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Sample records for aberration corrected scanning

  1. Three-dimensional optical transfer functions in the aberration-corrected scanning transmission electron microscope.

    Science.gov (United States)

    Jones, L; Nellist, P D

    2014-05-01

    In the scanning transmission electron microscope, hardware aberration correctors can now correct for the positive spherical aberration of round electron lenses. These correctors make use of nonround optics such as hexapoles or octupoles, leading to the limiting aberrations often being of a nonround type. Here we explore the effect of a number of potential limiting aberrations on the imaging performance of the scanning transmission electron microscope through their resulting optical transfer functions. In particular, the response of the optical transfer function to changes in defocus are examined, given that this is the final aberration to be tuned just before image acquisition. The resulting three-dimensional optical transfer functions also allow an assessment of the performance of a system for focal-series experiments or optical sectioning applications. © 2014 The Authors Journal of Microscopy © 2014 Royal Microscopical Society.

  2. Aberration-corrected scanning transmission electron microscopy of semiconductors

    International Nuclear Information System (INIS)

    Krivanek, O L; Dellby, N; Murfitt, M F

    2011-01-01

    The scanning transmission electron microscope (STEM) has been able to image individual heavy atoms in a light matrix for some time. It is now able to do much more: it can resolve individual atoms as light as boron in monolayer materials; image atomic columns as light as hydrogen, identify the chemical type of individual isolated atoms from the intensity of their annular dark field (ADF) image and by electron energy loss spectroscopy (EELS); and map elemental composition at atomic resolution by EELS and energy-dispersive X-ray spectroscopy (EDXS). It can even map electronic states, also by EELS, at atomic resolution. The instrumentation developments that have made this level of performance possible are reviewed, and examples of applications to semiconductors and oxides are shown.

  3. Spherical aberration correction in a scanning transmission electron microscope using a sculpted thin film.

    Science.gov (United States)

    Shiloh, Roy; Remez, Roei; Lu, Peng-Han; Jin, Lei; Lereah, Yossi; Tavabi, Amir H; Dunin-Borkowski, Rafal E; Arie, Ady

    2018-06-01

    Nearly eighty years ago, Scherzer showed that rotationally symmetric, charge-free, static electron lenses are limited by an unavoidable, positive spherical aberration. Following a long struggle, a major breakthrough in the spatial resolution of electron microscopes was reached two decades ago by abandoning the first of these conditions, with the successful development of multipole aberration correctors. Here, we use a refractive silicon nitride thin film to tackle the second of Scherzer's constraints and demonstrate an alternative method for correcting spherical aberration in a scanning transmission electron microscope. We reveal features in Si and Cu samples that cannot be resolved in an uncorrected microscope. Our thin film corrector can be implemented as an immediate low cost upgrade to existing electron microscopes without re-engineering of the electron column or complicated operation protocols and can be extended to the correction of additional aberrations. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.

  4. Optical depth sectioning in the aberration-corrected scanning transmission and scanning confocal electron microscope

    International Nuclear Information System (INIS)

    Behan, G; Nellist, P D

    2008-01-01

    The use of spherical aberration correctors in the scanning transmission electron microscope (STEM) has the effect of reducing the depth of field of the microscope, making three-dimensional imaging of a specimen possible by optical sectioning. Depth resolution can be improved further by placing aberration correctors and lenses pre and post specimen to achieve an imaging mode known as scanning confocal electron microscopy (SCEM). We present the calculated incoherent point spread functions (PSF) and optical transfer functions (OTF) of a STEM and SCEM. The OTF for a STEM is shown to have a missing cone region which results in severe blurring along the optic axis, which can be especially severe for extended objects. We also present strategies for reconstruction of experimental data, such as three-dimensional deconvolution of the point spread function.

  5. Non-common path aberration correction in an adaptive optics scanning ophthalmoscope.

    Science.gov (United States)

    Sulai, Yusufu N; Dubra, Alfredo

    2014-09-01

    The correction of non-common path aberrations (NCPAs) between the imaging and wavefront sensing channel in a confocal scanning adaptive optics ophthalmoscope is demonstrated. NCPA correction is achieved by maximizing an image sharpness metric while the confocal detection aperture is temporarily removed, effectively minimizing the monochromatic aberrations in the illumination path of the imaging channel. Comparison of NCPA estimated using zonal and modal orthogonal wavefront corrector bases provided wavefronts that differ by ~λ/20 in root-mean-squared (~λ/30 standard deviation). Sequential insertion of a cylindrical lens in the illumination and light collection paths of the imaging channel was used to compare image resolution after changing the wavefront correction to maximize image sharpness and intensity metrics. Finally, the NCPA correction was incorporated into the closed-loop adaptive optics control by biasing the wavefront sensor signals without reducing its bandwidth.

  6. Design for an aberration corrected scanning electron microscope using miniature electron mirrors.

    Science.gov (United States)

    Dohi, Hideto; Kruit, Pieter

    2018-06-01

    Resolution of scanning electron microscopes (SEMs) is determined by aberrations of the objective lens. It is well known that both spherical and chromatic aberrations can be compensated by placing a 90-degree bending magnet and an electron mirror in the beam path before the objective lens. Nevertheless, this approach has not led to wide use of these aberration correctors, partly because aberrations of the bending magnet can be a serious problem. A mirror corrector with two mirrors placed perpendicularly to the optic axis of an SEM and facing each other is proposed. As a result, only small-angle magnetic deflection is necessary to guide the electron beam around the top mirror to the bottom mirror and around the bottom mirror to the objective lens. The deflection angle, in the order of 50 mrad, is sufficiently small to avoid deflection aberrations. In addition, lateral dispersion at the sample plane can be avoided by making the deflection fields symmetric. Such a corrector system is only possible if the incoming beam can pass the top mirror at a distance in the order of millimeters, without being disturbed by the electric fields of electrodes of the mirror. It is proposed that condition can be satisfied with micro-scale electron optical elements fabricated by using MEMS technology. In the proposed corrector system, the micro-mirrors have to provide the exact negative spherical and chromatic aberrations for correcting the aberration of the objective lens. This exact tuning is accomplished by variable magnification between the micro-mirrors and the objective lens using an additional transfer lens. Extensive optical calculations are reported. Aberrations of the micro-mirrors were analyzed by numerical calculation. Dispersion and aberrations of the deflectors were calculated by using an analytical field model. Combination aberrations caused by the off-axis position of dispersive rays in the mirrors and objective lens were also analyzed. It is concluded that the proposed

  7. Bright-field scanning confocal electron microscopy using a double aberration-corrected transmission electron microscope

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Peng; Behan, Gavin; Kirkland, Angus I. [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Nellist, Peter D., E-mail: peter.nellist@materials.ox.ac.uk [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Cosgriff, Eireann C.; D' Alfonso, Adrian J.; Morgan, Andrew J.; Allen, Leslie J. [School of Physics, University of Melbourne, Parkville, Victoria 3010 (Australia); Hashimoto, Ayako [Advanced Nano-characterization Center, National Institute for Materials Science (NIMS), 3-13 Sakura, Tsukuba 305-0003 (Japan); Takeguchi, Masaki [Advanced Nano-characterization Center, National Institute for Materials Science (NIMS), 3-13 Sakura, Tsukuba 305-0003 (Japan); High Voltage Electron Microscopy Station, NIMS, 3-13 Sakura, Tsukuba 305-0003 (Japan); Mitsuishi, Kazutaka [Advanced Nano-characterization Center, National Institute for Materials Science (NIMS), 3-13 Sakura, Tsukuba 305-0003 (Japan); Quantum Dot Research Center, NIMS, 3-13 Sakura, Tsukuba 305-0003 (Japan); Shimojo, Masayuki [High Voltage Electron Microscopy Station, NIMS, 3-13 Sakura, Tsukuba 305-0003 (Japan); Advanced Science Research Laboratory, Saitama Institute of Technology, 1690 Fusaiji, Fukaya 369-0293 (Japan)

    2011-06-15

    Scanning confocal electron microscopy (SCEM) offers a mechanism for three-dimensional imaging of materials, which makes use of the reduced depth of field in an aberration-corrected transmission electron microscope. The simplest configuration of SCEM is the bright-field mode. In this paper we present experimental data and simulations showing the form of bright-field SCEM images. We show that the depth dependence of the three-dimensional image can be explained in terms of two-dimensional images formed in the detector plane. For a crystalline sample, this so-called probe image is shown to be similar to a conventional diffraction pattern. Experimental results and simulations show how the diffracted probes in this image are elongated in thicker crystals and the use of this elongation to estimate sample thickness is explored. -- Research Highlights: {yields} The confocal probe image in a scanning confocal electron microscopy image reveals information about the thickness and height of the crystalline layer. {yields} The form of the contrast in a three-dimensional bright-field scanning confocal electron microscopy image can be explained in terms of the confocal probe image. {yields} Despite the complicated form of the contrast in bright-field scanning confocal electron microscopy, we see that depth information is transferred on a 10 nm scale.

  8. Bright-field scanning confocal electron microscopy using a double aberration-corrected transmission electron microscope.

    Science.gov (United States)

    Wang, Peng; Behan, Gavin; Kirkland, Angus I; Nellist, Peter D; Cosgriff, Eireann C; D'Alfonso, Adrian J; Morgan, Andrew J; Allen, Leslie J; Hashimoto, Ayako; Takeguchi, Masaki; Mitsuishi, Kazutaka; Shimojo, Masayuki

    2011-06-01

    Scanning confocal electron microscopy (SCEM) offers a mechanism for three-dimensional imaging of materials, which makes use of the reduced depth of field in an aberration-corrected transmission electron microscope. The simplest configuration of SCEM is the bright-field mode. In this paper we present experimental data and simulations showing the form of bright-field SCEM images. We show that the depth dependence of the three-dimensional image can be explained in terms of two-dimensional images formed in the detector plane. For a crystalline sample, this so-called probe image is shown to be similar to a conventional diffraction pattern. Experimental results and simulations show how the diffracted probes in this image are elongated in thicker crystals and the use of this elongation to estimate sample thickness is explored. Copyright © 2010 Elsevier B.V. All rights reserved.

  9. Structural defects in cubic semiconductors characterized by aberration-corrected scanning transmission electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Arroyo Rojas Dasilva, Yadira; Kozak, Roksolana; Erni, Rolf; Rossell, Marta D., E-mail: marta.rossell@empa.ch

    2017-05-15

    The development of new electro-optical devices and the realization of novel types of transistors require a profound understanding of the structural characteristics of new semiconductor heterostructures. This article provides a concise review about structural defects which occur in semiconductor heterostructures on the basis of micro-patterned Si substrates. In particular, one- and two-dimensional crystal defects are being discussed which are due to the plastic relaxation of epitaxial strain caused by the misfit of crystal lattices. Besides a few selected examples from literature, we treat in particular crystal defects occurring in GaAs/Si, Ge/Si and β-SiC/Si structures which are studied by high-resolution annular dark-field scanning transmission electron microscopy. The relevance of this article is twofold; firstly, it should provide a collection of data which are of help for the identification and characterization of defects in cubic semiconductors by means of atomic-resolution imaging, and secondly, the experimental data shall provide a basis for advancing the understanding of device characteristics with the aid of theoretical modelling by considering the defective nature of strained semiconductor heterostructures. - Highlights: • The heterogeneous integration of high-quality compound semiconductors remains a challenge. • Lattice defects cause severe degradation of the semiconductor device performances. • Aberration-corrected HAADF-STEM allows atomic-scale characterization of defects. • An overview of lattice defects found in cubic semiconductors is presented. • Theoretical modelling and calculations are needed to determine the defect properties.

  10. Identification of light elements in silicon nitride by aberration-corrected scanning transmission electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Idrobo, Juan C., E-mail: idrobojc@ornl.gov [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Walkosz, Weronika [Materials Science Division, Argonne National Laboratory, Argonne, IL 60439 (United States); Department of Physics, University of Illinois at Chicago, Chicago, IL 60607 (United States); Klie, Robert F.; Oeguet, Serdar [Department of Physics, University of Illinois at Chicago, Chicago, IL 60607 (United States)

    2012-12-15

    In silicon nitride structural ceramics, the overall mechanical and thermal properties are controlled by the atomic and electronic structures at the interface between the ceramic grains and the amorphous intergranular films (IGFs) formed by various sintering additives. In the last ten years the atomic arrangements of heavy elements (rare-earths) at the Si{sub 3}N{sub 4}/IGF interfaces have been resolved. However, the atomic position of light elements, without which it is not possible to obtain a complete description of the interfaces, has been lacking. This review article details the authors' efforts to identify the atomic arrangement of light elements such as nitrogen and oxygen at the Si{sub 3}N{sub 4}/SiO{sub 2} interface and in bulk Si{sub 3}N{sub 4} using aberration-corrected scanning transmission electron microscopy. -- Highlights: Black-Right-Pointing-Pointer Revealing the atomic structure of the {alpha}-Si{sub 3}N{sub 4}/SiO{sub 2} interface. Black-Right-Pointing-Pointer Identification and lattice location of oxygen impurities in bulk {alpha}-Si{sub 3}N{sub 4}. Black-Right-Pointing-Pointer Short range ordering of nitrogen and oxygen at the {beta}-Si{sub 3}N{sub 4}/SiO{sub 2} interface.

  11. Aberration-corrected scanning transmission electron microscopy for complex transition metal oxides

    Science.gov (United States)

    Qing-Hua, Zhang; Dong-Dong, Xiao; Lin, Gu

    2016-06-01

    Lattice, charge, orbital, and spin are the four fundamental degrees of freedom in condensed matter, of which the interactive coupling derives tremendous novel physical phenomena, such as high-temperature superconductivity (high-T c SC) and colossal magnetoresistance (CMR) in strongly correlated electronic system. Direct experimental observation of these freedoms is essential to understanding the structure-property relationship and the physics behind it, and also indispensable for designing new materials and devices. Scanning transmission electron microscopy (STEM) integrating multiple techniques of structure imaging and spectrum analysis, is a comprehensive platform for providing structural, chemical and electronic information of materials with a high spatial resolution. Benefiting from the development of aberration correctors, STEM has taken a big breakthrough towards sub-angstrom resolution in last decade and always steps forward to improve the capability of material characterization; many improvements have been achieved in recent years, thereby giving an in-depth insight into material research. Here, we present a brief review of the recent advances of STEM by some representative examples of perovskite transition metal oxides; atomic-scale mapping of ferroelectric polarization, octahedral distortions and rotations, valence state, coordination and spin ordering are presented. We expect that this brief introduction about the current capability of STEM could facilitate the understanding of the relationship between functional properties and these fundamental degrees of freedom in complex oxides. Project supported by the National Key Basic Research Project, China (Grant No. 2014CB921002), the Strategic Priority Research Program of Chinese Academy of Sciences (Grant No. XDB07030200), and the National Natural Science Foundation of China (Grant Nos. 51522212 and 51421002).

  12. Nanoscale Energy-Filtered Scanning Confocal Electron Microscopy Using a Double-Aberration-Corrected Transmission Electron Microscope

    International Nuclear Information System (INIS)

    Wang Peng; Behan, Gavin; Kirkland, Angus I.; Nellist, Peter D.; Takeguchi, Masaki; Hashimoto, Ayako; Mitsuishi, Kazutaka; Shimojo, Masayuki

    2010-01-01

    We demonstrate that a transmission electron microscope fitted with two spherical-aberration correctors can be operated as an energy-filtered scanning confocal electron microscope. A method for establishing this mode is described and initial results showing 3D chemical mapping with nanoscale sensitivity to height and thickness changes in a carbon film are presented. Importantly, uncorrected chromatic aberration does not limit the depth resolution of this technique and moreover performs an energy-filtering role, which is explained in terms of a combined depth and energy-loss response function.

  13. In-situ Study of Dynamic Phenomena at Metal Nanosolder Interfaces Using Aberration Corrected Scanning Transmission Electron Microcopy.

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Ping

    2014-10-01

    Controlling metallic nanoparticle (NP) interactions plays a vital role in the development of new joining techniques (nanosolder) that bond at lower processing temperatures but remain viable at higher temperatures. The pr imary objective of this project is t o develop a fundamental understanding of the actual reaction processes, associated atomic mechanisms, and the resulting microstructure that occur during thermally - driven bond formation concerning metal - metal nano - scale (%3C50nm) interfaces. In this LDRD pr oject, we have studied metallic NPs interaction at the elevated temperatures by combining in - situ transmission electron microscopy (TEM ) using an aberration - corrected scanning transmission electron microscope (AC - STEM) and atomic - scale modeling such as m olecular dynamic (MD) simulations. Various metallic NPs such as Ag, Cu and Au are synthesized by chemical routines. Numerous in - situ e xperiments were carried out with focus of the research on study of Ag - Cu system. For the first time, using in - situ STEM he ating experiments , we directly observed t he formation of a 3 - dimensional (3 - D) epitaxial Cu - Ag core - shell nanoparticle during the thermal interaction of Cu and Ag NPs at elevated temperatures (150 - 300 o C). The reaction takes place at temperatures as low as 150 o C and was only observed when care was taken to circumvent the effects of electron beam irradiation during STEM imaging. Atomic - scale modeling verified that the Cu - Ag core - shell structure is energetically favored, and indicated that this phenomenon is a nano - scale effect related to the large surface - to - volume ratio of the NPs. The observation potentially can be used for developing new nanosolder technology that uses Ag shell as the "glue" that stic ks the particles of Cu together. The LDRD has led to several journal publications and numerous conference presentations, and a TA. In addition, we have developed new TEM characterization techniques and phase

  14. Determination of aberration center of Ronchigram for automated aberration correctors in scanning transmission electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Sannomiya, Takumi, E-mail: sannomiya@mtl.titech.ac.jp [Tokyo Institute of Technology, Ookayama, Tokyo (Japan); Sawada, Hidetaka; Nakamichi, Tomohiro; Hosokawa, Fumio [JEOL Limited, Akishima, Tokyo (Japan); Nakamura, Yoshio; Tanishiro, Yasumasa; Takayanagi, Kunio [Tokyo Institute of Technology, Ookayama, Tokyo (Japan)

    2013-12-15

    A generic method to determine the aberration center is established, which can be utilized for aberration calculation and axis alignment for aberration corrected electron microscopes. In this method, decentering induced secondary aberrations from inherent primary aberrations are minimized to find the appropriate axis center. The fitness function to find the optimal decentering vector for the axis was defined as a sum of decentering induced secondary aberrations with properly distributed weight values according to the aberration order. Since the appropriate decentering vector is determined from the aberration values calculated at an arbitrary center axis, only one aberration measurement is in principle required to find the center, resulting in /very fast center search. This approach was tested for the Ronchigram based aberration calculation method for aberration corrected scanning transmission electron microscopy. Both in simulation and in experiments, the center search was confirmed to work well although the convergence to find the best axis becomes slower with larger primary aberrations. Such aberration center determination is expected to fully automatize the aberration correction procedures, which used to require pre-alignment of experienced users. This approach is also applicable to automated aperture positioning. - Highlights: • A generic method to determine the aberration center is established for (S)TEM. • Decentering induced secondary aberrations are utilized to find the center. • The method is tested on Ronchigrams both in simulation and experiment. • Proper weighting of the aberration gives a good convergence. • Larger primary aberration results in a slower convergence.

  15. Towards atomic scale engineering of rare-earth-doped SiAlON ceramics through aberration-corrected scanning transmission electron microscopy

    International Nuclear Information System (INIS)

    Yurdakul, Hilmi; Idrobo, Juan C.; Pennycook, Stephen J.; Turan, Servet

    2011-01-01

    Direct visualization of rare earths in α- and β-SiAlON unit-cells is performed through Z-contrast imaging technique in an aberration-corrected scanning transmission electron microscope. The preferential occupation of Yb and Ce atoms in different interstitial locations of β-SiAlON lattice is demonstrated, yielding higher solubility for Yb than Ce. The triangular-like host sites in α-SiAlON unit cell accommodate more Ce atoms than hexagonal sites in β-SiAlON. We think that our results will be applicable as guidelines for many kinds of rare-earth-doped materials.

  16. Morphological evolution of InAs/InP quantum wires through aberration-corrected scanning transmission electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Sales, D L; Molina, S I [Departamento de Ciencia de los Materiales e I. M. y Q. I., Universidad de Cadiz, Campus Rio San Pedro, E-11510 Puerto Real, Cadiz (Spain); Varela, M; Pennycook, S J [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Galindo, P L [Departamento de Lenguajes y Sistemas Informaticos, Universidad de Cadiz, Campus Rio San Pedro, E-11510 Puerto Real, Cadiz (Spain); Gonzalez, L; Gonzalez, Y [Instituto de Microelectronica de Madrid (CNM, CSIC), Isaac Newton 8, E-28760 Tres Cantos, Madrid (Spain); Fuster, D, E-mail: david.sales@uca.es [UMDO - Unidad Asociada al CSIC-IMM, Instituto de Ciencia de Materiales, Universidad de Valencia, PO Box 22085, 4607 Valencia (Spain)

    2010-08-13

    Evolution of the size, shape and composition of self-assembled InAs/InP quantum wires through the Stranski-Krastanov transition has been determined by aberration-corrected Z-contrast imaging. High resolution compositional maps of the wires in the initial, intermediate and final formation stages are presented. (001) is the main facet at their very initial stage of formation, which is gradually reduced in favour of {l_brace}114{r_brace} or {l_brace}118{r_brace}, ending with the formation of mature quantum wires with {l_brace}114{r_brace} facets. Significant changes in wire dimensions are measured when varying slightly the amount of InAs deposited. These results are used as input parameters to build three-dimensional models that allow calculation of the strain energy during the quantum wire formation process. The observed morphological evolution is explained in terms of the calculated elastic energy changes at the growth front. Regions of the wetting layer close to the nanostructure perimeters have higher strain energy, causing migration of As atoms towards the quantum wire terraces, where the structure is partially relaxed; the thickness of the wetting layer is reduced in these zones and the island height increases until the (001) facet is removed.

  17. Direct observation of dislocation dissociation and Suzuki segregation in a Mg–Zn–Y alloy by aberration-corrected scanning transmission electron microscopy

    International Nuclear Information System (INIS)

    Yang Zhiqing; Chisholm, Matthew F.; Duscher, Gerd; Ma Xiuliang; Pennycook, Stephen J.

    2013-01-01

    Crystal defects in a plastically deformed Mg–Zn–Y alloy have been studied on the atomic scale using aberration-corrected scanning transmission electron microscopy, providing important structural data for understanding the material’s deformation behavior and strengthening mechanisms. Atomic scale structures of deformation stacking faults resulting from dissociation of different types of dislocations have been characterized experimentally, and modeled. Suzuki segregation of Zn and Y along stacking faults formed through dislocation dissociation during plastic deformation at 300 °C is confirmed experimentally on the atomic level. The stacking fault energy of the Mg–Zn–Y alloy is evaluated to be in the range of 4.0–10.3 mJ m −2 . The newly formed nanometer-wide stacking faults with their Zn/Y segregation in Mg grains play an important role in the superior strength of this alloy at elevated temperatures.

  18. Puzzling Intergrowth in Cerium Nitridophosphate Unraveled by Joint Venture of Aberration-Corrected Scanning Transmission Electron Microscopy and Synchrotron Diffraction.

    Science.gov (United States)

    Kloß, Simon D; Neudert, Lukas; Döblinger, Markus; Nentwig, Markus; Oeckler, Oliver; Schnick, Wolfgang

    2017-09-13

    Thorough investigation of nitridophosphates has rapidly accelerated through development of new synthesis strategies. Here we used the recently developed high-pressure metathesis to prepare the first rare-earth metal nitridophosphate, Ce 4 Li 3 P 18 N 35 , with a high degree of condensation >1/2. Ce 4 Li 3 P 18 N 35 consists of an unprecedented hexagonal framework of PN 4 tetrahedra and exhibits blue luminescence peaking at 455 nm. Transmission electron microscopy (TEM) revealed two intergrown domains with slight structural and compositional variations. One domain type shows extremely weak superstructure phenomena revealed by atomic-resolution scanning TEM (STEM) and single-crystal diffraction using synchrotron radiation. The corresponding superstructure involves a modulated displacement of Ce atoms in channels of tetrahedra 6-rings. The displacement model was refined in a supercell as well as in an equivalent commensurate (3 + 2)-dimensional description in superspace group P6 3 (α, β, 0)0(-α - β, α, 0)0. In the second domain type, STEM revealed disordered vacancies of the same Ce atoms that were modulated in the first domain type, leading to sum formula Ce 4-0.5x Li 3 P 18 N 35-1.5x O 1.5x (x ≈ 0.72) of the average structure. The examination of these structural intricacies may indicate the detection limit of synchrotron diffraction and TEM. We discuss the occurrence of either Ce displacements or Ce vacancies that induce the incorporation of O as necessary stabilization of the crystal structure.

  19. Aberration-corrected STEM: current performance and future directions

    Energy Technology Data Exchange (ETDEWEB)

    Nellist, P D [Department of Physics, University of Dublin, Trinity College, Dublin 2 (Ireland); Chisholm, M F [Condensed Matter Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6030 (United States); Lupini, A R [Condensed Matter Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6030 (United States); Borisevich, A [Condensed Matter Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6030 (United States); Jr, W H Sides [Condensed Matter Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6030 (United States); Pennycook, S J [Condensed Matter Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6030 (United States); Dellby, N [Nion Co., 1102 8th St., Kirkland, WA 98033 (United States); Keyse, R [Nion Co., 1102 8th St., Kirkland, WA 98033 (United States); Krivanek, O L [Nion Co., 1102 8th St., Kirkland, WA 98033 (United States); Murfitt, M F [Nion Co., 1102 8th St., Kirkland, WA 98033 (United States); Szilagyi, Z S [Nion Co., 1102 8th St., Kirkland, WA 98033 (United States)

    2006-02-22

    Through the correction of spherical aberration in the scanning transmission electron microscope (STEM), the resolving of a 78 pm atomic column spacing has been demonstrated along with information transfer to 61 pm. The achievement of this resolution required careful control of microscope instabilities, parasitic aberrations and the compensation of uncorrected, higher order aberrations. Many of these issues are improved in a next generation STEM fitted with a new design of aberration corrector, and an initial result demonstrating aberration correction to a convergence semi-angle of 40 mrad is shown. The improved spatial resolution and beam convergence allowed for by such correction has implications for the way in which experiments are performed and how STEM data should be interpreted.

  20. Pulse compressor with aberration correction

    Energy Technology Data Exchange (ETDEWEB)

    Mankos, Marian [Electron Optica, Inc., Palo Alto, CA (United States)

    2015-11-30

    In this SBIR project, Electron Optica, Inc. (EOI) is developing an electron mirror-based pulse compressor attachment to new and retrofitted dynamic transmission electron microscopes (DTEMs) and ultrafast electron diffraction (UED) cameras for improving the temporal resolution of these instruments from the characteristic range of a few picoseconds to a few nanoseconds and beyond, into the sub-100 femtosecond range. The improvement will enable electron microscopes and diffraction cameras to better resolve the dynamics of reactions in the areas of solid state physics, chemistry, and biology. EOI’s pulse compressor technology utilizes the combination of electron mirror optics and a magnetic beam separator to compress the electron pulse. The design exploits the symmetry inherent in reversing the electron trajectory in the mirror in order to compress the temporally broadened beam. This system also simultaneously corrects the chromatic and spherical aberration of the objective lens for improved spatial resolution. This correction will be found valuable as the source size is reduced with laser-triggered point source emitters. With such emitters, it might be possible to significantly reduce the illuminated area and carry out ultrafast diffraction experiments from small regions of the sample, e.g. from individual grains or nanoparticles. During phase I, EOI drafted a set of candidate pulse compressor architectures and evaluated the trade-offs between temporal resolution and electron bunch size to achieve the optimum design for two particular applications with market potential: increasing the temporal and spatial resolution of UEDs, and increasing the temporal and spatial resolution of DTEMs. Specialized software packages that have been developed by MEBS, Ltd. were used to calculate the electron optical properties of the key pulse compressor components: namely, the magnetic prism, the electron mirror, and the electron lenses. In the final step, these results were folded

  1. Catadioptric aberration correction in cathode lens microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Tromp, R.M. [IBM T.J. Watson Research Center, PO Box 218, Yorktown Heights, NY 10598 (United States); Kamerlingh Onnes Laboratory, Leiden Institute of Physics, Niels Bohrweg 2, 2333 CA Leiden (Netherlands)

    2015-04-15

    In this paper I briefly review the use of electrostatic electron mirrors to correct the aberrations of the cathode lens objective lens in low energy electron microscope (LEEM) and photo electron emission microscope (PEEM) instruments. These catadioptric systems, combining electrostatic lens elements with a reflecting mirror, offer a compact solution, allowing simultaneous and independent correction of both spherical and chromatic aberrations. A comparison with catadioptric systems in light optics informs our understanding of the working principles behind aberration correction with electron mirrors, and may point the way to further improvements in the latter. With additional developments in detector technology, 1 nm spatial resolution in LEEM appears to be within reach. - Highlights: • The use of electron mirrors for aberration correction in LEEM/PEEM is reviewed. • A comparison is made with similar systems in light optics. • Conditions for 1 nm spatial resolution are discussed.

  2. Iteration of ultrasound aberration correction methods

    Science.gov (United States)

    Maasoey, Svein-Erik; Angelsen, Bjoern; Varslot, Trond

    2004-05-01

    Aberration in ultrasound medical imaging is usually modeled by time-delay and amplitude variations concentrated on the transmitting/receiving array. This filter process is here denoted a TDA filter. The TDA filter is an approximation to the physical aberration process, which occurs over an extended part of the human body wall. Estimation of the TDA filter, and performing correction on transmit and receive, has proven difficult. It has yet to be shown that this method works adequately for severe aberration. Estimation of the TDA filter can be iterated by retransmitting a corrected signal and re-estimate until a convergence criterion is fulfilled (adaptive imaging). Two methods for estimating time-delay and amplitude variations in receive signals from random scatterers have been developed. One method correlates each element signal with a reference signal. The other method use eigenvalue decomposition of the receive cross-spectrum matrix, based upon a receive energy-maximizing criterion. Simulations of iterating aberration correction with a TDA filter have been investigated to study its convergence properties. A weak and strong human-body wall model generated aberration. Both emulated the human abdominal wall. Results after iteration improve aberration correction substantially, and both estimation methods converge, even for the case of strong aberration.

  3. Aberration Correction in the Brewer Spectrophotometer

    International Nuclear Information System (INIS)

    Johnston, J.E.; Kerr, J.B.; McElroy, C.T.; Wardle, D.I.

    2000-01-01

    The optical design of the Brewer Spectrophotometer has been optimised for measurements in the 300-320 nm wavelength range. An aberration resolution limit that is much less than the 0.6 nm FWHM (full width at half maximum) is achieved by using an Ebert-Fastie spectrometer design, modified by the inclusion tilted lens that optimises performance at 310 nm. The small contribution of the remaining aberration to the measured instrument function is critical to radiometric measurement quality. Ramifications of this design to the development of instrumentation with enhanced scanning abilities are discussed. (author)

  4. The correction of electron lens aberrations

    Energy Technology Data Exchange (ETDEWEB)

    Hawkes, P.W., E-mail: peter.hawkes@cemes.fr

    2015-09-15

    The progress of electron lens aberration correction from about 1990 onwards is chronicled. Reasonably complete lists of publications on this and related topics are appended. A present for Max Haider and Ondrej Krivanek in the year of their 65th birthdays. By a happy coincidence, this review was completed in the year that both Max Haider and Ondrej Krivanek reached the age of 65. It is a pleasure to dedicate it to the two leading actors in the saga of aberration corrector design and construction. They would both wish to associate their colleagues with such a tribute but it is the names of Haider and Krivanek (not forgetting Joachim Zach) that will remain in the annals of electron optics, next to that of Harald Rose. I am proud to know that both regard me as a friend as well as a colleague. - Highlights: • Geometrical aberration correction. • Chromatic aberration correction. • 50 pm resolution. • High-resolution electron energy-loss spectroscopy. • Extensive bibliographies.

  5. The correction of electron lens aberrations

    International Nuclear Information System (INIS)

    Hawkes, P.W.

    2015-01-01

    The progress of electron lens aberration correction from about 1990 onwards is chronicled. Reasonably complete lists of publications on this and related topics are appended. A present for Max Haider and Ondrej Krivanek in the year of their 65th birthdays. By a happy coincidence, this review was completed in the year that both Max Haider and Ondrej Krivanek reached the age of 65. It is a pleasure to dedicate it to the two leading actors in the saga of aberration corrector design and construction. They would both wish to associate their colleagues with such a tribute but it is the names of Haider and Krivanek (not forgetting Joachim Zach) that will remain in the annals of electron optics, next to that of Harald Rose. I am proud to know that both regard me as a friend as well as a colleague. - Highlights: • Geometrical aberration correction. • Chromatic aberration correction. • 50 pm resolution. • High-resolution electron energy-loss spectroscopy. • Extensive bibliographies

  6. An electron microscope for the aberration-corrected era

    Energy Technology Data Exchange (ETDEWEB)

    Krivanek, O.L. [Nion Co., 1102 8th Street, Kirkland, WA 98033 (United States)], E-mail: krivanek.ondrej@gmail.com; Corbin, G.J.; Dellby, N.; Elston, B.F.; Keyse, R.J.; Murfitt, M.F.; Own, C.S.; Szilagyi, Z.S.; Woodruff, J.W. [Nion Co., 1102 8th Street, Kirkland, WA 98033 (United States)

    2008-02-15

    Improved resolution made possible by aberration correction has greatly increased the demands on the performance of all parts of high-end electron microscopes. In order to meet these demands, we have designed and built an entirely new scanning transmission electron microscope (STEM). The microscope includes a flexible illumination system that allows the properties of its probe to be changed on-the-fly, a third-generation aberration corrector which corrects all geometric aberrations up to fifth order, an ultra-responsive yet stable five-axis sample stage, and a flexible configuration of optimized detectors. The microscope features many innovations, such as a modular column assembled from building blocks that can be stacked in almost any order, in situ storage and cleaning facilities for up to five samples, computer-controlled loading of samples into the column, and self-diagnosing electronics. The microscope construction is described, and examples of its capabilities are shown.

  7. An electron microscope for the aberration-corrected era

    International Nuclear Information System (INIS)

    Krivanek, O.L.; Corbin, G.J.; Dellby, N.; Elston, B.F.; Keyse, R.J.; Murfitt, M.F.; Own, C.S.; Szilagyi, Z.S.; Woodruff, J.W.

    2008-01-01

    Improved resolution made possible by aberration correction has greatly increased the demands on the performance of all parts of high-end electron microscopes. In order to meet these demands, we have designed and built an entirely new scanning transmission electron microscope (STEM). The microscope includes a flexible illumination system that allows the properties of its probe to be changed on-the-fly, a third-generation aberration corrector which corrects all geometric aberrations up to fifth order, an ultra-responsive yet stable five-axis sample stage, and a flexible configuration of optimized detectors. The microscope features many innovations, such as a modular column assembled from building blocks that can be stacked in almost any order, in situ storage and cleaning facilities for up to five samples, computer-controlled loading of samples into the column, and self-diagnosing electronics. The microscope construction is described, and examples of its capabilities are shown

  8. Investigating the chemical and morphological evolution of GaAs capped InAs/InP quantum dots emitting at 1.5μm using aberration-corrected scanning transmission electron microscopy

    DEFF Research Database (Denmark)

    Kadkhodazadeh, Shima; Semenova, Elizaveta; Yvind, Kresten

    2011-01-01

    The emission wavelength of InAs quantum dots grown on InP has been shown to shift to the technologically desirable 1.5μm with the deposition of 1–2 monolayers of GaAs on top of the quantum dots. Here, we use aberration-corrected scanning transmission electron microscopy to investigate morphological...... and compositional changes occurring to the quantum dots as a result of the deposition of 1.7 monolayers of GaAs on top of them, prior to complete overgrowth with InP. The results are compared with theoretical models describing the overgrowth process....

  9. Simulation of eye-tracker latency, spot size, and ablation pulse depth on the correction of higher order wavefront aberrations with scanning spot laser systems.

    Science.gov (United States)

    Bueeler, Michael; Mrochen, Michael

    2005-01-01

    The aim of this theoretical work was to investigate the robustness of scanning spot laser treatments with different laser spot diameters and peak ablation depths in case of incomplete compensation of eye movements due to eye-tracker latency. Scanning spot corrections of 3rd to 5th Zernike order wavefront errors were numerically simulated. Measured eye-movement data were used to calculate the positioning error of each laser shot assuming eye-tracker latencies of 0, 5, 30, and 100 ms, and for the case of no eye tracking. The single spot ablation depth ranged from 0.25 to 1.0 microm and the spot diameter from 250 to 1000 microm. The quality of the ablation was rated by the postoperative surface variance and the Strehl intensity ratio, which was calculated after a low-pass filter was applied to simulate epithelial surface smoothing. Treatments performed with nearly ideal eye tracking (latency approximately 0) provide the best results with a small laser spot (0.25 mm) and a small ablation depth (250 microm). However, combinations of a large spot diameter (1000 microm) and a small ablation depth per pulse (0.25 microm) yield the better results for latencies above a certain threshold to be determined specifically. Treatments performed with tracker latencies in the order of 100 ms yield similar results as treatments done completely without eye-movement compensation. CONCWSIONS: Reduction of spot diameter was shown to make the correction more susceptible to eye movement induced error. A smaller spot size is only beneficial when eye movement is neutralized with a tracking system with a latency <5 ms.

  10. Measuring and correcting aberrations of a cathode objective lens

    International Nuclear Information System (INIS)

    Tromp, R.M.

    2011-01-01

    In this paper I discuss several theoretical and practical aspects related to measuring and correcting the chromatic and spherical aberrations of a cathode objective lens as used in Low Energy Electron Microscopy (LEEM) and Photo Electron Emission Microscopy (PEEM) experiments. Special attention is paid to the various components of the cathode objective lens as they contribute to chromatic and spherical aberrations, and affect practical methods for aberration correction. This analysis has enabled us to correct a LEEM instrument for the spherical and chromatic aberrations of the objective lens. -- Research highlights: → Presents a comprehensive theory of the relation between chromatic aberration and lens current in a cathode objective lens. → Presents practical methods for measuring both spherical and chromatic aberrations of a cathode objective lens. → Presents measurements of these aberrations in good agreement with theory. → Presents practical methods for measuring and correcting these aberrations with an electron mirror.

  11. Brief history of the Cambridge STEM aberration correction project and its progeny

    Energy Technology Data Exchange (ETDEWEB)

    Brown, L. Michael [Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, Cambridge CB3 0HE (United Kingdom); Batson, Philip E. [Institute for Advanced Materials, Devices and Nanotechnology, Rutgers University, Piscataway, NJ 08854 (United States); Department of Physics, Rutgers University, Piscataway, NJ 08854 (United States); Department of Materials Science, Rutgers University, Piscataway, NJ 08854 (United States); Dellby, Niklas [Nion Company, 11515 NE 118th Street, Kirkland, WA 98034 (United States); Krivanek, Ondrej L. [Nion Company, 11515 NE 118th Street, Kirkland, WA 98034 (United States); Department of Physics, Arizona State University, Tempe, AZ 85287 (United States)

    2015-10-15

    We provide a brief history of the project to correct the spherical aberration of the scanning transmission electron microscope (STEM) that started in Cambridge (UK) and continued in Kirkland (WA, USA), Yorktown Heights (NY, USA), and other places. We describe the project in the full context of other aberration correction research and related work, partly in response to the incomplete context presented in the paper “In quest of perfection in electron optics: A biographical sketch of Harald Rose on the occasion of his 80th birthday”, recently published in Ultramicroscopy. - Highlights: • We provide a brief history of the Cambridge project to correct the spherical aberration of the scanning transmission electron microscope (STEM). • We describe the project in the full context of other aberration correction work and related research. • We summarize our corrector development work that followed the Cambridge project, and which was the first to reach higher spatial resolution than any non-corrected electron microscope.

  12. Brief history of the Cambridge STEM aberration correction project and its progeny

    International Nuclear Information System (INIS)

    Brown, L. Michael; Batson, Philip E.; Dellby, Niklas; Krivanek, Ondrej L.

    2015-01-01

    We provide a brief history of the project to correct the spherical aberration of the scanning transmission electron microscope (STEM) that started in Cambridge (UK) and continued in Kirkland (WA, USA), Yorktown Heights (NY, USA), and other places. We describe the project in the full context of other aberration correction research and related work, partly in response to the incomplete context presented in the paper “In quest of perfection in electron optics: A biographical sketch of Harald Rose on the occasion of his 80th birthday”, recently published in Ultramicroscopy. - Highlights: • We provide a brief history of the Cambridge project to correct the spherical aberration of the scanning transmission electron microscope (STEM). • We describe the project in the full context of other aberration correction work and related research. • We summarize our corrector development work that followed the Cambridge project, and which was the first to reach higher spatial resolution than any non-corrected electron microscope

  13. Correction for polychromatic aberration in computed tomography images

    International Nuclear Information System (INIS)

    Naparstek, A.

    1979-01-01

    A method and apparatus for correcting a computed tomography image for polychromatic aberration caused by the non-linear interaction (i.e. the energy dependent attenuation characteristics) of different body constituents, such as bone and soft tissue, with a polychromatic X-ray beam are described in detail. An initial image is conventionally computed from path measurements made as source and detector assembly scan a body section. In the improvement, each image element of the initial computed image representing attenuation is recorded in a store and is compared with two thresholds, one representing bone and the other soft tissue. Depending on the element value relative to the thresholds, a proportion of the respective constituent is allocated to that element location and corresponding bone and soft tissue projections are determined and stored. An error projection generator calculates projections of polychromatic aberration errors in the raw image data from recalled bone and tissue projections using a multidimensional polynomial function which approximates the non-linear interaction involved. After filtering, these are supplied to an image reconstruction computer to compute image element correction values which are subtracted from raw image element values to provide a corrected reconstructed image for display. (author)

  14. Adaptive aberration correction using a triode hyperbolic electron mirror

    International Nuclear Information System (INIS)

    Fitzgerald, J.P.S.; Word, R.C.; Koenenkamp, R.

    2011-01-01

    A converging electron mirror can be used to compensate spherical and chromatic aberrations in an electron microscope. This paper presents an analytical solution to a novel triode (three electrode) hyperbolic mirror as an improvement to the well-known diode (two electrode) hyperbolic mirror for aberration correction. A weakness of the diode mirror is a lack of flexibility in changing the chromatic and spherical aberration coefficients independently without changes in the mirror geometry. In order to remove this limitation, a third electrode can be added. We calculate the optical properties of the resulting triode mirror analytically on the basis of a simple model field distribution. We present the optical properties-the object/image distance, z 0 , and the coefficients of spherical and chromatic aberration, C s and C c , of both mirror types from an analysis of electron trajectories in the mirror field. From this analysis, we demonstrate that while the properties of both designs are similar, the additional parameters in the triode mirror improve the range of aberration that can be corrected. The triode mirror is also able to provide a dynamic adjustment range of chromatic aberration for fixed spherical aberration and focal length, or any permutation of these three parameters. While the dynamic range depends on the values of aberration correction needed, a nominal 10% tuning range is possible for most configurations accompanied by less than 1% change in the other two properties. -- Highlights: → Electrostatic aberration correction for chromatic and spherical aberration in electron optics. → Simultaneous correction of spherical and chromatic aberrations over a wide, adjustable range. → Analytic and quantitative description of correction parameters.

  15. Prospects for electron beam aberration correction using sculpted phase masks

    Energy Technology Data Exchange (ETDEWEB)

    Shiloh, Roy, E-mail: royshilo@post.tau.ac.il; Remez, Roei; Arie, Ady

    2016-04-15

    Technological advances in fabrication methods allowed the microscopy community to take incremental steps towards perfecting the electron microscope, and magnetic lens design in particular. Still, state of the art aberration-corrected microscopes are yet 20–30 times shy of the theoretical electron diffraction limit. Moreover, these microscopes consume significant physical space and are very expensive. Here, we show how a thin, sculpted membrane is used as a phase-mask to induce specific aberrations into an electron beam probe in a standard high resolution TEM. In particular, we experimentally demonstrate beam splitting, two-fold astigmatism, three-fold astigmatism, and spherical aberration. - Highlights: • Thin membranes can be used as aberration correctors in electron columns. • We demonstrate tilt, twofold-, threefold-astigmatism, and spherical aberrations. • Experimental and physical-optics simulation results are in good agreement. • Advantages in cost, size, nonmagnetism, and nearly-arbitrary correction.

  16. Correcting the Chromatic Aberration in Barrel Distortion of Endoscopic Images

    Directory of Open Access Journals (Sweden)

    Y. M. Harry Ng

    2003-04-01

    Full Text Available Modern endoscopes offer physicians a wide-angle field of view (FOV for minimally invasive therapies. However, the high level of barrel distortion may prevent accurate perception of image. Fortunately, this kind of distortion may be corrected by digital image processing. In this paper we investigate the chromatic aberrations in the barrel distortion of endoscopic images. In the past, chromatic aberration in endoscopes is corrected by achromatic lenses or active lens control. In contrast, we take a computational approach by modifying the concept of image warping and the existing barrel distortion correction algorithm to tackle the chromatic aberration problem. In addition, an error function for the determination of the level of centroid coincidence is proposed. Simulation and experimental results confirm the effectiveness of our method.

  17. Aberration-corrected STEM/TEM imaging at 15 kV

    International Nuclear Information System (INIS)

    Sasaki, Takeo; Sawada, Hidetaka; Hosokawa, Fumio; Sato, Yuta; Suenaga, Kazu

    2014-01-01

    The performance of aberration-corrected (scanning) transmission electron microscopy (S/TEM) at an accelerating voltage of 15 kV was evaluated in a low-voltage microscope equipped with a cold-field emission gun and a higher-order aberration corrector. Aberrations up to the fifth order were corrected by the aberration measurement and auto-correction system using the diffractogram tableau method in TEM and Ronchigram analysis in STEM. TEM observation of nanometer-sized particles demonstrated that aberrations up to an angle of 50 mrad were compensated. A TEM image of Si[110] exhibited lattice fringes with a spacing of 0.192 nm, and the power spectrum of the image showed spots corresponding to distances of 0.111 nm. An annular dark-field STEM image of Si[110] showed lattice fringes of (111) and (22¯0) planes corresponding to lattice distances of 0.314 nm and 0.192 nm, respectively. At an accelerating voltage of 15 kV, the developed low-voltage microscope achieved atomic-resolution imaging with a small chromatic aberration and a large uniform phase. - Highlights: • Aberration-corrected STEM/TEM imaging at 15 kV demonstrated lattice fringes of Si[110] single crystal with a spacing of 0.192 nm. • To achieve this performance at a lower accelerating voltage, uniform phase area over 50 mrad is mandatory in Ronchigram and Diffractogram tableau. • This means a higher-order aberration of six-fold astigmatism should be compensated. • In addition, decreasing the effect of chromatic aberration plays an important role for improving the performance of linear scattering component at 15 kV TEM

  18. Integral image rendering procedure for aberration correction and size measurement.

    Science.gov (United States)

    Sommer, Holger; Ihrig, Andreas; Ebenau, Melanie; Flühs, Dirk; Spaan, Bernhard; Eichmann, Marion

    2014-05-20

    The challenge in rendering integral images is to use as much information preserved by the light field as possible to reconstruct a captured scene in a three-dimensional way. We propose a rendering algorithm based on the projection of rays through a detailed simulation of the optical path, considering all the physical properties and locations of the optical elements. The rendered images contain information about the correct size of imaged objects without the need to calibrate the imaging device. Additionally, aberrations of the optical system may be corrected, depending on the setup of the integral imaging device. We show simulation data that illustrates the aberration correction ability and experimental data from our plenoptic camera, which illustrates the capability of our proposed algorithm to measure size and distance. We believe this rendering procedure will be useful in the future for three-dimensional ophthalmic imaging of the human retina.

  19. Revisiting Cross-Channel Information Transfer for Chromatic Aberration Correction

    KAUST Repository

    Sun, Tiancheng; Peng, Yifan; Heidrich, Wolfgang

    2017-01-01

    Image aberrations can cause severe degradation in image quality for consumer-level cameras, especially under the current tendency to reduce the complexity of lens designs in order to shrink the overall size of modules. In simplified optical designs, chromatic aberration can be one of the most significant causes for degraded image quality, and it can be quite difficult to remove in post-processing, since it results in strong blurs in at least some of the color channels. In this work, we revisit the pixel-wise similarity between different color channels of the image and accordingly propose a novel algorithm for correcting chromatic aberration based on this cross-channel correlation. In contrast to recent weak prior-based models, ours uses strong pixel-wise fitting and transfer, which lead to significant quality improvements for large chromatic aberrations. Experimental results on both synthetic and real world images captured by different optical systems demonstrate that the chromatic aberration can be significantly reduced using our approach.

  20. Revisiting Cross-Channel Information Transfer for Chromatic Aberration Correction

    KAUST Repository

    Sun, Tiancheng

    2017-12-25

    Image aberrations can cause severe degradation in image quality for consumer-level cameras, especially under the current tendency to reduce the complexity of lens designs in order to shrink the overall size of modules. In simplified optical designs, chromatic aberration can be one of the most significant causes for degraded image quality, and it can be quite difficult to remove in post-processing, since it results in strong blurs in at least some of the color channels. In this work, we revisit the pixel-wise similarity between different color channels of the image and accordingly propose a novel algorithm for correcting chromatic aberration based on this cross-channel correlation. In contrast to recent weak prior-based models, ours uses strong pixel-wise fitting and transfer, which lead to significant quality improvements for large chromatic aberrations. Experimental results on both synthetic and real world images captured by different optical systems demonstrate that the chromatic aberration can be significantly reduced using our approach.

  1. Joint denoising, demosaicing, and chromatic aberration correction for UHD video

    Science.gov (United States)

    Jovanov, Ljubomir; Philips, Wilfried; Damstra, Klaas Jan; Ellenbroek, Frank

    2017-09-01

    High-resolution video capture is crucial for numerous applications such as surveillance, security, industrial inspection, medical imaging and digital entertainment. In the last two decades, we are witnessing a dramatic increase of the spatial resolution and the maximal frame rate of video capturing devices. In order to achieve further resolution increase, numerous challenges will be facing us. Due to the reduced size of the pixel, the amount of light also reduces, leading to the increased noise level. Moreover, the reduced pixel size makes the lens imprecisions more pronounced, which especially applies to chromatic aberrations. Even in the case when high quality lenses are used some chromatic aberration artefacts will remain. Next, noise level additionally increases due to the higher frame rates. To reduce the complexity and the price of the camera, one sensor captures all three colors, by relying on Color Filter Arrays. In order to obtain full resolution color image, missing color components have to be interpolated, i.e. demosaicked, which is more challenging than in the case of lower resolution, due to the increased noise and aberrations. In this paper, we propose a new method, which jointly performs chromatic aberration correction, denoising and demosaicking. By jointly performing the reduction of all artefacts, we are reducing the overall complexity of the system and the introduction of new artefacts. In order to reduce possible flicker we also perform temporal video enhancement. We evaluate the proposed method on a number of publicly available UHD sequences and on sequences recorded in our studio.

  2. Spherical aberration correction with threefold symmetric line currents.

    Science.gov (United States)

    Hoque, Shahedul; Ito, Hiroyuki; Nishi, Ryuji; Takaoka, Akio; Munro, Eric

    2016-02-01

    It has been shown that N-fold symmetric line current (henceforth denoted as N-SYLC) produces 2N-pole magnetic fields. In this paper, a threefold symmetric line current (N3-SYLC in short) is proposed for correcting 3rd order spherical aberration of round lenses. N3-SYLC can be realized without using magnetic materials, which makes it free of the problems of hysteresis, inhomogeneity and saturation. We investigate theoretically the basic properties of an N3-SYLC configuration which can in principle be realized by simple wires. By optimizing the parameters of a system with beam energy of 5.5keV, the required excitation current for correcting 3rd order spherical aberration coefficient of 400 mm is less than 1AT, and the residual higher order aberrations can be kept sufficiently small to obtain beam size of less than 1 nm for initial slopes up to 5 mrad. Copyright © 2015 Elsevier B.V. All rights reserved.

  3. Imaging single atoms using secondary electrons with an aberration-corrected electron microscope.

    Science.gov (United States)

    Zhu, Y; Inada, H; Nakamura, K; Wall, J

    2009-10-01

    Aberration correction has embarked on a new frontier in electron microscopy by overcoming the limitations of conventional round lenses, providing sub-angstrom-sized probes. However, improvement of spatial resolution using aberration correction so far has been limited to the use of transmitted electrons both in scanning and stationary mode, with an improvement of 20-40% (refs 3-8). In contrast, advances in the spatial resolution of scanning electron microscopes (SEMs), which are by far the most widely used instrument for surface imaging at the micrometre-nanometre scale, have been stagnant, despite several recent efforts. Here, we report a new SEM, with aberration correction, able to image single atoms by detecting electrons emerging from its surface as a result of interaction with the small probe. The spatial resolution achieved represents a fourfold improvement over the best-reported resolution in any SEM (refs 10-12). Furthermore, we can simultaneously probe the sample through its entire thickness with transmitted electrons. This ability is significant because it permits the selective visualization of bulk atoms and surface ones, beyond a traditional two-dimensional projection in transmission electron microscopy. It has the potential to revolutionize the field of microscopy and imaging, thereby opening the door to a wide range of applications, especially when combined with simultaneous nanoprobe spectroscopy.

  4. Influence of Misalignment on High-Order Aberration Correction for Normal Human Eyes

    Science.gov (United States)

    Zhao, Hao-Xin; Xu, Bing; Xue, Li-Xia; Dai, Yun; Liu, Qian; Rao, Xue-Jun

    2008-04-01

    Although a compensation device can correct aberrations of human eyes, the effect will be degraded by its misalignment, especially for high-order aberration correction. We calculate the positioning tolerance of correction device for high-order aberrations, and within what degree the correcting effect is better than low-order aberration (defocus and astigmatism) correction. With fixed certain misalignment within the positioning tolerance, we calculate the residual wavefront rms aberration of the first-6 to first-35 terms along with the 3rd-5th terms of aberrations corrected, and the combined first-13 terms of aberrations are also studied under the same quantity of misalignment. However, the correction effect of high-order aberrations does not meliorate along with the increase of the high-order terms under some misalignment, moreover, some simple combined terms correction can achieve similar result as complex combinations. These results suggest that it is unnecessary to correct too much the terms of high-order aberrations which are difficult to accomplish in practice, and gives confidence to correct high-order aberrations out of the laboratory.

  5. Influence of Misalignment on High-Order Aberration Correction for Normal Human Eyes

    International Nuclear Information System (INIS)

    Hao-Xin, Zhao; Bing, Xu; Li-Xia, Xue; Yun, Dai; Qian, Liu; Xue-Jun, Rao

    2008-01-01

    Although a compensation device can correct aberrations of human eyes, the effect will be degraded by its misalignment, especially for high-order aberration correction. We calculate the positioning tolerance of correction device for high-order aberrations, and within what degree the correcting effect is better than low-order aberration (defocus and astigmatism) correction. With fixed certain misalignment within the positioning tolerance, we calculate the residual wavefront rms aberration of the first-6 to first-35 terms along with the 3rd-5th terms of aberrations corrected, and the combined first-13 terms of aberrations are also studied under the same quantity of misalignment. However, the correction effect of high-order aberrations does not meliorate along with the increase of the high-order terms under some misalignment, moreover, some simple combined terms correction can achieve similar result as complex combinations. These results suggest that it is unnecessary to correct too much the terms of high-order aberrations which are difficult to accomplish in practice, and gives confidence to correct high-order aberrations out of the laboratory

  6. Image transfer with spatial coherence for aberration corrected transmission electron microscopes

    International Nuclear Information System (INIS)

    Hosokawa, Fumio; Sawada, Hidetaka; Shinkawa, Takao; Sannomiya, Takumi

    2016-01-01

    The formula of spatial coherence involving an aberration up to six-fold astigmatism is derived for aberration-corrected transmission electron microscopy. Transfer functions for linear imaging are calculated using the newly derived formula with several residual aberrations. Depending on the symmetry and origin of an aberration, the calculated transfer function shows characteristic symmetries. The aberrations that originate from the field’s components, having uniformity along the z direction, namely, the n-fold astigmatism, show rotational symmetric damping of the coherence. The aberrations that originate from the field’s derivatives with respect to z, such as coma, star, and three lobe, show non-rotational symmetric damping. It is confirmed that the odd-symmetric wave aberrations have influences on the attenuation of an image via spatial coherence. Examples of image simulations of haemoglobin and Si [211] are shown by using the spatial coherence for an aberration-corrected electron microscope. - Highlights: • The formula of partial coherence for aberration corrected TEM is derived. • Transfer functions are calculated with several residual aberrations. • The calculated transfer function shows the characteristic damping. • The odd-symmetric wave aberrations can cause the attenuation of image via coherence. • The examples of aberration corrected TEM image simulations are shown.

  7. Image transfer with spatial coherence for aberration corrected transmission electron microscopes

    Energy Technology Data Exchange (ETDEWEB)

    Hosokawa, Fumio, E-mail: hosokawa@bio-net.co.jp [BioNet Ltd., 2-3-28 Nishikityo, Tachikwa, Tokyo (Japan); Tokyo Institute of Technology, 4259 Nagatsuta, Midoriku, Yokohama 226-8503 (Japan); Sawada, Hidetaka [JEOL (UK) Ltd., JEOL House, Silver Court, Watchmead, Welwyn Garden City, Herts AL7 1LT (United Kingdom); Shinkawa, Takao [BioNet Ltd., 2-3-28 Nishikityo, Tachikwa, Tokyo (Japan); Sannomiya, Takumi [Tokyo Institute of Technology, 4259 Nagatsuta, Midoriku, Yokohama 226-8503 (Japan)

    2016-08-15

    The formula of spatial coherence involving an aberration up to six-fold astigmatism is derived for aberration-corrected transmission electron microscopy. Transfer functions for linear imaging are calculated using the newly derived formula with several residual aberrations. Depending on the symmetry and origin of an aberration, the calculated transfer function shows characteristic symmetries. The aberrations that originate from the field’s components, having uniformity along the z direction, namely, the n-fold astigmatism, show rotational symmetric damping of the coherence. The aberrations that originate from the field’s derivatives with respect to z, such as coma, star, and three lobe, show non-rotational symmetric damping. It is confirmed that the odd-symmetric wave aberrations have influences on the attenuation of an image via spatial coherence. Examples of image simulations of haemoglobin and Si [211] are shown by using the spatial coherence for an aberration-corrected electron microscope. - Highlights: • The formula of partial coherence for aberration corrected TEM is derived. • Transfer functions are calculated with several residual aberrations. • The calculated transfer function shows the characteristic damping. • The odd-symmetric wave aberrations can cause the attenuation of image via coherence. • The examples of aberration corrected TEM image simulations are shown.

  8. High-resolution TEM and the application of direct and indirect aberration correction

    DEFF Research Database (Denmark)

    Hetherington, Crispin J.D.; Chang, Lan-Yun Shery; Haigh, Sarah

    2008-01-01

    Aberration correction leads to a substantial improvement in the directly interpretable resolution of transmission electron microscopes. Correction of the aberrations has been achieved electron-optically through a hexapole-based corrector and also indirectly by computational analysis of a focal or...

  9. Statistical estimation of ultrasonic propagation path parameters for aberration correction.

    Science.gov (United States)

    Waag, Robert C; Astheimer, Jeffrey P

    2005-05-01

    Parameters in a linear filter model for ultrasonic propagation are found using statistical estimation. The model uses an inhomogeneous-medium Green's function that is decomposed into a homogeneous-transmission term and a path-dependent aberration term. Power and cross-power spectra of random-medium scattering are estimated over the frequency band of the transmit-receive system by using closely situated scattering volumes. The frequency-domain magnitude of the aberration is obtained from a normalization of the power spectrum. The corresponding phase is reconstructed from cross-power spectra of subaperture signals at adjacent receive positions by a recursion. The subapertures constrain the receive sensitivity pattern to eliminate measurement system phase contributions. The recursion uses a Laplacian-based algorithm to obtain phase from phase differences. Pulse-echo waveforms were acquired from a point reflector and a tissue-like scattering phantom through a tissue-mimicking aberration path from neighboring volumes having essentially the same aberration path. Propagation path aberration parameters calculated from the measurements of random scattering through the aberration phantom agree with corresponding parameters calculated for the same aberrator and array position by using echoes from the point reflector. The results indicate the approach describes, in addition to time shifts, waveform amplitude and shape changes produced by propagation through distributed aberration under realistic conditions.

  10. Sextupole system for the correction of spherical aberration

    Science.gov (United States)

    Crewe, A.V.; Kopf, D.A.

    In an electron beam device in which an electron beam is developed and then focused by a lens to a particular spot, there is provided a means for eliminating spherical aberration. A sextupole electromagnetic lens is positioned between two focusing lenses. The interaction of the sextupole with the beam compensates for spherical aberration. (GHT)

  11. Correcting the wavefront aberration of membrane mirror based on liquid crystal spatial light modulator

    Science.gov (United States)

    Yang, Bin; Wei, Yin; Chen, Xinhua; Tang, Minxue

    2014-11-01

    Membrane mirror with flexible polymer film substrate is a new-concept ultra lightweight mirror for space applications. Compared with traditional mirrors, membrane mirror has the advantages of lightweight, folding and deployable, low cost and etc. Due to the surface shape of flexible membrane mirror is easy to deviate from the design surface shape, it will bring wavefront aberration to the optical system. In order to solve this problem, a method of membrane mirror wavefront aberration correction based on the liquid crystal spatial light modulator (LCSLM) will be studied in this paper. The wavefront aberration correction principle of LCSLM is described and the phase modulation property of a LCSLM is measured and analyzed firstly. Then the membrane mirror wavefront aberration correction system is designed and established according to the optical properties of a membrane mirror. The LCSLM and a Hartmann-Shack sensor are used as a wavefront corrector and a wavefront detector, respectively. The detected wavefront aberration is calculated and converted into voltage value on LCSLM for the mirror wavefront aberration correction by programming in Matlab. When in experiment, the wavefront aberration of a glass plane mirror with a diameter of 70 mm is measured and corrected for verifying the feasibility of the experiment system and the correctness of the program. The PV value and RMS value of distorted wavefront are reduced and near diffraction limited optical performance is achieved. On this basis, the wavefront aberration of the aperture center Φ25 mm in a membrane mirror with a diameter of 200 mm is corrected and the errors are analyzed. It provides a means of correcting the wavefront aberration of membrane mirror.

  12. Angstrom analysis with dynamic in-situ aberration corrected electron microscopy

    International Nuclear Information System (INIS)

    Gai, P L; Boyes, E D

    2010-01-01

    Following the pioneering development of atomic resolution in-situ environmental TEM (ETEM) for direct probing of gas-solid reactions, recent developments are presented of dynamic real time in-situ studies at the Angstrom level in an aberration corrected electron microscope. The in-situ data from Pt-Pd nanoparticles on carbon with the corresponding FFT/optical diffractogram (OD) illustrate an achieved resolution of 0 C and higher, in a double aberration corrected JEOL 2200 FS TEM/STEM employing a wider gap objective pole piece and gas tolerant TMP column pumping system. Direct observations of dynamic biofuel catalysts under controlled calcinations conditions and quantified with catalytic reactivity and physico-chemical studies show the benefits in-situ aberration correction in unveiling the evolution of surface active sites necessary for the development efficient heterogeneous catalysts. The new results open up opportunities for dynamic studies of materials in an aberration corrected environment and direct future development activities.

  13. Hartmann characterization of the PEEM-3 aberration-corrected X-ray photoemission electron microscope.

    Science.gov (United States)

    Scholl, A; Marcus, M A; Doran, A; Nasiatka, J R; Young, A T; MacDowell, A A; Streubel, R; Kent, N; Feng, J; Wan, W; Padmore, H A

    2018-05-01

    Aberration correction by an electron mirror dramatically improves the spatial resolution and transmission of photoemission electron microscopes. We will review the performance of the recently installed aberration corrector of the X-ray Photoemission Electron Microscope PEEM-3 and show a large improvement in the efficiency of the electron optics. Hartmann testing is introduced as a quantitative method to measure the geometrical aberrations of a cathode lens electron microscope. We find that aberration correction leads to an order of magnitude reduction of the spherical aberrations, suggesting that a spatial resolution of below 100 nm is possible at 100% transmission of the optics when using x-rays. We demonstrate this improved performance by imaging test patterns employing element and magnetic contrast. Published by Elsevier B.V.

  14. Comparison of wavefront aberrations under cycloplegic, scotopic and photopic conditions using WaveScan

    Directory of Open Access Journals (Sweden)

    Rong Fan

    2012-04-01

    Full Text Available PURPOSE: To evaluate the differences of wavefront aberrations under cycloplegic, scotopic and photopic conditions. METHODS: A total of 174 eyes of 105 patients were measured using the wavefront sensor (WaveScan® 3.62 under different pupil conditions: cycloplegic 8.58 ± 0.54 mm (6.4 mm - 9.5 mm, scotopic 7.53 ± 0.69 mm (5.7 mm - 9.1 mm and photopic 6.08 ± 1.14 mm (4.1 mm - 8.8 mm. The pupil diameter, standard Zernike coefficients, root mean square of higher-order aberrations and dominant aberrations were compared between cycloplegic and scotopic conditions, and between scotopic and photopic conditions. RESULTS: The pupil diameter was 7.53 ± 0.69 mm under the scotopic condition, which reached the requirement of about 6.5 mm optical zone design in the wavefront-guided surgery and prevented measurement error due to the pupil centroid shift caused by mydriatics. Pharmacological pupil dilation induced increase of standard Zernike coefficients Z3-3, Z4(0 and Z5-5. The higher-order aberrations, third-order aberration, fourth-order aberration, fifth-order aberration, sixth-order aberration, and spherical aberration increased statistically significantly, compared to the scotopic condition (P<0.010. When the scotopic condition shifted to the photopic condition, the standard Zernike coefficients Z4(0, Z4², Z6-4, Z6-2, Z6² decreased and all the higher-order aberrations decreased statistically significantly (P<0.010, demonstrating that accommodative miosis can significantly improve vision under the photopic condition. Under the three conditions, the vertical coma aberration appears the most frequently within the dominant aberrations without significant effect by pupil size variance, and the proportion of spherical aberrations decreased with the decrease of the pupil size. CONCLUSIONS: The wavefront aberrations are significantly different under cycloplegic, scotopic and photopic conditions. Using the wavefront sensor (VISX WaveScan to measure scotopic

  15. Chromatic aberrations correction for imaging spectrometer based on acousto-optic tunable filter with two transducers.

