WorldWideScience

Sample records for cinnabar reconstructive phase

  1. Theoretical studies of the pressure-induced zinc-blende to cinnabar phase transition in CdTe and thermodynamical properties of each phase

    International Nuclear Information System (INIS)

    Luminescence of CdTe quantum dots embedded in ZnTe is quenched at pressure of about 4.5 GPa in the high-pressure experiments. This pressure-induced quenching is attributed to the “zinc-blende–cinnabar” phase transition in CdTe, which was confirmed by the first-principles calculations. Theoretical analysis of the pressure at which the phase transition occurs for CdTe was performed using the CASTEP module of Materials Studio package with both generalized gradient approximation (GGA) and local density approximation (LDA). The calculated phase transition pressures are equal to about 4.4 GPa and 2.6 GPa, according to the GGA and LDA calculations, respectively, which is in a good agreement with the experimental value. Theoretically estimated value of the pressure coefficient of the band-gap luminescence in zinc-blende structure is in very good agreement with that recently measured in the QDs structures. The calculated Debye temperature, elastic constants and specific heat capacity for the zinc-blend structure agree well with the experimental data; the data for the cinnabar phase are reported here for the first time to the best of the authors' knowledge. - Highlights: • Quenching of luminescence of CdTe quantum dots embedded in ZnTe is theoretically explained. • The theoretical calculation of elastic and thermodynamic properties of CdTe by two types of ab-initio methods. • Theoretical calculations of some optical properties of CdTe under pressure in zinc-blende and cinnabar phases

  2. Cinnabar alteration in archaeological wall paintings: an experimental and theoretical approach

    Science.gov (United States)

    Neiman, Madeleine Kegelman; Balonis, Magdalena; Kakoulli, Ioanna

    2015-11-01

    The red mineral pigment known as cinnabar (HgS) was commonly employed in Roman fresco wall paintings. Fresco artists of the period favored this pigment for its striking red color. However, upon excavation and exposure to air and light, cinnabar-pigmented surfaces recovered from archaeological contexts often proved to be unstable. Mural paintings colored with cinnabar that have been exposed in the open air frequently demonstrate a disfiguring, irreversible darkening of the surface. Traditionally, scholars have attributed this alteration to a light-induced phase change from red α-cinnabar to black β-cinnabar (meta-cinnabar). While this transformation has not been totally excluded, the prevailing view among conservation scientists is that chlorine plays a key role in the darkening process through the formation of light-sensitive mercury chloride compounds, or as a catalyst in the photochemical redox of Hg(II)S into Hg(0) and S(0). Using laboratory-based experiments and thermodynamic modeling, this paper attempts to further clarify the mechanism(s) and kinetics of cinnabar alteration in fresco applications, especially the role of light, humidity, and chlorine ions. Additionally, it explores possible pathways and preventive as well as remedial conservation treatments during or immediately following excavation, to inhibit or retard darkening of cinnabar-pigmented fresco surfaces.

  3. Phase Retrieval Versus Phaseless Reconstruction

    OpenAIRE

    Botelho-Andrade, Sara; Casazza, Peter G.; Nguyen, Hanh; Tremain, Janet C.

    2015-01-01

    In 2006, Balan/Casazza/Edidin \\cite{BCE} introduced the frame theoretic study of phaseless reconstruction. Since then, this has turned into a very active area of research. Over the years, many people have replaced the term {\\it phaseless reconstruction} with {\\it phase retrieval}. Casazza then asked: {\\it Are these really the same?} In this paper, we will show that phase retrieval is equivalent to phaseless reconstruction. We then show, more generally, that phase retrieval by projections is e...

  4. On signal reconstruction without noisy phase

    OpenAIRE

    Balan, Radu; Casazza, Pete; Edidin, Dan

    2004-01-01

    We construct new classes of Parseval frames for a Hilbert space which allow signal reconstruction from the absolute value of the frame coefficients. As a consequence, signal reconstruction can be done without using noisy phase or its estimation. This verifies a longstanding conjecture of the speech processing community.

  5. RADON reconstruction in longitudinal phase space

    International Nuclear Information System (INIS)

    Longitudinal particle motion in circular accelerators is typically monitoring by one dimensional (1-D) profiles. Adiabatic particle motion in two dimensional (2-D) phase space can be reconstructed with tomographic techniques, using 1-D profiles. A computer program RADON has been developed in C++ to process digitized mountain range data and perform the phase space reconstruction for the AGS, and later for Relativistic Heavy Ion Collider (RHIC)

  6. PHASE TRANSITION IN SEQUENCE UNIQUE RECONSTRUCTION

    Institute of Scientific and Technical Information of China (English)

    Li XIA; Chan ZHOU

    2007-01-01

    In this paper,sequence unique reconstruction refers to the property that a sequence is uniquely reconstructable from all its K-tuples.We propose and study the phase transition behavior of the probability P(K)of unique reconstruction with regard to tuple size K in random sequences (iid model).Based on Monte Carlo experiments,artificial proteins generated from iid model exhibit a phase transition when P(K)abruptly jumps from a low value phase(e.g.<0.1)to a high value phase (e.g.>0.9).With a generalization to any alphabet,we prove that for a random sequence of length L,as L is large enough,P(K)undergoes a sharp phase transition when P≤0.1015 where p=P(two random letters match).Besides,formulas are derived to estimate the transition points,which may be of practical use in sequencing DNA by hybridization.Concluded from our study,most proteins do not deviate greatly from random sequences in the sense of sequence unique reconstruction,while there are some "stubborn" proteins which only become uniquely reconstructable at a very large K and probably have biological implications.

  7. Interferometric phase reconstruction using simplified coherence network

    Science.gov (United States)

    Zhang, Kui; Song, Ruiqing; Wang, Hui; Wu, Di; Wang, Hua

    2016-09-01

    Interferometric time-series analysis techniques, which extend the traditional differential radar interferometry, have demonstrated a strong capability for monitoring ground surface displacement. Such techniques are able to obtain the temporal evolution of ground deformation within millimeter accuracy by using a stack of synthetic aperture radar (SAR) images. In order to minimize decorrelation between stacked SAR images, the phase reconstruction technique has been developed recently. The main idea of this technique is to reform phase observations along a SAR stack by taking advantage of a maximum likelihood estimator which is defined on the coherence matrix estimated from each target. However, the phase value of a coherence matrix element might be considerably biased when its corresponding coherence is low. In this case, it will turn to an outlying sample affecting the corresponding phase reconstruction process. In order to avoid this problem, a new approach is developed in this paper. This approach considers a coherence matrix element to be an arc in a network. A so-called simplified coherence network (SCN) is constructed to decrease the negative impact of outlying samples. Moreover, a pointed iterative strategy is designed to resolve the transformed phase reconstruction problem defined on a SCN. For validation purposes, the proposed method is applied to 29 real SAR images. The results demonstrate that the proposed method has an excellent computational efficiency and could obtain more reliable phase reconstruction solutions compared to the traditional method using phase triangulation algorithm.

  8. 4D Lung Reconstruction with Phase Optimization

    DEFF Research Database (Denmark)

    Lyksborg, Mark; Paulsen, Rasmus; Brink, Carsten;

    2009-01-01

    This paper investigates and demonstrates a 4D lung CT reconstruction/registration method which results in a complete volumetric model of the lung that deforms according to a respiratory motion field. The motion field is estimated iteratively between all available slice samples and a reference...... than using an optimization which does not correct for phase errors. Knowing how the lung and any tumors located within the lung deforms is relevant in planning the treatment of lung cancer....

  9. Mercury in traditional medicines: Is cinnabar toxicologically similar to common mercurials?

    OpenAIRE

    Liu, Jie; Shi, Jing-Zheng; Yu, Li-Mei; Goyer, Robert A.; Waalkes, Michael P.

    2008-01-01

    Mercury is a major toxic metal ranking top in the Toxic Substances List. Cinnabar (contains mercury sulfide) has been used in traditional medicines for thousands years as an ingredient in various remedies, and 40 cinnabar-containing traditional medicines are still used today. Little is known about toxicology profiles or toxicokinetics of cinnabar and cinnabar-containing traditional medicines, and the high mercury content in these Chinese medicines raises justifiably escalations of public conc...

  10. Reconstruction methods for phase-contrast tomography

    Energy Technology Data Exchange (ETDEWEB)

    Raven, C.

    1997-02-01

    Phase contrast imaging with coherent x-rays can be distinguished in outline imaging and holography, depending on the wavelength {lambda}, the object size d and the object-to-detector distance r. When r << d{sup 2}{lambda}, phase contrast occurs only in regions where the refractive index fastly changes, i.e. at interfaces and edges in the sample. With increasing object-to-detector distance we come in the area of holographic imaging. The image contrast outside the shadow region of the object is due to interference of the direct, undiffracted beam and a beam diffracted by the object, or, in terms of holography, the interference of a reference wave with the object wave. Both, outline imaging and holography, offer the possibility to obtain three dimensional information of the sample in conjunction with a tomographic technique. But the data treatment and the kind of information one can obtain from the reconstruction is different.

  11. Adsorption of I- ions on cinnabar for 129I waste management

    International Nuclear Information System (INIS)

    Adsorption of I- ions on natural cinnabars, whose localities are Spain, USA, and Mexico, have been studied by batch method. Only Spain cinnabar (S-cinnabar) was found to have relatively high adsorptivity to I- ions even in the presence of Cl- ions. The value of distribution ratio (Kd) is 103 ml/g under the conditions of initial [I-] = 1.0 x 10-6 M (1 M = 1 mol/dm3), pH 6.0, and solution/S-cinnabar = 100 ml/g. It was found that the adsorptivities of S-cinnabar to I- ions increase with an increase in the specific surface area and a decrease in pH, that the adsorption of I- ions on S-cinnabar is irreversible, and that S-cinnabars heated at temperatures higher than 100 C decrease the adsorptivities to I- ions. Furthermore, I- ions were found to be not adsorbed on HgS reagent which is the main component of cinnabar. From these results, the adsorption of I- ions on S-cinnabar is considered to be due to the reaction between I- ions and certain species in the surface, which are thermally unstable and minor component. (orig.)

  12. Using a plenoptic sensor to reconstruct vortex phase structures.

    Science.gov (United States)

    Wu, Chensheng; Ko, Jonathan; Davis, Christopher C

    2016-07-15

    A branch point problem and its solution commonly involve recognizing and reconstructing a vortex phase structure around a singular point. In laser beam propagation through random media, the destructive phase contributions from various parts of a vortex phase structure will cause a dark area in the center of the beam's intensity profile. This null of intensity can, in turn, prevent the vortex phase structure from being recognized. In this Letter, we show how to use a plenoptic sensor to transform the light field of a vortex beam so that a simple and direct reconstruction algorithm can be applied to reveal the vortex phase structure. As a result, we show that the plenoptic sensor is effective in detecting branch points and can be used to reconstruct phase distortion in a beam in a wide sense. PMID:27420487

  13. Noise robustness of a combined phase retrieval and reconstruction method for phase-contrast tomography

    DEFF Research Database (Denmark)

    Kongskov, Rasmus Dalgas; Jørgensen, Jakob Sauer; Poulsen, Henning Friis;

    2016-01-01

    Classical reconstruction methods for phase-contrast tomography consist of two stages: phase retrieval and tomographic reconstruction. A novel algebraic method combining the two was suggested by Kostenko et al. [Opt. Express 21, 12185 (2013) [CrossRef], and preliminary results demonstrated improve...

  14. Cinnabar, arsenian pyrite and thallium-enrichment in active shallow submarine hydrothermal vents at Paleochori Bay, Milos Island, Greece

    Science.gov (United States)

    Kati, Marianna; Voudouris, Panagiotis; Valsami-Jones, Eugenia; Magganas, Andreas; Baltatzis, Emmanouil; Kanellopoulos, Christos; Mavrogonatos, Constantinos

    2015-04-01

    We herein report the discovery of active cinnabar-depositing hydrothermal vents in a submarine setting at Paleochori Bay, within the offshore southeastern extension of the Milos Island Geothermal Field, South Aegean Active Volcanic Arc. Active, low temperature (up to 115 °C) hydrothermal venting through volcaniclastic material has led to a varied assemblage of sulfide and alteration mineral phases in an area of approximately 1 km2. Our samples recovered from Paleochori Bay are hydrothermal edifices composed of volcaniclastic detrital material cemented by pyrite, or pure sulfide (mainly massive pyrite) mounts. Besides pyrite and minor marcasite, the hydrothermal minerals include cinnabar, amorphous silica, hydrous ferric oxides, carbonates (aragonite and calcite), alunite-jarosite solid solution and Sr-rich barite. Among others, growth textures, sieve-textured pyrite associated with barite, alunite-jarosite solid solution and hydrous ferric oxides rims colloform-banded pyrite layers. Overgrowths of arsenian pyrite layers (up to 3.2 wt. % As and/or up to 1.1 wt. % Mn) onto As-free pyrite indicate fluctuation in As content of the hydrothermal fluid. Mercury, in the form of cinnabar, occurs in up to 5 μm grains within arsenian pyrite layers, usually forming distinct cinnabar-enriched micro-layers. Hydrothermal Sr-rich barite (barite-celestine solid solution), pseudocubic alunite-jarosite solid solution and Mn- and Sr-enriched carbonates occur in various amounts and closely associated with pyrite and/or hydrous ferric oxides. Thallium-bearing sulfides and/or sulfosalts were not detected during our study; however, hydrous ferric oxides show thallium content of up to 0.5 wt. % Tl. The following scenarios may have played a role in pyrite precipitation at Paleochori: (a) H2S originally dissolved in the deep fluid but separated upon boiling could have reacted with oxygenated seawater under production of sulphuric acid, thus causing leaching and dissolution of primary iron

  15. Phase Transition in Distance-Based Phylogeny Reconstruction

    CERN Document Server

    Roch, Sebastien

    2011-01-01

    We introduce a new distance-based phylogeny reconstruction technique which provably achieves, at sufficiently short branch lengths, a logarithmic sequence-length requirement---improving significantly over previous polynomial bounds for distance-based methods and matching existing results for general methods. The technique is based on an averaging procedure that implicitly reconstructs ancestral sequences. In the same token, we extend previous results on phase transitions in phylogeny reconstruction to general time-reversible models. More precisely, we show that in the so-called Kesten-Stigum zone (roughly, a region of the parameter space where ancestral sequences are well approximated by "linear combinations" of the observed sequences) sequences of length $O(\\log n)$ suffice for reconstruction when branch lengths are discretized. Here $n$ is the number of extant species. Our results challenge, to some extent, the conventional wisdom that estimates of evolutionary distances alone carry significantly less infor...

  16. Cinnabar presence ar round the Valentin stream in Florida district of Uruguay

    International Nuclear Information System (INIS)

    Some little grains of cinnabar were found in Valentin River, Florida, Uruguay during the Gold Exploration Project on the Area in 1991. We present some chemical data to prove the existence of mercury probably related to a greissen hydrothermal event.

  17. Cinnabar-Induced Subchronic Renal Injury Is Associated with Increased Apoptosis in Rats

    Directory of Open Access Journals (Sweden)

    Ying Wang

    2015-01-01

    Full Text Available The aim of this study was to explore the role of apoptosis in cinnabar-induced renal injury in rats. To test this role, rats were dosed orally with cinnabar (1 g/kg/day for 8 weeks or 12 weeks, and the control rats were treated with 5% carboxymethylcellulose solution. Levels of urinary mercury (UHg, renal mercury (RHg, serum creatinine (SCr, and urine kidney injury molecule 1 (KIM-1 were assessed, and renal pathology was analyzed. Apoptotic cells were identified and the apoptotic index was calculated. A rat antibody array was used to analyze expression of cytokines associated with apoptosis. Results from these analyses showed that UHg, RHg, and urine KIM-1, but not SCr, levels were significantly increased in cinnabar-treated rats. Renal pathological changes in cinnabar-treated rats included vacuolization of tubular cells, formation of protein casts, infiltration of inflammatory cells, and increase in the number of apoptotic tubular cells. In comparison to the control group, expression of FasL, Fas, TNF-α, TRAIL, activin A, and adiponectin was upregulated in the cinnabar-treated group. Collectively, our results suggest that prolonged use of cinnabar results in kidney damage due to accumulation of mercury and that the underlying mechanism involves apoptosis of tubular cells via a death receptor-mediated pathway.

  18. On simulated annealing phase transitions in phylogeny reconstruction.

    Science.gov (United States)

    Strobl, Maximilian A R; Barker, Daniel

    2016-08-01

    Phylogeny reconstruction with global criteria is NP-complete or NP-hard, hence in general requires a heuristic search. We investigate the powerful, physically inspired, general-purpose heuristic simulated annealing, applied to phylogeny reconstruction. Simulated annealing mimics the physical process of annealing, where a liquid is gently cooled to form a crystal. During the search, periods of elevated specific heat occur, analogous to physical phase transitions. These simulated annealing phase transitions play a crucial role in the outcome of the search. Nevertheless, they have received comparably little attention, for phylogeny or other optimisation problems. We analyse simulated annealing phase transitions during searches for the optimal phylogenetic tree for 34 real-world multiple alignments. In the same way in which melting temperatures differ between materials, we observe distinct specific heat profiles for each input file. We propose this reflects differences in the search landscape and can serve as a measure for problem difficulty and for suitability of the algorithm's parameters. We discuss application in algorithmic optimisation and as a diagnostic to assess parameterisation before computationally costly, large phylogeny reconstructions are launched. Whilst the focus here lies on phylogeny reconstruction under maximum parsimony, it is plausible that our results are more widely applicable to optimisation procedures in science and industry. PMID:27150349

  19. Phase 1 of the Hanford Environmental Dose Reconstruction Project

    Energy Technology Data Exchange (ETDEWEB)

    1991-08-01

    The work described in this report was prompted by the public's concern about potential effect from the radioactive materials released from the Hanford Site. The Hanford Environmental Dose Reconstruction (HEDR) Project was established to estimate radiation dose the public might have received from the Hanford Site since 1944, when facilities began operating. Phase 1 of the HEDR Project is a pilot'' or demonstration'' phase. The objectives of this initial phase were to determine whether enough historical information could be found or reconstructed to be used for dose estimation and develop and test conceptual and computational models for calculating credible dose estimates. Preliminary estimates of radiation doses were produced in Phase 1 because they are needed to achieve these objectives. The reader is cautioned that the dose estimates provided in this and other Phase 1 HEDR reports are preliminary. As the HEDR Project continues, the dose estimates will change for at least three reasons: more complete input information for models will be developed; the models themselves will be refined; and the size and shape of the geographic study area will change. This is one of three draft reports that summarize the first phase of the four-phased HEDR Project. This, the Summary Report, is directed to readers who want a general understanding of the Phase 1 work and preliminary dose estimates. The two other reports -- the Air Pathway Report and the Columbia River Pathway Report -- are for readers who understand the radiation dose assessment process and want to see more technical detail. Detailed descriptions of the dose reconstruction process are available in more than 20 supporting reports listed in Appendix A. 32 refs., 46 figs.

  20. Phase 1 of the Hanford Environmental Dose Reconstruction Project

    International Nuclear Information System (INIS)

    The work described in this report was prompted by the public's concern about potential effect from the radioactive materials released from the Hanford Site. The Hanford Environmental Dose Reconstruction (HEDR) Project was established to estimate radiation dose the public might have received from the Hanford Site since 1944, when facilities began operating. Phase 1 of the HEDR Project is a ''pilot'' or ''demonstration'' phase. The objectives of this initial phase were to determine whether enough historical information could be found or reconstructed to be used for dose estimation and develop and test conceptual and computational models for calculating credible dose estimates. Preliminary estimates of radiation doses were produced in Phase 1 because they are needed to achieve these objectives. The reader is cautioned that the dose estimates provided in this and other Phase 1 HEDR reports are preliminary. As the HEDR Project continues, the dose estimates will change for at least three reasons: more complete input information for models will be developed; the models themselves will be refined; and the size and shape of the geographic study area will change. This is one of three draft reports that summarize the first phase of the four-phased HEDR Project. This, the Summary Report, is directed to readers who want a general understanding of the Phase 1 work and preliminary dose estimates. The two other reports -- the Air Pathway Report and the Columbia River Pathway Report -- are for readers who understand the radiation dose assessment process and want to see more technical detail. Detailed descriptions of the dose reconstruction process are available in more than 20 supporting reports listed in Appendix A. 32 refs., 46 figs

  1. Phase reconstruction from intensity measurements in linear systems.

    Science.gov (United States)

    Bastiaans, Martin J; Wolf, Kurt Bernardo

    2003-06-01

    The phase of a signal at a plane is reconstructed from the intensity profiles at two close parallel screens connected by a small abcd canonical transform; this applies to propagation along harmonic and repulsive fibers and in free media. We analyze the relationship between the local spatial frequency (the signal phase derivative) and the derivative of the squared modulus of the signal under a one-parameter canonical transform with respect to the parameter. We thus generalize to all linear systems the results that have been obtained separately for Fresnel and fractional Fourier transforms. PMID:12801172

  2. Holographic and weak-phase projection system for 3D shape reconstruction using temporal phase unwrapping

    Science.gov (United States)

    González, C. A.; Dávila, A.; Garnica, G.

    2007-09-01

    Two projection systems that use an LCoS phase modulator are proposed for 3D shape reconstruction. The LCoS is used as an holographic system or as a weak phase projector, both configurations project a set of fringe patterns that are processed by the technique known as temporal phase unwrapping. To minimize the influence of camera sampling, and the speckle noise in the projected fringes, an speckle noise reduction technique is applied to the speckle patterns generated by the holographic optical system. Experiments with 3D shape reconstruction of ophthalmic mold and other testing specimens show the viability of the proposed techniques.

  3. Phase 1 of the Hanford Environmental Dose Reconstruction Project

    Energy Technology Data Exchange (ETDEWEB)

    1990-07-20

    For more than 40 years, the US government made plutonium for nuclear weapons at the Hanford Site in southeastern Washington State. Radioactive materials were released to both the air and water from Hanford. People could have been exposed to these materials, called radionuclides. The Hanford Environmental Dose Reconstruction (HEDR) Project is a multi-year scientific study to estimate the radiation doses the public may have received as a results of these releases. The study began in 1988. During the first phase, scientists began to develop and test methods for reconstructing the radiation doses. To do this, scientists found or reconstructed information about the amount and type of radionuclides that were released from Hadford facilities, where they traveled in environment, and how they reached people. Information about the people who could have been exposed was also found or reconstructed. Scientists then developed a computer model that can estimate doses from radiation exposure received many years ago. All the information that had been gathered was fed into the computer model. Then scientists did a test run'' to see whether the model was working properly. As part of its test run,'' scientists asked the computer model to generate two types of preliminary results: amounts of radionuclides in the environment (air, soil, pasture grass, food, and milk) and preliminary doses people could have received from all the routes of radiation exposure, called exposure pathways. Preliminary dose estimates were made for categories of people who shared certain characteristics and for the Phase 1 population as a whole. 26 refs., 48 figs.

  4. Quantitative phase reconstruction for orthogonal-scanning differential phase-contrast optical coherence tomography

    CERN Document Server

    Heise, Bettina; 10.1364/OL.34.001306

    2011-01-01

    We present differential phase-contrast optical coherence tomography (DPC-OCT) with two transversally separated probing beams to sense phase gradients in various directions by employing a rotatable Wollaston prism. In combination with a two-dimensional mathe- matical reconstruction algorithm based on a regularized shape from shading (SfS) method accurate quantitative phase maps can be determined from a set of two orthogonal en-face DPC-OCT images, as exemplified on various technical samples.

  5. Performance validation of phase diversity image reconstruction techniques

    Science.gov (United States)

    Hirzberger, J.; Feller, A.; Riethmüller, T. L.; Gandorfer, A.; Solanki, S. K.

    2011-05-01

    We present a performance study of a phase diversity (PD) image reconstruction algorithm based on artificial solar images obtained from MHD simulations and on seeing-free data obtained with the SuFI instrument on the Sunrise balloon borne observatory. The artificial data were altered by applying different levels of degradation with synthesised wavefront errors and noise. The PD algorithm was modified by changing the number of fitted polynomials, the shape of the pupil and the applied noise filter. The obtained reconstructions are evaluated by means of the resulting rms intensity contrast and by the conspicuousness of appearing artifacts. The results show that PD is a robust method which consistently recovers the initial unaffected image contents. The efficiency of the reconstruction is, however, strongly dependent on the number of used fitting polynomials and the noise level of the images. If the maximum number of fitted polynomials is higher than 21, artifacts have to be accepted and for noise levels higher than 10-3 the commonly used noise filtering techniques are not able to avoid amplification of spurious structures.

  6. BACILLUS THURINGIENSIS VAR. KURSTAKI AFFECTS A BENEFICIAL INSECT, THE CINNABAR MOTH (LEPIDOPTERA: ARCTIIDAE)

    Science.gov (United States)

    The microbial insecticide bacillus thuringiensis Berliner var. kurstaki is used to control forest pests in regions where tansy ragwort, Senecio jacobaea L. occurs. iological control of this noxious weed may be compromised if the cinnabar moth, Tyria jacobaeae (L), is susceptible ...

  7. Simultaneous maximum-likelihood reconstruction for x-ray grating based phase-contrast tomography avoiding intermediate phase retrieval

    CERN Document Server

    Ritter, André; Durst, Jürgen; Gödel, Karl; Haas, Wilhelm; Michel, Thilo; Rieger, Jens; Weber, Thomas; Wucherer, Lukas; Anton, Gisela

    2013-01-01

    Phase-wrapping artifacts, statistical image noise and the need for a minimum amount of phase steps per projection limit the practicability of x-ray grating based phase-contrast tomography, when using filtered back projection reconstruction. For conventional x-ray computed tomography, the use of statistical iterative reconstruction algorithms has successfully reduced artifacts and statistical issues. In this work, an iterative reconstruction method for grating based phase-contrast tomography is presented. The method avoids the intermediate retrieval of absorption, differential phase and dark field projections. It directly reconstructs tomographic cross sections from phase stepping projections by the use of a forward projecting imaging model and an appropriate likelihood function. The likelihood function is then maximized with an iterative algorithm. The presented method is tested with tomographic data obtained through a wave field simulation of grating based phase-contrast tomography. The reconstruction result...

  8. Neurotoxicological effects of cinnabar (a Chinese mineral medicine, HgS) in mice

    International Nuclear Information System (INIS)

    Cinnabar, a naturally occurring mercuric sulfide (HgS), has long been used in combination with traditional Chinese medicine as a sedative for more than 2000 years. Up to date, its pharmacological and toxicological effects are still unclear, especially in clinical low-dose and long-term use. In this study, we attempted to elucidate the effects of cinnabar on the time course of changes in locomotor activities, pentobarbital-induced sleeping time, motor equilibrium performance and neurobiochemical activities in mice during 3- to 11-week administration at a clinical dose of 10 mg/kg/day. The results showed that cinnabar was significantly absorbed by gastrointestinal (G-I) tract and transported to brain tissues. The spontaneous locomotor activities of male mice but not female mice were preferentially suppressed. Moreover, frequencies of jump and stereotype-1 episodes were progressively decreased after 3-week oral administration in male and female mice. Pentobarbital-induced sleeping time was prolonged and the retention time on a rotating rod (60 rpm) was reduced after treatment with cinnabar for 6 weeks and then progressively to a greater extent until the 11-week experiment. In addition, the biochemical changes in blood and brain tissues were studied; the inhibition of Na+/K+-ATPase activities, increased production of lipid peroxidation (LPO) and nitric oxide (NO) were found with a greater extent in male mice than those in female mice, which were apparently correlated with their differences in the neurological responses observed. In conclusion, these findings, for the first time, provide evidence of the pharmacological and toxicological basis for understanding the sedative and neurotoxic effects of cinnabar used as a Chinese mineral medicine for more than 2000 years

  9. Optical correlation algorithm for reconstructing phase skeleton of complex optical fields for solving the phase problem

    DEFF Research Database (Denmark)

    Angelsky, O. V.; Gorsky, M. P.; Hanson, Steen Grüner;

    2014-01-01

    We propose an optical correlation algorithm illustrating a new general method for reconstructing the phase skeleton of complex optical fields from the measured two-dimensional intensity distribution. The core of the algorithm consists in locating the saddle points of the intensity distribution and...... connecting such points into nets by the lines of intensity gradient that are closely associated with the equi-phase lines of the field. This algorithm provides a new partial solution to the inverse problem in optics commonly referred to as the phase problem....

  10. The holographic reconstructing algorithm and its error analysis about phase-shifting phase measurement

    Institute of Scientific and Technical Information of China (English)

    LU Xiaoxu; ZHONG Liyun; ZHANG Yimo

    2007-01-01

    Phase-shifting measurement and its error estimation method were studied according to the holographic principle.A function of synchronous superposition of object complex amplitude reconstructed from N-step phase-shifting through one integral period (N-step phase-shifting function for short) was proposed.In N-step phase-shifting measurement,the interferograms are seen as a series of in-line holograms and the reference beam is an ideal parallel-plane wave.So the N-step phase-shifting function can be obtained by multiplying the interferogram by the original referencc wave.In ideal conditions.the proposed method is a kind of synchronous superposition algorithm in which the complex amplitude is separated,measured and superposed.When error exists in measurement,the result of the N-step phase-shifting function is the optimal expected value of the least-squares fitting method.In the above method,the N+1-step phase-shifting function can be obtained from the N-step phase-shifting function.It shows that the N-step phase-shifting function can be separated into two parts:the ideal N-step phase-shifting function and its errors.The phase-shifting errors in N-steps phase-shifting phase measurement can be treated the same as the relative errors of amplitude and intensity under the understanding of the N+1-step phase-shifting function.The difficulties of the error estimation in phase-shifting phase measurement were restricted by this error estimation method.Meanwhile,the maximum error estimation method of phase-shifting phase measurement and its formula were proposed.

  11. Single Shot Digital Holography Using Iterative Reconstruction with Alternating Updates of Amplitude and Phase

    CERN Document Server

    Lee, Dennis J; Weiner, Andrew M

    2016-01-01

    We present an image recovery approach to improve amplitude and phase reconstruction from single shot digital holograms, using iterative reconstruction with alternating updates. This approach allows the flexibility to apply different priors to amplitude and phase, improves phase reconstruction in image areas with low amplitudes, and does not require phase unwrapping for regularization. Phantom simulations and experimental measurements of a grating sample both demonstrate that the proposed method helps to reduce noise and resolve finer features. The improved image reconstruction from this technique will benefit the many applications of digital holography.

  12. Evaluation of hepatotoxicity potential of cinnabar-containing An-Gong-Niu-Huang Wan, a patent traditional Chinese medicine.

    Science.gov (United States)

    Lu, Yuan-Fu; Wu, Qin; Liang, Shi-Xia; Miao, Jia-Wei; Shi, Jing-Shan; Liu, Jie

    2011-07-01

    An-Gong-Niu-Huang Wan (AGNH) is a patent traditional Chinese medicine for brain disorders. It contains 10% cinnabar (HgS). Hg is known to produce toxicity to the kidney, brain and liver. Is AGNH safe? Liver is a major organ for drug metabolism, whether the long-term use of AGNH would affect hepatic P450 enzymes is unknown. To address these concerns, mice were given orally cinnabar (300mg/kg), cinnabar-containing AGNH daily for 44days, and liver toxicity was examined and compared with that of methylmercury (MeHg, 2.6mg/kg) and mercuric chloride (HgCl(2), 32mg/kg). Serum aminotransferases were increased by MeHg and HgCl(2) only. Histopathology showed more severe liver damage in MeHg- and HgCl(2)-treated mice than in the cinnabar and AGNH groups. Accumulation of Hg in MeHg- and HgCl(2)-treated mice was 96- and 71-fold higher than controls, respectively, but was only 2-fold after cinnabar and AGNH administration. Expressions of metallothionein-1 and heme oxygenase-1, biomarkers for Hg toxicity, were increased by MeHg and HgCl(2,) but were not altered in cinnabar- and AGNH-treated mice. Expression of hepatic cytochrome P450 genes, such as Cyp1a1, Cyp1b1 and Cyp4a10 was increased only after MeHg and HgCl(2), and the expressions of Cyp3a11and Cyp3a25 were increased by all treatments, indicating the potential Hg-drug interactions after long-term use of cinnabar-containing traditional medicines. Taken together, the results demonstrate that AGNH is much less hepatotoxic than common mercurials, and that the use of total Hg content to evaluate the toxicity of cinnabar-containing traditional Chinese medicines appears to be inappropriate. PMID:21435368

  13. Chronic mercury exposure in Late Neolithic/Chalcolithic populations in Portugal from the cultural use of cinnabar

    Science.gov (United States)

    Emslie, Steven D.; Brasso, Rebecka; Patterson, William P.; Carlos Valera, António; McKenzie, Ashley; Maria Silva, Ana; Gleason, James D.; Blum, Joel D.

    2015-10-01

    Cinnabar is a natural mercury sulfide (HgS) mineral of volcanic or hydrothermal origin that is found worldwide. It has been mined prehistorically and historically in China, Japan, Europe, and the Americas to extract metallic mercury (Hg0) for use in metallurgy, as a medicinal, a preservative, and as a red pigment for body paint and ceramics. Processing cinnabar via combustion releases Hg0 vapor that can be toxic if inhaled. Mercury from cinnabar can also be absorbed through the gut and skin, where it can accumulate in organs and bone. Here, we report moderate to high levels of total mercury (THg) in human bone from three Late Neolithic/Chalcolithic (5400-4100 B.P.) sites in southern Portugal that were likely caused by cultural use of cinnabar. We use light stable isotope and Hg stable isotope tracking to test three hypotheses on the origin of mercury in this prehistoric human bone. We traced Hg in two individuals to cinnabar deposits near Almadén, Spain, and conclude that use of this mineral likely caused mild to severe mercury poisoning in the prehistoric population. Our methods have applications to bioarchaeological investigations worldwide, and for tracking trade routes and mobility of prehistoric populations where cinnabar use is documented.

  14. Analysis of reconstructed interference fields in digital holographic interferometry using the polynomial phase transform

    International Nuclear Information System (INIS)

    A noisy wrapped phase map is the end-output of commonly employed phase estimation methods in digital holographic interferometry. Hence filtering and unwrapping are necessary to obtain continuous phase distributions. This paper introduces a new approach for phase estimation in digital holographic interferometry using the polynomial phase transform. The proposed approach directly provides an accurate estimation of the unwrapped phase distribution from a noisy reconstructed interference field, thereby bypassing cumbersome and error-prone filtering and 2D phase unwrapping procedures

  15. Direct phase shift extraction and wavefront reconstruction in two-step generalized phase-shifting interferometry

    International Nuclear Information System (INIS)

    A direct phase shift extraction and wavefront reconstruction method in two-step generalized phase-shifting interferometry (GPSI) with arbitrary unknown phase shift is proposed. In this method the unknown phase shift α can be extracted by a determinate formula directly without iteration or additional judgment of its correct value from two or more phase shift solutions as necessary before. By an appropriate formula of GPSI the complex object field in the recording plane can be calculated and then the object wavefront in the original object plane obtained. This method is applicable for GPSI of any frame number K≥2 and for both the amplitude and phase objects. Computer simulations have shown that the phase shift extraction errors are below 0.01 rad in a wide range of 0.4 rad<α<2.6 rad and the computation time is greatly reduced by a factor of about 20 compared with the previous method. The effectiveness and accuracy of this method are also verified by optical experiments

  16. Modeling of effect of LC SLM phase fluctuations on kinoforms optical reconstruction quality

    Science.gov (United States)

    Cheremkhin, Pavel A.; Evtikhiev, Nikolay N.; Krasnov, Vitaly V.; Rodin, Vladislav G.; Starikov, Sergey N.

    2015-05-01

    Phase-only liquid crystal (LC) spatial light modulators (SLM) are actively used in various applications. However, majority of scientific applications require stable phase modulation which might be hard to achieve with commercially available SLM due to its consumer origin. The use of digital voltage addressing scheme leads to phase temporal fluctuations, which results in lower diffraction efficiency and reconstruction quality of displayed diffractive optical elements (DOE). It is often preferable to know effect of these fluctuations on DOE reconstruction quality before SLM is implemented into experimental setup. It is especially important in case of multi-level phaseonly DOE such as kinoforms. Therefore we report results of modeling of effect of phase fluctuations of LC SLM "HoloEye PLUTO VIS" on kinoforms optical reconstruction quality. Modeling was conducted in the following way. First dependency of LC SLM phase shift on addressed signal level and time from frame start was measured for all signal values (0-255) with temporal resolution of 0.5 ms in time period of one frame. Then numerical simulation of effect of SLM phase fluctuations on kinoforms reconstruction quality was performed. Based on measured dependency, for each time delay new distorted kinoform was generated and then numerically reconstructed. Averaged reconstructed image corresponds to optically reconstructed one with registration time exceeding time period of one frame (16.7 ms), while individual images correspond to momentary optical reconstruction with registration time less than 1 ms. Quality degradation of modeled optical reconstruction of several test kinoforms was analyzed. Comparison of kinoforms optical reconstruction with SLM and numerically simulated reconstruction was conducted.

  17. Coronary CT angiography: automatic cardiac-phase selection for image reconstruction

    Energy Technology Data Exchange (ETDEWEB)

    Ruzsics, Balazs; Brothers, Robin L.; Costello, Philip [Medical University of South Carolina, Department of Radiology and Radiological Science, Charleston, SC (United States); Gebregziabher, Mulugeta [Medical University of South Carolina, Department of Biostatistics, Bioinformatics, and Epidemiology, Charleston, SC (United States); Lee, Heon [Medical University of South Carolina, Department of Radiology and Radiological Science, Charleston, SC (United States); Seoul Medical Center, Department of Radiology, Seoul (Korea); Allmendinger, Thomas; Vogt, Sebastian [Siemens Medical Solutions, Division CT, Forchheim (Germany); Schoepf, U.J. [Medical University of South Carolina, Department of Radiology and Radiological Science, Charleston, SC (United States); Medical University of South Carolina, Division of Cardiology, Charleston, SC (United States)

    2009-08-15

    We evaluated an algorithm for automatic selection of the cardiac phase with the least motion for image reconstruction at coronary computed tomography (CT) angiography (CCTA). We analyzed data of 100 patients (49 female, mean age 59 years) who had undergone retrospectively ECG-gated CCTA. Two experienced observers visually identified the most suitable end-systolic and end-diastolic phases using a series of image reconstructions in 5% increments across the RR cycle. The same data were then reconstructed using an automatic phase finding algorithm based on a 4D weighting function of cardiac motion. On average, the algorithm determined the most suitable systolic reconstruction phase at 40.11{+-}6.29% RR compared with 40.07{+-}5.58% RR by the human observers (p=NS). The most suitable diastolic phase was found at 72.71{+-}7.37% RR by the automatic algorithm, compared with 76.43{+-}6.35% RR by the observers (p<0.05). No statistically significant difference was found between automatically and visually determined reconstruction phases regarding motion and stair-step artifacts in either systole or diastole (p>0.05). Thus, there appears to be no relevant difference between an automatic phase finding algorithm and visual selection by experienced observers for determining the phase with the least cardiac motion for CCTA image reconstruction. The use of automatic phase finding may therefore facilitate the performance of cardiac CT and reduce human error. (orig.)

  18. A feasibility study for compressed sensing combined phase contrast MR angiography reconstruction

    Science.gov (United States)

    Lee, Dong-Hoon; Hong, Cheol-Pyo; Lee, Man-Woo; Han, Bong-Soo

    2012-02-01

    Phase contrast magnetic resonance angiography (PC MRA) is a technique for flow velocity measurement and vessels visualization, simultaneously. The PC MRA takes long scan time because each flow encoding gradients which are composed bipolar gradient type need to reconstruct the angiography image. Moreover, it takes more image acquisition time when we use the PC MRA at the low-tesla MRI system. In this study, we studied and evaluation of feasibility for CS MRI reconstruction combined PC MRA which data acquired by low-tesla MRI system. We used non-linear reconstruction algorithm which named Bregman iteration for CS image reconstruction and validate the usefulness of CS combined PC MRA reconstruction technique. The results of CS reconstructed PC MRA images provide similar level of image quality between fully sampled reconstruction data and sparse sampled reconstruction using CS technique. Although our results used half of sampling ratio and do not used specification hardware device or performance which are improving the temporal resolution of MR image acquisition such as parallel imaging reconstruction using phased array coil or non-cartesian trajectory, we think that CS combined PC MRA technique will be helpful to increase the temporal resolution and at low-tesla MRI system.

  19. Iterative reconstruction in x-ray computed laminography from differential phase measurements

    Science.gov (United States)

    Harasse, Sébastien; Yashiro, Wataru; Momose, Atsushi

    2011-08-01

    Phase-contrast X-ray computed laminography is demonstrated for the volume reconstruction of extended flat objects, not suitable to the usual tomographic scan. Using a Talbot interferometer, differential phase measurements are obtained and used to reconstruct the real part of the complex refractive index. The specific geometry of laminography leads to unsampled frequencies in a double cone in the reciprocal space, which degrades the spatial resolution in the direction normal to the object plane. First, the filtered backprojection formula from differential measurements is derived. Then, reconstruction is improved by the use of prior information of compact support and limited range, included in an iterative filtered backprojection algorithm. An implementation on GPU hardware was required to handle the reconstruction of volumes within a reasonable time. A synchrotron radiation experiment on polymer meshes is reported and results of the iterative reconstruction are compared with the simpler filtered backprojection.

  20. Filling factor characteristics of masking phase-only hologram on the quality of reconstructed images

    Science.gov (United States)

    Deng, Yuanbo; Chu, Daping

    2016-03-01

    The present study evaluates the filling factor characteristics of masking phase-only hologram on its corresponding reconstructed image. A square aperture with different filling factor is added on the phase-only hologram of the target image, and average cross-section intensity profile of the reconstructed image is obtained and deconvolved with that of the target image to calculate the point spread function (PSF) of the image. Meanwhile, Lena image is used as the target image and evaluated by metrics RMSE and SSIM to assess the quality of reconstructed image. The results show that the PSF of the image agrees with the PSF of the Fourier transform of the mask, and as the filling factor of the mask decreases, the width of PSF increases and the quality of reconstructed image drops. These characteristics could be used in practical situations where phase-only hologram is confined or need to be sliced or tiled.

  1. Explicit Filtering Based Low-Dose Differential Phase Reconstruction Algorithm with the Grating Interferometry

    Directory of Open Access Journals (Sweden)

    Xiaolei Jiang

    2015-01-01

    Full Text Available X-ray grating interferometry offers a novel framework for the study of weakly absorbing samples. Three kinds of information, that is, the attenuation, differential phase contrast (DPC, and dark-field images, can be obtained after a single scanning, providing additional and complementary information to the conventional attenuation image. Phase shifts of X-rays are measured by the DPC method; hence, DPC-CT reconstructs refraction indexes rather than attenuation coefficients. In this work, we propose an explicit filtering based low-dose differential phase reconstruction algorithm, which enables reconstruction from reduced scanning without artifacts. The algorithm adopts a differential algebraic reconstruction technique (DART with the explicit filtering based sparse regularization rather than the commonly used total variation (TV method. Both the numerical simulation and the biological sample experiment demonstrate the feasibility of the proposed algorithm.

  2. Phase Response of Fine Frequency Grid Reconstruction of Sampling Oscilloscopes Based on the NTN Calibration

    OpenAIRE

    Zhang Yichi; Lin Maoliu; Xu Qinghua

    2011-01-01

    This study describes an algorithm for determining the fine phase response of equivalent sampling oscilloscopes of a linear time-invariant response function from its magnitude. The Nose-to-Nose (NTN) calibration method can give the phase response of the equivalent sampling oscilloscopes, but the phase resolution can only achieve 250 MHz because the limit of the technology. In this study the fine phase response has been reconstructed. Although the truncation of the Kramers-Kronig transform usin...

  3. Phase-selective image reconstruction of the lungs in small animals using micro-CT

    Science.gov (United States)

    Johnston, S. M.; Perez, B. A.; Kirsch, D. G.; Badea, C. T.

    2010-04-01

    Gating in small animal imaging can compensate for artifacts due to physiological motion. This paper presents a strategy for sampling and image reconstruction in the rodent lung using micro-CT. The approach involves rapid sampling of freebreathing mice without any additional hardware to detect respiratory motion. The projection images are analyzed postacquisition to derive a respiratory signal, which is used to provide weighting factors for each projection that favor a selected phase of the respiration (e.g. end-inspiration or end-expiration) for the reconstruction. Since the sampling cycle and the respiratory cycle are uncorrelated, the sets of projections corresponding to any of the selected respiratory phases do not have a regular angular distribution. This drastically affects the image quality of reconstructions based on simple filtered backprojection. To address this problem, we use an iterative reconstruction algorithm that combines the Simultaneous Algebraic Reconstruction Technique with Total Variation minimization (SART-TV). At each SART-TV iteration, backprojection is performed with a set of weighting factors that favor the desired respiratory phase. To reduce reconstruction time, the algorithm is implemented on a graphics processing unit. The performance of the proposed approach was investigated in simulations and in vivo scans of mice with primary lung cancers imaged with our in-house developed dual tube/detector micro-CT system. We note that if the ECG signal is acquired during sampling, the same approach could be used for phase-selective cardiac imaging.

  4. Image reconstruction from phased-array data based on multichannel blind deconvolution.

    Science.gov (United States)

    She, Huajun; Chen, Rong-Rong; Liang, Dong; Chang, Yuchou; Ying, Leslie

    2015-11-01

    In this paper we consider image reconstruction from fully sampled multichannel phased array MRI data without knowledge of the coil sensitivities. To overcome the non-uniformity of the conventional sum-of-square reconstruction, a new framework based on multichannel blind deconvolution (MBD) is developed for joint estimation of the image function and the sensitivity functions in image domain. The proposed approach addresses the non-uniqueness of the MBD problem by exploiting the smoothness of both functions in the image domain through regularization. Results using simulation, phantom and in vivo experiments demonstrate that the reconstructions by the proposed algorithm are more uniform than those by the existing methods. PMID:26119418

  5. A multi-phase level set framework for source reconstruction in bioluminescence tomography

    International Nuclear Information System (INIS)

    We propose a novel multi-phase level set algorithm for solving the inverse problem of bioluminescence tomography. The distribution of unknown interior source is considered as piecewise constant and represented by using multiple level set functions. The localization of interior bioluminescence source is implemented by tracing the evolution of level set function. An alternate search scheme is incorporated to ensure the global optimal of reconstruction. Both numerical and physical experiments are performed to evaluate the developed level set reconstruction method. Reconstruction results show that the proposed method can stably resolve the interior source of bioluminescence tomography.

  6. Theoretical study of ferroelectric nanoparticles using phase reconstructed electron microscopy

    DEFF Research Database (Denmark)

    Phatak, C.; Petford-Long, A. K.; Beleggia, Marco;

    2014-01-01

    Ferroelectric nanostructures are important for a variety of applications in electronic and electro-optical devices, including nonvolatile memories and thin-film capacitors. These applications involve stability and switching of polarization using external stimuli, such as electric fields. We present...... a theoretical model describing how the shape of a nanoparticle affects its polarization in the absence of screening charges, and quantify the electron-optical phase shift for detecting ferroelectric signals with phase-sensitive techniques in a transmission electron microscope. We provide an example...... phase shift computation for a uniformly polarized prolate ellipsoid with varying aspect ratio in the absence of screening charges....

  7. Bacterial Influence on the Solubility of Cinnabar and Metacinnabar at New Idria, CA

    Science.gov (United States)

    Jew, A. D.; Rytuba, J. J.; Spormann, A. M.; Brown, G. E.

    2007-12-01

    Mercury in the forms of cinnabar (α-HgS) and metacinnabar (β-HgS) is generally considered to be unreactive and of little environmental concern. To determine if this current belief is valid, a consortium of bacteria (including a Thiomonas intermedia-like bacterium) was taken from the acid mine drainage (AMD) pond at the New Idria Hg Mine, San Benito Co., CA, and inoculated into filter-sterilized AMD pond water (pH = 4) containing either ground cinnabar or metacinnabar crystals (Experiments conducted with (1) α- HgS or β-HgS in the presence of killed bacteria (anaerobic), (2) α-HgS with pond water (abiotic), and (3) β-HgS with AMD pond water (abiotic) showed drops in aqueous Hg to below the detection limit (0.1ng/L) within 12 days. Anaerobic growth of the bacterial consortium showed a pattern similar to those of the abiotic water-HgS experiments, except that Hg levels dropped below detection limit within 6 days. These combined results suggest that HgS degradation by this bacterial consortium is an aerobic process. Killed bacteria incubated aerobically showed a slight increase in Hg levels over background water levels (enzymes might be involved in the dissolution of HgS and were still viable for ~6 days after sterilization. In aerobic living incubations, the activities of different mercury and sulfide species were estimated using the thermodynamic modeling program Minteq with AMD pond water chemistry determined by ICP-MS and total mercury and total sulfide analyses. These calculations give an equilibrium solubility product for the dissolution of HgS up to 25 orders of magnitude higher than HgS under standard conditions. When compared to calculations by Paquette et al., 1997 and Benoit et al., 1999, the bacterial consortium at New Idria causes an increase in the pK for all reported reactions including H+, HS-, and H2S of 11-13 orders of magnitude. These results indicate that the biofilm consortium at the New Idria AMD pond has a profound effect on the solubility

  8. Phase space reconstruction of chaotic dynamical system based on wavelet decomposition

    International Nuclear Information System (INIS)

    In view of the disadvantages of the traditional phase space reconstruction method, this paper presents the method of phase space reconstruction based on the wavelet decomposition and indicates that the wavelet decomposition of chaotic dynamical system is essentially a projection of chaotic attractor on the axes of space opened by the wavelet filter vectors, which corresponds to the time-delayed embedding method of phase space reconstruction proposed by Packard and Takens. The experimental results show that, the structure of dynamical trajectory of chaotic system on the wavelet space is much similar to the original system, and the nonlinear invariants such as correlation dimension, Lyapunov exponent and Kolmogorov entropy are still reserved. It demonstrates that wavelet decomposition is effective for characterizing chaotic dynamical system. (general)

  9. Identify the Rotating Stall in Centrifugal Compressors by Fractal Dimension in Reconstructed Phase Space

    Directory of Open Access Journals (Sweden)

    Le Wang

    2015-11-01

    Full Text Available Based on phase space reconstruction and fractal dynamics in nonlinear dynamics, a method is proposed to extract and analyze the dynamics of the rotating stall in the impeller of centrifugal compressor, and some numerical examples are given to verify the results as well. First, the rotating stall of an existing low speed centrifugal compressor (LSCC is numerically simulated, and the time series of pressure in the rotating stall is obtained at various locations near the impeller outlet. Then, the phase space reconstruction is applied to these pressure time series, and a low-dimensional dynamical system, which the dynamics properties are included in, is reconstructed. In phase space reconstruction, C–C method is used to obtain the key parameters, such as time delay and the embedding dimension of the reconstructed phase space. Further, the fractal characteristics of the rotating stall are analyzed in detail, and the fractal dimensions are given for some examples to measure the complexity of the flow in the post-rotating stall. The results show that the fractal structures could reveal the intrinsic dynamics of the rotating stall flow and could be considered as a characteristic to identify the rotating stall.

  10. Phase-sensitive fluorescent imaging with coherent reconstruction

    CERN Document Server

    Field, Jeffrey J; Bartels, Randy A

    2015-01-01

    Optical imaging plays a critical role in advancing our understanding of three dimensional dynamics of biological systems. Coherent imaging (CI) methods exploit spatial phase information, encoded through propagation of coherent signal light emerging from a specimen, to extract a three-dimensional representation of the object from a single high-speed measurement. Until now, CI methods could not be applied to incoherent light, severely limiting their ability to image the most powerful biological probes available - fluorescent molecules - with sufficient speed and volume to observe important processes, such as neural processing in live specimens. We introduce a new imaging technique that transfers the spatial propagation phase of coherent illumination light to incoherent fluorescent light emission. The transfer of propagation phase allows CI techniques to be applied to fluorescent light imaging, and leads to large increases in imaging speed and depth of field. With this advance, biological imaging of fluorescent ...

  11. Exposure to Low Dose of Cinnabar (a Naturally Occurring Mercuric Sulfide (HgS Caused Neurotoxicological Effects in Offspring Mice

    Directory of Open Access Journals (Sweden)

    Chun-Fa Huang

    2012-01-01

    Full Text Available Cinnabar, a naturally occurring mercuric sulfide (HgS, has long been used in Chinese mineral medicine for more than 2000 years. Although mercury is well-known for its toxicity, whether cinnabar induces neurotoxicity, especially in infants and children, is unknown. The purpose of this study was to explore the neurotoxic effects of low-dose of cinnabar (10 mg/kg/day on developing mice. The results revealed neurobehavioral defects in F1-C-Cin group, which were associated with Hg accumulation, increased NOx levels in whole blood, and Na+/K+-ATPase activities in brain tissues. F1- and F2-Cin-V groups were found to increase brain Hg contents and prominent neurobehavioral defects compared with F1-C-V group, suggesting that the fetal brain was more susceptible to irreversible effects for cinnabar-induced damage. Moreover, F1- and F2-Cin-Cin groups had severely neurobehavioral dysfunctions, closely correlated with the further alteration of NOx levels and Na+/K+-ATPase activities than F1- and F2-C-Cin groups. Effects in F2-Cin-Cin group were more significant than those in F1-Cin-Cin group. In conclusion, this study demonstrates that exposure to low-dose of cinnabar during the perinatal and developmental stages results in irreversible and severe injuries of the neurotoxicity in offspring, and NOx and Na+/K+-ATPase activities may exist potential and useful biomarkers for neurotoxicity-induced by low-doses of mercuric compounds.

  12. Iodide retention by cinnabar (HgS) and chalcocite (Cu{sub 2}S)

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, H.L.; Balsley, S.D.; Brady, P.V.

    1995-07-01

    Sorption of iodide (I{sup {minus}}) on cinnabar (HgS) and chalcocite (Cu{sub 2}S) was examined as a function of pH at 25{degrees}C in a series of batch experiments. Calculated distribution ratios (K{sub d}) far exceed those reported for other minerals; maximal K{sub d}`s of 1375 cc/g (Cu{sub 2}S) and 3080 c/g (HgS) were observed between pH 4-5, but wre substantial at all pH`s measured (4 < pH < 10). Iodide sorption apparently occurs by the formation of an insoluble surface solid solution with exposed Hg and Cu sites. Surface solid solution formation is favored at low pH due to the lessened electrostatic repulsion of the iodide ion by the sulfide surfaces.

  13. High-contrast pattern reconstructions using a phase-seeded point CGH method.

    Science.gov (United States)

    McWilliam, Richard; Williams, Gavin L; Cowling, Joshua J; Seed, Nicholas L; Purvis, Alan

    2016-03-01

    A major challenge encountered in digital holography applications is the need to synthesize computer-generated holograms (CGHs) that are realizable as phase-only elements while also delivering high quality reconstruction. This trade-off is particularly acute in high-precision applications such as photolithography where contrast typically must exceed 0.6. A seeded-phase point method is proposed to address this challenge, whereby patterns composed of fine lines that intersect and form closed shapes are reconstructed with high contrast while maintaining a phase-only CGH. The method achieves superior contrast to that obtained by uniform or random seeded-phase methods while maintaining computational efficiency for large area exposures. It is also shown that binary phase modulation achieves similar contrast performance with benefits for the fabrication of simpler diffractive optical elements. PMID:26974633

  14. Joint reconstruction of absorption and refractive properties in propagation-based x-ray phase-contrast tomography via a non-linear image reconstruction algorithm

    Science.gov (United States)

    Chen, Yujia; Wang, Kun; Gursoy, Doga; Soriano, Carmen; De Carlo, Francesco; Anastasio, Mark A.

    2016-03-01

    Propagation-based X-ray phase-contrast tomography (XPCT) provides the opportunity to image weakly absorbing objects and is being explored actively for a variety of important pre-clinical applications. Quantitative XPCT image reconstruction methods typically involve a phase retrieval step followed by application of an image reconstruction algorithm. Most approaches to phase retrieval require either acquiring multiple images at different object-to-detector distances or introducing simplifying assumptions, such as a single-material assumption, to linearize the imaging model. In order to overcome these limitations, a non-linear image reconstruction method has been proposed previously that jointly estimates the absorption and refractive properties of an object from XPCT projection data acquired at a single propagation distance, without the need to linearize the imaging model. However, the numerical properties of the associated non-convex optimization problem remain largely unexplored. In this study, computer simulations are conducted to investigate the feasibility of the joint reconstruction problem in practice. We demonstrate that the joint reconstruction problem is ill-posed and sensitive to system inconsistencies. Particularly, the method can generate accurate refractive index images only if the object is thin and has no phase-wrapping in the data. However, we also observed that, for weakly absorbing objects, the refractive index images reconstructed by the joint reconstruction method are, in general, more accurate than those reconstructed using methods that simply ignore the object's absorption.

  15. Chemical ecology of the cinnabar moth ( Tyria jacobaeae ) on a newly recorded host Senecio adonidifolius

    Science.gov (United States)

    Vrieling, Klaas

    2006-09-01

    The cinnabar moth ( Tyria jacobaeae, Arctiidae) normally feeds on Senecio jacobaea in the field. For the first time, naturally occurring populations of T. jacobaeae have been found thriving on Senecio adonidifolius, even though the moth's preferred host, S. jacobaea, is available within 50-400 m. In the laboratory, the cinnabar moth has been shown to feed on and develop on S. adonidifolius despite its different leaf morphology, pyrrolizidine alkaloid (PA) profile and a large taxonomic distance to S. jacobaea. Here I examined whether T. jacobaeae has adapted to this new host in the field using adult oviposition behavior and plant acquired defense chemistry in pupae as criteria. Choice tests indicated local adaptation to this newly recorded host. T. jacobaeae reared on S. adonidifolius hosts laid more egg batches and total eggs on it than T. jacobaeae from S. jacobaea. The egg batches were smaller on S. adonidifolius possibly due to highly pinnate thread-like structure of its leaves. The bouquet of plant acquired PAs and the insect metabolized callimorphine in pupae differed widely between pupae collected from the two hosts. T. jacobaeae pupae taken from S. adonidifolius hosts contained more of the insect metabolized callimorphine than pupae taken from S. jacobaea hosts, but they did not differ in total PA concentration. Pupae taken from S. jacobaea hosts contained more unmetabolized plant PA's than pupae from S. adonidifolius hosts. Additionally, 10% of T. jacobaeae larvae taken from S. adonidifolius in Biausse were infested with Carcelia dubia, a parasitic and rare tachinid fly that typically attacks arctiid moths.

  16. Image reconstruction exploiting object sparsity in boundary-enhanced X-ray phase-contrast tomography.

    Science.gov (United States)

    Sidky, Emil Y; Anastasio, Mark A; Pan, Xiaochuan

    2010-05-10

    Propagation-based X-ray phase-contrast tomography (PCT) seeks to reconstruct information regarding the complex-valued refractive index distribution of an object. In many applications, a boundary-enhanced image is sought that reveals the locations of discontinuities in the real-valued component of the refractive index distribution. We investigate two iterative algorithms for few-view image reconstruction in boundary-enhanced PCT that exploit the fact that a boundary-enhanced PCT image, or its gradient, is often sparse. In order to exploit object sparseness, the reconstruction algorithms seek to minimize the l(1)-norm or TV-norm of the image, subject to data consistency constraints. We demonstrate that the algorithms can reconstruct accurate boundary-enhanced images from highly incomplete few-view projection data. PMID:20588896

  17. Computer vision tools to optimize reconstruction parameters in x-ray in-line phase tomography

    International Nuclear Information System (INIS)

    In this article, a set of three computer vision tools, including scale invariant feature transform (SIFT), a measure of focus, and a measure based on tractography are demonstrated to be useful in replacing the eye of the expert in the optimization of the reconstruction parameters in x-ray in-line phase tomography. We demonstrate how these computer vision tools can be used to inject priors on the shape and scale of the object to be reconstructed. This is illustrated with the Paganin single intensity image phase retrieval algorithm in heterogeneous soft tissues of biomedical interest, where the selection of the reconstruction parameters was previously made from visual inspection or physical assumptions on the composition of the sample. (paper)

  18. Evaluation of a new reconstruction algorithm for x-ray phase-contrast imaging

    Science.gov (United States)

    Seifert, Maria; Hauke, Christian; Horn, Florian; Lachner, Sebastian; Ludwig, Veronika; Pelzer, Georg; Rieger, Jens; Schuster, Max; Wandner, Johannes; Wolf, Andreas; Michel, Thilo; Anton, Gisela

    2016-04-01

    X-ray grating-based phase-contrast imaging might open up entirely new opportunities in medical imaging. However, transferring the interferometer technique from laboratory setups to conventional imaging systems the necessary rigidity of the system is difficult to achieve. Therefore, vibrations or distortions of the system lead to inaccuracies within the phase-stepping procedure. Given insufficient stability of the phase-step positions, up to now, artifacts in phase-contrast images occur, which lower the image quality. This is a problem with regard to the intended use of phase-contrast imaging in clinical routine as for example tiny structures of the human anatomy cannot be observed. In this contribution we evaluate an algorithm proposed by Vargas et.al.1 and applied to X-ray imaging by Pelzer et.al. that enables us to reconstruct a differential phase-contrast image without the knowledge of the specific phase-step positions. This method was tested in comparison to the standard reconstruction by Fourier analysis. The quality of phase-contrast images remains stable, even if the phase-step positions are completely unknown and not uniformly distributed. To also achieve attenuation and dark-field images the proposed algorithm has been combined with a further algorithm of Vargas et al.3 Using this algorithm, the phase-step positions can be reconstructed. With the help of the proper phase-step positions it is possible to get information about the phase, the amplitude and the offset of the measured data. We evaluated this algorithm concerning the measurement of thick objects which show a high absorbency.

