-01

    Edge detection is one of the most important tools to recognize the features of an object. In this paper, we propose an optical edge detection method based on computational ghost imaging (CGI) with structured illuminations which are generated by an interference system. The structured intensity patterns are designed to make the edge of an object be directly imaged from detected data in CGI. This edge detection method can extract the boundaries for both binary and grayscale objects in any direction at one time. We also numerically test the influence of distance deviations in the interference system on edge extraction, i.e., the tolerance of the optical edge detection system to distance deviation. Hopefully, it may provide a guideline for scholars to build an experimental system.

  17. Calculation of optical and K pre-edge absorption spectra for ferrous iron of distorted sites in oxide crystals

    NASA Astrophysics Data System (ADS)

    Vercamer, Vincent; Hunault, Myrtille O. J. Y.; Lelong, Gérald; Haverkort, Maurits W.; Calas, Georges; Arai, Yusuke; Hijiya, Hiroyuki; Paulatto, Lorenzo; Brouder, Christian; Arrio, Marie-Anne; Juhin, Amélie

    2016-12-01

    Advanced semiempirical calculations have been performed to compute simultaneously optical absorption and K pre-edge x-ray absorption spectra of Fe2 + in four distinct site symmetries found in minerals. The four symmetries, i.e., a distorted octahedron, a distorted tetrahedron, a square planar site, and a trigonal bipyramidal site, are representative of the Fe2 + sites found in crystals and glasses. A particular attention has been paid to the definition of the p -d hybridization Hamiltonian which occurs for noncentrosymmetric symmetries in order to account for electric dipole transitions. For the different sites under study, an excellent agreement between calculations and experiments was found for both optical and x-ray absorption spectra, in particular in terms of relative intensities and energy positions of electronic transitions. To our knowledge, these are the first calculations of optical absorption spectra on Fe2 + placed in such diverse site symmetries, including centrosymmetric sites. The proposed theoretical model should help to interpret the features of both the optical absorption and the K pre-edge absorption spectra of 3 d transition metal ions and to go beyond the usual fingerprint interpretation.

  18. Wavelet domain image restoration with adaptive edge-preserving regularization.

    PubMed

    Belge, M; Kilmer, M E; Miller, E L

    2000-01-01

    In this paper, we consider a wavelet based edge-preserving regularization scheme for use in linear image restoration problems. Our efforts build on a collection of mathematical results indicating that wavelets are especially useful for representing functions that contain discontinuities (i.e., edges in two dimensions or jumps in one dimension). We interpret the resulting theory in a statistical signal processing framework and obtain a highly flexible framework for adapting the degree of regularization to the local structure of the underlying image. In particular, we are able to adapt quite easily to scale-varying and orientation-varying features in the image while simultaneously retaining the edge preservation properties of the regularizer. We demonstrate a half-quadratic algorithm for obtaining the restorations from observed data.

  19. Edge enhancement of color images using a digital micromirror device.

    PubMed

    Di Martino, J Matías; Flores, Jorge L; Ayubi, Gastón A; Alonso, Julia R; Fernández, Ariel; Ferrari, José A

    2012-06-01

    A method for orientation-selective enhancement of edges in color images is proposed. The method utilizes the capacity of digital micromirror devices to generate a positive and a negative color replica of the image used as input. When both images are slightly displaced and imagined together, one obtains an image with enhanced edges. The proposed technique does not require a coherent light source or precise alignment. The proposed method could be potentially useful for processing large image sequences in real time. Validation experiments are presented.

  20. Mn K-Edge X-ray Absorption Studies of Oxo- and Hydroxo-manganese(IV) Complexes: Experimental and Theoretical Insights into Pre-Edge Properties

    PubMed Central

    2015-01-01

    Mn K-edge X-ray absorption spectroscopy (XAS) was used to gain insights into the geometric and electronic structures of [MnII(Cl)2(Me2EBC)], [MnIV(OH)2(Me2EBC)]2+, and [MnIV(O)(OH)(Me2EBC)]+, which are all supported by the tetradentate, macrocyclic Me2EBC ligand (Me2EBC = 4,11-dimethyl-1,4,8,11-tetraazabicyclo[6.6.2]hexadecane). Analysis of extended X-ray absorption fine structure (EXAFS) data for [MnIV(O)(OH)(Me2EBC)]+ revealed Mn–O scatterers at 1.71 and 1.84 Å and Mn–N scatterers at 2.11 Å, providing the first unambiguous support for the formulation of this species as an oxohydroxomanganese(IV) adduct. EXAFS-determined structural parameters for [MnII(Cl)2(Me2EBC)] and [MnIV(OH)2(Me2EBC)]2+ are consistent with previously reported crystal structures. The Mn pre-edge energies and intensities of these complexes were examined within the context of data for other oxo- and hydroxomanganese(IV) adducts, and time-dependent density functional theory (TD-DFT) computations were used to predict pre-edge properties for all compounds considered. This combined experimental and computational analysis revealed a correlation between the Mn–O(H) distances and pre-edge peak areas of MnIV=O and MnIV–OH complexes, but this trend was strongly modulated by the MnIV coordination geometry. Mn 3d-4p mixing, which primarily accounts for the pre-edge intensities, is not solely a function of the Mn–O(H) bond length; the coordination geometry also has a large effect on the distribution of pre-edge intensity. For tetragonal MnIV=O centers, more than 90% of the pre-edge intensity comes from excitations to the Mn=O σ* MO. Trigonal bipyramidal oxomanganese(IV) centers likewise feature excitations to the Mn=O σ* molecular orbital (MO) but also show intense transitions to 3dx2–y2 and 3dxy MOs because of enhanced 3d-4px,y mixing. This gives rise to a broader pre-edge feature for trigonal MnIV=O adducts. These results underscore the importance of reporting experimental pre-edge areas

  1. Mn K-edge X-ray absorption studies of oxo- and hydroxo-manganese(IV) complexes: experimental and theoretical insights into pre-edge properties.

    PubMed

    Leto, Domenick F; Jackson, Timothy A

    2014-06-16

    Mn K-edge X-ray absorption spectroscopy (XAS) was used to gain insights into the geometric and electronic structures of [Mn(II)(Cl)2(Me2EBC)], [Mn(IV)(OH)2(Me2EBC)](2+), and [Mn(IV)(O)(OH)(Me2EBC)](+), which are all supported by the tetradentate, macrocyclic Me2EBC ligand (Me2EBC = 4,11-dimethyl-1,4,8,11-tetraazabicyclo[6.6.2]hexadecane). Analysis of extended X-ray absorption fine structure (EXAFS) data for [Mn(IV)(O)(OH)(Me2EBC)](+) revealed Mn-O scatterers at 1.71 and 1.84 Å and Mn-N scatterers at 2.11 Å, providing the first unambiguous support for the formulation of this species as an oxohydroxomanganese(IV) adduct. EXAFS-determined structural parameters for [Mn(II)(Cl)2(Me2EBC)] and [Mn(IV)(OH)2(Me2EBC)](2+) are consistent with previously reported crystal structures. The Mn pre-edge energies and intensities of these complexes were examined within the context of data for other oxo- and hydroxomanganese(IV) adducts, and time-dependent density functional theory (TD-DFT) computations were used to predict pre-edge properties for all compounds considered. This combined experimental and computational analysis revealed a correlation between the Mn-O(H) distances and pre-edge peak areas of Mn(IV)═O and Mn(IV)-OH complexes, but this trend was strongly modulated by the Mn(IV) coordination geometry. Mn 3d-4p mixing, which primarily accounts for the pre-edge intensities, is not solely a function of the Mn-O(H) bond length; the coordination geometry also has a large effect on the distribution of pre-edge intensity. For tetragonal Mn(IV)═O centers, more than 90% of the pre-edge intensity comes from excitations to the Mn═O σ* MO. Trigonal bipyramidal oxomanganese(IV) centers likewise feature excitations to the Mn═O σ* molecular orbital (MO) but also show intense transitions to 3dx(2)-y(2) and 3dxy MOs because of enhanced 3d-4px,y mixing. This gives rise to a broader pre-edge feature for trigonal Mn(IV)═O adducts. These results underscore the importance of

  2. Probing ultrafast ππ*/nπ* internal conversion in organic chromophores via K-edge resonant absorption

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wolf, T. J. A.; Myhre, R. H.; Cryan, J. P.

    Many photoinduced processes including photosynthesis and human vision happen in organic molecules and involve coupled femtosecond dynamics of nuclei and electrons. Organic molecules with heteroatoms often possess an important excited-state relaxation channel from an optically allowed ππ* to a dark nπ* state. The ππ*/nπ* internal conversion is difficult to investigate, as most spectroscopic methods are not exclusively sensitive to changes in the excited-state electronic structure. Here, we report achieving the required sensitivity by exploiting the element and site specificity of near-edge soft X-ray absorption spectroscopy. As a hole forms in the n orbital during ππ*/nπ* internal conversion, the absorption spectrummore » at the heteroatom K-edge exhibits an additional resonance. We demonstrate the concept using the nucleobase thymine at the oxygen K-edge, and unambiguously show that ππ*/nπ* internal conversion takes place within (60 ± 30) fs. Furthermore, high-level-coupled cluster calculations confirm the method’s impressive electronic structure sensitivity for excited-state investigations.« less

  3. Probing ultrafast ππ*/nπ* internal conversion in organic chromophores via K-edge resonant absorption

    DOE PAGES

    Wolf, T. J. A.; Myhre, R. H.; Cryan, J. P.; ...

    2017-06-22

    Many photoinduced processes including photosynthesis and human vision happen in organic molecules and involve coupled femtosecond dynamics of nuclei and electrons. Organic molecules with heteroatoms often possess an important excited-state relaxation channel from an optically allowed ππ* to a dark nπ* state. The ππ*/nπ* internal conversion is difficult to investigate, as most spectroscopic methods are not exclusively sensitive to changes in the excited-state electronic structure. Here, we report achieving the required sensitivity by exploiting the element and site specificity of near-edge soft X-ray absorption spectroscopy. As a hole forms in the n orbital during ππ*/nπ* internal conversion, the absorption spectrummore » at the heteroatom K-edge exhibits an additional resonance. We demonstrate the concept using the nucleobase thymine at the oxygen K-edge, and unambiguously show that ππ*/nπ* internal conversion takes place within (60 ± 30) fs. Furthermore, high-level-coupled cluster calculations confirm the method’s impressive electronic structure sensitivity for excited-state investigations.« less

  4. Estimation of contrast of refraction contrast imaging compared with absorption imaging-basic approach.

    PubMed

    Hirano, Masatsugu; Yamasaki, Katsuhito; Okada, Hiroshi; Kitazawa, Sohei; Kitazawa, Riko; Ohno, Yoshiharu; Sakurai, Takashi; Kondoh, Takeshi; Ohbayashi, Chiho; Katafuchi, Tetsuro; Maeda, Sakan; Sugimura, Kazuro; Tamura, Shinichi

    2005-03-01

    We discuss the usefulness of the refraction contrast method using highly parallel X-rays as a new approach to minute lung cancer detection. The advantages of refraction contrast images are discussed in terms of contrast, and a comparison is made with absorption images. We simulated refraction contrast imaging using globules with the density of water in air as models for minute lung cancer detection. The contrast intensified by bright and dark lines was compared on a globule with the contrast of absorption images. We adopted the Monte Carlo simulation to determine the strength of the profile curve of the photon counts at the detector. The obtained contrasts were more intense by two to three digits than those obtainable with the absorption contrast imaging method. The contrast in refraction contrast imaging was more intense than that obtainable with absorption contrast imaging. A two to three digit improvement in contrast means that it is possible to greatly reduce the exposure dose necessary for imaging. Therefore, it is expected to become possible to detect the interfaces of soft tissues, which are difficult to capture with conventional absorption imaging, at low dosages and high resolution.

  5. Edge Extraction by an Exponential Function Considering X-ray Transmission Characteristics

    NASA Astrophysics Data System (ADS)

    Kim, Jong Hyeong; Youp Synn, Sang; Cho, Sung Man; Jong Joo, Won

    2011-04-01

    3-D radiographic methodology has been into the spotlight for quality inspection of mass product or in-service inspection of aging product. To locate a target object in 3-D space, its characteristic contours such as edge length, edge angle, and vertices are very important. In spite of a simple geometry product, it is very difficult to get clear shape contours from a single radiographic image. The image contains scattering noise at the edges and ambiguity coming from X-Ray absorption within the body. This article suggests a concise method to extract whole edges from a single X-ray image. At the edge point of the object, the intensity of the X-ray decays exponentially as the X-ray penetrates the object. Considering this X-Ray decaying property, edges are extracted by using the least square fitting with the control of Coefficient of Determination.

  6. The ship edge feature detection based on high and low threshold for remote sensing image

    NASA Astrophysics Data System (ADS)

    Li, Xuan; Li, Shengyang

    2018-05-01

    In this paper, a method based on high and low threshold is proposed to detect the ship edge feature due to the low accuracy rate caused by the noise. Analyze the relationship between human vision system and the target features, and to determine the ship target by detecting the edge feature. Firstly, using the second-order differential method to enhance the quality of image; Secondly, to improvement the edge operator, we introduction of high and low threshold contrast to enhancement image edge and non-edge points, and the edge as the foreground image, non-edge as a background image using image segmentation to achieve edge detection, and remove the false edges; Finally, the edge features are described based on the result of edge features detection, and determine the ship target. The experimental results show that the proposed method can effectively reduce the number of false edges in edge detection, and has the high accuracy of remote sensing ship edge detection.

  7. The crack detection algorithm of pavement image based on edge information

    NASA Astrophysics Data System (ADS)

    Yang, Chunde; Geng, Mingyue

    2018-05-01

    As the images of pavement cracks are affected by a large amount of complicated noises, such as uneven illumination and water stains, the detected cracks are discontinuous and the main body information at the edge of the cracks is easily lost. In order to solve the problem, a crack detection algorithm in pavement image based on edge information is proposed. Firstly, the image is pre-processed by the nonlinear gray-scale transform function and reconstruction filter to enhance the linear characteristic of the crack. At the same time, an adaptive thresholding method is designed to coarsely extract the cracks edge according to the gray-scale gradient feature and obtain the crack gradient information map. Secondly, the candidate edge points are obtained according to the gradient information, and the edge is detected based on the single pixel percolation processing, which is improved by using the local difference between pixels in the fixed region. Finally, complete crack is obtained by filling the crack edge. Experimental results show that the proposed method can accurately detect pavement cracks and preserve edge information.

  8. Understanding the shrinkage of optical absorption edges of nanostructured Cd-Zn sulphide films for photothermal applications

    NASA Astrophysics Data System (ADS)

    Hossain, Md. Sohrab; Kabir, Humayun; Rahman, M. Mahbubur; Hasan, Kamrul; Bashar, Muhammad Shahriar; Rahman, Mashudur; Gafur, Md. Abdul; Islam, Shariful; Amri, Amun; Jiang, Zhong-Tao; Altarawneh, Mohammednoor; Dlugogorski, Bogdan Z.

    2017-01-01

    In this article Cd-Zn sulphide thin films deposited onto soda lime glass substrates via chemical bath deposition (CBD) technique were investigated for photovoltaic applications. The synthesized films were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), and ultraviolet visible (UV-vis) spectroscopic methodologies. A higher degree of crystallinity of the films was attained with the increase of film thicknesses. SEM micrographs exhibited a partial crystalline structure with a particulate appearance surrounded by the amorphous grain boundaries. The optical absorbance and absorption coefficient of the films were also enhanced significantly with the increase in film thicknesses. Optical band-gap analysis indicated a monotonic decrease in direct and indirect band-gaps with the increase of thicknesses of the films. The presence of direct and indirect transitional energies due to the exponential falling edges of the absorption curves may either be due to the lack of long-range order or to the existence of defects in the films. The declination of the optical absorption edges was also confirmed via Urbach energy and steepness parameters studies.

  9. Edge detection of optical subaperture image based on improved differential box-counting method

    NASA Astrophysics Data System (ADS)

    Li, Yi; Hui, Mei; Liu, Ming; Dong, Liquan; Kong, Lingqin; Zhao, Yuejin

    2018-01-01

    Optical synthetic aperture imaging technology is an effective approach to improve imaging resolution. Compared with monolithic mirror system, the image of optical synthetic aperture system is often more complex at the edge, and as a result of the existence of gap between segments, which makes stitching becomes a difficult problem. So it is necessary to extract the edge of subaperture image for achieving effective stitching. Fractal dimension as a measure feature can describe image surface texture characteristics, which provides a new approach for edge detection. In our research, an improved differential box-counting method is used to calculate fractal dimension of image, then the obtained fractal dimension is mapped to grayscale image to detect edges. Compared with original differential box-counting method, this method has two improvements as follows: by modifying the box-counting mechanism, a box with a fixed height is replaced by a box with adaptive height, which solves the problem of over-counting the number of boxes covering image intensity surface; an image reconstruction method based on super-resolution convolutional neural network is used to enlarge small size image, which can solve the problem that fractal dimension can't be calculated accurately under the small size image, and this method may well maintain scale invariability of fractal dimension. The experimental results show that the proposed algorithm can effectively eliminate noise and has a lower false detection rate compared with the traditional edge detection algorithms. In addition, this algorithm can maintain the integrity and continuity of image edge in the case of retaining important edge information.

  10. A Semi-Automatic Method for Image Analysis of Edge Dynamics in Living Cells

    PubMed Central

    Huang, Lawrence; Helmke, Brian P.

    2011-01-01

    Spatial asymmetry of actin edge ruffling contributes to the process of cell polarization and directional migration, but mechanisms by which external cues control actin polymerization near cell edges remain unclear. We designed a quantitative image analysis strategy to measure the spatiotemporal distribution of actin edge ruffling. Time-lapse images of endothelial cells (ECs) expressing mRFP-actin were segmented using an active contour method. In intensity line profiles oriented normal to the cell edge, peak detection identified the angular distribution of polymerized actin within 1 µm of the cell edge, which was localized to lamellipodia and edge ruffles. Edge features associated with filopodia and peripheral stress fibers were removed. Circular statistical analysis enabled detection of cell polarity, indicated by a unimodal distribution of edge ruffles. To demonstrate the approach, we detected a rapid, nondirectional increase in edge ruffling in serum-stimulated ECs and a change in constitutive ruffling orientation in quiescent, nonpolarized ECs. Error analysis using simulated test images demonstrate robustness of the method to variations in image noise levels, edge ruffle arc length, and edge intensity gradient. These quantitative measurements of edge ruffling dynamics enable investigation at the cellular length scale of the underlying molecular mechanisms regulating actin assembly and cell polarization. PMID:21643526

  11. Isotope effects in liquid water probed by transmission mode x-ray absorption spectroscopy at the oxygen K-edge.

    PubMed

    Schreck, Simon; Wernet, Philippe

    2016-09-14

    The effects of isotope substitution in liquid water are probed by x-ray absorption spectroscopy at the O K-edge as measured in transmission mode. Confirming earlier x-ray Raman scattering experiments, the D2O spectrum is found to be blue shifted with respect to H2O, and the D2O spectrum to be less broadened. Following the earlier interpretations of UV and x-ray Raman spectra, the shift is related to the difference in ground-state zero-point energies between D2O and H2O, while the difference in broadening is related to the difference in ground-state vibrational zero-point distributions. We demonstrate that the transmission-mode measurements allow for determining the spectral shapes with unprecedented accuracy. Owing in addition to the increased spectral resolution and signal to noise ratio compared to the earlier measurements, the new data enable the stringent determination of blue shift and broadening in the O K-edge x-ray absorption spectrum of liquid water upon isotope substitution. The results are compared to UV absorption data, and it is discussed to which extent they reflect the differences in zero-point energies and vibrational zero-point distributions in the ground-states of the liquids. The influence of the shape of the final-state potential, inclusion of the Franck-Condon structure, and differences between liquid H2O and D2O resulting from different hydrogen-bond environments in the liquids are addressed. The differences between the O K-edge absorption spectra of water from our transmission-mode measurements and from the state-of-the-art x-ray Raman scattering experiments are discussed in addition. The experimentally extracted values of blue shift and broadening are proposed to serve as a test for calculations of ground-state zero-point energies and vibrational zero-point distributions in liquid H2O and D2O. This clearly motivates the need for new calculations of the O K-edge x-ray absorption spectrum of liquid water.

  12. Multi-epoch Detections of Water Ice Absorption in Edge-on Disks around Herbig Ae Stars: PDS 144N and PDS 453

    NASA Astrophysics Data System (ADS)

    Terada, Hiroshi; Tokunaga, Alan T.

    2017-01-01

    We report the multi-epoch detections of water ice in 2.8-4.2 μ {{m}} spectra of two Herbig Ae stars, PDS 144N (A2 IVe) and PDS 453 (F2 Ve), which have an edge-on circumstellar disk. The detected water ice absorption is found to originate from their protoplanetary disks. The spectra show a relatively shallow absorption of water ice of around 3.1 μ {{m}} for both objects. The optical depths of the water ice absorption are ˜0.1 and ˜0.2 for PDS 144N and PDS 453, respectively. Compared to the water ice previously detected in low-mass young stellar objects with an edge-on disk with a similar inclination angle, these optical depths are significantly lower. It suggests that stronger UV radiation from the central stars effectively decreases the water ice abundance around the Herbig Ae stars through photodesorption. The water ice absorption in PDS 453 shows a possible variation of the feature among the six observing epochs. This variation could be due to a change of absorption materials passing through our line of sight to the central star. The overall profile of the water ice absorption in PDS 453 is quite similar to the absorption previously reported in the edge-on disk object d216-0939, and this unique profile may be seen only at a high inclination angle in the range of 76°-80°.

  13. Edge detection - Image-plane versus digital processing

    NASA Technical Reports Server (NTRS)

    Huck, Friedrich O.; Fales, Carl L.; Park, Stephen K.; Triplett, Judith A.

    1987-01-01

    To optimize edge detection with the familiar Laplacian-of-Gaussian operator, it has become common to implement this operator with a large digital convolution mask followed by some interpolation of the processed data to determine the zero crossings that locate edges. It is generally recognized that this large mask causes substantial blurring of fine detail. It is shown that the spatial detail can be improved by a factor of about four with either the Wiener-Laplacian-of-Gaussian filter or an image-plane processor. The Wiener-Laplacian-of-Gaussian filter minimizes the image-gathering degradations if the scene statistics are at least approximately known and also serves as an interpolator to determine the desired zero crossings directly. The image-plane processor forms the Laplacian-of-Gaussian response by properly combining the optical design of the image-gathering system with a minimal three-by-three lateral-inhibitory processing mask. This approach, which is suggested by Marr's model of early processing in human vision, also reduces data processing by about two orders of magnitude and data transmission by up to an order of magnitude.

  14. Iron K-edge X-ray absorption near-edge structure spectroscopy of aerodynamically levitated silicate melts and glasses

    DOE PAGES

    Alderman, O. L. G.; Wilding, M. C.; Tamalonis, A.; ...

    2017-01-26

    Here, the local structure about Fe(II) and Fe(III) in silicate melts was investigated in-situ using iron K-edge X-ray absorption near-edge structure (XANES) spectroscopy. An aerodynamic levitation and laser heating system was used to allow access to high temperatures without contamination, and was combined with a chamber and gas mixing system to allow the iron oxidation state, Fe 3+/ΣFe, to be varied by systematic control of the atmospheric oxygen fugacity. Eleven alkali-free, mostly iron-rich and depolymerized base compositions were chosen for the experiments, including pure oxide FeO, olivines (Fe,Mg) 2SiO 4, pyroxenes (Fe,Mg)SiO 3, calcic FeO-CaSiO 3, and a calcium aluminosilicatemore » composition, where total iron content is denoted by FeO for convenience. Melt temperatures varied between 1410 and 2160 K and oxygen fugacities between FMQ – 2.3(3) to FMQ + 9.1(3) log units (uncertainties in parentheses) relative to the fayalite-magnetite-β-quartz (FMQ) buffer.« less

  15. Photon counting x-ray imaging with K-edge filtered x-rays: A simulation study.

    PubMed

    Atak, Haluk; Shikhaliev, Polad M

    2016-03-01

    In photon counting (PC) x-ray imaging and computed tomography (CT), the broad x-ray spectrum can be split into two parts using an x-ray filter with appropriate K-edge energy, which can improve material decomposition. Recent experimental study has demonstrated substantial improvement in material decomposition with PC CT when K-edge filtered x-rays were used. The purpose of the current work was to conduct further investigations of the K-edge filtration method using comprehensive simulation studies. The study was performed in the following aspects: (1) optimization of the K-edge filter for a particular imaging configuration, (2) effects of the K-edge filter parameters on material decomposition, (3) trade-off between the energy bin separation, tube load, and beam quality with K-edge filter, (4) image quality of general (unsubtracted) images when a K-edge filter is used to improve dual energy (DE) subtracted images, and (5) improvements with K-edge filtered x-rays when PC detector has limited energy resolution. The PC x-ray images of soft tissue phantoms with 15 and 30 cm thicknesses including iodine, CaCO3, and soft tissue contrast materials, were simulated. The signal to noise ratio (SNR) of the contrast elements was determined in general and material-decomposed images using K-edge filters with different atomic numbers and thicknesses. The effect of the filter atomic number and filter thickness on energy separation factor and SNR was determined. The boundary conditions for the tube load and halfvalue layer were determined when the K-edge filters are used. The material-decomposed images were also simulated using PC detector with limited energy resolution, and improvements with K-edge filtered x-rays were quantified. The K-edge filters with atomic numbers from 56 to 71 and K-edge energies 37.4-63.4 keV, respectively, can be used for tube voltages from 60 to 150 kVp, respectively. For a particular tube voltage of 120 kVp, the Gd and Ho were the optimal filter materials

  16. An Interactive Procedure to Preserve the Desired Edges during the Image Processing of Noise Reduction

    NASA Astrophysics Data System (ADS)

    Hsu, Chih-Yu; Huang, Hsuan-Yu; Lee, Lin-Tsang

    2010-12-01

    The paper propose a new procedure including four stages in order to preserve the desired edges during the image processing of noise reduction. A denoised image can be obtained from a noisy image at the first stage of the procedure. At the second stage, an edge map can be obtained by the Canny edge detector to find the edges of the object contours. Manual modification of an edge map at the third stage is optional to capture all the desired edges of the object contours. At the final stage, a new method called Edge Preserved Inhomogeneous Diffusion Equation (EPIDE) is used to smooth the noisy images or the previously denoised image at the first stage for achieving the edge preservation. The Optical Character Recognition (OCR) results in the experiments show that the proposed procedure has the best recognition result because of the capability of edge preservation.

  17. Edge Turbulence Imaging in Alcator C-Mod

    NASA Astrophysics Data System (ADS)

    Zweben, Stewart J.

    2001-10-01

    This talk will describe measurements and modeling of the 2-D structure of edge turbulence in Alcator C-Mod. The radial vs. poloidal structure was measured using Gas Puff Imaging (GPI) (R. Maqueda et al, RSI 72, 931 (2001), J. Terry et al, J. Nucl. Materials 290-293, 757 (2001)), in which the visible light emitted by an edge neutral gas puff (generally D or He) is viewed along the local magnetic field by a fast-gated video camera. Strong fluctuations are observed in the gas cloud light emission when the camera is gated at ~2 microsec exposure time per frame. The structure of these fluctuations is highly turbulent with a typical radial and poloidal scale of ≈1 cm, and often with local maxima in the scrape-off layer (i.e. ``blobs"). Video clips and analyses of these images will be presented along with their variation in different plasma regimes. The local time dependence of edge turbulence is measured using high-speed photodiodes viewing the gas puff emission, a scanning Langmuir probe, and also with a Princeton Scientific Instruments ultra-fast framing camera, which can make 2-D images the gas puff at up to 200,000 frames/sec. Probe measurements show that the strong turbulence region moves to the separatrix as the density limit is approached, which may be connected to the density limit (B. LaBombard et al., Phys. Plasmas 8 2107 (2001)). Comparisons of this C-Mod turbulence data will be made with results of simulations from the Drift-Ballooning Mode (DBM) (B.N. Rogers et al, Phys. Rev. Lett. 20 4396 (1998))and Non-local Edge Turbulence (NLET) codes.

  18. Near-edge x-ray absorption fine structure spectroscopy at atmospheric pressure with a table-top laser-induced soft x-ray source

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kühl, Frank-Christian, E-mail: Frank-christian.kuehl@mail.de; Müller, Matthias, E-mail: matthias.mueller@llg-ev.de; Schellhorn, Meike

    2016-07-15

    The authors present a table-top soft x-ray absorption spectrometer, accomplishing investigations of the near-edge x-ray absorption fine structure (NEXAFS) in a laboratory environment. The system is based on a low debris plasma ignited by a picosecond laser in a pulsed krypton gas jet, emitting soft x-ray radiation in the range from 1 to 5 nm. For absorption spectroscopy in and around the “water window” (2.3–4.4 nm), a compact helium purged sample compartment for experiments at atmospheric pressure has been constructed and tested. NEXAFS measurements on CaCl{sub 2} and KMnO{sub 4} samples were conducted at the calcium and manganese L-edges, as well asmore » at the oxygen K-edge in air, atmospheric helium, and under vacuum, respectively. The results indicate the importance of atmospheric conditions for an investigation of sample hydration processes.« less

  19. ESIM: Edge Similarity for Screen Content Image Quality Assessment.

    PubMed

    Ni, Zhangkai; Ma, Lin; Zeng, Huanqiang; Chen, Jing; Cai, Canhui; Ma, Kai-Kuang

    2017-10-01

    In this paper, an accurate full-reference image quality assessment (IQA) model developed for assessing screen content images (SCIs), called the edge similarity (ESIM), is proposed. It is inspired by the fact that the human visual system (HVS) is highly sensitive to edges that are often encountered in SCIs; therefore, essential edge features are extracted and exploited for conducting IQA for the SCIs. The key novelty of the proposed ESIM lies in the extraction and use of three salient edge features-i.e., edge contrast, edge width, and edge direction. The first two attributes are simultaneously generated from the input SCI based on a parametric edge model, while the last one is derived directly from the input SCI. The extraction of these three features will be performed for the reference SCI and the distorted SCI, individually. The degree of similarity measured for each above-mentioned edge attribute is then computed independently, followed by combining them together using our proposed edge-width pooling strategy to generate the final ESIM score. To conduct the performance evaluation of our proposed ESIM model, a new and the largest SCI database (denoted as SCID) is established in our work and made to the public for download. Our database contains 1800 distorted SCIs that are generated from 40 reference SCIs. For each SCI, nine distortion types are investigated, and five degradation levels are produced for each distortion type. Extensive simulation results have clearly shown that the proposed ESIM model is more consistent with the perception of the HVS on the evaluation of distorted SCIs than the multiple state-of-the-art IQA methods.

  20. Ultrasound image edge detection based on a novel multiplicative gradient and Canny operator.

    PubMed

    Zheng, Yinfei; Zhou, Yali; Zhou, Hao; Gong, Xiaohong

    2015-07-01

    To achieve the fast and accurate segmentation of ultrasound image, a novel edge detection method for speckle noised ultrasound images was proposed, which was based on the traditional Canny and a novel multiplicative gradient operator. The proposed technique combines a new multiplicative gradient operator of non-Newtonian type with the traditional Canny operator to generate the initial edge map, which is subsequently optimized by the following edge tracing step. To verify the proposed method, we compared it with several other edge detection methods that had good robustness to noise, with experiments on the simulated and in vivo medical ultrasound image. Experimental results showed that the proposed algorithm has higher speed for real-time processing, and the edge detection accuracy could be 75% or more. Thus, the proposed method is very suitable for fast and accurate edge detection of medical ultrasound images. © The Author(s) 2014.

  1. Study on Coloration Mechanism of Chinese Ancient Ceramics by X-ray Absorption Near-edge Structure

    NASA Astrophysics Data System (ADS)

    Peng, Y. H.; Xie, Z.; He, J. F.; Liu, Q. H.; Pan, Z. Y.; Cheng, W. R.; Wei, S. Q.

    2013-04-01

    The Fe K-edge X-ray absorption near-edge structure (XANES) spectra of a series of ceramic shards were measured by fluorescence mode to reveal the color-generating techniques of Chinese porcelain. The analysis disclosed relationships among the chemical form of the iron, the firing conditions and the colors of the ceramics. The results indicate that the coloration for different ceramics depend on the valence states of iron as the main color element in glaze and the proportion of Fe2+ and Fe3+ was attributed to the baking technology. The findings provide important information for archaeologist on the coloration researches.

  2. LLSURE: local linear SURE-based edge-preserving image filtering.

    PubMed

    Qiu, Tianshuang; Wang, Aiqi; Yu, Nannan; Song, Aimin

    2013-01-01

    In this paper, we propose a novel approach for performing high-quality edge-preserving image filtering. Based on a local linear model and using the principle of Stein's unbiased risk estimate as an estimator for the mean squared error from the noisy image only, we derive a simple explicit image filter which can filter out noise while preserving edges and fine-scale details. Moreover, this filter has a fast and exact linear-time algorithm whose computational complexity is independent of the filtering kernel size; thus, it can be applied to real time image processing tasks. The experimental results demonstrate the effectiveness of the new filter for various computer vision applications, including noise reduction, detail smoothing and enhancement, high dynamic range compression, and flash/no-flash denoising.

  3. Ca L2,3-edge XANES and Sr K-edge EXAFS study of hydroxyapatite and fossil bone apatite.

    PubMed

    Zougrou, I M; Katsikini, M; Brzhezinskaya, M; Pinakidou, F; Papadopoulou, L; Tsoukala, E; Paloura, E C

    2016-08-01

    Upon burial, the organic and inorganic components of hard tissues such as bone, teeth, and tusks are subjected to various alterations as a result of interactions with the chemical milieu of soil, groundwater, and presence of microorganisms. In this study, simulation of the Ca L 2,3-edge X-ray absorption near edge structure (XANES) spectrum of hydroxyapatite, using the CTM4XAS code, reveals that the different symmetry of the two nonequivalent Ca(1) and Ca(2) sites in the unit cell gives rise to specific spectral features. Moreover, Ca L 2,3-edge XANES spectroscopy is applied in order to assess variations in fossil bone apatite crystallinity due to heavy bacterial alteration and catastrophic mineral dissolution, compared to well-preserved fossil apatite, fresh bone, and geologic apatite reference samples. Fossilization-induced chemical alterations are investigated by means of Ca L 2,3-edge XANES and scanning electron microscopy (SEM) and are related to histological evaluation using optical microscopy images. Finally, the variations in the bonding environment of Sr and its preference for substitution in the Ca(1) or Ca(2) sites upon increasing the Sr/Ca ratio is assessed by Sr K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy.

  4. Ca L2,3-edge XANES and Sr K-edge EXAFS study of hydroxyapatite and fossil bone apatite

    NASA Astrophysics Data System (ADS)

    Zougrou, I. M.; Katsikini, M.; Brzhezinskaya, M.; Pinakidou, F.; Papadopoulou, L.; Tsoukala, E.; Paloura, E. C.

    2016-08-01

    Upon burial, the organic and inorganic components of hard tissues such as bone, teeth, and tusks are subjected to various alterations as a result of interactions with the chemical milieu of soil, groundwater, and presence of microorganisms. In this study, simulation of the Ca L 2,3-edge X-ray absorption near edge structure (XANES) spectrum of hydroxyapatite, using the CTM4XAS code, reveals that the different symmetry of the two nonequivalent Ca(1) and Ca(2) sites in the unit cell gives rise to specific spectral features. Moreover, Ca L 2,3-edge XANES spectroscopy is applied in order to assess variations in fossil bone apatite crystallinity due to heavy bacterial alteration and catastrophic mineral dissolution, compared to well-preserved fossil apatite, fresh bone, and geologic apatite reference samples. Fossilization-induced chemical alterations are investigated by means of Ca L 2,3-edge XANES and scanning electron microscopy (SEM) and are related to histological evaluation using optical microscopy images. Finally, the variations in the bonding environment of Sr and its preference for substitution in the Ca(1) or Ca(2) sites upon increasing the Sr/Ca ratio is assessed by Sr K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy.

  5. A non-reference evaluation method for edge detection of wear particles in ferrograph images

    NASA Astrophysics Data System (ADS)

    Wang, Jingqiu; Bi, Ju; Wang, Lianjun; Wang, Xiaolei

    2018-02-01

    Edges are one of the most important features of wear particles in a ferrograph image and are widely used to extract parameters, recognize types of wear particles, and assist in the identification of the wear mode and severity. Edge detection is a critical step in ferrograph image processing and analysis. Till date, there has been no single algorithm that guarantees the production of good quality edges in ferrograph images for a variety of applications. Therefore, it is desirable to have a reliable evaluation method for measuring the performance of various edge detection algorithms and for aiding in the selection of the optimal parameter and algorithm for ferrographic applications. In this paper, a new non-reference method for the objective evaluation of wear particle edge detection is proposed. In this method, a comprehensive index of edge evaluation is composed of three components, i.e., the reconstruction based similarity sub-index between the original image and the reconstructed image, the confidence degree sub-index used to show the true or false degree of the edge pixels, and the edge form sub-index that is used to determine the direction consistency and width uniformity of the edges. Two experiments are performed to illustrate the validity of the proposed method. First, this method is used to select the best parameters for an edge detection algorithm, and it is then used to compare the results obtained using various edge detection algorithms and determine the best algorithm. Experimental results of various real ferrograph images verify the effectiveness of the proposed method.

  6. Accurate and facile determination of the index of refraction of organic thin films near the carbon 1s absorption edge.

    PubMed

    Yan, Hongping; Wang, Cheng; McCarn, Allison R; Ade, Harald

    2013-04-26

    A practical and accurate method to obtain the index of refraction, especially the decrement δ, across the carbon 1s absorption edge is demonstrated. The combination of absorption spectra scaled to the Henke atomic scattering factor database, the use of the doubly subtractive Kramers-Kronig relations, and high precision specular reflectivity measurements from thin films allow the notoriously difficult-to-measure δ to be determined with high accuracy. No independent knowledge of the film thickness or density is required. High confidence interpolation between relatively sparse measurements of δ across an absorption edge is achieved. Accurate optical constants determined by this method are expected to greatly improve the simulation and interpretation of resonant soft x-ray scattering and reflectivity data. The method is demonstrated using poly(methyl methacrylate) and should be extendable to all organic materials.

  7. Edge enhancement and noise suppression for infrared image based on feature analysis

    NASA Astrophysics Data System (ADS)

    Jiang, Meng

    2018-06-01

    Infrared images are often suffering from background noise, blurred edges, few details and low signal-to-noise ratios. To improve infrared image quality, it is essential to suppress noise and enhance edges simultaneously. To realize it in this paper, we propose a novel algorithm based on feature analysis in shearlet domain. Firstly, as one of multi-scale geometric analysis (MGA), we introduce the theory and superiority of shearlet transform. Secondly, after analyzing the defects of traditional thresholding technique to suppress noise, we propose a novel feature extraction distinguishing image structures from noise well and use it to improve the traditional thresholding technique. Thirdly, with computing the correlations between neighboring shearlet coefficients, the feature attribute maps identifying the weak detail and strong edges are completed to improve the generalized unsharped masking (GUM). At last, experiment results with infrared images captured in different scenes demonstrate that the proposed algorithm suppresses noise efficiently and enhances image edges adaptively.

  8. [Road Extraction in Remote Sensing Images Based on Spectral and Edge Analysis].

    PubMed

    Zhao, Wen-zhi; Luo, Li-qun; Guo, Zhou; Yue, Jun; Yu, Xue-ying; Liu, Hui; Wei, Jing

    2015-10-01

    Roads are typically man-made objects in urban areas. Road extraction from high-resolution images has important applications for urban planning and transportation development. However, due to the confusion of spectral characteristic, it is difficult to distinguish roads from other objects by merely using traditional classification methods that mainly depend on spectral information. Edge is an important feature for the identification of linear objects (e. g. , roads). The distribution patterns of edges vary greatly among different objects. It is crucial to merge edge statistical information into spectral ones. In this study, a new method that combines spectral information and edge statistical features has been proposed. First, edge detection is conducted by using self-adaptive mean-shift algorithm on the panchromatic band, which can greatly reduce pseudo-edges and noise effects. Then, edge statistical features are obtained from the edge statistical model, which measures the length and angle distribution of edges. Finally, by integrating the spectral and edge statistical features, SVM algorithm is used to classify the image and roads are ultimately extracted. A series of experiments are conducted and the results show that the overall accuracy of proposed method is 93% comparing with only 78% overall accuracy of the traditional. The results demonstrate that the proposed method is efficient and valuable for road extraction, especially on high-resolution images.

  9. A New Method for Computed Tomography Angiography (CTA) Imaging via Wavelet Decomposition-Dependented Edge Matching Interpolation.

    PubMed

    Li, Zeyu; Chen, Yimin; Zhao, Yan; Zhu, Lifeng; Lv, Shengqing; Lu, Jiahui

    2016-08-01

    The interpolation technique of computed tomography angiography (CTA) image provides the ability for 3D reconstruction, as well as reduces the detect cost and the amount of radiation. However, most of the image interpolation algorithms cannot take the automation and accuracy into account. This study provides a new edge matching interpolation algorithm based on wavelet decomposition of CTA. It includes mark, scale and calculation (MSC). Combining the real clinical image data, this study mainly introduces how to search for proportional factor and use the root mean square operator to find a mean value. Furthermore, we re- synthesize the high frequency and low frequency parts of the processed image by wavelet inverse operation, and get the final interpolation image. MSC can make up for the shortage of the conventional Computed Tomography (CT) and Magnetic Resonance Imaging(MRI) examination. The radiation absorption and the time to check through the proposed synthesized image were significantly reduced. In clinical application, it can help doctor to find hidden lesions in time. Simultaneously, the patients get less economic burden as well as less radiation exposure absorbed.

  10. 3CCD image segmentation and edge detection based on MATLAB

    NASA Astrophysics Data System (ADS)

    He, Yong; Pan, Jiazhi; Zhang, Yun

    2006-09-01

    This research aimed to identify weeds from crops in early stage in the field operation by using image-processing technology. As 3CCD images offer greater binary value difference between weed and crop section than ordinary digital images taken by common cameras. It has 3 channels (green, red, ifred) which takes a snap-photo of the same area, and the three images can be composed into one image, which facilitates the segmentation of different areas. By the application of image-processing toolkit on MATLAB, the different areas in the image can be segmented clearly. As edge detection technique is the first and very important step in image processing, The different result of different processing method was compared. Especially, by using the wavelet packet transform toolkit on MATLAB, An image was preprocessed and then the edge was extracted, and getting more clearly cut image of edge. The segmentation methods include operations as erosion, dilation and other algorithms to preprocess the images. It is of great importance to segment different areas in digital images in field real time, so as to be applied in precision farming, to saving energy and herbicide and many other materials. At present time Large scale software as MATLAB on PC was used, but the computation can be reduced and integrated into a small embed system, which means that the application of this technique in agricultural engineering is feasible and of great economical value.

  11. Application toward Confocal Full-Field Microscopic X-ray Absorption Near Edge Structure Spectroscopy.

    PubMed

    Tack, Pieter; Vekemans, Bart; Laforce, Brecht; Rudloff-Grund, Jennifer; Hernández, Willinton Y; Garrevoet, Jan; Falkenberg, Gerald; Brenker, Frank; Van Der Voort, Pascal; Vincze, Laszlo

    2017-02-07

    Using X-ray absorption near edge structure (XANES) spectroscopy, information on the local chemical structure and oxidation state of an element of interest can be acquired. Conventionally, this information can be obtained in a spatially resolved manner by scanning a sample through a focused X-ray beam. Recently, full-field methods have been developed to obtain direct 2D chemical state information by imaging a large sample area. These methods are usually in transmission mode, thus restricting the use to thin and transmitting samples. Here, a fluorescence method is displayed using an energy-dispersive pnCCD detector, the SLcam, characterized by measurement times far superior to what is generally applicable. Additionally, this method operates in confocal mode, thus providing direct 3D spatially resolved chemical state information from a selected subvolume of a sample, without the need of rotating a sample. The method is applied to two samples: a gold-supported magnesia catalyst (Au/MgO) and a natural diamond containing Fe-rich inclusions. Both samples provide XANES spectra that can be overlapped with reference XANES spectra, allowing this method to be used for fingerprinting and linear combination analysis of known XANES reference compounds.

  12. Long-Range Chemical Sensitivity in the Sulfur K-Edge X-ray Absorption Spectra of Substituted Thiophenes

    PubMed Central

    2015-01-01

    Thiophenes are the simplest aromatic sulfur-containing compounds and are stable and widespread in fossil fuels. Regulation of sulfur levels in fuels and emissions has become and continues to be ever more stringent as part of governments’ efforts to address negative environmental impacts of sulfur dioxide. In turn, more effective removal methods are continually being sought. In a chemical sense, thiophenes are somewhat obdurate and hence their removal from fossil fuels poses problems for the industrial chemist. Sulfur K-edge X-ray absorption spectroscopy provides key information on thiophenic components in fuels. Here we present a systematic study of the spectroscopic sensitivity to chemical modifications of the thiophene system. We conclude that while the utility of sulfur K-edge X-ray absorption spectra in understanding the chemical composition of sulfur-containing fossil fuels has already been demonstrated, care must be exercised in interpreting these spectra because the assumption of an invariant spectrum for thiophenic forms may not always be valid. PMID:25116792

  13. Temperature dependence of the Urbach optical absorption edge: A theory of multiple phonon absorption and emission sidebands

    NASA Astrophysics Data System (ADS)

    Grein, C. H.; John, Sajeev

    1989-01-01

    The optical absorption coefficient for subgap electronic transitions in crystalline and disordered semiconductors is calculated by first-principles means with use of a variational principle based on the Feynman path-integral representation of the transition amplitude. This incorporates the synergetic interplay of static disorder and the nonadiabatic quantum dynamics of the coupled electron-phonon system. Over photon-energy ranges of experimental interest, this method predicts accurate linear exponential Urbach behavior of the absorption coefficient. At finite temperatures the nonlinear electron-phonon interaction gives rise to multiple phonon emission and absorption sidebands which accompany the optically induced electronic transition. These sidebands dominate the absorption in the Urbach regime and account for the temperature dependence of the Urbach slope and energy gap. The physical picture which emerges is that the phonons absorbed from the heat bath are then reemitted into a dynamical polaronlike potential well which localizes the electron. At zero temperature we recover the usual polaron theory. At high temperatures the calculated tail is qualitatively similar to that of a static Gaussian random potential. This leads to a linear relationship between the Urbach slope and the downshift of the extrapolated continuum band edge as well as a temperature-independent Urbach focus. At very low temperatures, deviations from these rules are predicted arising from the true quantum dynamics of the lattice. Excellent agreement is found with experimental data on c-Si, a-Si:H, a-As2Se3, and a-As2S3. Results are compared with a simple physical argument based on the most-probable-potential-well method.

  14. Infrared study of the absorption edge of {beta}-InN films grown on GaN/MgO structures

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Perez-Caro, M.; Rodriguez, A. G.; Vidal, M. A.

    2010-07-15

    Infrared optical studies were carried out in a group of cubic InN samples grown by gas source molecular beam epitaxy on MgO (001) substrates. Room temperature (RT) reflectance and low-temperature (LT) transmittance measurements were performed by using fast Fourier transform infrared spectrometry. Reflectance fittings allowed to establish that {beta}-InN films have large free-carrier concentrations present (>10{sup 19} cm{sup -3}), a result that is corroborated by Hall effect measurements. Each sample explored exhibited a different optical absorption edge. The Varshni parameters that describe adequately the optical absorption edge responses with temperature are obtained for the set of samples studied. The observedmore » temperatures changes, from LT to RT, are the lowest reported for III-V semiconductor binary compounds. The temperature coefficient of the conduction band depends on the strength of the electron-phonon interaction (e-ph-i), as well as on the thermal expansion. It has been predicted that cubic InN has one of the smallest e-ph-i of all III-V compounds, which is corroborated by these results. The variation in values of absorption edges is clearly consistent with the Burstein-Moss and band renormalization effects, produced by high free electron concentrations. It is shown that the conduction band in {beta}-InN, analogous to wurtzite InN, follows a nonparabolic behavior.« less

  15. Infrared study of the absorption edge of β-InN films grown on GaN/MgO structures

    NASA Astrophysics Data System (ADS)

    Pérez-Caro, M.; Rodríguez, A. G.; Vidal, M. A.; Navarro-Contreras, H.

    2010-07-01

    Infrared optical studies were carried out in a group of cubic InN samples grown by gas source molecular beam epitaxy on MgO (001) substrates. Room temperature (RT) reflectance and low-temperature (LT) transmittance measurements were performed by using fast Fourier transform infrared spectrometry. Reflectance fittings allowed to establish that β-InN films have large free-carrier concentrations present (>1019 cm-3), a result that is corroborated by Hall effect measurements. Each sample explored exhibited a different optical absorption edge. The Varshni parameters that describe adequately the optical absorption edge responses with temperature are obtained for the set of samples studied. The observed temperatures changes, from LT to RT, are the lowest reported for III-V semiconductor binary compounds. The temperature coefficient of the conduction band depends on the strength of the electron-phonon interaction (e-ph-i), as well as on the thermal expansion. It has been predicted that cubic InN has one of the smallest e-ph-i of all III-V compounds, which is corroborated by these results. The variation in values of absorption edges is clearly consistent with the Burstein-Moss and band renormalization effects, produced by high free electron concentrations. It is shown that the conduction band in β-InN, analogous to wurtzite InN, follows a nonparabolic behavior.

  16. [An object-oriented remote sensing image segmentation approach based on edge detection].

    PubMed

    Tan, Yu-Min; Huai, Jian-Zhu; Tang, Zhong-Shi

    2010-06-01

    Satellite sensor technology endorsed better discrimination of various landscape objects. Image segmentation approaches to extracting conceptual objects and patterns hence have been explored and a wide variety of such algorithms abound. To this end, in order to effectively utilize edge and topological information in high resolution remote sensing imagery, an object-oriented algorithm combining edge detection and region merging is proposed. Susan edge filter is firstly applied to the panchromatic band of Quickbird imagery with spatial resolution of 0.61 m to obtain the edge map. Thanks to the resulting edge map, a two-phrase region-based segmentation method operates on the fusion image from panchromatic and multispectral Quickbird images to get the final partition result. In the first phase, a quad tree grid consisting of squares with sides parallel to the image left and top borders agglomerates the square subsets recursively where the uniform measure is satisfied to derive image object primitives. Before the merger of the second phrase, the contextual and spatial information, (e. g., neighbor relationship, boundary coding) of the resulting squares are retrieved efficiently by means of the quad tree structure. Then a region merging operation is performed with those primitives, during which the criterion for region merging integrates edge map and region-based features. This approach has been tested on the QuickBird images of some site in Sanxia area and the result is compared with those of ENVI Zoom Definiens. In addition, quantitative evaluation of the quality of segmentation results is also presented. Experiment results demonstrate stable convergence and efficiency.

  17. Backscatter absorption gas imaging system

    DOEpatents

    McRae, Jr., Thomas G.

    1985-01-01

    A video imaging system for detecting hazardous gas leaks. Visual displays of invisible gas clouds are produced by radiation augmentation of the field of view of an imaging device by radiation corresponding to an absorption line of the gas to be detected. The field of view of an imager is irradiated by a laser. The imager receives both backscattered laser light and background radiation. When a detectable gas is present, the backscattered laser light is highly attenuated, producing a region of contrast or shadow on the image. A flying spot imaging system is utilized to synchronously irradiate and scan the area to lower laser power requirements. The imager signal is processed to produce a video display.

  18. Backscatter absorption gas imaging system

    DOEpatents

    McRae, T.G. Jr.

    A video imaging system for detecting hazardous gas leaks. Visual displays of invisible gas clouds are produced by radiation augmentation of the field of view of an imaging device by radiation corresponding to an absorption line of the gas to be detected. The field of view of an imager is irradiated by a laser. The imager receives both backscattered laser light and background radiation. When a detectable gas is present, the backscattered laser light is highly attenuated, producing a region of contrast or shadow on the image. A flying spot imaging system is utilized to synchronously irradiate and scan the area to lower laser power requirements. The imager signal is processed to produce a video display.

  19. High-Resolution Imaging of the Multiphase Interstellar Thick Disk in Two Edge-On Spiral Galaxies

    NASA Astrophysics Data System (ADS)

    Howk, J. Christopher; Rueff, K.

    2009-01-01

    We present broadband and narrow-band images, acquired from Hubble Space Telescope WFPC2 and WIYN 3.5 m telescope respectively, of two edge-on spiral galaxies, NGC 4302 and NGC 4013. These high-resolution images (BVI + H-alpha) provide a detailed view of the thick disk interstellar medium (ISM) in these galaxies. Both galaxies show prominent extraplanar dust-bearing clouds viewed in absorption against the background stellar light. Individual clouds are found to z 2 kpc in each galaxy. These clouds each contain >10^4 to >10^5 solar masses of gas. Both galaxies have extraplanar diffuse ionized gas (DIG), as seen in our H-alpha images and earlier work. In addition to the DIG, discrete H II regions are found at heights up to 1 kpc from both galaxies. We compare the morphologies of the dusty clouds with the DIG in these galaxies and discuss the relationship between these components of the thick disk ISM.

  20. Mass attenuation coefficient of chromium and manganese compounds around absorption edge.

    PubMed

    Sharanabasappa; Kaginelli, S B; Kerur, B R; Anilkumar, S; Hanumaiah, B

    2009-01-01

    The total mass attenuation coefficient for Potassium dichromate, Potassium chromate and Manganese acetate compounds are measured at different photon energies 5.895, 6.404, 6.490, 7.058, 8.041 and 14.390 keV using Fe-55, Co-57 and 241Am source with Copper target, radioactive sources. The photon intensity is analyzed using a high resolution HPGe detector system coupled to MCA under good geometrical arrangement. The obtained values of mass attenuation coefficient values are compared with theoretical values. This study suggests that measured mass attenuation coefficient values at and near absorption edges differ from the theoretical value by about 5-28%.

  1. Effects of acoustic- and optical-phonon sidebands on the fundamental optical-absorption edge in crystals and disordered semiconductors

    NASA Astrophysics Data System (ADS)

    Grein, C. H.; John, Sajeev

    1990-04-01

    We present the results of a parameter-free first-principles theory for the fine structure of the Urbach optical-absorption edge in crystalline and disordered semiconductors. The dominant features are recaptured by means of a simple physical argument based on the most probable potential-well analogy. At finite temperatures, the overall linear exponential Urbach behavior of the subgap optical-absorption coefficient is a consequence of multiple LA-phonon emission and absorption sidebands that accompany the electronic transition. The fine structure of subgap absorption spectra observed in some materials is accounted for by multiple TO-, LO-, and TA-phonon absorption and emission sidebands. Good agreement is found with experimental data on crystalline silicon. The effects of nonadiabaticity in the electron-phonon interaction are calculated.

  2. Helium ion microscopy of graphene: beam damage, image quality and edge contrast

    NASA Astrophysics Data System (ADS)

    Fox, D.; Zhou, Y. B.; O'Neill, A.; Kumar, S.; Wang, J. J.; Coleman, J. N.; Duesberg, G. S.; Donegan, J. F.; Zhang, H. Z.

    2013-08-01

    A study to analyse beam damage, image quality and edge contrast in the helium ion microscope (HIM) has been undertaken. The sample investigated was graphene. Raman spectroscopy was used to quantify the disorder that can be introduced into the graphene as a function of helium ion dose. The effects of the dose on both freestanding and supported graphene were compared. These doses were then correlated directly to image quality by imaging graphene flakes at high magnification. It was found that a high magnification image with a good signal to noise ratio will introduce very significant sample damage. A safe imaging dose of the order of 1013 He+ cm-2 was established, with both graphene samples becoming highly defective at doses over 5 × 1014 He+ cm-2. The edge contrast of a freestanding graphene flake imaged in the HIM was then compared with the contrast of the same flake observed in a scanning electron microscope and a transmission electron microscope. Very strong edge sensitivity was observed in the HIM. This enhanced edge sensitivity over the other techniques investigated makes the HIM a powerful nanoscale dimensional metrology tool, with the capability of both fabricating and imaging features with sub-nanometre resolution.

  3. Blurred image restoration using knife-edge function and optimal window Wiener filtering.

    PubMed

    Wang, Min; Zhou, Shudao; Yan, Wei

    2018-01-01

    Motion blur in images is usually modeled as the convolution of a point spread function (PSF) and the original image represented as pixel intensities. The knife-edge function can be used to model various types of motion-blurs, and hence it allows for the construction of a PSF and accurate estimation of the degradation function without knowledge of the specific degradation model. This paper addresses the problem of image restoration using a knife-edge function and optimal window Wiener filtering. In the proposed method, we first calculate the motion-blur parameters and construct the optimal window. Then, we use the detected knife-edge function to obtain the system degradation function. Finally, we perform Wiener filtering to obtain the restored image. Experiments show that the restored image has improved resolution and contrast parameters with clear details and no discernible ringing effects.

  4. Blurred image restoration using knife-edge function and optimal window Wiener filtering

    PubMed Central

    Zhou, Shudao; Yan, Wei

    2018-01-01

    Motion blur in images is usually modeled as the convolution of a point spread function (PSF) and the original image represented as pixel intensities. The knife-edge function can be used to model various types of motion-blurs, and hence it allows for the construction of a PSF and accurate estimation of the degradation function without knowledge of the specific degradation model. This paper addresses the problem of image restoration using a knife-edge function and optimal window Wiener filtering. In the proposed method, we first calculate the motion-blur parameters and construct the optimal window. Then, we use the detected knife-edge function to obtain the system degradation function. Finally, we perform Wiener filtering to obtain the restored image. Experiments show that the restored image has improved resolution and contrast parameters with clear details and no discernible ringing effects. PMID:29377950

  5. Edge-preserving image compression for magnetic-resonance images using dynamic associative neural networks (DANN)-based neural networks

    NASA Astrophysics Data System (ADS)

    Wan, Tat C.; Kabuka, Mansur R.

    1994-05-01

    With the tremendous growth in imaging applications and the development of filmless radiology, the need for compression techniques that can achieve high compression ratios with user specified distortion rates becomes necessary. Boundaries and edges in the tissue structures are vital for detection of lesions and tumors, which in turn requires the preservation of edges in the image. The proposed edge preserving image compressor (EPIC) combines lossless compression of edges with neural network compression techniques based on dynamic associative neural networks (DANN), to provide high compression ratios with user specified distortion rates in an adaptive compression system well-suited to parallel implementations. Improvements to DANN-based training through the use of a variance classifier for controlling a bank of neural networks speed convergence and allow the use of higher compression ratios for `simple' patterns. The adaptation and generalization capabilities inherent in EPIC also facilitate progressive transmission of images through varying the number of quantization levels used to represent compressed patterns. Average compression ratios of 7.51:1 with an averaged average mean squared error of 0.0147 were achieved.

  6. Studies by Near Edge X-ray Absorption Spectroscopies of Bonding Dynamics at the Graphene/Guanine Interface - A Proposal for High Mobility, Organic Graphene Field Effect Transistors

    DTIC Science & Technology

    2015-07-01

    AFRL-AFOSR-UK-TR-2015-0034 Studies by Near Edge X-ray Absorption Spectroscopies of Bonding Dynamics at the Graphene /Guanine...Interface – A Proposal for High Mobility, Organic Graphene Field Effect Transistors Eva Campo BANGOR UNIVERSITY COLLEGE ROAD BANGOR...April 2015 4. TITLE AND SUBTITLE Studies by Near Edge X-ray Absorption Spectroscopies of Bonding Dynamics at the Graphene /Guanine Interface - A

  7. A high pressure La K-edge X-ray absorption fine structure spectroscopy investigation of La1/3NbO3

    NASA Astrophysics Data System (ADS)

    Marini, C.; Joseph, B.; Noked, O.; Shuker, R.; Kennedy, B. J.; Mathon, O.; Pascarelli, S.; Sterer, E.

    2018-01-01

    La K-edge X-ray absorption spectroscopy has been used to elucidate the changes in the local electronic and lattice structure that occur in the A-site deficient double perovskite La?NbO? up to 6 GPa. The pressure evolution of the oxygen dodecahedrum around the A-site has been examined. XANES (X-ray absorption near edge structure) data show modifications ascribed to the increase of bands overlapping as a consequence of the bond distance contraction, which has been directly probed by EXAFS (extended x-ray absorption fine structure) spectra. The La-O Debye Waller factors (DWFs) tend to increase whereas the La-Nb bond DWFs show only a tendency to decrease indicating the robustness of the crystal lattice structure, even in presence of the oxygen disordering. This permits the system to reverse back to its original conditions in this pressure range as evident from the measurements upon pressure release. The present results have been interpreted in the light of charge transfer related to the two-step reduction mechanism acting at the Nb site (with niobium ions passing from Nb? to Nb?) which also results in the elongation of the Nb-O bond distances in the octahedra, in agreement with the Nb K-edge results reported earlier.

  8. Interaction of Nanostructured Calcium Silicate Hydrate with Ibuprofen Drug Molecules: X-ray Absorption Near Edge Structure (XANES) Study at the Ca, Si and O K-edge

    NASA Astrophysics Data System (ADS)

    Guo, X. X.; Sham, T. K.; Zhu, Y. J.; Hu, Y. F.

    2013-04-01

    Mesoporous calcium silicate hydrate (CSH) nanostructure has been proven to be bioactive and biocompatible, and has a bright future in the application of bone treatment among other applications. X-ray absorption near edge structure (XANES) is a powerful tool for the study of the interactions of calcium silicate hydrates with drug molecules because it is element specific and it probes the unoccupied electronic states. Herein, we report the use of the calcium, silicon and oxygen K-edge XANES spectroscopy to identify how drug molecules interact with different groups in calcium silicate hydrate mesoporous nano-carriers with different morphologies. Significant changes are observed in XANES spectra after drug loading into the calcium silicate hydrate system, especially at the Si and O K-edge. The implications of these findings are discussed.

  9. Accelerated Edge-Preserving Image Restoration Without Boundary Artifacts

    PubMed Central

    Matakos, Antonios; Ramani, Sathish; Fessler, Jeffrey A.

    2013-01-01

    To reduce blur in noisy images, regularized image restoration methods have been proposed that use non-quadratic regularizers (like l1 regularization or total-variation) that suppress noise while preserving edges in the image. Most of these methods assume a circulant blur (periodic convolution with a blurring kernel) that can lead to wraparound artifacts along the boundaries of the image due to the implied periodicity of the circulant model. Using a non-circulant model could prevent these artifacts at the cost of increased computational complexity. In this work we propose to use a circulant blur model combined with a masking operator that prevents wraparound artifacts. The resulting model is non-circulant, so we propose an efficient algorithm using variable splitting and augmented Lagrangian (AL) strategies. Our variable splitting scheme, when combined with the AL framework and alternating minimization, leads to simple linear systems that can be solved non-iteratively using FFTs, eliminating the need for more expensive CG-type solvers. The proposed method can also efficiently tackle a variety of convex regularizers including edge-preserving (e.g., total-variation) and sparsity promoting (e.g., l1 norm) regularizers. Simulation results show fast convergence of the proposed method, along with improved image quality at the boundaries where the circulant model is inaccurate. PMID:23372080

  10. Theoretical X-ray production cross sections at incident photon energies across Li (i=1-3) absorption edges of Br

    NASA Astrophysics Data System (ADS)

    Puri, Sanjiv

    2015-08-01

    The X-ray production (XRP) cross sections, σLk (k = l, η, α, β6, β1, β3, β4, β9,10, γ1,5, γ2,3) have been evaluated at incident photon energies across the Li(i=1-3) absorption edge energies of 35Br using theoretical data sets of different physical parameters, namely, the Li(i=1-3) sub-shell the X-ray emission rates based on the Dirac-Fock (DF) model, the fluorescence and Coster Kronig yields based on the Dirac-Hartree-Slater (DHS) model, and two sets of the photoionisation cross sections based on the relativistic Hartree-Fock-Slater (RHFS) model and the Dirac-Fock (DF) model, in order to highlight the importance of electron exchange effects at photon energies in vicinity of absorption edge energies.

  11. Influence of defects on the absorption edge of InN thin films: The band gap value

    NASA Astrophysics Data System (ADS)

    Thakur, J. S.; Danylyuk, Y. V.; Haddad, D.; Naik, V. M.; Naik, R.; Auner, G. W.