    Science.gov (United States)

    Zhao, Huijie; Wang, Ziye; Jia, Guorui; Zhang, Ying; Xu, Zefu

    2017-10-02

    The acousto-optic tunable filter (AOTF) with wide wavelength range and high spectral resolution has long crystal and two transducers. A longer crystal length leads to a bigger chromatic focal shift and the double-transducer arrangement induces angular mutation in diffracted beam, which increase difficulty in longitudinal and lateral chromatic aberration correction respectively. In this study, the two chromatic aberrations are analyzed quantitatively based on an AOTF optical model and a novel catadioptric dual-path configuration is proposed to correct both the chromatic aberrations. The test results exhibit effectiveness of the optical configuration for this type of AOTF-based imaging spectrometer.

  16. Deep Tissue Wavefront Estimation for Sensorless Aberration Correction

    Directory of Open Access Journals (Sweden)

    Ibrahimovic Emina

    2015-01-01

    Full Text Available The multiple light scattering in biological tissues limits the measurement depth for traditional wavefront sensor. The attenuated ballistic light and the background noise caused by the diffuse light give low signal to noise ratio for wavefront measurement. To overcome this issue, we introduced a wavefront estimation method based on a ray tracing algorithm to overcome this issue. With the knowledge of the refractive index of the medium, the wavefront is estimated by calculating optical path length of rays from the target inside of the samples. This method can provide not only the information of spherical aberration from the refractive-index mismatch between the medium and biological sample but also other aberrations caused by the irregular interface between them. Simulations based on different configurations are demonstrated in this paper.

  17. Axial geometrical aberration correction up to 5th order with N-SYLC.

    Science.gov (United States)

    Hoque, Shahedul; Ito, Hiroyuki; Takaoka, Akio; Nishi, Ryuji

    2017-11-01

    We present N-SYLC (N-fold symmetric line currents) models to correct 5th order axial geometrical aberrations in electron microscopes. In our previous paper, we showed that 3rd order spherical aberration can be corrected by 3-SYLC doublet. After that, mainly the 5th order aberrations remain to limit the resolution. In this paper, we extend the doublet to quadruplet models also including octupole and dodecapole fields for correcting these higher order aberrations, without introducing any new unwanted ones. We prove the validity of our models by analytical calculations. Also by computer simulations, we show that for beam energy of 5keV and initial angle 10mrad at the corrector object plane, beam size of less than 0.5nm is achieved at the corrector image plane. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Effects of SMILE and Trans-PRK on corneal higher order aberrations after myopic correction

    Directory of Open Access Journals (Sweden)

    Jiao Zhao

    2018-02-01

    Full Text Available AIM:To observe the effects of small incision lenticule extraction(SMILEand trans-epithelial photorefractive keratectomy(Trans-PRKon corneal horizontal coma, vertical coma, and spherical aberration and total higher order aberrations after refractive correction for myopia. METHODS: This was a prospective non-randomized cohort study. The cohort included 40 patients(80 eyeswith myopia, who received refraction correction surgery from December 2016 to February 2017 in Leshan Ophthalmic Center. Twenty patients(40 eyesreceived SMILE surgery and the other 20 patients(40 eyesreceived Trans-PRK surgery. Corneal aberrations were determined by a high-resolution Pentacam Scheimpflug camera before the surgery and at 1 and 3mo after the operation. Statistical analyses were performed using analysis of variance of repeated measures. RESULTS: At 1 and 3mo post-operation, the uncorrected visual acuity in both groups was better than or equal to the preoperative best corrected visual acuity. The preoperative corneal aberrations showed no significant difference between the two groups(P>0.05. Significantly higher aberration was found after the surgery in both groups(PP>0.05. Post-operation, horizontal and vertical coma had no significant difference between the two groups(P>0.05, while SMILE group showed lower spherical aberration and lower total higher order aberration than Trans-PRK group(PCONCLUSION: Both SMILE and Trans-PRK increase corneal aberration and their effects on horizontal and vertical coma are similar. However, SMILE has a minor influence on spherical aberration and total high order aberration than Trans-PRK.

  19. Chromatic aberration correction: an enhancement to the calibration of low-cost digital dermoscopes.

    Science.gov (United States)

    Wighton, Paul; Lee, Tim K; Lui, Harvey; McLean, David; Atkins, M Stella

    2011-08-01

    We present a method for calibrating low-cost digital dermoscopes that corrects for color and inconsistent lighting and also corrects for chromatic aberration. Chromatic aberration is a form of radial distortion that often occurs in inexpensive digital dermoscopes and creates red and blue halo-like effects on edges. Being radial in nature, distortions due to chromatic aberration are not constant across the image, but rather vary in both magnitude and direction. As a result, distortions are not only visually distracting but could also mislead automated characterization techniques. Two low-cost dermoscopes, based on different consumer-grade cameras, were tested. Color is corrected by imaging a reference and applying singular value decomposition to determine the transformation required to ensure accurate color reproduction. Lighting is corrected by imaging a uniform surface and creating lighting correction maps. Chromatic aberration is corrected using a second-order radial distortion model. Our results for color and lighting calibration are consistent with previously published results, while distortions due to chromatic aberration can be reduced by 42-47% in the two systems considered. The disadvantages of inexpensive dermoscopy can be quickly substantially mitigated with a suitable calibration procedure. © 2011 John Wiley & Sons A/S.

  20. Research on the Phase Aberration Correction with a Deformable Mirror Controlled by a Genetic Algorithm

    International Nuclear Information System (INIS)

    Yang, P; Hu, S J; Chen, S Q; Yang, W; Xu, B; Jiang, W H

    2006-01-01

    In order to improve laser beam quality, a real number encoding genetic algorithm based on adaptive optics technology was presented. This algorithm was applied to control a 19-channel deformable mirror to correct phase aberration in laser beam. It is known that when traditional adaptive optics system is used to correct laser beam wave-front phase aberration, a precondition is to measure the phase aberration information in the laser beam. However, using genetic algorithms, there is no necessary to know the phase aberration information in the laser beam beforehand. The only parameter need to know is the Light intensity behind the pinhole on the focal plane. This parameter was used as the fitness function for the genetic algorithm. Simulation results show that the optimal shape of the 19-channel deformable mirror applied to correct the phase aberration can be ascertained. The peak light intensity was improved by a factor of 21, and the encircled energy strehl ratio was increased to 0.34 from 0.02 as the phase aberration was corrected with this technique

  1. Automated aberration correction of arbitrary laser modes in high numerical aperture systems

    OpenAIRE

    Hering, Julian; Waller, Erik H.; Freymann, Georg von

    2016-01-01

    Controlling the point-spread-function in three-dimensional laser lithography is crucial for fabricating structures with highest definition and resolution. In contrast to microscopy, aberrations have to be physically corrected prior to writing, to create well defined doughnut modes, bottlebeams or multi foci modes. We report on a modified Gerchberg-Saxton algorithm for spatial-light-modulator based automated aberration compensation to optimize arbitrary laser-modes in a high numerical aperture...

  2. Effect of correction of aberration dynamics on chaos in human ocular accommodation.

    Science.gov (United States)

    Hampson, Karen M; Cufflin, Matthew P; Mallen, Edward A H

    2013-11-15

    We used adaptive optics to determine the effect of monochromatic aberration dynamics on the level of chaos in the accommodation control system. Four participants viewed a stationary target while the dynamics of their aberrations were either left uncorrected, defocus was corrected, or all aberrations except defocus were corrected. Chaos theory analysis was used to discern changes in the accommodative microfluctuations. We found a statistically significant reduction in the chaotic nature of the accommodation microfluctuations during correction of defocus, but not when all aberrations except defocus were corrected. The Lyapunov exponent decreased from 0.71 ± 0.07 D/s (baseline) to 0.55 ± 0.03 D/s (correction of defocus fluctuations). As the reduction of chaos in physiological signals is indicative of stress to the system, the results indicate that for the participants included in this study, fluctuations in defocus have a more profound effect than those of the other aberrations. There were no changes in the power spectrum between experimental conditions. Hence chaos theory analysis is a more subtle marker of changes in the accommodation control system and will be of value in the study of myopia onset and progression.

  3. Correcting for color crosstalk and chromatic aberration in multicolor particle shadow velocimetry

    International Nuclear Information System (INIS)

    McPhail, M J; Fontaine, A A; Krane, M H; Goss, L; Crafton, J

    2015-01-01

    Color crosstalk and chromatic aberration can bias estimates of fluid velocity measured by color particle shadow velocimetry (CPSV), using multicolor illumination and a color camera. This article describes corrections to remove these bias errors, and their evaluation. Color crosstalk removal is demonstrated with linear unmixing. It is also shown that chromatic aberrations may be removed using either scale calibration, or by processing an image illuminated by all colors simultaneously. CPSV measurements of a fully developed turbulent pipe flow of glycerin were conducted. Corrected velocity statistics from these measurements were compared to both single-color PSV and LDV measurements and showed excellent agreement to fourth-order, to well into the viscous sublayer. Recommendations for practical assessment and correction of color aberration and color crosstalk are discussed. (paper)

  4. A new aberration-corrected, energy-filtered LEEM/PEEM instrument. I. Principles and design

    International Nuclear Information System (INIS)

    Tromp, R.M.; Hannon, J.B.; Ellis, A.W.; Wan, W.; Berghaus, A.; Schaff, O.

    2010-01-01

    We describe a new design for an aberration-corrected low energy electron microscope (LEEM) and photo electron emission microscope (PEEM), equipped with an in-line electron energy filter. The chromatic and spherical aberrations of the objective lens are corrected with an electrostatic electron mirror that provides independent control over the chromatic and spherical aberration coefficients C c and C 3 , as well as the mirror focal length, to match and correct the aberrations of the objective lens. For LEEM (PEEM) the theoretical resolution is calculated to be ∼1.5 nm (∼4 nm). Unlike previous designs, this instrument makes use of two magnetic prism arrays to guide the electron beam from the sample to the electron mirror, removing chromatic dispersion in front of the mirror by symmetry. The aberration correction optics was retrofitted to an uncorrected instrument with a base resolution of 4.1 nm in LEEM. Initial results in LEEM show an improvement in resolution to ∼2 nm.

  5. Nonlinear adaptive optics: aberration correction in three photon fluorescence microscopy for mouse brain imaging

    Science.gov (United States)

    Sinefeld, David; Paudel, Hari P.; Wang, Tianyu; Wang, Mengran; Ouzounov, Dimitre G.; Bifano, Thomas G.; Xu, Chris

    2017-02-01

    Multiphoton fluorescence microscopy is a well-established technique for deep-tissue imaging with subcellular resolution. Three-photon microscopy (3PM) when combined with long wavelength excitation was shown to allow deeper imaging than two-photon microscopy (2PM) in biological tissues, such as mouse brain, because out-of-focus background light can be further reduced due to the higher order nonlinear excitation. As was demonstrated in 2PM systems, imaging depth and resolution can be improved by aberration correction using adaptive optics (AO) techniques which are based on shaping the scanning beam using a spatial light modulator (SLM). In this way, it is possible to compensate for tissue low order aberration and to some extent, to compensate for tissue scattering. Here, we present a 3PM AO microscopy system for brain imaging. Soliton self-frequency shift is used to create a femtosecond source at 1675 nm and a microelectromechanical (MEMS) SLM serves as the wavefront shaping device. We perturb the 1020 segment SLM using a modified nonlinear version of three-point phase shifting interferometry. The nonlinearity of the fluorescence signal used for feedback ensures that the signal is increasing when the spot size decreases, allowing compensation of phase errors in an iterative optimization process without direct phase measurement. We compare the performance for different orders of nonlinear feedback, showing an exponential growth in signal improvement as the nonlinear order increases. We demonstrate the impact of the method by applying the 3PM AO system for in-vivo mouse brain imaging, showing improvement in signal at 1-mm depth inside the brain.

  6. Correction of chromatic and geometric aberrations using sextupoles and octupoles

    International Nuclear Information System (INIS)

    Colton, E.

    1978-01-01

    The procedure for applying some chromatic corrections to a final transport line, neglecting space charge, utilizing the method suggested by Brown is described. The possibility of including octupoles into a point-to-point triplet system, as outlined by Fenster is studied. Positive results were obtained in both cases: (i) using 2 + I correcting sections with two pairs of non-interlaced sextupoles increased the fraction of beam with ΔP/P = 1% onto a 0.1 cm radius target by more than a factor of 1.75; (ii) six octupoles placed into a point-to-point triplet system increased the fraction of a full emittance ΔP/P = 0% beam striking a 0.1 cm radius target by a factor of 2.5

  7. Present status and future prospects of spherical aberration corrected TEM/STEM for study of nanomaterials

    International Nuclear Information System (INIS)

    Tanaka, Nobuo

    2008-01-01

    The present status of Cs-corrected TEM/STEM is described from the viewpoint of the observation of nanomaterials. Characteristic features in TEM and STEM are explained using the experimental data obtained by our group and other research groups. Cs correction up to the 3rd-order aberration of an objective lens has already been established and research interest is focused on correcting the 5th-order spherical aberration and the chromatic aberration in combination with the development of a monochromator below an electron gun for smaller point-to-point resolution in optics. Another fundamental area of interest is the limitation of TEM and STEM resolution from the viewpoint of the scattering of electrons in crystals. The minimum size of the exit-wave function below samples undergoing TEM imaging is determined from the calculation of scattering around related atomic columns in the crystals. STEM does not have this limitation because the resolution is, in principle, determined by the probe size. One of the future prospects of Cs-corrected TEM/STEM is the possibility of extending the space around the sample holder by correcting the chromatic and spherical aberrations. This wider space will contribute to the ease of performing in situ experiments and various combinations of TEM and other analysis methods. High-resolution, in situ dynamic and 3D observations/analysis are the most important keywords in the next decade of high-resolution electron microscopy. (topical review)

  8. A lateral chromatic aberration correction system for ultrahigh-definition color video camera

    Science.gov (United States)

    Yamashita, Takayuki; Shimamoto, Hiroshi; Funatsu, Ryohei; Mitani, Kohji; Nojiri, Yuji

    2006-02-01

    We have developed color camera for an 8k x 4k-pixel ultrahigh-definition video system, which is called Super Hi- Vision, with a 5x zoom lens and a signal-processing system incorporating a function for real-time lateral chromatic aberration correction. The chromatic aberration of the lens degrades color image resolution. So in order to develop a compact zoom lens consistent with ultrahigh-resolution characteristics, we incorporated a real-time correction function in the signal-processing system. The signal-processing system has eight memory tables to store the correction data at eight focal length points on the blue and red channels. When the focal length data is inputted from the lens control units, the relevant correction data are interpolated from two of eights correction data tables. This system performs geometrical conversion on both channels using this correction data. This paper describes that the correction function can successfully reduce the lateral chromatic aberration, to an amount small enough to ensure the desired image resolution was achieved over the entire range of the lens in real time.

  9. Spherical aberration correction with an in-lens N-fold symmetric line currents model.

    Science.gov (United States)

    Hoque, Shahedul; Ito, Hiroyuki; Nishi, Ryuji

    2018-04-01

    In our previous works, we have proposed N-SYLC (N-fold symmetric line currents) models for aberration correction. In this paper, we propose "in-lens N-SYLC" model, where N-SYLC overlaps rotationally symmetric lens. Such overlap is possible because N-SYLC is free of magnetic materials. We analytically prove that, if certain parameters of the model are optimized, an in-lens 3-SYLC (N = 3) doublet can correct 3rd order spherical aberration. By computer simulation, we show that the required excitation current for correction is less than 0.25 AT for beam energy 5 keV, and the beam size after correction is smaller than 1 nm at the corrector image plane for initial slope less than 4 mrad. Copyright © 2018 Elsevier B.V. All rights reserved.

  10. Aberration-corrected imaging of active sites on industrial catalyst nanoparticles

    DEFF Research Database (Denmark)

    Gontard, Lionel Cervera; Chang, L-Y; Hetherington, CJD

    2007-01-01

    Picture perfect: Information about the local topologies of active sites on commercial nanoparticles can be gained with atomic resolution through spherical-aberration-corrected transmission electron microscopy (TEM). A powder of Pt nanoparticles on carbon black was examined with two advanced TEM t...

  11. A new aberration-corrected, energy-filtered LEEM/PEEM instrument II. Operation and results

    International Nuclear Information System (INIS)

    Tromp, R.M.; Hannon, J.B.; Wan, W.; Berghaus, A.; Schaff, O.

    2013-01-01

    In Part I we described a new design for an aberration-corrected Low Energy Electron Microscope (LEEM) and Photo Electron Emission Microscope (PEEM) equipped with an in-line electron energy filter. The chromatic and spherical aberrations of the objective lens are corrected with an electrostatic electron mirror that provides independent control of the chromatic and spherical aberration coefficients C c and C 3 , as well as the mirror focal length. In this Part II we discuss details of microscope operation, how the microscope is set up in a systematic fashion, and we present typical results. - Highlights: ► The C c and C 3 aberrations of a LEEM/PEEM instrument are corrected with an electrostatic electron mirror. ► The mirror provides independent control over C c , C 3 and focal length in close agreement with theory. ► A detailed alignment procedure for the corrected microscope is given. ► Novel methods to measure C c and C 3 of the objective lens and the mirror are presented. ► We demonstrate a record spatial resolution of 2 nm

  12. The application of aberration-corrected electron microscopy to the characterization of gold-based catalysts

    Science.gov (United States)

    Herzing, Andrew A.

    Electron microscopy has long been used to study the morphology of heterogeneous catalysts. Recent advances in electron optics now allow for the correction of the inherent spherical aberration (Cs) produced by the objective lens in the scanning transmission electron microscope (STEM, resulting in a significantly improved spatial resolution as well as the ability to use a much larger probe-current than was previously possible. In this thesis, the combination of high-angle annular dark-field (HAADF) imaging and microanalysis by x-ray energy dispersive spectroscopy (XEDS) in an aberration-corrected STEM has been applied for the first time to the characterization of gold-based heterogeneous catalysts. Multi-variate statistical analysis (MSA) has been employed in order to further improve the STEM-XEDS spectrum image data acquired with this technique. In addition, supplemental analysis using electron-energy loss spectroscopy (EELS) and energy-filtered transmission electron microscopy (EFTEM) in an aberration-corrected instrument has also been attempted. These techniques have proven extremely valuable in providing complimentary information to more traditional catalyst characterization techniques such as x-ray photoelectron spectroscopy and x-ray diffraction in four specific problems relating to catalysis. Firstly, the atomic-scale resolution of Cs-corrected HAADF imaging has been utilized to study Au/FeOx catalysts in order to determine the size and structure of the Au clusters present on the support surface. It was discovered that, while both inactive and active catalysts for low-temperature CO oxidation contained large Au particles (> 5 nm) and individual Au atoms, the active catalyst also contained sub-nm clusters comprised of only a few Au atoms. Secondly, novel CeO2 support materials for Au and Au-Pd catalysts were synthesized by precipitation with supercritical CO2. These supports were found to produce significantly more active catalysts than those based on CeO2

  13. Chromatic Aberration Correction for Atomic Resolution TEM Imaging from 20 to 80 kV.

    Science.gov (United States)

    Linck, Martin; Hartel, Peter; Uhlemann, Stephan; Kahl, Frank; Müller, Heiko; Zach, Joachim; Haider, Max; Niestadt, Marcel; Bischoff, Maarten; Biskupek, Johannes; Lee, Zhongbo; Lehnert, Tibor; Börrnert, Felix; Rose, Harald; Kaiser, Ute

    2016-08-12

    Atomic resolution in transmission electron microscopy of thin and light-atom materials requires a rigorous reduction of the beam energy to reduce knockon damage. However, at the same time, the chromatic aberration deteriorates the resolution of the TEM image dramatically. Within the framework of the SALVE project, we introduce a newly developed C_{c}/C_{s} corrector that is capable of correcting both the chromatic and the spherical aberration in the range of accelerating voltages from 20 to 80 kV. The corrector allows correcting axial aberrations up to fifth order as well as the dominating off-axial aberrations. Over the entire voltage range, optimum phase-contrast imaging conditions for weak signals from light atoms can be adjusted for an optical aperture of at least 55 mrad. The information transfer within this aperture is no longer limited by chromatic aberrations. We demonstrate the performance of the microscope using the examples of 30 kV phase-contrast TEM images of graphene and molybdenum disulfide, showing unprecedented contrast and resolution that matches image calculations.

  14. Magnitude of speed of sound aberration corrections for ultrasound image guided radiotherapy for prostate and other anatomical sites

    International Nuclear Information System (INIS)

    Fontanarosa, Davide; Meer, Skadi van der; Bloemen-van Gurp, Esther; Stroian, Gabriela; Verhaegen, Frank

    2012-01-01

    Purpose: The purpose of this work is to assess the magnitude of speed of sound (SOS) aberrations in three-dimensional ultrasound (US) imaging systems in image guided radiotherapy. The discrepancy between the fixed SOS value of 1540 m/s assumed by US systems in human soft tissues and its actual nonhomogeneous distribution in patients produces small but systematic errors of up to a few millimeters in the positions of scanned structures. Methods: A correction, provided by a previously published density-based algorithm, was applied to a set of five prostate, five liver, and five breast cancer patients. The shifts of the centroids of target structures and the change in shape were evaluated. Results: After the correction the prostate cases showed shifts up to 3.6 mm toward the US probe, which may explain largely the reported positioning discrepancies in the literature on US systems versus other imaging modalities. Liver cases showed the largest changes in volume of the organ, up to almost 9%, and shifts of the centroids up to more than 6 mm either away or toward the US probe. Breast images showed systematic small shifts of the centroids toward the US probe with a maximum magnitude of 1.3 mm. Conclusions: The applied correction in prostate and liver cancer patients shows positioning errors of several mm due to SOS aberration; the errors are smaller in breast cancer cases, but possibly becoming more important when breast tissue thickness increases.

  15. An aberration corrected photoemission electron microscope at the advanced light source

    International Nuclear Information System (INIS)

    Feng, J.; MacDowell, A.A.; Duarte, R.; Doran, A.; Forest, E.; Kelez, N.; Marcus, M.; Munson, D.; Padmore, H.; Petermann, K.; Raoux, S.; Robin, D.; Scholl, A.; Schlueter, R.; Schmid, P.; Stohr, J.; Wan, W.; Wei, D.H.; Wu, Y.

    2003-01-01

    Design of a new aberration corrected Photoemission electron microscope PEEM3 at the Advanced Light Source is outlined. PEEM3 will be installed on an elliptically polarized undulator beamline and will be used for the study of complex materials at high spatial and spectral resolution. The critical components of PEEM3 are the electron mirror aberration corrector and aberration-free magnetic beam separator. The models to calculate the optical properties of the electron mirror are discussed. The goal of the PEEM3 project is to achieve the highest possible transmission of the system at resolutions comparable to our present PEEM2 system (50 nm) and to enable significantly higher resolution, albeit at the sacrifice of intensity. We have left open the possibility to add an energy filter at a later date, if it becomes necessary driven by scientific need to improve the resolution further

  16. The objective lens of the electron microscope with correction of spherical and axial chromatic aberrations.

    Science.gov (United States)

    Bimurzaev, S B; Aldiyarov, N U; Yakushev, E M

    2017-10-01

    The paper describes the principle of operation of a relatively simple aberration corrector for the transmission electron microscope objective lens. The electron-optical system of the aberration corrector consists of the two main elements: an electrostatic mirror with rotational symmetry and a magnetic deflector formed by the round-shaped magnetic poles. The corrector operation is demonstrated by calculations on the example of correction of basic aberrations of the well-known objective lens with a bell-shaped distribution of the axial magnetic field. Two of the simplest versions of the corrector are considered: a corrector with a two-electrode electrostatic mirror and a corrector with a three-electrode electrostatic mirror. It is shown that using the two-electrode mirror one can eliminate either spherical or chromatic aberration of the objective lens, without changing the value of its linear magnification. Using a three-electrode mirror, it is possible to eliminate spherical and chromatic aberrations of the objective lens simultaneously, which is especially important in designing electron microscopes with extremely high resolution. © The Author 2017. Published by Oxford University Press on behalf of The Japanese Society of Microscopy. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  17. Seeing atoms with aberration-corrected sub-Angstroem electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    O' Keefe, Michael A. [Materials Science Division, Lawrence Berkeley National Laboratory, National Center for Electron Microscopy, 2R0200, 1 Cyclotron Road, Berkeley, CA 94720-8197 (United States)], E-mail: sub-Angstrom@comcast.net

    2008-02-15

    High-resolution electron microscopy is able to provide atomic-level characterization of many materials in low-index orientations. To achieve the same level of characterization in more complex orientations requires that instrumental resolution be improved to values corresponding to the sub-Angstroem separations of atom positions projected into these orientations. Sub-Angstroem resolution in the high-resolution transmission electron microscope has been achieved in the last few years by software aberration correction, electron holography, and hardware aberration correction; the so-called 'one-Angstroem barrier' has been left behind. Aberration correction of the objective lens currently allows atomic-resolution imaging at the sub-0.8 A level and is advancing towards resolutions in the deep sub-Angstroem range (near 0.5 A). At current resolution levels, images with sub-Rayleigh resolution require calibration in order to pinpoint atom positions correctly. As resolution levels approach the 'sizes' of atoms, the atoms themselves will produce a limit to resolution, no matter how much the instrumental resolution is improved. By arranging imaging conditions suitably, each atom peak in the image can be narrower, so atoms are imaged smaller and may be resolved at finer separations.

  18. Self-correcting electronically scanned pressure sensor

    Science.gov (United States)

    Gross, C. (Inventor)

    1983-01-01

    A multiple channel high data rate pressure sensing device is disclosed for use in wind tunnels, spacecraft, airborne, process control, automotive, etc., pressure measurements. Data rates in excess of 100,000 measurements per second are offered with inaccuracies from temperature shifts less than 0.25% (nominal) of full scale over a temperature span of 55 C. The device consists of thirty-two solid state sensors, signal multiplexing electronics to electronically address each sensor, and digital electronic circuitry to automatically correct the inherent thermal shift errors of the pressure sensors and their associated electronics.

  19. Automated aberration correction of arbitrary laser modes in high numerical aperture systems.

    Science.gov (United States)

    Hering, Julian; Waller, Erik H; Von Freymann, Georg

    2016-12-12

    Controlling the point-spread-function in three-dimensional laser lithography is crucial for fabricating structures with highest definition and resolution. In contrast to microscopy, aberrations have to be physically corrected prior to writing, to create well defined doughnut modes, bottlebeams or multi foci modes. We report on a modified Gerchberg-Saxton algorithm for spatial-light-modulator based automated aberration compensation to optimize arbitrary laser-modes in a high numerical aperture system. Using circularly polarized light for the measurement and first-guess initial conditions for amplitude and phase of the pupil function our scalar approach outperforms recent algorithms with vectorial corrections. Besides laser lithography also applications like optical tweezers and microscopy might benefit from the method presented.

  20. Aberration correction in photoemission microscopy and applications in photonics and plasmonics

    Energy Technology Data Exchange (ETDEWEB)

    Koenenkamp, Rolf [Portland State Univ., Portland, OR (United States)

    2017-09-28

    We report on the design, assembly, operation and application of an aberration-corrected photoemission electron microscope. The instrument used novel hyperbolic mirror-correctors with two and three electrodes that allowed simultaneous correction of spherical and chromatic aberrations. A spatial resolution of 5.4nm was obtained with this instrument in 2009, and 4.7nm in subsequent years. New imaging methodology was introduced involving interferometric imaging of light diffraction. This methodology was applied in nano-photonics and in the characterization of surface-plasmon polaritons. Photonic crystals and waveguides, optical antennas and new plasmonic devices such as routers, localizers and filters were designed and demonstrated using the new capabilities offered by the microscope.

  1. Dynamic Correction of Higher-Order Deflection Aberrations in the Environmental SEM

    Czech Academy of Sciences Publication Activity Database

    Oral, Martin; Neděla, Vilém

    2015-01-01

    Roč. 21, S4 (2015), s. 194-199 ISSN 1431-9276 R&D Projects: GA ČR(CZ) GA14-22777S; GA MŠk(CZ) LO1212 Institutional support: RVO:68081731 Keywords : environmental SEM * ESEM * shifted deflection pivot point * Higher order deflection aberrations * vignetting * dynamic focusing * dynamic stigmator * dynamic correction Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.730, year: 2015

  2. Ultrashort echo-time MRI versus CT for skull aberration correction in MR-guided transcranial focused ultrasound: In vitro comparison on human calvaria.

    Science.gov (United States)

    Miller, G Wilson; Eames, Matthew; Snell, John; Aubry, Jean-François

    2015-05-01

    Transcranial magnetic resonance-guided focused ultrasound (TcMRgFUS) brain treatment systems compensate for skull-induced beam aberrations by adjusting the phase and amplitude of individual ultrasound transducer elements. These corrections are currently calculated based on a preacquired computed tomography (CT) scan of the patient's head. The purpose of the work presented here is to demonstrate the feasibility of using ultrashort echo-time magnetic resonance imaging (UTE MRI) instead of CT to calculate and apply aberration corrections on a clinical TcMRgFUS system. Phantom experiments were performed in three ex-vivo human skulls filled with tissue-mimicking hydrogel. Each skull phantom was imaged with both CT and UTE MRI. The MR images were then segmented into "skull" and "not-skull" pixels using a computationally efficient, threshold-based algorithm, and the resulting 3D binary skull map was converted into a series of 2D virtual CT images. Each skull was mounted in the head transducer of a clinical TcMRgFUS system (ExAblate Neuro, Insightec, Israel), and transcranial sonications were performed using a power setting of approximately 750 acoustic watts at several different target locations within the electronic steering range of the transducer. Each target location was sonicated three times: once using aberration corrections calculated from the actual CT scan, once using corrections calculated from the MRI-derived virtual CT scan, and once without applying any aberration correction. MR thermometry was performed in conjunction with each 10-s sonication, and the highest single-pixel temperature rise and surrounding-pixel mean were recorded for each sonication. The measured temperature rises were ∼ 45% larger for aberration-corrected sonications than for noncorrected sonications. This improvement was highly significant (p skull-induced ultrasound aberration corrections. Their results suggest that UTE MRI could be used instead of CT to implement such corrections on

  3. Time-resolved magnetic imaging in an aberration-corrected, energy-filtered photoemission electron microscope

    International Nuclear Information System (INIS)

    Nickel, F.; Gottlob, D.M.; Krug, I.P.; Doganay, H.; Cramm, S.; Kaiser, A.M.; Lin, G.; Makarov, D.; Schmidt, O.G.

    2013-01-01

    We report on the implementation and usage of a synchrotron-based time-resolving operation mode in an aberration-corrected, energy-filtered photoemission electron microscope. The setup consists of a new type of sample holder, which enables fast magnetization reversal of the sample by sub-ns pulses of up to 10 mT. Within the sample holder current pulses are generated by a fast avalanche photo diode and transformed into magnetic fields by means of a microstrip line. For more efficient use of the synchrotron time structure, we developed an electrostatic deflection gating mechanism capable of beam blanking within a few nanoseconds. This allows us to operate the setup in the hybrid bunch mode of the storage ring facility, selecting one or several bright singular light pulses which are temporally well-separated from the normal high-intensity multibunch pulse pattern. - Highlights: • A new time-resolving operation mode in photoemission electron microscopy is shown. • Our setup works within an energy-filtered, aberration-corrected PEEM. • A new gating system for bunch selection using synchrotron radiation is developed. • An alternative magnetic excitation system is developed. • First tr-imaging using an energy-filtered, aberration-corrected PEEM is shown

  4. Correction of 157-nm lens based on phase ring aberration extraction method

    Science.gov (United States)

    Meute, Jeff; Rich, Georgia K.; Conley, Will; Smith, Bruce W.; Zavyalova, Lena V.; Cashmore, Julian S.; Ashworth, Dominic; Webb, James E.; Rich, Lisa

    2004-05-01

    Early manufacture and use of 157nm high NA lenses has presented significant challenges including: intrinsic birefringence correction, control of optical surface contamination, and the use of relatively unproven materials, coatings, and metrology. Many of these issues were addressed during the manufacture and use of International SEMATECH"s 0.85NA lens. Most significantly, we were the first to employ 157nm phase measurement interferometry (PMI) and birefringence modeling software for lens optimization. These efforts yielded significant wavefront improvement and produced one of the best wavefront-corrected 157nm lenses to date. After applying the best practices to the manufacture of the lens, we still had to overcome the difficulties of integrating the lens into the tool platform at International SEMATECH instead of at the supplier facility. After lens integration, alignment, and field optimization were complete, conventional lithography and phase ring aberration extraction techniques were used to characterize system performance. These techniques suggested a wavefront error of approximately 0.05 waves RMS--much larger than the 0.03 waves RMS predicted by 157nm PMI. In-situ wavefront correction was planned for in the early stages of this project to mitigate risks introduced by the use of development materials and techniques and field integration of the lens. In this publication, we document the development and use of a phase ring aberration extraction method for characterizing imaging performance and a technique for correcting aberrations with the addition of an optical compensation plate. Imaging results before and after the lens correction are presented and differences between actual and predicted results are discussed.

  5. Investigation of focusing and correcting aberrations with binary amplitude and polarization modulation.

    Science.gov (United States)

    Fiala, Peter; Li, Yunqi; Dorrer, Christophe

    2018-02-01

    We investigate the focusing and correcting wavefront aberration of an optical wave using binary amplitude and polarization modulation. Focusing is performed by selectively modulating the field in different zones of the pupil to obtain on-axis constructive interference at a given distance. The conventional Soret zone plate (binary amplitude profile) is expanded to a polarization Soret zone plate with twice the focusing efficiency. Binary pixelated devices that approximate the sinusoidal transmission profile of a Gabor zone plate by spatial dithering are also investigated with amplitude and polarization modulation. Wavefront aberrations are corrected by modulation of the field in the pupil plane to prevent destructive interference in the focal plane of an ideal focusing element. Polarization modulation improves the efficiency obtained by amplitude-only modulation, with a gain that depends on the aberration. Experimental results obtained with Cr-on-glass devices for amplitude modulation and liquid crystal devices operating in the Mauguin condition for polarization modulation are in very good agreement with simulations.

  6. A monochromatic, aberration-corrected, dual-beam low energy electron microscope.

    Science.gov (United States)

    Mankos, Marian; Shadman, Khashayar

    2013-07-01

    The monochromatic, aberration-corrected, dual-beam low energy electron microscope (MAD-LEEM) is a novel instrument aimed at imaging of nanostructures and surfaces at sub-nanometer resolution that includes a monochromator, aberration corrector and dual beam illumination. The monochromator reduces the energy spread of the illuminating electron beam, which significantly improves spectroscopic and spatial resolution. The aberration corrector utilizes an electron mirror with negative aberrations that can be used to compensate the aberrations of the LEEM objective lens for a range of electron energies. Dual flood illumination eliminates charging generated when a conventional LEEM is used to image insulating specimens. MAD-LEEM is designed for the purpose of imaging biological and insulating specimens, which are difficult to image with conventional LEEM, Low-Voltage SEM, and TEM instruments. The MAD-LEEM instrument can also be used as a general purpose LEEM with significantly improved resolution. The low impact energy of the electrons is critical for avoiding beam damage, as high energy electrons with keV kinetic energies used in SEMs and TEMs cause irreversible change to many specimens, in particular biological materials. A potential application for MAD-LEEM is in DNA sequencing, which demands imaging techniques that enable DNA sequencing at high resolution and speed, and at low cost. The key advantages of the MAD-LEEM approach for this application are the low electron impact energies, the long read lengths, and the absence of heavy-atom DNA labeling. Image contrast simulations of the detectability of individual nucleotides in a DNA strand have been developed in order to refine the optics blur and DNA base contrast requirements for this application. Copyright © 2013 Elsevier B.V. All rights reserved.

  7. Progress toward an aberration-corrected low energy electron microscope for DNA sequencing and surface analysis.

    Science.gov (United States)

    Mankos, Marian; Shadman, Khashayar; N'diaye, Alpha T; Schmid, Andreas K; Persson, Henrik H J; Davis, Ronald W

    2012-11-01

    Monochromatic, aberration-corrected, dual-beam low energy electron microscopy (MAD-LEEM) is a novel imaging technique aimed at high resolution imaging of macromolecules, nanoparticles, and surfaces. MAD-LEEM combines three innovative electron-optical concepts in a single tool: a monochromator, a mirror aberration corrector, and dual electron beam illumination. The monochromator reduces the energy spread of the illuminating electron beam, which significantly improves spectroscopic and spatial resolution. The aberration corrector is needed to achieve subnanometer resolution at landing energies of a few hundred electronvolts. The dual flood illumination approach eliminates charging effects generated when a conventional, single-beam LEEM is used to image insulating specimens. The low landing energy of electrons in the range of 0 to a few hundred electronvolts is also critical for avoiding radiation damage, as high energy electrons with kilo-electron-volt kinetic energies cause irreversible damage to many specimens, in particular biological molecules. The performance of the key electron-optical components of MAD-LEEM, the aberration corrector combined with the objective lens and a magnetic beam separator, was simulated. Initial results indicate that an electrostatic electron mirror has negative spherical and chromatic aberration coefficients that can be tuned over a large parameter range. The negative aberrations generated by the electron mirror can be used to compensate the aberrations of the LEEM objective lens for a range of electron energies and provide a path to achieving subnanometer spatial resolution. First experimental results on characterizing DNA molecules immobilized on Au substrates in a LEEM are presented. Images obtained in a spin-polarized LEEM demonstrate that high contrast is achievable at low electron energies in the range of 1-10 eV and show that small changes in landing energy have a strong impact on the achievable contrast. The MAD-LEEM approach

  8. Numerical correction of anti-symmetric aberrations in single HRTEM images of weakly scattering 2D-objects

    International Nuclear Information System (INIS)

    Lehtinen, Ossi; Geiger, Dorin; Lee, Zhongbo; Whitwick, Michael Brian; Chen, Ming-Wei; Kis, Andras; Kaiser, Ute

    2015-01-01

    Here, we present a numerical post-processing method for removing the effect of anti-symmetric residual aberrations in high-resolution transmission electron microscopy (HRTEM) images of weakly scattering 2D-objects. The method is based on applying the same aberrations with the opposite phase to the Fourier transform of the recorded image intensity and subsequently inverting the Fourier transform. We present the theoretical justification of the method, and its verification based on simulated images in the case of low-order anti-symmetric aberrations. Ultimately the method is applied to experimental hardware aberration-corrected HRTEM images of single-layer graphene and MoSe 2 resulting in images with strongly reduced residual low-order aberrations, and consequently improved interpretability. Alternatively, this method can be used to estimate by trial and error the residual anti-symmetric aberrations in HRTEM images of weakly scattering objects

  9. The influence of Cs/Cc correction in analytical imaging and spectroscopy in scanning and transmission electron microscopy

    International Nuclear Information System (INIS)

    Zaluzec, Nestor J.

    2015-01-01

    Aberration correction in scanning/transmission electron microscopy (S/TEM) owes much to the efforts of a small dedicated group of innovators. Leading that frontier has been Prof. Harald Rose. To date his leadership and dynamic personality has spearheaded our ability to leave behind many of the limitations imposed by spherical aberration (C s ) in high resolution phase contrast imaging. Following shortly behind, has been the development of chromatic aberration correction (C c ) which augments those accomplishments. In this paper we will review and summarize how the combination of C s /C c technology enhances our ability to conduct hyperspectral imaging and spectroscopy in today's and future computationally mediated experiments in both thin as well as realistic specimens in vacuo and during in-situ/environmental experiments

  10. Index mismatch aberration correction over long working distances using spatial light modulation.

    Science.gov (United States)

    Gjonaj, Bergin; Johnson, Patrick; Bonn, Mischa; Domke, Katrin F

    2012-11-20

    For many microscopy applications, millimeters-long free working distances (LWD) are required. However, the high resolution and contrast of LWD objectives operated in air are lost when introducing glass and/or liquid with the sample. We propose to use spatial light modulation to correct for such beam aberrations caused by refractive index mismatches. Focusing a monochromatic laser beam with a 10 mm working distance air objective (50×, 0.5 NA) through air, glass, and water, we manage to restore a sharp, intense focus (FWHMLWD air objectives, extending their usage beyond applications in air.

  11. Geometrical E-beam proximity correction for raster scan systems

    Science.gov (United States)

    Belic, Nikola; Eisenmann, Hans; Hartmann, Hans; Waas, Thomas

    1999-04-01

    High pattern fidelity is a basic requirement for the generation of masks containing sub micro structures and for direct writing. Increasing needs mainly emerging from OPC at mask level and x-ray lithography require a correction of the e-beam proximity effect. The most part of e-beam writers are raster scan system. This paper describes a new method for geometrical pattern correction in order to provide a correction solution for e-beam system that are not able to apply variable doses.

  12. Reduction of chromatic aberration influences in vertical scanning white-light interferometry

    International Nuclear Information System (INIS)

    Lehmann, Peter; Kühnhold, Peter; Xie, Weichang

    2014-01-01

    Vertical scanning white-light interferometry (SWLI) is a well-established method that is widely used in high precision surface topography measurement. However, SWLI results show characteristic slope-dependent errors due to dispersion effects and lateral chromatic aberrations of the optical imaging system. In this paper, we present methods to characterize these systematic errors related to dispersion and lateral colour. Lateral colour leads to field-dependent systematic discrepancies of the topography data obtained from the envelope position of a low-coherence interference signal and the data resulting from its interference phase. Hence, an erroneous fringe order obtained from the envelope position leads to a 2π phase jump and thus to a so-called ghost step in the measured topography. Our first approach to solve this problem is based on the measurement of a surface standard of well-known geometry. By comparison of measurement results related to the envelope position and the phase of SWLI signals, the systematic error is estimated and a numerical error compensation method is proposed. Both experimental and simulation results confirm the validity of this numerical method. In addition, using an improved design of a white-light Michelson interferometer we demonstrate experimentally that lateral chromatic aberrations and dispersion influences can be reduced also in a physical way. In this context, a conventional long working distance microscope objective is used which was not originally designed for a Michelson interference microscope. (paper)

  13. Automatic low-order aberration correction based on geometrical optics for slab lasers.

    Science.gov (United States)

    Yu, Xin; Dong, Lizhi; Lai, Boheng; Yang, Ping; Liu, Yong; Kong, Qingfeng; Yang, Kangjian; Tang, Guomao; Xu, Bing

    2017-02-20

    In this paper, we present a method based on geometry optics to simultaneously correct low-order aberrations and reshape the beams of slab lasers. A coaxial optical system with three lenses is adapted. The positions of the three lenses are directly calculated based on the beam parameters detected by wavefront sensors. The initial sizes of the input beams are 1.8  mm×11  mm, and peak-to-valley (PV) values of the wavefront range up to several tens of microns. After automatic correction, the dimensions may reach nearly 22  mm×22  mm as expected, and PV values of the wavefront are less than 2 μm. The effectiveness and precision of this method are verified with experiments.

  14. Coherence and diffraction limited resolution in microscopic OCT by a unified approach for the correction of dispersion and aberrations

    Science.gov (United States)

    Schulz-Hildebrandt, H.; Münter, Michael; Ahrens, M.; Spahr, H.; Hillmann, D.; König, P.; Hüttmann, G.

    2018-03-01

    Optical coherence tomography (OCT) images scattering tissues with 5 to 15 μm resolution. This is usually not sufficient for a distinction of cellular and subcellular structures. Increasing axial and lateral resolution and compensation of artifacts caused by dispersion and aberrations is required to achieve cellular and subcellular resolution. This includes defocus which limit the usable depth of field at high lateral resolution. OCT gives access the phase of the scattered light and hence correction of dispersion and aberrations is possible by numerical algorithms. Here we present a unified dispersion/aberration correction which is based on a polynomial parameterization of the phase error and an optimization of the image quality using Shannon's entropy. For validation, a supercontinuum light sources and a costume-made spectrometer with 400 nm bandwidth were combined with a high NA microscope objective in a setup for tissue and small animal imaging. Using this setup and computation corrections, volumetric imaging at 1.5 μm resolution is possible. Cellular and near cellular resolution is demonstrated in porcine cornea and the drosophila larva, when computational correction of dispersion and aberrations is used. Due to the excellent correction of the used microscope objective, defocus was the main contribution to the aberrations. In addition, higher aberrations caused by the sample itself were successfully corrected. Dispersion and aberrations are closely related artifacts in microscopic OCT imaging. Hence they can be corrected in the same way by optimization of the image quality. This way microscopic resolution is easily achieved in OCT imaging of static biological tissues.

  15. Optimum aberration coefficients for recording high-resolution off-axis holograms in a Cs-corrected TEM

    Energy Technology Data Exchange (ETDEWEB)

    Linck, Martin, E-mail: linck@ceos-gmbh.de [CEOS GmbH, Englerstr. 28, D-69126 Heidelberg (Germany)

    2013-01-15

    Amongst the impressive improvements in high-resolution electron microscopy, the Cs-corrector also has significantly enhanced the capabilities of off-axis electron holography. Recently, it has been shown that the signal above noise in the reconstructable phase can be significantly improved by combining holography and hardware aberration correction. Additionally, with a spherical aberration close to zero, the traditional optimum focus for recording high-resolution holograms ('Lichte's defocus') has become less stringent and both, defocus and spherical aberration, can be selected freely within a certain range. This new degree of freedom can be used to improve the signal resolution in the holographically reconstructed object wave locally, e.g. at the atomic positions. A brute force simulation study for an aberration corrected 200 kV TEM is performed to determine optimum values for defocus and spherical aberration for best possible signal to noise in the reconstructed atomic phase signals. Compared to the optimum aberrations for conventional phase contrast imaging (NCSI), which produce 'bright atoms' in the image intensity, the resulting optimum values of defocus and spherical aberration for off-axis holography enable 'black atom contrast' in the hologram. However, they can significantly enhance the local signal resolution at the atomic positions. At the same time, the benefits of hardware aberration correction for high-resolution off-axis holography are preserved. It turns out that the optimum is depending on the object and its thickness and therefore not universal. -- Highlights: Black-Right-Pointing-Pointer Optimized aberration parameters for high-resolution off-axis holography. Black-Right-Pointing-Pointer Simulation and analysis of noise in high-resolution off-axis holograms. Black-Right-Pointing-Pointer Improving signal resolution in the holographically reconstructed phase shift. Black-Right-Pointing-Pointer Comparison of &apos

  16. Optimum aberration coefficients for recording high-resolution off-axis holograms in a Cs-corrected TEM

    International Nuclear Information System (INIS)

    Linck, Martin

    2013-01-01

    Amongst the impressive improvements in high-resolution electron microscopy, the Cs-corrector also has significantly enhanced the capabilities of off-axis electron holography. Recently, it has been shown that the signal above noise in the reconstructable phase can be significantly improved by combining holography and hardware aberration correction. Additionally, with a spherical aberration close to zero, the traditional optimum focus for recording high-resolution holograms (“Lichte's defocus”) has become less stringent and both, defocus and spherical aberration, can be selected freely within a certain range. This new degree of freedom can be used to improve the signal resolution in the holographically reconstructed object wave locally, e.g. at the atomic positions. A brute force simulation study for an aberration corrected 200 kV TEM is performed to determine optimum values for defocus and spherical aberration for best possible signal to noise in the reconstructed atomic phase signals. Compared to the optimum aberrations for conventional phase contrast imaging (NCSI), which produce “bright atoms” in the image intensity, the resulting optimum values of defocus and spherical aberration for off-axis holography enable “black atom contrast” in the hologram. However, they can significantly enhance the local signal resolution at the atomic positions. At the same time, the benefits of hardware aberration correction for high-resolution off-axis holography are preserved. It turns out that the optimum is depending on the object and its thickness and therefore not universal. -- Highlights: ► Optimized aberration parameters for high-resolution off-axis holography. ► Simulation and analysis of noise in high-resolution off-axis holograms. ► Improving signal resolution in the holographically reconstructed phase shift. ► Comparison of “black” and “white” atom contrast in off-axis holograms.

  17. Prospects for versatile phase manipulation in the TEM: Beyond aberration correction

    International Nuclear Information System (INIS)

    Guzzinati, Giulio; Clark, Laura; Béché, Armand; Juchtmans, Roeland; Van Boxem, Ruben; Mazilu, Michael; Verbeeck, Jo

    2015-01-01

    In this paper we explore the desirability of a transmission electron microscope in which the phase of the electron wave can be freely controlled. We discuss different existing methods to manipulate the phase of the electron wave and their limitations. We show how with the help of current techniques the electron wave can already be crafted into specific classes of waves each having their own peculiar properties. Assuming a versatile phase modulation device is feasible, we explore possible benefits and methods that could come into existence borrowing from light optics where the so-called spatial light modulators provide programmable phase plates for quite some time now. We demonstrate that a fully controllable phase plate building on Harald Rose's legacy in aberration correction and electron optics in general would open an exciting field of research and applications. - Highlights: • We offer a review of available phase manipulation techniques. • We demonstrate a method for producing Airy waves through aberration manipulation. • We outline hypothetical applications of arbitrary phase manipulation methods

  18. Quantification by aberration corrected (S)TEM of boundaries formed by symmetry breaking phase transformations

    Energy Technology Data Exchange (ETDEWEB)

    Schryvers, D., E-mail: nick.schryvers@uantwerpen.be [EMAT, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium); Salje, E.K.H. [Department of Earth Sciences, University of Cambridge, Cambridge CB2 3EQ (United Kingdom); Nishida, M. [Department of Engineering Sciences for Electronics and Materials, Faculty of Engineering Sciences, Kyushu University, Kasuga, Fukuoka 816-8580 (Japan); De Backer, A. [EMAT, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium); Idrissi, H. [EMAT, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium); Institute of Mechanics, Materials and Civil Engineering, Université Catholique de Louvain, Place Sainte Barbe, 2, B-1348, Louvain-la-Neuve (Belgium); Van Aert, S. [EMAT, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium)

    2017-05-15

    The present contribution gives a review of recent quantification work of atom displacements, atom site occupations and level of crystallinity in various systems and based on aberration corrected HR(S)TEM images. Depending on the case studied, picometer range precisions for individual distances can be obtained, boundary widths at the unit cell level determined or statistical evolutions of fractions of the ordered areas calculated. In all of these cases, these quantitative measures imply new routes for the applications of the respective materials. - Highlights: • Quantification of picometer displacements at ferroelastic twin boundary in CaTiO{sub 3.} • Quantification of kinks in meandering ferroelectric domain wall in LiNbO{sub 3}. • Quantification of column occupation in anti-phase boundary in Co-Pt. • Quantification of atom displacements at twin boundary in Ni-Ti B19′ martensite.

  19. Optimization and stability of the contrast transfer function in aberration-corrected electron microscopy

    International Nuclear Information System (INIS)

    Tromp, R.M.; Schramm, S.M.

    2013-01-01

    The Contrast Transfer Function (CTF) describes the manner in which the electron microscope modifies the object exit wave function as a result of objective lens aberrations. For optimum resolution in C 3 -corrected microscopes it is well established that a small negative value of C 3 , offset by positive values of C 5 and defocus C 1 results in the most optimal instrument resolution, and optimization of the CTF has been the subject of several studies. Here we describe a simple design procedure for the CTF that results in a most even transfer of information below the resolution limit. We address not only the resolution of the instrument, but also the stability of the CTF in the presence of small disturbances in C 1 and C 3 . We show that resolution can be traded for stability in a rational and transparent fashion. These topics are discussed quantitatively for both weak-phase and strong-phase (or amplitude) objects. The results apply equally to instruments at high electron energy (TEM) and at very low electron energy (LEEM), as the basic optical properties of the imaging lenses are essentially identical. - Highlights: ► An optimized Contrast Transfer Function for aberration corrected electron microscopes is proposed. ► Based on the properties of the CTF near optimum settings, we address its stability. ► Over some range of parameters resolution can be traded for stability. ► These issues are addressed for weak-phase objects, as well as strong-phase and amplitude object. ► We compare our results with CTF settings previously proposed

  20. TOPICAL REVIEW: Present status and future prospects of spherical aberration corrected TEM/STEM for study of nanomaterials

    Directory of Open Access Journals (Sweden)

    Nobuo Tanaka

    2008-01-01

    Full Text Available The present status of Cs-corrected TEM/STEM is described from the viewpoint of the observation of nanomaterials. Characteristic features in TEM and STEM are explained using the experimental data obtained by our group and other research groups. Cs correction up to the 3rd-order aberration of an objective lens has already been established and research interest is focused on correcting the 5th-order spherical aberration and the chromatic aberration in combination with the development of a monochromator below an electron gun for smaller point-to-point resolution in optics. Another fundamental area of interest is the limitation of TEM and STEM resolution from the viewpoint of the scattering of electrons in crystals. The minimum size of the exit-wave function below samples undergoing TEM imaging is determined from the calculation of scattering around related atomic columns in the crystals. STEM does not have this limitation because the resolution is, in principle, determined by the probe size. One of the future prospects of Cs-corrected TEM/STEM is the possibility of extending the space around the sample holder by correcting the chromatic and spherical aberrations. This wider space will contribute to the ease of performing in situ experiments and various combinations of TEM and other analysis methods. High-resolution, in situ dynamic and 3D observations/analysis are the most important keywords in the next decade of high-resolution electron microscopy.

  1. Use of Gamma Correction Pinhole Bone Scans in Trauma

    International Nuclear Information System (INIS)

    Bahk, Youg Whee; Chung, Youg An; Park, Jung Mee

    2012-01-01

    99 mTc hydroxydiphosphonate (HDP) bone scanning is a classic metabolic nuclear imaging method and the most frequently performed examination. Clinically, it has long been cherished as an indispensable diagnostic screening tool and for monitoring of patients with bone, joint, and soft tissue diseases. The HDP bone scan, the pinhole scan in particular, is known for its ability to detect increased, decreased, or defective tracer uptake along with magnified anatomy. Unfortunately, however, the findings of such uptake changes are not specific in many traumatic bone disorders, especially when lesions are minute and complex. This study discusses the recently introduced gamma correction pinhole bone scan (GCPBS), emphasizing its usefulness in the diagnosis of traumatic bone diseases including occult fractures; and fish vertebra. Indeed, GCPBS can remarkably enhance the diagnostic feasibility of HDP pinhole bone scans by refining the topography, pathologic anatomy, and altered chemical profile of the traumatic diseases in question. The fine and precise depiction of anatomic and metabolic changes in these diseases has been shown to be unique to GCPBS, and they are not appreciated on conventional radiographs, multiple detector CT, or ultrasonographs. It is true that MR imaging can portray proton change, but understandably, it is a manifestation that is common to any bone disease

  2. First experimental proof for aberration correction in XPEEM: Resolution, transmission enhancement, and limitation by space charge effects

    International Nuclear Information System (INIS)

    Schmidt, Th.; Sala, A.; Marchetto, H.; Umbach, E.; Freund, H.-J.

    2013-01-01

    The positive effect of double aberration correction in x-ray induced Photoelectron Emission Microscopy (XPEEM) has been successfully demonstrated for both, the lateral resolution and the transmission, using the Au 4f XPS peak for element specific imaging at a kinetic energy of 113 eV. The lateral resolution is improved by a factor of four, compared to a non-corrected system, whereas the transmission is enhanced by a factor of 5 at a moderate resolution of 80 nm. With an optimized system setting, a lateral resolution of 18 nm could be achieved, which is up to now the best value reported for energy filtered XPEEM imaging. However, the absolute resolution does not yet reach the theoretical limit of 2 nm, which is due to space charge limitation. This occurs along the entire optical axis up to the contrast aperture. In XPEEM the pulsed time structure of the exciting soft x-ray light source causes a short and highly intense electron pulse, which results in an image blurring. In contrast, the imaging with elastically reflected electrons in the low energy electron microscopy (LEEM) mode yields a resolution clearly below 5 nm. Technical solutions to reduce the space charge effect in an aberration-corrected spectro-microscope are discussed. - Highlights: ► First successful double aberration correction in XPEEM. ► Improvement of resolution and transmission by aberration correction. ► Lateral resolution of 18 nm in energy filtered XPEEM is the best up to now reported value. ► First investigation of space charge effects in aberrations corrected PEEM

  3. Simultaneous correction of large low-order and high-order aberrations with a new deformable mirror technology

    Science.gov (United States)

    Rooms, F.; Camet, S.; Curis, J. F.

    2010-02-01

    A new technology of deformable mirror will be presented. Based on magnetic actuators, these deformable mirrors feature record strokes (more than +/- 45μm of astigmatism and focus correction) with an optimized temporal behavior. Furthermore, the development has been made in order to have a large density of actuators within a small clear aperture (typically 52 actuators within a diameter of 9.0mm). We will present the key benefits of this technology for vision science: simultaneous correction of low and high order aberrations, AO-SLO image without artifacts due to the membrane vibration, optimized control, etc. Using recent papers published by Doble, Thibos and Miller, we show the performances that can be achieved by various configurations using statistical approach. The typical distribution of wavefront aberrations (both the low order aberration (LOA) and high order aberration (HOA)) have been computed and the correction applied by the mirror. We compare two configurations of deformable mirrors (52 and 97 actuators) and highlight the influence of the number of actuators on the fitting error, the photon noise error and the effective bandwidth of correction.

  4. Low-energy foil aberration corrector

    International Nuclear Information System (INIS)

    Aken, R.H. van; Hagen, C.W.; Barth, J.E.; Kruit, P.

    2002-01-01

    A spherical and chromatic aberration corrector for electron microscopes is proposed, consisting of a thin foil sandwiched between two apertures. The electrons are retarded at the foil to almost zero energy, so that they can travel ballistically through the foil. It is shown that such a low-voltage corrector has a negative spherical aberration for not too large distances between aperture and foil, as well as a negative chromatic aberration. For various distances the third- and fifth-order spherical aberration coefficients and the first- and second-order chromatic aberration coefficients are calculated using ray tracing. Provided that the foils have sufficient electron transmission the corrector is able to correct the third-order spherical aberration and the first-order chromatic aberration of a typical low-voltage scanning electron microscope. Preliminary results show that the fifth-order spherical aberration and the second-order chromatic aberration can be kept sufficiently low

  5. Double aberration-corrected TEM/STEM of tungstated zirconia nanocatalysts for the synthesis of paracetamol

    International Nuclear Information System (INIS)

    Yoshida, K; Boyes, E D; Gai, P L; Shiju, N R; Brown, D R

    2010-01-01

    We report highly active tungstated zirconia nanocatalysts for the synthesis of paracetamol by Beckmann rearrangement of 4-hydroxyacetophenone oxime. Double aberration-corrected (2AC)-TEM/STEM studies were performed in a JEOL 2200FS FEG TEM/STEM at the 1 Angstrom (1 A = 0.1 nanometer) level. Observations at close to zero defocus were carried out using the AC-TEM as well as AC-STEM including high angle annular dark field (HAADF) imaging, from the same areas of the catalyst crystallites. The studies from the same areas have revealed the location and the nanostructure of the polytungstate species (clusters) and the nanograins of zirconia. The AC (S)TEM was crucial to observe the nanostructure and location of polytungstate clusters on the zirconia grains. Polytungstate clusters as small as 0.5 nm have been identified using the HAADF-STEM. The nanostructures of the catalyst and the W surface density have been correlated with paracetamol reaction studies. The results demonstrate the nature of active sites and high activity of the tungstated zirconia nanocatalyst, which is an environmentally clean alternative to the current homogeneous process.

  6. Double aberration-corrected TEM/STEM of tungstated zirconia nanocatalysts for the synthesis of paracetamol

    Energy Technology Data Exchange (ETDEWEB)

    Yoshida, K; Boyes, E D; Gai, P L [York JEOL Nanocentre (United Kingdom); Shiju, N R; Brown, D R, E-mail: pgb500@york.ac.u [Department of Chemical and Biological Sciences, University of Huddersfield, Huddersfield, HD1 3DH (United Kingdom)

    2010-07-01

    We report highly active tungstated zirconia nanocatalysts for the synthesis of paracetamol by Beckmann rearrangement of 4-hydroxyacetophenone oxime. Double aberration-corrected (2AC)-TEM/STEM studies were performed in a JEOL 2200FS FEG TEM/STEM at the 1 Angstrom (1 A = 0.1 nanometer) level. Observations at close to zero defocus were carried out using the AC-TEM as well as AC-STEM including high angle annular dark field (HAADF) imaging, from the same areas of the catalyst crystallites. The studies from the same areas have revealed the location and the nanostructure of the polytungstate species (clusters) and the nanograins of zirconia. The AC (S)TEM was crucial to observe the nanostructure and location of polytungstate clusters on the zirconia grains. Polytungstate clusters as small as 0.5 nm have been identified using the HAADF-STEM. The nanostructures of the catalyst and the W surface density have been correlated with paracetamol reaction studies. The results demonstrate the nature of active sites and high activity of the tungstated zirconia nanocatalyst, which is an environmentally clean alternative to the current homogeneous process.

  7. Is attenuation correction of myocardial SPECT scans worth the effort?

    International Nuclear Information System (INIS)

    Bui, C.; Nguyen, D.; Dixson, H.; Saunders, C.; Cook, P.; Burnett, P.; Croll, F.; Dunn, R.; Hasche, E.; Kelleher, P.; Nasser, F.; Wilson, D.; Lee, K.

    2000-01-01

    Full text: Gated (GS), attenuation-corrected (AC) and non-attenuation-corrected (NAC) myocardial SPECT scans were performed after injection of 99 Tc m -Sestamibi (MIBI) at peak stress in 253 patients between September 1998 and March 1999. 60 patients have undergone cardiac catheterisation (37 males, 23 females, age range 34-80). For whole heart analysis, significant coronary disease was defined as 50% or greater diameter narrowing in any of the coronary arteries and/or documented myocardial infarction. For vascular territory analysis, significant coronary disease was defined as 50% or greater diameter narrowing of any artery in that territory. The three coronary artery territories were assigned as: left anterior descending (LAD), left circumflex (LCA) and right coronary (RCA). The septum, apex and anterior wall; the lateral wall; and the inferior wall were assigned to the LAD; LCA; and RCA territories respectively. In conclusion for this selected subgroup of patients with angiographic follow-up, NAC, AC and GS were of similar accuracy in the detection of significant CAD in both whole heart analysis and individual vascular territory analysis. AC and GS were of superior specificity when compared with NAC in both whole heart analysis and individual vascular territory analysis. AC and GS may be of additional diagnostic value in improving the specificity of NAC. Further outcome data will be presented. Copyright (2000) The Australian and New Zealand Society of Nuclear Medicine Inc

  8. Is attenuation correction of myocardial SPET scans worth the effort?

    International Nuclear Information System (INIS)

    Nguyen, D.; Saunders, C.; Dixson, H.; Cook, P.; Burnett, P.; Croll, F.; Dunn, R.; Hasche, E.; Kelleher, P.; Nasser, F.; Wilson, D.; Lee, K.

    1999-01-01

    Full text: In this prospective study, we compared gated (GS), attenuation-corrected (AC) and non-attenuation-corrected (NAC) myocardial SPET scans. 119 consecutive patients were scanned after 800 MBq 99 Tc m -Sestamibi (MIBI) injected at peak stress. AC studies were performed using a Siemens Multispect 3 triple-headed camera with a MμSIC attenuation correction system. Transmission data were provided by an Am241 line source mounted opposite an offset fan beam collimator. Simultaneous emission data were collected from all 3 heads over a 360deg rotation (acquisition time 25 min). The NAC and GS studies were performed using a Siemens ECAM variable-angle dual-headed gamma camera using 8 gating frames over a 90deg rotation (acquisition time 15 min). The myocardium was divided into 9 segments and the studies were reported separately by two observers. Clinical data and angiography results were obtained when available. For GS, myocardial segments with normal systolic wall thickening were considered to have normal perfusion. AC studies were used as the standard for measuring myocardial perfusion. In the 119 patients studied, the overall sensitivity, specificity and accuracy for NAC vs AC were 100%, 25%, 54% and for GS vs AC were 86%, 84% and 85% respectively. There were 265 abnormal segments on NAC. GS demonstrated normal thickening in 90/265 segments and AC demonstrated normal perfusion in 94/265 segments. There were 33 segments with discordant GS and AC. 16/33 segments (9 inferior, 3 anterior, 4 other) with normal thickening had abnormal perfusion on AC and 17/33 segments (9 inferior, 6 anterior, 2 other) with abnormal thickening had normal perfusion on AC. Weight and sex did not predict discordance. In conclusion, attenuation artefacts are common and are not predicted by body habitus or sex. They are usually accurately identified by normal systolic wall thickening on GS. GS is strongly recommended when AC is not available. AC provides additional information, particularly

  9. Exploring the atomic structure of 1.8 nm monolayer-protected gold clusters with aberration-corrected STEM

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jian; Jian, Nan; Ornelas, Isabel; Pattison, Alexander J. [Nanoscale Physics Research Laboratory, School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT (United Kingdom); Lahtinen, Tanja; Salorinne, Kirsi [Department of Chemistry, Nanoscience Center, University of Jyväskylä, FI-40014 Jyväskylä (Finland); Häkkinen, Hannu [Department of Chemistry, Nanoscience Center, University of Jyväskylä, FI-40014 Jyväskylä (Finland); Department of Physics, Nanoscience Center, University of Jyväskylä, FI-40014 Jyväskylä (Finland); Palmer, Richard E., E-mail: richardepalmerwork@yahoo.com [Nanoscale Physics Research Laboratory, School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT (United Kingdom)

    2017-05-15

    Monolayer-protected (MP) Au clusters present attractive quantum systems with a range of potential applications e.g. in catalysis. Knowledge of the atomic structure is needed to obtain a full understanding of their intriguing physical and chemical properties. Here we employed aberration-corrected scanning transmission electron microscopy (ac-STEM), combined with multislice simulations, to make a round-robin investigation of the atomic structure of chemically synthesised clusters with nominal composition Au{sub 144}(SCH{sub 2}CH{sub 2}Ph){sub 60} provided by two different research groups. The MP Au clusters were “weighed” by the atom counting method, based on their integrated intensities in the high angle annular dark field (HAADF) regime and calibrated exponent of the Z dependence. For atomic structure analysis, we compared experimental images of hundreds of clusters, with atomic resolution, against a variety of structural models. Across the size range 123–151 atoms, only 3% of clusters matched the theoretically predicted Au{sub 144}(SR){sub 60} structure, while a large proportion of the clusters were amorphous (i.e. did not match any model structure). However, a distinct ring-dot feature, characteristic of local icosahedral symmetry, was observed in about 20% of the clusters. - Highlights: • Chemically synthesised gold clusters were “weighed” by atom counting to get true size. • Image simulations show a few percent of clusters have the predicted atomic structure. • But a specific ring-dot feature indicates local icosahedral order in many clusters.