  19. Diagnostic efficiency of Mueller-matrix polarization reconstruction system of the phase structure of liver tissue

    Science.gov (United States)

    Zabolotna, Natalia I.; Pavlov, Sergii V.; Radchenko, Kostiantyn O.; Stasenko, Vladyslav A.; Wójcik, Waldemar; Kussambayeva, Nazym

    2015-12-01

    The application field of using the Mueller-matrix polarizing reconstruction system of phase structure of biological layer for optical-anisotropic parameters differentiation of histological sections of healthy and rat's liver with hepatitis were investigated. Comparison of system informativity with known systems on indexes of sensitivity, specificity and balanced accuracy were performed.

  20. Simultaneous reconstruction of phase and amplitude contrast from a single holographic record

    CERN Document Server

    Latychevskaia, Tatiana

    2009-01-01

    We present a reconstruction technique for simultaneous retrieval of absorption and phase shifting properties of an object recorded by in-line holography. The routine is experimentally tested by applying it to optical holograms of a pure phase respectively amplitude object of micrometer dimensions that has been machined into a glass-plate using a focused ion beam. The method has also been applied to previously published electron holograms of single DNA molecules.

  1. FY 1991 project plan for the Hanford Environmental Dose Reconstruction Project, Phase 2

    International Nuclear Information System (INIS)

    Phase 1 of the Hanford Environmental Dose Reconstruction Project was designed to develop and demonstrate a method for estimating radiation doses people may have received from Hanford Site operations since 1944. The method researchers developed relied on a variety of measured and reconstructed data as input to a modular computer model that generates dose estimates and their uncertainties. As part of Phase 1, researchers used the reconstructed data and computer model to calculate preliminary dose estimates for populations in a limited geographical area and time period. Phase 2, now under way, is designed to evaluate the Phase 1 data and model and improve them to calculate more accurate and precise dose estimates. Phase 2 will also be used to obtain preliminary estimates of two categories of doses: for Native American tribes and for individuals included in the pilot phase of the Hanford Thyroid Disease Study (HTDS). TSP Directive 90-1 required HEDR staff to develop Phase 2 task plans for TSP approval. Draft task plans for Phase 2 were submitted to the TSP at the October 11--12, 1990 public meeting, and, after discussions of each activity and associated budget needs, the TSP directed HEDR staff to proceed with a slate of specific project activities for FY 1991 of Phase 2. This project plan contains detailed information about those activities. Phase 2 is expected to last 15--18 months. In mid-FY 1991, project activities and budget will be reevaluated to determine whether technical needs or priorities have changed. Separate from, but related to, this project plan, will be an integrated plan for the remainder of the project. HEDR staff will work with the TSP to map out a strategy that clearly describes ''end products'' for the project and the work necessary to complete them. This level of planning will provide a framework within which project decisions in Phases 2, 3, and 4 can be made

  2. Reconstruction of purely absorbing, absorbing and phase-shifting, and strong phase-shifting objects from their single-shot in-line holograms

    CERN Document Server

    Latychevskaia, Tatiana

    2015-01-01

    We address the problem of reconstructing phase-shifting objects from their single shot in-line holograms. We show that a phase-shifting object cannot be reliably recovered from its in-line hologram by conventional reconstruction routines but that an iterative reconstruction should be applied. We demonstrate examples of simulated in-line holograms of objects with the following properties: purely absorbing, both absorbing and phase shifting, and strong phase-shifting. We investigate the effects of noise and interference resolution in holograms on the reconstruction results and discuss details of an optimal iterative procedure to quantitatively recover the correct absorbing and phase-shifting properties of the object. We also review previously published reconstructions of experimental holograms and summarize the optimal parameters for retrieval of phase-shifting objects from their in-line holograms.

  3. An improved phase shift reconstruction algorithm of fringe scanning technique for X-ray microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Lian, S.; Yang, H., E-mail: yang.haiquan@gmail.com [Midorino Research Corporation, 5-15-13 Chuo Rinkan Nishi, Yamato, Kanagawa 242-0008 (Japan); Kudo, H. [Division of Information Engineering, Faculty of Engineering, Information and Systems, University of Tsukuba, 1-1-1 Tennoudai, Tsukuba, Ibaraki 305-8573 (Japan); Momose, A.; Yashiro, W. [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan)

    2015-02-15

    The X-ray phase imaging method has been applied to observe soft biological tissues, and it is possible to image the soft tissues by using the benefit of the so-called “Talbot effect” by an X-ray grating. One type of the X-ray phase imaging method was reported by combining an X-ray imaging microscope equipped by a Fresnel zone plate with a phase grating. Using the fringe scanning technique, a high-precision phase shift image could be obtained by displacing the grating step by step and measuring dozens of sample images. The number of the images was selected to reduce the error caused by the non-sinusoidal component of the Talbot self-image at the imaging plane. A larger number suppressed the error more but increased radiation exposure and required higher mechanical stability of equipment. In this paper, we analyze the approximation error of fringe scanning technique for the X-ray microscopy which uses just one grating and proposes an improved algorithm. We compute the approximation error by iteration and substitute that into the process of reconstruction of phase shift. This procedure will suppress the error even with few sample images. The results of simulation experiments show that the precision of phase shift image reconstructed by the proposed algorithm with 4 sample images is almost the same as that reconstructed by the conventional algorithm with 40 sample images. We also have succeeded in the experiment with real data.

  4. X-ray phase laminography with a grating interferometer using iterative reconstruction

    International Nuclear Information System (INIS)

    X-ray phase computed laminography is performed using a Talbot interferometer and synchrotron radiation. An iterative reconstruction algorithm which includes prior information about limited support, range of values and sparsity of the imaged object has been developped. It allows the reconstruction of objects with an improved resolution of the unsampled frequencies, compared to the classical filtered backprojection. The imaging method, demonstrated for a nylon mesh sample and a leaf sample, shows promising results for the imaging of flat, laterally extended objects made of low absorbing elements.

  5. X-ray phase laminography with a grating interferometer using iterative reconstruction

    Science.gov (United States)

    Harasse, Sébastien; Yashiro, Wataru; Momose, Atsushi

    2012-07-01

    X-ray phase computed laminography is performed using a Talbot interferometer and synchrotron radiation. An iterative reconstruction algorithm which includes prior information about limited support, range of values and sparsity of the imaged object has been developped. It allows the reconstruction of objects with an improved resolution of the unsampled frequencies, compared to the classical filtered backprojection. The imaging method, demonstrated for a nylon mesh sample and a leaf sample, shows promising results for the imaging of flat, laterally extended objects made of low absorbing elements.

  6. X-ray phase laminography with a grating interferometer using iterative reconstruction

    Energy Technology Data Exchange (ETDEWEB)

    Harasse, Sebastien; Yashiro, Wataru; Momose, Atsushi [Department of Advanced Materials Science, Graduate School of Frontier Sciences, University of Tokyo (Japan)

    2012-07-31

    X-ray phase computed laminography is performed using a Talbot interferometer and synchrotron radiation. An iterative reconstruction algorithm which includes prior information about limited support, range of values and sparsity of the imaged object has been developped. It allows the reconstruction of objects with an improved resolution of the unsampled frequencies, compared to the classical filtered backprojection. The imaging method, demonstrated for a nylon mesh sample and a leaf sample, shows promising results for the imaging of flat, laterally extended objects made of low absorbing elements.

  7. Accuracy enhancement of three-dimensional reconstruction using phase-shifting shadow moiré

    Science.gov (United States)

    Jamali Avilagh, Ali; Rezaie, Amir Hossein

    2013-04-01

    An iterative algorithm and a denoising method for accuracy enhancement of three-dimensional (3-D) reconstruction processes by shadow moiré is proposed. Using traditional shadow moiré for 3-D reconstruction leads to a nonuniform phase shift error. The proposed iterative algorithm eliminates this error by using three phase-shifted interferograms and obtains precise phase information. Moreover the proposed denoising method, which is based on undecimated wavelet transform, effectively eliminates noise and grating patterns while retaining useful information. The proposed phase shifting shadow moiré method is compared with the structured lighting method, which is a common method for 3-D reconstruction, and it is further compared with traditional shadow moiré. The methods are simulated in a 3ds-Max environment. The simulation results show that the proposed shadow moiré technique achieves greater accuracy in comparison with the traditional shadow moiré and structured lighting techniques and also it has higher accuracy than existing typical phase-shifting algorithms.

  8. Transverse Phase Space Reconstruction and Emittance Measurement of Intense Electron Beams using a Tomography Technique

    International Nuclear Information System (INIS)

    Tomography is the technique of reconstructing an image from its projections. It is widely used in the medical community to observe the interior of the human body by processing multiple x-ray images taken at different angles, A few pioneering researchers have adapted tomography to reconstruct detailed phase space maps of charged particle beams. Some questions arise regarding the limitations of tomography technique for space charge dominated beams. For instance is the linear space charge force a valid approximation? Does tomography equally reproduce phase space for complex, experimentally observed, initial particle distributions? Does tomography make any assumptions about the initial distribution? This study explores the use of accurate modeling with the particle-in-cell code WARP to address these questions, using a wide range of different initial distributions in the code. The study also includes a number of experimental results on tomographic phase space mapping performed on University of Maryland Electron Ring (UMER)

  9. Electron bunch profile reconstruction based on phase-constrained iterative algorithm

    Science.gov (United States)

    Bakkali Taheri, F.; Konoplev, I. V.; Doucas, G.; Baddoo, P.; Bartolini, R.; Cowley, J.; Hooker, S. M.

    2016-03-01

    The phase retrieval problem occurs in a number of areas in physics and is the subject of continuing investigation. The one-dimensional case, e.g., the reconstruction of the temporal profile of a charged particle bunch, is particularly challenging and important for particle accelerators. Accurate knowledge of the longitudinal (time) profile of the bunch is important in the context of linear colliders, wakefield accelerators and for the next generation of light sources, including x-ray SASE FELs. Frequently applied methods, e.g., minimal phase retrieval or other iterative algorithms, are reliable if the Blaschke phase contribution is negligible. This, however, is neither known a priori nor can it be assumed to apply to an arbitrary bunch profile. We present a novel approach which gives reproducible, most-probable and stable reconstructions for bunch profiles (both artificial and experimental) that would otherwise remain unresolved by the existing techniques.

  10. Gated cardiac scanning using limited-angle image reconstruction technique and information in the neighboring phases

    International Nuclear Information System (INIS)

    It is known that there are gaps in scan angle in gated cardiac scanning due to lack of synchronization between heart beat and CT machine rotation. The missing projections in these gaps result in artifacts in the reconstructed images. In a previous paper an iterative limited-angle reconstruction technique was employed to fill in the missing projections to remove the artifacts. It was found there that the root-mean-square errors of the limited-angle images were reduced to a level comparable to those of reconstructions using complete-angle information. In the present paper the results are further improved by using the scans of a neighboring portion of the cardiac cycle as a first estimate of the missing scans in the phase of interest when initializing the iterations. Such a modification provides a better starting point for the iterations

  11. 256-Slice coronary computed tomographic angiography in patients with atrial fibrillation: optimal reconstruction phase and image quality

    Energy Technology Data Exchange (ETDEWEB)

    Oda, Seitaro; Yuki, Hideaki; Kidoh, Masafumi; Utsunomiya, Daisuke; Nakaura, Takeshi; Namimoto, Tomohiro; Yamashita, Yasuyuki [Kumamoto University, Department of Diagnostic Radiology, Faculty of Life Sciences, Chuou-ku, Kumamoto (Japan); Honda, Keiichi; Yoshimura, Akira; Katahira, Kazuhiro [Kumamoto Chuo Hospital, Department of Diagnostic Radiology, Minami-ku, Kumamoto (Japan); Noda, Katsuo; Oshima, Shuichi [Kumamoto Chuo Hospital, Department of Cardiology, Minami-ku, Kumamoto (Japan)

    2016-01-15

    To assess the optimal reconstruction phase and the image quality of coronary computed tomographic angiography (CCTA) in patients with atrial fibrillation (AF). We performed CCTA in 60 patients with AF and 60 controls with sinus rhythm. The images were reconstructed in multiple phases in all parts of the cardiac cycle, and the optimal reconstruction phase with the fewest motion artefacts was identified. The coronary artery segments were visually evaluated to investigate their assessability. In 46 (76.7 %) patients, the optimal reconstruction phase was end-diastole, whereas in 6 (10.0 %) patients it was end-systole or mid-diastole, and in 2 (3.3 %) patients it was another cardiac phase. In 53 (88.3 %) of the controls, the optimal reconstruction phase was mid-diastole, whereas it was end-systole in 4 (6.7 %), and in 3 (5.0 %) it was another cardiac phase. There was a significant difference between patients with AF and the controls in the optimal phase (p < 0.01) but not in the visual image quality score (p = 0.06). The optimal reconstruction phase in most patients with AF was the end-diastolic phase. The end-systolic phase tended to be optimal in AF patients with higher average heart rates. (orig.)

  12. 256-Slice coronary computed tomographic angiography in patients with atrial fibrillation: optimal reconstruction phase and image quality

    International Nuclear Information System (INIS)

    To assess the optimal reconstruction phase and the image quality of coronary computed tomographic angiography (CCTA) in patients with atrial fibrillation (AF). We performed CCTA in 60 patients with AF and 60 controls with sinus rhythm. The images were reconstructed in multiple phases in all parts of the cardiac cycle, and the optimal reconstruction phase with the fewest motion artefacts was identified. The coronary artery segments were visually evaluated to investigate their assessability. In 46 (76.7 %) patients, the optimal reconstruction phase was end-diastole, whereas in 6 (10.0 %) patients it was end-systole or mid-diastole, and in 2 (3.3 %) patients it was another cardiac phase. In 53 (88.3 %) of the controls, the optimal reconstruction phase was mid-diastole, whereas it was end-systole in 4 (6.7 %), and in 3 (5.0 %) it was another cardiac phase. There was a significant difference between patients with AF and the controls in the optimal phase (p < 0.01) but not in the visual image quality score (p = 0.06). The optimal reconstruction phase in most patients with AF was the end-diastolic phase. The end-systolic phase tended to be optimal in AF patients with higher average heart rates. (orig.)

  13. Phase Response of Fine Frequency Grid Reconstruction of Sampling Oscilloscopes Based on the NTN Calibration

    Directory of Open Access Journals (Sweden)

    Zhang Yichi

    2011-01-01

    Full Text Available This study describes an algorithm for determining the fine phase response of equivalent sampling oscilloscopes of a linear time-invariant response function from its magnitude. The Nose-to-Nose (NTN calibration method can give the phase response of the equivalent sampling oscilloscopes, but the phase resolution can only achieve 250 MHz because the limit of the technology. In this study the fine phase response has been reconstructed. Although the truncation of the Kramers-Kronig transform using three basic functions may approximate gives rise to large errors in estimated phase, these errors may be approximated by using three basic functions. This result rests on data obtained by an NTN technique in combination with a swept-sine calibration procedure. The NTN technique yields magnitude and phase information over a broad bandwidth, yet has low frequency resolution. The swept-sine procedure returns only the magnitude of the oscilloscope response function, yet can be made at any frequency at which fundamental microwave power standards are available. As an example, we get the fine phase response of equivalent sampling oscilloscopes Agilent 86100 C from dc to 40 GHz; its frequency resolution achieves 1 MHz. In the process of this analysis, we observe that the true oscilloscope response function as measured by the NTN calibration is indistinguishable from the reconstructed phase response over a very large bandwidth. At last we analyze the phase uncertainty of the phase response, and the uncertainty analysis process is provided. The results show that the algorithm can be used to get the fine phase response of the equivalent sampling oscilloscopes.

  14. Mercury in soils and plants in an abandoned cinnabar mining area (SW Spain).

    Science.gov (United States)

    García-Sánchez, A; Murciego, A; Alvarez-Ayuso, E; Regina, I Santa; Rodríguez-González, M A

    2009-09-15

    An abandoned cinnabar mining area located in the South-West of Spain has been studied with the aim of assessing its mercury pollution level and enhancing the knowledge about the Hg soil/plant relationship. To do so, soils and plants were sampled near an inactive smelter and around two mining sites present in this area. Critical total Hg concentrations were found in the close environs of pollutant sources. These also show high levels of elemental Hg (up to 8 mg kg(-1)), but quite low exchangeable Hg contents (0.008-0.038 mg kg(-1)). Most plant specimens display in their aboveground tissues Hg concentrations comprised in the range 0.1-10 mg kg(-1), with a great proportion (50%) showing critical levels. Greater Hg contents were found in plant specimens growing in soils with higher elemental Hg concentrations. The plant species displaying the greatest Hg levels are either perennial species of small-medium size and/or showing medium-highly corrugated leaves, or annual plants of small size. Marrubium vulgare L., Bromus madritensis L. and Trifolium angustifolium L. are the plant species with the highest Hg contents (37.6, 12.7 and 9.0 mg kg(-1), respectively). Leaf specific surface seems an important feature in the atmospheric Hg uptake by plants. PMID:19345007

  15. Neural network forecasting model based on phase space re-construction in water yield of mine

    Institute of Scientific and Technical Information of China (English)

    LIU Wei-lin; DONG Zeng-chuan; CHEN Nan-xiang; CAO Lian-hai

    2007-01-01

    The neutral network forecasting model based on the phase space reconstruction was proposed. First, through reconstructing the phase space, the time series of single variable was done excursion and expanded into multi- dimension series which included the ergodic information and more rich information could be excavated. Then, on the basis of the embedding dimension of the time series, the structure form of neutral network was constructed, of which the node number in input layer was the embedding dimension of the time series minus 1, and the node number in output layers was 1. Finally, as an example,the model was applied for water yield of mine forecasting. The result shows that the model has good fitting accuracy and forecasting precision.

  16. Quantitative 3D refractive index decrement reconstruction using single-distance phase-contrast tomography data

    International Nuclear Information System (INIS)

    X-ray propagation-based phase-contrast imaging is an attractive phase-sensitive imaging technique that has found applications in many research fields. Here, we report the investigations of a method which can quantitatively reconstruct in 3D the refractive index decrement of a quasi-homogeneous object using single-distance phase-contrast tomography data. The method extends the Born-type approximation phase-retrieval algorithm, which is based on the phase-attenuation duality (ε = δ/β, with constant ε) and suitable for homogeneous objects, to tomography and we study its application to quasi-homogeneous objects. The noise performance and the phase-attenuation duality influences of the method are also investigated. In simulation, the method allows us to quantitatively reconstruct the 3D refractive index decrement for quasi-homogeneous and weakly absorbing samples and it performs well in the practical noise situation. Furthermore, it shows a substantial contrast increase and successfully distinguishes different materials in a quasi-homogeneous and weakly absorbing sample from experimental data, even with inappropriate ε value. (paper)

  17. Phase discrepancy induced from least squares wavefront reconstruction of wrapped phase measurements with high noise or large localized wavefront gradients

    Science.gov (United States)

    Steinbock, Michael J.; Hyde, Milo W.

    2012-10-01

    Adaptive optics is used in applications such as laser communication, remote sensing, and laser weapon systems to estimate and correct for atmospheric distortions of propagated light in real-time. Within an adaptive optics system, a reconstruction process interprets the raw wavefront sensor measurements and calculates an estimate for the unwrapped phase function to be sent through a control law and applied to a wavefront correction device. This research is focused on adaptive optics using a self-referencing interferometer wavefront sensor, which directly measures the wrapped wavefront phase. Therefore, its measurements must be reconstructed for use on a continuous facesheet deformable mirror. In testing and evaluating a novel class of branch-point- tolerant wavefront reconstructors based on the post-processing congruence operation technique, an increase in Strehl ratio compared to a traditional least squares reconstructor was noted even in non-scintillated fields. To investigate this further, this paper uses wave-optics simulations to eliminate many of the variables from a hardware adaptive optics system, so as to focus on the reconstruction techniques alone. The simulation results along with a discussion of the physical reasoning for this phenomenon are provided. For any applications using a self-referencing interferometer wavefront sensor with low signal levels or high localized wavefront gradients, understanding this phenomena is critical when applying a traditional least squares wavefront reconstructor.

  18. Solution of the inverse problem of images reconstruction by the X-ray phase contrast method

    International Nuclear Information System (INIS)

    In the approximation of geometrical optics of the wave theory of X-ray diffraction an inverse problem of reconstruction of an internal structure of objects on the base of data of X-ray phase contrast method with the crystal-analyzer, located in Bragg geometry is analytically solved. It is shown, that the approximation of geometrical optics is fair, if the characteristic sizes of object exceed radius of the first Fresnel zone and the extinction length

  19. Reconstruction of material losses by perimeter penalization and phase-field methods

    OpenAIRE

    Rondi, Luca

    2009-01-01

    We treat the inverse problem of determining material losses, such as cavities, in a conducting body, by performing electrostatic measurements at the boundary. We develop a numerical approach, based on variational methods, to reconstruct the unknown material loss by a single boundary measurement of current and voltage type. The method is based on the use of phase-field functions to model the material losses and on a perimeter-like penalization to regularize the otherwise ill-posed problem.We j...

  20. Effect of different image reconstruction algorithms on phase analysis of gated myocardial perfusion SPECT studies

    International Nuclear Information System (INIS)

    Objective: To evaluate the effect of various iterative reconstruction methods on phase analysis of gated myocardial perfusion imaging (MPI). Methods: Thirty consecutive patients scanned by the Philips CardioMD system were recruited into this study. The gated SPECT (GSPECT) data were reconstructed with filtered backprojection (FBP), maximum likelihood expectation maximization (MLEM), three-dimensional (3D) resolution recovery MLEM (AST), attenuation corrected (AC) MLEM, AC and 3D Monte Carlo scatter corrected (ACSC) MLEM methods. Parameters of left ventricular (LV) dyssynchrony (phase standard deviation and histogram bandwidth) were measured using the software SyncTool. Paired t-test was used to compare the differences of the LV dyssynchrony indices between FBP and MLEM, AC MLEM, ACSC MLEM, AST respectively. Results: The phase standard deviations of stress GSPECT MPI for FBP, MLEM, AC MLEM, ACSC MLEM, and AST were 11.6 degree, 10.9 degree, 11.2 degree, 11.6 degree, 11.4 degree respectively;while the histogram bandwidths were 35.7 degree, 34.3 degree, 35.1 degree, 36.9 degree, 35.1 degree respectively. The phase standard deviations of rest GSPECT MPI for FBP, MLEM, AC MLEM, ACSC MLEM and AST were 15.2 degree, 14.5 degree, 15.4 degree, 15.4 degree, 14.8 degree respectively; while the histogram bandwidths were 47.3 degree, 46.4 degree, 46.4 degree, 47.9 degree, 46.1 degree respectively. No statistical significance was observed between the FBP and various iterative reconstruction methods for both the stress and rest GSPECT MPI study (t:-1.179 to 1.554, P>0.05 for all). Conclusion: The standard FBP reconstruction method is accurate enough for the measurement of LV dyssynchrony indices using the widely used clinical software SyncTool. (authors)

  1. Application analysis of empirical mode decomposition and phase space reconstruction in dam time-varying characteristic

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    In view of some courses of the time-varying characteristics processing in the analysis of dam deformation,the paper proposes a new method to analyze the dam time-varying characteristic based on the empirical mode decomposition and phase space reconstruction theory.First of all,to reduce the influences on the traditional statistical model from human factors and assure the analysis accuracy,response variables of the time-varying characteristic are obtained by the way of the empirical mode decomposition;and then,a phase plane of those variables is reconstructed to investigate their processing rules.These methods have already been applied to an actual project and the results showed that data interpretation with the assists of empirical mode decomposition and phase space reconstruction is effective in analyzing the perturbations of response variables,explicit in reflecting the entire development process,and valid for obtaining the evolution rules of the time-varying characteristic.This methodology is a powerful technical support for people to further master the rules of dam operation.

  2. Statistical iterative reconstruction algorithm for X-ray phase-contrast CT

    OpenAIRE

    Dieter Hahn; Pierre Thibault; Andreas Fehringer; Martin Bech; Thomas Koehler; Franz Pfeiffer; Peter B Noël

    2015-01-01

    Grating-based phase-contrast computed tomography (PCCT) is a promising imaging tool on the horizon for pre-clinical and clinical applications. Until now PCCT has been plagued by strong artifacts when dense materials like bones are present. In this paper, we present a new statistical iterative reconstruction algorithm which overcomes this limitation. It makes use of the fact that an X-ray interferometer provides a conventional absorption as well as a dark-field signal in addition to the phase-...

  3. Multi-oriented windowed harmonic phase reconstruction for robust cardiac strain imaging.

    Science.gov (United States)

    Cordero-Grande, Lucilio; Royuela-del-Val, Javier; Sanz-Estébanez, Santiago; Martín-Fernández, Marcos; Alberola-López, Carlos

    2016-04-01

    The purpose of this paper is to develop a method for direct estimation of the cardiac strain tensor by extending the harmonic phase reconstruction on tagged magnetic resonance images to obtain more precise and robust measurements. The extension relies on the reconstruction of the local phase of the image by means of the windowed Fourier transform and the acquisition of an overdetermined set of stripe orientations in order to avoid the phase interferences from structures outside the myocardium and the instabilities arising from the application of a gradient operator. Results have shown that increasing the number of acquired orientations provides a significant improvement in the reproducibility of the strain measurements and that the acquisition of an extended set of orientations also improves the reproducibility when compared with acquiring repeated samples from a smaller set of orientations. Additionally, biases in local phase estimation when using the original harmonic phase formulation are greatly diminished by the one here proposed. The ideas here presented allow the design of new methods for motion sensitive magnetic resonance imaging, which could simultaneously improve the resolution, robustness and accuracy of motion estimates. PMID:26745763

  4. Phase reconstruction by a multilevel iteratively regularized Gauss–Newton method

    International Nuclear Information System (INIS)

    In this paper we consider the numerical solution of a phase retrieval problem for a compactly supported, linear spline f : R → C with the Fourier transform f-circumflex, where values of |f| and |f-circumflex| at finitely many equispaced nodes are given. The unknown phases of complex spline coefficients fulfil a well-structured system of nonlinear equations. Thus the phase reconstruction leads to a nonlinear inverse problem, which is solved by a multilevel strategy and iterative Tikhonov regularization. The multilevel strategy concentrates the main effort of the solution of the phase retrieval problem in the coarse, less expensive levels and provides convenient initial guesses at the next finer level. On each level, the corresponding nonlinear system is solved by an iteratively regularized Gauss–Newton method. The multilevel strategy is motivated by convergence results of IRGN. This method is applicable to a wide range of examples as shown in several numerical tests for noiseless and noisy data

  5. Reconstruction of Protein Networks Using Reverse-Phase Protein Array Data.

    Science.gov (United States)

    von der Heyde, Silvia; Sonntag, Johanna; Kramer, Frank; Bender, Christian; Korf, Ulrike; Beißbarth, Tim

    2016-01-01

    In this chapter, we describe an approach to reconstruct cellular signaling networks based on measurements of protein activation after different stimulation experiments. As experimental platform reverse-phase protein arrays (RPPA) are used. RPPA allow the measurement of proteins and phosphoproteins across many samples in parallel with minimal sample consumption using a panel of highly target protein-specific antibodies. Functional interactions of proteins are modeled using a Boolean network. We describe the Boolean network reconstruction approach ddepn (dynamic deterministic effects propagation networks), which uses time course data to derive protein interactions based on perturbation experiments. We explain how the method works, give a practical application example, and describe how the results can be interpreted. Furthermore prior knowledge on signaling pathways is essential for network reconstruction. Here we describe the use of our software rBiopaxParser to integrate prior knowledge on protein signaling available in public databases. All applied methods are freely available as open-source R software packages. We describe the preparation of RPPA data as well as all relevant programming steps to format the RPPA data, to infer the prior knowledge, and to reconstruct and analyze the protein signaling networks. PMID:26519181

  6. Importance of phase unwrapping for the reconstruction of microwave tomographic images.

    Science.gov (United States)

    Grzegorczyk, Tomasz M; Meaney, Paul M; Jeon, Soon Ik; Geimer, Shireen D; Paulsen, Keith D

    2011-01-01

    Microwave image reconstruction is typically based on a regularized least-square minimization of either the complex-valued field difference between recorded and modeled data or the logarithmic transformation of these field differences. Prior work has shown anecdotally that the latter outperforms the former in limited surveys of simulated and experimental phantom results. In this paper, we provide a theoretical explanation of these empirical findings by developing closed form solutions for the field and the inverted electromagnetic property parameters in one dimension which reveal the dependency of the estimated permittivity and conductivity on the absolute (unwrapped) phase of the measured signal at the receivers relative to the source transmission. The analysis predicts the poor performance of complex-valued field minimization as target size and/or frequency and electromagnetic contrast increase. Such poor performance is avoided by logarithmic transformation and preservation of absolute measured signal phase. Two-dimensional experiments based on both synthetic and clinical data are used to confirm these findings. Robustness of the logarithmic transformation to variation in the initial guess of the reconstructed target properties is also shown. The results are generalizable to three dimensions and indicate that the minimization form with logarithmic transformation offers image reconstruction performance characteristics that are much more desirable for medial microwave imaging applications relative to minimizing differences in complex-valued field quantities. PMID:21339877

  7. A New PWM Modifying Technique for Reconstructing Three-phase Currents from DC Bus Current

    Science.gov (United States)

    Aoyagi, Shigehisa; Iwaji, Yoshitaka; Tobari, Kazuaki; Sakamoto, Kiyoshi

    Vector control is used to drive a DC brushless motor and generally needs current information. DC bus current detection is often adopted as a low cost method for reconstructing three-phase currents. PWM modifying techniques increase the DC pulse duration, thereby enabling easy detection of the DC bus current. However, these techniques have two problems: reducing a noise frequency and making the reconstructed current waveforms distorted by current ripple. In the techniques, modification signals are added to the three-phase voltage commands; the sum of the signals over a single cycle is zero. The authors examined several PWM modifying techniques from the points of view of noise and current distortion performance. One of the techniques had a good noise performance, and the frequency component of the noise was the same as the carrier frequency (fc). However, the reconstructed current waveforms were distorted. The total harmonic distortion (THD) varied from 1.7% to 4.1%. Another technique had a very poor noise performance, and the frequency component on the noise was one-fourth of fc. The authors developed a new PWM modifying method called “Half Pulse Shift”, which achieves the optimum noise and current distortion performance. The frequency component of the new method was two-thirds of fc, and the current waveforms were not distorted; the THD in the simulations and experiments was 0.5%-1.4% and 3.4%-3.6%, respectively.

  8. Draft Air Pathway Report: Phase 1 of the Hanford Environmental Dose Reconstruction Project

    Energy Technology Data Exchange (ETDEWEB)

    1990-07-20

    This report summarizes the air pathway portion of the first phase of the Hanford Environmental Dose Reconstruction (HEDR) Project, conducted by Battelle staff at the Pacific Northwest Laboratory under the direction of an independent Technical Steering Panel. The HEDR Project is estimating historical radiation doses that could have been received by populations near the Department of Energy's Hanford Site, in southeastern Washington State. Phase 1 of the air-pathway dose reconstruction sought to determine whether dose estimates could be calculated for populations in the 10 counties nearest the Hanford Site from atmospheric releases of iodine-131 from the site from 1944--1947. Phase 1 demonstrated the following: HEDR-calculated source-term estimates of iodine-131 releases to the atmosphere were within 20% of previously published estimates; calculated vegetation concentrations of iodine-131 agree well with previously published measurements; the highest of the Phase 1 preliminary dose estimates to the thyroid are consistent with independent, previously published estimates of doses to maximally exposed individuals; and relatively crude, previously published measurements of thyroid burdens for Hanford workers are in the range of average burdens that the HEDR model estimated for similar reference individuals'' for the period 1944--1947. 4 refs., 10 figs., 9 tabs.

  9. Formation of cinnabar--estimation of favourable conditions in a proposed Swedish repository.

    Science.gov (United States)

    Svensson, Margareta; Düker, Anders; Allard, Bert

    2006-08-25

    A deep repository for permanent storage of mercury will be designed and built in Sweden. The preferred chemical state for mercury in such a repository would be the sulphide HgS (cinnabar), which is a highly insoluble and the dominating natural mercury mineral. The possible formation of HgS from HgO or Hg(0) by reaction with a sulphur source (S, FeS or FeS(2)) is discussed from thermodynamic considerations, and pe-pH-diagrams are constructed by using the computer code MEDUSA to illustrate under which conditions HgS would dominate. Calculations of the speciation (PHREEQE) under varying conditions (S/Hg-ratios, presence of chloride) are given. Long-term laboratory experiments are performed, where the formation of HgS from the basic components is demonstrated (after mixing under various conditions and storage at room temperature for up to 3 years). The feasibility of HgS-formation with time in a geologic repository under conditions representative of deep granitic bedrock (calcium-bicarbonate buffered to pH 7-8.5) is discussed, as well as effects of alkaline conditions (concrete environment, pH 10.5-12.5). Formation of soluble polysulphides is not expected as long as the S/Hg mole ratio is within 1-1.3 and pH is below 10.5-11. Concrete should be used with caution. Suitable ballast materials could be introduced that would reduce porewater-pH that otherwise would be above 12. PMID:16504396

  10. Enhanced wavefront reconstruction by random phase modulation with a phase diffuser

    DEFF Research Database (Denmark)

    Almoro, Percival F; Pedrini, Giancarlo; Gundu, Phanindra Narayan;

    2011-01-01

    propagation in free space. The presentation of this technique is carried out using two setups. In the first setup, a diffuser plate is placed at the image plane of a metallic test object. The benefit of randomizing the phase of the object wave is the enhanced intensity recording due to high dynamic range of...... the diffusely scattered beam. The use of demagnification optics will also allow the investigations of relatively large objects. In the second setup, a transparent object is illuminated using a wavefront with random phase and constant amplitude by positioning the phase diffuser close to the object. The...

  11. Phasing of the Triatoma virus diffraction data using a cryo-electron microscopy reconstruction

    International Nuclear Information System (INIS)

    The blood-sucking reduviid bug Triatoma infestans, one of the most important vector of American human trypanosomiasis (Chagas disease) is infected by the Triatoma virus (TrV). TrV has been classified as a member of the Cripavirus genus (type cricket paralysis virus) in the Dicistroviridae family. This work presents the three-dimensional cryo-electron microscopy (cryo-EM) reconstruction of the TrV capsid at about 25 A resolution and its use as a template for phasing the available crystallographic data by the molecular replacement method. The main structural differences between the cryo-EM reconstruction of TrV and other two viruses, one from the same family, the cricket paralysis virus (CrPV) and the human rhinovirus 16 from the Picornaviridae family are presented and discussed

  12. Reconstructing source-sink dynamics in a population with a pelagic dispersal phase.

    Directory of Open Access Journals (Sweden)

    Kun Chen

    Full Text Available For many organisms, the reconstruction of source-sink dynamics is hampered by limited knowledge of the spatial assemblage of either the source or sink components or lack of information on the strength of the linkage for any source-sink pair. In the case of marine species with a pelagic dispersal phase, these problems may be mitigated through the use of particle drift simulations based on an ocean circulation model. However, when simulated particle trajectories do not intersect sampling sites, the corroboration of model drift simulations with field data is hampered. Here, we apply a new statistical approach for reconstructing source-sink dynamics that overcomes the aforementioned problems. Our research is motivated by the need for understanding observed changes in jellyfish distributions in the eastern Bering Sea since 1990. By contrasting the source-sink dynamics reconstructed with data from the pre-1990 period with that from the post-1990 period, it appears that changes in jellyfish distribution resulted from the combined effects of higher jellyfish productivity and longer dispersal of jellyfish resulting from a shift in the ocean circulation starting in 1991. A sensitivity analysis suggests that the source-sink reconstruction is robust to typical systematic and random errors in the ocean circulation model driving the particle drift simulations. The jellyfish analysis illustrates that new insights can be gained by studying structural changes in source-sink dynamics. The proposed approach is applicable for the spatial source-sink reconstruction of other species and even abiotic processes, such as sediment transport.

  13. Robust Compressive Phase Retrieval via L1 Minimization With Application to Image Reconstruction

    CERN Document Server

    Yang, Zai; Xie, Lihua

    2013-01-01

    Phase retrieval refers to a classical nonconvex problem of recovering a signal from its Fourier magnitude measurements. Inspired by the compressed sensing technique, signal sparsity is exploited in recent studies of phase retrieval to reduce the required number of measurements, known as compressive phase retrieval (CPR). In this paper, l1 minimization problems are formulated for CPR to exploit the signal sparsity and alternating direction algorithms are presented for problem solving. For real-valued, nonnegative image reconstruction, the image of interest is shown to be an optimal solution of the formulated l1 minimization in the noise free case. Numerical simulations demonstrate that the proposed approach is fast, accurate and robust to measurements noises.

  14. Optimization of reconstructed quality of hard x-ray phase microtomography.

    Science.gov (United States)

    Liu, Huiqiang; Wu, Xizeng; Xiao, Tiqiao

    2015-06-20

    For applications of hard x-ray propagation-based phase-contrast computed microtomography (PPCT) in high-resolution biological research, high spatial resolution and high contrast-to-noise ratio are simultaneously required for tiny structural discrimination and characterization. Most existing micro-CT techniques to improve image quality are limited by high cost, physical limitations, and complexity of the experimental hardware and setup. In this work, a novel PPCT technique, which combines a wavelet-transform-based modulation transform function compensation algorithm and a generalized phase-retrieval algorithm, is proposed to optimize the reconstruction quality of tomographic slices. Our experimental results, which compared the spatial resolutions and contrast-to-noise ratios of reconstructed images, demonstrated the validity of the proposed generalized PPCT technique. The experimental results showed that the proposed generalized PPCT technique is superior to the direct PPCT and the linearized phase-retrieval PPCT techniques. This novel PPCT technique demonstrates great potential for biological imaging, especially for applications that require high spatial resolution and limit radiation exposure. PMID:26193002

  15. Columbia River pathway report: phase I of the Hanford Environmental Dose Reconstruction Project

    Energy Technology Data Exchange (ETDEWEB)

    1991-07-01

    This report summarizes the river-pathway portion of the first phase of the Hanford Environmental Dose Reconstruction (HEDR) Project. The HEDR Project is estimating radiation doses that could have been received by the public from the Department of Energy's Hanford Site, in southeastern Washington State. Phase 1 of the river-pathway dose reconstruction effort sought to determine whether dose estimates could be calculated for populations in the area from above the Hanford Site at Priest Rapids Dam to below the site at McNary Dam from January 1964 to December 1966. Of the potential sources of radionuclides from the river, fish consumption was the most important. Doses from drinking water were lower at Pasco than at Richland and lower at Kennewick than at Pasco. The median values of preliminary dose estimates calculated by HEDR are similar to independent, previously published estimates of average doses to Richland residents. Later phases of the HEDR Project will address dose estimates for periods other than 1964--1966 and for populations downstream of McNary Dam. 17 refs., 19 figs., 1 tab.

  16. Mid- and long-term runoff predictions by an improved phase-space reconstruction model.

    Science.gov (United States)

    Hong, Mei; Wang, Dong; Wang, Yuankun; Zeng, Xiankui; Ge, Shanshan; Yan, Hengqian; Singh, Vijay P

    2016-07-01

    In recent years, the phase-space reconstruction method has usually been used for mid- and long-term runoff predictions. However, the traditional phase-space reconstruction method is still needs to be improved. Using the genetic algorithm to improve the phase-space reconstruction method, a new nonlinear model of monthly runoff is constructed. The new model does not rely heavily on embedding dimensions. Recognizing that the rainfall-runoff process is complex, affected by a number of factors, more variables (e.g. temperature and rainfall) are incorporated in the model. In order to detect the possible presence of chaos in the runoff dynamics, chaotic characteristics of the model are also analyzed, which shows the model can represent the nonlinear and chaotic characteristics of the runoff. The model is tested for its forecasting performance in four types of experiments using data from six hydrological stations on the Yellow River and the Yangtze River. Results show that the medium-and long-term runoff is satisfactorily forecasted at the hydrological stations. Not only is the forecasting trend accurate, but also the mean absolute percentage error is no more than 15%. Moreover, the forecast results of wet years and dry years are both good, which means that the improved model can overcome the traditional ''wet years and dry years predictability barrier,'' to some extent. The model forecasts for different regions are all good, showing the universality of the approach. Compared with selected conceptual and empirical methods, the model exhibits greater reliability and stability in the long-term runoff prediction. Our study provides a new thinking for research on the association between the monthly runoff and other hydrological factors, and also provides a new method for the prediction of the monthly runoff. PMID:26632992

  17. A novel approach for the diagnosis of ventricular tachycardia based on phase space reconstruction of ECG

    CERN Document Server

    Koulaouzidis, George; Cappiello, Grazia; Mazomenos, Evangelos B; Maharatna, Koushik; Morgan, John

    2014-01-01

    Ventricular arrhythmias comprise a group of disorders which manifest clinically in a variety of ways from ventricular premature beats (VPB) and no sustained ventricular tachycardia (in healthy subjects) to sudden cardiac death due to ventricular tachyarrhythmia in patients with and/or without structural heart disease. Ventricular fibrillation (VF) and ventricular tachycardia (VT) are the most common electrical mechanisms for cardiac arrest. Accurate and automatic recognition of these arrhythmias from electrocardiography (ECG) is a crucial task for medical professionals. The purpose of this research is to develop a new index for the differential diagnosis of normal sinus rhythm (SR) and ventricular arrhythmias, based on phase space reconstruction (PSR).

  18. Step effects on diffusion near a substrate reconstructive phase transition: H on W(100)

    OpenAIRE

    CAI Lei; Zheng, Chaozhi; Man, K. L.; Altman, M. S.; Granato, E.; Ala-Nissilä, Tapio; Ying, S. C.; Xiao, Xudong

    2003-01-01

    We have used the linear optical diffraction method to study the diffusion of hydrogen atoms on flat and stepped W(100) surfaces. At 0.17-monolayer (ML) H coverage, the diffusion coefficient (D) shows a strong anomalous dip at the substrate reconstructive phase transition temperature in an Arrhenius plot for diffusion on both surfaces. No anomalous diffusion behavior is observed at 1.2-ML H coverage on both surfaces in the entire range studied, 240–380 K, consistent with the absence of the pha...

  19. Blob population dynamics during immiscible two-phase flows in reconstructed porous media

    Science.gov (United States)

    Yiotis, A. G.; Talon, L.; Salin, D.

    2013-03-01

    We study the dynamics of nonwetting liquid blobs during immiscible two-phase flows in stochastically reconstructed porous domains predominantly saturated by a wetting fluid. The flow problem is solved explicitly using a Lattice-Boltzmann model that captures both the bulk phase and interfacial dynamics of the process. We show that the nonwetting blobs undergo a continuous life cycle of dynamic breaking up and coalescence producing two populations of blobs, a mobile and a stranded one, that exchange continuously mass between them. The process reaches a “steady state” when the rates of coalescence and breaking up become equal, and the macroscopic flow variables remain practically constant with time. At steady state, mass partitioning between mobile and immobile populations depends strongly on the applied Bond number Bo and the initial nonwetting phase distributions. Three flow regimes are identified: a single-phase flow Darcy-type regime at low Bo numbers, a non-Darcy two-phase flow regime at intermediate values of Bo, where the capillary number scales as Ca∝Bo2, and a Darcy-type two-phase flow regime at higher values of Bo. Our numerical results are found to be in good agreement with recent experimental and theoretical works.

  20. Phase-sensitive optical pulse characterization on a chip via Spectral Phase Interferometry for Direct Electric-Field Reconstruction (SPIDER)

    CERN Document Server

    Pasquazi, Alessia; Park, Yongwoo; Little, Brent E; Chu, Sai T; Morandotti, Roberto; Azana, Jose; Moss, David J

    2014-01-01

    The recent introduction of coherent optical communications has created a compelling need for ultra-fast phase-sensitive measurement techniques operating at milliwatt peak power levels and in time scales ranging from sub-picoseconds to nanoseconds. Previous reports of ultrafast optical signal measurements in integrated platforms[8-10] include time-lens temporal imaging on a silicon chip[8,9] and waveguide-based Frequency-Resolved Optical Gating (FROG). Time-lens imaging is phase insensitive while waveguide-based FROG methods require the integration of long tuneable delay lines - still an unsolved challenge. Here, we report a device capable of characterizing both the amplitude and phase of ultrafast optical pulses with the aid of a synchronized incoherently-related clock pulse. It is based on a novel variation of Spectral Phase Interferometry for Direct Electric-Field Reconstruction (SPIDER)that exploits degenerate four-wave-mixing (FWM) in a CMOS compatible chip. We measure pulses with 1THz, and up to 100ps pu...

  1. Laser Raman and resonance Raman spectroscopies of natural semiconductor mineral cinnabar, α-HgS, from various mines

    International Nuclear Information System (INIS)

    Natural minerals α-HgS from various mines have been studied by laser Raman spectroscopy and resonance Raman spectroscopy. The crystals differ from each other in the content of selenium impurity, included in samples from some mines. Based on the Raman spectra and the factor-group analysis the classification of the first order phonons and then the comparison of the results with the results from other works were carried out. The Raman spectra analysis of minerals from various mines show the selenium impurity gap vibration at 203 cm-1 and 226 cm-1 frequencies, respectively. On the basis of statistical measurements of the Raman spectra one can conclude that impurity frequencies of α-HgS may be generally used for the identification of the mine. Resonance Raman scattering for pure minerals has been studied by a dye laser. Phonon resonance in the indirect semiconductor α-HgS is found to be far more intense than the indirect resonance detected until now in various semiconductors in the proximity of the first indirect band Eg, for instance, in GaP. In our opinion, this may be conditioned by cinnabar band structure peculiarities. Low resonance has also been fixed in 'dirty' minerals at the spectral band frequency of 203 cm-1 characterizing gap vibration of isomorphic impurity Se in cinnabar

  2. An efficient reconstruction algorithm for differential phase-contrast tomographic images from a limited number of views

    International Nuclear Information System (INIS)

    The main focus of this paper is reconstruction of tomographic phase-contrast image from a set of projections. We propose an efficient reconstruction algorithm for differential phase-contrast computed tomography that can considerably reduce the number of projections required for reconstruction. The key result underlying this research is a projection theorem that states that the second derivative of the projection set is linearly related to the Laplacian of the tomographic image. The proposed algorithm first reconstructs the Laplacian image of the phase-shift distribution from the second-derivative of the projections using total variation regularization. The second step is to obtain the phase-shift distribution by solving a Poisson equation whose source is the Laplacian image previously reconstructed under the Dirichlet condition. We demonstrate the efficacy of this algorithm using both synthetically generated simulation data and projection data acquired experimentally at a synchrotron. The experimental phase data were acquired from a human coronary artery specimen using dark-field-imaging optics pioneered by our group. Our results demonstrate that the proposed algorithm can reduce the number of projections to approximately 33% as compared with the conventional filtered backprojection method, without any detrimental effect on the image quality

  3. An efficient reconstruction algorithm for differential phase-contrast tomographic images from a limited number of views

    Energy Technology Data Exchange (ETDEWEB)

    Sunaguchi, Naoki [Faculty of Science and Technology, Gunma University, Kiryu, Gunma 376-8515 (Japan); Yuasa, Tetsuya [Graduate School of Engineering and Science, Yamagata University, Yonezawa, Yamagata 992-8510 (Japan); Gupta, Rajiv [Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114 (United States); Ando, Masami [Research Institute for Science and Technology, Tokyo University of Science, Noda, Chiba 278-8510 (Japan)

    2015-12-21

    The main focus of this paper is reconstruction of tomographic phase-contrast image from a set of projections. We propose an efficient reconstruction algorithm for differential phase-contrast computed tomography that can considerably reduce the number of projections required for reconstruction. The key result underlying this research is a projection theorem that states that the second derivative of the projection set is linearly related to the Laplacian of the tomographic image. The proposed algorithm first reconstructs the Laplacian image of the phase-shift distribution from the second-derivative of the projections using total variation regularization. The second step is to obtain the phase-shift distribution by solving a Poisson equation whose source is the Laplacian image previously reconstructed under the Dirichlet condition. We demonstrate the efficacy of this algorithm using both synthetically generated simulation data and projection data acquired experimentally at a synchrotron. The experimental phase data were acquired from a human coronary artery specimen using dark-field-imaging optics pioneered by our group. Our results demonstrate that the proposed algorithm can reduce the number of projections to approximately 33% as compared with the conventional filtered backprojection method, without any detrimental effect on the image quality.

  4. Reconstructive Phase Transition in Ultrashort Peptide Nanostructures and Induced Visible Photoluminescence.

    Science.gov (United States)

    Handelman, Amir; Kuritz, Natalia; Natan, Amir; Rosenman, Gil

    2016-03-29

    A reconstructive phase transition has been found and studied in ultrashort di- and tripeptide nanostructures, self-assembled from biomolecules of different compositions and origin such as aromatic, aliphatic, linear, and cyclic (linear FF-diphenylalanine, linear LL-dileucine, FFF-triphenylalanine, and cyclic FF-diphenylalanine). The native linear aromatic FF, FFF and aliphatic LL peptide nanoensembles of various shapes (nanotubes and nanospheres) have asymmetric elementary structure and demonstrate nonlinear optical and piezoelectric effects. At elevated temperature, 140-180 °C, these native supramolecular structures (except for native Cyc-FF nanofibers) undergo an irreversible thermally induced transformation via reassembling into a completely new thermodynamically stable phase having nanowire morphology similar to those of amyloid fibrils. This reconstruction process is followed by deep and similar modification at all levels: macroscopic (morphology), molecular, peptide secondary, and electronic structures. However, original Cyc-FF nanofibers preserve their native physical properties. The self-fabricated supramolecular fibrillar ensembles exhibit the FTIR and CD signatures of new antiparallel β-sheet secondary folding with intermolecular hydrogen bonds and centrosymmetric structure. In this phase, the β-sheet nanofibers, irrespective of their native biomolecular origin, do not reveal nonlinear optical and piezoelectric effects, but do exhibit similar profound modification of optoelectronic properties followed by the appearance of visible (blue and green) photoluminescence (PL), which is not observed in the original peptides and their native nanostructures. The observed visible PL effect, ascribed to hydrogen bonds of thermally induced β-sheet secondary structures, has the same physical origin as that of the fluorescence found recently in amyloid fibrils and can be considered to be an optical signature of β-sheet structures in both biological and bioinspired

  5. Optimal image reconstruction phase at low and high heart rates in dual-source CT coronary angiography

    OpenAIRE

    Araoz, Philip A; Kirsch, Jacobo; Primak, Andrew N.; Braun, Natalie N.; Saba, Osama; Williamson, Eric E.; Harmsen, W. Scott; Mandrekar, Jayawant N.; McCollough, Cynthia H.

    2009-01-01

    The purpose of this study was to determine the cardiac phase having the highest coronary sharpness for low and high heart rate patients scanned with dual source CT (DSCT) and to compare coronary image sharpness over different cardiac phases. DSCT coronary CT scans for 30 low heart rate (≤ 70 beats per minute- bpm) and 30 high heart rate (>70 bpm) patients were reconstructed into different cardiac phases, starting at 30% and increasing at 5% increments until 70%. A blinded observer graded imag...

  6. Fully automated, high speed, tomographic phase object reconstruction using the transport of intensity equation in transmission and reflection configurations.

    Science.gov (United States)

    Nguyen, Thanh; Nehmetallah, George; Tran, Dat; Darudi, Ahmad; Soltani, Peyman

    2015-12-10

    While traditional transport of intensity equation (TIE) based phase retrieval of a phase object is performed through axial translation of the CCD, in this work a tunable lens TIE is employed in both transmission and reflection configurations. These configurations are extended to a 360° tomographic 3D reconstruction through multiple illuminations from different angles by a custom fabricated rotating assembly of the phase object. Synchronization circuitry is developed to control the CCD camera and the Arduino board, which in its turn controls the tunable lens and the stepper motor to automate the tomographic reconstruction process. Finally, a MATLAB based user friendly graphical user interface is developed to control the whole system and perform tomographic reconstruction using both multiplicative and inverse radon based techniques. PMID:26836869

  7. Cosmic flows and the expansion of the Local Universe from nonlinear phase-space reconstructions

    CERN Document Server

    Hess, Steffen

    2014-01-01

    We investigate the impact of cosmic flows and density perturbations on Hubble constant $H_0$ measurements using nonlinear phase-space reconstructions of the Local Universe (LU). We rely on a set of 25 N-body simulations which are constrained to resemble the LU within distances of about 90 Mpc/h. These have been randomly extended up to volumes enclosing distances of 360 Mpc/h with augmented Lagrangian perturbation theory (=750 simulations), accounting in this way for effects from from larger scales ($\\sigma_{\\rm large}=134$ km/s). We report on Local Group (LG) speed reconstructions, which are compatible with those derived from the CMB-dipole: $|v_{\\rm LG}|=685\\pm137$ km/s. The direction $(l,b)=(260.5\\pm 13.3,39.1\\pm 10.4)^\\circ$ is found to be compatible with observations. We use the CMB-dipole information to estimate the missing large scale bulk flow component, indicating that we miss a closely perpendicular flow with a magnitude corresponding to $1.4 \\sigma_{\\rm large}$. Considering this, our bulk flow estim...

  8. Online monitoring of gas-solid two-phase flow using projected CG method in ECT image reconstruction

    Institute of Scientific and Technical Information of China (English)

    Qi wang; Chengyi Yang; Huaxiang Wang; Ziqiang Cui; Zhentao Gao

    2013-01-01

    Electrical capacitance tomography (ECT) is a promising technique for multi-phase flow measurement due to its high speed,low cost and non-intrusive sensing.Image reconstruction for ECT is an inverse problem of finding the permittivity distribution of an object by measuring the electrical capacitances between sets of electrodes placed around its periphery.The conjugate gradient (CG) method is a popular image reconstruction method for ECT,in spite of its low convergence rate.In this paper,an advanced version of the CG method,the projected CG method,is used for image reconstruction of an ECT system.The solution space is projected into the Krylov subspace and the inverse problem is solved by the CG method in a low-dimensional specific subspace.Both static and dynamic experiments were carried out for gas-solid two-phase flows.The flow regimes are identified using the reconstructed images obtained with the projected CG method.The results obtained indicate that the projected CG method improves the quality of reconstructed images and dramatically reduces computation time,as compared to the traditional sensitivity,Landweber,and CG methods.Furthermore,the projected CG method was also used to estimate the important parameters of the pneumatic conveying process,such as the volume concentration,flow velocity and mass flow rate of the solid phase.Therefore,the projected CG method is considered suitable for online gas-solid two-phase flow measurement.

  9. Reconstruction of Sound Source Pressures in an Enclosure Using the Phased Beam Tracing Method

    DEFF Research Database (Denmark)

    Jeong, Cheol-Ho; Ih, Jeong-Guon

    2009-01-01

    Source identification in an enclosure is not an easy task due to complicated wave interference and wall reflections, in particular, at mid-high frequencies. In this study, a phased beam tracing method was applied to the reconstruction of source pressures inside an enclosure at medium frequencies...... all the pressure histories at the field points, source-observer relations can be constructed in a matrix-vector form for each frequency. By multiplying the measured field data with the pseudo-inverse of the calculated transfer function, one obtains the distribution of source pressure. An omni....... First, surfaces of an extended source are divided into reasonably small segments. From each source segment, one beam is projected into the field and all emitted beams are traced. Radiated beams from the source reach array sensors after traveling various paths including the wall reflections. Collecting...

  10. Sampling and Reconstruction of the Pupil and Electric Field for Phase Retrieval

    Science.gov (United States)

    Dean, Bruce; Smith, Jeffrey; Aronstein, David

    2012-01-01

    This technology is based on sampling considerations for a band-limited function, which has application to optical estimation generally, and to phase retrieval specifically. The analysis begins with the observation that the Fourier transform of an optical aperture function (pupil) can be implemented with minimal aliasing for Q values down to Q = 1. The sampling ratio, Q, is defined as the ratio of the sampling frequency to the band-limited cut-off frequency. The analytical results are given using a 1-d aperture function, and with the electric field defined by the band-limited sinc(x) function. Perfect reconstruction of the Fourier transform (electric field) is derived using the Whittaker-Shannon sampling theorem for 1field with no aliasing, which has been extended to 2-d optical apertures.

  11. Numerical Simulation of Two Phase Flow in Reconstructed Pore Network Based on Lattice Boltzmann Method

    Directory of Open Access Journals (Sweden)

    Song Rui

    2013-01-01

    Full Text Available Accurate prediction and understanding of the disorder microstructures in the porous media contribute to acquiring the macroscopic physical properties such as conductivity, permeability, formation factor, elastic moduli etc. Based on the rock serial sectioning images of Berea sandstone acquired by the core scanning system developed by our research group, the reconstructed rock model is established in the Mimics software and the extracted pore network of the porous rock is accomplished by the self-programming software in C++ programming language based on the revised Medial axis based algorithm and the Maximal ball algorithm. Using a lattice Boltzmann method, the single and two C phase flow are accomplished. Both of the pore-scale networks and the seepage mechanism of the single- and two Cphase flow are identical with the benchmark experimental data.

  12. Phase reconstruction of strong-field excited systems by transient-absorption spectroscopy

    CERN Document Server

    Liu, Z; Ott, C; Meyer, K; Mi, Y; Harman, Z; Keitel, C H; Pfeifer, T

    2015-01-01

    We study the evolution of a V-type three-level system, whose two resonances are coherently excited and coupled by two ultrashort laser pump and probe pulses, separated by a varying time delay. We relate the quantum dynamics of the excited multi-level system to the absorption spectrum of the transmitted probe pulse. In particular, by analyzing the quantum evolution of the system, we interpret how atomic phases are differently encoded in the time-delay-dependent spectral absorption profiles when the pump pulse either precedes or follows the probe pulse. We experimentally apply this scheme to atomic Rb, whose fine-structure-split $5s\\,^2S_{1/2}\\rightarrow 5p\\,^2P_{1/2}$ and $5s\\,^2S_{1/2}\\rightarrow 5p\\,^2P_{3/2}$ transitions are driven by the combined action of a pump pulse of variable intensity and a delayed probe pulse. The provided understanding of the relationship between quantum phases and absorption spectra represents an important step towards full time-dependent phase reconstruction (quantum holography) ...

  13. Air pathway report: Phase I of the Hanford Environmental Dose Reconstruction Project

    Energy Technology Data Exchange (ETDEWEB)

    1991-07-01

    Phase 1 of the air-pathway portion of the Hanford Environmental Dose Reconstruction (HEDR) Project sought to determine whether dose estimates could be calculated for populations in the 10 counties nearest the Hanford Site from atmospheric releases of iodine-131 from the site from 1944--1947. Phase 1 demonstrated the following: HEDR-calculated source-term estimates of iodine-131 releases to the atmosphere were within 20% of previously published estimates; calculated vegetation concentrations of iodine-131 agree well with previously published measurements; the highest of the Phase 1 preliminary dose estimates to the thyroid are consistent with independent, previously published estimates of doses to maximally exposed individuals; and, relatively crude, previously published measurements of thyroid burdens for Hanford workers are in the range of average burdens that the HEDR model estimated for similar reference individuals'' for the period 1944--1947. Preliminary median dose estimates summed over the year 1945--1947 for the primary pathway, air-pasture-cow-milk-thyroid, ranged from low median values of 0.006 rad for upwind adults who obtained milk from backyard cows not on pasture to high median values of 68.0 rad for downwind infants who drank milk from pasture-fed cows. Extremes of the estimated range are a low of essentially zero to upwind adults and a high of almost 3000 rem to downwind infants. 37 refs., 37 figs., 2 tabs.

