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Sample records for direct imaging di

  1. Direct imaging of exoplanets.

    PubMed

    Lagrange, Anne-Marie

    2014-04-28

    Most of the exoplanets known today have been discovered by indirect techniques, based on the study of the host star radial velocity or photometric temporal variations. These detections allowed the study of the planet populations in the first 5-8 AU from the central stars and have provided precious information on the way planets form and evolve at such separations. Direct imaging on 8-10 m class telescopes allows the detection of giant planets at larger separations (currently typically more than 5-10 AU) complementing the indirect techniques. So far, only a few planets have been imaged around young stars, but each of them provides an opportunity for unique dedicated studies of their orbital, physical and atmospheric properties and sometimes also on the interaction with the 'second-generation', debris discs. These few detections already challenge formation theories. In this paper, I present the results of direct imaging surveys obtained so far, and what they already tell us about giant planet (GP) formation and evolution. Individual and emblematic cases are detailed; they illustrate what future instruments will routinely deliver for a much larger number of stars. I also point out the limitations of this approach, as well as the needs for further work in terms of planet formation modelling. I finally present the progress expected in direct imaging in the near future, thanks in particular to forthcoming planet imagers on 8-10 m class telescopes. PMID:24664924

  2. Direct Imaging of Faint Companions

    NASA Astrophysics Data System (ADS)

    Claudi, Riccardo

    The exoplanets around stars in the solar neighborhood are expected to be bright enough for us to characterize them with direct imaging; however, they are much fainter than their parent stars, and separated by very small angles, so conventional imaging techniques are totally inadequate, and new methods are needed. The direct imaging of exoplanets is extremely challenging. Jupiter is 109 times fainter than our Sun in reflected visible light. A direct imaging instrument for exoplanets must suppress (1) the bright star image and diffraction pattern and (2) the stellar scattered light from imperfections in the telescope. The main goal of high-contrast imaging is primarily to discover and characterize extrasolar planetary systems. High-contrast observations, in optical and infrared astronomy, are defined as any observation requiring a technique to reveal a low mass companion that is so close to the primary, brighter by a factor of at least 105, that optical effects hinder or prevent the collection of photons directly from the target of observation. To overcome this, astronomers combined large telescopes (to reduce the impact of diffraction), adaptive optics (to correct for phase errors induced by atmospheric turbulence), and sophisticated image processing.

  3. Doppler images of DI Piscium during 2004-2006

    NASA Astrophysics Data System (ADS)

    Lindborg, M.; Hackman, T.; Mantere, M. J.; Korhonen, H.; Ilyin, I.; Kochukhov, O.; Piskunov, N.

    2014-02-01

    Aims: DI Psc (HD 217352) is a Li-rich, rapidly rotating single K giant. We set out to study the spot configuration and activity level by calculating surface temperature maps of the star. Methods: We apply the Doppler imaging method on high-resolution optical spectroscopy obtained during 2004-2006. Results: In July-August 2004, no clear spot structures were visible, but the spot coverage increased in July 2005, and cool spots emerged, especially at intermediate latitudes. Later on in September 2006, the spot coverage increased and cool spots were visible on both sides of the equator. However, the map of 2006 suffers from bad phase coverage, meaning it is not possible to draw definite conclusions on the spot locations during that season. Conclusions: Compared with earlier Doppler maps of DI Psc and temperature maps obtained for other late-type stars with similar rotation rates, DI Psc seems to be in a low activity state especially during the observing season of July-August 2004. During the 2005 and 2006 observing seasons, the spot activity seen in the spectral line profiles and inferred from Doppler images increases, and the temperature contrast in our last map is more comparable to what was reported in an earlier study. Therefore, it can be concluded that the spot activity level of the star is variable over time. However, the present and previous Doppler images form too short a time series to draw conclusions about a possible activity cycle in DI Psc. Based on observations made with the Nordic Optical Telescope, operated on the island of La Palma jointly by Denmark, Finland, Iceland, Norway, and Sweden in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias.

  4. MAPPING DIRECTLY IMAGED GIANT EXOPLANETS

    SciTech Connect

    Kostov, Veselin; Apai, Daniel

    2013-01-01

    With the increasing number of directly imaged giant exoplanets, the current atmosphere models are often not capable of fully explaining the spectra and luminosity of the sources. A particularly challenging component of the atmosphere models is the formation and properties of condensate cloud layers, which fundamentally impact the energetics, opacity, and evolution of the planets. Here we present a suite of techniques that can be used to estimate the level of rotational modulations these planets may show. We propose that the time-resolved observations of such periodic photometric and spectroscopic variations of extrasolar planets due to their rotation can be used as a powerful tool to probe the heterogeneity of their optical surfaces. In this paper, we develop simulations to explore the capabilities of current and next-generation ground- and space-based instruments for this technique. We address and discuss the following questions: (1) what planet properties can be deduced from the light curve and/or spectra, and in particular can we determine rotation periods, spot coverage, spot colors, and spot spectra?; (2) what is the optimal configuration of instrument/wavelength/temporal sampling required for these measurements?; and (3) can principal component analysis be used to invert the light curve and deduce the surface map of the planet? Our simulations describe the expected spectral differences between homogeneous (clear or cloudy) and patchy atmospheres, outline the significance of the dominant absorption features of H{sub 2}O, CH{sub 4}, and CO, and provide a method to distinguish these two types of atmospheres. Assuming surfaces with and without clouds for most currently imaged planets the current models predict the largest variations in the J band. Simulated photometry from current and future instruments is used to estimate the level of detectable photometric variations. We conclude that future instruments will be able to recover not only the rotation periods

  5. Directional emittance corrections for thermal infrared imaging

    NASA Technical Reports Server (NTRS)

    Daryabeigi, Kamran; Wright, Robert E., Jr.; Puram, Chith K.; Alderfer, David W.

    1992-01-01

    A simple measurement technique for measuring the variation of directional emittance of surfaces at various temperatures using commercially available radiometric IR imaging systems was developed and tested. This technique provided the integrated value of directional emittance over the spectral bandwidth of the IR imaging system. The directional emittance of flat black lacquer and red stycast, an epoxy resin, measured using this technique were in good agreement with the predictions of the electromagnetic theory. The data were also in good agreement with directional emittance data inferred from directional reflectance measurements made on a spectrophotometer.

  6. Image rejects in general direct digital radiography

    PubMed Central

    Rosanowsky, Tine Blomberg; Jensen, Camilla; Wah, Kenneth Hong Ching

    2015-01-01

    Background The number of rejected images is an indicator of image quality and unnecessary imaging at a radiology department. Image reject analysis was frequent in the film era, but comparably few and small studies have been published after converting to digital radiography. One reason may be a belief that rejects have been eliminated with digitalization. Purpose To measure the extension of deleted images in direct digital radiography (DR), in order to assess the rates of rejects and unnecessary imaging and to analyze reasons for deletions, in order to improve the radiological services. Material and Methods All exposed images at two direct digital laboratories at a hospital in Norway were reviewed in January 2014. Type of examination, number of exposed images, and number of deleted images were registered. Each deleted image was analyzed separately and the reason for deleting the image was recorded. Results Out of 5417 exposed images, 596 were deleted, giving a deletion rate of 11%. A total of 51.3% were deleted due to positioning errors and 31.0% due to error in centering. The examinations with the highest percentage of deleted images were the knee, hip, and ankle, 20.6%, 18.5%, and 13.8% respectively. Conclusion The reject rate is at least as high as the deletion rate and is comparable with previous film-based imaging systems. The reasons for rejection are quite different in digital systems. This falsifies the hypothesis that digitalization would eliminates rejects. A deleted image does not contribute to diagnostics, and therefore is an unnecessary image. Hence, the high rates of deleted images have implications for management, training, education, as well as for quality. PMID:26500784

  7. Circular Data Images for Directional Data

    NASA Technical Reports Server (NTRS)

    Morpet, William J.

    2004-01-01

    Directional data includes vectors, points on a unit sphere, axis orientation, angular direction, and circular or periodic data. The theoretical statistics for circular data (random points on a unit circle) or spherical data (random points on a unit sphere) are a recent development. An overview of existing graphical methods for the display of directional data is given. Cross-over occurs when periodic data are measured on a scale for the measurement of linear variables. For example, if angle is represented by a linear color gradient changing uniformly from dark blue at -180 degrees to bright red at +180 degrees, the color image will be discontinuous at +180 degrees and -180 degrees, which are the same location. The resultant color would depend on the direction of approach to the cross-over point. A new graphical method for imaging directional data is described, which affords high resolution without color discontinuity from "cross-over". It is called the circular data image. The circular data image uses a circular color scale in which colors repeat periodically. Some examples of the circular data image include direction of earth winds on a global scale, rocket motor internal flow, earth global magnetic field direction, and rocket motor nozzle vector direction vs. time.

  8. The structure of DNA by direct imaging

    PubMed Central

    Marini, Monica; Falqui, Andrea; Moretti, Manola; Limongi, Tania; Allione, Marco; Genovese, Alessandro; Lopatin, Sergei; Tirinato, Luca; Das, Gobind; Torre, Bruno; Giugni, Andrea; Gentile, Francesco; Candeloro, Patrizio; Di Fabrizio, Enzo

    2015-01-01

    The structure of DNA was determined in 1953 by x-ray fiber diffraction. Several attempts have been made to obtain a direct image of DNA with alternative techniques. The direct image is intended to allow a quantitative evaluation of all relevant characteristic lengths present in a molecule. A direct image of DNA, which is different from diffraction in the reciprocal space, is difficult to obtain for two main reasons: the intrinsic very low contrast of the elements that form the molecule and the difficulty of preparing the sample while preserving its pristine shape and size. We show that through a preparation procedure compatible with the DNA physiological conditions, a direct image of a single suspended DNA molecule can be obtained. In the image, all relevant lengths of A-form DNA are measurable. A high-resolution transmission electron microscope that operates at 80 keV with an ultimate resolution of 1.5 Å was used for this experiment. Direct imaging of a single molecule can be used as a method to address biological problems that require knowledge at the single-molecule level, given that the average information obtained by x-ray diffraction of crystals or fibers is not sufficient for detailed structure determination, or when crystals cannot be obtained from biological molecules or are not sufficient in understanding multiple protein configurations. PMID:26601243

  9. The structure of DNA by direct imaging.

    PubMed

    Marini, Monica; Falqui, Andrea; Moretti, Manola; Limongi, Tania; Allione, Marco; Genovese, Alessandro; Lopatin, Sergei; Tirinato, Luca; Das, Gobind; Torre, Bruno; Giugni, Andrea; Gentile, Francesco; Candeloro, Patrizio; Di Fabrizio, Enzo

    2015-08-01

    The structure of DNA was determined in 1953 by x-ray fiber diffraction. Several attempts have been made to obtain a direct image of DNA with alternative techniques. The direct image is intended to allow a quantitative evaluation of all relevant characteristic lengths present in a molecule. A direct image of DNA, which is different from diffraction in the reciprocal space, is difficult to obtain for two main reasons: the intrinsic very low contrast of the elements that form the molecule and the difficulty of preparing the sample while preserving its pristine shape and size. We show that through a preparation procedure compatible with the DNA physiological conditions, a direct image of a single suspended DNA molecule can be obtained. In the image, all relevant lengths of A-form DNA are measurable. A high-resolution transmission electron microscope that operates at 80 keV with an ultimate resolution of 1.5 Å was used for this experiment. Direct imaging of a single molecule can be used as a method to address biological problems that require knowledge at the single-molecule level, given that the average information obtained by x-ray diffraction of crystals or fibers is not sufficient for detailed structure determination, or when crystals cannot be obtained from biological molecules or are not sufficient in understanding multiple protein configurations. PMID:26601243

  10. Directional Joint Bilateral Filter for Depth Images

    PubMed Central

    Le, Anh Vu; Jung, Seung-Won; Won, Chee Sun

    2014-01-01

    Depth maps taken by the low cost Kinect sensor are often noisy and incomplete. Thus, post-processing for obtaining reliable depth maps is necessary for advanced image and video applications such as object recognition and multi-view rendering. In this paper, we propose adaptive directional filters that fill the holes and suppress the noise in depth maps. Specifically, novel filters whose window shapes are adaptively adjusted based on the edge direction of the color image are presented. Experimental results show that our method yields higher quality filtered depth maps than other existing methods, especially at the edge boundaries. PMID:24971470

  11. Directional joint bilateral filter for depth images.

    PubMed

    Le, Anh Vu; Jung, Seung-Won; Won, Chee Sun

    2014-01-01

    Depth maps taken by the low cost Kinect sensor are often noisy and incomplete. Thus, post-processing for obtaining reliable depth maps is necessary for advanced image and video applications such as object recognition and multi-view rendering. In this paper, we propose adaptive directional filters that fill the holes and suppress the noise in depth maps. Specifically, novel filters whose window shapes are adaptively adjusted based on the edge direction of the color image are presented. Experimental results show that our method yields higher quality filtered depth maps than other existing methods, especially at the edge boundaries. PMID:24971470

  12. Direct labeling and visualization of blood vessels with lipophilic carbocyanine dye DiI.

    PubMed

    Li, Yiwen; Song, Ying; Zhao, Lian; Gaidosh, Gabriel; Laties, Alan M; Wen, Rong

    2008-01-01

    We describe a protocol to rapidly and reliably visualize blood vessels in experimental animals. Blood vessels are directly labeled by cardiac perfusion using a specially formulated aqueous solution containing 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate (DiI), a lipophilic carbocyanine dye, which incorporates into endothelial cell membranes upon contact. By lateral diffusion, DiI also stains membrane structures, including angiogenic sprouts and pseudopodial processes that are not in direct contact. Tissues can be immediately examined by conventional and confocal fluorescence microscopy. High-quality serial optical sections using confocal microscopy are obtainable from thick tissue sections, especially at low magnification, for three-dimensional reconstruction. It takes less than 1 h to stain the vasculature in a whole animal. Compared with alternative techniques to visualize blood vessels, including space-occupying materials such as India ink or fluorescent dye-conjugated dextran, the corrosion casting technique, endothelial cell-specific markers and lectins, the present method simplifies the visualization of blood vessels and data analysis. PMID:18846097

  13. [Direct and indirect mucosal wave imaging techniques].

    PubMed

    Krasnodębska, Paulina; Szkiełkowska, Agata

    2016-04-01

    The vocal folds play a key role in the process of phonation. Cyclical movements of the vocal folds model a space called glottis, what leads to voice formation. The space contains surface between the vocal folds and the inner surface of the arytenoid cartilages. The best indicator of the vocal folds vibratory function is the mucosal wave. The presence and size of the mucosal wave is widely recognized as an indicator of tension and plasticity of vocal folds. It is also essential in the process of creating a proper, resonant voice. In the article, current knowledge of mucosal wave imaging techniques is given. Imaging can be carried out directly and indirectly. Among the direct methods, the following are distinguished: laryngostroboscopy, laryngovideostroboscopy, videokymography and high-speed digital imaging. Indirect methods include: electroglottography, photoglottography and ultrasonography. PMID:27137829

  14. Exoplanet Community Report on Direct Optical Imaging

    NASA Astrophysics Data System (ADS)

    Soummer, Remi; Levine, M.; Exoplanet Forum Direct Optical Imaging Group

    2009-01-01

    Direct Optical Imaging is necessary to characterize exoplanets spectroscopically in most cases (non-transiting planets), and to address the habitability of terrestrial planets around sun like stars. The chapter studies the science objectives, observatory architectures, and needed technology developments as a function of mission scale. Possible architectures can be based on internal coronagraphs or external occulters. The Optical Imaging chapter details the association between Astrometry or RV and imaging in space, expanding on the ExoPTF recommendations for flagship and probe-scale missions. Indirect methods (astrometry or radial velocities) are necessary to obtain a direct measurement of the masses, orbital parameters, and planet "addresses". Careful Design Reference Mission (DRM) development over the next several years will articulate the tradeoffs in cost and performance between imaging missions with and without astrometric precursors. In the short term a probe-scale direct imaging mission can be combined with existing and future Radial Velocities and ground-based Astrometry for the characterization of mature giant planets, Neptunes, and super Earths. A probe scale will also detect and characterize exozodiacal disks, a problem ExoPTF identified as critical for future terrestrial planet imaging missions. This strategy is independent from a space astrometric mission both in terms of scientific goals and timing sequence. The chapter also identifies the critical technologies for the various imaging architectures, for which the maturity is linked to flight requirements ranging from probe-scale to flagship. The chapter provides a brief overview of each technology and its state-of the-art.

  15. Alternating direction method for balanced image restoration.

    PubMed

    Xie, Shoulie; Rahardja, Susanto

    2012-11-01

    This paper presents an efficient algorithm for solving a balanced regularization problem in the frame-based image restoration. The balanced regularization is usually formulated as a minimization problem, involving an l(2) data-fidelity term, an l(1) regularizer on sparsity of frame coefficients, and a penalty on distance of sparse frame coefficients to the range of the frame operator. In image restoration, the balanced regularization approach bridges the synthesis-based and analysis-based approaches, and balances the fidelity, sparsity, and smoothness of the solution. Our proposed algorithm for solving the balanced optimal problem is based on a variable splitting strategy and the classical alternating direction method. This paper shows that the proposed algorithm is fast and efficient in solving the standard image restoration with balanced regularization. More precisely, a regularized version of the Hessian matrix of the l(2) data-fidelity term is involved, and by exploiting the related fast tight Parseval frame and the special structures of the observation matrices, the regularized Hessian matrix can perform quite efficiently for the frame-based standard image restoration applications, such as circular deconvolution in image deblurring and missing samples in image inpainting. Numerical simulations illustrate the efficiency of our proposed algorithm in the frame-based image restoration with balanced regularization. PMID:22752137

  16. Vibrio cholerae VpsT Regulates Matrix Production and Motility by Directly Sensing Cyclic di-GMP

    SciTech Connect

    Krasteva, P.; Fong, J; Shikuma, N; Beyhan, S; Navarro, M; Yildiz, F; Sondermann, H

    2010-01-01

    Microorganisms can switch from a planktonic, free-swimming life-style to a sessile, colonial state, called a biofilm, which confers resistance to environmental stress. Conversion between the motile and biofilm life-styles has been attributed to increased levels of the prokaryotic second messenger cyclic di-guanosine monophosphate (c-di-GMP), yet the signaling mechanisms mediating such a global switch are poorly understood. Here we show that the transcriptional regulator VpsT from Vibrio cholerae directly senses c-di-GMP to inversely control extracellular matrix production and motility, which identifies VpsT as a master regulator for biofilm formation. Rather than being regulated by phosphorylation, VpsT undergoes a change in oligomerization on c-di-GMP binding.

  17. Quantum unidirectional rotation directly imaged with molecules

    PubMed Central

    Mizuse, Kenta; Kitano, Kenta; Hasegawa, Hirokazu; Ohshima, Yasuhiro

    2015-01-01

    A gas-phase molecular ensemble coherently excited to have an oriented rotational angular momentum has recently emerged as an appropriate microscopic system to illustrate quantum mechanical behavior directly linked to classical rotational motion, which has a definite direction. To realize an intuitive visualization of such a unidirectional molecular rotation, we report high-resolution direct imaging of direction-controlled rotational wave packets in nitrogen molecules. The rotational direction was regulated by a pair of time-delayed, polarization-skewed laser pulses, introducing the dynamic chirality to the system. The subsequent spatiotemporal propagation was tracked by a newly developed Coulomb explosion imaging setup. From the observed molecular movie, time-dependent detailed nodal structures, instantaneous alignment, angular dispersion, and fractional revivals of the wave packet are fully characterized while the ensemble keeps rotating in one direction. The present approach, providing an accurate view on unidirectional rotation in quantum regime, will guide more sophisticated molecular manipulations by utilizing its capability in capturing highly structured spatiotemporal evolution of molecular wave packets. PMID:26601205

  18. DIRECTLY IMAGING TIDALLY POWERED MIGRATING JUPITERS

    SciTech Connect

    Dong Subo; Katz, Boaz; Socrates, Aristotle

    2013-01-10

    Upcoming direct-imaging experiments may detect a new class of long-period, highly luminous, tidally powered extrasolar gas giants. Even though they are hosted by {approx} Gyr-'old' main-sequence stars, they can be as 'hot' as young Jupiters at {approx}100 Myr, the prime targets of direct-imaging surveys. They are on years-long orbits and presently migrating to 'feed' the 'hot Jupiters'. They are expected from 'high-e' migration mechanisms, in which Jupiters are excited to highly eccentric orbits and then shrink semimajor axis by a factor of {approx}10-100 due to tidal dissipation at close periastron passages. The dissipated orbital energy is converted to heat, and if it is deposited deep enough into the atmosphere, the planet likely radiates steadily at luminosity L {approx} 100-1000 L{sub Jup}(2 Multiplication-Sign 10{sup -7}-2 Multiplication-Sign 10{sup -6} L{sub Sun }) during a typical {approx} Gyr migration timescale. Their large orbital separations and expected high planet-to-star flux ratios in IR make them potentially accessible to high-contrast imaging instruments on 10 m class telescopes. {approx}10 such planets are expected to exist around FGK dwarfs within {approx}50 pc. Long-period radial velocity planets are viable candidates, and the highly eccentric planet HD 20782b at maximum angular separation {approx}0.''08 is a promising candidate. Directly imaging these tidally powered Jupiters would enable a direct test of high-e migration mechanisms. Once detected, the luminosity would provide a direct measurement of the migration rate, and together with mass (and possibly radius) estimate, they would serve as a laboratory to study planetary spectral formation and tidal physics.

  19. Direct imaging of extra-solar planets

    SciTech Connect

    Olivier, S.S.; Max, V.E.; Brase, J.M.; Caffano, C.J.; Gavel, D.T.; Macintosh, B.A.

    1997-03-01

    Direct imaging of extra-solar planets may be possible with the new generation of large ground-based telescopes equipped with state- of- the-art adaptive optics (AO) systems to compensate for the blurring effect of the Earth`s atmosphere. The first of these systems is scheduled to begin operation in 1998 on the 10 in Keck II telescope. In this paper, general formulas for high-contrast imaging with AO systems are presented and used to calculate the sensitivity of the Keck AO system. The results of these calculations show that the Keck AO system should achieve the sensitivity necessary to detect giant planets around several nearby bright stars.

  20. Two Mirrors: Infinite Images of DiCaprio

    ERIC Educational Resources Information Center

    Fadeev, Pavel

    2015-01-01

    Movies are mostly viewed for entertainment. Mixing entertainment and physics gets students excited as we look at a famous movie scene from a different point of view. The following is a link to a fragment from the 2010 motion picture "Inception": http://www.youtube.com/watch?v=q3tBBhYJeAw. The following problem, based on images in facing…

  1. Two Mirrors: Infinite Images of DiCaprio

    NASA Astrophysics Data System (ADS)

    Fadeev, Pavel

    2015-11-01

    Movies are mostly viewed for entertainment. Mixing entertainment and physics gets students excited as we look at a famous movie scene from a different point of view. The following is a link to a fragment from the 2010 motion picture "Inception": http://www.youtube.com/watch?v=q3tBBhYJeAw. The following problem, based on images in facing mirrors from that movie, was given to high school students studying geometric objects.

  2. Direct Exoplanet Detection with Binary Differential Imaging

    NASA Astrophysics Data System (ADS)

    Rodigas, Timothy J.; Weinberger, Alycia; Mamajek, Eric E.; Males, Jared R.; Close, Laird M.; Morzinski, Katie; Hinz, Philip M.; Kaib, Nathan

    2015-10-01

    Binaries are typically excluded from direct imaging exoplanet surveys. However, the recent findings of Kepler and radial velocity programs show that planets can and do form in binary systems. Here, we suggest that visual binaries offer unique advantages for direct imaging. We show that Binary Differential Imaging (BDI), whereby two stars are imaged simultaneously at the same wavelength within the isoplanatic patch at a high Strehl ratio, offers improved point spread function (PSF) subtraction that can result in increased sensitivity to planets close to each star. We demonstrate this by observing a young visual binary separated by 4″ with MagAO/Clio-2 at 3.9 μm, where the Strehl ratio is high, the isoplanatic patch is large, and giant planets are bright. Comparing BDI to angular differential imaging (ADI), we find that BDI’s 5σ contrast is ˜0.5 mag better than ADI’s within ˜1″ for the particular binary we observed. Because planets typically reside close to their host stars, BDI is a promising technique for discovering exoplanets in stellar systems that are often ignored. BDI is also 2-4× more efficient than ADI and classical reference PSF subtraction, since planets can be detected around both the target and PSF reference simultaneously. We are currently exploiting this technique in a new MagAO survey for giant planets in 140 young nearby visual binaries. BDI on a space-based telescope would not be limited by isoplanatism effects and would therefore be an even more powerful tool for imaging and discovering planets. This paper includes data obtained at the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile.

  3. Transdermal Uptake of Diethyl Phthalate and Di(n-butyl) Phthalate Directly from Air: Experimental Verification

    PubMed Central

    Bekö, Gabriel; Koch, Holger M.; Salthammer, Tunga; Schripp, Tobias; Toftum, Jørn; Clausen, Geo

    2015-01-01

    Background Fundamental considerations indicate that, for certain phthalate esters, dermal absorption from air is an uptake pathway that is comparable to or greater than inhalation. Yet this pathway has not been experimentally evaluated and has been largely overlooked when assessing uptake of phthalate esters. Objectives This study investigated transdermal uptake, directly from air, of diethyl phthalate (DEP) and di(n-butyl) phthalate (DnBP) in humans. Methods In a series of experiments, six human participants were exposed for 6 hr in a chamber containing deliberately elevated air concentrations of DEP and DnBP. The participants either wore a hood and breathed air with phthalate concentrations substantially below those in the chamber or did not wear a hood and breathed chamber air. All urinations were collected from initiation of exposure until 54 hr later. Metabolites of DEP and DnBP were measured in these samples and extrapolated to parent phthalate intakes, corrected for background and hood air exposures. Results For DEP, the median dermal uptake directly from air was 4.0 μg/(μg/m3 in air) compared with an inhalation intake of 3.8 μg/(μg/m3 in air). For DnBP, the median dermal uptake from air was 3.1 μg/(μg/m3 in air) compared with an inhalation intake of 3.9 μg/(μg/m3 in air). Conclusions This study shows that dermal uptake directly from air can be a meaningful exposure pathway for DEP and DnBP. For other semivolatile organic compounds (SVOCs) whose molecular weight and lipid/air partition coefficient are in the appropriate range, direct absorption from air is also anticipated to be significant. Citation Weschler CJ, Bekö G, Koch HM, Salthammer T, Schripp T, Toftum J, Clausen G. 2015. Transdermal uptake of diethyl phthalate and di(n-butyl) phthalate directly from air: experimental verification. Environ Health Perspect 123:928–934; http://dx.doi.org/10.1289/ehp.1409151 PMID:25850107

  4. Weighting interferometric data for direct imaging

    NASA Astrophysics Data System (ADS)

    Boone, Frédéric

    2013-08-01

    The new generation interferometric arrays such as the Atacama Large Millimeter/submillimeter Array (ALMA) are composed of a large number of telescopes and their configurations are optimized for Fourier plane (a.k.a. uv-plane) coverage. As a consequence, solving for the missing information in the uv-plane is becoming less critical and the imaging algorithms can be revisited. The situation is getting similar to that encountered with single filled aperture telescopes and it is becoming possible to make images in a direct way. In this article a new weighting method is introduced to obtain "pseudo-clean" images without using prior information to solve for the Fourier transform of the source. This method is similar but not equivalent to the successive application of robust weighting and tapering at different scales. The idea is to weight the data to compensate for the imperfect distribution of natural weights in the uv-plane. The price to pay for this direct imaging technique is that the final point spread function (PSF or beam) may not follow a simple analytical shape such as a Gaussian (but this is also the case in optical astronomy) and some sensitivity is lost (but this is the case with any imaging algorithm in interferometry). Two parameters are introduced to control the trade-off between imaging quality and sensitivity, namely a threshold parameter and a coupling parameter. This method is applied to simulated ALMA observations with 16, 32 and 50 antennas. As expected this method is found to be more efficient with more antennas and for more compact configurations because the uv-plane coverage is more complete. With 50 antennas in compact configuration it is possible to reduce the amplitude of the inner sidelobes (outer sidelobes) by a factor >6 (>2) compared to natural weighting for ~10 % loss in sensitivity, leading to sidelobes lower than 1.6 % of the main lobe peak value. With 16 antennas only, the method can still be used to reduce the inner sidelobes of a

  5. Directly Estimating Endmembers for Compressive Hyperspectral Images

    PubMed Central

    Xu, Hongwei; Fu, Ning; Qiao, Liyan; Peng, Xiyuan

    2015-01-01

    The large volume of hyperspectral images (HSI) generated creates huge challenges for transmission and storage, making data compression more and more important. Compressive Sensing (CS) is an effective data compression technology that shows that when a signal is sparse in some basis, only a small number of measurements are needed for exact signal recovery. Distributed CS (DCS) takes advantage of both intra- and inter- signal correlations to reduce the number of measurements needed for multichannel-signal recovery. HSI can be observed by the DCS framework to reduce the volume of data significantly. The traditional method for estimating endmembers (spectral information) first recovers the images from the compressive HSI and then estimates endmembers via the recovered images. The recovery step takes considerable time and introduces errors into the estimation step. In this paper, we propose a novel method, by designing a type of coherent measurement matrix, to estimate endmembers directly from the compressively observed HSI data via convex geometry (CG) approaches without recovering the images. Numerical simulations show that the proposed method outperforms the traditional method with better estimation speed and better (or comparable) accuracy in both noisy and noiseless cases. PMID:25905699

  6. Direct ultraviolet imaging and spectroscopy of betelgeuse

    NASA Astrophysics Data System (ADS)

    Dupree, A. K.; Stefanik, R. P.

    2013-05-01

    Direct images of Betelgeuse were obtained over a span of 4 years with the Faint Object Camera on the Hubble Space Telescope. These images reveal the extended ultraviolet continuum emission (~2 times the optical diameter), the varying overall ultraviolet flux levels and a pattern of bright surface continuum features that change in position and appearance over several months or less. Concurrent photometry and radial velocity measures support the model of a pulsating star, first discovered in the ultraviolet from IUE. Spatially resolved HST spectroscopy reveals a larger extention in chromospheric emissions of Mg II as well as the rotation of the supergiant. Changing localized subsonic flows occur in the low chromosphere that can cover a substantial fraction of the stellar disk and may initiate the mass outflow.

  7. MKIDs for Direct Imaging of Exoplanets

    NASA Astrophysics Data System (ADS)

    Mazin, Benjamin A.; Meeker, Seth; Strader, Matthew; Szypryt, Paul; Walter, Alex; Bockstiegel, Clint; Collura, Giulia; Mawet, Dimitri; Jensen-Clem, Rebecca; Guyon, Olivier; Jovanovic, Nemanja; Oppenheimer, Rebecca; Serabyn, Eugene

    2015-12-01

    Microwave Kinetic Inductance Detectors (MKIDs) are single photon counting, energy resolving detectors applicable from the optical through near-IR. MKIDs are especially interesting for exoplanet direct imaging due to their read noise free, high speed, energy resolved near-IR photon counting in reasonably large formats. The first MKID instrument, ARCONS, has been taking data on the Palomar 200” for several years. There are currently two UVOIR MKID instruments fully funded and under construction for direct imaging of planets, DARKNESS for the Palomar coronagraphs and MEC for Subaru’s SCExAO. Operating an MKID camera behind these coronagraphs will allow an effective 2 kHz frame rate with minimal latency, allowing fast real-time nulling of atmospheric speckles. Simulations show this could improve contrast ratios by up to a factor of 100. In this this talk I will discuss the current state of these cameras as well as their expected scientific yield. In particular, MEC with SCExAO on Subaru may be capable of detecting Jupiter analogs in reflected light within the next 2 years.

  8. MKIDs for Direct Imaging of Exoplanets

    NASA Astrophysics Data System (ADS)

    Mazin, B. A.; Eyken, J. v.; Meeker, S. R.; Jensen-Clem, R.; Oppenheimer, B. R.; Guyon, O.

    2014-03-01

    Microwave Kinetic Inductance Detectors, or MKIDs (Mazin et al 2012, 2013), are an emerging superconducting focal plane array technology that enables noise-free single photon counting and low resolution spectrophotometry throughout the optical and near-IR. MKIDs have enormous potential as combined integral field units (IFUs) for science data and focal plane wavefront sensors for coronagraphic direct imaging experiments. Their high speed and lack of read noise enables fast feedback for speckle nulling of atmospheric and quasistatic speckles, and the read noise-free science data cubes can be post-processed with a variety of speckle removal algorithms such as Chromatic Differential Imaging and the Dark Speckle technique. In this presentation we present preliminary performance calculations and designs of the recently funded 10,000 pixel MKID-based DARKNESS camera for the P1640 coronagraph at the Palomar 200 inch, and our plans for SSEC, a similar instrument for Subaru's SCExAO that could potentially image a handful of known RV planets in reflected light.

  9. Archaeology and direct imaging of exoplanets

    NASA Astrophysics Data System (ADS)

    Campbell, John B.

    The search for extraterrestrial technology effectively began 45 years ago with Frank Drake's Project Ozma and a radioastronomy start to the search for extraterrestrial intelligence (SETI). Eventually searches began for possible interstellar probes in stable orbits in the Solar System, as well as for infrared excesses from possible Dyson spheres round Sun-like stars. Whilst the Cold War was still underway, some scientists looked for evidence of nuclear waste dumps and nuclear wars elsewhere in the Milky Way. None of this work was carried out by archaeologists, even though by their very nature archaeologists are experts in the detection of ancient technologies. The technologies being searched for would have been partly ancient in age though advanced in techniques and science. The development of ESA's Darwin and NASA's TPF for detection and imaging of Earth-like exoplanets in our galactic neighbourhood represents an opportunity for the testing of techniques for detecting signatures of technological activities. Ideally, both Darwin and TPF might be able to provide spectroscopic data on the chemistry and biochemistry of the atmospheres of Earth-like exoplanets, and thus to detect some of the signs of life. If this can be accomplished successfully, then in theory evidence for pollution and nuclear accidents and wars should be detectable. Some infrared signatures of ETT on or round exoplanets might be detectable. Direct visual imaging of ETT structures will probably not be feasible till we have extremely powerful interstellar telescopes or actually send orbital craft.

  10. Implementation of a direct-imaging and FX correlator for the BEST-2 array

    NASA Astrophysics Data System (ADS)

    Foster, G.; Hickish, J.; Magro, A.; Price, D.; Zarb Adami, K.

    2014-04-01

    A new digital backend has been developed for the Basic Element for SKA Training II (BEST-2) array at Radiotelescopi di Medicina, INAF-IRA, Italy, which allows concurrent operation of an FX correlator, and a direct-imaging correlator and beamformer. This backend serves as a platform for testing some of the spatial Fourier transform concepts which have been proposed for use in computing correlations on regularly gridded arrays. While spatial Fourier transform-based beamformers have been implemented previously, this is, to our knowledge, the first time a direct-imaging correlator has been deployed on a radio astronomy array. Concurrent observations with the FX and direct-imaging correlator allow for direct comparison between the two architectures. Additionally, we show the potential of the direct-imaging correlator for time-domain astronomy, by passing a subset of beams though a pulsar and transient detection pipeline. These results provide a timely verification for spatial Fourier transform-based instruments that are currently in commissioning. These instruments aim to detect highly redshifted hydrogen from the epoch of reionization and/or to perform wide-field surveys for time-domain studies of the radio sky. We experimentally show the direct-imaging correlator architecture to be a viable solution for correlation and beamforming.

  11. Adaptive optics for directly imaging planetary systems

    NASA Astrophysics Data System (ADS)

    Bailey, Vanessa Perry

    In this dissertation I present the results from five papers (including one in preparation) on giant planets, brown dwarfs, and their environments, as well as on the commissioning and optimization of the Adaptive Optics system for the Large Binocular Telescope Interferometer. The first three Chapters cover direct imaging results on several distantly-orbiting planets and brown dwarf companions. The boundary between giant planets and brown dwarf companions in wide orbits is a blurry one. In Chapter 2, I use 3--5 mum imaging of several brown dwarf companions, combined with mid-infrared photometry for each system to constrain the circum-substellar disks around the brown dwarfs. I then use this information to discuss limits on scattering events versus in situ formation. In Chapters 3 and 4, I present results from an adaptive optics imaging survey for giant planets, where the target stars were selected based on the properties of their circumstellar debris disks. Specifically, we targeted systems with debris disks whose SEDs indicated gaps, clearings, or truncations; these features may possibly be sculpted by planets. I discuss in detail one planet-mass companion discovered as part of this survey, HD 106906 b. At a projected separation of 650 AU and weighing in at 11 Jupiter masses, a companion such as this is not a common outcome of any planet or binary star formation model. In the remaining three Chapters, I discuss pre-commissioning, on-sky results, and planned work on the Large Binocular Telescope Interferometer Adaptive Optics system. Before construction of the LBT AO system was complete, I tested a prototype of LBTI's pyramid wavefront sensor unit at the MMT with synthetically-generated calibration files. I present the methodology and MMT on-sky tests in Chapter 5. In Chapter 6, I present the commissioned performance of LBTIAO. Optical imperfections within LBTI limited the quality of the science images, and I describe a simple method to use the adaptive optics system

  12. Mass Determination Of Directly Imaged Planet Candidates

    NASA Astrophysics Data System (ADS)

    Schmidt, Tobias; Neuhauser, R.; Seifahrt, A.