  10. Aberration corrected and monochromated environmental transmission electron microscopy: challenges and prospects for materials science

    DEFF Research Database (Denmark)

    Hansen, Thomas Willum; Wagner, Jakob Birkedal; Dunin-Borkowski, Rafal E.

    2010-01-01

    The latest generation of environmental transmission electron microscopes incorporates aberration correctors and monochromators, allowing studies of chemical reactions and growth processes with improved spatial resolution and spectral sensitivity. Here, we describe the performance of such an instr...

  11. The influence of C{sub s}/C{sub c} correction in analytical imaging and spectroscopy in scanning and transmission electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Zaluzec, Nestor J., E-mail: zaluzec@microscopy.com

    2015-04-15

    Aberration correction in scanning/transmission electron microscopy (S/TEM) owes much to the efforts of a small dedicated group of innovators. Leading that frontier has been Prof. Harald Rose. To date his leadership and dynamic personality has spearheaded our ability to leave behind many of the limitations imposed by spherical aberration (C{sub s}) in high resolution phase contrast imaging. Following shortly behind, has been the development of chromatic aberration correction (C{sub c}) which augments those accomplishments. In this paper we will review and summarize how the combination of C{sub s}/C{sub c} technology enhances our ability to conduct hyperspectral imaging and spectroscopy in today's and future computationally mediated experiments in both thin as well as realistic specimens in vacuo and during in-situ/environmental experiments.

  12. Higher-order aberrations and best-corrected visual acuity in Native American children with a high prevalence of astigmatism.

    Science.gov (United States)

    Miller, Joseph M; Harvey, Erin M; Schwiegerling, Jim

    2015-08-01

    To determine whether higher-order aberrations (HOAs) in children from a highly astigmatic population differ from population norms and whether HOAs are associated with astigmatism and reduced best-corrected visual acuity. Subjects were 218 Tohono O'odham Native American children 5-9 years of age. Noncycloplegic HOA measurements were obtained with a handheld Shack-Hartmann sensor (SHS). Signed (z06s to z14s) and unsigned (z06u to z14u) wavefront aberration Zernike coefficients Z(3,-3) to Z(4,4) were rescaled for a 4 mm diameter pupil and compared to adult population norms. Cycloplegic refraction and best-corrected logMAR letter visual acuity (BCVA) were also measured. Regression analyses assessed the contribution of astigmatism (J0) and HOAs to BCVA. The mean root-mean-square (RMS) HOA of 0.191 ± 0.072 μm was significantly greater than population norms (0.100 ± 0.044 μm). All unsigned HOA coefficients (z06u to z14u) and all signed coefficients except z09s, z10s, and z11s were significantly larger than population norms. Decreased BCVA was associated with astigmatism (J0) and spherical aberration (z12u) but not RMS coma, with the effect of J0 about 4 times as great as z12u. Tohono O'odham children show elevated HOAs compared to population norms. Astigmatism and unsigned spherical aberration are associated with decreased acuity, but the effects of spherical aberration are minimal and not clinically significant. Copyright © 2015 American Association for Pediatric Ophthalmology and Strabismus. Published by Elsevier Inc. All rights reserved.

  13. Changes in higher order aberrations after wavefront-guided PRK for correction of low to moderate myopia and myopic astigmatism: two-year follow-up.

    Science.gov (United States)

    Wigledowska-Promienska, D; Zawojska, I

    2007-01-01

    To assess efficacy, safety, and changes in higher order aberrations after wavefront-guided photorefractive keratectomy (PRK) in comparison with conventional PRK for low to moderate myopia with myopic astigmatism using a WASCA Workstation with the MEL 70 G-Scan excimer laser. A total of 126 myopic or myopic-astigmatic eyes of 112 patients were included in this retrospective study. Patients were divided into two groups: Group 1, the study group; and Group 2, the control group. Group 1 consisted of 78 eyes treated with wavefront-guided PRK. Group 2 consisted of 48 eyes treated with spherocylindrical conventional PRK. Two years postoperatively, in Group 1, 5% of eyes achieved an uncorrected visual acuity (UCVA) of 0.05; 69% achieved a UCVA of 0.00; 18% of eyes experienced enhanced visual acuity of -0.18 and 8% of -0.30. In Group 2, 8% of eyes achieved a UCVA of 0.1; 25% achieved a UCVA of 0.05; and 67% achieved a UCVA of 0.00 according to logMAR calculation method. Total higher-order root-mean square increased by a factor 1.18 for Group 1 and 1.6 for Group 2. There was a significant increase of coma by a factor 1.74 in Group 2 and spherical aberration by a factor 2.09 in Group 1 and 3.56 in Group 2. The data support the safety and effectiveness of the wavefront-guided PRK using a WASCA Workstation for correction of low to moderate refractive errors. This method reduced the number of higher order aberrations induced by excimer laser surgery and improved uncorrected and spectacle-corrected visual acuity when compared to conventional PRK.

  14. Interaction between single gold atom and the graphene edge: A study via aberration-corrected transmission electron microscopy

    KAUST Repository

    Wang, Hongtao

    2012-01-01

    Interaction between single noble metal atoms and graphene edges has been investigated via aberration-corrected and monochromated transmission electron microscopy. A collective motion of the Au atom and the nearby carbon atoms is observed in transition between energy-favorable configurations. Most trapping and detrapping processes are assisted by the dangling carbon atoms, which are more susceptible to knock-on displacements by electron irradiation. Thermal energy is lower than the activation barriers in transition among different energy-favorable configurations, which suggests electron-beam irradiation can be an efficient way of engineering the graphene edge with metal atoms. © 2012 The Royal Society of Chemistry.

  15. 3D printing of microlenses for aberration correction in GRIN microendoscopes

    KAUST Repository

    Antonini, Andrea; Bovetti, Serena; Moretti, Claudio; Succol, Francesca; Rajamanickam, Vijayakumar Palanisamy; Bertoncini, Andrea; Fellin, Tommaso; Liberale, Carlo

    2017-01-01

    Two-photon fluorescence microscopy provides high resolution information on the anatomy and function of cellular structures located several hundreds of microns deep within biological tissues. However, light scattering poses a fundamental limit to imaging of deeper areas (> 1.5 mm). Implantable microendoscopic probes based on graded index (GRIN) lenses are widely used tools to perform two-photon fluorescence microscopy in otherwise inaccessible regions[1], but the optical performances of with these probes are limited by intrinsic aberrations.

  16. 3D printing of microlenses for aberration correction in GRIN microendoscopes

    KAUST Repository

    Antonini, Andrea

    2017-11-02

    Two-photon fluorescence microscopy provides high resolution information on the anatomy and function of cellular structures located several hundreds of microns deep within biological tissues. However, light scattering poses a fundamental limit to imaging of deeper areas (> 1.5 mm). Implantable microendoscopic probes based on graded index (GRIN) lenses are widely used tools to perform two-photon fluorescence microscopy in otherwise inaccessible regions[1], but the optical performances of with these probes are limited by intrinsic aberrations.

  17. Self-Correcting Electronically-Scanned Pressure Sensor

    Science.gov (United States)

    Gross, C.; Basta, T.

    1982-01-01

    High-data-rate sensor automatically corrects for temperature variations. Multichannel, self-correcting pressure sensor can be used in wind tunnels, aircraft, process controllers and automobiles. Offers data rates approaching 100,000 measurements per second with inaccuracies due to temperature shifts held below 0.25 percent (nominal) of full scale over a temperature span of 55 degrees C.

  18. Aberration-corrected transmission electron microscopy analyses of GaAs/Si interfaces in wafer-bonded multi-junction solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Häussler, Dietrich [Institute for Materials Science, Christian-Albrechts-University Kiel, Kaiserstraße 2, 24143 Kiel (Germany); Houben, Lothar [Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Research Centre Juelich GmbH, 52425 Juelich (Germany); Essig, Stephanie [Fraunhofer Institute for Solar Energy Systems ISE, Heidenhofstraße 2, 79110 Freiburg (Germany); Kurttepeli, Mert [Institute for Materials Science, Christian-Albrechts-University Kiel, Kaiserstraße 2, 24143 Kiel (Germany); Dimroth, Frank [Fraunhofer Institute for Solar Energy Systems ISE, Heidenhofstraße 2, 79110 Freiburg (Germany); Dunin-Borkowski, Rafal E. [Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Research Centre Juelich GmbH, 52425 Juelich (Germany); Jäger, Wolfgang, E-mail: wolfgang.jaeger@tf.uni-kiel.de [Institute for Materials Science, Christian-Albrechts-University Kiel, Kaiserstraße 2, 24143 Kiel (Germany)

    2013-11-15

    Aberration-corrected scanning transmission electron microscopy (STEM) and electron energy loss spectroscopy (EELS) investigations have been applied to investigate the structure and composition fluctuations near interfaces in wafer-bonded multi-junction solar cells. Multi-junction solar cells are of particular interest since efficiencies well above 40% have been obtained for concentrator solar cells which are based on III-V compound semiconductors. In this methodologically oriented investigation, we explore the potential of combining aberration-corrected high-angle annular dark-field STEM imaging (HAADF-STEM) with spectroscopic techniques, such as EELS and energy-dispersive X-ray spectroscopy (EDXS), and with high-resolution transmission electron microscopy (HR-TEM), in order to analyze the effects of fast atom beam (FAB) and ion beam bombardment (IB) activation treatments on the structure and composition of bonding interfaces of wafer-bonded solar cells on Si substrates. Investigations using STEM/EELS are able to measure quantitatively and with high precision the widths and the fluctuations in element distributions within amorphous interface layers of nanometer extensions, including those of light elements. Such measurements allow the control of the activation treatments and thus support assessing electrical conductivity phenomena connected with impurity and dopant distributions near interfaces for optimized performance of the solar cells. - Highlights: • Aberration-corrected TEM and EELS reveal structural and elemental profiles across GaAs/Si bond interfaces in wafer-bonded GaInP/GaAs/Si - multi-junction solar cells. • Fluctuations in elemental concentration in nanometer-thick amorphous interface layers, including the disrubutions of light elements, are measured using EELS. • The projected widths of the interface layers are determined on the atomic scale from STEM-HAADF measurements. • The effects of atom and ion beam activation treatment on the bonding

  19. Correction of aberrations in beams filling elliptical phase-space areas

    International Nuclear Information System (INIS)

    Wollnik, H.

    1988-01-01

    For the optimization of an optical system it is advantageous to amend the system by a virtual object lens so that the calculation always starts from an upright phase-space distribution. Furthermore, in case of a beam filling an elliptical phase-space volume, the most extreme rays of a beam, filling a parallelogram-like phase-space volume, do not exist, so that the corresponding sum of aberrations is smaller. For an optimization thus corresponding attenuation factors should be taken into accout

  20. Design and commissioning of an aberration-corrected ultrafast spin-polarized low energy electron microscope with multiple electron sources.

    Science.gov (United States)

    Wan, Weishi; Yu, Lei; Zhu, Lin; Yang, Xiaodong; Wei, Zheng; Liu, Jefferson Zhe; Feng, Jun; Kunze, Kai; Schaff, Oliver; Tromp, Ruud; Tang, Wen-Xin

    2017-03-01

    We describe the design and commissioning of a novel aberration-corrected low energy electron microscope (AC-LEEM). A third magnetic prism array (MPA) is added to the standard AC-LEEM with two prism arrays, allowing the incorporation of an ultrafast spin-polarized electron source alongside the standard cold field emission electron source, without degrading spatial resolution. The high degree of symmetries of the AC-LEEM are utilized while we design the electron optics of the ultrafast spin-polarized electron source, so as to minimize the deleterious effect of time broadening, while maintaining full control of electron spin. A spatial resolution of 2nm and temporal resolution of 10ps (ps) are expected in the future time resolved aberration-corrected spin-polarized LEEM (TR-AC-SPLEEM). The commissioning of the three-prism AC-LEEM has been successfully finished with the cold field emission source, with a spatial resolution below 2nm. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. From Nanoparticles to Process An Aberration Corrected TEM Study of Fischer Tropsch Catalysts at Various Steps of the Process

    International Nuclear Information System (INIS)

    Braidy, N.; Blanchard, J.; Abatzoglou, N.; Andrei, C.

    2011-01-01

    χThe nanostructure of Fischer-Tropsch (FT) Fe carbides are investigated using aberration-corrected high-resolution transmission electron microscopy (TEM). The plasma-generated Fe carbides are analyzed just after synthesis, following reduction via a H2 treatment step and once used as FT catalyst and deactivated. The as-produced nanoparticles (NPs) are seen to be abundantly covered with graphitic and amorphous carbon. Using the extended information limit from the spherical aberration-corrected TEM, the NPs could be indexed as a mixture of NPs in the θ-Fe 3 C and χ-Fe 5 C 2 phases. The reduction treatment exposed the NPs by removing most of the carbonaceous speSubscript textcies while retaining the χ-Fe 5 C 2 . Fe-carbides NPs submitted to conditions typical to FT synthesis develop a Fe3O4 shell which eventually consumes the NPs up to a point where 3-4 nm residual carbide is left at the center of the particle. Subscript textVarious mechanisms explaining the formation of such a microstructure are discussed. (author)

  2. Transcranial passive acoustic mapping with hemispherical sparse arrays using CT-based skull-specific aberration corrections: a simulation study

    International Nuclear Information System (INIS)

    Jones, Ryan M; O’Reilly, Meaghan A; Hynynen, Kullervo

    2013-01-01

    The feasibility of transcranial passive acoustic mapping with hemispherical sparse arrays (30 cm diameter, 16 to 1372 elements, 2.48 mm receiver diameter) using CT-based aberration corrections was investigated via numerical simulations. A multi-layered ray acoustic transcranial ultrasound propagation model based on CT-derived skull morphology was developed. By incorporating skull-specific aberration corrections into a conventional passive beamforming algorithm (Norton and Won 2000 IEEE Trans. Geosci. Remote Sens. 38 1337–43), simulated acoustic source fields representing the emissions from acoustically-stimulated microbubbles were spatially mapped through three digitized human skulls, with the transskull reconstructions closely matching the water-path control images. Image quality was quantified based on main lobe beamwidths, peak sidelobe ratio, and image signal-to-noise ratio. The effects on the resulting image quality of the source’s emission frequency and location within the skull cavity, the array sparsity and element configuration, the receiver element sensitivity, and the specific skull morphology were all investigated. The system’s resolution capabilities were also estimated for various degrees of array sparsity. Passive imaging of acoustic sources through an intact skull was shown possible with sparse hemispherical imaging arrays. This technique may be useful for the monitoring and control of transcranial focused ultrasound (FUS) treatments, particularly non-thermal, cavitation-mediated applications such as FUS-induced blood–brain barrier disruption or sonothrombolysis, for which no real-time monitoring techniques currently exist. (paper)

  3. Transcranial passive acoustic mapping with hemispherical sparse arrays using CT-based skull-specific aberration corrections: a simulation study

    Science.gov (United States)

    Jones, Ryan M.; O’Reilly, Meaghan A.; Hynynen, Kullervo

    2013-01-01

    The feasibility of transcranial passive acoustic mapping with hemispherical sparse arrays (30 cm diameter, 16 to 1372 elements, 2.48 mm receiver diameter) using CT-based aberration corrections was investigated via numerical simulations. A multi-layered ray acoustic transcranial ultrasound propagation model based on CT-derived skull morphology was developed. By incorporating skull-specific aberration corrections into a conventional passive beamforming algorithm (Norton and Won 2000 IEEE Trans. Geosci. Remote Sens. 38 1337–43), simulated acoustic source fields representing the emissions from acoustically-stimulated microbubbles were spatially mapped through three digitized human skulls, with the transskull reconstructions closely matching the water-path control images. Image quality was quantified based on main lobe beamwidths, peak sidelobe ratio, and image signal-to-noise ratio. The effects on the resulting image quality of the source’s emission frequency and location within the skull cavity, the array sparsity and element configuration, the receiver element sensitivity, and the specific skull morphology were all investigated. The system’s resolution capabilities were also estimated for various degrees of array sparsity. Passive imaging of acoustic sources through an intact skull was shown possible with sparse hemispherical imaging arrays. This technique may be useful for the monitoring and control of transcranial focused ultrasound (FUS) treatments, particularly non-thermal, cavitation-mediated applications such as FUS-induced blood-brain barrier disruption or sonothrombolysis, for which no real-time monitoring technique currently exists. PMID:23807573

  4. Method and system for automatically correcting aberrations of a beam of charged particles

    International Nuclear Information System (INIS)

    1975-01-01

    The location of a beam of charged particles within a deflection field is determined by its orthogonal deflection voltages. With the location of the beam in the field, correction currents are supplied to a focus coil and to each of a pair of stigmator coils to correct for change of focal length and astigmatism due to the beam being deflected away from the center of its deflection field

  5. Depth-resolution imaging of crystalline nanoclusters attached on and embedded in amorphous films using aberration-corrected TEM

    Energy Technology Data Exchange (ETDEWEB)

    Yamasaki, Jun, E-mail: yamasaki@uhvem.osaka-u.ac.jp [Research Center for Ultra-High Voltage Electron Microscopy, Osaka University, 7-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); EcoTopia Science Institute, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Mori, Masayuki [Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Hirata, Akihiko [Advanced Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); Hirotsu, Yoshihiko [Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Tanaka, Nobuo [EcoTopia Science Institute, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan)

    2015-04-15

    For observations of crystalline nanoclusters, the features and capabilities of depth-resolution imaging by aberration-corrected transmission electron microscopy (TEM) were investigated using image simulations and experiments for two types of samples. The first sample was gold clusters attached on an amorphous carbon film. The experimental through-focal series indicated that the focal plane for the cluster was shifted 3 nm from that for the supporting film. This difference is due to the depth-resolution imaging of the cluster and film, the mid-planes of which are separated by 3 nm along the depth direction (the electron incident direction). On the basis of this information, the three-dimensional configuration of the sample, such as the film thickness of 2 nm, was successfully illustrated. The second sample was a Zr{sub 66.7}Ni{sub 33.3} metallic glass including a medium-range-order (MRO) structure, which was approximately considered to be a crystalline cluster with a diameter of 1.6 nm. In the experimental through-focal series, the lattice fringe of the MRO cluster was visible at limited focal conditions. Image simulations reproduced well the focal conditions and also indicated a structural condition for the visualization that the embedded cluster must be apart from the mid-plane of the matrix film. Similar to the case of the first sample, this result can be explained by the idea that the “effective focal planes” for the film and cluster are at different heights. This type of depth-resolution phase contrast imaging is possible only in aberration-corrected TEM and when the sample has a simple structure and is sufficiently thin for the kinematical scattering approximation. - Highlights: • Depth-resolution imaging by aberration-corrected TEM was demonstrated. • Thickness of a carbon film supporting gold nano-crystals was successfully estimated. • A crystalline nanocluster embedded in an amorphous matrix was successfully observed. • It was clarified that

  6. Online correction of scanning probe microscopes with pixel accuracy

    DEFF Research Database (Denmark)

    Dirscherl, Kai

    2000-01-01

    of 10 nm and an opening angle of 30.0 °. Even atomic resolution can be achieved. The scan movement of the tip is not linear however. This is caused by the propelling device of the SPM for the scan motion - a piezoelectric ceramic. The two major non-linear responses o f the piezo to the applied control....... The algorithm typically contains 5 - 7 parameters which have to be calibrated manually. Still, non-linear errors remain in the order of 1-2%. One pixel in a 512x 512 image corresponds to 0.2% per direction. This goal of measurement accuracy i s reached with the algorithm developed in this thesis. Three...... different SPM are analyzed for their non-linearity. Two commercial tube sc anners are applied with a maximum scan range in x and y of 40.0 µm and 160.0 µm as well as one specially designed stack scanner with a maximum range of 5.0 µm. For the tube scanners, a 1-dimensional line pattern with a reference...

  7. Reduction of variance in spectral estimates for correction of ultrasonic aberration.

    Science.gov (United States)

    Astheimer, Jeffrey P; Pilkington, Wayne C; Waag, Robert C

    2006-01-01

    A variance reduction factor is defined to describe the rate of convergence and accuracy of spectra estimated from overlapping ultrasonic scattering volumes when the scattering is from a spatially uncorrelated medium. Assuming that the individual volumes are localized by a spherically symmetric Gaussian window and that centers of the volumes are located on orbits of an icosahedral rotation group, the factor is minimized by adjusting the weight and radius of each orbit. Conditions necessary for the application of the variance reduction method, particularly for statistical estimation of aberration, are examined. The smallest possible value of the factor is found by allowing an unlimited number of centers constrained only to be within a ball rather than on icosahedral orbits. Computations using orbits formed by icosahedral vertices, face centers, and edge midpoints with a constraint radius limited to a small multiple of the Gaussian width show that a significant reduction of variance can be achieved from a small number of centers in the confined volume and that this reduction is nearly the maximum obtainable from an unlimited number of centers in the same volume.

  8. Error analysis of motion correction method for laser scanning of moving objects

    Science.gov (United States)

    Goel, S.; Lohani, B.

    2014-05-01

    The limitation of conventional laser scanning methods is that the objects being scanned should be static. The need of scanning moving objects has resulted in the development of new methods capable of generating correct 3D geometry of moving objects. Limited literature is available showing development of very few methods capable of catering to the problem of object motion during scanning. All the existing methods utilize their own models or sensors. Any studies on error modelling or analysis of any of the motion correction methods are found to be lacking in literature. In this paper, we develop the error budget and present the analysis of one such `motion correction' method. This method assumes availability of position and orientation information of the moving object which in general can be obtained by installing a POS system on board or by use of some tracking devices. It then uses this information along with laser scanner data to apply correction to laser data, thus resulting in correct geometry despite the object being mobile during scanning. The major application of this method lie in the shipping industry to scan ships either moving or parked in the sea and to scan other objects like hot air balloons or aerostats. It is to be noted that the other methods of "motion correction" explained in literature can not be applied to scan the objects mentioned here making the chosen method quite unique. This paper presents some interesting insights in to the functioning of "motion correction" method as well as a detailed account of the behavior and variation of the error due to different sensor components alone and in combination with each other. The analysis can be used to obtain insights in to optimal utilization of available components for achieving the best results.

  9. Lowered threshold energy for femtosecond laser induced optical breakdown in a water based eye model by aberration correction with adaptive optics.

    Science.gov (United States)

    Hansen, Anja; Géneaux, Romain; Günther, Axel; Krüger, Alexander; Ripken, Tammo

    2013-06-01

    In femtosecond laser ophthalmic surgery tissue dissection is achieved by photodisruption based on laser induced optical breakdown. In order to minimize collateral damage to the eye laser surgery systems should be optimized towards the lowest possible energy threshold for photodisruption. However, optical aberrations of the eye and the laser system distort the irradiance distribution from an ideal profile which causes a rise in breakdown threshold energy even if great care is taken to minimize the aberrations of the system during design and alignment. In this study we used a water chamber with an achromatic focusing lens and a scattering sample as eye model and determined breakdown threshold in single pulse plasma transmission loss measurements. Due to aberrations, the precise lower limit for breakdown threshold irradiance in water is still unknown. Here we show that the threshold energy can be substantially reduced when using adaptive optics to improve the irradiance distribution by spatial beam shaping. We found that for initial aberrations with a root-mean-square wave front error of only one third of the wavelength the threshold energy can still be reduced by a factor of three if the aberrations are corrected to the diffraction limit by adaptive optics. The transmitted pulse energy is reduced by 17% at twice the threshold. Furthermore, the gas bubble motions after breakdown for pulse trains at 5 kilohertz repetition rate show a more transverse direction in the corrected case compared to the more spherical distribution without correction. Our results demonstrate how both applied and transmitted pulse energy could be reduced during ophthalmic surgery when correcting for aberrations. As a consequence, the risk of retinal damage by transmitted energy and the extent of collateral damage to the focal volume could be minimized accordingly when using adaptive optics in fs-laser surgery.

  10. Experimental demonstration of passive acoustic imaging in the human skull cavity using CT-based aberration corrections.

    Science.gov (United States)

    Jones, Ryan M; O'Reilly, Meaghan A; Hynynen, Kullervo

    2015-07-01

    Experimentally verify a previously described technique for performing passive acoustic imaging through an intact human skull using noninvasive, computed tomography (CT)-based aberration corrections Jones et al. [Phys. Med. Biol. 58, 4981-5005 (2013)]. A sparse hemispherical receiver array (30 cm diameter) consisting of 128 piezoceramic discs (2.5 mm diameter, 612 kHz center frequency) was used to passively listen through ex vivo human skullcaps (n = 4) to acoustic emissions from a narrow-band fixed source (1 mm diameter, 516 kHz center frequency) and from ultrasound-stimulated (5 cycle bursts, 1 Hz pulse repetition frequency, estimated in situ peak negative pressure 0.11-0.33 MPa, 306 kHz driving frequency) Definity™ microbubbles flowing through a thin-walled tube phantom. Initial in vivo feasibility testing of the method was performed. The performance of the method was assessed through comparisons to images generated without skull corrections, with invasive source-based corrections, and with water-path control images. For source locations at least 25 mm from the inner skull surface, the modified reconstruction algorithm successfully restored a single focus within the skull cavity at a location within 1.25 mm from the true position of the narrow-band source. The results obtained from imaging single bubbles are in good agreement with numerical simulations of point source emitters and the authors' previous experimental measurements using source-based skull corrections O'Reilly et al. [IEEE Trans. Biomed. Eng. 61, 1285-1294 (2014)]. In a rat model, microbubble activity was mapped through an intact human skull at pressure levels below and above the threshold for focused ultrasound-induced blood-brain barrier opening. During bursts that led to coherent bubble activity, the location of maximum intensity in images generated with CT-based skull corrections was found to deviate by less than 1 mm, on average, from the position obtained using source-based corrections. Taken

  11. Method and system for correcting an aberration of a beam of charged particles

    International Nuclear Information System (INIS)

    1975-01-01

    A beam of charged particles is deflected in a closed path such as a square over a cross wire grid, for example, at a constant velocity by an X Y deflection system. A small high frequency jitter is added at both axes of deflection to cause oscillation of the beam at 45deg to the X and Y axes. From the time that the leading edge of the oscillating beam passes over the wire until the trailing edge of the beam passes over the wire, an envelope of the oscillations produced by the jitter is obtained. A second envelope is obtained when the leading edge of the beam exits from being over the wire until the trailing edge of the beam ceases to be over the wire. Thus, a pair of envelopes is produced as the beam passes over each wire of the grid. The number of pulses exceeding ten percent of the peak voltage in the eight envelopes produced by the beam completing a cycle in its closed path around the grid are counted and compared with those counted during the previous cycle of the beam moving in its closed path over the grid. As the number of pulses decreases, the quality of the focus of the beam increases so that correction signals are applied to the focus coil in accordance with whether the number of pulses is increasing or decreasing

  12. Method and system for correcting an aberration of a beam of charged particles

    Energy Technology Data Exchange (ETDEWEB)

    1975-06-20

    A beam of charged particles is deflected in a closed path such as a square over a cross wire grid, for example, at a constant velocity by an X Y deflection system. A small high frequency jitter is added at both axes of deflection to cause oscillation of the beam at 45deg to the X and Y axes. From the time that the leading edge of the oscillating beam passes over the wire until the trailing edge of the beam passes over the wire, an envelope of the oscillations produced by the jitter is obtained. A second envelope is obtained when the leading edge of the beam exits from being over the wire until the trailing edge of the beam ceases to be over the wire. Thus, a pair of envelopes is produced as the beam passes over each wire of the grid. The number of pulses exceeding ten percent of the peak voltage in the eight envelopes produced by the beam completing a cycle in its closed path around the grid are counted and compared with those counted during the previous cycle of the beam moving in its closed path over the grid. As the number of pulses decreases, the quality of the focus of the beam increases so that correction signals are applied to the focus coil in accordance with whether the number of pulses is increasing or decreasing.

  13. Correção das aberrações oculares nos retratamentos de LASIK personalizado e convencional Correction of ocular aberrations in custom and standard LASIK retreatments

    Directory of Open Access Journals (Sweden)

    Andréia Peltier Urbano

    2009-10-01

    Full Text Available OBJETIVO: Comparar a correção das aberrações oculares nos retratamentos de LASIK personalizado e convencional. MÉTODOS: Foi realizado um estudo prospectivo, randomizado, de 74 olhos de 37 pacientes submetidos ao retratamento de LASIK para correção de miopia e astigmatismo. Cada paciente foi submetido ao retratamento de LASIK personalizado Zyoptix (Bausch & Lomb em um olho e convencional Planoscan (Bausch & Lomb no olho contralateral. Foi comparada a correção das aberrações oculares nos retratamentos personalizado e convencional. RESULTADOS: No sexto mês pós-operatório, os olhos submetidos ao retratamento Zyoptix apresentaram diminuição estatisticamente significativa do defocus, astigmatismo, coma, aberração esférica, segunda ordem, terceira ordem, alta ordem e aberrações totais. Os olhos submetidos ao retratamento Planoscan apresentaram diminuição estatisticamente significativa do defocus, segunda ordem e aberrações totais. CONCLUSÕES: O retratamento personalizado foi superior ao retratamento convencional para a correção das aberrações oculares de baixa e alta ordens.PURPOSE: To compare the correction of ocular aberrations between custom and standard LASIK retreatment. METHODS: Prospective, randomized trial with paired eye control of 74 eyes from 37 patients who underwent LASIK retreatment. Each patient underwent retreatment using Zyoptix LASIK (Bausch & Lomb in 1 eye and Planoscan LASIK (Bausch & Lomb in the fellow eye. Correction of ocular aberrations was compared between custom and standard LASIK retreatments. RESULTS: At 6 months, there was a statistically significant reduction in defocus, astigmatism, coma, spherical aberration, second, third, higher-order and total aberration in Zyoptix eyes. There was a statistically significant reduction in defocus, second-order and total aberration in Planoscan eyes. CONCLUSIONS: Custom retreatment was statistically superior than standard retreatment for correction of lower

  14. Wavefront correction for static and dynamic aberrations to within 1 second of the system shot in the NIF Beamlet demonstration facility

    International Nuclear Information System (INIS)

    Hartley, R.; Kartz, M.; Behrendt, W.

    1996-10-01

    The laser wavefront of the NIF Beamlet demonstration system is corrected for static aberrations with a wavefront control system. The system operates closed loop with a probe beam prior to a shot and has a loop bandwidth of about 3 Hz. However, until recently the wavefront control system was disabled several minutes prior to the shot to allow time to manually reconfigure its attenuators and probe beam insertion mechanism to shot mode. Thermally-induced dynamic variations in gas density in the Beamlet main beam line produce significant wavefront error. After about 5-8 seconds, the wavefront error has increased to a new, higher level due to turbulence- induced aberrations no longer being corrected- This implies that there is a turbulence-induced aberration noise bandwidth of less than one Hertz, and that the wavefront controller could correct for the majority of turbulence-induced aberration (about one- third wave) by automating its reconfiguration to occur within one second of the shot, This modification was recently implemented on Beamlet; we call this modification the t 0 -1 system

  15. Aberration corrected and 3D cryo-tomography HAADF-STEM surface studies of ZnO tetrapods

    International Nuclear Information System (INIS)

    Ward, M R; Gai, P L; Boyes, E D; Sugiura, H; Tanaka, N; Yoshida, K

    2012-01-01

    We present a morphology study of ZnO tetrapods using aberration corrected TEM, HAADF-STEM and 3D HAADF-STEM cryotomography as an alternative to more conventional TEM and SEM techniques. We use 3D IMOD reconstructions to show that the {11-bar 0} facets dominate the total surface area of uniform hexagonal prism tetrapods. Using HRTEM we show that the small tetrapods have a zincblende phase core from which the four legs extend. The facets and the edges of these legs were found to be atomically clean and flat with the potential for ZnO tetrapods as model substrates. We deposited ultrafine Pt/Pd nanoparticles onto the tetrapods and investigated the resulting morphologies. We found using HAADF-STEM cryotomography and reconstruction techniques that the nanoparticle coverage gave separate nanoparticles and overall uniform coverage. We believe these techniques and the results from them could be useful for the development of nanoparticle-ZnO tetrapod composite systems with applications in optoelectronics, gas sensing and catalysis.

  16. Atomic resolution imaging of YAlO{sub 3}: Ce in the chromatic and spherical aberration corrected PICO electron microscope

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Lei [Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Jülich-Aachen Research Alliance (JARA), Forschungszentrum Jülich GmbH, 52425 Jülich (Germany); Barthel, Juri [Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Jülich-Aachen Research Alliance (JARA), Forschungszentrum Jülich GmbH, 52425 Jülich (Germany); Central Facility for Electron Microscopy, RWTH Aachen University, 52074 Aachen (Germany); Jia, Chun-Lin [Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Jülich-Aachen Research Alliance (JARA), Forschungszentrum Jülich GmbH, 52425 Jülich (Germany); School of Electronic and Information Engineering and State Key Laboratory for Mechanical Behaviour of Materials, Xi' an Jiaotong University, Xi' an 710049 (China); Urban, Knut W., E-mail: k.urban@fz-juelich.de [Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Jülich-Aachen Research Alliance (JARA), Forschungszentrum Jülich GmbH, 52425 Jülich, (Germany); School of Electronic and Information Engineering and State Key Laboratory for Mechanical Behaviour of Materials, Xi' an Jiaotong University, Xi' an 710049 (China)

    2017-05-15

    Highlights: • First time resolution of 57 pm atom separations by HRTEM with 200 keV electrons. • Quantification of the image spread by absolute matching of experiment and simulation. • An information limit of 52 pm is deduced from the determined image spread. • Substantial deviations from the bulk structure are observed for the ultra-thin sample. - Abstract: The application of combined chromatic and spherical aberration correction in high-resolution transmission electron microscopy enables a significant improvement of the spatial resolution down to 50 pm. We demonstrate that such a resolution can be achieved in practice at 200 kV. Diffractograms of images of gold nanoparticles on amorphous carbon demonstrate corresponding information transfer. The Y atom pairs in [010] oriented yttrium orthoaluminate are successfully imaged together with the Al and the O atoms. Although the 57 pm pair separation is well demonstrated separations between 55 pm and 80 pm are measured. This observation is tentatively attributed to structural relaxations and surface reconstruction in the very thin samples used. Quantification of the resolution limiting effective image spread is achieved based on an absolute match between experimental and simulated image intensity distributions.

  17. Electron-beam-induced-current and active secondary-electron voltage-contrast with aberration-corrected electron probes

    Energy Technology Data Exchange (ETDEWEB)

    Han, Myung-Geun, E-mail: mghan@bnl.gov [Condensed Matter Physics & Materials Science, Brookhaven National Laboratory, Upton, NY 11973 (United States); Garlow, Joseph A. [Condensed Matter Physics & Materials Science, Brookhaven National Laboratory, Upton, NY 11973 (United States); Materials Science and Engineering Department, Stony Brook University, Stony Brook, NY 11794 (United States); Marshall, Matthew S.J.; Tiano, Amanda L. [Department of Chemistry, Stony Brook University, Stony Brook, NY 11974 (United States); Wong, Stanislaus S. [Condensed Matter Physics & Materials Science, Brookhaven National Laboratory, Upton, NY 11973 (United States); Department of Chemistry, Stony Brook University, Stony Brook, NY 11974 (United States); Cheong, Sang-Wook [Department of Physics and Astronomy, Rutgers Center for Emergent Materials, Rutgers University, Piscataway, NJ 08854 (United States); Walker, Frederick J.; Ahn, Charles H. [Department of Applied Physics and Center for Research on Interface Structures and Phenomena, Yale University, New Haven, CT 06520 (United States); Department of Mechanical Engineering and Materials Science, Yale University, New Haven, CT 06520 (United States); Zhu, Yimei [Condensed Matter Physics & Materials Science, Brookhaven National Laboratory, Upton, NY 11973 (United States)

    2017-05-15

    Highlights: • Electron-beam-induced-current (EBIC) and active secondary-electron voltage-contrast (SE-VC) are demonstrated in STEM mode combined with in situ electrical biasing in a TEM. • Electrostatic potential maps in ferroelectric thin films, multiferroic nanowires, and single crystals obtained by off-axis electron holography were compared with EBIC and SE-VC data. • Simultaneous EBIC and active SE-VC performed with atomic resolution STEM are demonstrated. - Abstract: The ability to map out electrostatic potentials in materials is critical for the development and the design of nanoscale electronic and spintronic devices in modern industry. Electron holography has been an important tool for revealing electric and magnetic field distributions in microelectronics and magnetic-based memory devices, however, its utility is hindered by several practical constraints, such as charging artifacts and limitations in sensitivity and in field of view. In this article, we report electron-beam-induced-current (EBIC) and secondary-electron voltage-contrast (SE-VC) with an aberration-corrected electron probe in a transmission electron microscope (TEM), as complementary techniques to electron holography, to measure electric fields and surface potentials, respectively. These two techniques were applied to ferroelectric thin films, multiferroic nanowires, and single crystals. Electrostatic potential maps obtained by off-axis electron holography were compared with EBIC and SE-VC to show that these techniques can be used as a complementary approach to validate quantitative results obtained from electron holography analysis.

  18. Attainment of 40.5 pm spatial resolution using 300 kV scanning transmission electron microscope equipped with fifth-order aberration corrector.

    Science.gov (United States)

    Morishita, Shigeyuki; Ishikawa, Ryo; Kohno, Yuji; Sawada, Hidetaka; Shibata, Naoya; Ikuhara, Yuichi

    2018-02-01

    The achievement of a fine electron probe for high-resolution imaging in scanning transmission electron microscopy requires technological developments, especially in electron optics. For this purpose, we developed a microscope with a fifth-order aberration corrector that operates at 300 kV. The contrast flat region in an experimental Ronchigram, which indicates the aberration-free angle, was expanded to 70 mrad. By using a probe with convergence angle of 40 mrad in the scanning transmission electron microscope at 300 kV, we attained the spatial resolution of 40.5 pm, which is the projected interatomic distance between Ga-Ga atomic columns of GaN observed along [212] direction.

  19. 3D scanning based mold correction for planar and cylindrical parts in aluminum die casting

    Directory of Open Access Journals (Sweden)

    Takashi Seno

    2015-04-01

    Full Text Available Aluminum die casting is an important manufacturing process for mechanical components. Die casting is known to be more accurate than other types of casting; however, post-machining is usually necessary to achieve the required accuracy. The goal of this investigation is to develop machining- free aluminum die casting. Improvement of the accuracy of planar and cylindrical parts is expected by correcting metal molds. In the proposed method, the shape of cast aluminum made with the initial metal molds is measured by 3D scanning. The 3D scan data includes information about deformations that occur during casting. Therefore, it is possible to estimate the deformation and correction amounts by comparing 3D scan data with product computer-aided design (CAD data. We corrected planar and cylindrical parts of the CAD data for the mold. In addition, we corrected the planar part of the metal mold using the corrected mold data. The effectiveness of the proposed method is demonstrated by evaluating the accuracy improvement of the cast aluminum made with the corrected mold.

  20. Aberration corrected STEM of defects in epitaxial n=4 Ruddlesden-Popper phase Can+1MnnO3n+1

    International Nuclear Information System (INIS)

    Wang, P; Bleloch, A L; Goodhew, P J; Yan, L; Niu, H J; Rosseinsky, M J; Chalker, P R

    2008-01-01

    Defects in Ruddlesden-Popper phase CaO·[(CaMnO 3 )] 4 epitaxial films grown on SrTiO 3 (001) by pulsed laser deposition have been investigated using high angle annular dark field imaging in an aberration-corrected STEM. The stacking faults perpendicular and parallel to the substrate formed during the growth are discussed in detail. The desired n = 4 RP phase is imaged and chemically analyzed at the atomic scale using electron energy loss spectroscopy.

  1. Scatter measurement and correction method for cone-beam CT based on single grating scan

    Science.gov (United States)

    Huang, Kuidong; Shi, Wenlong; Wang, Xinyu; Dong, Yin; Chang, Taoqi; Zhang, Hua; Zhang, Dinghua

    2017-06-01

    In cone-beam computed tomography (CBCT) systems based on flat-panel detector imaging, the presence of scatter significantly reduces the quality of slices. Based on the concept of collimation, this paper presents a scatter measurement and correction method based on single grating scan. First, according to the characteristics of CBCT imaging, the scan method using single grating and the design requirements of the grating are analyzed and figured out. Second, by analyzing the composition of object projection images and object-and-grating projection images, the processing method for the scatter image at single projection angle is proposed. In addition, to avoid additional scan, this paper proposes an angle interpolation method of scatter images to reduce scan cost. Finally, the experimental results show that the scatter images obtained by this method are accurate and reliable, and the effect of scatter correction is obvious. When the additional object-and-grating projection images are collected and interpolated at intervals of 30 deg, the scatter correction error of slices can still be controlled within 3%.

  2. Safety, efficacy, and predictability of laser in situ keratomileusis to correct myopia or myopic astigmatism with a 750 Hz scanning-spot laser system.

    Science.gov (United States)

    Tomita, Minoru; Watabe, Miyuki; Yukawa, Satoshi; Nakamura, Nobuo; Nakamura, Tadayuki; Magnago, Thomas

    2014-02-01

    To evaluate the clinical outcomes of laser in situ keratomileusis (LASIK) to correct myopia or myopic astigmatism using the Amaris 750S 750 Hz excimer laser. Private LASIK center, Tokyo, Japan. Case series. Patients with myopia or myopic astigmatism (spherical equivalent -0.50 to -11.63 diopters [D]), a corrected distance visual acuity (CDVA) of 20/20 or better, and an estimated residual bed thickness of 300 μm or more had LASIK using the aspheric aberration-free ablation profile of the 750 Hz scanning-spot laser and the Femto LDV Crystal Line femtosecond laser for flap creation. Study parameters included uncorrected distance visual acuity (UDVA), CDVA, manifest refraction, astigmatism, and higher-order aberrations (HOAs). The study included 1280 eyes (685 patients). At 3 months, 96.6% of eyes had a UDVA of 20/20 or better and 99.1% had 20/32 or better; 94.1% of eyes were within ± 0.50 D of the intended correction and 98.9% were within ± 1.00 D; 89.7% of eyes had no residual cylinder and 96.0% had a postoperative astigmatism of less than 0.50 D. All eyes had a postoperative CDVA of 20/20 or better. The HOAs increased postoperatively (PLaser in situ keratomileusis with the 750 Hz scanning-spot laser was safe, effective, and predictable. No specific clinical side effects that might be associated with a high repetition rate occurred. Mr. Magnago is an employee of Schwind eye-tech-solutions GmbH. No other author has a financial or proprietary interest in any material or method mentioned. Copyright © 2013 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  3. Real-time scanning charged-particle microscope image composition with correction of drift.

    Science.gov (United States)

    Cizmar, Petr; Vladár, András E; Postek, Michael T

    2011-04-01

    In this article, a new scanning electron microscopy (SEM) image composition technique is described, which can significantly reduce drift related image corruptions. Drift distortion commonly causes blur and distortions in the SEM images. Such corruption ordinarily appears when conventional image-acquisition methods, i.e., "slow scan" and "fast scan," are applied. The damage is often very significant; it may render images unusable for metrology applications, especially where subnanometer accuracy is required. The described correction technique works with a large number of quickly taken frames, which are properly aligned and then composed into a single image. Such image contains much less noise than the individual frames, while the blur and deformation is minimized. This technique also provides useful information about changes of the sample position in time, which may be applied to investigate the drift properties of the instrument without a need of additional equipment.

  4. Reply to L.M. Brown et al. “Brief history of the Cambridge STEM aberration correction project and its progeny” in Ultramicroscopy 157, 88 (2015)

    Energy Technology Data Exchange (ETDEWEB)

    Urban, K.W., E-mail: k.urban@fz-juelich.de [Peter Grünberg Institute, Forschungszentrum Jülich, Jülich-Aachen Research Alliance (JARA), and Ernst Ruska Centre for Microscopy and Spectroscopy with Electrons, 52425 Jülich (Germany); Rose, H. [Materialwissenschaftliche Elektronenmikroskopie, Universität Ulm, Albert-Einstein-Allee 11, 89081 Ulm (Germany)

    2016-02-15

    We comment on a Short Communication recently published in Ultramicroscopy in which Brown et al. criticize our description of the time sequence of events in the development of aberration correction systems in electron optics during the 1990s put forward in the introduction to the Ultramicroscopy April 2015 Special Issue. We present an analysis of the published literature furnishing evidence that our description is correct. - Highlights: • We scrutinize assertions made on the evolution of Cambridge Cs corrector project. • References [22-24] do not demonstrate improvement of resolution by Cs correction. • According to literature such improvement is only shown in reference [10] in 2001. • Corresponding evidence was published by Heidelberg project already in 1998. • The Heidelberg Cs corrector project antedates the Cambridge project by 3 years.

  5. Reply to L.M. Brown et al. “Brief history of the Cambridge STEM aberration correction project and its progeny” in Ultramicroscopy 157, 88 (2015)

    International Nuclear Information System (INIS)

    Urban, K.W.; Rose, H.

    2016-01-01

    We comment on a Short Communication recently published in Ultramicroscopy in which Brown et al. criticize our description of the time sequence of events in the development of aberration correction systems in electron optics during the 1990s put forward in the introduction to the Ultramicroscopy April 2015 Special Issue. We present an analysis of the published literature furnishing evidence that our description is correct. - Highlights: • We scrutinize assertions made on the evolution of Cambridge Cs corrector project. • References [22-24] do not demonstrate improvement of resolution by Cs correction. • According to literature such improvement is only shown in reference [10] in 2001. • Corresponding evidence was published by Heidelberg project already in 1998. • The Heidelberg Cs corrector project antedates the Cambridge project by 3 years.

  6. Reduced sintering of mass-selected Au clusters on SiO2 by alloying with Ti: an aberration-corrected STEM and computational study

    DEFF Research Database (Denmark)

    Niu, Yubiao; Schlexer, Philomena; Sebök, Béla

    2018-01-01

    with a reactive metal, Ti. Mass-selected Au/Ti clusters (400 000 amu) and Au2057 clusters (405 229 amu) were produced with a magnetron sputtering, gas condensation cluster beam source in conjunction with a lateral time-of-flight mass filter, deposited onto a silica support and characterised by XPS and LEIS....... The sintering dynamics of mass-selected Au and Au/Ti alloy nanoclusters were investigated in real space and real time with atomic resolution aberration-corrected HAADF-STEM imaging, supported by model DFT calculations. A strong anchoring effect was revealed in the case of the Au/Ti clusters, because of a much...

  7. Three-Dimensional scanning transmission electron microscopy of biological specimens

    KAUST Repository

    De Jonge, Niels; Sougrat, Rachid; Northan, Brian M.; Pennycook, Stephen J.

    2010-01-01

    A three-dimensional (3D) reconstruction of the cytoskeleton and a clathrin-coated pit in mammalian cells has been achieved from a focal-series of images recorded in an aberration-corrected scanning transmission electron microscope (STEM

  8. Adaptive compensation of aberrations in ultrafast 3D microscopy using a deformable mirror

    Science.gov (United States)

    Sherman, Leah R.; Albert, O.; Schmidt, Christoph F.; Vdovin, Gleb V.; Mourou, Gerard A.; Norris, Theodore B.

    2000-05-01

    3D imaging using a multiphoton scanning confocal microscope is ultimately limited by aberrations of the system. We describe a system to adaptively compensate the aberrations with a deformable mirror. We have increased the transverse scanning range of the microscope by three with compensation of off-axis aberrations.We have also significantly increased the longitudinal scanning depth with compensation of spherical aberrations from the penetration into the sample. Our correction is based on a genetic algorithm that uses second harmonic or two-photon fluorescence signal excited by femtosecond pulses from the sample as the enhancement parameter. This allows us to globally optimize the wavefront without a wavefront measurement. To improve the speed of the optimization we use Zernike polynomials as the basis for correction. Corrections can be stored in a database for look-up with future samples.

  9. Dual ring multilayer ionization chamber and theory-based correction technique for scanning proton therapy.

    Science.gov (United States)

    Takayanagi, Taisuke; Nihongi, Hideaki; Nishiuchi, Hideaki; Tadokoro, Masahiro; Ito, Yuki; Nakashima, Chihiro; Fujitaka, Shinichiro; Umezawa, Masumi; Matsuda, Koji; Sakae, Takeji; Terunuma, Toshiyuki

    2016-07-01

    To develop a multilayer ionization chamber (MLIC) and a correction technique that suppresses differences between the MLIC and water phantom measurements in order to achieve fast and accurate depth dose measurements in pencil beam scanning proton therapy. The authors distinguish between a calibration procedure and an additional correction: 1-the calibration for variations in the air gap thickness and the electrometer gains is addressed without involving measurements in water; 2-the correction is addressed to suppress the difference between depth dose profiles in water and in the MLIC materials due to the nuclear interaction cross sections by a semiempirical model tuned by using measurements in water. In the correction technique, raw MLIC data are obtained for each energy layer and integrated after multiplying them by the correction factor because the correction factor depends on incident energy. The MLIC described here has been designed especially for pencil beam scanning proton therapy. This MLIC is called a dual ring multilayer ionization chamber (DRMLIC). The shape of the electrodes allows the DRMLIC to measure both the percentage depth dose (PDD) and integrated depth dose (IDD) because ionization electrons are collected from inner and outer air gaps independently. IDDs for which the beam energies were 71.6, 120.6, 159, 180.6, and 221.4 MeV were measured and compared with water phantom results. Furthermore, the measured PDDs along the central axis of the proton field with a nominal field size of 10 × 10 cm(2) were compared. The spread out Bragg peak was 20 cm for fields with a range of 30.6 and 3 cm for fields with a range of 6.9 cm. The IDDs measured with the DRMLIC using the correction technique were consistent with those that of the water phantom; except for the beam energy of 71.6 MeV, all of the points satisfied the 1% dose/1 mm distance to agreement criterion of the gamma index. The 71.6 MeV depth dose profile showed slight differences in the shallow

  10. Dual ring multilayer ionization chamber and theory-based correction technique for scanning proton therapy

    International Nuclear Information System (INIS)

    Takayanagi, Taisuke; Nishiuchi, Hideaki; Fujitaka, Shinichiro; Umezawa, Masumi; Nihongi, Hideaki; Tadokoro, Masahiro; Ito, Yuki; Nakashima, Chihiro; Matsuda, Koji; Sakae, Takeji; Terunuma, Toshiyuki

    2016-01-01

    Purpose: To develop a multilayer ionization chamber (MLIC) and a correction technique that suppresses differences between the MLIC and water phantom measurements in order to achieve fast and accurate depth dose measurements in pencil beam scanning proton therapy. Methods: The authors distinguish between a calibration procedure and an additional correction: 1—the calibration for variations in the air gap thickness and the electrometer gains is addressed without involving measurements in water; 2—the correction is addressed to suppress the difference between depth dose profiles in water and in the MLIC materials due to the nuclear interaction cross sections by a semiempirical model tuned by using measurements in water. In the correction technique, raw MLIC data are obtained for each energy layer and integrated after multiplying them by the correction factor because the correction factor depends on incident energy. The MLIC described here has been designed especially for pencil beam scanning proton therapy. This MLIC is called a dual ring multilayer ionization chamber (DRMLIC). The shape of the electrodes allows the DRMLIC to measure both the percentage depth dose (PDD) and integrated depth dose (IDD) because ionization electrons are collected from inner and outer air gaps independently. Results: IDDs for which the beam energies were 71.6, 120.6, 159, 180.6, and 221.4 MeV were measured and compared with water phantom results. Furthermore, the measured PDDs along the central axis of the proton field with a nominal field size of 10 × 10 cm 2 were compared. The spread out Bragg peak was 20 cm for fields with a range of 30.6 and 3 cm for fields with a range of 6.9 cm. The IDDs measured with the DRMLIC using the correction technique were consistent with those that of the water phantom; except for the beam energy of 71.6 MeV, all of the points satisfied the 1% dose/1 mm distance to agreement criterion of the gamma index. The 71.6 MeV depth dose profile showed slight

  11. Poster - 17: Characterization and correction of radiation induced background in scanning water tanks

    Energy Technology Data Exchange (ETDEWEB)

    Ali, Elsayed [The Ottawa Hospital Cancer Centre (Canada)

    2016-08-15

    Purpose: To characterize and correct for radiation-induced background (RIB) observed in the signals from a class of scanning water tanks. Methods: A method was developed to isolate the RIB through detector measurements in the background-free linac console area. Variation of the RIB against a large number of parameters was characterized, and its impact on basic clinical data for photon and electron beams was quantified. Different methods to minimize and/or correct for the RIB were proposed and evaluated. Results: The RIB is due to the presence of the electrometer and connection box in a low background radiation field (by design). The absolute RIB current with a biased detector is up to 2 pA, independent of the detector size, which is 0.6% and 1.5% of the central axis reference signal for a standard and a mini scanning chamber, respectively. The RIB monotonically increases with field size, is three times smaller for detectors that do not require a bias (e.g., diodes), is up to 80% larger for positive (versus negative) polarity, decreases with increasing photon energy, exhibits a single curve versus dose rate at the electrometer location, and is negligible for electron beams. Data after the proposed field-size correction method agree with point measurements from an independent system to within a few tenth of a percent for output factor, head scatter, depth dose at depth, and out-of-field profile dose. Manufacturer recommendations for electrometer placement are insufficient and sometimes incorrect. Conclusions: RIB in scanning water tanks can have a non-negligible effect on dosimetric data.

  12. On the Frequency Correction in Temperature-Modulated Differential Scanning Calorimetry of Glass Transition

    DEFF Research Database (Denmark)

    Guo, Xiaoju; Mauro, J.C.; Allan, D.C.

    2012-01-01

    Temperature-modulated differential scanning calorimetry (TMDSC) is based on conventional DSC but with a sinusoidally modulated temperature path. Simulations of TMDSC signals were performed for Corning EAGLE XG® glass over a wide range of modulation frequencies. Our results reveal that the frequency...... correction commonly used in the interpretation of TMDSC signals leads to a master nonreversing heat flow curve independent of modulation frequency, provided that sufficiently high frequencies are employed in the TMDSC measurement. A master reversing heat flow curve can also be generated through the frequency...

  13. Optical traps with geometric aberrations

    International Nuclear Information System (INIS)

    Roichman, Yael; Waldron, Alex; Gardel, Emily; Grier, David G.

    2006-01-01

    We assess the influence of geometric aberrations on the in-plane performance of optical traps by studying the dynamics of trapped colloidal spheres in deliberately distorted holographic optical tweezers. The lateral stiffness of the traps turns out to be insensitive to moderate amounts of coma, astigmatism, and spherical aberration. Moreover holographic aberration correction enables us to compensate inherent shortcomings in the optical train, thereby adaptively improving its performance. We also demonstrate the effects of geometric aberrations on the intensity profiles of optical vortices, whose readily measured deformations suggest a method for rapidly estimating and correcting geometric aberrations in holographic trapping systems

  14. Kidney Scanning with Hippuran: A Necessary Complement for Correct Interpretation of Renography in the Transplanted Kidney

    Energy Technology Data Exchange (ETDEWEB)

    Lubin, E.; Lewitus, Z.; Rosenfeld, J.; Levi, M. [Beilinson Medical Centre, University of Tel Aviv School of Medicine (Israel)

    1969-05-15

    Every impairment of the kidneys' blood supply, and the production or excretion of urine, is reflected by abnormal renograms that are not specific enough in the information they provide. The subsequent performance of renal scans with Hippuran {sup 131}I adds information to the topographical distribution of the Hippuran {sup 131}I in the renal parenchyma, and to the dynamics of its transport through the urinary system. The information thus obtained is valuable in itself and is necessary for the correct interpretation of renography. We have found this specially useful in the follow-up of the transplanted kidneys. In cases of anuria following renal transplantation, the renogram is useful for indicating that renal circulation is present in the transplanted kidney but is inadequate as a method to differentiate between other renal and post-renal causes of anuria. The anuric transplanted kidney should be scanned thirty minutes after the injection of Hippuran {sup 131}I. Patterns of complementary results of renograms and renal scannings are presented that correspond to prerenal, renal and postrenal causes of anuria, with all the important therapeutic implications this differential diagnosis has. (author)

  15. Restoring defect structures in 3C-SiC/Si (001) from spherical aberration-corrected high-resolution transmission electron microscope images by means of deconvolution processing.

    Science.gov (United States)

    Wen, C; Wan, W; Li, F H; Tang, D

    2015-04-01

    The [110] cross-sectional samples of 3C-SiC/Si (001) were observed with a spherical aberration-corrected 300 kV high-resolution transmission electron microscope. Two images taken not close to the Scherzer focus condition and not representing the projected structures intuitively were utilized for performing the deconvolution. The principle and procedure of image deconvolution and atomic sort recognition are summarized. The defect structure restoration together with the recognition of Si and C atoms from the experimental images has been illustrated. The structure maps of an intrinsic stacking fault in the area of SiC, and of Lomer and 60° shuffle dislocations at the interface have been obtained at atomic level. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. ac driving amplitude dependent systematic error in scanning Kelvin probe microscope measurements: Detection and correction

    International Nuclear Information System (INIS)

    Wu Yan; Shannon, Mark A.

    2006-01-01

    The dependence of the contact potential difference (CPD) reading on the ac driving amplitude in scanning Kelvin probe microscope (SKPM) hinders researchers from quantifying true material properties. We show theoretically and demonstrate experimentally that an ac driving amplitude dependence in the SKPM measurement can come from a systematic error, and it is common for all tip sample systems as long as there is a nonzero tracking error in the feedback control loop of the instrument. We further propose a methodology to detect and to correct the ac driving amplitude dependent systematic error in SKPM measurements. The true contact potential difference can be found by applying a linear regression to the measured CPD versus one over ac driving amplitude data. Two scenarios are studied: (a) when the surface being scanned by SKPM is not semiconducting and there is an ac driving amplitude dependent systematic error; (b) when a semiconductor surface is probed and asymmetric band bending occurs when the systematic error is present. Experiments are conducted using a commercial SKPM and CPD measurement results of two systems: platinum-iridium/gap/gold and platinum-iridium/gap/thermal oxide/silicon are discussed

  17. Geometrical correction of the e-beam proximity effect for raster scan systems

    Science.gov (United States)

    Belic, Nikola; Eisenmann, Hans; Hartmann, Hans; Waas, Thomas

    1999-06-01

    Increasing demands on pattern fidelity and CD accuracy in e- beam lithography require a correction of the e-beam proximity effect. The new needs are mainly coming from OPC at mask level and x-ray lithography. The e-beam proximity limits the achievable resolution and affects neighboring structures causing under- or over-exposion depending on the local pattern densities and process settings. Methods to compensate for this unequilibrated does distribution usually use a dose modulation or multiple passes. In general raster scan systems are not able to apply variable doses in order to compensate for the proximity effect. For system of this kind a geometrical modulation of the original pattern offers a solution for compensation of line edge deviations due to the proximity effect. In this paper a new method for the fast correction of the e-beam proximity effect via geometrical pattern optimization is described. The method consists of two steps. In a first step the pattern dependent dose distribution caused by back scattering is calculated by convolution of the pattern with the long range part of the proximity function. The restriction to the long range part result in a quadratic sped gain in computing time for the transformation. The influence of the short range part coming from forward scattering is not pattern dependent and can therefore be determined separately in a second step. The second calculation yields the dose curve at the border of a written structure. The finite gradient of this curve leads to an edge displacement depending on the amount of underground dosage at the observed position which was previously determined in the pattern dependent step. This unintended edge displacement is corrected by splitting the line into segments and shifting them by multiples of the writers address grid to the opposite direction.

  18. Investigating the effect and photon scattering correction in isotopic scanning with gamma and SPECT

    International Nuclear Information System (INIS)

    Movafeghi, Amir

    1997-01-01

    Nowdays medical imaging systems has been become a very important tool in medicine, both in diagnosis and treatment. With the fast improvement in the computer sciences in the last three decades, three dimensional imaging systems or topographic systems has been developed for the daily applications. Among the different methods, for now X-ray Computerized tomography scanning, Magnetic Resonance Imaging, Single Photon Emission Computerized Tomography and Positron Emission tomography have been found many clinical application. SPECT and PET imaging systems are working with the use of emitting photons from special radioisotopes. In these two systems, image is reconstructed from a distribution of radioisotope in the human body's organs. In SPECT accuracy of data quantification for image reconstruction has influenced from photon attenuation, photon scattering, statistical noises and variation in detector response due to distance. Except scattering other three factors could be modeled and compensated with relatively simple models. Photon scattering is a complex process and usually semiemperical methods is used for its modeling. The effect of scattering photons on images was considered. This survey was done in both lab and clinical cases. Radioisotopes were 192 Ir and 99m Tc. 192 Ir is a solid source with the half-life of 73 days and is used at industrial radiography application. At the beginning, models and methods, were established by the help of 192 Ir. Then at the final stage, they were developed to use for 99m Tc. There are different methods for the error correction of scattered photons. A method from the 'window subtraction' group has been developed for lab cases. Generally, in this method with the use of adjacent window of the photopeak window, scattered photons are subtracted from the original count. A Monte Carlo simulation is used for better evaluation of results. In the clinical section , a dual head SPECT system was (ADAC system of Shariati hospital at Tehran). The

  19. Stellar aberration correction and thermoelastic compensation of Swarm μASC attitude observations: A comment to the Express Letter “Mysterious misalignments between geomagnetic and stellar reference frames seen in CHAMP and Swarm satellite measurements”, by Stefan Maus

    DEFF Research Database (Denmark)

    Herceg, M.; Jørgensen, P. S.; Jørgensen, J. L.

    2017-01-01

    . However, comparison of the Inter Boresight Angle shows a relative attitude variation between the μASC Camera Head Units. These misalignments between Camera Head Units and a geomagnetic reference frame cannot be explained by incorrect aberration correction (as theorized by Maus). Herceg et al. found them...... and clean from any variation caused by thermoelastic effects....

  20. Wide aperture multipole magnets of the kinematic separator COMBAS. Correcting pair of multipole magnets M3M4 (M5M6) with compensation for higher order aberrations

    International Nuclear Information System (INIS)

    Artyukh, A.G.; Gridnev, G.F.; Teterev, Yu.G.

    1999-01-01

    The high-resolving large aperture separator COMBAS has been created and commissioned. The magneto-optical structure of the separator is based on the strong focusing principle. The separator consists of eight wide aperture multipole magnets M1-M8. The magnets M1, M2, M7, M8 forming the 1 st order optics together with some higher order optical corrections and M3-M6 being dedicated to higher order corrections of the chromatic and spherical aberrations at the intermediate and exit foci of the separator. The multipole correctors M3-M6 contain the dipolar, sextupole and octupole components in their magnetic field distributions. It was the use of the rectangular dipoles M3-M6 as carriers of sextupole and octupole field components that let achieve high values of the separator angular and momentum acceptances. Measurements of the magnetic field distributions in the median planes of the pairs of magnets M3M6 (M4M5) have been performed. These measurements allowed one to analyze the magnets manufacturing quality. Based on the analysis, shimming of pole pieces of the pair of magnets M3M6 have been done. Pole surface correcting coils for the magnets M4M5 have been foreseen to compensate for small deviations (within a few percents) of the 2 nd and 3 rd order field components from the design values, which are probable due to manufacturing errors in all the magnets M1-M8. The measured magnetic field distributions are supposed to be used for particle trajectory simulations throughout the entire separator

  1. Chromosomal aberration

    International Nuclear Information System (INIS)

    Ishii, Yutaka

    1988-01-01

    Chromosomal aberrations are classified into two types, chromosome-type and chromatid-type. Chromosom-type aberrations include terminal deletion, dicentric, ring and interstitial deletion, and chromatid-type aberrations include achromatic lesion, chromatid deletion, isochromatid deletion and chromatid exchange. Clastogens which induce chromosomal aberration are divided into ''S-dependent'' agents and ''S-independent''. It might mean whether they can induce double strand breaks independent of the S phase or not. Double strand breaks may be the ultimate lesions to induce chromosomal aberrations. Caffeine added even in the G 2 phase appeared to modify the frequency of chromatid aberrations induced by X-rays and mitomycin C. Those might suggest that the G 2 phase involves in the chromatid aberration formation. The double strand breaks might be repaired by ''G 2 repair system'', the error of which might yield breakage types of chromatid aberrations and the by-pass of which might yield chromatid exchanges. Chromosome-type aberrations might be formed in the G 1 phase. (author)

  2. The effect, identification and correction of misalignment between PET transmission and emission scans on brain PET imaging

    International Nuclear Information System (INIS)

    Zhang Xiangsong; He Zuoxiang; Tang Anwu; Qiao Suixian

    2004-01-01

    Objectives: To study the effect of misalignment between PET transmission and emission scans of brain on brain PET imaging, and the Methods to identify and correct it. Methods: 18F-FDG PET imaging was performed on 8 volunteers. The emission images were reconstructed with attenuation correction after some translations and rotations in the x-axis and transverse plane were given, 1 mm and 1 degree each step, respectively. The 3-D volume fusion of PET emission and transmission scans was used to identify the suspected misalignment on 10 18F-FDG PET brain imaging. Three Methods were used to correct the misalignment. First, to quantitate the amount of the misalignment by 3-D volume registration of PET emission and transmission scans, the emission images were reconstructed with corrected translations and rotations in x-direction and transverse plane. Second, the emission images were reconstructed with mathematic calculation of brain attenuation. Third, 18F-FDG PET brain imaging was redone with careful application of laser alignment. Results: The translations greater than 3 mm in x-direction and the rotations greater than 8 degrees in transverse plane could lead to visible artifacts, which were presented with decreasing radioactivity uptake in the cortex of half cerebrum and in the frontal cortex at the side in the translating or rotating direction, respectively. The 3-D volume fusion of PET emission and transmission scans could identify and quantitate the amount of misalignment between PET emission and transmission scans of brain. The PET emission images reconstructed with corrected misalignment and mathematic calculation of brain attenuation were consistent with redone PET brain imaging. Conclusions: The misalignment between PET transmission and emission scans of brain can lead to visible artifacts. The 3-D volume fusion of PET emission and transmission scans can identify and quantitate the amount of the misalignment. The visible artifacts caused by the misalignment can be

  3. [Impact of an Aspherical Aberration Correcting Monofocal Intraocular Lens on Patient Satisfaction for Daily Life Activities: The Heidelberg Daily Task Evaluation (DATE) Questionnaire].