    2007-07-01

    We investigate the optical-absorption spectra of InN thin films whose electron density varies from ˜1017tõ1021cm-3 . The low-density films are grown by molecular-beam-epitaxy deposition while highly degenerate films are grown by plasma-source molecular-beam epitaxy. The optical-absorption edge is found to increase from 0.61to1.90eV as the carrier density of the films is increased from low to high density. Since films are polycrystalline and contain various types of defects, we discuss the band gap values by studying the influence of electron degeneracy, electron-electron, electron-ionized impurities, and electron-LO-phonon interaction self-energies on the spectral absorption coefficients of these films. The quasiparticle self-energies of the valence and conduction bands are calculated using dielectric screening within the random-phase approximation. Using one-particle Green’s function analysis, we self-consistently determine the chemical potential for films by coupling equations for the chemical potential and the single-particle scattering rate calculated within the effective-mass approximation for the electron scatterings from ionized impurities and LO phonons. By subtracting the influence of self-energies and chemical potential from the optical-absorption edge energy, we estimate the intrinsic band gap values for the films. We also determine the variations in the calculated band gap values due to the variations in the electron effective mass and static dielectric constant. For the lowest-density film, the estimated band gap energy is ˜0.59eV , while for the highest-density film, it varies from ˜0.60tõ0.68eV depending on the values of electron effective mass and dielectric constant.

  12. A robust sub-pixel edge detection method of infrared image based on tremor-based retinal receptive field model

    NASA Astrophysics Data System (ADS)

    Gao, Kun; Yang, Hu; Chen, Xiaomei; Ni, Guoqiang

    2008-03-01

    Because of complex thermal objects in an infrared image, the prevalent image edge detection operators are often suitable for a certain scene and extract too wide edges sometimes. From a biological point of view, the image edge detection operators work reliably when assuming a convolution-based receptive field architecture. A DoG (Difference-of- Gaussians) model filter based on ON-center retinal ganglion cell receptive field architecture with artificial eye tremors introduced is proposed for the image contour detection. Aiming at the blurred edges of an infrared image, the subsequent orthogonal polynomial interpolation and sub-pixel level edge detection in rough edge pixel neighborhood is adopted to locate the foregoing rough edges in sub-pixel level. Numerical simulations show that this method can locate the target edge accurately and robustly.

  13. Synthetic Aperture Microwave Imaging (SAMI) of the plasma edge on NSTX-U

    NASA Astrophysics Data System (ADS)

    Vann, Roddy; Taylor, Gary; Brunner, Jakob; Ellis, Bob; Thomas, David

    2016-10-01

    The Synthetic Aperture Microwave Imaging (SAMI) system is a unique phased-array microwave camera with a +/-40° field of view in both directions. It can image cut-off surfaces corresponding to frequencies in the range 10-34.5GHz; these surfaces are typically in the plasma edge. SAMI operates in two modes: either imaging thermal emission from the plasma (often modified by its interaction with the plasma edge e.g. via BXO mode conversion) or ``active probing'' i.e. injecting a broad beam at the plasma surface and imaging the reflected/back-scattered signal. SAMI was successfully pioneered on the Mega-Amp Spherical Tokamak (MAST) at Culham Centre for Fusion Energy. SAMI has now been installed and commissioned on the National Spherical Torus Experiment Upgrade (NSTX-U) at Princeton Plasma Physics Laboratory. The firmware has been upgraded to include real-time digital filtering, which enables continuous acquisition of the Doppler back-scattered active probing data. In this poster we shall present SAMI's analysis of the plasma edge on NSTX-U including measurements of the edge pitch angle on NSTX-U using SAMI's unique 2-D Doppler-backscattering capability.

  14. Image-Data Compression Using Edge-Optimizing Algorithm for WFA Inference.

    ERIC Educational Resources Information Center

    Culik, Karel II; Kari, Jarkko

    1994-01-01

    Presents an inference algorithm that produces a weighted finite automata (WFA), in particular, the grayness functions of graytone images. Image-data compression results based on the new inference algorithm produces a WFA with a relatively small number of edges. Image-data compression results alone and in combination with wavelets are discussed.…

  15. X-ray absorption near edge structure/electron energy loss near edge structure calculation using the supercell orthogonalized linear combination of atomic orbitals method

    NASA Astrophysics Data System (ADS)

    Ching, Wai-Yim; Rulis, Paul

    2009-03-01

    Over the last eight years, a large number of x-ray absorption near edge structure (XANES) and/or electron energy loss near edge structure (ELNES) spectroscopic calculations for complex oxides and nitrides have been performed using the supercell-OLCAO (orthogonalized linear combination of atomic orbitals) method, obtaining results in very good agreement with experiments. The method takes into account the core-hole effect and includes the dipole matrix elements calculated from ab initio wavefunctions. In this paper, we describe the method in considerable detail, emphasizing the special advantages of this method for large complex systems. Selected results are reviewed and several hitherto unpublished results are also presented. These include the Y K edge of Y ions segregated to the core of a Σ31 grain boundary in alumina, O K edges of water molecules, C K edges in different types of single walled carbon nanotubes, and the Co K edge in the cyanocobalamin (vitamin B12) molecule. On the basis of these results, it is argued that the interpretation of specific features of the calculated XANES/ELNES edges is not simple for complex material systems because of the delocalized nature of the conduction band states. The long-standing notion of the 'fingerprinting' technique for spectral interpretation of experimental data is not tenable. A better approach is to fully characterize the structure under study, using either crystalline data or accurate ab initio modeling. Comparison between calculated XANES/ELNES spectra and available measurements enables us to ascertain the validity of the modeled structure. For complex crystals or structures, it is necessary to use the weighted sum of the spectra from structurally nonequivalent sites for comparison with the measured data. Future application of the supercell-OLCAO method to complex biomolecular systems is also discussed.

  16. Surface stress mediated image force and torque on an edge dislocation

    NASA Astrophysics Data System (ADS)

    Raghavendra, R. M.; Divya, Iyer, Ganesh; Kumar, Arun; Subramaniam, Anandh

    2018-07-01

    The proximity of interfaces gives prominence to image forces experienced by dislocations. The presence of surface stress alters the traction-free boundary conditions existing on free-surfaces and hence is expected to alter the magnitude of the image force. In the current work, using a combined simulation of surface stress and an edge dislocation in a semi-infinite body, we evaluate the configurational effects on the system. We demonstrate that if the extra half-plane of the edge dislocation is parallel to the surface, the image force (glide) is not altered due to surface stress; however, the dislocation experiences a torque. The surface stress breaks the 'climb image force' symmetry, thus leading to non-equivalence between positive and negative climb. We discover an equilibrium position for the edge dislocation in the positive 'climb geometry', arising due to a competition between the interaction of the dislocation stress fields with the surface stress and the image dislocation. Torque in the climb configuration is not affected by surface stress (remains zero). Surface stress is computed using a recently developed two-scale model based on Shuttleworth's idea and image forces using a finite element model developed earlier. The effect of surface stress on the image force and torque experienced by the dislocation monopole is analysed using illustrative 3D models.

  17. Determination of optical absorption coefficient with focusing photoacoustic imaging.

    PubMed

    Li, Zhifang; Li, Hui; Zeng, Zhiping; Xie, Wenming; Chen, Wei R

    2012-06-01

    Absorption coefficient of biological tissue is an important factor for photothermal therapy and photoacoustic imaging. However, its determination remains a challenge. In this paper, we propose a method using focusing photoacoustic imaging technique to quantify the target optical absorption coefficient. It utilizes the ratio of the amplitude of the peak signal from the top boundary of the target to that from the bottom boundary based on wavelet transform. This method is self-calibrating. Factors, such as absolute optical fluence, ultrasound parameters, and Grüneisen parameter, can be canceled by dividing the amplitudes of the two peaks. To demonstrate this method, we quantified the optical absorption coefficient of a target with various concentrations of an absorbing dye. This method is particularly useful to provide accurate absorption coefficient for predicting the outcomes of photothermal interaction for cancer treatment with absorption enhancement.

  18. Transition metal atomic multiplets in the ligand K-edge x-ray absorption spectra and multiple oxidation states in the L2,3 emission of strongly correlated compounds

    NASA Astrophysics Data System (ADS)

    Jiménez-Mier, J.; Olalde-Velasco, P.; Yang, W.-L.; Denlinger, J.

    2014-07-01

    We present results that show that atomic multiplet ligand field calculations are in very good agreement with experimental x-ray absorption spectra at the L2,3 edge of transition metal (TM) di-fluorides (MF2, MCrCu). For chromium more than one TM oxidation state is needed to achieve such an agreement. We also show that signature of the TM atomic multiplet can be found at the pre-edge of the fluorine K-edge x-ray absorption spectra. TM atomic multiplet ligand field calculations with a structureless core hole show good agreement with the observed pre-edges in the experimental fluorine absorption spectra. Preliminary results for the comparison between calculated and experimental resonant x-ray emission spectra for nominal CrF2 with more than one oxidation state indicate the presence of three chromium oxidation states in the bulk.

  19. Edge guided image reconstruction in linear scan CT by weighted alternating direction TV minimization.

    PubMed

    Cai, Ailong; Wang, Linyuan; Zhang, Hanming; Yan, Bin; Li, Lei; Xi, Xiaoqi; Li, Jianxin

    2014-01-01

    Linear scan computed tomography (CT) is a promising imaging configuration with high scanning efficiency while the data set is under-sampled and angularly limited for which high quality image reconstruction is challenging. In this work, an edge guided total variation minimization reconstruction (EGTVM) algorithm is developed in dealing with this problem. The proposed method is modeled on the combination of total variation (TV) regularization and iterative edge detection strategy. In the proposed method, the edge weights of intermediate reconstructions are incorporated into the TV objective function. The optimization is efficiently solved by applying alternating direction method of multipliers. A prudential and conservative edge detection strategy proposed in this paper can obtain the true edges while restricting the errors within an acceptable degree. Based on the comparison on both simulation studies and real CT data set reconstructions, EGTVM provides comparable or even better quality compared to the non-edge guided reconstruction and adaptive steepest descent-projection onto convex sets method. With the utilization of weighted alternating direction TV minimization and edge detection, EGTVM achieves fast and robust convergence and reconstructs high quality image when applied in linear scan CT with under-sampled data set.

  20. Optimizing Robinson Operator with Ant Colony Optimization As a Digital Image Edge Detection Method

    NASA Astrophysics Data System (ADS)

    Yanti Nasution, Tarida; Zarlis, Muhammad; K. M Nasution, Mahyuddin

    2017-12-01

    Edge detection serves to identify the boundaries of an object against a background of mutual overlap. One of the classic method for edge detection is operator Robinson. Operator Robinson produces a thin, not assertive and grey line edge. To overcome these deficiencies, the proposed improvements to edge detection method with the approach graph with Ant Colony Optimization algorithm. The repairs may be performed are thicken the edge and connect the edges cut off. Edge detection research aims to do optimization of operator Robinson with Ant Colony Optimization then compare the output and generated the inferred extent of Ant Colony Optimization can improve result of edge detection that has not been optimized and improve the accuracy of the results of Robinson edge detection. The parameters used in performance measurement of edge detection are morphology of the resulting edge line, MSE and PSNR. The result showed that Robinson and Ant Colony Optimization method produces images with a more assertive and thick edge. Ant Colony Optimization method is able to be used as a method for optimizing operator Robinson by improving the image result of Robinson detection average 16.77 % than classic Robinson result.

  1. Identification of F impurities in F-doped ZnO by synchrotron X-ray absorption near edge structures

    NASA Astrophysics Data System (ADS)

    Na-Phattalung, Sutassana; Limpijumnong, Sukit; Min, Chul-Hee; Cho, Deok-Yong; Lee, Seung-Ran; Char, Kookrin; Yu, Jaejun

    2018-04-01

    Synchrotron X-ray absorption near edge structure (XANES) measurements of F K-edge in conjunction with first-principles calculations are used to identify the local structure of the fluorine (F) atom in F-doped ZnO. The ZnO film was grown by pulsed laser deposition with an Nd:YAG laser, and an oxyfluoridation method was used to introduce F ions into the ZnO films. The measured XANES spectrum of the sample was compared against the first-principles XANES calculations based on various models for local atomic structures surrounding F atoms. The observed spectral features are attributed to ZnF2 and FO defects in wurtzite bulk ZnO.

  2. Soft X-ray absorption spectroscopy and resonant inelastic X-ray scattering spectroscopy below 100 eV: probing first-row transition-metal M-edges in chemical complexes.

    PubMed

    Wang, Hongxin; Young, Anthony T; Guo, Jinghua; Cramer, Stephen P; Friedrich, Stephan; Braun, Artur; Gu, Weiwei

    2013-07-01

    X-ray absorption and scattering spectroscopies involving the 3d transition-metal K- and L-edges have a long history in studying inorganic and bioinorganic molecules. However, there have been very few studies using the M-edges, which are below 100 eV. Synchrotron-based X-ray sources can have higher energy resolution at M-edges. M-edge X-ray absorption spectroscopy (XAS) and resonant inelastic X-ray scattering (RIXS) could therefore provide complementary information to K- and L-edge spectroscopies. In this study, M2,3-edge XAS on several Co, Ni and Cu complexes are measured and their spectral information, such as chemical shifts and covalency effects, are analyzed and discussed. In addition, M2,3-edge RIXS on NiO, NiF2 and two other covalent complexes have been performed and different d-d transition patterns have been observed. Although still preliminary, this work on 3d metal complexes demonstrates the potential to use M-edge XAS and RIXS on more complicated 3d metal complexes in the future. The potential for using high-sensitivity and high-resolution superconducting tunnel junction X-ray detectors below 100 eV is also illustrated and discussed.

  3. Reduced chromium in olivine grains from lunar basalt 15555 - X-ray Absorption Near Edge Structure (XANES)

    NASA Technical Reports Server (NTRS)

    Sutton, S. R.; Jones, K. W.; Gordon, B.; Rivers, M. L.; Bajt, S.; Smith, J. V.

    1993-01-01

    The oxidation state of Cr in 200-micron regions within individual lunar olivine and pyroxene grains from lunar basalt 15555 was inferred using X-ray Absorption Near Edge Structure (XANES). Reference materials had previously been studied by optical absorption spectroscopy and included Cr-bearing borosilicate glasses synthesized under controlled oxygen fugacity and Cr-doped olivines. The energy dependence of XANES spectral features defined by these reference materials indicated that Cr is predominantly divalent in the lunar olivine and trivalent in the pyroxene. These results, coupled with the apparent f(02)-independence of partitioning coefficients for Cr into olivine, imply that the source magma was dominated by divalent Cr at the time of olivine crystallization.

  4. Face recognition via edge-based Gabor feature representation for plastic surgery-altered images

    NASA Astrophysics Data System (ADS)

    Chude-Olisah, Chollette C.; Sulong, Ghazali; Chude-Okonkwo, Uche A. K.; Hashim, Siti Z. M.

    2014-12-01

    Plastic surgery procedures on the face introduce skin texture variations between images of the same person (intra-subject), thereby making the task of face recognition more difficult than in normal scenario. Usually, in contemporary face recognition systems, the original gray-level face image is used as input to the Gabor descriptor, which translates to encoding some texture properties of the face image. The texture-encoding process significantly degrades the performance of such systems in the case of plastic surgery due to the presence of surgically induced intra-subject variations. Based on the proposition that the shape of significant facial components such as eyes, nose, eyebrow, and mouth remains unchanged after plastic surgery, this paper employs an edge-based Gabor feature representation approach for the recognition of surgically altered face images. We use the edge information, which is dependent on the shapes of the significant facial components, to address the plastic surgery-induced texture variation problems. To ensure that the significant facial components represent useful edge information with little or no false edges, a simple illumination normalization technique is proposed for preprocessing. Gabor wavelet is applied to the edge image to accentuate on the uniqueness of the significant facial components for discriminating among different subjects. The performance of the proposed method is evaluated on the Georgia Tech (GT) and the Labeled Faces in the Wild (LFW) databases with illumination and expression problems, and the plastic surgery database with texture changes. Results show that the proposed edge-based Gabor feature representation approach is robust against plastic surgery-induced face variations amidst expression and illumination problems and outperforms the existing plastic surgery face recognition methods reported in the literature.

  5. Low Z elements (Mg, Al, and Si) K-edge X-ray absorption spectroscopy in minerals and disordered systems

    NASA Astrophysics Data System (ADS)

    Ildefonse, Ph.; Calas, G.; Flank, A. M.; Lagarde, P.

    1995-05-01

    Soft X-ray absorption near edge spectroscopy (XANES) and extended X-ray absorption fine structure (EXAFS) spectroscopy have been performed at the Mg-, Al- and Si-K edges in order to establish the ability of this spectroscopy to derive structural information in disordered solids such as glasses and gels. Mg- and Al-K XANES are good structural probes to determine the coordination state of these elements in important minerals, glasses and gels. In a CaOsbnd MgOsbnd 2SiO2 glass Mg XANES spectra differ from that found in the crystalline equivalent, with a significant shift of the edge maxima to lower energy, consistent with a CN lower than 6. Mg-EXAFS on the same sample are in agreement and indicate the presence of 5-coordinated Mg with Mgsbnd O distances of 2.01Å. In aluminosilicate gels, Alsbnd K XANES has been used to investigate the [4]Al/Altotal ratios. These ratios increase as the Al/Si ratios decrease. Aluminosilicate and ferric-silicate gels were studied by using Sisbnd K edge XANES. XANES spectra differ significantly among the samples studied. Aluminosilicate gels with Al/Si= 1 present a different Al and Si local environment from that known in clay minerals with the same Al/Si ratio. The gel-to-mineral transformation thus implies a dissolution-recrystallization mechanism. On the contrary, ferric-silicate gel presents a Si local environment close to that found in nontronite which may be formed by a long range ordering of the initial gels.

  6. Combining volumetric edge display and multiview display for expression of natural 3D images

    NASA Astrophysics Data System (ADS)

    Yasui, Ryota; Matsuda, Isamu; Kakeya, Hideki

    2006-02-01

    In the present paper the authors present a novel stereoscopic display method combining volumetric edge display technology and multiview display technology to realize presentation of natural 3D images where the viewers do not suffer from contradiction between binocular convergence and focal accommodation of the eyes, which causes eyestrain and sickness. We adopt volumetric display method only for edge drawing, while we adopt stereoscopic approach for flat areas of the image. Since focal accommodation of our eyes is affected only by the edge part of the image, natural focal accommodation can be induced if the edges of the 3D image are drawn on the proper depth. The conventional stereo-matching technique can give us robust depth values of the pixels which constitute noticeable edges. Also occlusion and gloss of the objects can be roughly expressed with the proposed method since we use stereoscopic approach for the flat area. We can attain a system where many users can view natural 3D objects at the consistent position and posture at the same time in this system. A simple optometric experiment using a refractometer suggests that the proposed method can give us 3-D images without contradiction between binocular convergence and focal accommodation.

  7. A Monte Carlo simulation study of an improved K-edge log-subtraction X-ray imaging using a photon counting CdTe detector

    NASA Astrophysics Data System (ADS)

    Lee, Youngjin; Lee, Amy Candy; Kim, Hee-Joung

    2016-09-01

    Recently, significant effort has been spent on the development of photons counting detector (PCD) based on a CdTe for applications in X-ray imaging system. The motivation of developing PCDs is higher image quality. Especially, the K-edge subtraction (KES) imaging technique using a PCD is able to improve image quality and useful for increasing the contrast resolution of a target material by utilizing contrast agent. Based on above-mentioned technique, we presented an idea for an improved K-edge log-subtraction (KELS) imaging technique. The KELS imaging technique based on the PCDs can be realized by using different subtraction energy width of the energy window. In this study, the effects of the KELS imaging technique and subtraction energy width of the energy window was investigated with respect to the contrast, standard deviation, and CNR with a Monte Carlo simulation. We simulated the PCD X-ray imaging system based on a CdTe and polymethylmethacrylate (PMMA) phantom which consists of the various iodine contrast agents. To acquired KELS images, images of the phantom using above and below the iodine contrast agent K-edge absorption energy (33.2 keV) have been acquired at different energy range. According to the results, the contrast and standard deviation were decreased, when subtraction energy width of the energy window is increased. Also, the CNR using a KELS imaging technique is higher than that of the images acquired by using whole energy range. Especially, the maximum differences of CNR between whole energy range and KELS images using a 1, 2, and 3 mm diameter iodine contrast agent were acquired 11.33, 8.73, and 8.29 times, respectively. Additionally, the optimum subtraction energy width of the energy window can be acquired at 5, 4, and 3 keV for the 1, 2, and 3 mm diameter iodine contrast agent, respectively. In conclusion, we successfully established an improved KELS imaging technique and optimized subtraction energy width of the energy window, and based on

  8. Classification of visible and infrared hyperspectral images based on image segmentation and edge-preserving filtering

    NASA Astrophysics Data System (ADS)

    Cui, Binge; Ma, Xiudan; Xie, Xiaoyun; Ren, Guangbo; Ma, Yi

    2017-03-01

    The classification of hyperspectral images with a few labeled samples is a major challenge which is difficult to meet unless some spatial characteristics can be exploited. In this study, we proposed a novel spectral-spatial hyperspectral image classification method that exploited spatial autocorrelation of hyperspectral images. First, image segmentation is performed on the hyperspectral image to assign each pixel to a homogeneous region. Second, the visible and infrared bands of hyperspectral image are partitioned into multiple subsets of adjacent bands, and each subset is merged into one band. Recursive edge-preserving filtering is performed on each merged band which utilizes the spectral information of neighborhood pixels. Third, the resulting spectral and spatial feature band set is classified using the SVM classifier. Finally, bilateral filtering is performed to remove "salt-and-pepper" noise in the classification result. To preserve the spatial structure of hyperspectral image, edge-preserving filtering is applied independently before and after the classification process. Experimental results on different hyperspectral images prove that the proposed spectral-spatial classification approach is robust and offers more classification accuracy than state-of-the-art methods when the number of labeled samples is small.

  9. Multispectral image sharpening using wavelet transform techniques and spatial correlation of edges

    USGS Publications Warehouse

    Lemeshewsky, George P.; Schowengerdt, Robert A.

    2000-01-01

    Several reported image fusion or sharpening techniques are based on the discrete wavelet transform (DWT). The technique described here uses a pixel-based maximum selection rule to combine respective transform coefficients of lower spatial resolution near-infrared (NIR) and higher spatial resolution panchromatic (pan) imagery to produce a sharpened NIR image. Sharpening assumes a radiometric correlation between the spectral band images. However, there can be poor correlation, including edge contrast reversals (e.g., at soil-vegetation boundaries), between the fused images and, consequently, degraded performance. To improve sharpening, a local area-based correlation technique originally reported for edge comparison with image pyramid fusion is modified for application with the DWT process. Further improvements are obtained by using redundant, shift-invariant implementation of the DWT. Example images demonstrate the improvements in NIR image sharpening with higher resolution pan imagery.

  10. Prediction of Iron K-Edge Absorption Spectra Using Time-Dependent Density Functional Theory

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    George, S.DeBeer; Petrenko, T.; Neese, F.

    2009-05-14

    Iron K-edge X-ray absorption pre-edge features have been calculated using a time-dependent density functional approach. The influence of functional, solvation, and relativistic effects on the calculated energies and intensities has been examined by correlation of the calculated parameters to experimental data on a series of 10 iron model complexes, which span a range of high-spin and low-spin ferrous and ferric complexes in O{sub h} to T{sub d} geometries. Both quadrupole and dipole contributions to the spectra have been calculated. We find that good agreement between theory and experiment is obtained by using the BP86 functional with the CP(PPP) basis setmore » on the Fe and TZVP one of the remaining atoms. Inclusion of solvation yields a small improvement in the calculated energies. However, the inclusion of scalar relativistic effects did not yield any improved correlation with experiment. The use of these methods to uniquely assign individual spectral transitions and to examine experimental contributions to backbonding is discussed.« less

  11. Microanalysis of iron oxidation state in iron oxides using X Ray Absorption Near Edge Structure (XANES)

    NASA Technical Reports Server (NTRS)

    Sutton, S. R.; Delaney, J.; Bajt, S.; Rivers, M. L.; Smith, J. V.

    1993-01-01

    An exploratory application of x ray absorption near edge structure (XANES) analysis using the synchrotron x ray microprobe was undertaken to obtain Fe XANES spectra on individual sub-millimeter grains in conventional polished sections. The experiments concentrated on determinations of Fe valence in a suite of iron oxide minerals for which independent estimates of the iron speciation could be made by electron microprobe analysis and x ray diffraction.

  12. Surface modification study of borate materials from B K-edge X-ray absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Kasrai, Masoud; Fleet, Michael E.; Muthupari, Swaminathan; Li, D.; Bancroft, G. M.

    The B K-edge X-ray absorption near-edge structure (XANES) spectra of two borates with tetrahedrally-coordinated B [[4]B; natural danburite (CaB2Si2O8) and synthetic boron phosphate (BPO4)] have been recorded in total electron yield (TEY) and fluorescence yield (FY) modes to investigate the surface and bulk structure of these materials. The TEY XANES measurement shows that danburite is susceptible to surface damage involving conversion of [4]B sites to [3]B sites by reaction with moisture and/or mechanical abrasion (grinding, polishing, etc.). The bulk of the mineral is essentially unaffected. Commercial boron phosphate powder exhibits more extensive surface and bulk damage, which increases with air exposure but is recovered on heating at 650°C. In contrast to ELNES, the XANES technique is not affected by beam damage and when collected in the FY mode is capable of yielding meaningful information on the coordination and intermediate-range structure of B in borate and borosilicate materials.

  13. Combined Mössbauer spectroscopic, multi-edge X-ray absorption spectroscopic, and density functional theoretical study of the radical SAM enzyme spore photoproduct lyase.

    PubMed

    Silver, Sunshine C; Gardenghi, David J; Naik, Sunil G; Shepard, Eric M; Huynh, Boi Hanh; Szilagyi, Robert K; Broderick, Joan B

    2014-03-01

    Spore photoproduct lyase (SPL), a member of the radical S-adenosyl-L-methionine (SAM) superfamily, catalyzes the direct reversal of the spore photoproduct, a thymine dimer specific to bacterial spores, to two thymines. SPL requires SAM and a redox-active [4Fe-4S] cluster for catalysis. Mössbauer analysis of anaerobically purified SPL indicates the presence of a mixture of cluster states with the majority (40 %) as [2Fe-2S](2+) clusters and a smaller amount (15 %) as [4Fe-4S](2+) clusters. On reduction, the cluster content changes to primarily (60 %) [4Fe-4S](+). The speciation information from Mössbauer data allowed us to deconvolute iron and sulfur K-edge X-ray absorption spectra to uncover electronic (X-ray absorption near-edge structure, XANES) and geometric (extended X-ray absorption fine structure, EXAFS) structural features of the Fe-S clusters, and their interactions with SAM. The iron K-edge EXAFS data provide evidence for elongation of a [2Fe-2S] rhomb of the [4Fe-4S] cluster on binding SAM on the basis of an Fe···Fe scatterer at 3.0 Å. The XANES spectra of reduced SPL in the absence and presence of SAM overlay one another, indicating that SAM is not undergoing reductive cleavage. The X-ray absorption spectroscopy data for SPL samples and data for model complexes from the literature allowed the deconvolution of contributions from [2Fe-2S] and [4Fe-4S] clusters to the sulfur K-edge XANES spectra. The analysis of pre-edge features revealed electronic changes in the Fe-S clusters as a function of the presence of SAM. The spectroscopic findings were further corroborated by density functional theory calculations that provided insights into structural and electronic perturbations that can be correlated by considering the role of SAM as a catalyst or substrate.

  14. Automatic Generation of Wide Dynamic Range Image without Pseudo-Edge Using Integration of Multi-Steps Exposure Images

    NASA Astrophysics Data System (ADS)

    Migiyama, Go; Sugimura, Atsuhiko; Osa, Atsushi; Miike, Hidetoshi

    Recently, digital cameras are offering technical advantages rapidly. However, the shot image is different from the sight image generated when that scenery is seen with the naked eye. There are blown-out highlights and crushed blacks in the image that photographed the scenery of wide dynamic range. The problems are hardly generated in the sight image. These are contributory cause of difference between the shot image and the sight image. Blown-out highlights and crushed blacks are caused by the difference of dynamic range between the image sensor installed in a digital camera such as CCD and CMOS and the human visual system. Dynamic range of the shot image is narrower than dynamic range of the sight image. In order to solve the problem, we propose an automatic method to decide an effective exposure range in superposition of edges. We integrate multi-step exposure images using the method. In addition, we try to erase pseudo-edges using the process to blend exposure values. Afterwards, we get a pseudo wide dynamic range image automatically.

  15. Mapping Catalytically Relevant Edge Electronic States of MoS2

    PubMed Central

    2018-01-01

    Molybdenum disulfide (MoS2) is a semiconducting transition metal dichalcogenide that is known to be a catalyst for both the hydrogen evolution reaction (HER) as well as for hydro-desulfurization (HDS) of sulfur-rich hydrocarbon fuels. Specifically, the edges of MoS2 nanostructures are known to be far more catalytically active as compared to unmodified basal planes. However, in the absence of the precise details of the geometric and electronic structure of the active catalytic sites, a rational means of modulating edge reactivity remain to be developed. Here we demonstrate using first-principles calculations, X-ray absorption spectroscopy, as well as scanning transmission X-ray microscopy (STXM) imaging that edge corrugations yield distinctive spectroscopic signatures corresponding to increased localization of hybrid Mo 4d states. Independent spectroscopic signatures of such edge states are identified at both the S L2,3 and S K-edges with distinctive spatial localization of such states observed in S L2,3-edge STXM imaging. The presence of such low-energy hybrid states at the edge of the conduction band is seen to correlate with substantially enhanced electrocatalytic activity in terms of a lower Tafel slope and higher exchange current density. These results elucidate the nature of the edge electronic structure and provide a clear framework for its rational manipulation to enhance catalytic activity. PMID:29721532

  16. Quantitative characterization of edge enhancement in phase contrast x-ray imaging.

    PubMed

    Monnin, P; Bulling, S; Hoszowska, J; Valley, J F; Meuli, R; Verdun, F R

    2004-06-01

    The aim of this study was to model the edge enhancement effect in in-line holography phase contrast imaging. A simple analytical approach was used to quantify refraction and interference contrasts in terms of beam energy and imaging geometry. The model was applied to predict the peak intensity and frequency of the edge enhancement for images of cylindrical fibers. The calculations were compared with measurements, and the relationship between the spatial resolution of the detector and the amplitude of the phase contrast signal was investigated. Calculations using the analytical model were in good agreement with experimental results for nylon, aluminum and copper wires of 50 to 240 microm diameter, and with numerical simulations based on Fresnel-Kirchhoff theory. A relationship between the defocusing distance and the pixel size of the image detector was established. This analytical model is a useful tool for optimizing imaging parameters in phase contrast in-line holography, including defocusing distance, detector resolution and beam energy.

  17. Improvement of depth resolution on photoacoustic imaging using multiphoton absorption

    NASA Astrophysics Data System (ADS)

    Yamaoka, Yoshihisa; Fujiwara, Katsuji; Takamatsu, Tetsuro

    2007-07-01

    Commercial imaging systems, such as computed tomography and magnetic resonance imaging, are frequently used powerful tools for observing structures deep within the human body. However, they cannot precisely visualized several-tens micrometer-sized structures for lack of spatial resolution. In this presentation, we propose photoacoustic imaging using multiphoton absorption technique to generate ultrasonic waves as a means of improving depth resolution. Since the multiphoton absorption occurs at only the focus point and the employed infrared pulses deeply penetrate living tissues, it enables us to extract characteristic features of structures embedded in the living tissue. When nanosecond pulses from a 1064-nm Nd:YAG laser were focused on Rhodamine B/chloroform solution (absorption peak: 540 nm), the peak intensity of the generated photoacoustic signal was proportional to the square of the input pulse energy. This result shows that the photoacoustic signals can be induced by the two-photon absorption of infrared nanosecond pulse laser and also can be detected by a commercial low-frequency MHz transducer. Furthermore, in order to evaluate the depth resolution of multiphoton-photoacoustic imaging, we investigated the dependence of photoacoustic signal on depth position using a 1-mm-thick phantom in a water bath. We found that the depth resolution of two-photon photoacoustic imaging (1064 nm) is greater than that of one-photon photoacoustic imaging (532 nm). We conclude that evolving multiphoton-photoacoustic imaging technology renders feasible the investigation of biomedical phenomena at the deep layer in living tissue.

  18. Multiresolution edge detection using enhanced fuzzy c-means clustering for ultrasound image speckle reduction

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Tsantis, Stavros; Spiliopoulos, Stavros; Karnabatidis, Dimitrios

    Purpose: Speckle suppression in ultrasound (US) images of various anatomic structures via a novel speckle noise reduction algorithm. Methods: The proposed algorithm employs an enhanced fuzzy c-means (EFCM) clustering and multiresolution wavelet analysis to distinguish edges from speckle noise in US images. The edge detection procedure involves a coarse-to-fine strategy with spatial and interscale constraints so as to classify wavelet local maxima distribution at different frequency bands. As an outcome, an edge map across scales is derived whereas the wavelet coefficients that correspond to speckle are suppressed in the inverse wavelet transform acquiring the denoised US image. Results: A totalmore » of 34 thyroid, liver, and breast US examinations were performed on a Logiq 9 US system. Each of these images was subjected to the proposed EFCM algorithm and, for comparison, to commercial speckle reduction imaging (SRI) software and another well-known denoising approach, Pizurica's method. The quantification of the speckle suppression performance in the selected set of US images was carried out via Speckle Suppression Index (SSI) with results of 0.61, 0.71, and 0.73 for EFCM, SRI, and Pizurica's methods, respectively. Peak signal-to-noise ratios of 35.12, 33.95, and 29.78 and edge preservation indices of 0.94, 0.93, and 0.86 were found for the EFCM, SIR, and Pizurica's method, respectively, demonstrating that the proposed method achieves superior speckle reduction performance and edge preservation properties. Based on two independent radiologists’ qualitative evaluation the proposed method significantly improved image characteristics over standard baseline B mode images, and those processed with the Pizurica's method. Furthermore, it yielded results similar to those for SRI for breast and thyroid images significantly better results than SRI for liver imaging, thus improving diagnostic accuracy in both superficial and in-depth structures. Conclusions: A new wavelet

  19. Multiresolution edge detection using enhanced fuzzy c-means clustering for ultrasound image speckle reduction.

    PubMed

    Tsantis, Stavros; Spiliopoulos, Stavros; Skouroliakou, Aikaterini; Karnabatidis, Dimitrios; Hazle, John D; Kagadis, George C

    2014-07-01

    Speckle suppression in ultrasound (US) images of various anatomic structures via a novel speckle noise reduction algorithm. The proposed algorithm employs an enhanced fuzzy c-means (EFCM) clustering and multiresolution wavelet analysis to distinguish edges from speckle noise in US images. The edge detection procedure involves a coarse-to-fine strategy with spatial and interscale constraints so as to classify wavelet local maxima distribution at different frequency bands. As an outcome, an edge map across scales is derived whereas the wavelet coefficients that correspond to speckle are suppressed in the inverse wavelet transform acquiring the denoised US image. A total of 34 thyroid, liver, and breast US examinations were performed on a Logiq 9 US system. Each of these images was subjected to the proposed EFCM algorithm and, for comparison, to commercial speckle reduction imaging (SRI) software and another well-known denoising approach, Pizurica's method. The quantification of the speckle suppression performance in the selected set of US images was carried out via Speckle Suppression Index (SSI) with results of 0.61, 0.71, and 0.73 for EFCM, SRI, and Pizurica's methods, respectively. Peak signal-to-noise ratios of 35.12, 33.95, and 29.78 and edge preservation indices of 0.94, 0.93, and 0.86 were found for the EFCM, SIR, and Pizurica's method, respectively, demonstrating that the proposed method achieves superior speckle reduction performance and edge preservation properties. Based on two independent radiologists' qualitative evaluation the proposed method significantly improved image characteristics over standard baseline B mode images, and those processed with the Pizurica's method. Furthermore, it yielded results similar to those for SRI for breast and thyroid images significantly better results than SRI for liver imaging, thus improving diagnostic accuracy in both superficial and in-depth structures. A new wavelet-based EFCM clustering model was introduced toward

  20. A new region-edge based level set model with applications to image segmentation

    NASA Astrophysics Data System (ADS)

    Zhi, Xuhao; Shen, Hong-Bin

    2018-04-01

    Level set model has advantages in handling complex shapes and topological changes, and is widely used in image processing tasks. The image segmentation oriented level set models can be grouped into region-based models and edge-based models, both of which have merits and drawbacks. Region-based level set model relies on fitting to color intensity of separated regions, but is not sensitive to edge information. Edge-based level set model evolves by fitting to local gradient information, but can get easily affected by noise. We propose a region-edge based level set model, which considers saliency information into energy function and fuses color intensity with local gradient information. The evolution of the proposed model is implemented by a hierarchical two-stage protocol, and the experimental results show flexible initialization, robust evolution and precise segmentation.

  1. The optimization of edge and line detectors for forest image analysis

    Treesearch

    Zhiling Long; Joseph Picone; Victor A. Rudis

    2000-01-01

    Automated image analysis for forestry applications is becoming increasingly important with the rapid evolution of satellite and land-based remote imaging industries. Features derived from line information play a very important role in analyses of such images. Many edge and line detection algorithms have been proposed but few, if any, comprehensive studies exist that...

  2. New scheme for image edge detection using the switching mechanism of nonlinear optical material

    NASA Astrophysics Data System (ADS)

    Pahari, Nirmalya; Mukhopadhyay, Sourangshu

    2006-03-01

    The limitations of electronics in conducting parallel arithmetic, algebraic, and logic processing are well known. Very high-speed (terahertz) performance cannot be expected in conventional electronic mechanisms. To achieve such performance we can introduce optics instead of electronics for information processing, computing, and data handling. Nonlinear optical material (NOM) is a successful candidate in this regard to play a major role in the domain of optically controlled switching systems. The character of some NOMs is such as to reflect the probe beam in the presence of two read beams (or pump beams) exciting the material from opposite directions, using the principle of four-wave mixing. In image processing, edge extraction from an image is an important and essential task. Several optical methods of digital image processing are used for properly evaluating the image edges. We propose here a new method of image edge detection, extraction, and enhancement by use of AND-based switching operations with NOM. In this process we have used the optically inverted image of a supplied image. This can be obtained by the EXOR switching operation of the NOM.

  3. HST/WFC3 Imaging and Multi-Wavelength Characterization of Edge-On Protoplanetary Disks

    NASA Astrophysics Data System (ADS)

    Gould, Carolina; Williams, Hayley; Duchene, Gaspard

    2017-10-01

    In recent years, the imaging detail in resolved protoplanetary disks has vastly improved and created a critical mass of objects to survey and compare properties, leading us to better understandings of system formation. In particular, disks with an edge-on inclination offer an important perspective, not only for the imaging convenience since the disk blocks stellar light, but scientifically an edge-on disk provides an otherwise impossible opportunity to observe vertical dust structure of a protoplanetary system. In this contribution, we compare seven HST-imaged edge-on protoplanetary disks in the Taurus, Chamaeleon and Ophiuchus star-forming regions, making note the variation in morphology (settled vs flared), dust properties revealed by multiwavelength color mapping, brightness variability over years timescales, and the presence in some systems of a blue-colored atmosphere far above the disk midplane. By using a uniform approach for their analysis, together these seven edge-on protoplanetary disk systems can give insights on evolutionary processes and inform future projects that explore this critical stage of planet formation.

  4. Backscatter absorption gas imaging systems and light sources therefore

    DOEpatents

    Kulp, Thomas Jan [Livermore, CA; Kliner, Dahv A. V. [San Ramon, CA; Sommers, Ricky [Oakley, CA; Goers, Uta-Barbara [Campbell, NY; Armstrong, Karla M [Livermore, CA

    2006-12-19

    The location of gases that are not visible to the unaided human eye can be determined using tuned light sources that spectroscopically probe the gases and cameras that can provide images corresponding to the absorption of the gases. The present invention is a light source for a backscatter absorption gas imaging (BAGI) system, and a light source incorporating the light source, that can be used to remotely detect and produce images of "invisible" gases. The inventive light source has a light producing element, an optical amplifier, and an optical parametric oscillator to generate wavelength tunable light in the IR. By using a multi-mode light source and an amplifier that operates using 915 nm pump sources, the power consumption of the light source is reduced to a level that can be operated by batteries for long periods of time. In addition, the light source is tunable over the absorption bands of many hydrocarbons, making it useful for detecting hazardous gases.

  5. Multispectral image sharpening using a shift-invariant wavelet transform and adaptive processing of multiresolution edges

    USGS Publications Warehouse

    Lemeshewsky, G.P.; Rahman, Z.-U.; Schowengerdt, R.A.; Reichenbach, S.E.

    2002-01-01

    Enhanced false color images from mid-IR, near-IR (NIR), and visible bands of the Landsat thematic mapper (TM) are commonly used for visually interpreting land cover type. Described here is a technique for sharpening or fusion of NIR with higher resolution panchromatic (Pan) that uses a shift-invariant implementation of the discrete wavelet transform (SIDWT) and a reported pixel-based selection rule to combine coefficients. There can be contrast reversals (e.g., at soil-vegetation boundaries between NIR and visible band images) and consequently degraded sharpening and edge artifacts. To improve performance for these conditions, I used a local area-based correlation technique originally reported for comparing image-pyramid-derived edges for the adaptive processing of wavelet-derived edge data. Also, using the redundant data of the SIDWT improves edge data generation. There is additional improvement because sharpened subband imagery is used with the edge-correlation process. A reported technique for sharpening three-band spectral imagery used forward and inverse intensity, hue, and saturation transforms and wavelet-based sharpening of intensity. This technique had limitations with opposite contrast data, and in this study sharpening was applied to single-band multispectral-Pan image pairs. Sharpening used simulated 30-m NIR imagery produced by degrading the spatial resolution of a higher resolution reference. Performance, evaluated by comparison between sharpened and reference image, was improved when sharpened subband data were used with the edge correlation.

  6. Combining Stereo SECCHI COR2 and HI1 Images for Automatic CME Front Edge Tracking

    NASA Technical Reports Server (NTRS)

    Kirnosov, Vladimir; Chang, Lin-Ching; Pulkkinen, Antti

    2016-01-01

    COR2 coronagraph images are the most commonly used data for coronal mass ejection (CME) analysis among the various types of data provided by the STEREO (Solar Terrestrial Relations Observatory) SECCHI (Sun-Earth Connection Coronal and Heliospheric Investigation) suite of instruments. The field of view (FOV) in COR2 images covers 215 solar radii (Rs) that allow for tracking the front edge of a CME in its initial stage to forecast the lead-time of a CME and its chances of reaching the Earth. However, estimating the lead-time of a CME using COR2 images gives a larger lead-time, which may be associated with greater uncertainty. To reduce this uncertainty, CME front edge tracking should be continued beyond the FOV of COR2 images. Therefore, heliospheric imager (HI1) data that covers 1590 Rs FOV must be included. In this paper, we propose a novel automatic method that takes both COR2 and HI1 images into account and combine the results to track the front edges of a CME continuously. The method consists of two modules: pre-processing and tracking. The pre-processing module produces a set of segmented images, which contain the signature of a CME, for both COR2 and HI1 separately. In addition, the HI1 images are resized and padded, so that the center of the Sun is the central coordinate of the resized HI1 images. The resulting COR2 andHI1 image set is then fed into the tracking module to estimate the position angle (PA) and track the front edge of a CME. The detected front edge is then used to produce a height-time profile that is used to estimate the speed of a CME. The method was validated using 15 CME events observed in the period from January 1, 2008 to August 31, 2009. The results demonstrate that the proposed method is effective for CME front edge tracking in both COR2 and HI1 images. Using this method, the CME front edge can now be tracked automatically and continuously in a much larger range, i.e., from 2 to 90 Rs, for the first time. These improvement scan greatly

  7. First-Principles Predictions of Near-Edge X-ray Absorption Fine Structure Spectra of Semiconducting Polymers

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Su, Gregory M.; Patel, Shrayesh N.; Pemmaraju, C. D.

    The electronic structure and molecular orientation of semiconducting polymers in thin films determine their ability to transport charge. Methods based on near-edge X-ray absorption fine structure (NEXAFS) spectroscopy can be used to probe both the electronic structure and microstructure of semiconducting polymers in both crystalline and amorphous films. However, it can be challenging to interpret NEXAFS spectra on the basis of experimental data alone, and accurate, predictive calculations are needed to complement experiments. Here, we show that first-principles density functional theory (DFT) can be used to model NEXAFS spectra of semiconducting polymers and to identify the nature of transitions inmore » complicated NEXAFS spectra. Core-level X-ray absorption spectra of a set of semiconducting polymers were calculated using the excited electron and core-hole (XCH) approach based on constrained-occupancy DFT. A comparison of calculations on model oligomers and periodic structures with experimental data revealed the requirements for accurate prediction of NEXAFS spectra of both conjugated homopolymers and donor–acceptor polymers. The NEXAFS spectra predicted by the XCH approach were applied to study molecular orientation in donor–acceptor polymers using experimental spectra and revealed the complexity of using carbon edge spectra in systems with large monomeric units. The XCH approach has sufficient accuracy in predicting experimental NEXAFS spectra of polymers that it should be considered for design and analysis of measurements using soft X-ray techniques, such as resonant soft X-ray scattering and scanning transmission X-ray microscopy.« less

  8. Soft X-ray absorption spectroscopy and resonant inelastic X-ray scattering spectroscopy below 100 eV: probing first-row transition-metal M-edges in chemical complexes

    PubMed Central

    Wang, Hongxin; Young, Anthony T.; Guo, Jinghua; Cramer, Stephen P.; Friedrich, Stephan; Braun, Artur; Gu, Weiwei

    2013-01-01

    X-ray absorption and scattering spectroscopies involving the 3d transition-metal K- and L-edges have a long history in studying inorganic and bioinorganic molecules. However, there have been very few studies using the M-edges, which are below 100 eV. Synchrotron-based X-ray sources can have higher energy resolution at M-edges. M-edge X-ray absorption spectroscopy (XAS) and resonant inelastic X-ray scattering (RIXS) could therefore provide complementary information to K- and L-edge spectroscopies. In this study, M 2,3-edge XAS on several Co, Ni and Cu complexes are measured and their spectral information, such as chemical shifts and covalency effects, are analyzed and discussed. In addition, M 2,3-edge RIXS on NiO, NiF2 and two other covalent complexes have been performed and different d–d transition patterns have been observed. Although still preliminary, this work on 3d metal complexes demonstrates the potential to use M-edge XAS and RIXS on more complicated 3d metal complexes in the future. The potential for using high-sensitivity and high-resolution superconducting tunnel junction X-ray detectors below 100 eV is also illustrated and discussed. PMID:23765304

  9. Detecting Edges in Images by Use of Fuzzy Reasoning

    NASA Technical Reports Server (NTRS)

    Dominguez, Jesus A.; Klinko, Steve

    2003-01-01

    A method of processing digital image data to detect edges includes the use of fuzzy reasoning. The method is completely adaptive and does not require any advance knowledge of an image. During initial processing of image data at a low level of abstraction, the nature of the data is indeterminate. Fuzzy reasoning is used in the present method because it affords an ability to construct useful abstractions from approximate, incomplete, and otherwise imperfect sets of data. Humans are able to make some sense of even unfamiliar objects that have imperfect high-level representations. It appears that to perceive unfamiliar objects or to perceive familiar objects in imperfect images, humans apply heuristic algorithms to understand the images

  10. Subgap Absorption in Conjugated Polymers

    DOE R&D Accomplishments Database

    Sinclair, M.; Seager, C. H.; McBranch, D.; Heeger, A. J; Baker, G. L.

    1991-01-01

    Along with X{sup (3)}, the magnitude of the optical absorption in the transparent window below the principal absorption edge is an important parameter which will ultimately determine the utility of conjugated polymers in active integrated optical devices. With an absorptance sensitivity of < 10{sup {minus}5}, Photothermal Deflection Spectroscopy (PDS) is ideal for determining the absorption coefficients of thin films of transparent'' materials. We have used PDS to measure the optical absorption spectra of the conjugated polymers poly(1,4-phenylene-vinylene) (and derivitives) and polydiacetylene-4BCMU in the spectral region from 0.55 eV to 3 eV. Our spectra show that the shape of the absorption edge varies considerably from polymer to polymer, with polydiacetylene-4BCMU having the steepest absorption edge. The minimum absorption coefficients measured varied somewhat with sample age and quality, but were typically in the range 1 cm{sup {minus}1} to 10 cm{sup {minus}1}. In the region below 1 eV, overtones of C-H stretching modes were observed, indicating that further improvements in transparency in this spectral region might be achieved via deuteration of fluorination.

  11. Edge-enhanced imaging with polyvinyl alcohol/acrylamide photopolymer gratings.

    PubMed

    Márquez, Andrés; Neipp, Cristian; Beléndez, Augusto; Gallego, Sergi; Ortuño, Manuel; Pascual, Inmaculada

    2003-09-01

    We demonstrate edge-enhanced imaging produced by volume phase gratings recorded on a polyvinyl alcohol/acrylamide photopolymer. Bragg diffraction, exhibited by volume gratings, modifies the impulse response of the imaging system, facilitating spatial filtering operations with no need for a physical Fourier plane. We demonstrate that Kogelnik's coupled-wave theory can be used to calculate the transfer function for the transmitted and the diffracted orders. The experimental and simulated results agree, and they demonstrate the feasibility of our proposal.

  12. Picosecond sulfur K-edge X-ray absorption spectroscopy with applications to excited state proton transfer

    DOE PAGES

    Van Kuiken, Benjamin E.; Ross, Matthew R.; Strader, Matthew L.; ...

    2017-05-08

    Picosecond X-ray absorption (XA) spectroscopy at the S K-edge (~2.4 keV) is demonstrated and used to monitor excited state dynamics in a small organosulfur molecule (2-Thiopyridone, 2TP) following optical excitation. Multiple studies have reported that the thione (2TP) is converted into the thiol (2-Mercaptopyridine, 2MP) following photoexcitation. However, the timescale and photochemical pathway of this reaction remain uncertain. In this work, time-resolved XA spectroscopy at the S K-edge is used to monitor the formation and decay of two transient species following 400nm excitation of 2TP dissolved in acetonitrile. The first transient species forms within the instrument response time (70 ps)more » and decays within 6 ns. The second transient species forms on a timescale of ~400 ps and decays on a 15 ns timescale. Time-dependent density functional theory is used to identify the first and second transient species as the lowestlying triplet states of 2TP and 2MP, respectively. This study demonstrates transient S K-edge XA spectroscopy as a sensitive and viable probe of time-evolving charge dynamics near sulfur sites in small molecules with future applications towards studying complex biological and material systems.« less

  13. Manganese L-edge X-ray absorption spectroscopy of manganese catalase from Lactobacillus plantarum and mixed valence manganese complexes

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Grush, M.M.; Chen, J.; George, S.J.

    1996-01-10

    The first Mn L-edge absorption spectra of a Mn metalloprotein are presented in this paper. Both reduced and superoxidized Mn catalase have been examined by fluorescence-detected soft X-ray absorption spectroscopy, and their Mn L-edge spectra are dramatically different. The spectrum of reduced Mn(II)Mn(II) catalase has been interpreted by ligand field atomic multiplet calculations and by comparison to model compound spectra. The analysis finds a 10 Dq value of nearly 1.1 eV, consistent with coordination by predominately nitrogen and oxygen donor ligands. For interpretation of mixed valence Mn spectra, an empirical simulation procedure based on the addition of homovalent model compoundmore » spectra has been developed and was tested on a variety of Mn complexes and superoxidized Mn catalase. This routine was also used to determine the oxidation state composition of the Mn in [Ba{sub 8}Na{sub 2}ClMn{sub 16}(OH){sub 8}(CO{sub 3}){sub 4}L{sub 8}] .53 H{sub 2}O (L=1,3-diamino-2-hydroxypropane-N,N,N`N`-tetraacetic acid). 27 refs., 6 figs.« less

  14. Single image super resolution algorithm based on edge interpolation in NSCT domain

    NASA Astrophysics Data System (ADS)

    Zhang, Mengqun; Zhang, Wei; He, Xinyu

    2017-11-01

    In order to preserve the texture and edge information and to improve the space resolution of single frame, a superresolution algorithm based on Contourlet (NSCT) is proposed. The original low resolution image is transformed by NSCT, and the directional sub-band coefficients of the transform domain are obtained. According to the scale factor, the high frequency sub-band coefficients are amplified by the interpolation method based on the edge direction to the desired resolution. For high frequency sub-band coefficients with noise and weak targets, Bayesian shrinkage is used to calculate the threshold value. The coefficients below the threshold are determined by the correlation among the sub-bands of the same scale to determine whether it is noise and de-noising. The anisotropic diffusion filter is used to effectively enhance the weak target in the low contrast region of the target and background. Finally, the high-frequency sub-band is amplified by the bilinear interpolation method to the desired resolution, and then combined with the high-frequency subband coefficients after de-noising and small target enhancement, the NSCT inverse transform is used to obtain the desired resolution image. In order to verify the effectiveness of the proposed algorithm, the proposed algorithm and several common image reconstruction methods are used to test the synthetic image, motion blurred image and hyperspectral image, the experimental results show that compared with the traditional single resolution algorithm, the proposed algorithm can obtain smooth edges and good texture features, and the reconstructed image structure is well preserved and the noise is suppressed to some extent.

  15. Theoretical X-ray production cross sections at incident photon energies across L{sub i} (i=1-3) absorption edges of Br

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Puri, Sanjiv

    The X-ray production (XRP) cross sections, σ{sub Lk} (k = l, η, α, β{sub 6}, β{sub 1}, β{sub 3}, β{sub 4}, β{sub 9,10}, γ{sub 1,5}, γ{sub 2,3}) have been evaluated at incident photon energies across the L{sub i}(i=1-3) absorption edge energies of {sub 35}Br using theoretical data sets of different physical parameters, namely, the L{sub i}(i=1-3) sub-shell the X-ray emission rates based on the Dirac-Fock (DF) model, the fluorescence and Coster Kronig yields based on the Dirac-Hartree-Slater (DHS) model, and two sets of the photoionisation cross sections based on the relativistic Hartree-Fock-Slater (RHFS) model and the Dirac-Fock (DF) model, inmore » order to highlight the importance of electron exchange effects at photon energies in vicinity of absorption edge energies.« less

  16. Edge detection and localization with edge pattern analysis and inflection characterization

    NASA Astrophysics Data System (ADS)

    Jiang, Bo

    2012-05-01

    In general edges are considered to be abrupt changes or discontinuities in two dimensional image signal intensity distributions. The accuracy of front-end edge detection methods in image processing impacts the eventual success of higher level pattern analysis downstream. To generalize edge detectors designed from a simple ideal step function model to real distortions in natural images, research on one dimensional edge pattern analysis to improve the accuracy of edge detection and localization proposes an edge detection algorithm, which is composed by three basic edge patterns, such as ramp, impulse, and step. After mathematical analysis, general rules for edge representation based upon the classification of edge types into three categories-ramp, impulse, and step (RIS) are developed to reduce detection and localization errors, especially reducing "double edge" effect that is one important drawback to the derivative method. But, when applying one dimensional edge pattern in two dimensional image processing, a new issue is naturally raised that the edge detector should correct marking inflections or junctions of edges. Research on human visual perception of objects and information theory pointed out that a pattern lexicon of "inflection micro-patterns" has larger information than a straight line. Also, research on scene perception gave an idea that contours have larger information are more important factor to determine the success of scene categorization. Therefore, inflections or junctions are extremely useful features, whose accurate description and reconstruction are significant in solving correspondence problems in computer vision. Therefore, aside from adoption of edge pattern analysis, inflection or junction characterization is also utilized to extend traditional derivative edge detection algorithm. Experiments were conducted to test my propositions about edge detection and localization accuracy improvements. The results support the idea that these edge

  17. The use of C-near edge X-ray absorption fine structure spectroscopy for the elaboration of chemistry in lignocellulosics

    Treesearch

    Lucian A. Lucia; Hiroki Nanko; Alan W. Rudie; Doug G. Mancosky; Sue Wirick

    2006-01-01

    The research presented elucidates the oxidation chemistry occurring in hydrogen peroxide bleached kraft pulp fibers by employing carbon near edge x-ray absorption fine structure spectroscopy (C-NEXAFS). C-NEXAFS is a soft x-ray technique that selectively interrogates atomic moieties using photoelectrons (Xrays) of variable energies. The X1A beam line at the National...

  18. Novel visualization studies of lignocellulosic oxidation chemistry by application of C-near edge X-ray absorption fine structure spectroscopy

    Treesearch

    Douglas G. Mancosky; Lucian A. Lucia; Hiroki Nanko; Sue Wirick; Alan W. Rudie; Robert Braun

    2005-01-01

    The research presented herein is the first attempt to probe the chemical nature of lignocellulosic samples by the application of carbon near edge X-ray absorption fine structure spectroscopy (C-NEXAFS). C-NEXAFS is a soft X-ray technique that principally provides selective interrogation of discrete atomic moieties using photoelectrons of variable energies. The X1A beam...

  19. Small angle x-ray scattering with edge-illumination

    NASA Astrophysics Data System (ADS)

    Modregger, Peter; Cremona, Tiziana P.; Benarafa, Charaf; Schittny, Johannes C.; Olivo, Alessandro; Endrizzi, Marco

    2016-08-01

    Sensitivity to sub-pixel sample features has been demonstrated as a valuable capability of phase contrast x-ray imaging. Here, we report on a method to obtain angular-resolved small angle x-ray scattering distributions with edge-illumination- based imaging utilizing incoherent illumination from an x-ray tube. Our approach provides both the three established image modalities (absorption, differential phase and scatter strength), plus a number of additional contrasts related to unresolved sample features. The complementarity of these contrasts is experimentally validated by using different materials in powder form. As a significant application example we show that the extended complementary contrasts could allow the diagnosis of pulmonary emphysema in a murine model. In support of this, we demonstrate that the properties of the retrieved scattering distributions are consistent with the expectation of increased feature sizes related to pulmonary emphysema. Combined with the simplicity of implementation of edge-illumination, these findings suggest a high potential for exploiting extended sub-pixel contrasts in the diagnosis of lung diseases and beyond.

  20. Cerium LIII-edge x-ray absorption study of the CexFe4-yCoySb12 skutterudites

    NASA Astrophysics Data System (ADS)

    Grandjean, Fernande; Long, Gary J.; Cortes, Robert; Morelli, Donald T.; Meisner, Gregory P.

    2000-11-01

    The cerium LIII-edge x-ray absorption near-edge spectra of the CexFe4-yCoySb12 compounds have been obtained at 295 K and unambiguously indicate that cerium is in the 4f1 electronic ground state for all values of 0.22<=x<=0.98 and 0.0<=y<=3.5. This stable trivalent state of cerium is in agreement with the proposed (CeFe4Sb12)1-α(□Co4Sb12)α, solid solution structure, in which the cerium atoms are always surrounded by twelve antimony first neighbors and six iron second neighbors, the observed magnetic properties of CeFe4Sb12 and Ce0.9Fe3CoSb12, and the electronic structure of CeFe4Sb12 obtained from band-structure calculations.

  1. MO-FG-CAMPUS-IeP1-01: Alternative K-Edge Filters for Low-Energy Image Acquisition in Contrast Enhanced Spectral Mammography

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Shrestha, S; Vedantham, S; Karellas, A

    Purpose: In Contrast Enhanced Spectral Mammography (CESM), Rh filter is often used during low-energy image acquisition. The potential for using Ag, In and Sn filters, which exhibit K-edge closer to, and just below that of Iodine, instead of the Rh filter, was investigated for the low-energy image acquisition. Methods: Analytical computations of the half-value thickness (HVT) and the photon fluence per mAs (photons/mm2/mAs) for 50µm Rh were compared with other potential K-edge filters (Ag, In and Sn), all with K-absorption edge below that of Iodine. Two strategies were investigated: fixed kVp and filter thickness (50µm for all filters) resulting inmore » HVT variation, and fixed kVp and HVT resulting in variation in Ag, In and Sn thickness. Monte Carlo simulations (GEANT4) were conducted to determine if the scatter-to-primary ratio (SPR) and the point spread function of scatter (scatter PSF) differed between Rh and other K-edge filters. Results: Ag, In and Sn filters (50µm thick) increased photon fluence/mAs by 1.3–1.4, 1.8–2, and 1.7–2 at 28-32 kVp compared to 50µm Rh, which could decrease exposure time. Additionally, the fraction of spectra closer to and just below Iodine’s K-edge increased with these filters, which could improve post-subtraction image contrast. For HVT matched to 50µm Rh filtered spectra, the thickness range for Ag, In, and Sn were (41,44)µm, (49,55)µm and (45,53)µm, and increased photon fluence/mAs by 1.5–1.7, 1.6–2, and 1.6–2.2, respectively. Monte Carlo simulations showed that neither the SPR nor the scatter PSF of Ag, In and Sn differed from Rh, indicating no additional detriment due to x-ray scatter. Conclusion: The use of Ag, In and Sn filters for low-energy image acquisition in CESM is potentially feasible and could decrease exposure time and may improve post-subtraction image contrast. Effect of these filters on radiation dose, contrast, noise and associated metrics are being investigated. Funding Support

  2. Parallel algorithm for determining motion vectors in ice floe images by matching edge features

    NASA Technical Reports Server (NTRS)

    Manohar, M.; Ramapriyan, H. K.; Strong, J. P.

    1988-01-01

    A parallel algorithm is described to determine motion vectors of ice floes using time sequences of images of the Arctic ocean obtained from the Synthetic Aperture Radar (SAR) instrument flown on-board the SEASAT spacecraft. Researchers describe a parallel algorithm which is implemented on the MPP for locating corresponding objects based on their translationally and rotationally invariant features. The algorithm first approximates the edges in the images by polygons or sets of connected straight-line segments. Each such edge structure is then reduced to a seed point. Associated with each seed point are the descriptions (lengths, orientations and sequence numbers) of the lines constituting the corresponding edge structure. A parallel matching algorithm is used to match packed arrays of such descriptions to identify corresponding seed points in the two images. The matching algorithm is designed such that fragmentation and merging of ice floes are taken into account by accepting partial matches. The technique has been demonstrated to work on synthetic test patterns and real image pairs from SEASAT in times ranging from .5 to 0.7 seconds for 128 x 128 images.

  3. Energy-Looping Nanoparticles: Harnessing Excited-State Absorption for Deep-Tissue Imaging.

    PubMed

    Levy, Elizabeth S; Tajon, Cheryl A; Bischof, Thomas S; Iafrati, Jillian; Fernandez-Bravo, Angel; Garfield, David J; Chamanzar, Maysamreza; Maharbiz, Michel M; Sohal, Vikaas S; Schuck, P James; Cohen, Bruce E; Chan, Emory M

    2016-09-27

    Near infrared (NIR) microscopy enables noninvasive imaging in tissue, particularly in the NIR-II spectral range (1000-1400 nm) where attenuation due to tissue scattering and absorption is minimized. Lanthanide-doped upconverting nanocrystals are promising deep-tissue imaging probes due to their photostable emission in the visible and NIR, but these materials are not efficiently excited at NIR-II wavelengths due to the dearth of lanthanide ground-state absorption transitions in this window. Here, we develop a class of lanthanide-doped imaging probes that harness an energy-looping mechanism that facilitates excitation at NIR-II wavelengths, such as 1064 nm, that are resonant with excited-state absorption transitions but not ground-state absorption. Using computational methods and combinatorial screening, we have identified Tm(3+)-doped NaYF4 nanoparticles as efficient looping systems that emit at 800 nm under continuous-wave excitation at 1064 nm. Using this benign excitation with standard confocal microscopy, energy-looping nanoparticles (ELNPs) are imaged in cultured mammalian cells and through brain tissue without autofluorescence. The 1 mm imaging depths and 2 μm feature sizes are comparable to those demonstrated by state-of-the-art multiphoton techniques, illustrating that ELNPs are a promising class of NIR probes for high-fidelity visualization in cells and tissue.