  14. Reconstruction method for grating-based x-ray phase-contrast images without knowledge of the grating positions

    International Nuclear Information System (INIS)

    To retrieve the phase information of x-rays using a Talbot-Lau interferometer, the knowledge of the grating positions is mandatory. Transferring the interferometer technique from the laboratory to a conventional x-ray imaging system, this requirement is no longer guaranteed. This is due to distortions and vibrations which are coupled into the interferometer. Therefore, we applied a principal-component analysis to Talbot-Lau x-ray phase-contrast data. In experiments we compared this alternative approach for image reconstruction to the conventional procedure. As a result, a superior robustness of the principal-component analysis against imperfect phase-stepping data was found. Furthermore, using the proposed method, the reconstruction of x-ray phase-contrast images from randomly distributed phase-step positions is possible

  15. Optical reconstruction of digital off-axis Fresnel holograms using phase-only LCOS SLM 'HoloEye PLUTO VIS'

    International Nuclear Information System (INIS)

    Optical reconstruction of digital holograms using SLM is used for imaging of 3D scenes, interferometry, microscopy, and etc. In this article reconstruction of digital off-axis Fresnel holograms using phase-only LCOS SLM 'HoloEye PLUTO VIS' is described. Experimental and numerically simulated results of reconstruction are presented.

  16. 3D phase micro-object studies by means of digital holographic tomography supported by algebraic reconstruction technique

    Science.gov (United States)

    Bilski, B. J.; Jozwicka, A.; Kujawinska, M.

    2007-09-01

    Constant development of microelements' technology requires a creation of new instruments to determine their basic physical parameters in 3D. The most efficient non-destructive method providing 3D information is tomography. In this paper we present Digital Holographic Tomography (DHT), in which input data is provided by means of Di-git- al Holography (DH). The main advantage of DH is the capability to capture several projections with a single hologram [1]. However, these projections have uneven angular distribution and their number is significantly limited. Therefore - Algebraic Reconstruction Technique (ART), where a few phase projections may be sufficient for proper 3D phase reconstruction, is implemented. The error analysis of the method and its additional limitations due to shape and dimensions of investigated object are presented. Finally, the results of ART application to DHT method are also presented on data reconstructed from numerically generated hologram of a multimode fibre.

  17. Almost complete coherent state subsystems and partial reconstruction of wavefunctions in the Fock–Bargmann phase-number representation

    International Nuclear Information System (INIS)

    We provide (partial) reconstruction formulas and discrete Fourier transforms for wavefunctions in standard Fock–Bargmann (holomorphic) phase-number representation from a finite number N of phase samples {θk = 2πk/N}N−1k=0 for a given mean number p of particles. The resulting coherent state subsystem S={|zk=p1/2eiθk>} is complete (a frame) for truncated Hilbert spaces (finite number of particles) and reconstruction formulas are exact. For an unbounded number of particles, S is ‘almost complete’ (a pseudo-frame) and partial reconstruction formulas are provided along with a study of the accuracy of the approximation, which tends to be exact when p < N and/or N → ∞. This article is part of a special issue of Journal of Physics A: Mathematical and Theoretical devoted to ‘Coherent states: mathematical and physical aspects’. (paper)

  18. Optimal systolic and diastolic coronary artery imaging with Dual-source CT: comparison of automatic optimal phase selection technique and whole phase reconstruction

    International Nuclear Information System (INIS)

    Objective: The purpose of this study was to evaluate the optimal reconstruction phase of dual-source CT coronary angiography (CTCA), and to compare image quality of CTCA using automatic optimal phase selection technique and whole phase reconstruction. Methods: 107 patients underwent CTCA Optimal systolic and diastolic coronary arteries were selected automatically, image quality was scored using four-score method. Coronary arteries were segmented according to the guideline of American Heart Association. Image quality of CTCA using both techniques was compared Results: Optimal image quality of CTCA was acquired at the 70% of R-R interval (average score of 3.11), followed by 75% and 35% of R- R interval (average scores of 3.06 and 3.03, respectively). Average score of optimal systolic phase was 305; while average score of optimal diastolic phase was 3.08. There was no significant difference between both techniques On the basis of per-segment, there was significant difference of image quality in segment 4 (p value of less than 0.05). On the basis of coronary artery, there was no significant difference between both techniques. Conclusion: Optimal diastolic and systolic image quality of CTCA was acquired at the 70% and 35% of R-R interval Automatic optimal phase selection technique can satisfy clinical demands because of its sufficient image quality; however, its combination of whole phase reconstruction technique is necessary. (authors)

  19. High Performance Harmonic Isolation By Means of The Single-phase Series Active Filter Employing The Waveform Reconstruction Method

    DEFF Research Database (Denmark)

    Senturk, Osman Selcuk; Hava, Ahmet M.

    2009-01-01

    This paper proposes the Waveform Reconstruction Method (WRM), which is utilized in the single-phase Series Active Filter's (SAF's) control algorithm, in order to extract the load harmonic voltage component of voltage harmonic type single-phase diode rectifier loads. Employing WRM and the line...... current sampling delay reduction method (SDRM), a single-phase SAF compensated system provides higher harmonic isolation performance and higher stability margins compared to the system using conventional synchronous reference frame based methods. The analytical, simulation, and experimental studies of a 2.......5 kW single-phase SAF compensated system prove the theory....

  20. Terahertz in-line digital holography of dragonfly hindwing: amplitude and phase reconstruction at enhanced resolution by extrapolation

    OpenAIRE

    Rong, Lu; Latychevskaia, Tatiana; Wang, Dayong; Zhou, Xun; Huang, Haochong; Li, Zeyu; Wang, Yunxin

    2014-01-01

    We report here on terahertz (THz) digital holography on a biological specimen. A continuous-wave (CW) THz in-line holographic setup was built based on a 2.52 THz CO2 pumped THz laser and a pyroelectric array detector. We introduced novel statistical method of obtaining true intensity values for the pyroelectric array detector's pixels. Absorption and phase-shifting images of a dragonfly's hind wing were reconstructed simultaneously from single in-line hologram. Furthermore, we applied phase r...

  1. A compressed sensing based reconstruction algorithm for synchrotron source propagation-based X-ray phase contrast computed tomography

    Science.gov (United States)

    Melli, Seyed Ali; Wahid, Khan A.; Babyn, Paul; Montgomery, James; Snead, Elisabeth; El-Gayed, Ali; Pettitt, Murray; Wolkowski, Bailey; Wesolowski, Michal

    2016-01-01

    Synchrotron source propagation-based X-ray phase contrast computed tomography is increasingly used in pre-clinical imaging. However, it typically requires a large number of projections, and subsequently a large radiation dose, to produce high quality images. To improve the applicability of this imaging technique, reconstruction algorithms that can reduce the radiation dose and acquisition time without degrading image quality are needed. The proposed research focused on using a novel combination of Douglas-Rachford splitting and randomized Kaczmarz algorithms to solve large-scale total variation based optimization in a compressed sensing framework to reconstruct 2D images from a reduced number of projections. Visual assessment and quantitative performance evaluations of a synthetic abdomen phantom and real reconstructed image of an ex-vivo slice of canine prostate tissue demonstrate that the proposed algorithm is competitive in reconstruction process compared with other well-known algorithms. An additional potential benefit of reducing the number of projections would be reduction of time for motion artifact to occur if the sample moves during image acquisition. Use of this reconstruction algorithm to reduce the required number of projections in synchrotron source propagation-based X-ray phase contrast computed tomography is an effective form of dose reduction that may pave the way for imaging of in-vivo samples.

  2. A compressed sensing-based iterative algorithm for CT reconstruction and its possible application to phase contrast imaging

    Directory of Open Access Journals (Sweden)

    Li Xueli

    2011-08-01

    Full Text Available Abstract Background Computed Tomography (CT is a technology that obtains the tomogram of the observed objects. In real-world applications, especially the biomedical applications, lower radiation dose have been constantly pursued. To shorten scanning time and reduce radiation dose, one can decrease X-ray exposure time at each projection view or decrease the number of projections. Until quite recently, the traditional filtered back projection (FBP method has been commonly exploited in CT image reconstruction. Applying the FBP method requires using a large amount of projection data. Especially when the exposure speed is limited by the mechanical characteristic of the imaging facilities, using FBP method may prolong scanning time and cumulate with a high dose of radiation consequently damaging the biological specimens. Methods In this paper, we present a compressed sensing-based (CS-based iterative algorithm for CT reconstruction. The algorithm minimizes the l1-norm of the sparse image as the constraint factor for the iteration procedure. With this method, we can reconstruct images from substantially reduced projection data and reduce the impact of artifacts introduced into the CT reconstructed image by insufficient projection information. Results To validate and evaluate the performance of this CS-base iterative algorithm, we carried out quantitative evaluation studies in imaging of both software Shepp-Logan phantom and real polystyrene sample. The former is completely absorption based and the later is imaged in phase contrast. The results show that the CS-based iterative algorithm can yield images with quality comparable to that obtained with existing FBP and traditional algebraic reconstruction technique (ART algorithms. Discussion Compared with the common reconstruction from 180 projection images, this algorithm completes CT reconstruction from only 60 projection images, cuts the scan time, and maintains the acceptable quality of the

  3. Experimental evaluation of the 'transport-of-intensity' equation for magnetic phase reconstruction in Lorentz transmission electron microscopy.

    Science.gov (United States)

    Kohn, Amit; Habibi, Avihay; Mayo, Martin

    2016-01-01

    The 'transport-of-intensity' equation (TIE) is a general phase reconstruction methodology that can be applied to Lorentz transmission electron microscopy (TEM) through the use of Fresnel-contrast (defocused) images. We present an experimental study to test the application of the TIE for quantitative magnetic mapping in Lorentz TEM without aberration correction by examining sub-micrometer sized Ni80Fe20 (Permalloy) elements. For a JEOL JEM 2100F adapted for Lorentz microscopy, we find that quantitative magnetic phase reconstructions are possible for defoci distances ranging between approximately 200 μm and 800 μm. The lower limit originates from competing sources of image intensity variations in Fresnel-contrast images, namely structural defects and diffraction contrast. The upper defocus limit is due to a numerical error in the estimation of the intensity derivative based on three images. For magnetic domains, we show quantitative reconstructions of the product of the magnetic induction vector and thickness in element sizes down to approximately 100 nm in lateral size and 5 nm thick resulting in a minimal detection of 5Tnm. Three types of magnetic structures are tested in terms of phase reconstruction: vortex cores, domain walls, and element edges. We quantify vortex core structures at a diameter of 12 nm while the structures of domain walls and element edges are characterized qualitatively. Finally, we show by image simulations that the conclusions of this experimental study are relevant to other Lorentz TEM in which spherical aberration and defocus are dominant aberrations. PMID:26452194

  4. Fully-implicit orthogonal reconstructed Discontinuous Galerkin method for fluid dynamics with phase change

    Science.gov (United States)

    Nourgaliev, R.; Luo, H.; Weston, B.; Anderson, A.; Schofield, S.; Dunn, T.; Delplanque, J.-P.

    2016-01-01

    A new reconstructed Discontinuous Galerkin (rDG) method, based on orthogonal basis/test functions, is developed for fluid flows on unstructured meshes. Orthogonality of basis functions is essential for enabling robust and efficient fully-implicit Newton-Krylov based time integration. The method is designed for generic partial differential equations, including transient, hyperbolic, parabolic or elliptic operators, which are attributed to many multiphysics problems. We demonstrate the method's capabilities for solving compressible fluid-solid systems (in the low Mach number limit), with phase change (melting/solidification), as motivated by applications in Additive Manufacturing (AM). We focus on the method's accuracy (in both space and time), as well as robustness and solvability of the system of linear equations involved in the linearization steps of Newton-based methods. The performance of the developed method is investigated for highly-stiff problems with melting/solidification, emphasizing the advantages from tight coupling of mass, momentum and energy conservation equations, as well as orthogonality of basis functions, which leads to better conditioning of the underlying (approximate) Jacobian matrices, and rapid convergence of the Krylov-based linear solver.

  5. Oak Ridge Health Studies Phase 1 report, Volume 2: Part A, Dose Reconstruction Feasibility Study

    International Nuclear Information System (INIS)

    The Phase I feasibility study has focused on determining the availability of information for estimating exposures of the public to chemicals and radionuclides released as a result of historical operation of the facilities at the Oak Ridge Reservation (ORR). The estimation of such past exposures is frequently called dose reconstruction. The initial project tasks, Tasks 1 and 2 were designed to identify and collect information that documents the history of activities at the ORR that resulted in the release of contamination and to characterize the availability of data that could be used to estimate the magnitude of the contaminant releases or public exposures. A history of operations that are likely to have generated off-site releases has been documented as a result of Task 1 activities. The activities required to perform this task involved the extensive review of historical operation records and interviews with present and past employees as well as other knowledgeable individuals. The investigation process is documented in this report. The Task 1 investigations have led to the documentation of an overview of the activities that have taken place at each of the major complexes, including routine operations, waste management practices, special projects, and accidents and incidents. Historical activities that appear to warrant the highest priority in any further investigations were identified based on their likely association with off-site emissions of hazardous materials as indicated by the documentation reviewed or information obtained in interviews

  6. The validation of made-to-measure method for reconstruction of phase space distribution functions

    CERN Document Server

    Tagawa, Hiromichi; Yano, Taihei; Hara, Takuji

    2016-01-01

    We investigate how accurately phase space distribution functions (DFs) in galactic models can be reconstructed by a made-to-measure (M2M) method, which constructs $N$-particle models of stellar systems from photometric and various kinematic data. The advantage of the M2M method is that this method can be applied to various galactic models without assumption of the spatial symmetries of gravitational potentials adopted in galactic models, and furthermore, numerical calculations of the orbits of the stars cannot be severely constrained by the capacities of computer memories. The M2M method has been applied to various galactic models. However, the degree of accuracy for the recovery of DFs derived by the M2M method in galactic models has never been investigated carefully. Therefore, we show the degree of accuracy for the recovery of the DFs for the anisotropic Plummer model and the axisymmetric St\\"{a}ckel model, which have analytic solutions of the DFs. Furthermore, this study provides the dependence of the deg...

  7. Lattice structure for generalized-support multidimensional linear phase perfect reconstruction filter bank.

    Science.gov (United States)

    Gao, Xieping; Li, Bodong; Xiao, Fen

    2013-12-01

    Multidimensional linear phase perfect reconstruction filter bank (MDLPPRFB) can be designed and implemented via lattice structure. The lattice structure for the MDLPPRFB with filter support N(MΞ) has been published by Muramatsu , where M is the decimation matrix, Ξ is a positive integer diagonal matrix, and N(N) denotes the set of integer vectors in the fundamental parallelepiped of the matrix N. Obviously, if Ξ is chosen to be other positive diagonal matrices instead of only positive integer ones, the corresponding lattice structure would provide more choices of filter banks, offering better trade-off between filter support and filter performance. We call such resulted filter bank as generalized-support MDLPPRFB (GSMDLPPRFB). The lattice structure for GSMDLPPRFB, however, cannot be designed by simply generalizing the process that Muramatsu employed. Furthermore, the related theories to assist the design also become different from those used by Muramatsu . Such issues will be addressed in this paper. To guide the design of GSMDLPPRFB, the necessary and sufficient conditions are established for a generalized-support multidimensional filter bank to be linear-phase. To determine the cases we can find a GSMDLPPRFB, the necessary conditions about the existence of it are proposed to be related with filter support and symmetry polarity (i.e., the number of symmetric filters ns and antisymmetric filters na). Based on a process (different from the one Muramatsu used) that combines several polyphase matrices to construct the starting block, one of the core building blocks of lattice structure, the lattice structure for GSMDLPPRFB is developed and shown to be minimal. Additionally, the result in this paper includes Muramatsu's as a special case. PMID:23974625

  8. GPU-based rapid reconstruction of cellular 3D refractive index maps from tomographic phase microscopy (Conference Presentation)

    Science.gov (United States)

    Dardikman, Gili; Shaked, Natan T.

    2016-03-01

    We present highly parallel and efficient algorithms for real-time reconstruction of the quantitative three-dimensional (3-D) refractive-index maps of biological cells without labeling, as obtained from the interferometric projections acquired by tomographic phase microscopy (TPM). The new algorithms are implemented on the graphic processing unit (GPU) of the computer using CUDA programming environment. The reconstruction process includes two main parts. First, we used parallel complex wave-front reconstruction of the TPM-based interferometric projections acquired at various angles. The complex wave front reconstructions are done on the GPU in parallel, while minimizing the calculation time of the Fourier transforms and phase unwrapping needed. Next, we implemented on the GPU in parallel the 3-D refractive index map retrieval using the TPM filtered-back projection algorithm. The incorporation of algorithms that are inherently parallel with a programming environment such as Nvidia's CUDA makes it possible to obtain real-time processing rate, and enables high-throughput platform for label-free, 3-D cell visualization and diagnosis.

  9. Optimized projection binning for improved helical amplitude- and phase-based 4DCT reconstruction in the presence of breathing irregularity

    Science.gov (United States)

    Werner, René; Hofmann, Christian; Gauer, Tobias

    2016-03-01

    Respiration-correlated CT (4DCT) forms the basis of clinical 4D radiotherapy workflows for patients with thoracic and abdominal lesions. 4DCT image data, however, often suffers from motion artifacts due to unfulfilled assumptions during reconstruction and image/projection data sorting. In this work and focusing on low-pitch helical scanning protocols, two questionable assumptions are addressed: (1) the need for regular breathing patterns and (2) a constant correlation between the external breathing signal acquired for image/projection sorting and internal motion patterns. To counteract (1), a patient-specific upper breathing signal amplitude threshold is introduced to avoid artifacts due to unusual deep inspiration (helpful for both amplitude- and phase-based reconstruction). In addition, a projection data binning algorithm based on a statistical analysis of the patient's breathing signal is proposed to stabilize phase-based sorting. To further alleviate the need for (2), an image artifact metric is incorporated into and minimized during the reconstruction process. The optimized reconstruction is evaluated using 30 clinical 4DCT data sets and demonstrated to significantly reduce motion artifacts.

  10. A surface profile reconstruction system using sinusoidal phase-modulating interferometry and fiber-optic fringe projection

    Science.gov (United States)

    En, Bo; Fa-jie, Duan; Chang-rong, Lv; Fan, Feng; Xiao, Fu

    2014-06-01

    A fiber-optic sinusoidal phase modulating (SPM) interferometer for surface profile reconstruction is presented. Sinusoidal phase modulation is created by modulating the drive voltage of the piezoelectric transducer. The surface profile is constructed basing on fringe projection. Fringe patterns are vulnerable to external disturbances such as temperature fluctuation and mechanical vibration, which cause phase drift and decrease measuring accuracy. We build a closed-loop feedback phase compensation system, the bias value of external disturbances superimposed on fringe patterns can be reduced to about 50 mrad, and the phase stability for interference fringes is less than 5.76 mrad. By measuring the surface profile of a paper plate for two times, the repeatability is estimated to be about 11 nm, and is equivalent to be about λ/69. For a plane with 100 × 100 points, a single measurement takes less than 140 ms, and the feasibility for real-time profile measurement with high accuracy has been verified.

  11. Phase Space Reconstruction from Econommic Time Series Data: Improving Models of Complex Real-World Dynamic Systems

    Directory of Open Access Journals (Sweden)

    Ray Huffaker

    2010-10-01

    Full Text Available  Failure of economic models to anticipate the global financial crisis illustrates the need for modeling to better capture complex real-world dynamics. Conventional models—in which economic variables evolve toward equilibria or fluctuate about equilibria in response to exogenous random shocks—are ill-equipped to portray complex real-world dynamics in which economic variables may cycle aperiodically along low-dimensional ‘strange attractors’. We present a method developed in the physics literature—‘phase space reconstruction’—that reconstructs strange attractors present in real-world dynamical systems using time series data on a single variable. Phase space reconstruction provides pictures of real-world dynamics that can guide model specification.

  12. Terahertz in-line digital holography of dragonfly hindwing: amplitude and phase reconstruction at enhanced resolution by extrapolation

    CERN Document Server

    Rong, Lu; Wang, Dayong; Zhou, Xun; Huang, Haochong; Li, Zeyu; Wang, Yunxin

    2014-01-01

    We report here on terahertz (THz) digital holography on a biological specimen. A continuous-wave (CW) THz in-line holographic setup was built based on a 2.52 THz CO2 pumped THz laser and a pyroelectric array detector. We introduced novel statistical method of obtaining true intensity values for the pyroelectric array detector's pixels. Absorption and phase-shifting images of a dragonfly's hind wing were reconstructed simultaneously from single in-line hologram. Furthermore, we applied phase retrieval routines to eliminate twin image and enhanced the resolution of the reconstructions by hologram extrapolation beyond the detector area. The finest observed features are 35 {\\mu}m width cross veins.

  13. Optimal image reconstruction phase at low and high heart rates in dual-source CT coronary angiography.

    Science.gov (United States)

    Araoz, Philip A; Kirsch, Jacobo; Primak, Andrew N; Braun, Natalie N; Saba, Osama; Williamson, Eric E; Harmsen, W Scott; Mandrekar, Jayawant N; McCollough, Cynthia H

    2009-12-01

    The purpose of this study was to determine the cardiac phase having the highest coronary sharpness for low and high heart rate patients scanned with dual source CT (DSCT) and to compare coronary image sharpness over different cardiac phases. DSCT coronary CT scans for 30 low heart rate (70 bpm) patients were reconstructed into different cardiac phases, starting at 30% and increasing at 5% increments until 70%. A blinded observer graded image sharpness per coronary segment, from which sharpness scores were produced for the right (RCA), left main (LM), left anterior descending (LAD), and circumflex (Cx) coronary arteries. For each coronary artery, the phase with maximal image sharpness was identified with repeated measures analysis of variance. Comparison of coronary sharpness between low and high heart rate patients was made using generalized estimating equations. For low heart rates the highest sharpness scores for all four vessels (RCA, LM, LAD, and Cx) were at the 65 or 70% phase, which are end-diastolic cardiac phases. For high heart rates the highest sharpness scores were between the 35 and 45% phases, which are end-systolic phases. Low heart rate patients had higher coronary sharpness at most cardiac phases; however, patients with high heart rates had higher coronary sharpness in the 45% phase for all four vessels (P < 0.0001). Using DSCT scanning, optimal image sharpness is obtained in end-diastole at low heart rates and in end-systole in high heart rates. PMID:19669664

  14. Reconstruction of gyrotropic phase-space distributions from one-dimensional projections

    DEFF Research Database (Denmark)

    Egedal, J.; Bindslev, H.

    2004-01-01

    This paper describes mathematical tools applicable to the reconstruction of anisotropic velocity distributions through the unfolding of data coming from techniques like collective Thomson scattering or laser induced fluorescence, where one-dimensional projections of the velocity space along...

  15. Terahertz in-line digital holography of dragonfly hindwing: amplitude and phase reconstruction at enhanced resolution by extrapolation

    OpenAIRE

    Rong, Lu; Latychevskaia, Tatiana; Wang, Dayong; Zhou, Xun; Huang, Haochong; Li, Zeyu; Wang, Yunxin

    2014-01-01

    We report here on terahertz (THz) digital holography on a biological specimen. A continuous-wave (CW) THz in-line holographic setup was built based on a 2.52 THz CO2 pumped THz laser and a pyroelectric array detector. We introduced novel statistical method of obtaining true intensity values for the pyroelectric array detector’s pixels. Absorption and phase-shifting images of a dragonfly’s hindwing were reconstructed simultaneously from single in-line hologram. Furthermore, we applied phase re...

  16. Reconstructing brain magnetic susceptibility distributions from T2* phase images by TV-regularized 2-subproblem split Bregman iterations

    Directory of Open Access Journals (Sweden)

    Chen Z

    2014-03-01

    Full Text Available Zikuan Chen,1 Vince D Calhoun1,21The Mind Research Network and LBERI, Albuquerque, NM, USA; 2University of New Mexico, ECE Dept, Albuquerque, NM, USAAbstract: The underlying source of brain imaging by T2*-weighted magnetic resonance imaging (T2*MRI is mainly due to the intracranial inhomogeneous magnetic susceptibility distribution (denoted by χ. We can reconstruct the source χ by two computational steps: first, calculate a fieldmap from a T2* phase image and then second, calculate a χ map from the fieldmap. The internal χ distribution reconstruction from observed T2* phase images is termed χ tomography, which connotes the digital source reproduction with spatial conformance by solving inverse problems in the context of medical imaging. In the small phase angle regime, the T2* phase image remains unwrapped (−π<phase angle<π and it is linearly related to the fieldmap by a scaling factor. However, the second inverse step (calculating a χ map from a fieldmap is a severely ill-posed 3D deconvolution problem due to an unusual bipolar-valued kernel (dipole field kernel. We have reported on a 3-subproblem split Bregman iteration algorithm for total variation-regularized 3D χ reconstruction; in this paper, we report on a 2-subproblem split Bregman iteration algorithm with easy implementation. We validate the 3D χ tomography algorithms by numerical simulations and phantom experiments. We also demonstrate the feasibility of 3D χ tomography for obtaining in vivo brain χ states at 2 mm spatial resolution.Keywords: T2*-weighted MRI (T2*MRI, magnetic susceptibility tomography (χ tomography, dipole effect, 3D deconvolution, filter truncation, total variation (TV, split Bregman iteration, computed inverse magnetic resonance imaging (CIMRI

  17. Phase reconstruction from velocity-encoded MRI measurements – A survey of sparsity-promoting variational approaches

    KAUST Repository

    Benning, Martin

    2014-01-01

    In recent years there has been significant developments in the reconstruction of magnetic resonance velocity images from sub-sampled k-space data. While showing a strong improvement in reconstruction quality compared to classical approaches, the vast number of different methods, and the challenges in setting them up, often leaves the user with the difficult task of choosing the correct approach, or more importantly, not selecting a poor approach. In this paper, we survey variational approaches for the reconstruction of phase-encoded magnetic resonance velocity images from sub-sampled k-space data. We are particularly interested in regularisers that correctly treat both smooth and geometric features of the image. These features are common to velocity imaging, where the flow field will be smooth but interfaces between the fluid and surrounding material will be sharp, but are challenging to represent sparsely. As an example we demonstrate the variational approaches on velocity imaging of water flowing through a packed bed of solid particles. We evaluate Wavelet regularisation against Total Variation and the relatively recent second order Total Generalised Variation regularisation. We combine these regularisation schemes with a contrast enhancement approach called Bregman iteration. We verify for a variety of sampling patterns that Morozov\\'s discrepancy principle provides a good criterion for stopping the iterations. Therefore, given only the noise level, we present a robust guideline for setting up a variational reconstruction scheme for MR velocity imaging. © 2013 Elsevier Inc. All rights reserved.

  18. Linear and mass attenuation coefficient for CdTe compound of X-rays from 10 to 100 keV energy range in different phases

    International Nuclear Information System (INIS)

    The Full Potential Linear Muffin Tin Orbitals method within the density functional theory has been utilized to calculate structural and electronic properties of the CdTe compound. We have checked that the CdTe has two phase-transitions from zinc-blend to cinnabar and from cinnabar to rocksalt. We have found that the rigidity, the energy and the nature of the gap change according to the phase change, so we can predict that a CdTe detector may have different behaviors in different phase conditions. In order to investigate this behavior change, the linear and the mass attenuation coefficients of X-ray in rocksalt, zinc-blend and cinnabar structures are calculated from 10 keV to100 keV, using the XCOM data. We have found that when CdTe undergoes a phase transition from zinc-blend to cinnabar, its linear attenuation coefficient decreases down to a value of about 100 times smaller than its initial one, and when it undergoes a transition from cinnabar to rocksalt it increases up to a value about 90 times larger than its initial one

  19. Linear and mass attenuation coefficient for CdTe compound of X-rays from 10 to 100 keV energy range in different phases

    Energy Technology Data Exchange (ETDEWEB)

    Saim, A., E-mail: saim1989asma@gmail.com; Tebboune, A.; Berkok, H.; Belameiri, N.; Belbachir, A.H.

    2014-07-25

    The Full Potential Linear Muffin Tin Orbitals method within the density functional theory has been utilized to calculate structural and electronic properties of the CdTe compound. We have checked that the CdTe has two phase-transitions from zinc-blend to cinnabar and from cinnabar to rocksalt. We have found that the rigidity, the energy and the nature of the gap change according to the phase change, so we can predict that a CdTe detector may have different behaviors in different phase conditions. In order to investigate this behavior change, the linear and the mass attenuation coefficients of X-ray in rocksalt, zinc-blend and cinnabar structures are calculated from 10 keV to100 keV, using the XCOM data. We have found that when CdTe undergoes a phase transition from zinc-blend to cinnabar, its linear attenuation coefficient decreases down to a value of about 100 times smaller than its initial one, and when it undergoes a transition from cinnabar to rocksalt it increases up to a value about 90 times larger than its initial one.

  20. Phase-shifting digital holography in image reconstruction%基于数字移相全息的图像重构

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A phase-shifting digital holography scheme developed to investigate internal defects in artworks is described. Phase-shifting is utilized to obtain a clear reconstructed object wave from a rough surface texture. A reverse-transform algorithm is employed to reconstruct the object wave on its original position of unknown distance or the imaging position from the object wave information on the holographic plane. To get the clearest reconstruction the exact registration of the unknown distance is determined by applying the intensity sum as the auto-focusing function. The spatial resolution of the reconstruction image is also investigated for a variety of affecting factors. Laboratory results of reconstruction images under deformation are presented.

  1. Evaluation of alias-less reconstruction by pseudo-parallel imaging in a phase-scrambling fourier transform technique

    International Nuclear Information System (INIS)

    We propose an image reconstruction technique in which parallel image reconstruction is performed based on the sensitivity encoding (SENSE) algorithm using only a single set of signals. The signal obtained in the phase-scrambling Fourier transform (PSFT) imaging technique can be transformed to the signal described by the Fresnel transform of the objects, which is known as the diffracted wave-front equation of the object in acoustics or optics. Since the Fresnel transform is a convolution integral on the object space, the space where the PSFT signal exists can be considered as both in the Fourier domain and in the object domain. This notable feature indicates that weighting functions corresponding to the sensitivity of radiofrequency (RF) coils can be approximately given in the PSFT signal space. Therefore, we can obtain two folded images from a single set of signals with different weighting functions, and image reconstruction based on the SENSE parallel imaging algorithm is possible using a series of folded images. Simulation and experimental studies showed that almost alias-free images can be synthesized using a single signal that does not satisfy the sampling theorem. (author)

  2. Importance of phase unwrapping for the reconstruction of microwave tomographic images

    OpenAIRE

    Grzegorczyk, Tomasz M.; Meaney, Paul M.; Jeon, Soon Ik; Geimer, Shireen D.; Paulsen, Keith D.

    2011-01-01

    Microwave image reconstruction is typically based on a regularized least-square minimization of either the complex-valued field difference between recorded and modeled data or the logarithmic transformation of these field differences. Prior work has shown anecdotally that the latter outperforms the former in limited surveys of simulated and experimental phantom results. In this paper, we provide a theoretical explanation of these empirical findings by developing closed form solutions for the ...

  3. Numerical Simulation of Two Phase Flow in Reconstructed Pore Network Based on Lattice Boltzmann Method

    OpenAIRE

    Song Rui; Liu Jianjun; Qin Dahui

    2013-01-01

    Accurate prediction and understanding of the disorder microstructures in the porous media contribute to acquiring the macroscopic physical properties such as conductivity, permeability, formation factor, elastic moduli etc. Based on the rock serial sectioning images of Berea sandstone acquired by the core scanning system developed by our research group, the reconstructed rock model is established in the Mimics software and the extracted pore network of the porous rock is accomplished by the s...

  4. A Discrete Phase-Space Calculus for Quantum Spins based on a Reconstruction Method using Coherent States

    CERN Document Server

    Weigert, S

    1999-01-01

    To reconstruct a mixed or pure quantum state of a spin s is possible through coherent states: its density matrix is fixed by the probabilities to measure the value s along 4s(s+1) appropriately chosen directions in space. Thus, after inverting the experimental data, the statistical operator is parametrized entirely by expectation values. On this basis, a symbolic calculus for quantum spins is developed, the `expectation-value representation.' It resembles the Moyal representation for SU(2) but two important differences exist. On the one hand, the symbols take values on a discrete set of points in phase space only. On the other hand, no quasi-probabilities - that is, phase-space distributions with negative values - are encountered in this approach.

  5. Time-resolved computed tomography of the liver: retrospective, multi-phase image reconstruction derived from volumetric perfusion imaging

    International Nuclear Information System (INIS)

    To assess feasibility and image quality (IQ) of a new post-processing algorithm for retrospective extraction of an optimised multi-phase CT (time-resolved CT) of the liver from volumetric perfusion imaging. Sixteen patients underwent clinically indicated perfusion CT using 4D spiral mode of dual-source 128-slice CT. Three image sets were reconstructed: motion-corrected and noise-reduced (MCNR) images derived from 4D raw data; maximum and average intensity projections (time MIP/AVG) of the arterial/portal/portal-venous phases and all phases (total MIP/ AVG) derived from retrospective fusion of dedicated MCNR split series. Two readers assessed the IQ, detection rate and evaluation time; one reader assessed image noise and lesion-to-liver contrast. Time-resolved CT was feasible in all patients. Each post-processing step yielded a significant reduction of image noise and evaluation time, maintaining lesion-to-liver contrast. Time MIPs/AVGs showed the highest overall IQ without relevant motion artefacts and best depiction of arterial and portal/portal-venous phases respectively. Time MIPs demonstrated a significantly higher detection rate for arterialised liver lesions than total MIPs/AVGs and the raw data series. Time-resolved CT allows data from volumetric perfusion imaging to be condensed into an optimised multi-phase liver CT, yielding a superior IQ and higher detection rate for arterialised liver lesions than the raw data series. (orig.)

  6. Single-shot dual-wavelength phase reconstruction in off-axis digital holography with polarization-multiplexing transmission.

    Science.gov (United States)

    Wang, Zhe; Jiang, Zhuqing; Chen, Yifei

    2016-08-01

    A new system for single-shot dual-wavelength digital holographic microscopy with polarization-multiplexing path-shared transmission is presented. The key feature of the optical configuration is that the interference waves of two wavelengths having orthogonal polarization can transmit in the same interferometer paths at the same time, and two polarizers orthogonal to each other are placed in front of the CCD to realize single-shot recording of two holograms. The correlative filtering algorithm of the spatial-frequency spectrum for dual-wavelength digital holograms is reliable and efficient in the dual-wavelength path-shared configuration. The phase reconstruction in dual-wavelength digital holographic imaging is achieved by using this filtering algorithm. The experiment results of phase reconstruction of a groove grating demonstrate the reliability and validity of this optical configuration and the correlative filtering algorithm. This polarization-multiplexing configuration for dual-wavelength digital holography is compact and has more flexibility for the replacement of different-wavelength lasers. PMID:27505390

  7. A Quadratic Spline based Interface (QUASI) reconstruction algorithm for accurate tracking of two-phase flows

    Science.gov (United States)

    Diwakar, S. V.; Das, Sarit K.; Sundararajan, T.

    2009-12-01

    A new Quadratic Spline based Interface (QUASI) reconstruction algorithm is presented which provides an accurate and continuous representation of the interface in a multiphase domain and facilitates the direct estimation of local interfacial curvature. The fluid interface in each of the mixed cells is represented by piecewise parabolic curves and an initial discontinuous PLIC approximation of the interface is progressively converted into a smooth quadratic spline made of these parabolic curves. The conversion is achieved by a sequence of predictor-corrector operations enforcing function ( C0) and derivative ( C1) continuity at the cell boundaries using simple analytical expressions for the continuity requirements. The efficacy and accuracy of the current algorithm has been demonstrated using standard test cases involving reconstruction of known static interface shapes and dynamically evolving interfaces in prescribed flow situations. These benchmark studies illustrate that the present algorithm performs excellently as compared to the other interface reconstruction methods available in literature. Quadratic rate of error reduction with respect to grid size has been observed in all the cases with curved interface shapes; only in situations where the interface geometry is primarily flat, the rate of convergence becomes linear with the mesh size. The flow algorithm implemented in the current work is designed to accurately balance the pressure gradients with the surface tension force at any location. As a consequence, it is able to minimize spurious flow currents arising from imperfect normal stress balance at the interface. This has been demonstrated through the standard test problem of an inviscid droplet placed in a quiescent medium. Finally, the direct curvature estimation ability of the current algorithm is illustrated through the coupled multiphase flow problem of a deformable air bubble rising through a column of water.

  8. Phase reconstruction from multiple coil data using a virtual reference coil

    Science.gov (United States)

    Parker, Dennis L.; Payne, Allison; Todd, Nick; Hadley, J. Rock

    2013-01-01

    Purpose This paper develops a method to obtain optimal estimates of absolute magnetization phase from multiple-coil MRI data. Methods The element-specific phases of a multi-element receiver coil array are accounted for by using the phase of a real or virtual reference coil that is sensitive over the entire imaged volume. The virtual-reference coil is generated as a weighted combination of measurements from all receiver coils. The phase-corrected multiple coil complex images are combined using the inverse covariance matrix. These methods are tested on images of an agar phantom, an in vivo breast, and an anesthetized rabbit obtained using combinations of four, nine, and three receiver channels, respectively. Results The four- and three- channel acquisitions require formation of a virtual-reference receiver coil while one channel of the nine-channel receive array has a sensitivity profile covering the entire imaged volume. Referencing to a real or virtual coil gives receiver phases that are essentially identical except for the individual receiver channel noise. The resulting combined images, which account for receiver channel noise covariance, show the expected reduction in phase variance. Conclusions The proposed virtual reference coil method determines a phase distribution for each coil from which an optimal phase map can be obtained. PMID:24006172

  9. 3D mouse shape reconstruction based on phase-shifting algorithm for fluorescence molecular tomography imaging system.

    Science.gov (United States)

    Zhao, Yue; Zhu, Dianwen; Baikejiang, Reheman; Li, Changqing

    2015-11-10

    This work introduces a fast, low-cost, robust method based on fringe pattern and phase shifting to obtain three-dimensional (3D) mouse surface geometry for fluorescence molecular tomography (FMT) imaging. We used two pico projector/webcam pairs to project and capture fringe patterns from different views. We first calibrated the pico projectors and the webcams to obtain their system parameters. Each pico projector/webcam pair had its own coordinate system. We used a cylindrical calibration bar to calculate the transformation matrix between these two coordinate systems. After that, the pico projectors projected nine fringe patterns with a phase-shifting step of 2π/9 onto the surface of a mouse-shaped phantom. The deformed fringe patterns were captured by the corresponding webcam respectively, and then were used to construct two phase maps, which were further converted to two 3D surfaces composed of scattered points. The two 3D point clouds were further merged into one with the transformation matrix. The surface extraction process took less than 30 seconds. Finally, we applied the Digiwarp method to warp a standard Digimouse into the measured surface. The proposed method can reconstruct the surface of a mouse-sized object with an accuracy of 0.5 mm, which we believe is sufficient to obtain a finite element mesh for FMT imaging. We performed an FMT experiment using a mouse-shaped phantom with one embedded fluorescence capillary target. With the warped finite element mesh, we successfully reconstructed the target, which validated our surface extraction approach. PMID:26560789

  10. Reconstructing very short TE phase rotation spectral data collected with multichannel phased-array coils at 3 T.

    Science.gov (United States)

    Wijtenburg, S Andrea; Knight-Scott, Jack

    2011-09-01

    Phased-array volume coils were used in conjunction with the phase rotation STEAM (PR-STEAM) spectroscopy technique to acquire very short TE data from the anterior cingulate gyrus at 3 T. A method for combining PR-STEAM data from multiple subcoils is presented. The data were acquired from seven healthy participants using PR-STEAM (repetition time/mixing time/echo time=3500/10/6.5 ms, 6 cm(3), NEX=128, spectral width=2000 Hz, 2048 complex points, Δφ(1)=135°, Δφ(2)=22.5°, Δφ(3)=112.5° and Δφ(ADC)=0°). In addition to the primary metabolites, LCModel fit results suggest that glutathione and glutamate can also be identified with Cramér-Rao lower bounds of 10% or less. PMID:21550744

  11. Computational model design specification for Phase 1 of the Hanford Environmental Dose Reconstruction Project

    Energy Technology Data Exchange (ETDEWEB)

    Napier, B.A.

    1991-07-01

    The objective of the Hanford Environmental Dose Reconstruction (HEDR) Project is to estimate the radiation dose that individuals could have received as a result of emission from nuclear operations at Hanford since their inception in 1944. The purpose of this report is to outline the basic algorithm and necessary computer calculations to be used to calculate radiation doses specific and hypothetical individuals in the vicinity of Hanford. The system design requirements, those things that must be accomplished, are defined. The system design specifications, the techniques by which those requirements are met, are outlined. Included are the basic equations, logic diagrams, and preliminary definition of the nature of each input distribution. 4 refs., 10 figs., 9 tabs.

  12. Fermi-Surface Reconstruction and Complex Phase Equilibria in CaFe2As2

    Science.gov (United States)

    Gofryk, K.; Saparov, B.; Durakiewicz, T.; Chikina, A.; Danzenbächer, S.; Vyalikh, D. V.; Graf, M. J.; Sefat, A. S.

    2014-05-01

    Fermi-surface topology governs the relationship between magnetism and superconductivity in iron-based materials. Using low-temperature transport, angle-resolved photoemission, and x-ray diffraction, we show unambiguous evidence of large Fermi-surface reconstruction in CaFe2As2 at magnetic spin-density-wave and nonmagnetic collapsed-tetragonal (cT) transitions. For the cT transition, the change in the Fermi-surface topology has a different character with no contribution from the hole part of the Fermi surface. In addition, the results suggest that the pressure effect in CaFe2As2 is mainly leading to a rigid-band-like change of the valence electronic structure. We discuss these results and their implications for magnetism and superconductivity in this material.

  13. Computational model design specification for Phase 1 of the Hanford Environmental Dose Reconstruction Project

    International Nuclear Information System (INIS)

    The objective of the Hanford Environmental Dose Reconstruction (HEDR) Project is to estimate the radiation dose that individuals could have received as a result of emission from nuclear operations at Hanford since their inception in 1944. The purpose of this report is to outline the basic algorithm and necessary computer calculations to be used to calculate radiation doses specific and hypothetical individuals in the vicinity of Hanford. The system design requirements, those things that must be accomplished, are defined. The system design specifications, the techniques by which those requirements are met, are outlined. Included are the basic equations, logic diagrams, and preliminary definition of the nature of each input distribution. 4 refs., 10 figs., 9 tabs

  14. Musical interfaces: visualization and reconstruction of music with a microfluidic two-phase flow.

    Science.gov (United States)

    Mak, Sze Yi; Li, Zida; Frere, Arnaud; Chan, Tat Chuen; Shum, Ho Cheung

    2014-01-01

    Detection of sound wave in fluids can hardly be realized because of the lack of approaches to visualize the very minute sound-induced fluid motion. In this paper, we demonstrate the first direct visualization of music in the form of ripples at a microfluidic aqueous-aqueous interface with an ultra-low interfacial tension. The interfaces respond to sound of different frequency and amplitude robustly with sufficiently precise time resolution for the recording of musical notes and even subsequent reconstruction with high fidelity. Our work shows the possibility of sensing and transmitting vibrations as tiny as those induced by sound. This robust control of the interfacial dynamics enables a platform for investigating the mechanical properties of microstructures and for studying frequency-dependent phenomena, for example, in biological systems. PMID:25327509

  15. 3D optical phase reconstruction within PMMA samples using a spectral OCT system

    Science.gov (United States)

    Briones-R., Manuel d. J.; De La Torre-Ibarra, Manuel H.; Mendoza Santoyo, Fernando

    2015-08-01

    The optical coherence tomography (OCT) technique has proved to be a useful method in biomedical areas such as ophthalmology, dentistry, dermatology, among many others. In all these applications the main target is to reconstruct the internal structure of the samples from which the physician's expertise may recognize and diagnose the existence of a disease. Nowadays OCT has been applied one step further and is used to study the mechanics of some particular type of materials, where the resulting information involves more than just their internal structure and the measurement of parameters such as displacements, stress and strain. Here we report on a spectral OCT system used to image the internal 3D microstructure and displacement maps from a PMMA (Poly-methyl-methacrylate) sample, subjected to a deformation by a controlled three point bending and tilting. The internal mechanical response of the polymer is shown as consecutive 2D images.

  16. Musical Interfaces: Visualization and Reconstruction of Music with a Microfluidic Two-Phase Flow

    Science.gov (United States)

    Mak, Sze Yi; Li, Zida; Frere, Arnaud; Chan, Tat Chuen; Shum, Ho Cheung

    2014-10-01

    Detection of sound wave in fluids can hardly be realized because of the lack of approaches to visualize the very minute sound-induced fluid motion. In this paper, we demonstrate the first direct visualization of music in the form of ripples at a microfluidic aqueous-aqueous interface with an ultra-low interfacial tension. The interfaces respond to sound of different frequency and amplitude robustly with sufficiently precise time resolution for the recording of musical notes and even subsequent reconstruction with high fidelity. Our work shows the possibility of sensing and transmitting vibrations as tiny as those induced by sound. This robust control of the interfacial dynamics enables a platform for investigating the mechanical properties of microstructures and for studying frequency-dependent phenomena, for example, in biological systems.

  17. Cosmic flows and the expansion of the local Universe from non-linear phase-space reconstructions

    Science.gov (United States)

    Heß, Steffen; Kitaura, Francisco-Shu

    2016-03-01

    In this work, we investigate the impact of cosmic flows and density perturbations on Hubble constant H0 measurements using non-linear phase-space reconstructions of the Local Universe (LU). In particular, we rely on a set of 25 precise constrained N-body simulations based on Bayesian initial conditions reconstructions of the LU using the Two-Micron Redshift Survey galaxy sample within distances of about 90 h-1 Mpc. These have been randomly extended up to volumes enclosing distances of 360 h-1 Mpc with augmented Lagrangian perturbation theory (750 simulations in total), accounting in this way for gravitational mode coupling from larger scales, correcting for periodic boundary effects, and estimating systematics of missing attractors (σlarge = 134 s-1 km). We report on Local Group (LG) speed reconstructions, which for the first time are compatible with those derived from cosmic microwave background-dipole measurements: |vLG| = 685 ± 137 s-1 km. The direction (l, b) = (260.5° ± 13.3°, 39.1 ± 10.4°) is found to be compatible with the observations after considering the variance of large scales. Considering this effect of large scales, our local bulk flow estimations assuming a Λ cold dark matter model are compatible with the most recent estimates based on velocity data derived from the Tully-Fisher relation. We focus on low-redshift supernova measurements out to 0.01 positive bias in H0. Taking these effects into account yields a correction of ΔH0 = -1.76 ± 0.21 s- 1 km Mpc- 1, thereby reducing the tension between local probes and more distant probes. Effectively H0 is lower by about 2 per cent.

  18. Identification of the stimulated-emission threshold in high-β nanoscale lasers through phase-space reconstruction

    International Nuclear Information System (INIS)

    Nanoscale lasers sustain a few optical modes so that the fraction of spontaneous emission β funnelled into the useful (lasing) mode is high (of the order of 10-1) and the threshold, which traditionally corresponds to an abrupt kink in the light-in-light-out curve, becomes ill defined. We propose an alternative definition of the threshold that is based on the dynamical response of the laser and is valid even for β=1 lasers. The laser dynamics is analyzed through a reconstruction of its phase-space trajectory for pulsed excitations. Crossing the threshold, brings about a change in the shape of the trajectory and in the area contained in it. An unambiguous determination of the threshold in terms of this change is shown theoretically and illustrated experimentally in a photonic-crystal laser.

  19. Availability of MCNP & MATLAB for reconstructing the water-vapor two-phase flow pattern in neutron radiography

    Institute of Scientific and Technical Information of China (English)

    FENG Qixi; FENG Quanke; TAKESHI Kawai

    2008-01-01

    The China Advanced Research Reactor (CARR) is scheduled to be operated in the autumn of 2008. In this paper, we report preparations for installing the neutron radiography instrument (NRI) and for utilizing it efficiently. The 2-D relative neutron intensity profiles for the water-vapor two-phase flow inside the tube were obtained using the MCNP code without influence of γ-ray and electronic-noise. The MCNP simulation of the 2-D neutron intensity profile for the water-vapor two-phase flow was demonstrated. The simulated 2-D neutron intensity profiles could be used as the benchmark data base by calibrating part of the data measured by the CARR-NRI. The 3-D objective images allow us to understand the flow pattern more clearly and it is reconstructed using the MATLAB through the threshold transformation techniques. And thus it is concluded that the MCNP code and the MATLAB are very useful for constructing the benchmark data base for the investigation of the water-vapor two-phase flow using the CARR-NRI.

  20. GPU accelerated iterative SENSE reconstruction of radial phase encoded whole-heart MRI

    DEFF Research Database (Denmark)

    Sørensen, Thomas Sangild; Prieto, Claudia; Atkinson, David;

    2010-01-01

    Isotropic whole-heart imaging has become an important protocol in simplifying cardiac MRI. The acquisition time can however be a prohibiting factor. To reduce acquisition times a 3D scheme combining Cartesian sampling in the readout direction with radial sampling in the phase encoding plane was r...... time can be brought to a clinically acceptable level using commodity graphics hardware (GPUs)....

  1. Oak Ridge Health Studies Phase 1 report, Volume 2: Part C, Dose Reconstruction Feasibility Study

    International Nuclear Information System (INIS)

    A significant number of information sources have been identified that are relevant to historical locations and activities of populations potentially affected by releases from the Oak Ridge Reservation. The information that has been reviewed as part of this Task 5 investigation has shown that numerous residences and farms have historically been present near the ORR boundary and that a variety of land uses and recreational activities have been practiced. Based on this information alone, it would appear that many routes of off-site exposure could have been plausible. Most of the available published information addresses demographic and land use data on a regional or county-wide basis over fairly broad time periods. The information sources that are most readily available do not support direct evaluation of potential exposure pathways at specific geographic locations near the Oak Ridge facilities at specific points in time. A number of information sources have been identified that can provide demography and land use information more specific to locations and time periods that are identified to be of interest. Examples of data sources in this category include individual USGS topographic maps, aerial photographs, lowest-level census tract data, and interviews with long-time local residents. However, specific release events and periods of interest should be identified prior to attempts to collect more specific demographic or land use information for actual dose reconstruction

  2. Phase reconstruction near to the two-dimensional ferromagnetic quantum critical point

    Science.gov (United States)

    Pedder, Chris; Karahasanovic, Una; Kruger, Frank; Green, Andrew

    2012-02-01

    We study the formation of new phases in two dimensions near to the putative quantum critical point of the itinerant ferromagnet to paramagnet phase transition. In addition to the first order and helimagnetic behaviour found in non-analytic extensions to Hertz-Millis theory [1] and in the quantum order-by-disorder approach [2], we find a small region of spin nematic order. Our approach also admits a concurrent formation of superconducting order. We further study the effect of small deformations from quadratic electron dispersion -- as previously found in three dimensions, these enlarge the region of spin nematic order at the expense of spiral order.[4pt] [1] D. Belitz, T.R. Kirkpatrick and T. Vojta, Rev. Mod. Phys. 77, 579 (2005),. V. Efremov, J.J. Betouras, A.V. Chubukov Phys. Rev. B 77, 220401(R), (2008)[0pt] [2] G. J. Conduit Phys. Rev. A 82, 043604 (2010)

  3. Optimization of Reconstructed Quality of Hard X-ray Phase Micro-Tomography

    OpenAIRE

    Liu, Huiqiang; Wu, Xizeng; Xiao, Tiqiao

    2015-01-01

    For the applications of hard X-ray Propagation-based Phase-contrast Computed micro-Tomography (PPCT) in high-resolution biological research, both the high spatial resolution and high contrast-to-noise ratio are simultaneously required for tiny structural discrimination and characterization. Most existing micro-CT techniques to improve image quality are limited by high cost, physical limitations, and complexity of the experimental hardware and setup. In this work a novel PPCT technique, which ...

  4. Numerical multiplexing and demultiplexing of digital holographic information for remote reconstruction in amplitude and phase.

    Science.gov (United States)

    Paturzo, M; Memmolo, P; Miccio, L; Finizio, A; Ferraro, P; Tulino, A; Javidi, B

    2008-11-15

    We investigate the possibility to multiplexing (Mux) and demultiplexing (de-Mux) numerically digital holograms (DHs) with the aim of optimizing their storage and/or transmission process. The DHs are multiplexed and demultiplexed thanks to the unique property of the digital holography to numerically manage the complex wavefields. We show that it is possible to retrieve correctly quantitative information about the amplitude and phase of one hundred DHs. This result can be useful to transmit efficiently, in terms of reduced amount of data, the DHs from the recording head to a remote display unit. PMID:19015690

  5. Validation of a raw data-based synchronization signal (kymogram) for phase-correlated cardiac image reconstruction

    Energy Technology Data Exchange (ETDEWEB)

    Ertel, Dirk; Kachelriess, Marc; Kalender, Willi A. [University of Erlangen-Nuernberg, Institute of Medical Physics (IMP), Erlangen (Germany); Pflederer, Tobias; Achenbach, Stephan [University of Erlangen-Nuernberg, Department of Internal Medicine II, Erlangen (Germany); Steffen, Peter [University of Erlangen-Nuernberg, Multimedia Communications and Signal Processing, Erlangen (Germany)

    2008-02-15

    Phase-correlated reconstruction is commonly used in computed tomography (CT)-based cardiac imaging. Alternatively to the commonly used ECG, the raw data-based kymogram function can be used as a synchronization signal. We used raw data of 100 consecutive patient exams to compare the performance of kymogram function to the ECG signal. For objective validation the correlation of the ECG and the kymogram was assessed. Additionally, we performed a double-blinded comparison of ECG-based and kymogram-based phase-correlated images. The two synchronization signals showed good correlation indicated by a mean difference in the detected heart rate of negligible 0.2 bpm. The mean image quality score was 2.0 points for kymogram-correlated images and 2.3 points for ECG-correlated images, respectively (3: best; 0: worst). The kymogram and the ECG provided images adequate for diagnosis for 93 and 97 patients, respectively. For 50% of the datasets the kymogram provided an equivalent or even higher image quality compared with the ECG signal. We conclude that an acceptable image quality can be assured in most cases by the kymogram. Improvements of image quality by the kymogram function were observed in a noticeable number of cases. The kymogram can serve as a backup solution when an ECG is not available or lacking in quality. (orig.)

  6. Reconstructing the geological history of the Egyptian Nile. Aswan - Kom Ombo phase

    International Nuclear Information System (INIS)

    Complete text of publication follows. The Nile is the longest river in the world, stretching north for approximately 4,000 miles from East Africa to the Mediterranean. Over the past several millions of years the Nile gradually has changed its location and size. Reconstructing the geological history of the Nile and identifying the location of abandoned and now buried paleo-channels and deltas, is an essential step in constructing a land use maps. An initial study area between Aswan and Kom Ombo, Egypt was selected for a geologic and geophysical field survey supported with interpretation of Landsat TM, ASTER and radar SIR-C/X-SAR images. Simultaneously, gravity and magnetotelluric data were acquired along two traverses; one following Wadi Abu Subbaira, east of the Nile while the other one across the Wadi Kubania pre-Nile drainage system, to the west. Gravity data were collected using a Scintrex CG-5 gravimeter and a differential GPS whereas the magnetotelluric data were collected using a controlled source audio magnetotelluric stratagem system. Integration of geologic field mapping, geophysical investigations, and interpretation of different types of remote sensing images were used to construct an improved geological and structural map of the study area. The constructed map reveals; 1- This area is strongly controlled by NE-SW, NW-SE and N-S trending basement structures, largely faults; 2- The evolution of these distinct fault sets was largely controlled by the Red Sea tectonics which started ∼22 Ma ago. Separation of the Arabian plate from the African plate provided NE-SW extension which subsequently resulted in the development of deep NW-SE grabens (e.g. the Kubania graben) where strain was closely localized because of the presence of older NW-SE trending Precambrian structures; 3-There is a prominent pre- Nile drainage system dominated by W- and NW- drainages emerging from the uplifted Red Sea Hills prior to opening of the Red Sea; 4- Wadi Abu Subbaira

  7. Performance enhancement of the single-phase series active filter by employing the load voltage waveform reconstruction and line current sampling delay reduction methods

    DEFF Research Database (Denmark)

    Senturk, O.S.; Hava, A.M.

    2011-01-01

    This paper proposes the waveform reconstruction method (WRM), which is utilized in the single-phase series active filter's (SAF's) control algorithm, in order to extract the load harmonic voltage component of voltage harmonic type single-phase diode rectifier loads. Employing WRM and the line...... current sampling delay reduction method, a single-phase SAF compensated system provides higher harmonic isolation performance and higher stability margins compared to the system using conventional synchronous-reference-frame-based methods. The analytical, simulation, and experimental studies of a 2.5 k......W single-phase SAF compensated system prove the theory....

  8. Oak Ridge Health Studies Phase 1 report, Volume 2: Part D, Dose Reconstruction Feasibility Study

    International Nuclear Information System (INIS)

    The purpose of Task 6 of Oak Ridge Phase I Health Studies is to provide summaries of current knowledge of toxic and hazardous properties of materials that are important for the Oak Ridge Reservation. The information gathered in the course of Task 6 investigations will support the task of focussing any future health studies efforts on those operations and emissions which have likely been most significant in terms of off-site health risk. The information gathered in Task 6 efforts will likely also be of value to individuals evaluating the feasibility of additional health,study efforts (such as epidemiological investigations) in the Oak Ridge area and as a resource for citizens seeking information on historical emissions

  9. Pyrotechnic shock response predictions combining statistical energy analysis and local random phase reconstruction

    Science.gov (United States)

    Bodin, E.; Brevart, B.; Wagstaff, P.; Borello, G.

    2002-07-01

    Numerous pyrotechnic devices are used on satellites to separate structural subsystems, deploy appendages, and activate on-board operating subsystems. The firing of these pyrotechnic mechanisms leads to severe impulsive loads which could sometimes lead to failures in electronic systems. The objective of the present investigation is to assess the relevance of a method combining deterministic calculations and statistical energy analysis to predict the time overall shock environment of electronic equipment components. The methods are applied to the low- and high-frequency ranges, respectively, which may be defined using a modal parameter based on the effective transmissibility. Initially, in order to address the problem of the low-frequency content of the mechanical shock pulse, the linear dynamic response of the equipment was calculated using direct time integration of a finite element model of the structure. The inputs in the form of the accelerations measured in all three directions at each of the four bolted interfaces were injected into the model. The high-frequency content of the shock response is taken into account by considering the intrinsic dynamic filtering of the equipment. This frequency filter magnitude is extrapolated from the transfer function given by statistical energy analysis between the different imposed accelerations and the response accelerations. Their associated phases are synthesized by considering pseudo-modal phase variations around the group velocity of the structural flexural waves. Combining the effects of the high-frequency filter outputs and the low-frequency finite element calculations yields good predictions of the equipment shock time response over the whole frequency range of interest. copyright 2002 Acoustical Society of America.

  10. Pyrotechnic shock response predictions combining statistical energy analysis and local random phase reconstruction.

    Science.gov (United States)

    Bodin, E; Brévart, B; Wagstaff, P; Borello, G

    2002-07-01

    Numerous pyrotechnic devices are used on satellites to separate structural subsystems, deploy appendages, and activate on-board operating subsystems. The firing of these pyrotechnic mechanisms leads to severe impulsive loads which could sometimes lead to failures in electronic systems. The objective of the present investigation is to assess the relevance of a method combining deterministic calculations and statistical energy analysis to predict the time overall shock environment of electronic equipment components. The methods are applied to the low- and high-frequency ranges, respectively, which may be defined using a modal parameter based on the effective transmissibility. Initially, in order to address the problem of the low-frequency content of the mechanical shock pulse, the linear dynamic response of the equipment was calculated using direct time integration of a finite element model of the structure. The inputs in the form of the accelerations measured in all three directions at each of the four bolted interfaces were injected into the model. The high-frequency content of the shock response is taken into account by considering the intrinsic dynamic filtering of the equipment. This frequency filter magnitude is extrapolated from the transfer function given by statistical energy analysis between the different imposed accelerations and the response accelerations. Their associated phases are synthesized by considering pseudo-modal phase variations around the group velocity of the structural flexural waves. Combining the effects of the high-frequency filter outputs and the low-frequency finite element calculations yields good predictions of the equipment shock time response over the whole frequency range of interest. PMID:12141340

  11. Qualitative phase space reconstruction analysis of supply-chain inventor time series

    Directory of Open Access Journals (Sweden)

    Jinliang Wu

    2010-10-01

    Full Text Available The economy systems are usually too complex to be analysed, but some advanced methods have been developed in order to do so, such as system dynamics modelling, multi-agent modelling, complex adaptive system modelling and qualitative modelling. In this paper, we considered a supply-chain (SC system including several kinds of products. Using historic suppliers’ demand data, we firstly applied the phase space analysis method and then used qualitative analysis to improve the complex system’s performance. Quantitative methods can forecast the quantitative SC demands, but they cannot indicate the qualitative aspects of SC, so when we apply quantitative methods to a SC system we get only numerous data of demand. By contrast, qualitative methods can show the qualitative change and trend of the SC demand. We therefore used qualitative methods to improve the quantitative forecasting results. Comparing the quantitative only method and the combined method used in this paper, we found that the combined method is far more accurate. Not only is the inventory cost lower, but the forecasting accuracy is also better.