    Science.gov (United States)

    Kretz, F T A; Son, H; Liebing, S; Tandogan, T; Auffarth, G U

    2015-08-01

    A clinical evaluation of the functional results and its impact on daily activities of an aspherical, aberration correcting intraocular lens (IOL) was undertaken. Twenty-one patients aged from 50 to 83 years underwent cataract surgery with implantation of the aspheric IOL (Tecnis ZCB00, Abbott Medical Optics). They were evaluated 2 to 4 months after surgery for their subjective satisfaction of vision quality and its impact on performance of daily activities as well as functional results and refractive outcome. Patients were asked to fill out a questionnaire - the Heidelberg DATE (DAily Tasks Evaluation) questionnaire. Significant changes from pre- to postoperative results were found in refraction (p ≤ 0.03), with a mean prediction error of + 0.21 ± 0.43 D. UDVA and CDVA improved significantly (p < 0.01), with a postoperative CDVA of 0.0 logMAR or better in 97.1 % of eyes. All patients would recommend the procedure to a relative or a friend and 93.8 % of patients reported to be satisfied with the outcome. The implantation of the aspheric IOL Tecnis ZCB00 after cataract surgery allows the restoration of visual function, providing an optimised optical quality and a high level of patient satisfaction. Georg Thieme Verlag KG Stuttgart · New York.

  4. Fast Focal Point Correction in Prism-Coupled Total Internal Reflection Scanning Imager Using an Electronically Tunable Lens

    Directory of Open Access Journals (Sweden)

    Chenggang Zhu

    2018-02-01

    Full Text Available Total internal reflection (TIR is useful for interrogating physical and chemical processes that occur at the interface between two transparent media. Yet prism-coupled TIR imaging microscopes suffer from limited sensing areas due to the fact that the interface (the object plane is not perpendicular to the optical axis of the microscope. In this paper, we show that an electrically tunable lens can be used to rapidly and reproducibly correct the focal length of an oblique-incidence scanning microscope (OI-RD in a prism-coupled TIR geometry. We demonstrate the performance of such a correction by acquiring an image of a protein microarray over a scan area of 4 cm2 with an effective resolution of less than 20 microns. The electronic focal length tuning eliminates the mechanical movement of the illumination lens in the scanning microscope and in turn the noise and background drift associated with the motion.

  5. Correction

    DEFF Research Database (Denmark)

    Pinkevych, Mykola; Cromer, Deborah; Tolstrup, Martin

    2016-01-01

    [This corrects the article DOI: 10.1371/journal.ppat.1005000.][This corrects the article DOI: 10.1371/journal.ppat.1005740.][This corrects the article DOI: 10.1371/journal.ppat.1005679.].......[This corrects the article DOI: 10.1371/journal.ppat.1005000.][This corrects the article DOI: 10.1371/journal.ppat.1005740.][This corrects the article DOI: 10.1371/journal.ppat.1005679.]....

  6. Camera processing with chromatic aberration.

    Science.gov (United States)

    Korneliussen, Jan Tore; Hirakawa, Keigo

    2014-10-01

    Since the refractive index of materials commonly used for lens depends on the wavelengths of light, practical camera optics fail to converge light to a single point on an image plane. Known as chromatic aberration, this phenomenon distorts image details by introducing magnification error, defocus blur, and color fringes. Though achromatic and apochromatic lens designs reduce chromatic aberration to a degree, they are complex and expensive and they do not offer a perfect correction. In this paper, we propose a new postcapture processing scheme designed to overcome these problems computationally. Specifically, the proposed solution is comprised of chromatic aberration-tolerant demosaicking algorithm and post-demosaicking chromatic aberration correction. Experiments with simulated and real sensor data verify that the chromatic aberration is effectively corrected.

  7. Measuring chromatic aberrations in imaging systems using plasmonic nanoparticles.

    Science.gov (United States)

    Gennaro, Sylvain D; Roschuk, Tyler R; Maier, Stefan A; Oulton, Rupert F

    2016-04-01

    We demonstrate a method to measure chromatic aberrations of microscope objectives with metallic nanoparticles using white light. Extinction spectra are recorded while scanning a single nanoparticle through a lens's focal plane. We show a direct correlation between the focal wavelength and the longitudinal chromatic focal shift through our analysis of the variations between the scanned extinction spectra at each scan position and the peak extinction over the entire scan. The method has been tested on achromat and apochromat objectives using aluminum disks varying in size from 260-520 nm. Our method is straightforward, robust, low cost, and broadband with a sensitivity suitable for assessing longitudinal chromatic aberrations in high-numerical-aperture apochromatic corrected lenses.

  8. Aberration compensation of an ultrasound imaging instrument with a reduced number of channels.

    Science.gov (United States)

    Jiang, Wei; Astheimer, Jeffrey P; Waag, Robert C

    2012-10-01

    Focusing and imaging qualities of an ultrasound imaging system that uses aberration correction were experimentally investigated as functions of the number of parallel channels. Front-end electronics that consolidate signals from multiple physical elements can be used to lower hardware and computational costs by reducing the number of parallel channels. However, the signals from sparse arrays of synthetic elements yield poorer aberration estimates. In this study, aberration estimates derived from synthetic arrays of varying element sizes are evaluated by comparing compensated receive focuses, compensated transmit focuses, and compensated b-scan images of a point target and a cyst phantom. An array of 80 x 80 physical elements with a pitch of 0.6 x 0.6 mm was used for all of the experiments and the aberration was produced by a phantom selected to mimic propagation through abdominal wall. The results show that aberration correction derived from synthetic arrays with pitches that have a diagonal length smaller than 70% of the correlation length of the aberration yield focuses and images of approximately the same quality. This connection between correlation length of the aberration and synthetic element size provides a guideline for determining the number of parallel channels that are required when designing imaging systems that employ aberration correction.

  9. Morphobiochemical diagnosis of acute trabecular microfractures using gamma correction Tc-99m HDP pinhole bone scan with histopathological verification.

    Science.gov (United States)

    Bahk, Yong-Whee; Hwang, Seok-Ha; Lee, U-Young; Chung, Yong-An; Jung, Joo-Young; Jeong, Hyeonseok S

    2017-11-01

    We prospectively performed gamma correction pinhole bone scan (GCPBS) and histopathologic verification study to make simultaneous morphobiochemical diagnosis of trabecular microfractures (TMF) occurred in the femoral head as a part of femoral neck fracture.Materials consisted of surgical specimens of the femoral head in 6 consecutive patients. The specimens were imaged using Tc-99m hydroxymethylene diphosphonate (HDP) pinhole scan and processed by the gamma correction. After cleansing with 10% formalin solution, injured specimen surface was observed using a surgical microscope to record TMF. Morphological findings shown in the photograph, naive pinhole bone scan, GCPBS, and hematoxylin-eosin (H&E) stain of the specimen were reciprocally correlated for histological verification and the usefulness of suppression and enhancement of Tc-99m HDP uptake was biochemically investigated in TMF and edema and hemorrhage using gamma correction.On the one hand, GCPBS was able to depict the calcifying calluses in TMF with enhanced Tc-99m HDP uptake. They were pinpointed, speckled, round, ovoid, rod-like, geographic, and crushed in shape. The smallest callus measured was 0.23 mm in this series. On the other hand, GCPBS biochemically was able to discern the calluses with enhanced high Tc-99m HDP uptake from the normal and edema dipped and hemorrhage irritated trabeculae with washed out uptake.Morphobiochemically, GCPBS can clearly depict microfractures in the femoral head produced by femoral neck fracture. It discerns the microcalluses with enhanced Tc-99m HDP uptake from the intact and edema dipped and hemorrhage irritated trabeculae with suppressed washed out Tc-99m HDP uptake. Both conventional pinhole bone scan and gamma correction are useful imaging means to specifically diagnose the microcalluses naturally formed in TMF.

  10. SU-E-T-464: On the Equivalence of the Quality Correction Factor for Pencil Beam Scanning Proton Therapy

    International Nuclear Information System (INIS)

    Sorriaux, J; Paganetti, H; Testa, M; Giantsoudi, D; Schuemann, J; Bertrand, D; Orban de Xivry, J.; Lee, J; Palmans, H; Vynckier, S; Sterpin, E

    2014-01-01

    Purpose: In current practice, most proton therapy centers apply IAEA TRS-398 reference dosimetry protocol. Quality correction factors (kQ) take into account in the dose determination process the differences in beam qualities used for calibration unit and for treatment unit. These quality correction factors are valid for specific reference conditions. TRS-398 reference conditions should be achievable in both scattered proton beams (i.e. DS) and scanned proton beams (i.e. PBS). However, it is not a priori clear if TRS-398 kQ data, which are based on Monte Carlo (MC) calculations in scattered beams, can be used for scanned beams. Using TOPAS-Geant4 MC simulations, the study aims to determine whether broad beam quality correction factors calculated in TRS-398 can be directly applied to PBS delivery modality. Methods: As reference conditions, we consider a 10×10×10 cm 3 homogeneous dose distribution delivered by PBS system in a water phantom (32/10 cm range/modulation) and an air cavity placed at the center of the spread-out-Bragg-peak. In order to isolate beam differences, a hypothetical broad beam is simulated. This hypothetical beam reproduces exactly the same range modulation, and uses the same energy layers than the PBS field. Ion chamber responses are computed for the PBS and hypothetical beams and then compared. Results: For an air cavity of 2×2×0.2 cm 3 , the ratio of ion chamber responses for the PBS and hypothetical beam qualities is 0.9991 ± 0.0016. Conclusion: Quality correction factors are insensitive to the delivery pattern of the beam (broad beam or PBS), as long as similar dose distributions are achieved. This investigation, for an air cavity, suggests that broad beam quality correction factors published in TRS-398 can be applied for scanned beams. J. Sorriaux is financially supported by a public-private partnership involving the company Ion Beam Applications (IBA)

  11. SU-F-BRD-15: Quality Correction Factors in Scanned Or Broad Proton Therapy Beams Are Indistinguishable

    Energy Technology Data Exchange (ETDEWEB)

    Sorriaux, J; Lee, J [Molecular Imaging Radiotherapy & Oncology, Universite Catholique de Louvain, Brussels (Belgium); ICTEAM Institute, Universite catholique de Louvain, Louvain-la-Neuve (Belgium); Testa, M; Paganetti, H [Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, Massachusetts (United States); Bertrand, D; Orban de Xivry, J [Ion Beam Applications, Louvain-la-neuve, Brabant Wallon (Belgium); Palmans, H [EBG MedAustron GmbH, Wiener Neustadt (Austria); National Physical Laboratory, Teddington (United Kingdom); Vynckier, S [Cliniques Universitaires Saint-Luc, Brussels (Belgium); Sterpin, E [Molecular Imaging Radiotherapy & Oncology, Universite Catholique de Louvain, Brussels (Belgium)

    2015-06-15

    Purpose: The IAEA TRS-398 code of practice details the reference conditions for reference dosimetry of proton beams using ionization chambers and the required beam quality correction factors (kQ). Pencil beam scanning (PBS) requires multiple spots to reproduce the reference conditions. The objective is to demonstrate, using Monte Carlo (MC) calculations, that kQ factors for broad beams can be used for scanned beams under the same reference conditions with no significant additional uncertainty. We consider hereafter the general Alfonso formalism (Alfonso et al, 2008) for non-standard beam. Methods: To approach the reference conditions and the associated dose distributions, PBS must combine many pencil beams with range modulation and shaping techniques different than those used in passive systems (broad beams). This might lead to a different energy spectrum at the measurement point. In order to evaluate the impact of these differences on kQ factors, ion chamber responses are computed with MC (Geant4 9.6) in a dedicated scanned pencil beam (Q-pcsr) producing a 10×10cm2 composite field with a flat dose distribution from 10 to 16 cm depth. Ion chamber responses are also computed by MC in a broad beam with quality Q-ds (double scattering). The dose distribution of Q -pcsr matches the dose distribution of Q-ds. k-(Q-pcsr,Q-ds) is computed for a 2×2×0.2cm{sup 3} idealized air cavity and a realistic plane-parallel ion chamber (IC). Results: Under reference conditions, quality correction factors for a scanned composite field versus a broad beam are the same for air cavity dose response, k-(Q-pcsr,Q-ds) =1.001±0.001 and for a Roos IC, k-(Q-pcsr,Q-ds) =0.999±0.005. Conclusion: Quality correction factors for ion chamber response in scanned and broad proton therapy beams are identical under reference conditions within the calculation uncertainties. The results indicate that quality correction factors published in IAEA TRS-398 can be used for scanned beams in the SOBP of a

  12. SU-F-BRD-15: Quality Correction Factors in Scanned Or Broad Proton Therapy Beams Are Indistinguishable

    International Nuclear Information System (INIS)

    Sorriaux, J; Lee, J; Testa, M; Paganetti, H; Bertrand, D; Orban de Xivry, J; Palmans, H; Vynckier, S; Sterpin, E

    2015-01-01

    Purpose: The IAEA TRS-398 code of practice details the reference conditions for reference dosimetry of proton beams using ionization chambers and the required beam quality correction factors (kQ). Pencil beam scanning (PBS) requires multiple spots to reproduce the reference conditions. The objective is to demonstrate, using Monte Carlo (MC) calculations, that kQ factors for broad beams can be used for scanned beams under the same reference conditions with no significant additional uncertainty. We consider hereafter the general Alfonso formalism (Alfonso et al, 2008) for non-standard beam. Methods: To approach the reference conditions and the associated dose distributions, PBS must combine many pencil beams with range modulation and shaping techniques different than those used in passive systems (broad beams). This might lead to a different energy spectrum at the measurement point. In order to evaluate the impact of these differences on kQ factors, ion chamber responses are computed with MC (Geant4 9.6) in a dedicated scanned pencil beam (Q-pcsr) producing a 10×10cm2 composite field with a flat dose distribution from 10 to 16 cm depth. Ion chamber responses are also computed by MC in a broad beam with quality Q-ds (double scattering). The dose distribution of Q -pcsr matches the dose distribution of Q-ds. k-(Q-pcsr,Q-ds) is computed for a 2×2×0.2cm 3 idealized air cavity and a realistic plane-parallel ion chamber (IC). Results: Under reference conditions, quality correction factors for a scanned composite field versus a broad beam are the same for air cavity dose response, k-(Q-pcsr,Q-ds) =1.001±0.001 and for a Roos IC, k-(Q-pcsr,Q-ds) =0.999±0.005. Conclusion: Quality correction factors for ion chamber response in scanned and broad proton therapy beams are identical under reference conditions within the calculation uncertainties. The results indicate that quality correction factors published in IAEA TRS-398 can be used for scanned beams in the SOBP of a high

  13. The correction of vibration in frequency scanning interferometry based absolute distance measurement system for dynamic measurements

    Science.gov (United States)

    Lu, Cheng; Liu, Guodong; Liu, Bingguo; Chen, Fengdong; Zhuang, Zhitao; Xu, Xinke; Gan, Yu

    2015-10-01

    Absolute distance measurement systems are of significant interest in the field of metrology, which could improve the manufacturing efficiency and accuracy of large assemblies in fields such as aircraft construction, automotive engineering, and the production of modern windmill blades. Frequency scanning interferometry demonstrates noticeable advantages as an absolute distance measurement system which has a high precision and doesn't depend on a cooperative target. In this paper , the influence of inevitable vibration in the frequency scanning interferometry based absolute distance measurement system is analyzed. The distance spectrum is broadened as the existence of Doppler effect caused by vibration, which will bring in a measurement error more than 103 times bigger than the changes of optical path difference. In order to decrease the influence of vibration, the changes of the optical path difference are monitored by a frequency stabilized laser, which runs parallel to the frequency scanning interferometry. The experiment has verified the effectiveness of this method.

  14. The problem in 180 deg data sampling and radioactivity decay correction in gated cardiac blood pool scanning using SPECT

    International Nuclear Information System (INIS)

    Ohtake, Tohru; Watanabe, Toshiaki; Nishikawa, Junichi

    1986-01-01

    In cardiac blood pool scanning using SPECT, half 180 deg data collection (HD) vs. full 360 deg data collection (FD) and Tc-99m decay are problems in quantifying the ejection count (EC) (end-diastolic count - end-systolic count) of both ventricles and the ratio of the ejection count of the right and left ventricles (RVEC/LVEC). We studied the change produced by altering the starting position of data sampling in HD scans. In our results of phantom and 4 clinical cases, when the cardiac axis deviation was not large and there was not remarkable cardiac enlargement, the change in LVEC, RVEC and RVEC/LVEC was small (1 - 4 %) within 12 degree change of the starting position, and the difference between the results of HD scan with a good starting position (the average of LV peak and RV peak) and FD scan was not large (less than 7 %). Because of this, we think HD scan can be used in those cases. But when the cardiac axis deviation was large or there was remarkable cardiac enlargement, the change of LVEC, RVEC and RVEC/LVEC was large (more than 10 %) even within 12 degree change of the starting position. So we think FD scan would be better in those cases. In our results of 6 patients, the half-life of Tc-99m labeled albumin in blood varied from 2 to 4 hr (3.03 ± 0.59 hr, mean ± s.d.). Using a program for radioactivity (RA) decay correction, we studied the change in LVEC, RVEC and LVEC/RVEC in 11 cases. When RA decay correction was performed using a halflife of 3.0 hr, LVEC increased 7.5 %, RVEC increased 8.7 % and RVEC/LVEC increased 0.9 % on the average in HD scans of 8 cases (LPO to RAO, 32 views, 60 beat/1 view). We think RA decay correction would not be needed in quantifying RVEC/LVEC in most cases because the change of RVEC/LVEC was very small. (author)

  15. Real-space post-processing correction of thermal drift and piezoelectric actuator nonlinearities in scanning tunneling microscope images

    Science.gov (United States)

    Yothers, Mitchell P.; Browder, Aaron E.; Bumm, Lloyd A.

    2017-01-01

    We have developed a real-space method to correct distortion due to thermal drift and piezoelectric actuator nonlinearities on scanning tunneling microscope images using Matlab. The method uses the known structures typically present in high-resolution atomic and molecularly resolved images as an internal standard. Each image feature (atom or molecule) is first identified in the image. The locations of each feature's nearest neighbors are used to measure the local distortion at that location. The local distortion map across the image is simultaneously fit to our distortion model, which includes thermal drift in addition to piezoelectric actuator hysteresis and creep. The image coordinates of the features and image pixels are corrected using an inverse transform from the distortion model. We call this technique the thermal-drift, hysteresis, and creep transform. Performing the correction in real space allows defects, domain boundaries, and step edges to be excluded with a spatial mask. Additional real-space image analyses are now possible with these corrected images. Using graphite(0001) as a model system, we show lattice fitting to the corrected image, averaged unit cell images, and symmetry-averaged unit cell images. Statistical analysis of the distribution of the image features around their best-fit lattice sites measures the aggregate noise in the image, which can be expressed as feature confidence ellipsoids.

  16. Real-space post-processing correction of thermal drift and piezoelectric actuator nonlinearities in scanning tunneling microscope images.

    Science.gov (United States)

    Yothers, Mitchell P; Browder, Aaron E; Bumm, Lloyd A

    2017-01-01

    We have developed a real-space method to correct distortion due to thermal drift and piezoelectric actuator nonlinearities on scanning tunneling microscope images using Matlab. The method uses the known structures typically present in high-resolution atomic and molecularly resolved images as an internal standard. Each image feature (atom or molecule) is first identified in the image. The locations of each feature's nearest neighbors are used to measure the local distortion at that location. The local distortion map across the image is simultaneously fit to our distortion model, which includes thermal drift in addition to piezoelectric actuator hysteresis and creep. The image coordinates of the features and image pixels are corrected using an inverse transform from the distortion model. We call this technique the thermal-drift, hysteresis, and creep transform. Performing the correction in real space allows defects, domain boundaries, and step edges to be excluded with a spatial mask. Additional real-space image analyses are now possible with these corrected images. Using graphite(0001) as a model system, we show lattice fitting to the corrected image, averaged unit cell images, and symmetry-averaged unit cell images. Statistical analysis of the distribution of the image features around their best-fit lattice sites measures the aggregate noise in the image, which can be expressed as feature confidence ellipsoids.

  17. Movement correction of the kidney in dynamic MRI scans using FFT phase difference movement detection

    NARCIS (Netherlands)

    Giele, ELW; de Priester, JA; Blom, JA; den Boer, JA; van Engelshoven, JMA; Hasman, A; Geerlings, M

    2001-01-01

    To measure cortical and medullary MR renograms, regions of interest (ROIs) are placed on the kidney in images acquired using dynamic MRI. Since native kidneys move with breathing, and breath-holding techniques are not feasible, movement correction is necessary. In this contribution we compare three

  18. Atmospheric correction for JPSS-2 VIIRS response versus scan angle measurements

    Science.gov (United States)

    McIntire, Jeffrey; Moeller, Chris; Oudrari, Hassan; Xiong, Xiaoxiong

    2017-09-01

    The Joint Polar Satellite System 2 (JPSS-2) Visible Infrared Imaging Radiometer Suite (VIIRS) includes one spectral band centered in a strong atmospheric absorption region. As much of the pre-launch calibration is performed under laboratory ambient conditions, accurately accounting for the absorption, and thereby ensuring the transfer of the sensor calibration to on-orbit operations, is necessary to generate science quality data products. This work is focused on the response versus scan angle (RVS) measurements, which characterize the relative scan angle dependent reflectance of the JPSS-2 VIIRS instrument optics. The spectral band of interest, centered around 1378 nm, is within a spectral region strongly effected by water vapor absorption. The methodology used to model the absolute humidity and the atmospheric transmittance under the laboratory conditions is detailed. The application of this transmittance to the RVS determination is then described including an uncertainty estimate; a comparison to the pre-launch measurements from earlier sensor builds is also performed.

  19. Precision controlled atomic resolution scanning transmission electron microscopy using spiral scan pathways

    Science.gov (United States)

    Sang, Xiahan; Lupini, Andrew R.; Ding, Jilai; Kalinin, Sergei V.; Jesse, Stephen; Unocic, Raymond R.

    2017-03-01

    Atomic-resolution imaging in an aberration-corrected scanning transmission electron microscope (STEM) can enable direct correlation between atomic structure and materials functionality. The fast and precise control of the STEM probe is, however, challenging because the true beam location deviates from the assigned location depending on the properties of the deflectors. To reduce these deviations, i.e. image distortions, we use spiral scanning paths, allowing precise control of a sub-Å sized electron probe within an aberration-corrected STEM. Although spiral scanning avoids the sudden changes in the beam location (fly-back distortion) present in conventional raster scans, it is not distortion-free. “Archimedean” spirals, with a constant angular frequency within each scan, are used to determine the characteristic response at different frequencies. We then show that such characteristic functions can be used to correct image distortions present in more complicated constant linear velocity spirals, where the frequency varies within each scan. Through the combined application of constant linear velocity scanning and beam path corrections, spiral scan images are shown to exhibit less scan distortion than conventional raster scan images. The methodology presented here will be useful for in situ STEM imaging at higher temporal resolution and for imaging beam sensitive materials.

  20. List-Mode PET Motion Correction Using Markerless Head Tracking: Proof-of-Concept With Scans of Human Subject

    DEFF Research Database (Denmark)

    Olesen, Oline Vinter; Sullivan, Jenna M.; Mulnix, Tim

    2013-01-01

    A custom designed markerless tracking system was demonstrated to be applicable for positron emission tomography (PET) brain imaging. Precise head motion registration is crucial for accurate motion correction (MC) in PET imaging. State-of-the-art tracking systems applied with PET brain imaging rely...... on markers attached to the patient's head. The marker attachment is the main weakness of these systems. A healthy volunteer participating in a cigarette smoking study to image dopamine release was scanned twice for 2 h with $^{11}{\\rm C}$-racolopride on the high resolution research tomograph (HRRT) PET...... in contrast recovery of small structures....

  1. Correction of phase-shifting error in wavelength scanning digital holographic microscopy

    Science.gov (United States)

    Zhang, Xiaolei; Wang, Jie; Zhang, Xiangchao; Xu, Min; Zhang, Hao; Jiang, Xiangqian

    2018-05-01

    Digital holographic microscopy is a promising method for measuring complex micro-structures with high slopes. A quasi-common path interferometric apparatus is adopted to overcome environmental disturbances, and an acousto-optic tunable filter is used to obtain multi-wavelength holograms. However, the phase shifting error caused by the acousto-optic tunable filter reduces the measurement accuracy and, in turn, the reconstructed topographies are erroneous. In this paper, an accurate reconstruction approach is proposed. It corrects the phase-shifting errors by minimizing the difference between the ideal interferograms and the recorded ones. The restriction on the step number and uniformity of the phase shifting is relaxed in the interferometry, and the measurement accuracy for complex surfaces can also be improved. The universality and superiority of the proposed method are demonstrated by practical experiments and comparison to other measurement methods.

  2. A model of distributed phase aberration for deblurring phase estimated from scattering.

    Science.gov (United States)

    Tillett, Jason C; Astheimer, Jeffrey P; Waag, Robert C

    2010-01-01

    Correction of aberration in ultrasound imaging uses the response of a point reflector or its equivalent to characterize the aberration. Because a point reflector is usually unavailable, its equivalent is obtained using statistical methods, such as processing reflections from multiple focal regions in a random medium. However, the validity of methods that use reflections from multiple points is limited to isoplanatic patches for which the aberration is essentially the same. In this study, aberration is modeled by an offset phase screen to relax the isoplanatic restriction. Methods are developed to determine the depth and phase of the screen and to use the model for compensation of aberration as the beam is steered. Use of the model to enhance the performance of the noted statistical estimation procedure is also described. Experimental results obtained with tissue-mimicking phantoms that implement different models and produce different amounts of aberration are presented to show the efficacy of these methods. The improvement in b-scan resolution realized with the model is illustrated. The results show that the isoplanatic patch assumption for estimation of aberration can be relaxed and that propagation-path characteristics and aberration estimation are closely related.

  3. A new method to detect and correct sample tilt in scanning transmission electron microscopy bright-field imaging

    Energy Technology Data Exchange (ETDEWEB)

    Brown, H.G. [School of Physics, University of Melbourne, Parkville, Victoria 3010 (Australia); Ishikawa, R.; Sánchez-Santolino, G. [Institute of Engineering Innovation, School of Engineering, University of Tokyo, Tokyo 113-8656 (Japan); Lugg, N.R., E-mail: shibata@sigma.t.u-tokyo.ac.jp [Institute of Engineering Innovation, School of Engineering, University of Tokyo, Tokyo 113-8656 (Japan); Ikuhara, Y. [Institute of Engineering Innovation, School of Engineering, University of Tokyo, Tokyo 113-8656 (Japan); Allen, L.J. [School of Physics, University of Melbourne, Parkville, Victoria 3010 (Australia); Shibata, N. [Institute of Engineering Innovation, School of Engineering, University of Tokyo, Tokyo 113-8656 (Japan)

    2017-02-15

    Important properties of functional materials, such as ferroelectric shifts and octahedral distortions, are associated with displacements of the positions of lighter atoms in the unit cell. Annular bright-field scanning transmission electron microscopy is a good experimental method for investigating such phenomena due to its ability to image light and heavy atoms simultaneously. To map atomic positions at the required accuracy precise angular alignment of the sample with the microscope optical axis is necessary, since misalignment (tilt) of the specimen contributes to errors in position measurements of lighter elements in annular bright-field imaging. In this paper it is shown that it is possible to detect tilt with the aid of images recorded using a central bright-field detector placed within the inner radius of the annular bright-field detector. For a probe focus near the middle of the specimen the central bright-field image becomes especially sensitive to tilt and we demonstrate experimentally that misalignment can be detected with a precision of less than a milliradian, as we also confirm in simulation. Coma in the probe, an aberration that can be misidentified as tilt of the specimen, is also investigated and it is shown how the effects of coma and tilt can be differentiated. The effects of tilt may be offset to a large extent by shifting the diffraction plane detector an amount equivalent to the specimen tilt and we provide an experimental proof of principle of this using a segmented detector system. - Highlights: • Octahedral distortions are associated with displacements of lighter atoms. • Annular bright-field imaging is sensitive to light and heavy atoms simultaneously. • Mistilt of the specimen leads to errors in position measurements of lighter elements. • It is possible to detect tilt using images taken by a central bright-field detector. • Tilt may be offset by shifting the diffraction plane detector by an equivalent amount.

  4. SU-E-I-60: The Correct Selection of Pitch and Rotation Time for Optimal CT Scanning : The Big Misconception

    International Nuclear Information System (INIS)

    Ranallo, F; Szczykutowicz, T

    2014-01-01

    Purpose: To provide correct guidance in the proper selection of pitch and rotation time for optimal CT imaging with multi-slice scanners. Methods: There exists a widespread misconception concerning the role of pitch in patient dose with modern multi-slice scanners, particularly with the use of mA modulation techniques. We investigated the relationship of pitch and rotation time to image quality, dose, and scan duration, with CT scanners from different manufacturers in a way that clarifies this misconception. This source of this misconception may concern the role of pitch in single slice CT scanners. Results: We found that the image noise and dose are generally independent of the selected effective mAs (mA*time/ pitch) with manual mA technique settings and are generally independent of the selected pitch and /or rotation time with automatic mA modulation techniques. However we did find that on certain scanners the use of a pitch just above 0.5 provided images of equal image noise at a lower dose compared to the use of a pitch just below 1.0. Conclusion: The misconception that the use of a lower pitch over-irradiates patients by wasting dose is clearly false. The use of a lower pitch provides images of equal or better image quality at the same patient dose, whether using manual mA or automatic mA modulation techniques. By decreasing the pitch and the rotation times by equal amounts, both helical and patient motion artifacts can be reduced without affecting the exam time. The use of lower helical pitch also allows better scanning of larger patients by allowing a greater scan effective mAs, if the exam time can be extended. The one caution with the use of low pitch is not related to patient dose, but to the length of the scan time if the rotation time is not set short enough. Partial Research funding from GE HealthCare

  5. Optical Aberrations and Wavefront

    Directory of Open Access Journals (Sweden)

    Nihat Polat

    2014-08-01

    Full Text Available The deviation of light to create normal retinal image in the optical system is called aberration. Aberrations are divided two subgroup: low-order aberrations (defocus: spherical and cylindrical refractive errors and high-order aberrations (coma, spherical, trefoil, tetrafoil, quadrifoil, pentafoil, secondary astigmatism. Aberrations increase with aging. Spherical aberrations are compensated by positive corneal and negative lenticular spherical aberrations in youth. Total aberrations are elevated by positive corneal and positive lenticular spherical aberrations in elderly. In this study, we aimed to analyze the basic terms regarding optic aberrations which have gained significance recently. (Turk J Ophthalmol 2014; 44: 306-11

  6. Correction

    CERN Multimedia

    2002-01-01

    Tile Calorimeter modules stored at CERN. The larger modules belong to the Barrel, whereas the smaller ones are for the two Extended Barrels. (The article was about the completion of the 64 modules for one of the latter.) The photo on the first page of the Bulletin n°26/2002, from 24 July 2002, illustrating the article «The ATLAS Tile Calorimeter gets into shape» was published with a wrong caption. We would like to apologise for this mistake and so publish it again with the correct caption.

  7. Quantitative atom column position analysis at the incommensurate interfaces of a (PbS)1.14NbS2 misfit layered compound with aberration-corrected HRTEM

    International Nuclear Information System (INIS)

    Garbrecht, M.; Spiecker, E.; Tillmann, K.; Jaeger, W.

    2011-01-01

    Aberration-corrected HRTEM is applied to explore the potential of NCSI contrast imaging to quantitatively analyse the complex atomic structure of misfit layered compounds and their incommensurate interfaces. Using the (PbS) 1.14 NbS 2 misfit layered compound as a model system it is shown that atom column position analyses at the incommensurate interfaces can be performed with precisions reaching a statistical accuracy of ±6 pm. The procedure adopted for these studies compares experimental images taken from compound regions free of defects and interface modulations with a structure model derived from XRD experiments and with multi-slice image simulations for the corresponding NCSI contrast conditions used. The high precision achievable in such experiments is confirmed by a detailed quantitative analysis of the atom column positions at the incommensurate interfaces, proving a tetragonal distortion of the monochalcogenide sublattice. -- Research Highlights: → Quantitative aberration-corrected HRTEM analysis of atomic column positions in (PbS) 1.14 NbS 2 misfit layered compound reveals tetragonal distortion of the PbS subsystem. → Detailed comparison of multi-slice simulations with the experimental NCSI contrast condition imaging results lead to a high precision (better than 10 pm) for determining the positions of atoms. → Precision in gaining information of local structure at atomic scale is demonstrated, which may not be accessible by means of X-ray and neutron diffraction analysis.

  8. Correction

    Directory of Open Access Journals (Sweden)

    2012-01-01

    Full Text Available Regarding Gorelik, G., & Shackelford, T.K. (2011. Human sexual conflict from molecules to culture. Evolutionary Psychology, 9, 564–587: The authors wish to correct an omission in citation to the existing literature. In the final paragraph on p. 570, we neglected to cite Burch and Gallup (2006 [Burch, R. L., & Gallup, G. G., Jr. (2006. The psychobiology of human semen. In S. M. Platek & T. K. Shackelford (Eds., Female infidelity and paternal uncertainty (pp. 141–172. New York: Cambridge University Press.]. Burch and Gallup (2006 reviewed the relevant literature on FSH and LH discussed in this paragraph, and should have been cited accordingly. In addition, Burch and Gallup (2006 should have been cited as the originators of the hypothesis regarding the role of FSH and LH in the semen of rapists. The authors apologize for this oversight.

  9. Correction

    CERN Multimedia

    2002-01-01

    The photo on the second page of the Bulletin n°48/2002, from 25 November 2002, illustrating the article «Spanish Visit to CERN» was published with a wrong caption. We would like to apologise for this mistake and so publish it again with the correct caption.   The Spanish delegation, accompanied by Spanish scientists at CERN, also visited the LHC superconducting magnet test hall (photo). From left to right: Felix Rodriguez Mateos of CERN LHC Division, Josep Piqué i Camps, Spanish Minister of Science and Technology, César Dopazo, Director-General of CIEMAT (Spanish Research Centre for Energy, Environment and Technology), Juan Antonio Rubio, ETT Division Leader at CERN, Manuel Aguilar-Benitez, Spanish Delegate to Council, Manuel Delfino, IT Division Leader at CERN, and Gonzalo León, Secretary-General of Scientific Policy to the Minister.

  10. Correction

    Directory of Open Access Journals (Sweden)

    2014-01-01

    Full Text Available Regarding Tagler, M. J., and Jeffers, H. M. (2013. Sex differences in attitudes toward partner infidelity. Evolutionary Psychology, 11, 821–832: The authors wish to correct values in the originally published manuscript. Specifically, incorrect 95% confidence intervals around the Cohen's d values were reported on page 826 of the manuscript where we reported the within-sex simple effects for the significant Participant Sex × Infidelity Type interaction (first paragraph, and for attitudes toward partner infidelity (second paragraph. Corrected values are presented in bold below. The authors would like to thank Dr. Bernard Beins at Ithaca College for bringing these errors to our attention. Men rated sexual infidelity significantly more distressing (M = 4.69, SD = 0.74 than they rated emotional infidelity (M = 4.32, SD = 0.92, F(1, 322 = 23.96, p < .001, d = 0.44, 95% CI [0.23, 0.65], but there was little difference between women's ratings of sexual (M = 4.80, SD = 0.48 and emotional infidelity (M = 4.76, SD = 0.57, F(1, 322 = 0.48, p = .29, d = 0.08, 95% CI [−0.10, 0.26]. As expected, men rated sexual infidelity (M = 1.44, SD = 0.70 more negatively than they rated emotional infidelity (M = 2.66, SD = 1.37, F(1, 322 = 120.00, p < .001, d = 1.12, 95% CI [0.85, 1.39]. Although women also rated sexual infidelity (M = 1.40, SD = 0.62 more negatively than they rated emotional infidelity (M = 2.09, SD = 1.10, this difference was not as large and thus in the evolutionary theory supportive direction, F(1, 322 = 72.03, p < .001, d = 0.77, 95% CI [0.60, 0.94].

  11. Mask-induced aberration in EUV lithography

    Science.gov (United States)

    Nakajima, Yumi; Sato, Takashi; Inanami, Ryoichi; Nakasugi, Tetsuro; Higashiki, Tatsuhiko

    2009-04-01

    We estimated aberrations using Zernike sensitivity analysis. We found the difference of the tolerated aberration with line direction for illumination. The tolerated aberration of perpendicular line for illumination is much smaller than that of parallel line. We consider this difference to be attributable to the mask 3D effect. We call it mask-induced aberration. In the case of the perpendicular line for illumination, there was a difference in CD between right line and left line without aberration. In this report, we discuss the possibility of pattern formation in NA 0.25 generation EUV lithography tool. In perpendicular pattern for EUV light, the dominant part of aberration is mask-induced aberration. In EUV lithography, pattern correction based on the mask topography effect will be more important.

  12. Novel use of gamma correction for precise {sup 99m}Tc-HDP pinhole bone scan diagnosis and classification of knee occult fractures

    Energy Technology Data Exchange (ETDEWEB)

    Bahk, Yong-Whee [Sung Ae General Hospital, Department of Nuclear Medicine, Seoul (Korea); Jeon, Ho-Seung [Sung Ae General Hospital, Department of Orthopedic Surgery, Seoul (Korea); Kim, Jang Min [Sung Ae General Hospital, Department of Radiology, Seoul (Korea); Park, Jung Mee; Kim, Sung-Hoon; Chung, Soo-Kyo [The Catholic University of Korea, Department of Radiology, College of Medicine, Seoul (Korea); Chung, Yong-An [The Catholic University of Korea, Department of Radiology, College of Medicine, Seoul (Korea); Incheon St. Mary' s Hospital, Institute of Catholic Integrative Medicine (ICIM), Incheon (Korea); Incheon St. Mary' s Hospital, The Catholic University of Korea, Department of Radiology, Incheon (Korea); Kim, E.E. [University of Texas MD Anderson Cancer Center, Department of Radiology and Nuclear Medicine, Houston, TX (United States)

    2010-08-15

    The aim of this study was to introduce gamma correction pinhole bone scan (GCPBS) to depict specific signs of knee occult fractures (OF) on {sup 99m}Tc-hydroxydiphosphonate (HDP) scan. Thirty-six cases of six different types of knee OF in 27 consecutive patients (male = 20, female = 7, and age = 18-86 years) were enrolled. The diagnosis was made on the basis of a history of acute or subacute knee trauma, local pain, tenderness, cutaneous injury, negative conventional radiography, and positive magnetic resonance imaging (MRI). Because of the impracticability of histological verification of individual OF, MRI was utilized as a gold standard of diagnosis and classification. All patients had {sup 99m}Tc-HDP bone scanning and supplementary GCPBS. GCPBS signs were correlated and compared with those of MRI. The efficacy of gamma correction of ordinary parallel collimator and pinhole collimator scans were collated. Gamma correction pinhole bone scan depicted the signs characteristic of six different types of OF. They were well defined stuffed globular tracer uptake in geographic I fractures (n = 9), block-like uptake in geographic II fractures (n = 7), simple or branching linear uptake in linear cancellous fractures (n = 4), compression in impacted fractures (n = 2), stippled-serpentine uptake in reticular fractures (n = 11), and irregular subcortical uptake in osteochondral fractures (n = 3). All fractures were equally well or more distinctly depicted on GCPBS than on MRI except geographic II fracture, the details of which were not appreciated on GCPBS. Parallel collimator scan also yielded to gamma correction, but the results were inferior to those of the pinhole scan. Gamma correction pinhole bone scan can depict the specific diagnostic signs in six different types of knee occult fractures. The specific diagnostic capability along with the lower cost and wider global availability of bone scanning would make GCPBS an effective alternative. (orig.)

  13. Novel use of gamma correction for precise 99mTc-HDP pinhole bone scan diagnosis and classification of knee occult fractures

    International Nuclear Information System (INIS)

    Bahk, Yong-Whee; Jeon, Ho-Seung; Kim, Jang Min; Park, Jung Mee; Kim, Sung-Hoon; Chung, Soo-Kyo; Chung, Yong-An; Kim, E.E.

    2010-01-01

    The aim of this study was to introduce gamma correction pinhole bone scan (GCPBS) to depict specific signs of knee occult fractures (OF) on 99m Tc-hydroxydiphosphonate (HDP) scan. Thirty-six cases of six different types of knee OF in 27 consecutive patients (male = 20, female = 7, and age = 18-86 years) were enrolled. The diagnosis was made on the basis of a history of acute or subacute knee trauma, local pain, tenderness, cutaneous injury, negative conventional radiography, and positive magnetic resonance imaging (MRI). Because of the impracticability of histological verification of individual OF, MRI was utilized as a gold standard of diagnosis and classification. All patients had 99m Tc-HDP bone scanning and supplementary GCPBS. GCPBS signs were correlated and compared with those of MRI. The efficacy of gamma correction of ordinary parallel collimator and pinhole collimator scans were collated. Gamma correction pinhole bone scan depicted the signs characteristic of six different types of OF. They were well defined stuffed globular tracer uptake in geographic I fractures (n = 9), block-like uptake in geographic II fractures (n = 7), simple or branching linear uptake in linear cancellous fractures (n = 4), compression in impacted fractures (n = 2), stippled-serpentine uptake in reticular fractures (n = 11), and irregular subcortical uptake in osteochondral fractures (n = 3). All fractures were equally well or more distinctly depicted on GCPBS than on MRI except geographic II fracture, the details of which were not appreciated on GCPBS. Parallel collimator scan also yielded to gamma correction, but the results were inferior to those of the pinhole scan. Gamma correction pinhole bone scan can depict the specific diagnostic signs in six different types of knee occult fractures. The specific diagnostic capability along with the lower cost and wider global availability of bone scanning would make GCPBS an effective alternative. (orig.)

  14. Effect of aberrations in human eye on contrast sensitivity function

    Science.gov (United States)

    Quan, Wei; Wang, Feng-lin; Wang, Zhao-qi

    2011-06-01

    The quantitative analysis of the effect of aberrations in human eye on vision has important clinical value in the correction of aberrations. The wave-front aberrations of human eyes were measured with the Hartmann-Shack wave-front sensor and modulation transfer function (MTF) was computed from the wave-front aberrations. Contrast sensitivity function (CSF) was obtained from MTF and the retinal aerial image modulation (AIM). It is shown that the 2nd, 3rd, 4th, 5th, 6th Zernike aberrations deteriorate contrast sensitivity function. When the 2nd, 3rd, 4th, 5th, 6th Zernike aberrations are corrected high contrast sensitivity function can be obtained.

  15. Rooting Out Aberrant Behavior in Training.

    Science.gov (United States)

    Kokalis, Jerry, Jr.; Paquin, Dave

    1989-01-01

    Discusses aberrant, or disruptive, behavior in an industrial/business, classroom-based, instructor-led training setting. Three examples of aberrant behavior are described, typical case studies are provided for each, and preventive (long-term) and corrective (on-the-spot) strategies for dealing with the problems are discussed. (LRW)

  16. Methods for Motion Correction Evaluation Using 18F-FDG Human Brain Scans on a High-Resolution PET Scanner

    DEFF Research Database (Denmark)

    Keller, Sune H.; Sibomana, Merence; Olesen, Oline Vinter

    2012-01-01

    Many authors have reported the importance of motion correction (MC) for PET. Patient motion during scanning disturbs kinetic analysis and degrades resolution. In addition, using misaligned transmission for attenuation and scatter correction may produce regional quantification bias in the reconstr......Many authors have reported the importance of motion correction (MC) for PET. Patient motion during scanning disturbs kinetic analysis and degrades resolution. In addition, using misaligned transmission for attenuation and scatter correction may produce regional quantification bias...... in the reconstructed emission images. The purpose of this work was the development of quality control (QC) methods for MC procedures based on external motion tracking (EMT) for human scanning using an optical motion tracking system. Methods: Two scans with minor motion and 5 with major motion (as reported...... (automated image registration) software. The following 3 QC methods were used to evaluate the EMT and AIR MC: a method using the ratio between 2 regions of interest with gray matter voxels (GM) and white matter voxels (WM), called GM/WM; mutual information; and cross correlation. Results: The results...

  17. Compensation of aberrations of deflected electron probe by means of dynamical focusing with stigmator

    International Nuclear Information System (INIS)

    Baba, Norio; Ebe, Toyoe; Ikehata, Koichi; Ito, Yasuhiro; Terada, Hiroshi

    1979-01-01

    Electron beam passing through a deflecting field is in general, subjected to aberrations such as distortion, astigmatism and coma in accordance with the deflecting angle. Accordingly the aberration defect of deflected beam is the most serious limiting factor in the performances of micromachining, microminiaturization and high resolution scanning electron microscopes. From many investigators' results, it is obvious that three important compensation methods to aberrations exist in principle, i.e., double deflection system, dynamical focusing, and the dynamical correction using a stigmator. In this paper, based on the aberration formula derived from the eikonal or the path method, the practical data of the aberration constants of deflected electron beam for the sequential deflection system with parallel plates are calculated, and using its result, the distorted spot patterns of an electron probe deflected in two-dimensional directions for various defocusings are graphically displayed by the aid of a computer. Further, by means of the dynamical focusing with a stigmator, the conditions to completely compensate the second order astigmatic aberration are derived, and spot patterns and the electron density distributions within the spots in the case when the compensating conditions are satisfied are also graphically displayed. (Wakatsuki, Y.)

  18. HEAVY ION FUSION SCIENCE VIRTUAL NATIONAL LABORATORY 1ST QUARTER 2010 MILESTONE REPORT: Simulations of fast correction of chromatic aberrations to establish physics specifications for implementation on NDCX-1 and NDCX-2

    International Nuclear Information System (INIS)

    Lidia, S.M.; Lund, S.M.; Seidl, P.A.

    2010-01-01

    This milestone has been accomplished. The Heavy Ion Fusion Science Virtual National Laboratory has completed simulations of a fast correction scheme to compensate for chromatic and time-dependent defocusing effects in the transport of ion beams to the target plane in the NDCX-1 facility. Physics specifications for implementation in NDCX-1 and NDCX-2 have been established. This milestone has been accomplished. The Heavy Ion Fusion Science Virtual National Laboratory has completed simulations of a fast correction scheme to compensate for chromatic and time-dependent defocusing effects in the transport of ion beams to the target plane in the NDCX-1 facility. Physics specifications for implementation in NDCX-1 and NDCX-2 have been established. Focal spot differences at the target plane between the compressed and uncompressed regions of the beam pulse have been modeled and measured on NDCX-1. Time-dependent focusing and energy sweep from the induction bunching module are seen to increase the compressed pulse spot size at the target plane by factors of two or more, with corresponding scaled reduction in the peak intensity and fluence on target. A time-varying beam envelope correction lens has been suggested to remove the time-varying aberration. An Einzel (axisymmetric electric) lens system has been analyzed and optimized for general transport lines, and as a candidate correction element for NDCX-1. Attainable high-voltage holdoff and temporal variations of the lens driving waveform are seen to effect significant changes on the beam envelope angle over the duration of interest, thus confirming the utility of such an element on NDCX-1. Modeling of the beam dynamics in NDCX-1 was performed using a time-dependent (slice) envelope code and with the 3-D, self-consistent, particle-in-cell code WARP. Proof of concept was established with the slice envelope model such that the spread in beam waist positions relative to the target plane can be minimized with a carefully designed

  19. Towards quantitative analysis of core-shell catalyst nano-particles by aberration corrected high angle annular dark field STEM and EDX

    International Nuclear Information System (INIS)

    Haibo, E; Nellist, P D; Lozano-Perez, S; Ozkaya, D

    2010-01-01

    Core-shell structured heterogeneous catalyst nano-particles offer the promise of more efficient precious metal usage and also novel functionalities but are as yet poorly characterised due to large compositional variations over short ranges. High angle annular dark field detector in a scanning transmission electron microscope is frequently used to image at high resolution because of its Z-contrast and incoherent imaging process, but generally little attention is paid to quantification. Energy dispersive X-ray analysis provides information on thickness and chemical composition and, used in conjunction with HAADF-STEM, aids interpretation of imaged nano-particles. We present important calibrations and initial data for truly quantitative high resolution analysis.

  20. Head motion evaluation and correction for PET scans with 18F-FDG in the Japanese Alzheimer's disease neuroimaging initiative (J-ADNI) multi-center study.

    Science.gov (United States)

    Ikari, Yasuhiko; Nishio, Tomoyuki; Makishi, Yoko; Miya, Yukari; Ito, Kengo; Koeppe, Robert A; Senda, Michio

    2012-08-01

    Head motion during 30-min (six 5-min frames) brain PET scans starting 30 min post-injection of FDG was evaluated together with the effect of post hoc motion correction between frames in J-ADNI multicenter study carried out in 24 PET centers on a total of 172 subjects consisting of 81 normal subjects, 55 mild cognitive impairment (MCI) and 36 mild Alzheimer's disease (AD) patients. Based on the magnitude of the between-frame co-registration parameters, the scans were classified into six levels (A-F) of motion degree. The effect of motion and its correction was evaluated using between-frame variation of the regional FDG uptake values on ROIs placed over cerebral cortical areas. Although AD patients tended to present larger motion (motion level E or F in 22 % of the subjects) than MCI (3 %) and normal (4 %) subjects, unignorable motion was observed in a small number of subjects in the latter groups as well. The between-frame coefficient of variation (SD/mean) was 0.5 % in the frontal, 0.6 % in the parietal and 1.8 % in the posterior cingulate ROI for the scans of motion level 1. The respective values were 1.5, 1.4, and 3.6 % for the scans of motion level F, but reduced by the motion correction to 0.5, 0.4 and 0.8 %, respectively. The motion correction changed the ROI value for the posterior cingulate cortex by 11.6 % in the case of severest motion. Substantial head motion occurs in a fraction of subjects in a multicenter setup which includes PET centers lacking sufficient experience in imaging demented patients. A simple frame-by-frame co-registration technique that can be applied to any PET camera model is effective in correcting for motion and improving quantitative capability.

  1. Evaluation of the ICS and DEW scatter correction methods for low statistical content scans in 3D PET

    International Nuclear Information System (INIS)

    Sossi, V.; Oakes, T.R.; Ruth, T.J.

    1996-01-01

    The performance of the Integral Convolution and the Dual Energy Window scatter correction methods in 3D PET has been evaluated over a wide range of statistical content of acquired data (1M to 400M events) The order in which scatter correction and detector normalization should be applied has also been investigated. Phantom and human neuroreceptor studies were used with the following figures of merit: axial and radial uniformity, sinogram and image noise, contrast accuracy and contrast accuracy uniformity. Both scatter correction methods perform reliably in the range of number of events examined. Normalization applied after scatter correction yields better radial uniformity and fewer image artifacts

  2. Aberration characteristics of immersion lenses for LVSEM

    International Nuclear Information System (INIS)

    Khursheed, Anjam

    2002-01-01

    This paper investigates the on-axis aberration characteristics of various immersion objective lenses for low voltage scanning electron microscopy (LVSEM). A simple aperture lens model is used to generate smooth axial field distributions. The simulation results show that mixed field electric-magnetic immersion lenses are predicted to have between 1.5 and 2 times smaller aberration limited probe diameters than their pure-field counterparts. At a landing energy of 1 keV, mixed field immersion lenses operating at the vacuum electrical field breakdown limit are predicted to have on-axis aberration coefficients between 50 and 60 μm, yielding an ultimate image resolution of below 1 nm. These aberrations lie in the same range as those for LVSEM systems that employ aberration correctors

  3. Third-rank chromatic aberrations of electron lenses.

    Science.gov (United States)

    Liu, Zhixiong

    2018-02-01

    In this paper the third-rank chromatic aberration coefficients of round electron lenses are analytically derived and numerically calculated by Mathematica. Furthermore, the numerical results are cross-checked by the differential algebraic (DA) method, which verifies that all the formulas for the third-rank chromatic aberration coefficients are completely correct. It is hoped that this work would be helpful for further chromatic aberration correction in electron microscopy. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. A study of respiration-correlated cone-beam CT scans to correct target positioning errors in radiotherapy of thoracic cancer

    Energy Technology Data Exchange (ETDEWEB)

    Santoro, J. P.; McNamara, J.; Yorke, E.; Pham, H.; Rimner, A.; Rosenzweig, K. E.; Mageras, G. S. [Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, New York 10065 (United States); Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, New York 10065 (United States); Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, New York 10065 (United States)

    2012-10-15

    Purpose: There is increasingly widespread usage of cone-beam CT (CBCT) for guiding radiation treatment in advanced-stage lung tumors, but difficulties associated with daily CBCT in conventionally fractionated treatments include imaging dose to the patient, increased workload and longer treatment times. Respiration-correlated cone-beam CT (RC-CBCT) can improve localization accuracy in mobile lung tumors, but further increases the time and workload for conventionally fractionated treatments. This study investigates whether RC-CBCT-guided correction of systematic tumor deviations in standard fractionated lung tumor radiation treatments is more effective than 2D image-based correction of skeletal deviations alone. A second study goal compares respiration-correlated vs respiration-averaged images for determining tumor deviations. Methods: Eleven stage II-IV nonsmall cell lung cancer patients are enrolled in an IRB-approved prospective off-line protocol using RC-CBCT guidance to correct for systematic errors in GTV position. Patients receive a respiration-correlated planning CT (RCCT) at simulation, daily kilovoltage RC-CBCT scans during the first week of treatment and weekly scans thereafter. Four types of correction methods are compared: (1) systematic error in gross tumor volume (GTV) position, (2) systematic error in skeletal anatomy, (3) daily skeletal corrections, and (4) weekly skeletal corrections. The comparison is in terms of weighted average of the residual GTV deviations measured from the RC-CBCT scans and representing the estimated residual deviation over the treatment course. In the second study goal, GTV deviations computed from matching RCCT and RC-CBCT are compared to deviations computed from matching respiration-averaged images consisting of a CBCT reconstructed using all projections and an average-intensity-projection CT computed from the RCCT. Results: Of the eleven patients in the GTV-based systematic correction protocol, two required no correction

  5. A study of respiration-correlated cone-beam CT scans to correct target positioning errors in radiotherapy of thoracic cancer

    International Nuclear Information System (INIS)

    Santoro, J. P.; McNamara, J.; Yorke, E.; Pham, H.; Rimner, A.; Rosenzweig, K. E.; Mageras, G. S.

    2012-01-01

    Purpose: There is increasingly widespread usage of cone-beam CT (CBCT) for guiding radiation treatment in advanced-stage lung tumors, but difficulties associated with daily CBCT in conventionally fractionated treatments include imaging dose to the patient, increased workload and longer treatment times. Respiration-correlated cone-beam CT (RC-CBCT) can improve localization accuracy in mobile lung tumors, but further increases the time and workload for conventionally fractionated treatments. This study investigates whether RC-CBCT-guided correction of systematic tumor deviations in standard fractionated lung tumor radiation treatments is more effective than 2D image-based correction of skeletal deviations alone. A second study goal compares respiration-correlated vs respiration-averaged images for determining tumor deviations. Methods: Eleven stage II–IV nonsmall cell lung cancer patients are enrolled in an IRB-approved prospective off-line protocol using RC-CBCT guidance to correct for systematic errors in GTV position. Patients receive a respiration-correlated planning CT (RCCT) at simulation, daily kilovoltage RC-CBCT scans during the first week of treatment and weekly scans thereafter. Four types of correction methods are compared: (1) systematic error in gross tumor volume (GTV) position, (2) systematic error in skeletal anatomy, (3) daily skeletal corrections, and (4) weekly skeletal corrections. The comparison is in terms of weighted average of the residual GTV deviations measured from the RC-CBCT scans and representing the estimated residual deviation over the treatment course. In the second study goal, GTV deviations computed from matching RCCT and RC-CBCT are compared to deviations computed from matching respiration-averaged images consisting of a CBCT reconstructed using all projections and an average-intensity-projection CT computed from the RCCT. Results: Of the eleven patients in the GTV-based systematic correction protocol, two required no correction

  6. Pixelized measurement of {sup 99m}Tc-HDP micro particles formed in gamma correction phantom pinhole scan: A reference study

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Joo Young; Yoon, Do Kyun; Chung, Yong An [Catholic University of Korea, College of Medicine, Seoul (Korea, Republic of); Cheon, Gi Jeong; Lee, Yun Sang; Ha, Seunggyun [Radiopharmaceutical Science Laboratory, Dept. of Nuclear MedicineSeoul National University, College of Medicine, Seoul (Korea, Republic of); Bahk, Yong Whee [Dept. of Nuclear Medicine, Sung Ae General Hospital, Seoul (Korea, Republic of)

    2016-09-15

    Currently, traumatic bone diseases are diagnosed by assessing the micro {sup 99m}Tc-hydroxymethylene diphosphonate (HDP) uptake in injured trabeculae with ongoing osteoneogenesis demonstrated by gamma correction pinhole scan (GCPS). However, the mathematic size quantification of micro-uptake is not yet available. We designed and performed this phantom-based study to set up an in-vitro model of the mathematical calculation of micro-uptake by the pixelized measurement. The micro {sup 99m}Tc-HDP deposits used in this study were spontaneously formed both in a large standard flood and small house-made dish phantoms. The processing was as follows: first, phantoms were flooded with distilled water and {sup 99m}Tc-HDP was therein injected to induce micro {sup 99m}Tc-HDP deposition; second, the deposits were scanned using parallel-hole and pinhole collimator to generally survey {sup 99m}Tc-HDP deposition pattern; and third, the scans underwent gamma correction (GC) to discern individual deposits for size measurement. In original naïve scans, tracer distribution was simply nebulous in appearance and, hence, could not be measured. Impressively, however, GCPS could discern individual micro deposits so that they were calculated by pixelized measurement. Phantoms naturally formed micro {sup 99m}Tc-HDP deposits that are analogous to {sup 99m}Tc-HDP uptake on in-vivo bone scan. The smallest one we measured was 0.414 mm. Flooded phantoms and therein injected {sup 99m}Tc-HDP form nebulous micro {sup 99m}Tc-HDP deposits that are rendered discernible by GCPB and precisely calculable using pixelized measurement. This method can be used for precise quantitative and qualitative diagnosis of bone and joint diseases at the trabecular level.

  7. Environmental TEM in an Aberration Corrected Microscope

    DEFF Research Database (Denmark)

    Hansen, Thomas Willum; Wagner, Jakob Birkedal

    ‐resolution imaging. A gaseous atmosphere in the pole‐piece gap of the objective lens of the microscope alters both the incoming electron wave prior to interaction with the sample and the outgoing wave below the sample. Whereas conventional TEM samples are usually thin (below 10‐20 nm), the gas in the environmental...... the microscope column. The effects of gas on the electron wave in the objective lens are not well understood and needs further attention. Imaging samples with a simple geometry, such as gold particles on a flat graphene substrate and analyzing the variations in contrast, provides a means for understanding...... results from imaging in various elemental as well as di‐molecular gases and their effect on imaging and spectroscopy in the environmental transmission electron microscope....

  8. Higher order aberrations in amblyopic children and their role in refractory amblyopia

    Directory of Open Access Journals (Sweden)

    Arnaldo Dias-Santos

    2014-12-01

    Full Text Available Objective: Some studies have hypothesized that an unfavourable higher order aberrometric profile could act as an amblyogenic mechanism and may be responsible for some amblyopic cases that are refractory to conventional treatment or cases of “idiopathic” amblyopia. This study compared the aberrometric profile in amblyopic children to that of children with normal visual development and compared the aberrometric profile in corrected amblyopic eyes and refractory amblyopic eyes with that of healthy eyes. Methods: Cross-sectional study with three groups of children – the CA group (22 eyes of 11 children with unilateral corrected amblyopia, the RA group (24 eyes of 13 children with unilateral refractory amblyopia and the C group (28 eyes of 14 children with normal visual development. Higher order aberrations were evaluated using an OPD-Scan III (NIDEK. Comparisons of the aberrometric profile were made between these groups as well as between the amblyopic and healthy eyes within the CA and RA groups. Results: Higher order aberrations with greater impact in visual quality were not significantly higher in the CA and RA groups when compared with the C group. Moreover, there were no statistically significant differences in the higher order aberrometric profile between the amblyopic and healthy eyes within the CA and RA groups. Conclusions: Contrary to lower order aberrations (e.g., myopia, hyperopia, primary astigmatism, higher order aberrations do not seem to be involved in the etiopathogenesis of amblyopia. Therefore, these are likely not the cause of most cases of refractory amblyopia.

  9. Subject-specific bone attenuation correction for brain PET/MR: can ZTE-MRI substitute CT scan accurately?

    Science.gov (United States)

    Khalifé, Maya; Fernandez, Brice; Jaubert, Olivier; Soussan, Michael; Brulon, Vincent; Buvat, Irène; Comtat, Claude

    2017-10-01

    In brain PET/MR applications, accurate attenuation maps are required for accurate PET image quantification. An implemented attenuation correction (AC) method for brain imaging is the single-atlas approach that estimates an AC map from an averaged CT template. As an alternative, we propose to use a zero echo time (ZTE) pulse sequence to segment bone, air and soft tissue. A linear relationship between histogram normalized ZTE intensity and measured CT density in Hounsfield units (HU ) in bone has been established thanks to a CT-MR database of 16 patients. Continuous AC maps were computed based on the segmented ZTE by setting a fixed linear attenuation coefficient (LAC) to air and soft tissue and by using the linear relationship to generate continuous μ values for the bone. Additionally, for the purpose of comparison, four other AC maps were generated: a ZTE derived AC map with a fixed LAC for the bone, an AC map based on the single-atlas approach as provided by the PET/MR manufacturer, a soft-tissue only AC map and, finally, the CT derived attenuation map used as the gold standard (CTAC). All these AC maps were used with different levels of smoothing for PET image reconstruction with and without time-of-flight (TOF). The subject-specific AC map generated by combining ZTE-based segmentation and linear scaling of the normalized ZTE signal into HU was found to be a good substitute for the measured CTAC map in brain PET/MR when used with a Gaussian smoothing kernel of 4~mm corresponding to the PET scanner intrinsic resolution. As expected TOF reduces AC error regardless of the AC method. The continuous ZTE-AC performed better than the other alternative MR derived AC methods, reducing the quantification error between the MRAC corrected PET image and the reference CTAC corrected PET image.

  10. On the sensitivity of probe-corrected spherical near-field antenna measurements with high-order probes using double phi-step theta-scanning scheme against various measurement uncertainties

    DEFF Research Database (Denmark)

    Laitinen, Tommi; Pivnenko, Sergey; Nielsen, Jeppe Majlund

    2011-01-01

    In this paper, the relatively recently introduced double phi-step theta-scanning scheme and the probe correction technique associated with it is examined against the traditional phi-scanning scheme and the first-order probe correction. The important result of this paper is that the double phi......-step theta-scanning scheme is shown to be clearly less sensitive to the probe misalignment errors compared to the phi-scanning scheme. The two methods show similar sensitivity to noise and channel balance error....

  11. Simulation-based validation and arrival-time correction for Patlak analyses of Perfusion-CT scans

    Science.gov (United States)

    Bredno, Jörg; Hom, Jason; Schneider, Thomas; Wintermark, Max

    2009-02-01

    Blood-brain-barrier (BBB) breakdown is a hypothesized mechanism for hemorrhagic transformation in acute stroke. The Patlak analysis of a Perfusion Computed Tomography (PCT) scan measures the BBB permeability, but the method yields higher estimates when applied to the first pass of the contrast bolus compared to a delayed phase. We present a numerical phantom that simulates vascular and parenchymal time-attenuation curves to determine the validity of permeability measurements obtained with different acquisition protocols. A network of tubes represents the major cerebral arteries ipsi- and contralateral to an ischemic event. These tubes branch off into smaller segments that represent capillary beds. Blood flow in the phantom is freely defined and simulated as non-Newtonian tubular flow. Diffusion of contrast in the vessels and permeation through vessel walls is part of the simulation. The phantom allows us to compare the results of a permeability measurement to the simulated vessel wall status. A Patlak analysis reliably detects areas with BBB breakdown for acquisitions of 240s duration, whereas results obtained from the first pass are biased in areas of reduced blood flow. Compensating for differences in contrast arrival times reduces this bias and gives good estimates of BBB permeability for PCT acquisitions of 90-150s duration.

  12. Evaluating the Correctness of Airborne Laser Scanning Data Heights Using Vehicle-Based RTK and VRS GPS Observations

    Directory of Open Access Journals (Sweden)

    Martin Vermeer

    2011-08-01

    Full Text Available In this study, we describe a system in which a GPS receiver mounted on the roof of a car is used to provide reference information to evaluate the elevation accuracy and georeferencing of airborne laser scanning (ALS point clouds. The concept was evaluated in the Klaukkala test area where a number of roads were traversed to collect real-time kinematic data. Two test cases were evaluated, including one case using the real-time kinematic (RTK method with a dedicated GPS base station at a known benchmark in the area and another case using the GNSSnet virtual reference station service (VRS. The utility of both GPS methods was confirmed. When all test data were included, the mean difference between ALS data and GPS-based observations was −2.4 cm for both RTK and VRS GPS cases. The corresponding dispersions were ±4.5 cm and ±5.9 cm, respectively. In addition, our examination did not reveal the presence of any significant rotation between ALS and GPS data.

  13. Fiducial marker-based correction for involuntary motion in weight-bearing C-arm CT scanning of knees. II. Experiment

    International Nuclear Information System (INIS)

    Choi, Jang-Hwan; Maier, Andreas; Keil, Andreas; McWalter, Emily J.; Gold, Garry E.; Fahrig, Rebecca; Pal, Saikat; Beaupré, Gary S.