  4. Implementing a Parallel Image Edge Detection Algorithm Based on the Otsu-Canny Operator on the Hadoop Platform.

    PubMed

    Cao, Jianfang; Chen, Lichao; Wang, Min; Tian, Yun

    2018-01-01

    The Canny operator is widely used to detect edges in images. However, as the size of the image dataset increases, the edge detection performance of the Canny operator decreases and its runtime becomes excessive. To improve the runtime and edge detection performance of the Canny operator, in this paper, we propose a parallel design and implementation for an Otsu-optimized Canny operator using a MapReduce parallel programming model that runs on the Hadoop platform. The Otsu algorithm is used to optimize the Canny operator's dual threshold and improve the edge detection performance, while the MapReduce parallel programming model facilitates parallel processing for the Canny operator to solve the processing speed and communication cost problems that occur when the Canny edge detection algorithm is applied to big data. For the experiments, we constructed datasets of different scales from the Pascal VOC2012 image database. The proposed parallel Otsu-Canny edge detection algorithm performs better than other traditional edge detection algorithms. The parallel approach reduced the running time by approximately 67.2% on a Hadoop cluster architecture consisting of 5 nodes with a dataset of 60,000 images. Overall, our approach system speeds up the system by approximately 3.4 times when processing large-scale datasets, which demonstrates the obvious superiority of our method. The proposed algorithm in this study demonstrates both better edge detection performance and improved time performance.

  5. Infrared image enhancement based on the edge detection and mathematical morphology

    NASA Astrophysics Data System (ADS)

    Zhang, Linlin; Zhao, Yuejin; Dong, Liquan; Liu, Xiaohua; Yu, Xiaomei; Hui, Mei; Chu, Xuhong; Gong, Cheng

    2010-11-01

    The development of the un-cooled infrared imaging technology from military necessity. At present, It is widely applied in industrial, medicine, scientific and technological research and so on. The infrared radiation temperature distribution of the measured object's surface can be observed visually. The collection of infrared images from our laboratory has following characteristics: Strong spatial correlation, Low contrast , Poor visual effect; Without color or shadows because of gray image , and has low resolution; Low definition compare to the visible light image; Many kinds of noise are brought by the random disturbances of the external environment. Digital image processing are widely applied in many areas, it can now be studied up close and in detail in many research field. It has become one kind of important means of the human visual continuation. Traditional methods for image enhancement cannot capture the geometric information of images and tend to amplify noise. In order to remove noise and improve visual effect. Meanwhile, To overcome the above enhancement issues. The mathematical model of FPA unit was constructed based on matrix transformation theory. According to characteristics of FPA, Image enhancement algorithm which combined with mathematical morphology and edge detection are established. First of all, Image profile is obtained by using the edge detection combine with mathematical morphological operators. And then, through filling the template profile by original image to get the ideal background image, The image noise can be removed on the base of the above method. The experiments show that utilizing the proposed algorithm can enhance image detail and the signal to noise ratio.

  6. Airborne imaging spectrometer data of the Ruby Mountains, Montana: Mineral discrimination using relative absorption band-depth images

    USGS Publications Warehouse

    Crowley, J.K.; Brickey, D.W.; Rowan, L.C.

    1989-01-01

    Airborne imaging spectrometer data collected in the near-infrared (1.2-2.4 ??m) wavelength range were used to study the spectral expression of metamorphic minerals and rocks in the Ruby Mountains of southwestern Montana. The data were analyzed by using a new data enhancement procedure-the construction of relative absorption band-depth (RBD) images. RBD images, like bandratio images, are designed to detect diagnostic mineral absorption features, while minimizing reflectance variations related to topographic slope and albedo differences. To produce an RBD image, several data channels near an absorption band shoulder are summed and then divided by the sum of several channels located near the band minimum. RBD images are both highly specific and sensitive to the presence of particular mineral absorption features. Further, the technique does not distort or subdue spectral features as sometimes occurs when using other data normalization methods. By using RBD images, a number of rock and soil units were distinguished in the Ruby Mountains including weathered quartz - feldspar pegmatites, marbles of several compositions, and soils developed over poorly exposed mica schists. The RBD technique is especially well suited for detecting weak near-infrared spectral features produced by soils, which may permit improved mapping of subtle lithologic and structural details in semiarid terrains. The observation of soils rich in talc, an important industrial commodity in the study area, also indicates that RBD images may be useful for mineral exploration. ?? 1989.

  7. Modeling L2,3-Edge X-ray Absorption Spectroscopy with Real-Time Exact Two-Component Relativistic Time-Dependent Density Functional Theory.

    PubMed

    Kasper, Joseph M; Lestrange, Patrick J; Stetina, Torin F; Li, Xiaosong

    2018-04-10

    X-ray absorption spectroscopy is a powerful technique to probe local electronic and nuclear structure. There has been extensive theoretical work modeling K-edge spectra from first principles. However, modeling L-edge spectra directly with density functional theory poses a unique challenge requiring further study. Spin-orbit coupling must be included in the model, and a noncollinear density functional theory is required. Using the real-time exact two-component method, we are able to variationally include one-electron spin-orbit coupling terms when calculating the absorption spectrum. The abilities of different basis sets and density functionals to model spectra for both closed- and open-shell systems are investigated using SiCl 4 and three transition metal complexes, TiCl 4 , CrO 2 Cl 2 , and [FeCl 6 ] 3- . Although we are working in the real-time framework, individual molecular orbital transitions can still be recovered by projecting the density onto the ground state molecular orbital space and separating contributions to the time evolving dipole moment.

  8. Edge co-occurrences can account for rapid categorization of natural versus animal images

    NASA Astrophysics Data System (ADS)

    Perrinet, Laurent U.; Bednar, James A.

    2015-06-01

    Making a judgment about the semantic category of a visual scene, such as whether it contains an animal, is typically assumed to involve high-level associative brain areas. Previous explanations require progressively analyzing the scene hierarchically at increasing levels of abstraction, from edge extraction to mid-level object recognition and then object categorization. Here we show that the statistics of edge co-occurrences alone are sufficient to perform a rough yet robust (translation, scale, and rotation invariant) scene categorization. We first extracted the edges from images using a scale-space analysis coupled with a sparse coding algorithm. We then computed the “association field” for different categories (natural, man-made, or containing an animal) by computing the statistics of edge co-occurrences. These differed strongly, with animal images having more curved configurations. We show that this geometry alone is sufficient for categorization, and that the pattern of errors made by humans is consistent with this procedure. Because these statistics could be measured as early as the primary visual cortex, the results challenge widely held assumptions about the flow of computations in the visual system. The results also suggest new algorithms for image classification and signal processing that exploit correlations between low-level structure and the underlying semantic category.

  9. Half-quadratic variational regularization methods for speckle-suppression and edge-enhancement in SAR complex image

    NASA Astrophysics Data System (ADS)

    Zhao, Xia; Wang, Guang-xin

    2008-12-01

    Synthetic aperture radar (SAR) is an active remote sensing sensor. It is a coherent imaging system, the speckle is its inherent default, which affects badly the interpretation and recognition of the SAR targets. Conventional methods of removing the speckle is studied usually in real SAR image, which reduce the edges of the images at the same time as depressing the speckle. Morever, Conventional methods lost the information about images phase. Removing the speckle and enhancing the target and edge simultaneously are still a puzzle. To suppress the spckle and enhance the targets and the edges simultaneously, a half-quadratic variational regularization method in complex SAR image is presented, which is based on the prior knowledge of the targets and the edge. Due to the non-quadratic and non- convex quality and the complexity of the cost function, a half-quadratic variational regularization variation is used to construct a new cost function,which is solved by alternate optimization. In the proposed scheme, the construction of the model, the solution of the model and the selection of the model peremeters are studied carefully. In the end, we validate the method using the real SAR data.Theoretic analysis and the experimental results illustrate the the feasibility of the proposed method. Further more, the proposed method can preserve the information about images phase.

  10. Implementing a Parallel Image Edge Detection Algorithm Based on the Otsu-Canny Operator on the Hadoop Platform

    PubMed Central

    Wang, Min; Tian, Yun

    2018-01-01

    The Canny operator is widely used to detect edges in images. However, as the size of the image dataset increases, the edge detection performance of the Canny operator decreases and its runtime becomes excessive. To improve the runtime and edge detection performance of the Canny operator, in this paper, we propose a parallel design and implementation for an Otsu-optimized Canny operator using a MapReduce parallel programming model that runs on the Hadoop platform. The Otsu algorithm is used to optimize the Canny operator's dual threshold and improve the edge detection performance, while the MapReduce parallel programming model facilitates parallel processing for the Canny operator to solve the processing speed and communication cost problems that occur when the Canny edge detection algorithm is applied to big data. For the experiments, we constructed datasets of different scales from the Pascal VOC2012 image database. The proposed parallel Otsu-Canny edge detection algorithm performs better than other traditional edge detection algorithms. The parallel approach reduced the running time by approximately 67.2% on a Hadoop cluster architecture consisting of 5 nodes with a dataset of 60,000 images. Overall, our approach system speeds up the system by approximately 3.4 times when processing large-scale datasets, which demonstrates the obvious superiority of our method. The proposed algorithm in this study demonstrates both better edge detection performance and improved time performance. PMID:29861711

  11. Chemical forms of sulfur in geological and archeological asphaltenes from Middle East, France, and Spain determined by sulfur K- and L-edge X-ray absorption near-edge structure spectroscopy

    NASA Astrophysics Data System (ADS)

    Sarret, Géraldine; Connan, Jacques; Kasrai, Masoud; Bancroft, G. Michael; Charrié-Duhaut, Armelle; Lemoine, Sylvie; Adam, Pierre; Albrecht, Pierre; Eybert-Bérard, Laurent

    1999-11-01

    Asphaltene samples extracted from archeological and geological bitumens from the Middle East, France, and Spain were studied by sulfur K- and L-edge X-ray absorption near-edge structure (XANES) spectroscopy in combination with isotopic analyses (δ 13C and δD). Within each series, the samples were genetically related by their δ 13C values. The gross and elemental composition and the δD values were used to characterize the weathering state of the samples. Sulfur K- and L-edge XANES results show that in all the samples, dibenzothiophenes are the dominant forms of sulfur. In the least oxidized asphaltenes, minor species include disulfides, alkyl and aryl sulfides, and sulfoxides. With increasing alteration the proportion of oxidized sulfur (sulfoxides, sulfones, sulfonates and sulfates) increases, whereas the disulfide and sulfide content decreases. This evolution is observed in all the series, regardless of the origin of the asphaltenes. This work illustrates the advantages of XANES spectroscopy as a selective probe for determining sulfur speciation in natural samples. It also shows that S K- and L-edge XANES spectroscopy are complementary for identifying the oxidized and reduced forms of sulfur, respectively.

  12. Pushing the limits of CMOS optical parametric amplifiers with USRN:Si7N3 above the two-photon absorption edge

    PubMed Central

    Ooi, K. J. A.; Ng, D. K. T.; Wang, T.; Chee, A. K. L.; Ng, S. K.; Wang, Q.; Ang, L. K.; Agarwal, A. M.; Kimerling, L. C.; Tan, D. T. H.

    2017-01-01

    CMOS platforms operating at the telecommunications wavelength either reside within the highly dissipative two-photon regime in silicon-based optical devices, or possess small nonlinearities. Bandgap engineering of non-stoichiometric silicon nitride using state-of-the-art fabrication techniques has led to our development of USRN (ultra-silicon-rich nitride) in the form of Si7N3, that possesses a high Kerr nonlinearity (2.8 × 10−13 cm2 W−1), an order of magnitude larger than that in stoichiometric silicon nitride. Here we experimentally demonstrate high-gain optical parametric amplification using USRN, which is compositionally tailored such that the 1,550 nm wavelength resides above the two-photon absorption edge, while still possessing large nonlinearities. Optical parametric gain of 42.5 dB, as well as cascaded four-wave mixing with gain down to the third idler is observed and attributed to the high photon efficiency achieved through operating above the two-photon absorption edge, representing one of the largest optical parametric gains to date on a CMOS platform. PMID:28051064

  13. Superpixel edges for boundary detection

    DOEpatents

    Moya, Mary M.; Koch, Mark W.

    2016-07-12

    Various embodiments presented herein relate to identifying one or more edges in a synthetic aperture radar (SAR) image comprising a plurality of superpixels. Superpixels sharing an edge (or boundary) can be identified and one or more properties of the shared superpixels can be compared to determine whether the superpixels form the same or two different features. Where the superpixels form the same feature the edge is identified as an internal edge. Where the superpixels form two different features, the edge is identified as an external edge. Based upon classification of the superpixels, the external edge can be further determined to form part of a roof, wall, etc. The superpixels can be formed from a speckle-reduced SAR image product formed from a registered stack of SAR images, which is further segmented into a plurality of superpixels. The edge identification process is applied to the SAR image comprising the superpixels and edges.

  14. Near- and Extended-Edge X-Ray-Absorption Fine-Structure Spectroscopy Using Ultrafast Coherent High-Order Harmonic Supercontinua

    NASA Astrophysics Data System (ADS)

    Popmintchev, Dimitar; Galloway, Benjamin R.; Chen, Ming-Chang; Dollar, Franklin; Mancuso, Christopher A.; Hankla, Amelia; Miaja-Avila, Luis; O'Neil, Galen; Shaw, Justin M.; Fan, Guangyu; Ališauskas, Skirmantas; Andriukaitis, Giedrius; Balčiunas, Tadas; Mücke, Oliver D.; Pugzlys, Audrius; Baltuška, Andrius; Kapteyn, Henry C.; Popmintchev, Tenio; Murnane, Margaret M.

    2018-03-01

    Recent advances in high-order harmonic generation have made it possible to use a tabletop-scale setup to produce spatially and temporally coherent beams of light with bandwidth spanning 12 octaves, from the ultraviolet up to x-ray photon energies >1.6 keV . Here we demonstrate the use of this light for x-ray-absorption spectroscopy at the K - and L -absorption edges of solids at photon energies near 1 keV. We also report x-ray-absorption spectroscopy in the water window spectral region (284-543 eV) using a high flux high-order harmonic generation x-ray supercontinuum with 109 photons/s in 1% bandwidth, 3 orders of magnitude larger than has previously been possible using tabletop sources. Since this x-ray radiation emerges as a single attosecond-to-femtosecond pulse with peak brightness exceeding 1026 photons/s /mrad2/mm2/1 % bandwidth, these novel coherent x-ray sources are ideal for probing the fastest molecular and materials processes on femtosecond-to-attosecond time scales and picometer length scales.

  15. Neutron Bragg-edge-imaging for strain mapping under in situ tensile loading

    NASA Astrophysics Data System (ADS)

    Woracek, R.; Penumadu, D.; Kardjilov, N.; Hilger, A.; Strobl, M.; Wimpory, R. C.; Manke, I.; Banhart, J.

    2011-05-01

    Wavelength selective neutron radiography at a cold neutron reactor source was used to measure strain and determine (residual) stresses in a steel sample under plane stress conditions. We present a new technique that uses an energy-resolved neutron imaging system based on a double crystal monochromator and is equipped with a specially developed (in situ) biaxial load frame to perform Bragg edge based transmission imaging. The neutron imaging technique provides a viewing area of 7 cm by 7 cm with a spatial resolution on the order of ˜ 100 μm. The stress-induced shifts of the Bragg edge corresponding to the (110) lattice plane were resolved spatially for a ferritic steel alloy A36 (ASTM international) sample. Furthermore it is demonstrated that results agree with comparative data obtained using neutron diffraction and resistance based strain-gauge rosettes.

  16. Invited Review Article: Gas puff imaging diagnostics of edge plasma turbulence in magnetic fusion devices

    DOE PAGES

    Zweben, S. J.; Terry, J. L.; Stotler, D. P.; ...

    2017-04-27

    Gas puff imaging (GPI) is a diagnostic of plasma turbulence which uses a puff of neutral gas at the plasma edge to increase the local visible light emission for improved space-time resolution of plasma fluctuations. This paper reviews gas puff imaging diagnostics of edge plasma turbulence in magnetic fusion research, with a focus on the instrumentation, diagnostic cross-checks, and interpretation issues. The gas puff imaging hardware, optics, and detectors are described for about 10 GPI systems implemented over the past similar to 15 years. Comparison of GPI results with other edge turbulence diagnostic results is described, and many common featuresmore » are observed. Here, several issues in the interpretation of GPI measurements are discussed, and potential improvements in hardware and modeling are suggested.« less

  17. Invited Review Article: Gas puff imaging diagnostics of edge plasma turbulence in magnetic fusion devices

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zweben, S. J.; Terry, J. L.; Stotler, D. P.

    Gas puff imaging (GPI) is a diagnostic of plasma turbulence which uses a puff of neutral gas at the plasma edge to increase the local visible light emission for improved space-time resolution of plasma fluctuations. This paper reviews gas puff imaging diagnostics of edge plasma turbulence in magnetic fusion research, with a focus on the instrumentation, diagnostic cross-checks, and interpretation issues. The gas puff imaging hardware, optics, and detectors are described for about 10 GPI systems implemented over the past similar to 15 years. Comparison of GPI results with other edge turbulence diagnostic results is described, and many common featuresmore » are observed. Here, several issues in the interpretation of GPI measurements are discussed, and potential improvements in hardware and modeling are suggested.« less

  18. Si K EDGE STRUCTURE AND VARIABILITY IN GALACTIC X-RAY BINARIES

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Schulz, Norbert S.; Corrales, Lia; Canizares, Claude R.

    2016-08-10

    We survey the Si K edge structure in various absorbed Galactic low-mass X-ray binaries (LMXBs) to study states of silicon in the inter- and circum-stellar medium. The bulk of these LMXBs lie toward the Galactic bulge region and all have column densities above 10{sup 22} cm{sup −2}. The observations were performed using the Chandra High Energy Transmission Grating Spectrometer. The Si K edge in all sources appears at an energy value of 1844 ± 0.001 eV. The edge exhibits significant substructure that can be described by a near edge absorption feature at 1849 ± 0.002 eV and a far edgemore » absorption feature at 1865 ± 0.002 eV. Both of these absorption features appear variable with equivalent widths up to several mÅ. We can describe the edge structure using several components: multiple edge functions, near edge absorption excesses from silicates in dust form, signatures from X-ray scattering optical depths, and a variable warm absorber from ionized atomic silicon. The measured optical depths of the edges indicate much higher values than expected from atomic silicon cross sections and interstellar medium abundances, and they appear consistent with predictions from silicate X-ray absorption and scattering. A comparison with models also indicates a preference for larger dust grain sizes. In many cases, we identify Si xiii resonance absorption and determine ionization parameters between log ξ = 1.8 and 2.8 and turbulent velocities between 300 and 1000 km s{sup −1}. This places the warm absorber in close vicinity of the X-ray binaries. In some data, we observe a weak edge at 1.840 keV, potentially from a lesser contribution of neutral atomic silicon.« less

  19. The interaction of copper ions with Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli: an X-ray absorption near-edge structure (XANES) spectroscopy study.

    PubMed

    Zanzen, Ulrike; Bovenkamp-Langlois, Lisa; Klysubun, Wantana; Hormes, Josef; Prange, Alexander

    2018-04-01

    The antimicrobial properties of copper ions have been known for a long time. However, the exact mechanism of action of the transition metal on microorganisms has long been unclear. X-ray absorption near-edge structure (XANES) spectroscopy at the Cu K edge allows the determination of copper speciation in Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa that have been treated with Cu(II) and Cu(I) solutions. The death/inactivation of the bacteria was observed using plate counting and light microscopy. The Cu K-XANES spectra of the two Gram-negative bacteria are different than those of the Gram-positive strain. The results clearly show that the Cu + -S bond contributes to the antibacterial activity of copper, as in the case of silver. The detailed evaluation of the differentiated absorption spectra shows that Cu + (not Cu 2+ ) is the dominant ion that binds to the bacteria. Because Cu + is not the most common copper ion, copper is not as effective an antibacterial agent as silver, whose common valency is actually + 1. Any reaction of copper with phosphorus from the bacteria can be excluded after the evaluation of the absorption spectra.

  20. Experimental and theoretical comparison of the O K-edge nonresonant inelastic X-ray scattering and X-ray absorption spectra of NaReO4.

    PubMed

    Bradley, Joseph A; Yang, Ping; Batista, Enrique R; Boland, Kevin S; Burns, Carol J; Clark, David L; Conradson, Steven D; Kozimor, Stosh A; Martin, Richard L; Seidler, Gerald T; Scott, Brian L; Shuh, David K; Tyliszczak, Tolek; Wilkerson, Marianne P; Wolfsberg, Laura E

    2010-10-06

    Accurate X-ray absorption spectra (XAS) of first row atoms, e.g., O, are notoriously difficult to obtain due to the extreme sensitivity of the measurement to surface contamination, self-absorption, and saturation affects. Herein, we describe a comprehensive approach for determining reliable O K-edge XAS data for ReO(4)(1-) and provide methodology for obtaining trustworthy and quantitative data on nonconducting molecular systems, even in the presence of surface contamination. This involves comparing spectra measured by nonresonant inelastic X-ray scattering (NRIXS), a bulk-sensitive technique that is not prone to X-ray self-absorption and provides exact peak intensities, with XAS spectra obtained by three different detection modes, namely total electron yield (TEY), fluorescence yield (FY), and scanning transmission X-ray microscopy (STXM). For ReO(4)(1-), TEY measurements were heavily influenced by surface contamination, while the FY and STXM data agree well with the bulk NRIXS analysis. These spectra all showed two intense pre-edge features indicative of the covalent interaction between the Re 5d and O 2p orbitals. Density functional theory calculations were used to assign these two peaks as O 1s excitations to the e and t(2) molecular orbitals that result from Re 5d and O 2p covalent mixing in T(d) symmetry. Electronic structure calculations were used to determine the amount of O 2p character (%) in these molecular orbitals. Time dependent-density functional theory (TD-DFT) was also used to calculate the energies and intensities of the pre-edge transitions. Overall, under these experimental conditions, this analysis suggests that NRIXS, STXM, and FY operate cooperatively, providing a sound basis for validation of bulk-like excitation spectra and, in combination with electronic structure calculations, suggest that NaReO(4) may serve as a well-defined O K-edge energy and intensity standard for future O K-edge XAS studies.

  1. Deferred slanted-edge analysis: a unified approach to spatial frequency response measurement on distorted images and color filter array subsets.

    PubMed

    van den Bergh, F

    2018-03-01

    The slanted-edge method of spatial frequency response (SFR) measurement is usually applied to grayscale images under the assumption that any distortion of the expected straight edge is negligible. By decoupling the edge orientation and position estimation step from the edge spread function construction step, it is shown in this paper that the slanted-edge method can be extended to allow it to be applied to images suffering from significant geometric distortion, such as produced by equiangular fisheye lenses. This same decoupling also allows the slanted-edge method to be applied directly to Bayer-mosaicked images so that the SFR of the color filter array subsets can be measured directly without the unwanted influence of demosaicking artifacts. Numerical simulation results are presented to demonstrate the efficacy of the proposed deferred slanted-edge method in relation to existing methods.

  2. X-Ray Absorption Near Edge Structure And Extended X-Ray Absorption Fine Structure Analysis of Standards And Biological Samples Containing Mixed Oxidation States of Chromium(III) And Chromium(VI)

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Parsons, J.G.; Dokken, K.; Peralta-Videa, J.R.

    For the first time a method has been developed for the extended X-ray absorption fine structure (EXAFS) data analyses of biological samples containing multiple oxidation states of chromium. In this study, the first shell coordination and interatomic distances based on the data analysis of known standards of potassium chromate (Cr(VI)) and chromium nitrate hexahydrate (Cr(III)) were investigated. The standards examined were mixtures of the following molar ratios of Cr(VI):Cr(III), 0:1, 0.25:0.75, 0.5:0.5, 0.75:0.25, and 1:0. It was determined from the calibration data that the fitting error associated with linear combination X-ray absorption near edge structure (LC-XANES) fittings was approximately {+-}10%more » of the total fitting. The peak height of the Cr(VI) pre-edge feature after normalization of the X-ray absorption (XAS) spectra was used to prepare a calibration curve. The EXAFS fittings of the standards were also investigated and fittings to lechuguilla biomass samples laden with different ratios of Cr(III) and Cr(VI) were performed as well. An excellent agreement between the XANES data and the data presented in the EXAFS spectra was observed. The EXFAS data also presented mean coordination numbers directly related to the ratios of the different chromium oxidation states in the sample. The chromium oxygen interactions had two different bond lengths at approximately 1.68 and 1.98 {angstrom} for the Cr(VI) and Cr(III) in the sample, respectively.« less

  3. Single-scale center-surround Retinex based restoration of low-illumination images with edge enhancement

    NASA Astrophysics Data System (ADS)

    Kwok, Ngaiming; Shi, Haiyan; Peng, Yeping; Wu, Hongkun; Li, Ruowei; Liu, Shilong; Rahman, Md Arifur

    2018-04-01

    Restoring images captured under low-illuminations is an essential front-end process for most image based applications. The Center-Surround Retinex algorithm has been a popular approach employed to improve image brightness. However, this algorithm in its basic form, is known to produce color degradations. In order to mitigate this problem, here the Single-Scale Retinex algorithm is modifid as an edge extractor while illumination is recovered through a non-linear intensity mapping stage. The derived edges are then integrated with the mapped image to produce the enhanced output. Furthermore, in reducing color distortion, the process is conducted in the magnitude sorted domain instead of the conventional Red-Green-Blue (RGB) color channels. Experimental results had shown that improvements with regard to mean brightness, colorfulness, saturation, and information content can be obtained.

  4. Calibrated Multi-Temporal Edge Images for City Infrastructure Growth Assessment and Prediction

    NASA Astrophysics Data System (ADS)

    Al-Ruzouq, R.; Shanableh, A.; Boharoon, Z.; Khalil, M.

    2018-03-01

    Urban Growth or urbanization can be defined as the gradual process of city's population growth and infrastructure development. It is typically demonstrated by the expansion of a city's infrastructure, mainly development of its roads and buildings. Uncontrolled urban Growth in cities has been responsible for several problems that include living environment, drinking water, noise and air pollution, waste management, traffic congestion and hydraulic processes. Accurate identification of urban growth is of great importance for urban planning and water/land management. Recent advances in satellite imagery, in terms of improved spatial and temporal resolutions, allows for efficient identification of change patterns and the prediction of built-up areas. In this study, two approaches were adapted to quantify and assess the pattern of urbanization, in Ajman City at UAE, during the last three decades. The first approach relies on image processing techniques and multi-temporal Landsat satellite images with ground resolution varying between 15 to 60 meters. In this approach, the derived edge images (roads and buildings) were used as the basis of change detection. The second approach relies on digitizing features from high-resolution images captured at different years. The latest approach was adopted, as a reference and ground truth, to calibrate extracted edges from Landsat images. It has been found that urbanized area almost increased by 12 folds during the period 1975-2015 where the growth of buildings and roads were almost parallel until 2005 when the roads spatial expansion witnessed a steep increase due to the vertical expansion of the City. Extracted Edges features, were successfully used for change detection and quantification in term of buildings and roads.

  5. Nickel L-edge and K-edge X-ray absorption spectroscopy of non-innocent Ni[S₂C₂(CF₃)₂]₂(n) series (n = -2, -1, 0): direct probe of nickel fractional oxidation state changes.

    PubMed

    Gu, Weiwei; Wang, Hongxin; Wang, Kun

    2014-05-07

    A series of nickel dithiolene complexes Ni[S2C2(CF3)2]2(n) (n = -2, -1, 0) has been investigated using Ni L- and K-edge X-ray absorption spectroscopy (XAS). The L3 centroid shifts about 0.3 eV for a change of one unit in the formal oxidation state (or 0.3 eV per oxi), corresponding to ~33% of the shift for Ni oxides or fluorides (about 0.9 eV per oxi). The K-edge XAS edge position shifts about 0.7 eV per oxi, corresponding to ~38% of that for Ni oxides (1.85 eV per oxi). In addition, Ni L sum rule analysis found the Ni(3d) ionicity in the frontier orbitals being 50.5%, 44.0% and 38.5% respectively (for n = -2, -1, 0), in comparison with their formal oxidation states (of Ni(II), Ni(III), and Ni(IV)). For the first time, direct and quantitative measurement of the Ni fractional oxidation state changes becomes possible for Ni dithiolene complexes, illustrating the power of L-edge XAS and L sum rule analysis in such a study. The Ni L-edge and K-edge XAS can be used in a complementary manner to better assess the oxidation states for Ni.

  6. Quality optimized medical image information hiding algorithm that employs edge detection and data coding.

    PubMed

    Al-Dmour, Hayat; Al-Ani, Ahmed

    2016-04-01

    The present work has the goal of developing a secure medical imaging information system based on a combined steganography and cryptography technique. It attempts to securely embed patient's confidential information into his/her medical images. The proposed information security scheme conceals coded Electronic Patient Records (EPRs) into medical images in order to protect the EPRs' confidentiality without affecting the image quality and particularly the Region of Interest (ROI), which is essential for diagnosis. The secret EPR data is converted into ciphertext using private symmetric encryption method. Since the Human Visual System (HVS) is less sensitive to alterations in sharp regions compared to uniform regions, a simple edge detection method has been introduced to identify and embed in edge pixels, which will lead to an improved stego image quality. In order to increase the embedding capacity, the algorithm embeds variable number of bits (up to 3) in edge pixels based on the strength of edges. Moreover, to increase the efficiency, two message coding mechanisms have been utilized to enhance the ±1 steganography. The first one, which is based on Hamming code, is simple and fast, while the other which is known as the Syndrome Trellis Code (STC), is more sophisticated as it attempts to find a stego image that is close to the cover image through minimizing the embedding impact. The proposed steganography algorithm embeds the secret data bits into the Region of Non Interest (RONI), where due to its importance; the ROI is preserved from modifications. The experimental results demonstrate that the proposed method can embed large amount of secret data without leaving a noticeable distortion in the output image. The effectiveness of the proposed algorithm is also proven using one of the efficient steganalysis techniques. The proposed medical imaging information system proved to be capable of concealing EPR data and producing imperceptible stego images with minimal

  7. Near Edge X-Ray Absorption and X-Ray Photoelectron Diffraction Studies of the Structural Environment of Ge-Si Systems

    NASA Astrophysics Data System (ADS)

    Castrucci, P.; Gunnella, R.; Pinto, N.; Bernardini, R.; de Crescenzi, M.; Sacchi, M.

    Near edge X-ray absorption spectroscopy (XAS), X-ray photoelectron diffraction (XPD) and Auger electron diffraction (AED) are powerful techniques for the qualitative study of the structural and electronic properties of several systems. The recent development of a multiple scattering approach to simulating experimental spectra opened a friendly way to the study of structural environments of solids and surfaces. This article reviews recent X-ray absorption experiments using synchrotron radiation which were performed at Ge L edges and core level electron diffraction measurements obtained using a traditional X-ray source from Ge core levels for ultrathin Ge films deposited on silicon substrates. Thermodynamics and surface reconstruction have been found to play a crucial role in the first stages of Ge growth on Si(001) and Si(111) surfaces. Both techniques show the occurrence of intermixing processes even for room-temperature-grown Ge/Si(001) samples and give a straightforward measurement of the overlayer tetragonal distortion. The effects of Sb as a surfactant on the Ge/Si(001) interface have also been investigated. In this case, evidence of layer-by-layer growth of the fully strained Ge overlayer with a reduced intermixing is obtained when one monolayer of Sb is predeposited on the surface.

  8. High-resolution molybdenum K-edge X-ray absorption spectroscopy analyzed with time-dependent density functional theory.

    PubMed

    Lima, Frederico A; Bjornsson, Ragnar; Weyhermüller, Thomas; Chandrasekaran, Perumalreddy; Glatzel, Pieter; Neese, Frank; DeBeer, Serena

    2013-12-28

    X-ray absorption spectroscopy (XAS) is a widely used experimental technique capable of selectively probing the local structure around an absorbing atomic species in molecules and materials. When applied to heavy elements, however, the quantitative interpretation can be challenging due to the intrinsic spectral broadening arising from the decrease in the core-hole lifetime. In this work we have used high-energy resolution fluorescence detected XAS (HERFD-XAS) to investigate a series of molybdenum complexes. The sharper spectral features obtained by HERFD-XAS measurements enable a clear assignment of the features present in the pre-edge region. Time-dependent density functional theory (TDDFT) has been previously shown to predict K-pre-edge XAS spectra of first row transition metal compounds with a reasonable degree of accuracy. Here we extend this approach to molybdenum K-edge HERFD-XAS and present the necessary calibration. Modern pure and hybrid functionals are utilized and relativistic effects are accounted for using either the Zeroth Order Regular Approximation (ZORA) or the second order Douglas-Kroll-Hess (DKH2) scalar relativistic approximations. We have found that both the predicted energies and intensities are in excellent agreement with experiment, independent of the functional used. The model chosen to account for relativistic effects also has little impact on the calculated spectra. This study provides an important calibration set for future applications of molybdenum HERFD-XAS to complex catalytic systems.

  9. Image sharpness assessment based on wavelet energy of edge area

    NASA Astrophysics Data System (ADS)

    Li, Jin; Zhang, Hong; Zhang, Lei; Yang, Yifan; He, Lei; Sun, Mingui

    2018-04-01

    Image quality assessment is needed in multiple image processing areas and blur is one of the key reasons of image deterioration. Although great full-reference image quality assessment metrics have been proposed in the past few years, no-reference method is still an area of current research. Facing this problem, this paper proposes a no-reference sharpness assessment method based on wavelet transformation which focuses on the edge area of image. Based on two simple characteristics of human vision system, weights are introduced to calculate weighted log-energy of each wavelet sub band. The final score is given by the ratio of high-frequency energy to the total energy. The algorithm is tested on multiple databases. Comparing with several state-of-the-art metrics, proposed algorithm has better performance and less runtime consumption.

  10. Effect of aluminum on the local structure of silicon in zeolites as studied by Si K edge X-ray absorption near-edge fine structure: spectra simulation with a non-muffin tin atomic background.

    PubMed

    Bugaev, Lusegen A; Bokhoven, Jeroen A van; Khrapko, Valerii V

    2009-04-09

    Experimental Si K edge X-ray absorption near-edge fine structure (XANES) of zeolite faujasite, mordenite, and beta are interpreted by means of the FEFF8 code, replacing the theoretical atomic background mu(0) by a background that was extracted from an experimental spectrum. To some extent, this diminished the effect of the inaccuracy introduced by the MT potential and accounted for the intrinsic loss of photoelectrons. The agreement of the theoretical and experimental spectra at energies above the white lines enabled us to identify structural distortion around silicon, which occurs with increasing aluminum content. The Si K edge XANES spectra are very sensitive to slight distortions in the silicon coordination. Placing an aluminum atom on a nearest neighboring T site causes a distortion in the silicon tetrahedron, shortening one of the silicon-oxygen bonds relative to the other three.

  11. Two-photon absorption and transient photothermal imaging of pigments in tissues

    NASA Astrophysics Data System (ADS)

    Ye, Tong; Fu, Dan; Matthews, Thomas E.; Hong, Lian; Simon, John D.; Warren, Warren S.

    2008-02-01

    As a main pigment in skin tissues, melanin plays an important role in photo-protecting skin from UV radiation. However, melanogenesis may be altered due to disease or environmental factors; for example, sun exposure may cause damage and mutation of melanocytes and induce melanoma. Imaging pigmentation changes may provide invaluable information to catch the malignant transformation in its early stage and in turn improve the prognosis of patients. We have demonstrated previously that transmission mode, two-photon, one- or two-color absorption microscopy could provide remarkable contrast in imaging melanin in skin. In this report we demonstrate significantly improved sensitivity, so that we are now able to image in epi-mode (or back reflection) in two-photon absorption. This improvement makes possible for us to characterize the different types of pigmentation on the skin in vivo at virtually any location. Another finding is that we can also image transient photothermal dynamics due to the light absorption of melanin. By carefully choosing excitation and probe wavelengths, we might be able to image melanin in different structures under different micro-environments in skin, which could provide useful photochemical and photophysical insights in understanding how pigments are involved in photoprotection and photodamage of cells.

  12. Full-Field Calcium K-Edge X-ray Absorption Near-Edge Structure Spectroscopy on Cortical Bone at the Micron-Scale: Polarization Effects Reveal Mineral Orientation.

    PubMed

    Hesse, Bernhard; Salome, Murielle; Castillo-Michel, Hiram; Cotte, Marine; Fayard, Barbara; Sahle, Christoph J; De Nolf, Wout; Hradilova, Jana; Masic, Admir; Kanngießer, Birgit; Bohner, Marc; Varga, Peter; Raum, Kay; Schrof, Susanne

    2016-04-05

    Here, we show results on X-ray absorption near edge structure spectroscopy in both transmission and X-ray fluorescence full-field mode (FF-XANES) at the calcium K-edge on human bone tissue in healthy and diseased conditions and for different tissue maturation stages. We observe that the dominating spectral differences originating from different tissue regions, which are well pronounced in the white line and postedge structures are associated with polarization effects. These polarization effects dominate the spectral variance and must be well understood and modeled before analyzing the very subtle spectral variations related to the bone tissue variations itself. However, these modulations in the fine structure of the spectra can potentially be of high interest to quantify orientations of the apatite crystals in highly structured tissue matrices such as bone. Due to the extremely short wavelengths of X-rays, FF-XANES overcomes the limited spatial resolution of other optical and spectroscopic techniques exploiting visible light. Since the field of view in FF-XANES is rather large the acquisition times for analyzing the same region are short compared to, for example, X-ray diffraction techniques. Our results on the angular absorption dependence were verified by both site-matched polarized Raman spectroscopy, which has been shown to be sensitive to the orientation of bone building blocks and by mathematical simulations of the angular absorbance dependence. As an outlook we further demonstrate the polarization based assessment of calcium-containing crystal orientation and specification of calcium in a beta-tricalcium phosphate (β-Ca3(PO4)2 scaffold implanted into ovine bone. Regarding the use of XANES to assess chemical properties of Ca in human bone tissue our data suggest that neither the anatomical site (tibia vs jaw) nor pathology (healthy vs necrotic jaw bone tissue) affected the averaged spectral shape of the XANES spectra.

  13. A search for the iron absorption edge in the tail of an X-ray burst from X1636 - 53

    NASA Astrophysics Data System (ADS)

    Day, C. S. R.; Fabian, A. C.; Ross, R. R.

    1992-08-01

    Model atmosphere calculations of the spectrum of a neutron star cooling after an X-ray burst show that the photoelectric edge of iron should be prominent. No clear evidence for such a redshifted feature in the spectrum of a burst from X1636 - 53 is found, and it is concluded that the iron abundance there must be less than 0.3 solar. Unless the iron abundance of the surface matter on the neutron star is highly time-dependent, the present result argues against the 4.1-keV absorption line seen in some bursts from X1636 - 53 by Waki et al. (1984) being due to iron. The iron edge will be a powerful diagnostic of the surface redshift of the neutron star in burst sources where the iron abundance is more nearly solar.

  14. A search for the iron absorption edge in the tail of an X-ray burst from X1636 - 53

    NASA Technical Reports Server (NTRS)

    Day, C. S. R.; Fabian, A. C.; Ross, R. R.

    1992-01-01

    Model atmosphere calculations of the spectrum of a neutron star cooling after an X-ray burst show that the photoelectric edge of iron should be prominent. No clear evidence for such a redshifted feature in the spectrum of a burst from X1636 - 53 is found, and it is concluded that the iron abundance there must be less than 0.3 solar. Unless the iron abundance of the surface matter on the neutron star is highly time-dependent, the present result argues against the 4.1-keV absorption line seen in some bursts from X1636 - 53 by Waki et al. (1984) being due to iron. The iron edge will be a powerful diagnostic of the surface redshift of the neutron star in burst sources where the iron abundance is more nearly solar.

  15. Speciation of sulfur from filamentous microbial mats from sulfidic cave springs using X-ray absorption near-edge spectroscopy.

    PubMed

    Engel, Annette Summers; Lichtenberg, Henning; Prange, Alexander; Hormes, Josef

    2007-04-01

    Most transformations within the sulfur cycle are controlled by the biosphere, and deciphering the abiotic and biotic nature and turnover of sulfur is critical to understand the geochemical and ecological changes that have occurred throughout the Earth's history. Here, synchrotron radiation-based sulfur K-edge X-ray absorption near-edge structure (XANES) spectroscopy is used to examine sulfur speciation in natural microbial mats from two aphotic (cave) settings. Habitat geochemistry, microbial community compositions, and sulfur isotope systematics were also evaluated. Microorganisms associated with sulfur metabolism dominated the mats, including members of the Epsilonproteobacteria and Gammaproteobacteria. These groups have not been examined previously by sulfur K-edge XANES. All of the mats consisted of elemental sulfur, with greater contributions of cyclo-octasulfur (S8) compared with polymeric sulfur (Smicro). While this could be a biological fingerprint for some bacteria, the signature may also indicate preferential oxidation of Smicro and S8 accumulation. Higher sulfate content correlated to less S8 in the presence of Epsilonproteobacteria. Sulfur isotope compositions confirmed that sulfur content and sulfur speciation may not correlate to microbial metabolic processes in natural samples, thereby complicating the interpretation of modern and ancient sulfur records.

  16. Kα X-Ray Emission Spectra and K X-Ray Absorption-Edge Structures of Fluorine in 3d Transition-Metal Difluorides

    NASA Astrophysics Data System (ADS)

    Sugiura, Chikara

    1991-08-01

    The fluorine Kα emission spectra in fluorescence from a series of 3d transition-metal difluorides MF2 (M=Mn, Fe, Co, Ni, Cu and Zn) have been measured with a high-resolution two-crystal vacuum spectrometer. It is shown that the observed FWHM of the Kα1,2 emission band is closely related to the difference in the electronegativity between the metal and fluorine atoms. The measured emission spectra are presented along with the UPS or XPS spectra of the valence bands and the fluorine K absorption spectra of the metal difluorides, reported previously. The structures at the fluorine K absorption edges are interpreted in terms of a molecular orbital (MO) model.

  17. Edge enhancement and image equalization by unsharp masking using self-adaptive photochromic filters.

    PubMed

    Ferrari, José A; Flores, Jorge L; Perciante, César D; Frins, Erna

    2009-07-01

    A new method for real-time edge enhancement and image equalization using photochromic filters is presented. The reversible self-adaptive capacity of photochromic materials is used for creating an unsharp mask of the original image. This unsharp mask produces a kind of self filtering of the original image. Unlike the usual Fourier (coherent) image processing, the technique we propose can also be used with incoherent illumination. Validation experiments with Bacteriorhodopsin and photochromic glass are presented.

  18. In Situ X-ray Absorption Near-Edge Structure Spectroscopy of ZnO Nanowire Growth During Chemical Bath Deposition

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    McPeak, Kevin M.; Becker, Matthew A.; Britton, Nathan G.

    2010-12-03

    Chemical bath deposition (CBD) offers a simple and inexpensive route to deposit semiconductor nanostructures, but lack of fundamental understanding and control of the underlying chemistry has limited its versatility. Here we report the first use of in situ X-ray absorption spectroscopy during CBD, enabling detailed investigation of both reaction mechanisms and kinetics of ZnO nanowire growth from zinc nitrate and hexamethylenetetramine (HMTA) precursors. Time-resolved X-ray absorption near-edge structure (XANES) spectra were used to quantify Zn(II) speciation in both solution and solid phases. ZnO crystallizes directly from [Zn(H{sub 2}O){sub 6}]{sup 2+} without long-lived intermediates. Using ZnO nanowire deposition as an example,more » this study establishes in situ XANES spectroscopy as an excellent quantitative tool to understand CBD of nanomaterials.« less

  19. Integration of adaptive guided filtering, deep feature learning, and edge-detection techniques for hyperspectral image classification

    NASA Astrophysics Data System (ADS)

    Wan, Xiaoqing; Zhao, Chunhui; Gao, Bing

    2017-11-01

    The integration of an edge-preserving filtering technique in the classification of a hyperspectral image (HSI) has been proven effective in enhancing classification performance. This paper proposes an ensemble strategy for HSI classification using an edge-preserving filter along with a deep learning model and edge detection. First, an adaptive guided filter is applied to the original HSI to reduce the noise in degraded images and to extract powerful spectral-spatial features. Second, the extracted features are fed as input to a stacked sparse autoencoder to adaptively exploit more invariant and deep feature representations; then, a random forest classifier is applied to fine-tune the entire pretrained network and determine the classification output. Third, a Prewitt compass operator is further performed on the HSI to extract the edges of the first principal component after dimension reduction. Moreover, the regional growth rule is applied to the resulting edge logical image to determine the local region for each unlabeled pixel. Finally, the categories of the corresponding neighborhood samples are determined in the original classification map; then, the major voting mechanism is implemented to generate the final output. Extensive experiments proved that the proposed method achieves competitive performance compared with several traditional approaches.

  20. NO binding kinetics in myoglobin investigated by picosecond Fe K-edge absorption spectroscopy

    PubMed Central

    Silatani, Mahsa; Lima, Frederico A.; Penfold, Thomas J.; Rittmann, Jochen; Reinhard, Marco E.; Rittmann-Frank, Hannelore M.; Borca, Camelia; Grolimund, Daniel; Milne, Christopher J.; Chergui, Majed

    2015-01-01

    Diatomic ligands in hemoproteins and the way they bind to the active center are central to the protein’s function. Using picosecond Fe K-edge X-ray absorption spectroscopy, we probe the NO-heme recombination kinetics with direct sensitivity to the Fe-NO binding after 532-nm photoexcitation of nitrosylmyoglobin (MbNO) in physiological solutions. The transients at 70 and 300 ps are identical, but they deviate from the difference between the static spectra of deoxymyoglobin and MbNO, showing the formation of an intermediate species. We propose the latter to be a six-coordinated domed species that is populated on a timescale of ∼200 ps by recombination with NO ligands. This work shows the feasibility of ultrafast pump–probe X-ray spectroscopic studies of proteins in physiological media, delivering insight into the electronic and geometric structure of the active center. PMID:26438842

  1. Quantum Monte Carlo for the x-ray absorption spectrum of pyrrole at the nitrogen K-edge

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zubarev, Dmitry Yu.; Austin, Brian M.; Lester, William A. Jr.

    Fixed-node diffusion Monte Carlo (FNDMC) is used to simulate the x-ray absorption spectrum of a gas-phase pyrrole molecule at the nitrogen K-edge. Trial wave functions for core-excited states are constructed from ground-state Kohn-Sham determinants substituted with singly occupied natural orbitals from configuration interaction with single excitations calculations of the five lowest valence-excited triplet states. The FNDMC ionization potential (IP) is found to lie within 0.3 eV of the experimental value of 406.1 {+-} 0.1 eV. The transition energies to anti-bonding virtual orbitals match the experimental spectrum after alignment of IP values and agree with the existing assignments.

  2. Changes in the near edge X-ray absorption fine structure of hybrid organic-inorganic resists upon exposure.

    PubMed

    Fallica, Roberto; Watts, Benjamin; Roesner, Benedikt; Della Giustina, Gioia; Brigo, Laura; Brusatin, Giovanna; Ekinci, Yasin

    2018-06-14

    We report on the near edge X-ray absorption fine structure (NEXAFS) spectroscopy of hybrid organic-inorganic resists. These materials are nonchemically amplified systems based on Si, Zr, and Ti oxides, synthesized from organically modified precursors and transition metal alkoxides by a sol-gel route and designed for ultraviolet, extreme ultraviolet and electron beam lithography. The experiments were conducted using a scanning transmission X-ray microscope (STXM) which combines high spatial-resolution microscopy and NEXAFS spectroscopy. The absorption spectra were collected in the proximity of the carbon edge (~ 290 eV) before and after in situ exposure, enabling the measurement of a significant photo-induced degradation of the organic group (phenyl or methyl methacrylate, respectively), the degree of which depends on the configuration of the ligand. Photo-induced degradation was more efficient in the resist synthesized with pendant phenyl substituents than it was in the case of systems based on bridging phenyl groups. The degradation of the methyl methacrylate group was relatively efficient, with about half of the initial ligands dissociated upon exposure. Our data reveal that the such dissociation can produce different outcomes, depending on the structural configuration. While all the organic groups were expected to detach and desorb from the resist in their entirety, a sizeable amount of them remain and form undesired byproducts such as alkene chains. In the framework of the materials synthesis and engineering through specific building blocks, these results provide a deeper insight into the photochemistry of resists, in particular for extreme ultraviolet lithography. © 2018 IOP Publishing Ltd.

  3. Molybdenum X-Ray Absorption Edges from 200 – 20,000 eV, The Benefits of Soft X-Ray Spectroscopy for Chemical Speciation

    PubMed Central

    George, Simon J.; Drury, Owen B.; Fu, Juxia; Friedrich, Stephan; Doonan, Christian J.; George, Graham N.; White, Jonathan M.; Young, Charles G.; Cramer, Stephen P.

    2009-01-01

    We have surveyed the chemical utility of the near-edge structure of molybdenum x-ray absorption edges from the hard x-ray K-edge at 20,000 eV down to the soft x-ray M4,5-edges at ~230 eV. We compared, for each edge, the spectra of two tetrahedral anions, MoO4 and MoS42-. We used three criteria for assessing near-edge structure of each edge: (i) the ratio of the observed chemical shift between MoO42- and MoS42- and the linewidth, (ii) the chemical information from analysis of the near-edge structure and (iii) the ease of measurement using fluorescence detection. Not surprisingly, the K-edge was by far the easiest to measure, but it contained the least information. The L2,3-edges, although harder to measure, had benefits with regard to selection rules and chemical speciation in that they had both a greater chemical shift as well as detailed lineshapes which could be theoretically analyzed in terms of Mo ligand field, symmetry, and covalency. The soft x-ray M2,3-edges were perhaps the least useful, in that they were difficult to measure using fluorescence detection and had very similar information content to the corresponding L2,3-edges. Interestingly, the soft x-ray, low energy (~230 eV) M4,5-edges had greatest potential chemical sensitivity and using our high resolution superconducting tunnel junction (STJ) fluorescence detector they appear to be straightforward to measure. The spectra were amenable to analysis using both the TT-multiplet approach and FEFF. The results using FEFF indicate that the sharp near-edge peaks arise from 3d → 5p transitions, while the broad edge structure has predominately 3d → 4f character. A proper understanding of the dependence of these soft x-ray spectra on ligand field and site geometry is necessary before a complete assessment of the utility of the Mo M4,5-edges can be made. This work includes crystallographic characterization of sodium tetrathiomolybdate. PMID:19041140

  4. K-edge ratio method for identification of multiple nanoparticulate contrast agents by spectral CT imaging

    PubMed Central

    Ghadiri, H; Ay, M R; Shiran, M B; Soltanian-Zadeh, H

    2013-01-01

    Objective: Recently introduced energy-sensitive X-ray CT makes it feasible to discriminate different nanoparticulate contrast materials. The purpose of this work is to present a K-edge ratio method for differentiating multiple simultaneous contrast agents using spectral CT. Methods: The ratio of two images relevant to energy bins straddling the K-edge of the materials is calculated using an analytic CT simulator. In the resulting parametric map, the selected contrast agent regions can be identified using a thresholding algorithm. The K-edge ratio algorithm is applied to spectral images of simulated phantoms to identify and differentiate up to four simultaneous and targeted CT contrast agents. Results: We show that different combinations of simultaneous CT contrast agents can be identified by the proposed K-edge ratio method when energy-sensitive CT is used. In the K-edge parametric maps, the pixel values for biological tissues and contrast agents reach a maximum of 0.95, whereas for the selected contrast agents, the pixel values are larger than 1.10. The number of contrast agents that can be discriminated is limited owing to photon starvation. For reliable material discrimination, minimum photon counts corresponding to 140 kVp, 100 mAs and 5-mm slice thickness must be used. Conclusion: The proposed K-edge ratio method is a straightforward and fast method for identification and discrimination of multiple simultaneous CT contrast agents. Advances in knowledge: A new spectral CT-based algorithm is proposed which provides a new concept of molecular CT imaging by non-iteratively identifying multiple contrast agents when they are simultaneously targeting different organs. PMID:23934964

  5. Error of the slanted edge method for measuring the modulation transfer function of imaging systems.

    PubMed

    Xie, Xufen; Fan, Hongda; Wang, Hongyuan; Wang, Zebin; Zou, Nianyu

    2018-03-01

    The slanted edge method is a basic approach for measuring the modulation transfer function (MTF) of imaging systems; however, its measurement accuracy is limited in practice. Theoretical analysis of the slanted edge MTF measurement method performed in this paper reveals that inappropriate edge angles and random noise reduce this accuracy. The error caused by edge angles is analyzed using sampling and reconstruction theory. Furthermore, an error model combining noise and edge angles is proposed. We verify the analyses and model with respect to (i) the edge angle, (ii) a statistical analysis of the measurement error, (iii) the full width at half-maximum of a point spread function, and (iv) the error model. The experimental results verify the theoretical findings. This research can be referential for applications of the slanted edge MTF measurement method.

  6. Silicon K-edge XANES spectra of silicate minerals

    NASA Astrophysics Data System (ADS)

    Li, Dien; Bancroft, G. M.; Fleet, M. E.; Feng, X. H.

    1995-03-01

    Silicon K-edge x-ray absorption near-edge structure (XANES) spectra of a selection of silicate and aluminosilicate minerals have been measured using synchrotron radiation (SR). The spectra are qualitatively interpreted based on MO calculation of the tetrahedral SiO{4/4-}cluster. The Si K-edge generally shifts to higher energy with increased polymerization of silicates by about 1.3 eV, but with considerable overlap for silicates of different polymerization types. The substitution of Al for Si shifts the Si K-edge to lower energy. The chemical shift of Si K-edge is also sensitive to cations in more distant atom shells; for example, the Si K-edge shifts to lower energy with the substitution of Al for Mg in octahedral sites. The shifts of the Si K-edge show weak correlation with average Si-O bond distance (dSi-O), Si-O bond valence (sSi-O) and distortion of SiO4 tetrahedra, due to the crystal structure complexity of silicate minerals and multiple factors effecting the x-ray absorption processes.

  7. Extended x-ray absorption fine structure spectroscopy and x-ray absorption near edge spectroscopy study of aliovalent doped ceria to correlate local structural changes with oxygen vacancies clustering

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Shirbhate, S. C.; Acharya, S. A., E-mail: saha275@yahoo.com; Yadav, A. K.

    2016-04-04

    This study provides atomic scale insight to understand the role of aliovalent dopants on oxygen vacancies clustering and dissociation mechanism in ceria system in order to enhance the performance of oxy-ion conductor. Dopants induced microscale changes in ceria are probed by extended X-ray absorption fine structure spectroscopy, X-ray absorption near edge spectra, and Raman spectroscopy. The results are explored to establish a correlation between atomic level structural changes (coordination number, interatomic spacing) → formation of dimer and trimer type cation-oxygen vacancies defect complex (intrinsic and extrinsic) → dissociation of oxygen vacancies from defect cluster → ionic conductivity temperature. It ismore » a strategic approach to understand key physics of ionic conductivity mechanism in order to reduce operating temperature of electrolytes for intermediate temperature (300–450 °C) electrochemical devices for the first time.« less

  8. High quality image-pair-based deblurring method using edge mask and improved residual deconvolution

    NASA Astrophysics Data System (ADS)

    Cui, Guangmang; Zhao, Jufeng; Gao, Xiumin; Feng, Huajun; Chen, Yueting

    2017-04-01

    Image deconvolution problem is a challenging task in the field of image process. Using image pairs could be helpful to provide a better restored image compared with the deblurring method from a single blurred image. In this paper, a high quality image-pair-based deblurring method is presented using the improved RL algorithm and the gain-controlled residual deconvolution technique. The input image pair includes a non-blurred noisy image and a blurred image captured for the same scene. With the estimated blur kernel, an improved RL deblurring method based on edge mask is introduced to obtain the preliminary deblurring result with effective ringing suppression and detail preservation. Then the preliminary deblurring result is served as the basic latent image and the gain-controlled residual deconvolution is utilized to recover the residual image. A saliency weight map is computed as the gain map to further control the ringing effects around the edge areas in the residual deconvolution process. The final deblurring result is obtained by adding the preliminary deblurring result with the recovered residual image. An optical experimental vibration platform is set up to verify the applicability and performance of the proposed algorithm. Experimental results demonstrate that the proposed deblurring framework obtains a superior performance in both subjective and objective assessments and has a wide application in many image deblurring fields.

  9. High energy X-ray phase and dark-field imaging using a random absorption mask.

    PubMed

    Wang, Hongchang; Kashyap, Yogesh; Cai, Biao; Sawhney, Kawal

    2016-07-28

    High energy X-ray imaging has unique advantage over conventional X-ray imaging, since it enables higher penetration into materials with significantly reduced radiation damage. However, the absorption contrast in high energy region is considerably low due to the reduced X-ray absorption cross section for most materials. Even though the X-ray phase and dark-field imaging techniques can provide substantially increased contrast and complementary information, fabricating dedicated optics for high energies still remain a challenge. To address this issue, we present an alternative X-ray imaging approach to produce transmission, phase and scattering signals at high X-ray energies by using a random absorption mask. Importantly, in addition to the synchrotron radiation source, this approach has been demonstrated for practical imaging application with a laboratory-based microfocus X-ray source. This new imaging method could be potentially useful for studying thick samples or heavy materials for advanced research in materials science.

  10. Far-field optical imaging with subdiffraction resolution enabled by nonlinear saturation absorption

    NASA Astrophysics Data System (ADS)

    Ding, Chenliang; Wei, Jingsong

    2016-01-01

    The resolution of far-field optical imaging is required to improve beyond the Abbe limit to the subdiffraction or even the nanoscale. In this work, inspired by scanning electronic microscopy (SEM) imaging, in which carbon (or Au) thin films are usually required to be coated on the sample surface before imaging to remove the charging effect while imaging by electrons. We propose a saturation-absorption-induced far-field super-resolution optical imaging method (SAI-SRIM). In the SAI-SRIM, the carbon (or Au) layers in SEM imaging are replaced by nonlinear-saturation-absorption (NSA) thin films, which are directly coated onto the sample surfaces using advanced thin film deposition techniques. The surface fluctuant morphologies are replicated to the NSA thin films, accordingly. The coated sample surfaces are then imaged using conventional laser scanning microscopy. Consequently, the imaging resolution is greatly improved, and subdiffraction-resolved optical images are obtained theoretically and experimentally. The SAI-SRIM provides an effective and easy way to achieve far-field super-resolution optical imaging for sample surfaces with geometric fluctuant morphology characteristics.

  11. Edge-directed inference for microaneurysms detection in digital fundus images

    NASA Astrophysics Data System (ADS)

    Huang, Ke; Yan, Michelle; Aviyente, Selin

    2007-03-01

    Microaneurysms (MAs) detection is a critical step in diabetic retinopathy screening, since MAs are the earliest visible warning of potential future problems. A variety of algorithms have been proposed for MAs detection in mass screening. Different methods have been proposed for MAs detection. The core technology for most of existing methods is based on a directional mathematical morphological operation called "Top-Hat" filter that requires multiple filtering operations at each pixel. Background structure, uneven illumination and noise often cause confusion between MAs and some non-MA structures and limits the applicability of the filter. In this paper, a novel detection framework based on edge directed inference is proposed for MAs detection. The candidate MA regions are first delineated from the edge map of a fundus image. Features measuring shape, brightness and contrast are extracted for each candidate MA region to better exclude false detection from true MAs. Algorithmic analysis and empirical evaluation reveal that the proposed edge directed inference outperforms the "Top-Hat" based algorithm in both detection accuracy and computational speed.

  12. Quantum simulation of thermally-driven phase transition and oxygen K-edge x-ray absorption of high-pressure ice

    PubMed Central

    Kang, Dongdong; Dai, Jiayu; Sun, Huayang; Hou, Yong; Yuan, Jianmin

    2013-01-01

    The structure and phase transition of high-pressure ice are of long-standing interest and challenge, and there is still a huge gap between theoretical and experimental understanding. The quantum nature of protons such as delocalization, quantum tunneling and zero-point motion is crucial to the comprehension of the properties of high-pressure ice. Here we investigated the temperature-induced phase transition and oxygen K-edge x-ray absorption spectra of ice VII, VIII and X using ab initio path-integral molecular dynamics simulations. The tremendous difference between experiments and the previous theoretical predictions is closed for the phase diagram of ice below 300 K at pressures up to 110 GPa. Proton tunneling assists the proton-ordered ice VIII to transform into proton-disordered ice VII where only thermal activated proton-transfer cannot occur. The oxygen K edge with its shift is sensitive to the order-disorder transition, and therefore can be applied to diagnose the dynamics of ice structures. PMID:24253589

  13. Identification of B-K near edge x-ray absorption fine structure peaks of boron nitride thin films prepared by sputtering deposition

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Niibe, Masahito; Miyamoto, Kazuyoshi; Mitamura, Tohru

    2010-09-15

    Four {pi}{sup *} resonance peaks were observed in the B-K near edge x-ray absorption fine structure spectra of boron nitride thin films prepared by magnetron sputtering. In the past, these peaks have been explained as the K-absorption of boron atoms, which are present in environment containing nitrogen vacancies, the number of which is 1-3 corresponding to the three peaks at higher photon energy. However, the authors found that there was a strong correlation between the intensities of these three peaks and that of O-K absorption after wide range scanning and simultaneous measurement of nitrogen and oxygen K-absorptions of the BNmore » films. Therefore, the authors conclude that these three peaks at the higher energy side correspond to boron atoms bound to one-to-three oxygen atoms instead of three nitrogen atoms surrounding the boron atom in the h-BN structure. The result of the first-principles calculation with a simple cluster model supported the validity of this explanation.« less

  14. X-ray absorption near-edge structure micro-spectroscopy study of vanadium speciation in Phycomyces blakesleeanus mycelium.

    PubMed

    Žižić, Milan; Dučić, Tanja; Grolimund, Daniel; Bajuk-Bogdanović, Danica; Nikolic, Miroslav; Stanić, Marina; Križak, Strahinja; Zakrzewska, Joanna

    2015-09-01

    Vanadium speciation in the fungus Phycomyces blakesleeanus was examined by X-ray absorption near-edge structure (XANES) spectroscopy, enabling assessment of oxidation states and related molecular symmetries of this transition element in the fungus. The exposure of P. blakesleeanus to two physiologically important vanadium species (V(5+) and V(4+)) resulted in the accumulation of this metal in central compartments of 24 h old mycelia, most probably in vacuoles. Tetrahedral V(5+), octahedral V(4+), and proposed intracellular complexes of V(5+) were detected simultaneously after addition of a physiologically relevant concentration of V(5+) to the mycelium. A substantial fraction of the externally added V(4+) remained mostly in its original form. However, observable variations in the pre-edge-peak intensities in the XANES spectra indicated intracellular complexation and corresponding changes in the molecular coordination symmetry. Vanadate complexation was confirmed by (51)V NMR and Raman spectroscopy, and potential binding compounds including cell-wall constituents (chitosan and/or chitin), (poly)phosphates, DNA, and proteins are proposed. The evidenced vanadate complexation and reduction could also explain the resistance of P. blakesleeanus to high extracellular concentrations of vanadium.

  15. Three-dimensional labeling of newly formed bone using synchrotron radiation barium K-edge subtraction imaging

    NASA Astrophysics Data System (ADS)

    Panahifar, Arash; Swanston, Treena M.; Pushie, M. Jake; Belev, George; Chapman, Dean; Weber, Lynn; Cooper, David M. L.

    2016-07-01

    Bone is a dynamic tissue which exhibits complex patterns of growth as well as continuous internal turnover (i.e. remodeling). Tracking such changes can be challenging and thus a high resolution imaging-based tracer would provide a powerful new perspective on bone tissue dynamics. This is, particularly so if such a tracer can be detected in 3D. Previously, strontium has been demonstrated to be an effective tracer which can be detected by synchrotron-based dual energy K-edge subtraction (KES) imaging in either 2D or 3D. The use of strontium is, however, limited to very small sample thicknesses due to its low K-edge energy (16.105 keV) and thus is not suitable for in vivo application. Here we establish proof-of-principle for the use of barium as an alternative tracer with a higher K-edge energy (37.441 keV), albeit for ex vivo imaging at the moment, which enables application in larger specimens and has the potential to be developed for in vivo imaging of preclinical animal models. New bone formation within growing rats in 2D and 3D was demonstrated at the Biomedical Imaging and Therapy bending magnet (BMIT-BM) beamline of the Canadian Light Source synchrotron. Comparative x-ray fluorescence imaging confirmed those patterns of uptake detected by KES. This initial work provides a platform for the further development of this tracer and its exploration of applications for in vivo development.