  12. Exploring dynamic property of traffic flow time series in multi-states based on complex networks: Phase space reconstruction versus visibility graph

    Science.gov (United States)

    Tang, Jinjun; Liu, Fang; Zhang, Weibin; Zhang, Shen; Wang, Yinhai

    2016-05-01

    A new method based on complex network theory is proposed to analyze traffic flow time series in different states. We use the data collected from loop detectors on freeway to establish traffic flow model and classify the flow into three states based on K-means method. We then introduced two widely used methods to convert time series into networks: phase space reconstruction and visibility graph. Furthermore, in phase space reconstruction, we discuss how to determine delay time constant and embedding dimension and how to select optimal critical threshold in terms of cumulative degree distribution. In the visibility graph, we design a method to construct network from multi-variables time series based on logical OR. Finally, we study and compare the statistic features of the networks converted from original traffic time series in three states based on phase space and visibility by using the degree distribution, network structure, correlation of the cluster coefficient to betweenness and degree-degree correlation.

  13. A Two-Phase Space Resection Model for Accurate Topographic Reconstruction from Lunar Imagery with PushbroomScanners.

    Science.gov (United States)

    Xu, Xuemiao; Zhang, Huaidong; Han, Guoqiang; Kwan, Kin Chung; Pang, Wai-Man; Fang, Jiaming; Zhao, Gansen

    2016-01-01

    Exterior orientation parameters' (EOP) estimation using space resection plays an important role in topographic reconstruction for push broom scanners. However, existing models of space resection are highly sensitive to errors in data. Unfortunately, for lunar imagery, the altitude data at the ground control points (GCPs) for space resection are error-prone. Thus, existing models fail to produce reliable EOPs. Motivated by a finding that for push broom scanners, angular rotations of EOPs can be estimated independent of the altitude data and only involving the geographic data at the GCPs, which are already provided, hence, we divide the modeling of space resection into two phases. Firstly, we estimate the angular rotations based on the reliable geographic data using our proposed mathematical model. Then, with the accurate angular rotations, the collinear equations for space resection are simplified into a linear problem, and the global optimal solution for the spatial position of EOPs can always be achieved. Moreover, a certainty term is integrated to penalize the unreliable altitude data for increasing the error tolerance. Experimental results evidence that our model can obtain more accurate EOPs and topographic maps not only for the simulated data, but also for the real data from Chang'E-1, compared to the existing space resection model. PMID:27077855

  14. A Two-Phase Space Resection Model for Accurate Topographic Reconstruction from Lunar Imagery with PushbroomScanners

    Directory of Open Access Journals (Sweden)

    Xuemiao Xu

    2016-04-01

    Full Text Available Exterior orientation parameters’ (EOP estimation using space resection plays an important role in topographic reconstruction for push broom scanners. However, existing models of space resection are highly sensitive to errors in data. Unfortunately, for lunar imagery, the altitude data at the ground control points (GCPs for space resection are error-prone. Thus, existing models fail to produce reliable EOPs. Motivated by a finding that for push broom scanners, angular rotations of EOPs can be estimated independent of the altitude data and only involving the geographic data at the GCPs, which are already provided, hence, we divide the modeling of space resection into two phases. Firstly, we estimate the angular rotations based on the reliable geographic data using our proposed mathematical model. Then, with the accurate angular rotations, the collinear equations for space resection are simplified into a linear problem, and the global optimal solution for the spatial position of EOPs can always be achieved. Moreover, a certainty term is integrated to penalize the unreliable altitude data for increasing the error tolerance. Experimental results evidence that our model can obtain more accurate EOPs and topographic maps not only for the simulated data, but also for the real data from Chang’E-1, compared to the existing space resection model.

  15. Influence of heart rate on image quality of 64-slice spiral computed coronary angiography and optimization on reconstruction of phase window

    International Nuclear Information System (INIS)

    Objective: To evaluate the influence of heart rate on the image quality of 64-slice spiral computed coronary angiography (MSCTCA) and optimize the image reconstruction window. Methods: According to the heart rate, 86 patients were classified into 5 groups: group A, the heart rate ≤60 beat per minute(BMP); group B,61-70BMP, group C,71-80BMP, and group D>80BMP. The image quality of MSCTCA was scored 5 grades from 1-5 according to heart motion artifact. The influences of heart rate and reconstruction phase on the image quality of MSCTCA were evaluated. Results: Average heart rate was 64.4 ±10.1BMP. Diagnostic image quality (score>3) was attained in 277 of 344 segments at the best reconstruction interval. There was a significant corxelation between average heart rate and image quality, but there was no difference between relative delay (%) reconstruction and absolute delay (ms) reconstruction on the image quality. Conclusion: Reducing average heart rate is beneficial for improving the image quality. (authors)

  16. Automatic phase point determination of minimal motion reconstruction intervals with motion maps in ECG-gated CT diagnostics of coronary sclerosis

    International Nuclear Information System (INIS)

    Purpose: Cardio-CT motion maps for automated cardiac phase point determination were evaluated for image quality and reliability of coronary calcium scores. Materials and methods: 24 patients underwent ECG-gated non-enhanced cardiac CT for calcium scoring. From raw data the motion map software reconstructed low-resolution images in 2% steps of the RR interval and automatically generated cardiac motion maps for determination of minimal motion phase points. Diagnostic images were reconstructed in 10% steps of the RR interval (RR data) and according to the motion maps (MM data). For every data set, the Agatston score was calculated. Image quality was evaluated by two independent observers. Image quality was correlated with the Agatston score. Results: The Agatston score calculated over the RR interval showed a mean variation of 127 with 41% of patients assigned to more than one risk group. If the motion map RR intervals were calculated, only 16% patients were assigned to different risk categories with a mean variation of 55. Regarding the image quality, the inter-rater variance was moderate. The best image quality was achieved with the 30-40% and 70 - 80% RR interval. Over the complete RR interval motion map reconstructions produced a good image quality. Conclusion: Calculation of the Agatston score requires selection of the proper reconstruction interval to guarantee the assignment of patients into the appropriate risk category. By using motion maps for phase point determination, the amount of necessary reconstruction can be minimized and the assignment to different risk groups is also reduced. (orig.)

  17. Arsenic and Mercury Containing Traditional Chinese Medicine (Realgar and Cinnabar) Strongly Inhibit Organic Anion Transporters, Oat1 and Oat3, In Vivo in Mice

    Science.gov (United States)

    Yu, Wen-Hao; Zhang, Na; Qi, Jin-Feng; Sun, Chen; Wang, Yong-Hui; Lin, Mei

    2015-01-01

    Toxic heavy metals, including mercury (Hg) and arsenic (As), accumulate preferentially in kidneys and always cause acute renal failure. The aim of this study was to investigate whether these samples affect organic anion transporters, Oat1 and Oat3, in vivo in mice kidney. Mice (n = 10) were orally treated with investigational samples. After last administration, all mice were i.v. p-aminohippuric acid (PAH), and the blood and kidneys samples were collected. The concentrations of PAH were quantified by spectrophotometry. mRNA expressions of Oat1 and Oat3 were assayed by real-time PCR. In comparison with corresponding control, major pharmacokinetic parameters of PAH in sera were significantly changed by investigational samples (p Oat1 and Oat3 mRNA expression were significantly inhibited in investigational sample groups. Arsenic and mercury containing traditional Chinese medicine (Realgar and Cinnabar) probably induce kidney damage through inhibiting several members of the organic anion transporters (such as OAT1 and OAT3). PMID:26788513

  18. Reconstruction of electrical capacitance tomography images based on fast linearized alternating direction method of multipliers for two-phase flow system

    Institute of Scientific and Technical Information of China (English)

    Chongkun Xia; Chengli Su⁎; Jiangtao Cao; Ping Li

    2016-01-01

    Electrical capacitance tomography (ECT) has been applied to two-phase flow measurement in recent years. Image reconstruction algorithms play an important role in the successful applications of ECT. To solve the il-posed and nonlinear inverse problem of ECT image reconstruction, a new ECT image reconstruction method based on fast lin-earized alternating direction method of multipliers (FLADMM) is proposed in this paper. On the basis of theoretical analysis of compressed sensing (CS), the data acquisition of ECT is regarded as a linear measurement process of permittivity distribution signal of pipe section. A new measurement matrix is designed and L1 regularization method is used to convert ECT inverse problem to a convex relaxation problem which contains prior knowledge. A new fast alternating direction method of multipliers which contained linearized idea is employed to minimize the objective function. Simulation data and experimental results indicate that compared with other methods, the quality and speed of reconstructed images are markedly improved. Also, the dynamic experimental results in-dicate that the proposed algorithm can fulfil the real-time requirement of ECT systems in the application.

  19. Attenuation-based automatic kilovoltage selection and sonogram-affirmed iterative reconstruction: Effects on radiation exposure and image quality of portal-phase liver CT

    International Nuclear Information System (INIS)

    To compare the radiation dose and image quality between standard-dose CT and a low-dose CT obtained with the combined use of an attenuation-based automatic kilovoltage (kV) selection tool (CARE kV) and sonogram-affirmed iterative reconstruction (SAFIRE) for contrast-enhanced CT examination of the liver. We retrospectively reviewed 67 patients with chronic liver disease in whom both, standard-dose CT with 64-slice multidetector-row CT (MDCT) (protocol A), and low-dose CT with 128-slice MDCT using CARE kV and SAFIRE (protocol B) were performed. Images from protocol B during the portal phase were reconstructed using either filtered back projection or SAFIRE with 5 different iterative reconstruction (IR) strengths. We performed qualitative and quantitative analyses to select the appropriate IR strength. Reconstructed images were then qualitatively and quantitatively compared with protocol A images. Qualitative and quantitative analysis of protocol B demonstrated that SAFIRE level 2 (S2) was most appropriate in our study. Qualitative and quantitative analysis comparing S2 images from protocol B with images from protocol A, showed overall good diagnostic confidence of S2 images despite a significant radiation dose reduction (47% dose reduction, p < 0.001). Combined use of CARE kV and SAFIRE allowed significant reduction in radiation exposure while maintaining image quality in contrast-enhanced liver CT.

  20. A phase field approach with a reaction pathways-based potential to model reconstructive martensitic transformations with a large number of variants

    Science.gov (United States)

    Denoual, C.; Vattré, A.

    2016-05-01

    A pathway tree is constructed by recursively duplicating a single reconstructive martensitic transformation path with respect to lattice symmetries and point-group rotations. An energy potential built on this pathway is implemented in a phase-field technique in large strain framework, with the transformational strain as the order parameter. A specific splitting between non-dissipative elastic behavior and the dissipative evolution of the order parameter allows for the modeling of acoustic waves during rapid transformations. A simple toy-model transition from hexa- to square-lattice successfully demonstrates the possibility to model reconstructive martensitic transformations for a large number of variants (more than one hundred). Pure traction applied to our toy-model shows that variants can nucleate into previously created variants, with a hierarchical nucleation of variants spanning over five levels of transformation.

  1. A Discrete Phase-Space Calculus for Quantum Spins based on a Reconstruction Method using Coherent States

    OpenAIRE

    Weigert, Stefan

    1999-01-01

    To reconstruct a mixed or pure quantum state of a spin s is possible through coherent states: its density matrix is fixed by the probabilities to measure the value s along 4s(s+1) appropriately chosen directions in space. Thus, after inverting the experimental data, the statistical operator is parametrized entirely by expectation values. On this basis, a symbolic calculus for quantum spins is developed, the `expectation-value representation.' It resembles the Moyal representation for SU(2) bu...

  2. A Preliminary Study on the Reconstruction Algorithm of the Bubble Size to Inspect Two-phase Flows Using Single Cone-beam X-ray

    Energy Technology Data Exchange (ETDEWEB)

    Yim, Che Wook; Kim, Song Hyun; Shin, Chang Ho [Hanyang University, Seoul (Korea, Republic of)

    2015-05-15

    In two-phase flow, the motions of dispersed bubbles influence fluid properties such as heat transfer. In order to analyze how the bubble motion affects the fluid property, various techniques have been developed. An optical method has been used for the analysis of the single-phase flow such as Liquid Doppler Velocimetry (LDV) and Particle Image Velocimetry (PIV). However, it has some significant application problems which cannot be used for the opaque fluid and two phase flows. Phase-Doppler Method, another optical method, can be applied to the two-phase flow analysis. It is noted that the method also has difficulty to analyze the opaque flows. In a previous study, x-ray PIV method was proposed as the technique to measure the flow velocity and to get the flow vector field. However, there is no appropriate approach to analyze the bubble size for the two phase flows. In this study, a technique to estimate the bubble size by using x-ray is proposed as a preliminary study to develop an algorithm of the two phase flow analysis. In this study, a reconstruction algorithm of bubble size in two-phase flows using single x-ray was proposed. The analysis shows that 3-dimensional bubble size can be estimated by the multichannel detectors with the detection information. Also, a preliminary study on multi-bubble cases was performed. The analysis of the results show that that multiple bubbles can be separated by using the property that is the symmetry of bubbles. This proposed algorithm can detect the bubbles in flow of opaque fluids or nontransparent pipes which cannot be analyzed by optical methods. It is expected that the proposed method can utilized to inspect the bubbles in two-phase bubbly flow.

  3. High-Performance Harmonic Isolation and Load Voltage Regulation of the Three-Phase Series Active Filter Utilizing the Waveform Reconstruction Method

    DEFF Research Database (Denmark)

    Senturk, Osman Selcuk; Hava, Ahmet M.

    2009-01-01

    This paper develops a waveform reconstruction method (WRM) for high accuracy and bandwidth signal decomposition of voltage-harmonic-type three-phase diode rectifier load voltage into its harmonic and fundamental components, which are utilized in the series active filter (SAF) control algorithms....... The SAF-compensated system utilizing WRM provides highperformance load harmonic voltage isolation and load voltage regulation at steady-state and during transients compared to the system utilizing the synchronous reference-frame-based signal decomposition. In addition, reducing the line current...... sampling delay in the discrete-time implementation enhances the stability of the SAF. The simulations and experimental studies of a 10-kW three-phase SAF-compensated system prove the theory....

  4. Optimisation of image reconstruction for phase-contrast x-ray Talbot–Lau imaging with regard to mechanical robustness

    Science.gov (United States)

    Seifert, M.; Kaeppler, S.; Hauke, C.; Horn, F.; Pelzer, G.; Rieger, J.; Michel, T.; Riess, C.; Anton, G.

    2016-09-01

    X-ray grating-based phase-contrast imaging opens new opportunities, inter alia, in medical imaging and non-destructive testing. Because, information about the attenuation properties and about the refractive properties of an object are gained simultaneously. Talbot–Lau imaging requires the knowledge of a reference or free-field image. The long-term stability of a Talbot–Lau interferometer is related to the time span of the validity of a measured reference image. It would be desirable to keep the validity of the reference image for a day or longer to improve feasibility of Talbot–Lau imaging. However, for example thermal and other long-term external influences result in drifting effects of the phase images. Therefore, phases are shifting over time and the reference image is not valid for long-term measurements. Thus, artifacts occur in differential phase-contrast images. We developed an algorithm to determine the differential phase-contrast image with the help of just one calibration image, which is valid for a long time-period. With the help of this algorithm, called phase-plane-fit method, it is possible to save measurement-time, as it is not necessary to take a reference image for each measurement. Additionally, transferring the interferometer technique from laboratory setups to conventional imaging systems the necessary rigidity of the system is difficult to achieve. Therefore, short-term effects like vibrations or distortions of the system lead to imperfections within the phase-stepping procedure. Consequently, artifacts occur in all three image modalities (differential phase-contrast image, attenuation image and dark-field image) of Talbot–Lau imaging. This is a problem with regard to the intended use of phase-contrast imaging for example in clinical routine or non-destructive testing. In this publication an algorithm of Vargas et al is applied and complemented to correct inaccurate phase-step positions with the help of a principal component analysis

  5. Benchmark calculations of power distribution within fuel assemblies. Phase 2: comparison of data reduction and power reconstruction methods in production codes

    International Nuclear Information System (INIS)

    Systems loaded with plutonium in the form of mixed-oxide (MOX) fuel show somewhat different neutronic characteristics compared with those using conventional uranium fuels. In order to maintain adequate safety standards, it is essential to accurately predict the characteristics of MOX-fuelled systems and to further validate both the nuclear data and the computation methods used. A computation benchmark on power distribution within fuel assemblies to compare different techniques used in production codes for fine flux prediction in systems partially loaded with MOX fuel was carried out at an international level. It addressed first the numerical schemes for pin power reconstruction, then investigated the global performance including cross-section data reduction methods. This report provides the detailed results of this second phase of the benchmark. The analysis of the results revealed that basic data still need to be improved, primarily for higher plutonium isotopes and minor actinides. (author)

  6. A dictionary learning approach with overlap for the low dose computed tomography reconstruction and its vectorial application to differential phase tomography.

    Directory of Open Access Journals (Sweden)

    Alessandro Mirone

    Full Text Available X-ray based Phase-Contrast Imaging (PCI techniques have been demonstrated to enhance the visualization of soft tissues in comparison to conventional imaging methods. Nevertheless the delivered dose as reported in the literature of biomedical PCI applications often equals or exceeds the limits prescribed in clinical diagnostics. The optimization of new computed tomography strategies which include the development and implementation of advanced image reconstruction procedures is thus a key aspect. In this scenario, we implemented a dictionary learning method with a new form of convex functional. This functional contains in addition to the usual sparsity inducing and fidelity terms, a new term which forces similarity between overlapping patches in the superimposed regions. The functional depends on two free regularization parameters: a coefficient multiplying the sparsity-inducing L1 norm of the patch basis functions coefficients, and a coefficient multiplying the L2 norm of the differences between patches in the overlapping regions. The solution is found by applying the iterative proximal gradient descent method with FISTA acceleration. The gradient is computed by calculating projection of the solution and its error backprojection at each iterative step. We study the quality of the solution, as a function of the regularization parameters and noise, on synthetic data for which the solution is a-priori known. We apply the method on experimental data in the case of Differential Phase Tomography. For this case we use an original approach which consists in using vectorial patches, each patch having two components: one per each gradient component. The resulting algorithm, implemented in the European Synchrotron Radiation Facility tomography reconstruction code PyHST, has proven to be efficient and well-adapted to strongly reduce the required dose and the number of projections in medical tomography.

  7. Optimization of genetic algorithm for reconstruction of cross-phase modulation frequency-resolved optical gating data

    Czech Academy of Sciences Publication Activity Database

    Vraný, Boleslav; Honzátko, Pavel; Kaňka, Jiří

    2011-01-01

    Roč. 24, č. 5 (2011), 448-456. ISSN 0894-3370 R&D Projects: GA MŠk OE08021 Institutional research plan: CEZ:AV0Z20670512 Keywords : frequency resolved optical gating, FROG * amplitude and phase retrieval * genetic algorithm, GA Subject RIV: BH - Optics, Masers, Lasers Impact factor: 0.600, year: 2011

  8. 76 FR 9786 - NIOSH Dose Reconstruction Program Ten-Year Review-Phase I Report on Customer Service; Request for...

    Science.gov (United States)

    2011-02-22

    ... Review--Phase I Report on Customer Service; Request for Public Review and Comment AGENCY: National... Report on Customer Service.'' This publication is part of a review by NIOSH of its program in support of... customer service provided by NIOSH in the program. The document can be found at...

  9. Optimization of reconstruction algorithm for cross-phase modulation frequency-resolve optical gating in a high birefringence microstructured fiber

    Czech Academy of Sciences Publication Activity Database

    Vraný, Boleslav; Honzátko, Pavel; Kaňka, Jiří

    Praha : Agentura Action M, 2005. s. 137. ISBN 80-86742-08-3. [Photonics Prague 2005. International Conference on Photonics, Devices and Systems /5./. 08.06.2005-11.06.2005, Prague] R&D Projects: GA ČR(CZ) GA102/05/0995 Institutional research plan: CEZ:AV0Z20670512 Keywords : laser variables measurement * genetic algorithms * phase measurement Subject RIV: BH - Optics, Masers, Lasers

  10. Optimization of reconstruction algorithm for cross-phase modulation frequency-resolve optical gating in a high birefringence microstructured fiber

    Czech Academy of Sciences Publication Activity Database

    Vraný, Boleslav; Honzátko, Pavel; Kaňka, Jiří

    Pilsen : University of West Bohemia, 2005 - (Pinker, J.), s. 357-360 ISBN 80-7043-369-8. [Applied Electronics 2005 [0054019] [0054053]. Pilsen (CZ), 07.09.2005-08.09.2005] R&D Projects: GA ČR(CZ) GA102/05/0995 Institutional research plan: CEZ:AV0Z20670512 Keywords : laser variables measurement * genetic algorithms * phase measurement Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  11. First-principles study of structural and electronic properties of different phases of GaAs

    Energy Technology Data Exchange (ETDEWEB)

    Arabi, H. [Faculty of Science, Department of Physics, University of Birjand, Birjand (Iran, Islamic Republic of)]. E-mail: harabi@birjand.ac.ir; Pourghazi, A. [Faculty of Science, Department of Physics, University of Isfahan, Isfahan (Iran, Islamic Republic of); Ahmadian, F. [Faculty of Science, Department of Physics, University of Birjand, Birjand (Iran, Islamic Republic of); Nourbakhsh, Z. [Faculty of Science, Department of Physics, University of Isfahan, Isfahan (Iran, Islamic Republic of)

    2006-03-01

    We present a theoretical investigation of structural and electronic properties of the four known structural phases of GaAs (zinc-blende, sc16, cinnabar and Cmcm). We used the full potential linearized augmented plane wave method, within local density approximation, and also within generalized gradient approximation for the exchange correlation potential. The lattice constants, bulk modulus and its pressure derivative are calculated for each of the four phases. The data obtained for the transition pressures between different phases are presented. Band structures and densities of states of the four phases are also given. The results are compared with previous calculations and with experimental results.

  12. Optimization of reconstruction algorithm for cross-phase modulation frequency-resolve optical gating in a high birefringence microstructured fiber

    Czech Academy of Sciences Publication Activity Database

    Vraný, Boleslav; Honzátko, Pavel; Kaňka, Jiří

    Bellingham : SPIE The International Society for Optical Engineering, 2006 - (Tománek, P.; Hrabovský, M.; Miler, M.; Senderáková, D.), pp.618012.1-618012.6 ISBN 0-8194-6236-5. ISSN 0277-786X. - (Proceedings of SPIE. 6180). [Photonics Prague 2005. International Conference on Photonics, Devices and Systems /5./. Prague (CZ), 08.06.2005-11.06.2005] R&D Projects: GA ČR(CZ) GA102/05/0995 Institutional research plan: CEZ:AV0Z2067918 Keywords : laser variables measurement * genetic algorithms * phase measurement Subject RIV: BH - Optics, Masers, Lasers

  13. 相空间重构在引信信号检测中的应用%Application of Phase-space Reconstruction Technology to Fuze Signal Detection

    Institute of Scientific and Technical Information of China (English)

    薛永先; 袁运生; 杨永赤; 张良伟; 张元军

    2009-01-01

    With the continuous development of technology of low-level/hedgehopping attack weapons, air-de-fense missile fuze is facing more and more strong ground and sea clutter interference. It is very difficult for con-ventional signal detection which is based on the statistical theory to detect weak target signal from the strong clutter/sea interference. According to theory of phase-space reconstruction,a modeling and forecasting technique based on neural network for chaotic time series is proposed. The application of phase-space reconstruction tech-nology to fuze signal detection is investigated. Theoretical analysis and real data simulation show that this meth-od which does not need a statistical model is applicable to air-defense missile fuze system; it can effectively im-prove the ability of weak signal detection,providing a new method for the weak signal detection under the strong clutter environment.%随着低空超低空突袭兵器技术的不断发展,防空导弹引信面临着越来越强的地海杂波的干扰.基于统计理论的传统信号检测很难从强地海杂波中把微弱目标信号检测出来.以相空间重构理论为基础,提出了基于神经网络的混沌时间序列建模与预测方法,探讨了相空间重构技术在引信信号检测中的应用.通过理论分析和实测杂波数据仿真,表明了该方法不需建立统计模型.适合在防空导弹引信系统中应用,能够有效地提高引信检测微弱信号的能力,为强杂波环境下的微弱信号检测提供了一个新方法.

  14. Reconstruction of settlement phases at Intermediate Bronze Age structures in the Negev Highlands (Israel) using luminescence dating

    Science.gov (United States)

    Junge, Andrea; Lomax, Johanna; Shahack-Gross, Ruth; Dunseth, Zachary C.; Finkelstein, Israel; Fuchs, Markus

    2016-04-01

    OSL dating is usually applied to sediments in paleoenvironmental sciences. However, there is only limited experience with determining the age of archaeological stone structures by OSL using dust deposits associated with these structures. The age of trapped dust deposits may be used to date the onset of settlement (sediment below structures), settlement activity (occupation layer), or the time after settlement (sediment between collapsed walls and roofs). In this study, OSL dating is applied for establishing a chronology of settlement structures situated in the Negev Highlands, Israel. Two archaeological sites are investigated to identify the occupation history, by dating the aeolian dust trapped within the remains of ancient buildings. OSL dating techniques are applied using coarse grain quartz and a standard SAR protocol. First results indicate that the luminescence properties of the trapped sediments are suitable for OSL dating. Therefore, it was possible to date the onset of sedimentation in a later phase of the human occupation or shortly after the settlement was abandoned, which is supported by archaeological evidence gained from pottery finds and the architecture of the buildings.

  15. Penile reconstruction

    OpenAIRE

    Garaffa, Giulio; Sansalone, Salvatore; Ralph, David J.

    2012-01-01

    During the most recent years, a variety of new techniques of penile reconstruction have been described in the literature. This paper focuses on the most recent advances in male genital reconstruction after trauma, excision of benign and malignant disease, in gender reassignment surgery and aphallia with emphasis on surgical technique, cosmetic and functional outcome.

  16. Penile reconstruction

    Institute of Scientific and Technical Information of China (English)

    Giulio Garaffa; Salvatore Sansalone; David J Ralph

    2013-01-01

    During the most recent years,a variety of new techniques of penile reconstruction have been described in the literature.This paper focuses on the most recent advances in male genital reconstruction after trauma,excision of benign and malignant disease,in gender reassignment surgery and aphallia with emphasis on surgical technique,cosmetic and functional outcome.

  17. Measurements of b → u amplitude and CKM weak phase γ using B0 → D0K*0 decays reconstructed with the BABAR detector

    International Nuclear Information System (INIS)

    In this thesis we present CP violation studies in the B mesons system, and in particular measurements of the angle γ of the Unitarity Triangle, using data collected by the BABAR experiment. The angle γ is the relative weak phase between the Vub and Vcb elements of the CKM matrix. A crucial parameter, which drives the sensitivity to γ, is the ratio r between b → u and b → c transition amplitudes. In the first part of the thesis, general issues on γ studies and the status of the present measurements are introduced. The experimental work is then detailed. It is composed of two different analyses of B0 → D0(D-bar0)K*0. In the first analysis, these decays are studied through the ADS method, where the neutral D mesons are reconstructed into K±π±, K±π±π0 and K±π±π±π± final states. This analysis allows us to determine, for the first time, the ratio r for B0 → D0(D-bar0)K*0, which is found to be r equals (0.260 +0.077 -0.088). The large value for the parameter r makes the use of this channel interesting for present and future facilities, for the determination of γ. In the second analysis, the channel B0 → D0(D-bar0)K*0 is studied with a Dalitz method and the neutral D mesons are reconstructed into KSπ+π- final states. The determination of γ from this analysis is γ equals (162 ± 56) degrees, with a 180 degrees ambiguity. The result for r from the combination of the two analyses is: r equals (0.259 +0.073 -0.079). These results represent the first constraints on γ and r obtained from neutral B decays. Finally, data driven simulation studies are discussed, which show that the study of the B0 → D0(D-bar0)K*0 is competitive, for the determination of γ, with the other analysis aiming to extract γ from charged B decays. (author)

  18. Climate Reconstructions

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA Paleoclimatology Program archives reconstructions of past climatic conditions derived from paleoclimate proxies, in addition to the Program's large...

  19. Laryngopharyngeal reconstruction

    OpenAIRE

    Kazi, Rehan A

    2006-01-01

    There is a high incidence of hypopharyngeal cancer is our country due to the habits of tobacco and alcohol. Moreover these cases are often detected in the late stages thereby making the issue of reconstruction very tedious and unpredictable. There are a number of options for laryngopharyngeal reconstruction available now including the use of microvascular flaps depending upon the patient’s fitness, motivation, technical expertise, size and extent of the defect. This article reviews the differ...

  20. The art of reconstruction

    OpenAIRE

    Healey, Michael; Esson, Michael

    2011-01-01

    The ‘Art of Reconstruction Research Project’ is where re-skilling of plastic surgeons by artists is already in an embryonic phase. In integrating the required network of associated skills, expertise and experience, the research collaboration brings together artists within The Drawing Research Group of The Faculty of Art, Architecture and Design (AAD) and the distinguished work of Professor Mike Esson, Director, The International Drawing Research Institute (IDRI). Th...

  1. Project Reconstruct.

    Science.gov (United States)

    Helisek, Harriet; Pratt, Donald

    1994-01-01

    Presents a project in which students monitor their use of trash, input and analyze information via a database and computerized graphs, and "reconstruct" extinct or endangered animals from recyclable materials. The activity was done with second-grade students over a period of three to four weeks. (PR)

  2. Vaginal reconstruction

    Energy Technology Data Exchange (ETDEWEB)

    Lesavoy, M.A.

    1985-05-01

    Vaginal reconstruction can be an uncomplicated and straightforward procedure when attention to detail is maintained. The Abbe-McIndoe procedure of lining the neovaginal canal with split-thickness skin grafts has become standard. The use of the inflatable Heyer-Schulte vaginal stent provides comfort to the patient and ease to the surgeon in maintaining approximation of the skin graft. For large vaginal and perineal defects, myocutaneous flaps such as the gracilis island have been extremely useful for correction of radiation-damaged tissue of the perineum or for the reconstruction of large ablative defects. Minimal morbidity and scarring ensue because the donor site can be closed primarily. With all vaginal reconstruction, a compliant patient is a necessity. The patient must wear a vaginal obturator for a minimum of 3 to 6 months postoperatively and is encouraged to use intercourse as an excellent obturator. In general, vaginal reconstruction can be an extremely gratifying procedure for both the functional and emotional well-being of patients.

  3. Vaginal reconstruction

    International Nuclear Information System (INIS)

    Vaginal reconstruction can be an uncomplicated and straightforward procedure when attention to detail is maintained. The Abbe-McIndoe procedure of lining the neovaginal canal with split-thickness skin grafts has become standard. The use of the inflatable Heyer-Schulte vaginal stent provides comfort to the patient and ease to the surgeon in maintaining approximation of the skin graft. For large vaginal and perineal defects, myocutaneous flaps such as the gracilis island have been extremely useful for correction of radiation-damaged tissue of the perineum or for the reconstruction of large ablative defects. Minimal morbidity and scarring ensue because the donor site can be closed primarily. With all vaginal reconstruction, a compliant patient is a necessity. The patient must wear a vaginal obturator for a minimum of 3 to 6 months postoperatively and is encouraged to use intercourse as an excellent obturator. In general, vaginal reconstruction can be an extremely gratifying procedure for both the functional and emotional well-being of patients

  4. ACL reconstruction - discharge

    Science.gov (United States)

    Anterior cruciate ligament reconstruction - discharge; ACL reconstruction - discharge ... had surgery to reconstruct your anterior cruciate ligament (ACL). The surgeon drilled holes in the bones of ...

  5. Radio Reconstructions

    OpenAIRE

    Bulley, James; Jones, Daniel

    2013-01-01

    Radio Reconstructions is a sound installation which use indeterminate radio broadcasts as its raw material. Each piece is structured by a notated score, which controls its rhythm, dynamics and melodic contour over time. The audio elements used to enact this score are selected in real-time from unknown radio transmissions, by an autonomous software system which is continuously scanning the radio waves in search of similar fragments of audio. Using a technique known as audio mosaicing, hund...

  6. High speed 3-D Surface Profilometry Employing Trapezoidal HSI Phase Shifting Method with Multi-band Calibration for Colour Surface Reconstruction

    CERN Document Server

    Chen, L C; Shu, Y S

    2010-01-01

    This article presents a new optical measurement method employing a HSI (Hue, Saturation and Intensity) colour model to form trapezoidal structured patterns for morphology reconstruction of a measured object at a high speed. Profilometry on objects having non-monochromatic surfaces is considered as one of the remaining most challenges faced by the currently existing structured-light projection methods since the surface reflectivity to red, green and blue light may vary significantly. To address this, an innovative colour calibration method for hue component is developed to determine the accurate reflectivity response of the measured surface. The trapezoidal colour pattern is calibrated to compensate the hue-shifted quantity induced by the reflective characteristics of the object's surface. The developed method can reconstruct precise 3-D surface models from objects by acquiring a single-shot image, which can achieve high-speed profilometry and avoid in-situ potential measurement disturbances such as environmen...

  7. Tracheal reconstructions.

    Science.gov (United States)

    Srikrishna, S V; Shekar, P S; Shetty, N

    1998-12-01

    Surgical reconstruction of the trachea is a relatively complex procedure. We had 20 cases of tracheal stenosis. We have a modest experience of 16 tracheal reconstructions for acquired tracheal stenosis. Two patients underwent laser treatment while another two died before any intervention. The majority of these cases were a result of prolonged ventilation (14 cases), following organophosphorous poisoning (11 cases), Guillain-Barré syndrome, bullet injury, fat embolism and surprisingly only one tumor, a case of mucoepidermoid carcinoma, who had a very unusual presentation. There were 12 males and 4 females in this series, age ranging from 12-35 years. The duration of ventilation ranged from 1-21 days and the interval from decannulation to development of stridor was between 5-34 days. Six of them were approached by the cervical route, 5 by thoracotomy and cervical approach, 2 via median sternotomy and 3 by thoracotomy alone. Five of them required an additional laryngeal drop and 1 required pericardiotomy and release of pulmonary veins to gain additional length. The excised segments of trachea measured 3 to 5 cms in length. All were end to end anastomosis with interrupted Vicryl sutures. We have had no experience with stents or prosthetic tubes. Three patients developed anastomotic leaks which were controlled conservatively. Almost all of them required postoperative tracheo-bronchial suctioning with fibreoptic bronchoscope. We had one death in this series due to sepsis. PMID:9914459

  8. Sparse Projection Angle Phase Contrast CT Image Reconstruction Based on Refractive Angle%基于折射角的稀疏投影角度相衬CT图像重建

    Institute of Scientific and Technical Information of China (English)

    司凯; 孙丰荣; 宋尚玲; 秦峰

    2015-01-01

    已有基于X射线吸收衬度机制的计算机断层成像( CT)技术很难对由轻元素构成的弱吸收物质进行高质量成像。 X射线相位衬度CT成像是对弱吸收物质具有超高分辨率的一种CT技术,但该技术成像时间长、所需X射线辐射剂量大,不利于临床推广应用,因此,研究稀疏投影角度条件下的X射线相位衬度CT图像重建问题,基于压缩感知图像重建理论,使用折射角信息减少X射线辐射剂量,提出一种X射线相位衬度CT图像重建算法。实验结果表明,与滤波反投影算法相比,该算法在稀疏投影角度下可以得到较高质量的重建图像,在实际数据实验中能获得较高的峰值信噪比和数值准确性。%It is not easy for conventional X-ray absorption contrast based Computed Tomography ( CT ) imaging technique to get a high quality image from the weak absorption materials comprising of light elements. X-ray phase contrast CT imaging is a CT imaging technique aiming at weak absorption materials and possessing ultrahigh resolution. However,X-ray phase contrast CT imaging takes too long time and requires too high X-ray radiation dose,which can set back the promotion of clinical applications. So it has significant meaning to study the image reconstruction for phase contrast CT using few projection views. This paper is under the theory of Compressed Sensing( CS) ,uses refractive angle information,aims to reduce the X-ray radiation dose,proposes a X-ray phase contrast CT image reconstruction algorithm. Experimental results show that compared with Filtered Back-projection ( FBP ) algorithm, this algorithm can use few projection views to obtain reconstructed images of higher quality,and can get higher Peak Signal to Noise Ratio( PSNR) and numerical accuracy in the actual data experiment.

  9. High-speed 3D surface profilometry employing trapezoidal phase-shifting method with multi-band calibration for colour surface reconstruction

    International Nuclear Information System (INIS)

    This paper presents a new optical measurement method employing a HSI (hue, saturation and intensity) colour model to form trapezoidal structured patterns for morphology reconstruction of a measured object at high speed. Profilometry on objects having non-monochromatic surfaces is considered as one of the remaining challenges most faced by the currently existing structured-light projection methods since the surface reflectivity to red, green and blue light may vary significantly. To address this, an innovative colour calibration method for a hue component is developed to determine the accurate reflectivity response of the measured surface. The trapezoidal colour pattern is calibrated to compensate the hue-shifted quantity induced by the reflective characteristics of the object's surface. The developed method can reconstruct precise 3D surface models from objects by acquiring a single-shot image, which can achieve high-speed profilometry and avoid in situ potential measurement disturbances such as environmental vibration. To verify the feasibility of the developed methodology, some experiments were conducted to confirm that the measurement accuracy can be controlled within 2.5% of the overall measurement range and the repeatability of 3.0% within ±3σ can be achieved

  10. Structural phase transition and spontaneous interface reconstruction in La2/3Ca1/3MnO3/BaTiO3 superlattices

    Science.gov (United States)

    Turner, S.; Lebedev, O. I.; Verbeeck, J.; Gehrke, K.; Moshnyaga, V.; Van Tendeloo, G.

    2013-01-01

    (La2/3Ca1/3MnO3)n/(BaTiO3)m (LCMOn/BTOm) superlattices on MgO and SrTiO3 substrates with different layer thicknesses (n = 10, 38, 40 and m = 5, 18, 20) have been grown by metal organic aerosol deposition (MAD) and have been fully characterized down to the atomic scale to study the interface characteristics. Scanning transmission electron microscopy combined with spatially resolved electron energy-loss spectroscopy provides clear evidence for the existence of atomically sharp interfaces in MAD grown films, which exhibit epitaxial growth conditions, a uniform normal strain, and a fully oxidized state. Below a critical layer thickness the LCMO structure is found to change from the bulk Pnma symmetry to a pseudocubic R3¯c symmetry. An atomically flat interface reconstruction consisting of a single Ca-rich atomic layer is observed on the compressively strained BTO on LCMO interface, which is thought to partially neutralize the total charge from the alternating polar atomic layers in LCMO as well as relieving strain at the interface. No interface reconstruction is observed at the tensile strained LCMO on BTO interface.

  11. LOFAR sparse image reconstruction

    Science.gov (United States)

    Garsden, H.; Girard, J. N.; Starck, J. L.; Corbel, S.; Tasse, C.; Woiselle, A.; McKean, J. P.; van Amesfoort, A. S.; Anderson, J.; Avruch, I. M.; Beck, R.; Bentum, M. J.; Best, P.; Breitling, F.; Broderick, J.; Brüggen, M.; Butcher, H. R.; Ciardi, B.; de Gasperin, F.; de Geus, E.; de Vos, M.; Duscha, S.; Eislöffel, J.; Engels, D.; Falcke, H.; Fallows, R. A.; Fender, R.; Ferrari, C.; Frieswijk, W.; Garrett, M. A.; Grießmeier, J.; Gunst, A. W.; Hassall, T. E.; Heald, G.; Hoeft, M.; Hörandel, J.; van der Horst, A.; Juette, E.; Karastergiou, A.; Kondratiev, V. I.; Kramer, M.; Kuniyoshi, M.; Kuper, G.; Mann, G.; Markoff, S.; McFadden, R.; McKay-Bukowski, D.; Mulcahy, D. D.; Munk, H.; Norden, M. J.; Orru, E.; Paas, H.; Pandey-Pommier, M.; Pandey, V. N.; Pietka, G.; Pizzo, R.; Polatidis, A. G.; Renting, A.; Röttgering, H.; Rowlinson, A.; Schwarz, D.; Sluman, J.; Smirnov, O.; Stappers, B. W.; Steinmetz, M.; Stewart, A.; Swinbank, J.; Tagger, M.; Tang, Y.; Tasse, C.; Thoudam, S.; Toribio, C.; Vermeulen, R.; Vocks, C.; van Weeren, R. J.; Wijnholds, S. J.; Wise, M. W.; Wucknitz, O.; Yatawatta, S.; Zarka, P.; Zensus, A.

    2015-03-01

    Context. The LOw Frequency ARray (LOFAR) radio telescope is a giant digital phased array interferometer with multiple antennas distributed in Europe. It provides discrete sets of Fourier components of the sky brightness. Recovering the original brightness distribution with aperture synthesis forms an inverse problem that can be solved by various deconvolution and minimization methods. Aims: Recent papers have established a clear link between the discrete nature of radio interferometry measurement and the "compressed sensing" (CS) theory, which supports sparse reconstruction methods to form an image from the measured visibilities. Empowered by proximal theory, CS offers a sound framework for efficient global minimization and sparse data representation using fast algorithms. Combined with instrumental direction-dependent effects (DDE) in the scope of a real instrument, we developed and validated a new method based on this framework. Methods: We implemented a sparse reconstruction method in the standard LOFAR imaging tool and compared the photometric and resolution performance of this new imager with that of CLEAN-based methods (CLEAN and MS-CLEAN) with simulated and real LOFAR data. Results: We show that i) sparse reconstruction performs as well as CLEAN in recovering the flux of point sources; ii) performs much better on extended objects (the root mean square error is reduced by a factor of up to 10); and iii) provides a solution with an effective angular resolution 2-3 times better than the CLEAN images. Conclusions: Sparse recovery gives a correct photometry on high dynamic and wide-field images and improved realistic structures of extended sources (of simulated and real LOFAR datasets). This sparse reconstruction method is compatible with modern interferometric imagers that handle DDE corrections (A- and W-projections) required for current and future instruments such as LOFAR and SKA.

  12. Breast Reconstruction and Prosthesis

    Science.gov (United States)

    ... have breast reconstruction If you choose to have reconstructive surgery, follow these steps: STEP 1 — Ask your doctor to refer you to a plastic surgeon who is an expert in breast reconstruction. ...

  13. 朱砂灌胃给药后汞在孕大鼠脏器内的分布和排泄途径研究%Study on Distribution in Organs and Excretion Pathway of Mercury in Pregnant Rats after Administration of Cinnabar

    Institute of Scientific and Technical Information of China (English)

    汤家铭; 米金霞; 吴文斌; 谷颖敏; 李咏梅; 夏晶; 张甦; 曹帅; 季申

    2011-01-01

    Objective: To study the distribution and excretion pathway of mercury in pregnant rats after administration of cinnabar. Methods; Compared with the reproductive toxicity test, the female SD rats after mating were randomly divided into high (1 000 mg/kg) , medium (300 mg/kg) , and low-dose (100 mg/kg) cinnabar groups, and negative control group (0.5% CMC-Na) , with ten rats in each group. The rats in different dose cinnabar groups were administered intragastrically with cinnabar from the sixth day to the fifteenth day after pregnancy, and all the rats were sacrificed on the twentieth day of pregnancy. The main organs (including heart, liver, spleen, lung, kidney, brain and uterus) , blood, placentae, fetuses and urine of the pregnant rats were obtained to detect the mercury concentration by inductively coupled plasma mass spectrometry ( ICP-MS) ; the feces were taken at different time points to determine the mercury concentration by inductively coupled plasma optical emission spectrometer (ICP-OES) ; the distribution in different organs and the excretion pathway of mercury were analyzed. Results: The mercury concentrations of the heart, liver, kidney and uterus of the rats in different dose cinnabar groups were higher than those of the rats in negative control group, and the concentration increased with the enhanced dose; there was no statistical difference on the mercury concentrations of the brain, placentae and fetuses between different dose cinnabar groups and negative control group. There were large amount of mercury in the feces on the second day after administration, and the mercury excretion accounted for 38. 2% ~ 50.4% of HgS intake; while the mercury excretion accounted for72.2% -86.6% on the tenth day after administration; The a-mount of HgS discharged in the feces decreased rapidly on the fourth day after drug discontinuation. Only extreme trace of mercury excreted from urine with dose-dependent pattern, and the mercury excretion maintained the high

  14. Oak Ridge Health Studies Phase 1 report, Volume 2: Part D, Dose Reconstruction Feasibility Study. Tasks 6, Hazard summaries for important materials at the Oak Ridge Reservation

    Energy Technology Data Exchange (ETDEWEB)

    Bruce, G.M.; Walker, L.B.; Widner, T.E.

    1993-09-01

    The purpose of Task 6 of Oak Ridge Phase I Health Studies is to provide summaries of current knowledge of toxic and hazardous properties of materials that are important for the Oak Ridge Reservation. The information gathered in the course of Task 6 investigations will support the task of focussing any future health studies efforts on those operations and emissions which have likely been most significant in terms of off-site health risk. The information gathered in Task 6 efforts will likely also be of value to individuals evaluating the feasibility of additional health,study efforts (such as epidemiological investigations) in the Oak Ridge area and as a resource for citizens seeking information on historical emissions.

  15. Reconstruction of total grain size distribution of the climactic phase of a long-lasting eruption: the example of the 2008-2013 Chaitén eruption

    Science.gov (United States)

    Alfano, Fabrizio; Bonadonna, Costanza; Watt, Sebastian; Connor, Chuck; Volentik, Alain; Pyle, David M.

    2016-07-01

    The 2008-2013 eruption of Chaitén Volcano (Chile) was a long-lasting eruption whose climactic phase (May 6, 2008) produced a sub-Plinian plume, with height ranging between 14 and 20 km that dispersed to the NE, reaching the Atlantic coast of Argentina. The erupted material was mainly of lithic origin (˜77 wt%), resulting in a unimodal total grain size distribution (TGSD) dominated by coarse ash (77 wt%), with Mdϕ of 2.7 and σϕ of 2.4. Lapilli clasts (>2 mm) dominate the proximal deposit within ~20 km of the vent, while coarse (63 μm-2 mm) and fine ash (400 km) do not significantly affect the determination of the TGSD. In contrast, gaps in data sampling in the medial deposit (in particular the gap between 50 and 350 km from vent that coincides with shifts in sedimentation regimes) have large impacts on estimates of TGSD. Particle number distribution for this deposit is characterized by a high power-law exponent (3.0) following a trend very similar to the vesicle size distribution in the juvenile pyroclasts. Although this could be taken to indicate a bubble-driven fragmentation process, we suggest that fragmentation was more likely the result of a shear-driven process because of the predominance of non-vesicular products (lithics and obsidians) and the large fraction of coarse ash in the TGSD.

  16. Breast Reconstruction After Mastectomy

    Science.gov (United States)

    ... reconstruction with or without radiotherapy. Current Opinion in Obstetrics and Gynecology 2011;23(1):44–50. [PubMed Abstract] Barry M, Kell MR. Radiotherapy and breast reconstruction: a meta-analysis. Breast ...

  17. Structured illumination microscopy image reconstruction algorithm

    OpenAIRE

    Lal, Amit; Shan, Chunyan; Xi, Peng

    2016-01-01

    Structured illumination microscopy (SIM) is a very important super-resolution microscopy technique, which provides high speed super-resolution with about two-fold spatial resolution enhancement. Several attempts aimed at improving the performance of SIM reconstruction algorithm have been reported. However, most of these highlight only one specific aspect of the SIM reconstruction -- such as the determination of the illumination pattern phase shift accurately -- whereas other key elements -- s...

  18. Surfaces, Digitisations and Reconstructions

    DEFF Research Database (Denmark)

    Christensen, Sabrina Tang

    2015-01-01

    We present a new digital reconstruction of r-regular sets in three-dimensional Euclidean space. We introduce a vector field and analyse the relation between the topologies of the boundaries of the r-regular set and its reconstruction. This reconstruction can be carried out faster than prior model...

  19. CURRENT CONCEPTS IN ACL RECONSTRUCTION

    Directory of Open Access Journals (Sweden)

    Freddie H. Fu

    2008-09-01

    's most experienced surgeons to produce a so called "Bible of ACL". The most current concepts not only for the clinical approach but the latest knowledge in basic sciences which the clinical concepts are based on also reviewed including biology, biomechanics, and kinematics. Advances in the diagnostic measures mainly MR imaging are also included. "Current Concepts in ACL Reconstruction" is a complete and the most up-to-date review providing the latest techniques for the treatment of ACL injuries in details, including the perspectives of the most experienced ACL surgeons of the world. Rich illustrations and an accompanying video CD-ROM comprehensively demonstrates the procedures and the techniques described in the book. The differences between single and double-bundle techniques, the technical details in different grafts choices, the technique and approach in the revision surgery are described in detail and explained in the anatomical basis. Pearls, technical pitfalls, personal experience and advices of the most experienced ACL surgeons not only from USA but also from the other pioneer countries of the world in ACL surgery may be the most welcomed parts of the book even by the highly experienced ACL surgeons especially for technically demanding procedures like double-bundle reconstruction. Postoperative rehabilitation described in phases provides the current rehabilitation concept after ACL reconstruction. Outcome measures to assess success after surgery are also reviewed and aspects for future are recommended. Principles and experiences in the navigation technologies in ACL reconstruction are providing the reader new perspectives for future possibilities in diagnosis and treatment. Review of basic sciences, advances in technology and clinical approach from history to future also clearly demonstrates the evolution "where are we and the way to go" and future aspects in the treatment of a thorn ACL

  20. Automatic phase point determination of minimal motion reconstruction intervals with motion maps in ECG-gated CT diagnostics of coronary sclerosis; Die automatisierte Bestimmung eines optimalen Rekonstruktionsintervalls bei der nativen EKG-gegateten CT-Diagnostik der Koronarsklerose mittels ''Motion Maps''

    Energy Technology Data Exchange (ETDEWEB)

    Klink, Thorsten; Van Stevendaal, U.; Regier, M.; Adam, G.; Begemann, P.G. [Klinik und Poliklinik fuer Diagnostische und Interventionelle Radiologie, Universitaetsklinikum Hamburg-Eppendorf (Germany); Hoffmann, M.H. [Klinik fuer Diagnostische und Interventionelle Radiologie, Universitaetsklinikum Ulm (Germany); Grass, M. [Forschungslaboratorien, Philips Technologie GmbH, Hamburg (Germany)

    2009-07-15

    Purpose: Cardio-CT motion maps for automated cardiac phase point determination were evaluated for image quality and reliability of coronary calcium scores. Materials and methods: 24 patients underwent ECG-gated non-enhanced cardiac CT for calcium scoring. From raw data the motion map software reconstructed low-resolution images in 2% steps of the RR interval and automatically generated cardiac motion maps for determination of minimal motion phase points. Diagnostic images were reconstructed in 10% steps of the RR interval (RR data) and according to the motion maps (MM data). For every data set, the Agatston score was calculated. Image quality was evaluated by two independent observers. Image quality was correlated with the Agatston score. Results: The Agatston score calculated over the RR interval showed a mean variation of 127 with 41% of patients assigned to more than one risk group. If the motion map RR intervals were calculated, only 16% patients were assigned to different risk categories with a mean variation of 55. Regarding the image quality, the inter-rater variance was moderate. The best image quality was achieved with the 30-40% and 70 - 80% RR interval. Over the complete RR interval motion map reconstructions produced a good image quality. Conclusion: Calculation of the Agatston score requires selection of the proper reconstruction interval to guarantee the assignment of patients into the appropriate risk category. By using motion maps for phase point determination, the amount of necessary reconstruction can be minimized and the assignment to different risk groups is also reduced. (orig.)

  1. The Algebraic Reconstruction Technique (ART)

    International Nuclear Information System (INIS)

    Projections of charged particle beam current density (profiles) are frequently used as a measure of beam position and size. In conventional practice only two projections, usually horizontal and vertical, are measured. This puts a severe limit on the detail of information that can be achieved. A third projection provides a significant improvement. The Algebraic Reconstruction Technique (ART) uses three or more projections to reconstruct 3-dimensional density profiles. At the 200 MeV H-linac, we have used this technique to measure beam density, and it has proved very helpful, especially in helping determine if there is any coupling present in x-y phase space. We will present examples of measurements of current densities using this technique

  2. Cosmic Tidal Reconstruction

    CERN Document Server

    Zhu, Hong-Ming; Yu, Yu; Er, Xinzhong; Chen, Xuelei

    2015-01-01

    The gravitational coupling of a long wavelength tidal field with small scale density fluctuations leads to anisotropic distortions of the locally measured small scale matter correlation function. Since the local correlation function is statistically isotropic in the absence of such tidal interactions, the tidal distortions can be used to reconstruct the long wavelength tidal field and large scale density field in analogy with the cosmic microwave background lensing reconstruction. In this paper we present in detail a formalism for the cosmic tidal reconstruction and test the reconstruction in numerical simulations. We find that the density field on large scales can be reconstructed with good accuracy and the cross correlation coefficient between the reconstructed density field and the original density field is greater than 0.9 on large scales ($k\\lesssim0.1h/\\mathrm{Mpc}$). This is useful in the 21cm intensity mapping survey, where the long wavelength radial modes are lost due to foreground subtraction proces...

  3. Holographic microscopy reconstruction in both object and image half spaces with undistorted 3D grid

    CERN Document Server

    Verrier, Nicolas; Tessier, Gilles; Gross, Michel

    2015-01-01

    We propose a holographic microscopy reconstruction method, which propagates the hologram, in the object half space, in the vicinity of the object. The calibration yields reconstructions with an undistorted reconstruction grid i.e. with orthogonal x, y and z axis and constant pixels pitch. The method is validated with an USAF target imaged by a x60 microscope objective, whose holograms are recorded and reconstructed for different USAF locations along the longitudinal axis:-75 to +75 {\\mu}m. Since the reconstruction numerical phase mask, the reference phase curvature and MO form an afocal device, the reconstruction can be interpreted as occurring equivalently in the object or in image half space.

  4. Re-construction

    OpenAIRE

    Bernadette Marie Devilat

    2013-01-01

    Re-construct: to build again. The necessary reconstruction process after an earthquake can be seen as an opportunity to improve previous conditions. All damaged buildings undergo a renovation process in which every piece is carefully returned to its original place. The photograph shows roof reconstruction work in San Pedro de Alcántara, a heritage area in the central valley of Chile, which was particularly affected by the 2010 earthquake. 

  5. Flexor pulley reconstruction.

    Science.gov (United States)

    Dy, Christopher J; Daluiski, Aaron

    2013-05-01

    Flexor pulley reconstruction is a challenging surgery. Injuries often occur after traumatic lacerations or forceful extension applied to an acutely flexed finger. Surgical treatment is reserved for patients with multiple closed pulley ruptures, persistent pain, or dysfunction after attempted nonoperative management of a single pulley rupture, or during concurrent or staged flexor tendon repair or reconstruction. If the pulley cannot be repaired primarily, pulley reconstruction can be performed using graft woven into remnant pulley rim or looping graft around the phalanx. Regardless of the reconstructive technique, the surgeon should emulate the length, tension, and glide of the native pulley. PMID:23660059

  6. Image Reconstruction. Chapter 13

    International Nuclear Information System (INIS)

    This chapter discusses how 2‑D or 3‑D images of tracer distribution can be reconstructed from a series of so-called projection images acquired with a gamma camera or a positron emission tomography (PET) system [13.1]. This is often called an ‘inverse problem’. The reconstruction is the inverse of the acquisition. The reconstruction is called an inverse problem because making software to compute the true tracer distribution from the acquired data turns out to be more difficult than the ‘forward’ direction, i.e. making software to simulate the acquisition. There are basically two approaches to image reconstruction: analytical reconstruction and iterative reconstruction. The analytical approach is based on mathematical inversion, yielding efficient, non-iterative reconstruction algorithms. In the iterative approach, the reconstruction problem is reduced to computing a finite number of image values from a finite number of measurements. That simplification enables the use of iterative instead of mathematical inversion. Iterative inversion tends to require more computer power, but it can cope with more complex (and hopefully more accurate) models of the acquisition process

  7. Bitzer's Model Reconstructed.

    Science.gov (United States)

    Lybarger, Scott; Smith, Craig R.

    1996-01-01

    Reconstructs Lloyd Bitzer's situational model to serve as a guide for the generation of multiperspectival critical assessments of rhetorical discourse. Uses two of President Bush's speeches on the drug crisis to illustrate how the reconstructed model can account for such modern problems as multiple audiences, perceptions, and exigencies. (PA)

  8. Mandibular reconstruction using bone allografts

    International Nuclear Information System (INIS)

    Further understanding of bone healing mechanisms, bone physiology and bone biology, transplantation immunology, and development of Tissue Banking procedures has enabled oral and maxillofacial surgeons to reconstruct even the most difficult bony defects successfully with the preserved allogeneic bone implant. Although it had been known that bone allografts were clinically effective, its application has not been widespread until the reports of Inclan (I 942), Hyatt and Butler (I 950), and Wilson (I 95 1). Tissue Banking provides the surgeon with a readily available, relatively inexpensive, and relatively safe selection of allogeneic bone for clinical use. Now autogenous bone and allogeneic bone implants present a wide variety of surgical options to surgeons, whether used separately or in combination. The surgeons are able to make judicious and fruitful choices, only with a thorough knowledge of the above-mentioned biological principles and skillful techniques. Many kinds of bone grafting techniques have been tried for reconstructing defective osseous tissues of the oral and maxillofacial region, though they have varying degrees of success. The osseous defects which require grafting include those of various size, shape, position, or amount. Unlike autogenous grafts, whose function is to provide osteogenic cells, allografts are purely passive, offering only a matrix for the inductive phase of bone healing. The condition of the recipient bed is of primary importance, because the host must produce all of the essential elements for the bone allograft to become incorporated. Depending on the processing methods of the allogeneic bone, the bone graft materials have different qualities, different healing potentials and different indications. Proper selection of grafts and surgical techniques requires an understanding of graft immunology and the mechanisms of graft healing. The surgeons should know about the biological principles to raise the clinical success rate

  9. Classical and Quantum-Mechanical State Reconstruction

    Science.gov (United States)

    Khanna, F. C.; Mello, P. A.; Revzen, M.

    2012-01-01

    The aim of this paper is to present the subject of state reconstruction in classical and in quantum physics, a subject that deals with the experimentally acquired information that allows the determination of the physical state of a system. Our first purpose is to explain a method for retrieving a classical state in phase space, similar to that…

  10. The CMS Reconstruction Software

    Science.gov (United States)

    Lange, David J.; CMS Collaboration

    2011-12-01

    We report on the status and plans for the event reconstruction software of the CMS experiment. The CMS reconstruction algorithms are the basis for a wide range of data analysis approaches currently under study by the CMS collaboration using the first high-energy run of the LHC. These algorithms have been primarily developed and validated using simulated data samples, and are now being commissioned with LHC proton-proton collision data samples. The CMS reconstruction is now operated routinely on all events triggered by the CMS detector, both in a close to real-time prompt reconstruction processing and in frequent passes over the full recorded CMS data set. We discuss the overall software design, development cycle, computational requirements and performance, recent operational performance, and planned improvements of the CMS reconstruction software.

  11. Image reconstruction for x-ray holographic microscopy

    International Nuclear Information System (INIS)

    The authors have demonstrated direct Fourier reconstruction of a simple three-dimensional object from multiple Fourier transform holograms recorded at different incidence angles. Following phase recovery of the scattered field based on the reference scatterer, the authors used standard diffraction tomography techniques to reconstruct the object scattering potential. For systems of low numerical aperture, algebraic techniques which assume straight rays were demonstrated to produce images with fewer reconstruction artifacts. These techniques allow the use of a priori knowledge of the object; this approach should be extended into diffraction-based reconstruction algorithms

  12. Numerical methods for phase retrieval

    CERN Document Server

    Osherovich, Eliyahu

    2012-01-01

    In this work we consider the problem of reconstruction of a signal from the magnitude of its Fourier transform, also known as phase retrieval. The problem arises in many areas of astronomy, crystallography, optics, and coherent diffraction imaging (CDI). Our main goal is to develop an efficient reconstruction method based on continuous optimization techniques. Unlike current reconstruction methods, which are based on alternating projections, our approach leads to a much faster and more robust method. However, all previous attempts to employ continuous optimization methods, such as Newton-type algorithms, to the phase retrieval problem failed. In this work we provide an explanation for this failure, and based on this explanation we devise a sufficient condition that allows development of new reconstruction methods---approximately known Fourier phase. We demonstrate that a rough (up to $\\pi/2$ radians) Fourier phase estimate practically guarantees successful reconstruction by any reasonable method. We also pres...