    2011-09-01

    About 20 sub-stellar companions with large separations (> 50 AU) to their young primary stars and brown dwarfs are confirmed by both common proper motion and late-M / early-L type spectra. The origin and early evolution of these objects is still under debate. While often these sub-stellar companions are regarded as brown dwarfs, they could possibly also be massive planets, the mass estimates are very uncertain so far. They are companions to primary stars or brown dwarfs in young associations and star forming regions like Taurus, Upper Scorpius, the TW Hya association, Beta Pic moving group, TucHor association, Lupus, Ophiuchus, and Chamaeleon, hence their ages and distances are well known, in contrast to free-floating brown dwarfs. Here we present how mass estimates of such young directly imaged companions can be derived, using e.g. evolutionary models, which are however currently almost uncalibrated by direct mass measurements of young objects. An empirical classification by medium-resolution spectroscopy is currently not possible, because a spectral sequence that is taking the lower gravity into account, is not existing. This problem leads to an apparent mismatch between spectra of old field type objects and young low-mass companions at the same effective temperature, hampering a determination of temperature and surface gravity independent from models. We show that from spectra of the objects, using the advantages of light concentration by an AO-assisted integral field spectrograph, temperature, extinction, metallicity and surface gravity can be derived using non-equilibrium radiative transfer atmosphere models as comparison and that this procedure as well allows a mass determination in combination with the luminosities found by the direct observations, as has recently been done by us for several young sub-stellar companions, as e.g. GQ Lup, CT Cha or UScoCTIO 108.

  13. Direct Imaging of Warm Extrasolar Planets

    SciTech Connect

    Macintosh, B

    2005-04-11

    One of the most exciting scientific discoveries in the last decade of the twentieth century was the first detection of planets orbiting a star other than our own. By now more than 130 extrasolar planets have been discovered indirectly, by observing the gravitational effects of the planet on the radial velocity of its parent star. This technique has fundamental limitations: it is most sensitive to planets close to their star, and it determines only a planet's orbital period and a lower limit on the planet's mass. As a result, all the planetary systems found so far are very different from our own--they have giant Jupiter-sized planets orbiting close to their star, where the terrestrial planets are found in our solar system. Such systems have overturned the conventional paradigm of planet formation, but have no room in them for habitable Earth-like planets. A powerful complement to radial velocity detections of extrasolar planets will be direct imaging--seeing photons from the planet itself. Such a detection would allow photometric measurements to determine the temperature and radius of a planet. Also, direct detection is most sensitive to planets in wide orbits, and hence more capable of seeing solar systems resembling our own, since a giant planet in a wide orbit does not preclude the presence of an Earth-like planet closer to the star. Direct detection, however, is extremely challenging. Jupiter is roughly a billion times fainter than our sun. Two techniques allowed us to overcome this formidable contrast and attempt to see giant planets directly. The first is adaptive optics (AO) which allows giant earth-based telescopes, such as the 10 meter W.M. Keck telescope, to partially overcome the blurring effects of atmospheric turbulence. The second is looking for young planets: by searching in the infrared for companions to young stars, we can see thermal emission from planets that are still warm with the heat of their formation. Together with a UCLA team that leads the

  14. Image fusion using bi-directional similarity

    NASA Astrophysics Data System (ADS)

    Bai, Chunshan; Luo, Xiaoyan

    2015-05-01

    Infrared images are widely used in the practical applications to capture abundant information. However, it is still challenging to enhance the infrared image by the visual image. In this paper, we propose an effective method using bidirectional similarity. In the proposed method, we aim to find an optimal solution from many feasible solutions without introducing intermediate image. We employ some priori constraints to meet the requirements of image fusion which can be detailed to preserve both good characteristics in the infrared image and spatial information in the visual image. In the iterative step, we use the matrix with the square of the difference between images to integrate the image holding most information. We call this matrix the bidirectional similarity distance. By the bidirectional similarity distance, we can get the transitive images. Then, we fuse the images according to the weight. Experimental results show that, compared to the traditional image fusion algorithm, fusion images from bidirectional similarity fusion algorithm have greatly improved in the subjective vision, entropy, structural similarity index measurement. We believe that the proposed scheme can have a wide applications.

  15. Di-tert-butylsilylene-directed alpha-selective synthesis of 4-methylumbelliferyl T-antigen.

    PubMed

    Imamura, Akihiro; Ando, Hiromune; Ishida, Hideharu; Kiso, Makoto

    2005-09-29

    [reaction: see text] We have succeeded in the facile synthesis of 4-methylumbelliferyl T-antigen as a substrate for endo-alpha-N-acetylgalactosaminidase by exploiting the combination of the di-tert-butylsilylene effect and the Mitsunobu reaction. PMID:16178547

  16. Confocal imaging of transmembrane voltage by SEER of di-8-ANEPPS.

    PubMed

    Manno, Carlo; Figueroa, Lourdes; Fitts, Robert; Ríos, Eduardo

    2013-03-01

    Imaging, optical mapping, and optical multisite recording of transmembrane potential (V(m)) are essential for studying excitable cells and systems. The naphthylstyryl voltage-sensitive dyes, including di-8-ANEPPS, shift both their fluorescence excitation and emission spectra upon changes in V(m). Accordingly, they have been used for monitoring V(m) in nonratioing and both emission and excitation ratioing modes. Their changes in fluorescence are usually much less than 10% per 100 mV. Conventional ratioing increases sensitivity to between 3 and 15% per 100 mV. Low sensitivity limits the value of these dyes, especially when imaged with low light systems like confocal scanners. Here we demonstrate the improvement afforded by shifted excitation and emission ratioing (SEER) as applied to imaging membrane potential in flexor digitorum brevis muscle fibers of adult mice. SEER--the ratioing of two images of fluorescence, obtained with different excitation wavelengths in different emission bands-was implemented in two commercial confocal systems. A conventional pinhole scanner, affording optimal setting of emission bands but less than ideal excitation wavelengths, achieved a sensitivity of up to 27% per 100 mV, nearly doubling the value found by conventional ratioing of the same data. A better pair of excitation lights should increase the sensitivity further, to 35% per 100 mV. The maximum acquisition rate with this system was 1 kHz. A fast "slit scanner" increased the effective rate to 8 kHz, but sensitivity was lower. In its high-sensitivity implementation, the technique demonstrated progressive deterioration of action potentials upon fatiguing tetani induced by stimulation patterns at >40 Hz, thereby identifying action potential decay as a contributor to fatigue onset. Using the fast implementation, we could image for the first time an action potential simultaneously at multiple locations along the t-tubule system. These images resolved the radially varying lag associated

  17. Confocal imaging of transmembrane voltage by SEER of di-8-ANEPPS

    PubMed Central

    Manno, Carlo; Figueroa, Lourdes; Fitts, Robert

    2013-01-01

    Imaging, optical mapping, and optical multisite recording of transmembrane potential (Vm) are essential for studying excitable cells and systems. The naphthylstyryl voltage-sensitive dyes, including di-8-ANEPPS, shift both their fluorescence excitation and emission spectra upon changes in Vm. Accordingly, they have been used for monitoring Vm in nonratioing and both emission and excitation ratioing modes. Their changes in fluorescence are usually much less than 10% per 100 mV. Conventional ratioing increases sensitivity to between 3 and 15% per 100 mV. Low sensitivity limits the value of these dyes, especially when imaged with low light systems like confocal scanners. Here we demonstrate the improvement afforded by shifted excitation and emission ratioing (SEER) as applied to imaging membrane potential in flexor digitorum brevis muscle fibers of adult mice. SEER—the ratioing of two images of fluorescence, obtained with different excitation wavelengths in different emission bands—was implemented in two commercial confocal systems. A conventional pinhole scanner, affording optimal setting of emission bands but less than ideal excitation wavelengths, achieved a sensitivity of up to 27% per 100 mV, nearly doubling the value found by conventional ratioing of the same data. A better pair of excitation lights should increase the sensitivity further, to 35% per 100 mV. The maximum acquisition rate with this system was 1 kHz. A fast “slit scanner” increased the effective rate to 8 kHz, but sensitivity was lower. In its high-sensitivity implementation, the technique demonstrated progressive deterioration of action potentials upon fatiguing tetani induced by stimulation patterns at >40 Hz, thereby identifying action potential decay as a contributor to fatigue onset. Using the fast implementation, we could image for the first time an action potential simultaneously at multiple locations along the t-tubule system. These images resolved the radially varying lag

  18. Direct Estimation of Kinetic Parametric Images for Dynamic PET

    PubMed Central

    Wang, Guobao; Qi, Jinyi

    2013-01-01

    Dynamic positron emission tomography (PET) can monitor spatiotemporal distribution of radiotracer in vivo. The spatiotemporal information can be used to estimate parametric images of radiotracer kinetics that are of physiological and biochemical interests. Direct estimation of parametric images from raw projection data allows accurate noise modeling and has been shown to offer better image quality than conventional indirect methods, which reconstruct a sequence of PET images first and then perform tracer kinetic modeling pixel-by-pixel. Direct reconstruction of parametric images has gained increasing interests with the advances in computing hardware. Many direct reconstruction algorithms have been developed for different kinetic models. In this paper we review the recent progress in the development of direct reconstruction algorithms for parametric image estimation. Algorithms for linear and nonlinear kinetic models are described and their properties are discussed. PMID:24396500

  19. Mueller matrix three-dimensional directional imaging of collagen fibers.

    PubMed

    Ellingsen, Pål Gunnar; Aas, Lars Martin Sandvik; Hagen, Vegard Stenhjem; Kumar, Rajesh; Lilledahl, Magnus Borstad; Kildemo, Morten

    2014-02-01

    A method for measuring three-dimensional (3-D) direction images of collagen fibers in biological tissue is presented. Images of the 3-D directions are derived from the measured transmission Mueller matrix images (MMIs), acquired at different incidence angles, by taking advantage of the form birefringence of the collagen fibers. The MMIs are decomposed using the recently developed differential decomposition, which is more suited to biological tissue samples than the common polar decomposition method. Validation of the 3-D direction images was performed by comparing them with images from second-harmonic generation microscopy. The comparison found a good agreement between the two methods. It is envisaged that 3-D directional imaging could become a useful tool for understanding the collagen framework for fibers smaller than the diffraction limit. PMID:24503637

  20. Geometric direct search algorithms for image registration.

    PubMed

    Lee, Seok; Choi, Minseok; Kim, Hyungmin; Park, Frank Chongwoo

    2007-09-01

    A widely used approach to image registration involves finding the general linear transformation that maximizes the mutual information between two images, with the transformation being rigid-body [i.e., belonging to SE(3)] or volume-preserving [i.e., belonging to SL(3)]. In this paper, we present coordinate-invariant, geometric versions of the Nelder-Mead optimization algorithm on the groups SL(3), SE(3), and their various subgroups, that are applicable to a wide class of image registration problems. Because the algorithms respect the geometric structure of the underlying groups, they are numerically more stable, and exhibit better convergence properties than existing local coordinate-based algorithms. Experimental results demonstrate the improved convergence properties of our geometric algorithms. PMID:17784595

  1. Mars Rover imaging systems and directional filtering

    NASA Technical Reports Server (NTRS)

    Wang, Paul P.

    1989-01-01

    Computer literature searches were carried out at Duke University and NASA Langley Research Center. The purpose is to enhance personal knowledge based on the technical problems of pattern recognition and image understanding which must be solved for the Mars Rover and Sample Return Mission. Intensive study effort of a large collection of relevant literature resulted in a compilation of all important documents in one place. Furthermore, the documents are being classified into: Mars Rover; computer vision (theory); imaging systems; pattern recognition methodologies; and other smart techniques (AI, neural networks, fuzzy logic, etc).

  2. Object silhouettes and surface directions through stereo matching image processing

    NASA Astrophysics Data System (ADS)

    Akiyama, Akira; Kumagai, Hideo

    2015-09-01

    We have studied the object silhouettes and surface direction through the stereo matching image processing to recognize the position, size and surface direction of the object. For this study we construct the pixel number change distribution of the HSI color component level, the binary component level image by the standard deviation threshold, the 4 directional pixels connectivity filter, the surface elements correspondence by the stereo matching and the projection rule relation. We note that the HSI color component level change tendency of the object image near the focus position is more stable than the HSI color component level change tendency of the object image over the unfocused range. We use the HSI color component level images near the fine focused position to extract the object silhouette. We extract the object silhouette properly. We find the surface direction of the object by the pixel numbers of the correspondence surface areas and the projection cosine rule after the stereo matching image processing by the characteristic areas and the synthesized colors. The epipolar geometry is used in this study because a pair of imager is arranged on the same epipolar plane. The surface direction detection results in the proper angle calculation. The construction of the object silhouettes and the surface direction detection of the object are realized.

  3. Direct infrared imaging of VB 8

    NASA Technical Reports Server (NTRS)

    Skrutskie, M. F.; Forret, W. J.; Shure, M. A.

    1987-01-01

    Near-infrared images of VB 8 taken at K (2.2 microns) and L-prime (3.75 microns) during a period of good seeing at the IRTF show no evidence of the brown dwarf companion reported by McCarthy et al. (1985). Any companion 1.0 arcsec away from the primary must be at least 4 mag fainter than the primary at K and 3 mag fainter at L-prime in order to escape detection. A faint nebula centered on the star with scattering properties similar to a nebula detected near another main-sequence M star, Lalande 21185 (reported by McCarthy in 1986), may account for the extended emission detected by speckle observations.

  4. Compressive sensing for direct millimeter-wave holographic imaging.

    PubMed

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

    2015-04-10

    Direct millimeter-wave (MMW) holographic imaging, which provides both the amplitude and phase information by using the heterodyne mixing technique, is considered a powerful tool for personnel security surveillance. However, MWW imaging systems usually suffer from the problem of high cost or relatively long data acquisition periods for array or single-pixel systems. In this paper, compressive sensing (CS), which aims at sparse sampling, is extended to direct MMW holographic imaging for reducing the number of antenna units or the data acquisition time. First, following the scalar diffraction theory, an exact derivation of the direct MMW holographic reconstruction is presented. Then, CS reconstruction strategies for complex-valued MMW images are introduced based on the derived reconstruction formula. To pursue the applicability for near-field MMW imaging and more complicated imaging targets, three sparsity bases, including total variance, wavelet, and curvelet, are evaluated for the CS reconstruction of MMW images. We also discuss different sampling patterns for single-pixel, linear array and two-dimensional array MMW imaging systems. Both simulations and experiments demonstrate the feasibility of recovering MMW images from measurements at 1/2 or even 1/4 of the Nyquist rate. PMID:25967314

  5. OH radical imaging in a DI diesel engine and the structure of the early diffusion flame

    SciTech Connect

    Dec, J.E.; Coy, E.B.

    1996-03-01

    Laser-sheet imaging studies have considerably advanced our understanding of diesel combustion; however, the location and nature of the flame zones within the combusting fuel jet have been largely unstudied. To address this issue, planar laser-induced fluorescence (PLIF) imaging of the OH radical has been applied to the reacting fuel jet of a direct-injection diesel engine of the ``heavy-duty`` size class, modified for optical access. An Nd:YAG-based laser system was used to pump the overlapping Q{sub 1}9 and Q{sub 2}8 lines of the (1,0) band of the A{yields}X transition at 284.01 nm, while the fluorescent emission from both the (0,O) and (1, I) bands (308 to 320 nm) was imaged with an intensified video camera. This scheme allowed rejection of elastically scattered laser light, PAH fluorescence, and laser-induced incandescence. OH PLIF is shown to be an excellent diagnostic for diesel diffusion flames. The signal is strong, and it is confined to a narrow region about the flame front because the threebody recombination reactions that reduce high flame-front OH concentrations to equilibrium levels occur rapidly at diesel pressures. No signal was evident in the fuel-rich premixed flame regions where calculations and burner experiments indicate that OH concentrations will be below detectable limits. Temporal sequences of OH PLIF images are presented showing the onset and development of the early diffusion flame up to the time that soot obscures the images. These images show that the diffusion flame develops around the periphery of the-downstream portion of the reacting fuel jet about half way through the premixed burn spike. Although affected by turbulence, the diffusion flame remains at the jet periphery for the rest of the imaged sequence.

  6. Image deblurring using the direction dependence of camera resolution

    NASA Astrophysics Data System (ADS)

    Hirai, Yukio; Yoshikawa, Hiroyasu; Shimizu, Masayoshi

    2013-03-01

    The blurring that occurs in the lens of a camera has a tendency to further degrade in areas away from the on-axis of the image. In addition, the degradation of the blurred image in an off-axis area exhibits directional dependence. Conventional methods have been known to use the Wiener filter or the Richardson-Lucy algorithm to mitigate the problem. These methods use the pre-defined point spread function (PSF) in the restoration process, thereby preventing an increase in the noise elements. However, the nonuniform degradation that depends on the direction is not improved even though the edges are emphasized by these conventional methods. In this paper, we analyze the directional dependence of resolution based on the modeling of an optical system using a blurred image. We propose a novel image deblurring method that employs a reverse filter based on optimizing the directional dependence coefficients of the regularization term in the maximum a posterior probability (MAP) algorithm. We have improved the directional dependence of resolution by optimizing the weight coefficients of the direction in which the resolution is degraded.

  7. Direction Dependent Effects In Widefield Wideband Full Stokes Radio Imaging

    NASA Astrophysics Data System (ADS)

    Jagannathan, Preshanth; Bhatnagar, Sanjay; Rau, Urvashi; Taylor, Russ

    2015-01-01

    Synthesis imaging in radio astronomy is affected by instrumental and atmospheric effects which introduce direction dependent gains.The antenna power pattern varies both as a function of time and frequency. The broad band time varying nature of the antenna power pattern when not corrected leads to gross errors in full stokes imaging and flux estimation. In this poster we explore the errors that arise in image deconvolution while not accounting for the time and frequency dependence of the antenna power pattern. Simulations were conducted with the wideband full stokes power pattern of the Very Large Array(VLA) antennas to demonstrate the level of errors arising from direction-dependent gains. Our estimate is that these errors will be significant in wide-band full-pol mosaic imaging as well and algorithms to correct these errors will be crucial for many up-coming large area surveys (e.g. VLASS)

  8. Direct extraction of topographic features from gray scale haracter images

    SciTech Connect

    Seong-Whan Lee; Young Joon Kim

    1994-12-31

    Optical character recognition (OCR) traditionally applies to binary-valued imagery although text is always scanned and stored in gray scale. However, binarization of multivalued image may remove important topological information from characters and introduce noise to character background. In order to avoid this problem, it is indispensable to develop a method which can minimize the information loss due to binarization by extracting features directly from gray scale character images. In this paper, we propose a new method for the direct extraction of topographic features from gray scale character images. By comparing the proposed method with the Wang and Pavlidis`s method we realized that the proposed method enhanced the performance of topographic feature extraction by computing the directions of principal curvature efficiently and prevented the extraction of unnecessary features. We also show that the proposed method is very effective for gray scale skeletonization compared to Levi and Montanari`s method.

  9. Hypertelescopes: The Challenge of Direct Imaging at High Resolution

    NASA Astrophysics Data System (ADS)

    Labeyrie, A.

    2013-03-01

    Sparse optical interferometric arrays of many apertures can produce direct images in the densified-pupil mode, also called "hypertelescope" mode. Pending the introduction of adaptive optics for cophasing, indirect images can also be reconstructed with speckle imaging techniques. But adaptive phasing is preferable, when a sufficiently bright guide star is available. Several wave sensing techniques, by-products of those used on monolithic telescopes for some of them, are potentially usable. For cophased direct images of very faint sources in the absence of a natural guide star, a modified form of the Laser Guide Star techniques demonstrated on conventional and segmented telescopes is described. Preliminary testing in laboratory suggests further investigation. Recorded images, assumed co-phased, are also improvable post-detection with optical aperture-synthesis techniques such as Earth rotation synthesis, where data from successive exposures are combined incoherently. Nevertheless, the gain becomes modest if hundreds of sub-apertures are used. Image deconvolution techniques are also applicable, if suitably modified as demonstrated by Aime et al. (2012), and Mary (2012). Their modified deconvolution algorithms can extend the Direct Imaging Field (also called Clean Field) of hypertelescopes. More sub-apertures at given collecting area, implying that their size is reduced, improve the direct-imaging performance. The predictable trend thus favors systems combining hundreds of sub-apertures of modest size, if workable designs can be evolved. One such design, the "Ubaye Hypertelescope" entering the initial testing phase in the southern Alps, has a fixed spherical meta-mirror with a 57 m effective aperture, expandable to 200 m. Preliminary results suggest that larger versions, whether spherical or active paraboloidal, can reach a kilometric aperture size at terrestrial sites having a suitable concave topography. In space, hypertelescope meta-apertures spanning up to 100 000

  10. Direct Sub-Angstrom Imaging of a Crystal Lattice

    SciTech Connect

    Nellist, Peter D.; Chisholm, Matthew F; Dellby, N.; Krivanek, O. L.; Murfitt, M. F.; Szilagyi, Z. S.; Lupini, Andrew R; Borisevich, Albina Y; Sides, Jr., William H.; Pennycook, Stephen J

    2004-01-01

    Despite the use of electrons with wavelengths of just a few picometers, spatial resolution in a transmission electron microscope (TEM) has been limited by spherical aberration to typically around 0.15 nanometer. Individual atomic columns in a crystalline lattice can therefore only be imaged for a few low-order orientations, limiting the range of defects that can be imaged at atomic resolution. The recent development of spherical aberration correctors for transmission electron microscopy allows this limit to be overcome. We present direct images from an aberration-corrected scanning TEM that resolve a lattice in which the atomic columns are separated by less than 0.1 nanometer.

  11. VIDA: A Direct Spectro-Imager for the VLTI

    NASA Astrophysics Data System (ADS)

    Lardièere, Olivier; Schneider, Jean

    In order to exploit the unique full forthcoming VLTI infrastructure (4 to 8 telescopes with AO and cophasing system), we propose VIDA, a near-IR direct imaging instrument using an all-to-one beam combiner and single-mode fibers. The pupil densification technique is used to concentrate all the flux in the field accessible by the VLTI array in one observation. This optimal use of photons provides more luminous and contrasted snapshot images than the Fizeau mode. Thanks to its snapshot capabilities ant its better sensitivity, this innovative instrument should open new investigation fields for the VLTI, as faint extragalactic sources studying and hot jupiters coronagraphic imaging

  12. Dosimetry and image quality assessment in a direct radiography system

    PubMed Central

    Oliveira, Bruno Beraldo; de Oliveira, Marcio Alves; Paixão, Lucas; Teixeira, Maria Helena Araújo; Nogueira, Maria do Socorro

    2014-01-01

    Objective To evaluate the mean glandular dose with a solid state detector and the image quality in a direct radiography system, utilizing phantoms. Materials and Methods Irradiations were performed with automatic exposure control and polymethyl methacrylate slabs with different thicknesses to calculate glandular dose values. The image quality was evaluated by means of the structures visualized on the images of the phantoms. Results Considering the uncertainty of the measurements, the mean glandular dose results are in agreement with the values provided by the equipment and with internationally adopted reference levels. Results obtained from images of the phantoms were in agreement with the reference values. Conclusion The present study contributes to verify the equipment conformity as regards dose values and image quality. PMID:25741119

  13. VIP: Vortex Image Processing pipeline for high-contrast direct imaging of exoplanets

    NASA Astrophysics Data System (ADS)

    Gomez Gonzalez, Carlos Alberto; Wertz, Olivier; Christiaens, Valentin; Absil, Olivier; Mawet, Dimitri

    2016-03-01

    VIP (Vortex Image Processing pipeline) provides pre- and post-processing algorithms for high-contrast direct imaging of exoplanets. Written in Python, VIP provides a very flexible framework for data exploration and image processing and supports high-contrast imaging observational techniques, including angular, reference-star and multi-spectral differential imaging. Several post-processing algorithms for PSF subtraction based on principal component analysis are available as well as the LLSG (Local Low-rank plus Sparse plus Gaussian-noise decomposition) algorithm for angular differential imaging. VIP also implements the negative fake companion technique coupled with MCMC sampling for rigorous estimation of the flux and position of potential companions.

  14. Retinex Image Processing: Improved Fidelity To Direct Visual Observation

    NASA Technical Reports Server (NTRS)

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

    1996-01-01

    Recorded color images differ from direct human viewing by the lack of dynamic range compression and color constancy. Research is summarized which develops the center/surround retinex concept originated by Edwin Land through a single scale design to a multi-scale design with color restoration (MSRCR). The MSRCR synthesizes dynamic range compression, color constancy, and color rendition and, thereby, approaches fidelity to direct observation.

  15. Detectability of Tidally Heated Exomoons Using Direct Imaging Techniques

    NASA Astrophysics Data System (ADS)

    Peters, Mary Anne; Turner, E. L.

    2013-01-01

    We determine the capability of ground and space-based observatories, both existing and planned, to directly image tidally heated exomoons orbiting exoplanets. Tidally heated exomoons, or THEMs, can conceivably be much more luminous than their host exoplanet and as little as 1000 times dimmer than the system's primary star. Tidal forces can heat THEMs at arbitrarily large angular separations from the host star, in both young and old star systems, to temperatures of hundreds or even thousands of degrees Kelvin. THEMs may thus be far easier targets for direct imaging studies than giant exoplanets which must be both young and at a large projected angular separation from their host star to be imaged with existing high contrast instrumentation. Current instruments are capable of detecting nearby THEMs with Teff ≥ 600K and R ≥ Rearth in K-band. Future mid-infrared space telescopes, such as JWST and SPICA, will be capable of directly imaging THEMs around ~25 nearby stars with Teff ≥ 300K and R≥Rearth orbiting at angular separations ≥ 12AU at a 5σ confidence level in a 10,000 second integration. It is feasible that previously imaged exoplanets are actually THEMs or blends of such objects with hot young planets; we speculate that Fomalhaut b could be such a case. If THEMs exist and are common (i.e., nearby), it may be far easier to directly image a THEM with surface conditions that allow for liquid water than it will be to image an Earth-like planet in the classical Habitable Zone of its primary star.

  16. Direct trabecular meshwork imaging in porcine eyes through multiphoton gonioscopy

    NASA Astrophysics Data System (ADS)

    Masihzadeh, Omid; Ammar, David A.; Kahook, Malik Y.; Gibson, Emily A.; Lei, Tim C.

    2013-03-01

    The development of technologies to characterize the ocular aqueous outflow system (AOS) is important for the understanding of the pathophysiology of glaucoma. Multiphoton microscopy (MPM) offers the advantage of high-resolution, label-free imaging with intrinsic image contrast because the emitted signals result from the specific biomolecular content of the tissue. Previous attempts to use MPM to image the murine irido-corneal region directly through the sclera have suffered from degradation in image resolution due to scattering of the focused laser light. As a result, transscleral MPM has limited ability to observe fine structures in the AOS. In this work, the porcine irido-corneal angle was successfully imaged through the transparent cornea using a gonioscopic lens to circumvent the highly scattering scleral tissue. The resulting high-resolution images allowed the detailed structures in the trabecular meshwork (TM) to be observed. Multimodal imaging by two-photon autofluorescence and second harmonic generation allowed visualization of different features in the TM without labels and without disruption of the TM or surrounding tissues. MPM gonioscopy is a promising noninvasive imaging tool for high-resolution studies of the AOS, and research continues to explore the potential for future clinical applications in humans.

  17. Direct laser additive fabrication system with image feedback control

    DOEpatents

    Griffith, Michelle L.; Hofmeister, William H.; Knorovsky, Gerald A.; MacCallum, Danny O.; Schlienger, M. Eric; Smugeresky, John E.

    2002-01-01

    A closed-loop, feedback-controlled direct laser fabrication system is disclosed. The feedback refers to the actual growth conditions obtained by real-time analysis of thermal radiation images. The resulting system can fabricate components with severalfold improvement in dimensional tolerances and surface finish.

  18. Method to directly radiolabel antibodies for diagnostic imaging and therapy

    SciTech Connect

    Thakur, M.L.

    1991-04-30

    This patent describes a method for directly labeling proteins with radionuclides for use in diagnostic imaging and therapy. It comprises: the steps of incubating a protein-containing solution with a solution of sodium ascorbate; adding a required quantity of reduced radionuclide to the incubated protein-containing solution and incubating.

  19. Three-dimensional imaging for indirect-direct bonding.

    PubMed

    El-Timamy, Ahmed M; El-Sharaby, Fouad A; Eid, Faten H; Mostafa, Yehya A

    2016-06-01

    The aim of this article is to introduce a new concept of bracket positioning with special consideration to root axes. Cone-beam computed tomography imaging and computer-aided manufacturing were used to produce stereolithographic trays for indirect-direct bonding. PMID:27242004

  20. Data Images and Other Graphical Displays for Directional Data

    NASA Technical Reports Server (NTRS)

    Morphet, Bill; Symanzik, Juergen

    2005-01-01

    Vectors, axes, and periodic phenomena have direction. Directional variation can be expressed as points on a unit circle and is the subject of circular statistics, a relatively new application of statistics. An overview of existing methods for the display of directional data is given. The data image for linear variables is reviewed, then extended to directional variables by displaying direction using a color scale composed of a sequence of four or more color gradients with continuity between sequences and ordered intuitively in a color wheel such that the color of the 0deg angle is the same as the color of the 360deg angle. Cross over, which arose in automating the summarization of historical wind data, and color discontinuity resulting from the use a single color gradient in computational fluid dynamics visualization are eliminated. The new method provides for simultaneous resolution of detail on a small scale and overall structure on a large scale. Example circular data images are given of a global view of average wind direction of El Nino periods, computed rocket motor internal combustion flow, a global view of direction of the horizontal component of earth's main magnetic field on 9/15/2004, and Space Shuttle solid rocket motor nozzle vectoring.

  1. DIRECT IMAGING CONSTRAINTS ON THE PUTATIVE EXOPLANET 14 Her C

    SciTech Connect

    Rodigas, Timothy J.; Males, Jared R.; Hinz, Philip M.; Knox, Russell P.; Mamajek, Eric E.

    2011-05-01

    We present results of deep direct imaging of the radial velocity (RV) planet-host star 14 Her (=GJ 614, HD 145675), obtained in the L' band with the Clio-2 camera and the MMT adaptive optics system. This star has one confirmed planet and an unconfirmed outer companion, suggested by residuals in the RV data. The orbital parameters of the unconfirmed object are not well constrained since many mass/semimajor axis configurations can fit the available data. The star has been directly imaged several times, but none of the campaigns has ruled out sub-stellar companions. With {approx}2.5 hr of integration, we rule out at 5{sigma} confidence {approx}>18 M{sub J} companions beyond {approx}25 AU, based on the Baraffe et al. COND mass-luminosity models. Combining our detection limits with fits to the RV data and analytic dynamical analysis, we constrain the orbital parameters of 14 Her c to be 3 {approx}< m/M{sub J} {approx}<42, 7 {approx}< a/AU {approx}<25, and e {approx}< 0.5. A wealth of information can be obtained from RV/direct imaging overlap, especially with deep imaging as this work shows. The collaboration between RV and direct imaging will become more important in the coming years as the phase space probed by each technique converges. Future studies involving RV/imaging overlap should be sure to consider the effects of a potential planet's projected separation, as quoting limits assuming face-on orientation will be misleading.

  2. Fuel Cross Leak of Direct Di-methyl-ether Fuel Cell

    NASA Astrophysics Data System (ADS)

    Tsutsumi, Yasuyuki; Nakano, Yasuhiro; Haraguchi, Tadao

    Fuel cross leak through a polymer electrolyte membrane of the direct dimethyl ether fuel cell (DDFC) was investigated and was found to be approximately one-tenth that of the direct methanol fuel cell (DMFC). Three phenomena known to appear in the DMFC were also observed in the DDFC. These were (1) fuel cross leak due to the diffusion which increases with the fuel concentration on an open circuit condition, (2) electro-osmotic cross leak, which increases with the current density and fuel concentration, and (3) decrease of fuel cross leak with the increase of the current density due to fuel consumption at low fuel concentration. The decreased fuel cross leak realized by using Nafion ®117 as a membrane and the low fuel concentration of 11% resulted in an increase of the Farady efficiency of the DDFC of up to 90% at a current density of 80mA/cm2. The CO2 quantity at the anode outlet of the operating DDFC was slightly less than 2 mol per 12 protons, as estimated from an electrochemical reaction on the anode. The CO2 quantity at the cathode outlet was also investigated. The CO2 cross leak increased with current density at every CO2 concentration and the diffusion appeared to be the dominant phenomenon of the CO2 cross leak.

  3. Direct imaging of multiple planets orbiting the star HR 8799

    SciTech Connect

    Marois, C; Macintosh, B; Barman, T; Zuckerman, B; Song, I; Patience, J; Lafreniere, D; Doyon, R

    2008-10-14

    Direct imaging of exoplanetary systems is a powerful technique that can reveal Jupiter-like planets in wide orbits, can enable detailed characterization of planetary atmospheres, and is a key step towards imaging Earth-like planets. Imaging detections are challenging due to the combined effect of small angular separation and large luminosity contrast between a planet and its host star. High-contrast observations with the Keck and Gemini telescopes have revealed three planets orbiting the star HR 8799, with projected separations of 24, 38, and 68 astronomical units. Multi-epoch data show counter-clockwise orbital motion for all three imaged planets. The low luminosity of the companions and the estimated age of the system imply planetary masses between 5 and 13 times that of Jupiter. This system resembles a scaled-up version of the outer portion of our Solar System.

  4. Statistical length measurement method by direct imaging of carbon nanotubes.

    PubMed

    Bengio, E Amram; Tsentalovich, Dmitri E; Behabtu, Natnael; Kleinerman, Olga; Kesselman, Ellina; Schmidt, Judith; Talmon, Yeshayahu; Pasquali, Matteo

    2014-05-14

    The influence of carbon nanotube (CNT) length on their macroscopic properties requires an accurate methodology for CNT length measurement. So far, existing techniques are limited to short (less than a few micrometers) CNTs and sample preparation methods that bias the measured values. Here, we show that the average length of carbon nanotubes (CNTs) can be measured by cryogenic transmission electron microscopy (cryo-TEM) of CNTs in chlorosulfonic acid. The method consists of dissolving at low concentration CNTs in chlorosulfonic acid (a true solvent), imaging the individual CNTs by cryo-TEM, and processing and analyzing the images to determine CNT length. By measuring the total CNT contour length and number of CNT ends in each image, and by applying statistical analysis, we extend the method to cases where each CNT is long enough to span many cryo-TEM images, making the direct length measurement of an entire CNT impractical. Hence, this new technique can be used effectively to estimate samples in a wide range of CNT lengths, although we find that cryo-TEM imaging may bias the measurement towards longer CNTs, which are easier to detect. Our statistical method is also applied to AFM images of CNTs to show that, by using only a few AFM images, it yields estimates that are consistent with literature techniques, based on individually measuring a higher number of CNTs. PMID:24773046

  5. Di-tert-butylsilylene-directed alpha-selective synthesis of p-nitrophenyl T-antigen analogues.

    PubMed

    Sato, Tetsuro; Imamura, Akihiro; Ando, Hiromune; Ishida, Hideharu; Kiso, Makoto

    2009-01-01

    Seven analogues of p-nitrophenyl T-antigen [Galbeta(1-->3)GalNAcalpha(1-->O)PNP] have been synthesized as potential substrates for elucidation of the substrate specificity of endo-alpha-N-acetylgalactosaminidase. These compounds, which are commercially unavailable, include: GlcNAcbeta(1-->3){GlcNAcbeta(1-->6)}GalNAcalpha(1-->O)PNP [core 4 type], GalNAcalpha(1-->3)GalNAcalpha(1-->O)PNP [core 5 type], GlcNAcbeta(1-->6)GalNAcalpha(1-->O)PNP [core 6 type], GalNAcalpha(1-->6)GalNAcalpha(1-->O)PNP [core 7 type], Galalpha(1-->3)GalNAcalpha(1-->O)PNP [core 8 type], Glcbeta(1-->3)GalNAcalpha(1-->O)PNP and GalNAcbeta(1-->3)GalNAcalpha(1-->O)PNP. The assembly of these synthetic probes was accomplished efficiently, based on di-tert-butylsilylene(DTBS)-directed alpha-galactosylation as a key reaction. PMID:18709455

  6. A direct screen for c-di-GMP modulators reveals a Salmonella Typhimurium periplasmic ʟ-arginine-sensing pathway.

    PubMed

    Mills, Erez; Petersen, Erik; Kulasekara, Bridget R; Miller, Samuel I

    2015-06-01

    Cyclic-di-GMP (c-di-GMP) is a bacterial second messenger that transduces internal and external signals and regulates bacterial motility and biofilm formation. Some organisms encode more than 100 c-di-GMP-modulating enzymes, but only for a few has a signal been defined that modulates their activity. We developed and applied a high-throughput, real-time flow cytometry method that uses a fluorescence resonance energy transfer (FRET)-based biosensor of free c-di-GMP to screen for signals that modulate its concentration within Salmonella Typhimurium. We identified multiple compounds, including glucose, N-acetyl-d-glucosamine, salicylic acid, and ʟ-arginine, that modulated the FRET signal and therefore the free c-di-GMP concentration. By screening a library of mutants, we identified proteins required for the c-di-GMP response to each compound. Furthermore, low micromolar concentrations of ʟ-arginine induced a rapid translation-independent increase in c-di-GMP concentrations and c-di-GMP-dependent cellulose synthesis, responses that required the regulatory periplasmic domain of the diguanylate cyclase STM1987. ʟ-Arginine signaling also required the periplasmic putative ʟ-arginine-binding protein ArtI, implying that ʟ-arginine sensing occurred in the periplasm. Among the 20 commonly used amino acids, S. Typhimurium specifically responded to ʟ-arginine with an increase in c-di-GMP, suggesting that ʟ-arginine may serve as a signal during S. Typhimurium infection. Our results demonstrate that a second-messenger biosensor can be used to identify environmental signals and define pathways that alter microbial behavior. PMID:26060330

  7. Guided Adaptive Image Smoothing via Directional Anisotropic Structure Measurement.

    PubMed

    Zang, Yu; Huang, Hua; Zhang, Lei

    2015-09-01

    Image smoothing prefers a good metric to identify dominant structures from textures adaptive of intensity contrast. In this paper, we drop on a novel directional anisotropic structure measurement (DASM) toward adaptive image smoothing. With observations on psychological perception regarding anisotropy, non-periodicity and local directionality, DASM can well characterize structures and textures independent on their contrast scales. By using such measurement as constraint, we design a guided adaptive image smoothing scheme by improving extrema localization and envelopes construction in a structure-aware manner. Our approach can well suppresses the staircase-like artifacts and blur of structures that appear in previous methods, which better suits structure-preserving image smoothing task. The algorithm is performed on a space-filling curve as the reduced domain, so it is very fast and much easy to implement in practice. We make comprehensive comparisons with previous state-of-the-art methods for a variety of applications. Experimental results demonstrate the merit using our DASM as metric to identify structures, and the effectiveness and efficiency of our adaptive image smoothing approach to produce commendable results. PMID:26357284

  8. Direct imaging of nanoscale magnetic interactions in minerals

    PubMed Central

    Harrison, Richard J.; Dunin-Borkowski, Rafal E.; Putnis, Andrew

    2002-01-01

    The magnetic microstructure of a natural, finely exsolved intergrowth of submicron magnetite blocks in an ulvöspinel matrix is characterized by using off-axis electron holography in the transmission electron microscope. Single-domain and vortex states in individual blocks, as well as magnetostatic interaction fields between them, are imaged at a spatial resolution approaching the nanometer scale. The images reveal an extremely complicated magnetic structure dominated by the shapes of the blocks and magnetostatic interactions. Magnetic superstates, in which clusters of magnetite blocks act collectively to form vortex and multidomain states that have zero net magnetization, are observed directly. PMID:12482930

  9. ON THE DIRECT IMAGING OF TIDALLY HEATED EXOMOONS

    SciTech Connect

    Peters, Mary Anne; Turner, Edwin L.