    2014-01-01

    Purpose: A C-arm CT system has been shown to be capable of scanning a single cadaver leg under loaded conditions by virtue of its highly flexible acquisition trajectories. In Part I of this study, using the 4D XCAT-based numerical simulation, the authors predicted that the involuntary motion in the lower body of subjects in weight-bearing positions would seriously degrade image quality and the authors suggested three motion compensation methods by which the reconstructions could be corrected to provide diagnostic image quality. Here, the authors demonstrate that a flat-panel angiography system is appropriate for scanning both legs of subjectsin vivo under weight-bearing conditions and further evaluate the three motion-correction algorithms using in vivo data. Methods: The geometry of a C-arm CT system for a horizontal scan trajectory was calibrated using the PDS-2 phantom. The authors acquired images of two healthy volunteers while lying supine on a table, standing, and squatting at several knee flexion angles. In order to identify the involuntary motion of the lower body, nine 1-mm-diameter tantalum fiducial markers were attached around the knee. The static mean marker position in 3D, a reference for motion compensation, was estimated by back-projecting detected markers in multiple projections using calibrated projection matrices and identifying the intersection points in 3D of the back-projected rays. Motion was corrected using three different methods (described in detail previously): (1) 2D projection shifting, (2) 2D deformable projection warping, and (3) 3D rigid body warping. For quantitative image quality analysis, SSIM indices for the three methods were compared using the supine data as a ground truth. Results: A 2D Euclidean distance-based metric of subjects’ motion ranged from 0.85 mm (±0.49 mm) to 3.82 mm (±2.91 mm) (corresponding to 2.76 to 12.41 pixels) resulting in severe motion artifacts in 3D reconstructions. Shifting in 2D, 2D warping, and 3D

  14. Simulação computacional de cirurgias foto-refrativas personalizadas e precisão relacionada à ordem das aberrações ópticas Computational simulation of customized photorefractive surgery and precision of correction related to different order aberrations

    Directory of Open Access Journals (Sweden)

    Luis Alberto Vieira de Carvalho

    2007-12-01

    Full Text Available O objetivo principal deste trabalho foi o desenvolvimento e a implementação de um algoritmo para simulação de cirurgias foto-refrativas. Sabe-se que os atuais " flying-spot" lasers para cirurgia refrativa disponíveis no mercado ainda contêm limitações na correção de algumas aberrações de ordem alta. No entanto, há muito pouca informação quantitativa sobre os erros envolvidos em função da complexidade das aberrações. Aplicando-se superfícies objetivo descritas por uma série de coeficientes de Zernike e o conceito matemático de convolução, várias ablações personalizadas foram simuladas para várias aberrações, desde baixa ordem (esfero-cilíndricas até aberrações de décima ordem (como coma, aberração esférica, entre outras. Os resultados mostram que o perfil de ablação de cada pulso do laser assim como seu diâmetro são fatores críticos quando o objetivo é corrigir aberrações de alta ordem. Além disso, outras conclusões foram possíveis, como por exemplo a de que nem todas as aberrações de alta ordem induzem aos mesmos erros na ablação. Também foi possível verificar que a correção de aberrações de alta ordem nos termos radiais (como aberração esférica é bem mais difícil do que naqueles termos contendo alta frequência angular (como trefoil.PURPOSE: To develop and implement an algorithm for simulation of photorefractive surgery. It is well known that many flying-spot lasers in the market have limitations in correcting higher order aberrations, but there is little quantitative information about errors related to aberration complexity. METHODS: By applying known surfaces described by Zernike polynomials of different orders it was possible to simulate several target surfaces that may well resemble in vivo cases of refractive surgery candidates. An algorithm that uses the mathematical concept of convolution was implemented and several simulated surfaces were tested, ranging from low order

  15. Alteration of introns in a hyaluronan synthase 1 (HAS1 minigene convert Pre-mRNA [corrected] splicing to the aberrant pattern in multiple myeloma (MM: MM patients harbor similar changes.

    Directory of Open Access Journals (Sweden)

    Jitra Kriangkum

    Full Text Available Aberrant pre-mRNA splice variants of hyaluronan synthase 1 (HAS1 have been identified in malignant cells from cancer patients. Bioinformatic analysis suggests that intronic sequence changes can underlie aberrant splicing. Deletions and mutations were introduced into HAS1 minigene constructs to identify regions that can influence aberrant intronic splicing, comparing the splicing pattern in transfectants with that in multiple myeloma (MM patients. Introduced genetic variations in introns 3 and 4 of HAS1 as shown here can promote aberrant splicing of the type detected in malignant cells from MM patients. HAS1Vd is a novel intronic splice variant first identified here. HAS1Vb, an intronic splice variant previously identified in patients, skips exon 4 and utilizes the same intron 4 alternative 3'splice site as HAS1Vd. For transfected constructs with unaltered introns 3 and 4, HAS1Vd transcripts are readily detectable, frequently to the exclusion of HAS1Vb. In contrast, in MM patients, HAS1Vb is more frequent than HAS1Vd. In the HAS1 minigene, combining deletion in intron 4 with mutations in intron 3 leads to a shift from HAS1Vd expression to HAS1Vb expression. The upregulation of aberrant splicing, exemplified here by the expression of HAS1Vb, is shown here to be influenced by multiple genetic changes in intronic sequences. For HAS1Vb, this includes enhanced exon 4 skipping and increased usage of alternative 3' splice sites. Thus, the combination of introduced mutations in HAS1 intron3 with introduced deletions in HAS1 intron 4 promoted a shift to an aberrant splicing pattern previously shown to be clinically significant. Most MM patients harbor genetic variations in intron 4, and as shown here, nearly half harbor recurrent mutations in HAS1 intron 3. Our work suggests that aberrant intronic HAS1 splicing in MM patients may rely on intronic HAS1 deletions and mutations that are frequent in MM patients but absent from healthy donors.

  16. Safety, Efficacy, Predictability and Stability Indices of Photorefractive Keratectomy for Correction of Myopic Astigmatism with Plano-Scan and Tissue-Saving Algorithms

    Directory of Open Access Journals (Sweden)

    Mehrdad Mohammadpour

    2013-10-01

    Full Text Available Purpose: To assess the safety, efficacy and predictability of photorefractive keratectomy (PRK [Tissue-saving (TS versus Plano-scan (PS ablation algorithms] of Technolas 217z excimer laser for correction of myopic astigmatismMethods: In this retrospective study one hundred and seventy eyes of 85 patients (107 eyes (62.9% with PS and 63 eyes (37.1% with TS algorithm were included. TS algorithm was applied for those with central corneal thickness less than 500 µm or estimated residual stromal thickness less than 420 µm. Mitomycin C (MMC was applied for 120 eyes (70.6%; in case of an ablation depth more than 60 μm and/or astigmatic correction more than one diopter (D. Mean sphere, cylinder, spherical equivalent (SE refraction, uncorrected visual acuity (UCVA, best corrected visual acuity (BCVA were measured preoperatively, and 4 weeks,12 weeks and 24 weeks postoperatively.Results: One, three and six months postoperatively, 60%, 92.9%, 97.5% of eyes had UCVA of 20/20 or better, respectively. Mean preoperative and 1, 3, 6 months postoperative SE were -3.48±1.28 D (-1.00 to -8.75, -0.08±0.62D, -0.02±0.57 and -0.004± 0.29, respectively. And also, 87.6%, 94.1% and 100% were within ±1.0 D of emmetropia and 68.2, 75.3, 95% were within ±0.5 of emmetropia. The safety and efficacy indices were 0.99 and 0.99 at 12 weeks and 1.009 and 0.99 at 24 weeks, respectively. There was no clinically or statistically significant difference between the outcomes of PS or TS algorithms or between those with or without MMC in either group in terms of safety, efficacy, predictability or stability. Dividing the eyes with subjective SE≤4 D and SE≥4 D postoperatively, there was no significant difference between the predictability of the two groups. There was no intra- or postoperative complication.Conclusion: Outcomes of PRK for correction of myopic astigmatism showed great promise with both PS and TS algorithms.

  17. Estimation of dose from chromosome aberration rate

    International Nuclear Information System (INIS)

    Li Deping

    1990-01-01

    The methods and skills of evaluating dose from correctly scored shromsome aberration rate are presented, and supplemented with corresponding BASIC computer code. The possibility and preventive measures of excessive probability of missing score of the aberrations in some of the current routine score methods are discussed. The use of dose-effect relationship with exposure time correction factor G in evaluating doses and their confidence intervals, dose estimation in mixed n-γ exposure, and identification of high by nonuniform acute exposure to low LET radiation and its dose estimation are discussed in more detail. The difference of estimated dose due to whether the interaction between subleisoms produced by n and γ have been taken into account is examined. In fitting the standard dose-aberration rate curve, proper weighing of experiment points and comparison with commonly accepted values are emphasised, and the coefficient of variation σ y √y of the aberration rate y as a function of dose and exposure time is given. In appendix I and II, the dose-aberration rate formula is derived from dual action theory, and the time variation of subleisom is illustrated and in appendix III, the estimation of dose from scores of two different types of aberrations (of other related score) is illustrated. Two computer codes are given in appendix IV, one is a simple code, the other a complete code, including the fitting of standard curve. the skills of using compressed data storage, and the production of simulated 'data ' for testing the curve fitting procedure are also given

  18. Spherical aberrations of human astigmatic corneas.

    Science.gov (United States)

    Zhao, Huawei; Dai, Guang-Ming; Chen, Li; Weeber, Henk A; Piers, Patricia A

    2011-11-01

    To evaluate whether the average spherical aberration of human astigmatic corneas is statistically equivalent to human nonastigmatic corneas. Spherical aberrations of 445 astigmatic corneas prior to laser vision correction were retrospectively investigated to determine Zernike coefficients for central corneal areas 6 mm in diameter using CTView (Sarver and Associates). Data were divided into groups according to cylinder power (0.01 to 0.25 diopters [D], 0.26 to 0.75 D, 0.76 to 1.06 D, 1.07 to 1.53 D, 1.54 to 2.00 D, and >2.00 D) and according to age by decade. Spherical aberrations were correlated with age and astigmatic power among groups and the entire population. Statistical analyses were conducted, and P.05 for all tested groups). Mean spherical aberration of astigmatic corneas was not correlated significantly with cylinder power or age (P>.05). Spherical aberrations are similar to those of nonastigmatic corneas, permitting the use of these additional data in the design of aspheric toric intra-ocular lenses. Copyright 2011, SLACK Incorporated.

  19. Whole eye wavefront aberrations in Mexican male subjects.

    Science.gov (United States)

    Cantú, Roberto; Rosales, Marco A; Tepichín, Eduardo; Curioca, Andrée; Montes, Victor; Bonilla, Julio

    2004-01-01

    To analyze the characteristics, incidence, and appearance of wavefront aberrations in undilated, normal, unoperated eyes. Eighty-eight eyes of 44 healthy male Mexican subjects (mean age 25.32 years, range 18 to 36 yr) were divided into three groups based on uncorrected visual acuity of greater than or equal to 20/20, 20/30, or 20/40. UCVA measurements were obtained using an Acuity Max computer screen chart. Wavefront aberrations were measured with the Nidek OPD-Scan ARK 10000, Ver. 1.11b. All measurements were carried out at the same center by the same technician during a single session, following manufacturer instructions. Background illumination was 3 Lux. Wavefront aberration measurements for each group were statistically analyzed using StatView; an average eye was characterized and the resulting aberrations were simulated using MATLAB. We obtained wavefront aberration maps for the 20/20 undilated normal unoperated eyes for total, low, and high order aberration coefficients. Wavefront maps for right eyes were practically the same as those for left eyes. Higher aberrations did not contribute substantially to total wavefront analysis. Average aberrations of this "normal eye" will be used as criteria to decide the necessity of wavefront-guided ablation in our facilities. We will focus on the nearly zero average of high order aberrations in this normal whole eye as a reference to be matched.

  20. Mutations and chromosomal aberrations

    International Nuclear Information System (INIS)

    Kihlman, B.A.

    1977-01-01

    The genetic changes of mutations and chromosomal aberrations are discussed. The consequences of both depend not only on the type of genetic change produced but also on the type of cell that is affected and on the development stage of the organism. (C.F.)

  1. Brillouin micro-spectroscopy through aberrations via sensorless adaptive optics

    Science.gov (United States)

    Edrei, Eitan; Scarcelli, Giuliano

    2018-04-01

    Brillouin spectroscopy is a powerful optical technique for non-contact viscoelastic characterizations which has recently found applications in three-dimensional mapping of biological samples. Brillouin spectroscopy performances are rapidly degraded by optical aberrations and have therefore been limited to homogenous transparent samples. In this work, we developed an adaptive optics (AO) configuration designed for Brillouin scattering spectroscopy to engineer the incident wavefront and correct for aberrations. Our configuration does not require direct wavefront sensing and the injection of a "guide-star"; hence, it can be implemented without the need for sample pre-treatment. We used our AO-Brillouin spectrometer in aberrated phantoms and biological samples and obtained improved precision and resolution of Brillouin spectral analysis; we demonstrated 2.5-fold enhancement in Brillouin signal strength and 1.4-fold improvement in axial resolution because of the correction of optical aberrations.

  2. SU-F-J-211: Scatter Correction for Clinical Cone-Beam CT System Using An Optimized Stationary Beam Blocker with a Single Scan

    Energy Technology Data Exchange (ETDEWEB)

    Liang, X; Zhang, Z; Xie, Y [Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, GuangDong (China); Gong, S; Niu, T [Department of Radiation Oncology, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang (China); Institute of Translational Medicine, Zhejiang University, Hangzhou, Zhejiang (China); Zhou, Q [Department of Radiation Oncology, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang (China)

    2016-06-15

    Purpose: X-ray scatter photons result in significant image quality degradation of cone-beam CT (CBCT). Measurement based algorithms using beam blocker directly acquire the scatter samples and achieve significant improvement on the quality of CBCT image. Within existing algorithms, single-scan and stationary beam blocker proposed previously is promising due to its simplicity and practicability. Although demonstrated effectively on tabletop system, the blocker fails to estimate the scatter distribution on clinical CBCT system mainly due to the gantry wobble. In addition, the uniform distributed blocker strips in our previous design results in primary data loss in the CBCT system and leads to the image artifacts due to data insufficiency. Methods: We investigate the motion behavior of the beam blocker in each projection and design an optimized non-uniform blocker strip distribution which accounts for the data insufficiency issue. An accurate scatter estimation is then achieved from the wobble modeling. Blocker wobble curve is estimated using threshold-based segmentation algorithms in each projection. In the blocker design optimization, the quality of final image is quantified using the number of the primary data loss voxels and the mesh adaptive direct search algorithm is applied to minimize the objective function. Scatter-corrected CT images are obtained using the optimized blocker. Results: The proposed method is evaluated using Catphan@504 phantom and a head patient. On the Catphan©504, our approach reduces the average CT number error from 115 Hounsfield unit (HU) to 11 HU in the selected regions of interest, and improves the image contrast by a factor of 1.45 in the high-contrast regions. On the head patient, the CT number error is reduced from 97 HU to 6 HU in the soft tissue region and image spatial non-uniformity is decreased from 27% to 5% after correction. Conclusion: The proposed optimized blocker design is practical and attractive for CBCT guided radiation

  3. SU-F-J-211: Scatter Correction for Clinical Cone-Beam CT System Using An Optimized Stationary Beam Blocker with a Single Scan

    International Nuclear Information System (INIS)

    Liang, X; Zhang, Z; Xie, Y; Gong, S; Niu, T; Zhou, Q

    2016-01-01

    Purpose: X-ray scatter photons result in significant image quality degradation of cone-beam CT (CBCT). Measurement based algorithms using beam blocker directly acquire the scatter samples and achieve significant improvement on the quality of CBCT image. Within existing algorithms, single-scan and stationary beam blocker proposed previously is promising due to its simplicity and practicability. Although demonstrated effectively on tabletop system, the blocker fails to estimate the scatter distribution on clinical CBCT system mainly due to the gantry wobble. In addition, the uniform distributed blocker strips in our previous design results in primary data loss in the CBCT system and leads to the image artifacts due to data insufficiency. Methods: We investigate the motion behavior of the beam blocker in each projection and design an optimized non-uniform blocker strip distribution which accounts for the data insufficiency issue. An accurate scatter estimation is then achieved from the wobble modeling. Blocker wobble curve is estimated using threshold-based segmentation algorithms in each projection. In the blocker design optimization, the quality of final image is quantified using the number of the primary data loss voxels and the mesh adaptive direct search algorithm is applied to minimize the objective function. Scatter-corrected CT images are obtained using the optimized blocker. Results: The proposed method is evaluated using Catphan@504 phantom and a head patient. On the Catphan©504, our approach reduces the average CT number error from 115 Hounsfield unit (HU) to 11 HU in the selected regions of interest, and improves the image contrast by a factor of 1.45 in the high-contrast regions. On the head patient, the CT number error is reduced from 97 HU to 6 HU in the soft tissue region and image spatial non-uniformity is decreased from 27% to 5% after correction. Conclusion: The proposed optimized blocker design is practical and attractive for CBCT guided radiation

  4. An accurate optical design method for synchrotron radiation beamlines with wave-front aberration theory

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Xiaojiang, E-mail: slsyxj@nus.edu.sg; Diao, Caozheng; Breese, Mark B. H. [Singapore Synchrotron Light Source, National University of Singapore, Singapore 117603 (Singapore)

    2016-07-27

    An aberration calculation method which was developed by Lu [1] can treat individual aberration term precisely. Spectral aberration is the linear sum of these aberration terms, and the aberrations of multi-element systems also can be calculated correctly when the stretching ratio, defined herein, is unity. Evaluation of focusing mirror-grating systems which are optimized according to Lu’s method, along with the Light Path Function (LPF) and the Spot Diagram method (SD) are discussed to confirm the advantage of Lu’s methodology. Lu’s aberration terms are derived from a precise wave-front treatment, whereas the terms of the power series expansion of the light path function do not yield an accurate sum of the aberrations. Moreover, Lu’s aberration terms can be individually optimized. This is not possible with the analytical spot diagram formulae.

  5. Aberrant hepatic artery

    International Nuclear Information System (INIS)

    Konstam, M.A.; Novelline, R.A.; Athanasoulis, C.A.

    1979-01-01

    In a patient undergoing selective hepatic arteriography for suspected liver trauma, a nonopacified area of the liver, initially thought to represent a hepatic hematoma, was later discovered to be due to the presence of an accessory right hepatic artery arising from the superior mesenteric artery. This case illustrates the need for a search for aberrant vasculature whenever a liver hematoma is suspected on the basis of a selective hepatic arteriogram. (orig.) [de

  6. Spectral estimation for characterization of acoustic aberration.

    Science.gov (United States)

    Varslot, Trond; Angelsen, Bjørn; Waag, Robert C

    2004-07-01

    Spectral estimation based on acoustic backscatter from a motionless stochastic medium is described for characterization of aberration in ultrasonic imaging. The underlying assumptions for the estimation are: The correlation length of the medium is short compared to the length of the transmitted acoustic pulse, an isoplanatic region of sufficient size exists around the focal point, and the backscatter can be modeled as an ergodic stochastic process. The motivation for this work is ultrasonic imaging with aberration correction. Measurements were performed using a two-dimensional array system with 80 x 80 transducer elements and an element pitch of 0.6 mm. The f number for the measurements was 1.2 and the center frequency was 3.0 MHz with a 53% bandwidth. Relative phase of aberration was extracted from estimated cross spectra using a robust least-mean-square-error method based on an orthogonal expansion of the phase differences of neighboring wave forms as a function of frequency. Estimates of cross-spectrum phase from measurements of random scattering through a tissue-mimicking aberrator have confidence bands approximately +/- 5 degrees wide. Both phase and magnitude are in good agreement with a reference characterization obtained from a point scatterer.

  7. Outline of an ultracorrector compensating for all primary chromatic and geometrical aberrations of charged-particle lenses

    International Nuclear Information System (INIS)

    Rose, Harald

    2004-01-01

    A novel ultracorrector is outlined which compensates for the primary and secondary first-order chromatic aberrations and all third-order geometrical aberrations of electron optical systems with a straight axis. Owing to the imposed symmetry conditions on the fields and the paraxial fundamental rays, the corrector does not introduce aberrations with 2-fold symmetry. The chromatic aberrations are corrected by means of crossed electric magnetic quadrupoles while the third-order geometrical aberrations are eliminated by octopoles. By placing these elements at distinct positions within the corrector, it is possible to successively eliminate the third-order aberrations in such a way that each subsequent correction does not affect the aberrations corrected in the preceding correction steps

  8. Aberration compensation using a spatial light modulator LCD

    International Nuclear Information System (INIS)

    Amezquita, R; Rincon, O; Torres, Y M

    2011-01-01

    The dynamic correction of aberrations introduced in optical systems have been a widely discussed topic in the past 10 years. Adaptive optics is the most important developed field where the Shack-Hartmann sensors and deformable mirrors are used for the measurement and correction of wavefronts. In this paper, an interferometric set-up which uses a Spatial Light Modulator (SLM) as an active element is proposed. Using this SLM a procedure for the compensation of all phase aberrations present in the experimental setup is shown.

  9. High-resolution adaptive optics scanning laser ophthalmoscope with multiple deformable mirrors

    Science.gov (United States)

    Chen, Diana C.; Olivier, Scot S.; Jones; Steven M.

    2010-02-23

    An adaptive optics scanning laser ophthalmoscopes is introduced to produce non-invasive views of the human retina. The use of dual deformable mirrors improved the dynamic range for correction of the wavefront aberrations compared with the use of the MEMS mirror alone, and improved the quality of the wavefront correction compared with the use of the bimorph mirror alone. The large-stroke bimorph deformable mirror improved the capability for axial sectioning with the confocal imaging system by providing an easier way to move the focus axially through different layers of the retina.

  10. Aberration studies and computer algebra

    International Nuclear Information System (INIS)

    Hawkes, P.W.

    1981-01-01

    The labour of calculating expressions for aberration coefficients is considerably lightened if a computer algebra language is used to perform the various substitutions and expansions involved. After a brief discussion of matrix representations of aberration coefficients, a particular language, which has shown itself to be well adapted to particle optics, is described and applied to the study of high frequency cavity lenses. (orig.)

  11. Effects of ocular aberrations on contrast detection in noise.

    Science.gov (United States)

    Liang, Bo; Liu, Rong; Dai, Yun; Zhou, Jiawei; Zhou, Yifeng; Zhang, Yudong

    2012-08-06

    We use adaptive optics (AO) techniques to manipulate the ocular aberrations and elucidate the effects of these ocular aberrations on contrast detection in a noisy background. The detectability of sine wave gratings at frequencies of 4, 8, and 16 circles per degree (cpd) was measured in a standard two-interval force-choice staircase procedure against backgrounds of various levels of white noise. The observer's ocular aberrations were either corrected with AO or left uncorrected. In low levels of external noise, contrast detection thresholds are always lowered by AO correction, whereas in high levels of external noise, they are generally elevated by AO correction. Higher levels of external noise are required to make this threshold elevation observable when signal spatial frequencies increase from 4 to 16 cpd. The linear-amplifier-model fit shows that mostly sampling efficiency and equivalent noise both decrease with AO correction. Our findings indicate that ocular aberrations could be beneficial for contrast detection in high-level noises. The implications of these findings are discussed.

  12. Using Aberrant Behaviors as Reinforcers for Autistic Children.

    Science.gov (United States)

    Charlop, Marjorie H.; And Others

    1990-01-01

    Three experiments assessed the efficacy of various reinforcers to increase correct task responding in a total of 10 autistic children, aged 6-9. Of the reinforcers used (stereotypy, delayed echolalia, perseverative behavior, and food), task performance was highest with opportunities to engage in aberrant behaviors, and lowest with edible…

  13. Analysis of the 'dilemma effect' in fifth-order deflection aberration

    International Nuclear Information System (INIS)

    Zhang Xiaobing; Yin Hanchun; Lei Wei; Xue Kunxing; Tong Linsu

    1999-01-01

    In this paper, the coma of the fifth-order aberration at a large deflection angle has been analyzed by using multipole field theory. The dilemma effect exists in the comas of fifth-order aberration. The dilemma effect, whose value D r is constant and independent of the 10-pole field, is the linear combination of coma aberrations. The coma of the fifth-order aberration is corrected by adjusting the 10-pole field distribution when D r is zero or small. The factors that influence the dilemma effect have been calculated and analyzed

  14. Optimization of transmission-scan time for the FixER method: a MR-based PET attenuation correction with a weak fixed-position external radiation source

    Energy Technology Data Exchange (ETDEWEB)

    Kawaguchi, Hiroshi; Hirano, Yoshiyuki; Kershaw, Jeff; Yoshida, Eiji [Molecular Imaging Center, National Institute of Radiological Sciences, Chiba (Japan); Shiraishi, Takahiro [Molecular Imaging Center, National Institute of Radiological Sciences, Chiba (Japan); Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, Chiba (Japan); Suga, Mikio [Molecular Imaging Center, National Institute of Radiological Sciences, Chiba (Japan); Center for Frontier Medical Engineering, Chiba University (Japan); Obata, Takayuki [Molecular Imaging Center, National Institute of Radiological Sciences, Chiba (Japan); Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, Chiba (Japan); Ito, Hiroshi; Yamaya, Taiga [Molecular Imaging Center, National Institute of Radiological Sciences, Chiba (Japan)

    2014-07-29

    In recent work, we proposed an MRI-based attenuation-coefficient (μ-value) estimation method that uses a weak fixed-position external radiation source to construct an attenuation map for PET/MRI. In this presentation we refer to this method as FixER, and perform a series of simulations to investigate the duration of the transmission scan required to accurately estimate μ-values.

  15. Optimization of transmission-scan time for the FixER method: a MR-based PET attenuation correction with a weak fixed-position external radiation source

    International Nuclear Information System (INIS)

    Kawaguchi, Hiroshi; Hirano, Yoshiyuki; Kershaw, Jeff; Yoshida, Eiji; Shiraishi, Takahiro; Suga, Mikio; Obata, Takayuki; Ito, Hiroshi; Yamaya, Taiga

    2014-01-01

    In recent work, we proposed an MRI-based attenuation-coefficient (μ-value) estimation method that uses a weak fixed-position external radiation source to construct an attenuation map for PET/MRI. In this presentation we refer to this method as FixER, and perform a series of simulations to investigate the duration of the transmission scan required to accurately estimate μ-values.

  16. Measurement of eye aberrations in a speckle field

    International Nuclear Information System (INIS)

    Larichev, A V; Ivanov, P V; Iroshnikov, N G; Shmalgauzen, V I

    2001-01-01

    The influence of speckles on the performance of a Shark-Hartmann wavefront sensor is investigated in the eye aberration studies. The dependence of the phase distortion measurement error on the characteristic speckle size is determined experimentally. Scanning of the reference source was used to suppress the speckle structure of the laser beam scattered by the retina. The technique developed by us made it possible to study the time dependence of the human eye aberrations with a resolution of 30 ms. (laser applications and other topics in quantum electronics)

  17. DNA Repair Defects and Chromosomal Aberrations

    Science.gov (United States)

    Hada, Megumi; George, K. A.; Huff, J. L.; Pluth, J. M.; Cucinotta, F. A.

    2009-01-01

    Yields of chromosome aberrations were assessed in cells deficient in DNA doublestrand break (DSB) repair, after exposure to acute or to low-dose-rate (0.018 Gy/hr) gamma rays or acute high LET iron nuclei. We studied several cell lines including fibroblasts deficient in ATM (ataxia telangiectasia mutated; product of the gene that is mutated in ataxia telangiectasia patients) or NBS (nibrin; product of the gene mutated in the Nijmegen breakage syndrome), and gliomablastoma cells that are proficient or lacking in DNA-dependent protein kinase (DNA-PK) activity. Chromosomes were analyzed using the fluorescence in situ hybridization (FISH) chromosome painting method in cells at the first division post irradiation, and chromosome aberrations were identified as either simple exchanges (translocations and dicentrics) or complex exchanges (involving >2 breaks in 2 or more chromosomes). Gamma irradiation induced greater yields of both simple and complex exchanges in the DSB repair-defective cells than in the normal cells. The quadratic dose-response terms for both simple and complex chromosome exchanges were significantly higher for the ATM- and NBS-deficient lines than for normal fibroblasts. However, in the NBS cells the linear dose-response term was significantly higher only for simple exchanges. The large increases in the quadratic dose-response terms in these repair-defective cell lines points the importance of the functions of ATM and NBS in chromatin modifications to facilitate correct DSB repair and minimize the formation of aberrations. The differences found between ATM- and NBS-deficient cells at low doses suggest that important questions should with regard to applying observations of radiation sensitivity at high dose to low-dose exposures. For aberrations induced by iron nuclei, regression models preferred purely linear dose responses for simple exchanges and quadratic dose responses for complex exchanges. Relative biological effectiveness (RBE) factors of all of

  18. Fifth-order canonical geometric aberration analysis of electrostatic round lenses

    CERN Document Server

    Liu Zhi Xiong

    2002-01-01

    In this paper the fifth-order canonical geometric aberration patterns are analyzed and a numerical example is given on the basis of the analytical expressions of fifth-order aberration coefficients derived in the present work. The fifth-order spherical aberration, astigmatism and field curvature, and distortion are similar to the third-order ones and the fifth-order coma is slightly different. Besides, there are two more aberrations which do not exist in the third-order aberration: they are peanut aberration and elliptical coma in accordance with their shapes. In the numerical example, by using a cross-check of the calculated coefficients with those computed through the differential algebraic method, it has been verified that all the expressions are correct and the computational results are reliable with high precision.

  19. Static telescope aberration measurement using lucky imaging techniques

    Science.gov (United States)

    López-Marrero, Marcos; Rodríguez-Ramos, Luis Fernando; Marichal-Hernández, José Gil; Rodríguez-Ramos, José Manuel

    2012-07-01

    A procedure has been developed to compute static aberrations once the telescope PSF has been measured with the lucky imaging technique, using a nearby star close to the object of interest as the point source to probe the optical system. This PSF is iteratively turned into a phase map at the pupil using the Gerchberg-Saxton algorithm and then converted to the appropriate actuation information for a deformable mirror having low actuator number but large stroke capability. The main advantage of this procedure is related with the capability of correcting static aberration at the specific pointing direction and without the need of a wavefront sensor.

  20. Theory of aberration fields for general optical systems with freeform surfaces.

    Science.gov (United States)

    Fuerschbach, Kyle; Rolland, Jannick P; Thompson, Kevin P

    2014-11-03

    This paper utilizes the framework of nodal aberration theory to describe the aberration field behavior that emerges in optical systems with freeform optical surfaces, particularly φ-polynomial surfaces, including Zernike polynomial surfaces, that lie anywhere in the optical system. If the freeform surface is located at the stop or pupil, the net aberration contribution of the freeform surface is field constant. As the freeform optical surface is displaced longitudinally away from the stop or pupil of the optical system, the net aberration contribution becomes field dependent. It is demonstrated that there are no new aberration types when describing the aberration fields that arise with the introduction of freeform optical surfaces. Significantly it is shown that the aberration fields that emerge with the inclusion of freeform surfaces in an optical system are exactly those that have been described by nodal aberration theory for tilted and decentered optical systems. The key contribution here lies in establishing the field dependence and nodal behavior of each freeform term that is essential knowledge for effective application to optical system design. With this development, the nodes that are distributed throughout the field of view for each aberration type can be anticipated and targeted during optimization for the correction or control of the aberrations in an optical system with freeform surfaces. This work does not place any symmetry constraints on the optical system, which could be packaged in a fully three dimensional geometry, without fold mirrors.

  1. Application of transmission scan-based attenuation compensation to scatter-corrected thallium-201 myocardial single-photon emission tomographic images

    International Nuclear Information System (INIS)

    Hashimoto, Jun; Kubo, Atsushi; Ogawa, Koichi; Ichihara, Takashi; Motomura, Nobutoku; Takayama, Takuzo; Iwanaga, Shiro; Mitamura, Hideo; Ogawa, Satoshi

    1998-01-01

    A practical method for scatter and attenuation compensation was employed in thallium-201 myocardial single-photon emission tomography (SPET or ECT) with the triple-energy-window (TEW) technique and an iterative attenuation correction method by using a measured attenuation map. The map was reconstructed from technetium-99m transmission CT (TCT) data. A dual-headed SPET gamma camera system equipped with parallel-hole collimators was used for ECT/TCT data acquisition and a new type of external source named ''sheet line source'' was designed for TCT data acquisition. This sheet line source was composed of a narrow long fluoroplastic tube embedded in a rectangular acrylic board. After injection of 99m Tc solution into the tube by an automatic injector, the board was attached in front of the collimator surface of one of the two detectors. After acquiring emission and transmission data separately or simultaneously, we eliminated scattered photons in the transmission and emission data with the TEW method, and reconstructed both images. Then, the effect of attenuation in the scatter-corrected ECT images was compensated with Chang's iterative method by using measured attenuation maps. Our method was validated by several phantom studies and clinical cardiac studies. The method offered improved homogeneity in distribution of myocardial activity and accurate measurements of myocardial tracer uptake. We conclude that the above correction method is feasible because a new type of 99m Tc external source may not produce truncation in TCT images and is cost-effective and easy to prepare in clinical situations. (orig.)

  2. Absolute determination of thyroid activity from profile scans. Description of a correction method for extra-thyroidal activity of the neck. , pt. 2

    International Nuclear Information System (INIS)

    Damme, K.J. van

    1977-01-01

    An absolute method to measure the uptake of radioactive iodide by the thyroid by making a profile scan across the thyroid region with a slit-collimated detector is described. It is well known that the extra-thyroidal activity (ETA) in the neck may constitute a severe hindrance to measure the uptake accurately, especially in cases of hypothyroidism and often during the first few hours after the administration of the traces dose (e.g. orally 0.5 μCiNa 131 I). The author's approach to the problem is presented. A practical application of the method is discussed in extenso. A comparative evaluation of the usability of 123 I and 131 I as least-burdening radionuclides for child patients is given at the end

  3. Fiducial marker-based correction for involuntary motion in weight-bearing C-arm CT scanning of knees. Part I. Numerical model-based optimization.

    Science.gov (United States)

    Choi, Jang-Hwan; Fahrig, Rebecca; Keil, Andreas; Besier, Thor F; Pal, Saikat; McWalter, Emily J; Beaupré, Gary S; Maier, Andreas

    2013-09-01

    Human subjects in standing positions are apt to show much more involuntary motion than in supine positions. The authors aimed to simulate a complicated realistic lower body movement using the four-dimensional (4D) digital extended cardiac-torso (XCAT) phantom. The authors also investigated fiducial marker-based motion compensation methods in two-dimensional (2D) and three-dimensional (3D) space. The level of involuntary movement-induced artifacts and image quality improvement were investigated after applying each method. An optical tracking system with eight cameras and seven retroreflective markers enabled us to track involuntary motion of the lower body of nine healthy subjects holding a squat position at 60° of flexion. The XCAT-based knee model was developed using the 4D XCAT phantom and the optical tracking data acquired at 120 Hz. The authors divided the lower body in the XCAT into six parts and applied unique affine transforms to each so that the motion (6 degrees of freedom) could be synchronized with the optical markers' location at each time frame. The control points of the XCAT were tessellated into triangles and 248 projection images were created based on intersections of each ray and monochromatic absorption. The tracking data sets with the largest motion (Subject 2) and the smallest motion (Subject 5) among the nine data sets were used to animate the XCAT knee model. The authors defined eight skin control points well distributed around the knees as pseudo-fiducial markers which functioned as a reference in motion correction. Motion compensation was done in the following ways: (1) simple projection shifting in 2D, (2) deformable projection warping in 2D, and (3) rigid body warping in 3D. Graphics hardware accelerated filtered backprojection was implemented and combined with the three correction methods in order to speed up the simulation process. Correction fidelity was evaluated as a function of number of markers used (4-12) and marker distribution

  4. Eye aberration analysis with Zernike polynomials

    Science.gov (United States)

    Molebny, Vasyl V.; Chyzh, Igor H.; Sokurenko, Vyacheslav M.; Pallikaris, Ioannis G.; Naoumidis, Leonidas P.

    1998-06-01

    New horizons for accurate photorefractive sight correction, afforded by novel flying spot technologies, require adequate measurements of photorefractive properties of an eye. Proposed techniques of eye refraction mapping present results of measurements for finite number of points of eye aperture, requiring to approximate these data by 3D surface. A technique of wave front approximation with Zernike polynomials is described, using optimization of the number of polynomial coefficients. Criterion of optimization is the nearest proximity of the resulted continuous surface to the values calculated for given discrete points. Methodology includes statistical evaluation of minimal root mean square deviation (RMSD) of transverse aberrations, in particular, varying consecutively the values of maximal coefficient indices of Zernike polynomials, recalculating the coefficients, and computing the value of RMSD. Optimization is finished at minimal value of RMSD. Formulas are given for computing ametropia, size of the spot of light on retina, caused by spherical aberration, coma, and astigmatism. Results are illustrated by experimental data, that could be of interest for other applications, where detailed evaluation of eye parameters is needed.

  5. The Art of Optical Aberrations

    Science.gov (United States)

    Wylde, Clarissa Eileen Kenney

    Art and optics are inseparable. Though seemingly opposite disciplines, the combination of art and optics has significantly impacted both culture and science as they are now known. As history has run its course, in the sciences, arts, and their fruitful combinations, optical aberrations have proved to be a problematic hindrance to progress. In an effort to eradicate aberrations the simple beauty of these aberrational forms has been labeled as undesirable and discarded. Here, rather than approach aberrations as erroneous, these beautiful forms are elevated to be the photographic subject in a new body of work, On the Bright Side. Though many recording methods could be utilized, this work was composed on classic, medium-format, photographic film using white-light, Michelson interferometry. The resulting images are both a representation of the true light rays that interacted on the distorted mirror surfaces (data) and the artist's compositional eye for what parts of the interferogram are chosen and displayed. A detailed description of the captivating interdisciplinary procedure is documented and presented alongside the final artwork, CCD digital reference images, and deformable mirror contour maps. This alluring marriage between the arts and sciences opens up a heretofore minimally explored aspect of the inextricable art-optics connection. It additionally provides a fascinating new conversation on the importance of light and optics in photographic composition.

  6. Seamless stitching of tile scan microscope images.

    Science.gov (United States)

    Legesse, F B; Chernavskaia, O; Heuke, S; Bocklitz, T; Meyer, T; Popp, J; Heintzmann, R

    2015-06-01

    For diagnostic purposes, optical imaging techniques need to obtain high-resolution images of extended biological specimens in reasonable time. The field of view of an objective lens, however, is often smaller than the sample size. To image the whole sample, laser scanning microscopes acquire tile scans that are stitched into larger mosaics. The appearance of such image mosaics is affected by visible edge artefacts that arise from various optical aberrations which manifest in grey level jumps across tile boundaries. In this contribution, a technique for stitching tiles into a seamless mosaic is presented. The stitching algorithm operates by equilibrating neighbouring edges and forcing the brightness at corners to a common value. The corrected image mosaics appear to be free from stitching artefacts and are, therefore, suited for further image analysis procedures. The contribution presents a novel method to seamlessly stitch tiles captured by a laser scanning microscope into a large mosaic. The motivation for the work is the failure of currently existing methods for stitching nonlinear, multimodal images captured by our microscopic setups. Our method eliminates the visible edge artefacts that appear between neighbouring tiles by taking into account the overall illumination differences among tiles in such mosaics. The algorithm first corrects the nonuniform brightness that exists within each of the tiles. It then compensates for grey level differences across tile boundaries by equilibrating neighbouring edges and forcing the brightness at the corners to a common value. After these artefacts have been removed further image analysis procedures can be applied on the microscopic images. Even though the solution presented here is tailored for the aforementioned specific case, it could be easily adapted to other contexts where image tiles are assembled into mosaics such as in astronomical or satellite photos. © 2015 The Authors Journal of Microscopy © 2015 Royal

  7. Theoretical estimates of spherical and chromatic aberration in photoemission electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Fitzgerald, J.P.S., E-mail: fit@pdx.edu; Word, R.C.; Könenkamp, R.

    2016-01-15

    We present theoretical estimates of the mean coefficients of spherical and chromatic aberration for low energy photoemission electron microscopy (PEEM). Using simple analytic models, we find that the aberration coefficients depend primarily on the difference between the photon energy and the photoemission threshold, as expected. However, the shape of the photoelectron spectral distribution impacts the coefficients by up to 30%. These estimates should allow more precise correction of aberration in PEEM in experimental situations where the aberration coefficients and precise electron energy distribution cannot be readily measured. - Highlights: • Spherical and chromatic aberration coefficients of the accelerating field in PEEM. • Compact, analytic expressions for coefficients depending on two emission parameters. • Effect of an aperture stop on the distribution is also considered.

  8. Nuclear Scans

    Science.gov (United States)

    Nuclear scans use radioactive substances to see structures and functions inside your body. They use a special ... images. Most scans take 20 to 45 minutes. Nuclear scans can help doctors diagnose many conditions, including ...

  9. Limitations of ZAF correction factors in the determination of calcium/phosphorus ratios: Important forensic science considerations relevant to the analysis of bone fragments using scanning electron microscopy and energy-dispersive x-ray microanalysis

    International Nuclear Information System (INIS)

    Payne, C.M.; Cromey, D.W.

    1990-01-01

    A series of calcium phosphate standards having calcium/phosphorus (Ca/P) molar ratios of 0.50, 1.00, 1.50, and 1.67, respectively, was prepared for bulk specimen analysis using scanning electron microscopy (SEM) and energy-dispersive X-ray microanalysis (EDXA). The standards were mounted on carbon planchettes as either pure crystals or crystals embedded in epoxy resin. Ten different samples of each embedded and non-embedded standard were analyzed in a JEOL 100 CX electron microscope interfaced with a Kevex 8000 EDXA system using a lithium-drifted silicon detector and a multichannel analyzer. The Ca/P ratios were determined by calculating both net peak intensities without matrix corrections and atomic kappa-ratios using the MAGIC V computer program with ZAF correction factors for quantitative analysis. There was such extensive absorption of phosphorus X-rays in standards embedded in an epoxy matrix that the observed Ca/P ratios were statistically compatible with four different standards ranging in theoretical Ca/P ratios from 1.0 to 1.67. Although the non-embedded crystals showed a greater separation in the Ca/P ratios, both methods of preparation produced serious flaws in analysis. Direct application of the discovery of this caveat to the identification of suspected bone fragments for forensic science purposes is discussed

  10. Freeform aberrations in phase space: an example.

    Science.gov (United States)

    Babington, James

    2017-06-01

    We consider how optical propagation and aberrations of freeform systems can be formulated in phase space. As an example system, a freeform prism is analyzed and discussed. Symmetry considerations and their group theory descriptions are given some importance. Numerical aberrations are also highlighted and put into the context of the underlying aberration theory.

  11. Mirror-based broadband scanner with minimized aberration

    Science.gov (United States)

    Yu, Jiun-Yann; Tzeng, Yu-Yi; Huang, Chen-Han; Chui, Hsiang-Chen; Chu, Shi-Wei

    2009-02-01

    To obtain specific biochemical information in optical scanning microscopy, labeling technique is routinely required. Instead of the complex and invasive sample preparation procedures, incorporating spectral acquisition, which commonly requires a broadband light source, provides another mechanism to enhance molecular contrast. But most current optical scanning system is lens-based and thus the spectral bandwidth is limited to several hundred nanometers due to anti-reflection coating and chromatic aberration. The spectral range of interest in biological research covers ultraviolet to infrared. For example, the absorption peak of water falls around 3 μm, while most proteins exhibit absorption in the UV-visible regime. For imaging purpose, the transmission window of skin and cerebral tissues fall around 1300 and 1800 nm, respectively. Therefore, to extend the spectral bandwidth of an optical scanning system from visible to mid-infrared, we propose a system composed of metallic coated mirrors. A common issue in such a mirror-based system is aberrations induced by oblique incidence. We propose to compensate astigmatism by exchanging the sagittal and tangential planes of the converging spherical mirrors in the scanning system. With the aid of an optical design software, we build a diffraction-limited broadband scanning system with wavefront flatness better than λ/4 at focal plane. Combined with a mirror-based objective this microscopic system will exhibit full spectral capability and will be useful in microscopic imaging and therapeutic applications.

  12. Three-dimensional ophthalmic optical coherence tomography with a refraction correction algorithm

    Science.gov (United States)

    Zawadzki, Robert J.; Leisser, Christoph; Leitgeb, Rainer; Pircher, Michael; Fercher, Adolf F.

    2003-10-01

    We built an optical coherence tomography (OCT) system with a rapid scanning optical delay (RSOD) line, which allows probing full axial eye length. The system produces Three-dimensional (3D) data sets that are used to generate 3D tomograms of the model eye. The raw tomographic data were processed by an algorithm, which is based on Snell"s law to correct the interface positions. The Zernike polynomials representation of the interfaces allows quantitative wave aberration measurements. 3D images of our results are presented to illustrate the capabilities of the system and the algorithm performance. The system allows us to measure intra-ocular distances.

  13. On- and off-eye spherical aberration of soft contact lenses and consequent changes of effective lens power.

    Science.gov (United States)

    Dietze, Holger H; Cox, Michael J

    2003-02-01

    Soft contact lenses produce a significant level of spherical aberration affecting their power on-eye. A simple model assuming that a thin soft contact lens aligns to the cornea predicts that these effects are similar on-eye and off-eye. The wavefront aberration for 17 eyes and 33 soft contact lenses on-eye was measured with a Shack-Hartmann wavefront sensor. The Zernike coefficients describing the on-eye spherical aberration of the soft contact lens were compared with off-eye ray-tracing results. Paraxial and effective lens power changes were determined. The model predicts the on-eye spherical aberration of soft contact lenses closely. The resulting power change for a +/- 7.00 D spherical soft contact lens is +/- 0.5 D for a 6-mm pupil diameter and +/- 0.1 D for a 3-mm pupil diameter. Power change is negligible for soft contact lenses corrected for off-eye spherical aberration. For thin soft contact lenses, the level of spherical aberration and the consequent power change is similar on-eye and off-eye. Soft contact lenses corrected for spherical aberration in air will be expected to be aberration-free on-eye and produce only negligibly small power changes. For soft contact lenses without aberration correction, for higher levels of ametropia and large pupils, the soft contact lens power should be determined with trial lenses with their power and p value similar to the prescribed lens. The benefit of soft contact lenses corrected for spherical aberration depends on the level of ocular spherical aberration.

  14. Pathophysiology of MDS: genomic aberrations.

    Science.gov (United States)

    Ichikawa, Motoshi

    2016-01-01

    Myelodysplastic syndromes (MDS) are characterized by clonal proliferation of hematopoietic stem/progenitor cells and their apoptosis, and show a propensity to progress to acute myelogenous leukemia (AML). Although MDS are recognized as neoplastic diseases caused by genomic aberrations of hematopoietic cells, the details of the genetic abnormalities underlying disease development have not as yet been fully elucidated due to difficulties in analyzing chromosomal abnormalities. Recent advances in comprehensive analyses of disease genomes including whole-genome sequencing technologies have revealed the genomic abnormalities in MDS. Surprisingly, gene mutations were found in approximately 80-90% of cases with MDS, and the novel mutations discovered with these technologies included previously unknown, MDS-specific, mutations such as those of the genes in the RNA-splicing machinery. It is anticipated that these recent studies will shed new light on the pathophysiology of MDS due to genomic aberrations.

  15. A high resolution chromosome image processor for study purposes, NIRS-1000:CHROMO STUDY, and algorithm developing to classify radiation induced aberrations.

    Science.gov (United States)

    Yamamoto, M; Hayata, I; Furuta, S

    1992-03-01

    Since 1989 we have promoted a project to develop an automated scoring system of radiation induced chromosome aberrations. As a first step, a high resolution image processing system for study purposes, NIRS-1000:CHROMO STUDY, has been developed. It is composed of: (1) CHROMO MARKER whose main purpose is to mark on images to make image data base, (2) CHROMO ALGO whose purpose is algorithm development, and (3) METAPHASE RANKER whose purposes are metaphase finding and ranking with a high power objective lens. However, METAPHASE RANKER is presently under development. The system utilizes a high definition video system so as to realize the best spatial resolution that is achievable with an optical microscope using an objective lens (x 100, numerical aperture 1.4). The video camera has 1024 effective scan lines to realize 0.1 microns sampling on a specimen. The system resolution achieved on the hard copy is less than 0.3 microns on a specimen. A preliminary algorithm has been developed to classify the aberrations on the system using projection information of gray level. The preliminary test results on excellent 10 metaphases show that the correct classification ratio is 92.7%, that the detection rate of the aberrations is 83.3% and that the false positive rate is 6.1%.

  16. Correlations between corneal and total wavefront aberrations

    Science.gov (United States)

    Mrochen, Michael; Jankov, Mirko; Bueeler, Michael; Seiler, Theo

    2002-06-01

    Purpose: Corneal topography data expressed as corneal aberrations are frequently used to report corneal laser surgery results. However, the optical image quality at the retina depends on all optical elements of the eye such as the human lens. Thus, the aim of this study was to investigate the correlations between the corneal and total wavefront aberrations and to discuss the importance of corneal aberrations for representing corneal laser surgery results. Methods: Thirty three eyes of 22 myopic subjects were measured with a corneal topography system and a Tschernig-type wavefront analyzer after the pupils were dilated to at least 6 mm in diameter. All measurements were centered with respect to the line of sight. Corneal and total wavefront aberrations were calculated up to the 6th Zernike order in the same reference plane. Results: Statistically significant correlations (p the corneal and total wavefront aberrations were found for the astigmatism (C3,C5) and all 3rd Zernike order coefficients such as coma (C7,C8). No statistically significant correlations were found for all 4th to 6th order Zernike coefficients except for the 5th order horizontal coma C18 (p equals 0.003). On average, all Zernike coefficients for the corneal aberrations were found to be larger compared to Zernike coefficients for the total wavefront aberrations. Conclusions: Corneal aberrations are only of limited use for representing the optical quality of the human eye after corneal laser surgery. This is due to the lack of correlation between corneal and total wavefront aberrations in most of the higher order aberrations. Besides this, the data present in this study yield towards an aberration balancing between corneal aberrations and the optical elements within the eye that reduces the aberration from the cornea by a certain degree. Consequently, ideal customized ablations have to take both, corneal and total wavefront aberrations, into consideration.

  17. Renal scan

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/003790.htm Renal scan To use the sharing features on this ... anaphylaxis . Alternative Names Renogram; Kidney scan Images Kidney anatomy Kidney - blood and urine flow References Chernecky CC, ...

  18. CT Scan

    Science.gov (United States)

    ... disease, lung nodules and liver masses Monitor the effectiveness of certain treatments, such as cancer treatment Detect ... scan done in a hospital or an outpatient facility. CT scans are painless and, with newer machines, ...

  19. Design of a Compact, Bimorph Deformable Mirror-Based Adaptive Optics Scanning Laser Ophthalmoscope.

    Science.gov (United States)

    He, Yi; Deng, Guohua; Wei, Ling; Li, Xiqi; Yang, Jinsheng; Shi, Guohua; Zhang, Yudong

    2016-01-01

    We have designed, constructed and tested an adaptive optics scanning laser ophthalmoscope (AOSLO) using a bimorph mirror. The simulated AOSLO system achieves diffraction-limited criterion through all the raster scanning fields (6.4 mm pupil, 3° × 3° on pupil). The bimorph mirror-based AOSLO corrected ocular aberrations in model eyes to less than 0.1 μm RMS wavefront error with a closed-loop bandwidth of a few Hz. Facilitated with a bimorph mirror at a stroke of ±15 μm with 35 elements and an aperture of 20 mm, the new AOSLO system has a size only half that of the first-generation AOSLO system. The significant increase in stroke allows for large ocular aberrations such as defocus in the range of ±600° and astigmatism in the range of ±200°, thereby fully exploiting the AO correcting capabilities for diseased human eyes in the future.

  20. Measurement of specimen-induced aberrations of biological samples using phase stepping interferometry.

    Science.gov (United States)

    Schwertner, M; Booth, M J; Neil, M A A; Wilson, T

    2004-01-01

    Confocal or multiphoton microscopes, which deliver optical sections and three-dimensional (3D) images of thick specimens, are widely used in biology. These techniques, however, are sensitive to aberrations that may originate from the refractive index structure of the specimen itself. The aberrations cause reduced signal intensity and the 3D resolution of the instrument is compromised. It has been suggested to correct for aberrations in confocal microscopes using adaptive optics. In order to define the design specifications for such adaptive optics systems, one has to know the amount of aberrations present for typical applications such as with biological samples. We have built a phase stepping interferometer microscope that directly measures the aberration of the wavefront. The modal content of the wavefront is extracted by employing Zernike mode decomposition. Results for typical biological specimens are presented. It was found for all samples investigated that higher order Zernike modes give only a small contribution to the overall aberration. Therefore, these higher order modes can be neglected in future adaptive optics sensing and correction schemes implemented into confocal or multiphoton microscopes, leading to more efficient designs.

  1. Automatic phase aberration compensation for digital holographic microscopy based on deep learning background detection.

    Science.gov (United States)

    Nguyen, Thanh; Bui, Vy; Lam, Van; Raub, Christopher B; Chang, Lin-Ching; Nehmetallah, George

    2017-06-26

    We propose a fully automatic technique to obtain aberration free quantitative phase imaging in digital holographic microscopy (DHM) based on deep learning. The traditional DHM solves the phase aberration compensation problem by manually detecting the background for quantitative measurement. This would be a drawback in real time implementation and for dynamic processes such as cell migration phenomena. A recent automatic aberration compensation approach using principle component analysis (PCA) in DHM avoids human intervention regardless of the cells' motion. However, it corrects spherical/elliptical aberration only and disregards the higher order aberrations. Traditional image segmentation techniques can be employed to spatially detect cell locations. Ideally, automatic image segmentation techniques make real time measurement possible. However, existing automatic unsupervised segmentation techniques have poor performance when applied to DHM phase images because of aberrations and speckle noise. In this paper, we propose a novel method that combines a supervised deep learning technique with convolutional neural network (CNN) and Zernike polynomial fitting (ZPF). The deep learning CNN is implemented to perform automatic background region detection that allows for ZPF to compute the self-conjugated phase to compensate for most aberrations.

  2. Chromosomal aberrations in ore miners of Slovakia

    International Nuclear Information System (INIS)

    Beno, M.; Vladar, M.; Nikodemova, D.; Vicanova, M.; Durcik, M.

    1998-01-01

    A pilot study was performed in which the incidence of chromosomal aberrations in lymphocytes of miners in ore mines located in Central Slovakia was monitored and related to lifetime underground radon exposure and to lifetime smoking. The conclusions drawn from the results of the study were as follows: the counts of chromosomal aberrations in lymphocytes of miners were significantly higher than in an age matched control group of white-collar staff; the higher counts of chromosomal aberrations could be ascribed to underground exposure of miners and to smoking; a dependence of chromosomal aberration counts on the exposure to radon could not be assessed. (A.K.)

  3. Scanning Tunneling Microscopy - image interpretation

    International Nuclear Information System (INIS)

    Maca, F.

    1998-01-01

    The basic ideas of image interpretation in Scanning Tunneling Microscopy are presented using simple quantum-mechanical models and supplied with examples of successful application. The importance is stressed of a correct interpretation of this brilliant experimental surface technique

  4. Possible mechanisms of chromosome aberrations. 2. Formation of aberrations after UV-irradiation

    International Nuclear Information System (INIS)

    Lebedeva, L.I.

    1982-01-01

    One of mechanisms of chromosome aberrations after UV-radiation of animal cells initiated by thymine dimerization from different dna threads (by cross joints) and finished in mitosis metaphase is discussed. The model of aberration formation, taking a count of peculiarities of chromosome ansate structure and predicting the important role of chromosome isolation during mitosis in realization of structural aberrations, is suggested. An attempt to present aberration formation under conditions of exact repair is the distinguishing feature of the model

  5. Effect of methods of myopia correction on visual acuity, contrast sensitivity, and depth of focus

    NARCIS (Netherlands)

    Nio, YK; Jansonius, NM; Wijdh, RHJ; Beekhuis, WH; Worst, JGF; Noorby, S; Kooijman, AC

    Purpose. To psychophysically measure spherical and irregular aberrations in patients with various types of myopia correction. Setting: Laboratory of Experimental Ophthalmology, University of Groningen, Groningen, The Netherlands. Methods: Three groups of patients with low myopia correction

  6. Nodal aberration theory applied to freeform surfaces

    Science.gov (United States)

    Fuerschbach, Kyle; Rolland, Jannick P.; Thompson, Kevin P.

    2014-12-01

    When new three-dimensional packages are developed for imaging optical systems, the rotational symmetry of the optical system is often broken, changing its imaging behavior and making the optical performance worse. A method to restore the performance is to use freeform optical surfaces that compensate directly the aberrations introduced from tilting and decentering the optical surfaces. In order to effectively optimize the shape of a freeform surface to restore optical functionality, it is helpful to understand the aberration effect the surface may induce. Using nodal aberration theory the aberration fields induced by a freeform surface in an optical system are explored. These theoretical predications are experimentally validated with the design and implementation of an aberration generating telescope.

  7. Cooperative scans

    NARCIS (Netherlands)

    M. Zukowski (Marcin); P.A. Boncz (Peter); M.L. Kersten (Martin)

    2004-01-01

    textabstractData mining, information retrieval and other application areas exhibit a query load with multiple concurrent queries touching a large fraction of a relation. This leads to individual query plans based on a table scan or large index scan. The implementation of this access path in most

  8. Understanding the structure of nanocatalysts with high resolution scanning/transmission electron microscopy

    International Nuclear Information System (INIS)

    Francis, L D; Rivas, J; José-Yacamán, M

    2014-01-01

    Nanomaterials including nanoparticles, nanowires and nanotubes play an important role in heterogeneous catalysis. Thanks to the rapid improvement of the electron microscopic techniques and with the advent of aberration corrected electron microscopy as well as theoretical methodologies, the potential effects induced by nanocatalysts are better understood than before by unravelling their atomic structure. A brief introduction to advanced electron microscopic techniques namely aberration corrected scanning transmission electron microscopy (Cs-STEM) is presented and subsequently two examples of nanocatalysts are considered in the present review. The first example will focus on the study of bimetallic/core-shell nanoalloys. In heterogeneous catalysis, catalysts containing two or more metals might show significantly different catalytic properties compared to the parent metals and thus are widely utilized in several catalytic reactions. Atom-by-atom insights of the nanoalloy based catalysts ex: Au-Pd will be described in the present review using a combination of advanced electron microscopic and spectroscopic techniques. A related example on the understanding of bimetallic clusters by HAADF-STEM will also be presented in addition to nanoparticles. In the second case understanding the structure of transition metal chalcogenide based nanocatalysts by HRTEM and aberration corrected STEM, for the case of MoS 2 will be discussed. MoS 2 -based catalysts serve as model catalysts and are employed in the hydrodesulphurisations (HDS) reactions in the removal of sulphur from gasoline and related petrochemical products. They have been studied in various forms including nanowires, nanotubes and nanoplates. Their structure, atomic insights and as a consequence elucidation of their corresponding catalytic activity are thus important

  9. Chromosome painting analysis of radiation-induced aberrant cell clones in the mouse

    International Nuclear Information System (INIS)

    Spruill, M.D.; Nath, J.; Tucker, J.D.

    1997-01-01

    In a study of the persistence of radiation-induced translocations over the life span of the mouse, we observed a number of clonal cells in peripheral blood lymphocytes. The presence of clones caused the mean frequency of aberrations at various time points to be elevated which interfered with biodosimetry. For this reason, we have corrected our data for the presence of clones. Mice were given an acute dose of 0, 1, 2, 3 or 4 Gy 137 Cs at 8 weeks of age. Aberrations were measured by painting chromosomes 2 and 8 and cells were examined for clones at 3 months and every 3 months thereafter until 21 months. Clones were identified by comparing the color photographic slides of all abnormal cells from each animal. Determination of clonality was made on the basis of similar breakpoint locations or the presence of other identifying characteristics such as unusual aberrations. To correct the frequency of translocations for the presence of clones, each clone, regardless of how many cells it contained, was counted only once. This reflects the original aberration frequency since each clone originated as only one cell. Among mice exposed to 4 Gy, the mean frequencies of aberrant cell clones ranged from 3-29% of the total number of metaphase cells scored with the highest frequency being 1 year post exposure. 32-70% of reciprocal and 19-92% of non-reciprocal translocations were clonal. A dose response relationship for clones was evident until 21 months when the unexposed animals exhibited a mean frequency of aberrant cell clones >10% of the total number of cells scored. Almost 75% of reciprocal and 95% of non-reciprocal translocations in these unexposed control animals were of clonal origin. Correction for clonal expansion greatly reduced the means and their standard errors at most time points where clonal expansion was prevalent. The biodosimetry was much improved suggesting that correction is beneficial in long-term studies

  10. [Monochromatic aberration in accommodation. Dynamic wavefront analysis].

    Science.gov (United States)

    Fritzsch, M; Dawczynski, J; Jurkutat, S; Vollandt, R; Strobel, J

    2011-06-01

    Monochromatic aberrations may influence the visual acuity of the eye. They are not stable and can be affected by different factors. The subject of the following paper is the dynamic investigation of the changes in wavefront aberration with accommodation. Dynamic measurement of higher and lower order aberrations was performed with a WASCA Wavefront Analyzer (Carl-Zeiss-Meditec) and a specially constructed target device for aligning objects in far and near distances on 25 subjects aged from 15 to 27 years old. Wavefront aberrations showed some significant changes in accommodation. In addition to the characteristic sphere reaction accompanying miosis and changes in horizontal prism (Z(1) (1)) in the sense of a convergence movement of the eyeball also occurred. Furthermore defocus rose (Z(2) (0)) and astigmatism (Z(2) (-2)) changed. In higher-order aberrations a decrease in coma-like Zernike polynomials (Z(3) (-1), Z(3) (1)) was found. The most obvious change appeared in spherical aberration (Z(4) (0)) which increased and changed from positive to negative. In addition the secondary astigmatism (Z(4) (-2)) and quadrafoil (Z(4) (4)) rise also increased. The total root mean square (RMS), as well as the higher-order aberrations (RMS-HO) significantly increased in accommodation which is associated with a theoretical reduction of visual acuity. An analysis of the influence of pupil size on aberrations showed significant increases in defocus, spherical aberration, quadrafoil, RMS and RMS HO by increasing pupil diameter. By accommodation-associated miosis, the growing aberrations are partially compensated by focusing on near objects. Temporal analysis of the accommodation process with dynamic wavefront analysis revealed significant delays in pupil response and changing of prism in relation to the sphere reaction. In accommodation to near objects a discrete time ahead of third order aberrations in relation to the sphere response was found. Using dynamic wavefront measurement

  11. Radionuclide scanning

    International Nuclear Information System (INIS)

    Shapiro, B.

    1986-01-01

    Radionuclide scanning is the production of images of normal and diseased tissues and organs by means of the gamma-ray emissions from radiopharmaceutical agents having specific distributions in the body. The gamma rays are detected at the body surface by a variety of instruments that convert the invisible rays into visible patterns representing the distribution of the radionuclide in the body. The patterns, or images, obtained can be interpreted to provide or to aid diagnoses, to follow the course of disease, and to monitor the management of various illnesses. Scanning is a sensitive technique, but its specificity may be low when interpreted alone. To be used most successfully, radionuclide scanning must be interpreted in conjunction with other techniques, such as bone radiographs with bone scans, chest radiographs with lung scans, and ultrasonic studies with thyroid scans. Interpretation is also enhanced by providing pertinent clinical information because the distribution of radiopharmaceutical agents can be altered by drugs and by various procedures besides physiologic and pathologic conditions. Discussion of the patient with the radionuclide scanning specialist prior to the study and review of the results with that specialist after the study are beneficial

  12. Population spherical aberration: associations with ametropia, age, corneal curvature, and image quality

    Directory of Open Access Journals (Sweden)

    Kingston AC

    2013-05-01

    Full Text Available Amanda C Kingston,1,2 Ian G Cox11Bausch + Lomb, Rochester, NY, USA; 2Department of Biomedical Engineering, University of Rochester, Rochester, NY, USAPurpose: The aim of this analysis was to determine the total ocular wavefront aberration values of a large phakic population of physiologically normal, ametropic eyes, gathered under the same clinical protocol using the same diagnostic wavefront sensor.Materials and methods: Studies were conducted at multiple sites in Asia, North America, Europe, and Australia. A Bausch + Lomb Zywave II Wavefront Aberrometer (Rochester, NY, USA was used to measure the lower and higher order aberrations of each eye. Data analysis was conducted using linear regression analysis to determine the relationship between total spherical aberration, ametropia, age, corneal curvature, and image quality.Results: Linear regression analysis showed no correlation (r = 0.0207, P = 0.4874 between degree of ametropia and the amount of spherical aberration. There was also no correlation when the population was stratified into myopic and hyperopic refractive groups (rm = 0.0529, Pm = 0.0804 and rh = 0.1572, Ph = 0.2754. There was a statistically significant and weak positive correlation (r = 0.1962, P < 0.001 between age and the amount of spherical aberration measured in the eye; spherical aberration became more positive with increasing age. Also, there was a statistically significant and moderately positive correlation (r = 0.3611, P < 0.001 with steepness of corneal curvature; spherical aberration became more positive with increasing power of the anterior corneal surface. Assessment of image quality using optical design software (Zemax™, Bellevue, WA, USA showed that there was an overall benefit in correcting the average spherical aberration of this population.Conclusion: Analysis of this dataset provides insights into the inherent spherical aberration of a typical phakic, pre-presbyopic, population and provides the ability to

  13. Flow cytogenetics: progress toward chromosomal aberration detection

    International Nuclear Information System (INIS)

    Carrano, A.V.; Gray, J.W.; Van Dilla, M.A.

    1977-01-01

    Using clonal derivatives of the Chinese hamster M3-1 cell line, we demonstrate the potential of flow systems to karyotype homogeneous aberrations (aberrations which are identical and present in every cell) and to detect heterogeneous aberrations (aberrations which occur randomly in a population and are not identical in every cell). Flow cytometry (FCM) of ethidium bromide stained isolated chromosomes from clone 650A of the M3-1 cells distinguishes nine chromosome types from the fourteen present in the actual karyotype. X-irradiation of this parent 650A clone produced two sub-clones with an altered flow karyotype, that is, their FCM distributions were characterized by the addition of new peaks and alterations in area under existing peaks. From the relative DNA content and area for each peak, as determined by computer analysis, we predicted that each clone had undergone a reciprocal translocation involving chromosomes from two peaks. This prediction was confirmed by Giemsa-banding the metaphase cells. Heterogeneous aberrations are reflected in the flow karyotype as an increase in background, that is, an increase in area underlying the chromosome peaks. This increase is dose dependent but, as yet, the sample variability has been too large for quantitative analysis. Flow sorting of the valleys between chromosome peaks produces enriched fractions of aberrant chromosomes for visual analysis. These approaches are potentially applicable to the analysis of chromsomal aberrations induced by environmental contaminants

  14. Diagnostic radiation and chromosome aberrations

    International Nuclear Information System (INIS)

    Patil, S.R.; Hecht, F.; Lubs, H.A.; Kimberling, W.; Brown, J.; Gerald, P.S.; Summitt, R.L.

    1977-01-01

    Some evidence is presented suggesting that diagnostic X-rays may be important in the origin of a new chromosomal abnormality other than Down syndrome. Chromosome analyses have been carried out on 4342 children, seven or eight years old. Maternal diagnostic irradiation in the year before conception and up to third lunar month of the index pregnancy was recorded, before the chromosome study began, together with a large amount of family and clinical data. Information on X-ray exposure was supplied by the mothers, s o radiation dosage could not be estimated. 21 children (including a pair of twins and a pair of siblings) born to 19 mothers had chromosomal aberrations. The mothers of six children with inherited translocations, rearrangements and XYY karyotypes were excluded, and 3 (23%) of the remaining 13 mothers had received abdominal and pelvic X-ray exposures. In the whole sample, however, only 6% of the mothers had diagnostic irradiation. Two of these mothers, aged sixteen and twenty, gave birth to a child each with de-novo autosomal translocations, and the third mother, aged thirty-two, had a child with a complex mosaicism involving one X chromosome. Although the sample size of the mothers with chromosomally abnormal children is small, the results are significant. (U.K.)