  13. Delayed breast implant reconstruction

    DEFF Research Database (Denmark)

    Hvilsom, Gitte B.; Hölmich, Lisbet R.; Steding-Jessen, Marianne;

    2011-01-01

    -stage procedures. From the Danish Registry for Plastic Surgery of the Breast, which has prospectively registered data for women undergoing breast implantations since 1999, we identified 559 women without a history of radiation therapy undergoing 592 delayed breast reconstructions following breast cancer during the......Studies of complications following reconstructive surgery with implants among women with breast cancer are needed. As the, to our knowledge, first prospective long-term study we evaluated the occurrence of complications following delayed breast reconstruction separately for one- and two...

  14. Large Scale 3D Image Reconstruction in Optical Interferometry

    CERN Document Server

    Schutz, Antony; Mary, David; Thiébaut, Eric; Soulez, Ferréol

    2015-01-01

    Astronomical optical interferometers (OI) sample the Fourier transform of the intensity distribution of a source at the observation wavelength. Because of rapid atmospheric perturbations, the phases of the complex Fourier samples (visibilities) cannot be directly exploited , and instead linear relationships between the phases are used (phase closures and differential phases). Consequently, specific image reconstruction methods have been devised in the last few decades. Modern polychromatic OI instruments are now paving the way to multiwavelength imaging. This paper presents the derivation of a spatio-spectral ("3D") image reconstruction algorithm called PAINTER (Polychromatic opticAl INTErferometric Reconstruction software). The algorithm is able to solve large scale problems. It relies on an iterative process, which alternates estimation of polychromatic images and of complex visibilities. The complex visibilities are not only estimated from squared moduli and closure phases, but also from differential phase...

  15. Wavefront reconstruction using computer-generated holograms

    Science.gov (United States)

    Schulze, Christian; Flamm, Daniel; Schmidt, Oliver A.; Duparré, Michael

    2012-02-01

    We propose a new method to determine the wavefront of a laser beam, based on modal decomposition using computer-generated holograms (CGHs). Thereby the beam under test illuminates the CGH with a specific, inscribed transmission function that enables the measurement of modal amplitudes and phases by evaluating the first diffraction order of the hologram. Since we use an angular multiplexing technique, our method is innately capable of real-time measurements of amplitude and phase, yielding the complete information about the optical field. A measurement of the Stokes parameters, respectively of the polarization state, provides the possibility to calculate the Poynting vector. Two wavefront reconstruction possibilities are outlined: reconstruction from the phase for scalar beams and reconstruction from the Poynting vector for inhomogeneously polarized beams. To quantify single aberrations, the reconstructed wavefront is decomposed into Zernike polynomials. Our technique is applied to beams emerging from different kinds of multimode optical fibers, such as step-index, photonic crystal and multicore fibers, whereas in this work results are exemplarily shown for a step-index fiber and compared to a Shack-Hartmann measurement that serves as a reference.

  16. Surgical Ventricular Reconstruction

    Medline Plus

    Full Text Available SURGICAL VENTRICULAR RECONSTRUCTION MONTEFIORE-EINSTEIN HEART CENTER NEW YORK CITY, NEW YORK February 13, 2008 00:00:09 NARRATOR: Welcome to the Montefiore-Einstein Heart Center in ...

  17. Surgical Ventricular Reconstruction

    Medline Plus

    Full Text Available SURGICAL VENTRICULAR RECONSTRUCTION MONTEFIORE-EINSTEIN HEART CENTER NEW YORK CITY, NEW YORK February 13, 2008 00:00:09 NARRATOR: Welcome to the Montefiore-Einstein Heart Center in New York City. In ...

  18. Prairie Reconstruction Initiative

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The purpose of the Prairie Reconstruction Initiative Advisory Team (PRIAT) is to identify and take steps to resolve uncertainties in the process of prairie...

  19. Overview of Image Reconstruction

    Energy Technology Data Exchange (ETDEWEB)

    Marr, R. B.

    1980-04-01

    Image reconstruction (or computerized tomography, etc.) is any process whereby a function, f, on Rn is estimated from empirical data pertaining to its integrals, ∫f(x) dx, for some collection of hyperplanes of dimension k < n. The paper begins with background information on how image reconstruction problems have arisen in practice, and describes some of the application areas of past or current interest; these include radioastronomy, optics, radiology and nuclear medicine, electron microscopy, acoustical imaging, geophysical tomography, nondestructive testing, and NMR zeugmatography. Then the various reconstruction algorithms are discussed in five classes: summation, or simple back-projection; convolution, or filtered back-projection; Fourier and other functional transforms; orthogonal function series expansion; and iterative methods. Certain more technical mathematical aspects of image reconstruction are considered from the standpoint of uniqueness, consistency, and stability of solution. The paper concludes by presenting certain open problems. 73 references. (RWR)

  20. Surgical Ventricular Reconstruction

    Medline Plus

    Full Text Available ... reconstruction. This study is going to be a land…landmark study. And in all likelihood will influence ... improve postoperatively. But, nevertheless, this is an acute change and may take some time for the myocardium ...

  1. Overview of image reconstruction

    International Nuclear Information System (INIS)

    Image reconstruction (or computerized tomography, etc.) is any process whereby a function, f, on R/sup n/ is estimated from empirical data pertaining to its integrals, ∫f(x) dx, for some collection of hyperplanes of dimension k < n. The paper begins with background information on how image reconstruction problems have arisen in practice, and describes some of the application areas of past or current interest; these include radioastronomy, optics, radiology and nuclear medicine, electron microscopy, acoustical imaging, geophysical tomography, nondestructive testing, and NMR zeugmatography. Then the various reconstruction algorithms are discussed in five classes: summation, or simple back-projection; convolution, or filtered back-projection; Fourier and other functional transforms; orthogonal function series expansion; and iterative methods. Certain more technical mathematical aspects of image reconstruction are considered from the standpoint of uniqueness, consistency, and stability of solution. The paper concludes by presenting certain open problems. 73 references

  2. Breast reconstruction - natural tissue

    Science.gov (United States)

    After a mastectomy , some women choose to have cosmetic surgery to remake their breast. This type of surgery ... Risks of anesthesia and surgery are: Reactions to medicines Breathing problems Bleeding, blood clots , or infection Risks of breast reconstruction with ...

  3. Permutationally invariant state reconstruction

    CERN Document Server

    Moroder, Tobias; Toth, Geza; Schwemmer, Christian; Niggebaum, Alexander; Gaile, Stefanie; Gühne, Otfried; Weinfurter, Harald

    2012-01-01

    Feasible tomography schemes for large particle numbers must possess, besides an appropriate data acquisition protocol, also an efficient way to reconstruct the density operator from the observed finite data set. Since state reconstruction typically requires the solution of a non-linear large-scale optimization problem, this is a major challenge in the design of scalable tomography schemes. Here we present an efficient state reconstruction scheme for permutationally invariant quantum state tomography. It works for all common state-of-the-art reconstruction principles, including, in particular, maximum likelihood and least squares methods, which are the preferred choices in today's experiments. This high efficiency is achieved by greatly reducing the dimensionality of the problem employing a particular representation of permutationally invariant states known from spin coupling combined with convex optimization, which has clear advantages regarding speed, control and accuracy in comparison to commonly employed n...

  4. Surgical Ventricular Reconstruction

    Medline Plus

    Full Text Available ... a better procedure, the ventricular reconstruction or heart transplantation. This particular viewer actually saw our previous video on heart transplantation. And to answer that question, they are both ...

  5. On TPC cluster reconstruction

    CERN Document Server

    Dydak, F; Nefedov, Y; Wotschack, J; Zhemchugov, A

    2004-01-01

    For a bias-free momentum measurement of TPC tracks, the correct determination of cluster positions is mandatory. We argue in particular that (i) the reconstruction of the entire longitudinal signal shape in view of longitudinal diffusion, electronic pulse shaping, and track inclination is important both for the polar angle reconstruction and for optimum r phi resolution; and that (ii) self-crosstalk of pad signals calls for special measures for the reconstruction of the z coordinate. The problem of 'shadow clusters' is resolved. Algorithms are presented for accepting clusters as 'good' clusters, and for the reconstruction of the r phi and z cluster coordinates, including provisions for 'bad' pads and pads next to sector boundaries, respectively.

  6. Surgical Ventricular Reconstruction

    Medline Plus

    Full Text Available ... He has not been readmitted for any reasons related to heart failure. 00:41:57 ROBERT E. ... question, because it really deals with whether anything related to surgical ventricular reconstruction would add to the ...

  7. Chalet. Reconstruction from Memory

    OpenAIRE

    Gheysen, Eva

    2015-01-01

    In the research project several design tactics are developed in order to counteract the phenomenon of experiential erosion. This particular project explored one of the tactics: Reconstruction from Memory. When reconstructing space from memory, isolated spatial fragments from the past are reformed into a new, decontextualized construct that represents the most memorable experiences evoked by that space. These memories give insight in which architectural features strongly affect our experience ...

  8. Reconstructing baryon oscillations

    OpenAIRE

    Noh, Yookyung; White, Martin; Padmanabhan, Nikhil

    2009-01-01

    The baryon acoustic oscillation (BAO) method for constraining the expansion history is adversely affected by non-linear structure formation, which washes out the correlation function peak created at decoupling. To increase the constraining power of low z BAO experiments, it has been proposed that one use the observed distribution of galaxies to "reconstruct'' the acoustic peak. Recently Padmanabhan, White and Cohn provided an analytic formalism for understanding how reconstruction works withi...

  9. Cosmic tidal reconstruction

    Science.gov (United States)

    Zhu, Hong-Ming; Pen, Ue-Li; Yu, Yu; Er, Xinzhong; Chen, Xuelei

    2016-05-01

    The gravitational coupling of a long-wavelength tidal field with small-scale density fluctuations leads to anisotropic distortions of the locally measured small-scale matter correlation function. Since the local correlation function is known to be statistically isotropic in the absence of such tidal interactions, the tidal distortions can be used to reconstruct the long-wavelength tidal field and large-scale density field in analogy with the cosmic microwave background lensing reconstruction. In this paper we present the theoretical framework of cosmic tidal reconstruction and test the reconstruction in numerical simulations. We find that the density field on large scales can be reconstructed with good accuracy and the cross-correlation coefficient between the reconstructed density field and the original density field is greater than 0.9 on large scales (k ≲0.1 h /Mpc ), with the filter scale ˜1.25 Mpc /h . This is useful in the 21 cm intensity mapping survey, where the long-wavelength radial modes are lost due to a foreground subtraction process.

  10. Permutationally invariant state reconstruction

    DEFF Research Database (Denmark)

    Moroder, Tobias; Hyllus, Philipp; Tóth, Géza;

    2012-01-01

    Feasible tomography schemes for large particle numbers must possess, besides an appropriate data acquisition protocol, an efficient way to reconstruct the density operator from the observed finite data set. Since state reconstruction typically requires the solution of a nonlinear large-scale opti......Feasible tomography schemes for large particle numbers must possess, besides an appropriate data acquisition protocol, an efficient way to reconstruct the density operator from the observed finite data set. Since state reconstruction typically requires the solution of a nonlinear large......-scale optimization problem, this is a major challenge in the design of scalable tomography schemes. Here we present an efficient state reconstruction scheme for permutationally invariant quantum state tomography. It works for all common state-of-the-art reconstruction principles, including, in particular, maximum...... likelihood and least squares methods, which are the preferred choices in today's experiments. This high efficiency is achieved by greatly reducing the dimensionality of the problem employing a particular representation of permutationally invariant states known from spin coupling combined with convex...

  11. Current Sensor Fault Reconstruction for PMSM Drives.

    Science.gov (United States)

    Huang, Gang; Luo, Yi-Ping; Zhang, Chang-Fan; He, Jing; Huang, Yi-Shan

    2016-01-01

    This paper deals with a current sensor fault reconstruction algorithm for the torque closed-loop drive system of an interior PMSM. First, sensor faults are equated to actuator ones by a new introduced state variable. Then, in αβ coordinates, based on the motor model with active flux linkage, a current observer is constructed with a specific sliding mode equivalent control methodology to eliminate the effects of unknown disturbances, and the phase current sensor faults are reconstructed by means of an adaptive method. Finally, an αβ axis current fault processing module is designed based on the reconstructed value. The feasibility and effectiveness of the proposed method are verified by simulation and experimental tests on the RT-LAB platform. PMID:26840317

  12. Current Sensor Fault Reconstruction for PMSM Drives

    Directory of Open Access Journals (Sweden)

    Gang Huang

    2016-01-01

    Full Text Available This paper deals with a current sensor fault reconstruction algorithm for the torque closed-loop drive system of an interior PMSM. First, sensor faults are equated to actuator ones by a new introduced state variable. Then, in αβ coordinates, based on the motor model with active flux linkage, a current observer is constructed with a specific sliding mode equivalent control methodology to eliminate the effects of unknown disturbances, and the phase current sensor faults are reconstructed by means of an adaptive method. Finally, an αβ axis current fault processing module is designed based on the reconstructed value. The feasibility and effectiveness of the proposed method are verified by simulation and experimental tests on the RT-LAB platform.

  13. First attempt of neutron quantum state reconstruction

    International Nuclear Information System (INIS)

    The neutron interferometer set-up S18 at the ILL reactor has been used for the first neutron quantum state reconstruction experiment. By a simultaneous measurement of the coherence function and of the modulated momentum distribution behind the interferometer, the Wigner function of various quantum states can be reconstructed. This is equivalent to knowledge of the particle wavefunction. Its spatial dimension follows from the measurement of the coherence function, which is the autocorrelation function of the wavefunction and the shape in momentum space follows from momentum post-selection experiments. Non-orthogonal traces through the (x, k)-phase space have to be measured for an unambiguous reconstruction. Nearly classical (coherent) and non-classical states in the form of Schroedinger cat-like states have been identified. Comparisons of calculated and measured Wigner functions will be shown

  14. The CMS Muon Reconstruction Software

    CERN Document Server

    Trocino, Daniele

    2009-01-01

    Muonic final states will provide clean signatures for many physics processes at the LHC. One of the main goals of the Compact Muon Solenoid (CMS) design is thus to ensure efficient and accurate identification and reconstruction of muons. A sophisticated muon system is used for muon identification and stand-alone reconstruction and the inner silicon tracker exploits the high magnetic field to ensure a very precise transverse momentum resolution. The global reconstruction algorithms combine muons reconstructed in the dedicated spectrometer with tracks reconstructed in the inner detector. The CMS reconstruction software is well suited for both offline reconstruction and online event selection (HLT) and its performance has been studied in detail using Monte Carlo simulations. The muon reconstruction has also been employed successfully to reconstruct cosmic muons traversing the CMS detector. The design of the CMS muon identification and reconstruction is presented, as well as its performance on simulated and cosmi...

  15. Nipple-areola complex reconstruction

    OpenAIRE

    Nimboriboonporn, Anongporn; Chuthapisith, Suebwong

    2014-01-01

    Nipple areolar reconstruction (NAC) was introduced since 1940s and evolved as parallel with breast reconstruction since era of breast cancer treatment. It consists of nipple and areolar reconstruction. Ideal reconstruction of the NAC requires symmetry in position, size, shape, texture, and pigmentation and permanent projection. There are many innovative ways to create a nipple and each method has its unique characteristics that apply to certain breast types. NAC reconstruction techniques comp...

  16. Running image reconstruction for intraoperative MRI

    International Nuclear Information System (INIS)

    Recently there has been a growing interest in the use of MR-guided navigation to improve the safety and effectiveness of surgical procedures. The purpose of our work was to develop and demonstrate an imaging strategy which allows a physician to continue operating without the delays caused from imaging. Phase scrambling Fourier transform imaging technique allows for a localized image to be reconstructed from the segmented signal. Therefore, continuous imaging (a running reconstruction) of MR images is feasible by combining this localized imaging property with fast image reconstruction. Since local images are updated in several TR periods, even during data acquisition, the orientation or location of the subject (devices) can be monitored faster than by the conventional fast imaging technique. Feasibility studies of the proposed imaging were performed using a 0.0183T MRI scanner and a personal computer for image reconstruction. Since the image SNR obtained by the ultra-low field MRI scanner was quite small, experiments using the phantom were performed. The proposed running reconstruction strategy appears to be feasible for a variety of guided interventional MRI procedures. It also appears to provide some important advantages over conventional 2DFT imaging. The proposed technique can be readily applied in a well established MRI equipped with the fast imaging technique by pulsing the resistive shim coils that are already present. (author)

  17. Alternative reconstruction after pancreaticoduodenectomy

    Directory of Open Access Journals (Sweden)

    Cooperman Avram M

    2008-01-01

    Full Text Available Abstract Background Pancreaticoduodenectomy is the procedure of choice for tumors of the head of the pancreas and periampulla. Despite advances in surgical technique and postoperative care, the procedure continues to carry a high morbidity rate. One of the most common morbidities is delayed gastric emptying with rates of 15%–40%. Following two prolonged cases of delayed gastric emptying, we altered our reconstruction to avoid this complication altogether. Subsequently, our patients underwent a classic pancreaticoduodenectomy with an undivided Roux-en-Y technique for reconstruction. Methods We reviewed the charts of our last 13 Whipple procedures evaluating them for complications, specifically delayed gastric emptying. We compared the outcomes of those patients to a control group of 15 patients who underwent the Whipple procedure with standard reconstruction. Results No instances of delayed gastric emptying occurred in patients who underwent an undivided Roux-en-Y technique for reconstruction. There was 1 wound infection (8%, 1 instance of pneumonia (8%, and 1 instance of bleeding from the gastrojejunal staple line (8%. There was no operative mortality. Conclusion Use of the undivided Roux-en-Y technique for reconstruction following the Whipple procedure may decrease the incidence of delayed gastric emptying. In addition, it has the added benefit of eliminating bile reflux gastritis. Future randomized control trials are recommended to further evaluate the efficacy of the procedure.

  18. Real-time wavefront reconstruction from intensity measurements

    OpenAIRE

    Smith, C.; Marinica, R.; Verhaegen, M.

    2013-01-01

    We propose an efficient approximation to the nonlinear phase diversity method for wavefront reconstruction from intensity measurements. The new method, iterative linear phase diversity (ILPD), assumes that the residual phase aberration is small and makes use of a first order Taylor expansion of the point spread function (PSF) performed for an arbitrary (large) diversity in order to optimize the phase retrieval. For static aberrations, ILPD makes use of two images collected at each iteration o...

  19. Breast Reconstruction with Microvascular

    Directory of Open Access Journals (Sweden)

    David W. Chang

    2012-01-01

    Full Text Available The free muscle-sparing transverse rectus abdominis myocutaneous (MS-TRAM and deepinferior epigastric perforator (DIEP flaps involve transferring skin and subcutaneous tissuefrom the lower abdominal area and have many features that make them well suited forbreast reconstruction. The robust blood supply of the free flap reduces the risk of fat necrosisand also enables aggressive shaping of the flap for breast reconstruction to optimize theaesthetic outcome. In addition, the free MS-TRAM flap and DIEP flap require minimal donorsitesacrifice in most cases. With proper patient selection and safe surgical technique, the freeMS-TRAM flap and DIEP flap can transfer the lower abdominal skin and subcutaneous tissueto provide an aesthetically pleasing breast reconstruction with minimal donor-site morbidity.

  20. Reconstructing random media

    International Nuclear Information System (INIS)

    We formulate a procedure to reconstruct the structure of general random heterogeneous media from limited morphological information by extending the methodology of Rintoul and Torquato [J. Colloid Interface Sci. 186, 467 (1997)] developed for dispersions. The procedure has the advantages that it is simple to implement and generally applicable to multidimensional, multiphase, and anisotropic structures. Furthermore, an extremely useful feature is that it can incorporate any type and number of correlation functions in order to provide as much morphological information as is necessary for accurate reconstruction. We consider a variety of one- and two-dimensional reconstructions, including periodic and random arrays of rods, various distribution of disks, Debye random media, and a Fontainebleau sandstone sample. We also use our algorithm to construct heterogeneous media from specified hypothetical correlation functions, including an exponentially damped, oscillating function as well as physically unrealizable ones. copyright 1998 The American Physical Society

  1. Reconstructed Jets at RHIC

    CERN Document Server

    Salur, Sevil

    2010-01-01

    To precisely measure jets over a large background such as pile up in high luminosity p+p collisions at LHC, a new generation of jet reconstruction algorithms is developed. These algorithms are also applicable to reconstruct jets in the heavy ion environment where large event multiplicities are produced. Energy loss in the medium created in heavy ion collisions are already observed indirectly via inclusive hadron distributions and di-hadron correlations. Jets can be used to study this energy loss in detail with reduced biases. We review the latest results on jet-medium interactions as seen in A+A collisions at RHIC, focusing on the recent progress on jet reconstruction in heavy ion collisions.

  2. orbital selective correlation reduce in collapse tetragonal phase of CaFe2(As0.935P0.065)2 and electronic structure reconstruction studied by angel resolved photoemission spectroscopy

    Science.gov (United States)

    Zeng, Lingkun

    We performed an angle-resolved photoemission spectroscopy (ARPES) study of the CaFe2(As0.935P0.065)2 in the collapse tetragonal(CT) phase and uncollapse tetragonal(UCT) phase. We find in the CT phase the electronic correlation dramatically reduces respective to UCT phase. Meanwhile, the reduction of correlation in CT phase show an orbital selective effect: correlation in dxy reduces the most, and then dxz/yz, while the one in dz2-r2 almost keeps the same. In CT phase, almost all bands sink downwards to higher binding energy, leading to the hole like bands around Brillouin zone(BZ) center sink below EF compared with UCT phase. However, the electron pocket around Brillouin Zone(BZ) corner(M) in UCT phase, forms a hole pocket around BZ center(Z point) in CT phase. Moreover, the dxy exhibits larger movement down to higher binding energy, resulting in farther away from dyz/xz and closer to dxy.We propose the electron filling ,namely high spin state in UCT phase to low spin state in CT phase(due to competing between crystal structure field and Hund's coupling), other than the Fermi surface nesting might be responsible for the absent of magnetic ordering.

  3. Vertex Reconstruction in CMS

    CERN Document Server

    Chabanat, E; D'Hondt, J; Vanlaer, P; Prokofiev, K; Speer, T; Frühwirth, R; Waltenberger, W

    2005-01-01

    Because of the high track multiplicity in the final states expected in proton collisions at the LHC experiments, novel vertex reconstruction algorithms are required. The vertex reconstruction problem can be decomposed into a pattern recognition problem ("vertex finding") and an estimation problem ("vertex fitting"). Starting from least-square methods, ways to render the classical algorithms more robust are discussed and the statistical properties of the novel methods are shown. A whole set of different approaches for the vertex finding problem is presented and compared in relevant physics channels.

  4. The evolving breast reconstruction

    DEFF Research Database (Denmark)

    Thomsen, Jørn Bo; Gunnarsson, Gudjon Leifur

    2014-01-01

    The aim of this editorial is to give an update on the use of the propeller thoracodorsal artery perforator flap (TAP/TDAP-flap) within the field of breast reconstruction. The TAP-flap can be dissected by a combined use of a monopolar cautery and a scalpel. Microsurgical instruments are generally...... not needed. The propeller TAP-flap can be designed in different ways, three of these have been published: (I) an oblique upwards design; (II) a horizontal design; (III) an oblique downward design. The latissimus dorsi-flap is a good and reliable option for breast reconstruction, but has been...

  5. Reconstruction of inflation models

    Energy Technology Data Exchange (ETDEWEB)

    Myrzakulov, Ratbay; Sebastiani, Lorenzo [Eurasian National University, Department of General and Theoretical Physics and Eurasian Center for Theoretical Physics, Astana (Kazakhstan); Zerbini, Sergio [Universita di Trento, Dipartimento di Fisica, Trento (Italy); TIFPA, Istituto Nazionale di Fisica Nucleare, Trento (Italy)

    2015-05-15

    In this paper, we reconstruct viable inflationary models by starting from spectral index and tensor-to-scalar ratio from Planck observations. We analyze three different kinds of models: scalar field theories, fluid cosmology, and f(R)-modified gravity. We recover the well-known R{sup 2} inflation in Jordan-frame and Einstein-frame representation, the massive scalar inflaton models and two models of inhomogeneous fluid. A model of R{sup 2} correction to Einstein's gravity plus a ''cosmological constant'' with an exact solution for early-time acceleration is reconstructed. (orig.)

  6. Fast MR Spectroscopic Imaging Technologies and Data Reconstruction Methods

    Institute of Scientific and Technical Information of China (English)

    HUANGMin; LUSong-tao; LINJia-rui; ZHANYing-jian

    2004-01-01

    MRSI plays a more and more important role in clinical application. In this paper, we compare several fast MRSI technologies and data reconstruction methods. For the conventional phase encoding MRSI, the data reconstruction using FFT is simple. But the data acquisition is very time consuming and thus prohibitive in clinical settings. Up to now, the MRSI technologies based on echo-planar, spiral trajectories and sensitivity encoding are the fastest in data acquisition, but their data reconstruction is complex. EPSI reconstruction uses shift of odd and even echoes. Spiral SI uses gridding FFT. SENSE-SI, a new approach to reducing the acquisition time, uses the distinct spatial sensitivities of the individual coil elements to recover the missing encoding information. These improvements in data acquisition and image reconstruction provide a potential value of metabolic imaging as a clinical tool.

  7. Surgical Ventricular Reconstruction

    Medline Plus

    Full Text Available ... VENTRICULAR RECONSTRUCTION MONTEFIORE-EINSTEIN HEART CENTER NEW YORK CITY, NEW YORK February 13, 2008 00:00:09 ... the Montefiore-Einstein Heart Center in New York City. In just moments, you'll see an expert ...

  8. Breast Reconstruction with Tissue Expansion

    Medline Plus

    Full Text Available ... planning to do a left breast reconstruction, so lift up the flaps here and go underneath the ... breast reconstruction. In this case, we would usually lift the skin flap and the pectoralis major muscle ...

  9. Iterative reconstruction of magnetic induction using Lorentz transmission electron tomography

    International Nuclear Information System (INIS)

    Intense ongoing research on complex nanomagnetic structures requires a fundamental understanding of the 3D magnetization and the stray fields around the nano-objects. 3D visualization of such fields offers the best way to achieve this. Lorentz transmission electron microscopy provides a suitable combination of high resolution and ability to quantitatively visualize the magnetization vectors using phase retrieval methods. In this paper, we present a formalism to represent the magnetic phase shift of electrons as a Radon transform of the magnetic induction of the sample. Using this formalism, we then present the application of common tomographic methods particularly the iterative methods, to reconstruct the 3D components of the vector field. We present an analysis of the effect of missing wedge and the limited angular sampling as well as reconstruction of complex 3D magnetization in a nanowire using simulations. - Highlights: • We present a formalism to represent electron-optical magnetic phase shift as a Radon transform of the 3D magnetic induction of the nano-object. • We have analyzed four different tomographic reconstruction methods for vectorial data reconstruction. • Reconstruction methods were tested for varying experimental limitations such as limited tilt range and limited angular sampling. • The analysis showed that Gridrec and SIRT methods performed better with lower errors than other reconstruction methods

  10. Anterior cruciate ligament reconstruction

    International Nuclear Information System (INIS)

    This paper determines the efficacy of MR imaging in evaluation of the anterior cruciate ligament (ACL) following reconstructive surgery. Forty-three MR examinations were performed in 33 patients who had undergone previous arthroscopic ACL reconstruction with patellar bone-tendon- bone autografts (postoperative period, 1-24 months; mean, 5.2 months). Of the 40 studies performed in clinically stable knees (30 patients), MR demonstrated a well-defined, signal void ACL graft in 36. Of the three studies performed in three patients with clinical ACL laxity or suspected tear, the neoligament was of intermediate definition in one and nondiscernible in the other two. As in the native knee, buckling of the PCL was suggestive of ACL insufficiency. Bone tunnel placement, patellar tendon changes, and joint effusions were also evaluated

  11. Stochastic reconstruction of sandstones

    International Nuclear Information System (INIS)

    A simulated annealing algorithm is employed to generate a stochastic model for a Berea sandstone and a Fontainebleau sandstone, with each a prescribed two-point probability function, lineal-path function, and ''pore size'' distribution function, respectively. We find that the temperature decrease of the annealing has to be rather quick to yield isotropic and percolating configurations. A comparison of simple morphological quantities indicates good agreement between the reconstructions and the original sandstones. Also, the mean survival time of a random walker in the pore space is reproduced with good accuracy. However, a more detailed investigation by means of local porosity theory shows that there may be significant differences of the geometrical connectivity between the reconstructed and the experimental samples. (c) 2000 The American Physical Society

  12. Stochastic reconstruction of sandstones

    Science.gov (United States)

    Manwart; Torquato; Hilfer

    2000-07-01

    A simulated annealing algorithm is employed to generate a stochastic model for a Berea sandstone and a Fontainebleau sandstone, with each a prescribed two-point probability function, lineal-path function, and "pore size" distribution function, respectively. We find that the temperature decrease of the annealing has to be rather quick to yield isotropic and percolating configurations. A comparison of simple morphological quantities indicates good agreement between the reconstructions and the original sandstones. Also, the mean survival time of a random walker in the pore space is reproduced with good accuracy. However, a more detailed investigation by means of local porosity theory shows that there may be significant differences of the geometrical connectivity between the reconstructed and the experimental samples. PMID:11088546

  13. Reconstructing the Tengger calendar

    Directory of Open Access Journals (Sweden)

    Ian Proudfoot

    2008-12-01

    Full Text Available The survival of an Indic calendar among the Tengger people of the Brama highlands in east Java opens a window on Java’s calendar history. Its hybrid form reflects accommodations between this non-Muslim Javanese group and the increasingly dominant Muslim Javanese culture. Reconstruction is challenging because of this hybridity, because of inconsistencies in practice, and because the historical evidence is sketchy and often difficult to interpret.

  14. Reconstructing the Tengger calendar

    OpenAIRE

    Ian Proudfoot

    2008-01-01

    The survival of an Indic calendar among the Tengger people of the Brama highlands in east Java opens a window on Java’s calendar history. Its hybrid form reflects accommodations between this non-Muslim Javanese group and the increasingly dominant Muslim Javanese culture. Reconstruction is challenging because of this hybridity, because of inconsistencies in practice, and because the historical evidence is sketchy and often difficult to interpret.

  15. Reconstructing holographic quintessence

    OpenAIRE

    Zhang, Xin

    2006-01-01

    The holographic dark energy model is an attempt for probing the nature of dark energy within the framework of quantum gravity. The dimensionless parameter $c$ determines the main property of the holographic dark energy. With the choice of $c\\geq 1$, the holographic dark energy can be described completely by a quintessence scalar field. In this paper, we show this quintessential description of the holographic dark energy with $c\\geq 1$ and reconstruct the potential of the quintessence as well ...

  16. Stochastic reconstruction of sandstones

    OpenAIRE

    Manwart, C.; Torquato, S.; Hilfer, R.

    2000-01-01

    A simulated annealing algorithm is employed to generate a stochastic model for a Berea and a Fontainebleau sandstone with prescribed two-point probability function, lineal path function, and ``pore size'' distribution function, respectively. We find that the temperature decrease of the annealing has to be rather quick to yield isotropic and percolating configurations. A comparison of simple morphological quantities indicates good agreement between the reconstructions and the original sandston...

  17. Reconstruction of vaginal agenesis.

    Science.gov (United States)

    Ozkan, Ozlenen; Erman Akar, Münire; Ozkan, Omer; Doğan, N Utku

    2011-06-01

    Vaginal ageneses are by no means rare anomalies. Complete Mullerian agenesis is the most common reason for vaginal agenesis requiring reconstruction. Patients usually present with pain, hematocolpos, or hematometra in puberty, and later with amenorrhea and dyspareunia. Detailed information is given here regarding etiologies, timing of surgery, and current treatment options for vaginal agenesis. Outcomes and short- and long-term complications of recent treatment options are also discussed. PMID:21372677

  18. Orthotopic neobladder reconstruction

    OpenAIRE

    Chang, Dwayne T. S.; Nathan Lawrentschuk

    2015-01-01

    Orthotopic neobladder reconstruction is becoming an increasingly common urinary diversion following cystectomy for bladder cancer. This is in recognition of the potential benefits of neobladder surgery over creation of an ileal conduit related to quality of life (QoL), such as avoiding the need to form a stoma with its cosmetic, psychological and other potential complications. The PubMed database was searched using relevant search terms for articles published electronically between January 19...

  19. Canal Wall Reconstruction Mastoidectomy

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Objective To investigate the advantages of canal wall reconstruction (CWR) mastoidectomy, a single-stage technique for cholesteatoma removal and posterior external canal wall reconstruction, over the open and closed procedures in terms of cholesteatoma recurrence. Methods: Between June 2002 and December 2005, 38 patients (40 ears) with cholesteatoma were admited to Sun Yat-Sen Memorial Hospital and received surgical treatments. Of these patients, 25 were male with ages ranging between 11 and 60 years (mean = 31.6 years) and 13 were female with ages ranging between 20 and 65 years (mean = 38.8 years). Canal wall reconstruction (CWR)mastoidectomy was performed in 31 ears and canal wall down (CWD) mastoidectomy in 9 ears. Concha cartilage was used for ear canal wall reconstruction in 22 of the 31 CWR procedures and cortical mastoid bone was used in the remaining 9 cases. Results At 0.5 to 4 years follow up, all but one patients remained free of signs of cholesteatoma recurrence, i.e., no retraction pocket or cholesteatoma matrix. One patient, a smoker, needed revision surgery due to cholesteatoma recurrence 1.5 year after the initial operation. The recurrence rate was therefore 3.2% (1/31). Cholesteatoma recurrence was monitored using postoperative CT scans whenever possible. In the case that needed a revision procedure, a retraction pocket was identified by otoendoscopy in the pars flacida area that eventually evolved into a cholesteatoma. A pocket extending to the epitympanum filled with cholesteatoma matrix was confirmed during the revision operation, A decision to perform a modified mastoidectomy was made as the patient refused to quit smoking. The mean air-bone gap in pure tone threshold was 45 dB before surgery and 25 dB after (p < 0.05). There was no difference between using concha cartilage and cortical mastoid bone for the reconstruction regarding air-bone gap improvement, CT findings and otoendoscopic results. Conclusion CWR mastoidectomy can be used for

  20. Propagation phasor approach for holographic image reconstruction

    Science.gov (United States)

    Luo, Wei; Zhang, Yibo; Göröcs, Zoltán; Feizi, Alborz; Ozcan, Aydogan

    2016-01-01

    To achieve high-resolution and wide field-of-view, digital holographic imaging techniques need to tackle two major challenges: phase recovery and spatial undersampling. Previously, these challenges were separately addressed using phase retrieval and pixel super-resolution algorithms, which utilize the diversity of different imaging parameters. Although existing holographic imaging methods can achieve large space-bandwidth-products by performing pixel super-resolution and phase retrieval sequentially, they require large amounts of data, which might be a limitation in high-speed or cost-effective imaging applications. Here we report a propagation phasor approach, which for the first time combines phase retrieval and pixel super-resolution into a unified mathematical framework and enables the synthesis of new holographic image reconstruction methods with significantly improved data efficiency. In this approach, twin image and spatial aliasing signals, along with other digital artifacts, are interpreted as noise terms that are modulated by phasors that analytically depend on the lateral displacement between hologram and sensor planes, sample-to-sensor distance, wavelength, and the illumination angle. Compared to previous holographic reconstruction techniques, this new framework results in five- to seven-fold reduced number of raw measurements, while still achieving a competitive resolution and space-bandwidth-product. We also demonstrated the success of this approach by imaging biological specimens including Papanicolaou and blood smears. PMID:26964671

  1. Propagation phasor approach for holographic image reconstruction

    Science.gov (United States)

    Luo, Wei; Zhang, Yibo; Göröcs, Zoltán; Feizi, Alborz; Ozcan, Aydogan

    2016-03-01

    To achieve high-resolution and wide field-of-view, digital holographic imaging techniques need to tackle two major challenges: phase recovery and spatial undersampling. Previously, these challenges were separately addressed using phase retrieval and pixel super-resolution algorithms, which utilize the diversity of different imaging parameters. Although existing holographic imaging methods can achieve large space-bandwidth-products by performing pixel super-resolution and phase retrieval sequentially, they require large amounts of data, which might be a limitation in high-speed or cost-effective imaging applications. Here we report a propagation phasor approach, which for the first time combines phase retrieval and pixel super-resolution into a unified mathematical framework and enables the synthesis of new holographic image reconstruction methods with significantly improved data efficiency. In this approach, twin image and spatial aliasing signals, along with other digital artifacts, are interpreted as noise terms that are modulated by phasors that analytically depend on the lateral displacement between hologram and sensor planes, sample-to-sensor distance, wavelength, and the illumination angle. Compared to previous holographic reconstruction techniques, this new framework results in five- to seven-fold reduced number of raw measurements, while still achieving a competitive resolution and space-bandwidth-product. We also demonstrated the success of this approach by imaging biological specimens including Papanicolaou and blood smears.

  2. On Stack Reconstruction Problem

    Directory of Open Access Journals (Sweden)

    V. D. Аkeliev

    2014-06-01

    Full Text Available The paper describes analytical investigations that study relation of fuel combustion regimes with concentration values of sulphur anhydride in flue gases and acid dew point. Coefficients of convective heat transfer at internal and external surfaces of stacks have been determined in the paper. The paper reveals the possibility to reconstruct stacks while using gas discharging channel made of composite material on the basis of glass-reinforced plastic which permits to reduce thermo-stressed actions on reinforced concrete and increase volume of released gases due to practically two-fold reduction of gas-dynamic pressure losses along the pipe length.

  3. Evolutionary tree reconstruction

    Science.gov (United States)

    Cheeseman, Peter; Kanefsky, Bob

    1990-01-01

    It is described how Minimum Description Length (MDL) can be applied to the problem of DNA and protein evolutionary tree reconstruction. If there is a set of mutations that transform a common ancestor into a set of the known sequences, and this description is shorter than the information to encode the known sequences directly, then strong evidence for an evolutionary relationship has been found. A heuristic algorithm is described that searches for the simplest tree (smallest MDL) that finds close to optimal trees on the test data. Various ways of extending the MDL theory to more complex evolutionary relationships are discussed.

  4. Direct reconstruction of enhanced signal in computed tomography perfusion

    Science.gov (United States)

    Li, Bin; Lyu, Qingwen; Ma, Jianhua; Wang, Jing

    2016-04-01

    High imaging dose has been a concern in computed tomography perfusion (CTP) as repeated scans are performed at the same location of a patient. On the other hand, signal changes only occur at limited regions in CT acquired at different time points. In this work, we propose a new reconstruction strategy by effectively utilizing the initial phase high-quality CT to reconstruct the later phase CT acquired with a low-dose protocol. In the proposed strategy, initial high-quality CT is considered as a base image and enhanced signal (ES) is reconstructed directly by minimizing the penalized weighted least-square (PWLS) criterion. The proposed PWLS-ES strategy converts the conventional CT reconstruction into a sparse signal reconstruction problem. Digital and anthropomorphic phantom studies were performed to evaluate the performance of the proposed PWLS-ES strategy. Both phantom studies show that the proposed PWLS-ES method outperforms the standard iterative CT reconstruction algorithm based on the same PWLS criterion according to various quantitative metrics including root mean squared error (RMSE) and the universal quality index (UQI).

  5. Non-microsurgical breast reconstruction

    Directory of Open Access Journals (Sweden)

    Sharma Sheel

    2007-12-01

    Full Text Available Breast reconstruction after mastectomy should aim at resulting in an aesthetic outcome that matches the patient′s expectations and without interfering in the oncologic treatment. Whether the reconstruction is performed immediately or in a delayed fashion depends on various factors, which needs detailed attention. Autologous tissue, implants or both are used in the reconstruction. This article reviews the current concepts in these, with emphasis on non-microsurgical methods of using the autologous tissue for reconstruction. Breast conservation has become an accepted practice of treatment. Reconstruction in these situations as well as in an occasion when the surgery is done for failed breast conservation is discussed in detail. The article also reviews the various methods for nipple reconstruction available.

  6. Biomaterials for craniofacial reconstruction

    Directory of Open Access Journals (Sweden)

    Neumann, Andreas

    2009-01-01

    Full Text Available Biomaterials for reconstruction of bony defects of the skull comprise of osteosynthetic materials applied after osteotomies or traumatic fractures and materials to fill bony defects which result from malformation, trauma or tumor resections. Other applications concern functional augmentations for dental implants or aesthetic augmentations in the facial region.For ostheosynthesis, mini- and microplates made from titanium alloys provide major advantages concerning biocompatibility, stability and individual fitting to the implant bed. The necessity of removing asymptomatic plates and screws after fracture healing is still a controversial issue. Risks and costs of secondary surgery for removal face a low rate of complications (due to corrosion products when the material remains in situ. Resorbable osteosynthesis systems have similar mechanical stability and are especially useful in the growing skull.The huge variety of biomaterials for the reconstruction of bony defects makes it difficult to decide which material is adequate for which indication and for which site. The optimal biomaterial that meets every requirement (e.g. biocompatibility, stability, intraoperative fitting, product safety, low costs etc. does not exist. The different material types are (autogenic bone and many alloplastics such as metals (mainly titanium, ceramics, plastics and composites. Future developments aim to improve physical and biological properties, especially regarding surface interactions. To date, tissue engineered bone is far from routine clinical application.

  7. LHCb; LHCb Jet Reconstruction

    CERN Multimedia

    Augusto, O

    2012-01-01

    The Large Hadron Collider (LHC) is the most powerful particle accelerator in the world. It has been designed to collide proton beams at an energy up to 14 TeV in the center of mass. In 2011, the data taking was done with a center of mass energy of 7 TeV, the instant luminosity has reached values greater than $4 \\times 10^{32} cm^{-2} s^{-1}$ and the integrated luminosity reached the value of 1.02 $fb^{-1}$ on the LHCb. The jet reconstruction is fundamental to observe events that can be used to test pertubative QCD (pQCD). It also provides a way to observe standard model channels and searches for new physics like SUSY. The anti-kt algorithm is a jet reconstruction algorithm that is based on the distance of the particles on the space $\\eta \\times \\phi$ and on the transverse momentum of particles. To maximize the energy resolution all information about the trackers and the calo...

  8. Delayed breast implant reconstruction

    DEFF Research Database (Denmark)

    Hvilsom, Gitte B.; Hölmich, Lisbet R.; Steding-Jessen, Marianne;

    2012-01-01

    We evaluated the association between radiation therapy and severe capsular contracture or reoperation after 717 delayed breast implant reconstruction procedures (288 1- and 429 2-stage procedures) identified in the prospective database of the Danish Registry for Plastic Surgery of the Breast during...... the period between 1999 and 2006. A history of radiation therapy was associated with increased risk of severe capsular contracture for 1- and 2-stage procedures, with adjusted hazard ratios (HR) of 3.3 (95% confidence interval [CI]: 0.9-12.4) and 7.2 (95% CI: 2.4-21.4), respectively. Similarly, a...... history of radiation therapy was associated with a non-significantly increased risk of reoperation after both 1-stage (HR = 1.4; 95% CI: 0.7-2.5) and 2-stage (HR = 1.6; 95% CI: 0.9-3.1) procedures. Reconstruction failure was highest (13.2%) in the 2-stage procedures with a history of radiation therapy...

  9. Reconstructing Experiences through Sketching

    CERN Document Server

    Karapanos, Evangelos; Hassenzahl, Marc

    2009-01-01

    This paper presents iScale, a survey tool that aims at eliciting users' experiences with a product from memory. iScale employs sketching in imposing a process in the reconstruction of one's experiences. Two versions of iScale, the Constructive and the Value-Account iScale, were motivated by two distinct theories on how people reconstruct emotional experiences from memory. These two versions were tested in two separate studies. Study 1 aimed at providing qualitative insight into the use of iScale and compared its performance to that of free-hand sketching. Study 2 compared the two iScale versions to a control condition: that of reporting one's experiences without employing any form of sketching. Significant differences between iScale and the "no-sketching" tool were found. Overall, iScale resulted in a) an increase in the number of experience reports that subjects provided, b) an increase in the amount of contextual information for the reported experiences, and c) an increase in subjects' accuracy in recalling...

  10. Three-dimensional ICT reconstruction

    International Nuclear Information System (INIS)

    The three-dimensional ICT reconstruction method is the hot topic of recent ICT technology research. In the context, qualified visual three-dimensional ICT pictures are achieved through multi-piece two-dimensional images accumulation by, combining with thresholding method and linear interpolation. Different direction and different position images of the reconstructed pictures are got by rotation and interception respectively. The convenient and quick method is significantly instructive to more complicated three-dimensional reconstruction of ICT images. (authors)

  11. Reconstruction of symmetric Potts Models

    OpenAIRE

    Sly, Allan

    2008-01-01

    The reconstruction problem on the tree has been studied in numerous contexts including statistical physics, information theory and computational biology. However, rigorous reconstruction thresholds have only been established in a small number of models. We prove the first exact reconstruction threshold in a non-binary model establishing the Kesten-Stigum bound for the 3-state Potts model on regular trees of large degree. We further establish that the Kesten-Stigum bound is not tight for the $...

  12. Unfavourable results in thumb reconstruction

    Directory of Open Access Journals (Sweden)

    Samir M Kumta

    2013-01-01

    Full Text Available The history of thumb reconstruction parallels the history of hand surgery. The attributes that make the thumb unique, and that the reconstructive surgeon must assess and try to restore when reconstructing a thumb, are: Position, stability, strength, length, motion, sensibility and appearance. Deficiency in any of these attributes can reduce the utility of the reconstructed thumb. A detailed assessment of the patient and his requirements needs to be performed before embarking on a thumb reconstruction. Most unsatisfactory results can be attributed to wrong choice of procedure. Component defects of the thumb are commonly treated by tissue from adjacent fingers, hand or forearm. With refinements in microsurgery, the foot has become a major source of tissue for component replacement in the thumb. Bone lengthening, osteoplastic reconstruction, pollicisation, and toe to hand transfers are the commonest methods of thumb reconstruction. Unfavourable results can be classified as functional and aesthetic. Some are common to all types of procedures. However each type of reconstruction has its own unique set of problems. Meticulous planning and execution is essential to give an aesthetic and functionally useful thumb. Secondary surgeries like tendon transfers, bone grafting, debulking, arthrodesis, may be required to correct deficiencies in the reconstruction. Attention needs to be paid to the donor site as well.

  13. Set Reconstruction on the Hypercube

    OpenAIRE

    Pebody, Luke

    2016-01-01

    Given an action of a group $G$ on a set $S$, the $k$-deck of a subset $T$ of $S$ is the multiset of all subsets of $T$ of size $k$, each given up to translation by $G$. For a given subset $T$, the {\\em reconstruction number} of $T$ is the minimum $k$ such that the $k$-deck uniquely identifies $T$ up to translation by $G$, and the {\\em reconstruction number} of the action $G:S$ is the maximum reconstruction number of any subset of $S$. The concept of reconstruction number extends naturally to ...

  14. Virtual 3-D Facial Reconstruction

    Directory of Open Access Journals (Sweden)

    Martin Paul Evison

    2000-06-01

    Full Text Available Facial reconstructions in archaeology allow empathy with people who lived in the past and enjoy considerable popularity with the public. It is a common misconception that facial reconstruction will produce an exact likeness; a resemblance is the best that can be hoped for. Research at Sheffield University is aimed at the development of a computer system for facial reconstruction that will be accurate, rapid, repeatable, accessible and flexible. This research is described and prototypical 3-D facial reconstructions are presented. Interpolation models simulating obesity, ageing and ethnic affiliation are also described. Some strengths and weaknesses in the models, and their potential for application in archaeology are discussed.

  15. Beam tomography in transverse normalised phase space

    International Nuclear Information System (INIS)

    We demonstrate that the normalised phase space can be used to improve the quality of the reconstructed image in phase space tomography. This study uses the Filtered Back Projection (FBP) for reconstruction. We simulate the tomographic projections of a Gaussian phase space distribution in real phase space and in normalised phase space. The reconstruction can be carried out in real phase space directly. It can also be done first in normalised phase space, and then the co-ordinates can be transformed to real phase space. Using FBP, we show that the latter procedure produces images that agree well with the original distribution even when there are only three angles. It also gives better resolution for a more complex distribution, which we simulate with a random collection of Gaussian spots.

  16. Improved Maneuver Reconstructions for the GRAIL Orbiters

    Science.gov (United States)

    Keck, Mason; You, Tung-Han; Antreasian, Peter

    2012-01-01

    Maneuver reconstructions for the Gravity Recovery and Interior Laboratory (GRAIL) A and B lunar orbiters were improved through updates to the orbit determination filter and dynamic models. Consistent reconstructions of the 27 GRAIL A and B maneuvers from the Trans-Lunar Cruise phase in the fall of 2011 through the Transition to Science Formation phase in February 2012 were performed. Standard methods of orbit determination were applied incorporating the latest dynamic models and filter strategies developed by the GRAIL Navigation and Science Teams, including a high resolution, 420 x 420 degree and order lunar spherical harmonic gravity field model. For Trans-Lunar Cruise for GRAIL-A (TLC-A), all maneuvers executed with delta V errors below 5.50 +/- 0.50 mm/s and pointing errors below 0.25 degrees. GRAIL-A lunar orbit maneuvers had delta V errors below 30.0 mm/s and pointing errors below 0.51 degrees. For TLC-B, all maneuvers executed with delta V errors below 8.60 +/- 1.41 mm/s and pointing errors below 0.300 degrees. GRAIL-B maneuvers in lunar orbit executed with maximum delta V errors of 25.0 mm/s and pointing error of 0.43 degrees. These maneuver reconstructions will enable the GRAIL Navigation Team to better characterize the main engine performance of each spacecraft. This will help the Navigation Team to navigate low (greater than 8 km) altitude orbits during the extended mission phase in the fall of 2012.

  17. Displacement disorder and reconstruction of the (001) face of tungsten

    International Nuclear Information System (INIS)

    The reconstruction of the (001) border of tungsten is examined taking into consideration random static displacements of surface atoms in the high-temperature (1 x 1) phase. A microscopic model is proposed, in which the creation of c(2 x 2) phase is described as a transition of the Jahn-Teller type and an ordering of static displacements. It is shown that displacement disorder induces instability of (001) tungsten with respect to reconstruction. The effect of a uniform electric field on a disordered reconstructing surface is examined. A possible reason is given for pronounced differences in the results of investigations of the structural conversion of the (001) face in tungsten when different experimental methods are used

  18. Optimal reconstruction angles

    International Nuclear Information System (INIS)

    The question of optimal projection angles has recently become of interest in the field of reconstruction from projections. Here, studies are concentrated on the n x n pixel space, where literative algorithms such as ART and direct matrix techniques due to Katz are considered. The best angles are determined in a Gauss--Markov statistical sense as well as with respect to a function-theoretical error bound. The possibility of making photon intensity a function of angle is also examined. Finally, the best angles to use in an ART-like algorithm are studied. A certain set of unequally spaced angles was found to be preferred in several contexts. 15 figures, 6 tables

  19. Urogenital Reconstructive Surgery

    DEFF Research Database (Denmark)

    Jakobsen, Lotte Kaasgaard

    the lower urinary tract causes voiding disabilities, renal failure and chronic bladder changes. Children with such malformations often require extensive treatment, and will experience side effects and not always satisfactory results. Aim: To develop an animal model of congenital infravesical......Urogenital reconstructive surgery Lotte Kaasgaard Jakobsen1 Professor Henning Olsen1 Overlæge Gitte Hvistendahl1 Professor Karl-Erik Andersson2 1 – Dept. of Urology, Aarhus University Hospital 2 – Dept. of Gynecology and Obstetrics, Aarhus University hospital Background: Congenital obstruction of...... the fetal bladder to those of the bladder from young pigs used in the animal model. Results: By further characterising the effect of congenital obstruction, regarding urodynamic properties of the bladder and structural changes in the bladder tissue and comparing the results after relief of obstruction...

  20. PSF reconstruction for NAOS-CONICA

    CERN Document Server

    Clénet, Y; Gendron, E; Fusco, T; Rousset, G; Gratadour, D; Lidman, C; Marco, O; Ageorges, N; Egner, S; Cl\\'{e}net, Yann; Kasper, Markus; Gendron, Eric; Fusco, Thierry; Gratadour, Damien; Lidman, Christopher; Marco, Olivier; Ageorges, Nancy; Egner, Sebastian

    2006-01-01

    Adaptive optics (AO) allows one to derive the point spread function (PSF) simultaneously to the science image, which is a major advantage in post-processing tasks such as astrometry/photometry or deconvolution. Based on the algorithm of \\citet{veran97}, PSF reconstruction has been developed for four different AO systems so far: PUEO, ALFA, Lick-AO and Altair. A similar effort is undertaken for NAOS/VLT in a collaboration between the group PHASE (Onera and Observatoire de Paris/LESIA) and ESO. In this paper, we first introduce two new algorithms that prevent the use of the so-called "$U\\_{ij}$ functions" to: (1) avoid the storage of a large amount of data (for both new algorithms), (2) shorten the PSF reconstruction computation time (for one of the two) and (3) provide an estimation of the PSF variability (for the other one). We then identify and explain issues in the exploitation of real-time Shack-Hartmann (SH) data for PSF reconstruction, emphasising the large impact of thresholding in the accuracy of the p...

  1. An approach to prior austenite reconstruction

    International Nuclear Information System (INIS)

    One area of interest in Friction Stir Welding (FSW) of steels is to understand microstructural evolution during the process. Most of the deformation occurs in the austenite temperature range. Quantitative microstructural measurements of prior austenite microstructure are needed in order to understand evolution of the microstructure. Considering the fact that room temperature microstructure in ferritic steels contains very little to no retained austenite, prior austenite microstructure needs to be recovered from the room temperature ferrite. In this paper, an approach based on Electron Backscattered Diffraction (EBSD) is introduced to detect Bain zones. Bain zone detection is used to reconstruct prior austenite grain structure. Additionally, a separate approach based on phase transformation orientation relationships is introduced in order to recover prior austenite orientation. - Highlights: ►This approach provides a tool to reconstruct large-scale austenite microstructures. ► It recovers prior austenite orientation without relying on retained austenite. ► It utilizes EBSD data from the room temperature microstructure. ► Higher number of active variants leads to more accurate reconstructions. ► At least two variants are needed in order to recover prior austenite orientation.

  2. Reconstructing the Alcatraz escape

    Science.gov (United States)

    Baart, F.; Hoes, O.; Hut, R.; Donchyts, G.; van Leeuwen, E.

    2014-12-01

    In the night of June 12, 1962 three inmates used a raft made of raincoatsto escaped the ultimate maximum security prison island Alcatraz in SanFrancisco, United States. History is unclear about what happened tothe escapees. At what time did they step into the water, did theysurvive, if so, where did they reach land? The fate of the escapees has been the subject of much debate: did theymake landfall on Angel Island, or did the current sweep them out ofthe bay and into the cold pacific ocean? In this presentation, we try to shed light on this historic case using avisualization of a high-resolution hydrodynamic simulation of the San Francisco Bay, combined with historical tidal records. By reconstructing the hydrodynamic conditions and using a particle based simulation of the escapees we show possible scenarios. The interactive model is visualized using both a 3D photorealistic and web based visualization. The "Escape from Alcatraz" scenario demonstrates the capabilities of the 3Di platform. This platform is normally used for overland flooding (1D/2D). The model engine uses a quad tree structure, resulting in an order of magnitude speedup. The subgrid approach takes detailed bathymetry information into account. The inter-model variability is tested by comparing the results with the DFlow Flexible Mesh (DFlowFM) San Francisco Bay model. Interactivity is implemented by converting the models from static programs to interactive libraries, adhering to the Basic ModelInterface (BMI). Interactive models are more suitable for answeringexploratory research questions such as this reconstruction effort. Although these hydrodynamic simulations only provide circumstantialevidence for solving the mystery of what happened during the foggy darknight of June 12, 1962, it can be used as a guidance and provides aninteresting testcase to apply interactive modelling.

  3. Gender Mainstreaming and Sustainable Post Disaster Reconstruction,

    OpenAIRE

    Yumarni, Tri; Amaratunga, Dilanthi; Haigh, Richard

    2013-01-01

    Gender inequalities are barriers to achieve sustainable post disaster reconstruction. Mainstreaming gender equality within post disaster reconstruction process can enhance sustainability of reconstruction. Based on a detailed literature review on post disaster reconstruction, this paper identifies pre-requisite conditions for mainstreaming gender within sustainable post disaster reconstruction as ; awareness of gender needs and concerns, a strong gender policy framework, women ...

  4. Use of three-dimensional time-resolved phase-contrast magnetic resonance imaging with vastly undersampled isotropic projection reconstruction to assess renal blood flow in a renal cell carcinoma patient treated with sunitinib: a case report

    OpenAIRE

    Takayama, Tatsuya; Takehara, Yasuo; Sugiyama, Masataka; Sugiyama, Takayuki; Ishii, Yasuo; Johnson, Kevin E; Wieben, Oliver; Wakayama, Tetsuya; Sakahara, Harumi; Ozono, Seiichiro

    2014-01-01

    Background New imaging modalities to assess the efficacy of drugs that have molecular targets remain under development. Here, we describe for the first time the use of time-resolved three-dimensional phase-contrast magnetic resonance imaging to monitor changes in blood supply to a tumor during sunitinib treatment in a patient with localized renal cell carcinoma. Case presentation A 43-year-old Japanese woman with a tumor-bearing but functional single kidney presented at our hospital in July 2...

  5. Registration-based Reconstruction of Four-dimensional Cone Beam Computed Tomography

    DEFF Research Database (Denmark)

    Christoffersen, Christian; Hansen, David Christoffer; Poulsen, Per Rugaard; Sørensen, Thomas Sangild

    2013-01-01

    We present a new method for reconstruction of four-dimensional (4D) cone beam computed tomography from an undersampled set of X-ray projections. The novelty of the proposed method lies in utilizing optical flow based registration to facilitate that each temporal phase is reconstructed from the full...

  6. On a reconstruction algorithm for the trajectory and control in a delay system

    OpenAIRE

    Blizorukova, M. S.; V.I. Maksimov

    2013-01-01

    We discuss a problem of the dynamic reconstruction of unmeasured coordinates of the phase vector and unknown controls in nonlinear vector equations with delay. A regularizing algorithm is proposed for the reconstruction of both controls and unmeasured coordinates simultaneously with the processes. The algorithm is stable with respect to information noises and computational errors. © 2013 Pleiades Publishing, Ltd.

  7. Breast reconstruction - methods and imaging

    International Nuclear Information System (INIS)

    Silicon implants are used for breast reconstruction or for cosmetic operations. The contribution outlines the role of mammography, sonography and MR for defect assessment, tumour detection and monitoring after prosthesis implantation. Instrument adjustment for mammographic screening of patients with implants is gone into. Autologic reconstruction techniques and protocols of secondary and tertiary early detection are presented. (orig.)

  8. Markov Random Field Surface Reconstruction

    DEFF Research Database (Denmark)

    Paulsen, Rasmus Reinhold; Bærentzen, Jakob Andreas; Larsen, Rasmus

    2010-01-01

    A method for implicit surface reconstruction is proposed. The novelty in this paper is the adaption of Markov Random Field regularization of a distance field. The Markov Random Field formulation allows us to integrate both knowledge about the type of surface we wish to reconstruct (the prior) and...

  9. Martensitic phase transitions

    Energy Technology Data Exchange (ETDEWEB)

    Petry, W.; Neuhaus, J. [Techn. Universitaet Muenchen, Physik Department E13, Munich (Germany)

    1996-11-01

    Many elements transform from a high temperature bcc phase to a more dense packed temperature phase. The great majority of these transitions are of 1st order, displacive and reconstructive. The lattice potentials which govern these martensitic transitions can be probed by inelastic neutron scattering, thereby answering fundamental questions like : Will the transition be announced by dynamical or static fluctuations? What are the trajectories for the displacements needed for the transformation? Does the vibrational entropy stabilize the high temperature phase? Are the unusual transport properties in these materials related to their ability to transform? (author) 17 figs., 1 tab., 46 refs.