    2013-06-01

    We demonstrate the ability of existing and planned telescopes, on the ground and in space, to directly image tidally heated exomoons orbiting gas-giant exoplanets. Tidally heated exomoons can plausibly be far more luminous than their host exoplanet and as much as 0.1% as bright as the system's stellar primary if it is a low mass star. Because emission from exomoons can be powered by tidal forces, they can shine brightly at arbitrarily large separations from the system's stellar primary with temperatures of several hundreds degrees Kelvin or even higher in extreme cases. Furthermore, these high temperatures can occur in systems that are billions of years old. Tidally heated exomoons may thus be far easier targets for direct imaging studies than giant exoplanets which must be both young and at a large projected separation (typically at least tens of AU) from their primary to be accessible to current generation direct imaging studies. For example, the (warm) Spitzer Space Telescope and the next generation of ground based instruments could detect an exomoon roughly the size of the Earth at a temperature Almost-Equal-To 600 K and a distance Almost-Equal-To 5 pc in the K, L, and M bands at the 5{sigma} confidence level with a one hour exposure; in more favorable but still plausible cases, detection at distances of tens of parsecs is feasible. Future mid-infrared space telescopes, such as James Webb Space Telescope and SPICA, will be capable of directly imaging tidally heated exomoons around the nearest two dozen stars with a brightness temperature {>=}300 K and R {>=} 1 R{sub Circled-Plus} orbiting at {>=}12 AU from the primary star at a 5{sigma} confidence level in a 10{sup 4} s integration. In addition it is possible that some of the exoplanets which have already been directly imaged are actually tidally heated exomoons or blends of such objects with hot young planets. If such exomoons exist and are sufficiently common (i.e., nearby), it may well be far easier to

  10. Molecular Ultrasound Imaging: Current Status and Future Directions

    PubMed Central

    Deshpande, Nirupama; Needles, Andrew; Willmann, Jürgen K.

    2011-01-01

    Targeted contrast-enhanced ultrasound (molecular ultrasound) is an emerging imaging strategy that combines ultrasound technology with novel molecularly-targeted ultrasound contrast agents for assessing biological processes at the molecular level. Molecular ultrasound contrast agents are nano- or micro-sized particles that are targeted to specific molecular markers by adding high-affinity binding ligands onto the surface of the particles. Following intravenous administration, these targeted ultrasound contrast agents accumulate at tissue sites overexpressing specific molecular markers, thereby enhancing the ultrasound imaging signal. High spatial and temporal resolution, real-time imaging, non-invasiveness, relatively low costs, lack of ionizing irradiation and wide availability of ultrasound systems are advantages compared to other molecular imaging modalities. In this article we review current concepts and future directions of molecular ultrasound imaging, including different classes of molecular ultrasound contrast agents, ongoing technical developments of preclinical and clinical ultrasound systems , the potential of molecular ultrasound for imaging different diseases at the molecular level, and the translation of molecular ultrasound into the clinic. PMID:20541656

  11. 3D Synchrotron Imaging of a Directionally Solidified Ternary Eutectic

    NASA Astrophysics Data System (ADS)

    Dennstedt, Anne; Helfen, Lukas; Steinmetz, Philipp; Nestler, Britta; Ratke, Lorenz

    2016-03-01

    For the first time, the microstructure of directionally solidified ternary eutectics is visualized in three dimensions, using a high-resolution technique of X-ray tomography at the ESRF. The microstructure characterization is conducted with a photon energy, allowing to clearly discriminate the three phases Ag2Al, Al2Cu, and α-Aluminum solid solution. The reconstructed images illustrate the three-dimensional arrangement of the phases. The Ag2Al lamellae perform splitting and merging as well as nucleation and disappearing events during directional solidification.

  12. Compressed Sensing Photoacoustic Imaging Based on Fast Alternating Direction Algorithm

    PubMed Central

    Liu, Xueyan; Peng, Dong; Guo, Wei; Ma, Xibo; Yang, Xin; Tian, Jie

    2012-01-01

    Photoacoustic imaging (PAI) has been employed to reconstruct endogenous optical contrast present in tissues. At the cost of longer calculations, a compressive sensing reconstruction scheme can achieve artifact-free imaging with fewer measurements. In this paper, an effective acceleration framework using the alternating direction method (ADM) was proposed for recovering images from limited-view and noisy observations. Results of the simulation demonstrated that the proposed algorithm could perform favorably in comparison to two recently introduced algorithms in computational efficiency and data fidelity. In particular, it ran considerably faster than these two methods. PAI with ADM can improve convergence speed with fewer ultrasonic transducers, enabling a high-performance and cost-effective PAI system for biomedical applications. PMID:23365553

  13. Magnetic Resonance Imaging Conditional Pacemakers: Rationale, Development and Future Directions

    PubMed Central

    Cronin, Edmond M; Wilkoff, Bruce L

    2012-01-01

    Pacemakers and other cardiac implantable electronic devices (CIEDs) have long been considered an absolute contraindication to magnetic resonance imaging (MRI), a crucial and growing imaging modality. In the last 20 years, protocols have been developed to allow MR scanning of CIED patients with a low complication rate. However, this practice has remained limited to a relatively small number of centers, and many pacemaker patients continue to be denied access to clinically indicated imaging. The introduction of MRI conditional pacemakers has provided a widely applicable and satisfactory solution to this problem. Here, the interactions of pacemakers with the MR environment, the results of MR scanning in patients with conventional CIEDs, the development and clinical experience with MRI conditional devices, and future directions are reviewed. PMID:23071382

  14. Performance analysis of an inexpensive Direct Imaging Transmission Ion Microscope

    NASA Astrophysics Data System (ADS)

    Barnes, Patrick; Pallone, Arthur

    2013-03-01

    A direct imaging transmission ion microscope (DITIM) is built from a modified webcam and a commercially available polonium-210 antistatic device mounted on an optics rail. The performance of the DITIM in radiographic mode is analyzed in terms of the line spread function (LSF) and modulation transfer function (MTF) for an opaque edge. Limitations of, potential uses for, and suggested improvements to the DITIM are also discussed. Faculty sponsor

  15. Imaging of Temporomandibular Joint: Approach by Direct Volume Rendering

    PubMed Central

    Caradonna, Carola; Bruschetta, Daniele; Vaccarino, Gianluigi; Milardi, Demetrio

    2014-01-01

    Background: The purpose of this study was to conduct a morphological analysis of the temporomandibular joint, a highly specialized synovial joint that permits movement and function of the mandible. Materials and Methods: We have studied the temporom-andibular joint anatomy, directly on the living, from 3D images obtained by medical imaging Computed Tomography and Nuclear Magnetic Resonance acquisition, and subsequent re-engineering techniques 3D Surface Rendering and Volume Rendering. Data were analysed with the goal of being able to isolate, identify and distinguish the anatomical structures of the joint, and get the largest possible number of information utilizing software for post-processing work. Results: It was possible to reproduce anatomy of the skeletal structures, as well as through acquisitions of Magnetic Resonance Imaging; it was also possible to visualize the vascular, muscular, ligamentous and tendinous components of the articular complex, and also the capsule and the fibrous cartilaginous disc. We managed the Surface Rendering and Volume Rendering, not only to obtain three-dimensional images for colour and for resolution comparable to the usual anatomical preparations, but also a considerable number of anatomical, minuter details, zooming, rotating and cutting the same images with linking, graduating the colour, transparency and opacity from time to time. Conclusion: These results are encouraging to stimulate further studies in other anatomical districts. PMID:25664280

  16. Fingerprint image enhancement method using directional median filter

    NASA Astrophysics Data System (ADS)

    Wu, Chaohong; Shi, Zhixin; Govindaraju, Venu

    2004-08-01

    The performance of any fingerprint recognizer highly depends on the fingerprint image quality. Different types of noises in the fingerprint images pose greater difficulty for recognizers. Most Automatic Fingerprint Identification Systems (AFIS) use some form of image enhancement. Although several methods have been described in the literature, there is still scope for improvement. In particular, effective methodology of cleaning the valleys between the ridge contours are lacking. We observe that noisy valley pixels and the pixels in the interrupted ridge flow gap are "impulse noises". Therefore, this paper describes a new approach to fingerprint image enhancement, which is based on integration of Anisotropic Filter and directional median filter(DMF). Gaussian-distributed noises are reduced effectively by Anisotropic Filter, "impulse noises" are reduced efficiently by DMF. Usually, traditional median filter is the most effective method to remove pepper-and-salt noise and other small artifacts, the proposed DMF can not only finish its original tasks, it can also join broken fingerprint ridges, fill out the holes of fingerprint images, smooth irregular ridges as well as remove some annoying small artifacts between ridges. The enhancement algorithm has been implemented and tested on fingerprint images from FVC2002. Images of varying quality have been used to evaluate the performance of our approach. We have compared our method with other methods described in the literature in terms of matched minutiae, missed minutiae, spurious minutiae, and flipped minutiae(between end points and bifurcation points). Experimental results show our method to be superior to those described in the literature.

  17. Rapid imaging of surgical breast excisions using direct temporal sampling two photon fluorescent lifetime imaging

    PubMed Central

    Giacomelli, Michael G.; Sheikine, Yuri; Vardeh, Hilde; Connolly, James L.; Fujimoto, James G.

    2015-01-01

    Two photon fluorescent lifetime imaging is a modality that enables depth-sectioned, molecularly-specific imaging of cells and tissue using intrinsic contrast. However, clinical applications have not been well explored due to low imaging speed and limited field of view, which make evaluating large pathology samples extremely challenging. To address these limitations, we have developed direct temporal sampling two photon fluorescent lifetime imaging (DTS-FLIM), a method which enables a several order of magnitude increase in imaging speed by capturing an entire lifetime decay in a single fluorescent excitation. We use this greatly increased speed to perform a preliminary study using gigapixel-scale imaging of human breast pathology surgical specimens. PMID:26600997

  18. The Direct Imaging Search of Exoplanets from Ground and Space

    NASA Astrophysics Data System (ADS)

    Dou, Jiangpei; Ren, Deqing; Zhu, Yongtian

    2015-08-01

    Exoplanets search is one of the hottest topics in both modern astronomy and public domain. Until now over 1990 exoplanets have been confirmed mostly by the indirect radial velocity and transiting approaches, yielding several important physical information such as masses and radius. The study of the physics of planet formation and evolution will focus on giant planets through the direct imaging.However, the direct imaging of exoplanets remains challenging, due to the large flux ratio difference and the nearby angular distance. In recent years, the extreme adaptive optics (Ex-AO) coronagraphic instrumentation has been proposed and developed on 8-meter class telescopes, which is optimized for the high-contrast imaging observation from ground, for the giant exoplanets and other faint stellar companions. Gemini Planet Imager (GPI) has recently come to its first light, with a development period over 10 years. The contrast level has been pushed to 10-6. Due to the space limitation or this or other reasons, none professional adaptive optics is available for most of current 3~4 meter class telescopes, which will limit its observation power to some extent, especially in the research of high-contrast imaging of exoplanets.In this presentation, we will report the latest observation results by using our Extreme Adaptive Optics (Ex-AO) as a visiting instrument for high-contrast imaging on ESO’s 3.58-meter NTT telescope at LSO, and on 3.5-meter ARC telescope at Apache Point Observatory, respectively. It has demonstrated the Ex-AO can be used for the scientific research of exoplanets and brown dwarfs. With a update of the currect configuration with critical hardware, the dedicated instrument called as EDICT for imaging research of young giant exoplanets will be presented. Meanwhile, we have fully demonstrated in the lab a contrast on the order of 10-9 in a large detection area, which is a critical technique for future Earth-like exoplanets imaging space missions. And a space

  19. Beyond Kepler: Direct Imaging of Earth-like Planets

    NASA Technical Reports Server (NTRS)

    Belikov, Ruslan

    2012-01-01

    Is there another Earth out there? Is there life on it? People have been asking these questions for over two thousand years, and we finally stand on the verge of answering them. The Kepler space telescope is NASA's first mission designed to study Earthlike exoplanets (exo-Earths), and it will soon tell us how often exo-Earths occur in the habitable zones of their stars. The next natural step after Kepler is spectroscopic characterization of exo-Earths, which would tell us whether they possess an atmosphere, oxygen, liquid water, as well as other biomarkers. In order to do this, directly imaging an exo-Earth may be necessary (at least for Sun-like stars). Directly imaging an exo-Earth is challenging and likely requires a flagship-size optical space telescope with an unprecedented imaging system capable of achieving contrasts of 1(exp 10) very close to the diffraction limit. Several coronagraphs and external occulters have been proposed to meet this challenge and are in development. After first overviewing the history and current state of the field, my talk will focus on the work proceeding at the Ames Coronagraph Experiment (ACE) at the NASA Ames Research Center, where we are developing the Phase Induced Amplitude Apodization (PIAA) coronagraph in a collaboration with JPL. PIAA is a powerful technique with demonstrated aggressive performance that defines the state of the art at small inner working angles. At ACE, we have achieved contrasts of 2(exp -8) with an inner working angle of 2 lambda/D and 1(exp -6) at 1.4 lambda/D. On the path to exo-Earth imaging, we are also pursuing a smaller telescope concept called EXCEDE (EXoplanetary Circumstellar Environments and Disk Explorer), which was recently selected for technology development (Category III) by NASA's Explorer program. EXCEDE will do fundamental science on debris disks as well as serve as a technological and scientific pathfinder for an exo-Earth imaging mission.

  20. Direction-dependent localization errors in SPECT images

    SciTech Connect

    Roper, Justin; Bowsher, James; Yin Fangfang

    2010-09-15

    Purpose: Single photon emission computed tomography (SPECT) is being investigated for imaging inside radiation therapy treatment rooms to localize biological targets. Here, computer simulations were used to analyze locational and directional dependencies in localization errors and to assess the effects of spatial resolution modeling and observer normalization on localization performance. Methods: SPECT images of the XCAT phantom, containing 12 hot tumors, were reconstructed with detector response function compensation (DRC) and without DRC (nDRC). Numerical observers were forced to select the most suspicious tumor location, using normalized cross correlation (NXC) or un-normalized cross correlation (XC), from 3 cm diameter search volumes that each contained only one tumor. For each tumor site, localization was optimized as a function of the iteration number and postreconstruction smoothing. Localization error, the distance between true and estimated tumor positions, was calculated across the ensembles of 80 images. Direction-dependent localization bias and precision were estimated from the image ensemble. Results: For the six superficial tumors in close proximity to the detector trajectory, mean localization errors were <2 mm and were lowest or comparable using DRC-NXC, though differences from DRC-XC and nDRC-NXC were not statistically significant. DRC-NXC did provide statistically significantly better localization than nDRC-XC for five of these six tumors. At the other six sites where attenuation was more severe and the distance was generally greater between the tumor and detector, DRC typically did not show better localization than nDRC. Observer normalization improved the localization substantially for a tumor near the hotter heart. Localization errors were anisotropic and dependent on tumor location relative to the detector trajectory. Conclusions: This computer-simulation study compared localization performance for normalized and un-normalized numerical

  1. Weighted Model Components for Gradient Direction Matching in Overhead Images

    SciTech Connect

    Grant, C W; Nikolaev, S; Paglieroni, D W

    2006-03-17

    Gradient direction matching (GDM) is the main target identification algorithm used in the Image Content Engine project at Lawrence Livermore National Laboratory. GDM is a 3D solid model-based edge-matching algorithm which does not require explicit edge extraction from the source image. The GDM algorithm is presented, identifying areas where performance enhancement seems possible. Improving the process of producing model gradient directions from the solid model by assigning different weights to different parts of the model is an extension tested in the current study. Given a simple geometric model, we attempt to determine, without obvious semantic clues, if different weight values produce significantly better matching accuracy, and how those weights should be assigned to produce the best matching accuracy. Two simple candidate strategies for assigning weights are proposed--pixel-weighted and edge-weighted. We adjust the weights of the components in a simple model of a tractor/semi-trailer using relevance feedback to produce an optimal set of weights for this model and a particular test image. The optimal weights are then compared with pixel and edge-weighting strategies to determine which is most suitable and under what circumstances.

  2. Diffusion imaging quality control via entropy of principal direction distribution.

    PubMed

    Farzinfar, Mahshid; Oguz, Ipek; Smith, Rachel G; Verde, Audrey R; Dietrich, Cheryl; Gupta, Aditya; Escolar, Maria L; Piven, Joseph; Pujol, Sonia; Vachet, Clement; Gouttard, Sylvain; Gerig, Guido; Dager, Stephen; McKinstry, Robert C; Paterson, Sarah; Evans, Alan C; Styner, Martin A

    2013-11-15

    Diffusion MR imaging has received increasing attention in the neuroimaging community, as it yields new insights into the microstructural organization of white matter that are not available with conventional MRI techniques. While the technology has enormous potential, diffusion MRI suffers from a unique and complex set of image quality problems, limiting the sensitivity of studies and reducing the accuracy of findings. Furthermore, the acquisition time for diffusion MRI is longer than conventional MRI due to the need for multiple acquisitions to obtain directionally encoded Diffusion Weighted Images (DWI). This leads to increased motion artifacts, reduced signal-to-noise ratio (SNR), and increased proneness to a wide variety of artifacts, including eddy-current and motion artifacts, "venetian blind" artifacts, as well as slice-wise and gradient-wise inconsistencies. Such artifacts mandate stringent Quality Control (QC) schemes in the processing of diffusion MRI data. Most existing QC procedures are conducted in the DWI domain and/or on a voxel level, but our own experiments show that these methods often do not fully detect and eliminate certain types of artifacts, often only visible when investigating groups of DWI's or a derived diffusion model, such as the most-employed diffusion tensor imaging (DTI). Here, we propose a novel regional QC measure in the DTI domain that employs the entropy of the regional distribution of the principal directions (PD). The PD entropy quantifies the scattering and spread of the principal diffusion directions and is invariant to the patient's position in the scanner. High entropy value indicates that the PDs are distributed relatively uniformly, while low entropy value indicates the presence of clusters in the PD distribution. The novel QC measure is intended to complement the existing set of QC procedures by detecting and correcting residual artifacts. Such residual artifacts cause directional bias in the measured PD and here called

  3. Diffusion imaging quality control via entropy of principal direction distribution

    PubMed Central

    Oguz, Ipek; Smith, Rachel G.; Verde, Audrey R.; Dietrich, Cheryl; Gupta, Aditya; Escolar, Maria L.; Piven, Joseph; Pujol, Sonia; Vachet, Clement; Gouttard, Sylvain; Gerig, Guido; Dager, Stephen; McKinstry, Robert C.; Paterson, Sarah; Evans, Alan C.; Styner, Martin A.

    2013-01-01

    Diffusion MR imaging has received increasing attention in the neuroimaging community, as it yields new insights into the microstructural organization of white matter that are not available with conventional MRI techniques. While the technology has enormous potential, diffusion MRI suffers from a unique and complex set of image quality problems, limiting the sensitivity of studies and reducing the accuracy of findings. Furthermore, the acquisition time for diffusion MRI is longer than conventional MRI due to the need for multiple acquisitions to obtain directionally encoded Diffusion Weighted Images (DWI). This leads to increased motion artifacts, reduced signal-to-noise ratio (SNR), and increased proneness to a wide variety of artifacts, including eddy-current and motion artifacts, “venetian blind” artifacts, as well as slice-wise and gradient-wise inconsistencies. Such artifacts mandate stringent Quality Control (QC) schemes in the processing of diffusion MRI data. Most existing QC procedures are conducted in the DWI domain and/or on a voxel level, but our own experiments show that these methods often do not fully detect and eliminate certain types of artifacts, often only visible when investigating groups of DWI's or a derived diffusion model, such as the most-employed diffusion tensor imaging (DTI). Here, we propose a novel regional QC measure in the DTI domain that employs the entropy of the regional distribution of the principal directions (PD). The PD entropy quantifies the scattering and spread of the principal diffusion directions and is invariant to the patient's position in the scanner. High entropy value indicates that the PDs are distributed relatively uniformly, while low entropy value indicates the presence of clusters in the PD distribution. The novel QC measure is intended to complement the existing set of QC procedures by detecting and correcting residual artifacts. Such residual artifacts cause directional bias in the measured PD and here

  4. Photoacoustic lifetime imaging for direct in vivo tissue oxygen monitoring

    PubMed Central

    Shao, Qi; Ashkenazi, Shai

    2015-01-01

    Abstract. Measuring the partial pressure of oxygen (pO2) in tissue may provide physicians with essential information about the physiological state of tissue. However, currently available methods for measuring or imaging tissue pO2 have significant limitations, preventing them from being widely used in clinics. Recently, we have reported a direct and noninvasive in vivo imaging modality based on the photoacoustic lifetime which overcomes certain drawbacks of the existing methods. The technique maps the excited triplet state of oxygen-sensitive dye, thus reflecting the spatial and temporal distributions of tissue oxygen. Here, we present two studies which apply photoacoustic lifetime imaging (PALI) to monitor changes of tissue oxygen induced by external modulations. The first study modulates tissue oxygen by controlling the percentage of oxygen a normal mouse inhales. We demonstrate that PALI is able to reflect the change in oxygen level with respect to normal, oxygen-rich, and oxygen-poor breathing conditions. The second study involves an acute ischemia model using a thin thread tied around the hindlimb of a normal mouse to reduce the blood flow. PALI images were acquired before, during, and after the restriction. The drop of tissue pO2 and recovery from hypoxia due to reperfusion were tracked and observed by PALI. PMID:25748857

  5. Photoacoustic lifetime imaging for direct in vivo tissue oxygen monitoring

    NASA Astrophysics Data System (ADS)

    Shao, Qi; Ashkenazi, Shai

    2015-03-01

    Measuring the partial pressure of oxygen (pO2) in tissue may provide physicians with essential information about the physiological state of tissue. However, currently available methods for measuring or imaging tissue pO2 have significant limitations, preventing them from being widely used in clinics. Recently, we have reported a direct and noninvasive in vivo imaging modality based on the photoacoustic lifetime which overcomes certain drawbacks of the existing methods. The technique maps the excited triplet state of oxygen-sensitive dye, thus reflecting the spatial and temporal distributions of tissue oxygen. Here, we present two studies which apply photoacoustic lifetime imaging (PALI) to monitor changes of tissue oxygen induced by external modulations. The first study modulates tissue oxygen by controlling the percentage of oxygen a normal mouse inhales. We demonstrate that PALI is able to reflect the change in oxygen level with respect to normal, oxygen-rich, and oxygen-poor breathing conditions. The second study involves an acute ischemia model using a thin thread tied around the hindlimb of a normal mouse to reduce the blood flow. PALI images were acquired before, during, and after the restriction. The drop of tissue pO2 and recovery from hypoxia due to reperfusion were tracked and observed by PALI.

  6. Direct imaging of the coda of teleseismic P waves

    NASA Astrophysics Data System (ADS)

    Pavlis, Gary L.

    This paper reviews the theoretical background of existing techniques for direct imaging of the coda of teleseismic P waves. A unifying theme of all approaches is the Born series for elastic wave scattering. Inversion methods for one-dimensional structure commonly included multiply scattered waves while all existing two and three-dimensional implementations are limited by a single scattering approximation that defines a linear inverse problem in material property perturbations. The problem has an analytic inverse because the forward problem can be cast as a generalized Radon transform with line/surface integrals along single scatterer isochrons. The inverse Radon transform can then be applied to estimate scattering strength at a given point as a linear combination of all data that match a time and polarization constraint. I describe how backprojection, Kirchhoff approximations, and inverse scattering approaches are related to the fundamental scattering equations. I introduce a new concept called the exploding converter model that is a useful physical model for understanding imaging techniques and show how it is related to the Born integral equation. Finally, I discuss limitation on imaging imposed by deconvolution of the incident wavefield. I show that deconvolution is based on an incorrect assumption because it neglects a propagator term from the base of the imaging volume to the free surface. I give the correct form of the deconvolution operator and suggest it may be possible to improve deconvolution through application of downward continuation operators that enter in these equations.

  7. Direct Imaging of the Coda of Teleseismic P waves

    NASA Astrophysics Data System (ADS)

    Pavlis, G. L.

    2002-12-01

    This paper reviews the theoretical background of existing techniques for direct imaging of the coda of teleseismic P waves. A unifying theme of all approaches is the Born series for elastic wave scattering. Inversion methods for one-dimensional structure commonly included multiply scattered waves while all existing two and three-dimensional implementations are limited by a single scattering approximation that defines a linear inverse problem in material property perturbations. The problem has an analytic inverse because the forward problem can be cast as a generalized Radon transform with line/surface integrals along single scatterer isocrons. The inverse Radon transform can then be applied to estimate scattering strength at a given point as a linear combination of all data that match a time and polarization constraint. I describe how backprojection, Kirchoff approximations, and inverse scattering approachs are related to the fundamental scattering equations. I introduce a new concept called the exploding converter model that is a useful physical model for understanding imaging techniques and show how it is related to the Born integral equation. Finally, I discuss limitation on imaging imposed by deconvolution of the incident wavefield. I show that deconvolution is based on an incorrect assumption because it neglects a propagator term from the base of the imaging volume to the free surface. I give the correct form of the deconvolution operator and suggest it may be possible to improve deconvolution through application of downward continuation operators that enter in these equations.

  8. Direct-Solve Image-Based Wavefront Sensing

    NASA Technical Reports Server (NTRS)

    Lyon, Richard G.

    2009-01-01

    A method of wavefront sensing (more precisely characterized as a method of determining the deviation of a wavefront from a nominal figure) has been invented as an improved means of assessing the performance of an optical system as affected by such imperfections as misalignments, design errors, and fabrication errors. The method is implemented by software running on a single-processor computer that is connected, via a suitable interface, to the image sensor (typically, a charge-coupled device) in the system under test. The software collects a digitized single image from the image sensor. The image is displayed on a computer monitor. The software directly solves for the wavefront in a time interval of a fraction of a second. A picture of the wavefront is displayed. The solution process involves, among other things, fast Fourier transforms. It has been reported to the effect that some measure of the wavefront is decomposed into modes of the optical system under test, but it has not been reported whether this decomposition is postprocessing of the solution or part of the solution process.

  9. Colors of Alien Worlds from Direct Imaging Exoplanet Missions

    NASA Astrophysics Data System (ADS)

    Hu, Renyu

    2015-08-01

    Future direct-imaging exoplanet missions such as WFIRST/AFTA, Exo-C, and Exo-S will measure the reflectivity of exoplanets at visible wavelengths. Most of the exoplanets to be observed will be located further away from their parent stars than is Earth from the Sun. These “cold” exoplanets have atmospheric environments conducive for the formation of water and/or ammonia clouds, like Jupiter in the Solar System. I find the mixing ratio of methane and the pressure level of the uppermost cloud deck on these planets can be uniquely determined from their reflection spectra, with moderate spectral resolution, if the cloud deck is between 0.6 and 1.5 bars. The existence of this unique solution is useful for exoplanet direct imaging missions for several reasons. First, the weak bands and strong bands of methane enable the measurement of the methane mixing ratio and the cloud pressure, although an overlying haze layer can bias the estimate of the latter. Second, the cloud pressure, once derived, yields an important constraint on the internal heat flux from the planet, and thus indicating its thermal evolution. Third, water worlds having H2O-dominated atmospheres are likely to have water clouds located higher than the 10-3 bar pressure level, and muted spectral absorption features. These planets would occupy a confined phase space in the color-color diagrams, likely distinguishable from H2-rich giant exoplanets by broadband observations. Therefore, direct-imaging exoplanet missions may offer the capability to broadly distinguish H2-rich giant exoplanets versus H2O-rich super-Earth exoplanets, and to detect ammonia and/or water clouds and methane gas in their atmospheres.

  10. Colors of Alien Worlds from Direct Imaging Exoplanet Missions

    NASA Astrophysics Data System (ADS)

    Hu, Renyu

    2016-01-01

    Future direct-imaging exoplanet missions such as WFIRST will measure the reflectivity of exoplanets at visible wavelengths. Most of the exoplanets to be observed will be located further away from their parent stars than is Earth from the Sun. These "cold" exoplanets have atmospheric environments conducive for the formation of water and/or ammonia clouds, like Jupiter in the Solar System. I find the mixing ratio of methane and the pressure level of the uppermost cloud deck on these planets can be uniquely determined from their reflection spectra, with moderate spectral resolution, if the cloud deck is between 0.6 and 1.5 bars. The existence of this unique solution is useful for exoplanet direct imaging missions for several reasons. First, the weak bands and strong bands of methane enable the measurement of the methane mixing ratio and the cloud pressure, although an overlying haze layer can bias the estimate of the latter. Second, the cloud pressure, once derived, yields an important constraint on the internal heat flux from the planet, and thus indicating its thermal evolution. Third, water worlds having H2O-dominated atmospheres are likely to have water clouds located higher than the 10-3 bar pressure level, and muted spectral absorption features. These planets would occupy a confined phase space in the color-color diagrams, likely distinguishable from H2-rich giant exoplanets by broadband observations. Therefore, direct-imaging exoplanet missions may offer the capability to broadly distinguish H2-rich giant exoplanets versus H2O-rich super-Earth exoplanets, and to detect ammonia and/or water clouds and methane gas in their atmospheres.

  11. Direct imaging of myocardial ischemia: a potential new paradigm in nuclear cardiovascular imaging.

    PubMed

    Jain, Diwakar; He, Zuo-Xiang

    2008-01-01

    Myocardial perfusion imaging has been in clinical use for over 30 years, serving as an effective, reliable, and relatively simple tool for diagnosis, risk stratification, and long-term follow-up of patients with suspected or known coronary artery disease. However, a unique strength of nuclear imaging is its ability to provide tools for imaging biochemical and metabolic processes and receptor and transporter functions at molecular and cellular levels in intact organisms under a wide variety of physiologic conditions. Despite their high resolution and technical sophistication, other imaging modalities currently do not have this capability. Metabolic imaging techniques using radiolabeled free fatty acid and glucose analogs provide a unique ability to image myocardial ischemia directly in patients with known or suspected coronary artery disease. These techniques can potentially overcome some of the limitations of currently used stress-rest perfusion imaging and also provide a unique opportunity to detect and image an episode of ischemia in the preceding hours even in the absence of other markers of ongoing myocardial ischemia. We describe recent studies using fluorine 18-labeled deoxyglucose and iodine 123 beta-methyl-p-iodophenyl-pentadecanoic acid for imaging myocardial ischemia. PMID:18761264

  12. Direct imaging of radio-frequency modes via traveling wave magnetic resonance imaging

    NASA Astrophysics Data System (ADS)

    Tonyushkin, A.; Deelchand, D. K.; Van de Moortele, P.-F.; Adriany, G.; Kiruluta, A.

    2016-01-01

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

  13. Direct imaging of quantum wires nucleated at diatomic steps

    SciTech Connect

    Molina, S. I.; Varela, M.; Sales, D. L.; Ben, T.; Pizarro, J.; Galindo, P. L.; Fuster, D.; Gonzalez, Y.; Gonzalez, L.; Pennycook, S. J.

    2007-10-01

    Atomic steps at growth surfaces are important heterogeneous sources for nucleation of epitaxial nano-objects. In the presence of misfit strain, we show that the nucleation process takes place preferentially at the upper terrace of the step as a result of the local stress relaxation. Evidence for strain-induced nucleation comes from the direct observation by postgrowth, atomic resolution, Z-contrast imaging of an InAs-rich region in a nanowire located on the upper terrace surface of an interfacial diatomic step.

  14. Search for Exoplanets around Young Stellar Objects by Direct Imaging

    NASA Astrophysics Data System (ADS)

    Uyama, Taichi; Tamura, Motohide; Hashimoto, Jun; Kuzuhara, Masayuki

    2015-12-01

    SEEDS project, exploring exoplanets and protoplanetary disks with Subaru/HiCIAO, has observed about 500 stars by Direct Imaging from 2009 Dec to 2015 Apr. Among these targets we explore around Young Stellar Objects (YSOs; age ≦ 10Myr) which often have the protoplanetary disks where planets are being formed in order to detect young exoplanets and to understand the formation process. We analyzed 66 YSOs (about 100 data in total) with LOCI data reduction. We will report the results (companion candidates and detection limit) of our exploration.

  15. Direct imaging of rotating molecules anchored on graphene

    NASA Astrophysics Data System (ADS)

    Choe, Jeongheon; Lee, Yangjin; Fang, Lei; Lee, Gun-Do; Bao, Zhenan; Kim, Kwanpyo

    2016-07-01

    There has been significant research interest in controlling and imaging molecular dynamics, such as translational and rotational motions, especially at a single molecular level. Here we applied aberration-corrected transmission electron microscopy (ACTEM) to actuate and directly image the rotational motions of molecules anchored on a single-layer-graphene sheet. Nanometer-sized carbonaceous molecules anchored on graphene provide ideal systems for monitoring rotational motions via ACTEM. We observed the preferential registry of longer molecular axis along graphene zigzag or armchair lattice directions due to the stacking-dependent molecule-graphene energy landscape. The calculated cross section from elastic scattering theory was used to experimentally estimate the rotational energy barriers of molecules on graphene. The observed energy barrier was within the range of 1.5-12 meV per atom, which is in good agreement with previous calculation results. We also performed molecular dynamics simulations, which revealed that the edge atoms of the molecule form stably bonds to graphene defects and can serve as a pivot point for rotational dynamics. Our study demonstrates the versatility of ACTEM for the investigation of molecular dynamics and configuration-dependent energetics at a single molecular level.There has been significant research interest in controlling and imaging molecular dynamics, such as translational and rotational motions, especially at a single molecular level. Here we applied aberration-corrected transmission electron microscopy (ACTEM) to actuate and directly image the rotational motions of molecules anchored on a single-layer-graphene sheet. Nanometer-sized carbonaceous molecules anchored on graphene provide ideal systems for monitoring rotational motions via ACTEM. We observed the preferential registry of longer molecular axis along graphene zigzag or armchair lattice directions due to the stacking-dependent molecule-graphene energy landscape. The

  16. Magnetic particle imaging: current developments and future directions

    PubMed Central

    Panagiotopoulos, Nikolaos; Duschka, Robert L; Ahlborg, Mandy; Bringout, Gael; Debbeler, Christina; Graeser, Matthias; Kaethner, Christian; Lüdtke-Buzug, Kerstin; Medimagh, Hanne; Stelzner, Jan; Buzug, Thorsten M; Barkhausen, Jörg; Vogt, Florian M; Haegele, Julian

    2015-01-01

    Magnetic particle imaging (MPI) is a novel imaging method that was first proposed by Gleich and Weizenecker in 2005. Applying static and dynamic magnetic fields, MPI exploits the unique characteristics of superparamagnetic iron oxide nanoparticles (SPIONs). The SPIONs’ response allows a three-dimensional visualization of their distribution in space with a superb contrast, a very high temporal and good spatial resolution. Essentially, it is the SPIONs’ superparamagnetic characteristics, the fact that they are magnetically saturable, and the harmonic composition of the SPIONs’ response that make MPI possible at all. As SPIONs are the essential element of MPI, the development of customized nanoparticles is pursued with the greatest effort by many groups. Their objective is the creation of a SPION or a conglomerate of particles that will feature a much higher MPI performance than nanoparticles currently available commercially. A particle’s MPI performance and suitability is characterized by parameters such as the strength of its MPI signal, its biocompatibility, or its pharmacokinetics. Some of the most important adjuster bolts to tune them are the particles’ iron core and hydrodynamic diameter, their anisotropy, the composition of the particles’ suspension, and their coating. As a three-dimensional, real-time imaging modality that is free of ionizing radiation, MPI appears ideally suited for applications such as vascular imaging and interventions as well as cellular and targeted imaging. A number of different theories and technical approaches on the way to the actual implementation of the basic concept of MPI have been seen in the last few years. Research groups around the world are working on different scanner geometries, from closed bore systems to single-sided scanners, and use reconstruction methods that are either based on actual calibration measurements or on theoretical models. This review aims at giving an overview of current developments and

  17. HUBBLE SPACE TELESCOPE CAPTURES FIRST DIRECT IMAGE OF A STAR

    NASA Technical Reports Server (NTRS)

    2002-01-01

    This is the first direct image of a star other than the Sun, made with NASA's Hubble Space Telescope. Called Alpha Orionis, or Betelgeuse, it is a red supergiant star marking the shoulder of the winter constellation Orion the Hunter (diagram at right). The Hubble image reveals a huge ultraviolet atmosphere with a mysterious hot spot on the stellar behemoth's surface. The enormous bright spot, more than ten times the diameter of Earth, is at least 2,000 Kelvin degrees hotter than the surface of the star. The image suggests that a totally new physical phenomenon may be affecting the atmospheres of some stars. Follow-up observations will be needed to help astronomers understand whether the spot is linked to oscillations previously detected in the giant star, or whether it moves systematically across the star's surface under the grip of powerful magnetic fields. The observations were made by Andrea Dupree of the Harvard- Smithsonian Center for Astrophysics in Cambridge, MA, and Ronald Gilliland of the Space Telescope Science Institute in Baltimore, MD, who announced their discovery today at the 187th meeting of the American Astronomical Society in San Antonio, Texas. The image was taken in ultraviolet light with the Faint Object Camera on March 3, 1995. Hubble can resolve the star even though the apparent size is 20,000 times smaller than the width of the full Moon -- roughly equivalent to being able to resolve a car's headlights at a distance of 6,000 miles. Betelgeuse is so huge that, if it replaced the Sun at the center of our Solar System, its outer atmosphere would extend past the orbit of Jupiter (scale at lower left). Credit: Andrea Dupree (Harvard-Smithsonian CfA), Ronald Gilliland (STScI), NASA and ESA Image files in GIF and JPEG format and captions may be accessed on Internet via anonymous ftp from oposite.stsci.edu in /pubinfo.