  16. Examination of the Measurement of Absorption Using the Reverberant Room Method for Highly Absorptive Acoustic Foam

    NASA Technical Reports Server (NTRS)

    Hughes, William O.; McNelis, Anne M.; Chris Nottoli; Eric Wolfram

    2015-01-01

    The absorption coefficient for material specimens are needed to quantify the expected acoustic performance of that material in its actual usage and environment. The ASTM C423-09a standard, "Standard Test Method for Sound Absorption and Sound Absorption Coefficients by the Reverberant Room Method" is often used to measure the absorption coefficient of material test specimens. This method has its basics in the Sabine formula. Although widely used, the interpretation of these measurements are a topic of interest. For example, in certain cases the measured Sabine absorption coefficients are greater than 1.0 for highly absorptive materials. This is often attributed to the diffraction edge effect phenomenon. An investigative test program to measure the absorption properties of highly absorbent melamine foam has been performed at the Riverbank Acoustical Laboratories. This paper will present and discuss the test results relating to the effect of the test materials' surface area, thickness and edge sealing conditions. A follow-on paper is envisioned that will present and discuss the results relating to the spacing between multiple piece specimens, and the mounting condition of the test specimen.

  17. Electronic structure and optical properties of CdSxSe1-x solid solution nanostructures from X-ray absorption near edge structure, X-ray excited optical luminescence, and density functional theory investigations

    NASA Astrophysics Data System (ADS)

    Murphy, M. W.; Yiu, Y. M.; Ward, M. J.; Liu, L.; Hu, Y.; Zapien, J. A.; Liu, Yingkai; Sham, T. K.

    2014-11-01

    The electronic structure and optical properties of a series of iso-electronic and iso-structural CdSxSe1-x solid solution nanostructures have been investigated using X-ray absorption near edge structure, extended X-ray absorption fine structure, and X-ray excited optical luminescence at various absorption edges of Cd, S, and Se. It is found that the system exhibits compositions, with variable local structure in-between that of CdS and CdSe accompanied by tunable optical band gap between that of CdS and CdSe. Theoretical calculation using density functional theory has been carried out to elucidate the observations. It is also found that luminescence induced by X-ray excitation shows new optical channels not observed previously with laser excitation. The implications of these observations are discussed.

  18. Subpixel edge estimation with lens aberrations compensation based on the iterative image approximation for high-precision thermal expansion measurements of solids

    NASA Astrophysics Data System (ADS)

    Inochkin, F. M.; Kruglov, S. K.; Bronshtein, I. G.; Kompan, T. A.; Kondratjev, S. V.; Korenev, A. S.; Pukhov, N. F.

    2017-06-01

    A new method for precise subpixel edge estimation is presented. The principle of the method is the iterative image approximation in 2D with subpixel accuracy until the appropriate simulated is found, matching the simulated and acquired images. A numerical image model is presented consisting of three parts: an edge model, object and background brightness distribution model, lens aberrations model including diffraction. The optimal values of model parameters are determined by means of conjugate-gradient numerical optimization of a merit function corresponding to the L2 distance between acquired and simulated images. Computationally-effective procedure for the merit function calculation along with sufficient gradient approximation is described. Subpixel-accuracy image simulation is performed in a Fourier domain with theoretically unlimited precision of edge points location. The method is capable of compensating lens aberrations and obtaining the edge information with increased resolution. Experimental method verification with digital micromirror device applied to physically simulate an object with known edge geometry is shown. Experimental results for various high-temperature materials within the temperature range of 1000°C..2400°C are presented.

  19. Orientational behavior of thin films of poly(3-methylthiophene) on platinium: A FTIR and near edge x-ray absorption fine structure (NEXAFS) study

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Yang, X.Q.; Chen, J.; Hale, P.D.

    1988-01-01

    Near edge x-ray absorption fine structure (NEXAFS) and infrared reflection-absorption spectroscopy (IRRAS) have been used to study the orientational behavior of thin films of poly(3-methylthiophene) electrochemically polymerized on a platinum surface. Clear orientational effects, with the thiophene rings predominantly oriented parallel to the platinum surface, were observed when the thickness of the polymer films were within a few hundred /angstrom/A. It was found that more highly ordered films were produced at lower polymerization potential (1.4V vs SCE) than at higher potential (1.8V vs SCE). 5 refs., 4 figs., 2 tabs.

  20. Segmentation of prostate from ultrasound images using level sets on active band and intensity variation across edges.

    PubMed

    Li, Xu; Li, Chunming; Fedorov, Andriy; Kapur, Tina; Yang, Xiaoping

    2016-06-01

    In this paper, the authors propose a novel efficient method to segment ultrasound images of the prostate with weak boundaries. Segmentation of the prostate from ultrasound images with weak boundaries widely exists in clinical applications. One of the most typical examples is the diagnosis and treatment of prostate cancer. Accurate segmentation of the prostate boundaries from ultrasound images plays an important role in many prostate-related applications such as the accurate placement of the biopsy needles, the assignment of the appropriate therapy in cancer treatment, and the measurement of the prostate volume. Ultrasound images of the prostate are usually corrupted with intensity inhomogeneities, weak boundaries, and unwanted edges, which make the segmentation of the prostate an inherently difficult task. Regarding to these difficulties, the authors introduce an active band term and an edge descriptor term in the modified level set energy functional. The active band term is to deal with intensity inhomogeneities and the edge descriptor term is to capture the weak boundaries or to rule out unwanted boundaries. The level set function of the proposed model is updated in a band region around the zero level set which the authors call it an active band. The active band restricts the authors' method to utilize the local image information in a banded region around the prostate contour. Compared to traditional level set methods, the average intensities inside∖outside the zero level set are only computed in this banded region. Thus, only pixels in the active band have influence on the evolution of the level set. For weak boundaries, they are hard to be distinguished by human eyes, but in local patches in the band region around prostate boundaries, they are easier to be detected. The authors incorporate an edge descriptor to calculate the total intensity variation in a local patch paralleled to the normal direction of the zero level set, which can detect weak boundaries

  1. Segmentation of prostate from ultrasound images using level sets on active band and intensity variation across edges

    PubMed Central

    Li, Xu; Li, Chunming; Fedorov, Andriy; Kapur, Tina; Yang, Xiaoping

    2016-01-01

    Purpose: In this paper, the authors propose a novel efficient method to segment ultrasound images of the prostate with weak boundaries. Segmentation of the prostate from ultrasound images with weak boundaries widely exists in clinical applications. One of the most typical examples is the diagnosis and treatment of prostate cancer. Accurate segmentation of the prostate boundaries from ultrasound images plays an important role in many prostate-related applications such as the accurate placement of the biopsy needles, the assignment of the appropriate therapy in cancer treatment, and the measurement of the prostate volume. Methods: Ultrasound images of the prostate are usually corrupted with intensity inhomogeneities, weak boundaries, and unwanted edges, which make the segmentation of the prostate an inherently difficult task. Regarding to these difficulties, the authors introduce an active band term and an edge descriptor term in the modified level set energy functional. The active band term is to deal with intensity inhomogeneities and the edge descriptor term is to capture the weak boundaries or to rule out unwanted boundaries. The level set function of the proposed model is updated in a band region around the zero level set which the authors call it an active band. The active band restricts the authors’ method to utilize the local image information in a banded region around the prostate contour. Compared to traditional level set methods, the average intensities inside∖outside the zero level set are only computed in this banded region. Thus, only pixels in the active band have influence on the evolution of the level set. For weak boundaries, they are hard to be distinguished by human eyes, but in local patches in the band region around prostate boundaries, they are easier to be detected. The authors incorporate an edge descriptor to calculate the total intensity variation in a local patch paralleled to the normal direction of the zero level set, which can

  2. Fabrication of absorption gratings with X-ray lithography for X-ray phase contrast imaging

    NASA Astrophysics Data System (ADS)

    Wang, Bo; Wang, Yu-Ting; Yi, Fu-Ting; Zhang, Tian-Chong; Liu, Jing; Zhou, Yue

    2018-05-01

    Grating-based X-ray phase contrast imaging is promising especially in the medical area. Two or three gratings are involved in grating-based X-ray phase contrast imaging in which the absorption grating of high-aspect-ratio is the most important device and the fabrication process is a great challenge. The material with large atomic number Z is used to fabricate the absorption grating for excellent absorption of X-ray, and Au is usually used. The fabrication process, which involves X-ray lithography, development and gold electroplating, is described in this paper. The absorption gratings with 4 μm period and about 100 μm height are fabricated and the high-aspect-ratio is 50.

  3. Electronic structure of Cr doped Fe3O4 thin films by X-ray absorption near-edge structure spectroscopy

    NASA Astrophysics Data System (ADS)

    Chen, Chi-Liang; Dong, Chung-Li; Asokan, Kandasami; Chern, G.; Chang, C. L.

    2018-04-01

    Present study reports the electronic structures of Cr doped Fe3O4 (Fe3-xCrxO4 (0 ≤ x ≤ 3) grown on MgO (100) substrates in the form of thin films fabricated by a plasma-oxygen assisted Molecular Beam Epitaxy (MBE). X-ray absorption near-edge structure (XANES) spectra at Cr & Fe L-, and O K-edges were used to understand the electronic structure: changes in the bonding nature, valence states, and site occupancies. Cr doping in Fe3O4 results in the change of charge transfer, crystal structure, and selective occupation of ions in octahedral and tetrahedral sites. Such change modifies the electrical and magnetic properties due to the covalency of Cr ions. The physical and chemical properties of ferrites are strongly dependent on the lattice site, ion size of dopant, and magnetic nature present at different structural symmetry of the spinel structure.

  4. Scanning imaging absorption spectrometer for atmospheric chartography

    NASA Technical Reports Server (NTRS)

    Burrows, John P.; Chance, Kelly V.

    1991-01-01

    The SCanning Imaging Absorption SpectroMeter for Atmospheric CHartographY is an instrument which measures backscattered, reflected, and transmitted light from the earth's atmosphere and surface. SCIAMACHY has eight spectral channels which observe simultaneously the spectral region between 240 and 1700 nm and selected windows between 1940 and 2400 nm. Each spectral channel contains a grating and linear diode array detector. SCIAMACHY observes the atmosphere in nadir, limb, and solar and lunar occultation viewing geometries.

  5. Intrinsic defect oriented visible region absorption in zinc oxide films

    NASA Astrophysics Data System (ADS)

    Rakhesh, V.; Shankar, Balakrishnan

    2018-05-01

    Zinc Oxide films were deposited on the glass substrate using vacuum arc sputtering technology. Films were prepared in oxygen ambience for 10mA and 15 mA deposition current separately. The UV-Visible spectroscopy of the samples showed that both samples possess sharp absorption near 3.5eV which is the characteristic band gap absorption energy of ZnO films. The absorption coefficient were calculated for the samples and the (αℎϑ)2 vs energy plot is drawn. The plot suggested that in addition to the sharp band edge absorption, the sample prepared at 10mA deposition current showed sharp absorption edge near 1.51eV and that at 15 mA showed absorption edge near 1.47eV. This refers to the presence of an intrinsic defect level which is likely to be deep in the band gap.

  6. Optically Unraveling the Edge Chirality-Dependent Band Structure and Plasmon Damping in Graphene Edges.

    PubMed

    Duan, Jiahua; Chen, Runkun; Cheng, Yuan; Yang, Tianzhong; Zhai, Feng; Dai, Qing; Chen, Jianing

    2018-05-01

    The nontrivial topological origin and pseudospinorial character of electron wavefunctions make edge states possess unusual electronic properties. Twenty years ago, the tight-binding model calculation predicted that zigzag termination of 2D sheets of carbon atoms have peculiar edge states, which show potential application in spintronics and modern information technologies. Although scanning probe microscopy is employed to capture this phenomenon, the experimental demonstration of its optical response remains challenging. Here, the propagating graphene plasmon provides an edge-selective polaritonic probe to directly detect and control the electronic edge state at ambient condition. Compared with armchair, the edge-band structure in the bandgap gives rise to additional optical absorption and strongly absorbed rim at zigzag edge. Furthermore, the optical conductivity is reconstructed and the anisotropic plasmon damping in graphene systems is revealed. The reported approach paves the way for detecting edge-specific phenomena in other van der Waals materials and topological insulators. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. The origin of luminescence from di[4-(4-diphenylaminophenyl)phenyl]sulfone (DAPSF), a blue light emitter: an X-ray excited optical luminescence (XEOL) and X-ray absorption near edge structure (XANES) study.

    PubMed

    Zhang, Duo; Zhang, Hui; Zhang, Xiaohong; Sham, Tsun-Kong; Hu, Yongfeng; Sun, Xuhui

    2016-03-07

    The electronic structure and optical properties of di[4-(4-diphenylaminophenyl)phenyl]sulfone (denoted as DAPSF), a highly efficient fluorophor, have been investigated using X-ray excited optical luminescence (XEOL) and X-ray absorption near edge structure (XANES) spectroscopy at excitation energies across the C, N, O K-edges and the sulfur K-edge. The results indicate that the blue luminescence is mainly related to the sulfur functional group.

  8. Model and reconstruction of a K-edge contrast agent distribution with an X-ray photon-counting detector

    PubMed Central

    Meng, Bo; Cong, Wenxiang; Xi, Yan; De Man, Bruno; Yang, Jian; Wang, Ge

    2017-01-01

    Contrast-enhanced computed tomography (CECT) helps enhance the visibility for tumor imaging. When a high-Z contrast agent interacts with X-rays across its K-edge, X-ray photoelectric absorption would experience a sudden increment, resulting in a significant difference of the X-ray transmission intensity between the left and right energy windows of the K-edge. Using photon-counting detectors, the X-ray intensity data in the left and right windows of the K-edge can be measured simultaneously. The differential information of the two kinds of intensity data reflects the contrast-agent concentration distribution. K-edge differences between various matters allow opportunities for the identification of contrast agents in biomedical applications. In this paper, a general radon transform is established to link the contrast-agent concentration to X-ray intensity measurement data. An iterative algorithm is proposed to reconstruct a contrast-agent distribution and tissue attenuation background simultaneously. Comprehensive numerical simulations are performed to demonstrate the merits of the proposed method over the existing K-edge imaging methods. Our results show that the proposed method accurately quantifies a distribution of a contrast agent, optimizing the contrast-to-noise ratio at a high dose efficiency. PMID:28437900

  9. Determination of Scattering and Absorption Coefficients for Plasma-Sprayed Yttria-Stabilized Zirconia Thermal Barrier Coatings at Elevated Temperatures

    NASA Technical Reports Server (NTRS)

    Eldridge, Jeffrey I.; Spuckler, Charles M.; Markham, James R.

    2009-01-01

    The temperature dependence of the scattering and absorption coefficients for a set of freestanding plasma-sprayed 8 wt% yttria-stabilized zirconia (8YSZ) thermal barrier coatings (TBCs) was determined at temperatures up to 1360 C in a wavelength range from 1.2 micrometers up to the 8YSZ absorption edge. The scattering and absorption coefficients were determined by fitting the directional-hemispherical reflectance and transmittance values calculated by a four-flux Kubelka Munk method to the experimentally measured hemispherical-directional reflectance and transmittance values obtained for five 8YSZ thicknesses. The scattering coefficient exhibited a continuous decrease with increasing wavelength and showed no significant temperature dependence. The scattering is primarily attributed to the relatively temperature-insensitive refractive index mismatch between the 8YSZ and its internal voids. The absorption coefficient was very low (less than 1 per centimeter) at wavelengths between 2 micrometers and the absorption edge and showed a definite temperature dependence that consisted of a shift of the absorption edge to shorter wavelengths and an increase in the weak absorption below the absorption edge with increasing temperature. The shift in the absorption edge with temperature is attributed to strongly temperature-dependent multiphonon absorption. While TBC hemispherical transmittance beyond the absorption edge can be predicted by a simple exponential decrease with thickness, below the absorption edge, typical TBC thicknesses are well below the thickness range where a simple exponential decrease in hemispherical transmittance with TBC thickness is expected. [Correction added after online publication August 11, 2009: "edge to a shorter wavelengths" has been updated as edge to shorter wavelengths."

  10. Image Edge Tracking via Ant Colony Optimization

    NASA Astrophysics Data System (ADS)

    Li, Ruowei; Wu, Hongkun; Liu, Shilong; Rahman, M. A.; Liu, Sanchi; Kwok, Ngai Ming

    2018-04-01

    A good edge plot should use continuous thin lines to describe the complete contour of the captured object. However, the detection of weak edges is a challenging task because of the associated low pixel intensities. Ant Colony Optimization (ACO) has been employed by many researchers to address this problem. The algorithm is a meta-heuristic method developed by mimicking the natural behaviour of ants. It uses iterative searches to find the optimal solution that cannot be found via traditional optimization approaches. In this work, ACO is employed to track and repair broken edges obtained via conventional Sobel edge detector to produced a result with more connected edges.

  11. Wavelength calibration of imaging spectrometer using atmospheric absorption features

    NASA Astrophysics Data System (ADS)

    Zhou, Jiankang; Chen, Yuheng; Chen, Xinhua; Ji, Yiqun; Shen, Weimin

    2012-11-01

    Imaging spectrometer is a promising remote sensing instrument widely used in many filed, such as hazard forecasting, environmental monitoring and so on. The reliability of the spectral data is the determination to the scientific communities. The wavelength position at the focal plane of the imaging spectrometer will change as the pressure and temperature vary, or the mechanical vibration. It is difficult for the onboard calibration instrument itself to keep the spectrum reference accuracy and it also occupies weight and the volume of the remote sensing platform. Because the spectral images suffer from the atmospheric effects, the carbon oxide, water vapor, oxygen and solar Fraunhofer line, the onboard wavelength calibration can be processed by the spectral images themselves. In this paper, wavelength calibration is based on the modeled and measured atmospheric absorption spectra. The modeled spectra constructed by the atmospheric radiative transfer code. The spectral angle is used to determine the best spectral similarity between the modeled spectra and measured spectra and estimates the wavelength position. The smile shape can be obtained when the matching process across all columns of the data. The present method is successful applied on the Hyperion data. The value of the wavelength shift is obtained by shape matching of oxygen absorption feature and the characteristics are comparable to that of the prelaunch measurements.

  12. Edge Evaluation Using Local Edge Coherence

    DTIC Science & Technology

    1980-12-01

    response within each region. (The operators discussed below also compute an esti- mate of the direction of brightness change .) In the next step, the edges...worth remarking on is that Abdou and Pratt vary the relative strength of signal to noise by holding the contrast constant and changing the standard...threshold level on the basis of the busyness of the resulting thresholded image.) In applications where edge extraction is an important part of the processing

  13. Optical Absorption in Liquid Semiconductors

    NASA Astrophysics Data System (ADS)

    Bell, Florian Gene

    An infrared absorption cell has been developed which is suitable for high temperature liquids which have absorptions in the range .1-10('3) cm('-1). The cell is constructed by clamping a gasket between two flat optical windows. This unique design allows the use of any optical windows chemically compatible with the liquid. The long -wavelength limit of the measurements is therefore limited only by the choice of the optical windows. The thickness of the cell can easily be set during assembly, and can be varied from 50 (mu)m to .5 cm. Measurements of the optical absorption edge were performed on the liquid alloy Se(,1-x)Tl(,x) for x = 0, .001, .002, .003, .005, .007, and .009, from the melting point up to 475(DEGREES)C. The absorption was found to be exponential in the photon energy over the experimental range from 0.3 eV to 1.2 eV. The absorption increased linearly with concentration according to the empirical relation (alpha)(,T)(h(nu)) = (alpha)(,1) + (alpha)(,2)x, and the absorption (alpha)(,1) was interpreted as the absorption in the absence of T1. (alpha)(,1) also agreed with the measured absorption in 100% Se at corresponding temperatures and energies. The excess absorption defined by (DELTA)(alpha) = (alpha)(,T)(h(nu))-(alpha)(,1) was interpreted as the absorption associated with Tl and was found to be thermally activated with an activation energy E(,t) = 0.5 eV. The exponential edge is explained as absorption on atoms immersed in strong electric fields surrounding ions. The strong fields give rise to an absorption tail similar to the Franz-Keldysh effect. A simple calculation is performed which is based on the Dow-Redfield theory of absorption in an electric field with excitonic effects included. The excess absorption at low photon energies is proportional to the square of the concentration of ions, which are proposed to exist in the liquid according to the relation C(,i) (PROPORTIONAL) x(' 1/2)(.)e('-E)t('/kT), which is the origin of the thermal activation

  14. L-Edge X-ray Absorption Spectroscopic Investigation of {FeNO} 6: Delocalization vs Antiferromagnetic Coupling

    DOE PAGES

    Yan, James J.; Gonzales, Margarita A.; Mascharak, Pradip K.; ...

    2016-12-22

    NO is a classic non-innocent ligand, and iron nitrosyls can have different electronic structure descriptions depending on their spin state and coordination environment. These highly covalent ligands are found in metalloproteins and are also used as models for Fe–O 2 systems. Here, this study utilizes iron L-edge X-ray absorption spectroscopy (XAS), interpreted using a valence bond configuration interaction multiplet model, to directly experimentally probe the electronic structure of the S = 0 {FeNO} 6 compound [Fe(PaPy 3)NO] 2+ (PaPy 3 = N,N-bis(2-pyridylmethyl)amine-N-ethyl-2-pyridine-2-carboxamide) and the S = 0 [Fe(PaPy 3)CO] + reference compound. This method allows separation of the σ-donation andmore » π-acceptor interactions of the ligand through ligand-to-metal and metal-to-ligand charge-transfer mixing pathways. The analysis shows that the {FeNO} 6 electronic structure is best described as Fe III–NO(neutral), with no localized electron in an NO π* orbital or electron hole in an Fe dπ orbital. This delocalization comes from the large energy gap between the Fe–NO π-bonding and antibonding molecular orbitals relative to the exchange interactions between electrons in these orbitals. This study demonstrates the utility of L-edge XAS in experimentally defining highly delocalized electronic structures.« less

  15. Dynamic study of sub-micro sized LiFePO4 cathodes by in-situ tender X-ray absorption near edge structure

    NASA Astrophysics Data System (ADS)

    Wang, Dongniu; Wang, Huixin; Yang, Jinli; Zhou, Jigang; Hu, Yongfeng; Xiao, Qunfeng; Fang, Haitao; Sham, Tsun-Kong

    2016-01-01

    Olivine-type phosphates (LiMPO4, M = Fe, Mn, Co) are promising cathode materials for lithium-ion batteries that are generally accepted to follow first order equilibrium phase transformations. Herein, the phase transformation dynamics of sub-micro sized LiFePO4 particles with limited rate capability at a low current density of 0.14 C was investigated. An in-situ X-ray Absorption Near Edge Structure (XANES) measurement was conducted at the Fe and P K-edge for the dynamic studies upon lithiation and delithiation. Fe K-edge XANES spectra demonstrate that not only lithium-rich intermediate phase LixFePO4 (x = 0.6-0.75), but also lithium-poor intermediate phase LiyFePO4 (y = 0.1-0.25) exist during the charge and discharge, respectively. Furthermore, during charge and discharge, a fluctuation of the FePO4 and LiFePO4 fractions obtained by liner combination fitting around the imaginary phase fractions followed Faraday's law and the equilibrium first-order two-phase transformation versus reaction time is present, respectively. The charging and discharging process has a reversible phase transformation dynamics with symmetric structural evolution routes. P K-edge XANES spectra reveal an enrichment of PF6-1 anions at the surface of the electrode during charging.

  16. Aluminium X-ray absorption Near Edge Structure in model compounds and Earth's surface minerals

    NASA Astrophysics Data System (ADS)

    Ildefonse, P.; Cabaret, D.; Sainctavit, P.; Calas, G.; Flank, A.-M.; Lagarde, P.

    Aluminium K-edge X-ray absorption near edge spectra (XANES) of a suite of silicate and oxides minerals consist of electronic excitations occurring in the edge region, and multiple scattering resonances at higher energies. The main XANES feature for four-fold Al is at around 2 eV lower energy than the main XANES feature for six-fold Al. This provides a useful probe for coordination numbers in clay minerals, gels, glasses or material with unknown Al-coordination number. Six-fold aluminium yields a large variety of XANES features which can be correlated with octahedral point symmetry, number of aluminium sites and distribution of Al-O distances. These three parameters may act together, and the quantitative interpretation of XANES spectra is difficult. For a low point symmetry (1), variations are mainly related to the number of Al sites and distribution of Al-O distances: pyrophyllite, one Al site, is clearly distinguished from kaolinite and gibbsite presenting two Al sites. For a given number of Al-site (1), variations are controlled by changes in point symmetry, the number of XANES features being increased as point symmetry decreases. For a given point symmetry (1) and a given number of Al site (1), variations are related to second nearest neighbours (gibbsite versus kaolinite). The amplitude of the XANES feature at about 1566 eV is a useful probe for the assessment of AlIV/Altotal ratios in 2/1 phyllosilicates. Al-K XANES has been performed on synthetic Al-bearing goethites which cannot be studied by 27Al NMR. At low Al content, Al-K XANES is very different from that of α-AlOOH but at the highest level, XANES spectrum tends to that of diaspore. Al-K XAS is thus a promising tool for the structural study of poorly ordered materials such as clay minerals and natural alumino-silicate gels together with Al-subsituted Fe-oxyhydroxides.

  17. Cell edge detection in JPEG2000 wavelet domain - analysis on sigmoid function edge model.

    PubMed

    Punys, Vytenis; Maknickas, Ramunas

    2011-01-01

    Big virtual microscopy images (80K x 60K pixels and larger) are usually stored using the JPEG2000 image compression scheme. Diagnostic quantification, based on image analysis, might be faster if performed on compressed data (approx. 20 times less the original amount), representing the coefficients of the wavelet transform. The analysis of possible edge detection without reverse wavelet transform is presented in the paper. Two edge detection methods, suitable for JPEG2000 bi-orthogonal wavelets, are proposed. The methods are adjusted according calculated parameters of sigmoid edge model. The results of model analysis indicate more suitable method for given bi-orthogonal wavelet.

  18. Self-Supported Copper Oxide Electrocatalyst for Water Oxidation at Low Overpotential and Confirmation of Its Robustness by Cu K-edge X-ray Absorption Spectroscopy

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Liu, Xiang; Cui, Shengsheng; Sun, Zijun

    Developing efficient water oxidation catalysts made of earth-abundant elements is a demanding challenge that should be met to fulfill the promise of water splitting for clean energy. Herein we report an annealing approach to synthesize binder-free, self-supported heterogeneous copper oxide (CuO) on conductive electrodes for oxygen evolution reaction (OER), producing electrodes with excellent electrocatalytic properties such as high efficiency, low overpotential, and good stability. The catalysts were grown in situ on fluorine-doped tin oxide (FTO) by electrodeposition from a simple Cu(II) salt solution, followed by annealing at a high temperature. Under optimal conditions, the CuO-based OER catalyst shows an onsetmore » potential of <0.58 V (vs Ag/AgCl) in 1.0 M KOH at pH 13.6. From the Tafel plot, the required overpotentials for current densities of 0.1 and 1.0 mA/cm2 are only 360 and 430 mV, respectively. The structure and the presence of a CuO motif in the catalyst have been identified by high-energy X-ray diffraction (HE-XRD), Cu K-edge X-ray absorption (XAS) spectra including X-ray absorption near-edge structure (XANES), and extended X-ray absorption fine structure (EXAFS). To the best of our knowledge, this represents the best catalytic activity for CuO-based OER catalysts to date.« less

  19. High-Throughput Method for Automated Colony and Cell Counting by Digital Image Analysis Based on Edge Detection

    PubMed Central

    Choudhry, Priya

    2016-01-01

    Counting cells and colonies is an integral part of high-throughput screens and quantitative cellular assays. Due to its subjective and time-intensive nature, manual counting has hindered the adoption of cellular assays such as tumor spheroid formation in high-throughput screens. The objective of this study was to develop an automated method for quick and reliable counting of cells and colonies from digital images. For this purpose, I developed an ImageJ macro Cell Colony Edge and a CellProfiler Pipeline Cell Colony Counting, and compared them to other open-source digital methods and manual counts. The ImageJ macro Cell Colony Edge is valuable in counting cells and colonies, and measuring their area, volume, morphology, and intensity. In this study, I demonstrate that Cell Colony Edge is superior to other open-source methods, in speed, accuracy and applicability to diverse cellular assays. It can fulfill the need to automate colony/cell counting in high-throughput screens, colony forming assays, and cellular assays. PMID:26848849

  20. Research on improved edge extraction algorithm of rectangular piece

    NASA Astrophysics Data System (ADS)

    He, Yi-Bin; Zeng, Ya-Jun; Chen, Han-Xin; Xiao, San-Xia; Wang, Yan-Wei; Huang, Si-Yu

    Traditional edge detection operators such as Prewitt operator, LOG operator and Canny operator, etc. cannot meet the requirements of the modern industrial measurement. This paper proposes a kind of image edge detection algorithm based on improved morphological gradient. It can be detect the image using structural elements, which deals with the characteristic information of the image directly. Choosing different shapes and sizes of structural elements to use together, the ideal image edge information can be detected. The experimental result shows that the algorithm can well extract image edge with noise, which is clearer, and has more detailed edges compared with the previous edge detection algorithm.

  1. Extremely asymmetric diffraction as a method of determining magneto-optical constants for X-rays near absorption edges

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Andreeva, M. A., E-mail: Mandreeva1@yandex.ru; Repchenko, Yu. L., E-mail: kent160@mail.ru; Smekhova, A. G.

    2015-06-15

    The spectral dependence of the Bragg peak position under conditions of extremely asymmetric diffraction has been analyzed in the kinematical and dynamical approximations of the diffraction theory. Simulations have been performed for the L{sub 3} absorption edge of yttrium in a single-crystal YFe{sub 2} film; they have shown that the magneto-optical constants (or, equivalently, the dispersion corrections to the atomic scattering factor) for hard X-rays can be determined from this dependence. Comparison with the experimental data obtained for a Nb(4 nm)/YFe{sub 2}(40 nm〈110〉)/Fe(1.5 nm)/Nb(50 nm)/sapphire sample at the European Synchrotron Radiation Facility has been made.

  2. Morphological-transformation-based technique of edge detection and skeletonization of an image using a single spatial light modulator

    NASA Astrophysics Data System (ADS)

    Munshi, Soumika; Datta, A. K.

    2003-03-01

    A technique of optically detecting the edge and skeleton of an image by defining shift operations for morphological transformation is described. A (2 × 2) source array, which acts as the structuring element of morphological operations, casts four angularly shifted optical projections of the input image. The resulting dilated image, when superimposed with the complementary input image, produces the edge image. For skeletonization, the source array casts four partially overlapped output images of the inverted input image, which is negated, and the resultant image is recorded in a CCD camera. This overlapped eroded image is again eroded and then dilated, producing an opened image. The difference between the eroded and opened image is then computed, resulting in a thinner image. This procedure of obtaining a thinned image is iterated until the difference image becomes zero, maintaining the connectivity conditions. The technique has been optically implemented using a single spatial modulator and has the advantage of single-instruction parallel processing of the image. The techniques have been tested both for binary and grey images.

  3. Sensitivity of photon-counting based K-edge imaging in X-ray computed tomography.

    PubMed

    Roessl, Ewald; Brendel, Bernhard; Engel, Klaus-Jürgen; Schlomka, Jens-Peter; Thran, Axel; Proksa, Roland

    2011-09-01

    The feasibility of K-edge imaging using energy-resolved, photon-counting transmission measurements in X-ray computed tomography (CT) has been demonstrated by simulations and experiments. The method is based on probing the discontinuities of the attenuation coefficient of heavy elements above and below the K-edge energy by using energy-sensitive, photon counting X-ray detectors. In this paper, we investigate the dependence of the sensitivity of K-edge imaging on the atomic number Z of the contrast material, on the object diameter D , on the spectral response of the X-ray detector and on the X-ray tube voltage. We assume a photon-counting detector equipped with six adjustable energy thresholds. Physical effects leading to a degradation of the energy resolution of the detector are taken into account using the concept of a spectral response function R(E,U) for which we assume four different models. As a validation of our analytical considerations and in order to investigate the influence of elliptically shaped phantoms, we provide CT simulations of an anthropomorphic Forbild-Abdomen phantom containing a gold-contrast agent. The dependence on the values of the energy thresholds is taken into account by optimizing the achievable signal-to-noise ratios (SNR) with respect to the threshold values. We find that for a given X-ray spectrum and object size the SNR in the heavy element's basis material image peaks for a certain atomic number Z. The dependence of the SNR in the high- Z basis-material image on the object diameter is the natural, exponential decrease with particularly deteriorating effects in the case where the attenuation from the object itself causes a total signal loss below the K-edge. The influence of the energy-response of the detector is very important. We observed that the optimal SNR values obtained with an ideal detector and with a CdTe pixel detector whose response, showing significant tailing, has been determined at a synchrotron differ by factors of

  4. [Accuracy of Modulation Transfer Function for Target Size and Field of View in a Circular Edge Strategy Using the CT Image Measurement Program].

    PubMed

    Fukunaga, Masaaki; Onishi, Hideo; Matsutomo, Norikazu; Yamamoto, Hiroyuki

    2016-06-01

    The purpose of this study was to evaluate the effects of target diameter and display-field of view (D-FOV) in modulation transfer function (MTF) by circular edge strategy using the computed tomography (CT) image measurement program "CTmeasure". We calculated the MTF (MTF(edge)) using the circular edge strategy applied to cylindrical phantom (200 mmφ) that inserted with cylinders have 10, 20, 30, and 40 mm diameters. The phantom images were reconstructed using filtered back projection method varied with D-FOV (240, 320, 400, and 500 mm). The study compared both MTF(edge) and MTF(wire) at MTF50% and MTF(10%) for target diameter and D-FOV, respectively. The MTF(edge) by the different of target diameter indicated in rough compatibility. However, MTF(edge) of D-FOV diameters (320, 400, and 500 mm) decreased in the high frequency range. The circular edge strategy for MTF depended on the D-FOV, however, it was little dependent on target diameter using the CT image measurement program "CTmeasure".

  5. In vivo imaging of scattering and absorption properties of exposed brain using a digital red-green-blue camera

    NASA Astrophysics Data System (ADS)

    Nishidate, Izumi; Yoshida, Keiichiro; Kawauchi, Satoko; Sato, Shunichi; Sato, Manabu

    2014-03-01

    We investigate a method to estimate the spectral images of reduced scattering coefficients and the absorption coefficients of in vivo exposed brain tissues in the range from visible to near-infrared wavelength (500-760 nm) based on diffuse reflectance spectroscopy using a digital RGB camera. In the proposed method, the multi-spectral reflectance images of in vivo exposed brain are reconstructed from the digital red, green blue images using the Wiener estimation algorithm. The Monte Carlo simulation-based multiple regression analysis for the absorbance spectra is then used to specify the absorption and scattering parameters of brain tissue. In this analysis, the concentration of oxygenated hemoglobin and that of deoxygenated hemoglobin are estimated as the absorption parameters whereas the scattering amplitude a and the scattering power b in the expression of μs'=aλ-b as the scattering parameters, respectively. The spectra of absorption and reduced scattering coefficients are reconstructed from the absorption and scattering parameters, and finally, the spectral images of absorption and reduced scattering coefficients are estimated. The estimated images of absorption coefficients were dominated by the spectral characteristics of hemoglobin. The estimated spectral images of reduced scattering coefficients showed a broad scattering spectrum, exhibiting larger magnitude at shorter wavelengths, corresponding to the typical spectrum of brain tissue published in the literature. In vivo experiments with exposed brain of rats during CSD confirmed the possibility of the method to evaluate both hemodynamics and changes in tissue morphology due to electrical depolarization.

  6. Sulfur K-edge extended X-ray absorption fine structure spectroscopy of homoleptic thiolato complexes with Zn(II) and Cd(II).

    PubMed

    Matsunaga, Yuki; Fujisawa, Kiyoshi; Ibi, Naoko; Fujita, Mitsuharu; Ohashi, Tetuya; Amir, Nagina; Miyashita, Yoshitaro; Aika, Ken-Ichi; Izumi, Yasuo; Okamoto, Ken-Ichi

    2006-02-01

    The sulfur K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy is applied to homoleptic thiolato complexes with Zn(II) and Cd(II), (Et(4)N)[Zn(SAd)(3)] (1), (Et(4)N)(2)[{Zn(ScHex)(2)}(2)(mu-ScHex)(2)] (2), (Et(4)N)(2)[{Cd(ScHex)(2)}(2)(mu-ScHex)(2)] (3), (Et(4)N)(2)[{Cd(ScHex)}(4)(mu-ScHex)(6)] (4), [Zn(mu-SAd)(2)](n) (5), and [Cd(mu-SAd)(2)](n) (6) (HSAd=1-adamantanethiol, HScHex=cyclohexanethiol). The EXAFS results are consistent with the X-ray crystal data of 1-4. The structures of 5 and 6, which have not been determined by X-ray crystallography, are proposed to be polynuclear structures on the basis of the sulfur K-edge EXAFS, far-IR spectra, and elemental analysis. Clear evidences of the S...S interactions (between bridging atoms or neighboring sulfur atoms) and the S...C(far) interactions (in which C(far) atom is next to carbon atom directly bonded to sulfur atom) were observed in the EXAFS data for all complexes and thus lead to the reliable determination of the structures of 5 and 6 in combination with conventional zinc K-edge EXAFS analysis for 5. This new methodology, sulfur K-edge EXAFS, could be applied for the structural determination of in vivo metalloproteins as well as inorganic compounds.

  7. Nb K-edge x-ray absorption investigation of the pressure induced amorphization in A-site deficient double perovskite La1/3NbO3.

    PubMed

    Marini, C; Noked, O; Kantor, I; Joseph, B; Mathon, O; Shuker, R; Kennedy, B J; Pascarelli, S; Sterer, E

    2016-02-03

    Nb K-edge x-ray absorption spectroscopy is utilized to investigate the changes in the local structure of the A-site deficient double perovskite La1/3NbO3 which undergoes a pressure induced irreversible amorphization. EXAFS results show that with increasing pressure up to 7.5 GPa, the average Nb-O bond distance decreases in agreement with the expected compression and tilting of the NbO6 octahedra. On the contrary, above 7.5 GPa, the average Nb-O bond distance show a tendency to increase. Significant changes in the Nb K-edge XANES spectrum with evident low energy shift of the pre-peak and the absorption edge is found to happen in La1/3NbO3 above 6.3 GPa. These changes evidence a gradual reduction of the Nb cations from Nb(5+) towards Nb(4+) above 6.3 GPa. Such a valence change accompanied by the elongation of the average Nb-O bond distances in the octahedra, introduces repulsion forces between non-bonding adjacent oxygen anions in the unoccupied A-sites. Above a critical pressure, the Nb reduction mechanism can no longer be sustained by the changing local structure and amorphization occurs, apparently due to the build-up of local strain. EXAFS and XANES results indicate two distinct pressure regimes having different local and electronic response in the La1/3NbO3 system before the occurence of the pressure induced amorphization at  ∼14.5 GPa.

  8. Quantum Image Processing and Its Application to Edge Detection: Theory and Experiment

    NASA Astrophysics Data System (ADS)

    Yao, Xi-Wei; Wang, Hengyan; Liao, Zeyang; Chen, Ming-Cheng; Pan, Jian; Li, Jun; Zhang, Kechao; Lin, Xingcheng; Wang, Zhehui; Luo, Zhihuang; Zheng, Wenqiang; Li, Jianzhong; Zhao, Meisheng; Peng, Xinhua; Suter, Dieter

    2017-07-01

    Processing of digital images is continuously gaining in volume and relevance, with concomitant demands on data storage, transmission, and processing power. Encoding the image information in quantum-mechanical systems instead of classical ones and replacing classical with quantum information processing may alleviate some of these challenges. By encoding and processing the image information in quantum-mechanical systems, we here demonstrate the framework of quantum image processing, where a pure quantum state encodes the image information: we encode the pixel values in the probability amplitudes and the pixel positions in the computational basis states. Our quantum image representation reduces the required number of qubits compared to existing implementations, and we present image processing algorithms that provide exponential speed-up over their classical counterparts. For the commonly used task of detecting the edge of an image, we propose and implement a quantum algorithm that completes the task with only one single-qubit operation, independent of the size of the image. This demonstrates the potential of quantum image processing for highly efficient image and video processing in the big data era.

  9. Solving local structure around dopants in metal nanoparticles with ab initio modeling of X-ray absorption near edge structure

    DOE PAGES

    Timoshenko, J.; Shivhare, A.; Scott, R. W.; ...

    2016-06-30

    We adopted ab-initio X-ray Absorption Near Edge Structure (XANES) modelling for structural refinement of local environments around metal impurities in a large variety of materials. Our method enables both direct modelling, where the candidate structures are known, and the inverse modelling, where the unknown structural motifs are deciphered from the experimental spectra. We present also estimates of systematic errors, and their influence on the stability and accuracy of the obtained results. We illustrate our approach by following the evolution of local environment of palladium atoms in palladium-doped gold thiolate clusters upon chemical and thermal treatments.

  10. Pulsed laser linescanner for a backscatter absorption gas imaging system

    DOEpatents

    Kulp, Thomas J.; Reichardt, Thomas A.; Schmitt, Randal L.; Bambha, Ray P.

    2004-02-10

    An active (laser-illuminated) imaging system is described that is suitable for use in backscatter absorption gas imaging (BAGI). A BAGI imager operates by imaging a scene as it is illuminated with radiation that is absorbed by the gas to be detected. Gases become "visible" in the image when they attenuate the illumination creating a shadow in the image. This disclosure describes a BAGI imager that operates in a linescanned manner using a high repetition rate pulsed laser as its illumination source. The format of this system allows differential imaging, in which the scene is illuminated with light at least 2 wavelengths--one or more absorbed by the gas and one or more not absorbed. The system is designed to accomplish imaging in a manner that is insensitive to motion of the camera, so that it can be held in the hand of an operator or operated from a moving vehicle.

  11. A threshold selection method based on edge preserving

    NASA Astrophysics Data System (ADS)

    Lou, Liantang; Dan, Wei; Chen, Jiaqi

    2015-12-01

    A method of automatic threshold selection for image segmentation is presented. An optimal threshold is selected in order to preserve edge of image perfectly in image segmentation. The shortcoming of Otsu's method based on gray-level histograms is analyzed. The edge energy function of bivariate continuous function is expressed as the line integral while the edge energy function of image is simulated by discretizing the integral. An optimal threshold method by maximizing the edge energy function is given. Several experimental results are also presented to compare with the Otsu's method.

  12. Transition-edge sensor imaging arrays for astrophysics applications

    NASA Astrophysics Data System (ADS)

    Burney, Jennifer Anne

    Many interesting objects in our universe currently elude observation in the optical band: they are too faint or they vary rapidly and thus any structure in their radiation is lost over the period of an exposure. Conventional photon detectors cannot simultaneously provide energy resolution and time-stamping of individual photons at fast rates. Superconducting detectors have recently made the possibility of simultaneous photon counting, imaging, and energy resolution a reality. Our research group has pioneered the use of one such detector, the Transition-Edge Sensor (TES). TES physics is simple and elegant. A thin superconducting film, biased at its critical temperature, can act as a particle detector: an incident particle deposits energy and drives the film into its superconducting-normal transition. By inductively coupling the detector to a SQUID amplifier circuit, this resistance change can be read out as a current pulse, and its energy deduced by integrating over the pulse. TESs can be used to accurately time-stamp (to 0.1 [mu]s) and energy-resolve (0.15 eV at 1.6 eV) near-IR/visible/near-UV photons at rates of 30~kHz. The first astronomical observations using fiber-coupled detectors were made at the Stanford Student Observatory 0.6~m telescope in 1999. Further observations of the Crab Pulsar from the 107" telescope at the University of Texas McDonald Observatory showed rapid phase variations over the near-IR/visible/near-UV band. These preliminary observations provided a glimpse into a new realm of observations of pulsars, binary systems, and accreting black holes promised by TES arrays. This thesis describes the development, characterization, and preliminary use of the first camera system based on Transition-Edge Sensors. While single-device operation is relatively well-understood, the operation of a full imaging array poses significant challenges. This thesis addresses all aspects related to the creation and characterization of this cryogenic imaging

  13. Solid state image sensing arrays

    NASA Technical Reports Server (NTRS)

    Sadasiv, G.

    1972-01-01

    The fabrication of a photodiode transistor image sensor array in silicon, and tests on individual elements of the array are described along with design for a scanning system for an image sensor array. The spectral response of p-n junctions was used as a technique for studying the optical-absorption edge in silicon. Heterojunction structures of Sb2S3- Si were fabricated and a system for measuring C-V curves on MOS structures was built.

  14. X-ray K-edge absorption spectra of Fe minerals and model compounds: II. EXAFS

    NASA Astrophysics Data System (ADS)

    Waychunas, Glenn A.; Brown, Gordon E.; Apted, Michael J.

    1986-01-01

    K-edge extended X-ray absorption fine structure (EXAFS) spectra of Fe in varying environments in a suite of well-characterized silicate and oxide minerals were collected using synchrotron radiation and analyzed using single scattering approximation theory to yield nearest neighbor Fe-O distances and coordination numbers. The partial inverse character of synthetic hercynite spinal was verified in this way. Comparison of the results from all samples with structural data from X-ray diffraction crystal structure refinements indicates that EXAFS-derived first neighbor distances are generally accurate to ±0.02 Å using only theoretically generated phase information, and may be improved over this if similar model compounds are used to determine EXAFS phase functions. Coordination numbers are accurate to ±20 percent and can be similarly improved using model compound EXAFS amplitude information. However, in particular cases the EXAFS-derived distances may be shortened, and the coordination number reduced, by the effects of static and thermal disorder or by partial overlap of the longer Fe-O first neighbor distances with second neighbor distances in the EXAFS structure function. In the former case the total information available in the EXAFS is limited by the disorder, while in the latter case more accurate results can in principle be obtained by multiple neighbor EXAFS analysis. The EXAFS and XANES spectra of Fe in Nain, Labrador osumulite and Lakeview, Oregon plagioclase are also analyzed as an example of the application of X-ray absorption spectroscopy to metal ion site occupation determination in minerals.

  15. Phase contrast imaging of buccal mucosa tissues-Feasibility study

    NASA Astrophysics Data System (ADS)

    Fatima, A.; Tripathi, S.; Shripathi, T.; Kulkarni, V. K.; Banda, N. R.; Agrawal, A. K.; Sarkar, P. S.; Kashyap, Y.; Sinha, A.

    2015-06-01

    Phase Contrast Imaging (PCI) technique has been used to interpret physical parameters obtained from the image taken on the normal buccal mucosa tissue extracted from cheek of a patient. The advantages of this method over the conventional imaging techniques are discussed. PCI technique uses the X-ray phase shift at the edges differentiated by very minute density differences and the edge enhanced high contrast images reveal details of soft tissues. The contrast in the images produced is related to changes in the X-ray refractive index of the tissues resulting in higher clarity compared with conventional absorption based X-ray imaging. The results show that this type of imaging has better ability to visualize microstructures of biological soft tissues with good contrast, which can lead to the diagnosis of lesions at an early stage of the diseases.

  16. Forty-five degree backscattering-mode nonlinear absorption imaging in turbid media.

    PubMed

    Cui, Liping; Knox, Wayne H

    2010-01-01

    Two-color nonlinear absorption imaging has been previously demonstrated with endogenous contrast of hemoglobin and melanin in turbid media using transmission-mode detection and a dual-laser technology approach. For clinical applications, it would be generally preferable to use backscattering mode detection and a simpler single-laser technology. We demonstrate that imaging in backscattering mode in turbid media using nonlinear absorption can be obtained with as little as 1-mW average power per beam with a single laser source. Images have been achieved with a detector receiving backscattered light at a 45-deg angle relative to the incoming beams' direction. We obtain images of capillary tube phantoms with resolution as high as 20 microm and penetration depth up to 0.9 mm for a 300-microm tube at SNR approximately 1 in calibrated scattering solutions. Simulation results of the backscattering and detection process using nonimaging optics are demonstrated. A Monte Carlo-based method shows that the nonlinear signal drops exponentially as the depth increases, which agrees well with our experimental results. Simulation also shows that with our current detection method, only 2% of the signal is typically collected with a 5-mm-radius detector.

  17. EDGES result versus CMB and low-redshift constraints on ionization histories

    NASA Astrophysics Data System (ADS)

    Witte, Samuel; Villanueva-Domingo, Pablo; Gariazzo, Stefano; Mena, Olga; Palomares-Ruiz, Sergio

    2018-05-01

    We examine the results from the Experiment to Detect the Global Epoch of Reionization Signature (EDGES), which has recently claimed the detection of a strong absorption in the 21 cm hyperfine transition line of neutral hydrogen, at redshifts demarcating the early stages of star formation. More concretely, we study the compatibility of the shape of the EDGES absorption profile, centered at a redshift of z ˜17.2 , with measurements of the reionization optical depth, the Gunn-Peterson optical depth, and Lyman-α emission from star-forming galaxies, for a variety of possible reionization models within the standard Λ CDM framework (that is, a Universe with a cosmological constant Λ and cold dark matter CDM). When, conservatively, we only try to accommodate the location of the absorption dip, we identify a region in the parameter space of the astrophysical parameters that successfully explains all of the aforementioned observations. However, one of the most abnormal features of the EDGES measurement is the absorption amplitude, which is roughly a factor of 2 larger than the maximum allowed value in the Λ CDM framework. We point out that the simple considered astrophysical models that produce the largest absorption amplitudes are unable to explain the depth of the dip and of reproducing the observed shape of the absorption profile.

  18. [Effect of Long-Term Fertilization on Organic Nitrogen Functional Groups in Black Soil as Revealed by Synchrotron-Based X-Ray Absorption Near-Edge Structure Spectroscopy].

    PubMed

    Li, Hui; Gao, Qiang; Wang, Shuai; Zhu, Ping; Zhang, Jin-jing; Zhao, Yi-dong

    2015-07-01

    Nitrogen (N) is a common limiting nutrient in crop production. The N content of soil has been used as an important soil fertility index. Organic N is the major form of N in soil. In most agricultural surface soils, more than 90% of total N occurs in organic forms. Therefore, understanding the compositional characteristics of soil organic N functional groups can provide the scientific basis for formulating the reasonable farmland management strategies. Synchrotron radiation soft X-ray absorption near-edge structure (N K-edge XANES) spectroscopy is the most powerful tool to characterize in situ organic N functional groups compositions in soil. However, to our most knowledge, no studies have been conducted to examine the organic N functional groups compositions of soil using N K-edge XANES spectroscopy under long-term fertilization practices. Based on a long-term field experiment (started in 1990) in a black soil (Gongzhuling, Northeast China), we investigated the differences in organic N functional groups compositions in bulk soil and clay-size soil fraction among fertilization patterns using synchrotron-based N K- edge XANES spectroscopy. Composite soil samples (0-20 cm) were collected in 2008. The present study included six treatments: farmland fallow (FALL), no-fertilization control (CK), chemical nitrogen, phosphorus, and potassium fertilization (NPK), NPK in combination with organic manure (NPKM), 1.5 times of NPKM (1.5 NPKM), and NPK in combination with maize straw (NPKS). The results showed that N K-edge XANES spectra of all the treatments under study exhibited characteristic absorption peaks in the ranges of 401.2-401.6 and 402.7-403.1 eV, which were assigned as amides/amine-N and pyrrole-N, respectively. These characteristic absorption peaks were more obvious in clay-size soil fraction than in bulk soil. The results obtained from the semi-quantitative analysis of N K-edge XANES spectra indicated that the relative proportion of amides/amine-N was the highest

  19. Assessment of transmitral flow after mitral valve edge-to-edge repair using High-speed particle image velocimetry

    NASA Astrophysics Data System (ADS)

    Jeyhani, Morteza; Shahriari, Shahrokh; Labrosse, Michel; Kadem, Lyes

    2013-11-01

    Approximately 500,000 people in North America suffer from mitral valve regurgitation (MR). MR is a disorder of the heart in which the mitral valve (MV) leaflets do not close securely during systole. Edge-to-edge repair (EtER) technique can be used to surgically treat MR. This technique produces a double-orifice configuration for the MV. Under these un-physiological conditions, flow downstream of the MV forms a double jet structure that may disturb the intraventricular hemodynamics. Abnormal flow patterns following EtER are mainly characterized by high-shear stress and stagnation zones in the left ventricle (LV), which increase the potential of blood component damage. In this study, a custom-made prosthetic bicuspid MV was used to analyze the LV flow patterns after EtER by means of digital particle image velocimetry (PIV). Although the repair of a MV using EtER technique is an effective approach, this study confirms that EtER leads to changes in the LV flow field, including the generation of a double mitral jet flow and high shear stress regions.

  20. Automatic Assessment and Reduction of Noise using Edge Pattern Analysis in Non-Linear Image Enhancement

    NASA Technical Reports Server (NTRS)

    Jobson, Daniel J.; Rahman, Zia-Ur; Woodell, Glenn A.; Hines, Glenn D.

    2004-01-01

    Noise is the primary visibility limit in the process of non-linear image enhancement, and is no longer a statistically stable additive noise in the post-enhancement image. Therefore novel approaches are needed to both assess and reduce spatially variable noise at this stage in overall image processing. Here we will examine the use of edge pattern analysis both for automatic assessment of spatially variable noise and as a foundation for new noise reduction methods.

  1. Contrast-enhanced dual-energy subtraction imaging using electronic spectrum-splitting and multi-prism x-ray lenses

    NASA Astrophysics Data System (ADS)

    Fredenberg, Erik; Cederström, Björn; Lundqvist, Mats; Ribbing, Carolina; Åslund, Magnus; Diekmann, Felix; Nishikawa, Robert; Danielsson, Mats

    2008-03-01

    Dual-energy subtraction imaging (DES) is a method to improve the detectability of contrast agents over a lumpy background. Two images, acquired at x-ray energies above and below an absorption edge of the agent material, are logarithmically subtracted, resulting in suppression of the signal from the tissue background and a relative enhancement of the signal from the agent. Although promising, DES is still not widely used in clinical practice. One reason may be the need for two distinctly separated x-ray spectra that are still close to the absorption edge, realized through dual exposures which may introduce motion unsharpness. In this study, electronic spectrum-splitting with a silicon-strip detector is theoretically and experimentally investigated for a mammography model with iodinated contrast agent. Comparisons are made to absorption imaging and a near-ideal detector using a signal-to-noise ratio that includes both statistical and structural noise. Similar to previous studies, heavy absorption filtration was needed to narrow the spectra at the expense of a large reduction in x-ray flux. Therefore, potential improvements using a chromatic multi-prism x-ray lens (MPL) for filtering were evaluated theoretically. The MPL offers a narrow tunable spectrum, and we show that the image quality can be improved compared to conventional filtering methods.

  2. Edge-augmented Fourier partial sums with applications to Magnetic Resonance Imaging (MRI)

    NASA Astrophysics Data System (ADS)

    Larriva-Latt, Jade; Morrison, Angela; Radgowski, Alison; Tobin, Joseph; Iwen, Mark; Viswanathan, Aditya

    2017-08-01

    Certain applications such as Magnetic Resonance Imaging (MRI) require the reconstruction of functions from Fourier spectral data. When the underlying functions are piecewise-smooth, standard Fourier approximation methods suffer from the Gibbs phenomenon - with associated oscillatory artifacts in the vicinity of edges and an overall reduced order of convergence in the approximation. This paper proposes an edge-augmented Fourier reconstruction procedure which uses only the first few Fourier coefficients of an underlying piecewise-smooth function to accurately estimate jump information and then incorporate it into a Fourier partial sum approximation. We provide both theoretical and empirical results showing the improved accuracy of the proposed method, as well as comparisons demonstrating superior performance over existing state-of-the-art sparse optimization-based methods.

  3. Sub-surface defects detection of by using active thermography and advanced image edge detection

    NASA Astrophysics Data System (ADS)

    Tse, Peter W.; Wang, Gaochao

    2017-05-01

    Active or pulsed thermography is a popular non-destructive testing (NDT) tool for inspecting the integrity and anomaly of industrial equipment. One of the recent research trends in using active thermography is to automate the process in detecting hidden defects. As of today, human effort has still been using to adjust the temperature intensity of the thermo camera in order to visually observe the difference in cooling rates caused by a normal target as compared to that by a sub-surface crack exists inside the target. To avoid the tedious human-visual inspection and minimize human induced error, this paper reports the design of an automatic method that is capable of detecting subsurface defects. The method used the technique of active thermography, edge detection in machine vision and smart algorithm. An infrared thermo-camera was used to capture a series of temporal pictures after slightly heating up the inspected target by flash lamps. Then the Canny edge detector was employed to automatically extract the defect related images from the captured pictures. The captured temporal pictures were preprocessed by a packet of Canny edge detector and then a smart algorithm was used to reconstruct the whole sequences of image signals. During the processes, noise and irrelevant backgrounds exist in the pictures were removed. Consequently, the contrast of the edges of defective areas had been highlighted. The designed automatic method was verified by real pipe specimens that contains sub-surface cracks. After applying such smart method, the edges of cracks can be revealed visually without the need of using manual adjustment on the setting of thermo-camera. With the help of this automatic method, the tedious process in manually adjusting the colour contract and the pixel intensity in order to reveal defects can be avoided.

  4. Sulfur K-edge X-ray absorption spectroscopy and time-dependent density functional theory of arsenic dithiocarbamates.

    PubMed

    Donahue, Courtney M; Pacheco, Juan S Lezama; Keith, Jason M; Daly, Scott R

    2014-06-28

    S K-edge X-ray absorption spectroscopy (XAS) and time-dependent density functional theory (TDDFT) calculations were performed on a series of As[S2CNR2]3 complexes, where R2 = Et2, (CH2)5 and Ph2, to determine how dithiocarbamate substituents attached to N affect As[S2CNR2]3 electronic structure. Complimentary [PPh4][S2CNR2] salts were also studied to compare dithiocarbamate bonding in the absence of As. The XAS results indicate that changing the orientation of the alkyl substituents from trans to cis (R2 = Et2vs. (CH2)5) yields subtle variations whereas differences associated with a change from alkyl to aryl are much more pronounced. For example, despite the differences in As 4p mixing, the first features in the S K-edge XAS spectra of [PPh4][S2CNPh2] and As[S2CNPh2]3 were both shifted by 0.3 eV compared to their alkyl-substituted derivatives. DFT calculations revealed that the unique shift observed for [PPh4][S2CNPh2] is due to phenyl-induced splitting of the π* orbitals delocalized over N, C and S. A similar phenomenon accounts for the shift observed for As[S2CNPh2]3, but the presence of two unique S environments (As-S and As···S) prevented reliable analysis of As-S covalency from the XAS data. In the absence of experimental values, DFT calculations revealed a decrease in As-S orbital mixing in As[S2CNPh2]3 that stems from a redistribution of electron density to S atoms participating in weaker As···S interactions. Simulated spectra obtained from TDDFT calculations reproduce the experimental differences in the S K-edge XAS data, which suggests that the theory is accurately modeling the experimental differences in As-S orbital mixing. The results highlight how S K-edge XAS and DFT can be used cooperatively to understand the electronic structure of low symmetry coordination complexes containing S atoms in different chemical environments.

  5. Analyser-based mammography using single-image reconstruction.

    PubMed

    Briedis, Dahliyani; Siu, Karen K W; Paganin, David M; Pavlov, Konstantin M; Lewis, Rob A

    2005-08-07

    We implement an algorithm that is able to decode a single analyser-based x-ray phase-contrast image of a sample, converting it into an equivalent conventional absorption-contrast radiograph. The algorithm assumes the projection approximation for x-ray propagation in a single-material object embedded in a substrate of approximately uniform thickness. Unlike the phase-contrast images, which have both directional bias and a bias towards edges present in the sample, the reconstructed images are directly interpretable in terms of the projected absorption coefficient of the sample. The technique was applied to a Leeds TOR[MAM] phantom, which is designed to test mammogram quality by the inclusion of simulated microcalcifications, filaments and circular discs. This phantom was imaged at varying doses using three modalities: analyser-based synchrotron phase-contrast images converted to equivalent absorption radiographs using our algorithm, slot-scanned synchrotron imaging and imaging using a conventional mammography unit. Features in the resulting images were then assigned a quality score by volunteers. The single-image reconstruction method achieved higher scores at equivalent and lower doses than the conventional mammography images, but no improvement of visualization of the simulated microcalcifications, and some degradation in image quality at reduced doses for filament features.

  6. Lunar-edge based on-orbit modulation transfer function (MTF) measurement

    NASA Astrophysics Data System (ADS)

    Cheng, Ying; Yi, Hongwei; Liu, Xinlong

    2017-10-01

    Modulation transfer function (MTF) is an important parameter for image quality evaluation of on-orbit optical image systems. Various methods have been proposed to determine the MTF of an imaging system which are based on images containing point, pulse and edge features. In this paper, the edge of the moon can be used as a high contrast target to measure on-orbit MTF of image systems based on knife-edge methods. The proposed method is an extension of the ISO 12233 Slanted-edge Spatial Frequency Response test, except that the shape of the edge is a circular arc instead of a straight line. In order to get more accurate edge locations and then obtain a more authentic edge spread function (ESF), we choose circular fitting method based on least square to fit lunar edge in sub-pixel edge detection process. At last, simulation results show that the MTF value at Nyquist frequency calculated using our lunar edge method is reliable and accurate with error less than 2% comparing with theoretical MTF value.

  7. A novel cloning template designing method by using an artificial bee colony algorithm for edge detection of CNN based imaging sensors.

    PubMed

    Parmaksızoğlu, Selami; Alçı, Mustafa

    2011-01-01

    Cellular Neural Networks (CNNs) have been widely used recently in applications such as edge detection, noise reduction and object detection, which are among the main computer imaging processes. They can also be realized as hardware based imaging sensors. The fact that hardware CNN models produce robust and effective results has attracted the attention of researchers using these structures within image sensors. Realization of desired CNN behavior such as edge detection can be achieved by correctly setting a cloning template without changing the structure of the CNN. To achieve different behaviors effectively, designing a cloning template is one of the most important research topics in this field. In this study, the edge detecting process that is used as a preliminary process for segmentation, identification and coding applications is conducted by using CNN structures. In order to design the cloning template of goal-oriented CNN architecture, an Artificial Bee Colony (ABC) algorithm which is inspired from the foraging behavior of honeybees is used and the performance analysis of ABC for this application is examined with multiple runs. The CNN template generated by the ABC algorithm is tested by using artificial and real test images. The results are subjectively and quantitatively compared with well-known classical edge detection methods, and other CNN based edge detector cloning templates available in the imaging literature. The results show that the proposed method is more successful than other methods.

  8. A Novel Cloning Template Designing Method by Using an Artificial Bee Colony Algorithm for Edge Detection of CNN Based Imaging Sensors

    PubMed Central

    Parmaksızoğlu, Selami; Alçı, Mustafa

    2011-01-01

    Cellular Neural Networks (CNNs) have been widely used recently in applications such as edge detection, noise reduction and object detection, which are among the main computer imaging processes. They can also be realized as hardware based imaging sensors. The fact that hardware CNN models produce robust and effective results has attracted the attention of researchers using these structures within image sensors. Realization of desired CNN behavior such as edge detection can be achieved by correctly setting a cloning template without changing the structure of the CNN. To achieve different behaviors effectively, designing a cloning template is one of the most important research topics in this field. In this study, the edge detecting process that is used as a preliminary process for segmentation, identification and coding applications is conducted by using CNN structures. In order to design the cloning template of goal-oriented CNN architecture, an Artificial Bee Colony (ABC) algorithm which is inspired from the foraging behavior of honeybees is used and the performance analysis of ABC for this application is examined with multiple runs. The CNN template generated by the ABC algorithm is tested by using artificial and real test images. The results are subjectively and quantitatively compared with well-known classical edge detection methods, and other CNN based edge detector cloning templates available in the imaging literature. The results show that the proposed method is more successful than other methods. PMID:22163903

  9. Microwave Imaging Reflectometry for the study of Edge Harmonic Oscillations on DIII-D [Microwave Imaging Reflectometry (MIR) for the study of Edge Harmonic Oscillations (EHOs) on DIII-D

    DOE PAGES

    Ren, X.; Chen, M.; Chen, X.; ...