  10. Simultaneous segmentation and reconstruction: A level set method approach for limited view computed tomography

    International Nuclear Information System (INIS)

    Purpose: An iterative tomographic reconstruction algorithm that simultaneously segments and reconstructs the reconstruction domain is proposed and applied to tomographic reconstructions from a sparse number of projection images. Methods: The proposed algorithm uses a two-phase level set method segmentation in conjunction with an iterative tomographic reconstruction to achieve simultaneous segmentation and reconstruction. The simultaneous segmentation and reconstruction is achieved by alternating between level set function evolutions and per-region intensity value updates. To deal with the limited number of projections, a priori information about the reconstruction is enforced via penalized likelihood function. Specifically, smooth function within each region (piecewise smooth function) and bounded function intensity values for each region are assumed. Such a priori information is formulated into a quadratic objective function with linear bound constraints. The level set function evolutions are achieved by artificially time evolving the level set function in the negative gradient direction; the intensity value updates are achieved by using the gradient projection conjugate gradient algorithm. Results: The proposed simultaneous segmentation and reconstruction results were compared to ''conventional'' iterative reconstruction (with no segmentation), iterative reconstruction followed by segmentation, and filtered backprojection. Improvements of 6%-13% in the normalized root mean square error were observed when the proposed algorithm was applied to simulated projections of a numerical phantom and to real fan-beam projections of the Catphan phantom, both of which did not satisfy the a priori assumptions. Conclusions: The proposed simultaneous segmentation and reconstruction resulted in improved reconstruction image quality. The algorithm correctly segments the reconstruction space into regions, preserves sharp edges between different regions, and smoothes the noise

  11. TOLLAN-XICOCOTITLAN: A RECONSTRUCTED CITY BY AUGMENTED REALITY (EXTENDED

    Directory of Open Access Journals (Sweden)

    M. en C. Martha Rosa Cordero López

    2014-10-01

    Full Text Available Work In Terminal presents the analysis, design, implementation and results of Reconstruction Xicocotitlan Tollan-through augmented reality (Extended, which will release information about the Toltec capital supplemented by presenting an overview of the main premises of the Xicocotitlan Tollan city supported dimensional models based on the augmented reality technique showing the user a virtual representation of buildings in Tollan phase.

  12. RECONSTRUCTION OF TOLLANXICOCOTITLAN CITY BY AUGMENTED REALITY (EXTENDED

    Directory of Open Access Journals (Sweden)

    M. en C. Martha Rosa Cordero Lopez

    2014-05-01

    Full Text Available Work In Terminal presents the analysis, design, implementation and results of Reconstruction Xicocotitlan Tollan-through augmented reality (Extended, which will release information about the Toltec capital supplemented by presenting an overview of the main premises of the Xicocotitlan Tollan city supported dimensional models based on the augmented reality technique showing the user a virtual representation of buildings in Tollan phase.

  13. On combination of the processes of reconstruction and guaranteeing control

    OpenAIRE

    Kryazhimskii, A. V.; V.I. Maksimov

    2013-01-01

    Consideration was given to the problem of controlling a system of ordinary differential equations under incomplete information about the phase states. Given was an algorithm to solve it on the basis of a combination of the "real-time" reconstruction processes and feedback control. © 2013 Pleiades Publishing, Ltd.

  14. Blob-enhanced reconstruction technique

    Science.gov (United States)

    Castrillo, Giusy; Cafiero, Gioacchino; Discetti, Stefano; Astarita, Tommaso

    2016-09-01

    A method to enhance the quality of the tomographic reconstruction and, consequently, the 3D velocity measurement accuracy, is presented. The technique is based on integrating information on the objects to be reconstructed within the algebraic reconstruction process. A first guess intensity distribution is produced with a standard algebraic method, then the distribution is rebuilt as a sum of Gaussian blobs, based on location, intensity and size of agglomerates of light intensity surrounding local maxima. The blobs substitution regularizes the particle shape allowing a reduction of the particles discretization errors and of their elongation in the depth direction. The performances of the blob-enhanced reconstruction technique (BERT) are assessed with a 3D synthetic experiment. The results have been compared with those obtained by applying the standard camera simultaneous multiplicative reconstruction technique (CSMART) to the same volume. Several blob-enhanced reconstruction processes, both substituting the blobs at the end of the CSMART algorithm and during the iterations (i.e. using the blob-enhanced reconstruction as predictor for the following iterations), have been tested. The results confirm the enhancement in the velocity measurements accuracy, demonstrating a reduction of the bias error due to the ghost particles. The improvement is more remarkable at the largest tested seeding densities. Additionally, using the blobs distributions as a predictor enables further improvement of the convergence of the reconstruction algorithm, with the improvement being more considerable when substituting the blobs more than once during the process. The BERT process is also applied to multi resolution (MR) CSMART reconstructions, permitting simultaneously to achieve remarkable improvements in the flow field measurements and to benefit from the reduction in computational time due to the MR approach. Finally, BERT is also tested on experimental data, obtaining an increase of the

  15. AORTOILIAC AND AORTOFEMORAL RECONSTRUCTION OF OBSTRUCTIVE DISEASE

    NARCIS (Netherlands)

    VANDENAKKER, PJ; VANSCHILFGAARDE, R; BRAND, R; VANBOCKEL, JH; TERPSTRA, JL

    1994-01-01

    This retrospective study evaluates our strategy to limit prosthetic reconstructions for aortoiliac obstructive disease to the diseased segments in 518 patients. There were 363 (70%) reconstructions without femoral anastomotic sites (FEM-0), 107 (21%) reconstructions with one femoral anastomotic site

  16. Prospects of linear reconstruction in atomic resolution electron holographic tomography

    International Nuclear Information System (INIS)

    Tomography commonly requires a linear relation between the measured signal and the underlying specimen property; for Electron Holographic Tomography this is given by the Phase Grating Approximation (PGA). While largely valid at medium resolution, discrepancies arise at high resolution imaging conditions. We set out to investigate the artefacts that are produced if the reconstruction still assumes the PGA even with an atomic resolution tilt series. To forego experimental difficulties the holographic tilt series was simulated. The reconstructed electric potential clearly shows peaks at the positions of the atoms. These peaks have characterisitic deformations, which can be traced back to the defocus a particular atom has in the holograms of the tilt series. Exchanging an atom for one of a different atomic number results in a significant change in the reconstructed potential that is well contained within the atom's peak. - Highlights: • We simulate a holographic tilt series of a nanocrystal with atomic resolution. • Using PGA-based Holographic Tomography we reconstruct the atomic structure. • The reconstruction shows characteristic artefacts, chiefly caused by defocus. • Changing one atom's Z produces a well localised in the reconstruction

  17. Semantically Documenting Virtual Reconstruction: Building a Path to Knowledge Provenance

    Science.gov (United States)

    Bruseker, G.; Guillem, A.; Carboni, N.

    2015-08-01

    The outcomes of virtual reconstructions of archaeological monuments are not just images for aesthetic consumption but rather present a scholarly argument and decision making process. They are based on complex chains of reasoning grounded in primary and secondary evidence that enable a historically probable whole to be reconstructed from the partial remains left in the archaeological record. This paper will explore the possibilities for documenting and storing in an information system the phases of the reasoning, decision and procedures that a modeler, with the support of an archaeologist, uses during the virtual reconstruction process and how they can be linked to the reconstruction output. The goal is to present a documentation model such that the foundations of evidence for the reconstructed elements, and the reasoning around them, are made not only explicit and interrogable but also can be updated, extended and reused by other researchers in future work. Using as a case-study the reconstruction of a kitchen in a Roman domus in Grand, we will examine the necessary documentation requirements, and the capacity to express it using semantic technologies. For our study we adopt the CIDOC-CRM ontological model, and its extensions CRMinf, CRMBa and CRMgeo as a starting point for modelling the arguments and relations.

  18. Prospects of linear reconstruction in atomic resolution electron holographic tomography

    Energy Technology Data Exchange (ETDEWEB)

    Krehl, Jonas, E-mail: Jonas.Krehl@triebenberg.de; Lubk, Axel

    2015-03-15

    Tomography commonly requires a linear relation between the measured signal and the underlying specimen property; for Electron Holographic Tomography this is given by the Phase Grating Approximation (PGA). While largely valid at medium resolution, discrepancies arise at high resolution imaging conditions. We set out to investigate the artefacts that are produced if the reconstruction still assumes the PGA even with an atomic resolution tilt series. To forego experimental difficulties the holographic tilt series was simulated. The reconstructed electric potential clearly shows peaks at the positions of the atoms. These peaks have characterisitic deformations, which can be traced back to the defocus a particular atom has in the holograms of the tilt series. Exchanging an atom for one of a different atomic number results in a significant change in the reconstructed potential that is well contained within the atom's peak. - Highlights: • We simulate a holographic tilt series of a nanocrystal with atomic resolution. • Using PGA-based Holographic Tomography we reconstruct the atomic structure. • The reconstruction shows characteristic artefacts, chiefly caused by defocus. • Changing one atom's Z produces a well localised in the reconstruction.

  19. STATISTICAL ANALYSIS OF TOMOGRAPHIC RECONSTRUCTION ALGORITHMS BY MORPHOLOGICAL IMAGE CHARACTERISTICS

    Directory of Open Access Journals (Sweden)

    Sebastian Lǖck

    2011-05-01

    Full Text Available We suggest a procedure for quantitative quality control of tomographic reconstruction algorithms. Our task-oriented evaluation focuses on the correct reproduction of phase boundary length and has thus a clear implication for morphological image analysis of tomographic data. Indirectly the method monitors accurate reproduction of a variety of locally defined critical image features within tomograms such as interface positions and microstructures, debonding, cracks and pores. Tomographic errors of such local nature are neglected if only global integral characteristics such as mean squared deviation are considered for the evaluation of an algorithm. The significance of differences in reconstruction quality between algorithms is assessed using a sample of independent random scenes to be reconstructed. These are generated by a Boolean model and thus exhibit a substantial stochastic variability with respect to image morphology. It is demonstrated that phase boundaries in standard reconstructions by filtered backprojection exhibit substantial errors. In the setting of our simulations, these could be significantly reduced by the use of the innovative reconstruction algorithm DIRECTT.

  20. Practical algorithms for simulation and reconstruction of digital in-line holograms

    CERN Document Server

    Latychevskaia, Tatiana

    2014-01-01

    Here, we present practical methods for simulation and reconstruction of in-line digital holograms recorded with plane and spherical waves. The algorithms described here are applicable to holographic imaging of an object exhibiting absorption as well as phase shifting properties. Optimal parameters, related to distances, sampling rate, and other factors for successful simulation and reconstruction of holograms are evaluated and criteria for the achievable resolution are worked out. Moreover, we show that the numerical procedures for the reconstruction of holograms recorded with plane and spherical waves are identical under certain conditions. Experimental examples of holograms and their reconstructions are also discussed.

  1. Re-sampling of inline holographic images for improved reconstruction resolution

    CERN Document Server

    Podorov, S G; Paganin, D M; Pavlov, K M

    2009-01-01

    Digital holographic microscopy based on Gabor in-line holography is a well-known method to reconstruct both the amplitude and phase of small objects. To reconstruct the image of an object from its hologram, obtained under illumination by monochromatic scalar waves, numerical calculations of Fresnel integrals are required. To improve spatial resolution in the resulting reconstruction, we re-sample the holographic data before application of the reconstruction algorithm. This procedure amounts to inverting an interpolated Fresnel diffraction image to recover the object. The advantage of this method is demonstrated on experimental data, for the case of visible-light Gabor holography of a resolution grid and a gnat wing.

  2. Vulvovaginal reconstruction for neoplastic disease.

    Science.gov (United States)

    Höckel, Michael; Dornhöfer, Nadja

    2008-06-01

    Current treatment of neoplastic disease that involves the external female genitalia aims to achieve local disease control, but not to restore form and function of these organs. Despite a growing trend to reduce the extent of surgical resection, impaired quality of life after surgery due to severe sexual dysfunction and disturbed body image is common. We postulate that the integration of surgical techniques for vulvar and vaginal reconstruction into primary treatment would improve aesthetic and functional results and therefore quality of life. We systematically searched the literature for surgical procedures designed and validated for vulvovaginal reconstruction. Various skin flaps, both with random vascularisation and those based on vascular territories (ie, axial pattern, fasciocutaneous, musculocutaneous, and bowel flaps), can restore important parts of vulvovaginal form and function with acceptable morbidity at the donor and recipient sites. Appropriate vulvovaginal reconstruction cannot be achieved by doing a few standardised procedures; rather, it necessitates specialists who are familiar with general principles of reconstructive surgery to master many techniques to select the optimum procedure for the individual patient. Vulvovaginal reconstructive surgery has limitations, particularly achievement of functional restoration in irradiated tissue. Physicians who treat women with neoplastic disease of the external genitalia should be aware of the current state of vulvovaginal reconstructive surgery. Prospective controlled clinical trials are warranted to assess the effect of vulvovaginal reconstruction on morbidity and quality of life after treatment. PMID:18510987

  3. Evidence-Based ACL Reconstruction

    Directory of Open Access Journals (Sweden)

    E. Carlos RODRIGUEZ-MERCHAN

    2015-01-01

    Full Text Available There is controversy in the literature regarding a number of topics related to anterior cruciate ligament (ACLreconstruction. The purpose of this article is to answer the following questions: 1 Bone patellar tendon bone (BPTB reconstruction or hamstring reconstruction (HR; 2 Double bundle or single bundle; 3 Allograft or authograft; 4 Early or late reconstruction; 5 Rate of return to sports after ACL reconstruction; 6 Rate of osteoarthritis after ACL reconstruction. A Cochrane Library and PubMed (MEDLINE search of systematic reviews and meta-analysis related to ACL reconstruction was performed. The key words were: ACL reconstruction, systematic reviews and meta-analysis. The main criteria for selection were that the articles were systematic reviews and meta-analysesfocused on the aforementioned questions. Sixty-nine articles were found, but only 26 were selected and reviewed because they had a high grade (I-II of evidence. BPTB-R was associated with better postoperative knee stability but with a higher rate of morbidity. However, the results of both procedures in terms of functional outcome in the long-term were similar. The double-bundle ACL reconstruction technique showed better outcomes in rotational laxity, although functional recovery was similar between single-bundle and double-bundle. Autograft yielded better results than allograft. There was no difference between early and delayed reconstruction. 82% of patients were able to return to some kind of sport participation. 28% of patients presented radiological signs of osteoarthritis with a follow-up of minimum 10 years.

  4. Facial Reconstruction and Rehabilitation.

    Science.gov (United States)

    Guntinas-Lichius, Orlando; Genther, Dane J; Byrne, Patrick J

    2016-01-01

    Extracranial infiltration of the facial nerve by salivary gland tumors is the most frequent cause of facial palsy secondary to malignancy. Nevertheless, facial palsy related to salivary gland cancer is uncommon. Therefore, reconstructive facial reanimation surgery is not a routine undertaking for most head and neck surgeons. The primary aims of facial reanimation are to restore tone, symmetry, and movement to the paralyzed face. Such restoration should improve the patient's objective motor function and subjective quality of life. The surgical procedures for facial reanimation rely heavily on long-established techniques, but many advances and improvements have been made in recent years. In the past, published experiences on strategies for optimizing functional outcomes in facial paralysis patients were primarily based on small case series and described a wide variety of surgical techniques. However, in the recent years, larger series have been published from high-volume centers with significant and specialized experience in surgical and nonsurgical reanimation of the paralyzed face that have informed modern treatment. This chapter reviews the most important diagnostic methods used for the evaluation of facial paralysis to optimize the planning of each individual's treatment and discusses surgical and nonsurgical techniques for facial rehabilitation based on the contemporary literature. PMID:27093062

  5. Reconstructing human evolution

    CERN Document Server

    Cavalli-Sforza, M

    1999-01-01

    One can reconstruct human evolution using modern genetic data and models based on the mathematical theory of evolution and its four major factors : mutation, natural selection, statistical fluctuations in finite populations (random genetic drift), and migration. Archaeology gives some help on the major dates and events of the process. Chances of studying ancient DNA are very limited but there have been a few successful results. Studying DNA instead of proteins, as was done until a few years ago, and in particular the DNA of mitochondria and of the Y chromosome which are transmitted, respectively, by the maternal line and the paternal line, has greatly simplified the analysis. It is now possible to carry the analysis on individuals, while earlier studies were of necessity based on populations. Also the evolution of ÒcultureÓ (i.e. what we learn from others), in particular that of languages, gives some help and can be greatly enlightened by genetic studies. Even though it is largely based on mechanisms of mut...

  6. Orthotopic neobladder reconstruction

    Directory of Open Access Journals (Sweden)

    Dwayne T. S. Chang

    2015-01-01

    Full Text Available Orthotopic neobladder reconstruction is becoming an increasingly common urinary diversion following cystectomy for bladder cancer. This is in recognition of the potential benefits of neobladder surgery over creation of an ileal conduit related to quality of life (QoL, such as avoiding the need to form a stoma with its cosmetic, psychological and other potential complications. The PubMed database was searched using relevant search terms for articles published electronically between January 1994 and April 2014. Full-text articles in English or with English translation were assessed for relevance to the topic before being included in the review. Patients with neobladders have comparable or better post-operative sexual function than those with ileal conduits. They also have comparable QoL to those with ileal conduits. Orthotopic neobladder is a good alternative to ileal conduit in suitable patients who do not want a stoma and are motivated to comply with neobladder training. However, the selection of a neobladder as the urinary diversion of choice requires that patients have good renal and liver functions and are likely to be compliant with neobladder training. With benefits also come potential risks of neobladder formation. These include electrolyte abnormalities and nocturnal incontinence. This short review highlights current aspects of neobladder formation and its potential advantages.

  7. Reconstruction tomography from incomplete projections

    International Nuclear Information System (INIS)

    In some instances, reconstruction radionuclide tomography must be carried out from projections that do not include projection values for all portions of the object to be reconstructed. This may occur, for example, when the field of view of the detector is limited, or when an opaque foreign body is present within the object. The effects of such incomplete projections upon reconstructions of computer-simulated phantoms were studied, using iterative and convolution methods. Several methods for reducing the resulting artifacts and inaccuracies are discussed

  8. Reconstruction of Double-Exposed Terahertz Hologram of Non-isolated Object

    Science.gov (United States)

    Hu, Jiaqi; Li, Qi; Chen, Guanghao

    2016-04-01

    When the non-isolated imaging objects are complex or critical imaging precision is required, single-exposure digital hologram technique may be insufficient. So in this paper, double-exposure method is adopted in 2.52-THz inline digital holography simulations and experiments. Experimental results indicate that, compared with the results reconstructed by single-exposure amplitude-constrained phase retrieval algorithm (S-APRA), double-exposure phase-constrained phase retrieval algorithm (D-PPRA) increases the contrast of the reconstruction image by 0.146 and double-exposure amplitude-constrained phase retrieval algorithm (D-APRA) increases the contrast by 0.225. In addition, when applied to non-isolated object reconstruction, phase retrieval algorithms with only amplitude constraint on the object plane work better than those with both amplitude and phase constraints.

  9. Reconstructions with identical filling (RIF) of the heart: a physiological approach to image reconstruction in coronary CT angiography

    Energy Technology Data Exchange (ETDEWEB)

    Reinartz, S.D.; Diefenbach, B.S.; Kuhl, C.K.; Mahnken, A.H. [University Hospital, RWTH Aachen University, Department of Diagnostic and Interventional Radiology, Aachen (Germany); Allmendinger, T. [Siemens Healthcare Sector, Department of Computed Tomography, Forchheim (Germany)

    2012-12-15

    To compare image quality in coronary artery computed tomography angiography (cCTA) using reconstructions with automated phase detection and Reconstructions computed with Identical Filling of the heart (RIF). Seventy-four patients underwent ECG-gated dual source CT (DSCT) between November 2009 and July 2010 for suspected coronary heart disease (n = 35), planning of transcatheter aortic valve replacement (n = 34) or evaluation of ventricular function (n = 5). Image data sets by the RIF formula and automated phase detection were computed and evaluated with the AHA 15-segment model and a 5-grade Likert scale (1: poor, 5: excellent quality). Subgroups regarding rhythm (sinus rhythm = SR; arrhythmia = ARR) and potential premedication were evaluated by a per-segment, per-vessel and per-patient analysis. RIF significantly improved image quality in 10 of 15 coronary segments (P < 0.05). More diagnostic segments were provided by RIF regarding the entire cohort (n = 693 vs. 590, P < 0.001) and all of the subgroups (e.g. ARR: n = 143 vs. 72, P < 0.001). In arrhythmic patients (n = 19), more diagnostic vessels (e.g. LAD: n = 10 vs. 3; P < 0.014) and complete data sets (n = 7 vs. 1; P < 0.001) were produced. RIF reconstruction is superior to automatic diastolic non-edited reconstructions, especially in arrhythmic patients. RIF theory provides a physiological approach for determining the optimal image reconstruction point in ECG-gated CT angiography. (orig.)

  10. Reconstructions with identical filling (RIF) of the heart: a physiological approach to image reconstruction in coronary CT angiography

    International Nuclear Information System (INIS)

    To compare image quality in coronary artery computed tomography angiography (cCTA) using reconstructions with automated phase detection and Reconstructions computed with Identical Filling of the heart (RIF). Seventy-four patients underwent ECG-gated dual source CT (DSCT) between November 2009 and July 2010 for suspected coronary heart disease (n = 35), planning of transcatheter aortic valve replacement (n = 34) or evaluation of ventricular function (n = 5). Image data sets by the RIF formula and automated phase detection were computed and evaluated with the AHA 15-segment model and a 5-grade Likert scale (1: poor, 5: excellent quality). Subgroups regarding rhythm (sinus rhythm = SR; arrhythmia = ARR) and potential premedication were evaluated by a per-segment, per-vessel and per-patient analysis. RIF significantly improved image quality in 10 of 15 coronary segments (P < 0.05). More diagnostic segments were provided by RIF regarding the entire cohort (n = 693 vs. 590, P < 0.001) and all of the subgroups (e.g. ARR: n = 143 vs. 72, P < 0.001). In arrhythmic patients (n = 19), more diagnostic vessels (e.g. LAD: n = 10 vs. 3; P < 0.014) and complete data sets (n = 7 vs. 1; P < 0.001) were produced. RIF reconstruction is superior to automatic diastolic non-edited reconstructions, especially in arrhythmic patients. RIF theory provides a physiological approach for determining the optimal image reconstruction point in ECG-gated CT angiography. (orig.)

  11. Determining Reconstruction Variables and Parameters on Improved Multi-Objective Immune Algorithm

    Directory of Open Access Journals (Sweden)

    Wei Wang

    2013-12-01

    Full Text Available Aimed at multi-dimension of evaluating reconstruction effect and the correlation between reconstruction variables and reconstruction parameters, improved multi-objective immune algorithm (IMOIA was proposed to simultaneously determine reconstruction variables and parameters in multivariate time series phase space. In IMOIA, antibody coding was binary strings cascade of multi-parameter, antibody evaluating was three functions, and a new population evaluating S- is presented. Immune operators were designed: overall clone operator to improve speed, mutation operator with multiple changing probability on gene loci and S enhanced local and global search capability to ensure algorithm convergence, Clonal Selection operator on Rank and Crowding-distance to ensure solutions uniformity, repetitive antibodies determination and deletion operator to ensure solutions diversity. Use our method to two benchmarking chaos system, simulation results showed that our method can simultaneously solved multiple combinations of optimal reconstruction variables and parameters and had obvious superiority to other intelligent optimization algorithms and determining reconstruction parameter methods.

  12. Which one Enhances Muscular Performance in ACL Reconstructed Subjects

    OpenAIRE

    Harput, Gulcan; Ulusoy, Burak; Atay, Ahmet Ozgur; Baltacı, Gul

    2014-01-01

    Objectives: The aim of this study was to investigate the effects of functional knee brace and kinesiotaping on muscular performance in anterior cruciate ligament reconstructed subjects who reached return to sport phase of the rehabilitation. Methods: Twenty (17 males, 3 females, Age: 24.7±7.1 years, Body weight: 74.4±12.0 kg, Height: 177.9±6.5 cm, BMI: 23.9±3.6 kg/m2) subjects who underwent anterior cruciate ligament reconstruction by using hamstring tendon auto graft were included in this st...

  13. Phase space density measurement of interfering X-rays

    International Nuclear Information System (INIS)

    We report a reconstruction of the phase space distribution of an X-ray beam after it has passed through a set of Young's slits. The resulting interference pattern has a quasi-probability distribution that has negative regions that do not have a classical interpretation. We experimentally reconstruct and observe these negative parts of the phase space distribution

  14. Bioluminescence tomography based on the phase approximation model

    OpenAIRE

    Cong, W.; Wang, G

    2010-01-01

    A reconstruction method of bioluminescence sources is proposed based on a phase approximation model. Compared with the diffuse approximation, this phase approximation model more correctly predicts bioluminescence photon propagation in biological tissues, so that bioluminescence tomography can accurately locate and quantify the distribution of bioluminescence sources. The compressive sensing (CS) technique is applied to regularize the inverse source reconstruction to enhance numerical stabilit...

  15. Quantum Enhanced Phase Retrieval

    CERN Document Server

    Liberman, Liat; Poem, Eilon; Silberberg, Yaron

    2015-01-01

    The retrieval of phases from intensity measurements is a key process in many fields in science, from optical microscopy to x-ray crystallography. Here we study phase retrieval of a one-dimensional multi-phase object that is illuminated by quantum states of light. We generalize the iterative Gerchberg-Saxton algorithm to photon correlation measurements on the output plane, rather than the standard intensity measurements. We report a numerical comparison of classical and quantum phase retrieval of a small one-dimensional object of discrete phases from its far-field diffraction. While the classical algorithm was ambiguous and often converged to wrong solutions, quantum light produced a unique reconstruction with smaller errors and faster convergence. We attribute these improvements to a larger Hilbert space that constrains the algorithm.

  16. Reconstruction of defects by ultrasonic testing using synthetic aperture procedures

    International Nuclear Information System (INIS)

    The three methods ALOK (Amplitude Time Locus Curves), PHASED ARRAY and LSAFT (Line-Synthetic-Aperture-Focusing-Technique) use the method of synthesizing a large aperture by moving a probe. All methods are based on the time-of-flight or phase information and less to amplitude information. They differ in the state of development, in the complexity of data acquisition and reconstruction. The ALOK method is closest to those ultrasonic inspection methods used today in inservice inspection of nuclear pressure vessels. PHASED ARRAY combined with the compound scan synthesizes the divergent beam too and insonifies a reflector from many different insonification directions with high energy. LSAFT, like the others, reconstructs a B-scan image. For all three methods examples have been shown which demonstrate the state of development of these systems

  17. The recording of digital hologram at short distance and reconstruction using convolution approach

    Institute of Scientific and Technical Information of China (English)

    Chen Li-Ping; LU Xiao-Xu

    2009-01-01

    By adopting in-line lensless Fourier setup and phase-shifting technique, we recorded the phase-shifting digital hologram at short distance. As the Fresnel diffraction condition is no longer valid, the convolution approach is chosen for the reconstruction. However, the simulated reference wave for the reconstruction would suffer from severe under-sampling due to the comparatively large pixel size. To solve this problem, sine-interpolation is introduced to get the pixel-size of the hologram reduced prior to the reconstruction. The experimental results show that an object image of high fidelity is obtained with this method.

  18. Reconstruction techniques for optoacoustic imaging

    Science.gov (United States)

    Frenz, Martin; Koestli, Kornel P.; Paltauf, Guenther; Schmidt-Kloiber, Heinz; Weber, Heinz P.

    2001-06-01

    Optoacoustics is a method to gain information from inside a tissue. This is done by irradiating a tissue with a short light pulse, which generates a pressure distribution inside the tissue that mirrors the absorber distribution. The pressure distribution measured on the tissue-surface allows, by applying a back-projection method, to calculate a tomography image of the absorber distribution. This study presents a novel computational algorithm based on Fourier transform, which, at least in principle, yields an exact 3D reconstruction of the distribution of absorbed energy density inside turbid media. The reconstruction is based on 2D pressure distributions captured outside at different times. The FFT reconstruction algorithm is first tested in the back projection of simulated pressure transients of small model absorbers, and finally applied to reconstruct the distribution of artificial blood vessels in three dimensions.

  19. Breast Reconstruction with Tissue Expansion

    Medline Plus

    Full Text Available ... to go with Tamoxifen. At that point in time she did not want to get a reconstruction, ... her work and she's more comfortable with her time, she said she wanted to pursue the breast ...

  20. Breast Reconstruction with Tissue Expansion

    Medline Plus

    Full Text Available ... come to my practice a few months ago seeking a left breast reconstruction after mastectomy. She had ... Veritas Collagen Matrix sling in order to help support the expansion because there is possible radiation damage ...

  1. Submicron STIM tomography reconstruction techniques

    International Nuclear Information System (INIS)

    One-dimensional projections of ion energy loss have been converted to areal density using tabulated stopping powers in a scanning transmission ion microscopy (STIM) reconstruction of a test object, displaying a spatial resolution of 0.37 μm. Location and registration of the centre of areal mass density in each projection provides a means of overcoming (a) the misalignment of the specimen rotation axis with the centre of the scan path and (b) deviations of the specimen from its precession around the axis of rotation. Multiplicative algebraic reconstruction technique (ART), filtered backprojection and maximum-entropy algorithms for the reconstruction of the object are considered. Maximum entropy is shown to produce an image with the least number of artifacts. However, when time considerations are taken into account, it is found that filtered backprojection is the preferred algorithm for a tomographic reconstruction. (orig.)

  2. Reconstruction within the Zeldovich approximation

    CERN Document Server

    White, Martin

    2015-01-01

    The Zeldovich approximation, 1st order Lagrangian perturbation theory, provides a good description of the clustering of matter and galaxies on large scales. The acoustic feature in the large-scale correlation function of galaxies imprinted by sound waves in the early Universe has been successfully used as a `standard ruler' to constrain the expansion history of the Universe. The standard ruler can be improved if a process known as density field reconstruction is employed. In this paper we develop the Zeldovich formalism to compute the correlation function of biased tracers in both real- and redshift-space using the simplest reconstruction algorithm with a Gaussian kernel and compare to N-body simulations. The model qualitatively describes the effects of reconstruction on the simulations, though its quantitative success depends upon how redshift-space distortions are handled in the reconstruction algorithm.

  3. Vermilion Reconstruction with Genital Mucosa.

    Science.gov (United States)

    Müller-Richter, Urs D A; Weyandt, Gerhard H; Woeckel, Achim; Kübler, Alexander C

    2016-05-01

    Functional and aesthetical reconstruction, especially of the upper lip after ablative tumor surgery, can be very challenging. The skin of the lip might be sufficiently reconstructed by transpositional flaps from the nasolabial or facial area. Large defects of the lip mucosa, including the vestibule, are even more challenging due to the fact that flaps from the inner lining of the oral cavity often lead to functional impairments. We present a case of multiple vermilion and skin resections of the upper lip. At the last step, we had to resect even the whole vermilion mucosa, including parts of the oral mucosa of the vestibule, leaving a bare orbicularis oris muscle. To reconstruct the mucosal layer, we used a mucosal graft from the labia minora and placed it on the compromised lip and the former transpositional flaps for the reconstructed skin of the upper lip with very good functional and aesthetic results. PMID:27579226

  4. Quantitative phase imaging of Breast cancer cell based on SLIM

    Science.gov (United States)

    Wu, Huaqin; Li, Zhifang; Li, Hui; Wu, Shulian

    2016-02-01

    We illustrated a novel optical microscopy technique to observe cell dynamics via spatial light interference microscopy (SLIM). SLIM combines Zemike's phase contrast microscopy and Gabor's holography. When the light passes through the transparent specimens, it could render high contrast intensity and record the phase information from the object. We reconstructed the Breast cancer cell phase image by SLIM and the reconstruction algorithm. Our investigation showed that SLIM has the ability to achieve the quantitative phase imaging (QPI).

  5. Online track reconstruction at hadron colliders

    International Nuclear Information System (INIS)

    Real time event reconstruction plays a fundamental role in High Energy Physics experiments. Reducing the rate of data to be saved on tape from millions to hundreds per second is critical. In order to increase the purity of the collected samples, rate reduction has to be coupled with the capability to simultaneously perform a first selection of the most interesting events. A fast and efficient online track reconstruction is important to effectively trigger on leptons and/or displaced tracks from b-quark decays. This talk will be an overview of online tracking techniques in different HEP environments: we will show how H1 experiment at HERA faced the challenges of online track reconstruction implementing pattern matching and track linking algorithms on CAMs and FPGAs in the Fast Track Processor (FTT). The pattern recognition technique is also at the basis of the Silicon Vertex Trigger (SVT) at the CDF experiment at Tevatron: coupled to a very fast fitting phase, SVT allows to trigger on displaced tracks, thus greatly increasing the efficiency for the hadronic B decay modes. A recent upgrade of the SVT track fitter, the Giga-fitter, can perform more than 1 fit/ns and further improves the CDF online trigger capabilities at high luminosity. At SLHC, where luminosities will be 2 orders of magnitude greater than Tevatron, online tracking will be much more challenging: we will describe CMS future plans for a Level-1 track trigger and the Fast Tracker (FTK) processor at the ATLAS experiment, based on the Giga-fitter architecture and designed to provide high quality tracks reconstructed over the entire detector in time for a Level-2 trigger decision.luminosity. At SLHC, where luminosities will be 2 orders of magnitude greater than Tevatron, online tracking will be much more challenging: we will describe CMS future plans for a Level-1 track trigger and the Fast Tracker (FTK) processor at the Atlas experiment, based on the Giga-fitter architecture and designed to provide high

  6. Provincial reconstruction teams improving effectiveness

    OpenAIRE

    Sellers, Cameron S.

    2007-01-01

    Provincial Reconstruction Teams (PRTs) are currently prominent constructs for stabilization and reconstruction in Afghanistan and Iraq. PRTs are composed of civil-military teams, including elements from coalition partners and the host-nation, and involve multiple military services and civilian agencies. Their missions are to extend the legitimacy of the central government throughout the country and to use Civil Military Operations (CMO) to counter anti-government forces. PRTs are prominent,...

  7. Current Concepts in ACL Reconstruction

    OpenAIRE

    Fu, Freddie H; Cohen, Steven B.

    2008-01-01

    Current Concepts in ACL Reconstruction is a complete reference text composed of the most thorough collection of topics on the ACL and its surgical reconstruction compiled, with contributions from some of the world's experts and most experienced ACL surgeons. Various procedures mentioned throughout the text are also demonstrated in an accompanying video CD-ROM. PURPOSE Composing a single, comprehensive and complete information source on ACL including basic sciences, clinical issues, latest con...

  8. Equilibrium Reconstruction in EAST Tokamak

    Institute of Scientific and Technical Information of China (English)

    QIAN Jinping; WAN Baonian; L. L. LAO; SHEN Biao; S. A. SABBAGH; SUN Youwen; LIU Dongmei; XIAO Singjia; REN Qilong; GONG Xianzu; LI Jiangang

    2009-01-01

    Reconstruction of experimental axisymmetric equilibria is an important part of toka-mak data analysis. Fourier expansion is applied to reconstruct the vessel current distribution in EFIT code. Benchmarking and testing calculations are performed to evaluate and validate this algorithm. Two cases for circular and non-circular plasma discharges are presented. Fourier ex-pansion used to fit the eddy current is a robust method and the real time EFIT can be introduced to the plasma control system in the coming campaign.

  9. Reconstructing pedigrees: a stochastic perspective

    OpenAIRE

    Thatte, Bhalchandra D.; Steel, Mike

    2007-01-01

    A pedigree is a directed graph that describes how individuals are related through ancestry in a sexually-reproducing population. In this paper we explore the question of whether one can reconstruct a pedigree by just observing sequence data for present day individuals. This is motivated by the increasing availability of genomic sequences, but in this paper we take a more theoretical approach and consider what models of sequence evolution might allow pedigree reconstruction (given sufficiently...

  10. Technical basis for dose reconstruction

    International Nuclear Information System (INIS)

    The purpose of this paper is to consider two general topics: technical considerations of why dose-reconstruction studies should or should not be performed and methods of dose reconstruction. The first topic is of general and growing interest as the number of dose-reconstruction studies increases, and one asks the question whether it is necessary to perform a dose reconstruction for virtually every site at which, for example, the Department of Energy (DOE) has operated a nuclear-related facility. And there is the broader question of how one might logically draw the line at performing or not performing dose-reconstruction (radiological and chemical) studies for virtually every industrial complex in the entire country. The second question is also of general interest. There is no single correct way to perform a dose-reconstruction study, and it is important not to follow blindly a single method to the point that cheaper, faster, more accurate, and more transparent methods might not be developed and applied

  11. Lip Reconstruction after Tumor Ablation

    Science.gov (United States)

    Ebrahimi, Ali; Kalantar Motamedi, Mohammad Hossein; Ebrahimi, Azin; Kazemi, Mohammad; Shams, Amin; Hashemzadeh, Haleh

    2016-01-01

    Approximately 25% of all oral cavity carcinomas involve the lips, and the primary management of these lesions is complete surgical resection. Loss of tissue in the lips after resection is treated with a variety of techniques, depending on the extension and location of the defect. Here we review highly accepted techniques of lip reconstruction and some of new trials with significant clinical results. Reconstruction choice is primarily depend to size of the defect, localization of defect, elasticity of tissues. But patient’s age, comorbidities, and motivation are also important. According to the defect location and size, different reconstruction methods can be used. For defects involved less than 30% of lips, primary closures are sufficient. In defects with 35–70% lip involvement, the Karapandzic, Abbe, Estlander, McGregor or Gillies’ fan flaps or their modifications can be used. When lip remaining tissues are insufficient, cheek tissue can be used in Webster and Bernard advancement flaps and their various modifications. Deltopectoral or radial forearm free flaps can be options for large defects of the lip extending to the Jaws. To achieve best functional and esthetic results, surgeons should be able to choose most appropriate reconstruction method. Considering defects’ size and location, patients’ expects and surgeon’s ability and knowledge, a variety of flaps are presented in order to reconstruct defects resulted from tumor ablation. It’s necessary for surgeons to trace the recent innovations in lip reconstruction to offer best choices to patients. PMID:27308236

  12. Iterative 4D cardiac micro-CT image reconstruction using an adaptive spatio-temporal sparsity prior

    Science.gov (United States)

    Ritschl, Ludwig; Sawall, Stefan; Knaup, Michael; Hess, Andreas; Kachelrieß, Marc

    2012-03-01

    Temporal-correlated image reconstruction, also known as 4D CT image reconstruction, is a big challenge in computed tomography. The reasons for incorporating the temporal domain into the reconstruction are motions of the scanned object, which would otherwise lead to motion artifacts. The standard method for 4D CT image reconstruction is extracting single motion phases and reconstructing them separately. These reconstructions can suffer from undersampling artifacts due to the low number of used projections in each phase. There are different iterative methods which try to incorporate some a priori knowledge to compensate for these artifacts. In this paper we want to follow this strategy. The cost function we use is a higher dimensional cost function which accounts for the sparseness of the measured signal in the spatial and temporal directions. This leads to the definition of a higher dimensional total variation. The method is validated using in vivo cardiac micro-CT mouse data. Additionally, we compare the results to phase-correlated reconstructions using the FDK algorithm and a total variation constrained reconstruction, where the total variation term is only defined in the spatial domain. The reconstructed datasets show strong improvements in terms of artifact reduction and low-contrast resolution compared to other methods. Thereby the temporal resolution of the reconstructed signal is not affected.

  13. Oak Ridge Health Studies Phase 1 report, Volume 2: Part A, Dose Reconstruction Feasibility Study. Tasks 1 and 2, A summary of historical activities on the Oak Ridge Reservation with emphasis on information concerning off-site emissions of hazardous materials

    Energy Technology Data Exchange (ETDEWEB)

    Bruce, G.M.; Buddenbaum, J.E.; Lamb, J.K.; Widner, T.E.

    1993-09-01

    The Phase I feasibility study has focused on determining the availability of information for estimating exposures of the public to chemicals and radionuclides released as a result of historical operation of the facilities at the Oak Ridge Reservation (ORR). The estimation of such past exposures is frequently called dose reconstruction. The initial project tasks, Tasks 1 and 2 were designed to identify and collect information that documents the history of activities at the ORR that resulted in the release of contamination and to characterize the availability of data that could be used to estimate the magnitude of the contaminant releases or public exposures. A history of operations that are likely to have generated off-site releases has been documented as a result of Task 1 activities. The activities required to perform this task involved the extensive review of historical operation records and interviews with present and past employees as well as other knowledgeable individuals. The investigation process is documented in this report. The Task 1 investigations have led to the documentation of an overview of the activities that have taken place at each of the major complexes, including routine operations, waste management practices, special projects, and accidents and incidents. Historical activities that appear to warrant the highest priority in any further investigations were identified based on their likely association with off-site emissions of hazardous materials as indicated by the documentation reviewed or information obtained in interviews.

  14. On $\\mathfrak{I}$-reconstruction Property

    OpenAIRE

    Vashisht, L. K.; Khattar, Geetika

    2013-01-01

    Reconstruction property in Banach spaces introduced and studied by Casazza and Christensen in [1]. In this paper we introduce reconstruction property in Banach spaces which satisfy $\\mathfrak{I}$-property. A characterization of reconstruction property in Banach spaces which satisfy $\\mathfrak{I}$-property in terms of frames in Banach spaces is obtained. Banach frames associated with reconstruction property are discussed.

  15. Ulnar Collateral Ligament Reconstruction

    Science.gov (United States)

    Erickson, Brandon J.; Bach, Bernard R.; Cohen, Mark S.; Bush-Joseph, Charles A.; Cole, Brian J.; Verma, Nikhil N.; Nicholson, Gregory P.; Romeo, Anthony A.

    2016-01-01

    Background: Ulnar collateral ligament reconstruction (UCLR) is a common surgery performed in professional, collegiate, and high school athletes. Purpose: To report patient demographics, surgical techniques, and outcomes of all UCLRs performed at a single institution from 2004 to 2014. Study Design: Case series; Level of evidence, 4. Methods: All patients who underwent UCLR from January 1, 2004, through December 31, 2014, at a single institution were identified. Charts were reviewed to determine patient age, sex, date of surgery, sport played, athletic level, surgical technique, graft type, and complications. Data were collected prospectively, and patients were contacted via phone calls to obtain the return-to-sport rate, Conway-Jobe score, Andrews-Timmerman score, and Kerlan-Jobe Orthopaedic Clinic (KJOC) Shoulder and Elbow score. Continuous variable data were reported as weighted means, and categorical variable data were reported as frequencies with percentages. Results: A total of 187 patients (188 elbows) underwent UCLR during the study period (92% male; mean age, 19.6 ± 4.7 years; 78.2% right elbows). There were 165 baseball players (87.8% of all patients), 155 of whom were pitchers (82.5% of all patients). Ninety-seven (51.6%) were college athletes, 68 (36.2%) high school athletes, and 7 (3.7%) professional athletes at the time of surgery. The docking technique was used in 110 (58.5%) patients while the double-docking technique was used in 78 (41.5%). An ipsilateral palmaris longus graft was used in 110 (58.5%) patients while a hamstring autograft was used in 48 (25.5%) patients. The ulnar nerve was subcutaneously transposed in 79 (42%) patients. Clinical follow-up data were available on 85 patients. Mean follow-up was 60 ± 30.8 months. Overall, 94.1% of patients were able to return to sport and had a Conway-Jobe score of good/excellent while 4.3% had a score of fair. The mean KJOC score was 90.4 ± 6.7 and mean Andrews-Timmerman score was 92.5 ± 7

  16. Muon reconstruction performance in ATLAS at Run 2

    CERN Document Server

    Lesage, Arthur; The ATLAS collaboration

    2016-01-01

    This article documents the performance of the ATLAS muon identification and reconstruction using the first LHC dataset recorded at $\\sqrt{s} = 13$ TeV in 2015. Using a large sample of $J/\\psi\\rightarrow\\mu\\mu$ and $Z\\rightarrow\\mu\\mu$ decays, measurements of the reconstruction efficiency, as well as of the momentum scale and resolution, are presented and compared to Monte Carlo simulations. The reconstruction efficiency is measured to be close to $99\\%$ over most of the covered phase space ($|\\eta| 2.2$, the $p_{\\text{T}}$ resolution for a typical muon from $Z\\rightarrow\\mu\\mu$ decays is $2.9\\%$ while the precision on the momentum scale for low-$p_{\\text{T}}$ muons from $J/\\psi\\rightarrow\\mu\\mu$ decays is about $0.2\\%$.

  17. Use of digital wave front reconstruction for vibration analysis

    Science.gov (United States)

    Picart, Pascal; Leval, Julien; Boileau, Jean-Pierre; Pascal, Jean-Claude; Dalmont, Jean-Pierre

    2006-09-01

    This paper aims to present the different opportunities using digital wave front reconstruction in vibration analysis. The paper deals with off axis digital holography for which the wave front reconstruction is performed by fast Fourier transform methods. According to this way for the object plane reconstruction, we discuss about image formation by considering the exposure time of the detector. For the case of a long exposure time compared to the vibration period, that is the time-averaging regime, applications are presented, examples of which include vibrations of a clarinet reed and detection of defaults in a dome mode. For the case of a short exposure time compared to the vibration period, algorithm for the full field bidimensional amplitude and phase retrieving is presented. Applications of the method are presented, example of which include modal characterization of loudspeakers and bidimensional vibrometry of elastomer components.

  18. PAINTER: a spatio-spectral image reconstruction algorithm for optical interferometry

    CERN Document Server

    Schutz, Antony; Mary, David; Soulez, Férréol; Thiébaut, Éric; Vannier, Martin

    2014-01-01

    Astronomical optical interferometers sample the Fourier transform of the intensity distribution of a source at the observation wavelength. Because of rapid perturbations caused by atmospheric turbulence, the phases of the complex Fourier samples (visibilities) cannot be directly exploited. Consequently, specific image reconstruction methods have been devised in the last few decades. Modern polychromatic optical interferometric instruments are now paving the way to multiwavelength imaging. This paper is devoted to the derivation of a spatio-spectral (3D) image reconstruction algorithm, coined PAINTER (Polychromatic opticAl INTErferometric Reconstruction software). The algorithm relies on an iterative process, which alternates estimation of polychromatic images and of complex visibilities. The complex visibilities are not only estimated from squared moduli and closure phases, but also differential phases, which helps to better constrain the polychromatic reconstruction. Simulations on synthetic data illustrate ...

  19. A novel random phase-shifting digital holographic microscopy method

    Institute of Scientific and Technical Information of China (English)

    XIE HuiMin; HU ZhenXing; DAI FuLong; LI YanJie; CHEN PengWan; ZHANG QingMing; HUANG FengLei

    2009-01-01

    This paper proposes s new method that reconstructs the information of specimen by using random phase shift step in digital holographic microscopy (DHM). The principles of the method are described and discussed in detail. In practical experiment, because the phase shifter is neither perfectly linear nor calibrated, digital holograms with inaccurate phase shift step are recorded by the charge-coupled device (CCD). The phase could be accurately reconstructed from the recorded digital holograms by using the random phase-shifting algorithm, which makes up for reconstructed phase error caused by ordinary phase-shifting algorithm. The phase aberration compensation is also discussed. In order to verify the flexibility of the proposed method, numerical simulation of random phase-shifting DHM was carried out. The simulation results illustrated that the presented method is effective when the phase shift step is unknown or random in DHM.

  20. A novel random phase-shifting digital holographic microscopy method

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    This paper proposes a new method that reconstructs the information of specimen by using random phase shift step in digital holographic microscopy (DHM). The principles of the method are described and discussed in detail. In practical experiment, because the phase shifter is neither perfectly linear nor calibrated, digital holograms with inaccurate phase shift step are recorded by the charge-coupled device (CCD). The phase could be accurately reconstructed from the recorded digital holograms by using the random phase-shifting algorithm, which makes up for reconstructed phase error caused by ordinary phase-shifting algorithm. The phase aberration compensation is also discussed. In order to verify the flexibility of the proposed method, numerical simulation of random phase-shifting DHM was carried out. The simulation results illustrated that the presented method is effective when the phase shift step is unknown or random in DHM.

  1. Bubble reconstruction method for wire-mesh sensors measurements

    Science.gov (United States)

    Mukin, Roman V.

    2016-08-01

    A new algorithm is presented for post-processing of void fraction measurements with wire-mesh sensors, particularly for identifying and reconstructing bubble surfaces in a two-phase flow. This method is a combination of the bubble recognition algorithm presented in Prasser (Nuclear Eng Des 237(15):1608, 2007) and Poisson surface reconstruction algorithm developed in Kazhdan et al. (Poisson surface reconstruction. In: Proceedings of the fourth eurographics symposium on geometry processing 7, 2006). To verify the proposed technique, a comparison was done of the reconstructed individual bubble shapes with those obtained numerically in Sato and Ničeno (Int J Numer Methods Fluids 70(4):441, 2012). Using the difference between reconstructed and referenced bubble shapes, the accuracy of the proposed algorithm was estimated. At the next step, the algorithm was applied to void fraction measurements performed in Ylönen (High-resolution flow structure measurements in a rod bundle (Diss., Eidgenössische Technische Hochschule ETH Zürich, Nr. 20961, 2013) by means of wire-mesh sensors in a rod bundle geometry. The reconstructed bubble shape yields bubble surface area and volume, hence its Sauter diameter d_{32} as well. Sauter diameter is proved to be more suitable for bubbles size characterization compared to volumetric diameter d_{30}, proved capable to capture the bi-disperse bubble size distribution in the flow. The effect of a spacer grid was studied as well: For the given spacer grid and considered flow rates, bubble size frequency distribution is obtained almost at the same position for all cases, approximately at d_{32} = 3.5 mm. This finding can be related to the specific geometry of the spacer grid or the air injection device applied in the experiments, or even to more fundamental properties of the bubble breakup and coagulation processes. In addition, an application of the new algorithm for reconstruction of a large air-water interface in a tube bundle is

  2. Quantum interferences reconstruction with low homodyne detection efficiency

    Energy Technology Data Exchange (ETDEWEB)

    Esposito, Martina; Randi, Francesco [Universita degli studi di Trieste, Dipartimento di Fisica, Trieste (Italy); Titimbo, Kelvin; Zimmermann, Klaus; Benatti, Fabio [Universita degli studi di Trieste, Dipartimento di Fisica, Trieste (Italy); Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, Trieste (Italy); Kourousias, Georgios; Curri, Alessio [Sincrotrone Trieste S.C.p.A., Trieste (Italy); Floreanini, Roberto [Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, Trieste (Italy); Parmigiani, Fulvio [Universita degli studi di Trieste, Dipartimento di Fisica, Trieste (Italy); Sincrotrone Trieste S.C.p.A., Trieste (Italy); University of Cologne, Institute of Physics II, Cologne (Germany); Fausti, Daniele [Universita degli studi di Trieste, Dipartimento di Fisica, Trieste (Italy); Sincrotrone Trieste S.C.p.A., Trieste (Italy)

    2016-12-15

    Optical homodyne tomography consists in reconstructing the quantum state of an optical field from repeated measurements of its amplitude at different field phases (homodyne data). The experimental noise, which unavoidably affects the homodyne data, leads to a detection efficiency η<1. The problem of reconstructing quantum states from noisy homodyne data sets prompted an intense scientific debate about the presence or absence of a lower homodyne efficiency bound (η>0.5) below which quantum features, like quantum interferences, cannot be retrieved. Here, by numerical experiments, we demonstrate that quantum interferences can be effectively reconstructed also for low homodyne detection efficiency. In particular, we address the challenging case of a Schroedinger cat state and test the minimax and adaptive Wigner function reconstruction technique by processing homodyne data distributed according to the chosen state but with an efficiency η>0.5. By numerically reproducing the Schroedinger's cat interference pattern, we give evidence that quantum state reconstruction is actually possible in these conditions, and provide a guideline for handling optical tomography based on homodyne data collected by low efficiency detectors. (orig.)

  3. High numerical aperture holographic microscopy reconstruction with extended z range

    CERN Document Server

    Verrier, Nicolas; Tessier, Gilles; Gross, Michel

    2015-01-01

    An holographic microscopy reconstruction method compatible with high numerical aperture microscope objective (MO) up to NA=1.4 is proposed. After off axis and reference field curvature corrections, and after selection of the +1 grating order holographic image, a phase mask that transforms the optical elements of the holographic setup into an afocal device is applied in the camera plane. The reconstruction is then made by the angular spectrum method. The field is first propagated in the image half space from the camera to the afocal image of the MO optimal plane (plane for which MO has been designed) by using a quadratic kernel. The field is then propagated from the MO optimal plane to the object with the exact kernel. Calibration of the reconstruction is made by imaging a calibrated object like an USAF resolution target for different positions along $z$. Once the calibration is done, the reconstruction can be made with an object located in any plane $z$. The reconstruction method has been validated experiment...

  4. High numerical aperture holographic microscopy reconstruction with extended z range.

    Science.gov (United States)

    Verrier, N; Donnarumma, D; Tessier, G; Gross, M

    2015-11-10

    A holographic microscopy reconstruction method compatible with a high numerical aperture microscope objective (MO) up to NA=1.4 is proposed. After off-axis and reference field curvature corrections, and after selection of the +1 grating order holographic image, a phase mask that transforms the optical elements of the holographic setup into an afocal device is applied in the camera plane. The reconstruction is then made by the angular spectrum method. The field is first propagated in the image half-space from the camera to the afocal image of the MO optimal plane (the plane for which the MO has been designed) by using a quadratic kernel. The field is then propagated from the MO optimal plane to the object with the exact kernel. Calibration of the reconstruction is made by imaging a calibrated object such as a USAF resolution target for different positions along z. Once the calibration is done, the reconstruction can be made with an object located in any plane z. The reconstruction method has been validated experimentally with a USAF target imaged with a NA=1.4 microscope objective. Near-optimal resolution is obtained over an extended range (±50  μm) of z locations. PMID:26560784

  5. Quantum interferences reconstruction with low homodyne detection efficiency

    International Nuclear Information System (INIS)

    Optical homodyne tomography consists in reconstructing the quantum state of an optical field from repeated measurements of its amplitude at different field phases (homodyne data). The experimental noise, which unavoidably affects the homodyne data, leads to a detection efficiency η<1. The problem of reconstructing quantum states from noisy homodyne data sets prompted an intense scientific debate about the presence or absence of a lower homodyne efficiency bound (η>0.5) below which quantum features, like quantum interferences, cannot be retrieved. Here, by numerical experiments, we demonstrate that quantum interferences can be effectively reconstructed also for low homodyne detection efficiency. In particular, we address the challenging case of a Schroedinger cat state and test the minimax and adaptive Wigner function reconstruction technique by processing homodyne data distributed according to the chosen state but with an efficiency η>0.5. By numerically reproducing the Schroedinger's cat interference pattern, we give evidence that quantum state reconstruction is actually possible in these conditions, and provide a guideline for handling optical tomography based on homodyne data collected by low efficiency detectors. (orig.)

  6. Hybrid x-space: a new approach for MPI reconstruction

    Science.gov (United States)

    Tateo, A.; Iurino, A.; Settanni, G.; Andrisani, A.; Stifanelli, P. F.; Larizza, P.; Mazzia, F.; Mininni, R. M.; Tangaro, S.; Bellotti, R.

    2016-06-01

    Magnetic particle imaging (MPI) is a new medical imaging technique capable of recovering the distribution of superparamagnetic particles from their measured induced signals. In literature there are two main MPI reconstruction techniques: measurement-based (MB) and x-space (XS). The MB method is expensive because it requires a long calibration procedure as well as a reconstruction phase that can be numerically costly. On the other side, the XS method is simpler than MB but the exact knowledge of the field free point (FFP) motion is essential for its implementation. Our simulation work focuses on the implementation of a new approach for MPI reconstruction: it is called hybrid x-space (HXS), representing a combination of the previous methods. Specifically, our approach is based on XS reconstruction because it requires the knowledge of the FFP position and velocity at each time instant. The difference with respect to the original XS formulation is how the FFP velocity is computed: we estimate it from the experimental measurements of the calibration scans, typical of the MB approach. Moreover, a compressive sensing technique is applied in order to reduce the calibration time, setting a fewer number of sampling positions. Simulations highlight that HXS and XS methods give similar results. Furthermore, an appropriate use of compressive sensing is crucial for obtaining a good balance between time reduction and reconstructed image quality. Our proposal is suitable for open geometry configurations of human size devices, where incidental factors could make the currents, the fields and the FFP trajectory irregular.

  7. Titanium template for scaphoid reconstruction.

    Science.gov (United States)

    Haefeli, M; Schaefer, D J; Schumacher, R; Müller-Gerbl, M; Honigmann, P

    2015-06-01

    Reconstruction of a non-united scaphoid with a humpback deformity involves resection of the non-union followed by bone grafting and fixation of the fragments. Intraoperative control of the reconstruction is difficult owing to the complex three-dimensional shape of the scaphoid and the other carpal bones overlying the scaphoid on lateral radiographs. We developed a titanium template that fits exactly to the surfaces of the proximal and distal scaphoid poles to define their position relative to each other after resection of the non-union. The templates were designed on three-dimensional computed tomography reconstructions and manufactured using selective laser melting technology. Ten conserved human wrists were used to simulate the reconstruction. The achieved precision measured as the deviation of the surface of the reconstructed scaphoid from its virtual counterpart was good in five cases (maximal difference 1.5 mm), moderate in one case (maximal difference 3 mm) and inadequate in four cases (difference more than 3 mm). The main problems were attributed to the template design and can be avoided by improved pre-operative planning, as shown in a clinical case. PMID:25167978

  8. InGaN(0001) surface reconstructions

    International Nuclear Information System (INIS)

    Surfaces of the InGaN alloy system are hardly understood in terms of their atomic structure. In order to reveal the principal mechanisms for the formation of surface reconstructions the preparation of such surfaces for measurements in ultra-high vacuum (UHV) is crucial. The preparation and surface structure of high quality group-III-polar (0001) InGaN layers grown by metal-organic vapor phase epitaxy have been investigated. We show that different InGaN surface reconstructions such as (1 x 1), (1+1/6), (2 x 2) and (√(3) x √(3))R30 circle can be obtained by annealing at various temperatures under ultra-high vacuum and nitrogen-rich conditions as observed by low energy electron diffraction. Depending on the annealing temperature and nitrogen supply these surfaces exhibit significant differences in stoichiometry and morphology as determined by Auger electron spectroscopy and atomic force microscopy measurements. We show that the (2 x 2) and (√(3) x √(3))R30 circle are explained by indium-adatoms and a related In depletion in the first group-III layer underneath whereas the (1+1/6) exhibits a discommensurate overlayer of group-III-atoms. Strain-relaxation is suggested to explain this structure formation.

  9. Domain formation on the reconstructed GaAs(001) surface

    Science.gov (United States)

    Behrend, J.; Wassermeier, M.; Däweritz, L.; Ploog, K. H.

    1995-11-01

    We have investigated the transition of the GaAs(001) surface from the As rich to the Ga rich phases in the reconstruction phase diagram by in-situ scanning tunneling microscopy (STM) and reflection high energy electron diffraction (RHEED). The initial surface prepared by molecular beam epitaxy (MBE) and monitored by RHEED shows a regular (2 × 4) As stabilized reconstruction. The different stages of the transition are achieved by post-growth annealing under ultrahigh vacuum conditions. STM images illustrate the flexibility of the GaAs(001) surface to adapt itself to changes on the growth conditions by forming various reconstructions and domain structures. Especially near the transition from the As to the Ga terminated surface, As rich (2 × 6) and Ga rich (4 × 2) domains exist at the same time. A domain structure formed in this way leads to the well known (4 × 6) RHEED pattern which is thus not an intrinsic reconstruction. At even higher annealing temperatures large scale STM images reveal characteristically shaped step bunches and multilayer high steps due to sublimation of GaAs.

  10. Spectrotemporal CT data acquisition and reconstruction at low dose

    Energy Technology Data Exchange (ETDEWEB)

    Clark, Darin P.; Badea, Cristian T., E-mail: cristian.badea@duke.edu [Department of Radiology, Center for In Vivo Microscopy, Duke University Medical Center, Durham, North Carolina 27710 (United States); Lee, Chang-Lung [Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina 27710 (United States); Kirsch, David G. [Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina 27710 and Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina 27710 (United States)

    2015-11-15

    problem using the split Bregman method and GPU-based implementations of backprojection, reprojection, and kernel regression. Using a preclinical mouse model, the authors apply the proposed algorithm to study myocardial injury following radiation treatment of breast cancer. Results: Quantitative 5D simulations are performed using the MOBY mouse phantom. Twenty data sets (ten cardiac phases, two energies) are reconstructed with 88 μm, isotropic voxels from 450 total projections acquired over a single 360° rotation. In vivo 5D myocardial injury data sets acquired in two mice injected with gold and iodine nanoparticles are also reconstructed with 20 data sets per mouse using the same acquisition parameters (dose: ∼60 mGy). For both the simulations and the in vivo data, the reconstruction quality is sufficient to perform material decomposition into gold and iodine maps to localize the extent of myocardial injury (gold accumulation) and to measure cardiac functional metrics (vascular iodine). Their 5D CT imaging protocol represents a 95% reduction in radiation dose per cardiac phase and energy and a 40-fold decrease in projection sampling time relative to their standard imaging protocol. Conclusions: Their 5D CT data acquisition and reconstruction protocol efficiently exploits the rank-sparse nature of spectral and temporal CT data to provide high-fidelity reconstruction results without increased radiation dose or sampling time.