  18. The LEECH Exoplanet Imaging Survey: Characterization of the Coldest Directly Imaged Exoplanet, GJ 504 b, and Evidence for Superstellar Metallicity

    NASA Astrophysics Data System (ADS)

    Skemer, Andrew J.; Morley, Caroline V.; Zimmerman, Neil T.; Skrutskie, Michael F.; Leisenring, Jarron; Buenzli, Esther; Bonnefoy, Mickael; Bailey, Vanessa; Hinz, Philip; Defrére, Denis; Esposito, Simone; Apai, Dániel; Biller, Beth; Brandner, Wolfgang; Close, Laird; Crepp, Justin R.; De Rosa, Robert J.; Desidera, Silvano; Eisner, Josh; Fortney, Jonathan; Freedman, Richard; Henning, Thomas; Hofmann, Karl-Heinz; Kopytova, Taisiya; Lupu, Roxana; Maire, Anne-Lise; Males, Jared R.; Marley, Mark; Morzinski, Katie; Oza, Apurva; Patience, Jenny; Rajan, Abhijith; Rieke, George; Schertl, Dieter; Schlieder, Joshua; Stone, Jordan; Su, Kate; Vaz, Amali; Visscher, Channon; Ward-Duong, Kimberly; Weigelt, Gerd; Woodward, Charles E.

    2016-02-01

    As gas giant planets and brown dwarfs radiate away the residual heat from their formation, they cool through a spectral type transition from L to T, which encompasses the dissipation of cloud opacity and the appearance of strong methane absorption. While there are hundreds of known T-type brown dwarfs, the first generation of directly imaged exoplanets were all L type. Recently, Kuzuhara et al. announced the discovery of GJ 504 b, the first T dwarf exoplanet. GJ 504 b provides a unique opportunity to study the atmosphere of a new type of exoplanet with a ˜500 K temperature that bridges the gap between the first directly imaged planets (˜1000 K) and our own solar system's Jupiter (˜130 K). We observed GJ 504 b in three narrow L-band filters (3.71, 3.88, and 4.00 μm), spanning the red end of the broad methane fundamental absorption feature (3.3 μm) as part of the LBTI Exozodi Exoplanet Common Hunt (LEECH) exoplanet imaging survey. By comparing our new photometry and literature photometry with a grid of custom model atmospheres, we were able to fit GJ 504 b's unusual spectral energy distribution for the first time. We find that GJ 504 b is well fit by models with the following parameters: Teff = 544 ± 10 K, g < 600 m s-2, [M/H] = 0.60 ± 0.12, cloud opacity parameter of fsed = 2-5, R = 0.96 ± 0.07 RJup, and log(L) = -6.13 ± 0.03 L⊙, implying a hot start mass of 3-30 Mjup for a conservative age range of 0.1-6.5 Gyr. Of particular interest, our model fits suggest that GJ 504 b has a superstellar metallicity. Since planet formation can create objects with nonstellar metallicities, while binary star formation cannot, this result suggests that GJ 504 b formed like a planet, not like a binary companion. The LBT is an international collaboration among institutions in the United States, Italy, and Germany. LBT Corporation partners are the University of Arizona on behalf of the Arizona university system; Istituto Nazionale di Astrophisica, Italy; LBT

  19. Advances in Focal Plane Wavefront Estimation for Directly Imaging Exoplanets

    NASA Astrophysics Data System (ADS)

    Eldorado Riggs, A. J.; Kasdin, N. Jeremy; Groff, Tyler Dean

    2015-01-01

    To image cold exoplanets directly in visible light, an instrument on a telescope needs to suppress starlight by about 9 orders of magnitude at small separations from the star. A coronagraph changes the point spread function to create regions of high contrast where exoplanets or disks can be seen. Aberrations on the optics degrade the contrast by several orders of magnitude, so all high-contrast imaging systems incorporate one or more deformable mirrors (DMs) to recover regions of high contrast. With a coronagraphic instrument planned for the WFIRST-AFTA space telescope, there is a pressing need for faster, more robust estimation and control schemes for the DMs. Non-common path aberrations limit conventional phase conjugation schemes to medium star-to-planet contrast ratios of about 1e-6. High-contrast imaging requires estimation and control of both phase and amplitude in the same beam path as the science camera. Field estimation is a challenge since only intensity is measured; the most common approach, including that planned for WFIRST-AFTA, is to use DMs to create diversity, via pairs of small probe shapes, thereby allowing disambiguation of the electric field. Most implementations of DM Diversity require at least five images per electric field estimate and require narrowband measurements. This paper describes our new estimation algorithms that improve the speed (by using fewer images) and bandwidth of focal plane wavefront estimation. For narrowband estimation, we are testing nonlinear, recursive algorithms such as an iterative extended Kalman filter (IEKF) to use three images each iteration and build better, more robust estimates. We are also exploring the use of broadband estimation without the need for narrowband sub-filters and measurements. Here we present simulations of these algorithms with realistic noise and small signals to show how they might perform for WFIRST-AFTA. Once validated in simulations, we will test these algorithms experimentally in

  20. Direct imaging of rotating molecules anchored on graphene.

    PubMed

    Choe, Jeongheon; Lee, Yangjin; Fang, Lei; Lee, Gun-Do; Bao, Zhenan; Kim, Kwanpyo

    2016-07-21

    There has been significant research interest in controlling and imaging molecular dynamics, such as translational and rotational motions, especially at a single molecular level. Here we applied aberration-corrected transmission electron microscopy (ACTEM) to actuate and directly image the rotational motions of molecules anchored on a single-layer-graphene sheet. Nanometer-sized carbonaceous molecules anchored on graphene provide ideal systems for monitoring rotational motions via ACTEM. We observed the preferential registry of longer molecular axis along graphene zigzag or armchair lattice directions due to the stacking-dependent molecule-graphene energy landscape. The calculated cross section from elastic scattering theory was used to experimentally estimate the rotational energy barriers of molecules on graphene. The observed energy barrier was within the range of 1.5-12 meV per atom, which is in good agreement with previous calculation results. We also performed molecular dynamics simulations, which revealed that the edge atoms of the molecule form stably bonds to graphene defects and can serve as a pivot point for rotational dynamics. Our study demonstrates the versatility of ACTEM for the investigation of molecular dynamics and configuration-dependent energetics at a single molecular level. PMID:27333828

  1. Planet Diversity Yields with Space-based Direct Imaging Telescopes

    NASA Astrophysics Data System (ADS)

    Domagal-Goldman, Shawn; Kopparapu, Ravi Kumar; Hébrard, Eric; Stark, Chris; Robinson, Tyler D.; Roberge, Aki; Mandell, Avi; McElwain, Michael W.; Clampin, Mark; Meadows, Victoria; Arney, Giada; Advanced Technology Large Aperture Space Telescope Science Team, Exoplanet Climate Group

    2016-01-01

    In this presentation, we will estimate the yield for a diversity of planets from future space-based flagship telescopes. We first divvy up planets into categories that are based on current observables, and that should impact the spectra we hope to observe in the future. The two main classification parameters we use here are the size of a planet and the energy flux into the planet's atmosphere. These two parameters are measureable or inferable from present-day observations, and should have a strong influence on future spectroscopy observations from JWST, WFIRST (with a coronagraph and/or starshade), and concept flagship missions that would fly some time after WFIRST. This allows us to calculate "ηplanet" values for each kind of planet. These η values then allow calculations of the expected yields from direct imaging missions, by leveraging the models and prior work by Stark and colleagues (2014, 2015). That work estimated the yields for potentially Earth-like worlds (i.e. of a size and stellar irradiation consistent with definitions of the habitable zone) for telescopes with a variety of observational parameters. We will do the same thing here, but for a wider variety of planets. This will allow us to discuss the implications of architecture and instrument properties on the diversity of worlds that future direct imaging missions would observe.

  2. Wide Giant Planets are Rare: Planet Demographics from Direct Imaging

    NASA Astrophysics Data System (ADS)

    Biller, Beth

    2015-08-01

    The previous generation of direct imaging surveys probed samples of 100-200 stars with AO-driven coronagraphic imaging and advanced techniques such as Angular Differential Imaging (ADI) (e.g. surveys such as SEEDS, IDPS, the NICI Science Campaign, among others). These surveys found that wide giant planets are comparatively rare, especially at separations > 50 AU: for instance, Biller et al. 2013 find for a sample of 78 young moving group stars that the the frequency of 1-20 M Jup companions at semi-major axes from 10-150 AU is <18% at a 95.4% confidence level using DUSTY models and <6% at a 95.4% using COND models. As next generation planet-finding cameras such as GPI at Gemini, SPHERE at VLT, project 1640, and SceXAO at Suburu come online, our understanding of wide planet populations is likely to undergo a rapid evolution, especially for planets at separations of 10-50 AU. New large-scale surveys (400-500 stars) are now underway with these new instruments, e.g. NIRSUR with SPHERE and GPIES with GPI. In this talk, I will review the previous generation of surveys and the statistical results that they have yielded. I will also discuss prospects for the new generation of ongoing surveys.

  3. Direct Atom Imaging by Chemical-Sensitive Holography.

    PubMed

    Lühr, Tobias; Winkelmann, Aimo; Nolze, Gert; Krull, Dominique; Westphal, Carsten

    2016-05-11

    In order to understand the physical and chemical properties of advanced materials, functional molecular adsorbates, and protein structures, a detailed knowledge of the atomic arrangement is essential. Up to now, if subsurface structures are under investigation, only indirect methods revealed reliable results of the atoms' spatial arrangement. An alternative and direct method is three-dimensional imaging by means of holography. Holography was in fact proposed for electron waves, because of the electrons' short wavelength at easily accessible energies. Further, electron waves are ideal structure probes on an atomic length scale, because electrons have a high scattering probability even for light elements. However, holographic reconstructions of electron diffraction patterns have in the past contained severe image artifacts and were limited to at most a few tens of atoms. Here, we present a general reconstruction algorithm that leads to high-quality atomic images showing thousands of atoms. Additionally, we show that different elements can be identified by electron holography for the example of FeS2. PMID:27070050

  4. High-speed nonsilver lithographic system for laser direct imaging

    NASA Astrophysics Data System (ADS)

    DoMinh, Thap

    1991-08-01

    A high-speed nonsilver lithographic system has been demonstrated for direct laser imaging. The system is negative working and is based on a photoinsolubilization of a polymer coating by redox amplification. The essential components consist of a cobalt(III)amine (Coen), a redox transfer ligand (PAN), a light-sensitive quinone (Q), and a polysulfonamide binder (A6). On exposure, the quinone photogenerates a hydroquinone reducing agent. On heating, the hydroquinone reduces Coen to produce Co(II). PAN then complexes this Co(II) to form CO(II) PAN which, in turn, reduces more Coen. This resulting reaction produces Co(III)PAN and more Co(II) centers, which in the presence of excess PAN and Coen continues the cycle, giving photographically useful amplification. Polysulfonamide (A6) is an excellent medium with optimal acidity and thermomechanical properties to promote this chemistry. It provides toughness required for a dry-film photoresist, ink receptivity for lithographic plate, and aqueous development for both applications. Exposure to an Argon ion laser (4881514nm) at dose O.5-lmj/cm2 followed by heating (5 sec/120 C hot plate) produced high-density images that were insolubilized in an aqueous alkaline developer to give final nonswell images of excellent quality.

  5. Ambient Mass Spectrometry Imaging Using Direct Liquid Extraction Techniques

    SciTech Connect

    Laskin, Julia; Lanekoff, Ingela

    2015-11-13

    Mass spectrometry imaging (MSI) is a powerful analytical technique that enables label-free spatial localization and identification of molecules in complex samples.1-4 MSI applications range from forensics5 to clinical research6 and from understanding microbial communication7-8 to imaging biomolecules in tissues.1, 9-10 Recently, MSI protocols have been reviewed.11 Ambient ionization techniques enable direct analysis of complex samples under atmospheric pressure without special sample pretreatment.3, 12-16 In fact, in ambient ionization mass spectrometry, sample processing (e.g., extraction, dilution, preconcentration, or desorption) occurs during the analysis.17 This substantially speeds up analysis and eliminates any possible effects of sample preparation on the localization of molecules in the sample.3, 8, 12-14, 18-20 Venter and co-workers have classified ambient ionization techniques into three major categories based on the sample processing steps involved: 1) liquid extraction techniques, in which analyte molecules are removed from the sample and extracted into a solvent prior to ionization; 2) desorption techniques capable of generating free ions directly from substrates; and 3) desorption techniques that produce larger particles subsequently captured by an electrospray plume and ionized.17 This review focuses on localized analysis and ambient imaging of complex samples using a subset of ambient ionization methods broadly defined as “liquid extraction techniques” based on the classification introduced by Venter and co-workers.17 Specifically, we include techniques where analyte molecules are desorbed from solid or liquid samples using charged droplet bombardment, liquid extraction, physisorption, chemisorption, mechanical force, laser ablation, or laser capture microdissection. Analyte extraction is followed by soft ionization that generates ions corresponding to intact species. Some of the key advantages of liquid extraction techniques include the ease

  6. Direct thermal imaging of circumstellar discs and exo-planets

    NASA Astrophysics Data System (ADS)

    Pantin, Eric; Siebenmorgen, Ralf; Cavarroc, Celine; Sterzik, Michael F.

    2008-07-01

    The phase A study of a mid infrared imager and spectrograph for the European Extremely Large Telescope (E-ELT), called METIS, was endorsed in May 2008. Two key science drivers of METIS are: a) direct thermal imaging of exo-planets and b) characterization of circumstellar discs from the early proto-planetary to the late debris phase. Observations in the 10μm atmospheric window (N band) require a contrast ratio between stellar light and emitted photons from the exo-planet or the disc of ~ 105. At shorter wavelengths the contrast between star and reflected light from the planet-disc system exceeds >~ 107 posing technical challenges. By means of end-to-end detailed simulations we demonstrate that the superb spatial resolution of a 42m telescope in combination with stellar light rejection methods such as coronagraphic or differential imaging will allow detections at 10μm for a solar type system down to a star-planet separation of 0.1" and a mass limit for irradiated planets of 1 Jupiter (MJ) mass. In case of self-luminous planets observations are possible further out e.g. at the separation limit of JWST of ~ 0.7", METIS will detect planets >~5MJ. This allows to derive a census of all such exo-planets by means of thermal imaging in a volume limited sample of up to 6pc. In addition, METIS will provide the possibility to study the chemical composition of atmospheres of exo-planets using spectroscopy at moderate spectral resolution (λ/Δλ ~ 100) for the brightest targets. Based on detailed performance and sensitivity estimates, we demonstrate that a mid-infrared instrument on an ELT is perfectly suited to observe gravitationally created structures such as gaps in proto- and post- planetary discs, in a complementary way to space missions (e.g. JWST, SOFIA) and ALMA which can only probe the cold dust emission further out.

  7. Direct imaging and spectroscopic characterization of habitable planets with ELTs

    NASA Astrophysics Data System (ADS)

    Guyon, Olivier; Jovanovic, Nemanja; Lozi, Julien

    2015-12-01

    While the ~1e10 reflected light contrast between Earth-like planets and Sun-like stars is extremely challenging to overcome for ground-based telescopes, habitable planets around lower-mass stars can be "only" a 10 million times fainter than their host stars. Thanks to the small angular resolution offered by upcoming extremely large telescopes (ELTs) and recent advances in wavefront control and coronagraphic techniques, direct imaging and spectroscopic characterization of habitable planets will be possible around nearby M-type stars. Deep (~1e-8) contrast can be achieved by combining (1) sensitive fast visible light wavefront sensing (extreme-AO) with (2) kHz speckle control in the near-IR and (3) high efficiency coronagraphy. Spectroscopy will measure abundances of water, oxygen and methane, measure the planet rotation period, orbit, and identify main surface features through time-domain spectrophotometry.The Subaru Coronagraphic Extreme AO (SCExAO) system is a technology precursor to such a habitable planet imager for ELTs, and is currently under active development. By combining small inner working angle coronagraphy, visible-WFS based extreme-AO and fast speckle control, it will include the key elements of a future ELT system able to image and characterize habitable planets. We describe a technical plan to evolve SCExAO into a habitable planet imager for the Thirty Meter Telescope (TMT), which is aimed at providing such scientific capability during the 2020 decade, and inform the design, deployment and scientific operation of a more capable Extreme-AO instrument.

  8. Direct curvature correction for noncontact imaging modalities applied to multispectral imaging

    PubMed Central

    Kainerstorfer, Jana M.; Amyot, Franck; Ehler, Martin; Hassan, Moinuddin; Demos, Stavros G.; Chernomordik, Victor; Hitzenberger, Christoph K.; Gandjbakhche, Amir H.; Riley, Jason D.

    2010-01-01

    Noncontact optical imaging of curved objects can result in strong artifacts due to the object’s shape, leading to curvature biased intensity distributions. This artifact can mask variations due to the object’s optical properties, and makes reconstruction of optical∕physiological properties difficult. In this work we demonstrate a curvature correction method that removes this artifact and recovers the underlying data, without the necessity of measuring the object’s shape. This method is applicable to many optical imaging modalities that suffer from shape-based intensity biases. By separating the spatially varying data (e.g., physiological changes) from the background signal (dc component), we show that the curvature can be extracted by either averaging or fitting the rows and columns of the images. Numerical simulations show that our method is equivalent to directly removing the curvature, when the object’s shape is known, and accurately recovers the underlying data. Experiments on phantoms validate the numerical results and show that for a given image with 16.5% error due to curvature, the method reduces that error to 1.2%. Finally, diffuse multispectral images are acquired on forearms in vivo. We demonstrate the enhancement in image quality on intensity images, and consequently on reconstruction results of blood volume and oxygenation distributions. PMID:20799815

  9. Exozodiacal Dust and Direct Imaging of Extrasolar Planets

    NASA Technical Reports Server (NTRS)

    Kuchner, Marc

    2008-01-01

    Direct imaging of extrasolar planets means contending with dust from extrasolar asteroids and comets. This 'exozodiacal dust' creates a structured background light that can easily outshine the light from an exoEarth and confuse a planet-search mission like TPF or TOPS. But exozodiacal dust can be both friend and foe: planets can stir dust clouds into patterns that reveal the presence of the planet and constrain its mass and orbit. I'll describe some recent research on this topic: 3-D dynamical models of dust clouds with planets and searches for exozodiacal dust with the Keck Interferometer. The author also offers a prediction for the typical zodiacal dust background found around solar analogs, based on seafloor sediment data.

  10. Exoplanet Community Report on Direct Infrared Imaging of Exoplanets

    NASA Technical Reports Server (NTRS)

    Danchi, William C.; Lawson, Peter R.

    2009-01-01

    Direct infrared imaging and spectroscopy of exoplanets will allow for detailed characterization of the atmospheric constituents of more than 200 nearby Earth-like planets, more than is possible with any other method under consideration. A flagship mission based on larger passively cooled infrared telescopes and formation flying technologies would have the highest angular resolution of any concept under consideration. The 2008 Exoplanet Forum committee on Direct Infrared Imaging of Exoplanets recommends: (1) a vigorous technology program including component development, integrated testbeds, and end-to-end modeling in the areas of formation flying and mid-infrared nulling; (2) a probe-scale mission based on a passively cooled structurally connected interferometer to be started within the next two to five years, for exoplanetary system characterization that is not accessible from the ground, and which would provide transformative science and lay the engineering groundwork for the flagship mission with formation flying elements. Such a mission would enable a complete exozodiacal dust survey (<1 solar system zodi) in the habitable zone of all nearby stars. This information will allow for a more efficient strategy of spectral characterization of Earth-sized planets for the flagship missions, and also will allow for optimization of the search strategy of an astrometric mission if such a mission were delayed due to cost or technology reasons. (3) Both the flagship and probe missions should be pursued with international partners if possible. Fruitful collaboration with international partners on mission concepts and relevant technology should be continued. (4) Research and Analysis (R&A) should be supported for the development of preliminary science and mission designs. Ongoing efforts to characterize the the typical level of exozodiacal light around Sun-like stars with ground-based nulling technology should be continued.

  11. Direct Imaging Searches with the Apodizing Phase Plate Coronagraph

    NASA Astrophysics Data System (ADS)

    Kenworthy, M.; Meshkat, T.; Otten, , G.; Codona, J.

    2014-03-01

    The sensitivity of direct imaging searches for extrasolar planets is limited by the presence of diffraction rings from the primary star. Coronagraphs are angular filters that minimise these diffraction structures whilst allowing light from faint companions to shine through. The Apodizing Phase Plate (APP; Kenworthy 2007) coronagraph is a simple pupil plane optic that suppresses diffraction over a 180 degree region around each star simultaneously, providing easy beam switching observations and requiring no time consuming optical alignment at the telescope. We will present our results on using the APP at the Very Large Telescope in surveys for extrasolar planets around A/F and debris disk hosting stars in the L' band (3.8 microns) in the Southern Hemisphere, where we reach a contrast of 12 magnitudes at 0.5 arcseconds (Meshkat 2013). In Leiden, we are also developing the next generation of broadband achromatic coronagraphs that can simultaneously image both sides of the star using Vector APPs (Snik 2012, Otten 2012). Recent laboratory results showing the potential of this technology for future ELTs will also be presented.

  12. Rapamycin/DiR loaded lipid-polyaniline nanoparticles for dual-modal imaging guided enhanced photothermal and antiangiogenic combination therapy.

    PubMed

    Wang, Jinping; Guo, Fang; Yu, Meng; Liu, Li; Tan, Fengping; Yan, Ran; Li, Nan

    2016-09-10

    Imaging-guided photothermal therapy (PTT) has promising application for treating tumors. Nevertheless, so far imaging-guided photothermal drug-delivery systems have been developed with limited success for tumor chemo-photothermal therapy. In this study, as the proof-of-concept, a stimuli-responsive tumor-targeting rapamycin/DiR loaded lipid-polyaniline nanoparticle (RDLPNP) for dual-modal imaging-guided enhanced PTT efficacy is reported for the first time. In this system, polyaniline (PANI) with π-π electronic conjugated system and effective photothermal efficiency is chosen as the appropriate model receptor of fluorescence resonance energy transfer (FRET), and loaded cyanine probe (e.g., 1,1-dioctadecyl-3,3,3,3-tetramethylindotricarbocyanine iodide, DiR) acts as the donor of near-infrared fluorescence (NIRF). In addition, rapamycin (RAPA), which is used as the antiangiogenesis chemotherapeutic drug, can cutdown the tumor vessels and delay tumor growth obviously. After intravenous treatment of RDLPNPs into Hela tumor bearing mice, fluorescent (from DiR) and enhanced photoacoustic (from DLPNPs) signals were found in tumor site over time, which reached to peak at the 6h time point. After irradiating with an NIR laser, a good anti-tumor effect was observed owing to the enhanced photothermal and antiangiogenic effect of RDLPNPs. These results show that the multifunctional nanoparticle can be used as a promising imaging-guided photothermal drug delivery nanoplatform for cancer therapy. PMID:27388755

  13. Directional x-ray dark-field imaging of strongly ordered systems

    SciTech Connect

    Jensen, Torben Haugaard; Feidenhans'l, Robert; Bech, Martin; Pfeiffer, Franz; Zanette, Irene; Weitkamp, Timm; David, Christian; Rutishauser, Simon; Deyhle, Hans; Reznikova, Elena; Mohr, Juergen

    2010-12-01

    Recently a novel grating based x-ray imaging approach called directional x-ray dark-field imaging was introduced. Directional x-ray dark-field imaging yields information about the local texture of structures smaller than the pixel size of the imaging system. In this work we extend the theoretical description and data processing schemes for directional dark-field imaging to strongly scattering systems, which could not be described previously. We develop a simple scattering model to account for these recent observations and subsequently demonstrate the model using experimental data. The experimental data includes directional dark-field images of polypropylene fibers and a human tooth slice.

  14. Separation of multiple images via directional guidance using structured prism and pyramid arrays.

    PubMed

    Lee, Hyemin; Seo, Hyein; Kang, Sunghwan; Yoon, Hyunsik

    2016-09-01

    We propose a new concept of separating images through a directional guide of multi-visuals by using structured prism or pyramid arrays. By placing prism arrays onto two different image arrays, the two collective images below the facets are guided to different directions. Using optical calculations, we identify a condition for successful image separation. Transparent pyramid arrays are used to separate four images into four directions. The direction of refracted rays can be controlled by the refractive index of prisms and liquid filled into the voids. In addition, the images can be switched by stretching and releasing an elastomeric prism array. PMID:27607698

  15. Thermokarst Lake Gyre Flow Speed and Direction Derivation Using Image Matching from Sequential Satellite Images

    NASA Astrophysics Data System (ADS)

    Zhan, S.; Wang, S.; Beck, R. A.; Liu, H.; Hinkel, K. M.

    2014-12-01

    Thermokarst lakes on the Arctic Coastal Plain of northern Alaska are closely coupled with the regional climate through energy, water and carbon budgets. These lakes exhibit striking elongated shapes perpendicular to the prevailing wind direction. This has led to the hypothesis that the expansion of lakes is caused by thermomechanical processes induced by wind-driven water circulation. The predominant bimodal wind regime in the region (easterly and westerly wind) redistributes lake sediment towards the west and east shores to form protective littoral shelves while the north and south shores are preferentially eroded. Previous research on wind-driven circulation in thermokarst lakes was mainly based on in situ studies which can only collect sparse measurements and is time-consuming. Examination of satellite imagery clearly reveals the wide-spread presence of gyres in thermokarst lakes. It allows the study of gyres and other circulation patterns at both lake and regional scales. This study examines the movement (speed, direction) of a 10-km-wide gyre using a Landsat-7 and an ASTER scene taken about 40 minutes apart. These two images are matched using a robust image matching technique based on cross-correlation. Flow speed and direction for the gyre are extracted from the images and are compared with the in situ measurements collected during previous field work. This study provides insight into the evolution of thermokarst lakes and their interaction with the local climate by quantifying gyre circulation rates over entire lakes.

  16. ATMOSPHERIC DYNAMICS OF BROWN DWARFS AND DIRECTLY IMAGED GIANT PLANETS

    SciTech Connect

    Showman, Adam P.; Kaspi, Yohai

    2013-10-20

    A variety of observations provide evidence for vigorous motion in the atmospheres of brown dwarfs and directly imaged giant planets. Motivated by these observations, we examine the dynamical regime of the circulation in the atmospheres and interiors of these objects. Brown dwarfs rotate rapidly, and for plausible wind speeds, the flow at large scales will be rotationally dominated. We present three-dimensional, global, numerical simulations of convection in the interior, which demonstrate that at large scales, the convection aligns in the direction parallel to the rotation axis. Convection occurs more efficiently at high latitudes than low latitudes, leading to systematic equator-to-pole temperature differences that may reach ∼1 K near the top of the convection zone. The interaction of convection with the overlying, stably stratified atmosphere will generate a wealth of atmospheric waves, and we argue that, as in the stratospheres of planets in the solar system, the interaction of these waves with the mean flow will cause a significant atmospheric circulation at regional to global scales. At large scales, this should consist of stratified turbulence (possibly organizing into coherent structures such as vortices and jets) and an accompanying overturning circulation. We present an approximate analytic theory of this circulation, which predicts characteristic horizontal temperature variations of several to ∼50 K, horizontal wind speeds of ∼10-300 m s{sup –1}, and vertical velocities that advect air over a scale height in ∼10{sup 5}-10{sup 6} s. This vertical mixing may help to explain the chemical disequilibrium observed on some brown dwarfs. Moreover, the implied large-scale organization of temperature perturbations and vertical velocities suggests that near the L/T transition, patchy clouds can form near the photosphere, helping to explain recent observations of brown-dwarf variability in the near-IR.

  17. Direct Imaging of Gene-Carrier Complexes in Animal Cells

    NASA Astrophysics Data System (ADS)

    Lin, Alison J.; Slack, Nelle L.; Ahmad, Ayesha; Matsumoto, Brian; Safinya, Cyrus R.

    1998-03-01

    Cationic lipids are promising gene carriers for DNA transfection. Establishing the correlations between structures of cationic lipid/DNA complexes (CL-DNA) and pathways of transfection will greatly aid us in achieving the optimal CL-DNA transfections. Our first step is to determine the uptake mechanism of DNA by studying the interactions and structures of DNA and cationic lipids. X-ray diffraction shows that the CL-DNA undergoes structural phase transitions from lamellar( J. Raedler, I. Koltover, T. Salditt, C. R. Safinya, Science 275, 810 (1997).) to inverted hexagonal self-assemblies as we change the lipid composition. X-ray diffraction and optical microscopy techniques are used to directly image the progress of the CL-DNA in mouse L-cells and unravel the complex structure in-situ. Fluorescence and confocal optical microscopy techniques allow us to monitor the interactions between the complexes and different organelles in the cell cytoplasm. Current results indicate that once inside cells, complexes containing DOPE follow a different pathway from those containing DOPC. This research is funded by NSF-DMR-9624091, PRF-31352-AC7, and Los Alamos-STB/UC:96-108.

  18. Chemistry and Structure of Graphene Oxide via Direct Imaging.

    PubMed

    Dave, Shreya H; Gong, Chuncheng; Robertson, Alex W; Warner, Jamie H; Grossman, Jeffrey C

    2016-08-23

    Graphene oxide (GO) and reduced GO (rGO) are the only variants of graphene that can be manufactured at the kilogram scale, and yet the widely accepted model for their structure has largely relied on indirect evidence. Notably, existing high-resolution transmission electron microscopy (HRTEM) studies of graphene oxide report long-range order of sp(2) lattice with isolated defect clusters. Here, we present HRTEM evidence of a different structural form of GO, where nanocrystalline regions of sp(2) lattice are surrounded by regions of disorder. The presence of contaminants that adsorb to the surface of the material at room temperature normally prevents direct observation of the intrinsic atomic structure of this defective GO. To overcome this, we use an in situ heating holder within an aberration-corrected TEM (AC-TEM) to study the atomic structure of this nanocrystalline graphene oxide from room temperature to 700 °C. As the temperature increases to above 500 °C, the adsorbates detach from the GO and the underlying atomic structure is imaged to be small 2-4 nm crystalline domains within a polycrystalline GO film. By combining spectroscopic evidence with the AC-TEM data, we support the dynamic interpretation of the structural evolution of graphene oxide. PMID:27397115

  19. Design challenges and gaps in standards in developing an interoperable zero footprint DI thin client for use in image-enabled electronic health record solutions

    NASA Astrophysics Data System (ADS)

    Agrawal, Arun; Koff, David; Bak, Peter; Bender, Duane; Castelli, Jane

    2015-03-01

    The deployment of regional and national Electronic Health Record solutions has been a focus of many countries throughout the past decade. A major challenge for these deployments has been support for ubiquitous image viewing. More specifically, these deployments require an imaging solution that can work over the Internet, leverage any point of service device: desktop, tablet, phone; and access imaging data from any source seamlessly. Whereas standards exist to enable ubiquitous image viewing, few if any solutions exist that leverage these standards and meet the challenge. Rather, most of the currently available web based DI viewing solutions are either proprietary solutions or require special plugins. We developed a true zero foot print browser based DI viewing solution based on the Web Access DICOM Objects (WADO) and Cross-enterprise Document Sharing for Imaging (XDS-I.b) standards to a) demonstrate that a truly ubiquitous image viewer can be deployed; b) identify the gaps in the current standards and the design challenges for developing such a solution. The objective was to develop a viewer, which works on all modern browsers on both desktop and mobile devices. The implementation allows basic viewing functionalities of scroll, zoom, pan and window leveling (limited). The major gaps identified in the current DICOM WADO standards are a lack of ability to allow any kind of 3D reconstruction or MPR views. Other design challenges explored include considerations related to optimization of the solution for response time and low memory foot print.

  20. Vector analysis for direction prediction on image strings

    NASA Astrophysics Data System (ADS)

    Tickle, Andrew J.; Grindley, Josef E.

    2012-10-01

    Vector analysis is a well-developed field that deals with details about line, surface and volume integrals which can be solved analytically to provide solutions to many problems. Using vector analysis, a curve can be divided up into many small arcs, each of which is a position vector. The summation of these position vectors can be used to represent the curve in detail; this is known as the total vector field. In this paper, there is shown a vector analysis methodology when applied to the wake immediately after a moving or stationary object, caused by the movement of the object through free space or the surrounding medium moving around the object respectively. The aim was to create a system that can determine the vectors between successive images in a video with the end result being able to establish an overall trajectory of the object. This could be implemented on a Field Programmable Gate Array (FPGA) or other device to be deployed in the field to track any type of object. If the device's orientation with magnetic north-south is known, the direction of the object is travelling in can be calculated and then relayed on. This could be useful as an easily deployable warning system for the armed forces or rescue services to inform personnel of potential incoming threats. This work builds upon the Morphological Scene Change Detection (MSCD) mechanism implemented in the DSP Builder environment and describes how the changes allow the system to track the wake and plot its trajectory. System simulations of real world data are shown and the resultant imagery is then discussed. Furthermore, tests are conducted on single objects and then multiple objects to investigate how the system responds as real world situations are likely to have more than a single object.

  1. Inflammatory bowel disease imaging: Current practice and future directions

    PubMed Central

    Kilcoyne, Aoife; Kaplan, Jess L; Gee, Michael S

    2016-01-01

    The purpose of this paper is to evaluate the role of imaging in inflammatory bowel disease (IBD), including detection of extraluminal complications and extraintestinal manifestations of IBD, assessment of disease activity and treatment response, and discrimination of inflammatory from fibrotic strictures. IBD is a chronic idiopathic disease affecting the gastrointestinal tract that is comprised of two separate, but related intestinal disorders; Crohn’s disease and ulcerative colitis. The paper discusses, in detail the pros and cons of the different IBD imaging modalities that need to be considered in order to optimize the imaging and clinical evaluation of patients with IBD. Historically, IBD evaluation of the bowel has included imaging to assess the portions of the small bowel that are inaccessible to optical endoscopic visualization. This traditionally was performed using barium fluoroscopic techniques; however, cross-sectional imaging techniques (computed tomography and magnetic resonance imaging) are being increasingly utilized for IBD evaluation because they can simultaneously assess mural and extramural IBD manifestations. Recent advances in imaging technology, that continue to improve the ability of imaging to noninvasively follow disease activity and treatment response, are also discussed. This review article summarizes the current imaging approach in inflammatory bowel disease as well as the role of emerging imaging modalities. PMID:26811637

  2. Evaluation of the veracity of one work by the artist Di Cavalcanti through non-destructive techniques: XRF, imaging and brush stroke analysis

    NASA Astrophysics Data System (ADS)

    Kajiya, E. A. M.; Campos, P. H. O. V.; Rizzutto, M. A.; Appoloni, C. R.; Lopes, F.

    2014-02-01

    This paper presents systematic studies and analysis that contributed to the identification of the forgery of a work by the artist Emiliano Augusto Cavalcanti de Albuquerque e Melo, known as Di Cavalcanti. The use of several areas of expertise such as brush stroke analysis ("pinacologia"), applied physics, and art history resulted in an accurate diagnosis for ascertaining the authenticity of the work entitled "Violeiro" (1950). For this work we used non-destructive methods such as techniques of infrared, ultraviolet, visible and tangential light imaging combined with chemical analysis of the pigments by portable X-Ray Fluorescence (XRF) and graphic gesture analysis. Each applied method of analysis produced specific information that made possible the identification of materials and techniques employed and we concluded that this work is not consistent with patterns characteristic of the artist Di Cavalcanti.