    2015-10-23

    Quiescent H-mode (QH) is an ELM free mode of operation in which edge-localized harmonic oscillations (EHOs) are believed to enhance particle transport, thereby stabilizing ELMs and preventing damage to the divertor and plasma facing components. Microwave Imaging Reflectometer (MIR) enabling direct comparison between the measured and simulated 2D images of density fluctuations near the edge can determine the 2D structure of density oscillation which can help to explain the physics behind EHO modes. MIR data sometimes indicates a counter-propagation between higher (n>1) and dominant (n=1) harmonics of coherent EHOs in the steep gradient regions of the pedestal. To preclude diagnosticmore » artifacts, we have performed forward modeling that includes possible optical misalignments to show that offsets between transmitting and receiving antennas do not account for this feature. We have also simulated the non-uniform rotation of the EHO structure, which induces multiple harmonics that are properly characterized in the synthetic diagnostic. Excluding these possible explanations for the data, the counter-propagation observed in MIR data, which is not corroborated by external Mirnov coil array measurements, may be due to subtleties of the eigenmode structure, such as an inversion radius consistent with a magnetic island. Similar effects are observed in analysis of internal ECE-Imaging and BES data. Furthermore, the identification of a non-ideal structure motivates further exploration of nonlinear models of this instability.« less

  10. SU-C-207-06: In Vivo Quantification of Gold Nanoparticles Using K-Edge Imaging Via Spectrum Shaping by Gold Filter

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Chen, H; Cormack, R; Bhagwat, M

    Purpose: Gold nanoparticles (AuNP) are multifunctional platforms ideal for drug delivery, targeted imaging and radiosensitization. We have investigated quantitative imaging of AuNPs using on board imager (OBI) cone beam computed tomography (CBCT). To this end, we also present, for the first time, a novel method for k-edge imaging of AuNP by filter-based spectral shaping. Methods: We used a digital 25 cm diameter water phantom, embedded with 3 cm spheres filled with AuNPs of different concentrations (0 mg/ml – 16 mg/ml). A poly-energetic X-ray spectrum of 140 kVp from a conventional X-ray tube is shaped by balanced K-edge filters to createmore » an excess of photons right above the K-edge of gold at 80.7 keV. The filters consist of gold, tin, copper and aluminum foils. The phantom with appropriately assigned attenuation coefficients is forward projected onto a detector for each energy bin and then integrated. FKD reconstruction is performed on the integrated projections. Scatter, detector efficiency and noise are included. Results: We found that subtracting the results of two filter sets (Filter A:127 µm gold foil with 254 µm tin, 330 µm copper and 1 mm aluminum, and Filter B: 635 µm tin with 264 µm copper and 1 mm aluminum), provides substantial image contrast. The resulting filtered spectra match well below 80.7 keV, while maintaining sufficient X-ray quanta just above that. Voxel intensities of AuNP containing spheres increase linearly with AuNP concentration. K-edge imaging provides 18% more sensitivity than the tin filter alone, and 38% more sensitivity than the gold filter alone. Conclusion: We have shown that it is feasible to quantitatively detect AuNP distributions in a patient-sized phantom using clinical CBCT and K-edge spectral shaping.« less

  11. Few-photon color imaging using energy-dispersive superconducting transition-edge sensor spectrometry

    NASA Astrophysics Data System (ADS)

    Niwa, Kazuki; Numata, Takayuki; Hattori, Kaori; Fukuda, Daiji

    2017-04-01

    Highly sensitive spectral imaging is increasingly being demanded in bioanalysis research and industry to obtain the maximum information possible from molecules of different colors. We introduce an application of the superconducting transition-edge sensor (TES) technique to highly sensitive spectral imaging. A TES is an energy-dispersive photodetector that can distinguish the wavelength of each incident photon. Its effective spectral range is from the visible to the infrared (IR), up to 2800 nm, which is beyond the capabilities of other photodetectors. TES was employed in this study in a fiber-coupled optical scanning microscopy system, and a test sample of a three-color ink pattern was observed. A red-green-blue (RGB) image and a near-IR image were successfully obtained in the few-incident-photon regime, whereas only a black and white image could be obtained using a photomultiplier tube. Spectral data were also obtained from a selected focal area out of the entire image. The results of this study show that TES is feasible for use as an energy-dispersive photon-counting detector in spectral imaging applications.

  12. Few-photon color imaging using energy-dispersive superconducting transition-edge sensor spectrometry.

    PubMed

    Niwa, Kazuki; Numata, Takayuki; Hattori, Kaori; Fukuda, Daiji

    2017-04-04

    Highly sensitive spectral imaging is increasingly being demanded in bioanalysis research and industry to obtain the maximum information possible from molecules of different colors. We introduce an application of the superconducting transition-edge sensor (TES) technique to highly sensitive spectral imaging. A TES is an energy-dispersive photodetector that can distinguish the wavelength of each incident photon. Its effective spectral range is from the visible to the infrared (IR), up to 2800 nm, which is beyond the capabilities of other photodetectors. TES was employed in this study in a fiber-coupled optical scanning microscopy system, and a test sample of a three-color ink pattern was observed. A red-green-blue (RGB) image and a near-IR image were successfully obtained in the few-incident-photon regime, whereas only a black and white image could be obtained using a photomultiplier tube. Spectral data were also obtained from a selected focal area out of the entire image. The results of this study show that TES is feasible for use as an energy-dispersive photon-counting detector in spectral imaging applications.

  13. Molecular imaging analysis of intestinal insulin absorption boosted by cell-penetrating peptides by using positron emission tomography.

    PubMed

    Kamei, Noriyasu; Morishita, Mariko; Kanayama, Yousuke; Hasegawa, Koki; Nishimura, Mie; Hayashinaka, Emi; Wada, Yasuhiro; Watanabe, Yasuyoshi; Takayama, Kozo

    2010-08-17

    Molecular imaging technique by use of positron emission tomography (PET) is a noninvasive tool that allows one to quantitatively analyze the function of endogenous molecules and the pharmacokinetics of therapeutic agents in vivo. This technique is expected to be useful for evaluating the effectiveness of diverse drug delivery systems. We demonstrated previously that intestinal insulin absorption is increased significantly by coadministration of cell-penetrating peptides (CPPs), which are taken up effectively by several cells. However, the distribution behavior of insulin whose absorption is increased by CPPs is not clear. We used PET imaging and quantitatively analyzed the intestinal absorption and subsequent distribution of insulin and the effect of CPPs on its absorption and distribution. An unlabeled insulin solution containing tracer insulin, (68)Ga-DOTA-insulin, was administered with or without CPPs into a rat ileal closed loop. PET imaging showed that the CPPs, particularly D-R8 and L-penetratin, significantly increased the (68)Ga-DOTA-insulin level in the liver, kidney, and circulation. After absorption from the intestine, the (68)Ga-DOTA-insulin passed rapidly through the liver and accumulated in the kidney. The increase in the hepatic and renal distribution of (68)Ga-DOTA-insulin by each CPP coadministration was similar manner as that in intestinal absorption, suggesting that the increased accumulation of insulin in the liver and kidney induced by coadministration of CPPs was associated with the increased intestinal absorption of insulin. This is the first study to show that PET imaging enables one to quantitatively analyze the distribution behavior of intestinally absorbed insulin in several organs. This imaging methodology is likely to be useful for developing effective drug delivery systems targeted to specific organs. Copyright 2010 Elsevier B.V. All rights reserved.

  14. A novel edge based embedding in medical images based on unique key generated using sudoku puzzle design.

    PubMed

    Santhi, B; Dheeptha, B

    2016-01-01

    The field of telemedicine has gained immense momentum, owing to the need for transmitting patients' information securely. This paper puts forth a unique method for embedding data in medical images. It is based on edge based embedding and XOR coding. The algorithm proposes a novel key generation technique by utilizing the design of a sudoku puzzle to enhance the security of the transmitted message. The edge blocks of the cover image alone, are utilized to embed the payloads. The least significant bit of the pixel values are changed by XOR coding depending on the data to be embedded and the key generated. Hence the distortion in the stego image is minimized and the information is retrieved accurately. Data is embedded in the RGB planes of the cover image, thus increasing its embedding capacity. Several measures including peak signal noise ratio (PSNR), mean square error (MSE), universal image quality index (UIQI) and correlation coefficient (R) are the image quality measures that have been used to analyze the quality of the stego image. It is evident from the results that the proposed technique outperforms the former methodologies.

  15. Effects of strain relaxation in Pr 0.67Sr 0.33MnO 3 films probed by polarization dependent X-ray absorption near edge structure

    DOE PAGES

    zhang, Bangmin; Chen, Jingsheng; Venkatesan, T.; ...

    2016-01-28

    In this study, the Mn K edge X-ray absorption near edge structure (XANES) of Pr 0.67Sr 0.33MnO 3 films with different thicknesses on (001) LaAlO 3 substrate were measured, and the effects of strain relaxation on film properties were investigated. The films experienced in-plane compressive strain and out-of-plane tensile strain. Strain relaxation evolved with the film thickness. In the polarization dependent XANES measurements, the in-plane (parallel) and out-of-plane (perpendicular) XANES spectrocopies were anisotropic with different absorption energy E r. The resonance energy Er along two directions shifted towards each other with increasing film thickness. Based on the X-ray diffraction results,more » it was suggested that the strain relaxation weakened the difference of the local environment and probability of electronic charge transfer (between Mn 3d and O 2p orbitals) along the in-plane and out-of-plane directions, which was responsible for the change of E r. XANES is a useful tool to probe the electronic structures, of which the effects on magnetic properties with the strain relaxation was also been studied.« less

  16. Lamb-Wave-Based Tomographic Imaging Techniques for Hole-Edge Corrosion Monitoring in Plate Structures

    PubMed Central

    Wang, Dengjiang; Zhang, Weifang; Wang, Xiangyu; Sun, Bo

    2016-01-01

    This study presents a novel monitoring method for hole-edge corrosion damage in plate structures based on Lamb wave tomographic imaging techniques. An experimental procedure with a cross-hole layout using 16 piezoelectric transducers (PZTs) was designed. The A0 mode of the Lamb wave was selected, which is sensitive to thickness-loss damage. The iterative algebraic reconstruction technique (ART) method was used to locate and quantify the corrosion damage at the edge of the hole. Hydrofluoric acid with a concentration of 20% was used to corrode the specimen artificially. To estimate the effectiveness of the proposed method, the real corrosion damage was compared with the predicted corrosion damage based on the tomographic method. The results show that the Lamb-wave-based tomographic method can be used to monitor the hole-edge corrosion damage accurately. PMID:28774041

  17. Optical Assessment of Soft Contact Lens Edge-Thickness.

    PubMed

    Tankam, Patrice; Won, Jungeun; Canavesi, Cristina; Cox, Ian; Rolland, Jannick P

    2016-08-01

    To assess the edge shape of soft contact lenses using Gabor-Domain Optical Coherence Microscopy (GD-OCM) with a 2-μm imaging resolution in three dimensions and to generate edge-thickness profiles at different distances from the edge tip of soft contact lenses. A high-speed custom-designed GD-OCM system was used to produce 3D images of the edge of an experimental soft contact lens (Bausch + Lomb, Rochester, NY) in four different configurations: in air, submerged into water, submerged into saline with contrast agent, and placed onto the cornea of a porcine eyeball. An algorithm to compute the edge-thickness was developed and applied to cross-sectional images. The proposed algorithm includes the accurate detection of the interfaces between the lens and the environment, and the correction of the refraction error. The sharply defined edge tip of a soft contact lens was visualized in 3D. Results showed precise thickness measurement of the contact lens edge profile. Fifty cross-sectional image frames for each configuration were used to test the robustness of the algorithm in evaluating the edge-thickness at any distance from the edge tip. The precision of the measurements was less than 0.2 μm. The results confirmed the ability of GD-OCM to provide high-definition images of soft contact lens edges. As a nondestructive, precise, and fast metrology tool for soft contact lens measurement, the integration of GD-OCM in the design and manufacturing of contact lenses will be beneficial for further improvement in edge design and quality control. In the clinical perspective, the in vivo evaluation of the lens fitted onto the cornea will advance our understanding of how the edge interacts with the ocular surface. The latter will provide insights into the impact of long-term use of contact lenses on the visual performance.

  18. Optical Assessment of Soft Contact Lens Edge-Thickness

    PubMed Central

    Tankam, Patrice; Won, Jungeun; Canavesi, Cristina; Cox, Ian; Rolland, Jannick P.

    2016-01-01

    Purpose To assess the edge shape of soft contact lenses using Gabor-Domain Optical Coherence Microscopy (GD-OCM) with a 2 μm imaging resolution in three dimensions, and to generate edge-thickness profiles at different distances from the edge tip of soft contact lenses. Methods A high-speed custom-designed GD-OCM system was used to produce 3D images of the edge of an experimental soft contact lens (Bausch + Lomb, Rochester NY) in four different configurations: in air, submerged into water, submerged into saline with contrast agent, and placed onto the cornea of a porcine eyeball. An algorithm to compute the edge-thickness was developed and applied to cross-sectional images. The proposed algorithm includes the accurate detection of the interfaces between the lens and the environment, and the correction of the refraction error. Results The sharply defined edge tip of a soft contact lens was visualized in 3D. Results showed precise thickness measurement of the contact lens edge profile. 50 cross-sectional image frames for each configuration were used to test the robustness of the algorithm in evaluating the edge-thickness at any distance from the edge tip. The precision of the measurements was less than 0.2 μm. Conclusions The results confirmed the ability of GD-OCM to provide high definition images of soft contact lens edges. As a non-destructive, precise, and fast metrology tool for soft contact lens measurement, the integration of GD-OCM in the design and manufacturing of contact lenses will be beneficial for further improvement in edge design and quality control. In the clinical perspective, the in-vivo evaluation of the lens fitted onto the cornea will advance our understanding of how the edge interacts with the ocular surface. The latter will provide insights into the impact of long-term use of contact lenses on the visual performance. PMID:27232902

  19. Selective sensitivity of Mueller imaging for tissue scattering over absorption changes in cancer mimicking phantoms

    NASA Astrophysics Data System (ADS)

    Fathima, Adeeba; Sharma B. S., Mahima; N., Sujatha

    2018-03-01

    Tissue characterization using optical polarimetry, especially Mueller imaging is receiving sustained interest due to its potential in achieving optical contrast between normal and malignant variations. This is particularly important in identifying the margin of malignant growth in suspected tissue regions for accurate surgical removal, or in aiding the sampling procedure during biopsy. The sensitivity of Mueller matrix derived depolarization index to the combined effects of changes in scattering and absorption occurring in a cancerous growth is illustrated in this study. Depolarization imaging is shown to be useful in demarcating the boundary of two regions of differing optical properties using a tissue phantom, modeled according to the changes expected during cancerous growth in tissue. Tissue scattering and absorption are expected to generally increase with the nuclear size change and crowding as well as angiogenesis associated with malignancy. We have observed that there is selective sensitivity for the Mueller elements and derived depolarization index to tissue scattering over absorption in the object field. Although the scattering and absorption are expected to increase and decrease depolarization respectively, the optical contrast of Mueller images and the derived depolarization index between normal and cancerous tissue is found appreciable in this region.

  20. Images

    Science.gov Websites

    : Upload Date Photo Date 1 2 3 4 5 Next Arctic Edge 2018 Download Full Image Photo Details Arctic Edge 2018 Download Full Image Photo Details Arctic Edge 2018 Download Full Image Photo Details Arctic Edge 2018 Download Full Image Photo Details Arctic Edge 2018 Download Full Image Photo Details Arctic Edge 2018

  1. Classification by diagnosing all absorption features (CDAF) for the most abundant minerals in airborne hyperspectral images

    NASA Astrophysics Data System (ADS)

    Mobasheri, Mohammad Reza; Ghamary-Asl, Mohsen

    2011-12-01

    Imaging through hyperspectral technology is a powerful tool that can be used to spectrally identify and spatially map materials based on their specific absorption characteristics in electromagnetic spectrum. A robust method called Tetracorder has shown its effectiveness at material identification and mapping, using a set of algorithms within an expert system decision-making framework. In this study, using some stages of Tetracorder, a technique called classification by diagnosing all absorption features (CDAF) is introduced. This technique enables one to assign a class to the most abundant mineral in each pixel with high accuracy. The technique is based on the derivation of information from reflectance spectra of the image. This can be done through extraction of spectral absorption features of any minerals from their respected laboratory-measured reflectance spectra, and comparing it with those extracted from the pixels in the image. The CDAF technique has been executed on the AVIRIS image where the results show an overall accuracy of better than 96%.

  2. Real-time biscuit tile image segmentation method based on edge detection.

    PubMed

    Matić, Tomislav; Aleksi, Ivan; Hocenski, Željko; Kraus, Dieter

    2018-05-01

    In this paper we propose a novel real-time Biscuit Tile Segmentation (BTS) method for images from ceramic tile production line. BTS method is based on signal change detection and contour tracing with a main goal of separating tile pixels from background in images captured on the production line. Usually, human operators are visually inspecting and classifying produced ceramic tiles. Computer vision and image processing techniques can automate visual inspection process if they fulfill real-time requirements. Important step in this process is a real-time tile pixels segmentation. BTS method is implemented for parallel execution on a GPU device to satisfy the real-time constraints of tile production line. BTS method outperforms 2D threshold-based methods, 1D edge detection methods and contour-based methods. Proposed BTS method is in use in the biscuit tile production line. Copyright © 2018 ISA. Published by Elsevier Ltd. All rights reserved.

  3. Multispectral imaging of absorption and scattering properties of in vivo exposed rat brain using a digital red-green-blue camera.

    PubMed

    Yoshida, Keiichiro; Nishidate, Izumi; Ishizuka, Tomohiro; Kawauchi, Satoko; Sato, Shunichi; Sato, Manabu

    2015-05-01

    In order to estimate multispectral images of the absorption and scattering properties in the cerebral cortex of in vivo rat brain, we investigated spectral reflectance images estimated by the Wiener estimation method using a digital RGB camera. A Monte Carlo simulation-based multiple regression analysis for the corresponding spectral absorbance images at nine wavelengths (500, 520, 540, 560, 570, 580, 600, 730, and 760 nm) was then used to specify the absorption and scattering parameters of brain tissue. In this analysis, the concentrations of oxygenated hemoglobin and that of deoxygenated hemoglobin were estimated as the absorption parameters, whereas the coefficient a and the exponent b of the reduced scattering coefficient spectrum approximated by a power law function were estimated as the scattering parameters. The spectra of absorption and reduced scattering coefficients were reconstructed from the absorption and scattering parameters, and the spectral images of absorption and reduced scattering coefficients were then estimated. In order to confirm the feasibility of this method, we performed in vivo experiments on exposed rat brain. The estimated images of the absorption coefficients were dominated by the spectral characteristics of hemoglobin. The estimated spectral images of the reduced scattering coefficients had a broad scattering spectrum, exhibiting a larger magnitude at shorter wavelengths, corresponding to the typical spectrum of brain tissue published in the literature. The changes in the estimated absorption and scattering parameters during normoxia, hyperoxia, and anoxia indicate the potential applicability of the method by which to evaluate the pathophysiological conditions of in vivo brain due to the loss of tissue viability.

  4. Temperature dependence of pre-edge features in Ti K-edge XANES spectra for ATiO₃ (A = Ca and Sr), A₂TiO₄ (A = Mg and Fe), TiO₂ rutile and TiO₂ anatase.

    PubMed

    Hiratoko, Tatsuya; Yoshiasa, Akira; Nakatani, Tomotaka; Okube, Maki; Nakatsuka, Akihiko; Sugiyama, Kazumasa

    2013-07-01

    XANES (X-ray absorption near-edge structure) spectra of the Ti K-edges of ATiO3 (A = Ca and Sr), A2TiO4 (A = Mg and Fe), TiO2 rutile and TiO2 anatase were measured in the temperature range 20-900 K. Ti atoms for all samples were located in TiO6 octahedral sites. The absorption intensity invariant point (AIIP) was found to be between the pre-edge and post-edge. After the AIIP, amplitudes damped due to Debye-Waller factor effects with temperature. Amplitudes in the pre-edge region increased with temperature normally by thermal vibration. Use of the AIIP peak intensity as a standard point enables a quantitative comparison of the intensity of the pre-edge peaks in various titanium compounds over a wide temperature range.

  5. Imaging the Impact of Proton Irradiation on Edge Terminations in Vertical GaN pin Diodes

    DOE PAGES

    Collins, Kimberlee C.; King, Michael P.; Dickerson, Jeramy R.; ...

    2017-05-29

    Devices based on GaN have shown great promise for high power electronics, including their potential use as radiation tolerant components. An important step to realizing high power diodes is the design and implementation of an edge termination to mitigate field crowding, which can lead to premature breakdown. However, little is known about the effects of radiation on edge termination functionality. We experimentally examine the effects of proton irradiation on multiple field ring edge terminations in high power vertical GaN pin diodes using in operando imaging with electron beam induced current (EBIC). We find that exposure to proton irradiation influences fieldmore » spreading in the edge termination as well as carrier transport near the anode. By using depth-dependent EBIC measurements of hole diffusion length in homoepitaxial n-GaN we demonstrate that the carrier transport effect is due to a reduction in hole diffusion length following proton irradiation.« less

  6. Imaging the Impact of Proton Irradiation on Edge Terminations in Vertical GaN pin Diodes

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Collins, Kimberlee C.; King, Michael P.; Dickerson, Jeramy R.

    Devices based on GaN have shown great promise for high power electronics, including their potential use as radiation tolerant components. An important step to realizing high power diodes is the design and implementation of an edge termination to mitigate field crowding, which can lead to premature breakdown. However, little is known about the effects of radiation on edge termination functionality. We experimentally examine the effects of proton irradiation on multiple field ring edge terminations in high power vertical GaN pin diodes using in operando imaging with electron beam induced current (EBIC). We find that exposure to proton irradiation influences fieldmore » spreading in the edge termination as well as carrier transport near the anode. By using depth-dependent EBIC measurements of hole diffusion length in homoepitaxial n-GaN we demonstrate that the carrier transport effect is due to a reduction in hole diffusion length following proton irradiation.« less

  7. Segmentation via fusion of edge and needle map

    NASA Astrophysics Data System (ADS)

    Ahn, Hong-Young; Tou, Julius T.

    1991-03-01

    This paper presents an integrated image segmentation method using edge and needle map which compensates deficiencies of using either edge-based approach or region-based approach. Segmentation of an image is the first and most difficult step toward symbolic transformation of a raw image, which is essential in image understanding. In industrial applications, the task is further complicated by the ubiquitous presence of specularity in most industrial parts. Three images taken from three different illumination directions were used to separate specular and Lambertian components in the images. Needle map is generated from Lambertian component images using photometric stereo technique. In one channel, edges are extracted and linked from the averaged Lambertian images providing one source of segmentation. The other channel, Gaussian curvature and mean curvature values are estimated at each pixel from least square local surface fit of needle map. Labeled surface type image is then generated using the signs of Gaussian and mean curvatures, where one of ten surface types is assigned to each pixel. Connected regions of identical surface type pixels provide the first level grouping, a rough initial segmentation. Edge information and initial segmentation of surface type are fed to an integration module which interprets the edges and regions in a consistent way. During interpretation regions are merged or split, edges are discarded or generated depending upon global surface fit error and consistency with neighboring regions. The output of integrated segmentation is an explicit description of surface type and contours of each region which facilitates recognition, localization and attitude determination of objects in the image.

  8. Structural evolution of fluorinated graphene upon molten-alkali treatment probed by X-ray absorption near-edge structure spectroscopy

    NASA Astrophysics Data System (ADS)

    Liang, Xianqing; Pan, Deyou; Lao, Ming; Liang, Shuiying; Huang, Dan; Zhou, Wenzheng; Guo, Jin

    2017-05-01

    The structural evolution of fluorinated graphene (FG) nanosheets upon molten-alkali treatment has been systematically investigated utilizing X-ray absorption near-edge structure (XANES) spectroscopy. It is found that the hydroxyl groups can progressively displace fluorine atoms to form covalent bonds to the graphene sheets under designed molten-alkali condition. The XANES spectra also reveal the formation of epoxide groups through intramolecular dehydration of neighbouring hydroxyl groups after substitution reaction. At high alkali-FG weight ratio, the restoration of the π-conjugated structure in graphene sheets can be observed due to the gradual decomposition of epoxide groups. Our experimental results indicate that the surface chemistry and electronic structure of hydroxyl-functionalized FG (HFG) can be readily tuned by varying the ratio of reactants.

  9. Near-Edge X-ray Absorption Fine Structure Studies of Electrospun Poly(dimethylsiloxane)/Poly (methyl methacrylate)/Multiwall Carbon Nanotube Composites

    PubMed Central

    Winter, A. Douglas; Larios, Eduardo; Alamgir, Faisal M.; Jaye, Cherno; Fischer, Daniel; Campo, Eva M.

    2014-01-01

    This work describes the near conduction band edge structure of electrospun mats of MWCNT-PDMS-PMMA by near edge X-Ray absorption fine structure (NEXAFS) spectroscopy. Effects of adding nanofillers of different sizes were addressed. Despite observed morphological variations and inhomogeneous carbon nanotube distribution, spun mats appeared homogeneous under NEXAFS analysis. Spectra revealed differences in emissions from glancing and normal spectra; which may evidence phase separation within the bulk of the micron-size fibers. Further, dichroic ratios show polymer chains did not align, even in the presence of nanofillers. Addition of nanofillers affected emissions in the C-H, C=O and C-C regimes, suggesting their involvement in interfacial matrix-carbon nanotube bonding. Spectral differences at glancing angles between pristine and composite mats suggest that geometric conformational configurations are taking place between polymeric chains and carbon nanotubes. These differences appear to be carbon nanotube-dimension dependent, and are promoted upon room temperature mixing and shear flow during electrospinning. CH-π bonding between polymer chains and graphitic walls, as well as H-bonds between impurities in the as-grown CNTs and polymer pendant groups are proposed bonding mechanisms promoting matrix conformation. PMID:24308286

  10. X-ray absorption edge spectroscopy and computational studies on LCuO2 species: Superoxide-Cu(II) versus peroxide-Cu(III) bonding.

    PubMed

    Sarangi, Ritimukta; Aboelella, Nermeen; Fujisawa, Kiyoshi; Tolman, William B; Hedman, Britt; Hodgson, Keith O; Solomon, Edward I

    2006-06-28

    The geometric and electronic structures of two mononuclear CuO2 complexes, [Cu(O2){HB(3-Ad-5-(i)Prpz)3}] (1) and [Cu(O2)(beta-diketiminate)] (2), have been evaluated using Cu K- and L-edge X-ray absorption spectroscopy (XAS) studies in combination with valence bond configuration interaction (VBCI) simulations and spin-unrestricted broken symmetry density functional theory (DFT) calculations. Cu K- and L-edge XAS data indicate the Cu(II) and Cu(III) nature of 1 and 2, respectively. The total integrated intensity under the L-edges shows that the 's in 1 and 2 contain 20% and 28% Cu character, respectively, indicative of very covalent ground states in both complexes, although more so in 1. Two-state VBCI simulations also indicate that the ground state in 2 has more Cu (/3d8) character. DFT calculations show that the in both complexes is dominated by O2(n-) character, although the O2(n-) character is higher in 1. It is shown that the ligand L plays an important role in modulating Cu-O2 bonding in these LCuO2 systems and tunes the ground states of 1 and 2 to have dominant Cu(II)-superoxide-like and Cu(III)-peroxide-like character, respectively. The contributions of ligand field (LF) and the charge on the absorbing atom in the molecule (Q(mol)M) to L- and K-edge energy shifts are evaluated using DFT and time-dependent DFT calculations. It is found that LF makes a dominant contribution to the edge energy shift, while the effect of Q(mol)M is minor. The charge on the Cu in the Cu(III) complex is found to be similar to that in Cu(II) complexes, which indicates a much stronger interaction with the ligand, leading to extensive charge transfer.

  11. Near sulfur L-edge X-ray absorption spectra of methanethiol in isolation and adsorbed on a Au(111) surface: a theoretical study using the four-component static exchange approximation.

    PubMed

    Villaume, Sebastien; Ekström, Ulf; Ottosson, Henrik; Norman, Patrick

    2010-06-07

    The relativistic four-component static exchange approach for calculation of near-edge X-ray absorption spectra has been reviewed. Application of the method is made to the Au(111) interface and the adsorption of methanethiol by a study of the near sulfur L-edge spectrum. The binding energies of the sulfur 2p(1/2) and 2p(3/2) sublevels in methanethiol are determined to be split by 1.2 eV due to spin-orbit coupling, and the binding energy of the 2p(3/2) shell is lowered from 169.2 eV for the isolated system to 167.4 and 166.7-166.8 eV for methanethiol in mono- and di-coordinated adsorption sites, respectively (with reference to vacuum). In the near L-edge X-ray absorption fine structure spectrum only the sigma*(S-C) peak at 166 eV remains intact by surface adsorption, whereas transitions of predominantly Rydberg character are largely quenched in the surface spectra. The sigma*(S-H) peak of methanethiol is replaced by low-lying, isolated, sigma*(S-Au) peak(s), where the number of peaks in the latter category and their splittings are characteristic of the local bonding situation of the sulfur.

  12. Optimal frequency domain textural edge detection filter

    NASA Technical Reports Server (NTRS)

    Townsend, J. K.; Shanmugan, K. S.; Frost, V. S.

    1985-01-01

    An optimal frequency domain textural edge detection filter is developed and its performance evaluated. For the given model and filter bandwidth, the filter maximizes the amount of output image energy placed within a specified resolution interval centered on the textural edge. Filter derivation is based on relating textural edge detection to tonal edge detection via the complex low-pass equivalent representation of narrowband bandpass signals and systems. The filter is specified in terms of the prolate spheroidal wave functions translated in frequency. Performance is evaluated using the asymptotic approximation version of the filter. This evaluation demonstrates satisfactory filter performance for ideal and nonideal textures. In addition, the filter can be adjusted to detect textural edges in noisy images at the expense of edge resolution.

  13. 2D Doppler backscattering using synthetic aperture microwave imaging of MAST edge plasmas

    NASA Astrophysics Data System (ADS)

    Thomas, D. A.; Brunner, K. J.; Freethy, S. J.; Huang, B. K.; Shevchenko, V. F.; Vann, R. G. L.

    2016-02-01

    Doppler backscattering (DBS) is already established as a powerful diagnostic; its extension to 2D enables imaging of turbulence characteristics from an extended region of the cut-off surface. The Synthetic Aperture Microwave Imaging (SAMI) diagnostic has conducted proof-of-principle 2D DBS experiments of MAST edge plasma. SAMI actively probes the plasma edge using a wide (±40° vertical and horizontal) and tuneable (10-34.5 GHz) beam. The Doppler backscattered signal is digitised in vector form using an array of eight Vivaldi PCB antennas. This allows the receiving array to be focused in any direction within the field of view simultaneously to an angular range of 6-24° FWHM at 10-34.5 GHz. This capability is unique to SAMI and is a novel way of conducting DBS experiments. In this paper the feasibility of conducting 2D DBS experiments is explored. Initial observations of phenomena previously measured by conventional DBS experiments are presented; such as momentum injection from neutral beams and an abrupt change in power and turbulence velocity coinciding with the onset of H-mode. In addition, being able to carry out 2D DBS imaging allows a measurement of magnetic pitch angle to be made; preliminary results are presented. Capabilities gained through steering a beam using a phased array and the limitations of this technique are discussed.

  14. Three-dimensional contour edge detection algorithm

    NASA Astrophysics Data System (ADS)

    Wang, Yizhou; Ong, Sim Heng; Kassim, Ashraf A.; Foong, Kelvin W. C.

    2000-06-01

    This paper presents a novel algorithm for automatically extracting 3D contour edges, which are points of maximum surface curvature in a surface range image. The 3D image data are represented as a surface polygon mesh. The algorithm transforms the range data, obtained by scanning a dental plaster cast, into a 2D gray scale image by linearly converting the z-value of each vertex to a gray value. The Canny operator is applied to the median-filtered image to obtain the edge pixels and their orientations. A vertex in the 3D object corresponding to the detected edge pixel and its neighbors in the direction of the edge gradient are further analyzed with respect to their n-curvatures to extract the real 3D contour edges. This algorithm provides a fast method of reducing and sorting the unwieldy data inherent in the surface mesh representation. It employs powerful 2D algorithms to extract features from the transformed 3D models and refers to the 3D model for further analysis of selected data. This approach substantially reduces the computational burden without losing accuracy. It is also easily extended to detect 3D landmarks and other geometrical features, thus making it applicable to a wide range of applications.

  15. Photoabsorption study of Bacillus megaterium, DNA and Related Biological Materials in the Phosphorus K-edge Region

    NASA Technical Reports Server (NTRS)

    Frigo, Sean P.; McNulty,Ian; Richmond, Robert C.; Ehret, Charles F.

    2003-01-01

    We have measured the x-ray transmission spectra of several biologically related samples in the phosphorus K-edge absorption region. These include red phosphorus, hydrated sodium phosphate (Na3PO4 12 H2O), deoxyribonucleic acid (DNA), adenosinetriphosphate (ATP), diolylphosphatidyl choline (DOPC), and Bacillus megaterium spores. Red phosphorus essentially displays an edge-jump. All other spectra are similar in form and energy position, where each is dominated by a narrower, more intense first peak and a broader but less intense second peak. The corresponding K-edge absorption thresholds are shifted towards higher energy relative to that for red phosphorus, as expected for increasing degrees of phosphorus oxidation. The B.meguterium spectrum has aspects common to both the phosphate and DNA spectra and is therefore interpreted as a composite of spectra arising from DNA/RNA and phosphates within the spore. The B. megaterium spore spectrum provides needed information for resonant radiation damage studies in the phosphorus K-edge absorption region by identifying candidate photoexcitations. In addition, the absorption spectra will be useful in macromolecular crystallography studies employing anomalous dispersion effects at the phosphorus K-edge.

  16. Photoabsorption Study of Bacillus megaterium, DNA and Related Biological Materials in the Phosphorus K-edge Region

    NASA Technical Reports Server (NTRS)

    Frigo, Sean P.; McNulty, Ian; Richmond, Robert C.; Ehret, Charles F.

    2002-01-01

    We have measured the x-ray transmission spectra of several biologically related samples in the phosphorus K-edge absorption region. These include elemental red phosphorus, hydrated sodium phosphate (Na3PO4.12H2O), deoxyribonucleic acid (DNA), adenosinetriphosphate (ATP), diolylphosphatidyl choline (DOPC), and Bacillus megaterium spores. Elemental red phosphorus essentially displays an edge-jump. All other spectra are similar in form and energy position. Each spectrum for these substances is dominated by a narrower, more intense first peak and a broader but less intense second peak. The corresponding K-edge absorption thresholds are shifted towards higher energy relative to that for elemental red phosphorus, as expected for increasing degrees of phosphorus oxidation. The B. megaterium spectrum has aspects common to both the phosphate and DNA spectra and is therefore interpreted as a composite of spectra arising from DNA/RNA and phosphates within the spore. The B. megaterium spore spectrum provides needed information for resonant radiation damage studies in the phosphorus K-edge absorption region by identifying candidate photoexcitations. In addition,the absorption spectra will be useful in macromolecular crystallography studies employing anomalous dispersion effects at the phosphorus K-edge.

  17. Forensic applications of chemical imaging: latent fingerprint detection using visible absorption and luminescence.

    PubMed

    Exline, David L; Wallace, Christie; Roux, Claude; Lennard, Chris; Nelson, Matthew P; Treado, Patrick J

    2003-09-01

    Chemical imaging technology is a rapid examination technique that combines molecular spectroscopy and digital imaging, providing information on morphology, composition, structure, and concentration of a material. Among many other applications, chemical imaging offers an array of novel analytical testing methods, which limits sample preparation and provides high-quality imaging data essential in the detection of latent fingerprints. Luminescence chemical imaging and visible absorbance chemical imaging have been successfully applied to ninhydrin, DFO, cyanoacrylate, and luminescent dye-treated latent fingerprints, demonstrating the potential of this technology to aid forensic investigations. In addition, visible absorption chemical imaging has been applied successfully to visualize untreated latent fingerprints.

  18. Transmission X-ray microscopy for full-field nano-imaging of biomaterials

    PubMed Central

    ANDREWS, JOY C; MEIRER, FLORIAN; LIU, YIJIN; MESTER, ZOLTAN; PIANETTA, PIERO

    2010-01-01

    Imaging of cellular structure and extended tissue in biological materials requires nanometer resolution and good sample penetration, which can be provided by current full-field transmission X-ray microscopic techniques in the soft and hard X-ray regions. The various capabilities of full-field transmission X-ray microscopy (TXM) include 3D tomography, Zernike phase contrast, quantification of absorption, and chemical identification via X-ray fluorescence and X-ray absorption near edge structure (XANES) imaging. These techniques are discussed and compared in light of results from imaging of biological materials including microorganisms, bone and mineralized tissue and plants, with a focus on hard X-ray TXM at ≤ 40 nm resolution. PMID:20734414

  19. Transmission X-ray microscopy for full-field nano imaging of biomaterials.

    PubMed

    Andrews, Joy C; Meirer, Florian; Liu, Yijin; Mester, Zoltan; Pianetta, Piero

    2011-07-01

    Imaging of cellular structure and extended tissue in biological materials requires nanometer resolution and good sample penetration, which can be provided by current full-field transmission X-ray microscopic techniques in the soft and hard X-ray regions. The various capabilities of full-field transmission X-ray microscopy (TXM) include 3D tomography, Zernike phase contrast, quantification of absorption, and chemical identification via X-ray fluorescence and X-ray absorption near edge structure imaging. These techniques are discussed and compared in light of results from the imaging of biological materials including microorganisms, bone and mineralized tissue, and plants, with a focus on hard X-ray TXM at ≤ 40-nm resolution. Copyright © 2010 Wiley-Liss, Inc.

  20. An Adaptive Immune Genetic Algorithm for Edge Detection

    NASA Astrophysics Data System (ADS)

    Li, Ying; Bai, Bendu; Zhang, Yanning

    An adaptive immune genetic algorithm (AIGA) based on cost minimization technique method for edge detection is proposed. The proposed AIGA recommends the use of adaptive probabilities of crossover, mutation and immune operation, and a geometric annealing schedule in immune operator to realize the twin goals of maintaining diversity in the population and sustaining the fast convergence rate in solving the complex problems such as edge detection. Furthermore, AIGA can effectively exploit some prior knowledge and information of the local edge structure in the edge image to make vaccines, which results in much better local search ability of AIGA than that of the canonical genetic algorithm. Experimental results on gray-scale images show the proposed algorithm perform well in terms of quality of the final edge image, rate of convergence and robustness to noise.

  1. MO-FG-204-03: Using Edge-Preserving Algorithm for Significantly Improved Image-Domain Material Decomposition in Dual Energy CT

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zhao, W; Niu, T; Xing, L

    2015-06-15

    Purpose: To significantly improve dual energy CT (DECT) imaging by establishing a new theoretical framework of image-domain material decomposition with incorporation of edge-preserving techniques. Methods: The proposed algorithm, HYPR-NLM, combines the edge-preserving non-local mean filter (NLM) with the HYPR-LR (Local HighlY constrained backPRojection Reconstruction) framework. Image denoising using HYPR-LR framework depends on the noise level of the composite image which is the average of the different energy images. For DECT, the composite image is the average of high- and low-energy images. To further reduce noise, one may want to increase the window size of the filter of the HYPR-LR, leadingmore » resolution degradation. By incorporating the NLM filtering and the HYPR-LR framework, HYPR-NLM reduces the boost material decomposition noise using energy information redundancies as well as the non-local mean. We demonstrate the noise reduction and resolution preservation of the algorithm with both iodine concentration numerical phantom and clinical patient data by comparing the HYPR-NLM algorithm to the direct matrix inversion, HYPR-LR and iterative image-domain material decomposition (Iter-DECT). Results: The results show iterative material decomposition method reduces noise to the lowest level and provides improved DECT images. HYPR-NLM significantly reduces noise while preserving the accuracy of quantitative measurement and resolution. For the iodine concentration numerical phantom, the averaged noise levels are about 2.0, 0.7, 0.2 and 0.4 for direct inversion, HYPR-LR, Iter- DECT and HYPR-NLM, respectively. For the patient data, the noise levels of the water images are about 0.36, 0.16, 0.12 and 0.13 for direct inversion, HYPR-LR, Iter-DECT and HYPR-NLM, respectively. Difference images of both HYPR-LR and Iter-DECT show edge effect, while no significant edge effect is shown for HYPR-NLM, suggesting spatial resolution is well preserved for HYPR-NLM. Conclusion

  2. Edge of polar cap patches

    NASA Astrophysics Data System (ADS)

    Hosokawa, K.; Taguchi, S.; Ogawa, Y.

    2016-04-01

    On the night of 4 December 2013, a sequence of polar cap patches was captured by an all-sky airglow imager (ASI) in Longyearbyen, Norway (78.1°N, 15.5°E). The 630.0 nm airglow images from the ASI of 4 second exposure time, oversampled the emission of natural lifetime (with quenching) of at least ˜30 sec, introduce no observational blurring effects. By using such high-quality ASI images, we succeeded in visualizing an asymmetry in the gradients between the leading/trailing edges of the patches in a 2-D fashion. The gradient in the leading edge was found to be 2-3 times steeper than that in the trailing edge. We also identified fingerlike structures, appearing only along the trailing edge of the patches, whose horizontal scale size ranged from 55 to 210 km. These fingers are considered to be manifestations of plasma structuring through the gradient-drift instability (GDI), which is known to occur only along the trailing edge of patches. That is, the current 2-D observations visualized, for the first time, how GDI stirs the patch plasma and such a mixing process makes the trailing edge more gradual. This result strongly implies a close connection between the GDI-driven plasma stirring and the asymmetry in the large-scale shape of patches and then suggests that the fingerlike structures can be used as markers to estimate the fine-scale structure in the plasma flow within patches.

  3. Thermal emission and absorption of radiation in finite inverted-opal photonic crystals

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Florescu, Marian; Stimpson, Andrew J.; Lee, Hwang

    We study theoretically the optical properties of a finite inverted-opal photonic crystal. The light-matter interaction is strongly affected by the presence of the three-dimensional photonic crystal and the alterations of the light emission and absorption processes can be used to suppress or enhance the thermal emissivity and absorptivity of the dielectric structure. We investigate the influence of the absorption present in the system on the relevant band edge frequencies that control the optical response of the photonic crystal. Our study reveals that the absorption processes cause spectral broadening and shifting of the band edge optical resonances, and determine a strongmore » reduction of the photonic band gap spectral range. Using the angular and spectral dependence of the band edge frequencies for stop bands along different directions, we argue that by matching the blackbody emission spectrum peak with a prescribed maximum of the absorption coefficient, it is possible to achieve an angle-sensitive enhancement of the thermal emission/absorption of radiation. This result opens a way to realize a frequency-sensitive and angle-sensitive photonic crystal absorbers/emitters.« less

  4. Segmentation of brain volume based on 3D region growing by integrating intensity and edge for image-guided surgery

    NASA Astrophysics Data System (ADS)

    Tsagaan, Baigalmaa; Abe, Keiichi; Goto, Masahiro; Yamamoto, Seiji; Terakawa, Susumu

    2006-03-01

    This paper presents a segmentation method of brain tissues from MR images, invented for our image-guided neurosurgery system under development. Our goal is to segment brain tissues for creating biomechanical model. The proposed segmentation method is based on 3-D region growing and outperforms conventional approaches by stepwise usage of intensity similarities between voxels in conjunction with edge information. Since the intensity and the edge information are complementary to each other in the region-based segmentation, we use them twice by performing a coarse-to-fine extraction. First, the edge information in an appropriate neighborhood of the voxel being considered is examined to constrain the region growing. The expanded region of the first extraction result is then used as the domain for the next processing. The intensity and the edge information of the current voxel only are utilized in the final extraction. Before segmentation, the intensity parameters of the brain tissues as well as partial volume effect are estimated by using expectation-maximization (EM) algorithm in order to provide an accurate data interpretation into the extraction. We tested the proposed method on T1-weighted MR images of brain and evaluated the segmentation effectiveness comparing the results with ground truths. Also, the generated meshes from the segmented brain volume by using mesh generating software are shown in this paper.

  5. A new method of edge detection for object recognition

    USGS Publications Warehouse

    Maddox, Brian G.; Rhew, Benjamin

    2004-01-01

    Traditional edge detection systems function by returning every edge in an input image. This can result in a large amount of clutter and make certain vectorization algorithms less accurate. Accuracy problems can then have a large impact on automated object recognition systems that depend on edge information. A new method of directed edge detection can be used to limit the number of edges returned based on a particular feature. This results in a cleaner image that is easier for vectorization. Vectorized edges from this process could then feed an object recognition system where the edge data would also contain information as to what type of feature it bordered.

  6. K- and L-edge X-ray absorption spectroscopy (XAS) and resonant inelastic X-ray scattering (RIXS) determination of differential orbital covalency (DOC) of transition metal sites

    DOE PAGES

    Baker, Michael L.; Mara, Michael W.; Yan, James J.; ...

    2017-02-09

    Continual advancements in the development of synchrotron radiation sources have resulted in X-ray based spectroscopic techniques capable of probing the electronic and structural properties of numerous systems. This review gives an overview of the application of metal K-edge and L-edge X-ray absorption spectroscopy (XAS), as well as Kα resonant inelastic X-ray scattering (RIXS), to the study of electronic structure in transition metal sites with emphasis on experimentally quantifying 3d orbital covalency. The specific sensitivities of K-edge XAS, L-edge XAS, and RIXS are discussed emphasizing the complementary nature of the methods. L-edge XAS and RIXS are sensitive to mixing between 3dmore » orbitals and ligand valence orbitals, and to the differential orbital covalency (DOC), that is, the difference in the covalencies for different symmetry sets of the d orbitals. Both L-edge XAS and RIXS are highly sensitive to and enable separation of σ and π donor bonding and π back bonding contributions to bonding. Applying ligand field multiplet simulations, including charge transfer via valence bond configuration interactions, DOC can be obtained for direct comparison with density functional theory calculations and to understand chemical trends. Here, the application of RIXS as a probe of frontier molecular orbitals in a heme enzyme demonstrates the potential of this method for the study of metal sites in highly covalent coordination sites in bioinorganic chemistry.« less

  7. K- and L-edge X-ray absorption spectroscopy (XAS) and resonant inelastic X-ray scattering (RIXS) determination of differential orbital covalency (DOC) of transition metal sites

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Baker, Michael L.; Mara, Michael W.; Yan, James J.

    Continual advancements in the development of synchrotron radiation sources have resulted in X-ray based spectroscopic techniques capable of probing the electronic and structural properties of numerous systems. This review gives an overview of the application of metal K-edge and L-edge X-ray absorption spectroscopy (XAS), as well as Kα resonant inelastic X-ray scattering (RIXS), to the study of electronic structure in transition metal sites with emphasis on experimentally quantifying 3d orbital covalency. The specific sensitivities of K-edge XAS, L-edge XAS, and RIXS are discussed emphasizing the complementary nature of the methods. L-edge XAS and RIXS are sensitive to mixing between 3dmore » orbitals and ligand valence orbitals, and to the differential orbital covalency (DOC), that is, the difference in the covalencies for different symmetry sets of the d orbitals. Both L-edge XAS and RIXS are highly sensitive to and enable separation of σ and π donor bonding and π back bonding contributions to bonding. Applying ligand field multiplet simulations, including charge transfer via valence bond configuration interactions, DOC can be obtained for direct comparison with density functional theory calculations and to understand chemical trends. Here, the application of RIXS as a probe of frontier molecular orbitals in a heme enzyme demonstrates the potential of this method for the study of metal sites in highly covalent coordination sites in bioinorganic chemistry.« less

  8. Interstellar X-Ray Absorption Spectroscopy of the Crab Pulsar with the LETGS

    NASA Technical Reports Server (NTRS)

    Paerels, Frits; Weisskopf, Martin C.; Tennant, Allyn F.; ODell, Stephen L.; Swartz, Douglas A.; Kahn, Steven M.; Behar, Ehud; Becker, Werner; Whitaker, Ann F. (Technical Monitor)

    2001-01-01

    We study the interstellar X-ray absorption along the line of sight to the Crab Pulsar. The Crab was observed with the Low Energy Transmission Grating Spectrometer on the Chandra X-ray Observatory, and the pulsar, a point source, produces a full resolution spectrum. The continuum spectrum appears smooth, and we compare its parameters with other measurements of the pulsar spectrum. The spectrum clearly shows absorption edges due to interstellar Ne, Fe, and O. The O edge shows spectral structure that is probably due to O bound in molecules or dust. We search for near-edge structure (EXAFS) in the O absorption spectrum. The Fe L absorption spectrum is largely due to a set of unresolved discrete n=2-3 transitions in neutral or near-neutral Fe, and we analyze it using a new set of dedicated atomic structure calculations, which provide absolute cross sections. In addition to being interesting in its own right, the ISM absorption needs to be understood in quantitative detail in order to derive spectroscopic constraints on possible soft thermal radiation from the pulsar.

  9. Evidence for Al/Si tetrahedral network in aluminosilicate glasses from Al K-edge x-ray-absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Wu, Ziyu; Romano, C.; Marcelli, A.; Mottana, A.; Cibin, G.; della Ventura, G.; Giuli, G.; Courtial, P.; Dingwell, D. B.

    1999-10-01

    The structure of aluminosilicate melts and/or glasses plays a key role in the earth sciences for the understanding of rock-forming igneous processes, as well as in the materials sciences for their technical applications. In particular, the alkaline-earth aluminosilicate glasses are an extremely important group of materials, with a wide range of commercial application, as well as serving as an analog for natural basaltic melts. However, definition of their structure and properties is still controversial, and in particular the role and effect of Al has long been a subject of debate. Here we report a series of experimental x-ray absorption near-edge structure spectra at the Al K edge on a series of synthetic glasses of peralkaline composition in the CaO-Al2O3-SiO2 system, together with a general theoretical framework for data analysis based on an ab initio full multiple-scattering theory. We propose an Al/Si tetrahedral network model for aluminosilicate glasses based on distorted polyhedra, with varying both the T-O (T=Al or Si) bond lengths and the T-O-T angles, and with different Al/Si composition. This model achieves a significant agreement between experiments and simulations. In these glasses, experimental data and theoretical results concur to support a model in which Al is network former with a comparatively well ordered local medium-range order (up to 5 Å).

  10. Edge grouping combining boundary and region information.

    PubMed

    Stahl, Joachim S; Wang, Song

    2007-10-01

    This paper introduces a new edge-grouping method to detect perceptually salient structures in noisy images. Specifically, we define a new grouping cost function in a ratio form, where the numerator measures the boundary proximity of the resulting structure and the denominator measures the area of the resulting structure. This area term introduces a preference towards detecting larger-size structures and, therefore, makes the resulting edge grouping more robust to image noise. To find the optimal edge grouping with the minimum grouping cost, we develop a special graph model with two different kinds of edges and then reduce the grouping problem to finding a special kind of cycle in this graph with a minimum cost in ratio form. This optimal cycle-finding problem can be solved in polynomial time by a previously developed graph algorithm. We implement this edge-grouping method, test it on both synthetic data and real images, and compare its performance against several available edge-grouping and edge-linking methods. Furthermore, we discuss several extensions of the proposed method, including the incorporation of the well-known grouping cues of continuity and intensity homogeneity, introducing a factor to balance the contributions from the boundary and region information, and the prevention of detecting self-intersecting boundaries.

  11. Computational study of the absorption spectrum of defected ZnS nanoparticles

    NASA Astrophysics Data System (ADS)

    Michos, F. I.; Sigalas, M. M.

    2018-04-01

    Energy levels and absorption spectra of defected ZnS nanoparticles (NPs) were calculated with Density Functional Theory (DFT) and Time Dependent DFT. Several types of defects were examined such as vacancies and substitutions. NPs with S vacancies were found to have their absorption spectra moved to lower energies well inside the visible spectrum with significantly high oscillator strength. Also, NPs with substitution of S atoms with Cl, Br, or I showed significant absorption. In general, this type of defect moves the absorption spectra in lower energies, thus bringing the absorption edge into the visible spectrum, while the unperturbed NPs have absorption edges in the UV region. In addition, ZnS NPs are made from more abundant and less toxic elements than the more commonly used CdSe NPs. For that reason, they may find significant applications in solar cells and other photonic applications, as well as in biosensing applications as biomarkers.

  12. Low-temperature adsorption of H2S on Ni(001) studied by near-edge- and surface-extended-x-ray-absorption fine structure

    NASA Astrophysics Data System (ADS)

    McGrath, R.; MacDowell, A. A.; Hashizume, T.; Sette, F.; Citrin, P. H.

    1989-11-01

    The adsorption of H2S on Ni(001) has been studied with surface-extended x-ray-absorption fine structure and near-edge x-ray-absorption fine structure (NEXAFS) using the AT&T Bell Laboratories X15B beamline at the National Synchrotron Light Source. At 95 K and full saturation coverage, ~0.45 monolayer (ML) of S atoms in fourfold-hollow sites are produced, characteristic of room-temperature adsorption, accompanied by ~0.05 ML of oriented molecular H2S. Both these atomic and molecular chemisorbed species are buried under ~0.9 ML of disordered physisorbed H2S. No evidence for HS is found. Above 190 K the two molecular H2S phases desorb, leaving only dissociated S. These findings differ from previously reported interpretations of data obtained with high-resolution electron-energy-loss spectroscopy. They also exemplify the utility of NEXAFS for identifying and quantifying atomic and molecular surface species even when their difference involves only H and the two species coexist.

  13. Sulfur species in source rock bitumen before and after hydrous pyrolysis determined by X-ray absorption near-edge structure

    USGS Publications Warehouse

    Bolin, Trudy B.; Birdwell, Justin E.; Lewan, Michael; Hill, Ronald J.; Grayson, Michael B.; Mitra-Kirtley, Sudipa; Bake, Kyle D.; Craddock, Paul R.; Abdallah, Wael; Pomerantz, Andrew E.

    2016-01-01

    The sulfur speciation of source rock bitumen (chloroform-extractable organic matter in sedimentary rocks) was examined using sulfur K-edge X-ray absorption near-edge structure (XANES) spectroscopy for a suite of 11 source rocks from around the world. Sulfur speciation was determined for both the native bitumen in thermally immature rocks and the bitumen produced by thermal maturation of kerogen via hydrous pyrolysis (360 °C for 72 h) and retained within the rock matrix. In this study, the immature bitumens had higher sulfur concentrations than those extracted from samples after hydrous pyrolysis. In addition, dramatic and systematic evolution of the bitumen sulfur moiety distributions following artificial thermal maturation was observed consistently for all samples. Specifically, sulfoxide sulfur (sulfur double bonded to oxygen) is abundant in all immature bitumen samples but decreases substantially following hydrous pyrolysis. The loss in sulfoxide sulfur is associated with a relative increase in the fraction of thiophene sulfur (sulfur bonded to aromatic carbon) to the extent that thiophene is the dominant sulfur form in all post-pyrolysis bitumen samples. This suggests that sulfur moiety distributions might be used for estimating thermal maturity in source rocks based on the character of the extractable organic matter.

  14. Effect of Edge-Preserving Adaptive Image Filter on Low-Contrast Detectability in CT Systems: Application of ROC Analysis

    PubMed Central

    Okumura, Miwa; Ota, Takamasa; Kainuma, Kazuhisa; Sayre, James W.; McNitt-Gray, Michael; Katada, Kazuhiro

    2008-01-01

    Objective. For the multislice CT (MSCT) systems with a larger number of detector rows, it is essential to employ dose-reduction techniques. As reported in previous studies, edge-preserving adaptive image filters, which selectively eliminate only the noise elements that are increased when the radiation dose is reduced without affecting the sharpness of images, have been developed. In the present study, we employed receiver operating characteristic (ROC) analysis to assess the effects of the quantum denoising system (QDS), which is an edge-preserving adaptive filter that we have developed, on low-contrast resolution, and to evaluate to what degree the radiation dose can be reduced while maintaining acceptable low-contrast resolution. Materials and Methods. The low-contrast phantoms (Catphan 412) were scanned at various tube current settings, and ROC analysis was then performed for the groups of images obtained with/without the use of QDS at each tube current to determine whether or not a target could be identified. The tube current settings for which the area under the ROC curve (Az value) was approximately 0.7 were determined for both groups of images with/without the use of QDS. Then, the radiation dose reduction ratio when QDS was used was calculated by converting the determined tube current to the radiation dose. Results. The use of the QDS edge-preserving adaptive image filter allowed the radiation dose to be reduced by up to 38%. Conclusion. The QDS was found to be useful for reducing the radiation dose without affecting the low-contrast resolution in MSCT studies. PMID:19043565

  15. Real-time edge-enhanced optical correlator

    NASA Technical Reports Server (NTRS)

    Liu, Tsuen-Hsi (Inventor); Cheng, Li-Jen (Inventor)

    1992-01-01

    Edge enhancement of an input image by four-wave mixing a first write beam with a second write beam in a photorefractive crystal, GaAs, was achieved for VanderLugt optical correlation with an edge enhanced reference image by optimizing the power ratio of a second write beam to the first write beam (70:1) and optimizing the power ratio of a read beam, which carries the reference image to the first write beam (100:701). Liquid crystal TV panels are employed as spatial light modulators to change the input and reference images in real time.

  16. A Novel Segmentation Approach Combining Region- and Edge-Based Information for Ultrasound Images

    PubMed Central

    Luo, Yaozhong; Liu, Longzhong; Li, Xuelong

    2017-01-01

    Ultrasound imaging has become one of the most popular medical imaging modalities with numerous diagnostic applications. However, ultrasound (US) image segmentation, which is the essential process for further analysis, is a challenging task due to the poor image quality. In this paper, we propose a new segmentation scheme to combine both region- and edge-based information into the robust graph-based (RGB) segmentation method. The only interaction required is to select two diagonal points to determine a region of interest (ROI) on the original image. The ROI image is smoothed by a bilateral filter and then contrast-enhanced by histogram equalization. Then, the enhanced image is filtered by pyramid mean shift to improve homogeneity. With the optimization of particle swarm optimization (PSO) algorithm, the RGB segmentation method is performed to segment the filtered image. The segmentation results of our method have been compared with the corresponding results obtained by three existing approaches, and four metrics have been used to measure the segmentation performance. The experimental results show that the method achieves the best overall performance and gets the lowest ARE (10.77%), the second highest TPVF (85.34%), and the second lowest FPVF (4.48%). PMID:28536703

  17. Confocal Microscopy Imaging with an Optical Transition Edge Sensor

    NASA Astrophysics Data System (ADS)

    Fukuda, D.; Niwa, K.; Hattori, K.; Inoue, S.; Kobayashi, R.; Numata, T.

    2018-05-01

    Fluorescence color imaging at an extremely low excitation intensity was performed using an optical transition edge sensor (TES) embedded in a confocal microscope for the first time. Optical TES has the ability to resolve incident single photon energy; therefore, the wavelength of each photon can be measured without spectroscopic elements such as diffraction gratings. As target objects, animal cells labeled with two fluorescent dyes were irradiated with an excitation laser at an intensity below 1 μW. In our confocal system, an optical fiber-coupled TES device is used to detect photons instead of the pinhole and photomultiplier tube used in typical confocal microscopes. Photons emitted from the dyes were collected by the objective lens, and sent to the optical TES via the fiber. The TES measures the wavelength of each photon arriving in an exposure time of 70 ms, and a fluorescent photon spectrum is constructed. This measurement is repeated by scanning the target sample, and finally a two-dimensional RGB-color image is obtained. The obtained image showed that the photons emitted from the dyes of mitochondria and cytoskeletons were clearly resolved at a detection intensity level of tens of photons. TES exhibits ideal performance as a photon detector with a low dark count rate (< 1 Hz) and wavelength resolving power. In the single-mode fiber-coupled system, the confocal microscope can be operated in the super-resolution mode. These features are very promising to realize high-sensitivity and high-resolution photon spectral imaging, and would help avoid cell damage and photobleaching of fluorescence dyes.

  18. Edge detection

    NASA Astrophysics Data System (ADS)

    Hildreth, E. C.

    1985-09-01

    For both biological systems and machines, vision begins with a large and unwieldly array of measurements of the amount of light reflected from surfaces in the environment. The goal of vision is to recover physical properties of objects in the scene such as the location of object boundaries and the structure, color and texture of object surfaces, from the two-dimensional image that is projected onto the eye or camera. This goal is not achieved in a single step: vision proceeds in stages, with each stage producing increasingly more useful descriptions of the image and then the scene. The first clues about the physical properties of the scene are provided by the changes of intensity in the image. The importance of intensity changes and edges in early visual processing has led to extensive research on their detection, description and use, both in computer and biological vision systems. This article reviews some of the theory that underlies the detection of edges, and the methods used to carry out this analysis.

  19. Soft x-ray absorption spectra of ilmenite family.

    PubMed

    Agui, A; Mizumaki, M; Saitoh, Y; Matsushita, T; Nakatani, T; Fukaya, A; Torikai, E

    2001-03-01

    We have carried out soft x-ray absorption spectroscopy to study the electronic structure of ilmenite family, such as MnTiO3, FeTiO3, and CoTiO3 at the soft x-ray beamline, BL23SU, at the SPring-8. The Ti and M L2,3 absorption spectra of MTiO3 (M=Mn, Fe, and Co) show spectra of Ti4+ and M2+ electron configurations, respectively. Except the Fe L2,3 spectrum, those spectra were understood within the O(h) symmetry around the transition metal ions. The Fe L3-edge spectrum clearly shows a doublet peak at the L3 edge, which is attributed to Fe2+ state, moreover the very high-resolution the L-edge spectra of transition metals show fine structures. The spectra of those ilmenites are compared.

  20. Operando Soft X-ray Absorption Spectroscopic Study on a Solid Oxide Fuel Cell Cathode during Electrochemical Oxygen Reduction.

    PubMed

    Nakamura, Takashi; Oike, Ryo; Kimura, Yuta; Tamenori, Yusuke; Kawada, Tatsuya; Amezawa, Koji

    2017-05-09

    An operando soft X-ray absorption spectroscopic technique, which enabled the analysis of the electronic structures of the electrode materials at elevated temperature in a controlled atmosphere and electrochemical polarization, was established and its availability was demonstrated by investigating the electronic structural changes of an La 2 NiO 4+δ dense-film electrode during an electrochemical oxygen reduction reaction. Clear O K-edge and Ni L-edge X-ray absorption spectra could be obtained below 773 K under an atmospheric pressure of 100 ppm O 2 /He, 0.1 % O 2 /He, and 1 % O 2 /He gas mixtures. Considerable spectral changes were observed in the O K-edge X-ray absorption spectra upon changing the PO2 and application of electrical potential, whereas only small spectral changes were observed in Ni L-edge X-ray absorption spectra. A pre-edge peak of the O K-edge X-ray absorption spectra, which reflects the unoccupied partial density of states of Ni 3d-O 2p hybridization, increased or decreased with cathodic or anodic polarization, respectively. The electronic structural changes of the outermost orbital of the electrode material due to electrochemical polarization were successfully confirmed by the operando X-ray absorption spectroscopic technique developed in this study. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. UV-Photochemistry of the Disulfide Bond: Evolution of Early Photoproducts from Picosecond X-ray Absorption Spectroscopy at the Sulfur K-Edge.

    PubMed

    Ochmann, Miguel; Hussain, Abid; von Ahnen, Inga; Cordones, Amy A; Hong, Kiryong; Lee, Jae Hyuk; Ma, Rory; Adamczyk, Katrin; Kim, Tae Kyu; Schoenlein, Robert W; Vendrell, Oriol; Huse, Nils

    2018-05-30

    We have investigated dimethyl disulfide as the basic moiety for understanding the photochemistry of disulfide bonds, which are central to a broad range of biochemical processes. Picosecond time-resolved X-ray absorption spectroscopy at the sulfur K-edge provides unique element-specific insight into the photochemistry of the disulfide bond initiated by 267 nm femtosecond pulses. We observe a broad but distinct transient induced absorption spectrum which recovers on at least two time scales in the nanosecond range. We employed RASSCF electronic structure calculations to simulate the sulfur-1s transitions of multiple possible chemical species, and identified the methylthiyl and methylperthiyl radicals as the primary reaction products. In addition, we identify disulfur and the CH 2 S thione as the secondary reaction products of the perthiyl radical that are most likely to explain the observed spectral and kinetic signatures of our experiment. Our study underscores the importance of elemental specificity and the potential of time-resolved X-ray spectroscopy to identify short-lived reaction products in complex reaction schemes that underlie the rich photochemistry of disulfide systems.

  2. Volcanic resurfacing of Io: Post-repair HST imaging

    USGS Publications Warehouse

    Spencer, J.R.; McEwen, A.S.; McGrath, M.A.; Sartoretti, P.; Nash, D.B.; Noll, K.S.; Gilmore, D.