  15. Diagnostic radiation and chromosome aberrations

    Energy Technology Data Exchange (ETDEWEB)

    Patil, S R; Hecht, F [Dept. of Pediatrics, Child Development and Rehabilitation Center, Univ. of Oregon Health Sciences Center, Portland, Oregon (USA); Lubs, H A; Kimberling, W; Brown, J; Gerald, P S; Summitt, R L

    1977-01-15

    Some evidence is presented suggesting that diagnostic X-rays may be important in the origin of a new chromosomal abnormality other than Down syndrome. Chromosome analyses have been carried out on 4342 children, seven or eight years old. Maternal diagnostic irradiation in the year before conception and up to third lunar month of the index pregnancy was recorded, before the chromosome study began, together with a large amount of family and clinical data. Information on X-ray exposure was supplied by the mothers, so radiation dosage could not be estimated. 21 children (including a pair of twins and a pair of siblings) born to 19 mothers had chromosomal aberrations. The mothers of six children with inherited translocations, rearrangements and XYY karyotypes were excluded, and 3 (23%) of the remaining 13 mothers had received abdominal and pelvic X-ray exposures. In the whole sample, however, only 6% of the mothers had diagnostic irradiation. Two of these mothers, aged sixteen and twenty, gave birth to a child each with de-novo autosomal translocations, and the third mother, aged thirty-two, had a child with a complex mosaicism involving one X chromosome. Although the sample size of the mothers with chromosomally abnormal children is small, the results are significant.

  16. Chromosome aberration assays in Allium

    Energy Technology Data Exchange (ETDEWEB)

    Grant, W.F.

    1982-01-01

    The common onion (Allium cepa) is an excellent plant for the assay of chromosome aberrations after chemical treatment. Other species of Allium (A. cepa var. proliferum, A. carinatum, A. fistulosum and A. sativum) have also been used but to a much lesser extent. Protocols have been given for using root tips from either bulbs or seeds of Allium cepa to study the cytological end-points, such as chromosome breaks and exchanges, which follow the testing of chemicals in somatic cells. It is considered that both mitotic and meiotic end-points should be used to a greater extent in assaying the cytogenetic effects of a chemical. From a literature survey, 148 chemicals are tabulated that have been assayed in 164 Allium tests for their clastogenic effect. Of the 164 assays which have been carried out, 75 are reported as giving a positive reaction, 49 positive and with a dose response, 1 positive and temperature-related, 9 borderline positive, and 30 negative; 76% of the chemicals gave a definite positive response. It is proposed that the Allium test be included among those tests routinely used for assessing chromosomal damage induced by chemicals.

  17. Aberrant regeneration of the third cranial nerve.

    Science.gov (United States)

    Shrestha, U D; Adhikari, S

    2012-01-01

    Aberrant regeneration of the third cranial nerve is most commonly due to its damage by trauma. A ten-month old child presented with the history of a fall from a four-storey building. She developed traumatic third nerve palsy and eventually the clinical features of aberrant regeneration of the third cranial nerve. The adduction of the eye improved over time. She was advised for patching for the strabismic amblyopia as well. Traumatic third nerve palsy may result in aberrant regeneration of the third cranial nerve. In younger patients, motility of the eye in different gazes may improve over time. © NEPjOPH.

  18. Transverse correlation vanishing due to phase aberrations

    CSIR Research Space (South Africa)

    Godin, T

    2011-06-01

    Full Text Available of the effects of each aberration on the ratio Sp ?? / , the following condition are imposed: 0max3max2max1 )()()( ??????? === . (9) It is assumed that the phase aberration is set in the beam-waist plane of radius mmW 5.10 = . Arbitrarily, the value... of max? is fixed to twice the incident beam width, 0max 2W=? , where the intensity is only 0.03% of the on-axis value. In the following we will express the aberration 0? in number of equivalent wavelengths given by the ratio )2/(00 pi...

  19. Color corrected Fresnel lens for solar concentration

    International Nuclear Information System (INIS)

    Kritchman, E.M.

    1979-01-01

    A new linear convex Fresnel lens with its groove side down is described. The design philosophy is similar to the highly concentrating two focal Fresnel lens but including a correction for chromatic aberration. A solar concentration ratio as high as 80 is achieved. For wide acceptance angles the concentration nears the theoretical maximum. (author)

  20. Comparison of monochromatic aberrations in young adults with different visual acuity and refractive errors.

    Science.gov (United States)

    Yazar, Seyhan; Hewitt, Alex W; Forward, Hannah; McKnight, Charlotte M; Tan, Alex; Mountain, Jenny A; Mackey, David A

    2014-03-01

    To compare the monochromatic aberrations in a large cohort of 20-year-old Australians with differing levels of visual acuity and explore the relationship between these aberrations and refractive error. Lions Eye Institute, Perth, Western Australia, Australia. Cross-sectional analysis of a population-based cohort. Monochromatic aberrations were measured using a Zywave II wavefront aberrometer with natural pupils in a dark room. The logMAR corrected distance visual acuity (CDVA) was measured monocularly under normal illumination. Cycloplegic autorefraction was also performed. The study enrolled 2039 eyes of 1040 participants. Data from 1007 right eyes were analyzed. The median CDVA and spherical equivalent were -0.06 logMAR (interquartile range [IQR], -0.10 to 0.00) and +0.25 diopters (D) (IQR, -0.38 to 0.63), respectively. The median 6.0 mm higher-order aberration (HOA) was 0.58 μm (IQR, 0.44 to 0.79). Coma-like aberrations and 3rd-, 4th-, and 5th-order HOAs were significantly different between subjects with a CDVA of -0.10 logMAR or better and those with a CDVA worse than -0.10 logMAR. Fourth-order aberrations Z(4,-4) (P=.024) and Z(4,-2) (P=.029) and 2nd-order aberration Z(2,0) (Peyes, emmetropic eyes, and hyperopic eyes. Subjects with higher myopia had slightly higher total HOAs. The HOAs in this population were marginally higher than previously reported values. The findings confirm there is a difference in monochromatic aberrations between different vision and refractive groups. Results in this study will benefit decision-making processes in the clinical setting. Copyright © 2014 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  1. Spherical aberration compensation method for long focal-length measurement based on Talbot interferometry

    Science.gov (United States)

    Luo, Yupeng; Huang, Xiao; Bai, Jian; Du, Juan; Liu, Qun; Luo, Yujie; Luo, Jia

    2017-08-01

    Large-aperture and long focal-length lens is widely used in high energy laser system. The method based on Talbot interferometry is a reliable method to measure the focal length of such elements. By employing divergent beam and two gratings of different periods, this method could realize full-aperture measurement, higher accuracy and better repeatability. However, it does not take into account the spherical aberration of the measured lens resulting in the moiré fringes bending, which will introduce measurement error. Furthermore, in long-focal measurement with divergent beam, this error is an important factor affecting the measurement accuracy. In this paper, we propose a new spherical aberration compensation method, which could significantly reduce the measurement error. Characterized by central-symmetric scanning window, the proposed method is based on the relationship between spherical aberration and the lens aperture. Angle data of moiré fringes in each scanning window is retrieved by Fourier analysis and statistically fitted to estimate a globally optimum value for spherical-aberration-free focal length calculation. Simulation and experiment have been carried out. Compared to the previous work, the proposed method is able to reduce the relative measurement error by 50%. The effect of scanning window size and shift step length on the results is also discussed.

  2. Attenuation correction for SPECT

    International Nuclear Information System (INIS)

    Hosoba, Minoru

    1986-01-01

    Attenuation correction is required for the reconstruction of a quantitative SPECT image. A new method for detecting body contours, which are important for the correction of tissue attenuation, is presented. The effect of body contours, detected by the newly developed method, on the reconstructed images was evaluated using various techniques for attenuation correction. The count rates in the specified region of interest in the phantom image by the Radial Post Correction (RPC) method, the Weighted Back Projection (WBP) method, Chang's method were strongly affected by the accuracy of the contours, as compared to those by Sorenson's method. To evaluate the effect of non-uniform attenuators on the cardiac SPECT, computer simulation experiments were performed using two types of models, the uniform attenuator model (UAM) and the non-uniform attenuator model (NUAM). The RPC method showed the lowest relative percent error (%ERROR) in UAM (11 %). However, 20 to 30 percent increase in %ERROR was observed for NUAM reconstructed with the RPC, WBP, and Chang's methods. Introducing an average attenuation coefficient (0.12/cm for Tc-99m and 0.14/cm for Tl-201) in the RPC method decreased %ERROR to the levels for UAM. Finally, a comparison between images, which were obtained by 180 deg and 360 deg scans and reconstructed from the RPC method, showed that the degree of the distortion of the contour of the simulated ventricles in the 180 deg scan was 15 % higher than that in the 360 deg scan. (Namekawa, K.)

  3. Measured attenuation correction methods

    International Nuclear Information System (INIS)

    Ostertag, H.; Kuebler, W.K.; Doll, J.; Lorenz, W.J.

    1989-01-01

    Accurate attenuation correction is a prerequisite for the determination of exact local radioactivity concentrations in positron emission tomography. Attenuation correction factors range from 4-5 in brain studies to 50-100 in whole body measurements. This report gives an overview of the different methods of determining the attenuation correction factors by transmission measurements using an external positron emitting source. The long-lived generator nuclide 68 Ge/ 68 Ga is commonly used for this purpose. The additional patient dose from the transmission source is usually a small fraction of the dose due to the subsequent emission measurement. Ring-shaped transmission sources as well as rotating point or line sources are employed in modern positron tomographs. By masking a rotating line or point source, random and scattered events in the transmission scans can be effectively suppressed. The problems of measured attenuation correction are discussed: Transmission/emission mismatch, random and scattered event contamination, counting statistics, transmission/emission scatter compensation, transmission scan after administration of activity to the patient. By using a double masking technique simultaneous emission and transmission scans become feasible. (orig.)

  4. An Image Processing Approach to Pre-compensation for Higher-Order Aberrations in the Eye

    Directory of Open Access Journals (Sweden)

    Miguel Alonso Jr

    2004-06-01

    Full Text Available Human beings rely heavily on vision for almost all of the tasks that are required in daily life. Because of this dependence on vision, humans with visual limitations, caused by genetic inheritance, disease, or age, will have difficulty in completing many of the tasks required of them. Some individuals with severe visual impairments, known as high-order aberrations, may have difficulty in interacting with computers, even when using a traditional means of visual correction (e.g., spectacles, contact lenses. This is, in part, because these correction mechanisms can only compensate for the most regular (low-order distortions or aberrations of the image in the eye. This paper presents an image processing approach that will pre-compensate the images displayed on the computer screen, so as to counter the effect of the eye's aberrations on the image. The characterization of the eye required to perform this customized pre-compensation is the eye's Point Spread Function (PSF. Ophthalmic instruments generically called "Wavefront Analyzers" can now measure this description of the eye's optical properties. The characterization provided by these instruments also includes the "higher-order aberration components" and could, therefore, lead to a more comprehensive vision correction than traditional mechanisms. This paper explains the theoretical foundation of the methods proposed and illustrates them with experiments involving the emulation of a known and constant PSF by interposing a lens in the field of view of normally sighted test subjects.

  5. Scanning table

    CERN Multimedia

    1960-01-01

    Before the invention of wire chambers, particles tracks were analysed on scanning tables like this one. Today, the process is electronic and much faster. Bubble chamber film - currently available - (links can be found below) was used for this analysis of the particle tracks.

  6. Scan Statistics

    CERN Document Server

    Glaz, Joseph

    2009-01-01

    Suitable for graduate students and researchers in applied probability and statistics, as well as for scientists in biology, computer science, pharmaceutical science and medicine, this title brings together a collection of chapters illustrating the depth and diversity of theory, methods and applications in the area of scan statistics.

  7. Geometric characteristics of aberrations of plane-symmetric optical systems

    International Nuclear Information System (INIS)

    Lu Lijun; Deng Zhiyong

    2009-01-01

    The geometric characteristics of aberrations of plane-symmetric optical systems are studied in detail with a wave-aberration theory. It is dealt with as an extension of the Seidel aberrations to realize a consistent aberration theory from axially symmetric to plane-symmetric systems. The aberration distribution is analyzed with the spot diagram of a ray and an aberration curve. Moreover, the root-mean-square value and the centroid of aberration distribution are discussed. The numerical results are obtained with the focusing optics of a toroidal mirror at grazing incidence.

  8. Surgical treatment of massive bleeding of a right aberrant subclavian artery after oesophageal stent removal

    Directory of Open Access Journals (Sweden)

    Michael Raum

    2018-06-01

    Full Text Available We report a case of a 9-year-old female who required surgical treatment and resuscitation after severe transoesophageal bleeding of a right aberrant subclavian artery (RASA. Bleeding of this RASA was caused by a mechanical irritation due to an oesophageal stent. The stent was placed weeks before to dilate the oesophagus after accidental ingestion of a caustic agent. Although conservative management of benign oesophageal stenosis in children is highly recommended, there are still some major complications to be considered. To avoid erosion of aberrant subclavian artery vascular rings and slings, as described in several case reports, these vessels should be excluded by computed tomography (CT or magnetic resonance imaging (MRI scans before placement of oesophageal stents. This case suggests that management of caustic ingestion in children is still a major challenge in paediatric surgical departments. Keywords: Paediatric surgery, Chemical Burn, Oesophageal stenosis, Oesophageal stenting, Vascular abnormalities, Right aberrant subclavian artery

  9. High resolution melting for mutation scanning of TP53 exons 5–8

    International Nuclear Information System (INIS)

    Krypuy, Michael; Dobrovic, Alexander; Ahmed, Ahmed Ashour; Etemadmoghadam, Dariush; Hyland, Sarah J; Australian Ovarian Cancer Study Group; Fazio, Anna de; Fox, Stephen B; Brenton, James D; Bowtell, David D

    2007-01-01

    p53 is commonly inactivated by mutations in the DNA-binding domain in a wide range of cancers. As mutant p53 often influences response to therapy, effective and rapid methods to scan for mutations in TP53 are likely to be of clinical value. We therefore evaluated the use of high resolution melting (HRM) as a rapid mutation scanning tool for TP53 in tumour samples. We designed PCR amplicons for HRM mutation scanning of TP53 exons 5 to 8 and tested them with DNA from cell lines hemizygous or homozygous for known mutations. We assessed the sensitivity of each PCR amplicon using dilutions of cell line DNA in normal wild-type DNA. We then performed a blinded assessment on ovarian tumour DNA samples that had been previously sequenced for mutations in TP53 to assess the sensitivity and positive predictive value of the HRM technique. We also performed HRM analysis on breast tumour DNA samples with unknown TP53 mutation status. One cell line mutation was not readily observed when exon 5 was amplified. As exon 5 contained multiple melting domains, we divided the exon into two amplicons for further screening. Sequence changes were also introduced into some of the primers to improve the melting characteristics of the amplicon. Aberrant HRM curves indicative of TP53 mutations were observed for each of the samples in the ovarian tumour DNA panel. Comparison of the HRM results with the sequencing results revealed that each mutation was detected by HRM in the correct exon. For the breast tumour panel, we detected seven aberrant melt profiles by HRM and subsequent sequencing confirmed the presence of these and no other mutations in the predicted exons. HRM is an effective technique for simple and rapid scanning of TP53 mutations that can markedly reduce the amount of sequencing required in mutational studies of TP53

  10. Measuring aberrations in the rat brain by coherence-gated wavefront sensing using a Linnik interferometer.

    Science.gov (United States)

    Wang, Jinyu; Léger, Jean-François; Binding, Jonas; Boccara, A Claude; Gigan, Sylvain; Bourdieu, Laurent

    2012-10-01

    Aberrations limit the resolution, signal intensity and achievable imaging depth in microscopy. Coherence-gated wavefront sensing (CGWS) allows the fast measurement of aberrations in scattering samples and therefore the implementation of adaptive corrections. However, CGWS has been demonstrated so far only in weakly scattering samples. We designed a new CGWS scheme based on a Linnik interferometer and a SLED light source, which is able to compensate dispersion automatically and can be implemented on any microscope. In the highly scattering rat brain tissue, where multiply scattered photons falling within the temporal gate of the CGWS can no longer be neglected, we have measured known defocus and spherical aberrations up to a depth of 400 µm.

  11. Frequencies of chromosome aberration on radiation workers

    International Nuclear Information System (INIS)

    Yanti Lusiyanti; Zubaidah Alatas

    2016-01-01

    Radiation exposure of the body can cause damage to the genetic material in cells (cytogenetic) in the form of changes in the structure or chromosomal aberrations in peripheral blood lymphocytes. Chromosomal aberrations can be unstable as dicentric and ring chromosomes, and is stable as translocation. Dicentric chromosome is the gold standard biomarker due to radiation exposure, and chromosome translocation is a biomarker for retrospective biodosimetry. The aim of this studi is to conduct examination of chromosomal aberrations in the radiation worker to determine the potential damage of cell that may arise due to occupational radiation exposure. The examination have been carried out on blood samples from 55 radiation workers in the range of 5-30 year of service. Chromosome aberration frequency measurement starts with blood sampling, culturing, harvesting, slide preparations, and lymphocyte chromosome staining with Giemsa and painting with Fluorescence In Situ Hybridization (FISH) technique. The results showed that chromosomal translocations are not found in blood samples radiation workers and dicentric chromosomes found only on 2 blood samples of radiation workers with a frequency of 0.001/cell. The frequency of chromosomal aberrations in the blood cells such workers within normal limits and this means that the workers have been implemented a radiation safety aspects very well. (author)

  12. Scanning holograms

    International Nuclear Information System (INIS)

    Natali, S.

    1984-01-01

    This chapter reports on the scanning of 1000 holograms taken in HOBC at CERN. Each hologram is triggered by an interaction in the chamber, the primary particles being pions at 340 GeV/c. The aim of the experiment is the study of charm production. The holograms, recorded on 50 mm film with the ''in line'' technique, can be analyzed by shining a parallel expanded laser beam through the film, obtaining immediately above it the real image of the chamber which can then be scanned and measured with a technique half way between emulsions and bubble chambers. The results indicate that holograms can be analyzed as quickly and reliably as in other visual techniques and that to them is open the same order of magnitude of large scale experiments

  13. Publisher Correction

    DEFF Research Database (Denmark)

    Turcot, Valérie; Lu, Yingchang; Highland, Heather M

    2018-01-01

    In the published version of this paper, the name of author Emanuele Di Angelantonio was misspelled. This error has now been corrected in the HTML and PDF versions of the article.......In the published version of this paper, the name of author Emanuele Di Angelantonio was misspelled. This error has now been corrected in the HTML and PDF versions of the article....

  14. Author Correction

    DEFF Research Database (Denmark)

    Grundle, D S; Löscher, C R; Krahmann, G

    2018-01-01

    A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has not been fixed in the paper.......A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has not been fixed in the paper....

  15. Effect of Spherical Aberration on the Optical Quality after Implantation of Two Different Aspherical Intraocular Lenses

    Directory of Open Access Journals (Sweden)

    Michael Lasta

    2017-01-01

    Full Text Available Purpose. To compare the effect of spherical aberration on optical quality in eyes with two different aspherical intraocular lenses. Methods. 120 eyes of 60 patients underwent phacoemulsification. In patients’ eyes, an aberration-free IOL (Aspira-aA; Human Optics or an aberration-correcting aspherical IOL (Tecnis ZCB00; Abott Medical Optics was randomly implanted. After surgery, contrast sensitivity and wavefront measurements as well as tilt and decentration measurements were performed. Results. Contrast sensitivity was significantly higher in eyes with Aspira lens under mesopic conditions with 12 cycles per degree (CPD and under photopic conditions with 18 CPD (p=0.02. Wavefront measurements showed a higher total spherical aberration with a minimal pupil size of 4 mm in the Aspira group (0.05 ± 0.03 than in the Tecnis group (0.03 ± 0.02 (p=0.001. Strehl ratio was higher in eyes with Tecnis (0.28 ± 0.17 with a minimal pupil size larger than 5 mm than that with Aspira (0.16 ± 0.14 (p=0.04. In pupils with a minimum diameter of 4 mm spherical aberration had a significant effect on Strehl ratio, but not in pupils with a diameter less than 4 mm. Conclusions. Optical quality was better in eyes with the aberration-correcting Tecnis IOL when pupils were large. In contrast, this could not be shown in eyes with pupils under 4 mm or larger. This trial is registered with Clinicaltrials.gov NCT03224728.

  16. Bone scans

    International Nuclear Information System (INIS)

    Hetherington, V.J.

    1989-01-01

    Oftentimes, in managing podiatric complaints, clinical and conventional radiographic techniques are insufficient in determining a patient's problem. This is especially true in the early stages of bone infection. Bone scanning or imaging can provide additional information in the diagnosis of the disorder. However, bone scans are not specific and must be correlated with clinical, radiographic, and laboratory evaluation. In other words, bone scanning does not provide the diagnosis but is an important bit of information aiding in the process of diagnosis. The more useful radionuclides in skeletal imaging are technetium phosphate complexes and gallium citrate. These compounds are administered intravenously and are detected at specific time intervals postinjection by a rectilinear scanner with minification is used and the entire skeleton can be imaged from head to toe. Minification allows visualization of the entire skeleton in a single image. A gamma camera can concentrate on an isolated area. However, it requires multiple views to complete the whole skeletal image. Recent advances have allowed computer augmentation of the data received from radionucleotide imaging. The purpose of this chapter is to present the current radionuclides clinically useful in podiatric patients

  17. Effects of residual aberrations explored on single-walled carbon nanotubes

    International Nuclear Information System (INIS)

    Biskupek, Johannes; Hartel, Peter; Haider, Maximilian; Kaiser, Ute

    2012-01-01

    The effects of geometric residual aberrations such as coma B 2 and two-fold astigmatism A 1 on the contrast in aberration corrected high resolution transmission electron microscopy (HRTEM) images are investigated on single-walled carbon nanotubes (SWNT). The individual aberrations are adjusted and set up manually using an imaging C S -corrector. We demonstrate how coma B 2 can be recognized by an experienced user directly in the image and how it blurs the contrast. Even with uncorrected (resolution limiting) spherical aberration C S the coma B 2 has to be considered and must be minimized. Limits for a tolerable coma are given. The experiments are confirmed by image simulations. -- Highlights: ► Individual effects of residual aberrations such as B 2 , A 1 , and C S are demonstrated. ► Experimental HRTEM and simulated images of carbon nanotubes are compared. ► A detection limit of 50 nm B 2 in a single HRTEM image is determined.

  18. Bone scan in mastocytosis: case report

    International Nuclear Information System (INIS)

    Sy, W.M.; Bonventre, M.V.; Camera, A.

    1976-01-01

    A 45-year-old man with well-documented systemic mastocytosis showed generalized symmetric increased activity on bone imaging. These scan findings are grossly indistinguishable from those of patients with renal osteodystrophy or secondary hyperparathyroidism. The images of the hands, however, failed to show the changes observed in secondary hyperparathyroidism. The mechanism for this intense activity is thought to be due to aberrant new-bone formation

  19. Recurrent branchial sinus tract with aberrant extension.

    Science.gov (United States)

    Barret, J P

    2004-01-01

    Second branchial cysts are the commonest lesions among congenital lateral neck anomalies. Good knowledge of anatomy and embryology are necessary for proper treatment. Surgical treatment involves resection of all branchial remnants, which extend laterally in the neck, medial to the sternocleidomastoid muscle with cranial extension to the pharynx and ipsilateral tonsillar fosa. However, infections and previous surgery can distort anatomy, making the approach to branchial anomalies more difficult. We present a case of a 17-year-old patient who presented with a second branchial tract anomaly with an aberrant extension to the midline and part of the contralateral neck. Previous surgical interventions and chronic infections may have been the primary cause for this aberrant tract. All head and neck surgeons should bear in mind that aberrant presentations may exist when reoperating on chronic branchial cysts fistulas.

  20. An aberrant precision account of autism.

    Directory of Open Access Journals (Sweden)

    Rebecca P Lawson

    2014-05-01

    Full Text Available Autism is a neurodevelopmental disorder characterised by problems with social-communication, restricted interests and repetitive behaviour. A recent and controversial article presented a compelling normative explanation for the perceptual symptoms of autism in terms of a failure of Bayesian inference (Pellicano and Burr, 2012. In response, we suggested that when Bayesian interference is grounded in its neural instantiation – namely, predictive coding – many features of autistic perception can be attributed to aberrant precision (or beliefs about precision within the context of hierarchical message passing in the brain (Friston et al., 2013. Here, we unpack the aberrant precision account of autism. Specifically, we consider how empirical findings – that speak directly or indirectly to neurobiological mechanisms – are consistent with the aberrant encoding of precision in autism; in particular, an imbalance of the precision ascribed to sensory evidence relative to prior beliefs.

  1. Chromosomal aberrations induced by alpha particles

    International Nuclear Information System (INIS)

    Guerrero C, C.; Brena V, M.

    2005-01-01

    The chromosomal aberrations produced by the ionizing radiation are commonly used when it is necessary to establish the exposure dose of an individual, it is a study that is used like complement of the traditional physical systems and its application is only in cases in that there is doubt about what indicates the conventional dosimetry. The biological dosimetry is based on the frequency of aberrations in the chromosomes of the lymphocytes of the individual in study and the dose is calculated taking like reference to the dose-response curves previously generated In vitro. A case of apparent over-exposure to alpha particles to which is practiced analysis of chromosomal aberrations to settle down if in fact there was exposure and as much as possible, to determine the presumed dose is presented. (Author)

  2. Electrostatic axisymmetric mirror with removable spherical aberration

    International Nuclear Information System (INIS)

    Birmuzaev, S.B.; Serikbaeva, G.S.; Hizirova, M.A.

    1999-01-01

    The electrostatic axisymmetric mirror, assembled from three coaxial cylinders with an equal diameter d and under the potential v1, v2 and v3, was computed. The proportions of geometrical and electric parameters of the mirror, with which the spherical 3-order aberration may be eliminated, were determined. The computation outcomes of the case, when the focal power of the mirror is enough large and the object plane in the focus is out of its field, are presented (Fig. 1 - potentials proportion that makes elimination of the spherical aberration possible; Fig. 2 - the focus coordinates when the spherical aberration is eliminated). The geometrical values are presented by d, and the electric ones are presented by v1. The figures on the curves present a length of the second (middle) electrode. The zero point is located in the middle of the gap between the first and second electrodes The investigated mirror may be used as a lens for the transmission electron microscope

  3. In-situ environmental (scanning) transmission electron microscopy of catalysts at the atomic level

    International Nuclear Information System (INIS)

    Gai, P L; Boyes, E D

    2014-01-01

    Observing reacting single atoms on the solid catalyst surfaces under controlled reaction conditions is a key goal in understanding and controlling heterogeneous catalytic reactions. In-situ real time aberration corrected environmental (scanning) transmission electron microscopy (E(S)TEM permit the direct imaging of dynamic surface and sub-surface structures of reacting catalysts. In this paper in-situ AC ETEM and AC ESTEM studies under controlled reaction environments of oxide catalysts and supported metal nanocatalysts important in chemical industry are presented. They provide the direct evidence of dynamic processes at the oxide catalyst surface at the atomic scale and single atom dynamics in catalytic reactions. The ESTEM studies of single atom dynamics in controlled reaction environments show that nanoparticles act as reservoirs of ad-atoms. The results have important implications in catalysis and nanoparticle studies

  4. Atomic-scale Ge diffusion in strained Si revealed by quantitative scanning transmission electron microscopy

    Science.gov (United States)

    Radtke, G.; Favre, L.; Couillard, M.; Amiard, G.; Berbezier, I.; Botton, G. A.

    2013-05-01

    Aberration-corrected scanning transmission electron microscopy is employed to investigate the local chemistry in the vicinity of a Si0.8Ge0.2/Si interface grown by molecular-beam epitaxy. Atomic-resolution high-angle annular dark field contrast reveals the presence of a nonuniform diffusion of Ge from the substrate into the strained Si thin film. On the basis of multislice calculations, a model is proposed to quantify the experimental contrast, showing that the Ge concentration in the thin film reaches about 4% at the interface and decreases monotonically on a typical length scale of 10 nm. Diffusion occurring during the growth process itself therefore appears as a major factor limiting the abruptness of interfaces in the Si-Ge system.

  5. Scanning laser ophthalmoscope design with adaptive optics

    OpenAIRE

    Laut, SP; Jones, SM; Olivier, SS; Werner, JS

    2005-01-01

    A design for a high-resolution scanning instrument is presented for in vivo imaging of the human eye at the cellular scale. This system combines adaptive optics technology with a scanning laser ophthalmoscope (SLO) to image structures with high lateral (∼2 μm) resolution. In this system, the ocular wavefront aberrations that reduce the resolution of conventional SLOs are detected by a Hartmann-Shack wavefront sensor, and compensated with two deformable mirrors in a closed-loop for dynamic cor...

  6. Quality factor of aberrated gaussian laser beams

    CSIR Research Space (South Africa)

    Mafusire, C

    2010-09-01

    Full Text Available 15 20 25 30 35 M 4 © CSIR 2010 www.csir.co.za Conclusion • Laser beam quality depends on - y-Astigmatism - y-Coma - x-Coma - y-Triangular astigmatism - x-Triangular astigmatism - Spherical aberration...

  7. Local chromatic correction scheme for LER of PEP-II

    International Nuclear Information System (INIS)

    Forest, E.; Robin, D.; Zholents, A.; Donald, M.; Helm, R.; Irwin, J.; Sullivan, M.K.

    1993-01-01

    The correction of the chromaticity of low-beta insertions in storage rings is usually made with sextupole lenses in the ring arcs. When decreasing the beta functions at the interaction point (IP), this technique becomes fairly ineffective, since it fails to properly correct the higher-order chromatic aberrations. Here we consider the approach for ampersand PEP-II B Factory low energy ring (LER) where the chromatic effects of the quadrupole lenses generating low beta functions at the IP are corrected locally with two families of sextupoles, one family for each plane. For the IP straight section the lattice is designed in such a way that the chromatic aberrations are made small and sextupole-like aberrations are eliminated. The results of dimensional tracking simulations are presented

  8. Non-random intrachromosomal distribution of radiation-induced chromatid aberrations in Vicia faba. [Aberration clustering

    Energy Technology Data Exchange (ETDEWEB)

    Schubert, I; Rieger, R [Akademie der Wissenschaften der DDR, Gatersleben. Zentralinst. fuer Genetik und Kulturpflanzenforschung

    1976-04-01

    A reconstructed karyotype of Vicia faba, with all chromosomes individually distinguishable, was treated with X-rays, fast neutrons, (/sup 3/H) uridine (/sup 3/HU). The distribution within metaphase chromosomes of induced chromatid aberrations was non-random for all agents used. Aberration clustering, in part agent specific, occurred in chromosome segments containing heterochromatin as defined by the presence of G bands. The pattern of aberration clustering found after treatment with /sup 3/HU did not allow the recognition of chromosome regions active in transcription during treatment. Furthermore, it was impossible to obtain unambiguous indications of the presence of AT- and GC-base clusters from the patterns of /sup 3/HT- and /sup 3/HC-induced chromatid aberrations, respectively. Possible reasons underlying these observations are discussed.

  9. Performance evaluation of spatial compounding in the presence of aberration and adaptive imaging

    Science.gov (United States)

    Dahl, Jeremy J.; Guenther, Drake; Trahey, Gregg E.

    2003-05-01

    Spatial compounding has been used for years to reduce speckle in ultrasonic images and to resolve anatomical features hidden behind the grainy appearance of speckle. Adaptive imaging restores image contrast and resolution by compensating for beamforming errors caused by tissue-induced phase errors. Spatial compounding represents a form of incoherent imaging, whereas adaptive imaging attempts to maintain a coherent, diffraction-limited aperture in the presence of aberration. Using a Siemens Antares scanner, we acquired single channel RF data on a commercially available 1-D probe. Individual channel RF data was acquired on a cyst phantom in the presence of a near field electronic phase screen. Simulated data was also acquired for both a 1-D and a custom built 8x96, 1.75-D probe (Tetrad Corp.). The data was compounded using a receive spatial compounding algorithm; a widely used algorithm because it takes advantage of parallel beamforming to avoid reductions in frame rate. Phase correction was also performed by using a least mean squares algorithm to estimate the arrival time errors. We present simulation and experimental data comparing the performance of spatial compounding to phase correction in contrast and resolution tasks. We evaluate spatial compounding and phase correction, and combinations of the two methods, under varying aperture sizes, aperture overlaps, and aberrator strength to examine the optimum configuration and conditions in which spatial compounding will provide a similar or better result than adaptive imaging. We find that, in general, phase correction is hindered at high aberration strengths and spatial frequencies, whereas spatial compounding is helped by these aberrators.

  10. Chromatic aberration compensation in numerical reconstruction of digital holograms by Fresnel-Bluestein propagation.

    Science.gov (United States)

    Hincapie, Diego; Velasquez, Daniel; Garcia-Sucerquia, Jorge

    2017-12-15

    In this Letter, we present a method for chromatic compensation in numerical reconstruction of digitally recorded holograms based on Fresnel-Bluestein propagation. The proposed technique is applied to correct the chromatic aberration that arises in the reconstruction of RGB holograms of both millimeter- and micrometer-sized objects. The results show the feasibility of this strategy to remove the wavelength dependence of the size of the numerically propagated wavefields.

  11. The prediction of spherical aberration with schematic eyes.

    Science.gov (United States)

    Liou, H L; Brennan, N A

    1996-07-01

    Many model eyes have been proposed; they differ in optical characteristics and therefore have different aberrations and image quality. In predicting the visual performance of the eye, we are most concerned with the central foveal vision. Spherical aberration is the only on-axis monochromatic aberration and can be used as a criterion to assess the degree of resemblance of eye models to the human eye. We reviewed and compiled experimental values of the spherical aberration of the eye, calculated the spherical aberration of several different categories of model eyes and compared the calculated results to the experimental data. Results show an over-estimation of spherical aberration by all models, the finite schematic eyes predicting values of spherical aberration closest to the experimental data. Current model eyes do not predict the average experimental values of the spherical aberration of the eye. A new model eye satisfying this assessment criterion is required for investigations of the visual performance of the eye.

  12. Theoretical investigation of aberrations upon ametropic human eyes

    Science.gov (United States)

    Tan, Bo; Chen, Ying-Ling; Lewis, J. W. L.; Baker, Kevin

    2003-11-01

    The human eye aberrations are important for visual acuity and ophthalmic diagnostics and surgical procedures. Reported monochromatic aberration data of the normal 20/20 human eyes are scarce. There exist even fewer reports of the relation between ametropic conditions and aberrations. We theoretically investigate the monochromatic and chromatic aberrations of human eyes for refractive errors of -10 to +10 diopters. Schematic human eye models are employed using optical design software for axial, index, and refractive types of ametropia.

  13. Differentiated Effects of Sensory Activities as Abolishing Operations via Non-Contingent Reinforcement on Academic and Aberrant Behavior

    Science.gov (United States)

    Mancil, G. Richmond; Haydon, Todd; Boman, Marty

    2016-01-01

    The purpose of the study was to evaluate the effectiveness of sensory activities used as antecedent interventions on the percentage correct on academic tasks and rate of aberrant behavior in three elementary aged children with Autism Spectrum Disorders (ASD). Study activities were conducted in an after school program for children with ASD where…

  14. Depth-of-Focus and its Association with the Spherical Aberration Sign. A Ray-Tracing Analysis

    Directory of Open Access Journals (Sweden)

    Ravi C. Bakaraju

    2010-01-01

    Conclusions: As regards presbyopic-correction strategies that use deliberately induced aberrations to increase the depth of focus, the current study suggests that both positive and negative SA have equal potential. However, practical considerations will probably limit the useful DoF achievable through the utilization of SCE in presbyopes. for reference to a contemporary record detailing refractive history.

  15. Ocular higher-order aberrations in a school children population

    Directory of Open Access Journals (Sweden)

    George Papamastorakis

    2015-04-01

    Conclusions: Differences in the low levels of ocular spherical aberration in young children possibly reflect differences in lenticular spherical aberration and relate to the gradient refractive index of the lens. The evaluation of spherical aberration at certain stages of eye growth may help to better understand the underlying mechanisms of myopia development.

  16. Publisher Correction

    DEFF Research Database (Denmark)

    Stokholm, Jakob; Blaser, Martin J.; Thorsen, Jonathan

    2018-01-01

    The originally published version of this Article contained an incorrect version of Figure 3 that was introduced following peer review and inadvertently not corrected during the production process. Both versions contain the same set of abundance data, but the incorrect version has the children...

  17. Publisher Correction

    DEFF Research Database (Denmark)

    Flachsbart, Friederike; Dose, Janina; Gentschew, Liljana

    2018-01-01

    The original version of this Article contained an error in the spelling of the author Robert Häsler, which was incorrectly given as Robert Häesler. This has now been corrected in both the PDF and HTML versions of the Article....

  18. Correction to

    DEFF Research Database (Denmark)

    Roehle, Robert; Wieske, Viktoria; Schuetz, Georg M

    2018-01-01

    The original version of this article, published on 19 March 2018, unfortunately contained a mistake. The following correction has therefore been made in the original: The names of the authors Philipp A. Kaufmann, Ronny Ralf Buechel and Bernhard A. Herzog were presented incorrectly....

  19. Wavefront correction performed by a deformable mirror of arbitrary actuator pattern within a multireflection waveguide.

    Science.gov (United States)

    Ma, Xingkun; Huang, Lei; Bian, Qi; Gong, Mali

    2014-09-10

    The wavefront correction ability of a deformable mirror with a multireflection waveguide was investigated and compared via simulations. By dividing a conventional actuator array into a multireflection waveguide that consisted of single-actuator units, an arbitrary actuator pattern could be achieved. A stochastic parallel perturbation algorithm was proposed to find the optimal actuator pattern for a particular aberration. Compared with conventional an actuator array, the multireflection waveguide showed significant advantages in correction of higher order aberrations.

  20. Effective absorption correction for energy dispersive X-ray mapping in a scanning transmission electron microscope: analysing the local indium distribution in rough samples of InGaN alloy layers.

    Science.gov (United States)

    Wang, X; Chauvat, M-P; Ruterana, P; Walther, T

    2017-12-01

    We have applied our previous method of self-consistent k*-factors for absorption correction in energy-dispersive X-ray spectroscopy to quantify the indium content in X-ray maps of thick compound InGaN layers. The method allows us to quantify the indium concentration without measuring the sample thickness, density or beam current, and works even if there is a drastic local thickness change due to sample roughness or preferential thinning. The method is shown to select, point-by-point in a two-dimensional spectrum image or map, the k*-factor from the local Ga K/L intensity ratio that is most appropriate for the corresponding sample geometry, demonstrating it is not the sample thickness measured along the electron beam direction but the optical path length the X-rays have to travel through the sample that is relevant for the absorption correction. © 2017 The Authors Journal of Microscopy © 2017 Royal Microscopical Society.

  1. Coronary artery with aberrant origin malignant right

    International Nuclear Information System (INIS)

    Ozcan, E.; Bozlar, U.; Demirkol, S.; Saglam, M.

    2012-01-01

    Full text: Introduction: Congenital anomalies of the coronary arteries is a major cause of sudden death, especially in young patients. Objectives and tasks: In this study we aim to present a young patient with chest pain who had malignant right coronary artery (RCA) with aberrant origin. Materials and methods: 24-year-old man who applied cardiology clinic for chest pain and palpitations especially after exercise, was referred to our clinic for coronary computed tomography (CT) angiography to evaluate coronary artery anomalies. Results: In CT angiography; we detected aberrant RCA with origin of tubularly part of ascendant aorta with a malignant course between aorta and pulmonary artery. Left main coronary artery, left anterior descending and circumflex artery had normal origin and course. Conclusion: Coronary artery with malignant course may cause sudden death especially after exercise. Coronary CT angiography has an important role in diagnosis of congenital coronary artery anomalies, with high resolution multiplanner reformatted images

  2. Assessing the construct validity of aberrant salience

    Directory of Open Access Journals (Sweden)

    Kristin Schmidt

    2009-12-01

    Full Text Available We sought to validate the psychometric properties of a recently developed paradigm that aims to measure salience attribution processes proposed to contribute to positive psychotic symptoms, the Salience Attribution Test (SAT. The “aberrant salience” measure from the SAT showed good face validity in previous results, with elevated scores both in high-schizotypy individuals, and in patients with schizophrenia suffering from delusions. Exploring the construct validity of salience attribution variables derived from the SAT is important, since other factors, including latent inhibition/learned irrelevance, attention, probabilistic reward learning, sensitivity to probability, general cognitive ability and working memory could influence these measures. Fifty healthy participants completed schizotypy scales, the SAT, a learned irrelevance task, and a number of other cognitive tasks tapping into potentially confounding processes. Behavioural measures of interest from each task were entered into a principal components analysis, which yielded a five-factor structure accounting for ~75% percent of the variance in behaviour. Implicit aberrant salience was found to load onto its own factor, which was associated with elevated “Introvertive Anhedonia” schizotypy, replicating our previous finding. Learned irrelevance loaded onto a separate factor, which also included implicit adaptive salience, but was not associated with schizotypy. Explicit adaptive and aberrant salience, along with a measure of probabilistic learning, loaded onto a further factor, though this also did not correlate with schizotypy. These results suggest that the measures of learned irrelevance and implicit adaptive salience might be based on similar underlying processes, which are dissociable both from implicit aberrant salience and explicit measures of salience.

  3. Aberrant PO2 values in proficiency testing.

    Science.gov (United States)

    Fonzi, C E; Clausen, J L; Mahoney, J

    1993-03-01

    We prospectively determined the frequency of aberrant vials of fluorocarbon/buffer used for proficiency testing of measurements of pH, PCO2, and PO2, using 20 duplicate vials from 12 lots of fluorocarbon/buffer and two arterial blood gas analyzers in eight reference laboratories. We defined aberrant vials as vials for which both duplicate measurements differed from the mean value of repeated measurements for the specific instrument (for each lot of testing materials) by > 0.04 for pH, > 10% of the mean or 3.0 mm Hg, whichever was greater, for PCO2; or > 10% of the mean or 6 mm Hg, whichever was greater, for PO2. Four of 1620 vials (0.25%) were aberrant, all based on PO2 measurements (range of mean values: pH, 7.181-7.631; PCO2, 12.7-65.9; PO2, 32.5-150.1) were 0.0055 for pH, 0.67 mm Hg for PCO2, and 1.65 mm Hg for PO2. Deliberate contamination of the fluorocarbon emulsion with room air, as might occur during sampling from the vial, indicated that only minor increases in PO2 (e.g., 1.0 mm Hg at PO2 of 56 mm Hg) occur when samples are aspirated. Larger increases in PO2 (mean 7.1 mm Hg at a PO2 of 66 mm Hg) occurred when the syringe samples were contaminated with room air. We conclude that isolated aberrant measurements of PO2 in blood gas proficiency testing attributable to vial contents can occur, but the frequency is very low.

  4. Three-Dimensional scanning transmission electron microscopy of biological specimens

    KAUST Repository

    De Jonge, Niels

    2010-01-18

    A three-dimensional (3D) reconstruction of the cytoskeleton and a clathrin-coated pit in mammalian cells has been achieved from a focal-series of images recorded in an aberration-corrected scanning transmission electron microscope (STEM). The specimen was a metallic replica of the biological structure comprising Pt nanoparticles 2-3 nm in diameter, with a high stability under electron beam radiation. The 3D dataset was processed by an automated deconvolution procedure. The lateral resolution was 1.1 nm, set by pixel size. Particles differing by only 10 nm in vertical position were identified as separate objects with greater than 20% dip in contrast between them. We refer to this value as the axial resolution of the deconvolution or reconstruction, the ability to recognize two objects, which were unresolved in the original dataset. The resolution of the reconstruction is comparable to that achieved by tilt-series transmission electron microscopy. However, the focal-series method does not require mechanical tilting and is therefore much faster. 3D STEM images were also recorded of the Golgi ribbon in conventional thin sections containing 3T3 cells with a comparable axial resolution in the deconvolved dataset. © 2010 Microscopy Society of America.

  5. Novel low-dose imaging technique for characterizing atomic structures through scanning transmission electron microscope

    Science.gov (United States)

    Su, Chia-Ping; Syu, Wei-Jhe; Hsiao, Chien-Nan; Lai, Ping-Shan; Chen, Chien-Chun

    2017-08-01

    To investigate dislocations or heterostructures across interfaces is now of great interest to condensed matter and materials scientists. With the advances in aberration-corrected electron optics, the scanning transmission electron microscope has demonstrated its excellent capability of characterizing atomic structures within nanomaterials, and well-resolved atomic-resolution images can be obtained through long-exposure data acquisition. However, the sample drifting, carbon contamination, and radiation damage hinder further analysis, such as deriving three-dimensional (3D) structures from a series of images. In this study, a method for obtaining atomic-resolution images with significantly reduced exposure time was developed, using which an original high-resolution image with approximately one tenth the electron dose can be obtained by combining a fast-scan high-magnification image and a slow-scan low-magnification image. The feasibility of obtaining 3D atomic structures using the proposed approach was demonstrated through multislice simulation. Finally, the feasibility and accuracy of image restoration were experimentally verified. This general method cannot only apply to electron microscopy but also benefit to image radiation-sensitive materials using various light sources.

  6. Head CT scan

    Science.gov (United States)

    ... scan - orbits; CT scan - sinuses; Computed tomography - cranial; CAT scan - brain ... head size in children Changes in thinking or behavior Fainting Headache, when you have certain other signs ...

  7. Study of radiation-induced chromosomal aberrations

    International Nuclear Information System (INIS)

    Wolfring, E.

    2004-06-01

    A method for determining chromosomal aberrations was established for the purpose of examining the relative biological effectiveness (RBE) of photon radiation with respect to mammary epithelium cells. Cells were exposed to 25 kV X-radiation and to 200 kV X-radiation for comparison and the resulting concentrations of chromosomal aberrations were compared. The RBE M value for radiation-induced fragmentation was found to be 4.2 ± 2.4, while the RBE M value for radiation-induced generation of dicentric chromosomes was found to be 0.5 ± 0.5. In addition to the evaluation of chromosomal aberrations the number of cell cycles undergone by the cells was monitored by means of BrDU staining. As expected, the proportion of cells which underwent more than one cell cycle following exposure to 5 Gy was very low in both cases, amounting to 1.9% (25 kV) and 3.2 (200 kV). Non-radiated cells yielded control values of 26.0% and 12.6%, suggesting variations in external conditions from day to day

  8. Chromosome aberration assays in barley (Hordeum vulgare)

    Energy Technology Data Exchange (ETDEWEB)

    Constantin, M J [Univ. of Tennessee, Knoxville; Nilan, R A

    1982-01-01

    Barley is an exceellent organism for studies of induced chromosome aberrations because of its few (2n = 2x = 14) relatively large chromosomes. Root-tip and shoot-tip cells have been used extensively for the study of ionizing radiation-induced chromosome aberrations. The general procedures are well known, the technology is simple and easy to learn, and the assays are relatively quick and inexpensive. Both root tips and shoot tips can be used for the study of chemical mutagens as well as ionizing radiations. Pollen mother cells are well suited for studying the effects of mutagens on meiotic chromosomes. The literature review for the Gene-Tox Program reported on 61 chemicals tested for their effects on barley chromosomes. Of these, 90% were reported to be either positive or positive dose-related, while 7% were negative and 3% were questionable. Barley assays based on chromosomal aberrations are useful to detect the clastogenic potency of chemicals under laboratory conditions. Indications are that the data from barley can be used to corroborate data obtained from other organisms. Among the classes of chemicals assayed were: alcohols and phenols; alkaloids; epoxides; alkyl sulfates; amides and sulfonamides; aromatic amines; aryl halides; aziridines; alkenes; carbamates; hydroazides; nitroaromatics; nitrosamides; nitrosources; phenothiazines; and polycyclic aromatic hydrocarbons.

  9. Aberrant phenotypes in peripheral T cell lymphomas.

    Science.gov (United States)

    Hastrup, N; Ralfkiaer, E; Pallesen, G

    1989-01-01

    Seventy six peripheral T cell lymphomas were examined immunohistologically to test their reactivity with a panel of monoclonal antibodies against 11 T cell associated antigens (CD1-8, CD27, UCHL1, and the T cell antigen receptor). Sixty two (82%) lymphomas showed aberrant phenotypes, and four main categories were distinguished as follows: (i) lack of one or several pan-T cell antigens (49, 64% of the cases); (ii) loss of both the CD4 and CD8 antigens (11, 15% of the cases); (iii) coexpression of the CD4 and CD8 antigens (13, 17% of the cases); and (iv) expression of the CD1 antigen (eight, 11% of the cases). No correlation was seen between the occurrence of aberrant phenotypes and the histological subtype. It is concluded that the demonstration of an aberrant phenotype is a valuable supplement to histological assessment in the diagnosis of peripheral T cell lymphomas. It is recommended that the panel of monoclonal antibodies against T cell differentiation antigens should be fairly large, as apparently any antigen may be lost in the process of malignant transformation. Images Figure PMID:2469701

  10. Aberration changes of the corneal anterior surface following discontinued use of rigid gas permeable contact lenses.

    Science.gov (United States)

    Yu, Qing; Wu, Jiang-Xiu; Zhang, He-Ning; Ye, Sheng; Dong, Shi-Qi; Zhang, Chen-Hao

    2013-01-01

    To record aberrations with a corneal topographic device on the anterior surface of the cornea at different time-points prior to wearing and following discontinued use of rigid gas permeable (RGP) contact lenses. The effect of wearing RGP on the anterior surface of the cornea was discussed to provide guidance for clinical refractive error correction. The study objects were 24 eyes from 24 patients. All patients underwent identical examination procedures prior to lens use, as well as afterwards, including slit-lamp examination, non-contact tonometer measurement, computer optometry and corneal curvature measurement, subjective refraction test, and corneal topography analysis. The patients wore contact lenses everyday for 1 month and then discontinued. Corneal topographies were recorded at certain time points of 30 minutes, 1 day, 3, 7 and 14 days following use. Total corneal aberration at each time point following discontinued use of RGP contact lenses was less than the time point prior to use. Detailed results were as follows: root mean square (RMS) (pre)=(1.438±0.328)µm, RMS (30 minutes)=(1.076±0.355)µm, RMS (1 day)=(1.362±0.402)µm, RMS (3 days)=(1.373±0.398)µm, RMS (7 days)=(1.387±0.415)µm, and RMS (14 days)=(1.430±0.423)µm. Results showed that at 30 minutes after discontinued use of RGP contact lenses, almost all 2(nd)- and 3(rd)-order aberrations change. Quadrafoil Z10 and spherical Z12 of the 4(th)-order were also changed. Alterations to Z5, Z6, and Z12 at 1 day after discontinued use were significant differences compared with the time period prior to RGP use: Z5 and Z6 decreased, and Z12 increased slightly. Z5 and Z6 remained decreased at 3 days after discontinued use, but Z9 and Z10 continued to increase and Z12 returned to levels prior to RGP use. At 14 days after discontinued use, all aberrations were not significantly different from the values prior to use. The use RGP contact lenses greatly reduced total aberration of the anterior surface of

  11. Chromosome painting in biological dosimetry: Semi-automatic system to score stable chromosome aberrations

    International Nuclear Information System (INIS)

    Garcia-Sagredo, J.M.; Vallcorba, I.; Sanchez-Hombre, M.C.; Ferro, M.T.; San Roman Cos-Gayon, C.; Santos, A.; Malpica, N.; Ortiz, C.

    1997-01-01

    From the beginning of the description of the procedure of chromosome painting by fluorescence in situ hybridization (FISH), it was thought its possible application to score induced chromosomal aberrations in radiation exposition. With chromosome painting it is possible to detect changes between chromosomes that has been validated in radiation exposition. Translocation scoring by FISH, contrarily to the unstable dicentrics, mainly detect stable chromosome aberrations that do not disappear, it allows the capability of quantify delayed acute expositions or chronic cumulative expositions. The large number of cells that have to be analyzed for high accuracy, specially when dealing with low radiation doses, makes it almost imperative to use an automatic analysis system. After validate translocation scoring by FISH in our, we have evaluated the ability and sensitivity to detect chromosomal aberrations by chromosome using different paint probes used, showing that any combination of paint probes can be used to score induced chromosomal aberrations. Our group has developed a FISH analysis that is currently being adapted for translocation scoring analysis. It includes systematic error correction and internal control probes. The performance tests carried out show that 9,000 cells can be analyzed in 10 hr. using a Sparc 4/370. Although with a faster computer, a higher throughput is expected, for large population screening or very low radiation doses, this performance still has to be improved. (author)

  12. Corrective Jaw Surgery

    Medline Plus

    Full Text Available ... out more. Corrective Jaw Surgery Corrective Jaw Surgery Orthognathic surgery is performed to correct the misalignment of jaws ... out more. Corrective Jaw Surgery Corrective Jaw Surgery Orthognathic surgery is performed to correct the misalignment of jaws ...

  13. Nodal aberration theory for wild-filed asymmetric optical systems

    Science.gov (United States)

    Chen, Yang; Cheng, Xuemin; Hao, Qun

    2016-10-01

    Nodal Aberration Theory (NAT) was used to calculate the zero field position in Full Field Display (FFD) for the given aberration term. Aiming at wide-filed non-rotational symmetric decentered optical systems, we have presented the nodal geography behavior of the family of third-order and fifth-order aberrations. Meanwhile, we have calculated the wavefront aberration expressions when one optical element in the system is tilted, which was not at the entrance pupil. By using a three-piece-cellphone lens example in optical design software CodeV, the nodal geography is testified under several situations; and the wavefront aberrations are calculated when the optical element is tilted. The properties of the nodal aberrations are analyzed by using Fringe Zernike coefficients, which are directly related with the wavefront aberration terms and usually obtained by real ray trace and wavefront surface fitting.

  14. Direct Visualization of Local Electromagnetic Field Structures by Scanning Transmission Electron Microscopy.

    Science.gov (United States)

    Shibata, Naoya; Findlay, Scott D; Matsumoto, Takao; Kohno, Yuji; Seki, Takehito; Sánchez-Santolino, Gabriel; Ikuhara, Yuichi

    2017-07-18

    The functional properties of materials and devices are critically determined by the electromagnetic field structures formed inside them, especially at nanointerface and surface regions, because such structures are strongly associated with the dynamics of electrons, holes and ions. To understand the fundamental origin of many exotic properties in modern materials and devices, it is essential to directly characterize local electromagnetic field structures at such defect regions, even down to atomic dimensions. In recent years, rapid progress in the development of high-speed area detectors for aberration-corrected scanning transmission electron microscopy (STEM) with sub-angstrom spatial resolution has opened new possibilities to directly image such electromagnetic field structures at very high-resolution. In this Account, we give an overview of our recent development of differential phase contrast (DPC) microscopy for aberration-corrected STEM and its application to many materials problems. In recent years, we have developed segmented-type STEM detectors which divide the detector plane into 16 segments and enable simultaneous imaging of 16 STEM images which are sensitive to the positions and angles of transmitted/scattered electrons on the detector plane. These detectors also have atomic-resolution imaging capability. Using these segmented-type STEM detectors, we show DPC STEM imaging to be a very powerful tool for directly imaging local electromagnetic field structures in materials and devices in real space. For example, DPC STEM can clearly visualize the local electric field variation due to the abrupt potential change across a p-n junction in a GaAs semiconductor, which cannot be observed by normal in-focus bright-field or annular type dark-field STEM imaging modes. DPC STEM is also very effective for imaging magnetic field structures in magnetic materials, such as magnetic domains and skyrmions. Moreover, real-time imaging of electromagnetic field structures can

  15. Electroweak corrections

    International Nuclear Information System (INIS)

    Beenakker, W.J.P.

    1989-01-01

    The prospect of high accuracy measurements investigating the weak interactions, which are expected to take place at the electron-positron storage ring LEP at CERN and the linear collider SCL at SLAC, offers the possibility to study also the weak quantum effects. In order to distinguish if the measured weak quantum effects lie within the margins set by the standard model and those bearing traces of new physics one had to go beyond the lowest order and also include electroweak radiative corrections (EWRC) in theoretical calculations. These higher-order corrections also can offer the possibility of getting information about two particles present in the Glashow-Salam-Weinberg model (GSW), but not discovered up till now, the top quark and the Higgs boson. In ch. 2 the GSW standard model of electroweak interactions is described. In ch. 3 some special techniques are described for determination of integrals which are responsible for numerical instabilities caused by large canceling terms encountered in the calculation of EWRC effects, and methods necessary to get hold of the extensive algebra typical for EWRC. In ch. 4 various aspects related to EWRC effects are discussed, in particular the dependence of the unknown model parameters which are the masses of the top quark and the Higgs boson. The processes which are discussed are production of heavy fermions from electron-positron annihilation and those of the fermionic decay of the Z gauge boson. (H.W.). 106 refs.; 30 figs.; 6 tabs.; schemes

  16. Genomic copy number analysis of a spectrum of blue nevi identifies recurrent aberrations of entire chromosomal arms in melanoma ex blue nevus.

    Science.gov (United States)

    Chan, May P; Andea, Aleodor A; Harms, Paul W; Durham, Alison B; Patel, Rajiv M; Wang, Min; Robichaud, Patrick; Fisher, Gary J; Johnson, Timothy M; Fullen, Douglas R

    2016-03-01

    Blue nevi may display significant atypia or undergo malignant transformation. Morphologic diagnosis of this spectrum of lesions is notoriously difficult, and molecular tools are increasingly used to improve diagnostic accuracy. We studied copy number aberrations in a cohort of cellular blue nevi, atypical cellular blue nevi, and melanomas ex blue nevi using Affymetrix's OncoScan platform. Cases with sufficient DNA were analyzed for GNAQ, GNA11, and HRAS mutations. Copy number aberrations were detected in 0 of 5 (0%) cellular blue nevi, 3 of 12 (25%) atypical cellular blue nevi, and 6 of 9 (67%) melanomas ex blue nevi. None of the atypical cellular blue nevi displayed more than one aberration, whereas complex aberrations involving four or more regions were seen exclusively in melanomas ex blue nevi. Gains and losses of entire chromosomal arms were identified in four of five melanomas ex blue nevi with copy number aberrations. In particular, gains of 1q, 4p, 6p, and 8q, and losses of 1p and 4q were each found in at least two melanomas. Whole chromosome aberrations were also common, and represented the sole finding in one atypical cellular blue nevus. When seen in melanomas, however, whole chromosome aberrations were invariably accompanied by partial aberrations of other chromosomes. Three melanomas ex blue nevi harbored aberrations, which were absent or negligible in their precursor components, suggesting progression in tumor biology. Gene mutations involving GNAQ and GNA11 were each detected in two of eight melanomas ex blue nevi. In conclusion, copy number aberrations are more common and often complex in melanomas ex blue nevi compared with cellular and atypical cellular blue nevi. Identification of recurrent gains and losses of entire chromosomal arms in melanomas ex blue nevi suggests that development of new probes targeting these regions may improve detection and risk stratification of these lesions.

  17. Assessment of refractive astigmatism and simulated therapeutic refractive surgery strategies in coma-like-aberrations-dominant corneal optics.

    Science.gov (United States)

    Zhou, Wen; Stojanovic, Aleksandar; Utheim, Tor Paaske

    2016-01-01

    The aim of the study is to raise the awareness of the influence of coma-like higher-order aberrations (HOAs) on power and orientation of refractive astigmatism (RA) and to explore how to account for that influence in the planning of topography-guided refractive surgery in eyes with coma-like-aberrations-dominant corneal optics. Eleven eyes with coma-like-aberrations-dominant corneal optics and with low lenticular astigmatism (LA) were selected for astigmatism analysis and for treatment simulations with topography-guided custom ablation. Vector analysis was used to evaluate the contribution of coma-like corneal HOAs to RA. Two different strategies were used for simulated treatments aiming to regularize irregular corneal optics: With both strategies correction of anterior corneal surface irregularities (corneal HOAs) were intended. Correction of total corneal astigmatism (TCA) and RA was intended as well with strategies 1 and 2, respectively. Axis of discrepant astigmatism (RA minus TCA minus LA) correlated strongly with axis of coma. Vertical coma influenced RA by canceling the effect of the with-the-rule astigmatism and increasing the effect of the against-the-rule astigmatism. After simulated correction of anterior corneal HOAs along with TCA and RA (strategies 1 and 2), only a small amount of anterior corneal astigmatism (ACA) and no TCA remained after strategy 1, while considerable amount of ACA and TCA remained after strategy 2. Coma-like corneal aberrations seem to contribute a considerable astigmatic component to RA in eyes with coma-like-aberrations dominant corneal optics. If topography-guided ablation is programmed to correct the corneal HOAs and RA, the astigmatic component caused by the coma-like corneal HOAs will be treated twice and will result in induced astigmatism. Disregarding RA and treating TCA along with the corneal HOAs is recommended instead.

  18. Survival and transmission of symmetrical chromosomal aberrations

    International Nuclear Information System (INIS)

    Savage, J.R.K.

    1979-01-01

    The interaction between the lesions to produce chromosomal structural changes may be either asymmetrical (A) or symmetrical (S). In A, one or more acentric fragments are always produced, and there may also be the mechanical separation problems resulting from bridges at anaphase, while S-changes never produce fragment, and pose no mechanical problem in cell division. If A and S events occur with equal frequency, it might be an indication that they are truly the alternative modes of lesion interaction. Unstimulated lymphocytes were irradiated with 2.68 Gy 250 kV X-ray, and metaphases were sampled at 50 h after the stimulation. Preparations were complete diploid cells, and any obvious second division cells were rejected. So far as dermal repair and fibroblast functions are concerned, aberration burden seems to have little consequence from the view-point of the long-term survival in vivo. Large numbers of aberrations (mainly S translocation and terminal deletion) were found in the samples taken up to 60 years after therapy. Skin biopsies were removed 1 day and 6 months after irradiation and cultured. In irradiated cells, reciprocal translocations dominated, followed by terminal deletions, then inversions, while no chromosome-type aberration was seen in the control cells. a) The relative occurrence of A : S changes, b) long-term survival in vivo, c) the possibility of in vivo repair, and d) some unusual features of translocation found in Syrian hamsters are reviewed. The relevance or importance of major S events is clearly dependent upon the cells, the tissues or the organisms in which they occur. (Yamashita, S.)

  19. Effective wavefront aberration measurement of spectacle lenses in as-worn status

    Science.gov (United States)

    Jia, Zhigang; Xu, Kai; Fang, Fengzhou

    2018-04-01

    An effective wavefront aberration analysis method for measuring spectacle lenses in as-worn status was proposed and verified using an experimental apparatus based on an eye rotation model. Two strategies were employed to improve the accuracy of measurement of the effective wavefront aberrations on the corneal sphere. The influences of three as-worn parameters, the vertex distance, pantoscopic angle, and face form angle, together with the eye rotation and corresponding incident beams, were objectively and quantitatively obtained. The experimental measurements of spherical single vision and freeform progressive addition lenses demonstrate the accuracy and validity of the proposed method and experimental apparatus, which provide a potential means of achieving supernormal vision correction with customization and personalization in optimizing the as-worn status-based design of spectacle lenses and evaluating their manufacturing and imaging qualities.

  20. Chromosome aberration model combining radiation tracks, chromatin structure, DSB repair and chromatin mobility

    International Nuclear Information System (INIS)

    Friedland, W.; Kundrat, P.

    2015-01-01

    The module that simulates the kinetics and yields of radiation-induced chromosome aberrations within the biophysical code PARTRAC is described. Radiation track structures simulated by Monte Carlo methods are overlapped with multi-scale models of DNA and chromatin to assess the resulting DNA damage. Spatial mobility of individual DNA ends from double-strand breaks is modelled simultaneously with their processing by the non-homologous end-joining enzymes. To score diverse types of chromosome aberrations, the joined ends are classified regarding their original chromosomal location, orientation and the involvement of centromeres. A comparison with experimental data on dicentrics induced by gamma and alpha particles shows that their relative dose dependence is predicted correctly, although the absolute yields are overestimated. The critical model assumptions on chromatin mobility and on the initial damage recognition and chromatin remodelling steps and their future refinements to solve this issue are discussed. (authors)

  1. A preliminary investigation into the effects of ocular lubricants on higher order aberrations in normal and dry eye subjects.

    Science.gov (United States)

    McGinnigle, Samantha; Eperjesi, Frank; Naroo, Shehzad A

    2014-04-01

    To study the effects of ocular lubricants on higher order aberrations in normal and self-diagnosed dry eyes. Unpreserved hypromellose drops, Tears Again™ liposome spray and a combination of both were administered to the right eye of 24 normal and 24 dry eye subjects following classification according to a 5 point questionnaire. Total ocular higher order aberrations, coma, spherical aberration and Strehl ratios for higher order aberrations were measured using the Nidek OPD-Scan III (Nidek Technologies, Gamagori, Japan) at baseline, immediately after application and after 60 min. The aberration data were analyzed over a 5mm natural pupil using Zernike polynomials. Each intervention was assessed on a separate day and comfort levels were recorded before and after application. Corneal staining was assessed and product preference recorded after the final measurement for each intervention. Hypromellose drops caused an increase in total higher order aberrations (p=dry eyes) and a reduction in Strehl ratio (normal eyes: p=dry eyes p=0.01) immediately after instillation. There were no significant differences between normal and self-diagnosed dry eyes for response to intervention and no improvement in visual quality or reduction in higher order aberrations after 60 min. Differences in comfort levels failed to reach statistical significance. Combining treatments does not offer any benefit over individual treatments in self-diagnosed dry eyes and no individual intervention reached statistical significance. Symptomatic subjects with dry eye and no corneal staining reported an improvement in comfort after using lubricants. Copyright © 2013 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

  2. Aberrant Myokine Signaling in Congenital Myotonic Dystrophy

    Directory of Open Access Journals (Sweden)

    Masayuki Nakamori

    2017-10-01

    Full Text Available Summary: Myotonic dystrophy types 1 (DM1 and 2 (DM2 are dominantly inherited neuromuscular disorders caused by a toxic gain of function of expanded CUG and CCUG repeats, respectively. Although both disorders are clinically similar, congenital myotonic dystrophy (CDM, a severe DM form, is found only in DM1. CDM is also characterized by muscle fiber immaturity not observed in adult DM, suggesting specific pathological mechanisms. Here, we revealed upregulation of the interleukin-6 (IL-6 myokine signaling pathway in CDM muscles. We also found a correlation between muscle immaturity and not only IL-6 expression but also expanded CTG repeat length and CpG methylation status upstream of the repeats. Aberrant CpG methylation was associated with transcriptional dysregulation at the repeat locus, increasing the toxic RNA burden that upregulates IL-6. Because the IL-6 pathway is involved in myocyte maturation and muscle atrophy, our results indicate that enhanced RNA toxicity contributes to severe CDM phenotypes through aberrant IL-6 signaling. : Congenital myotonic dystrophy (CDM manifests characteristic genetic (very large CTG repeat expansions, epigenetic (CpG hypermethylation upstream of the repeat, and phenotypic (muscle immaturity features not seen in adult DM. Nakamori et al. find phenotype-genotype and epigenotype correlation in CDM muscle and reveal involvement of the IL-6 myokine signaling pathway in the disease process. Keywords: CTCF, ER stress, IL-6, muscular dystrophy, NF-κB, trinucleotide, cytokine, splicing

  3. Higher order aberrations of the eye: Part one

    Directory of Open Access Journals (Sweden)

    Marsha Oberholzer

    2016-06-01

    Full Text Available This article is the first in a series of two articles that provide a comprehensive literature review of higher order aberrations (HOAs of the eye. The present article mainly explains the general principles of such HOAs as well as HOAs of importance, and the measuring apparatus used to measure HOAs of the eye. The second article in the series discusses factors contributing to variable results in measurements of HOAs of the eye. Keywords: Higher order aberrations; wavefront aberrations; aberrometer

  4. Chromosomal aberrations in children exposed to diagnostic x-rays

    International Nuclear Information System (INIS)

    Nordenson, I.; Beckman, G.; Beckman, L.; Lemperg, R.