  11. Spectrotemporal CT data acquisition and reconstruction at low dose

    International Nuclear Information System (INIS)

    problem using the split Bregman method and GPU-based implementations of backprojection, reprojection, and kernel regression. Using a preclinical mouse model, the authors apply the proposed algorithm to study myocardial injury following radiation treatment of breast cancer. Results: Quantitative 5D simulations are performed using the MOBY mouse phantom. Twenty data sets (ten cardiac phases, two energies) are reconstructed with 88 μm, isotropic voxels from 450 total projections acquired over a single 360° rotation. In vivo 5D myocardial injury data sets acquired in two mice injected with gold and iodine nanoparticles are also reconstructed with 20 data sets per mouse using the same acquisition parameters (dose: ∼60 mGy). For both the simulations and the in vivo data, the reconstruction quality is sufficient to perform material decomposition into gold and iodine maps to localize the extent of myocardial injury (gold accumulation) and to measure cardiac functional metrics (vascular iodine). Their 5D CT imaging protocol represents a 95% reduction in radiation dose per cardiac phase and energy and a 40-fold decrease in projection sampling time relative to their standard imaging protocol. Conclusions: Their 5D CT data acquisition and reconstruction protocol efficiently exploits the rank-sparse nature of spectral and temporal CT data to provide high-fidelity reconstruction results without increased radiation dose or sampling time

  12. The reconstruction of inflationary potentials

    Science.gov (United States)

    Lin, Jianmang; Gao, Qing; Gong, Yungui

    2016-07-01

    The observational data on the anisotropy of the cosmic microwave background constraints the scalar spectral tilt ns and the tensor to scalar ratio r which depend on the first and second derivatives of the inflaton potential. The information can be used to reconstruct the inflaton potential in the polynomial form up to some orders. However, for some classes of potentials, ns and r behave as ns(N) and r(N) universally in terms of the number of e-folds N. The universal behaviour of ns(N) can be used to reconstruct a class of inflaton potentials. By parametrizing one of the parameters ns(N), ɛ(N) and φ(N), and fitting the parameters in the models to the observational data, we obtain the constraints on the parameters and reconstruct the classes of the inflationary models which include the chaotic inflation, T-model, hilltop inflation, s-dual inflation, natural inflation and R2 inflation.

  13. Network reconstruction from infection cascades

    CERN Document Server

    Braunstein, Alfredo

    2016-01-01

    Reconstructing propagation networks from observations is a fundamental inverse problem, and it's crucial to understand and control dynamics in complex systems. Here we show that it is possible to reconstruct the whole structure of an interaction network and to simultaneously infer the complete time course of activation spreading, relying just on single snapshots of a small number of activity cascades. The method, that we called Inverse Dynamics Network Reconstruction (IDNR), is shown to work successfully on several synthetic and real networks, inferring the networks and the sources of infection based on sparse observations, including single snapshots. IDNR is built on a Belief Propagation approximation, that has an impressive performance in a wide variety of topological structures. The method can be applied in absence of complete time-series data by providing a detailed modeling of the posterior distribution of trajectories conditioned to the observations. Furthermore, we show by experiments that the informat...

  14. Reconstructing Ancient Forms of Life

    Science.gov (United States)

    Benner, Steven A.

    1998-01-01

    Progress in the past three months has occurred in two areas, reconstruction of ancestral proteins and improved understanding of chemical features that are likely to be universal in generic matter regardless of its genesis. Ancestral ribonucleases have been reconstructed, and an example has been developed that shows how physiological function can be assigned to in vitro behaviors observed in biological systems. Sequence data have been collected to permit the reconstruction of src homology 2 domains that underwent radiative divergence at the time of the radiative divergence of chordates. New studies have been completed that show how genetic matter (or its remnants) might be detected on Mars (or other non-terrean locations.) Last, the first in vitro selection experiments have been completed using a nucleoside library carrying positively charged functionality, illustrating the importance of non-standard nucleotides to those attempting to obtain evidence for an "RNA world" as an early episode of life on earth.

  15. The Local Front Reconstruction Method for direct simulation of two- and three-dimensional multiphase flows

    Science.gov (United States)

    Shin, Seungwon; Yoon, Ikroh; Juric, Damir

    2011-07-01

    We present a new interface reconstruction technique, the Local Front Reconstruction Method (LFRM), for incompressible multiphase flows. This new method falls in the category of Front Tracking methods but it shares automatic topology handling characteristics of the previously proposed Level Contour Reconstruction Method (LCRM). The LFRM tracks the phase interface explicitly as in Front Tracking but there is no logical connectivity between interface elements thus greatly easing the algorithmic complexity. Topological changes such as interfacial merging or pinch off are dealt with automatically and naturally as in the Level Contour Reconstruction Method. Here the method is described for both two- and three-dimensional flow geometries. The interfacial reconstruction technique in the LFRM differs from that in the LCRM formulation by foregoing using an Eulerian distance field function. Instead, the LFRM uses information from the original interface elements directly to generate the new interface in a mass conservative way thus showing significantly improved local mass conservation. Because the reconstruction procedure is independently carried out in each individual reconstruction cell after an initial localization process, an adaptive reconstruction procedure can be easily implemented to increase the accuracy while at the same time significantly decreasing the computational time required to perform the reconstruction. Several benchmarking tests are performed to validate the improved accuracy and computational efficiency as compared to the LCRM. The results demonstrate superior performance of the LFRM in maintaining detailed interfacial shapes and good local mass conservation especially when using low-resolution Eulerian grids.

  16. Super-resolution Phase Tomography

    KAUST Repository

    Depeursinge, Christian D.

    2013-04-21

    Digital Holographic Microscopy (DHM) yields reconstructed complex wavefields. It allows synthesizing the aperture of a virtual microscope up to 2π, offering super-resolution phase images. Live images of micro-organisms and neurons with resolution less than 100 nm are presented.

  17. Shape Reconstruction from Generalized Projections

    Science.gov (United States)

    Viikinkoski, Matti

    2016-01-01

    In this thesis we develop methods for recovering the three-dimensional shape of an object from generalized projections. We particularly focus on the problems encountered when data are presented as discrete image fields. We demonstrate the usefulness of the Fourier transform in transferring the image data and shape model projections to a domain more suitable for gradient based optimization. To substantiate the general applicability of our methods to observational astronomy, we reconstruct shape models for several asteroids observed with adaptive optics, thermal infrared interferometry, or range-Doppler radar. The reconstructions are carried out with the ADAM software package that we have designed for general use.

  18. Reconstructing WKB from topological recursion

    CERN Document Server

    Bouchard, Vincent

    2016-01-01

    We prove that the topological recursion reconstructs the WKB expansion of a quantum curve for all spectral curves whose Newton polygons have no interior point (and that are smooth as affine curves). This includes nearly all previously known cases in the literature, and many more; in particular, it includes many quantum curves of order greater than two. We also explore the connection between the choice of ordering in the quantization of the spectral curve and the choice of integration divisor to reconstruct the WKB expansion.

  19. Autoadaptive phase-correlated (AAPC) reconstruction for 4D CBCT

    OpenAIRE

    Bergner, Frank; Berkus, Timo; Oelhafen, Markus; Kunz, Patrik; Pan, Tinsu; Kachelrieß, Marc

    2009-01-01

    Purpose: Kilovoltage cone-beam computed tomography (CBCT) is widely used in image-guided radiation therapy for exact patient positioning prior to the treatment. However, producing time series of volumetric images (4D CBCT) of moving anatomical structures remains challenging. The presented work introduces a novel method, combining high temporal resolution inside anatomical regions with strong motion and image quality improvement in regions with little motion.

  20. A Generalized Bidiagonal-Tikhonov Method Applied To Differential Phase Contrast Tomography

    OpenAIRE

    Schenkels, Nick; Sijbers, Jan; van Aarle, Wim; Vanroose, Wim

    2015-01-01

    Phase contrast tomography is an alternative to classic absorption contrast tomography that leads to higher contrast reconstructions in many applications. We review how phase contrast data can be acquired by using a combination of phase and absorption gratings. Using algebraic reconstruction techniques the object can be reconstructed from the measured data. In order to solve the resulting linear system we propose the Generalized Bidiagonal Tikhonov (GBiT) method, an adaptation of the generaliz...

  1. Cosine-modulated FIR filter banks satisfying perfect reconstruction

    OpenAIRE

    Koilpillai, R. David; Vaidyanathan, P.P.

    1992-01-01

    The authors obtain a necessary and sufficient condition on the 2M (M = number of channels) polyphase components of a linear-phase prototype filter of length N = 2mM (where m = an arbitrary positive integer), such that the polyphase component matrix of the modulated filter is lossless. The losslessness of the polyphase component matrix, in turn, is sufficient to ensure that the analysis/synthesis system satisfies perfect reconstruction (PR). Using this result, a novel design procedure is prese...

  2. Time-based vertex reconstruction in the Compact Muon Solenoid

    OpenAIRE

    Bartlett, Benjamin C.; Gray, Lindsey; Bornheim, Adolf; Spiropulu, María

    2015-01-01

    The Phase-II upgrades to the Large Hadron Collider will introduce a variety of new measurement devices to the CMS, including the High-Granularity Calorimeter (HGCAL). The increase in luminosity from these upgrades will also have the undesired side effect of vastly increasing pileup to a level at which the current machine learning vertex reconstruction (vertexing) algorithms cease to be effective. This will necessitate the development of further vertexing algorithms. Using high precision timin...

  3. GPU-based Low-dose 4DCT Reconstruction via Temporal Non-local Means

    CERN Document Server

    Tian, Zhen; Jiang, Steve B

    2010-01-01

    Four-dimensional computed tomography (4DCT) has been widely used in cancer radiotherapy for accurate target delineation and motion measurement for tumors in thorax and upper abdomen areas. However, 4DCT simulation is associated with much higher imaging dose than conventional CT simulation, which is a major concern in its clinical application. Conventionally, each phase of 4DCT is reconstructed independently using the filtered backprojection (FBP) algorithm. The basic idea of our new algorithm is that, by utilizing the common information among different phases, the input information required to reconstruct image of high quality, and thus the imaging dose, can be reduced. We proposed a temporal non-local means (TNLM) method to explore the inter-phase similarity. All phases of the 4DCT images are reconstructed simultaneously by minimizing a cost function consisting of a data fidelity term and a TNLM regularization term. We utilized a forward-backward splitting algorithm and a Gauss-Jacobi iteration method to eff...

  4. Exact Reconstruction for Near-Field Three-Dimensional Planar Millimeter-Wave Holographic Imaging

    Science.gov (United States)

    Qiao, Lingbo; Wang, Yingxin; Zhao, Ziran; Chen, Zhiqiang

    2015-12-01

    In this paper, an exact reconstruction formula is presented for near-field three-dimensional (3D) planar millimeter-wave (MMW) holographic imaging. The proposed formula is derived based on scalar diffraction theory, and the round-trip imaging process is equivalent to a unidirectional optical field propagation. Because of compensating the propagation loss of the source for the near-field imaging configuration, the inconsistency in range domain of the reconstructed 3D images is avoided. The proposed reconstruction formula also gives a phase correction for the reconstructed complex-valued reflectivity of the target and the range coordinate can be exactly determined. Simulations and laboratory imaging experiments are performed to demonstrate the effectiveness of the proposed reconstruction formula.

  5. Paleoenvironmental reconstruction using microfossils : terrestrial

    International Nuclear Information System (INIS)

    The following section provides a brief summary of the use of pollen and chironomids in terrestrial paleoenvironmental reconstruction and lists some key references and general text addressing the history, methods and development of these techniques in Quaternary paleoclimate research and their application in New Zealand. (author). 52 refs., 8 figs

  6. Reconstructing Indo-European Syllabification

    Science.gov (United States)

    Byrd, Andrew Miles

    2010-01-01

    The chief concern of this dissertation is to investigate a fundamental, yet unsolved problem within the phonology of Proto-Indo-European (PIE): the process of syllabification. I show that by analyzing the much more easily reconstructable word-edge clusters we may predict which types of consonant clusters can occur word-medially, provided that we…

  7. A survey of urban reconstruction

    KAUST Repository

    Musialski, Przemyslaw

    2013-05-10

    This paper provides a comprehensive overview of urban reconstruction. While there exists a considerable body of literature, this topic is still under active research. The work reviewed in this survey stems from the following three research communities: computer graphics, computer vision and photogrammetry and remote sensing. Our goal is to provide a survey that will help researchers to better position their own work in the context of existing solutions, and to help newcomers and practitioners in computer graphics to quickly gain an overview of this vast field. Further, we would like to bring the mentioned research communities to even more interdisciplinary work, since the reconstruction problem itself is by far not solved. This paper provides a comprehensive overview of urban reconstruction. While there exists a considerable body of literature, this topic is still under active research. The work reviewed in this survey stems from the following three research communities: computer graphics, computer vision and photogrammetry and remote sensing. Our goal is to provide a survey that will help researchers to better position their own work in the context of existing solutions, and to help newcomers and practitioners in computer graphics to quickly gain an overview of this vast field. Further, we would like to bring the mentioned research communities to even more interdisciplinary work, since the reconstruction problem itself is by far not solved. © 2013 The Eurographics Association and John Wiley & Sons Ltd.

  8. Breast Reconstruction with Tissue Expansion

    Medline Plus

    Full Text Available RECONSTRUCTIVE BREAST SURGERY ALBANY MEDICAL CENTER HOSPITAL ALBANY, NY July 31, 2008 00:00:10 ANNOUNCER: Welcome to this OR-Live webcast presentation, brought to ... webcast screen and open the door to informed medical care. 00:00:28 DIMITRI KOUMANIS, M.D.: ...

  9. Tomographic reconstruction of polar plumes

    Science.gov (United States)

    Auchère, F.; Guennou, C.; Barbey, N.

    2012-06-01

    We present a tomographic reconstruction of polar plumes as observed in the Extreme Ultraviolet in January 2010. Plumes are elusive structures visible in polar coronal holes that may play an important role in the acceleration of the solar wind. However, despite numerous observations, little is irrefutably known about them. Because of line of sight effects, even their geometry is subject to debate. Are they genuine cylindrical features of the corona or are they only chance alignments along the line of sight? Tomography provides a means to reconstruct the volume of an optically thin object from a set of observations taken from different vantage points. In the case of the Sun, these are typically obtained by using a solar rotation worth of images, which limits the ability to reconstruct short lived structures. We present here a tomographic inversion of the solar corona obtained using only 6 days of data. This is achieved by using simultaneously three space telescopes (EUVI/STEREO and SWAP/PROBA2) in a very specific orbital configuration. The result is the shortest possible tomographic snapshot of polar plumes. The 3D reconstruction shows both quasi-cylindrical plumes and a network pattern that can mimic them by line of sight superimpositions. This suggests that the controversy on plume geometry is due to the coexistence of both types of structures.

  10. Stability indicators in network reconstruction.

    Science.gov (United States)

    Filosi, Michele; Visintainer, Roberto; Riccadonna, Samantha; Jurman, Giuseppe; Furlanello, Cesare

    2014-01-01

    The number of available algorithms to infer a biological network from a dataset of high-throughput measurements is overwhelming and keeps growing. However, evaluating their performance is unfeasible unless a 'gold standard' is available to measure how close the reconstructed network is to the ground truth. One measure of this is the stability of these predictions to data resampling approaches. We introduce NetSI, a family of Network Stability Indicators, to assess quantitatively the stability of a reconstructed network in terms of inference variability due to data subsampling. In order to evaluate network stability, the main NetSI methods use a global/local network metric in combination with a resampling (bootstrap or cross-validation) procedure. In addition, we provide two normalized variability scores over data resampling to measure edge weight stability and node degree stability, and then introduce a stability ranking for edges and nodes. A complete implementation of the NetSI indicators, including the Hamming-Ipsen-Mikhailov (HIM) network distance adopted in this paper is available with the R package nettools. We demonstrate the use of the NetSI family by measuring network stability on four datasets against alternative network reconstruction methods. First, the effect of sample size on stability of inferred networks is studied in a gold standard framework on yeast-like data from the Gene Net Weaver simulator. We also consider the impact of varying modularity on a set of structurally different networks (50 nodes, from 2 to 10 modules), and then of complex feature covariance structure, showing the different behaviours of standard reconstruction methods based on Pearson correlation, Maximum Information Coefficient (MIC) and False Discovery Rate (FDR) strategy. Finally, we demonstrate a strong combined effect of different reconstruction methods and phenotype subgroups on a hepatocellular carcinoma miRNA microarray dataset (240 subjects), and we validate the

  11. Stability indicators in network reconstruction.

    Directory of Open Access Journals (Sweden)

    Michele Filosi

    Full Text Available The number of available algorithms to infer a biological network from a dataset of high-throughput measurements is overwhelming and keeps growing. However, evaluating their performance is unfeasible unless a 'gold standard' is available to measure how close the reconstructed network is to the ground truth. One measure of this is the stability of these predictions to data resampling approaches. We introduce NetSI, a family of Network Stability Indicators, to assess quantitatively the stability of a reconstructed network in terms of inference variability due to data subsampling. In order to evaluate network stability, the main NetSI methods use a global/local network metric in combination with a resampling (bootstrap or cross-validation procedure. In addition, we provide two normalized variability scores over data resampling to measure edge weight stability and node degree stability, and then introduce a stability ranking for edges and nodes. A complete implementation of the NetSI indicators, including the Hamming-Ipsen-Mikhailov (HIM network distance adopted in this paper is available with the R package nettools. We demonstrate the use of the NetSI family by measuring network stability on four datasets against alternative network reconstruction methods. First, the effect of sample size on stability of inferred networks is studied in a gold standard framework on yeast-like data from the Gene Net Weaver simulator. We also consider the impact of varying modularity on a set of structurally different networks (50 nodes, from 2 to 10 modules, and then of complex feature covariance structure, showing the different behaviours of standard reconstruction methods based on Pearson correlation, Maximum Information Coefficient (MIC and False Discovery Rate (FDR strategy. Finally, we demonstrate a strong combined effect of different reconstruction methods and phenotype subgroups on a hepatocellular carcinoma miRNA microarray dataset (240 subjects, and we

  12. Ancestral reconstruction of tick lineages.

    Science.gov (United States)

    Mans, Ben J; de Castro, Minique H; Pienaar, Ronel; de Klerk, Daniel; Gaven, Philasande; Genu, Siyamcela; Latif, Abdalla A

    2016-06-01

    Ancestral reconstruction in its fullest sense aims to describe the complete evolutionary history of a lineage. This depends on accurate phylogenies and an understanding of the key characters of each parental lineage. An attempt is made to delineate our current knowledge with regard to the ancestral reconstruction of the tick (Ixodida) lineage. Tick characters may be assigned to Core of Life, Lineages of Life or Edges of Life phenomena depending on how far back these characters may be assigned in the evolutionary Tree of Life. These include housekeeping genes, sub-cellular systems, heme processing (Core of Life), development, moulting, appendages, nervous and organ systems, homeostasis, respiration (Lineages of Life), specific adaptations to a blood-feeding lifestyle, including the complexities of salivary gland secretions and tick-host interactions (Edges of Life). The phylogenetic relationships of lineages, their origins and importance in ancestral reconstruction are discussed. Uncertainties with respect to systematic relationships, ancestral reconstruction and the challenges faced in comparative transcriptomics (next-generation sequencing approaches) are highlighted. While almost 150 years of information regarding tick biology have been assembled, progress in recent years indicates that we are in the infancy of understanding tick evolution. Even so, broad reconstructions can be made with relation to biological features associated with various lineages. Conservation of characters shared with sister and parent lineages are evident, but appreciable differences are present in the tick lineage indicating modification with descent, as expected for Darwinian evolutionary theory. Many of these differences can be related to the hematophagous lifestyle of ticks. PMID:26868413

  13. Application of three-dimensional digital image processing for reconstruction of microstructural volume from serial sections

    Energy Technology Data Exchange (ETDEWEB)

    Tewari, A.; Gokhale, A.M.

    2000-03-01

    Three-dimensional digital image processing is useful for reconstruction of microstructural volume from a stack of serial sections. Application of this technique is demonstrated via reconstruction of a volume segment of the liquid-phase sintered microstructure of a tungsten heavy alloy processed in the microgravity environment of NASA's space shuttle, Columbia. Ninety serial sections (approximately one micrometer apart) were used for reconstruction of the three-dimensional microstructure. The three-dimensional microstructural reconstruction clearly revealed that the tungsten grains are almost completely connected in three-dimensional space. Both the matrix and the grains are topologically co-continuous, although the alloy was liquid-phase sintered in microgravity. Therefore, absence of gravity did not produced a microstructure consisting of discrete isolated W grains uniformly dispersed in the liquid Ni-Fe alloy matrix at the sintering temperature.

  14. Dose reconstruction studies at selected nuclear weapons facilities in the USA

    International Nuclear Information System (INIS)

    The Centers for Disease Control and Prevention (CDC) is involved in dose reconstructions at six nuclear weapons facilities in the United States. CDC is directly responsible for the conduct of four of these studies, and it provides technical support for the other two. We expect that the two most recently initiated studies will be conducted in five phases: retrieval and assessment of data, initial source term development and pathway analysis, screening dose and exposure calculations, development of methods for assessing environmental dose, and calculation of environmental doses and exposures. In addition to these technical phases of the studies, significant public involvement will be an integral part of the dose reconstruction process. In this paper, we review the status of the current dose reconstructions and discuss CDC's approach to dose reconstruction. (author). 8 refs, 1 fig., 2 tabs

  15. Oak Ridge Dose Reconstruction Project Summary Report; Reports of the Oak Ridge Dose Reconstruction, Vol. 7

    International Nuclear Information System (INIS)

    In the early 1990s, concern about the Oak Ridge Reservation's past releases of contaminants to the environment prompted Tennessee's public health officials to pursue an in-depth study of potential off-site health effects at Oak Ridge. This study, the Oak Ridge dose reconstruction, was supported by an agreement between the U.S. Department of Energy (DOE) and the State of Tennessee, and was overseen by a 12-member panel of individuals appointed by Tennessee's Commissioner of Health. The panel requested that the principal investigator for the project prepare the following report, ''Oak Ridge Dose Reconstruction Project Summary Report,'' to serve the following purposes: (1) summarize in a single, less technical report, the methods and results of the various investigations that comprised the Phase II of the dose reconstruction; (2) describe the systematic searching of classified and unclassified historical records that was a vital component of the project; and (3) summarize the less detailed, screening-level assessments that were performed to evaluate the potential health significance of a number of materials, such a uranium, whose priority did not require a complete dose reconstruction effort. This report describes each major step of the dose reconstruction study: (1) the review of thousands of historical records to obtain information relating to past operations at each facility; (2) estimation of the quantity and timing of releases of radioiodines from X-10, of mercury from Y-12, of PCB's from all facilities, and of cesium-137 and other radionuclides from White Oak Creek; (3) evaluation of the routes taken by these contaminants through the environment to nearby populations; and (4) estimation of doses and health risks to exposed groups. Calculations found the highest excess cancer risks for a female born in 1952 who drank goat milk; the highest non-cancer health risk was for children in a farm family exposed to PCBs in and near East Fork Poplar Creek. More detailed

  16. COMPARISON OF HOLOGRAPHIC AND ITERATIVE METHODS FOR AMPLITUDE OBJECT RECONSTRUCTION

    Directory of Open Access Journals (Sweden)

    I. A. Shevkunov

    2015-01-01

    Full Text Available Experimental comparison of four methods for the wavefront reconstruction is presented. We considered two iterative and two holographic methods with different mathematical models and algorithms for recovery. The first two of these methods do not use a reference wave recording scheme that reduces requirements for stability of the installation. A major role in phase information reconstruction by such methods is played by a set of spatial intensity distributions, which are recorded as the recording matrix is being moved along the optical axis. The obtained data are used consistently for wavefront reconstruction using an iterative procedure. In the course of this procedure numerical distribution of the wavefront between the planes is performed. Thus, phase information of the wavefront is stored in every plane and calculated amplitude distributions are replaced for the measured ones in these planes. In the first of the compared methods, a two-dimensional Fresnel transform and iterative calculation in the object plane are used as a mathematical model. In the second approach, an angular spectrum method is used for numerical wavefront propagation, and the iterative calculation is carried out only between closely located planes of data registration. Two digital holography methods, based on the usage of the reference wave in the recording scheme and differing from each other by numerical reconstruction algorithm of digital holograms, are compared with the first two methods. The comparison proved that the iterative method based on 2D Fresnel transform gives results comparable with the result of common holographic method with the Fourier-filtering. It is shown that holographic method for reconstructing of the object complex amplitude in the process of the object amplitude reduction is the best among considered ones.

  17. Cubic to tetragonal crystal lattice reconstruction during ordering or decomposition

    Energy Technology Data Exchange (ETDEWEB)

    Cheong, Byung-kl [Carnegie-Mellon Univ., Pittsburgh, PA (United States). Dept. of Materials Science and Engineering

    1992-09-01

    This thesis studied thermodynamic stability and morphology of product phases in diffusional phase transformations involving cubic-to-tetragonal crystal lattice reconstructions. Two different kinds of diffusional transformations were examined: L1{sub 0} ordering (fcc to fct lattice change) and decomposition of off-stoichiometric B2 ordering alloys accompanying bcc to fcc Bain transformation. In the first case, Fe-45 at.% Pd alloys were studied by TEM; in the second, the Bain strain relaxation during decomposition of hyper-eutectoid Cu-9.04 wt% Be alloy was studied. CuAu and InMg were also studied.

  18. Reconstructing the inflaton potential: Perturbative reconstruction to second order

    Energy Technology Data Exchange (ETDEWEB)

    Copeland, Edmund J.; Kolb, Edward W.; Liddle, Andrew R.; Lidsey, James E.

    1993-08-01

    One method to reconstruct the scalar field potential of inflation is a perturbative approach, where the values of the potential and its derivatives are calculated as an expansion in departures from the slow-roll approximation. They can then be expressed in terms of observable quantities, such as the square of the ratio of the gravitational wave amplitude to the density perturbation amplitude, the deviation of the spectral index from the Harrison--Zel'dovich value, etc. Here, we calculate complete expressions for the second-order contributions to the coefficients of the expansion by including for the first time corrections to the standard expressions for the perturbation spectra. As well as offering an improved result, these corrections indicate the expected accuracy of the reconstruction. Typically the corrections are only a few percent.

  19. Current Trends in Anterior Cruciate Ligament Reconstruction

    OpenAIRE

    Kim, Ha Sung; Seon, Jong Keun; Jo, Ah Reum

    2013-01-01

    The advances in the knowledge of anatomy, surgical techniques, and fixation devices have led to the improvement of anterior cruciate ligament (ACL) reconstruction over the past 10 years. Nowadays, double bundle and anatomical single bundle ACL reconstruction that more closely restores the normal anatomy of the ACL are becoming popular. Although there is still no definite conclusion whether double bundle ACL reconstruction provides better clinical results than single bundle reconstruction, the...

  20. 3D Reconstruction Technique for Tomographic PIV

    Institute of Scientific and Technical Information of China (English)

    姜楠; 包全; 杨绍琼

    2015-01-01

    Tomographic particle image velocimetry(Tomo-PIV) is a state-of-the-art experimental technique based on a method of optical tomography to achieve the three-dimensional(3D) reconstruction for three-dimensional three-component(3D-3C) flow velocity measurements. 3D reconstruction for Tomo-PIV is carried out herein. Meanwhile, a 3D simplified tomographic reconstruction model reduced from a 3D volume light inten-sity field with 2D projection images into a 2D Tomo-slice plane with 1D projecting lines, i.e., simplifying this 3D reconstruction into a problem of 2D Tomo-slice plane reconstruction, is applied thereafter. Two kinds of the most well-known algebraic reconstruction techniques, algebraic reconstruction technique(ART) and multiple algebraic reconstruction technique(MART), are compared as well. The principles of the two reconstruction algorithms are discussed in detail, which has been performed by a series of simulation images, yielding the corresponding recon-struction images that show different features between the ART and MART algorithm, and then their advantages and disadvantages are discussed. Further discussions are made for the standard particle image reconstruction when the background noise of the pre-initial particle image has been removed. Results show that the particle image recon-struction has been greatly improved. The MART algorithm is much better than the ART. Furthermore, the computa-tional analyses of two parameters(the particle density and the number of cameras), are performed to study their effects on the reconstruction. Lastly, the 3D volume particle field is reconstructed by using the improved algorithm based on the simplified 3D tomographic reconstruction model, which proves that the algorithm simplification is feasible and it can be applied to the reconstruction of 3D volume particle field in a Tomo-PIV system.

  1. Multi-resolution Compressive Sensing Reconstruction

    OpenAIRE

    Gonzalez, Adriana; Jiang, Hong; Huang, Gang; Jacques, Laurent

    2016-01-01

    We consider the problem of reconstructing an image from compressive measurements using a multi-resolution grid. In this context, the reconstructed image is divided into multiple regions, each one with a different resolution. This problem arises in situations where the image to reconstruct contains a certain region of interest (RoI) that is more important than the rest. Through a theoretical analysis and simulation experiments we show that the multi-resolution reconstruction provides a higher ...

  2. Magni: A Python Package for Compressive Sampling and Reconstruction of Atomic Force Microscopy Images

    Directory of Open Access Journals (Sweden)

    Christian Schou Oxvig

    2014-10-01

    Full Text Available Magni is an open source Python package that embraces compressed sensing and Atomic Force Microscopy (AFM imaging techniques. It provides AFM-specific functionality for undersampling and reconstructing images from AFM equipment and thereby accelerating the acquisition of AFM images. Magni also provides researchers in compressed sensing with a selection of algorithms for reconstructing undersampled general images, and offers a consistent and rigorous way to efficiently evaluate the researchers own developed reconstruction algorithms in terms of phase transitions. The package also serves as a convenient platform for researchers in compressed sensing aiming at obtaining a high degree of reproducibility of their research.

  3. The reconstruction of diffractive object digital hologram at a short distance

    Institute of Scientific and Technical Information of China (English)

    Liyun Zhong(钟丽云); Yimo Zhang(张以谟); Xiaoxu L(u)(吕晓旭); Caojin Yuan(袁操今)

    2004-01-01

    By using a spherical wave as the reference wave, we recorded the in-line phase-shifting digital hologram of the 25th element of Chinese standard No. 3 resolution test pattern, and gave the corresponding numerical reconstructed results. Some problems concerning with the digital hologram recording and reconstruction of the diffractive object at a short distance are discussed. The experimental result shows that the resolution of the reconstructed image is better than 10μm, which is the limit by using this experimental arrangement.

  4. The reconstruction of diffractive object digital hologram at a short distance

    Institute of Scientific and Technical Information of China (English)

    钟丽云; 张以谟; 吕晓旭; 袁操今

    2004-01-01

    By using a spherical wave as the reference wave, we recorded the in-line phase-shifting digital hologram of the 25th element of Chinese standard No. 3 resolution test pattern, and gave the corresponding numerical reconstructed results. Some problems concerning with the digital hologram recording and reconstruction of the diffractive object at a short distance are discussed. The experimental result shows that the resolution of the reconstructed image is better than 10 μm, which is the limit by using this experimental arrangement.

  5. Shift Multiplex Recording of Four-Valued Phase Data Pages by Volume Retardagraphy

    Directory of Open Access Journals (Sweden)

    Daisuke Barada

    2014-04-01

    Full Text Available In this paper, shift multiplex recording of phase data pages on a volume polarization-sensitive medium by retardagraphy is demonstrated. The origin of shift selectivity in volume retardagraphy is explained. In the experiment, four-valued phase data pages are used. Then, a coding method is proposed to correct a reconstructed phase pattern. The recorded phase data pages are reconstructed using the feature of the coding method. By comparing the reconstructed phase data pages with recording phase data pages, symbol error rates of less than 11% are achieved. From the experimental result, it is verified that volume retardagraphy is applicable to optical memory.

  6. Quantitative neutron phase contrast tomography

    International Nuclear Information System (INIS)

    Conventional neutron radiography and tomography are based on the attenuation contrast induced by the sample. In the last few years, another source of image contrast, the so-called phase contrast, has been introduced. The imaging methods to detect phase changes due to the interaction with the sample improve continuously, and several techniques are established. One method to discover phase shifts is diffraction enhanced imaging using a double-crystal diffractometer. It is described how the refractive index distribution of a sample can be recovered quantitatively in tomographic reconstructions from data achieved by this technique. Using reference samples with a well-known refractive index distribution, high accuracy with deviations of only a few per cent could be found in the reconstructions for all used materials

  7. Reconstructing Deweyan Pragmatism: A Review Essay

    Science.gov (United States)

    Neubert, Stefan

    2009-01-01

    In this essay Stefan Neubert argues that John Dewey was a philosopher of reconstruction and that the best use we can make of him today is to reconstruct his work in and for our own contexts. Neubert distinguishes three necessary and equally important components of the overall project of reconstructing Deweyan pragmatism: first, to make strong and…

  8. Set-reconstructibility of Post classes

    OpenAIRE

    Couceiro, Miguel; Lehtonen, Erkko; Schölzel, Karsten

    2013-01-01

    The clones of Boolean functions are classified in regard to set-reconstructibility via a strong dichotomy result: the clones containing only affine functions, conjunctions, disjunctions or constant functions are set-reconstructible, whereas the remaing clones are not weakly reconstructible.

  9. Effects of grinding-induced grain boundary and interfaces on electrical transportation and structure phase transition in ZnSe under high pressure

    Science.gov (United States)

    Jie, Yang; Pei, Wang; Guo-Zhao, Zhang; Xiao-Xue, Zhou; Jing, Li; Cai-Long, Liu

    2016-06-01

    Interface and scale effects are the two most important factors which strongly affect the structure and the properties of nano-/micro-crystals under pressure. We conduct an experiment under high pressure in situ alternating current impedance to elucidate the effects of interface on the structure and electrical transport behavior of two ZnSe samples with different sizes obtained by physical grinding. The results show that (i) two different-sized ZnSe samples undergo the same phase transitions from zinc blend to cinnabar-type phase and then to rock salt phase; (ii) the structural transition pressure of the 859-nm ZnSe sample is higher than that of the sample of 478 nm, which indicates the strong scale effect. The pressure induced boundary resistance change is obtained by fitting the impedance spectrum, which shows that the boundary conduction dominates the electrical transport behavior of ZnSe in the whole experimental pressure range. By comparing the impedance spectra of two different-sized ZnSe samples at high pressure, we find that the resistance of the 478-nm ZnSe sample is lower than that of the 859-nm sample, which illustrates that the sample with smaller particle size has more defects which are due to physical grinding. Project supported by the National Natural Science Foundation of China (Grant Nos. 11404133 and 11374121) and the Program of Science and Technology Development Plan of Jilin Province, China (Grant No. 20140520105JH).

  10. Dual-source CT coronary imaging in heart transplant recipients: image quality and optimal reconstruction interval

    Energy Technology Data Exchange (ETDEWEB)

    Bastarrika, Gorka; Arraiza, Maria; Pueyo, Jesus C. [Clinica Universitaria, Universidad de Navarra, Department of Radiology, Pamplona (Spain); Cecco, Carlo N. de [Universita' di Roma ' ' Sapienza' ' -Ospedale Sant' Andrea, Department of Radiology, Rome (Italy); Ubilla, Matias; Mastrobuoni, Stefano; Rabago, Gregorio [Clinica Universitaria, Universidad de Navarra, Department of Cardiovascular Surgery, Pamplona (Spain)

    2008-09-15

    The image quality and optimal reconstruction interval for coronary arteries in heart transplant recipients undergoing non-invasive dual-source computed tomography (DSCT) coronary angiography was evaluated. Twenty consecutive heart transplant recipients who underwent DSCT coronary angiography were included (19 male, one female; mean age 63.1{+-}10.7 years). Data sets were reconstructed in 5% steps from 30% to 80% of the R-R interval. Two blinded independent observers assessed the image quality of each coronary segments using a five-point scale (from 0 = not evaluative to 4=excellent quality). A total of 289 coronary segments in 20 heart transplant recipients were evaluated. Mean heart rate during the scan was 89.1{+-}10.4 bpm. At the best reconstruction interval, diagnostic image quality (score {>=}2) was obtained in 93.4% of the coronary segments (270/289) with a mean image quality score of 3.04{+-} 0.63. Systolic reconstruction intervals provided better image quality scores than diastolic reconstruction intervals (overall mean quality scores obtained with the systolic and diastolic reconstructions 3.03{+-}1.06 and 2.73{+-}1.11, respectively; P<0.001). Different systolic reconstruction intervals (35%, 40%, 45% of RR interval) did not yield to significant differences in image quality scores for the coronary segments (P=0.74). Reconstructions obtained at the systolic phase of the cardiac cycle allowed excellent diagnostic image quality coronary angiograms in heart transplant recipients undergoing DSCT coronary angiography. (orig.)

  11. Image reconstruction for optical tomography using photon density waves

    Energy Technology Data Exchange (ETDEWEB)

    Khalaf, R

    1999-08-01

    Diagnostic imaging makes use of different kinds of radiation. A recent type of imaging using near-infrared light is thought to be a safer and less-expensive method of in-vivo imaging. Near infra-red light can penetrate biological tissue to certain depths. The problem of using near infrared light for imaging, is that the scattering of the photons dominates absorption, causing difficulties in the reconstruction model on which biomedical optical imaging depends crucially. The aim of this thesis is to develop and investigate the performance of a reconstruction algorithm in the frequency domain which allows fast and efficient reconstruction of the image of a limb, or an optical phantom. The forward problem of the propagation of photons inside biological tissue is modelled using the Diffusion Approximation theory solved by the finite element method. Values of DC intensity, phase shift and modulation depth at the boundary as functions of the diffusion and absorption coefficients are given. The inverse model is formulated as a nonlinear least-squares optimisation problem. The Truncated Newton method with Trust region is used to determine the optical properties. Reverse differentiation is used to calculate the error function because of its speed advantage over forward differentiation. A sensitivity analysis is performed to investigate the simultaneous reconstruction of the diffusion and absorption coefficients. The use of a combined error function of DC intensity, phase and modulation prove to be the most successful at recovering the optical parameters. The ability to distinguish between object size and size of optical parameter is also investigated. Contrast, mean and standard deviation are used as measures of the performance of the reconstruction algorithm. A Tikhonov regularisation method was used to improve ill-conditioning and behaviour in the presence of noise. An investigation of the optimal regularisation parameter is undertaken with the addition of noise to the

  12. Image reconstruction for optical tomography using photon density waves

    International Nuclear Information System (INIS)

    Diagnostic imaging makes use of different kinds of radiation. A recent type of imaging using near-infrared light is thought to be a safer and less-expensive method of in-vivo imaging. Near infra-red light can penetrate biological tissue to certain depths. The problem of using near infrared light for imaging, is that the scattering of the photons dominates absorption, causing difficulties in the reconstruction model on which biomedical optical imaging depends crucially. The aim of this thesis is to develop and investigate the performance of a reconstruction algorithm in the frequency domain which allows fast and efficient reconstruction of the image of a limb, or an optical phantom. The forward problem of the propagation of photons inside biological tissue is modelled using the Diffusion Approximation theory solved by the finite element method. Values of DC intensity, phase shift and modulation depth at the boundary as functions of the diffusion and absorption coefficients are given. The inverse model is formulated as a nonlinear least-squares optimisation problem. The Truncated Newton method with Trust region is used to determine the optical properties. Reverse differentiation is used to calculate the error function because of its speed advantage over forward differentiation. A sensitivity analysis is performed to investigate the simultaneous reconstruction of the diffusion and absorption coefficients. The use of a combined error function of DC intensity, phase and modulation prove to be the most successful at recovering the optical parameters. The ability to distinguish between object size and size of optical parameter is also investigated. Contrast, mean and standard deviation are used as measures of the performance of the reconstruction algorithm. A Tikhonov regularisation method was used to improve ill-conditioning and behaviour in the presence of noise. An investigation of the optimal regularisation parameter is undertaken with the addition of noise to the

  13. Effects of ACL Reconstructive Surgery on Temporal Variations of Cytokine Levels in Synovial Fluid

    Science.gov (United States)

    Bigoni, Marco; Gandolla, Marta; Sacerdote, Paola; Piatti, Massimiliano; Castelnuovo, Alberto; Franchi, Silvia; Gorla, Massimo; Munegato, Daniele; Gaddi, Diego; Pedrocchi, Alessandra; Omeljaniuk, Robert J.; Locatelli, Vittorio; Torsello, Antonio

    2016-01-01

    Anterior cruciate ligament (ACL) reconstruction restores knee stability but does not reduce the incidence of posttraumatic osteoarthritis induced by inflammatory cytokines. The aim of this research was to longitudinally measure IL-1β, IL-6, IL-8, IL-10, and TNF-α levels in patients subjected to ACL reconstruction using bone-patellar tendon-bone graft. Synovial fluid was collected within 24–72 hours of ACL rupture (acute), 1 month after injury immediately prior to surgery (presurgery), and 1 month thereafter (postsurgery). For comparison, a “control” group consisted of individuals presenting chronic ACL tears. Our results indicate that levels of IL-6, IL-8, and IL-10 vary significantly over time in reconstruction patients. In the acute phase, the levels of these cytokines in reconstruction patients were significantly greater than those in controls. In the presurgery phase, cytokine levels in reconstruction patients were reduced and comparable with those in controls. Finally, cytokine levels increased again with respect to control group in the postsurgery phase. The levels of IL-1β and TNF-α showed no temporal variation. Our data show that the history of an ACL injury, including trauma and reconstruction, has a significant impact on levels of IL-6, IL-8, and IL-10 in synovial fluid but does not affect levels of TNF-α and IL-1β. PMID:27313403

  14. Quantitative image quality evaluation for cardiac CT reconstructions

    Science.gov (United States)

    Tseng, Hsin-Wu; Fan, Jiahua; Kupinski, Matthew A.; Balhorn, William; Okerlund, Darin R.

    2016-03-01

    Maintaining image quality in the presence of motion is always desirable and challenging in clinical Cardiac CT imaging. Different image-reconstruction algorithms are available on current commercial CT systems that attempt to achieve this goal. It is widely accepted that image-quality assessment should be task-based and involve specific tasks, observers, and associated figures of merits. In this work, we developed an observer model that performed the task of estimating the percentage of plaque in a vessel from CT images. We compared task performance of Cardiac CT image data reconstructed using a conventional FBP reconstruction algorithm and the SnapShot Freeze (SSF) algorithm, each at default and optimal reconstruction cardiac phases. The purpose of this work is to design an approach for quantitative image-quality evaluation of temporal resolution for Cardiac CT systems. To simulate heart motion, a moving coronary type phantom synchronized with an ECG signal was used. Three different percentage plaques embedded in a 3 mm vessel phantom were imaged multiple times under motion free, 60 bpm, and 80 bpm heart rates. Static (motion free) images of this phantom were taken as reference images for image template generation. Independent ROIs from the 60 bpm and 80 bpm images were generated by vessel tracking. The observer performed estimation tasks using these ROIs. Ensemble mean square error (EMSE) was used as the figure of merit. Results suggest that the quality of SSF images is superior to the quality of FBP images in higher heart-rate scans.

  15. Fast phylogeny reconstruction through learning of ancestral sequences

    CERN Document Server

    Mihaescu, Radu; Rao, Satish

    2008-01-01

    Given natural limitations on the length DNA sequences, designing phylogenetic reconstruction methods which are reliable under limited information is a crucial endeavor. There have been two approaches to this problem: reconstructing partial but reliable information about the tree (\\cite{Mo07, DMR08,DHJ06,GMS08}), and reaching "deeper" in the tree through reconstruction of ancestral sequences. In the latter category, \\cite{DMR06} settled an important conjecture of M.Steel, showing that, under the CFN model of evolution, all trees on $n$ leaves with edge lengths bounded by the Ising model phase transition can be recovered with high probability from genomes of length $O(\\log n)$ with a polynomial time algorithm. Their methods had a running time of $O(n^{10})$. Here we enhance our methods from \\cite{DHJ06} with the learning of ancestral sequences and provide an algorithm for reconstructing a sub-forest of the tree which is reliable given available data, without requiring a-priori known bounds on the edge lengths o...

  16. Atmospheric muons reconstruction with Antares

    International Nuclear Information System (INIS)

    The ANTARES collaboration is building a neutrino telescope in the Mediterranean Sea. This detector contains 900 photomultiplier tubes, dispatched on 12 lines, in order to detect Cerenkov light from muon induced by neutrino interactions in the the vicinity of the detector. Currently the first 5 lines have been deployed. A first task consists in studying the stability of the detector calibration, which is a necessary step to understand the detector response. Then we studied optical properties of water, for this we developed a reconstruction method dedicated to LED Beacon. The extracted parameters are compatible with earlier measurements. A quality criteria to reject badly reconstructed track has been developed based on the likelihood of the tracks fit versus point fit. This has been applied to real data and a preliminary analysis of atmospheric muons with a 5-lines detector is performed. (author)

  17. Optimal Reconstruction of Inviscid Vortices

    CERN Document Server

    Danaila, Ionut

    2014-01-01

    This study addresses the question whether, given {some} measurements of the velocity field induced by a vortex, one can stably determine the structure of the vortex. Assuming that the flow is incompressible, inviscid and stationary in the frame of reference moving with the vortex, the "structure" of the vortex is uniquely characterized by the functional relation between the streamfunction and vorticity. It is demonstrated how the inverse problem of reconstructing this functional relation from data can be framed as an optimization problem which can be efficiently solved using variational techniques. To focus attention, we consider 3D axisymmetric vortex rings and use measurements of the tangential velocity on the boundary of the vortex bubble. In contrast to earlier studies, the vorticity function defining the streamfunction-vorticity relation is reconstructed in the continuous setting subject to a minimum number of assumptions. To validate our approach, two test cases are presented, involving Hill's and Norbu...

  18. Reconstruction of complete interval tournaments

    CERN Document Server

    Iványi, Antal

    2010-01-01

    Let $a, b$ and $n$ be nonnegative integers $(b \\geq a, \\ b > 0, \\ n \\geq 1)$, $\\mathcal{G}_n(a,b)$ be a multigraph on $n$ vertices in which any pair of vertices is connected with at least $a$ and at most $b$ edges and \\textbf{v =} $(v_1, v_2, ..., v_n)$ be a vector containing $n$ nonnegative integers. We give a necessary and sufficient condition for the existence of such orientation of the edges of $\\mathcal{G}_n(a,b)$, that the resulted out-degree vector equals to \\textbf{v}. We describe a reconstruction algorithm. In worst case checking of \\textbf{v} requires $\\Theta(n)$ time and the reconstruction algorithm works in $O(bn^3)$ time. Theorems of H. G. Landau (1953) and J. W. Moon (1963) on the score sequences of tournaments are special cases $b = a = 1$ resp. $b = a \\geq 1$ of our result.

  19. 3D reconstruction of porous electrodes and microstructure modelling

    Energy Technology Data Exchange (ETDEWEB)

    Joos, Jochen; Rueger, Bernd; Weber, Andre; Ivers-Tiffee, Ellen [Karlsruher Institute fuer Technologie (KIT), Karlsruhe (DE). Inst. fuer Werkstoffe der Elektrotechnik (IWE); Carraro, Thomas [Heidelberg Univ. (Germany). Inst. fuer Angewandte Mathematik

    2010-07-01

    The performance of a solid oxide fuel cell (SOFC) is limited by electrode polarisation processes, depending both on material composition and microstructure characteristics. To understand and improve electrode performance, a detailed knowledge of the electrode microstructure is essential. Recent developments in 3D image reconstruction combined with Focused Ion Beam (FIB) and Scanning Electron Microscopy (SEM) techniques proved a way to achieve highly detailed microstructural data. From this data the determination of valuable microstructural parameters is possible. The microstructure is commonly described by parameters as volume/porosity fraction, tortuosity of pores/materal (or: tortuosity of electronic and ionic transport in 2-phase materials), three-phase boundary length (electronic conducting electrodes) or electrode surface area (mixed conducting electrodes). Based on these parameters and with the help of adequate models, the electrode performance can be estimated. It is obvious that the accurateness of the model prediction depends on the quality of the parameters. Different groups reported first trials in the reconstruction of SOFC electrodes by FIB/SEM methods. They all used the reconstruction to calculate microstructural parameters. But nevertheless a lot of questions remain, primarily questions concerning the accuracy of the reconstruction or the minimum size of the volume that has to be reconstructed to obtain meaningful results. In this contribution, a ZEISS 1540XB CrossBeam {sup registered} was used to provide over 700 consecutive images of a porous LSCF (La{sub 0.58}Sr{sub 0.4}CO{sub 0.2.}Fe{sub 0.8}O{sub 3-{delta}})-cathode. The calculation of the key microstructural parameters (i) volume/porosity fraction (ii) electrode surface area and (iii) tortuosity of pores and material from 3D FIB/SEM-data will be presented. Additionally the influence of the reconstruction-volume on the calculated parameters will be discussed. Also the presented technique is

  20. Pediatric anterior cruciate ligament reconstruction

    OpenAIRE

    McConkey, Mark O.; Bonasia, Davide Edoardo; Amendola, Annunziato

    2011-01-01

    An increasing number of anterior cruciate ligament (ACL) injuries are seen in children now than in the past due to increased sports participation. The natural history of ACL deficient knees in active individuals, particularly in children is poor. Surgical management of ACL deficiency in children is complex due to the potential risk of injury to the physis and growth disturbance. Delaying ACL reconstruction until maturity is possible but risks instability episodes and intra-articular damage. S...

  1. Computed laminography and reconstruction algorithm

    Science.gov (United States)

    Que, Jie-Min; Cao, Da-Quan; Zhao, Wei; Tang, Xiao; Sun, Cui-Li; Wang, Yan-Fang; Wei, Cun-Feng; Shi, Rong-Jian; Wei, Long; Yu, Zhong-Qiang; Yan, Yong-Lian

    2012-08-01

    Computed laminography (CL) is an alternative to computed tomography if large objects are to be inspected with high resolution. This is especially true for planar objects. In this paper, we set up a new scanning geometry for CL, and study the algebraic reconstruction technique (ART) for CL imaging. We compare the results of ART with variant weighted functions by computer simulation with a digital phantom. It proves that ART algorithm is a good choice for the CL system.

  2. Computed laminography and reconstruction algorithm

    International Nuclear Information System (INIS)

    Computed laminography (CL) is an alternative to computed tomography if large objects are to be inspected with high resolution. This is especially true for planar objects. In this paper, we set up a new scanning geometry for CL, and study the algebraic reconstruction technique (ART) for CL imaging. We compare the results of ART with variant weighted functions by computer simulation with a digital phantom. It proves that ART algorithm is a good choice for the CL system. (authors)

  3. A Reduction of the Graph Reconstruction Conjecture

    Directory of Open Access Journals (Sweden)

    Monikandan S.

    2014-08-01

    Full Text Available A graph is said to be reconstructible if it is determined up to isomor- phism from the collection of all its one-vertex deleted unlabeled subgraphs. Reconstruction Conjecture (RC asserts that all graphs on at least three vertices are reconstructible. In this paper, we prove that interval-regular graphs and some new classes of graphs are reconstructible and show that RC is true if and only if all non-geodetic and non-interval-regular blocks G with diam(G = 2 or diam(Ḡ = diam(G = 3 are reconstructible

  4. Minimonoka Stent for Canalicular Reconstruction

    Directory of Open Access Journals (Sweden)

    Sunil G Biradar,

    2015-04-01

    Full Text Available Objective: Canalicular injuries are relatively common and accounts for 16-26% of all lid tears. There are different techniques for reconstructing traumatic canalicular lacerations. The most favorable intervention would be one that is simple, less invasive with reduced postoperative complications/recovery time. The aim of this study is to report the surgical outcome with the Mini-Monoka monocanalicular stent. Material and Methods: Patients with traumatic canalicular lacerations who underwent surgical reconstruction using the Mini-Monoka monocanalicular stent were included. The surgical outcome was based on subjective (epiphora and objective (tear meniscus level, and lacrimal irrigation findings after stent removal. Result: Ten patients (mean age: 9.7 years of lower canaliculus injury were included. Successful stenting was accomplished in all cases. Postoperative eyelid position was satisfactory in most patients. The mean postoperative follow-up period was 6 months. There were no cases of premature stent extrusion. Functional drainage after stent removal was normal in all of patients. Syringing showed full patency. Conclusion:The MiniMonoka monocanalicular stent is an effective tool in reconstructing traumatic canalicular lacerations. Easy to use, carries a minimal risk of infection and injury to the non-lacerated canaliculus, and results in high anatomical and functional success rates.

  5. ANTARES alternative event reconstruction strategies

    CERN Document Server

    Becherini, Y

    2007-01-01

    The ANTARES Collaboration is building a high-energy neutrino telescope at 2500 m depth in the Mediterranean Sea. The experiment aims to search for high-energy cosmic neutrinos through the detection of Cerenkov light induced by muons and showers resulting from neutrino interactions with the surrounding medium. The detector will consist of a three-dimensional array of 900 optical modules housing photomultipliers. It will be composed of 12 strings, 5 of them being already in operation since January 2007. The muon track is reconstructed from the arrival time and the charge of the signals obtained from the photomultipliers, whose positions are known by means of an acoustic positioning system. The reconstruction strategies include several steps among which there are: optical background filtering, algorithms for first estimations of the track parameters, and a final fit aiming to reach an angular resolution better than 0.3 degree above 10 TeV in the full detector. Different reconstruction strategies will be presente...

  6. Femoral Reconstruction Using External Fixation

    Directory of Open Access Journals (Sweden)

    Yevgeniy Palatnik

    2011-01-01

    Full Text Available Background. The use of an external fixator for the purpose of distraction osteogenesis has been applied to a wide range of orthopedic problems caused by such diverse etiologies as congenital disease, metabolic conditions, infections, traumatic injuries, and congenital short stature. The purpose of this study was to analyze our experience of utilizing this method in patients undergoing a variety of orthopedic procedures of the femur. Methods. We retrospectively reviewed our experience of using external fixation for femoral reconstruction. Three subgroups were defined based on the primary reconstruction goal lengthening, deformity correction, and repair of nonunion/bone defect. Factors such as leg length discrepancy (LLD, limb alignment, and external fixation time and complications were evaluated for the entire group and the 3 subgroups. Results. There was substantial improvement in the overall LLD, femoral length discrepancy, and limb alignment as measured by mechanical axis deviation (MAD and lateral distal femoral angle (LDFA for the entire group as well as the subgroups. Conclusions. The Ilizarov external fixator allows for decreased surgical exposure and preservation of blood supply to bone, avoidance of bone grafting and internal fixation, and simultaneous lengthening and deformity correction, making it a very useful technique for femoral reconstruction.

  7. Reduction of reconstruction time for time-resolved spiral 3D contrast-enhanced magnetic resonance angiography using parallel computing.

    Science.gov (United States)

    Kressler, Bryan; Spincemaille, Pascal; Prince, Martin R; Wang, Yi

    2006-09-01

    Time-resolved 3D MRI with high spatial and temporal resolution can be achieved using spiral sampling and sliding-window reconstruction. Image reconstruction is computationally intensive because of the need for data regridding, a large number of temporal phases, and multiple RF receiver coils. Inhomogeneity blurring correction for spiral sampling further increases the computational work load by an order of magnitude, hindering the clinical utility of spiral trajectories. In this work the reconstruction time is reduced by a factor of >40 compared to reconstruction using a single processor. This is achieved by using a cluster of 32 commercial off-the-shelf computers, commodity networking hardware, and readily available software. The reconstruction system is demonstrated for time-resolved spiral contrast-enhanced (CE) peripheral MR angiography (MRA), and a reduction of reconstruction time from 80 min to 1.8 min is achieved. PMID:16892189

  8. Tomographic reconstruction of high energy density plasmas with picosecond temporal resolution

    Energy Technology Data Exchange (ETDEWEB)

    Baker, K L

    2005-09-20

    Three-dimensional reconstruction of the electron density in a plasma can be obtained by passing multiple beams at different field angles simultaneously through a plasma and performing a tomographic reconstruction of the measured field-dependent phase profiles. In this letter, a relatively simple experimental setup is proposed and simulations are carried out to verify the technique. The plasma distribution is modeled as a discreet number of phase screens and a Zernike polynomial representation of the phase screens is used to reconstruct the plasma profile. Using a subpicosecond laser, the complete three-dimensional electron density of the plasma can be obtained with a time resolution limited only by the transit time of the probe through the plasma.

  9. Reconciling reconstructed and simulated features of the winter Pacific–North-American pattern in the early 19th century

    Directory of Open Access Journals (Sweden)

    D. Zanchettin

    2014-11-01

    Full Text Available Reconstructions of past climate behavior often describe prominent anomalous periods that are not necessarily captured in climate simulations. Here, we illustrate the contrast between an interdecadal strong positive phase of the winter Pacific/North American pattern (PNA in the early 19th century that is described by a PNA reconstruction based on tree-rings from northwestern North America, and a slight tendency towards negative winter PNA anomalies during the same period in an ensemble of state-of-the-art coupled climate simulations. Additionally, a pseudo-proxy investigation with the same simulation ensemble allows assessing the robustness of PNA reconstructions using solely geophysical predictors from northwestern North America for the last millennium. The reconstructed early-19th-century positive PNA anomaly emerges as a potentially reliable feature, although it is subject to a number of sources of uncertainty and potential deficiencies. The pseudo-reconstructions demonstrate that the early-19th-century discrepancy between reconstructed and simulated PNA does not stem from the reconstruction process. Instead, reconstructed and simulated features of the early-19th-century PNA can be reconciled by interpreting the reconstructed evolution during this time as an expression of internal climate variability, hence unlikely to be reproduced in its exact temporal occurrence by a small ensemble of climate simulations. However, firm attribution of the reconstructed PNA anomaly is hampered by known limitations and deficiencies of coupled climate models and uncertainties in the early-19th-century external forcing and background climate conditions.

  10. Robustness of nuclear core activity reconstruction by data assimilation

    International Nuclear Information System (INIS)

    The purpose of data assimilation methods is to merge measurements and information coming from a numerical model, in order to obtain an optimal estimation of the field of physical quantities of interest. We apply data assimilation techniques to perform an optimal reconstruction of the neutronic activity field in a nuclear core. This study is based on the standard 900 MWe PWR core, the measurement data come from the mobile fission chambers distributed in the fuel assemblies and the simulation code used is COCAGNE. One of the main advantages of data assimilation is that it takes into account every kind of heterogeneous information within the same framework. Moreover, this method has a formalism that allows adapting itself to instrument configuration changes. We exploit this last property here, to study the quality of the reconstructed activity field as a function of the number of available measurements. it was shown that the slope of the reconstruction quality is mainly governed by the distribution of the instruments. Depending on the chosen distribution, the decrease consists in two or three distinct phases. The ultimate stagnation phase in this decreasing is governed by both statistical effect and heterogeneity of instrument influence

  11. STUDY ON PHASE PERCEPTION IN SPEECH

    Institute of Scientific and Technical Information of China (English)

    Tong Ming; Bian Zhengzhong; Li Xiaohui; Dai Qijun; Chen Yanpu

    2003-01-01

    The perceptual effect of the phase information in speech has been studied by auditorysubjective tests. On the condition that the phase spectrum in speech is changed while amplitudespectrum is unchanged, the tests show that: (1) If the envelop of the reconstructed speech signalis unchanged, there is indistinctive auditory perception between the original speech and thereconstructed speech; (2) The auditory perception effect of the reconstructed speech mainly lieson the amplitude of the derivative of the additive phase; (3) td is the maximum relative time shiftbetween different frequency components of the reconstructed speech signal. The speech qualityis excellent while td <10ms; good while 10ms< td <20ms; common while 20ms< td <35ms, andpoor while td >35ms.

  12. Reconstruction of spectral solar irradiance since 1700 from simulated magnetograms

    CERN Document Server

    Dasi-Espuig, M; Krivova, N A; Solanki, S K; Unruh, Y C; Yeo, K L

    2016-01-01

    We present a reconstruction of the spectral solar irradiance since 1700 using the SATIRE-T2 (Spectral And Total Irradiance REconstructions for the Telescope era version 2) model. This model uses as input magnetograms simulated with a surface flux transport model fed with semi-synthetic records of emerging sunspot groups. We used statistical relationships between the properties of sunspot group emergence, such as the latitude, area, and tilt angle, and the sunspot cycle strength and phase to produce semi-synthetic sunspot group records starting in the year 1700. The semisynthetic records are fed into a surface flux transport model to obtain daily simulated magnetograms that map the distribution of the magnetic flux in active regions (sunspots and faculae) and their decay products on the solar surface. The magnetic flux emerging in ephemeral regions is accounted for separately based on the concept of extended cycles whose length and amplitude are linked to those of the sunspot cycles through the sunspot number....

  13. Phase microscopy of technical and biological samples through random phase modulation with a difuser

    DEFF Research Database (Denmark)

    Almoro, Percival; Pedrini, Giancarlo; Gundu, Phanindra Narayan; Osten, Wolfgang; Hanson, Steen Grüner

    2010-01-01

    A technique for phase microscopy using a phase diffuser and a reconstruction algorithm is proposed. A magnified specimen wavefront is projected on the diffuser plane that modulates the wavefront into a speckle field. The speckle patterns at axially displaced planes are sampled and used in an iter...