    1997-01-01

    In March 1994, we used the newly refurbished Hubble Space Telescope (HST) to obtain global imaging of Io at five wavelengths between 0.34 and 1.02 ??m, with a spatial resolution of 160 km. The images provided the clearest view of Io since Voyager and the first systematic observations in the wavelength range 0.7-1.0 ??m. We have produced absolutely calibrated global mosaics of Io's reflectance in all our five wavelengths. The near-infrared images reveal that the 0.55-to 0.7-??m absorption edge seen in Io's disk-integrated spectrum has a very different spatial distribution from the better-known 0.40-to 0.50-??m absorption edge studied by Voyager, and must be generated by a different chemical species. The 0.55-to 0.7-??m absorption edge is strongly concentrated in the pyroclastic ejecta blanket of the volcano Pele, at a few much smaller discrete spots, and probably also in the polar regions. The Pele ejecta spectrum is consistent with the idea that S2O, partially decomposed to S4 (and probably S3), may be the species responsible for the 0.55-to 0.7-??m absorption edge at Pele and elsewhere on Io, though S4 generated by other processes may also be a possibility. S2O can be produced by high-temperature decomposition of SO2 gas, and the high temperature of the Pele volcano may account for its concentration there. Spectral anomalies of comparable size and prominence are not seen around the other "Pele-type" volcanos Surt and Aten (A. S. McEwen and L. A. Soderblom, 1983, Icarus 55, 191-217), suggesting that these volcanos, if chemically similar to Pele, are much less active. The spectrum of high-latitude regions is similar to that of quenched red sulfur glass, and if this similarity is not coincidental, the glass may be preserved here by the low polar surface temperatures. Alternatively, the low polar temperatures may preserve sulfur that has been reddened by radiation. There are many changes in albedo patterns in the 15 years between Voyager and these HST observations

  3. Volcanic Resurfacing of Io: Post-Repair HST Imaging

    NASA Astrophysics Data System (ADS)

    Spencer, John R.; McEwen, Alfred S.; McGrath, Melissa A.; Sartoretti, Paola; Nash, Douglas B.; Noll, Keith S.; Gilmore, Diane

    1997-05-01

    In March 1994, we used the newly refurbished Hubble Space Telescope (HST) to obtain global imaging of Io at five wavelengths between 0.34 and 1.02 μm, with a spatial resolution of 160 km. The images provided the clearest view of Io since Voyager and the first systematic observations in the wavelength range 0.7-1.0 μm. We have produced absolutely calibrated global mosaics of Io's reflectance in all our five wavelengths. The near-infrared images reveal that the 0.55- to 0.7-μm absorption edge seen in Io's disk-integrated spectrum has a very different spatial distribution from the better-known 0.40- to 0.50-μm absorption edge studied by Voyager, and must be generated by a different chemical species. The 0.55- to 0.7-μm absorption edge is strongly concentrated in the pyroclastic ejecta blanket of the volcano Pele, at a few much smaller discrete spots, and probably also in the polar regions. The Pele ejecta spectrum is consistent with the idea that S 2O, partially decomposed to S 4(and probably S 3), may be the species responsible for the 0.55- to 0.7-μm absorption edge at Pele and elsewhere on Io, though S 4generated by other processes may also be a possibility. S 2O can be produced by high-temperature decomposition of SO 2gas, and the high temperature of the Pele volcano may account for its concentration there. Spectral anomalies of comparable size and prominence are not seen around the other "Pele-type" volcanos Surt and Aten (A. S. McEwen and L. A. Soderblom, 1983, Icarus55, 191-217), suggesting that these volcanos, if chemically similar to Pele, are much less active. The spectrum of high-latitude regions is similar to that of quenched red sulfur glass, and if this similarity is not coincidental, the glass may be preserved here by the low polar surface temperatures. Alternatively, the low polar temperatures may preserve sulfur that has been reddened by radiation. There are many changes in albedo patterns in the 15 years between Voyager and these HST

  4. Localization of tumors in various organs, using edge detection algorithms

    NASA Astrophysics Data System (ADS)

    López Vélez, Felipe

    2015-09-01

    The edge of an image is a set of points organized in a curved line, where in each of these points the brightness of the image changes abruptly, or has discontinuities, in order to find these edges there will be five different mathematical methods to be used and later on compared with its peers, this is with the aim of finding which of the methods is the one that can find the edges of any given image. In this paper these five methods will be used for medical purposes in order to find which one is capable of finding the edges of a scanned image more accurately than the others. The problem consists in analyzing the following two biomedicals images. One of them represents a brain tumor and the other one a liver tumor. These images will be analyzed with the help of the five methods described and the results will be compared in order to determine the best method to be used. It was decided to use different algorithms of edge detection in order to obtain the results shown below; Bessel algorithm, Morse algorithm, Hermite algorithm, Weibull algorithm and Sobel algorithm. After analyzing the appliance of each of the methods to both images it's impossible to determine the most accurate method for tumor detection due to the fact that in each case the best method changed, i.e., for the brain tumor image it can be noticed that the Morse method was the best at finding the edges of the image but for the liver tumor image it was the Hermite method. Making further observations it is found that Hermite and Morse have for these two cases the lowest standard deviations, concluding that these two are the most accurate method to find the edges in analysis of biomedical images.

  5. Investigating the interstellar dust through the Fe K-edge

    NASA Astrophysics Data System (ADS)

    Rogantini, D.; Costantini, E.; Zeegers, S. T.; de Vries, C. P.; Bras, W.; de Groot, F.; Mutschke, H.; Waters, L. B. F. M.

    2018-01-01

    Context. The chemical and physical properties of interstellar dust in the densest regions of the Galaxy are still not well understood. X-rays provide a powerful probe since they can penetrate gas and dust over a wide range of column densities (up to 1024 cm-2). The interaction (scattering and absorption) with the medium imprints spectral signatures that reflect the individual atoms which constitute the gas, molecule, or solid. Aims: In this work we investigate the ability of high resolution X-ray spectroscopy to probe the properties of cosmic grains containing iron. Although iron is heavily depleted into interstellar dust, the nature of the Fe-bearing grains is still largely uncertain. Methods: In our analysis we use iron K-edge synchrotron data of minerals likely present in the ISM dust taken at the European Synchrotron Radiation Facility. We explore the prospects of determining the chemical composition and the size of astrophysical dust in the Galactic centre and in molecular clouds with future X-ray missions. The energy resolution and the effective area of the present X-ray telescopes are not sufficient to detect and study the Fe K-edge, even for bright X-ray sources. Results: From the analysis of the extinction cross sections of our dust models implemented in the spectral fitting program SPEX, the Fe K-edge is promising for investigating both the chemistry and the size distribution of the interstellar dust. We find that the chemical composition regulates the X-ray absorption fine structures in the post edge region, whereas the scattering feature in the pre-edge is sensitive to the mean grain size. Finally, we note that the Fe K-edge is insensitive to other dust properties, such as the porosity and the geometry of the dust. The absorption, scattering, and extinction cross sections of the compounds are 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/609/A22

  6. X-ray-induced debromination of nucleic acids at the Br K absorption edge and implications for MAD phasing.

    PubMed

    Ennifar, E; Carpentier, P; Ferrer, J L; Walter, P; Dumas, P

    2002-08-01

    Multi-wavelength anomalous dispersion (MAD) using brominated derivatives is considered a common and convenient technique for solving chemically synthesized nucleic acid structures. Here, it is shown that a relatively moderate X-ray dose (of the order of 5 x 10(15) photons mm(-2)) can induce sufficient debromination to prevent structure determination. The decrease in bromine occupancy with radiation dose can be accounted for by a simple exponential, with an estimated rate constant at the absorption-peak wavelength, 7.4 (0.8) MGy, that is not significantly different from its value at the absorption-edge wavelength, 9.2 (2.6) MGy (the given e.s.d.s assess the relative closeness of the two values, not their absolute accuracy, which is probably worse). Chemically, these results (and others) are consistent with bromine cleavage resulting from direct photodissociation and/or from the action of free electrons, rather than from the action of hydroxyl radicals originating from water dissociation. The free bromine species (Br(-)) diffuse too quickly, even in amorphous ice around 100 K, to allow the determination of a diffusion coefficient. From a practical point of view, it is suggested that a single data collection with a crystal consisting of iodinated instead of brominated derivatives could provide both anomalous scattering and SIR phase information by the progressive cleavage of iodine.

  7. Edge Response and NIIRS Estimates for Commercial Remote Sensing Satellites

    NASA Technical Reports Server (NTRS)

    Blonski, Slawomir; Ryan, Robert E.; Pagnutti, mary; Stanley, Thomas

    2006-01-01

    Spatial resolution of panchromatic imagery from commercial remote sensing satellites was characterized based on edge response measurements using edge targets and the tilted-edge technique. Relative Edge Response (RER) was estimated as a geometric mean of normalized edge response differences measured in two directions of image pixels at points distanced from the edge by -0.5 and 0.5 of ground sample distance. RER is one of the engineering parameters used in the General Image Quality Equation to provide predictions of imaging system performance expressed in terms of the National Imagery Interpretability Rating Scale (NIIRS). By assuming a plausible range of signal-to-noise ratio and assessing the effects of Modulation Transfer Function compensation, the NIIRS estimates were made and then compared with vendor-provided values and evaluations conducted by the National Geospatial-Intelligence Agency.

  8. Ultrafast X-Ray Absorption Spectroscopy of Isochorically Heated Warm Dense Matter

    NASA Astrophysics Data System (ADS)

    Engelhorn, Kyle Craig

    This dissertation will present a series of new tools, together with new techniques, focused on the understanding of warm and dense matter. We report on the development of a high time resolution and high detection efficiency x-ray camera. The camera is integrated with a short pulse laser and an x-ray beamline at the Advanced Light Source synchrotron. This provides an instrument for single shot, broadband x-ray absorption spectroscopy of warm and dense matter with 2 picosecond time resolution. Warm and dense matter is created by isochorically heating samples of known density with an ultrafast optical laser pulse, and X-ray absorption spectroscopy probes the unoccupied electronic density of states before the onset of hydrodynamic expansion and electron-ion equilibrium is reached. Measured spectra from a variety of materials are compared with first principle molecular dynamics and density functional theory calculations. In heated silicon dioxide spectra, two novel pre-edge features are observed, a peak below the band gap and absorption within the band gap, while a reduction was observed in the features above the edge. From consideration of the calculated spectra, the peak below the gap is attributed to valence electrons that have been promoted to the conduction band, the absorption within the gap is attributed to broken Si-O bonds, and the reduction above the edge is attributed to an elevated ionic temperature. In heated copper spectra, a time-dependent shift and broadening of the absorption edge are observed, consistent with and elevated electron temperature. The temporal evolution of the electronic temperature is accurately determined by fitting the measured spectra with calculated spectra. The electron-ion equilibration is studied with a two-temperature model. In heated nickel spectra, a shift of the absorption edge is observed. This shift is found to be inconsistent with calculated spectra and independent of incident laser fluence. A shift of the chemical potential

  9. Electronic structure of nickel silicide in subhalf-micron lines and blanket films: An x-ray absorption fine structures study at the Ni and Si L3,2 edge

    NASA Astrophysics Data System (ADS)

    Naftel, S. J.; Coulthard, I.; Sham, T. K.; Xu, D.-X.; Erickson, L.; Das, S. R.

    1999-05-01

    We report a Ni and Si L3,2-edge x-ray absorption near edge structures (XANES) study of nickel-silicon interaction in submicron (0.15 and 0.2 μm) lines on a n-Si(100) wafer as well as a series of well characterized Ni-Si blanket films. XANES measurements recorded in both total electron yield and soft x-ray fluorescence yield indicate that under the selected silicidation conditions, the more desirable low resistivity phase, NiSi, is indeed the dominant phase in the subhalf-micron lines although the formation of this phase is less complete as the line becomes narrower and this is accompanied by a Ni rich surface.

  10. Understanding refraction contrast using a comparison of absorption and refraction computed tomographic techniques

    NASA Astrophysics Data System (ADS)

    Wiebe, S.; Rhoades, G.; Wei, Z.; Rosenberg, A.; Belev, G.; Chapman, D.

    2013-05-01

    Refraction x-ray contrast is an imaging modality used primarily in a research setting at synchrotron facilities, which have a biomedical imaging research program. The most common method for exploiting refraction contrast is by using a technique called Diffraction Enhanced Imaging (DEI). The DEI apparatus allows the detection of refraction between two materials and produces a unique ''edge enhanced'' contrast appearance, very different from the traditional absorption x-ray imaging used in clinical radiology. In this paper we aim to explain the features of x-ray refraction contrast as a typical clinical radiologist would understand. Then a discussion regarding what needs to be considered in the interpretation of the refraction image takes place. Finally we present a discussion about the limitations of planar refraction imaging and the potential of DEI Computed Tomography. This is an original work that has not been submitted to any other source for publication. The authors have no commercial interests or conflicts of interest to disclose.

  11. Defect-induced band-edge reconstruction of a bismuth-halide double perovskite for visible-light absorption

    DOE PAGES

    Slavney, Adam H.; Leppert, Linn; Bartesaghi, Davide; ...

    2017-03-29

    In this study, halide double perovskites have recently been developed as less toxic analogs of the lead perovskite solar-cell absorbers APbX 3 (A = monovalent cation; X = Br or I). However, all known halide double perovskites have large bandgaps that afford weak visible-light absorption. The first halide double perovskite evaluated as an absorber, Cs 2AgBiBr 6 (1), has a bandgap of 1.95 eV. Here, we show that dilute alloying decreases 1’s bandgap by ca. 0.5 eV. Importantly, time-resolved photoconductivity measurements reveal long-lived carriers with microsecond lifetimes in the alloyed material, which is very promising for photovoltaic applications. The alloyedmore » perovskite described herein is the first double perovskite to show comparable bandgap energy and carrier lifetime to those of (CH 3NH 3)PbI 3. By describing how energy- and symmetry-matched impurity orbitals, at low concentrations, dramatically alter 1’s band edges, we open a potential pathway for the large and diverse family of halide double perovskites to compete with APbX 3 absorbers.« less

  12. Simulating Ru L 3 -Edge X-ray Absorption Spectroscopy with Time-Dependent Density Functional Theory: Model Complexes and Electron Localization in Mixed-Valence Metal Dimers

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Van Kuiken, Benjamin E.; Valiev, Marat; Daifuku, Stephanie L.

    2013-05-30

    Ruthenium L3-edge X-ray absorption (XA) spectroscopy probes unoccupied 4d orbitals of the metal atom and is increasingly being used to investigate the local electronic structure in ground and excited electronic states of Ru complexes. The simultaneous development of computational tools for simulating Ru L3-edge spectra is crucial for interpreting the spectral features at a molecular level. This study demonstrates that time-dependent density functional theory (TDDFT) is a viable and predictive tool for simulating ruthenium L3-edge XA spectroscopy. We systematically investigate the effects of exchange correlation functional and implicit and explicit solvent interactions on a series of RuII and RuIII complexesmore » in their ground and electronic excited states. The TDDFT simulations reproduce all of the experimentally observed features in Ru L3-edge XA spectra within the experimental resolution (0.4 eV). Our simulations identify ligand-specific charge transfer features in complicated Ru L3-edge spectra of [Ru(CN)6]4- and RuII polypyridyl complexes illustrating the advantage of using TDDFT in complex systems. We conclude that the B3LYP functional most accurately predicts the transition energies of charge transfer features in these systems. We use our TDDFT approach to simulate experimental Ru L3-edge XA spectra of transition metal mixed-valence dimers of the form [(NC)5MII-CN-RuIII(NH3)5] (where M = Fe or Ru) dissolved in water. Our study determines the spectral signatures of electron delocalization in Ru L3-edge XA spectra. We find that the inclusion of explicit solvent molecules is necessary for reproducing the spectral features and the experimentally determined valencies in these mixed-valence complexes. This study validates the use of TDDFT for simulating Ru 2p excitations using popular quantum chemistry codes and providing a powerful interpretive tool for equilibrium and ultrafast Ru L3-edge XA spectroscopy.« less

  13. Simulating Ru L3-edge X-ray Absorption Spectroscopy with Time-Dependent Density Functional Theory: Model Complexes and Electron Localization in Mixed-Valence Metal Dimers

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Van Kuiken, Benjamin E.; Valiev, Marat; Daifuku, Stephanie L.

    2013-05-01

    Ruthenium L2,3-edge X-ray absorption (XA) spectroscopy probes transitions from core 2p orbitals to the 4d levels of the atom and is a powerful tool for interrogating the local electronic and molecular structure around the metal atom. However, a molecular-level interpretation of the Ru L2,3-edge spectral lineshapes is often complicated by spin–orbit coupling (SOC) and multiplet effects. In this study, we develop spin-free time-dependent density functional theory (TDDFT) as a viable and predictive tool to simulate the Ru L3-edge spectra. We successfully simulate and analyze the ground state Ru L3-edge XA spectra of a series of RuII and RuIII complexes: [Ru(NH3)6]2+/3+,more » [Ru(CN)6]4-/3-, [RuCl6]4-/3-, and the ground (1A1) and photoexcited (3MLCT) transient states of [Ru(bpy)3]2+ and Ru(dcbpy)2(NCS)2 (termed N3). The TDDFT simulations reproduce all the experimentally observed features in Ru L3-edge XA spectra. The advantage of using TDDFT to assign complicated Ru L3-edge spectra is illustrated by its ability to identify ligand specific charge transfer features in complex molecules. We conclude that the B3LYP functional is the most reliable functional for accurately predicting the location of charge transfer features in these spectra. Experimental and simulated Ru L3-edge XA spectra are presented for the transition metal mixed-valence dimers [(NC)5MII-CN-RuIII(NH3)5]- (where M = Fe or Ru) dissolved in water. We explore the spectral signatures of electron delocalization in Ru L3-edge XA spectroscopy and our simulations reveal that the inclusion of explicit solvent molecules is crucial for reproducing the experimentally determined valencies, highlighting the importance of the role of the solvent in transition metal charge transfer chemistry.« less

  14. Three-dimensional profile extraction from CD-SEM image and top/bottom CD measurement by line-edge roughness analysis

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Atsuko; Ohashi, Takeyoshi; Kawasaki, Takahiro; Inoue, Osamu; Kawada, Hiroki

    2013-04-01

    A new method for calculating critical dimension (CDs) at the top and bottom of three-dimensional (3D) pattern profiles from a critical-dimension scanning electron microscope (CD-SEM) image, called as "T-sigma method", is proposed and evaluated. Without preparing a library of database in advance, T-sigma can estimate a feature of a pattern sidewall. Furthermore, it supplies the optimum edge-definition (i.e., threshold level for determining edge position from a CDSEM signal) to detect the top and bottom of the pattern. This method consists of three steps. First, two components of line-edge roughness (LER); noise-induced bias (i.e., LER bias) and unbiased component (i.e., bias-free LER) are calculated with set threshold level. Second, these components are calculated with various threshold values, and the threshold-dependence of these two components, "T-sigma graph", is obtained. Finally, the optimum threshold value for the top and the bottom edge detection are given by the analysis of T-sigma graph. T-sigma was applied to CD-SEM images of three kinds of resist-pattern samples. In addition, reference metrology was performed with atomic force microscope (AFM) and scanning transmission electron microscope (STEM). Sensitivity of CD measured by T-sigma to the reference CD was higher than or equal to that measured by the conventional edge definition. Regarding the absolute measurement accuracy, T-sigma showed better results than the conventional definition. Furthermore, T-sigma graphs were calculated from CD-SEM images of two kinds of resist samples and compared with corresponding STEM observation results. Both bias-free LER and LER bias increased as the detected edge point moved from the bottom to the top of the pattern in the case that the pattern had a straight sidewall and a round top. On the other hand, they were almost constant in the case that the pattern had a re-entrant profile. T-sigma will be able to reveal a re-entrant feature. From these results, it is found

  15. Specimen preparation, imaging, and analysis protocols for knife-edge scanning microscopy.

    PubMed

    Choe, Yoonsuck; Mayerich, David; Kwon, Jaerock; Miller, Daniel E; Sung, Chul; Chung, Ji Ryang; Huffman, Todd; Keyser, John; Abbott, Louise C

    2011-12-09

    Major advances in high-throughput, high-resolution, 3D microscopy techniques have enabled the acquisition of large volumes of neuroanatomical data at submicrometer resolution. One of the first such instruments producing whole-brain-scale data is the Knife-Edge Scanning Microscope (KESM), developed and hosted in the authors' lab. KESM has been used to section and image whole mouse brains at submicrometer resolution, revealing the intricate details of the neuronal networks (Golgi), vascular networks (India ink), and cell body distribution (Nissl). The use of KESM is not restricted to the mouse nor the brain. We have successfully imaged the octopus brain, mouse lung, and rat brain. We are currently working on whole zebra fish embryos. Data like these can greatly contribute to connectomics research; to microcirculation and hemodynamic research; and to stereology research by providing an exact ground-truth. In this article, we will describe the pipeline, including specimen preparation (fixing, staining, and embedding), KESM configuration and setup, sectioning and imaging with the KESM, image processing, data preparation, and data visualization and analysis. The emphasis will be on specimen preparation and visualization/analysis of obtained KESM data. We expect the detailed protocol presented in this article to help broaden the access to KESM and increase its utilization.

  16. Spectral K-edge subtraction imaging of experimental non-radioactive barium uptake in bone.

    PubMed

    Panahifar, Arash; Samadi, Nazanin; Swanston, Treena M; Chapman, L Dean; Cooper, David M L

    2016-12-01

    To evaluate the feasibility of using non-radioactive barium as a bone tracer for detection with synchrotron spectral K-edge subtraction (SKES) technique. Male rats of 1-month old (i.e., developing skeleton) and 8-month old (i.e., skeletally mature) were orally dosed with low dose of barium chloride (33mg/kg/day Ba 2+ ) for 4weeks. The fore and hind limbs were dissected for imaging in projection and computed tomography modes at 100μm and 52μm pixel sizes. The SKES method utilizes a single bent Laue monochromator to prepare a 550eV energy spectrum to encompass the K-edge of barium (37.441keV), for collecting both 'above' and 'below' the K-edge data sets in a single scan. The SKES has a very good focal size, thus limits the 'crossover' and motion artifacts. In juvenile rats, barium was mostly incorporated in the areas of high bone turnover such as at the growth plate and the trabecular surfaces, but also in the cortical bone as the animals were growing at the time of tracer administration. However, the adults incorporated approximately half the concentration and mainly in the areas where bone remodeling was predominant and occasionally in the periosteal and endosteal layers of the diaphyseal cortical bone. The presented methodology is simple to implement and provides both structural and functional information, after labeling with barium, on bone micro-architecture and thus has great potential for in vivo imaging of pre-clinical animal models of musculoskeletal diseases to better understand their mechanisms and to evaluate the efficacy of pharmaceuticals. Copyright © 2016 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  17. Edge Density Imaging: Mapping the Anatomic Embedding of the Structural Connectome Within the White Matter of the Human Brain

    PubMed Central

    Owen, Julia P.; Chang, Yi-Shin; Mukherjee, Pratik

    2015-01-01

    The structural connectome has emerged as a powerful tool to characterize the network architecture of the human brain and shows great potential for generating important new biomarkers for neurologic and psychiatric disorders. The edges of the cerebral graph traverse white matter to interconnect cortical and subcortical nodes, although the anatomic embedding of these edges is generally overlooked in the literature. Mapping the paths of the connectome edges could elucidate the relative importance of individual white matter tracts to the overall network topology of the brain and also lead to a better understanding of the effect of regionally-specific white matter pathology on cognition and behavior. In this work, we introduce edge density imaging (EDI), which maps the number of network edges that pass through every white matter voxel. Test-retest analysis shows good to excellent reliability for edge density (ED) measurements, with consistent results using different cortical and subcortical parcellation schemes and different diffusion MR imaging acquisition parameters. We also demonstrate that ED yields complementary information to both traditional and emerging voxel-wise metrics of white matter microstructure and connectivity, including fractional anisotropy, track density, fiber orientation dispersion and neurite density. Our results demonstrate spatially ordered variations of ED throughout the white matter, notably including greater ED in posterior than anterior cerebral white matter. The EDI framework is employed to map the white matter regions that are enriched with pathways connecting rich club nodes and also those with high densities of intra-modular and inter-modular edges. We show that periventricular white matter has particularly high ED and high densities of rich club edges, which is significant for diseases in which these areas are selectively affected, ranging from white matter injury of prematurity in infants to leukoaraiosis in the elderly. Using edge

  18. Experimental determination of single CdSe nanowire absorption cross sections through photothermal imaging.

    PubMed

    Giblin, Jay; Syed, Muhammad; Banning, Michael T; Kuno, Masaru; Hartland, Greg

    2010-01-26

    Absorption cross sections ((sigma)abs) of single branched CdSe nanowires (NWs) have been measured by photothermal heterodyne imaging (PHI). Specifically, PHI signals from isolated gold nanoparticles (NPs) with known cross sections were compared to those of individual CdSe NWs excited at 532 nm. This allowed us to determine average NW absorption cross sections at 532 nm of (sigma)abs = (3.17 +/- 0.44) x 10(-11) cm2/microm (standard error reported). This agrees well with a theoretical value obtained using a classical electromagnetic analysis ((sigma)abs = 5.00 x 10(-11) cm2/microm) and also with prior ensemble estimates. Furthermore, NWs exhibit significant absorption polarization sensitivities consistent with prior NW excitation polarization anisotropy measurements. This has enabled additional estimates of the absorption cross section parallel ((sigma)abs) and perpendicular ((sigma)abs(perpendicular) to the NW growth axis, as well as the corresponding NW absorption anisotropy ((rho)abs). Resulting values of (sigma)abs = (5.6 +/- 1.1) x 10(-11) cm2/microm, (sigma)abs(perpendicular) = (1.26 +/- 0.21) x 10(-11) cm2/microm, and (rho)abs = 0.63+/- 0.04 (standard errors reported) are again in good agreement with theoretical predictions. These measurements all indicate sizable NW absorption cross sections and ultimately suggest the possibility of future direct single NW absorption studies.

  19. Edge Modeling by Two Blur Parameters in Varying Contrasts.

    PubMed

    Seo, Suyoung

    2018-06-01

    This paper presents a method of modeling edge profiles with two blur parameters, and estimating and predicting those edge parameters with varying brightness combinations and camera-to-object distances (COD). First, the validity of the edge model is proven mathematically. Then, it is proven experimentally with edges from a set of images captured for specifically designed target sheets and with edges from natural images. Estimation of the two blur parameters for each observed edge profile is performed with a brute-force method to find parameters that produce global minimum errors. Then, using the estimated blur parameters, actual blur parameters of edges with arbitrary brightness combinations are predicted using a surface interpolation method (i.e., kriging). The predicted surfaces show that the two blur parameters of the proposed edge model depend on both dark-side edge brightness and light-side edge brightness following a certain global trend. This is similar across varying CODs. The proposed edge model is compared with a one-blur parameter edge model using experiments of the root mean squared error for fitting the edge models to each observed edge profile. The comparison results suggest that the proposed edge model has superiority over the one-blur parameter edge model in most cases where edges have varying brightness combinations.

  20. Minerals discovered in paleolithic black pigments by transmission electron microscopy and micro-X-ray absorption near-edge structure

    NASA Astrophysics Data System (ADS)

    Chalmin, E.; Vignaud, C.; Salomon, H.; Farges, F.; Susini, J.; Menu, M.

    2006-05-01

    Analysis of archeological materials aims to rediscover the know-how of prehistoric men by determining the nature of the painting matter, its preparation mode, and the geographic origin of its raw materials. The preparation mode of the painting matter of the paleolithic rock art apparently consisted of mixing, grinding, and also heat-treatment. In this study, we focus on black pigments and more particularly manganese oxides. Using the combined approach of transmission electron microscopy (TEM) and Mn K-edge X-ray absorption near-edge structure (XANES) spectroscopy, we analyzed a variety of archeological black painted samples. The studied pigments arise from the caves of Ekain (Basque country, Spain), Labastide and Gargas (Hautes-Pyrénées, France). In addition, a black “crayon” (i.e., a “pen”) from the cave of Combe Saunière (Dordogne, France) was also investigated. From the analysis of these painting matters, several unusual minerals have been identified as black pigment, such as manganite, groutite, todorokite and birnessite. These conclusions enable us to estimate the technical level of paleolithic artists: they didn’t use heat-treatment to prepare black painting matter. Consequently, the unusual mineralogy found in some of these pigments suggests that some of the manganese ores are coming from geological settings that are sometimes relatively far away from the Dordogne and Basque region such as in Ariège (central-oriental Pyrénées).

  1. Laboratory implementation of edge illumination X-ray phase-contrast imaging with energy-resolved detectors

    NASA Astrophysics Data System (ADS)

    Diemoz, P. C.; Endrizzi, M.; Vittoria, F. A.; Hagen, C. K.; Kallon, G.; Basta, D.; Marenzana, M.; Delogu, P.; Vincenzi, A.; De Ruvo, L.; Spandre, G.; Brez, A.; Bellazzini, R.; Olivo, A.

    2015-03-01

    Edge illumination (EI) X-ray phase-contrast imaging (XPCI) has potential for applications in different fields of research, including materials science, non-destructive industrial testing, small-animal imaging, and medical imaging. One of its main advantages is the compatibility with laboratory equipment, in particular with conventional non-microfocal sources, which makes its exploitation in normal research laboratories possible. In this work, we demonstrate that the signal in laboratory implementations of EI can be correctly described with the use of the simplified geometrical optics. Besides enabling the derivation of simple expressions for the sensitivity and spatial resolution of a given EI setup, this model also highlights the EI's achromaticity. With the aim of improving image quality, as well as to take advantage of the fact that all energies in the spectrum contribute to the image contrast, we carried out EI acquisitions using a photon-counting energy-resolved detector. The obtained results demonstrate that this approach has great potential for future laboratory implementations of EI.

  2. Non-destructive studies of fuel pellets by neutron resonance absorption radiography and thermal neutron radiography

    NASA Astrophysics Data System (ADS)

    Tremsin, A. S.; Vogel, S. C.; Mocko, M.; Bourke, M. A. M.; Yuan, V.; Nelson, R. O.; Brown, D. W.; Feller, W. B.

    2013-09-01

    Many isotopes in nuclear materials exhibit strong peaks in neutron absorption cross sections in the epithermal energy range (1-1000 eV). These peaks (often referred to as resonances) occur at energies specific to particular isotopes, providing a means of isotope identification and concentration measurements. The high penetration of epithermal neutrons through most materials is very useful for studies where samples consist of heavy-Z elements opaque to X-rays and sometimes to thermal neutrons as well. The characterization of nuclear fuel elements in their cladding can benefit from the development of high resolution neutron resonance absorption imaging (NRAI), enabled by recently developed spatially-resolved neutron time-of-flight detectors. In this technique the neutron transmission of the sample is measured as a function of spatial location and of neutron energy. In the region of the spectra that borders the resonance energy for a particular isotope, the reduction in transmission can be used to acquire an image revealing the 2-dimensional distribution of that isotope within the sample. Provided that the energy of each transmitted neutron is measured by the neutron detector used and the irradiated sample possesses neutron absorption resonances, then isotope-specific location maps can be acquired simultaneously for several isotopes. This can be done even in the case where samples are opaque or have very similar transmission for thermal neutrons and X-rays or where only low concentrations of particular isotopes are present (<0.1 atom% in some cases). Ultimately, such radiographs of isotope location can be utilized to measure isotope concentration, and can even be combined to produce three-dimensional distributions using tomographic methods. In this paper we present the proof-of-principle of NRAI and transmission Bragg edge imaging performed at Flight Path 5 (FP5) at the LANSCE pulsed, moderated neutron source of Los Alamos National Laboratory. A set of urania mockup

  3. Optical absorption in degenerately doped semiconductors: Mott transition or Mahan excitons?

    NASA Astrophysics Data System (ADS)

    Schleife, André.; Rödl, Claudia; Hannewald, Karsten; Bechstedt, Friedhelm

    2012-02-01

    In the exploration of material properties, parameter-free calculations are a modern, sophisticated complement to cutting-edge experimental techniques. Ab-initio calculations are now capable of providing a deep understanding of the interesting physics underlying the electronic structure and optical absorption, e.g., of the transparent conductive oxides. Due to electron doping, these materials are conductive even though they have wide fundamental band gaps. The degenerate electron gas in the lowest conduction-band states drastically modifies the Coulomb interaction between the electrons and, hence, the optical properties close to the absorption edge. We describe these effects by developing an ab-initio technique which captures also the Pauli blocking and the Fermi-edge singularity at the optical absorption onset, that occur in addition to quasiparticle and excitonic effects. We answer the question whether free carriers induce an excitonic Mott transition or trigger the evolution of Wannier-Mott excitons into Mahan excitons. The prototypical n-type zinc oxide is studied as an example.

  4. Photochemically Generated Thiyl Free Radicals Observed by X-ray Absorption Spectroscopy

    DOE PAGES

    Sneeden, Eileen Y.; Hackett, Mark J.; Cotelesage, Julien J. H.; ...

    2017-07-27

    Sulfur-based thiyl radicals are known to be involved in a wide range of chemical and biological processes, but they are often highly reactive, which makes them difficult to observe directly. We report herein X-ray absorption spectra and analysis that support the direct observation of two different thiyl species generated photochemically by X-ray irradiation. The thiyl radical sulfur K-edge X-ray absorption spectra of both species are characterized by a uniquely low energy transition at about 2465 eV, which occurs at a lower energy than any previously observed feature at the sulfur K-edge and corresponds to a 1s → 3p transition tomore » the singly occupied molecular orbital of the free radical. In conclusion, our results constitute the first observation of substantial levels of thiyl radicals generated by X-ray irradiation and detected by sulfur K-edge X-ray absorption spectroscopy.« less

  5. CMOS image sensor with organic photoconductive layer having narrow absorption band and proposal of stack type solid-state image sensors

    NASA Astrophysics Data System (ADS)

    Takada, Shunji; Ihama, Mikio; Inuiya, Masafumi

    2006-02-01

    Digital still cameras overtook film cameras in Japanese market in 2000 in terms of sales volume owing to their versatile functions. However, the image-capturing capabilities such as sensitivity and latitude of color films are still superior to those of digital image sensors. In this paper, we attribute the cause for the high performance of color films to their multi-layered structure, and propose the solid-state image sensors with stacked organic photoconductive layers having narrow absorption bands on CMOS read-out circuits.

  6. Low Dose CT Reconstruction via Edge-preserving Total Variation Regularization

    PubMed Central

    Tian, Zhen; Jia, Xun; Yuan, Kehong; Pan, Tinsu; Jiang, Steve B.

    2014-01-01

    High radiation dose in CT scans increases a lifetime risk of cancer and has become a major clinical concern. Recently, iterative reconstruction algorithms with Total Variation (TV) regularization have been developed to reconstruct CT images from highly undersampled data acquired at low mAs levels in order to reduce the imaging dose. Nonetheless, the low contrast structures tend to be smoothed out by the TV regularization, posing a great challenge for the TV method. To solve this problem, in this work we develop an iterative CT reconstruction algorithm with edge-preserving TV regularization to reconstruct CT images from highly undersampled data obtained at low mAs levels. The CT image is reconstructed by minimizing an energy consisting of an edge-preserving TV norm and a data fidelity term posed by the x-ray projections. The edge-preserving TV term is proposed to preferentially perform smoothing only on non-edge part of the image in order to better preserve the edges, which is realized by introducing a penalty weight to the original total variation norm. During the reconstruction process, the pixels at edges would be gradually identified and given small penalty weight. Our iterative algorithm is implemented on GPU to improve its speed. We test our reconstruction algorithm on a digital NCAT phantom, a physical chest phantom, and a Catphan phantom. Reconstruction results from a conventional FBP algorithm and a TV regularization method without edge preserving penalty are also presented for comparison purpose. The experimental results illustrate that both TV-based algorithm and our edge-preserving TV algorithm outperform the conventional FBP algorithm in suppressing the streaking artifacts and image noise under the low dose context. Our edge-preserving algorithm is superior to the TV-based algorithm in that it can preserve more information of low contrast structures and therefore maintain acceptable spatial resolution. PMID:21860076

  7. Fermi-Edge Singularity of Spin-Polarized Electrons

    NASA Astrophysics Data System (ADS)

    Plochocka-Polack, P.; Groshaus, J. G.; Rappaport, M.; Umansky, V.; Gallais, Y.; Pinczuk, A.; Bar-Joseph, I.

    2007-05-01

    We study the absorption spectrum of a two-dimensional electron gas (2DEG) in a magnetic field. We find that at low temperatures, when the 2DEG is spin polarized, the absorption spectra, which correspond to the creation of spin up or spin down electrons, differ in magnitude, linewidth, and filling factor dependence. We show that these differences can be explained as resulting from the creation of a Mahan exciton in one case, and of a power law Fermi-edge singularity in the other.

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

    PubMed Central

    Gultekin, David H.; Moeller, Lothar

    2013-01-01

    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 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. PMID:23248293

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

    PubMed

    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.

  10. Real-time and quantitative fluorescent live-cell imaging with quadruplex-specific red-edge probe (G4-REP).

    PubMed

    Yang, Sunny Y; Amor, Souheila; Laguerre, Aurélien; Wong, Judy M Y; Monchaud, David

    2017-05-01

    The development of quadruplex-directed molecular diagnostic and therapy rely on mechanistic insights gained at both cellular and tissue levels by fluorescence imaging. This technique is based on fluorescent reporters that label cellular DNA and RNA quadruplexes to spatiotemporally address their complex cell biology. The photophysical characteristics of quadruplex probes usually dictate the modality of cell imaging by governing the selection of the light source (lamp, LED, laser), the optical light filters and the detection modality. Here, we report the characterizations of prototype from a new generation of quadruplex dye termed G4-REP (for quadruplex-specific red-edge probe) that provides fluorescence responses regardless of the excitation wavelength and modality (owing to the versatility gained through the red-edge effect), thus allowing for diverse applications and most imaging facilities. This is demonstrated by cell images (and associated quantifications) collected through confocal and multiphoton microscopy as well as through real-time live-cell imaging system over extended period, monitoring both non-cancerous and cancerous human cell lines. Our results promote a new way of designing versatile, efficient and convenient quadruplex-reporting dyes for tracking these higher-order nucleic acid structures in living human cells. This article is part of a Special Issue entitled "G-quadruplex" Guest Editor: Dr. Concetta Giancola and Dr. Daniela Montesarchio. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Information theoretic analysis of edge detection in visual communication

    NASA Astrophysics Data System (ADS)

    Jiang, Bo; Rahman, Zia-ur

    2010-08-01

    Generally, the designs of digital image processing algorithms and image gathering devices remain separate. Consequently, the performance of digital image processing algorithms is evaluated without taking into account the artifacts introduced into the process by the image gathering process. However, experiments show that the image gathering process profoundly impacts the performance of digital image processing and the quality of the resulting images. Huck et al. proposed one definitive theoretic analysis of visual communication channels, where the different parts, such as image gathering, processing, and display, are assessed in an integrated manner using Shannon's information theory. In this paper, we perform an end-to-end information theory based system analysis to assess edge detection methods. We evaluate the performance of the different algorithms as a function of the characteristics of the scene, and the parameters, such as sampling, additive noise etc., that define the image gathering system. The edge detection algorithm is regarded to have high performance only if the information rate from the scene to the edge approaches the maximum possible. This goal can be achieved only by jointly optimizing all processes. People generally use subjective judgment to compare different edge detection methods. There is not a common tool that can be used to evaluate the performance of the different algorithms, and to give people a guide for selecting the best algorithm for a given system or scene. Our information-theoretic assessment becomes this new tool to which allows us to compare the different edge detection operators in a common environment.

  12. Edge effects in phase-shifting masks for 0.25-µm lithography

    NASA Astrophysics Data System (ADS)

    Wong, Alfred K. K.; Neureuther, Andrew R.

    1993-03-01

    The impact on image quality of scattering from phase-shifter edges and of interactions between phase-shifter and chrome edges is assessed using rigorous electromagnetic simulation. Effects of edge taper in phase-shift masks, spacing between phase-shifter and chrome edges, small outrigger features with a trench phase-shifter, and of the repair of phase defects by etching to 360 degree(s) are considered. Near field distributions and diffraction efficiencies are examined and images are compared with more approximate results from the commonly used Hopkins' theory of imaging.

  13. Electrosynthesis of ZnO nanorods and nanotowers: Morphology and X-ray Absorption Near Edge Spectroscopy studies

    NASA Astrophysics Data System (ADS)

    Sigircik, Gokmen; Erken, Ozge; Tuken, Tunc; Gumus, Cebrail; Ozkendir, Osman M.; Ufuktepe, Yuksel

    2015-06-01

    Deposition mechanism of nano-structured ZnO films has been investigated in the absence and presence of chloride ions from aqueous solution. The resulting opto-electronic properties were interpreted extensively, using X-ray diffraction (XRD), X-ray Absorption Near Edge Spectroscopy (XANES), field emission scanning electron microscopy (FE-SEM), UV-Visible spectroscopy and four probe techniques. The ZnO deposition is mass transport controlled process and the interaction of chloride ions with the surface has great influence on diffusion kinetics, considering the substantial species (Zn2+ and OH-) involved in the construction of ZnO film. This effect does not change major lattice parameters, as shown with detailed analysis of XRD data. However, the texture coefficient (Tc) (0 0 2) value is higher in presence of chloride ions containing synthesis solution which gave vertically aligned, well defined and uniformly dispersed nanorods structure. The calculated Eg values are in the range 3.28-3.41 eV and 3.22-3.31 eV for ZnO nanorods and nanotowers synthesized at different deposition periods, respectively. Furthermore, the charge mobility values regarding the deposition periods were measured to be in the ranges from 130.4 to 449.2 cm2 V-1 s-1 and 126.2 to 204.7 cm2 V-1 s-1 for nanorods and nanotowers, respectively. From XANES results, it was shown that the Zn K-edge spectrum is dominated by the transition of Zn 1s core electrons into the unoccupied Zn 4p states of the conduction band. Comparing the rod and tower nano-structured ZnO thin films, the excitation behavior of valence band electrons is different. Moreover, the density states of Zn 4p are higher for ZnO nanorods.

  14. L-edge spectroscopy of dilute, radiation-sensitive systems using a transition-edge-sensor array

    NASA Astrophysics Data System (ADS)

    Titus, Charles J.; Baker, Michael L.; Lee, Sang Jun; Cho, Hsiao-Mei; Doriese, William B.; Fowler, Joseph W.; Gaffney, Kelly; Gard, Johnathon D.; Hilton, Gene C.; Kenney, Chris; Knight, Jason; Li, Dale; Marks, Ronald; Minitti, Michael P.; Morgan, Kelsey M.; O'Neil, Galen C.; Reintsema, Carl D.; Schmidt, Daniel R.; Sokaras, Dimosthenis; Swetz, Daniel S.; Ullom, Joel N.; Weng, Tsu-Chien; Williams, Christopher; Young, Betty A.; Irwin, Kent D.; Solomon, Edward I.; Nordlund, Dennis

    2017-12-01

    We present X-ray absorption spectroscopy and resonant inelastic X-ray scattering (RIXS) measurements on the iron L-edge of 0.5 mM aqueous ferricyanide. These measurements demonstrate the ability of high-throughput transition-edge-sensor (TES) spectrometers to access the rich soft X-ray (100-2000 eV) spectroscopy regime for dilute and radiation-sensitive samples. Our low-concentration data are in agreement with high-concentration measurements recorded by grating spectrometers. These results show that soft-X-ray RIXS spectroscopy acquired by high-throughput TES spectrometers can be used to study the local electronic structure of dilute metal-centered complexes relevant to biology, chemistry, and catalysis. In particular, TES spectrometers have a unique ability to characterize frozen solutions of radiation- and temperature-sensitive samples.

  15. Edge detection for optical synthetic aperture based on deep neural network

    NASA Astrophysics Data System (ADS)

    Tan, Wenjie; Hui, Mei; Liu, Ming; Kong, Lingqin; Dong, Liquan; Zhao, Yuejin

    2017-09-01

    Synthetic aperture optics systems can meet the demands of the next-generation space telescopes being lighter, larger and foldable. However, the boundaries of segmented aperture systems are much more complex than that of the whole aperture. More edge regions mean more imaging edge pixels, which are often mixed and discretized. In order to achieve high-resolution imaging, it is necessary to identify the gaps between the sub-apertures and the edges of the projected fringes. In this work, we introduced the algorithm of Deep Neural Network into the edge detection of optical synthetic aperture imaging. According to the detection needs, we constructed image sets by experiments and simulations. Based on MatConvNet, a toolbox of MATLAB, we ran the neural network, trained it on training image set and tested its performance on validation set. The training was stopped when the test error on validation set stopped declining. As an input image is given, each intra-neighbor area around the pixel is taken into the network, and scanned pixel by pixel with the trained multi-hidden layers. The network outputs make a judgment on whether the center of the input block is on edge of fringes. We experimented with various pre-processing and post-processing techniques to reveal their influence on edge detection performance. Compared with the traditional algorithms or their improvements, our method makes decision on a much larger intra-neighbor, and is more global and comprehensive. Experiments on more than 2,000 images are also given to prove that our method outperforms classical algorithms in optical images-based edge detection.

  16. X-Ray Absorption Near-Edge Structure (XANES) Spectroscopy Study of the Interaction of Silver Ions with Staphylococcus aureus, Listeria monocytogenes, and Escherichia coli

    PubMed Central

    Zanzen, Ulrike; Krishna, Katla Sai; Hormes, Josef

    2013-01-01

    Silver ions are widely used as antibacterial agents, but the basic molecular mechanism of this effect is still poorly understood. X-ray absorption near-edge structure (XANES) spectroscopy at the Ag LIII, S K, and P K edges reveals the chemical forms of silver in Staphylococcus aureus and Escherichia coli (Ag+ treated). The Ag LIII-edge XANES spectra of the bacteria are all slightly different and very different from the spectra of silver ions (silver nitrate and silver acetate), which confirms that a reaction occurs. Death or inactivation of bacteria was observed by plate counting and light microscopy. Silver bonding to sulfhydryl groups (Ag-S) in cysteine and Ag-N or Ag-O bonding in histidine, alanine, and dl-aspartic acid was detected by using synthesized silver-amino acids. Significantly lower silver-cysteine content, coupled with higher silver-histidine content, in Gram-positive S. aureus and Listeria monocytogenes cells indicates that the peptidoglycan multilayer could be buffering the biocidal effect of silver on Gram-positive bacteria, at least in part. Bonding of silver to phosphate groups was not detected. Interaction with DNA or proteins can occur through Ag-N bonding. The formation of silver-cysteine can be confirmed for both bacterial cell types, which supports the hypothesis that enzyme-catalyzed reactions and the electron transport chain within the cell are disrupted. PMID:23934494

  17. Edge-SIFT: discriminative binary descriptor for scalable partial-duplicate mobile search.

    PubMed

    Zhang, Shiliang; Tian, Qi; Lu, Ke; Huang, Qingming; Gao, Wen

    2013-07-01

    As the basis of large-scale partial duplicate visual search on mobile devices, image local descriptor is expected to be discriminative, efficient, and compact. Our study shows that the popularly used histogram-based descriptors, such as scale invariant feature transform (SIFT) are not optimal for this task. This is mainly because histogram representation is relatively expensive to compute on mobile platforms and loses significant spatial clues, which are important for improving discriminative power and matching near-duplicate image patches. To address these issues, we propose to extract a novel binary local descriptor named Edge-SIFT from the binary edge maps of scale- and orientation-normalized image patches. By preserving both locations and orientations of edges and compressing the sparse binary edge maps with a boosting strategy, the final Edge-SIFT shows strong discriminative power with compact representation. Furthermore, we propose a fast similarity measurement and an indexing framework with flexible online verification. Hence, the Edge-SIFT allows an accurate and efficient image search and is ideal for computation sensitive scenarios such as a mobile image search. Experiments on a large-scale dataset manifest that the Edge-SIFT shows superior retrieval accuracy to Oriented BRIEF (ORB) and is superior to SIFT in the aspects of retrieval precision, efficiency, compactness, and transmission cost.

  18. Development of a new metal artifact reduction algorithm by using an edge preserving method for CBCT imaging

    NASA Astrophysics Data System (ADS)

    Kim, Juhye; Nam, Haewon; Lee, Rena

    2015-07-01

    CT (computed tomography) images, metal materials such as tooth supplements or surgical clips can cause metal artifact and degrade image quality. In severe cases, this may lead to misdiagnosis. In this research, we developed a new MAR (metal artifact reduction) algorithm by using an edge preserving filter and the MATLAB program (Mathworks, version R2012a). The proposed algorithm consists of 6 steps: image reconstruction from projection data, metal segmentation, forward projection, interpolation, applied edge preserving smoothing filter, and new image reconstruction. For an evaluation of the proposed algorithm, we obtained both numerical simulation data and data for a Rando phantom. In the numerical simulation data, four metal regions were added into the Shepp Logan phantom for metal artifacts. The projection data of the metal-inserted Rando phantom were obtained by using a prototype CBCT scanner manufactured by medical engineering and medical physics (MEMP) laboratory research group in medical science at Ewha Womans University. After these had been adopted the proposed algorithm was performed, and the result were compared with the original image (with metal artifact without correction) and with a corrected image based on linear interpolation. Both visual and quantitative evaluations were done. Compared with the original image with metal artifacts and with the image corrected by using linear interpolation, both the numerical and the experimental phantom data demonstrated that the proposed algorithm reduced the metal artifact. In conclusion, the evaluation in this research showed that the proposed algorithm outperformed the interpolation based MAR algorithm. If an optimization and a stability evaluation of the proposed algorithm can be performed, the developed algorithm is expected to be an effective tool for eliminating metal artifacts even in commercial CT systems.

  19. Soft x-ray coherent diffraction imaging on magnetic nanostructures

    NASA Astrophysics Data System (ADS)

    Shi, Xiaowen; Lee, James; Mishra, Shrawan; Parks, Daniel; Tyliszczak, Tolek; Shapiro, David; Roy, Sujoy; Kevan, Steve; Stxm Team At Als Collaboration; Soft X-Ray Microscopy Group At Als Collaboration; Soft X-ray scattering at ALS, LBL Team

    2014-03-01

    Coherent soft X-rays diffraction imaging enable coherent magnetic resonance scattering at transition metal L-edge to be probed so that magnetic domains could be imaged with very high spatial resolution with phase contrast, reaching sub-10nm. One of the overwhelming advantages of using coherent X-rays is the ability to resolve phase contrast images with linearly polarized light with both phase and absorption contrast comparing to real-space imaging, which can only be studied with circularly polarized light with absorption contrast only. Here we report our first results on high-resolution of magnetic domains imaging of CoPd multilayer thin film with coherent soft X-ray ptychography method. We are aiming to resolve and understand magnetic domain wall structures with the highest obtainable resolution here at Advanced Light Source. In principle types of magnetic domain walls could be studied so that Neel or Bloch walls can be distinguished by imaging. This work at LBNL was supported by the Director, Office of Science, Office of Basic Energy Sciences, of the US Department of Energy (contract no. DE-AC02- 05CH11231).

  20. Temperature and radiation effects at the fluorine K-edge in LiF

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Schwartz, Craig P.; Ponce, Francisco; Friedrich, Stephan

    Here, the fluorine K-edge of LiF is studied both experimentally and theoretically as a function of temperature. Instantaneous thermal fluctuations in atomic positions are shown in molecular dynamics simulations to increase in amplitude from 0.029 to 0.064 nm in the temperature range from 40 to 298 K. This is sufficient to cause instantaneous deviations from local octahedral atomic symmetry in this rock-salt crystal, resulting in altered electronic structure. The lowered symmetry of the lowest core-excited states of fluorine atoms is evident in X-ray absorption spectra at the F K-edge. In addition, sufficient radiation exposure produces a new X-ray absorption peak,more » below the F K-edge of LiF, which is assigned to defects in LiF based on both calculations and comparison to previous experiments.« less

  1. Temperature and radiation effects at the fluorine K-edge in LiF

    DOE PAGES

    Schwartz, Craig P.; Ponce, Francisco; Friedrich, Stephan; ...

    2017-05-30

    Here, the fluorine K-edge of LiF is studied both experimentally and theoretically as a function of temperature. Instantaneous thermal fluctuations in atomic positions are shown in molecular dynamics simulations to increase in amplitude from 0.029 to 0.064 nm in the temperature range from 40 to 298 K. This is sufficient to cause instantaneous deviations from local octahedral atomic symmetry in this rock-salt crystal, resulting in altered electronic structure. The lowered symmetry of the lowest core-excited states of fluorine atoms is evident in X-ray absorption spectra at the F K-edge. In addition, sufficient radiation exposure produces a new X-ray absorption peak,more » below the F K-edge of LiF, which is assigned to defects in LiF based on both calculations and comparison to previous experiments.« less

  2. Image compression technique

    DOEpatents

    Fu, Chi-Yung; Petrich, Loren I.

    1997-01-01

    An image is compressed by identifying edge pixels of the image; creating a filled edge array of pixels each of the pixels in the filled edge array which corresponds to an edge pixel having a value equal to the value of a pixel of the image array selected in response to the edge pixel, and each of the pixels in the filled edge array which does not correspond to an edge pixel having a value which is a weighted average of the values of surrounding pixels in the filled edge array which do correspond to edge pixels; and subtracting the filled edge array from the image array to create a difference array. The edge file and the difference array are then separately compressed and transmitted or stored. The original image is later reconstructed by creating a preliminary array in response to the received edge file, and adding the preliminary array to the received difference array. Filling is accomplished by solving Laplace's equation using a multi-grid technique. Contour and difference file coding techniques also are described. The techniques can be used in a method for processing a plurality of images by selecting a respective compression approach for each image, compressing each of the images according to the compression approach selected, and transmitting each of the images as compressed, in correspondence with an indication of the approach selected for the image.

  3. X-ray absorption spectroscopic studies of mononuclear non-heme iron enzymes

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Westre, Tami E.

    Fe-K-edge X-ray absorption spectroscopy (XAS) has been used to investigate the electronic and geometric structure of the iron active site in non-heme iron enzymes. A new theoretical extended X-ray absorption fine structure (EXAFS) analysis approach, called GNXAS, has been tested on data for iron model complexes to evaluate the utility and reliability of this new technique, especially with respect to the effects of multiple-scattering. In addition, a detailed analysis of the 1s→3d pre-edge feature has been developed as a tool for investigating the oxidation state, spin state, and geometry of iron sites. Edge and EXAFS analyses have then been appliedmore » to the study of non-heme iron enzyme active sites.« less

  4. A X-Ray Absorption Study of Transition Metal Oxides

    NASA Astrophysics Data System (ADS)

    Bunker, Grant Byrd

    This work is an experimental and theoretical study of the x-ray absorption near-edge structure of selected 3d transition metal compounds. The goal is to understand the physical mechanisms of XANES, using the competing multiple scattering (MS) and single scattering formalisms of Durham et al, and of Muller and Schaich, respectively. Careful experimental measurements of the K edge absorption of Mn oxides and KMnO(,4) at 300(DEGREES)K, 140(DEGREES)K and 80(DEGREES)K were made. These materials were chosen because they exhibit a variety of structures and oxidation states. Computer simulations of the XANES using the formalisms above were also performed. The experimental results show that atoms beyond the first coordination shell significantly affect the XANES near and above the edge; in particular the temperature dependent XANES and the "white line" in MnO establish this. We conclude that XANES, like EXAFS, is primarily sensitive to geometrical structure, except within about 1 Rydberg of the Fermi level. Two types of MS are distinguished: type 1 (forward scattering) is important in both XANES and EXAFS regions; type 2 (large angle scattering) is important only at and below the edge. MS of the photoelectron among the first shell Oxygen atoms in KMnO(,4) is observed experimentally, and found to become negligible above (DBLTURN) 1 Rydberg past the edge. The sharp features in XANES are primarily due to scattering from distant atoms, rather than localized states, except below the edge. This is supported by the observation that (alpha)-Mn(,2)O(,3) and Mn(,3)O(,4) spectra are nearly identical; their structures are the same, but the average oxidation states are different. We find the bond length strongly affects the edge position and the intensity of the 3d absorption in tetrahedrally coordinated transition metals. Other new results are the first shell EXAFS amplitude in MnO shows an anomalous energy dependence, which apparently cannot be explained by current theory. A new

  5. Combining Absorption and Dispersion Signals to Improve Signal-to-noise for Rapid Scan EPR Imaging

    PubMed Central

    Tseitlin, Mark; Quine, Richard W.; Rinard, George A.; Eaton, Sandra S.; Eaton, Gareth R.

    2010-01-01

    Direct detection of the rapid scan EPR signal with quadrature detection and without automatic frequency control provides both the absorption and dispersion components of the signal. The use of a cross-loop resonator results in similar signal-to-noise in the two channels. The dispersion signal can be converted to an equivalent absorption signal by means of Kramers-Kronig relations. The converted signal is added to the directly-measured absorption signal. Since the noise in the two channels is not correlated, this procedure increases the signal-to-noise ratio of the resultant absorption signal by up to a factor of √2. The utility of this method was demonstrated for 2D spectral-spatial imaging of a phantom containing 3 tubes of LiPc with different oxygen concentrations and therefore different linewidths. PMID:20181505

  6. A pre-edge analysis of Mn K-edge XANES spectra to help determine the speciation of manganese in minerals and glasses

    NASA Astrophysics Data System (ADS)

    Chalmin, E.; Farges, F.; Brown, G. E.

    2009-01-01

    High-resolution manganese K-edge X-ray absorption near edge structure spectra were collected on a set of 40 Mn-bearing minerals. The pre-edge feature information (position, area) was investigated to extract as much as possible quantitative valence and symmetry information for manganese in various “test” and “unknown” minerals and glasses. The samples present a range of manganese symmetry environments (tetrahedral, square planar, octahedral, and cubic) and valences (II to VII). The extraction of the pre-edge information is based on a previous multiple scattering and multiplet calculations for model compounds. Using the method described in this study, a robust estimation of the manganese valence could be obtained from the pre-edge region at 5% accuracy level. This method applied to 20 “test” compounds (such as hausmannite and rancieite) and to 15 “unknown” compounds (such as axinite and birnessite) provides a quantitative estimate of the average valence of manganese in complex minerals and silicate glasses.

  7. Anti-impulse-noise Edge Detection via Anisotropic Morphological Directional Derivatives.

    PubMed

    Shui, Peng-Lang; Wang, Fu-Ping

    2017-07-13

    Traditional differential-based edge detection suffers from abrupt degradation in performance when images are corrupted by impulse noises. The morphological operators such as the median filters and weighted median filters possess the intrinsic ability to counteract impulse noise. In this paper, by combining the biwindow configuration with weighted median filters, anisotropic morphological directional derivatives (AMDD) robust to impulse noise are proposed to measure the local grayscale variation around a pixel. For ideal step edges, the AMDD spatial response and directional representation are derived. The characteristics and edge resolution of two kinds of typical biwindows are analyzed thoroughly. In terms of the AMDD spatial response and directional representation of ideal step edges, the spatial matched filter is used to extract the edge strength map (ESM) from the AMDDs of an image. The spatial and directional matched filters are used to extract the edge direction map (EDM). Embedding the extracted ESM and EDM into the standard route of the differential-based edge detection, an anti-impulse-noise AMDD-based edge detector is constructed. It is compared with the existing state-of-the-art detectors on a recognized image dataset for edge detection evaluation. The results show that it attains competitive performance in noise-free and Gaussian noise cases and the best performance in impulse noise cases.

  8. Information theoretic analysis of linear shift-invariant edge-detection operators

    NASA Astrophysics Data System (ADS)

    Jiang, Bo; Rahman, Zia-ur

    2012-06-01

    Generally, the designs of digital image processing algorithms and image gathering devices remain separate. Consequently, the performance of digital image processing algorithms is evaluated without taking into account the influences by the image gathering process. However, experiments show that the image gathering process has a profound impact on the performance of digital image processing and the quality of the resulting images. Huck et al. proposed one definitive theoretic analysis of visual communication channels, where the different parts, such as image gathering, processing, and display, are assessed in an integrated manner using Shannon's information theory. We perform an end-to-end information theory based system analysis to assess linear shift-invariant edge-detection algorithms. We evaluate the performance of the different algorithms as a function of the characteristics of the scene and the parameters, such as sampling, additive noise etc., that define the image gathering system. The edge-detection algorithm is regarded as having high performance only if the information rate from the scene to the edge image approaches its maximum possible. This goal can be achieved only by jointly optimizing all processes. Our information-theoretic assessment provides a new tool that allows us to compare different linear shift-invariant edge detectors in a common environment.

  9. Speciation of sulfur in humic and fulvic acids using X-ray absorption near-edge structure (XANES) spectroscopy

    NASA Astrophysics Data System (ADS)

    Morra, Matthew J.; Fendorf, Scott E.; Brown, Paul D.

    1997-02-01

    Sulfur species in soils and sediments have previously been determined indirectly using destructive techniques. A direct and more accurate method for S speciation would improve our understanding of S biogeochemistry. X-ray absorption near edge structure (XANES) spectroscopy was performed on purified humic and fulvic acids from terrestrial and aquatic environments. This methodology allows direct determination of S species using the relationship that exists with the energy required for core electron transitions and in some cases, correlation with additional spectral features. Soil, peat, and aquatic humic acids were dominated by sulfonates with an oxidation state of +5, but also contained ester-bonded sulfates with an oxidation state of +6. Leonardite humic acid contained ester-bonded sulfate and an unidentified S compound with an oxidation state of +4.0. In contrast, high-valent S in soil, peat, and aquatic fulvic acids was exclusively in the form of sulfonic acids. Reduced S species were also present in both humic and fulvic acids. XANES is a valuable method for the speciation of S in humic materials and of potential use in S speciation of unfractionated soils.

  10. Analysis of airborne imaging spectrometer data for the Ruby Mountains, Montana, by use of absorption-band-depth images

    NASA Technical Reports Server (NTRS)

    Brickey, David W.; Crowley, James K.; Rowan, Lawrence C.

    1987-01-01

    Airborne Imaging Spectrometer-1 (AIS-1) data were obtained for an area of amphibolite grade metamorphic rocks that have moderate rangeland vegetation cover. Although rock exposures are sparse and patchy at this site, soils are visible through the vegetation and typically comprise 20 to 30 percent of the surface area. Channel averaged low band depth images for diagnostic soil rock absorption bands. Sets of three such images were combined to produce color composite band depth images. This relative simple approach did not require extensive calibration efforts and was effective for discerning a number of spectrally distinctive rocks and soils, including soils having high talc concentrations. The results show that the high spectral and spatial resolution of AIS-1 and future sensors hold considerable promise for mapping mineral variations in soil, even in moderately vegetated areas.

  11. Image compression technique

    DOEpatents

    Fu, C.Y.; Petrich, L.I.

    1997-03-25

    An image is compressed by identifying edge pixels of the image; creating a filled edge array of pixels each of the pixels in the filled edge array which corresponds to an edge pixel having a value equal to the value of a pixel of the image array selected in response to the edge pixel, and each of the pixels in the filled edge array which does not correspond to an edge pixel having a value which is a weighted average of the values of surrounding pixels in the filled edge array which do correspond to edge pixels; and subtracting the filled edge array from the image array to create a difference array. The edge file and the difference array are then separately compressed and transmitted or stored. The original image is later reconstructed by creating a preliminary array in response to the received edge file, and adding the preliminary array to the received difference array. Filling is accomplished by solving Laplace`s equation using a multi-grid technique. Contour and difference file coding techniques also are described. The techniques can be used in a method for processing a plurality of images by selecting a respective compression approach for each image, compressing each of the images according to the compression approach selected, and transmitting each of the images as compressed, in correspondence with an indication of the approach selected for the image. 16 figs.

  12. In-flight edge response measurements for high-spatial-resolution remote sensing systems

    NASA Astrophysics Data System (ADS)

    Blonski, Slawomir; Pagnutti, Mary A.; Ryan, Robert; Zanoni, Vickie

    2002-09-01

    In-flight measurements of spatial resolution were conducted as part of the NASA Scientific Data Purchase Verification and Validation process. Characterization included remote sensing image products with ground sample distance of 1 meter or less, such as those acquired with the panchromatic imager onboard the IKONOS satellite and the airborne ADAR System 5500 multispectral instrument. Final image products were used to evaluate the effects of both the image acquisition system and image post-processing. Spatial resolution was characterized by full width at half maximum of an edge-response-derived line spread function. The edge responses were analyzed using the tilted-edge technique that overcomes the spatial sampling limitations of the digital imaging systems. As an enhancement to existing algorithms, the slope of the edge response and the orientation of the edge target were determined by a single computational process. Adjacent black and white square panels, either painted on a flat surface or deployed as tarps, formed the ground-based edge targets used in the tests. Orientation of the deployable tarps was optimized beforehand, based on simulations of the imaging system. The effects of such factors as acquisition geometry, temporal variability, Modulation Transfer Function compensation, and ground sample distance on spatial resolution were investigated.