    1980-01-01

    Among children who have received high x-ray doses congenital dislocation of the hip joint is the predominating diagnosis. In a series of 9 children who had received high x-ray doses (8 with luxation of the hip joint and one with achondroplasia) a significant increase of chromosomal aberrations was found. The increase concerned mainly chromosome type aberrations. The shorter the time since the last x-ray investigation the higher was the frequency of chromosome type aberrations. (author)

  5. Higher order monochromatic aberrations of the human infant eye

    OpenAIRE

    Wang, Jingyun; Candy, T. Rowan

    2005-01-01

    The monochromatic optical aberrations of the eye degrade retinal image quality. Any significant aberrations during postnatal development could contribute to infants’ immature visual performance and provide signals for the control of eye growth. Aberrations of human infant eyes from 5 to 7 weeks old were compared with those of adult subjects using a model of an adultlike infant eye that accounted for differences in both eye and pupil size. Data were collected using the COAS Shack-Hartmann wave...

  6. Brain PET scan

    Science.gov (United States)

    ... results on a PET scan. Blood sugar or insulin levels may affect the test results in people with diabetes . PET scans may be done along with a CT scan. This combination scan is called a PET/CT. Alternative Names Brain positron emission tomography; PET scan - brain References Chernecky ...

  7. Radiation-induced chromosome aberrations in the rat peripheral blood

    International Nuclear Information System (INIS)

    Ziemba-Zoltowska, B.; Bocian, E.; Radwan, I.; Rosiek, O.; Sablinski, J.

    1978-01-01

    Chromosome aberrations in rat lymphocytes of peripheral blood after X (in vitro and in vivo) and 3 H tritiated water (in vivo) irradiations were studied. The yield of chromosome aberrations after in vivo and in vitro exposure to X-rays was similar. The frequency of chromosome aberrations three weeks after exposure to X-rays and soon after irradiation was practically on the same level. The yield of chromosome aberrations determined three weeks after injection with tritiated water or X-rays exposure was similar. (author)

  8. Aberration design of zoom lens systems using thick lens modules.

    Science.gov (United States)

    Zhang, Jinkai; Chen, Xiaobo; Xi, Juntong; Wu, Zhuoqi

    2014-12-20

    A systematic approach for the aberration design of a zoom lens system using a thick lens module is presented. Each component is treated as a thick lens module at the beginning of the design. A thick lens module refers to a thick lens component with a real lens structure, like lens materials, lens curvatures, lens thicknesses, and lens interval distances. All nine third-order aberrations of a thick lens component are considered during the design. The relationship of component aberrations in different zoom positions can be approximated from the aberration shift. After minimizing the aberrations of the zoom lens system, the nine third-order aberrations of every lens component can be determined. Then the thick lens structure of every lens component can be determined after optimization according to their first-order properties and third-order aberration targets. After a third optimization for minimum practical third-order aberrations of a zoom lens system, the aberration design using the thick lens module is complete, which provides a practical zoom lens system with thick lens structures. A double-sided telecentric zoom lens system is designed using the thick lens module in this paper, which shows that this method is practical for zoom lens design.

  9. Chromosome aberration analysis for biological dosimetry: a review

    International Nuclear Information System (INIS)

    Paul, S.F.D.; Venkatachalam, P.; Jeevanram, R.K.

    1996-01-01

    Among various biological dosimetry techniques, dicentric chromosome aberration method appears to be the method of choice in analysing accidental radiation exposure in most of the laboratories. The major advantage of this method is its sensitivity as the number of dicentric chromosomes present in control population is too small and more importantly radiation induces mainly dicentric chromosome aberration among unstable aberration. This report brings out the historical development of various cytogenetic methods, the basic structure of DNA, chromosomes and different forms of chromosome aberrations. It also highlights the construction of dose-response curve for dicentric chromosome and its use in the estimation of radiation dose. (author)

  10. Imaging characteristics of Zernike and annular polynomial aberrations.

    Science.gov (United States)

    Mahajan, Virendra N; Díaz, José Antonio

    2013-04-01

    The general equations for the point-spread function (PSF) and optical transfer function (OTF) are given for any pupil shape, and they are applied to optical imaging systems with circular and annular pupils. The symmetry properties of the PSF, the real and imaginary parts of the OTF, and the modulation transfer function (MTF) of a system with a circular pupil aberrated by a Zernike circle polynomial aberration are derived. The interferograms and PSFs are illustrated for some typical polynomial aberrations with a sigma value of one wave, and 3D PSFs and MTFs are shown for 0.1 wave. The Strehl ratio is also calculated for polynomial aberrations with a sigma value of 0.1 wave, and shown to be well estimated from the sigma value. The numerical results are compared with the corresponding results in the literature. Because of the same angular dependence of the corresponding annular and circle polynomial aberrations, the symmetry properties of systems with annular pupils aberrated by an annular polynomial aberration are the same as those for a circular pupil aberrated by a corresponding circle polynomial aberration. They are also illustrated with numerical examples.

  11. Chromosome aberrations: plants to human and Feulgen to FISH

    International Nuclear Information System (INIS)

    Natarajan, A.T.

    2005-01-01

    Chromosome aberrations and their impact on human health have been recognized for a long time. In the 1950s, in India, studies on induced chromosome aberrations in plants were initiated by Swaminathan and his students. I trace here the impact of these initial studies on further developments in this field. The studies which were started in plants have been extended to mammals (including human) and the simple squash and solid staining have been improved by molecular cytogenetic techniques, thus enabling accurate identification and quantification of different types of chromosome aberrations. These studies have also thrown light on the mechanisms of chromosome aberration formation, especially following exposure to ionizing radiation. (author)

  12. Mouse manipulation through single-switch scanning.

    Science.gov (United States)

    Blackstien-Adler, Susie; Shein, Fraser; Quintal, Janet; Birch, Shae; Weiss, Patrice L Tamar

    2004-01-01

    Given the current extensive reliance on the graphical user interface, independent access to computer software requires that users be able to manipulate a pointing device of some type (e.g., mouse, trackball) or be able to emulate a mouse by some other means (e.g., scanning). The purpose of the present study was to identify one or more optimal single-switch scanning mouse emulation strategies. Four alternative scanning strategies (continuous Cartesian, discrete Cartesian, rotational, and hybrid quadrant/continuous Cartesian) were selected for testing based on current market availability as well as on theoretical considerations of their potential speed and accuracy. Each strategy was evaluated using a repeated measures study design by means of a test program that permitted mouse emulation via any one of four scanning strategies in a motivating environment; response speed and accuracy could be automatically recorded and considered in view of the motor, cognitive, and perceptual demands of each scanning strategy. Ten individuals whose disabilities required them to operate a computer via single-switch scanning participated in the study. Results indicated that Cartesian scanning was the preferred and most effective scanning strategy. There were no significant differences between results from the Continuous Cartesian and Discrete Cartesian scanning strategies. Rotational scanning was quite slow with respect to the other strategies, although it was equally accurate. Hybrid Quadrant scanning improved access time but at the cost of fewer correct selections. These results demonstrated the importance of testing and comparing alternate single-switch scanning strategies.

  13. Chromosomal aberrations and micronuclei frequencies in Bulgarian control population

    Energy Technology Data Exchange (ETDEWEB)

    Staynova, A.; Hadjidekova, V.; Popova, L.; Hristova, R.; Georgieva, G. [Radiation Genetics Laboratory, National Centre of Radiobology and Radiation Protection, Sofia (Bulgaria)

    2013-07-01

    The correct estimation of the possible genotoxic effects in humans after external damage agents exposures depends on the data of the spontaneous levels of the biomarkers used. Spontaneous levels of chromosomal aberrations (CA) and micronuclei (MN) formation in human peripheral lymphocytes, and their variability were studied in a population of a clean environmentally regions in Bulgaria. Spontaneous frequency of CA was investigated in peripheral blood lymphocytes of 151 subjects. Peripheral blood lymphocytes from 148 subjects were analysed for the presence of MN. Also MN assay was applied for evaluation of genotoxic effects in buccal epithelium cells obtained from 43 donors. The mean frequency ± sd of the cells with ca is 1.42± 0.95. The mean frequency ± SD of cells with MN is 11.99 ± 6.50%. The mean frequency ± SD of cells with MN in buccal epithelium cells was found to be 2.53 ± 1.41x10{sup -3}. (author)

  14. Heart PET scan

    Science.gov (United States)

    ... nuclear medicine scan; Heart positron emission tomography; Myocardial PET scan ... A PET scan requires a small amount of radioactive material (tracer). This tracer is given through a vein (IV), ...

  15. In-situ fluorescence hybridization applied to biological dosimetry: contribution of automation to the counting of radio-induced chromosome aberrations

    International Nuclear Information System (INIS)

    Germain Thomas Roy, Laurence

    1999-01-01

    The frequency of chromosome aberrations on peripheral blood lymphocytes is a dose indicator in the case of ionizing radiations over-exposure. Stable chromosome aberrations (translocations, insertions) are visualized after labelling of some chromosomes using the fluorescence in-situ hybridization (FISH). The study of the use of the FISH technique in biological dosimetry is done with dose-effect curves. It seems that a bias is introduced during the observation of chromosome aberrations involving only 3 pairs of chromosomes. In order to avoid this bias, it would be useful to test the feasibility of using the multi-FISH technique in biological dosimetry. Moreover, this type of chromosome aberration changes with the type of irradiation. It is thus important to define the aberrations to be considered when the FISH technique is used. In order to reduce the time of image analysis, the CYTOGEN system, developed by IMSTAR company (Paris, France) has been adapted to the needs of biological dosimetry. This system allows to localize automatically the metaphases on the slide, which reduces the observation time by 2 or 4. An automatic detection protocol for chromosome aberrations has been implemented. It comprises the image capture, the contours detection and the classification of some chromosome aberrations. The different steps of this protocol have been tested in order to check that no bias is introduced by the automation. However, because radio-induced aberrations are rare events, it seems that a totally automatic system is not foreseeable. A semi-automatic analysis is more suitable. The use of the Slit-Scan technology (Laboratory of applied physics, Heidelberg, Germany) in biological dosimetry has been studied too. This technique allows to analyze rapidly a huge number of chromosomes. A good correlation has been observed between the dicentric frequency measured automatically and by manual counting. The system is under development and should be adapted to the detection of

  16. A Rare Case of Esophageal Dysphagia in Children: Aberrant Right Subclavian Artery

    Directory of Open Access Journals (Sweden)

    Claudia Barone

    2016-01-01

    Full Text Available Dysphagia is an impairment of swallowing that may involve any structures from the mouth to the stomach. Esophageal dysphagia presents with the sensation of food sticking, pain with swallowing, substernal pressure, or chronic heartburn. There are many causes of esophageal dysphagia, such as motility disorders and mechanical and inflammatory diseases. Infrequently dysphagia arises from extrinsic compression of the esophagus from any vascular anomaly of the aortic arch. The most common embryologic abnormality of the aortic arch is aberrant right subclavian artery, clinically known as arteria lusoria. This abnormality is usually silent. Here, we report a case of six-year-old child presenting to us with a history of progressive dysphagia without respiratory symptoms. A barium esophagogram showed an increase of the physiological esophageal narrowing at the level of aortic arch, while at esophagogastroduodenoscopy there was an extrinsic pulsatile compression of the posterior portion of the esophagus suggesting an extrinsic compression by an aberrant vessel. Angio-CT (computed tomography scan confirmed the presence of an aberrant right subclavian artery.

  17. Application of the aberration ring test (ARTEMIS) to determine lens quality and predict its lithographic performance

    Science.gov (United States)

    Moers, Marco H. P.; van der Laan, Hans; Zellenrath, Mark; de Boeij, Wim; Beaudry, Neil A.; Cummings, Kevin D.; van Zwol, Adriaan; Brecht, Arthur; Willekers, Rob

    2001-09-01

    ARTEMISTM (Aberration Ring Test Exposed at Multiple Illumination Settings) is a technique to determine in-situ, full-field, low and high order lens aberrations. In this paper we are analyzing the ARTEMISTM data of PAS5500/750TM DUV Step & Scan systems and its use as a lithographic prediction tool. ARTEMISTM is capable of determining Zernike coefficients up to Z25 with a 3(sigma) reproducibility range from 1.5 to 4.5 nm depending on the aberration type. 3D electric field simulations, that take the extended geometry of the phase shift feature into account, have been used for an improved treatment of the extraction of the spherical Zernike coefficients. Knowledge of the extracted Zernike coefficients allows an accurate prediction of the lithographic performance of the scanner system. This ability is demonstrated for a two bar pattern and an isolation pattern. The RMS difference between the ARTEMISTM-based lithographic prediction and the lithographic measurement is 2.5 nm for the two bar pattern and 3 nm for the isolation pattern. The 3(sigma) reproducibility of the prediction for the two bar pattern is 2.5 nm and 1 nm for the isolation pattern. This is better than the reproducibility of the lithographic measurements themselves.

  18. Chromosome aberrations induced by radiation. With special reference to possible relation between chromosome aberrations and carcinogenesis

    Energy Technology Data Exchange (ETDEWEB)

    Kamada, N [Hiroshima Univ. (Japan). Research Inst. for Nuclear Medicine and Biology

    1980-02-01

    Chromosome aberration seems to be one of the most conspicuous residual abnormalities recognizable in radiation-exposed persons for many years after exposure. Knowledge of the biological significance of these abnormalities seems to be necessary for understanding of the effect of radiation on humans, especially in relation to possible leukemic development. Cytogenetic studies were performed on the bone marrow cells, T and B lymphocytes, and fibroblasts in atomic bomb-survivors who were in apparent good health (105 cases), atomic bomb exposed patients who had prolonged periods of blood disorders which terminated in acute leukemia (8 cases), and who had no such abnormalities (6 cases). All patients with chronic myelocytic leukemia (CML) and a history of atomic bomb exposure showed Philadelphia chromosome, a characteristic chromosome abnormality for CML. The persistent chromosome aberrations of bone marrow cells, T and B lymphocytes found among the atomic bomb survivors with or without blood disorders may give some clue to solve the problems of carcinogenesis.

  19. Fifth-order aberrations in magnetic quadrupole-octupole systems

    International Nuclear Information System (INIS)

    Ling, K.M.

    1990-01-01

    Explicit integral expressions are given for the fifth-order geometrical aberration coefficients in rectilinear magnetic quadrupole-octupole systems used for the transport of nonrelativistic charged particle beams. The numerical values of the fifth-order geometrical aberration coefficients for a rare earth cobalt (REC) quadrupole doublet are given as an example. 26 refs., 5 figs., 4 tabs

  20. An aberrant uterus: Case report | Ondieki | East African Medical ...

    African Journals Online (AJOL)

    A case of an aberrant uterus is presented and literature reviewed. The patient presented with abnormal uterine bleeding, left iliac fossa pain and was managed by excising the aberrant uterus. This case was an enigma as it didn't present in the classical way one with anomalies of the uterus would present. Despite ...

  1. Accuracy of modal wavefront estimation from eye transverse aberration measurements

    Science.gov (United States)

    Chyzh, Igor H.; Sokurenko, Vyacheslav M.

    2001-01-01

    The influence of random errors in measurement of eye transverse aberrations on the accuracy of reconstructing wave aberration as well as ametropia and astigmatism parameters is investigated. The dependence of mentioned errors on a ratio between the number of measurement points and the number of polynomial coefficients is found for different pupil location of measurement points. Recommendations are proposed for setting these ratios.

  2. Aberration analysis calculations for synchrotron radiation beamline design

    International Nuclear Information System (INIS)

    McKinney, W.R.; Howells, M.; Padmore, H.A.

    1997-09-01

    The application of ray deviation calculations based on aberration coefficients for a single optical surface for the design of beamline optical systems is reviewed. A systematic development is presented which allows insight into which aberration may be causing the rays to deviate from perfect focus. A new development allowing analytical calculation of line shape is presented

  3. Chromatic aberrations of two-electrode transaxial mirrors

    International Nuclear Information System (INIS)

    Bejzina, L.G.; Karetskaya, S.P.

    1991-01-01

    Second order chromatic aberrations of electrostatic two-electrode transaxial mirrors in case the beam axial trajectory of charged particles is curvilinear are considered. Interrelations between coefficients of linear and angular chromatic aberrations are determined. Values of these coefficients for concave and convex transaxial mirrors with plane electrodes in dependence on potential ratio on electrodes by different onnular clearance radii are presented

  4. Third-order monochromatic aberrations via Fermat's principle

    International Nuclear Information System (INIS)

    Marasco, A.; Romano, A.

    2006-01-01

    By Fermat's principle and particular optical paths, which are not rays, a new aberration function is introduced. This function allows to derive, without resorting to the whole Hamiltonian formalism, the third-order geometrical aberrations of an optical system with a symmetry of revolution

  5. Non-invasive transcranial ultrasound therapy based on a 3D CT scan: protocol validation and in vitro results

    International Nuclear Information System (INIS)

    Marquet, F; Pernot, M; Aubry, J-F; Montaldo, G; Tanter, M; Fink, M; Marsac, L

    2009-01-01

    A non-invasive protocol for transcranial brain tissue ablation with ultrasound is studied and validated in vitro. The skull induces strong aberrations both in phase and in amplitude, resulting in a severe degradation of the beam shape. Adaptive corrections of the distortions induced by the skull bone are performed using a previous 3D computational tomography scan acquisition (CT) of the skull bone structure. These CT scan data are used as entry parameters in a FDTD (finite differences time domain) simulation of the full wave propagation equation. A numerical computation is used to deduce the impulse response relating the targeted location and the ultrasound therapeutic array, thus providing a virtual time-reversal mirror. This impulse response is then time-reversed and transmitted experimentally by a therapeutic array positioned exactly in the same referential frame as the one used during CT scan acquisitions. In vitro experiments are conducted on monkey and human skull specimens using an array of 300 transmit elements working at a central frequency of 1 MHz. These experiments show a precise refocusing of the ultrasonic beam at the targeted location with a positioning error lower than 0.7 mm. The complete validation of this transcranial adaptive focusing procedure paves the way to in vivo animal and human transcranial HIFU investigations.

  6. Non-invasive transcranial ultrasound therapy based on a 3D CT scan: protocol validation and in vitro results

    Energy Technology Data Exchange (ETDEWEB)

    Marquet, F; Pernot, M; Aubry, J-F; Montaldo, G; Tanter, M; Fink, M [Laboratoire Ondes et Acoustique, ESPCI, Universite Paris VII, UMR CNRS 7587, 10 rue Vauquelin, 75005 Paris (France); Marsac, L [Supersonic Imagine, Les Jardins de la Duranne, 510 rue Rene Descartes, 13857 Aix-en-Provence (France)], E-mail: fabrice.marquet@espci.org

    2009-05-07

    A non-invasive protocol for transcranial brain tissue ablation with ultrasound is studied and validated in vitro. The skull induces strong aberrations both in phase and in amplitude, resulting in a severe degradation of the beam shape. Adaptive corrections of the distortions induced by the skull bone are performed using a previous 3D computational tomography scan acquisition (CT) of the skull bone structure. These CT scan data are used as entry parameters in a FDTD (finite differences time domain) simulation of the full wave propagation equation. A numerical computation is used to deduce the impulse response relating the targeted location and the ultrasound therapeutic array, thus providing a virtual time-reversal mirror. This impulse response is then time-reversed and transmitted experimentally by a therapeutic array positioned exactly in the same referential frame as the one used during CT scan acquisitions. In vitro experiments are conducted on monkey and human skull specimens using an array of 300 transmit elements working at a central frequency of 1 MHz. These experiments show a precise refocusing of the ultrasonic beam at the targeted location with a positioning error lower than 0.7 mm. The complete validation of this transcranial adaptive focusing procedure paves the way to in vivo animal and human transcranial HIFU investigations.

  7. Interchromosomal distribution of gamma ray-induced chromatid aberrations in Chinese hamster ovary cells

    International Nuclear Information System (INIS)

    Martinez-Lopez, Wilner; Porro, Valentina; Folle, Gustavo A.; Mendez-Acuna, Leticia; Obe, Guenter; Savage, John R.K.

    2000-01-01

    Inter chromosomal distributions of breakpoints from chromatid-type aberrations induced by gamma rays in Chinese hamster ovary cells were analyzed. In most chromosomes the distribution was as expected from chromosome lengths for simple breaks or the respective relative corrected length in case of exchanges. There were deviations from expectation in a few chromosomes for chromatid breaks, interchanges, intra-arm intra changes and inter-arm intra changes. Especially interesting are the results concerning chromosomes 2 and 8, which were more often involved in exchanges than expected. An 'exchange phenotype' for these chromosomes is proposed and possible explanations for the nonrandom distribution of chromosome breakpoints are presented. (author)

  8. On the benefit of the negative-spherical-aberration imaging technique for quantitative HRTEM

    International Nuclear Information System (INIS)

    Jia, C.L.; Houben, L.; Thust, A.; Barthel, J.

    2010-01-01

    Employing an aberration corrector in a high-resolution transmission electron microscope, the spherical aberration C S can be tuned to negative values, resulting in a novel imaging technique, which is called the negative C S imaging (NCSI) technique. The image contrast obtained with the NCSI technique is compared quantitatively with the image contrast formed with the traditional positive C S imaging (PCSI) technique. For the case of thin objects negative C S images are superior to positive C S images concerning the magnitude of the obtained contrast, which is due to constructive rather than destructive superposition of fundamental contrast contributions. As a consequence, the image signal obtained with a negative spherical aberration is significantly more robust against noise caused by amorphous surface layers, resulting in a measurement precision of atomic positions which is by a factor of 2-3 better at an identical noise level. The quantitative comparison of the two alternative C S -corrected imaging modes shows that the NCSI mode yields significantly more precise results in quantitative high-resolution transmission electron microscopy of thin objects than the traditional PCSI mode.

  9. Chromosome aberration analysis based on a beta-binomial distribution

    International Nuclear Information System (INIS)

    Otake, Masanori; Prentice, R.L.

    1983-10-01

    Analyses carried out here generalized on earlier studies of chromosomal aberrations in the populations of Hiroshima and Nagasaki, by allowing extra-binomial variation in aberrant cell counts corresponding to within-subject correlations in cell aberrations. Strong within-subject correlations were detected with corresponding standard errors for the average number of aberrant cells that were often substantially larger than was previously assumed. The extra-binomial variation is accomodated in the analysis in the present report, as described in the section on dose-response models, by using a beta-binomial (B-B) variance structure. It is emphasized that we have generally satisfactory agreement between the observed and the B-B fitted frequencies by city-dose category. The chromosomal aberration data considered here are not extensive enough to allow a precise discrimination between competing dose-response models. A quadratic gamma ray and linear neutron model, however, most closely fits the chromosome data. (author)

  10. Chromosomal aberrations in bone marrow of continuously irradiated rats

    Energy Technology Data Exchange (ETDEWEB)

    Chlebosky, O; Praslicka, M; Chlebovska, K [Univerzita P.J. Safarika, Kosice (Czechoslovakia). Prirodovedecka Fakulta

    1975-01-01

    Research on chromosomal aberrations of the bone marrow in continuously irradiated rats showed that chromosomal aberrations are a highly sensitive indicator of radiation injury. An increase in the chromosomal aberration frequency was already found on the 5th day at daily doses of 0.5 R, i.e. a 12% increase at a total dose of 25 R. In the steady-state stage at daily doses of 0.5; 1; 2.5 R, the number of chromosomal aberrations stabilized at values of about 20%; at daily doses of 5 and 10 R at values of 30.=., at daily doses of 53 R at 45%, at a daily dose of 82.5 R, the number of chromosomal aberrations increased to 55%.

  11. Image based method for aberration measurement of lithographic tools

    Science.gov (United States)

    Xu, Shuang; Tao, Bo; Guo, Yongxing; Li, Gongfa

    2018-01-01

    Information of lens aberration of lithographic tools is important as it directly affects the intensity distribution in the image plane. Zernike polynomials are commonly used for a mathematical description of lens aberrations. Due to the advantage of lower cost and easier implementation of tools, image based measurement techniques have been widely used. Lithographic tools are typically partially coherent systems that can be described by a bilinear model, which entails time consuming calculations and does not lend a simple and intuitive relationship between lens aberrations and the resulted images. Previous methods for retrieving lens aberrations in such partially coherent systems involve through-focus image measurements and time-consuming iterative algorithms. In this work, we propose a method for aberration measurement in lithographic tools, which only requires measuring two images of intensity distribution. Two linear formulations are derived in matrix forms that directly relate the measured images to the unknown Zernike coefficients. Consequently, an efficient non-iterative solution is obtained.

  12. Cell survival and radiation induced chromosome aberrations. Pt. 2

    International Nuclear Information System (INIS)

    Bauchinger, M.; Schmid, E.; Braselmann, H.

    1986-01-01

    Human peripheral lymphocytes were irradiated in whole blood with 0.5-4.0 Gy of 220 kVp X-rays and the frequency of chromosome aberrations was determined in 1st or 2nd division metaphases discriminated by fluorescence plus giemsa staining. Using the empirical distributions of aberrations among cells, cell survival and transmission of aberrations were investigated. Considering both daughter cells, we found that 20% of fragments and 55% of dicentrics or ring chromosomes are lost during the 1st cell division; i.e. cell survival rate from 1st to 2nd generation is mainly influenced by anaphase bridging of these two-hit aberrations. Cell survival to 2nd mitosis was calculated considering this situation and compared with the survival derived from the fraction of M1 cells without unstable aberrations. The resulting shouldered survival curves showed significantly different slopes, indicating that cell reproductive death is overestimated in the latter approach. (orig.)

  13. Brown's TRANSPORT up to third order aberration by artificial intelligence

    International Nuclear Information System (INIS)

    Xia Jiawen; Xie Xi; Qiao Qingwen

    1991-01-01

    Brown's TRANSPORT is a first and second order matrix multiplication computer program intended for the design of accelerator beam transport systems, neglecting the third order aberration. Recently a new method was developed to derive analytically any order aberration coefficients of general charged particle optic system, applicable to any practical systems, such as accelerators, electron microscopes, lithographs, etc., including those unknown systems yet to be invented. An artificial intelligence program in Turbo Prolog was implemented on IBM-PC 286 or 386 machine to generate automatically the analytical expression of any order aberration coefficients of general charged particle optic system. Based on this new method and technique, Brown's TRANSPORT is extended beyond the second order aberration effects by artificial intelligence, outputing automatically all the analytical expressions up to the third order aberration coefficients

  14. Brown's transport up to third order aberration by artificial intelligence

    International Nuclear Information System (INIS)

    Xia Jiawen; Xie Xi; Qiao Qingwen

    1992-01-01

    Brown's TRANSPORT is a first and second order matrix multiplication computer program intended for the design of accelerator beam transport systems, neglecting the third order aberration. Recently a new method was developed to derive analytically any order aberration coefficients of general charged particle optic system, applicable to any practical systems, such as accelerators, electron microscopes, lithographs, including those unknown systems yet to be invented. An artificial intelligence program in Turbo Prolog was implemented on IBM-PC 286 or 386 machine to generate automatically the analytical expression of any order aberration coefficients of general charged particle optic system. Based on this new method and technique, Brown's TRANSPORT is extended beyond the second order aberration effect by artificial intelligence, outputting automatically all the analytical expressions up to the third order aberration coefficients

  15. Reducing depth induced spherical aberration in 3D widefield fluorescence microscopy by wavefront coding using the SQUBIC phase mask

    Science.gov (United States)

    Patwary, Nurmohammed; Doblas, Ana; King, Sharon V.; Preza, Chrysanthe

    2014-03-01

    Imaging thick biological samples introduces spherical aberration (SA) due to refractive index (RI) mismatch between specimen and imaging lens immersion medium. SA increases with the increase of either depth or RI mismatch. Therefore, it is difficult to find a static compensator for SA1. Different wavefront coding methods2,3 have been studied to find an optimal way of static wavefront correction to reduce depth-induced SA. Inspired by a recent design of a radially symmetric squared cubic (SQUBIC) phase mask that was tested for scanning confocal microscopy1 we have modified the pupil using the SQUBIC mask to engineer the point spread function (PSF) of a wide field fluorescence microscope. In this study, simulated images of a thick test object were generated using a wavefront encoded engineered PSF (WFEPSF) and were restored using space-invariant (SI) and depth-variant (DV) expectation maximization (EM) algorithms implemented in the COSMOS software4. Quantitative comparisons between restorations obtained with both the conventional and WFE PSFs are presented. Simulations show that, in the presence of SA, the use of the SIEM algorithm and a single SQUBIC encoded WFE-PSF can yield adequate image restoration. In addition, in the presence of a large amount of SA, it is possible to get adequate results using the DVEM with fewer DV-PSFs than would typically be required for processing images acquired with a clear circular aperture (CCA) PSF. This result implies that modification of a widefield system with the SQUBIC mask renders the system less sensitive to depth-induced SA and suitable for imaging samples at larger optical depths.

  16. Wave aberrations in rhesus monkeys with vision-induced ametropias

    Science.gov (United States)

    Ramamirtham, Ramkumar; Kee, Chea-su; Hung, Li-Fang; Qiao-Grider, Ying; Huang, Juan; Roorda, Austin; Smith, Earl L.

    2007-01-01

    The purpose of this study was to investigate the relationship between refractive errors and high-order aberrations in infant rhesus monkeys. Specifically, we compared the monochromatic wave aberrations measured with a Shack-Hartman wavefront sensor between normal monkeys and monkeys with vision-induced refractive errors. Shortly after birth, both normal monkeys and treated monkeys reared with optically induced defocus or form deprivation showed a decrease in the magnitude of high-order aberrations with age. However, the decrease in aberrations was typically smaller in the treated animals. Thus, at the end of the lens-rearing period, higher than normal amounts of aberrations were observed in treated eyes, both hyperopic and myopic eyes and treated eyes that developed astigmatism, but not spherical ametropias. The total RMS wavefront error increased with the degree of spherical refractive error, but was not correlated with the degree of astigmatism. Both myopic and hyperopic treated eyes showed elevated amounts of coma and trefoil and the degree of trefoil increased with the degree of spherical ametropia. Myopic eyes also exhibited a much higher prevalence of positive spherical aberration than normal or treated hyperopic eyes. Following the onset of unrestricted vision, the amount of high-order aberrations decreased in the treated monkeys that also recovered from the experimentally induced refractive errors. Our results demonstrate that high-order aberrations are influenced by visual experience in young primates and that the increase in high-order aberrations in our treated monkeys appears to be an optical byproduct of the vision-induced alterations in ocular growth that underlie changes in refractive error. The results from our study suggest that the higher amounts of wave aberrations observed in ametropic humans are likely to be a consequence, rather than a cause, of abnormal refractive development. PMID:17825347

  17. Aberration-free intraocular lenses - What does this really mean?

    Science.gov (United States)

    Langenbucher, Achim; Schröder, Simon; Cayless, Alan; Eppig, Timo

    2017-09-01

    So-called aberration-free intraocular lenses (IOLs) are well established in modern cataract surgery. Usually, they are designed to perfectly refract a collimated light beam onto the focal point. We show how much aberration can be expected with such an IOL in a convergent light beam such as that found anterior to the human cornea. Additionally, the aberration in a collimated beam is estimated for an IOL that has no aberrations in the convergent beam. The convergent beam is modelled as the pencil of rays corresponding to the spherical wavefront resulting from a typical corneal power of 43m -1 . The IOLs are modelled as infinitely thin phase plates with 20m -1 optical power placed 5mm behind the cornea. Their aberrations are reported in terms of optical path length difference and longitudinal spherical aberration (LSA) of the marginal rays, as well as nominal spherical aberration (SA) calculated based on a Zernike representation of the wavefront-error at the corneal plane within a 6mm aperture. The IOL designed to have no aberrations in a collimated light beam has an optical path length difference of -1.8μm, and LSA of 0.15m -1 in the convergent beam of a typical eye. The corresponding nominal SA is 0.065μm. The IOL designed to have no aberrations in a convergent light beam has an optical path length difference of 1.8μm, and LSA of -0.15m -1 in the collimated beam. An IOL designed to have no aberrations in a collimated light beam will increase the SA of a patient's eye after implantation. Copyright © 2017. Published by Elsevier GmbH.

  18. An unusual case of left aberrant innominate artery with right aortic arch: evaluation with high-resolution CT

    Energy Technology Data Exchange (ETDEWEB)

    Calcagni, Giulio [University Rene Descartes-Paris 5, Department of Pediatric Cardiology, Hopital Necker Enfants Malades, Paris (France); Gesualdo, Francesco; Brunelle, Francis; Ou, Phalla [University Rene Descartes-Paris 5, Department of Pediatric Radiology, Hopital Necker Enfants Malades, Paris Cedex 15 (France)

    2008-01-15

    A left aberrant innominate (brachiocephalic) artery is an angiographically well-known entity that may cause tracheal compression. We report a male newborn who was admitted for further investigation of a prenatally suspected major vessel anomaly. High-resolution CT was used to completely assess the abnormal anatomy and the relationship with the airway, as well as to guide the surgical approach for its correction. (orig.)

  19. An unusual case of left aberrant innominate artery with right aortic arch: evaluation with high-resolution CT

    International Nuclear Information System (INIS)

    Calcagni, Giulio; Gesualdo, Francesco; Brunelle, Francis; Ou, Phalla

    2008-01-01

    A left aberrant innominate (brachiocephalic) artery is an angiographically well-known entity that may cause tracheal compression. We report a male newborn who was admitted for further investigation of a prenatally suspected major vessel anomaly. High-resolution CT was used to completely assess the abnormal anatomy and the relationship with the airway, as well as to guide the surgical approach for its correction. (orig.)

  20. Mathematical models for correction of images, obtained at radioisotope scan

    International Nuclear Information System (INIS)

    Glaz, A.; Lubans, A.

    2002-01-01

    The images, which obtained at radioisotope scintigraphy, contain distortions. Distortions appear as a result of absorption of radiation by patient's body's tissues. Two mathematical models for reducing of such distortions are proposed. Image obtained by only one gamma camera is used in the first mathematical model. Unfortunately, this model allows processing of the images only in case, when it can be assumed, that the investigated organ has a symmetric form. The images obtained by two gamma cameras are used in the second model. It gives possibility to assume that the investigated organ has non-symmetric form and to acquire more precise results. (authors)

  1. Higher-Order Wavefront Aberrations for Populations of Young Emmetropes and Myopes

    Directory of Open Access Journals (Sweden)

    Jinhua Bao

    2009-01-01

    Conclusions: Human eyes have systematical higher order aberrations in population, and factors that cause bilateral symmetry of wavefront aberrations between the right and left eyes made important contribution to the systematical aberrations.

  2. Universality of quantum gravity corrections.

    Science.gov (United States)

    Das, Saurya; Vagenas, Elias C

    2008-11-28

    We show that the existence of a minimum measurable length and the related generalized uncertainty principle (GUP), predicted by theories of quantum gravity, influence all quantum Hamiltonians. Thus, they predict quantum gravity corrections to various quantum phenomena. We compute such corrections to the Lamb shift, the Landau levels, and the tunneling current in a scanning tunneling microscope. We show that these corrections can be interpreted in two ways: (a) either that they are exceedingly small, beyond the reach of current experiments, or (b) that they predict upper bounds on the quantum gravity parameter in the GUP, compatible with experiments at the electroweak scale. Thus, more accurate measurements in the future should either be able to test these predictions, or further tighten the above bounds and predict an intermediate length scale between the electroweak and the Planck scale.

  3. Aberrant brain functional connectome in patients with obstructive sleep apnea.

    Science.gov (United States)

    Chen, Li-Ting; Fan, Xiao-Le; Li, Hai-Jun; Ye, Cheng-Long; Yu, Hong-Hui; Xin, Hui-Zhen; Gong, Hong-Han; Peng, De-Chang; Yan, Li-Ping

    2018-01-01

    Obstructive sleep apnea (OSA) is accompanied by widespread abnormal spontaneous regional activity related to cognitive deficits. However, little is known about the topological properties of the functional brain connectome of patients with OSA. This study aimed to use the graph theory approaches to investigate the topological properties and functional connectivity (FC) of the functional connectome in patients with OSA, based on resting-state functional magnetic resonance imaging (rs-fMRI). Forty-five male patients with newly diagnosed untreated severe OSA and 45 male good sleepers (GSs) underwent a polysomnography (PSG), clinical evaluations, and rs-fMRI scans. The automated anatomical labeling (AAL) atlas was used to construct the functional brain connectome. The topological organization and FC of brain functional networks in patients with OSA were characterized using graph theory methods and investigated the relationship between functional network topology and clinical variables. Both the patients with OSA and the GSs exhibited high-efficiency "small-world" network attributes. However, the patients with OSA exhibited decreased σ, γ, E glob ; increased Lp, λ; and abnormal nodal centralities in several default-mode network (DMN), salience network (SN), and central executive network (CEN) regions. However, the patients with OSA exhibited abnormal functional connections between the DMN, SN, and CEN. The disrupted FC was significantly positive correlations with the global network metrics γ and σ. The global network metrics were significantly correlated with the Epworth Sleepiness Scale (ESS) score, Montreal Cognitive Assessment (MoCA) score, and oxygen desaturation index. The findings suggest that the functional connectome of patients with OSA exhibited disrupted functional integration and segregation, and functional disconnections of the DMN, SN, and CEN. The aberrant topological attributes may be associated with disrupted FC and cognitive functions. These

  4. The Mechanisms of Aberrant Protein Aggregation

    Science.gov (United States)

    Cohen, Samuel; Vendruscolo, Michele; Dobson, Chris; Knowles, Tuomas

    2012-02-01

    We discuss the development of a kinetic theory for understanding the aberrant loss of solubility of proteins. The failure to maintain protein solubility results often in the assembly of organized linear structures, commonly known as amyloid fibrils, the formation of which is associated with over 50 clinical disorders including Alzheimer's and Parkinson's diseases. A true microscopic understanding of the mechanisms that drive these aggregation processes has proved difficult to achieve. To address this challenge, we apply the methodologies of chemical kinetics to the biomolecular self-assembly pathways related to protein aggregation. We discuss the relevant master equation and analytical approaches to studying it. In particular, we derive the underlying rate laws in closed-form using a self-consistent solution scheme; the solutions that we obtain reveal scaling behaviors that are very generally present in systems of growing linear aggregates, and, moreover, provide a general route through which to relate experimental measurements to mechanistic information. We conclude by outlining a study of the aggregation of the Alzheimer's amyloid-beta peptide. The study identifies the dominant microscopic mechanism of aggregation and reveals previously unidentified therapeutic strategies.

  5. The Compact Hyperspectral Aberration-corrected Platform (CHAP), an instrument for microspacecraft., Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — In-situ analysis of solar system bodies plays a crucial role in understanding the evolution of our planet, setting the stage for life's origins. As has been...

  6. The Compact Hyperspectral Aberration-Corrected Platform (CHAP), an Instrument for Microspacecraft., Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — In-situ analysis of solar system bodies plays a crucial role in understanding the evolution of our planet, setting the stage for life's origins. As has been...

  7. Chromatic aberration correction and deconvolution for UV sensitive imaging of fluorescent sterols in cytoplasmic lipid droplets

    DEFF Research Database (Denmark)

    Wüstner, Daniel; Faergeman, Nils J

    2008-01-01

    adipocyte differentiation. DHE is targeted to transferrin-positive recycling endosomes in preadipocytes but associates with droplets in mature adipocytes. Only in adipocytes but not in foam cells fluorescent sterol was confined to the droplet-limiting membrane. We developed an approach to visualize...... macrophage foam cells and in adipocytes. We used deconvolution microscopy and developed image segmentation techniques to assess the DHE content of lipid droplets in both cell types in an automated manner. Pulse-chase studies and colocalization analysis were performed to monitor the redistribution of DHE upon...

  8. Cellular origin of prognostic chromosomal aberrations in AML patients

    DEFF Research Database (Denmark)

    Mora-Jensen, H.; Jendholm, J.; Rapin, N.

    2015-01-01

    chromosomal structural rearrangements and single nucleotide variants (SNVs). Conventional AML diagnostics and recent seminal next-generation sequencing (NGS) studies have identified more than 200 recurrent genetic aberrations presenting in various combinations in individual patients. Significantly, many...... of these aberrations occur in normal hematopoietic stem and progenitor cells (HSCs/HPCs) before definitive leukemic transformation through additional acquisition of a few (that is, mostly 1 or 2) leukemia-promoting driver aberrations. NGS studies on sorted bone marrow (BM) populations of AML patients with a normal...

  9. Chromosome aberrations analysis of Serbia population from 1985 to 1995

    International Nuclear Information System (INIS)

    Jovicic, D.; Markovic, B.; Milacic, S.; Joksic, G.

    1996-01-01

    After the accident of NE Chernobyl in May 1986, Chernobyl's fallout with unhomogeneous dispersion of radioactive material in atmosphere caused the difference in contamination of the Serbia territory. The highest contamination was found to be in region Uzice, and the lowest in the region Nis. Two groups of population from these regions were undergone chromosome aberration analysis during 1987, 1988 and 1989. year. The results of our examination show increased frequency of structural chromosome aberrations/dicentrics, rings, peri centric inversions and acentric/ in the Uzice population, especially in the 1987. year. In 1985 and 1995 year have not been found chromosome aberrations. 2 refs.; 1 figs.; 2 tabs

  10. Aberrant expression of HMB-45 in traumatized melanocytic nevi.

    Science.gov (United States)

    Leleux, Todd M; Prieto, Victor G; Diwan, A Hafeez

    2012-09-01

    Assessment of histologic and immunohistochemical maturation (with HMB-45 and anti-Ki-67) may be helpful in differentiating benign melanocytic nevi (BMN) from malignant melanoma. Recently, we reported loss of maturation and aberrant immunohistochemical findings in melanocytic nevi after liquid nitrogen cryotherapy (Adeniran et al, J Am Acad Dermatol 2009;61:341-5). Herein we report a similar phenomenon identified in traumatized melanocytic nevi (TMN). We sought to evaluate the histologic and immunohistochemical findings in early and late stages of traumatized nevi. Twenty-four cases of TMN were retrieved from the pathology archives. These were then assessed by two pathologists (T.L. and A.H.D.) using HMB-45 and MIB-1 (for Ki-67) antibodies. TMN showed some of the following findings: epidermal changes (parakeratosis, ulceration, serum crust, flattening of the epidermis) and dermal changes including fibrosis and the presence of melanophages. In some cases, there was architectural disorder of the overlying melanocytes, with crowding in the basal layer, but without significant pagetoid spread. Occasionally, the dermal scar contained larger, more epithelioid-appearing melanocytes than those beneath the scar. Fifty-four percent of TMN lacked obvious immunohistochemical maturation with HMB-45, since nevus cells within the scar or directly beneath it were strongly labeled. None of the TMN showed appreciable labeling for Ki-67. The exact clinical duration between trauma and biopsy could not be determined. Loss of maturation with HMB-45 in TMN can be a diagnostic pitfall in challenging cases. Concurrent evaluation of MIB-1 expression, along with the characteristic histologic features of trauma, should allow the correct diagnosis to be reached. Copyright © 2011 American Academy of Dermatology, Inc. Published by Mosby, Inc. All rights reserved.

  11. Computer-assisted detection of chromosomal aberrations for the purpose of establishing a biological dosimeter

    International Nuclear Information System (INIS)

    Ueberreiter, B.

    1982-01-01

    Using a special high-resolution microscopy apparatus, digital light microscope images of human chromosomes were generated, and specific image processing algorithms were developed. The pattern recognition process for computer-assisted detection of specific, radiation-induced chromosomal aberrations comprises three steps: First, the orientation of the segmented objects is defined and corrected. For date reduction purposes, the individual chromosomes are reduced to a few basic types containing typical information. After a linear transformation step, the characteristic parameters thus derived form a parameter vector for statistical classification. The method was well suited for distinguishing normal chromosomes from chromosomal aberrations. 94% of the objects were identified correctly. To achieve even higher accuracy, quality standards were set by which suspectedly misclassified objects can be re-investigated in dialog by the human observer. Implementation of the program system for parameter extraction on a fast polyprocessor system opens up a realistic chance of reducing the computing time for dose estimates to about one hour. (orig./MG) [de

  12. Radiopharmaceutical scanning agents

    International Nuclear Information System (INIS)

    1976-01-01

    This invention is directed to dispersions useful in preparing radiopharmaceutical scanning agents, to technetium labelled dispersions, to methods for preparing such dispersions and to their use as scanning agents

  13. Thyroid Scan and Uptake

    Medline Plus

    Full Text Available ... Scan and Uptake Thyroid scan and uptake uses small amounts of radioactive materials called radiotracers, a special ... is a branch of medical imaging that uses small amounts of radioactive material to diagnose and determine ...

  14. Nuclear Heart Scan

    Science.gov (United States)

    ... Home / Nuclear Heart Scan Nuclear Heart Scan Also known as Nuclear Stress Test , ... Learn More Connect With Us Contact Us Directly Policies Privacy Policy Freedom of Information Act (FOIA) Accessibility ...

  15. Thyroid Scan and Uptake

    Medline Plus

    Full Text Available ... of page What will I experience during and after the procedure? Most thyroid scan and thyroid uptake ... you otherwise, you may resume your normal activities after your nuclear medicine scan. If any special instructions ...

  16. RBC nuclear scan

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/article/003835.htm RBC nuclear scan To use the sharing features on this page, please enable JavaScript. An RBC nuclear scan uses small amounts of radioactive material to ...

  17. Scanning gamma camera

    International Nuclear Information System (INIS)

    Engdahl, L.W.; Batter, J.F. Jr.; Stout, K.J.

    1977-01-01

    A scanning system for a gamma camera providing for the overlapping of adjacent scan paths is described. A collimator mask having tapered edges provides for a graduated reduction in intensity of radiation received by a detector thereof, the reduction in intensity being graduated in a direction normal to the scanning path to provide a blending of images of adjacent scan paths. 31 claims, 15 figures

  18. Aberration changes of the corneal anterior surface following discontinued use of rigid gas permeable contact lenses

    Directory of Open Access Journals (Sweden)

    Shi-Qi Dong

    2013-04-01

    Full Text Available AIM: To record aberrations with a corneal topographic device on the anterior surface of the cornea at different time-points prior to wearing and following discontinued use of rigid gas permeable (RGP contact lenses. The effect of wearing RGP on the anterior surface of the cornea was discussed to provide guidance for clinical refractive error correction. METHODS: The study objects were 24 eyes from 24 patients. All patients underwent identical examination procedures prior to lens use, as well as afterwards, including slit-lamp examination, non-contact tonometer measurement, computer optometry and corneal curvature measurement, subjective refraction test, and corneal topography analysis. The patients wore contact lenses everyday for 1 month and then discontinued. Corneal topographies were recorded at certain time points of 30 minutes, 1 day, 3, 7 and 14 days following use. RESULTS: Total corneal aberration at each time point following discontinued use of RGP contact lenses was less than the time point prior to use. Detailed results were as follows:root mean square (RMS (pre=(1.438±0.328μm, RMS (30 minutes=(1.076±0.355μm, RMS (1 day=(1.362±0.402μm, RMS (3 days=(1.373±0.398μm, RMS (7 days=(1.387±0.415μm, and RMS (14 days=(1.430±0.423μm. Results showed that at 30 minutes after discontinued use of RGP contact lenses, almost all 2nd- and 3rd-order aberrations change. Quadrafoil Z10 and spherical Z12 of the 4th-order were also changed. Alterations to Z5, Z6, and Z12 at 1 day after discontinued use were significant differences compared with the time period prior to RGP use:Z5 and Z6 decreased, and Z12 increased slightly. Z5 and Z6 remained decreased at 3 days after discontinued use, but Z9 and Z10 continued to increase and Z12 returned to levels prior to RGP use. At 14 days after discontinued use, all aberrations were not significantly different from the values prior to use. CONCLUSION: The use RGP contact lenses greatly reduced total

  19. Chromosome aberration studies and microdosimetry with radiations of varying quality

    International Nuclear Information System (INIS)

    Grillmaier, R.E.; Bihy, L.; Menzel, H.G.; Schuhmacher, H.

    1978-01-01

    To investigate the biological effectivity of complex irradiation fields encountered in radiation protection and high LET radiation therapy and to find meaningful specification of radiation quality closely related to the biological effectivity, correlated chromosome aberration studies and microdosimetric investigations have been carried out using cyclotron produced collimated fast neutrons. Human lymphocytes have been irradiated at different dose levels in the direct beam and in different positions in the penumbra and the rates of acentric fragments and dicentrics have been determined. In identical positions microdosimetric measurements have been performed. The dose relationship of aberration rates after irradiation in the direct beam, the aberration rates observed in the penumbra and the microdosimetric quantities ysub(D), ysub(F) and y* are presented and their relations are discussed. Furthermore the dose relationship of chromosome aberrations induced by 60 Co-γ-rays has been investigated and used to establish the RBE dose relationship of cyclotron neutrons

  20. Chromosome aberrations in pesticide-exposed greenhouse workers

    DEFF Research Database (Denmark)

    Lander, B F; Knudsen, Lisbeth E.; Gamborg, M O

    2000-01-01

    OBJECTIVES: The aim of this study was to investigate the possibility of subtoxic exposure to pesticides causing chromosome aberrations in greenhouse workers. METHODS: In a cross-sectional and prospective study design chromosome aberration frequencies in cultured lymphocytes were examined for 116...... greenhouse workers exposed to a complex mixture of almost 50 insecticides, fungicides, and growth regulators and also for 29 nonsmoking, nonpesticide-exposed referents. RESULTS: The preseason frequencies of chromosome aberrations were slightly but not statistically significantly elevated for the greenhouse...... workers when they were compared with the referents. After a summer season of pesticide spraying in the greenhouses, the total frequencies of cells with chromosome aberrations were significantly higher than in the preseason samples (P=0.02) and also higher than for the referents (P=0.05). This finding...

  1. Aberrant Chromatin Modification as a Mechanism of Prostate Cancer Progression

    National Research Council Canada - National Science Library

    Chen, Hongwu

    2004-01-01

    .... However, the underlying mechanism is still unclear. The purpose of this study is to test the hypothesis that aberrant chromatin modification plays a critical role in prostate cancer progression...

  2. Aberrant internal carotid artery in the middle ear

    Energy Technology Data Exchange (ETDEWEB)

    Roh, Keun Tak; Kang, Hyun Koo [Dept. of Radiology, Seoul Veterans Hospital, Seoul (Korea, Republic of)

    2014-10-15

    The knowledge about the aberrant internal carotid artery (ICA) in the middle ear is essential for clinicians, because a misdiagnosis of the aberrant ICA could have serious consequences such as excessive aural bleeding during a middle ear surgery. A 38-year-old woman presented with tinnitus and hearing difficulties of the left ear that had started 5 years ago. During otoscopy, an anteroinferior bluish mass was seen in the tympanic space. Computed tomography and magnetic resonance imaging demonstrated a left-side aberrant ICA with bony dehiscence of the carotid canal in the middle ear and a reduced diameter of the tympanic ICA. Herein we report a case of an aberrant ICA in the middle ear. We also review the literature regarding this important vascular anomaly of the temporal bone which may lead to disastrous surgical complications.

  3. Aberrant internal carotid artery in the middle ear

    International Nuclear Information System (INIS)

    Roh, Keun Tak; Kang, Hyun Koo

    2014-01-01

    The knowledge about the aberrant internal carotid artery (ICA) in the middle ear is essential for clinicians, because a misdiagnosis of the aberrant ICA could have serious consequences such as excessive aural bleeding during a middle ear surgery. A 38-year-old woman presented with tinnitus and hearing difficulties of the left ear that had started 5 years ago. During otoscopy, an anteroinferior bluish mass was seen in the tympanic space. Computed tomography and magnetic resonance imaging demonstrated a left-side aberrant ICA with bony dehiscence of the carotid canal in the middle ear and a reduced diameter of the tympanic ICA. Herein we report a case of an aberrant ICA in the middle ear. We also review the literature regarding this important vascular anomaly of the temporal bone which may lead to disastrous surgical complications.

  4. Establishing working standards of chromosome aberrations analysis for biological dosimetry

    International Nuclear Information System (INIS)

    Bui Thi Kim Luyen; Tran Que; Pham Ngoc Duy; Nguyen Thi Kim Anh; Ha Thi Ngoc Lien

    2015-01-01

    Biological dosimetry is an dose assessment method using specify bio markers of radiation. IAEA (International Atomic Energy Agency) and ISO (International Organization for Standardization) defined that dicentric chromosome is specify for radiation, it is a gold standard for biodosimetry. Along with the documents published by IAEA, WHO, ISO and OECD, our results of study on the chromosome aberrations induced by radiation were organized systematically in nine standards that dealing with chromosome aberration test and micronucleus test in human peripheral blood lymphocytes in vitro. This standard addresses: the reference dose-effect for dose estimation, the minimum detection levels, cell culture, slide preparation, scoring procedure for chromosome aberrations use for biodosimetry, the criteria for converting aberration frequency into absorbed dose, reporting of results. Following these standards, the automatic analysis devices were calibrated for improving biological dosimetry method. This standard will be used to acquire and maintain accreditation of the Biological Dosimetry laboratory in Nuclear Research Institute. (author)

  5. Low level dose induced chromosome aberrations in human blood lymphocytes

    International Nuclear Information System (INIS)

    Pohl-Rueling, J.

    1992-01-01

    Unstable structural aberrations in chromosomes of human blood lymphocytes cannot be used as biological dosemeters in the low dose range, when extrapolating from high doses using a linear dose response, as required by the original formula of the dual radiation action theory. A survey is given of experimental dose-response curves of chromosome aberrations, obtained in investigations not only by this institute, in cooperation with many other laboratories, but also by various authors in different areas of the world. The results are not compatible with the predicted linear dose relationships at in vivo dose ranges up to 30 mGy.y -1 . The aberration frequencies rise sharply with dose within the normal environmental exposure up to about twice that level. At higher doses, aberration frequencies increase less rapidly and reach a plateau. Some in vitro experiments of various authors with higher doses of low LET radiations, up to about 400 mGy have found dose responses with steps. (author)

  6. Electron Optics for Biologists: Physical Origins of Spherical Aberrations

    Science.gov (United States)

    Geissler, Peter; Zadunaisky, Jose

    1974-01-01

    Reports on the physical origins of spherical aberrations in axially symmetric electrostatic lenses to convey the essentials of electon optics to those who must think critically about the resolution of the electron microscope. (GS)

  7. Zernike phase spatial filter for measuring the aberrations

    OpenAIRE

    Svetlana N. Khonina; Victor V. Kotlyar; Dmitriy V. Kirsh

    2015-01-01

    To measure directly the wavefront aberration coefficients, we propose to use the multi8order diffractive element fitted with the set of Zernike polynomials. Polynomials of lowest degree describe defocusing (ametropy) and astigmatism. Coefficients of highest degree correspond to the spherical aberration of oblique rays that occurs as a consequence of misalignment of the crystalline lens and foveola, as well as deflection at the periphery of the crystalline lens. Mul^order elements allow severa...

  8. Aberrant alternative splicing is another hallmark of cancer.

    Science.gov (United States)

    Ladomery, Michael

    2013-01-01

    The vast majority of human genes are alternatively spliced. Not surprisingly, aberrant alternative splicing is increasingly linked to cancer. Splice isoforms often encode proteins that have distinct and even antagonistic properties. The abnormal expression of splice factors and splice factor kinases in cancer changes the alternative splicing of critically important pre-mRNAs. Aberrant alternative splicing should be added to the growing list of cancer hallmarks.

  9. Aberrant Alternative Splicing Is Another Hallmark of Cancer

    OpenAIRE

    Ladomery, Michael

    2013-01-01

    The vast majority of human genes are alternatively spliced. Not surprisingly, aberrant alternative splicing is increasingly linked to cancer. Splice isoforms often encode proteins that have distinct and even antagonistic properties. The abnormal expression of splice factors and splice factor kinases in cancer changes the alternative splicing of critically important pre-mRNAs. Aberrant alternative splicing should be added to the growing list of cancer hallmarks.

  10. Aberrant Recapitulation of Developmental Program: Novel Target in Scleroderma

    Science.gov (United States)

    2015-12-01

    AWARD NUMBER: W81XWH-12-1-0472 TITLE: “Aberrant Recapitulation of Developmental Program: Novel Target in Scleroderma ” PRINCIPAL INVESTIGATOR...SUBTITLE Aberrant Recapitulation of Developmental Program: Novel Target in Scleroderma 5a. CONTRACT NUMBER W81XWH-12-1-0472 5b. GRANT NUMBER 5c. PROGRAM...SPONSOR/MONITOR’S REPORT NUMBER(S) 12. DISTRIBUTION / AVAILABILITY STATEMENT 13. SUPPLEMENTARY NOTES 14. ABSTRACT Fibrosis in scleroderma is associated

  11. Corrective Jaw Surgery

    Medline Plus

    Full Text Available ... and Craniofacial Surgery Cleft Lip/Palate and Craniofacial Surgery A cleft lip may require one or more ... find out more. Corrective Jaw Surgery Corrective Jaw Surgery Orthognathic surgery is performed to correct the misalignment ...

  12. Dimensions of driving anger and their relationships with aberrant driving.

    Science.gov (United States)

    Zhang, Tingru; Chan, Alan H S; Zhang, Wei

    2015-08-01

    The purpose of this study was to investigate the relationship between driving anger and aberrant driving behaviours. An internet-based questionnaire survey was administered to a sample of Chinese drivers, with driving anger measured by a 14-item short Driving Anger Scale (DAS) and the aberrant driving behaviours measured by a 23-item Driver Behaviour Questionnaire (DBQ). The results of Confirmatory Factor Analysis demonstrated that the three-factor model (hostile gesture, arrival-blocking and safety-blocking) of the DAS fitted the driving anger data well. The Exploratory Factor Analysis on DBQ data differentiated four types of aberrant driving, viz. emotional violation, error, deliberate violation and maintaining progress violation. For the anger-aberration relation, it was found that only "arrival-blocking" anger was a significant positive predictor for all four types of aberrant driving behaviours. The "safety-blocking" anger revealed a negative impact on deliberate violations, a finding different from previously established positive anger-aberration relation. These results suggest that drivers with different patterns of driving anger would show different behavioural tendencies and as a result intervention strategies may be differentially effective for drivers of different profiles. Copyright © 2015 Elsevier Ltd. All rights reserved.

  13. Multifocal multiphoton microscopy with adaptive optical correction

    Science.gov (United States)

    Coelho, Simao; Poland, Simon; Krstajic, Nikola; Li, David; Monypenny, James; Walker, Richard; Tyndall, David; Ng, Tony; Henderson, Robert; Ameer-Beg, Simon

    2013-02-01

    Fluorescence lifetime imaging microscopy (FLIM) is a well established approach for measuring dynamic signalling events inside living cells, including detection of protein-protein interactions. The improvement in optical penetration of infrared light compared with linear excitation due to Rayleigh scattering and low absorption have provided imaging depths of up to 1mm in brain tissue but significant image degradation occurs as samples distort (aberrate) the infrared excitation beam. Multiphoton time-correlated single photon counting (TCSPC) FLIM is a method for obtaining functional, high resolution images of biological structures. In order to achieve good statistical accuracy TCSPC typically requires long acquisition times. We report the development of a multifocal multiphoton microscope (MMM), titled MegaFLI. Beam parallelization performed via a 3D Gerchberg-Saxton (GS) algorithm using a Spatial Light Modulator (SLM), increases TCSPC count rate proportional to the number of beamlets produced. A weighted 3D GS algorithm is employed to improve homogeneity. An added benefit is the implementation of flexible and adaptive optical correction. Adaptive optics performed by means of Zernike polynomials are used to correct for system induced aberrations. Here we present results with significant improvement in throughput obtained using a novel complementary metal-oxide-semiconductor (CMOS) 1024 pixel single-photon avalanche diode (SPAD) array, opening the way to truly high-throughput FLIM.

  14. Isochronicity correction in the CR storage ring

    International Nuclear Information System (INIS)

    Litvinov, S.; Toprek, D.; Weick, H.; Dolinskii, A.

    2013-01-01

    A challenge for nuclear physics is to measure masses of exotic nuclei up to the limits of nuclear existence which are characterized by low production cross-sections and short half-lives. The large acceptance Collector Ring (CR) [1] at FAIR [2] tuned in the isochronous ion-optical mode offers unique possibilities for measuring short-lived and very exotic nuclides. However, in a ring designed for maximal acceptance, many factors limit the resolution. One point is a limit in time resolution inversely proportional to the transverse emittance. But most of the time aberrations can be corrected and others become small for large number of turns. We show the relations of the time correction to the corresponding transverse focusing and that the main correction for large emittance corresponds directly to the chromaticity correction for transverse focusing of the beam. With the help of Monte-Carlo simulations for the full acceptance we demonstrate how to correct the revolution times so that in principle resolutions of Δm/m=10 −6 can be achieved. In these calculations the influence of magnet inhomogeneities and extended fringe fields are considered and a calibration scheme also for ions with different mass-to-charge ratio is presented

  15. Construction of special eye models for investigation of chromatic and higher-order aberrations of eyes.

    Science.gov (United States)

    Zhai, Yi; Wang, Yan; Wang, Zhaoqi; Liu, Yongji; Zhang, Lin; He, Yuanqing; Chang, Shengjiang

    2014-01-01

    An achromatic element eliminating only longitudinal chromatic aberration (LCA) while maintaining transverse chromatic aberration (TCA) is established for the eye model, which involves the angle formed by the visual and optical axis. To investigate the impacts of higher-order aberrations on vision, the actual data of higher-order aberrations of human eyes with three typical levels are introduced into the eye model along visual axis. Moreover, three kinds of individual eye models are established to investigate the impacts of higher-order aberrations, chromatic aberration (LCA+TCA), LCA and TCA on vision under the photopic condition, respectively. Results show that for most human eyes, the impact of chromatic aberration on vision is much stronger than that of higher-order aberrations, and the impact of LCA in chromatic aberration dominates. The impact of TCA is approximately equal to that of normal level higher-order aberrations and it can be ignored when LCA exists.

  16. Induction of chromosomal aberrations in human lymphocytes by fission neutrons

    International Nuclear Information System (INIS)

    Silva, Marcia Augusta da; Coelho, Paulo Rogerio Pinto; Bartolini, Paolo; Okazaki, Kayo

    2009-01-01

    Chromosome aberrations induced by sparsely ionizing radiation (low-LET) are well known and cytogenetic analyses of irradiated human lymphocytes have been widely applied to biological dosimetry. However, much less is known about chromosome aberrations induced by densely ionizing radiation (high LET), such as that of alpha particles or neutrons. Such particles induce DNA strand breaks, as well as chromosome breakage and rearrangements of high complexity. This damage is more localized and less efficiently repaired than after X- or γ-ray irradiation. This preferential production of complex aberrations by densely ionizing radiation is related to the unique energy deposition patterns, which produces highly localized multiple DNA damage at the chromosomal level. A better knowledge of the interactions between different types of radiation and cellular DNA is of importance, not only from the radiobiological viewpoint but also for dosimetric and therapeutic purposes. The objective of the present study was to analyse the cytogenetic effects of fission neutrons on peripheral blood lymphocytes in order to evaluate structural and numerical aberrations and number of cells in the different mitotic cycles. So, blood samples from five healthy donors, 22-25 years old, of both sexes, were irradiated in the Research Reactor IEA-R1 of our Institute (IPEN/CNEN-SP) with thermal and fast neutrons at doses of 0.2; 0.3; 0.5 and 1.0 Gy. The γ contribution to the total absorbed dose was about 30%. These doses were monitored by thermoluminescent dosemeters: LiF-600 (for neutrons) and LiF-700 (for γ-rays). The data concerning structural aberrations were evaluated with regard to three parameters: percentage of cells with aberrations, number of aberrations/cell and number of dicentric/cell. The cytogenetic results showed an increase in the three parameters after irradiation with neutrons, as a function of radiation dose. Apparently, there was no influence of neutrons on the kinetics of cellular

  17. Current estimate of functional vision in patients with bifocal pseudophakia after correction of residual defocus by different methods

    Directory of Open Access Journals (Sweden)

    Yuri V Takhtaev

    2016-03-01

    Full Text Available In this article we evaluated the influence of different surgical methods for correction of residual ametropia on contrast sensitivity at different light conditions and high-order aberrations in patients with bifocal pseudophakia. The study included 45 eyes (30 people after cataract surgery, which studied dependence between contrast sensitivity and aberrations level before and after surgical correction of residual ametropia by of three methods - LASIK, Sulcoflex IOL implantation or IOL exchange. Contrast sensitivity was measured by Optec 6500 and aberration using Pentacam «OCULUS». We processed the results using the Mann-Whitney U-test. This study shows correlation between each method and residual aberrations level and their influence on contrast sensitivity level.

  18. High-resolution study of photoinduced modification in fused silica produced by a tightly focused femtosecond laser beam in the presence of aberrations

    International Nuclear Information System (INIS)

    Hnatovsky, C.; Taylor, R.S.; Simova, E.; Bhardwaj, V.R.; Rayner, D.M.; Corkum, P.B.