  3. Directed evolution of a magnetic resonance imaging contrast agent for noninvasive imaging of dopamine

    PubMed Central

    Shapiro, Mikhail G; Westmeyer, Gil G; Romero, Philip A; Szablowski, Jerzy O; Küster, Benedict; Shah, Ameer; Otey, Christopher R; Langer, Robert; Arnold, Frances H; Jasanoff, Alan

    2011-01-01

    The development of molecular probes that allow in vivo imaging of neural signaling processes with high temporal and spatial resolution remains challenging. Here we applied directed evolution techniques to create magnetic resonance imaging (MRI) contrast agents sensitive to the neurotransmitter dopamine. The sensors were derived from the heme domain of the bacterial cytochrome P450-BM3 (BM3h). Ligand binding to a site near BM3h’s paramagnetic heme iron led to a drop in MRI signal enhancement and a shift in optical absorbance. Using an absorbance-based screen, we evolved the specificity of BM3h away from its natural ligand and toward dopamine, producing sensors with dissociation constants for dopamine of 3.3–8.9 μM. These molecules were used to image depolarization-triggered neurotransmitter release from PC12 cells and in the brains of live animals. Our results demonstrate the feasibility of molecular-level functional MRI using neural activity–dependent sensors, and our protein engineering approach can be generalized to create probes for other targets. PMID:20190737

  4. High-speed four-color infrared digital imaging for studying in-cylinder processes in a DI diesel engine

    NASA Astrophysics Data System (ADS)

    Rhee, K. T.

    1995-07-01

    The study was to investigate in-cylinder events of a direct injection-type diesel engine by using a new high-speed infrared (IR) digital imaging systems for obtaining information that was difficult to achieve by the conventional devices. For this, a new high-speed dual-spectra infrared digital imaging system was developed to simultaneously capture two geometrically identical (in respective spectral) sets of IR images having discrete digital information in a (64x64) matrix at rates as high as over 1,800 frames/sec each with exposure period as short as 20 micron sec. At the same time, a new advanced four-color W imaging system was constructed. The first two sets of spectral data were the radiation from water vapor emission bands to compute the distributions of temperature and specie in the gaseous mixture and the remaining two sets of data were to find the instantaneous temperature distribution over the cylinder surface. More than eight reviewed publications have been produced to report many new findings including: Distributions of Water Vapor and Temperature in a Flame; End Gas Images Prior to Onset of Knock; Effect of MTBE on Diesel Combustion; Impact of Oxygen Enrichment on In-cylinder Reactions; Spectral IR Images of Spray Plume; Residual Gas Distribution; Preflame Reactions in Diesel Combustion; Preflame Reactions in the End Gas of an SI Engine; Postflame Oxidation; and Liquid Fuel Layers during Combustion in an SI Engine. In addition, some computational analysis of diesel combustion was performed using KIVA-II program in order to compare results from the prediction and the measurements made using the new IR imaging diagnostic tool.

  5. Directional binary wavelet patterns for biomedical image indexing and retrieval.

    PubMed

    Murala, Subrahmanyam; Maheshwari, R P; Balasubramanian, R

    2012-10-01

    A new algorithm for medical image retrieval is presented in the paper. An 8-bit grayscale image is divided into eight binary bit-planes, and then binary wavelet transform (BWT) which is similar to the lifting scheme in real wavelet transform (RWT) is performed on each bitplane to extract the multi-resolution binary images. The local binary pattern (LBP) features are extracted from the resultant BWT sub-bands. Three experiments have been carried out for proving the effectiveness of the proposed algorithm. Out of which two are meant for medical image retrieval and one for face retrieval. It is further mentioned that the database considered for three experiments are OASIS magnetic resonance imaging (MRI) database, NEMA computer tomography (CT) database and PolyU-NIRFD face database. The results after investigation shows a significant improvement in terms of their evaluation measures as compared to LBP and LBP with Gabor transform. PMID:21822675

  6. Direct Exoplanet Imaging around Sun-like Stars: Beating the Speckle Noise with Innovative Imaging Techniques

    NASA Astrophysics Data System (ADS)

    Marois, Christian; Doyon, R.; Racine, R.; Nadeau, D.; Lafreniere, D.; Vallee, P.; Riopel, M.; Macintosh, B.

    2005-08-01

    Indirect surveys have now uncovered more than 150 exoplanets, but are limited to planets close to the star and measure only the projected mass and orbital parameters. Both photometry and spectroscopy of exoplanets are required to derive their physical characteristics. The star to exoplanet intensity ratio (>108 in the near infrared) and the relative separation (< 0.5 arcseconds) significantly complicate this endeavour. Current ground- and space-based direct imaging surveys achieve an intensity ratio up to 104 at 0.5. separation, a factor 10,000 from the desired goal. These surveys are limited by uncorrected atmospheric turbulence and optical surface imperfections that produce quasi-static speckles that look like exoplanets, but much brighter. Two techniques will be discussed to attenuate this speckle noise. The first is the Simultaneous Spectral Differential Imaging technique (SSDI), acquiring a number of images simultaneously at different adjacent narrowband wavelengths and combining them to attenuate speckles. The second is the Angular Differential Imaging technique (ADI), taking multiple observations while rotating the telescope or waiting for sufficient field rotation to subtract static speckles and to preserve the companion flux. Results from a dedicated SSDI camera "TRIDENT" that was mounted under PUEO/CFHT and from an ongoing ADI survey at Gemini with Altair/NIRI will be presented. Future work involving a new type of detector, the Multi-Color Detector Assembly (MCDA), will also be discussed. Combining these observation strategies and new detectors are of particular interest for specialized exoplanet finder instruments for 10-m telescopes that are currently under study, like ExAOC at Gemini, and future space-based observatories like TPF.

  7. Reconstructing chromosphere concentration images directly by continuous-wave diffuse optical tomography.

    PubMed

    Li, Ang; Zhang, Quan; Culver, Joseph P; Miller, Eric L; Boas, David A

    2004-02-01

    We present an algorithm to reconstruct chromosphere concentration images directly rather than following the traditional two-step process of reconstructing wavelength-dependent absorption coefficient images and then calculating chromosphere concentration images. This procedure imposes prior spectral information into the image reconstruction that results in a dramatic improvement in the image contrast-to-noise ratio of better than 100%. We demonstrate this improvement with simulations and a dynamic blood phantom experiment. PMID:14759043

  8. Molecular Imaging of Breast Cancer: Present and future directions

    NASA Astrophysics Data System (ADS)

    Alcantara, David; Pernia Leal, Manuel; Garcia, Irene; Garcia-Martin, Maria Luisa

    2014-12-01

    Medical imaging technologies have undergone explosive growth over the past few decades and now play a central role in clinical oncology. But the truly transformative power of imaging in the clinical management of cancer patients lies ahead. Today, imaging is at a crossroads, with molecularly targeted imaging agents expected to broadly expand the capabilities of conventional anatomical imaging methods. Molecular imaging will allow clinicians to not only see where a tumour is located in the body, but also to visualize the expression and activity of specific molecules (e.g. proteases and protein kinases) and biological processes (e.g. apoptosis, angiogenesis, and metastasis) that influence tumour behavior and/or response to therapy. Breast cancer, the most common cancer among women and a research area where our group is actively involved, is a very heterogeneous disease with diverse patterns of development and response to treatment. Hence, molecular imaging is expected to have a major impact on this type of cancer, leading to important improvements in diagnosis, individualized treatment, and drug development, as well as our understanding of how breast cancer arises.

  9. Molecular imaging of breast cancer: present and future directions

    PubMed Central

    Alcantara, David; Leal, Manuel Pernia; García-Bocanegra, Irene; García-Martín, Maria L.

    2014-01-01

    Medical imaging technologies have undergone explosive growth over the past few decades and now play a central role in clinical oncology. But the truly transformative power of imaging in the clinical management of cancer patients lies ahead. Today, imaging is at a crossroads, with molecularly targeted imaging agents expected to broadly expand the capabilities of conventional anatomical imaging methods. Molecular imaging will allow clinicians to not only see where a tumor is located in the body, but also to visualize the expression and activity of specific molecules (e.g., proteases and protein kinases) and biological processes (e.g., apoptosis, angiogenesis, and metastasis) that influence tumor behavior and/or response to therapy. Breast cancer, the most common cancer among women and a research area where our group is actively involved, is a very heterogeneous disease with diverse patterns of development and response to treatment. Hence, molecular imaging is expected to have a major impact on this type of cancer, leading to important improvements in diagnosis, individualized treatment, and drug development, as well as our understanding of how breast cancer arises. PMID:25566530

  10. Direct Penguin Counting Using Unmanned Aerial Vehicle Image

    NASA Astrophysics Data System (ADS)

    Hyun, C. U.; Kim, H. C.; Kim, J. H.; Hong, S. G.

    2015-12-01

    This study presents an application of unmanned aerial vehicle (UAV) images to monitor penguin colony in Baton Peninsula, King George Island, Antarctica. The area around Narębski Point located on the southeast coast of Barton Peninsula was designated as Antarctic Specially Protected Area No. 171 (ASPA 171), and Chinstrap and Gentoo penguins inhabit in this area. The UAV images were acquired in a part of ASPA 171 from four flights in a single day, Jan 18, 2014. About 360 images were mosaicked as an image of about 3 cm spatial resolution and then a subset including representative penguin rookeries was selected. The subset image was segmented based on gradient map of pixel values, and spectral and spatial attributes were assigned to each segment. The object based image analysis (OBIA) was conducted with consideration of spectral attributes including mean and minimum values of each segment and various shape attributes such as area, length, compactness and roundness to detect individual penguin. The segments indicating individual penguin were effectively detected on rookeries with high contrasts in the spectral and shape attributes. The importance of periodic and precise monitoring of penguins has been recognized because variations of their populations reflect environmental changes and disturbance from human activities. Utilization of very high resolution imaging method shown in this study can be applied to other penguin habitats in Antarctica, and the results will be able to support establishing effective environmental management plans.

  11. Future Directions In Image Management: Medical And Practical Considerations

    NASA Astrophysics Data System (ADS)

    Erickson, J. J.; Eikman, E. A.; Shaff, M. I.; James, A. E.

    1983-05-01

    The volume of data produced by new imaging modalities has far outstripped the ability of most departments to effectively utilize the images produced. The problem is further exacerbated by the fact that the diagnostic procedures have become progressively less invasive and traumatic and are being applied to an ever larger patient population. The decrease in cost and the rise in technological capability of computer systems in recent years has provided imaging specialists with the opportunity to create network systems for the storage and recall of diagnostic images. This paper examines the philosophy of image storage from the standpoint of the medical, legal, and practical questions. A proposal is made that not all images are equal and that some deserve to be archived for longer periods than others. The practical problem of using a video display for diagnostic readout, aside from the classical questions of resolution and response time, is discussed. A proposal is also made that two data bases might be created; one which provides rapid access to the clinically relevant images (i.e., the two or three that demonstrate pathology) and one which may require much longer to access, but which contains all the archived data.

  12. Image-Guided Tumor Ablation: Emerging Technologies and Future Directions

    PubMed Central

    McWilliams, Justin P.; Lee, Edward W.; Yamamoto, Shota; Loh, Christopher T.; Kee, Stephen T.

    2010-01-01

    As the trend continues toward the decreased invasiveness of medical procedures, image-guided percutaneous ablation has begun to supplant surgery for the local control of small tumors in the liver, kidney, and lung. New ablation technologies, and refinements of existing technologies, will enable treatment of larger and more complex tumors in these and other organs. At the same time, improvements in intraprocedural imaging promise to improve treatment accuracy and reduce complications. In this review, the latest advancements in clinical and experimental ablation technologies will be summarized, and new applications of image-guided tumor ablation will be discussed. PMID:22550370

  13. New directions in clinical imaging of cortical dysplasias.

    PubMed

    Madan, Neel; Grant, P Ellen

    2009-10-01

    Neuroimaging is essential in the work-up of patients with intractable epilepsy. In pediatric patients with medically refractory epilepsy, cortical dysplasias account for a large percentage of the epileptogenic substrate. Unfortunately, these are also the most subtle lesions to identify. For this reason, there has been ongoing interest in utilizing new advanced magnetic resonance imaging (MRI) techniques to improve the ability to identify, diagnose, characterize, and delineate cortical dysplasias. Technologic gains such as multichannel coils (32 phased array and beyond) and higher field strengths (3T, 7T, and greater) coupled with newer imaging sequences such as arterial spin labeling (ASL), susceptibility weighted imaging (SWI) and diffusion tensor/spectrum imaging (DTI/DSI) are likely to increase yield. Improved MRI techniques coupled with a multimodality approach including magnetoencephalography (MEG), positron emission tomography (PET), and other techniques will increase sensitivity and specificity for identifying cortical dysplasias. PMID:19761449

  14. 12-Month-Old Infants' Perception of Attention Direction in Static Video Images

    ERIC Educational Resources Information Center

    von Hofsten, Claes; Dahlstrom, Emma; Fredriksson, Ylva

    2005-01-01

    Twelve-month-old infants' ability to perceive gaze direction in static video images was investigated. The images showed a woman who performed attention-directing actions by looking or pointing toward 1 of 4 objects positioned in front of her (2 on each side). When the model just pointed at the objects, she looked straight ahead, and when she just…

  15. Functional imaging using the retinal function imager: direct imaging of blood velocity, achieving fluorescein angiography-like images without any contrast agent, qualitative oximetry, and functional metabolic signals.

    PubMed

    Izhaky, David; Nelson, Darin A; Burgansky-Eliash, Zvia; Grinvald, Amiram

    2009-07-01

    The Retinal Function Imager (RFI; Optical Imaging, Rehovot, Israel) is a unique, noninvasive multiparameter functional imaging instrument that directly measures hemodynamic parameters such as retinal blood-flow velocity, oximetric state, and metabolic responses to photic activation. In addition, it allows capillary perfusion mapping without any contrast agent. These parameters of retinal function are degraded by retinal abnormalities. This review delineates the development of these parameters and demonstrates their clinical applicability for noninvasive detection of retinal function in several modalities. The results suggest multiple clinical applications for early diagnosis of retinal diseases and possible critical guidance of their treatment. PMID:19763751

  16. Direct Imaging of Exoplanets Living an Exciting Life

    NASA Astrophysics Data System (ADS)

    Chauvin, G.

    2016-01-01

    With the development of high contrast imaging techniques and instruments, vast efforts have been devoted during the past decades to detect and characterize lighter, cooler and closer companions to nearby stars, and ultimately image new planetary systems. Complementary to other planet-hunting techniques, this approach has opened a new astrophysical window to study the physical properties and the formation mechanisms of brown dwarfs and planets. In this review, I will briefly describe the different observing techniques and strategies used, the main samples of targeted nearby stars, finally the main results obtained so far about exoplanet discoveries characterization of their physical properties, and study of their occurrence and possible formation and evolution mechanisms.

  17. Detecting groundwater flow direction from infrared thermal images

    NASA Astrophysics Data System (ADS)

    Ahmad, Akhundzadah Noor; Saito, Hirotaka; Asada, Kei; Kato, Makoto

    In this study we propose an approach to directly measure temperature changes around the heat source placed in a borehole using an infrared camera for determining groundwater flow direction. A plastic box filled with sands with a cylindrical perforated column placed in middle of the box was used in lab experiments. A heater was inserted in the center of the borehole. To detect the flow direction from the temperature distribution, an infrared camera that was placed face-down at the top of the cylinder (i.e., borehole) was used. COMSOL was used to numerically simulate coupled water flow and heat transfer to evaluate experimental results. Results show that when the flux is in the order of 10-2 to 10-4cm s-1, we can determine the groundwater flow direction because of a skewed temperature distribution due to convective transport of heat.

  18. Fiber optic direct Raman imaging system based on a hollow-core fiber bundle

    NASA Astrophysics Data System (ADS)

    Inoue, S.; Katagiri, T.; Matsuura, Y.

    2015-03-01

    A Raman imaging system which combined a hollow fiber bundle and a direct imaging technique was constructed for high-speed endoscopic Raman imaging. The hollow fiber bundle is fabricated by depositing a silver thin film on the inner surface of pre-drawn glass capillary bundle. It performs as a fiber optic probe which transmits a Raman image with high signal-to-noise ratio because the propagating light is confined into the air core inducing little light scattering. The field of view on the sample is uniformly irradiated by the excitation laser light via the probe. The back-scattered image is collected by the probe and captured directly by an image sensor. A pair of thin film tunable filters is used to select target Raman band. This imaging system enables flexible and high-speed Raman imaging of biological tissues.

  19. Half-time Tc-99m sestamibi imaging with a direct conversion molecular breast imaging system

    PubMed Central

    2014-01-01

    Background In an effort to reduce necessary acquisition time to perform molecular breast imaging (MBI), we compared diagnostic performance of MBI performed with standard 10-min-per-view acquisitions and half-time 5-min-per-view acquisitions, with and without wide beam reconstruction (WBR) processing. Methods Eighty-two bilateral, two-view MBI studies were reviewed. Studies were performed with 300 MBq Tc-99 m sestamibi and a direct conversion molecular breast imaging (DC-MBI) system. Acquisitions were 10 min-per-view; the first half of each was extracted to create 5-min-per-view datasets, and WBR processing was applied. The 10-min-, 5-min-, and 5-min-per-view WBR studies were independently interpreted in a randomized, blinded fashion by two radiologists. Assessments of 1 to 5 were assigned; 4 and 5 were considered test positive. Background parenchymal uptake, lesion type, distribution of non-mass lesions, lesion intensity, and image quality were described. Results Considering detection of all malignant and benign lesions, 5 min-per-view MBI had lower sensitivity (mean of 70% vs. 85% (p ≤ 0.04) for two readers) and lower area under curve (AUC) (mean of 92.7 vs. 99.6, p ≤ 0.01) but had similar specificity (p = 1.0). WBR processing did not alter sensitivity, specificity, or AUC obtained at 5 min-per-view. Overall agreement in final assessment between 5-min-per-view and 10-min-per-view acquisition types was near perfect (κ = 0.82 to 0.89); however, fair to moderate agreement was observed for assessment category 3 (probably benign) (κ = 0.24 to 0.48). Of 33 malignant lesions, 6 (18%) were changed from assessment of 4 or 5 with 10-min-per-view MBI to assessment of 3 with 5-min-per-view MBI. Image quality of 5-min-per-view studies was reduced compared to 10-min-per-view studies for both readers (3.24 vs. 3.98, p < 0.0001 and 3.60 vs. 3.91, p < 0.0001). WBR processing improved image quality for one reader (3.85 vs. 3.24, p < 0

  20. The subjective image quality of direct digital and conventional panoramic radiography.

    PubMed

    Gijbels, F; De Meyer, A M; Bou Serhal, C; Van den Bossche, C; Declerck, J; Persoons, M; Jacobs, R

    2000-09-01

    One of the main advantages of digital imaging is the possibility of altering display options for improved image interpretation. The aim of the present study was to evaluate the subjective image quality of direct digital panoramic images and compare the results with those obtained from conventional images. Furthermore, the effect of various filter settings on image interpretation was assessed. Panoramic images were obtained with three different types of panoramic equipment (one direct digital and two conventional units) from three groups of 54 patients with a natural dentition in all quadrants. The first series of panoramic images consisted of 54 unprocessed digital images; conventional film images (n = 108) comprised the second and third series. A final series consisted of the digital images treated with three different filters ("smoothening," "sharpening," and "contrast enhancement"). All images were scored randomly by four experts in oral radiology on a 4-point rating scale. The results showed a statistically significant difference in scorings between the conventional and digital panoramic units. The main reason for poor image quality appeared to be a combination of blurring and overlapping in the panoramic image. The premolar region in the upper jaw was the region where most additional radiographs were needed. PMID:11000322

  1. Jet Directions in Seyfert Galaxies: Radio Continuum Imaging Data

    NASA Astrophysics Data System (ADS)

    Schmitt, H. R.; Ulvestad, J. S.; Antonucci, R. R. J.; Kinney, A. L.

    2001-02-01

    We present the results of VLA A-array 8.46 GHz continuum imaging of 55 Seyfert galaxies (19 Seyfert 1's and 36 Seyfert 2's). These galaxies are part of a larger sample of 88 Seyfert galaxies, selected from mostly isotropic properties, the flux at 60 μm, and warm infrared 25-60 μm colors. These images are used to study the structure of the radio continuum emission of these galaxies and their position angles, in the case of extended sources. These data, combined with information from broadband B and I observations, have been used to study the orientation of radio jets relative to the plane of their host galaxies (Kinney et al.).

  2. Candidate Gravitational Microlensing Events for Future Direct Lens Imaging

    NASA Astrophysics Data System (ADS)

    Henderson, C. B.; Park, H.; Sumi, T.; Udalski, A.; Gould, A.; Tsapras, Y.; Han, C.; Gaudi, B. S.; Bozza, V.; Abe, F.; Bennett, D. P.; Bond, I. A.; Botzler, C. S.; Freeman, M.; Fukui, A.; Fukunaga, D.; Itow, Y.; Koshimoto, N.; Ling, C. H.; Masuda, K.; Matsubara, Y.; Muraki, Y.; Namba, S.; Ohnishi, K.; Rattenbury, N. J.; Saito, To; Sullivan, D. J.; Suzuki, D.; Sweatman, W. L.; Tristram, P. J.; Tsurumi, N.; Wada, K.; Yamai, N.; Yock, P. C. M.; Yonehara, A.; MOA Collaboration; Szymański, M. K.; Kubiak, M.; Pietrzyński, G.; Soszyński, I.; Skowron, J.; Kozłowski, S.; Poleski, R.; Ulaczyk, K.; Wyrzykowski, Ł.; Pietrukowicz, P.; OGLE Collaboration; Almeida, L. A.; Bos, M.; Choi, J.-Y.; Christie, G. W.; Depoy, D. L.; Dong, S.; Friedmann, M.; Hwang, K.-H.; Jablonski, F.; Jung, Y. K.; Kaspi, S.; Lee, C.-U.; Maoz, D.; McCormick, J.; Moorhouse, D.; Natusch, T.; Ngan, H.; Pogge, R. W.; Shin, I.-G.; Shvartzvald, Y.; Tan, T.-G.; Thornley, G.; Yee, J. C.; μFUN Collaboration; Allan, A.; Bramich, D. M.; Browne, P.; Dominik, M.; Horne, K.; Hundertmark, M.; Figuera Jaimes, R.; Kains, N.; Snodgrass, C.; Steele, I. A.; Street, R. A.; RoboNet Collaboration

    2014-10-01

    The mass of the lenses giving rise to Galactic microlensing events can be constrained by measuring the relative lens-source proper motion and lens flux. The flux of the lens can be separated from that of the source, companions to the source, and unrelated nearby stars with high-resolution images taken when the lens and source are spatially resolved. For typical ground-based adaptive optics (AO) or space-based observations, this requires either inordinately long time baselines or high relative proper motions. We provide a list of microlensing events toward the Galactic bulge with high relative lens-source proper motion that are therefore good candidates for constraining the lens mass with future high-resolution imaging. We investigate all events from 2004 to 2013 that display detectable finite-source effects, a feature that allows us to measure the proper motion. In total, we present 20 events with μ >~ 8 mas yr-1. Of these, 14 were culled from previous analyses while 6 are new, including OGLE-2004-BLG-368, MOA-2005-BLG-36, OGLE-2012-BLG-0211, OGLE-2012-BLG-0456, MOA-2012-BLG-532, and MOA-2013-BLG-029. In lsim12 yr from the time of each event the lens and source of each event will be sufficiently separated for ground-based telescopes with AO systems or space telescopes to resolve each component and further characterize the lens system. Furthermore, for the most recent events, comparison of the lens flux estimates from images taken immediately to those estimated from images taken when the lens and source are resolved can be used to empirically check the robustness of the single-epoch method currently being used to estimate lens masses for many events.

  3. Candidate gravitational microlensing events for future direct lens imaging

    SciTech Connect

    Henderson, C. B.; Gould, A.; Gaudi, B. S.; Park, H.; Han, C.; Sumi, T.; Koshimoto, N.; Udalski, A.; Tsapras, Y.; Bozza, V.; Abe, F.; Fukunaga, D.; Itow, Y.; Masuda, K.; Bennett, D. P.; Bond, I. A.; Ling, C. H.; Botzler, C. S.; Freeman, M.; Fukui, A.; Collaboration: MOA Collaboration; OGLE Collaboration; μFUN Collaboration; RoboNet Collaboration; and others

    2014-10-10

    The mass of the lenses giving rise to Galactic microlensing events can be constrained by measuring the relative lens-source proper motion and lens flux. The flux of the lens can be separated from that of the source, companions to the source, and unrelated nearby stars with high-resolution images taken when the lens and source are spatially resolved. For typical ground-based adaptive optics (AO) or space-based observations, this requires either inordinately long time baselines or high relative proper motions. We provide a list of microlensing events toward the Galactic bulge with high relative lens-source proper motion that are therefore good candidates for constraining the lens mass with future high-resolution imaging. We investigate all events from 2004 to 2013 that display detectable finite-source effects, a feature that allows us to measure the proper motion. In total, we present 20 events with μ ≳ 8 mas yr{sup –1}. Of these, 14 were culled from previous analyses while 6 are new, including OGLE-2004-BLG-368, MOA-2005-BLG-36, OGLE-2012-BLG-0211, OGLE-2012-BLG-0456, MOA-2012-BLG-532, and MOA-2013-BLG-029. In ≲12 yr from the time of each event the lens and source of each event will be sufficiently separated for ground-based telescopes with AO systems or space telescopes to resolve each component and further characterize the lens system. Furthermore, for the most recent events, comparison of the lens flux estimates from images taken immediately to those estimated from images taken when the lens and source are resolved can be used to empirically check the robustness of the single-epoch method currently being used to estimate lens masses for many events.

  4. Cardiac MR imaging: current status and future direction

    PubMed Central

    Van, Tu Anh; Krug, Roland; Hetts, Steven W.; Wilson, Mark W.

    2015-01-01

    Coronary artery disease is currently a worldwide epidemic with increasing impact on healthcare systems. Magnetic resonance imaging (MRI) sequences give complementary information on LV function, regional perfusion, angiogenesis, myocardial viability and orientations of myocytes. T2-weighted short-tau inversion recovery (T2-STIR), fat suppression and black blood sequences have been frequently used for detecting edematous area at risk (AAR) of infarction. T2 mapping, however, indicated that the edematous reaction in acute myocardial infarct (AMI) is not stable and warranted the use of edematous area in evaluating therapies. On the other hand, cine MRI demonstrated reproducible data on LV function in healthy volunteers and LV remodeling in patients. Noninvasive first pass perfusion, using exogenous tracer (gadolinium-based contrast media) and arterial spin labeling MRI, using endogenous tracer (water), are sensitive and useful techniques for evaluating myocardial perfusion and angiogenesis. Recently, new strategies have been developed to quantify myocardial viability using T1-mapping and equilibrium contrast enhanced MR techniques because existing delayed contrast enhancement MRI (DE-MRI) sequences are limited in detecting patchy microinfarct and diffuse fibrosis. These new techniques were successfully used for characterizing diffuse myocardial fibrosis associated with myocarditis, amyloidosis, sarcoidosis heart failure, aortic hypertrophic cardiomyopathy, congenital heart disease, restrictive cardiomyopathy, arrhythmogenic right ventricular dysplasia and hypertension). Diffusion MRI provides information regarding microscopic tissue structure, while diffusion tensor imaging (DTI) helps to characterize the myocardium and monitor the process of LV remodeling after AMI. Novel trends in hybrid imaging, such as cardiac positron emission tomography (PET)/MRI and optical imaging/MRI, are recently under intensive investigation. With the promise of higher spatial

  5. Direct imaging of tunneling from a potential well.

    PubMed

    Tomes, Mathew; Vahala, Kerry J; Carmon, Tal

    2009-10-12

    We experimentally map the wavefunction in the vicinity of a radial potential well. We photograph light intensity near the tunneling region as well as measure the spiraling phase structure via interference with a reference wave. This spiraling phase structure is required for conservation of angular momentum. The experimental image reveals the non-intuitive emission of light from a region in space that is empty of material and relatively far from the device. PMID:20372652

  6. Direct estimation of evoked hemoglobin changes by multimodality fusion imaging

    PubMed Central

    Huppert, Theodore J.; Diamond, Solomon G.; Boas, David A.

    2009-01-01

    In the last two decades, both diffuse optical tomography (DOT) and blood oxygen level dependent (BOLD)-based functional magnetic resonance imaging (fMRI) methods have been developed as noninvasive tools for imaging evoked cerebral hemodynamic changes in studies of brain activity. Although these two technologies measure functional contrast from similar physiological sources, i.e., changes in hemoglobin levels, these two modalities are based on distinct physical and biophysical principles leading to both limitations and strengths to each method. In this work, we describe a unified linear model to combine the complimentary spatial, temporal, and spectroscopic resolutions of concurrently measured optical tomography and fMRI signals. Using numerical simulations, we demonstrate that concurrent optical and BOLD measurements can be used to create cross-calibrated estimates of absolute micromolar deoxyhemoglobin changes. We apply this new analysis tool to experimental data acquired simultaneously with both DOT and BOLD imaging during a motor task, demonstrate the ability to more robustly estimate hemoglobin changes in comparison to DOT alone, and show how this approach can provide cross-calibrated estimates of hemoglobin changes. Using this multimodal method, we estimate the calibration of the 3 tesla BOLD signal to be −0.55% ± 0.40% signal change per micromolar change of deoxyhemoglobin. PMID:19021411

  7. Mapping site-specific endonuclease binding to DNA by direct imaging with AFM

    SciTech Connect

    Allison, D.P.; Thundat, T.; Doktycz, M.J.; Kerper, P.S.; Warmack, R.J.; Modrich, P.; Isfort, R.J.

    1995-12-31

    Physical mapping of DNA can be accomplished by direct AFM imaging of site specific proteins bound to DNA molecules. Using Gln-111, a mutant of EcoRI endonuclease with a specific affinity for EcoRI sites 1,000 times greater than wild type enzyme but with cleavage rate constants reduced by a factor of 10{sup 4}, the authors demonstrate site-specific mapping by direct AFM imaging. Images are presented showing specific-site binding of Gln-111 to plasmids having either one (pBS{sup +}) or two (pMP{sup 32}) EcoRI sites. Identification of the Gln-111/DNA complex is greatly enhanced by biotinylation of the complex followed by reaction with streptavidin gold prior to imaging. Image enhancement coupled with improvements in the preparation techniques for imaging large DNA molecules, such as lambda DNA (47 kb), has the potential to contribute to direct AFM restriction mapping of cosmid-sized genomic DNAs.

  8. Fast multiscale directional filter bank-based speckle mitigation in gallstone ultrasound images.

    PubMed

    Leavline, Epiphany Jebamalar; Sutha, Shunmugam; Singh, Danasingh Asir Antony Gnana

    2014-02-01

    Speckle noise is a multiplicative type of noise commonly seen in medical and remote sensing images. It gives a granular appearance that degrades the quality of the recorded images. These speckle noise components need to be mitigated before the image is used for further processing and analysis. This paper presents a novel approach for removing granular speckle noise in gray scale images. We used an efficient multiscale image representation scheme named fast multiscale directional filter bank (FMDFB) along with simple threshold methods such as Vishushrink for image processing. It is a perfect reconstruction framework that can be used for a wide range of image processing applications because of its directionality and reduced computational complexity. The FMDFB-based speckle mitigation is appealing over other traditional multiscale approaches such as wavelets and Contourlets. Our experimental results show that the despeckling performance of the proposed method outperforms the wavelet and Contourlet-based despeckling methods. PMID:24562027

  9. Exoplanet Direct Imaging: Coronagraph Probe Mission Study EXO-C

    NASA Technical Reports Server (NTRS)

    Stapelfeldt, Karl R.

    2013-01-01

    Flagship mission for spectroscopy of ExoEarths is a long-term priority for space astrophysics (Astro2010). Requires 10(exp 10) contrast at 3 lambda/D separation, ( (is) greater than 10,000 times beyond HST performance) and large telescope (is) greater than 4m aperture. Big step. Mission for spectroscopy of giant planets and imaging of disks requires 10(exp 9) contrast at 3 lambda/D (already demonstrated in lab) and (is) approximately 1.5m telescope. Should be much more affordable, good intermediate step.Various PIs have proposed many versions of the latter mission 17 times since 1999; no unified approach.

  10. Method to directly radiolabel antibodies for diagnostic imaging and therapy

    DOEpatents

    Thakur, Mathew L.

    1994-01-01

    The invention is a novel method and kit for directly radiolabeling proteins such as antibodies or antibody fragments for diagnostic and therapeutic purposes. The method comprises incubating a protein-containing solution with a solution of sodium ascorbate; adding a required quantity of reduced radionuclide to the incubated protein. A kit is also provided wherein the protein and/or reducing agents may be in lyophilized form.

  11. Method to directly radiolabel antibodies for diagnostic imaging and therapy

    DOEpatents

    Thakur, Mathew L.

    1991-01-01

    The invention is a novel method and kit for directly radiolabeling proteins such as antibodies or antibody fragments for diagnostic and therapeutic purposes. The method comprises incubating a protein-containing solution with a solution of sodium ascorbate; adding a required quantity of reduced radionuclide to the incubated protein. A kit is also provided wherein the protein and/or reducing agents may be in lyophilized form.

  12. Band-Limited Masks and Direct Imaging of Exoplanets

    NASA Technical Reports Server (NTRS)

    Kuchner, Marc J.

    2009-01-01

    Band-limited masks have become the baseline design for what is now called "classical TPF" and also the N|RCamcomnagraphonJW8 .This technology remains one of the most promising paths for direct detection ofmxop|anedm and disks. I'll describe some of the latest progress in the implementation of this technique and what we have learned about where it can and can not be effectively applied.

  13. Crosswell Imaging Technology & Advanced DSR Navigation for Horizontal Directional Drilling

    SciTech Connect

    Larry Stolarczyk

    2008-08-08

    The objective of Phase II is to develop and demonstrate real-time measurement-while-drilling (MWD) for guidance and navigation of drill strings during horizontal drilling operations applicable to both short and long holes. The end product of Phase II is a functional drill-string assembly outfitted with a commercial version of Drill String Radar (DSR). Project Objectives Develop and demonstrate a dual-phase methodology of in-seam drilling, imaging, and structure confirmation. This methodology, illustrated in Figure 1, includes: (1) Using RIM to image between drill holes for seam thickness estimates and in-seam structures detection. Completed, February 2005; and (2) Using DSR for real-time MWD guidance and navigation of drillstrings during horizontal drilling operations. Completed, November 2008. As of November 2008, the Phase II portion of Contract DE-FC26-04NT42085 is about 99% complete, including milestones and tasks original outlined as Phase II work. The one percent deficiency results from MSHA-related approvals which have yet to be granted (at the time of reporting). These approvals are pending and are do not negatively impact the scope of work or project objectives.

  14. Direct imaging of macrophage activation during PDT treatment

    NASA Astrophysics Data System (ADS)

    Song, Sheng; Zhou, Feifan; Chen, Wei R.; Xing, Da

    2012-03-01

    Mounting evidence describes a more complex progress of macrophage activation during photodynamic therapy (PDT), which performing distinct immunological functions and different physiologies on surrounding cells and tissues. Macrophage-targeted PDT has been applied in the selective killing of cells involved in inflammation and tumor. We have previously shown that PDT-mediated tumor cells apoptosis can induce a higher level immune response than necrosis, and enhance the macrophage activation. However, the molecular mechanism of macrophage activation during PDT-induced apoptotic cells (AC) still unclear. Here, we use confocal microscopy to image the phagocytosis of tumor cells by macrophages. We also observed that PDT-treated AC can activate Toll-like receptors (TLRs) which are present on macrophages surface. Besides, the increase in nitric oxide (NO) formation in macrophages was detected in real time by a laser scanning microscopy. This study provided more details for understanding the molecular mechanism of the immune response induced by PDT-treated AC.

  15. Friends of Hot Jupiters: Trends in directly imaged companion fraction

    NASA Astrophysics Data System (ADS)

    Ngo, Henry; Knutson, Heather A.; Hinkley, Sasha; Crepp, Justin R.; Bechter, Eric B.; Batygin, Konstantin; Howard, Andrew W.; Johnson, John A.; Morton, Timothy; Muirhead, Philip S.

    2015-08-01

    Although almost half of all nearby solar-like stars are part of multi-star systems, the effect of stellar companions on the formation and evolution of planetary systems is poorly understood. In this study we use adaptive optics imaging to search for bound stellar companions to stars hosting transiting hot Jupiters in order to determine whether or not these companions might have influenced the orbital evolution of these planets. Here we expand on our initial survey and present new observations of 24 hot Jupiter hosts, for a total sample size of 74 systems. The increased survey size allows us to probe the relationship between companion fraction and other properties of these systems, such as planetary spin-orbit misalignment, orbital eccentricities, and stellar effective temperature. We also compare the binary fraction in our sample to that of field stars, and confirm our previous result that hot Jupiter hosts are twice as likely to have stellar companions between 50-2000 AU.