  13. L-edge spectroscopy of dilute, radiation-sensitive systems using a transition-edge-sensor array

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Titus, Charles J.; Baker, Michael L.; Lee, Sang Jun

    Here, we present X-ray absorption spectroscopy and resonant inelastic X-ray scattering (RIXS) measurements on the iron L-edge of 0.5 mM aqueous ferricyanide. These measurements then demonstrate the ability of high-throughput transition-edge-sensor (TES) spectrometers to access the rich soft X-ray (100–2000 eV) spectroscopy regime for dilute and radiation-sensitive samples. Our low-concentration data are in agreement with high-concentration measurements recorded by grating spectrometers. These results show that soft-X-ray RIXS spectroscopy acquired by high-throughput TES spectrometers can be used to study the local electronic structure of dilute metal-centered complexes relevant to biology, chemistry, and catalysis. In particular, TES spectrometers have a unique abilitymore » to characterize frozen solutions of radiation- and temperature-sensitive samples.« less

  14. L-edge spectroscopy of dilute, radiation-sensitive systems using a transition-edge-sensor array

    DOE PAGES

    Titus, Charles J.; Baker, Michael L.; Lee, Sang Jun; ...

    2017-12-07

    Here, we present X-ray absorption spectroscopy and resonant inelastic X-ray scattering (RIXS) measurements on the iron L-edge of 0.5 mM aqueous ferricyanide. These measurements then demonstrate the ability of high-throughput transition-edge-sensor (TES) spectrometers to access the rich soft X-ray (100–2000 eV) spectroscopy regime for dilute and radiation-sensitive samples. Our low-concentration data are in agreement with high-concentration measurements recorded by grating spectrometers. These results show that soft-X-ray RIXS spectroscopy acquired by high-throughput TES spectrometers can be used to study the local electronic structure of dilute metal-centered complexes relevant to biology, chemistry, and catalysis. In particular, TES spectrometers have a unique abilitymore » to characterize frozen solutions of radiation- and temperature-sensitive samples.« less

  15. Investigation of Pb species in soils, celery and duckweed by synchrotron radiation X-ray absorption near-edge structure spectrometry

    NASA Astrophysics Data System (ADS)

    Luo, Liqiang; Shen, Yating; Liu, Jian; Zeng, Yuan

    2016-08-01

    The Pb species play a key role in its translocation in biogeochemical cycles. Soils, sediments and plants were collected from farmlands around Pb mines, and the Pb species in them was identified by X-ray absorption near-edge structure spectrometry. In soils, Pb5(PO4)3Cl and Pb3(PO4)2 were detected, and in sediments, Pb-fulvic acids (FAs) complex was identified. A Pb complex with FA fragments was also detected in celery samples. We found that (1) different Pb species were present in soils and sediments; (2) the Pb species in celery, which was grown in sediments, was different from the species present in duckweed, which grew in water; and (3) a Pb-FA-like compound was present in celery roots. The newly identified Pb species, the Pb-FA-like compound, may play a key role in Pb tolerance and translocation within plants.

  16. X-ray absorption spectroscopic studies of the active sites of nickel- and copper-containing metalloproteins

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Tan, Grace O.

    1993-06-01

    X-ray absorption spectroscopy (XAS) is a useful tool for obtaining structural and chemical information about the active sites of metalloproteins and metalloenzymes. Information may be obtained from both the edge region and the extended X-ray absorption fine structure (EXAFS) or post-edge region of the K-edge X-ray absorption spectrum of a metal center in a compound. The edge contains information about the valence electronic structure of the atom that absorbs the X-rays. It is possible in some systems to infer the redox state of the metal atom in question, as well as the geometry and nature of ligands connected to it,more » from the features in the edge in a straightforward manner. The EXAFS modulations, being produced by the backscattering of the ejected photoelectron from the atoms surrounding the metal atom, provide, when analyzed, information about the number and type of neighbouring atoms, and the distances at which they occur. In this thesis, analysis of both the edge and EXAFS regions has been used to gain information about the active sites of various metalloproteins. The metalloproteins studied were plastocyanin (Pc), laccase and nickel carbon monoxide dehydrogenase (Ni CODH). Studies of Cu(I)-imidazole compounds, related to the protein hemocyanin, are also reported here.« less

  17. Benefits of Red-Edge Spectral Band and Texture Features for the Object-based Classification using RapidEye sSatellite Image data

    NASA Astrophysics Data System (ADS)

    Kim, H. O.; Yeom, J. M.

    2014-12-01

    Space-based remote sensing in agriculture is particularly relevant to issues such as global climate change, food security, and precision agriculture. Recent satellite missions have opened up new perspectives by offering high spatial resolution, various spectral properties, and fast revisit rates to the same regions. Here, we examine the utility of broadband red-edge spectral information in multispectral satellite image data for classifying paddy rice crops in South Korea. Additionally, we examine how object-based spectral features affect the classification of paddy rice growth stages. For the analysis, two seasons of RapidEye satellite image data were used. The results showed that the broadband red-edge information slightly improved the classification accuracy of the crop condition in heterogeneous paddy rice crop environments, particularly when single-season image data were used. This positive effect appeared to be offset by the multi-temporal image data. Additional texture information brought only a minor improvement or a slight decline, although it is well known to be advantageous for object-based classification in general. We conclude that broadband red-edge information derived from conventional multispectral satellite data has the potential to improve space-based crop monitoring. Because the positive or negative effects of texture features for object-based crop classification could barely be interpreted, the relationships between the textual properties and paddy rice crop parameters at the field scale should be further examined in depth.

  18. The protonation states of oxo-bridged Mn(IV) dimers resolved by experimental and computational Mn K pre-edge X-ray absorption spectroscopy.

    PubMed

    Krewald, Vera; Lassalle-Kaiser, Benedikt; Boron, Thaddeus T; Pollock, Christopher J; Kern, Jan; Beckwith, Martha A; Yachandra, Vittal K; Pecoraro, Vincent L; Yano, Junko; Neese, Frank; DeBeer, Serena

    2013-11-18

    In nature, the protonation of oxo bridges is a commonly encountered mechanism for fine-tuning chemical properties and reaction pathways. Often, however, the protonation states are difficult to establish experimentally. This is of particular importance in the oxygen evolving complex of photosystem II, where identification of the bridging oxo protonation states is one of the essential requirements toward unraveling the mechanism. In order to establish a combined experimental and theoretical protocol for the determination of protonation states, we have systematically investigated a series of Mn model complexes by Mn K pre-edge X-ray absorption spectroscopy. An ideal test case for selective bis-μ-oxo-bridge protonation in a Mn dimer is represented by the system [Mn(IV)2(salpn)2(μ-OHn)2](n+). Although the three species [Mn(IV)2(salpn)2(μ-O)2], [Mn(IV)2(salpn)2(μ-O)(μ-OH)](+) and [Mn(IV)2(salpn)2(μ-OH)2](2+) differ only in the protonation of the oxo bridges, they exhibit distinct differences in the pre-edge region while maintaining the same edge energy. The experimental spectra are correlated in detail to theoretically calculated spectra. A time-dependent density functional theory approach for calculating the pre-edge spectra of molecules with multiple metal centers is presented, using both high spin (HS) and broken symmetry (BS) electronic structure solutions. The most intense pre-edge transitions correspond to an excitation of the Mn 1s core electrons into the unoccupied orbitals of local e(g) character (d(z)(2) and d(xy) based in the chosen coordinate system). The lowest energy experimental feature is dominated by excitations of 1s-α electrons, and the second observed feature is primarily attributed to 1s-β electron excitations. The observed energetic separation is due to spin polarization effects in spin-unrestricted density functional theory and models final state multiplet effects. The effects of spin polarization on the calculated Mn K pre-edge spectra, in

  19. Time-resolved photoion imaging spectroscopy: Determining energy distribution in multiphoton absorption experiments

    NASA Astrophysics Data System (ADS)

    Qian, D. B.; Shi, F. D.; Chen, L.; Martin, S.; Bernard, J.; Yang, J.; Zhang, S. F.; Chen, Z. Q.; Zhu, X. L.; Ma, X.

    2018-04-01

    We propose an approach to determine the excitation energy distribution due to multiphoton absorption in the case of excited systems following decays to produce different ion species. This approach is based on the measurement of the time-resolved photoion position spectrum by using velocity map imaging spectrometry and an unfocused laser beam with a low fluence and homogeneous profile. Such a measurement allows us to identify the species and the origin of each ion detected and to depict the energy distribution using a pure Poisson's equation involving only one variable which is proportional to the absolute photon absorption cross section. A cascade decay model is used to build direct connections between the energy distribution and the probability to detect each ionic species. Comparison between experiments and simulations permits the energy distribution and accordingly the absolute photon absorption cross section to be determined. This approach is illustrated using C60 as an example. It may therefore be extended to a wide variety of molecules and clusters having decay mechanisms similar to those of fullerene molecules.

  20. Laser line illumination scheme allowing the reduction of background signal and the correction of absorption heterogeneities effects for fluorescence reflectance imaging.

    PubMed

    Fantoni, Frédéric; Hervé, Lionel; Poher, Vincent; Gioux, Sylvain; Mars, Jérôme I; Dinten, Jean-Marc

    2015-10-01

    Intraoperative fluorescence imaging in reflectance geometry is an attractive imaging modality as it allows to noninvasively monitor the fluorescence targeted tumors located below the tissue surface. Some drawbacks of this technique are the background fluorescence decreasing the contrast and absorption heterogeneities leading to misinterpretations concerning fluorescence concentrations. We propose a correction technique based on a laser line scanning illumination scheme. We scan the medium with the laser line and acquire, at each position of the line, both fluorescence and excitation images. We then use the finding that there is a relationship between the excitation intensity profile and the background fluorescence one to predict the amount of signal to subtract from the fluorescence images to get a better contrast. As the light absorption information is contained both in fluorescence and excitation images, this method also permits us to correct the effects of absorption heterogeneities. This technique has been validated on simulations and experimentally. Fluorescent inclusions are observed in several configurations at depths ranging from 1 mm to 1 cm. Results obtained with this technique are compared with those obtained with a classical wide-field detection scheme for contrast enhancement and with the fluorescence by an excitation ratio approach for absorption correction.

  1. Comparing Broad-Band and Red Edge-Based Spectral Vegetation Indices to Estimate Nitrogen Concentration of Crops Using Casi Data

    NASA Astrophysics Data System (ADS)

    Wang, Yanjie; Liao, Qinhong; Yang, Guijun; Feng, Haikuan; Yang, Xiaodong; Yue, Jibo

    2016-06-01

    In recent decades, many spectral vegetation indices (SVIs) have been proposed to estimate the leaf nitrogen concentration (LNC) of crops. However, most of these indices were based on the field hyperspectral reflectance. To test whether they can be used in aerial remote platform effectively, in this work a comparison of the sensitivity between several broad-band and red edge-based SVIs to LNC is investigated over different crop types. By using data from experimental LNC values over 4 different crop types and image data acquired using the Compact Airborne Spectrographic Imager (CASI) sensor, the extensive dataset allowed us to evaluate broad-band and red edge-based SVIs. The result indicated that NDVI performed the best among the selected SVIs while red edge-based SVIs didn't show the potential for estimating the LNC based on the CASI data due to the spectral resolution. In order to search for the optimal SVIs, the band combination algorithm has been used in this work. The best linear correlation against the experimental LNC dataset was obtained by combining the 626.20nm and 569.00nm wavebands. These wavelengths correspond to the maximal chlorophyll absorption and reflection position region, respectively, and are known to be sensitive to the physiological status of the plant. Then this linear relationship was applied to the CASI image for generating an LNC map, which can guide farmers in the accurate application of their N fertilization strategies.

  2. Systematic oxidation of polystyrene by ultraviolet-ozone, characterized by near-edge X-ray absorption fine structure and contact angle.

    PubMed

    Klein, Robert J; Fischer, Daniel A; Lenhart, Joseph L

    2008-08-05

    The process of implanting oxygen in polystyrene (PS) via exposure to ultraviolet-ozone (UV-O) was systematically investigated using the characterization technique of near-edge X-ray absorption fine structure (NEXAFS). Samples of PS exposed to UV-O for 10-300 s and washed with isopropanol were analyzed using the carbon and oxygen K-edge NEXAFS partial electron yields, using various retarding bias voltages to depth-profile the oxygen penetration into the surface. Evaluation of reference polymers provided a scale to quantify the oxygen concentration implanted by UV-O treatment. We find that ozone initially reacts with the double bonds on the phenyl rings, forming carbonyl groups, but within 1 min of exposure, the ratio of double to single oxygen bonds stabilizes at a lower value. Oxygen penetrates the film with relative ease, creating a fairly uniform distribution of oxygen within at least the first 4 nm (the effective depth probed by NEXAFS here). Before oxygen accumulates in large concentrations, however, it preferentially degrades the uppermost layer of the film by removing oxygenated low-molecular-weight oligomers. The failure to accumulate high concentrations of oxygen is seen in the nearly constant carbon edge jump, the low concentration of oxygen even at 5 min exposure (58% of that in poly(4-acetoxystyrene), the polymer with the most similarities to UV-O-treated PS), and the relatively high contact angles. At 5 min exposure the oxygen concentration contains ca. 7 atomic % oxygen. The oxygen species that are implanted consist predominantly of single O-C bonds and double O=C bonds but also include a small fraction of O-H. UV-O treatment leads a plateau after 2 min exposure in the water contact angle hysteresis, at a value of 67 +/- 2 degrees , due primarily to chemical heterogeneity. Annealing above T(g) allows oxygenated species to move short distances away from the surface but not diffuse further than 1-2 nm.

  3. An automatic optimum kernel-size selection technique for edge enhancement

    USGS Publications Warehouse

    Chavez, Pat S.; Bauer, Brian P.

    1982-01-01

    Edge enhancement is a technique that can be considered, to a first order, a correction for the modulation transfer function of an imaging system. Digital imaging systems sample a continuous function at discrete intervals so that high-frequency information cannot be recorded at the same precision as lower frequency data. Because of this, fine detail or edge information in digital images is lost. Spatial filtering techniques can be used to enhance the fine detail information that does exist in the digital image, but the filter size is dependent on the type of area being processed. A technique has been developed by the authors that uses the horizontal first difference to automatically select the optimum kernel-size that should be used to enhance the edges that are contained in the image

  4. Phosphorus K-edge XANES spectroscopy of mineral standards

    PubMed Central

    Ingall, Ellery D.; Brandes, Jay A.; Diaz, Julia M.; de Jonge, Martin D.; Paterson, David; McNulty, Ian; Elliott, W. Crawford; Northrup, Paul

    2011-01-01

    Phosphorus K-edge X-ray absorption near-edge structure (XANES) spectroscopy was performed on phosphate mineral specimens including (a) twelve specimens from the apatite group covering a range of compositional variation and crystallinity; (b) six non-apatite calcium-rich phosphate minerals; (c) 15 aluminium-rich phosphate minerals; (d) ten phosphate minerals rich in either reduced iron or manganese; (e) four phosphate minerals rich in either oxidized iron or manganese; (f) eight phosphate minerals rich in either magnesium, copper, lead, zinc or rare-earth elements; and (g) four uranium phosphate minerals. The identity of all minerals examined in this study was independently confirmed using X-ray powder diffraction. Minerals were distinguished using XANES spectra with a combination of pre-edge features, edge position, peak shapes and post-edge features. Shared spectral features were observed in minerals with compositions dominated by the same specific cation. Analyses of apatite-group minerals indicate that XANES spectral patterns are not strongly affected by variations in composition and crystallinity typical of natural mineral specimens. PMID:21335905

  5. Improvement and implementation for Canny edge detection algorithm

    NASA Astrophysics Data System (ADS)

    Yang, Tao; Qiu, Yue-hong

    2015-07-01

    Edge detection is necessary for image segmentation and pattern recognition. In this paper, an improved Canny edge detection approach is proposed due to the defect of traditional algorithm. A modified bilateral filter with a compensation function based on pixel intensity similarity judgment was used to smooth image instead of Gaussian filter, which could preserve edge feature and remove noise effectively. In order to solve the problems of sensitivity to the noise in gradient calculating, the algorithm used 4 directions gradient templates. Finally, Otsu algorithm adaptively obtain the dual-threshold. All of the algorithm simulated with OpenCV 2.4.0 library in the environments of vs2010, and through the experimental analysis, the improved algorithm has been proved to detect edge details more effectively and with more adaptability.

  6. Extraction of edge-based and region-based features for object recognition

    NASA Astrophysics Data System (ADS)

    Coutts, Benjamin; Ravi, Srinivas; Hu, Gongzhu; Shrikhande, Neelima

    1993-08-01

    One of the central problems of computer vision is object recognition. A catalogue of model objects is described as a set of features such as edges and surfaces. The same features are extracted from the scene and matched against the models for object recognition. Edges and surfaces extracted from the scenes are often noisy and imperfect. In this paper algorithms are described for improving low level edge and surface features. Existing edge extraction algorithms are applied to the intensity image to obtain edge features. Initial edges are traced by following directions of the current contour. These are improved by using corresponding depth and intensity information for decision making at branch points. Surface fitting routines are applied to the range image to obtain planar surface patches. An algorithm of region growing is developed that starts with a coarse segmentation and uses quadric surface fitting to iteratively merge adjacent regions into quadric surfaces based on approximate orthogonal distance regression. Surface information obtained is returned to the edge extraction routine to detect and remove fake edges. This process repeats until no more merging or edge improvement can take place. Both synthetic (with Gaussian noise) and real images containing multiple object scenes have been tested using the merging criteria. Results appeared quite encouraging.

  7. An Iris Segmentation Algorithm based on Edge Orientation for Off-angle Iris Recognition

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Karakaya, Mahmut; Barstow, Del R; Santos-Villalobos, Hector J

    Iris recognition is known as one of the most accurate and reliable biometrics. However, the accuracy of iris recognition systems depends on the quality of data capture and is negatively affected by several factors such as angle, occlusion, and dilation. In this paper, we present a segmentation algorithm for off-angle iris images that uses edge detection, edge elimination, edge classification, and ellipse fitting techniques. In our approach, we first detect all candidate edges in the iris image by using the canny edge detector; this collection contains edges from the iris and pupil boundaries as well as eyelash, eyelids, iris texturemore » etc. Edge orientation is used to eliminate the edges that cannot be part of the iris or pupil. Then, we classify the remaining edge points into two sets as pupil edges and iris edges. Finally, we randomly generate subsets of iris and pupil edge points, fit ellipses for each subset, select ellipses with similar parameters, and average to form the resultant ellipses. Based on the results from real experiments, the proposed method shows effectiveness in segmentation for off-angle iris images.« less

  8. Multi-exponential analysis of magnitude MR images using a quantitative multispectral edge-preserving filter.

    PubMed

    Bonny, Jean Marie; Boespflug-Tanguly, Odile; Zanca, Michel; Renou, Jean Pierre

    2003-03-01

    A solution for discrete multi-exponential analysis of T(2) relaxation decay curves obtained in current multi-echo imaging protocol conditions is described. We propose a preprocessing step to improve the signal-to-noise ratio and thus lower the signal-to-noise ratio threshold from which a high percentage of true multi-exponential detection is detected. It consists of a multispectral nonlinear edge-preserving filter that takes into account the signal-dependent Rician distribution of noise affecting magnitude MR images. Discrete multi-exponential decomposition, which requires no a priori knowledge, is performed by a non-linear least-squares procedure initialized with estimates obtained from a total least-squares linear prediction algorithm. This approach was validated and optimized experimentally on simulated data sets of normal human brains.

  9. A Fast Superpixel Segmentation Algorithm for PolSAR Images Based on Edge Refinement and Revised Wishart Distance

    PubMed Central

    Zhang, Yue; Zou, Huanxin; Luo, Tiancheng; Qin, Xianxiang; Zhou, Shilin; Ji, Kefeng

    2016-01-01

    The superpixel segmentation algorithm, as a preprocessing technique, should show good performance in fast segmentation speed, accurate boundary adherence and homogeneous regularity. A fast superpixel segmentation algorithm by iterative edge refinement (IER) works well on optical images. However, it may generate poor superpixels for Polarimetric synthetic aperture radar (PolSAR) images due to the influence of strong speckle noise and many small-sized or slim regions. To solve these problems, we utilized a fast revised Wishart distance instead of Euclidean distance in the local relabeling of unstable pixels, and initialized unstable pixels as all the pixels substituted for the initial grid edge pixels in the initialization step. Then, postprocessing with the dissimilarity measure is employed to remove the generated small isolated regions as well as to preserve strong point targets. Finally, the superiority of the proposed algorithm is validated with extensive experiments on four simulated and two real-world PolSAR images from Experimental Synthetic Aperture Radar (ESAR) and Airborne Synthetic Aperture Radar (AirSAR) data sets, which demonstrate that the proposed method shows better performance with respect to several commonly used evaluation measures, even with about nine times higher computational efficiency, as well as fine boundary adherence and strong point targets preservation, compared with three state-of-the-art methods. PMID:27754385

  10. Complex Resonance Absorption Structure in the X-Ray Spectrum of IRAS 13349+2438

    NASA Technical Reports Server (NTRS)

    Sako, M.; Kahn, S. M.; Behar, E.; Kaastra, J. S.; Brinkman, A. C.; Boller, Th.; Puchnarewicz, E. M.; Starling, R.; Liedahl, D. A.; Clavel, J.

    2000-01-01

    The luminous infrared-loud quasar IRAS 13349+2438 was observed with the XMM - Newton Observatory as part of the Performance Verification program. The spectrum obtained by the Reflection Grating Spectrometer (RGS) exhibits broad (FWHM - 1400 km/s) absorption lines from highly ionized elements including hydrogen- and helium-like carbon, nitrogen, oxygen, and neon, and several iron L - shell ions (Fe XVII - XX). Also shown in the spectrum is the first astrophysical detection of a broad absorption feature around lambda = 16 - 17 A identified as an unresolved transition array (UTA) of 2p - 3d inner-shell absorption by iron M-shell ions in a much cooler medium; a feature that might be misidentified as an O VII edge when observed with moderate resolution spectrometers. No absorption edges are clearly detected in the spectrum. We demonstrate that the RGS spectrum of IRAS 13349+2438 exhibits absorption lines from two distinct regions, one of which is tentatively associated with the medium that produces the optical/UV reddening.

  11. Localized modes in optics of photonic liquid crystals with local anisotropy of absorption

    NASA Astrophysics Data System (ADS)

    Belyakov, V. A.; Semenov, S. V.

    2016-05-01

    The localized optical modes in spiral photonic liquid crystals are theoretically studied for the certainty at the example of chiral liquid crystals (CLCs) for the case of CLC with an anisotropic local absorption. The model adopted here (absence of dielectric interfaces in the structures under investigation) makes it possible to get rid of mixing of polarizations on the surfaces of the CLC layer and of the defect structure and to reduce the corresponding equations to only the equations for light with polarization diffracting in the CLC. The dispersion equations determining connection of the edge mode (EM) and defect mode (DM) frequencies with the CLC layer parameters (anisotropy of local absorption, CLC order parameter) and other parameters of the DMS are obtained. Analytic expressions for the transmission and reflection coefficients of CLC layer and DMS for the case of CLC with an anisotropic local absorption are presented and analyzed. It is shown that the CLC layers with locally anisotropic absorption reduce the EM and DM lifetimes (and increase the lasing threshold) in the way different from the case of CLC with an isotropic local absorption. Due to the Borrmann effect revealing of which is different at the opposite stop-band edges in the case of CLC layers with an anisotropic local absorption the EM life-times for the EM frequencies at the opposite stop-bands edges may be significantly different. The options of experimental observations of the theoretically revealed phenomena are briefly discussed.

  12. Direct determination of oxidation state of gold deposits in metal-reducing bacterium Shewanella algae using X-ray absorption near-edge structure spectroscopy (XANES).

    PubMed

    Konishi, Yasuhiro; Tsukiyama, Takeshi; Saitoh, Norizoh; Nomura, Toshiyuki; Nagamine, Shinsuke; Takahashi, Yoshio; Uruga, Tomoya

    2007-06-01

    X-ray absorption near-edge structure spectroscopy (XANES) was successfully employed to determine the gold valence in the metal-reducing bacterium Shewanella algae after exposure to a 1 mM aqueous HAuCl4 solution for 10-120 min. XANES spectra revealed the oxidation state of gold in the bacterial cells to be Au(0) without any contribution from Au(III), demonstrating that S. algae cells can reduce AuCl4- ions to elemental gold. Transmission electron microscopy (TEM) and energy dispersive X-ray (EDX) analysis confirmed that gold nanoparticles 5-15 nm in size were deposited in the periplasmic space of the bacterial cells; a preferable, cell surface location for the easy recovery of biogenic nanoparticles.

  13. Image flows and one-liner graphical image representation.

    PubMed

    Makhervaks, Vadim; Barequet, Gill; Bruckstein, Alfred

    2002-10-01

    This paper introduces a novel graphical image representation consisting of a single curve-the one-liner. The first step of the algorithm involves the detection and ranking of image edges. A new edge exploration technique is used to perform both tasks simultaneously. This process is based on image flows. It uses a gradient vector field and a new operator to explore image edges. Estimation of the derivatives of the image is performed by using local Taylor expansions in conjunction with a weighted least-squares method. This process finds all the possible image edges without any pruning, and collects information that allows the edges found to be prioritized. This enables the most important edges to be selected to form a skeleton of the representation sought. The next step connects the selected edges into one continuous curve-the one-liner. It orders the selected edges and determines the curves connecting them. These two problems are solved separately. Since the abstract graph setting of the first problem is NP-complete, we reduce it to a variant of the traveling salesman problem and compute an approximate solution to it. We solve the second problem by using Dijkstra's shortest-path algorithm. The full software implementation for the entire one-liner determination process is available.

  14. Complex polarization propagator approach in the restricted open-shell, self-consistent field approximation: the near K-edge X-ray absorption fine structure spectra of allyl and copper phthalocyanine.

    PubMed

    Linares, Mathieu; Stafström, Sven; Rinkevicius, Zilvinas; Ågren, Hans; Norman, Patrick

    2011-05-12

    A presentation of the complex polarization propagator in the restricted open-shell self-consistent field approximation is given. It rests on a formulation of a resonant-convergent, first-order polarization propagator approach that makes it possible to directly calculate the X-ray absorption cross section at a particular frequency without explicitly addressing the excited states. The quality of the predicted X-ray spectra relates only to the type of density functional applied without any separate treatment of dynamical relaxation effects. The method is applied to the calculation of the near K-edge X-ray absorption fine structure spectra of allyl and copper phthalocyanine. Comparison is made between the spectra of the radicals and those of the corresponding cations and anions to assess the effect of the increase of electron charge in the frontier orbital. The method offers the possibility for unique assignment of symmetry-independent atoms. The overall excellent spectral agreement motivates the application of the method as a routine precise tool for analyzing X-ray absorption of large systems of technological interest.

  15. Iron L-edge X-ray Absorption Spectroscopy of Oxy-Picket Fence Porphyrin: Experimental Insight into Fe-O2 Bonding

    PubMed Central

    Wilson, Samuel A.; Kroll, Thomas; Decreau, Richard A.; Hocking, Rosalie K.; Lundberg, Marcus; Hedman, Britt; Hodgson, Keith O.; Solomon, Edward I.

    2013-01-01

    The electronic structure of the Fe–O2 center in oxy-hemoglobin and oxy-myoglobin is a long-standing issue in the field of bioinorganic chemistry. Spectroscopic studies have been complicated by the highly delocalized nature of the porphyrin and calculations require interpretation of multi-determinant wavefunctions for a highly covalent metal site. Here, iron L-edge X-ray absorption spectroscopy (XAS), interpreted using a valence bond configuration interaction (VBCI) multiplet model, is applied to directly probe the electronic structure of the iron in the biomimetic Fe–O2 heme complex [Fe(pfp)(1-MeIm)O2] (pfp = meso-tetra(α,α,α,α-o-pivalamidophenyl) porphyrin or TpivPP). This method allows separate estimates of σ-donor, π-donor, and π-acceptor interactions through ligand to metal charge transfer (LMCT) and metal to ligand charge transfer (MLCT) mixing pathways. The L-edge spectrum of [Fe(pfp)(1-MeIm)O2] is further compared to those of [FeII(pfp)(1-MeIm)2], [FeII(pfp)], and [FeIII(tpp)(ImH)2]Cl (tpp = meso-tetraphenylporphyrin) which have FeII S = 0, FeII S = 1 and FeIII S = 1/2 ground states, respectively. These serve as references for the three possible contributions to the ground state of oxy-pfp. The Fe–O2 pfp site is experimentally determined to have both significant σ-donation and a strong π-interaction of the O2 with the iron, with the latter having implications with respect to the spin polarization of the ground state. PMID:23259487

  16. Tetrahalide complexes of the [U(NR)2]2+ ion: synthesis, theory, and chlorine K-edge X-ray absorption spectroscopy.

    PubMed

    Spencer, Liam P; Yang, Ping; Minasian, Stefan G; Jilek, Robert E; Batista, Enrique R; Boland, Kevin S; Boncella, James M; Conradson, Steven D; Clark, David L; Hayton, Trevor W; Kozimor, Stosh A; Martin, Richard L; MacInnes, Molly M; Olson, Angela C; Scott, Brian L; Shuh, David K; Wilkerson, Marianne P

    2013-02-13

    Synthetic routes to salts containing uranium bis-imido tetrahalide anions [U(NR)(2)X(4)](2-) (X = Cl(-), Br(-)) and non-coordinating NEt(4)(+) and PPh(4)(+) countercations are reported. In general, these compounds can be prepared from U(NR)(2)I(2)(THF)(x) (x = 2 and R = (t)Bu, Ph; x = 3 and R = Me) upon addition of excess halide. In addition to providing stable coordination complexes with Cl(-), the [U(NMe)(2)](2+) cation also reacts with Br(-) to form stable [NEt(4)](2)[U(NMe)(2)Br(4)] complexes. These materials were used as a platform to compare electronic structure and bonding in [U(NR)(2)](2+) with [UO(2)](2+). Specifically, Cl K-edge X-ray absorption spectroscopy (XAS) and both ground-state and time-dependent hybrid density functional theory (DFT and TDDFT) were used to probe U-Cl bonding interactions in [PPh(4)](2)[U(N(t)Bu)(2)Cl(4)] and [PPh(4)](2)[UO(2)Cl(4)]. The DFT and XAS results show the total amount of Cl 3p character mixed with the U 5f orbitals was roughly 7-10% per U-Cl bond for both compounds, which shows that moving from oxo to imido has little effect on orbital mixing between the U 5f and equatorial Cl 3p orbitals. The results are presented in the context of recent Cl K-edge XAS and DFT studies on other hexavalent uranium chloride systems with fewer oxo or imido ligands.

  17. Image stack alignment in full-field X-ray absorption spectroscopy using SIFT_PyOCL.

    PubMed

    Paleo, Pierre; Pouyet, Emeline; Kieffer, Jérôme

    2014-03-01

    Full-field X-ray absorption spectroscopy experiments allow the acquisition of millions of spectra within minutes. However, the construction of the hyperspectral image requires an image alignment procedure with sub-pixel precision. While the image correlation algorithm has originally been used for image re-alignment using translations, the Scale Invariant Feature Transform (SIFT) algorithm (which is by design robust versus rotation, illumination change, translation and scaling) presents an additional advantage: the alignment can be limited to a region of interest of any arbitrary shape. In this context, a Python module, named SIFT_PyOCL, has been developed. It implements a parallel version of the SIFT algorithm in OpenCL, providing high-speed image registration and alignment both on processors and graphics cards. The performance of the algorithm allows online processing of large datasets.

  18. Highly sensitive transient absorption imaging of graphene and graphene oxide in living cells and circulating blood.

    PubMed

    Li, Junjie; Zhang, Weixia; Chung, Ting-Fung; Slipchenko, Mikhail N; Chen, Yong P; Cheng, Ji-Xin; Yang, Chen

    2015-07-23

    We report a transient absorption (TA) imaging method for fast visualization and quantitative layer analysis of graphene and GO. Forward and backward imaging of graphene on various substrates under ambient condition was imaged with a speed of 2 μs per pixel. The TA intensity linearly increased with the layer number of graphene. Real-time TA imaging of GO in vitro with capability of quantitative analysis of intracellular concentration and ex vivo in circulating blood were demonstrated. These results suggest that TA microscopy is a valid tool for the study of graphene based materials.

  19. Percutaneous Tricuspid Valve Regurgitation Repair With the MitraClip Device Using an Edge-to-Edge Bicuspidization Technique.

    PubMed

    Gafoor, Sameer; Petrescu, O Madalina; Lehr, Eric J; Puls, Charles; Zhang, Ming; Petersen, John L; Olsen, John V; Penev, Irina; Agrawal, Mayank; Sharma, Rahul; Barnhart, Glenn

    2017-03-01

    Patients who present with both severe mitral and tricuspid regurgitation who are symptomatic despite optimal medical therapy and at prohibitive risk for surgery pose a significant therapeutic challenge. The MitraClip device (Abbott Vascular) is approved for percutaneous mitral valve repair in high-risk and non-operative patients, and has also been used for tricuspid valve repair. Imaging support for percutaneous edge-to-edge tricuspid valve repair has not been reported and is a vital part of the procedure. Here, we present a periprocedural imaging strategy for percutaneous tricuspid valve repair with the MitraClip device using a bicuspidization technique.

  20. Bayes-Turchin analysis of x-ray absorption data above the Fe L{sub 2,3}-edges

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Rossner, H. H.; Schmitz, D.; Imperia, P.

    2006-10-01

    Extended x-ray absorption fine structure (EXAFS) data and magnetic EXAFS (MEXAFS) data were measured at two temperatures (180 and 296 K) in the energy region of the overlapping L-edges of bcc Fe grown on a V(110) crystal surface. In combination with a Bayes-Turchin data analysis procedure these measurements enable the exploration of local crystallographic and magnetic structures. The analysis determined the atomic-like background together with the EXAFS parameters which consisted of ten shell radii, the Debye-Waller parameters, separated into structural and vibrational components, and the third cumulant of the first scattering path. The vibrational components for 97 different scattering pathsmore » were determined by a two parameter force-field model using a priori values adjusted to Born-von Karman parameters of inelastic neutron scattering data. The investigations of the system Fe/V(110) demonstrate that the simultaneous fitting of atomic background parameters and EXAFS parameters can be performed reliably. Using the L{sub 2}- and L{sub 3}-components extracted from the EXAFS analysis and the rigid-band model, the MEXAFS oscillations can only be described when the sign of the exchange energy is changed compared to the predictions of the Hedin Lundquist exchange and correlation functional.« less

  1. Predicting Near Edge X-ray Absorption Spectra with the Spin-Free Exact-Two-Component Hamiltonian and Orthogonality Constrained Density Functional Theory.

    PubMed

    Verma, Prakash; Derricotte, Wallace D; Evangelista, Francesco A

    2016-01-12

    Orthogonality constrained density functional theory (OCDFT) provides near-edge X-ray absorption (NEXAS) spectra of first-row elements within one electronvolt from experimental values. However, with increasing atomic number, scalar relativistic effects become the dominant source of error in a nonrelativistic OCDFT treatment of core-valence excitations. In this work we report a novel implementation of the spin-free exact-two-component (X2C) one-electron treatment of scalar relativistic effects and its combination with a recently developed OCDFT approach to compute a manifold of core-valence excited states. The inclusion of scalar relativistic effects in OCDFT reduces the mean absolute error of second-row elements core-valence excitations from 10.3 to 2.3 eV. For all the excitations considered, the results from X2C calculations are also found to be in excellent agreement with those from low-order spin-free Douglas-Kroll-Hess relativistic Hamiltonians. The X2C-OCDFT NEXAS spectra of three organotitanium complexes (TiCl4, TiCpCl3, TiCp2Cl2) are in very good agreement with unshifted experimental results and show a maximum absolute error of 5-6 eV. In addition, a decomposition of the total transition dipole moment into partial atomic contributions is proposed and applied to analyze the nature of the Ti pre-edge transitions in the three organotitanium complexes.

  2. X-ray absorption spectroscopy investigations on oxidized Ni/Au contacts to p-GaN.

    PubMed

    Jan, J C; Asokan, K; Chiou, J W; Pong, W F; Tseng, P K; Chen, L C; Chen, F R; Lee, J F; Wu, J S; Lin, H J; Chen, C T

    2001-03-01

    X-ray absorption spectroscopy was used to investigate the electronic structure of as-deposited and oxidized Ni/Au contacts to p-GaN and to elucidate the mechanism responsible for low impedance. X-ray absorption near edge spectra of Ni K- and L3,2-edges clearly indicate formation of NiO on the sample surface after annealing. The reason for low impedance may be attributed to increase in hole concentration and existence of p-NiO layer on the surface.

  3. Invited Review Article: Imaging techniques for harmonic and multiphoton absorption fluorescence microscopy

    PubMed Central

    Carriles, Ramón; Schafer, Dawn N.; Sheetz, Kraig E.; Field, Jeffrey J.; Cisek, Richard; Barzda, Virginijus; Sylvester, Anne W.; Squier, Jeffrey A.

    2009-01-01

    We review the current state of multiphoton microscopy. In particular, the requirements and limitations associated with high-speed multiphoton imaging are considered. A description of the different scanning technologies such as line scan, multifoci approaches, multidepth microscopy, and novel detection techniques is given. The main nonlinear optical contrast mechanisms employed in microscopy are reviewed, namely, multiphoton excitation fluorescence, second harmonic generation, and third harmonic generation. Techniques for optimizing these nonlinear mechanisms through a careful measurement of the spatial and temporal characteristics of the focal volume are discussed, and a brief summary of photobleaching effects is provided. Finally, we consider three new applications of multiphoton microscopy: nonlinear imaging in microfluidics as applied to chemical analysis and the use of two-photon absorption and self-phase modulation as contrast mechanisms applied to imaging problems in the medical sciences. PMID:19725639

  4. The red edge in arid region vegetation: 340-1060 nm spectra

    NASA Technical Reports Server (NTRS)

    Ray, Terrill W.; Murray, Bruce C.; Chehbouni, A.; Njoku, Eni

    1993-01-01

    The remote sensing study of vegetated regions of the world has typically been focused on the use of broad-band vegetation indices such as NDVI. Various modifications of these indices have been developed in attempts to minimize the effect of soil background, e.g., SAVI, or to reduce the effect of the atmosphere, e.g., ARVI. Most of these indices depend on the so-called 'red edge,' the sharp transition between the strong absorption of chlorophyll pigment in visible wavelengths and the strong scattering in the near-infrared from the cellular structure of leaves. These broadband indices tend to become highly inaccurate as the green canopy cover becomes sparse. The advent of high spectral resolution remote sensing instrument such as the Airborne Visible and Infrared Imaging Spectrometer (AVIRIS) has allowed the detection of narrow spectral features in vegetation and there are reports of detection of the red edge even for pixels with very low levels of green vegetation cover by Vane et al. and Elvidge et al., and to characterize algal biomass in coastal areas. Spectral mixing approaches similar to those of Smith et al. can be extended into the high spectral resolution domain allowing for the analysis of more endmembers, and potentially, discrimination between material with narrow spectral differences. Vegetation in arid regions tends to be sparse, often with small leaves such as the creosote bush. Many types of arid region vegetation spend much of the year with their leaves in a senescent state, i.e., yellow, with lowered chlorophyll pigmentation. The sparseness of the leaves of many arid region plants has the dual effect of lowering the green leaf area which can be observed and of allowing more of the sub-shrub soil to be visible which further complicates the spectrum of a region covered with arid region vegetation. Elvidge examined the spectral characteristics of dry plant materials showing significant differences in the region of the red edge and the diagnostic ligno

  5. On the Electronic Structure of Cu Chlorophyllin and Its Breakdown Products: A Carbon K-Edge X-ray Absorption Spectroscopy Study.

    PubMed

    Witte, Katharina; Mantouvalou, Ioanna; Sánchez-de-Armas, Rocío; Lokstein, Heiko; Lebendig-Kuhla, Janina; Jonas, Adrian; Roth, Friedrich; Kanngießer, Birgit; Stiel, Holger

    2018-02-15

    Using near-edge X-ray absorption fine structure (NEXAFS) spectroscopy, the carbon backbone of sodium copper chlorophyllin (SCC), a widely used chlorophyll derivative, and its breakdown products are analyzed to elucidate their electronic structure and physicochemical properties. Using various sample preparation methods and complementary spectroscopic methods (including UV/Vis, X-ray photoelectron spectroscopy), a comprehensive insight into the SCC breakdown process is presented. The experimental results are supported by density functional theory calculations, allowing a detailed assignment of characteristic NEXAFS features to specific C bonds. SCC can be seen as a model system for the large group of porphyrins; thus, this work provides a novel and detailed description of the electronic structure of the carbon backbone of those molecules and their breakdown products. The achieved results also promise prospective optical pump/X-ray probe investigations of dynamic processes in chlorophyll-containing photosynthetic complexes to be analyzed more precisely.

  6. SR high-speed K-edge subtraction angiography in the small animal (abstract)

    NASA Astrophysics Data System (ADS)

    Takeda, T.; Akisada, M.; Nakajima, T.; Anno, I.; Ueda, K.; Umetani, K.; Yamaguchi, C.

    1989-07-01

    To assess the ability of the high-speed K-edge energy subtraction system which was made at beamline 8C of Photon Factory, Tsukuba, we performed an animal experiment. Rabbits were used for the intravenous K-edge subtraction angiography. In this paper, the actual images of the artery obtained by this system, are demonstrated. The high-speed K-edge subtraction system consisted of movable silicon (111) monocrystals, II-ITV, and digital memory system. Image processing was performed by 68000-IP computer. The monochromatic x-ray beam size was 50×60 mm. Photon energy above and below iodine K edge was changed within 16 ms and 32 frames of images were obtained sequentially. The rabbits were anaesthetized by phenobarbital and a 5F catheter was inserted into inferior vena cava via the femoral vein. 1.5 ml/kg of contrast material (Conlaxin H) was injected at the rate of 0.5 ml/kg/s. TV images were obtained 3 s after the starting point of injection. By using this system, the clear K-edge subtracted images were obtained sequentially as a conventional DSA system. The quality of the images were better than that obtained by DSA. The dynamical blood flow was analyzed, and the best arterial image could be selected from the sequential images. The structures of aortic arch, common carotid arteries, right subclavian artery, and internal thoracic artery were obtained at the chest. Both common carotid arteries and vertebral arteries were recorded at the neck. The diameter of about 0.3-0.4 mm artery could be clearly revealed. The high-speed K-edge subtraction system demonstrates the very sharp arterial images clearly and dynamically.

  7. Intelligent identification of remnant ridge edges in region west of Yongxing Island, South China Sea

    NASA Astrophysics Data System (ADS)

    Wang, Weiwei; Guo, Jing; Cai, Guanqiang; Wang, Dawei

    2018-02-01

    Edge detection enables identification of geomorphologic unit boundaries and thus assists with geomorphical mapping. In this paper, an intelligent edge identification method is proposed and image processing techniques are applied to multi-beam bathymetry data. To accomplish this, a color image is generated by the bathymetry, and a weighted method is used to convert the color image to a gray image. As the quality of the image has a significant influence on edge detection, different filter methods are applied to the gray image for de-noising. The peak signal-to-noise ratio and mean square error are calculated to evaluate which filter method is most appropriate for depth image filtering and the edge is subsequently detected using an image binarization method. Traditional image binarization methods cannot manage the complicated uneven seafloor, and therefore a binarization method is proposed that is based on the difference between image pixel values; the appropriate threshold for image binarization is estimated according to the probability distribution of pixel value differences between two adjacent pixels in horizontal and vertical directions, respectively. Finally, an eight-neighborhood frame is adopted to thin the binary image, connect the intermittent edge, and implement contour extraction. Experimental results show that the method described here can recognize the main boundaries of geomorphologic units. In addition, the proposed automatic edge identification method avoids use of subjective judgment, and reduces time and labor costs.

  8. 3D elemental sensitive imaging using transmission X-ray microscopy.

    PubMed

    Liu, Yijin; Meirer, Florian; Wang, Junyue; Requena, Guillermo; Williams, Phillip; Nelson, Johanna; Mehta, Apurva; Andrews, Joy C; Pianetta, Piero

    2012-09-01

    Determination of the heterogeneous distribution of metals in alloy/battery/catalyst and biological materials is critical to fully characterize and/or evaluate the functionality of the materials. Using synchrotron-based transmission x-ray microscopy (TXM), it is now feasible to perform nanoscale-resolution imaging over a wide X-ray energy range covering the absorption edges of many elements; combining elemental sensitive imaging with determination of sample morphology. We present an efficient and reliable methodology to perform 3D elemental sensitive imaging with excellent sample penetration (tens of microns) using hard X-ray TXM. A sample of an Al-Si piston alloy is used to demonstrate the capability of the proposed method.

  9. Highly specific spectroscopic photoacoustic molecular imaging of dynamic optical absorption shifts of an antibody-ICG contrast agent (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Wilson, Katheryne E.; Bachawal, Sunitha; Abou-Elkacem, Lotfi; Jensen, Kristen C.; Machtaler, Steven; Tian, Lu; Willmann, Juergen K.

    2017-03-01

    Improved techniques for breast cancer screening are critically needed as current methods lack diagnostic accuracy. Using spectroscopic photoacoustic (sPA) molecular imaging with a priori knowledge of optical absorption spectra allows suppression of endogenous background signal, increasing the overall sensitivity and specificity of the modality to exogenous contrast agents. Here, sPA imaging was used to monitor antibody-indocyanine green (ICG) conjugates as they undergo optical absorption spectrum shifts after cellular endocytosis and degradation to allow differentiation between normal murine mammary glands from breast cancer by enhancing molecular imaging signal from target (B7-H3)-bound antibody-ICG. First, B7-H3 was shown to have highly specific (AUC of 0.93) expression on both vascular endothelium and tumor stroma in malignant lesions through quantitative immunohistochemical staining of B7-H3 on 279 human samples (normal (n=53), benign lesions (11 subtypes, n=182), breast cancers (4 subtypes, n=97)), making B7-H3 a promising target for sPA imaging. Second, absorption spectra of intracellular and degraded B7-H3-ICG and Isotype control (Iso-ICG) were characterized through in vitro and in vivo experiments. Finally, a transgenic murine breast cancer model (FVB/N-Tg(MMTVPyMT)634Mul) was imaged, and sPA imaging in found a 3.01 (IQR 2.63, 3.38, P<0.001) fold increase in molecular B7-H3-ICG signal in tumors (n=80) compared to control conditions (B7-H3-ICG in tumor negative animals (n=60), Iso-ICG (n=30), blocking B7-H3+B7-H3-ICG (n=20), and free ICG (n=20)) despite significant tumor accumulation of Iso-ICG, confirmed through ex vivo histology. Overall, leveraging anti-B7-H3 antibody-ICG contrast agents, which have dynamic optical absorption spectra representative of molecular interactions, allows for highly specific sPA imaging of murine breast cancer.

  10. Edge detection techniques for iris recognition system

    NASA Astrophysics Data System (ADS)

    Tania, U. T.; Motakabber, S. M. A.; Ibrahimy, M. I.

    2013-12-01

    Nowadays security and authentication are the major parts of our daily life. Iris is one of the most reliable organ or part of human body which can be used for identification and authentication purpose. To develop an iris authentication algorithm for personal identification, this paper examines two edge detection techniques for iris recognition system. Between the Sobel and the Canny edge detection techniques, the experimental result shows that the Canny's technique has better ability to detect points in a digital image where image gray level changes even at slow rate.

  11. Information theoretic analysis of canny edge detection in visual communication

    NASA Astrophysics Data System (ADS)

    Jiang, Bo; Rahman, Zia-ur

    2011-06-01

    In general edge detection evaluation, the edge detectors are examined, analyzed, and compared either visually or with a metric for specific an application. This analysis is usually independent of the characteristics of the image-gathering, transmission and display processes that do impact the quality of the acquired image and thus, the resulting edge image. We propose a new information theoretic analysis of edge detection that unites the different components of the visual communication channel and assesses edge detection algorithms in an integrated manner based on Shannon's information theory. The edge detection algorithm here is considered to achieve high performance only if the information rate from the scene to the edge approaches the maximum possible. Thus, by setting initial conditions of the visual communication system as constant, different edge detection algorithms could be evaluated. This analysis is normally limited to linear shift-invariant filters so in order to examine the Canny edge operator in our proposed system, we need to estimate its "power spectral density" (PSD). Since the Canny operator is non-linear and shift variant, we perform the estimation for a set of different system environment conditions using simulations. In our paper we will first introduce the PSD of the Canny operator for a range of system parameters. Then, using the estimated PSD, we will assess the Canny operator using information theoretic analysis. The information-theoretic metric is also used to compare the performance of the Canny operator with other edge-detection operators. This also provides a simple tool for selecting appropriate edgedetection algorithms based on system parameters, and for adjusting their parameters to maximize information throughput.

  12. Masked-backlighter technique used to simultaneously image x-ray absorption and x-ray emission from an inertial confinement fusion plasma.

    PubMed

    Marshall, F J; Radha, P B

    2014-11-01

    A method to simultaneously image both the absorption and the self-emission of an imploding inertial confinement fusion plasma has been demonstrated on the OMEGA Laser System. The technique involves the use of a high-Z backlighter, half of which is covered with a low-Z material, and a high-speed x-ray framing camera aligned to capture images backlit by this masked backlighter. Two strips of the four-strip framing camera record images backlit by the high-Z portion of the backlighter, while the other two strips record images aligned with the low-Z portion of the backlighter. The emission from the low-Z material is effectively eliminated by a high-Z filter positioned in front of the framing camera, limiting the detected backlighter emission to that of the principal emission line of the high-Z material. As a result, half of the images are of self-emission from the plasma and the other half are of self-emission plus the backlighter. The advantage of this technique is that the self-emission simultaneous with backlighter absorption is independently measured from a nearby direction. The absorption occurs only in the high-Z backlit frames and is either spatially separated from the emission or the self-emission is suppressed by filtering, or by using a backlighter much brighter than the self-emission, or by subtraction. The masked-backlighter technique has been used on the OMEGA Laser System to simultaneously measure the emission profiles and the absorption profiles of polar-driven implosions.

  13. In-Line Phase-Contrast X-ray Imaging and Tomography for Materials Science

    PubMed Central

    Mayo, Sheridan C.; Stevenson, Andrew W.; Wilkins, Stephen W.

    2012-01-01

    X-ray phase-contrast imaging and tomography make use of the refraction of X-rays by the sample in image formation. This provides considerable additional information in the image compared to conventional X-ray imaging methods, which rely solely on X-ray absorption by the sample. Phase-contrast imaging highlights edges and internal boundaries of a sample and is thus complementary to absorption contrast, which is more sensitive to the bulk of the sample. Phase-contrast can also be used to image low-density materials, which do not absorb X-rays sufficiently to form a conventional X-ray image. In the context of materials science, X-ray phase-contrast imaging and tomography have particular value in the 2D and 3D characterization of low-density materials, the detection of cracks and voids and the analysis of composites and multiphase materials where the different components have similar X-ray attenuation coefficients. Here we review the use of phase-contrast imaging and tomography for a wide variety of materials science characterization problems using both synchrotron and laboratory sources and further demonstrate the particular benefits of phase contrast in the laboratory setting with a series of case studies. PMID:28817018

  14. In-Line Phase-Contrast X-ray Imaging and Tomography for Materials Science.

    PubMed

    Mayo, Sheridan C; Stevenson, Andrew W; Wilkins, Stephen W

    2012-05-24

    X-ray phase-contrast imaging and tomography make use of the refraction of X-rays by the sample in image formation. This provides considerable additional information in the image compared to conventional X-ray imaging methods, which rely solely on X-ray absorption by the sample. Phase-contrast imaging highlights edges and internal boundaries of a sample and is thus complementary to absorption contrast, which is more sensitive to the bulk of the sample. Phase-contrast can also be used to image low-density materials, which do not absorb X-rays sufficiently to form a conventional X-ray image. In the context of materials science, X-ray phase-contrast imaging and tomography have particular value in the 2D and 3D characterization of low-density materials, the detection of cracks and voids and the analysis of composites and multiphase materials where the different components have similar X-ray attenuation coefficients. Here we review the use of phase-contrast imaging and tomography for a wide variety of materials science characterization problems using both synchrotron and laboratory sources and further demonstrate the particular benefits of phase contrast in the laboratory setting with a series of case studies.

  15. Imaging system design and image interpolation based on CMOS image sensor

    NASA Astrophysics Data System (ADS)

    Li, Yu-feng; Liang, Fei; Guo, Rui

    2009-11-01

    An image acquisition system is introduced, which consists of a color CMOS image sensor (OV9620), SRAM (CY62148), CPLD (EPM7128AE) and DSP (TMS320VC5509A). The CPLD implements the logic and timing control to the system. SRAM stores the image data, and DSP controls the image acquisition system through the SCCB (Omni Vision Serial Camera Control Bus). The timing sequence of the CMOS image sensor OV9620 is analyzed. The imaging part and the high speed image data memory unit are designed. The hardware and software design of the image acquisition and processing system is given. CMOS digital cameras use color filter arrays to sample different spectral components, such as red, green, and blue. At the location of each pixel only one color sample is taken, and the other colors must be interpolated from neighboring samples. We use the edge-oriented adaptive interpolation algorithm for the edge pixels and bilinear interpolation algorithm for the non-edge pixels to improve the visual quality of the interpolated images. This method can get high processing speed, decrease the computational complexity, and effectively preserve the image edges.

  16. Localized modes in optics of photonic liquid crystals with local anisotropy of absorption

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Belyakov, V. A., E-mail: bel1937@mail.ru, E-mail: bel@landau.ac.ru; Semenov, S. V.

    2016-05-15

    The localized optical modes in spiral photonic liquid crystals are theoretically studied for the certainty at the example of chiral liquid crystals (CLCs) for the case of CLC with an anisotropic local absorption. The model adopted here (absence of dielectric interfaces in the structures under investigation) makes it possible to get rid of mixing of polarizations on the surfaces of the CLC layer and of the defect structure and to reduce the corresponding equations to only the equations for light with polarization diffracting in the CLC. The dispersion equations determining connection of the edge mode (EM) and defect mode (DM)more » frequencies with the CLC layer parameters (anisotropy of local absorption, CLC order parameter) and other parameters of the DMS are obtained. Analytic expressions for the transmission and reflection coefficients of CLC layer and DMS for the case of CLC with an anisotropic local absorption are presented and analyzed. It is shown that the CLC layers with locally anisotropic absorption reduce the EM and DM lifetimes (and increase the lasing threshold) in the way different from the case of CLC with an isotropic local absorption. Due to the Borrmann effect revealing of which is different at the opposite stop-band edges in the case of CLC layers with an anisotropic local absorption the EM life-times for the EM frequencies at the opposite stop-bands edges may be significantly different. The options of experimental observations of the theoretically revealed phenomena are briefly discussed.« less

  17. Femtosecond time-resolved X-ray absorption spectroscopy of anatase TiO2 nanoparticles using XFEL

    PubMed Central

    Obara, Yuki; Ito, Hironori; Ito, Terumasa; Kurahashi, Naoya; Thürmer, Stephan; Tanaka, Hiroki; Katayama, Tetsuo; Togashi, Tadashi; Owada, Shigeki; Yamamoto, Yo-ichi; Karashima, Shutaro; Nishitani, Junichi; Yabashi, Makina; Suzuki, Toshinori; Misawa, Kazuhiko

    2017-01-01

    The charge-carrier dynamics of anatase TiO2 nanoparticles in an aqueous solution were studied by femtosecond time-resolved X-ray absorption spectroscopy using an X-ray free electron laser in combination with a synchronized ultraviolet femtosecond laser (268 nm). Using an arrival time monitor for the X-ray pulses, we obtained a temporal resolution of 170 fs. The transient X-ray absorption spectra revealed an ultrafast Ti K-edge shift and a subsequent growth of a pre-edge structure. The edge shift occurred in ca. 100 fs and is ascribed to reduction of Ti by localization of generated conduction band electrons into shallow traps of self-trapped polarons or deep traps at penta-coordinate Ti sites. Growth of the pre-edge feature and reduction of the above-edge peak intensity occur with similar time constants of 300–400 fs, which we assign to the structural distortion dynamics near the surface. PMID:28713842

  18. SU-E-I-76: Optimizing Imaging Parameters for a Novel Radiographic Imaging System for the Detection of Corrosion in Aluminum Aircraft Structures.

    PubMed

    Hammonds, J; Price, R; Donnelly, E; Pickens, D

    2012-06-01

    A laboratory-based phase-contrast radiography/tomosynthesis imaging system previously (Med. Phys. Vol. 38, 2353 May 2011) for improved detection of low-contrast soft-tissue masses was used to evaluate the sensitivity for detecting the presence of thin layers of corrosion on aluminum aircraft structures. The evaluation utilized a test object of aluminum (2.5 inch × 2.5 inch × 1/8 inch) on which different geometric patterns of 0.0038 inch thick anodized aluminum oxide was deposited. A circular area of radius 1 inch centered on the phantom's midpoint was milled to an approximate thickness of 0.022 inches. The x-ray source used for this investigation was a dual focal spot, tungsten anode x-ray tube. The focal used during the investigation has a nominal size of 0.010 mm. The active area of the imager is 17.1 cm × 23.9 cm (2016 × 2816 pixels) with a pixel pitch of 0.085 mm. X-ray tube voltages ranged from 20-40 kVp and source- to-object and object-to-image distances were varied from 20-100 cm. Performance of the phase-contrast mode was compared to conventional absorption-based radiography using contrast ratio and contrast-to-noise ratios (C/N). Phase-contrast performance was based on edge-enhancement index (EEI) and the edge-enhancement-to-noise (EE/N) ratio. for absorption-based radiography, the best C/N ratio was observed at the lowest kVp value (20 kVp). The optimum sampling angle for tomosynthesis was +/- 8 degrees. Comparing C/N to EE/N demonstrated the phase-contrast techniques improve the conspicuity of the oxide layer edges. This work provides the optimal parameters that a radiographic imaging system would need to differentiate the two different compounds of aluminum. Subcontractee from Positron Systems Inc. (Boise, Idaho) through United States Air Force grant (AF083-225). © 2012 American Association of Physicists in Medicine.

  19. Artifact suppression in electron paramagnetic resonance imaging of 14N- and 15N-labeled nitroxyl radicals with asymmetric absorption spectra

    NASA Astrophysics Data System (ADS)

    Takahashi, Wataru; Miyake, Yusuke; Hirata, Hiroshi

    2014-10-01

    This article describes an improved method for suppressing image artifacts in the visualization of 14N- and 15N-labeled nitroxyl radicals in a single image scan using electron paramagnetic resonance (EPR). The purpose of this work was to solve the problem of asymmetric EPR absorption spectra in spectral processing. A hybrid function of Gaussian and Lorentzian lineshapes was used to perform spectral line-fitting to successfully separate the two kinds of nitroxyl radicals. This approach can process the asymmetric EPR absorption spectra of the nitroxyl radicals being measured, and can suppress image artifacts due to spectral asymmetry. With this improved visualization method and a 750-MHz continuous-wave EPR imager, a temporal change in the distributions of a two-phase paraffin oil and water/glycerin solution system was visualized using lipophilic and hydrophilic nitroxyl radicals, i.e., 2-(14-carboxytetradecyl)-2-ethyl-4,4-dimethyl-3-oxazolidinyloxy (16-DOXYL stearic acid) and 4-hydroxyl-2,2,6,6-tetramethylpiperidine-d17-1-15N-1-oxyl (TEMPOL-d17-15N). The results of the two-phase separation experiment verified that reasonable artifact suppression could be achieved by the present method that deals with asymmetric absorption spectra in the EPR imaging of 14N- and 15N-labeled nitroxyl radicals.

  20. Highly sensitive transient absorption imaging of graphene and graphene oxide in living cells and circulating blood

    PubMed Central

    Li, Junjie; Zhang, Weixia; Chung, Ting-Fung; Slipchenko, Mikhail N.; Chen, Yong P.; Cheng, Ji-Xin; Yang, Chen

    2015-01-01

    We report a transient absorption (TA) imaging method for fast visualization and quantitative layer analysis of graphene and GO. Forward and backward imaging of graphene on various substrates under ambient condition was imaged with a speed of 2 μs per pixel. The TA intensity linearly increased with the layer number of graphene. Real-time TA imaging of GO in vitro with capability of quantitative analysis of intracellular concentration and ex vivo in circulating blood were demonstrated. These results suggest that TA microscopy is a valid tool for the study of graphene based materials. PMID:26202216

  1. HyperART: non-invasive quantification of leaf traits using hyperspectral absorption-reflectance-transmittance imaging.

    PubMed

    Bergsträsser, Sergej; Fanourakis, Dimitrios; Schmittgen, Simone; Cendrero-Mateo, Maria Pilar; Jansen, Marcus; Scharr, Hanno; Rascher, Uwe

    2015-01-01

    Combined assessment of leaf reflectance and transmittance is currently limited to spot (point) measurements. This study introduces a tailor-made hyperspectral absorption-reflectance-transmittance imaging (HyperART) system, yielding a non-invasive determination of both reflectance and transmittance of the whole leaf. We addressed its applicability for analysing plant traits, i.e. assessing Cercospora beticola disease severity or leaf chlorophyll content. To test the accuracy of the obtained data, these were compared with reflectance and transmittance measurements of selected leaves acquired by the point spectroradiometer ASD FieldSpec, equipped with the FluoWat device. The working principle of the HyperART system relies on the upward redirection of transmitted and reflected light (range of 400 to 2500 nm) of a plant sample towards two line scanners. By using both the reflectance and transmittance image, an image of leaf absorption can be calculated. The comparison with the dynamically high-resolution ASD FieldSpec data showed good correlation, underlying the accuracy of the HyperART system. Our experiments showed that variation in both leaf chlorophyll content of four different crop species, due to different fertilization regimes during growth, and fungal symptoms on sugar beet leaves could be accurately estimated and monitored. The use of leaf reflectance and transmittance, as well as their sum (by which the non-absorbed radiation is calculated) obtained by the HyperART system gave considerably improved results in classification of Cercospora leaf spot disease and determination of chlorophyll content. The HyperART system offers the possibility for non-invasive and accurate mapping of leaf transmittance and absorption, significantly expanding the applicability of reflectance, based on mapping spectroscopy, in plant sciences. Therefore, the HyperART system may be readily employed for non-invasive determination of the spatio-temporal dynamics of various plant

  2. A synthetic genetic edge detection program.

    PubMed

    Tabor, Jeffrey J; Salis, Howard M; Simpson, Zachary Booth; Chevalier, Aaron A; Levskaya, Anselm; Marcotte, Edward M; Voigt, Christopher A; Ellington, Andrew D

    2009-06-26

    Edge detection is a signal processing algorithm common in artificial intelligence and image recognition programs. We have constructed a genetically encoded edge detection algorithm that programs an isogenic community of E. coli to sense an image of light, communicate to identify the light-dark edges, and visually present the result of the computation. The algorithm is implemented using multiple genetic circuits. An engineered light sensor enables cells to distinguish between light and dark regions. In the dark, cells produce a diffusible chemical signal that diffuses into light regions. Genetic logic gates are used so that only cells that sense light and the diffusible signal produce a positive output. A mathematical model constructed from first principles and parameterized with experimental measurements of the component circuits predicts the performance of the complete program. Quantitatively accurate models will facilitate the engineering of more complex biological behaviors and inform bottom-up studies of natural genetic regulatory networks.

  3. A Synthetic Genetic Edge Detection Program

    PubMed Central

    Tabor, Jeffrey J.; Salis, Howard; Simpson, Zachary B.; Chevalier, Aaron A.; Levskaya, Anselm; Marcotte, Edward M.; Voigt, Christopher A.; Ellington, Andrew D.