    2005-01-01

    An ultrahigh-resolution (20 nm) technique of selective chemical etching and atomic force microscopy has been used to study the photoinduced modification in fused silica produced at various depths by tightly focused femtosecond laser radiation affected by spherical aberration. We demonstrate that shapes of the irradiated zones near the threshold for modification can be predicted by taking proper account of spherical aberration caused by the refractive index mismatched air-silica interface. We establish a depth dependence of the pulse energy required to initiate modification and characterize the relationship between numerical aperture of the writing lens and practically achievable writing depth. We also show that spatial characteristics of the laser-modified zones can be controlled by a specially designed focusing system which allows correction for a variable amount of spherical aberration

  19. Lung PET scan

    Science.gov (United States)

    ... Chest PET scan; Lung positron emission tomography; PET - chest; PET - lung; PET - tumor imaging; ... Grainger & Allison's Diagnostic Radiology: A Textbook of Medical Imaging . 6th ed. Philadelphia, ...

  20. Scanning of bone metastases

    International Nuclear Information System (INIS)

    Robillard, J.

    1977-01-01

    The Centers against cancer of Caen, Angers, Montpellier, Strasbourg and 'the Curie Foundation' have confronted their experience in detection of bone metastases by total body scanning. From the investigation by this procedure, of 1,467 patients with cancer, it results: the confrontation between radio and scanning shows a rate of false positive and false negative identical to the literature ones; the countage scanning allows to reduce the number of false positive; scanning allows to direct bone biopsy and to improve efficiency of histological examination [fr

  1. Ionizing radiation and frequency of chromosomal aberrations in exposed personnel

    International Nuclear Information System (INIS)

    Spasojevic-Tisma, Vera; Pavlovic, Snezana

    2008-01-01

    Full text: Frequencies of chromosomal aberrations in lymphocytes of peripheral blood were investigated among the observed groups of subjects who were exposed to low radiation doses (external exposure) in comparison with the control group. The first group of subjects is involved in the production of radioisotope technetium, whose accumulated work exposure time ranges between 3 and 30 years. The second group works on inspection of the medical X-ray equipment, whose accumulated work exposure time is between 2 and 34 years. The third group worked on decontamination of the terrain from depleted uranium radioactive ammunition. These workers were involved in mechanical removal of the surface soil layer to a depth of 50 cm. They were selected out of a group of professionals otherwise exposed to radiation from confined sources in their daily work. The accumulated work exposure of this group ranged from 2 to 34 years. The control group consisted of individuals not working in the ionizing radiation zone. The average yearly absorbed dose measured by TL dosimeters for all three observed groups did not exceed 2 mSv. The chromosomal aberrations were analyzed by a modified Moorhead method. The objective of the study was to establish the existence of differences in the frequencies of chromosomal aberrations change with respect to the source type, i.e. type of radioactive emission. Comparisons of the chromosomal changes in the observed groups revealed that the group working on technetium production had an increase in the frequency of chromosomal aberrations with respect to control. The aberrations found were of the acentric fragment and chromosomal break types. A comparison of the exposed groups between each other, no statistically significant differences in the numbers of chromosomal aberrations were found. Soil decontamination from depleted uranium did not contribute to the relative radiation risk, since it lasted only a few months, and was done by the professionals fully clothed

  2. Aberrant neural networks for the recognition memory of socially relevant information in patients with schizophrenia.

    Science.gov (United States)

    Oh, Jooyoung; Chun, Ji-Won; Kim, Eunseong; Park, Hae-Jeong; Lee, Boreom; Kim, Jae-Jin

    2017-01-01

    Patients with schizophrenia exhibit several cognitive deficits, including memory impairment. Problems with recognition memory can hinder socially adaptive behavior. Previous investigations have suggested that altered activation of the frontotemporal area plays an important role in recognition memory impairment. However, the cerebral networks related to these deficits are not known. The aim of this study was to elucidate the brain networks required for recognizing socially relevant information in patients with schizophrenia performing an old-new recognition task. Sixteen patients with schizophrenia and 16 controls participated in this study. First, the subjects performed the theme-identification task during functional magnetic resonance imaging. In this task, pictures depicting social situations were presented with three words, and the subjects were asked to select the best theme word for each picture. The subjects then performed an old-new recognition task in which they were asked to discriminate whether the presented words were old or new. Task performance and neural responses in the old-new recognition task were compared between the subject groups. An independent component analysis of the functional connectivity was performed. The patients with schizophrenia exhibited decreased discriminability and increased activation of the right superior temporal gyrus compared with the controls during correct responses. Furthermore, aberrant network activities were found in the frontopolar and language comprehension networks in the patients. The functional connectivity analysis showed aberrant connectivity in the frontopolar and language comprehension networks in the patients with schizophrenia, and these aberrations possibly contribute to their low recognition performance and social dysfunction. These results suggest that the frontopolar and language comprehension networks are potential therapeutic targets in patients with schizophrenia.

  3. Radiation-induced cellular reproductive death and chromosome aberrations

    International Nuclear Information System (INIS)

    Bedford, J.S.; Mitchell, J.B.; Griggs, H.G.; Bender, M.A.

    1978-01-01

    If a major mode of cell killing by ionizing radiation is the death of cells containing visible chromosomal aberrations, as for example from anaphase-bridge formation at mitosis, then cells bearing such aberrations should be selectively eliminated from the population, resulting in an increased survival potential for the population remaining at each succeeding cell generation. Using synchronized V79B Chinese hamster cells, we measured the aberration frequency and the colony-forming ability of mitotic cells at each of the first three generations following irradiation in G1. Cells were resynchronized by mechanial harvest at each succeeding mitosis after irradiation in order to avoid mixing of generations in the cell population at later sampling times. As anticipated, the chromosome aberration frequencies decreased markedly from the first to the second and from the second to the third mitosis. The surviving fraction, however, was virtually the same for plating assays carried out immediately after irradiation, at the first, or at the second mitosis. The surviving fraction was significantly higher for cells reaching the third postirradiation mitosis. Survival and aberration frequencies were assayed again at approximately the fourteenth postirradiation division, by which time the irradiated and control populations were not significantly different

  4. Primary chromatic aberration elimination via optimization work with genetic algorithm

    Science.gov (United States)

    Wu, Bo-Wen; Liu, Tung-Kuan; Fang, Yi-Chin; Chou, Jyh-Horng; Tsai, Hsien-Lin; Chang, En-Hao

    2008-09-01

    Chromatic Aberration plays a part in modern optical systems, especially in digitalized and smart optical systems. Much effort has been devoted to eliminating specific chromatic aberration in order to match the demand for advanced digitalized optical products. Basically, the elimination of axial chromatic and lateral color aberration of an optical lens and system depends on the selection of optical glass. According to reports from glass companies all over the world, the number of various newly developed optical glasses in the market exceeds three hundred. However, due to the complexity of a practical optical system, optical designers have so far had difficulty in finding the right solution to eliminate small axial and lateral chromatic aberration except by the Damped Least Squares (DLS) method, which is limited in so far as the DLS method has not yet managed to find a better optical system configuration. In the present research, genetic algorithms are used to replace traditional DLS so as to eliminate axial and lateral chromatic, by combining the theories of geometric optics in Tessar type lenses and a technique involving Binary/Real Encoding, Multiple Dynamic Crossover and Random Gene Mutation to find a much better configuration for optical glasses. By implementing the algorithms outlined in this paper, satisfactory results can be achieved in eliminating axial and lateral color aberration.

  5. Chromosomal aberrations in subjects exposed to ionizing radiation

    International Nuclear Information System (INIS)

    Jovicic, D.; Milacic, S.; Kovacevic, R.; Tanaskovic, I.

    2006-01-01

    Occupational exposure is particularly delicate because of chronic exposure to low doses of ionizing radiation and its cumulative effect, where it is important to consider the biological response of body to given conditions of exposure. The objective of this study was the observation of the recovery of the DNA damages in subjects working in the radiation area in two different intervals.Group I, consisting of 30 subjects, was exposed to ionizing radiation and unstable chromosomal aberrations were identified. Group II included the same, re-examined subjects (30) 9 months later. It was verified that 5 (16.67%) subjects still had unstable chromosomal aberrations, although they had been excluded from radiation area Controls groups (C) consisted of 64 subjects that were not exposed to mutagenic agents.The comparison of the control group with the two studied groups revealed the reduction of the unstable aberrations (p<0.05). The total effective doses, which increased with the years spent in radiation area, reflected the yield of chromosomal aberrations. The presence of chromosomal aberrations in some subjects, after the exclusion from the ionising radiation exposure, suggests that the time needed for the recovery of the DNA damages is different, which indicates the individual differences in radiosensitivity as well as different of the reparatory cellular response. (author)

  6. Spherical aberration and other higher-order aberrations in the human eye : from summary wave-front analysis data to optical variables relevant to visual perception

    NARCIS (Netherlands)

    Jansonius, Nomdo M.

    Wave-front analysis data from the human eye are commonly presented using the aberration coefficient c(4)(0) (primary spherical aberration) together with an overall measure of all higher-order aberrations. If groups of subjects are compared, however, the relevance of an observed difference cannot

  7. Height drift correction in non-raster atomic force microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Meyer, Travis R. [Department of Mathematics, University of California Los Angeles, Los Angeles, CA 90095 (United States); Ziegler, Dominik [Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Brune, Christoph [Institute for Computational and Applied Mathematics, University of Münster (Germany); Chen, Alex [Statistical and Applied Mathematical Sciences Institute, Research Triangle Park, NC 27709 (United States); Farnham, Rodrigo; Huynh, Nen; Chang, Jen-Mei [Department of Mathematics and Statistics, California State University Long Beach, Long Beach, CA 90840 (United States); Bertozzi, Andrea L., E-mail: bertozzi@math.ucla.edu [Department of Mathematics, University of California Los Angeles, Los Angeles, CA 90095 (United States); Ashby, Paul D., E-mail: pdashby@lbl.gov [Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States)

    2014-02-01

    We propose a novel method to detect and correct drift in non-raster scanning probe microscopy. In conventional raster scanning drift is usually corrected by subtracting a fitted polynomial from each scan line, but sample tilt or large topographic features can result in severe artifacts. Our method uses self-intersecting scan paths to distinguish drift from topographic features. Observing the height differences when passing the same position at different times enables the reconstruction of a continuous function of drift. We show that a small number of self-intersections is adequate for automatic and reliable drift correction. Additionally, we introduce a fitness function which provides a quantitative measure of drift correctability for any arbitrary scan shape. - Highlights: • We propose a novel height drift correction method for non-raster SPM. • Self-intersecting scans enable the distinction of drift from topographic features. • Unlike conventional techniques our method is unsupervised and tilt-invariant. • We introduce a fitness measure to quantify correctability for general scan paths.

  8. Over-all accuracy of sup(99m)Tc-pertechnetate brain scanning for brain tumours

    International Nuclear Information System (INIS)

    Bjoernsson, O.G.; Petursson, E.; Sigurbjoernsson, B.; Davidsson, D.

    1978-01-01

    A 3-year follow-up and re-evaluation of all scans on all patients referred for brain scanning in Iceland during 1 year was performed in order to assess the diagnostic reliability of radioisotope scanning for brain tumours. The study included 471 patients. Of these 25 had primary brain tumours and 7 brain metastases. Scans were positive and correctly interpreted in 68% of the patients with primary brain tumours and in 3 of the 7 patients with metastases. The over-all accuracy of brain scanning for brain tumours defined as the total number of correct positive scans and correct negative scans versus total number of scans examined was 96%, this figure being mainly influenced by the high number of true negative scans. (orig.) [de

  9. Model PET Scan Activity

    Science.gov (United States)

    Strunk, Amber; Gazdovich, Jennifer; Redouté, Oriane; Reverte, Juan Manuel; Shelley, Samantha; Todorova, Vesela

    2018-05-01

    This paper provides a brief introduction to antimatter and how it, along with other modern physics topics, is utilized in positron emission tomography (PET) scans. It further describes a hands-on activity for students to help them gain an understanding of how PET scans assist in detecting cancer. Modern physics topics provide an exciting way to introduce students to current applications of physics.

  10. Scanning laser Doppler vibrometry

    DEFF Research Database (Denmark)

    Brøns, Marie; Thomsen, Jon Juel

    With a Scanning Laser Doppler Vibrometer (SLDV) a vibrating surface is automatically scanned over predefined grid points, and data processed for displaying vibration properties like mode shapes, natural frequencies, damping ratios, and operational deflection shapes. Our SLDV – a PSV-500H from...

  11. Thyroid Scan and Uptake

    Medline Plus

    Full Text Available Toggle navigation Test/Treatment Patient Type Screening/Wellness Disease/Condition Safety En Español More Info Images/Videos About Us News Physician Resources Professions Site Index A-Z Thyroid Scan and Uptake Thyroid scan and uptake uses ...

  12. Aberrations in preliminary design of ITER divertor impurity influx monitor

    Energy Technology Data Exchange (ETDEWEB)

    Kitazawa, Sin-iti, E-mail: kitazawa.siniti@jaea.go.jp [Naka Fusion Institute, Japan Atomic Energy Agency, JAEA, Naka 311-0193 (Japan); Ogawa, Hiroaki [Naka Fusion Institute, Japan Atomic Energy Agency, JAEA, Naka 311-0193 (Japan); Katsunuma, Atsushi; Kitazawa, Daisuke [Core Technology Center, Nikon Corporation, Yokohama 244-8533 (Japan); Ohmori, Keisuke [Customized Products Business Unit, Nikon Corporation, Mito 310-0843 (Japan)

    2015-12-15

    Highlights: • Divertor impurity influx monitor for ITER (DIM) is procured by JADA. • DIM is designed to observe light from nuclear fusion plasma directly. • DIM is under preliminary design phase. • The spot diagrams were suppressed within the core of receiving fiber. • The aberration of DIM is suppressed in the preliminary design. - Abstract: Divertor impurity influx monitor for ITER (DIM) is a diagnostic system that observes light from nuclear fusion plasma directly. This system is affected by various aberrations because it observes light from the fan-array chord near the divertor in the ultraviolet–near infrared wavelength range. The aberrations should be suppressed to the extent possible to observe the light with very high spatial resolution. In the preliminary design of DIM, spot diagrams were suppressed within the core of the receiving fiber's cross section, and the resulting spatial resolutions satisfied the design requirements.

  13. Estimation and Compensation of aberrations in Spatial Light Modulators

    International Nuclear Information System (INIS)

    Arias, Augusto; Castaneda, Roman

    2011-01-01

    The spatial light modulator (SLM) Holoeye LC-R720 is based on LCoS (Liquid Crystal on Silicon) technology. Due to the induced curvatures on the silicon plate by the production process, there are static aberrations in the wave-fronts modified by the SLM. In order to calculate the aberrated wave-front we used phase-shifting interferometry, an optimization algorithm for far field propagation, and the geometric characterization of the focal spot along the caustic. Zernike polynomials were used for expanding and comparing the wave-fronts. The aberration compensation was carried out by displaying the conjugated transmittance on the SLM. The complexity of the experimental setup and the requirements of the digital processing of each estimation method were comparatively analyzed.

  14. Screening for aberrant behavior in the nuclear industry

    International Nuclear Information System (INIS)

    Borofsky, G.L.

    1987-01-01

    This paper attempts to promote a fuller understanding of how psychological assessment procedures can be used to reduce the threat from aberrant behavior in the nuclear industry. It begins with a discussion of the scientifically based methods that are used by psychologists in constructing, scoring, and interpreting these procedures. This discussion includes an emphasis on the concepts of validity and reliability and their central importance when one is choosing specific psychological screening tools. Criteria for selecting and using psychological assessment procedures when screening for aberrant behavior are also provided. Some commonly used assessment procedures that satisfy these criteria are discussed. A number a psychological assessment procedures specifically recommended for use in screening for aberrant behavior in the nuclear industry are described

  15. Split-plot fractional designs: Is minimum aberration enough?

    DEFF Research Database (Denmark)

    Kulahci, Murat; Ramirez, Jose; Tobias, Randy

    2006-01-01

    Split-plot experiments are commonly used in industry for product and process improvement. Recent articles on designing split-plot experiments concentrate on minimum aberration as the design criterion. Minimum aberration has been criticized as a design criterion for completely randomized fractional...... factorial design and alternative criteria, such as the maximum number of clear two-factor interactions, are suggested (Wu and Hamada (2000)). The need for alternatives to minimum aberration is even more acute for split-plot designs. In a standard split-plot design, there are several types of two...... for completely randomized designs. Consequently, we provide a modified version of the maximum number of clear two-factor interactions design criterion to be used for split-plot designs....

  16. [Frequency of chromosome aberrations in residents of the Semipalatinsk Oblast].

    Science.gov (United States)

    Gubitskaia, E G; Akhmatullina, N B; Vsevolodov, E B; Bishnevskaia, S S; Sharipov, I K; Cherednichenko, O G

    1999-06-01

    Cytogenetic analysis of the population of the Beskaragai district of the Semipalatinsk oblast adjacent to the territory of the nuclear test site was conducted by means of an ecological genetic questionnaire and cytogenetic examination of metaphase chromosomes. An increase in the total mutation level in the region was observed. The frequency of chromosome aberrations among the population of the Beskaragai district (3.2%) was statistically significantly (about 1.5 times) higher than the background levels in the clear regions (from 1 to 2%). Furthermore, the frequency of aberrations in adolescents was comparable with that in the adults. The spectrum of chromosome aberrations pointed to a significant contribution of radiation component to the mutagenesis.

  17. Low chromatic aberration hexapole for molecular state selection

    International Nuclear Information System (INIS)

    Ke, Yi; Deng, Xiao-Bing; Hu, Zhong-Kun

    2016-01-01

    In molecular beam state-selection experiments, the electrostatic hexapole acts as an optical lens, imaging molecules from the source to the focus. The molecular longitudinal velocity spread induces the phenomenon of chromatic aberration, which will reduce the state-selection purity. We propose a scheme which can effectively reduce the chromatic aberration by changing the hexapole voltage operating manner. The hexapole is already charged before molecules arrive at the entrance of the hexapole. When molecules are completely inside the hexapole, the voltage is switched off rapidly at an appropriate time. In this manner, faster molecules travel a longer hexapole focusing region than slower molecules. Therefore the focusing positions of molecules with different velocities become close. Numerical trajectory simulations of molecular state selection are carried out, and the results show that this low chromatic aberration hexapole can significantly improve the state purity from 46.2% to 87.0%. (paper)

  18. Biological dosimetry: chromosomal aberration analysis for dose assessment

    International Nuclear Information System (INIS)

    1986-01-01

    In view of the growing importance of chromosomal aberration analysis as a biological dosimeter, the present report provides a concise summary of the scientific background of the subject and a comprehensive source of information at the technical level. After a review of the basic principles of radiation dosimetry and radiation biology basic information on the biology of lymphocytes, the structure of chromosomes and the classification of chromosomal aberrations are presented. This is followed by a presentation of techniques for collecting blood, storing, transporting, culturing, making chromosomal preparations and scaring of aberrations. The physical and statistical parameters involved in dose assessment are discussed and examples of actual dose assessments taken from the scientific literature are given

  19. Circumflex coronary artery with aberrant origin and atherosclerosis

    International Nuclear Information System (INIS)

    Ozcan, E.; Bozlar, U.; Celik, T.; Tasar, M.

    2012-01-01

    Full text: Introduction: Circumflex (Cx) coronary artery congenital anomaly is reported to be less than 1% incidence. Coronary arteries with aberrant origin are more likely to have atherosclerosis according to some published literatures. Objectives and tasks: In this study we aim to present computed tomography (CT) angiography findings of a patient, who has Cx artery with aberrant origin and atherosclerotic. Materials and methods: 57-year-old woman without any symptoms who has risk factors to atherosclerosis was referred to our clinic for coronary CT angiography. Results: In CT angiography; we detected Cx coronary artery with aberrant origin (right sinus of valsalva) and retroaortic course. Also we saw intimal irregularities and calcified plaque causing severe narrowing in the proximal segment of artery. Right coronary and left anterior descendant arteries had mild atherosclerosis. Conclusion: Coroner CT angiography, which allows multiplanar imaging with high resolution, is an effective diagnostic tool for coronary artery disease, like not only congenital anomalies but also acquired atherosclerotic disease

  20. Aberrations in preliminary design of ITER divertor impurity influx monitor

    International Nuclear Information System (INIS)

    Kitazawa, Sin-iti; Ogawa, Hiroaki; Katsunuma, Atsushi; Kitazawa, Daisuke; Ohmori, Keisuke

    2015-01-01

    Highlights: • Divertor impurity influx monitor for ITER (DIM) is procured by JADA. • DIM is designed to observe light from nuclear fusion plasma directly. • DIM is under preliminary design phase. • The spot diagrams were suppressed within the core of receiving fiber. • The aberration of DIM is suppressed in the preliminary design. - Abstract: Divertor impurity influx monitor for ITER (DIM) is a diagnostic system that observes light from nuclear fusion plasma directly. This system is affected by various aberrations because it observes light from the fan-array chord near the divertor in the ultraviolet–near infrared wavelength range. The aberrations should be suppressed to the extent possible to observe the light with very high spatial resolution. In the preliminary design of DIM, spot diagrams were suppressed within the core of the receiving fiber's cross section, and the resulting spatial resolutions satisfied the design requirements.

  1. X-ray-induced chromosome aberrations in the leucocytes of mouse and man

    International Nuclear Information System (INIS)

    Preston, R.J.; Brewen, J.G.

    1978-01-01

    In earlier studies it was shown that the frequency of dicentrics induced by X-rays in human leucocytes was about twice that induced in mouse leucocytes. The frequencies of deletions were similar in both species. However, the mouse cultures were fixed at 60 h and the human cultures at 54 h. In both cases it was likely that some of the cells analysed were in their second post-treatment mitosis. Further studies were carried out using fixation times of 48 h for both mouse and human cultures (three different human donors were used). The same relationships held here, namely twice as many dicentrics in humans, and similar deletion frequencies in both. The aberration frequencies observed were corrected to take account of second-diversion cells by assuming that cells containing a dicentric without an accompanying fragment were in their second division. There were more such cells in mouse than in human cultures. Further to increase reliance on the conclusions, cultures were fixed at the earliest times that 300 cells per dose could be obtained - 36 h for the mouse, 42 h for the human. The frequencies of dicentrics were increased in both, and a relationship of about 2:1 for human to mouse was obtained. Deletion frequencies were similar in both. Since no dicentrics without fragments were obtained, it appeared that aberration frequencies in first-division cells only were being compared. (author)

  2. Compensation for longitudinal chromatic aberration in the eye of the firefly squid, Watasenia scintillans.

    Science.gov (United States)

    Kröger, Ronald H H; Gislén, Anna

    2004-01-01

    The camera eyes of fishes and cephalopods have come forth by convergent evolution. In a variety of vertebrates capable of color vision, longitudinal chromatic aberration (LCA) of the optical system is corrected for by the exactly tuned longitudinal spherical aberration (LSA) of the crystalline lens. The LSA leads to multiple focal lengths, such that several wavelengths can be focused on the retina. We investigated whether that is also the case in the firefly squid (Watasenia scintillans), a cephalopod species that is likely to have color vision. It was found that the lens of W. scintillans is virtually free of LSA and uncorrected for LCA. However, the eye does not suffer from LCA because of a banked retina. Photoreceptors sensitive to short and long wavelengths are located at appropriate distances from the lens, such that they receive well-focused images. Such a design is an excellent solution for the firefly squid because a large area of the retina is monochromatically organized and it allows for double use of the surface area in the dichromatically organized part of the retina. However, it is not a universal solution since compensation for LCA by a banked retina requires that eye size and/or spectral separation between photopigments is small.

  3. Transverse section scanning mechanism

    International Nuclear Information System (INIS)

    Doherty, E.J.

    1978-01-01

    Apparatus is described for scanning a transverse, radionuclide scan-field using an array of focussed collimators. The collimators are movable tangentially on rails, driven by a single motor via a coupled screw. The collimators are also movable in a radial direction on rails driven by a step motor via coupled screws and bevel gears. Adjacent bevel gears rotate in opposite directions so adjacent collimators move in radially opposite directions. In use, the focal point of each collimator scans at least half of the scan-field, e.g. a human head located in the central aperture, and the electrical outputs of detectors associated with each collimator are used to determine the distribution of radioactive emission intensity at a number of points in the scan-field. (author)

  4. LIDAR COMBINED SCANNING UNIT

    Directory of Open Access Journals (Sweden)

    V. V. Elizarov

    2016-11-01

    Full Text Available Subject of Research. The results of lidar combined scanning unit development for locating leaks of hydrocarbons are presented The unit enables to perform high-speed scanning of the investigated space in wide and narrow angle fields. Method. Scanning in a wide angular field is produced by one-line scanning path by means of the movable aluminum mirror with a frequency of 20Hz and amplitude of 20 degrees of swing. Narrowband scanning is performed along a spiral path by the deflector. The deflection of the beam is done by rotation of the optical wedges forming part of the deflector at an angle of ±50. The control function of the scanning node is performed by a specialized software product written in C# programming language. Main Results. This scanning unit allows scanning the investigated area at a distance of 50-100 m with spatial resolution at the level of 3 cm. The positioning accuracy of the laser beam in space is 15'. The developed scanning unit gives the possibility to browse the entire investigated area for the time not more than 1 ms at a rotation frequency of each wedge from 50 to 200 Hz. The problem of unambiguous definition of the beam geographical coordinates in space is solved at the software level according to the rotation angles of the mirrors and optical wedges. Lidar system coordinates are determined by means of GPS. Practical Relevance. Development results open the possibility for increasing the spatial resolution of scanning systems of a wide range of lidars and can provide high positioning accuracy of the laser beam in space.

  5. In vivo chromatic aberration in eyes implanted with intraocular lenses.

    Science.gov (United States)

    Pérez-Merino, Pablo; Dorronsoro, Carlos; Llorente, Lourdes; Durán, Sonia; Jiménez-Alfaro, Ignacio; Marcos, Susana

    2013-04-12

    To measure in vivo and objectively the monochromatic aberrations at different wavelengths, and the chromatic difference of focus between green and infrared wavelengths in eyes implanted with two models of intraocular lenses (IOL). EIGHTEEN EYES PARTICIPATED IN THIS STUDY: nine implanted with Tecnis ZB99 1-Piece acrylic IOL and nine implanted with AcrySof SN60WF IOL. A custom-developed laser ray tracing (LRT) aberrometer was used to measure the optical aberrations, at 532 nm and 785 nm wavelengths. The monochromatic wave aberrations were described using a fifth-order Zernike polynomial expansion. The chromatic difference of focus was estimated as the difference between the equivalent spherical errors corresponding to each wavelength. Wave aberration measurements were highly reproducible. Except for the defocus term, no significant differences in high order aberrations (HOA) were found between wavelengths. The average chromatic difference of focus was 0.46 ± 0.15 diopters (D) in the Tecnis group, and 0.75 ± 0.12 D in the AcrySof group, and the difference was statistically significant (P Chromatic difference of focus in the AcrySof group was not statistically significantly different from the Longitudinal chromatic aberration (LCA) previously reported in a phakic population (0.78 ± 0.16 D). The impact of LCA on retinal image quality (measured in terms of Strehl ratio) was drastically reduced when considering HOA and astigmatism in comparison with a diffraction-limited eye, yielding the differences in retinal image quality between Tecnis and AcrySof IOLs not significant. LRT aberrometry at different wavelengths is a reproducible technique to evaluate the chromatic difference of focus objectively in eyes implanted with IOLs. Replacement of the crystalline lens by the IOL did not increase chromatic difference of focus above that of phakic eyes in any of the groups. The AcrySof group showed chromatic difference of focus values very similar to physiological values in

  6. In vivo longitudinal chromatic aberration of pseudophakic eyes.

    Science.gov (United States)

    Siedlecki, Damian; Jóźwik, Agnieszka; Zając, Marek; Hill-Bator, Aneta; Turno-Kręcicka, Anna

    2014-02-01

    To present the results of longitudinal chromatic aberration measurements on two groups of pseudophakic eyes in comparison to healthy eyes. The longitudinal chromatic aberration of the eye, defined as chromatic difference of refraction with disabled accommodation, was measured with the use of a visual refractometer with a custom-designed target illuminator consisting of a narrow-band RGB diode (blue λb = 470 ± 15 nm; green λg = 525 ± 18 nm; red λr = 660 ± 10 nm). The measurements were performed on nine eyes implanted with AcrySof IQ SN60WF, 14 eyes implanted with AcrySof SA60AT, and 10 phakic eyes under cycloplegia. The mean values of the longitudinal chromatic aberration between 470 and 660 nm for the control group was 1.12 ± 0.14 D. For SA60AT group, it was 1.45 ± 0.42 D whereas for SN60WF it was 1.17 ± 0.52 D. The statistical test showed significant difference between SA60AT and the control group (p chromatic aberration in vivo can be easily and reliably estimated with an adapted visual refractometer. The two groups of pseudophakic eyes measured in this study showed different values of chromatic aberration. Its magnitude for SA60AT group was significantly larger than for the control group whereas for SN60WF the difference was not significant. The optical material used for intraocular lens design may have significant influence on the magnitude of the chromatic aberration of the pseudophakic eye, and therefore on its optical and visual performance in polychromatic light.

  7. Absence of orthotopic renal vein with aberrant suprarenal venous drainage; A case report

    International Nuclear Information System (INIS)

    Kim, Eu gene; Jeon, Yong Sun; Cho, Soon Gu; Hong, Kee Chun; Park, Keun Myung; Lee, Tack

    2015-01-01

    A CT scan of a 49-year-old female incidentally revealed a tortuous vascular structure in the right suprarenal space. According to angiographic evaluation of the right renal vessels, the right renal artery was single with normal diameter, and there was no venous drainage through the main right renal vein (orthotopic renal vein). The venous drainage of the right kidney flowed through the tortuous suprarenal vascular structure into the inferior vena cava. The color Doppler ultrasound revealed the monophasic waveform in that vascular structure without flow disturbance. The renal function and the result of urinalysis of the patient were normal, and any other congenital malformation was not found. Absence of the orthotopic renal vein and aberrant suprarenal venous drainage is a very rare congenital anomaly, and it should be discriminated from the other pathologic conditions

  8. Absence of orthotopic renal vein with aberrant suprarenal venous drainage; A case report

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Eu gene; Jeon, Yong Sun; Cho, Soon Gu; Hong, Kee Chun; Park, Keun Myung; Lee, Tack [Inha University Hospital, Incheon (Korea, Republic of)

    2015-06-15

    A CT scan of a 49-year-old female incidentally revealed a tortuous vascular structure in the right suprarenal space. According to angiographic evaluation of the right renal vessels, the right renal artery was single with normal diameter, and there was no venous drainage through the main right renal vein (orthotopic renal vein). The venous drainage of the right kidney flowed through the tortuous suprarenal vascular structure into the inferior vena cava. The color Doppler ultrasound revealed the monophasic waveform in that vascular structure without flow disturbance. The renal function and the result of urinalysis of the patient were normal, and any other congenital malformation was not found. Absence of the orthotopic renal vein and aberrant suprarenal venous drainage is a very rare congenital anomaly, and it should be discriminated from the other pathologic conditions.

  9. Scaling laws for aberrations in magnetic quadrupole lens systems

    International Nuclear Information System (INIS)

    Moses, R.W.; Heighway, E.A.; Christian, R.S.; Dragt, A.J.

    1987-01-01

    A comparison has been made of the third-order (spherical) abberrations in magnetic quadrupole lenses for use in conventional charged particle beam transport systems. An analytical description of the abberrations is presented and this is compared with the results of high order numerical integration. The dependence of the aberration strength on the system geometry and f number is given and a comparison of doublet and triplet systems made. The reduction of the aberrations in both doublet and triplet systems using embedded magnetic octupole lenses is also discussed and analytical predictions are given

  10. Selective corneal optical aberration (SCOA) for customized ablation

    Science.gov (United States)

    Jean, Benedikt J.; Bende, Thomas

    2001-06-01

    Wavefront analysis still have some technical problems which may be solved within the next years. There are some limitations to use wavefront as a diagnostic tool for customized ablation alone. An ideal combination would be wavefront and topography. Meanwhile Selective Corneal Aberration is a method to visualize the optical quality of a measured corneal surface. It is based on a true measured 3D elevation information of a video topometer. Thus values can be interpreted either using Zernike polynomials or visualized as a so called color coded surface quality map. This map gives a quality factor (corneal aberration) for each measured point of the cornea.

  11. Propagation of highly aberrated laser beams in nonquadratic plasma waveguides

    International Nuclear Information System (INIS)

    Feit, M.D.; Fleck, J.A. Jr.; Morris, J.R.

    1977-01-01

    The propagation of a laser beam in a plasma column several meters long with a realistic electron density distribution is examined. The electron density distribution is based on laser-beam heating at z=0, but is otherwise uncoupled to the laser beam. The aberrated nature of the resulting lenslike medium leads to essentially aperiodic beam properties, which contrast with the completely periodic properties of Gaussian beams propagating in quadratic lenslike media. The beam is nonetheless stably trapped. These aberrated-beam properties also help to stabilize the beam against axial variations in refractive index

  12. Elimination of aberrations in wide-aperture magnetoelectrostatic plasma lenses

    International Nuclear Information System (INIS)

    Butenko, V.I.; Ivanov, B.I.

    2003-01-01

    A computer model is devised for a Morozov plasma lens, in which the magnetic surfaces are equipotential surfaces of the electric field. Results are presented from numerical modeling of the focusing of ions with allowance for their longitudinal, radial, and azimuthal motions. The strengths and spatial distributions of the magnetic and electric fields are optimized. The methods for removing moment, geometric, and chromatic aberrations are analyzed. The effect of a discrete distribution of the potentials on ion focusing is modeled, and the related aberrations are examined. A computer model of an achromatic two-lens system is considered

  13. Papillary carcinoma in median aberrant thyroid (ectopic) - case report.

    Science.gov (United States)

    Hebbar K, Ashwin; K, Shashidhar; Deshmane, Vijaya Laxmi; Kumar, Veerendra; Arjunan, Ravi

    2014-06-01

    Median ectopic thyroid may be encountered anywhere from the foramen caecum to the diaphragm. Non lingual median aberrant thyroid (incomplete descent) usually found in the infrahyoid region and malignant transformation in this ectopic thyroid tissue is very rare. We report an extremely rare case of papillary carcinoma in non lingual median aberrant thyroid in a 25-year-old female. The differentiation between a carcinoma arising in the median ectopic thyroid tissue and a metastatic papillary carcinoma from an occult primary in the main thyroid gland is also discussed.

  14. Detector correction in large container inspection systems

    CERN Document Server

    Kang Ke Jun; Chen Zhi Qiang

    2002-01-01

    In large container inspection systems, the image is constructed by parallel scanning with a one-dimensional detector array with a linac used as the X-ray source. The linear nonuniformity and nonlinearity of multiple detectors and the nonuniform intensity distribution of the X-ray sector beam result in horizontal striations in the scan image. This greatly impairs the image quality, so the image needs to be corrected. The correction parameters are determined experimentally by scaling the detector responses at multiple points with logarithm interpolation of the results. The horizontal striations are eliminated by modifying the original image data with the correction parameters. This method has proven to be effective and applicable in large container inspection systems

  15. Role of bone scanning in osteomalacia

    International Nuclear Information System (INIS)

    Fogelman, I.; McKillop, J.H.; Bessent, R.G.; Boyle, I.T.; Turner, J.G.; Greig, W.R.

    1978-01-01

    The presence of eight ''metabolic features'' was assessed on the bone scintigrams of ten patients with osteomalacia. In all of these bone images, sufficient features were present to strongly suggest a metabolic disorder. These scintiphotos were included in a controlled blind study using 30 normal bone scans and 20 scans of metastatic disease. Nine of the ten metabolic bone images were correctly identified by two independent observers. Skeletal uptake of radiotracer, expressed as bone-to-soft-tissue ratio, was significantly higher in the osteomalacic patients than in a group of 80 controls

  16. Topography and Higher Order Corneal Aberrations of the Fellow Eye in Unilateral Keratoconus.

    Science.gov (United States)

    Aksoy, Sibel; Akkaya, Sezen; Özkurt, Yelda; Kurna, Sevda; Açıkalın, Banu; Şengör, Tomris

    2017-10-01

    Comparison of topography and corneal higher order aberrations (HOA) data of fellow normal eyes of unilateral keratoconus patients with keratoconus eyes and control group. The records of 196 patients with keratoconus were reviewed. Twenty patients were identified as unilateral keratoconus. The best corrected visual acuity (BCVA), topography and aberration data of the unilateral keratoconus patients' normal eyes were compared with their contralateral keratoconus eyes and with control group eyes. For statistical analysis, flat and steep keratometry values, average corneal power, cylindrical power, surface regularity index (SRI), surface asymmetry index (SAI), inferior-superior ratio (I-S), keratoconus prediction index, and elevation-depression power (EDP) and diameter (EDD) topography indices were selected. Mean age of the unilateral keratoconus patients was 26.05±4.73 years and that of the control group was 23.6±8.53 years (p>0.05). There was no statistical difference in BCVA between normal and control eyes (p=0.108), whereas BCVA values were significantly lower in eyes with keratoconus (p=0.001). Comparison of quantitative topographic indices between the groups showed that all indices except the I-S ratio were significantly higher in the normal group than in the control group (p<0.05). The most obvious differences were in the SRI, SAI, EDP, and EDD values. All topographic indices were higher in the keratoconus eyes compared to the normal fellow eyes. There was no difference between normal eyes and the control group in terms of spherical aberration, while coma, trefoil, irregular astigmatism, and total HOA values were higher in the normal eyes of unilateral keratoconus patients (p<0.05). All HOA values were higher in keratoconus eyes than in the control group. According to our study, SRI, SAI, EDP, EDD values, and HOA other than spherical aberration were higher in the clinically and topographically normal fellow eyes of unilateral keratoconus patients when compared

  17. Chromosomal Aberrations in DNA Repair Defective Cell Lines: Comparisons of Dose Rate and Radiation Quality

    Science.gov (United States)

    George, K. A.; Hada, M.; Patel, Z.; Huff, J.; Pluth, J. M.; Cucinotta, F. A.

    2009-01-01

    Chromosome aberration yields were assessed in DNA double-strand break repair (DSB) deficient cells after acute doses of gamma-rays or high-LET iron nuclei, or low dose-rate (0.018 Gy/hr) gamma-rays. We studied several cell lines including fibroblasts deficient in ATM (product of the gene that is mutated in ataxia telangiectasia patients) or NBS (product of the gene mutated in the Nijmegen breakage syndrome), and gliomablastoma cells that are proficient or lacking in DNA-dependent protein kinase, DNA-PK activity. Chromosomes were analyzed using the fluorescence in-situ hybridization (FISH) chromosome painting method in cells at the first division post-irradiation and chromosome aberrations were identified as either simple exchanges (translocations and dicentrics) or complex exchanges (involving >2 breaks in 2 or more chromosomes). Gamma radiation induced higher yields of both simple and complex exchanges in the DSB repair defective cells than in the normal cells. The quadratic dose-response terms for both chromosome exchange types were significantly higher for the ATM and NBS defective lines than for normal fibroblasts. However, the linear dose-response term was significantly higher only for simple exchanges in the NBS cells. Large increases in the quadratic dose response terms indicate the important roles of ATM and NBS in chromatin modifications that facilitate correct DSB repair and minimize aberration formation. Differences in the response of AT and NBS deficient cells at lower doses suggests important questions about the applicability of observations of radiation sensitivity at high dose to low dose exposures. For all iron nuclei irradiated cells, regression models preferred purely linear and quadratic dose responses for simple and complex exchanges, respectively. All the DNA repair defective cell lines had lower Relative biological effectiveness (RBE) values than normal cells, the lowest being for the DNA-PK-deficient cells, which was near unity. To further

  18. Laser Scanning in Forests

    Directory of Open Access Journals (Sweden)

    Håkan Olsson

    2012-09-01

    Full Text Available The introduction of Airborne Laser Scanning (ALS to forests has been revolutionary during the last decade. This development was facilitated by combining earlier ranging lidar discoveries [1–5], with experience obtained from full-waveform ranging radar [6,7] to new airborne laser scanning systems which had components such as a GNSS receiver (Global Navigation Satellite System, IMU (Inertial Measurement Unit and a scanning mechanism. Since the first commercial ALS in 1994, new ALS-based forest inventory approaches have been reported feasible for operational activities [8–12]. ALS is currently operationally applied for stand level forest inventories, for example, in Nordic countries. In Finland alone, the adoption of ALS for forest data collection has led to an annual savings of around 20 M€/year, and the work is mainly done by companies instead of governmental organizations. In spite of the long implementation times and there being a limited tradition of making changes in the forest sector, laser scanning was commercially and operationally applied after about only one decade of research. When analyzing high-ranked journal papers from ISI Web of Science, the topic of laser scanning of forests has been the driving force for the whole laser scanning research society over the last decade. Thus, the topic “laser scanning in forests” has provided a significant industrial, societal and scientific impact. [...

  19. Bone scan in pediatrics

    International Nuclear Information System (INIS)

    Gordon, I.; Peters, A.M.

    1987-01-01

    In 1984, a survey carried out in 21 countries in Europe showed that bone scintigraphy comprised 16% of all paediatric radioisotope scans. Although the value of bone scans in paediatrics is potentially great, their quality varies greatly, and poor-quality images are giving this valuable technique a bad reputation. The handling of children requires a sensitive staff and the provision of a few simple inexpensive items of distraction. Attempting simply to scan a child between two adult patients in a busy general department is a recipe for an unhappy, uncooperative child with the probable result of poor images. The intravenous injection of isotope should be given adjacent to the gamma camera room, unless dynamic scans are required, so that the child does not associate the camera with the injection. This injection is best carried out by someone competent in paediatric venipunture; the entire procedure should be explained to the child and parent, who should remain with child throughout. It is naive to think that silence makes for a cooperative child. The sensitivity of bone-seeking radioisotope tracers and the marked improvement in gamma camera resolution has allowed the bone scanning to become an integrated technique in the assessment of children suspected of suffering from pathological bone conditions. The tracer most commonly used for routine bone scanning is 99m Tc diphosphonate (MDP); other isotopes used include 99m Tc colloid for bone marrow scans and 67 Ga citrate and 111 In white blood cells ( 111 In WBC) for investigation of inflammatory/infective lesions

  20. NWS Corrections to Observations

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Form B-14 is the National Weather Service form entitled 'Notice of Corrections to Weather Records.' The forms are used to make corrections to observations on forms...

  1. Corrective Jaw Surgery

    Medline Plus

    Full Text Available ... more surgeries depending on the extent of the repair needed. Click here to find out more. Corrective ... more surgeries depending on the extent of the repair needed. Click here to find out more. Corrective ...

  2. Corrective Jaw Surgery

    Medline Plus

    Full Text Available ... Jaw Surgery Download Download the ebook for further information Corrective jaw, or orthognathic surgery is performed by ... your treatment. Correction of Common Dentofacial Deformities ​ ​ The information provided here is not intended as a substitute ...

  3. Genome-wide scan of healthy human connectome discovers SPON1 gene variant influencing dementia severity

    Science.gov (United States)

    Jahanshad, Neda; Rajagopalan, Priya; Hua, Xue; Hibar, Derrek P.; Nir, Talia M.; Toga, Arthur W.; Jack, Clifford R.; Saykin, Andrew J.; Green, Robert C.; Weiner, Michael W.; Medland, Sarah E.; Montgomery, Grant W.; Hansell, Narelle K.; McMahon, Katie L.; de Zubicaray, Greig I.; Martin, Nicholas G.; Wright, Margaret J.; Thompson, Paul M.; Weiner, Michael; Aisen, Paul; Weiner, Michael; Aisen, Paul; Petersen, Ronald; Jack, Clifford R.; Jagust, William; Trojanowski, John Q.; Toga, Arthur W.; Beckett, Laurel; Green, Robert C.; Saykin, Andrew J.; Morris, John; Liu, Enchi; Green, Robert C.; Montine, Tom; Petersen, Ronald; Aisen, Paul; Gamst, Anthony; Thomas, Ronald G.; Donohue, Michael; Walter, Sarah; Gessert, Devon; Sather, Tamie; Beckett, Laurel; Harvey, Danielle; Gamst, Anthony; Donohue, Michael; Kornak, John; Jack, Clifford R.; Dale, Anders; Bernstein, Matthew; Felmlee, Joel; Fox, Nick; Thompson, Paul; Schuff, Norbert; Alexander, Gene; DeCarli, Charles; Jagust, William; Bandy, Dan; Koeppe, Robert A.; Foster, Norm; Reiman, Eric M.; Chen, Kewei; Mathis, Chet; Morris, John; Cairns, Nigel J.; Taylor-Reinwald, Lisa; Trojanowki, J.Q.; Shaw, Les; Lee, Virginia M.Y.; Korecka, Magdalena; Toga, Arthur W.; Crawford, Karen; Neu, Scott; Saykin, Andrew J.; Foroud, Tatiana M.; Potkin, Steven; Shen, Li; Khachaturian, Zaven; Frank, Richard; Snyder, Peter J.; Molchan, Susan; Kaye, Jeffrey; Quinn, Joseph; Lind, Betty; Dolen, Sara; Schneider, Lon S.; Pawluczyk, Sonia; Spann, Bryan M.; Brewer, James; Vanderswag, Helen; Heidebrink, Judith L.; Lord, Joanne L.; Petersen, Ronald; Johnson, Kris; Doody, Rachelle S.; Villanueva-Meyer, Javier; Chowdhury, Munir; Stern, Yaakov; Honig, Lawrence S.; Bell, Karen L.; Morris, John C.; Ances, Beau; Carroll, Maria; Leon, Sue; Mintun, Mark A.; Schneider, Stacy; Marson, Daniel; Griffith, Randall; Clark, David; Grossman, Hillel; Mitsis, Effie; Romirowsky, Aliza; deToledo-Morrell, Leyla; Shah, Raj C.; Duara, Ranjan; Varon, Daniel; Roberts, Peggy; Albert, Marilyn; Onyike, Chiadi; Kielb, Stephanie; Rusinek, Henry; de Leon, Mony J.; Glodzik, Lidia; De Santi, Susan; Doraiswamy, P. Murali; Petrella, Jeffrey R.; Coleman, R. Edward; Arnold, Steven E.; Karlawish, Jason H.; Wolk, David; Smith, Charles D.; Jicha, Greg; Hardy, Peter; Lopez, Oscar L.; Oakley, MaryAnn; Simpson, Donna M.; Porsteinsson, Anton P.; Goldstein, Bonnie S.; Martin, Kim; Makino, Kelly M.; Ismail, M. Saleem; Brand, Connie; Mulnard, Ruth A.; Thai, Gaby; Mc-Adams-Ortiz, Catherine; Womack, Kyle; Mathews, Dana; Quiceno, Mary; Diaz-Arrastia, Ramon; King, Richard; Weiner, Myron; Martin-Cook, Kristen; DeVous, Michael; Levey, Allan I.; Lah, James J.; Cellar, Janet S.; Burns, Jeffrey M.; Anderson, Heather S.; Swerdlow, Russell H.; Apostolova, Liana; Lu, Po H.; Bartzokis, George; Silverman, Daniel H.S.; Graff-Radford, Neill R.; Parfitt, Francine; Johnson, Heather; Farlow, Martin R.; Hake, Ann Marie; Matthews, Brandy R.; Herring, Scott; van Dyck, Christopher H.; Carson, Richard E.; MacAvoy, Martha G.; Chertkow, Howard; Bergman, Howard; Hosein, Chris; Black, Sandra; Stefanovic, Bojana; Caldwell, Curtis; Hsiung, Ging-Yuek Robin; Feldman, Howard; Mudge, Benita; Assaly, Michele; Kertesz, Andrew; Rogers, John; Trost, Dick; Bernick, Charles; Munic, Donna; Kerwin, Diana; Mesulam, Marek-Marsel; Lipowski, Kristina; Wu, Chuang-Kuo; Johnson, Nancy; Sadowsky, Carl; Martinez, Walter; Villena, Teresa; Turner, Raymond Scott; Johnson, Kathleen; Reynolds, Brigid; Sperling, Reisa A.; Johnson, Keith A.; Marshall, Gad; Frey, Meghan; Yesavage, Jerome; Taylor, Joy L.; Lane, Barton; Rosen, Allyson; Tinklenberg, Jared; Sabbagh, Marwan; Belden, Christine; Jacobson, Sandra; Kowall, Neil; Killiany, Ronald; Budson, Andrew E.; Norbash, Alexander; Johnson, Patricia Lynn; Obisesan, Thomas O.; Wolday, Saba; Bwayo, Salome K.; Lerner, Alan; Hudson, Leon; Ogrocki, Paula; Fletcher, Evan; Carmichael, Owen; Olichney, John; DeCarli, Charles; Kittur, Smita; Borrie, Michael; Lee, T.-Y.; Bartha, Rob; Johnson, Sterling; Asthana, Sanjay; Carlsson, Cynthia M.; Potkin, Steven G.; Preda, Adrian; Nguyen, Dana; Tariot, Pierre; Fleisher, Adam; Reeder, Stephanie; Bates, Vernice; Capote, Horacio; Rainka, Michelle; Scharre, Douglas W.; Kataki, Maria; Zimmerman, Earl A.; Celmins, Dzintra; Brown, Alice D.; Pearlson, Godfrey D.; Blank, Karen; Anderson, Karen; Saykin, Andrew J.; Santulli, Robert B.; Schwartz, Eben S.; Sink, Kaycee M.; Williamson, Jeff D.; Garg, Pradeep; Watkins, Franklin; Ott, Brian R.; Querfurth, Henry; Tremont, Geoffrey; Salloway, Stephen; Malloy, Paul; Correia, Stephen; Rosen, Howard J.; Miller, Bruce L.; Mintzer, Jacobo; Longmire, Crystal Flynn; Spicer, Kenneth; Finger, Elizabeth; Rachinsky, Irina; Rogers, John; Kertesz, Andrew; Drost, Dick

    2013-01-01

    Aberrant connectivity is implicated in many neurological and psychiatric disorders, including Alzheimer’s disease and schizophrenia. However, other than a few disease-associated candidate genes, we know little about the degree to which genetics play a role in the brain networks; we know even less about specific genes that influence brain connections. Twin and family-based studies can generate estimates of overall genetic influences on a trait, but genome-wide association scans (GWASs) can screen the genome for specific variants influencing the brain or risk for disease. To identify the heritability of various brain connections, we scanned healthy young adult twins with high-field, high-angular resolution diffusion MRI. We adapted GWASs to screen the brain’s connectivity pattern, allowing us to discover genetic variants that affect the human brain’s wiring. The association of connectivity with the SPON1 variant at rs2618516 on chromosome 11 (11p15.2) reached connectome-wide, genome-wide significance after stringent statistical corrections were enforced, and it was replicated in an independent subsample. rs2618516 was shown to affect brain structure in an elderly population with varying degrees of dementia. Older people who carried the connectivity variant had significantly milder clinical dementia scores and lower risk of Alzheimer’s disease. As a posthoc analysis, we conducted GWASs on several organizational and topological network measures derived from the matrices to discover variants in and around genes associated with autism (MACROD2), development (NEDD4), and mental retardation (UBE2A) significantly associated with connectivity. Connectome-wide, genome-wide screening offers substantial promise to discover genes affecting brain connectivity and risk for brain diseases. PMID:23471985

  4. Significance of MR angiography in the diagnosis of aberrant renal arteries as the cause of ureteropelvic junction obstruction in children; Stellenwert der MR-Angiografie in der Diagnostik aberrierender Nierenarterien als Ursache einer Ureterabgangsstenose bei Kindern

    Energy Technology Data Exchange (ETDEWEB)

    Ritter, L.; Sorge, I.; Hirsch, F.W.; Vieweger, A. [Leipzig Univ. (Germany). Dept. of Pediatric Radiology; Goetz, G.; Lehnert, T.; Buehligen, U.; Geyer, C. [Leipzig Univ. (Germany). Dept. of Pediatric Surgery

    2015-01-15

    To determine the importance of MRI with contrast-enhanced MRA for the detection or exclusion of aberrant or obstructing renal arteries in ureteropelvic junction obstruction in children. Key word-based search in RIS database (ureteropelvic junction obstruction/MRI) and retrospective comparison of arterial findings from preoperative contrast-enhanced MRA and intra-operative inspection. From 2007 to 2013, 19 children with ureteropelvic junction obstruction underwent contrast-enhanced MRA. Based on the results of the MRI scan and MAG3 scintigraphy, the children were referred to surgery (Anderson-Hynes-pyeloplasty). An aberrant renal artery was diagnosed with MRI in 14 of 19 children, and intra-operative inspection confirmed 13 of those 14. In the remaining 5 children, no aberrant vessel could be observed in MRI and this was confirmed intra-operatively in 3 of the 5 cases, while in the remaining 2, an aberrant vessel was found. Of the 14 children with aberrant vessels, 12 underwent surgery due to assumed ureteral obstruction, which was confirmed by surgery in 11 cases. In one case, an aberrant artery was found intra-operatively, but obstruction could not be confirmed. In one of the 14 children, the vessel was found in MRI, but its obstructing character was negated via MRA, which was confirmed intra-operatively. In the diagnosis of aberrant and obstructing renal arteries, contrast-enhanced MRA presents 85 % sensitivity and 80 % specificity, with a positive predictive value of 0.8. MRI with contrast-enhanced MRA is suitable to detect aberrant and obstructing renal arteries. An obstructive effect of the aberrant vessel is to be assumed if the vessel has a close relationship to the ureteropelvic junction and if it is linearly stretched.

  5. Aberration of a negative ion beam caused by space charge effect.

    Science.gov (United States)

    Miyamoto, K; Wada, S; Hatayama, A

    2010-02-01

    Aberrations are inevitable when the charged particle beams are extracted, accelerated, transmitted, and focused with electrostatic and magnetic fields. In this study, we investigate the aberration of a negative ion accelerator for a neutral beam injector theoretically, especially the spherical aberration caused by the negative ion beam expansion due to the space charge effect. The negative ion current density profiles with the spherical aberration are compared with those without the spherical aberration. It is found that the negative ion current density profiles in a log scale are tailed due to the spherical aberration.

  6. Aberration of a negative ion beam caused by space charge effect

    International Nuclear Information System (INIS)

    Miyamoto, K.; Wada, S.; Hatayama, A.

    2010-01-01

    Aberrations are inevitable when the charged particle beams are extracted, accelerated, transmitted, and focused with electrostatic and magnetic fields. In this study, we investigate the aberration of a negative ion accelerator for a neutral beam injector theoretically, especially the spherical aberration caused by the negative ion beam expansion due to the space charge effect. The negative ion current density profiles with the spherical aberration are compared with those without the spherical aberration. It is found that the negative ion current density profiles in a log scale are tailed due to the spherical aberration.

  7. Aberration of a negative ion beam caused by space charge effect

    Energy Technology Data Exchange (ETDEWEB)

    Miyamoto, K. [Naruto University of Education, 748 Nakashima, Takashima, Naruto-cho, Naruto-shi, Tokushima 772-8502 (Japan); Wada, S.; Hatayama, A. [Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522 (Japan)

    2010-02-15

    Aberrations are inevitable when the charged particle beams are extracted, accelerated, transmitted, and focused with electrostatic and magnetic fields. In this study, we investigate the aberration of a negative ion accelerator for a neutral beam injector theoretically, especially the spherical aberration caused by the negative ion beam expansion due to the space charge effect. The negative ion current density profiles with the spherical aberration are compared with those without the spherical aberration. It is found that the negative ion current density profiles in a log scale are tailed due to the spherical aberration.

  8. Differential algebraic method for arbitrary order curvilinear-axis combined geometric-chromatic aberration analysis

    International Nuclear Information System (INIS)

    Cheng Min; Tang Tiantong; Lu Yilong; Yao Zhenhua

    2003-01-01

    The principle of differential algebra is applied to analyse and calculate arbitrary order curvilinear-axis combined geometric-chromatic aberrations of electron optical systems. Expressions of differential algebraic form of high order combined aberrations are obtained and arbitrary order combined aberrations can be calculated numerically. As an example, a typical wide electron beam focusing system with curved optical axes named magnetic immersion lens has been studied. All the second-order and third-order combined geometric-chromatic aberrations of the lens have been calculated, and the patterns of the corresponding geometric aberrations and combined aberrations have been given as well

  9. Increasing the field of view of adaptive optics scanning laser ophthalmoscopy.

    Science.gov (United States)

    Laslandes, Marie; Salas, Matthias; Hitzenberger, Christoph K; Pircher, Michael

    2017-11-01

    An adaptive optics scanning laser ophthalmoscope (AO-SLO) set-up with two deformable mirrors (DM) is presented. It allows high resolution imaging of the retina on a 4°×4° field of view (FoV), considering a 7 mm pupil diameter at the entrance of the eye. Imaging on such a FoV, which is larger compared to classical AO-SLO instruments, is allowed by the use of the two DMs. The first DM is located in a plane that is conjugated to the pupil of the eye and corrects for aberrations that are constant in the FoV. The second DM is conjugated to a plane that is located ∼0.7 mm anterior to the retina. This DM corrects for anisoplanatism effects within the FoV. The control of the DMs is performed by combining the classical AO technique, using a Shack-Hartmann wave-front sensor, and sensorless AO, which uses a criterion characterizing the image quality. The retinas of four healthy volunteers were imaged in-vivo with the developed instrument. In order to assess the performance of the set-up and to demonstrate the benefits of the 2 DM configuration, the acquired images were compared with images taken in conventional conditions, on a smaller FoV and with only one DM. Moreover, an image of a larger patch of the retina was obtained by stitching of 9 images acquired with a 4°×4° FoV, resulting in a total FoV of 10°×10°. Finally, different retinal layers were imaged by shifting the focal plane.

  10. Experimental verification of the minimum number of diffractive zones for effective chromatic correction in the LWIR

    Science.gov (United States)

    Ramsey, J. L.; Walsh, K. F.; Smith, M.; Deegan, J.

    2016-05-01

    With the move to smaller pixel sizes in the longwave IR region there has been a push for shorter focal length lenses that are smaller, cheaper and lighter and that resolve lower spatial frequencies. As a result lenses must have better correction for both chromatic and monochromatic aberrations. This leads to the increased use of aspheres and diffractive optical elements (kinoforms). With recent developments in the molding of chalcogenide materials these aspheres and kinoforms are more cost effective to manufacture. Without kinoforms the axial color can be on the order of 15 μm which degrades the performance of the lens at the Nyquist frequency. The kinoforms are now on smaller elements and are correcting chromatic aberration which is on the order of the design wavelength. This leads to kinoform structures that do not require large phase changes and therefore have 1.5 to just over 2 zones. The question becomes how many zones are required to correct small amounts of chromatic aberration in the system and are they functioning as predicted by the lens design software? We investigate both the design performance and the as-built performance of two designs that incorporate kinoforms for the correction of axial chromatic aberration.

  11. Novel plumage aberrations in Paraguayan non-Passerine Birds, and the definition of a new plumage aberration unique to Psittacidae

    Directory of Open Access Journals (Sweden)

    Paul Smith

    2017-07-01

    Full Text Available Anomalous plumage colourations are reported for three species of non-passerine birds from Paraguay, Limpkin (Aramaus guarauna; Aramidae, Nanday Parakeet (Nandayus nenday; Psittacidae, and the Little Woodpecker (Veniliornis passerinus; Picidae. A leucistic Limpkin is the first published report of a colour anomaly for the family Aramidae. The colour aberration in N. nenday is hypothesised to be a result of an excess of red psittacofulvin pigments, which are unique to the Psittacidae. Although the mechanisms causing this colour aberration remain unknown, we suggest the term psittacofulvism for the phenotypic effect observed.

  12. Thyroid Scan and Uptake

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    Full Text Available ... for a thyroid scan is 30 minutes or less. Thyroid Uptake You will be given radioactive iodine ( ... for each thyroid uptake is five minutes or less. top of page What will I experience during ...

  13. Thyroid Scan and Uptake

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    Full Text Available ... evaluate changes in the gland following medication use, surgery, radiotherapy or chemotherapy top of page How should ... such as an x-ray or CT scan, surgeries or treatments using iodinated contrast material within the ...

  14. Thyroid Scan and Uptake

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    Full Text Available ... abnormal was found, and should not be a cause of concern for you. If you had an ... abnormal was found, and should not be a cause of concern for you. Actual scanning time for ...

  15. Tomographic scanning apparatus

    International Nuclear Information System (INIS)

    1981-01-01

    Details are given of a tomographic scanning apparatus, with particular reference to a multiplexer slip ring means for receiving output from the detectors and enabling interfeed to the image reconstruction station. (U.K.)

  16. Tomographic scanning apparatus

    International Nuclear Information System (INIS)

    1981-01-01

    Details are presented of a tomographic scanning apparatus, its rotational assembly, and the control and circuit elements, with particular reference to the amplifier and multiplexing circuits enabling detector signal calibration. (U.K.)

  17. Tomographic scanning apparatus

    International Nuclear Information System (INIS)

    1981-01-01

    This patent specification relates to a tomographic scanning apparatus using a fan beam and digital output signal, and particularly to the design of the gas-pressurized ionization detection system. (U.K.)

  18. Pediatric CT Scans

    Science.gov (United States)

    The Radiation Epidemiology Branch and collaborators have initiated a retrospective cohort study to evaluate the relationship between radiation exposure from CT scans conducted during childhood and adolescence and the subsequent development of cancer.

  19. Thyroid Scan and Uptake

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    Full Text Available ... which are encased in metal and plastic and most often shaped like a box, attached to a ... will I experience during and after the procedure? Most thyroid scan and thyroid uptake procedures are painless. ...

  20. Heart CT scan

    Science.gov (United States)

    ... make to decrease the risk of heart disease. Risks Risks of CT scans include: Being exposed to ... urac.org). URAC's accreditation program is an independent audit to verify that A.D.A.M. follows ...

  1. Thyroid Scan and Uptake

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    Full Text Available ... eat for several hours before your exam because eating can affect the accuracy of the uptake measurement. ... often unattainable using other imaging procedures. For many diseases, nuclear medicine scans yield the most useful information ...

  2. Thyroid Scan and Uptake

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    Full Text Available ... A thyroid scan is a type of nuclear medicine imaging. The radioactive iodine uptake test (RAIU) is ... thyroid function, but does not involve imaging. Nuclear medicine is a branch of medical imaging that uses ...

  3. Thyroid Scan and Uptake

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    Full Text Available ... that help physicians diagnose and evaluate medical conditions. These imaging scans use radioactive materials called radiopharmaceuticals or ... or had thyroid cancer. A physician may perform these imaging tests to: determine if the gland is ...

  4. Thyroid Scan and Uptake

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    Full Text Available ... Because nuclear medicine procedures are able to pinpoint molecular activity within the body, they offer the potential ... or imaging device that produces pictures and provides molecular information. The thyroid scan and thyroid uptake provide ...

  5. Thyroid Scan and Uptake

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    Full Text Available ... Actual scanning time for each thyroid uptake is five minutes or less. top of page What will ... diagnostic procedures have been used for more than five decades, and there are no known long-term ...

  6. Thyroid Scan and Uptake

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    Full Text Available ... top of page Additional Information and Resources RTAnswers.org Radiation Therapy for Head and Neck Cancer top ... Scan and Uptake Sponsored by Please note RadiologyInfo.org is not a medical facility. Please contact your ...

  7. Thyroid Scan and Uptake

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    Full Text Available ... often unattainable using other imaging procedures. For many diseases, nuclear medicine scans yield the most useful information needed to make a diagnosis or to determine appropriate treatment, if any. Nuclear medicine is less expensive and ...

  8. Thyroid Scan and Uptake

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    Full Text Available ... the gamma camera and single-photon emission-computed tomography (SPECT). The gamma camera, also called a scintillation ... high as with other imaging techniques, such as CT or MRI. However, nuclear medicine scans are more ...

  9. Scanning Auger Electron Microscope

    Data.gov (United States)

    Federal Laboratory Consortium — A JEOL model 7830F field emission source, scanning Auger microscope.Specifications / Capabilities:Ultra-high vacuum (UHV), electron gun range from 0.1 kV to 25 kV,...

  10. Thyroid Scan and Uptake

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    Full Text Available ... as an overactive thyroid gland, a condition called hyperthyroidism , cancer or other growths assess the nature of ... an x-ray or CT scan, surgeries or treatments using iodinated contrast material within the last two ...

  11. Thyroid Scan and Uptake

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    Full Text Available ... painless. However, during the thyroid scan, you may feel uncomfortable when lying completely still with your head ... When the radiotracer is given intravenously, you will feel a slight pin prick when the needle is ...

  12. Thyroid Scan and Uptake

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    Full Text Available ... energy. top of page What are some common uses of the procedure? The thyroid scan is used ... community, you can search the ACR-accredited facilities database . This website does not provide cost information. The ...

  13. Thyroid Scan and Uptake

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    Full Text Available ... scan and thyroid uptake provide information about the structure and function of the thyroid. The thyroid is ... computer, create pictures offering details on both the structure and function of organs and tissues in your ...

  14. Thyroid Scan and Uptake

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    Full Text Available ... found, and should not be a cause of concern for you. If you had an intravenous line ... found, and should not be a cause of concern for you. Actual scanning time for each thyroid ...

  15. Body CT (CAT Scan)

    Science.gov (United States)

    ... a CT scan can be reformatted in multiple planes, and can even generate three-dimensional images. These ... other medical conditions and whether you have a history of heart disease, asthma, diabetes, kidney disease or ...

  16. Thyroid Scan and Uptake

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    Full Text Available ... the gland following medication use, surgery, radiotherapy or chemotherapy top of page How should I prepare? You ... You will receive specific instructions based on the type of scan you are undergoing. top of page ...

  17. Thyroid Scan and Uptake

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    Full Text Available ... Uptake? A thyroid scan is a type of nuclear medicine imaging. The radioactive iodine uptake test (RAIU) ... of thyroid function, but does not involve imaging. Nuclear medicine is a branch of medical imaging that ...

  18. Tomographic scanning apparatus

    International Nuclear Information System (INIS)

    1981-01-01

    This patent specification describes a tomographic scanning apparatus, with particular reference to the adjustable fan beam and its collimator system, together with the facility for taking a conventional x-radiograph without moving the patient. (U.K.)

  19. Thyroid Scan and Uptake

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    Full Text Available ... exam of any medications you are taking, including vitamins and herbal supplements. You should also inform them ... of scan you are undergoing. top of page What does the equipment look like? The special camera ...

  20. The Scanning Optical Microscope.

    Science.gov (United States)

    Sheppard, C. J. R.

    1978-01-01

    Describes the principle of the scanning optical microscope and explains its advantages over the conventional microscope in the improvement of resolution and contrast, as well as the possibility of producing a picture from optical harmonies generated within the specimen.