  16. Direct imaging of macrophage activation during PDT treatment

    NASA Astrophysics Data System (ADS)

    Song, Sheng; Zhou, Feifan; Chen, Wei R.; Xing, Da

    2011-11-01

    Mounting evidence describes a more complex progress of macrophage activation during photodynamic therapy (PDT), which performing distinct immunological functions and different physiologies on surrounding cells and tissues. Macrophage-targeted PDT has been applied in the selective killing of cells involved in inflammation and tumor. We have previously shown that PDT-mediated tumor cells apoptosis can induce a higher level immune response than necrosis, and enhance the macrophage activation. However, the molecular mechanism of macrophage activation during PDT-induced apoptotic cells (AC) still unclear. Here, we use confocal microscopy to image the phagocytosis of tumor cells by macrophages. We also observed that PDT-treated AC can activate Toll-like receptors (TLRs) which are present on macrophages surface. Besides, the increase in nitric oxide (NO) formation in macrophages was detected in real time by a laser scanning microscopy. This study provided more details for understanding the molecular mechanism of the immune response induced by PDT-treated AC.

  17. Shallow subsurface imaging of the Piano di Pezza active normal fault (central Italy) by high-resolution refraction and electrical resistivity tomography coupled with time domain electromagnetic data

    NASA Astrophysics Data System (ADS)

    Villani, Fabio; Tulliani, Valerio; Fierro, Elisa; Sapia, Vincenzo; Civico, Riccardo

    2015-04-01

    The Piano di Pezza fault is the north-westernmost segment of the >20 km long Ovindoli-Pezza active normal fault-system (central Italy). Although existing paleoseismic data document high vertical Holocene slip rates (~1 mm/yr) and a remarkable seismogenic potential of this fault, its subsurface setting and Pleistocene cumulative displacement are still poorly known. We investigated for the first time by means of high-resolution seismic and electrical resistivity tomography coupled with time domain electromagnetic (TDEM) measurements the shallow subsurface of a key section of the Piano di Pezza fault. Our surveys cross a ~5 m-high fault scarp that was generated by repeated surface-rupturing earthquakes displacing some Late Holocene alluvial fans. We provide 2-D Vp and resistivity images which clearly show significant details of the fault structure and the geometry of the shallow basin infill material down to 50 m depth. We can estimate the dip (~50°) and the Holocene vertical displacement of the master fault (~10 m). We also recognize in the hangingwall some low-velocity/low-resistivity regions that we relate to packages of colluvial wedges derived from scarp degradation, which may represent the record of several paleo-earthquakes older than the Late Holocene events previously recognized by paleoseismic trenching. Conversely, due to the limited investigation depth of seismic and electrical tomography, the estimation of the cumulative amount of Pleistocene throw is hampered. Therefore, to increase the depth of investigation, we performed 7 TDEM measurements along the electrical profile using a 50 m loop size both in central and offset configuration. The recovered 1-D resistivity models show a good match with 2-D resistivity images in the near surface. Moreover, TDEM inversion results indicate that in the hangingwall, ~200 m away from the surface fault trace, the carbonate pre-Quaternary basement may be found at ~90-100 m depth. The combined approach of electrical and

  18. Direct Imaging Search for Extrasolar Planets in the Pleiades

    NASA Technical Reports Server (NTRS)

    Yamamoto, Kodai; Matsuo, Taro; Shibai, Hiroshi; Itoh, Yoichi; Konishi, Mihokko; Sudo, Jun; Tanii, Ryoko; Fukagawa, Misato; Sumi, Takahiro; Kudo, Tomoyuki; Hashimoto, Jun; Kusakabe, Nobuhiko; Abe, Lyn; Brandner, Wolfgang; Brandt, Timothy D.; Carson, Joseph; Currie, Thayne; Egner, Sebastian E,; Feldt, Markus; Goto, Miwa; Grady, Carol; Guyon, Olivier; Hayano, Yutaka; McElwain, Mike; Serabyn, Eugene

    2013-01-01

    We carried out an imaging survey for extrasolar planets around stars in the Pleiades (125 Myr, 135 pc) in the H and K(sub S) bands using HiCIAO combined with adaptive optics, AO188, on the Subaru telescope. We found 13 companion candidates fainter than 14.5 mag in the H band around 9 stars. Five of these 13 were confirmed to be background stars by measurement of their proper motion. One was not found in the second epoch observation, and thus was not a background or companion object. One had multi-epoch images, but the precision of its proper motion was not sufficient to conclude whether it was a background object. Four other candidates are waiting for second-epoch observations to determine their proper motion. Finally, the remaining two were confirmed to be 60 M(sub J) brown dwarf companions orbiting around HD 23514 (G0) and HII 1348 (K5), respectively, as had been reported in previous studies. In our observations, the average detection limit for a point source was 20.3 mag in the H band beyond 1.'' 5 from the central star. On the basis of this detection limit, we calculated the detection efficiency to be 90% for a planet with 6 to 12 Jovian masses and a semi-major axis of 50–1000 AU. For this reason we extrapolated the distribution of the planet mass and the semi-major axis derived from radial velocity observations, and adopted the planet evolution model Baraffe et al. (2003, A&A, 402, 701). Since there was no detection of a planet, we estimated the frequency of such planets to be less than 17.9% (2 sigma) around one star of the Pleiades cluster.

  19. Recent developments in the direct-current geoelectrical imaging method

    NASA Astrophysics Data System (ADS)

    Loke, M. H.; Chambers, J. E.; Rucker, D. F.; Kuras, O.; Wilkinson, P. B.

    2013-08-01

    There have been major improvements in instrumentation, field survey design and data inversion techniques for the geoelectrical method over the past 25 years. Multi-electrode and multi-channel systems have made it possible to conduct large 2-D, 3-D and even 4-D surveys efficiently to resolve complex geological structures that were not possible with traditional 1-D surveys. Continued developments in computer technology, as well as fast data inversion techniques and software, have made it possible to carry out the interpretation on commonly available microcomputers. Multi-dimensional geoelectrical surveys are now widely used in environmental, engineering, hydrological and mining applications. 3-D surveys play an increasingly important role in very complex areas where 2-D models suffer from artifacts due to off-line structures. Large areas on land and water can be surveyed rapidly with computerized dynamic towed resistivity acquisition systems. The use of existing metallic wells as long electrodes has improved the detection of targets in areas where they are masked by subsurface infrastructure. A number of PC controlled monitoring systems are also available to measure and detect temporal changes in the subsurface. There have been significant advancements in techniques to automatically generate optimized electrodes array configurations that have better resolution and depth of investigation than traditional arrays. Other areas of active development include the translation of electrical values into geological parameters such as clay and moisture content, new types of sensors, estimation of fluid or ground movement from time-lapse images and joint inversion techniques. In this paper, we investigate the recent developments in geoelectrical imaging and provide a brief look into the future of where the science may be heading.

  20. Direct Image-To Registration Using Mobile Sensor Data

    NASA Astrophysics Data System (ADS)

    Kehl, C.; Buckley, S. J.; Gawthorpe, R. L.; Viola, I.; Howell, J. A.

    2016-06-01

    Adding supplementary texture and 2D image-based annotations to 3D surface models is a useful next step for domain specialists to make use of photorealistic products of laser scanning and photogrammetry. This requires a registration between the new camera imagery and the model geometry to be solved, which can be a time-consuming task without appropriate automation. The increasing availability of photorealistic models, coupled with the proliferation of mobile devices, gives users the possibility to complement their models in real time. Modern mobile devices deliver digital photographs of increasing quality, as well as on-board sensor data, which can be used as input for practical and automatic camera registration procedures. Their familiar user interface also improves manual registration procedures. This paper introduces a fully automatic pose estimation method using the on-board sensor data for initial exterior orientation, and feature matching between an acquired photograph and a synthesised rendering of the orientated 3D scene as input for fine alignment. The paper also introduces a user-friendly manual camera registration- and pose estimation interface for mobile devices, based on existing surface geometry and numerical optimisation methods. The article further assesses the automatic algorithm's accuracy compared to traditional methods, and the impact of computational- and environmental parameters. Experiments using urban and geological case studies show a significant sensitivity of the automatic procedure to the quality of the initial mobile sensor values. Changing natural lighting conditions remain a challenge for automatic pose estimation techniques, although progress is presented here. Finally, the automatically-registered mobile images are used as the basis for adding user annotations to the input textured model.

  1. Direction and movement angular velocity determining of cloudiness with panoramic images of the sky

    NASA Astrophysics Data System (ADS)

    Galileiskii, Viktor P.; Elizarov, Alexey I.; Kokarev, Dmitrii V.; Morozov, Aleksandr M.

    2014-11-01

    This article gives a short overview to method of direction determining and visible angular velocity of movement determining of cloudiness based on set of panoramic images of cloudy sky, obtained by "Fisheye" wide-angle lens.

  2. [The hyperspectral camera side-scan geometric imaging in any direction considering the spectral mixing].

    PubMed

    Wang, Shu-Min; Zhang, Ai-Wu; Hu, Shao-Xing; Sun, Wei-Dong

    2014-07-01

    In order to correct the image distortion in the hyperspectral camera side-scan geometric Imaging, the image pixel geo-referenced algorithm was deduced in detail in the present paper, which is suitable to the linear push-broom camera side-scan imaging on the ground in any direction. It takes the orientation of objects in the navigation coordinates system into account. Combined with the ground sampling distance of geo-referenced image and the area of push broom imaging, the general process of geo-referenced image divided into grids is also presented. The new image rows and columns will be got through the geo-referenced image area dividing the ground sampling distance. Considering the error produced by round rule in the pixel grids generated progress, and the spectral mixing problem caused by traditional direct spectral sampling method in the process of image correction, the improved spectral sampling method based on the weighted fusion method was proposed. It takes the area proportion of adjacent pixels in the new generated pixel as coefficient and then the coefficients are normalized to avoid the spectral overflow. So the new generated pixel is combined with the geo-referenced adjacent pixels spectral. Finally the amounts of push-broom imaging experiments were taken on the ground, and the distortion images were corrected according to the algorithm proposed above. The results show that the linear image distortion correction algorithm is valid and robust. At the same time, multiple samples were selected in the corrected images to verify the spectral data. The results indicate that the improved spectral sampling method is better than the direct spectral sampling algorithm. It provides reference for the application of similar productions on the ground. PMID:25269321

  3. Confirmation of the Planet around HD 95086 by Direct Imaging

    NASA Astrophysics Data System (ADS)

    Rameau, J.; Chauvin, G.; Lagrange, A.-M.; Meshkat, T.; Boccaletti, A.; Quanz, S. P.; Currie, T.; Mawet, D.; Girard, J. H.; Bonnefoy, M.; Kenworthy, M.

    2013-12-01

    VLT/NaCo angular differential imaging at L' (3.8 μm) revealed a probable giant planet comoving with the young and early-type HD 95086, also known to harbor an extended debris disk. The discovery was based on the proper motion analysis of two datasets spanning 15 months. However, the second dataset suffered from bad atmospheric conditions, which limited the significance of the re-detection at the 3σ level. In this Letter, we report new VLT/NaCo observations of HD 95086 obtained on 2013 June 26 and 27 at L' to recover the planet candidate. We unambiguously re-detect the companion HD 95086 b with multiple independent pipelines at a signal-to-noise ratio greater than or equal to 5. Combined with previously reported measurements, our astrometry decisively shows that the planet is comoving with HD 95086 and inconsistent with a background object. With a revised mass of 5 ± 2 Jupiter masses, estimated from its L' photometry and "hot-start" models at 17 ± 4 Myr, HD 95086 b becomes a new benchmark for further physical and orbital characterization of young giant planets. Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere, Chile, under programs number 291.C-5023.

  4. CONFIRMATION OF THE PLANET AROUND HD 95086 BY DIRECT IMAGING

    SciTech Connect

    Rameau, J.; Chauvin, G.; Lagrange, A.-M.; Boccaletti, A.; Quanz, S. P.; Currie, T.; Mawet, D.; Girard, J. H.; Bonnefoy, M.

    2013-12-20

    VLT/NaCo angular differential imaging at L' (3.8 μm) revealed a probable giant planet comoving with the young and early-type HD 95086, also known to harbor an extended debris disk. The discovery was based on the proper motion analysis of two datasets spanning 15 months. However, the second dataset suffered from bad atmospheric conditions, which limited the significance of the re-detection at the 3σ level. In this Letter, we report new VLT/NaCo observations of HD 95086 obtained on 2013 June 26 and 27 at L' to recover the planet candidate. We unambiguously re-detect the companion HD 95086 b with multiple independent pipelines at a signal-to-noise ratio greater than or equal to 5. Combined with previously reported measurements, our astrometry decisively shows that the planet is comoving with HD 95086 and inconsistent with a background object. With a revised mass of 5 ± 2 Jupiter masses, estimated from its L' photometry and ''hot-start'' models at 17 ± 4 Myr, HD 95086 b becomes a new benchmark for further physical and orbital characterization of young giant planets.

  5. Direct fusion of geostationary meteorological satellite visible and infrared images based on thermal physical properties.

    PubMed

    Han, Lei; Wulie, Buzha; Yang, Yiling; Wang, Hongqing

    2015-01-01

    This study investigated a novel method of fusing visible (VIS) and infrared (IR) images with the major objective of obtaining higher-resolution IR images. Most existing image fusion methods focus only on visual performance and many fail to consider the thermal physical properties of the IR images, leading to spectral distortion in the fused image. In this study, we use the IR thermal physical property to correct the VIS image directly. Specifically, the Stefan-Boltzmann Law is used as a strong constraint to modulate the VIS image, such that the fused result shows a similar level of regional thermal energy as the original IR image, while preserving the high-resolution structural features from the VIS image. This method is an improvement over our previous study, which required VIS-IR multi-wavelet fusion before the same correction method was applied. The results of experiments show that applying this correction to the VIS image directly without multi-resolution analysis (MRA) processing achieves similar results, but is considerably more computationally efficient, thereby providing a new perspective on VIS and IR image fusion. PMID:25569749

  6. Direct atomic resolution imaging of dislocation core structures in a 300 kV stem

    SciTech Connect

    McGibbon, A.J.; Pennycook, S.J.

    1995-05-01

    By employing the incoherent imaging technique of Z-contrast imaging in a 300kV STEM, the authors show that it is possible to provide directly interpretable, atomic resolution images of the sublattice in compound semiconductors. Using this approach, analysis of dislocations at an interface in the CdTe(001)/GaAs(001) system reveals unexpected core structures at Lomer dislocations.

  7. a Systematic Comparison of Direct and Image-Based Georeferencing in Challenging Urban Areas

    NASA Astrophysics Data System (ADS)

    Cavegn, S.; Nebiker, S.; Haala, N.

    2016-06-01

    Image-based mobile mapping systems enable an efficient acquisition of georeferenced image sequences, which can be used for geo-data capture in subsequent steps. In order to provide accurate measurements in a given reference frame while e.g. aiming at high fidelity 3D urban models, high quality georeferencing of the captured multi-view image sequences is required. Moreover, sub-pixel accurate orientations of these highly redundant image sequences are needed in order to optimally perform steps like dense multi-image matching as a prerequisite for 3D point cloud and mesh generation. While direct georeferencing of image-based mobile mapping data performs well in open areas, poor GNSS coverage in urban canyons aggravates fulfilling these high accuracy requirements, even with high-grade inertial navigation equipment. Hence, we conducted comprehensive investigations aiming at assessing the quality of directly georeferenced sensor orientations as well as the expected improvement by image-based georeferencing in a challenging urban environment. Our study repeatedly delivered mean trajectory deviations of up to 80 cm. By performing image-based georeferencing using bundle adjustment for a limited set of cameras and a limited number of ground control points, mean check point residuals could be lowered from approx. 40 cm to 4 cm. Furthermore, we showed that largely automated image-based georeferencing is capable of detecting and compensating discontinuities in directly georeferenced trajectories.

  8. Direct and inverse methods for ocean-wave imaging by SAR

    NASA Astrophysics Data System (ADS)

    Rotheram, S.; Macklin, J. T.

    1984-08-01

    The direct and inverse problems for ocean-wave imaging by SAR for the image and its power spectrum are discussed. The direct problem is reasonably well understood, but the inverse methods are not complete or optimum. However, they represent the first steps in the development of such methods, and they confirm aspects of imaging theory. Other aspects, particularly for the power spectrum, remain to be completed. Once this is done, optimum methods could be developed using Bacchus-Gilbert theory to provide the required tradeoff between resolution and speckle.

  9. Directly imaging steeply-dipping fault zones in geothermal fields with multicomponent seismic data

    DOE PAGESBeta

    Chen, Ting; Huang, Lianjie

    2015-07-30

    For characterizing geothermal systems, it is important to have clear images of steeply-dipping fault zones because they may confine the boundaries of geothermal reservoirs and influence hydrothermal flow. Elastic reverse-time migration (ERTM) is the most promising tool for subsurface imaging with multicomponent seismic data. However, conventional ERTM usually generates significant artifacts caused by the cross correlation of undesired wavefields and the polarity reversal of shear waves. In addition, it is difficult for conventional ERTM to directly image steeply-dipping fault zones. We develop a new ERTM imaging method in this paper to reduce these artifacts and directly image steeply-dipping fault zones.more » In our new ERTM method, forward-propagated source wavefields and backward-propagated receiver wavefields are decomposed into compressional (P) and shear (S) components. Furthermore, each component of these wavefields is separated into left- and right-going, or downgoing and upgoing waves. The cross correlation imaging condition is applied to the separated wavefields along opposite propagation directions. For converted waves (P-to-S or S-to-P), the polarity correction is applied to the separated wavefields based on the analysis of Poynting vectors. Numerical imaging examples of synthetic seismic data demonstrate that our new ERTM method produces high-resolution images of steeply-dipping fault zones.« less

  10. Directly imaging steeply-dipping fault zones in geothermal fields with multicomponent seismic data

    SciTech Connect

    Chen, Ting; Huang, Lianjie

    2015-07-30

    For characterizing geothermal systems, it is important to have clear images of steeply-dipping fault zones because they may confine the boundaries of geothermal reservoirs and influence hydrothermal flow. Elastic reverse-time migration (ERTM) is the most promising tool for subsurface imaging with multicomponent seismic data. However, conventional ERTM usually generates significant artifacts caused by the cross correlation of undesired wavefields and the polarity reversal of shear waves. In addition, it is difficult for conventional ERTM to directly image steeply-dipping fault zones. We develop a new ERTM imaging method in this paper to reduce these artifacts and directly image steeply-dipping fault zones. In our new ERTM method, forward-propagated source wavefields and backward-propagated receiver wavefields are decomposed into compressional (P) and shear (S) components. Furthermore, each component of these wavefields is separated into left- and right-going, or downgoing and upgoing waves. The cross correlation imaging condition is applied to the separated wavefields along opposite propagation directions. For converted waves (P-to-S or S-to-P), the polarity correction is applied to the separated wavefields based on the analysis of Poynting vectors. Numerical imaging examples of synthetic seismic data demonstrate that our new ERTM method produces high-resolution images of steeply-dipping fault zones.

  11. Decision net, directed graph, and neural net processing of imaging spectrometer data

    NASA Technical Reports Server (NTRS)

    Casasent, David; Liu, Shiaw-Dong; Yoneyama, Hideyuki; Barnard, Etienne

    1989-01-01

    A decision-net solution involving a novel hierarchical classifier and a set of multiple directed graphs, as well as a neural-net solution, are respectively presented for large-class problem and mixture problem treatments of imaging spectrometer data. The clustering method for hierarchical classifier design, when used with multiple directed graphs, yields an efficient decision net. New directed-graph rules for reducing local maxima as well as the number of perturbations required, and the new starting-node rules for extending the reachability and reducing the search time of the graphs, are noted to yield superior results, as indicated by an illustrative 500-class imaging spectrometer problem.

  12. A Sphere Phantom Approach to Measure Directional Modulation Transfer Functions for Tomosynthesis Imaging Systems.

    PubMed

    Lee, Changwoo; Baek, Jongduk

    2016-03-01

    We propose a sphere phantom approach to measure spatially varying directional modulation transfer functions (MTFs) for tomosynthesis imaging systems. Since the reconstructed tomosynthesis images contain significant artifacts, traditional background detrending techniques may not be effective to estimate the background trends accurately, which is essential to acquire sphere only data. A background detrending technique optimized for local volumes with different cone angles is presented. To measure directional MTFs, we calculate plane integrals of ideal sphere phantom and sphere only data. To minimize the effects of the high level of noise in tomosynthesis images, Richardson-Lucy deconvolution with Tikhonov-Miller is used to estimate directional plane spread function (PlSF). Then, directional MTFs are calculated by taking the modulus of the Fourier transform of the directional PlSFs. The measured directional MTFs are compared with the ideal directional MTFs calculated from a simulated point object. Our results show that the proposed method reliably measures directional MTFs along any desired directions, especially near low frequency regions. PMID:26571519

  13. Direct method of three-dimensional imaging using the multiple-wavelength range-gated active imaging principle.

    PubMed

    Matwyschuk, Alexis

    2016-05-10

    The tomography executed with mono-wavelength active imaging systems uses the recording of several images to restore a three-dimensional (3D) scene. Thus, in order to show the depth in the scene, a different color is attributed to each recorded image. Therefore, the 3D restoration depends on the video frame rate of the camera. By using a multiple-wavelength range-gated active imaging system, it is possible to restore the 3D scene directly in a single image at the moment of recording with a video camera. Each emitted light pulse with a different wavelength corresponds to a visualized zone at a different distance in the scene. The camera shutter opens just once during the emission of light pulses with the different wavelengths. Thus, the restoration can be executed in real time with regard to the video frame rate of the camera. From an analytical model and from a graphical approach, we demonstrated the feasibility of this new method of 3D restoration. The non-overlapping conditions between two consecutive visualized zones are analyzed. The experimental test results confirm these different conditions and validate the theoretical principle to directly restore the 3D scene in a color image with a multiple-wavelength laser source, an RGB filter, and a triggerable intensified camera. PMID:27168293

  14. Monte Carlo feasibility study for image guided surgery: from direct beta minus detection to Cerenkov luminescence imaging

    NASA Astrophysics Data System (ADS)

    Gigliotti, C. R.; Altabella, L.; Boschi, F.; Spinelli, A. E.

    2016-07-01

    The goal of this work is to compare the performances of different beta minus detection strategies for image guided surgery or ex vivo tissue analysis. In particular we investigated Cerenkov luminescence imaging (CLI) with and without the use of a radiator, direct and indirect beta detection and bremsstrahlung imaging using beta emitters commonly employed in Nuclear Medicine. Monte Carlo simulations were implemented using the GAMOS plug-in for GEANT4 considering a slab of muscle and a radioactive source (32P or 90Y) placed at 0.5 mm depth. We estimated the gain that can be obtained in terms of produced photons using different materials placed on the slab used as Cerenkov radiators, we then focused on the number of exiting photons and their spatial distribution for the different strategies. The use of radiator to enhance Cerenkov signal reduces the spatial resolution because of the increased optical spread. We found that direct beta detection and CLI are best approaches in term of resolution while the use of a thin scintillator increases the signal but the spatial resolution is degraded. Bremsstrahlung presents lower signal and it does not represent the best choice for image guided surgery. CLI represents a more flexible approach for image guided surgery using or ex vivo tissue analysis using beta-emitter imaging.

  15. The Impact of Transiting Planet Science on the Next Generation of Direct-Imaging Planet Searches

    NASA Astrophysics Data System (ADS)

    Carson, Joseph C.

    2009-02-01

    Within the next five years, a number of direct-imaging planet search instruments, like the VLT SPHERE instrument, will be coming online. To successfully carry out their programs, these instruments will rely heavily on a-priori information on planet composition, atmosphere, and evolution. Transiting planet surveys, while covering a different semi-major axis regime, have the potential to provide critical foundations for these next-generation surveys. For example, improved information on planetary evolutionary tracks may significantly impact the insights that can be drawn from direct-imaging statistical data. Other high-impact results from transiting planet science include information on mass-to-radius relationships as well as atmospheric absorption bands. The marriage of transiting planet and direct-imaging results may eventually give us the first complete picture of planet migration, multiplicity, and general evolution.

  16. Vesicorectal fistula detected on direct radionuclide cystography--importance of fecal matter imaging.

    PubMed

    Aghaei, Atena; Sadeghi, Ramin; Saeedi, Parisa

    2014-01-01

    We report an 11 year old male patient with the history of imperforate anus, which was repaired surgically 4 years ago. He has been complaining of intermittent passing of urine into the rectum recently. The vesicorectal fistula in this patient was proven by imaging of the fecal matter post direct radionuclide cystography study. Our case showed that nuclear medicine imaging can be extended to unanimated objects such as patients' excrements or fluids with important diagnostic yields. PMID:24610652

  17. Direct wavefront sensing for high-resolution in vivo imaging in scattering tissue

    PubMed Central

    Wang, Kai; Sun, Wenzhi; Richie, Christopher T.; Harvey, Brandon K.; Betzig, Eric; Ji, Na

    2015-01-01

    Adaptive optics by direct imaging of the wavefront distortions of a laser-induced guide star has long been used in astronomy, and more recently in microscopy to compensate for aberrations in transparent specimens. Here we extend this approach to tissues that strongly scatter visible light by exploiting the reduced scattering of near-infrared guide stars. The method enables in vivo two-photon morphological and functional imaging down to 700 μm inside the mouse brain. PMID:26073070

  18. Direct nanoscale imaging of ballistic and diffusive thermal transport in graphene nanostructures.

    PubMed

    Pumarol, Manuel E; Rosamond, Mark C; Tovee, Peter; Petty, Michael C; Zeze, Dagou A; Falko, Vladimir; Kolosov, Oleg V

    2012-06-13

    We report direct imaging of nanoscale thermal transport in single and few-layer graphene with approximately 50 nm lateral resolution using high vacuum scanning thermal microscopy. We observed increased heat transport in suspended graphene where heat is conducted by ballistic phonons, compared to adjacent areas of supported graphene, and observed decreasing thermal conductance of supported graphene with increased layer number. Our nanothermal images suggest a mean-free-path of thermal phonons in supported graphene below 100 nm. PMID:22524441

  19. The Circumstellar Imager: Direct detection of extra-solar planetary systems

    NASA Technical Reports Server (NTRS)

    Ftaclas, Christ; Nonnenmacher, Andreas L.; Terrile, Richard J.; Pravdo, Steven H.; Gatewood, George D.; Levy, Eugene

    1994-01-01

    The Astrometric Imaging Telescope (AIT) is designed to probe the circumstellar environment by both direct imaging and indirect astrometric measurements. The Circumstellar Imager (CI) is a coronagraphic camera and is the direct imaging component of the AIT. The CI is designed to obtain high-sensitivity images of the circumstellar region. It provides crucial non-inferential information relating to the frequency, origin, and evolution of planetary systems and all forms of circumstellar matter. Such imaging is usually limited by the scattered and diffracted light halos of the star itself, which are greatly suppressed in the CI by mating a novel high-efficiency coronagraph with a phase-compensated optical system. For faint point sources in the circumstellar region, the CI will have a sensitivity in excess of 5 magnitudes fainter than the as-designed Hubble Space Telescope (HST). Laboratory data are shown for the coronagraph, which, in a diffraction-limited environment, is capable of suppressing the stellar diffraction sidelobes by several orders of magnitude without significant sacrifice of field of view. In order to realize the high rejection levels inherent in the coronagraph design, it is necessary to limit scatter in the optical systems, imposing a mid-spatial frequency figure error requirement an order of magnitude smaller than that of the HST. Experimental data directed toward meeting this requirement are also shown.

  20. A Molecular Imaging Paradigm to Rapidly Profile Response to Angiogenesis-directed Therapy in Small Animals

    PubMed Central

    Virostko, John; Xie, Jingping; Hallahan, Dennis E.; Arteaga, Carlos L.; Gore, John C.; Manning, H. Charles

    2009-01-01

    Purpose The development of novel angiogenesis-directed therapeutics is hampered by the lack of non-invasive imaging metrics capable of assessing treatment response. We report the development and validation of a novel molecular imaging paradigm to rapidly assess response to angiogenesis-directed therapeutics in preclinical animal models. Procedures A monoclonal antibody-based optical imaging probe targeting vascular endothelial growth factor receptor-2 (VEGFR2) expression was synthesized and evaluated in vitro and in vivo via multispectral fluorescence imaging. Results The optical imaging agent demonstrated specificity for the target receptor in cultured endothelial cells and in vivo. The agent exhibited significant accumulation within 4T1 xenograft tumors. Mice bearing 4T1 xenografts and treated with sunitinib exhibited both tumor growth arrest and decreased accumulation of NIR800-αVEGFR2ab compared to untreated cohorts (p=0.0021). Conclusions Molecular imaging of VEGFR2 expression is a promising non-invasive biomarker for assessing angiogenesis and evaluating the efficacy of angiogenesis-directed therapies. PMID:19130143

  1. Determination of the Hubble Space Telescope effective conic-constant error from direct image measurements.

    PubMed

    Meinel, A B; Meinel, M P; Schulte, D H

    1993-04-01

    Direct measurement of discernible features in the Hubble Space Telescope (HST) imagery has enabled a self-consistent determination to be made of the effective conic constant of HST images taken with planetary camera 6 (PC-6) of the wide field and planetary camera. Before being corrected for the contribution from PC-6, the conic constant is - 1.01429 +/- 0.0002. The correction for PC-6 is less accurately determined but probably lies between -0.0002 and 0.0004. As a result the HST optics are characterized best by a conic constant of - 1.0140 +/- 0.0003 as obtained from direct image measurements. PMID:20820304

  2. Multisensor Super Resolution Using Directionally-Adaptive Regularization for UAV Images.

    PubMed

    Kang, Wonseok; Yu, Soohwan; Ko, Seungyong; Paik, Joonki

    2015-01-01

    In various unmanned aerial vehicle (UAV) imaging applications, the multisensor super-resolution (SR) technique has become a chronic problem and attracted increasing attention. Multisensor SR algorithms utilize multispectral low-resolution (LR) images to make a higher resolution (HR) image to improve the performance of the UAV imaging system. The primary objective of the paper is to develop a multisensor SR method based on the existing multispectral imaging framework instead of using additional sensors. In order to restore image details without noise amplification or unnatural post-processing artifacts, this paper presents an improved regularized SR algorithm by combining the directionally-adaptive constraints and multiscale non-local means (NLM) filter. As a result, the proposed method can overcome the physical limitation of multispectral sensors by estimating the color HR image from a set of multispectral LR images using intensity-hue-saturation (IHS) image fusion. Experimental results show that the proposed method provides better SR results than existing state-of-the-art SR methods in the sense of objective measures. PMID:26007744

  3. Fluorescence guided lymph node biopsy in large animals using direct image projection device

    NASA Astrophysics Data System (ADS)

    Ringhausen, Elizabeth; Wang, Tylon; Pitts, Jonathan; Akers, Walter J.

    2016-03-01

    The use of fluorescence imaging for aiding oncologic surgery is a fast growing field in biomedical imaging, revolutionizing open and minimally invasive surgery practices. We have designed, constructed, and tested a system for fluorescence image acquisition and direct display on the surgical field for fluorescence guided surgery. The system uses a near-infrared sensitive CMOS camera for image acquisition, a near-infra LED light source for excitation, and DLP digital projector for projection of fluorescence image data onto the operating field in real time. Instrument control was implemented in Matlab for image capture, processing of acquired data and alignment of image parameters with the projected pattern. Accuracy of alignment was evaluated statistically to demonstrate sensitivity to small objects and alignment throughout the imaging field. After verification of accurate alignment, feasibility for clinical application was demonstrated in large animal models of sentinel lymph node biopsy. Indocyanine green was injected subcutaneously in Yorkshire pigs at various locations to model sentinel lymph node biopsy in gynecologic cancers, head and neck cancer, and melanoma. Fluorescence was detected by the camera system during operations and projected onto the imaging field, accurately identifying tissues containing the fluorescent tracer at up to 15 frames per second. Fluorescence information was projected as binary green regions after thresholding and denoising raw intensity data. Promising results with this initial clinical scale prototype provided encouraging results for the feasibility of optical projection of acquired luminescence during open oncologic surgeries.

  4. A multiscale contrast direction adaptation approach for the fusion of multispectral and multifocus infrared images

    NASA Astrophysics Data System (ADS)

    Karali, A. O.; Cakir, Serdar; Aytaç, Tayfun

    2015-10-01

    Infrared (IR) cameras are widely used in latest surveillance systems because spectral characteristics of objects provide valuable information for object detection and identification. To assist the surveillance system operator and automatic image processing tasks, fusing images in IR band is proposed as a solution to increase situational awareness and different fusion techniques are developed for this purpose. Proposed techniques are generally developed for specific scenarios because image content may vary dramatically depending on the spectral range, the optical properties of the cameras, the spectral characteristics of the scene, and the spatial resolution of the interested targets in the scene. A general purpose IR image fusion technique that is suitable for real-time applications is proposed. The proposed technique can support different scenarios by applying a multiscale detail detection and can be applied to images captured from different spectral regions of the spectrum by adaptively adjusting the contrast direction through cross checking between the source images. The feasibility of the proposed algorithm is demonstrated on registered multi-spectral and multi-focus IR images. Fusion results are presented and the performance of the proposed technique is compared with the baseline fusion methods through objective and subjective tests. The technique outperforms baseline methods in the subjective tests and provide promising results in objective quality metrics with an acceptable computational load. Besides, the proposed technique preserves object details and prevents undesired artifacts better than the baseline techniques in the image fusion scenario that contains four source images.

  5. Multisensor Super Resolution Using Directionally-Adaptive Regularization for UAV Images

    PubMed Central

    Kang, Wonseok; Yu, Soohwan; Ko, Seungyong; Paik, Joonki

    2015-01-01

    In various unmanned aerial vehicle (UAV) imaging applications, the multisensor super-resolution (SR) technique has become a chronic problem and attracted increasing attention. Multisensor SR algorithms utilize multispectral low-resolution (LR) images to make a higher resolution (HR) image to improve the performance of the UAV imaging system. The primary objective of the paper is to develop a multisensor SR method based on the existing multispectral imaging framework instead of using additional sensors. In order to restore image details without noise amplification or unnatural post-processing artifacts, this paper presents an improved regularized SR algorithm by combining the directionally-adaptive constraints and multiscale non-local means (NLM) filter. As a result, the proposed method can overcome the physical limitation of multispectral sensors by estimating the color HR image from a set of multispectral LR images using intensity-hue-saturation (IHS) image fusion. Experimental results show that the proposed method provides better SR results than existing state-of-the-art SR methods in the sense of objective measures. PMID:26007744

  6. Experimental demonstration of an adaptive architecture for direct spectral imaging classification.

    PubMed

    Dunlop-Gray, Matthew; Poon, Phillip K; Golish, Dathon; Vera, Esteban; Gehm, Michael E

    2016-08-01

    Spectral imaging is a powerful tool for providing in situ material classification across a spatial scene. Typically, spectral imaging analyses are interested in classification, though often the classification is performed only after reconstruction of the spectral datacube. We present a computational spectral imaging system, the Adaptive Feature-Specific Spectral Imaging Classifier (AFSSI-C), which yields direct classification across the spatial scene without reconstruction of the source datacube. With a dual disperser architecture and a programmable spatial light modulator, the AFSSI-C measures specific projections of the spectral datacube which are generated by an adaptive Bayesian classification and feature design framework. We experimentally demonstrate multiple order-of-magnitude improvement of classification accuracy in low signal-to-noise (SNR) environments when compared to legacy spectral imaging systems. PMID:27505794

  7. Full-direct method for imaging pharmacokinetic parameters in dynamic fluorescence molecular tomography

    NASA Astrophysics Data System (ADS)

    Zhang, Guanglei; Pu, Huangsheng; He, Wei; Liu, Fei; Luo, Jianwen; Bai, Jing

    2015-02-01

    Images of pharmacokinetic parameters (also known as parametric images) in dynamic fluorescence molecular tomography (FMT) can provide three-dimensional metabolic information for biological studies and drug development. However, the ill-posed nature of FMT and the high temporal variation of fluorophore concentration together make it difficult to obtain accurate parametric images in small animals in vivo. In this letter, we present a method to directly reconstruct the parametric images from the boundary measurements based on hybrid FMT/X-ray computed tomography (XCT) system. This method can not only utilize structural priors obtained from the XCT system to mitigate the ill-posedness of FMT but also make full use of the temporal correlations of boundary measurements to model the high temporal variation of fluorophore concentration. The results of numerical simulation and mouse experiment demonstrate that the proposed method leads to significant improvements in the reconstruction quality of parametric images.

  8. Full-direct method for imaging pharmacokinetic parameters in dynamic fluorescence molecular tomography

    SciTech Connect

    Zhang, Guanglei; Pu, Huangsheng; Liu, Fei; Bai, Jing; He, Wei; Luo, Jianwen

    2015-02-23

    Images of pharmacokinetic parameters (also known as parametric images) in dynamic fluorescence molecular tomography (FMT) can provide three-dimensional metabolic information for biological studies and drug development. However, the ill-posed nature of FMT and the high temporal variation of fluorophore concentration together make it difficult to obtain accurate parametric images in small animals in vivo. In this letter, we present a method to directly reconstruct the parametric images from the boundary measurements based on hybrid FMT/X-ray computed tomography (XCT) system. This method can not only utilize structural priors obtained from the XCT system to mitigate the ill-posedness of FMT but also make full use of the temporal correlations of boundary measurements to model the high temporal variation of fluorophore concentration. The results of numerical simulation and mouse experiment demonstrate that the proposed method leads to significant improvements in the reconstruction quality of parametric images.