  14. Reduction of motion artifacts in cardiac CT based on partial angle reconstructions from short scan data

    Science.gov (United States)

    Hahn, Juliane; Bruder, Herbert; Allmendinger, Thomas; Stierstorfer, Karl; Flohr, Thomas; Kachelriess, Marc

    2016-03-01

    Until today, several software-based approaches to increase the temporal resolution in cardiac computed tomography by estimating motion vector fields (MVFs) have been developed. Thereunder, the majority are motion compensation algorithms, which estimate the MVFs employing a three-dimensional registration routine working on reconstructions of multiple cardiac phases.2, 6, 7, 12 We present an algorithm that requires nothing more than the data needed for a short scan reconstruction for motion estimation and motion-compensated reconstruction, which both are based on the reconstruction of volumes from a limited angular range.2, 3, 7, 8 Those partial angle reconstructions are centered at different time points during the short scan and have a temporal resolution of about 10ms each. The MVFs are estimated by a constrained cost function optimization routine employing a motion artifact measuring cost function. During optimization, the MVFs are applied directly by warping the partial angle reconstructions, and the motion compensation is established by simply adding the shifted images. In order to enforce smooth vector fields and keep the number of parameters low, the motion is modeled by a low degree polynomial. Furthermore, to find a good estimation of the MVFs even in phases with rapid cardiac motion, the constrained optimization is re-initialized multiple times. The algorithm is validated with the help of a simulation study and applied to patient data, where motion- compensated reconstructions are performed in various cardiac phases. We show that the image quality can be improved, also in more rapid cardiac phases due to re-initialization of the optimization routine.

  15. Simultaneous motion estimation and image reconstruction (SMEIR) for 4D cone-beam CT

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jing; Gu, Xuejun [Department of Radiation Oncology, The University of Texas Southwestern Medical Center, Dallas, Texas 75235-8808 (United States)

    2013-10-15

    Purpose: Image reconstruction and motion model estimation in four-dimensional cone-beam CT (4D-CBCT) are conventionally handled as two sequential steps. Due to the limited number of projections at each phase, the image quality of 4D-CBCT is degraded by view aliasing artifacts, and the accuracy of subsequent motion modeling is decreased by the inferior 4D-CBCT. The objective of this work is to enhance both the image quality of 4D-CBCT and the accuracy of motion model estimation with a novel strategy enabling simultaneous motion estimation and image reconstruction (SMEIR).Methods: The proposed SMEIR algorithm consists of two alternating steps: (1) model-based iterative image reconstruction to obtain a motion-compensated primary CBCT (m-pCBCT) and (2) motion model estimation to obtain an optimal set of deformation vector fields (DVFs) between the m-pCBCT and other 4D-CBCT phases. The motion-compensated image reconstruction is based on the simultaneous algebraic reconstruction technique (SART) coupled with total variation minimization. During the forward- and backprojection of SART, measured projections from an entire set of 4D-CBCT are used for reconstruction of the m-pCBCT by utilizing the updated DVF. The DVF is estimated by matching the forward projection of the deformed m-pCBCT and measured projections of other phases of 4D-CBCT. The performance of the SMEIR algorithm is quantitatively evaluated on a 4D NCAT phantom. The quality of reconstructed 4D images and the accuracy of tumor motion trajectory are assessed by comparing with those resulting from conventional sequential 4D-CBCT reconstructions (FDK and total variation minimization) and motion estimation (demons algorithm). The performance of the SMEIR algorithm is further evaluated by reconstructing a lung cancer patient 4D-CBCT.Results: Image quality of 4D-CBCT is greatly improved by the SMEIR algorithm in both phantom and patient studies. When all projections are used to reconstruct a 3D-CBCT by FDK, motion

  16. Three-dimension reconstruction based on spatial light modulator

    Science.gov (United States)

    Deng, Xuejiao; Zhang, Nanyang; Zeng, Yanan; Yin, Shiliang; Wang, Weiyu

    2011-02-01

    Three-dimension reconstruction, known as an important research direction of computer graphics, is widely used in the related field such as industrial design and manufacture, construction, aerospace, biology and so on. Via such technology we can obtain three-dimension digital point cloud from a two-dimension image, and then simulate the three-dimensional structure of the physical object for further study. At present, the obtaining of three-dimension digital point cloud data is mainly based on the adaptive optics system with Shack-Hartmann sensor and phase-shifting digital holography. Referring to surface fitting, there are also many available methods such as iterated discrete fourier transform, convolution and image interpolation, linear phase retrieval. The main problems we came across in three-dimension reconstruction are the extraction of feature points and arithmetic of curve fitting. To solve such problems, we can, first of all, calculate the relevant surface normal vector information of each pixel in the light source coordinate system, then these vectors are to be converted to the coordinates of image through the coordinate conversion, so the expectant 3D point cloud get arise. Secondly, after the following procedures of de-noising, repairing, the feature points can later be selected and fitted to get the fitting function of the surface topography by means of Zernike polynomial, so as to reconstruct the determinand's three-dimensional topography. In this paper, a new kind of three-dimension reconstruction algorithm is proposed, with the assistance of which, the topography can be estimated from its grayscale at different sample points. Moreover, the previous stimulation and the experimental results prove that the new algorithm has a strong capability to fit, especially for large-scale objects .

  17. A methodology to event reconstruction from trace images.

    Science.gov (United States)

    Milliet, Quentin; Delémont, Olivier; Sapin, Eric; Margot, Pierre

    2015-03-01

    The widespread use of digital imaging devices for surveillance (CCTV) and entertainment (e.g., mobile phones, compact cameras) has increased the number of images recorded and opportunities to consider the images as traces or documentation of criminal activity. The forensic science literature focuses almost exclusively on technical issues and evidence assessment [1]. Earlier steps in the investigation phase have been neglected and must be considered. This article is the first comprehensive description of a methodology to event reconstruction using images. This formal methodology was conceptualised from practical experiences and applied to different contexts and case studies to test and refine it. Based on this practical analysis, we propose a systematic approach that includes a preliminary analysis followed by four main steps. These steps form a sequence for which the results from each step rely on the previous step. However, the methodology is not linear, but it is a cyclic, iterative progression for obtaining knowledge about an event. The preliminary analysis is a pre-evaluation phase, wherein potential relevance of images is assessed. In the first step, images are detected and collected as pertinent trace material; the second step involves organising and assessing their quality and informative potential. The third step includes reconstruction using clues about space, time and actions. Finally, in the fourth step, the images are evaluated and selected as evidence. These steps are described and illustrated using practical examples. The paper outlines how images elicit information about persons, objects, space, time and actions throughout the investigation process to reconstruct an event step by step. We emphasise the hypothetico-deductive reasoning framework, which demonstrates the contribution of images to generating, refining or eliminating propositions or hypotheses. This methodology provides a sound basis for extending image use as evidence and, more generally

  18. Immediate Debridement and Reconstruction with

    Directory of Open Access Journals (Sweden)

    Hyoseob Lim

    2012-01-01

    Full Text Available Background Poststernotomy mediastinitis is a rare, but life-threatening complication,thus early diagnosis and proper management is essential for poststernotomy mediastinitis.The main treatment for mediastinitis is aggressive debridement. Several options exist forreconstruction of defects after debridement. The efficacy of immediate debridement andreconstruction with a pectoralis major muscle flap designed for the defect immediately afterthe diagnosis of poststernotomy mediastinitis is demonstrated.Methods Between September 2009 and June 2011, 6 patients were referred to the Departmentof Plastic and Reconstructive Surgery and the Department of Thoracic and CardiovascularSurgery of Ajou University Hospital for poststernotomy mediastinitis. All of the patientsunderwent extensive debridement and reconstruction with pectoralis major muscle flaps,advanced based on the pedicle of the thoracoacromial artery as soon as possible followingdiagnosis. A retrospective review of the 6 cases was performed to evaluate infection control,postoperative morbidity, and mortality.Results All patients had complete wound closures and reduced severity of infections basedon the erythrocyte sedimentation rate and C-reactive protein levels and a reduction inpoststernal fluid collection on computed tomography an average of 6 days postoperatively.A lack of growth of organisms in the wound culture was demonstrated after 3 weeks. Therewere no major wound morbidities, such as hematomas, but one minor complication requireda skin graft caused by skin flap necrosis. No patient expired after definitive surgery.Conclusions Immediate debridement and reconstruction using a pectoralis major muscle flapis a safe technique for managing infections associated with poststernotomy mediastinitis,and is associated with minimal morbidity and mortality.

  19. Unsupervised learning of spect reconstruction

    International Nuclear Information System (INIS)

    An approach of image reconstruction from projection in single-photon emission computed tomography (SPECT), based on an unsupervised learning artificial Kohonen neural network, is developed. A kind of random sampling technique is used to generate sensory input from tomographic projections. It is proved that an adequate interpretation and representation of the synaptic strengths of the network can be used to obtain the tomographic image. A relevant numerical experiment is reported. To validate the method tests were performed using a typical phantom (simulated object) used in limited data sets tomography. At the end of the self-organizing process the synaptic strengths can be shown on x-y plane as a map of points. The density of points gives the reconstructed image. In order to obtain a usual representation of the image a grid of 32 x 32 pixels was superimposed on the map and the number of points in each pixel was counted in order to form the image function. As the number of points in each pixel (especially for pixels corresponding to the background of the phantom) is relatively small, the image function is spoiled by noise. Noise filtering was used to improve the quality of the image. The final result is presented as a 3D-surface plot and as a corresponding 8-level gray map. It can be concluded that a good reconstruction of sizes and shapes was obtained. Some artifacts spoil the region located around the spikes. This artifact can be reduced if an increased number of external stimuli are presented to the network. The price paid for this improvement is the increase of computation time. (authors)

  20. Hanford Environmental Dose Reconstruction Project

    International Nuclear Information System (INIS)

    The objective of the Hanford Environmental Dose Reconstruction Project is to estimate the radiation doses that populations could have received from nuclear operations at Hanford since 1944. The project is being managed and conducted by the Pacific Northwest Laboratory (PNL) under the direction of an independent Technical Steering Panel (TSP). The project is divided into the following technical tasks. These tasks correspond to the path radionuclides followed, from released to impact on humans (dose estimates): source terms; environmental transport; environmental monitoring data; demographics, agriculture, food habits; and, environmental pathways and dose estimates

  1. Perforator Flaps for Perineal Reconstructions

    OpenAIRE

    Niranjan, Niri S.

    2006-01-01

    Whenever there is soft tissue loss from the perineum there are many options for reconstruction. These include allowing the wound to heal by secondary intention and the use of local random or axial pattern flaps, regional flaps, or free flaps. The axial skin flap can be defined as a flap based on known constant vessels of the subcutaneous tissue and its vena comitantes. The perforator flap on the other hand is a randomly selected perforator consisting of an artery with vena comitantes, which p...

  2. The Arthroscopic Superior Capsular Reconstruction.

    Science.gov (United States)

    Adams, Christopher R; Denard, Patrick J; Brady, Paul C; Hartzler, Robert U; Burkhart, Stephen S

    2016-01-01

    In a subset of patients with rotator cuff tears, the glenohumeral joint has minimal degenerative changes and the rotator cuff tendon is either irreparable or very poor quality and unlikely to heal. Reverse shoulder arthroplasty (RSA) is often considered for these patients despite the lack of glenohumeral arthritis. However, due to the permanent destruction of the glenohumeral articular surfaces, complication rates, and concerns about implant longevity with RSA, we believe the superior capsular reconstruction (SCR) is a viable alternative. In this article, we describe our technique for the SCR. PMID:27552457

  3. Reconstruction of fundamental SUSY parameters

    Energy Technology Data Exchange (ETDEWEB)

    P. M. Zerwas et al.

    2003-09-25

    We summarize methods and expected accuracies in determining the basic low-energy SUSY parameters from experiments at future e{sup +}e{sup -} linear colliders in the TeV energy range, combined with results from LHC. In a second step we demonstrate how, based on this set of parameters, the fundamental supersymmetric theory can be reconstructed at high scales near the grand unification or Planck scale. These analyses have been carried out for minimal supergravity [confronted with GMSB for comparison], and for a string effective theory.

  4. Hanford Environmental Dose Reconstruction Project

    International Nuclear Information System (INIS)

    The objective of the Hanford Environmental Dose Reconstruction Project is to estimate the radiation doses that individuals and populations could have received from nuclear operations at Hanford since 1944. The project is being managed and conducted by the Battelle Pacific Northwest Laboratories under contract with the Centers for Disease Control. The independent Technical Steering Panel (TSP) provides technical direction. The project is divided into the following technical tasks. These tasks correspond to the path radionuclides followed, from release to impact on humans (dose estimates): source terms; environmental transport; environmental monitoring data; demography, food consumption, and agriculture; environmental pathways and dose estimates

  5. Economics of abdominal wall reconstruction.

    Science.gov (United States)

    Bower, Curtis; Roth, J Scott

    2013-10-01

    The economic aspects of abdominal wall reconstruction are frequently overlooked, although understandings of the financial implications are essential in providing cost-efficient health care. Ventral hernia repairs are frequently performed surgical procedures with significant economic ramifications for employers, insurers, providers, and patients because of the volume of procedures, complication rates, the significant rate of recurrence, and escalating costs. Because biological mesh materials add significant expense to the costs of treating complex abdominal wall hernias, the role of such costly materials needs to be better defined to ensure the most cost-efficient and effective treatments for ventral abdominal wall hernias. PMID:24035086

  6. Reconstruction of spectral solar irradiance since 1700 from simulated magnetograms

    Science.gov (United States)

    Dasi-Espuig, M.; Jiang, J.; Krivova, N. A.; Solanki, S. K.; Unruh, Y. C.; Yeo, K. L.

    2016-05-01

    Aims: We present a reconstruction of the spectral solar irradiance since 1700 using the SATIRE-T2 (Spectral And Total Irradiance REconstructions for the Telescope era version 2) model. This model uses as input magnetograms simulated with a surface flux transport model fed with semi-synthetic records of emerging sunspot groups. Methods: The record of sunspot group areas and positions from the Royal Greenwich Observatory (RGO) is only available since 1874. We used statistical relationships between the properties of sunspot group emergence, such as the latitude, area, and tilt angle, and the sunspot cycle strength and phase to produce semi-synthetic sunspot group records starting in the year 1700. The semi-synthetic records are fed into a surface flux transport model to obtain daily simulated magnetograms that map the distribution of the magnetic flux in active regions (sunspots and faculae) and their decay products on the solar surface. The magnetic flux emerging in ephemeral regions is accounted for separately based on the concept of extended cycles whose length and amplitude are linked to those of the sunspot cycles through the sunspot number. The magnetic flux in each surface component (sunspots, faculae and network, and ephemeral regions) was used to compute the spectral and total solar irradiance (TSI) between the years 1700 and 2009. This reconstruction is aimed at timescales of months or longer although the model returns daily values. Results: We found that SATIRE-T2, besides reproducing other relevant observations such as the total magnetic flux, reconstructs the TSI on timescales of months or longer in good agreement with the PMOD composite of observations, as well as with the reconstruction starting in 1878 based on the RGO-SOON data. The model predicts an increase in the TSI of 1.2+0.2-0.3 Wm-2 between 1700 and the present. The spectral irradiance reconstruction is in good agreement with the UARS/SUSIM measurements as well as the Lyman-α composite. The

  7. Suppression of zero order diffraction from the reconstructed images in digital holography

    Directory of Open Access Journals (Sweden)

    M R Rashidian Vaziri

    2016-02-01

    Full Text Available The numerically reconstructed images in digital holography contain two undesirable features. After reconstruction, the zero order diffraction as well as the complex conjugate image will be present in pictures and drastically reduce their qualities. Practical applications of digital holography in the context of characterization and measuring the physical properties of objects require the suppression of these two features, before starting the reconstruction phase. In this work, using the required mathematical functions for suppressing the zero order diffraction and by transforming them to their discrete form, numerical filters for passing over the CCD images have been constructed. After passing these filters over the experimentally recorded CCD images, the reconstruction phase has been completed applying the discrete Fresnel transform. Carefully investigating the quality of various reconstructed images, we came to the conclusion that if a filter covers a smaller neighborhood of the recorded CCD images, it will have a better performance in suppressing the zero order diffraction. Among the used filters in this work, a 3×3 average filter showed the best performance in suppressing the zero order diffraction from the reconstructed images.

  8. Surface reconstructions and transport of epitaxial PtLuSb (001) thin films grown by MBE

    Science.gov (United States)

    Patel, Sahil J.; Logan, John A.; Harrington, Sean D.; Schultz, Brian D.; Palmstrøm, Chris J.

    2016-02-01

    This work presents the surface reconstructions and transport properties of the topological insulator PtLuSb grown on Al0.1In0.9Sb/GaAs (001). Two stable surface reconstructions, (1×3) and c(2×2), were observed on PtLuSb (001) surfaces. Antimony-dimerization was determined to be the nature of the (1×3) surface reconstruction as evidenced by chemical binding energy shifts in the antimony 4d core-level for surface bonding components. The two surface reconstructions were studied as a function of Sb4 overpressure and substrate temperature to create a reconstruction phase diagram. From this reconstruction phase diagram, a growth window from 320 °C to 380 °C using an antimony overpressure was identified. Within this window, the highest quality films were grown at a growth temperature of 380 °C. These films exhibited lower p-type carrier concentrations as well as relatively high hole mobilities.

  9. Modification of the reconstruction distance of Fresnel holograms for display with multiple spatial light modulators

    Science.gov (United States)

    Leportier, Thibault; Park, Min-Chul; Kim, Taegeun

    2016-06-01

    In digital holography, spatial light modulators (SLMs) devices are used to display the holographic patterns. However, modulation is imperfect because SLMs cannot modulate phase and amplitude at the same time. Then undesired terms such as twin image can be observed in the image plane. One solution to remove twin image contribution without physical spatial filter is to perform complex modulation. Phase and amplitude modulation can be performed sequentially with two different SLMs. Similarly, real and imaginary part of hologram can be displayed and combined in an additive configuration through a polarizing beam splitter. In both case, a major problem is the alignment of the two display devices since misalignment as small as one pixel may degrade significantly quality of the reconstruction. For our experiment, we used data computed numerically to obtain separately real and imaginary part of hologram. Then, we focused on additive configuration where two SLMs are displaying real and imaginary part of hologram respectively. Reconstruction distance of hologram is fixed and distance between SLM and beam splitter should be the same for the two devices. In this paper, we study the effect of having different reconstruction distance for the real and imaginary hologram. We performed simulations and explained the result with the scalar diffraction theory. A method to compensate numerically the reconstruction distance is proposed for on-axis configuration. This method can also be applied to modify reconstruction distance of Fresnel hologram displayed with a single SLM and has potential application in RGB holographic reconstruction

  10. Practical methods for automated reconstruction and characterization of particles in digital in-line holograms

    International Nuclear Information System (INIS)

    Hologram reconstruction algorithms often undersample the phase in propagation kernels for typical parameters of holographic optical setups. Given in this paper is an algorithm that addresses this phase undersampling in reconstructing digital in-line holograms of particles for these typical parameters. This algorithm has a lateral sample spacing constant in reconstruction distance, has a diffraction limited resolution, and can be implemented with computational speeds comparable to the fastest of other reconstruction algorithms. This algorithm is shown to be accurate by testing with analytical solutions to the Huygens–Fresnel propagation integral. A low-pass filter can be applied to enforce a uniform minimum particle size detection limit throughout a sample volume, allowing this method to be useful in measuring particle size distributions and number densities. Tens of thousands of holograms of cloud ice particles are digitally reconstructed using the algorithm discussed. Positions of ice particles in the size range of 20 µm–1.5 mm are obtained using an algorithm that accurately finds the position of large and small particles along the optical axis. The digital reconstruction and particle characterization algorithms are implemented in an automated fashion with no user intervention on a computer cluster. Strategies for efficient algorithm implementation on a computer cluster are discussed

  11. Practical methods for automated reconstruction and characterization of particles in digital in-line holograms

    Science.gov (United States)

    Fugal, Jacob P.; Schulz, Timothy J.; Shaw, Raymond A.

    2009-07-01

    Hologram reconstruction algorithms often undersample the phase in propagation kernels for typical parameters of holographic optical setups. Given in this paper is an algorithm that addresses this phase undersampling in reconstructing digital in-line holograms of particles for these typical parameters. This algorithm has a lateral sample spacing constant in reconstruction distance, has a diffraction limited resolution, and can be implemented with computational speeds comparable to the fastest of other reconstruction algorithms. This algorithm is shown to be accurate by testing with analytical solutions to the Huygens-Fresnel propagation integral. A low-pass filter can be applied to enforce a uniform minimum particle size detection limit throughout a sample volume, allowing this method to be useful in measuring particle size distributions and number densities. Tens of thousands of holograms of cloud ice particles are digitally reconstructed using the algorithm discussed. Positions of ice particles in the size range of 20 µm-1.5 mm are obtained using an algorithm that accurately finds the position of large and small particles along the optical axis. The digital reconstruction and particle characterization algorithms are implemented in an automated fashion with no user intervention on a computer cluster. Strategies for efficient algorithm implementation on a computer cluster are discussed.

  12. A Motion Detection Algorithm Using Local Phase Information

    OpenAIRE

    Lazar, Aurel A; Ukani, Nikul H.; Yiyin Zhou

    2016-01-01

    Previous research demonstrated that global phase alone can be used to faithfully represent visual scenes. Here we provide a reconstruction algorithm by using only local phase information. We also demonstrate that local phase alone can be effectively used to detect local motion. The local phase-based motion detector is akin to models employed to detect motion in biological vision, for example, the Reichardt detector. The local phase-based motion detection algorithm introduced here consists of ...

  13. Differentiation method for phase recovery

    Science.gov (United States)

    Özcan, Meriç

    2015-03-01

    Here we consider a derivative based method for phase recovery and demonstrate a numerical method that can be described as differentiate and cross multiply operation to obtain the phase gradient. This method uses quadrature phase data that is in sine and cosine form, which is a natural outcome many interferometric measurements including that of digital holographic reconstruction. Since the differentiation is performed on trigonometric functions which are discrete, it is shown that the method of differentiation and the sampling rate are important considerations especially for the noise corrupt signals. The method is initially developed for 1D phase signals, and then later extended to 2D. Noise performance of the method is also investigated, and it is shown that for extremely noisy signals the method can be adapted to an iteration routine which recovers the phase successfully. We present simulations and the experimental results which show the validity of the approach.

  14. Improvement of the image quality of random phase--free holography using an iterative method

    CERN Document Server

    Shimobaba, Tomoyoshi; Endo, Yutaka; Hirayama, Ryuji; Hiyama, Daisuke; Hasegawa, Satoki; Nagahama, Yuki; Sano, Marie; Oikawa, Minoru; Sugie, Takashige; Ito, Tomoyoshi

    2015-01-01

    Our proposed method of random phase-free holography using virtual convergence light can obtain large reconstructed images exceeding the size of the hologram, without the assistance of random phase. The reconstructed images have low-speckle noise in the amplitude and phase-only holograms (kinoforms); however, in low-resolution holograms, we obtain a degraded image quality compared to the original image. We propose an iterative random phase-free method with virtual convergence light to address this problem.

  15. Tomographic phase microscopy using optical tweezers

    Science.gov (United States)

    Habaza, Mor; Gilboa, Barak; Roichman, Yael; Shaked, Natan T.

    2015-07-01

    We review our technique for tomographic phase microscopy with optical tweezers [1]. This tomographic phase microscopy approach enables full 3-D refractive-index reconstruction. Tomographic phase microscopy measures quantitatively the 3- D distribution of refractive-index in biological cells. We integrated our external interferometric module with holographic optical tweezers for obtaining quantitative phase maps of biological samples from a wide range of angles. The close-tocommon- path, off-axis interferometric system enables a full-rotation tomographic acquisition of a single cell using holographic optical tweezers for trapping and manipulating with a desired array of traps, while acquiring phase information of a single cell from all different angles and maintaining the native surrounding medium. We experimentally demonstrated two reconstruction algorithms: the filtered back-projection method and the Fourier diffraction method for 3-D refractive index imaging of yeast cells.

  16. Sequence-Length Requirement of Distance-Based Phylogeny Reconstruction: Breaking the Polynomial Barrier

    CERN Document Server

    Roch, Sebastien

    2009-01-01

    We introduce a new distance-based phylogeny reconstruction technique which provably achieves, at sufficiently short branch lengths, a polylogarithmic sequence-length requirement -- improving significantly over previous polynomial bounds for distance-based methods. The technique is based on an averaging procedure that implicitly reconstructs ancestral sequences. In the same token, we extend previous results on phase transitions in phylogeny reconstruction to general time-reversible models. More precisely, we show that in the so-called Kesten-Stigum zone (roughly, a region of the parameter space where ancestral sequences are well approximated by ``linear combinations'' of the observed sequences) sequences of length $\\poly(\\log n)$ suffice for reconstruction when branch lengths are discretized. Here $n$ is the number of extant species. Our results challenge, to some extent, the conventional wisdom that estimates of evolutionary distances alone carry significantly less information about phylogenies than full sequ...

  17. NOISE AMPLIFICATION ANALYSIS AND COMPARISON OF TWO PERIODIC NONUNIFORM SAMPLING RECONSTRUCTION METHODS USED IN DPCA SAR

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    General Sampling Expansion Reconstruction Method(GSERM)and Digital Spectrum Reconstruction Method(DSRM),which prove effective to reconstruct azimuth signal of Displaced Phase Center Apertures(DPCA) Synthetic Aperture areal"(SAR)system from its Periodic Non-Uniform Sampling(PNUS)data sequences,would amplify the noise and sidelobe clutter simultaneously in the reconstruction.This paper formulates the relation of the system transfer matrixes of the above two methods,gives the properties,such aS periodicity,symmetry,and time-shift property,of their Noise and Sidelobe Clutter Amplification Factor(NSCAF),and discovers that DSRM is more sensitive than GSERM in the white noise environment.In addition,criteria based on initial sampling point analysis for the robust PRF selection are suggested.Computer simulation results support these con-clusions.

  18. Bayes reconstruction of missing teeth

    DEFF Research Database (Denmark)

    Sporring, Jon; Jensen, Katrine Hommelhoff

    2008-01-01

     We propose a method for restoring the surface of tooth crowns in a 3D model of a human denture, so that the pose and anatomical features of the tooth will work well for chewing. This is achieved by including information about the position and anatomy of the other teeth in the mouth. Our system...... contains two major parts: A statistical model of a selection of tooth shapes and a reconstruction of missing data. We use a training set consisting of 3D scans of dental cast models obtained with a laser scanner, and we have build a model of the shape variability of the teeth, their neighbors, and their...... regularization of the log-likelihood estimate based on differential geometrical properties of teeth surfaces, and we show general conditions under which this may be considered a Bayes prior.Finally we use Bayes method to propose the reconstruction of missing data, for e.g. finding the most probable shape of a...

  19. [Phoniatric aspects of reconstructive laryngectomy].

    Science.gov (United States)

    Genovese, E; Calearo, C; Bignardi, I

    1992-01-01

    Reconstructive laryngectomy has been performed at the E.N.T. Clinic in Ferrara for some time. After surgery the patients undergo speech therapy and phoniatric treatment for a period of time varying from 2 to 6 months. In order to better evaluate the vocal quality obtained after such reeducation the vocal emissions of 25 patients were examined and recorded. The recorded material, made up of prolonged vowels and 6 phonetically balanced sentences, was then evaluated by a panel of 7 "trained" listeners. The evaluation score-card proposed by Woiers in 1977 was used in taking the data. This not only provides a scale for evaluating the main voice quality features, but also includes a final judgement on parameters including intelligibility, acceptability and pleasantness. Statistical processing of the data inherent to voice quality indicated a decrease in intensity and pitch when compared to normal values. Nonetheless, the listening test showed a high degree of intelligibility, acceptability and pleasantness. These values confirm the fact that, although the new voice achieved through reconstructive laryngectomy surgery is less sonorous, it allows for perfectly understandable, socially acceptable speech. PMID:1344550

  20. Stereo reconstruction from multiperspective panoramas.

    Science.gov (United States)

    Li, Yin; Shum, Heung-Yeung; Tang, Chi-Keung; Szeliski, Richard

    2004-01-01

    A new approach to computing a panoramic (360 degrees) depth map is presented in this paper. Our approach uses a large collection of images taken by a camera whose motion has been constrained to planar concentric circles. We resample regular perspective images to produce a set of multiperspective panoramas and then compute depth maps directly from these resampled panoramas. Our panoramas sample uniformly in three dimensions: rotation angle, inverse radial distance, and vertical elevation. The use of multiperspective panoramas eliminates the limited overlap present in the original input images and, thus, problems as in conventional multibaseline stereo can be avoided. Our approach differs from stereo matching of single-perspective panoramic images taken from different locations, where the epipolar constraints are sine curves. For our multiperspective panoramas, the epipolar geometry, to the first order approximation, consists of horizontal lines. Therefore, any traditional stereo algorithm can be applied to multiperspective panoramas with little modification. In this paper, we describe two reconstruction algorithms. The first is a cylinder sweep algorithm that uses a small number of resampled multiperspective panoramas to obtain dense 3D reconstruction. The second algorithm, in contrast, uses a large number of multiperspective panoramas and takes advantage of the approximate horizontal epipolar geometry inherent in multiperspective panoramas. It comprises a novel and efficient 1D multibaseline matching technique, followed by tensor voting to extract the depth surface. Experiments show that our algorithms are capable of producing comparable high quality depth maps which can be used for applications such as view interpolation. PMID:15382685

  1. Reconstruction of middle ear malformations

    Directory of Open Access Journals (Sweden)

    Schwager, Konrad

    2007-01-01

    Full Text Available Malformations of the middle ear are classified as minor and major malformations. Minor malformations appear with regular external auditory canal, tympanic membrane and aerated middle ear space. The conducting hearing loss is due to fixation or interruption of the ossicular chain. The treatment is surgical, following the rules of ossiculoplasty and stapes surgery. In major malformations (congenital aural atresia there is no external auditory canal and a deformed or missing pinna. The mastoid and the middle ear space may be underdevelopped, the ossicular chain is dysplastic. Surgical therapy is possible in patients with good aeration of the temporal bone, existing windows, a near normal positioned facial nerve and a mobile ossicular chain. Plastic and reconstructive surgery of the pinna should proceed the reconstruction of the external auditory canal and middle ear. In cases of good prognosis unilateral aural atresia can be approached already in childhood. In patients with high risk of surgical failure, bone anchored hearing aids are the treatment of choice. Recent reports of implantable hearing devices may be discussed as an alternative treatment for selected patients.

  2. Irradiation autogenous mandibular grafts in primary reconstructions

    International Nuclear Information System (INIS)

    The procedure, irradiated mandibular autografts, for primary reconstruction, is presented with an immediate success rate of 88%. Eight cases have undergone primary mandibular reconstruction with the tumorous mandible irradiated to 10,000 rads in a single dose. The longest follow-up is 2 3/4 years. The autograft has proven to be an ideal implant. Major resections of the mandible in conjunction with large myocutaneous flaps have been reconstructed utilizing this implant

  3. Irradiation autogenous mandibular grafts in primary reconstructions

    Energy Technology Data Exchange (ETDEWEB)

    Hamaker, R.C.

    1981-07-01

    The procedure, irradiated mandibular autografts, for primary reconstruction, is presented with an immediate success rate of 88%. Eight cases have undergone primary mandibular reconstruction with the tumorous mandible irradiated to 10,000 rads in a single dose. The longest follow-up is 2 3/4 years. The autograft has proven to be an ideal implant. Major resections of the mandible in conjunction with large myocutaneous flaps have been reconstructed utilizing this implant.

  4. Left ventricle's surface reconstruction and volume estimation

    OpenAIRE

    Garcia-Panyella, O.; Susín Sánchez, Antonio

    2002-01-01

    This document describes the three-dimensional reconstruction of the internal and external surfaces of the human’s left ventricle from actual SPECT data. The reconstruction is a first process fitting in a complete VR application that will serve as an important diagnosis tool for hospitals. Beginning with the surfaces reconstruction, the application will provide volume and interactive real-time manipulation to the model. We focus on speed, precision and smoothness for the final surfaces. As lon...

  5. Microstructure analysis of reconstructed porous media

    OpenAIRE

    Biswal, B.; Hilfer, R.

    1999-01-01

    We compare the quantitative microstructural properties of Berea Sandstone with stochastic reconstructions of the same sandstone. The comparison is based on local porosity theory. The reconstructions employ Fourier space filtering of Gaussian random fields and match the average porosity and two-point correlation function of the experimental model. Connectivity properties of the stochastic models differ significantly from the experimental model. Reconstruction models with different levels of co...

  6. Algorithms for reconstructing images for industrial applications

    International Nuclear Information System (INIS)

    Several algorithms for reconstructing objects from their projections are being studied in our Laboratory, for industrial applications. Such algorithms are useful locating the position and shape of different composition of materials in the object. A Comparative study of two algorithms is made. The two investigated algorithsm are: The MART (Multiplicative - Algebraic Reconstruction Technique) and the Convolution Method. The comparison are carried out from the point view of the quality of the image reconstructed, number of views and cost. (Author)

  7. Underwater Image Reconstruction Using Image Fusion Technique.

    OpenAIRE

    Ms. Kulkarni Aparna S.

    2013-01-01

    In proposed work the image fusion technique is used for reconstruction of underwater image. The main purpose of proposed work is to improve resolution of underwater image. There are various method employed for reconstruction of underwater images but some have limitations such as low resolution. Resolution is one of the parameter which is important for quality of images. Wavelet based image reconstruction may improve resolution of underwater images. Image fusion technique has three levels 1) d...

  8. The Theory of Variances in Equilibrium Reconstruction

    Energy Technology Data Exchange (ETDEWEB)

    Zakharov, Leonid E.; Lewandowski, Jerome; Foley, Elizabeth L.; Levinton, Fred M.; Yuh, Howard Y.; Drozdov, Vladimir; McDonald, Darren

    2008-01-14

    The theory of variances of equilibrium reconstruction is presented. It complements existing practices with information regarding what kind of plasma profiles can be reconstructed, how accurately, and what remains beyond the abilities of diagnostic systems. The σ-curves, introduced by the present theory, give a quantitative assessment of quality of effectiveness of diagnostic systems in constraining equilibrium reconstructions. The theory also suggests a method for aligning the accuracy of measurements of different physical nature.

  9. The Theory of Variances in Equilibrium Reconstruction

    International Nuclear Information System (INIS)

    The theory of variances of equilibrium reconstruction is presented. It complements existing practices with information regarding what kind of plasma profiles can be reconstructed, how accurately, and what remains beyond the abilities of diagnostic systems. The σ-curves, introduced by the present theory, give a quantitative assessment of quality of effectiveness of diagnostic systems in constraining equilibrium reconstructions. The theory also suggests a method for aligning the accuracy of measurements of different physical nature

  10. Reconstruction of convex bodies from surface tensors

    DEFF Research Database (Denmark)

    Kousholt, Astrid; Kiderlen, Markus

    We present two algorithms for reconstruction of the shape of convex bodies in the two-dimensional Euclidean space. The first reconstruction algorithm requires knowledge of the exact surface tensors of a convex body up to rank s for some natural number s. The second algorithm uses harmonic intrinsic...... volumes which are certain values of the surface tensors and allows for noisy measurements. From a generalized version of Wirtinger's inequality, we derive stability results that are utilized to ensure consistency of both reconstruction procedures. Consistency of the reconstruction procedure based on...

  11. Uncertainty estimation in reconstructed deformable models

    Energy Technology Data Exchange (ETDEWEB)

    Hanson, K.M.; Cunningham, G.S.; McKee, R.

    1996-12-31

    One of the hallmarks of the Bayesian approach to modeling is the posterior probability, which summarizes all uncertainties regarding the analysis. Using a Markov Chain Monte Carlo (MCMC) technique, it is possible to generate a sequence of objects that represent random samples drawn from the posterior distribution. We demonstrate this technique for reconstructions of two-dimensional objects from noisy projections taken from two directions. The reconstructed object is modeled in terms of a deformable geometrically-defined boundary with a constant interior density yielding a nonlinear reconstruction problem. We show how an MCMC sequence can be used to estimate uncertainties in the location of the edge of the reconstructed object.

  12. Milestones in the History of Ear Reconstruction.

    Science.gov (United States)

    Berghaus, Alexander; Nicoló, Marion San

    2015-12-01

    The reconstruction of ear deformities has been challenging plastic surgeons since centuries. However, it is only in the 19th century that reports on partial and total ear reconstruction start increasing. In the quest for an aesthetically pleasing and natural-looking result, surgeons worked on the perfect framework and skin coverage. Different materials and flap techniques have evolved. Some were abandoned out of frustration, while others kept evolving over the years. In this article, we discuss the milestones in ear reconstruction-from ancient times to early attempts in Western civilization to the key chapters of ear reconstruction in the 20th century leading to the current techniques. PMID:26667630

  13. Dynamic reconstruction for atom probe tomography

    Energy Technology Data Exchange (ETDEWEB)

    Gault, Baptiste, E-mail: baptiste.gault@sydney.edu.au [Australian Centre for Microscopy and Microanalysis, Madsen Building F09, The University of Sydney, NSW 2006 (Australia); Institute of Materials and Engineering Science, Australian Nuclear Science and Technology Organisation, Private Mail Bag 1, Menai, NSW 2234 (Australia); Loi, Shyeh Tjing; Araullo-Peters, Vicente J.; Stephenson, Leigh T.; Moody, Michael P.; Shrestha, Sachin L.; Marceau, Ross K.W.; Yao, Lan; Cairney, Julie M.; Ringer, Simon P. [Australian Centre for Microscopy and Microanalysis, Madsen Building F09, The University of Sydney, NSW 2006 (Australia)

    2011-11-15

    Progress in the reconstruction for atom probe tomography has been limited since the first implementation of the protocol proposed by Bas et al. in 1995. This approach and those subsequently developed assume that the geometric parameters used to build the three-dimensional atom map are constant over the course of an analysis. Here, we test this assumption within the analyses of low-alloyed materials. By building upon methods recently proposed to measure the tomographic reconstruction parameters, we demonstrate that this assumption can introduce significant limitations in the accuracy of the analysis. Moreover, we propose a strategy to alleviate this problem through the implementation of a new reconstruction algorithm that dynamically accommodates variations in the tomographic reconstruction parameters. -- Highlights: Black-Right-Pointing-Pointer Variation of main reconstruction parameters, namely image compression and field factors, quantified. Black-Right-Pointing-Pointer A new protocol to build the tomographic reconstruction is proposed where reconstruction parameters are dynamically adjusted. Black-Right-Pointing-Pointer Integrity of reconstructions obtained from the standard and dynamic reconstruction protocols compared.

  14. Novel iterative reconstruction method for optimal dose usage in redundant CT - acquisitions

    Science.gov (United States)

    Bruder, H.; Raupach, R.; Allmendinger, T.; Kappler, S.; Sunnegardh, J.; Stierstorfer, K.; Flohr, T.

    2014-03-01

    In CT imaging, a variety of applications exist where reconstructions are SNR and/or resolution limited. However, if the measured data provide redundant information, composite image data with high SNR can be computed. Generally, these composite image volumes will compromise spectral information and/or spatial resolution and/or temporal resolution. This brings us to the idea of transferring the high SNR of the composite image data to low SNR (but high resolution) `source' image data. It was shown that the SNR of CT image data can be improved using iterative reconstruction [1] .We present a novel iterative reconstruction method enabling optimal dose usage of redundant CT measurements of the same body region. The generalized update equation is formulated in image space without further referring to raw data after initial reconstruction of source and composite image data. The update equation consists of a linear combination of the previous update, a correction term constrained by the source data, and a regularization prior initialized by the composite data. The efficiency of the method is demonstrated for different applications: (i) Spectral imaging: we have analysed material decomposition data from dual energy data of our photon counting prototype scanner: the material images can be significantly improved transferring the good noise statistics of the 20 keV threshold image data to each of the material images. (ii) Multi-phase liver imaging: Reconstructions of multi-phase liver data can be optimized by utilizing the noise statistics of combined data from all measured phases (iii) Helical reconstruction with optimized temporal resolution: splitting up reconstruction of redundant helical acquisition data into a short scan reconstruction with Tam window optimizes the temporal resolution The reconstruction of full helical data is then used to optimize the SNR. (iv) Cardiac imaging: the optimal phase image (`best phase') can be improved by transferring all applied over

  15. Polychromatic cone-beam phase-contrast tomography

    International Nuclear Information System (INIS)

    A method is presented for quantitative phase-contrast tomography using unfiltered radiation from a small polychromatic source. The three-dimensional distribution of complex refractive index in a monomorphous object is reconstructed given a single projection image per view angle. The reconstruction algorithm is achromatic and stable with respect to high-spatial-frequency noise, in contrast to conventional tomography. The density distribution in a test sample was accurately reconstructed from polychromatic phase-contrast data collected with a point-projection x-ray microscope

  16. Au(111) and Pt(111) surface phase behavior

    DEFF Research Database (Denmark)

    Sandy, A.R.; Mochrie, S.G.J.; Zehner, D.M.;

    1993-01-01

    We describe our recent X-ray scattering studies of the structure and phases of the clean Au(111) and Pt(111) surfaces. Below 0.65 of their respective bulk melting temperatures, the Au(111) surface has a well-ordered chevron reconstruction and the Pt(111) surface is unreconstructed. Above these...... temperatures, both surfaces reconstruct to form layers that are isotropically compresses and have only short-range order. Throughout their reconstructed phases, the densities of the Au and Pt(111) surfaces increase with increasing temperature....

  17. Moon Phases

    Science.gov (United States)

    Riddle, Bob

    2010-01-01

    When teaching Moon phases, the focus seems to be on the sequence of Moon phases and, in some grade levels, how Moon phases occur. Either focus can sometimes be a challenge, especially without the use of models and observations of the Moon. In this month's column, the author describes some of the lessons that he uses to teach the phases of the Moon…

  18. Operative Treatment of Clavicle Midshaft Fractures: Comparison between Reconstruction Plate and Reconstruction Locking Compression Plate

    OpenAIRE

    Cho, Chul-Hyun; Song, Kwang-Soon; Min, Byung-Woo; Bae, Ki-Cheor; Lee, Kyung-Jae

    2010-01-01

    Background To compare the outcomes of reconstruction plate and reconstruction locking compression plate (LCP) for the treatment of clavicle midshaft fractures. Methods Forty one patients with a clavicle midshaft fracture were treated by internal fixation with a reconstruction plate (19 patients) or reconstruction LCP (22 patients). The clinical and radiological results were evaluated according to the Quick Disability of the Arm, Shoulder, and Hand (DASH) score and plain radiographs. Results T...

  19. Respiratory motion sampling in 4DCT reconstruction for radiotherapy

    International Nuclear Information System (INIS)

    Purpose: Phase-based and amplitude-based sorting techniques are commonly used in four-dimensional CT (4DCT) reconstruction. However, effect of these sorting techniques on 4D dose calculation has not been explored. In this study, the authors investigated a candidate 4DCT sorting technique by comparing its 4D dose calculation accuracy with that for phase-based and amplitude-based sorting techniques.Method: An optimization model was formed using organ motion probability density function (PDF) in the 4D dose convolution. The objective function for optimization was defined as the maximum difference between the expected 4D dose in organ of interest and the 4D dose calculated using a 4DCT sorted by a candidate sampling method. Sorting samples, as optimization variables, were selected on the respiratory motion PDF assessed during the CT scanning. Breathing curves obtained from patients' 4DCT scanning, as well as 3D dose distribution from treatment planning, were used in the study. Given the objective function, a residual error analysis was performed, and k-means clustering was found to be an effective sampling scheme to improve the 4D dose calculation accuracy and independent with the patient-specific dose distribution. Results: Patient data analysis demonstrated that the k-means sampling was superior to the conventional phase-based and amplitude-based sorting and comparable to the optimal sampling results. For phase-based sorting, the residual error in 4D dose calculations may not be further reduced to an acceptable accuracy after a certain number of phases, while for amplitude-based sorting, k-means sampling, and the optimal sampling, the residual error in 4D dose calculations decreased rapidly as the number of 4DCT phases increased to 6.Conclusion: An innovative phase sorting method (k-means method) is presented in this study. The method is dependent only on tumor motion PDF. It could provide a way to refine the phase sorting in 4DCT reconstruction and is effective for

  20. Nonlinear rotor dynamics of 2D molecular array: topology reconstruction

    International Nuclear Information System (INIS)

    Molecular layers with rotational degrees of freedom and quadrupolar interaction between linear molecules are investigated theoretically. We found earlier that alternative orientation of the molecules along and perpendicular to an axis of the rectangular lattice is preferable. Here we find the integral of motion and give the topology analysis of the possible dynamical phases and special points in the long-wave limit. We find the strong anisotropy in the angle space: directions of easy excitation ('valleys') exist. We show the potential relief reconstruction in dependence on the adsorbed lattice anisotropy.

  1. Reconstructing the quantum state of a Bose-Einstein condensate of atoms in two hyperfine levels

    International Nuclear Information System (INIS)

    We describe an atomic interferometer based on Raman transitions between two hyperfine states. We show how atom count probabilities at the output of the interferometer can be used to reconstruct the joint, entangled multi-particle state of a Bose-Einstein condensate with fixed total number. Two data collection schemes are compared, by numerically solving for the density matrix from the probability data and making analytical estimates of the errors. When only the phase of the interferometer is varied, state reconstruction is possible but ill-conditioned for the case of an unbalanced beamsplitter. When both the phase and transmission parameters are varied, the two-mode Q-function can be measured directly and the reconstruction of the state is well-conditioned. (author)

  2. One-Time Key Based Phase Scrambling for Phase-Only Correlation between Visually Protected Images

    OpenAIRE

    Ito Izumi; Kiya Hitoshi

    2009-01-01

    One-time key based phase scrambling is proposed for privacy-protected image matching. The image matching is performed using invisible templates that are protected by phase scrambling. A key for phase scrambling is not required for the image matching, and the key can even be discarded after scrambling if the template does not need to be reconstructed. Theoretical analyses are presented to provide guidelines for designing key parameters that affect the visual effect and image matching. Experim...

  3. Hanford Environmental Dose Reconstruction Project

    International Nuclear Information System (INIS)

    The objective of the Hanford Environmental Dose Reconstruction (HEDR) Project is to estimate the radiation doses that individuals and populations could have received from nuclear operations at Hanford since 1944. The TSP consists of experts in environmental pathways, epidemiology, surface-water transport, ground-water transport, statistics, demography, agriculture, meteorology, nuclear engineering, radiation dosimetry, and cultural anthropology. Included are appointed technical members representing the states of Oregon, Washington, and Idaho, a representative of Native American tribes, and an individual representing the public. The project is divided into the following technical tasks. These tasks correspond to the path radionuclides followed from release to impact on humans (dose estimates): Source terms, environmental transport, environmental monitoring data, demography, food consumption, and agriculture, and environmental pathways and dose estimates. Progress is discussed

  4. Reconstruction of nonlinear wave propagation

    Science.gov (United States)

    Fleischer, Jason W; Barsi, Christopher; Wan, Wenjie

    2013-04-23

    Disclosed are systems and methods for characterizing a nonlinear propagation environment by numerically propagating a measured output waveform resulting from a known input waveform. The numerical propagation reconstructs the input waveform, and in the process, the nonlinear environment is characterized. In certain embodiments, knowledge of the characterized nonlinear environment facilitates determination of an unknown input based on a measured output. Similarly, knowledge of the characterized nonlinear environment also facilitates formation of a desired output based on a configurable input. In both situations, the input thus characterized and the output thus obtained include features that would normally be lost in linear propagations. Such features can include evanescent waves and peripheral waves, such that an image thus obtained are inherently wide-angle, farfield form of microscopy.

  5. Model Equations: "Black Box" Reconstruction

    Science.gov (United States)

    Bezruchko, Boris P.; Smirnov, Dmitry A.

    Black box reconstruction is both the most difficult and the most tempting modelling problem when any prior information about an appropriate model structure is lacking. An intriguing thing is that a model capable of reproducing an observed behaviour or predicting further evolution should be obtained only from an observed time series, i.e. "from nothing" at first sight. Chances for a success are not large. Even more so, a "good" model would become a valuable tool to characterise an object and understand its dynamics. Lack of prior information causes one to utilise universal model structures, e.g. artificial neural networks, radial basis functions and algebraic polynomials are included in the right-hand sides of dynamical model equations. Such models are often multi-dimensional and involve quite many free parameters.

  6. Image reconstruction algorithms from projections

    International Nuclear Information System (INIS)

    Many physical or bio-physical phenomena can be analysed as 'images' that is to say a bi-dimensionnal representation of a characteristic parameter of the material (density, concentration of a given element, resistivity, etc...). The various algorithms reviewed in the paper lead to a numerical reconstitution of such an image from a finite set of measurements considered as 'projections' of the initial object. We first give a physical insight then the mathematical formulation of the various concepts necessary for the presentation of the problem; after that we show why and how many reconstruction algorithms are possible. These different strategies are quickly compared chiefly according to realization facilities, structure, volume and performances (speed, accuracy) of the processing system required

  7. New algorithms for adaptive optics point-spread function reconstruction

    CERN Document Server

    Gendron, E; Fusco, T; Rousset, G; Gendron, Eric; Cl\\'{e}net, Yann; Fusco, Thierry

    2006-01-01

    Context. The knowledge of the point-spread function compensated by adaptive optics is of prime importance in several image restoration techniques such as deconvolution and astrometric/photometric algorithms. Wavefront-related data from the adaptive optics real-time computer can be used to accurately estimate the point-spread function in adaptive optics observations. The only point-spread function reconstruction algorithm implemented on astronomical adaptive optics system makes use of particular functions, named $U\\_{ij}$. These $U\\_{ij}$ functions are derived from the mirror modes, and their number is proportional to the square number of these mirror modes. Aims. We present here two new algorithms for point-spread function reconstruction that aim at suppressing the use of these $U\\_{ij}$ functions to avoid the storage of a large amount of data and to shorten the computation time of this PSF reconstruction. Methods. Both algorithms take advantage of the eigen decomposition of the residual parallel phase covari...

  8. Bayesian tomographic reconstruction of microsystems

    Science.gov (United States)

    Salem, Sofia Fekih; Vabre, Alexandre; Mohammad-Djafari, Ali

    2007-11-01

    The microtomography by X ray transmission plays an increasingly dominating role in the study and the understanding of microsystems. Within this framework, an experimental setup of high resolution X ray microtomography was developed at CEA-List to quantify the physical parameters related to the fluids flow in microsystems. Several difficulties rise from the nature of experimental data collected on this setup: enhanced error measurements due to various physical phenomena occurring during the image formation (diffusion, beam hardening), and specificities of the setup (limited angle, partial view of the object, weak contrast). To reconstruct the object we must solve an inverse problem. This inverse problem is known to be ill-posed. It therefore needs to be regularized by introducing prior information. The main prior information we account for is that the object is composed of a finite known number of different materials distributed in compact regions. This a priori information is introduced via a Gauss-Markov field for the contrast distributions with a hidden Potts-Markov field for the class materials in the Bayesian estimation framework. The computations are done by using an appropriate Markov Chain Monte Carlo (MCMC) technique. In this paper, we present first the basic steps of the proposed algorithms. Then we focus on one of the main steps in any iterative reconstruction method which is the computation of forward and adjoint operators (projection and backprojection). A fast implementation of these two operators is crucial for the real application of the method. We give some details on the fast computation of these steps and show some preliminary results of simulations.

  9. Proximal Gastrojejunal Reconstruction after Pancreaticoduodenal Resection

    Directory of Open Access Journals (Sweden)

    M. Wayne

    2012-01-01

    Full Text Available Introduction. Reconstruction by proximal gastrojejunostomy, and distal biliary and pancreatic anastomoses is infrequently used after resection of the head of the pancreas because of fear of fistulas and cholangitis. Pancreaticoduodenectomy is being performed more frequently for cystic malignant and premalignant lesions. Because of this there is a need for endoscopic visualization and biopsy of the residual pancreatic duct, since multi-centricity is characteristic of some of these malignancies. Since endoscopic access of the bile duct and pancreatic duct is difficult and unsuccessful in 50–70% after B II or Roux Y reconstruction, we prospectively studied the merit and complications (early and late of proximal gastrojejunal (PGJ reconstruction after pancreaticoduodenal resection. Material and Methods. Thirty nine consecutive, non-radomized patients underwent pancreaticoduodenectomy and PGJ reconstruction over 14 mos. There were 21 males and 18 females. Results. 7 patients with IPMN have undergone repeat CT scanning for surveillance, with 3 requiring repeat EUS and ERCP. There were no technical difficulties accessing the pancreas or the pancreatic duct, supporting the PGJ reconstruction. Conclusion. Proximal gastrojejunal reconstruction following pancreaticoduodenal resection may be safely done with similar morbidity to traditional pancreaticojejunal reconstructions. PGJ reconstruction may be of greater value when direct visual access to the bile duct or pancreatic duct is necessary, and should be considered when doing resection for mucinous cysts or IPMN of the head of the pancreas.

  10. Noise-enhanced reconstruction of attractors

    CERN Document Server

    Castro, R G

    1997-01-01

    In principle, the state space of a chaotic attractor can be partially or wholly reconstructed from interspike intervals recorded from experiment. Under certain conditions, the quality of a partial reconstruction, as measured by the spike train prediction error, can be increased by adding noise to the spike creation process. This phenomenon for chaotic systems is an analogue of stochastic resonance.

  11. Labral reconstruction: when to perform and how

    Directory of Open Access Journals (Sweden)

    Brian J White

    2015-07-01

    Full Text Available Over the past decade, the understanding of the anatomy and function of the hip joint has continuously evolved, and surgical treatment options for the hip have significantly progressed. Originally, surgical treatment of the hip primarily involved resection of damaged tissue. Procedures that maintain and preserve proper hip anatomy, such as labral repair and femoroacetabular impingement (FAI correction, have shown superior results, in terms of pain reduction, increased function, and ability to return to activities. Labral reconstruction is a treatment option that uses a graft to reconstruct the native labrum. The technique and outcomes of labral reconstruction have been described relatively recently, and labral reconstruction is a cutting edge procedure that has shown promising early outcomes. The aim of this article is to review the current literature on hip labral reconstruction. We will review the indications for labral reconstruction, surgical technique and graft options, and surgical outcomes that have been described to date. Labral reconstruction provides an alternative treatment option for challenging intra-articular hip problems. Labral reconstruction restores the original anatomy of the hip and has the potential to preserve the longevity of the hip joint. This technique is an important tool in the orthopaedic surgeon’s arsenal for hip joint treatment and preservation.

  12. 3D Reconstruction of NMR Images

    OpenAIRE

    Peter Izak; Milan Smetana; Libor Hargas; Miroslav Hrianka; Pavol Spanik

    2007-01-01

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

  13. Tomography Reconstruction with Noisy Projection Data

    Institute of Scientific and Technical Information of China (English)

    LI Xide

    2000-01-01

    Computerized tomography (CT) based on the convolution back projection method has been regarded as an important reconstruction method, but it is not suitable to noisy conditions. In this paper, techniques of filtering, resampling and frequency shifting have been introduced to enhance the quality of CT reconstruction and improved results have been obtained.

  14. Acellular Dermal Matrix in Postmastectomy Breast Reconstruction

    NARCIS (Netherlands)

    A.M.S. Ibrahim (Ahmed)

    2014-01-01

    markdownabstract__Abstract__ Over the last decade the use of acellular dermal matrix (ADM) in reconstructive breast surgery has been transformative. Some authors have gone as far as to suggest that it is the single most important advancement in prosthetic breast reconstruction. ADMs are able to pro

  15. Component Separation for Complex Abdominal Wall Reconstruction

    Medline Plus

    Full Text Available COMPONENT SEPARATION FOR COMPLEX ABDOMINAL WALL RECONSTRUCTION ALBANY MEDICAL CENTER ALBANY, NY April 30, 2008 00:00:07 ANNOUNCER: This event is being ... the premiere webcast of a component separation for complex abdominal-wall reconstruction, performed by Dr. Jerome D. ...

  16. Reconstructing magma reservoir dynamics from field evidence

    Science.gov (United States)

    Verberne, R.; Muntener, O.; Ulmer, P.

    2013-12-01

    Reconstructing the dynamics within magma reservoirs during and after emplacement greatly enhance our understanding of their formation and evolution. By determining the length and timescales over which magma remains mobile within magma reservoirs, fluxes of magma that is possibly extractable can be quantified, providing a link between plutonic and volcanic systems, and constraints on the likelihood of a pluton feeding volcanic eruptions. However, the general absence of marker beds and uncertainties regarding at which crystal fractions super-solidus foliation patterns are recorded make it difficult to reconstruct and quantify deformation inside plutons, especially the deformation that occurred at low crystal fractions. Here we present a case study of the Listino Ring Structure (LRS) of the Adamello Batholith in N-Italy, a 300-500 m-wide semi-circular zone of intensely foliated tonalite containing abundant evidence for magmatic deformation and magma mingling (Brack, 1984). The differences in the interaction between felsic and mafic magmas recorded in the form of mafic dikes, sheets and enclaves can be used to determine spatial and/or temporal differences of magma rheology during evolution of the reservoir. Detailed field mapping shows a clear difference in intrusion style between the southern and eastern sides of the LRS, as mafic magma intrudes into different felsic host magmas. An attempt is made to quantify these differences in terms of the physical state of the host magmas, using a variety of analyses pertaining to the breakup of mafic dikes into enclaves, the assimilation of phenocrysts from the host magma by the mafic magma, and the back-veining of mafic dikes and enclaves. The common component of these analyses is a parametrization of the phase petrology of the magmas as a function of temperature, which allows for the determination of melt fraction and composition at super-solidus conditions, from which physical properties such as density and viscosity can be

  17. Uniqueness transition in noisy phase retrieval

    International Nuclear Information System (INIS)

    Previous criteria for the feasibility of reconstructing phase information from intensity measurements, both in x-ray crystallography and more recently in coherent x-ray imaging, have been based on the Maxwell constraint counting principle. We propose a new criterion, based on Shannon's mutual information, that is better suited for noisy data or contrast that has strong priors not well modeled by continuous variables. A natural application is magnetic domain imaging, where the criterion for uniqueness in the reconstruction takes the form that the number of photons, per pixel of contrast in the image, exceeds a certain minimum. Through detailed studies of a simple model, we develop an analogy between reconstruction uniqueness and the phases of a spin glass.

  18. Track reconstruction in CMS high luminosity environment

    CERN Document Server

    Goetzmann, Christophe

    2014-01-01

    The CMS tracker is the largest silicon detector ever built, covering 200 square meters and providing an average of 14 high-precision measurements per track. Tracking is essential for the reconstruction of objects like jets, muons, electrons and tau leptons starting from the raw data from the silicon pixel and strip detectors. Track reconstruction is widely used also at trigger level as it improves objects tagging and resolution.The CMS tracking code is organized in several levels, known as iterative steps, each optimized to reconstruct a class of particle trajectories, as the ones of particles originating from the primary vertex or displaced tracks from particles resulting from secondary vertices. Each iterative step consists of seeding, pattern recognition and fitting by a kalman filter, and a final filtering and cleaning. Each subsequent step works on hits not yet associated to a reconstructed particle trajectory.The CMS tracking code is continuously evolving to make the reconstruction computing load compat...

  19. Dimensionality reduction via locally reconstructive patch alignment

    Science.gov (United States)

    Chen, Yi; Yin, Jun; Zhu, Jie; Jin, Zhong

    2012-07-01

    Based on the local patch concept, we proposed locally reconstructive patch alignment (LRPA) for dimensionality reduction. For each patch, LRPA aims to find the low-dimensional subspace in which the reconstruction error of the within-class nearest neighbors is minimized and the reconstruction error of the between-class nearest neighbors is maximized. LRPA preserves the local structure hidden in the high-dimensional space. More importantly, LRPA has natural connections with linear regression classification (LRC). While LRC uses reconstruction errors as the classification rule, a sample can be classified correctly when the within-class reconstruction error is minimal. The goal of LRPA makes it cooperate well with LRC. The experimental results on the extended Yale B (YALE-B), AR, PolyU finger knuckle print, and the palm print databases demonstrate LRPA plus LRC is an effective and robust pattern-recognition system.

  20. Bayesian image reconstruction: Application to emission tomography

    Energy Technology Data Exchange (ETDEWEB)

    Nunez, J.; Llacer, J.

    1989-02-01

    In this paper we propose a Maximum a Posteriori (MAP) method of image reconstruction in the Bayesian framework for the Poisson noise case. We use entropy to define the prior probability and likelihood to define the conditional probability. The method uses sharpness parameters which can be theoretically computed or adjusted, allowing us to obtain MAP reconstructions without the problem of the grey'' reconstructions associated with the pre Bayesian reconstructions. We have developed several ways to solve the reconstruction problem and propose a new iterative algorithm which is stable, maintains positivity and converges to feasible images faster than the Maximum Likelihood Estimate method. We have successfully applied the new method to the case of Emission Tomography, both with simulated and real data. 41 refs., 4 figs., 1 tab.