    2009-01-01

    Summary Edge detection is a signal processing algorithm common in artificial intelligence and image recognition programs. We have constructed a genetically encoded edge detection algorithm that programs an isogenic community of E.coli to sense an image of light, communicate to identify the light-dark edges, and visually present the result of the computation. The algorithm is implemented using multiple genetic circuits. An engineered light sensor enables cells to distinguish between light and dark regions. In the dark, cells produce a diffusible chemical signal that diffuses into light regions. Genetic logic gates are used so that only cells that sense light and the diffusible signal produce a positive output. A mathematical model constructed from first principles and parameterized with experimental measurements of the component circuits predicts the performance of the complete program. Quantitatively accurate models will facilitate the engineering of more complex biological behaviors and inform bottom-up studies of natural genetic regulatory networks. PMID:19563759

  4. Parametric measurements of the effect of in-duct orifice edge shape on its noise damping performance

    NASA Astrophysics Data System (ADS)

    Ji, Chenzhen; Zhao, Dan; Han, Nuomin; Li, Jing

    2016-12-01

    Acoustic liners perforated with thousands of millimeter-size orifices are widely used in aero-engines and gas turbine engines as an effective noise damper. In this work, experimental investigations of the acoustic damping effect of in-duct perforated orifices are performed on a cold-flow pipe. A mean flow (also known as bias flow) is applied and its flow rate is variable. Emphasis is placed on the effect of the orifice edge shape. For this, 16 in-duct orifices with different edge shapes and porosities are designed and manufactured by using 3D printing technology and conventional laser cutting technique. The damping effect of these in-duct orifices is characterized by using power absorption coefficient Δ and reflection coefficient χ from 100 to 1000 Hz. The performances of these orifices are found to be either improved or deteriorated, depending on (1) edge shape, (2) the ratio T/d of orifice thickness to its diameter, (3) the bias flow Mach number, (4) downstream pipe length Ld and (5) porosity η via varying either the number N or surface area Ao of the orifices. In addition, modifying orifice edge does not lead to an increase of power absorption at lower frequency (⩽ 700 Hz). However, as the frequency is increased, the orifice with square (S-type) edge is found to be associated with 10 percent more power absorption. It is interesting to find that T/d over the tested range (≤ 0.5) has little influence on its damping capacity. However, the mean bias flow Mach number Ma and porosity η are shown to play critical roles on determining the noise damping performance of these orifices. Maximum power absorption Δmax is found to occur at Ma ≈ 0.018, while the optimum porosity corresponding to Δmax is approximately 7 percent. The present parametric measurements shed light on the roles of orifice edge shape, porosity and mean flow on its noise damping capacity, and facilitate the design of effective perforated liners.

  5. On the Structure of the Iron K-Edge

    NASA Technical Reports Server (NTRS)

    Palmeri, P.; Mendoza, C.; Kallman, T. R.; Bautista, M. A.; White, Nicholas E. (Technical Monitor)

    2002-01-01

    It is shown that the commonly held view of a sharp Fe K edge must be modified if the decay pathways of the series of resonances converging to the K thresholds are adequately taken into account. These resonances display damped Lorentzian profiles of nearly constant widths that are smeared to impose continuity across the threshold. By modeling the effects of K damping on opacities, it is found that the broadening of the K edge grows with the ionization level of the plasma, and the appearance at high ionization of a localized absorption feature at 7.2 keV is identified as the Kbeta unresolved transition array.

  6. Magnesium K-edge XANES spectroscopy of geological standards.

    PubMed

    Yoshimura, Toshihiro; Tamenori, Yusuke; Iwasaki, Nozomu; Hasegawa, Hiroshi; Suzuki, Atsushi; Kawahata, Hodaka

    2013-09-01

    Magnesium K-edge X-ray absorption near-edge structure (XANES) spectra have been investigated to develop a systematic understanding of a suite of Mg-bearing geological materials such as silicate and carbonate minerals, sediments, rocks and chemical reagents. For the model compounds the Mg XANES was found to vary widely between compounds and to provide a fingerprint for the form of Mg involved in geologic materials. The energy positions and resonance features obtained from these spectra can be used to specify the dominant molecular host site of Mg, thus shedding light on Mg partitioning and isotope fractionation in geologic materials and providing a valuable complement to existing knowledge of Mg geochemistry.

  7. Intergalactic Helium Absorption toward High-Redshift Quasars

    NASA Technical Reports Server (NTRS)

    Giroux, Mark L.; Fardal, Mark A.; Shull, J. Michael

    1995-01-01

    The recent Hubble Space Telescope (HST) observations of the z(q) = 3.286 quasar Q0302-003 (Jakobsen et at. 1994) and the z(q) = 3.185 quasar Q1935-67 by Tytler (1995) show absorption edges at the redshifted wavelength of He II 304 A. A key goal is to distinguish between contributions from discrete Ly-alpha forest clouds and a smoothly distributed intergalactic medium (IGM). We model the contributions from each of these sources of He II absorption, including the distribution of line Doppler widths and column densities, the 'He II proximity effect' from the quasar, and a self-consistent derivation of the He II opacity of the universe as a function of the spectrum of ionizing sources, with the assumption that both the clouds and the IGM are photoionized. The He II edge can be fully accounted for by He II line blanketing for reasonable distributions of line widths and column densities in the Ly-alpha forest, provided that the ionizing sources have spectral index alpha(s) greater than 1.5, and any He II proximity effect is neglected. Even with some contribution from a diffuse IGM, it is difficult to account for the edge observed by Jakobsen et al. (1994) with a 'hard' source spectrum (alpha(s) less than 1.3). The proximity effect modifies the relative contributions of the clouds and IGM to tau(He II) near the quasar (z approx. less than z(q)) and markedly increases the amount of He II absorption required. This implies, for example, that to account for the He II edge with line blanketing alone, the minimum spectral index alpha(s) must be increased from 1.5 to 1.9. We demonstrate the need for higher resolution observations that characterize the change in transmission as z approaches z(q) and resolve line-free gaps in the continuum. We set limits on the density of the diffuse IGM and suggest that the IGM and Ly-alpha clouds are likely to be a significant repository for dark baryons.

  8. X-ray absorption spectral studies of copper (II) mixed ligand complexes

    NASA Astrophysics Data System (ADS)

    Soni, B.; Dar, Davood Ah; Shrivastava, B. D.; Prasad, J.; Srivastava, K.

    2014-09-01

    X-ray absorption spectra at the K-edge of copper have been studied in two copper mixed ligand complexes, one having tetramethyethylenediamine (tmen) and the other having tetraethyethylenediamine (teen) as one of the ligands. The spectra have been recorded at BL-8 dispersive extended X-ray absorption fine structure (EXAFS) beamline at the 2.5 GeV INDUS- 2 synchrotron, RRCAT, Indore, India. The data obtained has been processed using the data analysis program Athena. The energy of the K-absorption edge, chemical shift, edge-width and shift of the principal absorption maximum in the complexes have been determined and discussed. The values of these parameters have been found to be approximately the same in both the complexes indicating that the two complexes possess similar chemical environment around the copper metal atom. The chemical shift has been utilized to estimate effective nuclear charge on the absorbing atom. The normalized EXAFS spectra have been Fourier transformed. The position of the first peak in the Fourier transform gives the value of first shell bond length, which is shorter than the actual bond length because of energy dependence of the phase factors in the sine function of the EXAFS equation. This distance is thus the phase- uncorrected bond length. Bond length has also been determined by Levy's, Lytle's and Lytle, Sayers and Stern's (LSS) methods. The results obtained from LSS and the Fourier transformation methods are comparable with each other, since both are phase uncorrected bond lengths.

  9. Edge Probability and Pixel Relativity-Based Speckle Reducing Anisotropic Diffusion.

    PubMed

    Mishra, Deepak; Chaudhury, Santanu; Sarkar, Mukul; Soin, Arvinder Singh; Sharma, Vivek

    2018-02-01

    Anisotropic diffusion filters are one of the best choices for speckle reduction in the ultrasound images. These filters control the diffusion flux flow using local image statistics and provide the desired speckle suppression. However, inefficient use of edge characteristics results in either oversmooth image or an image containing misinterpreted spurious edges. As a result, the diagnostic quality of the images becomes a concern. To alleviate such problems, a novel anisotropic diffusion-based speckle reducing filter is proposed in this paper. A probability density function of the edges along with pixel relativity information is used to control the diffusion flux flow. The probability density function helps in removing the spurious edges and the pixel relativity reduces the oversmoothing effects. Furthermore, the filtering is performed in superpixel domain to reduce the execution time, wherein a minimum of 15% of the total number of image pixels can be used. For performance evaluation, 31 frames of three synthetic images and 40 real ultrasound images are used. In most of the experiments, the proposed filter shows a better performance as compared to the state-of-the-art filters in terms of the speckle region's signal-to-noise ratio and mean square error. It also shows a comparative performance for figure of merit and structural similarity measure index. Furthermore, in the subjective evaluation, performed by the expert radiologists, the proposed filter's outputs are preferred for the improved contrast and sharpness of the object boundaries. Hence, the proposed filtering framework is suitable to reduce the unwanted speckle and improve the quality of the ultrasound images.

  10. High-Speed Edge-Detecting Line Scan Smart Camera

    NASA Technical Reports Server (NTRS)

    Prokop, Norman F.

    2012-01-01

    A high-speed edge-detecting line scan smart camera was developed. The camera is designed to operate as a component in a NASA Glenn Research Center developed inlet shock detection system. The inlet shock is detected by projecting a laser sheet through the airflow. The shock within the airflow is the densest part and refracts the laser sheet the most in its vicinity, leaving a dark spot or shadowgraph. These spots show up as a dip or negative peak within the pixel intensity profile of an image of the projected laser sheet. The smart camera acquires and processes in real-time the linear image containing the shock shadowgraph and outputting the shock location. Previously a high-speed camera and personal computer would perform the image capture and processing to determine the shock location. This innovation consists of a linear image sensor, analog signal processing circuit, and a digital circuit that provides a numerical digital output of the shock or negative edge location. The smart camera is capable of capturing and processing linear images at over 1,000 frames per second. The edges are identified as numeric pixel values within the linear array of pixels, and the edge location information can be sent out from the circuit in a variety of ways, such as by using a microcontroller and onboard or external digital interface to include serial data such as RS-232/485, USB, Ethernet, or CAN BUS; parallel digital data; or an analog signal. The smart camera system can be integrated into a small package with a relatively small number of parts, reducing size and increasing reliability over the previous imaging system..

  11. Imaging Plasmon Hybridization of Fano Resonances via Hot-Electron-Mediated Absorption Mapping.

    PubMed

    Simoncelli, Sabrina; Li, Yi; Cortés, Emiliano; Maier, Stefan A

    2018-06-13

    The inhibition of radiative losses in dark plasmon modes allows storing electromagnetic energy more efficiently than in far-field excitable bright-plasmon modes. As such, processes benefiting from the enhanced absorption of light in plasmonic materials could also take profit of dark plasmon modes to boost and control nanoscale energy collection, storage, and transfer. We experimentally probe this process by imaging with nanoscale precision the hot-electron driven desorption of thiolated molecules from the surface of gold Fano nanostructures, investigating the effect of wavelength and polarization of the incident light. Spatially resolved absorption maps allow us to show the contribution of each element of the nanoantenna in the hot-electron driven process and their interplay in exciting a dark plasmon mode. Plasmon-mode engineering allows control of nanoscale reactivity and offers a route to further enhance and manipulate hot-electron driven chemical reactions and energy-conversion and transfer at the nanoscale.

  12. Optical Kerr effect and two-photon absorption in monolayer black phosphorus

    NASA Astrophysics Data System (ADS)

    Margulis, Vl A.; Muryumin, E. E.; Gaiduk, E. A.

    2018-05-01

    A theoretical treatment of nonlinear refraction and two-photon absorption is presented for a novel two-dimensional material, monolayer black phosphorus (or phosphorene), irradiated by a normally incident and linearly polarized coherent laser beam of frequency ω. It is found that both the nonlinear refractive index n 2(ω) and the two-photon absorption coefficient α 2(ω) of phosphorene depend upon the polarization of the radiation field relative to phosphorene’s crystallographic axes. For the two principal polarization directions considered—viz, the armchair ({ \\mathcal A }{ \\mathcal C }) and zigzag ({ \\mathcal Z }{ \\mathcal Z }), the calculated values of n 2 and α 2 are distinguished by the order of their magnitude, with the n 2 and α 2 values being greater for the { \\mathcal A }{ \\mathcal C } direction. Furthermore, for almost all the incident photon energies below the fundamental absorption edge, except its neighborhood, the signs of n 2 as well as α 2 for the { \\mathcal A }{ \\mathcal C } and { \\mathcal Z }{ \\mathcal Z } polarization directions are opposed to each other. Also, for both the directions, the change of sign of n 2 is predicted to occur in the way between the two-photon absorption edge and the fundamental absorption edge, as well as in the near vicinity of the latter, where the Kerr nonlinearity has a pronounced resonant character and the magnitude of n 2 for the { \\mathcal A }{ \\mathcal C } and { \\mathcal Z }{ \\mathcal Z } polarization directions reaches its largest positive values of the order of 10‑9 and 10‑10 cm2 W‑1, respectively. The implications of the findings for practical all-optical switching applications are discussed.

  13. Optical Absorption in Degenerately Doped Semiconductors: Mott Transition or Mahan Excitons?

    NASA Astrophysics Data System (ADS)

    Schleife, André; Rödl, Claudia; Fuchs, Frank; Hannewald, Karsten; Bechstedt, Friedhelm

    2011-12-01

    Electron doping turns semiconductors conductive even when they have wide fundamental band gaps. The degenerate electron gas in the lowest conduction-band states, e.g., of a transparent conducting oxide, drastically modifies the Coulomb interaction between the electrons and, hence, the optical properties close to the absorption edge. We describe these effects by developing an ab initio technique which captures also the Pauli blocking and the Fermi-edge singularity at the optical-absorption onset, that occur in addition to quasiparticle and excitonic effects. We answer the question whether free carriers induce an excitonic Mott transition or trigger the evolution of Wannier-Mott excitons into Mahan excitons. The prototypical n-type zinc oxide is studied as an example.

  14. Mass Spectrometry Imaging proves differential absorption profiles of well-characterised permeability markers along the crypt-villus axis.

    PubMed

    Nilsson, Anna; Peric, Alexandra; Strimfors, Marie; Goodwin, Richard J A; Hayes, Martin A; Andrén, Per E; Hilgendorf, Constanze

    2017-07-25

    Knowledge about the region-specific absorption profiles from the gastrointestinal tract of orally administered drugs is a critical factor guiding dosage form selection in drug development. We have used a novel approach to study three well-characterized permeability and absorption marker drugs in the intestine. Propranolol and metoprolol (highly permeable compounds) and atenolol (low-moderate permeability compound) were orally co-administered to rats. The site of drug absorption was revealed by high spatial resolution matrix-assisted laser desorption ionization mass spectrometry imaging (MALDI-MSI) and complemented by quantitative measurement of drug concentration in tissue homogenates. MALDI-MSI identified endogenous molecular markers that illustrated the villi structures and confirmed the different absorption sites assigned to histological landmarks for the three drugs. Propranolol and metoprolol showed a rapid absorption and shorter transit distance in contrast to atenolol, which was absorbed more slowly from more distal sites. This study provides novel insights into site specific absorption for each of the compounds along the crypt-villus axis, as well as confirming a proximal-distal absorption gradient along the intestine. The combined analytical approach allowed the quantification and spatial resolution of drug distribution in the intestine and provided experimental evidence for the suggested absorption behaviour of low and highly permeable compounds.

  15. The edge detection method of the infrared imagery of the laser spot

    NASA Astrophysics Data System (ADS)

    Che, Jinxi; Zhang, Jinchun; Li, Zhongmin

    2016-01-01

    In the jamming effectiveness experiments, in which the thermal infrared imager was interfered by the CO2 Laser, in order to evaluate the jamming effect of the thermal infrared imager by the CO2 Laser, it was needed to analyses the obtained infrared imagery of laser spot. Because the laser spot pictures obtained from the thermal infrared imager are irregular, the edge detection is an important process. The image edge is one of the most basic characteristics of the image, and it contains most of the information of the image. Generally, because of the thermal balance effect, the partly temperature of objective is no quite difference; therefore the infrared imagery's ability of reflecting the local detail of object is obvious week. At the same time, when the information of heat distribution of the thermal imagery was combined with the basic information of target, such as the object size, the relative position of field of view, shape and outline, and so on, the information just has more value. Hence, it is an important step for making image processing to extract the objective edge of the infrared imagery. Meanwhile it is an important part of image processing procedure and it is the premise of many subsequent processing. So as to extract outline information of the target from the original thermal imagery, and overcome the disadvantage, such as the low image contrast of the image and serious noise interference, and so on, the edge of thermal imagery needs detecting and processing. The principles of the Roberts, Sobel, Prewitt and Canny operator were analyzed, and then they were used to making edge detection on the thermal imageries of laser spot, which were obtained from the jamming effect experiments of CO2 laser jamming the thermal infrared imager. On the basis of the detection result, their performances were compared. At the end, the characteristics of the operators were summarized, which provide reference for the choice of edge detection operators in thermal imagery

  16. Molybdenum L-Edge XAS Spectra of MoFe Nitrogenase

    PubMed Central

    Bjornsson, Ragnar; Delgado-Jaime, Mario U; Lima, Frederico A; Sippel, Daniel; Schlesier, Julia; Weyhermüller, Thomas; Einsle, Oliver; Neese, Frank; DeBeer, Serena

    2015-01-01

    A molybdenum L-edge X-ray absorption spectroscopy (XAS) study is presented for native and oxidized MoFe protein of nitrogenase as well as Mo-Fe model compounds. Recently collected data on MoFe protein (in oxidized and reduced forms) is compared to previously published Mo XAS data on the isolated FeMo cofactor in NMF solution and put in context of the recent Mo K-edge XAS study, which showed a MoIII assignment for the molybdenum atom in FeMoco. The L3-edge data are interpreted within a simple ligand-field model, from which a time-dependent density functional theory (TDDFT) approach is proposed as a way to provide further insights into the analysis of the molybdenum L3-edges. The calculated results reproduce well the relative spectral trends that are observed experimentally. Ultimately, these results give further support for the MoIII assignment in protein-bound FeMoco, as well as isolated FeMoco. PMID:26213424

  17. Charge and Spin-State Characterization of Cobalt Bis( o-dioxolene) Valence Tautomers Using Co Kβ X-ray Emission and L-Edge X-ray Absorption Spectroscopies

    DOE PAGES

    Liang, H. Winnie; Kroll, Thomas; Nordlund, Dennis; ...

    2016-12-30

    The valence tautomeric states of Co(phen)(3,5-DBQ) 2 and Co(tmeda)(3,5-DBQ) 2, where 3,5-DBQ is either the semiquinone (SQ –) or catecholate (Cat 2–) form of 3,5-di- tert-butyl-1,2-benzoquinone, have been examined by a series of cobalt-specific X-ray spectroscopies. In this work, we have utilized the sensitivity of 1s3p X-ray emission spectroscopy (Kβ XES) to the oxidation and spin states of 3d transition-metal ions to determine the cobalt-specific electronic structure of valence tautomers. A comparison of their Kβ XES spectra with the spectra of cobalt coordination complexes with known oxidation and spin states demonstrates that the low-temperature valence tautomer can be described asmore » a low-spin Co III configuration and the high-temperature valence tautomer as a high-spin Co II configuration. This conclusion is further supported by Co L-edge X-ray absorption spectroscopy (L-edge XAS) of the high-temperature valence tautomers and ligand-field atomic-multiplet calculations of the Kβ XES and L-edge XAS spectra. In conclusion, the nature and strength of the magnetic exchange interaction between the cobalt center and SQ – in cobalt valence tautomers is discussed in view of the effective spin at the Co site from Kβ XES and the molecular spin moment from magnetic susceptibility measurements.« less

  18. Charge and Spin-State Characterization of Cobalt Bis( o-dioxolene) Valence Tautomers Using Co Kβ X-ray Emission and L-Edge X-ray Absorption Spectroscopies

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Liang, H. Winnie; Kroll, Thomas; Nordlund, Dennis

    The valence tautomeric states of Co(phen)(3,5-DBQ) 2 and Co(tmeda)(3,5-DBQ) 2, where 3,5-DBQ is either the semiquinone (SQ –) or catecholate (Cat 2–) form of 3,5-di- tert-butyl-1,2-benzoquinone, have been examined by a series of cobalt-specific X-ray spectroscopies. In this work, we have utilized the sensitivity of 1s3p X-ray emission spectroscopy (Kβ XES) to the oxidation and spin states of 3d transition-metal ions to determine the cobalt-specific electronic structure of valence tautomers. A comparison of their Kβ XES spectra with the spectra of cobalt coordination complexes with known oxidation and spin states demonstrates that the low-temperature valence tautomer can be described asmore » a low-spin Co III configuration and the high-temperature valence tautomer as a high-spin Co II configuration. This conclusion is further supported by Co L-edge X-ray absorption spectroscopy (L-edge XAS) of the high-temperature valence tautomers and ligand-field atomic-multiplet calculations of the Kβ XES and L-edge XAS spectra. In conclusion, the nature and strength of the magnetic exchange interaction between the cobalt center and SQ – in cobalt valence tautomers is discussed in view of the effective spin at the Co site from Kβ XES and the molecular spin moment from magnetic susceptibility measurements.« less

  19. Super-resolved terahertz microscopy by knife-edge scan

    NASA Astrophysics Data System (ADS)

    Giliberti, V.; Flammini, M.; Ciano, C.; Pontecorvo, E.; Del Re, E.; Ortolani, M.

    2017-08-01

    We present a compact, all solid-state THz confocal microscope operating at 0.30 THz that achieves super-resolution by using the knife-edge scan approach. In the final reconstructed image, a lateral resolution of 60 μm ≍ λ/17 is demonstrated when the knife-edge is deep in the near-field of the sample surface. When the knife-edge is lifted up to λ/4 from the sample surface, a certain degree of super-resolution is maintained with a resolution of 0.4 mm, i.e. more than a factor 2 if compared to the diffraction-limited scheme. The present results open an interesting path towards super-resolved imaging with in-depth information that would be peculiar to THz microscopy systems.

  20. Accurate predictions of iron redox state in silicate glasses: A multivariate approach using X-ray absorption spectroscopy

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Dyar, M. Darby; McCanta, Molly; Breves, Elly

    2016-03-01

    Pre-edge features in the K absorption edge of X-ray absorption spectra are commonly used to predict Fe3+ valence state in silicate glasses. However, this study shows that using the entire spectral region from the pre-edge into the extended X-ray absorption fine-structure region provides more accurate results when combined with multivariate analysis techniques. The least absolute shrinkage and selection operator (lasso) regression technique yields %Fe3+ values that are accurate to ±3.6% absolute when the full spectral region is employed. This method can be used across a broad range of glass compositions, is easily automated, and is demonstrated to yield accurate resultsmore » from different synchrotrons. It will enable future studies involving X-ray mapping of redox gradients on standard thin sections at 1 × 1 μm pixel sizes.« less

  1. Accurate predictions of iron redox state in silicate glasses: A multivariate approach using X-ray absorption spectroscopy

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Dyar, M. Darby; McCanta, Molly; Breves, Elly

    2016-03-01

    Pre-edge features in the K absorption edge of X-ray absorption spectra are commonly used to predict Fe 3+ valence state in silicate glasses. However, this study shows that using the entire spectral region from the pre-edge into the extended X-ray absorption fine-structure region provides more accurate results when combined with multivariate analysis techniques. The least absolute shrinkage and selection operator (lasso) regression technique yields %Fe 3+ values that are accurate to ±3.6% absolute when the full spectral region is employed. This method can be used across a broad range of glass compositions, is easily automated, and is demonstrated to yieldmore » accurate results from different synchrotrons. It will enable future studies involving X-ray mapping of redox gradients on standard thin sections at 1 × 1 μm pixel sizes.« less

  2. Free-Free Absorption on Parsec Scales in Seyfert Galaxies

    NASA Astrophysics Data System (ADS)

    Roy, A. L.; Ulvestad, J. S.; Wilson, A. S.; Colbert, E. J. M.; Mundell, C. G.; Wrobel, J. M.; Norris, R. P.; Falcke, H.; Krichbaum, T.

    Seyfert galaxies come in two main types (types 1 and 2) and the difference is probably due to obscuration of the nucleus by a torus of dense molecular material. The inner edge of the torus is expected to be ionized by optical and ultraviolet emission from the active nucleus, and will radiate direct thermal emission (e.g. NGC 1068) and will cause free-free absorption of nuclear radio components viewed through the torus (e.g. Mrk 231, Mrk 348, NGC 2639). However, the nuclear radio sources in Seyfert galaxies are weak compared to radio galaxies and quasars, demanding high sensitivity to study these effects. We have been making sensitive phase referenced VLBI observations at wavelengths between 21 and 2 cm where the free-free turnover is expected, looking for parsec-scale absorption and emission. We find that free-free absorption is common (e.g. in Mrk 348, Mrk 231, NGC 2639, NGC 1068) although compact jets are still visible, and the inferred density of the absorber agrees with the absorption columns inferred from X-ray spectra (Mrk 231, Mrk 348, NGC 2639). We find one-sided parsec-scale jets in Mrk 348 and Mrk 231, and we measure low jet speeds (typically £ 0.1 c). The one-sidedness probably is not due to Doppler boosting, but rather is probably free-free absorption. Plasma density required to produce the absorption is Ne 3 2 105 cm-3 assuming a path length of 0.1 pc, typical of that expected at the inner edge of the obscuring torus.

  3. Edge analyzing properties of center/surround response functions in cybernetic vision

    NASA Technical Reports Server (NTRS)

    Jobson, D. J.

    1984-01-01

    The ability of center/surround response functions to make explicit high resolution spatial information in optical images was investigated by performing convolutions of two dimensional response functions and image intensity functions (mainly edges). The center/surround function was found to have the unique property of separating edge contrast from shape variations and of providing a direct basis for determining contrast and subsequently shape of edges in images. Computationally simple measures of contrast and shape were constructed for potential use in cybernetic vision systems. For one class of response functions these measures were found to be reasonably resilient for a range of scan direction and displacements of the response functions relative to shaped edges. A pathological range of scan directions was also defined and methods for detecting and handling these cases were developed. The relationship of these results to biological vision is discussed speculatively.

  4. Edge-Preserving Image Smoothing Constraint in Multivariate Curve Resolution-Alternating Least Squares (MCR-ALS) of Hyperspectral Data.

    PubMed

    Hugelier, Siewert; Vitale, Raffaele; Ruckebusch, Cyril

    2018-03-01

    This article explores smoothing with edge-preserving properties as a spatial constraint for the resolution of hyperspectral images with multivariate curve resolution-alternating least squares (MCR-ALS). For each constrained component image (distribution map), irrelevant spatial details and noise are smoothed applying an L 1 - or L 0 -norm penalized least squares regression, highlighting in this way big changes in intensity of adjacent pixels. The feasibility of the constraint is demonstrated on three different case studies, in which the objects under investigation are spatially clearly defined, but have significant spectral overlap. This spectral overlap is detrimental for obtaining a good resolution and additional spatial information should be provided. The final results show that the spatial constraint enables better image (map) abstraction, artifact removal, and better interpretation of the results obtained, compared to a classical MCR-ALS analysis of hyperspectral images.

  5. Broadband X-ray edge-enhancement imaging of a boron fibre on lithium fluoride thin film detector

    NASA Astrophysics Data System (ADS)

    Nichelatti, E.; Bonfigli, F.; Vincenti, M. A.; Cecilia, A.; Vagovič, P.; Baumbach, T.; Montereali, R. M.

    2016-10-01

    The white beam (∼6-80 keV) available at the TopoTomo X-ray beamline of the ANKA synchrotron facility (KIT, Karlsruhe, Germany) was used to perform edge-enhancement imaging tests on lithium fluoride radiation detectors. The diffracted X-ray image of a microscopic boron fibre, consisting of tungsten wire wrapped by boron cladding, was projected onto lithium fluoride thin films placed at several distances, from contact to 1 m . X-ray photons cause the local formation of primary and aggregate colour centres in lithium fluoride; these latter, once illuminated under blue light, luminesce forming visible-light patterns-acquired by a confocal laser scanning microscope-that reproduce the intensity of the X-ray diffracted images. The tests demonstrated the excellent performances of lithium fluoride films as radiation detectors at the investigated photon energies. The experimental results are here discussed and compared with those calculated with a model that takes into account all the processes that concern image formation, storing and readout.

  6. A GIHS-based spectral preservation fusion method for remote sensing images using edge restored spectral modulation

    NASA Astrophysics Data System (ADS)

    Zhou, Xiran; Liu, Jun; Liu, Shuguang; Cao, Lei; Zhou, Qiming; Huang, Huawen

    2014-02-01

    High spatial resolution and spectral fidelity are basic standards for evaluating an image fusion algorithm. Numerous fusion methods for remote sensing images have been developed. Some of these methods are based on the intensity-hue-saturation (IHS) transform and the generalized IHS (GIHS), which may cause serious spectral distortion. Spectral distortion in the GIHS is proven to result from changes in saturation during fusion. Therefore, reducing such changes can achieve high spectral fidelity. A GIHS-based spectral preservation fusion method that can theoretically reduce spectral distortion is proposed in this study. The proposed algorithm consists of two steps. The first step is spectral modulation (SM), which uses the Gaussian function to extract spatial details and conduct SM of multispectral (MS) images. This method yields a desirable visual effect without requiring histogram matching between the panchromatic image and the intensity of the MS image. The second step uses the Gaussian convolution function to restore lost edge details during SM. The proposed method is proven effective and shown to provide better results compared with other GIHS-based methods.

  7. Material/element-dependent fluorescence-yield modes on soft X-ray absorption spectroscopy of cathode materials for Li-ion batteries

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Asakura, Daisuke; Hosono, Eiji; Nanba, Yusuke

    2016-03-07

    Here, we evaluate the utilities of fluorescence-yield (FY) modes in soft X-ray absorption spectroscopy (XAS) of several cathodematerials for Li-ion batteries. In the case of total-FY (TFY) XAS for LiNi 0.5Mn 1.5O 4, the line shape of the Mn L 3-edge XAS was largely distorted by the self-absorption and saturation effects, while the distortions were less pronounced at the Ni L 3 edge. The distortions were suppressed for the inverse-partial-FY (IPFY) spectra. We found that, in the cathodematerials, the IPFY XAS is highly effective for the Cr, Mn, and Fe L edges and the TFY and PFY modes are usefulmore » enough for the Ni L edge which is far from the O K edge.« less

  8. Orbital Ordering Transition in La_4Ru_2O_10 probed by O K-edge X-ray Absorption

    NASA Astrophysics Data System (ADS)

    Denlinger, J. D.; Rossnagel, Kai; Allen, J. W.; Khalifah, P.; Mandrus, D.; Cava, R. J.

    2004-03-01

    The layered ruthenate compound La_4Ru_2O_10 undergoes a first order monoclinic-to-triclinic structural phase transition at 160 K. An accompanying loss of the Ru local moment gives evidence for a full orbital ordering transition in which the Ru d_yz orbitals become completely unoccupied in the low temperature phase.(P. Khalifah et al.), Science 297, 2237 (2002). Via hybridization of Ru t_2g and O 2p orbitals this temperature-dependent Ru orbital ordering can be indirectly probed using polarized O K-edge x-ray absorption spectroscopy (XAS). O 1s core-level energy shifts allow O site-specific separation of Ru t_2g hybridizations. Identification of O sites is accomplished using polarized XAS angular dependence as well as by O 2p valence PDOS obtained from site-selective soft x-ray emission. Distinct XAS energy and intensity changes are observed upon cooling through the phase transition and are rationalized within the framework of the complete orbital ordering scenario. Supported by the U.S. NSF at U. Mich. (DMR-03-02825) and by the DOE at the Advanced Light Source (DE-AC03-76SF00098).

  9. Application of backscatter absorption gas imaging to the detection of chemicals related to drug production

    NASA Astrophysics Data System (ADS)

    Kulp, Thomas J.; Garvis, Darrel G.; Kennedy, Randall B.; McRae, Thomas G.

    1991-08-01

    The application of backscatter absorption gas imaging (BAGI) to the detection of gaseous chemical species associated with the production of illegal drugs is considered. BAGI is a gas visualization technique that allows the imaging of over 70 organic vapors at minimum concentrations of a few to several hundred ppm-m. Present BAGI capabilities at Lawrence Livermore National Laboratory and Laser Imaging Systems are discussed. Eighteen different species of interest in drug-law enforcement are identified as being detectable by BAGI. The chemical remote sensing needs of law enforcement officials are described, and the use of BAGI in meeting some of these needs is outlined.

  10. Controlled formation of closed-edge nanopores in graphene

    NASA Astrophysics Data System (ADS)

    He, Kuang; Robertson, Alex W.; Gong, Chuncheng; Allen, Christopher S.; Xu, Qiang; Zandbergen, Henny; Grossman, Jeffrey C.; Kirkland, Angus I.; Warner, Jamie H.

    2015-07-01

    Dangling bonds at the edge of a nanopore in monolayer graphene make it susceptible to back-filling at low temperatures from atmospheric hydrocarbons, leading to potential instability for nanopore applications, such as DNA sequencing. We show that closed edge nanopores in bilayer graphene are robust to back-filling under atmospheric conditions for days. A controlled method for closed edge nanopore formation starting from monolayer graphene is reported using an in situ heating holder and electron beam irradiation within an aberration-corrected transmission electron microscopy. Tailoring of closed-edge nanopore sizes is demonstrated from 1.4-7.4 nm. These results should provide mechanisms for improving the stability of nanopores in graphene for a wide range of applications involving mass transport.Dangling bonds at the edge of a nanopore in monolayer graphene make it susceptible to back-filling at low temperatures from atmospheric hydrocarbons, leading to potential instability for nanopore applications, such as DNA sequencing. We show that closed edge nanopores in bilayer graphene are robust to back-filling under atmospheric conditions for days. A controlled method for closed edge nanopore formation starting from monolayer graphene is reported using an in situ heating holder and electron beam irradiation within an aberration-corrected transmission electron microscopy. Tailoring of closed-edge nanopore sizes is demonstrated from 1.4-7.4 nm. These results should provide mechanisms for improving the stability of nanopores in graphene for a wide range of applications involving mass transport. Electronic supplementary information (ESI) available: Low magnification images, image processing techniques employed, modelling and simulation of closed edge nanoribbon, comprehensive AC-TEM dataset, and supporting analysis. See DOI: 10.1039/c5nr02277k

  11. Temperature dependence of Ti 1s near-edge spectra in Ti-based perovskites: theory and experiment

    NASA Astrophysics Data System (ADS)

    Shirley, Eric; Cockayne, Eric; Ravel, Bruce; Woicik, Joseph

    Ti 1s near-edge spectra (around 4970 eV) in SrTiO3 and PbTiO3 reveal electric-dipole and quadrupole transitions to Ti 3d, 4p and mixed 3d-4p states. Crystal field-split pre-edge features attributed to 1s ->3d transitions are small compared to the main edge jump at the onset of the Ti 4s/4p continuum. Pre-edge and subsequent near-edge features are predicted to be weaker than what is observed, unless one accounts for ferroelectric polarization in PbTiO3 and thermal motion in both compounds. Using density-functional theory molecular dynamics simulations at various temperatures (including sampling two phases of PbTiO3), we capture the statistically averaged root-mean-square deviations of Ti4+ ions from the centers of their oxygen cages. By sampling appropriate snapshots of atomic configurations and averaging Ti 1s absorption spectra computed within a Bethe-Salpeter Equation framework, we obtain absorption spectra that agree well with experiment, including details related to ferroelectric polarization, phase transitions, and fluctuations of atomic coordinates.

  12. Absorption by Spinning Dust: A Contaminant for High-redshift 21 cm Observations

    NASA Astrophysics Data System (ADS)

    Draine, B. T.; Miralda-Escudé, Jordi

    2018-05-01

    Spinning dust grains in front of the bright Galactic synchrotron background can produce a weak absorption signal that could affect measurements of high-redshift 21 cm absorption. At frequencies near 80 MHz where the Experiment to Detect the Global EoR Signature (EDGES) has reported 21 cm absorption at z≈ 17, absorption could be produced by interstellar nanoparticles with radii a≈ 50 \\mathringA in the cold interstellar medium (ISM), with rotational temperature T ≈ 50 K. Atmospheric aerosols could contribute additional absorption. The strength of the absorption depends on the abundance of such grains and on their dipole moments, which are uncertain. The breadth of the absorption spectrum of spinning dust limits its possible impact on measurement of a relatively narrow 21 cm absorption feature.

  13. Multi-edge X-ray absorption spectroscopy study of road dust samples from a traffic area of Venice using stoichiometric and environmental references

    NASA Astrophysics Data System (ADS)

    Valotto, Gabrio; Cattaruzza, Elti; Bardelli, Fabrizio

    2017-02-01

    The appropriate selection of representative pure compounds to be used as reference is a crucial step for successful analysis of X-ray absorption near edge spectroscopy (XANES) data, and it is often not a trivial task. This is particularly true when complex environmental matrices are investigated, being their elemental speciation a priori unknown. In this paper, an investigation on the speciation of Cu, Zn, and Sb based on the use of conventional (stoichiometric compounds) and non-conventional (environmental samples or relevant certified materials) references is explored. This method can be useful in when the effectiveness of XANES analysis is limited because of the difficulty in obtaining a set of references sufficiently representative of the investigated samples. Road dust samples collected along the bridge connecting Venice to the mainland were used to show the potentialities and the limits of this approach.

  14. Observation of Phase Objects by Using an X-ray Microscope with a Foucault Knife-Edge

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Watanabe, N.; Sasaya, T.; Imai, Y.

    2011-09-09

    An x-ray microscope with a zone plate was assembled at the synchrotron radiation source of BL3C, Photon Factory. A Foucault knife-edge was set at the back focal plate of the objective zone plate and phase retrieval was tested by scanning the knife-edge. A preliminary result shows that scanning the knife-edge during exposure was effective for phase retrieval. Phase-contrast tomography was investigated using differential projection images calculated from two Schlieren images with the oppositely oriented knife-edges. Fairly good reconstruction images of polystyrene beads and spores could be obtained.

  15. Two-Dimensional Edge Detection by Guided Mode Resonant Metasurface

    NASA Astrophysics Data System (ADS)

    Saba, Amirhossein; Tavakol, Mohammad Reza; Karimi-Khoozani, Parisa; Khavasi, Amin

    2018-05-01

    In this letter, a new approach to perform edge detection is presented using an all-dielectric CMOS-compatible metasurface. The design is based on guided-mode resonance which provides a high quality factor resonance to make the edge detection experimentally realizable. The proposed structure that is easy to fabricate, can be exploited for detection of edges in two dimensions due to its symmetry. Also, the trade-off between gain and resolution of edge detection is discussed which can be adjusted by appropriate design parameters. The proposed edge detector has also the potential to be used in ultrafast analog computing and image processing.

  16. Design, Fabrication and Testing of Multilayer Coated X-Ray Optics for the Water Window Imaging X-Ray Microscope

    NASA Technical Reports Server (NTRS)

    Spencer, Dwight C.

    1996-01-01

    Hoover et. al. built and tested two imaging Schwarzschild multilayer microscopes. These instruments were constructed as prototypes for the "Water Window Imaging X-Ray Microscope," which is a doubly reflecting, multilayer x-ray microscope configured to operate within the "water window." The "water window" is the narrow region of the x-ray spectrum between the K absorption edges of oxygen (lamda = 23.3 Angstroms) and of carbon (lamda = 43.62 Angstroms), where water is relatively highly transmissive and carbon is highly absorptive. This property of these materials, thus permits the use of high resolution multilayer x-ray microscopes for producing high contrast images of carbon-based structures within the aqueous physiological environments of living cells. We report the design, fabrication and testing of multilayer optics that operate in this regime.

  17. Imaging Taurine in the Central Nervous System Using Chemically Specific X-ray Fluorescence Imaging at the Sulfur K-Edge

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hackett, Mark J.; Paterson, Phyllis G.; Pickering, Ingrid J.

    A method to image taurine distributions within the central nervous system and other organs has long been sought. Since taurine is small and mobile, it cannot be chemically “tagged” and imaged using conventional immuno-histochemistry methods. Combining numerous indirect measurements, taurine is known to play critical roles in brain function during health and disease and is proposed to act as a neuro-osmolyte, neuro-modulator, and possibly a neuro-transmitter. Elucidation of taurine’s neurochemical roles and importance would be substantially enhanced by a direct method to visualize alterations, due to physiological and pathological events in the brain, in the local concentration of taurine atmore » or near cellular spatial resolution in vivo or in situ in tissue sections. We thus have developed chemically specific X-ray fluorescence imaging (XFI) at the sulfur K-edge to image the sulfonate group in taurine in situ in ex vivo tissue sections. To our knowledge, this represents the first undistorted imaging of taurine distribution in brain at 20 μm resolution. We report quantitative technique validation by imaging taurine in the cerebellum and hippocampus regions of the rat brain. Further, we apply the technique to image taurine loss from the vulnerable CA1 (cornus ammonis 1) sector of the rat hippocampus following global brain ischemia. The location-specific loss of taurine from CA1 but not CA3 neurons following ischemia reveals osmotic stress may be a key factor in delayed neurodegeneration after a cerebral ischemic insult and highlights the significant potential of chemically specific XFI to study the role of taurine in brain disease.« less

  18. Pixel-based absorption correction for dual-tracer fluorescence imaging of receptor binding potential

    PubMed Central

    Kanick, Stephen C.; Tichauer, Kenneth M.; Gunn, Jason; Samkoe, Kimberley S.; Pogue, Brian W.

    2014-01-01

    Ratiometric approaches to quantifying molecular concentrations have been used for decades in microscopy, but have rarely been exploited in vivo until recently. One dual-tracer approach can utilize an untargeted reference tracer to account for non-specific uptake of a receptor-targeted tracer, and ultimately estimate receptor binding potential quantitatively. However, interpretation of the relative dynamic distribution kinetics is confounded by differences in local tissue absorption at the wavelengths used for each tracer. This study simulated the influence of absorption on fluorescence emission intensity and depth sensitivity at typical near-infrared fluorophore wavelength bands near 700 and 800 nm in mouse skin in order to correct for these tissue optical differences in signal detection. Changes in blood volume [1-3%] and hemoglobin oxygen saturation [0-100%] were demonstrated to introduce substantial distortions to receptor binding estimates (error > 30%), whereas sampled depth was relatively insensitive to wavelength (error < 6%). In response, a pixel-by-pixel normalization of tracer inputs immediately post-injection was found to account for spatial heterogeneities in local absorption properties. Application of the pixel-based normalization method to an in vivo imaging study demonstrated significant improvement, as compared with a reference tissue normalization approach. PMID:25360349

  19. The Red Edge Problem in asteroid band parameter analysis

    NASA Astrophysics Data System (ADS)

    Lindsay, Sean S.; Dunn, Tasha L.; Emery, Joshua P.; Bowles, Neil E.

    2016-04-01

    Near-infrared reflectance spectra of S-type asteroids contain two absorptions at 1 and 2 μm (band I and II) that are diagnostic of mineralogy. A parameterization of these two bands is frequently employed to determine the mineralogy of S(IV) asteroids through the use of ordinary chondrite calibration equations that link the mineralogy to band parameters. The most widely used calibration study uses a Band II terminal wavelength point (red edge) at 2.50 μm. However, due to the limitations of the NIR detectors on prominent telescopes used in asteroid research, spectral data for asteroids are typically only reliable out to 2.45 μm. We refer to this discrepancy as "The Red Edge Problem." In this report, we evaluate the associated errors for measured band area ratios (BAR = Area BII/BI) and calculated relative abundance measurements. We find that the Red Edge Problem is often not the dominant source of error for the observationally limited red edge set at 2.45 μm, but it frequently is for a red edge set at 2.40 μm. The error, however, is one sided and therefore systematic. As such, we provide equations to adjust measured BARs to values with a different red edge definition. We also provide new ol/(ol+px) calibration equations for red edges set at 2.40 and 2.45 μm.

  20. First-Principles Fe L 2,3 -Edge and O K-Edge XANES and XMCD Spectra for Iron Oxides

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sassi, Michel; Pearce, Carolyn I.; Bagus, Paul S.

    X-ray absorption near-edge structure (XANES) and X-ray magnetic circular dichroism (XMCD) spectroscopies are tools in widespread use for providing detailed local atomic structure, oxidation state, and magnetic structure information for materials and organometallic complexes. The analysis of these spectra for transition-metal L-edges is routinely performed on the basis of ligand-field multiplet theory because one- and two-particle mean-field ab initio methods typically cannot describe the multiplet structure. Here we show that multireference configuration interaction (MRCI) calculations can satisfactorily reproduce measured XANES spectra for a range of complex iron oxide materials including hematite and magnetite. MRCI Fe L2,3-edge XANES and XMCD spectramore » of Fe(II)O6, Fe(III)O6, and Fe(III)O4 in magnetite are found to be in very good qualitative agreement with experiment and multiplet calculations. Point-charge embedding and small distortions of the first-shell oxygen ligands have only small effects. Oxygen K-edge XANES/XMCD spectra for magnetite investigated by a real-space Green’s function approach complete the very good qualitative agreement with experiment. Material-specific differences in local coordination and site symmetry are well reproduced, making the approach useful for assigning spectral features to specific oxidation states and coordination environments.« less

  1. Time dependent density functional theory study of the near-edge x-ray absorption fine structure of benzene in gas phase and on metal surfaces.

    PubMed

    Asmuruf, Frans A; Besley, Nicholas A

    2008-08-14

    The near-edge x-ray absorption fine structure of benzene in the gas phase and adsorbed on the Au(111) and Pt(111) surfaces is studied with time dependent density functional theory. Excitation energies computed with hybrid exchange-correlation functionals are too low compared to experiment. However, after applying a constant shift the spectra are in good agreement with experiment. For benzene on the Au(111) surface, two bands arising from excitation to the e(2u)(pi(*)) and b(2g)(pi(*)) orbitals of benzene are observed for photon incidence parallel to the surface. On Pt(111) surface, a broader band arises from excitation to benzene orbitals that are mixed with the surface and have both sigma(*)(Pt-C) and pi(*) characters.

  2. Electronic and chemical state of aluminum from the single- (K) and double-electron excitation (KL II&III, KL I) x-ray absorption near-edge spectra of α-alumina, sodium aluminate, aqueous Al³⁺•(H₂O)₆, and aqueous Al(OH)₄⁻

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Fulton, John L.; Govind, Niranjan; Huthwelker, Thomas

    2015-07-02

    We probe, at high energy resolution, the double electron excitation (KL II&II) x-ray absorption region that lies approximately 115 eV above the main Al K-edge (1566 eV) of α-alumina and sodium aluminate. The two solid standards, α-alumina (octahedral) and sodium aluminate (tetrahedral) are compared to aqueous species that have the same Al coordination symmetries, Al³⁺•6H₂O (octahedral) and Al(OH)₄⁻ (tetrahedral). For the octahedral species, the edge height of the KL II&III-edge is approximately 10% of the main K-edge however the edge height is much weaker (3% of K-edge height) for Al species with tetrahedral symmetry. For the α-alumina and aqueous Al³⁺•6H₂Omore » the KL II&III spectra contain white line features and extended absorption fine structure (EXAFS) that mimics the K-edge spectra. The KL II&III-edge feature interferes with an important region of the extended-XAFS region of the spectra for the K-edge of the crystalline and aqueous standards. The K-edge spectra and K-edge positions are predicted using time-dependent density functional theory (TDDFT). The TDDFT calculations for the K-edge XANES spectra reproduce the observed transitions in the experimental spectra of the four Al species. The KL II&III and KL I onsets and their corresponding chemical shifts for the four standards are estimated using the delta self-consistent field (ΔSCF) method. Research by JLF, NG, EJB, AV, TDS was supported by U.S. Department of Energy’s (DOE), Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences, and Biosciences. NG thanks Amity Andersen for help with the α-Al₂O₃ and tetrahedral sodium aluminate (NaAlO₂) clusters. All the calculations were performed using the Molecular Science Computing Capability at EMSL, a national scientific user facility sponsored by the U.S. Department of Energy’s Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory (PNNL). PNNL

  3. Spatial-Spectral Approaches to Edge Detection in Hyperspectral Remote Sensing

    NASA Astrophysics Data System (ADS)

    Cox, Cary M.

    This dissertation advances geoinformation science at the intersection of hyperspectral remote sensing and edge detection methods. A relatively new phenomenology among its remote sensing peers, hyperspectral imagery (HSI) comprises only about 7% of all remote sensing research - there are five times as many radar-focused peer reviewed journal articles than hyperspectral-focused peer reviewed journal articles. Similarly, edge detection studies comprise only about 8% of image processing research, most of which is dedicated to image processing techniques most closely associated with end results, such as image classification and feature extraction. Given the centrality of edge detection to mapping, that most important of geographic functions, improving the collective understanding of hyperspectral imagery edge detection methods constitutes a research objective aligned to the heart of geoinformation sciences. Consequently, this dissertation endeavors to narrow the HSI edge detection research gap by advancing three HSI edge detection methods designed to leverage HSI's unique chemical identification capabilities in pursuit of generating accurate, high-quality edge planes. The Di Zenzo-based gradient edge detection algorithm, an innovative version of the Resmini HySPADE edge detection algorithm and a level set-based edge detection algorithm are tested against 15 traditional and non-traditional HSI datasets spanning a range of HSI data configurations, spectral resolutions, spatial resolutions, bandpasses and applications. This study empirically measures algorithm performance against Dr. John Canny's six criteria for a good edge operator: false positives, false negatives, localization, single-point response, robustness to noise and unbroken edges. The end state is a suite of spatial-spectral edge detection algorithms that produce satisfactory edge results against a range of hyperspectral data types applicable to a diverse set of earth remote sensing applications. This work

  4. Electronic structure and fundamental absorption edges of KPb2Br5, K0.5Rb0.5Pb2Br5, and RbPb2Br5 single crystals

    NASA Astrophysics Data System (ADS)

    Tarasova, A. Yu.; Isaenko, L. I.; Kesler, V. G.; Pashkov, V. M.; Yelisseyev, A. P.; Denysyuk, N. M.; Khyzhun, O. Yu.

    2012-05-01

    X-ray photoelectron core-level and valence-band spectra for pristine and Ar+-ion irradiated (001) surfaces of KPb2Br5, K0.5Rb0.5Pb2Br5, and RbPb2Br5 single crystals grown by the Bridgman method have been measured and fundamental absorption edges of the ternary bromides have been recorded in the polarized light at 300 K and 80 K. The present X-ray photoelectron spectroscopy (XPS) results reveal high chemical stability of (001) surfaces of KxRb1-xPb2Br5 (x=0, 0.5, and 1.0) single crystals. Substitution of potassium for rubidium in KxRb1-xPb2Br5 does not cause any changes of binding energy values and shapes of the XPS constituent element core-level spectra. Measurements of the fundamental absorption edges indicate that band gap energy, Eg, increases by about 0.14 and 0.19 eV when temperature decreases from 300 K to 80 K in KPb2Br5 and RbPb2Br5, respectively. Furthermore, there is no dependence of the Eg value for KPb2Br5 upon the light polarization, whilst the band gap energy value for RbPb2Br5 is bigger by 0.03-0.05 eV in the case of E‖c compared to those in the cases of E‖a and E‖b.

  5. Oscillations at B Ring Edge

    NASA Image and Video Library

    2010-11-01

    This image obtained by NASA Cassini spacecraft of the outer edge of Saturn?s B ring, reveals the combined effects of a tugging moon and oscillations that can naturally occur in disks like Saturn rings and spiral galaxies.

  6. X-ray Absorption Near Edge Structure Spectroscopy to Resolve the in Vivo Chemistry of the Redox-Active Indazolium trans-[Tetrachlorobis(1H-indazole)ruthenate(III)] (KP1019)

    PubMed Central

    2013-01-01

    Indazolium trans-[tetrachlorobis(1H-indazole)ruthenate(III)] (1, KP1019) and its analogue sodium trans-[tetrachlorobis(1H-indazole)ruthenate(III)] (2, KP1339) are promising redox-active anticancer drug candidates that were investigated with X-ray absorption near edge structure spectroscopy. The analysis was based on the concept of the coordination charge and ruthenium model compounds representing possible coordinations and oxidation states in vivo. 1 was investigated in citrate saline buffer (pH 3.5) and in carbonate buffer (pH 7.4) at 37 °C for different time intervals. Interaction studies on 1 with glutathione in saline buffer and apo-transferrin in carbonate buffer were undertaken, and the coordination of 1 and 2 in tumor tissues was studied too. The most likely coordinations and oxidation states of the compound under the above mentioned conditions were assigned. Microprobe X-ray fluorescence of tumor thin sections showed the strong penetration of ruthenium into the tumor tissue, with the highest concentrations near blood vessels and in the edge regions of the tissue samples. PMID:23282017

  7. Effects of temperature-dependent molecular absorption coefficients on the thermal infrared remote sensing of the earth surface

    NASA Technical Reports Server (NTRS)

    Wan, Zhengming; Dozier, Jeff

    1992-01-01

    The effect of temperature-dependent molecular absorption coefficients on thermal infrared spectral signatures measured from satellite sensors is investigated by comparing results from the atmospheric transmission and radiance codes LOWTRAN and MODTRAN and the accurate multiple scattering radiative transfer model ATRAD for different atmospheric profiles. The sensors considered include the operational NOAA AVHRR and two research instruments planned for NASA's Earth Observing System (EOS): MODIS-N (Moderate Resolution Imaging Spectrometer-Nadir-Mode) and ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer). The difference in band transmittance is as large as 6 percent for some thermal bands within atmospheric windows and more than 30 percent near the edges of these atmospheric windows. The effect of temperature-dependent molecular absorption coefficients on satellite measurements of sea-surface temperature can exceed 0.6 K. Quantitative comparison and factor analysis indicate that more accurate measurements of molecular absorption coefficients and better radiative transfer simulation methods are needed to achieve SST accuracy of 0.3 K, as required for global numerical models of climate, and to develop land-surface temperature algorithms at the 1-K accuracy level.

  8. Layered motion segmentation and depth ordering by tracking edges.

    PubMed

    Smith, Paul; Drummond, Tom; Cipolla, Roberto

    2004-04-01

    This paper presents a new Bayesian framework for motion segmentation--dividing a frame from an image sequence into layers representing different moving objects--by tracking edges between frames. Edges are found using the Canny edge detector, and the Expectation-Maximization algorithm is then used to fit motion models to these edges and also to calculate the probabilities of the edges obeying each motion model. The edges are also used to segment the image into regions of similar color. The most likely labeling for these regions is then calculated by using the edge probabilities, in association with a Markov Random Field-style prior. The identification of the relative depth ordering of the different motion layers is also determined, as an integral part of the process. An efficient implementation of this framework is presented for segmenting two motions (foreground and background) using two frames. It is then demonstrated how, by tracking the edges into further frames, the probabilities may be accumulated to provide an even more accurate and robust estimate, and segment an entire sequence. Further extensions are then presented to address the segmentation of more than two motions. Here, a hierarchical method of initializing the Expectation-Maximization algorithm is described, and it is demonstrated that the Minimum Description Length principle may be used to automatically select the best number of motion layers. The results from over 30 sequences (demonstrating both two and three motions) are presented and discussed.

  9. Structure formation in organic thin films observed in real time by energy dispersive near-edge x-ray absorption fine-structure spectroscopy

    NASA Astrophysics Data System (ADS)

    Scholz, M.; Sauer, C.; Wiessner, M.; Nguyen, N.; Schöll, A.; Reinert, F.

    2013-08-01

    We study the structure formation of 1,4,5,8-naphthalene-tetracarboxylicacid-dianhydride (NTCDA) multilayer films on Ag(111) surfaces by energy dispersive near-edge x-ray absorption fine-structure spectroscopy (NEXAFS) and photoelectron spectroscopy. The time resolution of seconds of the method allows us to identify several sub-processes, which occur during the post-growth three-dimensional structural ordering, as well as their characteristic time scales. After deposition at low temperature the NTCDA molecules are preferentially flat lying and the films exhibit no long-range order. Upon annealing the molecules flip into an upright orientation followed by an aggregation in a transient phase which exists for several minutes. Finally, three-dimensional islands are established with bulk-crystalline structure involving substantial mass transport on the surface and morphological roughening. By applying the Kolmogorov-Johnson-Mehl-Avrami model the activation energies of the temperature-driven sub-processes can be derived from the time evolution of the NEXAFS signal.

  10. The Landsat Image Mosaic of Antarctica (LIMA): A Cutting-Edge Way for Students and Teachers to Learn about Antarctica

    ERIC Educational Resources Information Center

    Campbell, Brian; Bindschadler, Robert

    2009-01-01

    By studying Antarctica via satellite and through ground-truthing research, we can learn where the ice is melting and why. The Landsat Image Mosaic of Antarctica (LIMA), a new and cutting-edge way for scientists, researchers, educators, students, and the public to look at Antarctica, supports this research and allows for unprecedented views of our…

  11. GT1_mbaes_1: HERschel Observations of Edge-on Spirals (HEROES)

    NASA Astrophysics Data System (ADS)

    Baes, M.

    2010-03-01

    We propose to use PACS and SPIRE to map the dust distribution in a sample of seven large edge-on spiral galaxies with regular dust lanes. We will look for the presence of cold dust at large galactocentric radii and investigate the link between dust, gas and metallicity as a function of radius. We will also constrain the vertical distribution of the dust and particularly look for dust emission at large heights above the plane of the galaxies. We will compare the observed Herschel maps with simulated maps resulting from detailed radiative transfer models based on optical and near-infrared images. This will enable us to investigate whether we can confirm the existence of a dust energy balance problem suggested by previous observations (the dust seen in absorption in optical maps underestimates the dust seen in emission) and investigate possible ways to alleviate this potential problem.

  12. Imaging electronic trap states in perovskite thin films with combined fluorescence and femtosecond transient absorption microscopy

    DOE PAGES

    Xiao, Kai; Ma, Ying -Zhong; Simpson, Mary Jane; ...

    2016-04-22

    Charge carrier trapping degrades the performance of organometallic halide perovskite solar cells. To characterize the locations of electronic trap states in a heterogeneous photoactive layer, a spatially resolved approach is essential. Here, we report a comparative study on methylammonium lead tri-iodide perovskite thin films subject to different thermal annealing times using a combined photoluminescence (PL) and femtosecond transient absorption microscopy (TAM) approach to spatially map trap states. This approach coregisters the initially populated electronic excited states with the regions that recombine radiatively. Although the TAM images are relatively homogeneous for both samples, the corresponding PL images are highly structured. Themore » remarkable variation in the PL intensities as compared to transient absorption signal amplitude suggests spatially dependent PL quantum efficiency, indicative of trapping events. Furthermore, detailed analysis enables identification of two trapping regimes: a densely packed trapping region and a sparse trapping area that appear as unique spatial features in scaled PL maps.« less

  13. Particle-in-a-box model of exciton absorption and electroabsorption in conjugated polymers

    NASA Astrophysics Data System (ADS)

    Pedersen, Thomas G.

    2000-12-01

    The recently proposed particle-in-a-box model of one-dimensional excitons in conjugated polymers is applied in calculations of optical absorption and electroabsorption spectra. It is demonstrated that for polymers of long conjugation length a superposition of single exciton resonances produces a line shape characterized by a square-root singularity in agreement with experimental spectra near the absorption edge. The effects of finite conjugation length on both absorption and electroabsorption spectra are analyzed.

  14. Experiment to Determine the Absorption Coefficient of Gamma Rays as a Function of Energy.

    ERIC Educational Resources Information Center

    Ouseph, P. J.; And Others

    1982-01-01

    Simpler than x-ray diffractometer experiments, the experiment described illustrates certain concepts regarding the interaction of electromagnetic rays with matter such as the exponential decrease in the intensity with absorber thickness, variation of the coefficient of absorption with energy, and the effect of the K-absorption edge on the…

  15. Leading-edge vortex lifts swifts.

    PubMed

    Videler, J J; Stamhuis, E J; Povel, G D E

    2004-12-10

    The current understanding of how birds fly must be revised, because birds use their hand-wings in an unconventional way to generate lift and drag. Physical models of a common swift wing in gliding posture with a 60 degrees sweep of the sharp hand-wing leading edge were tested in a water tunnel. Interactions with the flow were measured quantitatively with digital particle image velocimetry at Reynolds numbers realistic for the gliding flight of a swift between 3750 and 37,500. The results show that gliding swifts can generate stable leading-edge vortices at small (5 degrees to 10 degrees) angles of attack. We suggest that the flow around the arm-wings of most birds can remain conventionally attached, whereas the swept-back hand-wings generate lift with leading-edge vortices.

  16. Electronic structure of transition metal-cysteine complexes from X-ray absorption spectroscopy.

    PubMed

    Leung, Bonnie O; Jalilehvand, Farideh; Szilagyi, Robert K

    2008-04-17

    The electronic structures of HgII, NiII, CrIII, and MoV complexes with cysteine were investigated by sulfur K-edge X-ray absorption near-edge structure (XANES) spectroscopy and density functional theory. The covalency in the metal-sulfur bond was determined by analyzing the intensities of the electric-dipole allowed pre-edge features appearing in the XANES spectra below the ionization threshold. Because of the well-defined structures of the selected cysteine complexes, the current work provides a reference set for further sulfur K-edge XAS studies of bioinorganic active sites with transition metal-sulfur bonds from cysteine residues as well as more complex coordination compounds with thiolate ligands.

  17. Practical Study for the Properties of Hueckel Edge Detection Operator

    NASA Astrophysics Data System (ADS)

    Jabbar, Hameed M. Abdul; Hatem, Amal J.; Ameer, Inbethaq M. A. Abdul

    2018-05-01

    The first practical study for the Hueckel edge detection operator was presented in this research, where it is tested on standard step edge set images. A number of criteria were adopted to evaluate its practical performance, which is the accuracy in detecting the edges direction, the error in the edges location (dislocation), edges width, the calculated edge goodness criterion and the consumed execution time. These criteria were studied with the edge direction and the used disk radius of the Hueckel edge detection operator. Important notes were recorded for the performance of this operator depending on the direction of the edge and/or with the radius of the used disk. There is a variation in the performance of the operator in terms of precision in detecting of the edges direction and position. A discussion was presented for the all criteria adopted in the research.

  18. Near-edge study of gold-substituted YBa2Cu3O(7-delta)

    NASA Technical Reports Server (NTRS)

    Ruckman, Mark W.; Hepp, Aloysius F.

    1991-01-01

    The valence of Cu and Au in YBa2Au0.3Cu2.7O7-delta was investigated using X-ray absorption near edge structure (XANES). X-ray and neutron diffraction studies indicate that Au goes on the Cu(1) site and Cu K-edge XANES shows that this has little effect on the oxidation state of the remaining copper. The Au L3 edge develops a white line feature whose position lies between that of trivalent gold oxide and monovalent potassium gold cyanide, and whose height relative to the edge step is smaller than in the two reference compounds. The appearance of the Au L3 edge suggests that fewer Au 3d states are involved in forming the Au-O bond in YBa2Au0.3Cu2.7O7-delta than in trivalent gold oxide.

  19. Near-edge study of gold-substituted YBa2Cu3O(7-delta)

    NASA Technical Reports Server (NTRS)

    Ruckman, Mark W.; Hepp, Aloysius F.

    1991-01-01

    The valence of Cu and Au in YBa2Au0.3Cu2.7O7-delta was investigated using x-ray absorption near edge structure (XANES). X-ray and neutron diffraction studies indicate that Au goes on the Cu(1) site and Cu K-edge XANES shows that this has little effect on the oxidation state of the remaining copper. The Au L3 edge develops a white line feature whose position lies between that of trivalent gold oxide and monovalent potassium gold cyanide, and whose height relative to the edge step is smaller than in the two reference compounds. The appearance of the Au L3 edge suggests that fewer Au 3d states are involved in forming the Au-O bond in YBa2Au0.3Cu2.7O7-delta than in trivalent gold oxide.

  20. Interferogram conditioning for improved Fourier analysis and application to X-ray phase imaging by grating interferometry.

    PubMed

    Montaux-Lambert, Antoine; Mercère, Pascal; Primot, Jérôme

    2015-11-02

    An interferogram conditioning procedure, for subsequent phase retrieval by Fourier demodulation, is presented here as a fast iterative approach aiming at fulfilling the classical boundary conditions imposed by Fourier transform techniques. Interference fringe patterns with typical edge discontinuities were simulated in order to reveal the edge artifacts that classically appear in traditional Fourier analysis, and were consecutively used to demonstrate the correction efficiency of the proposed conditioning technique. Optimization of the algorithm parameters is also presented and discussed. Finally, the procedure was applied to grating-based interferometric measurements performed in the hard X-ray regime. The proposed algorithm enables nearly edge-artifact-free retrieval of the phase derivatives. A similar enhancement of the retrieved absorption and fringe visibility images is also achieved.