  9. Feshbach enhanced s-wave scattering of fermions: direct observation with optimized absorption imaging

    NASA Astrophysics Data System (ADS)

    Genkina, Dina; Aycock, Lauren; Stuhl, Benjamin; Lu, Hsin-I.; Williams, Ross; Spielman, Ian

    2016-05-01

    We directly measured the normalized s-wave scattering cross-section of ultracold 40 K atoms across a magnetic-field Feshbach resonance by colliding pairs of degenerate Fermi gases (DFGs) and imaging the scattered atoms. We extracted the scattered fraction for a range of bias magnetic fields, and measured the resonance location to be B 0 = 20.206(15) mT with width Δ = 1.0(5) mT. To optimize the signal-to-noise ratio (SNR) of atom number in scattering images, we developed techniques to interpret absorption images in a regime where recoil induced detuning corrections are significant. These imaging techniques are generally applicable to experiments with lighter alkalis that would benefit from maximizing SNR on atom number counting at the expense of spatial imaging resolution.

  10. Binocular retinal image differences influence eye-position signals for perceived visual direction.

    PubMed

    Sridhar, Deepika; Bedell, Harold E

    2012-06-01

    Correctly perceiving the direction of a visible object with respect to one's self (egocentric visual direction) requires that information about the location of the image on the retina (oculocentric visual direction) be combined with signals about the position of the eyes in the head. The Wells-Hering laws that govern the perception of visual direction and modern restatements of these laws assume implicitly that retinal and eye-position information are independent of one another. By measuring observers' manual pointing responses to targets in different horizontal locations, we show that retinal and eye-position information are not treated independently in the brain. In particular, decreasing the relative visibility of one eye's retinal image reduces the strength of the eye-position signal associated with that eye. The results can be accounted for by interactions between eye-specific retinal and eye-position signals at a common neural location. PMID:22560955

  11. A molecular image-directed, 3D ultrasound-guided biopsy system for the prostate

    NASA Astrophysics Data System (ADS)

    Fei, Baowei; Schuster, David M.; Master, Viraj; Akbari, Hamed; Fenster, Aaron; Nieh, Peter

    2012-02-01

    Systematic transrectal ultrasound (TRUS)-guided biopsy is the standard method for a definitive diagnosis of prostate cancer. However, this biopsy approach uses two-dimensional (2D) ultrasound images to guide biopsy and can miss up to 30% of prostate cancers. We are developing a molecular image-directed, three-dimensional (3D) ultrasound imageguided biopsy system for improved detection of prostate cancer. The system consists of a 3D mechanical localization system and software workstation for image segmentation, registration, and biopsy planning. In order to plan biopsy in a 3D prostate, we developed an automatic segmentation method based wavelet transform. In order to incorporate PET/CT images into ultrasound-guided biopsy, we developed image registration methods to fuse TRUS and PET/CT images. The segmentation method was tested in ten patients with a DICE overlap ratio of 92.4% +/- 1.1 %. The registration method has been tested in phantoms. The biopsy system was tested in prostate phantoms and 3D ultrasound images were acquired from two human patients. We are integrating the system for PET/CT directed, 3D ultrasound-guided, targeted biopsy in human patients.

  12. Susceptibility-Weighted Imaging of Glioma: Update on Current Imaging Status and Future Directions.

    PubMed

    Hsu, Charlie Chia-Tsong; Watkins, Trevor William; Kwan, Gigi Nga Chi; Haacke, E Mark

    2016-07-01

    Susceptibility-weighted imaging (SWI) provides invaluable insight into glioma pathophysiology and internal tumoral architecture. The physical contribution of intratumoral susceptibility signal (ITSS) may correspond to intralesional hemorrhage, calcification, or tumoral neovascularity. In this review, we present emerging evidence of ITSS for assessment of intratumoral calcification, grading of glioma, and factors influencing the pattern of ITSS in glioblastoma. SWI phase imaging assists in identification of intratumoral calcification that aids in narrowing the differential diagnosis. Development of intratumoral calcification posttreatment of glioma serves as an imaging marker of positive therapy response. Grading of tumors with ITSS using information attributed to microhemorrhage and neovascularity in SWI correlates with MR perfusion parameters and histologic grading of glioma and enriches preoperative prognosis. Quantitative susceptibility mapping may provide a means to discriminate subtle calcifications and hemorrhage in tumor imaging. Recent data suggest ITSS patterns in glioblastoma vary depending on tumoral volume and sublocation and correlate with degree of intratumoral necrosis and neovascularity. Increasingly, there is a recognized role of obtaining contrast-enhanced SWI (CE-SWI) for assessment of tumoral margin in high-grade glioma. Significant higher concentration of gadolinium accumulates at the border of the tumoral invasion zone as seen on the SWI sequence; this results from contrast-induced phase shift that clearly delineates the tumor margin. Lastly, absence of ITSS may aid in differentiation between high-grade glioma and primary CNS lymphoma, which typically shows absence of ITSS. We conclude that SWI and CE-SWI are indispensable tools for diagnosis, preoperative grading, posttherapy surveillance, and assessment of glioma. PMID:27227542

  13. Color-direction patch-sparsity-based image inpainting using multidirection features.

    PubMed

    Li, Zhidan; He, Hongjie; Tai, Heng-Ming; Yin, Zhongke; Chen, Fan

    2015-03-01

    This paper proposes a color-direction patch sparsity-based image in painting method to better maintain structure coherence, texture clarity, and neighborhood consistence of the in painted region of an image. The method uses super-wavelet transform to estimate the multi-direction features of a degraded image, and combines with color information to construct the weighted color-direction distance (WCDD) to measure the difference between two patches. Based on the WCDD, the color-direction structure sparsity is defined to obtain a more robust filling order and more suitable multiple candidate patches are searched. Then, the target patches are sparsely represented by the multiple candidate patches under neighborhood consistency constraints in both the color and the multi-direction spaces. Experimental results are presented to demonstrate the effectiveness of the proposed approach on tasks such as scratch removal, text removal, block removal, and object removal. The effects of super-wavelet transforms and direction features are also investigated. PMID:25532180

  14. Direct neural current imaging in an intact cerebellum with magnetic resonance imaging.

    PubMed

    Sundaram, Padmavathi; Nummenmaa, Aapo; Wells, William; Orbach, Darren; Orringer, Daniel; Mulkern, Robert; Okada, Yoshio

    2016-05-15

    The ability to detect neuronal currents with high spatiotemporal resolution using magnetic resonance imaging (MRI) is important for studying human brain function in both health and disease. While significant progress has been made, we still lack evidence showing that it is possible to measure an MR signal time-locked to neuronal currents with a temporal waveform matching concurrently recorded local field potentials (LFPs). Also lacking is evidence that such MR data can be used to image current distribution in active tissue. Since these two results are lacking even in vitro, we obtained these data in an intact isolated whole cerebellum of turtle during slow neuronal activity mediated by metabotropic glutamate receptors using a gradient-echo EPI sequence (TR=100ms) at 4.7T. Our results show that it is possible (1) to reliably detect an MR phase shift time course matching that of the concurrently measured LFP evoked by stimulation of a cerebellar peduncle, (2) to detect the signal in single voxels of 0.1mm(3), (3) to determine the spatial phase map matching the magnetic field distribution predicted by the LFP map, (4) to estimate the distribution of neuronal current in the active tissue from a group-average phase map, and (5) to provide a quantitatively accurate theoretical account of the measured phase shifts. The peak values of the detected MR phase shifts were 0.27-0.37°, corresponding to local magnetic field changes of 0.67-0.93nT (for TE=26ms). Our work provides an empirical basis for future extensions to in vivo imaging of neuronal currents. PMID:26899788

  15. Early flame development image comparison of low calorific value syngas and CNG in DI SI gas engine

    NASA Astrophysics Data System (ADS)

    >Ftwi Yohaness Hagos, A. Rashid A.; Sulaiman, Shaharin A.

    2013-06-01

    The early flame development stage of syngas and CNG are analysed and compared from the flame images taken over 20° CA from the start of ignition. An imitated syngas with a composition of 19.2% H2, 29.6% CO, 5.3% CH4 and balance with nitrogen and carbon dioxide, which resembles the typical product of wood biomass gasification, was used in the study. A CCD camera triggered externally through the signals from the camshaft and crank angle sensors was used in capturing of the images. The engine was accessed through an endoscope access and a self-illumination inside the chamber. The results of the image analysis are further compared with the mass fraction burn curve of both syngas and CNG analysed from the pressure data. The analysis result of the flame image of syngas validates the double rapid burning stage of the mass fraction burn of syngas analysed from in-cylinder pressure data.

  16. High-content analysis of single cells directly assembled on CMOS sensor based on color imaging.

    PubMed

    Tanaka, Tsuyoshi; Saeki, Tatsuya; Sunaga, Yoshihiko; Matsunaga, Tadashi

    2010-12-15

    A complementary metal oxide semiconductor (CMOS) image sensor was applied to high-content analysis of single cells which were assembled closely or directly onto the CMOS sensor surface. The direct assembling of cell groups on CMOS sensor surface allows large-field (6.66 mm×5.32 mm in entire active area of CMOS sensor) imaging within a second. Trypan blue-stained and non-stained cells in the same field area on the CMOS sensor were successfully distinguished as white- and blue-colored images under white LED light irradiation. Furthermore, the chemiluminescent signals of each cell were successfully visualized as blue-colored images on CMOS sensor only when HeLa cells were placed directly on the micro-lens array of the CMOS sensor. Our proposed approach will be a promising technique for real-time and high-content analysis of single cells in a large-field area based on color imaging. PMID:20728336

  17. Signal-to-Noise Behavior for Matches to Gradient Direction Models of Corners in Images

    SciTech Connect

    Paglieroni, D W; Manay, S

    2007-02-09

    Gradient direction models for corners of prescribed acuteness, leg length, and leg thickness are constructed by generating fields of unit vectors emanating from leg pixels that point normal to the edges. A novel FFT-based algorithm that quickly matches models of corners at all possible positions and orientations in the image to fields of gradient directions for image pixels is described. The signal strength of a corner is discussed in terms of the number of pixels along the edges of a corner in an image, while noise is characterized by the coherence of gradient directions along those edges. The detection-false alarm rate behavior of our corner detector is evaluated empirically by manually constructing maps of corner locations in typical overhead images, and then generating different ROC curves for matches to models of corners with different leg lengths and thicknesses. We then demonstrate how corners found with our detector can be used to quickly and automatically find families of polygons of arbitrary position, size and orientation in overhead images.

  18. Body image disturbance in children and adolescents with eating disorders. Current evidence and future directions.

    PubMed

    Legenbauer, Tanja; Thiemann, Pia; Vocks, Silja

    2014-01-01

    Body image is multifaceted and incorporates perceptual, affective, and cognitive components as well as behavioral features. Only few studies have examined the character of body-image disturbance in children/adolescents with eating disorders. It is unknown whether body-image disturbances in children/adolescent with eating disturbances are comparable to those of adult patients with eating disorders. Body-image disturbance might differ quantitatively and qualitatively according to the cognitive developmental status and the age of the individual. This paper provides an overview of the current evidence for body-image disturbance in children/adolescents with eating disorders, and how they compare with those adults with eating disorders. Current evidence indicates that older adolescent patients show similar deficits as adult patients with eating disorders, in particular for the attitudinal body-image component. However, evidence for a perceptual body-image disturbance in adolescent patients, in particular anorexia nervosa, is not conclusive. Reliable statements for childhood can hardly be made because clinical studies are not available. Investigations of body-image disturbance in children have focused on the predictive value for eating disorders. Limitations of the current evidence are discussed, and future directions for research and therapy are indicated. PMID:24365963

  19. Comparison of the diagnostic accuracy of direct digital radiography system, filtered images, and subtraction radiography

    PubMed Central

    Takeshita, Wilton Mitsunari; Vessoni Iwaki, Lilian Cristina; Da Silva, Mariliani Chicarelli; Filho, Liogi Iwaki; Queiroz, Alfredo De Franco; Geron, Lucas Bachegas Gomes

    2013-01-01

    Background: To compare the diagnostic accuracy of three different imaging systems: Direct digital radiography system (DDR-CMOS), four types of filtered images, and a priori and a posteriori registration of digital subtraction radiography (DSR) in the diagnosis of proximal defects. Materials and Methods: The teeth were arranged in pairs in 10 blocks of vinyl polysiloxane, and proximal defects were performed with drills of 0.25, 0.5, and 1 mm diameter. Kodak RVG 6100 sensor was used to capture the images. A posteriori DSR registrations were done with Regeemy 0.2.43 and subtraction with Image Tool 3.0. Filtered images were obtained with Kodak Dental Imaging 6.1 software. Images (n = 360) were evaluated by three raters, all experts in dental radiology. Results: Sensitivity and specificity of the area under the receiver operator characteristic (ROC) curve (Az) were higher for DSR images with all three drills (Az = 0.896, 0.979, and 1.000 for drills 0.25, 0.5, and 1 mm, respectively). The highest values were found for 1-mm drills and the lowest for 0.25-mm drills, with negative filter having the lowest values of all (Az = 0.631). Conclusion: The best method of diagnosis was by using a DSR. The negative filter obtained the worst results. Larger drills showed the highest sensitivity and specificity values of the area under the ROC curve. PMID:24124300

  20. Multidirectional edge-directed interpolation with region division for natural images

    NASA Astrophysics Data System (ADS)

    Yun, Yujin; Bae, Jonghyun; Kim, Jaeseok

    2012-04-01

    A multidirectional edge-directed interpolation algorithm that features a region division method is proposed. In the proposed method, an interpolation pixel is newly modeled as a weighted sum of 12 neighboring pixels representing 12 different directions. Each weight is estimated by Wiener filter theory using geometric duality. The proposed method for dividing the interpolation region reduces the heavy computational complexity of the proposed model. Analyzing edge continuities, the model divides an image into three regions, and only strong edge regions are interpolated. Simulation results show that several directional edges are restored clearly in a subjective test, with fair performance in an objective test.

  1. Direct imaging discovery of a Jovian exoplanet within a triple-star system.

    PubMed

    Wagner, Kevin; Apai, Dániel; Kasper, Markus; Kratter, Kaitlin; McClure, Melissa; Robberto, Massimo; Beuzit, Jean-Luc

    2016-08-12

    Direct imaging allows for the detection and characterization of exoplanets via their thermal emission. We report the discovery via imaging of a young Jovian planet in a triple-star system and characterize its atmospheric properties through near-infrared spectroscopy. The semimajor axis of the planet is closer relative to that of its hierarchical triple-star system than for any known exoplanet within a stellar binary or triple, making HD 131399 dynamically unlike any other known system. The location of HD 131399Ab on a wide orbit in a triple system demonstrates that massive planets may be found on long and possibly unstable orbits in multistar systems. HD 131399Ab is one of the lowest mass (4 ± 1 Jupiter masses) and coldest (850 ± 50 kelvin) exoplanets to have been directly imaged. PMID:27386921

  2. Direct imaging discovery of a Jovian exoplanet within a triple-star system

    NASA Astrophysics Data System (ADS)

    Wagner, Kevin; Apai, Dániel; Kasper, Markus; Kratter, Kaitlin; McClure, Melissa; Robberto, Massimo; Beuzit, Jean-Luc

    2016-08-01

    Direct imaging allows for the detection and characterization of exoplanets via their thermal emission. We report the discovery via imaging of a young Jovian planet in a triple-star system and characterize its atmospheric properties through near-infrared spectroscopy. The semimajor axis of the planet is closer relative to that of its hierarchical triple-star system than for any known exoplanet within a stellar binary or triple, making HD 131399 dynamically unlike any other known system. The location of HD 131399Ab on a wide orbit in a triple system demonstrates that massive planets may be found on long and possibly unstable orbits in multistar systems. HD 131399Ab is one of the lowest mass (4 ± 1 Jupiter masses) and coldest (850 ± 50 kelvin) exoplanets to have been directly imaged.

  3. Direct UV/Optical Imaging of Stellar Surfaces: The Stellar Imager (SI) Vision Mission

    NASA Technical Reports Server (NTRS)

    Carpenter, Kenneth G.; Lyon, Richard G.; Schrijver, Carolus; Karovska, Margarita; Mozurkewich, David

    2007-01-01

    The Stellar Imager (SI) is a UV/optical, space-based interferometer designed to enable 0.1 milli-arcsecond (mas) spectral imaging of stellar surfaces and, via asteroseismology, stellar interiors and of the Universe in general. SI's science focuses on the role of magnetism in the Universe, particularly on magnetic activity on the surfaces of stars like the Sun. SI's prime goal is to enable long-term forecasting of solar activity and the space weather that it drives, in support of the Living with a Star program in the Exploration Era. SI will also revolutionize our understanding of the formation of planetary systems, of the habitability and climatology of distant planets, and of many magneto-hydrodynamically controlled processes in thc Universe. SI is a "Flagship and Landmark Discovery Mission" in the 2005 Sun Solar System Connection (SSSC) Roadmap and a candidate for a "Pathways to Life Observatory" in the Exploration of the Universe Division (EUD) Roadmap. We discuss herein the science goals of the SI Mission, a mission architecture that could meet those goals, and the technologies needed to enable this mission. Additional information on SI can be found at: http://hires.gsfc.nasa.gov/si/.

  4. Astrometry of Directly Imaged Exoplanets after PSF Subtraction using MCMC Forward Modeling

    NASA Astrophysics Data System (ADS)

    Wang, Jason; Graham, James R.; Pueyo, Laurent; Ruffio, Jean-Baptise; GPIES Collaboration

    2016-01-01

    Direct imaging allows for the characterization of the orbits of exoplanets. However, to remove the glare of the host star, we must use observing strategies (e.g., angular differential imaging and spectral differential imaging) and data reduction techniques (e.g., Karhunen-Loève Image Projection; KLIP) that distort the apparent position of an exoplanet. Using recent methods to forward model the point spread function of a planet after using KLIP to subtract out the stellar light (Pueyo 2015), we are able to account for these astrometric biases. With the forward models, we can use a Markov chain Monte Carlo (MCMC) algorithm to derive the posterior distribution on the position of an exoplanet. To test our methodology, we apply our technique to Gemini Planet Imager integral field spectroscopy (IFS) data of the newly discovered exoplanet around 51 Eri and the extensively studied exoplanet beta Pictoris b. In general, this technique is applicable to any broadband direct imaging data and IFS data where the spectrum is assumed to be known.

  5. Direct reconstruction of cardiac PET kinetic parametric images using a preconditioned conjugate gradient approach

    PubMed Central

    Rakvongthai, Yothin; Ouyang, Jinsong; Guerin, Bastien; Li, Quanzheng; Alpert, Nathaniel M.; El Fakhri, Georges

    2013-01-01

    Purpose: Our research goal is to develop an algorithm to reconstruct cardiac positron emission tomography (PET) kinetic parametric images directly from sinograms and compare its performance with the conventional indirect approach. Methods: Time activity curves of a NCAT phantom were computed according to a one-tissue compartmental kinetic model with realistic kinetic parameters. The sinograms at each time frame were simulated using the activity distribution for the time frame. The authors reconstructed the parametric images directly from the sinograms by optimizing a cost function, which included the Poisson log-likelihood and a spatial regularization terms, using the preconditioned conjugate gradient (PCG) algorithm with the proposed preconditioner. The proposed preconditioner is a diagonal matrix whose diagonal entries are the ratio of the parameter and the sensitivity of the radioactivity associated with parameter. The authors compared the reconstructed parametric images using the direct approach with those reconstructed using the conventional indirect approach. Results: At the same bias, the direct approach yielded significant relative reduction in standard deviation by 12%–29% and 32%–70% for 50 × 106 and 10 × 106 detected coincidences counts, respectively. Also, the PCG method effectively reached a constant value after only 10 iterations (with numerical convergence achieved after 40–50 iterations), while more than 500 iterations were needed for CG. Conclusions: The authors have developed a novel approach based on the PCG algorithm to directly reconstruct cardiac PET parametric images from sinograms, and yield better estimation of kinetic parameters than the conventional indirect approach, i.e., curve fitting of reconstructed images. The PCG method increases the convergence rate of reconstruction significantly as compared to the conventional CG method. PMID:24089922

  6. Learning partially directed functional networks from meta-analysis imaging data

    PubMed Central

    Neumann, Jane; Fox, Peter T.; Turner, Robert; Lohmann, Gabriele

    2009-01-01

    We propose a new exploratory method for the discovery of partially directed functional networks from fMRI meta-analysis data. The method performs structure learning of Bayesian networks in search of directed probabilistic dependencies between brain regions. Learning is based on the co-activation of brain regions observed across several independent imaging experiments. In a series of simulations, we first demonstrate the reliability of the method. We then present the application of our approach in an extensive meta-analysis including several thousand activation coordinates from more than 500 imaging studies. Results show that our method is able to automatically infer Bayesian networks that capture both directed and undirected probabilistic dependencies between a number of brain regions, including regions that are frequently observed in motor-related and cognitive control tasks. PMID:19815079

  7. Direct estimation of nonrigid registrations with image-based self-occlusion reasoning.

    PubMed

    Gay-Bellile, Vincent; Bartoli, Adrien; Sayd, Patrick

    2010-01-01

    The registration problem for images of a deforming surface has been well studied. External occlusions are usually well handled. In 2D image-based registration, self-occlusions are more challenging. Consequently, the surface is usually assumed to be only slightly self-occluding. This paper is about image-based nonrigid registration with self-occlusion reasoning. A specific framework explicitly modeling self-occlusions is proposed. It is combined with an intensity-based, "direct" data term for registration. Self-occlusions are detected as shrinkage areas in the 2D warp. Experimental results on several challenging data sets show that our approach successfully registers images with self-occlusions while effectively detecting the self-occluded regions. PMID:19926901

  8. Discretized aperture mapping with a micro-lenses array for interferometric direct imaging

    NASA Astrophysics Data System (ADS)

    Patru, Fabien; Antichi, Jacopo; Mawet, Dimitri; Jolissaint, Laurent; Carbillet, Marcel; Milli, Julien; Girard, Julien; Rabou, Patrick; Giro, Enrico; Mourard, Denis

    2014-08-01

    Discretized Aperture Mapping (DAM) appears as an original filtering technique easy to play with existing adaptive optics (AO) systems. In its essential DAM operates as an optical passive filter removing part of the phase residuals in the wavefront without introducing any difficult-to-align component in the Fourier conjugate of the entrance pupil plane. DAM reveals as a new interferometric technique combined with spatial filtering allowing direct imaging over a narrow field of view (FOV). In fact, the entrance pupil of a single telescope is divided into many sub-pupils so that the residual phase in each sub-pupil is filtered up to the DAM cut-off frequency. DAM enables to smooth the small scale wavefront defects which correspond to high spatial frequencies in the pupil plane and to low angular frequencies in the image plane. Close to the AO Nyquist frequency, such pupil plane spatial frequencies are not well measured by the wavefront sensor (WFS) due to aliasing. Once bigger than the AO Nyquist frequency, they are no more measured by the WFS due to the fitting limit responsible for the narrow AO FOV. The corresponding image plane angular frequencies are not transmitted by DAM and are useless to image small FOVs, as stated by interferometry. That is why AO and DAM are complementary assuming that the DAM cut-off frequency is equal to the AO Nyquist frequency. Here we describe the imaging capabilities when DAM is placed downstream an AO system, over a convenient pupil which precedes the scientific detector. We show firstly that the imaging properties are preserved on a narrow FOV allowing direct imaging throughout interferometry. Then we show how the residual pupil plane spatial frequencies bigger than the AO Nyquist one are filtered out, as well as the residual halo in the image is dimmed.

  9. A pnCCD-based, fast direct single electron imaging camera for TEM and STEM

    NASA Astrophysics Data System (ADS)

    Ryll, H.; Simson, M.; Hartmann, R.; Holl, P.; Huth, M.; Ihle, S.; Kondo, Y.; Kotula, P.; Liebel, A.; Müller-Caspary, K.; Rosenauer, A.; Sagawa, R.; Schmidt, J.; Soltau, H.; Strüder, L.

    2016-04-01

    We report on a new camera that is based on a pnCCD sensor for applications in scanning transmission electron microscopy. Emerging new microscopy techniques demand improved detectors with regards to readout rate, sensitivity and radiation hardness, especially in scanning mode. The pnCCD is a 2D imaging sensor that meets these requirements. Its intrinsic radiation hardness permits direct detection of electrons. The pnCCD is read out at a rate of 1,150 frames per second with an image area of 264 x 264 pixel. In binning or windowing modes, the readout rate is increased almost linearly, for example to 4000 frames per second at 4× binning (264 x 66 pixel). Single electrons with energies from 300 keV down to 5 keV can be distinguished due to the high sensitivity of the detector. Three applications in scanning transmission electron microscopy are highlighted to demonstrate that the pnCCD satisfies experimental requirements, especially fast recording of 2D images. In the first application, 65536 2D diffraction patterns were recorded in 70 s. STEM images corresponding to intensities of various diffraction peaks were reconstructed. For the second application, the microscope was operated in a Lorentz-like mode. Magnetic domains were imaged in an area of 256 x 256 sample points in less than 37 seconds for a total of 65536 images each with 264 x 132 pixels. Due to information provided by the two-dimensional images, not only the amplitude but also the direction of the magnetic field could be determined. In the third application, millisecond images of a semiconductor nanostructure were recorded to determine the lattice strain in the sample. A speed-up in measurement time by a factor of 200 could be achieved compared to a previously used camera system.

  10. Testing zinc chloride as a new catalyst for direct synthesis of cellulose di- and tri-acetate in a solvent free system under microwave irradiation.

    PubMed

    El Nemr, Ahmed; Ragab, Safaa; El Sikaily, Amany

    2016-10-20

    This research demonstrates the effect of ZnCl2 as a catalyst on the esterification of commercial cotton cellulose using acetic anhydride in order to obtain di- and tri-cellulose acetates under microwave irradiation. It was discovered that microwave irradiation significantly increased the yield and reduced the reaction time. It was found that the maximum yield for cellulose triacetates was 95.83% under the reaction conditions that were as follows: 3min reaction time, 200mg of ZnCl2 catalyst and 20ml of Ac2O for 5g cellulose. However, the cellulose acetate obtained in this manner had the highest DS (2.87). The cellulose di-acetate was produced with the maximum yield of 89.97% and with the highest DS (2.69) using 25ml Ac2O, 200mg of ZnCl2 for 5g cellulose and in 3min reaction time. The effect of some factors such as the amount of used catalyst, the quantity of acetic acid anhydride and the reaction time of the esterification process have been investigated. The production of di- and tri-cellulose acetate and the degree of substitution were confirmed using Fourier-transform infrared (FTIR) and nuclear magnetic resonance (NMR). The thermal stability was investigated using thermo gravimetric analysis (TGA), differential thermal analysis (DTA) and differential scanning calorimetry (DSC). The molecular weight and the degree of polymerization were obtained using Gel Permeation Chromatography (GPC). The analysis confirmed the successful synthesis of di- and tri-cellulose acetate without degradation during the reaction; these results were found to be in contrast to some recent studies. The present study reveals that ZnCl2 is a new catalyst; it is effective as well as inexpensive and is a low toxicity catalyst for usage in cellulose esterification. PMID:27474655

  11. Direct-conversion flat-panel imager with avalanche gain: feasibility investigation for HARP-AMFPI.

    PubMed

    Wronski, M M; Rowlands, J A

    2008-12-01

    The authors are investigating the concept of a direct-conversion flat-panel imager with avalanche gain for low-dose x-ray imaging. It consists of an amorphous selenium (a-Se) photoconductor partitioned into a thick drift region for x-ray-to-charge conversion and a relatively thin region called high-gain avalanche rushing photoconductor (HARP) in which the charge undergoes avalanche multiplication. An active matrix of thin film transistors is used to read out the electronic image. The authors call the proposed imager HARP active matrix flat panel imager (HARP-AMFPI). The key advantages of HARP-AMFPI are its high spatial resolution, owing to the direct-conversion a-Se layer, and its programmable avalanche gain, which can be enabled during low dose fluoroscopy to overcome electronic noise and disabled during high dose radiography to prevent saturation of the detector elements. This article investigates key design considerations for HARP-AMFPI. The effects of electronic noise on the imaging performance of HARP-AMFPI were modeled theoretically and system parameters were optimized for radiography and fluoroscopy. The following imager properties were determined as a function of avalanche gain: (1) the spatial frequency dependent detective quantum efficiency; (2) fill factor; (3) dynamic range and linearity; and (4) gain nonuniformities resulting from electric field strength nonuniformities. The authors results showed that avalanche gains of 5 and 20 enable x-ray quantum noise limited performance throughout the entire exposure range in radiography and fluoroscopy, respectively. It was shown that HARP-AMFPI can provide the required gain while maintaining a 100% effective fill factor and a piecewise dynamic range over five orders of magnitude (10(-7)-10(-2) R/frame). The authors have also shown that imaging performance is not significantly affected by the following: electric field strength nonuniformities, avalanche noise for x-ray energies above 1 keV and direct interaction

  12. Direct-conversion flat-panel imager with avalanche gain: Feasibility investigation for HARP-AMFPI

    SciTech Connect

    Wronski, M. M.; Rowlands, J. A.

    2008-12-15

    The authors are investigating the concept of a direct-conversion flat-panel imager with avalanche gain for low-dose x-ray imaging. It consists of an amorphous selenium (a-Se) photoconductor partitioned into a thick drift region for x-ray-to-charge conversion and a relatively thin region called high-gain avalanche rushing photoconductor (HARP) in which the charge undergoes avalanche multiplication. An active matrix of thin film transistors is used to read out the electronic image. The authors call the proposed imager HARP active matrix flat panel imager (HARP-AMFPI). The key advantages of HARP-AMFPI are its high spatial resolution, owing to the direct-conversion a-Se layer, and its programmable avalanche gain, which can be enabled during low dose fluoroscopy to overcome electronic noise and disabled during high dose radiography to prevent saturation of the detector elements. This article investigates key design considerations for HARP-AMFPI. The effects of electronic noise on the imaging performance of HARP-AMFPI were modeled theoretically and system parameters were optimized for radiography and fluoroscopy. The following imager properties were determined as a function of avalanche gain: (1) the spatial frequency dependent detective quantum efficiency; (2) fill factor; (3) dynamic range and linearity; and (4) gain nonuniformities resulting from electric field strength nonuniformities. The authors results showed that avalanche gains of 5 and 20 enable x-ray quantum noise limited performance throughout the entire exposure range in radiography and fluoroscopy, respectively. It was shown that HARP-AMFPI can provide the required gain while maintaining a 100% effective fill factor and a piecewise dynamic range over five orders of magnitude (10{sup -7}-10{sup -2} R/frame). The authors have also shown that imaging performance is not significantly affected by the following: electric field strength nonuniformities, avalanche noise for x-ray energies above 1 keV and direct

  13. Direct-conversion flat-panel imager with avalanche gain: Feasibility investigation for HARP-AMFPI

    PubMed Central

    Wronski, M. M.; Rowlands, J. A.

    2008-01-01

    The authors are investigating the concept of a direct-conversion flat-panel imager with avalanche gain for low-dose x-ray imaging. It consists of an amorphous selenium (a-Se) photoconductor partitioned into a thick drift region for x-ray-to-charge conversion and a relatively thin region called high-gain avalanche rushing photoconductor (HARP) in which the charge undergoes avalanche multiplication. An active matrix of thin film transistors is used to read out the electronic image. The authors call the proposed imager HARP active matrix flat panel imager (HARP-AMFPI). The key advantages of HARP-AMFPI are its high spatial resolution, owing to the direct-conversion a-Se layer, and its programmable avalanche gain, which can be enabled during low dose fluoroscopy to overcome electronic noise and disabled during high dose radiography to prevent saturation of the detector elements. This article investigates key design considerations for HARP-AMFPI. The effects of electronic noise on the imaging performance of HARP-AMFPI were modeled theoretically and system parameters were optimized for radiography and fluoroscopy. The following imager properties were determined as a function of avalanche gain: (1) the spatial frequency dependent detective quantum efficiency; (2) fill factor; (3) dynamic range and linearity; and (4) gain nonuniformities resulting from electric field strength nonuniformities. The authors results showed that avalanche gains of 5 and 20 enable x-ray quantum noise limited performance throughout the entire exposure range in radiography and fluoroscopy, respectively. It was shown that HARP-AMFPI can provide the required gain while maintaining a 100% effective fill factor and a piecewise dynamic range over five orders of magnitude (10−7–10−2 R∕frame). The authors have also shown that imaging performance is not significantly affected by the following: electric field strength nonuniformities, avalanche noise for x-ray energies above 1 keV and direct

  14. Investigating Non-Equilibrium Fluctuations of Nanocolloids in a Magnetic Field Using Direct Imaging Methods

    NASA Astrophysics Data System (ADS)

    Rice, Ashley; Oprisan, Ana; Oprisan, Sorinel; Rice-Oprisan College of Charleston Team

    Nanoparticles of iron oxide have a high surface area and can be controlled by an external magnetic field. Since they have a fast response to the applied magnetic field, these systems have been used for numerous in vivo applications, such as MRI contrast enhancement, tissue repair, immunoassay, detoxification of biological fluids, hyperthermia, drug delivery, and cell separation. We performed three direct imaging experiments in order to investigate the concentration-driven fluctuations using magnetic nanoparticles in the absence and in the presence of magnetic field. Our direct imaging experimental setup involved a glass cell filled with magnetic nanocolloidal suspension and water with the concentration gradient oriented against the gravitational field and a superluminescent diode (SLD) as the light source. Nonequilibrium concentration-driven fluctuations were recorded using a direct imaging technique. We used a dynamic structure factor algorithm for image processing in order to compute the structure factor and to find the power law exponents. We saw evidence of large concentration fluctuations and permanent magnetism. Further research will use the correlation time to approximate the diffusion coefficient for the free diffusion experiment. Funded by College of Charleston Department of Undergraduate Research and Creative Activities SURF grant.

  15. Space telescope design to directly image the habitable zone of Alpha Centauri

    NASA Astrophysics Data System (ADS)

    Bendek, Eduardo A.; Belikov, Ruslan; Lozi, Julien; Thomas, Sandrine; Males, Jared; Weston, Sasha; McElwain, Michael

    2015-09-01

    The scientific interest in directly imaging and identifying Earth-like planets within the Habitable Zone (HZ) around nearby stars is driving the design of specialized direct imaging missions such as ACESAT, EXO-C, EXO-S and AFTA-C. The inner edge of Alpha Cen A and B Habitable Zone is found at exceptionally large angular separations of 0.7" and 0.4" respectively. This enables direct imaging of the system with a 0.3m class telescope. Contrast ratios on the order of 1010 are needed to image Earth-brightness planets. Low-resolution (5-band) spectra of all planets may allow establishing the presence and amount of an atmosphere. This star system configuration is optimal for a specialized small, and stable space telescope that can achieve high-contrast but has limited resolution. This paper describes an innovative instrument design and a mission concept based on a full Silicon Carbide off-axis telescope, which has a Phase Induced Amplitude Apodization coronagraph embedded in the telescope. This architecture maximizes stability and throughput. A Multi-Star Wave Front algorithm is implemented to drive a deformable mirror controlling simultaneously diffracted light from the on-axis and binary companion star. The instrument has a Focal Plane Occulter to reject starlight into a highprecision pointing control camera. Finally we utilize a Orbital Differential Imaging (ODI) post-processing method that takes advantage of a highly stable environment (Earth-trailing orbit) and a continuous sequence of images spanning 2 years, to reduce the final noise floor in post processing to ~2e-11 levels, enabling high confidence and at least 90% completeness detections of Earth-like planets.

  16. Translation invariant directional framelet transform combined with Gabor filters for image denoising.

    PubMed

    Shi, Yan; Yang, Xiaoyuan; Guo, Yuhua

    2014-01-01

    This paper is devoted to the study of a directional lifting transform for wavelet frames. A nonsubsampled lifting structure is developed to maintain the translation invariance as it is an important property in image denoising. Then, the directionality of the lifting-based tight frame is explicitly discussed, followed by a specific translation invariant directional framelet transform (TIDFT). The TIDFT has two framelets ψ1, ψ2 with vanishing moments of order two and one respectively, which are able to detect singularities in a given direction set. It provides an efficient and sparse representation for images containing rich textures along with properties of fast implementation and perfect reconstruction. In addition, an adaptive block-wise orientation estimation method based on Gabor filters is presented instead of the conventional minimization of residuals. Furthermore, the TIDFT is utilized to exploit the capability of image denoising, incorporating the MAP estimator for multivariate exponential distribution. Consequently, the TIDFT is able to eliminate the noise effectively while preserving the textures simultaneously. Experimental results show that the TIDFT outperforms some other frame-based denoising methods, such as contourlet and shearlet, and is competitive to the state-of-the-art denoising approaches. PMID:24215934

  17. THE STRUCTURE OF A SELF-GRAVITATING PROTOPLANETARY DISK AND ITS IMPLICATIONS FOR DIRECT IMAGING OBSERVATIONS

    SciTech Connect

    Muto, Takayuki

    2011-09-20

    We consider the effects of self-gravity on the hydrostatic balance in the vertical direction of a gaseous disk and discuss the possible signature of the self-gravity that may be captured by direct imaging observations of protoplanetary disks in the future. In this paper, we consider a vertically isothermal disk in order to isolate the effects of self-gravity. The specific disk model we consider in this paper is the one with a radial surface density gap, at which the Toomre's Q-parameter of the disk varies rapidly in the radial direction. We calculate the vertical structure of the disk including the effects of self-gravity. We then calculate the scattered light and the dust thermal emission. We find that if the disk is massive enough and the effects of self-gravity come into play, a weak bump-like structure at the gap edge appears in the near-infrared (NIR) scattered light, while no such bump-like structure is seen in the submillimeter (sub-mm) dust continuum image. The appearance of the bump is caused by the variation of the height of the surface in the NIR wavelength. If such a bump-like feature is detected in future direct imaging observations, combined with sub-mm observations, it will give us useful information about the physical states of the disk.

  18. Resampling technique in the orthogonal direction for down-looking Synthetic Aperture Imaging Ladar

    NASA Astrophysics Data System (ADS)

    Li, Guangyuan; Sun, Jianfeng; Lu, Zhiyong; Zhang, Ning; Cai, Guangyu; Sun, Zhiwei; Liu, Liren

    2015-09-01

    The implementation of down-looking Synthetic Aperture Imaging Ladar(SAIL) uses quadratic phase history reconstruction in the travel direction and linear phase modulation reconstruction in the orthogonal direction. And the linear phase modulation in the orthogonal direction is generated by the shift of two cylindrical lenses in the two polarization-orthogonal beams. Therefore, the fast-moving of two cylindrical lenses is necessary for airborne down-looking SAIL to match the aircraft flight speed and to realize the compression of the orthogonal direction, but the quick start and the quick stop of the cylindrical lenses must greatly damage the motor and make the motion trail non-uniform. To reduce the damage and get relatively well trajectory, we make the motor move like a sinusoidal curve to make it more realistic movement, and through a resampling interpolation imaging algorithm, we can transform the nonlinear phase to linear phase, and get good reconstruction results of point target and area target in laboratory. The influences on imaging quality in different sampling positions when the motor make a sinusoidal motion and the necessity of the algorithm are analyzed. At last, we perform a comparison of the results of two cases in resolution.

  19. How to Directly Image a Habitable Planet Around Alpha Centauri with a 30cm Space Telescope.

    NASA Astrophysics Data System (ADS)

    Belikov, R.; Bendek, E.; Thomas, S.; Black, D.

    2014-12-01

    More than 1,700 exoplanets have been discovered to date, including a handful of potentially habitable ones. There is on average more than one planet per star, and estimates of occurrence rates for potentially habitable planets (eta_Earth) from the Kepler mission range between 5 and 50%. Several mission concepts have been studied to directly image planets around nearby stars. Direct imaging enables spectroscopic detection of biomarkers such as atmospheric oxygen and methane, which would be highly suggestive of extraterrestrial life. It is commonly thought that directly imaging a potentially habitable exoplanet requires telescopes with apertures of at least 1m, costing at least $1B, and launching no earlier than the 2020s. A notable exception to this is Alpha Centauri. The system contains two Sun-like stars with a wide separation that allows dynamically stable habitable zones around either star. Habitable zones span about 0.5-1" in stellocentric angle, 3x wider than around any other FGKM star. A 30cm visible light space telescope is sufficient to resolve the habitable zone and detect a potentially habitable planet in minutes with ideal components, or days with realistic ones. We are developing a mission concept called ACEND (Alpha Centauri Direct Imager) consisting of a 30cm primary, a Phase-Induced Amplitude Apodization coronagraph, and a wavefront control system. It is designed to suppress the light leak from both stars and directly image their planetary systems in 3 color channels, including the capability to detect potentially habitable planets. Color imaging is sufficient to differentiate Venus-like, Earth-like, and Mars-like planets from each other and establish the presence of Earth-pressure atmosphere through Rayleigh scattering. Two factors make it possible to realize the requirements of ACEND (most notably 10^10 contrast) on a small budget and fast schedule: (a) ACEND will collect a long continuous sequence of images on Alpha Centauri A and B for 2 years

  20. Inorganic chemistry in nuclear imaging and radiotherapy: current and future directions

    PubMed Central

    Carroll, Valerie; Demoin, Dustin W.; Hoffman, Timothy J; Jurisson, Silvia S

    2013-01-01

    Summary Radiometals play an important role in diagnostic and therapeutic radiopharmaceuticals. This field of radiochemistry is multidisciplinary, involving radiometal production, separation of the radiometal from its target, chelate design for complexing the radiometal in a biologically stable environment, specific targeting of the radiometal to its in vivo site, and nuclear imaging and/or radiotherapy applications of the resultant radiopharmaceutical. The critical importance of inorganic chemistry in the design and application of radiometal-containing imaging and therapy agents is described from a historical perspective to future directions. PMID:25382874

  1. Detection and direct identification of liquid contaminants at standoff distances with an imaging polarimetric spectrometer

    NASA Astrophysics Data System (ADS)

    Tsiang, Eugene; Oberbeck, Adam; Akagi, Jason; Knobbe, Ed

    2015-06-01

    We demonstrate a remote sensing method, based on an imaging polarimetric spectrometer, to determine the complex refractive index of materials. The approach represents an adaptation of a technique used in semiconductor ellipsometry. Our experimental demonstration setup comprises a Sagnac-type LWIR spatial interferometer (8 - 12 micron) designed for hyperspectral imaging in emission and reflection. The method facilitates direct measurement of the complex refractive index and the thickness of a layer. Presented work focuses on SF96, a liquid surrogate for toxic chemicals, but the method is generally applicable to solids, including soils, and to any substrate with a general bidirectional reflectance distribution function.

  2. Infrared adaptive spectral imagers for direct detection of spectral signatures and hyperspectral imagery

    NASA Astrophysics Data System (ADS)

    Goldstein, Neil; Fox, Marsha; Adler-Golden, Steven; Gregor, Brian

    2013-03-01

    Field test results are presented for a prototype long-wave adaptive imager that provides both hyperspectral imagery and contrast imagery based on the direct application of hyperspectral detection algorithms in hardware. Programmable spatial light modulators are used to provide both spectral and spatial resolution using a single element detector. Programmable spectral and spatial detection filters can be used to superimpose any possible analog spectral detection filter on the image. In this work, we demonstrate three modes of operation, including hyperspectral imagery, and one and two-dimensional imagery using a generalized matched filter for detection of a specific target gas within the scene.

  3. Direct Geolocation of TerraSAR-X Spotlight Mode Image and Error Correction

    NASA Astrophysics Data System (ADS)

    Zhou, Xiao; Zeng, Qiming; Jiao, Jian; Zhang, Jingfa; Gong, Lixia

    2013-01-01

    The research dealt with direct geolocation of spaceborne high-resolution SAR image. The TerraSAR-X spotlight mode image was chosen as the study object. The mathematical model of SAR geolocation is Range-Doppler (RD) model. Its resolving algorithms had been studied and the ASF algorithm was chosen because of its high accuracy. The focus of this research laid on the error sources and their correction method which could affect the geolocation accuracy, such as the orbit errors, azimuth timing errors and range timing errors. At last, the accuracy of this method was verified by the experiment results.

  4. Direct imaging of periodic subwavelength patterns generated by optical phase masks

    SciTech Connect

    Tonyushkin, Alexei; Sleator, Tycho

    2006-11-15

    We have demonstrated direct imaging of interference fringes of total atomic density with periods {lambda}/4 and {lambda}/2 for optical wavelength {lambda} that have been produced in a de Broglie wave atom interferometer. The imaging was done by means of an 'optical mask' technique, which allowed us to observe subwavelength periodic patterns with a resolution of up to {lambda}/16. In addition, the dependence of the fringe pattern on the recoil phase and pulse area reveals quantum dynamics in the atomic center-of-mass motion. The behavior of the fringe patterns near the interference times distinguishes the effects of phase gratings from those of amplitude gratings.

  5. Calculating the propagation direction of coronal mass ejections by connecting in situ observations with heliospheric images

    NASA Astrophysics Data System (ADS)

    Rollett, Tanja; Möstl, Christian; Temmer, Manuela; Veronig, Astrid; Biernat, Helfried K.

    2010-05-01

    We determined the propagation direction of two coronal mass ejections by using data provided by the Heliospheric Imagers (HI) and the PLASTIC and IMPACT instruments onboard the two STEREO satellites. To facilitate the tracking of the CME's leading edge we made time-elongation plots (J-plots) for the investigated events and tracked the apparent leading edge therein several times in order to estimate the measurement error. For converting elongation to distance we compared several methods (Point-P, Fixed-Phi and their harmonic mean). To determine the direction of the CME's propagation in the ecliptic we connected the CME-track derived from HI J-plots with the measured in situ arrival time by modifying the propagation direction within the used model equations. The resulting directions and their errors are discussed with respect to the different assumptions used for each technique.

  6. Efficient completion for corrupted low-rank images via alternating direction method

    NASA Astrophysics Data System (ADS)

    Li, Wei; Zhao, Lei; Xu, Duanqing; Lu, Dongming

    2014-05-01

    We propose an efficient and easy-to-implement method to settle the inpainting problem for low-rank images following the recent studies about low-rank matrix completion. In general, our method has three steps: first, corresponding to the three channels of RGB color space, an incomplete image is split into three incomplete matrices; second, each matrix is restored by solving a convex problem derived from the nuclear norm relaxation; at last, the three recovered matrices are merged to produce the final output. During the process, in order to efficiently solve the nuclear norm minimization problem, we employ the alternating direction method. Except for the basic image inpainting problem, we also enable our method to handle cases where corrupted images not only have missing values but also have noisy entries. Our experiments show that our method outperforms the existing inpainting techniques both quantitatively and qualitatively. We also demonstrate that our method is capable of processing many other situations, including block-wise low-rank image completion, large-scale image restoration, and object removal.

  7. Direct design of two freeform optical surfaces for wide field of view line imaging applications

    NASA Astrophysics Data System (ADS)

    Nie, Yunfeng; Thienpont, Hugo; Duerr, Fabian

    2016-04-01

    In this paper, we propose a multi-fields direct design method aiming to calculate two freeform surfaces with an entrance pupil incorporated for wide field of view on-axis line imaging applications. Both infinite and finite conjugate objectives can be designed with this approach. Since a wide angle imaging system requires more than few discrete perfect imaging points, the multi-fields design approach is based on partial coupling of multiple fields, which guarantees a much more balanced imaging performance over the full field of view. The optical path lengths (OPLs) and image points of numerous off-axis fields are calculated during the procedure, thus very few initial parameters are needed. The procedure to calculate such a freeform lens is explained in detail. We have designed an exemplary monochromatic single lens to demonstrate the functionality of the design method. A rotationally symmetric counterpart following the same specifications is compared in terms of RMS spot radius to demonstrate the clear benefit that freeform lens brings to on-axis line imaging systems. In addition, a practical achromatic wide angle objective is designed by combining our multi-fields design method with classic optical design strategies, serving as a very good starting point for further optimization in a commercial optical design program. The results from the perspective of aberrations plots and MTF values show a very good and well balanced performance over the full field of view.

  8. Direct tissue oxygen monitoring by in vivo photoacoustic lifetime imaging (PALI)

    NASA Astrophysics Data System (ADS)

    Shao, Qi; Morgounova, Ekaterina; Ashkenazi, Shai

    2014-03-01

    Tissue oxygen plays a critical role in maintaining tissue viability and in various diseases, including response to therapy. Images of oxygen distribution provide the history of tissue hypoxia and evidence of oxygen availability in the circulatory system. Currently available methods of direct measuring or imaging tissue oxygen all have significant limitations. Previously, we have reported a non-invasive in vivo imaging modality based on photoacoustic lifetime. The technique maps the excited triplet state of oxygen-sensitive dye, thus reflects the spatial and temporal distribution of tissue oxygen. We have applied PALI on tumor hypoxia in small animals, and the hypoxic region imaged by PALI is consistent with the site of the tumor imaged by ultrasound. Here, we present two studies of applying PALI to monitor changes of tissue oxygen by modulations. The first study involves an acute ischemia model using a thin thread tied around the hind limb of a normal mouse to reduce the blood flow. PALI images were acquired before, during, and after the restriction. The drop of muscle pO2 and recovery from hypoxia due to reperfusion were observed by PALI tracking the same region. The second study modulates tissue oxygen by controlling the percentage of oxygen the mouse inhales. We demonstrate that PALI is able to reflect the change of oxygen level with respect to both hyperbaric and hypobaric conditions. We expect this technique to be very attractive for a range of clinical applications in which tissue oxygen mapping would improve therapy decision making and treatment planning.

  9. The dynamic effect of reading direction habit on spatial asymmetry of image perception.

    PubMed

    Afsari, Zaeinab; Ossandón, José P; König, Peter

    2016-09-01

    Exploration of images after stimulus onset is initially biased to the left. Here, we studied the causes of such an asymmetry and investigated effects of reading habits, text primes, and priming by systematically biased eye movements on this spatial bias in visual exploration. Bilinguals first read text primes with right-to-left (RTL) or left-to-right (LTR) reading directions and subsequently explored natural images. In Experiment 1, native RTL speakers showed a leftward free-viewing shift after reading LTR primes but a weaker rightward bias after reading RTL primes. This demonstrates that reading direction dynamically influences the spatial bias. However, native LTR speakers who learned an RTL language late in life showed a leftward bias after reading either LTR or RTL primes, which suggests the role of habit formation in the production of the spatial bias. In Experiment 2, LTR bilinguals showed a slightly enhanced leftward bias after reading LTR text primes in their second language. This might contribute to the differences of native RTL and LTR speakers observed in Experiment 1. In Experiment 3, LTR bilinguals read normal (LTR, habitual reading) and mirrored left-to-right (mLTR, nonhabitual reading) texts. We observed a strong leftward bias in both cases, indicating that the bias direction is influenced by habitual reading direction and is not secondary to the actual reading direction. This is confirmed in Experiment 4, in which LTR participants were asked to follow RTL and LTR moving dots in prior image presentation and showed no change in the normal spatial bias. In conclusion, the horizontal bias is a dynamic property and is modulated by habitual reading direction. PMID:27611064

  10. Direction operator-based switching filters for removing the impulse noise from the corrupted image

    NASA Astrophysics Data System (ADS)

    Wu, Chang Cheng; Qiu, Hong Tong; He, Guang Jin

    2011-12-01

    A novel switching-based filter is proposed in this work to remove the impulse noise from the corrupted image. First, samples in 5×5 filter window are fully considered to detect whether the center is corrupted by impulse noise or not. Then, the detected noise free samples in the 5×5 filter window, aligned in the main direction, are weighted more heavily than those that are not on the main direction when using the median operation to suppress the impulse noise. At last, simulation results demonstrated that this algorithm outperforms many other methods in terms of both quantitative and qualitative aspects.

  11. Direct Imaging of Dynamic Glassy Behavior in a Strained Manganite Film.

    PubMed

    Kundhikanjana, Worasom; Sheng, Zhigao; Yang, Yongliang; Lai, Keji; Ma, Eric Yue; Cui, Yong-Tao; Kelly, Michael A; Nakamura, Masao; Kawasaki, Masashi; Tokura, Yoshinori; Tang, Qiaochu; Zhang, Kun; Li, Xinxin; Shen, Zhi-Xun

    2015-12-31

    Complex many-body interaction in perovskite manganites gives rise to a strong competition between ferromagnetic metallic and charge-ordered phases with nanoscale electronic inhomogeneity and glassy behaviors. Investigating this glassy state requires high-resolution imaging techniques with sufficient sensitivity and stability. Here, we present the results of a near-field microwave microscope imaging on the strain-driven glassy state in a manganite film. The high contrast between the two electrically distinct phases allows direct visualization of the phase separation. The low-temperature microscopic configurations differ upon cooling with different thermal histories. At sufficiently high temperatures, we observe switching between the two phases in either direction. The dynamic switching, however, stops below the glass transition temperature. Compared with the magnetization data, the phase separation was microscopically frozen, while spin relaxation was found in a short period of time. PMID:26765006

  12. Direct imaging of complex nano- to microscale interfaces involving solid, liquid, and gas phases.

    PubMed

    Rykaczewski, Konrad; Landin, Trevan; Walker, Marlon L; Scott, John Henry J; Varanasi, Kripa K

    2012-10-23

    Surfaces with special wetting properties not only can efficiently repel or attract liquids such as water and oils but also can prevent formation of biofilms, ice, and clathrate hydrates. Predicting the wetting properties of these special surfaces requires detailed knowledge of the composition and geometry of the interfacial region between the droplet and the underlying substrate. In this work we introduce a 3D quantitative method for direct nanoscale visualization of such interfaces. Specifically, we demonstrate direct nano- to microscale imaging of complex fluidic interfaces using cryostabilization in combination with cryogenic focused ion beam milling and SEM imaging. We show that application of this method yields quantitative information about the interfacial geometry of water condensate on superhydrophilic, superhydrophobic, and lubricant-impregnated surfaces with previously unattainable nanoscale resolution. This type of information is crucial to a fundamental understanding as well as the design of surfaces with special wetting properties. PMID:23020195

  13. Direct imaging of topological edge states in cold-atom systems

    PubMed Central

    Goldman, Nathan; Dalibard, Jean; Dauphin, Alexandre; Gerbier, Fabrice; Lewenstein, Maciej; Zoller, Peter; Spielman, Ian B.

    2013-01-01

    Detecting topological order in cold-atom experiments is an ongoing challenge, the resolution of which offers novel perspectives on topological matter. In material systems, unambiguous signatures of topological order exist for topological insulators and quantum Hall devices. In quantum Hall systems, the quantized conductivity and the associated robust propagating edge modes—guaranteed by the existence of nontrivial topological invariants—have been observed through transport and spectroscopy measurements. Here, we show that optical-lattice-based experiments can be tailored to directly visualize the propagation of topological edge modes. Our method is rooted in the unique capability for initially shaping the atomic gas and imaging its time evolution after suddenly removing the shaping potentials. Our scheme, applicable to an assortment of atomic topological phases, provides a method for imaging the dynamics of topological edge modes, directly revealing their angular velocity and spin structure. PMID:23569266

  14. Direct imaging of topological edge states in cold-atom systems.

    PubMed

    Goldman, Nathan; Dalibard, Jean; Dauphin, Alexandre; Gerbier, Fabrice; Lewenstein, Maciej; Zoller, Peter; Spielman, Ian B

    2013-04-23

    Detecting topological order in cold-atom experiments is an ongoing challenge, the resolution of which offers novel perspectives on topological matter. In material systems, unambiguous signatures of topological order exist for topological insulators and quantum Hall devices. In quantum Hall systems, the quantized conductivity and the associated robust propagating edge modes--guaranteed by the existence of nontrivial topological invariants--have been observed through transport and spectroscopy measurements. Here, we show that optical-lattice-based experiments can be tailored to directly visualize the propagation of topological edge modes. Our method is rooted in the unique capability for initially shaping the atomic gas and imaging its time evolution after suddenly removing the shaping potentials. Our scheme, applicable to an assortment of atomic topological phases, provides a method for imaging the dynamics of topological edge modes, directly revealing their angular velocity and spin structure. PMID:23569266

  15. Resolving the Crab Nebula with Direct Hard X-Ray Imaging

    NASA Technical Reports Server (NTRS)

    Swartz, Douglas A.; Ramsey, Brian D.; Tennant, Allyn F.; Dietz, Kurtis L.; Apple, Jeff A.; Gaskin, Jessica A.; Weisskopf, Martin

    2008-01-01

    We report the first direct hard (25--60 keV) X-ray imaging observation of the Crab Nebula that resolves structure to approximately 0.25 pc. The observation was performed over a 1.4 hour period during a balloon flight from Ft. Sumner, NM, on 2007 May 27. The source was detected in the energy band above the atmospheric cutoff at approx.25 keV and below the mirror graze angle cutoff at approx.60 keV. The image shows elongation about 25 degrees E of N in the direction along the plane of the torus (and perpendicular to the jet axis) with a slight surface-brightness enhancement NE of the pulsar. The spectrum within a 1.7 arcminute radius region centered on the Crab pulsar can be fitted with a Gamma=2 power law absorbed by an atmospheric column consistent with the balloon altitude at the time of observation.

  16. Direct Imaging of Dynamic Glassy Behavior in a Strained Manganite Film

    NASA Astrophysics Data System (ADS)

    Kundhikanjana, Worasom; Sheng, Zhigao; Yang, Yongliang; Lai, Keji; Ma, Eric Yue; Cui, Yong-Tao; Kelly, Michael A.; Nakamura, Masao; Kawasaki, Masashi; Tokura, Yoshinori; Tang, Qiaochu; Zhang, Kun; Li, Xinxin; Shen, Zhi-Xun

    2015-12-01

    Complex many-body interaction in perovskite manganites gives rise to a strong competition between ferromagnetic metallic and charge-ordered phases with nanoscale electronic inhomogeneity and glassy behaviors. Investigating this glassy state requires high-resolution imaging techniques with sufficient sensitivity and stability. Here, we present the results of a near-field microwave microscope imaging on the strain-driven glassy state in a manganite film. The high contrast between the two electrically distinct phases allows direct visualization of the phase separation. The low-temperature microscopic configurations differ upon cooling with different thermal histories. At sufficiently high temperatures, we observe switching between the two phases in either direction. The dynamic switching, however, stops below the glass transition temperature. Compared with the magnetization data, the phase separation was microscopically frozen, while spin relaxation was found in a short period of time.

  17. A format standard for efficient interchange of high-contrast direct imaging science products

    NASA Astrophysics Data System (ADS)

    Choquet, Élodie; Vigan, Arthur; Soummer, Rémi; Chauvin, Gaël.; Pueyo, Laurent; Perrin, Marshall D.; Hines, Dean C.

    2014-07-01

    The present and next few years will see the arrival of several new coronagraphic instruments dedicated to the detection and characterization of planetary systems. These ground- and space-based instruments (Gemini/GPI, VLT/SPHERE, Subaru/ CHARIS, JWST NIRCam and MIRI coronagraphs among others), will provide a large number of new candidates, through multiple nearby-star surveys and will complete and extend those acquired with current generation instruments (Palomar P1640, VLT/NACO, Keck, HST). To optimize the use of the wealth of data, including non-detection results, the science products of these instruments will require to be shared among the community. In the long term such data exchange will significantly ease companion confirmations, planet characterization via different type of instruments (integral field spectrographs, polarimetric imagers, etc.), and Monte-Carlo population studies from detection and non-detection results. In this context, we initiated a collaborative effort between the teams developing the data reduction pipelines for SPHERE, GPI, and the JWST coronagraphs, and the ALICE (Archival Legacy Investigations of Circumstellar Environment) collaboration, which is currently reprocessing all the HST/NICMOS coronagraphic surveys. We are developing a standard format for the science products generated by high-contrast direct imaging instruments (reduced image, sensitivity limits, noise image, candidate list, etc.), that is directly usable for astrophysical investigations. In this paper, we present first results of this work and propose a preliminary format adopted for the science product. We call for discussions in the high-contrast direct imaging community to develop this effort, reach a consensus and finalize this standard. This action will be critical to enable data interchange and combination in a consistent way between several instruments and to stiffen the scientific production in the community.

  18. Direct Visualization of the Perforant Pathway in the Human Brain with Ex Vivo Diffusion Tensor Imaging

    PubMed Central

    Augustinack, Jean C.; Helmer, Karl; Huber, Kristen E.; Kakunoori, Sita; Zöllei, Lilla; Fischl, Bruce

    2010-01-01

    Ex vivo magnetic resonance imaging yields high resolution images that reveal detailed cerebral anatomy and explicit cytoarchitecture in the cerebral cortex, subcortical structures, and white matter in the human brain. Our data illustrate neuroanatomical correlates of limbic circuitry with high resolution images at high field. In this report, we have studied ex vivo medial temporal lobe samples in high resolution structural MRI and high resolution diffusion MRI. Structural and diffusion MRIs were registered to each other and to histological sections stained for myelin for validation of the perforant pathway. We demonstrate probability maps and fiber tracking from diffusion tensor data that allows the direct visualization of the perforant pathway. Although it is not possible to validate the DTI data with invasive measures, results described here provide an additional line of evidence of the perforant pathway trajectory in the human brain and that the perforant pathway may cross the hippocampal sulcus. PMID:20577631

  19. Application of an imaging plate system to the direct measurement of a fixed surface contamination.

    PubMed

    Hirota, Masahiro; Kimura, Keiji; Sato, Rumi; Koike, Yuya; Iimoto, Takeshi; Tanaka, Satoru

    2014-08-01

    An imaging plate (IP) system was used as an effective detector for direct measurement of radioactive surface contamination. The IP system displayed images designating the locations and extent of fixed surface contamination of uranyl acetate. The amount of radioactive waste produced during decontamination was reduced because the contaminated spots could be isolated; furthermore, creation of radioactive dust during removal of contamination was prevented because the contaminated spots could be removed without being pulverized. The images were used in efficiently and safely isolating the location of fixed surface contamination. The IP system surface contamination detection limit for uranyl acetate was 2.5 × 10 Bq cm, a value much lower than the surface contamination limit and the clearance level. PMID:24978288

  20. Direct imaging of topological edge states at a bilayer graphene domain wall.

    PubMed

    Yin, Long-Jing; Jiang, Hua; Qiao, Jia-Bin; He, Lin

    2016-01-01

    The AB-BA domain wall in gapped graphene bilayers is a rare naked structure hosting topological electronic states. Although it has been extensively studied in theory, a direct imaging of its topological edge states is still missing. Here we image the topological edge states at the graphene bilayer domain wall by using scanning tunnelling microscope. The simultaneously obtained atomic-resolution images of the domain wall provide us unprecedented opportunities to measure the spatially varying edge states within it. The one-dimensional conducting channels are observed to be mainly located around the two edges of the domain wall, which is reproduced quite well by our theoretical calculations. Our experiment further demonstrates that the one-dimensional topological states are quite robust even in the presence of high magnetic fields. The result reported here may raise hopes of graphene-based electronics with ultra-low dissipation. PMID:27312315

  1. Direct imaging of topological edge states at a bilayer graphene domain wall

    NASA Astrophysics Data System (ADS)

    Yin, Long-Jing; Jiang, Hua; Qiao, Jia-Bin; He, Lin

    2016-06-01

    The AB-BA domain wall in gapped graphene bilayers is a rare naked structure hosting topological electronic states. Although it has been extensively studied in theory, a direct imaging of its topological edge states is still missing. Here we image the topological edge states at the graphene bilayer domain wall by using scanning tunnelling microscope. The simultaneously obtained atomic-resolution images of the domain wall provide us unprecedented opportunities to measure the spatially varying edge states within it. The one-dimensional conducting channels are observed to be mainly located around the two edges of the domain wall, which is reproduced quite well by our theoretical calculations. Our experiment further demonstrates that the one-dimensional topological states are quite robust even in the presence of high magnetic fields. The result reported here may raise hopes of graphene-based electronics with ultra-low dissipation.

  2. Direct imaging of neural currents using ultra-low field magnetic resonance techniques

    DOEpatents

    Volegov, Petr L.; Matlashov, Andrei N.; Mosher, John C.; Espy, Michelle A.; Kraus, Jr., Robert H.

    2009-08-11

    Using resonant interactions to directly and tomographically image neural activity in the human brain using magnetic resonance imaging (MRI) techniques at ultra-low field (ULF), the present inventors have established an approach that is sensitive to magnetic field distributions local to the spin population in cortex at the Larmor frequency of the measurement field. Because the Larmor frequency can be readily manipulated (through varying B.sub.m), one can also envision using ULF-DNI to image the frequency distribution of the local fields in cortex. Such information, taken together with simultaneous acquisition of MEG and ULF-NMR signals, enables non-invasive exploration of the correlation between local fields induced by neural activity in cortex and more `distant` measures of brain activity such as MEG and EEG.

  3. Direct imaging of topological edge states at a bilayer graphene domain wall

    PubMed Central

    Yin, Long-Jing; Jiang, Hua; Qiao, Jia-Bin; He, Lin

    2016-01-01

    The AB–BA domain wall in gapped graphene bilayers is a rare naked structure hosting topological electronic states. Although it has been extensively studied in theory, a direct imaging of its topological edge states is still missing. Here we image the topological edge states at the graphene bilayer domain wall by using scanning tunnelling microscope. The simultaneously obtained atomic-resolution images of the domain wall provide us unprecedented opportunities to measure the spatially varying edge states within it. The one-dimensional conducting channels are observed to be mainly located around the two edges of the domain wall, which is reproduced quite well by our theoretical calculations. Our experiment further demonstrates that the one-dimensional topological states are quite robust even in the presence of high magnetic fields. The result reported here may raise hopes of graphene-based electronics with ultra-low dissipation. PMID:27312315

  4. Accuracy analysis of direct georeferenced UAV images utilising low-cost navigation sensors

    NASA Astrophysics Data System (ADS)

    Briese, Christian; Wieser, Martin; Verhoeven, Geert; Glira, Philipp; Doneus, Michael; Pfeifer, Norbert

    2014-05-01

    Unmanned aerial vehicles (UAVs), also known as unmanned airborne systems (UAS) or remotely piloted airborne systems (RPAS), are an established platform for close range airborne photogrammetry. Compared to manned platforms, the acquisition of local remote sensing data by UAVs is a convenient and very flexible option. For the application in photogrammetry UAVs are typically equipped with an autopilot and a lightweight digital camera. The autopilot includes several navigation sensors, which might allow an automated waypoint flight and offer a systematic data acquisition of the object resp. scene of interest. Assuming a sufficient overlap between the captured images, the position (3 coordinates: x, y, z) and the orientation (3 angles: roll, pitch, yaw) of the images can be estimated within a bundle block adjustment. Subsequently, coordinates of observed points that appear in at least two images, can be determined by measuring their image coordinates or a dense surface model can be generated from all acquired images by automated image matching. For the bundle block adjustment approximate values of the position and the orientation of the images are needed. To gather this information, several methods exist. We introduce in this contribution one of them: the direct georeferencing of images by using the navigation sensors (mainly GNSS and INS) of a low-cost on-board autopilot. Beside automated flights, the autopilot offers the possibility to record the position and the orientation of the platform during the flight. These values don't correspond directly to those of the images. To compute the position and the orientation of the images two requirements must be fulfilled. First the misalignment angles and the positional differences between the camera and the autopilot must be determined (mounting calibration). Second the synchronization between the camera and the autopilot has to be established. Due to the limited accuracy of the navigation sensors, a small number of ground

  5. Cryogenic-temperature electron microscopy direct imaging of carbon nanotubes and graphene solutions in superacids.

    PubMed

    Kleinerman, O; Parra-Vasquez, A Nicholas G; Green, M J; Behabtu, N; Schmidt, J; Kesselman, E; Young, C C; Cohen, Y; Pasquali, M; Talmon, Y

    2015-07-01

    Cryogenic electron microscopy (cryo-EM) is a powerful tool for imaging liquid and semiliquid systems. While cryogenic transmission electron microscopy (cryo-TEM) is a standard technique in many fields, cryogenic scanning electron microscopy (cryo-SEM) is still not that widely used and is far less developed. The vast majority of systems under investigation by cryo-EM involve either water or organic components. In this paper, we introduce the use of novel cryo-TEM and cryo-SEM specimen preparation and imaging methodologies, suitable for highly acidic and very reactive systems. Both preserve the native nanostructure in the system, while not harming the expensive equipment or the user. We present examples of direct imaging of single-walled, multiwalled carbon nanotubes and graphene, dissolved in chlorosulfonic acid and oleum. Moreover, we demonstrate the ability of these new cryo-TEM and cryo-SEM methodologies to follow phase transitions in carbon nanotube (CNT)/superacid systems, starting from dilute solutions up to the concentrated nematic liquid-crystalline CNT phases, used as the 'dope' for all-carbon-fibre spinning. Originally developed for direct imaging of CNTs and graphene dissolution and self-assembly in superacids, these methodologies can be implemented for a variety of highly acidic systems, paving a way for a new field of nonaqueous cryogenic electron microscopy. PMID:25818279

  6. Anisotropic conductivity tensor imaging in MREIT using directional diffusion rate of water molecules

    NASA Astrophysics Data System (ADS)

    In Kwon, Oh; Jeong, Woo Chul; Sajib, Saurav Z. K.; Kim, Hyung Joong; Woo, Eung Je

    2014-06-01

    Magnetic resonance electrical impedance tomography (MREIT) is an emerging method to visualize electrical conductivity and/or current density images at low frequencies (below 1 KHz). Injecting currents into an imaging object, one component of the induced magnetic flux density is acquired using an MRI scanner for isotropic conductivity image reconstructions. Diffusion tensor MRI (DT-MRI) measures the intrinsic three-dimensional diffusion property of water molecules within a tissue. It characterizes the anisotropic water transport by the effective diffusion tensor. Combining the DT-MRI and MREIT techniques, we propose a novel direct method for absolute conductivity tensor image reconstructions based on a linear relationship between the water diffusion tensor and the electrical conductivity tensor. We first recover the projected current density, which is the best approximation of the internal current density one can obtain from the measured single component of the induced magnetic flux density. This enables us to estimate a scale factor between the diffusion tensor and the conductivity tensor. Combining these values at all pixels with the acquired diffusion tensor map, we can quantitatively recover the anisotropic conductivity tensor map. From numerical simulations and experimental verifications using a biological tissue phantom, we found that the new method overcomes the limitations of each method and successfully reconstructs both the direction and magnitude of the conductivity tensor for both the anisotropic and isotropic regions.

  7. Tomographic imaging of a target directly irradiated in experiments on the Iskra-5 iodine laser facility

    SciTech Connect

    Bondarenko, S V; Garanin, R V; Garanin, Sergey G; Zhidkov, N V; Oreshkov, O V; Potapov, S V; Suslov, N A; Frolova, N V

    2010-12-29

    We set forth the data of experiments involving direct microtarget irradiation by the 12 second-harmonic beams ({lambda} = 0.66 {mu}m) of iodine laser radiation carried out on the Iskra-5 facility. For microtargets we employed glass shells {approx}500 {mu}m in diameter with {approx}1-{mu}m thick walls, which were filled with a DT mixture at a pressure p{sub DT} {approx} 3-4 atm. In one of these experiments, a tomographic image of the microtarget was recorded from the images obtained using pinhole cameras, which were arranged along seven different directions. The pinhole images were acquired in the X-ray radiation with photon energies above 1.5 keV. The procedure used for reconstructing the volume luminosity of the microtarget is described. An analysis of the tomographic image suggests that the compressed microtarget domain possesses a complex asymmetric shape; 20-30 {mu}m sized structural elements being clearly visible. The resultant data set allowed us to estimate the initial nonuniformity of microtarget surface irradiation by the laser radiation. The rms nonuniformity of microtarget irradiance was estimated at {approx}60 %. (interaction of laser radiation with targets)

  8. JJ1017 image examination order codes: standardized codes supplementary to DICOM for imaging modality, region, and direction

    NASA Astrophysics Data System (ADS)

    Kimura, Michio; Kuranishi, Makoto; Sukenobu, Yoshiharu; Watanabe, Hiroki; Nakajima, Takashi; Morimura, Shinya; Kabata, Shun

    2002-05-01

    The DICOM standard includes non-image data information such as image study ordering data and performed procedure data, which are used for sharing information between HIS/RIS/PACS/modalities, which is essential for IHE. In order to bring such parts of the DICOM standard into force in Japan, a joint committee of JIRA and JAHIS (vendor associations) established JJ1017 management guideline. It specifies, for example, which items are legally required in Japan while remaining optional in the DICOM standard. Then, what should be used for the examination type, regional, and directional codes? Our investigation revealed that DICOM tables do not include items that are sufficiently detailed for use in Japan. This is because radiology departments (radiologists) in the US exercise greater discretion in image examination than in Japan, and the contents of orders from requesting physicians do not include the extra details used in Japan. Therefore, we have generated the JJ1017 code for these 3 codes for use based on the JJ1017 guidelines. The stem part of the JJ1017 code partially employs the DICOM codes in order to remain in line with the DICOM standard. JJ1017 codes are to be included not only in IHE-J specifications, also in Ministry recommendations of health data exchange.

  9. Fetal head detection and measurement in ultrasound images by a direct inverse randomized Hough transform

    NASA Astrophysics Data System (ADS)

    Lu, Wei; Tan, Jinglu; Floyd, Randall C.

    2005-04-01

    Object detection in ultrasound fetal images is a challenging task for the relatively low resolution and low signal-to-noise ratio. A direct inverse randomized Hough transform (DIRHT) is developed for filtering and detecting incomplete curves in images with strong noise. The DIRHT combines the advantages of both the inverse and the randomized Hough transforms. In the reverse image, curves are highlighted while a large number of unrelated pixels are removed, demonstrating a "curve-pass filtering" effect. Curves are detected by iteratively applying the DIRHT to the filtered image. The DIRHT was applied to head detection and measurement of the biparietal diameter (BPD) and head circumference (HC). No user input or geometric properties of the head were required for the detection. The detection and measurement took 2 seconds for each image on a PC. The inter-run variations and the differences between the automatic measurements and sonographers" manual measurements were small compared with published inter-observer variations. The results demonstrated that the automatic measurements were consistent and accurate. This method provides a valuable tool for fetal examinations.

  10. Computer Based Direct Digital Film Recording For Hard Copy Of Medical Images

    NASA Astrophysics Data System (ADS)

    Laskin, Bruce S.

    1984-06-01

    With the introduction of digital medical imaging modalities and picture archiving and communications systems (PACS) the necessary and desirable capabilities of a film recorder for hard-copy output will vary from the specifications of the current video-based recorder. Image data can be presented to the film recorder in a digital rather than analog video format. The resulting film image is no longer subject to degradation due to nonlinearities in the video portion of the recorder. Spatial resolution is also greatly enhanced (4096 x 4096 pixels). The inherent data processing capabilities of the digital film recorder allow a number of additional functions to be performed internally. Features of the system to be discussed include automatic calibration, automatic failure diagnosis, data compression and expansion, data error detection and correction, gamma and exposure compensation, alphanumeric and graphic frame identification, graphic image recording (EKG, EEG, EMG), color capability, data format conversion, multi-format multi-modality sequences, print spooling from multiple image sources and direct connection to a PACS network.